Study on Size-Dependent Young’s Modulus of a Silicon Nano beam by Molecular Dynamics Simulation

International Nuclear Information System (INIS)

Yu, H.; Sun, C.; Zhang, W.W.; Lei, S.Y.; Huang, K.A.

2013-01-01

Young’s modulus of a silicon nano beam with a rectangular cross-section is studied by molecular dynamics method. Dynamic simulations are performed for doubly clamped silicon nano beams with lengths ranging from 4.888 to 12.491 nm and cross-sections ranging from 1.22 nm ×1.22 nm to 3.39 nm × 3.39 nm. The results show that Young’s moduli of such small silicon nano beams are much higher than the value of Young’s modulus for bulk silicon. Moreover, the resonant frequency and Young’s modulus of the Si nano beam are strongly dependent not only on the size of the nano beam but also on surface effects. Young’s modulus increases significantly with the decreasing of the thickness of the silicon nano beam. This result qualitatively agrees with one of the conclusions based on a semi continuum model, in which the surface relaxation and the surface tension were taken into consideration. The impacts of the surface reconstruction with (2 ×1) dimmers on the resonant frequency and Young’s modulus are studied in this paper too. It is shown that the surface reconstruction makes the silicon nano beam stiffer than the one without the surface reconstruction, resulting in a higher resonant frequency and a larger Young’s modulus

An electron beam linear scanning mode for industrial limited-angle nano-computed tomography

Science.gov (United States)

Wang, Chengxiang; Zeng, Li; Yu, Wei; Zhang, Lingli; Guo, Yumeng; Gong, Changcheng

2018-01-01

Nano-computed tomography (nano-CT), which utilizes X-rays to research the inner structure of some small objects and has been widely utilized in biomedical research, electronic technology, geology, material sciences, etc., is a high spatial resolution and non-destructive research technique. A traditional nano-CT scanning model with a very high mechanical precision and stability of object manipulator, which is difficult to reach when the scanned object is continuously rotated, is required for high resolution imaging. To reduce the scanning time and attain a stable and high resolution imaging in industrial non-destructive testing, we study an electron beam linear scanning mode of nano-CT system that can avoid mechanical vibration and object movement caused by the continuously rotated object. Furthermore, to further save the scanning time and study how small the scanning range could be considered with acceptable spatial resolution, an alternating iterative algorithm based on ℓ0 minimization is utilized to limited-angle nano-CT reconstruction problem with the electron beam linear scanning mode. The experimental results confirm the feasibility of the electron beam linear scanning mode of nano-CT system.

Producing nano-grained and Al-enriched surface microstructure on AZ91 magnesium alloy by high current pulsed electron beam treatment

Energy Technology Data Exchange (ETDEWEB)

Hao, Shengzhi, E-mail: ebeam@dlut.edu.cn; Li, Mincai

2016-05-15

Highlights: • HCPEB surface treatment was conducted on AZ91 magnesium alloy. • Surface modified microstructure and phase composition were characterized. • Preferential evaporation of Mg and dissolution of Mg{sub 17}Al{sub 12} phase occurred. • Nano-grained and Al-enriched surface layer was produced of depth ∼8 μm. • Surface microhardness and corrosion resistance were improved simultaneously. - Abstract: Surface treatment of AZ91 magnesium alloy was carried out by high current pulsed electron beam (HCPEB) with accelerating voltage 27 kV and energy density 3 J/cm{sup 2}. The surface microstructure and phase composition were characterized by using optical microscope (OM), X-ray diffraction (XRD), and scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS). The surface microhardness and corrosion resistance were measured. Under HCPEB treatments, the preferential evaporation of Mg element occurred intensively on irradiated surface and the initial large Mg{sub 17}Al{sub 12} phases were dissolved. The nano-grained and Al-enriched surface modified layer was ultimately formed of depth ∼8 μm. According to the testing results, the surface microhardness increased from 63 to 141 HK after 30 pulses of HCPEB treatment, while the best improvement of corrosion resistance was obtained by 15 pulses of HCPEB treatment with a cathodic current density decreased by two orders of magnitude as compared with the initial AZ91 sample.

Effect of cAMP on short-circuit current in isolated human ciliary body.

Science.gov (United States)

Wu, Ren-yi; Ma, Ning; Hu, Qian-qian

2013-07-01

Cyclic adenosine monophosphate (cAMP) could activate chloride channels in bovine ciliary body and trigger an increase in the ionic current (short-circuit current, Isc) across the ciliary processes in pigs. The purpose of this study was to investigate how cAMP modulates Isc in isolated human ciliary processes and the possible involvement of chloride transport across the tissue in cAMP-induced Isc change. In an Ussing-type chamber system, the Isc changes induced by the cAMP analogue 8-bromo-cAMP and an adenylyl cyclase activator forskolin in isolated human ciliary processes were assessed. The involvement of Cl(-) component in the bath solution was investigated. The effect of Cl(-) channel (10 µmol/L niflumic acid and 1 mmol/L 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS)), K(+) channel (10 mmol/L tetraethylammonium chloride (TEA)), or Na(+) channel blockers (1 mmol/L amiloride) on 8-bromo-cAMP-induced Isc change was also studied. Dose-dependently, 8-bromo-cAMP (10 nmol/L-30 µmol/L) or forskolin (10 nmol/L-3 µmol/L) increased Isc across the ciliary processes with an increase in negative potential difference on the non-pigmented epithelium (NPE) side of the tissue. Isc increase induced by 8-bromo-cAMP was more pronounced when the drug was applied on the NPE side than on the pigmented epithelium side. When the tissue was bathed in low Cl(-) solutions, the Isc increase was significantly inhibited. Finally, niflumic acid and DIDS, but not TEA or amiloride, significantly prevented the Isc increase induced by 8-bromo-cAMP. cAMP stimulates stroma-to-aqueous anionic transport in isolated human ciliary processes. Chloride is likely to be among the ions, the transportation of which across the tissue is triggered by cAMP, suggesting the potential role of cAMP in the process of aqueous humor formation in human eyes.

Self-Assembled Gold Nano-Ripple Formation by Gas Cluster Ion Beam Bombardment.

Science.gov (United States)

Tilakaratne, Buddhi P; Chen, Quark Y; Chu, Wei-Kan

2017-09-08

In this study, we used a 30 keV argon cluster ion beam bombardment to investigate the dynamic processes during nano-ripple formation on gold surfaces. Atomic force microscope analysis shows that the gold surface has maximum roughness at an incident angle of 60° from the surface normal; moreover, at this angle, and for an applied fluence of 3 × 10 16 clusters/cm², the aspect ratio of the nano-ripple pattern is in the range of ~50%. Rutherford backscattering spectrometry analysis reveals a formation of a surface gradient due to prolonged gas cluster ion bombardment, although the surface roughness remains consistent throughout the bombarded surface area. As a result, significant mass redistribution is triggered by gas cluster ion beam bombardment at room temperature. Where mass redistribution is responsible for nano-ripple formation, the surface erosion process refines the formed nano-ripple structures.

Focused ion beam patterned Hall nano-sensors

International Nuclear Information System (INIS)

Candini, A.; Gazzadi, G.C.; Di Bona, A.; Affronte, M.; Ercolani, D.; Biasiol, G.; Sorba, L.

2007-01-01

By means of focused ion beam milling, we fabricate Hall magnetometers with active areas as small as 100x100nm 2 . The constituent material can either be metallic (Au), semimetallic (Bi) or doped bulk semiconducting (Si doped GaAs). We experimentally show that Au nano-probes can work from room temperature down to liquid helium with magnetic flux sensitivity -1 Φ 0

Brightness enhancement of plasma ion source by utilizing anode spot for nano applications

International Nuclear Information System (INIS)

Park, Yeong-Shin; Lee, Yuna; Chung, Kyoung-Jae; Hwang, Y. S.; Kim, Yoon-Jae; Park, Man-Jin; Moon, Dae Won

2012-01-01

Anode spots are known as additional discharges on positively biased electrode immersed in plasmas. The anode spot plasma ion source (ASPIS) has been investigated as a high brightness ion source for nano applications such as focused ion beam (FIB) and nano medium energy ion scattering (nano-MEIS). The generation of anode spot is found to enhance brightness of ion beam since the anode spot increases plasma density near the extraction aperture. Brightness of the ASPIS has been estimated from measurement of emittance for total ion beam extracted through sub-mm aperture. The ASPIS is installed to the FIB system. Currents and diameters of the focused beams with/without anode spot are measured and compared. As the anode spot is turned on, the enhancement of beam current is observed at fixed diameter of the focused ion beam. Consequently, the brightness of the focused ion beam is enhanced as well. For argon ion beam, the maximum normalized brightness of 12 300 A/m 2 SrV is acquired. The ASPIS is applied to nano-MEIS as well. The ASPIS is found to increase the beam current density and the power efficiency of the ion source for nano-MEIS. From the present study, it is shown that the ASPIS can enhance the performance of devices for nano applications.

Nonlinear current-voltage characteristics of WO3-x nano-/micro-rods

Science.gov (United States)

Shen, Zhenguang; Peng, Zhijian; Zhao, Zengying; Fu, Xiuli

2018-04-01

A series of crystalline tungsten oxide nano-/micro-rods with different compositions of WO3, WO2.90, W19O55 (WO2.89) and W18O49 (WO2.72) but identical morphology feature were first prepared. Then, various nanoscaled electrical devices were fabricated from them by micro-fabrication through a focused ion beam technique. Interestingly, the devices from the oxygen-deficient WO3-x display significantly nonlinear current-voltage characteristics. The calculated nonlinear coefficients of the WO2.90, WO2.83, and WO2.72 varistors are 2.52, 3.32 and 4.91, respectively. The breakdown voltage of the WO2.90, WO2.83, and WO2.72 varistors are 1.93, 1.28 and 0.93 V, respectively. Such WO3-x nano-varistors might be promising for low-voltage electrical/electronic devices.

Production of a high-current microsecond electron beam with a large cross section

International Nuclear Information System (INIS)

Abdullin, E.N.; Belomytsev, S.Ya.; Bugaev, S.P.; Gorbachev, S.I.; Zaslavskii, V.M.; Zorin, V.P.; Koval'chuk, B.M.; Loginov, S.V.; Matyukov, Yu.N.; Rasputin, R.M.; Tolkachev, V.S.; Shchanin, P.M.

1991-01-01

Obtaining high-current wide-aperture electron beams is an important problem in the development of laser technology for controlled nuclear fusion and for solving ecological and technological problems. The main scheme for producing such beams involves the use of generators with intermediate energy storage devices and burst-emission vacuum diodes. Beam pinching is prevented by using an external magnetic field or sectioning the diode into magnetically insulated diodes with currents lower than the limiting current. The length of the electron-current pulse varies from tens to hundreds of nano-seconds and is limited by the parameters of the intermediate storage device. Here the authors study the formation of a high-current electron beam with a square cross section and a current of the order of the limiting current of the diode in the absence of an external magnetic field as well as a 'fast' storage device in the power supply circuit. These conditions as a whole correspond to a simpler electron-source circuit, but the beam forming becomes more complicated. The reason for this is that there is no external magnetic field and that the role of plasma processes in the diode is enhanced by the greater length of the electron-current pulses

Beyond Snel's law: Refraction of a nano-beam of light

International Nuclear Information System (INIS)

Sun Wenbo; Videen, Gorden; Lin Bing; Hu Yongxiang; Fu Qiang

2011-01-01

The refraction of a localized narrow beam is significantly different from that of a plane wave. As the beam width decreases to be in the order of the wavelength, the refraction behavior deviates noticeably from Snel's law, and when the width of a light beam is smaller than about one fifth of the wavelength of the incident light, finite-difference time-domain simulations demonstrate that refraction becomes negligible. That is, the narrow light beam retains its propagation direction even after entering another medium at an oblique angle. The result reveals novel features of nano-beams and may have applications in precise biomedical measurement or micro optical device.

LANSCE beam current limiter

International Nuclear Information System (INIS)

Gallegos, F.R.

1996-01-01

The Radiation Security System (RSS) at the Los Alamos Neutron Science Center (LANSCE) provides personnel protection from prompt radiation due to accelerated beam. Active instrumentation, such as the Beam Current Limiter, is a component of the RSS. The current limiter is designed to limit the average current in a beam line below a specific level, thus minimizing the maximum current available for a beam spill accident. The beam current limiter is a self-contained, electrically isolated toroidal beam transformer which continuously monitors beam current. It is designed as fail-safe instrumentation. The design philosophy, hardware design, operation, and limitations of the device are described

A LVDT conditioner for the beam profile monitors of the AmPS

International Nuclear Information System (INIS)

Es, J.T. van; Trigt, J.H. van.

1991-01-01

A LVDT (Linear Variable Differential Transformer) is a transducer for localization. Because of its applied materials, its construction and the absence of bearings etc. the instrument is suitable to be applied in locations where radioactive radiation is present. In order to obtain information about the position of the iron core in the transducer, a conditioner is needed. In 1977 by Digel a conditioner has been developed for the beam profile monitors (moving wire) of MEA because the 'market' could not meet the requirements then. Nowadays the 'market' offers i.c.'s which can take over the work of the Eurocard developed then. Digel has investigated them in order to see if they are applicable for the beam profile monitors of AmPS. (author). 5 refs.; 7 figs.; 13 tabs

Brightness enhancement of plasma ion source by utilizing anode spot for nano applications

Energy Technology Data Exchange (ETDEWEB)

Park, Yeong-Shin; Lee, Yuna; Chung, Kyoung-Jae; Hwang, Y. S. [Department of Nuclear Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of); Kim, Yoon-Jae [Samsung Electronics Co. Ltd., Gyeonggi 445-701 (Korea, Republic of); Park, Man-Jin [Research Institute of Nano Manufacturing System, Seoul National University of Science and Technology, Seoul 139-743 (Korea, Republic of); Moon, Dae Won [Nanobio Fusion Research Center, Korea Research Institute of Standards and Science, Daejeon 305-600 (Korea, Republic of)

2012-02-15

Anode spots are known as additional discharges on positively biased electrode immersed in plasmas. The anode spot plasma ion source (ASPIS) has been investigated as a high brightness ion source for nano applications such as focused ion beam (FIB) and nano medium energy ion scattering (nano-MEIS). The generation of anode spot is found to enhance brightness of ion beam since the anode spot increases plasma density near the extraction aperture. Brightness of the ASPIS has been estimated from measurement of emittance for total ion beam extracted through sub-mm aperture. The ASPIS is installed to the FIB system. Currents and diameters of the focused beams with/without anode spot are measured and compared. As the anode spot is turned on, the enhancement of beam current is observed at fixed diameter of the focused ion beam. Consequently, the brightness of the focused ion beam is enhanced as well. For argon ion beam, the maximum normalized brightness of 12 300 A/m{sup 2} SrV is acquired. The ASPIS is applied to nano-MEIS as well. The ASPIS is found to increase the beam current density and the power efficiency of the ion source for nano-MEIS. From the present study, it is shown that the ASPIS can enhance the performance of devices for nano applications.

cAMP Stimulates Transepithelial Short-Circuit Current and Fluid Transport Across Porcine Ciliary Epithelium.

Science.gov (United States)

Cheng, Angela King-Wah; Civan, Mortimer M; To, Chi-Ho; Do, Chi-Wai

2016-12-01

To investigate the effects of cAMP on transepithelial electrical parameters and fluid transport across porcine ciliary epithelium. Transepithelial electrical parameters were determined by mounting freshly isolated porcine ciliary epithelium in a modified Ussing chamber. Similarly, fluid movement across intact ciliary body was measured with a custom-made fluid flow chamber. Addition of 1, 10, and 100 μM 8-Br-cAMP (cAMP) to the aqueous side (nonpigmented ciliary epithelium, NPE) induced a sustained increase in short-circuit current (Isc). Addition of niflumic acid (NFA) to the aqueous surface effectively blocked the cAMP-induced Isc stimulation. The administration of cAMP to the stromal side (pigmented ciliary epithelium, PE) triggered a significant stimulation of Isc only at 100 μM. No additive effect was observed with bilateral application of cAMP. Likewise, forskolin caused a significant stimulation of Isc when applied to the aqueous side. Concomitantly, cAMP and forskolin increased fluid transport across porcine ciliary epithelium, and this stimulation was effectively inhibited by aqueous NFA. Depleting Cl- in the bathing solution abolished the baseline Isc and inhibited the subsequent stimulation by cAMP. Pretreatment with protein kinase A (PKA) blockers (H89/KT5720) significantly inhibited the cAMP- and forskolin-induced Isc responses. Our results suggest that cAMP triggers a sustained stimulation of Cl- and fluid transport across porcine ciliary epithelium; Cl- channels in the NPE cells are potentially a cellular site for this PKA-sensitive cAMP-mediated response.

Beam instrumentation for the BNL Heavy Ion Transfer Line

International Nuclear Information System (INIS)

Witkover, R.L.; Buxton, W.; Castillo, V.; Feigenbaum, I.; Lazos, A.; Li, Z.G.; Smith, G.; Stoehr, R.

1987-01-01

The Heavy Ion Transfer Line (HITL) was constructed to transport beams from the BNL Tandem Van de Graaff (TVDG) to be injected into the AGS. Because the beam line is approximately 2000 feet long and the particle rigidity is so low, 20 beam monitor boxes were placed along the line. The intensity ranges from 1 to 100 nanoAmps for the dc trace beam used for line set-up, to over 100 μA for the pulsed beam to be injected into the AGS. Profiles are measured using multiwire arrays (HARPS) while Faraday cups and beam transformers monitor the intensity. The electronics stations are operated through 3 Instrumentation Controllers networked to Apollo workstations in the TVDG and AGS control rooms. Details of the detectors and electronics designs and performance will be given

Low current beam techniques

Energy Technology Data Exchange (ETDEWEB)

Saint, A.; Laird, J.S.; Bardos, R.A.; Legge, G.J.F. [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Nishijima, T.; Sekiguchi, H. [Electrotechnical Laboratory, Tsukuba (Japan).

1993-12-31

Since the development of Scanning Transmission Microscopy (STIM) imaging in 1983 many low current beam techniques have been developed for the scanning (ion) microprobe. These include STIM tomography, Ion Beam Induced Current, Ion Beam Micromachining and Microlithography and Ionoluminense. Most of these techniques utilise beam currents of 10{sup -15} A down to single ions controlled by beam switching techniques This paper will discuss some of the low beam current techniques mentioned above, and indicate, some of their recent applications at MARC. A new STIM technique will be introduced that can be used to obtain Z-contrast with STIM resolution. 4 refs., 3 figs.

Low current beam techniques

Energy Technology Data Exchange (ETDEWEB)

Saint, A; Laird, J S; Bardos, R A; Legge, G J.F. [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Nishijima, T; Sekiguchi, H [Electrotechnical Laboratory, Tsukuba (Japan).

1994-12-31

Since the development of Scanning Transmission Microscopy (STIM) imaging in 1983 many low current beam techniques have been developed for the scanning (ion) microprobe. These include STIM tomography, Ion Beam Induced Current, Ion Beam Micromachining and Microlithography and Ionoluminense. Most of these techniques utilise beam currents of 10{sup -15} A down to single ions controlled by beam switching techniques This paper will discuss some of the low beam current techniques mentioned above, and indicate, some of their recent applications at MARC. A new STIM technique will be introduced that can be used to obtain Z-contrast with STIM resolution. 4 refs., 3 figs.

Ion beam assisted synthesis of nano-crystals in glasses (silver and lead chalcogenides)

International Nuclear Information System (INIS)

Espiau de Lamaestre, R.

2005-04-01

This work deals with the interest in ion beams for controlling nano-crystals synthesis in glasses. We show two different ways to reach this aim, insisting on importance of redox phenomena induced by the penetration and implantation of ions in glasses. We first show that we can use the great energy density deposited by the ions to tailor reducing conditions, favorable to metallic nano-crystal precipitation. In particular, we show that microscopic mechanism of radiation induced silver precipitation in glasses are analogous to the ones of classical photography. Ion beams can also be used to overcome supersaturation of elements in a given matrix. In this work, we synthesized lead chalcogenide nano-crystals (PbS, PbSe, PbTe) whose optical properties are interesting for telecommunication applications. We demonstrate the influence of complex chalcogenide chemistry in oxide glasses, and its relationship with the observed loss of growth control when nano-crystals are synthesized by sequential implantation of Pb and S in pure silica. As a consequence of this understanding, we demonstrate a novel and controlled synthesis of PbS nano-crystals, consisting in implanting sulfur into a Pb-containing glass, before annealing. Choice of glass composition provides a better control of precipitation physico-chemistry, whereas the use of implantation allows high nano-crystal volume fractions to be reached. Our study of IR emission properties of these nano-crystals shows a very high excitation cross section, and evidence for a 'dark exciton' emitting level. (author)

Fabrication of nano-scaled polymer-derived SiAlCN ceramic components using focused ion beam

Science.gov (United States)

Tian, Ye; Shao, Gang; Wang, Xingwei; An, Linan

2013-09-01

Fully dense polymer-derived amorphous silicoaluminum carbonitride (SiAlCN) ceramics were synthesized from polysilazane as preceramic precursors followed by a thermal decomposition process. The nanofabrication of amorphous SiAlCN ceramics was implemented with a focused ion beam (FIB). FIB conditions such as the milling rate, the beam current, and the number of passes were considered. It was found that nanopatterns with a feature size of less than 100 nm could be fabricated onto polymer-derived ceramics (PDCs) precisely and quickly. Specific nanostructures of thin walls, nozzle, and gear have been fabricated as demonstrations, indicating that the FIB technique was a promising method to realize nanostructures on PDCs, especially for microelectromechanical system and micro/nano-sensor applications.

Fabrication of nano-scaled polymer-derived SiAlCN ceramic components using focused ion beam

International Nuclear Information System (INIS)

Tian, Ye; Wang, Xingwei; Shao, Gang; An, Linan

2013-01-01

Fully dense polymer-derived amorphous silicoaluminum carbonitride (SiAlCN) ceramics were synthesized from polysilazane as preceramic precursors followed by a thermal decomposition process. The nanofabrication of amorphous SiAlCN ceramics was implemented with a focused ion beam (FIB). FIB conditions such as the milling rate, the beam current, and the number of passes were considered. It was found that nanopatterns with a feature size of less than 100 nm could be fabricated onto polymer-derived ceramics (PDCs) precisely and quickly. Specific nanostructures of thin walls, nozzle, and gear have been fabricated as demonstrations, indicating that the FIB technique was a promising method to realize nanostructures on PDCs, especially for microelectromechanical system and micro/nano-sensor applications. (paper)

Micro/nano analysis of tooth microstructures by Focused Ion Beam (FIB cross-sectioning

Directory of Open Access Journals (Sweden)

Meltem Sezen

2017-04-01

Full Text Available Since dental structures are hard and fragile, cross-sectioning of these materials using ultramicrotomy and other techniques and following micro and nano analysis cause problems. The use of FIB-SEM dual beam platforms is the most convenient solution for investigating the microstructures, site-specifically and in certain geometries. Dual beam platforms allow for imaging at high magnifications and resolutions and simultaneous elemental analysis. In this study, the micro/nano-structural and chemical differences were revealed in dentin and enamel samples. The investigation of dental tissues having different morphologies and chemical components by ion-cross-sectioning is important for the use of FIB-SEM platforms in dentistry in Turkey.

3-dimensional free standing micro-structures by proton beam writing of Su 8-silver nanoParticle polymeric composite

Science.gov (United States)

Igbenehi, H.; Jiguet, S.

2012-09-01

Proton beam lithography a maskless direct-write lithographic technique (well suited for producing 3-Dimensional microstructures in a range of resist and semiconductor materials) is demonstrated as an effective tool in the creation of electrically conductive freestanding micro-structures in an Su 8 + Nano Silver polymer composite. The structures produced show non-ohmic conductivity and fit the percolation theory conduction model of tunneling of separated nanoparticles. Measurements show threshold switching and a change in conductivity of at least 4 orders of magnitude. The predictable range of protons in materials at a given energy is exploited in the creation of high aspect ratio, free standing micro-structures, made from a commercially available SU8 Silver nano-composite (GMC3060 form Gersteltec Inc. a negative tone photo-epoxy with added metallic nano-particles(Silver)) to create films with enhanced electrical properties when exposed and cured. Nano-composite films are directly written on with a finely focused MeV accelerated Proton particle beam. The energy loss of the incident proton beams in the target polymer nano- composite film is concentrated at the end of its range, where damage occurs; changing the chemistry of the nano-composite film via an acid initiated polymerization - creating conduction paths. Changing the energy of the incident beams provide exposed regions with different penetration and damage depth - exploited in the demonstrated cantilever microstructure.

Heteroepitaxy of zinc-blende SiC nano-dots on Si substrate by organometallic ion beam

International Nuclear Information System (INIS)

Matsumoto, T.; Kiuchi, M.; Sugimoto, S.; Goto, S.

2006-01-01

The self-assembled SiC nano-dots were fabricated on Si(111) substrate at low-temperatures using the organometallic ion beam deposition technique. The single precursor of methylsilicenium ions (SiCH 3 + ) with the energy of 100 eV was deposited on Si(111) substrate at 500, 550 and 600 deg. C. The characteristics of the self-assembled SiC nano-dots were analyzed by reflection high-energy electron diffraction (RHEED), Raman spectroscopy and atomic force microscope (AFM). The RHEED patterns showed that the crystal structure of the SiC nano-dots formed on Si(111) substrate was zinc-blende SiC (3C-SiC) and it was heteroepitaxy. The self-assembled SiC nano-dots were like a dome in shape, and their sizes were the length of 200-300 nm and the height of 10-15 nm. Despite the low-temperature of 500 deg. C as SiC crystallization the heteroepitaxial SiC nano-dots were fabricated on Si(111) substrate using the organometallic ion beam

Calorimetric beam-current integrator

International Nuclear Information System (INIS)

Osborne, J.L.

1984-01-01

A single-cup calorimeter for beam-current integration and its associated electronics are described. The design allows beam power up to 120 W and is shown to integrate with an accuracy of 1% over a range of beam energy, current, and power. (orig.)

Frequency Shifts of Micro and Nano Cantilever Beam Resonators Due to Added Masses

KAUST Repository

Bouchaala, Adam M.

2016-03-21

We present analytical and numerical techniques to accurately calculate the shifts in the natural frequencies of electrically actuated micro and nano (carbon nanotubes (CNTs)) cantilever beams implemented as resonant sensors for mass detection of biological entities, particularly Escherichia coli (E. coli) and prostate specific antigen (PSA) cells. The beams are modeled as Euler-Bernoulli beams, including the nonlinear electrostatic forces and the added biological cells, which are modeled as discrete point masses. The frequency shifts due to the added masses of the cells are calculated for the fundamental and higher-order modes of vibrations. Analytical expressions of the natural frequency shifts under a direct current (DC) voltage and an added mass have been developed using perturbation techniques and the Galerkin approximation. Numerical techniques are also used to calculate the frequency shifts and compared with the analytical technique. We found that a hybrid approach that relies on the analytical perturbation expression and the Galerkin procedure for calculating accurately the static behavior presents the most computationally efficient approach. We found that using higher-order modes of vibration of micro-electro-mechanical-system (MEMS) beams or miniaturizing the sizes of the beams to nanoscale leads to significant improved frequency shifts, and thus increased sensitivities. © 2016 by ASME.

NIKHEF: AmPS of electron beam

International Nuclear Information System (INIS)

Anon.

1992-01-01

Now operational at the Dutch National Institute for Nuclear Physics and High Energy Physics (NIKHEF), Amsterdam, is a new tool for studying the electromagnetic properties of nuclei. Called AmPS - Amsterdam pulse stretcher - this ring provides experiments with a smoother, almost continuous supply of electrons

Beam manipulating by metallic nano-slits with variant widths.

Science.gov (United States)

Shi, Haofei; Wang, Changtao; Du, Chunlei; Luo, Xiangang; Dong, Xiaochun; Gao, Hongtao

2005-09-05

A novel method is proposed to manipulate beam by modulating light phase through a metallic film with arrayed nano-slits, which have constant depth but variant widths. The slits transport electro-magnetic energy in the form of surface plasmon polaritons (SPPs) in nanometric waveguides and provide desired phase retardations of beam manipulating with variant phase propagation constant. Numerical simulation of an illustrative lens design example is performed through finite-difference time-domain (FDTD) method and shows agreement with theory analysis result. In addition, extraordinary optical transmission of SPPs through sub-wavelength metallic slits is observed in the simulation and helps to improve elements' energy using factor.

Closed-looped in situ nano processing on a culturing cell using an inverted electron beam lithography system

International Nuclear Information System (INIS)

Hoshino, Takayuki; Mabuchi, Kunihiko

2013-01-01

Highlights: ► An electron beam lithography (EBL) was used as an in situ nano processing for a living cell. ► A synchronized optics was containing an inverted EBL and an optical microscope. ► This system visualized real-time images of the EB-induced nano processing. ► We demonstrated the nano processing for a culturing cell with 200–300 nm resolution. ► Our system would be able to provide high resolution display of virtual environments. -- Abstract: The beam profile of an electron beam (EB) can be focused onto less than a nanometer spot and scanned over a wide field with extremely high speed sweeping. Thus, EB is employed for nano scale lithography in applied physics research studies and in fabrication of semiconductors. We applied a scanning EB as a control system for a living cell membrane which is representative of large scale complex systems containing nanometer size components. First, we designed the opposed co-axial dual optics containing inverted electron beam lithography (I-EBL) system and a fluorescent optical microscope. This system could provide in situ nano processing for a culturing living cell on a 100-nm-thick SiN nanomembrane, which was placed between the I-EBL and the fluorescent optical microscope. Then we demonstrated the EB-induced chemical direct nano processing for a culturing cell with hundreds of nanometer resolution and visualized real-time images of the scanning spot of the EB-induced luminescent emission and chemical processing using a high sensitive camera mounted on the optical microscope. We concluded that our closed-loop in situ nano processing would be able to provide a nanometer resolution display of virtual molecule environments to study functional changes of bio-molecule systems

Study of chemically synthesized ZnO nano particles under a bio template using radioactive ion beam

CERN Multimedia

This is a project proposal to study nano sized semiconductor ZnO system, useful in biology and medicinal purposes, using radioactive ion beam from ISOLDE. Doping of the nano particles with Cu, Cd and Ga ions (in their variable valancy states) are expected to impart changes in the electrical structure and properties in the said system under study. The morphological changes, chemical environment, micro structure, electrical and optical properties of the nano size particles of ZnO system (developed under a bio template of folic acid) after the interaction with radioactive ion beam will be studied. The provision of perturbed angular correlation (PAC) study with respect to the changes in chemical environment, where ever possible will be attempted.

Nano/micro particle beam for ceramic deposition and mechanical etching

International Nuclear Information System (INIS)

Chun, Doo-Man; Kim, Min-Saeng; Kim, Min-Hyeng; Ahn, Sung-Hoon; Yeo, Jun-Cheol; Lee, Caroline Sunyong

2010-01-01

Nano/micro particle beam (NPB) is a newly developed ceramic deposition and mechanical etching process. Additive (deposition) and subtractive (mechanical etching) processes can be realized in one manufacturing process using ceramic nano/micro particles. Nano- or micro-sized powders are sprayed through the supersonic nozzle at room temperature and low vacuum conditions. According to the process conditions, the ceramic powder can be deposited on metal substrates without thermal damage, and mechanical etching can be conducted in the same process with a simple change of process conditions and powders. In the present work, ceramic aluminum oxide (Al 2 O 3 ) thin films were deposited on metal substrates. In addition, the glass substrate was etched using a mask to make small channels. Deposited and mechanically etched surface morphology, coating thickness and channel depth were investigated. The test results showed that the NPB provides a feasible additive and subtractive process using ceramic powders.

A ns-pulsed high-current electron beam source

International Nuclear Information System (INIS)

Guan, Gexin; Li, Youzhi; Pan, Yuli

1988-01-01

The behaviour of a pulse electron beam source which is composed of a gun and pulse system depends on not only the time characteristics of the gun and the pulser, but also their combination. This point become apparent if effects of the electron tansit-time between electrodes are studied. A ferrite transmission line (FTL) pulser is used as a grid driver in this source. It has advantages of providing fast risetime, large peak power output and good loading characteristics. It is these advantages of the pulser that compensates the absence of some technological conditions of manufacturing gun and makes the source better. Our testing showed that the cooperation of both the gun and the pulser produced peak currents in the range of 1 to 9 amps with widths of 2 to 2.5 ns (FWHM) at cathode-to-anode potential of 60 to 82 kv, while the grid drives are about in the range of 1 to 3 kv. In addition, the results of the testing instructed that effects of electron transit-time cannot be ignored when the pulses with widths of several nanoseconds are used as a grid drive. Based on the results, electron transit-time effects on the design of the gun and the beam performances are briefly descussed in this paper. (author)

Selective Adsorption of Nano-bio materials and nanostructure fabrication on Molecular Resists Modified by proton beam irradiation

International Nuclear Information System (INIS)

Lee, H. W.; Kim, H. S.; Kim, S. M.

2008-04-01

The purpose of this research is the fabrication of nanostructures on silicon substrate using proton beam and selectively adsorption of bio-nano materials on the patterned substrate. Recently, the miniaturization of the integrated devices with fine functional structures was intensively investigated, based on combination of nanotechnology (NT), biotechnology (BT) and information technology (IT). Because of the inherent limitation in optical lithography, large variety of novel patterning technologies were evolved to construct nano-structures onto a substrate. Atomic force microscope-based nanolithography has readily formed sub-50 nm patterns by the local modification of a substrate using a probe with a curvature of 10 nm. The surface property was regarded as one of the most important factors for AFM-based nanolithography as well as for other novel nanolithographies. The molecular thin films such as a self-assembled monolayer or a polymer resist layer have been used as an alternative to modifying the surface property. Although proton or ion beam irradiation has been used as an efficient tool to modify the physical, chemical and electrical properties of a surface, the nano-patterning on the substrate or the molecular film modified with the beam irradiation has hardly been studied at both home and abroad. The selective adsorption of nano-bio materials such as carbon nanotubes and proteins on the patterns would contribute to developing the integrated devices. The polystyrene nanoparticles (400 nm) were arrayed on al silicon surface using nanosphere lithography and the various nanopatterns were fabricated by proton beam irradiation on the polystyrene nanoparticles arrayed silicon surface. We obtained the two different nanopatterns such as polymer nanoring patterns and silicon oxide patterns on the same silicon substrate. The polymer nanoring patterns formed by the crosslinkage of polystyrene when proton beam was irradiated at the triangular void spaces that are enclosed by

Toroidal ripple transport of beam ions in the mega-ampère spherical tokamak

International Nuclear Information System (INIS)

McClements, K. G.; Hole, M. J.

2012-01-01

The transport of injected beam ions due to toroidal magnetic field ripple in the mega-ampère spherical tokamak (MAST) is quantified using a full orbit particle tracking code, with collisional slowing-down and pitch-angle scattering by electrons and bulk ions taken into account. It is shown that the level of ripple losses is generally rather low, although it depends sensitively on the major radius of the outer midplane plasma edge; for typical values of this parameter in MAST plasmas, the reduction in beam heating power due specifically to ripple transport is less than 1%, and the ripple contribution to beam ion diffusivity is of the order of 0.1 m 2 s –1 or less. It is concluded that ripple effects make only a small contribution to anomalous transport rates that have been invoked to account for measured neutron rates and plasma stored energies in some MAST discharges. Delayed (non-prompt) losses are shown to occur close to the outer midplane, suggesting that banana-drift diffusion is the most likely cause of the ripple-induced losses.

A beam position monitor for low current dc beams

International Nuclear Information System (INIS)

Adderley, P.; Barry, W.; Heefner, J.; Kloeppel, P.; Rossmanith, R.; Wise, M.; Jachim, S.

1989-01-01

The 4 GeV recirculating linac, CEBAF, if presently under construction and will produce a CW beam with average current between.1 and 200 μA. In order to measure beam position, the beam current will be amplitude modulated at a frequency of 10 MHz. The modulation is detected by an inductive loop type monitor with electronics sensitive only to the modulation frequency. The first test with beam from the CEBAF injector indicate that beam position can be measured with an accuracy of .1 mm at a modulated beam current of 1 μA. 1 ref., 6 figs., 1 tab

Self-aligned periodic Ni nano dots embedded in nano-oxide layer

International Nuclear Information System (INIS)

Doi, M.; Izumi, M.; Kawasaki, S.; Miyake, K.; Sahashi, M.

2007-01-01

The Ni nano constriction dots embedded in the Ta-nano-oxide layer (NOL) was prepared by the ion beam sputtering (IBS) method. After the various conditions of the oxidations, the structural analyses of the NOL were performed by RHEED, AES and in situ STM/AFM observations. From the current image of the conductive AFM for NOL, the periodically aligned metallic dots with the size around 5-10 nm were successfully observed. The mechanism of the formation of the self-organized aligned Ni nano constriction dots is discussed from the standpoint of the grain size, the crystal orientation, the preferred oxidation of Ta at the diffused interface

Nonlinear primary resonance of micro/nano-beams made of nanoporous biomaterials incorporating nonlocality and strain gradient size dependency

Science.gov (United States)

Sahmani, S.; Aghdam, M. M.

2018-03-01

A wide range of biological applications such as drug delivery, biosensors and hemodialysis can be provided by nanoporous biomaterials due to their uniform pore size as well as considerable pore density. In the current study, the size dependency in the nonlinear primary resonance of micro/nano-beams made of nanoporous biomaterials is anticipated. To accomplish this end, a refined truncated cube is introduced to model the lattice structure of nanoporous biomaterial. Accordingly, analytical expressions for the mechanical properties of material are derived as functions of pore size. After that, based upon a nonlocal strain gradient beam model, the size-dependent nonlinear Duffing type equation of motion is constructed. The Galerkin technique together with the multiple time-scales method is employed to obtain the nonlocal strain gradient frequency-response and amplitude-response related to the nonlinear primary resonance of a micro/nano-beam made of the nanoporous biomaterial with different pore sizes. It is indicated that the nonlocality causes to decrease the response amplitudes associated with the both bifurcation points of the jump phenomenon, while the strain gradient size dependency causes to increase them. Also, it is found that increasing the pore size leads to enhance the nonlinearity, so the maximum deflection of response occurs at higher excitation frequency.

High current beam transport with multiple beam arrays

International Nuclear Information System (INIS)

Kim, C.H.

1985-05-01

Highlights of recent experimental and theoretical research progress on the high current beam transport of single and multiple beams by the Heavy Ion Fusion Accelerator Research (HIFAR) group at the Lawrence Berkeley Laboratory (LBL) are presented. In the single beam transport experiment (SBTE), stability boundaries and the emittance growth of a space charge dominated beam in a long quadrupole transport channel were measured and compared with theory and computer simulations. Also, a multiple beam ion induction linac (MBE-4) is being constructed at LBL which will permit study of multiple beam transport arrays, and acceleration and bunch length compression of individually focused beamlets. Various design considerations of MBE-4 regarding scaling laws, nonlinear effects, misalignments, and transverse and longitudinal space charge effects are summarized. Some aspects of longitudinal beam dynamics including schemes to generate the accelerating voltage waveforms and to amplify beam current are also discussed

Effects of electron beam irradiation on inorganic exchanger AMP

International Nuclear Information System (INIS)

Rao, K.L.N.; Mathew, C.; Deshpande, R.S.; Jadhav, A.V.; Pande, B.M.; Shukla, J.P.

1996-01-01

The heteropolyacid salt inorganic exchanger ammonium molybdophosphate (AMP) was subjected to an electron dose upto 2 MGy to assess any possible radiation damage. The breakthrough and total exchange capacity of AMP for Cs + from simulated fission product solutions were determined for both control and irradiated samples. The scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDX) were deployed to examine any marked microscopic changes taking place in this exchanger. (author). 3 refs., 3 figs

Polychromatic X-ray Micro- and Nano-Beam Science and Instrumentation

Science.gov (United States)

Ice, G. E.; Larson, B. C.; Liu, W.; Barabash, R. I.; Specht, E. D.; Pang, J. W. L.; Budai, J. D.; Tischler, J. Z.; Khounsary, A.; Liu, C.; Macrander, A. T.; Assoufid, L.

2007-01-01

Polychromatic x-ray micro- and nano-beam diffraction is an emerging nondestructive tool for the study of local crystalline structure and defect distributions. Both long-standing fundamental materials science issues, and technologically important questions about specific materials systems can be uniquely addressed. Spatial resolution is determined by the beam size at the sample and by a knife-edge technique called differential aperture microscopy that decodes the origin of scattering from along the penetrating x-ray beam. First-generation instrumentation on station 34-ID-E at the Advanced Photon Source (APS) allows for nondestructive automated recovery of the three-dimensional (3D) local crystal phase and orientation. Also recovered are the local elastic-strain and the dislocation tensor distributions. New instrumentation now under development will further extend the applications of polychromatic microdiffraction and will revolutionize materials characterization.

Polychromatic X-ray Micro- and Nano-Beam Science and Instrumentation

International Nuclear Information System (INIS)

Ice, G.E.; Larson, Ben C.; Liu, Wenjun; Barabash, Rozaliya; Specht, Eliot D; Pang, Judy; Budai, John D.; Tischler, Jonathan Zachary; Khounsary, Ali; Liu, Chian; Macrander, Albert T.; Assoufid, Lahsen

2007-01-01

Polychromatic x-ray micro- and nano-beam diffraction is an emerging nondestructive tool for the study of local crystalline structure and defect distributions. Both long-standing fundamental materials science issues, and technologically important questions about specific materials systems can be uniquely addressed. Spatial resolution is determined by the beam size at the sample and by a knife-edge technique called differential aperture microscopy that decodes the origin of scattering from along the penetrating x-ray beam. First-generation instrumentation on station 34-ID-E at the Advanced Photon Source (APS) allows for nondestructive automated recovery of the three-dimensional (3D) local crystal phase and orientation. Also recovered are the local elastic-strain and the dislocation tensor distributions. New instrumentation now under development will further extend the applications of polychromatic microdiffraction and will revolutionize materials characterization

LANSCE Beam Current Limiter (XL)

International Nuclear Information System (INIS)

Gallegos, F.R.; Hall, M.J.

1997-01-01

The Radiation Security System (RSS) at the Los Alamos Neutron Science Center (LANSCE) is an engineered safety system that provides personnel protection from prompt radiation due to accelerated proton beams. The Beam Current Limiter (XL), as an active component of the RSS, limits the maximum average current in a beamline, thus the current available for a beam spill accident. Exceeding the pre-set limit initiates action by the RSS to mitigate the hazard (insertion of beam stoppers in the low energy beam transport). The beam limiter is an electrically isolated, toroidal transformer and associated electronics. The device was designed to continuously monitor beamline currents independent of any external timing. Fail-safe operation was a prime consideration in its development. Fail-safe operation is defined as functioning as intended (due to redundant circuitry), functioning with a more sensitive fault threshold, or generating a fault condition. This report describes the design philosophy, hardware, implementation, operation, and limitations of the device

Current neutralization of nanosecond risetime, high-current electron beam

International Nuclear Information System (INIS)

Lidestri, J.P.; Spence, P.W.; Bailey, V.L.; Putnam, S.D.; Fockler, J.; Eichenberger, C.; Champney, P.D.

1991-01-01

This paper reports that the authors have recently investigated methods to achieve current neutralization in fast risetime (<3 ns) electron beams propagating in low-pressure gas. For this investigation, they injected a 3-MV, 30-kA intense beam into a drift cell containing gas pressures from 0.10 to 20 torr. By using a fast net current monitor (100-ps risetime), it was possible to observe beam front gas breakdown phenomena and to optimize the drift cell gas pressure to achieve maximum current neutralization. Experimental observations have shown that by increasing the drift gas pressure (P ∼ 12.5 torr) to decrease the mean time between secondary electron/gas collisions, the beam can propagate with 90% current neutralization for the full beam pulsewidth (16 ns)

Current safety practices in nano-research laboratories in China.

Science.gov (United States)

Zhang, Can; Zhang, Jing; Wang, Guoyu

2014-06-01

China has become a key player in the global nanotechnology field, however, no surveys have specifically examined safety practices in the Chinese nano-laboratories in depth. This study reports results of a survey of 300 professionals who work in research laboratories that handle nanomaterials in China. We recruited participants at three major nano-research laboratories (which carry out research in diverse fields such as chemistry, material science, and biology) and the nano-chemistry session of the national meeting of the Chinese Chemical Society. Results show that almost all nano-research laboratories surveyed had general safety regulations, whereas less than one third of respondents reported having nanospecific safety rules. General safety measures were in place in most surveyed nano-research laboratories, while nanospecific protective measures existed or were implemented less frequently. Several factors reported from the scientific literature including nanotoxicology knowledge gaps, technical limitations on estimating nano-exposure, and the lack of nano-occupational safety legislation may contribute to the current state of affairs. With these factors in mind and embracing the precautionary principle, we suggest strengthening or providing nanosafety training (including raising risk awareness) and establishing nanosafety guidelines in China, to better protect personnel in the nano-workplace.

80 kV electrostatic wire septum for AmPS

International Nuclear Information System (INIS)

Linden, A. van der; Bijleveld, J.H.M.; Rookhuizen, H.B.; Bruinsma, P.J.T.; Heine, E.; Lassing, P.; Prins, E.

1992-01-01

The Amsterdam Pulse Stretcher (AmPS) ring aims at a 100% duty cycle operation by means of slow extraction of injected electron beam pulses of 2.1 μs. In the extraction process of the AmPS, the extracted beam is intercepted from the circulating beam by the 1 m long electrostatic wire septum. For a bending angle of 4.4 mrad the maximum anode voltage is 80 kV. Care has been given to the electric field distribution at the entrance and exit of the septum and to the insulators, required to support the anode. Prototype tests have been successful up to an anode voltage of 120 kV. (R.P.) 9 refs.; 5 figs

Improvement of mechanical and thermal properties of high energy electron beam irradiated HDPE/hydroxyapatite nano-composite

Science.gov (United States)

Mohammadi, M.; Ziaie, F.; Majdabadi, A.; Akhavan, A.; Shafaei, M.

2017-01-01

In this research work, the nano-composites of high density polyethylene/hydroxyapatite samples were manufactured via two methods: In the first method, the granules of high density polyethylene and nano-structure hydroxyapatite were processed in an internal mixer to prepare the nano-composite samples with a different weight percentage of the reinforcement phase. As for the second one, high density polyethylene was prepared in nano-powder form in boiling xylene. During this procedure, the hydroxyapatite nano-powder was added with different weight percentages to the solvent to obtain the nano-composite. In both of the procedures, the used hydroxyapatite nano-powder was synthesized via hydrolysis methods. The samples were irradiated under 10 MeV electron beam in 70-200 kGy of doses. Mechanical, thermal and morphological properties of the samples were investigated and compared. The results demonstrate that the nano-composites which we have prepared using nano-polyethylene, show better mechanical and thermal properties than the composites prepared from normal polyethylene granules, due to the better dispersion of nano-particles in the polymer matrix.

Buckling analysis of micro- and nano-rods/tubes based on nonlocal Timoshenko beam theory

International Nuclear Information System (INIS)

Wang, C M; Zhang, Y Y; Ramesh, Sai Sudha; Kitipornchai, S

2006-01-01

This paper is concerned with the elastic buckling analysis of micro- and nano-rods/tubes based on Eringen's nonlocal elasticity theory and the Timoshenko beam theory. In the former theory, the small scale effect is taken into consideration while the effect of transverse shear deformation is accounted for in the latter theory. The governing equations and the boundary conditions are derived using the principle of virtual work. Explicit expressions for the critical buckling loads are derived for axially loaded rods/tubes with various end conditions. These expressions account for a better representation of the buckling behaviour of micro- and nano-rods/tubes where small scale effect and transverse shear deformation effect are significant. By comparing it with the classical beam theories, the sensitivity of the small scale effect on the buckling loads may be observed

Quantitative strain analysis for advanced CMOS technology by Nano Beam Diffraction

KAUST Repository

Wang, Qingxiao

2010-07-01

Nano Beam Diffraction has been used to analyze the local strain distribution in MOS transistors. The influence of wafer process on the channel strain has been systematically analyzed in this paper. The source/drain implantation can cause a little strain loss but the silicidation step is the key process in which dramatic strain loss has been found. © 2010 IEEE.

Quantitative strain analysis for advanced CMOS technology by Nano Beam Diffraction

KAUST Repository

Wang, Qingxiao; Zhu, Jinmin; Du, Anyan; Liu, Jinping; Hua, YouNan

2010-01-01

Nano Beam Diffraction has been used to analyze the local strain distribution in MOS transistors. The influence of wafer process on the channel strain has been systematically analyzed in this paper. The source/drain implantation can cause a little strain loss but the silicidation step is the key process in which dramatic strain loss has been found. © 2010 IEEE.

Squid based beam current meter

International Nuclear Information System (INIS)

Kuchnir, M.

1983-01-01

A SQUID based beam current meter has the capability of measuring the current of a beam with as little as 30 x 155 antiprotons (with a signal to noise ratio of 2). If low noise dc current is used to cancel most of the beam or an up-down counter is used to count auto-resets this sensitivity will be available at any time in the acumulation process. This current meter will therefore be a unique diagnostic tool for optimizing the performance of several Tev I components. Besides requiring liquid helium it seems that its only drawback is not to follow with the above sensitivity a sudden beam change larger than 16 μA, something that could be done using a second one in a less sensitive configuration

Crane RF accelerator for high current radiation damage studies

International Nuclear Information System (INIS)

Whitham, K.; Anamkath, H.; Evans, K.; Lyons, S.; Palmer, D.; Miller, R.; Treas, P.; Zante, T.

1992-01-01

An electron accelerator was designed and built for the Naval Weapons Support Center for transient radiation effects on electronics experiments and testing. The Crane L Band RF Electron Linac was designed to provide high currents over a wide range of pulse widths and energies. The energy extends to 60 MeV and pulse widths vary from a few ns to 10 μsec. Beam currents range from 20 amps in the short pulse case to 1.5 amps in the long pulse case. This paper describes the linac, its architecture, the e-gun and pulser, waveguides, klystrons and modulator, vacuum system, beam transport, and control systems. fig., tab

Tutorial on beam current monitoring

International Nuclear Information System (INIS)

Webber, Robert C.

2000-01-01

This paper is a tutorial level review covering a wide range of aspects related to charged particle beam current measurement. The tutorial begins with a look at the characteristics of the beam as a signal source, the associated electromagnetic fields, the influence of the typical accelerator environment on those fields, and the usual means of modifying and controlling that environment to facilitate beam current measurement. Short descriptions of three quite different types of current monitors are presented and a quantitative review of the classical transformer circuit is given. Recognizing that environmental noise pick-up may present a large source of error in quantitative measurements, signal handling considerations are given considerable attention using real-life examples. An example of a successful transport line beam current monitor implementation is presented and the tutorial concludes with a few comments about signal processing and current monitor calibration issues

Ion Beam Etching: Replication of Micro Nano-structured 3D Stencil Masks

International Nuclear Information System (INIS)

Weber, Patrick; Guibert, Edouard; Mikhailov, Serguei; Bruegger, Juergen; Villanueva, Guillermo

2009-01-01

Ion beam LIGA allows the etching of 3D nano-structures by direct writing with a nano-sized beam. However, this is a relatively time consuming process. We propose here another approach for etching structures on large surfaces and faster, compared to the direct writing process. This approach consists of replicating 3D structured masks, by scanning an unfocused ion beam. A polymer substrate is placed behind the mask, as in UV photolithography. But the main advantage is that the 3D structure of the mask can be replicated into the polymer. For that purpose, the masks (developped at LMIS1, EPFL) are made of a silicon nitride membrane 100 nm thick, on which 3D gold structures up to 200 nm thick, are deposited. The 3D Au structures are made with the nanostencil method, based on successive gold deposition. The IMA institute, from HE-Arc, owns a High Voltage Engineering 1.7 MV Tandetron with both solid and gaseous negative ion sources, able to generate ions from almost every chemical element in a broad range of energies comprised between 400 keV and 6.8 MeV. The beam composition and energy are chosen in such a way, that ions lose a significant fraction of their energy when passing through the thickest regions of the mask. Ions passing through thinner regions of the mask loose a smaller fraction of their energy and etch the polymer with larger thicknesses, allowing a replication of the mask into the polymer. For our trials, we have used a carbon beam with an energy of 500 keV. The beam was focussed to a diameter of 5 mm with solid slits, in order to avoid border effects and thus ensure a homogeneous dose distribution on the beam diameter. The feasibility of this technique has been demonstrated, allowing industrial applications for micro-mould fabrication, micro-fluidics and micro-optics.

Static and free vibration analysis of carbon nano wires based on Timoshenko beam theory using differential quadrature method

Directory of Open Access Journals (Sweden)

Maziar Janghorban

Full Text Available Static and free vibration analysis of carbon nano wires with rectangular cross section based on Timoshenko beam theory is studied in this research. Differential quadrature method (DQM is employed to solve the governing equations. From the knowledge of author, it is the first time that free vibration of nano wires is investigated. It is also the first time that differential quadrature method is used for bending analysis of nano wires.

Microwave assisted coating of bioactive amorphous magnesium phosphate (AMP) on polyetheretherketone (PEEK).

Science.gov (United States)

Ren, Yufu; Sikder, Prabaha; Lin, Boren; Bhaduri, Sarit B

2018-04-01

Polyetheretherketone (PEEK) with great thermal and chemical stability, desirable mechanical properties and promising biocompatibility is being widely used as orthopedic and dental implant materials. However, the bioinert surface of PEEK can hinder direct osseointegration between the host tissue and PEEK based implants. The important signatures of this paper are as follows. First, we report for the formation of osseointegrable amorphous magnesium phosphate (AMP) coating on PEEK surface using microwave energy. Second, coatings consist of nano-sized AMP particles with a stacked thickness of 800nm. Third, coatings enhance bioactivity in-vitro and induce significantly high amount of bone-like apatite coating, when soaked in simulated body fluid (SBF). Fourth, the as-deposited AMP coatings present no cytotoxicity effects and are beneficial for cell adhesion at early stage. Finally, the high levels of expression of osteocalcin (OCN) in cells cultured on AMP coated PEEK samples indicate that AMP coatings can promote new bone formation and hence osseointegration. Copyright © 2017 Elsevier B.V. All rights reserved.

Behaviour of Nano Silica in Tension Zone of High Performance Concrete Beams

Science.gov (United States)

Jaishankar, P.; Vivek, D.

2017-07-01

High performance concrete (HPC) is similar to High strength concrete (HSC).It is because of lowering of water to cement ratio, which is needed to attain high strength and generally improves other properties. This concrete contains one or more cementitious materials such as fly ash, Silica fume or ground granulated blast furnace slag and usually a super plasticizer. The term ‘high performance’ is somewhat different because the essential feature of this concrete is that it’s ingredients and proportions are specifically chosen so as to have particularly appropriate properties for the expected use of the structure such as high strength and low permeability. Usage of nano scale properties such as Nano SiO2 can result in dramatically improved properties from conventional grain size materials of same chemical composition. This project is more interested in evaluate the behaviour of nano silica in concrete for 5%, 10%, and 15% volume fraction of cement. Flexural test for beams were conducted with two point loads, at different percentage as mentioned above. From results interpolated, Nano silica with higher order replacement gives optimized results compared to control specimens.

Sensitive beam current measurement for FAIR

Energy Technology Data Exchange (ETDEWEB)

Schwickert, Marcus; Kurian, Febin; Reeg, Hansjoerg [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Seidel, Paul; Neubert, Ralf [Friedrich-Schiller-Universitaet Jena (Germany); Geithner, Rene; Vodel, Wolfgang [Helmholtz-Institut Jena (Germany)

2012-07-01

Presently FAIR, the Facility for Antiproton and Ion Research, entered the final planning phase at GSI. The new accelerator facility requires precise devices for beam current measurements due to the large dynamics in beam intensities for the various synchrotrons, transport lines and storage rings. We report on the actual developments of beam diagnostic devices for the measurement of beam intensities ranging from 5 x 10{sup 11} uranium ions down to the detection of less than 10{sup 4} antiprotons. This contribution gives an overview of the planned instruments with a focus on non-intercepting beam current transformers, and summarizes the on-going development of a cryogenic current comparator.

High current density ion beam measurement techniques

International Nuclear Information System (INIS)

Ko, W.C.; Sawatzky, E.

1976-01-01

High ion beam current measurements are difficult due to the presence of the secondary particles and beam neutralization. For long Faraday cages, true current can be obtained only by negative bias on the target and by summing the cage wall and target currents; otherwise, the beam will be greatly distorted. For short Faraday cages, a combination of small magnetic field and the negative target bias results in correct beam current. Either component alone does not give true current

High bandwidth beam current monitor

International Nuclear Information System (INIS)

Baltrusaitis, R.M.; Ekdahl, C.A.; Cooper, R.G.; Peterson, E.; Warn, C.E.

1993-01-01

A stripline directional coupler beam current monitor capable of measuring the time structure of a 30-ps electron beam bunch has been developed. The time response performance of the monitor compares very well with Cherenkov light produced in quartz by the electron beam. The four-pickup monitor is now used on a routine basis for measuring the beam duration, tuning for optimized beam bunching, and centering the bunch in the beam pipe

Digitally compensated beam current transformer

International Nuclear Information System (INIS)

Kesselman, Martin

2005-01-01

The Spallation Neutron Source (SNS) is being built by a collaboration of six laboratories. Beam current monitors (BCMs) will be used to record the current of H-minus and H-plus beams ranging from 15 mA (tune-up in the Front End and Linac) to over 60A fully accumulated in the Ring and dumped to the load as a single pulse in the Ring to Beam Target (RTBT). The time structure of these beams ranges from 645 ns 'mini' bunches at the 1.05 MHz ring revolution rate, to an overall 1 ms long macro-pulse. The requirements for the BCMs will depend upon their location within the system. The need to measure individual mini-pulses, examine the characteristics of the chopper edge, as well as the longer average current pulse of the macropulse, or long duration pulses during Linac tuning place wide requirements upon the response of current transformers. To obtain the desired accuracy and resolution, current transformers must have <1 ns rise time and droops of 0.1%/ms. This places a significant design burden on the current transformer; such a design is almost impossible to achieve. Extremely large expensive cores are needed to meet the low droop, while leakage inductance increases with size, thereby reducing the achievable rise time. In this paper, I discuss a digital compensation approach [M. Kesselman, Spallation neutron source beam current monitor electronics, PAC2001 June 18-22, 2001, Chicago, IL.] that extends the lower cut-off frequency of the current transformer, optimized for high frequency response, so that it can be used in this application with improvements in droop of the order of 1000:1. Transformer saturation (current-time product) is a separate issue and the transformer must be designed to handle the current-time product of the signal to assure it does not saturate

Safeguards Technology Factsheet - Unattended Dual Current Monitor (UDCM)

International Nuclear Information System (INIS)

Newell, Matthew R.

2016-01-01

The UDCM is a low-current measurement device designed to record sub-nano-amp to micro-amp currents from radiation detectors. The UDCM is a two-channel device that incorporates a Commercial-Off-The-Shelf (COTS) processor enabling both serial over USB as well as Ethernet communications. The instrument includes microSD and USB flash memory for data storage as well as a programmable High Voltage (HV) power supply for detector bias. The UDCM is packaged in the same enclosure, employs the same processor and has a similar user interface as the UMSR. A serial over USB communication line to the UDCM allows the use of existing versions of MIC software, while the Ethernet port is compatible with the new IAEA RAINSTORM communication protocol.

Online diagnoses of high current-density beams

International Nuclear Information System (INIS)

Gilpatrick, J.D.

1994-01-01

Los Alamos National Laboratory has proposed several CW-proton-beam facilities for production of tritium or transmutation of nuclear waste with beam-current densities greater than 5 mA/mm 2 . The primary beam-diagnostics-instrumentation requirement for these facilities is provision of sufficient beam information to understand and minimize beam-loss. To accomplish this task, the beam-diagnostics instrumentation must measure beam parameters such as the centroids and profiles, total integrated current, and particle loss. Noninterceptive techniques must be used for diagnosis of high-intensity CW beam at low energies due to the large quantity of power deposited in an interceptive diagnostic device by the beam. Transverse and longitudinal centroid measurements have been developed for bunched beams by measuring and processing image currents on the accelerator walls. Transverse beam-profile measurement-techniques have also been developed using the interaction of the particle beam with the background gases near the beam region. This paper will discuss these noninterceptive diagnostic Techniques

A first-principles study on the adsorption behavior of amphetamine on pristine, P- and Al-doped B12N12 nano-cages

Science.gov (United States)

Bahrami, Aidin; Seidi, Shahram; Baheri, Tahmineh; Aghamohammadi, Mohammad

2013-12-01

The first-principles computations using density functional theory (DFT) calculations at the M062X/6-311++G** level have been applied to scrutinize the adsorption behavior of amphetamine (AMP) molecule on the external surface of pristine, P- and Al-doped B12N12 nano-cages. In order to gain insight into the binding features of pristine and doped B12N12 complexes as adsorbent with AMP, the structural and electronic parameters as well as the Atoms in Molecules (AIM) properties were examined. The results showed that AMP prefers to adsorb via its nitrogen atom on the Lewis acid sites of B and Al atoms of the nano-cages. On the basis of calculated density of states, the interaction of AMP with the external wall of B12N12 leads to the remarkable differences in their conductivities. Presence of polar solvent increases the AMP adsorption on the nano-cage. In addition, AIM based analyses indicated an electrostatic nature for N-B interaction in Amph-B12N12 and partial covalent for N-Al in AMP-B11AlN12. Based on calculated results, the B12N12 and B11AlN12 nano-cages are expected to be a potential efficient adsorbent as well as sensors for adsorption of AMP in environmental systems.

Controlled fabrication of nano-scale double barrier magnetic tunnel junctions using focused ion beam milling method

International Nuclear Information System (INIS)

Wei, H.X.; Wang, T.X.; Zeng, Z.M.; Zhang, X.Q.; Zhao, J.; Han, X.F.

2006-01-01

The controlled fabrication method for nano-scale double barrier magnetic tunnel junctions (DBMTJs) with the layer structure of Ta(5)/Cu(10)/Ni 79 Fe 21 (5)/Ir 22 Mn 78 (12)/Co 6 Fe 2 B 2 (4)/Al(1) -oxide/Co 6 Fe 2 B 2 (6)/Al (1)-oxide/Co 6 Fe 2 B 2 (4)/Ir 22 Mn 78 (12)/Ni 79 Fe 21 (5)/Ta(5) (thickness unit: nm) was used. This method involved depositing thin multi-layer stacks by sputtering system, and depositing a Pt nano-pillar using a focused ion beam which acted both as a top contact and as an etching mask. The advantages of this process over the traditional process using e-beam and optical lithography in that it involve only few processing steps, e.g. it does not involve any lift-off steps. In order to evaluate the nanofabrication techniques, the DBMTJs with the dimensions of 200 nmx400 nm, 200 nmx200 nm nano-scale were prepared and their R-H, I-V characteristics were measured.

Precision intercomparison of beam current monitors at CEBAF

International Nuclear Information System (INIS)

Kazimi, R.; Dunham, B.; Krafft, G.A.; Legg, R.; Liang, C.; Sinclair, C.; Mamosser, J.

1995-01-01

The CEBAF accelerator delivers a CW electron beam at fundamental 1497 MHz, with average beam current up to 200 μA. Accurate, stable nonintercepting beam current monitors are required for: setup/control, monitoring of beam current and beam losses for machine protection and personnel safety, and providing beam current information to experimental users. Fundamental frequency stainless steel RF cavities have been chosen for these beam current monitors. This paper reports on precision intercomparison between two such RF cavities, an Unser monitor, and two Faraday cups, all located in the injector area. At the low beam energy in the injector, it is straightforward to verify the high efficiency of the Faraday cups, and the Unser monitor included a wire through it to permit an absolute calibration. The cavity intensity monitors have proven capable of stable, high precision monitoring of the beam current

Nano-fabrication of diffractive optics for soft X-ray and atom beam focusing

International Nuclear Information System (INIS)

Rehbein, S.

2002-01-01

Nano-structuring processes are described for manufacturing diffractive optics for the condenser-monochromator set-up of the transmission X-ray microscope (TXM) and for the scanning transmission X-ray microscope (STXM) at the BESSY II electron storage ring in Berlin. Furthermore, a process for manufacturing free-standing nickel zone plates for helium atom beam focusing experiments is presented. (author)

rf beam-current, -phase, and -position monitors

International Nuclear Information System (INIS)

Young, L.

1984-01-01

A prototype rf beam monitor has been tested on the Racetrack Microtron's (RTM) 100 kV injector beam line at the National Bureau of Standards (NBS). This beam monitor is capable of measuring the current, the relative phase, and the position of the beam. The beam is bunched at 2380 MHz for acceleration by the linac in the injector beam line. This train of beam bunches passing through the beam monitor cavities excites the cavities at this resonance frequency of 2380 MHz. Probes in the cavities couple some of the beam-excited rf power out of the cavities. This rf power can be amplified if necessary and then analyzed by a double balanced mixer (DBM). The DBM can also be used as a phase detector. The effective shunt impedance of the cavities was measured with the CW beam. For the position monitor cavity, the shunt impedance is proportional to the displacement from the axis. The measured response of the prototype rf beam current monitor setup is a linear function of beam current. Response of the rf beam-position monitor is also shown

Neutral-beam current drive in tokamaks

International Nuclear Information System (INIS)

Devoto, R.S.

1986-01-01

The theory of neutral-beam current drive in tokamaks is reviewed. Experiments are discussed where neutral beams have been used to drive current directly and also indirectly through neoclassical effects. Application of the theory to an experimental test reactor is described. It is shown that neutral beams formed from negative ions accelerated to 500 to 700 keV are needed for this device

Neutral-beam current drive in tokamaks

International Nuclear Information System (INIS)

Devoto, R.S.

1987-01-01

The theory of neutral-beam current drive in tokamaks is reviewed. Experiments are discussed where neutral beams have been used to drive current directly and also indirectly through neoclassical effects. Application of the theory to an experimental test reactor is described. It is shown that neutral beams formed from negative ions accelerated to 500-700 keV are needed for this device

SNS project-wide beam current monitors

International Nuclear Information System (INIS)

Kesselman, M.; Witkover, R.; Doolittle, L.; Power, J.

2000-01-01

A consortium of national laboratories is constructing the Spallation Neutron Source [1] (SNS) to be installed at Oak Ridge National Laboratory. There are signal similarities that exist in the beam diagnostic instrumentation that could permit common designs. This paper will focus on the beam current monitoring requirements, and the methods under consideration to measure beam current in various locations throughout the SNS facility

Analytical study of the frequency shifts of micro and nano clamped–clamped beam resonators due to an added mass

KAUST Repository

Bouchaala, Adam M.

2016-03-18

We present analytical formulations to calculate the induced resonance frequency shifts of electrically actuated clamped–clamped micro and nano (Carbon nanotube) beams due to an added mass. Based on the Euler–Bernoulli beam theory, we investigate the linear dynamic responses of the beams added masses, which are modeled as discrete point masses. Analytical expressions based on perturbation techniques and a one-mode Galerkin approximation are developed to calculate accurately the frequency shifts under a DC voltage as a function of the added mass and position. The analytical results are compared to numerical solution of the eigenvalue problem. Results are shown for the fundamental as well as the higher-order modes of the beams. The results indicate a significant increase in the frequency shift, and hence the sensitivity of detection, when scaling down to nano scale and using higher-order modes. © 2016 Springer Science+Business Media Dordrecht

Design and construction of UVSOR-BL4A2 beam line for nano-structure processing

CERN Document Server

Takezoe, N; Tanaka, T; Kurosawa, K; Nonogaki, Y; Noda, H; Mekaru, H; Urisu, T

2001-01-01

We have designed and constructed a new beam line BL4A2 at UVSOR mainly for nano-structure fabrication based on synchrotron radiation stimulated surface photochemical reactions. In order to obtain high-photon flux, we use white ray beam focused with only one mirror. The beam line is connected with ultra-high vacuum scanning tunneling microscope for in-situ atomic scale observations, low energy electron diffraction and Auger electron spectroscope for surface crystal structure characterization, and photo-stimulated surface reaction chamber. In order to monitor the optical properties with atomic scale, a near field optical microscope is planned to be installed.

Design and construction of UVSOR-BL4A2 beam line for nano-structure processing

International Nuclear Information System (INIS)

Takezoe, N.; Yanagida, H.; Tanaka, T.; Kurosawa, K.; Nonogaki, Y.; Noda, H.; Mekaru, H.; Urisu, T.

2001-01-01

We have designed and constructed a new beam line BL4A2 at UVSOR mainly for nano-structure fabrication based on synchrotron radiation stimulated surface photochemical reactions. In order to obtain high-photon flux, we use white ray beam focused with only one mirror. The beam line is connected with ultra-high vacuum scanning tunneling microscope for in-situ atomic scale observations, low energy electron diffraction and Auger electron spectroscope for surface crystal structure characterization, and photo-stimulated surface reaction chamber. In order to monitor the optical properties with atomic scale, a near field optical microscope is planned to be installed

Dynamics of current induced nano-skyrmions

Energy Technology Data Exchange (ETDEWEB)

Natarajan, Kanimozhi; Rajamani, Amuda, E-mail: amuacademics@gmail.com; Arumugam, Brinda

2017-08-01

Highlights: • We have revised and organised section II. • The expression for H{sub eff} is now expressed clearly. • We have added Appendix which explains the derivation of the solution and the occurrence of the oscillatory factor. - Abstract: The dynamics of magnetic skyrmions is investigated in a composite free layer spin valve nano pillar for different coupling mechanisms in the absence of Dzyaloshinski-Moriya Interaction (DMI). Nano meter sized skyrmions and anti skyrmions are trapped with different helices in the free layer. The spin polarised current under specific choice of system parameters changes the droplet solitons into skyrmions and anti skyrmions. The current driven dynamics is studied and the condition at which an isolated skyrmion exists, is reported. We have optimised the current density (J) and spin wave vector (k) for which Skyrmion Hall Effect (SHE) completely vanishes and as a result the velocity, size and shape of skyrmions are preserved. When the coupling between the composite free layers is changed, skyrmion-anti skyrmion pair and radial skyrmion-chiral skyrmion pair emerge. For the specific values of ‘J’ and ‘k’ these pairs show coupled motion along the layer and hence these pairs could also be used as a bit in the data processing and storage devices. Our investigation ascertains that a single material can host all the localised magnetic structures if the current density, spin wave vector and coupling constant are suitably chosen and tuned. This study would really be of fundamental importance owing to the possible applications in information processing and data storage in skyrmion based logic circuits and magnetic sensors.

Current neutralization of converging ion beams

International Nuclear Information System (INIS)

Mosher, D.

1978-01-01

It is desired to consider the problem of current neutralization of heavy ion beams traversing gas backgrounds in which the conductivity changes due to beam heating and beam convergence. The procedure is to determine Green's-function solutions to the magnetic-diffusion equation derived from Maxwell's equations and an assumed scaler-plasma conductivity sigma for the background-electron current density j/sub e/. The present calculation is more general than some previously carried out in that arbitrary time variations for the beam current j/sub b/ and conductivity are allowed and the calculation is valid for both weak and strong neutralization. Results presented here must be combined with an appropriate energy-balance equation for the heated background in order to obtain the neutralization self-consistently

Multigigahertz beam-current and position monitor

International Nuclear Information System (INIS)

Carlson, R.L.; Stout, L.E.

1985-01-01

A self-integrating magnetic-loop device having a risetime of less than 175 ps has been developed to monitor the temporal behavior of the electron beam current and position within each 3.3-ns micropulse generated by the PHERMEX rf linear accelerator. Beam current is measured with a 2-GHz bandwidth by combining these loops in a four-port hybrid summer. Another application of these loops uses two 180 0 hybrids to give 2-GHz time-resolved beam position to an accuracy of 1 mm. These sensors are nonintrusive to the propagating beam and allow ultrafast beam measurements previously restricted to the technique of recording the Cerenkov-light emission from an intercepting Kapton foil using a streak camera

Optimal Design for Reactivity Ratio Estimation: A Comparison of Techniques for AMPS/Acrylamide and AMPS/Acrylic Acid Copolymerizations

Directory of Open Access Journals (Sweden)

Alison J. Scott

2015-11-01

Full Text Available Water-soluble polymers of acrylamide (AAm and acrylic acid (AAc have significant potential in enhanced oil recovery, as well as in other specialty applications. To improve the shear strength of the polymer, a third comonomer, 2-acrylamido-2-methylpropane sulfonic acid (AMPS, can be added to the pre-polymerization mixture. Copolymerization kinetics of AAm/AAc are well studied, but little is known about the other comonomer pairs (AMPS/AAm and AMPS/AAc. Hence, reactivity ratios for AMPS/AAm and AMPS/AAc copolymerization must be established first. A key aspect in the estimation of reliable reactivity ratios is design of experiments, which minimizes the number of experiments and provides increased information content (resulting in more precise parameter estimates. However, design of experiments is hardly ever used during copolymerization parameter estimation schemes. In the current work, copolymerization experiments for both AMPS/AAm and AMPS/AAc are designed using two optimal techniques (Tidwell-Mortimer and the error-in-variables-model (EVM. From these optimally designed experiments, accurate reactivity ratio estimates are determined for AMPS/AAm (rAMPS = 0.18, rAAm = 0.85 and AMPS/AAc (rAMPS = 0.19, rAAc = 0.86.

Didactical formulation of the Ampère law

International Nuclear Information System (INIS)

Barchiesi, Dominique

2014-01-01

The Ampère law is useful to calculate the magnetostatic field in the cases of distributions of current with high degree of symmetry. Nevertheless the magnetic field produced by a thin straight wire carrying a current I requires the Biot–Savart law and the use of the Ampère law leads to a mistake. A didactical formulation of the Ampère law is proposed to prevent misinterpretations. (letters and comments)

Computer simulation of electron beams. II. Low-cost beam-current reconstruction

International Nuclear Information System (INIS)

de Wolf, D.A.

1985-01-01

Reconstruction of current density in electron beams is complicated by distortion of phase space which can require very fine discretization of the beam into trajectories. An efficient discretization of phase space is exploited, using conservation of charge and current in hypertriangle patches, to reconstruct the current density by fitting Gaussians through the distorted hypertriangles. Advantages and limitations are discussed

Gap Dependent Bifurcation Behavior of a Nano-Beam Subjected to a Nonlinear Electrostatic Pressure

Directory of Open Access Journals (Sweden)

Mohammad Fathalilou

Full Text Available This paper presents a study on the gap dependent bifurcation behavior of an electro statically-actuated nano-beam. The sizedependent behavior of the beam was taken into account by applying the couple stress theory. Two small and large gap distance regimes have been considered in which the intermolecular vdW and Casimir forces are dominant, respectively. It has been shown that changing the gap size can affect the fundamental frequency of the beam. The bifurcation diagrams for small gap distance revealed that by changing the gap size, the number and type of the fixed points can change. However, for large gap regime, where the Casimir force is the dominant intermolecular force, changing the gap size does not affect the quality of the bifurcation behavior.

Assessment of Electron Beam Welding in Shipyard Construction,

Science.gov (United States)

1985-12-01

ELECTRON BEAM APPLICATORS QUESTIONNAIRE 1. Applicators Name: McCay Tool & Engr. Co. 2. Address: 1449 West Lark, Fenton , Mo. 3...had very li tt le undercut and requ ired no cosmet ic pass. TESTING AND RESULTS ’re~t ing wi ~ pt-f’)rimev oil spc inens inl t he- fol lowing manner. 1...Penetration Cosmet . c Accelerating Voltage (KV) 75 70 Beam Current (ma) 115 30 Travel Speed (IPM) 8 18 Beam focus (Amps programmed) 4.38 4.70 Gun to Work

Non-superconducting persistent currents. Des courants permanents mais pas supraconducteurs

Energy Technology Data Exchange (ETDEWEB)

Benoit, A; Mailly, D

1993-03-01

Forecasted ten years ago a quantum effect is evidenced: persistent currents in small non-superconducting loops in a magnetic field at low temperature. The loop (diameter 2.5 micrometer) is etched in a semiconducting structure GaAs/GaAlAs, where the coherence length is 25 [mu]m, the current is measured with a squid on the same chip, a value of 4 nano amps is found which agrees well with the theoretical value of 5 nA.

Dynamic neutral beam current and voltage control to improve beam efficacy in tokamaks

Science.gov (United States)

Pace, D. C.; Austin, M. E.; Bardoczi, L.; Collins, C. S.; Crowley, B.; Davis, E.; Du, X.; Ferron, J.; Grierson, B. A.; Heidbrink, W. W.; Holcomb, C. T.; McKee, G. R.; Pawley, C.; Petty, C. C.; Podestà, M.; Rauch, J.; Scoville, J. T.; Spong, D. A.; Thome, K. E.; Van Zeeland, M. A.; Varela, J.; Victor, B.

2018-05-01

An engineering upgrade to the neutral beam system at the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] enables time-dependent programming of the beam voltage and current. Initial application of this capability involves pre-programmed beam voltage and current injected into plasmas that are known to be susceptible to instabilities that are driven by energetic ( E ≥ 40 keV) beam ions. These instabilities, here all Alfvén eigenmodes (AEs), increase the transport of the beam ions beyond a classical expectation based on particle drifts and collisions. Injecting neutral beam power, P beam ≥ 2 MW, at reduced voltage with increased current reduces the drive for Alfvénic instabilities and results in improved ion confinement. In lower-confinement plasmas, this technique is applied to eliminate the presence of AEs across the mid-radius of the plasmas. Simulations of those plasmas indicate that the mode drive is decreased and the radial extent of the remaining modes is reduced compared to a higher beam voltage case. In higher-confinement plasmas, this technique reduces AE activity in the far edge and results in an interesting scenario of beam current drive improving as the beam voltage reduces from 80 kV to 65 kV.

High spatial precision nano-imaging of polarization-sensitive plasmonic particles

Science.gov (United States)

Liu, Yunbo; Wang, Yipei; Lee, Somin Eunice

2018-02-01

Precise polarimetric imaging of polarization-sensitive nanoparticles is essential for resolving their accurate spatial positions beyond the diffraction limit. However, conventional technologies currently suffer from beam deviation errors which cannot be corrected beyond the diffraction limit. To overcome this issue, we experimentally demonstrate a spatially stable nano-imaging system for polarization-sensitive nanoparticles. In this study, we show that by integrating a voltage-tunable imaging variable polarizer with optical microscopy, we are able to suppress beam deviation errors. We expect that this nano-imaging system should allow for acquisition of accurate positional and polarization information from individual nanoparticles in applications where real-time, high precision spatial information is required.

Glow-discharge-created electron beams and beam-excited lasers

International Nuclear Information System (INIS)

Meyer, J.D.

1989-01-01

Efficiently created glow discharge electron beams have been developed and studied in detail. The beam mode of operation occurs in the abnormal glow adjacent to the glow-to-arc transition regime. In contrast to electron beams generated in high vacuum from thermionic electron emitting sources, this type of discharge creates electrons directly in soft vacuum by secondary electron emission from cold cathode surfaces following the bombardment of the cathode surface by fast ions and neutral atoms. Factors influencing the efficient electron emission from cold cathodes are presented with emphasis on cathode materials. Sintered ceramic-metal cathodes and oxide-coated cathodes are presented, both of which can produce high power, efficiently generated, d.c. electron beams with discharge currents up to 1 amp (∼130 mA/cm 2 ) at volt ages of up to 6 kV. Novel cathode designs and discharge geometries are presented with specific emphasis on both self-focussed beams emitted from circular cathodes and line-source electron beams emitted from rectangular cathodes forming a thin sheet of electrons. Electrostatically focussed line-source electron beams are spatially characterized by experimentally measuring the effect of discharge parameters and cathode design upon the focussed beam width, focal point, and uniformity. This is achieved by scanning a current collecting detector in three dimensions in order to profile the distribution of electron beam current. Discharge electron beams are further characterized by their electron energy distribution. Measured electron flux energy distributions of transmitted beam electrons in the negative glow are compared to theoretical models. The relative effects of elastic and inelastic collisions mechanisms upon both the overall form and detailed structure of the energy distribution are discussed

Shielding properties of the ordinary concrete loaded with micro- and nano-particles against neutron and gamma radiations.

Science.gov (United States)

Mesbahi, Asghar; Ghiasi, Hosein

2018-06-01

The shielding properties of ordinary concrete doped with some micro and nano scaled materials were studied in the current study. Narrow beam geometry was simulated using MCNPX Monte Carlo code and the mass attenuation coefficient of ordinary concrete doped with PbO 2 , Fe 2 O 3 , WO 3 and H 4 B (Boronium) in both nano and micro scales was calculated for photon and neutron beams. Mono-energetic beams of neutrons (100-3000 keV) and photons (142-1250 keV) were used for calculations. The concrete doped with nano-sized particles showed higher neutron removal cross section (7%) and photon attenuation coefficient (8%) relative to micro-particles. Application of nano-sized material in the composition of new concretes for dual protection against neutrons and photons are recommended. For further studies, the calculation of attenuation coefficients of these nano-concretes against higher energies of neutrons and photons and different particles are suggested. Copyright © 2018 Elsevier Ltd. All rights reserved.

Limiting currents of overcompensated electron beams

International Nuclear Information System (INIS)

Malafaev, V.A.

1990-01-01

A possibility of producing recompensated electron beam and increasing its limiting currents in the magnetic field is experimentally investigated. It is shown that such a possibility is realized when the beam is surrounded by a cylindrical net placed into the tube located under the positive potential relative to the net. In this case an increase of limiting current at the expense of increasing the ion life time, takes place. Current, exceeding the Pierce threshold 1.5 times, is obtained

Current neutralization in ballistic transport of light ion beams

International Nuclear Information System (INIS)

Hubbard, R.F.; Slinker, S.P.; Lampe, M.; Joyce, G.; Ottinger, P.

1992-01-01

Intense light ion beams are being considered as drivers to ignite fusion targets in the Laboratory Microfusion Facility (LMF). Ballistic transport of these beams from the diode to the target is possible only if the beam current is almost completely neutralized by plasma currents. This paper summarizes related work on relativistic electron beam and heavy ion beam propagation and describes a simple simulation model (DYNAPROP) which has been modified to treat light ion beam propagation. DYNAPROP uses an envelope equation to treat beam dynamics and uses rate equations to describe plasma and conductivity generation. The model has been applied both to the high current, 30 MeV Li +3 beams for LMF as well as low current, 1.2 MeV proton beams which are currently being studied on GAMBLE B at the Naval Research Laboratory. The predicted ratio of net currents to beam current is ∼0.1--0.2 for the GAMBLE experiment and ∼0.01 for LMF. The implications of these results for LMF and the GAMBLE experiments art discussed in some detail. The simple resistive model in DYNAPROP has well-known limitations in the 1 torr regime which arise primarily from the neglect of plasma electron transport. Alternative methods for treating the plasma response are discussed

Development of high current electron beam generator

Energy Technology Data Exchange (ETDEWEB)

Lee, Byeong Cheol; Lee, Jong Min; Kim, Sun Kook [and others

1997-05-01

A high-current electron beam generator has been developed. The energy and the average current of the electron beam are 2 MeV and 50 mA, respectively. The electron beam generator is composed of an electron gun, RF acceleration cavities, a 260-kW RF generator, electron beam optics components, and control system, etc. The electron beam generator will be used for the development of a millimeter-wave free-electron laser and a high average power infrared free-electron laser. The machine will also be used as a user facility in nuclear industry, environment industry, semiconductor industry, chemical industry, etc. (author). 15 tabs., 85 figs.

Development of high current electron beam generator

International Nuclear Information System (INIS)

Lee, Byeong Cheol; Lee, Jong Min; Kim, Sun Kook

1997-05-01

A high-current electron beam generator has been developed. The energy and the average current of the electron beam are 2 MeV and 50 mA, respectively. The electron beam generator is composed of an electron gun, RF acceleration cavities, a 260-kW RF generator, electron beam optics components, and control system, etc. The electron beam generator will be used for the development of a millimeter-wave free-electron laser and a high average power infrared free-electron laser. The machine will also be used as a user facility in nuclear industry, environment industry, semiconductor industry, chemical industry, etc. (author). 15 tabs., 85 figs

Digital DC beam current measurement on SSRF storage ring

International Nuclear Information System (INIS)

Xiong Liang; Yin Chongxian; Liu Ming; Chen Jianfeng

2011-01-01

Both DC current transformer (DCCT) and integrating current transformer (ICT) can be used in DC beam current measurement. The ICT has strong capability of resisting electromagnetic interference, but its measurement accuracy cannot satisfy the DC beam current measurement requirement when using traditional high speed A/D. With high resolution A/D and equivalent sampling system, DC beam current measuring system based on ICT can reach high accuracy compared with DCCT system. In this paper, the ICT-based DC beam current measurement, equivalent sampling method and testing results at Shanghai Synchrotron Radiation Facility(SSRF) is described. (authors)

Beam current monitors in the NLCTA

International Nuclear Information System (INIS)

Nantista, C.; Adolphsen, C.

1997-05-01

The current profile along the 126 ns, multi-bunch beam pulse in the Next Linear Collider Test Accelerator (NLCTA) is monitored with fast toroids (rise time ∼ 1 ns). Inserted at several positions along the beam line, they allow one to track current transmission as a function of position along the bunch train. Various measurements, such as rise time, current, width, and slope, are made on the digitized signals, which can be corrected in software by means of stored frequency response files. The design and implementation of these devices is described

Characterisation Of The Beam Plasma In High Current, Low Energy Ion Beams For Implanters

International Nuclear Information System (INIS)

Fiala, J.; Armour, D. G.; Berg, J. A. van der; Holmes, A. J. T.; Goldberg, R. D.; Collart, E. H. J.

2006-01-01

The effective transport of high current, positive ion beams at low energies in ion implanters requires the a high level of space charge compensation. The self-induced or forced introduction of electrons is known to result in the creation of a so-called beam plasma through which the beam propagates. Despite the ability of beams at energies above about 3-5 keV to create their own neutralising plasmas and the development of highly effective, plasma based neutralising systems for low energy beams, very little is known about the nature of beam plasmas and how their characteristics and capabilities depend on beam current, beam energy and beamline pressure. These issues have been addressed in a detailed scanning Langmuir probe study of the plasmas created in beams passing through the post-analysis section of a commercial, high current ion implanter. Combined with Faraday cup measurements of the rate of loss of beam current in the same region due to charge exchange and scattering collisions, the probe data have provided a valuable insight into the nature of the slow ion and electron production and loss processes. Two distinct electron energy distribution functions are observed with electron temperatures ≥ 25 V and around 1 eV. The fast electrons observed must be produced in their energetic state. By studying the properties of the beam plasma as a function of the beam and beamline parameters, information on the ways in which the plasma and the beam interact to reduce beam blow-up and retain a stable plasma has been obtained

Bipolar power sources for the correction magnets of AmPS

International Nuclear Information System (INIS)

Es, J.T. van; Luigjes, G.; Trigt, J.H. van.

1992-01-01

AmPS consists of many correction magnets which must provide the currents. These currents serve continuously between -3 Amp and +3 Amp. The adjusted current must be stable inside 0,1%. The copper resistance of magnet coils and their wires are ≤ 8 ohm and the self induction is 200 mH. An extended market research on power supplies has enabled the authors to decide to develop it themselves. This development has led to a module system with Bitbus control. (authors). 14 figs., 4 tabs

Imaging of current density distributions with a Nb weak-link scanning nano-SQUID microscope

Science.gov (United States)

Shibata, Yusuke; Nomura, Shintaro; Kashiwaya, Hiromi; Kashiwaya, Satoshi; Ishiguro, Ryosuke; Takayanagi, Hideaki

2015-10-01

Superconducting quantum interference devices (SQUIDs) are accepted as one of the highest magnetic field sensitive probes. There are increasing demands to image local magnetic fields to explore spin properties and current density distributions in a two-dimensional layer of semiconductors or superconductors. Nano-SQUIDs have recently attracting much interest for high spatial resolution measurements in nanometer-scale samples. Whereas weak-link Dayem Josephson junction nano-SQUIDs are suitable to miniaturization, hysteresis in current-voltage (I-V) characteristics that is often observed in Dayem Josephson junction is not desirable for a scanning microscope. Here we report on our development of a weak-link nano-SQUIDs scanning microscope with small hysteresis in I-V curve and on reconstructions of two-dimensional current density vector in two-dimensional electron gas from measured magnetic field.

Electron-Beam Produced Air Plasma: Optical Measurement of Beam Current

Science.gov (United States)

Vidmar, Robert; Stalder, Kenneth; Seeley, Megan

2006-10-01

Experiments to quantify the electron beam current and distribution of beam current in air plasma are discussed. The air plasma is produced by a 100-keV 10-mA electron beam source that traverses a transmission window into a chamber with air as a target gas. Air pressure is between 1 mTorr and 760 Torr. Strong optical emissions due to electron impact ionization are observed for the N2 2^nd positive line at 337.1 nm and the N2^+ 1^st negative line at 391.4 nm. Calibration of optical emissions using signals from the isolated transmission window and a Faraday plate are discussed. The calibrated optical system is then used to quantify the electron distribution in the air plasma.

Closed-form solution for static pull-in voltage of electrostatically actuated clamped-clamped micro/nano beams under the effect of fringing field and van der Waals force

Science.gov (United States)

Bhojawala, V. M.; Vakharia, D. P.

2017-12-01

This investigation provides an accurate prediction of static pull-in voltage for clamped-clamped micro/nano beams based on distributed model. The Euler-Bernoulli beam theory is used adapting geometric non-linearity of beam, internal (residual) stress, van der Waals force, distributed electrostatic force and fringing field effects for deriving governing differential equation. The Galerkin discretisation method is used to make reduced-order model of the governing differential equation. A regime plot is presented in the current work for determining the number of modes required in reduced-order model to obtain completely converged pull-in voltage for micro/nano beams. A closed-form relation is developed based on the relationship obtained from curve fitting of pull-in instability plots and subsequent non-linear regression for the proposed relation. The output of regression analysis provides Chi-square (χ 2) tolerance value equals to 1  ×  10-9, adjusted R-square value equals to 0.999 29 and P-value equals to zero, these statistical parameters indicate the convergence of non-linear fit, accuracy of fitted data and significance of the proposed model respectively. The closed-form equation is validated using available data of experimental and numerical results. The relative maximum error of 4.08% in comparison to several available experimental and numerical data proves the reliability of the proposed closed-form equation.

In Vivo Cardiovascular Pharmacology of 2′,3′-cAMP, 2′-AMP, and 3′-AMP in the Rat

Science.gov (United States)

Mi, Zaichuan

2013-01-01

The naturally occurring purine 2′,3′-cAMP is metabolized in vitro to 2′-AMP and 3′-AMP, which are subsequently metabolized to adenosine. Whether in vivo 2′,3′-cAMP, 2′-AMP, or 3′-AMP are rapidly converted to adenosine and exert rapid effects via adenosine receptors is unknown. To address this question, we compared the cardiovascular and renal effects of 2′,3′-cAMP, 2′-AMP, 3′-AMP, 3′,5′-cAMP, 5′-AMP, and adenosine in vivo in the rat. Purines were infused intravenously while monitoring mean arterial blood pressure (MABP), heart rate (HR), cardiac output, and renal and mesenteric blood flows. Total peripheral (TPR), renal vascular (RVR), and mesenteric vascular (MVR) resistances were calculated. Urine was collected for determination of urine excretion rate [urine volume (UV)]. When sufficient urine was available, the sodium excretion rate (Na+ER) and glomerular filtration rate (GFR) were determined. 2′,3′-cAMP, 2′-AMP, and 3′-AMP dose-dependently and profoundly reduced MABP, HR, TPR, and MVR with efficacy and potency similar to adenosine and 5′-AMP. These effects of 2′,3′-cAMP, 2′-AMP, and 3′-AMP were attenuated by blockade of adenosine receptors with 1,3-dipropyl-8-(p-sulfophenyl)xanthine. 2′,3′-cAMP, 2′-AMP, 3′-AMP, adenosine, and 5′-AMP variably affected RVR, but profoundly (nearly 100%) decreased UV at higher doses. GFR and Na+ER could be measured at the lower doses and were suppressed by 2′,3′-cAMP, 2′-AMP, and 3′-AMP, but not by adenosine or 5′-AMP. 2′,3′-cAMP increased urinary excretion rates of 2′-AMP, 3′-AMP, and adenosine. 3′,5′-cAMP exerted no adverse hemodynamic effects yet increased urinary adenosine as efficiently as 2′,3′-cAMP. Conclusions: In vivo 2′,3′-cAMP is rapidly converted to adenosine. Because both cAMPs increase adenosine in the urinary compartment, these agents may provide unique therapeutic opportunities. PMID:23759508

Ponderomotive enhancement of charged particle beam limiting current

International Nuclear Information System (INIS)

Grebogi, C.; Uhm, H.S.

1987-01-01

The space charge limiting current problem is investigated for a magnetized particle beam propagating in a cylindrical drift tube and in presence of a waveguide mode. It is shown that with a proper choice of a waveguide mode, the limiting current can be greatly enhanced due to ponderomotive effects. Physically, this is accomplished by using the ponderomotive energy to reduce the potential depression due to the beam's self space charge field. Formulas for the limiting current as a function of beam energy and waveguide r.f. field for solid and hollow beams are derived. It is found from these formulas that, in appropriate parameter regimes, the space charge limiting current, say, of a 250kV bem can be enhanced by 70%

Neutral beam current drive scaling in DIII-D

International Nuclear Information System (INIS)

Porter, G.D.; Bhadra, D.K.; Burrell, K.H.

1989-03-01

Neutral beam current drive scaling experiments have been carried out on the DIII-D tokamak at General Atomics. These experiments were performed using up to 10 MW of 80 keV hydrogen beams. Previous current drive experiments on DIII-D have demonstrated beam driven currents up to 340 kA. In the experiments reported here we achieved beam driven currents of at least 500 kA, and have obtained operation with record values of poloidal beta (εβ/sub p/ = 1.4). The beam driven current reported here is obtained from the total plasma current by subtracting an estimate of the residual Ohmic current determined from the measured loop voltage. In this report we discuss the scaling of the current drive efficiency with plasma conditions. Using hydrogen neutral beams, we find the current drive efficiency is similar in Deuterium and Helium target plasmas. Experiments have been performed with plasma electron temperatures up to T/sub e/ = 3 keV, and densities in the range 2 /times/ 10 19 m/sup /minus/3/ 19 m/sup /minus/3/. The current drive efficiency (nIR/P) is observed to scale linearly with the energy confinement time on DIII-D to a maximum of 0.05 /times/ 10 20 m/sup /minus/2/ A/W. The measured efficiency is consistent with a 0-D theoretical model. In addition to comparison with this simple model, detailed analysis of several shots using the time dependent transport code ONETWO is discussed. This analysis indicates that bootstrap current contributes approximately 10--20% of the the total current. Our estimates of this effect are somewhat uncertain due to limited measurements of the radial profile of the density and temperatures. 4 refs., 1 fig., 1 tab

High current beam transport experiments at GSI

International Nuclear Information System (INIS)

Klabunde, J.; Schonlein, A.; Spadtke, P.

1985-01-01

The status of the high current ion beam transport experiment is reported. 190 keV Ar 1+ ions were injected into six periods of a magnetic quadrupole channel. Since the pulse length is > 0.5 ms partial space charge neutralization occurs. In our experiments, the behavior of unneutralized and partially space charge compensated beams is compared. With an unneutralized beam, emittance growth has been measured for high intensities even in case of the zero-current phase advance sigma 0 0 . This initial emittance growth at high tune depression we attribute to the homogenization effect of the space charge density. An analytical formula based on this assumption describes the emittance growth very well. Furthermore the predicted envelope instabilities for sigma 0 > 90 0 were observed even after 6 periods. In agreement with the theory, unstable beam transport was also experimentally found if a beam with different emittances in the two transverse phase planes was injected into the transport channel. Although the space charge force is reduced for a partially neutralized beam a deterioration of the beam quality was measured in a certain range of beam parameters. Only in the range where an unneutralized beam shows the initial emittance growth, the partial neutralization reduces this effect, otherwise the partially neutralized beam is more unstable

Versatile high current metal ion implantation facility

International Nuclear Information System (INIS)

Brown, I.G.; Dickinson, M.R.; Galvin, J.E.; Godechot, X.; MacGill, R.A.

1992-01-01

A metal ion implantation facility has been developed with which high current beams of practically all the solid metals of the periodic table can be produced. A multicathode, broad-beam, metal vapor vacuum arc ion source is used to produce repetitively pulsed metal ion beams at an extraction voltage of up to 100 kV, corresponding to an ion energy of up to several hundred kiloelectronvolts because of the ion charge state multiplicity, and with a beam current of up to several amps peak pulsed and several tens of milliamps time averaged delivered onto a downstream target. Implantation is done in a broad-beam mode, with a direct line of sight from ion source to target. Here we summarize some of the features of the ion source and the implantation facility that has been built up around it. (orig)

cAMP signalling in the vasculature: the role of Epac (exchange protein directly activated by cAMP).

Science.gov (United States)

Roberts, Owain Llŷr; Dart, Caroline

2014-02-01

The second messenger cAMP plays a central role in mediating vascular smooth muscle relaxation in response to vasoactive transmitters and in strengthening endothelial cell-cell junctions that regulate the movement of solutes, cells and macromolecules between the blood and the surrounding tissue. The vasculature expresses three cAMP effector proteins: PKA (protein kinase A), CNG (cyclic-nucleotide-gated) ion channels, and the most recently discovered Epacs (exchange proteins directly activated by cAMP). Epacs are a family of GEFs (guanine-nucleotide-exchange factors) for the small Ras-related GTPases Rap1 and Rap2, and are being increasingly implicated as important mediators of cAMP signalling, both in their own right and in parallel with the prototypical cAMP target PKA. In the present paper, we review what is currently known about the role of Epac within blood vessels, particularly with regard to the regulation of vascular tone, endothelial barrier function and inflammation.

Current density monitor for intense relativistic electron beams

International Nuclear Information System (INIS)

Fiorito, R.B.; Raleigh, M.; Seltzer, S.M.

1986-01-01

We describe a new type of electric probe which is capable of measuring the time-resolved current density profile of a stable, reproducible, high-energy (>4-MeV) high-current (>1-kA) electron beam. The sensing element of this probe is an open-ended but capped-off 50-Ω coaxial line constructed of graphite. The graphite sensor is 4.3 mm in diameter, 6 cm long, and is range thin to the primary beam electrons. The probe produces a signal proportional to the intercepted beam current. When the sensor is scanned radially through the beam during repeated pulses, a curve of signal versus depth of insertion is produced from which the radial current density profile can be determined. Measurements are presented of the profile of the electron beam from the Experimental Test Accelerator (4.5 MeV, 10 kA) at Lawrence Livermore National Laboratory. Good agreement is shown between measurements made with this probe and the beam radius as predicted by transport codes. The advantage of the electric probe lies in its ruggedness, simplicity, inherent fast rise time, and low cost. In contrast to other systems it requires no radiation shielding, water cooling, or auxiliary support equipment to operate in an intense beam environment

Electron gun for formation of two high-current beams

International Nuclear Information System (INIS)

Borisov, A.R.; Zherlitsyn, A.G.; Mel'nikov, G.V.; Shtejn, Yu.G.

1982-01-01

The design of the ''Tonus'' accelerator electron gun for formation of two high-current beams aiming at the production of the maximum beam power and density is described. The results of investigation of two modes of beam formation are presented. In the first variant the beams were produced by means of two plane diodes with 40 mm diameter cathodes made of stainless steel and anodes made of 50 μm thick titanium foil. In the second variant the beams were formed by means of two coaxial diodes with magnetic insulation. In one diode the cathode diameter equals to 74 mm, the anode diameter - 92 mm, in the other diode 16 and 44 mm respectively. Current redistribution in the diodes and its effect on accelerating voltage are investigated. It is shown that the gun permits formation of synchronized two high-current beams, iaving equal electron energied. Wide range current control of both beams is possible

Nonequivalence of the magnetostatic potential energy corresponding to the Ampère and Grassmann current element force formulas

International Nuclear Information System (INIS)

Minteer, Timothy M

2013-01-01

The equivalence of the Ampère and Grassmann (Biot–Savart/Lorentz) current element force formulas is well established. However, when the magnetostatic potential energy corresponding to these force formulas is evaluated, the formulas are found to be nonequivalent. The historical current element force formulas are first presented. The magnetostatic potential energy corresponding to these historical current element force formulas are then analysed. The end result establishes the Grassmann and Neumann current element force formulas as the only commonly referenced formulas giving the correct magnetostatic potential energy for circuital currents. (paper)

FMIT direct-current beam monitor

International Nuclear Information System (INIS)

Brousseau, A.T.; Chamberlin, D.D.

1981-01-01

The prototype injector section for the Fusion Materials Irradiation Test (FMIT) Facility being developed at the Los Alamos National Laboratory requires that beam parameters be noninterceptively monitored. This report describes the application of a single toroidal core, coupled with very simple circuitry, that results in the production of a simple instrument, and eliminates the problems inherent in the Faraday cup technique for the current measurements of the FMIT injector beam

Multi-pulsed intense electron beam emission from velvet, carbon fibers, carbon nano-tubes and dispenser cathodes

International Nuclear Information System (INIS)

Xia Liansheng; Yang Anmin; Chen Yi; Zhang Huang; Liu Xingguang; Li Jin; Jiang Xiaoguo; Zhang Kaizhi; Shi Jinshui; Deng Jianjun; Zhang Linwen

2010-01-01

The experimental results of studies of four kinds of cathode emitting intense electron beams are demonstrated under multi-pulsed mode based on an experimental setup including two multi-pulse high voltage sources. The tested cathodes include velvet, carbon fibers, carbon nano-tubes (CNTs) and dispenser cathodes. The results indicate that all four are able to emit multi-pulsed beams. For velvet, carbon fiber and CNTs, the electron induced cathode plasma emission may be the main process and this means that there are differences in beam parameters from pulse to pulse. For dispenser cathodes tested in the experiment, although there is a little difference from pulse to pulse for some reason, thermal-electric field emission may be the main process. (authors)

On the limiting stationary currents of relativistic electron beams

International Nuclear Information System (INIS)

Kavchuk, V.N.; Kondratenko, A.N.

1987-01-01

The problem on electron beam transport in the system of different configurations both vacuum and filled with gas or plasma is connected with the problem of the limiting current, which can conduct such systems. Two models of a vacuum relativistic electron beam (REB) are considered. It is shown that there is upper limit for the value of the external magnetic field, H 0 , in the model of isovelocity REB with the constant longitudinal beam particle rate, β z =const. Estimation of the limiting current of REB as a series of inverse power H 0 is obtained. Estimations of the limiting current of magnetized hallow REB with thin walls are obtained in another model with β z ≠ const. Determination used in this case of the limiting current is directly connected with ''trapping'' of the beam central part due to formation of a virtual cathode and based on consideration of uniflux electron motion in the beam. Such an approach allows to obtain estimations of the limiting current of the thin-wall hallow beam. In this case an upper limit for the thickness of the beam wall is connected with the bottom limit for the value of the external magnetic field providing radial beam equilibrium

Investigation based on nano-electromechanical system double Si3N4 resonant beam pressure sensor.

Science.gov (United States)

Yang, Chuan; Guo, Can; Yuan, Xiaowei

2011-12-01

This paper presents a type of NEMS (Nano-Electromechanical System) double Si3N4 resonant beams pressure sensor. The mathematical models are established in allusion to the Si3N4 resonant beams and pressure sensitive diaphragm. The distribution state of stress has been analyzed theoretically based on the mathematical model of pressure sensitive diaphragm; from the analysis result, the position of the Si3N4 resonant beams above the pressure sensitive diaphragm was optimized and then the dominance observed after the double resonant beams are adopted is illustrated. From the analysis result, the position of the Si3N4 resonant beams above the pressure sensitive diaphragm is optimized, illustrating advantages in the adoption of double resonant beams. The capability of the optimized sensor was generally analyzed using the ANSYS software of finite element analysis. The range of measured pressure is 0-400 Kpa, the coefficient of linearity correlation is 0.99346, and the sensitivity of the sensor is 498.24 Hz/Kpa, higher than the traditional sensors. Finally the processing techniques of the sensor chip have been designed with sample being successfully processed.

Absolute beam current monitoring in endstation c

International Nuclear Information System (INIS)

Bochna, C.

1995-01-01

The first few experiments at CEBAF require approximately 1% absolute measurements of beam currents expected to range from 10-25μA. This represents errors of 100-250 nA. The initial complement of beam current monitors are of the non intercepting type. CEBAF accelerator division has provided a stripline monitor and a cavity monitor, and the authors have installed an Unser monitor (parametric current transformer or PCT). After calibrating the Unser monitor with a precision current reference, the authors plan to transfer this calibration using CW beam to the stripline monitors and cavity monitors. It is important that this be done fairly rapidly because while the gain of the Unser monitor is quite stable, the offset may drift on the order of .5μA per hour. A summary of what the authors have learned about the linearity, zero drift, and gain drift of each type of current monitor will be presented

Nano-scale gene delivery systems; current technology, obstacles, and future directions.

Science.gov (United States)

Garcia-Guerra, Antonio; Dunwell, Thomas L; Trigueros, Sonia

2018-01-07

Within the different applications of nanomedicine currently being developed, nano-gene delivery is appearing as an exciting new technique with the possibility to overcome recognised hurdles and fulfill several biological and medical needs. The central component of all delivery systems is the requirement for the delivery of genetic material into cells, and for them to eventually reside in the nucleus where their desired function will be exposed. However, genetic material does not passively enter cells; thus, a delivery system is necessary. The emerging field of nano-gene delivery exploits the use of new materials and the properties that arise at the nanometre-scale to produce delivery vectors that can effectively deliver genetic material into a variety of different types of cells. The novel physicochemical properties of the new delivery vectors can be used to address the current challenges existing in nucleic acid delivery in vitro and in vivo. While there is a growing interest in nanostructure-based gene delivery, the field is still in its infancy, and there is yet much to discover about nanostructures and their physicochemical properties in a biological context. We carry out an organized and focused search of bibliographic databases. Our results suggest that despite new breakthroughs in nanostructure synthesis and advanced characterization techniques, we still face many barriers in producing highly efficient and non-toxic delivery systems. In this review, we overview the types of systems currently used for clinical and biomedical research applications along with their advantages and disadvantages, as well as discussing barriers that arise from nano-scale interactions with biological material. In conclusion, we hope that by bringing the far reaching multidisciplinary nature of nano-gene delivery to light, new targeted nanotechnology-bases strategies are developed to overcome the major challenges covered in this review. Copyright© Bentham Science Publishers; For

Current-Voltage Characteristic of Nanosecond - Duration Relativistic Electron Beam

Science.gov (United States)

Andreev, Andrey

2005-10-01

The pulsed electron-beam accelerator SINUS-6 was used to measure current-voltage characteristic of nanosecond-duration thin annular relativistic electron beam accelerated in vacuum along axis of a smooth uniform metal tube immersed into strong axial magnetic field. Results of these measurements as well as results of computer simulations performed using 3D MAGIC code show that the electron-beam current dependence on the accelerating voltage at the front of the nanosecond-duration pulse is different from the analogical dependence at the flat part of the pulse. In the steady-state (flat) part of the pulse), the measured electron-beam current is close to Fedosov current [1], which is governed by the conservation law of an electron moment flow for any constant voltage. In the non steady-state part (front) of the pulse, the electron-beam current is higher that the appropriate, for a giving voltage, steady-state (Fedosov) current. [1] A. I. Fedosov, E. A. Litvinov, S. Ya. Belomytsev, and S. P. Bugaev, ``Characteristics of electron beam formed in diodes with magnetic insulation,'' Soviet Physics Journal (A translation of Izvestiya VUZ. Fizika), vol. 20, no. 10, October 1977 (April 20, 1978), pp.1367-1368.

AMP is an adenosine A1 receptor agonist.

Science.gov (United States)

Rittiner, Joseph E; Korboukh, Ilia; Hull-Ryde, Emily A; Jin, Jian; Janzen, William P; Frye, Stephen V; Zylka, Mark J

2012-02-17

Numerous receptors for ATP, ADP, and adenosine exist; however, it is currently unknown whether a receptor for the related nucleotide adenosine 5'-monophosphate (AMP) exists. Using a novel cell-based assay to visualize adenosine receptor activation in real time, we found that AMP and a non-hydrolyzable AMP analog (deoxyadenosine 5'-monophosphonate, ACP) directly activated the adenosine A(1) receptor (A(1)R). In contrast, AMP only activated the adenosine A(2B) receptor (A(2B)R) after hydrolysis to adenosine by ecto-5'-nucleotidase (NT5E, CD73) or prostatic acid phosphatase (PAP, ACPP). Adenosine and AMP were equipotent human A(1)R agonists in our real-time assay and in a cAMP accumulation assay. ACP also depressed cAMP levels in mouse cortical neurons through activation of endogenous A(1)R. Non-selective purinergic receptor antagonists (pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid and suramin) did not block adenosine- or AMP-evoked activation. Moreover, mutation of His-251 in the human A(1)R ligand binding pocket reduced AMP potency without affecting adenosine potency. In contrast, mutation of a different binding pocket residue (His-278) eliminated responses to AMP and to adenosine. Taken together, our study indicates that the physiologically relevant nucleotide AMP is a full agonist of A(1)R. In addition, our study suggests that some of the physiological effects of AMP may be direct, and not indirect through ectonucleotidases that hydrolyze this nucleotide to adenosine.

Noise reduction in the beam current monitor

International Nuclear Information System (INIS)

Arai, Shigeaki.

1982-02-01

A simple noise reduction system using a pulse transformer and a pair of L C low pass filters has been introduced to the beam current monitor of a current transformer type at the INS electron linac. With this system, the pick-up noise has been reduced to be 1% of the noise without noise reduction. Signal deformation caused by this system is relatively small and the beam current pulse down to 20 mA is successfully monitored in the actual accelerator operation. (author)

Bootstrap current of fast ions in neutral beam injection heating

International Nuclear Information System (INIS)

Huang Qianhong; Gong Xueyu; Yang Lei; Li Xinxia; Lu Xingqiang; Yu Jun

2012-01-01

The bootstrap current of fast ions produced by the neutral beam injection is investigated in a large aspect ratio tokamak with circular cross-section under specific parameters. The bootstrap current density distribution and the total bootstrap current are figured out. In addition, the beam bootstrap current always accompanies the electron return current due to the parallel momentum transfer from fast ions. With the electron return current considered, the net current density obviously decreases due to electron return current, at the same time the peak of current moves towards the centre plasma. Numerical results show that the value of the net current depends sensitively not only on the angle of the neutral beam injection but also on the ratio of the velocity of fast ions to the critical velocity: the value of net current is small for the neutral beam parallel injection but increases multipliedly for perpendicular injection, and increases with beam energy increasing. (authors)

Integrated lithography to prepare periodic arrays of nano-objects

International Nuclear Information System (INIS)

Sipos, Áron; Szalai, Anikó; Csete, Mária

2013-01-01

We present an integrated lithography method to prepare versatile nano-objects with variable shape and nano-scaled substructure, in wavelength-scaled periodic arrays with arbitrary symmetry. The idea is to illuminate colloid sphere monolayers by polarized beams possessing periodic lateral intensity modulations. Finite element method was applied to determine the effects of the wavelength, polarization and angle of incidence of the incoming beam, and to predict the characteristics of nano-objects, which can be fabricated on thin metal layer covered substrates due to the near-field enhancement under silica colloid spheres. The inter-object distance is controlled by varying the relative orientation of the periodic intensity modulation with respect to the silica colloid sphere monolayer. It is shown that illuminating silica colloid sphere monolayers by two interfering beams, linear patterns made of elliptical holes appear in case of linear polarization, while circularly polarized beams result in co-existent rounded objects, as more circular nano-holes and nano-crescents. The size of the nano-objects and their sub-structure is determined by the spheres diameter and by the wavelength. We present various complex plasmonic patterns made of versatile nano-objects that can be uniquely fabricated applying the inherent symmetry breaking possibilities in the integrated lithography method.

Vertically etched silicon nano-rods as a sensitive electron detector

International Nuclear Information System (INIS)

Hajmirzaheydarali, M; Akbari, M; Soleimani-Amiri, S; Sadeghipari, M; Shahsafi, A; Akhavan Farahani, A; Mohajerzadeh, S

2015-01-01

We have used vertically etched silicon nano-rods to realize electron detectors suitable for scanning electron microscopes. The results of deep etching of silicon nano-structures are presented to achieve highly ordered arrays of nano-rods. The response of the electron detector to energy of the primary electron beam and the effects of various sizes and materials has been investigated, indicating its high sensitivity to secondary and back-scattered electrons. The miniaturized structure of this electron detector allows it to be placed in the vicinity of the specimen to improve the resolution and contrast. This detector collects electrons and converts the electron current to voltage directly by means of n-doped silicon nano-rods on a p-type silicon substrate. Silicon nano-rods enhance the surface-to-volume ratio of the detector as well as improving the yield of electron detection. The use of nano-structures and silicon nanowires as an electron detector has led to higher sensitivities than with micro-structures. (paper)

Effects of neutral particle beam on nano-crystalline silicon thin films, with application to thin film transistor backplane for flexible active matrix organic light emitting diodes

International Nuclear Information System (INIS)

Jang, Jin Nyoung; Song, Byoung Chul; Lee, Dong Hyeok; Yoo, Suk Jae; Lee, Bonju; Hong, MunPyo

2011-01-01

A novel deposition process for nano-crystalline silicon (nc-Si) thin films was developed using neutral beam assisted chemical vapor deposition (NBaCVD) technology for the application of the thin film transistor (TFT) backplane of flexible active matrix organic light emitting diode (AMOLED). During the formation of a nc-Si thin film, the energetic particles enhance nano-sized crystalline rather microcrystalline Si in thin films. Neutral Particle Beam (NPB) affects the crystallinity in two ways: (1) NPB energy enhances nano-crystallinity through kinetic energy transfer and chemical annealing, and (2) heavier NPB (such as Ar) induces damage and amorphization through energetic particle impinging. Nc-Si thin film properties effectively can be changed by the reflector bias. As increase of NPB energy limits growing the crystalline, the performance of TFT supports this NPB behavior. The results of nc-Si TFT by NBaCVD demonstrate the technical potentials of neutral beam based processes for achieving high stability and reduced leakage in TFT backplanes for AMOLEDs.

Analytic approximations to nonlinear boundary value problems modeling beam-type nano-electromechanical systems

Energy Technology Data Exchange (ETDEWEB)

Zou, Li [Dalian Univ. of Technology, Dalian City (China). State Key Lab. of Structural Analysis for Industrial Equipment; Liang, Songxin; Li, Yawei [Dalian Univ. of Technology, Dalian City (China). School of Mathematical Sciences; Jeffrey, David J. [Univ. of Western Ontario, London (Canada). Dept. of Applied Mathematics

2017-06-01

Nonlinear boundary value problems arise frequently in physical and mechanical sciences. An effective analytic approach with two parameters is first proposed for solving nonlinear boundary value problems. It is demonstrated that solutions given by the two-parameter method are more accurate than solutions given by the Adomian decomposition method (ADM). It is further demonstrated that solutions given by the ADM can also be recovered from the solutions given by the two-parameter method. The effectiveness of this method is demonstrated by solving some nonlinear boundary value problems modeling beam-type nano-electromechanical systems.

Fabrication of nano-sized magnetic tunnel junctions using lift-off process assisted by atomic force probe tip.

Science.gov (United States)

Jung, Ku Youl; Min, Byoung-Chul; Ahn, Chiyui; Choi, Gyung-Min; Shin, Il-Jae; Park, Seung-Young; Rhie, Kungwon; Shin, Kyung-Ho

2013-09-01

We present a fabrication method for nano-scale magnetic tunnel junctions (MTJs), employing e-beam lithography and lift-off process assisted by the probe tip of atomic force microscope (AFM). It is challenging to fabricate nano-sized MTJs on small substrates because it is difficult to use chemical mechanical planarization (CMP) process. The AFM-assisted lift-off process enables us to fabricate nano-sized MTJs on small substrates (12.5 mm x 12.5 mm) without CMP process. The e-beam patterning has been done using bi-layer resist, the poly methyl methacrylate (PMMA)/ hydrogen silsesquioxane (HSQ). The PMMA/HSQ resist patterns are used for both the etch mask for ion milling and the self-aligned mask for top contact formation after passivation. The self-aligned mask buried inside a passivation oxide layer, is readily lifted-off by the force exerted by the probe tip. The nano-MTJs (160 nm x 90 nm) fabricated by this method show clear current-induced magnetization switching with a reasonable TMR and critical switching current density.

Fabrication of high-aspect-ratio nano structures using a nano x-ray shadow mask

International Nuclear Information System (INIS)

Kim, Yong Chul; Lee, Seung S

2008-01-01

This paper describes a novel method for the fabrication of high-aspect-ratio nano structures (HAR-nano structures) using a nano x-ray shadow mask and deep x-ray lithography (DXRL). The nano x-ray shadow mask is fabricated by depositing an x-ray absorber layer (Au, 3 µm) onto the back side of a nano shadow mask. The nano shadow mask is produced with nano-sized apertures whose dimensions are reduced to several tens of nanometers by the accumulation of low-stress silicon nitride (Si x N y ) using the LPCVD process on the shadow mask. A shadow mask containing apertures with a size of 1 µm is fabricated on a bulk micromachined Si x N y membrane. The thickness of an absorber layer must be in the range of several tens of micrometers in order to obtain a contrast of more than 100 for the conventional DXRL process at the Pohang Light Source (PLS). However, a 3 µm thick absorber layer can provide a sufficient contrast if the modified DXRL of the central beam-stop method is used, which blocks high-energy x-rays. A nano shadow mask with 30 nm sized apertures is fabricated and a nano x-ray shadow mask with 250 nm sized apertures is fabricated by depositing a 3 µm thick absorber layer on a nano shadow mask with 500 nm sized apertures. HAR-nano structures (circles with a diameter of 420 nm and lines with a width of 274 nm) with aspect ratios of over 10:1 on a 3.2 µm SU-8 are successfully fabricated by using the nano x-ray shadow mask and the central beam-stop method

The intense slow positron beam facility at the PULSTAR reactor and applications in nano-materials study

Energy Technology Data Exchange (ETDEWEB)

Liu, Ming; Moxom, Jeremy; Hawari, Ayman I. [Nuclear Reactor Program, Department of Nuclear Engineering, North Carolina State University, P.O. Box 7909, Raleigh, NC 27695 (United States); Gidley, David W. [Department of Physics, University of Michigan, 450 Church Street, Ann Arbor MI 48109 (United States)

2013-04-19

An intense slow positron beam has been established at the PULSTAR nuclear research reactor of North Carolina State University. The slow positrons are generated by pair production in a tungsten moderator from gammarays produced in the reactor core and by neutron capture reactions in cadmium. The moderated positrons are electrostatically extracted and magnetically guided out of the region near the core. Subsequently, the positrons are used in two spectrometers that are capable of performing positron annihilation lifetime spectroscopy (PALS) and positron Doppler broadening spectroscopy (DBS) to probe the defect and free volume properties of materials. One of the spectrometers (e{sup +}-PALS) utilizes an rf buncher to produce a pulsed beam and has a timing resolution of 277 ps. The second spectrometer (Ps-PALS) uses a secondary electron timing technique and is dedicated to positronium lifetime measurements with an approximately 1 ns timing resolution. PALS measurements have been conducted in the e{sup +}-PALS spectrometer on a series of nano-materials including organic photovoltaic thin films, membranes for filtration, and polymeric fibers. These studies have resulted in understanding some critical issues related to the development of the examined nano-materials.

The intense slow positron beam facility at the PULSTAR reactor and applications in nano-materials study

Science.gov (United States)

Liu, Ming; Moxom, Jeremy; Hawari, Ayman I.; Gidley, David W.

2013-04-01

An intense slow positron beam has been established at the PULSTAR nuclear research reactor of North Carolina State University. The slow positrons are generated by pair production in a tungsten moderator from gammarays produced in the reactor core and by neutron capture reactions in cadmium. The moderated positrons are electrostatically extracted and magnetically guided out of the region near the core. Subsequently, the positrons are used in two spectrometers that are capable of performing positron annihilation lifetime spectroscopy (PALS) and positron Doppler broadening spectroscopy (DBS) to probe the defect and free volume properties of materials. One of the spectrometers (e+-PALS) utilizes an rf buncher to produce a pulsed beam and has a timing resolution of 277 ps. The second spectrometer (Ps-PALS) uses a secondary electron timing technique and is dedicated to positronium lifetime measurements with an approximately 1 ns timing resolution. PALS measurements have been conducted in the e+-PALS spectrometer on a series of nano-materials including organic photovoltaic thin films, membranes for filtration, and polymeric fibers. These studies have resulted in understanding some critical issues related to the development of the examined nano-materials.

Controlling hollow relativistic electron beam orbits with an inductive current divider

Energy Technology Data Exchange (ETDEWEB)

Swanekamp, S. B.; Richardson, A. S.; Angus, J. R.; Cooperstein, G.; Hinshelwood, D. D.; Ottinger, P. F.; Rittersdorf, I. M.; Schumer, J. W.; Weber, B. V.; Zier, J. C. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States)

2015-02-15

A passive method for controlling the trajectory of an intense, hollow electron beam is proposed using a vacuum structure that inductively splits the beam's return current. A central post carries a portion of the return current (I{sub 1}), while the outer conductor carries the remainder (I{sub 2}). An envelope equation appropriate for a hollow electron beam is derived and applied to the current divider. The force on the beam trajectory is shown to be proportional to (I{sub 2}-I{sub 1}), while the average force on the envelope (the beam width) is proportional to the beam current I{sub b} = (I{sub 2} + I{sub 1}). The values of I{sub 1} and I{sub 2} depend on the inductances in the return-current path geometries. Proper choice of the return-current geometries determines these inductances and offers control over the beam trajectory. Solutions using realistic beam parameters show that, for appropriate choices of the return-current-path geometry, the inductive current divider can produce a beam that is both pinched and straightened so that it approaches a target at near-normal incidence with a beam diameter that is on the order of a few mm.

Neutral beam current drive with balanced injection

International Nuclear Information System (INIS)

Eckhartt, D.

1990-01-01

Current drive with fast ions has proved its capability to sustain a tokamak plasma free of externally induced electric fields in a stationary state. The suprathermal ion population within the toroidal plasma was created by quasi-tangential and uni-directional injection of high-energy neutral atoms, their ionisation and subsequent deceleration by collisions with the background plasma particles. In future large tokamaks of the NET/INTER-type, with reactor-relevant values of plasma density and temperature, this current drive scheme is expected to maintain the toroidal current at the plasma centre, as current drive by lower hybrid waves will be restricted to the outer plasma regions owing to strong wave damping. Adequate penetration of the neutral atoms through the dense plasma requires particle energies of several hundred kilovolts per nucleon since beam absorption scales roughly with the ratio beam energy over density. The realisation of such high-energy high-power neutral beams, based on negative ion technology, is now under study. (author) 7 refs., 2 figs

AMP Is an Adenosine A1 Receptor Agonist*

Science.gov (United States)

Rittiner, Joseph E.; Korboukh, Ilia; Hull-Ryde, Emily A.; Jin, Jian; Janzen, William P.; Frye, Stephen V.; Zylka, Mark J.

2012-01-01

Numerous receptors for ATP, ADP, and adenosine exist; however, it is currently unknown whether a receptor for the related nucleotide adenosine 5′-monophosphate (AMP) exists. Using a novel cell-based assay to visualize adenosine receptor activation in real time, we found that AMP and a non-hydrolyzable AMP analog (deoxyadenosine 5′-monophosphonate, ACP) directly activated the adenosine A1 receptor (A1R). In contrast, AMP only activated the adenosine A2B receptor (A2BR) after hydrolysis to adenosine by ecto-5′-nucleotidase (NT5E, CD73) or prostatic acid phosphatase (PAP, ACPP). Adenosine and AMP were equipotent human A1R agonists in our real-time assay and in a cAMP accumulation assay. ACP also depressed cAMP levels in mouse cortical neurons through activation of endogenous A1R. Non-selective purinergic receptor antagonists (pyridoxalphosphate-6-azophenyl-2′,4′-disulfonic acid and suramin) did not block adenosine- or AMP-evoked activation. Moreover, mutation of His-251 in the human A1R ligand binding pocket reduced AMP potency without affecting adenosine potency. In contrast, mutation of a different binding pocket residue (His-278) eliminated responses to AMP and to adenosine. Taken together, our study indicates that the physiologically relevant nucleotide AMP is a full agonist of A1R. In addition, our study suggests that some of the physiological effects of AMP may be direct, and not indirect through ectonucleotidases that hydrolyze this nucleotide to adenosine. PMID:22215671

The Bootstrap Current and Neutral Beam Current Drive in DIII-D

International Nuclear Information System (INIS)

Politzer, P.A.

2005-01-01

Noninductive current drive is an essential part of the implementation of the DIII-D Advanced Tokamak program. For an efficient steady-state tokamak reactor, the plasma must provide close to 100% bootstrap fraction (f bs ). For noninductive operation of DIII-D, current drive by injection of energetic neutral beams [neutral beam current drive (NBCD)] is also important. DIII-D experiments have reached ∼80% bootstrap current in stationary discharges without inductive current drive. The remaining current is ∼20% NBCD. This is achieved at β N [approximately equal to] β p > 3, but at relatively high q 95 (∼10). In lower q 95 Advanced Tokamak plasmas, f bs ∼ 0.6 has been reached in essentially noninductive plasmas. The phenomenology of high β p and β N plasmas without current control is being studied. These plasmas display a relaxation oscillation involving repetitive formation and collapse of an internal transport barrier. The frequency and severity of these events increase with increasing β, limiting the achievable average β and causing modulation of the total current as well as the pressure. Modeling of both bootstrap and NBCD currents is based on neoclassical theory. Measurements of the total bootstrap and NBCD current agree with calculations. A recent experiment based on the evolution of the transient voltage profile after an L-H transition shows that the more recent bootstrap current models accurately describe the plasma behavior. The profiles and the parametric dependences of the local neutral beam-driven current density have not yet been compared with theory

Fast Beam Current Change Monitor for the LHC

CERN Document Server

Kral, Jan

Stringent demands on the LHC safety and protection systems require improved methods of detecting fast beam losses. The Fast Beam Current Transformer (FBCT) is a measurement instrument, providing information about bunch-to-bunch intensity of the accelerated beam. This thesis describes the development of a new protection system based on the FBCT signal measurements. This system, the Fast Beam Current Change Monitor (FBCCM), measures the FBCT signal in a narrow frequency band and computes time derivation of the beam signal magnitude. This derivation is proportional to the beam losses. When the losses exceed a certain level, the FBCCM requests a beam dump in order to protect the LHC. The LHC protection will be ensured by four FBCCMs which will be installed into the LHC in July 2014. Six FBCCMs have been already constructed and their characteristics were measured with satisfactory results. The FBCCMs were tested by a laboratory simulation of the real LHC environment.

Light‐driven Nano­‐robotics - Invited Plenary Presentation, IEEE NANO 2016

DEFF Research Database (Denmark)

Glückstad, Jesper

) and pioneering their use in so-called lightdriven nano-robotics. Hence, the aim of our latest R&D is to combine advanced topology optimisation, 3D printing of functionalized materials and light manipulation to demonstrate a structure-mediated micro-tonano coupling paradigm for controlled operation of robotic...... tools overcoming the diffraction limit while still being optically visible and manoeuvrable. 2PP-fabrication can already today create intricate nano-features merged onto larger microstructures that, in turn, are steerable by dynamic light beams. Applying multiple independently controllable laser beam...... traps on these structures will enable real-time light-driven nanorobotics with six-degrees-of-freedom. This sets the stage for new discoveries using calibrated steering of optimally shaped and functionalized nano-tools at the subcellular level and in full 3D - not available in the scientifi c world...

High-energy tritium beams as current drivers in tokamak reactors

International Nuclear Information System (INIS)

Mikkelsen, D.R.; Grisham, L.R.

1983-04-01

The effect on neutral-beam design and reactor performance of using high-energy (approx. 3-10 MeV) tritium neutral beams to drive steady-state tokamak reactors is considered. The lower current of such beams leads to several advantages over lower-energy neutral beams. The major disadvantage is the reduction of the reactor output caused by the lower current-drive efficiency of the high-energy beams

Competitive cAMP Antagonists for cAMP-Receptor Proteins

NARCIS (Netherlands)

Haastert, Peter J.M. van; Driel, Roel van; Jastorff, Bernd; Baraniak, Janina; Stec, Wojciech J.; Wit, René J.W. de

1984-01-01

The two exocyclic oxygen atoms at phosphorus of cAMP have been replaced by a sulfur atom or by a dimethylamino group. These substitutions introduce chirality at the phosphorus atom; therefore, two diastereoisomers are known for each derivative: (SP)-cAMPS, (RP)-cAMPS, (SP)-cAMPN(CH3)2, and

Analysis of Biot-Savart’s law in comparison with Ampère’s force between current elements

Directory of Open Access Journals (Sweden)

Hugo Shigueo Tanaka dos Santos

2017-12-01

Full Text Available Nowadays, we use Biot-Savart’s Law and Grassmann’s force to study the magnetic fields effects. We can observe that this force apparently do not always satisfy the principle of action and reaction. In contrast, Ampère’s force always satisfies this principle explicitly and always along the straight line connecting the two currents elements. The present work presents a historic analysis of the development of these two forces, which have been developed based on interpretations of the Ørsted’s experiment. We also compare these two forces in order to verify if both have the same result. We show that the Grassmann’s expression, in fact, does not satisfy to the principle of action and reaction. Ampère’s force not only follows the principle of action and reaction in the strongest way, but it also explains the phenomena based action at a distance, which is easier to be observed and has many other powerful results, not only in the electromagnetism. In order to compare these two approaches, we calculate the force that an infinite rectilinear wire exerts on a loop of conductive material, both with current.

Nano-ranged low-energy ion-beam-induced DNA transfer in biological cells

Energy Technology Data Exchange (ETDEWEB)

Yu, L.D., E-mail: yuld@fnrf.science.cmu.ac.th [Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Wongkham, W. [Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Prakrajang, K. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Sangwijit, K.; Inthanon, K. [Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thongkumkoon, P. [Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Wanichapichart, P. [Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Membrane Science and Technology Research Center, Department of Physics, Faculty of Science, Prince of Songkla University, Hat Yai, Songkla 90112 (Thailand); Anuntalabhochai, S. [Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

2013-06-15

Low-energy ion beams at a few tens of keV were demonstrated to be able to induce exogenous macromolecules to transfer into plant and bacterial cells. In the process, the ion beam with well controlled energy and fluence bombarded living cells to cause certain degree damage in the cell envelope in nanoscales to facilitate the macromolecules such as DNA to pass through the cell envelope and enter the cell. Consequently, the technique was applied for manipulating positive improvements in the biological species. This physical DNA transfer method was highly efficient and had less risk of side-effects compared with chemical and biological methods. For better understanding of mechanisms involved in the process, a systematic study on the mechanisms was carried out. Applications of the technique were also expanded from DNA transfer in plant and bacterial cells to DNA transfection in human cancer cells potentially for the stem cell therapy purpose. Low-energy nitrogen and argon ion beams that were applied in our experiments had ranges of 100 nm or less in the cell envelope membrane which was majorly composed of polymeric cellulose. The ion beam bombardment caused chain-scission dominant damage in the polymer and electrical property changes such as increase in the impedance in the envelope membrane. These nano-modifications of the cell envelope eventually enhanced the permeability of the envelope membrane to favor the DNA transfer. The paper reports details of our research in this direction.

Nano-ranged low-energy ion-beam-induced DNA transfer in biological cells

International Nuclear Information System (INIS)

Yu, L.D.; Wongkham, W.; Prakrajang, K.; Sangwijit, K.; Inthanon, K.; Thongkumkoon, P.; Wanichapichart, P.; Anuntalabhochai, S.

2013-01-01

Low-energy ion beams at a few tens of keV were demonstrated to be able to induce exogenous macromolecules to transfer into plant and bacterial cells. In the process, the ion beam with well controlled energy and fluence bombarded living cells to cause certain degree damage in the cell envelope in nanoscales to facilitate the macromolecules such as DNA to pass through the cell envelope and enter the cell. Consequently, the technique was applied for manipulating positive improvements in the biological species. This physical DNA transfer method was highly efficient and had less risk of side-effects compared with chemical and biological methods. For better understanding of mechanisms involved in the process, a systematic study on the mechanisms was carried out. Applications of the technique were also expanded from DNA transfer in plant and bacterial cells to DNA transfection in human cancer cells potentially for the stem cell therapy purpose. Low-energy nitrogen and argon ion beams that were applied in our experiments had ranges of 100 nm or less in the cell envelope membrane which was majorly composed of polymeric cellulose. The ion beam bombardment caused chain-scission dominant damage in the polymer and electrical property changes such as increase in the impedance in the envelope membrane. These nano-modifications of the cell envelope eventually enhanced the permeability of the envelope membrane to favor the DNA transfer. The paper reports details of our research in this direction.

Control of renin secretion from rat juxtaglomerular cells by cAMP-specific phosphodiesterases

DEFF Research Database (Denmark)

Friis, Ulla G; Jensen, Boye L; Sethi, Shala

2002-01-01

, and the PDE4 inhibitor rolipram enhanced cellular cAMP content. Dialysis of single JG cells with cAMP in whole-cell patch-clamp experiments led to concentration-dependent, biphasic changes in cell membrane capacitance (C(m)) with a marked increase in C(m) at 1 micromol/L, no net change at 10 micromol....../L, and a decrease at 100 micromol/L cAMP. cGMP also had a dual effect on C(m) at 10-fold higher concentration compared with cAMP. Trequinsin, milrinone, and rolipram mimicked the effect of cAMP on C(m). Trequinsin, cAMP, and cGMP enhanced outward current 2- to 3-fold at positive membrane potentials. The effects...... of cAMP, cGMP, and trequinsin on C(m) and cell currents were abolished by inhibition of protein kinase A with Rp-cAMPs. We conclude that degradation of cAMP by PDE3 and PDE4 contributes to regulation of renin release from JG cells. Our data provide evidence at the cellular level that stimulation...

Bootstrap current of fast ions in neutral beam injection heating

International Nuclear Information System (INIS)

Huang Qianhong; Gong Xueyu; Li Xinxia; Yu Jun

2012-01-01

The bootstrap current of fast ions produced by neutral beam injection (NBI) is investigated in a large-aspect-ratio tokamak with circular cross-section under specific parameters. The bootstrap current density distribution and the total bootstrap current are reported. In addition, the beam bootstrap current always accompanies the electron return current due to the parallel momentum transfer from fast ions. With the electron return current taken into consideration, the net current density obviously decreases; at the same time, the peak of the current moves towards the central plasma. Numerical results show that the value of the net current depends sensitively not only on the angle of the NBI but also on the ratio of the velocity of fast ions to the critical velocity: the value of the net current is small for neutral beam parallel injection, but increases severalfold for perpendicular injection, and increases with increasing beam energy. (paper)

The development of beam current monitors in the APS

International Nuclear Information System (INIS)

Wang, X.; Lenkszus, F.; Rotela, E.

1995-01-01

The Advanced Photon Source (APS) is a third-generation 7-GeV synchrotron radiation source. The precision measurement of beam current is a challenging task in high energy accelerators, such as the APS, with a wide range of beam parameters and complicated noise, radiation, and thermal environments. The beam pulses in the APS injector and storage ring have charge ranging from 50pC to 25nC with pulse durations varying from 30ps to 30ns. A total of nine non- intercepting beam current monitors have been installed in the APS facility (excluding those in the linac) for general current measurement. In addition, several independent current monitors with specially designed redundant interlock electronics are installed for personnel safety and machine protection. This paper documents the design and development of current monitors in the APS,. discusses the commissioning experience in the past year, and presents the results of recent operations

Microstructure cantilever beam for current measurement

Directory of Open Access Journals (Sweden)

M.T.E. Khan

2010-01-01

Full Text Available Most microelectromechanical systems (MEMS sensors are based on the microcantilever technology, which uses a broad range of design materials and structures. The benefit ofMEMStechnology is in developing devices with a lower cost, lower power consumption, higher performance and greater integration. A free-end cantilever beam with a magnetic material mass has been designed using MEMS software tools. The magnetic material was used to improve the sensitivity of the cantilever beam to an externally-applied magnetic field. The cantilever was designed to form a capacitance transducer, which consisted of variable capacitance where electrical and mechanical energies were exchanged. The aim of this paper was to analyse the system design of the microcantilever when subjected to a magnetic field produced by a current-carrying conductor. When the signal, a sinusoidal current with a constant frequency, was applied, the cantilever beam exhibited a vibration motion along the vertical axis when placed closer to the line current. This motion created corresponding capacitance changes and generated a voltage output proportional to the capacitive change in the signal-processing circuitry attached to the microcantilever. The equivalent massspring system theory was used to describe and analyse the effect of the natural frequency of the system vibrations and motion due to the applied magnetic field, in a single-degree of freedom. The main application of this microcantilever is in current measurements to develop a non-contact current sensor mote.

Beam position and total current monitor for heavy ion fusion beams

International Nuclear Information System (INIS)

Berners, D.; Reginato, L.L.

1992-10-01

Heavy Ion Fusion requires moderate currents, 1-10A, for a duration of about 1 μs. For accurate beam transport, the center of charge must be located to within ± 100 μm. Beam position and intensity may be excited at frequencies approaching 10 MHz, and the monitoring system must have adequate bandwidth to respond at these frequencies. We have modified the Rogowski technique by using distributed reactance multiturn magnetic loops so that it is suitable for measuring current position as well as amplitude. Four identical stripline coils are wound one per quadrant around a non magnetic core. The sensitivity is similar to that of a lumped coil system, with the added advantage of increased bandwidth. The voltages induced on the four separate coils are compared and suitable signal conditioning is performed to recover beam position and intensity information

Reduction of space charge breakdown in e-beam irradiated nano/polymethyl methacrylate composites

International Nuclear Information System (INIS)

Zheng Feihu; Zhang Yewen; An Zhenlian; Dong Jianxing; Lei Qingquan

2013-01-01

Fast discharge of numerous space charges in dielectric materials can cause space charge breakdown. This letter reports the role of nanoparticles in affecting space charge breakdown of nano/polymethyl methacrylate composites. Space charge distributions in the composites, implanted by electron beam irradiation, were measured by pressure wave propagation method. The results show that the nanoparticles have significant effects on the isothermal charge decay and space charge breakdown in the nanocomposites. The resistance to space charge breakdown in the nanocomposites is attributed to the combined action of the introduction of deep trapping states and the scattering effect by the added nanoparticles.

Cryogenic current comparators for precise ion beam current measurements

International Nuclear Information System (INIS)

Kurian, Febin

2015-01-01

The planned Facility for Antiproton and Ion Research (FAIR) at GSI has to cope with a wide range of beam intensities in its high-energy beam transport systems and in the storage rings. To meet the requirements of a non-intercepting intensity measurement down to nA range, it is planned to install a number of Cryogenic Current Comparator (CCC) units at different locations in the FAIR beamlines. In this work, the first CCC system for intensity measurement of heavy ion beams, which was developed at GSI, was re-commissioned and upgraded to be used as a 'GSI - CCC prototype' for extensive optimization and development of an improved CCC for FAIR. After installation of a new SQUID sensor and related electronics, as well as implementation of improved data acquisition components, successful beam current measurements were performed at a SIS18 extraction line. The measured intensity values were compared with those of a Secondary Electron Monitor (SEM). Furthermore, the spill-structure of a slowly extracted beam was measured and analyzed, investigating its improvement due to bunching during the slow-extraction process. Due to the extreme sensitivity of the superconducting sensor, the determined intensity values as well as the adjustment of the system for optimal performance are strongly influenced by the numerous noise sources of the accelerators environment. For this reason, detailed studies of different effects caused by noise have been carried out, which are presented together with proposals to reduce them. Similarly, studies were performed to increase the dynamic range and overcome slew rate limitations, the results of which are illustrated and discussed as well. By combining the various optimizations and characterizations of the GSI CCC prototype with the experiences made during beam operation, criteria for a more efficient CCC System could be worked out, which are presented in this work. The details of this new design are worked out with respect to the

Development of an external Faraday cup for beam current measurements

International Nuclear Information System (INIS)

Kim, Kye-Ryung; Jung, Myung-Hwan; Ra, Se-Jin; Lee, Seok-Ki

2010-01-01

In general, beam current measurements are very important for many kinds of experiments using highly energetic particle beams at accelerators, such as cyclotrons, linacs, etc. The Faraday cup is known to be one of the most popular beam current measurement tools. We developed an external Faraday cup to measure the beam current at a dedicated beam line for low-flux experiments installed at the MC-50 cyclotron of Korea Institute of Radiological and Medical Sciences (KIRAMS). It was designed for external beam current measurements and is composed of a vacuum chamber, an entrance window, a collimator, a electrostatic suppressor ring, and a cup. The window is made of 75-um-thick Kapton film, and the diameter of the collimator is 10 mm or 20 mm. The ring and the cup has 5-cm inner diameters, and the thickness of the bottom of the cup is 2 cm, which is enough to absorb the total proton energy up to 45 MeV. Using this external Faraday cup, we measured the beam current from the cyclotron, and we compared measured flux to the results from film dosimetry using GAF films.

Theory of current-drive in plasmas

International Nuclear Information System (INIS)

Fisch, N.J.

1986-12-01

The continuous operation of a tokamak fusion reactor requires, among other things, a means of providing continuous toroidal current. Such operation is preferred to the conventional pulsed operation, where the plasma current is induced by a time-varying magnetic field. A variety of methods has been proposed to provide continuous current, including methods which utilize particle beams or radio frequency waves in any of several frequency regimes. Currents as large as half a mega-amp have now been produced in the laboratory by such means, and experimentation in these techniques has now involved major tokamak facilities worldwide

Beam brilliance investigation of high current ion beams at GSI heavy ion accelerator facility.

Science.gov (United States)

Adonin, A A; Hollinger, R

2014-02-01

In this work the emittance measurements of high current Ta-beam provided by VARIS (Vacuum Arc Ion Source) ion source are presented. Beam brilliance as a function of beam aperture at various extraction conditions is investigated. Influence of electrostatic ion beam compression in post acceleration gap on the beam quality is discussed. Use of different extraction systems (single aperture, 7 holes, and 13 holes) in order to achieve more peaked beam core is considered. The possible ways to increase the beam brilliance are discussed.

High-current Standing Wave Linac With Gyrocon Power Source

CERN Document Server

Karliner, M M; Makarov, I G; Nezhevenko, O A; Ostreiko, G N; Persov, B Z; Serdobintsev, G V

2004-01-01

A gyrocon together with high-voltage 1.5 MeV accelerator ELIT-3A represents a power generator at 430 MHz serving for linear electron accelerator pulse driving. The facility description and results of calorimetric measurements of ELIT-3A electron beam power and accelerated beam at the end of accelerator are presented in the paper. 2.2 amps of pulsed current have been obtained at electron energy of 20 MeV. The achieved energy conversion efficiency is about 55%.

Range of Possible Beam Current in Linac4

CERN Document Server

Lallement, J-B; CERN. Geneva. BE Department

2009-01-01

Linac4 is a new accelerator under construction at CERN. It is designed to accelerate H- ions to 160MeV, for injection into the existing Proton Synchrotron Booster (PSB). It is also the front-end of the SPL Linac, a high energy proton driver that will reach the energy of 5GeV. The Linac baseline design has been done for a nominal beam peak current of 70mA but it will certainly have to deal with different currents. 132 out of 155 quadrupoles in the Linac are permanent magnets, this choice of using PMQ having fixed gradient, mainly in the DTL and in the CCDTL may then entail issues concerning the beam transverse matching and quality from current different from the nominal one. In this paper, we present the beam dynamics performances in Linac4 obtained for different currents.

MEK Inhibitors Reverse cAMP-Mediated Anxiety in Zebrafish

DEFF Research Database (Denmark)

Lundegaard, Pia R.; Anastasaki, Corina; Grant, Nicola J.

2015-01-01

Altered phosphodiesterase (PDE)-cyclic AMP (cAMP) activity is frequently associated with anxiety disorders, but current therapies act by reducing neuronal excitability rather than targeting PDE-cAMP-mediated signaling pathways. Here, we report the novel repositioning of anti-cancer MEK inhibitors...... as anxiolytics in a zebrafish model of anxiety-like behaviors. PDE inhibitors or activators of adenylate cyclase cause behaviors consistent with anxiety in larvae and adult zebrafish. Small-molecule screening identifies MEK inhibitors as potent suppressors of cAMP anxiety behaviors in both larvae and adult...... zebrafish, while causing no anxiolytic behavioral effects on their own. The mechanism underlying cAMP-induced anxiety is via crosstalk to activation of the RAS-MAPK signaling pathway. We propose that targeting crosstalk signaling pathways can be an effective strategy for mental health disorders, and advance...

The physics of high current beams

International Nuclear Information System (INIS)

Lawson, J.D.

1988-05-01

An outline is presented of paraxial charged particle optics in the presence of self-fields arising from the space-charge and current carried by the beam. Solutions of the envelope equations for beams with finite emittance are considered for a number of specific situations, with the approximation that the density profile of the beam is uniform with a sharp edge, so that the focusing remains linear. More realistic beams are then considered, and the problems of matching, emittance growth and stability are discussed. An attempt is made to emphasize physical principles and physical ideas rather than to present the detailed mathematical techniques required for specific problems. The approach is a tutorial one, and several 'exercises' are included in the text. Most of the material is treated in more depth in the author's forthcoming book. (author)

Beam-current monitor for FMIT

International Nuclear Information System (INIS)

Chamberlin, D.D.; Brousseau, A.T.

1981-03-01

The application of a single toroidal core, coupled with very simple circuitry, that results in the production of a simple instrument, and eliminates the problems inherent in the Faraday cup technique for the current measurements of the FMIT injector beam is described

Focused particle beam nano-machining: the next evolution step towards simulation aided process prediction

International Nuclear Information System (INIS)

Plank, Harald

2015-01-01

During the last decade, focused ion beam processing has been developed from traditionally used Ga + liquid ion sources towards higher resolution gas field ion sources (He + and Ne + ). Process simulations not only improve the fundamental understanding of the relevant ion–matter interactions, but also enable a certain predictive power to accelerate advances. The historic ‘gold’ standard in ion–solid simulations is the SRIM/TRIM Monte Carlo package released by Ziegler, Ziegler and Biersack 2010 Nucl. Instrum. Methods B 268 1818–23. While SRIM/TRIM is very useful for a myriad of applications, it is not applicable for the understanding of the nanoscale evolution associated with ion beam nano-machining as the substrate does not evolve with the sputtering process. As a solution for this problem, a new, adapted simulation code is briefly overviewed and finally addresses these contributions. By that, experimentally observed Ne + beam sputter profiles can be explained from a fundamental point of view. Due to their very good agreement, these simulations contain the potential for computer aided optimization towards predictable sputter processes for different nanotechnology applications. With these benefits in mind, the discussed simulation approach represents an enormous step towards a computer based master tool for adaptable ion beam applications in the context of industrial applications. (viewpoint)

A multiwire secondary emission profile monitor for small emittance beams

International Nuclear Information System (INIS)

Chehab, R.; Bonnard, J.; Humbert, G.; Leblond, B.; Saury, J.L.

1985-01-01

A secondary emission monitor using two multiwire grids separated by a positively biased collector has been constructed and tested with a 1 GeV electron beam at the Orsay Linac. The monitor installed just before the electron-positron converter has 8 gold-plated-tungsten wires of 0.1 mm diameter equally spaced 0.2 mm apart in each plane. Each wire is connected with an integrator using a low-bias current operational amplifier. The wire planes and the collector are moved into the beam by a stepping motor : that allows beam-position verification. We measured narrow profiles for 1 Amp peak current pulses of 30 nanoseconds width. Profiles are displayed on a scope and allow emittance determination by the three gradient method. Such a monitor is very useful to control the electron beam position and dimensions on the converter, because the positron source dimensions are rather bigger than those of the incident beam and the geometrical acceptance of the positron Linac is limited

Schwann Cells Metabolize Extracellular 2′,3′-cAMP to 2′-AMP

Science.gov (United States)

Verrier, Jonathan D.; Kochanek, Patrick M.

2015-01-01

The 3′,5′-cAMP–adenosine pathway (3′,5′-cAMP→5′-AMP→adenosine) and the 2′,3′-cAMP–adenosine pathway (2′,3′-cAMP→2′-AMP/3′-AMP→adenosine) are active in the brain. Oligodendrocytes participate in the brain 2′,3′-cAMP–adenosine pathway via their robust expression of 2′,3′-cyclic nucleotide 3′-phosphodiesterase (CNPase; converts 2′,3′-cAMP to 2′-AMP). Because Schwann cells also express CNPase, it is conceivable that the 2′,3′-cAMP–adenosine pathway exists in the peripheral nervous system. To test this and to compare the 2′,3′-cAMP–adenosine pathway to the 3′,5′-cAMP–adenosine pathway in Schwann cells, we examined the metabolism of 2′,3′-cAMP, 2′-AMP, 3′-AMP, 3′,5′-cAMP, and 5′-AMP in primary rat Schwann cells in culture. Addition of 2′,3′-cAMP (3, 10, and 30 µM) to Schwann cells increased levels of 2′-AMP in the medium from 0.006 ± 0.002 to 21 ± 2, 70 ± 3, and 187 ± 10 nM/µg protein, respectively; in contrast, Schwann cells had little ability to convert 2′,3′-cAMP to 3′-AMP or 3′,5′-cAMP to either 3′-AMP or 5′-AMP. Although Schwann cells slightly converted 2′,3′-cAMP and 2′-AMP to adenosine, they did so at very modest rates (e.g., 5- and 3-fold, respectively, more slowly compared with our previously reported studies in oligodendrocytes). Using transected myelinated rat sciatic nerves in culture medium, we observed a time-related increase in endogenous intracellular 2′,3′-cAMP and extracellular 2′-AMP. These findings indicate that Schwann cells do not have a robust 3′,5′-cAMP–adenosine pathway but do have a 2′,3′-cAMP–adenosine pathway; however, because the pathway mostly involves 2′-AMP formation rather than 3′-AMP, and because the conversion of 2′-AMP to adenosine is slow, metabolism of 2′,3′-cAMP mostly results in the accumulation of 2′-AMP. Accumulation of 2′-AMP in peripheral nerves postinjury could have

Discovery of a cAMP Deaminase That Quenches Cyclic AMP-Dependent Regulation

Science.gov (United States)

Goble, Alissa M.; Feng, Youjun; Raushel, Frank M.; Cronan, John E.

2013-01-01

An enzyme of unknown function within the amidohydrolase superfamily was discovered to catalyze the hydrolysis of the universal second messenger, cyclic-3’, 5’-adenosine monophosphate (cAMP). The enzyme, which we have named CadD, is encoded by the human pathogenic bacterium Leptospira interrogans. Although CadD is annotated as an adenosine deaminase, the protein specifically deaminates cAMP to cyclic-3’, 5’-inosine monophosphate (cIMP) with a kcat/Km of 2.7 ± 0.4 × 105 M−1 s−1 and has no activity on adenosine, adenine, or 5’-adenosine monophosphate (AMP). This is the first identification of a deaminase specific for cAMP. Expression of CadD in Escherichia coli mimics the loss of adenylate cyclase in that it blocks growth on carbon sources that require the cAMP-CRP transcriptional activator complex for expression of the cognate genes. The cIMP reaction product cannot replace cAMP as the ligand for CRP binding to DNA in vitro and cIMP is a very poor competitor of cAMP activation of CRP for DNA binding. Transcriptional analyses indicate that CadD expression represses expression of several cAMP-CRP dependent genes. CadD adds a new activity to the cAMP metabolic network and may be a useful tool in intracellular study of cAMP-dependent processes. PMID:24074367

Broad-beam, high current, metal ion implantation facility

International Nuclear Information System (INIS)

Brown, I.G.; Dickinson, M.R.; Galvin, J.E.; Godechot, X.; MacGill, R.A.

1990-07-01

We have developed a high current metal ion implantation facility with which high current beams of virtually all the solid metals of the Periodic Table can be produced. The facility makes use of a metal vapor vacuum arc ion source which is operated in a pulsed mode, with pulse width 0.25 ms and repetition rate up to 100 pps. Beam extraction voltage is up to 100 kV, corresponding to an ion energy of up to several hundred keV because of the ion charge state multiplicity; beam current is up to several Amperes peak and around 10 mA time averaged delivered onto target. Implantation is done in a broad-beam mode, with a direct line-of-sight from ion source to target. Here we describe the facility and some of the implants that have been carried out using it, including the 'seeding' of silicon wafers prior to CVD with titanium, palladium or tungsten, the formation of buried iridium silicide layers, and actinide (uranium and thorium) doping of III-V compounds. 16 refs., 6 figs

Thermal and mechanical properties of palm oil-based polyurethane acrylate/ clay nano composites prepared by in-situ intercalative method and electron beam radiation

International Nuclear Information System (INIS)

Salih, A.M.; Mansor Ahmad; Nor Azowa Ibrahim; Rida Tajau; Wan Mohd Zin Wan Yunus

2013-01-01

Full-text: Palm oil based-polyurethane acrylate (POBUA)/ clay nano composites were prepared via in-situ intercalative polymerization using epoxidized palm oil acrylate (EPOLA) and 4,4 ' methylene diphenyl diisocyante (MDI). Organically modified Montmorillonite (ODA-MMT) was incorporated in EPOLA (1, 3 and 5 % wt), and then subjected to polycondensation reaction with MDI. Nano composites solid films were obtained successfully by electron beam radiation induced free radical polymerization (curing). FTIR results reveal that the prepolymer was obtained successfully, with nano clay dispersed in the matrix. The intercalation of the clay in the polymer matrix was investigated by XRD and the interlayer spacing of clay was found to be increased up to 37 Angstrom, while the structure morphology of the nano composites was investigated by TEM and SEM. The nano composites were found to be a mixture of exfoliated and intercalated morphologies. The thermal stability of the nano composites was significantly increased by incorporation of nano clay into the polymer matrix. DSC results reveal that the T g was shifted to higher values, gradually with increasing the amount of filler in the nano composites. Tensile strength and Young's modulus of the nano composites showed remarkable improvement compared to the neat POBUA. (author)

Bolt beam propagation analysis

Science.gov (United States)

Shokair, I. R.

BOLT (Beam on Laser Technology) is a rocket experiment to demonstrate electron beam propagation on a laser ionized plasma channel across the geomagnetic field in the ion focused regime (IFR). The beam parameters for BOLT are: beam current I(sub b) = 100 Amps, beam energy of 1--1.5 MeV (gamma =3-4), and a Gaussian beam and channel of radii r(sub b) = r(sub c) = 1.5 cm. The N+1 ionization scheme is used to ionize atomic oxygen in the upper atmosphere. This scheme utilizes 130 nm light plus three IR lasers to excite and then ionize atomic oxygen. The limiting factor for the channel strength is the energy of the 130 nm laser, which is assumed to be 1.6 mJ for BOLT. At a fixed laser energy and altitude (fixing the density of atomic oxygen), the range can be varied by adjusting the laser tuning, resulting in a neutralization fraction axial profile of the form: f(z) = f(sub 0) e(exp minus z)/R, where R is the range. In this paper we consider the propagation of the BOLT beam and calculate the range of the electron beam taking into account the fact that the erosion rates (magnetic and inductive) vary with beam length as the beam and channel dynamically respond to sausage and hose instabilities.

Dynamic nano-imaging of label-free living cells using electron beam excitation-assisted optical microscope

Science.gov (United States)

Fukuta, Masahiro; Kanamori, Satoshi; Furukawa, Taichi; Nawa, Yasunori; Inami, Wataru; Lin, Sheng; Kawata, Yoshimasa; Terakawa, Susumu

2015-01-01

Optical microscopes are effective tools for cellular function analysis because biological cells can be observed non-destructively and non-invasively in the living state in either water or atmosphere condition. Label-free optical imaging technique such as phase-contrast microscopy has been analysed many cellular functions, and it is essential technology for bioscience field. However, the diffraction limit of light makes it is difficult to image nano-structures in a label-free living cell, for example the endoplasmic reticulum, the Golgi body and the localization of proteins. Here we demonstrate the dynamic imaging of a label-free cell with high spatial resolution by using an electron beam excitation-assisted optical (EXA) microscope. We observed the dynamic movement of the nucleus and nano-scale granules in living cells with better than 100 nm spatial resolution and a signal-to-noise ratio (SNR) around 10. Our results contribute to the development of cellular function analysis and open up new bioscience applications. PMID:26525841

Dynamic nano-imaging of label-free living cells using electron beam excitation-assisted optical microscope.

Science.gov (United States)

Fukuta, Masahiro; Kanamori, Satoshi; Furukawa, Taichi; Nawa, Yasunori; Inami, Wataru; Lin, Sheng; Kawata, Yoshimasa; Terakawa, Susumu

2015-11-03

Optical microscopes are effective tools for cellular function analysis because biological cells can be observed non-destructively and non-invasively in the living state in either water or atmosphere condition. Label-free optical imaging technique such as phase-contrast microscopy has been analysed many cellular functions, and it is essential technology for bioscience field. However, the diffraction limit of light makes it is difficult to image nano-structures in a label-free living cell, for example the endoplasmic reticulum, the Golgi body and the localization of proteins. Here we demonstrate the dynamic imaging of a label-free cell with high spatial resolution by using an electron beam excitation-assisted optical (EXA) microscope. We observed the dynamic movement of the nucleus and nano-scale granules in living cells with better than 100 nm spatial resolution and a signal-to-noise ratio (SNR) around 10. Our results contribute to the development of cellular function analysis and open up new bioscience applications.

The emittance of high current heavy ion beams

International Nuclear Information System (INIS)

White, N.R.; Devaney, A.S.

1989-01-01

Ion implantation is the main application for high current heavy ion beams. Transfer ratio is defined as the ratio of the total ion current leaving the ion source to the current delivered to the endstation. This ratio is monitored and logged and its importance is explained. It is also affected by other factors, such as the isotopic and molecular composition of the total ion beam. The transfer ratio reveals the fraction of ions which are intercepted by parts of the beamline system. The effects of these ions are discussed in two categories: processing purity and reliability. In discussing the emittance of ribbon beams, the two orthogonal planes are usually considered separately. Longitudinal emittance is determined by slot length and by plasma ion temperature. It has already been revealed that the longitudinal divergence of the beams from BF3 is perhaps double that of the beam from arsenic vapour or argon, at the same total perveance from the ion source. This poses the question: why is the ion temperature higher for BF3 than for As or Ar? The transverse emittance is in practical terms dominated by the divergence. It is the most fruitful area for improvement in most real-world systems. There is an intrinsic divergence arising from initial ion energies within the plasma, and there is emittance growth that can occur as a result of aberration in the beam extraction optics. (N.K.)

Method for controlling low-energy high current density electron beams

International Nuclear Information System (INIS)

Lee, J.N.; Oswald, R.B. Jr.

1977-01-01

A method and an apparatus for controlling the angle of incidence of low-energy, high current density electron beams are disclosed. The apparatus includes a current generating diode arrangement with a mesh anode for producing a drifting electron beam. An auxiliary grounded screen electrode is placed between the anode and a target for controlling the average angle of incidence of electrons in the drifting electron beam. According to the method of the present invention, movement of the auxiliary screen electrode relative to the target and the anode permits reliable and reproducible adjustment of the average angle of incidence of the electrons in low energy, high current density relativistic electron beams

Visualisation of the high-current e-beams on solid surfaces

Energy Technology Data Exchange (ETDEWEB)

Solomonov, V I; Osipov, V V; Mikhajlov, S G; Lipchak, A I [Russian Academy of Sciences, Ural Division, Ekaterinburg (Russian Federation). Institute of Electrophysics

1997-12-31

Natural minerals such as spodumen, calcite, and Mn-doped apatite crystals may serve as suitable low-cost materials for visualization of high-current electron beams. High-intensity luminescence lasting several tens of minutes has been observed when irradiating natural specimen by electron beams with the current density of 10-1000 A/sq.cm, with energy of 100-300 keV, and pulse duration of 2-50 ns. The luminescent images of the beam cross-section provide information on the beam density profiles, while the images taken in the plane parallel to the beam axis make it possible to estimate the beam penetration depth and, therefore, the beam energy. The method is illustrated by examples of luminescent images taken from the experiment. (J.U.).

Direct nano-patterning of graphene with helium ion beams

International Nuclear Information System (INIS)

Naitou, Y.; Iijima, T.; Ogawa, S.

2015-01-01

Helium ion microscopy (HIM) was used for direct nano-patterning of single-layer graphene (SLG) on SiO 2 /Si substrates. This technique involves irradiation of the sample with accelerated helium ions (He + ). Doses of 2.0 × 10 16  He +  cm −2 from a 30 kV beam induced a metal-insulator transition in the SLG. The resolution of HIM patterning on SLG was investigated by fabricating nanoribbons and nanostructures. Analysis of scanning capacitance microscopy measurements revealed that the spatial resolution of HIM patterning depended on the dosage of He + in a non-monotonic fashion. Increasing the dose from 2.0 × 10 16 to 5.0 × 10 16  He +  cm −2 improved the spatial resolution to several tens of nanometers. However, doses greater than 1.0 × 10 17  He +  cm −2 degraded the patterning characteristics. Direct patterning using HIM is a versatile approach to graphene fabrication and can be applied to graphene-based devices

Isolation and characterization of cAMP-free and cAMP-bound forms of bovine heart type II cAMP-dependent protein kinase

International Nuclear Information System (INIS)

Cobb, C.E.

1986-01-01

Bovine heart type II cAMP-dependent protein kinase holoenzyme (cAMP-PK) was purified to homogeneity as determined by denaturing SDS-PAGE. An HPLC-DEAE purification step resolved two distinct peaks of cAMP-dependent kinase activity, which were designated Peak 1 and Peak 2 based on their order of elution. They had the same Stoke's radii and had very similar sedimentation coefficients. As determined by densitometric scanning of SDS-PAGE brands, by their mobility on denaturing PAGE, and by the ratios of equilibrium [ 3 H] cAMP binding to maximal kinase activity, the subunit stoichiometry of the two peaks was the same. In a cAMP assay it was found that Peak 1 holoenzyme was cAMP-free, but half of the Peak 2 holoenzyme cAMP binding sites contained cAMP. Dissociation assays indicated that the cAMP was equally distributed in binding Site 1 and Site 2 of Peak 2. Although SDS-PAGE analysis ruled out conversions by proteolysis or autophosphorylation-dephosphorylation, Peak 1 could be partially converted to Peak 2 by the addition of subsaturating amounts of cAMP, and Peak 2 could be partially converted to Peak 1 by aging. The interconvertibility of the two holoenzyme peaks strongly suggested that the difference between the two peaks was caused by the presence of cAMP in Peak 2

SU-E-T-391: Assessment and Elimination of the Angular Dependence of the Response of the NanoDot OSLD System in MV Beams

International Nuclear Information System (INIS)

Lehmann, J; Dunn, L; Lye, J; Kenny, J W; Alves, A D C; Cole, A; Asena, A; Kron, T; Williams, I M

2014-01-01

Purpose: Assess the angular dependence of the nanoDot OSLD system in MV X-ray beams at depths and mitigate this dependence for measurements in phantoms. Methods: Measurements for 6 MV photons at 3 cm and 10 cm depth and Monte Carlo simulations were performed. Two special holders were designed which allow a nanoDot dosimeter to be rotated around the center of its sensitive volume (5 mm diameter disk). The first holder positions the dosimeter disk perpendicular to the beam (en-face). It then rotates until the disk is parallel with the beam (edge on). This is referred to as Setup 1. The second holder positions the disk parallel to the beam (edge on) for all angles (Setup 2). Monte Carlo simulations using GEANT4 considered detector and housing in detail based on microCT data. Results: An average drop in response by 1.4±0.7% (measurement) and 2.1±0.3% (Monte Carlo) for the 90° orientation compared to 0° was found for Setup 1. Monte Carlo simulations also showed a strong dependence of the effect on the composition of the sensitive layer. Assuming 100% active material (Al??O??) results in a 7% drop in response for 90° compared to 0°. Assuming the layer to be completely water, results in a flat response (within simulation uncertainty of about 1%). For Setup 2, measurements and Monte Carlo simulations found the angular dependence of the dosimeter to be below 1% and within the measurement uncertainty. Conclusion: The nanoDot dosimeter system exhibits a small angular dependence off approximately 2%. Changing the orientation of the dosimeter so that a coplanar beam arrangement always hits the detector material edge on reduces the angular dependence to within the measurement uncertainty of about 1%. This makes the dosimeter more attractive for phantom based clinical measurements and audits with multiple coplanar beams. The Australian Clinical Dosimetry Service is a joint initiative between the Australian Department of Health and the Australian Radiation Protection and

Improvement of the 400 kV linac electron source of AmPS

International Nuclear Information System (INIS)

Kroes, F.B.; Beuzekom, M.G. van; Dobbe, N.J.; Es, J.T. van; Jansweijer, P.P.M.; Kruijer, A.H.; Luigjes, G.; Sluijk, T.G.B.

1992-01-01

An existing linac (MEA) injects electrons into the Amsterdam Pulse Stretcher (AmPS) ring. The linac's peak current increases from 20 to 80 mA. This requires the modification of the 400 kV low emittance gun. The fourfold increase of the peak current is obtained by doubling both the gun perveance (new gun part) and the pulsed extractor voltage. To obtain optimum beam quality over this increased current range, the hot deck electronics has been exchanged by a fast high voltage FET switching supply. A built-in microprocessor, coupled to the local computer by optical fibers, is used to monitor and control the gun parameters. The 5 kV gun extractor voltage pulse shape can be monitored by means of an analog fibre transducer with build in calibration. Finally, in order to improve the energy stability of the accelerated electrons, a serial electron-tube stabilizer was added to the 400 kV DC power supply. (K.A.) 4 refs.; 6 figs

Ion beams from high-current PF facilities

Energy Technology Data Exchange (ETDEWEB)

Sadowski, M [Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland)

1997-12-31

Pulsed beams of fast deuterons and impurity or admixture ions emitted from high-current PF-type facilities operated in different laboratories are dealt with. A short comparative analysis of time-integrated and time-resolved studies is presented. Particular attention is paid to the microstructure of such ion beams, and to the verification of some theoretical models. (author). 5 figs., 19 refs.

Development of capacitive beam position, beam current and Schottky-signal monitors for the Cryogenic Storage Ring (CSR)

International Nuclear Information System (INIS)

Laux, Felix

2011-01-01

In this thesis novel techniques based on capacitive pickups for the determination of the beam current, the beam position and the Schottky-signal in storage rings have been developed. Beam current measurements at the heavy ion storage ring TSR with a capacitive pickup have been found in very good agreement with the theory. Using this device the accurate measurement of beam currents at the TSR far below 1 μA is now possible. This method will also be used at the Cryogenic Storage Ring (CSR) at which beam currents in the range of 1 nA-1 μA are expected. For the first time, position measurements with a resonant amplifier system for capacitive pickups have been examined at the TSR for later use of this technique in the CSR. With this method an increased signal-to-noise ratio can be achieved using a parallel inductance. A comparison with measurements using the rest gas beam profile monitor has shown very good agreement even at very low intensities. Experiments with the cryo-capable electronics for the CSR beam position monitors have shown an achievable quality factor of Q=500, resulting in the prospect of precise position measurements at the CSR even at very low beam currents. The CSR Schottky-Pickup will also be equipped with a resonant amplifier system with a comparable quality factor. An estimation of the signal-to-noise ratio suggests a detection limit of a few protons. (orig.)

Large spin current injection in nano-pillar-based lateral spin valve

Energy Technology Data Exchange (ETDEWEB)

Nomura, Tatsuya [Department of Physics, Kyushu University, 744 Motooka, Fukuoka, 819-0395 (Japan); Ohnishi, Kohei; Kimura, Takashi, E-mail: t-kimu@phys.kyushu-u.ac.jp [Department of Physics, Kyushu University, 744 Motooka, Fukuoka, 819-0395 (Japan); Research Center for Quantum Nano-Spin Sciences, Kyushu University, 744 Motooka, Fukuoka, 819-0395 (Japan)

2016-08-26

We have investigated the influence of the injection of a large pure spin current on a magnetization process of a non-locally located ferromagnetic dot in nano-pillar-based lateral spin valves. Here, we prepared two kinds of the nano-pillar-type lateral spin valve based on Py nanodots and CoFeAl nanodots fabricated on a Cu film. In the Py/Cu lateral spin valve, although any significant change of the magnetization process of the Py nanodot has not been observed at room temperature. The magnetization reversal process is found to be modified by injecting a large pure spin current at 77 K. Switching the magnetization by the nonlocal spin injection has also been demonstrated at 77 K. In the CoFeAl/Cu lateral spin valve, a room temperature spin valve signal was strongly enhanced from the Py/Cu lateral spin valve because of the highly spin-polarized CoFeAl electrodes. The room temperature nonlocal switching has been demonstrated in the CoFeAl/Cu lateral spin valve.

Ion current reduction in pinched electron beam diodes

International Nuclear Information System (INIS)

Quintenz, J.P.; Poukey, J.W.

1977-01-01

A new version of a particle-in-cell diode code has been written which permits the accurate treatment of higher-current diodes with greater physical dimensions. Using this code, we have studied ways to reduce the ion current in large-aspect-ratio pinched electron beam diodes. In particular, we find that allowing the ions to reflex in such diodes lowers the ion to electron current ratio considerably. In a 3-MV R/d=24 case this ratio was lowered by a factor of 6--8 compared with the corresponding nonreflexing-ion diode, while still producing a superpinched electron beam

2′,3′-cAMP, 3′-AMP, and 2′-AMP inhibit human aortic and coronary vascular smooth muscle cell proliferation via A2B receptors

Science.gov (United States)

Ren, Jin; Gillespie, Delbert G.

2011-01-01

Rat vascular smooth muscle cells (VSMCs) from renal microvessels metabolize 2′,3′-cAMP to 2′-AMP and 3′-AMP, and these AMPs are converted to adenosine that inhibits microvascular VSMC proliferation via A2B receptors. The goal of this study was to test whether this mechanism also exists in VSMCs from conduit arteries and whether it is similarly expressed in human vs. rat VSMCs. Incubation of rat and human aortic VSMCs with 2′,3′-cAMP concentration-dependently increased levels of 2′-AMP and 3′-AMP in the medium, with a similar absolute increase in 2′-AMP vs. 3′-AMP. In contrast, in human coronary VSMCs, 2′,3′-cAMP increased 2′-AMP levels yet had little effect on 3′-AMP levels. In all cell types, 2′,3′-cAMP increased levels of adenosine, but not 5′-AMP, and 2′,3′-AMP inhibited cell proliferation. Antagonism of A2B receptors (MRS-1754), but not A1 (1,3-dipropyl-8-cyclopentylxanthine), A2A (SCH-58261), or A3 (VUF-5574) receptors, attenuated the antiproliferative effects of 2′,3′-cAMP. In all cell types, 2′-AMP, 3′-AMP, and 5′-AMP increased adenosine levels, and inhibition of ecto-5′-nucleotidase blocked this effect of 5′-AMP but not that of 2′-AMP nor 3′-AMP. Also, 2′-AMP, 3′-AMP, and 5′-AMP, like 2′,3′-cAMP, exerted antiproliferative effects that were abolished by antagonism of A2B receptors with MRS-1754. In conclusion, VSMCs from conduit arteries metabolize 2′,3′-cAMP to AMPs, which are metabolized to adenosine. In rat and human aortic VSMCs, both 2′-AMP and 3′-AMP are involved in this process, whereas, in human coronary VSMCs, 2′,3′-cAMP is mainly converted to 2′-AMP. Because adenosine inhibits VSMC proliferation via A2B receptors, local vascular production of 2′,3′-cAMP may protect conduit arteries from atherosclerosis. PMID:21622827

Effect of high energy electron beam (10 MeV) on specific heat capacity of low-density polyethylene/hydroxyapatite nano-composite

Energy Technology Data Exchange (ETDEWEB)

Soltani, Z., E-mail: zhr_soltani@yahoo.com [Health Physics and Radiation Dosimetry Research Laboratory, Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Ziaie, F. [Radiation Application Research School, Nuclear Science & Technology Research Institute, Tehran (Iran, Islamic Republic of); Ghaffari, M. [Polymer Group, Golestan University, Golestan (Iran, Islamic Republic of); Beigzadeh, A.M. [Radiation Application Research School, Nuclear Science & Technology Research Institute, Tehran (Iran, Islamic Republic of)

2017-02-01

In the present work, thermal properties of low density polyethylene (LDPE) and its nano composites are investigated. For this purpose LDPE reinforced with different weight percents of hydroxyapatite (HAP) powder which was synthesized via hydrolysis method are produced. The samples were irradiated with 10 MeV electron beam at doses of 75 to 250 kGy. Specific heat capacity measurement have been carried out at different temperatures, i.e. 25, 50, 75 and 100 °C using modulated temperature differential scanning calorimetry (MTDSC) apparatus and the effect of three parameters include of temperature, irradiation dose and the amount of HAP nano particles as additives on the specific heat capacity of PE/HAP have been investigated precisely. The MTDSC results indicate that the specific heat capacity have decreased by addition of nano sized HAP as reinforcement for LDPE. On the other hand, the effect of radiation dose is reduction in the specific heat capacity in all materials including LDPE and its nano composites. The HAP nano particles along with cross-link junctions due to radiation restrain the movement of the polymer chains in the vicinity of each particle and improve the immobility of polymer chains and consequently lead to reduction in specific heat capacity. Also, the obtained results confirm that the radiation effect on the specific heat capacity is more efficient than the reinforcing effect of nano-sized hydroxyapatite.

Generation and transportation of low-energy, high-current electron beams

International Nuclear Information System (INIS)

Ozur, G.E.; Proskurovskij, D.I.; Nazarov, D.S.

1996-01-01

Experimental data on the production of low-energy, high-current electron beams in a plasma-filled diode are presented. The highest beam energy density achieved is about 40 J/cm 2 , which makes it possible to treat materials in the mode of intense evaporation of the surface layer. It was shown that the use of a hollow cathode improves the beam homogeneity. The feasibility was demonstrated of the production of low-energy high-current electron beams in a gun with plasma anode based on the use of a reflective discharge. (author). 6 figs., 6 refs

Recent Advances in the Development of Antimicrobial Peptides (AMPs): Attempts for Sustainable Medicine?

Science.gov (United States)

Kokel, Anne; Torok, Marianna

2018-01-17

Since the first isolation of antimicrobial peptides (AMPs) they have attracted extensive interest in medicinal chemistry. However, only a few AMP-based drugs are currently available on the market. Despite their effectiveness, biodegradability, and versatile mode of action that is less likely to induce resistance compared to conventional antibiotics, AMPs suffer from major issues that need to be addressed to broaden their use. Notably, AMPs can lack selectivity leading to side effects and cytotoxicity, and also exhibit in vivo instability. Several strategies are being actively considered to overcome the limitations that restrain the success of AMPs. In the current work, recent strategies reported for improving AMPs in the context of drug design and delivery were surveyed, and also their possible impact on patients and the environment was assessed. As a major advantage AMPs possess an easily tunable skeleton offering opportunities to improve their properties. Strategic structural modifications and the beneficial properties of cyclic or branched AMPs in term of stability have been reported. The conjugation of AMPs with nanoparticles has also been explored to increase their in vivo stability. Other techniques such as the coupling of AMPs with specific antibodies aim to increase the selectivity of the potential drug towards the target. These strategies were evaluated for their effect on the environment highlighting green technologies. Although further research is needed taking into account both environmental and human health consequences of novel AMPs several of these compounds are promising drug candidates for use in sustainable medicine. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

[Physiopathology of cAMP/PKA signaling in neurons].

Science.gov (United States)

Castro, Liliana; Yapo, Cedric; Vincent, Pierre

2016-01-01

Cyclic adenosine monophosphate (cAMP) and the cyclic-AMP dependent protein kinase (PKA) regulate a plethora of cellular functions in virtually all eukaryotic cells. In neurons, the cAMP/PKA signaling cascade controls a number of biological properties such as axonal growth, synaptic transmission, regulation of excitability or long term changes in the nucleus. Genetically-encoded optical biosensors for cAMP or PKA considerably improved our understanding of these processes by providing a real-time measurement in living neurons. In this review, we describe the recent progresses made in the creation of biosensors for cAMP or PKA activity. These biosensors revealed profound differences in the amplitude of the cAMP signal evoked by neuromodulators between various neuronal preparations. These responses can be resolved at the level of individual neurons, also revealing differences related to the neuronal type. At the subcellular level, biosensors reported different signal dynamics in domains like dendrites, cell body, nucleus and axon. Combining this imaging approach with pharmacology or genetical models points at phosphodiesterases and phosphatases as critical regulatory proteins. Biosensor imaging will certainly help understand the mechanism of action of current drugs as well as help in devising novel therapeutic strategies for neuropsychiatric diseases. © Société de Biologie, 2017.

Beam current monitors at the UNILAC

International Nuclear Information System (INIS)

Schneider, N.

1998-01-01

One of the most basic linac operation tools is a beam current transformer. Using outstanding materials, the latest low-noise amplifiers, and some good ideas, a universal current monitoring system has been developed and installed at the UNILAC at GSI. With a dynamic range of 112 dB, covering the low-current range down to 100 nA peak to peak at S/N=1, as well as 25 mA pulses, provided for high-current injection to the SIS synchrotron, a well-accepted diagnostic instrument could be placed at the disposal of the operaters

Polymer/Layered Silicate Nano composites

International Nuclear Information System (INIS)

Bakhit, M.E.E.H.

2012-01-01

Polymer–clay nano composites have attracted the attention of many researchers and experimental results are presented in a large number of recent papers and patents because of the outstanding mechanical properties and low gas permeabilities that are achieved in many cases. Polymer-clay nano composites are a new class of mineral-field polymer that contain relatively small amounts (<10%) of nanometer-sized clay particles. Polymer/clay nano composites have their origin in the pioneering research conducted at Toyota Central Research Laboratories and the first historical record goes back to 1987. The matrix was nylon-6 and the filler MMT. Because of its many advantages such as high mechanical properties, good gas barrier, flame retardation, etc. polymer/clay nano composites have been intensely investigated and is currently the subject of many research programs. Nano composite materials are commercially important and several types of products with different shapes and applications including food packaging films and containers, engine parts, dental materials, etc. are now available in markets. A number of synthesis routes have been developed in the recent years to prepare these materials, which include intercalation of polymers or prepolymers from solution, in-situ polymerization, melt intercalation etc. In this study, new nano composite materials were produced from the components of rubber (Nbr, SBR and EPDM) as the polymeric matrix and organically modified quaternary alkylammonium montmorillonite in different contents (3, 5, 7, and 10 phr) as the filler by using an extruder then, the rubber nano composite sheets were irradiated at a dose of 0, 50, 75, 100 and 150 KGy using Electron beam Irradiation technique as a crosslinking agent. These new materials can be characterized by using various analytical techniques including X-ray diffractometer XRD, Thermogravimetric analyzer TGA, scanning electron microscope (SEM), transmission electron microscope (TEM),Fourier transform

Gamma and neutron irradiation tests on commercial IC op amps

International Nuclear Information System (INIS)

Kennedy, E.J.; Morris, A.C. Jr.; Su, D.K.

1985-01-01

Experimental results of gamma and neutron irradiation tests on 30 types of integrated-circuit operational amplifiers from 11 manufacturers are presented. All units were low-cost, commercial-grade devices. Op amps were evaluated for changes in offset voltage, input bias current, power supply current, open-loop gain, gain-bandwidth product, slew rate, power-supply and common-mode rejection ratios. Bipolar transistor op amps with resistive collector load resistors for the input stage indicated the best radiation hardness

Anoctamin 9/TMEM16J is a cation channel activated by cAMP/PKA signal.

Science.gov (United States)

Kim, Hyungsup; Kim, Hyesu; Lee, Jesun; Lee, Byeongjun; Kim, Hee-Ryang; Jung, Jooyoung; Lee, Mi-Ock; Oh, Uhtaek

2018-05-01

Anoctamins (ANOs) are multifunctional membrane proteins that consist of 10 homologs. ANO1 (TMEM16A) and ANO2 (TMEM16B) are anion channels activated by intracellular calcium that meditate numerous physiological functions. ANO6 is a scramblase that redistributes phospholipids across the cell membrane. The other homologs are not well characterized. We found ANO9/TMEM16J is a cation channel activated by a cAMP-dependent protein kinase A (PKA). Intracellular cAMP-activated robust currents in whole cells expressing ANO9, which were inhibited by a PKA blocker. A cholera toxin that persistently stimulated adenylate cyclase activated ANO9 as did the application of PKA. The cAMP-induced ANO9 currents were permeable to cations. The cAMP-dependent ANO9 currents were augmented by intracellular Ca 2+ . Ano9 transcripts were predominant in the intestines. Human intestinal SW480 cells expressed high levels of Ano9 transcripts and showed PKA inhibitor-reversible cAMP-dependent currents. We conclude that ANO9 is a cation channel activated by a cAMP/PKA pathway and could play a role in intestine function. Copyright © 2017. Published by Elsevier Ltd.

Structural Design of a Compact in-Plane Nano-Grating Accelerometer

International Nuclear Information System (INIS)

Yao Bao-Yin; Zhou Zhen; Feng Li-Shuang; Wang Wen-Pu; Wang Xiao

2012-01-01

A combination of large mass, weak spring and nano-grating is the key for a nano-grating accelerometer to measure nano-G acceleration. A novel compact nano-grating accelerometer integrating a large mass with nano-grating is proposed. First, the numbers of diffraction orders are calculated. Then, structure parameters are optimized by finite element analysis to achieve a high sensitivity in an ideal vibration mode. Finally, we design the fabrication method to form such a compact nano-grating accelerometer and successfully fabricate the uniform and well-designed nano-gratings with a period of 847 nm, crater of 451 nm by an FIB/SEM dual beam system. Based on the ANSYS simulation, a nano-grating accelerometer is predicted to work in the first modal and enables the accelerometer to have displacement sensitivity at 197 nm/G with a measurement range of ±1 G, corresponding to zeroth diffraction beam optical sensitivity 1%/mG. The nano-gratings fabricated are very close to those designed ones within experimental error to lay the foundation for the sequent fabrication. These results provide a theoretical basis for the design and fabrication of nano-grating accelerometers

Propagation of high-current fast electron beam in a dielectric target

International Nuclear Information System (INIS)

Klimo, O.; Debayle, A.; Tikhonchuk, V.T.

2006-01-01

Complete test of publication follows. A relativistic electron beam with very high current density may be produced during the interaction of a short high intensity laser pulse with a solid target. In Fast Ignition approach to Inertial Confinement Fusion, such beam is supposed to heat a part of the precompressed DT fuel pellet to the conditions of an efficient ignition. For successful implementation of Fast Ignition understanding the propagation and energy deposition of the beam is crucial. A number of processes, mostly associated with the return current, are dissipating the energy of the beam or inhibiting its collimated transport, namely the filamentation. Weibel, two-stream or the recently proposed ionization instability. Ionization instability may develop in a solid dielectric target due to the dependence of the propagation velocity of the beam on the beam density. To study the propagation of high current electron beam in dielectric target, we use a one-dimensional relativistic electrostatic simulation code based on the Particle in Cell method. The code includes ionization processes in dielectric material and collisions of newly generated cold electrons. The current density of the relativistic electron beam used in this work is in the range 3-300 GA/cm 2 , while its length roughly corresponds to the beam, produced by a 40 fs laser pulse. Propagation of the beam in the polyethylene target is studied. The code is complemented by an analytical model, which is applicable og a wider range of beam parameters that are currently beyond our computational possibilities. When the head of the beam enters the plastic target, electric field grows rapidly in consequence of the charge separation and it starts to ionize atoms. In the maximum of the field, which is less than 10% of the atomic field, the density of new free electrons is two orders of magnitude higher than the beam density, which is enough for the current neutralization. Cold electrons are accelerated by the field

The Impact of Beam Deposition on Bootstrap Current of Fast Ion Produced by Neutral Beam Tangential Injection

International Nuclear Information System (INIS)

Huang Qian-Hong; Gong Xue-Yu; Lu Xing-Qiang; Yu Jun; Cao Jin-Jia

2015-01-01

The density profile of fast ions arising from a tangentially injected diffuse neutral beam in tokamak plasma is calculated. The effects of mean free paths and beam tangency radius on the density profile are discussed under typical HL-2A plasmas parameters. The results show that the profile of fast ions is strongly peaked at the center of the plasma when the mean free path at the maximum deuteron density is larger than the minor radius, while the peak value decreases when the mean free path at the maximum deuteron density is larger than twice that of the minor radius due to the beam transmission loss. Moreover, the bootstrap current of fast ions for various mean free paths at the maximum deuteron density is calculated and its density is proved to be closely related to the deposition of the neutral beam. With the electron return current considered, the net current density obviously decreases. Meanwhile, the peak central fast ion density increases when the beam tangency radius approaches the major radius, and the net bootstrap current increases rapidly with the increasing beam tangency radius. (paper)

Generation and transportation of low-energy, high-current electron beams

Energy Technology Data Exchange (ETDEWEB)

Ozur, G E; Proskurovskij, D I; Nazarov, D S [Russian Academy of Sciences, Tomsk (Russian Federation). Institute of High Current Electronics

1997-12-31

Experimental data on the production of low-energy, high-current electron beams in a plasma-filled diode are presented. The highest beam energy density achieved is about 40 J/cm{sup 2}, which makes it possible to treat materials in the mode of intense evaporation of the surface layer. It was shown that the use of a hollow cathode improves the beam homogeneity. The feasibility was demonstrated of the production of low-energy high-current electron beams in a gun with plasma anode based on the use of a reflective discharge. (author). 6 figs., 6 refs.

Resistance and sheet resistance measurements using electron beam induced current

International Nuclear Information System (INIS)

Czerwinski, A.; Pluska, M.; Ratajczak, J.; Szerling, A.; KaPtcki, J.

2006-01-01

A method for measurement of spatially uniform or nonuniform resistance in layers and strips, based on electron beam induced current (EBIC) technique, is described. High electron beam currents are used so that the overall resistance of the measurement circuit affects the EBIC signal. During the evaluation, the electron beam is scanned along the measured object, whose load resistance varies with the distance. The variation is compensated by an adjustable resistance within an external circuit. The method has been experimentally deployed for sheet resistance determination of buried regions of lateral confinements in semiconductor laser heterostructures manufactured by molecular beam epitaxy

Particle-in-cell simulations of electron beam control using an inductive current divider

Energy Technology Data Exchange (ETDEWEB)

Swanekamp, S. B.; Angus, J. R.; Cooperstein, G.; Ottinger, P. F.; Richardson, A. S.; Schumer, J. W.; Weber, B. V. [Plasma Physics Division, Naval Research Laboratory, Washington, District of Columbia 20375 (United States)

2015-11-15

Kinetic, time-dependent, electromagnetic, particle-in-cell simulations of the inductive current divider are presented. The inductive current divider is a passive method for controlling the trajectory of an intense, hollow electron beam using a vacuum structure that inductively splits the beam's return current. The current divider concept was proposed and studied theoretically in a previous publication [Swanekamp et al., Phys. Plasmas 22, 023107 (2015)]. A central post carries a portion of the return current (I{sub 1}), while the outer conductor carries the remainder (I{sub 2}) with the injected beam current given by I{sub b} = I{sub 1} + I{sub 2}. The simulations are in agreement with the theory which predicts that the total force on the beam trajectory is proportional to (I{sub 2}−I{sub 1}) and the force on the beam envelope is proportional to I{sub b}. Independent control over both the current density and the beam angle at the target is possible by choosing the appropriate current-divider geometry. The root-mean-square (RMS) beam emittance (ε{sub RMS}) varies as the beam propagates through the current divider to the target. For applications where control of the beam trajectory is desired and the current density at the target is similar to the current density at the entrance foil, there is a modest 20% increase in ε{sub RMS} at the target. For other applications where the beam is pinched to a current density ∼5 times larger at the target, ε{sub RMS} is 2–3 times larger at the target.

An accurate low current measurement circuit for heavy iron beam current monitor

International Nuclear Information System (INIS)

Zhou Chaoyang; Su Hong; Mao Ruishi; Dong Chengfu; Qian Yi; Kong Jie

2012-01-01

Heavy-ion beams at 10 6 particles per second have been applied to the treatment of deep-seated inoperable tumors in the therapy terminal of the Heavy Ion Research Facility in Lanzhou (HIRFL) which is located at the Institute of Modern Physics, Chinese Academy of Sciences (IMP, CAS). An accurate low current measurement circuit following a Faraday cup was developed to monitor the beam current at pA range. The circuit consisted of a picoammeter with a bandwidth of 1 kHz and a gated integrator (GI). A low input bias current precision amplifier and new guarding and shielding techniques were used in the picoammeter circuit which allowed as to measure current less than 1 pA with a current gain of 0.22 V/pA and noise less than 10 fA. This paper will also describe a novel compensation approach which reduced the charge injection from switches in the GI to 10 −18 C, and a T-switch configuration which was used to eliminate leakage current in the reset switch.

Collisionless effects on beam-return current systems in solar flares

Science.gov (United States)

Vlahos, L.; Rowland, H. L.

1985-01-01

A theoretical study of the beam-return current system (BRCS) in solar flares shows that the precipitating electrons modify the way in which the return current (RC) is carried by the background plasma. In particular it is found that the RC is not carried by the bulk of the electrons but by a small number of high-velocity electrons. For beam/plasma densities exceeding approximately 0.001, this can reduce the effects of collisions and heating by the RC. For higher-density beams, where the RC could be unstable to current-driven instabilities, the effects of strong turbulence anomalous resistivity prevent the appearance of such instabilities. The main conclusion is that the BRCS is interconnected, and that the beam-generated strong turbulence determines how the RC is carried.

AMP Deaminase 3 Deficiency Enhanced 5′-AMP Induction of Hypometabolism

Science.gov (United States)

Daniels, Isadora Susan; O′Brien, William G.; Nath, Vinay; Zhao, Zhaoyang; Lee, Cheng Chi

2013-01-01

A hypometabolic state can be induced in mice by 5′-AMP administration. Previously we proposed that an underlying mechanism for this hypometabolism is linked to reduced erythrocyte oxygen transport function due to 5′-AMP uptake altering the cellular adenylate equilibrium. To test this hypothesis, we generated mice deficient in adenosine monophosphate deaminase 3 (AMPD3), the key catabolic enzyme for 5′-AMP in erythrocytes. Mice deficient in AMPD3 maintained AMPD activities in all tissues except erythrocytes. Developmentally and morphologically, the Ampd3−/− mice were indistinguishable from their wild type siblings. The levels of ATP, ADP but not 5′-AMP in erythrocytes of Ampd3−/− mice were significantly elevated. Fasting blood glucose levels of the Ampd3−/− mice were comparable to wild type siblings. In comparison to wild type mice, the Ampd3−/− mice displayed a deeper hypometabolism with a significantly delayed average arousal time in response to 5′-AMP administration. Together, these findings demonstrate a central role of AMPD3 in the regulation of 5′-AMP mediated hypometabolism and further implicate erythrocytes in this behavioral response. PMID:24066180

High-current beam dynamics and transport, theory and experiment

International Nuclear Information System (INIS)

Reiser, M.

1986-01-01

Recent progress in the understanding of beam physics and technology factors determining the current and brightness of ion and electron beams in linear accelerators will be reviewed. Topics to be discussed including phase-space density constraints of particle sources, low-energy beam transport include charge neutralization, emittance growth due to mismatch, energy exchange, instabilities, nonlinear effects, and longitudinal bunching

Direct nano-patterning of graphene with helium ion beams

Energy Technology Data Exchange (ETDEWEB)

Naitou, Y., E-mail: yu-naitou@aist.go.jp [Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8562 (Japan); Iijima, T.; Ogawa, S. [Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba 305-8569 (Japan)

2015-01-19

Helium ion microscopy (HIM) was used for direct nano-patterning of single-layer graphene (SLG) on SiO{sub 2}/Si substrates. This technique involves irradiation of the sample with accelerated helium ions (He{sup +}). Doses of 2.0 × 10{sup 16 }He{sup + }cm{sup −2} from a 30 kV beam induced a metal-insulator transition in the SLG. The resolution of HIM patterning on SLG was investigated by fabricating nanoribbons and nanostructures. Analysis of scanning capacitance microscopy measurements revealed that the spatial resolution of HIM patterning depended on the dosage of He{sup +} in a non-monotonic fashion. Increasing the dose from 2.0 × 10{sup 16} to 5.0 × 10{sup 16 }He{sup + }cm{sup −2} improved the spatial resolution to several tens of nanometers. However, doses greater than 1.0 × 10{sup 17 }He{sup + }cm{sup −2} degraded the patterning characteristics. Direct patterning using HIM is a versatile approach to graphene fabrication and can be applied to graphene-based devices.

2',3'-cAMP, 3'-AMP, 2'-AMP and adenosine inhibit TNF-α and CXCL10 production from activated primary murine microglia via A2A receptors.

Science.gov (United States)

Newell, Elizabeth A; Exo, Jennifer L; Verrier, Jonathan D; Jackson, Travis C; Gillespie, Delbert G; Janesko-Feldman, Keri; Kochanek, Patrick M; Jackson, Edwin K

2015-01-12

Some cells, tissues and organs release 2',3'-cAMP (a positional isomer of 3',5'-cAMP) and convert extracellular 2',3'-cAMP to 2'-AMP plus 3'-AMP and convert these AMPs to adenosine (called the extracellular 2',3'-cAMP-adenosine pathway). Recent studies show that microglia have an extracellular 2',3'-cAMP-adenosine pathway. The goal of the present study was to investigate whether the extracellular 2',3'-cAMP-adenosine pathway could have functional consequences on the production of cytokines/chemokines by activated microglia. Experiments were conducted in cultures of primary murine microglia. In the first experiment, the effect of 2',3'-cAMP, 3'-AMP, 2'-AMP and adenosine on LPS-induced TNF-α and CXCL10 production was determined. In the next experiment, the first protocol was replicated but with the addition of 1,3-dipropyl-8-p-sulfophenylxanthine (DPSPX) (0.1 μM; antagonist of adenosine receptors). The last experiment compared the ability of 2-chloro-N(6)-cyclopentyladenosine (CCPA) (10 μM; selective A1 agonist), 5'-N-ethylcarboxamide adenosine (NECA) (10 μM; agonist for all adenosine receptor subtypes) and CGS21680 (10 μM; selective A2A agonist) to inhibit LPS-induced TNF-α and CXCL10 production. (1) 2',3'-cAMP, 3'-AMP, 2'-AMP and adenosine similarly inhibited LPS-induced TNF-α and CXCL10 production; (2) DPSPX nearly eliminated the inhibitory effects of 2',3'-cAMP, 3'-AMP, 2'-AMP and adenosine on LPS-induced TNF-α and CXCL10 production; (3) CCPA did not affect LPS-induced TNF-α and CXCL10; (4) NECA and CGS21680 similarly inhibited LPS-induced TNF-α and CXCL10 production. 2',3'-cAMP and its metabolites (3'-AMP, 2'-AMP and adenosine) inhibit LPS-induced TNF-α and CXCL10 production via A2A-receptor activation. Adenosine and its precursors, via A2A receptors, likely suppress TNF-α and CXCL10 production by activated microglia in brain diseases. Copyright © 2014 Elsevier B.V. All rights reserved.

High current precision long pulse electron beam position monitor

CERN Document Server

Nelson, S D; Fessenden, T J; Holmes, C

2000-01-01

Precision high current long pulse electron beam position monitoring has typically experienced problems with high Q sensors, sensors damped to the point of lack of precision, or sensors that interact substantially with any beam halo thus obscuring the desired signal. As part of the effort to develop a multi-axis electron beam transport system using transverse electromagnetic stripline kicker technology, it is necessary to precisely determine the position and extent of long high energy beams for accurate beam position control (6 - 40 MeV, 1 - 4 kA, 2 μs beam pulse, sub millimeter beam position accuracy.) The kicker positioning system utilizes shot-to-shot adjustments for reduction of relatively slow (< 20 MHz) motion of the beam centroid. The electron beams passing through the diagnostic systems have the potential for large halo effects that tend to corrupt position measurements.

RADLAC II high current electron beam propagation experiment

International Nuclear Information System (INIS)

Frost, C.A.; Shope, S.L.; Mazarakis, M.G.; Poukey, J.W.; Wagner, J.S.; Turman, B.N.; Crist, C.E.; Welch, D.R.; Struve, K.W.

1993-01-01

The resistive hose instability of an electron beam was observed to be convective in recent RADLAC II experiments for higher current shots. The effects of air scattering for these shots were minimal. These experiments and theory suggest low-frequency hose motion which does not appear convective may be due to rapid expansion and subsequent drifting of the beam nose

Charged particle beam current monitoring tutorial

International Nuclear Information System (INIS)

Webber, R.C.

1994-10-01

A tutorial presentation is made on topics related to the measurement of charged particle beam currents. The fundamental physics of electricity and magnetism pertinent to the problem is reviewed. The physics is presented with a stress on its interpretation from an electrical circuit theory point of view. The operation of devices including video pulse current transformers, direct current transformers, and gigahertz bandwidth wall current style transformers is described. Design examples are given for each of these types of devices. Sensitivity, frequency response, and physical environment are typical parameters which influence the design of these instruments in any particular application. Practical engineering considerations, potential pitfalls, and performance limitations are discussed

Slice of the LHC prototype beam tubes in dipole magnet

CERN Multimedia

1995-01-01

A slice of the LHC accelerator prototype beam tubes surrounded by magnets. The LHC will accelerate two proton beams in opposite directions. The high bending and accelerating fields needed can only be reached using superconductors. At very low temperatures superconductors have no electrical resistance and therefore no power loss. The LHC will be the largest superconducting installation ever built, a unique challenge for CERN and its industrial partners. About dipole magnets: There will be 1232 dipole magnets in the LHC, used to guide the particles around the 27 km ring. Dipole magnets must have an extremely uniform field, which means the current flowing in the coils has to be very precisely controlled. Nowhere before has such precision been achieved at such high currents. The temperature is measured to five thousandths of a degree, the current to one part in a million. The current creating the magnetic field will pass through superconducting wires at up to 12 500 amps, about 30 000 times the current flowing ...

Electron-beam-induced welding of 3D nano-objects from beneath

International Nuclear Information System (INIS)

Moskalenko, A V; Burbridge, D J; Viau, G; Gordeev, S N

2007-01-01

Exposure of a sample to the electron beam in a scanning electron microscope (SEM) results in the growth of a film of amorphous carbon due to decomposition of hydrocarbon molecules, which are always present in small quantities in the SEM chamber. This growth is induced mainly by secondary electrons backscattered by atoms of both the sample and substrate. We show that, because the secondary electrons are spread beyond the exposed area, this deposit can be grown in areas of geometric shadow and therefore can be used for bonding of different complex 3D nano-objects to a substrate. This is demonstrated by welding 100 nm Fe-Co-Ni nanoparticles to the surface of 2D graphite. The tip of an atomic force microscope was used to probe the mechanical properties of the formed nanostructures. We observed that, for layers thicker than 25 nm, the nanoparticle is bonded so strongly that it is easier to break the particle than to separate it from the substrate

Improvement of the 400 kV linac electron source of AmPS

International Nuclear Information System (INIS)

Kroes, F.B.; Beuzekom, M.G. van; Dobbe, N.J.; Es, J.T. van; Jansweijer, P.P.M.; Kruijer, A.H.; Luigjes, G.; Sluijk, T.G.B.

1992-01-01

The installation of the 900 MeV Amsterdam Pulse Stretcher is nearly completed and its commissioning will start Spring 1992. The existing linac MEA will inject electrons in the AmPS ring. The linacs peak current will be increased from 20 to 80 mA. This requires modification of the 400 kV low emittance gun which now will deliver a peak current of maximum 400 mA instead of 100 mA at a pulse width of 2.1 μsec. The fourfold increase of the peakcurrent is obtained by doubling both the gun perveance (new gun part) and the pulsed extractor voltage. After chopping and pre-bunching more than 80 mA will be available for acceleration in MEA. To obtain optimum beam quality over this increased current range the hot deck electronics, operating at -400 kV, has been exchanged by a state of the art fast high voltage FET switching supply. The increased space charge forces in the beam require stronger electro-static focusing in the first electrostatic gap to define the beam diameter at the gun exit. This is accomplished with a 25 kV controlled power supply. A build in microprocessor, coupled to the local computer by optical fibers, is used to monitor and control the gun parameters. The 5kV gun extractor voltage pulse shape can be monitored by means of an analog fibre transducer with build in calibration. Finally, in order to improve the energy stability of the accelerated electrons a serial electron-tube stabilizer was added to the 400 kV DC power supply. A supply stability of 2. 10 -5 has been achieved. (author). 4 refs.; 6 figs

Surface composite nanostructures of AZ91 magnesium alloy induced by high current pulsed electron beam treatment

International Nuclear Information System (INIS)

Li, M.C.; Hao, S.Z.; Wen, H.; Huang, R.F.

2014-01-01

High current pulsed electron beam (HCPEB) treatment was conducted on an AZ91 cast magnesium alloy with accelerating voltage 27 kV, energy density 3 J/cm 2 and pulse duration 2.5 μs. The surface microstructure was characterized by optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS), and transmission electron microscope (TEM). The surface corrosion property was tested with electrochemical method in 3.5 wt.% NaCl solution. It is found that after 1 pulse of HCPEB treatment, the initial eutectic α phase and Mg 17 Al 12 particles started to dissolve in the surface modified layer of depth ∼15 μm. When using 15 HCPEB pulses, the Al content in surface layer increased noticeably, and the phase structure was modified as composite nanostructures consisted of nano-grained Mg 3.1 Al 0.9 domains surrounded by network of Mg 17 Al 12 phase. The HCPEB treated samples showed an improved corrosion resistance with cathodic current density decreased by two orders of magnitude as compared to the initial AZ91 alloy.

Current induced multi-mode propagating spin waves in a spin transfer torque nano-contact with strong perpendicular magnetic anisotropy

Science.gov (United States)

Mohseni, S. Morteza; Yazdi, H. F.; Hamdi, M.; Brächer, T.; Mohseni, S. Majid

2018-03-01

Current induced spin wave excitations in spin transfer torque nano-contacts are known as a promising way to generate exchange-dominated spin waves at the nano-scale. It has been shown that when these systems are magnetized in the film plane, broken spatial symmetry of the field around the nano-contact induced by the Oersted field opens the possibility for spin wave mode co-existence including a non-linear self-localized spin-wave bullet and a propagating mode. By means of micromagnetic simulations, here we show that in systems with strong perpendicular magnetic anisotropy (PMA) in the free layer, two propagating spin wave modes with different frequency and spatial distribution can be excited simultaneously. Our results indicate that in-plane magnetized spin transfer nano-contacts in PMA materials do not host a solitonic self-localized spin-wave bullet, which is different from previous studies for systems with in plane magnetic anisotropy. This feature renders them interesting for nano-scale magnonic waveguides and crystals since magnon transport can be configured by tuning the applied current.

Achromatic beam transport of High Current Injector

International Nuclear Information System (INIS)

Kumar, Sarvesh; Mandal, A.

2016-01-01

The high current injector (HCI) provides intense ion beams of high charge state using a high temperature superconducting ECR ion source. The ion beam is accelerated upto a final energy of 1.8 MeV/u due to an electrostatic potential, a radio frequency quadrupole (RFQ) and a drift tube linac (DTL). The ion beam has to be transported to superconducting LINAC which is around 50 m away from DTL. This section is termed as high energy beam transport section (HEBT) and is used to match the beam both in transverse and longitudinal phase space to the entrance of LINAC. The HEBT section is made up of four 90 deg. achromatic bends and interconnecting magnetic quadrupole triplets. Two RF bunchers have been used for longitudinal phase matching to the LINAC. The ion optical design of HEBT section has been simulated using different beam dynamics codes like TRACEWIN, GICOSY and TRACE 3D. The field computation code OPERA 3D has been utilized for hardware design of all the magnets. All the dipole and quadrupole magnets have been field mapped and their test results such as edge angles measurements, homogeneity and harmonic analysis etc. are reported. The whole design of HEBT section has been performed such that the most of the beam optical components share same hardware design and there is ample space for beam diagnostics as per geometry of the building. Many combination of achromatic bends have been simulated to transport the beam in HEBT section but finally the four 90 deg. achromatic bend configuration is found to be the best satisfying all the geometrical constraints with simplified beam tuning process in real time

A squid-based beam current monitor for FAIR/CRYRING

International Nuclear Information System (INIS)

Geithner, Rene; Stöhlker, Thomas; Kurian, Febin; Reeg, Hansjörg; Schwickert, Marcus; Neubert, Ralf; Seidel, Paul

2015-01-01

A SQUID-based beam current monitor was developed for the upcoming FAIR-Project, providing a non-destructive online monitoring of the beam currents in the nA-range. The cryogenic current comparator (CCC) was optimized for lowest possible noise-limited current resolution together with a high system bandwidth. This CCC is foreseen to be installed in the CRYRING facility (CRYRING@ESR: A study group report www.gsi.de/fileadmin/SPARC/documents/Cryring/ReportCryring-40ESR.PDF), working as a test bench for FAIR. In this contribution we present results of the completed CCC for FAIR/CRYRING and also arrangements that have been done for the installation of the CCC at CRYRING, regarding the cryostat design. (paper)

Design and initial tests of beam current monitoring systems for the APS transport lines

International Nuclear Information System (INIS)

Wang, Xucheng.

1992-01-01

The non-intercepting beam current monitoring systems suitable for a wide, range of beam parameters have been developed for the Advanced Photon Source (APS) low energy transport lines and high energy transport line. The positron or electron beam pulse in the transport lines wig have peak beam currents ranging from 8 mA to 29 A with pulse widths varying from 120 ps to 30 ns and pulse repetition rates from 2 Hz to 60 Hz. The peak beam current or total beam charge is measured with the fast or integrating current transformer, respectively, manufactured by Bergoz. In-house high speed beam signal processing electronics provide a DC level output proportional to the peak current or total charge for the digitizer input. The prototype systems were tested on the linacs which have beam pulse structures similar to that of the APS transport lines. This paper describes the design of beam signal processing electronics and grounding and shielding methods for current transformers. The results of the initial operations are presented. A short introduction on the preliminary design of current monitoring systems for the APS rings is also included

Multi-beam injector development at LBL

International Nuclear Information System (INIS)

Rutkowski, H.L.; Faltens, A.; Brodzik, D.A.; Johnson, R.M.; Pike, C.D.; Vanecek, D.L.; Humphries, S. Jr.; Meyer, E.A.; Hewett, D.W.

1990-06-01

LBL is developing a multi-beam injector that will be used for scaled accelerator experiments related to Heavy Ion Fusion. The device will produce sixteen 0.5 Amp beams of C+ at 2 MeV energy. The carbon arc source has been developed to the point where the emittance is within a factor of four of the design target. Modelling of the source behavior to find ways to reduce the emittance is discussed. Source lifetime and reliability is also of paramount importance to us and data regarding the lifetime and failure modes of different source configurations is discussed. One half of the accelerating column has been constructed and tested at high voltage. One beam experiments in this half column are underway. The second half of the column is being built and the transition 2 MV experiments should begin soon. In addition to beam and source performance we also discuss the controls for the injector and the electronics associated with the source and current injection. 3 refs., 2 figs

Electron beam synthesis of silica/nano silver composite and its application in controlling microorganisms in drinking water

International Nuclear Information System (INIS)

Ramnani, S.P.; Biswal, Jayashree; Sabharwal, S.; Rama Rao, K.C.; Sai Prasad, P.

2008-01-01

Silica/nano silver composites were prepared by electron beam (EB) irradiation technique. The solution containing silica nanoparticles and AgNO 3 in various proportion were subjected to EB irradiation. The EB dose delivered was such that all the Ag + is converted into metallic silver. The samples were characterized by XRD, SEM and TEM analysis. The composites were tested for their anti microbial activity in water samples. The results indicated that there is an optimum size of Ag nanoparticles that shows better antimicrobial activity. (author)

Transport and acceleration of the high-current ion beam in magneto-isolated gap

International Nuclear Information System (INIS)

Karas', V.I.; Kornilov, E.A.; Manuilenko, O.V.; Fedorovskaya, O.V.; Tarakanov, V.P.

2015-01-01

The possibility of transportation and acceleration of the high-current ion beam in the magneto-isolated gap has been demonstrated. Found the parameters of the system and beams (the magnetic field produced by the coils with opposing currents, the size of the system, and the parameters of the beams), under which the uniform acceleration of the high-current ion beam all along the gap length is realized. It is shown that the quality of the ion beam, during transport and acceleration, at the exit of the gap is acceptable for many technological applications.

Spin-resolved magnetic studies of focused ion beam etched nano-sized magnetic structures

International Nuclear Information System (INIS)

Li Jian; Rau, Carl

2005-01-01

Scanning ion microscopy with polarization analysis (SIMPA) is used to study the spin-resolved surface magnetic structure of nano-sized magnetic systems. SIMPA is utilized for in situ topographic and spin-resolved magnetic domain imaging as well as for focused ion beam (FIB) etching of desired structures in magnetic or non-magnetic systems. Ultra-thin Co films are deposited on surfaces of Si(1 0 0) substrates, and ultra-thin, tri-layered, bct Fe(1 0 0)/Mn/bct Fe(1 0 0) wedged magnetic structures are deposited on fcc Pd(1 0 0) substrates. SIMPA experiments clearly show that ion-induced electrons emitted from magnetic surfaces exhibit non-zero electron spin polarization (ESP), whereas electrons emitted from non-magnetic surfaces such as Si and Pd exhibit zero ESP, which can be used to calibrate sputtering rates in situ. We report on new, spin-resolved magnetic microstructures, such as magnetic 'C' states and magnetic vortices, found at surfaces of FIB patterned magnetic elements. It is found that FIB milling has a negligible effect on surface magnetic domain and domain wall structures. It is demonstrated that SIMPA can evolve into an important and efficient tool to study magnetic domain, domain wall and other structures as well as to perform magnetic depth profiling of magnetic nano-systems to be used in ultra-high density magnetic recording and in magnetic sensors

Wireless current sensing by near field induction from a spin transfer torque nano-oscillator

Energy Technology Data Exchange (ETDEWEB)

Ramaswamy, B. [Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742 (United States); Algarin, J. M.; Waks, E., E-mail: edowaks@umd.edu [Institute for Research in Electronics and Applied Physics (IREAP), University of Maryland, College Park, Maryland 20742 (United States); Weinberg, I. N. [Weinberg Medical Physics LLC, Bethesda, Maryland 20817 (United States); Chen, Y.-J.; Krivorotov, I. N. [Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States); Katine, J. A. [HGST Research Center, San Jose, California 95135 (United States); Shapiro, B. [Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742 (United States); Institute for Systems Research (ISR), University of Maryland, College Park, Maryland 20742 (United States)

2016-06-13

We demonstrate that spin transfer torque nano-oscillators (STNO) can act as wireless sensors for local current. The STNO acts as a transducer that converts weak direct currents into microwave field oscillations that we detect using an inductive coil. We detect direct currents in the range of 300–700 μA and report them wirelessly to a receiving induction coil at distances exceeding 6.5 mm. This current sensor could find application in chemical and biological sensing and industrial inspection.

Interaction of biodegradative threonine dehydratase (TD) of Escherichia coli with 8-azido-AMP, a photoaffinity analog of AMP

International Nuclear Information System (INIS)

Patil, R.V.; Datta, P.

1987-01-01

Stimulation of TD activity by AMP (Ka = 40 μM) is known to accompany the conversion of monomeric form of the enzyme to its tetramer and a decrease in the Km for threonine. In comparison, 8-azido-AMP (N 3 AMP) simulated TD activity only partially, lowered the Km for threonine and stabilized a dimeric form of the protein. Competition experiments revealed that N 3 AMP exerted an apparent dominant effect in counteracting the AMP-mediated enzyme activation, indicating complex mutual interactions between these ligands. UV irradiation of TD with increasing concentrations of 3 H-N 3 AMP (up to 150 μM) resulted in gradual loss of enzyme activity and concomitant incorporation of N 3 AMP into protein; upon complete inactivation, 0.75 mol of N 3 AMP was bound per mol tetramer. The presence of AMP during photolysis reduced the extent of enzyme inactivation as well as the incorporation of N 3 AMP into protein. Photolabeling of TD with 20 μM 3 H-N 3 AMP revealed one labeled tryptic peptide; at higher N 3 AMP concentrations (>300 μM), two labeled peptides were found, one of which was identical to that found with low N 3 AMP concentration. The cumulative results suggest that N 3 AMP can act as an allosteric modifier and that the peptide labeled at low N 3 AMP may represent the AMP binding site on the protein molecule

The study of photocatalysis under ultraviolet + visible two-beam light irradiation using undoped nano-titanium dioxide

International Nuclear Information System (INIS)

Liu Baoshun; Wen Liping; Zhao Xiujian

2008-01-01

The nano-TiO 2 powder was synthesized using wet chemical method and characterized by X-ray diffraction (XRD), Raman spectroscopy, Brunauer-Emmett-Teller (BET), and transmission electron microscope (TEM). The photodegradation of aqueous methyl orange and phenol under the irradiation of visible, ultraviolet (UV), and UV + visible lights was used to evaluate the photocatalytic activity of nano-TiO 2 powder prepared. It is found that the photocatalysis under UV and visible light irradiation simultaneously is much faster than the sum of that solely induced by UV light and visible light. UV-vis spectroscopy, photoluminescence (PL) spectroscopy, and X-ray photoelectron spectroscopy (XPS) were used to investigate the physical cause of the enhancement of photocatalytic activity induced by UV + visible two-beam light irradiation. A photocatalytic mechanism based on the d-d transition of photoinduced electrons on surface located at conduction band was suggested to explain the experimental result. It is considered that this is a novel method to utilize visible light in the photocatalysis by using undoped TiO 2 material

Nano structure Formations and Improvement in Corrosion Resistance of Steels by Means of Pulsed Electron Beam Surface Treatment

International Nuclear Information System (INIS)

Zhang, K.M.; Zou, J.X.; Zou, J.X.; Grosdidier, T.; Zou, J.X.; Grosdidier, T.; Grosdidier, T.

2013-01-01

The corrosion of steels has long been the topic for materials scientists. It is established that surface treatment is an efficient way to improve the corrosion resistance of steels without changing the bulk properties and with low costs. In the present paper, different kinds of surface treatment techniques for steels are briefly reviewed. In particular, the surface modification involving nano structure formations of steels by using a low energy high pulsed electron beam (LEHCPEB) treatment is lightened in the case of an AISI 316L stainless steel and D2 steel. The overall results demonstrate the high potential of the LEHCPEB technique for improving the corrosion performance of steels The corrosion of steels has long been the topic for materials scientists. It is established that surface treatment is an efficient way to improve the corrosion resistance of steels without changing the bulk properties and with low costs. In the present paper, different kinds of surface treatment techniques for steels are briefly reviewed. In particular, the surface modification involving nano structure formations of steels by using a low energy high pulsed electron beam (LEHCPEB) treatment is lightened in the case of an AISI 316L stainless steel and D2 steel. The overall results demonstrate the high potential of the LEHCPEB technique for improving the corrosion performance of steels

Reducing the beam current in Linac4 in pulse to pulse mode.

CERN Document Server

Lallement, JB; CERN. Geneva. BE Department

2009-01-01

In order to deliver different beam intensities to users, we studied the possibility of varying the Linac4 beam current at PS Booster injection in pulse to pulse mode. This report gives the possible configurations of Linac4 Low and Medium Energy Beam Transport lines (LEBT and MEBT) that lead to a consistent current reduction.

Vasotocin has the potential to inhibit basolateral Na(+)/K (+)-pump current across isolated skin of tree frog in vitro, via its V(2)-type receptor/cAMP pathway.

Science.gov (United States)

Takada, Makoto; Fujimaki, Kayo; Hokari, Shigeru

2008-11-01

Adult frog skin transports Na(+) from the apical to the basolateral side across the skin. Antidiuretic hormone (ADH) is involved in the regulation of Na(+) transport in both mammals and amphibians. We investigated the effect of arginine vasotocin (AVT), the ADH of amphibians, on the short-circuit current (SCC) across intact skin and on the basolateral Na(+)/K(+)-pump current across apically nystatin-permeabilized skin of the tree frog, Hyla japonica, in which the V(2)-type ADH receptor is expressed in vitro. In intact skin, 1 pM AVT had no effect on the SCC, but 10 nM AVT was sufficient to stimulate the SCC since 10 nM and 1 microM of AVT increased the SCC 3.2- and 3.4-fold, respectively (P > 0.9). However, in permeabilized skin, AVT (1 microM) decreased the Na(+)/K(+)-pump current to 0.79 times vehicle control. Similarly, 500 microM of 8Br-cAMP increased the SCC 3.2-fold, yet 1 mM of 8Br-cAMP decreased the Na(+)/K(+)-pump current to 0.76 times vehicle control. Arachidonic acid (10(-5) M) tended to decrease the Na(+)/K(+)-pump current. To judge from these in vitro experiments, AVT has the potential to inhibit the basolateral Na(+)/K(+)-pump current via the V(2)-type receptor/cAMP pathway in the skin of the tree frog.

Ion beam assisted synthesis of nano-crystals in glasses (silver and lead chalcogenides); Synthese assistee par faisceau d'ions d'agregats dans les verres (argent et chalcogenures de plomb)

Energy Technology Data Exchange (ETDEWEB)

Espiau de Lamaestre, R

2005-04-15

This work deals with the interest in ion beams for controlling nano-crystals synthesis in glasses. We show two different ways to reach this aim, insisting on importance of redox phenomena induced by the penetration and implantation of ions in glasses. We first show that we can use the great energy density deposited by the ions to tailor reducing conditions, favorable to metallic nano-crystal precipitation. In particular, we show that microscopic mechanism of radiation induced silver precipitation in glasses are analogous to the ones of classical photography. Ion beams can also be used to overcome supersaturation of elements in a given matrix. In this work, we synthesized lead chalcogenide nano-crystals (PbS, PbSe, PbTe) whose optical properties are interesting for telecommunication applications. We demonstrate the influence of complex chalcogenide chemistry in oxide glasses, and its relationship with the observed loss of growth control when nano-crystals are synthesized by sequential implantation of Pb and S in pure silica. As a consequence of this understanding, we demonstrate a novel and controlled synthesis of PbS nano-crystals, consisting in implanting sulfur into a Pb-containing glass, before annealing. Choice of glass composition provides a better control of precipitation physico-chemistry, whereas the use of implantation allows high nano-crystal volume fractions to be reached. Our study of IR emission properties of these nano-crystals shows a very high excitation cross section, and evidence for a 'dark exciton' emitting level. (author)

Application of radiofrequency superconductivity to accelerators for high-current ion beams

International Nuclear Information System (INIS)

Delayen, J.R.; Bohn, C.L.; Kennedy, W.L.; Roche, C.T.; Sagalovsky, L.

1992-01-01

A development program is underway to apply rf superconductivity to the design of continuous-wave (cw) linear accelerators for high-current, high-brightness ion beam. During the last few years, considerable progress has been made both experimentally and theoretically toward this application. Recent tests of niobium resonators for ion acceleration have yielded average accelerating gradients as high as 18 MV/m. In an experiment with a radio-frequency quadrupole geometry, niobium was found to sustain cw peak surface electric fields as high as 128 MV/m over large (10 cm) surface areas. Theoretical studies of beam halo, cumulative beam breakup and alternating-phase focusing have also yielded important results. This paper su-summarizes the recent progress and identifies current and future work in the areas of superconducting accelerator technology for high-current ion beams

Accurate electrostatic and van der Waals pull-in prediction for fully clamped nano/micro-beams using linear universal graphs of pull-in instability

Science.gov (United States)

Tahani, Masoud; Askari, Amir R.

2014-09-01

In spite of the fact that pull-in instability of electrically actuated nano/micro-beams has been investigated by many researchers to date, no explicit formula has been presented yet which can predict pull-in voltage based on a geometrically non-linear and distributed parameter model. The objective of present paper is to introduce a simple and accurate formula to predict this value for a fully clamped electrostatically actuated nano/micro-beam. To this end, a non-linear Euler-Bernoulli beam model is employed, which accounts for the axial residual stress, geometric non-linearity of mid-plane stretching, distributed electrostatic force and the van der Waals (vdW) attraction. The non-linear boundary value governing equation of equilibrium is non-dimensionalized and solved iteratively through single-term Galerkin based reduced order model (ROM). The solutions are validated thorough direct comparison with experimental and other existing results reported in previous studies. Pull-in instability under electrical and vdW loads are also investigated using universal graphs. Based on the results of these graphs, non-dimensional pull-in and vdW parameters, which are defined in the text, vary linearly versus the other dimensionless parameters of the problem. Using this fact, some linear equations are presented to predict pull-in voltage, the maximum allowable length, the so-called detachment length, and the minimum allowable gap for a nano/micro-system. These linear equations are also reduced to a couple of universal pull-in formulas for systems with small initial gap. The accuracy of the universal pull-in formulas are also validated by comparing its results with available experimental and some previous geometric linear and closed-form findings published in the literature.

Antimicrobial Peptides (AMPs

Directory of Open Access Journals (Sweden)

Mehrzad Sadredinamin

2016-04-01

Full Text Available Antimicrobial peptides (AMPs are extensive group of molecules that produced by variety tissues of invertebrate, plants, and animal species which play an important role in their immunity response. AMPs have different classifications such as; biosynthetic machines, biological sources, biological functions, molecular properties, covalent bonding patterns, three dimensional structures, and molecular targets.These molecules have multidimensional properties including antimicrobial activity, antiviral activity, antifungal activity, anti-parasite activity, biofilm control, antitumor activity, mitogens activity and linking innate to adaptive immunity that making them promising agents for therapeutic drugs. In spite of this advantage of AMPs, their clinical developments have some limitation for commercial development. But some of AMPs are under clinical trials for the therapeutic purpose such as diabetic foot ulcers, different bacterial infections and tissue damage. In this review, we emphasized on the source, structure, multidimensional properties, limitation and therapeutic applications of various antimicrobial peptides.

Beam profile monitor system for the bevalac transfer line

International Nuclear Information System (INIS)

Stover, G.

1985-01-01

Incorporated in the current Bevalac transfer line upgrade project is a proposal for a new electronic beam monitoring system. It will be designed to amplify, convert, and transmit the signals of twelve 16 by 16 multi-wire grids to a central computer located in the Bevatron control room. Each station will contain interface amplifiers and a local microprocessor to convert wire grid currents into digitized values which will then be transmitted via a serial data channel to the main computer. The system will have a large dynamic range (1 nano to 1 milli-ampere of beam current), be designed for distributed operation, and will be easily expandable. This paper describes the basic electronic hardware and software components of the proposed system

Nano- and micro-electromechanical systems fundamentals of nano- and microengineering

CERN Document Server

Lyshevski, Sergey Edward

2005-01-01

NANOTECHNOLOGY AND MICROTECHNOLOGY (NANO- AND MICRO- SCIENCE, ENGINEERING AND TECHNOLOGY), AND BEYOND Introduction and Overview: From Micro- to Nano- and Beyond to Stringo-Scale Introductory Definitions to the Subjects Current Developments and Needs for Coherent Revolutionary Developments Societal Challenges and Implications NANO- AND MICROSCALE SYSTEMS, DEVICES, AND STRUCTURES Sizing Features: From Micro- to Nano-, and from Nano- to Stringo-Scale MEMS and NEMS Definitions Introduction to Taxonomy of Nano- and Microsystem Synthesis and Design Introduction to Design and Optimization of Nano- and Microsystems in the Behavioral Domain NANO- AND MICROSYSTEMS: CLASSIFICATION AND CONSIDERATION Biomimetics, Biological Analogies,and Design of NEMS and MEMS Micro- and Nanoelectromechanical Systems: Scaling Laws and Mathematical Modeling MEMS Examples and MEMS Architectures Introduction to Microfabrication and Micromachining FUNDAMENTALS OF MICROFABRICATION AND MEMS FABRICATION TECHNOLOGIES Introducti...

Methods for calculating energy and current requirements for industrial electron beam processing

International Nuclear Information System (INIS)

Cleland, M.R.; Farrell, J.P.

1976-01-01

The practical problems of determining electron beam parameters for industrial irradiation processes are discussed. To assist the radiation engineer in this task, the physical aspects of electron beam absorption are briefly described. Formulas are derived for calculating the surface dose in the treated material using the electron energy, beam current and the area thruput rate of the conveyor. For thick absorbers electron transport results are used to obtain the depth-dose distributions. From these the average dose in the material, anti D, and the beam power utilization efficiency, F/sub p/, can be found by integration over the distributions. These concepts can be used to relate the electron beam power to the mass thruput rate. Qualitatively, the thickness of the material determines the beam energy, the area thruput rate and surface dose determine the beam current while the mass thruput rate and average depth-dose determine the beam power requirements. Graphs are presented showing these relationships as a function of electron energy from 0.2 to 4.0 MeV for polystyrene. With this information, the determination of electron energy and current requirements is a relatively simple procedure

Beam optics of the AmPS extraction line

International Nuclear Information System (INIS)

Hoekstra, R.

1991-01-01

The design of the Amsterdam Pulse Stretcher includes a feasibility study of part of the extraction trajectory. The latter includes some proposed curves projected through the hall of the beam switch yard. Since extraction is performed in the north line of the ring and the connection to the trajectory of the spectrometers is planned in a trajectory parallel to the east line of the ring the curves contain bending magnets for bending 90 degrees either by only two magnets or by making use of ring bending magnets in the same way as the ring curves are constructed. The bending through 90 degrees has optimal imaging properties of a unit cell much the same as the curves in the ring. This one-to-one (or one-to-minus-one) property is intended to shift the known required beam dimensions stream upwards from a defined point in the trajectory of the spectrometers to be able to create the dimensions at this shifted point by means of a so called beam transformer, placed in between the extraction point and this position. This report deals with the further developments with respect to the extraction trajectory. (author). 5 refs.; 9 figs.; 3 tabs

Nano-imaging of single cells using STIM

Energy Technology Data Exchange (ETDEWEB)

Ren Minqin [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Department of Biochemistry, National University of Singapore (Singapore); Kan, J.A. van [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Bettiol, A.A. [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Daina, Lim [Department of Anatomy, National University of Singapore (Singapore); Gek, Chan Yee [Department of Anatomy, National University of Singapore (Singapore); Huat, Bay Boon [Department of Anatomy, National University of Singapore (Singapore); Whitlow, H.J. [Department of Physics, University of Jyvaskyla, P.O. Box 35 (YFL), FIN-40014 (Finland); Osipowicz, T. [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Watt, F. [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542 (Singapore)]. E-mail: phywattf@nus.edu.sg

2007-07-15

Scanning transmission ion microscopy (STIM) is a technique which utilizes the energy loss of high energy (MeV) ions passing through a sample to provide structural images. In this paper, we have successfully demonstrated STIM imaging of single cells at the nano-level using the high resolution capability of the proton beam writing facility at the Centre for Ion Beam Applications, National University of Singapore. MCF-7 breast cancer cells (American Type Culture Collection [ATCC]) were seeded on to silicon nitride windows, backed by a Hamamatsu pin diode acting as a particle detector. A reasonable contrast was obtained using 1 MeV protons and excellent contrast obtained using 1 MeV alpha particles. In a further experiment, nano-STIM was also demonstrated using cells seeded on to the pin diode directly, and high quality nano-STIM images showing the nucleus and multiple nucleoli were extracted before the detector was significantly damaged.

Measurement of electron- and ion beam energies and currents in a plasma focus discharge

International Nuclear Information System (INIS)

Yamamoto, Toshikazu; Kondoh, Yoshiomi; Shimoda, Katsuji; Hirano, Katsumi

1982-01-01

Measurements of energetic particle beams in a plsma focus with a Mather type device are presented. Rogowski coils are used for time-resolved measurement, and solid-state nuclear track detectors for time-integrated measurement of the beams. In the upstream direction with respect to the discharge current, only the electron beam with the maximum current of several kA was detected, which was approximately one percent of the discharge current. The electron energies of the beam were spread from 0.1 to 1 MeV. In the downstream direction, two successive emissions of ions were observed. The first emission had an extremely high energy of the order of some MeV and a low beam current of less than 10 A. The second emission, the main part of the ion beam, with energies of 100 - 800 keV, followed the first one with a time lag of several tens of nanoseconds, and the beam current reached several tens of amperes. (author)

Improvement in current density of nano- and micro-structured Si solar cells by cost-effective elastomeric stamp process

Science.gov (United States)

Jeon, Kiseok; Jee, Hongsub; Lim, Sangwoo; Park, Min Joon; Jeong, Chaehwan

2018-03-01

Effective incident light should be controlled for improving the current density of solar cells by employing nano- and micro-structures on silicon surface. The elastomeric stamp process, which is more cost effective and simpler than conventional photolithography, was proposed for the fabrication of nano- and micro-structures. Polydimethylsiloxane (PDMS) was poured on a mother pattern with a diameter of 6 μm and a spacing of 2 μm; then, curing was performed to create a PDMS mold. The regular micropattern was stamped on a low-viscosity resin-coated silicon surface, followed by the simple reactive ion etching process. Nano-structures were formed using the Ag-based electroless etching process. As etching time was increased to 6 min, reflectance decreased to 4.53% and current density improved from 22.35 to 34.72 mA/cm2.

Resistive wall heating due to image current on the beam chamber for a superconducting undulator.

Energy Technology Data Exchange (ETDEWEB)

Kim, S. H. (Accelerator Systems Division (APS))

2012-03-27

The image-current heating on the resistive beam chamber of a superconducting undulator (SCU) was calculated based on the normal and anomalous skin effects. Using the bulk resistivity of copper for the beam chamber, the heat loads were calculated for the residual resistivity ratios (RRRs) of unity at room temperature to 100 K at a cryogenic temperature as the reference. Then, using the resistivity of the specific aluminum alloy 6053-T5, which will be used for the SCU beam chamber, the heat loads were calculated. An electron beam stored in a storage ring induces an image current on the inner conducting wall, mainly within a skin depth, of the beam chamber. The image current, with opposite charge to the electron beam, travels along the chamber wall in the same direction as the electron beam. The average current in the storage ring consists of a number of bunches. When the pattern of the bunched beam is repeated according to the rf frequency, the beam current may be expressed in terms of a Fourier series. The time structure of the image current is assumed to be the same as that of the beam current. For a given resistivity of the chamber inner wall, the application ofthe normal or anomalous skin effect will depend on the harmonic numbers of the Fourier series of the beam current and the temperature of the chamber. For a round beam chamber with a ratius r, much larger than the beam size, one can assume that the image current density as well as the density square, may be uniform around the perimeter 2{pi}r. For the SCU beam chamber, which has a relatively narrow vertical gap compared to the width, the effective perimeter was estimated since the heat load should be proportional to the inverse of the perimeter.

Design and finite element method analysis of laterally actuated multi-value nano electromechanical switches

KAUST Repository

Kloub, Hussam; Smith, Casey; Hussain, Muhammad Mustafa

2011-01-01

We report on the design and modeling of novel nano electromechanical switches suitable for implementing reset/set flip-flops, AND, NOR, and XNOR Boolean functions. Multiple logic operations can be implemented using only one switching action enabling parallel data processing; a feature that renders this design competitive with complementary metal oxide semiconductor and superior to conventional nano-electromechanical switches in terms of functionality per device footprint. The structural architecture of the newly designed switch consists of a pinned flexural beam structure which allows low strain lateral actuation for enhanced mechanical integrity. Reliable control of on-state electrical current density is achieved through the use of metal-metal contacts, true parallel beam deflection, and lithographically defined contact area to prevent possible device welding. Dynamic response as a function of device dimensions numerically investigated using ANSYS and MatLab Simulink. © 2011 The Japan Society of Applied Physics.

Design and finite element method analysis of laterally actuated multi-value nano electromechanical switches

KAUST Repository

Kloub, Hussam

2011-09-01

We report on the design and modeling of novel nano electromechanical switches suitable for implementing reset/set flip-flops, AND, NOR, and XNOR Boolean functions. Multiple logic operations can be implemented using only one switching action enabling parallel data processing; a feature that renders this design competitive with complementary metal oxide semiconductor and superior to conventional nano-electromechanical switches in terms of functionality per device footprint. The structural architecture of the newly designed switch consists of a pinned flexural beam structure which allows low strain lateral actuation for enhanced mechanical integrity. Reliable control of on-state electrical current density is achieved through the use of metal-metal contacts, true parallel beam deflection, and lithographically defined contact area to prevent possible device welding. Dynamic response as a function of device dimensions numerically investigated using ANSYS and MatLab Simulink. © 2011 The Japan Society of Applied Physics.

A low-cost non-intercepting beam current and phase monitor for heavy ions

International Nuclear Information System (INIS)

Bogaty, J.M.; Clifft, B.E.

1995-01-01

A low cost ion beam measurement system has been developed for use at ATLAS. The system provides nondestructive phase and intensity measurement of passing ion beam bunches by sensing their electric fields. Bunches traverse a short tubular electrode thereby inducing displacement currents. These currents are brought outside the vacuum jacket where a lumped inductance resonates electrode capacitance at one of the bunching harmonic frequencies. This configuration yields a basic sensitivity of a few hundred millivolts signal per microampere of beam current. Beam induced radiofrequency signals are summed against an offset frequency generated by the master oscillator. The resulting difference frequency conveys beam intensity and bunch phase information which is sent to separate processing channels. One channel utilizes a phase locked loop to stabilize phase readings during microsecond beam drop outs. The other channel uses a linear full-wave active rectifier circuit which converts sine wave signal amplitude to a DC voltage representing beam current. Plans are in progress to install this new diagnostic at several locations in ATLAS which should help shorten the tuning cycle of new ion species

A Novel Silicon-based Wideband RF Nano Switch Matrix Cell and the Fabrication of RF Nano Switch Structures

Directory of Open Access Journals (Sweden)

Yi Xiu YANG

2011-12-01

Full Text Available This paper presents the concept of RF nano switch matrix cell and the fabrication of RF nano switch. The nano switch matrix cell can be implemented into complex switch matrix for signal routing. RF nano switch is the decision unit for the matrix cell; in this research, it is fabricated on a tri-layer high-resistivity-silicon substrate using surface micromachining approach. Electron beam lithography is introduced to define the pattern and IC compatible deposition process is used to construct the metal layers. Silicon-based nano switch fabricated by IC compatible process can lead to a high potential of system integration to perform a cost effective system-on-a-chip solution. In this paper, simulation results of the designed matrix cell are presented; followed by the details of the nano structure fabrication and fabrication challenges optimizations; finally, measurements of the fabricated nano structure along with analytical discussions are also discussed.

Design and commissioning of the APS beam charge and current monitor

International Nuclear Information System (INIS)

Wang, X.; Lenkszus, F.; Rotela, E.

1994-01-01

The non-intercepting charge and current monitors suitable for a wide range of beam parameters have been developed and installed in the Advanced Photon Source (APS) low energy transport lines, positron accumulator ring (PAR), and injector synchrotron. The positron or electron beam pulse in the APS has charge ranging from 100pC to l0nC with pulse width varying from 30ps to 30ns. The beam charge and current are measured with a current transformer and subsequent current monitoring electronics based on an ultrafast, high precision gated integrator. The signal processing electronics, data acquisition, and communication with the control system are managed by a VME-based system. This paper summarizes the hardware and software features of the systems. The results of recent operations are presented

Design and commissioning of the APS beam charge and current monitors

International Nuclear Information System (INIS)

Wang, X.; Lenkszus, F.; Rotela, E.

1995-01-01

The non-intercepting charge and current monitors suitable for a wide range of beam parameters have been developed and installed in the Advanced Photon Source (APS) low energy transport lines, positron accumulator ring (PAR), and injector synchrotron. The positron or electron beam pulse in the APS has charge ranging from 100 pC to 10 nC with pulse width varying from 30 ps to 30 ns. The beam charge and current are measured with a current transformer and subsequent current monitoring electronics based on an ultrafast, high precision gated integrator. The signal processing electronics, data acquisition, and communication with the control system are managed by a VME-based system. This paper summarizes the hardware and software features of the systems. The results of recent operations are presented. copyright 1995 American Institute of Physics

X-ray lithography for micro- and nano-fabrication at ELETTRA for interdisciplinary applications

International Nuclear Information System (INIS)

Di Fabrizio, E; Fillipo, R; Cabrini, S

2004-01-01

ELETTRA (http://www.elettra.trieste.it/index.html) is a third generation synchrotron radiation source facility operating at Trieste, Italy, and hosts a wide range of research activities in advanced materials analysis and processing, biology and nano-science at several various beam lines. The energy spectrum of ELETTRA allows x-ray nano-lithography using soft (1.5 keV) and hard x-ray (10 keV) wavelengths. The Laboratory for Interdisciplinary Lithography (LIILIT) was established in 1998 as part of an Italian national initiative on micro- and nano-technology project of INFM and is funded and supported by the Italian National Research Council (CNR), INFM and ELETTRA. LILIT had developed two dedicated lithographic beam lines for soft (1.5 keV) and hard x-ray (10 keV) for micro- and nano-fabrication activities for their applications in engineering, science and bio-medical applications. In this paper, we present a summary of our research activities in micro- and nano-fabrication involving x-ray nanolithography at LILIT's soft and hard x-ray beam lines

2’,3’-cAMP, 3’-AMP, 2’-AMP and Adenosine Inhibit TNF-α and CXCL10 Production From Activated Primary Murine Microglia via A2A Receptors

Science.gov (United States)

Newell, Elizabeth A.; Exo, Jennifer L.; Verrier, Jonathan D.; Jackson, Travis C.; Gillespie, Delbert G.; Janesko-Feldman, Keri; Kochanek, Patrick M.

2014-01-01

Background Some cells, tissues and organs release 2’,3’-cAMP (a positional isomer of 3’,5’-cAMP) and convert extracellular 2’,3’-cAMP to 2’-AMP plus 3’-AMP and convert these AMPs to adenosine (called the extracellular 2’,3’-cAMP-adenosine pathway). Recent studies show that microglia have an extracellular 2’,3’-cAMP-adenosine pathway. The goal of the present study was to investigate whether the extracellular 2’,3’-cAMP-adenosine pathway could have functional consequences on the production of cytokines/chemokines by activated microglia. Methods Experiments were conducted in cultures of primary murine microglia. In the first experiment, the effect of 2’,3’-cAMP, 3’-AMP, 2’-AMP and adenosine on LPS-induced TNF-α and CXCL10 production was determined. In the next experiment, the first protocol was replicated but with the addition of 1,3-dipropyl-8-p-sulfophenylxanthine (DPSPX) (0.1 µM; antagonist of adenosine receptors). The last experiment compared the ability of 2-chloro-N6-cyclopentyladenosine (CCPA) (10 µM; selective A1 agonist), 5’-N-ethylcarboxamide adenosine (NECA) (10 µM; agonist for all adenosine receptor subtypes) and CGS21680 (10 µM; selective A2A agonist) to inhibit LPS-induced TNF-α and CXCL10 production. Results 1) 2’,3’-cAMP, 3’-AMP, 2’-AMP and adenosine similarly inhibited LPS-induced TNF-α and CXCL10 production; 2) DPSPX nearly eliminated the inhibitory effects of 2’,3’-cAMP, 3’-AMP, 2’-AMP and adenosine on LPS-induced TNF-α and CXCL10 production; 3) CCPA did not affect LPS-induced TNF-α and CXCL10; 4) NECA and CGS21680 similarly inhibited LPS-induced TNF-α and CXCL10 production. Conclusions 2’,3’-cAMP and its metabolites (3’-AMP, 2’-AMP and adenosine) inhibit LPS-induced TNF-α and CXCL10 production via A2A-receptor activation. Adenosine and its precursors, via A2A receptors, likely suppress TNF-α and CXCL10 production by activated microglia in brain diseases. PMID:25451117

Electron beam formation in high-current diode

International Nuclear Information System (INIS)

Korneev, S.A.

1981-01-01

The results of experimental investigation of the electron beam formation in diode with cathode on the base of incomplete discharge over the surface of dielectrics with dielectric penetration epsilon 2 . The measurement of current density distribution over transversal cross section reveals an efficient homogeneity [ru

Temperature calculations of heat loads in rotating target wheels exposed to high beam currents

International Nuclear Information System (INIS)

Greene, John P.; Gabor, Rachel; Neubauer, Janelle

2001-01-01

In heavy-ion physics, high beam currents can eventually melt or destroy the target. Tightly focused beams on stationary targets of modest melting point will exhibit short lifetimes. Defocused or 'wobbled' beams are employed to enhance target survival. Rotating targets using large diameter wheels can help overcome target melting and allow for higher beam currents to be used in experiments. The purpose of the calculations in this work is to try and predict the safe maximum beam currents which produce heat loads below the melting point of the target material

Temperature calculations of heat loads in rotating target wheels exposed to high beam currents

International Nuclear Information System (INIS)

Greene, J. P.; Gabor, R.; Neubauer, J.

2000-01-01

In heavy-ion physics, high beam currents can eventually melt or destroy the target. Tightly focused beams on stationary targets of modest melting point will exhibit short lifetimes. Defocused or wobbled beams are employed to enhance target survival. Rotating targets using large diameter wheels can help overcome target melting and allow for higher beam currents to be used in experiments. The purpose of the calculations in this work is to try and predict the safe maximum beam currents which produce heat loads below the melting point of the target material

Measurements of high-current electron beams from X pinches and wire array Z pinches

International Nuclear Information System (INIS)

Shelkovenko, T. A.; Pikuz, S. A.; Blesener, I. C.; McBride, R. D.; Bell, K. S.; Hammer, D. A.; Agafonov, A. V.; Romanova, V. M.; Mingaleev, A. R.

2008-01-01

Some issues concerning high-current electron beam transport from the X pinch cross point to the diagnostic system and measurements of the beam current by Faraday cups are discussed. Results of computer simulation of electron beam propagation from the pinch to the Faraday cup give limits for the measured current for beams having different energy spreads. The beam is partially neutralized as it propagates from the X pinch to a diagnostic system, but within a Faraday cup diagnostic, space charge effects can be very important. Experimental results show evidence of such effects.

Remote nano-optical beam focusing lens by illusion optics

Science.gov (United States)

Margousi, David; Shoorian, Hamed Reza

2014-08-01

In this paper, as a new application of illusion optics, a nano-optical plasmonic focusing lens structure is proposed to manipulate the light remotely by employing illusion optics theory. Plasmonic nano-optic lenses that enable super-focusing beyond the diffraction limit have been proposed as an alternative to the conventional dielectric-based refractive lenses. In the presence of an illusion device, the electromagnetic plane-waves can penetrate into a metal layer and a clear focus appears. When the illusion device is removed, waves are blocked to transmit through the metal wall. In comparison with conventional methods, our proposed method avoids any physical changes or damages in the original structure. The proposed structure can be realized by isotropic layered materials, using effective medium theory. The special feature of the proposed structure and the device concepts introduced in this work gives it an opportunity to be used as a flexible element in ultrahigh nano-scale integrated circuits for miniaturization and tuning purposes.

Cyclic AMP (cAMP)-mediated stimulation of adipocyte differentiation requires the synergistic action of Epac- and cAMP-dependent protein kinase-dependent processes

DEFF Research Database (Denmark)

Petersen, Rasmus Koefoed; Madsen, Lise; Pedersen, Lone Møller

2008-01-01

AMP-dependent stimulation of adipocyte differentiation. Epac, working via Rap, acted synergistically with cAMP-dependent protein kinase (protein kinase A [PKA]) to promote adipogenesis. The major role of PKA was to down-regulate Rho and Rho-kinase activity, rather than to enhance CREB phosphorylation. Suppression of Rho......-kinase impaired proadipogenic insulin/insulin-like growth factor 1 signaling, which was restored by activation of Epac. This interplay between PKA and Epac-mediated processes not only provides novel insight into the initiation and tuning of adipocyte differentiation, but also demonstrates a new mechanism of c......AMP signaling whereby cAMP uses both PKA and Epac to achieve an appropriate cellular response....

Pulsed high current ion beam processing equipment

International Nuclear Information System (INIS)

Korenev, S.A.; Perry, A.

1995-01-01

A pulsed high voltage ion source is considered for use in ion beam processing for the surface modification of materials, and deposition of conducting films on different substrates. The source consists of an Arkad'ev-Marx high voltage generator, a vacuum ion diode based on explosive ion emission, and a vacuum chamber as substrate holder. The ion diode allows conducting films to be deposited from metal or allow sources, with ion beam mixing, onto substrates held at a pre-selected temperature. The main variables can be set in the ranges: voltage 100-700 kV, pulse length 0.3 μs, beam current 1-200 A depending on the ion chosen. The applications of this technology are discussed in semiconductor, superconductor and metallizing applications as well as the direction of future development and cost of these devices for commercial application. 14 refs., 6 figs

MAST: a Mega Amp Spherical Tokamak

International Nuclear Information System (INIS)

Darke, A.C.; Harbar, J.R.; Hay, J.H.; Hicks, J.B.; Hill, J.W.; McKenzie, J.S.; Morris, A.W.; Nightingale, M.P.S.; Todd, T.N.; Voss, G.M.; Watkins, J.R.

1995-01-01

The highly successful tight aspect ratio tokamak research pioneered on the START machine at Culham, together with the attractive possibilities of the concept, suggest a larger device should be considered. The design of a Mega Amp Spherical Tokamak is described, operating at much higher currents and over longer pulses than START and compatible with strong additional heating. (orig.)

Finite element study of three dimensional radiative nano-plasma flow subject to Hall and ion slip currents

Directory of Open Access Journals (Sweden)

M. Nawaz

Full Text Available In this article, we developed a computer code of Galerikan Finite Element method (GFEM for three dimensional flow equations of nano-plasma fluid (blood in the presence of uniform applied magnetic field when Hall and ion slip current are significant. Lorentz force is calculated through generalized Ohm’s law with Maxwell equations. A series of numerical simulations are carried out to search ηmax and algebraic equations are solved by Gauss-Seidel method with simulation tolerance 10-8. Simulated results for special case have an excellent agreement with the already published results. Velocity components and temperature of the nano-plasma (blood are influenced significantly by the inclusion of nano-particles of Copper (Cu and Silver (Ag. Heat enhancement is observed when copper and silver nonmagnetic nanoparticles are used instead of simple base fluid (conventional fluid. Radiative nature of nano-plasma in the presence of magnetic field causes a decrease in the temperature due to the transfer of heat by the electromagnetic waves. In contrast to this, due to heat dissipated by Joule heating and viscous dissipation phenomena, temperature of nano-plasmaincreases as thermal radiation parameter is increased. Thermal boundary layer thickness can be controlled by using radiative fluid instead of non-radiative fluid. Momentum boundary layer thickness can be reduced by increasing the intensity of the applied magnetic field. Temperature of plasma in the presence magnetic field is higher than the plasma in the absence of magnetic field. Keywords: Nanofluid, Grid independent study, Convergence, Error analysis, Skin friction, Joule heating, Viscous dissipation, Hall and ion currents

Beam Current Increase and Cathode Lifetime Improvement of KOTRON-13 Ion Source

International Nuclear Information System (INIS)

Lee, W. K.; Chae, S. K.; Song, J. Y.; Im, G. S.; Cho, B. O.

2010-01-01

Technology of cyclotron has been actively developed to meet the increasing requirement output of medical radioactive isotopes for PET. KOTRON-13 is produced with low negative hydrogen ion beam current owing to the low efficiency of proton beam current compared with foreign cyclotron. In the defect there from, the lifetime of cathode is around 5,000min, which requires frequent maintenance period, and the target beam current is maximum 50uA at a poor efficiency compared with the inflow quantity of hydrogen gas and that of inflicting arc current. Considering above affairs, we have to improve the PIG ion source extraction efficiency of KOTRON-13 in order to lift beam current. Mostly the ion source of cyclotron less than 30Mev comes from the use of PIG ion source mainly with the method of cold cathode or hot cathode. However, the cyclotron of 30Mev grade of EBCO or IBA uses the external ion source and uses ion source with cusp type of good withdrawal efficiency. This type requires high voltage, and transports ion from ion source to cyclotron, which requires precise transportation equipment. And entering cyclotron requires a high quality of inflictor with a high defect rate, but high current cyclotron has no choice but to use ion source of such a method. But the cyclotron using PET with the beam current less than 100uA uses PIG ion source of KOTRON-13 with a reasonable maintenance cost

Beam physics design strategy for a high-current rf linac

Energy Technology Data Exchange (ETDEWEB)

Reiser, M. [Univ. of Maryland, College Park, MD (United States)

1995-10-01

The high average beam power of an rf linac system for transmutation of nuclear waste puts very stringent requirements on beam quality and beam control. Fractional beam losses along the accelerator must be kept at extremely low levels to assure {open_quotes}hands-on{close_quotes} maintenance. Hence, halo formation and large-amplitude tails in the particle distribution due to beam mismatch and equipartitioning effects must be avoided. This implies that the beam should ideally be in near-perfect thermal equilibrium from injection to full energy - in contrast to existing rf linacs in which the transverse temperature, T {sub {perpendicular}}, is higher than the longitudinal temperature, T{sub {parallel}}. The physics and parameter scaling for such a system will be reviewed using the results of recent work on high-intensity bunched beams. A design strategy for a high-current rf linac with equilibrated beam will be proposed.

Silicon radiation detector analysis using back electron beam induced current

International Nuclear Information System (INIS)

Guye, R.

1987-01-01

A new technique for the observation and analysis of defects in silicon radiation detectors is described. This method uses an electron beam from a scanning electron microscope (SEM) impinging on the rear side of the p + n junction of the silicon detector, which itself is active and detects the electron beam induced current (EBIC). It is shown that this current is a sensitive probe of localized trapping centers, either at the junction surface or somewhere in the volume of the silicon crystal. (orig.)

3' : 5'-Cyclic AMP-dependent 3'

NARCIS (Netherlands)

Mato, José M.; Krens, Frans A.; Haastert, Peter J.M. van; Konijn, Theo M.

1977-01-01

Suspensions of 3':5'-cyclic AMP (cAMP)-sensitive cells of Dictyostelium discoideum responded to a cAMP pulse with increased 3':5'-cyclic GMP (cGMP) levels. Under the assay conditions used (2 × 10^8 cells per ml in 10 mM phosphate buffer, pH 6.0) cAMP (5 × 10-8 M final concentration) increased cGMP

Fast-ion transport and neutral beam current drive in ASDEX upgrade

DEFF Research Database (Denmark)

Geiger, B.; Weiland, M.; Jacobsen, Asger Schou

2015-01-01

The neutral beam current drive efficiency has been investigated in the ASDEX Upgrade tokamak by replacing on-axis neutral beams with tangential off-axis beams. A clear modification of the radial fast-ion profiles is observed with a fast-ion D-alpha diagnostic that measures centrally peaked profiles...... during on-axis injection and outwards shifted profiles during off-axis injection. Due to this change of the fast-ion population, a clear modification of the plasma current profile is predicted but not observed by a motional Stark effect diagnostic. The fast-ion transport caused by MHD activity has been...

Zero-field precession and hysteretic threshold currents in a spin torque nano device with tilted polarizer

Energy Technology Data Exchange (ETDEWEB)

Zhou Yan; Bonetti, S; Zha, C L; Akerman, Johan [Department of Microelectronics and Applied Physics, Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden)], E-mail: zhouyan@kth.se

2009-10-15

Using nonlinear system theory and numerical simulations, we map out the static and dynamic phase diagrams in the zero applied field of a spin torque nano device with a tilted polarizer (TP). We find that for sufficiently large currents, even very small tilt angles ({beta}>1 deg.) will lead to steady free layer precession in zero field. Within a rather large range of tilt angles, 1 deg. <{beta}<19 deg., we find coexisting static states and hysteretic switching between these using only current. In a more narrow window (1 deg. <{beta}<5 deg.) one of the static states turns into a limit cycle (precession). The coexistence of current-driven static and dynamic states in the zero magnetic field is unique to the TP device and leads to large hysteresis in the upper and lower threshold currents for its operation. The nano device with TP can facilitate the generation of large amplitude mode of spin torque signals without the need for cumbersome magnetic field sources and thus should be very important for future telecommunication applications based on spin transfer torque effects.

Down-regulation of Cell Surface Cyclic AMP Receptors and Desensitization of Cyclic AMP-stimulated Adenylate Cyclase by Cyclic AMP in Dictyostelium discoideum. Kinetics and Concentration Dependence

NARCIS (Netherlands)

Haastert, Peter J.M. van

1987-01-01

cAMP binds to Dictyostelium discoideum surface receptors and induces a transient activation of adenylate cyclase, which is followed by desensitization. cAMP also induces a loss of detectable surface receptors (down-regulation). Cells were incubated with constant cAMP concentrations, washed free of

Generation of Low-Energy High-Current Electron Beams in Plasma-Anode Electron Guns

Science.gov (United States)

Ozur, G. E.; Proskurovsky, D. I.

2018-01-01

This paper is a review of studies on the generation of low-energy high-current electron beams in electron guns with a plasma anode and an explosive-emission cathode. The problems related to the initiation of explosive electron emission under plasma and the formation and transport of high-current electron beams in plasma-filled systems are discussed consecutively. Considerable attention is given to the nonstationary effects that occur in the space charge layers of plasma. Emphasis is also placed on the problem of providing a uniform energy density distribution over the beam cross section, which is of critical importance in using electron beams of this type for surface treatment of materials. Examples of facilities based on low-energy high-current electron beam sources are presented and their applications in materials science and practice are discussed.

Beam position dependence of a wall-current monitor

International Nuclear Information System (INIS)

Tamiya, K.; Asami, A.; Suwada, T.; Urano, T.; Kobayashi, H.

1995-01-01

It was pointed out recently that there exists an appreciable beam position dependence in the wall-current monitor widely used in electron accelerators. Detailed study of this dependence is performed on a test bench varying the pulse width and the frequency of the input signal simulating the beam. The results of experiments show that when the pulse width becomes shorter more appreciable becomes the dependence, and it approaches to that of calculated from the method of images. A unified analysis is under way. (author)

Fiscal 2000 survey report on technological trends. Survey on trend of high-density energy beam technology concerning conservation of energy; 2000 nendo gijutsu doko nado chosa hokokusho. Energy shiyo gorika ni kakawaru komitsudo energy beam technology no doko chosa

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

There is a possibility that machining technology using high-density energy beam will bring an epoch-making change to micro-nano area processing. In particular, a laser beam having high controllability is indispensable. This is a report of the fiscal 2000 survey. The survey was conducted on laser beam generation, control and nano-diagnostic techniques, micro-nano optics technologies and machining technologies, with the development problems and targets summarized. Laser beam generation/control technologies, which become the basic tools for micro-nano manufacturing, were investigated, as were inspection technologies for the purpose of checking the functions of nano structures created. Particularly, the investigation elucidated the significance of development of a femtosecond solid state laser based on a semiconductor laser and the control techniques of their phase. Further, necessity was emphasized in developing X-ray probing, infrared and terahertz spectroscopy which are essential for nano-diagnostic techniques. In optics technologies, the paper described the importance of photonic crystals which enable less-than-wavelength machining or electrical beam control using interference effect. The possibility of fabricating photocatalysts with nano-particles was also mentioned, as was the manufacturing of nano-functional structures. (NEDO)

Synthesis of nano-composite surfaces via the co-deposition of metallic salts and nano particles

Energy Technology Data Exchange (ETDEWEB)

MacFarlane, J.W.; Tesh, S.J.; Crane, R.A.; Hallam, K.R.; Scott, T.B.

2014-03-15

Highlights: • Nanofaceted surfaces are prepared by a low current density (<0.1 A cm{sup 2}) electrodeposition method. • Surfaces are formed of nanoparticles anchored to a conductive (carbon) substrate. • Formed surfaces show a high nano-reactivity and surface area. • Demonstration of INP/FeCl{sub 3} nanocomposite for water filtration effectively removing BTEX contamination. -- Abstract: A novel, low energy method for coating different nano-particles via electro-deposition to a recyclable carbon glass supporting structure is demonstrated. In the resulting composite, the nano-material is bound to the substrate surface, thereby removing the potential for causing harmful interactions with the environment. Nano-particles were suspended in a salt solution and deposited at low current densities (<0.1 A cm{sup −2}) producing thin (<100 nm), uniform nano-faceted surfaces. A co-deposition mechanism of nano-particles and cations from the salt solution is proposed and explored. This has been successfully demonstrated for iron, sliver, titanium in the current work. Furthermore, the removal of the surface coatings can be achieved via a reversed current applied over the system, allowing for the recovery of surface bound metal contaminants. The demonstrated applicability of this coating method to different nano-particle types, is useful in many areas within the catalysis and water treatment industries. One such example, is demonstrated, for the treatment of BTEX contamination and show a greatly improved efficiency to current leading remediation agents.

TeV/m nano-accelerator: Investigation on feasibility of CNT-channeling acceleration at Fermilab

Energy Technology Data Exchange (ETDEWEB)

Shin, Y. M. [Northern Illinois Univ., DeKalb, IL (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Lumpkin, A. H. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Thurman-Keup, R. M. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

2015-03-23

The development of high gradient acceleration and tight phase-space control of high power beams is a key element for future lepton and hadron colliders since the increasing demands for higher energy and luminosity significantly raise costs of modern HEP facilities. Atomic channels in crystals are known to consist of 10–100 V/Å potential barriers capable of guiding and collimating a high energy beam providing continuously focused acceleration with exceptionally high gradients (TeV/m). However, channels in natural crystals are only angstrom-size and physically vulnerable to high energy interactions, which has prevented crystals from being applied to high power accelerators. Carbon-based nano-crystals such as carbon-nanotubes (CNTs) and graphenes have a large degree of dimensional flexibility and thermo-mechanical strength, which could be suitable for channeling acceleration of MW beams. Nano-channels of the synthetic crystals can accept a few orders of magnitude larger phase-space volume of channeled particles with much higher thermal tolerance than natural crystals. This study presents the current status of CNT-channeling acceleration research at the Advanced Superconducting Test Accelerator (ASTA) in Fermilab.

Ion beams in materials processing and analysis

CERN Document Server

Schmidt, Bernd

2012-01-01

This book covers ion beam application in modern materials research, offering the basics of ion beam physics and technology and a detailed account of the physics of ion-solid interactions for ion implantation, ion beam synthesis, sputtering and nano-patterning.

The cyclic AMP cascade is altered in the fragile X nervous system.

Directory of Open Access Journals (Sweden)

Daniel J Kelley

2007-09-01

Full Text Available Fragile X syndrome (FX, the most common heritable cause of mental retardation and autism, is a developmental disorder characterized by physical, cognitive, and behavioral deficits. FX results from a trinucleotide expansion mutation in the fmr1 gene that reduces levels of fragile X mental retardation protein (FMRP. Although research efforts have focused on FMRP's impact on mGluR signaling, how the loss of FMRP leads to the individual symptoms of FX is not known. Previous studies on human FX blood cells revealed alterations in the cyclic adenosine 3', 5'-monophosphate (cAMP cascade. We tested the hypothesis that cAMP signaling is altered in the FX nervous system using three different model systems. Induced levels of cAMP in platelets and in brains of fmr1 knockout mice are substantially reduced. Cyclic AMP induction is also significantly reduced in human FX neural cells. Furthermore, cAMP production is decreased in the heads of FX Drosophila and this defect can be rescued by reintroduction of the dfmr gene. Our results indicate that a robust defect in cAMP production in FX is conserved across species and suggest that cAMP metabolism may serve as a useful biomarker in the human disease population. Reduced cAMP induction has implications for the underlying causes of FX and autism spectrum disorders. Pharmacological agents known to modulate the cAMP cascade may be therapeutic in FX patients and can be tested in these models, thus supplementing current efforts centered on mGluR signaling.

A stable partitioned FSI algorithm for incompressible flow and deforming beams

International Nuclear Information System (INIS)

Li, L.; Henshaw, W.D.; Banks, J.W.; Schwendeman, D.W.; Main, A.

2016-01-01

An added-mass partitioned (AMP) algorithm is described for solving fluid–structure interaction (FSI) problems coupling incompressible flows with thin elastic structures undergoing finite deformations. The new AMP scheme is fully second-order accurate and stable, without sub-time-step iterations, even for very light structures when added-mass effects are strong. The fluid, governed by the incompressible Navier–Stokes equations, is solved in velocity-pressure form using a fractional-step method; large deformations are treated with a mixed Eulerian-Lagrangian approach on deforming composite grids. The motion of the thin structure is governed by a generalized Euler–Bernoulli beam model, and these equations are solved in a Lagrangian frame using two approaches, one based on finite differences and the other on finite elements. The key AMP interface condition is a generalized Robin (mixed) condition on the fluid pressure. This condition, which is derived at a continuous level, has no adjustable parameters and is applied at the discrete level to couple the partitioned domain solvers. Special treatment of the AMP condition is required to couple the finite-element beam solver with the finite-difference-based fluid solver, and two coupling approaches are described. A normal-mode stability analysis is performed for a linearized model problem involving a beam separating two fluid domains, and it is shown that the AMP scheme is stable independent of the ratio of the mass of the fluid to that of the structure. A traditional partitioned (TP) scheme using a Dirichlet–Neumann coupling for the same model problem is shown to be unconditionally unstable if the added mass of the fluid is too large. A series of benchmark problems of increasing complexity are considered to illustrate the behavior of the AMP algorithm, and to compare the behavior with that of the TP scheme. The results of all these benchmark problems verify the stability and accuracy of the AMP scheme. Results for

A stable partitioned FSI algorithm for incompressible flow and deforming beams

Energy Technology Data Exchange (ETDEWEB)

Li, L., E-mail: lil19@rpi.edu [Department of Mathematical Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Henshaw, W.D., E-mail: henshw@rpi.edu [Department of Mathematical Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Banks, J.W., E-mail: banksj3@rpi.edu [Department of Mathematical Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Schwendeman, D.W., E-mail: schwed@rpi.edu [Department of Mathematical Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Main, A., E-mail: amain8511@gmail.com [Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708 (United States)

2016-05-01

An added-mass partitioned (AMP) algorithm is described for solving fluid–structure interaction (FSI) problems coupling incompressible flows with thin elastic structures undergoing finite deformations. The new AMP scheme is fully second-order accurate and stable, without sub-time-step iterations, even for very light structures when added-mass effects are strong. The fluid, governed by the incompressible Navier–Stokes equations, is solved in velocity-pressure form using a fractional-step method; large deformations are treated with a mixed Eulerian-Lagrangian approach on deforming composite grids. The motion of the thin structure is governed by a generalized Euler–Bernoulli beam model, and these equations are solved in a Lagrangian frame using two approaches, one based on finite differences and the other on finite elements. The key AMP interface condition is a generalized Robin (mixed) condition on the fluid pressure. This condition, which is derived at a continuous level, has no adjustable parameters and is applied at the discrete level to couple the partitioned domain solvers. Special treatment of the AMP condition is required to couple the finite-element beam solver with the finite-difference-based fluid solver, and two coupling approaches are described. A normal-mode stability analysis is performed for a linearized model problem involving a beam separating two fluid domains, and it is shown that the AMP scheme is stable independent of the ratio of the mass of the fluid to that of the structure. A traditional partitioned (TP) scheme using a Dirichlet–Neumann coupling for the same model problem is shown to be unconditionally unstable if the added mass of the fluid is too large. A series of benchmark problems of increasing complexity are considered to illustrate the behavior of the AMP algorithm, and to compare the behavior with that of the TP scheme. The results of all these benchmark problems verify the stability and accuracy of the AMP scheme. Results for

Two-section linear direct-current accelerator of 1.2 MeV electrons. Mean beam current of 50 mA

International Nuclear Information System (INIS)

Alimov, A.S.; Ermakov, D.I.; Ishkhanov, B.S.; Shvedunov, V.I.; Sakharov, V.P.; Trower, W.P.

2002-01-01

The theoretical and experimental results, obtained by simulation, creation and start-up of the two-section linear electron accelerator, are presented. The following beam parameters: beam current of 49 mA, mean energy of 1.2 MeV, of 59 kV, normalized emittance of 11 mm mrad are determined on the basis of the data on the beam dynamics simulation and the accelerating structure optimization. Special attention is paid to the choice of the version of the SHF-supply system of the two-section accelerator. The version of the SHF-supply system, based on the sections phasing, operating in the auto-oscillation model by means of the synchronizing signal from the feedback chain of the first section into the feedback chain of the second section, is considered. The electron beam parameters on the accelerator outlet (beam current - 44 mA, beam energy - 1.15 MeV, beam efficiency - 50.6 kW) proved to be close to the simulation results [ru

High Accuracy Beam Current Monitor System for CEBAF'S Experimental Hall A

International Nuclear Information System (INIS)

J. Denard; A. Saha; G. Lavessiere

2001-01-01

CEBAF accelerator delivers continuous wave (CW) electron beams to three experimental Halls. In Hall A, all experiments require continuous, non-invasive current measurements and a few experiments require an absolute accuracy of 0.2 % in the current range from 1 to 180 (micro)A. A Parametric Current Transformer (PCT), manufactured by Bergoz, has an accurate and stable sensitivity of 4 (micro)A/V but its offset drifts at the muA level over time preclude its direct use for continuous measurements. Two cavity monitors are calibrated against the PCT with at least 50 (micro)A of beam current. The calibration procedure suppresses the error due to PCT's offset drifts by turning the beam on and off, which is invasive to the experiment. One of the goals of the system is to minimize the calibration time without compromising the measurement's accuracy. The linearity of the cavity monitors is a critical parameter for transferring the accurate calibration done at high currents over the whole dynamic range. The method for measuring accurately the linearity is described

The detection of electron-beam-induced current in junctionless semiconductor

International Nuclear Information System (INIS)

Tan, Chee Chin; Ong, Vincent K. S.

2010-01-01

The scanning electron microscope is a versatile tool and its electron beam techniques have been widely used in semiconductor material and device characterizations. One of these electron beam techniques is the electron-beam-induced current (EBIC) technique. One of the limitations of the conventional EBIC technique is that it requires charge collecting junctions which may not be readily available in junctionless samples such as bare substrates unless some special sample preparation procedure such as the fabrication of a diffused junction is done on the junctionless sample. In this paper, the technique of detecting EBIC current in junctionless samples with the use of a two-point probe is presented. It is found that the EBIC current is independent from its physical parameter when the sample thickness is greater than 4L; the width to the right of probe 2 and the width to the left of probe 1 are greater than 2L and 8L, respectively. The parameters affecting this technique of detecting the EBIC current such as the depth of the generation volume, probe spacing, and the applied bias are also discussed in this paper. A commercially available two-dimensional device simulator was used to verify this technique.

Nano-structural characteristics and optical properties of silver chiral nano-flower sculptured thin films

International Nuclear Information System (INIS)

Savaloni, Hadi; Haydari-Nasab, Fatemh; Malmir, Mariam

2011-01-01

Silver chiral nano-flowers with 3-, 4- and 5-fold symmetry were produced using oblique angle deposition method in conjunction with the rotation of sample holder with different speeds at different sectors of each revolution corresponding to symmetry order of the acquired nano-flower. Atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM), were employed to obtain morphology and nano-structure of the films. Optical characteristics of silver chiral nano-flower thin films were obtained using single beam spectrophotometer with both s- and p-polarization incident light at 30 o and 70 o incidence angles and at different azimuthal angles (φ). Optical spectra showed both TM (TDM (transverse dipole mode) and TQM (transverse quadruple mode)) and LM (longitudinal mode) Plasmon resonance peaks. For 3- and 4-fold symmetry chiral nano-flowers the s-polarization extinction spectra obtained at different azimuthal angles did not show significant change in the Plasmon peak position while 5-fold symmetry chiral nano-flower showed a completely different behavior, which may be the result of increased surface anisotropy, so when the φ angle is changed the s-polarization response from the surface can change more significantly than that for lower symmetries. In general, for 3-, 4- and 5-fold symmetry chiral nano-flowers a sharp peak at lower wavelengths ( o incidence angle.

Cyclic AMP in rat pancreatic islets

International Nuclear Information System (INIS)

Grill, V.; Borglund, E.; Cerasi, E.; Uppsala Univ.

1977-01-01

The incorporation of [ 3 H]adenine into cyclic AMP was studied in rat pancreatic islets under varying conditions of labeling. Prolonging the exposure to [ 3 H]adenine progressively augmented the islet cyclic [ 3 H]AMP level. Islets labeled for different periods of time and subsequently incubated (without adenine) in the presence of D-glucose or cholera toxin showed stimulations of intra-islet cyclic [ 3 H]AMP that were proportionate to the levels of radioactive nucleotide present under non-stimulatory conditions. Labeling the islets in a high glucose concentration (27.7 mM) did not modify the nucleotide responses to glucose or cholera toxin. The specific activity of cyclic [ 3 H]AMP, determined by simultaneous assay of cyclic [ 3 H]AMP and total cyclic AMP, was not influenced by glucose or cholera toxin. Glucose had no effect on the specific activity of labeled ATP

PREFACE: 1st Nano-IBCT Conference 2011 - Radiation Damage of Biomolecular Systems: Nanoscale Insights into Ion Beam Cancer Therapy

Science.gov (United States)

Huber, Bernd A.; Malot, Christiane; Domaracka, Alicja; Solov'yov, Andrey V.

2012-07-01

The 1st Nano-IBCT Conference entitled 'Radiation Damage in Biomolecular Systems: Nanoscale Insights into Ion Beam Cancer Therapy' was held in Caen, France, in October 2011. The Meeting was organised in the framework of the COST Action MP1002 (Nano-IBCT) which was launched in December 2010 (http://fias.uni-frankfurt.de/nano-ibct). This action aims to promote the understanding of mechanisms and processes underlying the radiation damage of biomolecular systems at the molecular and nanoscopic level and to use the findings to improve the strategy of Ion Beam Cancer Therapy. In the hope of achieving this, participants from different disciplines were invited to represent the fields of physics, biology, medicine and chemistry, and also included those from industry and the operators of hadron therapy centres. Ion beam therapy offers the possibility of excellent dose localization for treatment of malignant tumours, minimizing radiation damage in normal healthy tissue, while maximizing cell killing within the tumour. Several ion beam cancer therapy clinical centres are now operating in Europe and elsewhere. However, the full potential of such therapy can only be exploited by better understanding the physical, chemical and biological mechanisms that lead to cell death under ion irradiation. Considering a range of spatio-temporal scales, the proposed action therefore aims to combine the unique experimental and theoretical expertise available within Europe to acquire greater insight at the nanoscopic and molecular level into radiation damage induced by ion impact. Success in this endeavour will be both an important scientific breakthrough and give great impetus to the practical improvement of this innovative therapeutic technique. Ion therapy potentially provides an important advance in cancer therapy and the COST action MP1002 will be very significant in ensuring Europe's leadership in this field, providing the scientific background, required data and mechanistic insight which

Beam-driven currents in the 1/ν regime in a helical system

International Nuclear Information System (INIS)

Nakajima, Noriyoshi; Okamoto, Masao.

1990-04-01

Beam currents driven by a neutral particle injection in a helical system (stellarator, heliotron/torsatron) are studied in the 1/ν collisionality regime. The general expression for the beam-driven current is obtained for arbitrary magnetic field configurations by solving the drift kinetic equation for electrons. It is found that F = J(net)/J(b) (J(net) is the net current and J(b) is the fast ion beam current) increases as f(t) and Zeff where f(t) is the fraction of trapped electrons and Zeff is the effective ionic charge number. Especially, for Zeff ≅ 1 the effect of trapped electrons is large and F is roughly proportional to f(t). On the other hand, if Zeff > or approx 3 the effect of trapped electrons becomes small. (author)

Microcontroller based four-channel current readout unit for beam slit monitor

International Nuclear Information System (INIS)

Holikatti, A.C.; Puntambekar, T.A.; Pithawa, C.K.

2009-01-01

This paper describes the design and development of a microcontroller based four-channel current readout unit for Beam Slit Monitor (BSM) installed in Transport Line-1 of Indus Accelerator Complex. BSM is a diagnostic device consisting of two horizontal and two vertical blades, which can be moved independently in to the beam pipe to cut the beam transversely. The readout unit employs switched integrators with reset, hold and select switches and timing and control unit. It integrates the current output of the four blades of BSM and produces an output corresponding to the beam charge intercepted by the blade. The integrator outputs are then multiplexed and digitized using 12-bit ADC. Acquired digital data from ADC is stored into on-chip RAM of the microcontroller. The readout sequence is synchronized with the Microtron beam-timing signal. The timing of integration, hold and reset cycles is controlled by the microcontroller. The unit is connected on a serial link to the host computer in main control room. This unit has been integrated with the BSM system and is being used to obtain the electron beam profile. (author)

S-AMP for non-linear observation models

DEFF Research Database (Denmark)

Cakmak, Burak; Winther, Ole; Fleury, Bernard H.

2015-01-01

Recently we presented the S-AMP approach, an extension of approximate message passing (AMP), to be able to handle general invariant matrix ensembles. In this contribution we extend S-AMP to non-linear observation models. We obtain generalized AMP (GAMP) as the special case when the measurement...

Development of an IH-type linac for the acceleration of high current heavy ion beams

Energy Technology Data Exchange (ETDEWEB)

Haehnel, Jan Hendrik

2017-07-20

The Facility for Antiproton and Ion Research (FAIR) at GSI Darmstadt will provide unprecedented intensities of protons and heavy ions up to uranium at energies of up to 29 GeV for protons and 2.7 GeV/u for U{sup 28+}. To achieve high intensities in the synchrotron accelerators, high beam currents have to be provided by the injector linear accelerators. High current heavy ion beams are provided by the Universal Linear Accelerator (UNILAC), which in its current state will not be able to provide the required FAIR beam currents. This thesis deals with the development of upgrades for the UNILAC to ensure its high current capability. The first improvement is a matching section (MEBT) for the interface between the RFQ and the IH-DTL of the existing high current injector HSI at the UNILAC. With this new MEBT section, particle losses are eliminated and the overall beam quality is improved. As a second improvement, a complete replacement of the existing Alvarez-DTL is presented. A combination of efficient IH-type cavities and KONUS beam dynamics results in a reduction of the linac length from about 60 m (Alvarez) to just 23 m (new IH-DTL) while providing the same energy and fulfilling FAIR requirements of a high beam current and beam quality. This thesis contains a detailed beam dynamics design of the new linac including some fundamental investigations of the KONUS beam dynamics concept. A cross-check of the beam dynamics design was performed with two independent multi-particle simulation codes. Detailed error studies were conducted to investigate the influence of manufacturing, alignment and operating errors on the beam dynamics performance. Additionally, all five linac cavities were designed, optimized, and their RF parameters including power requirements calculated to provide a comprehensive linac design.

Development of an IH-type linac for the acceleration of high current heavy ion beams

International Nuclear Information System (INIS)

Haehnel, Jan Hendrik

2017-01-01

The Facility for Antiproton and Ion Research (FAIR) at GSI Darmstadt will provide unprecedented intensities of protons and heavy ions up to uranium at energies of up to 29 GeV for protons and 2.7 GeV/u for U 28+ . To achieve high intensities in the synchrotron accelerators, high beam currents have to be provided by the injector linear accelerators. High current heavy ion beams are provided by the Universal Linear Accelerator (UNILAC), which in its current state will not be able to provide the required FAIR beam currents. This thesis deals with the development of upgrades for the UNILAC to ensure its high current capability. The first improvement is a matching section (MEBT) for the interface between the RFQ and the IH-DTL of the existing high current injector HSI at the UNILAC. With this new MEBT section, particle losses are eliminated and the overall beam quality is improved. As a second improvement, a complete replacement of the existing Alvarez-DTL is presented. A combination of efficient IH-type cavities and KONUS beam dynamics results in a reduction of the linac length from about 60 m (Alvarez) to just 23 m (new IH-DTL) while providing the same energy and fulfilling FAIR requirements of a high beam current and beam quality. This thesis contains a detailed beam dynamics design of the new linac including some fundamental investigations of the KONUS beam dynamics concept. A cross-check of the beam dynamics design was performed with two independent multi-particle simulation codes. Detailed error studies were conducted to investigate the influence of manufacturing, alignment and operating errors on the beam dynamics performance. Additionally, all five linac cavities were designed, optimized, and their RF parameters including power requirements calculated to provide a comprehensive linac design.

Electron gun design study for the IUCF beam cooling system

International Nuclear Information System (INIS)

Friesel, D.L.; Ellison, T.; Jones, W.P.

1985-01-01

The design of a low temperature electron beam cooling system for the Indiana University electron-cooled storage ring is in progress. The storage ring, which will accept the light ion beams from the existing k=200, multi-stage cyclotron facility, requires an electron beam variable in energy from about 7 to 275 keV. The electron beam system consists of a high perveance electron gun with Pierce geometry and a flat cathode. The gun and a 28 element accelerating column are immersed in a uniform longitudinal magnetic guide field. A computer modeling study of the system was conducted to determine electron beam density and transverse temperature variations as a function of anode region and accelerator column design parameters. Transverse electron beam temperatures (E /SUB t/ = mc 2 β 2 γ(/theta/ /SUB H/ +/theta/ /SUB v/ )) of less than a few tenths of an electron volt at a maximum current density of 0.4 A/cm 2 are desired over the full energy range. This was achieved in the calculations without the use of resonant focusing for a 2 Amp, 275 keV electron beam. Some systematics of the electron beam temperature variations with system design parameters are presented. A short discussion of the mechanical design of the proposed electron beam system is also given

Complete mechanical behavior analysis of FG Nano Beam under non-uniform loading using non-local theory

Science.gov (United States)

Ghaffari, I.; Parhizkar Yaghoobi, M.; Ghannad, M.

2018-01-01

The purpose of this study is to offer a complete solution to analyze the mechanical behavior (bending, buckling and vibration) of Nano-beam under non-uniform loading. Furthermore, the effects of size (nonlocal parameters), non-homogeneity constants, and different boundary conditions are investigated by using this method. The exact solution presented here reduces costs incurred by experiments. In this research, the displacement field obeys the kinematics of the Euler-Bernoulli beam theory and non-local elasticity theory has been used. The governing equations and general boundary conditions are derived for a beam by using energy method. The presented solution enables us to analyze any kind of loading profile and boundary conditions with no limitations. Furthermore, this solution, unlike previous studies, is not a series-solution; hence, there is no limitation prior to existing with the series-solution, nor does it need to check convergence. Based on the developed analytical solution, the influence of size, non-homogeneity and non-uniform loads on bending, buckling and vibration behaviors is discussed. Also, the obtained result is highly accurate and in good agreement with previous research. In theoretical method, the allowable range for non-local parameters can be determined so as to make a major contribution to the reduction of the cost of experiments determining the value of non-local parameters.

Design of inductively detuned RF extraction cavities for the Relativistic Klystron Two Beam Accelerator

International Nuclear Information System (INIS)

Henestroza, E.; Yu, S.S.; Li, H.

1995-04-01

An inductively detuned traveling wave cavity for the Relativistic Klystron Two Beam Accelerator expected to extract high RF power at 11. 424 GHz for the 1 TeV Center of Mass Next Linear Collider has been designed. Longitudinal beam dynamics studies led to the following requirements on cavity design: (a) Extraction of 360 MW of RF power with RF component of the current being 1.15 kAmps at 11.424 GHz, (b) Inductively detuned traveling wave cavity with wave phase velocity equal to 4/3 the speed of light, (c) Output cavity with appropriate Q ext and eigenfrequency for proper matching. Furthermore, transverse beam dynamics require low shunt impedances to avoid the beam break-up instability. We describe the design effort to meet these criteria based on frequency-domain and time-domain computations using 2D- and 3D- electromagnetic codes

Wideband Precision Current Transformer for the Magnet Current of the Beam Extraction Kicker Magnet of the Large Hadron Collider

CERN Document Server

Gräwer, G

2004-01-01

The LHC beam extraction system is composed of 15 fast kicker magnets per beam to extract the particles in one turn of the collider and to safely dispose them on external absorbers. Each magnet is powered by a separate pulse generator. The generator produces a magnet current pulse with 3 us rise time, 20 kA amplitude and 1.8 ms fall time, of which 90 us are needed to dump the beam. The beam extraction system requires a high level of reliability. To detect any change in the magnet current characteristics, which might indicate a slow degradation of the pulse generator, a high precision wideband current transformer will be installed. For redundancy reasons, the results obtained with this device will be cross-checked with a Rogowski coil, installed adjacent to the transformer. A prototype transformer has been successfully tested at nominal current levels and showed satisfactory results compared with the output of a high frequency resistive coaxial shunt. The annular core of the ring type transformer is composed of...

42 CFR 447.504 - Determination of AMP.

Science.gov (United States)

2010-10-01

... 42 Public Health 4 2010-10-01 2010-10-01 false Determination of AMP. 447.504 Section 447.504... AMP. (a) AMP means, with respect to a covered outpatient drug of a manufacturer (including those sold... wholesalers for drugs distributed to the retail pharmacy class of trade. AMP shall be determined without...

Development of a radio-frequency quadrupole cooler for high beam currents

Science.gov (United States)

Boussaid, Ramzi; Ban, G.; Quéméner, G.; Merrer, Y.; Lorry, J.

2017-12-01

The SHIRaC prototype is a recently developed radio-frequency quadrupole (RFQ) beam cooler with an improved optics design to deliver the required beam quality to a high resolution separator (HRS). For an isobaric separation of isotopes, the HRS demands beams with emittance not exceeding 3 π mm mrad and longitudinal energy spread ˜1 eV . Simulation studies showed a significant contribution of the buffer gas diffusion, space charge effect and mainly the rf fringe field to degrade the achieved beam quality at the RFQ exit. A miniature rf quadrupole (μ RFQ ) has been implemented at that exit to remove the degrading effects and provide beams with 1 eV of energy spread and around 1.75 π mm mrad of emittance for 4 Pa gas pressure. This solution enables also to transmit more than 60% of the incoming ions for currents up to 1 μ A . Detailed studies of this development are presented and discussed in this paper. Transport of beams from SHIRaC towards the HRS has been done with an electrostatic quadrupole triplet. Simulations and first experimental tests showed that more than 95% of ions can reach the HRS. Because SPIRAL-2 beams are of high current and very radioactive, the buffer gas will be highly contaminated. Safe maintenance of the SHIRaC beam line needs exceptional treatment of radioactive contaminants. For that, special vinyl sleep should be mounted on elements to be maintained. A detailed maintenance process will be presented.

Comparison between nano-diamond and carbon nanotube doping effects on critical current density and flux pinning in MgB2

International Nuclear Information System (INIS)

Cheng, C H; Yang, Y; Munroe, P; Zhao, Y

2007-01-01

Doping effects of nano-diamond and carbon nanotubes (CNTs) on critical current density of bulk MgB 2 have been studied. CNTs are found prone to be doped into the MgB 2 lattice whereas nano-diamond tends to form second-phase inclusions in the MgB 2 matrix, leading to a more significant improvement of J c (H) by doping by nano-diamond than by CNTs in MgB 2 . TEM reveals tightly packed MgB 2 nanograins (50-100 nm) with a dense distribution of diamond nanoparticles (10-20 nm) inside MgB 2 grains in nano-diamond-doped samples. Such a unique microstructure leads to a flux pinning behaviour different from that in CNTs-doped MgB 2

Focused ion beam milling of carbon fibres

International Nuclear Information System (INIS)

Huson, Mickey G.; Church, Jeffrey S.; Hillbrick, Linda K.; Woodhead, Andrea L.; Sridhar, Manoj; Van De Meene, Allison M.L.

2015-01-01

A focused ion beam has been used to mill both individual carbon fibres as well as fibres in an epoxy composite, with a view to preparing flat surfaces for nano-indentation. The milled surfaces have been assessed for damage using scanning probe microscopy nano-indentation and Raman micro-probe analysis, revealing that FIB milling damages the carbon fibre surface and covers surrounding areas with debris of disordered carbon. The debris is detected as far as 100 μm from the milling site. The energy of milling as well as the orientation of the beam was varied and shown to have an effect when assessed by Raman spectroscopy. - Highlights: • Focused ion beam (FIB) milling was used to mill flat surfaces on carbon fibres. • Raman spectroscopy showed amorphous carbon was generated during FIB milling. • The amorphous debris is detected as far as 100 μm from the milling site. • This surface degradation was confirmed by nano-indentation experiments.

Measurements of current density distribution in shaped e-beam writers

Czech Academy of Sciences Publication Activity Database

Bok, Jan; Horáček, Miroslav; Kolařík, Vladimír; Urbánek, Michal; Matějka, Milan; Krzyžánek, Vladislav

2016-01-01

Roč. 149, JAN 5 (2016), s. 117-124 ISSN 0167-9317 R&D Projects: GA ČR(CZ) GA14-20012S; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : shaped e-beam writer * electron beam * current density Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 1.806, year: 2016

Nonlinear Charge and Current Neutralization of an Ion Beam Pulse in a Pre-formed Plasma

International Nuclear Information System (INIS)

Kaganovich, Igor D.; Shvets, Gennady; Startsev, Edward; Davidson, Ronald C.

2001-01-01

The propagation of a high-current finite-length ion beam in a cold pre-formed plasma is investigated. The outcome of the calculation is the quantitative prediction of the degree of charge and current neutralization of the ion beam pulse by the background plasma. The electric magnetic fields generated by the ion beam are studied analytically for the nonlinear case where the plasma density is comparable in size with the beam density. Particle-in-cell simulations and fluid calculations of current and charge neutralization have been performed for parameters relevant to heavy ion fusion assuming long, dense beams with el >> V(subscript b)/omega(subscript b), where V(subscript b) is the beam velocity and omega subscript b is the electron plasma frequency evaluated with the ion beam density. An important conclusion is that for long, nonrelativistic ion beams, charge neutralization is, for all practical purposes, complete even for very tenuous background plasmas. As a result, the self-magnetic force dominates the electric force and the beam ions are always pinched during beam propagation in a background plasma

Nonlinear Charge and Current Neutralization of an Ion Beam Pulse in a Pre-formed Plasma

Energy Technology Data Exchange (ETDEWEB)

Igor D. Kaganovich; Gennady Shvets; Edward Startsev; Ronald C. Davidson

2001-01-30

The propagation of a high-current finite-length ion beam in a cold pre-formed plasma is investigated. The outcome of the calculation is the quantitative prediction of the degree of charge and current neutralization of the ion beam pulse by the background plasma. The electric magnetic fields generated by the ion beam are studied analytically for the nonlinear case where the plasma density is comparable in size with the beam density. Particle-in-cell simulations and fluid calculations of current and charge neutralization have been performed for parameters relevant to heavy ion fusion assuming long, dense beams with el >> V(subscript b)/omega(subscript b), where V(subscript b) is the beam velocity and omega subscript b is the electron plasma frequency evaluated with the ion beam density. An important conclusion is that for long, nonrelativistic ion beams, charge neutralization is, for all practical purposes, complete even for very tenuous background plasmas. As a result, the self-magnetic force dominates the electric force and the beam ions are always pinched during beam propagation in a background plasma.

CZT nanoRAIDER_VFG Factsheet

Energy Technology Data Exchange (ETDEWEB)

James, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Bolotnikov, A. E. [Brookhaven National Lab. (BNL), Upton, NY (United States); Cui, Yonggang [Brookhaven National Lab. (BNL), Upton, NY (United States)

2016-01-15

Brookhaven National Laboratory (BNL) is working with FLIR System Inc., the manufacturer of the nanoRAIDER, to design a handheld device based on a position-sensitive virtual Frisch-grid (VFG) Cadmium-Zinc-Telluride (CdZnTe or CZT) detector array (with 1% or better energy resolution). The new device called nanoRAIDER VFG will be an improvement to the current nanoRAIDER, which is a compact gamma-ray detection instrument manufactured by FLIR Systems Inc. that employs relatively lower-performing CZT hemispheric detectors (i.e., 3%-FWHM CZT detectors). The nanoRAIDER will significantly improve the accuracy while maintaining similar efficiency, as compared to the nanoRAIDER, for in-field analysis of nuclear materials and detection of undeclared activities during inspections conducted by the International Atomic Energy Agency (IAEA). Since the nanoRAIDER is currently used by the IAEA as part of its Complementary Access toolkit, a relatively quick acceptance of the nanoRAIDER VFG for safeguards is anticipated. The nanoRAIDER VFG will help address several items listed in the IAEA’s Long-Term R&D Plan that could enhance the abilities to detect undeclared nuclear material and activities.

A Fast Non Intercepting Linac Electron Beam Position and Current Monitor

DEFF Research Database (Denmark)

Hansen, Jørgen-Walther; Wille, Mads

1982-01-01

A non-intercepting beam monitor consisting of four detecting loops is used to determine the spatial postion and current of a pulsed beam from an electron linear accelerator. The monitor detects the magnetic field radiated by the substructure of the electron bunches created by the accelerating...

Combined addition of nano diamond and nano SiO2, an effective method to improve the in-field critical current density of MgB2 superconductor

International Nuclear Information System (INIS)

Rahul, S.; Varghese, Neson; Vinod, K.; Devadas, K.M.; Thomas, Syju; Anees, P.; Chattopadhyay, M.K.; Roy, S.B.; Syamaprasad, U.

2011-01-01

Highlights: → Both nano diamond and nano SiO 2 caused significant modifications in the structural properties of pure MgB 2 sample. → Reduction in T C for the best codoped sample was approximately 2 K. → The best codoped sample yielded a J C , an order of magnitude more than the undoped one at 5 K and 8 T. → The enhanced flux pinning capability provided by the additives is responsible for the improved in-field J C . -- Abstract: MgB 2 bulk samples added with nano SiO 2 and/or nano diamond were prepared by powder-in-sealed-tube (PIST) method and the effects of addition on structural and superconducting properties were studied. X-ray diffraction (XRD) analysis revealed that the addition caused systematic reduction in 'a' lattice parameter due to the substitution of C atoms at B sites and the strain caused by reacted intragrain nano particles of Mg 2 Si as evinced by transmission electron microscope image. Scanning electron microscopy images showed distinct microstructural variations with SiO 2 /diamond addition. It was evident from DC magnetization measurements that the in-field critical current density [J C (H)] of doped samples did not fall drastically like the undoped sample. Among the doped samples the J C (H) of co-doped samples were significantly higher and the best co-doped sample yielded a J C , an order of magnitude more than the undoped one at 5 K and 8 T.

Guiding effect of bent macroscopic quartz tube for high current electron beam

International Nuclear Information System (INIS)

Zhang Mingwu; Chen Jing; Wu Yehong; Yang Bian; Wang Wei; Xue Yingli; Yu Deyang; Cai Xiaohong

2012-01-01

By using an incident electron beam with the high current and high energy, the guiding effect of the bent macroscopic quartz tube for the electron beam has been investigated. The angular distributions of outgoing electrons depending on the current and energy of incident electrons were measured. The dependences of electron transmitted fraction on energy and current of incident electrons are also shown. As the incident electron energy increasing, the electron transmitted fraction increases, but it decreases while the incident electron current increasing. The results have been compared with the present data. This work presents, the process of guiding electrons is essentially different from that of guiding highly charged ions, the guiding electron beam was caused by both elastic and inelastic collisions between electrons and inner walls of quartz tube, rather than self-organized charging effect on the surface of inner wall of quartz tube. (authors)

Ampère–Maxwell law for a conducting wire: a topological perspective

International Nuclear Information System (INIS)

Ferreira, J M; Anacleto, Joaquim

2013-01-01

The integral form of Ampère–Maxwell's law for an arbitrarily-shaped wire is recast from a topological perspective, eliminating the need to use conduction current and displacement current terms to determine the magnetic field circulation around an arbitrarily-shaped loop. A generalized flux of the electric field is defined, enabling Ampère–Maxwell's law for magnetic field circulation to be written in a form which parallels that in the absence of conduction current. It is hoped that this work has educational interest since it provides an example of how topology can simplify the formulation of physical laws. The ideas presented herein are primarily intended for undergraduate students of electromagnetism, but may also be of interest to graduate students and teachers. (paper)

Development of a high current 60 keV neutral lithium beam injector for beam emission spectroscopy measurements on fusion experiments

Science.gov (United States)

Anda, G.; Dunai, D.; Lampert, M.; Krizsanóczi, T.; Németh, J.; Bató, S.; Nam, Y. U.; Hu, G. H.; Zoletnik, S.

2018-01-01

A 60 keV neutral lithium beam system was designed and built up for beam emission spectroscopy measurement of edge plasma on the KSTAR and EAST tokamaks. The electron density profile and its fluctuation can be measured using the accelerated lithium beam-based emission spectroscopy system. A thermionic ion source was developed with a SiC heater to emit around 4-5 mA ion current from a 14 mm diameter surface. The ion optic is following the 2 step design used on other devices with small modifications to reach about 2-3 cm beam diameter in the plasma at about 4 m from the ion source. A newly developed recirculating sodium vapour neutralizer neutralizes the accelerated ion beam at around 260-280 °C even during long (manipulation techniques are applied to allow optimization, aiming, cleaning, and beam modulation. The maximum 60 keV beam energy with 4 mA ion current was successfully reached at KSTAR and at EAST. Combined with an efficient observation system, the Li-beam diagnostic enables the measurement of the density profile and fluctuations on the plasma turbulence time scale.

Track-etch membranes enabled nano-/microtechnology: A review

International Nuclear Information System (INIS)

Chakarvarti, S.K.

2009-01-01

The art and science of fabricating structures with nano-/micrometric dimensions as well as precision is of the immense concern to any one investigating into nano-/microtechnology. The synergetic support of radiation and its potential in combining radiation effects with nano-/micromaterials has been recognized from the very early stages of nano-science research. In the myriad of applications and uses of nano-/microstructures, and nano particles in particular, from filtration, fabrication of biosensors, a chemical catalysis, magnetic structures, nano-electronics, MEMS, mechano-chemical conversion, quantum computing etc to name a few, radiation can play a significant role. One such potential application is track-etch membranes- a spin-off from the matter-radiation interaction. In the recent years, there has been a tremendous leap in the potential applications of metallic as well as non-metallic nano-/microstructures and materials. Nanotechnology has initiated a big hop and appears to be all set for bringing in revolution in the development and advancement of techniques involved in the synthesis and fabrication of sensors and devices. The conventional techniques for fabrication of very low dimensional wires - say quantum wires, include wet chemistry, electron beam lithography, focused ion beam techniques and atomic-beam lithography but for certain drawbacks and problems mentioned further. That has shown the ways for adopting newer alternative approaches which are relatively inexpensive, easier to handle and synergistically adorned with high efficacy. It is now well known that size of the devices and components dictate many unusual traits where quantum effects become more predominant. Quasi-one-dimensional nanostructures and materials like nanowires, fibres, tubules etc, having high aspect ratio would provide unusual and uncommon properties. Some properties like strength and hardness enhancement, dramatic changes in electrical conduction, field-ion-emission through

Track-etch membranes enabled nano-/microtechnology: A review

Energy Technology Data Exchange (ETDEWEB)

Chakarvarti, S.K., E-mail: skchakarvarti@gmail.co [Department of Physics, National Institute of Technology, Institution of National Importance, Kurukshetra 136 119 (India)

2009-10-15

The art and science of fabricating structures with nano-/micrometric dimensions as well as precision is of the immense concern to any one investigating into nano-/microtechnology. The synergetic support of radiation and its potential in combining radiation effects with nano-/micromaterials has been recognized from the very early stages of nano-science research. In the myriad of applications and uses of nano-/microstructures, and nano particles in particular, from filtration, fabrication of biosensors, a chemical catalysis, magnetic structures, nano-electronics, MEMS, mechano-chemical conversion, quantum computing etc to name a few, radiation can play a significant role. One such potential application is track-etch membranes- a spin-off from the matter-radiation interaction. In the recent years, there has been a tremendous leap in the potential applications of metallic as well as non-metallic nano-/microstructures and materials. Nanotechnology has initiated a big hop and appears to be all set for bringing in revolution in the development and advancement of techniques involved in the synthesis and fabrication of sensors and devices. The conventional techniques for fabrication of very low dimensional wires - say quantum wires, include wet chemistry, electron beam lithography, focused ion beam techniques and atomic-beam lithography but for certain drawbacks and problems mentioned further. That has shown the ways for adopting newer alternative approaches which are relatively inexpensive, easier to handle and synergistically adorned with high efficacy. It is now well known that size of the devices and components dictate many unusual traits where quantum effects become more predominant. Quasi-one-dimensional nanostructures and materials like nanowires, fibres, tubules etc, having high aspect ratio would provide unusual and uncommon properties. Some properties like strength and hardness enhancement, dramatic changes in electrical conduction, field-ion-emission through

Soft X-ray beam induced current technique

Energy Technology Data Exchange (ETDEWEB)

Watts, B; Ade, H [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States); Queen, D; Hellman, F [Department of Physics, University of California, Berkeley, CA 94720 (United States); Kilcoyne, A L D; Tyliszczak, T, E-mail: benjamin.watts@gmail.co [Advanced Light Source, Lawrence Berkeley Nat. Lab., Berkeley, CA 94720 (United States)

2009-09-01

Direct mapping of the charge transport efficiency of polymer solar cell devices using a soft X-ray beam induced current (SoXBIC) method is described. By fabricating a polymer solar cell on an x-ray transparent substrate, we demonstrate the ability to map polymer composition and nanoscale structure within an operating solar cell device and to simultaneously measure the local charge transport efficiency via the short-circuit current. A simple model is calculated and compared to experimental SoXBIC data of a PFB:F8BT bulk-heterojunction device in order to gain greater insight into the device operation and physics.

A review of high beam current RFQ accelerators and funnels

International Nuclear Information System (INIS)

Schneider, J.D.

1998-01-01

The authors review the design features of several high-current (> 20-mA) and high-power (> 1-mA average) proton or H - injectors, RFQs, and funnels. They include a summary of observed performance and will mention a sampling of new designs, including the proposed incorporation of beam choppers. Different programs and organizations have chosen to build the RFQ in diverse configurations. Although the majority of RFQs are either low-current or very low duty-factor, several versions have included high-current and/or high-power designs for either protons or H - ions. The challenges of cooling, handling high space-charge forces, and coupling with injectors and subsequent accelerators are significant. In all instances, beam tests were a valuable learning experience, because not always did these as-built structures perform exactly as predicted by the earlier design codes. They summarize the key operational parameters, indicate what was achieved, and highlight what was learned in these tests. Based on this generally good performance and high promise, even more challenging designs are being considered for new applications that include even higher powers, beam funnels and choppers

Label-free detection of DNA hybridization and single point mutations in a nano-gap biosensor

International Nuclear Information System (INIS)

Zaffino, R L; Mir, M; Samitier, J

2014-01-01

We describe a conductance-based biosensor that exploits DNA-mediated long-range electron transport for the label-free and direct electrical detection of DNA hybridization. This biosensor platform comprises an array of vertical nano-gap biosensors made of gold and fabricated through standard photolithography combined with focused ion beam lithography. The nano-gap walls are covalently modified with short, anti-symmetric thiolated DNA probes, which are terminated by 19 bases complementary to both the ends of a target DNA strand. The nano-gaps are separated by a distance of 50nm, which was adjusted to fit the length of the DNA target plus the DNA probes. The hybridization of the target DNA closes the gap circuit in a switch on/off fashion, in such a way that it is readily detected by an increase in the current after nano-gap closure. The nano-biosensor shows high specificity in the discrimination of base-pair mismatching and does not require signal indicators or enhancing molecules. The design of the biosensor platform is applicable for multiplexed detection in a straightforward manner. The platform is well-suited to mass production, point-of-care diagnostics, and wide-scale DNA analysis applications. (paper)

Large-area laser nano-texturing with user-defined patterns

International Nuclear Information System (INIS)

Li, L; Guo, W; Wang, Z B; Whitehead, D; Liu, Z; Luk'yanchuk, B

2009-01-01

Writing nano-sized features less than the diffraction limit of the lasers efficiently over a large area requires special technology development. This paper reports the use of a self-assembled particle lens array with near-field enhancement effect to write millions of nano-sized user-defined features, e.g. English letters, lines, curves, simultaneously by angular beam scanning. About a 5 mm × 5 mm area can be written with a single shot of a laser beam or few scans for up to 100 million identical features of nano or sub-micro scales. With the help of certain environmental conditions, such as the use of a suitable chemical solution in conjunction with the particle lens array, the characteristic of the features produced can be further controlled, including the generation of reversed (e.g. pits become hills and grooves become walls) features of laser-written patterns. The technical challenges, experimental findings and theoretical analysis/simulation are presented

Adenyl cyclases and cAMP in plant signaling - Past and present

KAUST Repository

Gehring, Christoph A.

2010-06-25

In lower eukaryotes and animals 3\\'-5\\'-cyclic adenosine monophosphate (cAMP) and adenyl cyclases (ACs), enzymes that catalyse the formation of cAMP from ATP, have long been established as key components and second messengers in many signaling pathways. In contrast, in plants, both the presence and biological role of cAMP have been a matter of ongoing debate and some controversy. Here we shall focus firstly on the discovery of cellular cAMP in plants and evidence for a role of this second messenger in plant signal transduction. Secondly, we shall review current evidence of plant ACs, analyse aspects of their domain organisations and the biological roles of candidate molecules. In addition, we shall assess different approaches based on search motifs consisting of functionally assigned amino acids in the catalytic centre of annotated and/or experimentally tested nucleotide cyclases that can contribute to the identification of novel candidate molecules with AC activity such as F-box and TIR proteins. 2010 Gehring; licensee BioMed Central Ltd.

Adenyl cyclases and cAMP in plant signaling - Past and present

KAUST Repository

Gehring, Christoph A

2010-01-01

In lower eukaryotes and animals 3'-5'-cyclic adenosine monophosphate (cAMP) and adenyl cyclases (ACs), enzymes that catalyse the formation of cAMP from ATP, have long been established as key components and second messengers in many signaling pathways. In contrast, in plants, both the presence and biological role of cAMP have been a matter of ongoing debate and some controversy. Here we shall focus firstly on the discovery of cellular cAMP in plants and evidence for a role of this second messenger in plant signal transduction. Secondly, we shall review current evidence of plant ACs, analyse aspects of their domain organisations and the biological roles of candidate molecules. In addition, we shall assess different approaches based on search motifs consisting of functionally assigned amino acids in the catalytic centre of annotated and/or experimentally tested nucleotide cyclases that can contribute to the identification of novel candidate molecules with AC activity such as F-box and TIR proteins. 2010 Gehring; licensee BioMed Central Ltd.

Understanding cAMP-dependent allostery by NMR spectroscopy: comparative analysis of the EPAC1 cAMP-binding domain in its apo and cAMP-bound states.

Science.gov (United States)

Mazhab-Jafari, Mohammad T; Das, Rahul; Fotheringham, Steven A; SilDas, Soumita; Chowdhury, Somenath; Melacini, Giuseppe

2007-11-21

cAMP (adenosine 3',5'-cyclic monophosphate) is a ubiquitous second messenger that activates a multitude of essential cellular responses. Two key receptors for cAMP in eukaryotes are protein kinase A (PKA) and the exchange protein directly activated by cAMP (EPAC), which is a recently discovered guanine nucleotide exchange factor (GEF) for the small GTPases Rap1 and Rap2. Previous attempts to investigate the mechanism of allosteric activation of eukaryotic cAMP-binding domains (CBDs) at atomic or residue resolution have been hampered by the instability of the apo form, which requires the use of mixed apo/holo systems, that have provided only a partial picture of the CBD apo state and of the allosteric networks controlled by cAMP. Here, we show that, unlike other eukaryotic CBDs, both apo and cAMP-bound states of the EPAC1 CBD are stable under our experimental conditions, providing a unique opportunity to define at an unprecedented level of detail the allosteric interactions linking two critical functional sites of this CBD. These are the phosphate binding cassette (PBC), where cAMP binds, and the N-terminal helical bundle (NTHB), which is the site of the inhibitory interactions between the regulatory and catalytic regions of EPAC. Specifically, the combined analysis of the cAMP-dependent changes in chemical shifts, 2 degrees structure probabilities, hydrogen/hydrogen exchange (H/H) and hydrogen/deuterium exchange (H/D) protection factors reveals that the long-range communication between the PBC and the NTHB is implemented by two distinct intramolecular cAMP-signaling pathways, respectively, mediated by the beta2-beta3 loop and the alpha6 helix. Docking of cAMP into the PBC perturbs the NTHB inner core packing and the helical probabilities of selected NTHB residues. The proposed model is consistent with the allosteric role previously hypothesized for L273 and F300 based on site-directed mutagenesis; however, our data show that such a contact is part of a

Three-dimensional fabrication and characterisation of core-shell nano-columns using electron beam patterning of Ge-doped SiO2

DEFF Research Database (Denmark)

Gontard, Lionel C.; Jinschek, Joerg R.; Ou, Haiyan

2012-01-01

electron tomography. The results show that transformations in insulators that have been subjected to intense irradiation using charged particles can be studied directly in three dimensions. The fabricated structures include core-shell nano-columns, sputtered regions, voids, and clusters. (C) 2012 American......A focused electron beam in a scanning transmission electron microscope (STEM) is used to create arrays of core-shell structures in a specimen of amorphous SiO2 doped with Ge. The same electron microscope is then used to measure the changes that occurred in the specimen in three dimensions using...

High current relativistic beam propagates stably in gas surrounded by nonconducting walls

International Nuclear Information System (INIS)

Clark, J.C.

1977-01-01

LLL has been studying the propagation of high current electron beams for a number of years to understand their behavior for use in a variety of experimental uses. Our latest experiments have shown that a mildly relativistic electron beam of 10 to 15 kA and a pulse width of 30 to 40 ns can propagate stably and with no net current transfer in insulating tubes filled with neutral gases. These experiments have been performed in the Magnetic Fusion Energy program where Electronics Engineering has been operating an electron beam accelerator, designing some of the diagnostics, such as laser interferometers, and performing the experiments. This article briefly describes our experimental observations

Activity of cAMP-dependent protein kinases and cAMP-binding proteins of rat kidney cytosol during dehydration

International Nuclear Information System (INIS)

Zelenina, M.N.; Solenov, E.I.; Ivanova, L.N.

1985-01-01

The activity of cAMP-dependent protein kinases, the binding of cAMP, and the spectrum of cAMP-binding proteins in the cytosol of the renal papilla was studied in intact rats and in rats after 24 h on a water-deprived diet. It was found that the activation of protein kinases by 10 -6 M cAMP is significantly higher in the experimental animals than in the intact animals. In chromatography on DEAE-cellulose, the positions of the peaks of specific reception of cAMP corresponded to the peaks of the regulatory subunits of cAMP-dependent protein kinases of types I and II. In this case, in intact animals more than 80% of the binding activity was detected in peaks II, whereas in rats subjected to water deprivation, more than 60% of the binding was observed in peak I. The general regulatory activity of the cytosol was unchanged in the experimental animals in comparison with intact animals. It is suggested that during dehydration there is an induction of the synthesis of the regulatory subunit of type I cAMP-dependent protein kinase in the renal papilla

Progress of neutral beam R and D for plasma heating and current drive at JAERI

International Nuclear Information System (INIS)

Ohara, Y.

1995-01-01

Recent progress and future plans regarding development of a high power negative ion source at the Japan Atomic Energy Research Institute (JAERI) are described. The neutral beam injection system, which is expected to play an important role not only in plasma heating but also in the plasma current drive in the fusion reactor, requires a high power negative ion source which can produce negative deuterium ion beams with current of order 20A at energy above 1MeV. In order to realize such a high power negative ion beam, intensive research and development has been carried out at JAERI since 1984. The negative hydrogen ion beam current of 10A achieved in recent years almost equals the value required for the fusion reactor. With regard to the negative ion acceleration, a high current negative ion beam of 0.2A has been accelerated up to 350keV electrostatically. On the basis of this recent progress, two development plans have been initiated as an intermediate step towards the fusion reactor. One is to develop a 500keV, 10MW negative ion based neutral beam injection system for JT-60U to demonstrate the neutral beam current drive in a high density plasma. The other is to develop a 1MeV, 1A ion source to demonstrate high current negative ion acceleration up to 1MeV. On the basis of this research and development, an efficient and reactor relevant neutral beam injection system will be developed for an experimental fusion reactor such as the International Thermonuclear Experimental Reactor. ((orig.))

High beam current shut-off systems in the APS linac and low energy transfer line

International Nuclear Information System (INIS)

Wang, X.; Knott, M.; Lumpkin, A.

1994-01-01

Two independent high beam current shut-off current monitoring systems (BESOCM) have been installed in the APS linac and the low energy transport line to provide personnel safety protection in the event of acceleration of excessive beam currents. Beam current is monitored by a fast current transformer (FCT) and fully redundant supervisory circuits connected to the Access Control Interlock System (ACIS) for beam intensity related shutdowns of the linac. One FCT is located at the end of the positron linac and the other in the low energy transport line, which directs beam to the positron accumulator ring (PAR). To ensure a high degree of reliability, both systems employ a continuous self-checking function, which injects a test pulse to a single-turn test winding after each ''real'' beam pulse to verify that the system is fully functional. The system is designed to be fail-safe for all possible system faults, such as loss of power, open or shorted signal or test cables, loss of external trigger, malfunction of gated integrator, etc. The system has been successfully commissioned and is now a reliable part of the total ACIS

WAVEGUIDE COUPLER KICK TO BEAM BUNCH AND CURRENT DEPENDENCY ON SRF CAVITIES

International Nuclear Information System (INIS)

Genfa Wu; Haipeng Wang; Charles Reece; Robert Rimmer

2008-01-01

JLAB SRF cavities employ waveguide type fundamental power couplers (FPC). The FPC design for the 7-cell upgrade cavities was optimized to minimize the dipole field kick. For continuous wave (CW) operation, the forwarding RF power will be at different magnitude to drive the different beam current and cavity gradient. This introduces some deviation from optimized FPC field for varying beam loading. This article analyzes the beam behavior both in centroid kick and head-tail kick under different beam loading conditions

Nano-structural characteristics and optical properties of silver chiral nano-flower sculptured thin films

Energy Technology Data Exchange (ETDEWEB)

Savaloni, Hadi, E-mail: savaloni@khayam.ut.ac.ir [Department of Physics, University of Tehran, North-Kargar Street, Tehran (Iran, Islamic Republic of); Haydari-Nasab, Fatemh; Malmir, Mariam [Department of Physics, University of Tehran, North-Kargar Street, Tehran (Iran, Islamic Republic of)

2011-08-15

Silver chiral nano-flowers with 3-, 4- and 5-fold symmetry were produced using oblique angle deposition method in conjunction with the rotation of sample holder with different speeds at different sectors of each revolution corresponding to symmetry order of the acquired nano-flower. Atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM), were employed to obtain morphology and nano-structure of the films. Optical characteristics of silver chiral nano-flower thin films were obtained using single beam spectrophotometer with both s- and p-polarization incident light at 30{sup o} and 70{sup o} incidence angles and at different azimuthal angles ({phi}). Optical spectra showed both TM (TDM (transverse dipole mode) and TQM (transverse quadruple mode)) and LM (longitudinal mode) Plasmon resonance peaks. For 3- and 4-fold symmetry chiral nano-flowers the s-polarization extinction spectra obtained at different azimuthal angles did not show significant change in the Plasmon peak position while 5-fold symmetry chiral nano-flower showed a completely different behavior, which may be the result of increased surface anisotropy, so when the {phi} angle is changed the s-polarization response from the surface can change more significantly than that for lower symmetries. In general, for 3-, 4- and 5-fold symmetry chiral nano-flowers a sharp peak at lower wavelengths (<450 nm) is observed in the s-polarization spectra, while in addition to this peak a broad peak at longer wavelengths (i.e., LM) observed in the p-polarization spectra, which is more dominant for 70{sup o} incidence angle.

Purification, characterization, and sequencing of novel antimicrobial peptides, Tu-AMP 1 and Tu-AMP 2, from bulbs of tulip (Tulipa gesneriana L.).

Science.gov (United States)

Fujimura, Masatoshi; Ideguchi, Mineo; Minami, Yuji; Watanabe, Keiichi; Tadera, Kenjiro

2004-03-01

Novel antimicrobial peptides (AMP), designated Tu-AMP 1 and Tu-AMP 2, were purified from the bulbs of tulip (Tulipa gesneriana L.) by chitin affinity chromatography and reverse-phase high-performance liquid chromatography (HPLC). They bind to chitin in a reversible way. They were basic peptides having isoelectric points of over 12. Tu-AMP 1 and Tu-AMP 2 had molecular masses of 4,988 Da and 5,006 Da on MALDI-TOF MS analysis, and their extinction coefficients of 1% aqueous solutions at 280 nm were 3.3 and 3.4, respectively. Half of all amino acid residues of Tu-AMP 1 and Tu-AMP 2 were occupied by cysteine, arginine, lysine, and proline. The concentrations of peptides required for 50% inhibition (IC(50)) of the growth of plant pathogenic bacteria and fungi were 2 to 20 microg/ml. The structural characteristics of Tu-AMP 1 and Tu-AMP 2 indicated that they were novel thionin-like antimicrobial peptides, though Tu-AMP 2 was a heterodimer composes of two short peptides joined with disulfide bonds.

Applications and Nano toxicity of Carbon Nano tubes and Graphene in Biomedicine Caitlin Fisher

International Nuclear Information System (INIS)

Rider, A.E.; Han, Z.J.; Kumar, S.; Levchenko, L.; Ostrikov, K.K.

2012-01-01

Owing to their unique mechanical, electrical, optical, and thermal properties, carbon nano structures including carbon nano tubes and graphenes show great promise for advancing the fields of biology and medicine. Many reports have demonstrated the promise of these carbon nano structures and their hybrid structures (composites with polymers, ceramics, and metal nanoparticles, etc.) for a variety of biomedical areas ranging from bio sensing, drug delivery, and diagnostics, to cancer treatment, tissue engineering, and bio terrorism prevention. However, the issue of the safety and toxicity of these carbon nano structures, which is vital to their use as diagnostic and therapeutic tools in biomedical fields, has not been completely resolved. This paper aims to provide a summary of the features of carbon nano tube and graphene-based materials and current research progress in biomedical applications. We also highlight the current opinions within the scientific community on the toxicity and safety of these carbon structures

Limiting currents of an unneutralized magnetized electron beam in a cylindrical drift tube

International Nuclear Information System (INIS)

Thompson, J.R.; Sloan, M.L.

1978-01-01

Results of an investigation of the steady state injection of a uniform unneutralized, magnetized, relativistic electron beam into a cylindrical drift tube are presented. The space-charge-limited current and the asymptotic kinetic energy of electrons on axis is determined both numerically and analytically as a function of the input kinetic energy (γ 0 -1) mc 2 and of the ratio of beam-to-wall radii. A previously cited ''interpolation formula'' is obtained in the pencil beam limit, but more accurate limiting current expressions are developed for other cases (such as the fat beam limit) where the interpolation formula is as much as 20% in error. The corresponding axial electron energy is also found to be significantly smaller than the previously cited value of (γ/sup 1/3/ 0 -1) mc 2 except in the strong pencil beam limit

Is it viable to improve light output efficiency by nano-light-emitting diodes?

Energy Technology Data Exchange (ETDEWEB)

Wang, Chao-Hung; Huang, Yu-Wen [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Wu, Shang-En [Genesis Photonics Incorporation, Tainan 70101, Taiwan (China); Liu, Chuan-Pu, E-mail: cpliu@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 70101, Taiwan (China); Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 70101, Taiwan (China)

2013-12-02

Nanopillar arrays with InGaN/GaN multiple-quantum-disks (MQDs) are fabricated by focused-ion-beam milling with surface damage layer removed by KOH wet etching. Nano-light-emitting diodes (Nano-LEDs) made of the InGaN/GaN MQD nanopillars are found to have 19.49% less output power than that of a conventional LED. The reasons are analyzed in detail and considering their current-voltage and electroluminescence characteristics, internal quantum efficiency, external quantum efficiency, light extraction, and wall-plug efficiency. Our results suggest that nanopillar-LED can outperform if the density can be increased to 2.81 × 10{sup 9} cm{sup −2} with the size unchanged or the size can be increased to 854.4 nm with the density unchanged.

Optical fiber Cherenkov detector for beam current monitoring

International Nuclear Information System (INIS)

Pishchulin, I.V.; Solov'ev, N.G.; Romashkin, O.B.

1991-01-01

The results obtained in calculation of an optical fiber Cherenkov detector for accelerated beam current monitoring are presented. The technique of beam parameters monitoring is based on Cherenkov radiation excitation by accelerated electrons in the optical fiber. The formulas for calculations of optical power and time dependence of Cherenkov radiation pulse are given. The detector sensitivity and time resolution dependence on the fiber material characteristics are investigated. Parameters of a 10μm one-mode quartz optical fiber detector for the free electron laser photoinjector are calculated. The structure of a monitoring system with the optical fiber Cherenkov detector is considered. Possible applications of this technique are discussed and some recommendations are given

Open-loop correction for an eddy current dominated beam-switching magnet.

Science.gov (United States)

Koseki, K; Nakayama, H; Tawada, M

2014-04-01

A beam-switching magnet and the pulsed power supply it requires have been developed for the Japan Proton Accelerator Research Complex. To switch bunched proton beams, the dipole magnetic field must reach its maximum value within 40 ms. In addition, the field flatness should be less than 5 × 10(-4) to guide each bunched beam to the designed orbit. From a magnetic field measurement by using a long search coil, it was found that an eddy current in the thick endplates and laminated core disturbs the rise of the magnetic field. The eddy current also deteriorates the field flatness over the required flat-top period. The measured field flatness was 5 × 10(-3). By using a double-exponential equation to approximate the measured magnetic field, a compensation pattern for the eddy current was calculated. The integrated magnetic field was measured while using the newly developed open-loop compensation system. A field flatness of less than 5 × 10(-4), which is an acceptable value, was achieved.

Functional desensitization to isoproterenol without reducing cAMP production in canine failing cardiocytes.

Science.gov (United States)

Laurent, C E; Cardinal, R; Rousseau, G; Vermeulen, M; Bouchard, C; Wilkinson, M; Armour, J A; Bouvier, M

2001-02-01

To corroborate alterations in the functional responses to beta-adrenergic receptor (beta-AR) stimulation with changes in beta-AR signaling in failing cardiomyocytes, contractile and L-type Ca(2+) current responses to isoproterenol along with stimulated cAMP generation were compared among cardiomyocytes isolated from canines with tachycardia-induced heart failure or healthy hearts. The magnitude of shortening of failing cardiomyocytes was significantly depressed (by 22 +/- 4.4%) under basal conditions, and the maximal response to isoproterenol was significantly reduced (by 45 +/- 18%). Similar results were obtained when the responses in the rate of contraction and rate of relaxation to isoproterenol were considered. The L-type Ca(2+) current amplitude measured in failing cardiomyocytes under basal conditions was unchanged, but the responses to isoproterenol were significantly reduced compared with healthy cells. Isoproterenol-stimulated cAMP generation was similar in sarcolemmal membranes derived from the homogenates of failing (45 +/- 6.8) and healthy cardiomyocytes (52 +/- 8.5 pmol cAMP. mg protein(-1). min(-1)). However, stimulated cAMP generation was found to be significantly reduced when the membranes were derived from the homogenates of whole tissue (failing: 67 +/- 8.1 vs. healthy: 140 +/- 27.8 pmol cAMP. mg protein(-1). min(-1)). Total beta-AR density was not reduced in membranes derived from either whole tissue or isolated cardiomyocyte homogenates, but the beta(1)/beta(2) ratio was significantly reduced in the former (failing: 45/55 vs. healthy: 72/28) without being altered in the latter (failing: 72/28, healthy: 77/23). We thus conclude that, in tachycardia-induced heart failure, reduction in the functional responses of isolated cardiomyocytes to beta-AR stimulation may be attributed to alterations in the excitation-contraction machinery rather than to limitation of cAMP generation.

Nano-resonator frequency response based on strain gradient theory

International Nuclear Information System (INIS)

Miandoab, Ehsan Maani; Yousefi-Koma, Aghil; Pishkenari, Hossein Nejat; Fathi, Mohammad

2014-01-01

This paper aims to explore the dynamic behaviour of a nano-resonator under ac and dc excitation using strain gradient theory. To achieve this goal, the partial differential equation of nano-beam vibration is first converted to an ordinary differential equation by the Galerkin projection method and the lumped model is derived. Lumped parameters of the nano-resonator, such as linear and nonlinear springs and damper coefficients, are compared with those of classical theory and it is demonstrated that beams with smaller thickness display greater deviation from classical parameters. Stable and unstable equilibrium points based on classic and non-classical theories are also compared. The results show that, regarding the applied dc voltage, the dynamic behaviours expected by classical and non-classical theories are significantly different, such that one theory predicts the un-deformed shape as the stable condition, while the other theory predicts that the beam will experience bi-stability. To obtain the frequency response of the nano-resonator, a general equation including cubic and quadratic nonlinearities in addition to parametric electrostatic excitation terms is derived, and the analytical solution is determined using a second-order multiple scales method. Based on frequency response analysis, the softening and hardening effects given by two theories are investigated and compared, and it is observed that neglecting the size effect can lead to two completely different predictions in the dynamic behaviour of the resonators. The findings of this article can be helpful in the design and characterization of the size-dependent dynamic behaviour of resonators on small scales. (paper)

Macrofilament simulation of high current beam transport

International Nuclear Information System (INIS)

Hayden, R.J.; Jakobson, M.J.

1985-01-01

Macrofilament simulation of high current beam transport through a series of solenoids has been used to investigate the sensitivity of such calculations to the initial beam distribution and to the number of filaments used in the simulation. The transport line was tuned to approximately 105 0 phase advance per cell at zero current with a tune depression of 65 0 due to the space charge. Input distributions with the filaments randomly uniform throughout a four dimensional ellipsoid and K-V input distributions have been studied. The behavior of the emittance is similar to that published for quadrupoles with like tune depression. The emittance demonstrated little growth in the first twelve solenoids, a rapid rate of growth for the next twenty, and a subsequent slow rate of growth. A few hundred filaments were sufficient to show the character of the instability. The number of filaments utilized is an order of magnitude fewer than has been utilized previously for similar instabilities. The previously published curves for simulations with less than a thousand particles show a rather constant emittance growth. If the solenoid transport line magnetic field is increased a few percent, emittance growth curves are obtained not unlike those curves. Collision growth effects are less important than indicated in the previously published results for quadrupoles

Supersonic cluster beams: a powerful method for the deposition of nanostructured thin films with tailored properties

International Nuclear Information System (INIS)

Milani, P.

2002-01-01

By using a pulsed micro-plasma cluster source and by exploiting aero-dynamical effects typical of supersonic beams it is possible to obtain very high deposition rates with a control on neutral cluster mass distribution, allowing the deposition of thin films with controlled nanostructure. Due to high deposition rates, high lateral resolution, low temperature processing supersonic cluster beams can also be used for the micro and nano-patterning of cluster-assembled films when little or no post-growth manipulation or assembly is required. For example the nano and meso-structure of films obtained by carbon cluster beam deposition can be controlled by selecting in the beam the elemental building blocks, moreover functional properties such as field emission can be controlled and tailored. The use of supersonic cluster beams opens also new perspectives for the production of nano-structured films with novel physico-chemical and topological properties such as nano-structured carbon matrices containing carbide and transition metal particles. (Author)

Novel Faraday cup for the simultaneous observation and measurement of ion-beam currents

International Nuclear Information System (INIS)

Wei, C.; Seidman, D.N.

1977-01-01

A novel Faraday cup is described which allows the simultaneous observation and measurement of ion-beam currents. The Faraday cup is constructed around a Galileo channel electron multiplier array (CEMA), which serves as the basis of an internal image intensification system (a gain of >10 4 ) for the observation of the ion beam; the CEMA also acts as a collector for the ion current which is measured by a Keithley 602 electrometer. The ion current is integrated by a simple and inexpensive dosimeter; the electronic circuit for the dosimeter is described. The application of the Faraday cup to the observation and measurement of a 30-keV Ar + ion beam is presented as an illustrative example. We have also employed this Faraday cup to observe and measure 30-keV Cr + , Mo + , or W + , and 18-keV Au + ion beams employed for the in situ irradiation of field-ion microscope specimens

Image analysis of the nano DDS using photon radiation in SPring-8

International Nuclear Information System (INIS)

Noda, Nobuo; Koide, Kazuharu; Nemoto, Tetsuya; Matsuura, Hiroyuki; Makino, Ken-ichi; Nakano, Masahiro; Ju, Dong-Ying; Bian, Pei

2007-01-01

Recently, technology to handle a molecule of nano scale advances, and an applied technology is developed in every area. Development of nano-drug delivery system (DDS) is performed worldwide in the med-tech area. We try the effectiveness of nano-DDS. The dynamic behavior of nano-scale magnet in biomaterials is not well known. Therefore it is necessary we perform direct observation, and to get information of the behavior. Using strong photon beams in Spring-8 facility, we trace the magnets and investigate the leaf or the egg. (author)

Electron beam dynamics in the long-pulse, high-current DARHT-II linear induction accelerator

International Nuclear Information System (INIS)

Ekdahl, Carl A.; Abeyta, Epifanio O.; Aragon, Paul; Archuleta, Rita; Cook, Gerald; Dalmas, Dale; Esquibel, Kevin; Gallegos, Robert A.; Garnett, Robert; Harrison, James F.; Johnson, Jeffrey B.; Jacquez, Edward B.; Mccuistian, Brian T.; Montoya, Nicholas A.; Nath, Subrato; Nielsen, Kurt; Oro, David; Prichard, Benjamin; Rowton, Lawrence; Sanchez, Manolito; Scarpetti, Raymond; Schauer, Martin M.; Seitz, Gerald; Schulze, Martin; Bender, Howard A.; Broste, William B.; Carlson, Carl A.; Frayer, Daniel K.; Johnson, Douglas E.; Tom, C.Y.; Williams, John; Hughes, Thomas; Anaya, Richard; Caporaso, George; Chambers, Frank; Chen, Yu-Jiuan; Falabella, Steve; Guethlein, Gary; Raymond, Brett; Richardson, Roger; Trainham, C.; Watson, Jim; Weir, John; Genoni, Thomas; Toma, Carsten

2009-01-01

The DARHT-II linear induction accelerator (LIA) now accelerates 2-kA electron beams to more than 17 MeV. This LIA is unique in that the accelerated current pulse width is greater than 2 microseconds. This pulse has a flat-top region where the final electron kinetic energy varies by less than 1% for more than 1.5 microseconds. The long risetime of the 6-cell injector current pulse is 0.5 (micro)s, which can be scraped off in a beam-head cleanup zone before entering the 68-cell main accelerator. We discuss our experience with tuning this novel accelerator; and present data for the resulting beam transport and dynamics. We also present beam stability data, and relate these to previous stability experiments at lower current and energy.

Applicability evaluation of eddy current testing for underwater laser beam welding

International Nuclear Information System (INIS)

Kobayashi, Noriyasu; Kasuya, Takashi; Ueno, Souichi; Ochiai, Makoto; Yuguchi, Yasuhiro

2010-01-01

We clarified a defect detecting capability of eddy current testing (ECT) as a surface inspection technique for underwater laser beam welding. An underwater laser beam welding procedure includes groove caving as a preparation, laser beam welding in groove and welding surface grinding as a post treatment. Therefore groove and grinded welding surface inspections are required underwater. We curried out defect detection tests using three kinds of specimens simulated a groove, reactor vessel nozzle dissimilar metal welding materials and a laser beam welding material with a cross coil ECT probe. From experimental results, we confirmed that it is possible to detect 0.3 mm or more depth electro-discharge machining slits on machining surfaces in all specimens and an ECT has possibility as a surface inspection technique for underwater laser beam welding. (author)

Introduction of Functional Structures in Nano-Scales into Engineering Polymer Films Using Radiation Technique

Energy Technology Data Exchange (ETDEWEB)

Maekawa, Y., E-mail: maekawa.yasunari@jaea.go.jp [Japan Atomic Energy Agency (JAEA), Quantum Beam Science Directorate, High Performance Polymer Group, 1233 Watanuki-Machi, Takasaki, Gunma-ken 370-1292 (Japan)

2010-07-01

Introduction of functional regions in nanometer scale in polymeric films using γ-rays, EB, and ion beams are proposed. Two approaches to build nano-scale functional domains in polymer substrates are proposed: 1) Radiation-induced grafting to transfer nano-scale polymer crystalline structures (morphology), acting as a nano-template, to nano-scale graft polymer regions. The obtained polymers with nano structures can be applied to high performance polymer membranes. 2) Fabrication of nanopores and functional domains in engineering plastic films using ion beams, which deposit the energy in very narrow region of polymer films. Hydrophilic grafting polymers are introduced into hydrophobic fluorinated polymers, cross-linked PTFE (cPTFE) and aromatic hydrocarbon polymer, poly(ether ether ketone (PEEK), which is known to have lamella and crystallite in the polymer films. Then, the hierarchical structures of graft domains are analyzed by a small angle neutron scattering (SANS) experiment. From these analyses, the different structures and the different formation of graft domains were observed in fluorinated and hydrocarbon polymer substrates. the grafted domains in the cPTFE film, working as an ion channel, grew as covering the crystallite and the size of domain seems to be similar to that of crystallite. On the other hand, the PEEK-based PEM has a smaller domain size and it seems to grow independently on the crystallites of PEEK substrate. For nano-fabrication of polymer films using heavy ion beams, the energy distribution in radial direction, which is perpendicular to ion trajectory, is mainly concerned. For penumbra, we re-estimated effective radius of penumbra, in which radiation induced grafting took place, for several different ion beams. We observed the different diameters of the ion channels consisting of graft polymers. The channel sizes were quite in good agreement with the effective penumbra which possess the absorption doses more than 1 kGy. (author)

Introduction of Functional Structures in Nano-Scales into Engineering Polymer Films Using Radiation Technique

International Nuclear Information System (INIS)

Maekawa, Y.

2010-01-01

Introduction of functional regions in nanometer scale in polymeric films using γ-rays, EB, and ion beams are proposed. Two approaches to build nano-scale functional domains in polymer substrates are proposed: 1) Radiation-induced grafting to transfer nano-scale polymer crystalline structures (morphology), acting as a nano-template, to nano-scale graft polymer regions. The obtained polymers with nano structures can be applied to high performance polymer membranes. 2) Fabrication of nanopores and functional domains in engineering plastic films using ion beams, which deposit the energy in very narrow region of polymer films. Hydrophilic grafting polymers are introduced into hydrophobic fluorinated polymers, cross-linked PTFE (cPTFE) and aromatic hydrocarbon polymer, poly(ether ether ketone (PEEK), which is known to have lamella and crystallite in the polymer films. Then, the hierarchical structures of graft domains are analyzed by a small angle neutron scattering (SANS) experiment. From these analyses, the different structures and the different formation of graft domains were observed in fluorinated and hydrocarbon polymer substrates. the grafted domains in the cPTFE film, working as an ion channel, grew as covering the crystallite and the size of domain seems to be similar to that of crystallite. On the other hand, the PEEK-based PEM has a smaller domain size and it seems to grow independently on the crystallites of PEEK substrate. For nano-fabrication of polymer films using heavy ion beams, the energy distribution in radial direction, which is perpendicular to ion trajectory, is mainly concerned. For penumbra, we re-estimated effective radius of penumbra, in which radiation induced grafting took place, for several different ion beams. We observed the different diameters of the ion channels consisting of graft polymers. The channel sizes were quite in good agreement with the effective penumbra which possess the absorption doses more than 1 kGy. (author)

Small-sized monitor of beam current and profile for the proton pulse electrostatic accelerator

International Nuclear Information System (INIS)

Getmanov, V.N.

1985-01-01

Design and principle of operation of current monitor and beam profile of range-coordinate type are described. Monitor operation peculiarities are discussed using diagnostics of a beam of 330-420 keV electrostatic pulse proton accelerator with a beam current of up to 20 mA, at a current density of up to 23 mA x cm -2 and wth pulse duraton of about 20 μs. The monitor consists of a vacuum-dense foil of 3.0+-0.1 μm in thickness (or 0.81+-0.0x- mg x cm -2 ) two grid electrodes, each containing 12 wires, and as solid copper bottom. Foil serves for chopping off background particles with a path lesser 3.0 μm and stands thermal pulse load up to 0.5 J/cm -2 . Grid electrode wires are oriented perpendicularly to lach other and form a two-coordinate secondary-emisson roughness indicator. The bothhom is used for measuring an absolute value of beam current

Calcium pathways such as cAMP modulate clothianidin action through activation of α-bungarotoxin-sensitive and -insensitive nicotinic acetylcholine receptors.

Science.gov (United States)

Calas-List, Delphine; List, Olivier; Quinchard, Sophie; Thany, Steeve H

2013-07-01

Clothianidin is a neonicotinoid insecticide developed in the early 2000s. We have recently demonstrated that it was a full agonist of α-bungarotoxin-sensitive and -insensitive nicotinic acetylcholine receptors expressed in the cockroach dorsal unpaired median neurons. Clothianidin was able to act as an agonist of imidacloprid-insensitive nAChR2 receptor and internal regulation of cAMP concentration modulated nAChR2 sensitivity to clothianidin. In the present study, we demonstrated that cAMP modulated the agonist action of clothianidin via α-bungarotoxin-sensitive and insensitive receptors. Clothianidin-induced current-voltage curves were dependent to clothianidin concentrations. At 10 μM clothianidin, increasing cAMP concentration induced a linear current-voltage curve. Clothianidin effects were blocked by 0.5 μM α-bungarotoxin suggesting that cAMP modulation occurred through α-bungarotoxin-sensitive receptors. At 1 mM clothianidin, cAMP effects were associated to α-bungarotoxin-insensitive receptors because clothianidin-induced currents were blocked by 5 μM mecamylamine and 20 μM d-tubocurarine. In addition, we found that application of 1mM clothianidin induced a strong increase of intracellular calcium concentration. These data reinforced the finding that calcium pathways including cAMP modulated clothianidin action on insect nicotinic acetylcholine receptors. We proposed that intracellular calcium pathways such as cAMP could be a target to modulate the mode of action of neonicotinoid insecticides. Copyright © 2013 Elsevier Inc. All rights reserved.

21 CFR 862.1230 - Cyclic AMP test system.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cyclic AMP test system. 862.1230 Section 862.1230....1230 Cyclic AMP test system. (a) Identification. A cyclic AMP test system is a device intended to measure the level of adenosine 3′, 5′-monophosphate (cyclic AMP) in plasma, urine, and other body fluids...

Oriented nano-wire formation and selective adhesion on substrates by single ion track reaction in polysilanes

International Nuclear Information System (INIS)

Shu Seki; Satoshi Tsukuda, Yoichi Yoshida; Seiichi Tagawa; Masaki Sugimoto; Shigeru Tanaka

2002-01-01

1-D nano-sized materials such as carbon nanotubes have attracted much attention as ideal quantum wires for future manufacturing techniques of nano-scaled opto-electronic devices. However it is still difficult to control the sizes, spatial distributions, or positions of nanotubes by conventional synthetic techniques to date. The MeV order heavy ion beams causes ultra-high density energy deposition which can not be realized by any other techniques (lasers, H, etc), and penetrate the polymer target straighforward as long as 1∼100 m depth. the energy deposited area produces non-homogeneous field can be controlled by changing the energy deposition rate of incident ions (LET: linear energy transfer, eV/nm). We found that cross-linking reaction of polysilane derivatives was predominantly caused and gave nano-gel in the chemical core, unlike main chain scission occurring at the outside of the area. high density energy deposition by ion beams causes non-homogeneous crosslinking reaction of polysilane derivatives within a nano-sized cylindrical area along an ion trajectory, and gives -SiC based nano-wires of which sizes (length, thickness) and number densities are completely under control by changing the parameters of incident ion beams and molecular sizes of target polymers. based on the concept pf the single track gelation, the present study demonstrates the formation of cross-linked polysilane nano-wires with the fairly controlled sizes. Recently the techniques of position-selective single ion hitting have been developed for MeV order ion beams, however it is not sufficient to control precisely the positions of the nano-wires on the substrates within sub- m area. in the present study, we report the selective adhesion of anno-wires on Si substrates by the surface treatments before coating, which enables the patterning of planted nano-wires on substrates and/or electrodes as candidates for nano-sized field emissive cathodes or electro-luminescent devices. Some examples of

Sintering characteristics of nano-ceramic coatings

NARCIS (Netherlands)

de Hosson, J.T.M.; Popma, R.

2003-01-01

This paper concentrates on sintering characteristics of nano-sized ceramic SiO2 particles. The sintering process is studied as a function of temperature using a conventional furnace and using a laser beam. The underlying idea is to combine the nanoceramic sol-gel concept with inkjet technology and

In situ beam angle measurement in a multi-wafer high current ion implanter

International Nuclear Information System (INIS)

Freer, B.S.; Reece, R.N.; Graf, M.A.; Parrill, T.; Polner, D.

2005-01-01

Direct, in situ measurement of the average angle and angular content of an ion beam in a multi-wafer ion implanter is reported for the first time. A new type of structure and method are described. The structures are located on the spinning disk, allowing precise angular alignment to the wafers. Current that passes through the structures is known to be within a range of angles and is detected behind the disk. By varying the angle of the disk around two axes, beam current versus angle is mapped and the average angle and angular spread are calculated. The average angle measured in this way is found to be consistent with that obtained by other techniques, including beam centroid offset and wafer channeling methods. Average angle of low energy beams, for which it is difficult to use other direct methods, is explored. A 'pencil beam' system is shown to give average angle repeatability of 0.13 deg. (1σ) or less, for two low energy beams under normal tuning variations, even though no effort was made to control the angle

Influence of total beam current on HRTEM image resolution in differentially pumped ETEM with nitrogen gas

International Nuclear Information System (INIS)

Bright, A.N.; Yoshida, K.; Tanaka, N.

2013-01-01

Environmental transmission electron microscopy (ETEM) enables the study of catalytic and other reaction processes as they occur with Angstrom-level resolution. The microscope used is a dedicated ETEM (Titan ETEM, FEI Company) with a differential pumping vacuum system and apertures, allowing aberration corrected high-resolution transmission electron microscopy (HRTEM) imaging to be performed with gas pressures up to 20 mbar in the sample area and with significant advantages over membrane-type E-cell holders. The effect on image resolution of varying the nitrogen gas pressure, electron beam current density and total beam current were measured using information limit (Young's fringes) on a standard cross grating sample and from silicon crystal lattice imaging. As expected, increasing gas pressure causes a decrease in HRTEM image resolution. However, the total electron beam current also causes big changes in the image resolution (lower beam current giving better resolution), whereas varying the beam current density has almost no effect on resolution, a result that has not been reported previously. This behavior is seen even with zero-loss filtered imaging, which we believe shows that the drop in resolution is caused by elastic scattering at gas ions created by the incident electron beam. Suitable conditions for acquiring high resolution images in a gas environment are discussed. Lattice images at nitrogen pressures up to 16 mbar are shown, with 0.12 nm information transfer at 4 mbar. -- Highlights: ► ETEM images with point resolution of 0.12 nm in 4 mbar of nitrogen gas. ► Clear Si lattice imaging with 16 mbar of nitrogen gas. ► ETEM image resolution in gas can be much improved by decreasing total beam current. ► Beam current density (beam convergence) has no effect on the image resolution.

Activation of PKA in cell requires higher concentration of cAMP than in vitro: implications for compartmentalization of cAMP signalling.

Science.gov (United States)

Koschinski, Andreas; Zaccolo, Manuela

2017-10-26

cAMP is a ubiquitous second messenger responsible for the cellular effects of multiple hormones and neurotransmitters via activation of its main effector, protein kinase A (PKA). Multiple studies have shown that the basal concentration of cAMP in several cell types is about 1 μM. This value is well above the reported concentration of cAMP required to half-maximally activate PKA, which measures in the 100-300 nM range. Several hypotheses have been suggested to explain this apparent discrepancy including inaccurate measurements of intracellular free cAMP, inaccurate measurement of the apparent activation constant of PKA or shielding of PKA from bulk cytosolic cAMP via localization of the enzyme to microdomains with lower basal cAMP concentration. However, direct experimental evidence in support of any of these models is limited and a firm conclusion is missing. In this study we use multiple FRET-based reporters for the detection of cAMP and PKA activity in intact cells and we establish that the sensitivity of PKA to cAMP is almost twenty times lower when measured in cell than when measured in vitro. Our findings have important implications for the understanding of compartmentalized cAMP signalling.

Properties of Al2O3 nano-particle reinforced copper matrix composite coatings prepared by pulse and direct current electroplating

International Nuclear Information System (INIS)

Allahkaram, Saeed Reza; Golroh, Setareh; Mohammadalipour, Morteza

2011-01-01

Highlights: → The influence of Al 2 O 3 is studied on morphologies of the DC and PC applied coatings. → The influence of Al 2 O 3 is studied on the DC and PC coating thicknesses. → The influence of Al 2 O 3 is studied on wear resistance. → The effect of Al 2 O 3 is studied on the porosity and corrosion resistance. -- Abstract: Cu-Al 2 O 3 nano-composite coatings have high potential for use in applications in which high mechanical properties together with high corrosion resistance are required. In the present study it is intended to produce copper nano-alumina composite coatings with various nano-alumina contents in order to investigate the effect of alumina reinforcement particles on corrosion resistance and mechanical properties such as hardness and wear resistance. The composite coatings were deposited using direct current (DC) and pulse current (PC) plating. The microstructures of the coatings produced from both methods were examined via scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The wear behaviors, micro hardness, coating thickness, corrosion rate and coating porosity were examined using appropriate methods. Compared to DC deposition, PC plating facilitated higher amounts of particle incorporation with more uniform distribution. The results indicated that the mechanical properties of the applied coatings with incorporated nano-alumina reinforcement were far more superior as compared to its own matrix as well as non-composite copper coatings. It was also found out that increasing the amount of nano-alumina content in the coating, led to enhanced general properties of the coatings.

Scaling for quantum tunneling current in nano- and subnano-scale plasmonic junctions.

Science.gov (United States)

Zhang, Peng

2015-05-19

When two conductors are separated by a sufficiently thin insulator, electrical current can flow between them by quantum tunneling. This paper presents a self-consistent model of tunneling current in a nano- and subnano-meter metal-insulator-metal plasmonic junction, by including the effects of space charge and exchange correlation potential. It is found that the J-V curve of the junction may be divided into three regimes: direct tunneling, field emission, and space-charge-limited regime. In general, the space charge inside the insulator reduces current transfer across the junction, whereas the exchange-correlation potential promotes current transfer. It is shown that these effects may modify the current density by orders of magnitude from the widely used Simmons' formula, which is only accurate for a limited parameter space (insulator thickness > 1 nm and barrier height > 3 eV) in the direct tunneling regime. The proposed self-consistent model may provide a more accurate evaluation of the tunneling current in the other regimes. The effects of anode emission and material properties (i.e. work function of the electrodes, electron affinity and permittivity of the insulator) are examined in detail in various regimes. Our simple model and the general scaling for tunneling current may provide insights to new regimes of quantum plasmonics.

Single-beam measurements of LHC instability threshold in terms of octupole current

CERN Document Server

Mounet, N; Buffat, X; Burov, A; Hemelsoet, G; Metral, E; Papotti, G; Pieloni, T; Pojer, M; Salvant, B; Trad, G

2012-01-01

This note summarizes two machine development (MD) studies aimed at determining the octupole current needed in the LHC in order to stabilize all headtail instabilities at 4TeV/c, before and after the squeeze, with tight collimator settings, and when a single beam (beam 2) at maximum intensity (1380 bunches, 2.1 1014 protons) is present in the machine. The MDs followed the normal physics operation procedure, at the notable exception that a single beam was used, the other beam containing only one non-colliding nominal bunch. Octupole current (with negative polarity in the focusing octupoles and the opposite in the defocusing ones) was decreased by small steps until the instability threshold was reached. This was performed in two distinct MDs, one before the squeeze and the other after it, testing also several chromaticity values and the effect of the transverse damper in the latter case. Octupole thresholds are shown in each case studied, as well as the rise times of the instabilities observed.

Proteomic signatures implicate cAMP in light and temperature responses in Arabidopsis thaliana

KAUST Repository

Thomas, Ludivine

2013-05-01

The second messenger 3\\'-5\\'-cyclic adenosine monophosphate (cAMP) and adenylyl cyclases (ACs), enzymes that catalyse the formation of cAMP from ATP, are increasingly recognized as important signaling molecules in a number of physiological responses in higher plants. Here we used proteomics to identify cAMP-dependent protein signatures in Arabidopsis thaliana and identify a number of differentially expressed proteins with a role in light- and temperature-dependent responses, notably photosystem II subunit P-1, plasma membrane associated cation-binding protein and chaperonin 60 β. Based on these proteomics results we conclude that, much like in cyanobacteria, algae and fungi, cAMP may have a role in light signaling and the regulation of photosynthesis as well as responses to temperature and we speculate that ACs could act as light and/or temperature sensors in higher plants. Biological significance: This current study is significant since it presents the first proteomic response to cAMP, a novel and key second messenger in plants. It will be relevant to researchers in plant physiology and in particular those with an interest in second messengers and their role in biotic and abiotic stress responses. © 2013 Elsevier B.V.

Neutronics design of accelerator-driven system for power flattening and beam current reduction

International Nuclear Information System (INIS)

Nishihara, Kenji; Iwanaga, Kohei; Tsujimoto, Kazufumi; Kurata, Yuji; Oigawa, Hiroyuki; Iwasaki, Tomohiko

2008-01-01

In the present neutronics design of the Accelerator-Driven System (ADS) cooled by lead-bismuth eutectic (LBE), we investigated several methods to reduce the power peak and beam current, and estimated the temperature reductions of the cladding tube and beam window from the conventional design. The methods are adjustment of inert matrix ratio in fuel in each burn-up cycle, multiregion design in terms of pin radius or inert matrix content, and modification of the level of the beam window position and the height of the central fuel assemblies. As a result, we optimized the ADS combined with the adjustment of the inert matrix ratio in each burn-up cycle, multiregion design in terms of inert matrix content and deepened window level. The maximum temperatures of the optimized ADS at the surface of the cladding tube and the beam window were reduced by 91 and 38degC, respectively. The maximum beam current was improved from 20.3 to 15.6 mA. (author)

Preparation, Characterization, and Modeling of Carbon Nano fiber/Epoxy Nano composites

International Nuclear Information System (INIS)

Sun, L.H.; Yang, Z.G.; Ounaies, Z.; Whalen, C.A.; Gao, X.L.

2011-01-01

There is a lack of systematic investigations on both mechanical and electrical properties of carbon nano fiber (CNF)-reinforced epoxy matrix nano composites. In this paper, an in-depth study of both static and dynamic mechanical behaviors and electrical properties of CNF/epoxy nano composites with various contents of CNFs is provided. A modified Halpin-Tsai equation is used to evaluate the Young's modulus and storage modulus of the nano composites. The values of Young's modulus predicted using this method account for the effect of the CNF agglomeration and fit well with those obtained experimentally. The results show that the highest tensile strength is found in the epoxy nano composite with a 1.0 wt % CNFs. The alternate-current (AC) electrical properties of the CNF/epoxy nano composites exhibit a typical insulator-conductor transition. The conductivity increases by four orders of magnitude with the addition of 0.1 wt % (0.058 vol %) CNFs and by ten orders of magnitude for nano composites with CNF volume fractions higher than 1.0 wt % (0.578 vol %). The percolation threshold (i.e., the critical CNF volume fraction) is found to be at 0.057 vol %.

Current control of the electron beam formed in the magnetron gun with a secondary-emission cathode

International Nuclear Information System (INIS)

Dovbnya, A.N.; Reshetnyak, N.G.; Zakutin, V.V.; Chertishchev, I.A.; Romas'ko, V.P.; Dovbnyan, N.A.

2013-01-01

Data are reported on electron beam generation and beam current control in two types of secondary-emission cathode magnetron guns. The influence of the magnetic field value and field distribution on the formation of the beam and its parameters has been investigated in the electron energy range between 20 and 150 keV. The influence of local magnetic field variations on the cathode and the electron beam characteristics has been studied. The possibility to control the electron beam current in various ways has been demonstrated

Angular dependence of the nanoDot OSL dosimeter

International Nuclear Information System (INIS)

Kerns, James R.; Kry, Stephen F.; Sahoo, Narayan; Followill, David S.; Ibbott, Geoffrey S.

2011-01-01

Purpose: Optically stimulated luminescent detectors (OSLDs) are quickly gaining popularity as passive dosimeters, with applications in medicine for linac output calibration verification, brachytherapy source verification, treatment plan quality assurance, and clinical dose measurements. With such wide applications, these dosimeters must be characterized for numerous factors affecting their response. The most abundant commercial OSLD is the InLight/OSL system from Landauer, Inc. The purpose of this study was to examine the angular dependence of the nanoDot dosimeter, which is part of the InLight system. Methods: Relative dosimeter response data were taken at several angles in 6 and 18 MV photon beams, as well as a clinical proton beam. These measurements were done within a phantom at a depth beyond the build-up region. To verify the observed angular dependence, additional measurements were conducted as well as Monte Carlo simulations in MCNPX. Results: When irradiated with the incident photon beams parallel to the plane of the dosimeter, the nanoDot response was 4% lower at 6 MV and 3% lower at 18 MV than the response when irradiated with the incident beam normal to the plane of the dosimeter. Monte Carlo simulations at 6 MV showed similar results to the experimental values. Examination of the results in Monte Carlo suggests the cause as partial volume irradiation. In a clinical proton beam, no angular dependence was found. Conclusions: A nontrivial angular response of this OSLD was observed in photon beams. This factor may need to be accounted for when evaluating doses from photon beams incident from a variety of directions.

Inhibitory action of certain cyclophosphate derivatives of cAMP on cAMP-dependent protein kinases

NARCIS (Netherlands)

Wit, René J.W. de; Hekstra, Doeke; Jastorff, Bernd; Stec, Wojciech J.; Baraniak, Janina; Driel, Roel van; Haastert, Peter J.M. van

1984-01-01

A series cAMP derivatives with modifications in the adenine, ribose and cyclophosphate moiety were screened for their binding affinity for the two types of cAMP-binding sites in mammalian protein kinase type I. In addition, the activation of the kinase by these analogs was monitored. The binding

From Nano Structure to Systems: Fabrication and Characterization

International Nuclear Information System (INIS)

Uda Hashim

2011-01-01

Currently, the interest in nano technology research has been grown rapidly. With the latest technology, it is possible to arrange atoms into structures that are only a few nanometers in size. Dimension for nano structure is between 0.1 and 100nm where the actual size of 1nm is equal to 10-9 m or just about a few atoms thick. In other word, a nano structure is an object which it size is about four atom diameters or 1/50000 of a human hair. Due to the connecting of a patterned silicon substrate with biomolecules and the small size and large surface-to-volume ratio, it opens much new possibility for assembling nano structures.The ultimate goal is to fabricate devices that have every atom in the right place. Such technology would give the opportunity to minimize the size of a device and to reduce the material, energy and time necessary to perform its task. Potential applications include electrical circuits, mechanical devices and medical instruments. There are two most important nano structures that are extensively studied and researched in various organizations which are nano wire and nano gap. Nano wires is a new class of nano structure that have attracted attention and great research interest in the last few years because of their potential applications in nano technology such as nano electronic, nano mechanical and biomedical engineering. Fabrication of Nano wires is one of the great challenges today. Conventional lithography methods are not capable to produce Nano wires and even with advance nano lithography sizes below 100 nm may not easily be achieved. Nano wire can be produced in two approaches, which are top down and bottom-up method. Very small nano wires which can be produced by using top-down nano fabrication methods are Scanning Electron Microscope (SEM) based Electron Beam Lithography (EBL) method, and Spacer Patterning Lithography (SPL) method. The top-down nano fabrication method based on EBL was the design of the Nano wires Pattern Design (NPD). The

Cancellation of OpAmp virtual ground imperfections by a negative conductance applied to improve RF receiver linearity

NARCIS (Netherlands)

Mahrof, D.H.; Klumperink, Eric A.M.; Ru, Z.; Oude Alink, M.S.; Nauta, Bram

2014-01-01

High linearity CMOS radio receivers often exploit linear V-I conversion at RF, followed by passive down-mixing and an OpAmp-based Transimpedance Amplifier at baseband. Due to nonlinearity and finite gain in the OpAmp, virtual ground is imperfect, inducing distortion currents. This paper proposes a

A Fabrication Technique for Nano-gap Electrodes by Atomic Force Microscopy Nano lithography

International Nuclear Information System (INIS)

Jalal Rouhi; Shahrom Mahmud; Hutagalung, S.D.; Kakooei, S.

2011-01-01

A simple technique is introduced for fabrication of nano-gap electrodes by using nano-oxidation atomic force microscopy (AFM) lithography with a Cr/ Pt coated silicon tip. AFM local anodic oxidation was performed on silicon-on-insulator (SOI) surfaces by optimization of desired conditions to control process in contact mode. Silicon electrodes with gaps of sub 31 nm were fabricated by nano-oxidation method. This technique which is simple, controllable, inexpensive and fast is capable of fabricating nano-gap structures. The current-voltage measurements (I-V) of the electrodes demonstrated very good insulating characteristics. The results show that silicon electrodes have a great potential for fabrication of single molecule transistors (SMT), single electron transistors (SET) and the other nano electronic devices. (author)

Proceedings of the 1979 workshop on beam current limitations in storage rings, July 16-27, 1979

International Nuclear Information System (INIS)

Pellegrini, C.

1979-01-01

The Workshop on Beam Current Limitations in Storage Rings was held at Brookhaven National Laboratory from July 16 to 27, 1979. The purpose of this Workshop was to discuss the physical mechanisms limiting the beam current or current density in accelerators or storage rings. Many of these machines are now being built or planned for a variety of applications, such as colliding beam experiments, synchrotron light production, heavy ion beams. This diversity was reflected in the Workshop and in the papers which have been contributed to these Proceedings. The twenty-one papers from the workshop were incorporated individually in the data base

Development of movable mask system to cope with high beam current

International Nuclear Information System (INIS)

Suetsugu, Y.; Shibata, K.; Sanami, T.; Kageyama, T.; Takeuchi, Y.

2003-01-01

The KEK B factory (KEKB), a high current electron-positron collider, has a movable mask (or collimator) system to reduce the background noise in the BELLE detector coming from spent particles. The early movable masks, however, had severe problems of heating, arcing, and vacuum leaks over the stored beam current of several hundred mA. The cause is intense trapped higher order modes (HOMs) excited at the mask head, where the cross section of the beam chamber changed drastically. The mask head, made of copper-tungsten alloy or pure copper, was frequently damaged by hitting of the high energy beam at the same time. Since the problems of the mask were revealed, several kinds of improved masks have been designed employing rf technologies in dealing with the HOM and installed to the ring step by step. Much progress has come from adopting a trapped-mode free structure, where the mask was a bent chamber itself. Recently the further improved mask with a reduced HOM design or HOM dampers was developed to suppress the heating of vacuum components near the mask due to the HOM traveling from the mask. To avoid damage to the mask head, on the other hand, a titanium mask head was tried. The latest masks are working as expected now at the stored beam current of 1.5 A. Presented are the problems and experiences on the movable mask system for the KEKB, which are characteristic of and common in a high intensity accelerator

Improvement of bunch-by-bunch beam current detection system in Hefei light source

International Nuclear Information System (INIS)

Zheng Kai; Wang Junhua; Liu Zuping; Li Weimin; Zhou Zeran; Yang Yongliang; Huang Longjun; Chen Yuanbo

2006-01-01

Bunch-by-bunch beam current detection system is an important facility in the multibunch storage ring. In this paper, the established bunch-by-bunch beam current detection systems for the accelerator such as Cornell, SLAC and KEKB were compared and studied. The design of the bunch-by-bunch beam current detection system for HLS, which was based on the bunch-by-bunch tracing measurement system in HLS was given. Both demodulation by sine wave and square were applied in this paper, the deviation of the detect system was determined by the longitudinal oscillation. Compared the data acquired from ADC with the data from DCCT, the ADC data was scaled by the bunch current. The standard deviations of linear fit were about 1%, and the standard deviations of polynomial fit were less than 0.5% in both sine wave and square wave demodulation. Some analysis of the measurement results also had been shown in this paper. (authors)

Current status and future prospect of electron beam sterilization in Japan

International Nuclear Information System (INIS)

Katsura, Ichiro

1998-01-01

It seems that electron beam sterilization is being current topic among all applications in Japan and that this tendency will continue until when major companies interested in the technology complete introducing electron beam. Since the Ministry of Health and Welfare(MOHW) officially issued revised regulation on GMP for medical devices in 1995, EtO has become the method regarded as time and money consuming one. On the contrary, electron beam has become as relatively economical and desirable method to achieve same result by its characteristics such as high productivity, rather easy validation and consequent cost reduction, although less penetration limit the kind of products to be treated. Status and prospect of electron beam sterilization in Japan will be presented in the paper along with accelerator related technologies

Nano-imprint gold grating as refractive index sensor

International Nuclear Information System (INIS)

Kumari, Sudha; Mohapatra, Saswat; Moirangthem, Rakesh S.

2016-01-01

Large scale of fabrication of plasmonic nanostructures has been a challenging task due to time consuming process and requirement of expensive nanofabrication tools such as electron beam lithography system, focused ion beam system, and extreme UV photolithography system. Here, we present a cost-effective fabrication technique so called soft nanoimprinting to fabricate nanostructures on the larger sample area. In our fabrication process, a commercially available optical DVD disc was used as a template which was imprinted on a polymer glass substrate to prepare 1D polymer nano-grating. A homemade nanoimprinting setup was used in this fabrication process. Further, a label-free refractive index sensor was developed by utilizing the properties of surface plasmon resonance (SPR) of a gold coated 1D polymer nano-grating. Refractive index sensing was tested by exposing different solutions of glycerol-water mixture on the surface of gold nano-grating. The calculated bulk refractive index sensitivity was found to be 751nm/RIU. We believed that our proposed SPR sensor could be a promising candidate for developing low-cost refractive index sensor with high sensitivity on a large scale.

Semiconductor Nano wires and Nano tubes: From Fundamentals to Diverse Applications

International Nuclear Information System (INIS)

Xiong, Q.; Grimes, C.A.; Zacharias, M.; Morral, A.F.; Hiruma, K.; Shen, G.

2012-01-01

Research in the field of semiconductor nano wires (SNWs) and nano tubes has been progressing into a mature subject with several highly interdisciplinary sub areas such as nano electronics, nano photonics, nano composites, bio sensing, optoelectronics, and solar cells. SNWs represent a unique system with novel properties associated to their one-dimensional (1D) structures. The fundamental physics concerning the formation of discrete 1D subbands, coulomb blockade effects, ballistic transport, and many-body phenomena in 1D nano wires and nano tubes provide a strong platform to explore the various scientific aspects in these nano structures. A rich variety of preparation methods have already been developed for generating well-controlled 1D nano structures and from a broad range of materials. The present special issue focuses on the recent development in the mechanistic understanding of the synthesis, the studies on electrical/optical properties of nano wires and their applications in nano electronics, nano photonics, and solar-energy harvesting. In this special issue, we have several invited review articles and contributed papers that are addressing current status of the fundamental issues related to synthesis and the diverse applications of semiconducting nano wires and nano tubes. One of the papers reviews the progress of the top-down approach of developing silicon-based vertically aligned nano wires to explore novel device architectures and integration schemes for nano electronics and clean energy applications. Another paper reviews the recent developments and experimental evidences of probing the confined optical and acoustic phonon in nonpolar semiconducting (Si and Ge) nano wires using Raman spectroscopy. The paper by K. Hiruma et al. spotlights the III semiconductor nano wires and demonstrates selective-area metal organic vapor phase epitaxy grown GaAs/In(Al)GaAs and InP/InAs/InP nano wires with heterojunctions along their axial and radial directions. The paper

The Nano-X Linear Accelerator: A Compact and Economical Cancer Radiotherapy System Incorporating Patient Rotation.

Science.gov (United States)

Eslick, Enid M; Keall, Paul J

2015-10-01

Rapid technological improvements in radiotherapy delivery results in improved outcomes to patients, yet current commercial systems with these technologies on board are costly. The aim of this study was to develop a state-of-the-art cancer radiotherapy system that is economical and space efficient fitting with current world demands. The Nano-X system is a compact design that is light weight combining a patient rotation system with a vertical 6 MV fixed beam. In this paper, we present the Nano-X system design configuration, an estimate of the system dimensions and its potential impact on shielding cost reductions. We provide an assessment of implementing such a radiotherapy system clinically, its advantages and disadvantages compared to a compact conventional gantry rotating linac. The Nano-X system has several differentiating features from current radiotherapy systems, it is [1] compact and therefore can fit into small vaults, [2] light weight, and [3] engineering efficient, i.e., it rotates a relatively light component and the main treatment delivery components are not under rotation (e.g., DMLCs). All these features can have an impact on reducing the costs of the system. In terms of shielding requirements, leakage radiation was found to be the dominant contributor to the Nano-X vault and as such no primary shielding was necessary. For a low leakage design, the Nano-X vault footprint and concrete volume required is 17 m2 and 35 m3 respectively, compared to 54 m2 and 102 m3 for a conventional compact linac vault, resulting in decreased costs in shielding. Key issues to be investigated in future work are the possible patient comfort concerns associated with the patient rotation system, as well as the magnitude of deformation and subsequent adaptation requirements. © The Author(s) 2014.

Electrodeposition of nickel nano wire arrays

International Nuclear Information System (INIS)

Nur Ubaidah Saidin; Kok Kuan Ying; Ng Inn Khuan; Nurazila Mat Zali; Siti Salwa Zainal Abidin

2010-01-01

Synthesis, characterization and assembly of one-dimensional nickel nano wires prepared by template directed electrodeposition are discussed in this paper. Parallel arrays of high aspect ratio nickel nano wires were electrodeposited using electrolytes with different cations and pH. The nano wires were characterized using X-ray diffractometry and scanning electron microscopy. It was found that the orientations of the electro deposited Ni nano wires were governed by the deposition current and the electrolyte conditions. Free standing nickel nano wires can be obtained by dissolving the template. Due to the magnetic nature of the nano wires, magnetic alignment was employed to assemble and position the free standing nano wires in the device structure. (author)

Nano catalysis: Academic Discipline and Industrial Realities

International Nuclear Information System (INIS)

Olveira, S.; Forster, S.P.; Seeger, S.

2014-01-01

Nano technology plays a central role in both academic research and industrial applications. Nano enabled products are not only found in consumer markets, but also importantly in business to business markets (B2B). One of the oldest application areas of nano technology is nano catalysis—an excellent example for such a B2 B market. Several existing reviews illustrate the scientific developments in the field of nano catalysis. The goal of the present review is to provide an up-to-date picture of academic research and to extend this picture by an industrial and economic perspective. We therefore conducted an extensive search on several scientific databases and we further analyzed more than 1,500 nano catalysis-related patents and numerous market studies. We found that scientists today are able to prepare nano catalysts with superior characteristics regarding activity, selectivity, durability, and recoverability, which will contribute to solve current environmental, social, and industrial problems. In industry, the potential of nano catalysis is recognized, clearly reflected by the increasing number of nano catalysis-related patents and products on the market. The current nano catalysis research in academic and industrial laboratories will therefore enable a wealth of future applications in the industry

Research and development of advanced materials using ion beam

Energy Technology Data Exchange (ETDEWEB)

Namba, Susumu [Nagasaki Inst. of Applied Science, Nagasaki (Japan)

1997-03-01

A wide range of research and development activities of advanced material synthesis using ion beams will be discussed, including ion beam applications to the state-of-the-art electronics from giant to nano electronics. (author)

Nanoscale insights into ion-beam cancer therapy

CERN Document Server

2017-01-01

This book provides a unique and comprehensive overview of state-of-the-art understanding of the molecular and nano-scale processes that play significant roles in ion-beam cancer therapy. It covers experimental design and methodology, and reviews the theoretical understanding of the processes involved. It offers the reader an opportunity to learn from a coherent approach about the physics, chemistry and biology relevant to ion-beam cancer therapy, a growing field of important medical application worldwide. The book describes phenomena occurring on different time and energy scales relevant to the radiation damage of biological targets and ion-beam cancer therapy from the molecular (nano) scale up to the macroscopic level. It illustrates how ion-beam therapy offers the possibility of excellent dose localization for treatment of malignant tumours, minimizing radiation damage in normal tissue whilst maximizing cell-killing within the tumour, offering a significant development in cancer therapy. The full potential ...

Cyclic AMP Inhibits the Activity and Promotes the Acetylation of Acetyl-CoA Synthetase through Competitive Binding to the ATP/AMP Pocket.

Science.gov (United States)

Han, Xiaobiao; Shen, Liqiang; Wang, Qijun; Cen, Xufeng; Wang, Jin; Wu, Meng; Li, Peng; Zhao, Wei; Zhang, Yu; Zhao, Guoping

2017-01-27

The high-affinity biosynthetic pathway for converting acetate to acetyl-coenzyme A (acetyl-CoA) is catalyzed by the central metabolic enzyme acetyl-coenzyme A synthetase (Acs), which is finely regulated both at the transcriptional level via cyclic AMP (cAMP)-driven trans-activation and at the post-translational level via acetylation inhibition. In this study, we discovered that cAMP directly binds to Salmonella enterica Acs (SeAcs) and inhibits its activity in a substrate-competitive manner. In addition, cAMP binding increases SeAcs acetylation by simultaneously promoting Pat-dependent acetylation and inhibiting CobB-dependent deacetylation, resulting in enhanced SeAcs inhibition. A crystal structure study and site-directed mutagenesis analyses confirmed that cAMP binds to the ATP/AMP pocket of SeAcs, and restrains SeAcs in an open conformation. The cAMP contact residues are well conserved from prokaryotes to eukaryotes, suggesting a general regulatory mechanism of cAMP on Acs. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Inorganic-organic hybrid polymer for preparation of affiliating material using electron beam irradiation

International Nuclear Information System (INIS)

Chung, Jaeseung; Kim, Seongeun; Kim, Byounggak; Lee, Jongchan; Park, Jihyun; Lee, Byeongcheol

2011-01-01

Recently, silver nano materials have gained a lot of attentions in a variety of applications due to the unique biological, optical, and electrical properties. Especially, the antifouling property of these material is considered to be an important character for biomedical field, marine coatings industry, biosensor, and drug delivery. In this study, we design and synthesize the inorganic-organic hybrid polymer for preparation of affiliating materials. Silver nano materials having antifouling property with different shapes are prepared by control the electron beam irradiation conditions. Inorganic-organic hybrid polymer was synthesized and characterized. → Morphology and size controlled nano materials are prepared using electron beam irradiation. → Silver nano materials having various shapes can be used for antifouling material

SU-F-T-554: Dark Current Effect On CyberKnife Beam Dosimetry

Energy Technology Data Exchange (ETDEWEB)

Kim, H; Chang, A [Soonchunhyang University Hospital, Seoul (Korea, Republic of)

2016-06-15

Purpose: All RF linear accelerators produce dark current to varying degrees when an accelerating voltage and RF input is applied in the absence of electron gun injection. This study is to evaluate how dark current from the linear accelerator of CyberKnife affect the dose in the reference dosimetry. Methods: The G4 CyberKnife system with 6MV photon beam was used in this study. Using the ion chamber and the diode detector, the dose was measured in water with varying time delay between acquiring charges and staring beam-on after applying high-voltage into the linear accelerator. The dose was measured after the time delay with over the range of 0 to 120 seconds in the accelerating high-voltage mode without beam-on, applying 0, 10, 50, 100, and 200 MUs. For the measurements, the collimator of 60 mm was used and the detectors were placed at the depths of 10 cm with the source-to-surface distance of 80 cm. Results: The dark current was constant over time regardless of MU. The dose due to the dark current increased over time linearly with the R-squared value of 0.9983 up to 4.4 cGy for the time 120 seconds. In the dose rate setting of 720 MU/min, the relative dose when applying the accelerating voltage without beam-on was increased over time up to 0.6% but it was less than the leakage radiation resulted from the accelerated head. As the reference dosimetry condition, when 100 MU was delivered after 10 seconds time delay, the relative dose increased by 0.7% but 6.7% for the low MU (10 MU). Conclusion: In the dosimetry using CyberKnife system, the constant dark current affected to the dose. Although the time delay in the accelerating high-voltage mode without beam-on is within 10 seconds, the dose less than 100 cGy can be overestimated more than 1%.

The measurement of stress and phase fraction distributions in pre and post-transition Zircaloy oxides using nano-beam synchrotron X-ray diffraction

Energy Technology Data Exchange (ETDEWEB)

Swan, H., E-mail: helen.swan@nnl.co.uk [National Nuclear Laboratory, Building D5, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB (United Kingdom); Blackmur, M.S., E-mail: matthew.s.blackmur@nnl.co.uk [National Nuclear Laboratory, Building D5, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB (United Kingdom); Hyde, J.M., E-mail: jonathan.m.hyde@nnl.co.uk [National Nuclear Laboratory, Building D5, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB (United Kingdom); Laferrere, A., E-mail: alice.laferrere@atkinsglobal.com [W.S.Atkins, The Hub, Aztec West, 500 Park Ave, Almondsbury, Bristol BS32 4RZ (United Kingdom); Ortner, S.R., E-mail: susan.r.ortner@nnl.co.uk [National Nuclear Laboratory, Building D5, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB (United Kingdom); Styman, P.D., E-mail: paul.d.styman@nnl.co.uk [National Nuclear Laboratory, Building D5, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB (United Kingdom); Staines, C., E-mail: cassie.staines@nnl.co.uk [National Nuclear Laboratory, 102B, Stonehouse Park, Stonehouse, Gloucestershire, GL10 3UT (United Kingdom); Gass, M., E-mail: mhairi.gass@amecfw.com [Amec Foster Wheeler Clean Energy Europe, Walton House, Birchwood, WA3 6GA (United Kingdom); Hulme, H., E-mail: helen.hulme@amecfw.com [Amec Foster Wheeler Clean Energy Europe, Walton House, Birchwood, WA3 6GA (United Kingdom); Cole-Baker, A., E-mail: aidan.cole-baker@rolls-royce.com [Rolls-Royce plc, PO Box 2000, Derby, DE21 7XX (United Kingdom); Frankel, P., E-mail: philipp.frankel@manchester.ac.uk [Materials Performance Centre, School of Materials, The University of Manchester, Manchester, M13 9PL (United Kingdom)

2016-10-15

Zircaloy-4 oxide stress profiles and tetragonal:monoclinic oxide phase fraction distributions were studied using nano-beam transmission X-ray diffraction. Continuous stress relief and phase transformation during the first cycle of oxide growth was observed. The in-plane monoclinic stress was shown to relax strongly up to each transition, whereas in-plane tetragonal stress-relief (near the metal-oxide interface) was only observed post transition. The research demonstrates that plasticity in the metal and the development of a band of in-plane cracking both relax the monoclinic in-plane stress. The observations are consistent with a model of transition in which in-plane cracking becomes interlinked prior to transition. These cracks, combined with the development of cracks with a through-thickness component (driven primarily by plasticity in the metal) and/or a porous network of fine cracks (associated with phase transformation), form a percolation path through the oxide layer. The oxidising species can then percolate from the oxide surface to the metal/oxide interface, at which stage transition then ensues. - Highlights: • Measurement of stress in Zr-4 oxides using nano-beam transmission X-ray diffraction. • In-plane monoclinic stress relaxes strongly up to each transition. • In-plane tetragonal stress relaxation is only observed post transition. • Development of band of cracking is related to monoclinic in-plane stress relaxation. • Linking of in-plane cracking with through-plane crack/porosity leads to transition.

Beam current monitoring in the AGS Booster and its transfer lines

International Nuclear Information System (INIS)

Witkover, R.L.; Zitvogel, E.; Castillo, V.

1991-01-01

The new AGS Booster is designed to accelerate low intensity polarized protons and heavy ions, and high intensity protons. The wide range of beam parameters and the vacuum, thermal and radiation environment, presented challenges in the instrumentation design. This paper describes the problems and solutions for the beam current monitors in the Booster and its transport lines. Where available, results of the initial operation will be presented. 11 refs., 3 figs

Numerical simulation of the processes of small-diameter high-current electron beam shaping and injection

CERN Document Server

Gordeev, V S; Myskov, G A

2001-01-01

With the aid of BEAM 25 program there was carried out the numerical simulation of the non-stationary process of shaping a small-diameter (<= 20mm) high-current hollow electron beam in a diode with magnetic insulation,as well as of the process of beam injection into the accelerating LIA track. The diode configuration for the purpose of eliminating the leakage of electron flux to the anode surface was update. Presented are the results of calculation of the injected beam characteristics (amplitude-time parameters of a current pulse, space-angle distributions of electrons etc.) depending on diode geometric parameters.

Study on the nanostructure formation mechanism of hypereutectic Al–17.5Si alloy induced by high current pulsed electron beam

Energy Technology Data Exchange (ETDEWEB)

Gao, Bo, E-mail: gaob@smm.neu.edu.cn [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Hu, Liang [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Li, Shi-wei [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Hao, Yi [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Zhang, Yu-dong [Laboratoire d’Etude des Textures et Applications aux Matériaux (LETAM, UMR-CNRS 7078), Université Paul Verlaine de Metz, Ile du Saulcy, Metz 57012 (France); Tu, Gan-feng [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Grosdidier, Thierry [Laboratoire d’Etude des Textures et Applications aux Matériaux (LETAM, UMR-CNRS 7078), Université Paul Verlaine de Metz, Ile du Saulcy, Metz 57012 (France)

2015-08-15

This work investigates the nanostructure forming mechanism of hypereutectic Al–17.5Si alloy associated with the high current pulsed electron beam (HCPEB) treatment with increasing number of pulses by electron backscatter diffraction (EBSD) and SEM. The surface layers were melted and resolidified rapidly. The treated surfaces show different structural characteristics in different compositions and distribution zones. The top melted-layer zone can be divided into three zones: Si-rich, Ai-rich, and intermediate zone. The Al-rich zone has a nano-cellular microstructure with a diameter of ∼100 nm. The microstructure in the Si-rich zone consists of fine, dispersive, and spherical nano-sized Si crystals surrounded by α(Al) cells. Some superfine eutectic structures form in the boundary of the two zones. With the increase of number of pulses, the proportion of Si-rich zone to the whole top surface increases, and more cellular substructures are transformed to fine equiaxed grain. In other words, with increasing number of pulses, more Si elements diffuse to the Al-rich zone and provide heterogeneous nucleation sites, and Al grains are refined dramatically. Moreover, the relationship between the substrate Si phase and crystalline phase is determined by EBSD; that is, (1 1 1){sub Al}//(0 0 1){sub Si} with a value of disregistry δ at approximately 5%. The HCPEB technique is a versatile technique for refining the surface microstructure of hypereutectic Al–Si alloys.

Combined addition of nano diamond and nano SiO{sub 2}, an effective method to improve the in-field critical current density of MgB{sub 2} superconductor

Energy Technology Data Exchange (ETDEWEB)

Rahul, S.; Varghese, Neson; Vinod, K.; Devadas, K.M.; Thomas, Syju; Anees, P. [National Institute for Interdisciplinary Science and Technology (CSIR), Trivandrum 695019 (India); Chattopadhyay, M.K.; Roy, S.B. [Magnetic and Superconducting Materials Section, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Syamaprasad, U., E-mail: syamcsir@gmail.com [National Institute for Interdisciplinary Science and Technology (CSIR), Trivandrum 695019 (India)

2011-11-15

Highlights: {yields} Both nano diamond and nano SiO{sub 2} caused significant modifications in the structural properties of pure MgB{sub 2} sample. {yields} Reduction in T{sub C} for the best codoped sample was approximately 2 K. {yields} The best codoped sample yielded a J{sub C}, an order of magnitude more than the undoped one at 5 K and 8 T. {yields} The enhanced flux pinning capability provided by the additives is responsible for the improved in-field J{sub C}. -- Abstract: MgB{sub 2} bulk samples added with nano SiO{sub 2} and/or nano diamond were prepared by powder-in-sealed-tube (PIST) method and the effects of addition on structural and superconducting properties were studied. X-ray diffraction (XRD) analysis revealed that the addition caused systematic reduction in 'a' lattice parameter due to the substitution of C atoms at B sites and the strain caused by reacted intragrain nano particles of Mg{sub 2}Si as evinced by transmission electron microscope image. Scanning electron microscopy images showed distinct microstructural variations with SiO{sub 2}/diamond addition. It was evident from DC magnetization measurements that the in-field critical current density [J{sub C}(H)] of doped samples did not fall drastically like the undoped sample. Among the doped samples the J{sub C}(H) of co-doped samples were significantly higher and the best co-doped sample yielded a J{sub C}, an order of magnitude more than the undoped one at 5 K and 8 T.

Two-stream Stability Properties of the Return-Current Layer for Intense Ion Beam Propagation Through Background Plasma

International Nuclear Information System (INIS)

Startsev, Edward A.; Davidson, Ronald C.; Dorf, Mikhail

2009-01-01

When an ion beam with sharp edge propagates through a background plasma, its current is neutralized by the plasma return current everywhere except at the beam edge over a characteristic transverse distance Δx perpendicular ∼ (delta) pe , where (delta) pe = c/ω pe is the collisionless skin depth, and ω pe is the electron plasma frequency. Because the background plasma electrons neutralizing the ion beam current inside the beam are streaming relative to the background plasma electrons outside the beam, the background plasma can support a two-stream surface-mode excitation. Such surface modes have been studied previously assuming complete charge and current neutralization, and have been shown to be strongly unstable. In this paper we study the detailed stability properties of this two-stream surface mode for an electron flow velocity profile self-consistently driven by the ion beam. In particular, it is shown that the self-magnetic field generated inside the unneutralized current layer, which has not been taken into account previously, completely eliminates the instability

Beam instability during high-current heavy-ion beam transport

International Nuclear Information System (INIS)

Kikuchi, T.; Someya, T.; Kawata, S.; Nakajima, M.; Horioka, K.

2005-01-01

In driver system for heavy ion inertial fusion, beam dynamics is investigated by particle-in-cell simulations during final beam bunching. The particle simulations predict that the beam is transported with the localized transverse charge distribution induced by the strong space charge effect. The calculation results also show that the emittance growth during the longitudinal bunch compression for various particle distributions at the initial conditions and with two types of transverse focusing model, which are a continuous focusing and an alternating gradient focusing lattice configurations. (author)

A Four Channel Beam Current Monitor Data Acquisition System Using Embedded Processors

Energy Technology Data Exchange (ETDEWEB)

Wheat, Jr., Robert Mitchell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dalmas, Dale A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dale, Gregory E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-08-11

Data acquisition from multiple beam current monitors is required for electron accelerator production of Mo-99. A two channel system capable of recording data from two beam current monitors has been developed, is currently in use, and is discussed below. The development of a cost-effective method of extending this system to more than two channels and integrating of these measurements into an accelerator control system is the main focus of this report. Data from these current monitors is digitized, processed, and stored by a digital data acquisition system. Limitations and drawbacks with the currently deployed digital data acquisition system have been identified as have been potential solutions, or at least improvements, to these problems. This report will discuss and document the efforts we've made in improving the flexibility and lowering the cost of the data acquisition system while maintaining the minimum requirements.

Nano market and analysis of technology

International Nuclear Information System (INIS)

2001-10-01

This book gives descriptions of summary of nano technology with meaning, character and field, trend of technical development in domestic, current condition of nano basic research in domestic, trend of technical development in foreign country such as summary, trend of technology by industrial field, machine and metronics, material and process, standard of nano mechanism, scale of market and trend, competitiveness of nano technology of major country and research development system in Japan, Korean company and major countries.

Regulation of melanogenesis: the role of cAMP and MITF

Directory of Open Access Journals (Sweden)

Michał Otręba

2012-01-01

Full Text Available The article presents the melanogenesis pathway and the role of cyclic adenosine monophosphate (cAMP and microphthalmia transcription factor (MITF in regulation of this process. Products of melanogenesis are eu- and/or pheomelanins synthesized in a multistage process of tyrosine oxidation and polymerization. The conversions require the presence of tyrosinase (TYR, key enzyme, tyrosine hydroxylase isoform I (THI and tyrosinase related proteins (TRP1 and TRP2. Many types of signal molecules and transcription factors participate in regulation of melanin synthesis, but the most important are cAMP and MITF. cAMP is the second messenger in the intracellular signal cascade, which is synthesized from adenosine triphosphate (ATP by adenylyl cyclase, activated among others by the melanocortin receptor and the αS subunit of G protein. The signal molecule cAMP regulates MITF, TYR, THI, GTP-cyclohydroxylase I (GTP-CHI transcription and phenylalanine hydroxylase (PAH phosphorylation at Ser16 by protein kinase A (PKA. Mutations of genes encoding proteins belonging to the cAMP signal cascade may lead to McCune-Albright and Carney syndromes. MITF is one of the most important nuclear transcription factors regulating melanogenesis. Currently 10 isoforms of human MITF are known, but in melanocytes only MITF-M, MITF-Mdel, MITF-A and MITF-H occur. MITF transcription factor regulates melanogenesis by activation of tyrosinase, TRP1 and TRP2 transcription. It also affects expression of other factors regulating melanosome maturation, biogenesis and transport. Moreover, it regulates melanocyte proliferation and protection against apoptosis. Mutations of the MITF gene may lead to hereditary diseases: Waardenburg type II and Tietz syndromes.

A nano-graphite cold cathode for an energy-efficient cathodoluminescent light source

Directory of Open Access Journals (Sweden)

Alexander N. Obraztsov

2013-08-01

Full Text Available The development of new types of light sources is necessary in order to meet the growing demands of consumers and to ensure an efficient use of energy. The cathodoluminescence process is still under-exploited for light generation because of the lack of cathodes suitable for the energy-efficient production of electron beams and appropriate phosphor materials. In this paper we propose a nano-graphite film material as a highly efficient cold cathode, which is able to produce high intensity electron beams without energy consumption. The nano-graphite film material was produced by using chemical vapor deposition techniques. Prototypes of cathodoluminescent lamp devices with a construction optimized for the usage of nano-graphite cold cathodes were developed, manufactured and tested. The results indicate prospective advantages of this type of lamp and the possibility to provide advanced power efficiency as well as enhanced spectral and other characteristics.

Bio-Nano ECRIS: An electron cyclotron resonance ion source for new materials production

Energy Technology Data Exchange (ETDEWEB)

Uchida, T. [Bio-Nano Electronics Research Centre, Toyo University, 2100, Kujirai, Kawagoe, Saitama 350-8585 (Japan); Minezaki, H. [Graduate School of Engineering, Toyo University, 2100, Kujirai, Kawagoe, Saitama 350-8585 (Japan); Tanaka, K.; Asaji, T. [Tateyama Machine Co., Ltd., 30 Shimonoban, Toyama, Toyama 930-1305 (Japan); Muramatsu, M.; Kitagawa, A. [National Institute of Radiological Sciences (NIRS), 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Kato, Y. [Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Biri, S. [Institute of Nuclear Research (ATOMKI), H-4026 Debrecen, Bem Ter 18/c (Hungary); Yoshida, Y. [Bio-Nano Electronics Research Centre, Toyo University, 2100, Kujirai, Kawagoe, Saitama 350-8585 (Japan); Graduate School of Engineering, Toyo University, 2100, Kujirai, Kawagoe, Saitama 350-8585 (Japan)

2010-02-15

We developed an electron cyclotron resonance ion source (ECRIS) for new materials production on nanoscale. Our main target is the endohedral fullerenes, which have potential in medical care, biotechnology, and nanotechnology. In particular, iron-encapsulated fullerene can be applied as a contrast material for magnetic resonance imaging or microwave heat therapy. Thus, our new ECRIS is named the Bio-Nano ECRIS. In this article, the recent progress of the development of the Bio-Nano ECRIS is reported: (i) iron ion beam production using induction heating oven and (ii) optimization of singly charged C{sub 60} ion beam production.

The CytR repressor antagonizes cyclic AMP-cyclic AMP receptor protein activation of the deoCp2 promoter of Escherichia coli K-12

DEFF Research Database (Denmark)

Søgaard-Andersen, L; Martinussen, J; Møllegaard, N E

1990-01-01

We have investigated the regulation of the Escherichia coli deoCp2 promoter by the CytR repressor and the cyclic AMP (cAMP) receptor protein (CRP) complexed to cAMP. Promoter regions controlled by these two proteins characteristically contain tandem cAMP-CRP binding sites. Here we show that (i) Cyt...

Superconducting nano-striplines as quantum detectors

International Nuclear Information System (INIS)

Casaburi, A.; Ejrnaes, M.; Mattioli, F.; Gaggero, A.; Leoni, R.; Martucciello, N.; Pagano, S.; Ohkubo, M.; Cristiano, R.

2011-01-01

The recent progress in the nanofabrication of superconducting films opens the road toward detectors with highly improved performances. This is the case for superconducting nano-striplines where the thickness and the width are pushed down to the extreme limits to realize detectors with unprecedented sensitivity and ultra fast response time. In this way quantum detectors for single photons at telecommunication wavelengths and for macromolecules such as proteins can be realized. As is often the case in applied nanotechnology, it is a challenge to make devices with the necessary macroscopic dimensions that are needed to interface present technologies, while maintaining the performance improvements. For nano-stripline detectors, both the fast temporal response and the device sensitivity is generally degraded when the area is increased. Here, we present how such detectors can be scaled up to macroscopic dimensions without losing the performance of the nano-structured active elements by using an innovative configuration. In order to realize ultrathin superconducting film the nano-layer is growth with a careful setup of the deposition technique which guarantees high quality and thickness uniformity at the nano-scale size. The active nano-strips are defined with the state-of-the-art electron beam nanolithography to achieve a highly uniform linewidth. We present working detectors based on nano-strips with thicknesses 9–40 nm and widths of 100–1000 nm which exhibit unprecedented speed and area coverage (40 × 40 μm 2 for single photon detectors and 1 × 1 mm 2 for single molecule detectors) based on niobium nitride thus enabling practical use of this nanotechnology.

Magnetic fields with photon beams: Use of circular current loops

International Nuclear Information System (INIS)

Jette, David

2001-01-01

Strong transverse magnetic fields can produce very large dose enhancements and reductions in localized regions of a patient under irradiation by a photon beam. Through EGS4 Monte Carlo simulations, we have examined the effects of applying a magnetic field produced by a pair of circular current loops to a photon beam penetrating a water phantom of finite thickness. We have indeed found very substantial localized dose enhancements, albeit with no corresponding dose reduction just distal to the region of dose enhancement. (However, dose reduction does occur near the distal end of the phantom.) We have also observed two phenomena to be concerned with, for this configuration: significant broadening of the penumbra close to the current loop, and narrowness of the enhanced dose region in a plane parallel to the planes of the loops. We have also examined the use of a single current loop to produce the magnetic field, and have found great asymmetry in the dose distribution; this asymmetry appears to make it impossible to treat with a single circular magnet a tumor of large dimension extending below the application surface

Decoding spatial and temporal features of neuronal cAMP/PKA signaling with FRET biosensors.

Science.gov (United States)

Castro, Liliana R V; Guiot, Elvire; Polito, Marina; Paupardin-Tritsch, Daniéle; Vincent, Pierre

2014-02-01

Cyclic adenosine monophosphate (cAMP) and the cyclic-AMP-dependent protein kinase (PKA) regulate a plethora of cellular functions in virtually all eukaryotic cells. In neurons, the cAMP/PKA signaling cascade controls a number of biological properties such as axonal growth, pathfinding, efficacy of synaptic transmission, regulation of excitability, or long term changes. Genetically encoded optical biosensors for cAMP or PKA are considerably improving our understanding of these processes by providing a real-time measurement in living neurons. In this review, we describe the recent progress made in the creation of biosensors for cAMP or PKA activity. These biosensors revealed profound differences in the amplitude of the cAMP signal evoked by neuromodulators between various neuronal preparations. These responses can be resolved at the level of individual neurons, also revealing differences related to the neuronal type. At the sub-cellular level, biosensors reported different signal dynamics in domains like dendrites, cell body, nucleus, and axon. Combining this imaging approach with pharmacology or genetic models points at phosphodiesterases and phosphatases as critical regulatory proteins. Biosensor imaging will certainly emerge as a forefront tool to decipher the subtle mechanics of intracellular signaling. This will certainly help us to understand the mechanism of action of current drugs and foster the development of novel molecules for neuropsychiatric diseases. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Raster-scanning serial protein crystallography using micro- and nano-focused synchrotron beams

Energy Technology Data Exchange (ETDEWEB)

Coquelle, Nicolas [Université Grenoble Alpes, IBS, 38044 Grenoble (France); CNRS, IBS, 38044 Grenoble (France); CEA, IBS, 38044 Grenoble (France); Brewster, Aaron S. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Kapp, Ulrike; Shilova, Anastasya; Weinhausen, Britta [European Synchrotron Radiation Facility, BP 220, 38043 Grenoble (France); Burghammer, Manfred, E-mail: burgham@esrf.fr [European Synchrotron Radiation Facility, BP 220, 38043 Grenoble (France); Ghent University, Ghent B-9000 (Belgium); Colletier, Jacques-Philippe, E-mail: burgham@esrf.fr [Université Grenoble Alpes, IBS, 38044 Grenoble (France); CNRS, IBS, 38044 Grenoble (France); CEA, IBS, 38044 Grenoble (France)

2015-05-01

A raster scanning serial protein crystallography approach is presented, that consumes as low ∼200–700 nl of sedimented crystals. New serial data pre-analysis software, NanoPeakCell, is introduced. High-resolution structural information was obtained from lysozyme microcrystals (20 µm in the largest dimension) using raster-scanning serial protein crystallography on micro- and nano-focused beamlines at the ESRF. Data were collected at room temperature (RT) from crystals sandwiched between two silicon nitride wafers, thereby preventing their drying, while limiting background scattering and sample consumption. In order to identify crystal hits, new multi-processing and GUI-driven Python-based pre-analysis software was developed, named NanoPeakCell, that was able to read data from a variety of crystallographic image formats. Further data processing was carried out using CrystFEL, and the resultant structures were refined to 1.7 Å resolution. The data demonstrate the feasibility of RT raster-scanning serial micro- and nano-protein crystallography at synchrotrons and validate it as an alternative approach for the collection of high-resolution structural data from micro-sized crystals. Advantages of the proposed approach are its thriftiness, its handling-free nature, the reduced amount of sample required, the adjustable hit rate, the high indexing rate and the minimization of background scattering.

Anisotropic stress in narrow sGe fin field-effect transistor channels measured using nano-focused Raman spectroscopy

Science.gov (United States)

Nuytten, T.; Bogdanowicz, J.; Witters, L.; Eneman, G.; Hantschel, T.; Schulze, A.; Favia, P.; Bender, H.; De Wolf, I.; Vandervorst, W.

2018-05-01

The continued importance of strain engineering in semiconductor technology demands fast and reliable stress metrology that is non-destructive and process line-compatible. Raman spectroscopy meets these requirements but the diffraction limit prevents its application in current and future technology nodes. We show that nano-focused Raman scattering overcomes these limitations and can be combined with oil-immersion to obtain quantitative anisotropic stress measurements. We demonstrate accurate stress characterization in strained Ge fin field-effect transistor channels without sample preparation or advanced microscopy. The detailed analysis of the enhanced Raman response from a periodic array of 20 nm-wide Ge fins provides direct access to the stress levels inside the nanoscale channel, and the results are validated using nano-beam diffraction measurements.

Editorial Emerging Multifunctional Nano structures

International Nuclear Information System (INIS)

Fan, H.; Lu, Y.; Ramanath, G.; Pomposo, J.A.

2009-01-01

The interest in emerging nano structures is growing exponentially since they are promising building blocks for advanced multifunctional nano composites. In recent years, an evolution from the controlled synthesis of individual monodisperse nanoparticles to the tailored preparation of hybrid spherical and also unsymmetrical multiparticle nano structures is clearly observed. As a matter of fact, the field of nano structures built around a nano species such as inside, outside, and next to a nanoparticle is becoming a new evolving area of research and development with potential applications in improved drug delivery systems, innovative magnetic devices, biosensors, and highly efficient catalysts, among several others Emerging nano structures with improved magnetic, conducting and smart characteristics are currently based on the design, synthesis, characterization and modeling of multifunctional nano object-based materials. In fact, core-shell nanoparticles and other related complex nano architectures covering a broad spectrum of materials (from metal and metal oxide to fused carbon, synthetic polymer, and bio polymer structures) to nano structure morphologies (spherical, cylindrical, star-like, etc.) are becoming the main building blocks for next generation of drug delivery systems, advanced sensors and biosensors, or improved nano composites. The five papers presented in this special issue examine the preparation and characterization of emerging multifunctional materials, covering from hybrid asymmetric structures to engineering nano composites.

Brightness measurement of an electron impact gas ion source for proton beam writing applications

Energy Technology Data Exchange (ETDEWEB)

Liu, N.; Santhana Raman, P. [Centre for Ion Beam Applications, Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583 (Singapore); Xu, X.; Pang, R.; Kan, J. A. van, E-mail: phyjavk@nus.edu.sg [Centre for Ion Beam Applications, Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Khursheed, A. [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583 (Singapore)

2016-02-15

We are developing a high brightness nano-aperture electron impact gas ion source, which can create ion beams from a miniature ionization chamber with relatively small virtual source sizes, typically around 100 nm. A prototype source of this kind was designed and successively micro-fabricated using integrated circuit technology. Experiments to measure source brightness were performed inside a field emission scanning electron microscope. The total output current was measured to be between 200 and 300 pA. The highest estimated reduced brightness was found to be comparable to the injecting focused electron beam reduced brightness. This translates into an ion reduced brightness that is significantly better than that of conventional radio frequency ion sources, currently used in single-ended MeV accelerators.

LAMPF experimental-area beam current monitors

International Nuclear Information System (INIS)

Tallerico, P.J.

1975-01-01

This paper summarizes the design and operational performance of a wide- range current monitor system used to measure charged-particle currents in the experimental areas of the Clinton P. Anderson Meson Physics Facility (LAMPF), a proton accelerator. The major features of the system are high sensitivity, wide dynamic range, and the ability to withstand high levels of radiation. The current pulses detected are from 50 μs to 1 ms in duration at repetition rates of from 1 to 120 Hz. The pulse amplitude varies from 1 μA to 17 mA of protons or H - ions. Both real-time and integrated outputs are available, and the minimum detectable currents are 1 μA at the video output and 50 nA at the integrated output. The basic system is comprised of toroids, preamplifiers, signal conditioners, voltage-to-frequency converters, and digital accumulators. The entire system is spread out over 1 km of beam pipe. Provision is made for calibration and for sending the outputs to remote users. The system is normally controlled by a small digital computer, which allows the system to be quite flexible in operation. The design features of the toroids and the associated electronics are discussed in detail, with emphasis on the steps taken to reduce noise and make the toroids temperature and radiation resistant

Free vibration analysis of a multiple rotating nano-beams system based on the Eringen nonlocal elasticity theory

Energy Technology Data Exchange (ETDEWEB)

Ghafarian, M.; Ariaei, A., E-mail: ariaei@eng.ui.ac.ir [Department of Mechanical Engineering, Faculty of Engineering, University of Isfahan, Isfahan (Iran, Islamic Republic of)

2016-08-07

The free vibration analysis of a multiple rotating nanobeams' system applying the nonlocal Eringen elasticity theory is presented. Multiple nanobeams' systems are of great importance in nano-optomechanical applications. At nanoscale, the nonlocal effects become non-negligible. According to the nonlocal Euler-Bernoulli beam theory, the governing partial differential equations are derived by incorporating the nonlocal scale effects. Assuming a structure of n parallel nanobeams, the vibration of the system is described by a coupled set of n partial differential equations. The method involves a change of variables to uncouple the equations and the differential transform method as an efficient mathematical technique to solve the nonlocal governing differential equations. Then a number of parametric studies are conducted to assess the effect of the nonlocal scaling parameter, rotational speed, boundary conditions, hub radius, and the stiffness coefficients of the elastic interlayer media on the vibration behavior of the coupled rotating multiple-carbon-nanotube-beam system. It is revealed that the bending vibration of the system is significantly influenced by the rotational speed, elastic mediums, and the nonlocal scaling parameters. This model is validated by comparing the results with those available in the literature. The natural frequencies are in a reasonably good agreement with the reported results.

Characterization techniques for the high-brightness particle beams of the Advanced Photon Source (APS)