Wavelength-switchable passively mode-locked fiber laser with mechanically exfoliated molybdenum ditelluride on side-polished fiber

NASA Astrophysics Data System (ADS)

Wang, Guomei

2017-11-01

We experimentally investigated the nonlinear saturable absorption characteristics of molybdenum ditelluride (MoTe2) and demonstrated a wavelength-switchable mode-locked erbium-doped fiber laser (EDFL) by using MoTe2 thin film on side-polished fiber (SPF) as saturable absorber. Here, the MoTe2 thin film was efficiently fabricated via mechanical exfoliation method and transferred onto the SPF with the assistance of polydimethylsiloxane (PDMS). MoTe2-covered SPF (MSPF) exhibits the nonlinear saturable absorption for pulses with different polarization states. Optical solitons with spectral bandwidth of 1.06 (1.31) nm centered at ∼1559 (∼1528) nm and pulse duration of 2.46 (2.04) ps can be obtained from the EDFL by adjusting the polarization controller (PC) properly. The time-bandwidth product (TBP) of the pulses was calculated as 0.322 (0.344).

Passively mode-locked soliton femtosecond pulses employing graphene saturable absorber

NASA Astrophysics Data System (ADS)

Lau, K. Y.; Muhammad, F. D.; Latif, A. A.; Abu Bakar, M. H.; Yusoff, Z.; Mahdi, M. A.

2017-09-01

We demonstrate a passively mode-locked fiber laser incorporating graphene thin film (GTF) as saturable absorber (SA). The SA is fabricated by sandwiching the GTF between two single mode fiber ferrules through a fiber adaptor. The transmission loss at 1560 nm and non-linear saturation absorption modulation depth for GTF-SA are 0.8 dB and 2.90%, respectively. An erbium-doped fiber laser cavity is constructed to verify the functionality of GTF-SA and is designed to have net anomalous dispersion. It generates large spectral width of 4.99 nm with pulse repetition rate of 9.655 MHz and pulse width of 670 fs. Net anomalous dispersion and time bandwidth product higher than the sech2 transform-limited pulse validate the experimental result. In short, we demonstrate high performance GTF-SA that is able to generate ultrafast pulse duration in femtosecond range effortlessly with simple and green SA fabrication procedures.

Micro-poromechanics model of fluid-saturated chemically active fibrous media.

PubMed

Misra, Anil; Parthasarathy, Ranganathan; Singh, Viraj; Spencer, Paulette

2015-02-01

We have developed a micromechanics based model for chemically active saturated fibrous media that incorporates fiber network microstructure, chemical potential driven fluid flow, and micro-poromechanics. The stress-strain relationship of the dry fibrous media is first obtained by considering the fiber behavior. The constitutive relationships applicable to saturated media are then derived in the poromechanics framework using Hill's volume averaging. The advantage of this approach is that the resultant continuum model accounts for the discrete nature of the individual fibers while retaining a form suitable for porous materials. As a result, the model is able to predict the influence of micro-scale phenomena, such as the fiber pre-strain caused by osmotic effects and evolution of fiber network structure with loading, on the overall behavior and in particular, on the poromechanics parameters. Additionally, the model can describe fluid-flow related rate-dependent behavior under confined and unconfined conditions and varying chemical environments. The significance of the approach is demonstrated by simulating unconfined drained monotonic uniaxial compression under different surrounding fluid bath molarity, and fluid-flow related creep and relaxation at different loading-levels and different surrounding fluid bath molarity. The model predictions conform to the experimental observations for saturated soft fibrous materials. The method can potentially be extended to other porous materials such as bone, clays, foams and concrete.

Generation of an ultrafast femtosecond soliton fiber laser by carbon nanotube as saturable absorber

NASA Astrophysics Data System (ADS)

Salim, M. A. M.; Ahmad, H.; Harun, S. W.; Bidin, N.; Krishnan, G.

2018-05-01

This paper reports the demonstration of ultrafast fiber laser in a simple erbium-doped fiber (EDF) laser that employed a carbon nanotube (CNT) thin film saturable absorber (SA) to generate a stable soliton pulse. The repetition rate of 10.8 MHz pulse consistently achieved has narrowest pulse width of 640 fs and 1555.78 nm central wavelength for an hour operation in room temperature. This proposed setup has the capability for reliable and stable system features.

Dark soliton fiber lasers.

PubMed

Tang, Dingyuan; Guo, Jun; Song, Yufeng; Zhang, Han; Zhao, Luming; Shen, Deyuan

2014-08-11

Dark soliton formation and soliton dynamics in all-normal dispersion cavity fiber ring lasers without an anti-saturable absorber in cavity is studied both theoretically and numerically. It is shown that under suitable conditions the dark solitons formed could be described by the nonlinear Schrödinger equation. The dark soliton formation in an all-normal-dispersion cavity erbium-doped fiber ring laser without an anti-saturable absorber in cavity is first experimentally demonstrated. Individual dark solitons are experimentally identified. Excellent agreement between theory and experiment is observed.

Hybrid mode-locked fiber ring laser using graphene and charcoal nanoparticles as saturable absorbers

NASA Astrophysics Data System (ADS)

Hu, Hongyu; Zhang, Xiang; Li, Wenbo; Dutta, Niloy K.

2016-05-01

A fiber ring laser which implements hybrid mode locking technique has been proposed and experimentally demonstrated to generate pulse train at 20 GHz repetition rate with ultrashort pulse width. Graphene and charcoal nano-particles acting as passive mode lockers are inserted into a rational harmonic mode-locked fiber laser to improve the performance. With graphene saturable absorbers, the pulse duration is shortened from 5.3 ps to 2.8 ps, and with charcoal nano-particles, it is shortened to 3.2 ps. The RF spectra show that supermode noise can be removed in the presence of the saturable absorbers. Numerical simulation of the pulse transmission has also been carried out, which shows good agreement with the experimental results.

Widely-tunable, passively Q-switched erbium-doped fiber laser with few-layer MoS2 saturable absorber.

PubMed

Huang, Yizhong; Luo, Zhengqian; Li, Yingyue; Zhong, Min; Xu, Bin; Che, Kaijun; Xu, Huiying; Cai, Zhiping; Peng, Jian; Weng, Jian

2014-10-20

We propose and demonstrate a MoS2-based passively Q-switched Er-doped fiber laser with a wide tuning range of 1519.6-1567.7 nm. The few-layer MoS2 nano-platelets are prepared by the liquid-phase exfoliation method, and are then made into polymer-composite film to construct the fiber-compatible MoS2 saturable absorber (SA). It is measured at 1560 nm wavelength, that such MoS2 SA has the modulation depth of ∼ 2% and the saturable optical intensity of ∼ 10 MW/cm(2). By further inserting the filmy MoS2-SA into an Er-doped fiber laser, stable Q-switching operation with a 48.1 nm continuous tuning from S- to C-waveband is successfully achieved. The shortest pulse duration and the maximum pulse energy are 3.3 μs and 160 nJ, respectively. The repetition rate and the pulse duration under different operation conditions have been also characterized. To the best of our knowledge, it is the first demonstration of MoS2 Q-switched, widely-tunable fiber laser.

Single-wall carbon nanotubes and graphene oxide-based saturable absorbers for low phase noise mode-locked fiber lasers

PubMed Central

Li, Xiaohui; Wu, Kan; Sun, Zhipei; Meng, Bo; Wang, Yonggang; Wang, Yishan; Yu, Xuechao; Yu, Xia; Zhang, Ying; Shum, Perry Ping; Wang, Qi Jie

2016-01-01

Low phase noise mode-locked fiber laser finds important applications in telecommunication, ultrafast sciences, material science, and biology, etc. In this paper, two types of carbon nano-materials, i.e. single-wall carbon nanotube (SWNT) and graphene oxide (GO), are investigated as efficient saturable absorbers (SAs) to achieve low phase noise mode-locked fiber lasers. Various properties of these wall-paper SAs, such as saturable intensity, optical absorption and degree of purity, are found to be key factors determining the performance of the ultrafast pulses. Reduced-noise femtosecond fiber lasers based on such carbon-based SAs are experimentally demonstrated, for which the phase noise has been reduced by more than 10 dB for SWNT SAs and 8 dB for GO SAs at 10 kHz. To the best of our knowledge, this is the first investigation on the relationship between different carbon material based SAs and the phase noise of mode-locked lasers. This work paves the way to generate high-quality low phase noise ultrashort pulses in passively mode-locked fiber lasers. PMID:27126900

Construction and Passive Q-Switching of a Ring-Cavity Erbium-Doped Fiber Laser Using Carbon Nanotubes as a Saturable Absorber

NASA Astrophysics Data System (ADS)

Scott, Austin Murphy

The purpose of this thesis is to design, build, test, and achieve pulsed operation of a ring-cavity erbium-doped fiber laser using carbon nanotubes as a saturable absorber. The erbium-doped fiber is characterized first, cross-sections are calculated, and the gain value is determined. Subsequently, the ring cavity is constructed and the laser is operated in the continuous wave regime. Much time is then spent trying to characterize and utilize the carbon nanotubes successfully. Many dispersions are made using multiple solvents and dispersing media, various images are taken with both scanning electron and Raman microscopy, and attempts at purification are made. Saturable absorbers are then created both by coating the end facet of a fiber with a dispersion containing carbon nanotubes and by inserting a fabricated poly-methyl-methacrylate (PMMA) and single-walled carbon nanotube (SWCNT) polymer composite film between two fiber end facets. Once inserted into the cavity, the saturable absorbers passively Q-switch the laser in three distinct cases. A fiber end facet coating of SWCNTs dispersed into isopropanol produced pulses with duration of 17.45 +/- 0.11 micros and 2.74 +/- 0.14 micros, with repetition rates of 25.36 +/- 0.53 kHz and 37.77 +/- 0.33 kHz, respectively. A second fiber end facet coating of SWCNTs dispersed into dimethylformamide (DMF) produced pulses with duration of 12.28 +/- 1.08 micros and 3.58 +/- 0.12 micros, with repetition rates of 25.13 +/- 0.63 kHz and 26.46 +/- 0.13 kHz, respectively. The PMMA plus SWCNT polymer composite film produced pulses of 0.716 +/- 0.007 micros duration and 142.8 +/- 1 kHz repetition rate.

All-fiber thulium/holmium-doped mode-locked laser by tungsten disulfide saturable absorber

NASA Astrophysics Data System (ADS)

Yu, Hao; Zheng, Xin; Yin, Ke; Cheng, Xiang'ai; Jiang, Tian

2017-01-01

A passively mode-locked thulium/holmium-doped fiber laser (THDFL) based on tungsten disulfide (WS2) saturable absorber (SA) was demonstrated. The WS2 nanosheets were prepared by liquid phase exfoliation method and the SA was fabricated by depositing the few-layer WS2 nanosheets on the surface of a fiber taper. The modulation depth, saturable intensity, and non-saturable loss of this SA were measured to be 8.2%, 0.82 GW cm-2, and 29.4%, respectively. Based on this SA, a stable mode-locked laser operated at 1.91 µm was achieved with pulse duration of 825 fs and repetition rate of 15.49 MHz, and signal-to-noise ratio (SNR) of 67 dB. Meanwhile, by increasing the pump power and adjusting the position of polarization controller, harmonic mode-locking operations were obtained. These results showed that the WS2 nanosheet-based SA could be served as a desirable candidate for a short-pulse mode locker at 2 µm wavelength.

Passively Q-switched dual-wavelength thulium-doped fiber laser based on a multimode interference filter and a semiconductor saturable absorber

NASA Astrophysics Data System (ADS)

Wang, M.; Huang, Y. J.; Ruan, S. C.

2018-04-01

In this paper, we have demonstrated a theta cavity passively Q-switched dual-wavelength fiber laser based on a multimode interference filter and a semiconductor saturable absorber. Relying on the properties of the fiber theta cavity, the laser can operate unidirectionally without an optical isolator. A semiconductor saturable absorber played the role of passive Q-switch while a section of single-mode-multimode-single-mode fiber structure served as an multimode interference filter and was used for selecting the lasing wavelengths. By suitably manipulating the polarization controller, stable dual-wavelength Q-switched operation was obtained at ~1946.8 nm and ~1983.8 nm with maximum output power and minimum pulse duration of ~47 mW and ~762.5 ns, respectively. The pulse repetition rate can be tuned from ~20.2 kHz to ~79.7 kHz by increasing the pump power from ~2.12 W to ~5.4 W.

Poromechanics Parameters of Fluid-Saturated Chemically Active Fibrous Media Derived from a Micromechanical Approach.

PubMed

Misra, Anil; Parthasarathy, Ranganathan; Singh, Viraj; Spencer, Paulette

2013-01-01

The authors have derived macroscale poromechanics parameters for chemically active saturated fibrous media by combining microstructure-based homogenization with Hill's volume averaging. The stress-strain relationship of the dry fibrous media is first obtained by considering the fiber behavior. The constitutive relationships applicable to saturated media are then derived in the poromechanics framework using Hill's Lemmas. The advantage of this approach is that the resultant continuum model assumes a form suited to study porous materials, while retaining the effect of discrete fiber deformation. As a result, the model is able to predict the influence of microscale phenomena such as fiber buckling on the overall behavior, and in particular, on the poromechanics constants. The significance of the approach is demonstrated using the effect of drainage and fiber nonlinearity on monotonic compressive stress-strain behavior. The model predictions conform to the experimental observations for articular cartilage. The method can potentially be extended to other porous materials such as bone, clays, foams, and concrete.

Development and optimization of a miniaturized fiber-optic photoplethysmographic sensor

NASA Astrophysics Data System (ADS)

Morley, Aisha; Davenport, John J.; Hickey, Michelle; Phillips, Justin P.

2017-11-01

Photoplethysmography (PPG) is a widely used technique for measuring blood oxygen saturation, commonly using an external pulse oximeter applied to a finger, toe, or earlobe. Previous research has demonstrated the utility of direct monitoring of the oxygen saturation of internal organs, using optical fibers to transmit light between the photodiode/light emitting diode and internal site. However, little research into the optimization and standardization of such a probe has yet been carried out. This research establishes the relationship between fiber separation distance and PPG signal, and between fiber core width and PPG signal. An ideal setup is suggested: 1000-μm fibers at a separation distance of 3 to 3.5 mm, which was found to produce signals around 0.35 V in amplitude with a low variation coefficient.

Switchable single-longitudinal-mode dual-wavelength erbium-doped fiber ring laser based on one polarization-maintaining fiber Bragg grating incorporating saturable absorber and feedback fiber loop

NASA Astrophysics Data System (ADS)

Feng, Suchun; Xu, Ou; Lu, Shaohua; Ning, Tigang; Jian, Shuisheng

2009-06-01

Switchable single-longitudinal-mode (SLM) dual-wavelength erbium-doped fiber ring laser based on one polarization-maintaining fiber Bragg grating (PMFBG) is demonstrated. Due to the enhancement of the polarization hole burning (PHB) by the PMFBG, the laser can be designed to operate in stable dual-wavelength or wavelength-switching modes with a wavelength spacing of 0.336 nm at room temperature by adjusting a polarization controller (PC). The stable SLM operation is guaranteed by a compound-ring cavity and a saturable absorber (SA). The optical signal-to-noise ratio (OSNR) is over 45 dB. The amplitude variation in nearly one and half an hour is less than 0.2 dB.

Tungsten disulphide based all fiber Q-switching cylindrical-vector beam generation

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

Lin, J.; Yan, K.; Zhou, Y.

2015-11-09

We proposed and demonstrated an all fiber passively Q-switching laser to generate cylindrical-vector beam, a two dimensional material, tungsten disulphide (WS{sub 2}), was adopted as a saturable absorber inside the laser cavity, while a few-mode fiber Bragg grating was used as a transverse mode-selective output coupler. The repetition rate of the Q-switching output pulses can be varied from 80 kHz to 120 kHz with a shortest duration of 958 ns. Attributed to the high damage threshold and polarization insensitivity of the WS{sub 2} based saturable absorber, the radially polarized beam and azimuthally polarized beam can be easily generated in the Q-switching fiber laser.

Moisture in untreated, acetylated, and furfurylated Norway Spruce monitored during drying below fiber saturation using time domain NMR

Treesearch

Lisbeth G. Thygesen; Thomas Elder

2009-01-01

Using time domain–nuclear magnetic resonance spectroscopy, the moisture content (MC) in Norway spruce [Picea abies (L.) Karst.] sapwood, subjected to three different treatments (untreated, acetylated, and furfurylated), was studied during drying at 40oC at MCs below fiber saturation. Spin–spin relaxation time distributions were derived from Carr-Purcell-...

Insights from in-situ X-ray computed tomography during axial impregnation of unidirectional fiber beds

DOE PAGES

Larson, Natalie M.; Zok, Frank W.

2017-12-27

In-situ X-ray computed tomography during axial impregnation of unidirectional fiber beds is used to study coupled effects of fluid velocity, fiber movement and preferred flow channeling on permeability. Here, in order to interpret the experimental measurements, a new computational tool for predicting axial permeability of very large 2D arrays of non-uniformly packed fibers is developed. The results show that, when the impregnation velocity is high, full saturation is attained behind the flow front and the fibers rearrange into a less uniform configuration with higher permeability. In contrast, when the velocity is low, fluid flows preferentially in the narrowest channels betweenmore » fibers, yielding unsaturated permeabilities that are lower than those in the saturated state. Lastly, these insights combined with a new computational tool will enable improved prediction of permeability, ultimately for use in optimization of composite manufacturing via liquid impregnation.« less

Switchable single-longitudinal-mode dual-wavelength erbium-doped fiber laser based on one polarization-maintaining fiber Bragg grating incorporating saturable absorber

NASA Astrophysics Data System (ADS)

Feng, Suchun; Xu, Ou; Lu, Shaohua; Chen, Ming; Jian, Shuisheng

2009-08-01

Switchable single-longitudinal-mode (SLM) dual-wavelength erbium-doped fiber laser at room temperature is demonstrated. One fiber Bragg grating (FBG) directly written in a polarization-maintaining and photosensitive erbiumdoped fiber (PMPEDF) as the wavelength-selective component is used in a linear laser cavity. Due to the polarization hole burning (PHB) enhanced by the polarization-maintaining fiber Bragg grating (PMFBG), the laser can be designed to operate in stable dual-wavelength or wavelength-switching modes with a wavelength spacing of 0.202 nm by adjusting a polarization controller (PC). The stable SLM operation is guaranteed by a saturable absorber (SA). The optical signal-tonoise ratio (OSNR) of the laser is over 40 dB. The amplitude variation in nearly one and half an hour is less than 0.5 dB for both wavelengths.

Insights from in-situ X-ray computed tomography during axial impregnation of unidirectional fiber beds

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

Larson, Natalie M.; Zok, Frank W.

In-situ X-ray computed tomography during axial impregnation of unidirectional fiber beds is used to study coupled effects of fluid velocity, fiber movement and preferred flow channeling on permeability. Here, in order to interpret the experimental measurements, a new computational tool for predicting axial permeability of very large 2D arrays of non-uniformly packed fibers is developed. The results show that, when the impregnation velocity is high, full saturation is attained behind the flow front and the fibers rearrange into a less uniform configuration with higher permeability. In contrast, when the velocity is low, fluid flows preferentially in the narrowest channels betweenmore » fibers, yielding unsaturated permeabilities that are lower than those in the saturated state. Lastly, these insights combined with a new computational tool will enable improved prediction of permeability, ultimately for use in optimization of composite manufacturing via liquid impregnation.« less

Thermal Stress-Induced Depolarization Loss in Conventional and Panda-Shaped Photonic Crystal Fiber Lasers

NASA Astrophysics Data System (ADS)

Mousavi, Seyedeh Laleh; Sabaeian, Mohammad

2016-10-01

We report on the modeling of the depolarization loss in the conventional and panda-shaped photonic crystal fiber lasers (PCFLs) due to the self-heating of the fiber, which we call it thermal stress-induced depolarization loss (TSIDL). We first calculated the temperature distribution over the fiber cross sections and then calculated the thermal stresses/strains as a function of heat load per meter. Thermal stress-induced birefringence (TSIB), which is defined as | n x - n y |, in the core and cladding regions was calculated. Finally, TSIDL was calculated for the conventional and panda-shaped PCFLs as a function of fiber length and, respectively, saturated values of 22 and 25 % were obtained which were independent of heat load per meter. For panda-shaped PCFLs, prior to being saturated, an oscillating and damping behavior against the fiber length was seen where in some lengths reached 35 %. The results are close to an experimental value of 30 % reported for a pulsed PCFL (Limpert et al., Opt Express 12:1313-1319, 2004) where the authors reported a degree of polarization of 70 % (i.e., a depolarization of 30 %). The most important result of this work is a saturation behavior of TSIDL at long-enough lengths of the fiber laser which is independent of heat load per meter. To our knowledge, this the first report of TSIBL for PCFLs.

Effect of absorption recovery in bismuth-doped silica glass at 1450 nm on soliton grouping in fiber laser

PubMed Central

Gumenyuk, R.; Melkumov, M. A.; Khopin, V. F.; Dianov, E. M.; Okhotnikov, O. G.

2014-01-01

Saturable absorption in bismuth-doped glasses was found to have a noticeable influence on soliton interaction and group formation. This phenomenon, observed in 1450 nm mode-locked bismuth-doped fiber laser, shows the distinct feature of the multiple pulse regime, which appears as a stationary pulse group whose length can be spread over the whole cavity length by variation of the pump power and polarization. Pulse positioning within the ensemble depends on the saturation fluence and the relatively fast recovery dynamics of bismuth fiber. PMID:25391808

Graphene Oxide saturable absorber for generating eye-safe Q-switched fiber laser

NASA Astrophysics Data System (ADS)

Rosol, A. H. A.; Jusoh, Z.; Rahman, H. A.; Rusdi, M. F. M.; Harun, S. W.; Latiff, A. A.

2017-06-01

This paper reports the generation of Q-switched fiber laser using thulium doped fiber (TDF) as a gain medium and graphene oxide (GO) as a saturable absorber (SA). The GO powder is embedded into polyvinyl alcohol (PVA) to form an SA film based on a drop-casting technique. GO-SA film is sandwiched between two fiber connectors and tighten by FC adapter before it is incorporated into an TDF laser cavity for Q-switching pulse generation. At 344 mW pump level, a stable Q-switching regime presence at 1943 nm with a 3-dB spectral bandwidth of 9 nm. The maximum repetition rate, pulse width, and pulse energy are at 25 kHz, 4.2 µs, and 0.68 µJ, respectively. All finding results are comparable with other reported pulse fiber lasers.

Properties of a vector soliton laser passively mode-locked by a fiber-based semiconductor saturable absorber operating in transmission

NASA Astrophysics Data System (ADS)

Ouyang, Chunmei; Wang, Honghai; Shum, Ping; Fu, Songnian; Wong, Jia Haur; Wu, Kan; Lim, Desmond Rodney Chin Siong; Wong, Vincent Kwok Huei; Lee, Kenneth Eng Kian

2011-01-01

We experimentally demonstrate a passively mode-locked fiber laser employing a fiber-based semiconductor saturable absorber (SSA) operating in transmission. Polarization rotation locked vector solitons are observed in the laser. Due to the intrinsic dynamic feature of the laser, period-doubling of these vector solitons has also been observed. Furthermore, extra spectral sidebands are formed on the optical spectrum, caused by the energy exchange between the two orthogonal polarization components of the vector solitons. By careful reduction of the pump power together with fine adjustment to the cavity birefringence, period-one state can further be obtained. Additionally, the phase noise properties of the vector soliton fiber laser have also been characterized experimentally and analytically.

WS2 mode-locked ultrafast fiber laser

PubMed Central

Mao, Dong; Wang, Yadong; Ma, Chaojie; Han, Lei; Jiang, Biqiang; Gan, Xuetao; Hua, Shijia; Zhang, Wending; Mei, Ting; Zhao, Jianlin

2015-01-01

Graphene-like two dimensional materials, such as WS2 and MoS2, are highly anisotropic layered compounds that have attracted growing interest from basic research to practical applications. Similar with MoS2, few-layer WS2 has remarkable physical properties. Here, we demonstrate for the first time that WS2 nanosheets exhibit ultrafast nonlinear saturable absorption property and high optical damage threshold. Soliton mode-locking operations are achieved separately in an erbium-doped fiber laser using two types of WS2-based saturable absorbers, one of which is fabricated by depositing WS2 nanosheets on a D-shaped fiber, while the other is synthesized by mixing WS2 solution with polyvinyl alcohol, and then evaporating them on a substrate. At the maximum pump power of 600 mW, two saturable absorbers can work stably at mode-locking state without damage, indicating that few-layer WS2 is a promising high-power flexible saturable absorber for ultrafast optics. Numerous applications may benefit from the ultrafast nonlinear features of WS2 nanosheets, such as high-power pulsed laser, materials processing, and frequency comb spectroscopy. PMID:25608729

A solution thermodynamics definition of the fiber saturation point and the derivation of a wood-water phase (state) diagram

Treesearch

Samuel L. Zelinka; Samuel V. Glass; Joseph E. Jakes; Donald S. Stone

2016-01-01

The fiber saturation point (FSP) is an important concept in wood– moisture relations that differentiates between the states of water in wood and has been discussed in the literature for over 100 years. Despite its importance and extensive study, the exact theoretical definition of the FSP and the operational definition (the correct way to measure the FSP) are still...

Passively Q-switched Tm-doped fiber laser based on concave gold bipyramids assembled quasi-2D saturable absorber

NASA Astrophysics Data System (ADS)

Song, Jiaxin; Wu, Hanshuo; Wu, Jian; Xu, Jiangming; Xiao, Hu; Leng, Jinyong; Zhou, Pu; Liu, Zejin

2018-07-01

We demonstrated a concave gold bipyramids (CAuBPs) quasi-2D saturable absorbers (SAs) based ~2 μm band fiber laser for the first time. CAuBPs were synthesized by using modified aqueous wet-chemical synthesis method. Through controlling the size and morphology of CAuBPs, the longitudinal surface plasmon resonance peak of CAuBPs based quasi-2D SA is tuned to be ~2 μm. Passively Q-switched lasing of thulium-doped fiber laser is achieved successfully with a maximum average output power of 9.72 mW and ~9% slope efficiency. The minimum pulse width is 4.56 µs at the repetition rate of 20 kHz. Experimental results reveals that CAuBPs could be used as SAs in the 2 µm region, which verifies the saturable absorption properties of CAuBPs.

All-fiber mode-locked laser oscillator with pulse energy of 34 nJ using a single-walled carbon nanotube saturable absorber.

PubMed

Jeong, Hwanseong; Choi, Sun Young; Rotermund, Fabian; Cha, Yong-Ho; Jeong, Do-Young; Yeom, Dong-Il

2014-09-22

We demonstrate a dissipative soliton fiber laser with high pulse energy (>30 nJ) based on a single-walled carbon nanotube saturable absorber (SWCNT-SA). In-line SA that evanescently interacts with the high quality SWCNT/polymer composite film was fabricated under optimized conditions, increasing the damage threshold of the saturation fluence of the SA to 97 mJ/cm(2). An Er-doped mode-locked all-fiber laser operating at net normal intra-cavity dispersion was built including the fabricated in-line SA. The laser stably delivers linearly chirped pulses with a pulse duration of 12.7 ps, and exhibits a spectral bandwidth of 12.1 nm at the central wavelength of 1563 nm. Average power of the laser output is measured as 335 mW at an applied pump power of 1.27 W. The corresponding pulse energy is estimated to be 34 nJ at the fundamental repetition rate of 9.80 MHz; this is the highest value, to our knowledge, reported in all-fiber Er-doped mode-locked laser using an SWCNT-SA.

Optical fiber-mediated photosynthesis for enhanced subsurface oxygen delivery.

PubMed

Lanzarini-Lopes, Mariana; Delgado, Anca G; Guo, Yuanming; Dahlen, Paul; Westerhoff, Paul

2018-03-01

Remediation of polluted groundwater often requires oxygen delivery into subsurface to sustain aerobic bacteria. Air sparging or injection of oxygen containing solutions (e.g., hydrogen peroxide) into the subsurface are common. In this study visible light was delivered into the subsurface using radially emitting optical fibers. Phototrophic organisms grew near the optical fiber in a saturated sand column. When applying light in on-off cycles, dissolved oxygen (DO) varied from super saturation levels of >15 mg DO/L in presence of light to under-saturation (<5 mg DO/L) in absence of light. Non-photosynthetic bacteria dominated at longer radial distances from the fiber, presumably supported by soluble microbial products produced by the photosynthetic microorganisms. The dissolved oxygen variations alter redox condition changes in response to light demonstrate the potential to biologically deliver oxygen into the subsurface and support a diverse microbial community. The ability to deliver oxygen and modulate redox conditions on diurnal cycles using solar light may provide a sustainable, long term strategy for increasing dissolved oxygen levels in subsurface environments and maintaining diverse biological communities. Copyright © 2017 Elsevier Ltd. All rights reserved.

Tm-doped fiber laser mode-locking with MoS2-polyvinyl alcohol saturable absorber

NASA Astrophysics Data System (ADS)

Cao, Liming; Li, Xing; Zhang, Rui; Wu, Duanduan; Dai, Shixun; Peng, Jian; Weng, Jian; Nie, Qiuhua

2018-03-01

We have designed an all-fiber passive mode-locking thulium-doped fiber laser that uses molybdenum disulfide (MoS2) as a saturable absorber (SA) material. A free-standing few-layer MoS2-polyvinyl alcohol (PVA) film is fabricated by liquid phase exfoliation (LPE) and is then transferred onto the end face of a fiber connector. The excellent saturable absorption of the fabricated MoS2-based SA allows the laser to output soliton pulses at a pump power of 500 mW. Fundamental frequency mode-locking is realized at a repetition frequency of 13.9 MHz. The central wavelength is 1926 nm, the 3 dB spectral bandwidth is 2.86 nm and the pulse duration is 1.51 ps. Additionally, third-order harmonic mode-locking of the laser is also achieved. The pulse duration is 1.33 ps, which is slightly narrower than the fundamental frequency mode-locking bandwidth. The experimental results demonstrate that the few-layer MoS2-PVA SA is promising for use in 2 μm laser systems.

Watt-level passively Q-switched heavily Er3+-doped ZBLAN fiber laser with a semiconductor saturable absorber mirror

PubMed Central

Shen, Yanlong; Wang, Yishan; Luan, Kunpeng; Huang, Ke; Tao, Mengmeng; Chen, Hongwei; Yi, Aiping; Feng, Guobin; Si, Jinhai

2016-01-01

A diode-cladding pumped mid-infrared passively Q-switched Er3+-doped ZBLAN fiber laser with an average output power of watt-level based on a semiconductor saturable absorber mirror (SESAM) is demonstrated. Stable pulse train was produced at a slope efficiency of 17.8% with respect to launched pump power. The maximum average power of 1.01 W at a repetition rate of 146.3 kHz was achieved with a corresponding pulse energy of 6.9 μJ, from which the maximum peak power was calculated to be 21.9 W. To the best of our knowledge, the average power and the peak power are the highest in 3 μm region passively Q-switched fiber lasers. The influence of gain fiber length on the operation regime of the fiber laser has been investigated in detail. PMID:27225029

Oats

MedlinePlus

... saturated fat. For each gram of soluble fiber (beta-glucan) consumed, total cholesterol decreases by about 1.42 ... total cholesterol than foods containing oat bran plus beta-glucan soluble fiber. The FDA recommends that approximately 3 ...

Investigation of the laser pumping power impact on the operating regimes of a laser passively Q-switched by a saturated absorber

NASA Astrophysics Data System (ADS)

Benarab, Mustapha; Mokdad, Rabah; Djellout, Hocine; Benfdila, Arezki; Lamrous, Omar; Meyrueis, Patrick

2011-09-01

We have adapted the point model for the study of an all-fiber laser doped with Nd3+ and Q-switched by a saturable fiber absorber doped with Cr4+. Calculations of the output power of the 1084 nm laser are considered as a function of the pump power supplied by a 790 nm laser diode. The analysis of the simulation results reveals the existence of pulsed, sinusoidal, and dc operating regimes.

The simultaneous generation of soliton bunches and Q-switched-like pulses in a partially mode-locked fiber laser with a graphene saturable absorber

NASA Astrophysics Data System (ADS)

Wang, Zhenhong; Wang, Zhi; Liu, Yan-ge; He, Ruijing; Wang, Guangdou; Yang, Guang; Han, Simeng

2018-05-01

We experimentally report the coexistence of soliton bunches and Q-switched-like pulses in a partially mode-locked fiber laser with a microfiber-based graphene saturable absorber. The soliton bunches, like isolated spikes with extreme amplitude and ultrashort duration, randomly generate in the background of the Q-switched-like pulses. The soliton bunches have some pulse envelopes in which pulses operate at a fundamental repetition rate in the temporal domain. Further investigation shows that the composite pulses are highly correlated with the noise-like pulses. Our work can make a further contribution to enrich the understanding of the nonlinear dynamics in fiber lasers.

Carbon Nanotube Mode-Locked Thulium Fiber Laser With 200 nm Tuning Range

PubMed Central

Meng, Yafei; Li, Yao; Xu, Yongbing; Wang, Fengqiu

2017-01-01

We demonstrated a mode-locked thulium/holmium (Tm/Ho) fiber laser continuously tunable across 200 nm (from 1860 nm to 2060 nm), which to the best of our knowledge represents the widest tuning range ever achieved for a passively mode-locked fiber laser oscillator. The combined use of a broadband carbon nanotube (CNT) saturable absorber and a diffraction grating mirror ensures ultra-broad tuning range, superb stability and repeatability, and makes the demonstrated laser a highly practical source for spectroscopy, imaging and optical communications. The laser emits <5 ps pulses with an optical spectral bandwidth of ∼3 nm across the full tuning range. Our results indicate that carbon nanotubes can be an excellent saturable absorber for achieving gain-bandwidth-limited tunable operation for 2 μm thulium fiber lasers. PMID:28322327

Mo0.5W0.5S2 for Q-switched pulse generation in ytterbium-doped fiber laser.

PubMed

Wang, Junli; Chen, Lei; Dou, Chenxi; Yan, Haiting; Meng, Lingjie; Wei, Zhiyi

2018-06-01

In this work, we fabricate the Mo 0.5 W 0.5 S 2 by microwave-assisted solvothermal method, and report the Q-switched Yb-doped fiber lasers (YDFL) using Mo 0.5 W 0.5 S 2 polymer film and tapered fiber as the saturable absorbers (SAs). The modulation depth and saturable intensity of the film SA are 5.63% and 6.82 MW cm -2 . The shortest pulse duration and the maximum single pulse energy are 1.22 μs and 148.8 nJ for the film SA, 1.46 μs and 339 nJ for the fiber-taper SA. To the best of our knowledge, this is the first report on the Q-switched YDFL using Mo 0.5 W 0.5 S 2 SAs.

Mo0.5W0.5S2 for Q-switched pulse generation in ytterbium-doped fiber laser

NASA Astrophysics Data System (ADS)

Wang, Junli; Chen, Lei; Dou, Chenxi; Yan, Haiting; Meng, Lingjie; Wei, Zhiyi

2018-06-01

In this work, we fabricate the Mo0.5W0.5S2 by microwave-assisted solvothermal method, and report the Q-switched Yb-doped fiber lasers (YDFL) using Mo0.5W0.5S2 polymer film and tapered fiber as the saturable absorbers (SAs). The modulation depth and saturable intensity of the film SA are 5.63% and 6.82 MW cm‑2. The shortest pulse duration and the maximum single pulse energy are 1.22 μs and 148.8 nJ for the film SA, 1.46 μs and 339 nJ for the fiber-taper SA. To the best of our knowledge, this is the first report on the Q-switched YDFL using Mo0.5W0.5S2 SAs.

Carbon Nanotube Mode-Locked Thulium Fiber Laser With 200 nm Tuning Range

NASA Astrophysics Data System (ADS)

Meng, Yafei; Li, Yao; Xu, Yongbing; Wang, Fengqiu

2017-03-01

We demonstrated a mode-locked thulium/holmium (Tm/Ho) fiber laser continuously tunable across 200 nm (from 1860 nm to 2060 nm), which to the best of our knowledge represents the widest tuning range ever achieved for a passively mode-locked fiber laser oscillator. The combined use of a broadband carbon nanotube (CNT) saturable absorber and a diffraction grating mirror ensures ultra-broad tuning range, superb stability and repeatability, and makes the demonstrated laser a highly practical source for spectroscopy, imaging and optical communications. The laser emits <5 ps pulses with an optical spectral bandwidth of ˜3 nm across the full tuning range. Our results indicate that carbon nanotubes can be an excellent saturable absorber for achieving gain-bandwidth-limited tunable operation for 2 μm thulium fiber lasers.

Multi-gigahertz repetition rate passively modelocked fiber lasers using carbon nanotubes.

PubMed

Martinez, Amos; Yamashita, Shinji

2011-03-28

There is an increasing demand for all-fiber passively mode-locked lasers with pulse repetition rates in the order of gigahertz for their potential applications in fields such as telecommunications and metrology. However, conventional mode-locked fiber lasers typically operate at fundamental repetition rates of only a few megahertz. In this paper, we report all-fiber laser operation with fundamental repetition rates of 4.24 GHz, 9.63 GHz and 19.45 GHz. This is, to date and to the best of our knowledge, the highest fundamental repetition rate reported for an all-fiber laser. The laser operation is based on the passive modelocking of a miniature all-fiber Fabry-Pérot laser (FFPL) by a carbon nanotube (CNT) saturable absorber. The key components for such device are a very high-gain Er:Yb phosphosilicate fiber and a fiber compatible saturable absorber with very small foot print and very low losses. The laser output of the three lasers was close to transform-limited with a pulsewidth of approximately 1 ps and low noise. As a demonstration of potential future applications for this laser, we also demonstrated supercontinuum generation with a longitudinal mode-spacing of 0.08 nm by launching the laser operating at 9.63 GHz into 30 m of a highly nonlinear dispersion shifted fiber.

Yb- and Er-doped fiber laser Q-switched with an optically uniform, broadband WS2 saturable absorber

PubMed Central

Zhang, M.; Hu, Guohua; Hu, Guoqing; Howe, R. C. T.; Chen, L.; Zheng, Z.; Hasan, T.

2015-01-01

We demonstrate a ytterbium (Yb) and an erbium (Er)-doped fiber laser Q-switched by a solution processed, optically uniform, few-layer tungsten disulfide saturable absorber (WS2-SA). Nonlinear optical absorption of the WS2-SA in the sub-bandgap region, attributed to the edge-induced states, is characterized by 3.1% and 4.9% modulation depths with 1.38 and 3.83 MW/cm2 saturation intensities at 1030 and 1558 nm, respectively. By integrating the optically uniform WS2-SA in the Yb- and Er-doped laser cavities, we obtain self-starting Q-switched pulses with microsecond duration and kilohertz repetition rates at 1030 and 1558 nm. Our work demonstrates broadband sub-bandgap saturable absorption of a single, solution processed WS2-SA, providing new potential efficacy for WS2 in ultrafast photonic applications. PMID:26657601

Interaction of a parabolic-shaped pulse pair in a passively mode-locked Yb-doped fiber laser

NASA Astrophysics Data System (ADS)

Wang, Da-Shuai; Wu, Ge; Gao, Bo; Tian, Xiao-Jian

2013-01-01

We numerically investigate the formation and interaction of a parabolic-shaped pulse pair in a passively mode-locked Yb-doped fiber laser. Based on a lumped model, the parabolic-shaped pulse pair is obtained by controlling the inter-cavity average dispersion and gain saturation energy, Moreover, pulse repulsive and attractive motion are also achieved with different pulse separations. Simulation results show that the phase shift plays an important role in pulse interaction, and the interaction is determined by the inter-cavity average dispersion and gain saturation energy, i.e., the strength of the interaction is proportional to the gain saturation energy, a stronger gain saturation energy will result in a higher interaction intensity. On the contrary, the increase of the inter-cavity dispersion will counterbalance some interaction force. The results also show that the interaction of a parabolic-shaped pulse pair has a larger interaction distance compared to conventional solitons.

Polarization domain wall pulses in a microfiber-based topological insulator fiber laser

PubMed Central

Liu, Jingmin; Li, Xingliang; Zhang, Shumin; Zhang, Han; Yan, Peiguang; Han, Mengmeng; Pang, Zhaoguang; Yang, Zhenjun

2016-01-01

Topological insulators (TIs), are novel two-dimension materials, which can act as effective saturable absorbers (SAs) in a fiber laser. Moreover, based on the evanescent wave interaction, deposition of the TI on microfiber would create an effective SA, which has combined advantages from the strong nonlinear optical response in TI material together with the sufficiently-long-range interaction length in fiber taper. By using this type of TI SA, various scalar solitons have been obtained in fiber lasers. However, a single mode fiber always exhibits birefringence, and hence can support two orthogonal degenerate modes. Here we investigate experimentally the vector characters of a TI SA fiber laser. Using the saturated absorption and the high nonlinearity of the TI SA, a rich variety of dynamic states, including polarization-locked dark pulses and their harmonic mode locked counterparts, polarization-locked noise-like pulses and their harmonic mode locked counterparts, incoherently coupled polarization domain wall pulses, including bright square pulses, bright-dark pulse pairs, dark pulses and bright square pulse-dark pulse pairs are all observed with different pump powers and polarization states. PMID:27381942

Polarization domain wall pulses in a microfiber-based topological insulator fiber laser

NASA Astrophysics Data System (ADS)

Liu, Jingmin; Li, Xingliang; Zhang, Shumin; Zhang, Han; Yan, Peiguang; Han, Mengmeng; Pang, Zhaoguang; Yang, Zhenjun

2016-07-01

Topological insulators (TIs), are novel two-dimension materials, which can act as effective saturable absorbers (SAs) in a fiber laser. Moreover, based on the evanescent wave interaction, deposition of the TI on microfiber would create an effective SA, which has combined advantages from the strong nonlinear optical response in TI material together with the sufficiently-long-range interaction length in fiber taper. By using this type of TI SA, various scalar solitons have been obtained in fiber lasers. However, a single mode fiber always exhibits birefringence, and hence can support two orthogonal degenerate modes. Here we investigate experimentally the vector characters of a TI SA fiber laser. Using the saturated absorption and the high nonlinearity of the TI SA, a rich variety of dynamic states, including polarization-locked dark pulses and their harmonic mode locked counterparts, polarization-locked noise-like pulses and their harmonic mode locked counterparts, incoherently coupled polarization domain wall pulses, including bright square pulses, bright-dark pulse pairs, dark pulses and bright square pulse-dark pulse pairs are all observed with different pump powers and polarization states.

All-fiber mode-locked laser via short single-wall carbon nanotubes interacting with evanescent wave in photonic crystal fiber.

PubMed

Li, Yujia; Gao, Lei; Huang, Wei; Gao, Cong; Liu, Min; Zhu, Tao

2016-10-03

We report an all-fiber passively mode-locked laser based on a saturable absorber fabricated by filling short single-wall carbon nanotubes into cladding holes of grapefruit-type photonic crystal fiber. The single-wall carbon nanotube is insensitive to polarization of light for its one-dimensional structure, which suppresses the polarization dependence loss. Carbon nanotubes interact with photonic crystal fiber with ultra-weak evanescent field, which enhances the damage threshold of the saturable absorber and improves the operating stability. In our experiment, conventional soliton with a pulse duration of 1.003 ps and center wavelength of 1566.36 nm under a pump power of 240 mW is generated in a compact erbium-doped fiber laser cavity with net anomalous dispersion of -0.4102 ps². The signal to noise ratio of the fundamental frequency component is ~80 dB. The maximum average output power of the mode-locked laser reaches 9.56 mW under a pump power of 360 mW. The output power can be further improved by a higher pump power.

300-MHz-repetition-rate, all-fiber, femtosecond laser mode-locked by planar lightwave circuit-based saturable absorber.

PubMed

Kim, Chur; Kim, Dohyun; Cheong, YeonJoon; Kwon, Dohyeon; Choi, Sun Young; Jeong, Hwanseong; Cha, Sang Jun; Lee, Jeong-Woo; Yeom, Dong-Il; Rotermund, Fabian; Kim, Jungwon

2015-10-05

We show the implementation of fiber-pigtailed, evanescent-field-interacting, single-walled carbon nanotube (CNT)-based saturable absorbers (SAs) using standard planar lightwave circuit (PLC) fabrication processes. The implemented PLC-CNT-SA device is employed to realize self-starting, high-repetition-rate, all-fiber ring oscillators at telecommunication wavelength. We demonstrate all-fiber Er ring lasers operating at 303-MHz (soliton regime) and 274-MHz (stretched-pulse regime) repetition-rates. The 303-MHz (274-MHz) laser centered at 1555 nm (1550 nm) provides 7.5 nm (19 nm) spectral bandwidth. After extra-cavity amplilfication, the amplified pulse train of the 303-MHz (274-MHz) laser delivers 209 fs (178 fs) pulses. To our knowledge, this corresponds to the highest repetition-rates achieved for femtosecond lasers employing evanescent-field-interacting SAs. The demonstrated SA fabrication method, which is based on well-established PLC processes, also shows a potential way for mass-producible and lower-cost waveguide-type SA devices suitable for all-fiber and waveguide lasers.

Carbon Nanotube-Poly(vinylalcohol) Nanocomposite Film Devices: Applications for Femtosecond Fiber Laser Mode Lockers and Optical Amplifier Noise Suppressors

NASA Astrophysics Data System (ADS)

Sakakibara, Youichi; Rozhin, Aleksey G.; Kataura, Hiromichi; Achiba, Yohji; Tokumoto, Madoka

2005-04-01

We fabricated single-wall carbon nanotube (SWNT)/poly(vinylalcohol) (PVA) nanocomposite freestanding films and examined their application in devices in which the saturable absorption of SWNTs at near-infrared optical telecommunication wavelengths can be utilized. In a passively mode-locked fiber laser, we integrated a 30-μm-thick SWNT/PVA film into a fiber connection adaptor with the film sandwiched by a pair of fiber ferrules. A ring fiber laser with a SWNT/PVA saturable absorber was operated very easily in the mode-locked short-pulse mode with a pulse width of about 500 fs. Reproducible stable device performance was confirmed. In examining noise suppression for optical amplifiers, mixed light of semiconductor amplified spontaneous emission (ASE) source and 370 fs laser pulses was passed through a 100-μm-thick SWNT/PVA film. The transmission loss of the femtosecond pulse light was smaller than that of the ASE light. This proved that the SWNT/PVA film has the ability to suppress ASE noise.

Extreme Magneto-transport of Bulk Carbon Nanotubes in Sorted Electronic Concentrations and Aligned High Performance Fiber.

PubMed

Bulmer, John S; Lekawa-Raus, Agnieszka; Rickel, Dwight G; Balakirev, Fedor F; Koziol, Krzysztof K

2017-09-22

We explored high-field (60 T) magneto-resistance (MR) with two carbon nanotube (CNT) material classes: (1) unaligned single-wall CNTs (SWCNT) films with controlled metallic SWCNT concentrations and doping degree and (2) CNT fiber with aligned, long-length microstructure. All unaligned SWCNT films showed localized hopping transport where high-field MR saturation definitively supports spin polarization instead of a more prevalent wave function shrinking mechanism. Nitric acid exposure induced an insulator to metal transition and reduced the positive MR component. Aligned CNT fiber, already on the metal side of the insulator to metal transition, had positive MR without saturation and was assigned to classical MR involving electronic mobility. Subtracting high-field fits from the aligned fiber's MR yielded an unconfounded negative MR, which was assigned to weak localization. It is concluded that fluctuation induced tunnelling, an extrinsic transport model accounting for most of the aligned fiber's room temperature resistance, appears to lack MR field dependence.

Semiconductor saturable absorber mirror passively Q-switched 2.97 μm fluoride fiber laser

NASA Astrophysics Data System (ADS)

Li, Jianfeng; Luo, Hongyu; He, Yulian; Liu, Yong; Luo, Binbin; Sun, Zhongyuan; Zhang, Lin; Turitsyn, Sergei K.

2014-05-01

A diode-cladding-pumped mid-infrared passively Q-switched Ho3+-doped fluoride fiber laser using a reverse designed broad band semiconductor saturable mirror (SESAM) was demonstrated. Nonlinear reflectivity of the SESAM was measured using an in-house Yb3+-doped mode-locked fiber laser at 1062 nm. Stable pulse train was produced at a slope efficient of 12.1% with respect to the launched pump power. Maximum pulse energy of 6.65 μJ with a pulse width of 1.68 μs and signal to noise ratio (SNR) of ~50 dB was achieved at a repetition rate of 47.6 kHz and center wavelength of 2.971 μm. To the best of our knowledge, this is the first 3 μm region SESAM based Q-switched fiber laser with the highest average power and pulse energy, as well as the longest wavelength from mid-infrared passively Q-switched fluoride fiber lasers.

Semiconductor saturable absorber mirror passively Q-switched 2.97 μm fluoride fiber laser

NASA Astrophysics Data System (ADS)

Li, J. F.; Luo, H. Y.; He, Y. L.; Liu, Y.; Zhang, L.; Zhou, K. M.; Rozhin, A. G.; Turistyn, S. K.

2014-06-01

A diode-cladding-pumped mid-infrared passively Q-switched Ho3+-doped fluoride fiber laser using a reverse designed broad band semiconductor saturable mirror (SESAM) was demonstrated. Nonlinear reflectivity of the SESAM was measured using an in-house Yb3+-doped mode-locked fiber laser at 1062 nm. Stable pulse train was produced at a slope efficient of 12.1% with respect to the launched pump power. Maximum pulse energy of 6.65 µJ with a pulse width of 1.68 µs and signal-to-noise ratio (SNR) of ~50 dB was achieved at a repetition rate of 47.6 kHz and center wavelength of 2.971 µm. To the best of our knowledge, this is the first 3 µm region SESAM-based Q-switched fiber laser with the highest average power and pulse energy, as well as the longest wavelength from mid-infrared passively Q-switched fluoride fiber lasers.

Effects of adding metals to MoS2 in a ytterbium doped Q-switched fiber laser

NASA Astrophysics Data System (ADS)

Khaleque, Abdul; Liu, Liming

2018-03-01

Molybdenum disulfide (MoS2) is widely used in lubricants, metallic alloys and in electronic and optical components. It is also used as saturable absorbers (SAs) in lasers (e.g. fiber lasers): a simple deposition of MoS2 on the fiber end can create a saturable absorber without the necessity of extensive alignment of the optical beam. In this article, we study the effects of adding different metals (Cr, Au, and Al) to MoS2 in a ytterbium (Yb)-doped Q-switched fiber laser. Experimental results show that the addition of a thin layer of gold and aluminium can reduce pulse durations to about 5.8 μs and 8.5 μs, respectively, compared with pure MoS2 with pulse duration of 12 μs. Experimental analysis of the combined metal and MoS2 based composite SAs can be useful in fiber laser applications where it may also find applications in medical, three dimensional (3D) active imaging and dental applications.

Sub-100 fs pulses from an all-polarization maintaining Yb-fiber oscillator with an anomalous dispersion higher-order-mode fiber.

PubMed

Verhoef, A J; Zhu, L; Israelsen, S Møller; Grüner-Nielsen, L; Unterhuber, A; Kautek, W; Rottwitt, K; Baltuška, A; Fernández, A

2015-10-05

We present an Yb-fiber oscillator with an all-polarization-maintaining cavity with a higher-order-mode fiber for dispersion compensation. The polarization maintaining higher order mode fiber introduces not only negative second order dispersion but also negative third order dispersion in the cavity, in contrast to dispersion compensation schemes used in previous demonstrations of all-polarization maintaining Yb-fiber oscillators. The performance of the saturable absorber mirror modelocked oscillator, that employs a free space scheme for coupling onto the saturable absorber mirror and output coupling, was investigated for different settings of the intracavity dispersion. When the cavity is operated with close to zero net dispersion, highly stable 0.5-nJ pulses externally compressed to sub-100-fs are generated. These are to our knowledge the shortest pulses generated from an all-polarization-maintaining Yb-fiber oscillator. The spectral phase of the output pulses is well behaved and can be compensated such that wing-free Fourier transform limited pulses can be obtained. Further reduction of the net intracavity third order dispersion will allow generating broader output spectra and consequently shorter pulses, without sacrificing pulse fidelity.

Repetition frequency scaling of an all-polarization maintaining erbium-doped mode-locked fiber laser based on carbon nanotubes saturable absorber

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

Sotor, J., E-mail: jaroslaw.sotor@pwr.edu.pl; Sobon, G.; Abramski, K. M.

We demonstrate an all-polarization maintaining (PM), mode-locked erbium (Er)-doped fiber laser based on a carbon nanotubes (CNT) saturable absorber (SA). The laser resonator was maximally simplified by using only one passive hybrid component and a pair of fiber connectors with deposited CNTs. The repetition frequency (F{sub rep}) of such a cost-effective and self-starting mode-locked laser was scaled from 54.3 MHz to 358.6 MHz. The highest F{sub rep} was obtained when the total cavity length was shortened to 57 cm. The laser allows ultrashort pulse generation with the duration ranging from 240 fs to 550 fs. Because the laser components were based on PMmore » fibers the laser was immune to the external perturbations and generated laniary polarized light with the degree of polarization (DOP) of 98.7%.« less

Accurate determination of fiber water-retaining capability at process conditions by headspace gas chromatography.

PubMed

Zhang, Shu-Xin; Chai, Xin-Sheng; He, Liang

2016-09-16

This work reports on a method for the accurate determination of fiber water-retaining capability at process conditions by headspace gas chromatography (HS-GC) method. The method was based the HS-GC measurement of water vapor on a set closed vials containing in a given amount pulp with different amounts of water addition, from under-saturation to over-saturation. By plotting the equilibrated water vapor signal vs. the amount of water added in pulp, two different trend lines can be observed, in which the transition of the lines corresponds to fiber water-retaining capability. The results showed that the HS-GC method has good measurement precision (much better than the reference method) and good accuracy. The present method can be also used for determining pulp fiber water-retaining capability at the process temperatures in both laboratory research and mill applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Tunable Q-switched erbium doped fiber laser based on metal transition oxide saturable absorber and refractive index characteristic of multimode interference effects

NASA Astrophysics Data System (ADS)

Mohammed, D. Z.; Khaleel, Wurood Abdulkhaleq; Al-Janabi, A. H.

2017-12-01

Ferro-oxide (Fe3O4) nanoparticles were used as a saturable absorber (SA) for a passively Q-switched erbium doped fiber laser (EDFL) with ring cavity. The Q-switching operation was achieved at a pump threshold of 80 mW. The proposed fiber laser produces stable pulses train of repetition rate ranging from 25 kHz to 80 kHz as the pump power increases from threshold to 342 mW. The minimum recorded pulse width was 2.7 μs at 342 mW. The C-band tunability operation was performed using single mode-multimode-single mode fiber (SM-MM-SM) structure. The laser exhibited a total tuning range of 7 nm, maximum sensitivity of 106.9 nm, optical signal to noise ratio (OSNR) of 38 dB and 3-dB linewidth of 0.06 nm.

High power passive mode-locked L-band fiber laser based on microfiber topological insulator saturable absorber

NASA Astrophysics Data System (ADS)

Semaan, Georges; Meng, Yichang; Salhi, Mohamed; Niang, Alioune; Guesmi, Khmaies; Luo, Zhi-Chao; Sanchez, Francois

2016-04-01

In this communication, we demonstrate a passive mode-locked Er:Yb co-doped double-clad fiber laser using a tapered microfiber topological insulator (Bi2Se3) saturable absorber (TISA). The topological insulator is drop-casted onto the tapered fiber and optically deposited by optical tweezer effect. We use a ring laser setup including the fabricated TISA. By carefully optimizing the cavity losses and output coupling ratio, the mode-locked laser can operate in L-band with a high average output power. At a maximum pump power of 5 W, we obtain the 91st harmonic mode-locking of soliton bunches with a 3dB spectral bandwidth of 1.06nm, a repetition rate of 640.9 MHz and an average output power of 308mW. As far as we know, this is the highest output power yet reported of a mode-locked fiber laser operating with a TISA.

Transients control in Raman fiber amplifiers

NASA Astrophysics Data System (ADS)

Freitas, Marcio; Givigi, Sidney N., Jr.; Klein, Jackson; Calmon, Luiz C.; de Almeida, Ailson R.

2004-11-01

Raman fiber amplifiers (RFA) are being used in optical transmission communication systems in the recent years due to their advantages in comparison to erbium-doped fiber amplifiers (EDFA). Recently the analysis of RFAs dynamic response and transients control has become important in order to predict the system response to add/drop of channels or cable cuts in optical systems, and avoid impairments caused by the power transients. Fast signal power transients in the surviving channels are caused by the cross-gain saturation effect in RFA and the slope of the gain saturation characteristics determines the steady-state surviving channel power excursion. We are presenting the modeling and analysis of power transients and its control using a pump control method for a single and multi-pump scheme.

Au nanocage/SiO2 saturable absorber for passive Q-switching Yb-doped fiber laser

NASA Astrophysics Data System (ADS)

Bai, Jinxi; Li, Ping; Guo, Lei; Zhang, Baitao; Hu, Qiongyu; Wang, Lili; Liu, Binghai; Chen, Xiaohan

2018-05-01

Au nanocages/SiO2 (Au-NCs/SiO2) with the surface plasmon resonance peak at 1060 nm were fabricated and experimentally exploited as the saturable absorber in an all-fiber passively Q-switched ytterbium-doped fiber laser for the first time. Under a pump power of 440 mW, the average output power of 10.6 mW was obtained with the pulse duration 1.4 µs and the repetition rate of 126.9 kHz at 1060.5 nm with the 3 dB spectral width of 0.131 nm. The results indicate that Au-NCs/SiO2 exhibits the potential for applications in the field of pulse lasers.

Generation of dark solitons in erbium-doped fiber lasers based Sb(2)Te(3) saturable absorbers.

PubMed

Liu, Wenjun; Pang, Lihui; Han, Hainian; Tian, Wenlong; Chen, Hao; Lei, Ming; Yan, Peiguang; Wei, Zhiyi

2015-10-05

Dark solitons, which have better stability in the presence of noise, have potential applications in optical communication and ultrafast optics. In this paper, the dark soliton formation in erbium-doped fiber lasers based Sb(2)Te(3) saturable absorber (SA) is first experimentally demonstrated. The Sb(2)Te(3) SA is fabricated by using the pulsed laser deposition method. The generated dark solitons are centered at the wavelength of 1530 nm and repetition rate of 94 MHz. Analytic solutions for dark solitons are also obtained theoretically.

All-polarization maintaining erbium fiber laser based on carbon nanowalls saturable absorber

NASA Astrophysics Data System (ADS)

Kurata, Shintaro; Izawa, Jun; Kawaguchi, Norihito

2018-02-01

We report a soliton mode locked femtosecond oscillation with all-polarization maintaining erbuim doped fiber laser based on Carbon Nanowalls saturable absorber (CNWs SA). To improve the stability and the capability of the oscillator, the all-polarization maintaining(all-PM) fiber is generally used since PM fiber is tolerant of stretches and bends. The saturable absorber is an optical device that placed in a laser cavity to suppress continuous wave operation to promote cooperation between many modes to sustain ultrashort pulse operation. We apply CNWs for the material of SAs in our oscillator. CNWs are one of the nanocarbon materials, which are a high-aspect-ratio structure in the cross-section, where, although their width and height range in a few micrometers, the thickness is as small as ten nanometers or so. A sheet of CNWs is made up of nano-size graphite grain aggregates. Then CNWs structure is expected to have a high absorption to the incident light and large modulation depth due to a small number of carbon layers as well as CNT and Graphene. With this all-PM fiber laser oscillator based on CNWs SA, the soliton mode-locked laser oscillated with 66.3MHz repetition frequency and its spectrum width is 5.6nm in FWHM. Average output power is 8.1mW with 122.5mW laser diode pump power. In addition, the laser amplification system with erbium-doped fiber is constructed and amplifies the femtosecond pulse laser into 268.2mW and 3000mW pumping power.

CNT-based saturable absorbers with scalable modulation depth for Thulium-doped fiber lasers operating at 1.9 μm

PubMed Central

Sobon, Grzegorz; Duzynska, Anna; Świniarski, Michał; Judek, Jarosław; Sotor, Jarosław; Zdrojek, Mariusz

2017-01-01

In this work, we demonstrate a comprehensive study on the nonlinear parameters of carbon nanotube (CNT) saturable absorbers (SA) as a function of the nanotube film thickness. We have fabricated a set of four saturable absorbers with different CNT thickness, ranging from 50 to 200 nm. The CNTs were fabricated via a vacuum filtration technique and deposited on fiber connector end facets. Each SA was characterized in terms of nonlinear transmittance (i.e. optical modulation depth) and tested in a Thulium-doped fiber laser. We show, that increasing the thickness of the CNT layer significantly increases the modulation depth (up to 17.3% with 200 nm thick layer), which strongly influences the central wavelength of the laser, but moderately affects the pulse duration. It means, that choosing the SA with defined CNT thickness might be an efficient method for wavelength-tuning of the laser, without degrading the pulse duration. In our setup, the best performance in terms of bandwidth and pulse duration (8.5 nm and 501 fs, respectively) were obtained with 100 nm thick CNT layer. This is also, to our knowledge, the first demonstration of a fully polarization-maintaining mode-locked Tm-doped laser based on CNT saturable absorber. PMID:28368014

Optical fiber probe spectroscopy for laparoscopic monitoring of tissue oxygenation during esophagectomies

NASA Astrophysics Data System (ADS)

Gareau, Daniel S.; Truffer, Frederic; Perry, Kyle; Pham, Thai; Enestvedt, C. Kristian; Dolan, James; Hunter, John G.; Jacques, Steven L.

2010-11-01

Anastomotic complication is a major morbidity associated with esophagectomy. Gastric ischemia after conduit creation contributes to anastomotic complications, but a reliable method to assess oxygenation in the gastric conduit is lacking. We hypothesize that fiber optic spectroscopy can reliably assess conduit oxygenation, and that intraoperative gastric ischemia will correlate with the development of anastomotic complications. A simple optical fiber probe spectrometer is designed for nondestructive laparoscopic measurement of blood content and hemoglobin oxygen saturation in the stomach tissue microvasculature during human esophagectomies. In 22 patients, the probe measured the light transport in stomach tissue between two fibers spaced 3-mm apart (500- to 650-nm wavelength range). The stomach tissue site of measurement becomes the site of a gastroesophageal anastamosis following excision of the cancerous esophagus and surgical ligation of two of the three gastric arteries that provide blood perfusion to the anastamosis. Measurements are made at each of five steps throughout the surgery. The resting baseline saturation is 0.51+/-0.15 and decreases to 0.35+/-0.20 with ligation. Seven patients develop anastomotic complications, and a decreased saturation at either of the last two steps (completion of conduit and completion of anastamosis) is predictive of complication with a sensitivity of 0.71 when the specificity equaled 0.71.

Mode-locked Er-doped fiber laser based on PbS/CdS core/shell quantum dots as saturable absorber.

PubMed

Ming, Na; Tao, Shina; Yang, Wenqing; Chen, Qingyun; Sun, Ruyi; Wang, Chang; Wang, Shuyun; Man, Baoyuan; Zhang, Huanian

2018-04-02

Previously, PbS/CdS core/shell quantum dots with excellent optical properties have been widely used as light-harvesting materials in solar cell and biomarkers in bio-medicine. However, the nonlinear absorption characteristics of PbS/CdS core/shell quantum dots have been rarely investigated. In this work, PbS/CdS core/shell quantum dots were successfully employed as nonlinear saturable absorber (SA) for demonstrating a mode-locked Er-doped fiber laser. Based on a film-type SA, which was prepared by incorporating the quantum dots with the polyvinyl alcohol (PVA), mode-locked Er-doped operation with a pulse width of 54 ps and a maximum average output power of 2.71 mW at the repetition rate of 3.302 MHz was obtained. Our long-time stable results indicate that the CdS shell can effectively protect the PbS core from the effect of photo-oxidation and PbS/CdS core/shell quantum dots were efficient SA candidates for demonstrating pulse fiber lasers due to its tunable absorption peak and excellent saturable absorption properties.

Coherent chirped pulse laser network with Mickelson phase conjugator.

PubMed

Okulov, A Yu

2014-04-10

The mechanisms of nonlinear phase-locking of a large fiber amplifier array are analyzed. The preference is given to the most suitable configuration for a coherent coupling of thousands of fundamental spatial mode fiber beams into a single smooth beam ready for chirped pulse compression. It is shown that a Michelson phase-conjugating configuration with double passage through an array of fiber amplifiers has the definite advantage compared to a one-way fiber array coupled in a Mach-Zehnder configuration. Regardless of the amount of synchronized fiber amplifiers, the Michelson phase-conjugating interferometer is expected to do a perfect compensation of the phase-piston errors and collimation of backwardly amplified fiber beams on an entrance/output beam splitter. In both configurations, the nonlinear transformation of the stretched pulse envelope, due to gain saturation, is capable of randomizing the position of chirp inside an envelope; thus it may reduce the visibility of the interference pattern at an output beam splitter. Certain advantages are inherent to the sech-form temporal envelope because of the exponential precursor and self-similar propagation in gain medium. The Gaussian envelope is significantly compressed in a deep gain saturation regime, and the frequency chirp position inside pulse envelope is more deformed.

Is the wall of a cellulose fiber saturated with liquid whether or not permeable with CO2 dissolved molecules? Application to bubble nucleation in champagne wines.

PubMed

Liger-Belair, Gérard; Topgaard, Daniel; Voisin, Cédric; Jeandet, Philippe

2004-05-11

In this paper, the transversal diffusion coefficient D perpendicular of CO2 dissolved molecules through the wall of a hydrated cellulose fiber was approached, from the liquid bulk diffusion coefficient of CO2 dissolved molecules modified by an obstruction factor. The porous network between the cellulose microfibrils of the fiber wall was assumed being saturated with liquid. We retrieved information from previous NMR experiments on the self-diffusion of water in cellulose fibers to reach an order of magnitude for the transversal diffusion coefficient of CO2 molecules through the fiber wall. A value of about D perpendicular approximately 0.2D0 was proposed, D0 being the diffusion coefficient of CO2 molecules in the liquid bulk. Because most of bubble nucleation sites in a glass poured with carbonated beverage are cellulose fibers cast off from paper or cloth which floated from the surrounding air, or remaining from the wiping process, this result directly applies to the kinetics of carbon dioxide bubble formation from champagne and sparkling wines. If the cellulose fiber wall was impermeable with regard to CO2 dissolved molecules, it was suggested that the kinetics of bubbling would be about three times less than it is.

1.6 μm dissipative soliton fiber laser mode-locked by cesium lead halide perovskite quantum dots.

PubMed

Liu, Bang; Gao, Lei; Cheng, Wei Wei; Tang, Xiao Sheng; Gao, Chao; Cao, Yu Long; Li, Yu Jia; Zhu, Tao

2018-03-19

We demonstrate a stable, picosecond fiber laser mode-locked by cesium lead halide perovskite quantum dots (CsPbBr 3 -QDs). The saturable absorber is produced by depositing the CsPbBr3-QDs nanocrystals onto the endface of a fiber ferrule through light pressure. A balanced two-detector measurement shows that it has a modulation depth of 2.5% and a saturation power of 17.29 MW/cm 2 . After incorporating the fabricated device into an Er 3+ -doped fiber ring cavity with a net normal dispersion of 0.238 ps 2 , we obtain stable dissipative soliton with a pulse duration of 14.4 ps and a center wavelength at 1600 nm together with an edge-to-dege bandwidth of 4.5 nm. The linear chirped phase can be compensated by 25 m single mode fiber, resulting into a compressed pulse duration of 1.046 ps. This experimental works proves that such CsPbBr3-QDs materials are effective choice for ultrafast laser operating with devious mode-locking states.

Stable optical soliton in the ring-cavity fiber system with carbon nanotube as saturable absorber

NASA Astrophysics Data System (ADS)

Li, Bang-Qing; Ma, Yu-Lan; Yang, Tie-Mei

2018-01-01

Main attention focuses on the theoretical study of the ring-cavity fiber laser system with carbon nanotubes (CNT) as saturable absorber (SA). The system is modelled as a non-standard Schrödinger equation with the coefficients blended real and imaginary numbers. New stable exact soliton solution is constructed by the bilinear transformation method for the system. The influences of the key parameters related to CNTs and SA on the optical pulse soliton are discussed in simulation. The soliton amplitude and phase can be tuned by choosing suitable parameters.

Wavelength-tunable, passively mode-locked fiber laser based on graphene and chirped fiber Bragg grating.

PubMed

He, Xiaoying; Liu, Zhi-bo; Wang, D N

2012-06-15

We demonstrate a wavelength-tunable, passively mode-locked erbium-doped fiber laser based on graphene and chirped fiber Bragg grating. The saturable absorber used to enable passive mode-locking in the fiber laser is a section of microfiber covered by graphene film, which allows light-graphene interaction via the evanescent field of the microfiber. The wavelength of the laser can be continuously tuned by adjusting the chirped fiber Bragg grating, while maintaining mode-locking stability. Such a system has high potential in tuning the mode-locked laser pulses across a wide wavelength range.

Dual-wavelength passively Q-switched ytterbium-doped fiber laser using Fe3O4-nanoparticle saturable absorber and intracavity polarization

NASA Astrophysics Data System (ADS)

Al-Hayali, S. K. M.; Al-Janabi, A. H.

2018-03-01

We have experimentally demonstrated the operation of a dual-wavelength passively Q-switched ytterbium-doped fiber laser by using a saturable absorber (SA) based on Fe3O4 nanoparticles in a magnetic fluid. The SA was fabricated by depositing magnetic fluid at the end of an optical fiber ferrule. By performing adjustments to the pump power and polarization controller state in the cavity, a stable dual-wavelength lasing operation was generated without intracavity spectral filters or modulation elements. The Q-switched laser output was achieved at a pump threshold of 80 mW with a maximum output pulse energy of 38.8 nJ, a repetition rate of 73.4 kHz and a minimum pulse width of 3.4 µs. To the best of the authors’ knowledge, this is the first demonstration of a dual-wavelength passively Q-switched fiber laser using Fe3O4 nanoparticles as the SA in the 1.0 µm operation region.

The picosecond structure of ultra-fast rogue waves

NASA Astrophysics Data System (ADS)

Klein, Avi; Shahal, Shir; Masri, Gilad; Duadi, Hamootal; Sulimani, Kfir; Lib, Ohad; Steinberg, Hadar; Kolpakov, Stanislav A.; Fridman, Moti

2018-02-01

We investigated ultrafast rogue waves in fiber lasers and found three different patterns of rogue waves: single- peaks, twin-peaks, and triple-peaks. The statistics of the different patterns as a function of the pump power of the laser reveals that the probability for all rogue waves patterns increase close to the laser threshold. We developed a numerical model which prove that the ultrafast rogue waves patterns result from both the polarization mode dispersion in the fiber and the non-instantaneous nature of the saturable absorber. This discovery reveals that there are three different types of rogue waves in fiber lasers: slow, fast, and ultrafast, which relate to three different time-scales and are governed by three different sets of equations: the laser rate equations, the nonlinear Schrodinger equation, and the saturable absorber equations, accordingly. This discovery is highly important for analyzing rogue waves and other extreme events in fiber lasers and can lead to realizing types of rogue waves which were not possible so far such as triangular rogue waves.

Short pulse fiber lasers mode-locked by carbon nanotubes and graphene

NASA Astrophysics Data System (ADS)

Yamashita, Shinji; Martinez, Amos; Xu, Bo

2014-12-01

One and two dimensional forms of carbon, carbon nanotubes and graphene, have interesting and useful, not only electronic but also photonic, properties. For fiber lasers, they are very attractive passive mode lockers for ultra-short pulse generation, since they have saturable absorption with inherently fast recovery time (<1 ps). In this paper, we review the photonic properties of graphene and CNT and our recent works on fabrication of fiber devices and applications to ultra-short pulse mode-locked fiber lasers.

Saturable absorber Q- and gain-switched all-Yb3+ all-fiber laser at 976 and 1064 nm.

PubMed

Tsai, Tzong-Yow; Fang, Yen-Cheng; Huang, Huai-Min; Tsao, Hong-Xi; Lin, Shih-Ting

2010-11-08

We demonstrate a novel passively pulsed all-Yb3+ all-fiber laser pumped by a continuous-wave 915-nm pump laser diode. The laser was saturable absorber Q-switched at 976 nm and gain-switched at 1064 nm, using the method of mode-field-area mismatch. With a pump power of 
105 mW, the laser iteratively produced a 976-nm pulse with an energy of 2.8 μJ and a duration of 280 ns, followed by a 1064-nm pulse with 1.1 μJ and a 430-ns duration at a repetition rate of 9 kHz. A set of rate equations was established to simulate the self-balancing mechanism and the correlation between the Q- and gain-switched photon numbers and the populations of the gain and absorber fibers.

Scintillation probe with photomultiplier tube saturation indicator

DOEpatents

Ruch, Jeffrey F.; Urban, David J.

1996-01-01

A photomultiplier tube saturation indicator is formed by supplying a supplemental light source, typically an light emitting diode (LED), adjacent to the photomultiplier tube. A switch allows the light source to be activated. The light is forwarded to the photomultiplier tube by an optical fiber. If the probe is properly light tight, then a meter attached to the indicator will register the light from the LED. If the probe is no longer light tight, and the saturation indicator is saturated, no signal will be registered when the LED is activated.

An 8 cm long holmium-doped fiber saturable absorber for Q-switched fiber laser generation at 2-μm region

NASA Astrophysics Data System (ADS)

Rahman, M. F. A.; Dhar, A.; Das, S.; Dutta, D.; Paul, M. C.; Rusdi, M. F. M.; Latiff, A. A.; Dimyati, K.; Harun, S. W.

2018-07-01

We demonstrate a Q-switched all-fiber laser operating at 2-μm region by adding a piece of 8 cm long holmium doped fiber (HDF) as a fiber saturable absorber (SA) in Thulium doped fiber laser (TDFL) ring cavity. Doping of Ho ions into yttria-alumina silica glass was done through conventional Modified Chemical Vapor Deposition (MCVD) technique in conjunction with solution doping process. The fabricated HDF has a linear absorption of 3 dB with a core diameter and a numerical aperture of 10 μm and 0.18, respectively. A self-started Q-switching operation begins at 418 mW pump level and continually dominant until 564 mW pump level. As the pump power increases, stable pulse train presence from 30.61 kHz to 38.89 kHz while the pulse width reduces from 3.18 μs to 2.27 μs. Both maximum output power and maximum peak power are obtained at 5.05 mW and 57.2 mW, respectively, while the maximum pulse energy is calculated to be 129 nJ. The signal-to-noise ratio (SNR) of the fundamental frequency is 50 dB. Our work may contribute to the discovery of stable, robust, and economic SA for pulse fiber laser generation at 2-μm region.

Ultra-broadband nonlinear saturable absorption of high-yield MoS2 nanosheets

NASA Astrophysics Data System (ADS)

Wei, Rongfei; Zhang, Hang; Hu, Zhongliang; Qiao, Tian; He, Xin; Guo, Qiangbing; Tian, Xiangling; Chen, Zhi; Qiu, Jianrong

2016-07-01

High-yield MoS2 nanosheets with strong nonlinear optical (NLO) responses in a broad near-infrared range were synthesized by a facile hydrothermal method. The observation of saturable absorption, which was excited by the light with photon energy smaller than the gap energy of MoS2, can be attributed to the enhancement of the hybridization between the Mo d-orbital and S p-orbital by the oxygen incorporation into MoS2. High-yield MoS2 nanosheets with high modulation depth and large saturable intensity generated a stable, passively Q-switched fiber laser pulse at 1.56 μm. The high output power of 1.08 mW can be attained under a very low pump power of 30.87 mW. Compared to recently reported passively Q-switched fiber lasers utilizing exfoliated MoS2 nanosheets, the efficiency of the laser for our passive Q-switching operation is larger and reaches 3.50%. This research may extend the understanding on the NLO properties of MoS2 and indicate the feasibility of the high-yield MoS2 nanosheets to passively Q-switched fiber laser effectively at low pump strengths.

CsPbBr3 nanocrystal saturable absorber for mode-locking ytterbium fiber laser

NASA Astrophysics Data System (ADS)

Zhou, Yan; Hu, Zhiping; Li, Yue; Xu, Jianqiu; Tang, Xiaosheng; Tang, Yulong

2016-06-01

Cesium lead halide perovskite nanocrystals (CsPbX3, X = Cl, Br, I) have been reported as efficient light-harvesting and light-emitting semiconductor materials, but their nonlinear optical properties have been seldom touched upon. In this paper, we prepare layered CsPbBr3 nanocrystal films and characterize their physical properties. Broadband linear absorption from ˜0.8 to over 2.2 μm and nonlinear optical absorption at the 1-μm wavelength region are measured. The CsPbBr3 saturable absorber (SA), manufactured by drop-casting of colloidal CsPbBr3 liquid solution on a gold mirror, shows modulation depth and saturation intensity of 13.1% and 10.7 MW/cm2, respectively. With this SA, mode-locking operation of a polarization-maintained ytterbium fiber laser produces single pulses with duration of ˜216 ps, maximum average output power of 10.5 mW, and the laser spectrum is centered at ˜1076 nm. This work shows that CsPbBr3 films can be efficient SA candidates for fiber lasers and also have great potential to become broadband linear and nonlinear optical materials for photonics and optoelectronics.

Vector dissipative solitons in graphene mode locked fiber lasers

NASA Astrophysics Data System (ADS)

Zhang, Han; Tang, Dingyuan; Zhao, Luming; Bao, Qiaoliang; Loh, Kian Ping

2010-09-01

Vector soliton operation of erbium-doped fiber lasers mode locked with atomic layer graphene was experimentally investigated. Either the polarization rotation or polarization locked vector dissipative solitons were experimentally obtained in a dispersion-managed cavity fiber laser with large net cavity dispersion, while in the anomalous dispersion cavity fiber laser, the phase locked nonlinear Schrödinger equation (NLSE) solitons and induced NLSE soliton were experimentally observed. The vector soliton operation of the fiber lasers unambiguously confirms the polarization insensitive saturable absorption of the atomic layer graphene when the light is incident perpendicular to its 2-dimentional (2D) atomic layer.

Influence of the UV-induced fiber loss on the distributed feedback fiber lasers

NASA Astrophysics Data System (ADS)

Fan, Wei; Chen, Bai; Qiao, Qiquan; Chen, Jialing; Lin, Zunqi

2003-06-01

It was found that the output power of the distributed feedback fiber lasers would be improved after annealing or left unused for several days after the laser had been fabricated, and the output of the fundamental mode would not increase but be clamped while the ±1 order modes would be predominant with the enhancement of the coupling coefficient during the fabrication. The paper discussed the influence of UV-induced fiber loss on the fiber phase-shifted DFB lasers. Due to the gain saturation and fiber internal loss, which included the temperament loss and permanent loss, there was an optimum coupling coefficient for the DFB fiber lasers that the higher internal fiber loss corresponded to the lower optimum values of coupling coefficient.

Efficient graphene saturable absorbers on D-shaped optical fiber for ultrashort pulse generation

PubMed Central

Zapata, J. D.; Steinberg, D.; Saito, L. A. M.; de Oliveira, R. E. P.; Cárdenas, A. M.; de Souza, E. A. Thoroh

2016-01-01

We demonstrated a method to construct high efficiency saturable absorbers based on the evanescent light field interaction of CVD monolayer graphene deposited on side-polished D-shaped optical fiber. A set of samples was fabricated with two different core-graphene distances (0 and 1 μm), covered with graphene ranging between 10 and 25 mm length. The mode-locking was achieved and the best pulse duration was 256 fs, the shortest pulse reported in the literature with CVD monolayer graphene in EDFL. As result, we find a criterion between the polarization relative extinction ratio in the samples and the pulse duration, which relates the better mode-locking performance with the higher polarization extinction ratio of the samples. This criterion also provides a better understanding of the graphene distributed saturable absorbers and their reproducible performance as optoelectronic devices for optical applications. PMID:26856886

Phosphorene quantum dot saturable absorbers for ultrafast fiber lasers

PubMed Central

Du, J.; Zhang, M.; Guo, Z.; Chen, J.; Zhu, X.; Hu, G.; Peng, P.; Zheng, Z.; Zhang, H.

2017-01-01

We fabricate ultrasmall phosphorene quantum dots (PQDs) with an average size of 2.6 ± 0.9 nm using a liquid exfoliation method involving ultrasound probe sonication followed by bath sonication. By coupling the as-prepared PQDs with microfiber evanescent light field, the PQD-based saturable absorber (SA) device exhibits ultrafast nonlinear saturable absorption property, with an optical modulation depth of 8.1% at the telecommunication band. With the integration of the all-fiber PQD-based SA, a continuous-wave passively mode-locked erbium-doped (Er-doped) laser cavity delivers stable, self-starting pulses with a pulse duration of 0.88 ps and at the cavity repetition rate of 5.47 MHz. Our results contribute to the growing body of work studying the nonlinear optical properties of ultrasmall PQDs that present new opportunities of this two-dimensional (2D) nanomaterial for future ultrafast photonic technologies. PMID:28211471

Transition metal dichalcogenide (WS2 and MoS2) saturable absorbers for Q-switched Er-doped fiber lasers

NASA Astrophysics Data System (ADS)

Li, Lu; Lv, Ruidong; Liu, Sicong; Wang, Xi; Wang, Yonggang; Chen, Zhendong; Wang, Jiang

2018-05-01

This report demonstrates a stable Q-switched Er-doped fiber laser with MoS2 (WS2)-based saturable absorber (SA) in the net normal dispersion regime. The SA is obtained by mixing MoS2 (WS2) nanosheets with polyvinyl alcohol (PVA) into polystyrene cells, and then evaporating them to form MoS2 (WS2)/PVA film. The modulation depth values for MoS2/PVA and WS2/PVA are measured to be 2.7% and 2.1% respectively. Employing the MoS2 (WS2)/PVA film in the Er-doped fiber laser cavity, stable Q-switching operation is achieved with central wavelength of 1560 nm. The shortest pulse durations of the two Q-switched fiber lasers are, respectively, 3.97 and 3.71 µs, and their maximum single pulse energies are measured to be 131.52 and 126.96 nJ. The experimental results clearly show that MoS2 (WS2) is a promising nonlinear material, and that improvements in Q-switching performance due to two SAs in the net normal dispersion regime might be helpful in the design of fiber lasers.

Exploiting nonlinear properties of pure and Sn-doped Bi2Te2Se for passive Q-switching of all-polarization maintaining ytterbium- and erbium-doped fiber lasers.

PubMed

Bogusławski, Jakub; Kowalczyk, Maciej; Iwanowski, Przemysław; Hruban, Andrzej; Diduszko, Ryszard; Piotrowski, Kazimierz; Dybko, Krzysztof; Wojciechowski, Tomasz; Aleszkiewicz, Marta; Sotor, Jarosław

2017-08-07

Due to their broadband nonlinear optical properties, low-dimensional materials are widely used for pulse generation in fiber and solid-state lasers. Here we demonstrate novel materials, Bi 2 Te 2 Se (BTS) and Sn-doped Bi 2 Te 2 Se (BSTS), which can be used as a universal saturable absorbers for distinct spectral regimes. The material was mechanically exfoliated from a bulk single-crystal and deposited onto a side-polished fiber. We have performed characterization of the fabricated devices and employed them in polarization-maintaining ytterbium- and erbium-doped fiber lasers. This enabled us to obtain self-starting passively Q-switched regime at 1 µm and 1.56 µm. The oscillators emitted stable, linearly polarized radiation with the highest single pulse energy approaching 692 nJ. Both lasers are characterized by the best performance observed in all-polarization maintaining Q-switched fiber lasers with recently investigated new saturable absorbers, which was enabled by a very high damage threshold of the devices. This demonstrates the great potential of the investigated materials for the ultrafast photonics community.

Impacts of doping concentration on the saturable characteristics of Tm-Ho codoped fiber saturable absorber

NASA Astrophysics Data System (ADS)

Tao, Mengmeng; Feng, Guobin; Yu, Ting; Ye, Xisheng; Wang, Zhenbao; Shen, Yanlong; Zhao, Jun

2018-03-01

Impacts of Tm ion concentration and Ho ion concentration on the saturable behaviors of Tm-Ho codoped fiber saturable absorbers and the output characteristics of the passively Q-switched laser systems are investigated and analyzed both at the initial lasing state and the stable passive Q-switching state. Simulations show that, varying concentrations of Tm and Ho ions have different impacts on the temporal evolution processes but similar effects on the macroscopic characteristics of the laser system. The root for the impacts of dopant concentrations is the population of the 3H6 energy level and the cavity loss it induces. For Tm ions, the rise of the Tm concentration improves the population of the 3H6 energy level directly, while, for Ho ions, higher Ho concentration leads to larger recovery rate of the 3H6 energy level, thus increasing the population of the 3H6 energy level indirectly. As for limited total dopant concentration, the Tm:Ho concentration ratio can be optimized for different applications.

Silica-coated gold nanorods as saturable absorber for bound-state pulse generation in a fiber laser with near-zero dispersion

NASA Astrophysics Data System (ADS)

Wang, Xude; Luo, Aiping; Luo, Zhichao; Liu, Meng; Zou, Feng; Zhu, Yanfang; Xue, Jianping; Xu, Wencheng

2017-11-01

We presented a bound-state operation in a fiber laser with near-zero anomalous dispersion based on a silica-coated gold nanorods (GNRs@SiO2) saturable absorber (SA). Using a balanced twin detector measurement technique, the modulation depth and nonsaturable loss of the GNRs@SiO2 SA were measured to be approximately 3.5% and 39.3%, respectively. By virtue of the highly nonlinear effect of the GNRs@SiO2 SA, the bound-state pulses could be easily observed. Besides the lower-order bound-state pulses with two, three, and four solitons, the higher-order bound states with up to 12 solitons were also obtained in the laser cavity. The pulse profiles of the higher-order bound states were further reconstructed theoretically. The experimental results would give further insight towards understanding the complex nonlinear dynamics of bound-state pulses in fiber lasers.

Black phosphorus: a two-dimension saturable absorption material for mid-infrared Q-switched and mode-locked fiber lasers

PubMed Central

Li, Jianfeng; Luo, Hongyu; Zhai, Bo; Lu, Rongguo; Guo, Zhinan; Zhang, Han; Liu, Yong

2016-01-01

Black phosphorus (BP) as a novel class of two-dimension (2D) materials has recently attracted enormous attention as a result of its unique physical and chemical features. The remarkably strong light-matter interaction and tunable direct band-gap at a wide range make it an ideal candidate especially in the mid-infrared wavelength region as the saturable absorber (SA). In this paper, the simple and effective liquid phase exfoliation (LPE) method was used to fabricate BP. By introducing the same BP SA into two specifically designed rare earth ions doped fluoride fiber lasers at mid-infrared wavebands, Q-switching with the pulse energy of 4.93 μJ and mode-locking with the pulse duration of 8.6 ps were obtained, respectively. The operation wavelength of ~2970 nm for generated pulse is the reported longest wavelength for BP SA based fiber lasers. PMID:27457338

Gold nanorod as saturable absorber for Q-switched Yb-doped fiber laser

NASA Astrophysics Data System (ADS)

Wang, Xu-De; Luo, Zhi-Chao; Liu, Hao; Zhao, Nian; Liu, Meng; Zhu, Yan-Fang; Xue, Jian-Ping; Luo, Ai-Ping; Xu, Wen-Cheng

2015-07-01

We reported on the generation of Q-switched pulse in an Yb-doped fiber laser by using a filmy polyvinyl alcohol (PVA)-based gold nanorods (GNRs) saturable absorber (SA). The GNRs are synthesized through seed-mediated method whose longitudinal surface plasmon resonance (SPR) absorption peak is located at 1038 nm. The modulation depth of the GNRs SA is ∼4.06%. By gradually increasing the pump power from 62 mW to 128 mW, the repetition rate of Q-switched pulse increases from 8.78 kHz to 20.78 kHz and the pulse duration decreases from 9.43 μs to 3.65 μs. In addition, the dual-wavelength switchable Q-switched operation was also observed. The obtained results further expand the applications of GNRs SA to the field of Q-switched pulsed fiber lasers at 1.0 μm waveband.

Ultrashort pulse generation in mode-locked erbium-doped fiber lasers with tungsten disulfide saturable absorber

NASA Astrophysics Data System (ADS)

Liu, Mengli; Liu, Wenjun; Pang, Lihui; Teng, Hao; Fang, Shaobo; Wei, Zhiyi

2018-01-01

Tungsten disulfide (WS2), as one of typical transition metal dichalcogenides with the characteristics of strong nonlinear polarization and wide bandgap, has been widely used in such fields as biology and optoelectronics. With the magnetron sputtering technique, the saturable absorber (SA) is prepared by depositing WS2 and Au film on the tapered fiber. The heat elimination and damage threshold can be improved for the WS2 SA with evanescent field interaction. Besides, the Au film is deposited on the surface of the WS2 film to improve their reliability and avoid being oxidized. The fabricated SA has a modulation depth of 14.79%. With this SA, we obtain a relatively stable mode-locked fiber laser with the pulse duration of 288 fs, the repetition rate of 41.4 MHz and the signal to noise ratio of 58 dB.

A stable dual-wavelength Q-switch using a compact passive device containing photonics crystal fiber embedded with carbon platinum

NASA Astrophysics Data System (ADS)

Safaei, R.; Amiri, I. S.; Rezayi, M.; Ahmad, H.

2018-01-01

A compact fiber laser utilizing platinum nanoparticles doped on carbon (Pt/C) embedded in photonic crystal fiber capable of generating a stable Q-switch dual-wavelength is designed and verified. Stable Q-switch pulses, with a repetition rate of 73.6 kHz, pulse width of 1.45 µs and power of 3.8 nJ in two separated wavelengths of 1557.39 nm and 1558.86 nm at a pump power of 350 mW, have been obtained. This is a novel method for generating Q-switch dual-wavelength pulses using a well-protected component that introduces both a saturable absorber and Mach-Zehnder interferometer effects simultaneously in the laser cavity. Furthermore, to best of our knowledge, this is the first time that Pt/C nanoparticles have been used in a saturable absorber for optical pulse generation.

Impact of material absorption on supercontinuum generation in liquid core photonic crystal fiber

NASA Astrophysics Data System (ADS)

Nithyanandan, K.; Raja, Vasantha Jayakantha; Uthayakumar, T.; Porsezian, K.

2013-06-01

The impact of material absorption on supercontinuum generation (SCG) in liquid core photonic crystal fiber (LCPCF) is presented. While PCFs with cores made from different glasses are well studied in previous works with saturable nonlinear response (SNL), in this paper, it is planned to investigate the dynamics of nonlinear processes of supercontinuum generation in high-index fiber with material absorption to understand the physical phenomena of pulse propagation.

Acoustoelectric current saturation in c-axis fiber-textured polycrystalline zinc oxide films

NASA Astrophysics Data System (ADS)

Pompe, T.; Srikant, V.; Clarke, D. R.

1996-12-01

Acoustoelectric current saturation, which until now has only been observed in piezoelectric single crystals, is observed in thin polycrystalline zinc oxide films. Epitaxial ZnO films on c-plane sapphire and textured ZnO polycrystalline films on fused silica both exhibit current saturation phenomenon. The values of the saturation current densities are in the range 105-106 A/cm2, depending on the carrier concentration in the film, with corresponding saturation electric fields of 3-5×103 V/cm. In addition to the current saturation, the electrical properties of the films degraded with the onset of the acoustoelectric effect but could be restored by annealing at 250 °C in a vacuum for 30 min.

Utilization of Re-processed Anaerobically Digested Fiber from Dairy Manure as a Container Media Substrate

USDA-ARS?s Scientific Manuscript database

The solid fraction (fiber) from the effluent of the anaerobic digestion of dairy manure by plug flow technology yields material that has consistent physical properties (total porosity, air filled porosity at saturation, and water holding capacity) to perform satisfactorily as a plant growth media su...

Direct Spectroscopy in Hollow Optical with Fiber-Based Optical Frequency Combs

DTIC Science & Technology

2015-07-09

scheme is that the generation of carrier-envelope offset frequency f0 can be avoided, which reduces the system complexity . However, a high performance RF...Peterson, "Saturated absorption in acetylene and hydrogen cyanide in hollow-core photonic bandgap fibers," Opt. Express 13, 10475-10482 (2005). 56. C

Population gratings in saturable optical fibers with randomly oriented rare-earth ions

NASA Astrophysics Data System (ADS)

Stepanov, S.; Martinez, L. M.; Hernandez, E. H.; Agruzov, P.; Shamray, A.

2015-07-01

Formation of the dynamic population gratings in optical fibers with randomly oriented rare-earth ions is analyzed with a special interest to the grating component for readout with the orthogonal light polarization. It is shown that as compared with a simple model case of the collinearly oriented dipole-like centers their random orientation leads to approximately 2-times growth of the effective saturation power P sat when it is estimated from the incident power dependence of the fiber absorption or from that of the fluorescence intensity. An optimal incident power, for which the maximum of the dynamic population grating amplitude for collinear light polarization is observed, also follows this change in P sat, while formation of the grating for orthogonal polarization needs essentially higher light power. The reduced anisotropy of the active centers, which is in charge of the experimentally observed weakening of the polarization hole burning (PHB) and of the fluorescence polarization, compensates in some way the effect of random ion orientation. The ratio between the maximum conventional (i.e. for the interacting waves collinear polarizations) two-wave mixing (TWM) amplitude and the initial not saturable fiber optical density proves to be, however, nearly the same as in the model case of collinearly oriented dipoles. The ratio between the PHB effect and the amplitude of the anisotropic grating, which is responsible for TWM of the orthogonally polarized waves, is also not influenced significantly by the reduced anisotropy of ions.

Nonlinear Saturable and Polarization-induced Absorption of Rhenium Disulfide

PubMed Central

Cui, Yudong; Lu, Feifei; Liu, Xueming

2017-01-01

Monolayer of transition metal dichalcogenides (TMDs), with lamellar structure as that of graphene, has attracted significant attentions in optoelectronics and photonics. Here, we focus on the optical absorption response of a new member TMDs, rhenium disulphide (ReS2) whose monolayer and bulk forms have the nearly identical band structures. The nonlinear saturable and polarization-induced absorption of ReS2 are investigated at near-infrared communication band beyond its bandgap. It is found that the ReS2-covered D-shaped fiber (RDF) displays the remarkable polarization-induced absorption, which indicates the different responses for transverse electric (TE) and transverse magnetic (TM) polarizations relative to ReS2 plane. Nonlinear saturable absorption of RDF exhibits the similar saturable fluence of several tens of μJ/cm2 and modulation depth of about 1% for ultrafast pulses with two orthogonal polarizations. RDF is utilized as a saturable absorber to achieve self-started mode-locking operation in an Er-doped fiber laser. The results broaden the operation wavelength of ReS2 from visible light to around 1550 nm, and numerous applications may benefit from the anisotropic and nonlinear absorption characteristics of ReS2, such as in-line optical polarizers, high-power pulsed lasers, and optical communication system. PMID:28053313

Maximizing power output from continuous-wave single-frequency fiber amplifiers.

PubMed

Ward, Benjamin G

2015-02-15

This Letter reports on a method of maximizing the power output from highly saturated cladding-pumped continuous-wave single-frequency fiber amplifiers simultaneously, taking into account the stimulated Brillouin scattering and transverse modal instability thresholds. This results in a design figure of merit depending on the fundamental mode overlap with the doping profile, the peak Brillouin gain coefficient, and the peak mode coupling gain coefficient. This figure of merit is then numerically analyzed for three candidate fiber designs including standard, segmented acoustically tailored, and micro-segmented acoustically tailored photonic-crystal fibers. It is found that each of the latter two fibers should enable a 50% higher output power than standard photonic crystal fiber.

21 CFR 101.81 - Health claims: Soluble fiber from certain foods and risk of coronary heart disease (CHD).

Code of Federal Regulations, 2011 CFR

2011-04-01

...) of LDL-cholesterol. The scientific evidence establishes that diets high in saturated fat and..., and then removal by centrifugation of the insoluble components consisting of a high portion of protein... of coronary heart disease (CHD). (a) Relationship between diets that are low in saturated fat and...

21 CFR 101.81 - Health claims: Soluble fiber from certain foods and risk of coronary heart disease (CHD).

Code of Federal Regulations, 2014 CFR

2014-04-01

...) of LDL-cholesterol. The scientific evidence establishes that diets high in saturated fat and..., and then removal by centrifugation of the insoluble components consisting of a high portion of protein... of coronary heart disease (CHD). (a) Relationship between diets that are low in saturated fat and...

21 CFR 101.81 - Health claims: Soluble fiber from certain foods and risk of coronary heart disease (CHD).

Code of Federal Regulations, 2013 CFR

2013-04-01

...) of LDL-cholesterol. The scientific evidence establishes that diets high in saturated fat and..., and then removal by centrifugation of the insoluble components consisting of a high portion of protein... of coronary heart disease (CHD). (a) Relationship between diets that are low in saturated fat and...

21 CFR 101.81 - Health claims: Soluble fiber from certain foods and risk of coronary heart disease (CHD).

Code of Federal Regulations, 2012 CFR

2012-04-01

...) of LDL-cholesterol. The scientific evidence establishes that diets high in saturated fat and..., and then removal by centrifugation of the insoluble components consisting of a high portion of protein... of coronary heart disease (CHD). (a) Relationship between diets that are low in saturated fat and...

Psyllium husk fiber supplementation to the diets rich in soybean or coconut oil: hypocholesterolemic effect in healthy humans.

PubMed

Ganji, V; Kies, C V

1996-03-01

The objective of this study was to investigate the effect of psyllium husk fiber supplementation to the diets of soybean and coconut oil on serum lipids in normolipidemic humans. A 28-day study was divided into four 7-day experimental periods. Dietary periods were soybean oil (SO), soybean oil plus psyllium fiber (SO + PF), coconut oil (CO) and coconut oil plus psyllium fiber (CO + PF), and were arranged to a randomized cross over design. Ten subjects consumed controlled diet containing 30% fat calories (20% from test oils and 10% from controlled diet) and 20 g per day of psyllium during fiber supplementation periods. SO + PF diet significantly reduced serum cholesterol compared with SO diet (P < 0.001). CO + PF diet significantly reduced serum cholesterol compared with CO diet (P < 0.014). Hypocholesterolemic response was greater with SO + PF compared with CO + PF (0.36 mmol 1(-1) vs 0.31 mmol 1(-1)). Reductions in low-density lipoprotein (LDL) cholesterol and apolipoprotein (apo) B were parallel to reductions of serum cholesterol. SO diet decreased, while CO diet increased serum cholesterol, LDL cholesterol and apo B. Very-low density lipoprotein cholesterol, high-density lipoprotein cholesterol and apo A-1 were unaffected by psyllium fiber and saturation of fat. Reduction of serum cholesterol was due to reduction of LDL cholesterol. Psyllium fiber supplementation lowered serum cholesterol regardless of saturation level of dietary fat.

All fiber passively Q-switched laser

DOEpatents

Soh, Daniel B. S.; Bisson, Scott E

2015-05-12

Embodiments relate to an all fiber passively Q-switched laser. The laser includes a large core doped gain fiber having a first end. The large core doped gain fiber has a first core diameter. The laser includes a doped single mode fiber (saturable absorber) having a second core diameter that is smaller than the first core diameter. The laser includes a mode transformer positioned between a second end of the large core doped gain fiber and a first end of the single mode fiber. The mode transformer has a core diameter that transitions from the first core diameter to the second core diameter and filters out light modes not supported by the doped single mode fiber. The laser includes a laser cavity formed between a first reflector positioned adjacent the large core doped gain fiber and a second reflector positioned adjacent the doped single mode fiber.

CsPbBr{sub 3} nanocrystal saturable absorber for mode-locking ytterbium fiber laser

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

Zhou, Yan; Li, Yue; Xu, Jianqiu

Cesium lead halide perovskite nanocrystals (CsPbX{sub 3}, X = Cl, Br, I) have been reported as efficient light-harvesting and light-emitting semiconductor materials, but their nonlinear optical properties have been seldom touched upon. In this paper, we prepare layered CsPbBr{sub 3} nanocrystal films and characterize their physical properties. Broadband linear absorption from ∼0.8 to over 2.2 μm and nonlinear optical absorption at the 1-μm wavelength region are measured. The CsPbBr{sub 3} saturable absorber (SA), manufactured by drop-casting of colloidal CsPbBr{sub 3} liquid solution on a gold mirror, shows modulation depth and saturation intensity of 13.1% and 10.7 MW/cm{sup 2}, respectively. With this SA, mode-locking operationmore » of a polarization-maintained ytterbium fiber laser produces single pulses with duration of ∼216 ps, maximum average output power of 10.5 mW, and the laser spectrum is centered at ∼1076 nm. This work shows that CsPbBr{sub 3} films can be efficient SA candidates for fiber lasers and also have great potential to become broadband linear and nonlinear optical materials for photonics and optoelectronics.« less

Passively synchronized Q-switched and mode-locked dual-band Tm3+:ZBLAN fiber lasers using a common graphene saturable absorber

NASA Astrophysics Data System (ADS)

Jia, Chenglai; Shastri, Bhavin J.; Abdukerim, Nurmemet; Rochette, Martin; Prucnal, Paul R.; Saad, Mohammed; Chen, Lawrence R.

2016-11-01

Dual-band fiber lasers are emerging as a promising technology to penetrate new industrial and medical applications from their dual-band properties, in addition to providing compactness and environmental robustness from the waveguide structure. Here, we demonstrate the use of a common graphene saturable absorber and a single gain medium (Tm3+:ZBLAN fiber) to implement (1) a dual-band fiber ring laser with synchronized Q-switched pulses at wavelengths of 1480 nm and 1840 nm, and (2) a dual-band fiber linear laser with synchronized mode-locked pulses at wavelengths of 1480 nm and 1845 nm. Q-switched operation at 1480 nm and 1840 nm is achieved with a synchronized repetition rate from 20 kHz to 40.5 kHz. For synchronous mode-locked operation, pulses with full-width at half maximum durations of 610 fs and 1.68 ps at wavelengths of 1480 nm and 1845 nm, respectively, are obtained at a repetition rate of 12.3 MHz. These dual-band pulsed sources with an ultra-broadband wavelength separation of ~360 nm will add new capabilities in applications including optical sensing, spectroscopy, and communications.

Passively synchronized Q-switched and mode-locked dual-band Tm3+:ZBLAN fiber lasers using a common graphene saturable absorber.

PubMed

Jia, Chenglai; Shastri, Bhavin J; Abdukerim, Nurmemet; Rochette, Martin; Prucnal, Paul R; Saad, Mohammed; Chen, Lawrence R

2016-11-02

Dual-band fiber lasers are emerging as a promising technology to penetrate new industrial and medical applications from their dual-band properties, in addition to providing compactness and environmental robustness from the waveguide structure. Here, we demonstrate the use of a common graphene saturable absorber and a single gain medium (Tm 3+ :ZBLAN fiber) to implement (1) a dual-band fiber ring laser with synchronized Q-switched pulses at wavelengths of 1480 nm and 1840 nm, and (2) a dual-band fiber linear laser with synchronized mode-locked pulses at wavelengths of 1480 nm and 1845 nm. Q-switched operation at 1480 nm and 1840 nm is achieved with a synchronized repetition rate from 20 kHz to 40.5 kHz. For synchronous mode-locked operation, pulses with full-width at half maximum durations of 610 fs and 1.68 ps at wavelengths of 1480 nm and 1845 nm, respectively, are obtained at a repetition rate of 12.3 MHz. These dual-band pulsed sources with an ultra-broadband wavelength separation of ~360 nm will add new capabilities in applications including optical sensing, spectroscopy, and communications.

Vector solitons in harmonic mode-locked erbium-doped fiber lasers

NASA Astrophysics Data System (ADS)

Habruseva, Tatiana; Mkhitaryan, Mkhitar; Mou, Chengbo; Rozhin, Aleksey; Turitsyn, Sergei K.; Sergeyev, Sergey V.

2014-05-01

We report experimental study of vector solitons for the fundamental and harmonic mode-locked operation in erbiumdoper fiber lasers with carbon nanotubes based saturable absorbers and anomalous dispersion cavities. We measure evolution of the output pulses polarization and demonstrate vector solitons with various polarization attractors, including locked polarization, periodic polarization switching, and polarization precession.

Cellulosic fraction of rice bran fibre alters the conformation and inhibits the activity of porcine pancreatic lipase

USDA-ARS?s Scientific Manuscript database

The anti-lipase properties of insoluble dietary fiber obtained from rice bran treated with H2SO4 followed by 1.25% KOH were investigated and compared. Porcine pancreatic lipase (PL) adsorbed with higher velocity and saturated at a higher level on the rice bran fibers prepared with higher concentrat...

L-band ultrafast fiber laser mode locked by carbon nanotubes

NASA Astrophysics Data System (ADS)

Sun, Z.; Rozhin, A. G.; Wang, F.; Scardaci, V.; Milne, W. I.; White, I. H.; Hennrich, F.; Ferrari, A. C.

2008-08-01

We fabricate a nanotube-polyvinyl alcohol saturable absorber with a broad absorption at 1.6 μm. We demonstrate a pulsed fiber laser working in the telecommunication L band by using this composite as a mode locker. This gives ˜498±16 fs pulses at 1601 nm with a 26.7 MHz repetition rate.

Multilayered thermal insulation formed of zirconia bonded layers of zirconia fibers and metal oxide fibers and method for making same

DOEpatents

Wrenn, Jr., George E.; Holcombe, Jr., Cressie E.

1988-01-01

A multilayered thermal insulating composite is formed of a first layer of zirconia-bonded zirconia fibers for utilization near the hot phase or surface of a furnace or the like. A second layer of zirconia-bonded metal oxide fibers is attached to the zirconia fiber layer by a transition layer formed of intermingled zirconia fibers and metal oxide fibers. The thermal insulation is fabricated by vacuum molding with the layers being sequentially applied from aqueous solutions containing the fibers to a configured mandrel. A portion of the solution containing the fibers forming the first layer is intermixed with the solution containing the fibers of the second layer for forming the layer of mixed fibers. The two layers of fibers joined together by the transition layer are saturated with a solution of zirconium oxynitrate which provides a zirconia matrix for the composite when the fibers are sintered together at their nexi.

Multilayered thermal insulation formed of zirconia bonded layers of zirconia fibers and metal oxide fibers and method for making same

DOEpatents

Wrenn, G.E. Jr.; Holcombe, C.E. Jr.

1988-09-13

A multilayered thermal insulating composite is formed of a first layer of zirconia-bonded zirconia fibers for utilization near the hot phase or surface of a furnace or the like. A second layer of zirconia-bonded metal oxide fibers is attached to the zirconia fiber layer by a transition layer formed of intermingled zirconia fibers and metal oxide fibers. The thermal insulation is fabricated by vacuum molding with the layers being sequentially applied from aqueous solutions containing the fibers to a configured mandrel. A portion of the solution containing the fibers forming the first layer is intermixed with the solution containing the fibers of the second layer for forming the layer of mixed fibers. The two layers of fibers joined together by the transition layer are saturated with a solution of zirconium oxynitrate which provides a zirconia matrix for the composite when the fibers are sintered together at their nexi.

The effects of adding fat to diets of lactating dairy cows on total-tract neutral detergent fiber digestibility: A meta-analysis.

PubMed

Weld, K A; Armentano, L E

2017-03-01

The objective of this meta-analysis was to determine the effects of supplemental fat on fiber digestibility in lactating dairy cattle. Published papers that evaluated the effects of adding fat to the diets of lactating dairy cattle on total-tract neutral detergent fiber digestibility (ttNDFd) and dry matter intake (DMI) were compiled. The final data set included 108 fat-supplemented treatment means, not including low-fat controls, from 38 publications. The fat-supplemented treatment means exhibited a wide range of ttNDFd (49.4% ± 9.3, mean ± standard deviation) and DMI (21.3 kg/d ± 3.5). Observations were summarized as the difference between the treatment means for fat-supplemented diets minus their respective low-fat control means. Additionally, those differences were divided by the difference in diet fatty acid (FA) concentration between the treatment and control diets. Treatment means were categorized by the type of fat supplement. Supplementing 3% FA in the diet as medium-chain fats (containing predominately 12- and 14-carbon saturated FA) or unsaturated vegetable oil decreased ttNDFd by 8.0 and 1.2 percentage units, respectively. Adding 3% calcium salts of long-chain FA or saturated fats increased ttNDFd by 3.2 and 1.3 percentage units, respectively. No other fat supplement type affected ttNDFd. Except for saturated fats and animal-vegetable fats, supplementing dietary fat decreased DMI. When the values for changes in ttNDFd are regressed on changes in DMI there was a positive relationship, though the coefficient of determination is only 0.20. When changes in ttNDFd were regressed on changes in DMI, within individual fat supplement types, there was no relationship within calcium salt supplements. There was a positive relationship between changes in ttNDFd and changes in DMI for saturated fats. Neither relationship suggested that the increased ttNDFd with calcium salts or saturated FA was due to decreased DMI for these fat sources. A subset of the means included measured ruminal neutral detergent fiber digestion. Analysis of this smaller data set did not suggest that ruminal neutral detergent fiber digestibility is depressed by fat supplementation more than ttNDFd. Adding fats, other than those with medium-chain FA, consistently increased digestible energy density of the diet. However, due to reduced DMI, this increased energy density may not result in increased digestible nutrient intake. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Improvements in decay resistance based on moisture exclusion

Treesearch

Roger M. Rowell; Rebecca E. Ibach

2000-01-01

Moisture content has an effect on the biological decay of wood. The literature states that serious decay occurs when the moisture content of wood is above the fiber saturation point (FSP), which is the measurement of the moisture content of wood when the cell walls are saturated and the cell cavities free from water (average 30%). We can chemically modify wood...

Low threshold L-band mode-locked ultrafast fiber laser assisted by microfiber-based carbon nanotube saturable absorber

NASA Astrophysics Data System (ADS)

Lau, K. Y.; Ng, E. K.; Abu Bakar, M. H.; Abas, A. F.; Alresheedi, M. T.; Yusoff, Z.; Mahdi, M. A.

2018-04-01

We demonstrate a passively mode-locked erbium-doped fiber laser in L-band wavelength region with low mode-locking threshold employing a 1425 nm pump wavelength. The mode-locking regime is generated by microfiber-based saturable absorber using carbon nanotube-polymer composite in a ring cavity. This carbon nanotube saturable absorber shows saturation intensity of 9 MW/cm2. In this work, mode-locking laser threshold is observed at 36.4 mW pump power. At the maximum pump power of 107.6 mW, we obtain pulse duration at full-width half-maximum point of 490 fs and time bandwidth product of 0.33, which corresponds to 3-dB spectral bandwidth of 5.8 nm. The pulse repetition rate remains constant throughout the experiment at 5.8 MHz due to fixed cavity length of 35.5 m. Average output power and pulse energy of 10.8 mW and 1.92 nJ are attained respectively through a 30% laser output extracted from the mode-locked cavity. This work highlights the feasibility of attaining a low threshold mode-locked laser source to be employed as seed laser in L-band wavelength region.

Radially polarized and passively Q-switched fiber laser

PubMed Central

Lin, Di; Xia, Kegui; Li, Ruxin; Li, Xiaojun; Li, Guoqiang; Ueda, Ken-ichi; Li, Jianlang

2017-01-01

We report, for the first time to our knowledge, a radially polarized and passively Q-switched Yb-doped fiber laser. By using a Cr4+:YAG crystal as a saturable absorber and a photonic crystal grating as a polarization mirror, a radially polarized pulse is produced, which has 202 W of peak power, 75 ns duration, and ~92% polarization purity at a 56.6 kHz repetition rate. The Q-switched pulse with radial polarization from the fiber laser would facilitate numerous applications. PMID:21042354

Fiber Strength of Hi Nicalon(TM) S After Oxidation and Scale Crystallization in Si(OH)4 Saturated Steam (Postprint)

DTIC Science & Technology

2017-02-06

conducted for the longest times because the fibers would completely oxidize. The SiO2 tube would warp during experiments run at temperatures over 1200° C ...Chollon, G.; Labrugere, C .; Lahaye, M.; Guette, A.; Bruneel, J . L.; Couzi, M.; Naslain, R.; Jiang, D. L., Characterization of Nearly Stoichiometric...Electron Beam Irradiation Curing - A Review. J . Ceram. Soc. Japan 2006, 114, 455-460. 8. Sauder, C .; Lamon, J ., Tensile Creep Behavior of SiC-Based Fibers

Dietary Fibers and Cardiometabolic Diseases

PubMed Central

Riccioni, Graziano; Sblendorio, Valeriana; Gemello, Eugenio; Di Bello, Barbara; Scotti, Luca; Cusenza, Salvatore; D’Orazio, Nicolantonio

2012-01-01

The high prevalence of cardiovascular disease (CVD) is largely attributable to the contemporary lifestyle that is often sedentary and includes a diet high in saturated fats and sugars and low ingestion of polyunsaturated fatty acids (PUFAs), fruit, vegetables, and fiber. Experimental data from both animals and humans suggest an association between increased dietary fiber (DF) intakes and improved plasma lipid profiles, including reduced low density lipoprotein cholesterol (LDL-C) concentrations. These observations underline that the intake of DF may protect against heart disease and stroke. PMID:22408406

Dark solitons in erbium-doped fiber lasers based on indium tin oxide as saturable absorbers

NASA Astrophysics Data System (ADS)

Guo, Jia; Zhang, Huanian; Li, Zhen; Sheng, Yingqiang; Guo, Quanxin; Han, Xile; Liu, Yanjun; Man, Baoyuan; Ning, Tingyin; Jiang, Shouzhen

2018-04-01

Dark solitons, which have good stability, long transmission distance and strong anti-interference ability. By using a coprecipitation method, the high quality indium tin oxide (ITO) were prepared with an average diameter of 34.1 nm. We used a typical Z-scan scheme involving a balanced twin-detector measurement system to investigated nonlinear optical properties of the ITO nanoparticles. The saturation intensity and modulation depths are 13.21 MW/cm2 and 0.48%, respectively. In an erbium-doped fiber (EDF) lasers, we using the ITO nanoparticles as saturable absorber (SA), and the formation of dark soliton is experimentally demonstrated. The generated dark solitons are centered at the wavelength of 1561.1 nm with a repetition rate of 22.06 MHz. Besides, the pulse width and pulse-to-pulse interval of the dark solitons is ∼1.33ns and 45.11 ns, respectively. These results indicate that the ITO nanoparticles is a promising nanomaterial for ultrafast photonics.

Oximeter for reliable clinical determination of blood oxygen saturation in a fetus

DOEpatents

Robinson, Mark R.; Haaland, David M.; Ward, Kenneth J.

1996-01-01

With the crude instrumentation now in use to continuously monitor the status of the fetus at delivery, the obstetrician and labor room staff not only over-recognize the possibility of fetal distress with the resultant rise in operative deliveries, but at times do not identify fetal distress which may result in preventable fetal neurological harm. The invention, which addresses these two basic problems, comprises a method and apparatus for non-invasive determination of blood oxygen saturation in the fetus. The apparatus includes a multiple frequency light source which is coupled to an optical fiber. The output of the fiber is used to illuminate blood containing tissue of the fetus. In the preferred embodiment, the reflected light is transmitted back to the apparatus where the light intensities are simultaneously detected at multiple frequencies. The resulting spectrum is then analyzed for determination of oxygen saturation. The analysis method uses multivariate calibration techniques that compensate for nonlinear spectral response, model interfering spectral responses and detect outlier data with high sensitivity.

High-temperature-resistant distributed Bragg reflector fiber laser written in Er/Yb co-doped fiber.

PubMed

Guan, Bai-Ou; Zhang, Yang; Wang, Hong-Jun; Chen, Da; Tam, Hwa-Yaw

2008-03-03

We present a high-temperature-resistant distributed Bragg reflector fiber laser photowritten in Er/Yb codoped phosphosilicate fiber that is capable of long-term operation at 500 degrees C. Highly saturated Bragg gratings are directly inscribed into the Er/Yb fiber without hydrogen loading by using a 193 nm excimer laser and phase mask method. After annealing at elevated temperature, the remained gratings are strong enough for laser oscillation. The laser operates in robust single mode with output power more than 1 dBm and signal-to-noise ratio better than 70 dB over the entire temperature range from room temperature to 500 degrees C.

256 fs, 2 nJ soliton pulse generation from MoS2 mode-locked fiber laser

NASA Astrophysics Data System (ADS)

Jiang, Zike; Chen, Hao; Li, Jiarong; Yin, Jinde; Wang, Jinzhang; Yan, Peiguang

2017-12-01

We demonstrate an Er-doped fiber laser (EDFL) mode-locked by a MoS2 saturable absorber (SA), delivering a 256 fs, 2 nJ soliton pulse at 1563.4 nm. The nonlinear property of the SA prepared by magnetron sputtering deposition (MSD) is measured with a modulation depth (MD) of ∼19.48% and a saturable intensity of 4.14 MW/cm2. To the best of our knowledge, the generated soliton pulse has the highest pulse energy of 2 nJ among the reported mode-locked EDFLs based on transition metal dichalcogenides (TMDs). Our results indicate that MSD-grown SAs could offer an exciting platform for high pulse energy and ultrashort pulse generation.

Extreme Magneto-transport of Bulk Carbon Nanotubes in Sorted Electronic Concentrations and Aligned High Performance Fiber

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

Bulmer, John S.; Lekawa-Raus, Agnieszka; Rickel, Dwight G.

We explored high-field (60 T) magneto-resistance (MR) with two carbon nanotube (CNT) material classes: (1) unaligned single-wall CNTs (SWCNT) films with controlled metallic SWCNT concentrations and doping degree and (2) CNT fiber with aligned, long-length microstructure. All unaligned SWCNT films showed localized hopping transport where high-field MR saturation definitively supports spin polarization instead of a more prevalent wave function shrinking mechanism. Nitric acid exposure induced an insulator to metal transition and reduced the positive MR component. Aligned CNT fiber, already on the metal side of the insulator to metal transition, had positive MR without saturation and was assigned to classicalmore » MR involving electronic mobility. Subtracting high-field fits from the aligned fiber’s MR yielded an unconfounded negative MR, which was assigned to weak localization. It is concluded that fluctuation induced tunnelling, an extrinsic transport model accounting for most of the aligned fiber’s room temperature resistance, appears to lack MR field dependence.« less

Mid-infrared Fe2+:ZnSe semiconductor saturable absorber mirror for passively Q-switched Er3+-doped ZBLAN fiber laser

NASA Astrophysics Data System (ADS)

Ning, Shougui; Feng, Guoying; Dai, Shenyu; Zhang, Hong; Zhang, Wei; Deng, Lijuan; Zhou, Shouhuan

2018-02-01

A mid-infrared (mid-IR) semiconductor saturable absorber mirror (SESAM) based on Fe2+:ZnSe for passively Q-switched Er3+-doped ZBLAN fiber laser has been demonstrated. Fe2+:ZnSe SESAM was fabricated by electron beam evaporation method. Fe2+ was innovatively doped into the reflective Bragg stack, in which ZnSe layer served as both doped matrix and high refractive layer during the fabricating process. By using the Fe2+:ZnSe SESAM, stable passively Q-switched pulses with the minimum pulse width of 0.43 μs under a repetition rate of 160.82 kHz were obtained. The recorded maximum average output power of 873 mW with a peak power of 12.59 W and pulse energy of 5.43 μJ were achieved. The results demonstrated a new method for fabricating Fe2+:ZnSe SESAM, which can be used in compact mid-IR Q-switched fiber laser.

A Filmy Black-Phosphorus Polyimide Saturable Absorber for Q-Switched Operation in an Erbium-Doped Fiber Laser.

PubMed

Feng, Tianxian; Mao, Dong; Cui, Xiaoqi; Li, Mingkun; Song, Kun; Jiang, Biqiang; Lu, Hua; Quan, Wangmin

2016-11-11

We demonstrate an erbium-doped fiber laser passively Q-switched by a black-phosphorus polyimide film. The multi-layer black-phosphorus (BP) nanosheets were prepared via a liquid exfoliation approach exploiting N -methylpyrrolidone as the dispersion liquid. By mixing the BP nanosheets with polyimide (PI), a piece of BP-PI film was obtained after evaporating the mixture in a petri dish. The BP-PI saturable absorber had a modulation depth of 0.47% and was inserted into an erbium-doped fiber laser to realize passive Q-switched operations. The repetition rate of the Q-switched laser increased from 5.73 kHz to 31.07 kHz when the laser pump was enhanced from 31.78 mW to 231.46 mW. Our results show that PI is an excellent host material to protect BP from oxidation, and the BP-PI film can act as a promising nonlinear optical device for laser applications.

Extreme Magneto-transport of Bulk Carbon Nanotubes in Sorted Electronic Concentrations and Aligned High Performance Fiber

DOE PAGES

Bulmer, John S.; Lekawa-Raus, Agnieszka; Rickel, Dwight G.; ...

2017-09-22

We explored high-field (60 T) magneto-resistance (MR) with two carbon nanotube (CNT) material classes: (1) unaligned single-wall CNTs (SWCNT) films with controlled metallic SWCNT concentrations and doping degree and (2) CNT fiber with aligned, long-length microstructure. All unaligned SWCNT films showed localized hopping transport where high-field MR saturation definitively supports spin polarization instead of a more prevalent wave function shrinking mechanism. Nitric acid exposure induced an insulator to metal transition and reduced the positive MR component. Aligned CNT fiber, already on the metal side of the insulator to metal transition, had positive MR without saturation and was assigned to classicalmore » MR involving electronic mobility. Subtracting high-field fits from the aligned fiber’s MR yielded an unconfounded negative MR, which was assigned to weak localization. It is concluded that fluctuation induced tunnelling, an extrinsic transport model accounting for most of the aligned fiber’s room temperature resistance, appears to lack MR field dependence.« less

Black phosphorus as a saturable absorber for generating mode-locked fiber laser in normal dispersion regime

NASA Astrophysics Data System (ADS)

Latiff, A. A.; Rusdi, M. F. M.; Hisyam, M. B.; Ahmad, H.; Harun, S. W.

2016-11-01

This paper reports a few-layer black phosphorus (BP) as a saturable absorber (SA) or phase-locker in generating modelocked pulses from a double-clad ytterbium-doped fiber laser (YDFL). We mechanically exfoliated the BP flakes from BP crystal through a scotch tape, and repeatedly press until the flakes thin and spread homogenously. Then, a piece of BP tape was inserted in the cavity between two fiber connectors end facet. Under 810 mW to 1320 mW pump power, stable mode-locked operation at 1085 nm with a repetition rate of 13.4 MHz is successfully achieved in normal dispersion regime. Before mode-locked operation disappears above maximum pump, the output power and pulse energy is about 80 mW and 6 nJ, respectively. This mode-locked laser produces peak power of 0.74 kW. Our work may validates BP SA as a phase-locker related to two-dimensional nanomaterials and pulsed generation in normal dispersion regime.

Effects of water states on steam explosion of lignocellulosic biomass.

PubMed

Sui, Wenjie; Chen, Hongzhang

2016-01-01

The work aimed to identify the complexity and roles of water states in steam explosion process of corn stalk to enhance the treatment efficiency. Results showed that two main water states with different mobility existed in corn stalk and influenced steam explosion treatment. By correlating dynamic water states data to feedstock mechanical properties and treatment process characteristics, the bound water being the excellent plasticizer that reduced the mechanical strength of fibers by over 30%, was conducive to treatment; while, the free water presenting buffering effects in treatment by hindering heat transfer which was reflected by the increase of temperature rising time by 1.29 folds and steam consumption by 2.18 folds, was not conducive. The distinguished point of these two waters was fiber saturated point. By considering treatment efficacy and energy consumption, the significance of fiber saturated point was highlighted as the optimal water states for steam explosion of corn stalk. Copyright © 2015 Elsevier Ltd. All rights reserved.

Erbium-doped fiber laser passively mode locked with few-layer WSe2/MoSe2 nanosheets

NASA Astrophysics Data System (ADS)

Mao, Dong; She, Xiaoyang; Du, Bobo; Yang, Dexing; Zhang, Wending; Song, Kun; Cui, Xiaoqi; Jiang, Biqiang; Peng, Tao; Zhao, Jianlin

2016-03-01

Few-layer transition-metal dichalcogenide WSe2/MoSe2 nanosheets are fabricated by a liquid exfoliation technique using sodium deoxycholate bile salt as surfactant, and their nonlinear optical properties are investigated based on a balanced twin-detector measurement scheme. It is demonstrated that both types of nanosheets exhibit nonlinear saturable absorption properties at the wavelength of 1.55 μm. By depositing the nanosheets on side polished fiber (SPF) or mixing the nanosheets with polyvinyl alcohol (PVA) solution, SPF-WSe2 saturable absorber (SA), SPF-MoSe2 SA, PVA-WSe2 SA, and PVA-MoSe2 SA are successfully fabricated and further tested in erbium-doped fiber lasers. The SPF-based SA is capable of operating at the high pump regime without damage, and a train of 3252.65 MHz harmonically mode-locked pulses are obtained based on the SPF-WSe2 SA. Soliton mode locking operations are also achieved in the fiber laser separately with other three types of SAs, confirming that the WSe2 and MoSe2 nanosheets could act as cost-effective high-power SAs for ultrafast optics.

Q-switched all-fiber laser with short pulse duration based on tungsten diselenide

NASA Astrophysics Data System (ADS)

Li, Wenyi; OuYang, Yuyi; Ma, Guoli; Liu, Mengli; Liu, Wenjun

2018-05-01

Fiber lasers are widely used in industrial processing, sensing, medical and communications applications due to their simple structure, good stability and low cost. With the rapid development of fiber lasers and the sustained improvement of industrial laser quality requirements, researchers in ultrafast optics focus on how to get laser pulses with high output power and narrow pulse duration. Q-switched technology is one of the most effective techniques to generate ultrashort pulses. In this paper, a tungsten diselenide saturable absorber with 16.82% modulation depth is prepared by chemical vapor deposition. Experimental results show that when the pump power changes from 115.7 mW to 630 mW, the all-fiber laser can achieve a stable Q-switched pulse output. The repetition rate of the output pulse varies from 80.32 kHz to 204.2 kHz, the pulse duration is 581 ns, the maximum output power is 17.1 mW and the maximum pulse energy is 83.7 nJ. Results in this paper show that tungsten diselenide can be applied to ultrafast optics, which is a kind of saturable absorption material with excellent properties.

A fiberoptic reflection oximeter.

PubMed

Landsman, M L; Knop, N; Kwant, G; Mook, G A; Zijlstra, W G

1978-03-20

A catheter tip oximeter is described consisting of a cardiac catheter containing optical fibers, and incandescent light source, a light detection unit and a processing unit. Half of the optical fibers guide the light to the blood at the tip of the catheter, the other half the backscattered (reflected) light to the detection unit. The detection unit contains a dichroic mirror, transmitting most of the light with lambda less than 800 nm and reflecting most of the light with lambda greater than 900 nm, thus splitting the light into two beams. These pass through interference filters with nominal wavelengths of 640 and 920 nm respectively, and are focused on silicium barrier layer photocells. The photocell signals are amplified and fed into a divider giving the ratio of measuring (R640) and compensating (R920) photocell output. The relationship between log R640/R920 and oxygen saturation is represented by a slightly curved line. The relation may be linearized by subtracting a constant voltage from the divided output before taking the logarithm. The slope of the calibration line is dependent on the total haemoglobin concentration. Nonetheless an average calibration line can be used between 70 and 100% oxygen saturation. For 78 measurements of pig blood samples in this range (haemoglobin concentration between 96 and 161 g.1(-1)), the standard deviation of the difference between the fiberoptic oximeter and a Radiometer OSM1 oxygen saturation meter was 1.9% saturation, for 152 samples over the entire saturation range the standard deviation of the difference was 3.1% saturation. The influence of the flow velocity of blood on the light reflection depends on wavelength as well as on oxygen saturation. Therefore, complete compensation for the flow effect is not possible by simple means.

High-gain EDFA using ASE suppression: numerical simulation and experimental characterization

NASA Astrophysics Data System (ADS)

Woellner, Eudes F.; Fugihara, Meire C.; Vendramin, Marcio; Chitz, Edson; Kalinowski, Hypolito J.; Pontes, Maria J.

2001-08-01

A single stage, bi-directionally pumped Erbium Doped Fiber Amplifier is studied, using a scheme that reduces the counter propagating ASE, avoiding self saturation due to ASE. The amplifier is numerically simulated and experimentally characterized. Gain, saturation and polarization dependence measurements are carried to compare with simulated results. Transient response is simulated to verify the amplifier performance in cable television distribution network.

Passively mode-locked fiber laser based on a hollow-core photonic crystal fiber filled with few-layered graphene oxide solution.

PubMed

Liu, Zhi-Bo; He, Xiaoying; Wang, D N

2011-08-15

We demonstrate a nanosecond-pulse erbium-doped fiber laser that is passively mode locked by a hollow-core photonic crystal fiber filled with few-layered graphene oxide solution. Owing to the good solution processing capability of few-layered graphene oxide, which can be filled into the core of a hollow-core photonic crystal fiber through a selective hole filling process, a graphene saturable absorber can be successfully fabricated. The output pulses obtained have a center wavelength, pulse width, and repetition rate of 1561.2 nm, 4.85 ns, and 7.68 MHz, respectively. This method provides a simple and efficient approach to integrate the graphene into the optical fiber system. © 2011 Optical Society of America

Sub-femtosecond timing jitter, all-fiber, CNT-mode-locked Er-laser at telecom wavelength.

PubMed

Kim, Chur; Bae, Sangho; Kieu, Khanh; Kim, Jungwon

2013-11-04

We demonstrate a 490-attosecond timing jitter (integration bandwidth: 10 kHz - 39.4 MHz) optical pulse train from a 78.7-MHz repetition rate, all-fiber soliton Er laser mode-locked by a fiber tapered carbon nanotube saturable absorber (ft-CNT-SA). To achieve this jitter performance, we searched for a net cavity dispersion condition where the Gordon-Haus jitter is minimized while maintaining stable soliton mode-locking. Our result shows that optical pulse trains with well below a femtosecond timing jitter can be generated from a self-starting and robust all-fiber laser operating at telecom wavelength.

Measurement of distributed strain and temperature based on higher order and higher mode Bragg conditions

NASA Technical Reports Server (NTRS)

Sirkis, James S. (Inventor); Sivanesan, Ponniah (Inventor); Venkat, Venki S. (Inventor)

2001-01-01

A Bragg grating sensor for measuring distributed strain and temperature at the same time comprises an optical fiber having a single mode operating wavelength region and below a cutoff wavelength of the fiber having a multimode operating wavelength region. A saturated, higher order Bragg grating having first and second order Bragg conditions is fabricated in the optical fiber. The first order of Bragg resonance wavelength of the Bragg grating is within the single mode operating wavelength region of the optical fiber and the second order of Bragg resonance wavelength is below the cutoff wavelength of the fiber within the multimode operating wavelength region. The reflectivities of the saturated Bragg grating at the first and second order Bragg conditions are less than two orders of magnitude of one another. In use, the first and second order Bragg conditions are simultaneously created in the sensor at the respective wavelengths and a signal from the sensor is demodulated with respect to each of the wavelengths corresponding to the first and second order Bragg conditions. Two Bragg conditions have different responsivities to strain and temperature, thus allowing two equations for axial strain and temperature to be found in terms of the measure shifts in the primary and second order Bragg wavelengths. This system of equations can be solved for strain and temperature.

Fiber in Diet Is Associated with Improvement of Glycated Hemoglobin and Lipid Profile in Mexican Patients with Type 2 Diabetes.

PubMed

Velázquez-López, Lubia; Muñoz-Torres, Abril Violeta; García-Peña, Carmen; López-Alarcón, Mardia; Islas-Andrade, Sergio; Escobedo-de la Peña, Jorge

2016-01-01

Objective. To assess the association of dietary fiber on current everyday diet and other dietary components with glycated hemoglobin levels (HbA1c), glucose, lipids profile, and body weight body weight, in patients with type 2 diabetes. Methods. A cross-sectional survey of 395 patients with type 2 diabetes was performed. HbA1c, fasting glucose, triglycerides, and lipids profile were measured. Weight, waist circumference, blood pressure, and body composition were measured. Everyday diet with a semiquantitative food frequency questionnaire was evaluated. ANOVA, Kruskal-Wallis, chi-square tests and multivariate logistic regression were used in statistical analysis. Results. Higher fiber intake was associated with a low HbA1c, high HDL-c levels, low weight, and waist circumference. The highest tertile of calories consumption was associated with a higher fasting glucose level and weight. The highest tertile of carbohydrate consumption was associated with a lower weight. The lowest tertile of total fat and saturated fat was associated with the highest tertile of HDL-c levels, and lower saturated fat intake was associated with lower weight (p < 0.05). Conclusions. A higher content of fiber in the diet reduces HbA1c and triglycerides, while improving HDL-c levels. Increasing fiber consumption while lowering calorie consumption seems to be an appropriate strategy to reduce body weight and promote blood glucose control.

Carbon fiber composite molecular sieve electrically regenerable air filter media

DOEpatents

Wilson, Kirk A.; Burchell, Timothy D.; Judkins, Roddie R.

1998-01-01

An electrically regenerable gas filter system includes a carbon fiber composite molecular sieve (CFCMS) filter medium. After a separate medium-efficiency pre-filter removes particulate from the supply airstream, the CFCMS filter sorbs gaseous air pollutants before the air is recirculated to the space. When saturated, the CFCMS media is regenerated utilizing a low-voltage current that is caused to pass through the filter medium.

Compact passively Q-switched single-frequency Er3+/Yb3+ codoped phosphate fiber laser

NASA Astrophysics Data System (ADS)

Zhang, Yuanfei; Wang, Simin; Lin, Wei; Mo, Shupei; Zhao, Qilai; Yang, Changsheng; Feng, Zhouming; Deng, Huaqiu; Peng, Mingying; Yang, Zhongmin; Xu, Shanhui

2017-05-01

We present a compact passively Q-switched single-frequency fiber laser based on a 12-mm-long laboratory-built highly Er3+/Yb3+ codoped phosphate fiber (EYDPF) and a semiconductor saturable absorber mirror (SESAM). An effective cavity length of less than 20 mm ensures the stable single-frequency operation of the Q-switched fiber laser. By employing a SESAM for Q-switching, a single-pulse energy of more than 34.4 nJ is realized with the narrowest pulse duration of 95 ns, and the repetition rate of the Q-switched fiber laser reaches over 600 kHz. In addition, the optical signal-to-noise ratio of the output laser is as high as 68.0 dB.

Mode instability in a Yb-doped stretched core fiber

NASA Astrophysics Data System (ADS)

Xia, N.; Yoo, S.

2017-02-01

In this work we present the theoretical study of transverse mode instability (TMI) in ytterbium (Yb)-doped rectangular core fibers with different core aspect ratios using the fast Fourier transform (FFT) beam propagation method (BPM). As expected, the rectangular core fiber with larger aspect ratio (AR.) offers more efficient heat dissipation than a circular core fiber. However, it is found that the rectangular core fiber does not benefit from the better heat dissipation to suppress the TMI when compared to the circular core counterpart. The temperature building in the rectangular core fiber decreases by up to 24.6% with a 10:1 aspect ratio core, while threshold pump power drops by up to 38.3% when compared with a circular core fiber with the same core area. Our study reveals that a smaller effective refractive index difference between modes and a weaker gain saturation effect compensate the thermal advantage from more efficient heat dissipation.

Passively Q-switched of EDFL employing multi-walled carbon nanotubes with diameter less than 8 nm as saturable absorber

NASA Astrophysics Data System (ADS)

Nur Fatin Zuikafly, Siti; Ahmad, Fauzan; Haniff Ibrahim, Mohd; Wadi Harun, Sulaiman

2017-11-01

The paper demonstrates passively Q-switched erbium-doped fiber laser implementing multiwalled carbon nanotubes (MWCNTs) based saturable absorber. The paper is the first to report the use of the MWCNTs with diameter less than 8 nm as typically, the diameter used is 10 to 20 nm. The MWCNTs is incorporated with water soluble host polymer, polyvinyl alcohol (PVA) to produce a MWCNTs polymer composite thin film which is then sandwiched between two fiber connectors. The fabricated SA is employed in the laser experimental setup in ring cavity. The Q-switching regime started at threshold pump power of 103 mW and increasable to 215 mW. The stable pulse train from 41.6 kHz to 76.92 kHz with maximum average output power and pulse energy of 0.17 mW and 3.39 nJ are produced. The shortest pulse width of 1.9 μs is obtained in the proposed experimental work, making it the lowest pulse width ever reported using MWCNTs-based saturable absorber.

Stiffness and fraction of Myosin motors responsible for active force in permeabilized muscle fibers from rabbit psoas.

PubMed

Linari, Marco; Caremani, Marco; Piperio, Claudia; Brandt, Philip; Lombardi, Vincenzo

2007-04-01

The stiffness of the single myosin motor (epsilon) is determined in skinned fibers from rabbit psoas muscle by both mechanical and thermodynamic approaches. Changes in the elastic strain of the half-sarcomere (hs) are measured by fast mechanics both in rigor, when all myosin heads are attached, and during active contraction, with the isometric force (T0) modulated by changing either [Ca2+] or temperature. The hs compliance is 43.0+/-0.8 nm MPa-1 in isometric contraction at saturating [Ca2+], whereas in rigor it is 28.2+/-1.1 nm MPa-1. The equivalent compliance of myofilaments is 21.0+/-3.3 nm MPa-1. Accordingly, the stiffness of the ensemble of myosin heads attached in the hs is 45.5+/-1.7 kPa nm-1 in isometric contraction at saturating [Ca2+] (e0), and in rigor (er) it rises to 138.9+/-21.2 kPa nm-1. Epsilon, calculated from er and the lattice molecular dimensions, is 1.21+/-0.18 pN nm-1. epsilon estimated, using a thermodynamic approach, from the relation of T0 at saturating [Ca2+] versus the reciprocal of absolute temperature is 1.25+/-0.14 pN nm-1, similar to that estimated for fibers in rigor. Consequently, the ratio e0/er (0.33+/-0.05) can be used to estimate the fraction of attached heads during isometric contraction at saturating [Ca2+]. If the osmotic agent dextran T-500 (4 g/100 ml) is used to reduce the lateral filament spacing of the relaxed fiber to the value before skinning, both e0 and er increase by approximately 40%. Epsilon becomes approximately 1.7 pN nm-1 and the fraction and the force of myosin heads attached in the isometric contraction remain the same as before dextran application. The finding that the fraction of myosin heads attached to actin in an isometric contraction is 0.33 rules out the hypothesis of multiple mechanical cycles per ATP hydrolyzed.

Picosecond passively mode-locked mid-infrared fiber laser

NASA Astrophysics Data System (ADS)

Wei, C.; Zhu, X.; Norwood, R. A.; Kieu, K.; Peyghambarian, N.

2013-02-01

Mode-locked mid-infrared (mid-IR) fiber lasers are of increasing interest due to their many potential applications in spectroscopic sensors, infrared countermeasures, laser surgery, and high-efficiency pump sources for nonlinear wavelength convertors. Er3+-doped ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF) fiber lasers, which can emit mid-IR light at 2.65-2.9 μm through the transition from the upper energy level 4I11/2 to the lower laser level 4I13/2, have attracted much attention because of their broad emission range, high optical efficiency, and the ready availability of diode pump lasers at the two absorption peaks of Er3+ ions (975 nm and 976 nm). In recent years, significant progress on high power Er3+- doped ZBLAN fiber lasers has been achieved and over 20 watt cw output at 2.8 μm has been demonstrated; however, there has been little progress on ultrafast mid-IR ZBLAN fiber lasers to date. We report a passively mode-locked Er3+- doped ZBLAN fiber laser in which a Fe2+:ZnSe crystal was used as the intracavity saturable absorber. Fe2+:ZnSe is an ideal material for mid-IR laser pulse generation because of its large saturable absorption cross-section and small saturation energy along with the excellent opto-mechanical (damage threshold ~2 J/cm2) and physical characteristics of the crystalline ZnSe host. A 1.6 m double-clad 8 mol% Er3+-doped ZBLAN fiber was used in our experiment. The fiber core has a diameter of 15 μm and a numerical aperture (NA) of 0.1. The inner circular cladding has a diameter of 125 μm and an NA of 0.5. Both continuous-wave and Q-switched mode-locking pulses at 2.8 μm were obtained. Continuous-wave mode locking operation with a pulse duration of 19 ps and an average power of 51 mW were achieved when a collimated beam traversed the Fe2+:ZnSe crystal. When the cavity was modified to provide a focused beam at the Fe2+:ZnSe crystal, Q-switched mode-locked operation with a pulse duration of 60 ps and an average power of 4.6 mW was achieved. More powerful and narrower pulses are expected if the dispersion of the cavity can be properly managed.

Carbon fiber composite molecular sieve electrically regenerable air filter media

DOEpatents

Wilson, K.A.; Burchell, T.D.; Judkins, R.R.

1998-10-27

An electrically regenerable gas filter system includes a carbon fiber composite molecular sieve (CFCMS) filter medium. After a separate medium-efficiency pre-filter removes particulate from the supply air stream, the CFCMS filter sorbs gaseous air pollutants before the air is recirculated to the space. When saturated, the CFCMS media is regenerated utilizing a low-voltage current that is caused to pass through the filter medium. 3 figs.

Ytterbium-doped fiber laser passively mode locked by few-layer Molybdenum Disulfide (MoS2) saturable absorber functioned with evanescent field interaction

PubMed Central

Du, Juan; Wang, Qingkai; Jiang, Guobao; Xu, Changwen; Zhao, Chujun; Xiang, Yuanjiang; Chen, Yu; Wen, Shuangchun; Zhang, Han

2014-01-01

By coupling few-layer Molybdenum Disulfide (MoS2) with fiber-taper evanescent light field, a new type of MoS2 based nonlinear optical modulating element had been successfully fabricated as a two-dimensional layered saturable absorber with strong light-matter interaction. This MoS2-taper-fiber device is not only capable of passively mode-locking an all-normal-dispersion ytterbium-doped fiber laser and enduring high power laser excitation (up to 1 W), but also functions as a polarization sensitive optical modulating component (that is, different polarized light can induce different nonlinear optical response). Thanks to the combined advantages from the strong nonlinear optical response in MoS2 together with the sufficiently-long-range interaction between light and MoS2, this device allows for the generation of high power stable dissipative solitons at 1042.6 nm with pulse duration of 656 ps and a repetition rate of 6.74 MHz at a pump power of 210 mW. Our work may also constitute the first example of MoS2-enabled wave-guiding photonic device, and potentially give some new insights into two-dimensional layered materials related photonics. PMID:25213108

Wavelength tunable ultrafast fiber laser via reflective mirror with taper structure.

PubMed

Fang, Li; Huang, Chuyun; Liu, Ting; Gogneau, Noelle; Bourhis, Eric; Gierak, Jacques; Oudar, Jean-Louis

2016-12-20

Laser sources with a controllable flexible wavelength have found widespread applications in optical fiber communication, optical sensing, and microscopy. Here, we report a tunable mode-locked fiber laser using a graphene-based saturable absorber and a tapered mirror as an end mirror in the cavity. The phase layer in the mirror is precisely etched by focused ion beam (FIB) milling technology, and the resonant wavelength of the mirror shifts correspond to the different etch depths. By scanning the tapered mirror mechanically, the center wavelength of a mode-locked fiber laser can be continuously tuned from 1562 to 1532 nm, with a pulse width in the sub-ps level and repetition rate of 27 MHz.

152 fs nanotube-mode-locked thulium-doped all-fiber laser

PubMed Central

Wang, Jinzhang; Liang, Xiaoyan; Hu, Guohua; Zheng, Zhijian; Lin, Shenghua; Ouyang, Deqin; Wu, Xu; Yan, Peiguang; Ruan, Shuangchen; Sun, Zhipei; Hasan, Tawfique

2016-01-01

Ultrafast fiber lasers with broad bandwidth and short pulse duration have a variety of applications, such as ultrafast time-resolved spectroscopy and supercontinuum generation. We report a simple and compact all-fiber thulium-doped femtosecond laser mode-locked by carbon nanotubes. The oscillator operates in slightly normal cavity dispersion at 0.055 ps2, and delivers 152 fs pulses with 52.8 nm bandwidth and 0.19 nJ pulse energy. This is the shortest pulse duration and the widest spectral width demonstrated from Tm-doped all-fiber lasers based on 1 or 2 dimensional nanomaterials, underscoring their growing potential as versatile saturable absorber materials. PMID:27374764

Mid-infrared passively switched pulsed dual wavelength Ho3+-doped fluoride fiber laser at 3 μm and 2 μm

PubMed Central

Li, Jianfeng; Luo, Hongyu; Wang, Lele; Liu, Yong; Yan, Zhijun; Zhou, Kaiming; Zhang, Lin; Turistsyn, Sergei K.

2015-01-01

Cascade transitions of rare earth ions involved in infrared host fiber provide the potential to generate dual or multiple wavelength lasing at mid-infrared region. In addition, the fast development of saturable absorber (SA) towards the long wavelengths motivates the realization of passively switched mid-infrared pulsed lasers. In this work, by combing the above two techniques, a new phenomenon of passively Q-switched ~3 μm and gain-switched ~2 μm pulses in a shared cavity was demonstrated with a Ho3+-doped fluoride fiber and a specifically designed semiconductor saturable absorber (SESAM) as the SA. The repetition rate of ~2 μm pulses can be tuned between half and same as that of ~3 μm pulses by changing the pump power. The proposed method here will add new capabilities and more flexibility for generating mid-infrared multiple wavelength pulses simultaneously that has important potential applications for laser surgery, material processing, laser radar, and free-space communications, and other areas. PMID:26041105

Sub-200 femtosecond dispersion-managed soliton ytterbium-doped fiber laser based on carbon nanotubes saturable absorber.

PubMed

Hou, Lei; Guo, Hongyu; Wang, Yonggang; Sun, Jiang; Lin, Qimeng; Bai, Yang; Bai, Jintao

2018-04-02

Ultrafast fiber laser light sources attract enormous interest due to the booming applications they are enabling, including long-distance communication, optical metrology, detecting technology of infra-biophotons, and novel material processing. In this paper, we demonstrate 175 fs dispersion-managed soliton (DMS) mode-locked ytterbium-doped fiber (YDF) laser based on single-walled carbon nanotubes (SWCNTs) saturable absorber (SA). The output DMSs have been achieved with repetition rate of 21.2 MHz, center wavelength of 1025.5 nm, and a spectral width of 32.7 nm. The operation directly pulse duration of 300 fs for generated pulse is the reported shortest pulse width for broadband SA based YDF lasers. By using an external grating-based compressor, the pulse duration could be compressed down to 175 fs. To the best of our knowledge, it is the shortest pulse duration obtained directly from YDF laser based on broadband SAs. In this paper, SWCNTs-SA has been utilized as the key optical component (mode locker) and the grating pair providing negative dispersion acts as the dispersion controller.

2μm all fiber multi-wavelength Tm/Ho co-doped fiber laser

NASA Astrophysics Data System (ADS)

Zhang, Junhong; Jiang, Qiuxia; Wang, Xiaofa

2017-10-01

A 2 μm all fiber multi-wavelength Tm/Ho co-doped fiber laser based on a simple ring cavity is experimentally demonstrated. Compared with other 2 μm multi-wavelength Tm/Ho co-doped fiber lasers, the multi-wavelength fiber laser is obtained by the gain saturation effect and inhomogeneous broadening effect without any frequency selector component, filter component or polarization-dependent component. When the pump power is about 304 mW, the fiber laser enters into single-wavelength working state around 1967.76 nm. Further increasing the pump power to 455 mW, a stable dual-wavelength laser is obtained at room temperature. The bimodal power difference between λ1 and λ2 is 5.528 dB. The fluctuations of wavelength and power are less than 0.03 nm and 0.264 dB in an hour, which demonstrates that the multi-wavelength fiber laser works at a stable state. Furthermore, a research about the relationship between the pump power and the output spectra has been made.

Spectral dynamics of square pulses in passively mode-locked fiber lasers

NASA Astrophysics Data System (ADS)

Semaan, Georges; Komarov, Andrey; Niang, Alioune; Salhi, Mohamed; Sanchez, François

2018-02-01

We investigate experimentally and numerically the spectral dynamics of square pulses generated in passively mode-locked fiber lasers under the dissipative soliton resonance. The features of the transition from the single-peak spectral profile to the doublet spectrum with increasing pump power are studied. The used master equation takes into account the gain saturation, the quadratic frequency dispersion of the gain and the refractive index, and the cubic-quintic nonlinearity of the losses and refractive index. Experimental data are obtained for an Er:Yb-doped fiber ring laser. The theoretical and experimental results are in good agreement with each other.

Low-loss flake-graphene saturable absorber mirror for laser mode-locking at sub-200-fs pulse duration

NASA Astrophysics Data System (ADS)

Cunning, B. V.; Brown, C. L.; Kielpinski, D.

2011-12-01

Saturable absorbers are a key component for mode-locking femtosecond lasers. Polymer films containing graphene flakes have recently been used in transmission as laser mode-lockers but suffer from high nonsaturable loss, limiting their application in low-gain lasers. Here, we present a saturable absorber mirror based on a film of pure graphene flakes. The device is used to mode lock an erbium-doped fiber laser, generating pulses with state-of-the-art, sub-200-fs duration. The laser characteristic indicates that the film exhibits low nonsaturable loss (13% per pass) and large absorption modulation depth (45% of low-power absorption).

Ultrahigh precision nonlinear reflectivity measurement system for saturable absorber mirrors with self-referenced fluence characterization.

PubMed

Orsila, Lasse; Härkönen, Antti; Hyyti, Janne; Guina, Mircea; Steinmeyer, Günter

2014-08-01

Measurement of nonlinear optical reflectivity of saturable absorber devices is discussed. A setup is described that enables absolute accuracy of reflectivity measurements better than 0.3%. A repeatability within 0.02% is shown for saturable absorbers with few-percent modulation depth. The setup incorporates an in situ knife-edge characterization of beam diameters, making absolute reflectivity estimations and determination of saturation fluences significantly more reliable. Additionally, several measures are discussed to substantially improve the reliability of the reflectivity measurements. At its core, the scheme exploits the limits of state-of-the-art digital lock-in technology but also greatly benefits from a fiber-based master-oscillator power-amplifier source, the use of an integrating sphere, and simultaneous comparison with a linear reflectivity standard.

Modulational-instability-induced supercontinuum generation with saturable nonlinear response

NASA Astrophysics Data System (ADS)

Raja, R. Vasantha Jayakantha; Porsezian, K.; Nithyanandan, K.

2010-07-01

We theoretically investigate the supercontinuum generation (SCG) on the basis of modulational instability (MI) in liquid-core photonic crystal fibers (LCPCF) with CS2-filled central core. The effect of saturable nonlinearity of LCPCF on SCG in the femtosecond regime is studied using an appropriately modified nonlinear Schrödinger equation. We also compare the MI induced spectral broadening with SCG obtained by soliton fission. To analyze the quality of the pulse broadening, we study the coherence of the SC pulse numerically. It is evident from the numerical simulation that the response of the saturable nonlinearity suppresses the broadening of the pulse. We also observe that the MI induced SCG in the presence of saturable nonlinearity degrades the coherence of the SCG pulse when compared to unsaturated medium.

Modulational-instability-induced supercontinuum generation with saturable nonlinear response

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

Raja, R. Vasantha Jayakantha; Porsezian, K.; Nithyanandan, K.

2010-07-15

We theoretically investigate the supercontinuum generation (SCG) on the basis of modulational instability (MI) in liquid-core photonic crystal fibers (LCPCF) with CS{sub 2}-filled central core. The effect of saturable nonlinearity of LCPCF on SCG in the femtosecond regime is studied using an appropriately modified nonlinear Schroedinger equation. We also compare the MI induced spectral broadening with SCG obtained by soliton fission. To analyze the quality of the pulse broadening, we study the coherence of the SC pulse numerically. It is evident from the numerical simulation that the response of the saturable nonlinearity suppresses the broadening of the pulse. We alsomore » observe that the MI induced SCG in the presence of saturable nonlinearity degrades the coherence of the SCG pulse when compared to unsaturated medium.« less

Distributed optical fiber-based monitoring approach of spatial seepage behavior in dike engineering

NASA Astrophysics Data System (ADS)

Su, Huaizhi; Ou, Bin; Yang, Lifu; Wen, Zhiping

2018-07-01

The failure caused by seepage is the most common one in dike engineering. As to the characteristics of seepage in dike, such as longitudinal extension engineering, the randomness, strong concealment and small initial quantity order, by means of distributed fiber temperature sensor system (DTS), adopting an improved optical fiber layer layout scheme, the location of initial interpolation point of the saturation line is obtained. With the barycentric Lagrange interpolation collocation method (BLICM), the infiltrated surface of dike full-section is generated. Combined with linear optical fiber monitoring seepage method, BLICM is applied in an engineering case, which shows that a real-time seepage monitoring technique is presented in full-section of dike based on the combination method.

A High-Carbohydrate, High-Fiber, Low-Fat Diet Results in Weight Loss among Adults at High Risk of Type 2 Diabetes.

PubMed

Sylvetsky, Allison C; Edelstein, Sharon L; Walford, Geoffrey; Boyko, Edward J; Horton, Edward S; Ibebuogu, Uzoma N; Knowler, William C; Montez, Maria G; Temprosa, Marinella; Hoskin, Mary; Rother, Kristina I; Delahanty, Linda M

2017-11-01

Background: Weight loss is a key factor in reducing diabetes risk. The Diabetes Prevention Program (DPP) is a completed clinical trial that randomly assigned individuals at high risk of diabetes to a placebo (PLBO), metformin (MET), or intensive lifestyle intervention (ILS) group, which included physical activity (PA) and reduced dietary fat intake. Objective: We aimed to evaluate the associations between diet and weight at baseline and to identify specific dietary factors that predicted weight loss among DPP participants. Methods: Diet was assessed by a food frequency questionnaire. The associations between intakes of macronutrients and various food groups and body weight among DPP participants at baseline were assessed by linear regression, adjusted for race/ethnicity, age, sex, calorie intake, and PA. Models that predicted weight loss at year 1 were adjusted for baseline weight, change in calorie intake, and change in PA and stratified by treatment allocation (MET, ILS, and PLBO). All results are presented as estimates ± SEs. Results: A total of 3234 participants were enrolled in the DPP; 2924 had completed dietary data (67.5% women; mean age: 50.6 ± 10.7 y). Adjusted for calorie intake, baseline weight was negatively associated with carbohydrate intake (-1.14 ± 0.18 kg body weight/100 kcal carbohydrate, P < 0.0001) and, specifically, dietary fiber (-1.26 ± 0.28 kg/5 g fiber, P < 0.0001). Baseline weight was positively associated with total fat (1.25 ± 0.21 kg/100 kcal, P < 0.0001), saturated fat (1.96 ± 0.46 kg/100 kcal, P < 0.0001), and protein (0.21 ± 0.05 kg/100 kcal, P < 0.0001). For all groups, weight loss after 1 y was associated with increases in carbohydrate intake, specifically dietary fiber, and decreases in total fat and saturated fat intake. Conclusions: Higher carbohydrate consumption among DPP participants, specifically high-fiber carbohydrates, and lower total and saturated fat intake best predicted weight loss when adjusted for changes in calorie intake. Our results support the benefits of a high-carbohydrate, high-fiber, low-fat diet in the context of overall calorie reduction leading to weight loss, which may prevent diabetes in high-risk individuals. This trial was registered at clinicaltrials.gov as NCT00004992. © 2017 American Society for Nutrition.

High-power Q-switched erbium-ytterbium codoped fiber laser using multiwalled carbon nanotubes saturable absorber

NASA Astrophysics Data System (ADS)

Ab Razak, Mohd Zulhakimi; Saleh, Zatul Saliza; Ahmad, Fauzan; Anyi, Carol Livan; Harun, Sulaiman W.; Arof, Hamzah

2016-10-01

Due to an enormous potential of pulsed lasers in applications such as manufacturing, metrology, environmental sensing, and biomedical diagnostics, a high-power and stable Q-switched erbium-ytterbium codoped double-clad fiber laser (EYDFL) incorporating of multiwall carbon nanotubes (MWCNTs) saturable absorber (SA) made based on polyvinyl alcohol (PVA) with a 3∶2 ratio is demonstrated. The SA was fabricated by mixing a dilute PVA solution with an MWCNTs homogeneous solution. Subsequently, the mixture was sonicated and centrifuged to produce a homogeneous suspension that was left to dry at room temperature to form the MWCNTs-PVA film. The SA was formed by inserting the film between a pair of FC/PC fiber connectors. Then, it was integrated into the EYDFL's ring cavity, which uses a 5-m-long erbium-ytterbium codoped fiber (EYDF). The lasing threshold for the Q-switched EYDFL was at 330 mW. At the maximum available pump power of 900 mW, the proposed EYDFL produced Q-switched pulses with a repetition rate of 74.85 kHz, pulsewidth of ˜3.6 μs, and an average output power of about 5 mW. The maximum energy per pulse of ˜85 nJ was obtained at pump power of ˜700 mW with peak power of 21 mW.

Vector rectangular-shape laser based on reduced graphene oxide interacting with a long fiber taper.

PubMed

Gao, Lei; Zhu, Tao; Huang, Wei; Zeng, Jing

2014-10-01

A vector dual-wavelength rectangular-shape laser (RSL) based on a long fiber taper deposited with reduced graphene oxide is proposed, where nonlinearity is enhanced due to a large evanescent-field-interacting length and strong field confinement of an 8 mm fiber taper with a waist diameter of 4 μm. Graphene flakes are deposited uniformly on the taper waist with light pressure effect, so this structure guarantees both excellent saturable absorption and high nonlinearity. The RSL with a repetition rate of 7.9 MHz shows fast polarization switching in two orthogonal polarization directions, and temporal and spectral characteristics are investigated.

High-Energy Passive Mode-Locking of Fiber Lasers

PubMed Central

Ding, Edwin; Renninger, William H.; Wise, Frank W.; Grelu, Philippe; Shlizerman, Eli; Kutz, J. Nathan

2012-01-01

Mode-locking refers to the generation of ultrashort optical pulses in laser systems. A comprehensive study of achieving high-energy pulses in a ring cavity fiber laser that is passively mode-locked by a series of waveplates and a polarizer is presented in this paper. Specifically, it is shown that the multipulsing instability can be circumvented in favor of bifurcating to higher-energy single pulses by appropriately adjusting the group velocity dispersion in the fiber and the waveplate/polarizer settings in the saturable absorber. The findings may be used as practical guidelines for designing high-power lasers since the theoretical model relates directly to the experimental settings. PMID:22866059

Cladding-pumped passively mode-locked fiber laser generating femtosecond and picosecond pulses

NASA Astrophysics Data System (ADS)

Fermann, M. E.; Harter, D.; Minelly, J. D.; Vienne, G. G.

1996-07-01

Passively mode-locked fiber lasers cladding pumped by broad-area diode-laser arrays are described. With a dispersion-compenstated erbium-ytterbium fiber oscillator, 200-fs pulses with pulse energies up to 100 pJ are generated at a wavelength of 1560 nm. In a highly dispersive cavity, pulse widths of 3 ps with pulse energies up to 1 nJ are obtained. A saturable absorber is used for pulse startup, whereas nonlinear polarization evolution is exploited for steady-state pulse shaping. An environmentally stable design is ensured by use of a compensation scheme for linear polarization drifts in the cavity.

Cladding-pumped passively mode-locked fiber laser generating femtosecond and picosecond pulses.

PubMed

Fermann, M E; Harter, D; Minelly, J D; Vienne, G G

1996-07-01

Passively mode-locked fiber lasers cladding pumped by broad-area diode-laser arrays are described. With a dispersion-compenstated erbium-ytterbium fiber oscillator, 200-fs pulses with pulse energies up to 100 pJ are generated at a wavelength of 1560 nm. In a highly dispersive cavity, pulse widths of 3 ps with pulse energies up to 1 nJ are obtained. A saturable absorber is used for pulse startup, whereas nonlinear polarization evolution is exploited for steady-state pulse shaping. An environmentally stable design is ensured by use of a compensation scheme for linear polarization drifts in the cavity.

Switchable dual-wavelength single-longitudinal-mode erbium fiber laser utilizing a dual-ring scheme with a saturable absorber

NASA Astrophysics Data System (ADS)

Yang, Zi-Qing; Huang, Tzu-Jung; Chang, Yao-Jen; Yeh, Chien-Hung; Chow, Chi-Wai; Chen, Jing-Heng; Chen, Kun-Huang

2018-06-01

In this work, we propose and demonstrate a switchable dual-wavelength erbium-doped fiber (EDF) ring laser with stable single-longitudinal-mode (SLM) output. Here, a dual-ring (DR) structure with an unpumped EDF of 2 m is designed to achieve SLM oscillation. Five fiber Bragg gratings (FBGs) are applied in the laser cavity serving as the reflective element to generate different dual-wavelength outputs. In the measurement, six sets of generated dual-wavelengths with various mode-spacing (Δλ) can be achieved via the five FBGs. Additionally, the stability performance of the proposed EDF DR laser is also demonstrated.

Stable passive optical clock generation in SOA-based fiber lasers.

PubMed

Wang, Jing-Yun; Lin, Kuei-Huei; Chen, Hou-Ren

2015-02-15

Stable optical pulse trains are obtained from 1.3-μm and 1.5-μm semiconductor optical amplifier (SOA)-based fiber lasers using passive optical technology. The waveforms depend on SOA currents, and the repetition rates can be tuned by varying the relative length of sub-cavities. The output pulse trains of these SOA-based fiber lasers are stable against intracavity polarization adjustment and environmental perturbation. The optical clock generation is explained in terms of mode competition, self-synchronization, and SOA saturation. Without resorting to any active modulation circuits or devices, the technology used here is simple and may find various applications in the future.

Titanium Dioxide (TiO2) film as a new saturable absorber for generating mode-locked Thulium-Holmium doped all-fiber laser

NASA Astrophysics Data System (ADS)

Mohd Rusdi, Muhammad Farid; Latiff, Anas Abdul; Paul, Mukul Chandra; Das, Shyamal; Dhar, Anirban; Ahmad, Harith; Harun, Sulaiman Wadi

2017-03-01

We report the generation of mode-locked thulium-holmium doped fiber laser (THDFL) at 1979 nm. This is a first demonstration of mode-locked by using Titanium Dioxide (TiO2) film as a saturable absorber (SA). A piece of 1 mm×1 mm TiO2 film was sandwiched in between two fiber ferrule in the cavity. Fabrication process of TiO2 film incorporated a TiO2 and a polyvinyl alcohol (PVA). The stable 9 MHz repetition rate of mode-locked mode operation with 58 dB SNR was generated under pump power of 902-1062 mW. At maximum pump power, the mode-locked THDFL has output power and pulse energy of 15 mW and 1.66 nJ, respectively. Our results demonstrate the TiO2 can be used promisingly in ultrafast photonics applications.

High energy Er-doped Q-switched fiber laser with WS2 saturable absorber

NASA Astrophysics Data System (ADS)

Li, Lu; Wang, Yonggang; Wang, Zhen Fu; Wang, Xi; Yang, Guowen

2018-01-01

The report presents a stable Q-switched Er-doped fiber (EDF) laser with WS2-based saturable absorber (SA). The SA is obtained by mixing WS2 dispersion with polyvinyl alcohol (PVA) into polystyrene cells, and then evaporating them to form WS2/PVA film. The modulation depth (MD) of WS2/PVA is 2% and the saturable intensity (Isat) is 27.2 MW/cm2. Employing the WS2/PVA film into EDF laser cavity, stable Q-switched operation is achieved with central wavelength of 1560 nm. The repetition rate can be tuned from 16.15 to 60.88 kHz with increasing pump power from 30 to 320 mW. The single pulse energy increases from 82 to 195 nJ and then decreases down to 156 nJ with increasing pump power from 30 to 320 mW. The pulse width shows the same variation trend. The shortest pulse duration of 2.396 μs and the maximum single pulse energy of 195 nJ are obtained at the pump power of 220 mW. To the best of our knowledge, 195 nJ is the largest single pulse energy at 1.55 μm region with TMDs as Q-switcher. The signal-to-noise ratio (SNR) is measured to be 60 dB at the pump power of 130 mW. The long term stability of working is good too. The experimental results evidently show that the WS2/PVA SA can work as a promising Q-switcher for high power fiber lasers.

A practical topological insulator saturable absorber for mode-locked fiber laser

PubMed Central

Yan, Peiguang; Lin, Rongyong; Ruan, Shuangchen; Liu, Aijiang; Chen, Hao; Zheng, Yuequn; Chen, Sifan; Guo, Chunyu; Hu, Juguang

2015-01-01

A novel saturable absorber (SA) was fabricated by coating the topological insulator (TI) film on microfiber using pulsed laser deposition (PLD) method. The TISA device had an insertion loss of ~1.25 dB, a saturable intensity of 26.7 MW/cm2, a modulation depth of ~5.7%, and a nonsaturable loss of 20.5%. Upon employing this SA device, we established a passively mode-locked EDFL and achieved nearly free-chirped soliton pulse with 286 fs of pulse duration and >73 dB of signal to noise ratio (SNR). This result clearly evidences that the PLD is an effective scheme for practical SA device fabrication. PMID:25732598

Stable high-power saturable absorber based on polymer-black-phosphorus films

NASA Astrophysics Data System (ADS)

Mao, Dong; Li, Mingkun; Cui, Xiaoqi; Zhang, Wending; Lu, Hua; Song, Kun; Zhao, Jianlin

2018-01-01

Black phosphorus (BP), a rising two-dimensional material with a layer-number-dependent direct bandgap of 0.3-1.5 eV, is very interesting for optoelectronics applications from near- to mid-infrared wavebands. In the atmosphere, few-layer BP tends to be oxidized or degenerated during interacting with lasers. Here, we fabricate few-layer BP nanosheets based on a liquid exfoliation method using N-methylpyrrolidone as the dispersion liquid. By incorporating BP nanosheets with polymers (polyvinyl alcohol or high-melting-point polyimide), two flexible filmy BP saturable absorbers are fabricated to realize passive mode locking in erbium-doped fiber lasers. The polymer-BP saturable absorber, especially the polyimide-BP saturable absorber, can prevent the oxidation or water-induced etching under high-power laser illuminations, providing a promising candidate for Q-switchers, mode lockers, and light modulators.

Wavelength tunable L Band polarization-locked vector soliton fiber laser based on SWCNT-SA and CFBG

NASA Astrophysics Data System (ADS)

Yan, Yaxi; Wang, Jiaqi; Wang, Liang; Cheng, Zhenzhou

2018-04-01

Wavelength tunable L-Band polarization-locked vector soliton fiber laser based on single-walled carbon nanotube saturable absorber (SWCNT-SA) and chirped fiber Bragg grating (CFBG) is presented for the first time. By inserting the SWCNT-SA into an all-fiber laser cavity, polarization-locked vector solitons (PLVS) are obtained. The CFBG glued on a plastic cantilever is used for wavelength tuning. By mechanically bending the cantilever, the center wavelength of the PLVS pulses can be continuously tuned from 1606.8 nm to 1614 nm, while the polarization-locked state is kept stable. The properties and dynamics of PLVSs are experimentally investigated and stable PLVS operation including high-order PLVSs is demonstrated. The pulse width and repetition rate are 7.06 ps and 11.9 MHz at a wavelength of 1611 nm, respectively. This work demonstrates the feasibility of using polarization-insensitive CFBG to realize wavelength tuning in PLVS fiber laser.

Switchable and tunable dual-wavelength Er-doped fiber ring laser with single-frequency lasing wavelengths

NASA Astrophysics Data System (ADS)

Zhang, Haiwei; Shi, Wei; Bai, Xiaolei; Sheng, Quan; Xue, Lifang; Yao, Jianquan

2018-02-01

We obtain a switchable and tunable dual-wavelength single-frequency Er-doped ring fiber laser. In order to realize single-longitudinal output, two saturable-absorber-based tracking narrow-band filters are formed in 3- meter-long unpumped Er-doped fiber to narrow the linewidth via using the PM-FBG as a reflection filter. The maximum output power is 2.11 mW centered at 1550.16 nm and 1550.54 nm when the fiber laser operates in dual-wavelength mode. The corresponding linewidths of those two wavelengths are measured to be 769 Hz and 673 Hz, respectively. When the temperature around the PM-FBG is changed from 15 °C to 55 °C, the dual-wavelength single-frequency fiber laser can be tuned from 1550.12 nm to 1550.52 nm and from 1550.49 nm to 1550.82 nm, respectively.

Seawater infiltration effect on thermal degradation of fiber reinforced epoxy composites

NASA Astrophysics Data System (ADS)

Ibrahim, Mohd Haziq Izzuddin bin; Hassan, Mohamad Zaki bin; Ibrahim, Ikhwan; Rashidi, Ahmad Hadi Mohamed; Nor, Siti Fadzilah M.; Daud, Mohd Yusof Md

2018-05-01

Seawater salinity has been associated with the reduction of polymer structure durability. The aim of this study is to investigate the change in thermal degradation of fiber reinforced epoxy composite due to the presence of seawater. Carbon fiber, carbon/kevlar, fiberglass, and jute that reinforced with epoxy resin was laminated through hand-layup technique. Initially, these specimen was sectioned to 5×5 mm dimension, then immersed in seawater and distilled water at room temperature until it has thoroughly saturated. Following, the thermal degradation analysis using Differential Scanning Calorimetry (DSC), the thermic changes due to seawater infiltration was defined. The finding shows that moisture absorption reduces the glass transition temperature (Tg) of fiber reinforced epoxy composite. However, the glass transition temperature (Tg) of seawater infiltrated laminate composite is compareable with distilled water infiltrated laminate composite. The carbon fiber reinfored epoxy has the highest glass transition temperature out of all specimen.

Mode-locked Er-doped fiber laser based on liquid phase exfoliated Sb2Te3 topological insulator

NASA Astrophysics Data System (ADS)

Boguslawski, J.; Sotor, J.; Sobon, G.; Tarka, J.; Jagiello, J.; Macherzynski, W.; Lipinska, L.; Abramski, K. M.

2014-10-01

In this paper, femtosecond pulse generation in an Er-doped fiber laser is reported. The laser is passively mode-locked by an antimony telluride (Sb2Te3) topological insulator (TI) saturable absorber (SA) placed on a side-polished fiber. The Sb2Te3/chitosan suspension used to prepare the SA was obtained via liquid phase exfoliation from bulk Sb2Te3.Ultra-short 449 fs soliton pulses were generated due to the interaction between the evanescent field propagated in the fiber cladding and the Sb2Te3 layers. The optical spectrum is centered at 1556 nm with 6 nm of full-width at half maximum bandwidth. The presented method benefits from a much better repeatability compared to mechanical exfoliation.

Creep of Hi-Nicalon S Ceramic Fiber Tows at 800 deg C in Air and in Silicic Acid-Saturated Steam

DTIC Science & Technology

2015-12-26

earliest recorded instances is that of Egyptian brick making. As far back as approximately 1500 BC, Egyptians added straw to clay for bricks [3]. This...The accuracy of this calculation method depends on the accuracy of amorphous silica viscosity data, which, in turn, are affected by impurities in...the SiC fiber. Lack of availability of viscosity data for crystobalite and tridymite pre- cluded calculation of growth stresses in crystallized silica

Analysis of Wood Structure Connections Using Cylindrical Steel and Carbon Fiber Dowel Pins

NASA Astrophysics Data System (ADS)

Vodiannikov, Mikhail A.; Kashevarova, Galina G., Dr.

2017-06-01

In this paper, the results of the statistical analysis of corrosion processes and moisture saturation of glued laminated timber structures and their joints in corrosive environment are shown. This paper includes calculation results for dowel connections of wood structures using steel and carbon fiber reinforced plastic cylindrical dowel pins in accordance with applicable regulatory documents by means of finite element analysis in ANSYS software, as well as experimental findings. Dependence diagrams are shown; comparative analysis of the results obtained is conducted.

Phase-sensitive fiber-based parametric all-optical switch.

PubMed

Parra-Cetina, Josué; Kumpera, Aleš; Karlsson, Magnus; Andrekson, Peter A

2015-12-28

We experimentally demonstrate, for the first time, an all-optical switch in a phase-sensitive fiber optic parametric amplifier operated in saturation. We study the effect of phase variation of the signal and idler waves on the pump power depletion. By changing the phase of a 0.9 mW signal/idler pair wave by π/2 rad, a pump power extinction ratio of 30.4 dB is achieved. Static and dynamic characterizations are also performed and time domain results presented.

Switchable dual-wavelength SLM narrow linewidth fiber laser based on nonlinear amplifying loop mirror

NASA Astrophysics Data System (ADS)

Fu, Pan; Feng, Xiao-qiang; Lu, Baole; Qi, Xin-yuan; Chen, Haowei; Sun, Bo; Jiang, Man; Wang, Kaile; Bai, Jintao

2018-01-01

We demonstrate a stable switchable dual-wavelength single longitudinal mode (SLM) narrow linewidth ytterbium-doped fiber (YDF) laser using a nonlinear amplifying fiber loop mirror (NALM) at 1064 nm. The NALM of intensity-dependent transmission acts as a saturable absorber filter and an amplitude equalizer to suppress mode competition and the fiber Bragg grating (FBG) pair is used as one wavelength selection component. By properly adjusting the polarization controllers (PCs), the switchable dual-wavelength SLM fiber laser can be operated steadily at room temperature. The optical signal-to-noise ratio (OSNR) is better than 50 dB for both lasing wavelengths. Meanwhile, the linewidth of the fiber laser for each wavelength is approximate 17.07 kHz and 18.64 kHz with a 20 dB linewidth, which means the laser linewidth is approximate 853 Hz and 932 Hz FWHM. Correspondingly, the measured relative intensity noise (RIN) is less than -120 dB/Hz at frequencies over 5.0 MHz.

Self-organized dynamics in local load-sharing fiber bundle models.

PubMed

Biswas, Soumyajyoti; Chakrabarti, Bikas K

2013-10-01

We study the dynamics of a local load-sharing fiber bundle model in two dimensions under an external load (which increases with time at a fixed slow rate) applied at a single point. Due to the local load-sharing nature, the redistributed load remains localized along the boundary of the broken patch. The system then goes to a self-organized state with a stationary average value of load per fiber along the (increasing) boundary of the broken patch (damaged region) and a scale-free distribution of avalanche sizes and other related quantities are observed. In particular, when the load redistribution is only among nearest surviving fiber(s), the numerical estimates of the exponent values are comparable with those of the Manna model. When the load redistribution is uniform along the patch boundary, the model shows a simple mean-field limit of this self-organizing critical behavior, for which we give analytical estimates of the saturation load per fiber values and avalanche size distribution exponent. These are in good agreement with numerical simulation results.

Highly improved Uv resistance and composite interfacial properties of aramid fiber via iron (III) coordination

NASA Astrophysics Data System (ADS)

Cheng, Zheng; Hong, Dawei; Dai, Yu; Jiang, Chan; Meng, Chenbo; Luo, Longbo; Liu, Xiangyang

2018-03-01

The poor Uv stability and weak interfacial adhesion are considered as the bottleneck problems for further application of aramid fiber. Herein, a new strategy, Fe3+ coordination, was reported for aramid fiber to simultaneous improve its Uv resistance and composite interfacial shear strength. Fe3+ was introduced onto aramid fiber by coordinating with benzimidazole unit of fiber structure. It can reach a doping capacity of as high as 1516ug/g fiber, and the fiber surface is saturatedly covered with Fe3+. The chemical structure of Fe3+-benzimidazole brings about strong metal-enhanced fluorescence emission effect, which, in turn, greatly raises its Uv stability. Owing to the Fe3+ coordination, the tensile strength of Fe-coordinated fiber could preserve as high as 96% after Uv irradiation, compared with 73% of untreated fiber. Meanwhile, the introduction of Fe3+ improves the surface polarity of aramid fiber and consequently leads to the increase of the composite interfacial shear strength by 39%. It is believed that the Fe-coordinated fiber integrates the advantages of easy production, cost-effective and increased Uv stability, as well as high composite interfacial adhesion, and can be used as promising enhancement for the advanced composite material in harsh environment.

Research on polarization vector characteristics in a microfiber-based graphene fiber laser

NASA Astrophysics Data System (ADS)

Han, Mengmeng; Zhang, Shumin; Li, Xingliang; Han, Huiyun; Liu, Jingmin; Yan, Dan

2016-11-01

We experimentally investigated the polarization vector characteristics in an Er-doped fiber laser based on graphene that was deposited on microfiber. A variety of dynamic states, including polarization locked fundamental soliton, and polarization domain wall square pulses and their harmonic mode locked counterparts have all been observed with different pump powers and polarization states. These results indicated that the microfiber-based graphene not only could act as a saturable absorber but also could provide high nonlinearity, which is favorable for the cross coupling between the two orthogonal polarization components. It was worth to mention that it is the first time to obtain the polarization domain wall solitons in a mode locked fiber laser.

In-band pumped Q-switched fiber laser based on monolayer graphene

NASA Astrophysics Data System (ADS)

Wu, Hanshuo; Wu, Jian; Xiao, Hu; Leng, Jinyong; Xu, Jiangming; Zhou, Pu

2017-06-01

We propose and demonstrate an in-band pumped all-fiberized passively Q-switched laser emitting at 1080 nm. A single mode 1030 nm fiber laser is used as the pump source, while a 2D material, CVD-grown monolayer graphene, is adopted as a saturable absorber inside the ring cavity. The repetition rate of the output pulses can be varied from 12.74 to 24.6 kHz with the pulse duration around 12 µs. The maximum average output power is 34.25 mW, with the pulse energy of 1.392 µJ. This work proves the practicability of achieving passively Q-switched operation via in-band pump.

Ultrafast nonlinear optical properties of thin-solid DNA film and their application as a saturable absorber in femtosecond mode-locked fiber laser

PubMed Central

Khazaeinezhad, Reza; Hosseinzadeh Kassani, Sahar; Paulson, Bjorn; Jeong, Hwanseong; Gwak, Jiyoon; Rotermund, Fabian; Yeom, Dong-Il; Oh, Kyunghwan

2017-01-01

A new extraordinary application of deoxyribonucleic acid (DNA) thin-solid-film was experimentally explored in the field of ultrafast nonlinear photonics. Optical transmission was investigated in both linear and nonlinear regimes for two types of DNA thin-solid-films made from DNA in aqueous solution and DNA-cetyltrimethylammonium chloride (CTMA) in an organic solvent. Z-scan measurements revealed a high third-order nonlinearity with n2 exceeding 10−9 at a wavelength of 1570 nm, for a nonlinarity about five orders of magnitude larger than that of silica. We also demonstrated ultrafast saturable absorption (SA) with a modulation depth of 0.43%. DNA thin solid films were successfully deposited on a side-polished optical fiber, providing an efficient evanescent wave interaction. We built an organic-inorganic hybrid all-fiber ring laser using DNA film as an ultrafast SA and using Erbium-doped fiber as an efficient optical gain medium. Stable transform-limited femtosecond soliton pulses were generated with full width half maxima of 417 fs for DNA and 323 fs for DNA-CTMA thin-solid-film SAs. The average output power was 4.20 mW for DNA and 5.46 mW for DNA-CTMA. Detailed conditions for DNA solid film preparation, dispersion control in the laser cavity and subsequent characteristics of soliton pulses are discussed, to confirm unique nonlinear optical applications of DNA thin-solid-film. PMID:28128340

A novel optical fiber biochemical sensor based on long period grating

NASA Astrophysics Data System (ADS)

Mao, Xianhui; Liao, Yanbiao; Zhang, Min; Lai, Shurong; Yin, Haibo

2007-09-01

In this paper, our present work, which aimed at investigating a novel optical fiber biochemical sensor based on long period grating (LPG), is introduced. Biochemical sensor is one of the most attractive fields of sensor research, especially with the development and occurrence of all kinds of novel theory and technology such as LPG. When there is a refraction index periodic perturbation, the guiding mode and cladding mode in LPG couple with each other. This make the LPG is sensitive to the ambient refractive index. This means it can be a novel bio-chemical sensor when it is applied in the fields of biochemistry. After investigating the principle of coupling in LPG, where the formulas of resonance wave length and band width are induced by 3-layer step index model, we developed an optical fiber biochemical sensor. The structure of its probe is designed by coating some function films whose thickness is between several tens and several hundreds nanometers on the cladding of optical fiber. Experiments of monitoring the saline separateness process of Bovine Serum Albumin (BSA) and Mice-Immunoglobulin G (M-IgG) by using the developed LPG sensor have been done. The monitoring indicated that for the BSA, the saline separateness occurs when the saturation is between 50% and 60%, for the M-IgG, the percentage is between 30%-40%. Besides the monitoring, the experiments could also analyze the effects of protein type (different molecule structure), protein consistency and saline saturation to saline separateness. The experimental results show that the optical fiber biochemical sensor based on LPG has many advantages such as simple structure, high sensitivity and miniature. It has a promising future in many research fields and application fields.

Stabilized single-longitudinal-mode erbium fibre laser employing silicon-micro-ring resonator and saturable absorber

NASA Astrophysics Data System (ADS)

Hsu, Yung; Yeh, Chien-Hung; Chow, Chi-Wai; Chang, Yuan-Chia; Cheng, Hao-Yun

2018-07-01

In the paper, a wavelength-tunable erbium-doped fiber (EDF) ring laser with stable single-longitudinal-mode (SLM) oscillation is proposed and investigated. Here, a silicon-micro-ring-resonator can be applied in a laser cavity for tuning wavelength in the C-band range. To complete the SLM oscillation, an unpumped EDF-based saturable absorber is used to act as ultra-narrowband filter for suppressing other oscillation modes. Additionally, the output stabilities of power and wavelength in the proposed EDF ring laser are also executed and discussed.

Enhanced photocatalytic activity of wool fibers having titanium dioxide nanoparticles formed inside their cortex

NASA Astrophysics Data System (ADS)

Zhang, Hui; Sun, Runjun; Wu, Hailiang; Mao, Ningtao

2018-07-01

A wool-TiO2 nanoparticle composite material having TiO2 nanoparticles both infiltrated in the matrix between macrofibrils inside cortical cells of wool fibers and grafted on the fiber surface is obtained in this study, and the wool-nanoparticle composite material is found to have highly photocatalytic activities with an extremely narrow band gap of 2.8 eV. The wool fibers are obtained using three successive technical steps: wool fibers are swollen by using lithium bromide, then saturated with tetrabutyl titanate ethanol solution and subsequently treated in boiling water. It was demonstrated that the chemical bonds formed between the as-synthesized TiO2 nanoparticles and the wool fibers swollen by lithium bromide include C‑Ti4+(Ti3+), N‑Ti4+(Ti3+), O‑Ti3+, and S‑Ti4+(Ti3+) bonds. The modified wool fibers have shown markedly improved photocatalytic efficiency due to their enhanced visible light absorption capability, which is much better than the (N-doped) TiO2 coated wool fibers. In contrast, TiO2 modified wool fibers swollen by using formic acid have poorer photoactivity, this might be due to the elimination of trivalent titanium between TiO2 nanoparticles and the wool fibers.

Enhanced photocatalytic activity of wool fibers having titanium dioxide nanoparticles formed inside their cortex.

PubMed

Zhang, Hui; Sun, Runjun; Wu, Hailiang; Mao, Ningtao

2018-05-01

A wool-TiO2 nanoparticle composite material having TiO2 nanoparticles both infiltrated in the matrix between macrofibrils inside cortical cells of wool fibers and grafted on the fiber surface is obtained in this study, and the wool-nanoparticle composite material is found to have highly photocatalytic activities with an extremely narrow band gap of 2.8 eV. The wool fibers are obtained using three successive technical steps: wool fibers are swollen by using lithium bromide, then saturated with tetrabutyl titanate ethanol solution and subsequently treated in boiling water. It was demonstrated that the chemical bonds formed between the as-synthesized TiO2 nanoparticles and the wool fibers swollen by lithium bromide include C-Ti4+(Ti3+), N-Ti4+(Ti3+), O-Ti3+, and S-Ti4+(Ti3+) bonds. The modified wool fibers have shown markedly improved photocatalytic efficiency due to their enhanced visible light absorption capability, which is much better than the (N-doped) TiO2 coated wool fibers. In contrast, TiO2 modified wool fibers swollen by using formic acid have poorer photoactivity, this might be due to the elimination of trivalent titanium between TiO2 nanoparticles and the wool fibers. © 2018 IOP Publishing Ltd.

Wide spectral and wavelength-tunable dissipative soliton fiber laser with topological insulator nano-sheets self-assembly films sandwiched by PMMA polymer.

PubMed

Wang, Qingkai; Chen, Yu; Miao, Lili; Jiang, Guobao; Chen, Shuqing; Liu, Jun; Fu, Xiquan; Zhao, Chujun; Zhang, Han

2015-03-23

Topological insulators have been theoretically predicted as promising candidates for broadband photonics devices due to its large bulk band gap states in association with the spin-momentum-locked mass-less Dirac edge/surface states. Unlike the bulk counterpart, few-layer topological insulators possess some intrinsic optical advantages, such as low optical loss, low saturation intensity and high concentration of surface state. Herein, we use a solvothermal method to prepare few-layer Bi₂Te₃ flakes. By sandwiching few-layer Bi₂Te₃ flakes with polymethyl methacrylate (PMMA) polymer, a novel light modulation device had been successfully fabricated with high chemical and thermal stabilities as well as excellent mechanical durability, originating from the contribution of PMMA acting as buffer layers that counteract excessive mechanical bending within the fragile Bi₂Te₃ flakes. The incorporation of the as-fabricated PMMA-TI-PMMA as saturable absorber, which could bear long-term mechanical loadings, into the fiber laser cavity generated the stable dissipative soliton mode-locking with a 3-dB spectral bandwidth up to 51.62 nm and tunable wavelength range of 22 nm. Our work provides a new way of fabricating PMMA-TI-PMMA sandwiched composite structure as saturable absorber with promising applications for laser operation.

Black phosphorus quantum dots for femtosecond laser photonics

NASA Astrophysics Data System (ADS)

Liu, Meng; Jiang, Xiao-Fang; Yan, Yu-Rong; Wang, Xu-De; Luo, Ai-Ping; Xu, Wen-Cheng; Luo, Zhi-Chao

2018-01-01

As a rising two-dimensional (2D) nanomaterial, layered black phosphorus (BP) nanosheets have shown promising applications in electronics and photonics. Besides the 2D layered structure, recently black phosphorus quantum dots (BPQDs) exhibiting unique optoelectronic properties had been successfully fabricated. However, the nonlinear optical properties of BPQDs at the telecommunication band have not been investigated. Herein, we synthesized the BPQDs by using a liquid exfoliation method that combined probe sonication and bath sonication. It was found that the evident saturable absorption ability of BPQDs at 1.55 μm waveband could be clearly observed. As for the applications of ultrafast photonics, we fabricated the BPQDs saturable absorber (BPQDs-SA) and applied it to an ultrafast laser. By virtue of the excellent nonlinear optical properties of BPQDs, the fiber laser delivers the stable pulse train with duration as short as 291 fs, whose performance could, to the best of our knowledge, compete with nowadays' commercial optical saturable absorber devices. In addition, due to the highly nonlinear optical effect generated by the fabricated BPQDs-SA, the multi-soliton nonlinear dynamics in the fiber laser were also investigated. The obtained results suggest that the BPQDs could be an attractive nonlinear optical material for applications in the field of nonlinear optics.

Bi2Te3 based passively Q-switched at 1042.76 and 1047 nm wavelength

NASA Astrophysics Data System (ADS)

Salim, M. A. M.; Shaharuddin, R. A.; Ismail, M. A.; Harun, S. W.; Ahmad, H.; Azzuhri, Saaidal R.

2017-12-01

In this paper, we propose and demonstrate the generation of dual wavelength based photonic crystal fiber passively Q-switched using few-layer TI:Bi2Te3 (bismuth telluride) saturable absorbers in a 1 micron waveband. The system employs a few-layer bismuth, induced onto a fiber ferrule using a dry oven method. A centered dual-wavelength output at 1042.76 and 1047.0 nm was produced from the Ytterbium doped fiber laser setup by incorporating 10 cm of photonic crystal fiber and finely adjusting the polarization controller. The self-started Q-switch had a pump power of 132.15 mW and a frequency ranging from 3.79 to 15.63 kHz. Therefore, TI:Bi2Te3 was suitable as a potential broadband SA in a 1 micron region.

Fiber networks amplify active stress

PubMed Central

Ronceray, Pierre; Broedersz, Chase P.

2016-01-01

Large-scale force generation is essential for biological functions such as cell motility, embryonic development, and muscle contraction. In these processes, forces generated at the molecular level by motor proteins are transmitted by disordered fiber networks, resulting in large-scale active stresses. Although these fiber networks are well characterized macroscopically, this stress generation by microscopic active units is not well understood. Here we theoretically study force transmission in these networks. We find that collective fiber buckling in the vicinity of a local active unit results in a rectification of stress towards strongly amplified isotropic contraction. This stress amplification is reinforced by the networks’ disordered nature, but saturates for high densities of active units. Our predictions are quantitatively consistent with experiments on reconstituted tissues and actomyosin networks and shed light on the role of the network microstructure in shaping active stresses in cells and tissue. PMID:26921325

Chromium:forsterite laser frequency comb stabilization and development of portable frequency references inside a hollow optical fiber

NASA Astrophysics Data System (ADS)

Thapa, Rajesh

We have made significant accomplishments in the development of portable frequency standard inside hollow optical fibers. Such standards will improve portable optical frequency references available to the telecommunications industry. Our approach relies on the development of a stabilized Cr:forsterite laser to generate the frequency comb in the near-IR region. This laser is self referenced and locked to a CW laser which in turn is stabilized to a sub-Doppler feature of a molecular transition. The molecular transition is realized using a hollow core fiber filled with acetylene gas. We finally measured the absolute frequency of these molecular transitions to characterize the references. In this thesis, the major ideas, techniques and experimental results for the development and absolute frequency measurement of the portable frequency references are presented. A prism-based Cr:forsterite frequency comb is stabilized. We have effectively used the prism modulation along with power modulation inside the cavity in order to actively stabilize the frequency comb. We have also studied the carrier-envelope-offset frequency (f0) dynamics of the laser and its effect on laser stabilization. A reduction of f0 linewidth from ˜2 MHz to ˜20 kHz has also been observed. Both our in-loop and out-of-loop measurements of the comb stability showed that the comb is stable within a part in 1011 at 1-s gate time and is currently limited by our reference signal. In order to develop this portable frequency standard, saturated absorption spectroscopy is performed on the acetylene v1 + v3 band near 1532 nm inside different kinds of hollow optical fibers. The observed linewidths are a factor 2 narrower in the 20 mum fiber as compared to 10 mum fiber, and vary from 20-40 MHz depending on pressure and power. The 70 mum kagome fiber shows a further reduction in linewidth to less than 10 MHz. In order to seal the gas inside the hollow optical fiber, we have also developed a technique of splicing the hollow fiber to solid fiber in a standard commercial arc splicer, rather than the more expensive filament splicer, and achieved comparable splice loss. We locked a CW laser to the saturated absorption feature using a Frequency Modulation technique and then compared to an optical frequency comb. The stabilized frequency comb, providing a dense grid of reference frequencies in near-infrared region is used to characterize and measure the absolute frequency reference based on these hollow optical fibers.

Large-area tungsten disulfide for ultrafast photonics.

PubMed

Yan, Peiguang; Chen, Hao; Yin, Jinde; Xu, Zihan; Li, Jiarong; Jiang, Zike; Zhang, Wenfei; Wang, Jinzhang; Li, Irene Ling; Sun, Zhipei; Ruan, Shuangchen

2017-02-02

Two-dimensional (2D) layered transition metal dichalcogenides (TMDs) have attracted significant interest in various optoelectronic applications due to their excellent nonlinear optical properties. One of the most important applications of TMDs is to be employed as an extraordinary optical modulation material (e.g., the saturable absorber (SA)) in ultrafast photonics. The main challenge arises while embedding TMDs into fiber laser systems to generate ultrafast pulse trains and thus constraints their practical applications. Herein, few-layered WS 2 with a large-area was directly transferred on the facet of the pigtail and acted as a SA for erbium-doped fiber laser (EDFL) systems. In our study, WS 2 SA exhibited remarkable nonlinear optical properties (e.g., modulation depth of 15.1% and saturable intensity of 157.6 MW cm -2 ) and was used for ultrafast pulse generation. The soliton pulses with remarkable performances (e.g., ultrashort pulse duration of 1.49 ps, high stability of 71.8 dB, and large pulse average output power of 62.5 mW) could be obtained in a telecommunication band. To the best of our knowledge, the average output power of the mode-locked pulse trains is the highest by employing TMD materials in fiber laser systems. These results indicate that atomically large-area WS 2 could be used as excellent optical modulation materials in ultrafast photonics.

Dietary outcomes in a Spanish-language randomized controlled diabetes prevention trial with pregnant Latinas.

PubMed

Kieffer, Edith C; Welmerink, Diana B; Sinco, Brandy R; Welch, Kathleen B; Rees Clayton, Erin M; Schumann, Christina Y; Uhley, Virginia E

2014-03-01

We evaluated the effectiveness of a community-based healthy lifestyle intervention in improving dietary behaviors of pregnant Latinas from 2004 to 2006 in Detroit, Michigan. The 11-week, culturally tailored, Spanish-language Healthy Mothers on the Move (MOMs) intervention offered home visits, group classes, related activities, and social support from trained community health workers (CHWs) and peers. Dietary behaviors were measured by food frequency questionnaire. Linear mixed models estimated pre- and post-intervention changes, within and between MOMs intervention and minimal intervention (MI) groups. MOMs (n = 139) and MI (n = 139) participants had similar baseline characteristics and dietary intake. Post-intervention, MOMs participants showed significant improvement in all dietary behaviors, except fruit and fiber consumption. Compared with MI participants, MOMs participants had significantly decreased consumption of added sugar (P = .05), total fat (P < .05), saturated fat (P < .01), percentage of daily calories from saturated fat (P < .001), solid fats and added sugars (P < .001), and had increased vegetable consumption (P < .001). Their increase in fiber consumption (P < .05) was significant relative to MI participants' decrease in fiber intake. We confirmed the hypothesis that a community-planned, CHW-led healthy lifestyle intervention could improve dietary behaviors of low-income Latina women during pregnancy.

Simulation of dissipative-soliton-resonance generation in a passively mode-locked Yb-doped fiber laser

NASA Astrophysics Data System (ADS)

Du, Wenxiong; Li, Heping; Liu, Cong; Shen, Shengnan; Zhang, Shangjian; Liu, Yong

2017-10-01

We present a numerical investigation of dissipative-soliton-resonance (DSR) generation in an all-normal-dispersion Ybdoped fiber laser mode-locked by a real saturable absorber (SA). In the simulation model, the SA includes both the saturable absorption and excited-state absorption (ESA) effects. The intra-cavity pulse evolution is numerically simulated with different transmission functions of SA. When omitting the ESA effect, the transmissivity of SA increases monotonically with the input pulse power. The noise-like pulse (NLP) operation in the cavity is obtained at high pump power, which is attributed to the spectral filtering effect. When the ESA effect is activated, higher instantaneous power part of pulse encounters larger loss induced by SA, causing that the pulse peak power is clamped at a certain fixed value. With increasing pump, the pulse starts to extend in the time domain while the pulse spectrum is considerably narrowed. In this case, the NLP operation state induced by the spectral filtering effect is avoided and the DSR is generated. Our simulation results indicate that the ESA effect in the SA plays a dominant role in generating the DSR pulses, which will be conducive to comprehending the mechanism of DSR generation in passively mode-locked fiber lasers.

Frequency stabilization of a 1083 nm fiber laser to {sup 4}He transition lines with optical heterodyne saturation spectroscopies

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

Gong, W.; Peng, X., E-mail: xiangpeng@pku.edu.cn; Li, W.

2014-07-15

Two kinds of optical heterodyne saturation spectroscopies, namely, frequency modulation spectroscopy (FMS) and modulation transfer spectroscopy (MTS), are demonstrated for locking a fiber laser to the transition lines of metastable {sup 4}He atoms around 1083 nm. The servo-loop error signals of FMS and MTS for stabilizing laser frequency are optimized by studying the dependence of the peak-to-peak amplitude and slope on the optical power of pump and probe beams. A comparison of the stabilization performances of FMS/MTS and polarization spectroscopy (PS) is presented, which shows that MTS exhibits relatively superior performance with the least laser frequency fluctuation due to itsmore » flat-background dispersive signal, originated from the four-wave mixing process. The Allan deviation of the stabilized laser frequency is 5.4 × 10{sup −12}@100 s with MTS for data acquired in 1000 s, which is sufficiently applicable for fields like laser cooling, optical pumping, and optical magnetometry.« less

Creep of Sylramic-iBN Fiber Tows at Elevated Temperature in Air and in Silicic Acid-Saturated Steam

DTIC Science & Technology

2015-06-01

elements, R type control thermocouples and a 90-mm (3.5-in.) hot zone; reproduced from Armani [15] All tests employed an alumina susceptor (ceramic...Furnace Leff (500) = 39.9mm T = 500°C, Steam 45 4.1.2 Strain Measurement In this work tensile creep tests were performed using a dead-weight... strain and the strain rate of the specimen in the hot test section. These methods are briefly recapitulated here. Extension of the fiber tow

Concentration dependence and self-similarity of photodarkening losses induced in Yb-doped fibers by comparable excitation.

PubMed

Taccheo, Stefano; Gebavi, Hrvoje; Monteville, Achille; Le Goffic, Olivier; Landais, David; Mechin, David; Tregoat, Denis; Cadier, Benoit; Robin, Thierry; Milanese, Daniel; Durrant, Tim

2011-09-26

We report on an extensive investigation of photodarkening in Yb-doped silica fibers. A set of similar fibers, covering a large Yb concentration range, was made so as to compare the photodarkening induced losses. Careful measurements were made to ensure equal and uniform inversion for all the tested fibers. The results show that, with the specific set-up, the stretching parameter obtained through fitting has a very limited variation. This gives more meaning to the fitting parameters. Results tend to indicate a square law dependence of the concentration of excited ions on the final saturated loss. We also demonstrate self-similarity of loss evolution when experimental curves are simply normalized to fitting parameters. This evidence of self-similarity also supports the possibility of introducing a preliminary figure of merit for Yb-doped fiber. This will allow the impact of photodarkening on laser/amplifier devices to be evaluated. © 2011 Optical Society of America

Dissipative vector soliton in a dispersion-managed fiber laser with normal dispersion.

PubMed

Wang, Siming; Fan, Xuliang; Zhao, Luming; Wang, Yong; Tang, Dingyuan; Shen, Deyuan

2014-12-10

We numerically study the vector dynamics of dissipative solitons (DSs) in a 2 μm dispersion-managed fiber laser mode locked by a semiconductor saturable absorber mirror and operated in the normal dispersion regime. It is shown that the effective gain bandwidth is crucial for the DS generation. The steep spectral edges of DSs are the consequence of the interaction among the normal dispersion, fiber nonlinearity, gain and loss, and gain dispersion effect, etc. We numerically duplicate the experimental results and further explore the vector features of the generated DSs. Two DSs formed along the two orthogonal polarization directions which, incoherently coupled with each other, could propagate in the birefringent cavity with the same group velocity.

Nanotube mode locked, wavelength-tunable, conventional and dissipative solitons fiber laser

NASA Astrophysics Data System (ADS)

Yun, Ling; Zhao, Wei

2018-01-01

We report the generation of widely wavelength tunable conventional solitons (CSs) and dissipative solitons (DSs) in an erbium-doped fiber laser passively mode-locked by nanotube saturable absorber. The tuning ranges of CSs and DSs are ∼15 and ∼25 nm, respectively. In anomalous dispersion regime, the output CS exhibits symmetrical spectral sidebands with transform-limited pulse duration of ∼1.1 ps. In the contrastive case of normal dispersion regime, the DS has rectangular spectrum profile and large frequency chirp, which presents pulse duration of ∼13.5 ps, and can be compressed to ∼0.4 ps external to the cavity. This fiber laser can provide two distinct types of tunable soliton sources, which is attractive for practical applications in telecommunications.

Tungsten diselenide for mode-locked erbium-doped fiber lasers with short pulse duration

NASA Astrophysics Data System (ADS)

Liu, Wenjun; Liu, Mengli; OuYang, Yuyi; Hou, Huanran; Ma, Guoli; Lei, Ming; Wei, Zhiyi

2018-04-01

In this paper, a WSe2 film prepared by chemical vapor deposition (CVD) is transferred onto a tapered fiber, and a WSe2 saturable absorber (SA) is fabricated. In order to measure the third-order optical nonlinearity of the WSe2, the Z-scan technique is applied. The modulation depth of the WSe2 SA is measured as being 21.89%. Taking advantage of the remarkable nonlinear absorption characteristic of the WSe2 SA, a mode-locked erbium-doped fiber laser is demonstrated at 1557.4 nm with a bandwidth of 25.8 nm and signal to noise ratio of 96 dB. To the best of our knowledge, the pulse duration of 163.5 fs is confirmed to be the shortest compared with previous mode-locked fiber lasers based on transition-metal dichalcogenides SAs. These results indicate that WSe2 is a powerful competitor in the application of ultrashort pulse lasers.

Integration of single-fiber reflectance spectroscopy into ultrasound-guided endoscopic lung cancer staging of mediastinal lymph nodes

NASA Astrophysics Data System (ADS)

Kanick, Stephen Chad; van der Leest, Cor; Aerts, Joachim G. J. V.; Hoogsteden, Henk C.; Kaščáková, Slávka; Sterenborg, Henricus J. C. M.; Amelink, Arjen

2010-01-01

We describe the incorporation of a single-fiber reflectance spectroscopy probe into the endoscopic ultrasound fine-needle aspiration (EUS-FNA) procedure utilized for lung cancer staging. A mathematical model is developed to extract information about the physiological and morphological properties of lymph tissue from single-fiber reflectance spectra, e.g., microvascular saturation, blood volume fraction, bilirubin concentration, average vessel diameter, and Mie slope. Model analysis of data from a clinical pilot study shows that the single-fiber reflectance measurement is capable of detecting differences in the physiology between normal and metastatic lymph nodes. Moreover, the clinical data show that probe manipulation within the lymph node can perturb the in vivo environment, a concern that must be carefully considered when developing a sampling strategy. The data show the feasibility of this novel technique; however, the potential clinical utility has yet to be determined.

Etching of semiconductors and metals by the photonic jet with shaped optical fiber tips

NASA Astrophysics Data System (ADS)

Pierron, Robin; Lecler, Sylvain; Zelgowski, Julien; Pfeiffer, Pierre; Mermet, Frédéric; Fontaine, Joël

2017-10-01

The etching of semiconductors and metals by a photonic jet (PJ) generated with a shaped optical fiber tip is studied. Etched marks with a diameter of 1 μm have been realized on silicon, stainless steel and titanium with a 35 kHz pulsed laser, emitting 100 ns pulses at 1064 nm. The selection criteria of the fiber and its tip are discussed. We show that a 100/140 silica fiber is a good compromise which takes into account the injection, the working distance and the energy coupled in the higher-order modes. The energy balance is performed on the basis of the known ablation threshold of the material. Finally, the dependence between the etching depth and the number of pulses is studied. Saturation is observed probably due to a redeposition of the etched material, showing that a higher pulse energy is required for deeper etchings.

Three-dimensional modeling of CPA to the multimillijoule level in tapered Yb-doped fibers for coherent combining systems.

PubMed

Andrianov, Alexey; Anashkina, Elena; Kim, Arkady; Meyerov, Iosif; Lebedev, Sergey; Sergeev, Alexander; Mourou, Gerard

2014-11-17

We developed a three-dimensional numerical model of Large-Mode-Area chirped pulse fiber amplifiers which includes nonlinear beam propagation in nonuniform multimode waveguides as well as gain spectrum dynamics in quasi-three-level active ions. We used our model in tapered Yb-doped fiber amplifiers and showed that single-mode propagation is maintained along the taper even in the presence of strong Kerr nonlinearity and saturated gain, allowing extraction of up to 3 mJ of output energy in 1 ns pulse. Energy scaling and its limitation as well as the influence of fiber taper bending and core irregularities on the amplifier performance were studied. We also investigated numerically the capabilities for compression and coherent combining of up to 36 perturbed amplifying channels and showed more than 70% combining efficiency, even with up to 11% of high-order modes in individual channels.

Poly (N-vinyl Carbazole) - Polypyrrole/graphene oxide nanocomposite material on tapered fiber for Q-switched pulse generation

NASA Astrophysics Data System (ADS)

Ahmad, H.; Faruki, M. J.; Jasim, A. A.; Ooi, S. I.; Thambiratnam, K.

2018-02-01

A passively Q-switched fiber laser using a Saturable Absorber (SA) fabricated from a new Poly (N-vinyl Carbazole) - Polypyrrole/Graphene Oxide (PNVC-PPy/GO) nanocomposite material deposited on a tapered fiber is proposed and demonstrated. The PNVC-PPy/GO composition is deposited along a 3 mm length of the 6.5 cm tapered fiber which has a tapered waist of 8 μm. Q-switched pulses are obtained with repetition rates of 25.15-42.7 kHz and pulse widths of 5.74-2.48 μs over a pump power range of 12.8-40.0 mW. A maximum average power of 0.19 mW and pulse energy of 4.43 nJ are also observed. The proposed Q-switched maintains advantages of a simple design and low fabrication cost while at the same time generating high quality Q-switched pulses.

Natural Kenaf Fiber Reinforced Composites as Engineered Structural Materials

NASA Astrophysics Data System (ADS)

Dittenber, David B.

The objective of this work was to provide a comprehensive evaluation of natural fiber reinforced polymer (NFRP)'s ability to act as a structural material. As a chemical treatment, aligned kenaf fibers were treated with sodium hydroxide (alkalization) in different concentrations and durations and then manufactured into kenaf fiber / vinyl ester composite plates. Single fiber tensile properties and composite flexural properties, both in dry and saturated environments, were assessed. Based on ASTM standard testing, a comparison of flexural, tensile, compressive, and shear mechanical properties was also made between an untreated kenaf fiber reinforced composite, a chemically treated kenaf fiber reinforced composite, a glass fiber reinforced composite, and oriented strand board (OSB). The mechanical properties were evaluated for dry samples, samples immersed in water for 50 hours, and samples immersed in water until saturation (~2700 hours). Since NFRPs are more vulnerable to environmental effects than synthetic fiber composites, a series of weathering and environmental tests were conducted on the kenaf fiber composites. The environmental conditions studied include real-time outdoor weathering, elevated temperatures, immersion in different pH solutions, and UV exposure. In all of these tests, degradation was found to be more pronounced in the NFRPs than in the glass FRPs; however, in nearly every case the degradation was less than 50% of the flexural strength or stiffness. Using a method of overlapping and meshing discontinuous fiber ends, large mats of fiber bundles were manufactured into composite facesheets for structural insulated panels (SIPs). The polyisocyanurate foam cores proved to be poorly matched to the strength and stiffness of the NFRP facesheets, leading to premature core shear or delamination failures in both flexure and compressive testing. The NFRPs were found to match well with the theoretical stiffness prediction methods of classical lamination theory, finite element method, and Castigliano's method in unidirectional tension and compression, but are less accurate for the more bond-dependent flexural and shear properties. With the acknowledged NFRP matrix bonding issues, the over-prediction of these theoretical models indicates that the flexural stiffness of the kenaf composite may be increased by up to 40% if a better bond between the fiber and matrix can be obtained. The sustainability of NFRPs was examined from two perspectives: environmental and socioeconomic. While the kenaf fibers themselves possess excellent sustainability characteristics, costing less while possessing a lesser environmental impact than the glass fibers, the vinyl ester resin used in the composites is environmentally hazardous and inflated the cost and embodied energy of the composite SIPs. Consistent throughout all the designs was a correlation between the respective costs of the raw materials and the respective environmental impacts. The socioeconomic study looked at the sustainability of natural fiber reinforced composite materials as housing materials in developing countries. A literature study on the country of Bangladesh, where the fibers in this study were grown, showed that the jute and kenaf market would benefit from the introduction of a value-added product like natural fiber composites. The high rate of homeless and inadequately housed in Bangladesh, as well as in the US and throughout the rest of the world, could be somewhat alleviated if a new, affordable, and durable material were introduced. While this study found that natural fiber composites possess sufficient mechanical properties to be adopted as primary structural members, the two major remaining hurdles needing to be overcome before natural fiber composites can be adopted as housing materials are the cost and sustainability of the resin system and the moisture resistance/durability of the fibers. (Abstract shortened by UMI.)

Dietary fiber does not displace energy but is associated with decreased serum cholesterol concentrations in healthy children.

PubMed

Ruottinen, Soile; Lagström, Hanna K; Niinikoski, Harri; Rönnemaa, Tapani; Saarinen, Maiju; Pahkala, Katja A; Hakanen, Maarit; Viikari, Jorma Sa; Simell, Olli

2010-03-01

Dietary fiber has health benefits, but fiber recommendations for children are controversial because fiber may displace energy. The objective was to longitudinally evaluate dietary fiber intake in children and to study associations between growth variables, serum cholesterol concentrations, and intakes of fiber, energy, and nutrients. Altogether, 543 children from a prospective randomized atherosclerosis prevention trial (the Special Turku Coronary Risk factor Intervention Project; STRIP) participated in this study between the ages of 8 mo and 9 y. The intervention children (n = 264) were counseled to replace part of saturated fat with unsaturated fat. Nutrient intakes, weight, height, and serum total, HDL-, and LDL-cholesterol and triglyceride concentrations were analyzed. Children were divided into 3 groups according to mean dietary fiber intake in foods: low (lowest 10%), high (highest 10%), and average (middle 80%) fiber intakes. Fiber intake associated positively with energy intake and inversely with fat intake. Children with a high fiber intake received more vitamins and minerals than did children in other groups. In longitudinal growth analyses, weights and heights were similar in all 3 fiber intake groups, and fiber intake (g/d) associated positively with weight gain between 8 mo and 2 y. Serum cholesterol concentrations decreased with increasing fiber intakes. Children in the intervention group had a higher fiber intake than did the control children during the entire follow-up period. Fiber intake did not displace energy or disturb growth between 13 mo and 9 y of age. Serum cholesterol values correlated inversely with fiber intake, which indicated that part of the cholesterol-lowering intervention effect in the STRIP project may have been explained by dietary fiber.

Adolescent Compliance with Dietary Guidelines: Health and Education Implications.

ERIC Educational Resources Information Center

Read, Marsha H.; And Others

1988-01-01

Surveyed 389 adolescents regarding their compliance with six U. S. Dietary Guidelines. Results indicated highest compliance on "eat a variety of foods" and "eat foods with adequate starch and fiber." Lowest compliance on "reduce sugar intake" and "reduce fat, saturated fat, and cholesterol intake." Females reported lower compliance to "maintain…

Ceramic to metal attachment system. [Ceramic electrode to metal conductor in MHD generator

DOEpatents

Marchant, D.D.

1983-06-10

A composition and method are described for attaching a ceramic electrode to a metal conductor. A layer of randomly interlocked metal fibers saturated with polyimide resin is sandwiched between the ceramic electrode and the metal conductor. The polyimide resin is then polymerized providing bonding.

Drying and control of moisture content and dimensional changes

Treesearch

Richard Bergman

2010-01-01

The discussion in this chapter is concerned with moisture content determination, recommended moisture content values, drying methods, methods of calculating dimensional changes, design factors affecting such changes in structures, and moisture content control during transit, storage, and construction. Data on green moisture content, fiber saturation point, shrinkage,...

Optimizing the noise characteristics of high-power fiber laser systems

NASA Astrophysics Data System (ADS)

Jauregui, Cesar; Müller, Michael; Kienel, Marco; Emaury, Florian; Saraceno, Clara J.; Limpert, Jens; Keller, Ursula; Tünnermann, Andreas

2017-02-01

The noise characteristics of high-power fiber lasers, unlike those of other solid-state lasers such as thin-disks, have not been systematically studied up to now. However, novel applications for high-power fiber laser systems, such as attosecond pulse generation, put stringent limits to the maximum noise level of these sources. Therefore, in order to address these applications, a detailed knowledge and understanding of the characteristics of noise and its behavior in a fiber laser system is required. In this work we have carried out a systematic study of the propagation of the relative intensity noise (RIN) along the amplification chain of a state-of-the-art high-power fiber laser system. The most striking feature of these measurements is that the RIN level is progressively attenuated after each amplification stage. In order to understand this unexpected behavior, we have simulated the transfer function of the RIN in a fiber amplification stage ( 80μm core) as a function of the seed power and the frequency. Our simulation model shows that this damping of the amplitude noise is related to saturation. Additionally, we show, for the first time to the best of our knowledge, that the fiber design (e.g. core size, glass composition, doping geometry) can be modified to optimize the noise characteristics of high-power fiber laser systems.

Waveform agile high-power fiber laser illuminators for directed-energy weapon systems

NASA Astrophysics Data System (ADS)

Engin, Doruk; Lu, Wei; Kimpel, Frank; Gupta, Shantanu

2012-06-01

A kW-class fiber-amplifier based laser illuminator system at 1030nm is demonstrated. At 125 kHz pulse repetition rate, 1.9mJ energy per pulse (235W average power) is achieved for 100nsec pulses with >72% optical conversion efficiency, and at 250kHz repetition, >350W average power is demonstrated, limited by the available pumps. Excellent agreement is established between the experimental results and dynamic fiber amplifier simulation, for predicting the pulse shape, spectrum and ASE accumulation throughout the fiber-amplifier chain. High pulse-energy, high power fiber-amplifier operation requires careful engineering - minimize ASE content throughout the pre-amplifier stages, use of large mode area gain fiber in the final power stage for effective pulse energy extraction, and pulse pre-shaping to compensate for the laser gain-saturation induced intra-pulse and pulse-pattern dependent distortion. Such optimization using commercially available (VLMA) fibers with core size in the 30-40μm range is estimated to lead to >4mJ pulse energy for 100nsec pulse at 50kHz repetition rate. Such waveform agile high-power, high-energy pulsed fiber laser illuminators at λ=1030nm satisfies requirements for active-tracking/ranging in high-energy laser (HEL) weapon systems, and in uplink laser beacon for deep space communication.

Water-soluble dietary fibers and cardiovascular disease.

PubMed

Theuwissen, Elke; Mensink, Ronald P

2008-05-23

One well-established way to reduce the risk of developing cardiovascular disease (CVD) is to lower serum LDL cholesterol levels by reducing saturated fat intake. However, the importance of other dietary approaches, such as increasing the intake of water-soluble dietary fibers is increasingly recognized. Well-controlled intervention studies have now shown that four major water-soluble fiber types-beta-glucan, psyllium, pectin and guar gum-effectively lower serum LDL cholesterol concentrations, without affecting HDL cholesterol or triacylglycerol concentrations. It is estimated that for each additional gram of water-soluble fiber in the diet serum total and LDL cholesterol concentrations decrease by -0.028 mmol/L and -0.029 mmol/L, respectively. Despite large differences in molecular structure, no major differences existed between the different types of water-soluble fiber, suggesting a common underlying mechanism. In this respect, it is most likely that water-soluble fibers lower the (re)absorption of in particular bile acids. As a result hepatic conversion of cholesterol into bile acids increases, which will ultimately lead to increased LDL uptake by the liver. Additionally, epidemiological studies suggest that a diet high in water-soluble fiber is inversely associated with the risk of CVD. These findings underlie current dietary recommendations to increase water-soluble fiber intake.

Black phosphorus saturable absorber for ultrashort pulse generation

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

Sotor, J., E-mail: jaroslaw.sotor@pwr.edu.pl; Sobon, G.; Abramski, K. M.

Low-dimensional materials, due to their unique and versatile properties, are very interesting for numerous applications in electronics and optoelectronics. Recently rediscovered black phosphorus, with a graphite-like layered structure, can be effectively exfoliated up to the single atomic layer called phosphorene. Contrary to graphene, it possesses a direct band gap controllable by the number of stacked atomic layers. For those reasons, black phosphorus is now intensively investigated and can complement or replace graphene in various photonics and electronics applications. Here, we demonstrate that black phosphorus can serve as a broadband saturable absorber and can be used for ultrashort optical pulse generation.more » The mechanically exfoliated ∼300 nm thick layers of black phosphorus were transferred onto the fiber core, and under pulsed excitation at 1560 nm wavelength, its transmission increases by 4.6%. We have demonstrated that the saturable absorption of black phosphorus is polarization sensitive. The fabricated device was used to mode-lock an Er-doped fiber laser. The generated optical solitons with the 10.2 nm bandwidth and 272 fs duration were centered at 1550 nm. The obtained results unambiguously show that black phosphorus can be effectively used for ultrashort pulse generation with performances similar or even better than currently used graphene or carbon nanotubes. This application of black phosphorus proves its great potential to future practical use in photonics.« less

All-optical noise reduction of fiber laser via intracavity SOA structure.

PubMed

Ying, Kang; Chen, Dijun; Pan, Zhengqing; Zhang, Xi; Cai, Haiwen; Qu, Ronghui

2016-10-10

We have designed a unique intracavity semiconductor optical amplifier (SOA) structure to suppress the relative intensity noise (RIN) for a fiber DFB laser. By exploiting the gain saturation effect of the SOA, a maximum noise suppression of 30 dB around the relaxation oscillation frequency is achieved, and the whole resonance relaxation oscillation peak completely disappears. Moreover, via a specially designed intracavity SOA structure, the optical intensity inside the SOA will be in a balanced state via the oscillation in the laser cavity, and the frequency noise of the laser will not be degraded with the SOA.

Saturated evanescent-wave absorption of few-layer graphene-covered side-polished single-mode fiber for all-optical switching

NASA Astrophysics Data System (ADS)

Peng, Kaung-Jay; Wu, Chun-Lung; Lin, Yung-Hsiang; Wang, Hwai-Yung; Cheng, Chih-Hsien; Chi, Yu-Chieh; Lin, Gong-Ru

2018-01-01

Using the evanescent-wave saturation effect of hydrogen-free low-temperature synthesized few-layer graphene covered on the cladding region of a side-polished single-mode fiber, a blue pump/infrared probe-based all-optical switch is demonstrated with specific wavelength-dependent probe modulation efficiency. Under the illumination of a blue laser diode at 405 nm, the few-layer graphene exhibits cross-gain modulation at different wavelengths covering the C- and L-bands. At a probe power of 0.5 mW, the L-band switching throughput power variant of 16 μW results in a probe modulation depth of 3.2%. Blue shifting the probe wavelength from 1580 to 1520 nm further enlarges the switching throughput power variant to 24 mW and enhances the probe modulation depth to 5%. Enlarging the probe power from 0.5 to 1 mW further enlarges the switching throughput power variant from 25 to 58 μW to promote its probe modulation depth of up to 5.8% at 1520 nm. In contrast, the probe modulation depth degrades from 5.1% to 1.2% as the pumping power reduces from 85 to 24 mW, which is attributed to the saturable absorption of the few-layer graphene-based evanescent-wave absorber. The modulation depth at wavelength of 1550 nm under a probe power of 1 mW increases from 1.2% to 5.1%, as more carriers can be excited when increasing the blue laser power from 24 to 85 mW, whereas it decreases from 5.1% to 3.3% by increasing the input probe power from 1 to 2 mW to show an easier saturated condition at longer wavelength.

Water use, canopy temperature, lint yield, and fiber quality response of six upland cotton cultivars to water stress

USDA-ARS?s Scientific Manuscript database

The declining saturated thickness of the Ogallala Aquifer combined with the unpredictability of precipitation during the growing season in the Southern High Plains has resulted in elevated production risks associated with short-term crop water deficits. Cotton (Gossypium spp.) cultivars that can use...

Consensus dietary guidelines for healthy living and prevention of obesity, the metabolic syndrome, diabetes, and related disorders in Asian Indians.

PubMed

Misra, Anoop; Sharma, Rekha; Gulati, Seema; Joshi, Shashank R; Sharma, Vinita; Ghafoorunissa; Ibrahim, Ahamed; Joshi, Shilpa; Laxmaiah, Avula; Kurpad, Anura; Raj, Rebecca K; Mohan, Viswanathan; Chandalia, Hemraj; Krishnaswamy, Kamala; Boindala, Sesikeran; Gopalan, Sarath; Bhattiprolu, Siva Kumar; Modi, Sonal; Vikram, Naval K; Makkar, Brij Mohan; Mathur, Manju; Dey, Sanjit; Vasudevan, Sudha; Gupta, Shashi Prabha; Puri, Seema; Joshi, Prashant; Khanna, Kumud; Mathur, Prashant; Krishnaswamy, Sheela; Madan, Jagmeet; Karmarkar, Madhukar; Seth, Veenu; Passi, Santosh Jain; Chadha, Davinder; Bhardwaj, Swati

2011-06-01

India is undergoing rapid nutritional transition, resulting in excess consumption of calories, saturated fats, trans fatty acids, simple sugars, salt and low intake of fiber. Such dietary transition and a sedentary lifestyle have led to an increase in obesity and diet-related non-communicable diseases (type 2 diabetes mellitus [T2DM], cardiovascular disease [CVD], etc.) predominantly in urban, but also in rural areas. In comparison with the previous guidelines, these consensus dietary guidelines include reduction in the intake of carbohydrates, preferential intake of complex carbohydrates and low glycemic index foods, higher intake of fiber, lower intake of saturated fats, optimal ratio of essential fatty acids, reduction in trans fatty acids, slightly higher protein intake, lower intake of salt, and restricted intake of sugar. While these guidelines are applicable to Asian Indians in any geographical setting, they are particularly applicable to those residing in urban and in semi-urban areas. Proper application of these guidelines will help curb the rising "epidemics" of obesity, the metabolic syndrome, hypertension, T2DM, and CVD in Asian Indians.

Large-area and highly crystalline MoSe2 for optical modulator

NASA Astrophysics Data System (ADS)

Yin, Jinde; Chen, Hao; Lu, Wei; Liu, Mengli; Li, Irene Ling; Zhang, Min; Zhang, Wenfei; Wang, Jinzhang; Xu, Zihan; Yan, Peiguang; Liu, Wenjun; Ruan, Shuangchen

2017-12-01

Transition metal dichalcogenides (TMDs) have been successfully used as broadband optical modulator materials for pulsed fiber laser systems. However, the nonlinear optical absorptions of exfoliated TMDs are strongly limited by their nanoflakes morphology with uncontrollable lateral size and thickness. In this work, we provide an effective method to fully explore the nonlinear optical properties of MoSe2. Large-area and high quality lattice MoSe2 grown by chemical vapor deposition method was adopted as an optical modulator for the first time. The large-area MoSe2 shows excellent nonlinear optical absorption with a large modulation depth of 21.7% and small saturable intensity of 9.4 MW cm-2. After incorporating the MoSe2 optical modulator into fiber laser cavity as a saturable absorber, a highly stable Q-switching operation with single pulse energy of 224 nJ is achieved. The large-area MoSe2 possessing superior nonlinear optical properties compared to exfoliated nanoflakes affords possibility for the larger-area two-dimensional materials family as high performance optical devices.

Noise-like pulse generation in an ytterbium-doped fiber laser using tungsten disulphide

NASA Astrophysics Data System (ADS)

Zhang, Wenping; Song, Yanrong; Guoyu, Heyang; Xu, Runqin; Dong, Zikai; Li, Kexuan; Tian, Jinrong; Gong, Shuang

2017-12-01

We demonstrated the noise-like pulse (NLP) generation in an ytterbium-doped fiber (YDF) laser with tungsten disulphide (WS2). Stable fundamental mode locking and second-order harmonic mode locking were observed. The saturable absorber (SA) was a WS2-polyvinyl alcohol film. The modulation depth of the WS2 film was 2.4%, and the saturable optical intensity was 155 MW cm-2. Based on this SA, the fundamental NLP with a pulse width of 20 ns and repetition rate of 7 MHz were observed. The autocorrelation trace of output pulses had a coherent spike, which came from NLP. The average pulse width of the spike was 550 fs on the top of a broad pedestal. The second-order harmonic NLP had a spectral bandwidth of 1.3 nm and pulse width of 10 ns. With the pump power of 400 mW, the maximum output power was 22.2 mW. To the best of our knowledge, this is the first time a noise-like mode locking in an YDF laser based on WS2-SA in an all normal dispersion regime was obtained.

Lightning Current Measurement with Fiber-Optic Sensor

NASA Technical Reports Server (NTRS)

Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George N.; Mata, Carlos T.; Mata, Angel G.; Snyder, Gary P.

2014-01-01

A fiber-optic current sensor is successfully developed with many potential applications for electric current measurement. Originally developed for in-flight lightning measurement, the sensor utilizes Faraday Effect in an optical fiber. The Faraday Effect causes linear light polarization in a fiber to rotate when the fiber is exposed to a magnetic field. The polarization change is detected using a reflective polarimetric scheme. Forming fiber loops and applying Ampere's law, measuring the total light rotation results in the determination of the total current enclosed. The sensor is conformable to complex structure geometry. It is also non-conductive and immune to electromagnetic interference, saturation or hysteresis. Installation is non-intrusive, and the sensor can be safely routed through flammable areas. Two similar sensor systems are described in this paper. The first system operates at 1310nm laser wavelength and is capable of measuring approximately 300 A - 300 kA, a 60 dB range. Laboratory validation results of aircraft lighting direct and in-direct effect current amplitudes are reported for this sensor. The second system operates at 1550nm wavelength and can measure about 400 A - 400 kA. Triggered-lightning measurement data are presented for this system. Good results are achieved in all cases.

A switchable and stable single-longitudinal-mode, dual-wavelength erbium-doped fiber laser assisted by Rayleigh backscattering in tapered fiber

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

Gu, Jian; Yang, Yanfu, E-mail: yangyanfu@hotmail.com; Zhang, Jianyu

We have proposed and demonstrated a novel switchable single-longitudinal-mode (SLM), dual-wavelength erbium-doped fiber laser (DWEDFL) assisted by Rayleigh backscattering (RBS) in a tapered fiber in a ring laser configuration. The RBS feedback in a tapered fiber is a key mechanism as linewidth narrowing for laser output. A compound laser cavity ensured that the EDFL operated in the SLM state and a saturable absorber (SA) is employed to form a gain grating for both filtering and improving wavelength stability. The fiber laser can output dual wavelengths simultaneously or operate at single wavelength in a switchable manner. Experiment results show that withmore » the proper SA, the peak power drift was improved from 1–2 dB to 0.31 dB and the optical signal to noise ratio was higher than 60 dB. Under the assistance of RBS feedback, the laser linewidths are compressed by around three times and the Lorentzian 3 dB linewidths of 445 Hz and 425 Hz are obtained at 1550 nm and 1554 nm, respectively.« less

Theoretical study of the effect of pump wavelength drift on mode instability in a high-power fiber amplifier

NASA Astrophysics Data System (ADS)

Liu, Yakun; Tao, Rumao; Su, Rongtao; Wang, Xiaolin; Ma, Pengfei; Zhang, Hanwei; Zhou, Pu; Si, Lei

2018-04-01

This paper presents an investigation of the effect of pump wavelength drift on the threshold of mode instability (MI) in high-power ytterbium-doped fiber lasers. By using a semi-analytical model, we study the effects of pump wavelength drift with a central pump wavelength around 976 nm and 915 nm, respectively. The influences of the pump absorption coefficient and total pump absorption are considered simultaneously. The results indicate that the effect of pump wavelength drift around 976 nm is stronger than that around 915 nm. For more efficient suppression of MI by shifting the pump wavelength, efficient absorption of pump power is required. The MI thresholds for fibers with different total pump absorptions and cladding diameters are compared. When the total pump absorption is increased, the gain saturation is enhanced, which results in the MI being mitigated more effectively and being more sensitive to pump wavelength drift. The MI threshold in gain fibers with larger inner cladding diameter is higher but more dependent upon pump wavelength. The results of this work can help in optimizing the pump wavelength and fiber parameters and suppressing MI in high-power fiber lasers.

Carbon nanotube-based mode-locked wavelength-switchable fiber laser via net gain cross section alteration

NASA Astrophysics Data System (ADS)

Latif, A. A.; Mohamad, H.; Abu Bakar, M. H.; Muhammad, F. D.; Mahdi, M. A.

2016-02-01

We have proposed and demonstrated a carbon nanotube-based mode-locked erbium-doped fiber laser with switchable wavelength in the C-band wavelength region by varying the net gain cross section of erbium. The carbon nanotube is coated on a tapered fiber to form the saturable absorber for the purpose of mode-locking by exploiting the concept of evanescent field interaction on the tapered fiber with the carbon nanotube in a ring cavity configuration. The propagation loss is adjusted by inducing macrobend losses of the optical fiber in the cavity through a fiber spooling technique. Since the spooling radius can be gradually adjusted to achieve continuous tuning of attenuation, this passive tuning approach can be an alternative to optical tunable attenuator, with freedom of external device integration into the laser cavity. Based on this alteration, the net gain cross section of the laser system can be tailored to three different lasing wavelength ranges; 1533, 1560 nm and both (1533 and 1560 nm) with the minimum pulse duration of 734 fs. The proposed design is simple and stable with high beam quality and good reliability for multiple applications.

Mechanical and physical properties of carbon-graphite fiber-reinforced polymers intended for implant suprastructures.

PubMed

Segerström, Susanna; Ruyter, I Eystein

2007-09-01

Mechanical properties and quality of fiber/matrix adhesion of poly(methyl methacrylate) (PMMA)-based materials, reinforced with carbon-graphite (CG) fibers that are able to remain in a plastic state until polymerization, were examined. Tubes of cleaned braided CG fibers were treated with a sizing resin. Two resin mixtures, resin A and resin B, stable in the fluid state and containing different cross-linking agents, were reinforced with CG fiber loadings of 24, 36, and 47 wt% (20, 29, and 38 vol.%). In addition, resin B was reinforced with 58 wt% (47 vol.%). After heat-polymerization, flexural strength and modulus were evaluated, both dry and after water storage. Coefficient of thermal expansion, longitudinally and in the transverse direction of the specimens, was determined. Adhesion between fibers and matrix was evaluated with scanning electron microscopy (SEM). Flexural properties and linear coefficient of thermal expansion were similar for both fiber composites. With increased fiber loading, flexural properties increased. For 47 wt% fibers in polymer A the flexural strength was 547.7 (28.12) MPa and for polymer B 563.3 (89.24) MPa when water saturated. Linear coefficient of thermal expansion was for 47 wt% CG fiber-reinforced polymers; -2.5 x 10(-6) degrees C-1 longitudinally and 62.4 x 10(-6) degrees C-1 in the transverse direction of the specimens. SEM revealed good adhesion between fibers and matrix. More porosity was observed with fiber loading of 58 wt%. The fiber treatment and the developed resin matrices resulted in good adhesion between CG fibers and matrix. The properties observed indicate a potential for implant-retained prostheses.

Robust, low-noise, polarization-maintaining mode-locked Er-fiber laser with a planar lightwave circuit (PLC) device as a multi-functional element.

PubMed

Kim, Chur; Kwon, Dohyeon; Kim, Dohyun; Choi, Sun Young; Cha, Sang Jun; Choi, Ki Sun; Yeom, Dong-Il; Rotermund, Fabian; Kim, Jungwon

2017-04-15

We demonstrate a new planar lightwave circuit (PLC)-based device, integrated with a 980/1550 wavelength division multiplexer, an evanescent-field-interaction-based saturable absorber, and an output tap coupler, which can be employed as a multi-functional element in mode-locked fiber lasers. Using this multi-functional PLC device, we demonstrate a simple, robust, low-noise, and polarization-maintaining mode-locked Er-fiber laser. The measured full-width at half-maximum bandwidth is 6 nm centered at 1555 nm, corresponding to 217 fs transform-limited pulse duration. The measured RIN and timing jitter are 0.22% [10 Hz-10 MHz] and 6.6 fs [10 kHz-1 MHz], respectively. Our results show that the non-gain section of mode-locked fiber lasers can be easily implemented as a single PLC chip that can be manufactured by a wafer-scale fabrication process. The use of PLC processes in mode-locked lasers has the potential for higher manufacturability of low-cost and robust fiber and waveguide lasers.

Gain dynamics of clad-pumped Yb-fiber amplifier and intensity noise control.

PubMed

Zhao, Jian; Guiraud, Germain; Floissat, Florian; Gouhier, Benoit; Rota-Rodrigo, Sergio; Traynor, Nicholas; Santarelli, Giorgio

2017-01-09

Gain dynamics study provides an attractive method to understand the intensity noise behavior in fiber amplifiers. Here, the gain dynamics of a medium power (5 W) clad-pumped Yb-fiber amplifier is experimentally evaluated by measuring the frequency domain transfer functions for the input seed and pump lasers from 10 Hz to 1 MHz. We study gain dynamic behavior of the fiber amplifier in the presence of significant residual pump power (compared to the seed power), showing that the seed transfer function is strongly saturated at low Fourier frequencies while the pump power modulation transfer function is nearly unaffected. The characterization of relative intensity noise (RIN) of the fiber amplifier is well explained by the gain dynamics analysis. Finally, a 600 kHz bandwidth feedback loop using an acoustic-optical modulator (AOM) controlling the seed intensity is successfully demonstrated to suppress the broadband laser intensity noise. A maximum noise reduction of about 30 dB is achieved leading to a RIN of -152 dBc/Hz (~1 kHz-10 MHz) at 2.5 W output power.

All-fiber radially/azimuthally polarized lasers based on mode coupling of tapered fibers.

PubMed

Mao, Dong; He, Zhiwen; Lu, Hua; Li, Mingkun; Zhang, Wending; Cui, Xiaoqi; Jiang, Biqiang; Zhao, Jianlin

2018-04-01

We demonstrate a mode converter with an insertion loss of 0.36 dB based on mode coupling of tapered single-mode and two-mode fibers, and realize all-fiber flexible cylindrical vector lasers at 1550 nm. Attributing to the continuous distribution of a tangential electric field at taper boundaries, the laser is switchable between the radially and azimuthally polarized states by adjusting the input polarization. In the temporal domain, the operation is controllable among continuous-wave, Q-switched, and mode-locked statuses by changing the saturable absorber or pump strength. The duration of Q-switched radially/azimuthally polarized laser spans from 10.4/10.8 to 6/6.4 μs at the pump range of 38 to 58 mW, while that of the mode-locked pulse varies from 39.2/31.9 to 5.6/5.2 ps by controlling the laser bandwidth. The proposed laser combines the features of a cylindrical vector beam, a fiber laser, and an ultrafast pulse, providing a special and cost-effective source for practical applications.

A novel Multi-Fiber Optode sensor system (MuFO) for monitoring oxygen

NASA Astrophysics Data System (ADS)

Koop-Jakobsen, K.; Fischer, J.; Wenzhöfer, F.

2012-04-01

In the marine environment, dissolved oxygen concentrations often vary significantly spatially as well as temporally. Monitoring these variations is essential for our understanding of the biological and chemical processes controlling the oxygen dynamics in water columns and sediments. Such investigations require a high number of measuring points and a high temporal resolution. A Multi-Fiber Optode sensor system (MuFO) was designed to assess these requirements. The MuFO system simultaneously controls 100 fiber optodes enabling continuous monitoring of oxygen in 100 positions within a 5-10m radius. The measurements are based on quenching of an oxygen sensitive luminophore, which is immobilised at the end of each fiber optode. The optical oxygen measurements are based on lifetime-imaging, which are converted into oxygen concentrations using a multipoint calibration. At a constant temperature of 21C, the system overall had a mean accuracy of 1.3%, a precision of 0.2% air saturation, the average 90% response time was 16 seconds and the detection limit was 0.1% air saturation. The MuFO set-up was build into a waterproof titanium casing for marine field applications. The system is battery-powered and has a maximum operational capacity of 15 hours for continuous measurements. The MuFO system was recently used for various research tasks in the marine environment: Mounted on a lander, the in situ MuFO system was used for investigations of oxygen dynamics in marine water columns placing the fiber optodes in a vertical line on a 7m high pole. For studies of oxygen dynamics in marine wetland rhizospheres, the sensing ends of the fiber optodes were covered with a 50cm protective sleeve made from stainless steel tubing, and the sensors were manually pushed into the rhizosphere. For laboratory measurements of sediment oxygen demand, the MuFO system was used to simultaneously monitor the oxygen consumption in multiple sediment slurry incubations. The MuFO system proved to be a useful tool for field studies as well as in the laboratory and the system has multiple applications in marine research. This work was supported by the 7th framework EU-projects SENSEnet and HYPOX.

Using graphene nano-particle embedded in photonic crystal fiber for evanescent wave mode-locking of fiber laser.

PubMed

Lin, Yung-Hsiang; Yang, Chun-Yu; Liou, Jia-Hong; Yu, Chin-Ping; Lin, Gong-Ru

2013-07-15

A photonic crystal fiber (PCF) with high-quality graphene nano-particles uniformly dispersed in the hole cladding are demonstrated to passively mode-lock the erbium-doped fiber laser (EDFL) by evanescent-wave interaction. The few-layer graphene nano-particles are obtained by a stabilized electrochemical exfoliation at a threshold bias. These slowly and softly exfoliated graphene nano-particle exhibits an intense 2D band and an almost disappeared D band in the Raman scattering spectrum. The saturable phenomena of the extinction coefficient β in the cladding provides a loss modulation for the intracavity photon intensity by the evanescent-wave interaction. The evanescent-wave mode-locking scheme effectively enlarges the interaction length of saturable absorption with graphene nano-particle to provide an increasing transmittance ΔT of 5% and modulation depth of 13%. By comparing the core-wave and evanescent-wave mode-locking under the same linear transmittance, the transmittance of the graphene nano-particles on the end-face of SMF only enlarges from 0.54 to 0.578 with ΔT = 3.8% and the modulation depth of 10.8%. The evanescent wave interaction is found to be better than the traditional approach which confines the graphene nano-particles at the interface of two SMF patchcords. When enlarging the intra-cavity gain by simultaneously increasing the pumping current of 980-nm and 1480-nm pumping laser diodes (LDs) to 900 mA, the passively mode-locked EDFL shortens its pulsewidth to 650 fs and broadens its spectral linewidth to 3.92 nm. An extremely low carrier amplitude jitter (CAJ) of 1.2-1.6% is observed to confirm the stable EDFL pulse-train with the cladding graphene nano-particle based evanescent-wave mode-locking.

Impact of the Bienestar School-Based Diabetes Mellitus Prevention Program on Fasting Capillary Glucose Levels

PubMed Central

Treviño, Roberto P.; Yin, Zenong; Hernandez, Arthur; Hale, Daniel E.; Garcia, Oralia A.; Mobley, Connie

2005-01-01

Objective To evaluate the impact of a school-based diabetes mellitus prevention program on low-income fourth-grade Mexican American children. Design A randomized controlled trial with 13 intervention and 14 control schools. Setting Elementary schools in inner-city neighborhoods in San Antonio, Tex. Participants Eighty percent of participants were Mexican American and 94% were from economically disadvantaged households. Baseline and follow-up measures were collected from 1419 (713 intervention and 706 control) and 1221 (619 intervention and 602 control) fourth-grade children, respectively. Intervention The Bienestar Health Program consists of a health class and physical education curriculum, a family program, a school cafeteria program, and an after-school health club. The objectives are to decrease dietary saturated fat intake, increase dietary fiber intake, and increase physical activity. Main Outcome Measures The primary end point was fasting capillary glucose level, and the secondary end points were percentage of body fat, physical fitness level, dietary fiber intake, and dietary saturated fat intake. Fasting capillary glucose level, bioelectric impedance, modified Harvard step test, three 24-hour dietary recalls, weight, and height were collected at baseline and 8 months later. Results Children in the intervention arm attended an average of 32 Bienestar sessions. Mean fasting capillary glucose levels decreased in intervention schools and increased in control schools after adjusting for covariates (−2.24 mg/dL [0.12 mmol/L]; 95% confidence interval, −6.53 to 2.05 [−0.36 to 0.11 mmol/L]; P = .03). Fitness scores (P = .04) and dietary fiber intake (P = .009) significantly increased in intervention children and decreased in control children. Percentage of body fat (P = .56) and dietary saturated fat intake (P = .52) did not differ significantly between intervention and control children. Conclusion This intervention showed some positive results, but additional research is needed to examine long-term benefits, translation, and cost-effectiveness. PMID:15351759

Room temperature single photon source using fiber-integrated hexagonal boron nitride

NASA Astrophysics Data System (ADS)

Vogl, Tobias; Lu, Yuerui; Lam, Ping Koy

2017-07-01

Single photons are a key resource for quantum optics and optical quantum information processing. The integration of scalable room temperature quantum emitters into photonic circuits remains to be a technical challenge. Here we utilize a defect center in hexagonal boron nitride (hBN) attached by Van der Waals force onto a multimode fiber as a single photon source. We perform an optical characterization of the source in terms of spectrum, state lifetime, power saturation and photostability. A special feature of our source is that it allows for easy switching between fiber-coupled and free space single photon generation modes. In order to prove the quantum nature of the emission we measure the second-order correlation function {{g}(2)}≤ft(τ \\right) . For both fiber-coupled and free space emission, the {{g}(2)}≤ft(τ \\right) dips below 0.5 indicating operation in the single photon regime. The results so far demonstrate the feasibility of 2D material single photon sources for scalable photonic quantum information processing.

Real-time color image processing for forensic fiber investigations

NASA Astrophysics Data System (ADS)

Paulsson, Nils

1995-09-01

This paper describes a system for automatic fiber debris detection based on color identification. The properties of the system are fast analysis and high selectivity, a necessity when analyzing forensic fiber samples. An ordinary investigation separates the material into well above 100,000 video images to analyze. The system is based on standard techniques such as CCD-camera, motorized sample table, and IBM-compatible PC/AT with add-on-boards for video frame digitalization and stepping motor control as the main parts. It is possible to operate the instrument at full video rate (25 image/s) with aid of the HSI-color system (hue- saturation-intensity) and software optimization. High selectivity is achieved by separating the analysis into several steps. The first step is fast direct color identification of objects in the analyzed video images and the second step analyzes detected objects with a more complex and time consuming stage of the investigation to identify single fiber fragments for subsequent analysis with more selective techniques.

Hybrid mode-locked erbium-doped all-fiber soliton laser with a distributed polarizer.

PubMed

Chernykh, D S; Krylov, A A; Levchenko, A E; Grebenyukov, V V; Arutunyan, N R; Pozharov, A S; Obraztsova, E D; Dianov, E M

2014-10-10

A soliton-type erbium-doped all-fiber ring laser hybrid mode-locked with a co-action of arc-discharge single-walled carbon nanotubes (SWCNTs) and nonlinear polarization evolution (NPE) is demonstrated. For the first time, to the best of our knowledge, boron nitride-doped SWCNTs were used as a saturable absorber for passive mode-locking initiation. Moreover, the NPE was introduced through the implementation of the short-segment polarizing fiber. Owing to the NPE action in the laser cavity, significant pulse length shortening as well as pulse stability improvement were observed as compared with a SWCNTs-only mode-locked laser. The shortest achieved pulse width of near transform-limited solitons was 222 fs at the output average power of 9.1 mW and 45.5 MHz repetition frequency, corresponding to the 0.17 nJ pulse energy.

Hydraulic characterization of " Furcraea andina

NASA Astrophysics Data System (ADS)

Rivera-Velasquez, M. F.; Fallico, C.; Molinari, A.; Santillan, P.; Salazar, M.

2012-04-01

The present level of pollution, increasingly involving groundwaters, constitutes a serious risk for environment and human health. Therefore the remediation of saturated and unsaturated soils, removing pollutant materials through innovative and economic bio-remediation techniques is more frequently required. Recent studies on natural fiber development have shown the effectiveness of these fibers for removal of some heavy metals, due to the lignin content in the natural fibers which plays an important role in the adsorption of metal cations (Lee et al., 2004; Troisi et al., 2008; C. Fallico, 2010). In the context of remediation techniques for unsaturated and/or saturated zone, an experimental approach for the hydraulic characterization of the "Furcraea andina" (i.e., Cabuya Blanca) fiber was carried out. This fiber is native to Andean regions and grows easily in wild or cultivated form in the valleys and hillsides of Colombia, Ecuador, and Peru. Fibers of "Furcraea andina" were characterized by experimental tests to determine their hydraulic conductivity or permeability and porosity in order to use this medium for bioremediation of contaminated aquifer exploiting the physical, chemical and microbial capacity of natural fiber in heavy metal adsorption. To evaluate empirically the hydraulic conductivity, laboratory tests were carried out at constant head specifically on the fibers manually extracted. For these tests we used a flow cell (used as permeameter), containing the "Furcraea andina" fibers to be characterized, suitably connected by a tygon pipe to a Marriott's bottle, which had a plastic tube that allow the adjustment of the hydraulic head for different tests to a constant value. By this experiment it was also possible to identify relationships that enable the estimation of permeability as a function of density, i.e. of the compaction degree of the fibers. Our study was carried out for three values of hydraulic head (H), namely 10, 18, and 25 cm and for each constant head we repeated the test for three different rate of fiber compaction within the flow cell, corresponding to three different densities (146 kg/m3, 200 kg/m3 and 240 kg/m3). We observed that with increasing density of the fibers there is an increase of hydraulic conductivity. The importance of the experimental results on permeability acquires greater relevance when compared to the values of hydraulic conductivity already known from the literature for different soils types. In this study, special attention has been given to the value of hydraulic conductivity of this fiber, considering that in the framework of groundwater remediation strategies if the hydraulic conductivity in the barrier is lower than that of the surrounding aquifer, the plume may change its natural pathway, bypassing the barrier and veering towards larger hydraulic conductivity. Reference • Lee, B. G. and Rowell, R. M.: Removal of heavy metal ions from aqueous solutions using lignocellulosic fibers, J. Natural Fibers, 1, 97-108, 2004. • Troisi, S., Fallico, C., Straface, S., and Mazzuca, L.: Biodreni per la bonifica di siti contaminati realizzati con fibre naturali liberiane ad elevato sviluppo superficiale. Brevetto dell'Università della Calabria (n.: CS2008A00018), 2008. • C. Fallico, S. Troisi, A. Molinari, and M. F. Rivera.: Characterization of broom fibers for PRB in the remediation of aquifers contaminated by heavy metals, Biogeosciences journal , 7, 2545-2556, 2010

Broad band nonlinear optical absorption measurements of the laser dye IR26 using white light continuum Z-scan

NASA Astrophysics Data System (ADS)

Dey, Soumyodeep; Bongu, Sudhakara Reddy; Bisht, Prem Ballabh

2017-03-01

We study the nonlinear optical response of a standard dye IR26 using the Z-scan technique, but with the white light continuum. The continuum source of wavelength from 450 nm to 1650 nm has been generated from the photonic crystal fiber on pumping with 772 nm of Ti:Sapphire oscillator. The use of broadband incident pulse enables us to probe saturable absorption (SA) and reverse saturable absorption (RSA) over the large spectral range with a single Z-scan measurement. The system shows SA in the resonant region while it turns to RSA in the non-resonant regions. The low saturation intensity of the dye can be explained based on the simultaneous excitation from ground states to various higher energy levels with the help of composite energy level diagram. The cumulative effects of excited state absorption and thermal induced nonlinear optical effects are responsible for the observed RSA.

Radially polarized and passively Q-switched Yb-doped fiber laser based on intracavity birefringent mode discrimination

NASA Astrophysics Data System (ADS)

Sun, Xuehuan; Wu, Yongxiao; Chen, Sanbin; Li, Jianlang

2018-05-01

In this paper, we demonstrated a passive Q-switched ytterbium-doped fiber laser with radially polarized beam emission by using a c-cut YVO4 birefringent crystal as the intracavity polarization discriminator, and a Cr4+:YAG crystal as the saturable absorber and output coupler. The maximum averaged laser power reached 3.89 W with a high slope efficiency of 66.5%. The laser pulse had a peak power of 161 W, 160 ns duration, and 151 kHz repetition rate at the absorbed pump power of 6.48 W. Such a radially polarized pulse would facilitate numerous applications.

Wavelength and pulse duration tunable ultrafast fiber laser mode-locked with carbon nanotubes.

PubMed

Li, Diao; Jussila, Henri; Wang, Yadong; Hu, Guohua; Albrow-Owen, Tom; C T Howe, Richard; Ren, Zhaoyu; Bai, Jintao; Hasan, Tawfique; Sun, Zhipei

2018-02-09

Ultrafast lasers with tunable parameters in wavelength and time domains are the choice of light source for various applications such as spectroscopy and communication. Here, we report a wavelength and pulse-duration tunable mode-locked Erbium doped fiber laser with single wall carbon nanotube-based saturable absorber. An intra-cavity tunable filter is employed to continuously tune the output wavelength for 34 nm (from 1525 nm to 1559 nm) and pulse duration from 545 fs to 6.1 ps, respectively. Our results provide a novel light source for various applications requiring variable wavelength or pulse duration.

Exploration of Single-Chip Phase-Sensitive Amplifiers

DTIC Science & Technology

2015-11-05

dispersion result of an ITU G.653 single mode fiber. The input wavelength was shifted from 1545 nm to 1575 nm. As we can see from Fig. 14, at 1550 nm...saturate the SOA, the measurement can only covers a wavelength range from 1545 nm to 1575 nm because of the limited gain bandwidth of the EDFA we

Annealing texture of nanostructured IF steel

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

Jamaati, Roohollah, E-mail: jamaati@nit.ac.ir

In the present work, the evolution of annealing texture in nanostructured interstitial free steel fabricated via accumulative roll bonding (ARB) process was investigated. Textural evolution after post-annealing of ARB-processed samples was evaluated using X-ray diffraction. There were several texture transitions in the γ-fiber and ζ-fiber during ARB and post-annealing treatment. It was found that with increasing the number of ARB cycles, the volume fraction of the low angle grain boundary decreased and the high angle grain boundary fraction increased. Also, the shear texture was dominant after the first cycle, while for other samples, the rolling texture was dominant. The one-cyclemore » sample clearly indicated a weak α-fiber and γ-fiber and a relatively strong ζ-fiber. In addition, during the recrystallization and before the grain growth, the intensity of α-fiber and γ-fiber decreased, the intensity of ζ-fiber increased, and the intensity of (011)〈100〉 orientation in the ε-fiber and η-fiber increased. Moreover, it was concluded that the transition from the rolling texture to the shear one was a sign of occurrence of the recrystallization (before the grain growth). Finally, with increasing the number of ARB cycles, the intensity of rolling and shear textures saturated and a stable texture formed. - Highlights: • There were texture transitions in the γ-fiber and ζ-fiber. • When the number of cycles increased, the low angle grain boundaries decreased. • The shear texture was dominant after the first cycle. • Transition from rolling texture to shear one was a sign of recrystallization. • With increasing the number of ARB cycles, a stable texture formed.« less

Q-switched erbium doped fiber laser based on single and multiple walled carbon nanotubes embedded in polyethylene oxide film as saturable absorber

NASA Astrophysics Data System (ADS)

Ahmed, M. H. M.; Ali, N. M.; Salleh, Z. S.; Rahman, A. A.; Harun, S. W.; Manaf, M.; Arof, H.

2015-01-01

A passive, stable and low cost Q-switched Erbium-doped fiber laser (EDFL) is demonstrated using both single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs), which are embedded in polyethylene oxide (PEO) film as a saturable absorber (SA). The film is sandwiched between two FC/PC fiber connectors and integrated into the laser cavity for Q-switching pulse generation operating at wavelength of 1533.6 nm. With SWCNTs, the laser produces a stable pulse train with repetition rate and pulse width ranging from 9.52 to 33.33 kHz and 16.8 to 8.0 μs while varying the 980 nm pump power from 48.5 mW to 100.4 mW. On the other hand, with MWCNTs, the repetition rate and pulse width can be tuned in a wider range of 6.12-33.62 kHz and 9.5- 4.2 μs, respectively as the pump power increases from 37.9 to 120.6 mW. The MWCNTs produce the pulse train at a lower threshold and attain a higher repetition rate compared to the SWCNTs. This is due to thicker carbon nanotubes layer of the MWCNTs which provides more absorption and consequently higher damage threshold. The Q-switched EDFL produces the highest pulse energy of 531 nJ at pump power of 37.9 mW with the use of MWCNTs-PEO SA.

Adsorption Properties of Lignin-derived Activated Carbon Fibers (LACF)

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

Contescu, Cristian I.; Gallego, Nidia C.; Thibaud-Erkey, Catherine

The object of this CRADA project between Oak Ridge National Laboratory (ORNL) and United Technologies Research Center (UTRC) is the characterization of lignin-derived activated carbon fibers (LACF) and determination of their adsorption properties for volatile organic compounds (VOC). Carbon fibers from lignin raw materials were manufactured at Oak Ridge National Laboratory (ORNL) using the technology previously developed at ORNL. These fibers were physically activated at ORNL using various activation conditions, and their surface area and pore-size distribution were characterized by gas adsorption. Based on these properties, ORNL did down-select five differently activated LACF materials that were delivered to UTRC formore » measurement of VOC adsorption properties. UTRC used standard techniques based on breakthrough curves to measure and determine the adsorption properties of indoor air pollutants (IAP) - namely formaldehyde and carbon dioxide - and to verify the extent of saturated fiber regenerability by thermal treatments. The results are summarized as follows: (1) ORNL demonstrated that physical activation of lignin-derived carbon fibers can be tailored to obtain LACF with surface areas and pore size distributions matching the properties of activated carbon fibers obtained from more expensive, fossil-fuel precursors; (2) UTRC investigated the LACF potential for use in air cleaning applications currently pursued by UTRC, such as building ventilation, and demonstrated their regenerability for CO2 and formaldehyde, (3) Both partners agree that LACF have potential for possible use in air cleaning applications.« less

A constitutive law for continuous fiber reinforced brittle matrix composites with fiber fragmentation and stress recovery

NASA Astrophysics Data System (ADS)

Neumeister, Jonas M.

1993-08-01

THE TENSILE BEHAVIOR of a brittle matrix composite is studied for post matrix crack saturation conditions. Scatter of fiber strength following the Weibull distribution as well as the influence of the major microstructural variables is considered. The stress in a fiber is assumed to recover linearly around a failure due to a fiber-matrix interface behavior mainly ruled by friction. The constitutive behavior for such a composite is analysed. Results are given for a simplified and a refined approximate description and compared with an analysis resulting from the exact analytical theory of fiber fragmentation. It is shown that the stress-strain relation for the refined model excellently follows the exact solution and gives the location of the maximum to within 1% in both stress and strain; for most materials the agreement is even better. Also it is shown that all relations can be normalized to depend on only two variables; a stress reference and the Weibull exponent. For systems with low scatter in fiber strength the simplified model is sufficient to determine the stress maximum but not the postcritical behavior. In addition, the simplified model gives explicit analytical expressions for the maximum stress and corresponding strain. None of the models contain any volume dependence or statistical scatter, but the maximum stress given by the stress-strain relation constitutes an upper bound for the ultimate tensile strength of the composite.

Impact of dietary fiber intake on glycemic control, cardiovascular risk factors and chronic kidney disease in Japanese patients with type 2 diabetes mellitus: the Fukuoka Diabetes Registry

PubMed Central

2013-01-01

Background Dietary fiber is beneficial for the treatment of type 2 diabetes mellitus, although it is consumed differently in ethnic foods around the world. We investigated the association between dietary fiber intake and obesity, glycemic control, cardiovascular risk factors and chronic kidney disease in Japanese type 2 diabetic patients. Methods A total of 4,399 patients were assessed for dietary fiber intake using a brief self-administered diet history questionnaire. The associations between dietary fiber intake and various cardiovascular risk factors were investigated cross-sectionally. Results Body mass index, fasting plasma glucose, HbA1c, triglyceride and high-sensitivity C-reactive protein negatively associated with dietary fiber intake after adjusting for age, sex, duration of diabetes, current smoking, current drinking, total energy intake, fat intake, saturated fatty acid intake, leisure-time physical activity and use of oral hypoglycemic agents or insulin. The homeostasis model assessment insulin sensitivity and HDL cholesterol positively associated with dietary fiber intake. Dietary fiber intake was associated with reduced prevalence of abdominal obesity, hypertension and metabolic syndrome after multivariate adjustments including obesity. Furthermore, dietary fiber intake was associated with lower prevalence of albuminuria, low estimated glomerular filtration rate and chronic kidney disease after multivariate adjustments including protein intake. Additional adjustments for obesity, hypertension or metabolic syndrome did not change these associations. Conclusion We demonstrated that increased dietary fiber intake was associated with better glycemic control and more favorable cardiovascular disease risk factors including chronic kidney disease in Japanese type 2 diabetic patients. Diabetic patients should be encouraged to consume more dietary fiber in daily life. PMID:24330576

NONLINEAR AND FIBER OPTICS: Influence of the Stark effect on the nature of stimulated Raman scattering of ultrashort adiabatic pump radiation

NASA Astrophysics Data System (ADS)

Kryzhanovskiĭ, B. V.

1990-04-01

An investigation is made of the serious limitations on the growth of the amplitude of a Stokes wave associated with the optical Stark effect and with the dispersion of the group velocities of the interacting pulses. It is shown that when the distance traversed exceeds a certain length, the gain due to stimulated Raman scattering reaches saturation whereas the spectrum of the scattered light becomes broader and acquires a line structure. Saturation of the scattering is not manifested at pump intensities sufficient to bleach the scattering medium. The gain can be optimized by altering the offset from a resonance.

60-GHz Millimeter-wave Over Fiber with Directly Modulated Dual-mode Laser Diode

PubMed Central

Tsai, Cheng-Ting; Lin, Chi-Hsiang; Lin, Chun-Ting; Chi, Yu-Chieh; Lin, Gong-Ru

2016-01-01

A directly modulated dual-mode laser diode (DMLD) with third-order intermodulation distortion (IMD3) suppression is proposed for a 60-GHz millimeter-wave over fiber (MMWoF) architecture, enabling new fiber-wireless communication access to cover 4-km single-mode-fiber (SMF) and 3-m wireless 16-QAM OFDM transmissions. By dual-mode injection-locking, the throughput degradation of the DMLD is mitigated with saturation effect to reduce its threshold, IMD3 power and relative intensity noise to 7.7 mA, −85 dBm and −110.4 dBc/Hz, respectively, providing huge spurious-free dynamic range of 85.8 dB/Hz2/3. This operation suppresses the noise floor of the DMLD carried QPSK-OFDM spectrum by 5 dB. The optical receiving power is optimized to restrict the power fading effect for improving the bit error rate to 1.9 × 10−3 and the receiving power penalty to 1.1 dB. Such DMLD based hybrid architecture for 60-GHz MMW fiber-wireless access can directly cover the current optical and wireless networks for next-generation indoor and short-reach mobile communications. PMID:27297267

Fiber-Optic Current Sensor Validation with Triggered Lightning Measurements

NASA Technical Reports Server (NTRS)

Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George N.; Mata, Carlos T.; Mata, Angel G.; Snyder, Gary P.

2013-01-01

A fiber optic current sensor based on the Faraday Effect is developed that is highly suitable for aircraft installation and can measure total current enclosed in a fiber loop down to DC. Other attributes include being small, light-weight, non-conducting, safe from electromagnetic interference, and free of hysteresis and saturation. The Faraday Effect causes light polarization to rotate when exposed to a magnetic field in the direction of light propagation. Measuring the induced light polarization rotation in fiber loops yields the total current enclosed. Two sensor systems were constructed and installed at Camp Blanding, Florida, measuring rocket-triggered lightning. The systems were similar in design but with different laser wavelengths, sensitivities and ranges. Results are compared to a shunt resistor as reference. The 850nm wavelength system tested in summer 2011 showed good result comparison early. However, later results showed gradual amplitude increase with time, attributed to corroded connections affecting the 50-ohm output termination. The 1550nm system also yielded good results in the summer 2012. The successful measurements demonstrate the fiber optic sensor's accuracies in capturing real lightning currents, and represent an important step toward future aircraft installation.

Fiber-Optic Sensor for Aircraft Lightning Current Measurement

NASA Technical Reports Server (NTRS)

Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George G.; Mata, Carlos T.; Mata,Angel G.; Snyder, Gary P.

2012-01-01

An electric current sensor based on Faraday rotation effect in optical fiber was developed for measuring aircraft lightning current. Compared to traditional sensors, the design has many advantages including the ability to measure total current and to conform to structure geometries. The sensor is also small, light weight, non-conducting, safe from interference, and free of hysteresis and saturation. Potential applications include characterization of lightning current waveforms, parameters and paths, and providing environmental data for aircraft certifications. In an optical fiber as the sensing medium, light polarization rotates when exposed to a magnetic field in the direction of light propagation. By forming closed fiber loops around a conductor and applying Ampere s law, measuring the total light rotation yields the enclosed current. A reflective polarimetric scheme is used, where polarization change is measured after the polarized light travels round-trip through the sensing fiber. The sensor system was evaluated measuring rocket-triggered lightning over the 2011 summer. Early results compared very well against a reference current shunt resistor, demonstrating the sensor's accuracy and feasibility in a lightning environment. While later comparisons show gradually increasing amplitude deviations for an undetermined cause, the overall waveforms still compared very well.

Body-monitoring and health supervision by means of optical fiber-based sensing systems in medical textiles.

PubMed

Quandt, Brit M; Scherer, Lukas J; Boesel, Luciano F; Wolf, Martin; Bona, Gian-Luca; Rossi, René M

2015-02-18

Long-term monitoring with optical fibers has moved into the focus of attention due to the applicability for medical measurements. Within this Review, setups of flexible, unobtrusive body-monitoring systems based on optical fibers and the respective measured vital parameters are in focus. Optical principles are discussed as well as the interaction of light with tissue. Optical fiber-based sensors that are already used in first trials are primarily selected for the section on possible applications. These medical textiles include the supervision of respiration, cardiac output, blood pressure, blood flow and its saturation with hemoglobin as well as oxygen, pressure, shear stress, mobility, gait, temperature, and electrolyte balance. The implementation of these sensor concepts prompts the development of wearable smart textiles. Thus, current sensing techniques and possibilities within photonic textiles are reviewed leading to multiparameter designs. Evaluation of these designs should show the great potential of optical fibers for the introduction into textiles especially due to the benefit of immunity to electromagnetic radiation. Still, further improvement of the signal-to-noise ratio is often necessary to develop a commercial monitoring system. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fiber-Optic Sensor for Aircraft Lightning Current Measurement

NASA Technical Reports Server (NTRS)

Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George G.; Mata, Carlos T.; Mata, Angel G.; Snyder, Gary P.

2012-01-01

An electric current sensor based on Faraday rotation effect in optical fiber was developed for measuring aircraft lightning current. Compared to traditional sensors, the design has many advantages including the ability to measure total current and to conform to structure geometries. The sensor is also small, light weight, non-conducting, safe from interference, and free of hysteresis and saturation. Potential applications include characterization of lightning current waveforms, parameters and paths, and providing environmental data for aircraft certifications. In an optical fiber as the sensing medium, light polarization rotates when exposed to a magnetic field in the direction of light propagation. By forming closed fiber loops around a conductor and applying Ampere s law, measuring the total light rotation yields the enclosed current. A reflective polarimetric scheme is used, where polarization change is measured after the polarized light travels round-trip through the sensing fiber. The sensor system was evaluated measuring rocket-triggered lightning over the 2011 summer. Early results compared very well against a reference current shunt resistor, demonstrating the sensor s accuracy and feasibility in a lightning environment. While later comparisons show gradually increasing amplitude deviations for an undetermined cause, the overall waveforms still compared very well.

Generation regimes of bidirectional hybridly mode-locked ultrashort pulse erbium-doped all-fiber ring laser with a distributed polarizer.

PubMed

Krylov, Alexander A; Chernykh, Dmitriy S; Arutyunyan, Natalia R; Grebenyukov, Vyacheslav V; Pozharov, Anatoly S; Obraztsova, Elena D

2016-05-20

We report on the stable picosecond and femtosecond pulse generation from the bidirectional erbium-doped all-fiber ring laser hybridly mode-locked with a coaction of a single-walled carbon nanotube-based saturable absorber and nonlinear polarization evolution that was introduced through the insertion of the short-segment polarizing fiber. Depending on the total intracavity dispersion value, the laser emits conservative solitons, transform-limited Gaussian pulses, or highly chirped stretched pulses with almost 20 nm wide parabolic spectrum in both clockwise (CW) and counterclockwise (CCW) directions of the ring. Owing to the polarizing action in the cavity, we have demonstrated for the first time, to the best of our knowledge, an efficient tuning of soliton pulse characteristics for both CW and CCW channels via an appropriate polarization control. We believe that the bidirectional laser presented may be highly promising for gyroscopic and other dual-channel applications.

Triggered generation of single guided photons from a single atom in a nanofiber cavity

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

Le Kien, Fam; Hakuta, K.

2011-04-15

We study the deterministic generation of single guided-mode photons from an atom in the vicinity of a nanofiber with two fiber-Bragg-grating (FBG) mirrors. The technique is based on a cavity-enhanced Raman scattering process involving an adiabatic passage. We take into account the scattering of the pump field from the fiber, the multilevel structure of the atom, and the surface-induced van der Waals potential in describing the photon generation process. We find that, due to the confinement of the cavity field in the transverse plane of the fiber and in the space between the FBG mirrors, the probability of the generationmore » of a single guided-mode photon can be close to unity even when the finesse of the nanofiber cavity is moderate. We show the possibilities of saturation and power broadening in the behavior of the number of photons emitted into the nanofiber.« less

A simple numerical model for membrane oxygenation of an artificial lung machine

NASA Astrophysics Data System (ADS)

Subraveti, Sai Nikhil; Sai, P. S. T.; Viswanathan Pillai, Vinod Kumar; Patnaik, B. S. V.

2015-11-01

Optimal design of membrane oxygenators will have far reaching ramification in the development of artificial heart-lung systems. In the present CFD study, we simulate the gas exchange between the venous blood and air that passes through the hollow fiber membranes on a benchmark device. The gas exchange between the tube side fluid and the shell side venous liquid is modeled by solving mass, momentum conservation equations. The fiber bundle was modelled as a porous block with a bundle porosity of 0.6. The resistance offered by the fiber bundle was estimated by the standard Ergun correlation. The present numerical simulations are validated against available benchmark data. The effect of bundle porosity, bundle size, Reynolds number, non-Newtonian constitutive relation, upstream velocity distribution etc. on the pressure drop, oxygen saturation levels etc. are investigated. To emulate the features of gas transfer past the alveoli, the effect of pulsatility on the membrane oxygenation is also investigated.

Highly precise stabilization of intracavity prism-based Er:fiber frequency comb using optical-microwave phase detector.

PubMed

Zhang, Shuangyou; Wu, Jiutao; Leng, Jianxiao; Lai, Shunnan; Zhao, Jianye

2014-11-15

In this Letter, we demonstrate a fully stabilized Er:fiber frequency comb by using a fiber-based, high-precision optical-microwave phase detector. To achieve high-precision and long-term phase locking of the repetition rate to a microwave reference, frequency control techniques (tuning pump power and cavity length) are combined together as its feedback. Since the pump power has been used for stabilization of the repetition rate, we introduce a pair of intracavity prisms as a regulator for carrier-envelope offset frequency, thereby phase locking one mode of the comb to the rubidium saturated absorption transition line. The stabilized comb performs the same high stability as the reference for the repetition rate and provides a residual frequency instability of 3.6×10(-13) for each comb mode. The demonstrated stabilization scheme could provide a high-precision comb for optical communication, direct frequency comb spectroscopy.

Time-domain NMR study of the drying of hemicellulose extracted aspen (Populus tremuloides Michx.)

Treesearch

Thomas Elder; Carl Houtman

2013-01-01

The effect of hot water on aspen chips has been evaluated using time-domain low-field nuclear magnetic resonance (NMR) spectroscopy. At moisture contents above fiber saturation point, treated chips exhibit relaxation times of free water longer than for the control. This is consistent with the removal of hemicelluloses given the hydrophilicity of these polysaccharides....

Moisture in untreated, a cetylated, and furfurylated Norway spruce studied during drying using time domain NMR

Treesearch

Lisabeth G. Thygesen; Thomas Elder

2008-01-01

Using time domain NMR, the moisture in Norway spruce (Picea abies (L.) Karst.) sapwood subjected to four different treatments (never-dried, dried and remoistened, acetylated, and furfurylated) was studied during drying at 40°C, at sample average moisture contents above fiber saturation. Spin-spin relaxation time distributions were derived from CPMG...

21 CFR 101.77 - Health claims: fruits, vegetables, and grain products that contain fiber, particularly soluble...

Code of Federal Regulations, 2013 CFR

2013-04-01

... complex carbohydrate content of these foods, other nutrients in these foods, or displacement of saturated... shall be declared in the nutrition information panel, consistent with § 101.9(c)(6)(i)(A). (d) Optional... “cholesterol.” (5) The claim may indicate that it is consistent with “Nutrition and Your Health: Dietary...

21 CFR 101.77 - Health claims: fruits, vegetables, and grain products that contain fiber, particularly soluble...

Code of Federal Regulations, 2011 CFR

2011-04-01

... complex carbohydrate content of these foods, other nutrients in these foods, or displacement of saturated... shall be declared in the nutrition information panel, consistent with § 101.9(c)(6)(i)(A). (d) Optional... “cholesterol.” (5) The claim may indicate that it is consistent with “Nutrition and Your Health: Dietary...

21 CFR 101.77 - Health claims: fruits, vegetables, and grain products that contain fiber, particularly soluble...

Code of Federal Regulations, 2012 CFR

2012-04-01

... complex carbohydrate content of these foods, other nutrients in these foods, or displacement of saturated... shall be declared in the nutrition information panel, consistent with § 101.9(c)(6)(i)(A). (d) Optional... “cholesterol.” (5) The claim may indicate that it is consistent with “Nutrition and Your Health: Dietary...

21 CFR 101.77 - Health claims: fruits, vegetables, and grain products that contain fiber, particularly soluble...

Code of Federal Regulations, 2014 CFR

2014-04-01

... complex carbohydrate content of these foods, other nutrients in these foods, or displacement of saturated... shall be declared in the nutrition information panel, consistent with § 101.9(c)(6)(i)(A). (d) Optional... “cholesterol.” (5) The claim may indicate that it is consistent with “Nutrition and Your Health: Dietary...

Threshold for ion movements in wood cell walls below fiber saturation observed by X-ray fluorescence microscopy (XFM)

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

Zelinka, Samuel L.; Gleber, Sophie-Charlotte; Vogt, Stefan

Diffusion of chemicals and ions through the wood cell wall plays an important role in wood damage mechanisms. In the present work, free diffusion of ions through wood secondary walls and middle lamellae has been investigated as a function of moisture content (MC) and anatomical direction. Various ions (K, Cl, Zn, Cu) were injected into selected regions of 2 mu m thick wood sections with a microinjector and then the ion distribution was mapped by means of X-ray fluorescence microscopy with submicron spatial resolution. The MC of the wood was controlled in situ by means of climatic chamber with controlledmore » relative humidity (RH). For all ions investigated, there was a threshold RH below which the concentration profiles did not change. The threshold RH depended upon ionic species, cell wall layer, and wood anatomical orientation. Above the threshold RH, differences in mobility among ions were observed and the mobility depended upon anatomical direction and cell wall layer. These observations support a recently proposed percolation model of electrical conduction in wood. The results contribute to understanding the mechanisms of fungal decay and fastener corrosion that occur below the fiber saturation point.« less

Dissolution-and-reduction CVD synthesis of few-layer graphene on ultra-thin nickel film lifted off for mode-locking fiber lasers

PubMed Central

Peng, Kaung-Jay; Lin, Yung-Hsiang; Wu, Chung-Lun; Lin, Sheng-Fong; Yang, Chun-Yu; Lin, Shih-Meng; Tsai, Din-Ping; Lin, Gong-Ru

2015-01-01

The in-situ dissolution-and-reduction CVD synthesized few-layer graphene on ultra-thin nickel catalyst film is demonstrated at temperature as low as 550 °C, which can be employed to form transmission-type or reflection-type saturable absorber (SA) for mode-locking the erbium-doped fiber lasers (EDFLs). With transmission-type graphene SA, the EDFL shortens its pulsewidth from 483 to 441 fs and broadens its spectral linewidth from 4.2 to 6.1 nm with enlarging the pumping current from 200 to 900 mA. In contrast, the reflection-type SA only compresses the pulsewidth from 875 to 796 fs with corresponding spectral linewidth broadened from 2.2 to 3.3 nm. The reflection-type graphene mode-locker increases twice of its equivalent layer number to cause more insertion loss than the transmission-type one. Nevertheless, the reflection-type based saturable absorber system can generate stabilized soliton-like pulse easier than that of transmission-type system, because the nonlinearity induced self-amplitude modulation depth is simultaneously enlarged when passing through the graphene twice under the retro-reflector design. PMID:26328535

The Comparison of Dietary Behaviors among Rural Controlled and Uncontrolled Hypertensive Patients.

PubMed

Kamran, Aziz; Shekarchi, Ali Akbar; Sharifian, Elham; Heydari, Heshmatolah

2016-01-01

Nutrition is a dominant peripheral factor in increasing blood pressure; however, little information is available about the nutritional status of hypertensive patients in Iran. This study aimed to compare nutritional behaviors of the rural controlled and uncontrolled hypertensive patients and to determine the predictive power of nutritional behaviors from blood pressure. This cross-sectional study was conducted on 671 rural hypertensive patients, using multistage random sampling method in Ardabil city in 2013. Data were collected by a 3-day food record questionnaire. Nutritional data were extracted by Nutritionist 4 software and analyzed by the SPSS 18 software using Pearson correlation, multiple linear regression, ANOVA, and independent t-test. A significant difference was observed in the means of fat intake, cholesterol, saturated fat, sodium, energy, calcium, vitamin C, fiber, and nutritional knowledge between controlled and uncontrolled groups. In the controlled group, sodium, saturated fats, vitamin C, calcium, and energy intake explained 30.6% of the variations in blood pressure and, in the uncontrolled group, sodium, carbohydrate, fiber intake, and nutritional knowledge explained 83% of the variations in blood pressure. There was a significant difference in the nutritional behavior between the two groups and changes in blood pressure could be explained significantly by nutritional behaviors.

Deterministic chaos in an ytterbium-doped mode-locked fiber laser

NASA Astrophysics Data System (ADS)

Mélo, Lucas B. A.; Palacios, Guillermo F. R.; Carelli, Pedro V.; Acioli, Lúcio H.; Rios Leite, José R.; de Miranda, Marcio H. G.

2018-05-01

We experimentally study the nonlinear dynamics of a femtosecond ytterbium doped mode-locked fiber laser. With the laser operating in the pulsed regime a route to chaos is presented, starting from stable mode-locking, period two, period four, chaos and period three regimes. Return maps and bifurcation diagrams were extracted from time series for each regime. The analysis of the time series with the laser operating in the quasi mode-locked regime presents deterministic chaos described by an unidimensional Rossler map. A positive Lyapunov exponent $\\lambda = 0.14$ confirms the deterministic chaos of the system. We suggest an explanation about the observed map by relating gain saturation and intra-cavity loss.

Passively mode-locking induced by gold nanorods in erbium-doped fiber lasers

NASA Astrophysics Data System (ADS)

Kang, Zhe; Xu, Yang; Zhang, Lei; Jia, Zhixu; Liu, Lai; Zhao, Dan; Feng, Yan; Qin, Guanshi; Qin, Weiping

2013-07-01

We demonstrated a passively mode-locked erbium-doped fiber laser by using gold nanorods as a saturable absorber. The gold nanorods (GNRs) were mixed with sodium carboxymethylcellulose (NaCMC) to form GNRs-NaCMC films. By inserting one of the GNRs-NaCMC films into an EDFL cavity pumped by a 980 nm laser diode, stable passively mode-locking was achieved with a threshold pump power of ˜54 mW, and 12 ps pulses at 1561 nm with a repetition rate of 34.7 MHz and a maximum average power of ˜2.05 mW were obtained for a pump power of ˜62 mW.

Health advantages and disadvantages of weight-reducing diets: a computer analysis and critical review.

PubMed

Anderson, J W; Konz, E C; Jenkins, D J

2000-10-01

Some weight-loss diets are nutritionally sound and consistent with recommendations for healthy eating while others are "fad" diets encouraging irrational and, sometimes, unsafe practices. The purpose of the study was to compare several weight loss diets and assess their potential long-term effects. Eight popular weight-loss diets were selected (Atkins, Protein Power, Sugar Busters, Zone, ADA Exchange, High-Fiber Fitness, Pritikin and Omish) to be non-clinically analyzed by means of a computer to predict their relative benefits/potential harm. A summary description, menu plan and recommended snacks were developed for each diet. The nutrient composition of each diet was determined using computer software, and a Food Pyramid Score was calculated to compare diets. The Mensink, Hegsted and other formulae were applied to estimate coronary heart disease risk factors. Higher fat diets are higher in saturated fats and cholesterol than current dietary guidelines and their long-term use would increase serum cholesterol levels and risk for CHD. Diets restricted in sugar intake would lower serum cholesterol levels and long-term risk for CHD; however, higher carbohydrate, higher fiber, lower fat diets would have the greatest effect in decreasing serum cholesterol concentrations and risk of CHD. While high fat diets may promote short-term weight loss, the potential hazards for worsening risk for progression of atherosclerosis override the short-term benefits. Individuals derive the greatest health benefits from diets low in saturated fat and high in carbohydrate and fiber: these increase sensitivity to insulin and lower risk for CHD.

Correlates of Dietary Intake in Youth with Diabetes: Results from the SEARCH for Diabetes in Youth Study

ERIC Educational Resources Information Center

Bortsov, Andrey; Liese, Angela D.; Bell, Ronny A.; Dabelea, Dana; D'Agostino, Ralph B., Jr.; Hamman, Richard F.; Klingensmith, Georgeanna J.; Lawrence, Jean M.; Maahs, David M.; McKeown, Robert; Marcovina, Santica M.; Thomas, Joan; Mayer-Davis, Elizabeth J.

2011-01-01

Objective: To explore demographic, socioeconomic, diabetes-related, and behavioral correlates of dietary intake of dairy, fruit, vegetables, sweetened soda, fiber, calcium, and saturated fat in youth with diabetes. Methods: Cross-sectional study of youth 10-22 years old with type 1 (T1DM, n = 2,176) and type 2 diabetes (T2DM, n = 365). Association…

A Comparison of Concentrations of Sodium and Related Nutrients (Potassium, Total Dietary Fiber, Total and Saturated Fat, and Total Sugar) in Private-Label and National Brands of Popular, Sodium-Contributing, Commercially Packaged Foods in the United States.

PubMed

Ahuja, Jaspreet K C; Pehrsson, Pamela R; Cogswell, Mary

2017-05-01

Private-label brands account for about one in four foods sold in US supermarkets. They provide value to consumers due to their low cost. We know of no US studies comparing the nutrition content of private-label products with corresponding national brand products. The objective was to compare concentrations of sodium and related nutrients (potassium, total dietary fiber, total and saturated fat, and total sugar) in popular sodium-contributing, commercially packaged foods by brand type (national or private-label brand). During 2010 to 2014, the Nutrient Data Laboratory of the US Department of Agriculture obtained 1,706 samples of private-label and national brand products from up to 12 locations nationwide and chemically analyzed 937 composites for sodium and related nutrients. The samples came from 61 sodium-contributing, commercially packaged food products for which both private-label and national brands were among the top 75% to 80% of brands for US unit sales. In this post hoc comparative analysis, the authors assigned a variable brand type (national or private label) to each composite and determined mean nutrient contents by brand type overall and by food product and type. The authors tested for significant differences (P<0.05) by brand type using independent sample t tests or Mann-Whitney U tests when appropriate. Overall for all foods sampled, differences between brand types were not statistically significant for any of the nutrients studied. However, differences in both directions exist for a few individual food products and food categories. Concentrations of sodium and related nutrients (potassium, total dietary fiber, total and saturated fat, and total sugar) do not differ systematically between private-label and national brands, suggesting that brand type is not a consideration for nutritional quality of foods in the United States. The study data provide public health officials with baseline nutrient content by brand type to help focus US sodium-reduction efforts. Published by Elsevier Inc.

Coconut endocarp and mesocarp as both biosorbents of dissolved hydrocarbons in fuel spills and as a power source when exhausted.

PubMed

Luis-Zarate, Victor Hugo; Rodriguez-Hernandez, Mayra Cecilia; Alatriste-Mondragon, Felipe; Chazaro-Ruiz, Luis Felipe; Rangel-Mendez, Jose Rene

2018-04-01

Health and environmental problems associated with the presence of toxic aromatic compounds in water from oil spills have motivated research to develop effective and economically viable strategies to remove these pollutants. In this work, coconut shell (endocarp), coconut fiber (mesocarp) and coconut shell with fiber (endocarp and mesocarp) obtained from coconut (Cocos nucifera) waste were evaluated as biosorbents of benzene, toluene and naphthalene from water, considering the effect of the solution pH (6-9) and the presence of dissolved organic matter (DOM) in natural water (14 mg/L). In addition, the heat capacity of saturated biosorbents was determined to evaluate their potential as an alternative power source to conventional fossil fuels. Tests of N 2 physisorption, SEM, elemental and fiber analysis, ATR-FTIR and acid-based titrations were performed in order to understand the materials' characteristics, and to elucidate the biosorbents' hydrocarbon adsorption mechanism. Coconut fiber showed the highest adsorption capacities (222, 96 and 5.85 mg/g for benzene, toluene and naphthalene, respectively), which was attributed to its morphologic characteristics and to its high concentration of phenolic groups, associated with the lignin structure. The pH of the solution did not have a significant influence on the removal of the contaminants, and the presence of DOM improved the adsorption capacities of aromatic hydrocarbons. The adsorption studies showed biphasic isotherms, which highlighted the strong affinity between the molecules adsorbed on the biosorbents and the aromatic compounds remaining in the solution. Finally, combustion heat analysis of coconut waste saturated with soluble hydrocarbons showed that the heat capacity increased from 4407.79 cal/g to 5064.43 ± 11.6 cal/g, which is comparable with that of woody biomass (3400-4000 cal/g): this waste biomass with added value could be a promising biofuel. Copyright © 2018 Elsevier Ltd. All rights reserved.

Erbium:ytterbium fiber-laser system delivering watt-level femtosecond pulses using divided pulse amplification

NASA Astrophysics Data System (ADS)

Herda, Robert; Zach, Armin

2015-03-01

We present an Erbium:Ytterbium codoped fiber-amplifer system based on Divided-Pulses-Amplification (DPA) for ultrashort pulses. The output from a saturable-absorber mode-locked polarization-maintaining (PM) fiber oscillator is amplified in a PM normal-dispersion Erbium-doped fiber. After this stage the pulses are positively chirped and have a duration of 2.0 ps at an average power of 93 mW. A stack of 5 birefringent Yttrium-Vanadate crystals divides these pulses 32 times. We amplify these pulses using a double-clad Erbium:Ytterbium codoped fiber pumped through a multimode fiber combiner. The pulses double pass the amplifier and recombine in the crystals using non-reciprocal polarization 90° rotation by a Faraday rotating mirror. Pulses with a duration of 144 fs are obtained after separation from the input beam using a polarizing beam splitter cube. These pulses have an average power of 1.85 W at a repetition rate of 80 MHz. The generation of femtosecond pulses directly from the amplifier was enabled by a positively chirped seed pulse, normally dispersive Yttrium-Vanadate crystals, and anomalously dispersive amplifier fibers. Efficient frequency doubling to 780 nm with an average power of 725 mW and a pulse duration of 156 fs is demonstrated. In summary we show a DPA setup that enables the generation of femtosecond pulses at watt-level at 1560 nm without the need for further external dechirping and demonstrate a good pulse quality by efficient frequency doubling. Due to the use of PM fiber components and a Faraday rotator the setup is environmentally stable.

Response Growth With Sound Level in Auditory-Nerve Fibers After Noise-Induced Hearing Loss

PubMed Central

Heinz, Michael G.; Young, Eric D.

2010-01-01

People with sensorineural hearing loss are often constrained by a reduced acoustic dynamic range associated with loudness recruitment; however, the neural correlates of loudness and recruitment are still not well understood. The growth of auditory-nerve (AN) activity with sound level was compared in normal-hearing cats and in cats with a noise-induced hearing loss to test the hypothesis that AN-fiber rate-level functions are steeper in impaired ears. Stimuli included best-frequency and fixed-frequency tones, broadband noise, and a brief speech token. Three types of impaired responses were observed. 1) Fibers with rate-level functions that were similar across all stimuli typically had broad tuning, consistent with outer-hair-cell (OHC) damage. 2) Fibers with a wide dynamic range and shallow slope above threshold often retained sharp tuning, consistent with primarily inner-hair-cell (IHC) damage. 3) Fibers with very steep rate-level functions for all stimuli had thresholds above approximately 80 dB SPL and very broad tuning, consistent with severe IHC and OHC damage. Impaired rate-level slopes were on average shallower than normal for tones, and were steeper in only limited conditions. There was less variation in rate-level slopes across stimuli in impaired fibers, presumably attributable to the lack of suppression-induced reductions in slopes for complex stimuli relative to BF-tone slopes. Sloping saturation was observed less often in impaired fibers. These results illustrate that AN fibers do not provide a simple representation of the basilar-membrane I/O function and suggest that both OHC and IHC damage can affect AN response growth. PMID:14534289

High resolution interrogation system for fiber Bragg grating (FBG) sensor application using radio frequency spectrum analyser

NASA Astrophysics Data System (ADS)

Muhammad, F. D.; Zulkifli, M. Z.; Harun, S. W.; Ahmad, H.

2013-05-01

In this paper, we propose a fiber Bragg grating (FBG) interrogation system for high resolution sensor application based on radio frequency (RF) generation technique by beating a single longitudinal mode (SLM) fiber ring laser with an external tunable laser source (TLS). The external TLS provides a constant wavelength (CW), functioning as the reference signal for the frequency beating technique. The TLS used has a constant output power and wavelength over time. The sensor signal is provided by the reflected wavelength of a typical fiber Bragg grating (FBG) in the SLM fiber ring laser, which consists of a 1 m long highly doped Erbium doped fiber as the gain medium. The key to ensure the SLM laser oscillation is the role of graphene as saturable absorber which is opposed to the commonly used unpumped erbiumdoped fiber and this consequently contributes to the simple and short cavity design of our proposed system. The signal from the SLM fiber ring laser, which is generated by the FBG in response to external changes, such as temperature, strain, air humidity and air movement, is heterodyned with the CW signal from the TLS at a 6 GHz photodetector using a 3-dB fused coupler to generate the frequency beating. This proposed system is experimentally demonstrated as a temperature sensor and the results shows that the frequency response of the system towards the changes in temperature is about 1.3 GHz/°C, taking into account the resolution bandwidth of 3 MHz of the radio frequency spectrum analyzer (RFSA).

Measurement of splanchnic photoplethysmographic signals using a new reflectance fiber optic sensor

NASA Astrophysics Data System (ADS)

Hickey, Michelle; Samuels, Neal; Randive, Nilesh; Langford, Richard M.; Kyriacou, Panayiotis A.

2010-03-01

Splanchnic organs are particularly vulnerable to hypoperfusion. Currently, there is no technique that allows for the continuous estimation of splanchnic blood oxygen saturation (SpO2). As a preliminary to developing a suitable splanchnic SpO2 sensor, a new reflectance fiber optic photoplethysmographic (PPG) sensor and processing system are developed. An experimental procedure to examine the effect of fiber source detector separation distance on acquired PPG signals is carried out before finalizing the sensor design. PPG signals are acquired from four volunteers for separation distances of 1 to 8 mm. The separation range of 3 to 6 mm provides the best quality PPG signals with large amplitudes and the highest signal-to-noise ratios (SNRs). Preliminary calculation of SpO2 shows that distances of 3 and 4 mm provide the most realistic values. Therefore, it is suggested that the separation distance in the design of a fiber optic reflectance pulse oximeter be in the range of 3 to 4 mm. Preliminary PPG signals from various splanchnic organs and the periphery are obtained from six anaesthetized patients. The normalized amplitudes of the splanchnic PPGs are, on average, approximately the same as those obtained simultaneously from the periphery. These observations suggest that fiber optic pulse oximetry may be a valid monitoring technique for splanchnic organs.

Continuous-wave to pulse regimes for a family of passively mode-locked lasers with saturable nonlinearity

NASA Astrophysics Data System (ADS)

Dikandé, Alain M.; Voma Titafan, J.; Essimbi, B. Z.

2017-10-01

The transition dynamics from continuous-wave to pulse regimes of operation for a generic model of passively mode-locked lasers with saturable absorbers, characterized by an active medium with non-Kerr nonlinearity, are investigated analytically and numerically. The system is described by a complex Ginzburg-Landau equation with a general m:n saturable nonlinearity (i.e {I}m/{(1+{{Γ }}I)}n, where I is the field intensity and m and n are two positive numbers), coupled to a two-level gain equation. An analysis of stability of continuous waves, following the modulational instability approach, provides a global picture of the self-starting dynamics in the system. The analysis reveals two distinct routes depending on values of the couple (m, n), and on the dispersion regime: in the normal dispersion regime, when m = 2 and n is arbitrary, the self-starting requires positive values of the fast saturable absorber and nonlinearity coefficients, but negative values of these two parameters for the family with m = 0. However, when the spectral filter is negative, the laser can self-start for certain values of the input field and the nonlinearity saturation coefficient Γ. The present work provides a general map for the self-starting mechanisms of rare-earth doped figure-eight fiber lasers, as well as Kerr-lens mode-locked solid-state lasers.

Effect of Mechanical Impact Energy on the Sorption and Diffusion of Moisture in Reinforced Polymer Composite Samples on Variation of Their Sizes

NASA Astrophysics Data System (ADS)

Startsev, V. O.; Il'ichev, A. V.

2018-05-01

The effect of mechanical impact energy on the sorption and diffusion of moisture in polymer composite samples on variation of their sizes was investigated. Square samples, with sides of 40, 60, 80, and 100 mm, made of a KMKU-2m-120.E0,1 carbon-fiber and KMKS-2m.120.T10 glass-fiber plastics with different resistances to calibrated impacts, were compared. Impact loading diagrams of the samples in relation to their sizes and impact energy were analyzed. It is shown that the moisture saturation and moisture diffusion coefficient of the impact-damaged materials can be modeled by Fick's second law with account of impact energy and sample sizes.

Multi-Wavelength Q-Switched Ytterbium-Doped Fiber Laser with Multi-Walled Carbon Nanotubes

NASA Astrophysics Data System (ADS)

Al-Masoodi, A. H. H.; Ahmed, M. H. M.; Arof, H.; Harun, S. W.

2018-03-01

We demonstrate a passively multi-wavelength Q-switched Ytterbium-doped fiber laser (YDFL) based on a multi-wall carbon nanotubes embedded in polyethylene oxide film as saturable absorber. The YDFL generates a stable multi-wavelength with spacing of 1.9 nm as the 980 nm pump power is fixed within 62. 4 mW and 78.0 mW. The repetition rate of the laser is tunable from 10.41 to 29.04 kHz by increasing the pump power from the threshold power of 62.4 mW to 78 mW. At 78 mW pump power, the maximum pulse energy of 38 nJ and the shortest pulse width of 8.87 µs are obtained.

Studies on unsaturated flow in dual-scale fiber fabrics

NASA Astrophysics Data System (ADS)

Yan, Fei; Yan, Shilin; Li, Yongjing

2018-03-01

Fiber fabrics in liquid composite molding (LCM) can be recognized as a dual-scale structure. As sink theory developed, this unsaturated flow behavior has already been simulated successfully; however, most of simulated results based on a unit cell under ideal status, thus making results were not agreement with experiment. In this study, an experimental method to establish sink function was proposed. After compared the simulation results by this sink function, it shows high accuracy with the experimental data. Subsequently, the key influencing factors for unsaturated flow have been further investigated; results show that the filling time for unsaturated flow was much longer than saturated flow. In addition, the injection pressure and permeability were the key factors lead to unsaturated flow.

Mode-locked fiber laser using SU8 resist incorporating carbon nanotubes

NASA Astrophysics Data System (ADS)

Hernandez-Romano, Ivan; Mandridis, Dimitrios; May-Arrioja, Daniel A.; Sanchez-Mondragon, Jose J.; Delfyett, Peter J.

2011-06-01

We report the fabrication of a saturable absorber made of a novel polymer SU8 doped with Single Wall Carbon Nanotubes (SWCNTs). A passive mode-locked ring cavity fiber laser was built with a 100 μm thick SU8/SWCNT film inserted between two FC/APC connectors. Self-starting passively mode-locked lasing operation was observed at 1572.04 nm, with a FWHM of 3.26 nm. The autocorrelation trace was 1.536 ps corresponding to a pulse-width of 871 fs. The time-bandwidth product was 0.344, which is close enough to transform-limited sech squared pulses. The repetition rate was 21.27 MHz, and a maximum average output power of 1 mW was also measured.

Nonlinear Optical Fiber Arrays for Limiting Application

DTIC Science & Technology

2006-09-05

Absorption [ RSA ], Two-Photon Absorption [TPA] and Excited State Absorption [ESA] or Nonlinear Scattering properties [NS] (e.g. carbon black suspension...practical implementation: I. "Saturation Effect and Dynamic Range" - In general, RSA materials have low switching threshold (<<pJ), but are (linearly...transition between the molecular levels involved, RSA materials can be easily ’bleached’, i.e. the absorption electronic state is depopulated by the laser. TPA

Frozen yogurt and ice cream were less healthy than yogurt, and adding toppings reduced their nutrition value: evidence from 1999-2014 National Health and Nutrition Examination Survey.

PubMed

An, Ruopeng; Jiang, Ning

2017-06-01

It was hypothesized that frozen yogurt and ice cream would be less healthy than yogurt. We examined daily energy and nutrient intake from yogurt, frozen yogurt, and ice cream among US adults. In-person 24-hour dietary recall data (n=6453) came from the 1999-2014 National Health and Nutrition Examination Survey. Regression analyses were performed to examine the differences in energy/nutrient intake from frozen yogurt and ice cream (with/without toppings) in comparison to yogurt. Approximately 5.3%, 0.9%, and 14.3% of US adults consumed yogurt, frozen yogurt, and ice cream on any given day, respectively. Among frozen yogurt and ice cream consumers, 29.7% and 14.8% added toppings to their consumption, respectively. Compared with yogurt, frozen yogurt consumption with and without toppings was associated with increased daily energy intake by 214.6 and 97.9kj, respectively; whereas ice cream consumption with and without toppings was associated with increased daily energy intake by 427.2 and 343.5kj, respectively. Compared with yogurt, frozen yogurt consumption was associated with a decreased intake of most vitamins/minerals under examination, but increased intake of sugar, total/saturated fat, cholesterol, fiber, and iron. Adding toppings to frozen yogurt further increased total and saturated fat intake. Compared with yogurt, ice cream consumption was associated with a decreased intake of multiple micronutrients, but increased intake of sugar, total/saturated fat, cholesterol, fiber, vitamins A and E, and iron. Adding toppings to ice cream further increased sugar intake. In conclusion, frozen yogurt and ice cream were less healthy than yogurt, and adding toppings made them even less desirable. Copyright © 2017 Elsevier Inc. All rights reserved.

Mechanical properties of neat polymer matrix materials and their unidirectional carbon fiber-reinforced composites

NASA Technical Reports Server (NTRS)

Zimmerman, Richard S.; Adams, Donald F.

1988-01-01

The mechanical properties of two neat resin systems for use in carbon fiber epoxy composites were characterized. This included tensile and shear stiffness and strengths, coefficients of thermal and moisture expansion, and fracture toughness. Tests were conducted on specimens in the dry and moisture-saturated states, at temperatures of 23, 82 and 121 C. The neat resins tested were American Cyanamid 1806 and Union Carbide ERX-4901B(MPDA). Results were compared to previously tested neat resins. Four unidirectional carbon fiber reinforced composites were mechanically characterized. Axial and transverse tension and in-plane shear strengths and stiffness were measured, as well as transverse coefficients of thermal and moisture expansion. Tests were conducted on dry specimens only at 23 and 100 C. The materials tested were AS4/3502, AS6/5245-C, T300/BP907, and C6000/1806 unidirectional composites. Scanning electron microscopic examination of fracture surfaces was performed to permit the correlation of observed failure modes with the environmental test conditions.

Wavelength-encoded optical psychrometer for relative humidity measurement

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

Montanini, Roberto

2007-02-15

In this article an optical psychrometer, in which temperature measurements are performed by means of two fiber Bragg grating sensors used as dry-bulb and wet-bulb thermometers, is introduced. The adopted design exploits both the high accuracy of psychrometric-based relative humidity measurements with acknowledged advantages of wavelength-encoded fiber optic sensing. Important metrological issues that have been addressed in the experimental work include calibration of the fiber Bragg grating temperature sensors, evaluation of response time, sensitivity, hysteresis, linearity, and accuracy. The calibration results give confidence that, with the current experimental setup, measurement of temperature can be done with an uncertainty of {+-}0.2more » deg. C and a resolution of 0.1 deg. C. A detailed uncertainty analysis is also presented in the article to investigate the effects produced by different sources of error on the combined standard uncertainty u{sub c}(U) of the relative humidity measurement, which has been estimated to be roughly within {+-}2% in the range close to saturation.« less

Wavelength-encoded optical psychrometer for relative humidity measurement.

PubMed

Montanini, Roberto

2007-02-01

In this article an optical psychrometer, in which temperature measurements are performed by means of two fiber Bragg grating sensors used as dry-bulb and wet-bulb thermometers, is introduced. The adopted design exploits both the high accuracy of psychrometric-based relative humidity measurements with acknowledged advantages of wavelength-encoded fiber optic sensing. Important metrological issues that have been addressed in the experimental work include calibration of the fiber Bragg grating temperature sensors, evaluation of response time, sensitivity, hysteresis, linearity, and accuracy. The calibration results give confidence that, with the current experimental setup, measurement of temperature can be done with an uncertainty of +/- 0.2 degrees C and a resolution of 0.1 degrees C. A detailed uncertainty analysis is also presented in the article to investigate the effects produced by different sources of error on the combined standard uncertainty uc(U) of the relative humidity measurement, which has been estimated to be roughly within +/-2% in the range close to saturation.

Photonic textiles for pulse oximetry.

PubMed

Rothmaier, Markus; Selm, Bärbel; Spichtig, Sonja; Haensse, Daniel; Wolf, Martin

2008-08-18

Biomedical sensors, integrated into textiles would enable monitoring of many vitally important physiological parameters during our daily life. In this paper we demonstrate the design and performance of a textile based pulse oximeter, operating on the forefinger tip in transmission mode. The sensors consisted of plastic optical fibers integrated into common fabrics. To emit light to the human tissue and to collect transmitted light the fibers were either integrated into a textile substrate by embroidery (producing microbends with a nominal diameter of 0.5 to 2 mm) or the fibers inside woven patterns have been altered mechanically after fabric production. In our experiments we used a two-wavelength approach (690 and 830 nm) for pulse wave acquisition and arterial oxygen saturation calculation. We have fabricated different specimens to study signal yield and quality, and a cotton glove, equipped with textile based light emitter and detector, has been used to examine movement artifacts. Our results show that textile-based oximetry is feasible with sufficient data quality and its potential as a wearable health monitoring device is promising.

A Fiber-Optic Current Sensor for Lightning Measurement Applications

NASA Technical Reports Server (NTRS)

Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George N.

2015-01-01

An optical-fiber sensor based on Faraday Effect is developed for measuring total lightning electric current. It has many unique capabilities not possible with traditional current sensors. Designed for aircraft installation, the sensor is lightweight, non-conducting, structure-conforming, and is immune to electromagnetic interference, hysteresis and saturation. It can also be used on windmills, lightning towers, and can help validate lightning detection network measurements. Faraday Effect causes light polarization to rotate when the fiber is exposed to a magnetic field in the direction of light propagation. Thus, the magnetic field strength can be determined from the light polarization change. By forming closed fiber loops and applying Ampere's law, measuring the total light rotation yields the total current enclosed. The broadband, dual-detector, reflective polarimetric scheme allows measurement of both DC component and AC waveforms with about 60 dB dynamic range. Three sensor systems were built with different sensitivities from different laser wavelengths. Operating at 850nm, the first system uses twisted single-mode fiber and has a 150 A - 150 KA range. The second system operates at 1550nm, uses spun polarization maintaining fiber, and can measure 400 A - 400 KA. Both systems were validated with rocket-triggered lightning measurements and achieved excellent results when compared to a resistive shunt. The third system operates at 1310nm, uses spun polarization maintaining fiber, and can measure approximately 300 A - 300 KA. High current measurements up to 200 KA were demonstrated at a commercial lightning test facility. The system was recently installed on an aircraft and flown near icing weather conditions.

A fiber-optic current sensor for lightning measurement applications

NASA Astrophysics Data System (ADS)

Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George N.

2015-05-01

An optical-fiber sensor based on Faraday Effect is developed for measuring total lightning electric current. It has many unique capabilities not possible with traditional current sensors. Designed for aircraft installation, the sensor is lightweight, non-conducting, structure-conforming, and is immune to electromagnetic interference, hysteresis and saturation. It can also be used on windmills, lightning towers, and can help validate lightning detection network measurements. Faraday Effect causes light polarization to rotate when the fiber is exposed to a magnetic field in the direction of light propagation. Thus, the magnetic field strength can be determined from the light polarization change. By forming closed fiber loops and applying Ampere's law, measuring the total light rotation yields the total current enclosed. The broadband, dual-detector, reflective polarimetric scheme allows measurement of both DC component and AC waveforms with about 60 dB dynamic range. Three sensor systems were built with different sensitivities from different laser wavelengths. Operating at 850nm, the first system uses twisted single-mode fiber and has a 150 A - 150 KA range. The second system operates at 1550nm, uses spun polarization maintaining fiber, and can measure 400 A - 400 KA. Both systems were validated with rocket-triggered lightning measurements and achieved excellent results when compared to a resistive shunt. The third system operates at 1310nm, uses spun polarization maintaining fiber, and can measure approximately 300 A - 300 KA. High current measurements up to 200 KA were demonstrated at a commercial lightning test facility. The system was recently installed on an aircraft and flown near icing weather conditions.

Experimental approach to investigate the constrained recovery behavior of coiled monofilament polymer fibers

NASA Astrophysics Data System (ADS)

Mendes, S. S.; Nunes, L. C. S.

2017-11-01

The aim of this work is to propose a new approach for investigating the thermo-mechanical behavior of coiled oriented polymer fibers with fixed ends and promote an understanding of the actuation response of coiled polymers in constrained recovery applications. In the proposed experimental methodology, a coiled fiber was pre-stretched by 50% and the distance between its ends remained constant, then it was subjected to a heating-cooling cycle ranging from 30 °C to 120 °C and the induced restoring force was measured. Based on these measurements, axial deformation and shear strain were obtained from full-field displacements extracted by the digital image correlation method from images of the coiled fiber. Three coiled fibers with different initial pitch angles were manufactured, and samples with lengths of 15 mm and 20 mm were tested. Bias angles and coil radius were also estimated using the experimental data associated with the helical spring theory. Results show that significant shape changes can be noticed above the glass transition temperature (47 °C), and these changes induce variation in the resultant forces. The effects of thermal softening and thermal contraction for a modest negative thermal expansion coefficient became evident at temperatures ranging from ∼47 °C to ∼90 °C, while the response of a coiled homochiral polymer fiber was achieved at temperatures close to 90 °C. During the cooling process, saturated states of the axial deformation and shear strain of the coiled fibers were observed at temperatures between 120 °C and 100 °C.

Effect of strain on actomyosin kinetics in isometric muscle fibers.

PubMed

Siththanandan, V B; Donnelly, J L; Ferenczi, M A

2006-05-15

Investigations were conducted into the biochemical and mechanical states of cross-bridges during isometric muscle contraction. Rapid length steps (3 or 6 nm hs(-1)) were applied to rabbit psoas fibers, permeabilized and isometric, at either 12 degrees C or 20 degrees C. Fibers were activated by photolysis of P(3)-1-(2-nitrophenyl)-ethyl ester of ATP infused into rigor fibers at saturating Ca(2+). Sarcomere length, tension, and phosphate release were recorded-the latter using the MDCC-PBP fluorescent probe. A reduction in strain, induced by a rapid release step, produced a short-lived acceleration of phosphate release. Rates of the phosphate transient and that of phases 3 and 4 of tension recovery were unaffected by step size but were elevated at higher temperatures. In contrast the amplitude of the phosphate transient was smaller at 20 degrees C than 12 degrees C. The presence of 0.5 or 1.0 mM added ADP during a release step reduced both the rate of tension recovery and the poststep isometric tension. A kinetic scheme is presented to simulate the observed data and to precisely determine the rate constants for the elementary steps of the ATPase cycle.

High spatial sampling light-guide snapshot spectrometer

PubMed Central

Wang, Ye; Pawlowski, Michal E.; Tkaczyk, Tomasz S.

2017-01-01

A prototype fiber-based imaging spectrometer was developed to provide snapshot hyperspectral imaging tuned for biomedical applications. The system is designed for imaging in the visible spectral range from 400 to 700 nm for compatibility with molecular imaging applications as well as satellite and remote sensing. An 81 × 96 pixel spatial sampling density is achieved by using a custom-made fiber-optic bundle. The design considerations and fabrication aspects of the fiber bundle and imaging spectrometer are described in detail. Through the custom fiber bundle, the image of a scene of interest is collected and divided into discrete spatial groups, with spaces generated in between groups for spectral dispersion. This reorganized image is scaled down by an image taper for compatibility with following optical elements, dispersed by a prism, and is finally acquired by a CCD camera. To obtain an (x, y, λ) datacube from the snapshot measurement, a spectral calibration algorithm is executed for reconstruction of the spatial–spectral signatures of the observed scene. System characterization of throughput, resolution, and crosstalk was performed. Preliminary results illustrating changes in oxygen-saturation in an occluded human finger are presented to demonstrate the system’s capabilities. PMID:29238115

The effect of dietary fat content on phospholipid fatty acid profile is muscle fiber type dependent.

PubMed

Janovská, Alena; Hatzinikolas, George; Mano, Mark; Wittert, Gary A

2010-04-01

A high-saturated-fat diet (HFD) induces obesity and insulin resistance (IR). IR has been linked to alterations and increased saturation in the phospholipid composition of skeletal muscles. We aimed to determine whether HFD feeding affects fatty acid (FA) membrane profile in a muscle fiber type-specific manner. We measured phospholipid FAs and expression of FA synthesis genes in oxidative soleus (SOL) and glycolytic extensor digitorum longus (EDL) muscles from rats fed either standard chow (standard laboratory diet, SLD) or a HFD. The HFD increased fat mass, plasma insulin, and leptin levels. Compared with EDL, SOL muscles preferentially accumulated C18 over C16 FAs and n-6 over n-3 polyunsaturated FAs (PUFAs) on either diet. With the HFD, SOL muscles contained more n-9 monounsaturated FAs (MUFAs) and n-6 PUFAs and less n-7 MUFAs and n-3 PUFAs than EDL muscles and had lower unsaturation index, a pattern known to be associated with IR. Stearoyl-CoA desaturase-1 expression was approximately 13-fold greater in EDL than in SOL muscles but did not change with the HFD in either muscle. The expression of Elongase-5 was higher, and that of Elongase-6 (Elovl6) was lower in EDL compared with SOL muscles with both diets. In EDL muscles, the expression of Elovl6 was lower in the HFD than in the SLD. The pattern of FA uptake, expression, and diet-induced changes in FA desaturating and elongating enzymes maintained higher FA unsaturation in EDL muscles. Accordingly, the fiber type composition of skeletal muscles and their distribution may be important in the development and progression of obesity and IR.

A dietary portfolio approach to cholesterol reduction: combined effects of plant sterols, vegetable proteins, and viscous fibers in hypercholesterolemia.

PubMed

Jenkins, David J A; Kendall, Cyril W C; Faulkner, Dorothea; Vidgen, Edward; Trautwein, Elke A; Parker, Tina L; Marchie, Augustine; Koumbridis, George; Lapsley, Karen G; Josse, Robert G; Leiter, Lawrence A; Connelly, Philip W

2002-12-01

Plant sterols, soy proteins, and viscous fibers are advised for cholesterol reduction but their combined effect has never been tested. We therefore assessed their combined effect on blood lipids in hyperlipidemic subjects who were already consuming a low-saturated fat, low-cholesterol diet before starting the study. The test (combination) diet was 1 month in duration and was very low in saturated fat and high in plant sterols (1 g/1,000 kcal), soy protein (23 g/1,000 kcal), and viscous fibers (9 g/1,000 kcal) obtained from foods available in supermarkets and health food stores. One subject also completed 2 further diet periods: a low-fat control diet and a control diet plus 20 mg/d lovastatin. Fasting blood lipids, blood pressure, and body weight were measured prior to and at weekly intervals during the study. The combination diet was rated as acceptable and very filling. The diet reduced low-density lipoprotein (LDL)-cholesterol by 29.0% +/- 2.7% (P <.001) and the ratio of LDL-cholesterol to high-density lipoprotein (HDL)-cholesterol by 26.5% +/- 3.4% (P <.001). Near maximal reductions were seen by week 2. In the subject who took Mevacor and control diets each for 4 weeks, the reduction in LDL:HDL-cholesterol on Mevacor was similar to the combination diet. We conclude that acceptable diets of foods from supermarkets and health food stores that contain recognized cholesterol-lowering dietary components in combination (a dietary portfolio) may be as effective as the starting dose of older first-line drugs in managing hypercholesterolemia. Copyright 2002, Elsevier Science (USA). All rights reserved.

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

Cantrill, E.R.; Ray, A.; Stevens, M.G.

The interfacial bond between fiber and matrix is one of the most important factors influencing fiber-reinforced composites. This is particularly apparent in cellulose wood pulp reinforced cement/quartz composites cured by autoclaving under saturated steam at 180 C. Scanning electron microscopy (SEM) studies have shown that there is little modification of the surface of the hydrated calcium silicate matrix immediately adjacent to the cellulose fiber surface, provided the cellulose fiber is relatively free from lignin, hemicelluloses, or chemicals from the pulping process. Coutts & Campbell (1979) in their investigation of water cured cement composites, applied several commercial coupling agents to cellulosemore » fibres and established that two of these agents significantly increased the strength of the interfacial bond. In this paper, the surface of cellulose fibres was modified by sodium silicate, CTBN [carboxy terminated butadiene nitrile] and ATBN [amino terminated butadiene nitrile] in order to enhance the interfacial bond, and also to increase the resistance of the cellulose to oxidation, alkaline or thermal degradation, and algal attack. Algal attack can occur as the calcium silicate matrix is neutralized by atmospheric carbonation, especially in external wall board applications of the sheet composite. In addition, suitable coatings will protect the cellulose fiber from degradation arising from the presence of elevated temperature and alkaline solutions during the autoclaving process. Cellulose reinforced composites with substandard strengths, due to inhibited autoclave reactions, cannot be reautoclaved as the resultant material is too brittle due, in part, to the degradation of the cellulose fiber.« less

Intramyocardial oxygen transport by quantitative diffuse reflectance spectroscopy in calves

NASA Astrophysics Data System (ADS)

Lindbergh, Tobias; Larsson, Marcus; Szabó, Zoltán; Casimir-Ahn, Henrik; Strömberg, Tomas

2010-03-01

Intramyocardial oxygen transport was assessed during open-chest surgery in calves by diffuse reflectance spectroscopy using a small intramuscular fiber-optic probe. The sum of hemo- and myoglobin tissue fraction and oxygen saturation, the tissue fraction and oxidation of cytochrome aa3, and the tissue fraction of methemoglobin were estimated using a calibrated empirical light transport model. Increasing the oxygen content in the inhaled gas, 21%-50%-100%, in five calves (group A) gave an increasing oxygen saturation of 19+/-4%, 24+/-5%, and 28+/-8% (p<0.001, ANOVA repeated measures design) and mean tissue fractions of 1.6% (cytochrome aa3) and 1.1% (hemo- and myoglobin). Cardiac arrest in two calves gave an oxygen saturation lower than 5%. In two calves (group B), a left ventricular assistive device (LVAD pump) was implanted. Oxygen saturation in group B animals increased with LVAD pump speed (p<0.001, ANOVA) and with oxygen content in inhaled gas (p<0.001, ANOVA). The cytochrome aa3 oxidation level was above 96% in both group A and group B calves, including the two cases involving cardiac arrest. In conclusion, the estimated tissue fractions and oxygenation/oxidation levels of the myocardial chromophores during respiratory and hemodynamic provocations were in agreement with previously presented results, demonstrating the potential of the method.

Noninvasive measurement of internal jugular venous oxygen saturation by photoacoustic imaging

NASA Astrophysics Data System (ADS)

Garcia-Uribe, Alejandro; Erpelding, Todd N.; Ke, Haixin; Reddy, Kavya; Sharma, Anshuman; Wang, Lihong V.

2014-03-01

The metabolic rate and oxygen consumption of the brain is reflected in jugular venous oxygen saturation. In many clinical conditions, such as head trauma, stroke, and low cardiac output states, the brain is at risk for hypoxic-ischemic injury. The current gold standard for monitoring brain oxygenation is invasive and requires jugular vein catheterization under fluoroscopic guidance; and therefore it is rarely used. Photo-acoustic tomography in combination with ultrasound can be used to estimate oxygen saturation of the internal jugular vein in real-time. This noninvasive method will enable earlier detection and prevention of impending hypoxic brain injury. A wavelength-tunable dye laser pumped by a Nd:YAG laser delivers light through an optical fiber bundle, and a modified commercial ultrasound imaging system (Philips iU22) detects both the pulse-echo ultrasound (US) and photoacoustic (PA) signals. A custom-built multichannel data acquisition system renders co-registered ultrasound and photoacoustic images at 5 frames per second. After the jugular vein was localized in healthy volunteers, dualwavelength PA images were used to calculate the blood hemoglobin oxygen saturation from the internal jugular vein in vivo. The preliminary results raise confidence that this emerging technology can be used clinically as an accurate, noninvasive indicator of cerebral oxygenation.

Fabrication of T142 Tank Track Pads for Evaluation of a Rubber-Kevlar Composite Compound

DTIC Science & Technology

1982-06-01

fully developed with highly saturated rubbers such as butyl or ROYALENE® ( EPDM ) A-3 ...PERIOD COVERED Fabrication of T142 Tank Track Pads for Evaluation of a Rubber -Kevlar Composite FINAL Compound S. PERFORMING ORG. REPORT NUMBER 7. AUTHOR...developed for evaluation in T142 tank track pads. Bonding of the rubber to the fiber was achieved by addition of bonding agents to the compound. 175, T142

Threshold for ion movements in wood cell walls below fiber saturation observed by X-ray fluorescence microscopy (XFM)

Treesearch

Samuel L. Zelinka; Sophie-Charlotte Gleber; Stefan Vogt; Gabriela M. Rodriguez Lopez; Joseph E. Jakes

2015-01-01

Diffusion of chemicals and ions through the wood cell wall plays an important role in wood damage mechanisms. In the present work, free diffusion of ions through wood secondary walls and middle lamellae has been investigated as a function of moisture content (MC) and anatomical direction. Various ions (K, Cl, Zn, Cu) were injected into selected regions of 2 ìm thick...

Optimization of CW Fiber Lasers With Strong Nonlinear Cavity Dynamics

NASA Astrophysics Data System (ADS)

Shtyrina, O. V.; Efremov, S. A.; Yarutkina, I. A.; Skidin, A. S.; Fedoruk, M. P.

2018-04-01

In present work the equation for the saturated gain is derived from one-level gain equations describing the energy evolution inside the laser cavity. It is shown how to derive the parameters of the mathematical model from the experimental results. The numerically-estimated energy and spectrum of the signal are in good agreement with the experiment. Also, the optimization of the output energy is performed for a given set of model parameters.

Transmission Nonreciprocity in a Mutually Coupled Circulating Structure

NASA Astrophysics Data System (ADS)

He, Bing; Yang, Liu; Jiang, Xiaoshun; Xiao, Min

2018-05-01

Breaking Lorentz reciprocity was believed to be a prerequisite for nonreciprocal transmissions of light fields, so the possibility of nonreciprocity by linear optical systems was mostly ignored. We put forward a structure of three mutually coupled microcavities or optical fiber rings to realize optical nonreciprocity. Although its couplings with the fields from two different input ports are constantly equal, such system transmits them nonreciprocally either under the saturation of an optical gain in one of the cavities or with the asymmetric couplings of the circulating fields in different cavities. The structure made up of optical fiber rings can perform nonreciprocal transmissions as a time-independent linear system without breaking Lorentz reciprocity. Optical isolation for inputs simultaneously from two different ports and even approximate optical isolator operations are implementable with the structure.

Fatigue damage in cross-ply titanium metal matrix composites containing center holes

NASA Technical Reports Server (NTRS)

Bakuckas, J. G., Jr.; Johnson, W. S.; Bigelow, C. A.

1992-01-01

The development of fatigue damage in (0/90) sub SCS-6/TI-15-3 laminates containing center holes was studied. Stress levels required for crack initiation in the matrix were predicted using an effective strain parameter and compared to experimental results. Damage progression was monitored at various stages of fatigue loading. In general, a saturated state of damage consisting of matrix cracks and fiber matrix debonding was obtained which reduced the composite modulus. Matrix cracks were bridged by the 0 deg fibers. The fatigue limit (stress causing catastrophic fracture of the laminates) was also determined. The static and post fatigue residual strengths were accurately predicted using a three dimensional elastic-plastic finite element analysis. The matrix damage that occurred during fatigue loading significantly reduced the notched strength.

[INVITED] Porphyrin-nanoassembled fiber-optic gas sensor fabrication: Optimization of parameters for sensitive ammonia gas detection

NASA Astrophysics Data System (ADS)

Korposh, Sergiy; Kodaira, Suguru; Selyanchyn, Roman; Ledezma, Francisco H.; James, Stephen W.; Lee, Seung-Woo

2018-05-01

Highly sensitive fiber-optic ammonia gas sensors were fabricated via layer-by-layer deposition of poly(diallyldimethylammonium chloride) (PDDA) and tetrakis(4-sulfophenyl)porphine (TSPP) onto the surface of the core of a hard-clad multimode fiber that was stripped of its polymer cladding. The effects of film thickness, length of sensing area, and depth of evanescent wave penetration were investigated to clearly understand the sensor performance. The sensitivity of the fiber-optic sensor to ammonia was linear in the concentration range of 0.5-50 ppm and the response and recovery times were less than 3 min, with a limit of detection of 0.5 ppm, when a ten-cycle PDDA/TSPP film was assembled on the surface of the core along a 1 cm-long stripped section of the fiber. The sensor's response towards ammonia was also checked under different relative humidity conditions and a simple statistical data treatment approach, principal component analysis, demonstrated the feasibility of ammonia sensing in environmental relative humidity ranging from dry 7% to highly saturated 80%. Penetration depths of the evanescent wave for the optimal sensor configuration were estimated to be 30 and 33 nm at wavelengths of 420 and 706 nm, which are in a good agreement with the thickness of the 10-cycle deposited film (ca. 30 nm).

Application of active distribute temperature sensing and fiber optic as sensors to determinate the unsaturated hydraulic conductivity curve

NASA Astrophysics Data System (ADS)

Zubelzu, Sergio; Rodriguez-Sinobas, Leonor; Sobrino, Fernando

2017-04-01

The development of methodologies for the characterization of soil water content through the use of distribute temperature sensing and fiber optic cable has allowed for modelling with high temporal and spatial accuracy water movement in soils. One of the advantage of using fiber optic as a sensor, compared with the traditional point water probes, is the possibility to measure the variable continuously along the cable every 0.125 m (up to a cable length of 1500) and every second. Traditionally, applications based on fiber optic as a soil water sensor apply the active heated fiber optic technique AHFO to follow the evolution soil water content during and after irrigation events or for hydrologic characterization. However, this paper accomplishes an original experience by using AHFO as a sensor to characterize the soil hydraulic conductivity curve in subsaturated conditions. The non lineal nature between the hidraulic conductivity curve and soil water, showing high slope in the range close to saturation ) favors the AHFO a most suitable sensor due to its ability to measure the variable at small time and length intervals. Thus, it is possible to obtain accurate and a large number of data to be used to estimate the hydraulic conductivity curve from de water flow general equation by numerical methods. Results are promising and showed the feasibility of this technique to estimate the hydraulic conductivity curve for subsaturated soils .

Chain Ends and the Ultimate Tensile Strength of Polyethylene Fibers

NASA Astrophysics Data System (ADS)

O'Connor, Thomas C.; Robbins, Mark O.

Determining the tensile yield mechanisms of oriented polymer fibers remains a challenging problem in polymer mechanics. By maximizing the alignment and crystallinity of polyethylene (PE) fibers, tensile strengths σ ~ 6 - 7 GPa have been achieved. While impressive, first-principal calculations predict carbon backbone bonds would allow strengths four times higher (σ ~ 20 GPa) before breaking. The reduction in strength is caused by crystal defects like chain ends, which allow fibers to yield by chain slip in addition to bond breaking. We use large scale molecular dynamics (MD) simulations to determine the tensile yield mechanism of orthorhombic PE crystals with finite chains spanning 102 -104 carbons in length. The yield stress σy saturates for long chains at ~ 6 . 3 GPa, agreeing well with experiments. Chains do not break but always yield by slip, after nucleation of 1D dislocations at chain ends. Dislocations are accurately described by a Frenkel-Kontorova model, parametrized by the mechanical properties of an ideal crystal. We compute a dislocation core size ξ = 25 . 24 Å and determine the high and low strain rate limits of σy. Our results suggest characterizing such 1D dislocations is an efficient method for predicting fiber strength. This research was performed within the Center for Materials in Extreme Dynamic Environments (CMEDE) under the Hopkins Extreme Materials Institute at Johns Hopkins University. Financial support was provided by Grant W911NF-12-2-0022.

WS₂ as a saturable absorber for ultrafast photonic applications of mode-locked and Q-switched lasers.

PubMed

Wu, Kan; Zhang, Xiaoyan; Wang, Jun; Li, Xing; Chen, Jianping

2015-05-04

Two-dimensional (2D) nanomaterials, especially the transition metal sulfide semiconductors, have drawn great interests due to their potential applications in viable photonic and optoelectronic devices. In this work, 2D tungsten disulfide (WS2) based saturable absorber (SA) for ultrafast photonic applications was demonstrated. WS2 nanosheets were prepared using liquid-phase exfoliation method and embedded in polyvinyl alcohol (PVA) thin film for the practical usage. Saturable absorption was discovered in the WS2-PVA SA at the telecommunication wavelength near 1550 nm. By incorporating WS2-PVA SA into a fiber laser cavity, both stable mode locking operation and Q-switching operation were achieved. In the mode locking operation, the laser obtained femtosecond output pulse width and high spectral purity in the radio frequency spectrum. In the Q-switching operation, the laser had tunable repetition rate and output pulse energy of a few tens of nano joule. Our findings suggest that few-layer WS2 nanosheets embedded in PVA thin film are promising nonlinear optical materials for ultrafast photonic applications as a mode locker or Q-switcher.

Image-guided optical measurement of blood oxygen saturation within capillary vessels (Conference Presentation)

NASA Astrophysics Data System (ADS)

Akons, Kfir; Zeidan, Adel; Yeheskely-Hayon, Daniella; Minai, Limor; Yelin, Dvir

2016-03-01

Values of blood oxygenation levels are useful for assessing heart and lung conditions, and are frequently monitored during routine patient care. Independent measurement of the oxygen saturation in capillary blood, which is significantly different from that of arterial blood, is important for diagnosing tissue hypoxia and for increasing the accuracy of existing techniques that measure arterial oxygen saturation. Here, we developed a simple, non-invasive technique for measuring the reflected spectra from individual capillary vessels within a human lip, allowing local measurement of the blood oxygen saturation. The optical setup includes a spatially incoherent broadband light that was focused onto a specific vessel below the lip surface. Backscattered light was imaged by a camera for identifying a target vessel and pointing the illumination beam to its cross section. Scattered light from the vessel was then collected by a single-mode fiber and analyzed by a fast spectrometer. Spectra acquired from small capillary vessels within a volunteer lip showed the characteristic oxyhemoglobin absorption bands in real time and with a high signal-to-noise ratio. Measuring capillary oxygen saturation using this technique would potentially be more accurate compared to existing pulse oximetry techniques due to its insensitivity to the patient's skin color, pulse rate, motion, and medical condition. It could be used as a standalone endoscopic technique for measuring tissue hypoxia or in conjunction with conventional pulse oximetry for a more accurate measurement of oxygen transport in the body.

Effect of 17 days of bed rest on peak isometric force and unloaded shortening velocity of human soleus fibers

NASA Technical Reports Server (NTRS)

Widrick, J. J.; Romatowski, J. G.; Bain, J. L.; Trappe, S. W.; Trappe, T. A.; Thompson, J. L.; Costill, D. L.; Riley, D. A.; Fitts, R. H.

1997-01-01

The purpose of this study was to examine the effect of prolonged bed rest (BR) on the peak isometric force (P0) and unloaded shortening velocity (V0) of single Ca(2+)-activated muscle fibers. Soleus muscle biopsies were obtained from eight adult males before and after 17 days of 6 degrees head-down BR. Chemically permeabilized single fiber segments were mounted between a force transducer and position motor, activated with saturating levels of Ca2+, and subjected to slack length steps. V0 was determined by plotting the time for force redevelopment vs. the slack step distance. Gel electrophoresis revealed that 96% of the pre- and 87% of the post-BR fibers studied expressed only the slow type I myosin heavy chain isoform. Fibers with diameter > 100 microns made up only 14% of this post-BR type I population compared with 33% of the pre-BR type I population. Consequently, the post-BR type I fibers (n = 147) were, on average, 5% smaller in diameter than the pre-BR type I fibers (n = 218) and produced 13% less absolute P0. BR had no overall effect on P0 per fiber cross-sectional area (P0/CSA), even though half of the subjects displayed a decline of 9-12% in P0/CSA after BR. Type I fiber V0 increased by an average of 34% with BR. Although the ratio of myosin light chain 3 to myosin light chain 2 also rose with BR, there was no correlation between this ratio and V0 for either the pre- or post-BR fibers. In separate fibers obtained from the original biopsies, quantitative electron microscopy revealed a 20-24% decrease in thin filament density, with no change in thick filament density. These results raise the possibility that alterations in the geometric relationships between thin and thick filaments may be at least partially responsible for the elevated V0 of the post-BR type I fibers.

La Saturated Absorption Spectroscopy for Applications in Quantum Information

NASA Astrophysics Data System (ADS)

Becker, Patrick; Donoghue, Liz; Dungan, Kristina; Liu, Jackie; Olmschenk, Steven

2015-05-01

Quantum information may revolutionize computation and communication by utilizing quantum systems based on matter quantum bits and entangled light. Ions are excellent candidates for quantum bits as they can be well-isolated from unwanted external influences by trapping and laser cooling. Doubly-ionized lanthanum in particular shows promise for use in quantum information as it has infrared transitions in the telecom band, with low attenuation in standard optical fiber, potentially allowing for long distance information transfer. However, the hyperfine splittings of the lowest energy levels, required for laser cooling, have not been measured. We present progress and recent results towards measuring the hyperfine splittings of these levels in lanthanum by saturated absorption spectroscopy with a hollow cathode lamp. This research is supported by the Army Research Office, Research Corporation for Science Advancement, and Denison University.

In vitro photoacoustic measurement of hemoglobin oxygen saturation using a single pulsed broadband supercontinuum laser source.

PubMed

Lee, Changho; Jeon, Mansik; Jeon, Min Yong; Kim, Jeehyun; Kim, Chulhong

2014-06-20

We have utilized a single pulsed broadband supercontinuum laser source to photoacoustically sense total hemoglobin concentration (HbT) and oxygen saturation of hemoglobin (SO2) in bloods in vitro. Unlike existing expensive and bulky laser systems typically used for functional photoacoustic imaging (PAI), our laser system is relatively cost-effective and compact. Instead of using two single wavelengths, two wavelength bands were applied to distinguish the concentrations of two different chromophores in the mixture. In addition, we have successfully extracted the total dye concentration and the ratio of the red dye concentration to the total dye concentration in mixed red and blue dye solutions in phantoms. The results indicate that PAI with a cheap and compact fiber based laser source can potentially provide HbT and SO2 in live animals in vivo.

The effect of temperature and moisture on electrical resistance, strain sensitivity and crack sensitivity of steel fiber reinforced smart cement composite

NASA Astrophysics Data System (ADS)

Teomete, Egemen

2016-07-01

Earthquakes, material degradations and other environmental factors necessitate structural health monitoring (SHM). Metal foil strain gages used for SHM have low durability and low sensitivity. These factors motivated researchers to work on cement based strain sensors. In this study, the effects of temperature and moisture on electrical resistance, compressive and tensile strain gage factors (strain sensitivity) and crack sensitivity were determined for steel fiber reinforced cement based composite. A rapid increase of electrical resistance at 200 °C was observed due to damage occurring between cement paste, aggregates and steel fibers. The moisture—electrical resistance relationship was investigated. The specimens taken out of the cure were saturated with water and had a moisture content of 9.49%. The minimum electrical resistance was obtained at 9% moisture at which fiber-fiber and fiber-matrix contact was maximum and the water in micro voids was acting as an electrolyte, conducting electrons. The variation of compressive and tensile strain gage factors (strain sensitivities) and crack sensitivity were investigated by conducting compression, split tensile and notched bending tests with different moisture contents. The highest gage factor for the compression test was obtained at optimal moisture content, at which electrical resistance was minimum. The tensile strain gage factor for split tensile test and crack sensitivity increased by decreasing moisture content. The mechanisms between moisture content, electrical resistance, gage factors and crack sensitivity were elucidated. The relations of moisture content with electrical resistance, gage factors and crack sensitivities have been presented for the first time in this study for steel fiber reinforced cement based composites. The results are important for the development of self sensing cement based smart materials.

Diffuse reflectance spectra measured in vivo in human tissues during Photofrin-mediated pleural photodynamic therapy

NASA Astrophysics Data System (ADS)

Finlay, Jarod C.; Zhu, Timothy C.; Dimofte, Andreea; Friedberg, Joseph S.; Hahn, Stephen M.

2006-02-01

Optimal delivery of light in photodynamic therapy (PDT) requires not only optimal placement and power of light sources, but knowledge of the dynamics of light propagation in the tissue being treated and in the surrounding normal tissue, and of their respective accumulations of sensitizer. In an effort to quantify both tissue optical properties and sensitizer distribution, we have measured fluorescence emission and diffuse reflectance spectra at the surface of a variety of tissue types in the thoracic cavities of human patients. The patients studied here were enrolled in Phase II clinical trials of Photofrin-mediated PDT for the treatment of non-small cell lung cancer and cancers with pleural effusion. Patients were given Photofrin at dose of 2 mg per kg body weight 24 hours prior to treatment. Each patient received surgical resection of the affected lung and pleura. Patients received intracavity PDT at 630nm to a dose of 30 J/cm2, as determined by isotropic detectors sutured to the cavity walls. We measured the diffuse reflectance spectra before and after PDT in various positions within the cavity, including tumor, diaphragm, pericardium, skin, and chest wall muscle in 5 patients. The measurements we acquired using a specially designed fiber optic-based probe consisting of one fluorescence excitation fiber, one white light delivery fiber, and 9 detection fibers spaced at distances from 0.36 to 7.8 mm from the source, all of which are imaged via a spectrograph onto a CCD, allowing measurement of radially-resolved diffuse reflectance and fluorescence spectra. The light sources for these two measurements (a 403-nm diode laser and a halogen lamp, respectively) were blocked by computer-controlled shutters, allowing sequential fluorescence, reflectance, and background acquisition. The diffuse reflectance was analyzed to determine the absorption and scattering spectra of the tissue and from these, the concentration and oxygenation of hemoglobin and the local drug uptake. The total hemoglobin concentration in normal tissues varied from 50 to 300 µM, and the oxygen saturation was generally above 60%. One tumor measured exhibited higher hemoglobin concentration and lower saturation.

Major food sources of calories, added sugars, and saturated fat and their contribution to essential nutrient intakes in the U.S. diet: data from the National Health and Nutrition Examination Survey (2003-2006).

PubMed

Huth, Peter J; Fulgoni, Victor L; Keast, Debra R; Park, Keigan; Auestad, Nancy

2013-08-08

The risk of chronic disease cannot be predicted simply by the content of a single nutrient in a food or food group in the diet. The contribution of food sources of calories, added sugars and saturated fat (SFA) to intakes of dietary fiber and micronutrients of public health importance is also relevant to understanding the overall dietary impact of these foods. Identify the top food sources of calories, added sugars and SFA in the U.S. diet and quantify their contribution to fiber and micronutrient intakes. Single 24-hour dietary recalls (Day 1) collected from participants ≥2 years (n = 16,822) of the What We Eat in America, National Health and Nutrition Examination Survey (WWEIA/NHANES 2003-2006) were analyzed. All analyses included sample weights to account for the survey design. Calorie and nutrient intakes from foods included contributions from disaggregated food mixtures and tabulated by rank order. No one food category contributes more than 7.2% of calories to the overall U.S. diet, but half of the top 10 contribute 10% or more of total dietary fiber and micronutrients. Three of the top 10 sources of calories and SFA (beef, milk and cheese) contribute 46.3% of the calcium, 49.5% of the vitamin D, 42.3% of the vitamin B12 as well as other essential nutrients to the American diet. On the other hand, foods categorized as desserts, snacks, or beverages, contribute 13.6% of total calories, 83% of added sugar intake, and provide little or no nutritional value. Including food components of disaggregated recipes more accurately estimated the contribution of foods like beef, milk or cheese to overall nutrient intake compared to "as consumed" food categorizations. Some food sources of calories, added sugars and SFA make major contributions to American dietary fiber and micronutrient intakes. Dietary modifications targeting reductions in calories, added sugar, or SFA need to take these key micronutrient sources into account so as not to have the unintended consequence of lowering overall dietary quality.

Hypertrophic Cardiomyopathy Cardiac Troponin C Mutations Differentially Affect Slow Skeletal and Cardiac Muscle Regulation

PubMed Central

Veltri, Tiago; Landim-Vieira, Maicon; Parvatiyar, Michelle S.; Gonzalez-Martinez, David; Dieseldorff Jones, Karissa M.; Michell, Clara A.; Dweck, David; Landstrom, Andrew P.; Chase, P. Bryant; Pinto, Jose R.

2017-01-01

Mutations in TNNC1—the gene encoding cardiac troponin C (cTnC)—that have been associated with hypertrophic cardiomyopathy (HCM) and cardiac dysfunction may also affect Ca2+-regulation and function of slow skeletal muscle since the same gene is expressed in both cardiac and slow skeletal muscle. Therefore, we reconstituted rabbit soleus fibers and bovine masseter myofibrils with mutant cTnCs (A8V, C84Y, E134D, and D145E) associated with HCM to investigate their effects on contractile force and ATPase rates, respectively. Previously, we showed that these HCM cTnC mutants, except for E134D, increased the Ca2+ sensitivity of force development in cardiac preparations. In the current study, an increase in Ca2+ sensitivity of isometric force was only observed for the C84Y mutant when reconstituted in soleus fibers. Incorporation of cTnC C84Y in bovine masseter myofibrils reduced the ATPase activity at saturating [Ca2+], whereas, incorporation of cTnC D145E increased the ATPase activity at inhibiting and saturating [Ca2+]. We also tested whether reconstitution of cardiac fibers with troponin complexes containing the cTnC mutants and slow skeletal troponin I (ssTnI) could emulate the slow skeletal functional phenotype. Reconstitution of cardiac fibers with troponin complexes containing ssTnI attenuated the Ca2+ sensitization of isometric force when cTnC A8V and D145E were present; however, it was enhanced for C84Y. In summary, although the A8V and D145E mutants are present in both muscle types, their functional phenotype is more prominent in cardiac muscle than in slow skeletal muscle, which has implications for the protein-protein interactions within the troponin complex. The C84Y mutant warrants further investigation since it drastically alters the properties of both muscle types and may account for the earlier clinical onset in the proband. PMID:28473771

A Comparison of Concentrations of Sodium and Related Nutrients (Potassium, Total Dietary Fiber, Total and Saturated Fat, and Total Sugar) in Private-Label and National Brands of Popular, Sodium-Contributing, Commercially Pack

USDA-ARS?s Scientific Manuscript database

Private-label brands account for about one in four foods sold in U.S. supermarkets. They provide value to consumers due to their low cost. We know of no U.S. studies comparing the nutrition content of private-label with corresponding national-brand products. The objective of this study was to compar...

A very-low-fat vegan diet increases intake of protective dietary factors and decreases intake of pathogenic dietary factors.

PubMed

Dewell, Antonella; Weidner, Gerdi; Sumner, Michael D; Chi, Christine S; Ornish, Dean

2008-02-01

There is increasing evidence that dietary factors in plant-based diets are important in the prevention of chronic disease. This study examined protective (eg, antioxidant vitamins, carotenoids, and fiber) and pathogenic (eg, saturated fatty acids and cholesterol) dietary factors in a very-low-fat vegan diet. Ninety-three early-stage prostate cancer patients participated in a randomized controlled trial and were assigned to a very-low-fat (10% fat) vegan diet supplemented with soy protein and lifestyle changes or to usual care. Three-day food records were collected at baseline (n=42 intervention, n=43 control) and after 1 year (n=37 in each group). Analyses of changes in dietary intake of macronutrients, vitamins, minerals, carotenoids, and isoflavones from baseline to 1 year showed significantly increased intake of most protective dietary factors (eg, fiber increased from a mean of 31 to 59 g/day, lycopene increased from 8,693 to 34,464 mug/day) and significantly decreased intake of most pathogenic dietary factors (eg, saturated fatty acids decreased from 20 to 5 g/day, cholesterol decreased from 200 to 10 mg/day) in the intervention group compared to controls. These results suggest that a very-low-fat vegan diet can be useful in increasing intake of protective nutrients and phytochemicals and minimizing intake of dietary factors implicated in several chronic diseases.

Fiber type- and fatty acid composition-dependent effects of high-fat diets on rat muscle triacylglyceride and fatty acid transporter protein-1 content.

PubMed

Marotta, Mario; Ferrer-Martnez, Andreu; Parnau, Josep; Turini, Marco; Macé, Katherine; Gómez Foix, Anna M

2004-08-01

Intramuscular triacylglyceride (TAG) is considered an independent marker of insulin resistance in humans. Here, we examined the effect of high-fat diets, based on distinct fatty acid compositions (saturated, monounsaturated or n-6 polyunsaturated), on TAG levels and fatty acid transporter protein (FATP-1) expression in 2 rat muscles that differ in their fiber type, soleus, and gastrocnemius; the relationship to whole body glucose intolerance was also studied. Compared with carbohydrate-fed rats, the groups subjected to any one of the high-fat diets consistently exhibited enhanced body weight gain and adiposity, elevated plasma free fatty acids and TAG in the fed condition, hyperinsulinemia, and glucose intolerance. TAG content was consistently higher in soleus than in gastrocnemius, but was only significantly elevated by the n-6 polyunsaturated-based diet. FATP-1 levels in soleus were double those in gastrocnemius muscle in carbohydrate-fed animals. High-fat diets caused an elevation in FATP-1 protein content in soleus, but a reduction in gastrocnemius. In conclusion, the hyperinsulinemic hyperlipidemic condition upregulates FATP-1 expression in soleus and downregulates that of gastrocnemius. Hypercaloric saturated, monounsaturated, or n-6 polyunsaturated lipid diets cause equivalent whole body insulin resistance in rats, but only an n-6 polyunsaturated acid-based diet triggers intramuscular TAG accumulation. Copyright 2004 Elsevier Inc.

Diet and serum lipids in vegan vegetarians: a model for risk reduction.

PubMed

Resnicow, K; Barone, J; Engle, A; Miller, S; Haley, N J; Fleming, D; Wynder, E

1991-04-01

The lipid levels and dietary habits of 31 Seventh-Day Adventist vegan vegetarians (aged 5 to 46 years) who consume no animal products were assessed. Mean serum total cholesterol (3.4 mmol/L), low-density-lipoprotein cholesterol (1.8 mmol/L), and triglyceride (0.8 mmol/L) levels were lower than expected values derived from the Lipid Research Clinics Population Studies prevalence data. Mean high-density-lipoprotein cholesterol (1.3 mmol/L) was comparable to expected values. Analysis of quantitative food frequency data showed that vegans had a significantly lower daily intake of total energy, percentage of energy from fat (31% vs 38%), total fat, saturated fat, monounsaturated fatty acids, cholesterol, and protein and a significantly higher intake of fiber than a sample of matched omnivore controls. Vegans' food intake was also compared with expected values, matched for sex and age, derived from the second National Health and Nutrition Examination Survey and Continuing Survey of Food Intakes by Individuals 24-hour recall data. The vegan diet was characterized by increased consumption of almonds, cashews, and their nut butters; dried fruits; citrus fruits; soy milk; and greens. We conclude from the present study that a strict vegan diet, which is typically very low in saturated fat and dietary cholesterol and high in fiber, can help children and adults maintain or achieve desirable blood lipid levels.

Consumption of whole-grain cereals during weight loss: effects on dietary quality, dietary fiber, magnesium, vitamin B-6, and obesity.

PubMed

Melanson, Kathleen J; Angelopoulos, Theodore J; Nguyen, Von T; Martini, Margaret; Zukley, Linda; Lowndes, Joshua; Dube, Thomas J; Fiutem, Justin J; Yount, Byron W; Rippe, James M

2006-09-01

While various weight-management approaches produce weight loss, they may differ in dietary quality. We monitored changes in nutrient intakes in overweight and obese subjects on three different weight-management programs. Randomized clinical trial (pilot study) with two 12-week phases: phase 1, weekly counseling; phase 2, monitoring only. One hundred eighty nonsmoking, sedentary overweight and obese adults began this outpatient study; 134 (body mass index [calculated as kg/m(2)]=30.9+/-2.4; age=42.3+/-1.2 years) were used in analyses. Twenty-four weeks of exercise only (control group), hypocaloric diet plus exercise, or hypocaloric diet with fiber-rich whole-grain cereals plus exercise. At weeks 0, 12, and 24, diet quality was assessed by 3-day food records and body weight was measured. Three-way analysis of variance with repeated measures. The hypocaloric diet with fiber-rich whole-grain cereals plus exercise decreased energy intake more than exercise only (P=0.032). By week 12, the hypocaloric diet with fiber-rich whole-grain cereals plus exercise and the hypocaloric diet plus exercise decreased total fat more than exercise only, which was sustained in the hypocaloric diet with fiber-rich whole-grain cereals plus exercise at 24 weeks (P<0.001). At weeks 12 and 24, the hypocaloric diet with fiber-rich whole-grain cereals plus exercise reduced saturated fat intake more than exercise only. The hypocaloric diet with fiber-rich whole-grain cereals plus exercise increased total fiber, insoluble fiber (both P<0.001), magnesium (P=0.004), and vitamin B-6 (P=0.002) intakes more than the hypocaloric diet plus exercise and exercise only. Calcium and vitamin E intakes were inadequate in all groups. Weight loss was similar in the hypocaloric diet with fiber-rich whole-grain cereals plus exercise and the hypocaloric diet plus exercise. Weight-reduction strategies may be associated with reduced intake of micronutrients, such as calcium and vitamin E. However, a hypocaloric diet with fiber-rich whole-grain cereal is effective for improving or maintaining other aspects of dietary quality during weight loss.

Proteomic Analysis of Lipid Raft-Like Detergent-Resistant Membranes of Lens Fiber Cells.

PubMed

Wang, Zhen; Schey, Kevin L

2015-12-01

Plasma membranes of lens fiber cells have high levels of long-chain saturated fatty acids, cholesterol, and sphingolipids-key components of lipid rafts. Thus, lipid rafts are expected to constitute a significant portion of fiber cell membranes and play important roles in lens biology. The purpose of this study was to characterize the lens lipid raft proteome. Quantitative proteomics, both label-free and iTRAQ methods, were used to characterize lens fiber cell lipid raft proteins. Detergent-resistant, lipid raft membrane (DRM) fractions were isolated by sucrose gradient centrifugation. To confirm protein localization to lipid rafts, protein sensitivity to cholesterol removal by methyl-β-cyclodextrin was quantified by iTRAQ analysis. A total of 506 proteins were identified in raft-like detergent-resistant membranes. Proteins identified support important functions of raft domains in fiber cells, including trafficking, signal transduction, and cytoskeletal organization. In cholesterol-sensitivity studies, 200 proteins were quantified and 71 proteins were strongly affected by cholesterol removal. Lipid raft markers flotillin-1 and flotillin-2 and a significant fraction of AQP0, MP20, and AQP5 were found in the DRM fraction and were highly sensitive to cholesterol removal. Connexins 46 and 50 were more abundant in nonraft fractions, but a small fraction of each was found in the DRM fraction and was strongly affected by cholesterol removal. Quantification of modified AQP0 confirmed that fatty acylation targeted this protein to membrane raft domains. These data represent the first comprehensive profile of the lipid raft proteome of lens fiber cells and provide information on membrane protein organization in these cells.

Experimental investigation of high power pulsed 2.8 μm Er3+-doped ZBLAN fiber lasers

NASA Astrophysics Data System (ADS)

Shen, Yanlong; Wang, Yishan; Huang, Ke; Luan, Kunpeng; Chen, Hongwei; Tao, Mengmeng; Yu, Li; Yi, Aiping; Si, Jinhai

2017-05-01

We report on the recent progress on high power pulsed 2.8 μm Er3+-doped ZBLAN fiber laser through techniques of passively and actively Q-switching in our research group. In passively Q-switched operation, a diode-cladding-pumped mid-infrared passively Q-switched Er3+-doped ZBLAN fiber laser with an average output power of watt-level based on a semiconductor saturable absorber mirror (SESAM) was demonstrated. Stable pulse train was produced at a slope efficient of 17.8% with respect to launched pump power. The maximum average power of 1.01 W at a repetition rate of 146.3 kHz was achieved with a corresponding pulse energy of 6.9 μJ. The maximum peak power was calculated to be 21.9 W. In actively Q-switched operation, a diode-pumped actively Q-switched Er3+-doped ZBLAN fiber laser at 2.8 μm with an optical chopper was reported. The maximum laser pulse energy of up to 130 μJ and a pulse width of 127.3 ns at a repetition rate of 10 kHz with an operating wavelength of 2.78 μm was obtained, yielding the maximum peak power of exceeding 1.1 kW.

Graphene based widely-tunable and singly-polarized pulse generation with random fiber lasers

PubMed Central

Yao, B. C.; Rao, Y. J.; Wang, Z. N.; Wu, Y.; Zhou, J. H.; Wu, H.; Fan, M. Q.; Cao, X. L.; Zhang, W. L.; Chen, Y. F.; Li, Y. R.; Churkin, D.; Turitsyn, S.; Wong, C. W.

2015-01-01

Pulse generation often requires a stabilized cavity and its corresponding mode structure for initial phase-locking. Contrastingly, modeless cavity-free random lasers provide new possibilities for high quantum efficiency lasing that could potentially be widely tunable spectrally and temporally. Pulse generation in random lasers, however, has remained elusive since the discovery of modeless gain lasing. Here we report coherent pulse generation with modeless random lasers based on the unique polarization selectivity and broadband saturable absorption of monolayer graphene. Simultaneous temporal compression of cavity-free pulses are observed with such a polarization modulation, along with a broadly-tunable pulsewidth across two orders of magnitude down to 900 ps, a broadly-tunable repetition rate across three orders of magnitude up to 3 MHz, and a singly-polarized pulse train at 41 dB extinction ratio, about an order of magnitude larger than conventional pulsed fiber lasers. Moreover, our graphene-based pulse formation also demonstrates robust pulse-to-pulse stability and wide-wavelength operation due to the cavity-less feature. Such a graphene-based architecture not only provides a tunable pulsed random laser for fiber-optic sensing, speckle-free imaging, and laser-material processing, but also a new way for the non-random CW fiber lasers to generate widely tunable and singly-polarized pulses. PMID:26687730

Graphene based widely-tunable and singly-polarized pulse generation with random fiber lasers.

PubMed

Yao, B C; Rao, Y J; Wang, Z N; Wu, Y; Zhou, J H; Wu, H; Fan, M Q; Cao, X L; Zhang, W L; Chen, Y F; Li, Y R; Churkin, D; Turitsyn, S; Wong, C W

2015-12-21

Pulse generation often requires a stabilized cavity and its corresponding mode structure for initial phase-locking. Contrastingly, modeless cavity-free random lasers provide new possibilities for high quantum efficiency lasing that could potentially be widely tunable spectrally and temporally. Pulse generation in random lasers, however, has remained elusive since the discovery of modeless gain lasing. Here we report coherent pulse generation with modeless random lasers based on the unique polarization selectivity and broadband saturable absorption of monolayer graphene. Simultaneous temporal compression of cavity-free pulses are observed with such a polarization modulation, along with a broadly-tunable pulsewidth across two orders of magnitude down to 900 ps, a broadly-tunable repetition rate across three orders of magnitude up to 3 MHz, and a singly-polarized pulse train at 41 dB extinction ratio, about an order of magnitude larger than conventional pulsed fiber lasers. Moreover, our graphene-based pulse formation also demonstrates robust pulse-to-pulse stability and wide-wavelength operation due to the cavity-less feature. Such a graphene-based architecture not only provides a tunable pulsed random laser for fiber-optic sensing, speckle-free imaging, and laser-material processing, but also a new way for the non-random CW fiber lasers to generate widely tunable and singly-polarized pulses.

Switchable thulium-doped fiber laser from polarization rotation vector to scalar soliton

NASA Astrophysics Data System (ADS)

Wu, Zhichao; Fu, Songnian; Jiang, Kai; Song, Jue; Li, Huizi; Tang, Ming; Shum, Ping; Liu, Deming

2016-10-01

We experimentally demonstrate switchable temporal soliton generation from a thulium-doped fiber laser (TDFL), using carbon nanotubes as the mode-locker. With the help of residual polarization dependent loss of a wavelength division multiplexer, a weak nonlinear polarization rotation (NPR) effect can be achieved within the laser cavity, which may provide joint contribution for passive mode-locking operation. By finely adjusting the polarization to alter the strength of NPR-based saturable absorption, the TDFL either approaches the operation regime of scalar soliton with strong NPR effect, or generates polarization rotation locked vector soliton (PRLVS) with weak NPR effect. The scalar solitons and PRLVSs possess 3-dB optical spectrum bandwidth of 2.2 nm and 2 nm, pulse-width of 1.8 ps and 2 ps, respectively. Moreover, the PRLVSs demonstrate a typical energy exchange between two polarized components on optical spectra and a period-doubling feature in time domain. Such operation principle can also be used in 1550 nm band fiber lasers and other nonlinear systems.

Switchable thulium-doped fiber laser from polarization rotation vector to scalar soliton

PubMed Central

Wu, Zhichao; Fu, Songnian; Jiang, Kai; Song, Jue; Li, Huizi; Tang, Ming; Shum, Ping; Liu, Deming

2016-01-01

We experimentally demonstrate switchable temporal soliton generation from a thulium-doped fiber laser (TDFL), using carbon nanotubes as the mode-locker. With the help of residual polarization dependent loss of a wavelength division multiplexer, a weak nonlinear polarization rotation (NPR) effect can be achieved within the laser cavity, which may provide joint contribution for passive mode-locking operation. By finely adjusting the polarization to alter the strength of NPR-based saturable absorption, the TDFL either approaches the operation regime of scalar soliton with strong NPR effect, or generates polarization rotation locked vector soliton (PRLVS) with weak NPR effect. The scalar solitons and PRLVSs possess 3-dB optical spectrum bandwidth of 2.2 nm and 2 nm, pulse-width of 1.8 ps and 2 ps, respectively. Moreover, the PRLVSs demonstrate a typical energy exchange between two polarized components on optical spectra and a period-doubling feature in time domain. Such operation principle can also be used in 1550 nm band fiber lasers and other nonlinear systems. PMID:27708427

Switchable thulium-doped fiber laser from polarization rotation vector to scalar soliton.

PubMed

Wu, Zhichao; Fu, Songnian; Jiang, Kai; Song, Jue; Li, Huizi; Tang, Ming; Shum, Ping; Liu, Deming

2016-10-06

We experimentally demonstrate switchable temporal soliton generation from a thulium-doped fiber laser (TDFL), using carbon nanotubes as the mode-locker. With the help of residual polarization dependent loss of a wavelength division multiplexer, a weak nonlinear polarization rotation (NPR) effect can be achieved within the laser cavity, which may provide joint contribution for passive mode-locking operation. By finely adjusting the polarization to alter the strength of NPR-based saturable absorption, the TDFL either approaches the operation regime of scalar soliton with strong NPR effect, or generates polarization rotation locked vector soliton (PRLVS) with weak NPR effect. The scalar solitons and PRLVSs possess 3-dB optical spectrum bandwidth of 2.2 nm and 2 nm, pulse-width of 1.8 ps and 2 ps, respectively. Moreover, the PRLVSs demonstrate a typical energy exchange between two polarized components on optical spectra and a period-doubling feature in time domain. Such operation principle can also be used in 1550 nm band fiber lasers and other nonlinear systems.

Design and characterization of a novel multimodal fiber-optic probe and spectroscopy system for skin cancer applications

PubMed Central

Sharma, Manu; Marple, Eric; Reichenberg, Jason; Tunnell, James W.

2014-01-01

The design and characterization of an instrument combining Raman, fluorescence, and reflectance spectroscopic modalities is presented. Instrument development has targeted skin cancer applications as a novel fiber-optic probe has been specially designed to interrogate cutaneous lesions. The instrument is modular and both its software and hardware components are described in depth. Characterization of the fiber-optic probe is also presented, which details the probe's ability to measure diagnostically important parameters such as intrinsic fluorescence and absorption and reduced scattering coefficients along with critical performance metrics such as high Raman signal-to-noise ratios at clinically practical exposure times. Validation results using liquid phantoms show that the probe and system can extract absorption and scattering coefficients with less than 10% error. As the goal is to use the instrument for the clinical early detection of skin cancer, preliminary clinical data are also presented, which indicates our system's ability to measure physiological quantities such as relative collagen and nicotinamide adenine dinucleotide concentration, oxygen saturation, blood volume fraction, and mean vessel diameter. PMID:25173240

Pure antimony film as saturable absorber for Q-switched erbium-doped fiber laser

NASA Astrophysics Data System (ADS)

Rahman, M. F. A.; Zhalilah, M. Z.; Latiff, A. A.; Rosol, A. H. A.; Lokman, M. Q.; Bushroa, A. R.; Dimyati, K.; Harun, S. W.

2018-04-01

This paper reports on the use of Antimony (Sb) polymer film to generate stable Q-switching pulses in Erbium-doped fiber laser (EDFL) cavity. The SA is fabricated by coating a thin layer of Sb on a polyvinyl alcohol (PVA) film through physical vapour deposition (PVD) process. A 1 × 1 mm area of the film SA is cut and integrated into between two fiber ferrules inside the laser cavity for intra-cavity loss modulation. Self-starting and stable Q-switched pulses are obtained within a pump power range from 60 to 142 mW. Within this range, the repetition rate increases from 70.82 to 98.04 kHz, while pulse width decreases from 7.42 to 5.36 μs. The fundamental frequency signal-to-noise ratio of the pulse signal is 74 dB, which indicates the excellent stability of the pulses. The maximum output power and pulse energy are 8.45 mW and 86.19 nJ, respectively. Our demonstration shows that Sb film SA capable of generating stable pulses train operating at 1.55-micron region.

Fiber networks amplify active stress

NASA Astrophysics Data System (ADS)

Lenz, Martin; Ronceray, Pierre; Broedersz, Chase

Large-scale force generation is essential for biological functions such as cell motility, embryonic development, and muscle contraction. In these processes, forces generated at the molecular level by motor proteins are transmitted by disordered fiber networks, resulting in large-scale active stresses. While fiber networks are well characterized macroscopically, this stress generation by microscopic active units is not well understood. I will present a comprehensive theoretical study of force transmission in these networks. I will show that the linear, small-force response of the networks is remarkably simple, as the macroscopic active stress depends only on the geometry of the force-exerting unit. In contrast, as non-linear buckling occurs around these units, local active forces are rectified towards isotropic contraction and strongly amplified. This stress amplification is reinforced by the networks' disordered nature, but saturates for high densities of active units. I will show that our predictions are quantitatively consistent with experiments on reconstituted tissues and actomyosin networks, and that they shed light on the role of the network microstructure in shaping active stresses in cells and tissue.

Chromium doped nano-phase separated yttria-alumina-silica glass based optical fiber preform: fabrication and characterization

NASA Astrophysics Data System (ADS)

Dutta, Debjit; Dhar, Anirban; Das, Shyamal; Bysakh, Sandip; Kir'yanov, Alexandar; Paul, Mukul Chandra

2015-06-01

Transition metal (TM) doping in silica core optical fiber is one of the research area which has been studied for long time and Chromium (Cr) doping specially attracts a lot of research interest due to their broad emission band covering U, C and L band with many potential application such as saturable absorber or broadband amplifier etc. This paper present fabrication of Cr doped nano-phase separated silica fiber within yttria-alumina-silica core glass through conventional Modified Chemical Vapor Deposition (MCVD) process coupled with solution doping technique along with different material and optical characterization. For the first time scanning electron microscope (SEM) / energy dispersive X-ray (EDX) analysis of porous soot sample and final preform has been utilized to investigate incorporation mechanism of Crions with special emphasis on Cr-species evaporation at different stages of fabrication. We also report that optimized annealing condition of our fabricated preform exhibited enhanced fluorescence emission and a broad band within 550- 800 nm wavelength region under pumping at 532 nm wavelength due to nano-phase restructuration.

Slow and fast light via SBS in optical fibers for short pulses and broadband pump

NASA Astrophysics Data System (ADS)

Kalosha, V. P.; Chen, Liang; Bao, Xiaoyi

2006-12-01

Slow-light effect via stimulated Brillouin scattering (SBS) in single-mode optical fibers was considered for short probe pulses of nanosecond duration relevant to Gb/s data streams. Unlike recent estimations of delay versus pump based on steady-state small-signal approximation we have used numerical solution of three-wave equations describing SBS for a realistic fiber length. Both regimes of small signal and pump depletion (gain saturation) were considered. The physical origin of Stokes pulse distortion is revealed which is related to excitation of long-living acoustic field behind the pulse and prevents effective delay control by pump power increase at cw pumping. We have shown different slope of the gain-dependent delay for different pulse durations. Spectrally broadened pumping by multiple cw components, frequency-modulated pump and pulse train were studied for short pulses which allow to obtain large delay and suppress pulse distortion. In the pump-depletion regime of pumping by pulse train, both pulse delay and distortion decrease with increasing pump, and the pulse achieves advancement.

Detecting Damage in Ceramic Matrix Composites Using Electrical Resistance

NASA Technical Reports Server (NTRS)

Smith, Craig E.; Gyekenyesi, Andrew

2011-01-01

The majority of damage in SiC/SiC ceramic matrix composites subjected to monotonic tensile loads is in the form of distributed matrix cracks. These cracks initiate near stress concentrations, such as 90 deg fiber tows or large matrix pores and continue to accumulate with additional stress until matrix crack saturation is achieved. Such damage is difficult to detect with conventional nondestructive evaluation techniques (immersion ultrasonics, x-ray, etc.). Monitoring a specimen.s electrical resistance change provides an indirect approach for monitoring matrix crack density. Sylramic-iBN fiber- reinforced SiC composites with a melt infiltrated (MI) matrix were tensile tested at room temperature. Results showed an increase in resistance of more than 500% prior to fracture, which can be detected either in situ or post-damage. A relationship between resistance change and matrix crack density was also determined.

Detecting Cracks in Ceramic Matrix Composites by Electrical Resistance

NASA Technical Reports Server (NTRS)

Smith, Craig; Gyekenyesi, Andrew

2011-01-01

The majority of damage in SiC/SiC ceramic matrix composites subjected to monotonic tensile loads is in the form of distributed matrix cracks. These cracks initiate near stress concentrations, such as 90o fiber tows or large matrix pores and continue to accumulate with additional stress until matrix crack saturation is achieved. Such damage is difficult to detect with conventional nondestructive evaluation techniques (immersion ultrasonics, x-ray, etc.). Monitoring a specimen.s electrical resistance change provides an indirect approach for monitoring matrix crack density. Sylramic-iBN fiber- reinforced SiC composites with a melt infiltrated (MI) matrix were tensile tested at room temperature. Results showed an increase in resistance of more than 500% prior to fracture, which can be detected either in situ or post-damage. A relationship between resistance change and matrix crack density was also determined.

Noninvasive photoacoustic measurement of absorption coefficient using internal light irradiation of cylindrical diffusing fiber

NASA Astrophysics Data System (ADS)

Peng, Dong-qing; Zhu, Li-li; Li, Zhi-fang; Li, Hui

2017-09-01

Absorption coefficient of biological tissue is an important parameter in biomedicine, but its determination remains a challenge. In this paper, we propose a method using focusing photoacoustic imaging technique and internal light irradiation of cylindrical diffusing fiber (CDF) to quantify the target optical absorption coefficient. Absorption coefficients for ink absorbers are firstly determined through photoacoustic and spectrophotometric measurements at the same excitation, which demonstrates the feasibility of this method. Also, the optical absorption coefficients of ink absorbers with several concentrations are measured. Finally, the two-dimensional scanning photoacoustic image is obtained. Optical absorption coefficient measurement and simultaneous photoacoustic imaging of absorber non-invasively are the typical characteristics of the method. This method can play a significant role for non-invasive determination of blood oxygen saturation, the absorption-based imaging and therapy.

Dependence of diameters and oxygen saturation of retinal vessels on visual field damage and age in primary open-angle glaucoma.

PubMed

Ramm, Lisa; Jentsch, Susanne; Peters, Sven; Sauer, Lydia; Augsten, Regine; Hammer, Martin

2016-05-01

To investigate the interrelationship between the oxygen supply of the retina and its regulation with the severity of primary open-angle glaucoma (POAG). Central retinal artery (CRAE) and vein (CRVE) diameters and oxygen saturation of peripapillary retinal vessels in 41 patients suffering from POAG (64.1 ± 12.9 years) and 40 healthy volunteers (63.6 ± 14.1 years) were measured using the retinal vessel analyzer. All measures were taken before and during flicker light stimulation. The mean retinal nerve fiber layer thickness (RNFLT) was determined by OCT and the visual field mean defect (MD) was identified using perimetry. In glaucoma patients, CRAE (r = -0.48 p = 0.002) and CRVE (r = -0.394 p = 0.014) at baseline were inversely related to MD, while arterial and venous oxygen saturation showed no significant dependence on the severity of the damage. However, the flicker light-induced change in arterio-venous difference in oxygen saturation was correlated with the MD (r = 0.358 p = 0.027). The diameters of arteries and veins at baseline decreased with reduction of the mean RNFLT (arteries: r = 0.718 p < 0.001; veins: r = 0.685 p < 0.001). Vessel diameters showed a strong correlation with RNFLT and MD. This, as well as the reduction of stimulation-induced change in arterio-venous oxygen saturation difference with visual field loss, may be explained by a reduction of the retinal metabolic demand with progressive loss of neuronal tissue in glaucoma. © 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Regime dependence of photo-darkening-induced modal degradation in high power fiber amplifier (Conference Presentation)

NASA Astrophysics Data System (ADS)

Boullet, Johan; Vincont, Cyril; Jolly, Alain; Pierre, Christophe

2017-03-01

Thermally induced transverse modal instabilities (TMI) have attracted these five years an intense research efforts of the entire fiber laser development community, as it represents the current most limiting effect of further power scaling of high power fiber laser. Anyway, since 2014, a few publications point out a new limiting thermal effect: fiber modal degradation (FMD). It is characterized by a power rollover and simultaneous increase of the cladding light at an average power far from the TMI threshold together with a degraded beam which does not exhibit temporal fluctuations, which is one of the main characteristic of TMI. We report here on the first systemic experimental study of FMD in a high power photonic crystal fiber. We put a particular emphasis on the dependence of its average power threshold on the regime of operation. We experimentally demonstrate that this dependence is intrinsically linked to regime-dependent PD-saturated losses, which are nearly three times higher in CW regime than in short pulse picosecond regime. We make the hypothesis that the existence of these different PD equilibrium states between CW regime and picosecond QCW pulsed regime is due to a partial photo-bleaching of color centers in picosecond regime thanks to a higher probability of multi-photon process induced photobleaching (PB) at high peak power. This hypothesis is corroborated by the demonstration of the reversibility of the FMD induced in CW regime by simply switching the seed CW 1064 nm light by a short pulse, picosecond oscillator.

Multi-mJ energy extraction using Yb-fiber based coherent pulse stacking amplification of fs pulses (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ruppe, John M.; Pei, Hanzhang; Chen, Siyun; Sheikhsofla, Morteza; Wilcox, Russell B.; Nees, John A.; Galvanauskas, Almantas

2017-03-01

We report multi-mJ energy (>5mJ) extraction from femtosecond-pulse Yb-doped fiber CPA using coherent pulse stacking amplification (CPSA) technique. This high energy extraction has been enabled by amplifying 10's of nanosecond long pulse sequence, and by using 85-µm core Yb-doped CCC fiber based power amplification stage. The CPSA system consists of 1-GHz repetition rate mode-locked fiber oscillator, followed by a pair of fast phase and amplitude electro-optic modulators, a diffraction-grating based pulse stretcher, a fiber amplifier chain, a GTI-cavity based pulse stacker, and a diffraction grating pulse compressor. Electro-optic modulators are used to carve out from the 1-GHz mode-locked pulse train an amplitude and phase modulated pulse burst, which after stretching and amplification, becomes equal-amplitude pulse burst consisting of 27 stretched pulses, each approximately 1-ns long. Initial pulse-burst shaping accounts for the strong amplifier saturation effects, so that it is compensated at the power amplifier output. This 27-pulse burst is then coherently stacked into a single pulse using a multiplexed sequence of 5 GTI cavities. The compact-footprint 4+1 multiplexed pulse stacker consists of 4 cavities having rountrip of 1 ns, and one Herriott-cell folded cavity - with 9ns roundtrip. After stacking, stretched pulses are compressed down to the bandwidth-limited 300 fs duration using a standard diffraction-grating pulse compressor.

Effects of carbohydrate type or bicarbonate addition to grass silage-based diets on enteric methane emissions and milk fatty acid composition in dairy cows.

PubMed

Bougouin, A; Ferlay, A; Doreau, M; Martin, C

2018-04-18

The aim of the study was to compare the effect of fiber- or starch-rich diets based on grass silage, supplemented or not with bicarbonate, on CH 4 emissions and milk fatty acid (FA) profile in dairy cows. The experiment was conducted as a 4 × 4 Latin square design with a 2 × 2 factorial arrangement: carbohydrate type [starch- or fiber-rich diets with dietary starch level of 23.1 and 5.9% on a dry matter basis, respectively], without or with bicarbonate addition [0 and 1% of the dry matter intake, respectively]. Four multiparous lactating Holstein cows were fed 4 diets with 42% grass silage, 8% hay, and 50% concentrate in 4 consecutive 4-wk periods: (1) starch-rich diet, (2) starch-rich diet with bicarbonate, (3) fiber-rich diet, and (4) fiber-rich diet with bicarbonate. Intake and milk production were measured daily and milk composition was measured weekly; CH 4 emission and total-tract digestibility were measured simultaneously (5 d, wk 4) when animals were in open-circuit respiration chambers. Sensors continuously monitored rumen pH (3 d, wk 4), and fermentation parameters were analyzed from rumen fluid samples taken before feeding (1 d, wk 3). Cows fed starch-rich diets had less CH 4 emissions (on average, -18% in g/d; -15% in g/kg of dry matter intake; -19% in g/kg of milk) compared with fiber-rich diets. Carbohydrate type did not affect digestion of nutrients, except starch, which increased with starch-rich diets. The decrease in rumen protozoa number (-36%) and the shift in rumen fermentation toward propionate at the expense of butyrate for cows fed the starch-rich diets may be the main factor in reducing CH 4 emissions. Milk of cows fed starch-rich diets had lower concentrations in trans-11 C18:1, sum of cis-C18, cis-9,trans-11 conjugated linoleic acid (CLA), and sum of CLA, along with greater concentration of some minor isomers of CLA and saturated FA in comparison to the fiber-rich diet. Bicarbonate addition did not influence CH 4 emissions or nutrient digestibility regardless of the carbohydrate type in the diet. Rumen pH increased with bicarbonate addition, whereas other rumen parameters and milk FA composition were almost comparable between diets. Feeding dairy cows a starch-rich diet based on grass silage helps to limit the negative environmental effect of ruminants, but does not lead to greater milk nutritional value because milk saturated FA content is increased. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Method of making a high performance ultracapacitor

DOEpatents

Farahmandi, C. Joseph; Dispennette, John M.

2000-07-26

A high performance double layer capacitor having an electric double layer formed in the interface between activated carbon and an electrolyte is disclosed. The high performance double layer capacitor includes a pair of aluminum impregnated carbon composite electrodes having an evenly distributed and continuous path of aluminum impregnated within an activated carbon fiber preform saturated with a high performance electrolytic solution. The high performance double layer capacitor is capable of delivering at least 5 Wh/kg of useful energy at power ratings of at least 600 W/kg.

Aluminum-carbon composite electrode

DOEpatents

Farahmandi, C. Joseph; Dispennette, John M.

1998-07-07

A high performance double layer capacitor having an electric double layer formed in the interface between activated carbon and an electrolyte is disclosed. The high performance double layer capacitor includes a pair of aluminum impregnated carbon composite electrodes having an evenly distributed and continuous path of aluminum impregnated within an activated carbon fiber preform saturated with a high performance electrolytic solution. The high performance double layer capacitor is capable of delivering at least 5 Wh/kg of useful energy at power ratings of at least 600 W/kg.

Aluminum-carbon composite electrode

DOEpatents

Farahmandi, C.J.; Dispennette, J.M.

1998-07-07

A high performance double layer capacitor having an electric double layer formed in the interface between activated carbon and an electrolyte is disclosed. The high performance double layer capacitor includes a pair of aluminum impregnated carbon composite electrodes having an evenly distributed and continuous path of aluminum impregnated within an activated carbon fiber preform saturated with a high performance electrolytic solution. The high performance double layer capacitor is capable of delivering at least 5 Wh/kg of useful energy at power ratings of at least 600 W/kg. 3 figs.

An Intrinsic Fiber-Optic Sensor for Structure Lightning Current Measurement

NASA Technical Reports Server (NTRS)

Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George N.; Mata, Carlos T.; Mata, Angel. G.; Snyder, Gary P.

2014-01-01

An intrinsic optical-fiber sensor based on Faraday Effect is developed that is highly suitable for measuring lightning current on aircraft, towers and complex structures. Originally developed specifically for aircraft installations, it is light-weight, non-conducting, structure conforming, and is immune to electromagnetic interference, hysteresis and saturation. It can measure total current down to DC. When used on lightning towers, the sensor can help validate other sensors and lightning detection network measurements. Faraday Effect causes light polarization to rotate when the fiber is exposed to a magnetic field in the direction of light propagation. Thus, the magnetic field strength can be determined from the light polarization change. By forming closed fiber loops and applying Ampere's law, measuring the total light rotation yields the total current enclosed. A broadband, dual-detector, reflective polarimetric scheme allows measurement of both DC component and AC waveforms with a 60 dB dynamic range. Two systems were built that are similar in design but with slightly different sensitivities. The 1310nm laser system can measure 300 A - 300 kA, and has a 15m long sensing fiber. It was used in laboratory testing, including measuring current on an aluminum structure simulating an aircraft fuselage or a lightning tower. High current capabilities were demonstrated up to 200 kA at a lightning test facility. The 1550nm laser system can measure 400 A - 400 kA and has a 25m fiber length. Used in field measurements, excellent results were achieved in the summer of 2012 measuring rocket-triggered lightning at the International Center for Lightning Research and Testing (ICLRT), Camp Blanding, Florida. In both systems increased sensitivity can be achieved with multiple fiber loops. The fiber optic sensor provides many unique capabilities not currently possible with traditional sensors. It represents an important new tool for lightning current measurement where low weight, complex shapes, large structure dimension, large current, and low frequency capabilities are important considerations.

Enhancement of pump absorption efficiency by bending and twisting of double clad rare earth doped fibers (Conference Presentation)

NASA Astrophysics Data System (ADS)

Koška, Pavel; Peterka, Pavel; Doya, Valérie; Aubrecht, Jan; Kasik, Ivan; Podrazký, Ondřej

2017-05-01

High-power operation of fiber lasers was enabled by the invention of cladding-pumping in a double-clad fiber structure. Because of existence of so called skew rays in the inner clad of the fiber, pump absorption saturates along the fiber and pumping becomes inefficient. First studies of pump absorption efficiency enhancement were focused on fibers with broken circular symmetry of inner cladding eliminating skew rays [1,2]. Later, techniques of unconventional fiber coiling were proposed [3]. However, theoretical studies were limited to the assumption of a straight fiber. Even recently, the rigorous model accounting for fiber bending and twisting was described [4-6]. It was found that bending of the fiber influences modal spectra of the pump radiation and twisting provides quite efficient mode-scrambling. These effects in a synergic manner significantly enhances pump absorption rate in double clad fibers and improves laser system efficiency. In our contribution we review results of numerical modelling of pump absorption in various types of double-clad fibers, e.g., with cross section shape of hexagon, stadium, and circle; two-fiber bundle (so-called GTWave fiber structure) a panda fibers are also analyzed. We investigate pump field modal spectra evolution in hexagonally shaped fiber in straight, bended, and simultaneously bended and twisted fiber which brings new quality to understanding of the mode-scrambling and pump absorption enhancement. Finally, we evaluate the impact of enhanced pump absorption on signal gain in the fiber. These results can have practical impact in construction of fiber lasers: with pump absorption efficiency optimized by our new model (the other models did not take into account fiber twist), the double-clad fiber of shorter length can be used in the fiber lasers and amplifiers. In such a way the harmful influence of background losses and nonlinear effects can be minimized. [1] Doya, V., Legrand, O., Mortessagne, F., "Optimized absorption in a chaotic double-clad fiber amplifier," Opt. Lett., vol. 26, no. 12, pp. 872-874, (2001). [2] Kouznetsov, D., Moloney, J. V., "Efficiency of pump absorption in double-clad fiber amplifiers. II. Broken circular symmetry," J. Opt. Soc. Am. B, vol. 19, no. 6, pp. 1259-1263, June 2002. [3] Li, Y., Jackson, S. D., Fleming, S., "High absorption and low splice loss properties of hexagonal double-clad fiber," IEEE Photonics Technol. Lett., vol 16, no. 11, pp. 2502-2504, Nov. 2004. [4] Ko\\vska, P. and Peterka, P., "Numerical analysis of pump propagation and absorption in specially tailored double-clad rare-earth doped fiber," Optical and Quantum Electronics, vol. 47, no. 9, pp. 3181-3191 (2015). [5] Ko\\vska, P., Peterka, P., and Doya, V., "Numerical modeling of pump absorption in coiled and twisted double-clad fibers," IEEE J. Sel. Top. Quantum Electron., vol. 22, no. 2 (2016). [6] Ko\\vska, P., Peterka, P., Aubrecht, J., Podrazký, O., Todorov, F., Becker, M., Baravets, Y., Honzátko, P., and Kašík, I., "Enhanced pump absorption efficiency in coiled and twisted double-clad thulium-doped fibers," Opt. Express, vol. 24, no. 1, pp. 102-107 (2016).

In situ thermal conductivity of gas-hydrate-bearing sediments of the Mallik 5L-38 well

NASA Astrophysics Data System (ADS)

Henninges, J.; Huenges, E.; Burkhardt, H.

2005-11-01

Detailed knowledge about thermal properties of rocks containing gas hydrate is required in order to quantify processes involving gas hydrate formation and decomposition in nature. In the framework of the Mallik 2002 program, three wells penetrating a continental gas hydrate occurrence under permafrost were successfully equipped with permanent fiber-optic distributed temperature sensing cables. Temperature data were collected over a 21-month period after completing the wells. Thermal conductivity profiles were calculated from the geothermal data as well as from a petrophysical model derived from the available logging data and application of mixing law models. Results indicate that thermal conductivity variations are mainly lithologically controlled with a minor influence from hydrate saturation. Average thermal conductivity values of the hydrate-bearing sediments range between 2.35 and 2.77 W m-1 K-1. Maximum gas hydrate saturations can reach up to about 90% at an average porosity of 0.3.

Energy and macronutrient intake and dietary pattern among school children in Bahrain: a cross-sectional study

PubMed Central

2011-01-01

Background Obesity is increasing in Bahrain and there is lack of information on the energy and macronutrient intake of children. The objective of this research was to study the energy and macronutrient intake as well as food frequency pattern of Bahraini school children. Methods This is a cross-sectional descriptive study conducted on Bahraini school boys and girls aged 6-18 years from all the 11 populated regions of the country. Data on food intake consisted of a 24-hour dietary recall and was obtained by interviewing a sub-sample of the study population. Information was also obtained through a self-administered questionnaire for the entire sample on the weekly frequency of food items that were grouped into 7 categories based on similarity of nutrient profiles. Dietary analysis was performed using the Nutritionist 5 (First Data Bank Version 1.6 1998). Results While the average energy intake of students was close to the Estimated Average Requirements of the UK Reference standards, protein intake substantially exceeded the Reference Nutrient Intake values as did daily sugar consumption. Dietary fiber fell short of the Dietary Recommended Values (UK) and 36%-50% students exceeded the Energy % limits for total fat, saturated fat and cholesterol. The Polyunsaturated: Saturated fat ratio remained at an unacceptable level of 0.6 for girls and boys. While sweets, snacks and regular soda drinks were popular, milk, fruits and vegetables were not commonly consumed. Conclusions High sugar consumption, low intake of dietary fiber and high energy % of saturated fat and dietary cholesterol by many Bahraini children, is likely to increase their risk of obesity and cardiovascular diseases in later life. Nutrition education programs in schools should emphasize the importance of healthy balanced diets for growth and health maintenance of children as well as dietary prevention of diseases. PMID:21645325

Two-Dimensional CH3NH3PbI3 Perovskite Nanosheets for Ultrafast Pulsed Fiber Lasers.

PubMed

Li, Pengfei; Chen, Yao; Yang, Tieshan; Wang, Ziyu; Lin, Han; Xu, Yanhua; Li, Lei; Mu, Haoran; Shivananju, Bannur Nanjunda; Zhang, Yupeng; Zhang, Qinglin; Pan, Anlian; Li, Shaojuan; Tang, Dingyuan; Jia, Baohua; Zhang, Han; Bao, Qiaoliang

2017-04-12

Even though the nonlinear optical effects of solution processed organic-inorganic perovskite films have been studied, the nonlinear optical properties in two-dimensional (2D) perovskites, especially their applications for ultrafast photonics, are largely unexplored. In comparison to bulk perovskite films, 2D perovskite nanosheets with small thicknesses of a few unit cells are more suitable for investigating the intrinsic nonlinear optical properties because bulk recombination of photocarriers and the nonlinear scattering are relatively small. In this research, we systematically investigated the nonlinear optical properties of 2D perovskite nanosheets derived from a combined solution process and vapor phase conversion method. It was found that 2D perovskite nanosheets have stronger saturable absorption properties with large modulation depth and very low saturation intensity compared with those of bulk perovskite films. Using an all dry transfer method, we constructed a new type of saturable absorber device based on single piece 2D perovskite nanosheet. Stable soliton state mode-locking was achieved, and ultrafast picosecond pulses were generated at 1064 nm. This work is likely to pave the way for ultrafast photonic and optoelectronic applications based on 2D perovskites.

2-μm Cr2+: CdSe passively Q-switched laser

NASA Astrophysics Data System (ADS)

Ji, E. C.; Liu, Q.; Yao, Y.; Lu, S.; Lue, Q. T.

2018-02-01

We demonstrate the bleaching characteristics of Cr2+: CdSe (Cr: CdSe) crystal around 2 μm and prove that Cr: CdSe crystal is an effective saturable absorber to obtain Q-switched pulsed output in Tm3+-doped fiber laser pumped Ho: YAG system. The saturable absorption property of Cr: CdSe is investigated with a pulsed source at 2090 nm. The laserinduced damage threshold of uncoated Cr: CdSe is estimated around 9.92 J/cm2 at 2090 nm with the pulse duration of 30 ns. With the measured bleaching curve, the estimated pulse saturation fluence is around 1.06 J/cm2, and the estimated ground-state absorption cross section is 8.97×10-20 cm2, which is very close to the experimental value. The preliminary laser experiments are all finished with an antireflection coated Cr: CdSe crystal to reduce the insertion loss. The maximum output pulse energy is about 1.8 mJ with repetition frequency of 685 Hz, pulse duration of 15.4 ns, and pulse peak power of 115 kW. The pulsed laser wavelength is measured to be 2090.2 nm.

Adaptation, saturation, and physiological masking in single auditory-nerve fibers.

PubMed

Smith, R L

1979-01-01

Results are reviewed concerning some effects, at a units's characteristic frequency, of a short-term conditioning stimulus on the responses to perstimulatory and poststimulatory test tones. A phenomenological equation is developed from the poststimulatory results and shown to be consistent with the perstimulatory results. According to the results and equation, the response to a test tone equals the unconditioned or unadapted response minus the decrement produced by adaptation to the conditioning tone. Furthermore, the decrement is proportional to the driven response to the conditioning tone and does not depend on sound intensity per se. The equation has a simple interpretation in terms of two processes in cascade--a static saturating nonlinearity followed by additive adaptation. Results are presented to show that this functional model is sufficient to account for the "physiological masking" produced by wide-band backgrounds. According to this interpretation, a sufficiently intense background produces saturation. Consequently, a superimposed test tone cause no change in response. In addition, when the onset of the background precedes the onset of the test tone, the total firing rate is reduced by adaptation. Evidence is reviewed concerning the possible correspondence between the variables in the model and intracellular events in the auditory periphery.

Dynamics and mechanisms of asbestos-fiber aggregate growth in water

NASA Astrophysics Data System (ADS)

Wu, L.; Ortiz, C. P.; Jerolmack, D. J.

2015-12-01

Most colloidal particles including asbestos fibers form aggregates in water, when solution chemistry provides favorable conditions. To date, the growth of colloidal aggregates has been observed in many model systems under optical and scanning electron microscopy; however, all of these studies have used near-spherical particles. The highly elongated nature of asbestos fibers may cause anomalous aggregate growth and morphology, but this has never been examined. Although the exposure pathway of concern for asbestos is through the air, asbestos particles typically reside in soil that is at least partially saturated, and aggregates formed in the aqueous phase may influence the mobility of particles in the environment. Here we study solution-phase aggregation kinetics of asbestos fibers using a liquid-cell by in situ microscopy, over micron to centimeter length scales and from a tenth of a second to hours. We employ an elliptical particle tracking technique to determine particle trajectories and to quantify diffusivity. Experiments reveal that diffusing fibers join by cross linking, but that such linking is sometimes reversible. The resulting aggregates are very sparse and non-compact, with a fractal dimension that is lower than any previously reported value. Their morphology, growth rate and particle size distribution exhibit non-classical behavior that deviates significantly from observations of aggregates composed of near-spherical particles. We also perform experiments using synthetic colloidal particles, and compare these to asbestos in order to separate the controls of particle shape vs. material properties. This direct method for quantitatively observing aggregate growth is a first step toward predicting asbestos fiber aggregate size distributions in the environment. Moreover, many emerging environmental contaminants - such as carbon nanotubes - are elongated colloids, and our work suggests that theories for aggregate growth may need to be modified in order to model these particles.

Isolation of low-molecular-weight proteins from amyloid plaque fibers in Alzheimer's disease.

PubMed

Selkoe, D J; Abraham, C R; Podlisny, M B; Duffy, L K

1986-06-01

During aging of the human brain, and particularly in Alzheimer's disease, progressive neuronal loss is accompanied by the formation of highly stable intra- and extraneuronal protein fibers. Using fluorescence-activated particle sorting, a method has been developed for purifying essentially to homogeneity the extracellular amyloid fibers that form the cores of senile plaques. The purified plaque cores each contain 60-130 pg of protein. Their amino acid composition shows abundant glycine, trace proline, and approximately 50% hydrophobic residues; it resembles that of enriched fractions of the paired helical filaments (PHF) that accumulate intraneuronally in Alzheimer's disease. Senile plaque amyloid fibers share with PHF insolubility in numerous protein denaturants and resistance to proteinases. However, treatment of either fiber preparation with concentrated (88%) formic acid or saturated (6.8 M) guanidine thiocyanate followed by sodium dodecyl sulfate causes disappearance of the fibers and releases proteins migrating at 5-7,000 and 11-15,000 Mr which appear to be dimerically related. Following their separation by size-exclusion HPLC, the proteins solubilized from plaque amyloid and PHF-enriched fractions have highly similar compositions and, on dialysis, readily aggregate into higher Mr polymers. Antibodies raised to the major low-Mr protein selectively label both plaque cores and vascular amyloid deposits in Alzheimer brain but do not stain neurofibrillary tangles, senile plaque neurites, or any other neuronal structure. Thus, extraneuronal amyloid plaque filaments in Alzheimer's disease are composed of hydrophobic low-Mr protein(s) which are also present in vascular amyloid deposits. Current evidence suggests that such protein(s) found in PHF-enriched fractions may derive from copurifying amyloid filaments rather than from PHF.

Proteomic Analysis of Lipid Raft-Like Detergent-Resistant Membranes of Lens Fiber Cells

PubMed Central

Wang, Zhen; Schey, Kevin L.

2015-01-01

Purpose Plasma membranes of lens fiber cells have high levels of long-chain saturated fatty acids, cholesterol, and sphingolipids—key components of lipid rafts. Thus, lipid rafts are expected to constitute a significant portion of fiber cell membranes and play important roles in lens biology. The purpose of this study was to characterize the lens lipid raft proteome. Methods Quantitative proteomics, both label-free and iTRAQ methods, were used to characterize lens fiber cell lipid raft proteins. Detergent-resistant, lipid raft membrane (DRM) fractions were isolated by sucrose gradient centrifugation. To confirm protein localization to lipid rafts, protein sensitivity to cholesterol removal by methyl-β-cyclodextrin was quantified by iTRAQ analysis. Results A total of 506 proteins were identified in raft-like detergent-resistant membranes. Proteins identified support important functions of raft domains in fiber cells, including trafficking, signal transduction, and cytoskeletal organization. In cholesterol-sensitivity studies, 200 proteins were quantified and 71 proteins were strongly affected by cholesterol removal. Lipid raft markers flotillin-1 and flotillin-2 and a significant fraction of AQP0, MP20, and AQP5 were found in the DRM fraction and were highly sensitive to cholesterol removal. Connexins 46 and 50 were more abundant in nonraft fractions, but a small fraction of each was found in the DRM fraction and was strongly affected by cholesterol removal. Quantification of modified AQP0 confirmed that fatty acylation targeted this protein to membrane raft domains. Conclusions These data represent the first comprehensive profile of the lipid raft proteome of lens fiber cells and provide information on membrane protein organization in these cells. PMID:26747763

Encoding of a spectrally-complex communication sound in the bullfrog's auditory nerve.

PubMed

Schwartz, J J; Simmons, A M

1990-02-01

1. A population study of eighth nerve responses in the bullfrog, Rana catesbeiana, was undertaken to analyze how the eighth nerve codes the complex spectral and temporal structure of the species-specific advertisement call over a biologically-realistic range of intensities. Synthetic advertisement calls were generated by Fourier synthesis and presented to individual eighth nerve fibers of anesthetized bullfrogs. Fiber responses were analyzed by calculating rate responses based on post-stimulus-time (PST) histograms and temporal responses based on Fourier transforms of period histograms. 2. At stimulus intensities of 70 and 80 dB SPL, normalized rate responses provide a fairly good representation of the complex spectral structure of the stimulus, particularly in the low- and mid-frequency range. At higher intensities, rate responses saturate, and very little of the spectral structure of the complex stimulus can be seen in the profile of rate responses of the population. 3. Both AP and BP fibers phase-lock strongly to the fundamental (100 Hz) of the complex stimulus. These effects are relatively resistant to changes in stimulus intensity. Only a small number of fibers synchronize to the low-frequency spectral energy in the stimulus. The underlying spectral complexity of the stimulus is not accurately reflected in the timing of fiber firing, presumably because firing is 'captured' by the fundamental frequency. 4. Plots of average localized synchronized rate (ALSR), which combine both spectral and temporal information, show a similar, low-pass shape at all stimulus intensities. ALSR plots do not generally provide an accurate representation of the structure of the advertisement call. 5. The data suggest that anuran peripheral auditory fibers may be particularly sensitive to the amplitude envelope of sounds.

[Potential risk factors for children in the family diet].

PubMed

Pavlović, M; Bijelović, S; Berenji, K; Balać, D

2001-01-01

It has been proven that high-energy diet with predominance of saturated fatty acids, cholesterol, animal proteins and sugar increases disease incidence. The aim of this study was to determine the potential risk factors of family diet of schoolchildren in Subotica. Evaluation of energy and nutrient intake in family diet (n = 357 families with schoolchildren) was examined by a Food Consumption Questionnaire during 7 days in February-March 1998. Data were elaboreted using a software "NUTQ". The potential nutritive risk factors were determined according to Recommended Dietary Allowances (RDA) index of dietary adequacy, as well as Population Nutrition Goals. Mean energy intake was 2197 kcal, where proteins made 14.64%, fats 41.39% and carbohydrates 43.97%. Mean intake of dietary saturated fatty acids (S) was 11.17%, of polyunsaturated fatty acids (P) 14.39%, of monounsaturated fatty acids 15.82%, dietary cholesterol 82.68 g/1000 kcal, dietary fiber 10.67 g daily, while the P/S ratio was 1.28. Analytical questionnaire of schoolchildren family diet shows that daily about 7.5% of children take in more than 30% of fats, 7% of them over 300 mg of dietary cholesterol, 65% of them over 10% of refined sugars, 50% of them over 10% of saturated fatty acids and all of them more than 6 g of NaCl and less than 20 g of dietary fiber a day. According to WHO recommendations, the average daily energy intake values are appropriate for boys, but exceeding for girls aged ten. Domination of meat, meat products, fats, oils, sugars, as well as mean intake of total fats, saturated fatty acids, potassium and sodium, represent potential nutritive risk factors for developing cardiovascular diseases, which are at the first place of morbidity and the second cause of mortality. In regard to our data from 1998, which have shown that among schoolchildren (n = 478) 10.04% boys and 11.47% girls were obese, 8.55% boys and 6.42% girls were overweight, 9.15% had hypercholesterolemia, 14.83% had hypertrigliceridemia and 17.28% had elevated level of LDL-cholesterol, we have to admit that preventive actions regarding healthy nutrition policy is necessary in our society. Nutritional risk factors in diet of average children in Subotica demand prompt preventive actions in order to prevent nutrition disorders.

Simple pre-distortion schemes for improving the power efficiency of SOA-based IR-UWB over fiber systems

NASA Astrophysics Data System (ADS)

Taki, H.; Azou, S.; Hamie, A.; Al Housseini, A.; Alaeddine, A.; Sharaiha, A.

2017-01-01

In this paper, we investigate the usage of SOA for reach extension of an impulse radio over fiber system. Operating in the saturated regime translates into strong nonlinearities and spectral distortions, which drops the power efficiency of the propagated pulses. After studying the SOA response versus operating conditions, we have enhanced the system performance by applying simple analog pre-distortion schemes for various derivatives of the Gaussian pulse and their combination. A novel pulse shape has also been designed by linearly combining three basic Gaussian pulses, offering a very good spectral efficiency (> 55 %) for a high power (0 dBm) at the amplifier input. Furthermore, the potential of our technique has been examined considering a 1.5 Gbps-OOK and 0.75 Gbps-PPM modulation schemes. Pre-distortion proved an advantage for a large extension of optical link (150 km), with an inline amplification via SOA at 40 km.

Health effects of vegan diets.

PubMed

Craig, Winston J

2009-05-01

Recently, vegetarian diets have experienced an increase in popularity. A vegetarian diet is associated with many health benefits because of its higher content of fiber, folic acid, vitamins C and E, potassium, magnesium, and many phytochemicals and a fat content that is more unsaturated. Compared with other vegetarian diets, vegan diets tend to contain less saturated fat and cholesterol and more dietary fiber. Vegans tend to be thinner, have lower serum cholesterol, and lower blood pressure, reducing their risk of heart disease. However, eliminating all animal products from the diet increases the risk of certain nutritional deficiencies. Micronutrients of special concern for the vegan include vitamins B-12 and D, calcium, and long-chain n-3 (omega-3) fatty acids. Unless vegans regularly consume foods that are fortified with these nutrients, appropriate supplements should be consumed. In some cases, iron and zinc status of vegans may also be of concern because of the limited bioavailability of these minerals.

ELASTIN: DIMINISHED REACTIVITY WITH ALDEHYDE REAGENTS IN COPPER DEFICIENCY AND LATHYRISM

PubMed Central

Miller, E. J.; Fullmer, Harold M.

1966-01-01

Elastin fibers in the aortas of control, lathyritic, copper-supplemented, and copper-deficient chicks were examined histochemically and chemically for aldehyde content. Diminished staining for aldehydes was obtained in the fibers from the aortas of lathyritic and copper-deficient chicks. Chemical studies of elastin isolated from the aortas of control and lathyritic chicks showed an apparent loss of lysine residues in control elastin to be associated with an increase in aldehyde content providing evidence that lysine is converted to an aldehyde-containing intermediate during biosynthesis of desmosine and isodesmosine. Approximately 6 aldehyde groups were present for every 1000 amino acids in elastin isolated from the aortas of control animals, while the corresponding number in lathyritic elastin was 4. At least two types of aldehydes, saturated and α,β-unsaturated, appear to be associated with elastin, suggesting the presence of more than one intermediate between lysine and the desmosines. PMID:5941783

Method and technique for installing light-weight, fragile, high-temperature fiber insulation

NASA Technical Reports Server (NTRS)

Patel, B. C. (Inventor)

1983-01-01

A method of installing fragile, light weight, high temperature fiber insulation, particularly where the insulation is to be used as a seal strip providing a high order of thermal barrier insulation is discussed. The process is based on provision of a strip of the mineral batting cut oversize by a predetermined amount, saturated in a fugitive polymer solution, compressed in a mold, dried and cured to form a rigidized batting material which is machined to required shape. The machine dimensions would normally be at least nominally less than the dimensions of the cavity to be sealed. After insertion in the cavity, which may be a wire-mesh seal enclosure, the apparatus is subjected to baking at a temperature sufficiently high to cause the resin to burn off cleanly, leaving the batting substantially in its original condition and expanded into the cavity or seal enclosure.

A method and technique for installing light-weight fragile, high-temperature fiber insulation

NASA Technical Reports Server (NTRS)

Ballantine, T. J. (Inventor)

1982-01-01

A method of installing fragile, light-weight, high-temperature fiber insulation, particularly where the insulation is to be used as a seal strip providing a high order of thermal barrier insulation is described. The process is based on provision of a strip of the mineral batting cut oversize by a predetermined amount, saturated in a fugitive polymer solution, compressed in a mold, dried and cured to form a rigidized batting material which may be machined to required shape. The machined dimensions would normally be at least nominally less than the dimensions of the cavity to be sealed. After insertion in the cavity, which may be a wire-mesh seal enclosure, the apparatus is subjected to baking at a temperature sufficiently high to cause the resin to burn off cleanly, leaving the batting substantially in its original condition and expanded into the cavity or seal enclosure.

Widely tunable eye-safe laser by a passively Q-switched photonic crystal fiber laser and an external-cavity optical parametric oscillator

NASA Astrophysics Data System (ADS)

Chang, H. L.; Zhuang, W. Z.; Huang, W. C.; Huang, J. Y.; Huang, K. F.; Chen, Y. F.

2011-09-01

We report on a widely tunable passively Q-switched photonic crystal fiber (PCF) laser with wavelength tuning range up to 80 nm. The PCF laser utilizes an AlGaInAs quantum well/barrier structure as a saturable absorber and incorporates an external-cavity optical parametric oscillator (OPO) to achieve wavelength conversion. Under a pump power of 13.1 W at 976 nm, the PCF laser generated 1029-nm radiation with maximum output energy of 750 μJ and was incident into an external-cavity OPO. The output energy and peak power of signal wave was found to be 138 μJ and 19 kW, respectively. By tuning the temperature of nonlinear crystal, periodically poled lithium niobate (PPLN), in the OPO, the signal wavelength in eye-safe regime from 1513 to 1593 nm was obtained.

Differences in food intake and disparity in obesity rates between adult Jews and Bedouins in southern Israel.

PubMed

Fraser, Drora; Bilenko, Natalya; Vardy, Hillel; Abu-Saad, Kathleene; Shai, Iris; Abu-Shareb, Heijar; Shahar, Danit R

2008-01-01

The goal of this study was to compare eating patterns of Jews and Muslim Bedouins and investigate possible dietary causes for discrepancy in obesity rates. We pooled two surveys that included data from 793 Jews and 169 Bedouins aged 35-64years recruited from 1998 through 2003 in southern Israel. For the Jewish sample, we used a proportional geographic cluster random sample of persons aged > or = 35 years. For the Bedouins, a convenience sample of 519 participants was used. Participants were interviewed at home, using modified 24-hour food questionnaires with additional questions regarding health and eating habits. The Jewish group was older and better educated than were the Bedouins. The Bedouins had a higher age-adjusted body mass index than did the Jews (P = .03), and the rate of obesity was higher among Bedouins than Jews (27.9% vs 20.0%, respectively). Compared to Jewish men, Bedouin men reported lower intake of fat, cholesterol, total saturated fat, and protein and fat as a percentage of total energy, but they reported higher intake of carbohydrates, fiber, and carbohydrates as a percentage of total energy. Bedouin women reported lower intake of total saturated fat, percentage of protein and fat, and higher intake of carbohydrates and fiber than did Jewish women. The Bedouin population is adapting Western eating patterns that appear to be associated with increased obesity. To address this problem, culturally sensitive intervention programs will have to be developed.

The Cardiovascular Health of Urban African-Americans: Dietary Results from the Genes, Nutrition, Exercise, Wellness and Spiritual Growth (GoodNEWS) Trial

PubMed Central

Carson, Jo Ann S.; Michalsky, Linda; Latson, Bernadette; Banks, Kamakki; Tong, Liyue; Gimpel, Nora; Lee, Jenny J.; DeHaven, Mark J.

2012-01-01

African-Americans have a higher incidence of cardiovascular disease (CVD) than Americans in general and are thus prime targets for efforts to reduce CVD risk. Dietary intake data were obtained from African-Americans participating in the GoodNEWS trial. The 286 females and 71 males had a mean age of 49 years; 53% had hypertension, 65% had dyslipidemia and 51% met criteria for metabolic syndrome. Their dietary intakes were compared to American Heart Association and National Heart Lung and Blood Institute nutritional parameters to identify areas for improvement to reduce CVD risk in this group of urban church members in Dallas, Texas. Results from administration of the Dietary History Questionnaire (DHQ) indicated median daily intakes of 33.6 % of energy from total fat, 10.3% of energy from saturated fat, 171 mg cholesterol, 16.3 g dietary fiber, and 2453 mg sodium. A beneficial median intake of 2.9 cups of fruits and vegetable/day was coupled with only 2.7 oz fish/week and an excessive intake of 13 tsp added sugar/day. These data indicate several changes needed to bring the diets of these individuals, and likely many other urban African-Americans, in line with national recommendations: reduction of saturated fat, sodium and sugar intake, while increasing intake of fatty fish and whole grains. The frequent inclusion of vegetables should be encouraged in ways that promote achievement of recommended intakes of energy, fat, fiber and sodium. PMID:22995059

Dietary Fat, Fiber, and Carbohydrate Intake and Endogenous Hormone Levels in Premenopausal Women

PubMed Central

Cui, Xiaohui; Rosner, Bernard; Willett, Walter C; Hankinson, Susan E

2011-01-01

The authors conducted a cross-sectional study to investigate the associations of fat, fiber and carbohydrate intake with endogenous estrogen, androgen, and insulin-like growth factor (IGF) levels among 595 premenopausal women. Overall, no significant associations were found between dietary intake of these macronutrients and plasma sex steroid hormone levels. Dietary fat intake was inversely associated with IGF-I and IGF-binding protein 3 (IGFBP-3) levels. When substituting 5% of energy from total fat for the equivalent amount of energy from carbohydrate or protein intake, the plasma levels of IGF-I and IGFBP-3 were 2.8% (95% confidence interval [CI] 0.3, 5.3) and 1.6% (95% CI 0.4, 2.8) lower, respectively. Animal fat, saturated fat and monounsaturated fat intakes also were inversely associated with IGFBP-3 levels (P < 0.05). Carbohydrates were positively associated with plasma IGF-I level. When substituting 5% of energy from carbohydrates for the equivalent amount of energy from fat or protein intake, the plasma IGF-I level was 2.0% (95% CI 0.1, 3.9%) higher. No independent associations between fiber intake and hormone levels were observed. The results suggest that a low-fat/high-fiber or carbohydrate diet is not associated with endogenous levels of sex steroid hormones, but it may modestly increase IGF-I and IGFBP-3 levels among premenopausal women. PMID:21761370

Toward optical guidance during endoscopic ultrasound-guided fine needle aspirations of pancreatic masses using single fiber reflectance spectroscopy: a feasibility study

NASA Astrophysics Data System (ADS)

Stegehuis, Paulien L.; Boogerd, Leonora S. F.; Inderson, Akin; Veenendaal, Roeland A.; van Gerven, P.; Bonsing, Bert A.; Sven Mieog, J.; Amelink, Arjen; Veselic, Maud; Morreau, Hans; van de Velde, Cornelis J. H.; Lelieveldt, Boudewijn P. F.; Dijkstra, Jouke; Robinson, Dominic J.; Vahrmeijer, Alexander L.

2017-02-01

Endoscopic ultrasound-guided fine needle aspirations (EUS-FNA) of pancreatic masses suffer from sample errors and low-negative predictive values. Fiber-optic spectroscopy in the visible to near-infrared wavelength spectrum can noninvasively extract physiological parameters from tissue and has the potential to guide the sampling process and reduce sample errors. We assessed the feasibility of single fiber (SF) reflectance spectroscopy measurements during EUS-FNA of pancreatic masses and its ability to distinguish benign from malignant pancreatic tissue. A single optical fiber was placed inside a 19-gauge biopsy needle during EUS-FNA and at least three reflectance measurements were taken prior to FNA. Spectroscopy measurements did not cause any related adverse events and prolonged procedure time with ˜5 min. An accurate correlation between spectroscopy measurements and cytology could be made in nine patients (three benign and six malignant). The oxygen saturation and bilirubin concentration were significantly higher in benign tissue compared with malignant tissue (55% versus 21%, p=0.038; 166 μmol/L versus 17 μmol/L, p=0.039, respectively). To conclude, incorporation of SF spectroscopy during EUS-FNA was feasible, safe, and relatively quick to perform. The optical properties of benign and malignant pancreatic tissue are different, implying that SF spectroscopy can potentially guide the FNA sampling.

A Fiber-Optic Aircraft Lightning Current Measurement Sensor

NASA Technical Reports Server (NTRS)

Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George N.

2013-01-01

A fiber-optic current sensor based on the Faraday Effect is developed for aircraft installations. It can measure total lightning current amplitudes and waveforms, including continuing current. Additional benefits include being small, lightweight, non-conducting, safe from electromagnetic interference, and free of hysteresis and saturation. The Faraday Effect causes light polarization to rotate in presence of magnetic field in the direction of light propagation. Measuring the total induced light polarization change yields the total current enclosed. The system operates at 1310nm laser wavelength and can measure approximately 300 A - 300 kA, a 60 dB range. A reflective polarimetric scheme is used, where the light polarization change is measured after a round-trip propagation through the fiber. A two-detector setup measures the two orthogonal polarizations for noise subtraction and improved dynamic range. The current response curve is non-linear and requires a simple spline-fit correction. Effects of high current were achieved in laboratory using combinations of multiple fiber and wire loops. Good result comparisons against reference sensors were achieved up to 300 kA. Accurate measurements on a simulated aircraft fuselage and an internal structure illustrate capabilities that maybe difficult with traditional sensors. Also tested at a commercial lightning test facility from 20 kA to 200 kA, accuracy within 3-10% was achieved even with non-optimum setups.

Multichannel fiber-based diffuse reflectance spectroscopy for the rat brain exposed to a laser-induced shock wave: comparison between ipsi- and contralateral hemispheres

NASA Astrophysics Data System (ADS)

Miyaki, Mai; Kawauchi, Satoko; Okuda, Wataru; Nawashiro, Hiroshi; Takemura, Toshiya; Sato, Shunichi; Nishidate, Izumi

2015-03-01

Due to considerable increase in the terrorism using explosive devices, blast-induced traumatic brain injury (bTBI) receives much attention worldwide. However, little is known about the pathology and mechanism of bTBI. In our previous study, we found that cortical spreading depolarization (CSD) occurred in the hemisphere exposed to a laser- induced shock wave (LISW), which was followed by long-lasting hypoxemia-oligemia. However, there is no information on the events occurred in the contralateral hemisphere. In this study, we performed multichannel fiber-based diffuse reflectance spectroscopy for the rat brain exposed to an LISW and compared the results for the ipsilateral and contralateral hemispheres. A pair of optical fibers was put on the both exposed right and left parietal bone; white light was delivered to the brain through source fibers and diffuse reflectance signals were collected with detection fibers for both hemispheres. An LISW was applied to the left (ipsilateral) hemisphere. By analyzing reflectance signals, we evaluated occurrence of CSD, blood volume and oxygen saturation for both hemispheres. In the ipsilateral hemispheres, we observed the occurrence of CSD and long-lasting hypoxemia-oligemia in all rats examined (n=8), as observed in our previous study. In the contralateral hemisphere, on the other hand, no occurrence of CSD was observed, but we observed oligemia in 7 of 8 rats and hypoxemia in 1 of 8 rats, suggesting a mechanism to cause hypoxemia or oligemia or both that is (are) not directly associated with CSD in the contralateral hemisphere.

A simple way to an ultra-robust superhydrophobic fabric with mechanical stability, UV durability, and UV shielding property.

PubMed

Ren, Guina; Song, Yuanming; Li, Xiangming; Wang, Bo; Zhou, Yanli; Wang, Yuyan; Ge, Bo; Zhu, Xiaotao

2018-07-15

Development of an ultra-robust superhydrophobic fabric with mechanical stability, UV durability, and UV shielding by a simple method is highly desirable, yet it remains a challenge that current technologies have been unable to fully address. Herein, the original fabric is immersed into the solution containing ZnO nanoparticle and PDMS (polydimethylsiloxane), and the fiber surfaces are uniformly covered by a ZnO-PDMS layer after thermal treatment at 110 °C for 30 min. Droplets of water and corrosive liquids including strong acid, strong alkali, and saturated salt solution display sphere shape on the ZnO-PDMS coated fabric surface. The stable binding of ZnO-PDMS layer onto the fibers allows for the fabric coating with robust superhydrophobicity, and the coated fabric still displays superhydrophobicity after hand twisting, knife scratching, finger touching, and even cycles of sandpaper abrasion. The ZnO-PDMS coated fabric can also keep its superhydrophobic property when exposed to long term UV illumination, demonstrating its UV resistance. Moreover, the uniformly distribution of ZnO nanoparticles on fibers allows the ZnO-PDMS coated fabric to display UV shielding property. Copyright © 2018 Elsevier Inc. All rights reserved.

Experimental and numerical study of high order Stokes lines in Brillouin-erbium fiber laser

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

Yuan, Yijun; College of Physics Science and Engineering Technology, Yichun University, Yichun, Jiangxi Province 336000; Yao, Yong, E-mail: yaoyong@hit.edu.cn

2014-01-28

We experimentally study the dependences of high-order Stokes lines on the erbium-doped fiber (EDF) pump power P{sub EDF}, the Brillouin pump (BP) power P{sub BP}, and its working wavelength in a multiwavelength Brillouin erbium-doped fiber laser (MBEFL). By using the rate and propagation equations, and the coupled wave equations of stimulated Brillouin scattering, we establish a lumped model to describe the MBEFL. Numerical simulations show that the number of Stokes lines can be increased by decreasing the spacing between the BP wavelength and the EDF peak gain or P{sub BP} as long as it is larger than a critical valuemore » P{sub BP}{sup (cr)}=1.7 mW, or by increasing P{sub EDF} without reaching a saturation value P{sub EDF}{sup (cr)}=250 mW. However, when P{sub BP} and P{sub EDF} are varied beyond P{sub BP}{sup (cr)} and P{sub EDF}{sup (cr)}, respectively, the number of Stokes lines is reduced, accompanied by some self-lasing cavity modes. These results by numerical simulation are consistent with experimental observations from the MBEFL.« less

Rapid Determination of Clenbuterol in Pork by Direct Immersion Solid-Phase Microextraction Coupled with Gas Chromatography-Mass Spectrometry.

PubMed

Ye, Diru; Wu, Susu; Xu, Jianqiao; Jiang, Ruifen; Zhu, Fang; Ouyang, Gangfeng

2016-02-01

Direct immersion solid-phase microextraction (DI-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was developed for rapid analysis of clenbuterol in pork for the first time. In this work, a low-cost homemade 44 µm polydimethylsiloxane (PDMS) SPME fiber was employed to extract clenbuterol in pork. After extraction, derivatization was performed by suspending the fiber in the headspace of the 2 mL sample vial saturated with a vapor of 100 µL hexamethyldisilazane. Lastly, the fiber was directly introduced to GC-MS for analysis. All parameters that influenced absorption (extraction time), derivatization (derivatization reagent, time and temperature) and desorption (desorption time) were optimized. Under optimized conditions, the method offered a wide linear range (10-1000 ng g(-1)) and a low detection limit (3.6 ng g(-1)). Finally, the method was successfully applied in the analysis of pork from the market, and recoveries of the method for spiked pork were 97.4-105.7%. Compared with the traditional solvent extraction method, the proposed method was much cheaper and fast. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Laser Surface Preparation of Epoxy Composites for Secondary Bonding: Optimization of Ablation Depth

NASA Technical Reports Server (NTRS)

Palmieri, Frank L.; Hopkins, John; Wohl, Christopher J.; Lin, Yi; Connell, John W.; Belcher, Marcus A.; Blohowiak, Kay Y.

2015-01-01

Surface preparation has been identified as one of the most critical aspects of attaining predictable and reliable adhesive bonds. Energetic processes such as laser ablation or plasma treatment are amenable to automation and are easily monitored and adjusted for controlled surface preparation. A laser ablation process was developed to accurately remove a targeted depth of resin, approximately 0.1 to 20 micrometers, from a carbon fiber reinforced epoxy composite surface while simultaneously changing surface chemistry and creating micro-roughness. This work demonstrates the application of this process to prepare composite surfaces for bonding without exposing or damaging fibers on the surface. Composite panels were prepared in an autoclave and had a resin layer approximately 10 micrometers thick above the fiber reinforcement. These composite panels were laser surface treated using several conditions, fabricated into bonded panels and hygrothermally aged. Bond performance of aged, experimental specimens was compared with grit blast surface treated specimens using a modified double cantilever beam test that enabled accelerated saturation of the specimen with water. Comparison of bonded specimens will be used to determine how ablation depth may affect average fracture energies and failure modes.

On phaser-based processing of impulse radio UWB over fiber systems employing SOA

NASA Astrophysics Data System (ADS)

Taki, H.; Azou, S.; Hamie, A.; Al Housseini, A.; Alaeddine, A.; Sharaiha, A.

2017-07-01

In this study, we adopt a phaser-based processing to enhance the performance of impulse radio over fiber system utilizing SOA. The amplifier has been placed at a distance in the optical link, so as to extend the coverage area of proposed transceiver. Operating in the linear or saturation region for SOA, adds ASE noise or strong nonlinearities acting on the propagated pulses, respectively. Both lead to a degradation in the power efficiency and bit error rate performance. By applying up and down analog chirping technique, we have reduced the ASE power and nonlinearity simultaneously. Based on the 5th Gaussian pulse and Abraha's combination of doublets, a significant improvement has been achieved at extremely low and high input powers entering the amplifier (<-15 dBm and 0 dBm), recording a very good bit error rate performance and power efficiency. Better signal quality was observed after photo-detector, due to the fact that waveforms with lower frequency components are less affected by SOA nonlinearity. Our scheme has proved to be effective for 1 Gbps OOK and 0.5 Gbps PPM transmissions, while reaching a distance of 160 km in the optical fiber.

Major food sources of calories, added sugars, and saturated fat and their contribution to essential nutrient intakes in the U.S. diet: data from the national health and nutrition examination survey (2003–2006)

PubMed Central

2013-01-01

Background The risk of chronic disease cannot be predicted simply by the content of a single nutrient in a food or food group in the diet. The contribution of food sources of calories, added sugars and saturated fat (SFA) to intakes of dietary fiber and micronutrients of public health importance is also relevant to understanding the overall dietary impact of these foods. Objective Identify the top food sources of calories, added sugars and SFA in the U.S. diet and quantify their contribution to fiber and micronutrient intakes. Methods Single 24-hour dietary recalls (Day 1) collected from participants ≥2 years (n = 16,822) of the What We Eat in America, National Health and Nutrition Examination Survey (WWEIA/NHANES 2003–2006) were analyzed. All analyses included sample weights to account for the survey design. Calorie and nutrient intakes from foods included contributions from disaggregated food mixtures and tabulated by rank order. Results No one food category contributes more than 7.2% of calories to the overall U.S. diet, but half of the top 10 contribute 10% or more of total dietary fiber and micronutrients. Three of the top 10 sources of calories and SFA (beef, milk and cheese) contribute 46.3% of the calcium, 49.5% of the vitamin D, 42.3% of the vitamin B12 as well as other essential nutrients to the American diet. On the other hand, foods categorized as desserts, snacks, or beverages, contribute 13.6% of total calories, 83% of added sugar intake, and provide little or no nutritional value. Including food components of disaggregated recipes more accurately estimated the contribution of foods like beef, milk or cheese to overall nutrient intake compared to “as consumed” food categorizations. Conclusions Some food sources of calories, added sugars and SFA make major contributions to American dietary fiber and micronutrient intakes. Dietary modifications targeting reductions in calories, added sugar, or SFA need to take these key micronutrient sources into account so as not to have the unintended consequence of lowering overall dietary quality. PMID:23927718

Morphological Constraints on Cerebellar Granule Cell Combinatorial Diversity.

PubMed

Gilmer, Jesse I; Person, Abigail L

2017-12-13

Combinatorial expansion by the cerebellar granule cell layer (GCL) is fundamental to theories of cerebellar contributions to motor control and learning. Granule cells (GrCs) sample approximately four mossy fiber inputs and are thought to form a combinatorial code useful for pattern separation and learning. We constructed a spatially realistic model of the cerebellar GCL and examined how GCL architecture contributes to GrC combinatorial diversity. We found that GrC combinatorial diversity saturates quickly as mossy fiber input diversity increases, and that this saturation is in part a consequence of short dendrites, which limit access to diverse inputs and favor dense sampling of local inputs. This local sampling also produced GrCs that were combinatorially redundant, even when input diversity was extremely high. In addition, we found that mossy fiber clustering, which is a common anatomical pattern, also led to increased redundancy of GrC input combinations. We related this redundancy to hypothesized roles of temporal expansion of GrC information encoding in service of learned timing, and we show that GCL architecture produces GrC populations that support both temporal and combinatorial expansion. Finally, we used novel anatomical measurements from mice of either sex to inform modeling of sparse and filopodia-bearing mossy fibers, finding that these circuit features uniquely contribute to enhancing GrC diversification and redundancy. Our results complement information theoretic studies of granule layer structure and provide insight into the contributions of granule layer anatomical features to afferent mixing. SIGNIFICANCE STATEMENT Cerebellar granule cells are among the simplest neurons, with tiny somata and, on average, just four dendrites. These characteristics, along with their dense organization, inspired influential theoretical work on the granule cell layer as a combinatorial expander, where each granule cell represents a unique combination of inputs. Despite the centrality of these theories to cerebellar physiology, the degree of expansion supported by anatomically realistic patterns of inputs is unknown. Using modeling and anatomy, we show that realistic input patterns constrain combinatorial diversity by producing redundant combinations, which nevertheless could support temporal diversification of like combinations, suitable for learned timing. Our study suggests a neural substrate for producing high levels of both combinatorial and temporal diversity in the granule cell layer. Copyright © 2017 the authors 0270-6474/17/3712153-14$15.00/0.

Generation of High-Frequency P and S Wave Radiation from Underground Explosions

DTIC Science & Technology

2011-12-30

3.0 3.5 4.0 2024-T3, 1.63<tɚ.54 mm Homalite-100 Ti - 6Al - 4V , t=1.2 mm Epoxy/Graphite Fiber Composite (a) (b) Figure 3: Normalized Dynamic Stress... porosity . The gas porosity also gives some information about effects associated with the water table since water saturated rock has zero gas porosity ...medium than to the depth. Since velocity and density are strongly correlated with the gas porosity , it was not possible to determine which had the

Proceedings of the ADPA/AIAA/ASME/SPIE Conference on Active and Adaptive Structures Held in Alexandria, Virginia on November 4 - 8, 1991

DTIC Science & Technology

1991-11-08

saturation limit. The control action is sent via a digital-to-analog converter to a power amplifier to activate the NITINOL fibers embedded inside the...feedback approaches in the design of a modal- eiipl.’ i,, n e .ti )tal filters with feedfor.ard and feedback based active control system. There are...photocells; and a series of narrow bandpass filters with silicon photodetectors. The sensor outputs are fed through an anolog to digital converter into the

Improved Performance of an Optically Pumped Mid-Infrared Acetylene-Filled Hollow-Core Fiber Laser

NASA Astrophysics Data System (ADS)

Dadashzadeh, Neda

The focus of this research is improving the pulse output energy of a mid-IR pulsed acetylene-filled Hollow-core Optical Fiber Gas LASer (HOFGLAS) system. Pump pulses and acetylene molecules interact with each other inside hollow-core photonic crystal fiber that effectively confines light and allows for strong gain. This results in lasing at 3.11 mum and 3.17 mum lines based on population inversion of acetylene molecules, which are optically pumped at rotational-vibrational overtones near 1.5 mum using 1 ns pulse duration from an optical parametric amplifier (OPA). This acetylene laser operates with no cavity mirrors because of a high gain in a single pass configuration. There are few laser sources in the mid-IR region while there are many applications for having a laser source in this range such as remote sensing, hazardous chemical detection, and breath analysis. This adds to the importance of the acetylene-filled HOFGLAS system. Some of the applications like remote sensing require high power. So, we moved toward power scaling this laser system by optimizing the laser operation through maximizing the OPA alignment to improve its modal content using longer length of fiber to increase the interaction length and improving the beam quality of the mid-IR emissions. The highest pulse energy ever obtained in the 3 microm mid-IR region from the acetylene-filled HOFGLAS after applying the improvements is reported here (1.4 muJ). Higher mid-IR pulse energies can be achieved by improving the pulse energy achievable from the OPA pump source and working with longer pulse duration to decrease the bandwidth of the OPA. This operation demonstrates many novel properties of acetylene-filled pulsed mid-IR hollow-core fiber lasers. The excellent spatial beam quality at highest power and phenomenological scaling of saturation power and efficiency with pressure that we observe point to the promise of power scaling and motivate further development of numerical models of the laser for deeper insight into these effects. M2 measurement method was used to examine spatial beam quality and it was found to be fiber-dependent. For the improved setup, M2 was investigated at several input pump powers in addition to the reproducibility checks. M 2 of 1.14 at the maximum output power motivates for beam combining to scale to higher power. The independence of efficiency on pressure is an evidence for reaching higher mid-IR power at a pressure where saturation behavior does not exist. achieving the highest mid-IR power to date, 1.4 muJ, encourages for building higher power OPA to produce high power mid-IR emissions. Taken as a whole, this laser exhibits novel behavior that motivates both numerical/theoretical investigation and further efforts to scale to higher powers.

Passivation of black phosphorus saturable absorbers for reliable pulse formation of fiber lasers

NASA Astrophysics Data System (ADS)

Na, Dongsoo; Park, Kichul; Park, Ki-Hwan; Song, Yong-Won

2017-11-01

Black phosphorus (BP) has attracted increasing attention due to its unique electrical properties. In addition, the outstanding optical nonlinearity of BP has been demonstrated in various ways. Its functionality as a saturable absorber, in particular, has been validated in demonstrations of passive mode-locked lasers. However, normally, the performance of BP is degraded eventually by both thermal and chemical damage in ambient conditions. The passivation of BP is the critical issue to guarantee a stable performance of the optical devices. We quantitatively characterized the mode-locked lasers operated by BP saturable absorbers with diversified passivation materials such as polydimethylsiloxane (PDMS) or Al2O3, considering the atomic structure of the materials, and therefore the hydro-permeability of the passivation layers. Unlike the BP layers without passivation, we demonstrated that the Al2O3-passivated BP layer was protected from the surface oxidation reaction in the long-term, and the PDMS-passivated one had a short-term blocking effect. The quantitative analysis showed that the time-dependent characteristics of the pulsed laser without passivation were changed with respect to the pulse duration, spectral width, and time-bandwidth product displaying 550 fs, 2.8 nm, and 0.406, respectively. With passivation, the changes were limited to <43 fs, <0.3 nm, and <0.012, respectively.

Macro Fiber Piezocomposite Actuator Poling Study

NASA Technical Reports Server (NTRS)

Werlink, Rudy J.; Bryant, Robert G.; Manos, Dennis

2002-01-01

The performance and advantages of Piezocomposite Actuators are to provide a low cost, in-situ actuator/sensor that is flexible, low profile and high strain per volt performance in the same plane of poled voltage. This paper extends reported data for the performance of these Macrofiber Composite (MFC) Actuators to include 4 progressively narrower Intedigitized electrode configurations with several line widths and spacing ratios. Data is reported for max free strain, average strain per applied volt, poling (alignment of the electric dipoles of the PZT ceramic) voltage vs. strain and capacitance, time to poling voltage 95% saturation. The output strain per volt progressively increases as electrode spacing decreases, with saturation occurring at lower poling voltages. The narrowest spacing ratio becomes prone to voltage breakdown or short circuits limiting the spacing width with current fabrication methods. The capacitance generally increases with increasing poling voltage level but has high sensitivity to factors such as temperature, moisture and time from poling which limit its usefulness as a simple indicator. The total time of applied poling voltage to saturate or fully line up the dipoles in the piezoceramic was generally on the order of 5-20 seconds. Less sensitivity to poling due to the applied rate of voltage increase over a 25 to 500 volt/second rate range was observed.

Nanoscale Platelet Formation by Monounsaturated and Saturated Sophorolipids under Basic pH Conditions.

PubMed

Cuvier, Anne-Sophie; Babonneau, Florence; Berton, Jan; Stevens, Christian V; Fadda, Giulia C; Péhau-Arnaudet, Gérard; Le Griel, Patrick; Prévost, Sylvain; Perez, Javier; Baccile, Niki

2015-12-21

The self-assembly behavior of the yeast-derived bolaamphiphile sophorolipid (SL) is generally studied under acidic/neutral pH conditions, at which micellar and fibrillar aggregates are commonly found, according to the (un)saturation of the aliphatic chain: the cis form, which corresponds to the oleic acid form of SL, spontaneously forms micelles, whereas the saturated form, which corresponds to the stearic acid form of SL, preferentially forms chiral fibers. By using small-angle light and X-ray scattering (SLS, SAXS) combined with high-sensitivity transmission electron microscopy imaging under cryogenic conditions (cryo-TEM), the nature of the self-assembled structures formed by these two compounds above pH 10, which is the pH at which they are negatively charged due to the presence of a carboxylate group, has been explored. Under these conditions, these compounds self-assemble into nanoscale platelets, despite the different molecular structures. This work shows that the electrostatic repulsion forces generated by COO(-) mainly drive the self-assembly process at basic pH, in contrast with that found at pH below neutrality, at which self-assembly is driven by van der Waals forces and hydrogen bonding, and thus, is in agreement with previous findings on carbohydrate-based gemini surfactants. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Passivation of black phosphorus saturable absorbers for reliable pulse formation of fiber lasers.

PubMed

Na, Dongsoo; Park, Kichul; Park, Ki-Hwan; Song, Yong-Won

2017-11-24

Black phosphorus (BP) has attracted increasing attention due to its unique electrical properties. In addition, the outstanding optical nonlinearity of BP has been demonstrated in various ways. Its functionality as a saturable absorber, in particular, has been validated in demonstrations of passive mode-locked lasers. However, normally, the performance of BP is degraded eventually by both thermal and chemical damage in ambient conditions. The passivation of BP is the critical issue to guarantee a stable performance of the optical devices. We quantitatively characterized the mode-locked lasers operated by BP saturable absorbers with diversified passivation materials such as polydimethylsiloxane (PDMS) or Al 2 O 3 , considering the atomic structure of the materials, and therefore the hydro-permeability of the passivation layers. Unlike the BP layers without passivation, we demonstrated that the Al 2 O 3 -passivated BP layer was protected from the surface oxidation reaction in the long-term, and the PDMS-passivated one had a short-term blocking effect. The quantitative analysis showed that the time-dependent characteristics of the pulsed laser without passivation were changed with respect to the pulse duration, spectral width, and time-bandwidth product displaying 550 fs, 2.8 nm, and 0.406, respectively. With passivation, the changes were limited to <43 fs, <0.3 nm, and <0.012, respectively.

Remote Environmental Monitoring and Diagnostics in the Perishables Supply Chain - Phase 2

DTIC Science & Technology

2014-03-20

0 g total  fat  (0 g from  saturated  fat , 0 mg cholesterol), 0 mg sodium, 33 g total carbohydrates (2 g dietary fiber, 19 g  sugars) and 0 g  protein ...has a high source of  protein   made up of about 21% meat.    Nutrition Facts: serving 1 sandwich (100 g), 340 calories (130 calories from  fat ), 14 g...from saturated  fat , 1 g trans‐ fat , 0 mg cholesterol), 320 mg sodium, 34 g total carbohydrates  and 4 g  protein .    Honey BBQ Beef Sandwich, which is

[Hungarian Diet and Nutritional Status Survey - OTÁP2014. II. Energy and macronutrient intake of the Hungarian population].

PubMed

Sarkadi Nagy, Eszter; Bakacs, Márta; Illés, Éva; Nagy, Barbara; Varga, Anita; Kis, Orsolya; Schreiberné Molnár, Erzsébet; Martos, Éva

2017-04-01

The aim of the study was to assess and monitor the dietary habits and nutrient intake of Hungarian adults. Three-day dietary records were used for dietary assessment, the sample was representative for the Hungarian population aged ≥18ys by gender and age. The mean proportion of energy from fat was higher (men: 38 energy%, women: 37 energy%), that from carbohydrates was lower (men: 45 energy%, women: 47 energy%) than recommended, the protein intake is adequate. Unfavorable change compared to the previous survey in 2009 was the increase of fat and saturated fatty acid energy percent in women, the decrease in fruit and vegetable consumption, which explains the decreased fiber intake. An increasing trend in added sugar energy percent in each age groups of both genders was observed compared to 2009. Interventions focusing on the promotion of fruit and vegetable consumption and decreasing of saturated fat and added sugar intake are needed. Orv. Hetil., 2017, 158(15), 587-597.

Comparison of childhood cancer survivors' nutritional intake with US dietary guidelines.

PubMed

Zhang, Fang Fang; Saltzman, Edward; Kelly, Michael J; Liu, Shanshan; Must, Aviva; Parsons, Susan K; Roberts, Susan B

2015-08-01

Despite improved survival, childhood cancer survivors experience significantly elevated risk of premature mortality and serious morbidity due to chronic health conditions. Poor diet quality can exacerbate chronic health conditions in the survivors but their nutritional intake has not been adequately studied. We assessed the Healthy Eating Index 2010 (HEI-2010) in 22 survivors of pediatric acute lymphoblastic leukemia and lymphoma (median age = 11.7 years) and compared survivors' dietary intake to the 2010 Dietary Guidelines for Americans. Dietary data were collected using repeated 24 hr dietary recalls over a 1-year period, which were averaged to estimate habitual intake. The mean HEI-2010 in childhood cancer survivors was 52.7, about 50 percent of the maximum score. Long-term survivors (time from diagnosis ≥10 years) had a significantly lower HEI-2010 than recent survivors (time from diagnosis <5 years) (β = -11.5, 95% CI: -22.1, -0.9, P = 0.047). For individual food groups and nutrients, survivors had a particularly poor adherence to green vegetables and beans, total vegetables, and whole fruits. None of the survivors met the guidelines for dietary fiber and potassium intake. Only 4%, 19%, 24%, and 29% met the guidelines for vitamin D, sodium, calcium, and saturated fat intake. The average intake in relative to the recommended intake was 32% for vitamin D, 50% for potassium, 63% for fiber, and 85% for calcium, but was 115% for saturated fat and 143% for sodium. Childhood cancer survivors, in particular long-term survivors, have a poor adherence to the US dietary guidelines. © 2015 Wiley Periodicals, Inc.

Optical monitoring of shock wave-induced spreading depolarization and concomitant hypoxemia in rat brain

NASA Astrophysics Data System (ADS)

Okuda, Wataru; Kawauchi, Satoko; Ashida, Hiroshi; Sato, Shunichi; Nishidate, Izumi

2014-03-01

Blast-induced traumatic brain injury is a growing concern, but its underlying pathophysiology and mechanism are still unknown. Thus, study using an animal model is needed. We have been proposing the use of a laser-induced shock wave (LISW), whose energy is highly controllable and reproducible, to mimic blast-related injury. We previously observed the occurrence of spreading depolarization (SD) and prolonged hypoxemia in the rat brain exposed to an LISW. However, the relationship between these two events is unclear. In this study, we investigated the spatiotemporal characteristics of hypoxemia and SD to examine their correlation, for which multichannel fiber measurement and multispectral imaging of the diffuse reflectance were performed for the rat brain exposed to an LISW. We also quantified tissue oxygen saturation (StO2) in the hypoxemic phase, which is associated with possible neuronal cell death, based on an inverse Monte Carlo simulation. Fiber measurement showed that the region of hypoxemia was expanding from the site of LISW application to the distant region over the brain; the speed of expansion was similar to that of the propagation speed of SD. Simulation showed that oxygen saturation was decreased by ~40%. Multispectral imaging showed that after LISW application, a vasodilatation occurred for ~1 min, which was followed by a long-lasting vasoconstriction. In the phase of vasoconstriction, StO2 declined all over the field of view. These results indicate a strong correlation between SD and hypoxemia; the estimated StO2 seems to be low enough to induce neuronal cell death.

Dual-mode photoacoustic and ultrasound system for real-time in-vivo ovarian cancer imaging

NASA Astrophysics Data System (ADS)

Mostafa, Atahar; Nandy, Sreyankar; Amidi, Eghbal; Zhu, Quing

2018-02-01

More than 80% of the ovarian cancers are diagnosed at late stages and the survival rate is less than 50%. Currently, there is no effective screening technique available and transvaginal US can only tell if the ovaries are enlarged or not. We have developed a new real-time co-registered US and photoacoustic system for in vivo imaging and characterization of ovaries. US is used to localize ovaries and photoacoustic imaging provides functional information about ovarian tissue angiogenesis and oxygenation saturation. The system consists of a tunable laser and a commercial US system from Alpinion Inc. The Alpinion system is cable of providing channel data for both US pulse-echo and photoacoustic imaging and can be programmed as a computer terminal for display US and photoacoustic images side by side or in coregistered mode. A transvaginal ultrasound probe of 6-MHz center frequency and bandwidth of 3-10 MHz is coupled with four optical fibers surrounded the US probe to deliver the light to tissue. The light from optical fibers is homogenized to ensure the power delivered to the tissue surface is below the FDA required limit. Physicians can easily navigate the probe and use US to look for ovaries and then turn on photoacoustic mode to provide real-time tumor vasculature and So2 saturation maps. With the optimized system, we have successfully imaged first group of 7 patients of malignant, abnormal and benign ovaries. The results have shown that both photoacoustic signal strength and spatial distribution are different between malignant and abnormal and benign ovaries.

Upstream capacity upgrade in TDM-PON using RSOA based tunable fiber ring laser.

PubMed

Yi, Lilin; Li, Zhengxuan; Dong, Yi; Xiao, Shilin; Chen, Jian; Hu, Weisheng

2012-04-23

An upstream multi-wavelength shared (UMWS) time division multiplexing passive optical network (TDM-PON) is presented by using a reflective semiconductor amplifier (RSOA) and tunable optical filter (TOF) based directly modulated fiber ring laser as upstream laser source. The stable laser operation is easily achieved no matter what the bandwidth and shape of the TOF is and it can be directly modulated when the RSOA is driven at its saturation region. In this UMWS TDM-PON system, an individual wavelength can be assigned to the user who has a high bandwidth demand by tuning the central wavelength of the TOF in its upgraded optical network unit (ONU), while others maintain their traditional ONU structure and share the bandwidth via time slots, which greatly and dynamically upgrades the upstream capacity. We experimentally demonstrated the bidirectional transmission of downstream data at 10-Gb/s and upstream data at 1.25-Gb/s per wavelength over 25-km single mode fiber (SMF) with almost no power penalty at both ends. A stable performance is observed for the upstream wavelength tuned from 1530 nm to 1595 nm. Moreover, due to the high extinction ratio (ER) of the upstream signal, the burst-mode transmitting is successfully presented and a better time-division multiplexing performance can be obtained by turning off the unused lasers thanks to the rapid formation of the laser in the fiber ring. © 2012 Optical Society of America

Radiation-induced graft polymerization for the preparation of a highly efficient UHMWPE fibrous adsorbent for Cr(VI) removal

NASA Astrophysics Data System (ADS)

Gao, Qianhong; Hua, Jiangtao; Li, Rong; Xing, Zhe; Pang, Lijuan; Zhang, Mingxing; Xu, Lu; Wu, Guozhong

2017-01-01

A novel fibrous adsorbent containing amine and quaternary ammonium groups was prepared by radiation-induced graft of glycidyl methacrylate (GMA) onto ultra-high molecular weight polyethylene (UHMWPE) fiber and further modifying with triethylenetetramine (TETA) and glycidyl trimethylammonium chloride (GTA). The ATR-IR spectra and SEM observation demonstrated that amine and quaternary ammonium groups were immobilized onto the surface of UHMWPE fiber. The principal factors affecting the adsorption of Cr(VI) ions have been investigated including pH of the aqueous solution, contact time, temperature and coexisting anions. This novel fibrous adsorbent could effectively adsorb Cr(VI) in the range of pH 1-9, and the maximum adsorption capacity reached 295 mg/g at pH 3 and 25 °C based on the Langmuir isotherm. It was found that adsorption equilibrium could be achieved within 2 h for initial Cr(VI) of 100 mg/L, following the pseudo-second order model. The effect of coexisting anions (including SO42-, H2PO4-, NO3-and Cl-) on the uptake of Cr(VI) was investigated in detail. Additionally, the adsorption saturated fiber could be regenerated by soaking in 0.5 mol/L NaOH solution, and the adsorption performance of this adsorbent could be maintained at 90% after eight cycles of adsorption-desorption. ATR-IR and XPS analysis revealed that Cr(VI) ions were adsorbed on the fiber adsorbent through ion exchange mechanism.

Fluorescence Imaging Study of Extracellular Zinc at the Hippocampal Mossy Fiber Synapse

PubMed Central

Bastian, Chinthasagar; Li, Yang V

2010-01-01

Although synaptically-released, vesicular Zn2+ has been proposed to play a neuromodulatory or neuronal signaling role at the mossy fiber-CA3 synapse, Zn2+ release remains controversial, especially when detected using fluorescent imaging. In the present study, we investigated synaptically released Zn2+ at the mossy fiber synapse in rat hippocampal slices using three chemically distinct, fluorescent Zn2+ indicators. The indicators employed for this study were cell membrane impermeable (or extracellular) Newport Green (KD Zn2+ ~ 1 μM), Zinpyr-4 (KD Zn2+ ~ 1 nM) and FluoZin-3 (KD Zn2+ ~ 15 nM), chosen, in part, for their distinct dissociation constants. Among the three indicators, FluoZin-3 was also sensitive to Ca2+ (KD Ca2+ ~ 100 μM) which was present in the extracellular medium ([Ca2+]o > 2mM). Hippocampal slices loaded with either Newport Green or FluoZin-3 showed increases in fluorescence after electrical stimulation of the mossy fiber pathway. These results are consistent with previous studies suggesting the presence of synaptically-released Zn2+ in the extracellular space during neuronal activities; however, the rise in FluoZin-3 fluorescence observed was complicated by the data that the addition of exogenous Zn2+ onto FluoZin-3 loaded slices gave little change in fluorescence. In the slices loaded with the high-affinity indicator Zinpyr-4, there was little change in fluorescence after mossy fiber activation by electrical stimulation. Further study revealed that the sensitivity of Zinpyr-4 was mitigated by saturation with Zn2+ contamination from the slice. These data suggest that the sensitivity and selectivity of a probe may affect individual outcomes in a given experimental system. PMID:17485170

On the formation of noise-like pulses in fiber ring cavity configurations

NASA Astrophysics Data System (ADS)

Jeong, Yoonchan; Vazquez-Zuniga, Luis Alonso; Lee, Seungjong; Kwon, Youngchul

2014-12-01

We give an overview of the current status of fiber-based noise-like pulse (NLP) research conducted over the past decade, together with presenting the newly conducted, systematic study on their temporal, spectral, and coherence characteristics in nonlinear polarization rotation (NPR)-based erbium-doped fiber ring cavity configurations. Firstly, our study includes experimental investigations on the characteristic features of NLPs both in the net anomalous dispersion regime and in the net normal dispersion regime, in comparison with coherent optical pulses that can alternatively be obtained from the same cavity configurations, i.e., with the conventional and dissipative solitons. Secondly, our study includes numerical simulations on the formation of NLPs, utilizing a simplified, scalar-field model based on the characteristic transfer function of the NPR mechanism in conjunction with the split-step Fourier algorithm, which offer a great help in exploring the interrelationship between the NLP formation and various cavity parameters, and eventually present good agreement with the experimental results. We stress that if the cavity operates with excessively high gain, i.e., higher than the levels just required for generating coherent mode-locked pulses, i.e., conventional solitons and dissipative solitons, it may trigger NLPs, depending on the characteristic transfer function of the NPR mechanism induced in the cavity. In particular, the NPR transfer function is characterized by the critical saturation power and the linear loss ratio. Finally, we also report on the applications of the fiber-based NLP sources, including supercontinuum generation in a master-oscillator power amplifier configuration seeded by a fiber-based NLP source, as one typical example. We expect that the NLP-related research area will continue to expand, and that NLP-based sources will also find more applications in the future.

Familial hypertrophic cardiomyopathy: functional effects of myosin mutation R723G in cardiomyocytes.

PubMed

Kraft, Theresia; Witjas-Paalberends, E Rosalie; Boontje, Nicky M; Tripathi, Snigdha; Brandis, Almuth; Montag, Judith; Hodgkinson, Julie L; Francino, Antonio; Navarro-Lopez, Francisco; Brenner, Bernhard; Stienen, Ger J M; van der Velden, Jolanda

2013-04-01

Familial Hypertrophic Cardiomyopathy (FHC) is frequently caused by mutations in the β-cardiac myosin heavy chain (β-MyHC). To identify changes in sarcomeric function triggered by such mutations, distinguishing mutation effects from other functional alterations of the myocardium is essential. We previously identified a direct effect of mutation R723G (MyHC723) on myosin function in slow Musculus soleus fibers. Here we investigate contractile features of left ventricular cardiomyocytes of FHC-patients with the same MyHC723-mutation and compare these to the soleus data. In mechanically isolated, triton-permeabilized MyHC723-cardiomyocytes, maximum force was significantly lower but calcium-sensitivity was unchanged compared to donor. Conversely, MyHC723-soleus fibers showed significantly higher maximum force and reduced calcium-sensitivity compared to controls. Protein phosphorylation, a potential myocardium specific modifying mechanism, might account for differences compared to soleus fibers. Analysis revealed reduced phosphorylation of troponin I and T, myosin-binding-protein C, and myosin-light-chain 2 in MyHC723-myocardium compared to donor. Saturation of protein-kinaseA phospho-sites led to comparable, i.e., reduced MyHC723-calcium-sensitivity in cardiomyocytes as in M. soleus fibers, while maximum force remained reduced. Myofibrillar disarray and lower density of myofibrils, however, largely account for reduced maximum force in MyHC723-cardiomyocytes. The changes seen when phosphorylation of sarcomeric proteins in myocardium of affected patients is matched to control tissue suggest that the R723G mutation causes reduced Ca(++)-sensitivity in both cardiomyocytes and M. soleus fibers. In MyHC723-myocardium, however, hypophosphorylation can compensate for the reduced calcium-sensitivity, while maximum force generation, lowered by myofibrillar deficiency and disarray, remains impaired, and may only be compensated by hypertrophy. Copyright © 2013 Elsevier Ltd. All rights reserved.

High-Power Fiber Lasers Using Photonic Band Gap Materials

NASA Technical Reports Server (NTRS)

DiDomenico, Leo; Dowling, Jonathan

2005-01-01

High-power fiber lasers (HPFLs) would be made from photonic band gap (PBG) materials, according to the proposal. Such lasers would be scalable in the sense that a large number of fiber lasers could be arranged in an array or bundle and then operated in phase-locked condition to generate a superposition and highly directed high-power laser beam. It has been estimated that an average power level as high as 1,000 W per fiber could be achieved in such an array. Examples of potential applications for the proposed single-fiber lasers include welding and laser surgery. Additionally, the bundled fibers have applications in beaming power through free space for autonomous vehicles, laser weapons, free-space communications, and inducing photochemical reactions in large-scale industrial processes. The proposal has been inspired in part by recent improvements in the capabilities of single-mode fiber amplifiers and lasers to produce continuous high-power radiation. In particular, it has been found that the average output power of a single strand of a fiber laser can be increased by suitably changing the doping profile of active ions in its gain medium to optimize the spatial overlap of the electromagnetic field with the distribution of active ions. Such optimization minimizes pump power losses and increases the gain in the fiber laser system. The proposal would expand the basic concept of this type of optimization to incorporate exploitation of the properties (including, in some cases, nonlinearities) of PBG materials to obtain power levels and efficiencies higher than are now possible. Another element of the proposal is to enable pumping by concentrated sunlight. Somewhat more specifically, the proposal calls for exploitation of the properties of PBG materials to overcome a number of stubborn adverse phenomena that have impeded prior efforts to perfect HPFLs. The most relevant of those phenomena is amplified spontaneous emission (ASE), which causes saturation of gain and power at undesirably low levels, and scattering of light from dopants. In designing a given fiber laser for reduced ASE, care must be taken to maintain a correct fiber structure for eventual scaling to an array of many such lasers such that the interactions among all the members of the array would cause them to operate in phase lock. Hence, the problems associated with improving a single-fiber laser are not entirely separate from the bundling problem, and some designs for individual fiber lasers may be better than others if the fibers are to be incorporated into bundles. Extensive calculations, expected to take about a year, must be performed in order to determine design parameters before construction of prototype individual and fiber lasers can begin. The design effort can be expected to include calculations to optimize overlaps between the electromagnetic modes and the gain media and calculations of responses of PBG materials to electromagnetic fields. Design alternatives and physical responses that may be considered include simple PBG fibers with no intensity-dependent responses, PBG fibers with intensity- dependent band-gap shifting (see figure), and broad-band pumping made possible by use of candidate broad-band pumping media in place of the air or vacuum gaps used in prior PBG fibers.

Assessment of commercial optical amplifiers for potential use in space applications

NASA Astrophysics Data System (ADS)

Barbero, Juan; Sotom, Michel; Benazet, Benoit; Esquivias, Ignacio; López Hernández, Francisco José

2017-11-01

This paper describes the activities and results of an ESA-funded project concerned with the assessment of optical amplifier technologies and products for applications in fiber optic subsystems of future satellite payloads. On-board applications are briefly introduced, together with associated system-level requirements. Optical amplifier technologies, research achievements and products are reviewed. They are compared in terms of current performance, perspectives and suitability for the target space applications. Optical fibre amplifiers, not limited to Erbium-doped amplifiers, Erbium-doped waveguide amplifiers and Semiconductor Optical Amplifiers are covered. The review includes analysis and trade-off of all performance parameters including saturation output power, noise figure, polarisation maintaining capability, wall-plug efficiency, and mass and size. A selection of optical amplifier products for further evaluation and testing is presented. Results of extensive testing covering both functional performance and environmental behaviour (mechanical, thermal vacuum, radiations) aspects are reported. Most of the work has been completed, but an extension has been proposed for checking and comparing the behaviour of doped fibers under gamma radiation.

Eight-channel time-resolved tissue oximeter for functional muscle studies

NASA Astrophysics Data System (ADS)

Cubeddu, Rinaldo; Biscotti, Giovanni; Pifferi, Antonio; Taroni, Paola; Torricelli, Alessandro; Ferrari, Marco; Quaresima, Valentina

2003-07-01

A portable instrument for tissue oximetry based on time-resolved reflectance spectroscopy was developed. The output pulses of 2 laser diodes (683 and 785 nm, 80 MHz pulse repetition rate, 1 mW average power, 100 ps FWHM) are delayed and coupled into a multimode graded-index fiber (50/125 μm and injected into the tissue. The reflectance photons are collected by 8 independent 1 mm fibers and detected by a 16-anode photomultiplier. A time-correlated single photon counting PC board is used for the parallel acquisition of the curves. Simultaneous estimate of the transport scattering and absorption coefficients is achieved by best fitting of time-resolved reflectance curves with a standard model of Diffusion Theory. The performances of the system were tested on phantoms in terms of stability, reproducibility among channels, and accuracy in the determination of the optical properties. Preliminary in vivo measurements were performed on healthy volunteers to monitor spatial changes in calf (medical and lateral gastrocnemius) oxygen hemoglobin saturation and blood volume during dynamic plantar flexion exercise.

Dietary Composition Independent of Weight Loss in the Management of Non-Alcoholic Fatty Liver Disease

PubMed Central

Eslamparast, Tannaz; Tandon, Puneeta; Raman, Maitreyi

2017-01-01

Poor dietary composition is an important factor in the progression of non-alcoholic fatty liver disease (NAFLD). The majority of NAFLD patients follow diets with overconsumption of simple carbohydrates, total and saturated fat, with reduced intake of dietary fiber and omega-3 rich foods. Although lifestyle modifications including weight loss and exercise remain the keystone of NAFLD management, modifying dietary composition with or without a calorie-restricted diet may also be a feasible and sustainable strategy for NAFLD treatment. In the present review article, we highlight the potential therapeutic role of a “high quality healthy diet” to improve hepatic steatosis and metabolic dysfunction in patients with NAFLD, independent of caloric restriction and weight loss. We provide a literature review evaluating the evidence behind dietary components including fiber-, meat- and omega-3-rich diets and, pending further evidence, we concur with the EASL-EASD-EASO Clinical Guidelines recommendation of the Mediterranean diet as the diet of choice in these patients. PMID:28933748

Broadband photon-photon interactions mediated by cold atoms in a photonic crystal fiber

PubMed Central

Litinskaya, Marina; Tignone, Edoardo; Pupillo, Guido

2016-01-01

We demonstrate theoretically that photon-photon attraction can be engineered in the continuum of scattering states for pairs of photons propagating in a hollow-core photonic crystal fiber filled with cold atoms. The atoms are regularly spaced in an optical lattice configuration and the photons are resonantly tuned to an internal atomic transition. We show that the hard-core repulsion resulting from saturation of the atomic transitions induces bunching in the photonic component of the collective atom-photon modes (polaritons). Bunching is obtained in a frequency range as large as tens of GHz, and can be controlled by the inter-atomic separation. We provide a fully analytical explanation for this phenomenon by proving that correlations result from a mismatch of the quantization volumes for atomic excitations and photons in the continuum. Even stronger correlations can be observed for in-gap two-polariton bound states. Our theoretical results use parameters relevant for current experiments and suggest a simple and feasible way to induce interactions between photons. PMID:27170160

Mode-locking evolution in ring fiber lasers with tunable repetition rate.

PubMed

Korobko, D A; Fotiadi, A A; Zolotovskii, I O

2017-09-04

We have applied a simple approach to analyze behavior of the harmonically mode-locked fiber laser incorporating an adjustable Mach-Zehnder interferometer (MZI). Our model is able to describe key features of the laser outputs and explore limitations of physical mechanisms responsible for laser operation at different pulse repetition rates tuned over a whole GHz range. At low repetition rates the laser operates as a harmonically mode-locked soliton laser triggered by a fast saturable absorber. At high repetition rates the laser mode-locking occurs due to dissipative four-wave mixing seeded by MZI and gain spectrum filtering. However, the laser stability in this regime is rather low due to poor mode selectivity provided by MZI that is able to support the desired laser operation just near the lasing threshold. The use of a double MZI instead of a single MZI could improve the laser stability and extends the range of the laser tunability. The model predicts a gap between two repetitive rate ranges where pulse train generation is not supported.

Development of a real-time and quantitative thrombus sensor for an extracorporeal centrifugal blood pump by near-infrared light

PubMed Central

Sakota, Daisuke; Fujiwara, Tatsuki; Ohuchi, Katsuhiro; Kuwana, Katsuyuki; Yamazaki, Hiroyuki; Kosaka, Ryo; Nishida, Masahiro; Mizuno, Tomohiro; Arai, Hirokuni; Maruyama, Osamu

2017-01-01

We developed an optical thrombus sensor for a monopivot extracorporeal centrifugal blood pump. In this study, we investigated its quantitative performance for thrombus detection in acute animal experiments of left ventricular assist using the pump on pathogen-free pigs. Optical fibers were set in the driver unit of the pump. The incident light at the near-infrared wavelength of 810 nm was aimed at the pivot bearing, and the resulting scattered light was guided to the optical fibers. The detected signal was analyzed to obtain the thrombus formation level. As a result, real-time and quantitative monitoring of the thrombus surface area on the pivot bearing was achieved with an accuracy of 3.6 ± 2.3 mm2. In addition, the sensing method using the near-infrared light was not influenced by changes in the oxygen saturation and the hematocrit. It is expected that the developed sensor will be useful for optimal anticoagulation management for long-term extracorporeal circulation therapies. PMID:29359096

Development of a real-time and quantitative thrombus sensor for an extracorporeal centrifugal blood pump by near-infrared light.

PubMed

Sakota, Daisuke; Fujiwara, Tatsuki; Ohuchi, Katsuhiro; Kuwana, Katsuyuki; Yamazaki, Hiroyuki; Kosaka, Ryo; Nishida, Masahiro; Mizuno, Tomohiro; Arai, Hirokuni; Maruyama, Osamu

2018-01-01

We developed an optical thrombus sensor for a monopivot extracorporeal centrifugal blood pump. In this study, we investigated its quantitative performance for thrombus detection in acute animal experiments of left ventricular assist using the pump on pathogen-free pigs. Optical fibers were set in the driver unit of the pump. The incident light at the near-infrared wavelength of 810 nm was aimed at the pivot bearing, and the resulting scattered light was guided to the optical fibers. The detected signal was analyzed to obtain the thrombus formation level. As a result, real-time and quantitative monitoring of the thrombus surface area on the pivot bearing was achieved with an accuracy of 3.6 ± 2.3 mm 2 . In addition, the sensing method using the near-infrared light was not influenced by changes in the oxygen saturation and the hematocrit. It is expected that the developed sensor will be useful for optimal anticoagulation management for long-term extracorporeal circulation therapies.

Catalytic Effect of Activated Carbon and Activated Carbon Fiber in Non-Equilibrium Plasma-Based Water Treatment

NASA Astrophysics Data System (ADS)

Zhang, Yanzong; Zheng, Jingtang; Qu, Xianfeng; Yu, Weizhao; Chen, Honggang

2008-06-01

Catalysis and regeneration efficiency of granular activated carbon (GAC) and activated carbon fiber (ACF) were investigated in a non-equilibrium plasma water treatment reactor with a combination of pulsed streamer discharge and GAC or ACF. The experimental results show that the degradation efficiency of methyl orange (MO) by the combined treatment can increase 22% (for GAC) and 24% (for ACF) respectively compared to pulsed discharge treatment alone, indicating that the combined treatment has a synergetic effect. The MO degradation efficiency by the combined treatment with pulsed discharge and saturated GAC or ACF can increase 12% and 17% respectively compared to pulsed discharge treatment alone. Both GAC and ACF show catalysis and the catalysis of ACF is prominent. Meanwhile, the regeneration of GAC and ACF are realized in this process. When H2O2 is introduced into the system, the utilization efficiency of ozone and ultraviolet light is improved and the regeneration efficiency of GAC and ACF is also increased.

All-optical gain-clamped wideband serial EDFA with ring-shaped laser

NASA Astrophysics Data System (ADS)

Lu, Yung-Hsin; Chi, Sien

2004-01-01

We experimentally investigate the static and dynamic properties of all-optical gain-clamped wideband (1530-1600 nm) serial erbium-doped fiber amplifier with a single ring-shaped laser, which consists of a circulator and a fiber Bragg grating at the output end. The lasing light passing through the second stage is intentionally blocked at the output end by a C/L-band wavelength division multiplexer owning the huge insertion loss, and thus, the copropagating ring-laser light is formed by the first stage. This design can simultaneously clamp the gains of 1547 and 1584 nm probes near 14 dB and shows the same dynamic range of input power up to -4 dBm for conventional band and long-wavelength band. Furthermore, the transient responses of 1551 and 1596 nm surviving channels exhibit small power excursions (<0.54 dB) as the total saturating tone with -2 dBm is modulated on and off at 270 Hz.

Effect of fiber sources on fatty acids profile, glycemic index, and phenolic compound content of in vitro digested fortified wheat bread.

PubMed

Kurek, Marcin Andrzej; Wyrwisz, Jarosław; Karp, Sabina; Wierzbicka, Agnieszka

2018-05-01

In this study, some dietary fiber (DF) sources were investigated as fortifiers of wheat bread: oat (OB), flax (FB), and apple (AB). Adding oat and flax fibers to bread significantly changed the fatty acid profiles. OB was highest in oleic acid (33.83% of lipids) and linoleic acid (24.31% of lipids). Only in FB, γ-linolenic fatty acid was present in a significant amount-18.32%. The bioaccessibility trails revealed that the DF slow down the intake of saturated fatty acids. PUFA were least bioaccessible from all fatty acids groups in the range of (72% in OB to 87% in FB). The control bread had the greatest value (80.5) and was significantly higher than values for OB, FB, and AB in terms of glycemic index. OB, FB and AB addition led to obtain low glycemic index. AB had a significant highest value of total phenolic (897.2 mg/kg) with the lowest values in FB (541.2 mg/kg). The only significant lowering of caloric values in this study was observed in AB. The study could address the gap in the area of research about taking into consideration glycemic index, fatty acid profile and phenolic content in parallel in terms of DF application in breads.

The use of neural networks and texture analysis for rapid objective selection of regions of interest in cytoskeletal images.

PubMed

Derkacs, Amanda D Felder; Ward, Samuel R; Lieber, Richard L

2012-02-01

Understanding cytoskeletal dynamics in living tissue is prerequisite to understanding mechanisms of injury, mechanotransduction, and mechanical signaling. Real-time visualization is now possible using transfection with plasmids that encode fluorescent cytoskeletal proteins. Using this approach with the muscle-specific intermediate filament protein desmin, we found that a green fluorescent protein-desmin chimeric protein was unevenly distributed throughout the muscle fiber, resulting in some image areas that were saturated as well as others that lacked any signal. Our goal was to analyze the muscle fiber cytoskeletal network quantitatively in an unbiased fashion. To objectively select areas of the muscle fiber that are suitable for analysis, we devised a method that provides objective classification of regions of images of striated cytoskeletal structures into "usable" and "unusable" categories. This method consists of a combination of spatial analysis of the image using Fourier methods along with a boosted neural network that "decides" on the quality of the image based on previous training. We trained the neural network using the expert opinion of three scientists familiar with these types of images. We found that this method was over 300 times faster than manual classification and that it permitted objective and accurate classification of image regions.

Cholesterol Bilayer Domains in the Eye Lens Health: A Review.

PubMed

Widomska, Justyna; Subczynski, Witold K; Mainali, Laxman; Raguz, Marija

2017-12-01

The most unique biochemical characteristic of the eye lens fiber cell plasma membrane is its extremely high cholesterol content, the need for which is still unclear. It is evident, however, that the disturbance of Chol homeostasis may result in damages associated with cataracts. Electron paramagnetic resonance methods allow discrimination of two types of lipid domains in model membranes overloaded with Chol, namely, phospholipid-cholesterol domains and pure Chol bilayer domains. These domains are also detected in human lens lipid membranes prepared from the total lipids extracted from lens cortices and nuclei of donors from different age groups. Independent of the age-related changes in phospholipid composition, the physical properties of phospholipid-Chol domains remain the same for all age groups and are practically identical for cortical and nuclear membranes. The presence of Chol bilayer domains in these membranes provides a buffering capacity for cholesterol concentration in the surrounding phospholipid-Chol domains, keeping it at a constant saturating level and thus keeping the physical properties of the membrane consistent with and independent of changes in phospholipid composition. It seems that the presence of Chol bilayer domains plays an integral role in the regulation of cholesterol-dependent processes in fiber cell plasm membranes and in the maintenance of fiber cell membrane homeostasis.

Versatile soliton emission from a WS2 mode-locked fiber laser

NASA Astrophysics Data System (ADS)

Guo, Bo; Li, Shi; Fan, Ya-xian; Wang, Pengfei

2018-01-01

Recently, few-layer tungsten disulfide (WS2), as a shining 2D material, has been discovered to possess both the saturable absorption ability and large nonlinear refractive index. Here, we demonstrate versatile soliton pulses in a passively mode-locked fiber laser with a WS2-deposited microfiber. The few-layer WS2 is prepared by the liquid-phase exfoliation method and transferred onto a microfiber by the optical deposition method. Study found, the WS2-deposited microfiber can operate simultaneously as a mode-locker and a high-nonlinear device. In experiment, by further inserting the WS2 device into the fiber laser, besides the dual-wavelength soliton, noise-like soliton pulse, conventional soliton and its harmonic form are obtained by properly adjusting the pump strength and the polarization states. For the dual-wavelength soliton pulses and noise-like pulse, the maximum output power of 14.2 mW and pulse energy of 4.74 nJ is obtained, respectively. In addition, we also achieve the maximum harmonic number (135) of conventional soliton, corresponding to a repetition rate of ∼ 497 . 5 MHz. Our study shows clearly that WS2-deposited microfiber can be as a high-nonlinear photonic device for studying a plenty of nonlinear soliton phenomena.

Microstructure and Texture Development during Cold Rolling in UNS S32205 and UNS S32760 Duplex Stainless Steels

NASA Astrophysics Data System (ADS)

Kumar, Amit; Khatirkar, Rajesh Kisni; Chalapathi, Darshan; Kumar, Gulshan; Suwas, Satyam

2017-05-01

In the present study, microstructure and texture evolution during cold rolling in UNS S32205 and UNS S32760 duplex stainless steel was investigated. Both steels were unidirectionally cold rolled up to 80 pct thickness reduction. Scanning electron microscopy and electron backscattered diffraction (EBSD) were used for microstructural characterization, while X-ray diffraction (XRD) was used for the measurement of bulk texture. Strain-induced martensite (SIM) was identified and quantified with the help of magnetic measurements (B-H curve and magnetization saturation). With the increase in plastic strain, the grains became morphologically elongated along the rolling direction with the reduction in average band thickness and band spacing. SIM increased with the increase in deformation and was found to be a function of strain and the SFE of austenite. The increase in SIM was much more pronounced in UNS S32205 steel as compared to UNS S32760 steel. After cold rolling, strong α-fiber (RD//<110>) texture was developed in ferrite, while brass texture was dominant in austenite for both steels. The strength of texture components and fibers was stronger in UNS S32760 steel. Another significant feature was the development of weak γ-fiber (ND//<111>) in UNS S32760 steel at intermediate deformation.

Optimisation of cascaded Yb fiber amplifier chains using numerical-modelling

NASA Astrophysics Data System (ADS)

He, F.; Price, J. H.; Vu, K. T.; Malinowski, A.; Sahu, J. K.; Richardson, D. J.

2006-12-01

We show that it is possible to adapt existing software packages developed originally for modeling telecommunication devices and systems to reliably predict and optimize the performance of high-power Ytterbium-doped fiber amplifier and laser systems. The ready availability of a flexible, user-friendly design tool should be of considerable practical interest to scientists and engineers working with this important new laser technology since Ytterbium amplifier and amplifier cascades are often difficult to optimize experimentally due to the three-level nature of the Ytterbium laser transition. As examples of the utility and accuracy of the software, as well as the complexity of the systems and amplifier properties that can be successfully modeled, we present a comparison of experimental and theoretical results for individual core and cladding pumped amplifiers, and also for an ultra-short pulse four-stage amplifier system optimized both to provide a broad gain bandwidth and to minimize nonlinear effects. We also show how high energy 100 ns pulses with complex user definable temporal profiles can be created in a gain-saturated amplifier by suitable pre-shaping of the low-energy input pulses. Furthermore, with appropriate modifications the same software package can be applied to fiber amplifiers based on other rare-earth elements and glass hosts.

Vector solitons in a laser passively mode-locked by single-wall carbon nanotubes

NASA Astrophysics Data System (ADS)

Wong, Jia Haur; Wu, Kan; Liu, Huan Huan; Ouyang, Chunmei; Wang, Honghai; Aditya, Sheel; Shum, Ping; Fu, Songnian; Kelleher, E. J. R.; Chernov, A.; Obraztsova, E. D.

2011-04-01

Polarization Rotation Locked Vector Solitons (PRLVSs) are experimentally observed for the first time in a fiber ring laser passively mode-locked by a single-wall carbon nanotube (SWCNT) saturable absorber. Period-doubling of these solitons at certain birefringence values has also been observed. We show that fine adjustment to the intracavity birefringence can swing the PRLVSs from period-doubled to period-one state without simultaneous reduction in the pump strength. The timing jitter for both states has also been measured experimentally and discussed analytically using the theoretical framework provided by the Haus model.

Structure and Electrochemistry of Copper Fluoride Nanocomposites Utilizing Mixed Conducting Matrices

DTIC Science & Technology

2007-01-01

similar to the conversion reaction of the metal fluoride. Attractive materials such as V2O5 , MoS2, and MoO3-δ can be utilized. Examples of metal...fluorides enabled by these MCM matrices are nanocomposites of FeF3 ( V2O5 ),2 BiF3 (MoS2),15 and as discussed herein, CuF2 (MoO3). In all cases, the...filled dry box using Whatman GF/D glass fiber separators saturated with 1M LiPF6 in 1:1 vol/vol ethylene carbonate:dimethyl carbonate elec- trolyte

New technique for simulation of optical fiber amplifiers control schemes in dynamic WDM systems

NASA Astrophysics Data System (ADS)

Freitas, Marcio; Klein, Jackson; Givigi, Sidney, Jr.; Calmon, Luiz C.

2005-04-01

One topic that has attracted attention is related to the behavior of the optical amplifiers under dynamic conditions, specifically because amplifiers working in a saturated condition produce power transients in all-optical reconfigurable WDM networks, e.g. adding/dropping channels. The goal of this work is to introduce the multiwavelength time-driven simulations technique, capable of simulation and analysis of transient effects in all-optical WDM networks with optical amplifiers, and allow the use of control schemes to avoid or minimize the impacts of transient effects in the system performance.

Remember when mom wanted you home for dinner?

PubMed

Stockmyer, C

2001-02-01

Limited information exists about the relationship between family dinner and the quality of children's diets. However, several studies suggest that foods obtained at home have more fiber, calcium, and iron, and less total fat, saturated fat, cholesterol, and sodium than foods obtained away from home. The results of a recent study confirm and extend these observations by showing beneficial effects of family dinner on the diet quality of children ages 9 to 14. Nutritionists and health educators should look for ways to encourage families to increase the number of meals eaten together to improve the eating patterns of children.

Use of 2,5-dimethyl-2,5-hexane diamine as a curing agent for epoxy resins

DOEpatents

Rinde, J.A.; Newey, H.A.

1981-02-24

Primary diamines are disclosed of the formula shown in a diagram wherein R is a straight chain saturated hydrocarbon of 2 to 4 carbons, a disubstituted benzene ring, or disubstituted dibenzomethane for use as a curing agent for epoxy resins. These curing agents can be used to form epoxy resin mixtures useful in filament winding and pre-impregnated fiber molding and in formulating film adhesives, powder coatings and molding powders. The epoxy mixtures form for such uses as room temperature non-reacting, intermediate stable state which has a latent cross-linking capability.

Use of 2,5-dimethyl-2,5-hexane diamine as a curing agent for epoxy resins

DOEpatents

Rinde, James A. [Livermore, CA; Newey, Herbert A. [Lafayette, CA

1981-02-24

Primary diamines of the formula ##STR1## wherein R is a straight chain saturated hydrocarbon of 2 to 4 carbons, a disubstituted benzene ring, or disubstituted dibenzo methane for use as a curing agent for epoxy resins. These curing agents can be used to form epoxy resin mixtures useful in filament winding and pre-impregnated fiber molding and in formulating film adhesives, powder coatings and molding powders. The epoxy mixtures form for such uses as room temperature non-reacting, intermediate stable state which has a latent cross-linking capability.

The share of ultra-processed foods and the overall nutritional quality of diets in the US: evidence from a nationally representative cross-sectional study.

PubMed

Martínez Steele, Euridice; Popkin, Barry M; Swinburn, Boyd; Monteiro, Carlos A

2017-02-14

Recent population dietary studies indicate that diets rich in ultra-processed foods, increasingly frequent worldwide, are grossly nutritionally unbalanced, suggesting that the dietary contribution of these foods largely determines the overall nutritional quality of contemporaneous diets. Yet, these studies have focused on individual nutrients (one at a time) rather than the overall nutritional quality of the diets. Here we investigate the relationship between the energy contribution of ultra-processed foods in the US diet and its content of critical nutrients, individually and overall. We evaluated dietary intakes of 9,317 participants from 2009 to 2010 NHANES aged 1+ years. Food items were classified into unprocessed or minimally processed foods, processed culinary ingredients, processed foods, and ultra-processed foods. First, we examined the average dietary content of macronutrients, micronutrients, and fiber across quintiles of the energy contribution of ultra-processed foods. Then, we used Principal Component Analysis (PCA) to identify a nutrient-balanced dietary pattern to enable the assessment of the overall nutritional quality of the diet. Linear regression was used to explore the association between the dietary share of ultra-processed foods and the balanced-pattern PCA factor score. The scores were thereafter categorized into tertiles, and their distribution was examined across ultra-processed food quintiles. All models incorporated survey sample weights and were adjusted for age, sex, race/ethnicity, family income, and educational attainment. The average content of protein, fiber, vitamins A, C, D, and E, zinc, potassium, phosphorus, magnesium, and calcium in the US diet decreased significantly across quintiles of the energy contribution of ultra-processed foods, while carbohydrate, added sugar, and saturated fat contents increased. An inverse dose-response association was found between ultra-processed food quintiles and overall dietary quality measured through a nutrient-balanced-pattern PCA-derived factor score characterized by being richer in fiber, potassium, magnesium and vitamin C, and having less saturated fat and added sugars. This study suggests that decreasing the dietary share of ultra-processed foods is a rational and effective way to improve the nutritional quality of US diets.

Fundamental studies of MALDI with an orthogonal TOF mass spectrometer

NASA Astrophysics Data System (ADS)

Qiao, Hui

The interaction between the matrix and analyte molecules are studied with a high resolution MALDI imaging technique in an orthogonal-injection time of flight (TOF) mass spectrometer. The analyte incorporation and distribution patterns have been clearly demonstrated. Purified protein analytes were found to be homogeneously incorporated in large single crystals of DHB and sinapinic acid matrices, with no evidence for preferred crystal faces. Segregation of some species was observed and appeared to correlate with analyte hydrophobicity, and to a lesser extent analyte mass or mobility. Similar segregation phenomena were observed with confocal laser scanning microscopy of the same analytes labeled with fluorescent dyes in 2,5-DHB single crystals. The above investigations may shed some light on optimizing sample preparation with different matrices. The influence of incident laser parameters on sensitivity in MALDI has been investigated using orthogonal-injection TOF instruments. A qualitative comparison was first made between the beam profiles obtained with a N 2 laser and a Nd:YAG laser using 2-m long optical fibers. The N 2 laser gives better sensitivity, consistent with a more uniform fluence distribution and therefore better coverage of the N2 laser profile. Most of the difference disappears when a 30-m long fiber is used or when the fibers are twisted during irradiation to smooth out the fluence distribution. In more systematic measurements, the total integrated ion yield from a single spot (a measure of sensitivity) was found to increase rapidly with fluence to a maximum, and then saturate or decrease slightly. Thus, the optimum sensitivity is achieved at high fluence. For a fluence near threshold, the integrated yield has a steep (cubic) dependence on the spot size, but the yield saturates at higher fluence for smaller spots. The area dependence is much weaker (close to linear) for fluence values above saturation, with the result that the highest integrated yields per unit area are obtained with the smallest spot sizes. The results have particular relevance for imaging MALDI, where sensitivity and spatial resolution are important figures of merit. Finally the detection properties of the MCP detector were studied with a hybrid MCP and CuBe venetian blind converter detector. The measurements show that the detection efficiency of the MCP drops with the increasing of ion mass and the decreasing of the ion energy. For transferrin (79,500 Da), the relative detection efficiency of the MCP is about 40% at 10.6 keV and it decreases to about 5% at 4.6 keV. The secondary electron emission coefficient of the MCP shows a linear dependence on mass and a power law dependence on velocity (˜3.2). No clear velocity threshold is observed for secondary electron emission.

Module for Oxygenating Water without Generating Bubbles

NASA Technical Reports Server (NTRS)

Gonzalez-Martin, Anuncia; Sidik, Reyimjan; Kim, Jinseong

2004-01-01

A module that dissolves oxygen in water at concentrations approaching saturation, without generating bubbles of oxygen gas, has been developed as a prototype of improved oxygenators for water-disinfection and water-purification systems that utilize photocatalyzed redox reactions. Depending on the specific nature of a water-treatment system, it is desirable to prevent the formation of bubbles for one or more reasons: (1) Bubbles can remove some organic contaminants from the liquid phase to the gas phase, thereby introducing a gas-treatment problem that complicates the overall water-treatment problem; and/or (2) in some systems (e.g., those that must function in microgravity or in any orientation in normal Earth gravity), bubbles can interfere with the flow of the liquid phase. The present oxygenation module (see Figure 1) is a modified version of a commercial module that contains >100 hollow polypropylene fibers with a nominal pore size of 0.05 m and a total surface area of 0.5 m2. The module was originally designed for oxygenation in a bioreactor, with no water flowing around or inside the tubes. The modification, made to enable the use of the module to oxygenate flowing water, consisted mainly in the encapsulation of the fibers in a tube of Tygon polyvinyl chloride (PVC) with an inside diameter of 1 in. (approx.=25 mm). In operation, water is pumped along the insides of the hollow fibers and oxygen gas is supplied to the space outside the hollow tubes inside the PVC tube. In tests, the pressure drops of water and oxygen in the module were found to be close to zero at water-flow rates ranging up to 320 mL/min and oxygen-flow rates up to 27 mL/min. Under all test conditions, no bubbles were observed at the water outlet. In some tests, flow rates were chosen to obtain dissolved-oxygen concentrations between 25 and 31 parts per million (ppm) . approaching the saturation level of approx.=35 ppm at a temperature of 20 C and pressure of 1 atm (approx.=0.1 MPa). As one would expect, it was observed that the time needed to bring a flow of water from an initial low dissolved-oxygen concentration (e.g., 5 ppm) to a steady high dissolved-oxygen concentration at or near the saturation level depends on the rates of flow of both oxygen and water, among other things. Figure 2 shows the results of an experiment in which a greater flow of oxygen was used during the first few tens of minutes to bring the concentration up to approx.=25 ppm, then a lesser flow was used to maintain the concentration.

Influence of the addition of soy product and wheat fiber on rheological, textural, and other quality characteristics of pizza.

PubMed

Glicerina, Virginia; Balestra, Federica; Capozzi, Francesco; Dalla Rosa, Marco; Romani, Santina

2017-11-17

The effect of partial replacement of wheat flour with soy paste and wheat fiber on rheological, textural, physicochemical, and organoleptic characteristics of an enriched pizza base (E) was investigated in comparison with those of a control pizza base (C). New ingredients (e.g., enriched cooked ham, whey cheese, and tomato sauce realized using food industry by-products) were also used in E pizza topping to further increase its nutritional properties. Enriched dough was developed first at a laboratory level. Large and small deformation, moisture, leavening activity, and metabolic heat were tested. On the final product, produced at the industrial level, textural, color, sensory, and nutritional analyses were performed. Preliminary rheological analysis was essential to evaluate the suitability of the new pizza to be processed at industrial level. Both pizza dough samples showed a solid elastic-like behavior; however, the addition of soy and fiber increased moisture content of E pizza, due to the water binding ability of soy protein and to the effect of fibers that also decreased E dough elasticity. No differences in extensibility between the two samples were observed, whereas significantly lower values of resistance to extension and dough force were shown in sample E. These differences were likely due to the presence of soy that interfere with gluten formation and to the dietary fibers that interact with water. Ingredients used in E pizza improved its nutritional quality increasing dietary fibers and protein, and decreasing saturated fatty acids and cholesterol content, which contributed to decrease energy value, in terms of kilocalorie reduction. In this work, the effects of using new ingredients (e.g., soy paste, wheat fiber) on the rheological, textural, physicochemical, nutritional, and organoleptic characteristics of an enriched pizza type were investigated both at laboratory and industrial levels. The new pizza provides a product that combines solid technological performances, in terms of rheological properties and dough elasticity, with improved and balanced nutritional quality, thanks also to the ingredients used in the topping. Results demonstrate the possibility of obtaining new pizza products characterized by nutritional and sensorial properties tailored for different group of consumers. © 2017 Wiley Periodicals, Inc.

Near-infrared spectroscopy of renal tissue in vivo

NASA Astrophysics Data System (ADS)

Grosenick, Dirk; Steinkellner, Oliver; Wabnitz, Heidrun; Macdonald, Rainer; Niendorf, Thoralf; Cantow, Kathleen; Flemming, Bert; Seeliger, Erdmann

2013-03-01

We have developed a method to quantify hemoglobin concentration and oxygen saturation within the renal cortex by near-infrared spectroscopy. A fiber optic probe was used to transmit the radiation of three semiconductor lasers at 690 nm, 800 nm and 830 nm to the tissue, and to collect diffusely remitted light at source-detector separations from 1 mm to 4 mm. To derive tissue hemoglobin concentration and oxygen saturation of hemoglobin the spatial dependence of the measured cw intensities was fitted by a Monte Carlo model. In this model the tissue was assumed to be homogeneous. The scaling factors between measured intensities and simulated photon flux were obtained by applying the same setup to a homogeneous semi-infinite phantom with known optical properties and by performing Monte Carlo simulations for this phantom. To accelerate the fit of the tissue optical properties a look-up table of the simulated reflected intensities was generated for the needed range of absorption and scattering coefficients. The intensities at the three wavelengths were fitted simultaneously using hemoglobin concentration, oxygen saturation, the reduced scattering coefficient at 800 nm and the scatter power coefficient as fit parameters. The method was employed to study the temporal changes of renal hemoglobin concentration and blood oxygenation on an anesthetized rat during a short period of renal ischemia induced by aortic occlusion and during subsequent reperfusion.

Dietary Fats and Oils in India.

PubMed

Gulati, Seema; Misra, Anoop; Sharma, Meenu

2017-01-01

India is undergoing rapid nutrition transition concurrent with an increase in obesity, metabolic syndrome, and type 2 diabetes (T2DM). There is a shift from a healthy traditional home-cooked high-fiber, low-fat, low-calorie diet, towards increasing consumption of packaged, ready-to-eat foods which are calorie-dense and contain refined carbohydrates, high fat, salt and sugar; and less fiber. Although fats and oils have been an integral part of our diets, there is a change in the pattern of consumption, in terms of both quality and quantity. A literature search was conducted using the terms "fats, oil consumption in India, effects of vegetable oils, obesity and T2DM in Indians" in the medical search database PubMed (National Library of Medicine, Bethesda, MD, USA) from 1966 to June 2016. A manual search of the relevant quoted references was also carried out from the retrieved articles. Data have also been taken from nutritional surveys in India and worldwide, websites and published documents of the World Health Organization, the Food and Agricultural Organization, National Sample Survey Organization and websites of industries related to oil production. Increasing use of saturated fat, low intake of n-3 poly unsaturated fatty acids and increase in trans-fatty acids, along with increasing intake of dietary sugars has been noted in India. Most importantly, traditional false beliefs and unawareness about health effects of oils continues to be prevalent. Aggressive public health awareness programs coupled with governmental action and guidelines tailored for Indian population are required, to promote less consumption of fats and oils, use of healthy oils and fats, decreased intake of saturated fats and trans fatty acids, and increase intake of n-3 Poly-unsaturated fatty acids and mono-unsaturated fatty acids. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

The Impact of Western Diet and Nutrients on the Microbiota and Immune Response at Mucosal Interfaces

PubMed Central

Statovci, Donjete; Aguilera, Mònica; MacSharry, John; Melgar, Silvia

2017-01-01

Recent findings point toward diet having a major impact on human health. Diets can either affect the gut microbiota resulting in alterations in the host’s physiological responses or by directly targeting the host response. The microbial community in the mammalian gut is a complex and dynamic system crucial for the development and maturation of both systemic and mucosal immune responses. Therefore, the complex interaction between available nutrients, the microbiota, and the immune system are central regulators in maintaining homeostasis and fighting against invading pathogens at mucosal sites. Westernized diet, defined as high dietary intake of saturated fats and sucrose and low intake of fiber, represent a growing health risk contributing to the increased occurrence of metabolic diseases, e.g., diabetes and obesity in countries adapting a westernized lifestyle. Inflammatory bowel diseases (IBD) and asthma are chronic mucosal inflammatory conditions of unknown etiology with increasing prevalence worldwide. These conditions have a multifactorial etiology including genetic factors, environmental factors, and dysregulated immune responses. Their increased prevalence cannot solely be attributed to genetic considerations implying that other factors such as diet can be a major contributor. Recent reports indicate that the gut microbiota and modifications thereof, due to a consumption of a diet high in saturated fats and low in fibers, can trigger factors regulating the development and/or progression of both conditions. While asthma is a disease of the airways, increasing evidence indicates a link between the gut and airways in disease development. Herein, we provide a comprehensive review on the impact of westernized diet and associated nutrients on immune cell responses and the microbiota and how these can influence the pathology of IBD and asthma. PMID:28804483

Evidence of Dietary Improvement and Preventable Costs of Cardiovascular Disease.

PubMed

Zhang, Donglan; Cogswell, Mary E; Wang, Guijing; Bowman, Barbara A

2017-11-01

We conducted a review to summarize preventable medical costs of cardiovascular disease (CVD) associated with improved diet, as defined by the 2020 Strategic Impact Goal of the American Heart Association. We searched databases of PubMed, Embase, CINAHL and ABI/INFORM to identify population-based studies published from January 1995 to December 2015 on CVD medical costs related to excess intake of salt/sodium or sugar-sweetened beverages, and inadequate intake of fruits and vegetables, fish/fish oils/omega-3 fatty acids, or whole grains/fiber/dietary fiber. Based on the American Heart Association's secondary dietary metrics, we also searched the literature on inadequate intake of nuts and excess intake of processed meat and saturated fat. For each component, we evaluated the CVD cost savings if consumption levels were changed. The cost savings were adjusted into 2013 US dollars. Among 330 studies focusing on diet and economic consequences, 16 studies evaluated CVD costs associated with 1 or more dietary components: salt/sodium (n = 13), fruits and vegetables (n = 1), meat (n = 1), and saturated fat (n = 3). In the United States, reducing individual sodium intake to 2,300 mg/day from the current level could potentially save $1,990.9/person per year for hypertension treatment, based on a simulation study. Increasing consumption of fruits and vegetables from <0.5 cup/day to >1.5 cups/day could save $1,568.0/person per year in treatment costs for CVD, based on a cohort study. Potential CVD cost savings associated with diet improvement are substantial. Interventions for reducing sodium intake and increasing fruit and vegetable consumption could be viable means to alleviate the increasing national medical expenditures. Published by Elsevier Inc.

Dietary intakes differ between renal transplant recipients living in patient hotels versus home.

PubMed

Kahra, Terhi; Jenssen, Trond; Løvik, Astrid

2004-04-01

To compare dietary intake and health-related quality of life approximately 6 to 10 weeks after renal transplantation in patients living at home and at a patient hotel, and how the patients were following a heart-healthy diet according to the current American Heart Association guidelines. Cross-sectional observational study. Outpatient clinic at Rikshospitalet University Hospital, Norway. Forty renal transplant patients, 20 patients (14 men and 6 women) in both groups. There were 4 diabetic patients in each group. Dietary intake was assessed by 4-day dietary records. Health-related quality of life was investigated by the SF-36 questionnaire. The main outcome variables were daily energy intake and intakes of protein, total fat, saturated fat, cholesterol, fiber, and fruit and vegetables. The variables were tested by 2-sample t-tests, and significance was set at.05. There was no statistically significant difference in daily energy intake between the groups (P =.08), but there were significantly higher daily intakes of protein (P =.003), total fat (P =.03), monounsaturated fat (P =.02), cholesterol (P =.04), fiber (P =.02), calcium (P =.03), and fruit and vegetables (P =.03) in the group living at the patient hotel. The mean intake of saturated fat was 14.5% of total energy in the group living at home and 14.6% in the group living at the patient hotel. There were no significant differences in health-related quality of life between the groups. The results suggest that there are differences in dietary intake in renal transplant patients living at home compared with those at a patient hotel. It seems that neither of the groups follows current guidelines for reducing the risk of cardiovascular disease.

Race and Region Are Associated with Nutrient Intakes among Black and White Men in the United States12

PubMed Central

Newby, P. K.; Noel, Sabrina E.; Grant, Rachael; Judd, Suzanne; Shikany, James M.; Ard, Jamy

2011-01-01

Stroke mortality rates and prevalence of several chronic diseases are higher in Southern populations and blacks in the US. This study examined the relationships of race (black, white) and region (Stroke Belt, Stroke Buckle, other) with selected nutrient intakes among black and white American men (n = 9229). The Block 98 FFQ assessed dietary intakes and multivariable linear regression analysis was used to examine whether race and region were associated with intakes of fiber, saturated fat, trans fat, sodium, potassium, magnesium, calcium, and cholesterol. Race and region were significant predictors of most nutrient intakes. Black men consumed 1.00% lower energy from saturated fat compared with white men [multivariable-adjusted β: 1.00% (95% CI = −0.88, −1.13)]. A significant interaction between race and region was detected for trans fat (P < 0.0001), where intake was significantly lower among black men compared with white men only in the Stroke Belt [multivariable-adjusted β: −0.21 (95% CI = −0.11, −0.31)]. Among black men, intakes of sodium, potassium, magnesium, and calcium were lower, whereas cholesterol was higher, compared with white men (P < 0.05 for all). Comparing regions, men in the Stroke Buckle had the lowest intakes of fiber, potassium, magnesium, and calcium compared with those in the Stroke Belt and other regions; men in both the Stroke Buckle and Stroke Belt had higher intakes of cholesterol compared with those in other regions (P < 0.005 for all). Given these observed differences in dietary intakes, more research is needed to understand if and how they play a role in the health disparities and chronic disease risks observed among racial groups and regions in the US. PMID:21178088

Auditory-Nerve Responses to Clicks at Low Levels, and the Initial Peak at High Levels, are Suppressed at Opposite Bias-Tone Phases

NASA Astrophysics Data System (ADS)

Nam, Hui; Guinan, John J.

2011-11-01

Apical auditory nerve (AN) fibers show two click-response regions that are both strongly inhibited by medial olivocochlear (MOC) efferents: (1) ringing responses from low- level (LL) clicks that are thought to be enhanced by a "cochlear amplifier," and (2) AN initial peak (ANIPr) responses from moderate-to-high level (˜70-100 dB pSPL) rarefaction clicks. Since MOC fibers synapse and act on outer hair cells (OHCs), the MOC inhibition of these responses indicates that OHC processes are heavily involved in the production of both LL and ANIPr responses. Using AN recordings in anesthetized cats, we explored the role of OHC stereocilia position in the production of these click-response regions by presenting rarefaction clicks at different phases of 50 Hz, 70-110 dB SPL bias tones. Bias effects on LL responses followed the traditional biasing pattern of twice-a-bias-tone-cycle suppression with more suppression at one phase than the other. This suppression is attributable to the bias tone moving the OHC stereocilia toward low-slope, saturation regions of the mechano-electric transduction function with the rest position being closer to one saturation region. A somewhat similar pattern was found for ANIPr responses except that the bias phases of the largest suppressions were different in ANIPr versus LL responses, usually by ˜180 degrees. The data are consistent with the LL and ANIPr responses both being due to active processes in OHCs that are controlled by OHC stereocilia position. The different phases of the LL and ANIPr suppressions indicate that different mechanisms, and perhaps different vibration patterns in the organ of Corti, are involved in the production of LL and ANIPr responses.

Preparation and characterization of Fe3O4-Ag2O quantum dots decorated cellulose nanofibers as a carrier of anticancer drugs for skin cancer.

PubMed

Fakhri, Ali; Tahami, Shiva; Nejad, Pedram Afshar

2017-10-01

The Best performance drug delivery systems designed with Fe 3 O 4 -Ag 2 O quantum dots decorated cellulose nanofibers which that grafted with Etoposide and Methotrexate. Morphology properties were characterized by Scanning and Transmittance electron microscopy. The crystalline structure of prepared sample was evaluated using by X-ray diffraction. The vibrating sample magnetometer analysis was used for magnetic behavior of samples. The size distributions of Fe 3 O 4 -Ag 2 O QDs/Cellulose fibers nanocomposites indicate that the average diameter was 62.5nm. The Saturation magnetization (Ms) indicates the Fe 3 O 4 -Ag 2 O QDs/Cellulose fibers nanocomposites have ferromagnetic properties in nature. For make carrier, the Iron and Silver should be binds to cellulose nanofibers and to drug molecules and observe in UV-vis spectroscopy. The drug release kinetics was studied in vitro as spectrophotometrically. The release of Etoposide and Methotrexate were carried out with a constant speed, and the equilibrium reached at 24 and 30h with a total amount 78.94% and 63.84%, respectively. The results demonstrated that the obtained Fe 3 O 4 -Ag 2 O quantum dots/cellulose fibers nanocomposites could be applied for drug delivery systems. Cytotoxicity and antioxidant study confirmed the activity of the drug incorporated in nanocomposites. In addition, the cytotoxicity of drug was increased when loaded on nanocomposites, compared to pure Fe 3 O 4 -Ag 2 O quantum dots/cellulose fibers nanocomposites. Copyright © 2017 Elsevier B.V. All rights reserved.

A Diet, Physical Activity, and Stress Reduction Intervention in Men with Rising Prostate-Specific Antigen (PSA) after Treatment for Prostate Cancer

PubMed Central

Hébert, James R.; Hurley, Thomas G.; Harmon, Brook E.; Heiney, Sue; Hebert, Christine J.; Steck, Susan E.

2011-01-01

Background Nearly 35% of men treated for prostate cancer (PrCA) will experience biochemically defined recurrence, noted by a rise in PSA, within ten years of definitive therapy. Diet, physical activity, and stress reduction may affect tumor promotion and disease progression. Methods A randomized trial of an intensive diet, physical activity, and meditation intervention was conducted in men with rising post-treatment PSA after definitive treatment for PrCA. Intention-to-treat methods were used to compare usual care to the intervention in 47 men with complete data. Signal detection methods were used to identify dietary factors associated with PSA change. Results The intervention and control groups did not differ statistically on any demographic or disease-related factor. Although the intervention group experienced decreases of 39% in intakes of saturated fatty acid (SFA as percent of total calories) (p<0.0001) and 12% in total energy intake (218 kcal/day p<0.05)], no difference in PSA change was observed by intervention status. Signal detection methods indicated that in men increasing their consumption of fruit, 56% experienced no rise in PSA (vs. 29% in men who did not increase their fruit intake). Among men who increased fruit and fiber intakes, PSA increased in 83% of participants who also increased saturated fatty acid intake (vs. 44% in participants who decreased or maintained saturated fatty acid intake). Conclusion Results are discussed in the context of conventional treatment strategies that were more aggressive when this study was being conducted in the mid-2000s. Positive health changes in a number of lifestyle parameters were observed with the intervention, and both increased fruit and reduced saturated fat intakes were associated with maintaining PSA levels in men with biochemically recurrent disease. PMID:22018935

WE-E-BRE-12: Tumor Microenvironment Dynamics Following Radiation

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

Campos, D; Niles, D; Adamson, E

2014-06-15

Purpose: This work aims to understand the radiation-induced interplay between tumor oxygenation and metabolic activity. These dynamics can potentially serve as biomarkers in assessing treatment response allowing for patient-specific adaptive radiotherapy. Methods: Using patient-derived xenografts of head and neck cancer we assessed tumor oxygenation via fiber-optic probe monitored hemoglobin saturation and Blood Oxygen Level Dependent (BOLD) MRI. Measurements were taken before and after a 10 Gy dose of radiation. Changes in metabolic activity were measured via Fluorescence Lifetime IMaging (FLIM) with the appropriate controls following a 10 Gy dose of radiation. FLIM can non-invasively monitor changes in fluorescence in responsemore » to the microenvironment including being able to detect free and bound states of the intrinsically fluorescent metabolite NADH (Nicotinamide Adenine Dinucleotide). With this information FLIM can accurately quantify the metabolic state of cells that have been radiated. To model the observed changes, a two-compartment, source-sink simulation relating hemoglobin saturation and metabolic activity was performed using MATLAB. Results: Hemoglobin saturation as measured by interstitial probe and BOLD-MRI decreased by 30% within 15 minutes following radiation. FLIM demonstrated a decrease in the mean fluorescence lifetime of NADH by 100 ps following 10 Gy indicating a shift towards glycolytic pathways. Simulation of radiation-induced alterations in tumor oxygenation demonstrated that these changes can be the result of changes in either vasculature or metabolic activity. Conclusion: Radiation induces significant changes in hemoglobin saturation and metabolic activity. These alterations occur on time scales approximately the duration of common radiation treatments. Further understanding these dynamics has important implications with regard to improvement of therapy and biomarkers of treatment response.« less

Selective Sampling with Direct Ion Mobility Spectrometric Detection for Explosives Analysis

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

Harvey, Scott D; Ewing, Robert G; Waltman, Melanie J

2009-06-29

This study investigates the potential and limitations of a streamlined, field-deployable analytical approach that involves selective capture of explosive materials with direct analysis by ion mobility spectrometry (IMS). Selective capture of explosives was performed on deactivated quartz fiber filters impregnated with metal β-diketonate polymers. These Lewis acidic polymers selectively interact with Lewis base analytes such as explosives. The filter coupons could be directly inserted into an IMS instrument for analysis. The uptake kinetics of 2,4,6-trinitrotoluene (TNT) from a saturated atmosphere were characterized, and based on these studies, passive equilibrium sampling was applied to estimate the TNT concentration within an ammunitionmore » magazine that contained bulk TNT. Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) uptake from a saturated environment also was examined over a one-month period. Each incremental sampling period showed increasing quantities of RDX culminating with collection of approximately 5 ng of RDX on the coupon at the end of one month. This is the first time that gas-phase uptake of RDX has been demonstrated.« less

Enhanced enzymatic hydrolysis of lignocellulose by optimizing enzyme complexes.

PubMed

Zhang, Mingjia; Su, Rongxin; Qi, Wei; He, Zhimin

2010-03-01

To enhance the conversion of the cellulose and hemicellulose, the corncob pretreated by aqueous ammonia soaking was hydrolyzed by enzyme complexes. The saturation limit for cellulase (Spezyme CP) was determined as 15 mg protein/g glucan (50 filter paper unit (FPU)/g glucan). The accessory enzymes (beta-glucosidase, xylanase, and pectinase) were supplemented to hydrolyze cellobiose (cellulase-inhibiting product), hemicellulose, and pectin (the component covering the fiber surfaces), respectively. It was found that beta-glucosidase (Novozyme 188) loading of 1.45 mg protein/g glucan [30 cellobiase units (CBU)/g glucan] was enough to eliminate the cellobiose inhibitor, and 2.9 mg protein/g glucan (60 CBU/g glucan) was the saturation limit. The supplementation of xylanase and pectinase can increase the conversion of cellulose and hemicellulose significantly. The yields of glucose and xylose enhanced with the increasing enzyme loading, but the increasing trend became low at high loading. Compared with xylanase, pectinase was more effective to promote the hydrolysis of cellulose and hemicellulose. The supplementation of pectinase with 0.12 mg protein/g glucan could increase the yields of glucose and xylose by 7.5% and 29.3%, respectively.

Septal cholinergic neuromodulation tunes the astrocyte-dependent gating of hippocampal NMDA receptors to wakefulness

PubMed Central

Papouin, Thomas; Dunphy, Jaclyn; Tolman, Michaela; Dineley, Kelly T.; Haydon, Philip G.

2017-01-01

Summary The activation of the N-methyl D-aspartate receptor (NMDAR) is controlled by a glutamate-binding site and a distinct, independently regulated, co-agonist-binding site. In most brain regions, the NMDAR co-agonist is the astrocyte-derived gliotransmitter D-serine. We found that D-serine levels oscillate in mouse hippocampus as a function of wakefulness, in vitro and in vivo. This causes a full saturation of the NMDAR co-agonist site in the dark (active)-phase that dissipates to sub-saturating levels during the light (sleep)-phase, and influences learning performance throughout the day. We demonstrate that hippocampal astrocytes sense the wakefulness-dependent activity of septal cholinergic fibers through the α7-nicotinic acetylcholine receptor (α7nAChR), whose activation drives D-serine release. We conclude that astrocytes tune the gating of synaptic NMDARs to the vigilance state and demonstrate that this is directly relevant to schizophrenia, a disorder characterized by NMDAR and cholinergic hypofunctions. Indeed, bypassing cholinergic activity with a clinically-tested α7nAChR agonist successfully enhances NMDARs activation. PMID:28479102

DNB heat flux in forced convection of liquid hydrogen for a wire set in central axis of vertically mounted flow channel

NASA Astrophysics Data System (ADS)

Matsumoto, T.; Shirai, Y.; Shiotsu, M.; Fujita, K.; Kainuma, T.; Tatsumoto, H.; Naruo, Y.; Kobayashi, H.; Nonaka, S.; Inatani, Y.

2017-12-01

Liquid hydrogen has excellent physical properties, high latent heat and low viscosity of liquid, as a coolant for superconductors like MgB2. The knowledge of Departure from Nucleate Boiling (DNB) heat flux of liquid hydrogen is necessary for designing and cooling analysis of high critical temperature superconducting devices. In this paper, DNB heat fluxes of liquid hydrogen were measured under saturated and subcooled conditions at absolute pressures of 400, 700 and 1100 kPa for various flow velocities. Two wire test heaters made by Pt-Co alloy with the length of 200 mm and the diameter of 0.7 mm were used. And these round heaters were set in central axis of a flow channel made of Fiber Reinforced Plastic (FRP) with inner diameters of 8 mm and 12 mm. These test bodies were vertically mounted and liquid hydrogen flowed upward through the channel. From these experimental values, the correlations of DNB heat flux under saturated and subcooled conditions are presented in this paper.

Quantitative detection of the colloidal gold immunochromatographic strip in HSV color space

NASA Astrophysics Data System (ADS)

Wu, Yuanshu; Gao, Yueming; Du, Min

2014-09-01

In this paper, a fast, reliable and accurate quantitative detection method for the colloidal gold immunochromatographic strip(GICA) is presented. An image acquisition device which is mainly composed of annular LED source, zoom ratio lens, and 10bit CMOS image sensors with 54.5dB SNR is designed for the detection. Firstly, the test line is extracted from the strip window through using the H component peak points of the HSV space as the clustering centers via the Fuzzy C-Means(FCM) clustering method. Then, a two dimensional eigenvalue composed with the hue(H) and saturation(S) of HSV space was proposed to improve the accuracy of the quantitative detection. At last, the experiment of human chorionic gonadotropin(HCG) with the concentration range 0-500mIU/mL is carried out. The results show that the linear correlation coefficient between this method and optical density(OD) values measured by the fiber optical sensor reach 96.74%. Meanwhile, the linearity of fitting curve constructed with concentration was greater than 95.00%.

Mineral oil barrier sequential polymer treatment for recycled paper products in food packaging

NASA Astrophysics Data System (ADS)

Paul, Uttam C.; Fragouli, Despina; Bayer, Ilker S.; Mele, Elisa; Conchione, Chiara; Cingolani, Roberto; Moret, Sabrina; Athanassiou, Athanassia

2017-01-01

Recycled cellulosic paperboards may include mineral oils after the recycle process, which together with their poor water resistance limit their use as food packaging materials. In this work, we demonstrate that a proper functionalization of the recycled paper with two successive polymer treatments, imposes a mineral oil migration barrier and simultaneously renders it waterproof and grease resistant, making it an ideal material for food contact. The first poly (methyl methacrylate) treatment penetrates the paper network and creates a protective layer around every fiber, permitting thus the transformation of the paperboard to a hydrophobic material throughout its thickness, reducing at the same time the mineral oil migration. Subsequently, the second layer with a cyclic olefin copolymer fills the open pores of the surface, and reduces the mineral oil hydrocarbons migration at levels below those proposed by the BMEL. Online liquid chromatography-gas chromatography coupled with flame ionization detection quantitatively demonstrate that this dual functional treatment prevents the migration of both saturated (mineral oil saturated hydrocarbons) and aromatic hydrocarbon (mineral oil aromatic hydrocarbons) mineral oils from the recycled paperboard to a dry food simulant.

Characterization of the Performance of Sapphire Optical Fiber in Intense Radiation Fields, when Subjected to Very High Temperatures

NASA Astrophysics Data System (ADS)

Petrie, Christian M.

The U.S. Department of Energy is interested in extending optically-based instrumentation from non-extreme environments to extremely high temperature radiation environments for the purposes of developing in-pile instrumentation. The development of in-pile instrumentation would help support the ultimate goal of understanding the behavior and predicting the performance of nuclear fuel systems at a microstructural level. Single crystal sapphire optical fibers are a promising candidate for in-pile instrumentation due to the high melting temperature and radiation hardness of sapphire. In order to extend sapphire fiber-based optical instrumentation to high temperature radiation environments, the ability of sapphire fibers to adequately transmit light in such an environment must first be demonstrated. Broadband optical transmission measurements of sapphire optical fibers were made in-situ as the sapphire fibers were heated and/or irradiated. The damage processes in sapphire fibers were also modeled from the primary knock-on event from energetic neutrons to the resulting damage cascade in order to predict the formation of stable defects that ultimately determine the resulting change in optical properties. Sapphire optical fibers were shown to withstand temperatures as high as 1300 °C with minimal increases in optical attenuation. A broad absorption band was observed to grow over time without reaching a dynamic equilibrium when the sapphire fiber was heated at temperatures of 1400 °C and above. The growth of this absorption band limits the use of sapphire optical fibers, at least in air, to temperatures of 1300 °C and below. Irradiation of sapphire fibers with gamma rays caused saturation of a defect center located below 500 nm, and extending as far as ~1000 nm, with little effect on the transmission at 1300 and 1550 nm. Increasing temperature during gamma irradiation generally reduced the added attenuation. Reactor irradiation of sapphire fibers caused an initial rapid increase in attenuation, followed by a linear increase with continued irradiation time at constant reactor power. The linear increases were a result of displacement damage, and the rate of increase was proportional to the neutron flux. The transmission of sapphire fibers at 1300 and 1550 nm in a reactor radiation environment would ultimately be limited by the growth of low wavelength defect centers, whose tails extend into the near infrared. A model was proposed for the reactor radiation-induced attenuation that involves three previously reported color centers. The model accounts for gamma radiation-induced ionization of pre-existing defects, generation of new defects via displacement damage, and conversion between defect centers via ionization and charge recombination. Heated reactor irradiation experiments showed that the rate of increase of the added attenuation during constant power reactor irradiation monotonically decreases with increasing temperature up to 1000 °C, with the most significant decrease occurring between 300 and 600 °C. Testing of sapphire fiber-based sensors under irradiation at high temperatures is recommended as future work, along with advanced life irradiation testing, for example in the Advanced Test Reactor or the High Flux Isotope Reactor.

Double-Wall Carbon Nanotubes for Wide-Band, Ultrafast Pulse Generation

PubMed Central

2014-01-01

We demonstrate wide-band ultrafast optical pulse generation at 1, 1.5, and 2 μm using a single-polymer composite saturable absorber based on double-wall carbon nanotubes (DWNTs). The freestanding optical quality polymer composite is prepared from nanotubes dispersed in water with poly(vinyl alcohol) as the host matrix. The composite is then integrated into ytterbium-, erbium-, and thulium-doped fiber laser cavities. Using this single DWNT–polymer composite, we achieve 4.85 ps, 532 fs, and 1.6 ps mode-locked pulses at 1066, 1559, and 1883 nm, respectively, highlighting the potential of DWNTs for wide-band ultrafast photonics. PMID:24735347

Multi-Watt femtosecond optical parametric master oscillator power amplifier at 43 MHz.

PubMed

Mörz, Florian; Steinle, Tobias; Steinmann, Andy; Giessen, Harald

2015-09-07

We present a high repetition rate mid-infrared optical parametric master oscillator power amplifier (MOPA) scheme, which is tunable from 1370 to 4120nm. Up to 4.3W average output power are generated at 1370nm, corresponding to a photon conversion efficiency of 78%. Bandwidths of 6 to 12nm with pulse durations between 250 and 400fs have been measured. Strong conversion saturation over the whole signal range is observed, resulting in excellent power stability. The system consists of a fiber-feedback optical parametric oscillator that seeds an optical parametric power amplifier. Both systems are pumped by the same Yb:KGW femtosecond oscillator.

A 12.1-W SESAM mode-locked Yb:YAG thin disk laser

NASA Astrophysics Data System (ADS)

Yingnan, Peng; Zhaohua, Wang; Dehua, Li; Jiangfeng, Zhu; Zhiyi, Wei

2016-05-01

Pumped by a 940 nm fiber-coupled diode laser, a passively mode-locked Yb:YAG thin disk oscillator was demonstrated with a semiconductor saturable absorber mirror (SESAM). 12.1 W mode-locked pulses were obtained with pulse duration of 698 fs at the repetition rate of 57.43 MHz. Measurement showed that the beam quality was close to the diffraction limit. Project supported by the National Key Basic Research Program of China (Grant No. 2013CB922402), the National Major Instrument Program of China (Grant No. 2012YQ120047), and the National Natural Science Foundation of China (Grant No. 61210017).

Utilization of modernized global navigation satellite systems for aircraft-based navigation integrity

NASA Astrophysics Data System (ADS)

Ene, Alexandru

The objective of this dissertation is to assess whether or not two particular biocomposite materials, made from hemp fabric and cellulose acetate or polyhydroxybutyrate matrices, are capable of being used for structural and/or construction purposes within in the construction and building industry. The objective of this dissertation was addressed by conducting research to meet the following three goals: (1) to measure the basic mechanical properties of hemp/cellulose acetate and hemp/PHB biocomposites and evaluate if they suitable for use in construction applications, (2) to determine how quickly moisture diffuses into the biocomposite materials and how the moisture affects the mechanical behavior, and (3) to determine how well simple models can predict behavior of structural scale laminates in tension and flexure using biocomposite ply behavior. Compression molding was used to manufacturing the biocomposites from hemp fabric and the themoplastic matrices: cellulose acetate and polyhydroxybutyrate. Four methods for determining the fiber volume fraction were evaluated, and the dissolution method, using different solvents for each matrix type, was used to determine the fiber volume fraction for each composite plate manufactured. Both types of biocomposite were tested in tension, compression, shear, and flexure and the measured properties were compared to wood and engineered wood products to assess whether the biocomposite properties are suitable for use in the construction industry. The biocomposites were conditioned in a humid environment to determine the rate of moisture diffusion into the materials. Then saturated specimens and specimens that were saturated and then dried were tested in tension to evaluate how moisture absorption affects the mechanical behavior of the biocomposites. Finally, simple models of laminate behavior based on laminate plate theory were evaluated to determine if ply level behavior could be used to predict structural scale laminate behavior. While the biocomposite strengths in flexure, compression, and shear were comparable to the strengths of wood and wood-based products parallel to grain, the biocomposite strengths exceeded the strengths perpendicular to the wood grain, as would be expected with fabric reinforcement. The biocomposite moduli of elasticity were between 35% and 75% of the wood moduli parallel to grain. While structural shape of the biocomposites could be manipulated to achieve a comparable structural stiffness to replace wood and short fiber FRPs, the biocomposites have comparable stiffness to the engineered wood-products. Thus, in terms of mechanical properties, the biocomposites can be used in place of engineered-wood products. Yet, the higher densities of the biocomposites as compared to wood and engineered-wood products may limit their implementation in construction. The diffusion coefficients for both biocomposites were comparable to wood and higher than the coefficients for synthetic composites as expected due to the hydrophilicity of the natural fibers. Significantly greater moisture absorption of the hemp/cellulose acetate composite as compared to the hemp/PHB composite was attributed to the cellulose acetate itself being hydrophilic whereas PHB is hydrophobic. The rate of diffusion for both materials was found to increase with increasing temperature. Moisture absorption negatively affected the biocomposites as shown through lower initial stiffnesses and higher strains at failure of saturated specimens. The hemp/cellulose acetate composites were much more affected by moisture absorption than the hemp/PHB composites likely because the moisture plasticized the cellulose acetate and also weakened the interfacial fiber-matrix bond. Moisture was assumed to cause permanent damage because the stress-strain behavior did not return to the unconditioned behavior upon drying of the saturated specimens. The degradation of mechanical properties upon introduction to humid environments limits the potential applications of these biocomposites. For these biocomposites to be used widely within the construction industry, they must therefore be protected from moisture for example through sealants and/or fiber treatments. Classical laminate plate theory was shown to be effective in predicting the initial linear behavior of all of the laminates in tension and flexure, but did not capture stiffness degradation or the full nonlinear stress-strain response of the biocomposites because the model was for linear elastic materials. Use of this model would be appropriate for design of deflection-limited applications within certain stress ranges. The modified nonlinear laminate plate theory predicted the initial stress-strain response well, but at higher strains overestimated the strength and stiffness. The overestimation was attributed to the constitutive model assuming uncoupled stress-strain behavior for each strain component and, additionally in flexure, to the use of tensile behavior as the constitutive behavior in compression. While the simple models provided an adequate prediction of laminate behavior at low strains, to predict behavior at higher strains, it is recommended instead to evaluate the use of finite element analysis to predict response using experimental stress-strain as models for orthotropic materials and non-linear behavior are well-established. (Abstract shortened by UMI.)

Mechanical characterization and structural assessment of biocomposites for construction

NASA Astrophysics Data System (ADS)

Christian, Sarah Jane

The objective of this dissertation is to assess whether or not two particular biocomposite materials, made from hemp fabric and cellulose acetate or polyhydroxybutyrate matrices, are capable of being used for structural and/or construction purposes within in the construction and building industry. The objective of this dissertation was addressed by conducting research to meet the following three goals: (1) to measure the basic mechanical properties of hemp/cellulose acetate and hemp/PHB biocomposites and evaluate if they suitable for use in construction applications, (2) to determine how quickly moisture diffuses into the biocomposite materials and how the moisture affects the mechanical behavior, and (3) to determine how well simple models can predict behavior of structural scale laminates in tension and flexure using biocomposite ply behavior. Compression molding was used to manufacturing the biocomposites from hemp fabric and the themoplastic matrices: cellulose acetate and polyhydroxybutyrate. Four methods for determining the fiber volume fraction were evaluated, and the dissolution method, using different solvents for each matrix type, was used to determine the fiber volume fraction for each composite plate manufactured. Both types of biocomposite were tested in tension, compression, shear, and flexure and the measured properties were compared to wood and engineered wood products to assess whether the biocomposite properties are suitable for use in the construction industry. The biocomposites were conditioned in a humid environment to determine the rate of moisture diffusion into the materials. Then saturated specimens and specimens that were saturated and then dried were tested in tension to evaluate how moisture absorption affects the mechanical behavior of the biocomposites. Finally, simple models of laminate behavior based on laminate plate theory were evaluated to determine if ply level behavior could be used to predict structural scale laminate behavior. While the biocomposite strengths in flexure, compression, and shear were comparable to the strengths of wood and wood-based products parallel to grain, the biocomposite strengths exceeded the strengths perpendicular to the wood grain, as would be expected with fabric reinforcement. The biocomposite moduli of elasticity were between 35% and 75% of the wood moduli parallel to grain. While structural shape of the biocomposites could be manipulated to achieve a comparable structural stiffness to replace wood and short fiber FRPs, the biocomposites have comparable stiffness to the engineered wood-products. Thus, in terms of mechanical properties, the biocomposites can be used in place of engineered-wood products. Yet, the higher densities of the biocomposites as compared to wood and engineered-wood products may limit their implementation in construction. The diffusion coefficients for both biocomposites were comparable to wood and higher than the coefficients for synthetic composites as expected due to the hydrophilicity of the natural fibers. Significantly greater moisture absorption of the hemp/cellulose acetate composite as compared to the hemp/PHB composite was attributed to the cellulose acetate itself being hydrophilic whereas PHB is hydrophobic. The rate of diffusion for both materials was found to increase with increasing temperature. Moisture absorption negatively affected the biocomposites as shown through lower initial stiffnesses and higher strains at failure of saturated specimens. The hemp/cellulose acetate composites were much more affected by moisture absorption than the hemp/PHB composites likely because the moisture plasticized the cellulose acetate and also weakened the interfacial fiber-matrix bond. Moisture was assumed to cause permanent damage because the stress-strain behavior did not return to the unconditioned behavior upon drying of the saturated specimens. The degradation of mechanical properties upon introduction to humid environments limits the potential applications of these biocomposites. For these biocomposites to be used widely within the construction industry, they must therefore be protected from moisture for example through sealants and/or fiber treatments. Classical laminate plate theory was shown to be effective in predicting the initial linear behavior of all of the laminates in tension and flexure, but did not capture stiffness degradation or the full nonlinear stress-strain response of the biocomposites because the model was for linear elastic materials. Use of this model would be appropriate for design of deflection-limited applications within certain stress ranges. The modified nonlinear laminate plate theory predicted the initial stress-strain response well, but at higher strains overestimated the strength and stiffness. The overestimation was attributed to the constitutive model assuming uncoupled stress-strain behavior for each strain component and, additionally in flexure, to the use of tensile behavior as the constitutive behavior in compression. While the simple models provided an adequate prediction of laminate behavior at low strains, to predict behavior at higher strains, it is recommended instead to evaluate the use of finite element analysis to predict response using experimental stress-strain as models for orthotropic materials and non-linear behavior are well-established. (Abstract shortened by UMI.)

Reduction of GABA/sub B/ receptor binding induced by climbing fiber degeneration in the rat cerebellum

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

Kato, K.; Fukuda, H.

1985-07-22

When the rat cerebellar climbing fibers degenerated, as induced by lesioning the inferior olive with 3-acetylpyridine (3-AP), GABA/sub B/ receptor binding determined with /sup 3/H-(+/-)baclofen was reduced in the cerebellum but not in the cerebral cortex of rats. Computer analysis of saturation data revealed two components of the binding sites, and indicated that decrease of the binding in the cerebellum was due to reduction in receptor density, mainly of the high-affinity sites, the B/sub max/ of which was reduced to one-third that in the control animals. In vitro treatment with 3-AP, of the membranes prepared from either the cerebellum ormore » the cerebral cortex, induced no alteration in the binding sites, thereby indicating that the alteration of GABA/sub B/ sites induced by in vivo treatment with 3-AP is not due to a direct action of 3-AP on the receptor. GABA/sub A/ and benzodiazepine receptor binding labelled with /sup 3/H-muscimol and /sup 3/H-diazepam, respectively, in both of brain regions was not affected by destruction of the inferior olive. These results provide evidence that some of the GABA/sub B/ sites but neither GABA/sub A/ nor benzodiazepine receptors in the cerebellum are located at the climbing fiber terminals. 28 references, 4 figures, 2 tables.« less

Investigation on the impact of irregular fringe patterns of a single-fiber Mach-Zehnder interferometer on its sensing capabilities

NASA Astrophysics Data System (ADS)

Kumar, Naveen; Kumar, Ashish

2018-07-01

A novel single-mode single-fiber (SMSF) MZI formed by cascading of two non-adiabatic fiber tapers, with stable and repeatable spectrum, has been found to be useful in sensing applications in recent times. A multimode interference based novel simulation approach is proposed to predict the sensing characteristics of SMSF-MZI and is validated with experimental observation. The proposed method includes solving of simultaneous non-homogenous equations for determining the amplitudes of the interfering modes excited in the tapered section of the interferometer. The simulated fringe pattern and the experimental spectral response converge to some important comprehension reported for the first time. A linear shift in output spectral response, of SMSF-MZI, due to change in optical path length induced by temperature/strain etc., is likely to be characterized by three modes interference occurring in the interference region of the interferometer. Whereas if the spectral shift starts saturating at moderately higher temperature/strain, then the formation of interference fringes are possibly governed by two modes interference. Further, it was also explained that a SMSF-MZI with variable fringe widths in its spectral pattern exhibits higher sensitivity than that of the SMSF-MZI having wavelength spectrum with uniform free spectral range. These findings are useful in selecting and predicting the sensitivity of a given SMSF-MZI, based on its spectrum, for sensing applications.

Effects of a diet high in plant sterols, vegetable proteins, and viscous fibers (dietary portfolio) on circulating sterol levels and red cell fragility in hypercholesterolemic subjects.

PubMed

Jones, Peter J; Raeini-Sarjaz, Mahmoud; Jenkins, David J A; Kendall, Cyril W C; Vidgen, Edward; Trautwein, Elke A; Lapsley, Karen G; Marchie, Augustine; Cunnane, Stephen C; Connelly, Philip W

2005-02-01

Plant sterols, soy proteins, viscous fibers, and nuts are advised for cholesterol reduction, but their combined effect on plant sterol absorption has never been tested. We assessed their combined action on serum sterols in hyperlipidemic subjects who were following low-saturated fat diets before starting the study and who returned to these diets post-test. The 1-mon test (combination) diet was high in plant sterols (1 g/1,000 kcal), soy protein (23 g/1,000 kcal), viscous fiber (9 g/1,000 kcal), and almonds (14 g/1000 kcal). Fasting blood was obtained for serum lipids and sterols, and erythrocytes were obtained for fragility prior to and at 2-wk intervals during the study. The combination diet raised serum campesterol concentrations by 50% and beta-sitosterol by 27%, although these changes were not significant after Bonferroni correction; near-maximal rises were found by the end of the first week, but no change was found in red cell fragility despite a 29% reduction in the LDL cholesterol level. No significant associations were observed between changes in red cell fragility and blood lipids or sterols. We conclude that plant sterols had a minimal impact on serum sterol concentrations or red cell fragility in hyperlipidemic subjects on diets that greatly reduced their serum lipids.

A Biohybrid Artificial Lung Prototype With Active Mixing of Endothelialized Microporous Hollow Fibers

PubMed Central

Polk, Alexa A.; Maul, Timothy M.; McKeel, Daniel T.; Snyder, Trevor A.; Lehocky, Craig A.; Pitt, Bruce; Stolz, Donna Beer; Federspiel, William J.; Wagner, William R.

2014-01-01

Acute respiratory distress syndrome (ARDS) affects nearly 150,000 patients per year in the US, and is associated with high mortality (≈40%) and suboptimal options for patient care. Mechanical ventilation and extracorporeal membrane oxygenation are limited to short-term use due to ventilator-induced lung injury and poor bio-compatibility, respectively. In this report, we describe the development of a biohybrid lung prototype, employing a rotating endothelialized microporous hollow fiber (MHF) bundle to improve blood biocompatibility while MHF mixing could contribute to gas transfer efficiency. MHFs were surface modified with radio frequency glow discharge (RFGD) and protein adsorption to promote endothelial cell (EC) attachment and growth. The MHF bundles were placed in the biohybrid lung prototype and rotated up to 1,500 revolutions per minute (rpm) using speed ramping protocols to condition ECs to remain adherent on the fibers. Oxygen transfer, thrombotic deposition, and EC p-selectin expression were evaluated as indicators of biohybrid lung functionality and biocompatibility. A fixed aliquot of blood in contact with MHF bundles rotated at either 250 or 750 rpm reached saturating pO2 levels more quickly with increased rpm, supporting the concept that fiber rotation would positively contribute to oxygen transfer. The presence of ECs had no effect on the rate of oxygen transfer at lower fiber rpm, but did provide some resistance with increased rpm when the overall rate of mass transfer was higher due to active mixing. RFGD followed by fibronectin adsorption on MHFs facilitated near confluent EC coverage with minimal p-selectin expression under both normoxic and hyperoxic conditions. Indeed, even subconfluent EC coverage on MHFs significantly reduced thrombotic deposition adding further support that endothelialization enhances, blood biocompatibility. Overall these findings demonstrate a proof-of-concept that a rotating endothelialized MHF bundle enhances gas transfer and biocompatibility, potentially producing safer, more efficient artificial lungs. PMID:20091735

Effect of water absorption on the mechanical properties of poly(3-hydroxybutyrate)/vegetable fiber composites

NASA Astrophysics Data System (ADS)

Marinho, Vithória A. D.; Carvalho, Laura H.; Canedo, Eduardo L.

2015-05-01

The present work studies the effect of water absorption on the performance of composites of poly(3-hydroxybutyrate) (PHB) - a fully biodegradable semi-crystalline thermoplastic obtained from renewable resources through low-impact biotechnological process, biocompatible and non-toxic - and vegetable fiber from the fruit (coconut) of babassu palm tree.Water resistance is an important characteristic of structural composites, that may exposed to rain and humid environments. Both water absorption capacity (water solubility in the material) and the rate of water absorption (controlled by the diffusivity of water in the material) are important parameters. However, water absorption per se may not be the most important characteristic, insofar as the performance and applications of the compounds. It is the effect of the water content on the ultimate properties that determine the suitability of the material for applications that involve prolonged exposure to water.PHB/babassu composites with 0-20% load were prepared in an internal mixer. Two different types of babassu fibers having two different article size ranges were compounded with PHB and test specimens molded by compression. The water absorption capacity and the kinetic constant of water absorption were measured in triplicate. Mechanical properties under tension were measured for dry and moist specimens with different amounts of absorbed water.Results indicate that the performance of the composites is comparable to that of the pure matrix. Water absorption capacity increases from 0.7% (pure PHB) to 4% (PHB/20% babassu), but the water diffusivity (4.10□8 cm2/s) was found to be virtually independent of the water absorption level. Water absorption results in moderate drop in elastic modulus (10-30% at saturation, according to fiber content) but has little effect on tensile strength and elongation at break. Fiber type and initial particle size do not have a significant effect on water absorption or mechanical properties.

Vector solitons with polarization instability and locked polarization in a fiber laser

NASA Astrophysics Data System (ADS)

Tang, Dingkang; Zhang, Jian-Guo; Liu, Yuanshan

2012-07-01

We investigate the characteristics of vector solitons with and without locked phase velocities of orthogonal polarization components in a specially-designed laser cavity which is formed by a bidirectional fiber loop together with a semiconductor saturable absorber mirror. The characteristics of the two states are compared in the temporal and spectrum domain, respectively. Both of the two states exhibit the characteristic of mode locking while the two orthogonal polarization components are not resolved. However, for the vector soliton with unlocked phase velocities, identical intensity varies after passing through a polarization beam splitter (PBS) outside the laser cavity. Contrary to the polarization rotation locked vector soliton, the intensity does not change periodically. For the polarization-locked vector soliton (PLVS), the identical pulse intensity is still obtained after passing through the PBS and can be observed on the oscilloscope screen after photodetection. A coupler instead of a circulator is integrated in the laser cavity and strong interaction on the polarization resolved spectra of the PLVS is observed. By comparing the two states, we conclude that interaction between the two orthogonal components contributes to the locked phase velocities.

Polycystic ovary syndrome (PCOS) and other androgen excess-related conditions: can changes in dietary intake make a difference?

PubMed

Liepa, George U; Sengupta, Aditi; Karsies, Danielle

2008-02-01

Polycystic ovary syndrome (PCOS) is a condition that involves the excess production of androgens. It affects up to 10% of all American women and can lead to the development of acne, hirsutism, and infertility. It has also been associated with coronary heart disease, diabetes, and metabolic syndrome. Over half of the women who are diagnosed with PCOS are overweight or obese. Recommendations are made for overweight/obese women to lose weight via diet and exercise. Women with PCOS should also consider maintaining a diet that is patterned after the type 2 diabetes diet. This diet includes an increase in fiber and a decrease in refined carbohydrates, as well as a decrease in trans and saturated fats and an increase in omega-3 and omega-9 fatty acids. Foods that contain anti-inflammatory compounds (fiber, omega-3 fatty acids, vitamin E, and red wine) should also be emphasized. Evidence is provided for the impact of these dietary changes on improvements in the androgen profile of PCOS patients.

AFEII Analog Front End Board Design Specifications

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

Rubinov, Paul; /Fermilab

2005-04-01

This document describes the design of the 2nd iteration of the Analog Front End Board (AFEII), which has the function of receiving charge signals from the Central Fiber Tracker (CFT) and providing digital hit pattern and charge amplitude information from those charge signals. This second iteration is intended to address limitations of the current AFE (referred to as AFEI in this document). These limitations become increasingly deleterious to the performance of the Central Fiber Tracker as instantaneous luminosity increases. The limitations are inherent in the design of the key front end chips on the AFEI board (the SVXIIe and themore » SIFT) and the architecture of the board itself. The key limitations of the AFEI are: (1) SVX saturation; (2) Discriminator to analog readout cross talk; (3) Tick to tick pedestal variation; and (4) Channel to channel pedestal variation. The new version of the AFE board, AFEII, addresses these limitations by use of a new chip, the TriP-t and by architectural changes, while retaining the well understood and desirable features of the AFEI board.« less

Unidirectional, dual-comb lasing under multiple pulse formation mechanisms in a passively mode-locked fiber ring laser

NASA Astrophysics Data System (ADS)

Liu, Ya; Zhao, Xin; Hu, Guoqing; Li, Cui; Zhao, Bofeng; Zheng, Zheng

2016-09-01

Dual-comb lasers from which asynchronous ultrashort pulses can be simultaneously generated have recently become an interesting research subject. They could be an intriguing alternative to the current dual-laser optical-frequency-comb source with highly sophisticated electronic control systems. If generated through a common light path traveled by all pulses, the common-mode noises between the spectral lines of different pulse trains could be significantly reduced. Therefore, coherent dual-comb generation from a completely common-path, unidirectional lasing cavity would be an interesting territory to explore. In this paper, we demonstrate such a dual-comb lasing scheme based on a nanomaterial saturable absorber with additional pulse narrowing and broadening mechanisms concurrently introduced into a mode-locked fiber laser. The interactions between multiple soliton formation mechanisms result in unusual bifurcation into two-pulse states with quite different characteristics. Simultaneous oscillation of pulses with four-fold difference in pulsewidths and tens of Hz repetition rate difference is observed. The coherence between these spectral-overlapped, picosecond and femtosecond pulses is further verified by the corresponding asynchronous cross-sampling and dual-comb spectroscopy measurements.

Fat, Sugar, Whole Grains and Heart Disease: 50 Years of Confusion.

PubMed

Temple, Norman J

2018-01-04

During the 1970s some investigators proposed that refined carbohydrates, especially sugar and a low intake of dietary fiber, were major factors in coronary heart disease (CHD). This suggestion was eclipsed by the belief that an excess intake of saturated fatty acids (SFA) was the key dietary factor, a view that prevailed from roughly 1974 to 2014. Findings that have accumulated since 1990 inform us that the role of SFA in the causation of CHD has been much exaggerated. A switch from SFA to refined carbohydrates does not lower the ratio of total cholesterol to HDL-cholesterol in the blood and therefore does not prevent CHD. A reduced intake of SFA combined with an increased intake of polyunsaturated fatty acids lowers the ratio of total cholesterol to HDL-cholesterol; this may reduce the risk of CHD. The evidence linking carbohydrate-rich foods with CHD has been steadily strengthening. Refined carbohydrates, especially sugar-sweetened beverages, increase the risk of CHD. Conversely, whole grains and cereal fiber are protective. An extra one or 2 servings per day of these foods increases or decreases risk by approximately 10% to 20%.

Building on Sub-Arctic Soil: Geopolymerization of Muskeg to a Densified Load-Bearing Composite.

PubMed

Waetzig, Gregory R; Cho, Junsang; Lacroix, Max; Banerjee, Sarbajit

2017-11-07

The marshy water-saturated soil typical of the sub-Arctic represents a considerable impediment to the construction of roads, thereby greatly hindering human habitation and geological excavation. Muskeg, the native water-laden topsoil characteristic of the North American sub-Arctic, represents a particularly vexing challenge for road construction. Muskeg must either be entirely excavated, or for direct construction on muskeg, a mix of partial excavation and gradual compaction with the strategic placement of filling materials must be performed. Here, we demonstrate a novel and entirely reversible geopolymerization method for reinforcing muskeg with wood fibers derived from native vegetation with the addition of inorganic silicate precursors and without the addition of extraneous metal precursors. A continuous siloxane network is formed that links together the muskeg, wood fibers, and added silicates yielding a load-bearing and low-subsidence composite. The geopolymerization approach developed here, based on catalyzed formation of a siloxane network with further incorporation of cellulose, allows for an increase of density as well as compressive strength while reducing the compressibility of the composite.

Study of the influence of the agarose hydrogel layer thickness on sensitivity of the coated silica microsphere resonator to humidity.

PubMed

Mallik, Arun Kumar; Farrell, Gerald; Wu, Qiang; Semenova, Yuliya

2017-05-10

In this paper, we investigate both theoretically and experimentally the influence of the agarose hydrogel layer thickness on the sensitivity of a proposed relative humidity (RH) sensor based on a silica microsphere resonator coated with agarose hydrogel. The operating principle of the sensor relies on excitation of whispering gallery modes (WGMs) in the coated silica microsphere using the evanescent field of a tapered fiber. A change in the ambient relative humidity is detected by measuring the wavelength shift of the WGMs in the transmission spectrum of the tapered fiber. Using perturbation theory, we analyze the influence of the agarose coating thickness on the sensitivity of the proposed sensor and compare the results of this analysis with experimental findings for different coating layer thicknesses. We demonstrate that an increase in the coating layer thickness initially leads to an increase in the sensitivity to RH and reaches saturation at higher values of the agarose layer thickness. The results of the study are useful for the design and optimization of microsphere sensor parameters to meet a performance specification.

Application of Glass Fiber Waste Polypropylene Aggregate in Lightweight Concrete – thermal properties

NASA Astrophysics Data System (ADS)

Citek, D.; Rehacek, S.; Pavlik, Z.; Kolisko, J.; Dobias, D.; Pavlikova, M.

2018-03-01

Actual paper focus on thermal properties of a sustainable lightweight concrete incorporating high volume of waste polypropylene aggregate as partial substitution of natural aggregate. In presented experiments a glass fiber reinforced polypropylene (GFPP) which is a by-product of PP tubes production, partially substituted fine natural silica aggregate in 10, 20, 30, 40 and 50 mass %. Results were compared with a reference concrete mix without plastic waste in order to quantify the effect of GFPP use on concrete properties. Main material physical parameters were studied (bulk density, matrix density without air content, and particle size distribution). Especially a thermal transport and storage properties of GFPP were examined in dependence on compaction time. For the developed lightweight concrete, thermal properties were accessed using transient impulse technique, where the measurement was done in dependence on moisture content (from the fully water saturated state to dry state). It was found that the tested lightweight concrete should be prospective construction material possessing improved thermal insulation function and the reuse of waste plastics in concrete composition was beneficial both from the environmental and financial point of view.

Lifestyle Behaviors in Metabolically Healthy and Unhealthy Overweight and Obese Women: A Preliminary Study.

PubMed

Camhi, Sarah M; Crouter, Scott E; Hayman, Laura L; Must, Aviva; Lichtenstein, Alice H

2015-01-01

Few studies have examined dietary data or objective measures of physical activity (PA) and sedentary behavior among metabolically healthy overweight/obese (MHO) and metabolically unhealthy overweight/obese (MUO). Thus, the purpose is to determine whether PA, sedentary behavior and/or diet differ between MHO and MUO in a sample of young women. Forty-six overweight/obese (BMI ≥25 kg/m2) African American and Caucasian women 19-35 years were classified by cardiometabolic risk factors, including elevated blood pressure, triglyceride, glucose and C-reactive protein, low high density lipoprotein, and insulin resistance (MUO ≥2; MHO, <2). Time (mins/day) in light, moderate, vigorous PA, and sedentary behavior were estimated using an accelerometer (≥3 days; ≥8 hrs wear time). Questionnaires were used to quantify sitting time, TV/computer use and usual daily activity. The Block Food Frequency Questionnaire assessed dietary food intake. Differences between MHO and MUO for lifestyle behaviors were tested with linear regression (continuous data) or logistic regression (categorical data) after adjusting for age, race, BMI, smoking and accelerometer wear and/or total kilocalories, as appropriate. Women were 26.7±4.7 years, with a mean BMI of 31.1±3.7 kg/m2, and 61% were African American. Compared to MUO (n = 9), MHO (n = 37; 80%) spent less mins/day in sedentary behavior (difference: -58.1±25.5, p = 0.02), more mins/day in light PA (difference: 38.2±16.1, p = 0.02), and had higher daily METs (difference: 0.21±0.09, p = 0.03). MHO had higher fiber intakes (g/day of total fiber, soluble fiber, fruit/vegetable fiber, bean fiber) and daily servings of vegetables; but lower daily dairy servings, saturated fat, monounsaturated fat and trans fats (g/day) compared to MUO. Compared to MUO, MHO young women demonstrate healthier lifestyle habits with less sedentary behavior, more time in light PA, and healthier dietary quality for fat type and fiber. Future studies are needed to replicate findings with larger samples that include men and women of diverse race/ethnic groups.

Nutritional intervention as an essential part of multiple sclerosis treatment?

PubMed

Penesová, A; Dean, Z; Kollár, B; Havranová, A; Imrich, R; Vlček, M; Rádiková, Ž

2018-05-10

Multiple sclerosis (MS) is a chronic inflammatory and demyelinating disease of the central nervous system. In addition to the genetic, epigenetic and immunological components, various other factors e.g. unhealthy dietary habits play a role in the MS pathogenesis. Dietary intervention is a highly appealing approach, as it presents a simple and relatively low risk method to potentially improve outcomes in patients with brain disorders in order to achieve remission and improvement of clinical status, well-being and life expectancy of patients with MS. The importance of saturated fat intake restriction for the clinical status improvement of MS patients was pointed for the first time in 1950s. Recently, decreased risk of first clinical diagnosis of CNS demyelination associated with higher intake of omega-3 polyunsaturated fatty acids particularly originating from fish was reported. Only few clinical trials have been performed to address the question of the role of dietary intervention, such is e.g. low saturated fat diet in MS treatment. This review summarizes current knowledge about the effect of different dietary approaches (diets low in saturated fat and dietary supplements such as fish oil, lipoic acid, omega-3 polyunsaturated fatty acids, seeds oils, high fiber diet, vitamin D, etc.) on neurological signs, patient's well-being, physical and inflammatory status. So far the results are not conclusive, therefore much more research is needed to confirm and to understand the effectiveness of these dietary interventions in the long term and well defined studies.

On Porosity Formation in Metal Matrix Composites Made with Dual-Scale Fiber Reinforcements Using Pressure Infiltration Process

NASA Astrophysics Data System (ADS)

Etemadi, Reihaneh; Pillai, Krishna M.; Rohatgi, Pradeep K.; Hamidi, Sajad Ahmad

2015-05-01

This is the first such study on porosity formation phenomena observed in dual-scale fiber preforms during the synthesis of metal matrix composites (MMCs) using the gas pressure infiltration process. In this paper, different mechanisms of porosity formation during pressure infiltration of Al-Si alloys into Nextel™ 3D-woven ceramic fabric reinforcements (a dual-porosity or dual-scale porous medium) are studied. The effect of processing conditions on porosity content of the ceramic fabric infiltrated by the alloys through the gas PIP (PIP stands for "Pressure Infiltration Process" in which liquid metal is injected under pressure into a mold packed with reinforcing fibers.) is investigated. Relative density (RD), defined as the ratio of the actual MMC density and the density obtained at ideal 100 pct saturation of the preform, was used to quantify the overall porosity. Increasing the infiltration temperature led to an increase in RD due to reduced viscosity of liquid metal and enhanced wettability leading to improved feedability of the liquid metal. Similarly, increasing the infiltration pressure led to enhanced penetration of fiber tows and resulted in higher RD and reduced porosity. For the first time, the modified Capillary number ( Ca*), which is found to predict formation of porosity in polymer matrix composites quite well, is employed to study porosity in MMCs made using PIP. It is observed that in the high Ca* regime which is common in PIP, the overall porosity shows a strong downward trend with increasing Ca*. In addition, the effect of matrix shrinkage on porosity content of the samples is studied through using a zero-shrinkage Al-Si alloy as the matrix; usage of this alloy as the matrix led to a reduction in porosity content.

Different evolution dynamics of vector solitons depending on their polarization states

NASA Astrophysics Data System (ADS)

Chen, Wei-Cheng; Chen, Guo-Jie

2014-03-01

There are three types of temporal evolution dynamics of vector solitons observed in a ring fiber laser with a semiconductor saturable absorption mirror (SESAM) as a mode-locker. It is found that the polarization property of vector solitons is an important factor for achieving different evolution dynamics. The vector soliton with a uniform polarization state across the whole pulse profile and zero polarization extinction ratio operates at a fundamental repetition rate with a single pulse profile. The elliptically polarized vector soliton with a larger polarization extinction ratio exhibits a harmonic pulse train. The soliton bunching with multi-peak structures exists between the above two states and shows elliptical polarization with a small polarization extinction ratio.

Control of twisted and coiled polymer actuator with anti-windup compensator

NASA Astrophysics Data System (ADS)

Suzuki, Motoya; Kamamichi, Norihiro

2018-07-01

A twisted and coiled polymer actuator (TCPA) is a novel soft actuator. It is fabricated by twisting nylon thread or fishing line. It can be thermally activated and has remarkable properties such as high power/mass ratio and large deformation. By applying conductive nylon fibers to the actuator, it can be electrically driven by Joule heating. However, if a controller of the actuator is designed without considering an input saturation, the control performance may be descended by windup phenomena. In this paper, to solve this problem, a feedback control with an anti-windup compensator is applied. The validity of the applied method is investigated through numerical simulations and experiments.

Method for making thin carbon foam electrodes

DOEpatents

Pekala, Richard W.; Mayer, Steven T.; Kaschmitter, James L.; Morrison, Robert L.

1999-01-01

A method for fabricating thin, flat carbon electrodes by infiltrating highly porous carbon papers, membranes, felts, metal fibers/powders, or fabrics with an appropriate carbon foam precursor material. The infiltrated carbon paper, for example, is then cured to form a gel-saturated carbon paper, which is subsequently dried and pyrolyzed to form a thin sheet of porous carbon. The material readily stays flat and flexible during curing and pyrolyzing to form thin sheets. Precursor materials include polyacrylonitrile (PAN), polymethylacrylonitrile (PMAN), resorcinol/formaldehyde, catechol/formaldehyde, phenol/formaldehyde, etc., or mixtures thereof. These thin films are ideal for use as high power and energy electrodes in batteries, capacitors, and fuel cells, and are potentially useful for capacitive deionization, filtration and catalysis.

FIBER AND INTEGRATED OPTICS. OTHER TOPICS IN QUANTUM ELECTRONICS: Determination of the saturation parameter in a fast-flow CO2 active medium

NASA Astrophysics Data System (ADS)

Lebedev, V. F.; Lysikov, A. Yu; Ryazanova, A. V.; Shalygin, S. V.

1990-05-01

A diagnostic method was developed for determination of such an important characteristic of a CO2 active medium as the energy stored in the vibrational degrees of freedom of molecules, which can be determined directly from the experimentally measured powers of probe beams without the need for any additional information on the medium and without any numerical calculations. Measurements were carried out using a real fast-flow system, which satisfied the conditions of validity of the proposed diagnostic method, and the correctness of the approach was confirmed. The results obtained demonstrated the efficiency of the excitation of the medium when the pump conditions were varied.

Electrospun Polyaniline/Polyethylene Oxide Nanofiber Field Effect Transistor

NASA Technical Reports Server (NTRS)

Pinto, N. J.; Johnson, A. T.; MacDiarmid, A. G.; Mueller, C. H.; Theofylaktos, N.; Robinson, D. C.; Miranda, F. A.

2003-01-01

We report on the observation of field effect transistor (FET) behavior in electrospun camphorsulfonic acid doped polyaniline(PANi)/polyethylene oxide(PE0) nanofibers. Saturation channel currents are observed at surprisingly low source/drain voltages. The hole mobility in the depletion regime is 1.4 x 10(exp -4) sq cm/V s while the 1-D charge density (at zero gate bias) is calculated to be approximately 1 hole per 50 two-ring repeat units of polyaniline, consistent with the rather high channel conductivity (approx. 10(exp -3) S/cm). Reducing or eliminating the PEO content in the fiber is expected to enhance device parameters. Electrospinning is thus proposed as a simple method of fabricating 1-D polymer FET's.

A photon-counting photodiode array detector for far ultraviolet (FUV) astronomy

NASA Technical Reports Server (NTRS)

Hartig, G. F.; Moos, H. W.; Pembroke, R.; Bowers, C.

1982-01-01

A compact, stable, single-stage intensified photodiode array detector designed for photon-counting, far ultraviolet astronomy applications employs a saturable, 'C'-type MCP (Galileo S. MCP 25-25) to produce high gain pulses with a narrowly peaked pulse height distribution. The P-20 output phosphor exhibits a very short decay time, due to the high current density of the electron pulses. This intensifier is being coupled to a self-scanning linear photodiode array which has a fiber optic input window which allows direct, rigid mechanical coupling with minimal light loss. The array was scanned at a 250 KHz pixel rate. The detector exhibits more than adequate signal-to-noise ratio for pulse counting and event location.

Oxygenation level and hemoglobin concentration in experimental tumor estimated by diffuse optical spectroscopy

NASA Astrophysics Data System (ADS)

Orlova, A. G.; Kirillin, M. Yu.; Volovetsky, A. B.; Shilyagina, N. Yu.; Sergeeva, E. A.; Golubiatnikov, G. Yu.; Turchin, I. V.

2017-07-01

Using diffuse optical spectroscopy the level of oxygenation and hemoglobin concentration in experimental tumor in comparison with normal muscle tissue of mice have been studied. Subcutaneously growing SKBR-3 was used as a tumor model. Continuous wave fiber probe diffuse optical spectroscopy system was employed. Optical properties extraction approach was based on diffusion approximation. Decreased blood oxygen saturation level and increased total hemoglobin content were demonstrated in the neoplasm. The main reason of such differences between tumor and norm was significant elevation of deoxyhemoglobin concentration in SKBR-3. The method can be useful for diagnosis of tumors as well as for study of blood flow parameters of tumor models with different angiogenic properties.

Adhesion properties in systems of laminated pigmented polymers, carbon-graphite fiber composite framework and titanium surfaces in implant suprastructures.

PubMed

Segerström, Susanna; Ruyter, I Eystein

2009-09-01

For long-term stability the adhering interfaces of an implant-retained supraconstruction of titanium/carbon-graphite fiber-reinforced (CGFR) polymer/opaquer layer/denture base polymer/denture teeth must function as a unity. The aim was to evaluate adhesion of CGFR polymer to a titanium surface or CGFR polymer to two different opaquer layers/with two denture base polymers. Titanium plates were surface-treated and silanized and combined with a bolt of CGFR polymer or denture base polymer (Probase Hot). Heat-polymerized plates of CGFR polymer (47 wt% fiber) based on poly(methyl methacrylate) and a copolymer matrix were treated with an opaquer (Sinfony or Ropak) before a denture base polymer bolt was attached (Probase Hot or Lucitone 199). All specimens were heat-polymerized, water saturated (200 days) and thermally cycled (5000 cycles, 5/55 degrees C) before shear bond testing. Silicatized titanium surfaces gave higher bond strength to CGFR polymer (16.2+/-2.34 and 18.6+/-1.32) MPa and cohesive fracture than a sandblasted surface (5.9+/-2.11) MPa where the fracture was adhesive. The opaquer Sinfony gave higher adhesion values and mainly cohesive fractures than the opaquer Ropak. Different surface treatments (roughened or polished) of the CGFR polymer had no effect on bond strength. The fracture surfaces of silicatized titanium/CGFR polymer/opaquer layer (Sinfony)/denture base polymers were mainly cohesive. A combination of these materials in an implant-retained supraconstruction is promising for in vivo evaluation.

Nutritional content of foods advertised during the television programs children watch most.

PubMed

Harrison, Kristen; Marske, Amy L

2005-09-01

We sought to code food (nutritional content and food type and eating occasion) and character (cartoon and live action) attributes of food advertisements airing during television programs heavily viewed by children, and to represent and evaluate the nutritional content of advertised foods in terms of the nutrition facts label. Food advertisements (n=426) aimed at general and child audiences were coded for food and character attributes. "Nutrition Facts" label data for advertised foods (n=275) were then analyzed. Convenience/fast foods and sweets comprised 83% of advertised foods. Snacktime eating was depicted more often than breakfast, lunch, and dinner combined. Apparent character body size was unrelated to eating behavior. A 2000-calorie diet of foods in the general-audience advertisements would exceed recommended daily values (RDVs) of total fat, saturated fat, and sodium. A similar diet of foods in the child-audience advertisements would exceed the sodium RDV and provide 171 g (nearly 1 cup) of added sugar. Snack, convenience, and fast foods and sweets continue to dominate food advertisements viewed by children. Advertised foods exceed RDVs of fat, saturated fat, and sodium, yet fail to provide RDVs of fiber and certain vitamins and minerals.

Abdominal obesity and type 2 diabetes in Asian Indians: dietary strategies including edible oils, cooking practices and sugar intake.

PubMed

Gulati, S; Misra, A

2017-07-01

Obesity and type 2 diabetes are increasing in rural and urban regions of South Asia including India. Pattern of fat deposition in abdomen, ectopic fat deposition (liver, pancreas) and also low lean mass are contributory to early-onset insulin resistance, dysmetabolic state and diabetes in Asian Indians. These metabolic perturbations are further exacerbated by changing lifestyle, diet urbanization, and mechanization. Important dietary imbalances include increasing use of oils containing high amount of trans fatty acids and saturated fats (partially hydrogenated vegetable oil, palmolein oil) use of deep frying method and reheating of oils for cooking, high intake of saturated fats, sugar and refined carbohydrates, low intake of protein, fiber and increasing intake of processed foods. Although dietary intervention trials are few; the data show that improving quality of carbohydrates (more complex carbohydrates), improving fat quality (more monounsaturated fatty acids and omega 3 polyunsaturated fatty acids) and increasing protein intake could improve blood glucose, serum insulin, lipids, inflammatory markers and hepatic fat, but more studies are needed. Finally, regulatory framework must be tightened to impose taxes on sugar-sweetened beverages, oils such as palmolein, and dietary fats and limit trans fats.

Nutritional analysis of a fiesta on Guam

PubMed Central

Paulino, Yvette C.; Leon Guerrero, Rachael T.; Aguon, Charissa M.

2009-01-01

Fiestas in Guam are celebrated year round, but documentation of the preparation and nutritional components of foods served at a traditional fiesta on Guam is limited. Food preparation was observed during a fiesta celebrated in the village of Sinajana, Guam. A food scale was used to weigh the ingredients of food dishes. Nutritional analysis software was used to determine the nutrient content of each food dish served. Of the thirty-four dishes that were prepared and served, 32 dishes were analyzed. These dishes comprised 609,210 kcal, 38,761 g protein, 42,883 g carbohydrates, 30,260 g total fat, 10,019 g saturated fat, and 1890 g dietary fiber. More than 95% of the food prepared was potentially consumed. Of the food potentially consumed, 24% of the energy was from protein, 29% of the energy was from carbohydrates, 45% of the energy was from total fat, and 15% of the energy was from saturated fat. Of the top 10 foods contributing the most energy, 8 were totche (fish and meat) dishes. The nutrient availability for fiesta-goers was estimated. The assessment of fiesta nutrient intake is recommended for future research. PMID:19756167

[Atherosclerosis and nutrition].

PubMed

Daubresse, J C

2000-09-01

Atherosclerosis is the main cause of mortality in industrialized countries and even in poorly developed ones. It is linked to age and gender and also to a number of well identified risk factors: lipids anomalies, arterial hypertension, diabetes, smoking and weight excess among others. Risk factors improvement significantly reduces cardiovascular events. It is evident that nutrition plays an important role as it can modulate the evolution of body weight and blood pressure. Nutrition is also able to reduce the prevalence and severity of hyperlipidemias and diabetes. Saturated fatty acids (excepted stearic acid), trans poly-unsaturated acids as well as cholesterol increase serum LDL-cholesterol. Mono- and poly-unsaturated and classical cis-mono-unsaturated acids do the opposite. N-3 poly-unsaturated acids reduce serum triglyceride levels and cardiovascular events. Carbohydrates with a low glycemic index are important determinants of serum HDL-cholesterol levels and reduce cardiovascular risk. Animal proteins bring essential amino-acids to the body but also saturated fats. It seems interesting to eat vegetal proteins among which those derived from soya look promising. Our diet will include enough fiber and phytosterols-containing margarines look interesting as well. Modest alcohol consumption improves cardiovascular mortality in the majority of the prospective studies.

Tunable passively Q-switched erbium-doped fiber laser with Chitosan/MoS2 saturable absorber

NASA Astrophysics Data System (ADS)

Ahmad, H.; Aidit, S. N.; Ooi, S. I.; Tiu, Z. C.

2018-07-01

Chitosan, an organic polymer derived from the outer skeletons of crustacean and in the cell wall of fungi is explored as polymer host to develop thin film saturable absorber (SA). As a polymer, Chitosan shows high thermal stability as well as significant transmission characteristics. The highly transparent polymer serves as a good host for SA materials, and a composite Chitosan/MoS2 thin film is demonstrated to successfully generate stable Q-switched lasing output at operating wavelength of 1561.5 nm. At maximum pump power of 280.5 mW, the generated pulse exhibits maximum pulse repetition rate and pulse energy of 79.4 kHz and 43.69 nJ respectively as well as minimum pulse width of 1.02 μs. The overall efficiency of the laser cavity with the Chitosan/MoS2 thin film SA is approximately 0.93%. These results reflect the outstanding performance of Chitosan/MoS2 SA as compared to other MoS2 SA prepared using mechanical exfoliation and optical deposition technique. Moreover, the Chitosan polymer is shown to be a highly potential host in the SA fabrication process due to its promising performance which is comparable to PVA.

Passive Q-switching of microchip lasers based on Ho:YAG ceramics.

PubMed

Lan, R; Loiko, P; Mateos, X; Wang, Y; Li, J; Pan, Y; Choi, S Y; Kim, M H; Rotermund, F; Yasukevich, A; Yumashev, K; Griebner, U; Petrov, V

2016-06-20

A Ho:YAG ceramic microchip laser pumped by a Tm fiber laser at 1910 nm is passively Q-switched by single- and multi-layer graphene, single-walled carbon nanotubes (SWCNTs), and Cr²⁺:ZnSe saturable absorbers (SAs). Employing SWCNTs, this laser generated an average power of 810 mW at 2090 nm with a slope efficiency of 68% and continuous wave to Q-switching conversion efficiency of 70%. The shortest pulse duration was 85 ns at a repetition rate of 165 kHz, and the pulse energy reached 4.9 μJ. The laser performance and pulse stability were superior compared to graphene SAs even for a different number of graphene layers (n=1 to 4). A model for the description of the Ho:YAG laser Q-switched by carbon nanostructures is presented. This modeling allowed us to estimate the saturation intensity for multi-layered graphene and SWCNT SAs to be 1.2±0.2 and 7±1  MW/cm², respectively. When using Cr²⁺:ZnSe, the Ho:YAG microchip laser generated 11 ns/25 μJ pulses at a repetition rate of 14.8 kHz.

Nutritional Content of Foods Advertised During the Television Programs Children Watch Most

PubMed Central

Harrison, Kristen; Marske, Amy L.

2005-01-01

Objectives. We sought to code food (nutritional content and food type and eating occasion) and character (cartoon and live action) attributes of food advertisements airing during television programs heavily viewed by children, and to represent and evaluate the nutritional content of advertised foods in terms of the nutrition facts label. Methods. Food advertisements (n=426) aimed at general and child audiences were coded for food and character attributes. “Nutrition Facts” label data for advertised foods (n=275) were then analyzed. Results. Convenience/fast foods and sweets comprised 83% of advertised foods. Snacktime eating was depicted more often than breakfast, lunch, and dinner combined. Apparent character body size was unrelated to eating behavior. A 2000-calorie diet of foods in the general-audience advertisements would exceed recommended daily values (RDVs) of total fat, saturated fat, and sodium. A similar diet of foods in the child-audience advertisements would exceed the sodium RDV and provide 171 g (nearly 1 cup) of added sugar. Conclusions. Snack, convenience, and fast foods and sweets continue to dominate food advertisements viewed by children. Advertised foods exceed RDVs of fat, saturated fat, and sodium, yet fail to provide RDVs of fiber and certain vitamins and minerals. PMID:16118368

[A study on residual strain of abdominal aortic aneurysm after intraperitoneal administration of saturated hydrogen saline in rats].

PubMed

Song, Yuxiang; Chen, Feng; Xiong, Jiang; Guo, Wei; Pan, Xiujie; Jia, Senhao; Liu, Jie

2013-07-01

By observation of the diameter, progression rate, wall thickness, and the opening angle of the abnormal aortic of abdominal aortic aneurysm (AAA) in rats, to observe the effect of saturated hydrogen saline on residual strain of AAA rats, and to investigate its inhibition effect on AAA formation. Twenty healthy male Sprague Dawley rats (weighing, 200-220 g) were randomly divided into 2 groups, which was made the AAA model by infiltration of the abdominal arota with 0.5 mol/L calcium chloride. Saturated hydrogen saline (5 mL/kg) or saline (5 mL/kg) was injected intraperitoneally in the experimental group or control group respectively, every day for 28 days. At 28 days, the diameter, progression rate, wall thickness, and opening angle of the abnormal aorta were mearsured. The aortic tissue was harvested for histological examination (HE staining and aldehyde-fuchsin staining). At 28 days after operation, the diameter of abnormal aorta in 2 groups were significantly higher than preoperative ones (P < 0.05), the progression rate in experimental group (65% +/- 15%) was significantly lower than that in control group (128% +/- 54%) (t=3.611, P=0.005). The opening angle and the wall thickness in experimental group were (88.78 +/- 29.20) degrees and (0.14 +/- 0.03) mm respectively, had significant differences when compared with the values in control group [(44.23 +/- 28.52) degrees and (0.36 +/- 0.05) mm respectively] (P < 0.01). The integrity and continuity of the aortic wall in experimental group were superior to that in the control group. Compared with the control group, the injury of elastic fiber in aortic wall and the infiltration of inflammation were all reduced. Saturated hydrogen saline can maintain good mechanical properties and reduce dilatation of the aorta by increasing residual strain and reducing the remodeling of it.

Trends in the nutritional content of television food advertisements seen by children in the United States: analyses by age, food categories, and companies.

PubMed

Powell, Lisa M; Schermbeck, Rebecca M; Szczypka, Glen; Chaloupka, Frank J; Braunschweig, Carol L

2011-12-01

To examine trends in children's exposure to food-related advertising on television by age, product category, and company. Nutritional content analysis using television ratings data for 2003, 2005, 2007, and 2009 for children. Annual age-specific television ratings data captured children's exposure to broadcast network, cable network, syndicated, and spot television food advertising from all (except Spanish-language) programming. Children aged 2 to 5 and 6 to 11 years. Main Exposure  Television ratings. Children's exposure to food-related advertising on television with nutritional assessments for food and beverage products for grams of saturated fat, sugar, and fiber and milligrams of sodium. Children aged 2 to 5 and 6 to 11 years saw, respectively, on average, 10.9 and 12.7 food-related television advertisements daily in 2009, down 17.8% and 6.9% from 2003. Exposure to food and beverage products high in saturated fat, sugar, or sodium fell 37.9% and 27.7% but fast-food advertising exposure increased by 21.1% and 30.8% among 2- to 5- and 6- to 11-year-olds, respectively, between 2003 and 2009. In 2009, 86% of ads seen by children were for products high in saturated fat, sugar, or sodium, down from 94% in 2003. Exposure to unhealthy food and beverage product advertisements has fallen, whereas exposure to fast-food ads increased from 2003 to 2009. By 2009, there was not a substantial improvement in the nutritional content of food and beverage advertisements that continued to be advertised and viewed on television by US children.

Fundus spectroscopy and studies in retinal oximetry using intravitreal illumination

NASA Astrophysics Data System (ADS)

Salyer, David Alan

This dissertation documents the development of a new illumination technique for use in the studies of retinal oximetry and fundus spectroscopy. Intravitreal illumination is a technique where the back of the eye is illuminated trans-sclerally using a scanning monochromator coupled into a fiber optic illuminator. Retinal oximetry is the process of measuring the oxygen saturation of blood contained in retinal vessels by quantitative measurement of the characteristic color shift seen as blood oxygen saturation changes from oxygenated blood (reddish) to deoxygenated blood (bluish). Retinal oximetry was first attempted in 1963 but due to a variety of problems with accuracy and difficulty of measurement, has not matured to the point of clinical acceptability or commercial viability. Accurate retinal oximetry relies in part on an adequate understanding of the spectral reflectance characteristics of the fundus. The use of intravitreal illumination allows new investigations into the spectral reflectance properties of the fundus. The results of much research in fundus reflectance and retinal oximetry is detailed in this document, providing new insight into both of these related fields of study. Intravitreal illumination has been used to study retinal vessel oximetry and fundus reflectometry resulting in several important findings that are presented in this document. Studies on enucleated swine eyes have provided new insight into the bidirectional reflectance distribution function of the fundus. Research on live swine has shown accurate measurement of retinal vessel oxygen saturation and provided the first in vivo spectral transmittance measurement of the sensory retina. A secondary discovery during this research suggests that vitrectomy alters the retinal vasculature, an finding that should spawn new research in its own right.

A rare polyglycine type II-like helix motif in naturally occurring proteins.

PubMed

Warkentin, Eberhard; Weidenweber, Sina; Schühle, Karola; Demmer, Ulrike; Heider, Johann; Ermler, Ulrich

2017-11-01

Common structural elements in proteins such as α-helices or β-sheets are characterized by uniformly repeating, energetically favorable main chain conformations which additionally exhibit a completely saturated hydrogen-bonding network of the main chain NH and CO groups. Although polyproline or polyglycine type II helices (PP II or PG II ) are frequently found in proteins, they are not considered as equivalent secondary structure elements because they do not form a similar self-contained hydrogen-bonding network of the main chain atoms. In this context our finding of an unusual motif of glycine-rich PG II -like helices in the structure of the acetophenone carboxylase core complex is of relevance. These PG II -like helices form hexagonal bundles which appear to fulfill the criterion of a (largely) saturated hydrogen-bonding network of the main-chain groups and therefore may be regarded in this sense as a new secondary structure element. It consists of a central PG II -like helix surrounded by six nearly parallel PG II -like helices in a hexagonal array, plus an additional PG II -like helix extending the array outwards. Very related structural elements have previously been found in synthetic polyglycine fibers. In both cases, all main chain NH and CO groups of the central PG II -helix are saturated by either intra- or intermolecular hydrogen-bonds, resulting in a self-contained hydrogen-bonding network. Similar, but incomplete PG II -helix patterns were also previously identified in a GTP-binding protein and an antifreeze protein. © 2017 Wiley Periodicals, Inc.

Saturable Absorption in 2D Ti3 C2 MXene Thin Films for Passive Photonic Diodes.

PubMed

Dong, Yongchang; Chertopalov, Sergii; Maleski, Kathleen; Anasori, Babak; Hu, Longyu; Bhattacharya, Sriparna; Rao, Apparao M; Gogotsi, Yury; Mochalin, Vadym N; Podila, Ramakrishna

2018-03-01

MXenes comprise a new class of 2D transition metal carbides, nitrides, and carbonitrides that exhibit unique light-matter interactions. Recently, 2D Ti 3 CNT x (T x represents functional groups such as OH and F) was found to exhibit nonlinear saturable absorption (SA) or increased transmittance at higher light fluences, which is useful for mode locking in fiber-based femtosecond lasers. However, the fundamental origin and thickness dependence of SA behavior in MXenes remain to be understood. 2D Ti 3 C 2 T x thin films of different thicknesses are fabricated using an interfacial film formation technique to systematically study their nonlinear optical properties. Using the open aperture Z-scan method, it is found that the SA behavior in Ti 3 C 2 T x MXene arises from plasmon-induced increase in the ground state absorption at photon energies above the threshold for free carrier oscillations. The saturation fluence and modulation depth of Ti 3 C 2 T x MXene is observed to be dependent on the film thickness. Unlike other 2D materials, Ti 3 C 2 T x is found to show higher threshold for light-induced damage with up to 50% increase in nonlinear transmittance. Lastly, building on the SA behavior of Ti 3 C 2 T x MXenes, a Ti 3 C 2 T x MXene-based photonic diode that breaks time-reversal symmetry to achieve nonreciprocal transmission of nanosecond laser pulses is demonstrated. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Randomization to plant-based dietary approaches leads to larger short-term improvements in Dietary Inflammatory Index scores and macronutrient intake compared with diets that contain meat.

PubMed

Turner-McGrievy, Gabrielle M; Wirth, Michael D; Shivappa, Nitin; Wingard, Ellen E; Fayad, Raja; Wilcox, Sara; Frongillo, Edward A; Hébert, James R

2015-02-01

Studies have examined nutrient differences among people following different plant-based diets. However, all of these studies have been observational. The aim of the present study was to examine differences in nutrient intake and Dietary Inflammatory Index (DII) scores among overweight and obese (body mass index 25.0-49.9 kg/m(2)) adults randomized to receive dietary instruction on a vegan (n = 12), vegetarian (n = 13), pescovegetarian (n = 13), semivegetarian (n = 13), or omnivorous (n = 12) diet during a 6-month randomized controlled trial. Nutrient intake, nutrient adequacy, and DII score were assessed via two 24-hour dietary recalls (Automated Self-Administered 24-Hour Dietary Recall) at baseline and at 2 and 6 months. Differences in nutrient intake and the DII were examined using general linear models with follow-up tests at each time point. We hypothesized that individuals randomized to the vegan diet would have lower DII scores and greater improvements in fiber, carbohydrate, fat, saturated fat, and cholesterol at both 2 and 6 months as compared with the other 4 diets. Participants randomized to the vegan diet had significantly greater changes in most macronutrients at both time points, including fat and saturated fat, as well as cholesterol and, at 2 months, fiber, as compared with most of the other diet groups (Ps < .05). Vegan, vegetarian, and pescovegetarian participants all saw significant improvements in the DII score as compared with semivegetarian participants at 2 months (Ps < .05) with no differences at 6 months. Given the greater impact on macronutrients and the DII during the short term, finding ways to provide support for adoption and maintenance of plant-based dietary approaches, such as vegan and vegetarian diets, should be given consideration. Copyright © 2015 Elsevier Inc. All rights reserved.

A Dietary Feedback System for the Delivery of Consistent Personalized Dietary Advice in the Web-Based Multicenter Food4Me Study.

PubMed

Forster, Hannah; Walsh, Marianne C; O'Donovan, Clare B; Woolhead, Clara; McGirr, Caroline; Daly, E J; O'Riordan, Richard; Celis-Morales, Carlos; Fallaize, Rosalind; Macready, Anna L; Marsaux, Cyril F M; Navas-Carretero, Santiago; San-Cristobal, Rodrigo; Kolossa, Silvia; Hartwig, Kai; Mavrogianni, Christina; Tsirigoti, Lydia; Lambrinou, Christina P; Godlewska, Magdalena; Surwiłło, Agnieszka; Gjelstad, Ingrid Merethe Fange; Drevon, Christian A; Manios, Yannis; Traczyk, Iwona; Martinez, J Alfredo; Saris, Wim H M; Daniel, Hannelore; Lovegrove, Julie A; Mathers, John C; Gibney, Michael J; Gibney, Eileen R; Brennan, Lorraine

2016-06-30

Despite numerous healthy eating campaigns, the prevalence of diets high in saturated fatty acids, sugar, and salt and low in fiber, fruit, and vegetables remains high. With more people than ever accessing the Internet, Web-based dietary assessment instruments have the potential to promote healthier dietary behaviors via personalized dietary advice. The objectives of this study were to develop a dietary feedback system for the delivery of consistent personalized dietary advice in a multicenter study and to examine the impact of automating the advice system. The development of the dietary feedback system included 4 components: (1) designing a system for categorizing nutritional intakes; (2) creating a method for prioritizing 3 nutrient-related goals for subsequent targeted dietary advice; (3) constructing decision tree algorithms linking data on nutritional intake to feedback messages; and (4) developing personal feedback reports. The system was used manually by researchers to provide personalized nutrition advice based on dietary assessment to 369 participants during the Food4Me randomized controlled trial, with an automated version developed on completion of the study. Saturated fatty acid, salt, and dietary fiber were most frequently selected as nutrient-related goals across the 7 centers. Average agreement between the manual and automated systems, in selecting 3 nutrient-related goals for personalized dietary advice across the centers, was highest for nutrient-related goals 1 and 2 and lower for goal 3, averaging at 92%, 87%, and 63%, respectively. Complete agreement between the 2 systems for feedback advice message selection averaged at 87% across the centers. The dietary feedback system was used to deliver personalized dietary advice within a multi-country study. Overall, there was good agreement between the manual and automated feedback systems, giving promise to the use of automated systems for personalizing dietary advice. Clinicaltrials.gov NCT01530139; https://clinicaltrials.gov/ct2/show/NCT01530139 (Archived by WebCite at http://www.webcitation.org/6ht5Dgj8I).

Modeled dietary impact of industry-wide food and beverage reformulations in the United States and France.

PubMed

Gressier, Mathilde; Privet, Lisa; Mathias, Kevin Clark; Vlassopoulos, Antonis; Vieux, Florent; Masset, Gabriel

2017-07-01

Background: Food reformulation has been identified as a strategy to improve nutritional intakes; however, little is known about the potential impact of industry-wide reformulations. Objective: The aim of the study was to model the dietary impact of food and beverage reformulation following the Nestlé Nutritional Profiling System (NNPS) standards for children, adolescents, and adults in the United States and France. Design: Dietary intakes of individuals aged ≥4 y were retrieved from nationally representative surveys: the US NHANES 2011-2012 ( n = 7456) and the French Individual and National Survey on Food Consumption ( n = 3330). The composition of all foods and beverages consumed were compared with the NNPS standards for energy, total and saturated fats, sodium, added sugars, protein, fiber, and calcium. Two scenarios were modeled. In the first, the nutrient content of foods and beverages was adjusted to the NNPS standards if they were not met. In the second, products not meeting the standards were replaced by the most nutritionally similar alternative meeting the standards from the same category. Dietary intakes were assessed against local nutrient recommendations, and analyses were stratified by body mass index and socioeconomic status. Results: Scenarios 1 and 2 showed reductions in US adults' mean daily energy (-88 and -225 kcal, respectively), saturated fats (-4.2, -6.9 g), sodium (-406, -324 mg), and added sugars (-29.4, -35.8 g). Similar trends were observed for US youth and in France. The effects on fiber and calcium were limited. In the United States, the social gradient of added sugars intake was attenuated in both scenarios compared with the baseline values. Conclusions: Potential industry-wide reformulation of the food supply could lead to higher compliance with recommendations in both the United States and France, and across all socioeconomic groups. NNPS standards seemed to be especially effective for nutrients consumed in excess. © 2017 American Society for Nutrition.

Association of mate tea (Ilex paraguariensis) intake and dietary intervention and effects on oxidative stress biomarkers of dyslipidemic subjects.

PubMed

Boaventura, Brunna Cristina Bremer; Di Pietro, Patrícia Faria; Stefanuto, Aliny; Klein, Graziela Alessandra; de Morais, Elayne Cristina; de Andrade, Fernanda; Wazlawik, Elisabeth; da Silva, Edson Luiz

2012-06-01

To evaluate the effect of long-term ingestion of mate tea, with or without dietary intervention, on the markers of oxidative stress in dyslipidemic individuals. Seventy-four dyslipidemic volunteers participated in this randomized clinical trial. Subjects were divided into three treatment groups: mate tea (MT), dietary intervention (DI), and mate tea with dietary intervention (MD). Biochemical and dietary variables were assessed at the beginning of the study (baseline) and after 20, 40, 60, and 90 d of treatment. Participants in the MT and MD groups consumed 1 L/d of mate tea. Those in the DI and MD groups were instructed to increase their intake of fruit, legumes and vegetables and decrease their consumption of foods rich in cholesterol and saturated and trans-fatty acids. Biomarkers of oxidative stress such as antioxidant capacity of serum (ferric reducing antioxidant potential assay), uric acid, reduced glutathione, paraoxonase-1 enzyme, lipid hydroperoxide (LOOH), and protein carbonyl were analyzed. Participants in the DI group showed a significant decrease in total fat and saturated fatty acid intakes. Those in the DI and MD groups presented a significant increase in vitamin C consumption. For all groups, there was a significant increase in ferric reducing antioxidant potential and reduced glutathione concentrations but no significant changes in LOOH, protein carbonyl, and paraoxonase-1 values. The reduced glutathione concentration was positively correlated with the consumption of monounsaturated fatty acids, fiber, and vitamin C, whereas levels of LOOH were inversely correlated with intakes of vitamin C and fiber. In addition, LOOH correlated positively with low-density lipoprotein cholesterol and inversely with high-density lipoprotein cholesterol, which had a positive association with paraoxonase-1. The ingestion of mate tea independently of the dietary intervention increased plasma and blood antioxidant protection in patients with dyslipidemia. Copyright © 2012 Elsevier Inc. All rights reserved.

Pulsatile Flow and Gas Transport of Blood over an Array of Cylinders

NASA Astrophysics Data System (ADS)

Chan, Kit Yan

2005-11-01

In the artificial lung, blood passes through an array of micro-fibers and the gas transfer is strongly dependent on the flow field. The blood flow is unsteady and pulsatile. We have numerically simulated pulsatile flow and gas transfer of blood (modeled as a Casson fluid) over arrays of cylindrical micro-fibers. Oxygen and carbon dioxide are assumed to be in local equilibrium with hemoglobin in blood; and the carbon dioxide facilitated oxygen transport is incorporated into the model by allowing the coupling of carbon dioxide partial pressure and oxygen saturation. The pulsatile flow inputs considered are the sinusoidal and the cardiac waveforms. The squared and staggered arrays of arrangement of the cylinders are considered in this study. Gas transport can be enhanced by: increasing the oscillation frequency; increasing the Reynolds number; increasing the oscillation amplitude; decreasing the void fraction; the use of the cardiac pulsatile input. The overall gas transport is greatly enhanced by the presence of hemoglobin in blood even though the non-Newtonian effect of blood tends to decrease the size and strength of vortices. The pressure drop is also presented as it is an important design parameter confronting the heart.

Optical fiber sensors based on novel polyimide for humidity monitoring of building materials

NASA Astrophysics Data System (ADS)

Chai, Jing; Liu, Qi; Liu, Jinxuan; Zhang, Dingding

2018-03-01

This paper presents novel preparation methods of polyimide and coupling agent, coated on the fiber Bragg grating (FBG) sensor for monitoring relative humidity (RH). The sensing mechanism that the volume change of the moisture-sensitive polyimide induces the shift of the Bragg wavelength of FBG is used in the RH sensor. The performance of the polymer-coated RH sensor was evaluated under laboratory conditions of temperature over a range of values (20.0-80.0 °C) and humidity over a range of RH values (25.0-95.0%). The time response and RH sensitivity of the sensor based on novel polyimide and coupling agent was improved, compared to the previous. A new packaged RH sensor was designed, which was used in detecting the moisture diffusion and evolutions inside of sample made of building materials which exposed to a controlled environment in the lab after casting. Relative humidity inside of sample with time was 100% in the first phase of vapor-saturated, slowly reduced in the latter phase. The results indicate the RH sensor developed provides a feasible method to detect the influence of environment on moisture inside the material in the drying process.

Bubble coalescence suppression driven carbon monoxide (CO)-water mass transfer increase by electrolyte addition in a hollow fiber membrane bioreactor (HFMBR) for microbial CO conversion to ethanol.

PubMed

Jang, Nulee; Yasin, Muhammad; Kang, Hyunsoo; Lee, Yeubin; Park, Gwon Woo; Park, Shinyoung; Chang, In Seop

2018-05-04

This study investigated the effects of electrolytes (CaCl 2 , K 2 HPO 4 , MgSO 4 , NaCl, and NH 4 Cl) on CO mass transfer and ethanol production in a HFMBR. The hollow fiber membranes (HFM) were found to generate tiny gas bubbles; the bubble coalescence was significantly suppressed in electrolyte solution. The volumetric gas-liquid mass transfer coefficients (k L a) increased up to 414% compared to the control. Saturated CO (C ∗ ) decreased as electrolyte concentrations increased. Overall, the maximum mass transfer rate (R max ) in electrolyte solution ranged from 106% to 339% of the value obtained in water. The electrolyte toxicity on cell growth was tested using Clostridium autoethanogenum. Most electrolytes, except for MgSO 4 , inhibited cell growth. The HFMBR operation using a medium containing 1% MgSO 4 achieved 119% ethanol production compared to that without electrolytes. Finally, a kinetic simulation using the parameters got from the 1% MgSO 4 medium predicted a higher ethanol production compared to the control. Copyright © 2018 Elsevier Ltd. All rights reserved.

Experimental demonstration of using divergence cost-function in SPGD algorithm for coherent beam combining with tip/tilt control.

PubMed

Geng, Chao; Luo, Wen; Tan, Yi; Liu, Hongmei; Mu, Jinbo; Li, Xinyang

2013-10-21

A novel approach of tip/tilt control by using divergence cost function in stochastic parallel gradient descent (SPGD) algorithm for coherent beam combining (CBC) is proposed and demonstrated experimentally in a seven-channel 2-W fiber amplifier array with both phase-locking and tip/tilt control, for the first time to our best knowledge. Compared with the conventional power-in-the-bucket (PIB) cost function for SPGD optimization, the tip/tilt control using divergence cost function ensures wider correction range, automatic switching control of program, and freedom of camera's intensity-saturation. Homemade piezoelectric-ring phase-modulator (PZT PM) and adaptive fiber-optics collimator (AFOC) are developed to correct piston- and tip/tilt-type aberrations, respectively. The PIB cost function is employed for phase-locking via maximization of SPGD optimization, while the divergence cost function is used for tip/tilt control via minimization. An average of 432-μrad of divergence metrics in open loop has decreased to 89-μrad when tip/tilt control implemented. In CBC, the power in the full width at half maximum (FWHM) of the main lobe increases by 32 times, and the phase residual error is less than λ/15.

Structural comparison of arabinoxylans from two barley side-stream fractions.

PubMed

Pitkänen, Leena; Tuomainen, Päivi; Virkki, Liisa; Aseyev, Vladimir; Tenkanen, Maija

2008-07-09

The structures of barley ( Hordeum vulgare) arabinoxylans isolated from two industrial side fractions, barley husks (BH) and barley fiber (BF), were characterized. Arabinoxylans were extracted with saturated barium hydroxide after enzymatic pretreatment. Barium hydroxide was selective toward arabinoxylans, and only a minor amount of glucose-containing material was coextracted. Acid methanolysis followed by gas chromatography, 1H NMR spectroscopy, and specific enzymatic treatments followed by anion exchange chromatography with pulse amperometric detection (HPAEC-PAD) revealed that the chemical structure of barley husk arabinoxylan (BHAX) clearly differed from that of barley fiber arabinoxylan (BFAX). BFAX was more branched, containing more beta-D-xylopyranosyl (beta-D-Xylp) residues carrying alpha-L-arabinofuranosyl (alpha-L-Araf) units at both O-2 and O-3 positions. BHAX, on the other hand, contained more 2-O-beta-D-Xyl p-alpha-L-Ara f substituents than BFAX. BHAX and BFAX also differed with respect to the hydrodynamic properties investigated with multidetector size exclusion chromatography. BFAX had a higher weight-average molar mass and larger hydrodynamic volume, the latter indicating less dense conformation than BHAX. Mn, Mw /Mn, Rh, and the Mark-Houwink a value were also determined for both arabinoxylans.

Overland flow dynamics through visual observation using time-lapse photographs

NASA Astrophysics Data System (ADS)

Silasari, Rasmiaditya; Blöschl, Günter

2016-04-01

Overland flow process on agricultural land is important to be investigated as it affects the stream discharge and water quality assessment. During rainfall events the formation of overland flow may happen through different processes (i.e. Hortonian or saturation excess overland flow) based on the governing soil hydraulic parameters (i.e. soil infiltration rate, soil water capacity). The dynamics of the soil water state and the processes will affect the surface runoff response which can be analyzed visually by observing the saturation patterns with a camera. Although visual observation was proven useful in laboratory experiments, the technique is not yet assessed for natural rainfall events. The aim of this work is to explore the use of time-lapse photographs of naturally occurring-saturation patterns in understanding the threshold processes of overland flow generation. The image processing produces orthographic projection of the saturation patterns which will be used to assess the dynamics of overland flow formation in relation with soil moisture state and rainfall magnitude. The camera observation was performed at Hydrological Open Air Laboratory (HOAL) catchment at Petzenkirchen, Lower Austria. The catchment covers an area of 66 ha dominated with agricultural land (87%). The mean annual precipitation and mean annual flow at catchment outlet are 750 mm and 4 l/s, respectively. The camera was set to observe the overland flow along a thalweg on an arable field which was drained in 1950s and has advantages of: (1) representing agricultural land as the dominant part of the catchment, (2) adjacent to the stream with clear visibility (no obstructing objects, such as trees), (3) drained area provides extra cases in understanding the response of tile drain outflow to overland flow formation and vice versa, and (4) in the vicinity of TDT soil moisture stations. The camera takes a picture with 1280 x 720 pixels resolution every minute and sends it directly in a PC via fiber-optic network. Exterior orientation is required to project the observed saturation patterns in the photographs onto orthographic map. This was done by georeferencing the on-field GPS points taken throughout the camera field of view to the orthographic map obtained from an airborne laser scanning (ALS) campaign. Based on the projected saturation patterns, the patterns dynamics were analyzed in relation to soil moisture state and rainfall magnitude for events in autumn and winter 2014. From the observed events during saturated soil condition, tile drain flow reacted within one hour after the rain started, while no sign of saturation pattern evolving into overland flow was observed. Within two hours after the rain started, overland flow was fully formed along the thalweg which flowed to the erosion gully and created signal at the discharge station almost immediately. From the surface roughness aspect, field management is an important factor of overland flow development as surface runoff was formed faster along the tractor tracks. In overall, time-lapse photographs have potentials to qualitatively assess the saturation patterns dynamics during rainfall events with high time resolution and wide area coverage.

Hydrodynamically-driven drug release during interstitial flow through hollow fibers implanted near lymphatics

PubMed Central

Dukhin, Stanislav S.; Labib, Mohamed E.

2016-01-01

Current drug delivery devices (DDD) are mainly based on the use of diffusion as the main transport process. Diffusion-driven processes can only achieve low release rate because diffusion is a slow process. This represents a serious obstacle in the realization of recent successes in the suppression of lymphatic metastasis and in the prevention of limb and organ transplant rejection. Surprisingly, it was overlooked that there is a more favorable drug release mode which can be achieved when a special DDD is implanted near lymphatics. This opportunity can be realized when the interstitial fluid flow penetrates a drug delivery device of proper design and allows such fluid to flow out of it. This design is based on hollow fibers loaded with drug and whose hydrodynamic permeability is much higher than that of the surrounding tissue. The latter is referred to as hollow fiber of high hydrodynamic permeability (HFHP). The interstitial flow easily penetrates the hollow fiber membrane as well as its lumen with a higher velocity than that in the adjacent tissue. The interstitial liquid stream entering the lumen becomes almost saturated with drug as it flows out of the HFHP. This is due to the drug powder dissolution in the lumens of HFHP which forms a strip of drug solution that crosses the interstitium and finally enters the lymphatics. This hydrodynamically-driven release (HDR) may exceed the concomitant diffusion-driven release (DDR) by one or even two orders of magnitude. The hydrodynamics of the two-compartment media is sufficient for developing the HDR theory which is detailed in this paper. Convective diffusion theory for two compartments (membrane of hollow fiber and adjacent tissue) is required for exact quantification when a small contribution of DDR to predominating HDR is present. Hence, modeling is important for HDR which would lead to establishing a new branch in physico-chemical hydrodynamics. The release rate achieved with the use of HFHP increases proportional to the number of hollow fibers in the fabric employed in drug delivery. Based on this contribution, it is now possible to simultaneously provide high release rates and long release durations, thus overcoming a fundamental limitation in drug delivery. Perhaps this breakthrough in long-term drug delivery has potential applications in targeting lymphatics and in treating cancer and cancer metastasis without causing the serious side effects of systemic drugs. PMID:28579697

Photo-thermal processing of semiconductor fibers and thin films

NASA Astrophysics Data System (ADS)

Gupta, Nishant

Furnace processing and rapid thermal processing (RTP) have been an integral part of several processing steps in semiconductor manufacturing. The performance of RTP techniques can be improved many times by exploiting quantum photo-effects of UV and vacuum ultraviolet (VUV) photons in thermal processing and this technique is known as rapid photo-thermal processing (RPP). As compared to furnace processing and RTP, RPP provides higher diffusion coefficient, lower stress and lower microscopic defects. In this work, a custom designed automated photo assisted processing system was built from individual parts and an incoherent light source. This photo-assisted processing system is used to anneal silica clad silicon fibers and deposit thin-films. To the best of our knowledge, incoherent light source based rapid photo-thermal processing (RPP) was used for the first time to anneal glass-clad silicon core optical fibers. X-ray diffraction examination, Raman spectroscopy and electrical measurements showed a considerable enhancement of structural and crystalline properties of RPP treated silicon fibers. Photons in UV and vacuum ultraviolet (VUV) regions play a very important role in improving the bulk and carrier transport properties of RPP-treated silicon optical fibers, and the resultant annealing permits a path forward to in situ enhancement of the structure and properties of these new crystalline core optical fibers. To explore further applications of RPP, thin-films of Calcium Copper Titanate (CaCu3Ti4O12) or CCTO and Copper (I) Oxide (Cu2O) were also deposited using photo-assisted metal-organic chemical vapor deposition (MOCVD) on Si/SiO2 and n-Si substrate respectively. CCTO is one of the most researched giant dielectric constant materials in recent years. The given photo-assisted MOCVD approach provided polycrystalline CCTO growth on a SiO2 surface with grain sizes as large as 410 nm. Copper (I) oxide (Cu2O) is a direct band gap semiconductor with p-type conductivity and is a potential candidate for multi-junction solar cells. X-ray diffraction study revealed a preferred orientation, as (200) oriented crystals of Cu2O are grown on both substrates. Also, electrical characterization of Cu2O/n-Si devices showed the lowest saturation current density of 1.5x10-12 A/cm 2 at zero bias. As a result, photo-assisted thermal processing has the potential of making the process more effective with enhanced device performance.

Low-frequency bias tone suppression of auditory-nerve responses to low-level clicks and tones.

PubMed

Nam, Hui; Guinan, John J

2016-11-01

We used low-frequency "bias" tones (BT's) to explore whether click and tone responses are affected in the same way by cochlear active processes. In nonlinear systems the responses to clicks are not always simply related to the responses to tones. Cochlear amplifier gain depends on the incremental slope of the outer-hair-cell (OHC) stereocilia mechano-electric transduction (MET) function. BTs transiently change the operating-point of OHC MET channels and can suppress cochlear-amplifier gain by pushing OHC METs into low-slope saturation regions. BT effects on single auditory-nerve (AN) fibers have been studied on tone responses but not on click responses. We recorded from AN fibers in anesthetized cats and compared tone and click responses using 50 Hz BTs at 70-120 dB SPL to manipulate OHC stereocilia position. BTs can also excite and thereby obscure the BT suppression. We measured AN-fiber response synchrony to BTs alone so that we could exclude suppression measurements when the BT synchrony might obscure the suppression. BT suppression of low-level tone and click responses followed the traditional pattern of twice-a-BT-cycle suppression with more suppression at one phase than the other. The major suppression phases of most fibers were tightly grouped with little difference between click and tone suppressions, which is consistent with low-level click and tone responses being amplified in the same way. The data are also consistent with the operating point of the OHC MET function varying smoothly from symmetric in the base to offset in the apex, and, in contrast, with the IHC MET function being offset throughout the cochlea. As previously reported, bias-tones presented alone excited AN fibers at one or more phases, a phenomena termed "peak splitting" with most BT excitation phases ∼¼ cycle before or after the major suppression phase. We explain peak splitting as being due to distortion in multiple fluid drives to inner-hair-cell stereocilia. Copyright © 2016 Elsevier B.V. All rights reserved.

A High Fiber and Vegetable Protein Diet is Associated with Low Lumbar Bone Mineral Density in Young Oligo-amenorrheic Athletes

PubMed Central

Barron, Elizabeth; Sokoloff, Natalia Cano; Maffazioli, Giovana D. N.; Ackerman, Kathryn E.; Woolley, Ryan; Holmes, Tara M.; Anderson, Ellen J.; Misra, Madhusmita

2015-01-01

Background Associations of bone mineral density (BMD) with specific food components, including dietary fiber and isoflavones (that have a negative association with serum estrogen), are unclear and need to be determined, particularly in a population more likely to consume large amounts of these nutrients (such as young athletes). Objective To determine dietary intake of specific food components in oligo-amenorrheic athletes (OA) compared to eumenorrheic athletes (EA) and non-athletes (NA), and associations of the dietary intake of these nutrients with lumbar spine BMD. Design and Subjects This cross-sectional study evaluated 68 OA, 24 EA, and 26 NA 14–23 years old. Measurements included four-day food records (assessed using Nutrient Data System for Research software), a DXA scan evaluating lumbar spine BMD and body composition, and hormone levels. Multivariate analysis was used to estimate associations of nutrients with lumbar spine BMD. Results Compared with EA and NA, OA had higher intake of fiber, phytic acid, and vegetable protein (p<0.0001 for all). Intake of isoflavones, genistein and daidzein, was higher in OA than NA (p=0.003 and 0.0002 respectively). OA had lower consumption of energy from saturated fatty acids (%SFA) than NA (p=0.002). After controlling for confounders such as body weight, menstrual status (indicative of estrogen status), calcium intake, and serum vitamin D (known BMD determinants), lumbar spine BMD Z-scores were inversely associated with dietary fiber [β coefficient (β)= −0.30; p=0.01], vegetable protein (β = −0.28, p=0.02), phytic acid (β = −0.27, p=0.02), genistein (β = −0.25, p=0.01), and daidzein (β = −0.24, p=0.01), and positively with %SFA (β =0.32, p=0.0006)]. Conclusions Compared to EA and NA, OA had a higher dietary intake of fiber, vegetable protein and phytic acid, which were inversely associated with lumbar spine BMD Z-scores. Further studies are needed to assess dietary recommendations for OA to optimize bone accrual. PMID:26686817

Method for making thin carbon foam electrodes

DOEpatents

Pekala, R.W.; Mayer, S.T.; Kaschmitter, J.L.; Morrison, R.L.

1999-08-03

A method for fabricating thin, flat carbon electrodes by infiltrating highly porous carbon papers, membranes, felts, metal fibers/powders, or fabrics with an appropriate carbon foam precursor material is disclosed. The infiltrated carbon paper, for example, is then cured to form a gel-saturated carbon paper, which is subsequently dried and pyrolyzed to form a thin sheet of porous carbon. The material readily stays flat and flexible during curing and pyrolyzing to form thin sheets. Precursor materials include polyacrylonitrile (PAN), polymethylacrylonitrile (PMAN), resorcinol/formaldehyde, catechol/formaldehyde, phenol/formaldehyde, etc., or mixtures thereof. These thin films are ideal for use as high power and energy electrodes in batteries, capacitors, and fuel cells, and are potentially useful for capacitive deionization, filtration and catalysis.

Noninvasive diagnostics of skin microphysical parameters based on spatially resolved diffuse reflectance spectroscopy

NASA Astrophysics Data System (ADS)

Lisenko, S. A.; Kugeiko, M. M.

2013-01-01

The ability to determine noninvasively microphysical parameters (MPPs) of skin characteristic of malignant melanoma was demonstrated. The MPPs were the melanin content in dermis, saturation of tissue with blood vessels, and concentration and effective size of tissue scatterers. The proposed method was based on spatially resolved spectral measurements of skin diffuse reflectance and multiple regressions between linearly independent measurement components and skin MPPs. The regressions were established by modeling radiation transfer in skin with a wide variation of its MPPs. Errors in the determination of skin MPPs were estimated using fiber-optic measurements of its diffuse reflectance at wavelengths of commercially available semiconductor diode lasers (578, 625, 660, 760, and 806 nm) at source-detector separations of 0.23-1.38 mm.

Wide range operation of regenerative optical parametric wavelength converter using ASE-degraded 43-Gb/s RZ-DPSK signals.

PubMed

Gao, Mingyi; Kurumida, Junya; Namiki, Shu

2011-11-07

For sustainable growth of the Internet, wavelength-tunable optical regeneration is the key to scaling up high energy-efficiency dynamic optical path networks while keeping the flexibility of the network. Wavelength-tunable optical parametric regenerator (T-OPR) based on the gain saturation effect of parametric amplification in a highly nonlinear fiber is promising for noise reduction in phase-shift keying signals. In this paper, we experimentally evaluated the T-OPR performance for ASE-degraded 43-Gb/s RZ-DPSK signals over a 20-nm input wavelength range between 1527 nm and 1547 nm. As a result, we achieved improved power penalty performance for the regenerated idler with a proper pump power range.

Unidirectional, dual-comb lasing under multiple pulse formation mechanisms in a passively mode-locked fiber ring laser.

PubMed

Liu, Ya; Zhao, Xin; Hu, Guoqing; Li, Cui; Zhao, Bofeng; Zheng, Zheng

2016-09-19

Dual-comb lasers simultaneously generating asynchronous ultrashort pulses could be an intriguing alternative to the current dual-laser comb source. When generated through a common light path, the low common-mode noises and good coherence between the pulse trains could be realized. Here we demonstrate the completely common-path, unidirectional dual-comb lasing using a carbon nanotube saturable absorber with additional pulse narrowing and broadening mechanisms. The interactions between multiple soliton formation mechanisms result in bifurcation into unusual two-pulse states with pulses of four-fold bandwidth difference and tens-of-Hz repetition rate difference. Coherence between the pulses is verified by the asynchronous cross-sampling and dual-comb spectroscopy measurements.