These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Feasibility of Neural Stimulation With Floating-Light-Activated Microelectrical Stimulators  

PubMed Central

Neural microstimulation is becoming a powerful tool for the restoration of impaired functions in the central nervous system. Microelectrode arrays with fine wire interconnects have traditionally been used in the development of these neural prosthetic devices. However, these interconnects are usually the most vulnerable part of the neuroprosthetic implant that can eventually cause the device to fail. In this paper, we investigate the feasibility of floating-light-activated microelectrical stimulators (FLAMES) for wireless neural stimulation. A computer model was developed to simulate the micro stimulators for typical requirements of neural activation in the human white and gray matters. First, the photon densities due to a circular laser beam were simulated in the neural tissue at near-infrared (NIR) wavelengths. Temperature elevation in the tissue was calculated and the laser power was retrospectively adjusted to 325 and 250 mW/cm2 in the gray and white matters, respectively, to limit ?T to 0.5 °C. Total device area of the FLAMES increased with all parameters considered but decreased with the output voltage. We conclude that the number of series photodiodes in the device can be used as a free parameter to minimize the device size. The results suggest that floating, optically activated stimulators are feasible at submillimeter sizes for the activation of the brain cortex or the spinal cord. PMID:21552457

Abdo, Ammar; Sahin, Mesut

2011-01-01

2

Floating Light-Activated Micro Electrical Stimulators Tested in the Rat Spinal Cord  

PubMed Central

Microelectrodes of neural stimulation utilize fine wires for electrical connections to driving electronics. Breakage of these wires and the neural tissue response due to their tethering forces are major problems encountered with long term implantation of microelectrodes. The lifetime of an implant for neural stimulation can be substantially improved if the wire interconnects are eliminated. Thus, we proposed a floating light-activated micro electrical stimulator (FLAMES) for wireless neural stimulation. In this paradigm, a laser beam at near infrared (NIR) wavelengths will be used as a means of energy transfer to the device. In this study, microstimulators of various sizes were fabricated, with two cascaded GaAs p-i-n photodiodes, and tested in the rat spinal cord. A train of NIR pulses (0.2 ms, 50 Hz) was sent through the tissue to wirelessly activate the devices and generate the stimulus current. The forces elicited by intraspinal stimulation were measured from the ipsilateral forelimb with a force transducer. The largest forces were around 1.08N, a significant level of force for the rat forelimb motor function. These in vivo tests suggest that the FLAMES can be used for intraspinal microstimulation even for the deepest implant locations in the rat spinal cord. The power required to generate a threshold arm movement was investigated as the laser source was moved away from the microstimulator. The results indicate that the photon density does not decrease substantially for horizontal displacements of the source that are in the same order as the beam radius. This gives confidence that the stimulation threshold may not be very sensitive to small displacement of the spinal cord relative to the spine-mounted optical power source. PMID:21914931

Abdo, Ammar; Sahin, Mesut; Freedman, David S.; Cevik, Elif; Spuhler, Philipp S.; Unlu, M. Selim

2011-01-01

3

Floating Light-Activated Micro-Electrical Stimulators Mesut Sahin1  

E-print Network

these questions, first we have developed a finite element model of a floating micro-stimulator with bipolar the contacts with titanium nitride (TiN). The voltage generated by an individual diode in a volume conductor

4

33 CFR 149.550 - What are the requirements for lights on a floating hose string?  

Code of Federal Regulations, 2011 CFR

...false What are the requirements for lights on a floating hose string? 149...AND EQUIPMENT Aids to Navigation Lights on Floating Hose Strings § 149.550 What are the requirements for lights on a floating hose string?...

2011-07-01

5

33 CFR 149.550 - What are the requirements for lights on a floating hose string?  

Code of Federal Regulations, 2012 CFR

...false What are the requirements for lights on a floating hose string? 149...AND EQUIPMENT Aids to Navigation Lights on Floating Hose Strings § 149.550 What are the requirements for lights on a floating hose string?...

2012-07-01

6

33 CFR 149.550 - What are the requirements for lights on a floating hose string?  

Code of Federal Regulations, 2013 CFR

...false What are the requirements for lights on a floating hose string? 149...AND EQUIPMENT Aids to Navigation Lights on Floating Hose Strings § 149.550 What are the requirements for lights on a floating hose string?...

2013-07-01

7

33 CFR 149.550 - What are the requirements for lights on a floating hose string?  

Code of Federal Regulations, 2014 CFR

...false What are the requirements for lights on a floating hose string? 149...AND EQUIPMENT Aids to Navigation Lights on Floating Hose Strings § 149.550 What are the requirements for lights on a floating hose string?...

2014-07-01

8

Charge retention characteristics of silicide-induced crystallized polycrystalline silicon floating gate thin-film transistors for active matrix organic light-emitting diode.  

PubMed

In this work, non-volatile memory thin-film transistor (NVM-TFT) was fabricated by nickel silicide-induced laterally crystallized (SILC) polycrystalline silicon (poly-Si) as the active layer. The nickel seed silicide-induced crystallized (SIC) poly-Si was used as storage layer which is embedded in the gate insulator. The novel unit pixel of active matrix organic light-emitting diode (AMOLED) using NVM-TFT is proposed and investigated the electrical and optical performance. The threshold voltage shift showed 17.2 V and the high reliability of retention characteristic was demonstrated until 10 years. The retention time can modulate the recharge refresh time of the unit pixel of AMOLED up to 5000 sec. PMID:24245194

Park, Jae Hyo; Son, Se Wan; Byun, Chang Woo; Kim, Hyung Yoon; Joo, So Na; Lee, Yong Woo; Yun, Seung Jae; Joo, Seung Ki

2013-10-01

9

CMOS Active-Pixel Image Sensor With Simple Floating Gates  

NASA Technical Reports Server (NTRS)

Experimental complementary metal-oxide/semiconductor (CMOS) active-pixel image sensor integrated circuit features simple floating-gate structure, with metal-oxide/semiconductor field-effect transistor (MOSFET) as active circuit element in each pixel. Provides flexibility of readout modes, no kTC noise, and relatively simple structure suitable for high-density arrays. Features desirable for "smart sensor" applications.

Fossum, Eric R.; Nakamura, Junichi; Kemeny, Sabrina E.

1996-01-01

10

"JCE" Classroom Activity #108. Using Archimedes' Principle to Explain Floating and Sinking Cans  

ERIC Educational Resources Information Center

In this activity, students (working alone or in groups) measure the mass of several soda cans (diet and regular soda) along with the mass of water that each can displaces. The students are then asked to compare these two mass values for the sinking cans and for the floating cans. The purpose of this activity is for students to determine that the…

Sanger, Michael J.

2011-01-01

11

"Does it Float?" An inquiry-based activity investigating buoyancy  

NSDL National Science Digital Library

This is an inquiry-based activity in which students will need to work together as a class to solve the following problem: they must construct a "boat" entirely out of modeling clay that is capable of supporting 150 grams of cargo without sinking.

Sean Sletten

12

Lagrangian floats as sea floor imaging platforms  

NASA Astrophysics Data System (ADS)

There is a persistent need for high resolution photographic images of the sea floor and associated biota for marine habitat classification and fisheries stock assessment. This paper presents a novel low cost Lagrangian imaging platform that offers high quality images with reduced operational demands in comparison to existing methodologies such as diver surveys, drop cameras, ship towed systems and dedicated remote or autonomous underwater vehicles. The platform consists of a recently developed bottom following Lagrangian float fit with down looking stereo cameras and strobe lighting. The float can use active ballasting to perform constant altitude photographic drift surveys in coastal waters over varying bathymetry. Images from the float can be used to create large photomosaics, stereographic bathymetry estimates and image-derived current measurements. Test data are presented to demonstrate the operation of the Lagrangian float and summarize the data products.

Roman, Chris; Inglis, Gabrielle; McGilvray, Bryan

2011-10-01

13

33 CFR 149.550 - What are the requirements for lights on a floating hose string?  

Code of Federal Regulations, 2010 CFR

...must display the following lights at night and during periods of restricted...2 miles (3.7 km) on a clear, dark night; (4) Not less than 1 or more...2 miles (3.7 km) on a clear, dark night; and (3) One meter (3...

2010-07-01

14

How much floating light nonaqueous phase liquid can a phreatic surface sustain? Riesenkampf's scheme revisited  

NASA Astrophysics Data System (ADS)

Steady, Darcian, one-phase, phreatic surface flow of groundwater into a horizontal well with a pancake lens of light nonaqueous phase liquid (LNAPL) accumulated in the water table trough is studied by the method of complex analysis. A sharp interface model assumes groundwater capped by two isobaric limbs (groundwater-vadose zone interfaces) of a free surface with an in-between cambered segment of an immiscible LNAPL-water interface, along which pressure is hydrostatically increasing with the depth of the LNAPL "channel." The complex potential polygon is mapped onto an auxiliary half plane where the complex physical coordinate of the flow domain is represented in terms of singular integrals as a solution of the Keldysh-Sedov problem. The shapes of semi-infinite "wings" of the water table contacting the vadose zone gas and of a finite length LNAPL-groundwater interface are found from parametric equations that involve the sink strength and location with respect to the pancake surface, the ordinate of the lowest trough point, and the volume of LNAPL accreted in the lens. Critical conditions, corresponding to the lens contour cusping toward the sink, are found. The Riesenkampf solution contains a free parameter, which is fixed by specifying either a point on the free surface or the volume of the trough-intercepted LNAPL.

Kacimov, Anvar; Obnosov, Yurii; Al-Maktoumi, Ali; Al-Balushi, Mohammed

2011-11-01

15

What Makes a Boat Float?  

NSDL National Science Digital Library

Whether or not a boat floats is determined by its shape and density. In this activity, students discover how and why boats float by designing different hull shapes and finding which design holds the most weight. Students record, calculate, and interpret data as they learn about buoyancy in this hands-on activity.

Eichinger, John

2009-05-01

16

Floating Paper Clip  

NSDL National Science Digital Library

In this activity, challenge learners to float a paper clip in a cup of water. Learners discover that a paper clip will sink in a cup of water, except when it is placed on a piece of paper towel. Use this activity to demonstrate the principles of surface tension, adhesion/cohesion, and gravity.

Boston, Wgbh

2002-01-01

17

Root Beer Float  

NSDL National Science Digital Library

In this quick activity/demonstration about density, learners examine what happens when two cans of root beer--one diet and one regular--are placed in a large container of water. Do they sink or float? Use this activity to introduce learners to the importance of density as well as the nutritional content of soft drinks.

2012-06-26

18

With a letter-searched prime, boat primes float but swim and coat don't: further evidence for automatic semantic activation.  

PubMed

Letter search (LS) on the prime typically eliminates semantic priming (swim-float) and orthographic/ phonological (O/P) priming (coat-float) but not morphological priming (marked-mark). However, LS on the prime does not reduce semantic priming for low-frequency targets (Tse & Neely, 2007). These findings suggest that semantic activation survives LS but decays during LS to a low level that can be detected only with sensitive measures, which are afforded by low-frequency targets and morphologically related primes and targets. In the present research, we show that LS on the prime results in 0 msec of semantic priming (e.g., swim-float) and 11 msec of O/P priming (e.g., coat-float), both of which are statistically null, whereas the LS semantic+O/P priming effect for primes and targets that do not share a morpheme (e.g., boat-float) is a robust 37 msec. Discussion focuses on the automaticity of semantic activation and whether morphological priming is mediated by (1) a morphemic representation that is separate from semantic representations or (2) activation combined from semantics and orthography/phonology. PMID:18792514

Pastizzo, Matthew J; Neely, James H; Tse, Chi-Shing

2008-08-01

19

Floating In Air  

NSDL National Science Digital Library

Float a ping-pong ball with a hairdryer, as a demonstration of Bernoulli's principle. This classic physics activity includes a twist with the addition of a toilet paper tube that allows learners to explore air pressure in a different way.

2014-05-28

20

On floats and float tests  

NASA Technical Reports Server (NTRS)

The principal source of information on float resistance is the model test. In view of the insuperable difficulties opposing any attempt at theoretical treatment of the resistance problem, particularly at attitudes which tend toward satisfactory take-off, such as the transitory stage to planing, the towing test is and will remain the primary method for some time.

Seewald, Friedrich

1931-01-01

21

Microwave and Light-Wave Measurements for Nematic-Liquid-Crystal-Loaded Phase Shifter Using Coplanar Waveguide with Floating Electrode  

NASA Astrophysics Data System (ADS)

We fabricated an experimental liquid-crystal-loaded coplanar waveguide with a floating electrode (CPW-FE) phase shifter with a straight-line structure and investigated its response time and phase characteristics by performing microwave measurements while varying structural parameters. We also constructed a liquid crystal optical cell using indium-tin-oxide (ITO) glass to simulate the CPW-FE structure and obtained measurements by capturing moving pictures using a polarized microscope. By comparing successive frames of this video and measuring response times to a steady state, we examined the behavior of liquid crystal molecules upon the application of a voltage to the liquid crystal layer. These observations enabled a qualitative physical interpretation of the results obtained by the above microwave measurements.

Kamei, Toshihisa; Moritake, Hiroshi; Utsumi, Yozo

2010-01-01

22

Floating layer recovery apparatus  

SciTech Connect

This patent describes an apparatus for recovery of a layer of a first underground liquid floating on a second underground liquid in a well. It comprises: first float means disposed in the well in the first liquid, the float means having an effective buoyancy such that it floats in the first liquid; second float means disposed in the well in the first liquid, the float means having an effective buoyancy such that it floats near the bottom of the first liquid, the second float means having top, side and bottom surfaces; an inlet means disposed on the second float surface for permitting entry of the first liquid; conduit means coupled to the inlet means and extending below the second float means; third float means disposed in the second liquid and having an effective buoyancy such that the third float means will remain submerged in the second liquid, the conduit means being coupled to the third float; the guide means for slidably connecting the second float between the first and third float means.

Newcomer, K.; Richter, S.

1991-03-12

23

Mitochondrial electron transport protects floating leaves of long leaf pondweed (Potamogeton nodosus Poir) against photoinhibition: comparison with submerged leaves.  

PubMed

Investigations were carried to unravel mechanism(s) for higher tolerance of floating over submerged leaves of long leaf pondweed (Potamogeton nodosus Poir) against photoinhibition. Chloroplasts from floating leaves showed ~5- and ~6.4-fold higher Photosystem (PS) I (reduced dichlorophenol-indophenol ? methyl viologen ? O2) and PS II (H2O ? parabenzoquine) activities over those from submerged leaves. The saturating rate (V max) of PS II activity of chloroplasts from floating and submerged leaves reached at ~600 and ~230 µmol photons m(-2) s(-1), respectively. Photosynthetic electron transport rate in floating leaves was over 5-fold higher than in submerged leaves. Further, floating leaves, as compared to submerged leaves, showed higher F v/F m (variable to maximum chlorophyll fluorescence, a reflection of PS II efficiency), as well as a higher potential to withstand photoinhibitory damage by high light (1,200 µmol photons m(-2) s(-1)). Cells of floating leaves had not only higher mitochondria to chloroplast ratio, but also showed many mitochondria in close vicinity of chloroplasts. Electron transport (NADH ? O2; succinate ? O2) in isolated mitochondria of floating leaves was sensitive to both cyanide (CN(-)) and salicylhydroxamic acid (SHAM), whereas those in submerged leaves were sensitive to CN(-), but virtually insensitive to SHAM, revealing the presence of alternative oxidase in mitochondria of floating, but not of submerged, leaves. Further, the potential of floating leaves to withstand photoinhibitory damage was significantly reduced in the presence of CN(-) and SHAM, individually and in combination. Our experimental results establish that floating leaves possess better photosynthetic efficiency and capacity to withstand photoinhibition compared to submerged leaves; and mitochondria play a pivotal role in protecting photosynthetic machinery of floating leaves against photoinhibition, most likely by oxidation of NAD(P)H and reduction of O2. PMID:25366828

Shabnam, Nisha; Sharmila, P; Sharma, Anuradha; Strasser, Reto J; Govindjee; Pardha-Saradhi, P

2014-11-01

24

The Northern Lights: Aurora Activity and Latitude  

NSDL National Science Digital Library

This activity allows students to make and use a geographic plot of aurora location and activity to create their own forecasting relationship for a selected longitude in North America. They will discover that there is a relationship between the appearance of the aurora and the amount of disturbance to Earth's magnetic field and as the magnetic field becomes more disturbed, the Northern Lights will be visible further south from the Arctic region. By measuring these disturbances, they can predict what the latitude of the southern edge of the Northern Lights will be.

Odenwald, Sten

25

Green laser light activates the inner ear  

NASA Astrophysics Data System (ADS)

The hearing performance with conventional hearing aids and cochlear implants is dramatically reduced in noisy environments and for sounds more complex than speech (e. g. music), partially due to the lack of localized sensorineural activation across different frequency regions with these devices. Laser light can be focused in a controlled manner and may provide more localized activation of the inner ear, the cochlea. We sought to assess whether visible light with parameters that could induce an optoacoustic effect (532 nm, 10-ns pulses) would activate the cochlea. Auditory brainstem responses (ABRs) were recorded preoperatively in anesthetized guinea pigs to confirm normal hearing. After opening the bulla, a 50-?m core-diameter optical fiber was positioned in the round window niche and directed toward the basilar membrane. Optically induced ABRs (OABRs), similar in shape to those of acoustic stimulation, were elicited with single pulses. The OABR peaks increased with energy level (0.6 to 23 ?J/pulse) and remained consistent even after 30 minutes of continuous stimulation at 13 ?J, indicating minimal or no stimulation-induced damage within the cochlea. Our findings demonstrate that visible light can effectively and reliably activate the cochlea without any apparent damage. Further studies are in progress to investigate the frequency-specific nature and mechanism of green light cochlear activation.

Wenzel, Gentiana I.; Balster, Sven; Zhang, Kaiyin; Lim, Hubert H.; Reich, Uta; Massow, Ole; Lubatschowski, Holger; Ertmer, Wolfgang; Lenarz, Thomas; Reuter, Guenter

2009-07-01

26

Flinking: Neither Floating nor Sinking.  

ERIC Educational Resources Information Center

Describes an activity that challenges students to make an object that, when released under water, does not float up or sink down. The main concept this activity investigates is the density of ordinary objects in comparison to the density of water. (PR)

Wilson, Roger B.

1993-01-01

27

MAXI light curves of Active Galactic Nuclei  

NASA Astrophysics Data System (ADS)

Monitor of all-sky X-ray Image (MAXI) was designed to be capable of monitoring variability of a medium-sized sample of active galactic nuclei. We examine current reliability of the MAXI light curves. As of October 2010, the light curves of more than forty sky regions of AGN are available at the MAXI web page, http://maxi.riken.jp/. Except for obvious flux changes of bright AGN (for example, those of Mrk 421, the MAXI result of which is presented by Isobe et al. ), individual features of variability in the MAXI light curves of AGN (such as Seyfert galaxies) need careful evaluations. We review effects of data screening and flux evaluation methods on the MAXI light curves.

Ueno, S.; Maxi Team

2010-12-01

28

Exploring Floating Concrete and Beam Design.  

ERIC Educational Resources Information Center

Presents two construction activities that address both state and federal science standards and encourage students to consider career options in mathematics and science. Includes floating concrete and paper bridge activities. (YDS)

Snell, Billie G.; Snell, Luke M.

2002-01-01

29

Asymmetric catalysis activated by visible light.  

PubMed

Visible light driven organic chemistry has sparked much excitement over the last several years. This review summarizes recent progress in combining visible light activation with asymmetric catalysis, processes that are either mediated by photoinduced electron or energy transfer. The tasks of photoactivation and asymmetric catalysis are typically accomplished by dual catalyst systems but several recent reports demonstrate that they can also be effectively executed by single catalysts. Beyond the discovery of novel asymmetric transformations under mild reaction conditions, this contemporary area of organic chemistry holds promise for the development of economical and environmentally friendly methods for the asymmetric synthesis of chiral compounds. PMID:25572775

Meggers, Eric

2015-02-10

30

Potato Float  

NSDL National Science Digital Library

This is a hands-on lab activity about seawater density, specifically the relationship between density of fluid, weight of an object, and buoyancy. Learners will develop hypotheses and observe a demonstration of density to understand its role in buoyancy. They will also examine the effect of salinity on density. Background information, common preconceptions, a glossary and more is included. This activity is part of the Aquarius Hands-on Laboratory Activities.

31

Potato Float  

NSDL National Science Digital Library

How can a potato wedge be made to hover in the center of a glass of liquid? This material is part of a series of hands-on science activities designed to arouse student interest. Here students investigate density using potato wedges and water and sugar water solutions. The activity includes a description, a list of science process skills and complex reasoning strategies being used, and a compilation of applicable national science standards for grades K-12. Also provided are content topics, a list of necessary supplies, instructions to perform the activity, and presentation techniques. The activity's content is explained, and assessment suggestions are provided.

Mid-continent Research for Education and Learning (McREL); Jacobs, Steve

2004-01-01

32

Light-activated self-propelled colloids.  

PubMed

Light-activated self-propelled colloids are synthesized and their active motion is studied using optical microscopy. We propose a versatile route using different photoactive materials, and demonstrate a multiwavelength activation and propulsion. Thanks to the photoelectrochemical properties of two semiconductor materials (?-Fe2O3 and TiO2), a light with an energy higher than the bandgap triggers the reaction of decomposition of hydrogen peroxide and produces a chemical cloud around the particle. It induces a phoretic attraction with neighbouring colloids as well as an osmotic self-propulsion of the particle on the substrate. We use these mechanisms to form colloidal cargos as well as self-propelled particles where the light-activated component is embedded into a dielectric sphere. The particles are self-propelled along a direction otherwise randomized by thermal fluctuations, and exhibit a persistent random walk. For sufficient surface density, the particles spontaneously form 'living crystals' which are mobile, break apart and reform. Steering the particle with an external magnetic field, we show that the formation of the dense phase results from the collisions heads-on of the particles. This effect is intrinsically non-equilibrium and a novel principle of organization for systems without detailed balance. Engineering families of particles self-propelled by different wavelength demonstrate a good understanding of both the physics and the chemistry behind the system and points to a general route for designing new families of self-propelled particles. PMID:25332383

Palacci, J; Sacanna, S; Kim, S-H; Yi, G-R; Pine, D J; Chaikin, P M

2014-11-28

33

Floating Candles  

NSDL National Science Digital Library

In this chemistry activity, learners observe a combustion reaction and deduce the components necessary for the reaction to occur. They will also see the relationship between pressure, volume, and number of molecules for gasses. This activity, which can also be conducted as a demonstration, illustrates Charles's Law and Boyle's Law.

House, The S.

2014-01-28

34

Anomalous Light Phenomena vs. Bioelectric Brain Activity  

NASA Astrophysics Data System (ADS)

We present a research proposal concerning the instrumented investigation of anomalous light phenomena that are apparently correlated with particular mind states, such as prayer, meditation or psi. Previous research by these authors demonstrate that such light phenomena can be monitored and measured quite efficiently in areas of the world where they are reported in a recurrent way. Instruments such as optical equipment for photography and spectroscopy, VLF spectrometers, magnetometers, radar and IR viewers were deployed and used massively in several areas of the world. Results allowed us to develop physical models concerning the structural and time-variable behaviour of light phenomena, and their kinematics. Recent insights and witnesses have suggested to us that a sort of "synchronous connection" seems to exist between plasma-like phenomena and particular mind states of experiencers who seem to trigger a light manifestation which is very similar to the one previously investigated. The main goal of these authors is now aimed at the search for a concrete "entanglement-like effect" between the experiencer's mind and the light phenomena, in such a way that both aspects are intended to be monitored and measured simultaneously using appropriate instrumentation. The goal of this research project is twofold: a) to verify quantitatively the existence of one very particular kind of mind-matter interaction and to study in real time its physical and biophysical manifestations; b) to repeat the same kind of experiment using the same test-subject in different locations and under various conditions of geomagnetic activity.

Teodorani, M.; Nobili, G.

35

Light and dark-activated biocidal activity of conjugated polyelectrolytes.  

PubMed

This Spotlight on Applications provides an overview of a research program that has focused on the development and mechanistic study of cationic conjugated polyelectrolytes (CPEs) that function as light- and dark-active biocidal agents. Investigation has centered on poly-(phenylene ethynylene) (PPE) type conjugated polymers that are functionalized with cationic quaternary ammonium solubilizing groups. These polymers are found to interact strongly with Gram-positive and Gram-negative bacteria, and upon illumination with near-UV and visible light act to rapidly kill the bacteria. Mechanistic studies suggest that the cationic PPE-type polymers efficiently sensitize singlet oxygen ((1)O(2)), and this cytotoxic agent is responsible for initiating the sequence of events that lead to light-activated bacterial killing. Specific CPEs also exhibit dark-active antimicrobial activity, and this is believed to arise due to interactions between the cationic/lipophilic polymers and the negatively charged outer membrane characteristic of Gram-negative bacteria. Specific results are shown where a cationic CPE with a degree of polymerization of 49 exhibits pronounced light-activated killing of E. coli when present in the cell suspension at a concentration of 1 ?g mL(-1). PMID:21755955

Ji, Eunkyung; Corbitt, Thomas S; Parthasarathy, Anand; Schanze, Kirk S; Whitten, David G

2011-08-01

36

Floating portable pump  

SciTech Connect

A floating portable pump is constructed of a float defining a well for containing water, a centrifugal pump supported on the float with its impeller shaft extending vertically and with its suction inlet submerged in water in the well, and an internal combustion engine arranged to drive the pump impeller. The pump and engine are secured together on the float in an arrangement such that the engine causes rotation of the pump impeller to cause the pump to draw water from the well through its suction inlet and discharge water from the pump discharge.

Eberhardt, H. A.

1985-11-19

37

Statistical analysis of the metrological properties of float glass  

NASA Astrophysics Data System (ADS)

The radius of curvature, slope error, surface roughness and associated height distribution and power spectral density of uncoated commercial float glass samples have been measured in our Canadian Light Source Optical Metrology Facility, using our Micromap-570 surface profiler and long trace profilometer. The statistical differences in these parameters have been investigated between the tin and air sides of float glass. The effect of soaking the float glass in sulfuric acid to try to dissolve the tin contamination has also been investigated, and untreated and post-treatment surface roughness measurements compared. We report the results of our studies on these float glass samples.

Yates, Brian W.; Duffy, Alan M.

2008-08-01

38

Can flexibility help you float?  

NASA Astrophysics Data System (ADS)

We consider the role of flexibility in the weight-bearing characteristics of bodies floating at an interface. Specifically, we develop a theoretical model for a two-dimensional thin floating plate that yields the maximum stable plate load and optimal stiffness for weight support. Plates small relative to the capillary length are primarily supported by surface tension, and their weight-bearing potential does not benefit from flexibility. Above a critical size comparable to the capillary length, flexibility assists interfacial flotation. For plates on the order of and larger than the capillary length, deflection from an initially flat shape increases the force resulting from hydrostatic pressure, allowing the plate to support a greater load. In this large plate limit, the shape that bears the most weight is a semicircle, which displaces the most fluid above the plate for a fixed plate length. Exact results for maximum weight-bearing plate shapes are compared to analytic approximations made in the limits of large and small plate sizes. The value of flexibility for floating to a number of biological organisms is discussed in light of our study.

Burton, L. J.; Bush, J. W. M.

2012-10-01

39

National Synchrotron Light Source 2010 Activity Report  

SciTech Connect

This is a very exciting period for photon sciences at Brookhaven National Laboratory. It is also a time of unprecedented growth for the Photon Sciences Directorate, which operates the National Synchrotron Light Source (NSLS) and is constructing NSLS-II, both funded by the Department of Energy's Office of Science. Reflecting the quick pace of our activities, we chose the theme 'Discovery at Light Speed' for the directorate's 2010 annual report, a fiscal year bookended by October 2009 and September 2010. The year began with the news that NSLS users Venki Ramakrishnan of Cambridge University (also a former employee in Brookhaven's biology department) and Thomas A. Steitz of Yale University were sharing the 2009 Nobel Prize in Chemistry with Ada E. Yonath of the Weizmann Institute of Science. Every research project has the potential for accolades. In 2010, NSLS users and staff published close to 900 papers, with about 170 appearing in premiere journals. Those are impressive stats for a facility nearly three decades old, testament to the highly dedicated team keeping NSLS at peak performance and the high quality of its user community. Our NSLS users come from a worldwide community of scientists using photons, or light, to carry out research in energy and environmental sciences, physics, materials science, chemistry, biology and medicine. All are looking forward to the new capabilities enabled by NSLS-II, which will offer unprecedented resolution at the nanoscale. The new facility will produce x-rays more than 10,000 times brighter than the current NSLS and host a suite of sophisticated instruments for cutting-edge science. Some of the scientific discoveries we anticipate at NSLS-II will lead to major advances in alternative energy technologies, such as hydrogen and solar. These discoveries could pave the way to: (1) catalysts that split water with sunlight for hydrogen production; (2) materials that can reversibly store large quantities of electricity or hydrogen; (3) high-temperature superconducting materials that carry electricity with no loss for efficient power transmission lines; and (4) materials for solid-state lighting with half of the present power consumption. Excitement about NSLS-II is evident in many ways, most notably the extraordinary response we had to the 2010 call for beamline development proposals for the anticipated 60 or more beamlines that NSLS-II will ultimately host. A total of 54 proposals were submitted and, after extensive review, 34 were approved. Funding from both the Department of Energy and the National Institutes of Health has already been secured to support the design and construction of a number of these beamlines. FY11 is a challenging and exciting year for the NSLS-II Project as we reach the peak of our construction activity. We remain on track to complete the project by March 2014, a full 15 months ahead of schedule and with even more capabilities than originally planned. The Photon Sciences Directorate is well on its way to fulfilling our vision of being a provider of choice for world-class photon sciences and facilities.

Rowe, M.; Snyder, K. J.

2010-12-29

40

Application of floating silicon-based linear multielectrode arrays for acute recording of single neuron activity in awake behaving monkeys.  

PubMed

One of the fundamental challenges in behavioral neurophysiology in awake animals is the steady recording of action potentials of many single neurons for as long as possible. Here, we present single neuron data obtained during acute recordings mainly from premotor cortices of three macaque monkeys using a silicon-based linear multielectrode array. The most important aspect of these probes, compared with similar models commercially available, is that, once inserted into the brain using a dedicated insertion device providing an intermediate probe fixation by means of vacuum, they can be released and left floating in the brain. On the basis of our data, these features appear to provide (i) optimal physiological conditions for extracellular recordings, (ii) good or even excellent signal-to-noise ratio depending on the recorded brain area and cortical layer, and (iii) extreme stability of the signal over relatively long periods. The quality of the recorded signal did not change significantly after several penetrations into the same restricted cortical sector, suggesting limited tissue damage due to probe insertion. These results indicate that these probes offer several advantages for acute neurophysiological experiments in awake monkeys, and suggest the possibility to employ them for semichronic or even chronic studies. PMID:24434299

Bonini, Luca; Maranesi, Monica; Livi, Alessandro; Bruni, Stefania; Fogassi, Leonardo; Holzhammer, Tobias; Paul, Oliver; Ruther, Patrick

2014-08-01

41

Micromechanisms with floating pivot  

DOEpatents

A new class of tilting micromechanical mechanisms have been developed. These new mechanisms use floating pivot structures to relieve some of the problems encountered in the use of solid flexible pivots.

Garcia, Ernest J. (Albuquerque, NM)

2001-03-06

42

Floating Squares (GCMP)  

NSDL National Science Digital Library

Floating Squares: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will coat a piece of notecard with graphite (from pencil lead). We then will float the piece in two beakers containing water and a second solvent. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.

43

Active switching in metamaterials using polarization control of light  

E-print Network

We demonstrate on-demand control of localized surface plasmons in metamaterials by means of incident light polarization. An asymmetric mode, selectively excited by s-polarized light, interfere destructively with a bright element, thereby allowing the incident light to propagate at a fairly low loss, corresponding to electromagnetically induced transparency (EIT) in an atomic system. In contrast, a symmetric mode, excited by p-polarized light, directly couples with the incident light, which is analogous to the switch-off of EIT. The light polarization-dependent excitation of asymmetric and symmetric plasmon modes holds potential for active switching applications of plasmon hybridization.

Hua Xu; Byoung Seung Ham

2010-10-11

44

Floating wind turbine system  

NASA Technical Reports Server (NTRS)

A floating wind turbine system with a tower structure that includes at least one stability arm extending therefrom and that is anchored to the sea floor with a rotatable position retention device that facilitates deep water installations. Variable buoyancy for the wind turbine system is provided by buoyancy chambers that are integral to the tower itself as well as the stability arm. Pumps are included for adjusting the buoyancy as an aid in system transport, installation, repair and removal. The wind turbine rotor is located downwind of the tower structure to allow the wind turbine to follow the wind direction without an active yaw drive system. The support tower and stability arm structure is designed to balance tension in the tether with buoyancy, gravity and wind forces in such a way that the top of the support tower leans downwind, providing a large clearance between the support tower and the rotor blade tips. This large clearance facilitates the use of articulated rotor hubs to reduced damaging structural dynamic loads. Major components of the turbine can be assembled at the shore and transported to an offshore installation site.

Viterna, Larry A. (Inventor)

2009-01-01

45

Light and dark active phosphodiesterase regulation in salamander rods  

PubMed Central

We studied the activation of 3',5'-cyclic guanosine monophosphate (cGMP) phosphodiesterase (PDE) by using a cell-permeant enzyme inhibitor. Rods of Ambystoma tigrinum held in a suction electrode were jumped into a stream of 3-isobutyl-1-methylxanthine (IBMX), 0.01-1 mM. Initial transient light-sensitive currents fit the notion that dark and light-activated forms of PDE contributed independently to metabolic activity and were equivalently inhibited by IBMX (apparent Ki 30 microns). Inhibition developed within 50 ms, producing a step decrease of enzyme velocity, which could be offset by activation with flashes or steps of light. The dark PDE activity was equivalent to light activation of enzyme by 1,000 isomerization rod-1s-1, sufficient to hydrolyze the free cGMP pool (1/e) in 0.6 s. Steady light activated PDE in linear proportion to isomerization rate, the range from darkness to current saturation amounting to a 10-fold increase. The conditions for simultaneous onset of inhibitor and illumination to produce no net change of membrane current defined the apparent lifetime of light- activated PDE, TPDE* = 0.9 s, which was independent of both background illumination and current over the range 0-3 x 10(5) isomerization s-1, from 50 to 0 pA. Adaptation was a function of current rather than isomerization: jumps with different proportions of IBMX concentration to steady light intensity produced equal currents, and followed the same course of adaptation in maintained light, despite a 10-fold difference of illumination. Judged from the delay between IBMX- and light-induced currents, the dominant feedback regulatory site comes after PDE on the signal path. The dark active PDE affects the hydrolytic flux and cytoplasmic diffusion of cGMP, as well as the proportional range of the cGMP activity signal in response to light. PMID:1722240

1991-01-01

46

Blue light-activated hypocrellin B damages ovarian cancer cells  

NASA Astrophysics Data System (ADS)

In the present study, a novel blue light source from LED was used to activate hypocrellin B in ovarian cancer HO-8910 cells. Hyppcrellin B concentration was kept at 2.5 ?M and light doses from 0.5-4.0 J/cm2. Photocytotoxicity was investigated using MTT reduction assay and light microscopy after light irradiation. Cellular morphology was observed using transmission electron microscopy (TEM). MTT assay showed that the cytotoxicity of blue light-activated hypocrellin B in HO-8910 cells increased along with light dose. The observations from light microscopy reinforced the above results. TEM showed that microvillin disappearance, vacuole formation, chromatin condensation, and topical apoptotic body were observed in the cells treated by both light and hypocrellin B. The findings demonstrated that blue light from LED source could effectively activate hypocrellin B to cause the destruction of HO-8910 cells, indicating that Blue light-activated hypocrellin B might be potential therapeutic strategy in the management of ovarian cancer.

Jiang, Y.; Leung, A. W. N.; Xiang, J. Y.; Xu, C. S.

2011-10-01

47

Floating--A Key to Survival.  

ERIC Educational Resources Information Center

Described are several activities to be used to help students grasp the concept of floating. The activities include the use of a spring scale to measure the weight of the objects in air, in water, and in salt water, and a discussion of why there are differences in these weights. (DS)

Anderson, Norman

1980-01-01

48

Measurement of action spectra of light-activated processes  

NASA Astrophysics Data System (ADS)

We report on a new experimental technique suitable for measurement of light-activated processes, such as fluorophore transport. The usefulness of this technique is derived from its capacity to decouple the imaging and activation processes, allowing fluorescent imaging of fluorophore transport at a convenient activation wavelength. We demonstrate the efficiency of this new technique in determination of the action spectrum of the light mediated transport of rhodamine 123 into the parasitic protozoan Giardia duodenalis.

Ross, Justin; Zvyagin, Andrei V.; Heckenberg, Norman R.; Upcroft, Jacqui; Upcroft, Peter; Rubinsztein-Dunlop, Halina H.

2006-01-01

49

What Floats Your Boat?  

NSDL National Science Digital Library

Students use modeling clay, a material that is denser than water and thus ordinarily sinks in water, to discover the principle of buoyancy. They begin by designing and building boats out of clay that will float in water, and then refine their designs so that their boats will carry as great a load (metal washers) as possible. Building a clay boat to hold as much weight as possible is an engineering design problem. Next, they compare amount of water displaced by a lump of clay that sinks to the amount of water displaced by the same lump of clay when it is shaped so as to float. Determining the masses of the displaced water allows them to arrive at Archimedes' principle, whereby the mass of the displaced water equals the mass of the floating clay boat.

Engineering K-Phd Program

50

Activation of protein splicing with light in  

E-print Network

regulation of protein function is a key feature of living systems; experimental tools that provide-translational process, protein splicing, with light. Studies in Saccharomyces cerevisiae demonstrate that fusion-translational level7. CPS harnesses inteins, which are naturally occurring protein domains that autocatalytically

Cai, Long

51

Photo-mechanical patterning with light activated polymers.  

SciTech Connect

Light activated polymers, which are capable of mechanically responding to light, promise to offer exciting, innovative, and unique material capabilities. Such materials include: photo-radical mediated cleavage and reformation of the polymer backbone in cross-linked elastomers that results in local stress relaxation; photo-switching cross-links in shape memory polymers; and photo-isomerization of azobenzene groups contained in liquid crystal elastomers. In this paper, using our recent material model that couples multiphysical processes involved in light-activated polymers, we demonstrate that a variety of patterns can be created on light activated polymer thin films when coupling mechanical deformation with light irradiation. Here, the polymer thin film is first stretched uniaxially or biaxially. Light is then irradiated on the surface of the thin film. After light irradiation, removal external load partially recovers the initial stretching of the polymer thin film and induces patterns. The variation of the geometry of the patterns can be controlled by a variety of parameters such as initial stretching, light intensity, etc. Photo-patterning with light activated polymer therefore offers a novel way to create surface patterns.

Long, Kevin N.; Qi, H. Jerry (University of Colorado, Boulder, CO); Dunn, Martin L. (University of Colorado, Boulder, CO)

2010-11-01

52

Can flexibility help you float?  

E-print Network

We consider the role of flexibility in the weight-bearing characteristics of bodies floating at an interface. Specifically, we develop a theoretical model for a two-dimensional thin floating plate that yields the maximum ...

Burton, Lisa Janelle

53

Sink or Float? Inquiry Investigation  

NSDL National Science Digital Library

Students explore and experiment with various objects to find which materials will float or sink. They record predictions and results, and generate ideas about the properties of materials that float or sink.

54

Lightly stuffed pyrochlore structure of single-crystalline Yb2Ti2O7 grown by the optical floating zone technique  

NASA Astrophysics Data System (ADS)

Recent neutron scattering and specific heat studies on the pyrochlore Yb2Ti2O7 have revealed variations in its magnetic behavior below 265 mK. In the best samples, a sharp anomaly in the specific heat is observed at T=265 mK. Other samples, especially single crystals, have broad features in the specific heat which vary in sharpness and temperature depending on the sample, indicating that the magnetic ground state may be qualitatively different in such samples. We performed detailed comparisons of the chemical structure of a pulverized single crystal of Yb2Ti2O7, grown by the floating zone technique, to a sintered powder sample of Yb2Ti2O7. Rietveld refinements of neutron powder diffraction data on these samples reveal that the crushed single crystal is best described as a “stuffed” pyrochlore, Yb2(Ti2-xYbx)O7-x/2 with x = 0.046(4), despite perfectly stoichiometric starting material. Substituting magnetic Yb3+ on the nonmagnetic Ti4+ sublattice would introduce random exchange bonds and local lattice deformations. These are expected to be the mechanism leading to the variation of the delicate magnetic ground state of Yb2Ti2O7. Determination of the cubic cell length a could be useful as a method for characterizing the stoichiometry of nonpulverized single crystals at room temperature.

Ross, K. A.; Proffen, Th.; Dabkowska, H. A.; Quilliam, J. A.; Yaraskavitch, L. R.; Kycia, J. B.; Gaulin, B. D.

2012-11-01

55

A robust floating nanoammeter  

E-print Network

A circuit capable of measuring nanoampere currents while floating at voltages up to at least 25kV is described. The circuit relays its output to ground potential via an optical fiber. We particularly emphasize the design and construction techniques which allow robust operation in the presence of high voltage spikes and discharges.

Sauer, B E; Hudson, J J; Tarbutt, M R; Hinds, E A

2008-01-01

56

Corona from floating electrodes  

Microsoft Academic Search

It is not unusual to have insulated conducting objects located close to the conductors of a Lightning Protection System. However, the separation of these objects from the Lightning Protection System could vary from a few millimetres to some centimetres. When the system is exposed to thunderstorm electric fields, discharge could be initiated between the Lightning Protection System and the floating

Francisco Roman; Vernon Cooray; Viktor Scuka

1996-01-01

57

Compound floating pivot micromechanisms  

DOEpatents

A new class of tilting micromechanical mechanisms have been developed. These new mechanisms use compound floating pivot structures to attain far greater tilt angles than are practical using other micromechanical techniques. The new mechanisms are also capable of bi-directional tilt about multiple axes.

Garcia, Ernest J. (Albuquerque, NM)

2001-04-24

58

Light-activation of teleost rod photoreceptor elongation.  

PubMed

Rod photoreceptors in the retinas of teleost fish undergo changes in cell length in response to changing ambient light intensities. In the dark rods shorten and in the light rods elongate. These movements are mediated by actin-dependent processes which occur in the ellipsoid and myoid of the inner segment. As an approach to examining the underlying intracellular signaling pathways that link light absorption to actin-dependent motility in the inner segment, we have investigated the quantitative aspects of the light stimulus required to activate elongation in isolated rod inner/outer segments (RIS-ROS) of the green sunfish (Lepomis cyanellus). The intensity thresholds and strength-duration characteristics of the light stimulus required to activate teleost rod elongation were found to differ from those reported to activate vertebrate rod membrane hyperpolarization. In response to brief pulses of light, RIS-ROS elongated in a graded manner, both as a function of increasing light pulse intensity and light pulse duration. Half maximal activation of light-induced RIS-ROS elongation was produced by a stimulus of roughly 6 x 10(15) photons cm-2, which is calculated to bleach approximately 20% of the photopigment molecules in green sunfish rod outer segments. This degree of photopigment bleach is approximately 6-7 orders of magnitude greater than that required to elicit half maximal changes in membrane potential in other vertebrate rod preparations. Furthermore, the reciprocal relationship between light pulse intensity and duration in eliciting an equal elongation response held for relatively long light pulse durations.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8405167

Liepe, B A; Burnside, B

1993-07-01

59

Advanced Light Source: Activity report 1993  

SciTech Connect

The Advanced Light Source (ALS) produces the world`s brightest light in the ultraviolet and soft x-ray regions of the spectrum. The first low-energy third-generation synchrotron source in the world, the ALS provides unprecedented opportunities for research in science and technology not possible anywhere else. This year marked the beginning of operations and the start of the user research program at the ALS, which has already produced numerous high quality results. A national user facility located at Lawrence Berkeley Laboratory of the University of California, the ALS is available to researchers from academia, industry, and government laboratories. This report contains the following: (1) director`s message; (2) operations overview; (3) user program; (4) users` executive committee; (5) industrial outreach; (6) accelerator operations; (7) beamline control system; (8) insertion devices; (9) experimental systems; (10) beamline engineering; (11) first results from user beamlines; (12) beamlines for 1994--1995; (13) special events; (14) publications; (15) advisory panels; and (16) ALS staff.

Not Available

1994-11-01

60

Strained ruthenium complexes are potent light-activated anticancer agents.  

PubMed

Strained ruthenium (Ru) complexes have been synthesized and characterized as novel agents for photodynamic therapy (PDT). The complexes are inert until triggered by visible light, which induces ligand loss and covalent modification of DNA. An increase in cytotoxicity of 2 orders of magnitude is observed with light activation in cancer cells, and the compounds display potencies superior to cisplatin against 3D tumor spheroids. The use of intramolecular strain may be applied as a general paradigm to develop light-activated ruthenium complexes for PDT applications. PMID:22553960

Howerton, Brock S; Heidary, David K; Glazer, Edith C

2012-05-23

61

Light-Activated Pharmaceuticals: Mechanisms and Detection  

PubMed Central

Photodynamic therapy relies on the interaction between light, oxygen and a photosensitizing agent. Its medical significance relates to the ability of certain agents, usually based on porphyrin or phthalocyanine structures, to localize somewhat selectively in neoplastic cells and their vasculature. Subsequent irradiation, preferably at a sufficiently high wavelength to have a significant pathway through tissues, results in a photophysical reaction whereby the excited state of the photosensitizing agent transfers energy to molecular oxygen and results in the formation of reactive oxygen species. Analogous reactive nitrogen species are also formed. These contain both nitrogen and oxygen atoms. The net result is both direct tumor cell death and a shutdown of the tumor vasculature. Other processes may also occur that promote the anti-tumor response but these are outside the scope of this review. PMID:23990688

Kessel, David; Reiners, John

2013-01-01

62

Light onset stimulates tyrosine hydroxylase activity in isolated teleost retinas.  

PubMed

The action of tyrosine hydroxylase is the rate-limiting step in the synthesis of dopamine, the most abundant catecholamine in vertebrate retinas. I have examined the activation and regulation of this enzyme in isolated retinas of green sunfish, Lepomis cyanellus. Exposing previously dark-adapted retinas to constant illumination for a period of 10 min increased enzymatic activity 2.2-fold over that present in retinas incubated in darkness. Thus, light onset activates tyrosine hydroxylase in teleost retinas. Stimulation of the activity of tyrosine hydroxylase under these conditions was associated with a decrease in the apparent Km of the enzyme for its pteridine cofactor without a change in the apparent Vmax of the reaction. This result suggests that short-term exposure to light increases dopamine synthesis by enhancing the affinity of the enzyme for its naturally occurring cofactor. These findings are consistent with the idea that light activates dopaminergic neurons in teleost retinas. PMID:1688216

Dearry, A

1991-01-01

63

Immunoglobulin Light Chains Activate Tubular Epithelial Cells through Redox Signaling  

PubMed Central

The renal proximal tubule metabolizes circulating low-molecular-weight proteins such as Ig free light chains. In the setting of plasma cell dyscrasias, the burden of filtered protein can be very high. Endocytosis of certain nephrotoxic light chains induces H2O2 production and monocyte chemoattractant protein-1 (MCP-1) release, leading to recruitment of inflammatory cells and interstitial fibrosis, but how these processes are linked mechanistically is not well understood. This study investigated the relationship between H2O2 generated after light chain endocytosis by human proximal tubular (HK-2) cells and activation of c-Src, a redox-sensitive tyrosine kinase. HK-2 cells exposed to two different light chains upregulated c-Src activity, which increased the production of MCP-1. In parallel, we observed a time-dependent oxidation of c-Src. Inhibition of c-Src activity and silencing c-Src expression abrogated the light chain–induced MCP-1 response, but had no effect on H2O2, indicating that production of H2O2 is upstream of c-Src in the signaling cascade. Silencing megalin and cubilin expression inhibited the MCP-1 response, whereas extracellular catalase did not, indicating that endocytosis is required and that intracellular generation of reactive oxygen species activates c-Src. These data show that intracellular H2O2 induced by endocytosis of monoclonal free light chains oxidizes and activates c-Src, which promotes release of MCP-1. PMID:20558542

Basnayake, Kolitha; Ying, Wei-Zhong; Wang, Pei-Xuan

2010-01-01

64

Ultraviolet Light Induces Epidermal ornithine Decarboxylase Activity  

Microsoft Academic Search

Hairless mice were irradiated with fluorescent sun lamp tubes (peak emission at 313 nm). A significant increase in epidermal ornithine decarboxylase activity was found after 2 hr. A maximum 80-fold increase was found after 24 hr, decreasing again at 48 hr. Epidermal DNA synthesis was decreased at 6 hr and 24 hr increasing to a maximum 48 hr after irradiation.

Nicholas Lowe; Ajit K. Verma; Roswell K. Boutwell

1978-01-01

65

NATIONAL SYNCHROTRON LIGHT SOURCE ACTIVITY REPORT 1998  

Microsoft Academic Search

In FY 1998, following the 50th Anniversary Year of Brookhaven National Laboratory, Brookhaven Science Associates became the new Managers of BNL. The new start is an appropriate time to take stock of past achievements and to renew or confirm future goals. During the 1998 NSLS Annual Users Meeting (described in Part 3 of this Activity Report), the DOE Laboratory Operations

1999-01-01

66

DNA endonuclease activities on psoralen plus ultraviolet light treated DNA  

SciTech Connect

Activities of nuclear DNA endonucleases (Endos) from normal human lymphoblastoid cells on DNA treated with the DNA interstrand cross-linking agents 4,5'8-trimethyl psoralen (TMP) or 8-methoxypsoralen (MOP) plus long-wavelength (320-400 nm) ultraviolet light (UVA) were examined. Chromatin-associated DNA Endos were isolated from both cell lines and subjected to isoelectric focusing (IF). Each IF fraction was assayed for DNA Endo activity. Peaks of activity were pooled and assayed for activity on undamaged PM2 bacteriophage DNA and on PM2 DNA that had been treated with 15 ..mu..g/ml TMP or MOP in the dark and then exposed to UVA light. Unbound psoralen was removed by dialysis and a second dose of UVA light was given in order to increase the number of DNA cross-links. Two Endo activities were found which were active on TMP- and MOP-DNA: a major one, pI 4.6, which is also active on intercalated DNA, and a second, lesser one, pI 7.6, which is active on UVC (254 nm) light irradiated DNA. These results indicate that there are two different DNA Endos which act on both TMP- and MOP-treated DNA and that the major activity recognizes the intercalation of, and/or the cross-link produced by interaction of, psoralen with DNA.

Lambert, M.W.; Clark, M.

1986-03-01

67

Light-activated antibacterial surfaces comprise photosensitizers.  

PubMed

Antibacterial surfaces were prepared using a base polyethylene sheet topped with a layer containing a mixed powder of poly (vinylidene fluoride) and photosensitizers (PSs). A crimpled stamp was placed on the mixed powder, and then it was passed through a heating and pressing device. The three chosen PSs were rose bengal, toluidine blue O and methylene blue. Scanning electron microscope analysis showed that the PS surface texture was coarse and highly developed. Measurement of the apparent contact angles of the droplets deposited on the PS surfaces using goniometry showed that all three surfaces were hydrophobic. Photodynamic analysis of the surfaces into which the PSs were incorporated indicated significant reactive oxygen species formation after illumination with light fluency rate of 1.46 mW cm(-2) for 30 min. Photodynamic inactivation assays performed in nutrient broth demonstrated more than 4 log reduction of the attached Escherichia coli after illumination (1.46 mW cm(-2)) for 24 h when the inoculum was 10(3) CFU mL(-1). However, more than 4 log reduction of Staphylococcus aureus occurred even when the cultures were illuminated for only 6 h. Our results provide an inexpensive, simple, state-of-the-art method for preparing antibacterial surfaces that may help prevent infections in hospital surroundings and in some medical devices. PMID:21883241

Cahan, Rivka; Schwartz, Ronen; Langzam, Yakov; Nitzan, Yeshayahu

2011-01-01

68

A review on visible light active perovskite-based photocatalysts.  

PubMed

Perovskite-based photocatalysts are of significant interest in the field of photocatalysis. To date, several perovskite material systems have been developed and their applications in visible light photocatalysis studied. This article provides a review of the visible light (? > 400 nm) active perovskite-based photocatalyst systems. The materials systems are classified by the B site cations and their crystal structure, optical properties, electronic structure, and photocatalytic performance are reviewed in detail. Titanates, tantalates, niobates, vanadates, and ferrites form important photocatalysts which show promise in visible light-driven photoreactions. Along with simple perovskite (ABO3) structures, development of double/complex perovskites that are active under visible light is also reviewed. Various strategies employed for enhancing the photocatalytic performance have been discussed, emphasizing the specific advantages and challenges offered by perovskite-based photocatalysts. This review provides a broad overview of the perovskite photocatalysts, summarizing the current state of the work and offering useful insights for their future development. PMID:25532834

Kanhere, Pushkar; Chen, Zhong

2014-01-01

69

WindFloat: A floating foundation for offshore wind turbines  

Microsoft Academic Search

This manuscript summarizes the feasibility study conducted for the WindFloat technology. The WindFloat is a three-legged floating foundation for multimegawatt offshore wind turbines. It is designed to accommodate a wind turbine, 5 MW or larger, on one of the columns of the hull with minimal modifications to the nacelle and rotor. Potential redesign of the tower and of the turbine

Dominique Roddier; Christian Cermelli; Alexia Aubault; Alla Weinstein

2010-01-01

70

Ecological measurements of light exposure, activity, and circadian disruption  

PubMed Central

Circadian rhythms are biological rhythms that repeat at approximately 24 hours. In humans, circadian rhythms have an average period of 24.2 hours. The 24-hour patterns of light and dark on the retina synchronize circadian rhythms to the local time on earth. Lighting characteristics affecting circadian rhythms are very different than those affecting visual responses. Lack of synchronization between the endogenous clock and the local time has been associated with a host of maladies. Therefore, it is important to measure circadian light exposures over the course of the 24-hour day and to be able to assess circadian entrainment and disruption in actual living environments. Presented is an overview of the recently developed Daysimeter, a personal measurement device for recording activity and circadian light-exposure. When the Daysimeter is worn on the head, two light sensors near the eye are used to estimate circadian light (CLA) exposures over extended periods of time. Phasor analysis combines the measured periodic activity-rest patterns with the measured periodic light-dark patterns to assess behavioural circadian entrainment/disruption. As shown, day-shift and rotating-shift nurses exhibit remarkably different levels of behavioural circadian entrainment/disruption. These new ecological measurement and analysis techniques may provide important insights into the relationship between circadian disruption and well-being. PMID:23504497

Miller, D; Bierman, A; Figueiro, MG; Schernhammer, ES; Rea, MS

2013-01-01

71

Analysis of an Anomaly: The Increase in Time Float following Consumption  

PubMed Central

One fundamental axiom for project plan and schedule relates to the notion that time float will be reduced following its consumption. However, an anomalous scenario can emerge in which an activity's time float increases following its consumption. By exploring the associations between time float and paths in activity networks, we (a) reveal the conditions under which the anomaly occurs and (b) summarize laws related to total float. An activity's total float increases in parallel with its duration prolongation within a given boundary but remains constant or decreases in parallel with a prolongation outside the boundary. Furthermore, whereas a prolongation of an activity's duration in excess of classic total float does not delay project completion time, a lag of its start time to a degree slightly greater than the total float does. This analysis reveals different types of total float that correspond to different ways of usage. From this, we offer definitions for translation total float and prolongation total float that deviate from traditional conventions regarding the uniqueness of total float. PMID:25250376

Qi, Jianxun; Su, Zhixiong

2014-01-01

72

Ultraviolet B light stimulates hornet activities - a review  

NASA Astrophysics Data System (ADS)

For more than 30 years now, we have been gathering data on vespan activity in the field and laboratory under the influence of various factors. We found that light is most influential on the behaviour and activities of hornets (Hymenoptera, Vespinae); among various light wavelengths, the greatest influence was ascribed to the ultraviolet bandwidth (UVB). Prominent vespan activities outside their nest included digging, that is, the removal of soil from the nest, and we found this activity to take place at high noon, when the UV radiation, especially the UVB fraction, is maximal. In fact the digging activity of hornets was at times fully coordinated with the solar radiation, especially with the UVB portion of it, so that in daytime hours with diminished UV radiation, as in the morning or the afternoon, this activity and also flights outside the nest were accordingly curtailed, whereas at night there was no vespan flight at all. Under laboratory conditions, we found that hornets subjected to ether anaesthesia awaken faster when exposed to UV light than do control hornets left in the dark. In this connection, the exposure of pieces of hornet cuticle to UV light resulted in enhanced light absorption by the cuticle, but the absorption level reverted to normal after a period of rest in the dark. Tests for cuticular fluorescence after its irradiation with UVB light (290 nm) revealed a dominant emission in both UV and visible light. Furthermore, exposure of the cuticle of either live or dead hornets to light results in a photovoltaic effect which amplifies under UV irradiation. The hornet cuticle appears to behave like a semiconductor with traps and under the influence of light irradiation the electrical conductivity diminishes. The cuticle exposed to UV irradiation undergoes polarization, as do ferroelectric substances after being exposed to an electric field. The present paper summarizes the results of experiments and observations carried out on both live and dead hornets, from all of which emerges the conclusion that UV light is a factor which attracts hornets and influences them, while the hornets, in turn, utilize it for their own purposes. The latter utilization is achieved in cooperation with bacterial symbionts such as Staphylococcus xylosus and S. gallinarum.

Ishay, Jacob S.; Kirshboim, Shira

2000-07-01

73

Global Positioning System Synchronized Active Light Autonomous Docking System  

NASA Technical Reports Server (NTRS)

A Global Positioning System Synchronized Active Light Autonomous Docking System (GPSSALADS) for automatically docking a chase vehicle with a target vehicle comprising at least one active light emitting target which is operatively attached to the target vehicle. The target includes a three-dimensional array of concomitantly flashing lights which flash at a controlled common frequency. The GPSSALADS further comprises a visual tracking sensor operatively attached to the chase vehicle for detecting and tracking the target vehicle. Its performance is synchronized with the flash frequency of the lights by a synchronization means which is comprised of first and second internal clocks operatively connected to the active light target and visual tracking sensor, respectively, for providing timing control signals thereto, respectively. The synchronization means further includes first and second Global Positioning System receivers operatively connected to the first and second internal clocks, respectively, for repeatedly providing simultaneous synchronization pulses to the internal clocks, respectively. In addition, the GPSSALADS includes a docking process controller means which is operatively attached to the chase vehicle and is responsive to the visual tracking sensor for producing commands for the guidance and propulsion system of the chase vehicle.

Howard, Richard T. (Inventor); Book, Michael L. (Inventor); Bryan, Thomas C. (Inventor); Bell, Joseph L. (Inventor)

1996-01-01

74

Global Positioning System Synchronized Active Light Autonomous Docking System  

NASA Technical Reports Server (NTRS)

A Global Positioning System Synchronized Active Light Autonomous Docking System (GPSSALADS) for automatically docking a chase vehicle with a target vehicle comprises at least one active light emitting target which is operatively attached to the target vehicle. The target includes a three-dimensional array of concomitantly flashing lights which flash at a controlled common frequency. The GPSSALADS further comprises a visual tracking sensor operatively attached to the chase vehicle for detecting and tracking the target vehicle. Its performance is synchronized with the flash frequency of the lights by a synchronization means which is comprised of first and second internal clocks operatively connected to the active light target and visual tracking sensor, respectively, for providing timing control signals thereto, respectively. The synchronization means further includes first and second Global Positioning System receivers operatively connected to the first and second internal clocks, respectively, for repeatedly providing simultaneous synchronization pulses to the internal clocks, respectively. In addition, the GPSSALADS includes a docking process controller means which is operatively attached to the chase vehicle and is responsive to the visual tracking sensor for producing commands for the guidance and propulsion system of the chase vehicle.

Howard, Richard (inventor)

1994-01-01

75

The floating water bridge The floating water bridge  

E-print Network

properties and is also the reason why water must not be treated as a simple liquid [1,2]. The interactionThe floating water bridge The floating water bridge Elmar C. Fuchs1 , Jakob Woisetschläger2 , Karl ____________________________________________ Abstract When high voltage is applied to distilled water filled into two glass beakers which are in contact

Podgornik, Rudolf

76

Float level switch for a nuclear power plant containment vessel  

DOEpatents

This invention is a float level switch used to sense rise or drop in water level in a containment vessel of a nuclear power plant during a loss of coolant accident. The essential components of the device are a guide tube, a reed switch inside the guide tube, a float containing a magnetic portion that activates a reed switch, and metal-sheathed, ceramic-insulated conductors connecting the reed switch to a monitoring system outside the containment vessel. Special materials and special sealing techniques prevent failure of components and allow the float level switch to be connected to a monitoring system outside the containment vessel. 1 figures.

Powell, J.G.

1993-11-16

77

Light-activated electroluminescent switch with an active feedback circuit  

NASA Astrophysics Data System (ADS)

We describe an electroluminescent InP/InGaAsP p-n-p-n switch which can be optically activated. The high sensitivity exhibited by these devices eases the restriction of precise control of the bias voltage. Automatic resetting from the high-current ''on'' state to the initial ''off'' state is achieved with an active feedback circuit which utilizes a complementary metal-oxide semiconductor (CMOS) NAND gate and a monostable multivibrator. The best rise and fall times that we have observed are both about 150 ns. The recovery time is limited to approximately 600 ns by the fall time of the monostable multivibrator.

Campbell, J. C.; Qua, G. J.; Copeland, J. A.; Dentai, A. G.

1982-07-01

78

Selenium bond decreases ON resistance of light-activated switch  

NASA Technical Reports Server (NTRS)

Vitrified amorphous selenium bond decreases the ON resistance of a gallium arsenide-silicon light-activated, low-level switch. The switch is used under a pulse condition to prolong switch life and minimize errors due to heating, devitrification, and overdrawing.

1965-01-01

79

Active Galactic Nuclei Shed Light on Axionlike Particles  

SciTech Connect

We demonstrate that the scatter in the luminosity relations of astrophysical objects can be used to search for axionlike particles. This analysis is applied to observations of active galactic nuclei, where we find evidence highly suggestive of the existence of a very light axionlike particle.

Burrage, Clare [Theory Group, Deutsches Elektronen-Synchrotron DESY, D-22603 Hamburg (Germany); Davis, Anne-Christine [Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, Cambridge CB3 0WA (United Kingdom); Shaw, Douglas J. [Queen Mary University of London, Astronomy Unit, School of Mathematical Sciences, Mile End Road, London E1 4NS (United Kingdom)

2009-05-22

80

Azobenzene-based chloride transporters with light-controllable activities.  

PubMed

Synthetic chloride transporters containing two urea groups linked through a diazobenzene spacer have been prepared and the trans-to-cis isomerization by light stimulation results in dramatic changes in the chloride transport activities across lipid and cell membranes. PMID:25350406

Choi, Ye Rin; Kim, Gyu Chan; Jeon, Hae-Geun; Park, Jinhong; Namkung, Wan; Jeong, Kyu-Sung

2014-12-18

81

Floating natural gas liquefaction plant  

Microsoft Academic Search

Floating LNG plants offer a technically feasible and economical method to produce natural gas from marginal offshore fields and are under certain circumstances an economical alternative to land-based LNG plants. The presented floating, semisubmersible plant can keep up production under northern North Sea conditions all the year round.

Meyer-Detring

1977-01-01

82

Mirage of Floating Exchange Rates  

Microsoft Academic Search

This note summarizes some of the highlights of my longer paper with Guillermo Calvo”Fear of Floating.” Many emerging market countries have suffered financial crises. One view blames soft pegs for these crises. Adherents to that view suggest that countries move to corner solutions--hard pegs or floating exchange rates. We analyze the behavior of exchange rates, reserves, and interest rates to

Carmen M. Reinhart

2000-01-01

83

Promotion of sink activity of developing rose shoots by light.  

PubMed

Holding young rose shoots (Rosa hybrida cv. Marimba) in darkness while the rest of the plant was in light reduced the amount of (14)C assimilates recovered from the darkened shoot by half. Relative specific activity of the shoot tip grown in light was 13.5 times greater than that of the darkened one. The flower bud at the shoot tip degenerated in darkness and died. Shoots 2 to 3 centimeters long, after flower initiation, were most sensitive to the dark treatment. The degeneration is a gradual and reversible process in the first 8 days of darkness, followed by irreversible damage and atrophy. Darkening enhanced the ability of the young leaves to compete for the available assimilates over that of the darkened shoot tip. The enhancement of the mobilizing ability of the shoot tip by light is independent of photosynthesis since spraying with 3-(3,4-dichlorophenyl)-1,1-dimethylurea or holding shoots in a CO(2)-free atmosphere did not diminish the promoting effect of light on flower bud development or assimilate import. The possibility that light exerts its effect by photoproduction of ATP was also excluded inasmuch as no differences were found in ATP levels of shoot tips held in darkness and those held in light. PMID:16661566

Mor, Y; Halevy, A H

1980-11-01

84

Vitamin A activates rhodopsin and sensitizes it to ultraviolet light  

PubMed Central

The visual pigment, rhodopsin, consists of opsin protein with 11-cis retinal chromophore, covalently bound. Light activates rhodopsin by isomerizing the chromophore to the all-trans conformation. The activated rhodopsin sets in motion a biochemical cascade that evokes an electrical response by the photoreceptor. All-trans retinal is eventually released from the opsin and reduced to vitamin A. Rod and cone photoreceptors contain vast amounts of rhodopsin, so after exposure to bright light, the concentration of vitamin A can reach relatively high levels within their outer segments. Since a retinal analog, ?-ionone, is capable of activating some types of visual pigments, we tested whether vitamin A might produce a similar effect. In single-cell recordings from isolated dark-adapted salamander green-sensitive rods, exogenously applied vitamin A decreased circulating current and flash sensitivity and accelerated flash response kinetics. These changes resembled those produced by exposure of rods to steady light. Microspectrophotometric measurements showed that vitamin A accumulated in the outer segments and binding of vitamin A to rhodopsin was confirmed in in vitro assays. In addition, vitamin A improved the sensitivity of photoreceptors to ultraviolet (UV) light. Apparently, the energy of a UV photon absorbed by vitamin A transferred by a radiationless process to the 11-cis retinal chromophore of rhodopsin, which subsequently isomerized. Therefore, our results suggest that vitamin A binds to rhodopsin at an allosteric binding site distinct from the chromophore binding pocket for 11-cis retinal to activate the rhodopsin, and that it serves as a sensitizing chromophore for UV light. PMID:22192505

Miyazono, Sadaharu; Isayama, Tomoki; Delori, François C.; Makino, Clint L.

2013-01-01

85

Floating production systems  

SciTech Connect

The paper reviews the different types of floating production systems available to the petroleum industry and addresses why these platforms presently represent attractive candidates for future worldwide offshore Field developments. Attention is focused on tension leg platforms monohull production vessels and semisubmersible production platforms. The potential of new concepts such as the Spar platform are mentioned. Further, the paper focuses on important design features and engineering challenges for the various platform types. In order to highlight the global design aspects, both topside facilities and support structures as well as mooring systems, risers, subsea facilities and motion behavior are addressed, References to recent designs are made to illustrate the present state-of-the-art technology.

Moksnes, J.; Naess, T.; Eriksen, K.; Fjeld, S.

1995-12-31

86

Floating Silicon Method  

SciTech Connect

The Floating Silicon Method (FSM) project at Applied Materials (formerly Varian Semiconductor Equipment Associates), has been funded, in part, by the DOE under a “Photovoltaic Supply Chain and Cross Cutting Technologies” grant (number DE-EE0000595) for the past four years. The original intent of the project was to develop the FSM process from concept to a commercially viable tool. This new manufacturing equipment would support the photovoltaic industry in following ways: eliminate kerf losses and the consumable costs associated with wafer sawing, allow optimal photovoltaic efficiency by producing high-quality silicon sheets, reduce the cost of assembling photovoltaic modules by creating large-area silicon cells which are free of micro-cracks, and would be a drop-in replacement in existing high efficiency cell production process thereby allowing rapid fan-out into the industry.

Kellerman, Peter

2013-12-21

87

Floating on oil.  

PubMed

We demonstrate that disk-shaped steel meshes coated with a superamphiphobic layer are able to float on water and on organic liquids. A coated disk-shaped steel mesh of 1 cm radius has a loading capacity of 17 mN in water and still remarkable 9 mN in n-hexadecane. Experimentally measured supporting forces and loading capacities agree well with theoretical predictions. Inspired by the giant water lily, pan-shaped "oil lilies" with even higher loading capacity and artificial oil striders carrying more than 10 times their own weight are designed. Even after the artificial devices are fully immersed into different liquids, they show self-draining properties due to capillary forces. PMID:25109826

Zhang, Jihua; Deng, Xu; Butt, Hans-Jürgen; Vollmer, Doris

2014-09-01

88

Floating into Deep Space  

NASA Astrophysics Data System (ADS)

Is it possible for spaceflight to become more sustainable? Artist and architect Tomas Saraceno proposes a long-term artscience research project based on his initial work with solar balloons to join with the efforts of engineers such as John Powell, working on the Airship to Orbit experiments, which describe a three stage process of using airships to fly to a large suborbital "Dark Sky Station' then literally floating into orbit with additional electrical and chemical propulsion. (See: http://www.jpaerospace.com) In his artworks Tomás Saraceno proposes cell-like flying cities as possible architectonic living spaces in direct reference to Buckminster Fuller's Cloud Nine (circa 1960). The fantastic architectural utopia Cloud Nine consists of a freely floating sphere measuring one mile in diameter that offers living space to several autonomous communities encompassing thousands of inhabitants each. The notion of the cloud is essential to the artist's work. The cloud as metaphor stands for artistic intention, for the meaning of territory and border in today's (urban) society, and for exploring possibilities for the sustainable development of the human living environment. In Saraceno's work this environment is not limited to the earth, but is explicitly conceived to reach into outer space. (Biomimetic Constructions- On the works of Tomás Saraceno By Katharina Schlüter) Saraceno is also interested in human factors experiments using his existing constructions as analogue environments for living on Mars and is proposing carry out a series of workshops, experiments and solar balloon launces in White Sands desert in early 2016 in collaboration with the curator Dr Rob La Frenais, the Rubin Center at The University of Texas at El Paso and various scientific partners.

La Frenais, R.; Saraceno, T.; Powell, J.

2014-04-01

89

Surfaces of Rod Photoreceptor Light-activated Enzymes Disk Membranes  

Microsoft Academic Search

The light-activated GTP-binding protein (GBP) in toad rod outer segments has been located on the cytoplasmic surface (CS) of rod disk membranes by correlating biochemical results with images of quick-frozen, freeze-fractured, and deep-etched rod outer segments. This has been accomplished by selectively removing and replacing the 8-12-nm particles that are found on the CS of disk membranes, exactly in parallel

DOROTHY J. ROOF; JUAN I. KORENBROT; JOHN E. HEUSER

90

Acceptor impurity activation in III-nitride light emitting diodes  

NASA Astrophysics Data System (ADS)

In this work, the role of the acceptor doping and the acceptor activation and its impact on the internal quantum efficiency (IQE) of a Gallium Nitride (GaN) based multi-quantum well light emitting diode is studied by microscopic simulation. Acceptor impurities in GaN are subject to a high activation energy which depends on the presence of proximate dopant atoms and the electric field. A combined model for the dopant ionization and activation barrier reduction has been developed and implemented in a semiconductor carrier transport simulator. By model calculations, we demonstrate the impact of the acceptor activation mechanisms on the decay of the IQE at high current densities, which is known as the efficiency droop. A major contributor to the droop is the electron leakage which is largely affected by the acceptor doping.

Römer, Friedhard; Witzigmann, Bernd

2015-01-01

91

Temperature rise during experimental light-activated bleaching.  

PubMed

The purpose of this study was to evaluate the surface and intrapulpal temperatures after treatments with different bleaching gels subjected to different types of light activation. A K-type thermocouple and infrared thermometer were used to measure the temperature increase during the 15- or 30-min treatment period. Light-emitting diode with a center wavelength of 405 nm (LED405), organic light-emitting diode (OLED), and femtosecond laser were tested and compared to ZOOM2. The tooth surface was treated with five bleaching agents and Vaseline which served as a control.The generalized estimating equation (GEE) model was applied for testing the differences in temperature increase. The ZOOM2 light source led to the largest increase in mean pulpal and tooth surface temperatures of 21.1 and 22.8 °C, followed by focused femtosecond laser which increased the pulpal and surface temperatures by up to 15.7 and 16.8 °C. Treatments with unfocused femtosecond laser, LED405, and OLED induced significantly lower mean temperature increases (p?light activation, while LED405, OLED, and unfocused femtosecond laser could be safely used. PMID:23780710

Klaric, Eva; Rakic, Mario; Sever, Ivan; Tarle, Zrinka

2015-02-01

92

Vertical optical floating zone furnace: Principles of irradiation profile formation  

Microsoft Academic Search

The light distribution within the vertical double-ellipsoid mirror furnace applied for floating zone crystal growth with optical heating is studied. During the last few years, this setup was intensively applied for crystal growth of intermetallic and oxide materials due to its advantages for radiation focussing, which is superior in some key features compared to other commercial horizontal and vertical optical

D. Souptel; W. Löser; G. Behr

2007-01-01

93

Control development for floating wind  

NASA Astrophysics Data System (ADS)

Control of a floating wind turbine has proven to be challenging, but essential for lowering the cost of floating wind energy. Topic of a recent joint R&D project by GustoMSC, MARIN and ECN, is the concept design and verification with coupled simulations and model tests of the GustoMSC Tri-Floater. Only using an integral design approach, including mooring and control design, a cost effective system can be obtained. In this project, ECN developed a general floating wind turbine control strategy and applied this in a case study to the GustoMSC Tri-Floater and the OC3Hywind spar, both equipped with the NREL 5MW RWT. The designed controller ensures stable operation, while maintaining proper speed and power regulation. The motions of the floating support are reduced and substantial load reduction has been achieved.

Savenije, Feike; Peeringa, Johan

2014-06-01

94

Glucocorticoid receptor activity regulates light adaptation in the zebrafish retina.  

PubMed

Glucocorticoids modulate diverse aspects of physiology and behavior, including energy homeostasis, stress response, and memory, through activation of the glucocorticoid receptor (GR). Light perception has profound effects on the production of glucocorticoids via functional connections of the retina to the hypothalamus-pituitary-adrenal axis. We report here that glucocorticoids can also signal in the reverse direction, i. e., regulate visual function in zebrafish, Danio rerio. The zebrafish GR mutant, gr (s357) , harbors a missense mutation that completely blocks the transcriptional activity of GR. In this mutant, visual behavior was abolished following a period of darkness and recovered sluggishly after return to the light. Electrophysiological measurements showed that the photoresponse of the dark-adapted retina was reduced in the mutant and re-adapted to light with a substantial delay. Several gene products, including some that are important for dopaminergic signaling, were misregulated in gr (s357) mutants. We suggest that GR controls a gene network required for visual adaptation in the zebrafish retina and potentially integrates neuroendocrine and sensory responses to environmental changes. PMID:24068988

Muto, Akira; Taylor, Michael R; Suzawa, Miyuki; Korenbrot, Juan I; Baier, Herwig

2013-01-01

95

Glucocorticoid receptor activity regulates light adaptation in the zebrafish retina  

PubMed Central

Glucocorticoids modulate diverse aspects of physiology and behavior, including energy homeostasis, stress response, and memory, through activation of the glucocorticoid receptor (GR). Light perception has profound effects on the production of glucocorticoids via functional connections of the retina to the hypothalamus-pituitary-adrenal axis. We report here that glucocorticoids can also signal in the reverse direction, i. e., regulate visual function in zebrafish, Danio rerio. The zebrafish GR mutant, grs357, harbors a missense mutation that completely blocks the transcriptional activity of GR. In this mutant, visual behavior was abolished following a period of darkness and recovered sluggishly after return to the light. Electrophysiological measurements showed that the photoresponse of the dark-adapted retina was reduced in the mutant and re-adapted to light with a substantial delay. Several gene products, including some that are important for dopaminergic signaling, were misregulated in grs357 mutants. We suggest that GR controls a gene network required for visual adaptation in the zebrafish retina and potentially integrates neuroendocrine and sensory responses to environmental changes. PMID:24068988

Muto, Akira; Taylor, Michael R.; Suzawa, Miyuki; Korenbrot, Juan I.; Baier, Herwig

2013-01-01

96

Electrically floating, near vertical incidence, skywave antenna  

SciTech Connect

An Electrically Floating, Near Vertical Incidence, Skywave (NVIS) Antenna comprising an antenna element, a floating ground element, and a grounding element. At least part of said floating ground element is positioned between said antenna element and said grounding element. The antenna is separated from the floating ground element and the grounding element by one or more electrical insulators. The floating ground element is separated from said antenna and said grounding element by one or more electrical insulators.

Anderson, Allen A.; Kaser, Timothy G.; Tremblay, Paul A.; Mays, Belva L.

2014-07-08

97

Evaluation and floating enhancement of levodopa sustained release floating minitablets coated with insoluble acrylic polymer.  

PubMed

This article describes the in vitro evaluation and the enhancement of the floating properties of coated sustained release (SR) minitablets (MTs). The evaluated system consisted of a 3-mm drug-containing gas-generating core prepared by melt granulation and subsequent compression, which was then coated with a flexible polymeric membrane. Eudragit RL30D and acetyl triethylcitrate were used as a film former and a plasticizer, respectively. The coating level was fixed at 20% (wt/wt). The optimally coated floating MTs floated within 10 min and remained buoyant for more than 13 h, regardless of the pH of the test medium. By evaluating the dissolution profiles of levodopa at different pH, it was found that the release of levodopa was sustained for more than 12 h regardless of the pH, even if the coating did not cancel the effect of the pH-dependent solubility of the active drug. Finally, the robustness of the coated floating MTs was assessed by testing the drug release variability in function of the stirring conditions during dissolution tests. PMID:18618310

Goole, J; Amighi, K; Vanderbist, F

2008-08-01

98

Slow-light-enhanced gain in active photonic crystal waveguides.  

PubMed

Passive photonic crystals have been shown to exhibit a multitude of interesting phenomena, including slow-light propagation in line-defect waveguides. It was suggested that by incorporating an active material in the waveguide, slow light could be used to enhance the effective gain of the material, which would have interesting application prospects, for example enabling ultra-compact optical amplifiers for integration in photonic chips. Here we experimentally investigate the gain of a photonic crystal membrane structure with embedded quantum wells. We find that by solely changing the photonic crystal structural parameters, the maximum value of the gain coefficient can be increased compared with a ridge waveguide structure and at the same time the spectral position of the peak gain be controlled. The experimental results are in qualitative agreement with theory and show that gain values similar to those realized in state-of-the-art semiconductor optical amplifiers should be attainable in compact photonic integrated amplifiers. PMID:25266779

Ek, Sara; Lunnemann, Per; Chen, Yaohui; Semenova, Elizaveta; Yvind, Kresten; Mork, Jesper

2014-01-01

99

Active dielectric antenna on chip for spatial light modulation.  

PubMed

Integrated photonic resonators are widely used to manipulate light propagation in an evanescently-coupled waveguide. While the evanescent coupling scheme works well for planar optical systems that are naturally waveguide based, many optical applications are free-space based, such as imaging, display, holographics, metrology and remote sensing. Here we demonstrate an active dielectric antenna as the interface device that allows the large-scale integration capability of silicon photonics to serve the free-space applications. We show a novel perturbation-base diffractive coupling scheme that allows a high-Q planer resonator to directly interact with and manipulate free-space waves. Using a silicon-based photonic crystal cavity whose resonance can be rapidly tuned with a p-i-n junction, a compact spatial light modulator with an extinction ratio of 9.5 dB and a modulation speed of 150 MHz is demonstrated. Method to improve the modulation speed is discussed. PMID:23152946

Qiu, Ciyuan; Chen, Jianbo; Xia, Yang; Xu, Qianfan

2012-01-01

100

Active dielectric antenna on chip for spatial light modulation  

PubMed Central

Integrated photonic resonators are widely used to manipulate light propagation in an evanescently-coupled waveguide. While the evanescent coupling scheme works well for planar optical systems that are naturally waveguide based, many optical applications are free-space based, such as imaging, display, holographics, metrology and remote sensing. Here we demonstrate an active dielectric antenna as the interface device that allows the large-scale integration capability of silicon photonics to serve the free-space applications. We show a novel perturbation-base diffractive coupling scheme that allows a high-Q planer resonator to directly interact with and manipulate free-space waves. Using a silicon-based photonic crystal cavity whose resonance can be rapidly tuned with a p-i-n junction, a compact spatial light modulator with an extinction ratio of 9.5?dB and a modulation speed of 150?MHz is demonstrated. Method to improve the modulation speed is discussed. PMID:23152946

Qiu, Ciyuan; Chen, Jianbo; Xia, Yang; Xu, Qianfan

2012-01-01

101

Skylab floating ice experiment  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. Coupling of the aircraft data with the ground truth observations proved to be highly successful with interesting results being obtained with IR and SLAR passive microwave techniques, and standard photography. Of particular interest were the results of the PMIS system which operated at 10.69 GHz with both vertical and horizontal polarizations. This was the first time that dual polarized images were obtained from floating ice. In both sea and lake ice, it was possible to distinguish a wide variety of thin ice types because of their large differences in brightness temperatures. It was found that the higher brightness temperature was invariably obtained in the vertically polarized mode, and as the age of the ice increases the brightness temperature increases in both polarizations. Associated with this change in age, the difference in temperature was observed as the different polarizations decreased. It appears that the horizontally polarized data is the most sensitive to variations in ice type for both fresh water and sea ice. The study also showed the great amount of information on ice surface roughness and deformation patterns that can be obtained from X-band SLAR observations.

Campbell, W. J. (principal investigator); Ramseier, R. O.; Weaver, R. J.; Weeks, W. F.

1975-01-01

102

Circadian phagocytic activity in rats under light-dark and constant light regimens.  

PubMed

The phagocytic function was proved to be a periodic, circadian process. Its acrophase appears to be differently timed in species with different activity type, occurring in the evening in diurnal species and at night in nocturnal ones. The main pineal hormone melatonin, whose secretion occurs strictly at dark, has been shown to play a role in the control of inflammation and to exert a certain stimulatory effect upon phagocytosis in vitro. The aim of the present study was to assess whether the phagocytic activity of neutrophils in the blood of rats exhibits a circadian rhythmicity similar to that of other nocturnal rodents (mice) and also if a constant light regimen alters its amplitude and/or chronostructure. Wistar rats were submitted to either an artificial light-dark 12/12 regimen (LD) or to constant light (LL), for 15 days. In vitro phagocytosis of the neutrophils in whole blood against E.coli was assessed at 10:00, 16:00, 22:00, and 04:00 hours. In LD, phagocytosis appears to be a rhythmical function, with statistically significant differences between the highest value at 04:00 hrs and the lowest at 10:00 hrs. Constant light induces a 30% depression of the phagocytic ability throughout the whole 24 hours cycle, without altering its oscillations. The darkness period appears to play the role of a synchronizer; in its absence the rhythm tends to free-run. It may be stated that rhythmical melatonin secretion is responsible only for maintenance of the phagocytic level, probably via the anterior hypothalamic area and thymus, while it cannot account directly for the nocturnal increase of phagocytosis. PMID:15984664

Hriscu, Monica; Saulea, Gabriela; Ostriceanu, Simfora; Baciu, I

103

Design, Synthesis, and Monitoring of Light-Activated Motorized Nanomachines  

NASA Astrophysics Data System (ADS)

Our group has developed a family of single molecules termed nanocars, which are aimed at performing controllable motion on surfaces. In this work, a series of light-activated motorized nanomachines incorporated with a MHz frequency light-activated unidirectional rotary motor were designed and synthesized. We hope the light-activated motor can serve as the powering unit for the nanomachines, and perform controllable translational motion on surfaces or in solution. A series of motorized nanovehicles intended for scanning tunneling microscopy (STM) imaging were designed and synthesized. A p-carborane-wheeled motorized nanocar was synthesized and monitored by STM. Single-molecule imaging was accomplished on a Cu(111) surface. However, further manipulations did lead to motor induced lateral motion. We attributed this result to the strong molecule-surface interactions between the p-carborane-wheeled nanocar and the Cu(111) surface and possible energy transfer between the rotary motor and the Cu(111) surface. To fine-tune the molecule-surface interactions, an adamantane-wheeled motorized nanocar and a three-wheel nanoroadster were designed and synthesized. In addition, the STM substrates will be varied and different combinations of molecule-surface interactions will be studied. As a complimentary imaging method to STM, single-molecule fluorescence microscopy (SMFM) also provides single-molecule level resolution. Unlike STM experiment requires ultra-high vacuum and conductive substrate, SMFM experiment is conducted at ambient conditions and uses non-conductive substrate. This imaging method allows us to study another category of molecule-surface interactions. We plan to design a fluorescent motorized nanocar that is suitable for SMFM studies. However, both the motor and fluorophore are photochemically active molecules. In proximity, some undesired energy transfer or interference could occur. A cyanine 5- (cy5-) tagged motorized nanocar incorporated with the MHz motor was designed and synthesized in order to minimize the potential energy transfer or interference between the motor and the fluorophore. The SMFM study of this cy5-tagged motorized nanocar is currently undergoing. The design of light-activated motorized nanocar inspired the design of nanosubmarines. We used fluorescence quenching and fluorescence correlation spectroscopy (FCS) to study the diffusion of single molecules. The fluorescence quenching experiments of Ru(bpy)3+2 by a quenching nanosubmarine was conducted, but no motor induced acceleration of the molecule were observed. Another fluorescent nanosubmarine was monitored by FCS, and no increase of diffusion coefficient was found. Finally, a 1-D channel approach was adopted for decreasing the effects of Brownian motion, and acceleration of nanosubmarine was observed.

Chiang, Pinn-Tsong

104

Floating intake reduces pump damage  

SciTech Connect

The solution to a costly sand erosion problem at the Grande Dixence hydroelectric project in Switzerland turned out to be as simple as a floating pump. The 726-MW Grande Dixence project drains a 350-square-kilometer reach of the Zermatt and Herens valleys in the southwestern Swiss Alps. About half of the drainage area is covered by active glaciers. Because the glaciers in Zermatt Valley are so low in altitude, their water is collected in Z`mutt Reservoir at the base of the Matterhorn, then pumped up 500 meters for transport to the main Grande Disence Reservoir near Sion. The glacier water is heavily laden with sand. In spite of a gravel pass and a desilter, the 700,000-acubic-meter Z`mutt Reservoir receives large quantities of sand. The sand tends to remain in solution because of the low water temperatures (1 to 2 degrees Centigrade). In the original intake system, the sand would be sucked into the pump intakes, causing extensive erosion to the pump wheels and an expensive yearly program of repair. (Pump damage averaged 200,000 Swiss Francs ($284,000 U.S.) per year between 1980 and 1985.)

Kronig, A.

1993-12-31

105

Vertical optical floating zone furnace: Principles of irradiation profile formation  

NASA Astrophysics Data System (ADS)

The light distribution within the vertical double-ellipsoid mirror furnace applied for floating zone crystal growth with optical heating is studied. During the last few years, this setup was intensively applied for crystal growth of intermetallic and oxide materials due to its advantages for radiation focussing, which is superior in some key features compared to other commercial horizontal and vertical optical floating zone facilities. A point source model was used as a light source to reveal basic principles of the irradiation profile formation, which can strongly affect the melt flows, as well as the curvature and stability of crystallization front. Effects of the lamp displacement along the vertical optical axis with respect to the focal point of the lower elliptical mirror and the effect of mirror apertures were studied as the prime factors, which determine the light profile on the crystal. The efficiency of the light focusing in the presented optical configuration is discussed.

Souptel, D.; Löser, W.; Behr, G.

2007-03-01

106

Asymmetric photoredox transition-metal catalysis activated by visible light  

NASA Astrophysics Data System (ADS)

Asymmetric catalysis is seen as one of the most economical strategies to satisfy the growing demand for enantiomerically pure small molecules in the fine chemical and pharmaceutical industries. And visible light has been recognized as an environmentally friendly and sustainable form of energy for triggering chemical transformations and catalytic chemical processes. For these reasons, visible-light-driven catalytic asymmetric chemistry is a subject of enormous current interest. Photoredox catalysis provides the opportunity to generate highly reactive radical ion intermediates with often unusual or unconventional reactivities under surprisingly mild reaction conditions. In such systems, photoactivated sensitizers initiate a single electron transfer from (or to) a closed-shell organic molecule to produce radical cations or radical anions whose reactivities are then exploited for interesting or unusual chemical transformations. However, the high reactivity of photoexcited substrates, intermediate radical ions or radicals, and the low activation barriers for follow-up reactions provide significant hurdles for the development of efficient catalytic photochemical processes that work under stereochemical control and provide chiral molecules in an asymmetric fashion. Here we report a highly efficient asymmetric catalyst that uses visible light for the necessary molecular activation, thereby combining asymmetric catalysis and photocatalysis. We show that a chiral iridium complex can serve as a sensitizer for photoredox catalysis and at the same time provide very effective asymmetric induction for the enantioselective alkylation of 2-acyl imidazoles. This new asymmetric photoredox catalyst, in which the metal centre simultaneously serves as the exclusive source of chirality, the catalytically active Lewis acid centre, and the photoredox centre, offers new opportunities for the `green' synthesis of non-racemic chiral molecules.

Huo, Haohua; Shen, Xiaodong; Wang, Chuanyong; Zhang, Lilu; Röse, Philipp; Chen, Liang-An; Harms, Klaus; Marsch, Michael; Hilt, Gerhard; Meggers, Eric

2014-11-01

107

Light Activated Serotonin for Exploring Its Action in Biological Systems  

PubMed Central

Summary Serotonin (5-HT) is a neuromodulator involved in regulating mood, appetite, memory, learning, pain, and establishment of left-right (LR) asymmetry in embryonic development. To explore the role of 5-HT in a variety of physiological contexts, we have created two forms of “caged” 5-HT, BHQ-O-5HT and BHQ-N-5HT. When exposed to 365- or 740-nm light, BHQ-O-5HT releases 5-HT through 1- or 2-photon excitation, respectively. BHQ-O-5HT mediated changes in neural activity in cultured primary sensory neurons from mouse and the trigeminal ganglion and optic tectum of intact zebrafish larvae in the form of high amplitude spiking in response to light. In Xenopus laevis embryos, 5-HT released from BHQ-O-5HT upon exposure to light increased the occurrence of LR patterning defects. Maximal rates of LR defects were observed when 5-HT was released at stage 5 compared to stage 8. These experiments show the potential for BHQ-caged serotonins in studying 5-HT-regulated physiological processes. PMID:24333002

Rea, Adam C.; Vandenberg, Laura N.; Ball, Rebecca E.; Snouffer, Ashley A.; Hudson, Alicia G.; Zhu, Yue; McLain, Duncan E.; Johnston, Lindsey L.; Lauderdale, James D.; Levin, Michael; Dore, Timothy M.

2013-01-01

108

Illinois PER Interactive Examples: Floating Cylinders  

NSDL National Science Digital Library

This is an interactive homework problem for introductory physics students relating to fluids and buoyant force. It involves two differently shaped cylinders with the same mass density floating in a container of non-moving water. The student must determine the ratio of the height of Cylinder #2 above the water to the height of Cylinder #1 above the water. A user-activated "help" sequence is provided for each step of the problem-solving, from conceptual analysis through quantitative calculation. To promote critical thinking, immediate feedback is received for both correct and incorrect responses. This item is part of a larger collection of interactive homework problems for introductory physics.

Gladding, Gary

2008-09-10

109

Tried and True: Whatever floats your boat  

NSDL National Science Digital Library

Ever since Archimedes ran down the streets of ancient Greece shouting, "Eureka!," scientists have understood that a submerged body displaces a volume of water equalto its own volume. Scientists also came to realize that if a body weighed less than the water it displaced, the body would float. Although this knowledge has been aroundfor nearly 2,500 years, many students still have difficulty explaining how a vessel made of a heavier-than-water material, such as steel, remains afloat. The following triedand true activity provides students with a hands-on experience that explains the principle of buoyancy.

Mcbride, Susan L.

2003-03-01

110

Clinical Features: Patients with Floating Harbor syndrome [OMIM #136140] typically have short stature, delayed osseous  

E-print Network

Activator Protein, Cause Floating Harbor Syndrome." (2012) Am J Hum Genet 90(2): 308-313. 2. White S et al1/13 Clinical Features: Patients with Floating Harbor syndrome [OMIM #136140] typically have short of affected individuals include a triangular shaped face, short philtrum, wide mouth, and a long nose

Ober, Carole

111

Optimization of float use in risk analysis-based network scheduling  

Microsoft Academic Search

Floats are often used in project networks for resource allocations and as an alternative for reducing project costs without causing negative impact on project duration. However, when the time uncertainties of non-critical activities are great, the use of floats can lead to an increased risk of project schedule overruns, and accordingly an increase in project costs. This paper presents a

Daji Gong

1997-01-01

112

14 CFR 29.521 - Float landing conditions.  

Code of Federal Regulations, 2012 CFR

...Requirements Water Loads § 29.521 Float landing conditions. If certification for float operation (including float amphibian operation) is requested, the rotorcraft, with floats, must be designed to withstand the following loading...

2012-01-01

113

14 CFR 29.521 - Float landing conditions.  

Code of Federal Regulations, 2013 CFR

...Requirements Water Loads § 29.521 Float landing conditions. If certification for float operation (including float amphibian operation) is requested, the rotorcraft, with floats, must be designed to withstand the following loading...

2013-01-01

114

14 CFR 29.521 - Float landing conditions.  

Code of Federal Regulations, 2014 CFR

...Requirements Water Loads § 29.521 Float landing conditions. If certification for float operation (including float amphibian operation) is requested, the rotorcraft, with floats, must be designed to withstand the following loading...

2014-01-01

115

14 CFR 29.521 - Float landing conditions.  

Code of Federal Regulations, 2011 CFR

...Requirements Water Loads § 29.521 Float landing conditions. If certification for float operation (including float amphibian operation) is requested, the rotorcraft, with floats, must be designed to withstand the following loading...

2011-01-01

116

14 CFR 29.521 - Float landing conditions.  

Code of Federal Regulations, 2010 CFR

...Requirements Water Loads § 29.521 Float landing conditions. If certification for float operation (including float amphibian operation) is requested, the rotorcraft, with floats, must be designed to withstand the following loading...

2010-01-01

117

Airship-floated wind turbine  

SciTech Connect

A wind turbine, by use of a tethered airship for support, may be designed for the economical recovery of power at heights of 2,000 feet or more above ground, at which height power density in the wind is typically three times the power density available to a conventionally supported wind turbine. Means can be added to such an airship-floated wind turbine which will permit its generators to be used to meet load demand even during periods of little or no wind. Described to this end is a wind turbine system which combines, among other novel features: a novel tether line system which provides access for men and materials to the supporting airship while in active service, a novel system for providing additional buoyant lift at the nose of the turbine-supporting airship to offset the vertical component of tension induced in the tether line by the downwind force exerted by the turbine blades, a novel bearing assembly at the nose of the supporting airship which permits the airship to rotate as a unit with the turbine it supports without causing a similar rotation of the tether line, a novel turbine airship structure which handles concentrated loads from the turbine efficiently and also permits the safe use of hydrogen for buoyancy, a novel ''space frame'' structure which supports the turbine blades and greatly reduces blade weight, a novel system for controlling turbine blade angle of incidence and for varying blade incidene in synchrony with blade angular position abut the turbine axis to provide greater control over airship movement, a novel system for locating propellor-driven generators out at the wind turbine perimeter and for using lightweight, high-RPM generators to produce electrical energy at a power line frequency, which greatly reduces the weight required to convert turbine blade torque into useful power, and a novel system for incorporating compressed air storage and combustion turbine components into the wind turbine's generator drive systems.

Watson, W. K.

1985-01-01

118

Light activation of protein splicing with a photocaged fast intein.  

PubMed

Intein-mediated protein splicing has found broad biotechnological applications. Herein, we describe our recent result in engineering a photoactivatable intein compatible with living mammalian cells. A photocaged cysteine amino acid residue was genetically introduced into a highly efficient Nostoc punctiforme (Npu) DnaE intein. The resulting photocaged intein was inserted into a red fluorescent protein (RFP) mCherry and a human Src tyrosine kinase to create inactive chimeric proteins. A light-induced photochemical reaction was able to reactivate the intein and trigger protein splicing. Active mCherry and Src were formed as observed by direct fluorescence imaging or imaging of an Src kinase sensor in mammalian cells. The genetically encoded photocaged intein is a general optogenetic tool, allowing effective photocontrol of primary structures and functions of proteins. PMID:25647354

Ren, Wei; Ji, Ao; Ai, Hui-Wang

2015-02-18

119

Floating ports: Design and construction practices  

SciTech Connect

This book is a guide to designing and constructing floating piers, wharves, docks, mooring systems, and small craft marinas. It presents engineering fundamentals and techniques. After a general introduction to floating marine terminals, the book discusses design loads and forces, and examines floating pier design requirements and considerations. Buoyancy and stability of various floating designs are discussed in detail, along with mooring systems and approach bridges. The concluding chapter contains case histories.

Tsinker, G.P.

1986-01-01

120

The fluid mechanics of floating and sinking  

E-print Network

objects can float at an interface between two fluids. We obtain the conditions on density and size for various objects to float and show that being ‘super-hydrophobic’ does not generally help small, dense objects to float. Super-hydrophobicity does...

Vella, Dominic Joseph Robert

2007-10-02

121

Tunable conductivity and conduction mechanism in an ultraviolet light activated electronic conductor  

E-print Network

Tunable conductivity and conduction mechanism in an ultraviolet light activated electronic of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208 Kenneth R. Poeppelmeier May 2005 A tunable conductivity has been achieved by controllable substitution of an ultraviolet light

Medvedeva, Julia E.

122

Some Activities with Polarized Light from a Laptop LCD Screen  

ERIC Educational Resources Information Center

The LCD screen of a laptop computer provides a broad, bright, and extended source of polarized light. A number of demonstrations on the properties of polarized light from a laptop computer screens are presented here.

Fakhruddin, Hasan

2008-01-01

123

Stem cell activation by light guides plant organogenesis  

E-print Network

in the light, an effect that is mediated through the plant hormone cytokinin. Dark treatment also affects-inducible meristem growth toward organ formation. In contrast to common wisdom over the last 150 years, the light. [Keywords: light signaling; stem cells; organ initiation; cytokinin; auxin; shoot apical meristem

Kuhlemeier, Cris

124

Will My Fossil Float?  

ERIC Educational Resources Information Center

Explains how young students can be introduced to fossils. Suggests books to read and science activities including "Fossils to Eat" where students make fossils from peanut butter, honey, and powdered milk. (PR)

Riesser, Sharon; Airey, Linda

1993-01-01

125

Phytoremediation of perchlorate by free floating macrophytes.  

PubMed

Phytoremediation of perchlorate by free floating macrophytes (Eichornia, Pistia, Salvinia and Lemna) was evaluated in this study. Among the plants tested, Pistia showed 63.8 ± 4% (w/v) removal of 5 mg/L level perchlorate in 7 days, whereas the removal was absent in other plants. Phyto-accumulation (18.2%) and rhizo-degradation (45.68%) were identified as the mechanisms involved in perchlorate removal in Pistia. Whole plant extraction yielded 45.4 ?g perchlorate/g dry weight biomass in 7 days period. High intensity of light and presence of nitrate negatively affected perchlorate removal by Pistia. An enrichment of Pistia root homogenate exhibited faster reduction of perchlorate where 100mg/L of the compound was reduced completely in 48 h under anoxic condition. A novel perchlorate reducing bacterium, isolated from Pistia root homogenate enrichment was identified as Acinetobacter sp. NIIST (Genbank JX467695). PMID:23872336

Bhaskaran, Krishnakumar; Vijaya Nadaraja, Anupama; Tumbath, Soumya; Babu Shah, Liji; Gangadharan Puthiya Veetil, Prajeesh

2013-09-15

126

Floating and Falling Flows  

NSDL National Science Digital Library

Learners create beautiful fluid motion. They explore fluid dynamics, surface tension, solubility, and buoyancy while mixing liquids together. Learners can photograph or film the fluid motion for analysis as well. This activity is also suitable as a demonstration. Learners can continue their investigations by completing the related activity "Density Rainbow and the Great Viscosity Race." Resource contains vocabulary definitions, detailed background information, and suggestions for assessment and extensions.

Taylor, Cody; Camacho, Gala; Hertzberg, Jean; Zarske, Malinda S.; Carlson, Denise

2006-01-01

127

Balloons and Other Things That Sometimes Float  

NSDL National Science Digital Library

Hot air balloons float--sometimes. Regular old balloons that you get at a party float--sometimes. Boats float--sometimes. What makes them float and what makes them sink? How can a boat made of steel float but a solid chunk of steel sink to the bottom of the ocean? Part of the answer has to do with something called density, which will be discussed in this chapter. And yes, the concepts addressed in this chapter do have a lot to do with weather.

2005-01-01

128

Exogenous control of diel locomotor activity in the whitefish Coregonus clupeaformis: effects of light and temperature  

Microsoft Academic Search

Data on factors determining activity cycles of nearctic fishes are scarce overall, and nonexistent for Coregoniae (family Salmonidae), a group with closely related and somewhat better known palaearctic species. We studied effects of photoperiodicity, light intensity and temperature on diel locomotor activity of lake whitefish Coregonus clupeaformis (Mitchill). Under LD 12:12, a day-active pattern was evident. Under continuous light (LL)

E. Scherer; S. E. Harrison

1988-01-01

129

Active Matrix Organic Light Emitting Diode (AMOLED) Environmental Test Report  

NASA Technical Reports Server (NTRS)

This report focuses on the limited environmental testing of the AMOLED display performed as an engineering evaluation by The NASA Johnson Space Center (JSC)-specifically. EMI. Thermal Vac, and radiation tests. The AMOLED display is an active-matrix Organic Light Emitting Diode (OLED) technology. The testing provided an initial understanding of the technology and its suitability for space applications. Relative to light emitting diode (LED) displays or liquid crystal displays (LCDs), AMOLED displays provide a superior viewing experience even though they are much lighter and smaller, produce higher contrast ratio and richer colors, and require less power to operate than LCDs. However, AMOLED technology has not been demonstrated in a space environment. Therefore, some risks with the technology must be addressed before they can be seriously considered for human spaceflight. The environmental tests provided preliminary performance data on the ability of the display technology to handle some of the simulated induced space/spacecraft environments that an AMOLED display will see during a spacecraft certification test program. This engineering evaluation is part of a Space Act Agreement (SM) between The NASA/JSC and Honeywell International (HI) as a collaborative effort to evaluate the potential use of AMOLED technology for future human spaceflight missions- both government-led and commercial. Under this SM, HI is responsible for doing optical performance evaluation, as well as temperature and touch screen studies. The NASA/JSC is responsible for performing environmental testing comprised of EMI, Thermal Vac, and radiation tests. Additionally, as part of the testing, limited optical data was acquired to assess performance as the display was subjected to the induced environments. The NASA will benefit from this engineering evaluation by understanding AMOLED suitability for future use in space as well as becoming a smarter buyer (or developer) of the technology. HI benefits from the environmental testing results by understanding its performance limitations/shortcomings to improve subsequent generations of AMOLED technology. Note that the AMOLED used in this test was not deSigned for the space environment but rather for commercial/industrial terrestrial applications.

Salazar, George A.

2013-01-01

130

Temporal and spatial distribution of floating objects in coastal waters of central-southern Chile and Patagonian fjords  

NASA Astrophysics Data System (ADS)

Floating objects are suggested to be the principal vector for the transport and dispersal of marine invertebrates with direct development as well as catalysts for carbon and nutrient recycling in accumulation areas. The first step in identifying the ecological relevance of floating objects in a specific area is to identify their spatio-temporal distribution. We evaluated the composition, abundance, distribution, and temporal variability of floating objects along the continental coast of central-southern Chile (33-42°S) and the Patagonian fjords (42-50°S) using ship surveys conducted in austral winter (July/August) and spring (November) of the years 2002-2005 and 2008. Potential sources of floating items were identified with the aid of publicly available databases and scientific reports. We found three main types of floating objects, namely floating marine debris (mainly plastic objects and Styrofoam), wood (trunks and branches), and floating kelps ( Macrocystis pyrifera and Durvillaea antarctica). Floating marine debris were abundant along most of the examined transects, with markedly lower abundances toward the southern fjord areas. Floating marine debris abundances generally corresponded to the distribution of human activities, and were highest in the Interior Sea of Chiloé, where aquaculture activities are intense. Floating wood appeared sporadically in the study area, often close to the main rivers. In accordance with seasonal river run-off, wood was more abundant along the continental coast in winter (rainy season) and in the Patagonian fjords during the spring surveys (snow melt). Densities of the two floating kelp species were similar along the continental coast, without a clear seasonal pattern. M. pyrifera densities increased towards the south, peaking in the Patagonian fjords, where it was dominant over D. antarctica. Densities of M. pyrifera in the Patagonian fjords were highest in spring. Correlation analyses between the abundances of floating objects and the distance to the nearest sources were generally non-significant, suggesting that post-supply processes affect the distribution of the floating objects in the study region. The identification of several major retention zones supports this idea. Accumulation areas of floating objects appear to be more common in the fjord zones. In general, the results underscore the abundance of floating objects throughout the study region and the fact that floating marine debris sources are mostly local, whereas floating algae may be dispersed over greater distances. Future studies should focus on the ecological role of floating objects in biota dispersal and nutrient cycling.

Hinojosa, Iván A.; Rivadeneira, Marcelo M.; Thiel, Martin

2011-03-01

131

Engineering of a red-light-activated human cAMP/cGMP-specific phosphodiesterase.  

PubMed

Sensory photoreceptors elicit vital physiological adaptations in response to incident light. As light-regulated actuators, photoreceptors underpin optogenetics, which denotes the noninvasive, reversible, and spatiotemporally precise perturbation by light of living cells and organisms. Of particular versatility, naturally occurring photoactivated adenylate cyclases promote the synthesis of the second messenger cAMP under blue light. Here, we have engineered a light-activated phosphodiesterase (LAPD) with complementary light sensitivity and catalytic activity by recombining the photosensor module of Deinococcus radiodurans bacterial phytochrome with the effector module of Homo sapiens phosphodiesterase 2A. Upon red-light absorption, LAPD up-regulates hydrolysis of cAMP and cGMP by up to sixfold, whereas far-red light can be used to down-regulate activity. LAPD also mediates light-activated cAMP and cGMP hydrolysis in eukaryotic cell cultures and in zebrafish embryos; crucially, the biliverdin chromophore of LAPD is available endogenously and does not need to be provided exogenously. LAPD thus establishes a new optogenetic modality that permits light control over diverse cAMP/cGMP-mediated physiological processes. Because red light penetrates tissue more deeply than light of shorter wavelengths, LAPD appears particularly attractive for studies in living organisms. PMID:24889611

Gasser, Carlos; Taiber, Sandra; Yeh, Chen-Min; Wittig, Charlotte Helene; Hegemann, Peter; Ryu, Soojin; Wunder, Frank; Möglich, Andreas

2014-06-17

132

Float Zone Experiments in Space  

NASA Technical Reports Server (NTRS)

The objective of this work has been to evaluate whether or not Marangoni flow could be suppressed in molten metals by the presence of very thin oxide films. Experimental work has been carried out on molten Sn under UHV conditions. A disk floating zone arrangement was developed to allow in situ Auger examination of molten surfaces. An electron energy loss technique was developed which allows detection of continuous tin oxide films of 6 A or greater. Experiments were planned to detect the effects of oxide formation upon Marangoni flow by measuring: (1) temperature profiles, (2) solid liquid interface shapes, (3) macrosegregation, and (4) the onset of oscillatory Marangoni flow by detecting oscillating temperature variations. Work on (4) showed that oscillatory temperature variations of frequency or = 10 Hz were not present in the disk float zone geometry under conditions of Ma = 4300 with an oxide free molten surface. The disk float zone geometry was modeled with a finite element analysis and temperature and velocity profiles were determined.

Verhoeven, J. D.

1985-01-01

133

Float zone experiments in space  

NASA Technical Reports Server (NTRS)

The molten zone/freezing crystal interface system and all the mechanisms were examined. If Marangoni convection produces oscillatory flows in the float zone of semiconductor materials, such as silicon, then it is unlikely that superior quality crystals can be grown in space using this process. The major goals were: (1) to determine the conditions for the onset of Marangoni flows in molten tin, a model system for low Prandtl number molten semiconductor materials; (2) to determine whether the flows can be suppressed by a thin oxide layer; and (3) based on experimental and mathematical analysis, to predict whether oscillatory flows will occur in the float zone silicon geometry in space, and if so, could it be suppressed by thin oxide or nitride films. Techniques were developed to analyze molten tin surfaces in a UHV system in a disk float zone geometry to minimize buoyancy flows. The critical Marangoni number for onset of oscillatory flows was determined to be greater than 4300 on atomically clean molten tin surfaces.

Verhoeven, J. D.; Noack, M. A.; Gill, W. N.; Hau, C. C.

1984-01-01

134

Physiological relevant in vitro evaluation of polymer coats for gastroretentive floating tablets.  

PubMed

Gastroretentive drug delivery systems are retained in the stomach for a sufficient time interval, releasing the drug in a controlled manner. According to literature, the floating principle is the most frequently used formulation approach for gastric retention. However, many publications lack information of the floating forces, the impact of different pH-values and almost no information exist concerning the resistance of the floating performance against physiological relevant stress. Therefore, we evaluated the performance of CO2-generating floating bilayer (drug and floating layer) tablets with respect to robustness, drug release profile, pH dependence and floating behaviour. Bilayer tablets were coated with a flexible and water permeable, but CO2-retaining polymer film of either polyvinyl acetate or ammonio-methacrylate copolymer type A. Metformin-HCl was used as a relevant model drug due to its dose-dependent and saturable absorption from the proximal part of the small intestine. To mimic physiological relevant mechanical stress conditions, recently developed dissolution stress tests with pulsed pressures were applied in addition to release studies according to the pharmacopeia. Bilayer tablets coated with polyvinyl acetate showed short floating lag times, reasonable floating strength values, floating durations of more than 24h in simulated gastric fluid and a robust and pH independent release of Metformin-HCl. Tablets coated with ammonio-methacrylate copolymer type A showed a higher permeability for the active ingredient combined with a decreased robustness of the inflated tablets. Both polymers can be used for balloon-like floating devices. The appropriate polymer has to be chosen dependent from the properties of the active ingredient and requested application of the delivery device. Furthermore, the dissolution stress test analysis is able to indicate possible safety issues of gastroretentive formulations as well as to characterise the robustness of formulation principles towards mechanical stresses of bio-relevant intensity. PMID:25086221

Eisenächer, Friederike; Garbacz, Grzegorz; Mäder, Karsten

2014-11-01

135

Color-Encoded Structured Light for Rapid Active Ranging  

Microsoft Academic Search

In this paper, we discuss a novel strategy for rapid acquisition of the range map of a scene employing color-encoded structured light. This technique offers several potential advantages including increased speed and improved accuracy. In this approach we illuminate the scene with a single encoded grid of colored light stripes. The indexing problem, that of matching a detected image plane

Kim L. Boyer; Avinash C. Kak

1987-01-01

136

Gibberellins negatively regulate light-induced nitrate reductase activity in Arabidopsis seedlings.  

PubMed

In the present study, the role of phytohormone gibberellins (GAs) on regulating the nitrate reductase (NR) activity was tested in Arabidopsis seedlings. The NR activity in light-grown Col-0 seedlings was reduced by exogenous GA? (an active form of GAs), but enhanced by exogenous paclobutrazol (PAC, a gibberellin biosynthesis inhibitor), suggesting that GAs negatively regulate the NR activity in light-grown seedlings. Light is known to influence the NR activity through both photosynthesis and phytochromes. When etiolated seedlings were transferred to white or red light, both exogenously applied GA? and PAC were found to function on the NR activity only in the presence of sucrose, implying that GAs are not involved in light signaling-induced but negatively regulate photoproducts-induced NR activity. NR is regulated by light mainly at two levels: transcript level and post-translational level. Our reverse transcription (RT)-PCR assays showed that GAs did not affect the transcript levels of NIA1 and NIA2, two genes that encode NR proteins. But the divalent cations (especially Mg²?) were required for GAs negative regulation of NR activity, in view of the importance of divalent cations during the process of post-translational regulation of NR activity, which indicates that GAs very likely regulate the NR activity at the post-translational level. In the following dark-light shift analyses, GAs were found to accelerate dark-induced decrease, but retard light-induced increase of the NR activity. Furthermore, it was observed that application of G? or PAC could impair diurnal variation of the NR activity. These results collectively indicate that GAs play a negative role during light regulation of NR activity in nature. PMID:21856037

Zhang, Yongqiang; Liu, Zhongjuan; Liu, Rongzhi; Wang, Liguang; Bi, Yurong

2011-12-15

137

Tank Tests of Twin Seaplane Floats  

NASA Technical Reports Server (NTRS)

The following report contains the most essential data for the hydrodynamic portion of the twin-float problem. The following points were successfully investigated: 1) difference between stationary and nonstationary flow; 2) effect of the shape of the step; 3) effect of distance between floats; 4) effect of nose-heavy and tail-heavy moments; 5) effect of the shape of floats; 6) maneuverability.

Herrman, H; Kempf, G; Kloess, H

1928-01-01

138

Photolabile polyethylenimines for light-activated nucleic acid delivery.  

E-print Network

?? Two light-sensitive, cross-linkable polyethylenimines, P25M and B-PC-PEI, were synthesized for the capture and controlled release of nucleic acids. P25M consists of a polyethylenimine (PEI)… (more)

Handwerger, Rachel Gail

2007-01-01

139

Synthesis and polymorphic control for visible light active titania nanoparticles  

NASA Astrophysics Data System (ADS)

Titania (TiO2) is useful for many applications in photocatalysis, antimicrobials, pigment, deodorization, and decomposition of harmful organics and undesirable compounds in the air and waste water under UV irradiation. Among the three phases of TiO2, Rutile, Anatase, and Brookite, studies have been more focused on the anatase and rutile phases. Pure brookite is the most difficult phase to prepare, even under hydrothermal conditions. Predominantly brookite phase TiO2 nanoparticles were prepared by the Water-based Ambient Condition Sol (WACS) process in our laboratory. The objectives of this research were to enhance visible light active (VLA) photocatalytic properties of polymorphic brookite TiO2 by minimizing the lattice defects and narrowing band gap of titania by nitrogen and/or carbon chromophone, and to investigate the deactivation, reusability, and regeneration of the VLA titania in order to design better titania catalysts for organic compound degradation applications. In order to study the influence of hydroxyl content on photocatalytic activities (PCAs) of polymorphic titania nanoparticles, the WACS samples were post-treated by a Solvent-based Ambient Condition Sol (SACS) process in sec-butanol (sec-BuOH). All samples were characterized for phase composition, surface area, hydroxyl contamination, and particle morphology by x-ray diffraction, N2 physisorption, FT-IR, solid state 1H NMR and scanning electron microscopy, and then compared to a commercial titania, Degussa P25. Evaluation of methyl orange (MO) degradation under UV irradiation results showed that the lower lattice hydroxyl content in SACS titania enhanced the PCA. As-prepared titania and SACS samples, which have similar surface areas and crystallinity, were compared in order to prove that the superior PCA came from the reduction in the lattice hydroxyl content. To enhance PCA and VLA properties of WACS, an alternative high boiling point polar solvent, N-methylpyrrolidone (NMP), was utilized in the SACS process at a higher treatment temperature to modify polymorphic titania nanoparticles. This SACS sample was called "SACS-NMP". SACS, using NMP as the solvent, could also extract lattice hydroxyls, and decorate nitrogen on the titania surface. The PCA of SACS-NMP was superior to that of SACS-sec-BuOH. Nitrogen incorporation of SACS-NMP titania was investigated by CHN analysis and x-ray photoelectron spectroscopy (XPS). VL absorbance for all samples was characterized by UV-Vis absorption spectrophotometry. PCA of MO degradation under UV and VL showed that SACS-NMP is a powerful treatment to enhance PCA by minimizing lattice hydroxyls and doping the titania surface with nitrogen. The effect of calcination conditions on SACS-NMP samples was also studied. The calcination conditions, especially the temperature and calcination atmosphere, have an influence on the BET surface area, crystallite size, titania phase content, and PCA under VL irradiation. SACS-NMP samples calcined in air at 200°C for 2 hours showed the best VL activated photocatalytic performance in this research. Additionally, the SACS-NMP sample exhibited superior VL properties to several available reference anatase titania samples. This could be explained as the effective charge separation by the intercrystalline electron transport from brookite to anatase grains complemented by strong VL absorption by the nitrogen species in NMP. The deactivation and regeneration of the VLA titania were investigated and compared to a commercial titania, Kronos VLP7000. PCA of the titania under VL for MO decolorization gradually decreased with increasing testing time and the number of runs. The cause of the deactivation was identified as the deposition of the decomposed MO or the carbonaceous deposit. Among the possible regeneration procedures for used SACS-NMP samples, methanol washing was shown to be the most effective up to ˜80% of the PCA recovery. Accordingly, the SACS-NMP samples could not be completely recovered since a regeneration process would possibly remove some of nitrogen species responsib

Kaewgun, Sujaree

140

Light activation of the sodium pump in blowfly photoreceptors  

Microsoft Academic Search

1.The oxygen consumption of the compound eye in the blowfly was determined during light exposure and in darkness by a manometric measuring technique. Within the first 10 s of exposure to bright white light the oxygen uptake increased up to 20 × the resting value in darkness, which is 2.4 to 3×10-5ml oxygen x min-1 × eye-1.2.The time course of

Kurt Hamdorf; Peter Hochstrate; Gunnar Höglund; Brigitte Burbach; Ursula Wiegand

1988-01-01

141

Ciliary activity by laser light-scattering spectroscopy  

Microsoft Academic Search

The frequency of ciliary beat was measured by laser light-scattering spectroscopy in cultures of ciliated cells of the rabbit\\u000a oviduct. Measurements performed by this new method agree with those obtained by high speed cinematography. When beating cilia\\u000a are illuminated by a laser beam, the scattered light shows a frequency modulation due to the oscillatory motion of cilia.\\u000a The spectral structure

Wylie I. Lee; Pedro Verdugo

1977-01-01

142

Modeling International Space Station (ISS) Floating Potentials  

NASA Technical Reports Server (NTRS)

The floating potential of the International Space Station (ISS) as a function of the electron current collection of its high voltage solar array panels is derived analytically. Based on Floating Potential Probe (FPP) measurements of the ISS potential and ambient plasma characteristics, it is shown that the ISS floating potential is a strong function of the electron temperature of the surrounding plasma. While the ISS floating potential has so far not attained the pre-flight predicted highly negative values, it is shown that for future mission builds, ISS must continue to provide two-fault tolerant arc-hazard protection for astronauts on EVA.

Ferguson, Dale C.; Gardner, Barbara

2002-01-01

143

Floating full-color image with computer-generated alcove rainbow hologram  

NASA Astrophysics Data System (ADS)

We have investigated the floating full color image display with the computer-generated hologram (CGH). The floating image, when utilized as a 3D display, gives strong impression to the viewer. In our previous study, to change the CGH shape from the flat type to the half cylindrical type, the floating image from the output CGH has the nearly 180 degrees viewing angle. However, since the previous CGH does not have wavelength-selectivity, reconstructed image only has a single color. Also, the huge calculation amount of the fringe pattern is big problem. Therefore, we now propose the rainbow-type computer generated alcove hologram. To decrease the calculation amount, the rainbow hologram sacrifices the vertical parallax. Also, this hologram can reconstruct an image with white light. Compared with the previous study of the Fresnel type, the calculation speed becomes 165 times faster. After calculation, we print this hologram with a fringe printer, and evaluate reconstructed floating full color images. In this study, we introduce the computer-generated rainbow hologram into the floating image display. The rainbow hologram can reconstruct full color image with white light illumination. It can be recorded by using a horizontal slit to limit the vertical parallax. Therefore, the slit changes into the half cylindrical slit, the wide viewing angle floating image display can reconstruct full color image.

Yamaguchi, Takeshi; Yoshikawa, Hiroshi

2014-02-01

144

Light Activation of Staphylococcus aureus Toxin YoeBSa1 Reveals Guanosine-Specific Endoribonuclease Activity  

PubMed Central

The Staphylococcus aureus chromosome harbors two homologues of the YefM-YoeB toxin-antitoxin (TA) system. The toxins YoeBSa1 and YoeBSa2 possess ribosome-dependent ribonuclease (RNase) activity in Escherichia coli. This activity is similar to that of the E. coli toxin YoeBEc, an enzyme that, in addition to ribosome-dependent RNase activity, possesses ribosome-independent RNase activity in vitro. To investigate whether YoeBSa1 is also a ribosome-independent RNase, YoeBSa1 was expressed using a novel strategy, and its in vitro RNase activity, sequence specificity, and kinetics were characterized. Y88 of YoeBSa1 was critical for in vitro activity and cell culture toxicity. This residue was mutated to ortho-nitrobenzyl tyrosine (ONBY) via unnatural amino acid mutagenesis. YoeBSa1-Y88ONBY could be expressed in the absence of the antitoxin YefMSa1 in E. coli. Photocaged YoeBSa1-Y88ONBY displayed UV light-dependent RNase activity toward free mRNA in vitro. The in vitro ribosome-independent RNase activity of YoeBSa1-Y88ONBY, YoeBSa1-Y88F, and YoeBSa1-Y88TAG was significantly reduced or abolished. In contrast to YoeBEc, which cleaves RNA at both adenosine and guanosine with a preference for adenosine, YoeBSa1 cleaved mRNA specifically at guanosine. Using this information, a fluorometric assay was developed and used to determine the kinetic parameters for ribosome-independent RNA cleavage by YoeBSa1. PMID:24279911

Larson, Amy S.; Hergenrother, Paul J.

2014-01-01

145

Diet Light  

NSDL National Science Digital Library

In this quick activity, learners observe how the added sugar in a can of soda affects its density and thus, its ability to float in water. Learners explore this phenomenon by testing if two cans of soda (one regular, one diet or "sugar-free") float in a fish-tank filled with water. Use this activity to introduce learners to the concepts of density and water displacement. This resource also explains how atmospheric density plays a role in meteorology and includes thunderstorm safety tips.

Service, National W.

2012-06-26

146

A Variable Light Domain Fluorogen Activating Protein Homodimerizes to Activate Dimethylindole Red†  

PubMed Central

Novel fluorescent tools such as green fluorescent protein analogs and Fluorogen Activating Proteins (FAPs) are useful in biological imaging to track protein dynamics in real-time with low fluorescence background. FAPs are single-chain variable fragments (scFvs) selected from a yeast surface display library that produce fluorescence upon binding a specific dye or fluorogen that is normally not fluorescent when present in solution. FAPs generally consist of human immunoglobulin variable heavy (VH) and variable light (VL) domains covalently attached via a glycine and serine rich linker. Previously, we determined that the yeast surface clone, VH-VL M8, could bind and activate the fluorogen dimethylindole red (DIR), but that the fluorogen activation properties were localized to the M8VL domain. We report here that both NMR and X-ray diffraction methods indicate the M8VL forms non-covalent, anti-parallel homodimers that are the fluorogen activating species. The M8VL homodimers activate DIR by restriction of internal rotation of the bound dye. These structural results, together with directed evolution experiments of both VH-VL M8 and M8VL, led us to rationally design tandem, covalent homodimers of M8VL domains joined by a flexible linker that have a high affinity for DIR and good quantum yield. PMID:22390683

Senutovitch, Nina; Stanfield, Robyn L.; Bhattacharyya, Shantanu; Rule, Gordon S.; Wilson, Ian A.; Armitage, Bruce A.; Waggoner, Alan S.; Berget, Peter B.

2012-01-01

147

A Variable Light Domain Fluorogen Activating Protein Homodimerizes To Activate Dimethylindole Red  

SciTech Connect

Novel fluorescent tools such as green fluorescent protein analogues and fluorogen activating proteins (FAPs) are useful in biological imaging for tracking protein dynamics in real time with a low fluorescence background. FAPs are single-chain variable fragments (scFvs) selected from a yeast surface display library that produce fluorescence upon binding a specific dye or fluorogen that is normally not fluorescent when present in solution. FAPs generally consist of human immunoglobulin variable heavy (V{sub H}) and variable light (V{sub L}) domains covalently attached via a glycine- and serine-rich linker. Previously, we determined that the yeast surface clone, V{sub H}-V{sub L} M8, could bind and activate the fluorogen dimethylindole red (DIR) but that the fluorogen activation properties were localized to the M8V{sub L} domain. We report here that both nuclear magnetic resonance and X-ray diffraction methods indicate the M8V{sub L} forms noncovalent, antiparallel homodimers that are the fluorogen activating species. The M8V{sub L} homodimers activate DIR by restriction of internal rotation of the bound dye. These structural results, together with directed evolution experiments with both V{sub H}-V{sub L} M8 and M8V{sub L}, led us to rationally design tandem, covalent homodimers of M8V{sub L} domains joined by a flexible linker that have a high affinity for DIR and good quantum yields.

Senutovitch, Nina; Stanfield, Robyn L.; Bhattacharyya, Shantanu; Rule, Gordon S.; Wilson, Ian A.; Armitage, Bruce A.; Waggoner, Alan S.; Berget, Peter B. (Scripps); (CM)

2012-07-11

148

Blue light irradiation affects anthocyanin content and enzyme activities involved in postharvest strawberry fruit.  

PubMed

Blue light irradiation was applied to postharvest strawberry fruit to explore its influence on anthocyanin content and anthocyanin biosynthetic enzyme activities. Strawberry fruit was irradiated with blue light at 40 ?mol m(-2) s(-1) for 12 days at 5 °C. The results indicated that blue light treatment improved total anthocyanin content in strawberry fruit during storage. Meanwhile, the treatment increased the activities of glucose-6-phosphate, shikimate dehydrogenase, tyrosine ammonia-lyase, phenylalanine ammonia-lyase, cinnamate-4-hydroxylase, 4-coumarate/coenzyme A ligase, dihydroflavonol-4-reductase, chalcone synthase, flavanone-3-?-hydroxylase, anthocyanin synthase, and UDP-glycose flavonoid-3-O-glycosyltranferase, which suggested that the enhancement of anthocyanin concentration by blue light might result from the activation of its related enzymes. Blue light might be proposed as a supplemental light source in the storage of strawberry fruit to improve its anthocyanin content. PMID:24783962

Xu, Feng; Cao, Shifeng; Shi, Liyu; Chen, Wei; Su, Xinguo; Yang, Zhenfeng

2014-05-21

149

Light Travel Time and the Size of Active Galaxies  

NSDL National Science Digital Library

Using real data from NASA's Fermi satellite, students determine the size and energy of an active galaxy flare region. This activity includes background information for teachers, student worksheets, procedures, adaptations, extensions, an assessment rubric, and related resources. This is activity 3 of 3 in the "Active Galaxies Educator's Guide."

150

An electrically excited nanoscale light source with active angular control of the emitted light.  

PubMed

We report on the angular distribution, polarization, and spectrum of the light emitted from an electrically controlled nanoscale light source. This nanosource of light arises from the local, low-energy, electrical excitation of localized surface plasmons (LSP) on individual gold nanoparticles using a scanning tunneling microscope (STM). The gold nanoparticles (NP) are chemically synthesized truncated bitetrahedrons. The emitted light is collected through the transparent substrate and the emission characteristics (angular distribution, polarization, and spectrum) are analyzed. These three observables are found to strongly depend on the lateral position of the STM tip with respect to the triangular upper face of the gold NP. In particular, the resulting light emission changes orientation when the electrical excitation via the STM tip is moved from the base to the vertex of the triangular face. On the basis of the comparison of the experimental observations with an analytical dipole model and finite-difference time-domain (FDTD) calculations, we show that this behavior is linked to the selective excitation of the out-of-plane and in-plane dipolar LSP modes of the NP. This selective excitation is achieved through the lateral position of the tip with respect to the symmetry center of the NP. PMID:23927672

Le Moal, Eric; Marguet, Sylvie; Rogez, Benoît; Mukherjee, Samik; Dos Santos, Philippe; Boer-Duchemin, Elizabeth; Comtet, Geneviève; Dujardin, Gérald

2013-09-11

151

Wave drag on floating bodies  

PubMed Central

We measure the deceleration of liquid nitrogen drops floating at the surface of a liquid bath. On water, the friction force is found to be about 10 to 100 times larger than on a solid substrate, which is shown to arise from wave resistance. We investigate the influence of the bath viscosity and show that the dissipation decreases as the viscosity is increased, owing to wave damping. The measured resistance is well predicted by a model imposing a vertical force (i.e., the drop weight) on a finite area, as long as the wake can be considered stationary. PMID:21876186

Le Merrer, Marie; Clanet, Christophe; Quéré, David; Raphaël, Élie; Chevy, Frédéric

2011-01-01

152

LIGHT, a member of the TNF superfamily, activates Stat3 mediated by NIK pathway  

SciTech Connect

Stat3, a member of the signal transducers and activators of transcription (STAT) family, is a key signal transduction protein activated by numerous cytokines, growth factors, and oncoproteins that controls cell proliferation, differentiation, development, survival, and inflammation. Constitutive activation of Stat3 has been found frequently in a wide variety of human tumors and induces cellular transformation and tumor formation. In this study, we demonstrated that LIGHT, a member of tumor necrosis factor superfamily, activates Stat3 in cancer cells. LIGHT induces dose-dependent activation of Stat3 by phosphorylation at both the tyrosine 705 and serine 727 residues. The activation of Stat3 by LIGHT appears to be mediated by NIK phosphorylation. Expression of a kinase-inactive NIK mutant abolished LIGHT induced Stat3 activation. Overexpression of an active NIK induces Stat3 activation by phosphorylation at the both tyrosine 705 and serine 727 residues. Activation of Stat3 by NIK requires NIK kinase activity as showed by kinase assays. In addition, LIGHT increases the expression of Stat3 target genes including cyclin D1, survivin, and Bcl-xL, and stimulates human LNCaP prostate cancer cell growth in vitro which can be blocked by expression of a dominant-negative Stat3 mutant. Taken together, these results indicate that in addition to activating NF-{kappa}B/p52, LIGHT also activates Stat3. Activation of Stat3 together with activating non-canonical NF-{kappa}B/p52 signaling by LIGHT may maximize its effects on cellular proliferation, survival, and inflammation.

Nadiminty, Nagalakshmi [Departments of Medicine, Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, NY 14263 (United States); Chun, Jae Yeon [Departments of Medicine, Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, NY 14263 (United States); Hu, Yan [Departments of Medicine, Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, NY 14263 (United States); Dutt, Smitha [Departments of Medicine, Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, NY 14263 (United States); Lin, Xin [Department of Molecular Oncology, MD Anderson Cancer Center, Houston, TX 77030 (United States); Gao, Allen C. [Departments of Medicine, Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, NY 14263 (United States)]. E-mail: allen.gao@roswellpark.org

2007-07-27

153

Stem cell activation by light guides plant organogenesis  

PubMed Central

Leaves originate from stem cells located at the shoot apical meristem. The meristem is shielded from the environment by older leaves, and leaf initiation is considered to be an autonomous process that does not depend on environmental cues. Here we show that light acts as a morphogenic signal that controls leaf initiation and stabilizes leaf positioning. Leaf initiation in tomato shoot apices ceases in the dark but resumes in the light, an effect that is mediated through the plant hormone cytokinin. Dark treatment also affects the subcellular localization of the auxin transporter PIN1 and the concomitant formation of auxin maxima. We propose that cytokinin is required for meristem propagation, and that auxin redirects cytokinin-inducible meristem growth toward organ formation. In contrast to common wisdom over the last 150 years, the light environment controls the initiation of lateral organs by regulating two key hormones: auxin and cytokinin. PMID:21724835

Yoshida, Saiko; Mandel, Therese; Kuhlemeier, Cris

2011-01-01

154

Stem cell activation by light guides plant organogenesis.  

PubMed

Leaves originate from stem cells located at the shoot apical meristem. The meristem is shielded from the environment by older leaves, and leaf initiation is considered to be an autonomous process that does not depend on environmental cues. Here we show that light acts as a morphogenic signal that controls leaf initiation and stabilizes leaf positioning. Leaf initiation in tomato shoot apices ceases in the dark but resumes in the light, an effect that is mediated through the plant hormone cytokinin. Dark treatment also affects the subcellular localization of the auxin transporter PIN1 and the concomitant formation of auxin maxima. We propose that cytokinin is required for meristem propagation, and that auxin redirects cytokinin-inducible meristem growth toward organ formation. In contrast to common wisdom over the last 150 years, the light environment controls the initiation of lateral organs by regulating two key hormones: auxin and cytokinin. PMID:21724835

Yoshida, Saiko; Mandel, Therese; Kuhlemeier, Cris

2011-07-01

155

Ambipolar organic thin-film transistor-based nano-floating-gate nonvolatile memory  

SciTech Connect

An ambipolar organic thin-film transistor-based nano-floating-gate nonvolatile memory was demonstrated, with discrete distributed gold nanoparticles, tetratetracontane (TTC), pentacene as the floating-gate layer, tunneling layer, and active layer, respectively. The electron traps at the TTC/pentacene interface were significantly suppressed, which resulted in an ambipolar operation in present memory. As both electrons and holes were supplied in the channel and trapped in the floating-gate by programming/erasing operations, respectively, i.e., one type of charge carriers was used to overwrite the other, trapped, one, a large memory window, extending on both sides of the initial threshold voltage, was realized.

Han, Jinhua; Wang, Wei, E-mail: wwei99@jlu.edu.cn; Ying, Jun; Xie, Wenfa [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China)] [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China)

2014-01-06

156

14 CFR 29.757 - Hull and auxiliary float strength.  

Code of Federal Regulations, 2010 CFR

...float strength. The hull, and auxiliary floats if used, must withstand the water loads prescribed by § 29.519 with a rational and conservative distribution of local and distributed water pressures over the hull and float bottom. [Amdt....

2010-01-01

157

14 CFR 29.757 - Hull and auxiliary float strength.  

Code of Federal Regulations, 2012 CFR

...float strength. The hull, and auxiliary floats if used, must withstand the water loads prescribed by § 29.519 with a rational and conservative distribution of local and distributed water pressures over the hull and float bottom. [Amdt....

2012-01-01

158

14 CFR 29.757 - Hull and auxiliary float strength.  

Code of Federal Regulations, 2011 CFR

...float strength. The hull, and auxiliary floats if used, must withstand the water loads prescribed by § 29.519 with a rational and conservative distribution of local and distributed water pressures over the hull and float bottom. [Amdt....

2011-01-01

159

Regulation of transcription through light-activation and light-deactivation of triplex-forming oligonucleotides in mammalian cells.  

PubMed

Triplex-forming oligonucleotides (TFOs) are efficient tools to regulate gene expression through the inhibition of transcription. Here, nucleobase-caging technology was applied to the temporal regulation of transcription through light-activated TFOs. Through site-specific incorporation of caged thymidine nucleotides, the TFO:DNA triplex formation is blocked, rendering the TFO inactive. However, after a brief UV irradiation, the caging groups are removed, activating the TFO and leading to the inhibition of transcription. Furthermore, the synthesis and site-specific incorporation of caged deoxycytidine nucleotides within TFO inhibitor sequences was developed, allowing for the light-deactivation of TFO function and thus photochemical activation of gene expression. After UV-induced removal of the caging groups, the TFO forms a DNA dumbbell structure, rendering it inactive, releasing it from the DNA, and activating transcription. These are the first examples of light-regulated TFOs and their application in the photochemical activation and deactivation of gene expression. In addition, hairpin loop structures were found to significantly increase the efficacy of phosphodiester DNA-based TFOs in tissue culture. PMID:22540192

Govan, Jeane M; Uprety, Rajendra; Hemphill, James; Lively, Mark O; Deiters, Alexander

2012-07-20

160

Biological activity of photoproducts of merocyanine 540 generated by laser-light activation  

NASA Astrophysics Data System (ADS)

Controlled exposure of photoactive compounds to light prior to their use in biological targets results in the formation of heretofore unknown photoproducts. This process of photoproduct generation, termed "preactivation," renders the photactive compound capable of systemic use without further dependence on light. Preactivation of mercyanin 540 (MC540) and several other photoactive compounds is achievable by exposure to CW and pulse laser radiation. The singlet oxygen generated at excited states attacks the dye molucule itself, resulting in the formation of biologically active photoproducts. For preactivated MC540 (photoproducts of MC540) generated by exposure to argon laser light (514 nm) and light from free-electron laser, we have demonstrated its effectiveness in selective killing of certain types of cultured tumor cells as well as human immunodeficiency virus type 1 (HIV-1) with very low, if any, damage to normal cells and tisues. For example, approximately 90% of the Burkitt's lymphoma Daudi cells and HL-60 leukemic cells are killed by preactivated MC540 at a concentration of 120 ?g/ml. A two-hour treatment of cultured cells with buthionine sulfoxamine followed by the treatement with preactivated MC540 reults in 99.99% inhibition of clonogenic tumor stem cell growth. We also have demonstrated that preactivated MC540 is very effective in killing cell-free and cell-associated HIV-1. It also is very effective in killing HIV-1 and simian immunodeficiency virus (SIV) in virus-infected blood in vitro as determined by reverse transcriptase, P24, P17, core antigen expression and synctium formation. Treatment of HIV-1 with preactivated MC540 renders the treated HIV-1 incapable of binding to CD4 target molecules on T cells as determined by immunofluorescence and radioimmunoprecipitation assays. In vivo toxicology studies show that preactivated MC540 is very well tolerated and does not produce any signs of adverse reaction at the therapeutic doses, as determined by physical examination, serum eletrolyte measurements, blood chemistry, and histopathology. Photoproducts generated via the process of preactivation are currently under investigation for optimum activity and yield using high-peak, power-pulse lasers.

Gulliya, Kirpal S.; Chanh, Tran C.; Pervaiz, Shazib; Harriman, Anthony; Matthews, James Lester

1992-08-01

161

Human and Drosophila cryptochromes are light activated by flavin photoreduction in living cells.  

PubMed

Cryptochromes are a class of flavoprotein blue-light signaling receptors found in plants, animals, and humans that control plant development and the entrainment of circadian rhythms. In plant cryptochromes, light activation is proposed to result from photoreduction of a protein-bound flavin chromophore through intramolecular electron transfer. However, although similar in structure to plant cryptochromes, the light-response mechanism of animal cryptochromes remains entirely unknown. To complicate matters further, there is currently a debate on whether mammalian cryptochromes respond to light at all or are instead activated by non-light-dependent mechanisms. To resolve these questions, we have expressed both human and Drosophila cryptochrome proteins to high levels in living Sf21 insect cells using a baculovirus-derived expression system. Intact cells are irradiated with blue light, and the resulting cryptochrome photoconversion is monitored by fluorescence and electron paramagnetic resonance spectroscopic techniques. We demonstrate that light induces a change in the redox state of flavin bound to the receptor in both human and Drosophila cryptochromes. Photoreduction from oxidized flavin and subsequent accumulation of a semiquinone intermediate signaling state occurs by a conserved mechanism that has been previously identified for plant cryptochromes. These results provide the first evidence of how animal-type cryptochromes are activated by light in living cells. Furthermore, human cryptochrome is also shown to undergo this light response. Therefore, human cryptochromes in exposed peripheral and/or visual tissues may have novel light-sensing roles that remain to be elucidated. PMID:18597555

Hoang, Nathalie; Schleicher, Erik; Kacprzak, Sylwia; Bouly, Jean-Pierre; Picot, Marie; Wu, William; Berndt, Albrecht; Wolf, Eva; Bittl, Robert; Ahmad, Margaret

2008-07-01

162

Active dielectric antenna on chip for spatial light modulation  

E-print Network

in an evanescently-coupled waveguide, resulting in various on-chip photonic devices including electro-optic modulators1,2 , filters3­5 , buffers6,7 and biosensors8­10 . Their compact sizes, low power consumptions demonstrate a silicon-based spatial light modulator (SLM) which is the key element in many free-space optical

Mellor-Crummey, John

163

El Hierro's floating stones as messengers of crust-magma interaction at depth  

NASA Astrophysics Data System (ADS)

During the early stages of the submarine eruption that started on October 10 2011 south of El Hierro, Canary Islands, Spain, peculiar eruption products were found floating on the sea surface. These centimetre- to decimetre-sized "bombs" have been termed "restingolites" after the nearby village La Restinga and consist of a basaltic rind and a white to light grey core that resembles pumice in texture. According to Troll et al. (2011; see also Troll et al. EGU 2012 Abstracts), this material consists of a glassy matrix hosting extensive vesicle networks, which results in extremely low densities allowing these rocks to float on sea water. Mineralogical and geochemical analyses reveal that the "restingolites" originate from the sedimentary rocks (sand-, silt-, and mudstones) that form layer 1 of the oceanic crust beneath El Hierro. During the onset and early stages of the eruption, magma ponded at the base of this sedimentary sequence, breaking its way through the sedimentary rocks to the ocean floor. The textures of the "restingolites" reveal that crust-magma interaction during fragmentation and transport of the xenoliths involved rapid partial melting and volatile exsolution. Xenoliths strikingly similar to those from El Hierro are known from eruptions on other Canary Islands (e.g. La Palma, Gran Canaria, and Lanzarote). In fact, they resemble in texture xenoliths of various protoliths from volcanic areas worldwide (e.g. Krakatao, Indonesia, Cerro Quemado, Guatemala, Laacher See, Germany). This indicates that the process of partial melting and volatile exsolution, which the "restingolites" bear witness of, is probably occurring frequently during shallow crustal magma emplacement. Thermomechanical numerical models of the effect of the density decrease associated with the formation of vesicle networks in partially molten xenoliths show that xenoliths of crustal rocks initially sink in a magma chamber, but may start to float to the chamber roof once they start to heat up and vesiculate. The "floating stones" from El Hierro thus represent the products of crust-magma interaction beneath the Canary Islands, but is probably relevant in most volcanic areas and tectonic settings. In addition, xenolith devolatilisation has important general implications for the mechanics of crustal recycling, magma emplacement into the upper crust and volatile release from active volcanic systems.

Burchardt, S.; Troll, V. R.; Schmeling, H.; Koyi, H.; Blythe, L. S.; Longpré, M. A.; Deegan, F. M.

2012-04-01

164

IEEE Standard unifies arithmetic model Floating points  

E-print Network

years use IEEE floating-point arithmetic. This doesn't mean that they all get exactly the same resultsIEEE Standard unifies arithmetic model Floating points by Cleve Moler C l e v e ' s C o r n e r I f you look carefully at the definition of fundamental arithmetic operations like addition

Beron-Vera, Francisco Javier

165

Multiplications of floating point expansions Marc Daumas  

E-print Network

of overflow or underflow, the process is error free and possibly more efficient than its integer based counterMultiplications of floating point expansions Marc Daumas CNRS - Lab LIP - UMR 8512 - ENS de Lyon computers, the floating point unit is the part of the processor delivering the highest computing power

California at Davis, University of

166

Future float zone development in industry  

NASA Technical Reports Server (NTRS)

The present industrial requirements for float zone silicon are summarized. Developments desired by the industry in the future are reported. The five most significant problems faced today by the float zone crystal growth method in industry are discussed. They are economic, large diameter, resistivity uniformity, control of carbon, and swirl defects.

Sandfort, R. M.

1980-01-01

167

Floating Entanglement Witness Measure and Genetic Algorithm  

E-print Network

In this paper based on the notion of entanglement witness, a new measure of entanglement called floating entanglement witness measure is introduced which satisfies some of the usual properties of a good entanglement measure. By exploiting genetic algorithm, we introduce a classical algorithm that computes floating entanglement witness measure. This algorithm also provides a method for finding entanglement witness for a given entangled state.

A. Baghbanpourasl; G. Najarbashi; M. Seyedkazemi

2007-08-27

168

Interval Arithmetic Implementations using Floating Point Arithmetic  

Microsoft Academic Search

This paper presents some algorithms implementing interval arithmetic using floating point arithmetic. The algorithms apply to almost any digital computer supporting normalized floating point arithmetic and provide better performance than conventional interval arithmetic program libraries. For reasons of generality and machine independence, algorithms are presented in a high-level language. They are intended to be used as an implementation guide for

Michael Clemmesen

1984-01-01

169

Interval arithmetic implementations: using floating point arithmetic  

Microsoft Academic Search

This paper presents some algorithms implementing interval arithmetic using floating point arithmetic. The algorithms apply to almost any digital computer supporting normalized floating point arithmetic and provide better performance than conventional interval arithmetic program libraries. For reasons of generality and machine independence, algorithms are presented in a high-level language. They are intended to be used as an implementation guide for

Michael Clemmesen

1984-01-01

170

Human and Drosophila Cryptochromes Are Light Activated by Flavin Photoreduction in Living Cells  

Microsoft Academic Search

Cryptochromes are a class of flavoprotein blue-light signaling receptors found in plants, animals, and humans that control plant development and the entrainment of circadian rhythms. In plant cryptochromes, light activation is proposed to result from photoreduction of a protein-bound flavin chromophore through intramolecular electron transfer. However, although similar in structure to plant cryptochromes, the light-response mechanism of animal cryptochromes remains

Nathalie Hoang; Erik Schleicher; Sylwia Kacprzak; Jean-Pierre Bouly; Marie Picot; William Wu; Albrecht Berndt; Eva Wolf; Robert Bittl; Margaret Ahmad

2008-01-01

171

Sinking and Floating: A Graphical Representation of the Concept of Density  

NSDL National Science Digital Library

Density is a derived quantity that can be confusing for middle school students. Try using a graphical depiction of mass and volume to guide students in understanding and applying this concept. In this activity, students will collect various materials, test whether each of the objects will float or sink in tap water, and measure the volume and mass of each object. By graphing the data, students will make the important conceptual leap from their initial thoughts and findings to exact criteria for floating.

Benedis-Grab, Gregory

2006-10-01

172

Nitrate reductase activity in corn seedlings as affected by light and nitrate content of nutrient media  

Microsoft Academic Search

Young corn plants placed in complete darkness for 48 hours lost 90% of their nitrate reductase activity. The activity was quickly restored when the plants were returned to the light. In other experiments, corn plants were grown under artificial shade in the greenhouse. The nitrate reductase activity in these plants decreased roughly in proportion to the amount of shading. It

R. H. Hageman; D. Flesher

1960-01-01

173

Light-activated ruthenium complexes photobind DNA and are cytotoxic in the photodynamic therapy window.  

PubMed

Incorporation of biquinoline ligands into Ru(II) polypyridyl complexes produces light-activated systems that eject a ligand and photobind DNA after irradiation with visible and near-IR light. Structural analysis shows that distortion facilitates the photochemistry, and gel shift and cytotoxicity studies prove the compounds act as anti-cancer photodynamic therapy (PDT) agents in the tissue penetrant region. PMID:22908094

Wachter, Erin; Heidary, David K; Howerton, Brock S; Parkin, Sean; Glazer, Edith C

2012-10-01

174

Short-term effects of high light intensities on soybean nodule activity and photosynthesis  

Microsoft Academic Search

There is little information available on the effects of high light intensity (HLI) on nitrogenase activity in legume nodules. Inhibitory as well as stimulatory effects have been described. The hypothesis that an increase in carbohydrate production is involved in these effects was tested by comparing the effects of high light, high CO2, or low O2 exposure of the shoot. The

Rajae Vidal; Alain Gerbaud; Didier Vidal

1996-01-01

175

Determining the Typical Nanoflare Cadence in Active Regions: Modeling Light Curves of Active Regions  

NASA Astrophysics Data System (ADS)

Active region coronal loops visible at 1MK are likely composed of many unresolved strands, heated by storms of impulsive nanoflares. Though well-studied, these loops often contribute only a fraction of the total emission in an active region; the degree to which the entire active region is heated in the same manner as loops are is highly debated. Is the majority of coronal active region plasma heated impulsively, or is the majority of the heating quasi-steady? Addressing this question is complicated by the fact that the corona is optically thin: many thousands of strands which are heated completely independently are contributing to the total emission along a given line of sight. Furthermore, certain geometries preclude even the best background subtraction methods from fully isolating the emission from even a single coronal loop. Therefore, a different and necessary approach to analyzing active region heating is to account for emission along the line of sight from all of the contributing strands. We model the active region corona as a line-of-sight integration of many thousands of completely independently heated strands. The emission from these flux tubes may be time dependent, quasi-steady, or a mix of both, depending on the cadence of heat release on each strand. We examine a full range of heat cadences from effectively steady (heat pulse repeat time << plasma cooling time) to fully impulsive (heat pulse repeat time >> plasma cooling time) and model the resulting emission when superposing strands undergoing these differing heat cycles. We demonstrate that despite the superposition of randomly heated strands, different distributions of heat cadences produce distinct signatures in light curves observed with multi-wavelength and high time cadence data, such as those from the AIA telescopes on SDO. For this reason, high time cadence spectral information for lines sensitive to the 1-10 MK range will be especially useful in future missions. Using these model predictions, we evaluate the typical cadence of heat release in different active regions and patterns therein, which is a crucial constraint on coronal heating mechanisms.

Viall, N. M.; Klimchuk, J. A.

2011-12-01

176

Multiprocessing system for performing floating point arithmetic operations  

SciTech Connect

This patent describes a data processing system. It comprises: a fixed point arithmetic processor means for performing fixed point arithmetic operations and including control means for decoding a floating point arithmetic instruction specifying a floating point arithmetic operation, and an addressing means for computing addresses for floating point data for the floating point operation from a memory means. The memory means for storing data and including means for receiving the addresses from the fixed point arithmetic processor means and providing the floating point data to a floating point arithmetic processor means; and the floating point arithmetic processor means for performing floating point arithmetic operations and including control means for decoding the floating point instruction and performing the specified floating point arithmetic operation upon the floating point data from the memory means.

Nguyenphu, M.; Thatcher, L.E.

1990-10-02

177

GAS PHASE SELECTIVE PHOTOXIDATION OF ALCOHOLS USING LIGHT-ACTIVATED TITANIUM DIOXIDE AND MOLECULAR OXYGEN  

EPA Science Inventory

Gas Phase Selective Oxidation of Alcohols Using Light-Activated Titanium Dioxide and Molecular Oxygen Gas phase selective oxidations of various primary and secondary alcohols are studied in an indigenously built stainless steel up-flow photochemical reactor using ultravi...

178

Active control of light based on polarization-coupling cascading  

NASA Astrophysics Data System (ADS)

In this letter, we proposed a novel method for optical manipulation based on polarization-coupling cascading in MgO-doped periodically poled lithium niobate crystal. Polarization-coupling cascading, a series of energy exchanges between two orthogonally polarized beams close to phase matching condition, can also lead to phase shifts, in analogy with that in cascaded second-order nonlinearities. In addition, the parameters of light such as phase, amplitude, and group velocity can be modulated by changing the relative power ratio of the incident continuous wave beams. The phase control was demonstrated by Newton's rings experiment, which was in good agreement with the theoretical prediction.

Huo, Juan; Zheng, Yuanlin; Chen, Xianfeng

2014-10-01

179

Remote control of molecular motors using light-activated gearshifting  

NASA Astrophysics Data System (ADS)

Engineering molecular motors with dynamically controllable properties will allow selective perturbation of mechanical processes in vivo and provide sophisticated components for directed nanoscale transport in vitro. We previously constructed myosin motors that respond to a change in [Ca++] by reversing their direction of motion along the polarized actin filament [1]. To expand the potential applications of controllable molecular motors, we have now developed myosins that shift gears in response to blue light illumination. Light is a versatile control signal that can be readily modulated in time and space, and is generally orthogonal to cellular signaling. Using structure-guided protein engineering, we have incorporated LOV photoreceptor domains into the lever arms of chimeric myosins, resulting in motors that robustly speed up, slow down, or switch directions upon illumination. These genetically encoded motors should be directly deployable inside living cells. Our successful designs include constructs based on two different myosin classes, and we show that optical velocity control can be implemented in motors that move at microns/sec speeds, enabling practical biological and bioengineering applications.[4pt] [1] Chen, L., Nakamura, M., Schindler,T.D., and Bryant Z. (2012). Nat. Nanotechnol. 7, 252-6.

Bryant, Zev

2013-03-01

180

WindWaveFloat Final Report  

SciTech Connect

Principle Power Inc. and National Renewable Energy Lab (NREL) have completed a contract to assess the technical and economic feasibility of integrating wave energy converters into the WindFloat, resulting in a new concept called the WindWaveFloat (WWF). The concentration of several devices on one platform could offer a potential for both economic and operational advantages. Wind and wave energy converters can share the electrical cable and power transfer equipment to transport the electricity to shore. Access to multiple generation devices could be simplified, resulting in cost saving at the operational level. Overall capital costs may also be reduced, provided that the design of the foundation can be adapted to multiple devices with minimum modifications. Finally, the WindWaveFloat confers the ability to increase energy production from individual floating support structures, potentially leading to a reduction in levelized energy costs, an increase in the overall capacity factor, and greater stability of the electrical power delivered to the grid. The research conducted under this grant investigated the integration of several wave energy device types into the WindFloat platform. Several of the resulting system designs demonstrated technical feasibility, but the size and design constraints of the wave energy converters (technical and economic) make the WindWaveFloat concept economically unfeasible at this time. Not enough additional generation could be produced to make the additional expense associated with wave energy conversion integration into the WindFloat worthwhile.

Alla Weinstein, Dominique Roddier, Kevin Banister

2012-03-30

181

Light pulses entrain the circadian activity rhythm of a diurnal rodent (Ammospermophilus leucurus).  

PubMed

Circadian rhythms of wheel-running activity of the antelope ground squirrel (Ammospermophilus leucurus) were entrained by light-dark cycles (LD: 100 1x vs total darkness) with periods (T) between ca 23.75 and 24.75 hr. Two 1-hr light pulses per cycle ('skeleton photoperiods') with T = 24.25 hr as well as one 1-hr light pulse per cycle with Ts of 23.75 and 24.25 hr were effective in entraining the circadian activity rhythms in at least 50% of the antelope ground squirrels. Phase and period responses to single 1-hr light pulses were measured which depend on the initial phase and period of the rhythm. It is concluded that discrete (phasic) light input contributes to the mechanism of entrainment to LD cycles in diurnal rodents. PMID:6661897

Pohl, H

1983-01-01

182

Comparisons of three practical field devices used to measure personal light exposures and activity levels  

PubMed Central

This paper documents the spectral and spatial performance characteristics of two new versions of the Daysimeter, devices developed and calibrated by the Lighting Research Center to measure and record personal circadian light exposure and activity levels, and compares them to those of the Actiwatch Spectrum (Philips Healthcare). Photometric errors from the Daysimeters and the Actiwatch Spectrum were also determined for various types of light sources. The Daysimeters had better photometric performance than the Actiwatch Spectrum. To assess differences associated with measuring light and activity levels at different locations on the body, older adults wore four Daysimeters and an Actiwatch Spectrum for five consecutive days. Wearing the Daysimeter or Actiwatch Spectrum on the wrist compromises accurate light measurements relative to locating a calibrated photosensor at the plane of the cornea. PMID:24443644

Figueiro, M G; Hamner, R; Bierman, A; Rea, M S

2012-01-01

183

Light promotes an increase of cytokinin oxidase/dehydrogenase activity during senescence of barley leaf segments.  

PubMed

Following a study of the relationship between cytokinin oxidase/dehydrogenase (CKX) and senescence in darkened barley leaf segments, we have now investigated the influence of light on the in vitro activity of CKX. Seedlings of Hordeum vulgare L. were grown for 8d under a light/dark regime of 18h white light and 6h darkness. Then apical parts of 7cm length were cut from the first foliage leaves and their bases were placed in water. In segments kept in the dark, the CKX activity measured by cleavage of N(6)-(?(2)-isopentenyl)adenine rose from 0.1pkat (gFW)(-1) to 0.8pkat (g initial FW)(-1) within the first 4d of incubation. In contrast, in segments kept under the light/dark regime it reached a value of 8.6pkat (g initial FW)(-1) over the same time period. The chlorophyll a content declined slightly slower during light/dark cycling than in darkness. In contrast to segments and isolated laminae, corresponding attached laminae exhibited less CKX activity after 2d under light/dark conditions than after 2d in the dark. The activity in attached laminae of first foliage leaves of plants growing in light/dark cycling increased strongly only when the plants were older than 4 weeks. In line with this, the CKX activity in attached laminae of flag leaves of barley growing in fields increased in a late developmental state. The senescence of darkened isolated laminae of Zea mays L. and Phragmites australis (Cav.) Trin. ex Steudel was associated with an enhancement of CKX activity too. Because in most cases a positive correlation between CKX activity and senescence was found, it is likely that the enzyme promotes senescence by destroying cytokinins, which help to keep Poaceae leaves green. Light may promote not only cytokinin degradation but also the formation of bioactive cytokinins in leaf segments. PMID:21106275

Schlüter, Torsten; Leide, Jana; Conrad, Klaus

2011-05-01

184

Extended Onshore Control of a Floating Wind Turbine with Wave Disturbance Reduction  

NASA Astrophysics Data System (ADS)

Reaching for higher wind resources beyond the water depth limitations of monopile wind turbines, there has arisen the alternative of using floating wind turbines. But the response of wave induced loads significantly increases for floating wind turbines. Applying conventional onshore control strategies to floating wind turbines has been shown to impose negative damped oscillations in fore-aft due to the low natural frequency of the floating structure. Thus, we suggest a control loop extension of the onshore controller which stabilizes the system and reduces the wave disturbance. The results shows that when adding the suggested control loop with disturbance reduction to the system, improved performance is observed in power fluctuations, blade pitch activity, and platform oscillations.

Christiansen, S.; Knudsen, T.; Bak, T.

2014-12-01

185

Biphasic myosin II light chain activation during clot retraction.  

PubMed

Clot retraction is an essential step during primary haemostasis, thereby promoting thrombus stability and wound healing. Integrin ?IIb?3 plays a critical role in clot retraction, by inducing acto-myosin interactions that allow platelet cytoskeleton reorganisation. However, the signalling pathways that lead to clot retraction are still misunderstood. In this study, we report the first data on the kinetics of myosin II light chain (MLC) phosphorylation during clot retraction. We found an early phosphorylation peak followed by a second peak. By using specific inhibitors of kinases and small G proteins, we showed that MLC kinase (MLCK), RhoA/ROCK, and Rac-1 were involved in clot retraction and in the early MLC phosphorylation peak. Only Rac-1 and actin polymerisation, controlled by outside-in signalling, were crucial to the second MLC phosphorylation peak. PMID:23965920

Egot, Marion; Kauskot, Alexandre; Lasne, Dominique; Gaussem, Pascale; Bachelot-Loza, Christilla

2013-12-01

186

Floating point arithmetic in future supercomputers  

NASA Technical Reports Server (NTRS)

Considerations in the floating-point design of a supercomputer are discussed. Particular attention is given to word size, hardware support for extended precision, format, and accuracy characteristics. These issues are discussed from the perspective of the Numerical Aerodynamic Simulation Systems Division at NASA Ames. The features believed to be most important for a future supercomputer floating-point design include: (1) a 64-bit IEEE floating-point format with 11 exponent bits, 52 mantissa bits, and one sign bit and (2) hardware support for reasonably fast double-precision arithmetic.

Bailey, David H.; Barton, John T.; Simon, Horst D.; Fouts, Martin J.

1989-01-01

187

Construction of Control System for Floating High Energy Capacitors  

NASA Astrophysics Data System (ADS)

The circuitry for the Caltech magnetic reconnection experiment under construction requires two independent floating high energy capacitor power supplies to create linked plasma loops. This project requires the building of systems for controlling plasma generation, including timing circuitry to control the sequences of operation. Unlike with previous designs, timing functions are completely contained on a single printed circuit board. This allows the design to be easily replicated for use with the multiple independent capacitor involved. The timing circuitry first activates a high voltage power supply, then connects the power supply to the capacitor, and then disconnects the power supply so that the charged capacitor is floating. The circuitry then sends out a ``ready'' signal to a sequencer, which sequentially triggers the gas puff valves, bias magnetic field supply, and ignitron switch for the capacitor. The control circuit sequencing has been tested successfully with the capacitor discharging into a dummy load.

Tobin, Zachary; Bellan, Paul

2011-11-01

188

Daily activity and light exposure levels for five species of lemurs at the Duke Lemur Center.  

PubMed

Light is the primary synchronizer of all biological rhythms, yet little is known about the role of the 24-hour luminous environment on nonhuman primate circadian patterns, making it difficult to understand the photic niche of the ancestral primate. Here we present the first data on proximate light-dark exposure and activity-rest patterns in free-ranging nonhuman primates. Four individuals each of five species of lemurs at the Duke Lemur Center (Eulemur mongoz, Lemur catta, Propithecus coquereli, Varecia rubra, and Varecia variegata variegata) were fitted with a Daysimeter-D pendant that contained light and accelerometer sensors. Our results reveal common as well as species-specific light exposure and behavior patterns. As expected, all five species were more active between sunrise and sunset. All five species demonstrated an anticipatory increase in their pre-sunrise activity that peaked at sunrise with all but V. rubra showing a reduction within an hour. All five species reduced activity during mid-day. Four of the five stayed active after sunset, but P. coquereli began reducing their activity about 2 hours before sunset. Other subtle differences in the recorded light exposure and activity patterns suggest species-specific photic niches and behaviors. The eventual application of the Daysimeter-D in the wild may help to better understand the adaptive evolution of ancestral primates. PMID:24318943

Rea, Mark S; Figueiro, Mariana G; Jones, Geoffrey E; Glander, Kenneth E

2014-01-01

189

Preparation and visible light photocatalytic activity of Ag/TiO?/graphene nanocomposite.  

PubMed

Great efforts have been made to develop efficient visible light-activated photocatalysts in recent years. In this work, a new nanocomposite consisting of anatase TiO(2), Ag, and graphene was prepared for use as a visible light-activated photocatalyst, which exhibited significantly increased visible light absorption and improved photocatalytic activity, compared with Ag/TiO(2) and TiO(2)/graphene nanocomposites. The increased absorption in visible light region is originated from the strong interaction between TiO(2) nanoparticles and graphene, as well as the surface plasmon resonance effect of Ag nanoparticles that are mainly adsorbed on the surface of TiO(2) nanoparticles. The highly efficient photocatalytic activity is associated with the strong adsorption ability of graphene for aromatic dye molecules, fast photogenerated charge separation due to the formation of Schottky junction between TiO(2) and Ag nanoparticles and the high electron mobility of graphene sheets, as well as the broad absorption in the visible light region. This work suggests that the combination of the excellent electrical properties of graphene and the surface plasmon resonance effect of noble metallic nanoparticles provides a versatile strategy for the synthesis of novel and efficient visible light-activated photocatalysts. PMID:21909581

Wen, Yanyuan; Ding, Hanming; Shan, Yongkui

2011-10-01

190

Program Converts VAX Floating-Point Data To UNIX  

NASA Technical Reports Server (NTRS)

VAX Floating Point to Host Floating Point Conversion (VAXFC) software converts non-ASCII files to unformatted floating-point representation of UNIX machine. This is done by reading bytes bit by bit, converting them to floating-point numbers, then writing results to another file. Useful when data files created by VAX computer must be used on other machines. Written in C language.

Alves, Marcos; Chapman, Bruce; Chu, Eugene

1996-01-01

191

Developing the ``Multiwavelength Astronomy: Galaxies in a Different Light'' Activity  

Microsoft Academic Search

``Multiwavelength Astronomy'' is designed to lead high school students to understand astronomers' use of different wavelengths in studying the nature of galaxies. When developing the activity we followed the NASA-funded Virtual Design Center guidelines. With the project rationale and standards- alignment analysis completed, we surveyed high school students from several classes about their knowledge and interest in topics related to

M. K. Hemenway; S. Jogee; K. Fricke; R. Worhatch; L. Ruberg

2008-01-01

192

Orexinergic signaling mediates light-induced neuronal activation in the dorsal raphe nucleus.  

PubMed

Seasonal affective disorder (SAD), a major depressive disorder recurring in the fall and winter, is caused by the reduction of light in the environment, and its depressive symptoms can be alleviated by bright light therapy. Both circadian and monoaminergic systems have been implicated in the etiology of SAD. However, the underlying neural pathways through which light regulates mood are not well understood. The present study utilized a diurnal rodent model, Arvicanthis niloticus, to explore the neural pathways mediating the effects of light on brain regions involved in mood regulation. Animals kept in constant darkness received light exposure in early subjective day, the time when light therapy is usually applied. The time course of neural activity following light exposure was assessed using Fos protein as a marker in the following brain regions/cells: the suprachiasmatic nucleus (SCN), orexin neurons in the perifornical-lateral hypothalamic area (PF-LHA) and the dorsal raphe nucleus (DRN). A light-induced increase in Fos expression was observed in orexin neurons and the DRN, but not in the SCN. As the DRN is densely innervated by orexinergic inputs, the involvement of orexinergic signaling in mediating the effects of light on the DRN was tested in the second experiment. The animals were injected with the selective orexin receptor type 1 (OXR1) antagonist SB-334867 prior to the light exposure. The treatment of SB-334867 significantly inhibited the Fos induction in the DRN. The results collectively point to the role of orexin neurons in mediating the effects of light on the mood-regulating monoaminergic areas, suggesting an orexinergic pathway that underlies light-dependent mood fluctuation and the beneficial effects of light therapy. PMID:22710065

Adidharma, W; Leach, G; Yan, L

2012-09-18

193

Effects of daytime light exposure on cognitive brain activity as measured by the ERP P300.  

PubMed

Exposure to light modulates not only human alertness but also cognitive functions. The present study examined the temporal dynamics of the effects of light exposure on cortical activity related to cognitive processes. Event-related potentials (ERPs) were measured while participants performed an auditory oddball task during exposure to short-, medium- or long-wavelength light or darkness. Experiments were conducted in the daytime. After a 10-min period of darkness, one of the three lights was presented for 28min. In the control condition, darkness was maintained for the entire session. The ERP component observed approximately 300ms after the onset of the target stimulus (P300) was analyzed. The amplitude of P300 was larger after 5-20min of exposure to short-wavelength light than at equivalent time points in the darkness. No differences were observed in the amplitude of P300 between the medium- or long-wavelength light condition and darkness at any time point. These results suggest that the amount of attentional resource allocated to the oddball task was increased by daytime exposure to short-wavelength light, and that following approximately 5min of exposure the impact of light on cortical activity related to cognitive processes was able to be detected. PMID:25447474

Okamoto, Yosuke; Nakagawa, Seiji

2015-01-01

194

A device to improve the SNR of the measurement of the positional floating reference point  

NASA Astrophysics Data System (ADS)

Previous studies have preliminarily validated the floating reference method and shown that it has the potential to improve the accuracy of non-invasive blood glucose sensing by Near-Infrared Spectroscopy. In order to make this method practical, it is necessary to precisely verify and measure the existence and variation features of the positional floating reference point. In this talk, a device which can precisely verify and measure the positional floating reference point is built. Since the light intensity of diffuse reflectance from the tested sample is very weak, a multipath detecting fibers system was built to improve signal-to-noise ratio. In this system, the fibers encircle the light source fiber which is regarded as the reference center of detecting fibers while they are moving. In addition, the position of each fiber is accurately controlled by manual translation stage to keep all detecting fibers always in the same radius around light source fiber. This ensures that received signal is coming from the same radial distance of light source. The variation of signal-to-noise ratio along with the different radial distance was investigated based on experiments. Results show that the application of this device could improve signal-to-noise ratio, and provide a new experimental method for the further study of positional floating reference point.

Jiang, Jingying; Rong, Xuzheng; Zhang, Hao; Xu, Kexin

2013-02-01

195

Genetics Home Reference: Floating-Harbor syndrome  

MedlinePLUS

... syndrome? Floating-Harbor syndrome is a disorder involving short stature, slowing of the mineralization of the bones (delayed ... deficiency ; disability ; gene ; inherited ; motor ; mutation ; philtrum ; protein ; short stature ; stature ; syndrome ; testes You may find definitions for ...

196

Advanced controls for floating wind turbines  

E-print Network

Floating Offshore Wind Turbines (FOWT) is a technology that stands to spearhead the rapid growth of the offshore wind energy sector and allow the exploration of vast high quality wind resources over coastal and offshore ...

Casanovas, Carlos (Casanovas Bermejo)

2014-01-01

197

Parametric design of floating wind turbines  

E-print Network

As the price of energy increases and wind turbine technology matures, it is evident that cost effective designs for floating wind turbines are needed. The next frontier for wind power is the ocean, yet development in near ...

Tracy, Christopher (Christopher Henry)

2007-01-01

198

Retinal Pigment Epithelial (RPE) Verification of melanin function as a light activated ROS scavenger  

E-print Network

;Verification of melanin function as a light activated ROS scavenger ABSTRACT Melanin is a heterogeneous and a scavenger of free radicals and reactive oxygen species (ROS). Heterogeneous melanin aggregates from Sepia-activated ROS scavenger to increasing cell viability. II #12; Anderson III #12

199

Gas transfer in floating-leaved plants  

Microsoft Academic Search

Pressurized gas transport with flow rates of 1.1 to 1.81 gas h-1 plant-1 have been detected in the floating-leaved aquatic macrophyte Euryale ferox on sunny days. The younger leaves gave the highest pressurization, but the gas flow was initiated mainly by the middle-aged leaves of the plants. The gas through-flow was shown to be highly beneficial for floating-leaved plants. It

W. Große; C. Bauch

1991-01-01

200

Floating assembly of diatom Coscinodiscus sp. microshells.  

PubMed

Diatoms have silica frustules with transparent and delicate micro/nano scale structures, two dimensional pore arrays, and large surface areas. Although, the diatom cells of Coscinodiscus sp. live underwater, we found that their valves can float on water and assemble together. Experiments show that the convex shape and the 40 nm sieve pores of the valves allow them to float on water, and that the buoyancy and the micro-range attractive forces cause the valves to assemble together at the highest point of water. As measured by AFM calibrated glass needles fixed in manipulator, the buoyancy force on a single floating valve may reach up to 10 ?N in water. Turning the valves over, enlarging the sieve pores, reducing the surface tension of water, or vacuum pumping may cause the floating valves to sink. After the water has evaporated, the floating valves remained in their assembled state and formed a monolayer film. The bonded diatom monolayer may be valuable in studies on diatom based optical devices, biosensors, solar cells, and batteries, to better use the optical and adsorption properties of frustules. The floating assembly phenomenon can also be used as a self-assembly method for fabricating monolayer of circular plates. PMID:22387476

Wang, Yu; Pan, Junfeng; Cai, Jun; Zhang, Deyuan

2012-03-30

201

Photodynamic treatment with BPD-MA (verteporfin) activated with light within different spectral ranges  

NASA Astrophysics Data System (ADS)

Benzoporphyrin derivative monoacid ring A [BPD-MA (verteporfin) or BPD], a second generation photosensitizer tested in clinical trials in combination with red light was compared for its PDT efficiency in vitro and in vivo upon activation with light in the UVA, blue and red spectral ranges. PDT efficiency, calculated based on the BPD absorption spectrum and spectral output of the different light sources, was compared with actual PDT efficiency determined in vitro and in vivo. Results obtained in an in vitro cytotoxicity assay, in which aliquots of murine P815 cells, pre-incubated for 1 h with BPD at 5 ng/mL, were exposed simultaneously to various light doses delivered within UVA, blue and red spectral ranges showed that in this test system PDT efficiency was governed by BPD absorption and light source emission spectra. Similar results were obtained in an in vitro BPD photobleaching test. Thus in vitro, values for calculated, theoretical PDT efficiency corresponded to the actual PDT efficiency. However, in vivo factors, such as depth of tissue penetration with light and localization of the target, had an important influence on PDT efficiency. In mouse models of skin photosensitivity and the cutaneous hypersensitivity immune response (CHS) assay, because of the thinness of mouse skin, PDT efficiency approximated the theoretical PDT efficiency, although blue light was somewhat more efficient in PDT than UVA, and red light was somewhat more efficient than blue or UVA. In a pig skin photosensitivity model, red light induced the highest skin response manifested by erythema and swelling, while blue light caused erythema and minimal swelling and UVA caused only erythema. These differences could be related to the thickness of pig skin and the depth of tissue penetration characteristic of each spectral range. Fluence rate was found to be an additional factor which modifies the effect of BPD and light. In conclusion, BPD can be efficiently activated with light within the UVA, blue and red spectral ranges. Moreover, light doses, deemed safe for red light, can be utilized with light of other spectral ranges, but only after a very careful evaluation of the conditions under which they were determined and the conditions under which they will be used.

Richter, Anna M.; Jain, Ashok K.; Canaan, Alice J.; Bower, Robert D.; North, Janice; Simkin, Guillermo O.; Levy, Julia G.

1997-12-01

202

Light-activated hypericin induces cellular destruction of nasopharyngeal carcinoma cells  

NASA Astrophysics Data System (ADS)

Hypericin from Hypericum perforatum plants shows an important promise in the photodynamic therapy on malignant tumor. The present study investigated that light-activated hypericin induced the cellular destruction of nasopharyngeal carcinoma cells. The result showed that hypericin resulted in a drug- and light-dose dependent cytotoxicity in the CNE-2 cells, meaning the photocytotoxicity of hypericin depends on both of the drug concentration (0 – 2.5 ?M) and light-doses (1 – 8 J/cm2). We further investigated the apoptosis of the CNE-2 cells 8 hours after photosensitization of hypericin using fluorescence microscopy with Hoechst 33258 staining. Flow cytometry with annexin V-FITC and PI staining was used to analyze early and late apoptosis. These data demonstrated that light-activated hypericin could significantly lead to the cellular destruction of the CNE-2 cells and induce early apoptosis as a prominent mode of cell death.

Xu, C. S.; Leung, A. W. N.

2010-01-01

203

Effect of light quality on rosmarinic acid content and antioxidant activity of sweet basil, Ocimum basilicum L  

Microsoft Academic Search

Rosmarinic acid (RA), one of the main phenolic compounds in sweet basil (Ocimum basilicum L.), has antiviral, antimicrobial, and anti-inflammatory pharmacological properties. As recent studies have shown that UV-B and blue light irradiation stimulate phenylpropanoid biosynthesis, we determined whether light conditions affect RA content and antioxidant activity. Both antioxidant activity and phenolic content were increased by continuous white light irradiation.

Tomomi Shiga; Kazuhiro Shoji; Hiroaki Shimada; Shin-nosuke Hashida; Fumiyuki Goto; Toshihiro Yoshihara

204

A light-inducible CRISPR-Cas9 system for control of endogenous gene activation.  

PubMed

Optogenetic systems enable precise spatial and temporal control of cell behavior. We engineered a light-activated CRISPR-Cas9 effector (LACE) system that induces transcription of endogenous genes in the presence of blue light. This was accomplished by fusing the light-inducible heterodimerizing proteins CRY2 and CIB1 to a transactivation domain and the catalytically inactive dCas9, respectively. The versatile LACE system can be easily directed to new DNA sequences for the dynamic regulation of endogenous genes. PMID:25664691

Polstein, Lauren R; Gersbach, Charles A

2015-03-01

205

Temperature and light effects on the circadian rhythm and locomotory activity of the plains garter snake (Thamnophis radix hayendi)  

Microsoft Academic Search

The Locomotory activity of the Plains Garter snake was determined under L\\/D: 12\\/12 conditions at five constant temperatures and three light intensities during the light period. The snakes were diurnal at low temperatures with nocturnal activity increasing in various amounts at higher temperatures. The different light intensities had relatively small effects on the activity rhythm.Activity was recorded under four constant

C. Heckrotte

1975-01-01

206

Light activation of the LOV protein vivid generates a rapidly exchanging dimer.  

PubMed

The fungal photoreceptor Vivid (VVD) plays an important role in the adaptation of blue-light responses in Neurospora crassa. VVD, an FAD-binding LOV (light, oxygen, voltage) protein, couples light-induced cysteinyl adduct formation at the flavin ring to conformational changes in the N-terminal cap (Ncap) of the VVD PAS domain. Size-exclusion chromatography (SEC), equilibrium ultracentrifugation, and static and dynamic light scattering show that these conformational changes generate a rapidly exchanging VVD dimer, with an expanded hydrodynamic radius. A three-residue N-terminal beta-turn that assumes two different conformations in a crystal structure of a VVD C71V variant is essential for light-state dimerization. Residue substitutions at a critical hinge between the Ncap and PAS core can inhibit or enhance dimerization, whereas a Tyr to Trp substitution at the Ncap-PAS interface stabilizes the light-state dimer. Cross-linking through engineered disulfides indicates that the light-state dimer differs considerably from the dark-state dimer found in VVD crystal structures. These results verify the role of Ncap conformational changes in gating the photic response of N. crassa and indicate that LOV-LOV homo- or heterodimerization may be a mechanism for regulating light-activated gene expression. PMID:18553928

Zoltowski, Brian D; Crane, Brian R

2008-07-01

207

Light activation of the LOV protein Vivid generates a rapidly exchanging dimer†‡  

PubMed Central

The fungal photoreceptor Vivid (VVD) plays an important role in the adaptation of blue-light responses in Neurospora crassa. VVD, an FAD-binding LOV (Light, Oxygen, Voltage) protein, couples light-induced cysteinyl-adduct formation at the flavin ring to conformational changes in the N-terminal cap (Ncap) of the VVD PAS domain. Size-exclusion chromatography (SEC), equilibrium ultracentrifugation, and static and dynamic light scattering show that these conformational changes generate a rapidly exchanging VVD dimer, with an expanded hydrodynamic radius. A three-residue N-terminal ?-turn that assumes two different conformations in a crystal structure of a VVD C71V variant is essential for light-state dimerization. Residue substitutions at a critical hinge between the Ncap and PAS core can inhibit or enhance dimerization, whereas a Tyr to Trp substitution at the Ncap-to-PAS interface stabilizes the light-state dimer. Cross-linking through engineered disulfides indicates that the light-state dimer differs considerably from the dark-state dimer found in VVD crystal structures. These results verify the role of Ncap conformational changes in gating the photic response of Neurospora crassa, and indicate that LOV:LOV homo or hetero dimerization may be a mechanism for regulating light-activated gene expression. PMID:18553928

Zoltowski, Brian D.; Crane, Brian R.

2009-01-01

208

Pattern of stylet penetration activity by Homalodisca vitripennis (Hemiptera: Cicadellidae) adults in relation to environmental temperature and light conditions  

Technology Transfer Automated Retrieval System (TEKTRAN)

Effects of ambient spring air temperature and light intensity on stylet penetration activities of the glassy-winged sharpshooter, Homalodisca vitripennis (Germar) were studied outdoors, at ambient light and temperatures, using an electrical penetration graph (EPG). EPG waveforms representing saliva...

209

Visible light photocatalytic activity of TiO2 nanoparticles hybridized by conjugated derivative of polybutadiene  

NASA Astrophysics Data System (ADS)

A series of conjugated polymer/TiO2 (CP/TiO2) nanocomposites were prepared from TiO2 and commercial polybutadiene. The as-prepared CP/TiO2 nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), Raman Spectroscopy, UV-vis diffuse reflectance spectroscopy (UV-vis DRS), and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities of CP/TiO2 nanocomposites were investigated by monitoring the degradation of methyl orange aqueous solution under visible light irradiation. The effects of preparation conditions (such as the mass ratio of PB to TiO2 in suspensions for PB/TiO2 preparation, heat-treatment temperature and time) of CP/TiO2 nanocomposites on their visible light photocatalytic activity were investigated. The results show that the CP/TiO2 nanocomposites have excellent visible light photocatalytic activity. As the content of conjugated polymer on the TiO2 surface, heat-treatment temperature and time increase, the visible light photocatalytic activity increases at first and then decreases. The visible light photocatalytic mechanism of the CP/TiO2 nanocomposites has been discussed.

Liu, Guoquan; Liu, Longchen; Song, Jinran; Liang, Jiudi; Luo, Qingzhi; Wang, Desong

2014-05-01

210

The effect of multiple sequential light sources to activate aminolevulinic Acid in the treatment of actinic keratoses: a retrospective study.  

PubMed

There is a lack of research regarding the sequential use of multiple light sources for topical 5-aminolevulinic acid activation in photodynamic therapy for actinic keratosis. This study evaluated 5-aminolevulinic acid-photodynamic therapy for actinic keratosis using blue light combined with red light, pulsed dye laser, and/or intense pulsed light in a retrospective fashion. Field-directed 5-aminolevulinic acid-photodynamic therapy was performed with blue light only, blue light + pulsed dye laser, blue light + intense pulsed light, blue light + pulsed dye laser + intense pulsed light, or blue light + red light + pulsed dye laser + intense pulsed light for nonhyperkeratotic actinic keratoses of face, scalp, or upper trunk. Blue light + intense pulsed light + pulsed dye laser produced greater patient-reported improvement in actinic keratoses than blue light or blue light + intense pulsed light and greater subject-reported improvement in overall skin quality than blue light + intense pulsed light. The addition of red light led to no further benefit in either outcome measure. Photodynamic therapy with multiple, sequential laser and light sources led to greater patient-graded improvement in actinic keratoses than that with a single light source (blue light), without significant differences in post-treatment adverse events. However, the small, widely disparate number of patients between groups and follow-up times between patients, as well as retrospective assessments based on subjective patient recall, severely limit the significance of these findings. Nevertheless, the results raise interesting questions regarding the use of multiple light and laser sources for photodynamic therapy of actinic keratoses and warrant further research with a prospective, randomized, controlled study. PMID:25276272

Friedmann, Daniel P; Goldman, Mitchel P; Fabi, Sabrina G; Guiha, Isabella

2014-09-01

211

Diacylglycerol activates the light-dependent channel TRP in the photosensitive microvilli of Drosophila melanogaster photoreceptors.  

PubMed

Drosophila light-dependent channels, TRP and TRPL, reside in the light-sensitive microvilli of the photoreceptor's rhabdomere. Phospholipase C mediates TRP/TRPL opening, but the gating process remains unknown. Controversial evidence has suggested diacylglycerol (DAG), polyunsaturated fatty acids (PUFAs, a DAG metabolite), phosphatidylinositol bisphosphate (PIP2), and H(+) as possible channel activators. We tested each of them directly in inside-out TRP-expressing patches excised from the rhabdomere, making use of mutants and pharmacology. When patches were excised in darkness TRP remained closed, while when excised under illumination it stayed constitutively active. TRP was opened by DAG and silenced by ATP, suggesting DAG-kinase (DGK) involvement. The ATP effect was abolished by inhibiting DGK and in the rdgA mutant, lacking functional DGK, implicating DGK. DAG activated TRP even in the presence of a DAG-lipase inhibitor, inconsistent with a requirement of PUFAs in opening TRP. PIP2 had no effect and acidification, pH 6.4, activated TRP irreversibly, unlike the endogenous activator. Complementary liquid-chromatography/mass-spectrometry determinations of DAG and PUFAs in membranes enriched in rhabdomere obtained from light- and dark-adapted eyes showed light-dependent increment in six DAG species and no changes in PUFAs. The results strongly support DAG as the endogenous TRP agonist, as some of its vertebrate TRPC homologs of the same channel family. PMID:24806693

Delgado, Ricardo; Muñoz, Yorka; Peña-Cortés, Hugo; Giavalisco, Patrick; Bacigalupo, Juan

2014-05-01

212

Effects of hydroxyl radical scavengers KCN and CO on ultraviolet light-induced activation of crude soluble guanylate cyclase  

SciTech Connect

The crude soluble guanylate cyclase (GC) from bovine mesenteric artery was stimulated by ultraviolet (UV) light (366 nm). Addition of free radical scavengers, dimethylsulfoxide or superoxide dismutase and/or catalase to the GC assay did not abolish the stimulatory effect of UV light. On the contrary, the UV light-induced activation was enhanced in the presence of these scavengers. KCN (1 mM) did not affect the UV light-induced activation, while 0.1 mM of CO potentiated the activation. These results may indicate that UV light is operating through a direct interaction with the ferrous form of the GC-heme.

Karlsson, J.O.; Axelsson, K.L.; Andersson, R.G.

1985-01-01

213

On the electrostatic behavior of floating nanoconductors  

NASA Astrophysics Data System (ADS)

In this work, the electrostatic behaviour of nanometer-sized metallic floating conductors embedded in a dielectric medium has been investigated. First of all, we present a semi-analytical approach based on Green functions and show its excellent quantitative agreement with well known finite element methods concerning electrostatic computations. Then, we compare floating potential values obtained by numerical simulation with an approach based on an equivalent capacitor circuit. We show that the latter is inappropriate for sub-100 nm wide floating electrodes when the parallel plates approximation (PPA) is used to estimate the coupling capacitance values because of lateral coupling effects. Nevertheless, we finally show that these coupling capacitances can be easily extracted to predict the electrostatic potential of metallic nano-dots with the same accuracy than with a direct numerical computation. We finally propose a figure of merit to estimate the validity of the PPA. These results are useful to predict the floating potential of future generations of non-volatile-memories using metallic dots. Moreover they can be used to give a first estimation of the floating potential in a self consistent Poisson-Schrödinger resolution when considering semiconductor nanocrystals.

Deleruyelle, D.; Micolau, G.

2008-01-01

214

Floating seal system for rotary devices  

DOEpatents

This invention relates to a floating seal system for rotary devices to reduce gas leakage around the rotary device in a duct and across the face of the rotary device to an adjacent duct. The peripheral seal bodies are made of resilient material having a generally U-shaped cross section wherein one of the legs is secured to a support member and the other of the legs forms a contacting seal against the rotary device. The legs of the peripheral seal form an extended angle of intersection of about 10[degree] to about 30[degree] in the unloaded condition to provide even sealing forces around the periphery of the rotary device. The peripheral seal extends around the periphery of the support member except where intersected by radial seals which reduce gas leakage across the face of the rotary device and between adjacent duct portions. The radial seal assembly is fabricated from channel bars, the smaller channel bar being secured to the divider of the support member and a larger inverted rigid floating channel bar having its legs freely movable over the legs of the smaller channel bar forming therewith a tubular channel. A resilient flexible tube is positioned within the tubular channel for substantially its full length to reduce gas leakage across the tubular channel. A spacer extends beyond the face of the floating channel near each end of the floating channel a distance to provide desired clearance between the floating channel and the face of the rotary device. 5 figs.

Banasiuk, H.A.

1983-08-23

215

Characterization and activity of visible-light driven TiO2 photocatalyst doped with tungsten.  

PubMed

This research aimed to expand the activity of TiO(2) down to the visible light region by modifying the sol-gel conditions and doping with tungsten. The optimum conditions for calcination temperature, acid type, and heating rate were 200°C, HNO(3), and 1°C/min, respectively. The undoped TiO(2) synthesized under these conditions could significantly absorb the visible light whereas the commercial Degussa P-25 could not. The absorptivity decreased sequentially as the wavelength increased from 400 to 700 nm. Within 6 h of 2-W blue-light illumination, 23% of 0.1 mM 2-chlorophenol was removed. The XRD result showed that the crystalline was anatase phase. The visible-light absorption property of the TiO(2) became even better when doped with tungsten. At the optimum W to TiO(2) ratio of 0.5%, the degradation of 0.1 mM 2-chlorophenol increased to 53% indicating a higher photocatalytic activity. Both crystalline and amorphous TiO(2) could exhibit the photocatalytic activity under the visible light region. PMID:21045341

Putta, T; Lu, M C; Anotai, J

2010-01-01

216

Improved low-power semiconductor diode lasers for light activation of pharmaceutical agents  

NASA Astrophysics Data System (ADS)

In photodynamic therapy, a photosensitizing dye is injected into the patient and the die accumulates in tumor tissue. The cancer cells are then destroyed by absorbing light of a specific wavelength, usually around 630 nm. One of the strong advantages of this therapy is that it destroys only malignant cells and causes less morbidity than standard treatments like surgery and radiotherapy. There are several other techniques that also utilize light activation of pharmaceutical agents in treatment of cancers such as breast cancer. One method of supplying this light activation is through the use of diode lasers, which are constantly finding new application in all fields of medicine. However these lasers tend to be limited by their high cost per watt and multiple wavelength output. Cryogenically cooling such lasers provides higher power output and therefore longer device lifetime. We report quantification of these results from laser power meter and photospectrometer data.

Lee, Susanne M.; Mueller, Eduard K.; Van de Workeen, Brian C.; Mueller, Otward M.

2001-05-01

217

Effect of metals on the catalytic activity of sulfated zirconia for light naphtha isomerization  

Microsoft Academic Search

We studied on the function of the metal in the sulfated zirconia(SO42-\\/ZrO2) catalyst for the isomerization reaction of light paraffins. The addition of Pt to the SO42-\\/ZrO2 carrier could keep the high catalytic activity. The improvement in this isomerization activity is because Pt promotes removal of the coke precursor deposited on the catalyst surface. Though this catalytic function was observed

Katsuya Watanabe; Takahito Kawakami; Koji Baba; Nobuyasu Oshio; Takao Kimura

2005-01-01

218

Hierarchical nanostructures of ?-TaON flowers for enhanced visible light driven photocatalytic activities.  

PubMed

Hierarchical nanostructures of single phase ?-TaON flowers have been successfully synthesized using a simple wet-chemical route in addition to subsequent thermal nitridation. These flower-like particles exhibit an obvious improvement in visible-light-driven photocatalytic activity. PMID:25567373

Wang, Zheng; Xie, Keng; Zhao, Lei; Zhang, Bangsheng

2015-01-27

219

Myosin Light Chain-activating Phosphorylation Sites Are Required for Oogenesis in Drosophila  

Microsoft Academic Search

The Drosophila spaghetti squash ( sqh ) gene encodes the regulatory myosin light chain (RMLC) of nonmuscle myosin II. Biochemical analysis of verte- brate nonmuscle and smooth muscle myosin II has es- tablished that phosphorylation of certain amino acids of the RMLC greatly increases the actin-dependent myosin ATPase and motor activity of myosin in vitro. We have assessed the in

Pascale Jordan; Roger Karess

2010-01-01

220

Efficient blue organic light-emitting diodes employing thermally activated delayed  

E-print Network

Efficient blue organic light-emitting diodes employing thermally activated delayed fluorescence. However, the efficiencies of blue TADF OLEDs are still low at high luminance, limiting full-colour display. Here, we report a blue OLED containing a 9,10-dihydroacridine/diphenylsulphone derivative that has

Cai, Long

221

Effect of sprouting and light cycle on antioxidant activity of Brassica oleracea varieties.  

PubMed

The antioxidant activity of sprouts from four Brassica oleracea varieties was evaluated using "in vitro" methods (total phenolic and flavonoid content; radical scavenging assays: DPPH, hydroxyl and peroxyl; and Ferrous Ion-chelating Ability Assay). Light cycles and sprouting influenced the potential antioxidant activity of sprouts and significant differences were observed between varieties. Generally, antioxidant activity decreased with sprouting and increased in the presence of light, whose discriminant effect was highly significant (P<0.001). Red cabbage sprouts produced under light cycles showed the highest antioxidant activity (57.11 ?g mL(-1) Ferrous Ion-chelating Ability, 221.46 ?g mL(-1) Hydroxyl radical scavenging, 279.02 ?g mL(-1) Peroxyl radical scavenging). Among the traditional Portuguese brassica varieties, Penca cabbage sprouts produced under light presented higher antioxidant capacity, and also higher phenolic and flavonoid content (54.04 mg GAEg(-1) d.w. extract and 21.33 QEg(-1) d.w. extract, respectively) than Galega kale. The phenolic content of Brassica sprouts had a significant contribution to the antioxidant capacity. PMID:25038690

Vale, Ana Paula; Cidade, Honorina; Pinto, Madalena; Oliveira, M Beatriz P P

2014-12-15

222

Vibration characteristics of floating slab track  

NASA Astrophysics Data System (ADS)

Coupled equilibrium equations of suspended wheels and floating slab track system were solved with the fourth-order Runge-Kutta method to obtain the deflections, vibration velocities, and wheel-rail contact forces. The program was validated through several aspects. Cases with various vehicle speed, slab mass, and stiffness of slab bearing were analyzed to reveal the effects of slab bearing on track responses. The correlation between wheel-rail resonance and train speed was also discussed. It was found that rail deflections increase significantly as train speed increases. Although large slab mass may lower tuning frequency, it could also result in higher wheel-rail contact force and rail deflections. The floating slab track is effective in isolating loading above 10 Hz, which might present in some railway sections with irregularities. Adopting floating slab track for vibration control for environment along the railway may cause concerns about ride quality and track damages.

Kuo, Chen-Ming; Huang, Cheng-Hao; Chen, Yi-Yi

2008-11-01

223

Floating zone melting of cadmium telluride  

NASA Technical Reports Server (NTRS)

To produce superior crystals of cadmium telluride, floating zone melting in space has been proposed. Techniques required for floating zone melting of cadmium telluride are being developed. We have successfully float-zoned cadmium telluride on earth using square rods. A resistance heater was constructed for forming the molten zone. Evaporation of the molten zone was controlled by adding excess cadmium to the growth ampoule combined with heating of the entire ampoule. An effective method to hold the feed rod was developed. Slow rotation of the growth ampoule was proven experimentally to be necessary to achieve a complete symmetric molten zone. Most of the resultant cylindrical rods were single crystals with twins. Still needed is a suitable automatic method to control the zone length. We tried a fiber optical technique to control the zone length, but experiments showed that application of this technique to automate zone length control is unlikely to be successful.

Chang, Wen-Ming; Regel, L. L.; Wilcox, W. R.

1992-01-01

224

46 CFR 160.027-3 - Additional requirements for life floats.  

Code of Federal Regulations, 2013 CFR

... false Additional requirements for life floats. 160.027-3 Section 160...AND APPROVAL LIFESAVING EQUIPMENT Life Floats for Merchant Vessels § 160.027-3 Additional requirements for life floats. (a) Each life float...

2013-10-01

225

46 CFR 160.027-3 - Additional requirements for life floats.  

Code of Federal Regulations, 2011 CFR

... false Additional requirements for life floats. 160.027-3 Section 160...AND APPROVAL LIFESAVING EQUIPMENT Life Floats for Merchant Vessels § 160.027-3 Additional requirements for life floats. (a) Each life float...

2011-10-01

226

46 CFR 160.027-3 - Additional requirements for life floats.  

Code of Federal Regulations, 2012 CFR

... false Additional requirements for life floats. 160.027-3 Section 160...AND APPROVAL LIFESAVING EQUIPMENT Life Floats for Merchant Vessels § 160.027-3 Additional requirements for life floats. (a) Each life float...

2012-10-01

227

46 CFR 160.027-3 - Additional requirements for life floats.  

Code of Federal Regulations, 2010 CFR

... false Additional requirements for life floats. 160.027-3 Section 160...AND APPROVAL LIFESAVING EQUIPMENT Life Floats for Merchant Vessels § 160.027-3 Additional requirements for life floats. (a) Each life float...

2010-10-01

228

46 CFR 160.027-3 - Additional requirements for life floats.  

Code of Federal Regulations, 2014 CFR

... false Additional requirements for life floats. 160.027-3 Section 160...AND APPROVAL LIFESAVING EQUIPMENT Life Floats for Merchant Vessels § 160.027-3 Additional requirements for life floats. (a) Each life float...

2014-10-01

229

'Caged' peptide nucleic acids activated by red light in a singlet oxygen mediated process.  

PubMed

Common 'caged' nucleic acid binders, which can be applied for temporal and spatial control of gene expression, are activated by high energy light (<450 nm). The light of this type is damaging to cells and is strongly absorbed by cellular components. Therefore, shifting the triggering light to the visible region (>550 nm) is highly desirable. Herein we report on a cyclic peptide nucleic acid (PNA), whose backbone contains a 9,10-dialkoxy-substituted anthracene linker. The sequence of this compound was selected to be complementary to a representative microRNA (miR-92). We demonstrated that the cyclic PNA does not bind complementary nucleic acids and is, correspondingly, 'caged'. Its uncaging can be conducted by its exposure to red light (635 nm) in the presence of pyropheophorbide-a. The latter process is mediated by singlet oxygen ((1)O2), which cleaves the 9,10-dialcoxyanthracene linker within the PNA with formation of a linear PNA, an efficient binder of the complementary ribonucleic acid. This is the first example of a red light-activated, 'caged' peptide nucleic acid. PMID:24268552

König, Sandra G; Mokhir, Andriy

2013-12-15

230

The syntactic and semantic roots of floating quantification  

E-print Network

Through the study of floating quantifiers in a variety of languages, I demonstrate that floating quantification is not a uniform phenomenon and outline a series of puzzles that force us to adopt a two-part analysis. I argue ...

Fitzpatrick, Justin Michael

2006-01-01

231

14 CFR 27.521 - Float landing conditions.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 false Float landing conditions. 27.521 Section...Water Loads § 27.521 Float landing conditions. If certification...equal to that determined for wheel landing gear): (a) Up-load conditions...

2011-01-01

232

14 CFR 27.521 - Float landing conditions.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 false Float landing conditions. 27.521 Section...Water Loads § 27.521 Float landing conditions. If certification...equal to that determined for wheel landing gear): (a) Up-load conditions...

2010-01-01

233

Improvements in floating point addition/subtraction operations  

DOEpatents

Apparatus is described for decreasing the latency time associated with floating point addition and subtraction in a computer, using a novel bifurcated, pre-normalization/post-normalization approach that distinguishes between differences of floating point exponents.

Farmwald, P.M.

1984-02-24

234

Study on the activation of styrene-based shape memory polymer by medium-infrared laser light  

SciTech Connect

This paper demonstrates the feasibility of shape memory polymer (SMP) activation by medium-infrared laser light. Medium-infrared light is transmitted by an optical fiber embedded in the SMP matrix, and the shape recovery process and temperature distribution are recorded by an infrared camera. Light-induced SMP exhibits potential applications in biomedicines and flexible displays.

Leng Jinsong; Yu Kai; Lan Xin [Center for Composite Materials and Structures, Harbin Institute of Technology, HeiLongJiang 150001 (China); Zhang Dawei [Center for Composite Materials and Structures, Harbin Institute of Technology, HeiLongJiang 150001 (China); Material Science and Engineering College, Northeast Forestry University, HeiLongJiang 150040 (China); Liu Yanju [Department of Astronautical Science and Mechanics, Harbin Institute of Technology, HeiLongJiang 150001 (China)

2010-03-15

235

Light-Triggered Modulation of Cellular Electrical Activity by Ruthenium Diimine Nanoswitches  

PubMed Central

Ruthenium diimine complexes have previously been used to facilitate light-activated electron transfer in the study of redox metalloproteins. Excitation at 488 nm leads to a photoexcited state, in which the complex can either accept or donate an electron, respectively, in the presence of a soluble sacrificial reductant or oxidant. Here, we describe a novel application of these complexes in mediating light-induced changes in cellular electrical activity. We demonstrate that RubpyC17 ([Ru(bpy)2(bpy-C17)]2+, where bpy is 2,2?-bipyridine and bpy-C17 is 2,2?-4-heptadecyl-4?-methyl-bipyridine), readily incorporates into the plasma membrane of cells, as evidenced by membrane-confined luminescence. Excitable cells incubated in RubpyC17 and then illuminated at 488 nm in the presence of the reductant ascorbate undergo membrane depolarization leading to firing of action potentials. In contrast, the same experiment performed with the oxidant ferricyanide, instead of ascorbate, leads to hyperpolarization. These experiments suggest that illumination of membrane-associated RubpyC17 in the presence of ascorbate alters the cell membrane potential by increasing the negative charge on the outer face of the cell membrane capacitor, effectively depolarizing the cell membrane. We rule out two alternative explanations for light-induced membrane potential changes, using patch clamp experiments: (1) light-induced direct interaction of RubpyC17 with ion channels and (2) light-induced membrane perforation. We show that incorporation of RubpyC17 into the plasma membrane of neuroendocrine cells enables light-induced secretion as monitored by amperometry. While the present work is focused on ruthenium diimine complexes, the findings point more generally to broader application of other transition metal complexes to mediate light-induced biological changes. PMID:23419103

2013-01-01

236

Promotion of Sink Activity of Developing Rose Shoots by Light 1  

PubMed Central

Holding young rose shoots (Rosa hybrida cv. Marimba) in darkness while the rest of the plant was in light reduced the amount of 14C assimilates recovered from the darkened shoot by half. Relative specific activity of the shoot tip grown in light was 13.5 times greater than that of the darkened one. The flower bud at the shoot tip degenerated in darkness and died. Shoots 2 to 3 centimeters long, after flower initiation, were most sensitive to the dark treatment. The degeneration is a gradual and reversible process in the first 8 days of darkness, followed by irreversible damage and atrophy. Darkening enhanced the ability of the young leaves to compete for the available assimilates over that of the darkened shoot tip. The enhancement of the mobilizing ability of the shoot tip by light is independent of photosynthesis since spraying with 3-(3,4-dichlorophenyl)-1,1-dimethylurea or holding shoots in a CO2-free atmosphere did not diminish the promoting effect of light on flower bud development or assimilate import. The possibility that light exerts its effect by photoproduction of ATP was also excluded inasmuch as no differences were found in ATP levels of shoot tips held in darkness and those held in light. PMID:16661566

Mor, Yoram; Halevy, Abraham H.

1980-01-01

237

Integrated light sources based on self-formed polymer waveguide doped with active medium  

NASA Astrophysics Data System (ADS)

The polymer-based photonic devices have promise as optical components integrated in convenient microchip systems because of ease in the deposition and microfabrication of polymer materials. Furthermore, since the polymers can be easily doped with luminescent materials such as organic dyes, the organic light source devices are also considerable as the integrated optical components. Especially the self-formation method of the fiber type waveguide using the dyedoped photopolymers, called as self-written active (SWA) waveguide technique, brings a simple fabrication scheme of the light sources integrated in the polymer photonic circuit. It has been demonstrated that an in-line optical amplifier and a Fabry-Perot type lasing cavity can be obtained by using the SWA waveguide technique. In this study we have employed this technique to fabricate an incoherent light source with a wideband emission. A serially cascaded SWA waveguide doped with the different organic dyes could be fabricated with a single exposure process. The cascaded SWA waveguide could act as an incoherent light source under UV light irradiation. This device can be expected as a probing light source for the label-free microchip system, which would be available for the biological sensing, environmental measurements, and medical diagnosis.

Sugimoto, S.; Kawaguchi, T.; Yamashita, K.

2012-06-01

238

Characterization of nucleoside triphosphatase activity in isolated pea nuclei and its photoreversible regulation by light  

NASA Technical Reports Server (NTRS)

A nucleoside triphosphatase (NTPase) present in highly purified preparations of pea nuclei was partially characterized. The activity of this enzyme was stimulated by divalent cations (Mg2+ = Mn2+ > Ca2+), but was not affected by the monovalent cations, Na+ and K+. The Mg(2+)-dependent activity was further stimulated by concentrations of Ca2+ in the low micromolar range. It could catalyze the hydrolysis of ATP, GTP, UTP, and CTP, all with a pH optimum of 7.5. The nuclear NTPase activity was not inhibited by vanadate, oligomycin, or nitrate, but was inhibited by relatively low concentrations of quercetin and the calmodulin inhibitor, compound 48/80. The NTPase was stimulated more than 50% by red light, and this effect was reversed by subsequent irradiation with far-red light. The photoreversibility of the stimulation indicated that the photoreceptor for this response was phytochrome, an important regulator of photomorphogenesis and gene expression in plants.

Chen, Y. R.; Roux, S. J.

1986-01-01

239

Photochemotherapy of intimal hyperplasia using psoralen activated by uv light in porcine model  

NASA Astrophysics Data System (ADS)

Psoralen activated by UVA light (PUVA) was investigated as a means of inhibiting smooth muscle cell proliferation resulting from balloon injury. Twenty kilogram domestic swine were anesthetized and underwent balloon angioplasty to create a 133% overstretch injury. Assignments of treatment and control were randomized between the left anterior descending (LAD) and circumflex (LCX) coronaries arteries. The animals were given with 5 mg/kg of 8- methoxypsoralen eternally. Treatment vessels received 600 mJ/cm2 of 364 nm light during balloon inflation to activate the psoralen. Control vessels received drug and balloon injury only. Serum was obtained during the light delivery to assess psoralen levels. At 30 days, animals were sacrificed and the coronary arteries perfusion fixed. Five sections per vessel were analyzed morphometrically to determine percent intimal area and extent of injury. The restenosis injury index was 0.21 plus or minus .02 in treatment vessels and 0.14 plus or minus .01 in the controls with a p-value less than .02. In this large animal model of balloon angioplasty injury, psoralen activated by ultraviolet light increased intimal hyperplasia.

Buckley, Lisa A.; Gregory, Kenton W.; Bahlman, Deborah T.; Shangguan, HanQun; Fahrenbach, Henner; Rosenthal, Eli; Block, Peter C.

1996-05-01

240

Human Cryptochrome-1 Confers Light Independent Biological Activity in Transgenic Drosophila Correlated with Flavin Radical Stability  

PubMed Central

Cryptochromes are conserved flavoprotein receptors found throughout the biological kingdom with diversified roles in plant development and entrainment of the circadian clock in animals. Light perception is proposed to occur through flavin radical formation that correlates with biological activity in vivo in both plants and Drosophila. By contrast, mammalian (Type II) cryptochromes regulate the circadian clock independently of light, raising the fundamental question of whether mammalian cryptochromes have evolved entirely distinct signaling mechanisms. Here we show by developmental and transcriptome analysis that Homo sapiens cryptochrome - 1 (HsCRY1) confers biological activity in transgenic expressing Drosophila in darkness, that can in some cases be further stimulated by light. In contrast to all other cryptochromes, purified recombinant HsCRY1 protein was stably isolated in the anionic radical flavin state, containing only a small proportion of oxidized flavin which could be reduced by illumination. We conclude that animal Type I and Type II cryptochromes may both have signaling mechanisms involving formation of a flavin radical signaling state, and that light independent activity of Type II cryptochromes is a consequence of dark accumulation of this redox form in vivo rather than of a fundamental difference in signaling mechanism. PMID:22427812

Vieira, Jacqueline; Jones, Alex R.; Danon, Antoine; Sakuma, Michiyo; Hoang, Nathalie; Robles, David; Tait, Shirley; Heyes, Derren J.; Picot, Marie; Yoshii, Taishi; Helfrich-Förster, Charlotte; Soubigou, Guillaume; Coppee, Jean-Yves; Klarsfeld, André; Rouyer, Francois; Scrutton, Nigel S.; Ahmad, Margaret

2012-01-01

241

Lightening up Light Therapy: Activation of Retrograde Signaling Pathway by Photobiomodulation.  

PubMed

Photobiomodulation utilizes monochromatic (or quasimonochromatic) light in the electromagnetic region of 600?1000 nm for the treatment of soft tissues in a nondestructive and nonthermal mode. It is conceivable that photobiomodulation is based upon the ability of the light to alter cell metabolism as it is absorbed by general hemoproteins and cytochrome c oxidase (COX) in particular. Recently it has been suggested radiation of visible and infrared (IR) activates retrograde signaling pathway from mitochondria to nucleus. In this review, the role of COX in the photobiomodulation will be discussed. Further a possible role of water as a photoreceptor will be suggested. PMID:25489415

Kim, Hong Pyo

2014-11-01

242

Taming the flow of light via active magneto-optical impurities  

NASA Astrophysics Data System (ADS)

We demonstrate that the interplay of a magneto-optical layer sandwiched between two judiciously balanced gain and loss layers which are both birefringent with misaligned in-plane anisotropy, induces unidirectional electromagnetic modes. Embedding one such optically active non-reciprocal unit between a pair of birefringent Bragg reflectors, results in an exceptionally strong asymmetry in light transmission. Remarkably, such asymmetry persists regardless of the incident light polarization. This photonic architecture may be used as the building block for chip-scale non-reciprocal devices such as optical isolators and circulators.

Kalish, Samuel; Ramezani, Hamidreza; Lin, Zin; Kottos, Tsampikos; Kovanis, Vassilios; Vitebskiy, Ilya

2013-03-01

243

The antimicrobial properties of light-activated polymers containing methylene blue and gold nanoparticles.  

PubMed

We report the formation of polysiloxane polymers containing embedded methylene blue and gold nanoparticles incorporated by a swell-encapsulation-shrink method. These polymers show significant antimicrobial activity against methicillin-resistant Staphylococcus aureus and Escherichia coli with up to a 3.5 log(10) reduction in the viable count when exposed for 5 min to light from a low power 660 nm laser. The bacterial kill is due to the light-induced production of singlet oxygen and other reactive oxygen species by the methylene blue. Interestingly, the presence of 2 nm gold nanoparticles significantly enhanced the ability of the methylene blue to kill bacteria. PMID:18838166

Perni, Stefano; Piccirillo, Clara; Pratten, Jonathan; Prokopovich, Polina; Chrzanowski, Wojciech; Parkin, Ivan P; Wilson, Michael

2009-01-01

244

High-efficiency white organic light-emitting diodes using thermally activated delayed fluorescence  

NASA Astrophysics Data System (ADS)

White organic light-emitting diodes (WOLEDs) have attracted much attention recently, aimed for next-generation lighting sources because of their high potential to realize high electroluminescence efficiency, flexibility, and low-cost manufacture. Here, we demonstrate high-efficiency WOLED using red, green, and blue thermally activated delayed fluorescence materials as emissive dopants to generate white electroluminescence. The WOLED has a maximum external quantum efficiency of over 17% with Commission Internationale de l'Eclairage coordinates of (0.30, 0.38).

Nishide, Jun-ichi; Nakanotani, Hajime; Hiraga, Yasuhide; Adachi, Chihaya

2014-06-01

245

Influence of softening test and light-activation protocols on resin composite polymer structure  

PubMed Central

Objective: This study analyzed the influences of the light-activation protocol and softening test on the degree of conversion (DC) and Knoop Hardness (KHN) of a microhybrid resin composite. Materials and Methods: Filtek Z250 (3M ESPE) was light-activated with a third-generation light-emitting diode (Valo Ultradent) by three protocols – standard, high power, and plasma emulation – or with a quartz-tungsten halogen XL 3000 (3M ESPE) in conventional mode. All modes were set to deliver 19 J/cm2. The DC (N = 20) was determined by Fourier transform infrared spectrometry on the top (T) and bottom (B) surfaces. For the KHN test, samples were subdivided in four groups (n = 5 each) according to the storage media: absolute ethanol, 75% ethanol, distilled water, and air (control group). The KHN values were evaluated on T and B before and 24 h after immersion in the storage media. Data were analyzed by split-plot analysis of variance (ANOVA; for DC) or repeated-measures split-plot ANOVA (for KHN), followed by Tukey's test (? = 0.05). Results: For the DC, the light-activation protocol did not influence the results and there was no difference between T and B. For the KHN test, the light-activation protocol did not influence the results and T showed higher microhardness values than B for all experimental conditions. There were significant differences in KHN depending on the storage media. Samples immersed in absolute ethanol generally presented lower KHN values, with no differences compared to samples in 75% ethanol. Conclusion: The storage media affected the outcomes of the softening test. PMID:24966740

Giorgi, Maria Cecília Caldas; Lima, Débora Alves Nunes Leite; Marchi, Giselle Maria; Ambrosano, Gláucia Maria; Aguiar, Flávio Henrique Baggio

2014-01-01

246

14 CFR 25.535 - Auxiliary float loads.  

Code of Federal Regulations, 2014 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2014-01-01

247

14 CFR 25.535 - Auxiliary float loads.  

Code of Federal Regulations, 2012 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2012-01-01

248

14 CFR 23.535 - Auxiliary float loads.  

Code of Federal Regulations, 2014 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2014-01-01

249

14 CFR 23.535 - Auxiliary float loads.  

Code of Federal Regulations, 2012 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2012-01-01

250

14 CFR 23.535 - Auxiliary float loads.  

Code of Federal Regulations, 2013 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2013-01-01

251

14 CFR 25.535 - Auxiliary float loads.  

Code of Federal Regulations, 2013 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2013-01-01

252

14 CFR 25.535 - Auxiliary float loads.  

Code of Federal Regulations, 2011 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2011-01-01

253

14 CFR 23.535 - Auxiliary float loads.  

Code of Federal Regulations, 2011 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2011-01-01

254

Free-floating planets from microlensing  

NASA Astrophysics Data System (ADS)

Gravitational microlensing has an unique sensitivity to exoplanets at outside of the snow-line and even exoplanets unbound to any host stars because the technique does not rely on any light from the host but the gravity of the lens. MOA and OGLE collaborations reported the discovery of a population of unbound or distant Jupiter-mass objects, which are almost twice (1.8_{-0.8}^{+1.7}) as common as main-sequence stars, based on two years of gravitational microlensing survey observations toward the Galactic Bulge. These planetary-mass objects have no host stars that can be detected within about ten astronomical units by gravitational microlensing. However a comparison with constraints from direct imaging suggests that most of these planetary-mass objects are not bound to any host star. The such short-timescale unbound planetary candidates have been detected with the similar rate in on-going observations and these groups are working to update the analysis with larger statistics. Recently, there are also discoveries of free-floating planetary mass objects by the direct imaging in young star-forming regions and in the moving groups, but these objects are limited to massive objects of 3 to 15 Jupiter masses.They are more massive than the population found by microlensing. So they may be a different population with the different formation process, either similar with that of stars and brown dwarfs, or formed in proto-planetary disks and subsequently scattered into unbound or very distant orbits. It is important to fill the gap of these mass ranges to fully understand these populations. The Wide Field Infrared Survey Telescope (WFIRST) is the highest ranked recommendation for a large space mission in the recent New Worlds, New Horizons (NWNH) in Astronomy and Astrophysics 2010 Decadal Survey. Exoplanet microlensing program is one of the primary science of WFIRST. WFIRST will find about 3000 bound planets and 2000 unbound planets by the high precision continuous survey 15 min. cadence. WFIRST can complete the statistical census of planetary systems in the Galaxy, from super-Earths beyond the snow-line to gravitationally unbound planets - a discovery space inaccessible to other exoplanet detection techniques.

Sumi, Takahiro

2014-06-01

255

Submerged floating tunnels (SFTs) for Norwegian fjords  

Microsoft Academic Search

Submerged floating tunnels (SFTs) weigh roughly the same as the surrounding water. The loads on the tunnel depend on the variation of the forces on the tunnel. The forces come from variation in traffic, current, temperature, waves, weight of water, weight of concrete, growth on the tunnel, wear of asphalt, dust and debris, relaxation of prestress and shrinkage and creep

Per Tveit

2010-01-01

256

Floating hydrometer with energy dissipating baffle  

Microsoft Academic Search

This patent describes a floating hydrometer employable for purposes of obtaining measurements of the presence of suspended solids in a fluid substance contained in a receptacle comprising: a. a probe portion operative as an instrument-bearing housing; b. an elongated tubular element having a hollow interior and at least one open end so as to enable the flow into the hollow

Kownurko

1987-01-01

257

Daphnia (zoomed on floating blood cells)  

NSDL National Science Digital Library

These pin drops are the clearly defined blood cells of the Daphnia. We are only able to see the cells with use of a microscope. Keep in mind that the cells are not confined in any blood vessel (called an open circulatory system) and freely float throughout the body.

Katie Hale (CSUF; Biological Sciences)

2007-07-18

258

Dealing with Human Death: The Floating Perspective.  

ERIC Educational Resources Information Center

Explores approach to dealing with human death. Describes floating perspective, based on insights from Choron and Jaspers, as suggesting it is possible to deal with human death by refraining from taking ultimate position on the problem. Position encourages openness to death. Examines role of anxiety and describes possible meaningful outcomes of…

Kenyon, Gary M.

1991-01-01

259

Mass spectrometry footprinting reveals the structural rearrangements of cyanobacterial orange carotenoid protein upon light activation.  

PubMed

The orange carotenoid protein (OCP), a member of the family of blue light photoactive proteins, is required for efficient photoprotection in many cyanobacteria. Photoexcitation of the carotenoid in the OCP results in structural changes within the chromophore and the protein to give an active red form of OCP that is required for phycobilisome binding and consequent fluorescence quenching. We characterized the light-dependent structural changes by mass spectrometry-based carboxyl footprinting and found that an ? helix in the N-terminal extension of OCP plays a key role in this photoactivation process. Although this helix is located on and associates with the outside of the ?-sheet core in the C-terminal domain of OCP in the dark, photoinduced changes in the domain structure disrupt this interaction. We propose that this mechanism couples light-dependent carotenoid conformational changes to global protein conformational dynamics in favor of functional phycobilisome binding, and is an essential part of the OCP photocycle. PMID:25256653

Liu, Haijun; Zhang, Hao; King, Jeremy D; Wolf, Nathan R; Prado, Mindy; Gross, Michael L; Blankenship, Robert E

2014-09-22

260

Structure-Guided Transformation of Channelrhodopsin into a Light-Activated Chloride Channel  

PubMed Central

Using light to silence electrical activity in targeted cells is a major goal of optogenetics. Available optogenetic proteins that directly move ions to achieve silencing are inefficient, pumping only a single ion per photon across the cell membrane rather than allowing many ions per photon to flow through a channel pore. Building on high-resolution crystal-structure analysis, pore vestibule modeling, and structure-guided protein engineering, we designed and characterized a class of channelrhodopsins (originally cation-conducting) converted into chloride-conducting anion channels. These tools enable fast optical inhibition of action potentials and can be engineered to display step-function kinetics for stable inhibition, outlasting light pulses and for orders-of-magnitude-greater light sensitivity of inhibited cells. The resulting family of proteins defines an approach to more physiological, efficient, and sensitive optogenetic inhibition. PMID:24763591

Berndt, Andre; Lee, Soo Yeun; Ramakrishnan, Charu; Deisseroth, Karl

2014-01-01

261

Biomechanical model produced from light-activated dental composite resins: a holographic analysis  

NASA Astrophysics Data System (ADS)

Light-activated dental composites, commonly applied in dentistry, can be used as excellent material for producing biomechanical models. They can be cast in almost any shape in an appropriate silicone mold and quickly solidified by irradiation with light in the blue part of the spectrum. In that way, it is possible to obtain any number of nearly identical casts. The models can be used to study the behavior of arbitrary structure under mechanical loads. To test the technique, a simple mechanical model of the tooth with a mesio-occluso-distal cavity was manufactured. Composite resin restoration was placed inside the cavity and light cured. Real-time holographic interferometry was used to analyze the contraction of the composite resin and its effect on the surrounding material. The results obtained in the holographic experiment were in good agreement with those obtained using the finite element method.

Panteli?, Dejan; Vasiljevi?, Darko; Blaži?, Larisa; Savi?-Ševi?, Svetlana; Muri?, Branka; Nikoli?, Marko

2013-11-01

262

Engineering Escherichia coli for Light-Activated Cytolysis of Mammalian Cells.  

PubMed

By delivering payloads in response to specific exogenous stimuli, smart bacterial therapeutics have the potential to overcome many limitations of conventional therapies, including poor targeting specificity and dosage control in current cancer treatments. Although not yet explored as a trigger for bacterial drug delivery, light is an ideal induction mechanism because it offers fine spatiotemporal control and is easily and safely administered. Using recent advances in optogenetics, we have engineered two strains of Escherichia coli to secrete a potent mammalian cytotoxin in response to blue or red light. The tools in this study demonstrate the initial feasibility of light-activated bacterial therapeutics for applications such as tumor cytolysis, and their modular nature should enable simple substitution of other payloads of interest. PMID:24933444

Magaraci, Michael S; Veerakumar, Avin; Qiao, Peter; Amurthur, Ashwin; Lee, Justin Y; Miller, Jordan S; Goulian, Mark; Sarkar, Casim A

2014-12-19

263

AgVO3 nanorods: Synthesis, characterization and visible light photocatalytic activity  

NASA Astrophysics Data System (ADS)

Large scale and high purity silver vanadate (AgVO3) nanorods were synthesized by thermal decomposition method. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, Ultraviolet-Visible (DRS-UV-Visible) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to characterize the structure, light absorption capacity and morphology of the as-synthesized sample. The photocatalytic activity of AgVO3 nanorods was examined by degradation of methylene blue (MB) as a model organic pollutant. The degradation efficiency is 85.02% in the 120 min visible light illumination. Further, the AgVO3 nanorods were used as a photocatalyst for industrial effluent. 95.4% degradation efficiency was obtained within the visible light irradiation of 120 min. The possible photocatalytic mechanism has also been proposed.

Sivakumar, V.; Suresh, R.; Giribabu, K.; Narayanan, V.

2015-01-01

264

Photoactive titania float for disinfection of water; evaluation of cell damage by bioanalytical techniques.  

PubMed

A photoactive float was fabricated with the modified titania to cause a feasible disinfection of water, contaminated with E. coli. The commercially available titania was doped with neodymium by pulverization technique to enhance its activity in sunlight and a multiapproach technique was used to evaluate the extended efficiency of the doped sample. X-ray diffraction patterns depicted the retention of anatase phase on doping and the existence of neodymium was confirmed by the energy dispersive atomic X-ray analysis and the X-ray photoelectron spectroscopy. Transmission electron microscopy and Bruner-Emmett-Teller analysis depicted a marginal increase in the particle size and a decrease in the surface area, respectively. Doping induces semiconductor behavior with lower band energy that could respond to visible light and exhibit better disinfection activity. The "f" and "d" transitions of the lanthanide in doped sample caused new electronic behavior of trapping/detrapping effect together with bandgap narrowing. The amount of malondialdehyde, protein, DNA and RNA released on destruction of E. coli was observed to be 0.915 × 10(-3) ?g mL(-1), 859.912 ?g mL(-1), 20.173 ?g mL(-1) and 1146.073 ?g mL(-1), respectively. The above analytical methods along with standard plate count method substantiated the enhanced disinfection efficiency of the doped sample in sunlight. PMID:24689654

Shwetharani, R; Jyothi, M S; Laveena, P D; Geetha Balakrishna, R

2014-01-01

265

A spinal opsin controls early neural activity and drives a behavioral light response.  

PubMed

Nonvisual detection of light by the vertebrate hypothalamus, pineal, and retina is known to govern seasonal and circadian behaviors [1]. However, the expression of opsins in multiple other brain structures [2-4] suggests a more expansive repertoire for light regulation of physiology, behavior, and development. Translucent zebrafish embryos express extraretinal opsins early on [5, 6], at a time when spontaneous activity in the developing CNS plays a role in neuronal maturation and circuit formation [7]. Though the presence of extraretinal opsins is well documented, the function of direct photoreception by the CNS remains largely unknown. Here, we show that early activity in the zebrafish spinal central pattern generator (CPG) and the earliest locomotory behavior are dramatically inhibited by physiological levels of environmental light. We find that the photosensitivity of this circuit is conferred by vertebrate ancient long opsin A (VALopA), which we show to be a G?i-coupled receptor that is expressed in the neurons of the spinal network. Sustained photoactivation of VALopA not only suppresses spontaneous activity but also alters the maturation of time-locked correlated network patterns. These results uncover a novel role for nonvisual opsins and a mechanism for environmental regulation of spontaneous motor behavior and neural activity in a circuit previously thought to be governed only by intrinsic developmental programs. PMID:25484291

Friedmann, Drew; Hoagland, Adam; Berlin, Shai; Isacoff, Ehud Y

2015-01-01

266

Light-activated hydrolysis of GTP and cyclic GMP in the rod outer segments.  

PubMed Central

1. The hydrolysis of guanosine triphosphate (GTP) and the consequent formation of guanosine diphosphate (GDP) and phosphate (P1) are activated by light in a suspension of broken retinal rods: the hydrolysis rate with GTP in the micrometer concentration range is 2.5-3.5 n-mole/min per mg of rhodopsin in the preparation. 2. The ionic composition of the medium suspending the rods is not critical: the hydrolysis is present in NaCl saline solution with MG2+ as well as in Tris-HC1 buffer solution, and with the chelating agent EDTA. 3. The ionic strength is critical: the effect is reduced when the broken rods are suspended in a low salt mannitol solution, and is altogether abolished when they are separated from the mannitol solution; it reappears when the mannitol solution is added again in the presence of salts. An element essential for the effect is thus reversibly released in the mannitol solution. No hydrolytic activity on GTP, however, is found in the mannitol soluble fraction. 4. The cyclic nucleotide phosphodiesterase is eluted from the rods in the mannitol solution, and is reaggregated to the rods in the presence of salts; once recombined with the rods, it can be activated by light. 5. The activation of the phosphodiesterase by light is present in the absence of added nucleotide triphosphates. PMID:209180

Bignetti, E; Cavaggioni, A; Sorbi, R T

1978-01-01

267

Light-activated hydrolysis of GTP and cyclic GMP in the rod outer segments.  

PubMed

1. The hydrolysis of guanosine triphosphate (GTP) and the consequent formation of guanosine diphosphate (GDP) and phosphate (P1) are activated by light in a suspension of broken retinal rods: the hydrolysis rate with GTP in the micrometer concentration range is 2.5-3.5 n-mole/min per mg of rhodopsin in the preparation. 2. The ionic composition of the medium suspending the rods is not critical: the hydrolysis is present in NaCl saline solution with MG2+ as well as in Tris-HC1 buffer solution, and with the chelating agent EDTA. 3. The ionic strength is critical: the effect is reduced when the broken rods are suspended in a low salt mannitol solution, and is altogether abolished when they are separated from the mannitol solution; it reappears when the mannitol solution is added again in the presence of salts. An element essential for the effect is thus reversibly released in the mannitol solution. No hydrolytic activity on GTP, however, is found in the mannitol soluble fraction. 4. The cyclic nucleotide phosphodiesterase is eluted from the rods in the mannitol solution, and is reaggregated to the rods in the presence of salts; once recombined with the rods, it can be activated by light. 5. The activation of the phosphodiesterase by light is present in the absence of added nucleotide triphosphates. PMID:209180

Bignetti, E; Cavaggioni, A; Sorbi, R T

1978-06-01

268

DISTINCT PATTERNS OF NITRATE REDUCTASE ACTIVITY IN BROWN ALGAE: LIGHT AND AMMONIUM SENSITIVITY IN LAMINARIA DIGITATA IS ABSENT IN  

E-print Network

DISTINCT PATTERNS OF NITRATE REDUCTASE ACTIVITY IN BROWN ALGAE: LIGHT AND AMMONIUM SENSITIVITY and lowest in summer. This is the first report of NR activity in any alga that is not strongly regulated the regulation of NR by light that has been observed in other algae and higher plants. Key index words: ammonium

Berges, John A.

269

Dye Surface Coating Enables Visible Light Activation of TiO2 Nanoparticles Leading to Degradation of  

E-print Network

Dye Surface Coating Enables Visible Light Activation of TiO2 Nanoparticles Leading to Degradation that an alizarin red S ~ARS! dye coating on TiO2 nanoparticles enables visible light activation of reactive oxygen species. Successful coating of nanoparti- cles with dye is demonstrated through

Brown, Eric

270

Development of White-Light Emitting Active Layers in Nitride Based Heterostructures for Phosphorless Solid State Lighting  

SciTech Connect

This report provides a summary of research activities carried out at the University of California, San Diego and Central Research of OSRAM SYLVANIA in Beverly, MA partially supported by a research contract from US Department of Energy, DE-FC26-04NT422274. The main objective of this project was to develop III-V nitrides activated by rare earth ions, RE{sup 3+}, which could eliminate the need for phosphors in nitride-based solid state light sources. The main idea was to convert electron-hole pairs injected into the active layer in a LED die to white light directly through transitions within the energy levels of the 4f{sup n}-manifold of RE{sup 3+}. We focused on the following materials: Eu{sup 3+}(red), Tb{sup 3+}(green), Er{sup 3+}(green), Dy{sup 3+}(yellow) and Tm{sup 3+}(blue) in AlN, GaN and alloys of AlN and GaN. Our strategy was to explore candidate materials in powder form first, and then study their behavior in thin films. Thin films of these materials were to be deposited on sapphire substrates using pulsed laser deposition (PLD) and metal organic vapor phase epitaxy (MOVPE). The photo- and cathode-luminescence measurements of these materials were used to investigate their suitability for white light generation. The project proceeded along this route with minor modifications needed to produce better materials and to expedite our progress towards the final goal. The project made the following accomplishments: (1) red emission from Eu{sup 3+}, green from Tb{sup 3+}, yellow from Dy{sup 3+} and blue from Tm{sup 3+} in AlN powders; (2) red emission from Eu{sup 3+} and green emission from Tb{sup 3+} in GaN powder; (3) red emission from Eu{sup 3+} in alloys of GaN and AlN; (4) green emission from Tb{sup 3+} in GaN thin films by PLD; (5) red emission from Eu{sup 3+} and Tb{sup 3+} in GaN thin films deposited by MOVPE; (6) energy transfer from host to RE{sup 3+}; (7) energy transfer from Tb{sup 3+} to Eu{sup 3+} in AlN powders; (8) emission from AlN powder samples codoped with (Eu{sup 3+} ,Tb{sup 3+} ) and (Dy{sup 3+}, Tm{sup 3+}); and (9) white emission from AlN codoped with Dy{sup 3+} and Tm{sup 3+}. We also extensively studied the stabilities of rare earth ions in GaN, and the nature of oxygen defects in GaN and its impact on the optical properties of the host material, using first principles method. Results from these theoretical calculations together with fluorescence measurements from the materials essentially proved the underlying concepts for generating white light using RE{sup 3+}-activated nitrides. For this project, we successfully built a horizontal MOVPE reactor and used it to deposit thin films of undoped and doped nitrides of GaN and InGaN, which is a very significant achievement. Since this reactor was designed and built by in-house experts, it could be easily modified and reassembled for specific research purposes. During this study, it was successfully modified for homogeneous distribution of rare earth ions in a deposited film. It will be an ideal tool for future research involving novel thin film material concepts. We examined carefully the suitability of various metal organic precursors for incorporating RE{sup 3+}. In order to avoid oxygen contamination, several oxygen-free RE{sup 3+} precursors were identified. Both oxygen-free and oxygen- containing metal organic precursors were used for certain rare earth ions (Eu{sup 3+}, Tb{sup 3+} and Er{sup 3+}). However, the suitability of any particular type of precursor for MOVPE deposition was not established during this study, and further study is needed. More intensive research in the future is needed to improve the film quality, and eliminate the separation of rare earth oxide phases during the deposition of thin films by MOVPE. The literature in the area of the chemistry of rare earth ions in nitrides is almost nonexistent, in spite of the significant research on luminescence of RE{sup 3+} in nitrides. Consequently, MOVPE as a method of deposition of RE{sup 3+}-activated nitrides is relatively unexplored. In the following sections of this report, the ou

Jan Talbot; Kailash Mishra

2007-12-31

271

Blue-light-activated phototropin2 trafficking from the cytoplasm to Golgi/post-Golgi vesicles  

PubMed Central

Phototropins are plasma membrane-localized UVA/blue light photoreceptors which mediate phototropism, inhibition of primary hypocotyl elongation, leaf positioning, chloroplast movements, and stomatal opening. Blue light irradiation activates the C-terminal serine/threonine kinase domain of phototropin which autophosphorylates the receptor. Arabidopsis thaliana encodes two phototropins, phot1 and phot2. In response to blue light, phot1 moves from the plasma membrane into the cytosol and phot2 translocates to the Golgi complex. In this study the molecular mechanism and route of blue-light-induced phot2 trafficking are demonstrated. It is shown that Atphot2 behaves in a similar manner when expressed transiently under 35S or its native promoter. The phot2 kinase domain but not blue-light-mediated autophosphorylation is required for the receptor translocation. Using co-localization and western blotting, the receptor was shown to move from the cytoplasm to the Golgi complex, and then to the post-Golgi structures. The results were confirmed by brefeldin A (an inhibitor of the secretory pathway) which disrupted phot2 trafficking. An association was observed between phot2 and the light chain2 of clathrin via bimolecular fluorescence complementation. The fluorescence was observed at the plasma membrane. The results were confirmed using co-immunoprecipitation. However, tyrphostin23 (an inhibitor of clathrin-mediated endocytosis) and wortmannin (a suppressor of receptor endocytosis) were not able to block phot2 trafficking, indicating no involvement of receptor endocytosis in the formation of phot2 punctuate structures. Protein turnover studies indicated that the receptor was continuously degraded in both darkness and blue light. The degradation of phot2 proceeded via a transport route different from translocation to the Golgi complex. PMID:24821953

Aggarwal, Chhavi; Bana?, Agnieszka Katarzyna; Kasprowicz-Malu?ki, Anna; Borghetti, Carolina; ?abuz, Justyna; Dobrucki, Jerzy; Gabry?, Halina

2014-01-01

272

Active-region Tilt Angles: Magnetic versus White-light Determinations of Joy's Law  

NASA Astrophysics Data System (ADS)

The axes of solar active regions are inclined relative to the east-west direction, with the tilt angle tending to increase with latitude ("Joy's law"). Observational determinations of Joy's law have been based either on white-light images of sunspot groups or on magnetograms, where the latter have the advantage of measuring directly the physically relevant quantity (the photospheric field), but the disadvantage of having been recorded routinely only since the mid-1960s. White-light studies employing the historical Mount Wilson (MW) database have yielded tilt angles that are smaller and that increase less steeply with latitude than those obtained from magnetic data. We confirm this effect by comparing sunspot-group tilt angles from the Debrecen Photoheliographic Database with measurements made by Li and Ulrich using MW magnetograms taken during cycles 21-23. Whether white-light or magnetic data are employed, the median tilt angles significantly exceed the mean values, and provide a better characterization of the observed distributions. The discrepancy between the white-light and magnetic results is found to have two main sources. First, a substantial fraction of the white-light "tilt angles" refer to sunspots of the same polarity. Of greater physical significance is that the magnetograph measurements include the contribution of plage areas, which are invisible in white-light images but tend to have greater axial inclinations than the adjacent sunspots. Given the large uncertainties inherent in both the white-light and the magnetic measurements, it remains unclear whether any systematic relationship exists between tilt angle and cycle amplitude during cycles 16-23.

Wang, Y.-M.; Colaninno, R. C.; Baranyi, T.; Li, J.

2015-01-01

273

Real-time RMS active damping augmentation: Heavy and very light payload evaluations  

NASA Technical Reports Server (NTRS)

Controls-Structures Integration Technology has been applied to the Space Shuttle Remote Manipulator System (RMS) to improve on-orbit performance. The objective was to actively damp undesired oscillatory motions of the RMS following routine payload maneuvering and Shuttle attitude control thruster firings. Simulation of active damping was conducted in the real-time, man-in-the-loop Systems Engineering Simulator at NASA's Johnson Space Center. The simulator was used to obtain qualitative and quantitative data on active damping performance from astronaut operators. Using a simulated three-axis accelerometer mounted on the RMS, 'sensed' vibration motions were used to generate joint motor commands that reduced the unwanted oscillations. Active damping of the RMS with heavy and light attached payloads was demonstrated in this study. Five astronaut operators examined the performance of active damping following operator commanded RMS maneuvers and Shuttle thruster firings. Noticeable improvements in the damping response of the RMS with the heavy, Hubble Space Telescope payload and the very light, astronaut in Manipulator Foot Restraint payload were observed. The potential of active damping to aid in precisely maneuvering payloads was deemed significant.

Demeo, Martha E.; Gilbert, Michael G.; Lepanto, Janet A.; Flueckiger, Karl W.; Bains, Elizabeth M.; Jensen, Mary C.

1994-01-01

274

Converting visible light into UVC: microbial inactivation by Pr(3+)-activated upconversion materials.  

PubMed

Herein we report the synthesis and properties of light-activated antimicrobial surfaces composed of lanthanide-doped upconversion luminescent nano- and microcrystalline Y(2)SiO(5). Unlike photocatalytic surfaces, which convert light energy into reactive chemical species, this work describes surfaces that inactivate microorganisms through purely optical mechanisms, wherein incident visible light is partially converted into germicidal UVC radiation. Upconversion phosphors utilizing a Pr(3+) activator ion were synthesized and their visible-to-ultraviolet conversion capabilities were confirmed via photoluminescence spectroscopy. Polycrystalline films were prepared on glass substrates, and the extent of surface microbial inactivation and biofilm inhibition under visible light excitation were investigated. Results show that, under normal visible fluorescent lamp exposure, a sufficient amount of UVC radiation was emitted to inhibit Pseudomonas aeruginosa biofilm formation and to inactivate Bacillus subtilis spores on the dry surfaces. This new application of upconversion luminescence shows for the first time its ability to deter microbial contamination and could potentially lead to new material strategies for disinfection of surfaces and water. PMID:21428395

Cates, Ezra L; Cho, Min; Kim, Jae-Hong

2011-04-15

275

On the origin of visible light activity in carbon-modified titania.  

PubMed

Characterization of a commercial carbon-modified titania visible light photocatalyst (VLP) reveals a quasi-Fermi level of -0.50 V at pH 7 and characteristic C1s binding energies of 284.8 eV and 286.3 eV as measured by XPS. Treatment with sodium hydroxide affords a soluble brown extract SENSex exhibiting in the IR spectrum intense peaks at 1420 cm(-1) and 1580 cm(-1), tentatively assigned to an arylcarboxylate group. Both the residue and the solution SENSex do not induce significant visible light mineralization of 4-chlorophenol. However, after heating them together in suspension, followed by calcination at 200 degrees C the resulting powder VLPreas exhibits the same quasi-Fermi level and C1s binding energies as the original VLP. Furthermore, within experimental error its visible light activity is identical with that of VLP. These results clearly indicate that, at least for VLP but probably also for other "carbon-doped" titania materials, an aromatic carbon compound and not substitutional or interstitial carbon is the origin of visible light activity. PMID:19247520

Zabek, Przemys?aw; Eberl, Joachim; Kisch, Horst

2009-02-01

276

Redox and Light Control the Heme-Sensing Activity of AppA  

PubMed Central

ABSTRACT The DNA binding activity of the photosystem-specific repressor PpsR is known to be repressed by the antirepressor AppA. AppA contains a blue-light-absorbing BLUF domain and a heme-binding SCHIC domain that controls the interaction of AppA with PpsR in response to light and heme availability. In this study, we have solved the structure of the SCHIC domain and identified the histidine residue that is critical for heme binding. We also demonstrate that dark-adapted AppA binds heme better than light-excited AppA does and that heme bound to the SCHIC domain significantly reduces the length of the BLUF photocycle. We further show that heme binding to the SCHIC domain is affected by the redox state of a disulfide bridge located in the Cys-rich carboxyl-terminal region. These results demonstrate that light, redox, and heme are integrated inputs that control AppA’s ability to disrupt the DNA binding activity of PpsR. PMID:23982072

Yin, Liang; Dragnea, Vladimira; Feldman, George; Hammad, Loubna A.; Karty, Jonathan A.; Dann, Charles E.; Bauer, Carl E.

2013-01-01

277

Superhydrophilicity-assisted preparation of transparent and visible light activated N-doped titania film  

NASA Astrophysics Data System (ADS)

A novel and environmental friendly method was developed to prepare transparent, uniform, crack-free and visible light activated nitrogen doped (N-doped) titania thin films without the use of organic Ti precursors and organic solvents. The N-doped titania films were prepared from heating aqueous peroxotitanate thin films deposited uniformly on superhydrophilic uncoated glass substrates. The pure glass substrates were superhydrophilic after being heated at 500 °C for 1 h. Nitrogen concentrations in the titania films were adjusted by changing the amount of ammonia solution. The optimal photocatalytic activity of the N-doped titania films was about 14 times higher than that of a commercial self-cleaning glass under the same visible light illumination. The current reported preparative technique is generally applicable for the preparation of other thin films.

Xu, Qing Chi; Wellia, Diana V.; Amal, Rose; Liao, Dai Wei; Loo, Say Chye Joachim; Tan, Timothy Thatt Yang

2010-07-01

278

Superhydrophilicity-assisted preparation of transparent and visible light activated N-doped titania film.  

PubMed

A novel and environmental friendly method was developed to prepare transparent, uniform, crack-free and visible light activated nitrogen doped (N-doped) titania thin films without the use of organic Ti precursors and organic solvents. The N-doped titania films were prepared from heating aqueous peroxotitanate thin films deposited uniformly on superhydrophilic uncoated glass substrates. The pure glass substrates were superhydrophilic after being heated at 500 degrees C for 1 h. Nitrogen concentrations in the titania films were adjusted by changing the amount of ammonia solution. The optimal photocatalytic activity of the N-doped titania films was about 14 times higher than that of a commercial self-cleaning glass under the same visible light illumination. The current reported preparative technique is generally applicable for the preparation of other thin films. PMID:20648337

Xu, Qing Chi; Wellia, Diana V; Amal, Rose; Liao, Dai Wei; Loo, Say Chye Joachim; Tan, Timothy Thatt Yang

2010-07-01

279

Teaching Strategies and Conceptual Change: Sinking and Floating at Elementary School Level.  

ERIC Educational Resources Information Center

This paper describes the design and results of a study carried out with elementary pupils ages 8-9 years on the topic of sinking and floating, with the aim of checking the validity of a general scheme for classroom activities based on a constructivist perspective. Children's "ways of looking" at buoyancy and the production of materials that could…

Tomasini, N. Grimellini; And Others

280

Effect of light on the activity of motor cortex neurons during locomotion  

PubMed Central

The motor cortex plays a critical role in accurate visually guided movements such as reaching and target stepping. However, the manner in which vision influences the movement-related activity of neurons in the motor cortex is not well understood. In this study we have investigated how the locomotion-related activity of neurons in the motor cortex is modified when subjects switch between walking in the darkness and in light. Three adult cats were trained to walk through corridors of an experimental chamber for a food reward. On randomly selected trials, lights were extinguished for approximately four seconds when the cat was in a straight portion of the chamber's corridor. Discharges of 146 neurons from layer V of the motor cortex, including 51 pyramidal tract cells (PTNs), were recorded and compared between light and dark conditions. It was found that while cats’ movements during locomotion in light and darkness were similar (as judged from the analysis of three-dimensional limb kinematics and the activity of limb muscles), the firing behavior of 49% (71/146) of neurons was different between the two walking conditions. This included differences in the mean discharge rate (19%, 28/146 of neurons), depth of stride-related frequency modulation (24%, 32/131), duration of the period of elevated firing ([PEF], 19%, 25/131), and number of PEFs among stride-related neurons (26%, 34/131). 20% of responding neurons exhibited more than one type of change. We conclude that visual input plays a very significant role in determining neuronal activity in the motor cortex during locomotion by altering one, or occasionally multiple, parameters of locomotion-related discharges of its neurons. PMID:23680161

Armer, Madison C.; Nilaweera, Wijitha U.; Rivers, Trevor J.; Dasgupta, Namrata M.; Beloozerova, Irina N.

2013-01-01

281

Millisecond time scale atmospheric light pulses associated with solar and magnetospheric activity.  

NASA Technical Reports Server (NTRS)

By using a wide-angle photomultiplier system a class of millisecond time scale diffuse atmospheric light emission of terrestrial origin has been discovered. These fast atmospheric pulsation events also show damped oscillations around 10-kHz frequency, which distinguishes them from ordinary lightning-type events. Evidence is presented for the enhancement in the rate of these events induced by solar flare activity.

Ogelman, H.

1973-01-01

282

The Stellar Activity of an M Dwarf Binary from Deconvolved Kepler Light Curves  

NASA Astrophysics Data System (ADS)

The M5+M5 pair GJ 1245AB was monitored almost continuously by Kepler for four years, providing a unique opportunity to study the stellar activity of two coeval, nearly-equal mass M dwarfs that are fully convective. The stars are 7" apart on the sky, and separate light curves for each star cannot be generated via aperture photometry due to Kepler's large 4"/pixel plate scale. Instead, we generated separate light curves from the target pixel files using the PyKE pixel response function modeling procedures. Intriguingly, the angular separation of the two stars decreases over the four years of Kepler observations in a manner consistent with an astrometric perturbation from the much fainter, unseen M8 (GJ 1245C) companion to GJ 1245A. Analyzing the separated light curves, we observe long lived starspot features on both stars that evolve on multi-year timescales. Both stars flare at nearly the same rate, despite having rotation rates that differ by almost a factor of three. Consistent with recent studies of active M dwarf binaries, these results provide further insight into the roles of age and rotation rate in stellar activity.

Lurie, John C.; Davenport, James R. A.; Hawley, Suzanne L.; Wilkinson, Tessa D.

2015-01-01

283

Light Activation of the Insulin Receptor Regulates Mitochondrial Hexokinase. A Possible Mechanism of Retinal Neuroprotection  

PubMed Central

The serine/threonine kinase Akt has been shown to mediate the anti-apoptotic activity through hexokinase (HK)-mitochondria interaction. We previously reported that Akt activation in retinal rod photoreceptor cells is mediated through light-dependent insulin receptor (IR)/PI3K pathway. Our data indicate that light-induced activation of IR/PI3K/Akt results in the translocation of HK-II to mitochondria. We also found that PHLPPL, a serine/threonine phosphatase, enhanced the binding of HK-II to mitochondria. We found a mitochondrial targeting signal in PHLPPL and our study suggests that Akt translocation to mitochondria could be mediated through PHLPPL. Our results suggest that light-dependent IR/PI3K/Akt pathway regulates hexokinase-mitochondria interaction in photoreceptors. Down-regulation of IR signaling has been associated with ocular diseases of retinitis pigmentosa, diabetic retinopathy, and Leber Congenital Amaurosis-type 2, and agents that enhance the binding interaction between hexokinase and mitochondria may have therapeutic potential against these ocular diseases. PMID:23993956

Rajala, Ammaji; Gupta, Vivek K.; Anderson, Robert E.; Rajala, Raju V.S.

2013-01-01

284

Synthesis and photocatalytic activity of perovskite niobium oxynitrides with wide visible-light absorption bands.  

PubMed

Photocatalytic activities of perovskite-type niobium oxynitrides (CaNbO?N, SrNbO?N, BaNbO?N, and LaNbON?) were examined for hydrogen and oxygen evolution from water under visible-light irradiation. These niobium oxynitrides were prepared by heating the corresponding oxide precursors, which were synthesized using the polymerized complex method, for 15?h under a flow of ammonia. They possess visible-light absorption bands between 600-750?nm, depending on the A-site cations in the structures. The oxynitride CaNbO?N, was found to be active for hydrogen and oxygen evolution from methanol and aqueous AgNO?, respectively, even under irradiation by light at long wavelengths (?<560?nm). The nitridation temperature dependence of CaNbO?N was investigated and 1023?K was found to be the optimal temperature. At lower temperatures, the oxynitride phase is not adequately produced, whereas higher temperatures produce more reduced niobium species (e. g., Nb³(+) and Nb?(+)), which can act as electron-hole recombination centers, resulting in a decrease in activity. PMID:21226214

Siritanaratkul, Bhavin; Maeda, Kazuhiko; Hisatomi, Takashi; Domen, Kazunari

2011-01-17

285

Simultaneous whole-animal 3D-imaging of neuronal activity using light field microscopy  

E-print Network

3D functional imaging of neuronal activity in entire organisms at single cell level and physiologically relevant time scales faces major obstacles due to trade-offs between the size of the imaged volumes, and spatial and temporal resolution. Here, using light-field microscopy in combination with 3D deconvolution, we demonstrate intrinsically simultaneous volumetric functional imaging of neuronal population activity at single neuron resolution for an entire organism, the nematode Caenorhabditis elegans. The simplicity of our technique and possibility of the integration into epi-fluoresence microscopes makes it an attractive tool for high-speed volumetric calcium imaging.

Prevedel, R; Hoffmann, M; Pak, N; Wetzstein, G; Kato, S; Schrödel, T; Raskar, R; Zimmer, M; Boyden, E S; Vaziri, A

2014-01-01

286

Increased antioxidant activity and changes in phenolic profile of Kalanchoe pinnata (Lamarck) Persoon (Crassulaceae) specimens grown under supplemental blue light.  

PubMed

Antioxidant compounds protect plants against oxidative stress caused by environmental conditions. Different light qualities, such as UV-A radiation and blue light, have shown positive effects on the production of phenols in plants. Kalanchoe pinnata (Lamarck) Persoon (Crassulaceae) is used for treating wounds and inflammations. Some of these beneficial effects are attributed to the antioxidant activity of plant components. We investigated the effects of blue light and UV-A radiation supplementation on the total phenol content, antioxidant activity and chromatographic profile of aqueous extracts from leaves of K. pinnata. Monoclonal plants were grown under white light, white plus blue light and white plus UV-A radiation. Supplemental blue light improved the antioxidant activity and changed the phenolic profile of the extracts. Analysis by HPLC of supplemental blue-light plant extracts revealed a higher proportion of the major flavonoid quercetin 3-O-?-L-arabinopyranosyl (1?2) ?-L-rhamnopyranoside, as well as the presence of a wide variety of other phenolic substances. These findings may explain the higher antioxidant activity observed for this extract. Blue light is proposed as a supplemental light source in the cultivation of K. pinnata, to improve its antioxidant activity. PMID:23057576

Nascimento, Luana B S; Leal-Costa, Marcos V; Coutinho, Marcela A S; Moreira, Nattacha dos S; Lage, Celso L S; Barbi, Nancy dos S; Costa, Sônia S; Tavares, Eliana S

2013-01-01

287

Microwave hydrothermal synthesis of AgInS{sub 2} with visible light photocatalytic activity  

SciTech Connect

Highlights: {yields} AgInS{sub 2} nanoparticles were synthesized by a microwave hydrothermal method. {yields} This method involves no organic solvents, catalysts, or surfactants. {yields} AgInS{sub 2} showed higher activity for photocatalytic degradation MO than TiO{sub 2-x}N{sub x}. {yields} Holes, O{sub 2}{center_dot}{sup -}, and H{sub 2}O{sub 2} played an important role in the photocatalytic process. -- Abstract: AgInS{sub 2} nanoparticles with superior visible light photocatalytic activity were successfully synthesized by a microwave hydrothermal method. This method is a highly efficient and rapid route that involves no organic solvents, catalysts, or surfactants. The photocatalytic activity of AgInS{sub 2} nanoparticles was investigated through the degradation of dyes under visible light irradiation. Compared with TiO{sub 2-x}N{sub x}, AgInS{sub 2} has exhibited a superior activity for photocatalytic degradation MO under the same condition. The experiment results showed that superoxide radicals (O{sub 2}{center_dot}{sup -}), hydrogen peroxides (H{sub 2}O{sub 2}) and holes (h{sup +}) were the mainly active species for the degradation of organic pollutants over AgInS{sub 2}. Through the determination of flat band potential, the energy band structure of the sample was obtained. A possible mechanism for the degradation of organic pollutant over AgInS{sub 2} was proposed.

Zhang, Wenjuan [Research Institute of Photocatalysis, State Key Laboratory Breeding Base of Photocatalysis, Fuzhou University, Gongye Road No. 523, Fuzhou 350002, Fujian (China)] [Research Institute of Photocatalysis, State Key Laboratory Breeding Base of Photocatalysis, Fuzhou University, Gongye Road No. 523, Fuzhou 350002, Fujian (China); Li, Danzhen, E-mail: dzli@fzu.edu.cn [Research Institute of Photocatalysis, State Key Laboratory Breeding Base of Photocatalysis, Fuzhou University, Gongye Road No. 523, Fuzhou 350002, Fujian (China)] [Research Institute of Photocatalysis, State Key Laboratory Breeding Base of Photocatalysis, Fuzhou University, Gongye Road No. 523, Fuzhou 350002, Fujian (China); Chen, Zhixin; Sun, Meng; Li, Wenjuan; Lin, Qiang; Fu, Xianzhi [Research Institute of Photocatalysis, State Key Laboratory Breeding Base of Photocatalysis, Fuzhou University, Gongye Road No. 523, Fuzhou 350002, Fujian (China)] [Research Institute of Photocatalysis, State Key Laboratory Breeding Base of Photocatalysis, Fuzhou University, Gongye Road No. 523, Fuzhou 350002, Fujian (China)

2011-07-15

288

Phase-shifting the light-dark cycle influences food-anticipatory activity in golden shiners.  

PubMed

This study provides evidence that a circadian light-entrainable oscillator is at least partially involved in the timing of food-anticipatory activity (FAA) in a fish, the golden shiner, Notemigonus crysoleucas. Shoals of four golden shiners were fed for 11-20 days at a fixed daily time (either early night, midnight, late night, early day, midday, or late day). Most (78%) shoals developed peaks of FAA during that period of time. Food was then withheld for 7 days, and the light-dark (LD) cycle was either advanced or delayed by 6 h on the first of those days. The activity waveform of most (53-58%) shoals shifted along with the LD cycle, as indicated by significant correlation coefficients between pre- and postshift waveforms plotted relative to LD. Nonsignificant correlations were linked to low activity levels rather than to persistence of the activity peak at the old clock time. Activity shifts were gradual, taking 2-4 days, which indicates that the underlying mechanism is circadian rather than hourglass. PMID:10978478

Lague, M; Reebs, S G

289

Theoretical studies of floating-reference method for NIR blood glucose sensing  

NASA Astrophysics Data System (ADS)

Non-invasive blood glucose monitoring using NIR light has been suffered from the variety of optical background that is mainly caused by the change of human body, such as the change of temperature, water concentration, and so on. In order to eliminate these internal influence and external interference a so called floating-reference method has been proposed to provide an internal reference. From the analysis of the diffuse reflectance spectrum, a position has been found where diffuse reflection of light is not sensitive to the glucose concentrations. Our previous work has proved the existence of reference position using diffusion equation. However, since glucose monitoring generally use the NIR light in region of 1000-2000nm, diffusion equation is not valid because of the high absorption coefficient and small source-detector separations. In this paper, steady-state high-order approximate model is used to further investigate the existence of the floating reference position in semi-infinite medium. Based on the analysis of different optical parameters on the impact of spatially resolved reflectance of light, we find that the existence of the floating-reference position is the result of the interaction of optical parameters. Comparing to the results of Monte Carlo simulation, the applicable region of diffusion approximation and higher-order approximation for the calculation of floating-reference position is discussed at the wavelength of 1000nm-1800nm, using the intralipid solution of different concentrations. The results indicate that when the reduced albedo is greater than 0.93, diffusion approximation results are more close to simulation results, otherwise the high order approximation is more applicable.

Shi, Zhenzhi; Yang, Yue; Zhao, Huijuan; Chen, Wenliang; Liu, Rong; Xu, Kexin

2011-03-01

290

Daphnia (zoomed on floating blood cells; low light)  

NSDL National Science Digital Library

The black cells are actually the well-defined blood cells of the Daphnia. The pumping heart pumps these cells throughout the body. We are able to see these cells due to the zooming capability of a microscope.

Katie Hale (CSUF;Biological Sciences)

2007-07-18

291

Influence of green, red and blue light emitting diodes on multiprotein complex proteins and photosynthetic activity under different light intensities in lettuce leaves (Lactuca sativa L.).  

PubMed

The objective of this study was to investigate the response of light emitting diodes (LEDs) at different light intensities (70 and 80 for green LEDs, 88 and 238 for red LEDs and 80 and 238 ?mol m-2 s-1 for blue LEDs) at three wavelengths in lettuce leaves. Lettuce leaves were exposed to (522 nm), red (639 nm) and blue (470 nm) LEDs of different light intensities. Thylakoid multiprotein complex proteins and photosynthetic metabolism were then investigated. Biomass and photosynthetic parameters increased with an increasing light intensity under blue LED illumination and decreased when illuminated with red and green LEDs with decreased light intensity. The expression of multiprotein complex proteins including PSII-core dimer and PSII-core monomer using blue LEDs illumination was higher at higher light intensity (238 ?mol m-2 s-1) and was lowered with decreased light intensity (70-80 ?mol m-2 s-1). The responses of chloroplast sub-compartment proteins, including those active in stomatal opening and closing, and leaf physiological responses at different light intensities, indicated induced growth enhancement upon illumination with blue LEDs. High intensity blue LEDs promote plant growth by controlling the integrity of chloroplast proteins that optimize photosynthetic performance in the natural environment. PMID:24642884

Muneer, Sowbiya; Kim, Eun Jeong; Park, Jeong Suk; Lee, Jeong Hyun

2014-01-01

292

Influence of Green, Red and Blue Light Emitting Diodes on Multiprotein Complex Proteins and Photosynthetic Activity under Different Light Intensities in Lettuce Leaves (Lactuca sativa L.)  

PubMed Central

The objective of this study was to investigate the response of light emitting diodes (LEDs) at different light intensities (70 and 80 for green LEDs, 88 and 238 for red LEDs and 80 and 238 ?mol m?2 s?1 for blue LEDs) at three wavelengths in lettuce leaves. Lettuce leaves were exposed to (522 nm), red (639 nm) and blue (470 nm) LEDs of different light intensities. Thylakoid multiprotein complex proteins and photosynthetic metabolism were then investigated. Biomass and photosynthetic parameters increased with an increasing light intensity under blue LED illumination and decreased when illuminated with red and green LEDs with decreased light intensity. The expression of multiprotein complex proteins including PSII-core dimer and PSII-core monomer using blue LEDs illumination was higher at higher light intensity (238 ?mol m?2 s?1) and was lowered with decreased light intensity (70–80 ?mol m?2 s?1). The responses of chloroplast sub-compartment proteins, including those active in stomatal opening and closing, and leaf physiological responses at different light intensities, indicated induced growth enhancement upon illumination with blue LEDs. High intensity blue LEDs promote plant growth by controlling the integrity of chloroplast proteins that optimize photosynthetic performance in the natural environment. PMID:24642884

Muneer, Sowbiya; Kim, Eun Jeong; Park, Jeong Suk; Lee, Jeong Hyun

2014-01-01

293

Observations of pigment and particle distributions in the Western North Atlantic from an autonomous float and ocean color satellite  

E-print Network

1 Observations of pigment and particle distributions in the Western North Atlantic from, and depth and seasonal patterns associated with an increase in pigmentation per particle at low light such event in the float's record. This eddy was associated with weakly elevated surface pigment

Boss, Emmanuel S.

294

Morphological instability in a float zone  

NASA Technical Reports Server (NTRS)

This paper examines the morphological instability of the freezing interface of the float zone in a crystal sheet for which the height of the liquid zone L = Lf + Lm (where Lf and Lm are the planar positions of the solidifying and melting interfaces) is smaller than the width and the thickness of the sheet. The Lf and Lm positions are calculated, and basic state concentration profiles are determined for a planar interfacial system. A linear stability analysis of this system is performed showing that the growth rate of disturbances is a modified version of the growth rate for a directional solidification system. It was found that shorter melt zone configurations are less susceptible to long wavelength morphological instability, indicating that, to suppress morphological instability in a float zone system, it is necessary to decrease the liquid zone height.

Humphreys, Laura B.; Heminger, John A.; Young, Gerald W.

1990-01-01

295

Can Oil Float Completely Submerged in Water?  

E-print Network

Droplet formation in a system of two or more immiscible fluids is a celebrated topic of research in the fluid mechanics community. In this work, we propose an innovative phenomenon where oil when injected drop-wise into a pool of water moves towards the air-water interface where it floats in a fully submerged condition. The configuration, however, is not stable and a slight perturbation to the system causes the droplet to burst and float in partially submerged condition. The droplet contour is analyzed using edge detection. Temporal variation of a characteristic length of the droplet is analyzed using MATLAB image processing. The constraint of small Bond Number established the assumption of lubrication regime in the thin gap. A brief theoretical formulation also showed the temporal variation of the gap thickness

Nath, Saurabh; Chatterjee, Souvick

2013-01-01

296

OCD metrology by floating n/k  

NASA Astrophysics Data System (ADS)

In this paper, one of the major contributions to the OCD metrology error, resulting from within-wafer variation of the refractive index/extinction coefficient (n/k) of the substrate, is identified and quantified. To meet the required metrology accuracy for the 65-nm node and beyond, it is suggested that n/k should be floating when performing the regression for OCD modeling. A feasible way of performing such regression is proposed and verified. As shown in the presented example, the measured CDU (3?) with n/k fixed and n/k floating is 1.94 nm and 1.42 nm, respectively. That is, the metrology error of CDU committed by assuming n/k fixed is more than 35% of the total CDU.

Yu, Shinn-Sheng; Huang, Jacky; Ke, Chih-Ming; Gau, Tsai-Sheng; Lin, Burn J.; Yen, Anthony; Lane, Lawrence; Vuong, Vi; Chen, Yan

2007-03-01

297

Development of a Vsible-Light-Active Film for Direct Solar Energy Storage  

NASA Astrophysics Data System (ADS)

We conceived of a two-compartment photocatalytic assembly for direct storage of solar energy as chemical potential. Our approach was to maintain reductant and oxidant in separate compartments and develop a visible light (wavelength >400nm) photo-active film to effect an uphill photoreaction between compartments. A proton exchange membrane was included in the assembly to complete the electrical circuit. Towards obtaining a working prototype of the assembly, we developed a freeze-drying method to adhere visible-light photoactive nanoparticles to a self- standing, non-porous and conductive indium tin oxide-polyvinylidene difluoride (ITO-PVDF) support film, developed in-house. We explored the possibility of employing an iron-rich metal oxide as the photocatalytic component of the film and several were explored utilizing the sodium tartrate-assisted photoreduction of Cr(VI) to Cr(III). Although the Fe2O3-coated TiO2 nanoparticles were active for photoreduction, the initial reaction rate was modest and was slowed by substantial deactivation, making it unsuitable as a photo-active material for the composite film. A complete, two-compartment assembly was prepared using cadmium sulfide (CdS) and preliminarily examined for the Cr(VI) probe reaction, however, no catalytic activity was observed. To identify the reason(s) for this observation, further testing of the apparatus and the composite film is required.

Salazar, Audrey

298

Secular Light Curve of 2P/Encke: A Comet Active At Aphelion  

E-print Network

We present the secular light curve of comet 2P/Encke in two phase spaces, the log plot, and the time plot. The main conclusions of this work are: a) The comet shows activity at perihelion and aphelion, caused by two different active areas: Source 1, close to the South pole, active at perihelion, and Source 2, at the North pole, centered at aphelion. b) More than 18 physical parameters are measured from the secular light curves, many of them new, and are listed in the individual plots of the comet. Specifically we find for Source 1 the location of the turn on and turn off points of activity, RON= -1.63+-0.03 AU, ROFF= +1.49+-0.20 AU, TON= -87+-5 d, TOFF= +94+-15 d, the time lag, LAG(q)= 6+-1 d, the total active time, TACTIVITY= 181+-16 d, and the amplitude of the secular light curve, ASEC(1,1) = 4.8+-0.1 mag. c) From this information the photometric age and the time-age defined in Ferrin (Icarus 178, 493-516, 2005a, and Icarus, 185, 523-543, 2006), can be calculated, and we find P-AGE=97+-8 comet years and T-AGE= 103+-9 comet years (cy). Thus comet 2P/Encke is an old comet entering the methuselah stage (100 cy < age). d) The activity at aphelion (Source 2), extends for TACTIVITY = 815+-30 d and the amplitude of the secular light curve is ASEC (1,Q) = 3.0+-0.2 mag. e) From a new phase diagram an absolute magnitude and phase coefficient for the nucleus are determined, and we find RNUC(1,1,0)= 15.05+-0.14, and betha= 0.066+-0.003. From this data we find a nucleus effective diameter DEFFE = 5.12(+2.5;-1.7) km. These values are not much different from previous determinations but exhibit smaller errors. Additional results appear in the full abstract.

Ignacio Ferrin

2008-06-12

299

Secular light curve of 2P/Encke, a comet active at aphelion  

NASA Astrophysics Data System (ADS)

We present the secular light curve of Comet 2P/Encke in two phase spaces, the log plot, and the time plot. The main conclusions of this work are: (a) The comet shows activity at perihelion and aphelion, caused by two different active areas: Source 1, close to the south pole, active at perihelion, and Source 2, at the north pole, centered at aphelion. (b) More than 18 physical parameters are measured from the secular light curves, many of them new, and are listed in the individual plots of the comet. Specifically we find for Source 1 the location of the turn on and turn off points of activity, R=-1.63±0.03 AU, R=+1.49±0.20 AU, T=-87±5 d, T=+94±15 d, the time lag, LAG(q)=6±1 d, the total active time, T=181±16 d, and the amplitude of the secular light curve, A(1,1)=4.8±0.1 mag. (c) From this information the photometric age and the time-age defined in Ferrín [2005a. Icarus 178, 493-516; 2006. Icarus 185, 523-543], can be calculated, and we find P-AGE = 97 ± 8 comet years and T-AGE = 103 ± 9 comet years (cy). Thus Comet 2P/Encke is an old comet entering the methuselah stage (100 cy < age). (d) The activity at aphelion (Source 2), extends for T=815±30 d and the amplitude of the secular light curve is A(1,Q)=3.0±0.2 mag. (e) From a new phase diagram an absolute magnitude and phase coefficient for the nucleus are determined, and we find R(1,1,0)=15.05±0.14, and ?=0.066±0.003. From this data we find a nucleus effective diameter D=5.12(+2.5;-1.7) km. These values are not much different from previous determinations but exhibit smaller errors. (f) The activity of Source 1 is due to H 2O sublimation because it shows curvature. The activity of Source 2 might also be due to H 2O due to the circumstantial situation that the poles point to the Sun at perihelion and aphelion. (g) We found a photometric anomaly at aphelion, with minimum brightness between +393 and +413 days after perihelion that may be an indication of topography. (h) We have re-reduced the 1858 secular light curve of Kamel [1991. Icarus 93, 226-245]. There are secular changes in 7 physical parameters, and we achieve for the first time, an absolute age calibration. We find that the comet entered the inner Solar System and began sublimating in 1645±40 AD. (i) It is concluded that the secular light curve can place constraints on the pole orientation of the nucleus of some comets, and we measure the ecliptic longitude of the south pole of 2P/Encke equal to 213.2±4.5°, in excellent agreement with other determinations of this parameter, but with smaller error. (j) Using the observed absolute magnitude of 1858 and 2003 and a suitable theoretical model, the extinction date of the comet is determined. We obtain ED=2056±3 AD, implying that the comet's lifetime is 125±12 revolutions about the Sun after entering the inner Solar System.

Ferrín, Ignacio

2008-09-01

300

Free-floating atmospheric pressure ball plasmas  

Microsoft Academic Search

A long-lived (0.3 second, 10-20 cm diameter) ball plasma floating in the air above a water surface has been formed and studied in the laboratory. A 0.4 - 1 mF capacitor is charged to 4-5 kV, and subsequently discharged (30-60 Amps, 20-50 msec duration) into central copper cathode held fixed just below the surface of a bucket of water (with

G. A. Wurden; C. Ticos; Z. Wang; C. J. V. Wurden

2007-01-01

301

Floating Ice: Grades K-1: Illustrated Book  

NSDL National Science Digital Library

This informational text discusses the unique property of ice - that it floats in liquid water. Students focus on real-world examples and how ice is necessary for life in the polar regions. The text is written at a kindergarten through grade one reading level. This version is a full-color PDF that can be printed, cut and folded to form a book. Each book contains color photographs and illustrations.

Fries-Gaither, Jessica

302

Maintaining competency for float nursing staff.  

PubMed

Orienting staff to multiple areas is challenging, as is maintaining multiple competencies, which might be used infrequently. Creating a strategy to regularly assess needed competencies to maintain a highly skilled pool of nurses, prepared to float to multiple areas, is critical to supporting flexible staffing. A plan for how to achieve this complex analysis is described and can be translated to other complex environments. PMID:25036084

Overman, Kimberly; Hauver, Jeni; McKay, Jennifer; Aucoin, Julia

2014-01-01

303

Cryptochrome and Phytochrome Cooperatively but Independently Reduce Active Gibberellin Content in Rice Seedlings under Light Irradiation  

PubMed Central

In contrast to a wealth of knowledge about the photoregulation of gibberellin metabolism in dicots, that in monocots remains largely unclear. In this study, we found that a blue light signal triggers reduction of active gibberellin content in rice seedlings with simultaneous repression of two gibberellin 20-oxidase genes (OsGA20ox2 and OsGA20ox4) and acute induction of four gibberellin 2-oxidase genes (OsGA2ox4–OsGA2ox7). For further examination of the regulation of these genes, we established a series of cryptochrome-deficient lines through reverse genetic screening from a Tos17 mutant population and construction of knockdown lines based on an RNA interference technique. By using these lines and phytochrome mutants, we elucidated that cryptochrome 1 (cry1), consisting of two species in rice plants (cry1a and cry1b), is indispensable for robust induction of the GA2ox genes. On the other hand, repression of the GA20ox genes is mediated by phytochromes. In addition, we found that the phytochromes also mediate the repression of a gibberellin 3-oxidase gene (OsGA3ox2) in the light. These results imply that, in rice seedlings, phytochromes mediate the repression of gibberellin biosynthesis capacity, while cry1 mediates the induction of gibberellin inactivation capacity. The cry1 action was demonstrated to be dominant in the reduction of active gibberellin content, but, in rice seedlings, the cumulative effects of these independent actions reduced active gibberellin content in the light. This pathway design in which different types of photoreceptors independently but cooperatively regulate active gibberellin content is unique from the viewpoint of dicot research. This redundancy should provide robustness to the response in rice plants. PMID:22764280

Hirose, Fumiaki; Inagaki, Noritoshi; Hanada, Atsushi; Yamaguchi, Shinjiro; Kamiya, Yuji; Miyao, Akio; Hirochika, Hirohiko; Takano, Makoto

2012-01-01

304

FPP [Floating Potential Probe] Results, Final Report  

NASA Technical Reports Server (NTRS)

The Floating Potential Probe (FPP) operated on the International Space Station (ISS) from December 2000 to April 2001. During that time, it took many measurements of the ISS floating potential and the electron density and temperature. Those measurements were used as inputs to the Environments WorkBench (EWB) model of ISS potentials (originally developed by SAIC, but now sometimes called the Boeing model) that is used even today to predict charging levels for ISS. FPP is now completely defunct, having been removed and ejected from ISS. With the advent of the new Floating Potential Monitoring Unit (FPMU) on ISS, and the beginning of ISS operations with two large solar array panels instead of just one, a review of FPP measurements can offer comparisons with the new FPMU data and perhaps improve the accuracy of future ISS charging predictions. In particular, FPP measurements during times of low electron temperature and high electron density (the times of worst ISS charging) will be brought forward for comparison with the newly obtained FPMU data.

Ferguson, Dale C.

2007-01-01

305

Floating debris in the Mediterranean Sea.  

PubMed

Results from the first large-scale survey of floating natural (NMD) and anthropogenic (AMD) debris (>2 cm) in the central and western part of the Mediterranean Sea are reported. Floating debris was found throughout the entire study area with densities ranging from 0 to 194.6 items/km(2) and mean abundances of 24.9 AMD items/km(2) and 6.9 NMD items/km(2) across all surveyed locations. On the whole, 78% of all sighted objects were of anthropogenic origin, 95.6% of which were petrochemical derivatives (i.e. plastic and styrofoam). Maximum AMD densities (>52 items/km(2)) were found in the Adriatic Sea and in the Algerian basin, while the lowest densities (<6.3 items/km(2)) were observed in the Central Tyrrhenian and in the Sicilian Sea. All the other areas had mean densities ranging from 10.9 to 30.7 items/km(2). According to our calculations, more than 62 million macro-litter items are currently floating on the surface of the whole Mediterranean basin. PMID:25127501

Suaria, Giuseppe; Aliani, Stefano

2014-09-15

306

Capillary induced buckling of floating sheets  

NASA Astrophysics Data System (ADS)

When a water droplet is deposited over a thin floating sheet, radial wrinkles appear in the vicinity of the droplet as a result of capillary forces exerted at the contact line [1]. However, determining the stress state at the contact line is still challenging and limits the full description of the wrinkling pattern. In order to avoid this contact line ambiguities, we propose the experimental study of the buckling of a macroscopic annulus floating on the surface of water and submitted to a difference in surface tension between its inner and outer edges. This particular configuration allows to generate radial wrinkles on the membrane with well defined border conditions. The topography of the wrinkled patterns are precisely measured using a synthetic Schlieren technique. Based on the standard buckling theory, we develop scaling laws for the buckling threshold of the annulus as well as for the wave length and radial extension of the wrinkles, which are compared to our experimental results and numerical simulations. [4pt] [1] J. Huang, M. Juszkiewicz, W.H. de Jeu, E. Cerda, T. Emrick, N. Menon, and T.P. Russell. Capillary wrinkling of floating thin polymer films. Science, 317(5838):650-653, 2007.

Pineirua, Miguel; Bico, Jose; Roman, Benoit; Menon, Narayanan

2012-02-01

307

Visible-Light-Driven CO2 Reduction with Carbon Nitride: Enhancing the Activity of Ruthenium Catalysts.  

PubMed

A heterogeneous photocatalyst system that consists of a ruthenium complex and carbon nitride (C3 N4 ), which act as the catalytic and light-harvesting units, respectively, was developed for the reduction of CO2 into formic acid. Promoting the injection of electrons from C3 N4 into the ruthenium unit as well as strengthening the electronic interactions between the two units enhanced its activity. The use of a suitable solvent further improved the performance, resulting in a turnover number of greater than 1000 and an apparent quantum yield of 5.7?% at 400?nm. These are the best values that have been reported for heterogeneous photocatalysts for CO2 reduction under visible-light irradiation to date. PMID:25565575

Kuriki, Ryo; Sekizawa, Keita; Ishitani, Osamu; Maeda, Kazuhiko

2015-02-16

308

An in vitro thermal analysis during different light-activated hydrogen peroxide bleaching  

NASA Astrophysics Data System (ADS)

This study measured the critical temperature reaching time and also the variation of temperature in the surface of the cervical region and within the pulp chamber of human teeth submitted to dental bleaching using 35% hydrogen peroxide gel activated by three different light sources. The samples were randomly divided into 3 groups ( n = 15), according to the catalyst light source: Halogen Light (HL), High Intensity Diode Laser (DL), and Light Emmited Diode (LED). The results of temperature variation were submitted to the analysis of variance and Tukey test with p < 0.05. The temperature increase (mean value and standard deviation) inside the pulp chamber for the HL group was 6.8 ± 2.8°C; for the DL group was 15.3 ± 8.8°C; and for the LED group was 1.9 ± 1.0°C for. The temperature variation (mean value and standard deviation) on the tooth surface, for the group irradiated with HL was 9.1 ± 2.2°C; for the group irradiated with DL were 25.7 ± 18.9°C; and for the group irradiated with LED were 2.6 ± 1.4°C. The mean temperature increase values were significantly higher for the group irradiated with DL when compared with groups irradiated with HL and LED ( p < 0.05). When applying the inferior limits of the interval of confidence of 95%, an application time of 38.7 s was found for HL group, and 4.4 s for DL group. The LED group did not achieve the critical temperatures for pulp or the periodontal, even when irradiated for 360 s. The HL and DL light sources may be used for dental bleaching for a short period of time. The LED source did not heat the target tissues significantly within the parameters used in this study.

Kabbach, W.; Zezell, D. M.; Bandéca, M. C.; Pereira, T. M.; Andrade, M. F.

2010-09-01

309

FHY1 Mediates Nuclear Import of the Light-Activated Phytochrome A Photoreceptor  

PubMed Central

The phytochrome (phy) family of photoreceptors is of crucial importance throughout the life cycle of higher plants. Light-induced nuclear import is required for most phytochrome responses. Nuclear accumulation of phyA is dependent on two related proteins called FHY1 (Far-red elongated HYpocotyl 1) and FHL (FHY1 Like), with FHY1 playing the predominant function. The transcription of FHY1 and FHL are controlled by FHY3 (Far-red elongated HYpocotyl 3) and FAR1 (FAr-red impaired Response 1), a related pair of transcription factors, which thus indirectly control phyA nuclear accumulation. FHY1 and FHL preferentially interact with the light-activated form of phyA, but the mechanism by which they enable photoreceptor accumulation in the nucleus remains unsolved. Sequence comparison of numerous FHY1-related proteins indicates that only the NLS located at the N-terminus and the phyA-interaction domain located at the C-terminus are conserved. We demonstrate that these two parts of FHY1 are sufficient for FHY1 function. phyA nuclear accumulation is inhibited in the presence of high levels of FHY1 variants unable to enter the nucleus. Furthermore, nuclear accumulation of phyA becomes light- and FHY1-independent when an NLS sequence is fused to phyA, strongly suggesting that FHY1 mediates nuclear import of light-activated phyA. In accordance with this idea, FHY1 and FHY3 become functionally dispensable in seedlings expressing a constitutively nuclear version of phyA. Our data suggest that the mechanism uncovered in Arabidopsis is conserved in higher plants. Moreover, this mechanism allows us to propose a model explaining why phyA needs a specific nuclear import pathway. PMID:18670649

Genoud, Thierry; Schweizer, Fabian; Tscheuschler, Anke; Debrieux, Dimitry; Casal, Jorge J.; Schäfer, Eberhard; Hiltbrunner, Andreas; Fankhauser, Christian

2008-01-01

310

Double-doped TiO2 nanoparticles as an efficient visible-light-active photocatalyst and antibacterial agent under solar simulated light  

NASA Astrophysics Data System (ADS)

Silver and nitrogen doped TiO2 nanoparticles (NPs) were synthesized via sol-gel method. The physicochemical properties of the achieved NPs were characterized by various methods including X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultra violet-visible absorption spectroscopy (UV-vis). Both visible-light photocatalytic activity and antimicrobial properties were successfully demonstrated for the degradation of Rhodamine B (Rh. B.), as a model dye, and inactivation of Escherichia coli (E. coli), as a representative of microorganisms. The concentration of the employed dopant was optimized and the results revealed that the silver and nitrogen doped TiO2 NPs extended the light absorption spectrum toward the visible region and significantly enhanced the photodegradation of model dye and inactivation of bacteria under visible-light irradiation while double-doped TiO2 NPs exhibited highest photocatalytic and antibacterial activity compared with single doping. The significant enhancement in the photocatalytic activity and antibacterial properties of the double doped TiO2 NPs, under visible-light irradiation, can be attributed to the generation of two different electronic states acting as electron traps in TiO2 and responsible for narrowing the band gap of TiO2 and shifting its optical response from UV to the visible-light region.

Ashkarran, Ali Akbar; Hamidinezhad, Habib; Haddadi, Hedayat; Mahmoudi, Morteza

2014-05-01

311

Floating Oil-Spill Containment Device  

NASA Technical Reports Server (NTRS)

Previous oil containment booms have an open top that allows natural gas to escape, and have significant oil leakage due to wave action. Also, a subsea pyramid oil trap exists, but cannot move relative to moving oil plumes from deepsea oil leaks. The solution is to have large, moveable oil traps. One version floats on the sea surface and has a flexible tarp cover and a lower weighted skirt to completely entrap the floating oil and natural gas. The device must have at least three sides with boats pulling at each apex, and sonar or other system to track the slowly moving oil plume, so that the boats can properly locate the booms. The oil trap device must also have a means for removal of the oil and the natural gas. A second design version has a flexible pyramid cover that is attached by lines to ballast on the ocean floor. This is similar to fixed, metal pyramid oil capture devices in the Santa Barbara Channel off the coast of California. The ballast lines for the improved design, however, would have winches that can move the pyramid to always be located above the oil and gas plume. A third design is a combination of the first two. It uses a submerged pyramid to trap oil, but has no anchor and uses boats to locate the trap. It has ballast weights located along the bottom of the tarp and/or at the corners of the trap. The improved floating oil-spill containment device has a large floating boom and weighted skirt surrounding the oil and gas entrapment area. The device is triangular (or more than three sides) and has a flexible tarp cover with a raised gas vent area. Boats pull on the apex of the triangles to maintain tension and to allow the device to move to optimum locations to trap oil and gas. The gas is retrieved from a higher buoyant part of the tarp, and oil is retrieved from the floating oil layer contained in the device. These devices can be operated in relatively severe weather, since waves will break over the devices without causing oil leaking. Also, natural gas is entrapped and can be retrieved. All designs can use sonar to locate the moving oil plume, and then be relocated by using boats or winches to move the oil trapping devices. These devices can be constructed of treated, non-permeable DuPont Kevlar cloth (or similar material).

Jones, Jack A.

2012-01-01

312

Float processing of high-temperature complex silicate glasses and float baths used for same  

NASA Technical Reports Server (NTRS)

A float glass process for production of high melting temperature glasses utilizes a binary metal alloy bath having the combined properties of a low melting point, low reactivity with oxygen, low vapor pressure, and minimal reactivity with the silicate glasses being formed. The metal alloy of the float medium is exothermic with a solvent metal that does not readily form an oxide. The vapor pressure of both components in the alloy is low enough to prevent deleterious vapor deposition, and there is minimal chemical and interdiffusive interaction of either component with silicate glasses under the float processing conditions. Alloys having the desired combination of properties include compositions in which gold, silver or copper is the solvent metal and silicon, germanium or tin is the solute, preferably in eutectic or near-eutectic compositions.

Cooper, Reid Franklin (Inventor); Cook, Glen Bennett (Inventor)

2000-01-01

313

Monolithic crystalline cladding microstructures for efficient light guiding and beam manipulation in passive and active regimes  

PubMed Central

Miniature laser sources with on-demand beam features are desirable devices for a broad range of photonic applications. Lasing based on direct-pump of miniaturized waveguiding active structures offers a low-cost but intriguing solution for compact light-emitting devices. In this work, we demonstrate a novel family of three dimensional (3D) photonic microstructures monolithically integrated in a Nd:YAG laser crystal wafer. They are produced by the femtosecond laser writing, capable of simultaneous light waveguiding and beam manipulation. In these guiding systems, tailoring of laser modes by both passive/active beam splitting and ring-shaped transformation are achieved by an appropriate design of refractive index patterns. Integration of graphene thin-layer as saturable absorber in the 3D laser structures allows for efficient passive Q-switching of tailored laser radiations which may enable miniature waveguiding lasers for broader applications. Our results pave a way to construct complex integrated passive and active laser circuits in dielectric crystals by using femtosecond laser written monolithic photonic chips. PMID:25100561

Jia, Yuechen; Cheng, Chen; Vázquez de Aldana, Javier R.; Castillo, Gabriel R.; Rabes, Blanca del Rosal; Tan, Yang; Jaque, Daniel; Chen, Feng

2014-01-01

314

Monolithic crystalline cladding microstructures for efficient light guiding and beam manipulation in passive and active regimes  

NASA Astrophysics Data System (ADS)

Miniature laser sources with on-demand beam features are desirable devices for a broad range of photonic applications. Lasing based on direct-pump of miniaturized waveguiding active structures offers a low-cost but intriguing solution for compact light-emitting devices. In this work, we demonstrate a novel family of three dimensional (3D) photonic microstructures monolithically integrated in a Nd:YAG laser crystal wafer. They are produced by the femtosecond laser writing, capable of simultaneous light waveguiding and beam manipulation. In these guiding systems, tailoring of laser modes by both passive/active beam splitting and ring-shaped transformation are achieved by an appropriate design of refractive index patterns. Integration of graphene thin-layer as saturable absorber in the 3D laser structures allows for efficient passive Q-switching of tailored laser radiations which may enable miniature waveguiding lasers for broader applications. Our results pave a way to construct complex integrated passive and active laser circuits in dielectric crystals by using femtosecond laser written monolithic photonic chips.

Jia, Yuechen; Cheng, Chen; Vázquez de Aldana, Javier R.; Castillo, Gabriel R.; Rabes, Blanca Del Rosal; Tan, Yang; Jaque, Daniel; Chen, Feng

2014-08-01

315

RNA self-cleavage activated by ultraviolet light-induced oxidation  

PubMed Central

A novel UV-C-light-induced ribozyme activity was discovered within the highly structured 5?-genomic regions of both Hepatitis C Virus (HCV) and the related Classic Swine Fever Virus (CSFV). Cleavage is mediated by exposure to UV-C light but not by exogenous oxygen radicals. It is also very selective, occurring at base positions HCV C79 and CSFV A45 in some molecules and at the immediately adjacent 5?-positions HCV U78 and CSFV U44 in others. Among other reaction products, the majority of biochemically active products detected contained 3?-phosphate and 5?-phosphate-end groups at the newly generated termini, along with a much lower amount of 3?-hydroxyl end group. While preservation of an E-loop RNA structure in the vicinity of the cleavage site was a requisite for HCV RNA self-cleavage, this was not the case for CSFV RNA. The short size of the reactive domains (?33?nt), which are compatible with primitive RNA motifs, and the lack of sequence homology, indicate that as-yet unidentified UV-activated ribozymes are likely to be found throughout structured RNAs, thereby providing clues to whether early RNA self-cleavage events were mediated by photosensitive RNA structures. PMID:21989404

Ariza-Mateos, Ascensión; Prieto-Vega, Samuel; Díaz-Toledano, Rosa; Birk, Alex; Szeto, Hazel; Mena, Ignacio; Berzal-Herranz, Alfredo; Gómez, Jordi

2012-01-01

316

LIGHT MODULATION OF RUBISCO ACTIVATION IN SPECIES WITHOUT A LARGER ACTIVASE ISOFORM - EXISTANCE OF AN ACTIVASE REGULATORY PROTEIN?  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rubisco activase in some species like tobacco consists of only the shorter isoform. In Arabidopsis lack of the redox regulated, larger isoform results in an inability to modulate Rubisco activity in response to light intensity. However, light modulation can be observed in tobacco with characteristic...

317

Activation of the alternative pathway of complement by monoclonal lambda light chains in membranoproliferative glomerulonephritis  

PubMed Central

Immunopathological evidence suggests that activation of the alternative pathway of complement (AP) is involved in membranoproliferative glomerulonephritis (MPGN) and in immunoglobulin A nephropathy. In this report we describe an AP dysfunction-associated factor that was isolated from the serum and urine of a patient with hypocomplementemic MPGN. Extensive glomerular deposits of C3, properdin, and of the terminal complement components were observed in the kidney of the patient. In her serum the AP hemolytic activity was virtually absent. When mixed with fresh normal serum, the patient's serum induced a 96% C3 conversion during a 30-min incubation at +37 degrees C. This activity was found to be due to a circulating factor that by immunochemical characterization proved to be a 46-kD monoclonal immunoglobulin lambda light (L) chain dimer (lambda L). Purified lambda L, but not control lambda or kappa L chains from patients with L chain disease, activated the AP in a dose- and ionic strength-dependent manner. Functionally, lambda L was differentiated from C3 nephritic factor (an autoantibody against the AP C3 convertase, C3bBb) by its inability to bind to and stabilize the C3bBb enzyme. Instead, lambda L was observed to interact directly with the AP control factor H. Thus, lambda L represents a novel type of immunoglobulin-related AP- activating factor with the capacity to initiate alternative complement pathway activation in the fluid phase. PMID:1532415

1992-01-01

318

Phosphoenolpyruvate Carboxylase Kinase in Tobacco Leaves Is Activated by Light in a Similar but Not Identical Way as in Maize.  

PubMed Central

We have previously reported the partial purification of a Ca2+- independent phosphoenolpyruvate carboxylase (PEPC) protein-serine/threonine kinase (PEPC-PK) from illuminated leaves of N-sufficient tobacco (Nicotiana tabacum L.) plants (Y.-H. Wang, R. Chollet [1993] FEBS Lett 328: 215-218). We now report that this C3 PEPC-kinase is reversibly light activated in vivo in a time-dependent manner. As the kinase becomes light activated, the activity and L-malate sensitivity of its target protein increases and decreases, respectively. The light activation of tobacco PEPC-PK is prevented by pretreatment of detached leaves with various photosynthesis and cytosolic protein-synthesis inhibitors. Similarly, specific inhibitors of glutamine synthetase block the light activation of tobacco leaf PEPC-kinase under both photorespiratory and nonphotorespiratory conditions. This striking effect is partially and specifically reversed by exogenous glutamine, whereas it has no apparent effect on the light activation of the maize (Zea mays L.) leaf kinase. Using an in situ "activity-gel" phosphorylation assay, we have identified two major Ca2+-independent PEPC-kinase catalytic polypeptides in illuminated tobacco leaves that have the same molecular masses (approximately 30 and 37 kD) as found in illuminated maize leaves. Collectively, these results indicate that the phosphorylation of PEPC in N-sufficient leaves of tobacco (C3) and maize (C4) is regulated through similar but not identical light-signal transduction pathways. PMID:12226305

Li, B.; Zhang, X. Q.; Chollet, R.

1996-01-01

319

Floating and fixed artificial habitats: Spatial and temporal patterns of benthic communities in a coral reef environment  

NASA Astrophysics Data System (ADS)

While natural marine habitats with motion capabilities, e.g., kelps and seaweeds, have been studied alongside their associated fouling communities, little is known of the effect of motion on the communities of floating artificial habitats such as buoys, rafts, and pontoons, particularly in tropical systems. Hydrodynamic features greatly differ between floating and fixed artificial substrata, which in turn affect the structure of their associated communities. This study tested the hypothesis that floating and fixed artificial installations in a tropical reef system (Eilat, Red Sea) would support different benthic communities throughout space and time. Specifically, we examined differences in communities recruited onto settlement plates between floating and fixed installations deployed at three different sites, along a two-year monitoring period. The three sites exhibited distinct differences in species assemblages between the monitoring dates (6, 12, 18 and 24 months post deployment), mainly between the first and the last two dates. The average level of dissimilarity between floating and fixed installations increased over time at all sites. Over 50% of the dissimilarity between the floating and fixed installations resulted from five taxonomic groups i.e., bryozoans, bivalves, barnacles, sponges, including the amount of bare space on the settlement plates. The contribution of these groups to the dissimilarity changed both temporally within each site, and spatially among sites. The observed differences were related to the hydrodynamic characteristics of floating and fixed habitats, interacting with biotic features such as predation, successional processes and seasonality; and abiotic features including small-scale spatial changes, light, and position in the water column.

Perkol-Finkel, S.; Zilman, G.; Sella, I.; Miloh, T.; Benayahu, Y.

2008-04-01

320

Enhanced visible-light photocatalytic activity of active Al?O?/g-C?N? heterojunctions synthesized via surface hydroxyl modification.  

PubMed

Novel Al2O3/g-C3N4 heterojunction photocatalysts were fabricated through ultrasonic dispersion method. Al2O3, obtained via solution combustion, contained amorphous ingredient with lots of defect sites and was used as active component for transferring photo-induced electrons of g-C3N4. G-C3N4 was grafted surface hydroxyl groups in the presence of ammonia aqueous solution to combine with Al2O3 possessing positive charges via hydrogen bond. The XRD, SEM, element map, TEM, HRTEM, FT-IR, and XPS results indicate that these synthesized materials are two-phase hybrids of Al2O3 and g-C3N4 with interaction. The photocatalytic results for the degradation of rhodamine B (RhB) indicate that the most active heterojunction proportion is 60wt.% g-C3N4:40wt.% Al2O3, the visible light photocatalytic activity of which is 3.8 times that of a mechanical mixture. The enhanced performance is attributed to the high separation efficiency of photo-induced electrons from the LUMO of g-C3N4 injected into the defect sites of Al2O3, which is verified by photoluminescence spectroscopy (PL) and surface photovoltage (SPV) measurements. The electron paramagnetic resonance (EPR) signals and radical scavengers trapping experiments reveal holes (h(+)) and superoxide anion radical (O2(-)) are the main active species responsible for the degradation of RhB. PMID:25306536

Li, Fa-Tang; Zhao, Ye; Wang, Qing; Wang, Xiao-Jing; Hao, Ying-Juan; Liu, Rui-Hong; Zhao, Dishun

2015-02-11

321

Long distance active hyperspectral sensing using high-power near-infrared supercontinuum light source.  

PubMed

A hyperspectral remote sensing instrument employing a novel near-infrared supercontinuum light source has been developed for active illumination and identification of targets. The supercontinuum is generated in a standard normal dispersion multi-mode fiber and has 16 W total optical output power covering 1000 nm to 2300 nm spectral range. A commercial 256-channel infrared spectrometer was used for broadband infrared detection. The feasibility of the presented hyperspectral measurement approach was investigated both indoors and in the field. Reflection spectra from several diffusive targets were successfully measured and a measurement range of 1.5 km was demonstrated. PMID:24664065

Manninen, Albert; Kääriäinen, Teemu; Parviainen, Tomi; Buchter, Scott; Heiliö, Miika; Laurila, Toni

2014-03-24

322

Sensory Rhodopsin II from the Haloalkaliphilic Natronobacterium pharaonis: Light-Activated Proton Transfer Reactions  

Microsoft Academic Search

In the present work the light-activated proton transfer reactions of sensory rhodopsin II from Natronobacterium pharaonis (pSRII) and those of the channel-mutants D75N-pSRII and F86D-pSRII are investigated using flash photolysis and black lipid membrane (BLM) techniques. Whereas the photocycle of the F86D-pSRII mutant is quite similar to that of the wild-type protein, the photocycle of D75N-pSRII consists of only two

G. Schmies; B. Lüttenberg; I. Chizhov; M. Engelhard; A. Becker; E. Bamberg

2000-01-01

323

Light Modulation of the Activity of Carbon Metabolism Enzymes in the Crassulacean Acid Metabolism Plant Kalanchoë 1  

PubMed Central

When intact Kalanchoë plants are illuminated NADP-linked malic dehydrogenase and three enzymes of the reductive pentose phosphate pathway, ribulose-5-phosphate kinase, NADP-linked glyceraldehyde-3-phosphate dehydrogenase, and sedoheptulose-1,7-diphosphate phosphatase, are activated. In crude extracts these enzymes are activated by dithiothreitol treatment. Light or dithiothreitol treatment does not inactivate the oxidative pentose phosphate pathway enzyme glucose-6-phosphate dehydrogenase. Likewise, neither light, in vivo, nor dithiothreitol, in vitro, affects fructose-1,6-diphosphate phosphatase. Apparently the potential for modulation of enzyme activity by the reductively activated light effect mediator system exists in Crassulacean acid metabolism plants, but some enzymes which are light-dark-modulated in the pea plant are not in Kalanchoë. PMID:16660316

Gupta, Vimal K.; Anderson, Louise E.

1978-01-01

324

The effect on emotions and brain activity by the direct/indirect lighting in the residential environment.  

PubMed

This study was performed to explore how direct/indirect lighting affects emotions and brain oscillations compared to the direct lighting when brightness and color temperature are controlled. Twenty-eight subjects (12 females; mean age 22.5) participated. The experimental conditions consisted of two lighting environments: direct/indirect lighting (400lx downlight, 300lx uplight) and direct lighting (700lx downlight). On each trial, a luminance environment was presented for 4min, followed by participants rated their emotional feelings of the lighting environment. EEG data were recorded during the experiment. Spectral analysis was performed for the range of delta, theta, alpha, beta, and gamma ranges. The participants felt cooler and more pleasant and theta oscillations on the F4, F8, T4, and TP7 electrodes were more enhanced in the direct/indirect lighting environment compared to the direct lighting environment. There was significant correlation between the "cool" rating and the theta power of the F8 electrode. The participants felt more pleasant in the direct/indirect lighting environment, indicating that space with direct/indirect lighting modulated subjective perception. Additionally, our results suggest that theta oscillatory activity can be used as a biological marker that reflects emotional status in different lighting environments. PMID:25281545

Shin, Yu-Bin; Woo, Seung-Hyun; Kim, Dong-Hyeon; Kim, Jinseong; Kim, Jae-Jin; Park, Jin Young

2015-01-01

325

A light-activated metal complex targets both DNA and RNA in a fluorescent in vitro transcription and translation assay.  

PubMed

A coupled in vitro transcription and translation (IVTT) assay that uses GFP as a fluorescent reporter allowed the potency of a light-activated cytotoxic ruthenium agent to be quantified. The compound inhibits the function of both DNA and mRNA only upon light activation. The IVTT functional assay provides estimates of potency that are consistent with cellular cytotoxicity values, in marked contrast to the values obtained from traditional DNA-damage assays. PMID:24482049

Heidary, David K; Glazer, Edith C

2014-03-01

326

An Analysis of the Full-Floating Journal Bearing  

NASA Technical Reports Server (NTRS)

An analysis of the operating characteristics of a full-floating journal bearing, a bearing in which a floating sleeve is located between the journal and bearing surfaces, is presented together with charts from which the performance of such bearings may be predicted. Examples are presented to illustrate the use of these charts and a limited number of experiments conducted upon a glass full-floating bearing are reported to verify some results of the analysis.

Shaw, M C; Nussdorfer, T J , Jr

1947-01-01

327

Stability of Temperature and Conductivity Sensors of Argo Profiling Floats  

Microsoft Academic Search

After recalibration of the temperature and conductivity sensors of three Argo profiling floats recovered after operations\\u000a for four to nine months, the results indicate that the floats basically showed no significant drift, either in temperature\\u000a or salinity, and adequately fulfilled the accuracy requirement of the Argo project (0.005C for temperature and 0.01 psu for\\u000a salinity). Only the third float showed

Eitarou Oka; Kentaro Ando

2004-01-01

328

The amino terminal helix modulates light activated conformational changes in AsLOV2  

PubMed Central

The mechanism of light-triggered conformational change and signaling in light-oxygen-voltage (LOV) domains remains elusive in spite of extensive investigation and their use in optogenetic studies. The LOV2 domain of Avena Sativa phototropin1 (AsLOV2), a member of the Per-Arnt-Sim (PAS) family, contains an FMN chromophore that forms a covalent bond with a cysteine upon illumination. This event leads to the release of the carboxy terminal J? helix, the biological output signal. Using mutational analysis, circular dichroism and NMR, we find that the largely ignored amino terminal helix is a control element in AsLOV2’s light-activated conformational change. We further identify a direct amino-to-carboxy terminal “input-output” signaling pathway. These findings provide a framework to rationalize the LOV domain architecture, as well as the signaling mechanisms in both isolated and tandem arrangements of PAS domains. This knowledge can be applied in engineering LOV-based photoswitches, opening up new design strategies and improving existing ones. PMID:22406525

Zayner, Josiah P.; Antoniou, Chloe; Sosnick, Tobin R.

2012-01-01

329

Light activation of genotoxic components in natural and synthetic crude oils  

SciTech Connect

Undefined components in natural and synthetically-produced petroleums elicit a genotoxic response in cultured mammalian cells after exposure to light. The NUV component of the solar spectrum is the radiation responsible for photochemical transformation. The type(s) of lesion(s) induced in DNA by the photoactivation process is mimetic of FUV light-induced genotoxic lesions (bulky adduct-like) due to the similar sensitizing abilities of either insult in cells deficient in excision repair. Because of their intimate contact with the oil in the various stages associated with the production of shale oil, process waters contain significant quantities of uv-absorbing organic materials. Chemical fractionation of a process water has been achieved using an acid/base extraction scheme and reverse-phase HPLC. Resulting fractions have been assessed for photo-induced genotoxicity using a modification of the Ames/Salmonella bioassay in which NUV light is the source of activation in place of metabolic enzymes. Chemical identification of components in a photoactive peak fraction is in progress employing an additional class fractionation scheme and GC/MS methods.

Strniste, G.

1982-01-01

330

Photogelling colloidal dispersions based on light-activated assembly of nanoparticles.  

PubMed

Photorheological (PR) fluids, i.e., fluids whose rheology can be tuned by light, have been a recent focus for our laboratory. We are interested in low-cost approaches to PR fluids using molecules or materials that are readily available. Toward this end, we report a new concept for such fluids based on light-activated assembly of nanoparticles into a physical network (gel). Our system consists of disk-like nanoparticles of laponite along with a surfactant stabilizer (Pluronic F127) and the photoacid generator (PAG), diphenyliodonium-2-carboxylate monohydrate. Initially, the nanoparticles are sterically stabilized by the surfactant, and the result is a stable, low-viscosity dispersion. Upon UV irradiation, the PAG gets photolyzed, lowering the pH by approximately 3 units. In turn, the stabilizing surfactant is displaced from the negatively charged faces of the nanoparticle disks while the edges of the disks become positively charged. The particles are thereby induced to assemble into a three-dimensional "house-of-cards" network that extends through the sample volume. The net result is a light-induced sol to gel transition, i.e., from a low, water-like viscosity to an infinite viscosity and yield stress. The yield stress of the photogel is sufficiently high to support the weight of small objects. The gel can be converted back to a sol by increasing either the pH or the surfactant content. PMID:19405469

Sun, Kunshan; Kumar, Rakesh; Falvey, Daniel E; Raghavan, Srinivasa R

2009-05-27

331

Advances in recording scattered light changes in crustacean nerve with electrical activation  

SciTech Connect

We investigated optical changes associated with crustacean nerve stimulation using birefringent and large angle scattered light. Improved detection schemes disclosed high temporal structure of the optical signals and allowed further investigations of biophysical mechanisms responsible for such changes. Most studies of physiological activity in neuronal tissue use techniques that measure the electrical behavior or ionic permeability of the nerve, such as voltage or ion sensitive dyes injected into cells, or invasive electric recording apparatus. While these techniques provide high resolution, they are detrimental to tissue and do not easily lend themselves to clinical applications in humans. Electrical and chemical components of neural excitation evoke physical responses observed through changes in scattered and absorbed light. This method is suited for in-vivo applications. Intrinsic optical changes have shown themselves to be multifaceted in nature and point to several different physiological processes that occur with different time courses during neural excitation. Fast changes occur concomitantly with electrical events, and slow changes parallel metabolic events including changes in blood flow and oxygenation. Previous experiments with isolated crustacean nerves have been used to study the biophysical mechanisms of fast optical changes. However, they have been confounded by multiple superimposed action potentials which make it difficult to discriminate the temporal signatures of individual optical responses. Often many averages were needed to adequately resolve the signal. More recently, optical signals have been observed in single trials. Initially large angle scattering measurements were used to record these events with much of the signal coming from cellular swelling associated with water influx during activation. By exploiting the birefringent properties derived from the molecular stiucture of nerve membranes, signals appear larger with a greater contrast, but direct comparison of birefringent and 90{sup o} scattering signals has not been reported. New developments in computer and optical technology allow optical recording with higher temporal resolution than could be achieved previously. This has led us to undertake more detailed studies of the biophysical mechanisms underlying these transient changes. Optimization of this technology in conjunction with other technical developments presents a path to noninvasive dynamic clinical observation of optical responses. To conduct these optical recordings, we placed dissected leg, claw and ventral cord nerves from crayfish and lobster in a recording chamber constructed from black Delrin. The chamber consisted of several wells situated perpendicularly to the long axis of the nerve that could beelectrically isolated for stimulating and recording electrical activation, and a window in the center for optical measurements. To measure the birefringence from the nerve, light from a 120W halogen bulb was focused onto the nerve from below the window through a 10X microscope objective and polarized at a 45 degree angle with respect to the long axis of the nerve bundle. A second polarizer turned 90 degrees with respect to the first polarizer was placed on top of the chamber and excluded direct source illumination, passing only birefringent light from the nerve. A large area photodiode placed directly on top of the polarizer detected the magnitude of the birefringent light. To measure light scattered 90 degrees by the nerve, a short length of image conduit placed perpendicularly to the nerve directed large angle scattered light from the nerve to a second photodiode. The output of each photodiode was amplified by a first stage amplifier which produced a DC level output, and was coupled to an AC amplifier (0.3 Hz High Pass) with a gain of 1000 to optimally record changes across time.

Carter, K. M. (Kathleen M.); Rector, D. M. (David M.); Martinez, A. T. (Anne T.); Guerra, F. M. (Francisco M.); George, J. S. (John S.)

2002-01-01

332

Environment parameters and basic functions for floating-point computation  

NASA Technical Reports Server (NTRS)

A language-independent proposal for environment parameters and basic functions for floating-point computation is presented. Basic functions are proposed to analyze, synthesize, and scale floating-point numbers. The model provides a small set of parameters and a small set of axioms along with sharp measures of roundoff error. The parameters and functions can be used to write portable and robust codes that deal intimately with the floating-point representation. Subject to underflow and overflow constraints, a number can be scaled by a power of the floating-point radix inexpensively and without loss of precision. A specific representation for FORTRAN is included.

Brown, W. S.; Feldman, S. I.

1978-01-01

333

Floating Drug Delivery of Nevirapine as a Gastroretentive System  

PubMed Central

A multiple-unit floating drug delivery system based on gas formation technique was developed, in order to prolong the gastric residence time and to increase the overall bioavailability of the dosage form. The floating bead formulations were prepared by dispersing nevirapine together with calcium carbonate in a mixture of sodium alginate and hydroxypropyl methylcellulose solution and then dripping the dispersion into an acidified solution of calcium chloride. Calcium alginate beads were formed, as the alginate underwent ionotropic gelation by calcium ions, and carbon dioxide developed from the reaction of carbonate salts with acid. The obtained beads were able to float due to CO2-gas formation and the gas entrapment by the polymeric membrane. The prepared beads were evaluated for percent drug loading, drug entrapment efficiency, morphology, surface topography, buoyancy, in-vitro release, and release kinetics. The formulations were optimized for different weight ratios of the gas-forming agent and sodium alginate. The beads containing higher amounts of calcium carbonate demonstrated an instantaneous, complete, and excellent floating ability over a period of 24 hours. The increased amount of the gas forming agent did not affect the time to float, but increased the drug release from the floating beads, while increasing the coating level of the gas-entrapped membrane, increased the time to float, and slightly retarded the drug release. Good floating properties and sustained drug release were achieved. Finally, these floating beads seemed to be a promising gastroretentive drug delivery system. PMID:21264092

Vedha, Hari BN; Brahma, Reddy A; Samyuktha, Rani B

2010-01-01

334

[The method of phytoplankton photosynthesis activity in-situ measurement based on light induced fluorescence].  

PubMed

According to the phytoplankton fluorescence induction characteristics under different light conditions, chlorophyll fluorescence as a probe for analysis of phytoplankton photosynthesis was studied. The present paper proposed a in-situ measurement method based on the chlorophyll fluorescence values Ft and Fm to get phytoplankton photosynthesis activity, Chlorella vulgaris, microcystis aeruginosa and Cyclotella meneghiniana Kiits were selected as experimental subjects, a comparison test was done between self-developed in-situ measurement system and Water PAM in lab, and the results showed that coefficients between the two methods were 0.9778, 0.8786 and 0.7953. This work provides a rapid and in-situ measurement method for phytoplankton photosynthesis activity. PMID:24369649

Liu, Jing; Liu, Wen-qing; Zhao, Nan-jing; Zhang, Yu-jun; Ma, Ming-jun; Yin, Gao-fang; Dai, Pang-da; Wang, Zhi-gang; Wang, Chun-long; Duan, Jing-bo; Yu, Xiao-ya; Fang, Li

2013-09-01

335

Visible light activated ion sensing using a photoacid polymer for calcium detection.  

PubMed

Presented here is a sensing membrane consisting of a modified merocyanine photoacid polymer and a calcium ionophore in plasticized poly(vinyl chloride). This membrane is shown to actively exchange protons with calcium ions when switched ON after illumination at 470 nm, and the exchange can be followed by UV-vis spectroscopy. The sensing membrane shows no response in the ON state when calcium ions are absent. The limit of detection of the sensor is 5.0 × 10(-4) M with an upper detection limit of 1.0 M. Thus, we demonstrate for the first time the use of a visible light activated, lipophilic photoacid polymer in an ion-sensing membrane for calcium ions, which highly discriminates potassium, sodium, and magnesium ions. PMID:24893213

Johns, Valentine K; Patel, Parth K; Hassett, Shelly; Calvo-Marzal, Percy; Qin, Yu; Chumbimuni-Torres, Karin Y

2014-07-01

336

Locomotor activity in common spiny mice (Acomys cahirinuse): The effect of light and environmental complexity  

PubMed Central

Background Rodents typically avoid illuminated and open areas, favoring dark or sheltered environments for activity. While previous studies focused on the effect of these environmental attributes on the level of activity, the present study tested whether the spatio-temporal structure of activity was also modified in illuminated compared with dark and complex compared with open arenas. For this, we tested common spiny mice (Acomys cahirinus) in empty or stone-containing arenas with lights on or lights off. Results In an illuminated or open arena, spiny mice moved in less frequent but longer trips with relatively long distances between consecutive stops. In contrast, in either a dark arena or an arena with stones, the animals took shorter and more frequent trips, with more stops per trip and shorter inter-stop distances. In illuminated arenas spiny mice remained mainly along the walls, whereas locomotion in the center was more prevalent in dark empty arenas, and was carried out along convoluted paths. Increasing environmental complexity by adding stones to either illuminated or dark arenas increased locomotion along straight trajectories and away from walls. Conclusions Earlier findings of reduced activity in illuminated or open areas have been extended in the present study by demonstrating changes in the spatio-temporal structure of locomotor behavior. In the more complex arenas (with stones) spiny mice traveled along short straight segments whereas in the open their trips were longer and took the shape of a zigzag path which is more effective against fast or nearby predators. Alternatively, the zigzag path may reflect a difficulty in navigation. PMID:15537426

Eilam, David

2004-01-01

337

Activity Patterns of Eurasian Lynx Are Modulated by Light Regime and Individual Traits over a Wide Latitudinal Range.  

PubMed

The activity patterns of most terrestrial animals are regarded as being primarily influenced by light, although other factors, such as sexual cycle and climatic conditions, can modify the underlying patterns. However, most activity studies have been limited to a single study area, which in turn limit the variability of light conditions and other factors. Here we considered a range of variables that might potentially influence the activity of a large carnivore, the Eurasian lynx, in a network of studies conducted with identical methodology in different areas spanning latitudes from 49°7'N in central Europe to 70°00'N in northern Scandinavia. The variables considered both light conditions, ranging from a day with a complete day-night cycle to polar night and polar day, as well as individual traits of the animals. We analysed activity data of 38 individual free-ranging lynx equipped with GPS-collars with acceleration sensors, covering more than 11,000 lynx days. Mixed linear additive models revealed that the lynx activity level was not influenced by the daily daylight duration and the activity pattern was bimodal, even during polar night and polar day. The duration of the active phase of the activity cycle varied with the widening and narrowing of the photoperiod. Activity varied significantly with moonlight. Among adults, males were more active than females, and subadult lynx were more active than adults. In polar regions, the amplitude of the lynx daily activity pattern was low, likely as a result of the polycyclic activity pattern of their main prey, reindeer. At lower latitudes, the basic lynx activity pattern peaked during twilight, corresponding to the crepuscular activity pattern of the main prey, roe deer. Our results indicated that the basic activity of lynx is independent of light conditions, but is modified by both individual traits and the activity pattern of the locally most important prey. PMID:25517902

Heurich, Marco; Hilger, Anton; Küchenhoff, Helmut; Andrén, Henrik; Bufka, Lud?k; Krofel, Miha; Mattisson, Jenny; Odden, John; Persson, Jens; Rauset, Geir R; Schmidt, Krzysztof; Linnell, John D C

2014-01-01

338

Activity Patterns of Eurasian Lynx Are Modulated by Light Regime and Individual Traits over a Wide Latitudinal Range  

PubMed Central

The activity patterns of most terrestrial animals are regarded as being primarily influenced by light, although other factors, such as sexual cycle and climatic conditions, can modify the underlying patterns. However, most activity studies have been limited to a single study area, which in turn limit the variability of light conditions and other factors. Here we considered a range of variables that might potentially influence the activity of a large carnivore, the Eurasian lynx, in a network of studies conducted with identical methodology in different areas spanning latitudes from 49°7?N in central Europe to 70°00?N in northern Scandinavia. The variables considered both light conditions, ranging from a day with a complete day–night cycle to polar night and polar day, as well as individual traits of the animals. We analysed activity data of 38 individual free-ranging lynx equipped with GPS-collars with acceleration sensors, covering more than 11,000 lynx days. Mixed linear additive models revealed that the lynx activity level was not influenced by the daily daylight duration and the activity pattern was bimodal, even during polar night and polar day. The duration of the active phase of the activity cycle varied with the widening and narrowing of the photoperiod. Activity varied significantly with moonlight. Among adults, males were more active than females, and subadult lynx were more active than adults. In polar regions, the amplitude of the lynx daily activity pattern was low, likely as a result of the polycyclic activity pattern of their main prey, reindeer. At lower latitudes, the basic lynx activity pattern peaked during twilight, corresponding to the crepuscular activity pattern of the main prey, roe deer. Our results indicated that the basic activity of lynx is independent of light conditions, but is modified by both individual traits and the activity pattern of the locally most important prey. PMID:25517902

Heurich, Marco; Hilger, Anton; Küchenhoff, Helmut; Andrén, Henrik; Bufka, Lud?k; Krofel, Miha; Mattisson, Jenny; Odden, John; Persson, Jens; Rauset, Geir R.; Schmidt, Krzysztof; Linnell, John D. C.

2014-01-01

339

Structural Details of Light Activation of the LOV2-based Photoswitch PA-Rac1.  

PubMed

Optical control of cellular processes is an emerging approach for studying biological systems, affording control with high spatial and temporal resolution. Specifically designed artificial photoswitches add an interesting extension to naturally occurring light-regulated functionalities. However, despite a great deal of structural information, the generation of new tools cannot be based fully on rational design yet; in many cases design is limited by our understanding of molecular details of light activation and signal transduction. Our biochemical and biophysical studies on the established optogenetic tool PA-Rac1, the photoactivatable small GTPase Rac1, reveal how unexpected details of the sensor-effector interface, such as metal coordination, significantly affect functionally important structural elements of this photoswitch. Together with solution scattering experiments, our results favor differences in the population of pre-existing conformations as the underlying allosteric activation mechanism of PA-Rac1, rather than the assumed release of the Rac1 domain from the caging photoreceptor domain. These results have implications for the design of new optogenetic tools and highlight the importance of including molecular details of the sensor-effector interface, which is however difficult to assess during the initial design of novel artificial photoswitches. PMID:25368973

Winkler, Andreas; Barends, Thomas R M; Udvarhelyi, Anikó; Lenherr-Frey, Daniel; Lomb, Lukas; Menzel, Andreas; Schlichting, Ilme

2014-11-17

340

A toolbox of Cre-dependent optogenetic transgenic mice for light-induced activation and silencing  

PubMed Central

Cell-type-specific expression of optogenetic molecules allows temporally precise manipulation of targeted neuronal activity. Here we present a toolbox of 4 knock-in mouse lines engineered for strong, Cre-dependent expression of channelrhodopsins ChR2-tdTomato and ChR2-EYFP, halorhodopsin eNpHR3.0, and archaerhodopsin Arch-ER2. All 4 transgenes mediate Cre-dependent, robust activation or silencing of cortical pyramidal neurons in vitro and in vivo upon light stimulation, with ChR2-EYFP and Arch-ER2 demonstrating light sensitivity approaching that of in utero or virally transduced neurons. We further show specific photoactivation of parvalbumin-positive interneurons in behaving ChR2-EYFP reporter mice. The robust, consistent, and inducible nature of our ChR2 mice represents a significant advancement over previous lines, whereas the Arch-ER2 and eNpHR3.0 mice are the first demonstration of successful conditional transgenic optogenetic silencing. When combined with the hundreds of available Cre-driver lines, this optimized toolbox of reporter mice will enable widespread investigations of neural circuit function with unprecedented reliability and accuracy. PMID:22446880

Madisen, Linda; Mao, Tianyi; Koch, Henner; Zhuo, Jia-min; Berenyi, Antal; Fujisawa, Shigeyoshi; Hsu, Yun-Wei A.; Garcia, Alfredo J.; Gu, Xuan; Zanella, Sebastien; Kidney, Jolene; Gu, Hong; Mao, Yimei; Hooks, Bryan M.; Boyden, Edward S.; Buzsáki, György; Ramirez, Jan Marino; Jones, Allan R.; Svoboda, Karel; Han, Xue; Turner, Eric E.; Zeng, Hongkui

2012-01-01

341

Dark/Light modulation of ribulose bisphosphate carboxylase activity in plants from different photosynthetic categories.  

PubMed

Ribulose bisphosphate carboxylase/oxygenase (RuBPCase) from several plants had substantially greater activity in extracts from lightexposed leaves than dark leaves, even when the extracts were incubated in vitro with saturating HCO(3) (-) and Mg(2+) concentrations. This occurred in Glycine max, Lycopersicon esculentum, Nicotiana tabacum, Panicum bisulcatum, and P. hylaeicum (C(3)); P. maximum (C(4) phosphoenolpyruvate carboxykinase); P. milioides (C(3)/C(4)); and Bromelia pinguin and Ananas comosus (Crassulacean acid metabolism). Little or no difference between light and dark leaf extracts of RuBPCase was observed in Triticum aestivum (C(3)); P. miliaceum (C(4) NAD malic enzyme); Zea mays and Sorghum bicolor (C(4) NADP malic enzyme); Moricandia arvensis (C(3)/C(4)); and Hydrilla verticillata (submersed aquatic macrophyte). It is concluded that, in many plants, especially Crassulacean acid metabolism and C(3) species, a large fraction of ribulose-1,5-bisphosphate carboxylase/oxygenase in the dark is in an inactivatable state that cannot respond to CO(2) and Mg(2+) activation, but which can be converted to an activatable state upon exposure of the leaf to light. PMID:16663937

Vu, J C; Allen, L H; Bowes, G

1984-11-01

342

Parallel Optical Control of Spatiotemporal Neuronal Spike Activity Using High-Speed Digital Light Processing  

PubMed Central

Neurons in the mammalian neocortex receive inputs from and communicate back to thousands of other neurons, creating complex spatiotemporal activity patterns. The experimental investigation of these parallel dynamic interactions has been limited due to the technical challenges of monitoring or manipulating neuronal activity at that level of complexity. Here we describe a new massively parallel photostimulation system that can be used to control action potential firing in in vitro brain slices with high spatial and temporal resolution while performing extracellular or intracellular electrophysiological measurements. The system uses digital light processing technology to generate 2-dimensional (2D) stimulus patterns with >780,000 independently controlled photostimulation sites that operate at high spatial (5.4??m) and temporal (>13?kHz) resolution. Light is projected through the quartz–glass bottom of the perfusion chamber providing access to a large area (2.76?mm?×?2.07?mm) of the slice preparation. This system has the unique capability to induce temporally precise action potential firing in large groups of neurons distributed over a wide area covering several cortical columns. Parallel photostimulation opens up new opportunities for the in vitro experimental investigation of spatiotemporal neuronal interactions at a broad range of anatomical scales. PMID:21904526

Jerome, Jason; Foehring, Robert C.; Armstrong, William E.; Spain, William J.; Heck, Detlef H.

2011-01-01

343

Early-light embryonic stimulation suggests a second route, via gene activation, to cerebral lateralization in vertebrates  

PubMed Central

Genetic factors determine the asymmetrical position of vertebrate embryos allowing asymmetric environmental stimulation to shape cerebral lateralization. In birds, late-light stimulation, just before hatching, on the right optic nerve triggers anatomical and functional cerebral asymmetries. However, some brain asymmetries develop in absence of embryonic light stimulation. Furthermore, early-light action affects lateralization in the transparent zebrafish embryos before their visual system is functional. Here we investigated whether another pathway intervenes in establishing brain specialization. We exposed chicks' embryos to light before their visual system was formed. We observed that such early stimulation modulates cerebral lateralization in a comparable vein of late-light stimulation on active retinal cells. Our results show that, in a higher vertebrate brain, a second route, likely affecting the genetic expression of photosensitive regions, acts before the development of a functional visual system. More than one sensitive period seems thus available to light stimulation to trigger brain lateralization. PMID:24048072

Chiandetti, Cinzia; Galliussi, Jessica; Andrew, Richard J.; Vallortigara, Giorgio

2013-01-01

344

Visible-light Photocatalytic Activity of Titanium Dioxide/Bismuth Ferrite Heterostructures  

NASA Astrophysics Data System (ADS)

Ferroelectric polarization is believed to enhance the efficiency of a semiconductor photocatalyst, including ferroelectric/semiconductor heterojunction photocatalysts. BiFeO3, which has a narrow band gap of ?2.2 - 2.7 eV and can absorb visible light, is investigated as a ferroelectric substrate that supports a TiO2 film in a photocatalytic heterostructure. The photocatalytic activity of the TiO2/BiFeO3 heterostructure is studied in detail, using visible light irradiation. The photochemical reduction of Ag+ to Ag0 in an aqueous silver nitrate solution under illumination from a blue light emitting diode is used to characterize the activity of the heterostructures and related samples. The photocatalytic activity is quantified by measuring the heights of the reduction products using atomic force microscopy. The observation of spatially selective silver patterns on the surface of the heterostructure after reaction suggests that electrons photogenerated in the BiFeO3 substrate migrate, under the influence of ferroelectric polarization, to the TiO2 surface, where they participate in the photochemical reduction reaction. This is supported by the correlation of the reduced silver pattern and the ferroelectric domain structure as revealed by piezoresponse force microscopy (PFM). To establish correlation between out-of-plane polarity of domains and photochemical activity for both bare BiFeO3 and TiO2/BiFeO3, analysis of domain structures using PFM responses and crystallographic orientation information and comparison to reactivity patterns are made. To study the dependence of photocatalytic activity of the heterostructures on the TiO2 phase and orientation, the orientation relationships (ORs) of TiO2 and BiFeO3 are determined via the Combinatorial Substrate Epitaxy technique using electron backscatter diffraction data of each grain in a heterostructure having a thick TiO2 film on a polycrystalline BiFeO3 substrate. It is found that the three dimensional alignment of closest packed planes and directions of TiO2 and BiFeO 3 drives the epitaxial growth regardless of their interface planes. As a result, anatase grows on BiFeO3 with the OR (112)A || (111)BFO and [11¯0]A || [11¯0]BFO within 35° of [100]BFO. Rutile grows on other BiFeO 3 orientations with (100)R || (111)BFO, and with in-plane orientation being primarily [001]R || [11¯0] BFO and secondarily [001]R || [1¯21¯]BFO. Comparisons of the amounts of reduced silver on TiO2 film grains with distinct phases/orientations show that the heterostructure reactivity is approximately the same on anatase and rutile grains and is not strongly affected by the crystallographic orientation of both phases, an observation that contrasts the behavior of bulk TiO2 (under UV irradiation) but is in agreement with the behavior of UV-light absorbing ferroelectric / titania heterostructures. Collectively these observations demonstrated that TiO2 heterostructures can be engineered with visible light absorbing sensitizers that spatially separate the oxidation and reduction reaction, which will increase overall efficiencies.

Zhang, Yiling

345

Science Teachers Without Classrooms of Their Own: A Study of the Phenomenon of Floating  

NASA Astrophysics Data System (ADS)

"Floating" teachers, or teachers without their own classroom, experience unique affordances and constraints as they develop professionally. To increase the knowledge in this area, this study looks at how traveling to different classrooms affects beginning secondary science teachers' development and instruction. The participants in this study were three first-year floating secondary science teachers whose experiences were analyzed through a cultural historical activity theory framework. The data revealed how floating can either support or constrain the development of beginning science teachers, and limit the implementation of standards-based instruction. Finally, this study shows that high levels of human, physical, and social resources are necessary for progress towards standards-based science teaching. It suggests that if science teachers must move to different classrooms, we need to create ways in which to support their instruction and development. Furthermore, this study recommends that all teachers and supervisors work toward a deeper understanding of the school community's role in the experience of the floating science teacher.

Dubois, Shannon L.; Luft, Julie A.

2014-02-01

346

Solution-Processed Nanoparticle Super-Float-Gated Organic Field-Effect Transistor as Un-cooled Ultraviolet and Infrared Photon Counter  

PubMed Central

High sensitivity photodetectors in ultraviolet (UV) and infrared (IR) range have broad civilian and military applications. Here we report on an un-cooled solution-processed UV-IR photon counter based on modified organic field-effect transistors. This type of UV detectors have light absorbing zinc oxide nanoparticles (NPs) sandwiched between two gate dielectric layers as a floating gate. The photon-generated charges on the floating gate cause high resistance regions in the transistor channel and tune the source-drain output current. This “super-float-gating” mechanism enables very high sensitivity photodetectors with a minimum detectable ultraviolet light intensity of 2.6?photons/?m2s at room temperature as well as photon counting capability. Based on same mechansim, infrared photodetectors with lead sulfide NPs as light absorbing materials have also been demonstrated. PMID:24048259

Yuan, Yongbo; Dong, Qingfeng; Yang, Bin; Guo, Fawen; Zhang, Qi; Han, Ming; Huang, Jinsong

2013-01-01

347

Development and in vivo floating behavior of verapamil HCl intragastric floating tablets.  

PubMed

A novel gastro retentive controlled release drug delivery system of verapamil HCl was formulated in an effort to increase the gastric retention time of the dosage form and to control drug release. Hydroxypropylmethylcellulose (HPMC), carbopol, and xanthan gum were incorporated for gel-forming properties. Buoyancy was achieved by adding an effervescent mixture of sodium bicarbonate and anhydrous citric acid. In vitro drug release studies were performed, and drug release kinetics was evaluated using the linear regression method. The optimized intragastric floating tablet composed of 3:2 of HPMC K4M to xanthan gum exhibited 95.39% drug release in 24 h in vitro, while the buoyancy lag time was 36.2 s, and the intragastric floating tablet remained buoyant for >24 h. Zero-order and non-Fickian release transport was confirmed as the drug release mechanism from the optimized formulation (F7). X-ray studies showed that total buoyancy time was able to delay the gastric emptying of verapamil HCl intragastric floating tablet in mongrel dogs for more than 4 h. Optimized intragastric floating tablet showed no significant change in physical appearance, drug content, total buoyancy time, or in vitro dissolution pattern after storage at 40 degrees C/75% relative humidity for 3 months. PMID:19296224

Patel, Anand; Modasiya, Moin; Shah, Dushyant; Patel, Vishnu

2009-01-01

348

Fluorescent light activates the immunomodulator cis-urocanic acid in vitro: implications for patients with systemic lupus erythematosus.  

PubMed Central

OBJECTIVE--Erythemagenic (295-305 nm) ultraviolet-B (UVB) radiation is toxic to patients with systemic lupus erythematosus (SLE). Cool white fluorescent lamp emissions produce a similar toxicity even though the UVB radiation emitted is primarily at the relatively non-erythemagenic wavelength of 313 nm. The purpose of this study was to determine if fluorescent light, presumably acting predominantly along the 313 nm wavelength, exhibits photochemical activity sufficient to account for toxicity. METHODS--The photochemical activity of fluorescent light was assessed by testing its capacity to activate urocanic acid, a plentiful and potent epidermal immunological mediator normally activated by polychromatic UVB radiation but activated maximally at 313 nm. Irradiation-induced isomerisation of trans-urocanic to cis-urocanic acid was quantitated by UV spectroscopy after separation of the isomers by high performance liquid chromatography. RESULTS--Fluorescent light irradiation of solutions containing the photoreceptor trans-urocanic acid produced a cumulative conversion of trans-to-cis-urocanic acid. This photochemical activity was compared with that of erythemagenic sunlamps, high in polychromatic UVB emissions. When normalised for UVB irradiance, the accumulation of cis-urocanic acid produced by both light sources was essentially equivalent. Conventional acrylic diffusers that absorb UVB emissions eliminated the fluorescent light-induced reaction. CONCLUSION--The results indicate that radiation from fluorescent lamps possesses substantial photoimmunological capability, sufficient to activate a potent, potentially dangerous, disease-modifying, immunomodulatory pathway and that poorly erythemagenic, primarily monochromatic UVB photons are responsible. PMID:8037497

McGrath, H; Bell, J M; Haycock, J W

1994-01-01

349

Research effort aims at floating production technology  

SciTech Connect

This paper reports that a 3 year research and development program on floating production systems (FPS), instigated by the Royal Norwegian Council for Scientific and Industrial Research (NTNF), has refined and qualified technologies for North Sea and arctic conditions. The FPS 2000 program, which cost 58 million kroner ($10 million), concentrated mainly on mooring systems and pipeline technology, along with new system concepts and cost reduction measures. More than 30 projects have been completed within the scheme. The anchoring and positioning project concentrates on developing methods for simulating behavior of mooring systems for large volume structures in deep water. It also seeks ways to determine efficiency of dynamic positioning thrusters under extreme conditions.

Not Available

1992-08-17

350

Floating hydrometer with energy dissipating baffle  

SciTech Connect

This patent describes a floating hydrometer employable for purposes of obtaining measurements of the presence of suspended solids in a fluid substance contained in a receptacle comprising: a. a probe portion operative as an instrument-bearing housing; b. an elongated tubular element having a hollow interior and at least one open end so as to enable the flow into the hollow interior of the elongated tubular element through the open end; and c. energy dissipating baffle means having a first mode of action and a second mode of action and including a member having a hollow interior.

Kownurko, W.A.

1987-11-24

351

Floating production unit to work off Brazil  

SciTech Connect

This paper reports that Petroleo Brasileiro SA expects by early November to deploy its Petrobras XXIV floating production unit (FPU) in about 900 ft of water in Albacora field off Brazil. The FPU was scheduled to depart Galveston, Tex., this month, following completion of modifications and upgrades under a turnkey contract with Chiles Offshore International Inc. Chiles began modifying Petrobras XXIV about 1 year ago as part of a deal closed in October 1991 in which Chiles Offshore Corp. sold the vessel, then known as Intrepid, to Brasoil, the international subsidiary of Petrobras.

Not Available

1992-10-19

352

An integrated circuit floating point accumulator  

NASA Technical Reports Server (NTRS)

Goddard Space Flight Center has developed a large scale integrated circuit (type 623) which can perform pulse counting, storage, floating point compression, and serial transmission, using a single monolithic device. Counts of 27 or 19 bits can be converted to transmitted values of 12 or 8 bits respectively. Use of the 623 has resulted in substantial savaings in weight, volume, and dollar resources on at least 11 scientific instruments to be flown on 4 NASA spacecraft. The design, construction, and application of the 623 are described.

Goldsmith, T. C.

1977-01-01

353

Biological activity of particle exhaust emissions from light-duty diesel engines.  

PubMed

Whole diesel exhaust has been classified recently as a probable carcinogen, and several genotoxicity studies have found particulate exhaust to be clearly mutagenic. Moreover, genotoxicity of diesel particulate is greatly influenced by fuel nature and type of combustion. In order to obtain an effective environmental pollution control, combustion processes using alternative fuels are being analyzed presently. The goal of this study is to determine whether the installation of exhaust after treatment-devices on two light-duty, exhaust gas recirculation (EGR) valve-equipped diesel engines (1930 cc and 2500 cc) can reduce the mutagenicity associated with particles collected during U.S.A. and European driving cycles. Another interesting object was to compare the ability of alternative biodiesel and conventional diesel fuels to reduce the mutagenic activity associated with collected particles from two light duty diesel engines (both 1930 cc) during the European driving cycle. SOF mutagenicity was assayed using the Salmonella/microsome test (TA 98 and TA 100 strains, +/- S9 fraction). In the first part of our study, the highest mutagenicity was revealed by TA98 strain without enzymatic activation, suggesting a direct-acting mutagenicity prevalence in diesel particulate. The 2500 cc engine revealed twofold mutagenic activity compared with the 1930 cc engine (both EGR valve equipped), whereas an opposite result was found in particulate matter amount. The use of a noncatalytic ceramic trap produced a decrease of particle mutagenic activity in the 2500 cc car, whereas an enhancement in the 1930 cc engine was found. The catalytic converter and the electrostatic filter installed on the 2500 cc engine yielded a light particle amount and an SOF mutagenicity decrease. A greater engine stress was obtained using European driving cycles, which caused the strongest mutagenicity/km compared with the U.S.A. cycles. In the second part of the investigation, even though a small number of assays were available, exhaust emission generation by biodiesel fuel seemed to yield a smaller environmental impact than that of the referenced diesel fuel. The results point out the usefulness of mutagenicity testing in the research of both newer, more efficient automotive aftertreatment devices and less polluting fuels. PMID:9275990

Carraro, E; Locatelli, A L; Ferrero, C; Fea, E; Gilli, G

1997-01-01

354

Light activated, In situ Forming Gel for Sustained Suprachoroidal Delivery of Bevacizumab  

PubMed Central

Purpose To develop a light activated polycaprolactone dimethacrylate and hydroxyethyl methacrylate based gel network that sustains the release of stable, active bevacizumab (an anti-VEGF antibody used to treat choroidal neovascularization) and to assess sustained ex vivo delivery in rabbit eyes and in vivo delivery in rat eyes following in situ gel formation in the suprachoroidal space. Methods Polycaprolactone dimethacrylate (PCM) was synthesized from polycaprolactone diol (PCD) and evaluated using NMR spectroscopy. PCM was used to cross-link hydroxyethyl methacrylate (HEMA) in the presence of 365 nm UV light and 2, 2-dimethoxy-2-phenylacetophenone (DMPA) as a photoinitiator. Bevacizumab was entrapped in the gel using 3 different cross-linking durations of 3, 7, and 10 minutes. In vitro release of bevacizumab in PBS pH 7.4 at 37°C during a 4 months study was quantified using a VEGF-binding based ELISA. Stability of released bevacizumab was monitored by size exclusion chromatography (SEC) and circular dichroism. Alexa Fluor® 488 dye conjugated bevacizumab mixed with polymers was injected suprachoroidally in rabbit eyes to study the effect of different cross-linking durations on the spread of the dye conjugated bevacizumab. In vivo delivery was assessed in Sprague Dawley (SD) rats by injecting Alexa Fluor® 488 dye conjugated bevacizumab mixed with polymers followed by cross-linking for 10 minutes. Spread in the rabbit eyes and in vivo delivery in rat eyes was monitored noninvasively using a fundus camera and Fluorotron Master™. Results Formation of PCM was confirmed by the disappearance of hydroxyl peak in NMR spectra. Cross-linking duration of 10 minutes resulted in a burst release of 21 % of bevacizumab. Other cross-linking durations had ? 62 % burst release. Bevacizumab release from 10 minute cross-linked gel was sustained for ? 4 months. Release samples contained ? 96.1 % of bevacizumab in the monomeric form as observed in SEC chromatograms. Circular dichroism confirmed that secondary ?-sheet structure of bevacizumab was maintained after release from the gel. As the cross-linking duration was increased to 10 minutes, the gel/antibody was better confined at the injection site in excised rabbit eye suprachoroidal space. Delivery of Alexa Fluor® 488 dye conjugated bevacizumab was sustained for at least 60 days in the suprachoroidal space of SD rats. Conclusion PCM and HEMA gel sustained bevacizumab release for 4 months and maintained the stability and VEGF-binding activity of bevacizumab. Light activated PCM and HEMA gel is suitable for in situ gel formation and sustained protein delivery in the suprachoroidal space. PMID:23734705

Tyagi, Puneet; Barros, Matthew; Stansbury, Jeffrey W.; Kompella, Uday B.

2014-01-01

355

UV light activates a G?q/11-coupled phototransduction pathway in human melanocytes.  

PubMed

While short exposure to solar ultraviolet radiation (UVR) can elicit increased skin pigmentation, a protective response mediated by epidermal melanocytes, chronic exposure can lead to skin cancer and photoaging. However, the molecular mechanisms that allow human skin to detect and respond to UVR remain incompletely understood. UVR stimulates a retinal-dependent signaling cascade in human melanocytes that requires GTP hydrolysis and phospholipase C ? (PLC?) activity. This pathway involves the activation of transient receptor potential A1 (TRPA1) ion channels, an increase in intracellular Ca(2+), and an increase in cellular melanin content. Here, we investigated the identity of the G protein and downstream elements of the signaling cascade and found that UVR phototransduction is G?q/11 dependent. Activation of G?q/11/PLC? signaling leads to hydrolysis of phosphatidylinositol (4,5)-bisphosphate (PIP2) to generate diacylglycerol (DAG) and inositol 1, 4, 5-trisphosphate (IP3). We found that PIP2 regulated TRPA1-mediated photocurrents, and IP3 stimulated intracellular Ca(2+) release. The UVR-elicited Ca(2+) response appears to involve both IP3-mediated release from intracellular stores and Ca(2+) influx through TRPA1 channels, showing the fast rising phase of the former and the slow decay of the latter. We propose that melanocytes use a UVR phototransduction mechanism that involves the activation of a G?q/11-dependent phosphoinositide cascade, and resembles light phototransduction cascades of the eye. PMID:24470488

Bellono, Nicholas W; Najera, Julia A; Oancea, Elena

2014-02-01

356

UV light activates a G?q/11-coupled phototransduction pathway in human melanocytes  

PubMed Central

While short exposure to solar ultraviolet radiation (UVR) can elicit increased skin pigmentation, a protective response mediated by epidermal melanocytes, chronic exposure can lead to skin cancer and photoaging. However, the molecular mechanisms that allow human skin to detect and respond to UVR remain incompletely understood. UVR stimulates a retinal-dependent signaling cascade in human melanocytes that requires GTP hydrolysis and phospholipase C ? (PLC?) activity. This pathway involves the activation of transient receptor potential A1 (TRPA1) ion channels, an increase in intracellular Ca2+, and an increase in cellular melanin content. Here, we investigated the identity of the G protein and downstream elements of the signaling cascade and found that UVR phototransduction is G?q/11 dependent. Activation of G?q/11/PLC? signaling leads to hydrolysis of phosphatidylinositol (4,5)-bisphosphate (PIP2) to generate diacylglycerol (DAG) and inositol 1, 4, 5-trisphosphate (IP3). We found that PIP2 regulated TRPA1-mediated photocurrents, and IP3 stimulated intracellular Ca2+ release. The UVR-elicited Ca2+ response appears to involve both IP3-mediated release from intracellular stores and Ca2+ influx through TRPA1 channels, showing the fast rising phase of the former and the slow decay of the latter. We propose that melanocytes use a UVR phototransduction mechanism that involves the activation of a G?q/11-dependent phosphoinositide cascade, and resembles light phototransduction cascades of the eye. PMID:24470488

Bellono, Nicholas W.; Najera, Julia A.

2014-01-01

357

Bismuth titanate pyrochlore microspheres: Directed synthesis and their visible light photocatalytic activity  

SciTech Connect

Bismuth titanates, Bi{sub 2}Ti{sub 2}O{sub 7} (BIT), with well-defined spherical structures were synthesized by a facile hydrothermal process without the use of any surfactant or template. XRD and SEM studies have shown that spheres could be fabricated in high yields by simply manipulating the concentrations of hydroxide ions. In this case, hydroxide ions seem to play a pivotal role in controlling the formation of seeds and growth rates of the BIT particles. On the basis of structural analysis of samples obtained at different concentrations of OH{sup -}, we also proposed a plausible mechanism to account for the formation of these distinctive morphologies under different conditions. The as-prepared BIT microspheres with good stability exhibited higher photocatalytic activities in the degradation of Rhodamine B (RhB) under visible light irradiation than that in commercial P25 TiO{sub 2}. Furthermore, the enhanced photocatalytic performance for RhB degradation was also investigated with assistance of a small amount of H{sub 2}O{sub 2}. -- Graphical abstract: Bismuth titanate pyrochlore microspheres were synthesized by a facile hydrothermal process without the use of any surfactant or template, and the effects of concentration of OH{sup -} on the diameter of microspheres, growth mechanism and photocatalytic properties were investigated. Display Omitted Research Highlights: Bismuth titanate pyrochlore microspheres with different diameters were synthesized by a facile hydrothermal process without the use of any surfactant or template. The BIT microspheres with good stability exhibited higher photocatalytic activities in the degradation of RhB under visible light irradiation than that in commercial P25 TiO{sub 2}. Further enhanced photocatalytic activity for RhB degradation was ascribed to the assistance of a small amount of H{sub 2}O{sub 2}.

Hou, Jungang, E-mail: hjgwolf2004@163.co [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Jiao, Shuqiang; Zhu, Hongmin [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Kumar, R.V. [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ (United Kingdom)

2011-01-15

358

Informal Activities with Lasers, Lights, and Lenses: The Hands-On Optics Project  

NASA Astrophysics Data System (ADS)

The Hands-On Optics project began as a follow-up to the 2001 NSF planning grant "Optics Education -- A Blueprint for the 21st Century", which described the value of informal science programs in addressing the disconnect between the ubiquity of optics in everyday life and the noticeable absence of optics education in K-12 curricula and in informal science education programs. Key partners in the project are NOAO, SPIE-The International Society for Optical Engineering, and the Optical Society of America (OSA). The informal instructional materials created by the project are distributed through science centers nationwide and through the Mathematics, Engineering, Science Achievement Program (MESA) in a number of states, including Arizona, California, Washington, and Maryland. A key part of the project is the involvement, modeled after Project ASTRO, of optics professionals currently engaged in outreach activities and programs. Optics professionals (termed optics resource volunteers) are teamed with MESA and science center educators in implementing the program. These hands-on, high-interest, standards-connected activities and materials provide 6, three-hour-long optics activity modules that can be used in a variety of informal settings. We will describe the techniques used at NOAO to train educators, parents, and optics professionals who will work with the HOO activities as well as the different approaches needed for different informal education programs, ranging from Saturday programs, after-school programs, and science center programs. NOAO is developing the six modules and associated kits as well as competitions that have broad appeal to 12-year olds. Hands-On Optics: Making an Impact with Light (HOO) is a collaborative NSF-funded four-year informal science education program to excite students about science by actively engaging them in optics activities. NOAO is operated by the Association of Universities for Research in Astronomy (AURA), Inc. under cooperative agreement with the National Science Foundation.

Pompea, S. M.; Sparks, C. E.; Sparks, R. T.

2005-12-01

359

Development of bilayer floating tablet of amoxicillin and Aloe vera gel powder for treatment of gastric ulcers.  

PubMed

Usual treatment for Helicobacter pylori-induced peptic ulcer includes a 'triple therapy' consisting of two antibiotics (amoxicillin and clarithromycin) and a proton pump inhibitor (omeprazole). The objective of this project work was defined with a view to retain the drug in stomach for better antiulcer activity and substituting one of the synthetic drugs in this therapy with a herbal alternative. Hence, aim of the present work was to design and develop a bilayer floating tablet of amoxicillin and Aloe vera gel powder for the treatment of peptic ulcer. A. vera gel powder is used for its cytoprotective action. Bilayer floating tablets were prepared by applying direct compression technique. The proportion of sodium bicarbonate and citric acid was adjusted to get the least possible lag time with good matrix integrity and total floating time. Polymer concentration was adjusted to get the maximum release in 8 h. The formulation was developed using hydroxypropyl methyl cellulose (HPMC) K4M and HPMC K100M in a ratio of 85:15 along with 1:4 ratio of effervescent agents was found to give floating lag time of less than 1 min with total floating time of more than 8 h and 97.0% drug release in 8 h. In vivo study in rats meets the requirement of antiulcer activity for bilayer tablet in comparison to single amoxicillin as standard. PMID:23135966

Ranade, Arati N; Wankhede, Sonali S; Ranpise, Nisharani S; Mundada, Mayur S

2012-12-01

360

Translation of Chloroplast psbA mRNA Is Modulated in the Light by Counteracting Oxidizing and Reducing Activities  

PubMed Central

Light has been proposed to stimulate the translation of Chlamydomonas reinhardtii chloroplast psbA mRNA by activating a protein complex associated with the 5? untranslated region of this mRNA. The protein complex contains a redox-active regulatory site responsive to thioredoxin. We identified RB60, a protein disulfide isomerase-like member of the protein complex, as carrying the redox-active regulatory site composed of vicinal dithiol. We assayed in parallel the redox state of RB60 and translation of psbA mRNA in intact chloroplasts. Light activated the specific oxidation of RB60, on the one hand, and reduced RB60, probably via the ferredoxin-thioredoxin system, on the other. Higher light intensities increased the pool of reduced RB60 and the rate of psbA mRNA translation, suggesting that a counterbalanced action of reducing and oxidizing activities modulates the translation of psbA mRNA in parallel with fluctuating light intensities. In the dark, chemical reduction of the vicinal dithiol site did not activate translation. These results suggest a mechanism by which light primes redox-regulated translation by an unknown mechanism and then the rate of translation is determined by the reduction-oxidation of a sensor protein located in a complex bound to the 5? untranslated region of the chloroplast mRNA. PMID:10648596

Trebitsh, Tova; Levitan, Alex; Sofer, Anat; Danon, Avihai

2000-01-01

361

Free floating planets in stellar clusters?  

E-print Network

We have simulated encounters between planetary systems and single stars in various clustered environments. This allows us to estimate the fraction of systems liberated, the velocity distribution of the liberated planets, and the separation and eccentricity distributions of the surviving bound systems. Our results indicate that, for an initial distribution of orbits that is flat in log space and extends out to 50AU, 50% of the available planets can be liberated in a globular cluster, 25% in an open cluster, and less than 10% in a young cluster. These fractions are reduced to 25%, 12% and 2% if the initial population extends only to 20AU. Furthermore, these free-floating planets can be retained for longer than a crossing time only in a massive globular cluster. It is therefore difficult to see how planets, which by definition form in a disc around a young star, could be subsequently liberated to form a significant population of free floating substellar objects in a cluster.

Kester W. Smith; Ian A. Bonnell

2001-01-05

362

Thermal Performance of the LDX Floating Coil  

NASA Astrophysics Data System (ADS)

The Levitated Dipole Experiment (LDX) is an innovative facility to study plasma confinement in a dipole magnetic field, created by a superconducting solenoid (floating coil), which is magnetically levitated in the center of a 5 m diameter by 3 m tall vacuum chamber. The floating coil (F-coil) consists of a Nb3Sn magnet installed inside a strong vessel filled with high-pressure helium gas at room temperature. It is surrounded by a fiberglass-lead composite radiation shield and by a toroidal vacuum shell. The cryostat design provides the ability to operate the magnet for several hours of wanning while suspended in the middle of the vacuum chamber without electric and cryogenic connections to the coil. For this reason the magnet is charged/discharged inductively in a lower part of the vacuum chamber. The retractable cryogenic transfer lines serve to cool down the magnet to 4.5 K before it is lifted to the operating position. The F-coil can be re-cooled multiple times while maintaining its field and current. This paper describes the thermal performance of the F-coil.

Zhukovsky, A.; Garnier, D. T.; Radovinsky, A. L.

2006-04-01

363

Floating treatment wetlands for domestic wastewater treatment.  

PubMed

Floating islands are a form of treatment wetland characterized by a mat of synthetic matrix at the water surface into which macrophytes can be planted and through which water passes. We evaluated two matrix materials for treating domestic wastewater, recycled plastic and recycled carpet fibers, for chemical oxygen demand (COD) and nitrogen removal. These materials were compared to pea gravel or open water (control). Experiments were conducted in laboratory scale columns fed with synthetic wastewater containing COD, organic and inorganic nitrogen, and mineral salts. Columns were unplanted, naturally inoculated, and operated in batch mode with continuous recirculation and aeration. COD was efficiently removed in all systems examined (>90% removal). Ammonia was efficiently removed by nitrification. Removal of total dissolved N was ?50% by day 28, by which time most remaining nitrogen was present as NO(3)-N. Complete removal of NO(3)-N by denitrification was accomplished by dosing columns with molasses. Microbial communities of interest were visualized with denaturing gradient gel electrophoresis (DGGE) by targeting specific functional genes. Shifts in the denitrifying community were observed post-molasses addition, when nitrate levels decreased. The conditioning time for reliable nitrification was determined to be approximately three months. These results suggest that floating treatment wetlands are a viable alternative for domestic wastewater treatment. PMID:22105133

Faulwetter, J L; Burr, M D; Cunningham, A B; Stewart, F M; Camper, A K; Stein, O R

2011-01-01

364

What every computer scientist should know about floating-point arithmetic  

Microsoft Academic Search

Floating-point arithmetic is considered as esoteric subject by many people. This is rather surprising, because floating-point is ubiquitous in computer systems: Almost every language has a floating-point datatype; computers from PCs to supercomputers have floating-point accelerators; most compilers will be called upon to compile floating-point algorithms from time to time; and virtually every operating system must respond to floating-point exceptions

David Goldberg

1991-01-01

365

Sustainable molecular oxygen activation with oxygen vacancies on the {001} facets of BiOCl nanosheets under solar light  

NASA Astrophysics Data System (ADS)

We demonstrate that oxygen vacancies on the {001} facets of BiOCl nanosheets can more sustainably activate molecular oxygen for organic pollutant removal under solar light than the TiO2 counterparts. The oxygen vacancies on the {001} facets of BiOCl nanosheets are effectively refreshed by UV light, and are also responsible for the efficient utilization of visible light to activate molecular oxygen, accounting for their long term stability and high efficiency.We demonstrate that oxygen vacancies on the {001} facets of BiOCl nanosheets can more sustainably activate molecular oxygen for organic pollutant removal under solar light than the TiO2 counterparts. The oxygen vacancies on the {001} facets of BiOCl nanosheets are effectively refreshed by UV light, and are also responsible for the efficient utilization of visible light to activate molecular oxygen, accounting for their long term stability and high efficiency. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04810e

Li, Hao; Shi, Jingu; Zhao, Kun; Zhang, Lizhi

2014-11-01

366

Ultraviolet light and osmotic stress: Activation of the JNK cascade through multiple growth factor and cytokine receptors  

SciTech Connect

Exposure of mammalian cells to ultraviolet (UV) light or high osmolarity strongly activated the c-Jun amino-terminal protein kinase (JNK) cascade, causing induction of many target genes. Exposure to UV light or osmotic shock induced clustering and internalization of cell surface receptors for epidermal growth factor (EGF), tumor necrosis factor (TNF), and interleukin-1 (IL-1). Activation of the EGF and TNF receptors was also detected biochemically. Whereas activation of each receptor alone resulted in modest activation of JNK, coadministration of EGF, IL-1, and TNF resulted in a strong synergistic response equal to that caused by exposure to osmotic shock or UV light. Inhibition of clustering or receptor down-regulation attenuated both the osmotic shock and UV responses. Physical stresses may perturb the cell surface or alter receptor conformation, thereby subverting signaling pathways normally used by growth factors and cytokines. 24 refs., 5 figs.

Rosette, C.; Karin, M. [Univ. of California, La Jolla, CA (United States)] [Univ. of California, La Jolla, CA (United States)

1996-11-15

367

Deep ultraviolet emitting polarization induced nanowire light emitting diodes with AlxGa1?xN active regions  

NASA Astrophysics Data System (ADS)

In this report, we demonstrate band gap tuning of the active region emission wavelength from 365 nm to 250 nm in light emitting diodes fashioned from catalyst-free III-nitride nanowires. Optical characteristics of the nanowire heterostructures and fabricated devices are studied via electroluminescence (EL) and photoluminescence spectroscopy over a wide range of active region compositions. It is observed that for typical nanowire plasma assisted molecular beam epitaxy growth conditions, tuning of emission to wavelengths shorter than 300 nm is hampered by the presence of an optically active defect level. We show that by increasing the AlGaN nanowire growth temperatures this defect emission can be suppressed. These findings are applied to growth of the active region of a nanowire light emitting diode, resulting in a polarization-induced nanowire light emitting diode with peak EL at 250 nm.

Kent, Thomas F.; Carnevale, Santino D.; Sarwar, A. T. M.; Phillips, Patrick J.; Klie, Robert F.; Myers, Roberto C.

2014-11-01

368

A Web Resource for Lab Activities Using SEM, EDX and Light Microscopy  

NASA Astrophysics Data System (ADS)

A resource that facilitates undergraduate activities centered on the development of perthitic textures is available at http://www.geosci.ipfw.edu/sem/semedx.html. The web site provides a coherent set of data and images from a perthite and an anorthoclase sample. Backscatter and secondary electron images, plane- and cross-polarized light images, energy dispersive X-ray (EDX) data from 13 points on the perthite and 31 points on the anorthoclase (including spectra and results files with data expressed as wt. and atomic percents) and X-ray diffraction (XRD) data are available. Care has been taken to match the areas examined by light and electron methods, allowing students to directly compare the data available from each technique. Brief descriptions of the various methods are provided. The available information can be the basis for many different exercises. Those without easy access to mircoprobes or EDX spectrometers will find the spectra useful for discussions of microchemical techniques. Different phases can be identified in the light and SEM images. The chemical results can be used to calculate formulas. (In addition to the feldspar, the anorthoclase phenocryst contains olivine, clinopyroxene, ulvospinel, apatite and glass.) Feldspar compositions can be plotted to illustrate compositional differences in perthite and anorthoclase. Glass compositions from the interior and margins of the anorthoclase phenocrysts can be compared. Numerous other possibilities, of varying levels of complexity, exist. The perthite (from Perth, Ontario) and the anorthoclase (from Mt. Erebus, Antarctica) were purchased from Wards Natural Science. There are many students with little or no access to data derived from EDX, SEM, XRD and similar techniques. It is our responsibility to find ways to make this information more universally available to all students.

Argast, A.; Tennis, C. F.

2003-12-01

369

Cellular Trojan horse based polymer nanoreactors with light-sensitive activity.  

PubMed

Stimulus-sensitive systems at the nanoscale represent ideal candidates for improving therapeutic and diagnostic approaches by producing rapid responses to the presence of specific molecules or conditions either by changing properties or by acting "on demand". Here we introduce an optimized light-sensitive nanoreactor based on encapsulation of a photosensitizer inside polymer vesicles to serve as an efficient source of reactive oxygen species (ROS) "on demand". Two types of amphiphilic block copolymers, poly(2-methyloxazoline)-block-poly(dimethylsiloxane)-block-poly(2-methyloxazoline), PMOXA-PDMS-PMOXA, and poly(N-vinylpyrrolidone)-block-poly(dimethylsiloxane)-block-poly(N-vinylpyrrolidone), PNVP-PDMS-PNVP, were used to encapsulate Rose Bengal-bovine serum albumin (RB-BSA) inside the cavity of vesicles. The difference of copolymers molecular properties (hydrophobic to hydrophilic ratio, different chemical nature of the hydrophilic block) influenced the encapsulation ability, and uptake by cells, allowing therefore a selection of the most efficient polymer system. Nanoreactors were optimized in terms of (i) size, (ii) stability, and (iii) encapsulation efficiency based on a combination of light scattering, TEM, and UV-vis spectroscopy. By illumination, encapsulated RB-BSA conjugates generated in situ ROS, which diffused through the polymer membrane to the environment of the vesicles, as proved by electron spin resonance spectroscopy (ESR). Optimum illumination conditions were obtained based on the effect of the illumination time on the amount of ROS produced in situ by the encapsulated RB-BSA conjugates. ROS diffusion monitored by ESR was dependent on the molecular weight of copolymer that influences the thickness of the polymer membrane. Upon uptake into HeLa cells our nontoxic nanoreactors acted as a Trojan horse: they produced illumination-controlled ROS in sufficient amounts to induce cell death under photodynamic therapy (PDT) conditions. Straightforward production, stability, and Trojan horse activity inside cells support our light-sensitive nanoreactors for medical applications which require ROS to be generated with precise time and space control. PMID:25045828

Baumann, Patric; Spulber, Mariana; Dinu, Ionel Adrian; Palivan, Cornelia G

2014-08-01

370

New Ce3+-activated thiosilicate phosphor for LED lighting-synthesis, luminescence studies, and applications.  

PubMed

A new Ce(3+)-activated thiosilicate phosphor, BaLa2Si2S8:Ce(3+), was synthesized by using solid-state methods in a fused silica ampule and found to crystallize in the structure type of La2PbSi2S8. The crystal structure has been characterized by synchrotron X-ray diffraction and refined with Rietveld methods. This novel cyan-emitting phosphor can be excited over a broad range from UV to blue light (380-450 nm) and generates a broadband emission peaking at 471 nm with a quantum efficiency of 36%. Nonradiative transitions between Ce(3+) ions in BaLa2Si2S8:Ce(3+) have also been demonstrated to be attributable to dipole-dipole interactions, and the critical distance was calculated to be 17.41 Å. When BaLa2Si2S8:Ce(3+) phosphor was utilized to incorporate with yellow-emitting (Sr,Ca)2SiO4:Eu(2+) phosphor and red-emitting CaAlSiN3:Eu(2+) phosphor on a 430 nm blue LED chip, a warm white light LED device with color rendering index of ?96 was obtained. The results indicate that cyan-emitting BaLa2Si2S8:Ce(3+) can serve as a potential phosphor for incorporation in fabrication of solid-state lighting. The preparation, spectroscopic characterization, quantum efficiency, decay lifetime, thermal-quenching behavior, and related LED device data are also presented. PMID:24766496

Lee, Szu-Ping; Huang, Chien-Hao; Chan, Ting-Shan; Chen, Teng-Ming

2014-05-28

371

Argo at PMEL: Intro http://floats.pmel.noaa.gov  

E-print Network

) ·End-to-end (Float providers involved in instrumentation development, preparation & testing, deployment at PMEL: Float Preparation ·Suite of tests developed with academic colleagues & manufacturers and data quality -Inspect exterior, seals, &components -Check weight -Test transmitter, oil pump, vacuum

372

Floating gate power supply of multilevel converters for circuit integration  

Microsoft Academic Search

There is the possibility of the intrinsic elimination of harmonics and electromagnetic interference (EMI) by introducing multilevel converters with a large number of levels. As the number of levels increases, the number of the main switching devices on their higher side increases, and their floating gate power supplies become larger scale circuits. Because it is necessary to integrate the floating

Masamu Kamaga; Kyungmin Sung; Jin Xu; Yukihiko Sato; Hiromichi Ohashi

2009-01-01

373

Evaluating Energy Efficiency of Floating Point Matrix Multiplication on FPGAs  

E-print Network

Evaluating Energy Efficiency of Floating Point Matrix Multiplication on FPGAs Kiran Kumar Matam, prasanna}@usc.edu Abstract--Energy efficiency has emerged as one of the key performance metrics in scientific computing. In this work, we evaluate the energy efficiency of floating point matrix multipli

Prasanna, Viktor K.

374

Apollo 9 spacecraft floats in Atlantic recovery area after splashdown  

NASA Technical Reports Server (NTRS)

Apollo 9 spacecraft floats in the Atlantic recovery area after splashdown to conclude a successful ten-day, earth-orbital space mission. Splashdown occurred at 12:00:53 p.m., March 13, 1969. Notice the spent parachutes floating on the water's surface near the capsule.

1969-01-01

375

22. Float located adjacent to entry stair in filtration bed. ...  

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

22. Float located adjacent to entry stair in filtration bed. The float actuates a valve that maintains water level over the bed. - Lake Whitney Water Filtration Plant, Filtration Plant, South side of Armory Street between Edgehill Road & Whitney Avenue, Hamden, New Haven County, CT

376

Submarine Floating Antenna Model for LORAN-C Signal  

E-print Network

Submarine Floating Antenna Model for LORAN-C Signal Processing A. MONIN LAAS-CNRS France An electromagnetic model of the floating antenna used by submarines for LORAN-C radionavigation and very low The antenna used by submarines, for LORAN-C radionavigation and very low frequency (VLF) communications

Monin, André

377

A FLOATING-FISH SNARE FOR CAPTURING BALD EAGLES  

Microsoft Academic Search

Bald Eagles (Haliaeetus leucocephalus) were captured using a system of 4 monofilament snares fixed on a small (20-24 cm) floating fish attached by monofilament and shock cord to a free- floating (or anchored) driftwood log. When an eagle strikes the bait and begins to fly away, the snare loops close around the bird's toes as the line tightens. Resistance of

STEVEN L. CAIN; JOHN I. HODGES

378

Laser light scattering spectroscopy: a new method to measure tracheobronchial mucociliary activity  

Microsoft Academic Search

Laser light scattering spectroscopy is based on the evaluation of the frequency shift of coherent light scattered by moving particles. This makes it particularly suitable for use in light guiding systems. In this study laser light scattering spectroscopy was assessed for its ability to provide information on the motility of respiratory cilia. In vitro and in vivo measurements were undertaken

K Svartengren; L G Wiman; P Thyberg; R Rigler

1989-01-01

379

Fullerene modification CdSe/TiO2 and modification of photocatalytic activity under visible light  

PubMed Central

CdSe, CdSe-TiO2, and CdSe-C60/TiO2 composites were prepared using sol–gel method, and their photocatalytic activity was evaluated by measuring the degradation of rhodamine B solutions under visible light. The surface area, surface structure, crystal phase, and elemental identification of these composites were characterized by nitrogen adsorption isotherms, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), and UV-visible (vis) absorption spectrophotometry. XRD showed that the CdSe-C60/TiO2 composite contained a typical single and clear anatase phase. SEM of the CdSe-C60/TiO2 composites revealed a homogenous composition in the particles. EDX revealed the presence of C and Ti with strong Cd and Se peaks in the CdSe-C60/TiO2 composite. The degradation of dye was determined by UV–vis spectrophotometry. An increase in photocatalytic activity was observed and attributed to an increase in the photoabsorption effect by fullerene and the cooperative effect of the CdSe. The repeatability of photocatalytic activity was also tested in order to investigate the stability of C60 and CdS-C60/TiO2 composites. PMID:23618055

2013-01-01

380

Behavioral Masking and cFos Responses to Light in Day- and Night-Active Grass Rats.  

PubMed

Light not only entrains the circadian system but also has acute effects on physiology and behavior, a phenomenon known as masking. Behavioral masking responses to bright light differ in diurnal and nocturnal species, such that light increases arousal in the former and decreases it in the latter. Comparisons made within a species that displays both diurnal and nocturnal patterns of behavior may provide insight into how masking differs between chronotypes and the association between mechanisms controlling masking and the circadian drive for activity. Nile grass rats (Arvicanthis niloticus) provide a useful model for studying such issues because when these animals are housed with running wheels, some run primarily during day, while others run at night. Here we compared behavioral masking responses to 2-h pulses of light and darkness given across a 12:12 light/dark cycle in day-active (DA) and night-active (NA) grass rats. Both wheel-running activity (WRA) and general activity (GA) were monitored. Light pulses at night tended to increase both WRA and GA overall in the DA grass rats, while in NA grass rats, light pulses significantly reduced WRA but had no effect on GA. Dark pulses during the day tended to decrease both WRA and GA in the DA grass rats, while in the NA grass rats, they tended to increase WRA in the early day but had no effect on GA overall. Next, we measured cFos expression within 2 brain areas potentially involved in masking, the intergeniculate leaflet (IGL) and the olivary pretectal area (OPT), of DA and NA grass rats either sacrificed on a control night or after a 1-h light pulse at ZT14. In DA grass rats, light at ZT14 induced cFos in the IGL and OPT, whereas in NA grass rats, cFos levels in both structures were high at ZT14 and were not altered by a 1-h light pulse. Overall, these results suggest that masking responses to light and darkness are dependent on the chronotype of the individual and that the responsiveness of the IGL and OPT to light may depend on or contribute to the behavioral response of these animals. PMID:24916392

Langel, Jennifer; Yan, Lily; Nunez, Antonio A; Smale, Laura

2014-06-10

381

PERIOD CHANGES AND FOUR-COLOR LIGHT CURVES OF THE ACTIVE OVERCONTACT BINARY V396 MONOCEROTIS  

SciTech Connect

This paper analyzes the first obtained four-color light curves of V396 Mon using the 2003 version of the W-D code. It is confirmed that V396 Mon is a shallow W-type contact binary system with a mass ratio q = 2.554({+-}0.004) and a degree of contact factor f = 18.9%({+-}1.2%). A period investigation based on all available data shows that the period of the system includes a long-term decrease (dP/dt = -8.57 x 10{sup -8} days yr{sup -1}) and an oscillation (A{sub 3} = 0.0160 day, T{sub 3} = 42.4 yr). They are caused by angular momentum loss and light-time effect, respectively. The suspect third body is possibly a small M-type star (about 0.31 solar mass). Though some observations indicate that this system has strong magnetic activity, by our analysis we found that the Applegate mechanism cannot explain the periodic changes. This binary is an especially important system according to Qian's statistics of contact binaries as its mass ratio lies near the proposed pivot point about which the physical structure of contact binaries supposedly oscillates.

Liu, L.; Qian, S.-B.; Liao, W.-P.; He, J.-J.; Zhu, L.-Y.; Li, L.-J.; Zhao, E.-G., E-mail: creator_ll.student@sina.com, E-mail: LiuL@ynao.ac.cn [National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, P.O. Box 110, 650011 Kunming (China)

2011-02-15

382

Crystal structure of plant light-harvesting complex shows the active, energy-transmitting state.  

PubMed

Plants dissipate excess excitation energy as heat by non-photochemical quenching (NPQ). NPQ has been thought to resemble in vitro aggregation quenching of the major antenna complex, light harvesting complex of photosystem II (LHC-II). Both processes are widely believed to involve a conformational change that creates a quenching centre of two neighbouring pigments within the complex. Using recombinant LHC-II lacking the pigments implicated in quenching, we show that they have no particular role. Single crystals of LHC-II emit strong, orientation-dependent fluorescence with an emission maximum at 680 nm. The average lifetime of the main 680 nm crystal emission at 100 K is 1.31 ns, but only 0.39 ns for LHC-II aggregates under identical conditions. The strong emission and comparatively long fluorescence lifetimes of single LHC-II crystals indicate that the complex is unquenched, and that therefore the crystal structure shows the active, energy-transmitting state of LHC-II. We conclude that quenching of excitation energy in the light-harvesting antenna is due to the molecular interaction with external pigments in vitro or other pigment-protein complexes such as PsbS in vivo, and does not require a conformational change within the complex. PMID:19131972

Barros, Tiago; Royant, Antoine; Standfuss, Jörg; Dreuw, Andreas; Kühlbrandt, Werner

2009-02-01

383

Highly active WO3-Ag-ZnO photocatalyst driven by day light illumination  

NASA Astrophysics Data System (ADS)

The WO3 loaded Ag-ZnO (WO3-Ag-ZnO) was successfully synthesized by precipitation-decomposition method. The catalyst was characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) images, energy dispersive spectrum (EDS), transmission electron microscope (TEM), diffuse reflectance spectra (DRS), photoluminescence spectra (PL), cyclic voltammetry (CV) and BET surface area measurements. The photocatalytic activity of WO3-Ag-ZnO was investigated for the degradation of Naphthol Blue Black (NBB) in aqueous solution using solar light. WO3-Ag-ZnO is found to be more efficient than Ag-ZnO, WO3-ZnO, Ag-WO3, WO3, commercial ZnO, bare ZnO, TiO2-P25 and TiO2 (Merck) at pH 9 for the mineralization of NBB dye. The effects of operational parameters such as the amount of photocatalyst, dye concentration, initial pH on photo mineralization of NBB dye have been analyzed. The mineralization of NBB has been confirmed by Chemical Oxygen Demand (COD) measurements. A degradation mechanism is proposed for the degradation of NBB under solar light. This catalyst is found to be reusable.

Subash, B.; Krishnakumar, B.; Sreedhar, B.; Swaminathan, M.; Shanthi, M.

2013-02-01

384

Voltage Drop Compensation Method for Active Matrix Organic Light Emitting Diode Displays  

NASA Astrophysics Data System (ADS)

In this paper, the conventional voltage drop compensation methods are reviewed and the novel design and driving scheme, the advanced power de-coupled (aPDC) driving method, is proposed to effectively compensate the voltage IR drop of active matrix light emitting diode (AMOLED) displays. The advanced PDC driving scheme can be applied to general AMOLED pixel circuits that have been developed with only minor modification or without requiring modification in pixel circuit. A 14-in. AMOLED panel with the aPDC driving scheme was fabricated. Long range uniformity (LRU) of the 14-in. AMOLED panel was improved from 43% without the aPDC driving scheme, to over 87% at the same brightness by using the scheme and the layout complexity of the panel with new design scheme is less than that of the panel with the conventional design scheme.

Choi, Sang-moo; Ryu, Do-hyung; Kim, Keum-nam; Choi, Jae-beom; Kim, Byung-hee; Berkeley, Brian

2011-03-01

385

Correlation Analysis of Optical and Radio Light Curves for a Large Sample of Active Galactic Nuclei  

NASA Astrophysics Data System (ADS)

The Rosemary Hill Observatory has accumulated internally consistent light curves extending over as much as 26 years for a large sample of active galactic nuclei. Forty-six of these optical records have been compared with similar radio records from the University of Michigan Radio Astronomy Observatory and the Algonquin Radio Observatory. For 18 objects, pairs of records were sufficiently long and unconfused to allow reliable application of the Discrete Correlation Function analysis; this group included 8 BL Lacertids, 8 quasars, and 2 Seyfert galaxies. Nine of the 18 sources showed positive radio-optical correlations, with the radio events lagging the optical by intervals ranging from 0 to 14 months. Consistent with the relativistic beaming model of the BL Lacertids, the group displaying correlations was dominated by this type of object.

Clements, S. D.; Smith, A. G.; Aller, H. D.; Aller, M. F.

1995-08-01

386

Active imaging systems to see through adverse conditions: Light-scattering based models and experimental validation  

NASA Astrophysics Data System (ADS)

Onera, the French aerospace lab, develops and models active imaging systems to understand the relevant physical phenomena affecting these systems performance. As a consequence, efforts have been done on the propagation of a pulse through the atmosphere and on target geometries and surface properties. These imaging systems must operate at night in all ambient illumination and weather conditions in order to perform strategic surveillance for various worldwide operations. We have implemented codes for 2D and 3D laser imaging systems. As we aim to image a scene in the presence of rain, snow, fog or haze, we introduce such light-scattering effects in our numerical models and compare simulated images with measurements provided by commercial laser scanners.

Riviere, Nicolas; Ceolato, Romain; Hespel, Laurent

2014-10-01

387

AgI/TiO2 nanobelts monolithic catalyst with enhanced visible light photocatalytic activity.  

PubMed

AgI nanoparticles (NPs) have been decorated on the TiO2 nanobelts (NBs) immobilized on a metal Ti substrate by a simple impregnating-precipitation method. The as-achieved AgI/TiO2 monolithic catalyst exhibits a high and stable visible photocatalytic activity toward acid orange II (AO-II) degradation, which is attributed to the suitable energy band match of AgI NPs and TiO2 NBs, leading to the efficient transfer of photo-generated electrons. In addition, it was found that O2(-) radicals and h(+) are the main reactive species for the degradation of AO-II under visible light irradiation. A reasonable photocatalytic mechanism of AgI/TiO2 photocatalyst toward AO-II degradation was discussed. This monolithic catalyst provides an advantage over the drawback encountered with powder suspension. PMID:25463235

Yi, Junhui; Huang, Lingling; Wang, Hongjuan; Yu, Hao; Peng, Feng

2015-03-01

388

Light-activated amino acid transport in Halobacterium halobium envelope vesicles  

NASA Technical Reports Server (NTRS)

Vesicles prepared from Halobacterium halobium cell envelopes accumulate amino acids in response to light-induced electrical and chemical gradients. Nineteen of 20 commonly occurring amino acids have been shown to be actively accumulated by these vesicles in response to illumination or in response to an artificially created Na+ gradient. On the basis of shared common carriers the transport systems can be divided into eight classes, each responsible for the transport of one or several amino acids: arginine, lysine, histidine; asparagine, glutamine; alanine, glycine, threonine, serine; leucine, valine, isoleucine, methionine; phenylalanine, tyrosine, tryptophan; aspartate; glutamate; proline. Available evidence suggests that these carriers are symmetrical in that amino acids can be transported equally well in both directions across the vesicle membranes. A tentative working model to account for these observations is presented.

Macdonald, R. E.; Lanyi, J. K.

1977-01-01

389

Effect of a floating electrode on a plasma jet  

SciTech Connect

Two kinds of floating electrode, floating dielectric barrier covered electrode (FDBCE) and floating pin electrode (FPE), which can enhance the performance of plasma jet are reported. The intense discharge between the floating electrode and power electrode decreased the voltage to trigger the plasma jet substantially. The transition of plasma bullet from ring shape to disk shape in the high helium concentration region happened when the floating electrode was totally inside the powered ring electrode. The enhanced electric field between propagating plasma bullet and ground electrode is the reason for this transition. The double plasma bullets happened when part of the FDBCE was outside the powered ring electrode, which is attributed to the structure and surface charge of FDBCE. As part of the FPE was outside the powered ring electrode, the return stroke resulted in a single intensified plasma channel between FPE and ground electrode.

Hu, J. T.; Wang, J. G.; Liu, X. Y.; Liu, D. W.; Lu, X. P. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, WuHan, HuBei 430074 (China)] [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, WuHan, HuBei 430074 (China); Shi, J. J. [College of Science, Donghua University, Shanghai 201620 (China)] [College of Science, Donghua University, Shanghai 201620 (China); Ostrikov, K. [Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, P. O. Box 218, Lindfield, New South Wales 2070 (Australia)] [Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, P. O. Box 218, Lindfield, New South Wales 2070 (Australia)

2013-08-15

390

Hydroelastic responses of pontoon type very large floating offshore structure  

SciTech Connect

The authors developed the estimating method of the hydroelastic response of a very large pontoon type floating structure. In this method, the pressure distribution method with shallow draft assumption was used to obtain the hydrodynamic forces considering the elastic motion of a floating body. The elastic responses of very large floating structure were estimated by using 1-D beam modeling. On the other hand, to observe the elastic response of a large pontoon type structure they carried out experiments in head sea and head-beam sea conditions. The experimental model was an elastic model of pontoon type large floating body. To validate numerical estimation method the authors compared the numerical results with experimental results. From these results, they found good agreement and confirmed the accuracy of this numerical estimation method of the hydroelasticity of a very large pontoon type floating structure.

Haeda, Hisaaki; Miyajima, Shyogo [Univ. of Tokyo (Japan). Inst. of Industrial Science; Masuda, Koich; Ikoma, Tomoki [Nihon Univ., Funabashi, Chiba (Japan)

1996-12-31

391

Two-state model of light induced activation and thermal bleaching of photochromic glasses: theory and experiments  

SciTech Connect

The behavior of photochromic glasses during activation and bleaching is investigated. A two-state phenomenological model describing light-induced activation (darkening) and thermal bleaching is presented. The proposed model is based on first-order kinetics. We demonstrate that the time behavior in the activation process (acting simultaneously with the thermal fading) can be characterized by two relaxation times that depend on the intensity of the activating light. These characteristic times are lower than the decay times of the pure thermal bleaching process. We study the temporal evolution of the glass optical density and its dependence on the activating intensity. We also present a series of activation and bleaching experiments that validate the proposed model. Our approach may be used to gain more insight into the transmittance behavior of photosensitive glasses, which could be potentially relevant in a broad range of applications, e.g., real-time holography and reconfigurable optical memories.

Ferrari, Jose A.; Perciante, Cesar D

2008-07-10

392

Memory: graphene-graphene oxide floating gate transistor memory (small 3/2015).  

PubMed

A novel, transparent, flexible graphene channel floating-gate transistor memory (FGTM) device is developed by J. H. Cho and co-workers, who combine a single-layer graphene active channel with graphene oxide (GO) charge trap elements. On page 311, the application of positively charged GO (GO-NH3 (+) ) and precise control over n-doping in the graphene channel dramatically enhance the electrical performance and mechanical stability of the memory device. PMID:25641610

Jang, Sukjae; Hwang, Euyheon; Lee, Jung Heon; Park, Ho Seok; Cho, Jeong Ho

2015-01-01

393

Floating marine debris in coastal waters of the SE-Pacific (Chile)  

Microsoft Academic Search

Herein we report on the abundance and composition of floating marine debris (FMD) in coastal waters of the SE-Pacific (off the Chilean coast) during the austral summer 2002. The observed FMD consisted mainly of plastic material (86.9%). Densities of FMD were highest between 20°S and 40°S, corresponding to the main concentrations of human population and activities. Low densities of FMD

M. Thiel; I. Hinojosa; N. Vásquez; E. Macaya

2003-01-01

394

Thermodynamic and kinetic investigation of high-temperature interactions between float glass and tin  

NASA Astrophysics Data System (ADS)

The primary goal of this research was to understand the role of iron and sulfur in glass on tin penetration during the float process, and to describe the factors controlling glass/tin interdiffusion reaction(s). Tin penetration increased with increasing iron concentration, and with increasing sulfur concentration at fixed iron levels. The tin depth profile in the high-iron glasses, in general, exhibited a 'bump' at approximately half the penetration depth which was correlated with the depletion depth of iron and sulfur. A miniature float bath apparatus was used to systematically investigate the effects of time, temperature, glass composition and redox, and tin bath chemistry on the nature of tin penetration during the float process. Tin depth profiles similar to those measured in commercial float glass were reproduced in the lab-scale float apparatus. As temperature increased, the tin concentration in the outer 1mum decreased, yet accumulation at greater depths (2-120mum) occurred. Increasing the iron concentration in the tin bath reduced the overall tin penetration and iron depletion in the high iron glasses at higher temperatures. At lower temperatures, the effect of iron doping in the tin was less noticeable. Iron penetration from the tin bath into the low iron glasses was observed at lower temperatures. High levels of oxygen in the tin bath resulted in higher tin penetration, but the penetration depth was not effected. The thermodynamic calculations of high temperature phase equilibria revealed that regardless of the glass composition or iron redox, an oxygen activity differential existed between the glass and tin bath which spanned up to 15 orders of magnitude. This oxygen activity gradient was fundamental to the formation of the bump observed in the tin penetration profiles of glasses floated on the lab tin bath. A simple diffusion model was created to generate tin penetration profiles which were similar to the glass profiles. Assuming the oxygen activity gradient followed the iron depletion profiles in the glasses, the formation of the bump in the tin penetration profiles was found to be the result of an accumulation of Snsp{4+} at the point of tin oxidation.

Paulson, Thomas Edward

395

Low Power, Red, Green and Blue Carbon Nanotube Enabled Vertical Organic Light Emitting Transistors for Active Matrix OLED Displays  

SciTech Connect

Organic semiconductors are potential alternatives to polycrystalline silicon as the semiconductor used in the backplane of active matrix organic light emitting diode displays. Demonstrated here is a light-emitting transistor with an organic channel, operating with low power dissipation at low voltage, and high aperture ratio, in three colors: red, green and blue. The single-wall carbon nanotube network source electrode is responsible for the high level of performance demonstrated. A major benefit enabled by this architecture is the integration of the drive transistor, storage capacitor and light emitter into a single device. Performance comparable to commercialized polycrystalline-silicon TFT driven OLEDs is demonstrated.

McCarthy, M. A. [University of Florida, Gainesville; Liu, B. [University of Florida, Gainesville; Donoghue, E. P. [University of Florida, Gainesville; Kravchenko, Ivan I [ORNL; Kim, D. Y. [University of Florida, Gainesville; So, Franky [University of Florida, Gainesville; Rinzler, A. G. [University of Florida, Gainesville

2011-01-01

396

Short term changes in methanol emission and pectin methylesterase activity are not directly affected by light in Lycopersicon esculentum  

NASA Astrophysics Data System (ADS)

Plants are an important source of atmospheric methanol (MeOH), the second most abundant organic gas after methane. Factors regulating phytogenic MeOH production are not well constrained in current MeOH emission models. Previous studies have indicated that light may have a direct influence on MeOH production. As light is known to regulate cell wall expansion, it was predicted that light would stimulate MeOH production through the pectin methylesterase (PME) pathway. MeOH emissions normalized for stomatal conductance (gs) did not, however, increase with light over short time scales (20-30 min). After experimentally controlling for gs and temperature, no light activation of PME activity or MeOH emission was observed. The results clearly demonstrate that light does not directly influence short-term changes in MeOH production and emission. Our data suggest that substrate limitation may be important in regulating MeOH production over short time scales. Future investigation of the long-term impacts of light on MeOH production may increase understanding of MeOH emission dynamics at the seasonal time scale.

Oikawa, P. Y.; Li, L.; Timko, M. P.; Mak, J. E.; Lerdau, M. T.

2011-01-01

397

Short term changes in methanol emission and pectin methylesterase activity are not directly affected by light in Lycopersicon esculentum  

NASA Astrophysics Data System (ADS)

Plants are an important source of atmospheric methanol (MeOH), the second most abundant organic gas after methane. Factors regulating phytogenic MeOH production are not well constrained in current MeOH emission models. Previous studies have indicated that light may have a direct influence on MeOH production. As light is known to regulate cell wall expansion, it was predicted that light would stimulate MeOH production through the pectin methylesterase (PME) pathway. MeOH emissions normalized for stomatal conductance (gs) did not, however, increase with light over short time scales (20-30 min). After experimentally controlling for gs and temperature, no light activation of PME activity or MeOH emission was observed. The results clearly demonstrate that light does not directly influence short-term changes in MeOH production and emission. Our data suggest that substrate limitation may be important in regulating MeOH production over short time scales. Future investigation of the long-term impacts of light on MeOH production may increase understanding of MeOH emission dynamics at the seasonal time scale.

Oikawa, P. Y.; Li, L.; Timko, M. P.; Mak, J. E.; Lerdau, M. T.

2011-04-01

398

Floating-zone and floating-solution-zone growth of GaSb under microgravity  

Microsoft Academic Search

Three GaSb single crystals have been successfully grown under microgravity on Spacehab-4 during the STS-77 Space Shuttle flight. Two Te-doped crystals with 16mm diameter and lengths of 31.5 and 18mm, respectively, were grown by the floating-zone method. From the transition of striated to striation-free material it was possible to determine the critical Marangoni number for the onset of time-dependent thermocapillary

A. Cröll; Th Kaiser; M Schweizer; A. N Danilewsky; S Lauer; A Tegetmeier; K. W Benz

1998-01-01

399

Role of Visible Light-Activated Photocatalyst on the Reduction of Anthrax Spore-Induced Mortality in Mice  

PubMed Central

Background Photocatalysis of titanium dioxide (TiO2) substrates is primarily induced by ultraviolet light irradiation. Anion-doped TiO2 substrates were shown to exhibit photocatalytic activities under visible-light illumination, relative environmentally-friendly materials. Their anti-spore activity against Bacillus anthracis, however, remains to be investigated. We evaluated these visible-light activated photocatalysts on the reduction of anthrax spore-induced pathogenesis. Methodology/Principal Findings Standard plating method was used to determine the inactivation of anthrax spore by visible light-induced photocatalysis. Mouse models were further employed to investigate the suppressive effects of the photocatalysis on anthrax toxin- and spore-mediated mortality. We found that anti-spore activities of visible light illuminated nitrogen- or carbon-doped titania thin films significantly reduced viability of anthrax spores. Even though the spore-killing efficiency is only approximately 25%, our data indicate that spores from photocatalyzed groups but not untreated groups have a less survival rate after macrophage clearance. In addition, the photocatalysis could directly inactivate lethal toxin, the major virulence factor of B. anthracis. In agreement with these results, we found that the photocatalyzed spores have tenfold less potency to induce mortality in mice. These data suggest that the photocatalysis might injury the spores through inactivating spore components. Conclusion/Significance Photocatalysis induced injuries of the spores might be more important than direct killing of spores to reduce pathogenicity in the host. PMID:19132100

Huang, Hsin-Hsien; Wong, Ming-Show; Lin, Hung-Chi; Chang, Hsin-Hou

2009-01-01

400

Controlled synthesis and visible light photocatalytic activity of Bi12GeO20 uniform microcrystals  

PubMed Central

We successfully synthesized uniform Bi12GeO20 microspheres and microtetrahedrons enclosed by four {111} facets using a controlled hydrothermal method for the first time. The photocatalytic activity of these regular-shaped products was further investigated by the degradation of RhB and gaseous formaldehyde under visible light irradiation (?>420?nm). The Bi12GeO20 microtetrahedrons (s) exhibited enhanced photocatalytic activity and stability which is closely related to the high capacity of exposed {111} facets for uptake of O2. The formation mechanism studies indicate that the Bi12GeO20 seeds were directed to grow into truncated microcubes, truncated microtetrahedrons, and then microtetrahedrons when the NaOH concentration was 5?M. The same batch of seeds only evolved into microspheres when the NaOH concentration was switched to 3?M. The difference in Bi12GeO20 morphology could be attributed to the rates of both crystal nucleation and crystal growth. PMID:25199641

Wan, Zhen; Zhang, Gaoke

2014-01-01

401

Controlled synthesis and visible light photocatalytic activity of Bi12GeO20 uniform microcrystals.  

PubMed

We successfully synthesized uniform Bi12GeO20 microspheres and microtetrahedrons enclosed by four {111} facets using a controlled hydrothermal method for the first time. The photocatalytic activity of these regular-shaped products was further investigated by the degradation of RhB and gaseous formaldehyde under visible light irradiation (?>420?nm). The Bi12GeO20 microtetrahedrons (s) exhibited enhanced photocatalytic activity and stability which is closely related to the high capacity of exposed {111} facets for uptake of O2. The formation mechanism studies indicate that the Bi12GeO20 seeds were directed to grow into truncated microcubes, truncated microtetrahedrons, and then microtetrahedrons when the NaOH concentration was 5?M. The same batch of seeds only evolved into microspheres when the NaOH concentration was switched to 3?M. The difference in Bi12GeO20 morphology could be attributed to the rates of both crystal nucleation and crystal growth. PMID:25199641

Wan, Zhen; Zhang, Gaoke

2014-01-01

402

Controlled synthesis and visible light photocatalytic activity of Bi12GeO20 uniform microcrystals  

NASA Astrophysics Data System (ADS)

We successfully synthesized uniform Bi12GeO20 microspheres and microtetrahedrons enclosed by four {111} facets using a controlled hydrothermal method for the first time. The photocatalytic activity of these regular-shaped products was further investigated by the degradation of RhB and gaseous formaldehyde under visible light irradiation (?>420 nm). The Bi12GeO20 microtetrahedrons (s) exhibited enhanced photocatalytic activity and stability which is closely related to the high capacity of exposed {111} facets for uptake of O2. The formation mechanism studies indicate that the Bi12GeO20 seeds were directed to grow into truncated microcubes, truncated microtetrahedrons, and then microtetrahedrons when the NaOH concentration was 5 M. The same batch of seeds only evolved into microspheres when the NaOH concentration was switched to 3 M. The difference in Bi12GeO20 morphology could be attributed to the rates of both crystal nucleation and crystal growth.

Wan, Zhen; Zhang, Gaoke

2014-09-01

403

Understanding the superior photocatalytic activity of noble metals modified titania under UV and visible light irradiation.  

PubMed

Although TiO2 is one of the most efficient photocatalysts, with the highest stability and the lowest cost, there are drawbacks that hinder its practical applications like its wide band gap and high recombination rate of the charge carriers. Consequently, many efforts were directed toward enhancing the photocatalytic activity of TiO2 and extending its response to the visible region. To head off these attempts, modification of TiO2 with noble metal nanoparticles (NMNPs) received considerable attention due to their role in accelerating the transfer of photoexcited electrons from TiO2 and also due to the surface plasmon resonance which induces the photocatalytic activity of TiO2 under visible light irradiation. This insightful perspective is devoted to the vital role of TiO2 photocatalysis and its drawbacks that urged researchers to find solutions such as modification with NMNPs. In a coherent context, we discussed here the characteristics which qualify NMNPs to possess a great enhancement effect for TiO2 photocatalysis. Also we tried to understand the reasons behind this effect by means of photoluminescence (PL) and electron paramagnetic resonance (EPR) spectra, and Density Functional Theory (DFT) calculations. Then the mechanism of action of NMNPs upon deposition on TiO2 is presented. Finally we introduced a survey of the behaviour of these noble metal NPs on TiO2 based on the particle size and the loading amount. PMID:24554000

Bumajdad, Ali; Madkour, Metwally

2014-04-28

404

UFO: "Unidentified" Floating Object Driven by Thermocapillarity  

E-print Network

In this fluid dynamics video, we show thermocapillary actuation of a binary drop of water and heptanol where the binary drop in motion takes on a UFO-like shape. On a parylene-coated silicon surface subjected to a linear temperature gradient, a pure heptanol droplet quickly moves to the cold side by the Marangoni stress, while a pure water droplet remains stuck due to a large contact angle hysteresis. When the water droplet was encapsulated by a thin layer of heptanol and thermally actuated, the binary droplet takes on a peculiar shape resembling an UFO, i.e. an "unidentified" floating object as the mechanism is not yet completely understood. Our finding suggests that pure liquid droplets (e.g. aqueous solutions) that are not conducive to thermocapillary actuation can be made so by encapsulating them with another judiciously chosen liquid (e.g. heptanol).

Zhao, Yuejun

2010-01-01

405

Laminar mixing in a small floating zone  

NASA Technical Reports Server (NTRS)

The relationship between the flow and solute fields during steady mass transfer of a dilute component is analyzed for multi-cellular rotating flows in the floating zone process of semiconductor growth. When the recirculating flows are weak in relation to the rate of crystal growth, a closed-form solution clearly shows the link between the convection pattern in the melt and the solute distribution across the surface of the growing solid. In the limit of strong convection, finite element calculations demonstrate the tendency of the composition to become uniform over the majority of the melt. The solute segregation in the product crystal is greatest when the recirculating motion is comparable to the rate of crystal growth, and points to the danger in attempting to grow compositionally uniform materials from a nearly convectionless melt.

Harriott, George M.

1987-01-01

406

Synthesis and photocatalytic activity of mesoporous cerium doped TiO{sub 2} as visible light sensitive photocatalyst  

SciTech Connect

Graphical abstract: Cerium doped titania having optimum 5 wt% of cerium can decompose methylene blue and reduce selenium (IV) efficiently under visible light. Highlights: Black-Right-Pointing-Pointer Effect of cerium doping on the surface properties and visible light mediated photocatalytic reaction is studied. Black-Right-Pointing-Pointer Cerium doping increases the anatase phase stability, surface area (up to 137 m{sup 2}/g) and visible light absorption. Black-Right-Pointing-Pointer Importance of Ce{sup 3+}/Ce{sup 4+}, oxygen vacancy, surface area and crystallinity is correlated with improved catalytic activity. Black-Right-Pointing-Pointer Material with 5 wt% Ce is found to be most active photocatalyst for methylene blue decomposition and Se (IV) reduction. -- Abstract: Cerium doped titania materials were synthesized varying the cerium concentration from 0 to 10 wt%. Materials are characterised by XRD, TEM, XPS and N{sub 2} adsorption desorption method. Surface area and visible light absorption substantially increases and crystallite size decreases with the increasing cerium content. Cerium doping stabilizes the anatase phase and surface area even at 600 Degree-Sign C calcination. Photocatalytic activity towards methylene blue decomposition and selenium (IV) reduction is found to increase with the cerium content up to 5 wt% and then decreases. Materials calcined at 600 Degree-Sign C shows better activity than that calcined at 400 Degree-Sign C, even though surface area decreases. Anatase crystallinity mostly decides the photocatalytic activity rather than only surface area. It can be concluded that the optimum visible light absorption and oxygen vacancy with 5% cerium doping enhances the photocatalytic activity. In addition photocatalytic performance is found to depend on the presence of Ce{sup 4+}/Ce{sup 3+} rather than only visible light absorption.

Aman, Noor [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India)] [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Satapathy, P.K. [PG Department of Chemistry, North Orissa University, Baripada 757003, Orissa (India)] [PG Department of Chemistry, North Orissa University, Baripada 757003, Orissa (India); Mishra, T., E-mail: drtmishra@yahoo.com [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Mahato, M. [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India)] [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Das, N.N. [PG Department of Chemistry, North Orissa University, Baripada 757003, Orissa (India)] [PG Department of Chemistry, North Orissa University, Baripada 757003, Orissa (India)

2012-02-15

407

Design and fabrication of active spectral filter with metal-insulator-metal structure for visible light communication  

NASA Astrophysics Data System (ADS)

Visible light communication with LED is an important ICT for the ubiquitous network society. However visible light communication has the speed limit in the conventional blinking LED method. Therefore an active spectral filter would be useful in order to input information signals onto the LED spectrum. Plasmonic spectral filter based on a metalinsulator- metal (MIM) structure is one of the candidates of such active filter. We will explain our progress of fabrication of the MIM structures with the vacuum deposition technique and compare their absorption properties with the theoretical prediction.

Murai, Kensuke; Oshikane, Yasushi; Higashi, Takaya; Yamamoto, Fumihiko; Nakano, Motohiro; Inoue, Haruyuki

2013-02-01

408

Characterization and improved solar light activity of vanadium doped TiO2/diatomite hybrid catalysts.  

PubMed

V-doped TiO2/diatomite composite photocatalysts with different vanadium concentrations were synthesized by a modified sol-gel method. The diatomite was responsible for the well dispersion of TiO2 nanoparticles on the matrix and consequently inhibited the agglomeration. V-TiO2/diatomite hybrids showed red shift in TiO2 absorption edge with enhanced absorption intensity. Most importantly, the dopant energy levels were formed in the TiO2 bandgap due to V(4+) ions substituted to Ti(4+) sites. The 0.5% V-TiO2/diatomite photocatalyst displayed narrower bandgap (2.95eV) compared to undoped sample (3.13eV) and other doped samples (3.05eV) with higher doping concentration. The photocatalytic activities of V doped TiO2/diatomite samples for the degradation of Rhodamine B under stimulated solar light illumination were significantly improved compared with the undoped sample. In our case, V(4+) ions incorporated in TiO2 lattice were responsible for increased visible-light absorption and electron transfer to oxygen molecules adsorbed on the surface of TiO2 to produce superoxide radicals O2(-), while V(5+) species presented on the surface of TiO2 particles in the form of V2O5 contributed to e(-)-h(+) separation. In addition, due to the combination of diatomite as support, this hybrid photocatalyst could be separated from solution quickly by natural settlement and exhibited good reusability. PMID:25497036

Wang, Bin; Zhang, Guangxin; Leng, Xue; Sun, Zhiming; Zheng, Shuilin

2015-03-21

409

Investigation of the peak action wavelength of light-activated gene transduction (LAGT)  

PubMed Central

Light-activated gene transduction (LAGT) is an approach to localize gene therapy via preactivation of cells with UV light, which facilitates transduction by recombinant adeno-associated virus vectors. Prior studies demonstrated that UVC induces LAGT secondary to pyrimidine dimer formation, while UVA induces LAGT secondary to reactive oxygen species (ROS) generation. However, the empirical UVB boundary of these UV effects is unknown. Thus, we aimed to define the action spectra for UV-induced LAGT independent of DNA damage, and determine an optimal wavelength to maximize safety and efficacy. Results: UV at 288, 311 and 320nm produced significant dose-dependent LAGT effects, of which the maximum (800-fold) was observed with 4kJ/m2 at 311nm. Consistent with its robust cytotoxicity, 288nm produced significantly high levels of DNA damage at all doses tested, while 311, 320 and 330nm did not generate pyrimidine dimers and produced low levels of DNA damage detected by comet assay. While 288nm failed to induce ROS, the other wavelengths were effective, with the maximum (10-fold) effect observed with 30 kJ/m2 at 311nm. An in vivo pilot study assessing 311nm-induced LAGT of rabbit articular chondrocytes demonstrated a significant 6.6-fold (p<0.05) increase in transduction with insignificant cytotoxicity. Conclusion: 311nm was found to be the optimal wavelength for LAGT based on its superior efficacy at the peak dose, and its broad safety range that is remarkably wider than the other UV wavelengths tested. PMID:21490685

Myakishev-Rempel, Max; Kuper, Jerry; Mintz, Benjamin; Hutchinson, Sara; Voris, Jay; Zavislan, Katrina; Offley, Sarah; Nardia, Frances Barg; Yaseen, Zaneb; Yen, Tony; Zavislan, James; Maloney, Michael D.; Schwarz, Edward M.

2011-01-01

410

Defining the IEEE-854 floating-point standard in PVS  

NASA Technical Reports Server (NTRS)

A significant portion of the ANSI/IEEE-854 Standard for Radix-Independent Floating-Point Arithmetic is defined in PVS (Prototype Verification System). Since IEEE-854 is a generalization of the ANSI/IEEE-754 Standard for Binary Floating-Point Arithmetic, the definition of IEEE-854 in PVS also formally defines much of IEEE-754. This collection of PVS theories provides a basis for machine checked verification of floating-point systems. This formal definition illustrates that formal specification techniques are sufficiently advanced that is is reasonable to consider their use in the development of future standards.

Miner, Paul S.

1995-01-01

411

Formulation and in vitro Evaluation of Floating Capsules of Theophylline  

PubMed Central

Sustained release floating capsules for theophylline were fabricated using drug:polymer ratio of 30:70. The hydrocolloids were used in different proportions and four formulations were prepared. These formulations were optimized on the basis of buoyancy, matrix integrity, duration of floating and in vitro drug release. All the four formulations showed good buoyancy and matrix integrity. The duration of floating was more than 12 h for all formulations. In vitro drug release study of these formulations indicated controlled release of theophylline and about 76 percent drug was released at the end of 12 h. PMID:20046717

Bhise, S. B.; Aloorkar, N. H.

2008-01-01

412

Radiation Issues and Applications of Floating Gate Memories  

NASA Technical Reports Server (NTRS)

The radiation effects that affect various systems that comprise floating gate memories are presented. The wear-out degradation results of unirradiated flash memories are compared to irradiated flash memories. The procedure analyzes the failure to write and erase caused by wear-out and degradation of internal charge pump circuits. A method is described for characterizing the radiation effects of the floating gate itself. The rate dependence, stopping power dependence, SEU susceptibility and applications of floating gate in radiation environment are presented. The ramifications for dosimetry and cell failure are discussed as well as for the long term use aspects of non-volatile memories.

Scheick, L. Z.; Nguyen, D. N.

2000-01-01

413

Laser-diode-heated floating zone (LDFZ) method appropriate to crystal growth of incongruently melting materials  

NASA Astrophysics Data System (ADS)

We have developed a laser-diode-heated floating zone (LDFZ) method, in order to improve the broad and inhomogeneous light focusing in the conventional lamp-heated floating zone method, which often causes difficulties in the crystal growth especially for the incongruently melting materials. We have simulated the light focusing properties of the LDFZ method to make the whole of the molten zone irradiated with concentrated and homogeneous laser lights. We have designed and assembled an LDFZ furnace, and have demonstrated how it works through actual crystal growth. The method is applicable to various kinds of materials, and enables stable and reproducible crystal growth even for the incongruently melting materials. We have succeeded in the crystal growth of representatives of the incongruently melting materials such as BiFeO3 and (La,Ba)2CuO4, which were believed to be difficult to be grown by the conventional method. Tolerance to the decentering of samples and highly efficient heating are also established in the LDFZ method.

Ito, Toshimitsu; Ushiyama, Tomoharu; Yanagisawa, Yuji; Tomioka, Yasuhide; Shindo, Isamu; Yanase, Atsushi

2013-01-01

414

The difference between "giving a rose" and "giving a kiss": Sustained neural activity to the light verb construction.  

PubMed

We used event-related potentials (ERPs) to investigate the neurocognitive mechanisms associated with processing light verb constructions such as "give a kiss". These constructions consist of a semantically underspecified light verb ("give") and an event nominal that contributes most of the meaning and also activates an argument structure of its own ("kiss"). This creates a mismatch between the syntactic constituents and the semantic roles of a sentence. Native speakers read German verb-final sentences that contained light verb constructions (e.g., "Julius gave Anne a kiss"), non-light constructions (e.g., "Julius gave Anne a rose"), and semantically anomalous constructions (e.g., *"Julius gave Anne a conversation"). ERPs were measured at the critical verb, which appeared after all its arguments. Compared to non-light constructions, the light verb constructions evoked a widely distributed, frontally focused, sustained negative-going effect between 500 and 900 ms after verb onset. We interpret this effect as reflecting working memory costs associated with complex semantic processes that establish a shared argument structure in the light verb constructions. PMID:24910498

Wittenberg, Eva; Paczynski, Martin; Wiese, Heike; Jackendoff, Ray; Kuperberg, Gina

2014-05-01

415

Optimization and evaluation of clarithromycin floating tablets using experimental mixture design.  

PubMed

The purpose of the study was to prepare and evaluate clarithromycin (CLA) floating tablets using experimental mixture design for treatment of Helicobacter pylori provided by prolonged gastric residence time and controlled plasma level. Ten different formulations were generated based on different molecular weight of hypromellose (HPMC K100, K4M, K15M) by using simplex lattice design (a sub-class of mixture design) with Minitab 16 software. Sodium bicarbonate and anhydrous citric acid were used as gas generating agents. Tablets were prepared by wet granulation technique. All of the process variables were fixed. Results of cumulative drug release at 8th h (CDR 8th) were statistically analyzed to get optimized formulation (OF). Optimized formulation, which gave floating lag time lower than 15 s and total floating time more than 10 h, was analyzed and compared with target for CDR 8th (80%). A good agreement was shown between predicted and actual values of CDR 8th with a variation lower than 1%. The activity of clarithromycin contained optimizedformula against H. pylori were quantified using well diffusion agar assay. Diameters of inhibition zones vs. log10 clarithromycin concentrations were plotted in order to obtain a standard curve and clarithromycin activity. PMID:25272652

U?urlu, Timucin; Karaçiçek, U?ur; Rayaman, Erkan

2014-01-01

416

Optimization Studies on Compression Coated Floating-Pulsatile Drug Delivery of Bisoprolol  

PubMed Central

The purpose of the present work was to design and optimize compression coated floating pulsatile drug delivery systems of bisoprolol. Floating pulsatile concept was applied to increase the gastric residence of the dosage form having lag phase followed by a burst release. The prepared system consisted of two parts: a core tablet containing the active ingredient and an erodible outer shell with gas generating agent. The rapid release core tablet (RRCT) was prepared by using superdisintegrants with active ingredient. Press coating of optimized RRCT was done by polymer. A 32 full factorial design was used for optimization. The amount of Polyox WSR205 and Polyox WSR N12K was selected as independent variables. Lag period, drug release, and swelling index were selected as dependent variables. Floating pulsatile release formulation (FPRT) F13 at level 0 (55?mg) for Polyox WSR205 and level +1 (65?mg) for Polyox WSR N12K showed lag time of 4?h with >90% drug release. The data were statistically analyzed using ANOVA, and P < 0.05 was statistically significant. Release kinetics of the optimized formulation best fitted the zero order model. In vivo study confirms burst effect at 4?h in indicating the optimization of the dosage form. PMID:24367788

Jagdale, Swati C.; Bari, Nilesh A.; Kuchekar, Bhanudas S.; Chabukswar, Aniruddha R.

2013-01-01

417

Forecasting life: a study of activity cycles in low-mass stars: lessons from long-term stellar light curves.  

PubMed

Magnetic activity cycles are indirect traces of magnetic fields and can provide an insight on the nature and action of stellar dynamos and stellar magnetic activity. This, in turn, can determine local space weather and activity effects on stellar habitable zones. Using photometric monitoring of low-mass stars, we study the presence and properties of their magnetic activity cycles. We introduce long-term light curves of our sample stars, and discuss the properties of the observed trends, especially at spectral types where stars are fully convective (later than M3). PMID:22729352

Kafka, Stella

2012-06-01

418

Clearance of the heavy and light polypeptide chains of human tissue-type plasminogen activator in rats.  

PubMed Central

In order to assess which part of the tissue-type plasminogen activator (t-PA) molecule should be (genetically) modified to obtain more-slowly-clearing mutants, two-chain t-PA and its isolated heavy and light chains were radiolabelled and injected into rats. The vast majority of t-PA and the heavy chain disappeared from the blood circulation with half-lives of 2.3 and 1.0 min respectively. The clearance of the light chain was biphasic, owing to complex-formation with plasma proteinase inhibitors. The disappearance of di-isopropylphospho-light chain, which has a blocked active site, was nearly monophasic, with a half-life of 5.7 min. Organ distribution studies showed that hepatic clearance constituted the major pathway in all cases. These results strongly suggest that t-PA is recognized by the liver primarily through the heavy chain. PMID:3099771

Rijken, D C; Emeis, J J

1986-01-01

419

Silver Phosphate Based Plasmonic Photocatalyst: Highly Active Visible-Light Photocatalytic Property and Photosensitized Degradation of Pollutants  

NASA Astrophysics Data System (ADS)

A stable silver phosphate based plasmonic photocatalyst (Ag-Ag3PO4) was successfully fabricated, which can drive catalytic reaction under low-intensity visible light. The synthesized plasmonic photocatalyst shows high performance and stability on the photodegradation of RhB under visible-light irradiation, and represents obviously enhanced photocatalytic activity than the pure Ag3PO4 sample. The photosensitization process was carried out in the photodegradation of 2,4-DCP and RhB mixture, of which the photocatalyst shows the enhancement activity for 2,4-DCP while weaker for RhB. The investigation is likely to open up a new sight for the preparation of high efficient and stable plasmonic photocatalysts which utilizes visible light.

Lei, Yongqian; Wang, Guanhua; Guo, Pengran; Song, Huacan

2012-12-01

420

67P/Churyumov-Gerasimenko: start of activity and heliocentric light curve  

NASA Astrophysics Data System (ADS)

Comets are believed to be widely unmodified remnants from the formation of the solar system; their study can give important insights into the conditions prevailing at the time of the planetary system formation. After the success of the Giotto mission to comet 1P/Halley, the European Space Agency (ESA) approved in the early nineties a new space mission with a comet as main target: Rosetta, which will rendezvous with come 67P/Churyumov-Gerasimenko (67P/C-G) in 2014. 67P/C-G is a Jupiter family comet with orbital period of 6.56 years. Due to repeated encounters with Jupiter, the orbital evolution of 67P/C-G is chaotic. The last encounter in February 1959 occurred at a distance of only 0.0518 AU and produced drastic changes in perihelion distance, eccentricity, inclination, orbital period and possibly led to its discovery in 1969. After 67P/C-G was selected as target comet of Rosetta mission, observational campaigns and theoretical investigations were performed in order to establish a detailed portrait of 67P/C-G in preparation of the rendezvous with the spacecraft ([1], [2], [3], [4]). Here we present ground-based observations of 67P/CG obtained between July 2007 and March 2008 at ESO VLT using the FORS2 instrument. The comet was moving inbound, from 4.6 AU to 3.4 AU. The orbital arc covered by our observation is the same where 67P/C-G will be in 2014 when the rendezvous with the Rosetta spacecraft will take place, thus of highly interest for mission planning. Since the comet's activity around perihelion has shown similar behaviour during the last three orbital passages, it is fair to assume that the comet's behavior at large heliocentric distance has not changed from one orbital revolution to the other, leading us to expect that during its approach to 67P/CG, Rosetta will find the same conditions detected during our observations. A considerable difficulty in observing 67P/C-G during the past years has been its position against crowded fields towards the galactic centre for much of this time (Fig. 1 - top). The 2007/8 data presented here was particularly difficult, and the comet will once again be badly placed for Earth based observations in 2014/5. We made use of the technique of Difference Image Analysis (as implemented in the DanDIA software, [5]), which is commonly used in variable star and exoplanet research, to remove background sources and extract images of the comet (Fig. 1 - bottom). We determined that the comet became active during the period November 2007 - March 2008, at a distance of 4.1-3.4 AU from the Sun. The comet will reach this distance, and probably become active again, in April- September 2014. To investigate the longer period activity cycle of the comet we compiled the heliocentric light curve of the comet, making use of images of 67P/C-G taken during the last three apparitions taken from the ESO archive. A preliminary light curve is shown in 2. This information will be used for planning observing campaigns, both from the ground and using OSIRIS on board Rosetta.

Tubiana, C.; Snodgrass, C.; Bramich, D.; Boehnhardt, H.; Barrera, L.

2012-09-01

421

Effect of morning bright light treatment for rest-activity disruption in institutionalized patients with severe Alzheimer's disease  

Microsoft Academic Search

BACKGROUND: Disturbances in rest-activity rhythm are prominent and disabling symptoms in Alzheimer's disease (AD). Nighttime sleep is severely fragmented and daytime activity is disrupted by multiple napping episodes. In most institutional environments, light levels are very low and may not be sufficient to enable the circadian clock to entrain to the 24-hour day. The purpose of this randomized, placebo-controlled, clinical

Glenna A. Dowling; Erin M. Hubbard; Judy Mastick; Jay S. Luxenberg; Robert L. Burr; Someren van E. J. W

2005-01-01

422

Red-light- and gibberellic-acid-enhanced ?-galactosidase activity in germinating lettuce seeds, cv. Grand Rapids  

Microsoft Academic Search

Dry lettuce (Lactuca sativa L.) “seeds” (achenes) contain a-galactosidase (EC 3.2.122) at a level which is maintained in the imbibed dormant state in darkness. Both red light (R) and gibberellic acid promote an increase in enzyme activity several hours prior to the completion of germination. Germination and enzyme activity are not essentially linked, however, for the latter can increase while

David W. M. Leung; J. Derek Bewley

1981-01-01

423

Evidence for novel structures (primo vessels and primo nodes) floating in the venous sinuses of rat brains.  

PubMed

We for the first time report evidence for existence of novel structures, primo vessels (PVs) and primo nodes (PNs) floating inside the venous sinuses of rat brains. For this purpose, we applied a chromium-hematoxylin (Cr-Hx) solution to stain the PVs and the PNs floating inside the venous sinuses (superior sagittal sinus, strait sinus, and transverse sinus) of seven rats' brains preferentially compared to the blood clots that easily form during surgery. Cr-Hx-stained PVs and PNs were examined by light and transmission electron microscopies: (1) we were consistently able to visualize the PVs and the PNs in the venous sinuses of all seven rats' brains. (2) The PVs and PNs consisted of rod-shaped and some round-shaped cells, respectively, as demonstrated by using 4',6-diamidino-2-phenylindole (DAPI). (3) Cross sections of the PVs showed that the sinuses contained loose fibrous materials and clusters of nano-sized granules enveloped by the cortex. The above data imply that thrombus of the venous sinuses may be related with these novel floating structures. However, the functions of the PVs and PNs floating in the venous sinuses remain to be investigated in terms of normal or thrombus-provoked diseases. PMID:22728058

Lee, Ho-Sung; Park, Won-Hee; Je, A-Reum; Kweon, Hee-Seok; Lee, Byung-Cheon

2012-08-01

424

Differential Activation of Escherichia coli Chemoreceptors by Blue-Light Stimuli  

PubMed Central

Enteric bacteria tumble, swim slowly, and are then paralyzed upon exposure to 390- to 530-nm light. Here, we analyze this complex response in Escherichia coli using standard fluorescence microscope optics for excitation at 440 ± 5 nm. The slow swimming and paralysis occurred only in dye-containing growth media or buffers. Excitation elicited complete paralysis within a second in 1 ?M proflavine dye, implying specific motor damage, but prolonged tumbling in buffer alone. The tumbling half-response times were subsecond for onset but more than a minute for recovery. The response required the chemotaxis signal protein CheY and receptor-dependent activation of its kinase CheA. The study of deletion mutants revealed a specific requirement for either the aerotaxis receptor Aer or the chemoreceptor Tar but not the Tar homolog Tsr. The action spectrum of the wild-type response was consistent with a flavin, but the chromophores remain to be identified. The motile response processed via Aer was sustained, with recovery to either step-up or -down taking more than a minute. The response processed via Tar was transient, recovering on second time scales comparable to chemotactic responses. The response duration and amplitude were dependent on relative expression of Aer, Tar, and Tsr. The main response features were reproduced when each receptor was expressed singly from a plasmid in a receptorless host strain. However, time-resolved motion analysis revealed subtle kinetic differences that reflect the role of receptor cluster interactions in kinase activation-deactivation dynamics. PMID:16707688

Wright, Stuart; Walia, Bharat; Parkinson, John S.; Khan, Shahid

2006-01-01

425

BIO ARGO floats: tools for operational monitoring of the Black Sea  

NASA Astrophysics Data System (ADS)

The assessment of ecological status in the context of the Water Framework Directive (WFD) and Marine Strategy Framework Directive (MSFD) requires comprehensive knowledge and understanding of the physical and biogeochemical processes that determine the functioning of marine ecosystems. One of the main challenges however is the need of data with frequency relevant to the spatial and temporal scales of the ecological processes. The majority of in situ observations that are commonly used for ecological monitoring of the Black Sea are generally based on near-shore monitoring programs or irregular oceanographic cruises that provide either non-synoptic, coarse resolution realizations of large scale processes or detailed, but time and site specific snapshots of local features. These gaps can be filled by two independent sources: satellite observation and profiling floats. In fact satellite ocean color sensors allows for determination at synoptic scale of water quality parameters through its absorption properties. However the satellite ocean color methods have a number of limitations such as: measurements can only be made during daylight hours; require cloud-free conditions and are sensitive to atmospheric aerosols; provide information only for the upper layer of the ocean (approximately the depth of 10% incident light); algorithms developed for global applications are a source of large uncertainties in the marginal seas and costal areas. These constrains of the optical remote sensing observations can be avoided by using miniature biogeochemical sensors and autonomous platforms that offer remarkable perspectives for observing the "biological" ocean, notably at critical spatiotemporal scales which have been out of reach until recently (Claustre et al., 2010). In the frame of "E-AIMS: Euro-Argo Improvements for the GMES marine Service" 7 EC FP project two Bio Argo floats were deployed in the Black Sea. Beside the traditionally CTD the floats were equipped with biogeochemical sensors (oxygen, irradiance, chl-a and backscattering). The selection of the deployment locations was limited only to the Bulgarian Black Sea waters, so that the optimal deployment strategy that has been chosen was the floats to be deployed in the maximum distant positions from each other along the Black Sea geostrophic current at depth ~ 1800 m. Coincident biogeochemical and in-water radiometric measurements were collected at the time of each float deployment to ensure intercalibration of the instruments mounted on the floats and as well as to find empirical relationship between optical data and biogeochemical variables. The data obtained form Bio floats will be used to: investigate the seasonal evolution of oxygen in the upper layers, including the subsurface oxygen maximum; study the seasonal and inter annual dynamics of phytoplankton blooms in the deeper Black Sea; cross validation of satellite derived Chl-a and backscattering. References: Claustre et al. (2010). Bio-optical profiling floats as new observational tools for biogeochemical and ecosystem studies: potential synergies with ocean color remote sensing. Proceedings of the "OceanObs'09: Sustained Ocean Observations and Information for Society" Conference, Venice/Italy.

Palazov, Atanas; Slabakova, Violeta; Peneva, Elisaveta; Stanev, Emil

2014-05-01

426

Light activity following a meal and postprandial cardiometabolic risk in adolescents.  

PubMed

The purpose of this study was to determine if light physical activity (LPA) minimizes the impairment of cardiometabolic risk factors following a typical meal in adolescents. Eighteen adolescents (50% male, 14.8 ± 2.3 yrs) consumed a meal (32% fat, 14% protein, 53% carbohydrate), then completed a walking (1.5 mph for 45 min of each hour) or sitting treatment for 3 hr in randomized order on separate days. Following the meal, HDL cholesterol declined 4.8% but remained higher during walking at 3 hr (42.1 mg/dl ± 9.3) than sitting (8.4% decline; 40.5 mg/dL ± 9.9; treatment x time interaction, p < .03). The 3-hr insulin was lower after walking (24.8 ?IU/ml ± 33.4) than sitting (37.8 ?IU/ml ± 34.7; treatment x time interaction, p < .0001). Triglycerides increased by ~40% above baseline at 1 and 2 hr, with higher values for walking (treatment x time interaction, p < .02). However by 3 hr, triglycerides were not different from baseline. Area under the curve (AUC) analyses were not significantly different between treatments for any outcomes. Although minor, LPA appears to mitigate the undesirable postprandial changes in HDL cholesterol and insulin but not triglycerides, following a typical meal in adolescents. PMID:23501926

Sisson, Susan B; Anderson, Ashley E; Short, Kevin R; Gardner, Andrew W; Whited, Teresa; Robledo, Candace; Thompson, David M

2013-08-01

427

Optimal parameters for arterial repair using light-activated surgical adhesives.  

PubMed

The clinical acceptance of laser-tissue repair techniques is dependent on the reproducibility of viable repairs. Reproducibility is dependent on two factors: (i) the choice of materials to be used as the adhesive; and (ii) obtaining temperatures high enough to cause protein denaturation at the vital tissue interface without causing excessive thermal damage to the surrounding tissue. The use of a polymer scaffold as a carrier for the protein solder provides for uniform application of the solder to the tissue, thus allowing for pre-selection of optimal laser parameters. The scaffold also facilitates precise tissue alignment and ease of clinical application. In addition, the scaffold can be doped with various pharmaceuticals such as hemostatic and thrombogenic agents to aid wound healing. An ex vivo study was performed to correlate solder and tissue temperature with the tensile strength of arterial repairs formed using scaffold-enhanced light-activated surgical adhesives. Previous studies by our group using solid protein solder without the scaffold indicate that a solder/tissue, interface temperature of 65 degrees C is optimal. Using this parameter as a benchmark, laser irradiance was varied and temperatures were recorded at the surface and at the tissue interface of scaffold-enhanced protein solder using an infrared temperature monitoring system, designed by the researchers, and a type-K thermocouple, respectively. PMID:12724862

Soller, Eric C; Hoffman, Grant T; McNally-Heintzelman, Karen M

2003-01-01

428

Transparent thin films of Cu-TiO2 with visible light photocatalytic activity.  

PubMed

Thin films of Cu-TiO2 with a high level of transparency were prepared by a dip-coating procedure on the glass surface. CuCl2 was used as a copper precursor added during sol-gel synthesis of TiO2. The extension of optical absorption into the visible region of as-prepared thin films was indicated by UV/Vis spectroscopy. Only the anatase phase was detected by X-ray diffraction analysis (XRD). The presence of copper in the structure of thin films was confirmed by energy dispersive X-ray spectrometry (EDS). The significant rate of phenol and 4-chlorophenol mineralization was observed during visible light irradiation. The photocatalytic activity of the prepared thin films is correlated with the optimum copper content in the structure. Copper in metallic form and cupric oxides were not detected by XRD and scanning electron microscopy analysis. It is suggested that copper may exist as dispersed ions in the TiO2 lattice. PMID:25388411

Janczarek, Marcin; Zieli?ska-Jurek, Anna; Markowska, Irmina; Hupka, Jan

2014-11-12

429

NF-kB activation as a biomarker of light injury using a transgenic mouse model  

NASA Astrophysics Data System (ADS)

The spatial and temporal activation of NF-kB (p65) was monitored in the retina of a transgenic mouse model (cis-NFkB-EGFP) in vivo after receiving varying grades of laser induced thermal injury in one eye. Baseline images of the retinas from 26 mice were collected prior to injury and up to five months post-exposure using a Heidelberg Spectralis HRA confocal scanning laser ophthalmoscope (cSLO) with a spectral domain optical coherence tomographer (SDOCT). Injured and control eyes were enucleated at discrete time points following laser exposure for cryosectioning to determine localization of NF-kB dependent enhanced green fluorescent protein (EGFP) reporter gene expression within the retina using fluorescence microscopy. In addition, EGFP basal expression in brain and retinal tissue from the cis-NFkB-EGFP was characterized using two-photon imaging. Regions of the retina exposed to threshold and supra-threshold laser damage evaluated using fluorescence cSLO showed increased EGFP fluorescence localized to the exposed region for a duration that was dependent upon the degree of injury. Fluorescence microscopy of threshold damage revealed EGFP localized to the outer nuclear region and retinal pigment epithelial layer. Basal expression of EGFP imaged using two-photon microscopy was heterogeneously distributed throughout brain tissue and confined to the inner retina. Results show cis-NF-kB-EGFP reporter mouse can be used for in vivo studies of light induced injury to the retina and possibly brain injury.

Pocock, Ginger M.; Boretsky, Adam; Wang, Heuy-Ching; Golden, Dallas; Gupta, Praveena; Vargas, Gracie; Oliver, Jeffrey W.; Motamedi, Massoud

2012-03-01

430

Bismuth titanate pyrochlore microspheres: Directed synthesis and their visible light photocatalytic activity  

NASA Astrophysics Data System (ADS)

Bismuth titanates, Bi 2Ti 2O 7 (BIT), with well-defined spherical structures were synthesized by a facile hydrothermal process without the use of any surfactant or template. XRD and SEM studies have shown that spheres could be fabricated in high yields by simply manipulating the concentrations of hydroxide ions. In this case, hydroxide ions seem to play a pivotal role in controlling the formation of seeds and growth rates of the BIT particles. On the basis of structural analysis of samples obtained at different concentrations of OH -, we also proposed a plausible mechanism to account for the formation of these distinctive morphologies under different conditions. The as-prepared BIT microspheres with good stability exhibited higher photocatalytic activities in the degradation of Rhodamine B (RhB) under visible light irradiation than that in commercial P25 TiO 2. Furthermore, the enhanced photocatalytic performance for RhB degradation was also investigated with assistance of a small amount of H 2O 2.

Hou, Jungang; Jiao, Shuqiang; Zhu, Hongmin; Kumar, R. V.

2011-01-01

431

Efficient blue organic light-emitting diodes employing thermally activated delayed fluorescence  

NASA Astrophysics Data System (ADS)

Organic light-emitting diodes (OLEDs) employing thermally activated delayed fluorescence (TADF) have emerged as cheaper alternatives to high-performance phosphorescent OLEDs with noble-metal-based dopants. However, the efficiencies of blue TADF OLEDs are still low at high luminance, limiting full-colour display. Here, we report a blue OLED containing a 9,10-dihydroacridine/diphenylsulphone derivative that has a comparable performance to today's best phosphorescent OLEDs. The device offers an external quantum efficiency of 19.5% and reduced efficiency roll-off characteristics at high luminance. Through computational simulation, we identified six pretwisted intramolecular charge-transfer (CT) molecules with small singlet-triplet CT state splitting but different energy relationships between 3CT and locally excited triplet (3LE) states. Systematic comparison of their excited-state dynamics revealed that CT molecules with a large twist angle can emit efficient and short-lifetime (a few microseconds) TADF when the emission peak energy is high enough and the 3LE state is higher than the 3CT state.

Zhang, Qisheng; Li, Bo; Huang, Shuping; Nomura, Hiroko; Tanaka, Hiroyuki; Adachi, Chihaya

2014-04-01

432

Active matrix organic light emitting diode (OLED)-XL life test results  

NASA Astrophysics Data System (ADS)

OLED displays have been known to exhibit high levels of performance with regards to contrast, response time, uniformity, and viewing angle, but a lifetime improvement has been perceived to be essential for broadening the applications of OLED's in the military and in the commercial market. As a result of this need, the US Army and eMagin Corporation established a Cooperative Research and Development Agreement (CRADA) to improve the lifetime of OLED displays. In 2006, eMagin Corporation developed long-life OLED-XL devices for use in their AMOLED microdisplays for head-worn applications, and RDECOM CERDEC NVESD ran life tests on these displays, finding over 200% lifetime improvement for the XL devices over the standard displays. Early results were published at the 2007 SPIE Defense and Security Symposium. Further life testing of XL and standard devices at ambient conditions and at high temperatures will be presented this year along with a recap of previous data. This should result in a better understanding of the applicability of AMOLEDs in military and commercial head mounted systems: where good fits are made, and where further development might be needed. This is a continuation of the paper "Life test results of OLED-XL long-life devices for use in active matrix organic light emitting diode (AMOLED) displays for head mounted applications" presented at SPIE DSS in 2007.

Fellowes, David A.; Wood, Michael V.; Hastings, Arthur R., Jr.; Ghosh, Amalkumar P.; Prache, Olivier

2008-04-01

433

Fabrication and visible-light photocatalytic activity of novel Ag/TiO2-xNx nanocatalyst  

EPA Science Inventory

The efforts of the scientific community are directed towards the preparation of photocatalysts that are active under solar or artificial visible light irradiation. TiO2 is one of the most 15 widely used photocatalyst that is employed in self-cleaning coatings, photocatalytic proc...

434

Induction of Ig Light Chain Gene Rearrangement in Heavy Chain-Deficient B Cells by Activated Ras  

Microsoft Academic Search

During B cell development, rearrangement and expression of Ig heavy chain (HC) genes promote development and expansion of pre-B cells accompanied by the onset of Ig light chain (LC) variable region gene assembly. To elucidate the signaling pathways that control these events, we have tested the ability of activated Ras expression to promote B cell differentiation to the stage of

Albert C. Shaw; Wojciech Swat; Laurie Davidson; Frederick W. Alt

1999-01-01

435

UV-vis light activated Ag decorated monodisperse TiO2 for treatment of pharmaceuticals in water  

EPA Science Inventory

Recently, many researchers have made a lot of effort to utilize the visible light portion of the solar spectrum to activate TiO2 photocatalyst for environmental applications, such as water, air, and soil remediation. The deposition of noble metals on photocatalysts is of great in...

436

Structure of a light-activated LOV protein dimer that regulates transcription in Neurospora crassa  

PubMed Central

Light oxygen or voltage (LOV) domains are widely represented signaling modules in bacteria, archea, protists, plants and fungi. The Neurospora crassa LOV protein VIVID (VVD) allows adaptation to constant or increasing light levels and proper entrainment of circadian rhythms. The crystal structure of the fully light-adapted VVD dimer reveals the mechanism by which light driven conformational change alters oligomeric state. Photo-induced formation of a cysteinyl-flavin adduct generates a new hydrogen bond network that releases the N-terminus from the protein core and restructures an acceptor pocket for its binding on the opposite subunit. Substitution of residues key to the monomer/dimer switch have profound effects on light adaptation in Neurospora. The VVD dimerization mechanism provides the molecular details for how a large family of photoreceptors converts light responses to alterations in protein interactions. PMID:21868352

Vaidya, Anand T.; Chen, Chen-Hui; Dunlap, Jay C.; Loros, Jennifer J.; Crane, Brian R.

2012-01-01