Nuclear Reaction Data Centers

International Nuclear Information System (INIS)

McLane, V.; Nordborg, C.; Lemmel, H.D.; Manokhin, V.N.

1988-01-01

The cooperating Nuclear Reaction Data Centers are involved in the compilation and exchange of nuclear reaction data for incident neutrons, charged particles and photons. Individual centers may also have services in other areas, e.g., evaluated data, nuclear structure and decay data, reactor physics, nuclear safety; some of this information may also be exchanged between interested centers. 20 refs., 1 tab

Modification of quinone electrochemistry by the proteins in the biological electron transfer chains: examples from photosynthetic reaction centers

Science.gov (United States)

Gunner, M. R.; Madeo, Jennifer; Zhu, Zhenyu

2009-01-01

Quinones such as ubiquinone are the lipid soluble electron and proton carriers in the membranes of mitochondria, chloroplasts and oxygenic bacteria. Quinones undergo controlled redox reactions bound to specific sites in integral membrane proteins such as the cytochrome bc1 oxidoreductase. The quinone reactions in bacterial photosynthesis are amongst the best characterized, presenting a model to understand how proteins modulate cofactor chemistry. The free energy of ubiquinone redox reactions in aqueous solution and in the QA and QB sites of the bacterial photosynthetic reaction centers (RCs) are compared. In the primary QA site ubiquinone is reduced only to the anionic semiquinone (Q•−) while in the secondary QB site the product is the doubly reduced, doubly protonated quinol (QH2). The ways in which the protein modifies the relative energy of each reduced and protonated intermediate are described. For example, the protein stabilizes Q•− while destabilizing Q= relative to aqueous solution through electrostatic interactions. In addition, kinetic and thermodynamic mechanisms for stabilizing the intermediate semiquinones are compared. Evidence for the protein sequestering anionic compounds by slowing both on and off rates as well as by binding the anion more tightly is reviewed. PMID:18979192

Overall view of PLB and OMS / RCS engine thrusting

Science.gov (United States)

1983-01-01

Overall payload bay (PLB) view shows Inertial Upper Stage (IUS) Airborne Support Equipment (ASE) forward frame and aft frame tilt actuator (AFTA) table after IUS Tracking and Data Relay Satellite (TDRS) deploy. Vertical tail and Orbital Maneuvering System (OMS) pods with rear reaction control system (RCS) thruster firing (sidefiring) appears in background against blackness of space. Right right jet firing was photographed from more than 18 meters (60 feet) away in the cabin of the Earth-orbiting Challenger, Orbiter Vehicle (OV) 099.

Analysis of effect of late water injection on RCS repressurization

International Nuclear Information System (INIS)

Tao Jun; Cao Xuewu

2011-01-01

Effect of late water injection on RCS repressurization during high pressure severe accident sequence in a typical PWR was analyzed. As the results shown, late water injection could increase RCS pressure when RPV failed without RCS passive depressurization. Especially in the condition of opening one PORV, RCS pressure could reach high pressure limit when RPV failed and the risk of HPME and DCH was dramatically increased. Integrity of containment could be threatened. However, in the condition of RCS passive depressurization induced by pressurizer surge line creep failure, RCS pressure could be decreased to very low level even only one PORV was opened and two trains of emergency core cooling were implemented. The risk of HPME and DCH was eliminated. The more PORVs were opened, the faster accident progression was and the earlier RPV failed. RCS pressure was a little higher when PRV failed if two trains of emergency core cooling was implemented comparing with the condition with only one train of emergency core cooling. However the time of RPV failure was obviously delayed. From the point of delaying RPV failure and preventing containment early failure of view, the optimized late water injection was opening three PORVs and implementing two trains of emergency core cooling. (authors)

A Perspective on Reagent Diversity and Non-covalent Binding of Reactive Carbonyl Species (RCS and Effector Reagents in Non-enzymatic Glycation (NEG: Mechanistic Considerations and Implications for Future Research

Directory of Open Access Journals (Sweden)

Kenneth J. Rodnick

2017-06-01

Full Text Available This perspective focuses on illustrating the underappreciated connections between reactive carbonyl species (RCS, initial binding in the nonenzymatic glycation (NEG process, and nonenzymatic covalent protein modification (here termed NECPM. While glucose is the central species involved in NEG, recent studies indicate that the initially-bound glucose species in the NEG of human hemoglobin (HbA and human serum albumin (HSA are non-RCS ring-closed isomers. The ring-opened glucose, an RCS structure that reacts in the NEG process, is most likely generated from previously-bound ring-closed isomers undergoing concerted acid/base reactions while bound to protein. The generation of the glucose RCS can involve concomitantly-bound physiological species (e.g., inorganic phosphate, water, etc.; here termed effector reagents. Extant NEG schemes do not account for these recent findings. In addition, effector reagent reactions with glucose in the serum and erythrocyte cytosol can generate RCS (e.g., glyoxal, glyceraldehyde, etc.. Recent research has shown that these RCS covalently modify proteins in vivo via NECPM mechanisms. A general scheme that reflects both the reagent and mechanistic diversity that can lead to NEG and NECPM is presented here. A perspective that accounts for the relationships between RCS, NEG, and NECPM can facilitate the understanding of site selectivity, may help explain overall glycation rates, and may have implications for the clinical assessment/control of diabetes mellitus. In view of this perspective, concentrations of ribose, fructose, Pi, bicarbonate, counter ions, and the resulting RCS generated within intracellular and extracellular compartments may be of importance and of clinical relevance. Future research is also proposed.

Inferior ectopic pupil and typical ocular coloboma in RCS rats.

Science.gov (United States)

Tsuji, Naho; Ozaki, Kiyokazu; Narama, Isao; Matsuura, Tetsuro

2011-08-01

Ocular coloboma is sometimes accompanied by corectopia in humans and therefore ectopic pupil may indicate ocular coloboma in experimental animals. The RCS strain of rats has a low incidence of microphthalmia. We found that inferior ectopic pupil is associated exclusively with small-sized eyes in this strain. The objective of the current study was to evaluate whether inferior ectopic pupil is associated with iridal coloboma and other types of ocular coloboma in RCS rats. Both eyes of RCS rats were examined clinically, and those with inferior ectopic pupils underwent morphologic and morphometric examinations. In a prenatal study, coronal serial sections of eyeballs from fetuses at gestational day 16.5 were examined by using light microscopy. Ectopic pupils in RCS rats were found exclusively in an inferior position, where the iris was shortened. Fundic examination revealed severe chorioretinal coloboma in all cases of inferior ectopic pupil. The morphologic characteristics closely resembled those of chorioretinal coloboma in humans. Histopathologic examination of primordia showed incomplete closure of the optic fissure in 4 eyeballs of RCS fetuses. Neither F(1) rats nor N(2) (progeny of RCS × BN matings) displayed any ocular anomalies, including ectopic pupils. The RCS strain is a suitable model for human ocular coloboma, and inferior ectopic pupil appears to be a strong indicator of ocular coloboma.

Aerodynamic Interactions of Propulsive Deceleration and Reaction Control System Jets on Mars-Entry Aeroshells

Science.gov (United States)

Alkandry, Hicham

Future missions to Mars, including sample-return and human-exploration missions, may require alternative entry, descent, and landing technologies in order to perform pinpoint landing of heavy vehicles. Two such alternatives are propulsive deceleration (PD) and reaction control systems (RCS). PD can slow the vehicle during Mars atmospheric descent by directing thrusters into the incoming freestream. RCS can provide vehicle control and steering by inducing moments using thrusters on the hack of the entry capsule. The use of these PD and RCS jets, however, involves complex flow interactions that are still not well understood. The fluid interactions induced by PD and RCS jets for Mars-entry vehicles in hypersonic freestream conditions are investigated using computational fluid dynamics (CFD). The effects of central and peripheral PD configurations using both sonic and supersonic jets at various thrust conditions are examined in this dissertation. The RCS jet is directed either parallel or transverse to the freestream flow at different thrust conditions in order to examine the effects of the thruster orientation with respect to the center of gravity of the aeroshell. The physical accuracy of the computational method is also assessed by comparing the numerical results with available experimental data. The central PD configuration decreases the drag force acting on the entry capsule due to a shielding effect that prevents mass and momentum in the hypersonic freestream from reaching the aeroshell. The peripheral PD configuration also decreases the drag force by obstructing the flow around the aeroshell and creating low surface pressure regions downstream of the PD nozzles. The Mach number of the PD jets, however, does not have a significant effect on the induced fluid interactions. The reaction control system also alters the flowfield, surface, and aerodynamic properties of the aeroshell, while the jet orientation can have a significant effect on the control effectiveness

Structural Basis for DNA Recognition by the Two-Component Response Regulator RcsB.

Science.gov (United States)

Filippova, Ekaterina V; Zemaitaitis, Bozena; Aung, Theint; Wolfe, Alan J; Anderson, Wayne F

2018-02-27

RcsB is a highly conserved transcription regulator of the Rcs phosphorelay system, a complex two-component signal transduction system (N. Majdalani and S. Gottesman, Annu Rev Microbiol 59:379-405, 2005; A. J. Wolfe, Curr Opin Microbiol 13:204-209, 2010, https://doi.org/10.1016/j.mib.2010.01.002; D. J. Clarke, Future Microbiol 5:1173-1184, 2010, https://doi.org/10.2217/fmb.10.83). RcsB plays an important role in virulence and pathogenicity in human hosts by regulating biofilm formation. RcsB can regulate transcription alone or together with its auxiliary transcription regulators by forming heterodimers. This complexity allows RcsB to regulate transcription of more than 600 bacterial genes in response to different stresses (D. Wang et al., Mol Plant Microbe Interact 25:6-17, 2012, https://doi.org/10.1094/MPMI-08-11-0207). Despite increasing knowledge of RcsB importance, molecular mechanisms that drive the ability of RcsB to control transcription of a large number of genes remain unclear. Here, we present crystal structures of unphosphorylated RcsB in complex with the consensus DNA-binding sequence of 22-mer (DNA22) and 18-mer (DNA18) of the flhDC operon from Escherichia coli determined at 3.15- and 3.37-Å resolution, respectively. The results of our structural analysis combined with the results of in vitro binding assays provide valuable insights to the protein regulatory mechanism, demonstrate how RcsB recognizes target DNA sequences, and reveal a unique oligomeric state that allows RcsB to form homo- and heterodimers. This information will help us understand the complex mechanisms of transcriptional regulation by RcsB in bacteria. IMPORTANCE RcsB is a well-studied two-component response regulator of the Rcs phosphorelay system, conserved within the family Enterobacteriaceae , which includes many pathogens. It is a global regulator, controlling more than 5% of bacterial genes associated with capsule biosynthesis, flagellar biogenesis, cell wall biosynthesis

Thermographic Inspections And The Residential Conservation Service Program (RCS)

Science.gov (United States)

Ward, Ronald J.

1983-03-01

Rhode Islanders Saving Energy (RISE) is a non-profit corporation founded in 1977 to provide Rhode Island residents with a variety of energy conservation services. Since January of 1981, it has been performing energy audits in compliance with the Department of Energy's (DOE) Residential Conservation Service Program (RCS). One aspect of the RCS program is the performance of inspections on energy conservation activities completed according to RCS installation guidelines. This paper will describe both the use and results of thermographic inspections within the RISE program. The primary objective of these inspections has been to assure the quality of the building envelope after completion of retrofit measures. Thermal anamolies have been detected that vary in size, location and probable cause. Approximately 37% of all jobs performed through RISE in conjunction with the RCS program have required remedial work as a result of problems that were identi-fied during the thermographic inspection. This percentage was much higher when infra-red inspections were conducted on "Non-RCS" retrofits. Statistics will be presented that provide an interesting insight on the quality of retrofit work when performed in associa-tion with a constant inspection process.

RCS Diversity of Electromagnetic Wave Carrying Orbital Angular Momentum.

Science.gov (United States)

Zhang, Chao; Chen, Dong; Jiang, Xuefeng

2017-11-13

An electromagnetic (EM) wave with orbital angular momentum (OAM) has a helical wave front, which is different from that of the plane wave. The phase gradient can be found perpendicular to the direction of propagation and proportional to the number of OAM modes. Herein, we study the backscattering property of the EM wave with different OAM modes, i.e., the radar cross section (RCS) of the target is measured and evaluated with different OAM waves. As indicated by the experimental results, different OAM waves have the same RCS fluctuation for the simple target, e.g., a small metal ball as the target. However, for complicated targets, e.g., two transverse-deployed small metal balls, different RCSs can be identified from the same incident angle. This valuable fact helps to obtain RCS diversity, e.g., equal gain or selective combining of different OAM wave scattering. The majority of the targets are complicated targets or expanded targets; the RCS diversity can be utilized to detect a weak target traditionally measured by the plane wave, which is very helpful for anti-stealth radar to detect the traditional stealth target by increasing the RCS with OAM waves.

A Novel Low RCS Design Method for X-Band Vivaldi Antenna

Directory of Open Access Journals (Sweden)

XiaoXiang He

2012-01-01

Full Text Available A novel low radar cross-section (RCS design method is proposed, and its application on Vivaldi antenna that covers the entire X band is investigated. According to the difference of the current distribution on the radiator when the antenna radiates or scatters, the shape of the metal radiator is modified, so that maximally 19.2 dBsm RCS reduction is achieved which satisfied radiation performance. Simulated and measured results about gain, S11, and RCS are presented. As a result, the effectiveness of the presented low RCS design method is validated.

Conformational dynamism for DNA interaction in the Salmonella RcsB response regulator.

Science.gov (United States)

Casino, Patricia; Miguel-Romero, Laura; Huesa, Juanjo; García, Pablo; García-Del Portillo, Francisco; Marina, Alberto

2018-01-09

The RcsCDB phosphorelay system controls an extremely large regulon in Enterobacteriaceae that involves processes such as biofilm formation, flagella production, synthesis of extracellular capsules and cell division. Therefore, fine-tuning of this system is essential for virulence in pathogenic microorganisms of this group. The final master effector of the RcsCDB system is the response regulator (RR) RcsB, which activates or represses multiple genes by binding to different promoter regions. This regulatory activity of RcsB can be done alone or in combination with additional transcriptional factors in phosphorylated or dephosphorylated states. The capacity of RcsB to interact with multiple promoters and partners, either dephosphorylated or phosphorylated, suggests an extremely conformational dynamism for this RR. To shed light on the activation mechanism of RcsB and its implication on promoter recognition, we solved the crystal structure of full-length RcsB from Salmonella enterica serovar Typhimurium in the presence and absence of a phosphomimetic molecule BeF3-. These two novel structures have guided an extensive site-directed mutagenesis study at the structural and functional level that confirms RcsB conformational plasticity and dynamism. Our data allowed us to propose a β5-T switch mechanism where phosphorylation is coupled to alternative DNA binding ways and which highlights the conformational dynamism of RcsB to be so pleiotropic. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Characterization of Aerodynamic Interactions with the Mars Science Laboratory Reaction Control System Using Computation and Experiment

Science.gov (United States)

Schoenenberger, Mark; VanNorman, John; Rhode, Matthew; Paulson, John

2013-01-01

On August 5 , 2012, the Mars Science Laboratory (MSL) entry capsule successfully entered Mars' atmosphere and landed the Curiosity rover in Gale Crater. The capsule used a reaction control system (RCS) consisting of four pairs of hydrazine thrusters to fly a guided entry. The RCS provided bank control to fly along a flight path commanded by an onboard computer and also damped unwanted rates due to atmospheric disturbances and any dynamic instabilities of the capsule. A preliminary assessment of the MSL's flight data from entry showed that the capsule flew much as predicted. This paper will describe how the MSL aerodynamics team used engineering analyses, computational codes and wind tunnel testing in concert to develop the RCS system and certify it for flight. Over the course of MSL's development, the RCS configuration underwent a number of design iterations to accommodate mechanical constraints, aeroheating concerns and excessive aero/RCS interactions. A brief overview of the MSL RCS configuration design evolution is provided. Then, a brief description is presented of how the computational predictions of RCS jet interactions were validated. The primary work to certify that the RCS interactions were acceptable for flight was centered on validating computational predictions at hypersonic speeds. A comparison of computational fluid dynamics (CFD) predictions to wind tunnel force and moment data gathered in the NASA Langley 31-Inch Mach 10 Tunnel was the lynch pin to validating the CFD codes used to predict aero/RCS interactions. Using the CFD predictions and experimental data, an interaction model was developed for Monte Carlo analyses using 6-degree-of-freedom trajectory simulation. The interaction model used in the flight simulation is presented.

Effect of natural circulation on RCS depressurization strategy in PWR NPP

International Nuclear Information System (INIS)

Zhang Kun; Tong Lili; Cao Xuewu

2009-01-01

The natural circulation model of Chinese Qinshan Nuclear Power Plant (NPP) Unit 2 is built using SCDAP/RELAP5 code. Selecting TMLB' accident as the base sequence, this paper analyzes the natural circulation phenomena in high-pressure core melt severe accident. In order to study the effect of natural circulation on RCS depressurization strategy, the accident progressions of RCS depressurization with and without natural circulation are simulated, respectively. According to the results, the natural circulation can delay the initiation of RCS depressurization and the whole accident progression, but it does not evidently influence the results of RCS depressurization. (authors)

The Rcs regulon in Proteus mirabilis: implications for motility, biofilm formation, and virulence.

Science.gov (United States)

Howery, Kristen E; Clemmer, Katy M; Rather, Philip N

2016-11-01

The overall role of the Rcs phosphorelay in Proteus mirabilis is largely unknown. Previous work had demonstrated that the Rcs phosphorelay represses the flhDC operon and activates the minCDE cell division inhibition system. To identify additional cellular functions regulated by the Rcs phosphorelay, an analysis of RNA-seq data was undertaken. In this report, the results of the RNA-sequencing are discussed with an emphasis on the predicted roles of the Rcs phosphorelay in swarmer cell differentiation, motility, biofilm formation, and virulence. RcsB is shown to activate genes important for differentiation and fimbriae formation, while repressing the expression of genes important for motility and virulence. Additionally, to follow up on the RNA-Seq data, we demonstrate that an rcsB mutant is deficient in its ability to form biofilm and exhibits enhanced virulence in a Galleria mellonella waxworm model. Overall, these results indicate the Rcs regulon in P. mirabilis extends beyond flagellar genes to include those involved in biofilm formation and virulence. Furthermore, the information presented in this study may provide clues to additional roles of the Rcs phosphorelay in other members of the Enterobacteriaceae.

Conformational heterogeneity of the bacteriopheophytin electron acceptor HA in reaction centers from Rhodopseudomonas viridis revealed by Fourier transform infrared spectroscopy and site-directed mutagenesis.

Science.gov (United States)

Breton, J; Bibikova, M; Oesterhelt, D; Nabedryk, E

1999-08-31

The light-induced Fourier transform infrared (FTIR) difference spectra corresponding to the photoreduction of either the HA bacteriopheophytin electron acceptor (HA-/HA spectrum) or the QA primary quinone (QA-/QA spectrum) in photosynthetic reaction centers (RCs) of Rhodopseudomonas viridis are reported. These spectra have been compared for wild-type (WT) RCs and for two site-directed mutants in which the proposed interactions between the carbonyls on ring V of HA and the RC protein have been altered. In the mutant EQ(L104), the putative hydrogen bond between the protein and the 9-keto C=O of HA should be affected by changing Glu L104 to a Gln. In the mutant WF(M250), the van der Waals interactions between Trp M250 and the 10a-ester C=O of HA should be modified. The characteristic effects of both mutations on the FTIR spectra support the proposed interactions and allow the IR modes of the 9-keto and 10a-ester C=O of HA and HA- to be assigned. Comparison of the HA-/HA and QA-/QA spectra leads us to conclude that the QA-/QA IR signals in the spectral range above 1700 cm-1 are largely dominated by contributions from the electrostatic response of the 10a-ester C=O mode of HA upon QA photoreduction. A heterogeneity in the conformation of the 10a-ester C=O mode of HA in WT RCs, leading to three distinct populations of HA, appears to be related to differences in the hydrogen-bonding interactions between the carbonyls of ring V of HA and the RC protein. The possibility that this structural heterogeneity is related to the observed multiexponential kinetics of electron transfer and the implications for primary processes are discussed. The effect of 1H/2H exchange on the QA-/QA spectra of the WT and mutant RCs shows that neither Glu L104 nor any other exchangeable carboxylic residue changes appreciably its protonation state upon QA reduction.

Radar Cross Section (RCS) Simulation for Wind Turbines

Science.gov (United States)

2013-06-01

wind turbines are unsafe to operate. Also, helical wind turbines generally have less environmental concerns such as killing birds , especially in...SECTION (RCS) SIMULATION FOR WIND TURBINES by Cuong Ton June 2013 Thesis Advisor: David C. Jenn Second Reader: Ric Romero THIS PAGE...TITLE AND SUBTITLE RADAR CROSS SECTION (RCS) SIMULATION FOR WIND TURBINES 5. FUNDING NUMBERS 6. AUTHOR(S) Cuong Ton 7. PERFORMING ORGANIZATION

Ultra-wideband RCS reduction using novel configured chessboard metasurface

International Nuclear Information System (INIS)

Zhuang Ya-Qiang; Wang Guang-Ming; Xu He-Xiu

2017-01-01

A novel artificial magnetic conductor (AMC) metasurface is proposed with ultra-wideband 180° phase difference for radar cross section (RCS) reduction. It is composed of two dual-resonant AMC cells, which enable a broadband phase difference of 180°±30° from 7.9 GHz to 19.2 GHz to be achieved. A novel strategy is devised by dividing each rectangular grid in a chessboard configuration into four triangular grids, leading to a further reduction of peak bistatic RCS. Both full-wave simulation and measurement results show that the proposed metasurface presents a good RCS reduction property over an ultra-wideband frequency range. (paper)

Activation of retinal stem cells in the proliferating marginal region of RCS rats during development of retinitis pigmentosa.

Science.gov (United States)

Jian, Qian; Xu, Haiwei; Xie, Hanping; Tian, Chunyu; Zhao, Tongtao; Yin, ZhengQin

2009-11-06

Retinal stem cells (RSCs) have been demonstrated at the proliferating marginal regions from the pars plana of ciliary body to the ciliary marginal zone (CMZ) in adult lower vertebrates and mammals. Investigations in the lower vertebrates have provided some evidence that RSCs can proliferate following retinal damage; however, the evidence that this occurs in mammals is not clear. In this study, we explored RSCs proliferation potential of adult mammalian in proliferating marginal regions of Royal College of Surgeons (RCS) rats, an animal model for retinitis pigmentosa (RP). The proliferation was evaluated using BrdU labeling, and Chx-10 as markers to discern progenitor cell of CMZ in Long-Evan's and RCS rats at different postnatal day (PND) after eye opening. We found that few Chx-10 and BrdU labeled cells in the proliferating marginal regions of Long-Evan's rats, which significantly increased in RCS rats at PND30 and PND60. Consistent with this, Chx-10/Vimentin double staining cells in the center retina of RCS rats increased significantly at PND30 after eye opening. In addition, mRNA expression of Shh, Ptch1 and Smo was up-regulated in RCS rats at PND60 compared to age-matched Long-Evan's rats, which revealed Shh/ptc pathway involving in the activation of RSCs. These results suggest that RSCs in the mammalian retinal proliferating marginal regions has the potential to regenerate following degeneration.

Preliminary Research on RCS Using DGTD

Directory of Open Access Journals (Sweden)

Yang Qian

2015-06-01

Full Text Available Discontinuous Galerkin Time Domain (DGTD method appears to be very promising which combines the advantages of unstructured mesh in Finite Element Time Domain (FETD and explicit scheme in Finite Difference Time Domain (FDTD. This paper first describes principle of DGTD base on vector basis function. Secondly, Specific method for incident plane wave is given for scattering problem. At last, the monostatic Radar Cross Section (RCS of PEC sphere, medium sphere and the PEC bullet are computed by DGTD method. The numerical results illustrate the feasibility and correctness of the presented scheme. The study of this paper is a foundation for analyzing the RCS of complex target.

STS-46 Atlantis', OV-104's, vertical tail and OMS pods lit up by RCS jet firing

Science.gov (United States)

1992-01-01

STS-46 Atlantis', Orbiter Vehicle (OV) 104's, vertical tail and orbital maneuvering system (OMS) pods are highlighted by the glow of the reaction control system (RCS) jet firings. OV-104 was at an altitude of 128 nautical miles. The remote manipulator system (RMS) arm is partially visible stowed along the port side sill longeron.

Metasurface base on uneven layered fractal elements for ultra-wideband RCS reduction

Science.gov (United States)

Su, Jianxun; Cui, Yueyang; Li, Zengrui; Yang, Yaoqing Lamar; Che, Yongxing; Yin, Hongcheng

2018-03-01

A novel metasurface based on uneven layered fractal elements is designed and fabricated for ultra-wideband radar cross section (RCS) reduction in this paper. The proposed metasurface consists of two fractal subwavelength elements with different layer thickness. The reflection phase difference of 180° (±37°) between two unit cells covers an ultra-wide frequency range. Ultra-wideband RCS reduction results from the phase cancellation between two local waves produced by these two unit cells. The diffuse scattering of electromagnetic (EM) waves is caused by the randomized phase distribution, leading to a low monostatic and bistatic RCS simultaneously. This metasurface can achieve -10dB RCS reduction in an ultra-wide frequency range from 6.6 to 23.9 GHz with a ratio bandwidth (fH/fL) of 3.62:1 under normal incidences for both x- and y-polarized waves. Both the simulation and the measurement results are consistent to verify this excellent RCS reduction performance of the proposed metasurface.

A Multiple Model SNR/RCS Likelihood Ratio Score for Radar-Based Feature-Aided Tracking

National Research Council Canada - National Science Library

Slocumb, Benjamin J; Klusman, III, Michael E

2005-01-01

...) and radar cross section (RCS) for use in narrowband radar tracking. The formulation requires an estimate of the target mean RCS, and a key challenge is the tracking of the mean RCS through significant jumps due to aspect dependencies...

Summary of LO2/Ethanol OMS/RCS Technology and Advanced Development 99-2744

Science.gov (United States)

Curtis, Leslie A.; Hurlbert, Eric A.

1999-01-01

NASA is pursuing non-toxic propellant technologies applicable to RLV and Space Shuttle orbital maneuvering system (OMS) and reaction control system (RCS). The primary objectives of making advancements in an OMS/RCS system are improved safety, reliability, and reduced operations and maintenance cost, while meeting basic operational and performance requirements. An OMS/RCS has a high degree of direct interaction with the vehicle and crew and requires subsystem and components that are compatible with integration into the vehicle with regard to external mold-line, power, and thermal control. In July 1997, a Phase I effort for the technology and advanced development of an upgrade of the space shuttle was conducted to define the system architecture, propellant tank, feed system, RCS thrusters, and OMS engine. Phase I of the project ran from July 1997 to October 1998. Phase II is currently being planned for the development and test of full-scale prototype of the system in 1999 and 2000. The choice of pressure-fed liquid oxygen (LO2) and ethanol is the result of numerous trade studies conducted from 1980 to 1996. Liquid oxygen and ethanol are clean burning, high-density propellants that provide a high degree of commonality with other spacecraft subsystems including life support, power, and thermal control, and with future human exploration and development of space missions. The key to this pressure-fed system is the use of subcooled liquid oxygen at 350 psia. In this approach, there is 80 degrees R of subcooling, which means that boil-off will not occur until the temperature has risen 80 R. The sub-cooling results naturally from loading propellants at 163 R, which is the saturation temperature at 14.7 psia, and then pressurizing to 350 psia on the launch pad. Thermal insulation and conditioning techniques are then used to limit the LO2 temperature to 185 R maximum, and maintain the sub-cooling. The other key is the wide temperature range of ethanol, -173 F to +300 F, which

Evaluation of High-Pressure RCS Natural Circulations Under Severe Accident Conditions

International Nuclear Information System (INIS)

Lee, Byung Chul; Bang, Young Suk; Suh, Nam Duk

2006-01-01

Since TMI-2 accident, the occurrence of severe accident natural circulations inside RCS during entire in-vessel core melt progressions before the reactor vessel breach had been emphasized and tried to clarify its thermal-hydraulic characteristics. As one of consolidated outcomes of these efforts, sophisticated models have been presented to explain the effects of a variety of engineering and phenomenological factors involved during severe accident mitigation on the integrity of RCS pressure boundaries, i.e. reactor pressure vessel(RPV), RCS coolant pipe and steam generator tubes. In general, natural circulation occurs due to density differences, which for single phase flow, is typically generated by temperature differences. Three natural circulation flows can be formed during severe accidents: in-vessel, hot leg countercurrent flow and flow through the coolant loops. Each of these flows may be present during high-pressure transients such as station blackout (SBO) and total loss of feedwater (TLOFW). As a part of research works in order to contribute on the completeness of severe accident management guidance (SAMG) in domestic plants by quantitatively assessing the RCS natural circulations on its integrity, this study presents basic approach for this work and some preliminary results of these efforts with development of appropriately detailed RCS model using MELCOR computer code

Mathematical Model of Synthesis Catalyst with Local Reaction Centers

Directory of Open Access Journals (Sweden)

I. V. Derevich

2017-01-01

Full Text Available The article considers a catalyst granule with a porous ceramic passive substrate and point active centers on which an exothermic synthesis reaction occurs. A rate of the chemical reaction depends on the temperature according to the Arrhenius law. Heat is removed from the pellet surface in products of synthesis due to heat transfer. In our work we first proposed a model for calculating the steady-state temperature of a catalyst pellet with local reaction centers. Calculation of active centers temperature is based on the idea of self-consistent field (mean-field theory. At first, it is considered that powers of the reaction heat release at the centers are known. On the basis of the found analytical solution, which describes temperature distribution inside the granule, the average temperature of the reaction centers is calculated, which then is inserted in the formula for heat release. The resulting system of transcendental algebraic equations is transformed into a system of ordinary differential equations of relaxation type and solved numerically to achieve a steady-state value. As a practical application, the article considers a Fischer-Tropsch synthesis catalyst granule with active cobalt metallic micro-particles. Cobalt micro-particles are the centers of the exothermic reaction of hydrocarbons macromolecular synthesis. Synthesis occurs as a result of absorption of the components of the synthesis gas on metallic cobalt. The temperature distribution inside the granule for a single local center and reaction centers located on the same granule diameter is found. It was found that there is a critical temperature of reactor exceeding of which leads to significant local overheating of the centers - thermal explosion. The temperature distribution with the local reaction centers is qualitatively different from the granule temperature, calculated in the homogeneous approximation. It is shown that, in contrast to the homogeneous approximation, the

RCS estimation of linear and planar dipole phased arrays approximate model

CERN Document Server

Singh, Hema; Jha, Rakesh Mohan

2016-01-01

In this book, the RCS of a parallel-fed linear and planar dipole array is derived using an approximate method. The signal propagation within the phased array system determines the radar cross section (RCS) of phased array. The reflection and transmission coefficients for a signal at different levels of the phased-in scattering array system depend on the impedance mismatch and the design parameters. Moreover the mutual coupling effect in between the antenna elements is an important factor. A phased array system comprises of radiating elements followed by phase shifters, couplers, and terminating load impedance. These components lead to respective impedances towards the incoming signal that travels through them before reaching receive port of the array system. In this book, the RCS is approximated in terms of array factor, neglecting the phase terms. The mutual coupling effect is taken into account. The dependence of the RCS pattern on the design parameters is analyzed. The approximate model is established as a...

A Disulfide Bond in the Membrane Protein IgaA Is Essential for Repression of the RcsCDB System

Directory of Open Access Journals (Sweden)

M. Graciela Pucciarelli

2017-12-01

Full Text Available IgaA is an integral inner membrane protein that was discovered as repressor of the RcsCDB phosphorelay system in the intracellular pathogen Salmonella enterica serovar Typhimurium. The RcsCDB system, conserved in many members of the family Enterobacteriaceae, regulates expression of varied processes including motility, biofilm formation, virulence and response to envelope stress. IgaA is an essential protein to which, in response to envelope perturbation, the outer membrane lipoprotein RcsF has been proposed to bind in order to activate the RcsCDB phosphorelay. Envelope stress has also been reported to be sensed by a surface exposed domain of RcsF. These observations support a tight control of the RcsCDB system by RcsF and IgaA via mechanisms that, however, remain unknown. Interestingly, RcsF and IgaA have four conserved cysteine residues in loops exposed to the periplasmic space. Two non-consecutive disulfide bonds were shown to be required for RcsF function. Here, we report mutagenesis studies supporting the presence of one disulfide bond (C404-C425 in the major periplasmic loop of IgaA that is essential for repression of the RcsCDB phosphorelay. Our data therefore suggest that the redox state of the periplasm may be critical for the control of the RcsCDB system by its two upstream regulators, RcsF and IgaA.

Expression of nitric oxide synthase during the development of RCS rat retinas.

Science.gov (United States)

Sharma, R K; Warfvinge, K; Ehinger, B

2001-01-01

Nitric oxide (NO) has been reported to be both neurodestructive and neuroprotective in the central nervous system and could possibly play an important role in neurodegenerative disorders. On the assumption that NO synthesis may influence degenerative processes in the retina, we have examined the development and distribution of nitric-oxide-synthase(NOS)-immunoreactive cells in developing Royal College of Surgeons (RCS) rat retinas, which is an animal model for retinal degeneration. An antibody against constitutive neuronal NOS was used for immunocytochemistry on RCS rat retinas from postnatal (PN) days 3, 7, 10, 14, 35, 70 and 281 and compared with that in the normal rats of PN days 3, 7, 10, 14, 54 and adults. Immunoreactive cells were not seen in PN 3 retinas but were distinctly seen in the PN 7 retina along with a plexus in the inner plexiform layer. In both groups (normal and RCS rats) a distinct sublayering of the plexus in the inner plexiform layer could be seen at PN 10, which became more distinct at PN 14. The immunoreactive cells were detected also in the oldest retina examined, which was PN 281 in the case of RCS rats. In both groups, certain amacrine cells, certain bipolar cells and certain horizontal cells were found to be immunoreactive. In conclusion, the developmental timetable of the NOS immunoreactivity was identical in the normal and the RCS rat retinas. The NOS-immunoreactive cells persisted in the RCS retinas even when the retina had degenerated extensively. Abnormalities with the inducible isoforms of NOS cannot be ruled out from this study. We conclude that the chronological and qualitative development of the constitutive neuronal NOS immunoreactivity is normal in RCS rat retinas. Copyright 2001 S. Karger AG, Basel

An efficient hybrid technique in RCS predictions of complex targets at high frequencies

Science.gov (United States)

Algar, María-Jesús; Lozano, Lorena; Moreno, Javier; González, Iván; Cátedra, Felipe

2017-09-01

Most computer codes in Radar Cross Section (RCS) prediction use Physical Optics (PO) and Physical theory of Diffraction (PTD) combined with Geometrical Optics (GO) and Geometrical Theory of Diffraction (GTD). The latter approaches are computationally cheaper and much more accurate for curved surfaces, but not applicable for the computation of the RCS of all surfaces of a complex object due to the presence of caustic problems in the analysis of concave surfaces or flat surfaces in the far field. The main contribution of this paper is the development of a hybrid method based on a new combination of two asymptotic techniques: GTD and PO, considering the advantages and avoiding the disadvantages of each of them. A very efficient and accurate method to analyze the RCS of complex structures at high frequencies is obtained with the new combination. The proposed new method has been validated comparing RCS results obtained for some simple cases using the proposed approach and RCS using the rigorous technique of Method of Moments (MoM). Some complex cases have been examined at high frequencies contrasting the results with PO. This study shows the accuracy and the efficiency of the hybrid method and its suitability for the computation of the RCS at really large and complex targets at high frequencies.

Quinone reduction via secondary B-branch electron transfer in mutant bacterial reaction centers.

Science.gov (United States)

Laible, Philip D; Kirmaier, Christine; Udawatte, Chandani S M; Hofman, Samuel J; Holten, Dewey; Hanson, Deborah K

2003-02-18

Symmetry-related branches of electron-transfer cofactors-initiating with a primary electron donor (P) and terminating in quinone acceptors (Q)-are common features of photosynthetic reaction centers (RC). Experimental observations show activity of only one of them-the A branch-in wild-type bacterial RCs. In a mutant RC, we now demonstrate that electron transfer can occur along the entire, normally inactive B-branch pathway to reduce the terminal acceptor Q(B) on the time scale of nanoseconds. The transmembrane charge-separated state P(+)Q(B)(-) is created in this manner in a Rhodobacter capsulatus RC containing the F(L181)Y-Y(M208)F-L(M212)H-W(M250)V mutations (YFHV). The W(M250)V mutation quantitatively blocks binding of Q(A), thereby eliminating Q(B) reduction via the normal A-branch pathway. Full occupancy of the Q(B) site by the native UQ(10) is ensured (without the necessity of reconstitution by exogenous quinone) by purification of RCs with the mild detergent, Deriphat 160-C. The lifetime of P(+)Q(B)(-) in the YFHV mutant RC is >6 s (at pH 8.0, 298 K). This charge-separated state is not formed upon addition of competitive inhibitors of Q(B) binding (terbutryn or stigmatellin). Furthermore, this lifetime is much longer than the value of approximately 1-1.5 s found when P(+)Q(B)(-) is produced in the wild-type RC by A-side activity alone. Collectively, these results demonstrate that P(+)Q(B)(-) is formed solely by activity of the B-branch carriers in the YFHV RC. In comparison, P(+)Q(B)(-) can form by either the A or B branches in the YFH RC, as indicated by the biexponential lifetimes of approximately 1 and approximately 6-10 s. These findings suggest that P(+)Q(B)(-) states formed via the two branches are distinct and that P(+)Q(B)(-) formed by the B side does not decay via the normal (indirect) pathway that utilizes the A-side cofactors when present. These differences may report on structural and energetic factors that further distinguish the functional

The three-dimensional structures of bacterial reaction centers.

Science.gov (United States)

Olson, T L; Williams, J C; Allen, J P

2014-05-01

This review presents a broad overview of the research that enabled the structure determination of the bacterial reaction centers from Blastochloris viridis and Rhodobacter sphaeroides, with a focus on the contributions from Duysens, Clayton, and Feher. Early experiments performed in the laboratory of Duysens and others demonstrated the utility of spectroscopic techniques and the presence of photosynthetic complexes in both oxygenic and anoxygenic photosynthesis. The laboratories of Clayton and Feher led efforts to isolate and characterize the bacterial reaction centers. The availability of well-characterized preparations of pure and stable reaction centers allowed the crystallization and subsequent determination of the structures using X-ray diffraction. The three-dimensional structures of reaction centers revealed an overall arrangement of two symmetrical branches of cofactors surrounded by transmembrane helices from the L and M subunits, which also are related by the same twofold symmetry axis. The structure has served as a framework to address several issues concerning bacterial photosynthesis, including the directionality of electron transfer, the properties of the reaction center-cytochrome c 2 complex, and the coupling of proton and electron transfer. Together, these research efforts laid the foundation for ongoing efforts to address an outstanding question in oxygenic photosynthesis, namely the molecular mechanism of water oxidation.

An advanced regulator for the helium pressurization systems of the Space Shuttle OMS and RCS

Science.gov (United States)

Wichmann, H.

1973-01-01

The Space Shuttle Orbit Maneuvering System and Reaction Control System are pressure-fed rocket propulsion systems utilizing earth storable hypergolic propellants and featuring engines of 6000 lbs and 900 lbs thrust, respectively. The helium pressurization system requirements for these propulsion systems are defined and the current baseline pressurization systems are described. An advanced helium pressure regulator capable of meeting both OMS and RCS helium pressurization system requirements is presented and its operating characteristics and predicted performance characteristics are discussed.

Detailed evaluation of RCS boundary rupture during high-pressure severe accident sequences

International Nuclear Information System (INIS)

Park, Rae-Joon; Hong, Seong-Wan

2011-01-01

A depressurization possibility of the reactor coolant system (RCS) before a reactor vessel rupture during a high-pressure severe accident sequence has been evaluated for the consideration of direct containment heating (DCH) and containment bypass. A total loss of feed water (TLOFW) and a station blackout (SBO) of the advanced power reactor 1400 (APR 1400) has been evaluated from an initiating event to a creep rupture of the RCS boundary by using the SCDAP/RELAP5 computer code. In addition, intentional depressurization of the RCS using power-operated safety relief valves (POSRVs) has been evaluated. The SCDAPRELAP5 results have shown that the pressurizer surge line broke before the reactor vessel rupture failure, but a containment bypass did not occur because steam generator U tubes did not break. The intentional depressurization of the RCS using POSRV was effective for the DCH prevention at a reactor vessel rupture. (author)

Integrable RCS as a Proposed Replacement for Fermilab Booster

Energy Technology Data Exchange (ETDEWEB)

Eldred, Jeffrey [Fermilab; Valishev, Alexander [Fermilab

2017-03-07

Integrable optics is an innovation in particle accelerator design that potentially enables a greater betatron tune spread and damps collective instabilities. An integrable rapid-cycling synchrotron (RCS) would be an effective replacement for the Fermilab Booster, as part of a plan to reach multi-MW beam power at 120 GeV for the Fermilab high-energy neutrino program. We provide an example integrable lattice with features of a modern RCS - dispersion-free drifts, low momentum compaction factor, superperiodicity, chromaticity correction, bounded beta functions, and separate-function magnets.

Regulation of the Min Cell Division Inhibition Complex by the Rcs Phosphorelay in Proteus mirabilis.

Science.gov (United States)

Howery, Kristen E; Clemmer, Katy M; Şimşek, Emrah; Kim, Minsu; Rather, Philip N

2015-08-01

A key regulator of swarming in Proteus mirabilis is the Rcs phosphorelay, which represses flhDC, encoding the master flagellar regulator FlhD4C2. Mutants in rcsB, the response regulator in the Rcs phosphorelay, hyperswarm on solid agar and differentiate into swarmer cells in liquid, demonstrating that this system also influences the expression of genes central to differentiation. To gain a further understanding of RcsB-regulated genes involved in swarmer cell differentiation, transcriptome sequencing (RNA-Seq) was used to examine the RcsB regulon. Among the 133 genes identified, minC and minD, encoding cell division inhibitors, were identified as RcsB-activated genes. A third gene, minE, was shown to be part of an operon with minCD. To examine minCDE regulation, the min promoter was identified by 5' rapid amplification of cDNA ends (5'-RACE), and both transcriptional lacZ fusions and quantitative real-time reverse transcriptase (qRT) PCR were used to confirm that the minCDE operon was RcsB activated. Purified RcsB was capable of directly binding the minC promoter region. To determine the role of RcsB-mediated activation of minCDE in swarmer cell differentiation, a polar minC mutation was constructed. This mutant formed minicells during growth in liquid, produced shortened swarmer cells during differentiation, and exhibited decreased swarming motility. This work describes the regulation and role of the MinCDE cell division system in P. mirabilis swarming and swarmer cell elongation. Prior to this study, the mechanisms that inhibit cell division and allow swarmer cell elongation were unknown. In addition, this work outlines for the first time the RcsB regulon in P. mirabilis. Taken together, the data presented in this study begin to address how P. mirabilis elongates upon contact with a solid surface. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

On the radar cross section (RCS) prediction of vehicles moving on the ground

Energy Technology Data Exchange (ETDEWEB)

Sabihi, Ahmad [Department of Mathematical Sciences, Sharif University of Technology, Tehran (Iran, Islamic Republic of)

2014-12-10

As readers should be aware, Radar Cross Section depends on the factors such as: Wave frequency and polarization, Target dimension, angle of ray incidence, Target’s material and covering, Type of radar system as monostatic or bistatic, space in which contains target and propagating waves, and etc. Having moved or stationed in vehicles can be effective in RCS values. Here, we investigate effective factors in RCS of moving targets on the ground or sea. Image theory in electromagnetic applies to be taken into account RCS of a target over the ground or sea.

On the radar cross section (RCS) prediction of vehicles moving on the ground

International Nuclear Information System (INIS)

Sabihi, Ahmad

2014-01-01

As readers should be aware, Radar Cross Section depends on the factors such as: Wave frequency and polarization, Target dimension, angle of ray incidence, Target’s material and covering, Type of radar system as monostatic or bistatic, space in which contains target and propagating waves, and etc. Having moved or stationed in vehicles can be effective in RCS values. Here, we investigate effective factors in RCS of moving targets on the ground or sea. Image theory in electromagnetic applies to be taken into account RCS of a target over the ground or sea

Layer-specific blood-flow MRI of retinitis pigmentosa in RCS rats☆

Science.gov (United States)

Li, Guang; Garza, Bryan De La; Shih, Yen-Yu I.; Muir, Eric R.; Duong, Timothy Q.

2013-01-01

The Royal College of Surgeons (RCS) rat is an established animal model of retinitis pigmentosa, a family of inherited retinal diseases which starts with loss of peripheral vision and progresses to eventual blindness. Blood flow (BF), an important physiological parameter, is intricately coupled to metabolic function under normal physiological conditions and is perturbed in many neurological and retinal diseases. This study reports non-invasive high-resolution MRI (44 × 44 × 600 μm) to image quantitative retinal and choroidal BF and layer-specific retinal thicknesses in RCS rat retinas at different stages of retinal degeneration compared with age-matched controls. The unique ability to separate retinal and choroidal BF was made possible by the depth-resolved MRI technique. RBF decreased with progressive retinal degeneration, but ChBF did not change in RCS rats up to post-natal day 90. We concluded that choroidal and retinal circulations have different susceptibility to progressive retinal degeneration in RCS rats. Layer-specific retinal thickness became progressively thinner and was corroborated by histological analysis in the same animals. MRI can detect progressive anatomical and BF changes during retinal degeneration with laminar resolution. PMID:22721720

Layer-specific blood-flow MRI of retinitis pigmentosa in RCS rats.

Science.gov (United States)

Li, Guang; De La Garza, Bryan; Shih, Yen-Yu I; Muir, Eric R; Duong, Timothy Q

2012-08-01

The Royal College of Surgeons (RCS) rat is an established animal model of retinitis pigmentosa, a family of inherited retinal diseases which starts with loss of peripheral vision and progresses to eventual blindness. Blood flow (BF), an important physiological parameter, is intricately coupled to metabolic function under normal physiological conditions and is perturbed in many neurological and retinal diseases. This study reports non-invasive high-resolution MRI (44 × 44 × 600 μm) to image quantitative retinal and choroidal BF and layer-specific retinal thicknesses in RCS rat retinas at different stages of retinal degeneration compared with age-matched controls. The unique ability to separate retinal and choroidal BF was made possible by the depth-resolved MRI technique. RBF decreased with progressive retinal degeneration, but ChBF did not change in RCS rats up to post-natal day 90. We concluded that choroidal and retinal circulations have different susceptibility to progressive retinal degeneration in RCS rats. Layer-specific retinal thickness became progressively thinner and was corroborated by histological analysis in the same animals. MRI can detect progressive anatomical and BF changes during retinal degeneration with laminar resolution. Copyright © 2012 Elsevier Ltd. All rights reserved.

An Ultra-wideband and Polarization-independent Metasurface for RCS Reduction.

Science.gov (United States)

Su, Pei; Zhao, Yongjiu; Jia, Shengli; Shi, Wenwen; Wang, Hongli

2016-02-11

In this paper, an ultra-wideband and polarization-independent metasurface for radar cross section (RCS) reduction is proposed. The unit cell of the metasurface operates in a linear cross-polarization scheme in a broad band. The phase and amplitude of cross-polarized reflection can be separately controlled by its geometry and rotation angle. Based on the diffuse reflection theory, a 3-bit coding metasurface is designed to reduce the RCS in an ultra-wide band. The wideband property of the metasurface benefits from the wideband cross polarization conversion and flexible phase modulation. In addition, the polarization-independent feature of the metasurface is achieved by tailoring the rotation angle of each element. Both the simulated and measured results demonstrate that the proposed metasurface can reduce the RCS significantly in an ultra-wide frequency band for both normal and oblique incidences, which makes it promising in the applications such as electromagnetic cloaking.

The analysis of SCS return momentum effects on the RCS water level during mid-loop operations

Energy Technology Data Exchange (ETDEWEB)

swang Seo, J.; Young Yang, J.; Tack Hwang, S. [Seoul National Univ. (Korea, Republic of)

1995-09-01

An accurate prediction of Reactor Coolant System (RCS) water levels is of importance in the determination of allowable operating range to ensure the safety during the mid-loop operations. However, complex hydraulic phenomena induced by Shutdown Cooling System (SCS) return momentum cause different water levels from those in the loop where the water level indicators are located. This was apparantly observed at the pre-core cold hydro test of the Younggwang Nuclear Unit 3 (YGN 3) in Korea. In this study, in order to analytically understand the effect of the SCS return momentum on the RCS water level and its general trend, a model using one-dimensional momentum equation, hydraulic jump, Bernoulli equation, flow resistance coefficient, and total water volume conservation has been developed to predict the RCS water levels at various RCS locations during the mid-loop conditions and the simulation results were compared with the test data. The analysis shows that the hydraulic jump in the operating cold legs in conjunction with the momentum loss throughout the RCS is the main cause creating the water level differences at various RCS locations. The prediction results provide good explanations for the test data and show the significant effect of the SCS return momentum on the RCS water levels.

The analysis of SCS return momentum effects on the RCS water level during mid-loop operations

International Nuclear Information System (INIS)

swang Seo, J.; Young Yang, J.; Tack Hwang, S.

1995-01-01

An accurate prediction of Reactor Coolant System (RCS) water levels is of importance in the determination of allowable operating range to ensure the safety during the mid-loop operations. However, complex hydraulic phenomena induced by Shutdown Cooling System (SCS) return momentum cause different water levels from those in the loop where the water level indicators are located. This was apparantly observed at the pre-core cold hydro test of the Younggwang Nuclear Unit 3 (YGN 3) in Korea. In this study, in order to analytically understand the effect of the SCS return momentum on the RCS water level and its general trend, a model using one-dimensional momentum equation, hydraulic jump, Bernoulli equation, flow resistance coefficient, and total water volume conservation has been developed to predict the RCS water levels at various RCS locations during the mid-loop conditions and the simulation results were compared with the test data. The analysis shows that the hydraulic jump in the operating cold legs in conjunction with the momentum loss throughout the RCS is the main cause creating the water level differences at various RCS locations. The prediction results provide good explanations for the test data and show the significant effect of the SCS return momentum on the RCS water levels

Transient protective effect of caspase inhibitors in RCS rat.

Science.gov (United States)

Perche, O; Doly, M; Ranchon-Cole, I

2008-03-01

In most retinal degenerations in humans and in animal models, photoreceptor cells die by apoptosis. Although the biochemical features are similar in all apoptotic cells, different molecular events lead the cell to death. In the present study we used a rat model of inherited retinal degeneration, the RCS rats, to investigate the involvement of the proteases, caspases and/or calpains, in photoreceptor apoptosis. In the first experiments, rats were untreated or injected intravitreally at post natal day 27 (P27) with the large broad spectrum caspase inhibitor, ZVAD, the calpain inhibitor, MuhPhe, or with the vehicle, DMSO. Retinal status was evaluated at P35 and P42 by electroretinography, morphometry and apoptotic nuclei detection. DMSO and MuhPhe had no effect on RCS retinas as evidenced by equivalent loss of function and equivalent number of apoptotic cells than in untreated group. ZVAD transiently reduced apoptotic cells and preserved photoreceptor function at P35 but not at P42. These results suggest that caspases but not calpains are involved in retinal degeneration in the RCS. In the second experiments, RCS rats were injected twice at P27 and P35 with ZVAD or DMSO. Although ZVAD-treated retinas were preserved at P35 compared to the DMSO controls, the second injection of ZVAD did not extend the preserving effect to P42. Moreover, a single injection of ZVAD at P35 had no preserving effect at P42. All these data taken together suggest that caspases do not play a pivotal role after P35. In a fourth set of experiments, we used specific caspase inhibitors to elucidate which caspase was activated. The caspase-1/4 inhibitor (YVAD) or the caspase-3/7 inhibitor (DEVD) were injected intravitreally at P27 and retinal status was evaluated at P35 and P42. Electroretinograms and apoptotic nuclei detection demonstrated that YVAD and DEVD preserved photoreceptors at P35 but not at P42. These results suggest that both caspase-1/4 and caspase-3/7 play a major role in the apoptotic

Differences in the use of spirometry between rural and urban primary care centers in Spain.

Science.gov (United States)

Márquez-Martín, Eduardo; Soriano, Joan B; Rubio, Myriam Calle; Lopez-Campos, Jose Luis

2015-01-01

The aim of this study is to evaluate the ability and practice of spirometry, training of technicians, and spirometry features in primary care centers in Spain, evaluating those located in a rural environment against those in urban areas. An observational cross-sectional study was conducted in 2012 by a telephone survey in 970 primary health care centers in Spain. The centers were divided into rural or urban depending on the catchment population. The survey contacted technicians in charge of spirometry and consisted of 36 questions related to the test that included the following topics: center resources, training doctors and technicians, using the spirometer, bronchodilator test, and the availability of spirometry and maintenance. Although the sample size was achieved in both settings, rural centers (RCs) gave a lower response rate than urban centers (UCs). The number of centers without spirometry in rural areas doubled those in the urban areas. Most centers had between one and two spirometers. However, the number of spirometry tests per week was significantly lower in RCs than in UCs (4 [4.1%] vs 6.9 [5.7%], Pspirometries was higher in RCs than in UCs (209 [73.0%] vs 207 [64.2%], P=0.003). RCs were more satisfied with the spirometries (7.8 vs 7.6, P=0.019) and received more training course for interpreting spirometry (41.0% vs 33.2%, P=0.004). The performance of the bronchodilator test showed a homogeneous measure in different ways. The spirometer type and the reference values were unknown to the majority of respondents. This study shows the differences between primary care RCs and UCs in Spain in terms of performing spirometry. The findings in the present study can be used to improve the performance of spirometry in these areas.

Research on the Scattering Characteristics and the RCS Reduction of Circularly Polarized Microstrip Antenna

Directory of Open Access Journals (Sweden)

W. Jiang

2013-01-01

Full Text Available Based on the study of the radiation and scattering of the circularly polarized (CP antenna, a novel radar cross-section (RCS reduction technique is proposed for CP antenna in this paper. Quasi-fractal slots are applied in the design of the antenna ground plane to reduce the RCS of the CP antenna. Both prototype antenna and array are designed, and their time-, frequency-, and space-domain characteristics are studied to authenticate the proposed technique. The simulated and measured results show that the RCS of the prototype antenna and array is reduced up to 7.85 dB and 6.95 dB in the band of 1 GHz–10 GHz. The proposed technique serves a candidate in the design of low RCS CP antennas and arrays.

The Quantitative Reasoning for College Science (QuaRCS) Assessment in non-Astro 101 Courses II

Science.gov (United States)

Kirkman, Thomas W.; Jensen, Ellen

2017-06-01

The Quantitative Reasoning for College Science (QuaRCS) Assessment[1] aims to measure the pre-algebra mathematical skills that are often part of "general education" science courses like Astro 101. In four majors STEM classes, we report comparisons between QuaRCS metrics, ACT math, GPAO, and the course grade. In three of four classes QuaRCS QR score and ACT math were statistically significantly correlated (with r˜.6), however in the fourth course —a senior-level microbiology course— there was no statistically significantly correlation (in fact, rPhysics courses showed fractional sigma gains in QR, self-estimated math fluency and math importance, but not all of those increases were statistically significant. Using a QuaRCS map relating the questions to skill areas, we found graph reading, percentages, and proportional reasoning to be the most misunderstood skills in all four courses.[1] QuaRCS, Follette, et al.,2015, DOI: http://dx.doi.org/10.5038/1936-4660.8.2.2

Enriched reaction center preparation from green photosynthetic bacteria. [Chlorobium limicola

Energy Technology Data Exchange (ETDEWEB)

Olson, J M; Giddings, Jr, T H; Shaw, E K

1976-01-01

Bacteriochlorophyll a reaction-center complex I from Chlorobium limicola f. thiosulfatophilum 6230 (Tassajara) was incubated in 2 M guanidine . HCl and then chromatographed on cross-linked dextran or agarose gel. Two principal components were separated: a larger component with photochemical activity (bacteriochlorophyll a reaction-center complex II) and a smaller component without activity (bacteriochlorophyll a protein). Complex II contains carotenoid, bacteriochlorophyll a, reaction center(s), and cytochromes b and c, but lacks the well characterized bacteriochlorophyll a protein contained in Complex I. Complex II carries out a light-induced reduction of cytochrome b along with an oxidation of cytochrome c.

Dynamic radar cross section measurements of a full-scale aircraft for RCS modelling validation

CSIR Research Space (South Africa)

Van Schalkwyk, Richard F

2017-10-01

Full Text Available In this paper the process followed in generating a high fidelity reference data set for radar cross section (RCS) modelling validation for a full-scale aircraft, is presented. An overview of two dynamic RCS measurement campaigns, involving both...

Bcl-2 expression during the development and degeneration of RCS rat retinae.

Science.gov (United States)

Sharma, R K

2001-12-14

In various hereditary retinal degenerations, including that in Royal College of Surgeons (RCS) rats, the photoreceptors ultimately die by apoptosis. Bcl-2 is one of the genes, which regulates apoptosis and is thought to promote survival of cells. This study has investigated the developmental expression of Bcl-2 in RCS rat, which is a well-studied animal model for hereditary retinal degeneration. An antibody against Bcl-2 was used for its immunohistochemical localization in dystrophic RCS rat retinae from postnatal (PN) days 4, 7, 13, 35, 45, 70, 202 and 14 months. Results were compared with Bcl-2 localization in congenic non-dystrophic rats from PN 4, 7, 13, 44, 202 and 14 months. Bcl-2 immunoreactivity in non-dystrophic retinae was already present in PN 4 retinae in the nerve fiber layer (presumably in the endfeet of immature Müller cells) and in the proximal parts of certain radially aligned neuroepithelial cells/immature Müller cell radial processes. With increasing age the immunoreactivity in relatively more mature Müller cell radial processes spread distally towards the outer retina and between PN 13 and 44 it reached the adult distribution. No cell bodies in the ganglion cell layer were found to be immunoreactive. Expression of Bcl-2 immunoreactivity in dystrophic RCS rat retinae closely resembled that of non-dystrophic retinae. No immunoreactivity was seen in photoreceptors or retinal pigment epithelium in dystrophic or non-dystrophic retinae. In conclusion, Bcl-2 expression is not altered, either in terms of its chronology or the cell type expressing it, during retinal degeneration in RCS rats.

Mars Ascent Vehicle Reaction Control System, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — During this Phase I NASA program, Valley Tech Systems (VTS) will develop an innovative solid Reaction Control System (RCS) architecture concept design that can...

Design Considerations for Proposed Fermilab Integrable RCS

Energy Technology Data Exchange (ETDEWEB)

Eldred, Jeffrey [Fermilab; Valishev, Alexander

2017-03-02

Integrable optics is an innovation in particle accelerator design that provides strong nonlinear focusing while avoiding parametric resonances. One promising application of integrable optics is to overcome the traditional limits on accelerator intensity imposed by betatron tune-spread and collective instabilities. The efficacy of high-intensity integrable accelerators will be undergo comprehensive testing over the next several years at the Fermilab Integrable Optics Test Accelerator (IOTA) and the University of Maryland Electron Ring (UMER). We propose an integrable Rapid-Cycling Synchrotron (iRCS) as a replacement for the Fermilab Booster to achieve multi-MW beam power for the Fermilab high-energy neutrino program. We provide a overview of the machine parameters and discuss an approach to lattice optimization. Integrable optics requires arcs with integer-pi phase advance followed by drifts with matched beta functions. We provide an example integrable lattice with features of a modern RCS - long dispersion-free drifts, low momentum compaction, superperiodicity, chromaticity correction, separate-function magnets, and bounded beta functions.

Subretinally transplanted embryonic stem cells rescue photoreceptor cells from degeneration in the RCS rats.

Science.gov (United States)

Schraermeyer, U; Thumann, G; Luther, T; Kociok, N; Armhold, S; Kruttwig, K; Andressen, C; Addicks, K; Bartz-Schmidt, K U

2001-01-01

The Royal College of Surgeons (RCS) rat is an animal model for retinal degeneration such as the age-related macular degeneration. The RCS rat undergoes a progressive retinal degeneration during the early postnatal period. A potential treatment to prevent this retinal degeneration is the transplantation into the subretinal space of cells that would replace functions of the degenerating retinal pigment epithelium (RPE) cells or may form neurotrophic factors. In this study we have investigated the potential of subretinally transplanted embryonic stem cells to prevent the genetically determined photoreceptor cell degeneration in the RCS rat. Embryonic stem cells from the inner cell mass of the mouse blastocyst were allowed to differentiate to neural precursor cells in vitro and were then transplanted into the subretinal space of 20-day-old RCS rats. Transplanted and sham-operated rats were sacrificed 2 months following cell transplantation. The eyes were enucleated and photoreceptor degeneration was quantified by analyzing and determining the thickness of the outer nuclear layer by light and electron microscopy. In the eyes transplanted with embryonic cells up to 8 rows of photoreceptor cell nuclei were observed, whereas in nontreated control eyes the outer nuclear layer had degenerated completely. Transplantation of embryonic stem cells appears to delay photoreceptor cell degeneration in RCS rats.

Engineering description of the OMS/RCS/DAP modes used in the HP-9825A High Fidelity Relative Motion Program (HFRMP)

Science.gov (United States)

Wilson, S. W.

1978-01-01

Simplified mathematical models are reported for the space shuttle's Orbital Maneuvering System (OMS), Reaction Control System (RCS), and on-orbit Digital Autopilot (DAP) that have been incorporated in the High-Fidelity Relative Motion Program (HFRMP) for the HP-9825A desk-top calculator. Comparisons were made between data generated by the HFRMP and by the Space Shuttle Functional Simulator (SSFS), which models the cited shuttle systems in much greater detail. These data include propellant requirements for representative translational maneuvers, rotational maneuvers, and attitude maintenance options. Also included are data relating to on-orbit trajectory deviations induced by RCS translational cross coupling. Potential close-range stationkeeping problems that are suggested by HFRMP simulations of 80 millisecond (as opposed to 40 millisecond) DAP cycle effects are described. The principal function of the HFRMP is to serve as a flight design tool in the area of proximity operations.

Mutual Coupling Effects for Radar Cross Section (RCS of a Series-Fed Dipole Antenna Array

Directory of Open Access Journals (Sweden)

H. L. Sneha

2012-01-01

Full Text Available The estimation of RCS of a phased array depends on various parameters, namely, array geometry, operational frequency, feed network, mutual coupling between the antenna elements and so fourth. This paper presents the estimation of RCS of linear dipole array with series-feed network by tracing the signal path from the antenna aperture into the feed network. The effect of mutual coupling exhibited by the dipole antenna is considered for three configurations namely, side by side, collinear, and parallel in echelon. It is shown that the mutual coupling affects the antenna pattern (and hence RCS significantly for larger scan angles. Further it is inferred that the RCS of phased array can be optimized by (i reducing the length of the dipole, (ii termination of the isolation port of the coupler with a suitable load, and (iii using suitable amplitude distribution.

Radar cross-section (RCS) analysis of high frequency surface wave radar targets

OpenAIRE

ÇAKIR, Gonca; SEVGİ, Levent

2010-01-01

Realistic high frequency surface wave radar (HFSWR) targets are investigated numerically in terms of electromagnetic wave -- target interactions. Radar cross sections (RCS) of these targets are simulated via both the finite-difference time-domain (FDTD) method and the Method of Moments (MoM). The virtual RCS prediction tool that was introduced in previous work is used for these investigations. The virtual tool automatically creates the discrete FDTD model of the target under investi...

Resident Reactions to Person-Centered Communication by Long-Term Care Staff.

Science.gov (United States)

Savundranayagam, Marie Y; Sibalija, Jovana; Scotchmer, Emma

2016-09-01

Long-term care staff caregivers who are person centered incorporate the life history, preferences, and feelings of residents with dementia during care interactions. Communication is essential for person-centered care. However, little is known about residents' verbal reactions when staff use person-centered communication. Accordingly, this study investigated the impact of person-centered communication and missed opportunities for such communication by staff on resident reactions. Conversations (N = 46) between staff-resident dyads were audio-recorded during routine care tasks over 12 weeks. Staff utterances were coded for person-centered communication and missed opportunities. Resident utterances were coded for positive reactions, such as cooperation, and negative reactions, such as distress. Linear regression analyses revealed that the more staff used person-centered communication, the more likely that residents reacted positively. Additionally, the more missed opportunities in a conversation, the more likely that the residents reacted negatively. Conversation illustrations elaborate on the quantitative findings and implications for staff training are discussed. © The Author(s) 2016.

TMI-2 RCS activity and solids loading from aggressive defueling techniques

International Nuclear Information System (INIS)

Baston, V.F.; Hofstetter, K.J.

1987-01-01

One of the tasks performed in support of defueling operations has involved mechanical degradation of resolidified material (core crust layer) utilizing the core drilling equipment. Prior to actual drilling operations, an engineering estimate was made for the anticipated increase in radioactivity and particulate loading to the Three Mile Island Unit 2 (TMI-2) reactor coolant system (RCS). Predictions for RCS activity and particulate loading increases were important to evaluate the cleanup requirements for the defueling water cleanup system to minimize both the dose rates for defueling personnel and water turbidity

Changes in intrinsic excitability of ganglion cells in degenerated retinas of RCS rats

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Yi-Ming Ren

2018-05-01

Full Text Available AIM: To evaluate the intrinsic excitability of retinal ganglion cells (RGCs in degenerated retinas. METHODS: The intrinsic excitability of various morphologically defined RGC types using a combination of patch-clamp recording and the Lucifer yellow tracer in retinal whole-mount preparations harvested from Royal College of Surgeons (RCS rats, a common retinitis pigmentosa (RP model, in a relatively late stage of retinal degeneration (P90 were investigated. Several parameters of RGC morphologies and action potentials (APs were measured and compared to those of non-dystrophic control rats, including dendritic stratification, dendritic field diameter, peak amplitude, half width, resting membrane potential, AP threshold, depolarization to threshold, and firing rates. RESULTS: Compared with non-dystrophic control RGCs, more depolarizations were required to reach the AP threshold in RCS RGCs with low spontaneous spike rates and in RCS OFF cells (especially A2o cells, and RCS RGCs maintained their dendritic morphologies, resting membrane potentials and capabilities to generate APs. CONCLUSION: RGCs are relatively well preserved morphologically and functionally, and some cells are more susceptible to decreased excitability during retinal degeneration. These findings provide valuable considerations for optimizing RP therapeutic strategies.

Ultra-Wideband RCS Reduction and Gain Enhancement of Aperture-Coupled Antenna Based on Hybrid-FSS

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L. L. Cong

2017-12-01

Full Text Available A novel design of aperture-coupled microstrip antenna with ultra-wideband low radar cross section (RCS is proposed. Hybrid frequency selective surface (FSS structures consisting of two kinds of polarization-dependent folded split ring resonators (PDFSRRs and square patches are utilized to replace the conventional metallic ground. By orthogonally arranging the PDFSRRs in a chessboard-like configuration, the band-stop characteristic contributes to the gain enhancement, while the zero degree points of reflection phase and wave-transmission characteristic are utilized to achieve RCS reduction both in-band and out-of-band. Furthermore, with square patches periodically etched on the bottom of FSS structure, a new zero degree reflection phase is introduced to enhance the effect of RCS reduction. Full wave simulations and measurements demonstrate that the proposed antenna achieves RCS reduction from 1 GHz to 18 GHz and gain enhancement compared with traditional microstrip antenna.

Location Privacy on DVB-RCS using a “Spatial-Timing” Approach

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A. Aggelis

2011-09-01

Full Text Available DVB-RCS synchronization scheme on the Return Channel requires the RCSTs to be programmed with their location coordinates with an accuracy of no more than a few kilometers. RCSTs use this location information in their ranging calculation to the servicing satellite. For certain users this location information disclosure to the network operator can be seen as a serious security event. Recent work of the authors overcame this requirement by cloaking the location of an RCST in such a way (based on "spatial/geometric" symmetries of the network that the respective ranging calculations are not affected. In this work we argue that timing tolerances in the Return Channel synchronization scheme, accepted by the DVB-RCS standard, can be used in combination to the "spatial" method, further enhancing the location privacy of an RCST. Theoretical findings of the proposed "spatial-timing" approach were used to develop a practical method that can be used by workers in the field. Finally this practical method was successfully tested on a real DVB-RCS system.

Systemic administration of erythropoietin inhibits retinopathy in RCS rats.

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Weiyong Shen

Full Text Available OBJECTIVE: Royal College of Surgeons (RCS rats develop vasculopathy as photoreceptors degenerate. The aim of this study was to examine the effect of erythropoietin (EPO on retinopathy in RCS rats. METHODS: Fluorescein angiography was used to monitor retinal vascular changes over time. Changes in retinal glia and vasculature were studied by immunostaining. To study the effects of EPO on retinal pathology, EPO (5000 IU/kg was injected intraperitoneally in 14 week old normal and RCS rats twice a week for 4 weeks. Changes in the retinal vasculature, glia and microglia, photoreceptor apoptosis, differential expression of p75 neurotrophin receptor (p75NTR, pro-neurotrophin 3 (pro-NT3, tumour necrosis factor-α (TNFα, pigment epithelium derived factor (PEDF and vascular endothelial growth factor-A (VEGF-A, the production of CD34(+ cells and mobilization of CD34(+/VEGF-R2(+ cells as well as recruitment of CD34(+ cells into the retina were examined after EPO treatment. RESULTS: RCS rats developed progressive capillary dropout and subretinal neovascularization which were accompanied by retinal gliosis. Systemic administration of EPO stabilized the retinal vasculature and inhibited the development of focal vascular lesions. Further studies showed that EPO modulated retinal gliosis, attenuated photoreceptor apoptosis and p75NTR and pro-NT3 upregulation, promoted the infiltration of ramified microglia and stimulated VEGF-A expression but had little effect on TNFα and PEDF expression. EPO stimulated the production of red and white blood cells and CD34(+ cells along with effective mobilization of CD34(+/VEGF-R2(+ cells. Immunofluorescence study demonstrated that EPO enhanced the recruitment of CD34+ cells into the retina. CONCLUSIONS: Our results suggest that EPO has therapeutic potentials in treatment of neuronal and vascular pathology in retinal disease. The protective effects of EPO on photoreceptors and the retinal vasculature may involve multiple

B-side charge separation in bacterial photosynthetic reaction centers: nanosecond time scale electron transfer from HB- to QB.

Science.gov (United States)

Kirmaier, Christine; Laible, Philip D; Hanson, Deborah K; Holten, Dewey

2003-02-25

We report time-resolved optical measurements of the primary electron transfer reactions in Rhodobacter capsulatus reaction centers (RCs) having four mutations: Phe(L181) --> Tyr, Tyr(M208) --> Phe, Leu(M212) --> His, and Trp(M250) --> Val (denoted YFHV). Following direct excitation of the bacteriochlorophyll dimer (P) to its lowest excited singlet state P, electron transfer to the B-side bacteriopheophytin (H(B)) gives P(+)H(B)(-) in approximately 30% yield. When the secondary quinone (Q(B)) site is fully occupied, P(+)H(B)(-) decays with a time constant estimated to be in the range of 1.5-3 ns. In the presence of excess terbutryn, a competitive inhibitor of Q(B) binding, the observed lifetime of P(+)H(B)(-) is noticeably longer and is estimated to be in the range of 4-8 ns. On the basis of these values, the rate constant for P(+)H(B)(-) --> P(+)Q(B)(-) electron transfer is calculated to be between approximately (2 ns)(-)(1) and approximately (12 ns)(-)(1), making it at least an order of magnitude smaller than the rate constant of approximately (200 ps)(-)(1) for electron transfer between the corresponding A-side cofactors (P(+)H(A)(-) --> P(+)Q(A)(-)). Structural and energetic factors associated with electron transfer to Q(B) compared to Q(A) are discussed. Comparison of the P(+)H(B)(-) lifetimes in the presence and absence of terbutryn indicates that the ultimate (i.e., quantum) yield of P(+)Q(B)(-) formation relative to P is 10-25% in the YFHV RC.

Experimental studies of water hammer in propellant feed system of reaction control system

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Avanish Kumar

2018-03-01

Full Text Available Water hammer pressure transient produces large dynamic forces which can damage the pipes and other assemblies in the feed line of a reaction control system (RCS. It has led to the failure of pressure transducers monitoring the manifold pressure in the feed line of RCS. Therefore, water hammer studies have been carried out to understand its effect in feed line. Feedline system has been simplified to develop a mathematical model and experiments have been carried out at extensive levels. The mathematical model was developed considering pipe of uniform c/s and moving liquid-gas interface. The experimental studies have been done using water as working medium instead of actual propellant. The studies showed that rate of pressurization have a very critical role on the water hammer amplitude. Sensitivity studies have been also carried out to study the effect of density, friction and initial liquid column length on water hammer amplitude. Keywords: Water hammer, Reaction control system (RCS, Propellant feed system, Experimental study, Testing

Dynamic RCS Simulation of a Missile Target Group Based on the High-frequency Asymptotic Method

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Zhao Tao

2014-04-01

Full Text Available To simulate dynamic Radar Cross Section (RCS of missile target group, an efficient RCS prediction approach is proposed based on the high-frequency asymptotic theory. The minimal energy trajectory and coordinate transformation is used to get trajectories of the missile, decoys and roll booster, and establish the dynamic scene for the separate procedure of the target group, and the dynamic RCS including specular reflection, edge diffraction and multi-reflection from the target group are obtained by Physical Optics (PO, Equivalent Edge Currents (EEC and Shooting-and-Bouncing Ray (SBR methods. Compared with the dynamic RCS result with the common interpolation method, the proposed method is consistent with the common method when the targets in the scene are far away from each other and each target is not sheltered by others in the incident direction. When the target group is densely distributed and the shelter effect can not be neglected, the interpolation method is extremely difficult to realize, whereas the proposed method is successful.

Wideband RCS Reduction of Microstrip Array Antenna Based on Absorptive Frequency Selective Surface and Microstrip Resonators

Directory of Open Access Journals (Sweden)

Jingjing Xue

2017-01-01

Full Text Available An approach for wideband radar cross section (RCS reduction of a microstrip array antenna is presented and discussed. The scheme is based on the microstrip resonators and absorptive frequency selective surface (AFSS with a wideband absorptive property over the low band 1.9–7.5 GHz and a transmission characteristic at high frequency 11.05 GHz. The AFSS is designed to realize the out-of-band RCS reduction and preserve the radiation performance simultaneously, and it is placed above the antenna with the operating frequency of 11.05 GHz. Moreover, the microstrip resonators are loaded to obtain the in-band RCS reduction. As a result, a significant RCS reduction from 1.5 GHz to 13 GHz for both types of polarization has been accomplished. Compared with the reference antenna, the simulated results exhibit that the monostatic RCS of the proposed array antenna in x- and y-polarization can be reduced as much as 17.6 dB and 21.5 dB, respectively. And the measured results agree well with the simulated ones.

[Blue-light induced expression of S-adenosy-L-homocysteine hydrolase-like gene in Mucor amphibiorum RCS1].

Science.gov (United States)

Gao, Ya; Wang, Shu; Fu, Mingjia; Zhong, Guolin

2013-09-04

To determine blue-light induced expression of S-adenosyl-L-homocysteine hydrolase-like (sahhl) gene in fungus Mucor amphibiorum RCS1. In the random process of PCR, a sequence of 555 bp was obtained from M. amphibiorum RCS1. The 555 bp sequence was labeled with digoxin to prepare the probe for northern hybridization. By northern hybridization, the transcription of sahhl gene was analyzed in M. amphibiorum RCS1 mycelia culture process from darkness to blue light to darkness. Simultaneously real-time PCR method was used to the sahhl gene expression analysis. Compared with the sequence of sahh gene from Homo sapiens, Mus musculus and some fungi species, a high homology of the 555 bp sequence was confirmed. Therefore, the preliminary confirmation has supported that the 555 bp sequence should be sahhl gene from M. amphibiorum RCS1. Under the dark pre-culture in 24 h, a large amounts of transcript of sahhl gene in the mycelia can be detected by northern hybridization and real-time PCR in the condition of 24 h blue light. But a large amounts of transcript of sahhl gene were not found in other detection for the dark pre-culture of 48 h, even though M. amphibiorum RCS1 mycelia were induced by blue light. Blue light can induce the expression of sahhl gene in the vigorous growth of M. amphibiorum RCS1 mycelia.

Correction of the retinal dystrophy phenotype of the RCS rat by viral gene transfer of Mertk.

Science.gov (United States)

Vollrath, D; Feng, W; Duncan, J L; Yasumura, D; D'Cruz, P M; Chappelow, A; Matthes, M T; Kay, M A; LaVail, M M

2001-10-23

The Royal College of Surgeons (RCS) rat is a widely studied animal model of retinal degeneration in which the inability of the retinal pigment epithelium (RPE) to phagocytize shed photoreceptor outer segments leads to a progressive loss of rod and cone photoreceptors. We recently used positional cloning to demonstrate that the gene Mertk likely corresponds to the retinal dystrophy (rdy) locus of the RCS rat. In the present study, we sought to determine whether gene transfer of Mertk to a RCS rat retina would result in correction of the RPE phagocytosis defect and preservation of photoreceptors. We used subretinal injection of a recombinant replication-deficient adenovirus encoding rat Mertk to deliver the gene to the eyes of young RCS rats. Electrophysiological assessment of animals 30 days after injection revealed an increased sensitivity of treated eyes to low-intensity light. Histologic and ultrastructural assessment demonstrated substantial sparing of photoreceptors, preservation of outer segment structure, and correction of the RPE phagocytosis defect in areas surrounding the injection site. Our results provide definitive evidence that mutation of Mertk underlies the RCS retinal dystrophy phenotype, and that the phenotype can be corrected by treatment of juvenile animals. To our knowledge, this is the first demonstration of complementation of both a functional cellular defect (phagocytosis) and a photoreceptor degeneration by gene transfer to the RPE. These results, together with the recent discovery of MERTK mutations in individuals with retinitis pigmentosa, emphasize the importance of the RCS rat as a model for gene therapy of diseases that arise from RPE dysfunction.

VXIbus-based signal generator for resonant power supply system of the 3 GeV RCS

Energy Technology Data Exchange (ETDEWEB)

Zhang, Fengqing; Watanabe, Yasuhiro; Koseki, Shoichiro; Tani, Norio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Adachi, Toshikazu; Someya, Hirohiko [High Energy Accelerator Reseach Organization, Tsukuba, Ibaraki (Japan)

2002-03-01

The 3 GeV Proton RCS of the JAERI-KEK Joint Project is a 25 Hz separate-function rapid cycling synchrotron under design. Bending magnets (BM) and quadrupole magnets (QM) are excited separately. The 3 GeV RCS requests above 10 families of magnets excited independently, far beyond 3 families in practical RCS's. Difficulty of field tracking between BM and QM is significantly increased. Magnet strings are grouped into resonant networks and excited resonantly with power supplies driven by a waveform pattern, typically a DC-biased sinusoidal signal. To achieve a close tracking between many families, the driving signal of each power supply should be adjusted in phase and amplitude flexibly and dynamically. This report proposes a signal generator based on VXIbus. The VXIbus, an extension of VMEbus (VME eXtensions for Instrument), provides an open architecture with shared process bus and timing. The VXIbus-based signal generator facilitates the timing synchronization and is easy to extend to many channels needed by the 3 GeV RCS. Experimental results of the signal generator are reported. (author)

Conformational regulation of charge recombination reactions in a photosynthetic bacterial reaction center

DEFF Research Database (Denmark)

Katona, Gergely; Snijder, Arjan; Gourdon, Pontus Emanuel

2005-01-01

In bright light the photosynthetic reaction center (RC) of Rhodobacter sphaeroides stabilizes the P(+)(870).Q(-)(A) charge-separated state and thereby minimizes the potentially harmful effects of light saturation. Using X-ray diffraction we report a conformational change that occurs within the cy...... the cytoplasmic domain of this RC in response to prolonged illumination with bright light. Our observations suggest a novel structural mechanism for the regulation of electron transfer reactions in photosynthesis....

Subretinal electrical stimulation preserves inner retinal function in RCS rat retina.

Science.gov (United States)

Ciavatta, Vincent T; Mocko, Julie A; Kim, Moon K; Pardue, Machelle T

2013-01-01

Previously, studies showed that subretinal electrical stimulation (SES) from a microphotodiode array (MPA) preserves electroretinography (ERG) b-wave amplitude and regional retinal structure in the Royal College of Surgeons (RCS) rat and simultaneously upregulates Fgf2 expression. This preservation appears to be associated with the increased current produced when the MPA is exposed to ERG test flashes, as weekly ERG testing produces greater neuroprotection than biweekly or no testing. Using an infrared source to stimulate the MPA while avoiding potential confounding effects from exposing the RCS retina to high luminance white light, this study examined whether neuroprotective effects from SES increased with subretinal current in a dose-dependent manner. RCS rats (n=49) underwent subretinal implantation surgery at P21 with MPA devices in one randomly selected eye, and the other eye served as the control. Naïve RCS rats (n=25) were also studied. To increase SES current levels, implanted eyes were exposed to 15 min per session of flashing infrared light (IR) of defined intensity, frequency, and duty cycle. Rats were divided into four SES groups that received ERG testing only (MPA only), about 450 µA/cm2 once per week (Low 1X), about 450 µA/cm2 three times per week (Low 3X), and about 1350 µA/cm2 once per week (High 1X). One eye of the control animals was randomly chosen for IR exposure. All animals were followed for 4 weeks with weekly binocular ERGs. A subset of the eyes was used to measure retina Fgf2 expression with real-time reverse-transcription PCR. Eyes receiving SES showed significant preservation of b-wave amplitude, a- and b-wave implicit times, oscillatory potential amplitudes, and post-receptoral parameters (Vmax and log σ) compared to untreated eyes. All SES-treated eyes had similar preservation, regardless of increased SES from IR light exposure. SES-treated eyes tended to have greater retinal Fgf2 expression than untreated eyes, but Fgf2 expression

Proteomic profiling of early degenerative retina of RCS rats.

Science.gov (United States)

Zhu, Zhi-Hong; Fu, Yan; Weng, Chuan-Huang; Zhao, Cong-Jian; Yin, Zheng-Qin

2017-01-01

To identify the underlying cellular and molecular changes in retinitis pigmentosa (RP). Label-free quantification-based proteomics analysis, with its advantages of being more economic and consisting of simpler procedures, has been used with increasing frequency in modern biological research. Dystrophic RCS rats, the first laboratory animal model for the study of RP, possess a similar pathological course as human beings with the diseases. Thus, we employed a comparative proteomics analysis approach for in-depth proteome profiling of retinas from dystrophic RCS rats and non-dystrophic congenic controls through Linear Trap Quadrupole - orbitrap MS/MS, to identify the significant differentially expressed proteins (DEPs). Bioinformatics analyses, including Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway annotation and upstream regulatory analysis, were then performed on these retina proteins. Finally, a Western blotting experiment was carried out to verify the difference in the abundance of transcript factor E2F1. In this study, we identified a total of 2375 protein groups from the retinal protein samples of RCS rats and non-dystrophic congenic controls. Four hundred thirty-four significantly DEPs were selected by Student's t -test. Based on the results of the bioinformatics analysis, we identified mitochondrial dysfunction and transcription factor E2F1 as the key initiation factors in early retinal degenerative process. We showed that the mitochondrial dysfunction and the transcription factor E2F1 substantially contribute to the disease etiology of RP. The results provide a new potential therapeutic approach for this retinal degenerative disease.

Proteomic profiling of early degenerative retina of RCS rats

Directory of Open Access Journals (Sweden)

Zhi-Hong Zhu

2017-06-01

Full Text Available AIM: To identify the underlying cellular and molecular changes in retinitis pigmentosa (RP. METHODS: Label-free quantification-based proteomics analysis, with its advantages of being more economic and consisting of simpler procedures, has been used with increasing frequency in modern biological research. Dystrophic RCS rats, the first laboratory animal model for the study of RP, possess a similar pathological course as human beings with the diseases. Thus, we employed a comparative proteomics analysis approach for in-depth proteome profiling of retinas from dystrophic RCS rats and non-dystrophic congenic controls through Linear Trap Quadrupole - orbitrap MS/MS, to identify the significant differentially expressed proteins (DEPs. Bioinformatics analyses, including Gene ontology (GO and Kyoto Encyclopedia of Genes and Genomes (KEGG pathway annotation and upstream regulatory analysis, were then performed on these retina proteins. Finally, a Western blotting experiment was carried out to verify the difference in the abundance of transcript factor E2F1. RESULTS: In this study, we identified a total of 2375 protein groups from the retinal protein samples of RCS rats and non-dystrophic congenic controls. Four hundred thirty-four significantly DEPs were selected by Student’s t-test. Based on the results of the bioinformatics analysis, we identified mitochondrial dysfunction and transcription factor E2F1 as the key initiation factors in early retinal degenerative process. CONCLUSION: We showed that the mitochondrial dysfunction and the transcription factor E2F1 substantially contribute to the disease etiology of RP. The results provide a new potential therapeutic approach for this retinal degenerative disease.

Experimental Results and Numerical Simulation of the Target RCS using Gaussian Beam Summation Method

Directory of Open Access Journals (Sweden)

Ghanmi Helmi

2018-05-01

Full Text Available This paper presents a numerical and experimental study of Radar Cross Section (RCS of radar targets using Gaussian Beam Summation (GBS method. The purpose GBS method has several advantages over ray method, mainly on the caustic problem. To evaluate the performance of the chosen method, we started the analysis of the RCS using Gaussian Beam Summation (GBS and Gaussian Beam Launching (GBL, the asymptotic models Physical Optic (PO, Geometrical Theory of Diffraction (GTD and the rigorous Method of Moment (MoM. Then, we showed the experimental validation of the numerical results using experimental measurements which have been executed in the anechoic chamber of Lab-STICC at ENSTA Bretagne. The numerical and experimental results of the RCS are studied and given as a function of various parameters: polarization type, target size, Gaussian beams number and Gaussian beams width.

ESTIMATION OF WIDE BAND RADAR CROSS SECTION (RCS OF REGULAR SHAPED OBJECTS USING METHOD OF MOMENTS (MOM

Directory of Open Access Journals (Sweden)

M. Madheswaran

2012-06-01

Full Text Available Modern fighter aircrafts, ships, missiles etc need to be very low Radar Cross Section (RCS designs, to avoid detection by hostile radars. Hence accurate prediction of RCS of complex objects like aircrafts is essential to meet this requirement. A simple and efficient numerical procedure for treating problems of wide band RCS prediction Perfect Electric Conductor (PEC objects is developed using Method of Moment (MoM. Implementation of MoM for prediction of RCS involves solving Electric Field Integral Equation (EFIE for electric current using the vector and scalar potential solutions, which satisfy the boundary condition that the tangential electric field at the boundary of the PEC body is zero. For numerical purposes, the objects are modeled using planar triangular surfaces patches. Set of special sub-domain type basis functions are defined on pairs of adjacent triangular patches. These basis functions yield a current representation free of line or point charges at sub-domain boundaries. Once the current distribution is obtained, dipole model is used to find Scattering field in free space. RCS can be calculated from the scattered and incident fields. Numerical results for a square plate, a cube, and a sphere are presented over a bandwidth.

Non-Toxic Orbiter Maneuvering System (OMS) and Reaction Control System

Science.gov (United States)

Hurlbert, Eric A.; Nicholson, Leonard S. (Technical Monitor)

1999-01-01

NASA is pursuing the technology and advanced development of a non-toxic (NT) orbital maneuvering system (OMS) and reaction control system (RCS) for shuttle upgrades, RLV, and reusable first stages. The primary objectives of the shuttle upgrades program are improved safety, improved reliability, reduced operations time and cost, improved performance or capabilities, and commonality with future space exploration needs. Non-Toxic OMS/RCS offers advantages in each of these categories. A non-toxic OMS/RCS eliminates the ground hazards and the flight safety hazards of the toxic and corrosive propellants. The cost savings for ground operations are over $24M per year for 7 flights, and the savings increase with increasing flight rate up to $44M per year. The OMS/RCS serial processing time is reduced from 65 days to 13 days. The payload capability can be increased up to 5100 Ibms. The non-toxic OMS/RCS also provides improved space station reboost capability up to 20 nautical miles over the current toxic system of 14 nautical miles. A NT OMS/RCS represents a clear advancement in the SOA over MMH/NTO. Liquid oxygen and ethanol are clean burning, high-density propellants that provide a high degree of commonality with other spacecraft subsystems including life support, power, and thermal control, and with future human exploration and development of space missions. The simple and reliable pressure-fed design uses sub-cooled liquid oxygen at 250 to 350 psia, which allows a propellant to remain cryogenic for longer periods of time. The key technologies are thermal insulation and conditioning techniques are used to maintain the sub-cooling. Phase I successfully defined the system architecture, designed an integrated OMS/RCS propellant tank, analyzed the feed system, built and tested the 870 lbf RCS thrusters, and tested the 6000 lbf OMS engine. Phase 11 is currently being planned for the development and test of full-scale prototype of the system in 1999 and 2000

Seabrook simulator model upgrade: Implementation and validation of two-phase, nonequilibrium RCS and steam generator models

International Nuclear Information System (INIS)

Kao, S.

1990-01-01

A number of deficiencies in the original RCS and steam generator models on the Seabrook simulator were found to give unrealistic results under some off-normal and accident conditions. These deficiencies are attributed to the simplistic assumptions used in the original models, such as the homogeneous, equilibrium equations used in the pressurizer and steam generator models, and the single-phase flow model used in the RCS thermal-hydraulic model. To improve the fidelity of the simulator, efforts have been made to upgrade the RCS and steam generator models to include two-phase, nonequilibrium features. In the new RCS model, the following major assumptions are used to derive the finite difference form of the conservation equations: a donor-cell differencing scheme is adopted to allow flow reversal; a single pressure is used to evaluate properties; a single mass flow rate is assumed in each loop; enthalpy is assumed to vary linearly within each control volume; a homogeneous flow is assumed under two-phase conditions. The pressurizer is divided into a vapor region and a liquid region, each of which is represented by a set of mass and energy conservation equations. Interfacial mass and energy exchange mechanisms (condensation and flashing), thermal interactions between the vessel and fluids, and thermal nonequilibrium between the phases are included in the pressurizer model. The steam generator is divided into the vapor dome, riser, and downcomer regions. The assumptions applied are similar to those of the RCS and pressurizer models. A momentum model is incorporated to calculate the recirculation flow and simulate the downcomer level shrink/swell phenomenon. The new RCS and steam generator models are validated by comparing the simulator calculations against sister plant data and FSAR vendor analysis. The results show the new models give realistic and reliable calculations under off-normal and accident conditions

Verification of the CADRCS RCS tool for NCTR work

CSIR Research Space (South Africa)

Botha, L

2007-03-01

Full Text Available This paper looks at the suitability of using the CADRCS RCS prediction tool for research into a class of NCTR work where the radar will give a high resolution output of the target, either a High Range Resolution (HRR) plot or Inverse Synthetic...

Photosynthetic antennas and reaction centers: Current understanding and prospects for improvement

Energy Technology Data Exchange (ETDEWEB)

Blankenship, R.E. [Arizona State Univ., Tempe, AZ (United States)

1996-09-01

A brief introduction to the principles, structures and kinetic processes that take place in natural photosynthetic reaction center complexes is presented. Energy is first collected by an antenna system, and is transferred to a reaction center complex where primary electron transfer takes place. Secondary reactions lead to oxidation of water and reduction of CO{sub 2} in some classes of organisms. Antenna systems are highly regulated to maximize energy collection efficiency while avoiding photodamage. Some areas that are presently not well understood are listed.

An investigation of the RCS (radar cross section) computation of grid cavities

International Nuclear Information System (INIS)

Sabihi, Ahmad

2014-01-01

In this paper, the aperture of a cavity is covered by a metallic grid net. This metallic grid is to reduce RCS deduced by impinging radar ray on the aperture. A radar ray incident on a grid net installed on a cavity may create six types of propagation. 1-Incident rays entering inside the cavity and backscattered from it.2-Incidebnt rays on the grid net and created reection rays as an array of scatterers. These rays may create a wave with phase difference of 180 degree with respect to the exiting rays from the cavity.3-Incident rays on the grid net create surface currents owing on the net and make travelling waves, which regenerate the magnetic and electric fields. These fields make again propagated waves against incident ones.4-Creeping waves.5-Diffracted rays due to leading edges of net’s elements.6-Mutual impedance among elements of the net could be effective on the resultant RCS. Therefore, the author compares the effects of three out of six properties to a cavity without grid net. This comparison shows that RCS prediction of cavity having a grid net is much more reduced than that of without one

An investigation of the RCS (radar cross section) computation of grid cavities

Energy Technology Data Exchange (ETDEWEB)

Sabihi, Ahmad [Department of Mathematical Sciences, Sharif University of Technology, Tehran (Iran, Islamic Republic of)

2014-12-10

In this paper, the aperture of a cavity is covered by a metallic grid net. This metallic grid is to reduce RCS deduced by impinging radar ray on the aperture. A radar ray incident on a grid net installed on a cavity may create six types of propagation. 1-Incident rays entering inside the cavity and backscattered from it.2-Incidebnt rays on the grid net and created reection rays as an array of scatterers. These rays may create a wave with phase difference of 180 degree with respect to the exiting rays from the cavity.3-Incident rays on the grid net create surface currents owing on the net and make travelling waves, which regenerate the magnetic and electric fields. These fields make again propagated waves against incident ones.4-Creeping waves.5-Diffracted rays due to leading edges of net’s elements.6-Mutual impedance among elements of the net could be effective on the resultant RCS. Therefore, the author compares the effects of three out of six properties to a cavity without grid net. This comparison shows that RCS prediction of cavity having a grid net is much more reduced than that of without one.

Design and Stability of an On-Orbit Attitude Control System Using Reaction Control Thrusters

Science.gov (United States)

Hall, Robert A.; Hough, Steven; Orphee, Carolina; Clements, Keith

2016-01-01

Basic principles for the design and stability of a spacecraft on-orbit attitude control system employing on-off Reaction Control System (RCS) thrusters are presented. Both vehicle dynamics and the control system actuators are inherently nonlinear, hence traditional linear control system design approaches are not directly applicable. This paper has two main aspects: It summarizes key RCS design principles from earlier NASA vehicles, notably the Space Shuttle and Space Station programs, and introduces advances in the linear modelling and analyses of a phase plane control system derived in the initial development of the NASA's next upper stage vehicle, the Exploration Upper Stage (EUS). Topics include thruster hardware specifications, phase plane design and stability, jet selection approaches, filter design metrics, and RCS rotational maneuver logic.

Thermodynamic Vent System for an On-Orbit Cryogenic Reaction Control Engine

Science.gov (United States)

Hurlbert, Eric A.; Romig, Kris A.; Jimenez, Rafael; Flores, Sam

2012-01-01

A report discusses a cryogenic reaction control system (RCS) that integrates a Joule-Thompson (JT) device (expansion valve) and thermodynamic vent system (TVS) with a cryogenic distribution system to allow fine control of the propellant quality (subcooled liquid) during operation of the device. It enables zero-venting when coupled with an RCS engine. The proper attachment locations and sizing of the orifice are required with the propellant distribution line to facilitate line conditioning. During operations, system instrumentation was strategically installed along the distribution/TVS line assembly, and temperature control bands were identified. A sub-scale run tank, full-scale distribution line, open-loop TVS, and a combination of procured and custom-fabricated cryogenic components were used in the cryogenic RCS build-up. Simulated on-orbit activation and thruster firing profiles were performed to quantify system heat gain and evaluate the TVS s capability to maintain the required propellant conditions at the inlet to the engine valves. Test data determined that a small control valve, such as a piezoelectric, is optimal to provide continuously the required thermal control. The data obtained from testing has also assisted with the development of fluid and thermal models of an RCS to refine integrated cryogenic propulsion system designs. This system allows a liquid oxygenbased main propulsion and reaction control system for a spacecraft, which improves performance, safety, and cost over conventional hypergolic systems due to higher performance, use of nontoxic propellants, potential for integration with life support and power subsystems, and compatibility with in-situ produced propellants.

Alterations in NMDA receptor expression during retinal degeneration in the RCS rat.

Science.gov (United States)

Gründer, T; Kohler, K; Guenther, E

2001-01-01

To determine how a progressive loss of photoreceptor cells and the concomitant loss of glutamatergic input to second-order neurons can affect inner-retinal signaling, glutamate receptor expression was analyzed in the Royal College of Surgeons (RCS) rat, an animal model of retinitis pigmentosa. Immunohistochemistry was performed on retinal sections of RCS rats and congenic controls between postnatal (P) day 3 and the aged adult (up to P350) using specific antibodies against N-methyl-D-aspartate (NMDA) subunits. All NMDA subunits (NR1, NR2A-2D) were expressed in control and dystrophic retinas at all ages, and distinct patterns of labeling were found in horizontal cells, subpopulations of amacrine cells and ganglion cells, as well as in the outer and inner plexiform layer (IPL). NRI immunoreactivity in the inner plexiform layer of adult control retinas was concentrated in two distinct bands, indicating a synaptic localization of NMDA receptors in the OFF and ON signal pathways. In the RCS retina, these bands of NRI immunoreactivity in the IPL were much weaker in animals older than P40. In parallel, NR2B immunoreactivity in the outer plexiform layer (OPL) of RCS rats was always reduced compared to controls and vanished between P40 and P120. The most striking alteration observed in the degenerating retina, however, was a strong expression of NRI immunoreactivity in Müller cell processes in the inner retina which was not observed in control animals and which was present prior to any visible sign of photoreceptor degeneration. The results suggest functional changes in glutamatergic receptor signaling in the dystrophic retina and a possible involvement of Müller cells in early processes of this disease.

Site Energies of Active and Inactive Pheophytins in the Reaction Center of Photosystem II from Chlamydomonas Reinhardtii

Energy Technology Data Exchange (ETDEWEB)

Acharya, K.; Neupane, B.; Zazubovich, V.; Sayre, R. T.; Picorel, R.; Seibert, M.; Jankowiak, R.

2012-03-29

It is widely accepted that the primary electron acceptor in various Photosystem II (PSII) reaction center (RC) preparations is pheophytin {alpha} (Pheo {alpha}) within the D1 protein (Pheo{sub D1}), while Pheo{sub D2} (within the D2 protein) is photochemically inactive. The Pheo site energies, however, have remained elusive, due to inherent spectral congestion. While most researchers over the past two decades placed the Q{sub y}-states of Pheo{sub D1} and Pheo{sub D2} bands near 678-684 and 668-672 nm, respectively, recent modeling [Raszewski et al. Biophys. J. 2005, 88, 986-998; Cox et al. J. Phys. Chem. B 2009, 113, 12364-12374] of the electronic structure of the PSII RC reversed the assignment of the active and inactive Pheos, suggesting that the mean site energy of Pheo{sub D1} is near 672 nm, whereas Pheo{sub D2} ({approx}677.5 nm) and Chl{sub D1} ({approx}680 nm) have the lowest energies (i.e., the Pheo{sub D2}-dominated exciton is the lowest excited state). In contrast, chemical pigment exchange experiments on isolated RCs suggested that both pheophytins have their Q{sub y} absorption maxima at 676-680 nm [Germano et al. Biochemistry 2001, 40, 11472-11482; Germano et al. Biophys. J. 2004, 86, 1664-1672]. To provide more insight into the site energies of both Pheo{sub D1} and Pheo{sub D2} (including the corresponding Q{sub x} transitions, which are often claimed to be degenerate at 543 nm) and to attest that the above two assignments are most likely incorrect, we studied a large number of isolated RC preparations from spinach and wild-type Chlamydomonas reinhardtii (at different levels of intactness) as well as the Chlamydomonas reinhardtii mutant (D2-L209H), in which the active branch Pheo{sub D1} is genetically replaced with chlorophyll {alpha} (Chl {alpha}). We show that the Q{sub x}-/Q{sub y}-region site energies of Pheo{sub D1} and Pheo{sub D2} are {approx}545/680 nm and {approx}541.5/670 nm, respectively, in good agreement with our previous assignment

Quantum measurement corrections to CIDNP in photosynthetic reaction centers

International Nuclear Information System (INIS)

Kominis, Iannis K

2013-01-01

Chemically induced dynamic nuclear polarization is a signature of spin order appearing in many photosynthetic reaction centers. Such polarization, significantly enhanced above thermal equilibrium, is known to result from the nuclear spin sorting inherent in the radical pair mechanism underlying long-lived charge-separated states in photosynthetic reaction centers. We will show here that the recently understood fundamental quantum dynamics of radical-ion-pair reactions open up a new and completely unexpected pathway toward obtaining chemically induced dynamic nuclear polarization signals. The fundamental decoherence mechanism inherent in the recombination process of radical pairs is shown to produce nuclear spin polarizations of the order of 10 4 times (or more) higher than the thermal equilibrium value at the Earth's magnetic field relevant to natural photosynthesis. This opens up the possibility of a fundamentally new exploration of the biological significance of high nuclear polarizations in photosynthesis. (paper)

Classical and modern power spectrum estimation for tune measurement in CSNS RCS

International Nuclear Information System (INIS)

Yang Xiaoyu; Xu Taoguang; Fu Shinian; Zeng Lei; Bian Xiaojuan

2013-01-01

Precise measurement of betatron tune is required for good operating condition of CSNS RCS. The fractional part of betatron tune is important and it can be measured by analyzing the signals of beam position from the appointed BPM. Usually these signals are contaminated during the acquisition process, therefore several power spectrum methods are used to improve the frequency resolution. In this article classical and modern power spectrum methods are used. In order to compare their performance, the results of simulation data and IQT data from J-PARC RCS are discussed. It is shown that modern power spectrum estimation has better performance than the classical ones, though the calculation is more complex. (authors)

Reactions of carbon radicals generated by 1,5-transposition of reactive centers

Directory of Open Access Journals (Sweden)

ZIVORAD CEKOVIC

2005-03-01

Full Text Available Radical intermediates can undergo specific reactions, such as intramolecular rearrangements, i.e., the transpositions of radical centers, which are not known in classical ionic organic reactions. 1,5-Transposition of a radical center to a non-activated carbon atom are of great synthetic importance. It can be successfully applied for the introduction of different functional groups (oxygen, nitrogen, sulfur, halogens onto a carbon atom remote from the present functional group. In addition to functionalization of a remote non-activated carbon atom, the formation of new C-C bonds on the d-carbon atom have also been achieved. 1,5-Transposition of the radical centers takes place from alkoxyl, aminyl and carbon radicals to a remote carbon atom. Relocation of the radical centers preferentially involves 1,5-transfer of a hydrogen atom, although migrations of some other groups are known. The reactions of the carbon radical generated by 1,5-relocation of the radical center are presented and their synthetic applications are reviewed.

Uneven-Layered Coding Metamaterial Tile for Ultra-wideband RCS Reduction and Diffuse Scattering.

Science.gov (United States)

Su, Jianxun; He, Huan; Li, Zengrui; Yang, Yaoqing Lamar; Yin, Hongcheng; Wang, Junhong

2018-05-25

In this paper, a novel uneven-layered coding metamaterial tile is proposed for ultra-wideband radar cross section (RCS) reduction and diffuse scattering. The metamaterial tile is composed of two kinds of square ring unit cells with different layer thickness. The reflection phase difference of 180° (±37°) between two unit cells covers an ultra-wide frequency range. Due to the phase cancellation between two unit cells, the metamaterial tile has the scattering pattern of four strong lobes deviating from normal direction. The metamaterial tile and its 90-degree rotation can be encoded as the '0' and '1' elements to cover an object, and diffuse scattering pattern can be realized by optimizing phase distribution, leading to reductions of the monostatic and bi-static RCSs simultaneously. The metamaterial tile can achieve -10 dB RCS reduction from 6.2 GHz to 25.7 GHz with the ratio bandwidth of 4.15:1 at normal incidence. The measured and simulated results are in good agreement and validate the proposed uneven-layered coding metamaterial tile can greatly expanding the bandwidth for RCS reduction and diffuse scattering.

Intraocular gene transfer of ciliary neurotrophic factor rescues photoreceptor degeneration in RCS rats.

Science.gov (United States)

Huang, Shun-Ping; Lin, Po-Kang; Liu, Jorn-Hon; Khor, Chin-Ni; Lee, Yih-Jing

2004-01-01

Ciliary neurotrophic factor (CNTF) is known as an important factor in the regulation of retinal cell growth. We used both recombinant CNTF and an adenovirus carrying the CNTF gene to regulate retinal photoreceptor expression in a retinal degenerative animal, Royal College of Surgeons (RCS) rats. Cells in the outer nuclear layer of the retinae from recombinant-CNTF-treated, adenoviral-CNTF-treated, saline-operated, and contralateral untreated preparations were examined for those exhibiting CNTF photoreceptor protective effects. Cell apoptosis in the outer nuclear layer of the retinae was also detected. It was found that CNTF had a potent effect on delaying the photoreceptor degeneration process in RCS rats. Furthermore, adenovirus CNTF gene transfer was proven to be better at rescuing photoreceptors than that when using recombinant CNTF, since adenoviral CNTF prolonged the photoreceptor protection effect. The function of the photoreceptors was also examined by taking electroretinograms of different animals. Adenoviral-CNTF-treated eyes showed better retinal function than did the contralateral control eyes. This study indicates that adenoviral CNTF effectively rescues degenerating photoreceptors in RCS rats. Copyright 2004 National Science Council, ROC and S. Karger AG, Basel

Elucidating the design principles of photosynthetic electron-transfer proteins by site-directed spin labeling EPR spectroscopy.

Science.gov (United States)

Ishara Silva, K; Jagannathan, Bharat; Golbeck, John H; Lakshmi, K V

2016-05-01

Site-directed spin labeling electron paramagnetic resonance (SDSL EPR) spectroscopy is a powerful tool to determine solvent accessibility, side-chain dynamics, and inter-spin distances at specific sites in biological macromolecules. This information provides important insights into the structure and dynamics of both natural and designed proteins and protein complexes. Here, we discuss the application of SDSL EPR spectroscopy in probing the charge-transfer cofactors in photosynthetic reaction centers (RC) such as photosystem I (PSI) and the bacterial reaction center (bRC). Photosynthetic RCs are large multi-subunit proteins (molecular weight≥300 kDa) that perform light-driven charge transfer reactions in photosynthesis. These reactions are carried out by cofactors that are paramagnetic in one of their oxidation states. This renders the RCs unsuitable for conventional nuclear magnetic resonance spectroscopy investigations. However, the presence of native paramagnetic centers and the ability to covalently attach site-directed spin labels in RCs makes them ideally suited for the application of SDSL EPR spectroscopy. The paramagnetic centers serve as probes of conformational changes, dynamics of subunit assembly, and the relative motion of cofactors and peptide subunits. In this review, we describe novel applications of SDSL EPR spectroscopy for elucidating the effects of local structure and dynamics on the electron-transfer cofactors of photosynthetic RCs. Because SDSL EPR Spectroscopy is uniquely suited to provide dynamic information on protein motion, it is a particularly useful method in the engineering and analysis of designed electron transfer proteins and protein networks. This article is part of a Special Issue entitled Biodesign for Bioenergetics--the design and engineering of electronic transfer cofactors, proteins and protein networks, edited by Ronald L. Koder and J.L. Ross Anderson. Copyright © 2016. Published by Elsevier B.V.

Differences in the use of spirometry between rural and urban primary care centers in Spain

Directory of Open Access Journals (Sweden)

Márquez-Martín E

2015-08-01

Full Text Available Eduardo Márquez-Martín,1 Joan B Soriano,2 Myriam Calle Rubio,3 Jose Luis Lopez-Campos1,4 On behalf of the 3E project 1Unidad Médico-Quirúrgica de Enfermedades Respiratorias, Instituto de Biomedicina de Sevilla (IBiS, Hospital Universitario Virgen del Rocío, Universidad de Sevilla, Sevilla, 2Instituto de Investigación Hospital Universitario de la Princesa (IISP, Universidad Autónoma de Madrid, Cátedra UAM-Linde, 3Servicio de Neumología, Hospital Universitario Clínico San Carlos, 4Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES, Instituto de Salud Carlos III, Madrid, Spain Objectives: The aim of this study is to evaluate the ability and practice of spirometry, training of technicians, and spirometry features in primary care centers in Spain, evaluating those located in a rural environment against those in urban areas.Methods: An observational cross-sectional study was conducted in 2012 by a telephone survey in 970 primary health care centers in Spain. The centers were divided into rural or urban depending on the catchment population. The survey contacted technicians in charge of spirometry and consisted of 36 questions related to the test that included the following topics: center resources, training doctors and technicians, using the spirometer, bronchodilator test, and the availability of spirometry and maintenance.Results: Although the sample size was achieved in both settings, rural centers (RCs gave a lower response rate than urban centers (UCs. The number of centers without spirometry in rural areas doubled those in the urban areas. Most centers had between one and two spirometers. However, the number of spirometry tests per week was significantly lower in RCs than in UCs (4 [4.1%] vs 6.9 [5.7%], P<0.01. The availability of a specific schedule for conducting spirometries was higher in RCs than in UCs (209 [73.0%] vs 207 [64.2%], P=0.003. RCs were more satisfied with the spirometries (7.8 vs 7.6, P

Design and Implementation of Adaptive Turbo Encoder for Quantized Software Defined Low-Power DVB-RCS Radios

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S. H. Elramly

2010-11-01

Full Text Available Turbo codes are employed in every robust wireless digital communications system. Those codes have been adopted for the satellite return channel in DVB-RCS (Return Channel via Satellite standard. In Software Defined Radios (SDRs, Field Programmable Gate Array technology (FPGA is considered a highly configurable option for implementing many sophisticated signal processing tasks. The implementation for such codes is complex and dissipates a large amount of power. This paper studies the efficient implementation of quantized DVB-RCS turbo coding. Also, a low-power, turbo encoder for DVB-RCS is described using a VHDL code. The proposed encoder design is implemented on Xilinx Virtex-II Pro, XC2vpx30 FPGA chip. FPGA Advantage Pro package provided by Mentor Graphics is used for VHDL description and ISE 10.1 by Xilinx is used for synthetization.

The Type 1 Homodimeric Reaction Center in Heliobacterium modesticaldum

Energy Technology Data Exchange (ETDEWEB)

Golbeck, John [Pennsylvania State Univ., University Park, PA (United States)

2018-01-15

In this funding period, we (i) found that strong illumination of Heliobacterium modesticaldum cells results in saturation of the electron acceptor pool, leading to reduction of the acceptor side and the creation of a back-reacting state that gives rise to delayed fluorescence; (ii) noted that when the FX cluster is reduced in purified reaction centers, no electron transfer occurs beyond A0, even though a quinone is present; (iii) observed by photochemically induced dynamic nuclear polarization (photo-CIDNP) studies of whole cells of Heliobacterium mobilis that primary charge separation is retained even after conversion of the majority of BChl g to Chl aF. ; and (iv) purified a homogeneous preparation of reaction center cores, which led to promising crystallization trials to obtain a three-dimensional structure.

Numerical simulation of RCS for carrier electronic warfare airplanes

Directory of Open Access Journals (Sweden)

Yue Kuizhi

2015-04-01

Full Text Available This paper studies the radar cross section (RCS of carrier electronic warfare airplanes. Under the typical naval operations section, the mathematical model of the radar wave’s pitch angle incidence range analysis is established. Based on the CATIA software, considering dynamic deflections of duck wing leading edge flaps, flaperons, horizontal tail, and rudder, as well as aircraft with air-to-air missile, anti-radiation missile, electronic jamming pod, and other weapons, the 3D models of carrier electronic warfare airplanes Model A and Model B with weapons were established. Based on the physical optics method and the equivalent electromagnetic flow method, by the use of the RCSAnsys software, the characteristics of carrier electronic warfare airplanes’ RCS under steady and dynamic flights were simulated under the UHF, X, and S radar bands. This paper researches the detection probability of aircraft by radars under the condition of electronic warfare, and completes the mathematical statistical analysis of the simulation results. The results show that: The Model A of carrier electronic warfare airplane is better than Model B on stealth performance and on discover probability by radar detection effectively.

Chemical Characterization and Reactivity Testing of Fuel-Oxidizer Reaction Product (Test Report)

Science.gov (United States)

1996-01-01

The product of incomplete reaction of monomethylhydrazine (MMH) and nitrogen tetroxide (NTO) propellants, or fuel-oxidizer reaction product (FORP), has been hypothesized as a contributory cause of an anomaly which occurred in the chamber pressure (PC) transducer tube on the Reaction Control Subsystem (RCS) aft thruster 467 on flight STS-51. A small hole was found in the titanium-alloy PC tube at the first bend below the pressure transducer. It was surmised that the hole may have been caused by heat and pressure resulting from ignition of FORP. The NASA Johnson Space Center (JSC) White Sands Test Facility (WSTF) was requested to define the chemical characteristics of FORP, characterize its reactivity, and simulate the events in a controlled environment which may have lead to the Pc-tube failure. Samples of FORP were obtained from the gas-phase reaction of MMH with NTO under laboratory conditions, the pulsed firings of RCS thrusters with modified PC tubes using varied oxidizer or fuel lead times, and the nominal RCS thruster firings at WSTF and Kaiser-Marquardt. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), accelerating rate calorimetry (ARC), ion chromatography (IC), inductively coupled plasma (ICP) spectrometry, thermogravimetric analysis (TGA) coupled to FTIR (TGA/FTIR), and mechanical impact testing were used to qualitatively and quantitatively characterize the chemical, thermal, and ignition properties of FORP. These studies showed that the composition of FORP is variable but falls within a limited range of compositions that depends on the fuel loxidizer ratio at the time of formation, composition of the post-formation atmosphere (reducing or oxidizing), and reaction or postreaction temperature. A typical composition contains methylhydrazinium nitrate (MMHN), ammonium nitrate (AN), methylammonium nitrate (MAN), and trace amounts of hydrazinium nitrate and 1,1-dimethylhydrazinium nitrate. The thermal decomposition

Fuzzy-4D/RCS for Unmanned Aerial Vehicles

OpenAIRE

Olivares Mendez, Miguel Angel; Campoy, Pascual; Mondragon, Ivan F.; Martinez, Carol

2010-01-01

Abstract This paper presents an improvement of the cognitive architecture, 4D/RCS, developed by the NIST. This improvement consist of the insertion of Fuzzy Logic cells (FLCs), in different parts and hierarchy levels of the architecture, and the adaptation of this architecture for Unmanned Aerial Vehicles (UAVs). This advance provides an improvement in the functionality of the system based on the uses of the Miguel Olivares’ Fuzzy Software for the definition of the FLCs and its...

Observations of electrons in the Intense Pulse Neutron Source (IPNS) Rapid Cycling Synchrotron (RCS)

International Nuclear Information System (INIS)

Dooling, J.C.; Brumwell, F.R.; Czyz, W.S.; Harkay, K.C.; Lien, M.K.; McMichael, G.E.

2004-01-01

In the process of accelerating protons from 50 to 450 MeV at 30 Hz, low-energy electrons are generated within the IPNS RCS vacuum chamber. Electrons from background gas stripping are detected using an Ionization Profile Monitor (IPM) to generate integrated, horizontal charge distributions of the single-harmonic bunch during acceleration. Recently, a Retarding Field Analyzer (RFA) was installed in the RCS to look for evidence of beam-induced multipacting by measuring the electrons ejected by the space charge of the beam. A wide-band, high-gain transimpedance amplifier has been built to observe time structure in the electron signal detected with the RFA. Though a noisy power supply prevented full I-V characteristics from being obtained, interesting features are observed; especially, after the period of phase modulation between the rf cavities that is deliberately introduced during the cycle. The phase modulation generates a longitudinal quadrupole oscillation in the bunch, which is believed to enhance beam stability. Preliminary results indicate that electron multipacting is not significant in the RCS. The effects of background gas neutralization are considered and details of the RFA measurements are presented.

Polarized e-bunch acceleration at Cornell RCS: Tentative tracking simulations

Energy Technology Data Exchange (ETDEWEB)

Meot, F. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ptitsyn, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ranjbar, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Rubin, D. [Brookhaven National Lab. (BNL), Upton, NY (United States)

2017-10-19

An option as an injector into eRHIC electron storage ring is a rapid-cyclic synchrotron (RCS). Rapid acceleration of polarized electron bunches has never been done, Cornell synchrotron might lend itself to dedicated tests, which is to be first explored based on numerical investigations. This paper is a very preliminary introduction to the topic.

RCS Leak Rate Calculation with High Order Least Squares Method

International Nuclear Information System (INIS)

Lee, Jeong Hun; Kang, Young Kyu; Kim, Yang Ki

2010-01-01

As a part of action items for Application of Leak before Break(LBB), RCS Leak Rate Calculation Program is upgraded in Kori unit 3 and 4. For real time monitoring of operators, periodic calculation is needed and corresponding noise reduction scheme is used. This kind of study was issued in Korea, so there have upgraded and used real time RCS Leak Rate Calculation Program in UCN unit 3 and 4 and YGN unit 1 and 2. For reduction of the noise in signals, Linear Regression Method was used in those programs. Linear Regression Method is powerful method for noise reduction. But the system is not static with some alternative flow paths and this makes mixed trend patterns of input signal values. In this condition, the trend of signal and average of Linear Regression are not entirely same pattern. In this study, high order Least squares Method is used to follow the trend of signal and the order of calculation is rearranged. The result of calculation makes reasonable trend and the procedure is physically consistence

Investigation of 3-D RCS Image formation of ships using ISAR

CSIR Research Space (South Africa)

Lord, RT

2006-05-01

Full Text Available Conventional Inverse Synthetic Aperture Radar (ISAR) utilises the rotational motion of a target such as a ship or an aircraft to obtain a 2-D image of the target’s radar cross section (RCS) profile from a coherent radar system. This concept can...

A microRNA, mir133b, suppresses melanopsin expression mediated by failure dopaminergic amacrine cells in RCS rats.

Science.gov (United States)

Li, Yaochen; Li, Chunshi; Chen, Zhongshan; He, Jianrong; Tao, Zui; Yin, Zheng Qin

2012-03-01

The photopigment melanopsin and melanopsin-containing RGCs (mRGCs or ipRGCs) represent a brand-new and exciting direction in the field of visual field. Although the melanopsin is much less sensitive to light and has far less spatial resolution, mRGCs have the unique ability to project to brain areas by the retinohypothalamic tract (RHT) and communicate directly with the brain. Unfortunately, melanopsin presents lower expression levels in many acute and chronic retinal diseases. The molecular mechanisms underlying melanopsin expression are not yet really understood. MicroRNAs play important roles in the control of development. Most importantly, the link of microRNA biology to a diverse set of cellular processes, ranging from proliferation, apoptosis and malignant transformation to neuronal development and fate specification is emerging. We employed Royal College of Surgeon (RCS) rats as animal model to investigate the underlying molecular mechanism regulating melanopsin expression using a panel of miRNA by quantitative real-time reverse transcription polymerase chain reaction. We identified a microRNA, mir133b, that is specifically expressed in retinal dopaminergic amacrine cells as well as markedly increased expression at early stage during retinal degeneration in RCS rats. The overexpression of mir133b downregulates the important transcription factor Pitx3 expression in dopaminergic amacrine cells in RCS rats retinas and makes amacrine cells stratification deficit in IPL. Furthermore, deficient dopaminergic amacrine cells presented decreased TH expression and dopamine production, which lead to a failure to direct mRGCs dendrite to stratify and enter INL and lead to the reduced correct connections between amacrine cells and mRGCs. Our study suggested that overexpression of mir133b and downregulated Pitx3 suppress maturation and function of dopaminergic amacrine cells, and overexpression of mir133b decreased TH and D2 receptor expression as well as dopamine

The unusually strong hydrogen bond between the carbonyl of Q(A) and His M219 in the Rhodobacter sphaeroides reaction center is not essential for efficient electron transfer from Q(A)(-) to Q(B).

Science.gov (United States)

Breton, Jacques; Lavergne, Jérôme; Wakeham, Marion C; Nabedryk, Eliane; Jones, Michael R

2007-06-05

In native reaction centers (RCs) from photosynthetic purple bacteria the primary quinone (QA) and the secondary quinone (QB) are interconnected via a specific His-Fe-His bridge. In Rhodobacter sphaeroides RCs the C4=O carbonyl of QA forms a very strong hydrogen bond with the protonated Npi of His M219, and the Ntau of this residue is in turn coordinated to the non-heme iron atom. The second carbonyl of QA is engaged in a much weaker hydrogen bond with the backbone N-H of Ala M260. In previous work, a Trp side chain was introduced by site-directed mutagenesis at the M260 position in the RC of Rb. sphaeroides, resulting in a complex that is completely devoid of QA and therefore nonfunctional. A photochemically competent derivative of the AM260W mutant was isolated that contains a Cys side chain at the M260 position (denoted AM260(W-->C)). In the present work, the interactions between the carbonyl groups of QA and the protein in the AM260(W-->C) suppressor mutant have been characterized by light-induced FTIR difference spectroscopy of the photoreduction of QA. The QA-/QA difference spectrum demonstrates that the strong interaction between the C4=O carbonyl of QA and His M219 is lost in the mutant, and the coupled CO and CC modes of the QA- semiquinone are also strongly perturbed. In parallel, a band assigned to the perturbation of the C5-Ntau mode of His M219 upon QA- formation in the native RC is lacking in the spectrum of the mutant. Furthermore, a positive band between 2900 and 2400 cm-1 that is related to protons fluctuating within a network of highly polarizable hydrogen bonds in the native RC is reduced in amplitude in the mutant. On the other hand, the QB-/QB FTIR difference spectrum is essentially the same as for the native RC. The kinetics of electron transfer from QA- to QB were measured by the flash-induced absorption changes at 780 nm. Compared to native RCs the absorption transients are slowed by a factor of about 2 for both the slow phase (in the

Model photo reaction centers via genetic engineering

Energy Technology Data Exchange (ETDEWEB)

Zhiyu Wang; DiMagno, T.J.; Popov, M.; Norris, J.R. [Argonne National Lab., IL (United States)]|[Chicago Univ., IL (United States). Dept. of Chemistry; Chikin Chan; Fleming, G. [Chicago Univ., IL (United States). Dept. of Chemistry; Jau Tang; Hanson, D.; Schiffer, M. [Argonne National Lab., IL (United States)

1992-12-31

A series of reaction centers of Rhodococcus capsulatus isolated from a set of mutated organisms modified by site-directed mutagenesis at residues M208 and L181 are described. Changes in the amino acid at these sites affect both the energetics of the systems as well as the chemical kinetics for the initial ET event. Two empirical relations among the different mutants for the reduction potential and the ET rate are presented.

Model photo reaction centers via genetic engineering

Energy Technology Data Exchange (ETDEWEB)

Zhiyu Wang; DiMagno, T.J.; Popov, M.; Norris, J.R. (Argonne National Lab., IL (United States) Chicago Univ., IL (United States). Dept. of Chemistry); Chikin Chan; Fleming, G. (Chicago Univ., IL (United States). Dept. of Chemistry); Jau Tang; Hanson, D.; Schiffer, M. (Argonne National Lab., IL (United States))

1992-01-01

A series of reaction centers of Rhodococcus capsulatus isolated from a set of mutated organisms modified by site-directed mutagenesis at residues M208 and L181 are described. Changes in the amino acid at these sites affect both the energetics of the systems as well as the chemical kinetics for the initial ET event. Two empirical relations among the different mutants for the reduction potential and the ET rate are presented.

Characterization of the rcsA Gene from Pantoea sp. Strain PPE7 and Its Influence on Extracellular Polysaccharide Production and Virulence on Pleurotus eryngii

Directory of Open Access Journals (Sweden)

Min Keun Kim

2017-06-01

Full Text Available RcsA is a positive activator of extracellular polysaccharide (EPS synthesis in the Enterobacteriaceae. The rcsA gene of the soft rot pathogen Pantoea sp. strain PPE7 in Pleurotus eryngii was cloned by PCR amplification, and its role in EPS synthesis and virulence was investigated. The RcsA protein contains 3 highly conserved domains, and the C-terminal end of the open reading frame shared significant amino acid homology to the helix-turn-helix DNA binding motif of bacterial activator proteins. The inactivation of rcsA by insertional mutagenesis created mutants that had decreased production of EPS compared to the wild-type strain and abolished the virulence of Pantoea sp. strain PPE7 in P. eryngii. The Pantoea sp. strain PPE7 rcsA gene was shown to strongly affect the formation of the disease symptoms of a mushroom pathogen and to act as the virulence factor to cause soft rot disease in P. eryngii.

Preservation of photoreceptors in dystrophic RCS rats following allo- and xenotransplantation of IPE cells.

Science.gov (United States)

Thumann, Gabriele; Salz, Anna Katharina; Walter, Peter; Johnen, Sandra

2009-03-01

To examine whether iris pigment epithelial (IPE) cells transplanted into the subretinal space of Royal College of Surgeons (RCS) rats have the ability to rescue photoreceptors. Rat IPE (rIPE) or human IPE (hIPE) cells were transplanted subretinally in 23-day-old RCS rats. Sham injection and transplantation of ARPE-19 cells served as controls. After 12 weeks, eyes were evaluated for photoreceptor survival by morphometric analysis and electron microscopy. Morphometric analysis showed photoreceptor rescue in all transplanted and sham-injected animals (number of photoreceptors/300 microm retina+/-sd: rIPE 41.67 +/- 28; hIPE 29.50 +/- 16; ARPE-19 36.12 +/- 21; sham 16.56 +/- 6) compared to age-matched, control rats (number of photoreceptors/300 microm retina+/-sd: 9.71 +/- 4). Photoreceptor rescue was prominent in IPE cell-transplanted rats and was significantly greater than sham-injected eyes (p = 0.02 for rIPE and p = 0.04 for hIPE). Since IPE cells transplanted into the subretinal space have the ability to rescue photoreceptors from degeneration in the RCS rat without any harmful effects, IPE cells may represent an ideal cell to genetically modify and thus carry essential genetic information for the repair of defects in the subretinal space.

THYDE-P2 code: RCS (reactor-coolant system) analysis code

International Nuclear Information System (INIS)

Asahi, Yoshiro; Hirano, Masashi; Sato, Kazuo

1986-12-01

THYDE-P2, being characterized by the new thermal-hydraulic network model, is applicable to analysis of RCS behaviors in response to various disturbances including LB (large break)-LOCA(loss-of-coolant accident). In LB-LOCA analysis, THYDE-P2 is capable of through calculation from its initiation to complete reflooding of the core without an artificial change in the methods and models. The first half of the report is the description of the methods and models for use in the THYDE-P2 code, i.e., (1) the thermal-hydraulic network model, (2) the various RCS components models, (3) the heat sources in fuel, (4) the heat transfer correlations, (5) the mechanical behavior of clad and fuel, and (6) the steady state adjustment. The second half of the report is the user's mannual for the THYDE-P2 code (version SV04L08A) containing items; (1) the program control (2) the input requirements, (3) the execution of THYDE-P2 job, (4) the output specifications and (5) the sample problem to demonstrate capability of the thermal-hydraulic network model, among other things. (author)

Photosystem II and photoinhibition

NARCIS (Netherlands)

Feikema, Willem Onno

2006-01-01

Plants harvest light energy and convert it into chemical energy. Light absorption by photosystems I and II (PSI and PSII) results in charge separations in their reaction centers (RCs), initiating a chain of redox reactions with PSI generating the reducing power for CO2 assimilation into sugars, and

Resolution of issues related to alternative RCS injection in the absence of containment sump recirculation

International Nuclear Information System (INIS)

Charles L Kling; Stephen S Barshay; Mathew C Jacob; Michael J Friedman

2005-01-01

Full text of publication follows: On June 9, 2003 the US NRC issued Bulletin No. 2003-01 that deals with the potential impact of debris blockage on containment sump recirculation at PWRs during a Loss-of-Coolant Accident (LOCA). In response to the bulletin, the Omaha Public Power District (OPPD) is in the process of developing procedural and operational strategies for their Fort Calhoun Station (FCS) to address the issues raised. Westinghouse provided engineering support to OPPD in identifying and resolving issues related to alternative means of supplying safety injection water to the reactor coolant system (RCS) in the absence of containment sump recirculation. Nuclear power plants are designed to protect the core following a LOCA by providing a continuous supply of cooling water to the core. In the long term, the Refueling Water Storage Tank (RWST) inventory will be depleted and core heat removal accomplished via recirculation of water previously injected into the Reactor Coolant System (RCS) and collected in the containment sump. Debris generated within the containment as a result of the impingement of fluid jets in the Zone of Influence (ZOI) of the RCS break and containment wash down may find its way into the containment sump. As the safety injection pumps take suction from the sump, in the recirculation mode of operation, the debris suspended in the sump water could begin to accumulate in the sump screen that is located in the recirculation path. Should sufficient debris accumulate on the sump screen, a flow blockage could potentially develop. This would result in insufficient safety injection pump NPSH, thereby impairing the recirculation mode of injection into RCS. Potential debris blockage and prevention of sump recirculation may be addressed by refilling the RWST with water and injecting this water directly into the core. This paper identifies and attempts to resolve several issues related to this alternative mode of RCS injection. In particular, the

A multi-pathway model for photosynthetic reaction center

International Nuclear Information System (INIS)

Qin, M.; Shen, H. Z.; Yi, X. X.

2016-01-01

Charge separation occurs in a pair of tightly coupled chlorophylls at the heart of photosynthetic reaction centers of both plants and bacteria. Recently it has been shown that quantum coherence can, in principle, enhance the efficiency of a solar cell, working like a quantum heat engine. Here, we propose a biological quantum heat engine (BQHE) motivated by Photosystem II reaction center (PSII RC) to describe the charge separation. Our model mainly considers two charge-separation pathways which is more than that typically considered in the published literature. We explore how these cross-couplings increase the current and power of the charge separation and discuss the effects of multiple pathways in terms of current and power. The robustness of the BQHE against the charge recombination in natural PSII RC and dephasing induced by environments is also explored, and extension from two pathways to multiple pathways is made. These results suggest that noise-induced quantum coherence helps to suppress the influence of acceptor-to-donor charge recombination, and besides, nature-mimicking architectures with engineered multiple pathways for charge separations might be better for artificial solar energy devices considering the influence of environments.

Numerical simulation of RCS for carrier electronic warfare airplanes

OpenAIRE

Yue Kuizhi; Liu Wenlin; Li Guanxiong; Ji Jinzu; Yu Dazhao

2015-01-01

This paper studies the radar cross section (RCS) of carrier electronic warfare airplanes. Under the typical naval operations section, the mathematical model of the radar wave’s pitch angle incidence range analysis is established. Based on the CATIA software, considering dynamic deflections of duck wing leading edge flaps, flaperons, horizontal tail, and rudder, as well as aircraft with air-to-air missile, anti-radiation missile, electronic jamming pod, and other weapons, the 3D models of carr...

Accumulation of neurocan, a brain chondroitin sulfate proteoglycan, in association with the retinal vasculature in RCS rats.

Science.gov (United States)

Zhang, Yiqin; Rauch, Uwe; Perez, Maria-Thereza R

2003-03-01

To examine whether and how the retinal distribution of the chondroitin sulfate proteoglycan neurocan is affected after photoreceptor cell loss and whether it correlates with the multiple secondary cellular changes that accompany the photoreceptor degeneration. Retinas from normal rats (Sprague-Dawley; postnatal days [P]0-P70), RCS rats with dystrophic retinas (P0-P300), RCS-rdy(+) congenic rats with nondystrophic retinas (P0-202), and rhodopsin mutant rats, P23H (P0-P257) and S334ter (P0-P220), were processed for immunohistochemistry using a polyclonal antibody to rat neurocan. The overall distribution of neurocan was similar in all retinas examined. Neurocan immunostaining was detected over the nerve fiber layer, the plexiform layers, the photoreceptor outer segments region, and the ciliary epithelium. With age, labeling throughout the plexiform layers decreased continuously. In RCS rats however, conspicuous labeling was also seen in association with retinal vessels, from P15 onward. Accumulation of neurocan in association with the retinal vasculature does not correlate with photoreceptor cell loss, because it was not observed in the rhodopsin mutant rats. During the earliest stages of the disease, accumulation of debris in the subretinal space in RCS rats may be sufficient per se to initiate a cascade of metabolic changes that result in accumulation of neurocan. With time, the neurocan accumulated perivascularly may, by interaction with other matrix molecules, modulate at least some of the vascular alterations observed in this animal model.

Changes of the vasculature and innervation in the anterior segment of the RCS rat eye.

Science.gov (United States)

May, Christian Albrecht

2011-12-01

Investigating the anterior eye segment vasculature and innervation of dystrophic RCS rats, two major unique findings were observed: in the iris, young adult animals with retinal dystrophy showed an increase in substance P nerve fibres and a dilation of arterioles and capillaries. This finding continued during ageing. In the pars plana region, the surface covered by venules decreased continuously with age. In older animals, this decrease was parallelled by a local decrease of sympathetic TH-positive nerve fibres supplying these venules. For both conditions, no comparable data exists so far in the literature. They might point to a unique situation in the anterior eye segment of the dystrophic RCS rat. Copyright © 2011 Elsevier Ltd. All rights reserved.

Metal radomes for reduced RCS performance

Science.gov (United States)

Wahid, M.; Morris, S. B.

A frequency selective surface (FSS) comprising a square grid and a hexagonal array of disks is proposed as a means of reducing the Radar Cross Section (RCS) of a radar bay over a wide (2 GHz to 14.6 GHz) frequency bandwidth. Results are presented in terms of transmission loss for an 'A'-type sandwich radome consisting of two FSS layers for normal and non-normal incidence. A single FSS layer on a GRP flat panel is also considered. Good agreement is found between the predicted and measured results. The proposed FSS shows good performance and is relatively insensitive to angle of incidence between 3.8 GHz and 10.1 GHz. Predicted Insertion Phase Delay (IPD) and cross-polar performances are also given. Parametric studies have indicated the versatility of the proposed structure.

Cone function studied with flicker electroretinogram during progressive retinal degeneration in RCS rats.

Science.gov (United States)

Pinilla, I; Lund, R D; Sauvé, Y

2005-01-01

The Royal College of Surgeons (RCS) rat has a primary defect in retinal pigment epithelial cells that leads to the progressive loss of photoreceptors and central visual responsiveness. While most rods are lost by 90 days of age (P90), cones degenerate more slowly, and can be detected anatomically up to 2 years of age, despite massive neuronal death and retinal remodelling. To examine how this progressive degenerative process impacts on cone function, we recorded the electroretingram to white light flashes (1.37 log cd s m(-2)) presented at frequencies ranging from 3 to 50 Hz, under light adapted conditions (29.8 cd m(-2)). Pigmented dystrophic and congenic non-dystrophic RCS rats aged from 18 to 300 days were studied. In all responsive animals at all ages, maximal amplitudes were obtained at 3 Hz. In both non-dystrophic and dystrophic rats, there was an increase from P18 to P21 in response amplitude and critical fusion frequency. After P21, these two parameters declined progressively with age in dystrophic rats. Other changes included prolongation in latency, which was first detected prior to the initiation of amplitude reduction. While phase shifts were also detected in dystrophic RCS rats, they appeared at later degenerative stages. The latest age at which responses could be elicited in dystrophic rats was at P200, with positive waves being replaced by negative deflections. The effect of increments in the intensity of background illumination was tested at P50 in both groups. This caused a diminution in flicker response amplitude and critical fusion frequencies in non-dystrophics, while in dystrophic animals, response amplitudes were reduced only at low frequencies and critical fusion frequencies were unaltered. In conclusion, although dystrophic RCS rats undergo a progressive decline in cone function with age, the flicker responsiveness at P21 is comparable to that of non-dystrophic congenic rats, suggesting normal developmental maturation of the cone system in

Seismic analysis of APR1400 RCS for site envelope using big mass method

International Nuclear Information System (INIS)

Kim, J. Y.; Jeon, J. H.; Lee, D. H.; Park, S. H.

2002-01-01

One of design concepts of APR1400 is the site envelope considering various soil sites as well as rock site. The KSNP's are constructed on the rock site where only the translational excitations are directly transferred to the plant. On the other hand, the rotational motions affect the responses of the structures in the soil cases. In this study, a Big Mass Method is used to consider rotational motions as excitations at the foundation in addition to translational ones to obtain seismic responses of the APR1400 RCS main components. The seismic analyses for the APR1400 excited simultaneously by translation and rotational motions were performed. The results show that the effect of soil sites is not significant for the design of main components and supports of the RCS, but it may be considerable for the design of reactor vessel internals, piping, and nozzles which have lower natural frequencies

Electrophysiological studies of the feasibility of suprachoroidal-transretinal stimulation for artificial vision in normal and RCS rats.

Science.gov (United States)

Kanda, Hiroyuki; Morimoto, Takeshi; Fujikado, Takashi; Tano, Yasuo; Fukuda, Yutaka; Sawai, Hajime

2004-02-01

Assessment of a novel method of retinal stimulation, known as suprachoroidal-transretinal stimulation (STS), which was designed to minimize insult to the retina by implantation of stimulating electrodes for artificial vision. In 17 normal hooded rats and 12 Royal College of Surgeons (RCS) rats, a small area of the retina was focally stimulated with electric currents through an anode placed on the fenestrated sclera and a cathode inserted into the vitreous chamber. Evoked potentials (EPs) in response to STS were recorded from the surface of the superior colliculus (SC) with a silver-ball electrode, and their physiological properties and localization were studied. In both normal and RCS rats, STS elicited triphasic EPs that were vastly diminished by changing polarity of stimulating electrodes and abolished by transecting the optic nerve. The threshold intensity (C) of the EP response to STS was approximately 7.2 +/- 2.8 nC in normal and 12.9 +/- 7.7 nC in RCS rats. The responses to minimal STS were localized in an area on the SC surface measuring 0.12 +/- 0.07 mm(2) in normal rats and 0.24 +/- 0.12 mm(2) in RCS rats. The responsive area corresponded retinotopically to the retinal region immediately beneath the anodic stimulating electrode. STS is less invasive in the retina than stimulation through epiretinal or subretinal implants. STS can generate focal excitation in retinal ganglion cells in normal animals and in those with degenerated photoreceptors, which suggests that this method of retinal stimulation is suitable for artificial vision.

Calculation of beam neutralization in the IPNS-Upgrade RCS

International Nuclear Information System (INIS)

Chae, Yong-Chul.

1995-01-01

The author calculated the neutralization of circulating beam in this report. In the calculation it is assumed that all electrons liberated from the background molecules due to the collisional processes are trapped in the potential well of the proton beam. Including the dependence of ionization cross sections on the kinetic energy of the incident particle, the author derived the empirical formula for beam neutralization as a function of time and baseline vacuum pressure, which is applicable to the one acceleration cycle of the IPNS-Upgrade RCS

A comparison on radar range profiles between in-flight measurements and RCS-predictions

NARCIS (Netherlands)

Heiden, R. van der; Ewijk, L.J. van; Groen, F.C.A.

1998-01-01

The validation of Radar Cross Section (RCS) prediction techniques against real measurements is crucial to acquire confidence in predictions when measurements are nut available. In this paper we present the results of a comparison on one-dimensional signatures, i.e. radar range profiles. The profiles

Vasovagal reactions in whole blood donors at 3 REDS-II blood centers in Brazil

Science.gov (United States)

Goncalez, T. T.; Sabino, E. C.; Schlumpf, K.S.; Wright, D.J.; Leao, S.; Sampaio, D.; Takecian, P. L.; Carneiro-Proietti, AB; Murphy, E.; Busch, M.; Custer, B.

2013-01-01

Background In Brazil little is known about adverse reactions during donation and the donor characteristics that may be associated with such events. Donors are offered snacks and fluids prior to donating and are required to consume a light meal after donation. For these reasons the frequency of reactions may be different than those observed in other countries. Methods A cross-sectional study was conducted of eligible whole blood donors at three large blood centers located in Brazil between July 2007 and December 2009. Vasovagal reactions (VVRs) along with donor demographic and biometric data were collected. Reactions were defined as any presyncopal or syncopal event during the donation process. Multivariable logistic regression was performed to identify predictors of VVRs. Results Of 724,861 donor presentations, 16,129 (2.2%) VVRs were recorded. Rates varied substantially between the three centers: 53, 290 and 381 per 10,000 donations in Recife, São Paulo and Belo Horizonte, respectively. Although the reaction rates varied, the donor characteristics associated with VVRs were similar [younger age (18–29), replacement donors, first time donors, low estimated blood volume (EBV)]. In multivariable analysis controlling for differences between the donor populations in each city younger age, first-time donor status and lower EBV were the factors most associated with reactions. Conclusion Factors associated with VVRs in other locations are also evident in Brazil. The difference in VVR rates between the three centers might be due to different procedures for identifying and reporting the reactions. Potential interventions to reduce the risk of reactions in Brazil should be considered. PMID:22073941

Co-ordination of the nuclear reaction data centers. Report on an IAEA advisory group meeting

International Nuclear Information System (INIS)

Schwerer, O.; Lemmel, H.D.

1996-11-01

This report summarizes the 1996 co-ordination meeting in Brookhaven, U.S.A., of the national and regional nuclear reaction data center, convened by the IAEA at regular intervals. The main topics are: the international exchange of nuclear reaction data by means of the ''EXFOR'' system, and the further development of this system; the ''CINDA'' system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable nuclear data compilation and data center services; the exchange and documentation of evaluated data libraries in ''ENDF'' format; the rapid advances of online electronic information technologies, with the goal of rendering data center services to data users in IAEA Member States by means of computer retrievals, online services and printed materials. The scope of data covers microscopic cross-sections and related parameters of nuclear reactions induced by neutrons, charged-particles and photons. (author). Refs, figs, tabs

Co-ordination of the nuclear reactions data centers. Report on an IAEA advisory group meeting

International Nuclear Information System (INIS)

Pronyaev, V.G.; Schwerer, O.

1998-07-01

This report summarizes the 1998 co-ordination meeting at the IAEA Headquarters in Vienna of the regional, national and specialized nuclear reaction data centers, concerned by the IAEA at two-year intervals. The main topics are: the international exchange of nuclear reaction data by means of the ''EXFOR'' system, and the further development of this system; the ''CINDA'' system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable nuclear data compilation and data center services; the exchange and documentation of evaluated data libraries in ''ENDF'' format; the rapid advances of online electronic information technologies, with goal of rendering data center services to data users in IAEA Member States by means of computer retrievals, online services and printed materials. The scope of data covers microscopic cross-sections and related parameters of nuclear reactions induced by neutrons, charged-particles and photons. (author)

Co-ordination of the nuclear reaction data centers. Report on an IAEA advisory group meeting

Energy Technology Data Exchange (ETDEWEB)

Schwerer, O; Lemmel, H D [eds.

1996-11-01

This report summarizes the 1996 co-ordination meeting in Brookhaven, U.S.A., of the national and regional nuclear reaction data center, convened by the IAEA at regular intervals. The main topics are: the international exchange of nuclear reaction data by means of the ``EXFOR`` system, and the further development of this system; the ``CINDA`` system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable nuclear data compilation and data center services; the exchange and documentation of evaluated data libraries in ``ENDF`` format; the rapid advances of online electronic information technologies, with the goal of rendering data center services to data users in IAEA Member States by means of computer retrievals, online services and printed materials. The scope of data covers microscopic cross-sections and related parameters of nuclear reactions induced by neutrons, charged-particles and photons. (author). Refs, figs, tabs.

The breakdown of vinyl ethers as a two-center synchronous reaction

Science.gov (United States)

Pokidova, T. S.; Shestakov, A. F.

2009-11-01

The experimental data on the molecular decomposition of vinyl ethers of various structures to alkanes and the corresponding aldehydes or ketones in the gas phase were analyzed using the method of intersecting parabolas. The enthalpies and kinetic parameters of decomposition were calculated for 17 reactions. The breakdown of ethers is a two-center concerted reaction characterized by a very high classical potential barrier to the thermally neutral reaction (180-190 kJ/mol). The kinetic parameters (activation energies and rate constants) of back reactions of the formation of vinyl ethers in the addition of aldehydes or ketones to alkanes were calculated using the method of intersecting parabolas. The factors that influenced the activation energy of the decomposition and formation of ethers were discussed. Quantum-chemical calculations of several vinyl ether decomposition reactions were performed. Ether formation reactions were compared with the formation of unsaturated alcohols as competitive reactions, which can occur in the interaction of carbonyl compounds with alkenes.

Pressure-Fed LOX/LCH4 Reaction Control System for Spacecraft: Transient Modeling and Thermal Vacuum Hotfire Test Results

Science.gov (United States)

Atwell, Matthew J.; Hurlbert, Eric A.; Melcher, J. C.; Morehead, Robert L.

2017-01-01

An integrated cryogenic liquid oxygen, liquid methane (LOX/LCH4) reaction control system (RCS) was tested at NASA Glenn Research Center's Plum Brook Station in the Spacecraft Propulsion Research Facility (B-2) under vacuum and thermal vacuum conditions. The RCS is a subsystem of the Integrated Cryogenic Propulsion Test Article (ICPTA), a pressure-fed LOX/LCH4 propulsion system composed of a single 2,800 lbf main engine, two 28 lbf RCS engines, and two 7 lbf RCS engines. Propellants are stored in four 48 inch diameter 5083 aluminum tanks that feed both the main engine and RCS engines in parallel. Helium stored cryogenically in a composite overwrapped pressure vessel (COPV) flows through a heat exchanger on the main engine before being used to pressurize the propellant tanks to a design operating pressure of 325 psi. The ICPTA is capable of simultaneous main engine and RCS operation. The RCS engines utilize a coil-on-plug (COP) ignition system designed for operation in a vacuum environment, eliminating corona discharge issues associated with a high voltage lead. There are two RCS pods on the ICPTA, with two engines on each pod. One of these two engines is a heritage flight engine from Project Morpheus. Its sea level nozzle was removed and replaced by an 85:1 nozzle machined using Inconel 718, resulting in a maximum thrust of 28 lbf under altitude conditions. The other engine is a scaled down version of the 28 lbf engine, designed to match the core and overall mixture ratios as well as other injector characteristics. This engine can produce a maximum thrust of 7 lbf with an 85:1 nozzle that was additively manufactured using Inconel 718. Both engines are film-cooled and capable of limited duration gas-gas and gas-liquid operation, as well as steady-state liquid-liquid operation. Each pod contains one of each version, such that two engines of the same thrust level can be fired as a couple on opposite pods. The RCS feed system is composed of symmetrical 3/8 inch lines

Co-ordination of the nuclear reactions data centers. Report on an IAEA advisory group meeting

Energy Technology Data Exchange (ETDEWEB)

Pronyaev, V G; Schwerer, O [eds.

1998-07-01

This report summarizes the 1998 co-ordination meeting at the IAEA Headquarters in Vienna of the regional, national and specialized nuclear reaction data centers, concerned by the IAEA at two-year intervals. The main topics are: the international exchange of nuclear reaction data by means of the ``EXFOR`` system, and the further development of this system; the ``CINDA`` system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable nuclear data compilation and data center services; the exchange and documentation of evaluated data libraries in ``ENDF`` format; the rapid advances of online electronic information technologies, with goal of rendering data center services to data users in IAEA Member States by means of computer retrievals, online services and printed materials. The scope of data covers microscopic cross-sections and related parameters of nuclear reactions induced by neutrons, charged-particles and photons. (author) Refs, figs, tabs

Regulations, Codes, and Standards (RCS) Template for California Hydrogen Dispensing Stations

Energy Technology Data Exchange (ETDEWEB)

Rivkin, C.; Blake, C.; Burgess, R.; Buttner, W.; Post, M.

2012-11-01

This report explains the Regulations, Codes, and Standards (RCS) requirements for hydrogen dispensing stations in the State of California. The reports shows the basic components of a hydrogen dispensing station in a simple schematic drawing; the permits and approvals that would typically be required for the construction and operation of a hydrogen dispensing station; and a basic permit that might be employed by an Authority Having Jurisdiction (AHJ).

In situ degassing of the kicker magnet in J-PARC RCS

International Nuclear Information System (INIS)

Kamiya, Junichiro; Ogiwara, Norio; Hikichi, Yusuke; Yanagibashi, Toru; Kinsho, Michikazu

2015-01-01

The usual way to reduce outgassing from a device in vacuum is to heat up a whole vacuum chamber containing the device. However, the situation, where this method can be applied, is limited due to the heat expansion of the chamber. Especially in accelerators, where the vacuum chambers are connected with nearby beam pipes, this normal bake-out method may not be applied. If a heat source and heat shields are appropriately installed inside the chamber, heat flux is directed to the device. Therefore the device can be baked out without raising the temperature of the vacuum chamber. One candidate for such bake-out method to be applied is kicker magnets in J-PARC RCS, which are installed in large vacuum chambers. We performed the heating tests with some types of heaters in order to examine the effectiveness of this method and to decide the material and configuration of the heater. As a result, the graphite heater was selected for in-situ bake-out of the kickers in the RCS beam line. Using the method, the each material of kicker magnet was heated up above 100degC with keeping the temperature rise of the vacuum chamber below 30degC. (author)

Molar extinction coefficients and other properties of an improved reaction center preparation from Rhodopseudomonas viridis

Energy Technology Data Exchange (ETDEWEB)

Clayton, R.K.; Clayton, B.J.

1978-01-01

Reaction centers have been purified from chromatophores of Rhodopseudomonas viridis by treatment with lauryl dimethyl amine oxide followed by hydroxyapatite chromatography and precipitation with ammonium sulfate. The absorption spectrum at low temperature shows bands at 531 and 543 nm, assigned to two molecules of bacteriopheophytin b. The 600 nm band of bacteriochlorophyll b is resolved at low temperature into components at 601 and 606.5 nm. At room temperature the light-induced difference spectrum shows a negative band centered at 615 nm, where the absorption spectrum shows only a week shoulder adjacent to the 600 nm band. The fluorescence spectrum shows a band at 1000 nm and no fluorescence corresponding to the 830 nm absorption band. Two molecules of cytochrome 558 and three of cytochrome 552 accompany each reaction center. The differential extinction coefficient (reduced minus oxidized) of cytochrome 558 nm was estimated as 20 +- 2 mM/sup -1/.cm/sup -1/ through a coupled reaction with equine cytochrome c. The extinction coefficient of reaction centers at 960 nm was determined to be 123 +- 25 mM/sup -1/.cm/sup -1/ by measuring the light-induced bleaching of P-960 and the coupled oxidation of cytochrome 558. The corresponding extinction coefficient at 830 nm is 300 +- 65 mM/sup -1/.cm/sup -1/. The absorbance ratio ..cap alpha../sub 280nm/..cap alpha../sub 830nm/ in our preparations was 2.1, and there was 190 kg protein per mol of reaction centers. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed three major components of apparent molecular weights 31,000, 37,000, and 41,000.

Homeostatic Plasticity Mediated by Rod-Cone Gap Junction Coupling in Retinal Degenerative Dystrophic RCS Rats

Science.gov (United States)

Hou, Baoke; Fu, Yan; Weng, Chuanhuang; Liu, Weiping; Zhao, Congjian; Yin, Zheng Qin

2017-01-01

Rod-cone gap junctions open at night to allow rod signals to pass to cones and activate the cone-bipolar pathway. This enhances the ability to detect large, dim objects at night. This electrical synaptic switch is governed by the circadian clock and represents a novel form of homeostatic plasticity that regulates retinal excitability according to network activity. We used tracer labeling and ERG recording in the retinae of control and retinal degenerative dystrophic RCS rats. We found that in the control animals, rod-cone gap junction coupling was regulated by the circadian clock via the modulation of the phosphorylation of the melatonin synthetic enzyme arylalkylamine N-acetyltransferase (AANAT). However, in dystrophic RCS rats, AANAT was constitutively phosphorylated, causing rod-cone gap junctions to remain open. A further b/a-wave ratio analysis revealed that dystrophic RCS rats had stronger synaptic strength between photoreceptors and bipolar cells, possibly because rod-cone gap junctions remained open. This was despite the fact that a decrease was observed in the amplitude of both a- and b-waves as a result of the progressive loss of rods during early degenerative stages. These results suggest that electric synaptic strength is increased during the day to allow cone signals to pass to the remaining rods and to be propagated to rod bipolar cells, thereby partially compensating for the weak visual input caused by the loss of rods. PMID:28473754

Role of Rhodobacter sphaeroides photosynthetic reaction center residue M214 in the composition, absorbance properties, and conformations of H(A) and B(A) cofactors.

Science.gov (United States)

Saer, Rafael G; Hardjasa, Amelia; Rosell, Federico I; Mauk, A Grant; Murphy, Michael E P; Beatty, J Thomas

2013-04-02

In the native reaction center (RC) of Rhodobacter sphaeroides, the side chain of (M)L214 projects orthogonally toward the plane and into the center of the A branch bacteriopheophytin (BPhe) macrocycle. The possibility that this side chain is responsible for the dechelation of the central Mg(2+) of bacteriochlorophyll (BChl) was investigated by replacement of (M)214 with residues possessing small, nonpolar side chains that can neither coordinate nor block access to the central metal ion. The (M)L214 side chain was also replaced with Cys, Gln, and Asn to evaluate further the requirements for assembly of the RC with BChl in the HA pocket. Photoheterotrophic growth studies showed no difference in growth rates of the (M)214 nonpolar mutants at a low light intensity, but the growth of the amide-containing mutants was impaired. The absorbance spectra of purified RCs indicated that although absorbance changes are associated with the nonpolar mutations, the nonpolar mutant RC pigment compositions are the same as in the wild-type protein. Crystal structures of the (M)L214G, (M)L214A, and (M)L214N mutants were determined (determined to 2.2-2.85 Å resolution), confirming the presence of BPhe in the HA pocket and revealing alternative conformations of the phytyl tail of the accessory BChl in the BA site of these nonpolar mutants. Our results demonstrate that (i) BChl is converted to BPhe in a manner independent of the aliphatic side chain length of nonpolar residues replacing (M)214, (ii) BChl replaces BPhe if residue (M)214 has an amide-bearing side chain, (iii) (M)214 side chains containing sulfur are not sufficient to bind BChl in the HA pocket, and (iv) the (M)214 side chain influences the conformation of the phytyl tail of the BA BChl.

Error Analysis of Relative Calibration for RCS Measurement on Ground Plane Range

Directory of Open Access Journals (Sweden)

Wu Peng-fei

2012-03-01

Full Text Available Ground plane range is a kind of outdoor Radar Cross Section (RCS test range used for static measurement of full-size or scaled targets. Starting from the characteristics of ground plane range, the impact of environments on targets and calibrators is analyzed during calibration in the RCS measurements. The error of relative calibration produced by the different illumination of target and calibrator is studied. The relative calibration technique used in ground plane range is to place the calibrator on a fixed and auxiliary pylon somewhere between the radar and the target under test. By considering the effect of ground reflection and antenna pattern, the relationship between the magnitude of echoes and the position of calibrator is discussed. According to the different distances between the calibrator and target, the difference between free space and ground plane range is studied and the error of relative calibration is calculated. Numerical simulation results are presented with useful conclusions. The relative calibration error varies with the position of calibrator, frequency and antenna beam width. In most case, set calibrator close to the target may keep the error under control.

Determination of the excitation migration time in Photosystem II consequences for the membrane organization and charge separation parameters

NARCIS (Netherlands)

Broess, K.; Trinkunas, G.; Hoek, van A.; Croce, R.; Amerongen, van H.

2008-01-01

The fluorescence decay kinetics of Photosystem II (PSII) membranes from spinach with open reaction centers (RCs), were compared after exciting at 420 and 484 nm. These wavelengths lead to preferential excitation of chlorophyll (Chl) a and Chl b, respectively, which causes different initial

Determination of the excitation migration time in Photosystem II - Consequences for the membrane organization and charge separation parameters

NARCIS (Netherlands)

Broess, Koen; Trinkunas, Gediminas; van Hoek, Arie; Croce, Roberta; van Amerongen, Herbert

The fluorescence decay kinetics of Photosystem II (PSII) membranes from spinach with open reaction centers (RCs), were compared after exciting at 420 and 484 nm. These wavelengths lead to preferential excitation of chlorophyll (Chl) a and Chl b, respectively, which causes different initial

Observations of a cold front with strong vertical undulations during the ARM RCS-IOP

Energy Technology Data Exchange (ETDEWEB)

Starr, D.O`C.; Whiteman, D.N. [Goddard Space Flight Center, Greenbelt, MD (United States); Melfi, S.H. [Univ. of Maryland, Baltimore, MD (United States)] [and others

1996-04-01

Passage of a cold front was observed on the night of April 14-15, 1994, during the Atmospheric Radiation Measurement (ARM) Remote Cloud Sensing (RCS) Intensive Observatios Period (IOP) at the Southern Great Plains Cloud and Radiation Testbed (CART) site near Lamont, Oklahoma. The observations are described.

Evaluation of a coolant injection into the in-vessel with a RCS depressurization by using SCDAP/RELAP5

International Nuclear Information System (INIS)

Rae-Joon, Park; Sang-Baik, Kim; Hee-Dong, Kim

2007-01-01

As part of the evaluations of a severe accident management strategy, a coolant injection in the vessel with a reactor coolant system (RCS) depressurization has been evaluated by using the SCDAP/RELAP5 computer code. Two high pressure sequences of a small break loss of coolant accident (LOCA) without safety injection (SI) and a total loss of feed water (LOFW) accident have been analyzed in optimized power reactor OPR-1000. The SCDAP/RELAP5 results have shown that only one train operation of a high pressure safety injection at 30,000 seconds with a RCS depressurization by using one condenser dump valve at 6 minutes after an entrance of the severe accident management guidance prevents a reactor vessel failure for the small break LOCA without SI. In this case, only train operation of the low pressure safety injection (LPSI) without the high pressure safety injection (HPSI) does not prevent a reactor vessel failure. Only one train operation of the HPSI at 20,208 seconds with a RCS depressurization by using two safety depressurization system valves at 40 minutes after an initial opening of the safety relief valve prevents a reactor vessel failure for the total LOFW. (authors)

Biomimetic Membranes for Multi-Redox Center Proteins

Directory of Open Access Journals (Sweden)

Renate L. C. Naumann

2016-03-01

Full Text Available His-tag technology was applied for biosensing purposes involving multi-redox center proteins (MRPs. An overview is presented on various surfaces ranging from flat to spherical and modified with linker molecules with nitrile-tri-acetic acid (NTA terminal groups to bind his-tagged proteins in a strict orientation. The bound proteins are submitted to in situ dialysis in the presence of lipid micelles to form a so-called protein-tethered bilayer lipid membrane (ptBLM. MRPs, such as the cytochrome c oxidase (CcO from R. sphaeroides and P. denitrificans, as well as photosynthetic reactions centers (RCs from R. sphaeroides, were thus investigated. Electrochemical and surface-sensitive optical techniques, such as surface plasmon resonance, surface plasmon-enhanced fluorescence, surface-enhanced infrared absorption spectroscopy (SEIRAS and surface-enhanced resonance Raman spectroscopy (SERRS, were employed in the case of the ptBLM structure on flat surfaces. Spherical particles ranging from µm size agarose gel beads to nm size nanoparticles modified in a similar fashion were called proteo-lipobeads (PLBs. The particles were investigated by laser-scanning confocal fluorescence microscopy (LSM and UV/Vis spectroscopy. Electron and proton transfer through the proteins were demonstrated to take place, which was strongly affected by the membrane potential. MRPs can thus be used for biosensing purposes under quasi-physiological conditions.

Grafting of ARPE-19 and Schwann cells to the subretinal space in RCS rats.

Science.gov (United States)

Wang, Shaomei; Lu, Bin; Wood, Patrick; Lund, Raymond D

2005-07-01

To study the distribution of the human retinal pigment epithelium (hRPE) cell line ARPE-19 and human Schwann (hSC) cells grafted to the subretinal space of the Royal College of Surgeon (RCS) rat and the relation of graft cell distribution to photoreceptor rescue. Cell suspensions of both donor types were injected into the subretinal space of 3-week-old dystrophic RCS rats through a transscleral approach, human fibroblast and medium were used as control grafts. All animals were maintained on oral cyclosporine. At 1, 2, 4, 6, 15, 28, and 36 weeks after grafting, animals were killed. Human cell-specific markers were used to localize donor cells. Both donor cell types, as revealed by antibodies survived for a substantial time. Their distribution was very different: hRPE cells formed a large clump early on and, with time, spread along the host RPE in a layer one to two cells deep, whereas hSCs formed many smaller clumps, mainly in the subretinal space. Both cells rescued photoreceptors beyond the area of donor cell distribution. The number of surviving cells declined with time. Both hRPE and hSC grafts can survive and rescue photoreceptors for a substantial time after grafting. The number of both donor cell types declined with time, which could be an immune-related problem and/or due to other factors intrinsic to the host RCS retina. The fact that rescue occurred beyond the area of donor cell distribution suggests that diffusible factors are involved, raising the possibility that the two cell types function in a similar manner to rescue photoreceptors.

Interface for Light-Driven Electron Transfer by Photosynthetic Complexes Across Block Copolymer Membranes.

Science.gov (United States)

Kuang, Liangju; Olson, Tien L; Lin, Su; Flores, Marco; Jiang, Yunjiang; Zheng, Wan; Williams, JoAnn C; Allen, James P; Liang, Hongjun

2014-03-06

Incorporation of membrane proteins into nanodevices to mediate recognition and transport in a collective and scalable fashion remains a challenging problem. We demonstrate how nanoscale photovoltaics could be designed using robust synthetic nanomembranes with incorporated photosynthetic reaction centers (RCs). Specifically, RCs from Rhodobacter sphaeroides are reconstituted spontaneously into rationally designed polybutadiene membranes to form hierarchically organized proteopolymer membrane arrays via a charge-interaction-directed reconstitution mechanism. Once incorporated, the RCs are fully active for prolonged periods based upon a variety of spectroscopic measurements, underscoring preservation of their 3D pigment configuration critical for light-driven charge transfer. This result provides a strategy to construct solar conversion devices using structurally versatile proteopolymer membranes with integrated RC functions to harvest broad regions of the solar spectrum.

Determination of the excitation migration time in Photosystem II. Consequences for the membrane organization and charge separation parameters

NARCIS (Netherlands)

Broess, Koen; Trinkunas, Gediminas; van Hoek, Arie; Croce, Roberta; van Amerongen, Herbert

The fluorescence decay kinetics of Photosystem II (PSII) membranes from spinach with open reaction centers (RCs), were compared after exciting at 420 and 484 nm. These wavelengths lead to preferential excitation of chlorophyll (Chl) a and Chl b, respectively, which causes different initial

Constitutively reduced sensory capacity promotes better recovery after spinal cord-injury (SCI) in blind rats of the dystrophic RCS strain.

Science.gov (United States)

Rink, Svenja; Bendella, Habib; Alsolivany, Kurdin; Meyer, Carolin; Woehler, Aliona; Jansen, Ramona; Isik, Zeynep; Stein, Gregor; Wennmachers, Sina; Nakamura, Makoto; Angelov, Doychin N

2018-01-01

We compared functional, electrophysiological and morphological parameters after SCI in two groups of rats Sprague Dawley (SD) rats with normal vision and blind rats from a SD-substrain "Royal College of Surgeons" (SD/RCS) who lose their photoreceptor cells after birth due to a genetic defect in the retinal pigment epithelium. For these animals skin-, intramuscular-, and tendon receptors are major available means to resolve spatial information. The purpose of this study was to check whether increased sensitivity in SD/RCS rats would promote an improved recovery after SCI. All rats were subjected to severe compression of the spinal cord at vertebra Th8, spinal cord segment Th10. Recovery of locomotion was analyzed at 1, 3, 6, 9, and 12 weeks after SCI using video recordings of beam walking and inclined ladder climbing. Five functional parameters were studied: foot-stepping angle (FSA), rump-height index (RHI) estimating paw placement and body weight support, respectively, number of correct ladder steps (CLS) assessing skilled hindlimb movements, the BBB-locomotor score and an established urinary bladder score (BS). Sensitivity tests were followed by electrophysiological measurement of M- and H-wave amplitudes from contractions of the plantar musculature after stimulation of the tibial nerve. The closing morphological measurements included lesion volume and expression of astro- and microglia below the lesion. Numerical assessments of BBB, FSA, BS, lesion volume and GFAP-expression revealed no significant differences between both strains. However, compared to SD-rats, the blind SD/RCS animals significantly improved RHI and CLS by 6 - 12 weeks after SCI. To our surprise the withdrawal latencies in the blind SD/RCS rats were longer and the amplitudes of M- and H-waves lower. The expression of IBA1-immunoreactivity in the lumbar enlargement was lower than in the SD-animals. The longer withdrawal latencies suggest a decreased sensitivity in the blind SD/RCS rats, which

11. IAEA consultants' meeting of the nuclear reaction data centers. Obninsk, 7-11 October 1991

International Nuclear Information System (INIS)

Lemmel, H.D.

1992-03-01

This report summarizes the 1991 co-ordination meeting in Obninsk, Russia, of the national and regional nuclear reaction data centers, convened by the IAEA at regular intervals. The main topics are: the international exchange of nuclear reaction data by means of the ''EXFOR'' system, and the further development of this system; the ''CINDA'' system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable nuclear data compilation; the exchanged and documentation of evaluated data libraries in ENDF format, with the goal of rendering data center services to data users in IAEA Member States by means of computer retrievals, online services and printed materials

Molecular electronics of a single photosystem I reaction center: Studies with scanning tunneling microscopy and spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Lee, I.; Lee, J.W.; Warmack, R.J.; Allison, D.P.; Greenbaum, E. [Oak Ridge National Lab., TN (United States)

1995-03-14

Thylakoids and photosystem I (PSI) reaction centers were imaged by scanning tunneling microscopy. The thylakoids were isolated from spinach chloroplasts, and PSI reaction centers were extracted from thylakoid membranes. Because thylakoids are relatively thick nonconductors, they were sputter-coated with Pd/Au before imaging. PSI photosynthetic centers and chemically platinized PSI were investigated without sputter-coating. They were mounted on flat gold substrates that had been treated with mercaptoacetic acid to help bind the proteins. With tunneling spectroscopy, the PSI centers displayed a semiconductor-like response with a band gap of 1.8 eV. Lightly platinized (platinized for 1 hr) centers displayed diode-like conduction that resulted in dramatic contrast changes between images taken with opposite bias voltages. The electronic properties of this system were stable under long-term storage. 42 refs., 7 figs.

Alterations of sodium and potassium channels of RGCs in RCS rat with the development of retinal degeneration.

Science.gov (United States)

Chen, Zhongshan; Song, Yanping; Yao, Junping; Weng, Chuanhuang; Yin, Zheng Qin

2013-11-01

All know that retinitis pigmentosa (RP) is a group of hereditary retinal degenerative diseases characterized by progressive dysfunction of photoreceptors and associated with progressive cells loss; nevertheless, little is known about how rods and cones loss affects the surviving inner retinal neurons and networks. Retinal ganglion cells (RGCs) process and convey visual information from retina to visual centers in the brain. The healthy various ion channels determine the normal reception and projection of visual signals from RGCs. Previous work on the Royal College of Surgeons (RCS) rat, as a kind of classical RP animal model, indicated that, at late stages of retinal degeneration in RCS rat, RGCs were also morphologically and functionally affected. Here, retrograde labeling for RGCs with Fluorogold was performed to investigate the distribution, density, and morphological changes of RGCs during retinal degeneration. Then, patch clamp recording, western blot, and immunofluorescence staining were performed to study the channels of sodium and potassium properties of RGCs, so as to explore the molecular and proteinic basis for understanding the alterations of RGCs membrane properties and firing functions. We found that the resting membrane potential, input resistance, and capacitance of RGCs changed significantly at the late stage of retinal degeneration. Action potential could not be evoked in a part of RGCs. Inward sodium current and outward potassium current recording showed that sodium current was impaired severely but only slightly in potassium current. Expressions of sodium channel protein were impaired dramatically at the late stage of retinal degeneration. The results suggested that the density of RGCs decreased, process ramification impaired, and sodium ion channel proteins destructed, which led to the impairment of electrophysiological functions of RGCs and eventually resulted in the loss of visual function.

Localization and Developmental Expression Patterns of CSPG in the RCS Rat Retina

Directory of Open Access Journals (Sweden)

Li-Feng Chen

2011-05-01

Full Text Available Purpose: Investigate changes in chondroitin sulfate proteoglycan (CSPG distribution in Royal College of Surgeons (RCS rat retinae. Could CSPGs distribution act as a physical barrier to transplanted cell migration in degenerating retinae? Methods: CSPG expression was examined in RCS and Long-Evans rat retinae from birth to postnatal day 150 (PND150 using immunofluorescence and western-blots. Results: Both groups showed a rapid rise in CSPG expression on PND14, which peaked on PND21 before declining to lower levels by PND35. CSPG expression had risen again by PND90 and remained elevated for the duration of the study (PND150. However, from PND21, CSPG expression was significantly higher (p ≤ 0.05, n = 5 in Long-Evans rat retinae. CSPG-positive cells were localized in the ganglion cell layer (GCL and the photoreceptor outer segment debris zone (DZ; CSPG expression in the DZ was the main contributor to the higher expression in older animals for both groups. Conclusions: Increased expression of CSPGs in the DZ may act as a physical barrier following retinal cellular transplantation. CSPGs in the GCL is probably related to dendritic changes. CSPG accumulation in the older retinae suggests that aging influences the microenvironment in the retina, which may affect the efficacy of cell transplantation.

Possible sources of neuroprotection following subretinal silicon chip implantation in RCS rats

Science.gov (United States)

Pardue, Machelle T.; Phillips, Michael J.; Yin, Hang; Fernandes, Alcides; Cheng, Yian; Chow, Alan Y.; Ball, Sherry L.

2005-03-01

Current retinal prosthetics are designed to stimulate existing neural circuits in diseased retinas to create a visual signal. However, implantation of retinal prosthetics may create a neurotrophic environment that also leads to improvements in visual function. Possible sources of increased neuroprotective effects on the retina may arise from electrical activity generated by the prosthetic, mechanical injury due to surgical implantation, and/or presence of a chronic foreign body. This study evaluates these three neuroprotective sources by implanting Royal College of Surgeons (RCS) rats, a model of retinitis pigmentosa, with a subretinal implant at an early stage of photoreceptor degeneration. Treatment groups included rats implanted with active and inactive devices, as well as sham-operated. These groups were compared to unoperated controls. Evaluation of retinal function throughout an 18 week post-implantation period demonstrated transient functional improvements in eyes implanted with an inactive device at 6, 12 and 14 weeks post-implantation. However, the number of photoreceptors located directly over or around the implant or sham incision was significantly increased in eyes implanted with an active or inactive device or sham-operated. These results indicate that in the RCS rat localized neuroprotection of photoreceptors from mechanical injury or a chronic foreign body may provide similar results to subretinal electrical stimulation at the current output evaluated here.

Model of deep centers formation and reactions in electron irradiated InP

International Nuclear Information System (INIS)

Sibille, A.; Suski, J.; Gilleron, M.

1986-01-01

We present a model of the production of deep centers and their reactions following electron irradiations in InP. We propose that the dominant hole traps in p-InP and electron traps in p + n InP junctions are complexes between shallow acceptors and a common intrinsic entity, the phosphorus interstitial or vacancy. The reactions observed below and above room temperature are then due to a local mobility of this entity, which can be obtained as well by thermal as by electronic stimulation of the reactions. This model implies the long-range migration (at least down to 16 K) of this entity, and explains the strongly different behavior of n-InP compared to p-InP samples

A Hybrid Optimization Algorithm for Low RCS Antenna Design

Directory of Open Access Journals (Sweden)

W. Shao

2012-12-01

Full Text Available In this article, a simple and efficient method is presented to design low radar cross section (RCS patch antennas. This method consists of a hybrid optimization algorithm, which combines a genetic algorithm (GA with tabu search algorithm (TSA, and electromagnetic field solver. The TSA, embedded into the GA frame, defines the acceptable neighborhood region of parameters and screens out the poor-scoring individuals. Thus, the repeats of search are avoided and the amount of time-consuming electromagnetic simulations is largely reduced. Moreover, the whole design procedure is auto-controlled by programming the VBScript language. A slot patch antenna example is provided to verify the accuracy and efficiency of the proposed method.

Improvement on RCS reduction using flat lossy focusing reflectors.

Science.gov (United States)

Chin, Cheng-Yuan; Jou, Christina F

2013-12-30

In this paper, we propose a planar non-periodic subwavelength resistive grating (SWRG). The phase front of the scattered fields can be completely manipulated through non-periodic design of the grating while high absorptivity is preserved. The SWRG has an interesting property similar to a resistive concave reflecting lens. Scattered wave is focused in the near-field region, and spread out in the far-field. This feature of non-periodic resistive grating can improve the original radar cross section (RCS) reduction up to 22.86 dB in the boresight direction comparing to the periodic counterpart. Non-periodic design of SWRG could have a substantial impact on stealth technology, aerospace engineering, and microwave anechoic chamber.

The effects of light-induced reduction of the photosystem II reaction center

Czech Academy of Sciences Publication Activity Database

Kutý, Michal

2009-01-01

Roč. 8, č. 15 (2009), s. 923-933 ISSN 1610-2940 R&D Projects: GA MŠk(CZ) LC06010 Institutional research plan: CEZ:AV0Z60870520 Keywords : Photosystem II * Reaction center * Pheophytin Subject RIV: CE - Biochemistry Impact factor: 2.336, year: 2009

World Register of marine Cave Species (WoRCS: a new Thematic Species Database for marine and anchialine cave biodiversity

Directory of Open Access Journals (Sweden)

Vasilis Gerovasileiou

2016-09-01

Full Text Available Scientific exploration of marine cave environments and anchialine ecosystems over recent decades has led to outstanding discoveries of novel taxa, increasing our knowledge of biodiversity. However, biological research on underwater caves has taken place only in a few areas of the world and relevant information remains fragmented in isolated publications and databases. This fragmentation makes assessing the conservation status of marine cave species especially problematic, and this issue should be addressed urgently given the stresses resulting from planned and rampant development in the coastal zone worldwide. The goal of the World Register of marine Cave Species (WoRCS initiative is to create a comprehensive taxonomic and ecological database of known species from marine caves and anchialine systems worldwide and to present this as a Thematic Species Database (TSD of the World Register of marine Species (WoRMS. WoRCS will incorporate ecological data (e.g., type of environment, salinity regimes, and cave zone as well as geographical information on the distribution of species in cave and anchialine environments. Biodiversity data will be progressively assembled from individual database sources at regional, national or local levels, as well as from literature sources (estimate: >20,000 existing records of cave-dwelling species scattered in several databases. Information will be organized in the WoRCS database following a standard glossary based on existing terminology. Cave-related information will be managed by the WoRCS thematic editors with all data dynamically linked to WoRMS and its team of taxonomic editors. In order to mobilize data into global biogeographic databases, a Gazetteer of the Marine and Anchialine Caves of the World will be established. The presence records of species could be eventually georeferenced for submission to the Ocean Biogeographic Information System (OBIS and constitute an important dataset for biogeographical and

Electrostatic dominoes: long distance propagation of mutational effects in photosynthetic reaction centers of Rhodobacter capsulatus.

Science.gov (United States)

Sebban, P; Maróti, P; Schiffer, M; Hanson, D K

1995-07-04

Two point mutants from the purple bacterium Rhodobacter capsulatus, both modified in the M protein of the photosynthetic reaction center, have been studied by flash-induced absorbance spectroscopy. These strains carry either the M231Arg --> Leu or M43ASN --> Asp mutations, which are located 9 and 15 A, respectively, from the terminal electron acceptor QB. In the wild-type Rb. sphaeroides structure, M231Arg is involved in a conserved salt bridge with H125Glu and H232Glu and M43Asn is located among several polar residues that form or surround the QB binding site. These substitutions were originally uncovered in phenotypic revertants isolated from the photosynthetically incompetent L212Glu-L213Asp --> Ala-Ala site-specific double mutant. As second-site suppressor mutations, they have been shown to restore the proton transfer function that is interrupted in the L212Ala-L213Ala double mutant. The electrostatic effects that are induced in reaction centers by the M231Arg --> Leu and M43Asn --> Asp substitutions are roughly the same in either the double-mutant or wild-type backgrounds. In a reaction center that is otherwise wild type in sequence, they decrease the free energy gap between the QA- and QB- states by 24 +/- 5 and 45 +/- 5 meV, respectively. The pH dependences of K2, the QA-QB QAQB- equilibrium constant, are altered in reaction centers that carry either of these substitutions, revealing differences in the pKas of titratable groups compared to the wild type.(ABSTRACT TRUNCATED AT 250 WORDS)

Major Tom to Ground Control: How Lipoproteins Communicate Extracytoplasmic Stress to the Decision Center of the Cell.

Science.gov (United States)

Laloux, Géraldine; Collet, Jean-François

2017-11-01

The envelope of bacteria is a complex multilayered shield that ensures multiple essential functions, including protecting the cell from external assaults. Hence, bacterial cells have evolved intricate mechanisms called envelope stress response systems (ESRS) to monitor all kinds of perturbations affecting the integrity of their envelope and to mount an appropriate response to contain or repair the damage. In the model bacterium Escherichia coli , several ESRS are built around a two-component system, in which envelope stress triggers a phosphotransfer between a sensor protein in the inner membrane of the envelope and a response regulator in the cytoplasm. In this review, we focus on two major ESRS in E. coli , the Rcs and Cpx pathways, in which additional proteins not directly involved in the phosphotransfer modulate signal transduction. Both the Rcs and Cpx systems can be turned on by a lipoprotein anchored in the outer membrane, RcsF and NlpE, respectively, providing a molecular connection between the most exterior layer of the envelope and the ground control center in the cytoplasm. Here, we review how these two lipoproteins, which share a striking set of features while being distinct in several aspects, act as sentinels at the front line of the bacterium by sensing and transducing stress to the downstream components of the Rcs and Cpx systems. Copyright © 2017 American Society for Microbiology.

Detection of Singlet Oxygen Formation inside Photoactive Biohybrid Composite Material

Directory of Open Access Journals (Sweden)

Kata Hajdu

2017-12-01

Full Text Available Photosynthetic reaction center proteins (RCs are the most efficient light energy converter systems in nature. The first steps of the primary charge separation in photosynthesis take place in these proteins. Due to their unique properties, combining RCs with nano-structures promising applications can be predicted in optoelectronic systems. In the present work RCs purified from Rhodobacter sphaeroides purple bacteria were immobilized on multiwalled carbon nanotubes (CNTs. Carboxyl—and amine-functionalised CNTs were used, so different binding procedures, physical sorption and chemical sorption as well, could be applied as immobilization techniques. Light-induced singlet oxygen production was measured in the prepared photoactive biocomposites in water-based suspension by histidine mediated chemical trapping. Carbon nanotubes were applied under different conditions in order to understand their role in the equilibration of singlet oxygen concentration in the suspension. CNTs acted as effective quenchers of 1O2 either by physical (resonance energy transfer or by chemical (oxidation reaction and their efficiency showed dependence on the diffusion distance of 1O2.

NO PLIF Visualizations of the Orion Capsule in LENS-I

Science.gov (United States)

Combs, C.; Clemens, N.; Danehy, P. M.; Bathel, B.; Parker, R.; Wadhams, T.; Holden, M.; Kirk, B.

2013-01-01

Planar laser-induced fluorescence (PLIF) of nitric oxide (NO) was used to visualize the interaction of reaction-control-system (RCS) jet flows in the wake of a hypersonic capsule reentry vehicle. The tests were performed at the Calspan University at Buffalo Research Center's (CUBRC) LENS-I reflected shock tunnel facility. This was the first application of PLIF to study RCS jets in a large-scale pulsed hypersonic facility. The LENS-I facility allowed RCS jet flows to be studied while varying the flow enthalpy, Reynolds number, angle of attack and jet configuration. The interaction of pitch and roll jets with the flowfield was investigated. Additionally, thin film sensors were used to monitor heat transfer on the surface of the model to detect any localized heating resulting from the firing of the RCS jets. Tests were conducted with the model held at angles of attack of 18deg and 22deg. The nominal Mach number in all tests was 8, while Reynolds number based on model diameter ranged from 2.2x10(exp 6) - 1.5x10(exp 7). Images were processed using the Virtual Diagnostics Interface (ViDI) system developed at NASA Langley Research Center to provide a three-dimensional display of the experimental data.

The internalization of posterior subcapsular cataracts (PSCs) in Royal College of Surgeons (RCS) rats. II. The inter-relationship of optical quality and structure as a function of age.

Science.gov (United States)

Kuszak, J R; Al-Ghoul, K J; Novak, L A; Peterson, K L; Herbert, K L; Sivak, J G

1999-05-06

The Royal College of Surgeons (RCS) rat is an animal model for human retinal degenerative disease and posterior subcapsular cataracts (PSCs). The purpose of this study was to correlate the structure and optical quality of RCS lenses with PSCs as a function of their internalization, with normal, non-cataractous, age-matched control lenses. Correlative light (LM), scanning electron microscopic (SEM), three-dimensional computer assisted drawings (3D-CADs) and low power helium-neon laser scan analysis were used to examine the structure and function of lenses. The optical properties (average focal length variability; sharpness of focus) of RCS rat lenses are quantitatively compromised by PSCs. Correlative LM and SEM analysis of RCS lenses at various stages of PSC internalization (1.5, 3, 6, 9, 12 and 15 months of age), revealed that the sutures formed by additional fiber growth were progressively more abnormal. During PSC internalization, two to nine small suture branches were formed and arranged in modified line to multiple y configurations rather than the normal three branch y sutures. These temporal changes were also chronicled in animated 3D-CAD videos derived from lens reconstructions based on LM and SEM micrographs from the selected time points stated above. However, laser scan analysis also revealed that as the PSCs of RCS rat lenses were progressively internalized, there was a steady improvement in total sharpness of focus that reached normal levels by 12 months of age. The correlation of laser scan and structural data from specific regions of lenses revealed the following: 1. The abnormal posterior sutures of RCS rats with internalized PSCs effect a greater reduction in optical quality than normal posterior sutures of age-matched controls; 2. However, the resulting abnormal suture plane area was cumulatively similar to that of age-matched controls; 3. Thus, total optical quality was similar between RCS lenses with internalized PSCs and age-matched controls by

A single residue controls electron transfer gating in photosynthetic reaction centers

Czech Academy of Sciences Publication Activity Database

Shlyk, O.; Samish, I.; Matěnová, M.; Dulebo, A.; Poláková, H.; Kaftan, David; Scherz, A.

2017-01-01

Roč. 7, MAR 16 (2017), s. 1-13, č. článku 44580. ISSN 2045-2322 R&D Projects: GA ČR GA15-00703S; GA MŠk(CZ) LO1416 Institutional support: RVO:61388971 Keywords : BACTERIAL REACTION CENTERS * INDUCED STRUCTURAL-CHANGES * ATOMIC-FORCE MICROSCOPE Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 4.259, year: 2016

Protein sequences and redox titrations indicate that the electron acceptors in reaction centers from heliobacteria are similar to Photosystem I

Science.gov (United States)

Trost, J. T.; Brune, D. C.; Blankenship, R. E.

1992-01-01

Photosynthetic reaction centers isolated from Heliobacillus mobilis exhibit a single major protein on SDS-PAGE of 47 000 Mr. Attempts to sequence the reaction center polypeptide indicated that the N-terminus is blocked. After enzymatic and chemical cleavage, four peptide fragments were sequenced from the Heliobacillus mobilis apoprotein. Only one of these sequences showed significant specific similarity to any of the protein and deduced protein sequences in the GenBank data base. This fragment is identical with 56% of the residues, including both cysteines, found in highly conserved region that is proposed to bind iron-sulfur center Fx in the Photosystem I reaction center peptide that is the psaB gene product. The similarity to the psaA gene product in this region is 48%. Redox titrations of laser-flash-induced photobleaching with millisecond decay kinetics on isolated reaction centers from Heliobacterium gestii indicate a midpoint potential of -414 mV with n = 2 titration behavior. In membranes, the behavior is intermediate between n = 1 and n = 2, and the apparent midpoint potential is -444 mV. This is compared to the behavior in Photosystem I, where the intermediate electron acceptor A1, thought to be a phylloquinone molecule, has been proposed to undergo a double reduction at low redox potentials in the presence of viologen redox mediators. These results strongly suggest that the acceptor side electron transfer system in reaction centers from heliobacteria is indeed analogous to that found in Photosystem I. The sequence similarities indicate that the divergence of the heliobacteria from the Photosystem I line occurred before the gene duplication and subsequent divergence that lead to the heterodimeric protein core of the Photosystem I reaction center.

Serratia marcescens ShlA pore-forming toxin is responsible for early induction of autophagy in host cells and is transcriptionally regulated by RcsB.

Science.gov (United States)

Di Venanzio, Gisela; Stepanenko, Tatiana M; García Véscovi, Eleonora

2014-09-01

Serratia marcescens is a Gram-negative bacterium that thrives in a wide variety of ambient niches and interacts with an ample range of hosts. As an opportunistic human pathogen, it has increased its clinical incidence in recent years, being responsible for life-threatening nosocomial infections. S. marcescens produces numerous exoproteins with toxic effects, including the ShlA pore-forming toxin, which has been catalogued as its most potent cytotoxin. However, the regulatory mechanisms that govern ShlA expression, as well as its action toward the host, have remained unclear. We have shown that S. marcescens elicits an autophagic response in host nonphagocytic cells. In this work, we determine that the expression of ShlA is responsible for the autophagic response that is promoted prior to bacterial internalization in epithelial cells. We show that a strain unable to express ShlA is no longer able to induce this autophagic mechanism, while heterologous expression of ShlA/ShlB suffices to confer on noninvasive Escherichia coli the capacity to trigger autophagy. We also demonstrate that shlBA harbors a binding motif for the RcsB regulator in its promoter region. RcsB-dependent control of shlBA constitutes a feed-forward regulatory mechanism that allows interplay with flagellar-biogenesis regulation. At the top of the circuit, activated RcsB downregulates expression of flagella by binding to the flhDC promoter region, preventing FliA-activated transcription of shlBA. Simultaneously, RcsB interaction within the shlBA promoter represses ShlA expression. This circuit offers multiple access points to fine-tune ShlA production. These findings also strengthen the case for an RcsB role in orchestrating the expression of Serratia virulence factors. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Reduction of the In-Band RCS of Microstrip Patch Antenna by Using Offset Feeding Technique

Directory of Open Access Journals (Sweden)

Weiwei Xu

2014-01-01

Full Text Available This paper presents a method for implementing a low in-band scattering design for microstrip patch antennas based on the analysis of structural mode scattering and radiation characteristics. The antenna structure is first designed to have the lowest structural mode scattering in a desired frequency band. The operating frequency band of the antenna is then changed to coincide with that of the lowest structural mode scattering by adjusting the feed position on the antenna (offset feeding to achieve an antenna with low in-band radar cross section (RCS. In order to reduce the level of cross polarization of the antenna caused by offset feeding, symmetry feeding structures for both single patch antennas and two-patch arrays are proposed. Examples that show the efficiency of the method are given, and the results illustrate that the in-band RCS of the proposed antennas can be reduced by as much as 17 dBsm for plane waves impinging from the normal direction compared to patch antennas fed by conventional methods.

National demonstration of full reactor coolant system (RCS) chemical decontamination at Indian Point 2

Energy Technology Data Exchange (ETDEWEB)

Trovato, S.A.; Parry, J.O. [Consolidated Edison Co., New York, NY (United States)

1995-03-01

Key to the safe and efficient operation of the nation`s civilian nuclear power plants is the performance of maintenance activities within regulations and guidelines for personnel radiation exposure. However, maintenance activities, often performed in areas of relatively high radiation fields, will increase as the nation`s plant age. With the Nuclear Regulatory Commission (NRC) lowering the allowable radiation exposure to plant workers in 1994 and considering further reductions and regulations in the future, it is imperative that new techniques be developed and applied to reduce personnel exposure. Full primary system chemical decontamination technology offers the potential to be single most effective method of maintaining workers exposure {open_quotes}as low as reasonably achievable{close_quotes} (ALARA) while greatly reducing plant operation and maintenance (O&M) costs. A three-phase program underway since 1987, has as its goal to demonstrate that full RCS decontamination is a visible technology to reduce general plant radiation levels without threatening the long term reliability and operability of a plant. This paper discusses research leading to and plans for a National Demonstration of Full RCS Chemical Decontamination at Indian Point 2 nuclear generating station in 1995.

Simultaneous LC-MS/MS determination of JWH-210, RCS-4, ∆(9)-tetrahydrocannabinol, and their main metabolites in pig and human serum, whole blood, and urine for comparing pharmacokinetic data.

Science.gov (United States)

Schaefer, Nadine; Kettner, Mattias; Laschke, Matthias W; Schlote, Julia; Peters, Benjamin; Bregel, Dietmar; Menger, Michael D; Maurer, Hans H; Ewald, Andreas H; Schmidt, Peter H

2015-05-01

A series of new synthetic cannabinoids (SC) has been consumed without any toxicological testing. For example, pharmacokinetic data have to be collected from forensic toxicological case work and/or animal studies. To develop a corresponding model for assessing such data, samples of controlled pig studies with two selected SC (JWH-210, RCS-4) and, as reference, ∆(9)-tetrahydrocannabinol (THC) should be analyzed as well as those of human cases. Therefore, a method for determination of JWH-210, RCS-4, THC, and their main metabolites in pig and human serum, whole blood, and urine samples is presented. Specimens were analyzed by liquid-chromatography tandem mass spectrometry and multiple-reaction monitoring with three transitions per compound. Full validation was carried out for the pig specimens and cross-validation for the human specimens concerning precision and bias. For the pig studies, the limits of detection were between 0.05 and 0.50 ng/mL in serum and whole blood and between 0.05 and 1.0 ng/mL in urine, the lower limits of quantification between 0.25 and 1.0 ng/mL in serum and 0.50 and 2.0 ng/mL in whole blood and urine, and the intra- and interday precision values lower than 15% and bias values within ±15%. The applicability was tested with samples taken from a pharmacokinetic pilot study with pigs following intravenous administration of a mixture of 200 μg/kg body mass dose each of JWH-210, RCS-4, and THC. The cross-validation data for human serum, whole blood, and urine showed that this approach should also be suitable for human specimens, e.g., of clinical or forensic cases.

The study of gravity makeup to RCS for the loss of RHR event during mid-loop operation

International Nuclear Information System (INIS)

Oh, H. S.; Yoon, D. J.; Ha, S. J.; Lee, C. S.

2004-01-01

In case of the loss of residual heat removal system (RHR) event during mid-loop operation, one of the mitigation actions to prevent core uncovery is gravity makeup to the RCS. This study includes the mitigation actions for gravity makeup to the RCS for 3-loop nuclear power plant, minimum gravity makeup flow for prevention of core boiling and core uncovery and possible pass of gravity make up. Also, the evaluation of minimum gravity makeup to prevent core boiling and core uncovery was performed using the RELAP/MOD3.2.2beta code. The results of this study show that the minimum flow to prevent core uncovery in case of cold leg injection (about 20m 3 /hr) is too small to recover the core water level. So, our conclusion is that the minimum flow to prevent core boiling (about 170m 3 /hr) is enough to recover core water level

A Study on Temperature Distribution in the Hot Leg Pipes considering the Variation of Flow Rate in RCS

Energy Technology Data Exchange (ETDEWEB)

Cho, Hyuksu; Yi, Kunwoo; Choe, Yoonjae; Jang, Hocheol; Yune, Seokjeong; Park, Seongchan [KEPCO Engineering and Construction, Daejeon (Korea, Republic of)

2016-10-15

In this study, a computational analysis is performed to predict the deviation in the temperature distribution in the hot leg pipe according to the flow rate variation in RCS. In the hot leg pipes of Reactor Coolant System (RCS) of APR1400, four Resistance Temperature Detectors (RTDs), to obtain the average hot leg temperature, are installed at each hot leg pipe (two in the upper region and the other two in the lower region around the wall of the hot leg pipe). There is a deviation in temperature distribution in the hot leg pipe due to the sudden changes in the flow direction and area from the reactor core exit to the hot leg pipe. The non-uniform temperature distribution in the hot leg pipe can affect the measurement of the plant parameters such as the reactor power and the reactor coolant flow rate. The following conclusions are reached 1) The non-uniform temperature distribution in the core exit is sustained to some extent through the entire region of hot leg pipe. 2) The temperature ranges having a uniform pattern are 45 - 120° and 240 - 315°. The sensor positions of RTDs are located in this interval (45 - 120° and 240 - 315°) and this sensor positions of RTDs show the appropriate temperature measurement. Also, the temperature distribution shows the similar pattern without reference to the flow rate variation in RCS.

Bacterial Reaction Centers Purified with Styrene Maleic Acid Copolymer Retain Native Membrane Functional Properties and Display Enhanced Stability**

Science.gov (United States)

Swainsbury, David J K; Scheidelaar, Stefan; van Grondelle, Rienk; Killian, J Antoinette; Jones, Michael R

2014-01-01

Integral membrane proteins often present daunting challenges for biophysical characterization, a fundamental issue being how to select a surfactant that will optimally preserve the individual structure and functional properties of a given membrane protein. Bacterial reaction centers offer a rare opportunity to compare the properties of an integral membrane protein in different artificial lipid/surfactant environments with those in the native bilayer. Here, we demonstrate that reaction centers purified using a styrene maleic acid copolymer remain associated with a complement of native lipids and do not display the modified functional properties that typically result from detergent solubilization. Direct comparisons show that reaction centers are more stable in this copolymer/lipid environment than in a detergent micelle or even in the native membrane, suggesting a promising new route to exploitation of such photovoltaic integral membrane proteins in device applications. PMID:25212490

Dynamic J-R Characteristics of RCS Pipe Materials for Ulchin Unit 3/4. (Evaluation of Dynamic Strain Aging Effects)

Energy Technology Data Exchange (ETDEWEB)

Hong, Jun Hwa; Lee, Bong Sang; Yoon, Ji Hyun; Oh, Jong Myung; Kim, Jin Won [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1997-09-01

5 materials (45 1T-CT specimens) were tested to evaluate dynamic J-R characteristics of RCS Pipe Materials for Ulchin Unit 3/4 (Evaluation of Dynamic Strain Aging Effects). The tests were performed by DCPD method at 316 deg C and 25 deg C. The loading rates were 1000mm/min and 2000mm/min. The objectives of this project were to obtain the dynamic J-R curves data of ferritic steels for application of LBB to the RCS pipes of Ulchin Unit 3/4. The test results showed that all of the tested dynamic J-R curves of 5 materials were above the lower bound curve of static J-R curve of pipe materials for Ulchin Unit 3/4. 10 refs., 4 tabs., 16 figs. (author)

Analysis of specific factors causing RCS pressure boundary cracking

International Nuclear Information System (INIS)

Song, Taek-Ho; Jeong, Il-Seok

2007-01-01

As nuclear power plants become aged, pressure boundary integrity has become so important issue in domestic and foreign nuclear industry that many related research projects are on-going. KEPRI is going to embark a new research project for managing and preventing these kinds of cracks in nuclear power plants (NPPs). Many nuclear power plants experienced pressure boundary stress corrosion cracking (SCC) and shut downed because of it. In USA, V.C. Summer plant experienced reactor coolant pipe SCC near reactor outlet nozzle and Davis Vesse plant experienced reactor head crack around penetration pipe which is used to control rod drive mechanism. In this paper, RCS pressure boundary cracking cases and corrosion potential have been studied to find out what are the specific factors that have affected crack initiations in the reactor coolant pressure boundaries

Geometric phase and quantum interference in photosynthetic reaction center: Regulation of electron transfer

Energy Technology Data Exchange (ETDEWEB)

Sun, Yuming, E-mail: ymsun@ytu.edu.cn; Su, Yuehua; Dai, Zhenhong; Wang, WeiTian

2016-10-20

Photosynthesis is driven by electron transfer in reaction centers in which the functional unit is composed of several simple molecules C{sub 2}-symmetrically arranged into two branches. In view of quantum mechanism, both branches are possible pathways traversed by the transferred electron. Due to different evolution of spin state along two pathways in transmembrane electric potential (TEP), quantum state of the transferred electron at the bridged site acquires a geometric phase difference dependent on TEP, the most efficient electron transport takes place in a specific range of TEP beyond which electron transfer is dramatically suppressed. What’s more, reaction center acts like elaborately designed quantum device preparing polarized spin dependent on TEP for the transferred electron to regulate the reduction potential at bridged site. In brief, electron transfer generates the TEP, reversely, TEP modulates the efficiency of electron transfer. This may be an important approach to maintaining an appreciable pH environment in photosynthesis.

Utilizing the dynamic stark shift as a probe for dielectric relaxation in photosynthetic reaction centers during charge separation.

Science.gov (United States)

Guo, Zhi; Lin, Su; Woodbury, Neal W

2013-09-26

In photosynthetic reaction centers, the electric field generated by light-induced charge separation produces electrochromic shifts in the transitions of reaction center pigments. The extent of this Stark shift indirectly reflects the effective field strength at a particular cofactor in the complex. The dynamics of the effective field strength near the two monomeric bacteriochlorophylls (BA and BB) in purple photosynthetic bacterial reaction centers has been explored near physiological temperature by monitoring the time-dependent Stark shift during charge separation (dynamic Stark shift). This dynamic Stark shift was determined through analysis of femtosecond time-resolved absorbance change spectra recorded in wild type reaction centers and in four mutants at position M210. In both wild type and the mutants, the kinetics of the dynamic Stark shift differ from those of electron transfer, though not in the same way. In wild type, the initial electron transfer and the increase in the effective field strength near the active-side monomer bacteriochlorophyll (BA) occur in synchrony, but the two signals diverge on the time scale of electron transfer to the quinone. In contrast, when tyrosine is replaced by aspartic acid at M210, the kinetics of the BA Stark shift and the initial electron transfer differ, but transfer to the quinone coincides with the decay of the Stark shift. This is interpreted in terms of differences in the dynamics of the local dielectric environment between the mutants and the wild type. In wild type, comparison of the Stark shifts associated with BA and BB on the two quasi-symmetric halves of the reaction center structure confirm that the effective dielectric constants near these cofactors are quite different when the reaction center is in the state P(+)QA(-), as previously determined by Steffen et al. at 1.5 K (Steffen, M. A.; et al. Science 1994, 264, 810-816). However, it is not possible to determine from static, low-temperature measurments if the

The Quantitative Reasoning for College Science (QuaRCS) Assessment: Emerging Themes from 5 Years of Data

Science.gov (United States)

Follette, Katherine; Dokter, Erin; Buxner, Sanlyn

2018-01-01

The Quantitative Reasoning for College Science (QuaRCS) Assessment is a validated assessment instrument that was designed to measure changes in students' quantitative reasoning skills, attitudes toward mathematics, and ability to accurately assess their own quantitative abilities. It has been administered to more than 5,000 students at a variety of institutions at the start and end of a semester of general education college science instruction. I will begin by briefly summarizing our published work surrounding validation of the instrument and identification of underlying attitudinal factors (composite variables identified via factor analysis) that predict 50% of the variation in students' scores on the assessment. I will then discuss more recent unpublished work, including: (1) Development and validation of an abbreviated version of the assessment (The QuaRCS Light), which results in marked improvements in students' ability to maintain a high effort level throughout the assessment and has broad implications for quantitative reasoning assessments in general, and (2) Our efforts to revise the attitudinal portion of the assessment to better assess math anxiety level, another key factor in student performance on numerical assessments.

Functional LH1 antenna complexes influence electron transfer in bacterial photosynthetic reaction centers

NARCIS (Netherlands)

Visschers, R.W.; Vulto, S.I.E.; Jones, M.R.; van Grondelle, R.; Kraayenhof, R.

1999-01-01

The effect of the light harvesting 1 (LH1) antenna complex on the driving force for light-driven electron transfer in the Rhodobacter sphaeroides reaction center has been examined. Equilibrium redox titrations show that the presence of the LH1 antenna complex influences the free energy change for

Functional LH1 antenna complexes influence electron transfer in bacterial photosynthetic reaction centers.

NARCIS (Netherlands)

Visschers, R.W.; Vulto, S.I.E.; Jones, M.R.; van Grondelle, R.; Kraayenhof, R.

1999-01-01

The effect of the light harvesting 1 (LH1) antenna complex on the driving force for light-driven electron transfer in the Rhodobacter sphaeroides reaction center has been examined. Equilibrium redox titrations show that the presence of the LH1 antenna complex influences the free energy change for

Spectroscopic characterization of galaxy clusters in RCS-1: spectroscopic confirmation, redshift accuracy, and dynamical mass-richness relation

Science.gov (United States)

Gilbank, David G.; Barrientos, L. Felipe; Ellingson, Erica; Blindert, Kris; Yee, H. K. C.; Anguita, T.; Gladders, M. D.; Hall, P. B.; Hertling, G.; Infante, L.; Yan, R.; Carrasco, M.; Garcia-Vergara, Cristina; Dawson, K. S.; Lidman, C.; Morokuma, T.

2018-05-01

We present follow-up spectroscopic observations of galaxy clusters from the first Red-sequence Cluster Survey (RCS-1). This work focuses on two samples, a lower redshift sample of ˜30 clusters ranging in redshift from z ˜ 0.2-0.6 observed with multiobject spectroscopy (MOS) on 4-6.5-m class telescopes and a z ˜ 1 sample of ˜10 clusters 8-m class telescope observations. We examine the detection efficiency and redshift accuracy of the now widely used red-sequence technique for selecting clusters via overdensities of red-sequence galaxies. Using both these data and extended samples including previously published RCS-1 spectroscopy and spectroscopic redshifts from SDSS, we find that the red-sequence redshift using simple two-filter cluster photometric redshifts is accurate to σz ≈ 0.035(1 + z) in RCS-1. This accuracy can potentially be improved with better survey photometric calibration. For the lower redshift sample, ˜5 per cent of clusters show some (minor) contamination from secondary systems with the same red-sequence intruding into the measurement aperture of the original cluster. At z ˜ 1, the rate rises to ˜20 per cent. Approximately ten per cent of projections are expected to be serious, where the two components contribute significant numbers of their red-sequence galaxies to another cluster. Finally, we present a preliminary study of the mass-richness calibration using velocity dispersions to probe the dynamical masses of the clusters. We find a relation broadly consistent with that seen in the local universe from the WINGS sample at z ˜ 0.05.

Long-term preservation of retinal function in the RCS rat model of retinitis pigmentosa following lentivirus-mediated gene therapy.

Science.gov (United States)

Tschernutter, M; Schlichtenbrede, F C; Howe, S; Balaggan, K S; Munro, P M; Bainbridge, J W B; Thrasher, A J; Smith, A J; Ali, R R

2005-04-01

The Royal College of Surgeons (RCS) rat is a well-characterized model of autosomal recessive retinitis pigmentosa (RP) due to a defect in the retinal pigment epithelium (RPE). It is homozygous for a null mutation in the gene encoding , a receptor tyrosine kinase found in RPE cells, that is required for phagocytosis of shed photoreceptor outer segments. The absence of Mertk results in accumulation of outer segment debris. This subsequently leads to progressive loss of photoreceptor cells. In order to evaluate the efficacy of lentiviral-mediated gene replacement therapy in the RCS rat, we produced recombinant VSV-G pseudotyped HIV-1-based lentiviruses containing a murine Mertk cDNA driven by a spleen focus forming virus (SFFV) promoter. The vector was subretinally injected into the right eye of 10-day-old RCS rats; the left eye was left untreated as an internal control. Here, we present a detailed assessment of the duration and extent of the morphological rescue and the resulting functional benefits. We examined animals at various time points over a period of 7 months by light and electron microscopy, and electroretinography. We observed correction of the phagocytic defect, slowing of photoreceptor cell loss and preservation of retinal function for up to 7 months. This study demonstrates the potential of gene therapy approaches for the treatment of retinal degenerations caused by defects specific to the RPE and supports the use of lentiviral vectors for the treatment of such disorders.

Vasovagal reactions in whole blood donors at three REDS-II blood centers in Brazil.

OpenAIRE

Gonçalez, TT; Sabino, EC; Schlumpf, KS; Wright, DJ; Leao, S; Sampaio, D; Takecian, PL; Proietti, AB; Murphy, E; Busch, M; Custer, B; NHLBI Retrovirus Epidemiology Donor Study-II REDS-II, International Component,

2012-01-01

In Brazil little is known about adverse reactions during donation and the donor characteristics that may be associated with such events. Donors are offered snacks and fluids before donating and are required to consume a light meal after donation. For these reasons the frequency of reactions may be different than those observed in other countries.A cross-sectional study was conducted of eligible whole blood donors at three large blood centers located in Brazil between July 2007 and December 20...

In-flight measurements and RCS-predictions: A comparison on broad-side radar range profiles of a Boeing 737

NARCIS (Netherlands)

Heiden, R. van der; Ewijk, L.J. van; Groen, F.C.A.

1997-01-01

The validation of Radar Cross Section (RCS) prediction techniques against real measurements is crucial to acquire confidence in predictions when measurements are not available. In this paper we present the first results of a comparison on one dimensional images, i.e., radar range profiles. The

Electronically stimulated deep-center reactions in electron-irradiated InP: Comparison between experiment and recombination-enhancement theories

International Nuclear Information System (INIS)

Sibille, A.

1987-01-01

We present a detailed study of the recombination enhancement of several defect reactions involving the main deep centers in low-temperature electron-irradiated InP. A fairly good agreement is obtained with the Weeks-Tully-Kimerling theory for the activation energies of the enhanced process. On the other hand, a thorough investigation of a thermally and electronically stimulated defect transformation shows evidence that one major approximation (local vibrational equilibrium) fails, and that the recently proposed [H. Sumi, Phys. Rev. B 29, 4616 (1984)] mechanism of coherent recombination on deep centers is responsible for altered reaction rates at high injection levels

Nuclear Reaction and Structure Databases of the National Nuclear Data Center

International Nuclear Information System (INIS)

Pritychenko, B.; Arcilla, R.; Herman, M. W.; Oblozinsky, P.; Rochman, D.; Sonzogni, A. A.; Tuli, J. K.; Winchell, D. F.

2006-01-01

The National Nuclear Data Center (NNDC) collects, evaluates, and disseminates nuclear physics data for basic research and applied nuclear technologies. In 2004, the NNDC migrated all databases into modern relational database software, installed new generation of Linux servers and developed new Java-based Web service. This nuclear database development means much faster, more flexible and more convenient service to all users in the United States. These nuclear reaction and structure database developments as well as related Web services are briefly described

Hydrogen bonds in the vicinity of the special pair of the bacterial reaction center probed by hydrostatic high-pressure absorption spectroscopy.

Science.gov (United States)

Kangur, Liina; Jones, Michael R; Freiberg, Arvi

2017-12-01

Using the native bacteriochlorophyll a pigment cofactors as local probes, we investigated the response to external hydrostatic high pressure of reaction center membrane protein complexes from the photosynthetic bacterium Rhodobacter sphaeroides. Wild-type and engineered complexes were used with a varied number (0, 1 or 2) of hydrogen bonds that bind the reaction center primary donor bacteriochlorophyll cofactors to the surrounding protein scaffold. A pressure-induced breakage of hydrogen bonds was established for both detergent-purified and membrane-embedded reaction centers, but at rather different pressures: between 0.2 and 0.3GPa and at about 0.55GPa, respectively. The free energy change associated with the rupture of the single hydrogen bond present in wild-type reaction centers was estimated to be equal to 13-14kJ/mol. In the mutant with two symmetrical hydrogen bonds (FM197H) a single cooperative rupture of the two bonds was observed corresponding to an about twice stronger bond, rather than a sequential rupture of two individual bonds. Copyright © 2017 Elsevier B.V. All rights reserved.

Morphological and functional rescue in RCS rats after RPE cell line transplantation at a later stage of degeneration.

Science.gov (United States)

Wang, Shaomei; Lu, Bin; Girman, Sergej; Holmes, Toby; Bischoff, Nicolas; Lund, Raymond D

2008-01-01

It is well documented that grafting of cells in the subretinal space of Royal College of Surgeons (RCS) rats limits deterioration of vision and loss of photoreceptors if performed early in postnatal life. What is unclear is whether cells introduced later, when photoreceptor degeneration is already advanced, can still be effective. This possibility was examined in the present study, using the human retinal pigment epithelial cell line, ARPE-19. Dystrophic RCS rats (postnatal day [P] 60) received subretinal injection of ARPE-19 cells (2 x 10(5)/3 microL/eye). Spatial frequency was measured by recording optomotor responses at P100 and P150, and luminance threshold responses were recorded from the superior colliculus at P150. Retinas were stained with cresyl violet, retinal cell-specific markers, and a human nuclear marker. Control animals were injected with medium alone. Animals comparably treated with grafts at P21 were available for comparison. All animals were treated with immunosuppression. Later grafts preserved both spatial frequency and threshold responses over the control and delayed photoreceptor degeneration. There were two to three layers of rescued photoreceptors even at P150, compared with a scattered single layer in sham and untreated control retinas. Retinal cell marker staining showed an orderly array of the inner retinal lamination. The morphology of the second-order neurons was better preserved around the grafted area than in regions distant from graft. Sham injection had little effect in rescuing the photoreceptors. RPE cell line transplants delivered later in the course of degeneration can preserve not only the photoreceptors and inner retinal lamination but also visual function in RCS rats. However, early intervention can achieve better rescue.

Hot-Fire Testing of 100 LB(sub F) LOX/LCH4 Reaction Control Engine at Altitude Conditions

Science.gov (United States)

Marshall, William M.; Kleinhenz, Julie E.

2010-01-01

Liquid oxygen/liquid methane (LO2/LCH4 ) has recently been viewed as a potential green propulsion system for both the Altair ascent main engine (AME) and reaction control system (RCS). The Propulsion and Cryogenic Advanced Development Project (PCAD) has been tasked by NASA to develop these green propellant systems to enable safe and cost effective exploration missions. However, experience with LO2/LCH4 as a propellant combination is limited, so testing of these systems is critical to demonstrating reliable ignition and performance. A test program of a 100 lb f reaction control engine (RCE) is underway at the Altitude Combustion Stand (ACS) of the NASA Glenn Research Center, with a focus on conducting tests at altitude conditions. These tests include a unique propellant conditioning feed system (PCFS) which allows for the inlet conditions of the propellant to be varied to test warm to subcooled liquid propellant temperatures. Engine performance, including thrust, c* and vacuum specific impulse (I(sub sp,vac)) will be presented as a function of propellant temperature conditions. In general, the engine performed as expected, with higher performance at warmer propellant temperatures but better efficiency at lower propellant temperatures. Mixture ratio effects were inconclusive within the uncertainty bands of data, but qualitatively showed higher performance at lower ratios.

Determination of the thermal rate coefficient, products, and branching ratios for the reaction of O/+/ /D-2/ with N2

Science.gov (United States)

Torr, D. G.; Torr, M. R.

1980-01-01

Atmosphere Explorer-C satellite measurements are used to determine rate coefficients (RCs) for the following reactions: O(+)(D-2) + N2 yields N2(+) + O (reaction 1), O(+)(D-2) + N2 yields O(+)(S-4) + N2 (reaction 2), and O(+)(D-2) + N2 yields NO(+) + N (reaction 3). Results show the RC for reaction 1 to be 1 (plus 1 or minus 0.5) x 10 to the -10th cu cm per sec, for reaction 2 to be 3 (plus 1 or minus 2) x 10 to the -11th cu cm per sec, and 3 to be less than 5.5 x 10 to the -11th cu cm per sec. It is also found that the reaction of O(+)(D-2) with N2 does not constitute a detectable source of NO(+) ions in the thermosphere.

An efficient synthesis of α-amino-δ-valerolactones by the ugi five-center three-component reaction

International Nuclear Information System (INIS)

Kim, Young Bae; Lee, Duck Hyung; Park, Soo Jung; Keum, Gyo Chang; Jang, Min Seok; Kang, Soon Bang; Kim, You Seung

2002-01-01

A novel approach to α-amino-δ-valerolactones derivatives 8 by the intramolecular Ugi five-center three-component reaction (U-5C-3CR) using the multifunctional starting material, L-pentahomoserine 5 is described

Inflight performance of the Ulysses reaction control system

Science.gov (United States)

McGarry, Andrew; Berry, William; Parker, David

1997-01-01

The Ulysses spacecraft has been exploring the heliosphere since October 1990 in a six-year polar orbit. Despite varying operational demands, the pressure-fed monopropellant hydrazine reaction control system (RCS) has experienced few problems. The observed anomalies, having minimal operational impact, include plume impingement effects, electrical power overload effects and hydrazine gas generation effects. These anomalies are presented and discussed, with emphasis on the first observation of gas in the hydrazine propellant. The relatively low gas generation rate is attributed to: the use of high purity hydrazine; the configuration of the spin-stabilized spacecraft; the extensive use of titanium alloys; and the efficiency of the thermal control of the propellant tank which maintains a temperature of 21 C.

Loss of calretinin immunoreactive fibers in subcortical visual recipient structures of the RCS dystrophic rat.

Science.gov (United States)

Vugler, Anthony A; Coffey, Peter J

2003-11-01

The retinae of dystrophic Royal College of Surgeons (RCS) rats exhibit progressive photoreceptor degeneration accompanied by pathology of ganglion cells. To date, little work has examined the consequences of retinal degeneration for central visual structures in dystrophic rats. Here, we use immunohistochemistry for calretinin (CR) to label retinal afferents in the superior colliculus (SC), lateral geniculate nucleus, and olivary pretectal nucleus of RCS rats aged between 2 and 26 months of age. Early indications of fiber loss in the medial dystrophic SC were apparent between 9 and 13 months. Quantitative methods reveal a significant reduction in the level of CR immunoreactivity in visual layers of the medial dystrophic SC at 13 months (P animals aged 19-26 months the loss of CR fibers in SC was dramatic, with well-defined patches of fiber degeneration predominating in medial aspects of the structure. This fiber degeneration in SC was accompanied by increased detection of cells immunoreactive for CR. In several animals, regions of fiber loss were also found to contain strongly parvalbumin-immunoreactive cells. Loss of CR fibers was also observed in the lateral geniculate nucleus and olivary pretectal nucleus. Patterns of fiber loss in the dystrophic SC compliment reports of ganglion cell degeneration in these animals and the response of collicular neurons to degeneration is discussed in terms of plasticity of the dystrophic visual system and properties of calcium binding proteins.

Functional type 2 photosynthetic reaction centers found in the rare bacterial phylum Gemmatimonadetes

OpenAIRE

Zeng, Yonghui; Feng, Fuying; Medová, Hana; Dean, Jason; Koblížek, Michal

2014-01-01

Photosynthesis is one of the most fundamental biological processes on Earth. To date, species capable of performing (bacterio)chlorophyll-based phototrophy have been reported in six bacterial phyla. Here we report a phototrophic bacterium belonging to the rare and understudied phylum Gemmatimonadetes. This strain, isolated from a freshwater lake in the Gobi Desert, contains fully functional photosynthetic reaction centers. Its photosynthesis genes appear to originate from an ancient horizonta...

STS-26 Discovery, Orbiter Vehicle (OV) 103, OMS pod leak repair at KSC

Science.gov (United States)

1988-01-01

At the Kennedy Space Center (KSC), Rockwell manufacturing engineering specialist Claude Willis (left) and Rockwell manufacturing supervisor George Gallagher begin installation of a 'clamshell' device in the left orbital maneuvering system (OMS) pod reaction control system (RCS) of Discovery, Orbiter Vehicle (OV) 103. Gallagher performed the OMS pod nitric acid oxidizer leak repair operation using the two newly cut access ports in the Orbiter's aft bulkhead.

Japan Nuclear Reaction Data Center (JCPRG), Faculty of Science, Hokkaido University, Steering Committee progress report

Energy Technology Data Exchange (ETDEWEB)

NONE

2007-11-15

The Japan Nuclear Reaction Data Center (JCPRG) was approved as an organisation of Faculty of Science, Hokkaido University and established on April 1, 2007. In addition to nuclear data activities carried out by JCPRG (Japan-Charged Particle Nuclear Reaction Data Group), the centre is concerned with the evaluation of nuclear reaction data in nucleosynthesis in the universe. In order efficiently to compile reaction data obtained by using radioactive ion beam, the centre signed a research contract with RIKEN Nishina Center. We are scanning 16 journals for Japanese charged-particle and photo-nuclear nuclear reaction data compilation. From April 2006 to March 2007, CPND and PhND in 45 references (453 records, 1.83 MB) have been newly compiled for NRDF. Usually new data are released at the JCPRG web site several months prior to EXFOR. Since the 2006 NRDC meeting, we have made 104 new entries and have revised or deleted 142 old entries. Intensive numerical data compilations have been done. These data were shown in tabular form in dissertations which are (partially) published in Journals. About 30 new entries were compiled from these data. We have prepared CINDA batches for CPND published in Japan every half year. Each batch covers 6 issues of each of 4 Japanese journals JPJ, PTP, NST and JNRS. Bibliographies for neutron induced reaction data have been compiled by JAEA Nuclear Data Center as before. A new web-based NRDF search and plot system on MySQL was released in July, 2007. New compilation, which has been finalized for NRDF, but not for EXFOR, can be obtained from this site. DARPE (another NRDF search and plot system written in Perl) is also available at http://www.jcprg.org/darpe/. EXFOR/ENDF (http://www.jcprg.org/exfor/) search and plot system is available. We have also developed following utilities: PENDL (http://www.jcprg.org/endf/) and RENORM (http://www.jcprg.org/renorm). We are developing a new search system of CINDA. This is an extension of EXFOR/ENDF search

Interplay between excitation kinetics and reaction-center dynamics in purple bacteria

International Nuclear Information System (INIS)

Caycedo-Soler, Felipe; RodrIguez, Ferney J; Quiroga, Luis; Johnson, Neil F

2010-01-01

Photosynthesis is arguably the fundamental process of life, since it enables energy from the Sun to enter the food chain on the Earth. It is a remarkable non-equilibrium process in which photons are converted to many-body excitations, which traverse a complex biomolecular membrane, where they are captured and fuel chemical reactions within a reaction center (RC) in order to produce nutrients. The precise nature of these dynamical processes-which lie at the interface between quantum and classical behavior and involve both noise and coordination-is still being explored. Here, we focus on a striking recent empirical finding concerning an illumination-driven transition in the biomolecular membrane architecture of the purple bacteria Rsp. photometricum. Using stochastic realizations to describe a hopping rate model for excitation transfer, we show numerically and analytically that this surprising shift in preferred architectures can be traced to the interplay between the excitation kinetics and the RC dynamics. The net effect is that the bacteria profit from efficient metabolism at low illumination intensities while using dissipation to avoid an oversupply of energy at high illumination intensities.

Energetic change of the primary quinone in photosynthetic reaction center. Mutation, delayed fluorescence and model calculations (Theses of the Ph.D. dissertation)

International Nuclear Information System (INIS)

Rinyu, L.

2007-01-01

Complete text of publication follows. Photosynthesis is one of the basic metabolic processes of living organisms. Photosynthesizing species (bacteria, algae and higher class plants) convert the energy of light into other forms of free energy (redox potential, electro- chemical potential of ions and protons and phosphate-potential) which are directly suit- able either to cover the energy need of the vital processes of the cell or to storage. In reaction center (RC) protein of photo- synthetic bacteria, electron transfer is initiated upon light excitation from the excited bacteriochlorophyll dimer (P) to the secondary quinone (Q B ) via bacteriopheophytine (Bph) and the primary quinone (Q A ). In Rhodobacter sphaeroides purple bacteria, both quinones are ubiquinone-10, but due to the different protein environment, their electrochemical properties is highly different. Whereas Q A makes one-electron chemistry, Q B can be doubly reduced to form hydroquinone, Q B H 2 by uptake of two protons. Q B H 2 subsequently leaves the RC and is replaced by an oxidized quinone from to membrane pool. The semiquinones are important intermediates in the quinone reduction cycle of the RC. The redox midpoint potentials of the Q/Q - redox pairs (E m ) are also different: the Q A /Q A - has 60 mV more negative potential than the Q B /Q B - couple (pH 8) to make the (interquinone) electron transfer favorable. For fine tuning of the midpoint redox potentials of the quinones, the protein assures appropriate steric and electrostatic environment. The most important aim of this study was the design and production of reaction center mutants in the binding pocket of the primary quinone to investigate the effect of the amino acids of the protein and lipids of the membrane on the thermodynamics of the primary quinone. The first priority was the determination of the absolute free energy gap between the P* and the P + Q A - states in wild type and mutant reaction centers by comparison of the

Studies on the role of molybdenum on iodine transport in the RCS in nuclear severe accident conditions

International Nuclear Information System (INIS)

Grégoire, A.-C.; Kalilainen, J.; Cousin, F.; Mutelle, H.; Cantrel, L.; Auvinen, A.; Haste, T.; Sobanska, S.

2015-01-01

Highlights: • In oxidising conditions, Mo reacts with Cs and thus promotes gaseous iodine release. • In reducing conditions, CsI remains the dominant form for released iodine. • The nature of released iodine is well reproduced by the ASTEC code. - Abstract: The effect of molybdenum on iodine transport in the reactor coolant system (RCS) under PWR severe accident conditions was investigated in the framework of the EU SARNET project. Experiments were conducted at the VTT-Institute and at IRSN and simulations of the experimental results were performed with the ASTEC severe accident simulation code. As molybdenum affects caesium chemistry by formation of molybdates, it may have a significant impact on iodine transport in the RCS. Experimentally it has been shown that the formation of gaseous iodine is promoted in oxidising conditions, as caesium can be completely consumed to form caesium polymolybdates and is thus not available for reacting with gaseous iodine and leading to CsI aerosols. In reducing conditions, CsI remains the dominant form of iodine, as the amount of oxygen is not sufficient to allow formation of quantitative caesium polymolybdates. An I–Mo–Cs model has been developed and it reproduces well the experimental trends on iodine transport

Regulation of Germinal Center Reactions by B and T Cells

Directory of Open Access Journals (Sweden)

Yeonseok Chung

2013-10-01

Full Text Available Break of B cell tolerance to self-antigens results in the development of autoantibodies and, thus, leads to autoimmunity. How B cell tolerance is maintained during active germinal center (GC reactions is yet to be fully understood. Recent advances revealed several subsets of T cells and B cells that can positively or negatively regulate GC B cell responses in vivo. IL-21-producing CXCR5+ CD4+ T cells comprise a distinct lineage of helper T cells—termed follicular helper T cells (TFH—that can provide help for the development of GC reactions where somatic hypermutation and affinity maturation take place. Although the function of TFH cells is beneficial in generating high affinity antibodies against infectious agents, aberrant activation of TFH cell or B cell to self-antigens results in autoimmunity. At least three subsets of immune cells have been proposed as regulatory cells that can limit such antibody-mediated autoimmunity, including follicular regulatory T cells (TFR, Qa-1 restricted CD8+ regulatory T cells (CD8+TREG, and regulatory B cells (BREG. In this review, we will discuss our current understanding of GC B cell regulation with specific emphasis on the newly identified immune cell subsets involved in this process.

Energy transfer in light-adapted photosynthetic membranes: from active to saturated photosynthesis.

Science.gov (United States)

Fassioli, Francesca; Olaya-Castro, Alexandra; Scheuring, Simon; Sturgis, James N; Johnson, Neil F

2009-11-04

In bacterial photosynthesis light-harvesting complexes, LH2 and LH1 absorb sunlight energy and deliver it to reaction centers (RCs) with extraordinarily high efficiency. Submolecular resolution images have revealed that both the LH2:LH1 ratio, and the architecture of the photosynthetic membrane itself, adapt to light intensity. We investigate the functional implications of structural adaptations in the energy transfer performance in natural in vivo low- and high-light-adapted membrane architectures of Rhodospirillum photometricum. A model is presented to describe excitation migration across the full range of light intensities that cover states from active photosynthesis, where all RCs are available for charge separation, to saturated photosynthesis where all RCs are unavailable. Our study outlines three key findings. First, there is a critical light-energy density, below which the low-light adapted membrane is more efficient at absorbing photons and generating a charge separation at RCs, than the high-light-adapted membrane. Second, connectivity of core complexes is similar in both membranes, suggesting that, despite different growth conditions, a preferred transfer pathway is through core-core contacts. Third, there may be minimal subareas on the membrane which, containing the same LH2:LH1 ratio, behave as minimal functional units as far as excitation transfer efficiency is concerned.

Notable light-free catalytic activity for pollutant destruction over flower-like BiOI microspheres by a dual-reaction-center Fenton-like process.

Science.gov (United States)

Wang, Liang; Yan, Dengbiao; Lyu, Lai; Hu, Chun; Jiang, Ning; Zhang, Lili

2018-10-01

BiOI is widely used as photocatalysts for pollutant removal, water splitting, CO 2 reduction and organic transformation due to its excellent photoelectric properties. Here, we report for the first time that a light-free catalyst consisting of the flower-like BiOI microspheres (f-BiOI MSs) exposing (1 0 1) and (1 1 0) crystal planes prepared by a hydrothermal method in ethylene glycol environment can rapidly eliminate the refractory BPA within only ∼3 min through a Fenton-like process. The reaction activity is ∼190 times higher than that of the conventional Fenton catalyst Fe 2 O 3 . A series of characterizations and experiments reveal the formation of the dual reaction centers on f-BiOI MSs. The electron-rich O centers efficiently reduce H 2 O 2 to OH, while the electron-poor oxygen vacancies capture electrons from the adsorbed pollutants and divert them to the electron-rich area during the Fenton-like reactions. By these processes, pollutants are degraded and mineralized quickly in a wide pH range. Our findings address the problems of the classical Fenton reaction and are useful for the development of efficient Fenton-like catalysts through constructing dual reaction centers. Copyright © 2018 Elsevier Inc. All rights reserved.

On the nature of organic and inorganic centers that bifurcate electrons, coupling exergonic and endergonic oxidation-reduction reactions.

Science.gov (United States)

Peters, John W; Beratan, David N; Schut, Gerrit J; Adams, Michael W W

2018-04-19

Bifurcating electrons to couple endergonic and exergonic electron-transfer reactions has been shown to have a key role in energy conserving redox enzymes. Bifurcating enzymes require a redox center that is capable of directing electron transport along two spatially separate pathways. Research into the nature of electron bifurcating sites indicates that one of the keys is the formation of a low potential oxidation state to satisfy the energetics required of the endergonic half reaction, indicating that any redox center (organic or inorganic) that can exist in multiple oxidation states with sufficiently separated redox potentials should be capable of electron bifurcation. In this Feature Article, we explore a paradigm for bifurcating electrons down independent high and low potential pathways, and describe redox cofactors that have been demonstrated or implicated in driving this unique biochemistry.

Lon protease modulates virulence traits in Erwinia amylovora by direct monitoring of major regulators and indirectly through the Rcs and Gac-Csr regulatory systems.

Science.gov (United States)

Lee, Jae Hoon; Ancona, Veronica; Zhao, Youfu

2018-04-01

Lon, an ATP-dependent protease in bacteria, influences diverse cellular processes by degrading damaged, misfolded and short-lived regulatory proteins. In this study, we characterized the effects of lon mutation and determined the molecular mechanisms underlying Lon-mediated virulence regulation in Erwinia amylovora, an enterobacterial pathogen of apple. Erwinia amylovora depends on the type III secretion system (T3SS) and the exopolysaccharide (EPS) amylovoran to cause disease. Our results showed that mutation of the lon gene led to the overproduction of amylovoran, increased T3SS gene expression and the non-motile phenotype. Western blot analyses showed that mutation in lon directly affected the accumulation and stability of HrpS/HrpA and RcsA. Mutation in lon also indirectly influenced the expression of flhD, hrpS and csrB through the accumulation of the RcsA/RcsB proteins, which bind to the promoter of these genes. In addition, lon expression is under the control of CsrA, possibly at both the transcriptional and post-transcriptional levels. Although mutation in csrA abolished both T3SS and amylovoran production, deletion of the lon gene in the csrA mutant only rescued amylovoran production, but not T3SS. These results suggest that CsrA might positively control both T3SS and amylovoran production partly by suppressing Lon, whereas CsrA may also play a critical role in T3SS by affecting unknown targets. © 2017 BSPP AND JOHN WILEY & SONS LTD.

[On the influence of local molecular environment on the redox potential of electron transfer cofactors in bacterial photosynthetic reaction centers].

Science.gov (United States)

Krasil'nikov, P M; Noks, P P; Rubin, A B

2011-01-01

The addition of cryosolvents (glycerol, dimethylsulfoxide) to a water solution containing bacterial photosynthetic reaction centers changes the redox potential of the bacteriochlorophyll dimer, but does not affect the redox potential of the quinone primary acceptor. It has been shown that the change in redox potential can be produced by changes of the electrostatic interactions between cofactors and the local molecular environment modified by additives entered into the solution. The degree of influence of a solvent on the redox potential of various cofactors is determined by degree of availability of these cofactors for molecules of solvent, which depends on the arrangement of cofactors in the structure of reaction centers.

The evolutionary pathway from anoxygenic to oxygenic photosynthesis examined by comparison of the properties of photosystem II and bacterial reaction centers.

Science.gov (United States)

Allen, J P; Williams, J C

2011-01-01

In photosynthetic organisms, such as purple bacteria, cyanobacteria, and plants, light is captured and converted into energy to create energy-rich compounds. The primary process of energy conversion involves the transfer of electrons from an excited donor molecule to a series of electron acceptors in pigment-protein complexes. Two of these complexes, the bacterial reaction center and photosystem II, are evolutionarily related and structurally similar. However, only photosystem II is capable of performing the unique reaction of water oxidation. An understanding of the evolutionary process that lead to the development of oxygenic photosynthesis can be found by comparison of these two complexes. In this review, we summarize how insight is being gained by examination of the differences in critical functional properties of these complexes and by experimental efforts to alter pigment-protein interactions of the bacterial reaction center in order to enable it to perform reactions, such as amino acid and metal oxidation, observable in photosystem II.

Engineered Photosystem II reaction centers optimize photochemistry versus photoprotection at different solar intensities.

Science.gov (United States)

Vinyard, David J; Gimpel, Javier; Ananyev, Gennady M; Mayfield, Stephen P; Dismukes, G Charles

2014-03-12

The D1 protein of Photosystem II (PSII) provides most of the ligating amino acid residues for the Mn4CaO5 water-oxidizing complex (WOC) and half of the reaction center cofactors, and it is present as two isoforms in the cyanobacterium Synechococcus elongatus PCC 7942. These isoforms, D1:1 and D1:2, confer functional advantages for photosynthetic growth at low and high light intensities, respectively. D1:1, D1:2, and seven point mutations in the D1:2 background that are native to D1:1 were expressed in the green alga Chlamydomonas reinhardtii. We used these nine strains to show that those strains that confer a higher yield of PSII charge separation under light-limiting conditions (where charge recombination is significant) have less efficient photochemical turnover, measured in terms of both a lower WOC turnover probability and a longer WOC cycle period. Conversely, these same strains under light saturation (where charge recombination does not compete) confer a correspondingly faster O2 evolution rate and greater protection against photoinhibition. Taken together, the data clearly establish that PSII primary charge separation is a trade-off between photochemical productivity (water oxidation and plastoquinone reduction) and charge recombination (photoprotection). These trade-offs add up to a significant growth advantage for the two natural isoforms. These insights provide fundamental design principles for engineering of PSII reaction centers with optimal photochemical efficiencies for growth at low versus high light intensities.

Report compiled by Research Center for Carbonaceous Resources, Institute for Chemical Reaction Science, Tohoku University; Tohoku Daigaku Hanno Kagaku Kenkyusho tanso shigen hanno kenkyu center hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1994-04-01

The Research Center for Carbonaceous Resources was established in April 1991 for the purpose of developing a comprehensive process for converting carbonaceous resources into clean fuels or into materials equipped with advanced functions. In this report, the track records etc. of the center are introduced. Under study in the conversion process research department is the organization of a comprehensive coal conversion process which will be a combination of solvent extraction, catalytic decomposition, and catalytic gasification, whose goal is to convert coal in a clean way at high efficiency. Under study in the conversion catalyst research department are the development of a coal denitrogenation method, development of a low-temperature gasification method by use of inexpensive catalysts, synthesis of C{sub 2} hydrocarbons in a methane/carbon dioxide reaction, etc. Other endeavors under way involve the designing and development of new organic materials such as new carbon materials and a study of the foundation on which such efforts stand, that is, the study of the control of reactions between solids. Furthermore, in the study of interfacial reaction control, the contact gasification of coal, brown coal ion exchange capacity and surface conditions, carbonization of cation exchanged brown coal, etc., are being developed. (NEDO)

Improvement of quality with Nuclear Power Training Center (NTC) operator training

International Nuclear Information System (INIS)

Matsumoto, Y.

2005-01-01

Nuclear Power Training Center (NTC) was established in 1972 for PWR operator training. As the result of introduction of quality assurance management into NTC operator training, it became possible to confirm each step of systematic approach to training (SAT) process and then feedback process became clearer. Simulation models were modified based on domestic or overseas accidents cases and so training was improved using simulators closer to actual plants. Also a new multipurpose simulator with modified reactor coolant system (RCS) visual display device (RVD) and parameter-event-log (PEL) device was introduced in 2003 to provide more information so as to upgrade knowledge level of operators. (T. Tanaka)

Incidence of transfusion reactions: a multi-center study utilizing systematic active surveillance and expert adjudication

Science.gov (United States)

Hendrickson, Jeanne E.; Roubinian, Nareg H.; Chowdhury, Dhuly; Brambilla, Don; Murphy, Edward L.; Wu, Yanyun; Ness, Paul M.; Gehrie, Eric A.; Snyder, Edward L.; Hauser, R. George; Gottschall, Jerome L.; Kleinman, Steve; Kakaiya, Ram; Strauss, Ronald G.

2017-01-01

Background Prevalence estimates of serious hazards of transfusion vary widely. We hypothesized that the current reporting infrastructure in the United States fails to capture many transfusion reactions, and undertook a multi-center study utilizing active surveillance, data review, and adjudication to test this hypothesis. Study Design and Methods A retrospective record review was completed for a random sample of 17% of all inpatient transfusion episodes over 6 months at 4 academic tertiary care hospitals, with an episode defined as all blood products released to a patient in 6 hours. Data were recorded by trained clinical research nurses, and serious reactions were adjudicated by a panel of transfusion medicine experts. Results Of 4857 transfusion episodes investigated, 1.1% were associated with a serious reaction. Transfusion associated circulatory overload (TACO) was the most frequent serious reaction noted, being identified in 1% of transfusion episodes. Despite clinical notes describing a potential transfusion association in 59% of these cases, only 5.1% were reported to the transfusion service. Suspected transfusion related acute lung injury (TRALI/possible TRALI), anaphylactic, and hypotensive reactions were noted in 0.08%, 0.02%, and 0.02% of transfusion episodes. Minor reactions, including febrile non-hemolytic and allergic, were noted in 0.62% and 0.29% of transfusion episodes, with 30–50% reported to the transfusion service. Conclusion Underreporting of cardiopulmonary transfusion reactions is striking among academic, tertiary care hospitals. Complete and accurate reporting is essential to identify, define, establish pathogenesis, and mitigate/treat transfusion reactions. A better understanding of the failure to report may improve the accuracy of passive reporting systems. PMID:27460200

Purification and spectroscopic characterization of photosystem II reaction center complexes isolated with or without Triton X-100.

NARCIS (Netherlands)

Eijckelhoff, C.; van Roon, H.; Groot, M.L.; van Grondelle, R.; Dekker, J.P.

1996-01-01

The pigment composition of the isolated photosystem II reaction center complex in its most stable and pure form currently is a matter of considerable debate. In this contribution, we present a new method based on a combination of gel filtration chromatography and diode array detection to analyze the

Stereoselective synthesis of organosulfur compounds incorporating N-aromatic heterocyclic motifs and quaternary carbon centers via a sulfa-Michael triggered tandem reaction.

Science.gov (United States)

Qin, Tianyou; Cheng, Lu; Zhang, Sean Xiao-An; Liao, Weiwei

2015-06-14

A novel sulfa-Michael addition (SMA)-triggered tandem reaction was developed by combining a SMA reaction with a simultaneous rearomatization process utilizing a less reactive carbonyl group as an intramolecular electrophile partner, which provided a unique synthetic route to access various organosulfur compounds incorporating an N-aromatic heterocyclic motif and quaternary carbon centers.

Menaquinone-7 in the reaction center complex of the green sulfur bacterium Chlorobium vibrioforme functions as the electron acceptor A1

DEFF Research Database (Denmark)

Kjaer, B; Frigaard, N-U; Yang, F

1998-01-01

Photosynthetically active reaction center complexes were prepared from the green sulfur bacterium Chlorobium vibrioforme NCIMB 8327, and the content of quinones was determined by extraction and high-performance liquid chromatography. The analysis showed a stoichiometry of 1.7 molecules of menaqui......Photosynthetically active reaction center complexes were prepared from the green sulfur bacterium Chlorobium vibrioforme NCIMB 8327, and the content of quinones was determined by extraction and high-performance liquid chromatography. The analysis showed a stoichiometry of 1.7 molecules...

Spectroscopic properties of reaction center pigments in photosystem II core complexes: revision of the multimer model.

Science.gov (United States)

Raszewski, Grzegorz; Diner, Bruce A; Schlodder, Eberhard; Renger, Thomas

2008-07-01

Absorbance difference spectra associated with the light-induced formation of functional states in photosystem II core complexes from Thermosynechococcus elongatus and Synechocystis sp. PCC 6803 (e.g., P(+)Pheo(-),P(+)Q(A)(-),(3)P) are described quantitatively in the framework of exciton theory. In addition, effects are analyzed of site-directed mutations of D1-His(198), the axial ligand of the special-pair chlorophyll P(D1), and D1-Thr(179), an amino-acid residue nearest to the accessory chlorophyll Chl(D1), on the spectral properties of the reaction center pigments. Using pigment transition energies (site energies) determined previously from independent experiments on D1-D2-cytb559 complexes, good agreement between calculated and experimental spectra is obtained. The only difference in site energies of the reaction center pigments in D1-D2-cytb559 and photosystem II core complexes concerns Chl(D1). Compared to isolated reaction centers, the site energy of Chl(D1) is red-shifted by 4 nm and less inhomogeneously distributed in core complexes. The site energies cause primary electron transfer at cryogenic temperatures to be initiated by an excited state that is strongly localized on Chl(D1) rather than from a delocalized state as assumed in the previously described multimer model. This result is consistent with earlier experimental data on special-pair mutants and with our previous calculations on D1-D2-cytb559 complexes. The calculations show that at 5 K the lowest excited state of the reaction center is lower by approximately 10 nm than the low-energy exciton state of the two special-pair chlorophylls P(D1) and P(D2) which form an excitonic dimer. The experimental temperature dependence of the wild-type difference spectra can only be understood in this model if temperature-dependent site energies are assumed for Chl(D1) and P(D1), reducing the above energy gap from 10 to 6 nm upon increasing the temperature from 5 to 300 K. At physiological temperature, there are

Magnetic fringe field interference between the quadrupole and corrector magnets in the CSNS/RCS

Energy Technology Data Exchange (ETDEWEB)

Yang, Mei, E-mail: yangmei@ihep.ac.cn [Key Laboratory of Particle Acceleration Physics and Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); China Spallation Neutron Source, Institute of High Energy Physics, Chinese Academy of Sciences, Dongguan 523803,China (China); Dongguan Neutron Science Center, Dongguan 523808,China (China); Kang, Wen; Deng, Changdong [Key Laboratory of Particle Acceleration Physics and Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); China Spallation Neutron Source, Institute of High Energy Physics, Chinese Academy of Sciences, Dongguan 523803,China (China); Dongguan Neutron Science Center, Dongguan 523808,China (China); Sun, Xianjing [Key Laboratory of Particle Acceleration Physics and Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Li, Li; Wu, Xi [Key Laboratory of Particle Acceleration Physics and Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); China Spallation Neutron Source, Institute of High Energy Physics, Chinese Academy of Sciences, Dongguan 523803,China (China); Dongguan Neutron Science Center, Dongguan 523808,China (China); Gong, Lingling; Cheng, Da [Key Laboratory of Particle Acceleration Physics and Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhu, Yingshun; Chen, Fusan [Key Laboratory of Particle Acceleration Physics and Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

2017-03-01

The Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS) employs large aperture quadrupole and corrector magnets with small aspect ratios and relatively short iron to iron separations; so the fringe field interference becomes serious which results in integral field strength reduction and extra field harmonics. We have performed 3D magnetic field simulations to investigate the magnetic field interference in the magnet assemblies and made some adjustments on the magnet arrangement. The Fourier analysis is used to quantify the integral gradient reduction and field harmonic changes of the quadrupole magnets. Some magnetic field measurements are undertaken to verify the simulation results. The simulation details and the major results are presented in this paper.

Report on the consultants` meeting on technical aspects of the co-operation of nuclear reaction data centers

Energy Technology Data Exchange (ETDEWEB)

Lemmel, H D; Schwerer, O; Wienke, H [eds.

1995-10-01

The IAEA Nuclear Data Section convenes in annual intervals coordination meetings of the Network of the Nuclear Reaction Data Center. The present meeting dealt with technical matters of the nuclear data compilation and exchange by means of the jointly operated computerized systems CINDA, EXFOR, ENDF and others. Refs, figs and tabs.

Report on the consultants' meeting on technical aspects of the co-operation of nuclear reaction data centers

International Nuclear Information System (INIS)

Lemmel, H.D.; Schwerer, O.; Wienke, H.

1995-10-01

The IAEA Nuclear Data Section convenes in annual intervals coordination meetings of the Network of the Nuclear Reaction Data Center. The present meeting dealt with technical matters of the nuclear data compilation and exchange by means of the jointly operated computerized systems CINDA, EXFOR, ENDF and others. Refs, figs and tabs

Glial reaction in visual centers upon whole-body combined irradiation with microwaves and x-radiation

International Nuclear Information System (INIS)

Logvinov, S.V.

1989-01-01

A single whole-body preirradiation with thermogenous microwaves modifies the dynamics of the glial reactions of visual centers of ginea pigs induced by median lethal X-radiation doses. A combination of the two factors products the synergistic effect, estimated by the degree of alteration of astrocytes and oligodendroglyocytes at early times after exposure, leads to early activation of microglia, and reduces radiation-induced alterations in glia at later times (25-60 days)

Density functional theoretical study on the C-F and C-O oxidative addition reaction at an AI center

Energy Technology Data Exchange (ETDEWEB)

Kim, Yong Seong [Dept. of Science Education, Kyungnam University, Masan (Korea, Republic of); Cho, Hyun; Hwang, Sungu [Dept. of Nanomechatronics Engineering, Pusan National University, Miryang (Korea, Republic of)

2017-02-15

In this study, B3LYP/LACVP** level calculations were chosen because the level of theory was applied successfully to calculations of the thermodynamic and kinetic features of the oxidative addition reactions of alkyl and aryl halides to pincer-type complexes. This study examined the effects of the substituents on the phenyl rings of the Al(I) center. Isopropyl side chains in the phenyl rings attached to N atoms of the pincer ligand were replaced with a methyl (Me) (2) or tertiary butyl ( t Bu) group. The oxidative addition of C[BOND]F and C[BOND]O bonds to an Al (I) center was investigated computationally by DFT calculations. The geometries, thermodynamic, and kinetic features were in good agreement with the experimental data, as in previous studies on the transition metal complexes. The computational results showed that the DFT calculations could provide qualitative insight into the reactivity and thermodynamics of the oxidative addition reactions of C[BOND]F bonds.

Metabolic patterns of JWH-210, RCS-4, and THC in pig urine elucidated using LC-HR-MS/MS: Do they reflect patterns in humans?

Science.gov (United States)

Schaefer, Nadine; Helfer, Andreas G; Kettner, Mattias; Laschke, Matthias W; Schlote, Julia; Ewald, Andreas H; Meyer, Markus R; Menger, Michael D; Maurer, Hans H; Schmidt, Peter H

2017-04-01

The knowledge of pharmacokinetic (PK) properties of synthetic cannabinoids (SCs) is important for interpretation of analytical results found for example in intoxicated individuals. In the absence of human data from controlled studies, animal models elucidating SC PK have to be established. Pigs providing large biofluid sample volumes were tested for prediction of human PK data. In this context, the metabolic fate of two model SCs, namely 4-ethylnaphthalen-1-yl-(1-pentylindol-3-yl)methanone (JWH-210) and 2-(4-methoxyphenyl)-1-(1-pentyl-indol-3-yl)methanone (RCS-4), was elucidated in addition to Δ 9 -tetrahydrocannabinol (THC). After intravenous administration of the compounds, hourly collected pig urine was analyzed by liquid chromatography-high resolution mass spectrometry. The following pathways were observed: for JWH-210, hydroxylation at the ethyl side chain or pentyl chain and combinations of them followed by glucuronidation; for RCS-4, hydroxylation at the methoxyphenyl moiety or pentyl chain followed by glucuronidation as well as O-demethylation followed by glucuronidation or sulfation; for THC, THC glucuronidation, 11-hydroxylation, followed by carboxylation and glucuronidation. For both SCs, parent compounds could not be detected in urine in contrast to THC. These results were consistent with those obtained from human hepatocyte and/or human case studies. Urinary markers for the consumption of JWH-210 were the glucuronide of the N-hydroxypentyl metabolite (detectable for 3-4 h) and of RCS-4 the glucuronides of the N-hydroxypentyl, hydroxy-methoxyphenyl (detectable for at least 6 h), and the O-demethyl-hydroxy metabolites (detectable for 4 h). Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Kinetics of several oxygenated carbon-centered free radical reactions with NO2.

Science.gov (United States)

Rissanen, Matti P; Arppe, Suula L; Timonen, Raimo S

2013-05-16

Five oxygenated carbon-centered free radical reactions with nitrogen dioxide (NO2) have been studied in direct time-resolved measurements. Experiments were conducted in a temperature-controlled flow tube reactor coupled to a 193 nm exciplex laser photolysis and a resonance gas lamp photoionization mass spectrometer. Reactions were investigated under pseudofirst-order conditions, with the NO2 concentrations of the experiments in great excess over the initial radical concentrations ([R]0 CH3CO radical reactions with NO2 and, hence, includes the three smallest hydroxyalkyl radical species (CH2OH, CH2CH2OH, and CH3CHOH). The obtained rate coefficients are high with the temperature-dependent rate coefficients given by a formula k(T) = k300K × (T/300 K)(-n) as (in units of cm(3) molecule(-1) s(-1)): k(CH2OH + NO2) = (8.95 ± 2.70) × 10(-11) × (T/300 K)(-0.54±0.27) (T = 298-363 K), k(CH2CH2OH + NO2) = (5.99 ± 1.80) × 10(-11) × (T/300 K)(-1.49±0.45)(T = 241-363 K), k(CH3CHOH + NO2) = (7.48 ± 2.24) × 10(-11) × (T/300 K)(-1.36±0.41) (T = 266-363 K), k(CH3OCH2 + NO2) = (7.85 ± 2.36) × 10(-11) × (T/300 K)(-0.93±0.28) (T = 243-363 K), and k(CH3CO + NO2) = (2.87 ± 0.57) × 10(-11) × (T/300 K)(-2.45±0.49) (T = 241-363 K), where the uncertainties refer to the estimated overall uncertainties of the values obtained. The determined rate coefficients show negative temperature dependence with no apparent bath gas pressure dependence under the current experimental conditions (241-363 K and about 1-3 Torr helium). This behavior is typical for a radical-radical addition mechanism with no potential energy barrier above the energy of the separated reactants in the entrance channel of the reaction. Unfortunately the absence of detected product signals prevented gaining deeper insight into the reaction mechanism.

Raman lidar measurements of water vapor and aerosols during the atmospheric radiation measurement (ARM) remote clouds sensing (RCS) intensive observation period (IOP)

Energy Technology Data Exchange (ETDEWEB)

Melfi, S.H.; Starr, D.O`C.; Whiteman, D. [NASA Goddard Space Flight Center, Greenbelt, MD (United States)] [and others

1996-04-01

The first Atmospheric Radiation Measurement (ARM) remote Cloud Study (RCS) Intensive Operations Period (IOP) was held during April 1994 at the Southern Great Plains (SGP) site. This experiment was conducted to evaluate and calibrate state-of-the-art, ground based remote sensing instruments and to use the data acquired by these instruments to validate retrieval algorithms developed under the ARM program.

Orion Exploration Flight Test Reaction Control System Jet Interaction Heating Environment from Flight Data

Science.gov (United States)

White, Molly E.; Hyatt, Andrew J.

2016-01-01

The Orion Multi-Purpose Crew Vehicle (MPCV) Reaction Control System (RCS) is critical to guide the vehicle along the desired trajectory during re-­-entry. However, this system has a significant impact on the convective heating environment to the spacecraft. Heating augmentation from the jet interaction (JI) drives thermal protection system (TPS) material selection and thickness requirements for the spacecraft. This paper describes the heating environment from the RCS on the afterbody of the Orion MPCV during Orion's first flight test, Exploration Flight Test 1 (EFT-1). These jet plumes interact with the wake of the crew capsule and cause an increase in the convective heating environment. Not only is there widespread influence from the jet banks, there may also be very localized effects. The firing history during EFT-1 will be summarized to assess which jet bank interaction was measured during flight. Heating augmentation factors derived from the reconstructed flight data will be presented. Furthermore, flight instrumentation across the afterbody provides the highest spatial resolution of the region of influence of the individual jet banks of any spacecraft yet flown. This distribution of heating augmentation across the afterbody will be derived from the flight data. Additionally, trends with possible correlating parameters will be investigated to assist future designs and ground testing programs. Finally, the challenges of measuring JI, applying this data to future flights and lessons learned will be discussed.

Development of Probability Evaluation Methodology for High Pressure/Temperature Gas Induced RCS Boundary Failure and SG Creep Rupture

Energy Technology Data Exchange (ETDEWEB)

Lee, Byung Chul; Hong, Soon Joon; Lee, Jin Yong; Lee, Kyung Jin; Lee, Kuh Hyung [FNC Tech. Co., Seoul (Korea, Republic of)

2008-04-15

Existing MELCOR 1.8.5 model was improved in view of severe accident natural circulation and MELCOR 1.8.6 input model was developed and calculation sheets for detailed MELCOR 1.8.6 model were produced. Effects of natural circulation modeling were found by simulating SBO accident by comparing existing model with detailed model. Major phenomenon and system operations which affect on natural circulation by high temperature and high pressure gas were investigated and representative accident sequences for creep rupture model of RCS pipeline and SG tube were selected.

Nuclear Reaction Data File for Astrophysics (NRDF/A) in Hokkaido University Nuclear Reaction Data Center

International Nuclear Information System (INIS)

Kato, Kiyoshi; Kimura, Masaaki; Furutachi, Naoya; Makinaga, Ayano; Togashi, Tomoaki; Otuka, Naohiko

2010-01-01

The activities of the Japan Nuclear Reaction Data Centre is explained. The main task of the centre is data compilation of Japanese nuclear reaction data in collaboration of the International Network of Nuclear Reaction Data Centres. As one of recent activities, preparation of a new database (NRDF/A) and evaluation of astronuclear reaction data are reported. Collaboration in the nuclear data activities among Asian countries is proposed.

Simulation experiment on low-level RF control for dual-harmonic acceleration at CSNS RCS

International Nuclear Information System (INIS)

Shen Sirong; Li Xiao; Zhang Chunlin; Sun Hong; Tang Jingyu

2013-01-01

The design and test of the low-level RF (LLRF) control system for the dual-harmonic acceleration at the rapid cycling synchrotron (RCS) of China Spallation Neutron Source (CSNS) at phase Ⅰ is introduced. In order to implement the mode switch from the second harmonic to the fundamental during the acceleration cycle for one of the eight RF cavities, the LLRF system for the cavity has been designed differently from the others. Several technical measures such as the opening of the control loops during the mode switch and the reclosing of two tuning circuits of the RF amplifier at different moments, have been taken. The experimental results on the testing platform based on an RF prototype show good dynamic performance of the LLRF system and prove the feasibility of dual-harmonic operation. (authors)

Proton conduction within the reaction centers of Rhodobacter capsulatus: the electrostatic role of the protein.

OpenAIRE

Maróti, P; Hanson, D K; Baciou, L; Schiffer, M; Sebban, P

1994-01-01

Light-induced charge separation in the photosynthetic reaction center results in delivery of two electrons and two protons to the terminal quinone acceptor QB. In this paper, we have used flash-induced absorbance spectroscopy to study three strains that share identical amino acid sequences in the QB binding site, all of which lack the protonatable amino acids Glu-L212 and Asp-L213. These strains are the photosynthetically incompetent site-specific mutant Glu-L212/Asp-L213-->Ala-L212/Ala-L213 ...

Biophysical Network Modelling of the dLGN Circuit: Different Effects of Triadic and Axonal Inhibition on Visual Responses of Relay Cells.

Directory of Open Access Journals (Sweden)

Thomas Heiberg

2016-05-01

Full Text Available Despite its prominent placement between the retina and primary visual cortex in the early visual pathway, the role of the dorsal lateral geniculate nucleus (dLGN in molding and regulating the visual signals entering the brain is still poorly understood. A striking feature of the dLGN circuit is that relay cells (RCs and interneurons (INs form so-called triadic synapses, where an IN dendritic terminal can be simultaneously postsynaptic to a retinal ganglion cell (GC input and presynaptic to an RC dendrite, allowing for so-called triadic inhibition. Taking advantage of a recently developed biophysically detailed multicompartmental model for an IN, we here investigate putative effects of these different inhibitory actions of INs, i.e., triadic inhibition and standard axonal inhibition, on the response properties of RCs. We compute and investigate so-called area-response curves, that is, trial-averaged visual spike responses vs. spot size, for circular flashing spots in a network of RCs and INs. The model parameters are grossly tuned to give results in qualitative accordance with previous in vivo data of responses to such stimuli for cat GCs and RCs. We particularly investigate how the model ingredients affect salient response properties such as the receptive-field center size of RCs and INs, maximal responses and center-surround antagonisms. For example, while triadic inhibition not involving firing of IN action potentials was found to provide only a non-linear gain control of the conversion of input spikes to output spikes by RCs, axonal inhibition was in contrast found to substantially affect the receptive-field center size: the larger the inhibition, the more the RC center size shrinks compared to the GC providing the feedforward excitation. Thus, a possible role of the different inhibitory actions from INs to RCs in the dLGN circuit is to provide separate mechanisms for overall gain control (direct triadic inhibition and regulation of spatial

Biophysical Network Modelling of the dLGN Circuit: Different Effects of Triadic and Axonal Inhibition on Visual Responses of Relay Cells.

Science.gov (United States)

Heiberg, Thomas; Hagen, Espen; Halnes, Geir; Einevoll, Gaute T

2016-05-01

Despite its prominent placement between the retina and primary visual cortex in the early visual pathway, the role of the dorsal lateral geniculate nucleus (dLGN) in molding and regulating the visual signals entering the brain is still poorly understood. A striking feature of the dLGN circuit is that relay cells (RCs) and interneurons (INs) form so-called triadic synapses, where an IN dendritic terminal can be simultaneously postsynaptic to a retinal ganglion cell (GC) input and presynaptic to an RC dendrite, allowing for so-called triadic inhibition. Taking advantage of a recently developed biophysically detailed multicompartmental model for an IN, we here investigate putative effects of these different inhibitory actions of INs, i.e., triadic inhibition and standard axonal inhibition, on the response properties of RCs. We compute and investigate so-called area-response curves, that is, trial-averaged visual spike responses vs. spot size, for circular flashing spots in a network of RCs and INs. The model parameters are grossly tuned to give results in qualitative accordance with previous in vivo data of responses to such stimuli for cat GCs and RCs. We particularly investigate how the model ingredients affect salient response properties such as the receptive-field center size of RCs and INs, maximal responses and center-surround antagonisms. For example, while triadic inhibition not involving firing of IN action potentials was found to provide only a non-linear gain control of the conversion of input spikes to output spikes by RCs, axonal inhibition was in contrast found to substantially affect the receptive-field center size: the larger the inhibition, the more the RC center size shrinks compared to the GC providing the feedforward excitation. Thus, a possible role of the different inhibitory actions from INs to RCs in the dLGN circuit is to provide separate mechanisms for overall gain control (direct triadic inhibition) and regulation of spatial resolution

Distribution of Synthetic Cannabinoids JWH-210, RCS-4 and Δ 9-Tetrahydrocannabinol After Intravenous Administration to Pigs.

Science.gov (United States)

Schaefer, Nadine; Kettner, Mattias; Laschke, Matthias W; Schlote, Julia; Ewald, Andreas H; Menger, Michael D; Maurer, Hans H; Schmidt, Peter H

2017-01-01

Synthetic cannabinoids (SCs) have become an increasing issue in forensic toxicology. Controlled human studies evaluating pharmacokinetic data of SCs are lacking and only few animal studies have been published. Thus, an interpretation of analytical results found in intoxicated or poisoned individuals is difficult. Therefore, the distribution of two selected SCs, namely 4-ethylnaphthalen-1-yl-(1-pentylindol-3-yl)methanone (JWH-210) and 2-(4-methoxyphenyl)-1-(1- pentyl-indol-3-yl)methanone (RCS-4) as well as Δ9-tetrahydrocannabinol (THC) as reference were examined in pigs. Pigs (n = 6 per drug) received a single intravenous 200 μg/kg BW dose of JWH-210, RCS- 4, or THC. Six hours after administration, the animals were exsanguinated and relevant organs, important body fluids such as bile, and tissues such as muscle and adipose tissue, as well as the bradytrophic specimens dura and vitreous humor were collected. After hydrolysis and solid phase extraction, analysis was performed by LC-MS/MS. To overcome matrix effects of the LC-MS/MS analysis, a standard addition method was applied for quantification. The parent compounds could be detected in every analyzed specimen with the exception of THC that was not present in dura and vitreous humor. Moderate concentrations were present in brain, the site of biological effect. Metabolite concentrations were highest in tissues involved in metabolism and/or elimination Conclusions: Besides kidneys and lungs routinely analyzed in postmortem toxicology, brain, adipose, and muscle tissue could serve as alternative sources, particularly if other specimens are not available. Bile fluid is the most appropriate specimen for SCs and THC metabolites detection. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Distribution of Synthetic Cannabinoids JWH-210, RCS-4 and ∆ 9-Tetrahydrocannabinol After Intravenous Administration to Pigs

Science.gov (United States)

Schaefer, Nadine; Kettner, Mattias; Laschke, Matthias W.; Schlote, Julia; Ewald, Andreas H.; Menger, Michael D.; Maurer, Hans H.; Schmidt, Peter H.

2017-01-01

Background: Synthetic cannabinoids (SCs) have become an increasing issue in forensic toxicology. Controlled human studies evaluating pharmacokinetic data of SCs are lacking and only few animal studies have been published. Thus, an interpretation of analytical results found in intoxicated or poisoned individuals is difficult. Therefore, the distribution of two selected SCs, namely 4-ethylnaphthalen-1-yl-(1-pentylindol-3-yl)methanone (JWH-210) and 2-(4-methoxyphenyl)-1-(1-pentyl-indol-3-yl)methanone (RCS-4) as well as ∆9-tetrahydrocannabinol (THC) as reference were examined in pigs. Methods: Pigs (n = 6 per drug) received a single intravenous 200 µg/kg BW dose of JWH-210, RCS-4, or THC. Six hours after administration, the animals were exsanguinated and relevant organs, important body fluids such as bile, and tissues such as muscle and adipose tissue, as well as the bradytrophic specimens dura and vitreous humor were collected. After hydrolysis and solid phase extraction, analysis was performed by LC-MS/MS. To overcome matrix effects of the LC-MS/MS analysis, a standard addition method was applied for quantification. Results: The parent compounds could be detected in every analyzed specimen with the exception of THC that was not present in dura and vitreous humor. Moderate concentrations were present in brain, the site of biological effect. Metabolite concentrations were highest in tissues involved in metabolism and/or elimination. Conclusions: Besides kidneys and lungs routinely analyzed in postmortem toxicology, brain, adipose, and muscle tissue could serve as alternative sources, particularly if other specimens are not available. Bile fluid is the most appropriate specimen for SCs and THC metabolites detection. PMID:27834143

Research on Radar Cross Section Measurement Based on Near-field Imaging of Cylindrical Scanning

Directory of Open Access Journals (Sweden)

Xing Shu-guang

2015-04-01

Full Text Available A new method of Radar Cross Section (RCS measurement based on near-field imaging of cylindrical scanning surface is proposed. The method is based on the core assumption that the target consists of ideal isotropic scattered centers. Three-dimensional radar scattered images are obtained by using the proposed method, and then to obtain the RCS of the target, the scattered far field is calculated by summing the fields generated by the equivalent scattered centers. Not only three dimensional radar reflectivity images but also the RCS of targets in certain three dimensional angle areas can be obtained. Compared with circular scanning that can only obtain twodimensional radar reflectivity images and RCS results in two-dimensional angle areas, cylindrical scanning can provide more information about the scattering properties of the targets. The method has strong practicability and its validity is verified by simulations.

TRIMOLECULAR REACTIONS OF URANIUM HEXAFLUORIDE WITH WATER

Energy Technology Data Exchange (ETDEWEB)

Westbrook, M.; Becnel, J.; Garrison, S.

2010-02-25

The hydrolysis reaction of uranium hexafluoride (UF{sub 6}) is a key step in the synthesis of uranium dioxide (UO{sub 2}) powder for nuclear fuels. Mechanisms for the hydrolysis reactions are studied here with density functional theory and the Stuttgart small-core scalar relativistic pseudopotential and associated basis set for uranium. The reaction of a single UF{sub 6} molecule with a water molecule in the gas phase has been previously predicted to proceed over a relatively sizeable barrier of 78.2 kJ {center_dot} mol{sup -1}, indicating this reaction is only feasible at elevated temperatures. Given the observed formation of a second morphology for the UO{sub 2} product coupled with the observations of rapid, spontaneous hydrolysis at ambient conditions, an alternate reaction pathway must exist. In the present work, two trimolecular hydrolysis mechanisms are studied with density functional theory: (1) the reaction between two UF{sub 6} molecules and one water molecule, and (2) the reaction of two water molecules with a single UF{sub 6} molecule. The predicted reaction of two UF{sub 6} molecules with one water molecule displays an interesting 'fluorine-shuttle' mechanism, a significant energy barrier of 69.0 kJ {center_dot} mol{sup -1} to the formation of UF{sub 5}OH, and an enthalpy of reaction ({Delta}H{sub 298}) of +17.9 kJ {center_dot} mol{sup -1}. The reaction of a single UF{sub 6} molecule with two water molecules displays a 'proton-shuttle' mechanism, and is more favorable, having a slightly lower computed energy barrier of 58.9 kJ {center_dot} mol{sup -1} and an exothermic enthalpy of reaction ({Delta}H{sub 298}) of -13.9 kJ {center_dot} mol{sup -1}. The exothermic nature of the overall UF{sub 6} + 2 {center_dot} H{sub 2}O trimolecular reaction and the lowering of the barrier height with respect to the bimolecular reaction are encouraging; however, the sizable energy barrier indicates further study of the UF{sub 6} hydrolysis reaction

A new pathway for transmembrane electron transfer in photosynthetic reaction centers of Rhodobacter sphaeroides not involving the excited special pair.

NARCIS (Netherlands)

van Brederode, M.E.; Jones, M.R.; van Mourik, F.; van Stokkum, I.H.M.; van Grondelle, R.

1997-01-01

It is generally accepted that electron transfer in bacterial photosynthesis is driven by the first singlet excited state of a special pair of bacteriochlorophylls (P*). We have examined the first steps of electron transfer in a mutant of the Rhodobacter sphaeroides reaction center in which charge

A new pathway for transmembrane electron transfer in photosyntetic reaction centers of Rhodobacter sphaeroides not involving the excited special pair.

NARCIS (Netherlands)

van Brederode, M.E.; Jones, M.R.; van Mourik, F.; van Stokkum, I.H.M.; van Grondelle, R.

1997-01-01

It is generally accepted that electron transfer in bacterial photosynthesis is driven by the first singlet excited state of a special pair of bacteriochlorophylls (P*). We have examined the first steps of electron transfer in a mutant of the Rhodobacter sphaeroides reaction center in which charge

Solar Sail Attitude Control System for the NASA Near Earth Asteroid Scout Mission

Science.gov (United States)

Orphee, Juan; Diedrich, Ben; Stiltner, Brandon; Becker, Chris; Heaton, Andrew

2017-01-01

An Attitude Control System (ACS) has been developed for the NASA Near Earth Asteroid (NEA) Scout mission. The NEA Scout spacecraft is a 6U cubesat with an eighty-six square meter solar sail for primary propulsion that will launch as a secondary payload on the Space Launch System (SLS) Exploration Mission 1 (EM-1) and rendezvous with a target asteroid after a two year journey, and will conduct science imagery. The spacecraft ACS consists of three major actuating subsystems: a Reaction Wheel (RW) control system, a Reaction Control System (RCS), and an Active Mass Translator (AMT) system. The reaction wheels allow fine pointing and higher rates with low mass actuators to meet the science, communication, and trajectory guidance requirements. The Momentum Management System (MMS) keeps the speed of the wheels within their operating margins using a combination of solar torque and the RCS. The AMT is used to adjust the sign and magnitude of the solar torque to manage pitch and yaw momentum. The RCS is used for initial de-tumble, performing a Trajectory Correction Maneuver (TCM), and performing momentum management about the roll axis. The NEA Scout ACS is able to meet all mission requirements including attitude hold, slews, pointing for optical navigation and pointing for science with margin and including flexible body effects. Here we discuss the challenges and solutions of meeting NEA Scout mission requirements for the ACS design, and present a novel implementation of managing the spacecraft Center of Mass (CM) to trim the solar sail disturbance torque. The ACS we have developed has an applicability to a range of potential missions and does so in a much smaller volume than is traditional for deep space missions beyond Earth.

Center of gravity estimation using a reaction board instrumented with fiber Bragg gratings

Science.gov (United States)

Oliveira, Rui; Roriz, Paulo; Marques, Manuel B.; Frazão, Orlando

2018-03-01

The purpose of the present work is to construct a reaction board based on fiber Bragg gratings (FBGs) that could be used for estimation of the 2D coordinates of the projection of center of gravity (CG) of an object. The apparatus is consisted of a rigid equilateral triangular board mounted on three supports at the vertices, two of which have cantilevers instrumented with FBGs. When an object of known weight is placed on the board, the bending strain of the cantilevers is measured by a proportional wavelength shift of the FBGs. Applying the equilibrium conditions of a rigid body and proper calibration procedures, the wavelength shift is used to estimate the vertical reaction forces and moments of force at the supports and the coordinates of the object's CG projection on the board. This method can be used on a regular basis to estimate the CG of the human body or objects with complex geometry and density distribution. An example is provided for the estimation of the CG projection coordinates of two orthopaedic femur bone models, one intact, and the other with a hip stem implant encased. The clinical implications of changing the normal CG location by means of a prosthesis have been discussed.

Cassini Spacecraft In-Flight Swap to Backup Attitude Control Thrusters

Science.gov (United States)

Bates, David M.

2010-01-01

NASA's Cassini Spacecraft, launched on October 15th, 1997 and arrived at Saturn on June 30th, 2004, is the largest and most ambitious interplanetary spacecraft in history. In order to meet the challenging attitude control and navigation requirements of the orbit profile at Saturn, Cassini is equipped with a monopropellant thruster based Reaction Control System (RCS), a bipropellant Main Engine Assembly (MEA) and a Reaction Wheel Assembly (RWA). In 2008, after 11 years of reliable service, several RCS thrusters began to show signs of end of life degradation, which led the operations team to successfully perform the swap to the backup RCS system, the details and challenges of which are described in this paper. With some modifications, it is hoped that similar techniques and design strategies could be used to benefit other spacecraft.

EXFOR Manual. Center-to-Center Exchange Format. Version 89-1

International Nuclear Information System (INIS)

McLane, V.

1989-09-01

EXFOR is the agreed exchange format for the transmission of nuclear reaction data between national and international nuclear data centers for the benefit of nuclear data users in all countries. EXFOR is a database with several million data records containing the world's experimental nuclear reaction data induced by neutrons, photons or charged particles. Data retrievals can be obtained from the IAEA Nuclear Data Section (NDS) or from one of the co-operating data centers whose names and addresses can be found inside the manual. Their contributions and co-operative efforts are gratefully acknowledged. (author). Refs

Determination of transverse phase-space and momentum error from size measurements along the 50-MeV H- RCS injection line

International Nuclear Information System (INIS)

Cho, Y.; Crosbie, E.A.; Takeda, H.

1981-01-01

The 50-MeV H - injection line for the RCS at Argonne National Laboratory has 16 quadrupole and eight bending magnets. Horizontal and vertical profiles can be obtained at 12 wire scanner positions. Size information from these profiles can be used to determine the three ellipses parameters in each plane required to describe the transverse phase space. These locations that have dispersion permit the momentum error to be used as a fourth fitting parameter. The assumed accuracy of the size measurements provides an error matrix that predicts the rms errors of the fitted parameters

The binding of quinone to the photosynthetic reaction centers: kinetics and thermodynamics of reactions occurring at the QB-site in zwitterionic and anionic liposomes.

Science.gov (United States)

Mavelli, Fabio; Trotta, Massimo; Ciriaco, Fulvio; Agostiano, Angela; Giotta, Livia; Italiano, Francesca; Milano, Francesco

2014-07-01

Liposomes represent a versatile biomimetic environment for studying the interaction between integral membrane proteins and hydrophobic ligands. In this paper, the quinone binding to the QB-site of the photosynthetic reaction centers (RC) from Rhodobacter sphaeroides has been investigated in liposomes prepared with either the zwitterionic phosphatidylcholine (PC) or the negatively charged phosphatidylglycerol (PG) to highlight the role of the different phospholipid polar heads. Quinone binding (K Q) and interquinone electron transfer (L AB) equilibrium constants in the two type of liposomes were obtained by charge recombination reaction of QB-depleted RC in the presence of increasing amounts of ubiquinone-10 over the temperature interval 6-35 °C. The kinetic of the charge recombination reactions has been fitted by numerically solving the ordinary differential equations set associated with a detailed kinetic scheme involving electron transfer reactions coupled with quinone release and uptake. The entire set of traces at each temperature was accurately fitted using the sole quinone release constants (both in a neutral and a charge separated state) as adjustable parameters. The temperature dependence of the quinone exchange rate at the QB-site was, hence, obtained. It was found that the quinone exchange regime was always fast for PC while it switched from slow to fast in PG as the temperature rose above 20 °C. A new method was introduced in this paper for the evaluation of constant K Q using the area underneath the charge recombination traces as the indicator of the amount of quinone bound to the QB-site.

Comparison of Ground Reaction Forces, Center of Pressure and Body Center of Mass Changes in the Voluntary, Semi-Voluntary and Involuntary Gait Termination in Healthy Young Men

Directory of Open Access Journals (Sweden)

behrooz teymourian

2016-03-01

Full Text Available Objective: The aim of this study was comparing the ground reaction forces, center of pressure and body center of mass changes in voluntary, semi-voluntary and involuntary gait termination in healthy young men. Methods: In this study, 12 young men performed termination of gait in three different patterns. The variable of peak antero-posterior and vertical forces in two directions at both limbs, the time to reach peak and average forces in every limb in both directions, the center of pressure displacement of medio-lateral and antero-posterior direction for each limb and the net center of pressure and the displacement of the center of mass motion in all three motion plates were recorded using motion analysis system and force plate.The repeated measurements test was used to compare three patterns of gait termination at significance level of p&le0.5. Results: The results showed a significant difference in variables of peak antero-posterior force, the time to reach peak antero-posterior force and mean antero-posterior forces of the leading limb, the peak antero-posterior force of the trialing limbs, the depth force of leading limbs, medio-lateral cop of leading limbs displacement and vertical displacement of the center of mass, among different patterns of gait termination. Conclusion: While walking, the probability of a fall or collision damage, when a sudden or unexpected stop is required, increases. Therefore, more coordination between neuromuscular systems is required.

Tight-binding model of the photosystem II reaction center: application to two-dimensional electronic spectroscopy

International Nuclear Information System (INIS)

Gelzinis, Andrius; Valkunas, Leonas; Abramavicius, Darius; Fuller, Franklin D; Ogilvie, Jennifer P; Mukamel, Shaul

2013-01-01

We propose an optimized tight-binding electron–hole model of the photosystem II (PSII) reaction center (RC). Our model incorporates two charge separation pathways and spatial correlations of both static disorder and fast fluctuations of energy levels. It captures the main experimental features observed in time-resolved two-dimensional (2D) optical spectra at 77 K: peak pattern, lineshapes and time traces. Analysis of 2D spectra kinetics reveals that specific regions of the 2D spectra of the PSII RC are sensitive to the charge transfer states. We find that the energy disorder of two peripheral chlorophylls is four times larger than the other RC pigments. (paper)

Tight-binding model of the photosystem II reaction center: application to two-dimensional electronic spectroscopy

Science.gov (United States)

Gelzinis, Andrius; Valkunas, Leonas; Fuller, Franklin D.; Ogilvie, Jennifer P.; Mukamel, Shaul; Abramavicius, Darius

2013-07-01

We propose an optimized tight-binding electron-hole model of the photosystem II (PSII) reaction center (RC). Our model incorporates two charge separation pathways and spatial correlations of both static disorder and fast fluctuations of energy levels. It captures the main experimental features observed in time-resolved two-dimensional (2D) optical spectra at 77 K: peak pattern, lineshapes and time traces. Analysis of 2D spectra kinetics reveals that specific regions of the 2D spectra of the PSII RC are sensitive to the charge transfer states. We find that the energy disorder of two peripheral chlorophylls is four times larger than the other RC pigments.

Comparison of calculated and experimental isotope edited FTIR difference spectra for purple bacterial photosynthetic reaction centers with different quinones incorporated into the QA binding site.

Directory of Open Access Journals (Sweden)

Nan eZhao

2013-08-01

Full Text Available Previously we have shown that ONIOM type (QM/MM calculations can be used to simulate isotope edited FTIR difference spectra for neutral ubiquinone in the QA binding site in Rhodobacter sphaeroides photosynthetic reaction centers. Here we considerably extend upon this previous work by calculating isotope edited FTIR difference spectra for reaction centers with a variety of unlabeled and 18O labeled foreign quinones incorporated into the QA binding site. Isotope edited spectra were calculated for reaction centers with 2,3-dimethoxy-5,6-dimethyl-1,4-benzoquinone (MQ0, 2,3,5,6-tetramethyl-1,4-benzoquinone (duroquinone, DQ, and 2,3-dimethyl-l,4-naphthoquinone (DMNQ incorporated, and compared to corresponding experimental spectra. The calculated and experimental spectra agree well, further demonstrating the utility and applicability of our ONIOM approach for calculating the vibrational properties of pigments in protein binding sites.The normal modes that contribute to the bands in the calculated spectra, their composition, frequency and intensity, and how these quantities are modified upon 18O labeling, are presented. This computed information leads to a new and more detailed understanding/interpretation of the experimental FTIR difference spectra. Hydrogen bonding to the carbonyl groups of the incorporated quinones is shown to be relatively weak. It is also shown that there is some asymmetry in hydrogen bonding, accounting for 10-13 cm-1 separation in the frequencies of the carbonyl vibrational modes of the incorporated quinones. The extent of asymmetry H-bonding could only be established by considering the spectra for various types of quinones incorporated into the QA binding site. The quinones listed above are tail-less. Spectra were also calculated for reaction centers with corresponding tail containing quinones incorporated, and it is found that replacement of the quinone methyl group by a phytyl or prenyl chain does not alter ONIOM calculated s

Human embryonic stem cell-derived cells rescue visual function in dystrophic RCS rats.

Science.gov (United States)

Lund, Raymond D; Wang, Shaomei; Klimanskaya, Irina; Holmes, Toby; Ramos-Kelsey, Rebeca; Lu, Bin; Girman, Sergej; Bischoff, N; Sauvé, Yves; Lanza, Robert

2006-01-01

Embryonic stem cells promise to provide a well-characterized and reproducible source of replacement tissue for human clinical studies. An early potential application of this technology is the use of retinal pigment epithelium (RPE) for the treatment of retinal degenerative diseases such as macular degeneration. Here we show the reproducible generation of RPE (67 passageable cultures established from 18 different hES cell lines); batches of RPE derived from NIH-approved hES cells (H9) were tested and shown capable of extensive photoreceptor rescue in an animal model of retinal disease, the Royal College of Surgeons (RCS) rat, in which photoreceptor loss is caused by a defect in the adjacent retinal pigment epithelium. Improvement in visual performance was 100% over untreated controls (spatial acuity was approximately 70% that of normal nondystrophic rats) without evidence of untoward pathology. The use of somatic cell nuclear transfer (SCNT) and/or the creation of banks of reduced complexity human leucocyte antigen (HLA) hES-RPE lines could minimize or eliminate the need for immunosuppressive drugs and/or immunomodulatory protocols.

Nuclear data services of the Nuclear Data Centers Network available at the National Nuclear Data Center

International Nuclear Information System (INIS)

McLane, V.

1997-01-01

The Nuclear Data Centers Network provides low and medium energy nuclear reaction data to users around the world. Online retrievals are available through the U.S. National Nuclear Data Center, the Nuclear Energy Agency Data Bank, and the IAEA Nuclear Data Section from these extensive bibliographic, experimental data, and evaluated data files. In addition to nuclear reaction data, the various databases also provide nuclear structure and decay data, and other information of interest to users. The WorldWideWeb sites at the National Nuclear Data Center and the NEA Data Bank provide access to some of the Centers' files. (orig.)

Magnitude and direction of the change in dipole moment associated with excitation of the primary electron donor in Rhodopseudomonas sphaeroides reaction centers

Energy Technology Data Exchange (ETDEWEB)

Lockhart, D.J.; Boxer, S.G.

1987-02-10

The magnitude and direction of the change in dipole moment, ..delta mu.., associated with the Q/sub y/ transition of the dimeric primary electron donor (special pair or P870) in Rhodopseudomonas sphaeroides reaction centers have been measured by Stark spectroscopy at 20 /sup 0/C. The magnitude of ..delta mu.. is found to be f/sup -1/ (10.3 +/- 0.7) D, where f is a correction factor for the local dielectric properties of the protein matrix. With the spherical cavity approximation and an effective local dielectric constant of 2, f = 1.2, and absolute value of ..delta mu.. is 8.6 +/- 0.6 D. Absolute value of ..delta mu.. for the Q/sub y/ transition of the special pair is approximately a factor of 3.4 and 2 greater than for the monomeric bacteriochlorophylls and bacteriopheophytins, respectively, in the reaction center. The angle between ..delta mu.. and the transition dipole moment for excitation of the first singlet electron state of the special pair was found to be 24 +/- 2/sup 0/. The measured values are combined to suggest a physical model in which the lowest excited singlet state of the special pair has substantial charge-transfer character and where charge is separated between the two monomers comprising the dimeric special pair. This leads to the hypothesis that the first charge-separated state in bacterial photosynthesis is formed directly upon photoexcitation. These data provide stringent values for comparison with theoretical calculations of the electronic structure of the chromophores in the reaction center.

Malignant mast cell tumor of the thymus in an Royal College of Surgeons (RCS) rat.

Science.gov (United States)

Terayama, Yui; Matsuura, Tetsuro; Ozaki, Kiyokazu

2017-01-01

A 152-week-old male Royal College of Surgeons (RCS) rat kept as a non-treated animal in a long-term animal study presented with a soft mass in the anterior mediastinum, which adhered to the pleura of the lung. Histopathologically, the mass mainly consisted of round to short spindle-shaped tumor cells that had infiltrated through the hyperplastic thymic tissue. The tumor cells were arranged in loose to dense sheets. Nuclei were moderate in size and round to spindle-shaped, with small nucleoli. Almost all tumor cells exhibited abundant eosinophilic cytoplasm, including eosinophilic granules of a range of sizes. The granules of tumor cells exhibited metachromasia with toluidine blue stain and were positive for c-kit and mast cell protease II. These findings indicate that the tumor described here represents a rare case of spontaneous malignant mast cell tumor with thymic epithelial hyperplasia.

Moessbauer spectroscopy on the reaction center of Rhodopseudomonas viridis

International Nuclear Information System (INIS)

Frolov, E.; Goldanskii, V.I.; Birk, A.; Parak, F.; Fritzsch, G.; Sinning, I.; Michel, H.

1992-01-01

Proteins called 'reaction centers' (RC) can be isolated from many photosynthetic bacteria. They have one non-heme iron in a quinone acceptor region. The RC of Rhodopseudomonas viridis contains an additional tightly bound tetra-heme cytochrome c subunit. The electronic configuration of both cytochrome and the non-heme iron has been studied in the crystallized protein by Moessbauer spectroscopy at different redox potentials, pH-values, and with an addition of o-phenanthroline. At high potentials (E h =+500 mV) all heme irons are in the low spin Fe 3+ -state, and at low potential (E h = 1 50 mV) they are low spin Fe 2+ with the same Moessbauer parameters for all hemes independent of pH. Redox titrations change the relative area of the reduced and oxidized states in agreement with other methods. The non-heme iron shows a high spin Fe 2+ configuration independent of E h and pH with parameters comparable to those of Rhodopseudomonas sphaeroides. Surprisingly, there is strong evidence for another non-heme iron species in part of the molecules with a Fe 2+ low spin configuration. Incubation with o-phenanthroline decreases the relative Fe 2+ hs-area and increases the contribution of Fe 2+ ls-area. Above 210 K the mean square displacement, 2 >, of the RC-crystals increases more than linearly with temperature. This may be correlated with the increase of the electron transfer rate and indicates that intramolecular mobility influences the functional activity of a protein. (orig.)

Chemical proprieties of the iron-quinone complex in mutated reaction centers of Rb. sphaeroides

International Nuclear Information System (INIS)

Hałas, Agnieszka; Derrien, Valerie; Sebban, Pierre; Matlak, Krzysztof; Korecki, Józef; Kruk, Jerzy; Burda, Kvĕtoslava

2012-01-01

We investigated type II bacterial photosynthetic reaction centers, which contain a quinone - iron complex (Q A -Fe-Q B ) on their acceptor side. Under physiological conditions it was observed mainly in a reduced high spin state but its low spin ferrous states were also observed. Therefore, it was suggested that it might regulate the dynamical properties of the iron–quinone complex and the protonation and deprotonation events in its neighbourhood. In order to get insight into the molecular mechanism of the NHFe low spin state formation, we preformed Mössbauer studies of a wild type of Rb. sphaeroides and its two mutated forms. Our Mössbauer measurements show that the hydrophobicity of the Q A binding site can be crucial for stabilization of the high spin ferrous state of NHFe.

Enhancement of D-T reaction rate due to D-T contact

International Nuclear Information System (INIS)

Hitoki, Shigehisa; Ogasawara, Masatada; Aono, Osamu.

1979-09-01

The reaction rate that is appropriate for magnetized nonuniform plasma is numerically calculated to investigate the enhancement of the D-T reaction rate. Spatial separation of the guiding center distributions of D and T enhances the reaction rate. Cases of several guiding center configurations are investigated. The largest enhancement is obtained, when both guiding center distributions are delta-functions which are separated by a length that corresponds to the Gamow peak energy. As compared with the case of no separation of D and T, the maximum enhancing factors obtained are 2.3 for total reaction rate and 1.6 for local reaction rate. Cases of the guiding center distributions with finite widths are also investigated. (author)

Primary reaction control system/remote manipulator system interaction with loaded arm. Space shuttle engineering and operations support

Science.gov (United States)

Taylor, E. C.; Davis, J. D.

1978-01-01

A study of the interaction between the orbiter primary reaction control system (PRCS) and the remote manipulator system (RMS) with a loaded arm is documented. This analysis was performed with the Payload Deployment and Retrieval Systems Simulation (PDRSS) program with the passive arm bending option. The passive-arm model simulates the arm as massless elastic links with locked joints. The study was divided into two parts. The first part was the evaluation of the response of the arm to step inputs (i.e. constant jet torques) about each of the orbiter body axes. The second part of the study was the evaluation of the response of the arm to minimum impulse primary RCS jet firings with both single pulse and pulse train inputs.

Momentum Management for the NASA Near Earth Asteroid Scout Solar Sail Mission

Science.gov (United States)

Heaton, Andrew; Diedrich, Benjamin L.; Orphee, Juan; Stiltner, Brandon; Becker, Christopher

2017-01-01

The Momentum Management (MM) system is described for the NASA Near Earth Asteroid Scout (NEA Scout) cubesat solar sail mission. Unlike many solar sail mission proposals that used solar torque as the primary or only attitude control system, NEA Scout uses small reaction wheels (RW) and a reaction control system (RCS) with cold gas thrusters, as described in the abstract "Solar Sail Attitude Control System for Near Earth Asteroid Scout Cubesat Mission." The reaction wheels allow fine pointing and higher rates with low mass actuators to meet the science, communication, and trajectory guidance requirements. The MM system keeps the speed of the wheels within their operating margins using a combination of solar torque and the RCS.

Modelling aerosol behavior in reactor cooling systems

International Nuclear Information System (INIS)

McDonald, B.H.

1990-01-01

This paper presents an overview of some of the areas of concern in using computer codes to model fission-product aerosol behavior in the reactor cooling system (RCS) of a water-cooled nuclear reactor during a loss-of-coolant accident. The basic physical processes that require modelling include: fission product release and aerosol formation in the reactor core, aerosol transport and deposition in the reactor core and throughout the rest of the RCS, and the interaction between aerosol transport processes and the thermalhydraulics. In addition to these basic physical processes, chemical reactions can have a large influence on the nature of the aerosol and its behavior in the RCS. The focus is on the physics and the implications of numerical methods used in the computer codes to model aerosol behavior in the RCS

Molecular modeling and computational simulation of the photosystem-II reaction center to address isoproturon resistance in Phalaris minor.

Science.gov (United States)

Singh, Durg Vijay; Agarwal, Shikha; Kesharwani, Rajesh Kumar; Misra, Krishna

2012-08-01

Isoproturon is the only herbicide that can control Phalaris minor, a competitive weed of wheat that developed resistance in 1992. Resistance against isoproturon was reported to be due to a mutation in the psbA gene that encodes the isoproturon-binding D1 protein. Previously in our laboratory, a triazole derivative of isoproturon (TDI) was synthesized and found to be active against both susceptible and resistant biotypes at 0.5 kg/ha but has shown poor specificity. In the present study, both susceptible D1((S)), resistant D1((R)) and D2 proteins of the PS-II reaction center of P. minor have been modeled and simulated, selecting the crystal structure of PS-II from Thermosynechococcus elongatus (2AXT.pdb) as template. Loop regions were refined, and the complete reaction center D1/D2 was simulated with GROMACS in lipid (1-palmitoyl-2-oleoylglycero-3-phosphoglycerol, POPG) environment along with ligands and cofactor. Both S and R models were energy minimized using steepest decent equilibrated with isotropic pressure coupling and temperature coupling using a Berendsen protocol, and subjected to 1,000 ps of MD simulation. As a result of MD simulation, the best model obtained in lipid environment had five chlorophylls, two plastoquinones, two phenophytins and a bicarbonate ion along with cofactor Fe and oxygen evolving center (OEC). The triazole derivative of isoproturon was used as lead molecule for docking. The best worked out conformation of TDI was chosen for receptor-based de novo ligand design. In silico designed molecules were screened and, as a result, only those molecules that show higher docking and binding energies in comparison to isoproturon and its triazole derivative were proposed for synthesis in order to get more potent, non-resistant and more selective TDI analogs.

Nondestructive examination of the Tropical Rainfall Measuring Mission (TRMM) reaction control subsystem (RCS) propellant tanks

Science.gov (United States)

Free, James M.

1993-01-01

This paper assesses the feasibility of using eddy current nondestructive examination to determine flaw sizes in completely assembled hydrazine propellant tanks. The study was performed by the NASA Goddard Space Flight Center for the Tropical Rainfall Measuring Mission (TRMM) project to help determine whether existing propellant tanks could meet the fracture analysis requirements of the current pressure vessel specification, MIL-STD-1522A and, therefore be used on the TRMM spacecraft. After evaluating several nondestructive test methods, eddy current testing was selected as the most promising method for determining flaw sizes on external and internal surfaces of completely assembled tanks. Tests were conducted to confirm the detection capability of the eddy current NDE, procedures were developed to inspect two candidate tanks, and the test support equipment was designed. The non-spherical tank eddy current NDE test program was terminated when the decision was made to procure new tanks for the TRMM propulsion subsystem. The information on the development phase of this test program is presented in this paper as a reference for future investigation on the subject.

Kinetics of Several Oxygen-Containing Carbon-Centered Free Radical Reactions with Nitric Oxide.

Science.gov (United States)

Rissanen, Matti P; Ihlenborg, Marvin; Pekkanen, Timo T; Timonen, Raimo S

2015-07-16

Kinetics of four carbon-centered, oxygen-containing free radical reactions with nitric oxide (NO) were investigated as a function of temperature at a few Torr pressure of helium, employing flow tube reactors coupled to a laser-photolysis/resonance-gas-discharge-lamp photoionization mass spectrometer (LP-RPIMS). Rate coefficients were directly determined from radical (R) decay signals under pseudo-first-order conditions ([R]0 ≪ [NO]). The obtained rate coefficients showed negative temperature dependences, typical for a radical-radical association process, and can be represented by the following parametrizations (all in units of cm(3) molecule(-1) s(-1)): k(CH2OH + NO) = (4.76 × 10(-21)) × (T/300 K)(15.92) × exp[50700/(RT)] (T = 266-363 K, p = 0.79-3.44 Torr); k(CH3CHOH + NO) = (1.27 × 10(-16)) × (T/300 K)(6.81) × exp[28700/(RT)] (T = 241-363 K, p = 0.52-3.43 Torr); k(CH3OCH2 + NO) = (3.58 ± 0.12) × 10(-12) × (T/300 K)(-3.17±0.14) (T = 221-363 K, p = 0.50-0.80 Torr); k(T)3 = 9.62 × 10(-11) × (T/300 K)(-5.99) × exp[-7100/(RT)] (T = 221-473 K, p = 1.41-2.95 Torr), with the uncertainties given as standard errors of the fits and the overall uncertainties estimated as ±20%. The rate of CH3OCH2 + NO reaction was measured in two density ranges due to its observed considerable pressure dependence, which was not found in the studied hydroxyalkyl reactions. In addition, the CH3CO + NO rate coefficient was determined at two temperatures resulting in k298K(CH3CO + NO) = (5.6 ± 2.8) × 10(-13) cm(3) molecule(-1) s(-1). No products were found during these experiments, reasons for which are briefly discussed.

Investigation of the kinetic mechanism of the demanganization reaction between carbon-saturated liquid iron and CaF2-CaO-SiO2-based slags

Science.gov (United States)

Duan, Sheng-chao; Li, Chuang; Guo, Han-jie; Guo, Jing; Han, Shao-wei; Yang, Wen-sheng

2018-04-01

The demanganization reaction kinetics of carbon-saturated liquid iron with an eight-component slag consisting of CaO-SiO2-MgO-FeO-MnO-Al2O3-TiO2-CaF2 was investigated at 1553, 1623, and 1673 K in this study. The rate-controlling step (RCS) for the demanganization reaction with regard to the hot metal pretreatment conditions was studied via kinetics analysis based on the fundamental equation of heterogeneous reaction kinetics. From the temperature dependence of the mass transfer coefficient of a transition-metal oxide (MnO), the apparent activation energy of the demanganization reaction was estimated to be 189.46 kJ·mol-1 in the current study, which indicated that the mass transfer of MnO in the molten slag controlled the overall rate of the demanganization reaction. The calculated apparent activation energy was slightly lower than the values reported in the literature for mass transfer in a slag phase. This difference was attributed to an increase in the "specific reaction interface" (SRI) value, either as a result of turbulence at the reaction interface or a decrease of the absolute amount of slag phase during sampling, and to the addition of calcium fluoride to the slag.

How exciton-vibrational coherences control charge separation in the photosystem II reaction center.

Science.gov (United States)

Novoderezhkin, Vladimir I; Romero, Elisabet; van Grondelle, Rienk

2015-12-14

In photosynthesis absorbed sun light produces collective excitations (excitons) that form a coherent superposition of electronic and vibrational states of the individual pigments. Two-dimensional (2D) electronic spectroscopy allows a visualization of how these coherences are involved in the primary processes of energy and charge transfer. Based on quantitative modeling we identify the exciton-vibrational coherences observed in 2D photon echo of the photosystem II reaction center (PSII-RC). We find that the vibrations resonant with the exciton splittings can modify the delocalization of the exciton states and produce additional states, thus promoting directed energy transfer and allowing a switch between the two charge separation pathways. We conclude that the coincidence of the frequencies of the most intense vibrations with the splittings within the manifold of exciton and charge-transfer states in the PSII-RC is not occurring by chance, but reflects a fundamental principle of how energy conversion in photosynthesis was optimized.

Determination of transverse phase-space and momentum error from size measurements along the 50-MeV H/sup -/ RCS injection line

International Nuclear Information System (INIS)

Cho, Y.; Crosbie, E.A.; Takeda, H.

1981-01-01

The 50-Mev H/sup -/ injection line for the RCS at Argonne National Laboratory has 16 quadrupole and eight bending magnets. Horizontal and vertical profiles can be obtained at 12 wire scanner positions. Size information from these profiles can be used to determine the three ellipses parameters in each plane required to describe the transverse phase space. Those locations that have dispersion permit the momentum error to be used as a fourth fitting parameter. The assumed accuracy of the size measurements provides an error matrix that predicts the rms errors of the fitted parameters. 3 refs

Pigment organization and their interactions in reaction centers of photosystem II: optical spectroscopy at 6 K of reaction centers with modified pheophytin composition.

Science.gov (United States)

Germano, M; Shkuropatov, A Y; Permentier, H; de Wijn, R; Hoff, A J; Shuvalov, V A; van Gorkom, H J

2001-09-25

Photosystem II reaction centers (RC) with selectively exchanged pheophytin (Pheo) molecules as described in [Germano, M., Shkuropatov, A. Ya., Permentier, H., Khatypov, R. A., Shuvalov, V. A., Hoff, A. J., and van Gorkom, H. J. (2000) Photosynth. Res. 64, 189-198] were studied by low-temperature absorption, linear and circular dichroism, and triplet-minus-singlet absorption-difference spectroscopy. The ratio of extinction coefficients epsilon(Pheo)/epsilon(Chl) for Q(Y) absorption in the RC is approximately 0.40 at 6 K and approximately 0.45 at room temperature. The presence of 2 beta-carotenes, one parallel and one perpendicular to the membrane plane, is confirmed. Absorption at 670 nm is due to the perpendicular Q(Y) transitions of the two peripheral chlorophylls (Chl) and not to either Pheo. The "core" pigments, two Pheo and four Chl absorb in the 676-685 nm range. Delocalized excited states as predicted by the "multimer model" are seen in the active branch. The inactive Pheo and the nearby Chl, however, mainly contribute localized transitions at 676 and 680 nm, respectively, although large CD changes indicate that exciton interactions are present on both branches. Replacement of the active Pheo prevents triplet formation, causes an LD increase at 676 and 681 nm, a blue-shift of 680 nm absorbance, and a bleach of the 685 nm exciton band. The triplet state is mainly localized on the Chl corresponding to B(A) in purple bacteria. Both Pheo Q(Y) transitions are oriented out of the membrane plane. Their Q(X) transitions are parallel to that plane, so that the Pheos in PSII are structurally similar to their homologues in purple bacteria.

Comments on the optical lineshape function: Application to transient hole-burned spectra of bacterial reaction centers

Energy Technology Data Exchange (ETDEWEB)

Reppert, Mike; Kell, Adam; Pruitt, Thomas [Department of Chemistry, Kansas State University, Manhattan, Kansas 66506 (United States); Jankowiak, Ryszard, E-mail: ryszard@ksu.edu [Department of Chemistry, Kansas State University, Manhattan, Kansas 66506 (United States); Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States)

2015-03-07

The vibrational spectral density is an important physical parameter needed to describe both linear and non-linear spectra of multi-chromophore systems such as photosynthetic complexes. Low-temperature techniques such as hole burning (HB) and fluorescence line narrowing are commonly used to extract the spectral density for a given electronic transition from experimental data. We report here that the lineshape function formula reported by Hayes et al. [J. Phys. Chem. 98, 7337 (1994)] in the mean-phonon approximation and frequently applied to analyzing HB data contains inconsistencies in notation, leading to essentially incorrect expressions in cases of moderate and strong electron-phonon (el-ph) coupling strengths. A corrected lineshape function L(ω) is given that retains the computational and intuitive advantages of the expression of Hayes et al. [J. Phys. Chem. 98, 7337 (1994)]. Although the corrected lineshape function could be used in modeling studies of various optical spectra, we suggest that it is better to calculate the lineshape function numerically, without introducing the mean-phonon approximation. New theoretical fits of the P870 and P960 absorption bands and frequency-dependent resonant HB spectra of Rb. sphaeroides and Rps. viridis reaction centers are provided as examples to demonstrate the importance of correct lineshape expressions. Comparison with the previously determined el-ph coupling parameters [Johnson et al., J. Phys. Chem. 94, 5849 (1990); Lyle et al., ibid. 97, 6924 (1993); Reddy et al., ibid. 97, 6934 (1993)] is also provided. The new fits lead to modified el-ph coupling strengths and different frequencies of the special pair marker mode, ω{sub sp}, for Rb. sphaeroides that could be used in the future for more advanced calculations of absorption and HB spectra obtained for various bacterial reaction centers.

Comments on the optical lineshape function: Application to transient hole-burned spectra of bacterial reaction centers

International Nuclear Information System (INIS)

Reppert, Mike; Kell, Adam; Pruitt, Thomas; Jankowiak, Ryszard

2015-01-01

The vibrational spectral density is an important physical parameter needed to describe both linear and non-linear spectra of multi-chromophore systems such as photosynthetic complexes. Low-temperature techniques such as hole burning (HB) and fluorescence line narrowing are commonly used to extract the spectral density for a given electronic transition from experimental data. We report here that the lineshape function formula reported by Hayes et al. [J. Phys. Chem. 98, 7337 (1994)] in the mean-phonon approximation and frequently applied to analyzing HB data contains inconsistencies in notation, leading to essentially incorrect expressions in cases of moderate and strong electron-phonon (el-ph) coupling strengths. A corrected lineshape function L(ω) is given that retains the computational and intuitive advantages of the expression of Hayes et al. [J. Phys. Chem. 98, 7337 (1994)]. Although the corrected lineshape function could be used in modeling studies of various optical spectra, we suggest that it is better to calculate the lineshape function numerically, without introducing the mean-phonon approximation. New theoretical fits of the P870 and P960 absorption bands and frequency-dependent resonant HB spectra of Rb. sphaeroides and Rps. viridis reaction centers are provided as examples to demonstrate the importance of correct lineshape expressions. Comparison with the previously determined el-ph coupling parameters [Johnson et al., J. Phys. Chem. 94, 5849 (1990); Lyle et al., ibid. 97, 6924 (1993); Reddy et al., ibid. 97, 6934 (1993)] is also provided. The new fits lead to modified el-ph coupling strengths and different frequencies of the special pair marker mode, ω sp , for Rb. sphaeroides that could be used in the future for more advanced calculations of absorption and HB spectra obtained for various bacterial reaction centers

Studies in the reaction dynamics of beam-gas chemiluminescent reactions

International Nuclear Information System (INIS)

Prisant, M.G.

1984-01-01

This thesis develops techniques for the analysis and interpretation of data obtained from beam-gas chemiluminescence experiments. These techniques are applied to experimental studies of atom transfer reactions of the type A + BC → AB + C. A procedure is developed for determining the product rotational alignment in the center-of-mass frame from polarization measurements of chemiluminescent atom-diatom exchange reactions under beam-gas conditions. Knowledge of a vector property of a reaction, such as product alignment, provides information on the disposition of angular momentum by a chemical reaction. Fluorescence polarization and hence product alignment are measured for two prototype reactions. The reaction of metastable calcium atoms with hydrogen-chloride gas yields highly aligned calcium-chloride product which exhibits little variation of alignment with vibrational state. The reaction of ground-state calcium with fluorine gas yields moderately aligned product which shows strong variation of alignment with vibration. A multi-surface direct-interaction model is developed to interpret product alignment and population data. The predictions of this model for the reaction of calcium with fluorine show reasonable agreement with experiment

Method for predicting enzyme-catalyzed reactions

Science.gov (United States)

Hlavacek, William S.; Unkefer, Clifford J.; Mu, Fangping; Unkefer, Pat J.

2013-03-19

The reactivity of given metabolites is assessed using selected empirical atomic properties in the potential reaction center. Metabolic reactions are represented as biotransformation rules. These rules are generalized from the patterns in reactions. These patterns are not unique to reactants but are widely distributed among metabolites. Using a metabolite database, potential substructures are identified in the metabolites for a given biotransformation. These substructures are divided into reactants or non-reactants, depending on whether they participate in the biotransformation or not. Each potential substructure is then modeled using descriptors of the topological and electronic properties of atoms in the potential reaction center; molecular properties can also be used. A Support Vector Machine (SVM) or classifier is trained to classify a potential reactant as a true or false reactant using these properties.

Evolution of direct mechanisms with incident energy from the Coulomb-barrier to relativistic energies. - Two-center effects in nucleon transfer between nuclei. - Signatures of nucleon promotion in heavy ion reactions at barrier energies

International Nuclear Information System (INIS)

Oertzen, W. von; Voit, H.; Imanishi, B.

1988-10-01

This report contains a review article considering the evolution of direct mechanisms with incident energy in heavy ion reactions and two theoretical articles concerning two-center effects in transfer reactions between heavy ions and the nucleon promotion in heavy ion reactions. See hints under the relevant topics. (HSI)

High-pressure modulation of the structure of the bacterial photochemical reaction center at physiological and cryogenic temperatures

Science.gov (United States)

Timpmann, Kõu; Kangur, Liina; Lõhmus, Ants; Freiberg, Arvi

2017-07-01

The optical absorption and fluorescence response to external high pressure of the reaction center membrane chromoprotein complex from the wild-type non-sulfur photosynthetic bacterium Rhodobacter sphaeroides was investigated using the native pigment cofactors as local molecular probes of the reaction center structure at physiological (ambient) and cryogenic (79 K) temperatures. In detergent-purified complexes at ambient temperature, abrupt blue shift and accompanied broadening of the special pair band was observed at about 265 MPa. These reversible in pressure features were assigned to a pressure-induced rupture of a lone hydrogen bond that binds the photo-chemically active L-branch primary electron donor bacteriochlorophyll cofactor to the surrounding protein scaffold. In native membrane-protected complexes the hydrogen bond rupture appeared significantly restricted and occurred close to about 500 MPa. The free energy change associated with the rupture of the special pair hydrogen bond in isolate complexes was estimated to be equal to about 12 kJ mol-1. In frozen samples at cryogenic temperatures the hydrogen bond remained apparently intact up to the maximum utilized pressure of 600 MPa. In this case, however, heterogeneous spectral response of the cofactors from the L-and M-branches was observed due to anisotropic build-up of the protein structure. While in solid phase, the special pair fluorescence as a function of pressure exactly followed the respective absorption spectrum at a constant Stokes shift, at ambient temperature, the two paths began to deviate strongly from one other at the hydrogen bond rupture pressure. This effect was tentatively interpreted by different emission properties of hydrogen-bound and hydrogen-unbound special pair exciton states.

Kinematical coincidence method in transfer reactions

Energy Technology Data Exchange (ETDEWEB)

Acosta, L.; Amorini, F. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Auditore, L. [INFN Gruppo Collegato di Messina and Dipartimento di Fisica, Università di Messina (Italy); Berceanu, I. [Institute for Physics and Nuclear Engineering, Bucharest (Romania); Cardella, G., E-mail: cardella@ct.infn.it [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Chatterjiee, M.B. [Saha Institute for Nuclear Physics, Kolkata (India); De Filippo, E. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Francalanza, L.; Gianì, R. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia, Catania (Italy); Grassi, L. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Rudjer Boskovic Institute, Zagreb (Croatia); Grzeszczuk, A. [Institut of Physics, University of Silesia, Katowice (Poland); La Guidara, E. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia, Catania (Italy); Lanzalone, G. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Facoltà di Ingegneria e Architettura, Università Kore, Enna (Italy); Lombardo, I. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Scienze Fisiche, Università Federico II and INFN Sezione di Napoli (Italy); Loria, D.; Minniti, T. [INFN Gruppo Collegato di Messina and Dipartimento di Fisica, Università di Messina (Italy); Pagano, E.V. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia, Catania (Italy); and others

2013-07-01

A new method to extract high resolution angular distributions from kinematical coincidence measurements in binary reactions is presented. Kinematics is used to extract the center of mass angular distribution from the measured energy spectrum of light particles. Results obtained in the case of {sup 10}Be+p→{sup 9}Be+d reaction measured with the CHIMERA detector are shown. An angular resolution of few degrees in the center of mass is obtained. The range of applicability of the method is discussed.

Characterization of the low-temperature triplet state of chlorophyll in photosystem II core complexes: Application of phosphorescence measurements and Fourier transform infrared spectroscopy.

Science.gov (United States)

Zabelin, Alexey A; Neverov, Konstantin V; Krasnovsky, Alexander A; Shkuropatova, Valentina A; Shuvalov, Vladimir A; Shkuropatov, Anatoly Ya

2016-06-01

Phosphorescence measurements at 77 K and light-induced FTIR difference spectroscopy at 95 K were applied to study of the triplet state of chlorophyll a ((3)Chl) in photosystem II (PSII) core complexes isolated from spinach. Using both methods, (3)Chl was observed in the core preparations with doubly reduced primary quinone acceptor QA. The spectral parameters of Chl phosphorescence resemble those in the isolated PSII reaction centers (RCs). The main spectral maximum and the lifetime of the phosphorescence corresponded to 955±1 nm and of 1.65±0.05 ms respectively; in the excitation spectrum, the absorption maxima of all core complex pigments (Chl, pheophytin a (Pheo), and β-carotene) were observed. The differential signal at 1667(-)/1628(+)cm(-1) reflecting a downshift of the stretching frequency of the 13(1)-keto C=O group of Chl was found to dominate in the triplet-minus-singlet FTIR difference spectrum of core complexes. Based on FTIR results and literature data, it is proposed that (3)Chl is mostly localized on the accessory chlorophyll that is in triplet equilibrium with P680. Analysis of the data suggests that the Chl triplet state responsible for the phosphorescence and the FTIR difference spectrum is mainly generated due to charge recombination in the reaction center radical pair P680(+)PheoD1(-), and the energy and temporal parameters of this triplet state as well as the molecular environment and interactions of the triplet-bearing Chl molecule are similar in the PSII core complexes and isolated PSII RCs. Copyright © 2016 Elsevier B.V. All rights reserved.

Coil-On-Plug Ignition for LOX/Methane Liquid Rocket Engines in Thermal Vacuum Environments

Science.gov (United States)

Melcher, John C.; Atwell, Matthew J.; Morehead, Robert L.; Hurlbert, Eric A.; Bugarin, Luz; Chaidez, Mariana

2017-01-01

A coil-on-plug ignition system has been developed and tested for Liquid Oxygen (LOX) / liquid methane rocket engines operating in thermal vacuum conditions. The igniters were developed and tested as part of the Integrated Cryogenic Propulsion Test Article (ICPTA), previously tested as part of the Project Morpheus test vehicle. The ICPTA uses an integrated, pressure-fed, cryogenic LOX/methane propulsion system including a reaction control system (RCS) and a main engine. The ICPTA was tested at NASA Glenn Research Center's Plum Brook Station in the Spacecraft Propulsion Research Facility (B-2) under vacuum and thermal vacuum conditions. In order to successfully demonstrate ignition reliability in the vacuum conditions and eliminate corona discharge issues, a coil-on-plug ignition system has been developed. The ICPTA uses spark-plug ignition for both the main engine igniter and the RCS. The coil-on-plug configuration eliminates the conventional high-voltage spark plug cable by combining the coil and the spark-plug into a single component. Prior to ICPTA testing at Plum Brook, component-level reaction control engine (RCE) and main engine igniter testing was conducted at NASA Johnson Space Center (JSC), which demonstrated successful hot-fire ignition using the coil-on-plug from sea-level ambient conditions down to 10(exp.-2) torr. Integrated vehicle hot-fire testing at JSC demonstrated electrical and command/data system performance. Lastly, Plum Brook testing demonstrated successful ignitions at simulated altitude conditions at 30 torr and cold thermal-vacuum conditions at 6 torr. The test campaign successfully proved that coil-on-plug technology will enable integrated LOX/methane propulsion systems in future spacecraft.

Coil-On-Plug Ignition for Oxygen/Methane Liquid Rocket Engines in Thermal-Vacuum Environments

Science.gov (United States)

Melcher, John C.; Atwell, Matthew J.; Morehead, Robert L.; Hurlbert, Eric A.; Bugarin, Luz; Chaidez, Mariana

2017-01-01

A coil-on-plug ignition system has been developed and tested for Liquid Oxygen (LOX)/liquid methane (LCH4) rocket engines operating in thermal vacuum conditions. The igniters were developed and tested as part of the Integrated Cryogenic Propulsion Test Article (ICPTA), previously tested as part of the Project Morpheus test vehicle. The ICPTA uses an integrated, pressure-fed, cryogenic LOX/LCH4 propulsion system including a reaction control system (RCS) and a main engine. The ICPTA was tested at NASA Glenn Research Center's Plum Brook Station in the Spacecraft Propulsion Research Facility (B-2) under vacuum and thermal vacuum conditions. A coil-on-plug ignition system has been developed to successfully demonstrate ignition reliability at these conditions while preventing corona discharge issues. The ICPTA uses spark plug ignition for both the main engine igniter and the RCS. The coil-on-plug configuration eliminates the conventional high-voltage spark plug cable by combining the coil and the spark plug into a single component. Prior to ICPTA testing at Plum Brook, component-level reaction control engine (RCE) and main engine igniter testing was conducted at NASA Johnson Space Center (JSC), which demonstrated successful hot-fire ignition using the coil-on-plug from sea-level ambient conditions down to 10(exp -2) torr. Integrated vehicle hot-fire testing at JSC demonstrated electrical and command/data system performance. Lastly, hot-fire testing at Plum Brook demonstrated successful ignitions at simulated altitude conditions at 30 torr and cold thermal-vacuum conditions at 6 torr. The test campaign successfully proved that coil-on-plug technology will enable integrated LOX/LCH4 propulsion systems in future spacecraft.

Fission product transport in the primary system, important phenomena, and code status

International Nuclear Information System (INIS)

Gieseke, J.A.; Jordan, H.; Kuhlman, M.R.

1990-01-01

The purpose of this paper is to identify important issues concerning the transport and deposition of radionuclides in the reactor coolant system (RCS) under accident conditions and to examine how such issues are being treated or should be treated by the various available computer codes. In general, the RCS is a very important section of the transport pathway along which radionuclides move and by which they are attenuated as they travel after being released from the fuel. The RCS can serve as a sink for radionuclides that may deposit from the gas and react with surfaces, or can serve as a repository for materials deposited from the gas which are then available for later release into the transporting gas stream. The RCS may also have thermal hydraulic conditions that foster aerosol growth by condensation or agglomeration, and may provide an environment in which gas phase or heterogeneous chemical reactions may occur

Applications of β-gal-III isozyme from Bacillus coagulans RCS3, in lactose hydrolysis.

Science.gov (United States)

Batra, Navneet; Singh, Jagtar; Joshi, Amit; Bhatia, Sonu

2011-12-01

Bacillus coagulans RCS3 isolated from hot water springs secreted five isozymes i.e. β-gal I-V of β-galactosidase. β-gal III isozyme was purified using DEAE cellulose and Sephadex G 100 column chromatography. Its molecular weight characterization showed a single band at 315kD in Native PAGE, while two subunits of 50.1 and 53.7 kD in SDS PAGE. β-Gal III had pH optima in the range of 6-7 and temperature optima at 65°C. It preferred nitro-aryl-β-d-galactoside as substrate having K(m) of 4.16 mM with ONPG. More than 85% and 80% hydrolysis of lactose (1-5%, w/v) was recorded within 48 h of incubation at 55°C and 50°C respectively and pH range of 6-7. About 78-86% hydrolysis of lactose in various brands of standardized milk was recorded at incubation temperature of 50°C. These results marked the applications of β-gal III in processing of milk/whey industry. Copyright © 2011 Elsevier B.V. All rights reserved.

Alumina Ceramics Vacuum Duct for the 3GeV-RCS of the J-PARC

CERN Document Server

Kinsho, Michikazu; Ogiwara, Norio; Saito, Yoshio

2005-01-01

It was success to develop alumina ceramics vacuum ducts for the 3GeV-RCS of J-PARC at JAERI. There are two types of alumina ceramics vacuum ducts needed, one being 1.5m-long duct with a circular cross section for use in the quadrupole magnet, the other being 3.5m-long and bending 15 degrees, with a race-track cross section for use in the dipole magnet. These ducts could be manufactured by joining several duct segments of 0.5-0.8 m in length by brazing. The alumina ceramics ducts have copper stripes on the outside surface of the ducts to reduce the duct impedance. One of the ends of each stripe is connected to a titanium flange by way of a capacitor so to interrupt an eddy current circuit. The copper stripes are produced by an electroforming method in which a stripe pattern formed by Mo-Mn metallization is first sintered on the exterior surface and then overlaid by PR-electroformed copper (Periodic current Reversal electroforming method). In order to reduce emission of secondary electrons when protons or elect...

The importance of a hot-sequential mechanism in triplet-state formation by charge recombination in reaction centers of bacterial photosynthesis

International Nuclear Information System (INIS)

Saito, K.; Mukai, K.; Sumi, H.

2006-01-01

In photosynthesis, pigment-excitation energies in the antenna system produced by light harvesting are transferred among antenna pigments toward the core antenna, where they are captured by the reaction center and initially fixed in the form of a charge separation. Primary charge separation between an oxidized special pair (P + ) and a reduced bacteriopheohytin (H - ) is occasionally intervened by recombination, and a spin-triplet state ( 3 P*) is formed on P in the bacterial reaction center. The 3 P* state is harmful to bio-organisms, inducing the formation of the highly damaging singlet oxygen species. Therefore, understanding the 3 P*-formation mechanism is important. The 3 P* formation is mediated by a state |m> of intermediate charge separation between P and the accessory chlorophyll, which is located between P and H. It will be shown theoretically in the present work that at room temperature, not only the mechanism of superexchange by quantum-mechanical virtual mediation at |m>, but also a hot-sequential mechanism contributes to the mediation. In the latter, although |m> is produced as a real state, the final state 3 P* is quickly formed during thermalization of phonons in the protein matrix in |m>. In the former, the final state is formed more quickly before dephasing-thermalization of phonons in |m>. 3 P* is unistep formed from the charge-separated state in the both mechanisms

EXFOR Basics. A short guide to the neutron reaction data exchange format

International Nuclear Information System (INIS)

McLane, V.; NUCLEAR DATA CENTER NETWORK

2000-01-01

This manual is intended as a guide to users of nuclear reaction data compiled in the EXFOR format, and is not intended as a complete guide to the EXFOR System. EXFOR is the exchange format designed to allow transmission of nuclear reaction data between the Nuclear Reaction Data Centers. In addition to storing the data and its' bibliographic information, experimental information is also compiled. The status (e.g., the source of the data) and history (e.g., date of last update) of the data set is also included. EXFOR is designed for flexibility in order to meet the diverse needs of the nuclear reaction data centers. It was originally conceived for the exchange of neutron data and was developed through discussions among personnel from centers situated in Saclay, Vienna, Livermore and Brookhaven. It was accepted as the official exchange format of the neutron data centers at Saclay, Vienna, Brookhaven and Obninsk, at a meeting held in November 1969.3 As a result of two meetings held in 1975 and 1976 and attended by several charged-particle data centers, the format was further developed and adapted to cover all nuclear reaction data. The exchange format should not be confused with a center-to-user format. Although users may obtain data from the centers in the EXFOR format, other center-to-user formats have been developed to meet the needs of the users within each center's own sphere of responsibility. The EXFOR format, as outlined, allows a large variety of numerical data tables with explanatory and bibliographic information to be transmitted in a format: l that is machine-readable (for checking and indicating possible errors); l that can be read by personnel (for passing judgment on and correcting errors). The data presently included in the EXFOR exchange file include: a complete compilation of experimental neutron-induced reaction data, a selected compilation of charged-particle-induced reaction data, a selected compilation of photon-induced reaction data

Transparent Gap Filler Solution over a DVB-RCS2 Satellite Platform in a Railway Scenario: Performance Evaluation Study

Directory of Open Access Journals (Sweden)

Peppino Fazio

2015-01-01

Full Text Available In this work, a performance study of a system equipped with a transparent Gap Filler solution in a DVB-RCS2 satellite platform has been provided. In particular, a simulation model based on a 3-state Markov chain, overcoming the blockage status through the introduction of a transparent Gap Filler (using devices on both tunnel sides has been implemented. The handover time, due to switching mechanism between satellite and Gap Filler, has been taken into account. As reference scenario, the railway market has been considered, which is characterized by a N-LOS condition, due to service disruptions caused by tunnels, vegetation and buildings. The system performance, in terms of end-to-end delay, queue size and packet loss percentage, have been evaluated, in order to prove the goodness of communications in a real railroad path.

Bibliographic index to photonuclear reaction data (1955--1992)

Energy Technology Data Exchange (ETDEWEB)

Asami, Tetsuo [Data Engineering, Inc., Yokohama (Japan); Nakagawa, Tsuneo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Dept. of Reactor Engineering

1993-10-01

Japanese Nuclear Data Committee (JNDC) has a plan to compile the evaluated data library for photon-induced nuclear reaction cross sections, and the work on the data evaluation is in progress at the present. In the evaluations for these data a bibliographic index for neutron nuclear data is required. As the bibliographic index to photonuclear reactions, several excellent compilations have been done at some research institutes in the world, and have contributed to various basic and applied researches on the photonuclear reactions. For example, there are the abstract sheets published by US National Bureau of Standards and the data index published regularly in Russia. On the other hand, the four-center network on nuclear data (US National Nuclear Data Center at Brookhaven, Russian Nuclear Data Center at Obninsk, NEA Data Bank at Paris and IAEA Nuclear Data Section at Vienna) compiles and exchanges the numerical data on photonuclear reactions as well as on neutron-induced ones, in the EXFOR format. Those numerical data are available for users. There is, however, no bibliographic index to photonuclear reactions, available for general users. Therefore, the present work to make a photonuclear reaction data index has been done urgently to contribute to the above-mentioned data evaluation. Although these data might be still incomplete and have some defects, we have decided to serve this as the first edition of our photonuclear reaction index.

Human Umbilical Cord Mesenchymal Stem Cells: Subpopulations and Their Difference in Cell Biology and Effects on Retinal Degeneration in RCS Rats.

Science.gov (United States)

Wang, L; Li, P; Tian, Y; Li, Z; Lian, C; Ou, Q; Jin, C; Gao, F; Xu, J-Y; Wang, J; Wang, F; Zhang, J; Zhang, J; Li, W; Tian, H; Lu, L; Xu, G-T

2017-01-01

Human umbilical cord mesenchymal stem cells (hUC-MSCs) are potential candidates for treating retinal degeneration (RD). To further study the biology and therapeutic effects of the hUC-MSCs on retinal degeneration. Two hUC-MSC subpopulations, termed hUC-MSC1 and hUC-MSC2, were isolated by single-cell cloning method and their therapeutic functions were compared in RCS rat, a RD model. Although both subsets satisfied the basic requirements for hUC-MSCs, they were significantly different in morphology, proliferation rate, differentiation capacity, phenotype and gene expression. Furthermore, only the smaller, fibroblast-like, faster growing subset hUC-MSC1 displayed stronger colony forming potential as well as adipogenic and osteogenic differentiation capacities. When the two subsets were respectively transplanted into the subretinal spaces of RCS rats, both subsets survived, but only hUC-MSC1 expressed RPE cell markers Bestrophin and RPE65. More importantly, hUC-MSC1 showed stronger rescue effect on the retinal function as indicated by the higher b-wave amplitude on ERG examination, thicker retinal nuclear layer, and decreased apoptotic photoreceptors. When both subsets were treated with interleukin-6, mimicking the inflammatory environment when the cells were transplanted into the eyes with degenerated retina, hUC-MSC1 expressed much higher levels of trophic factors in comparison with hUC-MSC2. The data here, in addition to prove the heterogeneity of hUC-MSCs, confirmed that the stronger therapeutic effects of hUC-MSC1 were attributed to its stronger anti-apoptotic effect, paracrine of trophic factors and potential RPE cell differentiation capacity. Thus, the subset hUC-MSC1, not the other subset or the ungrouped hUC-MSCs should be used for effective treatment of RD. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Proton conduction within the reaction centers of Rhodobacter capsulatus: the electrostatic role of the protein.

Science.gov (United States)

Maróti, P; Hanson, D K; Baciou, L; Schiffer, M; Sebban, P

1994-06-07

Light-induced charge separation in the photosynthetic reaction center results in delivery of two electrons and two protons to the terminal quinone acceptor QB. In this paper, we have used flash-induced absorbance spectroscopy to study three strains that share identical amino acid sequences in the QB binding site, all of which lack the protonatable amino acids Glu-L212 and Asp-L213. These strains are the photosynthetically incompetent site-specific mutant Glu-L212/Asp-L213-->Ala-L212/Ala-L213 and two different photocompetent derivatives that carry both alanine substitutions and an intergenic suppressor mutation located far from QB (class 3 strain, Ala-Ala + Arg-M231-->Leu; class 4 strain, Ala-Ala + Asn-M43-->Asp). At pH 8 in the double mutant, we observe a concomitant decrease of nearly 4 orders of magnitude in the rate constants of second electron and proton transfer to QB compared to the wild type. Surprisingly, these rates are increased to about the same extent in both types of suppressor strains but remain > 2 orders of magnitude smaller than those of the wild type. In the double mutant, at pH 8, the loss of Asp-L213 and Glu-L212 leads to a substantial stabilization (> or = 60 meV) of the semiquinone energy level. Both types of compensatory mutations partially restore, to nearly the same level, the original free energy difference for electron transfer from primary quinone QA to QB. The pH dependence of the electron and proton transfer processes in the double-mutant and the suppressor strains suggests that when reaction centers of the double mutant are shifted to lower pH (1.5-2 units), they function like those of the suppressor strains at physiological pH. Our data suggest that the main effect of the compensatory mutations is to partially restore the negative electrostatic environment of QB and to increase an apparent "functional" pK of the system for efficient proton transfer to the active site. This emphasizes the role of the protein in tuning the

Pathways and timescales of primary charge separation in the photosystem II reaction center as revealed by a simultaneous fit of time-resolved fluorescence and transient absorption

NARCIS (Netherlands)

Novoderezhkin, V.I.; Andrizhiyevskaya, E.G.; Dekker, J.P.; van Grondelle, R.

2005-01-01

We model the dynamics of energy transfer and primary charge separation in isolated photosystem II (PSII) reaction centers. Different exciton models with specific site energies of the six core pigments and two peripheral chlorophylls (Chls) in combination with different charge transfer schemes have

Efficient Destruction of Pollutants in Water by a Dual-Reaction-Center Fenton-like Process over Carbon Nitride Compounds-Complexed Cu(II)-CuAlO2.

Science.gov (United States)

Lyu, Lai; Yan, Dengbiao; Yu, Guangfei; Cao, Wenrui; Hu, Chun

2018-04-03

Carbon nitride compounds (CN) complexed with the in-situ-produced Cu(II) on the surface of CuAlO 2 substrate (CN-Cu(II)-CuAlO 2 ) is prepared via a surface growth process for the first time and exhibits exceptionally high activity and efficiency for the degradation of the refractory pollutants in water through a Fenton-like process in a wide pH range. The reaction rate for bisphenol A removal is ∼25 times higher than that of the CuAlO 2 . According to the characterization, Cu(II) generation on the surface of CuAlO 2 during the surface growth process results in the marked decrease of the surface oxygen vacancies and the formation of the C-O-Cu bridges between CN and Cu(II)-CuAlO 2 in the catalyst. The electron paramagnetic resonance (EPR) analysis and density functional theory (DFT) calculations demonstrate that the dual reaction centers are produced around the Cu and C sites due to the cation-π interactions through the C-O-Cu bridges in CN-Cu(II)-CuAlO 2 . During the Fenton-like reactions, the electron-rich center around Cu is responsible for the efficient reduction of H 2 O 2 to • OH, and the electron-poor center around C captures electrons from H 2 O 2 or pollutants and diverts them to the electron-rich area via the C-O-Cu bridge. Thus, the catalyst exhibits excellent catalytic performance for the refractory pollutant degradation. This study can deepen our understanding on the enhanced Fenton reactivity for water purification through functionalizing with organic solid-phase ligands on the catalyst surface.

Phenomena occurring in the reactor coolant system during severe core damage accidents

International Nuclear Information System (INIS)

Malinauskas, A.P.

1989-01-01

The reactor coolant system (RCS) of a nuclear power plant consists of the reactor pressure vessel and the piping and associated components that are required for the continuous circulation of the coolant which is used to maintain thermal equilibrium throughout the system. In the event of an accident, the RCS also serves as one of several barriers to the escape of radiotoxic material into the biosphere. In contrast to normal operating conditions, severe core damage accidents are characterized by significant temporal and spatial variations in heat and mass fluxes, and by eventual geometrical changes within the RCS. Furthermore, the difficulties in describing the system in the severe accident mode are compounded by the occurrence of chemical reactions. These reactions can influence both the thermal and the mass transport behavior of the system. In addition, behavior of the reactor vessel internals and of materials released from the core region (especially the radioactive fission products) in the course of the accident likewise become of concern to the analyst. This report addresses these concerns. 9 refs., 1 tab

Respiratory hypersensitivity reactions to NSAIDs in Europe

DEFF Research Database (Denmark)

Makowska, J S; Burney, P; Jarvis, D

2016-01-01

BACKGROUND: Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most prevalent drugs inducing hypersensitivity reactions. The aim of this analysis was to estimate the prevalence of NSAID-induced respiratory symptoms in population across Europe and to assess its association with upper...... and lower respiratory tract disorders. METHODS: The GA(2) LEN survey was conducted in 22 centers in 15 European countries. Each of 19 centers selected random samples of 5000 adults aged 15-74 from their general population, and in three centers (Athens, Munich, Oslo), a younger population was sampled...... prevalence of NSAID-induced dyspnea was 1.9% and was highest in the three Polish centers [Katowice (4.9%), Krakow (4.8%), and Lodz (4.4%)] and lowest in Skopje, (0.9%), Amsterdam (1.1%), and Umea (1.2%). In multivariate analysis, the prevalence of respiratory reactions to NSAIDs was higher in participants...

Survival and Functionality of hESC-Derived Retinal Pigment Epithelium Cells Cultured as a Monolayer on Polymer Substrates Transplanted in RCS Rats.

Science.gov (United States)

Thomas, Biju B; Zhu, Danhong; Zhang, Li; Thomas, Padmaja B; Hu, Yuntao; Nazari, Hossein; Stefanini, Francisco; Falabella, Paulo; Clegg, Dennis O; Hinton, David R; Humayun, Mark S

2016-05-01

To determine the safety, survival, and functionality of human embryonic stem cell-derived RPE (hESC-RPE) cells seeded on a polymeric substrate (rCPCB-RPE1 implant) and implanted into the subretinal (SR) space of Royal College of Surgeons (RCS) rats. Monolayers of hESC-RPE cells cultured on parylene membrane were transplanted into the SR space of 4-week-old RCS rats. Group 1 (n = 46) received vitronectin-coated parylene membrane without cells (rMSPM+VN), group 2 (n = 59) received rCPCB-RPE1 implants, and group 3 (n = 13) served as the control group. Animals that are selected based on optical coherence tomography screening were subjected to visual function assays using optokinetic (OKN) testing and superior colliculus (SC) electrophysiology. At approximately 25 weeks of age (21 weeks after surgery), the eyes were examined histologically for cell survival, phagocytosis, and local toxicity. Eighty-seven percent of the rCPCB-RPE1-implanted animals showed hESC-RPE survivability. Significant numbers of outer nuclear layer cells were rescued in both group 1 (rMSPM+VN) and group 2 (rCPCB-RPE1) animals. A significantly higher ratio of rod photoreceptor cells to cone photoreceptor cells was found in the rCPCB-RPE1-implanted group. Animals with rCPCB-RPE1 implant showed hESC-RPE cells containing rhodopsin-positive particles in immunohistochemistry, suggesting phagocytic function. Superior colliculus mapping data demonstrated that a significantly higher number of SC sites responded to light stimulus at a lower luminance threshold level in the rCPCB-RPE1-implanted group. Optokinetic data suggested both implantation groups showed improved visual acuity. These results demonstrate the safety, survival, and functionality of the hESC-RPE monolayer transplantation in an RPE dysfunction rat model.

Photochemistry and reactions of OH- defects and F centers in alkali halides

International Nuclear Information System (INIS)

Morato, S.P.; Luety, F.

1978-01-01

Aditively colored KCl:OH - crystals showed under a combined UV and VIS irradiation, a nearly complete and irreversible destruction of all F centers and visible absorption in the crystal. Only upon heating the crystal above 650 0 C the F center coloration becomes partially restored. The photodissociation of the OH - (under UV light) together with the photoionization of the F center (under VIS light) produces a not effects where all the F centers are converted into U centers. These photoreactions produces high contrast visible images that are completely stable under light at RT. Besides the optical information storage aspect of this effect these photoreaction s can also be used for controlled production of Usub(A) centers if the crystal also contains a foreign metallic impurity such a Na + ion [pt

Assembly of photosynthetic reaction center with ABA tri-block polymersomes: highlights on the protein localization.

KAUST Repository

Tangorra, Roberto Rocco

2015-07-07

The reconstitution of the integral membrane protein photosynthetic reaction center (RC) in polymersomes, i. e. artificial closed vesicles, was achieved by the micelle-to-vesicle transition technique, a very mild protocol based on size exclusion chromatography often used to drive the incorporation of proteins contemporarily to liposomes formation. An optimized protocol was used to successfully reconstitute the protein in a fully active state in polymersomes formed by the tri-block copolymers PMOXA22-PDMS61-PMOXA22. The RC is very sensitive to its solubilizing environment and was used to probe the positioning of the protein in the vesicles. According to charge-recombination experiments and to the enzymatic activity assay, the RC is found to accommodate in the PMOXA22 region of the polymersome, facing the water bulk solution, rather than in the PDMS61 transmembrane-like region. Furthermore, polymersomes were found to preserve protein integrity efficiently as the biomimetic lipid bilayers but show a much longer temporal stability than lipid based vesicles.

Assembly of photosynthetic reaction center with ABA tri-block polymersomes: highlights on the protein localization.

KAUST Repository

Tangorra, Roberto Rocco; Operamolla, Alessandra; Milano, Francesco; Hassan Omar, Omar; Henrard, John; Comparelli, Roberto; Italiano, Francesca; Agostiano, Angela; De Leo, Vincenzo; Marotta, Roberto; Falqui, Andrea; Farinola, Gianluca; Trotta, Massimo

2015-01-01

The reconstitution of the integral membrane protein photosynthetic reaction center (RC) in polymersomes, i. e. artificial closed vesicles, was achieved by the micelle-to-vesicle transition technique, a very mild protocol based on size exclusion chromatography often used to drive the incorporation of proteins contemporarily to liposomes formation. An optimized protocol was used to successfully reconstitute the protein in a fully active state in polymersomes formed by the tri-block copolymers PMOXA22-PDMS61-PMOXA22. The RC is very sensitive to its solubilizing environment and was used to probe the positioning of the protein in the vesicles. According to charge-recombination experiments and to the enzymatic activity assay, the RC is found to accommodate in the PMOXA22 region of the polymersome, facing the water bulk solution, rather than in the PDMS61 transmembrane-like region. Furthermore, polymersomes were found to preserve protein integrity efficiently as the biomimetic lipid bilayers but show a much longer temporal stability than lipid based vesicles.

Enantio- and Stereoselective Construction of Atisane Scaffold via Organocatalytic Intramolecular Michael Reaction and Diels-Alder Reaction.

Science.gov (United States)

Sekita, Hiroko; Adachi, Kyohei; Kobayashi, Ippei; Sato, Yusuke; Nakada, Masahisa

2017-05-05

An enantio- and stereoselective construction of the atisane scaffold via organocatalytic intramolecular Michael reaction and Diels-Alder reaction is described. The organocatalytic intramolecular Michael reaction has been found to stereoselectively generate a trans-stereodiad comprising an all-carbon quaternary and a tertiary stereogenic centers. Use of the chiral secondary amine bearing thiourea with benzoic acid as additive is the key to obtaining the desired product with excellent ee in synthetically acceptable yield. The prepared chiral building block has been successfully converted to the compound including the atisane scaffold via the highly stereoselective intramolecular Diels-Alder reaction.

[Prevalence of reactions secundary to mosquito bites Aedes aegypti at en el Regional Center of Allergy and Clinical Immunology, University Hospital, de Monterrey, Nuevo Leon].

Science.gov (United States)

González Diaz, Sandra Nora; Cruz, Alfredo Arias; Sedó Mejía, Giovanni A; Rojas Lozano, Antonio A; Valenzuela, Enrique Avitia; Vidaurri Ojeda, Alma C

2010-01-01

although systemic reactions resulting from hymenoptera stings have been studied extensively, the prevalence of allergic reactions to mosquitoes is unknown. to investigate the prevalence of allergic reactions to Aedes aegypti bites in patients seeking treatment at the Allergy and Clinical Immunology Regional Center of Jose E Gonzalez University Hospital in Monterrey, Mexico. we carried out a cross-sectional, descriptive study that included patients receiving skin tests for aeroallergens; skin sensitivity to mosquito bites was also tested. A questionnaire was used to obtain information about previous allergic reactions to mosquito bites. a total of 482 patients between 2 and 60 years of age were included; 53% were female, 407 (84.4%) had a history of local reactions to mosquito bites. Twelve patients (2.4%) stated a history of large local reaction; three (0.6%) of them with a positive skin prick test, one (0.2%) of those had systemic reaction history to mosquito. Eighty five (17.6%) patients had a positive mosquito skin test and 307 (63.6%) had a positive skin test for at least one aeroallergen. Seventy-eight (91.7%) of the 85 patients with a positive mosquito skin test had a history of local skin reactions to mosquito bite (odds ratio: 2.303 [confidence interval (CI) 1.037-5.10]. There was no statistically significance association between allergic diseases and mosquito allergy. adverse reactions and allergic reactions to mosquito bites occur frequently. However mosquito allergy is low. Further studies are required to determine the prevalence of mosquito allergy in the general population.

Study of the Mn-binding sites in photosystem II using antibodies raised against lumenal regions of the D1 and D2 reaction center proteins

Energy Technology Data Exchange (ETDEWEB)

Dalmasso, Enrique Agustin [Univ. of California, Berkeley, CA (United States)

1992-04-01

The experiments discussed in this thesis focus on identifying the protein segments or specific amino acids which provide ligands to the Mn cluster of photosystem II (PS II). This Mn cluster plays a central role in the oxygen-evolving complex (OEC) of PS II. The Mn cluster is thought to be bound by lumenal regions of the PS II reaction center proteins known as D1 and D2. First, several peptides were synthesized which correspond to specific lumenal segments of the D1 and D2 proteins. Next, polyclonal antibodies were successfully elicited using three of these peptides. The peptides recognized by these antibodies correspond to protein segments of the spinach reaction center proteins: Ile-321 to Ala-344 of D1 (D1-a), Asp-319 to Arg-334 of D1 (D1-b), and Val-300 to Asn-319 of D2 (D2-a). These antibodies were then used in assays which were developed to structurally or functionally probe the potential Mn-binding regions of the D1 and D2 proteins.

Insights into factors contributing to the observability of a submarine at periscope depth by modern radar, Part 2: EM simulation of mast RCS in a realistic sea surface environment

CSIR Research Space (South Africa)

Smit, JC

2012-09-01

Full Text Available IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC), Cape Town 2-7 September 2012 Insights into factors contributing to the observability of a submarine at periscope depth by modern radar, Part 2: EM... simulation of mast RCS in a realistic sea surface environment Smit JC; Cilliers JE CSIR, Defence, Peace, Safety and Security. PO Box 395, Pretoria, 0001 Abstract Recently, a set of high resolution radar measurements were undertaken in South...

Fragment molecular orbital study on electron tunneling mechanisms in bacterial photosynthetic reaction center.

Science.gov (United States)

Kitoh-Nishioka, Hirotaka; Ando, Koji

2012-11-01

The tunneling mechanisms of electron transfers (ETs) in photosynthetic reaction center of Blastochloris viridis are studied by the ab initio fragment molecular orbital (FMO) method combined with the generalized Mulliken-Hush (GMH) and the bridge Green function (GF) calculations of the electronic coupling T(DA) and the tunneling current method for the ET pathway analysis at the fragment-based resolution. For the ET from batctriopheophytin (H(L)) to menaquinone (MQ), a major tunneling current through Trp M250 and a minor back flow via Ala M215, Ala M216, and His M217 are quantified. For the ET from MQ to ubiquinone, the major tunneling pathway via the nonheme Fe(2+) and His L190 is identified as well as minor pathway via His M217 and small back flows involving His L230, Glu M232, and His M264. At the given molecular structure from X-ray experiment, the spin state of the Fe(2+) ion, its replacement by Zn(2+), or its removal are found to affect the T(DA) value by factors within 2.2. The calculated T(DA) values, together with experimentally estimated values of the driving force and the reorganization energy, give the ET rates in reasonable agreement with experiments.

Structure-reactivity modeling using mixture-based representation of chemical reactions.

Science.gov (United States)

Polishchuk, Pavel; Madzhidov, Timur; Gimadiev, Timur; Bodrov, Andrey; Nugmanov, Ramil; Varnek, Alexandre

2017-09-01

We describe a novel approach of reaction representation as a combination of two mixtures: a mixture of reactants and a mixture of products. In turn, each mixture can be encoded using an earlier reported approach involving simplex descriptors (SiRMS). The feature vector representing these two mixtures results from either concatenated product and reactant descriptors or the difference between descriptors of products and reactants. This reaction representation doesn't need an explicit labeling of a reaction center. The rigorous "product-out" cross-validation (CV) strategy has been suggested. Unlike the naïve "reaction-out" CV approach based on a random selection of items, the proposed one provides with more realistic estimation of prediction accuracy for reactions resulting in novel products. The new methodology has been applied to model rate constants of E2 reactions. It has been demonstrated that the use of the fragment control domain applicability approach significantly increases prediction accuracy of the models. The models obtained with new "mixture" approach performed better than those required either explicit (Condensed Graph of Reaction) or implicit (reaction fingerprints) reaction center labeling.

Neurosurgery certification in member societies of the World Federation of Neurosurgical Societies: Asia.

Science.gov (United States)

Gasco, Jaime; Braun, Jonathan D; McCutcheon, Ian E; Black, Peter M

2011-01-01

To objectively compare the complexity and diversity of the certification process in neurological surgery in member societies of the World Federation of Neurosurgical Societies. This study centers in continental Asia. We provide here an analysis based on the responses provided to a 13-item survey. The data received were analyzed, and three Regional Complexity Scores (RCS) were designed. To compare national board experience, eligibility requirements for access to the certification process, and the obligatory nature of the examinations, an RCS-Organizational score was created (20 points maximum). To analyze the complexity of the examination, an RCS-Components score was designed (20 points maximum). The sum of both is presented in a Global RCS score. Only those countries that responded to the survey and presented nationwide homogeneity in the conduction of neurosurgery examinations could be included within the scoring system. In addition, a descriptive summary of the certification process per responding society is also provided. On the basis of the data provided by our RCS system, the highest global RCS was achieved by South Korea and Malaysia (21/40 points) followed by the joint examination of Singapore and Hong-Kong (FRCS-Ed) (20/40 points), Japan (17/40 points), the Philippines (15/40 points), and Taiwan (13 points). The experience from these leading countries should be of value to all countries within Asia. Copyright © 2011 Elsevier Inc. All rights reserved.

Sélection de variétés d'oignon (Allium cepa L. adaptées au nord de la Côte d'Ivoire

Directory of Open Access Journals (Sweden)

Coulibaly, MY.

2003-01-01

Full Text Available Selection of Varieties Onion (Allium cepa L. Adapted to the North of Ivory Coast. Sixteen varieties of onion from the collection of the National Agronomical Research Center were evaluated on the basis of their performance in the North of Ivory Coast, during the agricultural season 1998- 1999. This evaluation was made in the presence of a local control, Violet de Galmi, at the station of production of onion seeds of the Rural Development Support National Agency. Varieties Rouge de Tana, RCS1903, RCS2211 and RCS2302 gave a higher rate of healthy bulbs (64.07% on average than the others. For the total yield, varieties RCS1903, RCS2211 and RCS2302 produced more (18.18 t/ha on average than Violet de Galmi (14.58 t/ha. The latter was more productive than Rouge de Tana (12.56 t/ha. However only the purple variety, Rouge de Tana had a high content of dry matter (20.86% and was good preserved with nearly 95% of healthy bulbs after 3 months of storage, like the local control. Significant correlations appeared between the various studied characters. The most significant correlation was observed between the date of harvest and the percentage of layering at 100 days (r= -0.858; and the rate of healthy bulbs after 3 months of storage and the content of dry matter (r= 0.847.

[High activity antiretroviral therapy change associated to adverse drug reactions in a specialized center in Venezuela].

Science.gov (United States)

Subiela, José D; Dapena, Elida

2016-03-01

Adverse drug reactions (ADRs) represent the first cause of change of the first-line highly active antiretroviral therapy (HAART) regimen, therefore, they constitute the main limiting factor in the long-term follow up of HIV patients in treatment. A retrospective study was carried out in a specialized center in Lara State, Venezuela, including 99 patients over 18 years of age who had change of first-line HAART regimen due to ADRs, between 2010 and 2013. The aims of this research were to describe the sociodemographic and clinical variables, frequency of ADRs related to change of HAART, duration of the first-line HAART regimen, to determine the drugs associated with ARVs and to identify the risk factors. The ADRs constituted 47.5% of all causes of change of first-line HAART regimen, the median duration was 1.08±0.28 years. The most frequent ADRs were anemia (34.3%), hypersensitivity reactions (20.2%) and gastrointestinal intolerance (13.1%). The most frequent ARV regimen type was the protease inhibitors-based regimen (59.6%), but zidovudine was the ARV most linked to ADRs (41.4%). The regression analysis showed increased risk of ADRs in singles and students in the univariate analysis and heterosexuals and homosexuals in multivariate analysis; and decreased risk in active workers. The present work shows the high prevalence of ADRs in the studied population and represents the first case-based study that describes the pharmacoepidemiology of a cohort of HIV-positive patients treated in Venezuela.

Electromagnetic scattering by a uniaxial anisotropic sphere located in an off-axis Bessel beam.

Science.gov (United States)

Qu, Tan; Wu, Zhen-Sen; Shang, Qing-Chao; Li, Zheng-Jun; Bai, Lu

2013-08-01

Electromagnetic scattering of a zero-order Bessel beam by an anisotropic spherical particle in the off-axis configuration is investigated. Based on the spherical vector wave functions, the expansion expression of the zero-order Bessel beam is derived, and its convergence is numerically discussed in detail. Utilizing the tangential continuity of the electromagnetic fields, the expressions of scattering coefficients are given. The effects of the conical angle of the wave vector components of the zero-order Bessel beam, the ratio of the radius of the sphere to the central spot radius of the zero-order Bessel beam, the shift of the beam waist center position along both the x and y axes, the permittivity and permeability tensor elements, and the loss of the sphere on the radar cross section (RCS) are numerically analyzed. It is revealed that the maximum RCS appears in the conical direction or neighboring direction when the sphere is illuminated by a zero-order Bessel beam. Furthermore, the RCS will decrease and the symmetry is broken with the shift of the beam waist center.

Effects on RCS of a perfect electromagnetic conductor sphere in the presence of anisotropic plasma layer

Science.gov (United States)

Ghaffar, A.; Hussan, M. M.; Illahi, A.; Alkanhal, Majeed A. S.; Ur Rehman, Sajjad; Naz, M. Y.

2018-01-01

Effects on RCS of perfect electromagnetic conductor (PEMC) sphere by coating with anisotropic plasma layer are studied in this paper. The incident, scattered and transmitted electromagnetic fields are expanded in term of spherical vector wave functions using extended classical theory of scattering. Co and cross-polarized scattered field coefficients are obtained at the interface of free space-anisotropic plasma and at anisotropic plasma-PEMC sphere core by scattering matrices method. The presented analytical expressions are general for any perfect conducting sphere (PMC, PEC, or PEMC) with general anisotropic/isotropic material coatings that include plasma and metamaterials. The behavior of the forward and backscattered radar cross section of PEMC sphere with the variation of the magnetic field strength, incident frequency, plasma density, and effective collision frequency for the co-polarized and the cross polarized fields are investigated. It is also observed from the obtained results that anisotropic layer on PEMC sphere shows reciprocal behavior as compared to isotopic plasma layer on PEMC sphere. The comparisons of the numerical results of the presented analytical expressions with available results of some special cases show the correctness of the analysis.

Chronic intravitreous infusion of ciliary neurotrophic factor modulates electrical retinal stimulation thresholds in the RCS rat.

Science.gov (United States)

Kent, Tiffany L; Glybina, Inna V; Abrams, Gary W; Iezzi, Raymond

2008-01-01

To determine whether the sustained intravitreous delivery of CNTF modulates cortical response thresholds to electrical retinal stimulation in the RCS rat model of retinal degeneration. Animals were assigned to four groups: untreated, nonsurgical control and infusion groups of 10 ng/d CNTF, 1 ng/d CNTF, and PBS vehicle control. Thresholds for electrically evoked cortical potentials (EECPs) were recorded in response to transcorneal electrical stimulation of the retina at p30 and again at p60, after a three-week infusion. As the retina degenerated over time, EECP thresholds in response to electrical retinal stimulation increased. Eyes treated with 10 ng/d CNTF demonstrated significantly greater retinal sensitivity to electrical stimulation when compared with all other groups. In addition, eyes treated with 1 ng/d CNTF demonstrated significantly greater retinal sensitivity than both PBS-treated and untreated control groups. Retinal sensitivity to electrical stimulation was preserved in animals treated with chronic intravitreous infusion of CNTF. These data suggest that CNTF-mediated retinal neuroprotection may be a novel therapy that can lower stimulus thresholds in patients about to undergo retinal prosthesis implantation. Furthermore, it may maintain the long-term efficacy of these devices in patients.

Remote Cloud Sensing Intensive Observation Period (RCS-IOP) millimeter-wave radar calibration and data intercomparison

Energy Technology Data Exchange (ETDEWEB)

Sekelsky, S.M.; Firda, J.M.; McIntosh, R.E. [Univ. of Massachusetts, Amherst, MA (United States)] [and others

1996-04-01

During April 1994, the University of Massachusetts (UMass) and the Pennsylvania State University (Penn State) fielded two millimeter-wave atmospheric radars in the Atmospheric Radiation Measurement Remote Cloud Sensing Intensive Operation Period (RCS-IOP) experiment. The UMass Cloud Profiling Radar System (CPRS) operates simultaneously at 33.12 GHz and 94.92 GHz through a single antenna. The Penn State radar operates at 93.95 GHz and has separate transmitting and receiving antennas. The two systems were separated by approximately 75 meters and simultaneously observed a variety of cloud types at verticle incidence over the course of the experiment. This abstract presents some initial results from our calibration efforts. An absolute calibration of the UMass radar was made from radar measurements of a trihedral corner reflector, which has a known radar cross-section. A relative calibration of between the Penn State and UMass radars is made from the statistical comparison of zenith pointing measurements of low altitude liquid clouds. Attenuation is removed with the aid of radiosonde data, and the difference in the calibration between the UMass and Penn State radars is determined by comparing the ratio of 94-GHz and 95-GHz reflectivity values to a model that accounts for parallax effects of the two antennas used in the Penn State system.

Orion Handling Qualities During ISS Rendezvous and Docking

Science.gov (United States)

Hart, Jeremy J.; Stephens, J. P.; Spehar, P.; Bilimoria, K.; Foster, C.; Gonzalex, R.; Sullivan, K.; Jackson, B.; Brazzel, J.; Hart, J.

2011-01-01

The Orion spacecraft was designed to rendezvous with multiple vehicles in low earth orbit (LEO) and beyond. To perform the required rendezvous and docking task, Orion must provide enough control authority to perform coarse translational maneuvers while maintaining precision to perform the delicate docking corrections. While Orion has autonomous docking capabilities, it is expected that final approach and docking operations with the International Space Station (ISS) will initially be performed in a manual mode. A series of evaluations was conducted by NASA and Lockheed Martin at the Johnson Space Center to determine the handling qualities (HQ) of the Orion spacecraft during different docking and rendezvous conditions using the Cooper-Harper scale. This paper will address the specifics of the handling qualities methodology, vehicle configuration, scenarios flown, data collection tools, and subject ratings and comments. The initial Orion HQ assessment examined Orion docking to the ISS. This scenario demonstrates the Translational Hand Controller (THC) handling qualities of Orion. During this initial assessment, two different scenarios were evaluated. The first was a nominal docking approach to a stable ISS, with Orion initializing with relative position dispersions and a closing rate of approximately 0.1 ft/sec. The second docking scenario was identical to the first, except the attitude motion of the ISS was modeled to simulate a stress case ( 1 degree deadband per axis and 0.01 deg/sec rate deadband per axis). For both scenarios, subjects started each run on final approach at a docking port-to-port range of 20 ft. Subjects used the THC in pulse mode with cues from the docking camera image, window views, and range and range rate data displayed on the Orion display units. As in the actual design, the attitude of the Orion vehicle was held by the automated flight control system at 0.5 degree deadband per axis. Several error sources were modeled including Reaction

Development of odd-Z-projectile reactions for transactinide element synthesis

International Nuclear Information System (INIS)

Folden III, Charles Marvin

2004-01-01

The development of new odd-Z-projectile reactions leading to the production of transactinide elements is described. The cross section of the even-Z-projectile 208Pb(64Ni, n)271Ds reaction was measured at two new energies using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. In total, seven decay chains attributable to 271Ds were observed. These data, combined with previous results, establish an excitation function for the production of 271Ds. The maximum cross section was 20 +15 -11 pb at a center-of-target energy of 311.5 MeV in the laboratory frame.The data from the 271Ds experiments were used to estimate the optimum beam energy for the new odd-Z-projectile 208Pb(65Cu, n)272-111 reaction using the Fusion by Diffusion theory proposed by Swiatecki, Siwek-Wilczynska, and Wilczynski. A cross section for this reaction was measured for the first time, at a center-of-target energy of 321.1 MeV in the laboratory frame. The excitation energy f or compound nuclei formed at the target center was 13.2 MeV. One decay chain was observed, resulting in a measured cross section of 1.7 +3.9 -1.4 pb. This decay chain is in good agreement with previously published data on the decay of 272-111.The new odd-Z-projectile 208Pb(55Mn, n)262Bh reaction was studied at three different projectile energies, and 33 decay chains of 262Bh were observed. The existence of a previously reported alpha-decaying isomeric state in this nuclide was confirmed. Production of the ground state was preferred at all three beam energies. The maximum cross section was 540 +180 -150 pb at a projectile center-of-target energy of 264.0 MeV. This cross section is much larger than that previously reported for the even-Z-projectile 209Bi(54Cr, n)262Bh reaction, which may be because the 54Cr projectile energies in the latter reaction were too high for optimum production of the 1n product. At the highest projectile energy of 268.0 MeV in the target center, two decay

Chemical potential and reaction electronic flux in symmetry controlled reactions.

Science.gov (United States)

Vogt-Geisse, Stefan; Toro-Labbé, Alejandro

2016-07-15

In symmetry controlled reactions, orbital degeneracies among orbitals of different symmetries can occur along a reaction coordinate. In such case Koopmans' theorem and the finite difference approximation provide a chemical potential profile with nondifferentiable points. This results in an ill-defined reaction electronic flux (REF) profile, since it is defined as the derivative of the chemical potential with respect to the reaction coordinate. To overcome this deficiency, we propose a new way for the calculation of the chemical potential based on a many orbital approach, suitable for reactions in which symmetry is preserved. This new approach gives rise to a new descriptor: symmetry adapted chemical potential (SA-CP), which is the chemical potential corresponding to a given irreducible representation of a symmetry group. A corresponding symmetry adapted reaction electronic flux (SA-REF) is also obtained. Using this approach smooth chemical potential profiles and well defined REFs are achieved. An application of SA-CP and SA-REF is presented by studying the Cs enol-keto tautomerization of thioformic acid. Two SA-REFs are obtained, JA'(ξ) and JA'' (ξ). It is found that the tautomerization proceeds via an in-plane delocalized 3-center 4-electron O-H-S hypervalent bond which is predicted to exist only in the transition state (TS) region. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Two Red Clumps and the X-shaped Milky Way Bulge

Science.gov (United States)

McWilliam, Andrew; Zoccali, Manuela

2010-12-01

From Two Micron All Sky Survey infrared photometry, we find two red clump (RC) populations coexisting in fields toward the Galactic bulge at latitudes |b|>5fdg5, ranging over ~13° in longitude and 20° in latitude. These RC peaks indicate two stellar populations separated by ~2.3 kpc at (l, b) = (+1, - 8) the two RCs are located at 6.5 and 8.8 ± 0.2 kpc. The double-peaked RC is inconsistent with a tilted bar morphology. Most of our fields show the two RCs at roughly constant distance with longitude, also inconsistent with a tilted bar; however, an underlying bar may be present. Stellar densities in the two RCs change dramatically with longitude: on the positive longitude side the foreground RC is dominant, while the background RC dominates negative longitudes. A line connecting the maxima of the foreground and background populations is tilted to the line of sight by ~20°±4°, similar to claims for the tilt of a Galactic bar. The distance between the two RCs decreases toward the Galactic plane; seen edge-on the bulge is X-shaped, resembling some extragalactic bulges and the results of N-body simulations. The center of this X is consistent with the distance to the Galactic center, although better agreement would occur if the bulge is 2-3 Gyr younger than 47 Tuc. Our observations may be understood if the two RC populations emanate, nearly tangentially, from the Galactic bar ends, in a funnel shape. Alternatively, the X, or double funnel, may continue to the Galactic center. From the Sun, this would appear peanut/box shaped, but X-shaped when viewed tangentially.

EXFOR basics: A short guide to the nuclear reaction data exchange format

International Nuclear Information System (INIS)

McLane, V.

1996-07-01

This manual is intended as a guide to users of nuclear reaction data compiled in the EXFOR format, and is not intended as a complete guide to the EXFOR System. EXFOR is the exchange format designed to allow transmission of nuclear data between the Nuclear Reaction Data Centers. In addition to storing the data and its' bibliographic information, experimental information, including source of uncertainties, is also compiled. The status and history of the data set is also included, e.g., the source of the data, any updates which have been made, and correlations to other data sets. EXFOR is designed for flexibility in order to meet the diverse needs of the nuclear data compilation centers. This format should not be confused with a center-to-user format. Although users may obtain data from the centers in the EXFOR format, other center-to-user formats have been developed to meet the needs of the users within each center's own sphere of responsibility. The exchange format, as outlined, allows a large variety of numerical data tables with explanatory and bibliographic information to be transmitted in an easily machine-readable format (for checking and indicating possible errors) and a format that can be read by personnel (for passing judgment on and correcting any errors indicated by the machine). The data presently included in the EXFOR exchange include: a complete compilation of experimental neutron-induced reaction data, a selected compilation of charged-particle induced reaction data, a selected compilation of photon-induced reaction data

Accelerator Center for Energy Research (ACER)

Data.gov (United States)

Federal Laboratory Consortium — The Accelerator Center for Energy Research (ACER) exploits radiation chemistry techniques to study chemical reactions (and other phenomena) by subjecting samples to...

Plasma distributions in meteor head echoes and implications for radar cross section interpretation

Science.gov (United States)

Marshall, Robert A.; Brown, Peter; Close, Sigrid

2017-09-01

The derivation of meteoroid masses from radar measurements requires conversion of the measured radar cross section (RCS) to meteoroid mass. Typically, this conversion passes first through an estimate of the meteor plasma density derived from the RCS. However, the conversion from RCS to meteor plasma density requires assumptions on the radial electron density distribution. We use simultaneous triple-frequency measurements of the RCS for 63 large meteor head echoes to derive estimates of the meteor plasma size and density using five different possible radial electron density distributions. By fitting these distributions to the observed meteor RCS values and estimating the goodness-of-fit, we determine that the best fit to the data is a 1 /r2 plasma distribution, i.e. the electron density decays as 1 /r2 from the center of the meteor plasma. Next, we use the derived plasma distributions to estimate the electron line density q for each meteor using each of the five distributions. We show that depending on the choice of distribution, the line density can vary by a factor of three or more. We thus argue that a best estimate for the radial plasma distribution in a meteor head echo is necessary in order to have any confidence in derived meteoroid masses.

Advanced Development of a Compact 5-15 lbf Lox/Methane Thruster for an Integrated Reaction Control and Main Engine Propulsion System

Science.gov (United States)

Hurlbert, Eric A.; McManamen, John Patrick; Sooknanen, Josh; Studak, Joseph W.

2011-01-01

This paper describes the advanced development and testing of a compact 5 to 15 lbf LOX/LCH4 thruster for a pressure-fed integrated main engine and RCS propulsion system to be used on a spacecraft "vertical" test bed (VTB). The ability of the RCS thruster and the main engine to operate off the same propellant supply in zero-g reduces mass and improves mission flexibility. This compact RCS engine incorporates several features to dramatically reduce mass and parts count, to ease manufacturing, and to maintain acceptable performance given that specific impulse (Isp) is not the driver. For example, radial injection holes placed on the chamber body for easier drilling, and high temperature Haynes 230 were selected for the chamber over other more expensive options. The valve inlets are rotatable before welding allowing different orientations for vehicle integration. In addition, the engine design effort selected a coil-on-plug ignition system which integrates a relay and coil with the plug electrode, and moves some exciter electronics to avionics driver board. The engine injector design has small dribble volumes to target minimum pulse widths of 20 msec. and an efficient minimum impulse bit of less than 0.05 lbf-sec. The propellants, oxygen and methane, were chosen because together they are a non-toxic, Mars-forward, high density, space storable, and high performance propellant combination that is capable of pressure-fed and pump-fed configurations and integration with life support and power subsystems. This paper will present the results of the advanced development testing to date of the RCS thruster and the integration with a vehicle propulsion system.

Tuning cofactor redox potentials: the 2-methoxy dihedral angle generates a redox potential difference of >160 mV between the primary (Q(A)) and secondary (Q(B)) quinones of the bacterial photosynthetic reaction center.

Science.gov (United States)

Taguchi, Alexander T; Mattis, Aidas J; O'Malley, Patrick J; Dikanov, Sergei A; Wraight, Colin A

2013-10-15

Only quinones with a 2-methoxy group can act simultaneously as the primary (QA) and secondary (QB) electron acceptors in photosynthetic reaction centers from Rhodobacter sphaeroides. (13)C hyperfine sublevel correlation measurements of the 2-methoxy in the semiquinone states, SQA and SQB, were compared with quantum mechanics calculations of the (13)C couplings as a function of the dihedral angle. X-ray structures support dihedral angle assignments corresponding to a redox potential gap (ΔEm) between QA and QB of ~180 mV. This is consistent with the failure of a ubiquinone analogue lacking the 2-methoxy to function as QB in mutant reaction centers with a ΔEm of ≈160-195 mV.

Standard Gibbs free energies of reactions of ozone with free radicals in aqueous solution: quantum-chemical calculations.

Science.gov (United States)

Naumov, Sergej; von Sonntag, Clemens

2011-11-01

Free radicals are common intermediates in the chemistry of ozone in aqueous solution. Their reactions with ozone have been probed by calculating the standard Gibbs free energies of such reactions using density functional theory (Jaguar 7.6 program). O(2) reacts fast and irreversibly only with simple carbon-centered radicals. In contrast, ozone also reacts irreversibly with conjugated carbon-centered radicals such as bisallylic (hydroxycylohexadienyl) radicals, with conjugated carbon/oxygen-centered radicals such as phenoxyl radicals, and even with nitrogen- oxygen-, sulfur-, and halogen-centered radicals. In these reactions, further ozone-reactive radicals are generated. Chain reactions may destroy ozone without giving rise to products other than O(2). This may be of importance when ozonation is used in pollution control, and reactions of free radicals with ozone have to be taken into account in modeling such processes.

Reaction paths based on mean first-passage times

International Nuclear Information System (INIS)

Park, Sanghyun; Sener, Melih K.; Lu Deyu; Schulten, Klaus

2003-01-01

Finding representative reaction pathways is important for understanding the mechanism of molecular processes. We propose a new approach for constructing reaction paths based on mean first-passage times. This approach incorporates information about all possible reaction events as well as the effect of temperature. As an application of this method, we study representative pathways of excitation migration in a photosynthetic light-harvesting complex, photosystem I. The paths thus computed provide a complete, yet distilled, representation of the kinetic flow of excitation toward the reaction center, thereby succinctly characterizing the function of the system

Mechanism and kinetics in reactions of caffeic acid with radicals by pulse radiolysis and calculation

Energy Technology Data Exchange (ETDEWEB)

Li, Xifeng; Cai, Zhongli; Katsumura, Yosuke [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab

2000-03-01

The interaction of caffeic acid with e{sub aq}{sup -}, (CH{sub 3}){sub 2}(OH) CCH{sub 2}{sup {center_dot}}, CO{sub 2}{sup {center_dot}}{sup -}, H{sup {center_dot}}, {center_dot}OH and N{sub 3}{sup {center_dot}} radicals were studied by {gamma}-, pulse radiolysis and molecular orbital calculation. UV-visible spectra of electron/{center_dot}OH adducts, semi-quinone radicals of caffeic ions, and the stable products from the reactions were derived. The rate constants were determined. The attacked sites and the most favorable structures of the transient radicals were predicted. Reaction mechanisms were proposed. (author)

Conformational differences between the methoxy groups of QA and QB site ubisemiquinones in bacterial reaction centers: a key role for methoxy group orientation in modulating ubiquinone redox potential.

Science.gov (United States)

Taguchi, Alexander T; O'Malley, Patrick J; Wraight, Colin A; Dikanov, Sergei A

2013-07-09

Ubiquinone is an almost universal, membrane-associated redox mediator. Its ability to accept either one or two electrons allows it to function in critical roles in biological electron transport. The redox properties of ubiquinone in vivo are determined by its environment in the binding sites of proteins and by the dihedral angle of each methoxy group relative to the ring plane. This is an attribute unique to ubiquinone among natural quinones and could account for its widespread function with many different redox complexes. In this work, we use the photosynthetic reaction center as a model system for understanding the role of methoxy conformations in determining the redox potential of the ubiquinone/semiquinone couple. Despite the abundance of X-ray crystal structures for the reaction center, quinone site resolution has thus far been too low to provide a reliable measure of the methoxy dihedral angles of the primary and secondary quinones, QA and QB. We performed 2D ESEEM (HYSCORE) on isolated reaction centers with ubiquinones (13)C-labeled at the headgroup methyl and methoxy substituents, and have measured the (13)C isotropic and anisotropic components of the hyperfine tensors. Hyperfine couplings were compared to those derived by DFT calculations as a function of methoxy torsional angle allowing estimation of the methoxy dihedral angles for the semiquinones in the QA and QB sites. Based on this analysis, the orientation of the 2-methoxy groups are distinct in the two sites, with QB more out of plane by 20-25°. This corresponds to an ≈50 meV larger electron affinity for the QB quinone, indicating a substantial contribution to the experimental difference in redox potentials (60-75 mV) of the two quinones. The methods developed here can be readily extended to ubiquinone-binding sites in other protein complexes.

Nuclear reaction studies using inverse kinematics

International Nuclear Information System (INIS)

Shapira, D.

1985-01-01

Reaction studies with reversed kinematics refer to studies of nuclear reactions induced by a heavy projectile colliding with lighter target nuclei. The technique of using reversed kinematics is costly in terms of the available center-of-mass energy. Most of the projectile's energy goes into forward motion of the reaction products in the laboratory system. Examples are presented where the use of reversed kinematics techniques has provided new information on certain reaction processes. A list of kinematic properties and advantages they may afford is shown. Clearly the possible studies listed can be done without using reversed kinematics but because of the difficulty associated with some of these studies they were never performed until more energetic heavier beams have become available and the reversed kinematics technique was utilized

Physical stage of photosynthesis charge separation

Science.gov (United States)

Yakovlev, A. G.; Shuvalov, V. A.

2016-06-01

An analytical review is given concerning the biophysical aspects of light-driven primary charge separation in photosynthesis reaction centers (RCs) which are special pigment-protein complexes residing in a cell membrane. The primary (physical) stage of charge separation occurs in the pico- and femtosecond ranges and consists of transferring an electron along the active A-branch of pigments. The review presents vast factual material on both the general issues of primary photosynthesis and some more specific topics, including (1) the role of the inactive B-branch of pigments, (2) the effect of the protein environment on the charge separation, and (3) the participation of monomeric bacteriochlorophyll BA in primary electron acceptance. It is shown that the electron transfer and stabilization are strongly influenced by crystallographic water and tyrosine M210 molecules from the nearest environment of BA. A linkage between collective nuclear motions and electron transfer upon charge separation is demonstrated. The nature of the high quantum efficiency of primary charge separation reactions is discussed.

TWO RED CLUMPS AND THE X-SHAPED MILKY WAY BULGE

International Nuclear Information System (INIS)

McWilliam, Andrew; Zoccali, Manuela

2010-01-01

From Two Micron All Sky Survey infrared photometry, we find two red clump (RC) populations coexisting in fields toward the Galactic bulge at latitudes |b|>5. 0 5, ranging over ∼13 0 in longitude and 20 0 in latitude. These RC peaks indicate two stellar populations separated by ∼2.3 kpc; at (l, b) = (+1, - 8) the two RCs are located at 6.5 and 8.8 ± 0.2 kpc. The double-peaked RC is inconsistent with a tilted bar morphology. Most of our fields show the two RCs at roughly constant distance with longitude, also inconsistent with a tilted bar; however, an underlying bar may be present. Stellar densities in the two RCs change dramatically with longitude: on the positive longitude side the foreground RC is dominant, while the background RC dominates negative longitudes. A line connecting the maxima of the foreground and background populations is tilted to the line of sight by ∼20 0 ±4 0 , similar to claims for the tilt of a Galactic bar. The distance between the two RCs decreases toward the Galactic plane; seen edge-on the bulge is X-shaped, resembling some extragalactic bulges and the results of N-body simulations. The center of this X is consistent with the distance to the Galactic center, although better agreement would occur if the bulge is 2-3 Gyr younger than 47 Tuc. Our observations may be understood if the two RC populations emanate, nearly tangentially, from the Galactic bar ends, in a funnel shape. Alternatively, the X, or double funnel, may continue to the Galactic center. From the Sun, this would appear peanut/box shaped, but X-shaped when viewed tangentially.

Defect reactions on the phosphorus sublattice in low-temperature electron-irradiated InP

International Nuclear Information System (INIS)

Sibille, A.; Suski, J.

1985-01-01

This Rapid Communication describes several thermally or electronically stimulated defect reactions involving the dominant deep centers in low-temperature (25--300 K) electron-irradiated InP. Some of these reactions result in an increased concentration of the centers, thereby revealing the existence of a secondary production mechanism of the related defects. Low-energy irradiations allows one to select the type of the ejected atom (P) and gives direct evidence that only a phosphorus species, interstitial or vacancy, is involved in the creation-reaction-annealing events

Organolanthanide reagents and the Mukaiyama reaction

International Nuclear Information System (INIS)

Gong, L.

1989-01-01

The bis(pentamethylcyclopentadienyl) lutetium halide complex [(C 5 Me 5 ) 2 LuCl/center dot/THF] was synthesized and characterized. The crystal structure of this complex shows that the Lu is at the center of a distorted tetrahedron consisting of the centroids of two cyclopentadienyl rings, the oxygen atom of a tetrahydrofuran molecule and a chlorine atom. 1 H NMR studies of toluene-d 8 solutions of (C 5 Me 5 LuCl(THF) + THF, (TMS 2 CP) 2 LuCl(THF) + THF, and (MeCp) 2 LuCl(THF) + THF at various temperatures showed exchange processes between co- ordinated THF and free THF with average values of ΔG/sup ne/ of 13.0 /+-/ 0.3 kcal/mol, 11.1 /+-/ 0.1 kcal/mol and 2 Cp) 2 YbCl dimer, silyl enol ethers (R 1 R 2 C = C(OR 3 )OSiMe 3 )) react with benzaldehyde smoothly in dichloromethane at room temperature, giving >99% of the aldol silyl ether (isolated yield: 90%) within 3 h. At /minus/78/degrees/C, the reaction gives kinetically controlled diastereoselectivity, which was not observed in the TiCl 4 -mediated aldol reaction. The use of organoytterbium enolates shows promise result with respect to increased stereoselectivity, and indicates the importance of the bulky ligands on the metal center. In addition, Yb(III) species can retard retroaldol reaction owing to its mild Lewis acidity. 118 refs., 14 figs., 30 tabs

Modeling and analysis of liquid deuterium-water reactions

International Nuclear Information System (INIS)

Taleyarkhan, R.P.

1995-01-01

This Presentation highlights the following: Overview of LD 2 -water reactions their connections to research reactors with cold sources; some key features and ingredients of vapor explosions in general; Examination of results of 1970 experiment at Grenoble Nuclear Research Center; Thermodynamic evaluations of energetics of explosive LD 2 -D 2 O reactions. This presentation concentrates only on the technical aspects of LD 2 /LH 2 - water reactions; it is not intended to draw/imply safety-related conclusions for research reactors

Reaction of giant wheel polyoxomolybdate clusters with ethanol

International Nuclear Information System (INIS)

Bielanski, A.; Malecka-Lubanska, A.; Pozniczek, J.; Mueller, A.; Krickemeyer, E.; Diemann, E.

2001-01-01

The conversion of ethanol at 100-280 o C was used in order to characterise the redox and acid centers present in Na 15 0.5[Mo 152 O 457 H 14 (H 2 O) 68 ]·0.5[Mo 154 O 462 H 14 (H 2 O) 70 ]· ca.400H 2 O (1). It is concluded that Mo V /Mo VI pairs at the external surface of the rings, of which the structure of 1 is composed, are the redox centers active in ethanol dehydrogenation to acetaldehyde. Simultaneous ethanol dehydration to diethyl ether or ethylene is a typical reaction occurring on the acid centers. It is suggested that OH groups situated in (μ 3 -O) 2 O 2 tetrahedrons inside the ring structure play such role, The formation of ethane predominating at highest temperatures is attributed to secondary reactions of primary ethylene. (author)

Detailed analysis of allergic cutaneous reactions to spinal cord stimulator devices

Directory of Open Access Journals (Sweden)

Chaudhry ZA

2013-08-01

Full Text Available Zeshan Ahmed Chaudhry,1 Umer Najib,2 Zahid H Bajwa,3 W Carl Jacobs,4 Javed Sheikh,5 Thomas T Simopoulos61Department of Diagnostic and Interventional Neuroradiology, Massachusetts General Hospital/Harvard Medical School, Boston, MA, USA; 2Department of Neurology, Robert C Byrd Health Sciences Center of West Virginia University, Morgantown, WV, USA; 3Boston Headache Institute, Waltham, MA, USA; 4Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA; 5Department of Medicine, Allergy and Immunology, 6Department of Anesthesia, Beth Israel Deaconess Medical Center, Brookline, MA, USAAbstract: The use of spinal cord stimulation (SCS devices to treat chronic, refractory neuropathic pain continues to expand in application. While device-related complications have been well described, inflammatory reactions to the components of these devices remain underreported. In contrast, hypersensitivity reactions associated with other implanted therapies, such as endovascular and cardiac rhythm devices, have been detailed. The purpose of this case series is to describe the clinical presentation and course of inflammatory reactions as well as the histology of these reactions. All patients required removal of the entire device after developing inflammatory reactions over a time course of 1–3 months. Two patients developed a foreign body reaction in the lead insertion wound as well as at the implantable pulse generator site, with histology positive for giant cells. One patient developed an inflammatory dermatitis on the flank and abdomen that resolved with topical hydrocortisone. “In vivo” testing with a lead extension fragment placed in the buttock resulted in a negative reaction followed by successful reimplantation of an SCS device. Inflammatory reactions to SCS devices can manifest as contact dermatitis, granuloma formation, or foreign body reactions with giant cell formation. Tissue diagnosis is essential, and

Some experiments on the primary electron acceptor in reaction centres from Rhodopseudomanas sphaeroides

Energy Technology Data Exchange (ETDEWEB)

Wraight, C A; Cogdell, R J; Clayton, R K

1975-01-01

The bacterial reaction center absorbance change at 450 nm (A-450), assigned to an anionic semiquinone, has been suggested as a candidate for the reduced form of the primary electron acceptor in bacterial photosynthesis. In reaction centers of Rhodopseudomonas sphaeroides we have found kinetic discrepancies between the decay of A-450 and the recovery of photochemical competence. In addition, no proton uptake is measurable on the first turnover, although subsequent ones elicit one proton bound per electron. These results are taken to indicate that the acceptor reaction after a long dark period may be different for the first turnover than for subsequent ones. It is suggested that A-450 is still a likely candidate for the acceptor function but that in reaction centers, additional quinone may act as an adventitious primary acceptor when the ''true'' primary acceptor is reduced. Alternatively, the primary acceptor may act in a ''ping-pong'' fashion with respect to subsequent photoelectrons.

Adverse reactions and other factors that impact subsequent blood donation visits.

Science.gov (United States)

Custer, Brian; Rios, Jorge A; Schlumpf, Karen; Kakaiya, Ram M; Gottschall, Jerome L; Wright, David J

2012-01-01

The importance of adverse reactions in terms of donor safety recently has received significant attention, but their role in subsequent donation behavior has not been thoroughly investigated. Six REDS-II blood centers provided data for this analysis. Summary minor and major adverse reaction categories were created. The influence of adverse reactions on donation was examined in two ways: Kaplan-Meier curves were generated to determine the cumulative pattern of first return, and adjusted odds ratios (AORs) for demographic and other factors positively and negatively associated with return were estimated using multivariable logistic regression. Donors who had major reactions had longer times to return than donors with minor or no reactions. The AOR of returning for donors with major reactions was 0.32 (95% confidence interval [CI], 0.28-0.37) and with minor reactions 0.59 (95% CI, 0.56-0.62) when compared to donors who did not have reactions. Conversely, the most important factors positively associated with return were the number of donations in the previous year and increasing age. Subsequent return, whether a major, minor, or no reaction occurred, varied by blood center. Factors that are associated with the risk of having adverse reactions were not substantial influences on the return after adverse reactions. Having an adverse reaction leads to significantly lower odds of subsequent donation irrespective of previous donation history. Factors that have been associated with a greater risk of adverse reactions were not important positive or negative predictors of return after a reaction. © 2011 American Association of Blood Banks.

In vitro biocorrosion of Ti-6Al-4V implant alloy by a mouse macrophage cell line.

Science.gov (United States)

Lin, Hsin-Yi; Bumgardner, Joel D

2004-03-15

Corrosion of implant alloys releasing metal ions has the potential to cause adverse tissue reactions and implant failure. We hypothesized that macrophage cells and their released reactive chemical species (RCS) affect the alloy's corrosion properties. A custom cell culture corrosion box was used to evaluate how cell culture medium, macrophage cells and RCS altered the Ti-6Al-4V corrosion behaviors in 72 h and how corrosion products affected the cells. There was no difference in the charge transfer in the presence (75.2 +/- 17.7 mC) and absence (62.3 +/- 18.8 mC) of cells. The alloy had the lowest charge transfer (28.2 +/- 4.1 mC) and metal ion release (Ti < 10 ppb, V < 2 ppb) with activated cells (releasing RCS) compared with the other two conditions. This was attributed to an enhancement of the surface oxides by RCS. Metal ion release was very low (Ti < 20 ppb, V < 10 ppb) with nonactivated cells and did not change cell morphology, viability, and NO and ATP release compared with controls. However, IL-1beta released from the activated cells and the proliferation of nonactivated cells were greater on the alloy than the controls. In summary, macrophage cells and RCS reduced the corrosion of Ti-6Al-4V alloys as hypothesized. These data are important in understanding host tissue-material interactions. Copyright 2004 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 717-724, 2004

Orientations of Iron-Sulfur Clusters FA and FB in the Homodimeric Type-I Photosynthetic Reaction Center of Heliobacterium modesticaldum.

Science.gov (United States)

Kondo, Toru; Matsuoka, Masahiro; Azai, Chihiro; Itoh, Shigeru; Oh-Oka, Hirozo

2016-05-12

Orientations of the FA and FB iron-sulfur (FeS) clusters in a structure-unknown type-I homodimeric heriobacterial reaction center (hRC) were studied in oriented membranes of the thermophilic anaerobic photosynthetic bacterium Heliobacterium modesticaldum by electron paramagnetic resonance (EPR), and compared with those in heterodimeric photosystem I (PS I). The Rieske-type FeS center in the cytochrome b/c complex showed a well-oriented EPR signal. Illumination at 14 K induced an FB(-) signal with g-axes of gz = 2.066, gy = 1.937, and gx = 1.890, tilted at angles of 60°, 60°, and 45°, respectively, with respect to the membrane normal. Chemical reduction with dithionite produced an additional signal of FA(-), which magnetically interacted with FB(-), with gz = 2.046, gy = 1.942, and gx = 1.911 at 30°, 60°, and 90°, respectively. The angles and redox properties of FA(-) and FB(-) in hRC resemble those of FB(-) and FA(-), respectively, in PS I. Therefore, FA and FB in hRC, named after their g-value similarities, seem to be located like FB and FA, not like FA and FB, respectively, in PS I. The reducing side of hRC could resemble those in PS I, if the names of FA and FB are interchanged with each other.

Volume changes and electrostriction in the primary photoreactions of various photosynthetic systems: estimation of dielectric coefficient in bacterial reaction centers and of the observed volume changes with the Drude-Nernst equation.

Science.gov (United States)

Mauzerall, David; Hou, Jian-Min; Boichenko, Vladimir A

2002-01-01

Photoacoustics (PA) allows the determination of enthalpy and volume changes of photoreactions in photosynthetic reaction centers on the 0.1-10 mus time scale. These include the bacterial centers from Rb. sphaeroides, PS I and PS II centers from Synechocystis and in whole cells. In vitro and in vivo PA data on PS I and PS II revealed that both the volume change (-26 A(3)) and reaction enthalpy (-0.4 eV) in PS I are the same as those in the bacterial centers. However the volume change in PS II is small and the enthalpy far larger, -1 eV. Assigning the volume changes to electrostriction allows a coherent explanation of these observations. One can explain the large volume decrease in the bacterial centers with an effective dielectric coefficient of approximately 4. This is a unique approach to this parameter so important in estimation of protein energetics. The value of the volume contraction for PS I can only be explained if the acceptor is the super- cluster (Fe(4)S(4))(Cys(4)) with charge change from -1 to -2. The small volume change in PS II is explained by sub-mus electron transfer from Y(Z) anion to P(680) cation, in which charge is only moved from the Y(Z) anion to the Q(A) with no charge separation or with rapid proton transfer from oxidized Y(Z) to a polar region and thus very little change in electrostriction. At more acid pH equally rapid proton transfer from a neighboring histidine to a polar region may be caused by the electric field of the P(680) cation.

Differences between Drug-Induced and Contrast Media-Induced Adverse Reactions Based on Spontaneously Reported Adverse Drug Reactions.

Science.gov (United States)

Ryu, JiHyeon; Lee, HeeYoung; Suh, JinUk; Yang, MyungSuk; Kang, WonKu; Kim, EunYoung

2015-01-01

We analyzed differences between spontaneously reported drug-induced (not including contrast media) and contrast media-induced adverse reactions. Adverse drug reactions reported by an in-hospital pharmacovigilance center (St. Mary's teaching hospital, Daejeon, Korea) from 2010-2012 were classified as drug-induced or contrast media-induced. Clinical patterns, frequency, causality, severity, Schumock and Thornton's preventability, and type A/B reactions were recorded. The trends among causality tools measuring drug and contrast-induced adverse reactions were analyzed. Of 1,335 reports, 636 drug-induced and contrast media-induced adverse reactions were identified. The prevalence of spontaneously reported adverse drug reaction-related admissions revealed a suspected adverse drug reaction-reporting rate of 20.9/100,000 (inpatient, 0.021%) and 3.9/100,000 (outpatients, 0.004%). The most common adverse drug reaction-associated drug classes included nervous system agents and anti-infectives. Dermatological and gastrointestinal adverse drug reactions were most frequently and similarly reported between drug and contrast media-induced adverse reactions. Compared to contrast media-induced adverse reactions, drug-induced adverse reactions were milder, more likely to be preventable (9.8% vs. 1.1%, p contrast media-induced adverse reactions (56.6%, p = 0.066). Causality patterns differed between the two adverse reaction classes. The World Health Organization-Uppsala Monitoring Centre causality evaluation and Naranjo algorithm results significantly differed from those of the Korean algorithm version II (p contrast media-induced adverse reactions. The World Health Organization-Uppsala Monitoring Centre and Naranjo algorithm causality evaluation afforded similar results.

Electron transfer. 93. Further reactions of transition-metal-center oxidants with vitamin B12s (Cob(I)alamin)

International Nuclear Information System (INIS)

Pillai, G.C.; Ghosh, S.K.; Gould, E.S.

1988-01-01

Vitamin B 12s (cob(I)alamin) reduces europium(III), titanium(IV) (TiO(C 2 O 4 ) 2 2- ), and uranium(VI) in aqueous solution. These oxidants undergo one-electron changes, leading in each case to the cobalt product cob(II)alamin (B 12r ). The reduction of Eu 3+ , which is inhibited by TES buffer, but not by glycine, is outer sphere. Its limiting specific rate (1 x 10 2 M -1 s -1 ), incorporated in the Marcus treatment, yields a B 12s ,B 12r self-exchange rate of 10 4.8±0.5 M -1 s -1 . Reductions of TiO(C 2 O 4 ) 2 2- are accelerated by H + and by acetic acid. Kinetic patterns suggest three competing reaction paths involving varying degrees of protonation of the Ti(IV) center or its association with acetic acid. The very rapid reduction of U(VI) (k = 4 x 10 6 M -1 s -1 ) yields U(V) in several buffering media, even when B 12s is taken in excess. The much slower conversion of U(V) to U(IV), although thermodynamically favored, appears to be retarded by the extensive reorganization of the coordination sphere of oxo-bound U(V) that must accompany its acceptance of an additional electron. The observed specific rate for the B 12s -U(VI) reaction is in reasonable agreement, in the framework of the Marcus formalism, with reported values of the formal potential and the self-exchange rate for U(V,VI). 37 references, 4 tables

Factors controlling the redox potential of ZnCe6 in an engineered bacterioferritin photochemical 'reaction centre'.

Science.gov (United States)

Mahboob, Abdullah; Vassiliev, Serguei; Poddutoori, Prashanth K; van der Est, Art; Bruce, Doug

2013-01-01

Photosystem II (PSII) of photosynthesis has the unique ability to photochemically oxidize water. Recently an engineered bacterioferritin photochemical 'reaction centre' (BFR-RC) using a zinc chlorin pigment (ZnCe6) in place of its native heme has been shown to photo-oxidize bound manganese ions through a tyrosine residue, thus mimicking two of the key reactions on the electron donor side of PSII. To understand the mechanism of tyrosine oxidation in BFR-RCs, and explore the possibility of water oxidation in such a system we have built an atomic-level model of the BFR-RC using ONIOM methodology. We studied the influence of axial ligands and carboxyl groups on the oxidation potential of ZnCe6 using DFT theory, and finally calculated the shift of the redox potential of ZnCe6 in the BFR-RC protein using the multi-conformational molecular mechanics-Poisson-Boltzmann approach. According to our calculations, the redox potential for the first oxidation of ZnCe6 in the BRF-RC protein is only 0.57 V, too low to oxidize tyrosine. We suggest that the observed tyrosine oxidation in BRF-RC could be driven by the ZnCe6 di-cation. In order to increase the efficiency of tyrosine oxidation, and ultimately oxidize water, the first potential of ZnCe6 would have to attain a value in excess of 0.8 V. We discuss the possibilities for modifying the BFR-RC to achieve this goal.

Separate photosensitizers mediate degradation of the 32-kDa photosystem II reaction center protein in the visible and UV spectral regions

International Nuclear Information System (INIS)

Greenberg, B.M.; Gaba, V.; Canaani, O.; Malkin, S.; Mattoo, A.K.; Edelman, M.

1989-01-01

A component of the photosystem II reaction center, the 32-kDa protein, is rapidly turned over in the light. The mechanism of its light-dependent metabolism is largely unknown. We quantified the rate of 32-kDa protein degradation over a broad spectral range (UV, visible, and far red). The quantum yield for degradation was highest in the UVB (280-320 nm) region. Spectral evidence demonstrates two distinctly different photosensitizers for 32-kDa protein degradation. The data implicate the bulk photosynthetic pigments (primarily chlorophyll) in the visible and far red regions, and plastoquinone (in one or more of its redox states) in the UV region. A significant portion of 32-kDa protein degradation in sunlight is attributed to UVB irradiance

Laser Spot Detection Based on Reaction Diffusion

OpenAIRE

Alejandro Vázquez-Otero; Danila Khikhlukha; J. M. Solano-Altamirano; Raquel Dormido; Natividad Duro

2016-01-01

Center-location of a laser spot is a problem of interest when the laser is used for processing and performing measurements. Measurement quality depends on correctly determining the location of the laser spot. Hence, improving and proposing algorithms for the correct location of the spots are fundamental issues in laser-based measurements. In this paper we introduce a Reaction Diffusion (RD) system as the main computational framework for robustly finding laser spot centers. The method presente...

Self-reported adverse reactions among patients initiating antiretroviral therapy in Brazil

Directory of Open Access Journals (Sweden)

Cristiane A. Menezes de Pádua

Full Text Available A cross-sectional analysis was carried out to describe adverse reactions to antiretroviral therapy (ART reported by HIV-infected patients initiating treatment at two public health AIDS referral centers in Belo Horizonte, Brazil, 2001-2003 and to verify their association with selected variables. Adverse reactions were obtained through interview at the first follow-up visit (first month after the antiretroviral prescription. Socio-demographic and behavioral variables related to ART were obtained from baseline and follow-up interviews and clinical variables from medical charts. Patients with four or more reactions were compared to those with less than four. Odds ratio with 95% confidence interval were estimated using logistic regression model for both univariate and multivariate analyses. At least one adverse reaction was reported by 92.2% of the participants while 56.2% reported four or more different reactions. Antiretroviral regimens including indinavir/ritonavir, irregular use of antiretrovirals and switch in regimens were independently associated with four or more adverse reactions (OR=7.92, 5.73 and 2.03, respectively. The initial period of ARV treatment is crucial and patients´ perception of adverse reactions should be carefully taken into account. Strategies for monitoring and management of adverse reactions including the choice of regimens and the prevention of irregular ART should be developed in AIDS/HIV referral centers in Brazil to promote better adherence to antiretroviral therapy.

Efficient free energy calculations by combining two complementary tempering sampling methods.

Science.gov (United States)

Xie, Liangxu; Shen, Lin; Chen, Zhe-Ning; Yang, Mingjun

2017-01-14

Although energy barriers can be efficiently crossed in the reaction coordinate (RC) guided sampling, this type of method suffers from identification of the correct RCs or requirements of high dimensionality of the defined RCs for a given system. If only the approximate RCs with significant barriers are used in the simulations, hidden energy barriers with small to medium height would exist in other degrees of freedom (DOFs) relevant to the target process and consequently cause the problem of insufficient sampling. To address the sampling in this so-called hidden barrier situation, here we propose an effective approach to combine temperature accelerated molecular dynamics (TAMD), an efficient RC-guided sampling method, with the integrated tempering sampling (ITS), a generalized ensemble sampling method. In this combined ITS-TAMD method, the sampling along the major RCs with high energy barriers is guided by TAMD and the sampling of the rest of the DOFs with lower but not negligible barriers is enhanced by ITS. The performance of ITS-TAMD to three systems in the processes with hidden barriers has been examined. In comparison to the standalone TAMD or ITS approach, the present hybrid method shows three main improvements. (1) Sampling efficiency can be improved at least five times even if in the presence of hidden energy barriers. (2) The canonical distribution can be more accurately recovered, from which the thermodynamic properties along other collective variables can be computed correctly. (3) The robustness of the selection of major RCs suggests that the dimensionality of necessary RCs can be reduced. Our work shows more potential applications of the ITS-TAMD method as the efficient and powerful tool for the investigation of a broad range of interesting cases.

Report on the 9. IAEA consultants' meeting of the nuclear reaction data centres

International Nuclear Information System (INIS)

Lemmel, H.D.

1988-04-01

This report summarizes the 1987 co-ordination meeting of the national and regional nuclear reaction data centers, convened by the IAEA at regular intervals. The main topics are: the international exchange of nuclear reaction data by means of the ''EXFOR'' system, and the further development of this system; the ''CINDA'' system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable data compilation; the exchange and documentation of evaluated data libraries in ENDF format, with the goal of rendering data center services to data users in IAEA Member States by means of computer retrievals and printed materials. (author). Refs, figs and tabs

Redox potential tuning through differential quinone binding in the photosynthetic reaction center of Rhodobacter sphaeroides.

Science.gov (United States)

Vermaas, Josh V; Taguchi, Alexander T; Dikanov, Sergei A; Wraight, Colin A; Tajkhorshid, Emad

2015-03-31

Ubiquinone forms an integral part of the electron transport chain in cellular respiration and photosynthesis across a vast number of organisms. Prior experimental results have shown that the photosynthetic reaction center (RC) from Rhodobacter sphaeroides is only fully functional with a limited set of methoxy-bearing quinones, suggesting that specific interactions with this substituent are required to drive electron transport and the formation of quinol. The nature of these interactions has yet to be determined. Through parameterization of a CHARMM-compatible quinone force field and subsequent molecular dynamics simulations of the quinone-bound RC, we have investigated and characterized the interactions of the protein with the quinones in the Q(A) and Q(B) sites using both equilibrium simulation and thermodynamic integration. In particular, we identify a specific interaction between the 2-methoxy group of ubiquinone in the Q(B) site and the amide nitrogen of GlyL225 that we implicate in locking the orientation of the 2-methoxy group, thereby tuning the redox potential difference between the quinones occupying the Q(A) and Q(B) sites. Disruption of this interaction leads to weaker binding in a ubiquinone analogue that lacks a 2-methoxy group, a finding supported by reverse electron transfer electron paramagnetic resonance experiments of the Q(A)⁻Q(B)⁻ biradical and competitive binding assays.

Diagnosing ignition with DT reaction history

International Nuclear Information System (INIS)

Wilson, D. C.; Bradley, P. A.; Herrmann, H. W.; Cerjan, C. J.; Salmonson, J. D.; Spears, B. K.; Hatchet, S. P. II; Glebov, V. Yu.

2008-01-01

A full range DT reaction history of an ignition capsule, from 10 9 to 10 20 neutrons/ns, offers the opportunity to diagnose fuel conditions hundreds of picoseconds before and during burn. The burn history begins with a sharp rise when the first shock reaches the center of the capsule. The level of this jump reflects the combined shock strength and the adiabat of DT fuel. Changes to the four laser pulses driving the capsule implosion which are large enough to degrade the yield make measurable changes to the reaction history. Low mode asymmetries grow during convergence but change the reaction history during the final ∼100 ps. High mode asymmetry or turbulence mixing affects only the reaction history within ∼50 ps of peak burn rate. A capsule with a tritium fuel layer containing a small amount of deuterium (∼1%) creates a reaction history similar to the ignition capsule, but without the final ignition burn. A combination of gas Cerenkov detectors and the neutron temporal diagnostic could be capable of diagnosing the full history of ignition and tritium rich capsules.

Preservation of visual cortical function following retinal pigment epithelium transplantation in the RCS rat using optical imaging techniques.

Science.gov (United States)

Gias, Carlos; Jones, Myles; Keegan, David; Adamson, Peter; Greenwood, John; Lund, Ray; Martindale, John; Johnston, David; Berwick, Jason; Mayhew, John; Coffey, Peter

2007-04-01

The aim of this study was to determine the extent of cortical functional preservation following retinal pigment epithelium (RPE) transplantation in the Royal College of Surgeons (RCS) rat using single-wavelength optical imaging and spectroscopy. The cortical responses to visual stimulation in transplanted rats at 6 months post-transplantation were compared with those from age-matched untreated dystrophic and non-dystrophic rats. Our results show that cortical responses were evoked in non-dystrophic rats to both luminance changes and pattern stimulation, whereas no response was found in untreated dystrophic animals to any of the visual stimuli tested. In contrast, a cortical response was elicited in most of the transplanted rats to luminance changes and in many of those a response was also evoked to pattern stimulation. Although the transplanted rats did not respond to high spatial frequency information we found evidence of preservation in the cortical processing of luminance changes and low spatial frequency stimulation. Anatomical sections of transplanted rat retinas confirmed the capacity of RPE transplantation to rescue photoreceptors. Good correlation was found between photoreceptor survival and the extent of cortical function preservation determined with optical imaging techniques. This study determined the efficacy of RPE transplantation to preserve visual cortical processing and established optical imaging as a powerful technique for its assessment.

Reactive scattering from oriented molecules: The three-center reaction K+ICl --> KI+Cl, KCl+I

Science.gov (United States)

Loesch, H. J.; Möller, J.

1992-12-01

In a crossed molecular beam experiment, we have measured the angular and time-of-flight (TOF) distributions of the products KCl and KI formed in the reaction K+ICl→KI+Cl, KCl+I at an elevated collision energy of Etr=1.64 eV. Employing the brute force method, we have prepared an oriented ICl beam and studied in addition also the orientation dependence of these distributions. The results are (i) KCl is the dominant product, but also KI is substantially formed with a branching ratio of 4:1; (ii) the double differential reaction cross section in the center-of-mass frame (contour maps) indicates that all products are preferentially forward scattered and constrained to the forward hemisphere; (iii) the KCl flux consists of two distinct components which differ markedly in kinetic energy and dependence on the ICl orientation; there are also indications of the existence of two components of KI; (iv) 65%, 84%, and 64% of the available energy is vested into the internal degrees of freedom for the fast, slow component of KCl and KI, respectively; (v) the existence of two components can be rationalized on the basis of the harpooning mechanism where the jumping electron accesses the ground state or one of the low excited states of the ICl- ion and triggers the subsequent explosion of the ion with more or less kinetic energy of the fragments depending on the initially populated state; (vi) the energies released during dissociation of ICl- in the 2Σ ground state and the first 2Π state are ≤0.19 and ≤1.2 eV, respectively; (vii) the fast KCl component features a negative steric effect suggesting favorable product formation for attacks of K to the I end of ICl, the steric effect of the slow KI component is positive, i.e., attacks to the Cl end form products favorably; the other components exhibit no significant steric effect; (viii) the steric effects can be quantitatively rationalized using the same model as mentioned above; (ix) the magnitude of the steric effect suggests a

Studies of nuclear reaction at very low energies

International Nuclear Information System (INIS)

Cecil, F.E.

1992-01-01

The deuteron radiative capture reactions on 2 H, 6 Li and 10 B have been measured between center of mass energies of 20 and 140 keV. Of note is the observation that the gamma ray-to-charged particle branching ratio for the DD reaction appears independent of energy down to a center of mass energy of 20 keV, consistent with some and contrary to other theoretical models. We have investigated the ratio of the reactions D(d,p)T and D(d,n) 3 He down to c.m. energies of 3 keV and the ratio of the reactions 6Li(d,p) 7 Li and 6 LI(d,α) 4 He down to a c.m. energy of 19 keV. The DD reaction ratio is independent of energy while the (d,p) branch of the D- 6 Li evinces a significant enhancement at the lowest measured energies. We have continued our investigation of charged particle production from deuterium-metal systems at a modest level of activity. Noteworthy in this investigation is the observation of 3 MeV protons from deuteron beam loaded Ti and LiD targets subjected to extreme thermal disequilibria. Significant facility improvements were realized during the most recent contract period. Specifically the downstream magnetic analysis system proposed to eliminate beam induced contaminants has been installed and thoroughly tested. This improvement should allow the D(a,γ) 6 Li reaction to be measured in the coming contract period. A scattering chamber required for the measurement of the 7 Li( 3 He,p) 9 Be reaction has been designed, fabricated and installed on the accelerator. A CAMAC based charged particle identification system has been assembled also for use in our proposed measurement of the 7 Li( 3 He, p) 9 Be

Molecular beam studies of reaction dynamics

International Nuclear Information System (INIS)

Lee, Yuan T.

1991-03-01

The major thrust of this research project is to elucidate detailed dynamics of simple elementary reactions that are theoretically important and to unravel the mechanism of complex chemical reactions or photochemical processes that play important roles in many macroscopic processes. Molecular beams of reactants are used to study individual reactive encounters between molecules or to monitor photodissociation events in a collision-free environment. Most of the information is derived from measurement of the product fragment energy, angular, and state distributions. Recent activities are centered on the mechanisms of elementary chemical reactions involving oxygen atoms with unsaturated hydrocarbons, the dynamics of endothermic substitution reactions, the dependence of the chemical reactivity of electronically excited atoms on the alignment of excited orbitals, the primary photochemical processes of polyatomic molecules, intramolecular energy transfer of chemically activated and locally excited molecules, the energetics of free radicals that are important to combustion processes, the infrared-absorption spectra of carbonium ions and hydrated hydronium ions, and bond-selective photodissociation through electric excitation

Molecular beam studies of reaction dynamics

Energy Technology Data Exchange (ETDEWEB)

Lee, Y.T. [Lawrence Berkeley Laboratory, CA (United States)

1993-12-01

The major thrust of this research project is to elucidate detailed dynamics of simple elementary reactions that are theoretically important and to unravel the mechanism of complex chemical reactions or photochemical processes that play important roles in many macroscopic processes. Molecular beams of reactants are used to study individual reactive encounters between molecules or to monitor photodissociation events in a collision-free environment. Most of the information is derived from measurement of the product fragment energy, angular, and state distributions. Recent activities are centered on the mechanisms of elementary chemical reactions involving oxygen atoms with unsaturated hydrocarbons, the dynamics of endothermic substitution reactions, the dependence of the chemical reactivity of electronically excited atoms on the alignment of excited orbitals, the primary photochemical processes of polyatomic molecules, intramolecular energy transfer of chemically activated and locally excited molecules, the energetics of free radicals that are important to combustion processes, the infrared-absorption spectra of carbonium ions and hydrated hydronium ions, and bond-selective photodissociation through electric excitation.

Stellar evolution and the triple-α reactions

International Nuclear Information System (INIS)

Suda, Takuma

2014-01-01

Nuclear reaction rates play a crucial role in the evolution of stars. For low-mass stars, the triple-α reaction controls the helium burning stars in the red giant and asymptotic giant branch (AGB) phase. More importantly, the cross section of the triple-α reaction has a great impact on the helium ignition at the center of the electron degenerate helium core of red giants and on the helium shell flashes of AGB stars. It is to be noted that stellar evolution models are influenced not only by the value of the cross section, but also by the temperature dependence of the reaction rate. In this paper, I present the impact of the triple-α reaction rates on the evolution of low-mass metal-free stars and intermediate-mass AGB stars. According to the previous study, the constraint on the triple-α reaction rate is derived based on stellar evolution theory. It is found that the recent revisions of the rate proposed by nuclear physics calculations satisfy the condition for the ignition of the helium core flash in low-mass stars

Spectral properties of chlorines and electron transfer with their participation in the photosynthetic reaction center of photosystem II

Science.gov (United States)

Shchupak, E. E.; Ivashin, N. V.

2014-02-01

Structural factors that provide localization of excited states and determine the properties of primary donor and acceptor of electron in the reaction center of photosystem II (PSII RC) are studied. The results of calculations using stationary and time-dependent density functional theory indicate an important role of protein environments of chlorophylls PA, PB, BA, and BB and pheophytins HA and HB in the area with a radius of no greater than ≤10 Å in the formation of excitonic states of PSII RC. When the neighboring elements are taken into account, the wavelength of long-wavelength Q y transition of chlorophyll molecules is varied by about 10 nm. The effect is less developed for pheophytin molecules (Δλ ≅ 2 nm). The following elements strongly affect energy of the transition: HisA198 and HisD197 amino-acid residues that serve as ligands of magnesium atoms affect PA and PB, respectively; MetA183 affects PA; MetA172 and MetD198 affect BA; water molecules that are located above the planes of the BA and BB macrocycles form H bonds with carbonyl groups; and phytol chains of PA and PB affect BA, BB, HA, and HB. The analysis of excitonic states, mutual positions of molecular orbitals of electron donors and acceptors, and matrix elements of electron transfer reaction shows that (i) charge separation between BA and HA and PB and BA is possible in the active A branch of cofactors of PSII RC and (ii) electron transfer is blocked at the BB - HB fragment in inactive B branch of PSII RC.

The hard start phenomena in hypergolic engines. Volume 4: The chemistry of hydrazine fuels and nitrogen tetroxide propellant systems

Science.gov (United States)

Miron, Y.; Perlee, H. E.

1974-01-01

The various chemical reactions that occur and that could possibly occur in the RCS engines utilizing hydrazine-type fuel/nitrogen tetroxide propellant systems, prior to ignition (preignition), during combustion, and after combustion (postcombustion), and endeavors to relate the hard-start phenomenon to some of these reactions are discussed. The discussion is based on studies utilizing a variety of experimental techniques and apparatus as well as current theories of chemical reactions and reaction kinetics. The chemical reactions were studied in low pressure gas flow reactors, low temperature homogeneous- and heterogeneous-phase reactors, simulated two-dimensional (2-D) engines, and scaled and full size engines.

Time-reversal asymmetry: polarization and analyzing power in nuclear reactions

International Nuclear Information System (INIS)

Rioux, C.; Roy, R.; Slobodrian, R.J.; Conzett, H.E.

1984-01-01

Measurements of the proton polarization in the reactions 7 Li( 3 He, p vector) 9 Be and 9 Be( 3 He, p vector) 11 B and of the analyzing powers in the inverse reactions, initiated by polarized protons at the same center-of-mass energies, show significant differences. This implies the failure of the polarization-analyzing-power theorem and, prima facie, of time-reversal invariance in these reactions. The reaction 2 H( 3 He, p vector) 4 He and its inverse have also been investigated and show smaller differences. A discussion of instrumental asymmetries is presented

Bibliographies on radiation chemistry: Pt. 12; Rate constants for reactions of nonmetallic inorganic radicals in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Helman, W P; Ross, A B [Notre Dame Univ., IN (USA). Radiation Chemistry Data Center

1990-01-01

Rate constants have been determined by pulse radiolysis, flash photolysis, and other methods, for a wide variety of reactions involving transient radicals in aqueous solution. Reliable rate constants have been established for reactions of radicals from water (e{sub aq}{sup -}, {center dot}H, {center dot}OH/{center dot}O{sup -}) and the data have been tabulated (Buxton, 1988) through 1986. Kinetic data for HO{sub 2}{center dot}/O{sub 2}{center dot}{sup -} were tabulated. (Bielski, 1985) from papers published through 1983. A compilation of rate constants, from the literature through Mid-1987, for other nonmetallic inorganic radicals has also appeared recently (Neta, 1988). Together, these compilations contain rate constants for more than 6,000 different reactions, reported in about 2,000 references. The present bibliography provides a list of relevant references which have been collected since the publication of the above-mentioned compilations. The list contains references received through the end of December, 1989. (author).

EXFOR systems manual: Nuclear reaction data exchange format. Revision 97/1

International Nuclear Information System (INIS)

McLane, V.

1997-07-01

This document describes EXFOR, the exchange format designed to allow transmission of nuclear reaction data between the members of the Nuclear Data Center Network. In addition to storing the data and its' bibliographic information, experimental information, including source of uncertainties, is also compiled. The status and history of the data set is also included, e.g., the source of the data, any updates which have been made, and correlations to other data sets. EXFOR is designed for flexibility rather than optimization of data processing in order to meet the diverse needs of the nuclear reaction data centers. The exchange format should not be confused with a center-to-user format. Although users may obtain data from the centers in the EXFOR format, other center-to-user formats have been developed to meet the needs of the users within each center's own sphere of responsibility. The exchange format, as outlined, is designed to allow a large variety of numerical data tables with explanatory and bibliographic information to be transmitted in an easily machine-readable format (for checking and indicating possible errors) and a format that can be read by personnel (for passing judgment on and correcting any errors indicated by the machine)

Clinical Investigation Program RCS-MED-300(R1).

Science.gov (United States)

1984-09-30

Auditory Processing Ability of Children....... 236 Work Unit No. 82/43 (FY82,O) (P) Adolescent Immunity to Varicella and Cytomegalovirus.. .... .... 238...GB: Neonatal intensive care at Fitzsimons Army Medical Center. Military Medicine 149:555-560, 1984. Schydlower M, Lampe RM: Varicella and herpes...gastrointestinal bleeding. Presented at the Amer College of Surgeons, New Mexico Chapter, Las Cruces, NM, June 1984. *Graham GD, Lundy MM, Frederick RJ

Bacteria community study of combined periodontal-endodontic lesions using denaturing gradient gel electrophoresis and sequencing analysis.

Science.gov (United States)

Li, Hong; Guan, Rui; Sun, Jinghua; Hou, Benxiang

2014-10-01

The entire microbial population and predominant microflora of root canals (RCs) and adjacent periodontal pockets (PPs) from teeth with combined periodontal-endodontic lesions were determined and compared. Pooled RC and PP samples were collected from the molars of 20 patients diagnosed with combined periodontal-endodontic lesions. DNA was extracted for polymerase chain reaction-based denaturing gradient gel electrophoresis (PCR-DGGE), cloning, and sequence analysis. A coefficient of similarity (Cs) was used to determine the similarity of the bacterial profiles from RCs and PPs. Significantly fewer bands were produced by PCR-DGGE from RCs (5.9 ± 1.7) than from PPs (8.0 ± 1.8) (P bacteria in both the RC and PP samples were (in descending order) Filifactor alocis, Parvimonas micra, Porphyromonas gingivalis, and Tannerella forsythia. The high similarity in the sets of organisms present in both RC and PP samples in this study suggests that the pocket could be a source of RC infection. The data also demonstrate that combined periodontal-endodontic lesions consist of a diverse and complex microbial community.

The probability of containment failure by direct containment heating in surry

International Nuclear Information System (INIS)

Pilch, M.M.; Allen, M.D.; Bergeron, K.D.; Tadios, E.L.; Stamps, D.W.; Spencer, B.W.; Quick, K.S.; Knudson, D.L.

1995-05-01

In a light-water reactor core melt accident, if the reactor pressure vessel (RPV) fails while the reactor coolant system (RCS) at high pressure, the expulsion of molten core debris may pressurize the reactor containment building (RCB) beyond its failure pressure. A failure in the bottom head of the RPV, followed by melt expulsion and blowdown of the RCS, will entrain molten core debris in the high-velocity steam blowdown gas. This chain of events is called a high-pressure melt ejection (HPME). Four mechanisms may cause a rapid increase in pressure and temperature in the reactor containment: (1) blowdown of the RCS, (2) efficient debris-to-gas heat transfer, (3) exothermic metal-steam and metal-oxygen reactions, and (4) hydrogen combustion. These processes, which lead to increased loads on the containment building, are collectively referred to as direct containment heating (DCH). It is necessary to understand factors that enhance or mitigate DCH because the pressure load imposed on the RCB may lead to early failure of the containment

Reactions of guanine with methyl chloride and methyl bromide: O6-methylation versus charge transfer complex formation

Science.gov (United States)

Shukla, P. K.; Mishra, P. C.; Suhai, S.

Density functional theory (DFT) at the B3LYP/6-31+G* and B3LYP/AUG-cc-pVDZ levels was employed to study O6-methylation of guanine due to its reactions with methyl chloride and methyl bromide and to obtain explanation as to why the methyl halides cause genotoxicity and possess mutagenic and carcinogenic properties. Geometries of the various isolated species involved in the reactions, reactant complexes (RCs), and product complexes (PCs) were optimized in gas phase. Transition states connecting the reactant complexes with the product complexes were also optimized in gas phase at the same levels of theory. The reactant complexes, product complexes, and transition states were solvated in aqueous media using the polarizable continuum model (PCM) of the self-consistent reaction field theory. Zero-point energy (ZPE) correction to total energy and the corresponding thermal energy correction to enthalpy were made in each case. The reactant complexes of the keto form of guanine with methyl chloride and methyl bromide in water are appreciably more stable than the corresponding complexes involving the enol form of guanine. The nature of binding in the product complexes was found to be of the charge transfer type (O6mG+ · X-, X dbond Cl, Br). Binding of HCl, HBr, and H2O molecules to the PCs obtained with the keto form of guanine did not alter the positions of the halide anions in the PCs, and the charge transfer character of the PCs was also not modified due to this binding. Further, the complexes obtained due to the binding of HCl, HBr, and H2O molecules to the PCs had greater stability than the isolated PCs. The reaction barriers involved in the formation of PCs were found to be quite high (?50 kcal/mol). Mechanisms of genotoxicity, mutagenesis and carcinogenesis caused by the methyl halides appear to involve charge transfer-type complex formation. Thus the mechanisms of these processes involving the methyl halides appear to be quite different from those that involve the

On the sub-maximal yield and photo-electric stimulation of chlorophyll a fluorescence in single turnover excitations in plant cells

NARCIS (Netherlands)

Vredenberg, W.J.; Rensen, van J.J.S.; Rodrigues, G.C.

2006-01-01

A set of expressions is derived which quantifies the chlorophyll fluorescence yield in terms of rate constants of primary light reactions of PSII, the fraction of open and semi-open RCs and of the electric field sensed by the RC in the thylakoid membrane. The decay kinetics of the chlorophyll

Chalcogenide metal centers for oxygen reduction reaction: Activity and tolerance

International Nuclear Information System (INIS)

Feng Yongjun; Gago, Aldo; Timperman, Laure; Alonso-Vante, Nicolas

2011-01-01

This mini-review summarizes materials design methods, oxygen reduction kinetics, tolerance to small organic molecules and fuel cell performance of chalcogenide metal catalysts, particularly, ruthenium (Ru x Se y ) and non-precious transition metals (M x X y : M = Co, Fe and Ni; X = Se and S). These non-platinum catalysts are potential alternatives to Pt-based catalysts because of their comparable catalytic activity (Ru x Se y ), low cost, high abundance and, in particular, a high tolerance to small organic molecules. Developing trends of synthesis methods, mechanism of oxygen reduction reaction and applications in direct alcohol fuel cells as well as the substrate effect are highlighted.

Reactions of carbonate radical with cobalt(II) aminopolycarboxylates

International Nuclear Information System (INIS)

Mandal, P.C.; Bardhan, D.K.; Bhattacharyya, S.N.

1992-01-01

Reactions of carbonate (CO 3 - radical) and bicarbonate (HCO 3 radical) radicals generated by photolysis of a carbonate or bicarbonate solution at pH 11.2 and 8.5, respectively, with Co(II) complexes of iminodiacetic acid (IDA) and ethylenediaminetetraacetic acid (EDTA) have been studied. The rate constants for the reactions were in the order of 10 6 -10 7 dm 3 mol -1 s -1 . From the time-resolved spectroscopy of the products formed after reaction of CO 3 - radical or HCO 3 radical, it is observed that CO 3 - radical or HCO 3 radical oxidize the metal center to its higher oxidation state. (author) 26 refs.; 2 figs.; 1 tab

National Nuclear Data Center status report

International Nuclear Information System (INIS)

2002-01-01

This paper is the status report of the US National Nuclear Data Center, Brookhaven. It describes the new NDS approach to customer services, which is based on users initiating wish lists on topics of interest with the possibility to receive reports in hardcopy or electronically forms. After completion within the next two years of the multi platform software for management and data retrievals from shared databases, users will have the opportunity to install directly their own local nuclear data center for desktop applications. The paper describes the computer facilities, the nuclear reaction data structure, the database migration and the customer services. (a.n.)

Reaction intermediates in the catalytic Gif-type oxidation from nuclear inelastic scattering

Energy Technology Data Exchange (ETDEWEB)

Rajagopalan, S., E-mail: rajagopalan78@hotmail.com [Indira Gandhi Centre for Atomic Research, Materials Science Group (India); Asthalter, T., E-mail: t.asthalter@web.de [Universität Stuttgart, Institute of Physical Chemistry (Germany); Rabe, V.; Laschat, S. [Universität Stuttgart, Institute of Organic Chemistry (Germany)

2016-12-15

Nuclear inelastic scattering (NIS) of synchrotron radiation, also known as nuclear resonant vibrational spectroscopy (NRVS), has been shown to provide valuable insights into metal-centered vibrations at Mössbauer-active nuclei. We present a study of the iron-centered vibrational density of states (VDOS) during the first step of the Gif-type oxidation of cyclohexene with a novel trinuclear Fe{sub 3}(μ{sub 3}-O) complex as catalyst precursor. The experiments were carried out on shock-frozen solutions for different combinations of reactants: Fe{sub 3}(μ{sub 3}-O) in pyridine solution, Fe{sub 3}(μ{sub 3}-O) plus Zn/acetic acid in pyridine without and with addition of either oxygen or cyclohexene, and Fe{sub 3}(μ{sub 3}-O)/Zn/acetic acid/pyridine/cyclohexene (reaction mixture) for reaction times of 1 min, 5 min, and 30 min. The projected VDOS of the Fe atoms was calculated on the basis of pseudopotential density functional calculations. Two possible reaction intermediates were identified as [Fe{sup (III)}(C{sub 5}H{sub 5}N){sub 2}(O{sub 2}CCH{sub 3}){sub 2}]{sup +} and Fe{sup (II)}(C{sub 5}H{sub 5}N){sub 4}(O{sub 2}CCH{sub 3}){sub 2}, yielding evidence that NIS (NRVS) allows to identify the presence of iron-centered intermediates also in complex reaction mixtures.

Unifying principles in homodimeric type I photosynthetic reaction centers: properties of PscB and the FA, FB and FX iron-sulfur clusters in green sulfur bacteria.

Science.gov (United States)

Jagannathan, Bharat; Golbeck, John H

2008-12-01

The photosynthetic reaction center from the green sulfur bacterium Chlorobium tepidum (CbRC) was solubilized from membranes using Triton X-100 and isolated by sucrose density ultra-centrifugation. The CbRC complexes were subsequently treated with 0.5 M NaCl and ultrafiltered over a 100 kDa cutoff membrane. The resulting CbRC cores did not exhibit the low-temperature EPR resonances from FA- and FB- and were unable to reduce NADP+. SDS-PAGE and mass spectrometric analysis showed that the PscB subunit, which harbors the FA and FB clusters, had become dissociated, and was now present in the filtrate. Attempts to rebind PscB onto CbRC cores were unsuccessful. Mössbauer spectroscopy showed that recombinant PscB contains a heterogeneous mixture of [4Fe-4S]2+,1+ and other types of Fe/S clusters tentatively identified as [2Fe-2S]2+,1+ clusters and rubredoxin-like Fe3+,2+ centers, and that the [4Fe-4S]2+,1+ clusters which were present were degraded at high ionic strength. Quantitative analysis confirmed that the amount of iron and sulfide in the recombinant protein was sub-stoichiometric. A heme-staining assay indicated that cytochrome c551 remained firmly attached to the CbRC cores. Low-temperature EPR spectroscopy of photoaccumulated CbRC complexes and CbRC cores showed resonances between g=5.4 and 4.4 assigned to a S=3/2 ground spin state [4Fe-4S]1+ cluster and at g=1.77 assigned to a S=1/2 ground spin state [4Fe-4S]1+ cluster, both from FX-. These results unify the properties of the acceptor side of the Type I homodimeric reaction centers found in green sulfur bacteria and heliobacteria: in both, the FA and FB iron-sulfur clusters are present on a salt-dissociable subunit, and FX is present as an interpolypeptide [4Fe-4S]2+,1+ cluster with a significant population in a S=3/2 ground spin state.

Alpha resonant scattering for astrophysical reaction studies

International Nuclear Information System (INIS)

Yamaguchi, H.; Kahl, D.; Nakao, T.; Wakabayashi, Y.; Kubano, S.; Hashimoto, T.; Hayakawa, S.; Kawabata, T.; Iwasa, N.; Teranishi, T.; Kwon, Y. K.; Binh, D. N.; Khiem, L. H.; Duy, N. G.

2014-01-01

Several alpha-induced astrophysical reactions have been studied at CRIB (CNS Radioactive Ion Beam separator), which is a low-energy RI beam separator at Center for Nuclear Study (CNS) of the University of Tokyo. One of the methods to study them is the α resonant scattering using the thick-target method in inverse kinematics. Among the recent studies at CRIB, the measurement of 7 Be+α resonant scattering is discussed. Based on the result of the experiment, we evaluated the contributions of high-lying resonances for the 7 Be(α,γ) reaction, and proposed a new cluster band in 11 C

Clinical Investigation Program Report, RCS MED-300 (R-1).

Science.gov (United States)

1985-10-31

Application of Screening Procedure to Determine the Etiology of Microcytosis with or without Anemia . (T) 150 1983 Remarried Families, Adaptability and...Hospital Militar Central, Lima, Peru ; Naval Hospital, Lima, Peru , 16 May 1985. Gregory GA: Spectrum of disorders in combat reactions. Hospital Militar...Central, Lima, Peru ; Naval Hospital, Lima, Peru , 23 May 1985. Gregory GAs Motivation for combat. Hospital Militar Central, Lima, Peru ; Naval Hospital

Nonelastic nuclear reactions induced by light ions with the BRIEFF code

CERN Document Server

Duarte, H

2010-01-01

The intranuclear cascade (INC) code BRIC has been extended to compute nonelastic reactions induced by light ions on target nuclei. In our approach the nucleons of the incident light ion move freely inside the mean potential of the ion in its center-of-mass frame while the center-of-mass of the ion obeys to equations of motion dependant on the mean nuclear+Coulomb potential of the target nucleus. After transformation of the positions and momenta of the nucleons of the ion into the target nucleus frame, the collision term between the nucleons of the target and of the ion is computed taking into account the partial or total breakup of the ion. For reactions induced by low binding energy systems like deuteron, the Coulomb breakup of the ion at the surface of the target nucleus is an important feature. Preliminary results of nucleon production in light ion induced reactions are presented and discussed.

Redox reactions of tocopherol monoglucoside in aqueous solutions. A pulse radiolysis study

Energy Technology Data Exchange (ETDEWEB)

Kapoor, S.; Mukherjee, T.; Nair, C.K.K. [Bhabha Atomic Research Centre, Mumbai (India); Kagiya, Tsutomu V. [Health Research Foundation, Kyoto (Japan)

2002-03-01

The reactions between tocopherol monoglucoside (TMG), a water-soluble vitamin-E derivative, with Br{sub 2}{sup {center_dot}}{sup -}, N{sub 3}{sup {center_dot}}, (SCN){sub 2}{sup {center_dot}}{sup -}, NO{sub 2}{sup {center_dot}}, OH{sup {center_dot}} and various halogenated peroxyl radicals were examined using a pulse radiolysis technique. The results demonstrate that TMG forms a stable phenoxyl radical at pH>6.8. The thus-formed phenoxyl radical shows pH-dependent decay kinetics and is disproportionated by 2nd order kinetics at pH2.3. It was observed that the TMG reactivity towards a halogenated peroxyl radical increases with the number of halogen atoms at the carbon atom having a peroxyl group. The reaction between the TMG phenoxyl radical and ascorbic acid was also examined using a pulse radiolysis technique. The results indicate that the TMG phenoxyl radical is repaired by ascorbate. Kinetic studies indicate that TMG may act as an antioxidant to repair free-radical damage to some biologically importnat compounds. The one-electron reduction potential for TMG was found to be 0.522 V{+-}0.06 vs. NHE. (author)

Transfusion reactions in pediatric compared with adult patients: a look at rate, reaction type, and associated products.

Science.gov (United States)

Oakley, Fredrick D; Woods, Marcella; Arnold, Shanna; Young, Pampee P

2015-03-01

The majority of reports on transfusion reactions address adult patients. Less is known about the types, incidence, and other clinical details of transfusion reactions in pediatric populations. Furthermore, to our knowledge, there have been no previous reports directly comparing these aspects between adults and pediatric patient populations to assess if there are differences. Between the period of January 1, 2011, and February 1, 2013, all reported adult and pediatric transfusion reactions at Vanderbilt University Medical Center (VUMC) were evaluated by transfusion medicine clinical service. The information was subsequently shared with the hemovigilance database. Data provided to hemovigilance included age, sex, blood product associated with the reaction, severity of the reaction, and the type of transfusion reactions. These were collated with hospital and blood bank information system-acquired data on overall admission and product transfusion. A total of 133,671 transfusions were performed at VUMC during the study period including 20,179 platelet (PLT) transfusions, 31,605 plasma transfusions, 79,933 red blood cell (RBC) transfusions, and 2154 cryoprecipitate transfusions. Over the same period, 108 pediatric and 277 adult transfusion reactions were recorded. This corresponds to an incidence of 6.2 reactions per 1000 transfusions within the pediatric (age reactions per 1000 transfusions within the adult population. In both adult and pediatric populations, transfusion reactions were most commonly associated with PLT, followed by RBC, and then plasma transfusions. Within the pediatric population, subset analysis identified multiple differences when compared to the adult population, including an increased incidence of allergic transfusion reactions (2.7/1000 vs. 1.1/1000, p reactions (1.9/1000 vs. 0.47/1000, p reactions (0.29/1000 vs. 0.078/1000, p reaction incidence was the same between sexes in adults, in pediatric patients, reactions were more common in male

Impact of coronary collaterals on in-hospital and 5-year mortality after ST-elevation myocardial infarction in the contemporary percutaneous coronary intervention era: a prospective observational study

Science.gov (United States)

Hara, Masahiko; Sakata, Yasuhiko; Nakatani, Daisaku; Suna, Shinichiro; Nishino, Masami; Sato, Hiroshi; Kitamura, Tetsuhisa; Nanto, Shinsuke; Hori, Masatsugu; Komuro, Issei

2016-01-01

Objectives To evaluate the short-term and long-term prognostic impacts of acute phase coronary collaterals to occluded infarct-related arteries (IRA) after ST-elevation myocardial infarction (STEMI) in the percutaneous coronary intervention (PCI) era. Design A prospective observational study. Setting Osaka Acute Coronary Insufficiency Study (OACIS) in Japan. Participants 3340 patients with STEMI from the OACIS database who were admitted to hospitals within 24 hours from the onset and who had a completely occluded IRA. Interventions Patients were divided into 4 groups according to the Rentrop collateral score (RCS) by angiography on admission (RCS-0, no visible collaterals; RCS-1, collaterals without IRA filling; RCS-2, collaterals with partial IRA filling; and RCS-3, collaterals with complete IRA filling). Primary outcome measures In-hospital and 5-year mortality. Results Patients with RCS-0/3 were older than patients with RCS-1/2, and the prevalence of previous myocardial infarction was highest in patients with RCS-3. Median peak creatinine phosphokinase levels decreased as RCS increases (p<0.001), suggesting the acute cardioprotective effects of collaterals. Although RCS-1 and RCS-2 collaterals were associated with better in-hospital mortality (adjusted OR 0.48, p=0.046 and 0.38, p=0.010 for RCS-1 and RCS-2, respectively) and 5-year mortality (adjusted HR 0.53, p=0.004 and 0.46, p<0.001 for RCS-1 and RCS-2, respectively) as compared with R-0, presence of RCS-3 collaterals was not associated with improved in-hospital (adjusted OR 1.35, p=0.331) and 5-year mortality (adjusted HR 0.98, p=0.920), possibly because worse clinical profiles in patients with RCS-3 may mask mortality benefit of coronary collaterals. Conclusions Presence of acute phase coronary collaterals such as RCS-1 and RCS-2 were associated with better in-hospital and 5-year mortality after STEMI in the contemporary PCI era. PMID:27412101

Redox reactions of 2-hydroxy-3-methoxybenzaldehyde (o-vanillin) in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Barik, A; Priyadarsini, K I; Mohan, Hari

2004-08-01

Pulse radiolysis technique has been employed to study the reactions of oxidizing ({sup {center_dot}}OH, N{sub 3}{sup {center_dot}}) and reducing radicals (e{sup -}{sub aq}, CO{sub 2}{sup {center_dot}}{sup -}, acetone ketyl radical) with 2-hydroxy-3-methoxybenzaldehyde (o-vanillin) at different pH. Hydroxyl radicals react mostly by addition reaction forming radical adducts ({lambda}{sub max}=420 nm) and the oxidation is only a minor process even in the alkaline region. The reaction with azide radicals produced phenoxyl radicals ({lambda}{sub max}=340 nm), which are formed on fast deprotonation of solute radical cation. Using PMZ{sup {center_dot}}{sup +}/PMZ and ABTS{sup {center_dot}}{sup -}/ABTS{sup 2-} as the reference couple, different methods are employed to determine the one-electron reduction potential of o-vanillin and the average value is estimated to be 1.076{+-}0.004 V vs. NHE at pH 6. The phenoxyl radicals of o-vanillin were able to oxidize ABTS{sup 2-} quantitatively. The e{sub aq}{sup -} is observed to react with o-vanillin with rate constant value of 2x10{sup 10} dm{sup 3} mol{sup -1} s{sup -1}. CO{sub 2}{sup {center_dot}}{sup -} and acetone ketyl radical are also observed to react with o-vanillin by electron transfer mechanism and showed the formation of transient absorption bands with {lambda}{sub max} at 350 and 390 nm at pH 4.5 and 9.7, respectively. The pK{sub a} of the one-electron reduced species was determined to be 8.1. The results indicate that the aldehydic group is the most preferred site for electron addition.

Large area isotopic silicon targets for astrophysical reaction rate studies in Si-26

NARCIS (Netherlands)

Greene, JP; Berg, GPA

2005-01-01

For measurements of stellar reaction rates of proton rich nuclei involving resonance levels just above threshold, targets of Si-28 were used in studies of the Si-21(He-4, He-6)Si-26 reaction using the Research Center for Nuclear Physics (RCNP) Ring Cyclotron at Osaka University. Resonance structure

Combustion Synthesis Reaction Behavior of Cold-Rolled Ni/Al and Ti/Al Multilayers

Science.gov (United States)

2011-04-01

reaction modes of the films. Anselmi-Tamburini and Munir (21) studied the 2 SHS reaction in laminated Ni/Al foils and established a sequence of... convolution of three peaks. The very large broad peak, centered on position C, contains a superimposed peak appearing as a shoulder (position A) and a

Electron transfer reactions of macrocyclic compounds of cobalt

Energy Technology Data Exchange (ETDEWEB)

Heckman, R.A.

1978-08-01

The kinetics and mechanisms of reduction of H/sub 2/O/sub 2/, Br/sub 2/, and I/sub 2/ by various macrocyclic tetraaza complexes of cobalt(II), including Vitamin B/sub 12r/, were studied. The synthetic macrocycles studied were all 14-membered rings which varied in the degree of unsaturation,substitution of methyl groups on the periphery of the ring, and substitution within the ring itself. Scavenging experiments demonstrated that the reductions of H/sub 2/O/sub 2/ produce free hydroxyl radicals only in the case of Co((14)ane)/sup 2 +/ but with none of the others. In the latter instances apparently H/sub 2/O/sub 2/ simultaneously oxidizes the metal center and the ligand. The reductions of Br/sub 2/ and I/sub 2/ produce an aquohalocobalt(III) product for all reductants (except B/sub 12r/ + Br/sub 2/, which was complicated by bromination of the corrin ring). The mechanism of halogen reduction was found to involve rate-limiting inner-sphere electron transfer from cobalt to halogen to produce a dihalide anion coordinated to the cobalt center. This intermediate subsequently decomposes in rapid reactions to halocobalt(III) and halogen atom species or reacts with another cobalt(II) center to give two molecules of halocobalt(III). The reductions of halomethylcobaloximes and related compounds and diamminecobaloxime by Cr/sup 2 +/ were also studied. The reaction was found to be biphasic in all cases with the reaction products being halomethane (for the halomethylcobaloximes), Co/sup 2 +/ (in less than 100 percent yield), a Cr(III)-dimethylglyoxime species, a small amount of free dmgH/sub 2/, and a highly-charged species containing both cobalt and chromium. The first-stage reaction occurs with a stoichiometry of 1:1 producing an intermediate with an absorption maximum at 460 nm for all starting reagents. The results were interpreted in terms of inner-sphere coordination of the cobaloxime to the Cr(II) and electron transfer through the oxime N-O bond.

Angular distribution and cross section measurement for 64Zn(n,α)61Ni reaction

International Nuclear Information System (INIS)

Yuan Jing; Chen Zemin; Dledenov, Y.M.; Sedysheva, M.; Khuuknenkhuu, G.

2001-01-01

Using a gridded ionization chamber, the differential cross section for 64 Zn(n,α) 61 Ni reaction was measured at 5.0, 5.7 and 6.7 MeV. The neutrons were produced through D(d,n) 3 He reaction. Absolute neutron flux was determined through 238 U(n,f) reaction. The results show obviously backward peak in the center of mass reference system

Nuclear information services at the National Nuclear Data Center

International Nuclear Information System (INIS)

Burrows, T.W.; Tuli, J.K.

1996-01-01

The numeric and bibliographic nuclear data bases maintained by the National Nuclear Data Center and access to these data bases will be described. The U.S. Nuclear Data and Reaction Data Networks will also be briefly described

Alpha resonant scattering for astrophysical reaction studies

Energy Technology Data Exchange (ETDEWEB)

Yamaguchi, H.; Kahl, D.; Nakao, T. [Center for Nuclear Study (CNS), University of Tokyo, RIKEN campus, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Wakabayashi, Y.; Kubano, S. [The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Hashimoto, T. [Research Center for Nuclear Physics (RCNP), Osaka University, 10-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Hayakawa, S. [Istituto Nazionale Fisica Nucleare - Laboratori Nazionali del Sud (INFN-LNS), Via S. Sofia 62, 95125 Catania (Italy); Kawabata, T. [Department of Physics, Kyoto University, Kita-Shirakawa, Kyoto 606-8502 (Japan); Iwasa, N. [Department of Physics, Tohoku University, Aoba, Sendai, Miyagi 980-8578 (Japan); Teranishi, T. [Department of Physics, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581 (Japan); Kwon, Y. K. [Institute for Basic Science, 70, Yuseong-daero 1689-gil, Yuseong-gu, Daejeon 305-811 (Korea, Republic of); Binh, D. N. [30 MeV Cyclotron Center, Tran Hung Dao Hospital, Hoan Kiem District, Hanoi (Viet Nam); Khiem, L. H.; Duy, N. G. [Institute of Physics, Vietnam Academy of Science and Technology, 18 Hong Quoc Viet, Nghia do, Hanoi (Viet Nam)

2014-05-02

Several alpha-induced astrophysical reactions have been studied at CRIB (CNS Radioactive Ion Beam separator), which is a low-energy RI beam separator at Center for Nuclear Study (CNS) of the University of Tokyo. One of the methods to study them is the α resonant scattering using the thick-target method in inverse kinematics. Among the recent studies at CRIB, the measurement of {sup 7}Be+α resonant scattering is discussed. Based on the result of the experiment, we evaluated the contributions of high-lying resonances for the {sup 7}Be(α,γ) reaction, and proposed a new cluster band in {sup 11}C.

Calculation of Collective Variable-based PMF by Combining WHAM with Umbrella Sampling

International Nuclear Information System (INIS)

Xu Wei-Xin; Li Yang; Zhang, John Z. H.

2012-01-01

Potential of mean force (PMF) with respect to localized reaction coordinates (RCs) such as distance is often applied to evaluate the free energy profile along the reaction pathway for complex molecular systems. However, calculation of PMF as a function of global RCs is still a challenging and important problem in computational biology. We examine the combined use of the weighted histogram analysis method and the umbrella sampling method for the calculation of PMF as a function of a global RC from the coarse-grained Langevin dynamics simulations for a model protein. The method yields the folding free energy profile projected onto a global RC, which is in accord with benchmark results. With this method rare global events would be sufficiently sampled because the biased potential can be used for restricting the global conformation to specific regions during free energy calculations. The strategy presented can also be utilized in calculating the global intra- and intermolecular PMF at more detailed levels. (cross-disciplinary physics and related areas of science and technology)

Proposals for implementation of methodological aspects in the use of 18F-FDG in the Positron Emission Tomography

International Nuclear Information System (INIS)

Oliveira, Cássio Miri

2013-01-01

This work covered three objectives: to evaluate and implement methods for in vivo internal occupational monitoring of individuals involved during the 18 F-FDG process production; to suggest a national Diagnostic Reference Level (DRL) for 18 F-FDGPET oncologic procedures; and to obtain the 'Recovery Coefficients' (RCs) factors used to correct the radiopharmaceutical uptake in region of interest for a better quantification and evaluation of images. The methodology of internal monitoring was implemented in the radiopharmaceuticals production centers of Nuclear Technology Development Center (CDTN) in Belo Horizonte - MG and the Nuclear Science Regional Center, North-East (CRCN-NE) in Recife, PE, Brazil. The results demonstrated that the developed methodology was efficient to evaluate 18 F-FDG incorporations in both centers; additionally, the methodology showed that there was possibility of 18 F incorporation in the form of 18 F-FDG during non-routine actions performed in the radiopharmaceutical production process. DRLs were suggested based on a questionnaire that was used for the survey of 18 F-FDG administered activity in 72 Brazilian clinics currently licensed by the National Nuclear Energy Commission (CNEN). The results reported by 41 (57%) of the 18 F-FDG-PET clinics showed variations up to 100% in the administered activities among clinics for the same procedure. The calculated DRL from the third quartile was 5.54 MBq/kg or 387.7 MBq (for a 70 kg standard patient). For image analysis, two phantoms were used for obtaining the RCs, the NEMA/IEC Body Phantom, which has spherical capture areas and the modified Jaszczak, which has cylindrical capitation capture areas. Both phantoms were tested for different lesion:BG activity ratios, in the amount of 4:1 and 10:1; for different acquisition time. RCs obtained according to NEMA and IEC standards were applied to the SUVmax and SUVmed semi quantification tools. Values of SUVmed corrected by RCs presented

Proposals for implementation of methodological aspects in the use of {sup 18}F-FDG in the Positron Emission Tomography; Propostas de implementações de aspectos metodológicos na utilização do {sup 18}F-FDG na Tomografia Por Emissão de Pósitron

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Cássio Miri

2013-07-01

This work covered three objectives: to evaluate and implement methods for in vivo internal occupational monitoring of individuals involved during the {sup 18}F-FDG process production; to suggest a national Diagnostic Reference Level (DRL) for {sup 18}F-FDGPET oncologic procedures; and to obtain the 'Recovery Coefficients' (RCs) factors used to correct the radiopharmaceutical uptake in region of interest for a better quantification and evaluation of images. The methodology of internal monitoring was implemented in the radiopharmaceuticals production centers of Nuclear Technology Development Center (CDTN) in Belo Horizonte - MG and the Nuclear Science Regional Center, North-East (CRCN-NE) in Recife, PE, Brazil. The results demonstrated that the developed methodology was efficient to evaluate {sup 18}F-FDG incorporations in both centers; additionally, the methodology showed that there was possibility of {sup 18}F incorporation in the form of {sup 18}F-FDG during non-routine actions performed in the radiopharmaceutical production process. DRLs were suggested based on a questionnaire that was used for the survey of {sup 18}F-FDG administered activity in 72 Brazilian clinics currently licensed by the National Nuclear Energy Commission (CNEN). The results reported by 41 (57%) of the {sup 18}F-FDG-PET clinics showed variations up to 100% in the administered activities among clinics for the same procedure. The calculated DRL from the third quartile was 5.54 MBq/kg or 387.7 MBq (for a 70 kg standard patient). For image analysis, two phantoms were used for obtaining the RCs, the NEMA/IEC Body Phantom, which has spherical capture areas and the modified Jaszczak, which has cylindrical capitation capture areas. Both phantoms were tested for different lesion:BG activity ratios, in the amount of 4:1 and 10:1; for different acquisition time. RCs obtained according to NEMA and IEC standards were applied to the SUVmax and SUVmed semi quantification tools. Values of SUVmed

Maillard reaction in mild-based foods: nutritional consequences.

Science.gov (United States)

Pizzoferrato, L; Manzi, P; Vivanti, V; Nicoletti, I; Corradini, C; Cogliandro, E

1998-02-01

Chemical reactions occurring during industrial treatments or storage foods can lead to the formation of epsilon-deoxyketosyl compounds, the Amadori products. Food protein value can be adversely affected by these reactions, and in particular lysine, an essential amino acid having on its side chain a free amino group, can be converted to nonbioavailable N-substituted lysine or blocked lysine. by acid hydrolysis of epsilon-deoxyketosyl compounds, furosine is formed. In this paper furosine prepared from milk-based commercial products has been evaluated by use of a recently developed HPLC method using a microbore column and phosphate buffer as the mobile phase at controlled temperature. Furosine levels have been used, together with protein, total amino acids, and lysine content, as an estimate of protein quality of a few different products such as cooked-cream dessert, yogurt mousse, white chocolate, milk chocolate, milk chocolate with a soft nougat and caramel center, milk chocolate with a whipped white center, chocolate spread, part-skim milk tablets, milk-based dietetic meals, and baby foods. The protein content of the analyzed products ranged from 34.3 gxkg(-1) (milk nougat) to 188.4 g x kg(-1) (milk tablets). The Maillard reaction caused a loss in available lysine that varied from 2.5% (cooked cream) to 36.2% (condensed milk). The contribution to the lysine average daily requirement is heavily affected by this reaction and varied from 13% (milk tablets and soft nougat) to 61% (dietetic meal). Variable results were also obtained for the other essential amino acids.

Radical Cationic Pathway for the Decay of Ionized Glyme Molecules in Liquid Solution.

Science.gov (United States)

Taletskiy, Konstantin S; Borovkov, Vsevolod I; Schegoleva, Lyudmila N; Beregovaya, Irina V; Taratayko, Andrey I; Molin, Yuriy N

2015-11-12

Chemical stability of primary radical cations (RCs) generated in irradiated matter determines substantially the radiation resistance of organic materials. Transformations of the RCs of the glyme molecules, R(-O-CH2-CH2-)nO-R (R = CH3, n = 1-4) has been studied on the nanosecond time scale by measuring the magnetic field effects in the recombination fluorescence from irradiated liquid solutions of the glymes. In all cases, the RCs observed were different from that expected for the primary ones and revealed very similar hyperfine couplings independent of the poly(ethylene oxide) chain length and of the substitution of terminal methyl groups by C2H5 or CH2CH2Cl, as has been shown with diglyme as an example. Quantum chemical analysis of possible chemical transformations for the monoglyme RC as a model system allowed us to discover the reaction pathway yielding the methyl vinyl ether RC. The pathway involves intramolecular proton transfer followed by C-O bond cleavage. Only one (-O-CH2-CH2-O-) fragment is involved in this transformation, which is nearly barrierless due to the catalytic effect of adjacent glyme molecules. The rapid formation of the methyl vinyl ether RC in the irradiated monoglyme was confirmed by the numerical simulation of the experimental curves of the time-resolved magnetic field effect. These findings suggest that the R'-O-CH═CH2(•+) formation is a typical decay pathway for the primary RCs in irradiated liquid glymes.

Aborted germinal center reactions and B cell memory by follicular T cells specific for a B cell receptor V region peptide.

Science.gov (United States)

Heiser, Ryan A; Snyder, Christopher M; St Clair, James; Wysocki, Lawrence J

2011-07-01

A fundamental problem in immunoregulation is how CD4(+) T cells react to immunogenic peptides derived from the V region of the BCR that are created by somatic mechanisms, presented in MHC II, and amplified to abundance by B cell clonal expansion during immunity. BCR neo Ags open a potentially dangerous avenue of T cell help in violation of the principle of linked Ag recognition. To analyze this issue, we developed a murine adoptive transfer model using paired donor B cells and CD4 T cells specific for a BCR-derived peptide. BCR peptide-specific T cells aborted ongoing germinal center reactions and impeded the secondary immune response. Instead, they induced the B cells to differentiate into short-lived extrafollicular plasmablasts that secreted modest quantities of Ig. These results uncover an immunoregulatory process that restricts the memory pathway to B cells that communicate with CD4 T cells via exogenous foreign Ag.

Non-equilibrium statistical mechanical approach for describing heavy ion reactions

International Nuclear Information System (INIS)

Sventek, J.S.

1979-01-01

With the availability of heavy-ion projectiles (A > 4) at low to intermediate energies (4 < E/A < 10), products showing various stages of relaxation for certain macroscopic variables (center-of-mass energy, orbital angular momentum, etc.) were produced in various reactions. The distributions for these macroscopic variables showed a correlation between the stage of relaxation reached and the net amount of mass transfer which had occurred in the reaction. There was also evidence that there was an asymmetry in the number of net transfers necessary for complete relaxation between stripping ad pickup reactions. A model for describing the time-evolution of these reactions has been formulated, the keystone of which is a master-equation approach for describing the time-dependence of the mass-asymmetry. This, coupled with deterministic equations of motion for the other macroscopic coordinates in the reaction lead to calculated distributions which provide an excellent qualitative description of these reactions, and, in some cases, quantitatively reproduce the experimental data quite well

Self-reported adverse reactions among patients initiating antiretroviral therapy in Brazil

OpenAIRE

Pádua,Cristiane A. Menezes de; César,Cibele C.; Bonolo,Palmira F.; Acurcio,Francisco A.; Guimarães,Mark Drew C.

2007-01-01

A cross-sectional analysis was carried out to describe adverse reactions to antiretroviral therapy (ART) reported by HIV-infected patients initiating treatment at two public health AIDS referral centers in Belo Horizonte, Brazil, 2001-2003 and to verify their association with selected variables. Adverse reactions were obtained through interview at the first follow-up visit (first month) after the antiretroviral prescription. Socio-demographic and behavioral variables related to ART were obtai...

C—C bond formation in the intramolecular Diels-Alder reaction of triene amides

Directory of Open Access Journals (Sweden)

Abdelilah Benallou

2018-02-01

Full Text Available The mechanism nature of the intramolecular Diels–Alder reaction has been performed; and thus, the changes of C—C bond forming/breaking along IRC are characterized in this study. Conceptual DFT analyses of the most favorable adduct fused/exo shows that the flux electronic will take place from diene to dienophile moiety. Moreover, ELF topological analysis based on the electron density predicts that C—C bond is formed by the coupling of two pseudoradical centers generated at the most significant atoms of the molecules. However, C2 vs C3, also C1 and C4 interaction comes mainly from the global electron density transfer which takes place along the reaction. Two- stage one-step is the proposed mechanism of this reaction, the first stage aims for the formation of C2—C3 σ bond while the second stage aims for C1—C4 σ bond formation. Interestingly, the observed asynchronicity of this IMDA reaction due principally to the asymmetric reorganization of electron density at the most attractive centers.

C-C bond formation in the intramolecular Diels-Alder reaction of triene amides.

Science.gov (United States)

Benallou, Abdelilah; El Alaoui El Abdallaoui, Habib; Garmes, Hocine

2018-02-01

The mechanism nature of the intramolecular Diels-Alder reaction has been performed; and thus, the changes of C-C bond forming/breaking along IRC are characterized in this study. Conceptual DFT analyses of the most favorable adduct fused/exo shows that the flux electronic will take place from diene to dienophile moiety. Moreover, ELF topological analysis based on the electron density predicts that C-C bond is formed by the coupling of two pseudoradical centers generated at the most significant atoms of the molecules. However, C2 vs C3, also C1 and C4 interaction comes mainly from the global electron density transfer which takes place along the reaction. Two- stage one-step is the proposed mechanism of this reaction, the first stage aims for the formation of C2-C3 σ bond while the second stage aims for C1-C4 σ bond formation. Interestingly, the observed asynchronicity of this IMDA reaction due principally to the asymmetric reorganization of electron density at the most attractive centers.

Closeup of STS-26 Discovery, OV-103, orbital maneuvering system (OMS) leak

Science.gov (United States)

1988-01-01

Closeup of STS-26 Discovery, Orbiter Vehicle (OV) 103, orbital maneuvering system (OMS) reaction control system (RCS) nitrogen tetroxide gas leak was captured by a Cobra borescope and displayed on a video monitor. The borescope has a miniature videocamera at the end of a flexible rubber tube and is able to be maneuvered into other inaccessible locations.

Annual Report (No. 1) of Center for Advanced Research of Energy Technology, Hokkaido University; Hokkaido Daigaku energy sentan kogaku kenkyu center nenpo dai 1 go

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-03-01

The activities of the Center cover basic researches into chemistry, physics, and materials necessary for the development of technologies relating to high-efficiency conversion of coal-centered fossil fuel resources and to the security of new energy sources. Studies under way in the field of carbonaceous resources conversion reaction involve the process of transfer of heat and substance in the coal conversion reaction, behavior of short-life intermediate products, and the structure and physical properties of coal as a molecular solid or macromolecule. Studies being conducted in the field of carbonaceous resources assessment include the search for and development of high-efficiency catalysts for coal conversion reaction systems, elucidation of physical and chemical structures of coal and coal-derived oils, energy conversion of the low-entropy type, creation of carbon-based functional materials, etc. Furthermore, research and development is under way for enhanced-efficiency conversion of high-temperature thermal energy acquired by fossil fuel combustion into electrical energy and for materials that will constitute nuclear fusion reactors and atomic reactors and will withstand combustion plasma. (NEDO)

Temperature dependence of third order ion molecule reactions. The reaction H+3 + 2H2 = H+5 + H2

International Nuclear Information System (INIS)

Hiraoka, K.; Kebarle, P.

1975-01-01

The rate constants k 1 for Reaction (1): H + 3 +2H 2 = H + 5 +H 2 were measured in the temperature range 100--300 degreeK. The temperature dependence of k 1 has the form k 1 proportionalT - /subn/, where n=2.3. Pierce and Porter have reported a much stronger negative temperature dependence with n=4.6. The difference arises from a determination of k 1 at 300 degreeK obtained by Arifov and used by Porter. The present k 1 (300 degreeK) =9times10 -30 (cm 6 molecules -2 center-dotsec -1 ). This is more than an order of magnitude larger than the Arifov value. The temperature dependence of third body dependent association reactions like (1) is examined on the basis of the energy transfer theory and the recently proposed trimolecular complex transition state theory by Meot-Ner, Solomon, Field, and Gershinowitz. The temperature dependence of the rate constant for the reverse reaction (-1) is obtained from k 1 and the previously determined temperature dependence of the equilibria (1). k/sub -//sub 1/ gives a good straight line Arrhenius plot leading to k/sub -//sub 1/ =8.7times10 -6 exp(-8.4/RT) cm 3 molecules -1 center-dotsec -1 . The activation energy is in kcal/mole. The preexponential factor is much larger than the rate constant for Langevin collisions. This is typical for pyrolysis of ions involving second order activation

Adverse reactions of Methylphenidate in children with attention deficit-hyperactivity disorder: Report from a referral center

Science.gov (United States)

Khajehpiri, Zahra; Mahmoudi-Gharaei, Javad; Faghihi, Toktam; Karimzadeh, Iman; Khalili, Hossein; Mohammadi, Mostafa

2014-01-01

Objective: The aim of the current study was to determine various aspects of methylphenidate adverse reactions in children with attention deficit-hyperactivity disorder (ADHD) in Iran. Methods: During the 6 months period, all children under methylphenidate treatment alone or along with other agents attending a university-affiliated psychology clinic were screened regarding all subjective and objective adverse drug reactions (ADRs) of methylphenidate. Causality and seriousness of detected ADRs were assessed by relevant World Health Organization definitions. The Schumock and Thornton questionnaire was used to determine preventability of ADRs. Findings: Seventy-one patients including 25 girls and 46 boys with ADHD under methylphenidate treatment were enrolled within the study period. All (100%) ADHD children under methylphenidate treatment developed at least one ADR. Anorexia (74.3%), irritability (57.1%), and insomnia (47.2%) were the most frequent methylphenidate-related adverse reactions. Except for one, all other detected ADRs were determined to be mild. In addition, no ADR was considered to be preventable and serious. Conclusion: Our data suggested that although methylphenidate related adverse reactions were common in children with ADHD, but they were mainly mild and nonserious. PMID:25535621

Near-surface layer radiation color centers in lithium fluoride nanocrystals: Luminescence and composition

Energy Technology Data Exchange (ETDEWEB)

Voitovich, A.P., E-mail: voitovich@imaph.bas-net.by; Kalinov, V.S.; Stupak, A.P.; Novikov, A.N.; Runets, L.P.

2015-01-15

Lithium fluoride nanocrystals are irradiated by gamma quanta at 77 K. The radiation color centers formed in a near-surface layer of nanocrystals are studied. Absorption, luminescence and luminescence excitation spectra of the surface defects have been measured. It has been found that the luminescence excitation spectra for aggregated surface centers consist of two or three bands with not very much different intensities. Reactions of the surface centers separately with electrons and with anion vacancies have been investigated. Numbers of anion vacancies and electrons entering into the centers composition have been established and it has been found that F{sub S1}, F{sub S1}{sup −}, F{sub S2}, F{sub S2}{sup −}, F{sub S3}{sup +} and F{sub S3} types of the surface centers are formed. The degree of luminescence polarization has been defined and it has been determined that the polarization degree for F{sub S2}{sup +} centers changes sign under transition from one excitation band to another. It has been shown that during irradiation at 77 K radiation-induced defects are formed more efficiently on the surface than in the bulk. - Highlights: • Radiative color centers were fabricated in lithium fluoride nanocrystals. • The unique absorption and luminescence characteristics are inherent in the centers. • The reactions of these centers with electrons and anion vacancies were studied. • The degree of luminescence polarization was defined. • Numbers of anion vacancies and electrons forming the centers were established.

Reactions of Hydroxyalkyl Radicals with Cysteinyl Peptides in a NanoESI Plume

Science.gov (United States)

Stinson, Craig A.; Xia, Yu

2014-07-01

In biological systems, carbon-centered small molecule radicals are primarily formed via external radiation or internal radical reactions. These radical species can react with a variety of biomolecules, most notably nucleic acids, the consequence of which has possible links to gene mutation and cancer. Sulfur-containing peptides and proteins are reactive toward a variety of radical species and many of them behave as radical scavengers. In this study, the reactions between alkyl alcohol carbon-centered radicals (e.g., •CH2OH for methanol) and cysteinyl peptides within a nanoelectrospray ionization (nanoESI) plume were explored. The reaction system involved ultraviolet (UV) irradiation of a nanoESI plume using a low pressure mercury lamp consisting of 185 and 254 nm emission bands. The alkyl alcohol was added as solvent into the nanoESI solution and served as the precursor of hydroxyalkyl radicals upon UV irradiation. The hydroxyalkyl radicals subsequently reacted with cysteinyl peptides either containing a disulfide linkage or free thiol, which led to the formation of peptide- S-hydroxyalkyl product. This radical reaction coupled with subsequent MS/MS was shown to have analytical potential by cleaving intrachain disulfide linked peptides prior to CID to enhance sequence information. Tandem mass spectrometry via collision-induced dissociation (CID), stable isotope labeling, and accurate mass measurement were employed to verify the identities of the reaction products.

Comparing of the Reaction Time in Substance-Dependent and Non-Dependent Individuals

Directory of Open Access Journals (Sweden)

Mohammad Narimani

2012-11-01

Full Text Available Aim: The aim of this study was to compare the simple, selective, and discrimination reaction time in substance-dependent and non-dependent individuals. Method: In this causal-comparative study, the population included of 425 males (opium and crystal dependents who were referred to addiction rehabilitation centers in Tabriz. By random sampling, 16 opium dependents, 16 crystal dependents, and 16 non-dependent individuals with no history of dependency as the compare group were selected. All groups peered in age, and marital status. For gathering data, “Addicts Admit Questionnaire” and laboratory device known as the "Reaction Time Assay" have been used. Results: The results of this study showed that there are significant differences among all groups in simple reaction time, choice reaction time and reaction time to auditory stimuli, but no significant difference in discrimination reaction time and reaction time to visual stimulus observed. Conclusion: The reaction time of substance-dependent groups is slower than non-dependent groups.

Insights into the mechanisms on chemical reactions: reaction paths for chemical reactions

International Nuclear Information System (INIS)

Dunning, T.H. Jr.; Rosen, E.; Eades, R.A.

1987-01-01

We report reaction paths for two prototypical chemical reactions: Li + HF, an electron transfer reaction, and OH + H 2 , an abstraction reaction. In the first reaction we consider the connection between the energetic terms in the reaction path Hamiltonian and the electronic changes which occur upon reaction. In the second reaction we consider the treatment of vibrational effects in chemical reactions in the reaction path formalism. 30 refs., 9 figs

Reaction rates for neutrino processes

International Nuclear Information System (INIS)

Shalitin, D.

1978-01-01

Some integrals involved in neutrino processes are evaluated by transformation to a special system of reference - usually to the center of mass system (CM). Rather simple analytic expressions are obtained for reaction rates and, though less simple, for moments. An interesting result thus obtained is for an isotropic interaction (in CM) of a neutrino with a monoenergetic isotropic gas of extreme relativistic electrons: it is found that the probability of the scattered neutrino to have energy in a certain range is independent of this energy. (Auth.)

Validation of a 15-item care-related regret coping scale for health-care professionals (RCS-HCP).

Science.gov (United States)

Courvoisier, Delphine Sophie; Cullati, Stephane; Ouchi, Rieko; Schmidt, Ralph Eric; Haller, Guy; Chopard, Pierre; Agoritsas, Thomas; Perneger, Thomas V

2014-01-01

Coping with difficult care-related situations is a common challenge for health-care professionals. How these professionals deal with the regrets they may experience following one of the many decisions and interventions they must make every day can have an impact on their own health and quality of life, and also on their patient care practices. To identify professionals most at need for extra support, development and validation of a tool measuring coping style are needed. We performed a survey of physicians and nurses of a French-speaking University hospital; 469 health-care professionals responded to the survey, and 175 responded to the same survey one-month later. Regret was assessed with the regret coping scale developed for this study, self-report questions on the frequency of regretted situations and the intensity of regret. Construct validity was assessed using measures of health-care professionals' quality of life (including job and life satisfaction, and self-reported health) as well as sleep problems and depression. Based on factor analysis and item response analysis, the initial 31-item scale was shortened to 15 items, which measured three types of strategies: problem-focused strategies (i.e., trying to find solutions, talking to colleagues) and two types of emotion-focused strategies, A (i.e., self-blame, rumination) and B (e.g., acceptance, emotional distance). All subscales showed high internal consistency (α >0.85). Overall, as expected, problem-focused and emotion-focused B strategies correlated with higher quality of life, fewer sleep problems and less depression, and emotion-focused A strategies showed the opposite pattern. The regret coping scale (RCS-HCP) is a valid and reliable measure of coping abilities of hospital-based health-care professionals.

A phenomenological study of the π- p → π0 n charge exchange reaction at high energy

International Nuclear Information System (INIS)

Michaud, Y.

1995-01-01

The aim of the study was to examine the behaviour of the proton-proton elastic scattering, for mass center energies around 10 GeV, and more especially to study the charge exchange reaction π - p → π 0 n for mass center energies between 3 and 20 GeV. A formalism based on the Glauber model has been used, and a Regge trajectory exchange term was introduced in the model in order to enable the description of the lower energy domain (inferior to 10 GeV) that is characterized by a large contribution of meson exchanges at the scattering amplitude. The Glauber model is then applied to the charge exchange reaction and the differential cross section is analyzed for a center mass energy comprised between 3 and 20 GeV, together with the polarization at 40 GeV/c. The approach is then validated through the study of the π - p → η n reaction. The size of the kernel of proton and pion components implied in the π - p → π 0 n reaction, is also investigated. 90 refs., 48 figs., 4 tabs., 5 appends

Direct single-molecule dynamic detection of chemical reactions.

Science.gov (United States)

Guan, Jianxin; Jia, Chuancheng; Li, Yanwei; Liu, Zitong; Wang, Jinying; Yang, Zhongyue; Gu, Chunhui; Su, Dingkai; Houk, Kendall N; Zhang, Deqing; Guo, Xuefeng

2018-02-01

Single-molecule detection can reveal time trajectories and reaction pathways of individual intermediates/transition states in chemical reactions and biological processes, which is of fundamental importance to elucidate their intrinsic mechanisms. We present a reliable, label-free single-molecule approach that allows us to directly explore the dynamic process of basic chemical reactions at the single-event level by using stable graphene-molecule single-molecule junctions. These junctions are constructed by covalently connecting a single molecule with a 9-fluorenone center to nanogapped graphene electrodes. For the first time, real-time single-molecule electrical measurements unambiguously show reproducible large-amplitude two-level fluctuations that are highly dependent on solvent environments in a nucleophilic addition reaction of hydroxylamine to a carbonyl group. Both theoretical simulations and ensemble experiments prove that this observation originates from the reversible transition between the reactant and a new intermediate state within a time scale of a few microseconds. These investigations open up a new route that is able to be immediately applied to probe fast single-molecule physics or biophysics with high time resolution, making an important contribution to broad fields beyond reaction chemistry.

NASA Glenn Research Center Experience with "LENR Phenomenon"

Science.gov (United States)

Wrbanek, Susan Y.; Fralick, Gustave C.; Wrbanek, John D.; Niedra, Janis M.

2012-01-01

Since 1989 NASA Glenn Research Center (GRC) has performed some small-scale limited experiments that show evidence of effects claimed by some to be evidence of Low Energy Nuclear Reactions (LENR). The research at GRC has involved observations and work on measurement techniques for observing the temperature effects in reactions of isotopes of hydrogen with palladium hydrides. The various experiments performed involved loading Pd with gaseous H2 and D2, and exposing Pd thin films to multi-bubble sonoluminescence in regular and deuterated water. An overview of these experiments and their results will be presented.

NASA Glenn Research Center Experience with LENR Phenomenon

Science.gov (United States)

Wrbanek, Susan Y.; Fralick, Gustave C.; Wrbanek, John D.; Niedra, Janis M.

2012-01-01

Since 1989 NASA Glenn Research Center (GRC) has performed some small-scale limited experiments that show evidence of effects claimed by some to be evidence of Low Energy Nuclear Reactions (LENR). The research at GRC has involved observations and work on measurement techniques for observing the temperature effects in reactions of isotopes of hydrogen with palladium hydrides. The various experiments performed involved loading Pd with gaseous H2 and D2, and exposing Pd thin films to multi-bubble sonoluminescence in regular and deuterated water. An overview of these experiments and their results will be presented.

A phenomenological study of the {pi}{sup -} p {yields} {pi}{sup 0} n charge exchange reaction at high energy; Etude phenomenologique de la reaction d`echange de charge {pi}{sup -} p {yields} {pi}{sup 0} n a haute energie

Energy Technology Data Exchange (ETDEWEB)

Michaud, Y

1995-09-21

The aim of the study was to examine the behaviour of the proton-proton elastic scattering, for mass center energies around 10 GeV, and more especially to study the charge exchange reaction {pi}{sup -} p {yields} {pi}{sup 0} n for mass center energies between 3 and 20 GeV. A formalism based on the Glauber model has been used, and a Regge trajectory exchange term was introduced in the model in order to enable the description of the lower energy domain (inferior to 10 GeV) that is characterized by a large contribution of meson exchanges at the scattering amplitude. The Glauber model is then applied to the charge exchange reaction and the differential cross section is analyzed for a center mass energy comprised between 3 and 20 GeV, together with the polarization at 40 GeV/c. The approach is then validated through the study of the {pi}{sup -} p {yields} {eta} n reaction. The size of the kernel of proton and pion components implied in the {pi}{sup -} p {yields} {pi}{sup 0} n reaction, is also investigated. 90 refs., 48 figs., 4 tabs., 5 appends.

The comprehension of Italian relative clauses in poor readers and in children with Specific Language Impairment

Directory of Open Access Journals (Sweden)

Fabrizio Arosio

2017-02-01

Full Text Available Children with Specific Language Impairment (SLI and children with Developmental Dyslexia (DD have problems comprehending relative clauses (RCs and find object RCs more difficult than subject RCs, as do typically developing children. Few studies have compared these groups directly, leaving it unclear whether the problems observed in children with DD are similar to those described in SLI. Work with typically developing children has shown that the comprehension of passive RCs is less challenging than that of object RCs. It is argued that this asymmetry depends on intervention effects as modelized in a Relativized Minimality framework. Since movement is challenging for children with SLI and those with DD, examining and comparing their comprehension of object RCs and passive RCs can broaden our understanding of their language deficits. In fact, both structures involve movement, but the moved element and the movement configuration are different. In our study we investigated the comprehension of subject RCs, object RCs and passive RCs in 12 Italian monolingual children with SLI (mean age: 7;6, 13 Italian monolingual children with DD (mean age: 10;7 and 50 typically developing controls matched for age, grammar and vocabulary. Results from a picture selection task show that: (i subject RCs are unproblematic for all children; (ii object RCs are challenging for children with SLI, children with DD and younger typically developing controls; (iii passive RCs are better understood than object RCs in all groups, but still problematic for children with SLI and younger typically developing controls. Our data show that intervention effects are found in children with SLI and children with DD and that those with SLI have a deficit in transferring thematic roles to moved elements. Our results point out that some of the children with DD have a mild grammatical deficit that was undetected or escaped standardized tests.

Biophysical network modeling of the dLGN circuit: Effects of cortical feedback on spatial response properties of relay cells.

Directory of Open Access Journals (Sweden)

Pablo Martínez-Cañada

2018-01-01

Full Text Available Despite half-a-century of research since the seminal work of Hubel and Wiesel, the role of the dorsal lateral geniculate nucleus (dLGN in shaping the visual signals is not properly understood. Placed on route from retina to primary visual cortex in the early visual pathway, a striking feature of the dLGN circuit is that both the relay cells (RCs and interneurons (INs not only receive feedforward input from retinal ganglion cells, but also a prominent feedback from cells in layer 6 of visual cortex. This feedback has been proposed to affect synchronicity and other temporal properties of the RC firing. It has also been seen to affect spatial properties such as the center-surround antagonism of thalamic receptive fields, i.e., the suppression of the response to very large stimuli compared to smaller, more optimal stimuli. Here we explore the spatial effects of cortical feedback on the RC response by means of a a comprehensive network model with biophysically detailed, single-compartment and multicompartment neuron models of RCs, INs and a population of orientation-selective layer 6 simple cells, consisting of pyramidal cells (PY. We have considered two different arrangements of synaptic feedback from the ON and OFF zones in the visual cortex to the dLGN: phase-reversed ('push-pull' and phase-matched ('push-push', as well as different spatial extents of the corticothalamic projection pattern. Our simulation results support that a phase-reversed arrangement provides a more effective way for cortical feedback to provide the increased center-surround antagonism seen in experiments both for flashing spots and, even more prominently, for patch gratings. This implies that ON-center RCs receive direct excitation from OFF-dominated cortical cells and indirect inhibitory feedback from ON-dominated cortical cells. The increased center-surround antagonism in the model is accompanied by spatial focusing, i.e., the maximum RC response occurs for smaller stimuli

Biophysical network modeling of the dLGN circuit: Effects of cortical feedback on spatial response properties of relay cells

Science.gov (United States)

Martínez-Cañada, Pablo; Halnes, Geir; Fyhn, Marianne

2018-01-01

Despite half-a-century of research since the seminal work of Hubel and Wiesel, the role of the dorsal lateral geniculate nucleus (dLGN) in shaping the visual signals is not properly understood. Placed on route from retina to primary visual cortex in the early visual pathway, a striking feature of the dLGN circuit is that both the relay cells (RCs) and interneurons (INs) not only receive feedforward input from retinal ganglion cells, but also a prominent feedback from cells in layer 6 of visual cortex. This feedback has been proposed to affect synchronicity and other temporal properties of the RC firing. It has also been seen to affect spatial properties such as the center-surround antagonism of thalamic receptive fields, i.e., the suppression of the response to very large stimuli compared to smaller, more optimal stimuli. Here we explore the spatial effects of cortical feedback on the RC response by means of a a comprehensive network model with biophysically detailed, single-compartment and multicompartment neuron models of RCs, INs and a population of orientation-selective layer 6 simple cells, consisting of pyramidal cells (PY). We have considered two different arrangements of synaptic feedback from the ON and OFF zones in the visual cortex to the dLGN: phase-reversed (‘push-pull’) and phase-matched (‘push-push’), as well as different spatial extents of the corticothalamic projection pattern. Our simulation results support that a phase-reversed arrangement provides a more effective way for cortical feedback to provide the increased center-surround antagonism seen in experiments both for flashing spots and, even more prominently, for patch gratings. This implies that ON-center RCs receive direct excitation from OFF-dominated cortical cells and indirect inhibitory feedback from ON-dominated cortical cells. The increased center-surround antagonism in the model is accompanied by spatial focusing, i.e., the maximum RC response occurs for smaller stimuli when

[Development of boomerang-type intramolecular cascade reactions and application to natural product synthesis].

Science.gov (United States)

Takasu, K

2001-12-01

Intramolecular cascade reaction has received much attention as a powerful methodology to construct a polycyclic framework in organic synthesis. We have been developing "boomerang-type cascade reaction" to construct a variety of polycyclic skeletons efficiently. In the above reactions, a nucleophilic function of substrates changes the character into an electrophile after the initial reaction, and the electrophilic group acts as a nucleophile in the second reaction. That is, the reaction center stepwise moves from one functional group back to the same one via other functional groups. The stream of the electron concerning the cascade reaction is like a locus of boomerang. We show here three different boomerang-type reactions via ionic species or free radicals. 1) Diastereoselective Michael-aldol reaction based on the chiral auxiliary method and enantioselective Michael-aldol reaction by the use of external chiral sources. 2) Short and efficient total syntheses of longifolane sesquiterpenes utilizing intramolecular double Michael addition as a key step. 3) Development of boomerang-type radical cascade reaction of halopolyenes to construct terpenoid skeletons and its regioselectivity.

Structure of the dimeric PufX-containing core complex of Rhodobacter blasticus by in situ atomic force microscopy.

Science.gov (United States)

Scheuring, Simon; Busselez, Johan; Lévy, Daniel

2005-01-14

We have studied photosynthetic membranes of wild type Rhodobacter blasticus, a closely related strain to the well studied Rhodobacter sphaeroides, using atomic force microscopy. High-resolution atomic force microscopy topographs of both cytoplasmic and periplasmic surfaces of LH2 and RC-LH1-PufX (RC, reaction center) complexes were acquired in situ. The LH2 is a nonameric ring inserted into the membrane with the 9-fold axis perpendicular to the plane. The core complex is an S-shaped dimer composed of two RCs, each encircled by 13 LH1 alpha/beta-heterodimers, and two PufXs. The LH1 assembly is an open ellipse with a topography-free gap of approximately 25 A. The two PufXs, one of each core, are located at the dimer center. Based on our data, we propose a model of the core complex, which provides explanation for the PufX-induced dimerization of the Rhodobacter core complex. The QB site is located facing a approximately 25-A wide gap within LH1, explaining the PufX-favored quinone passage in and out of the core complex.

X-ray and EPR study of reactions between B4C and TiO2

International Nuclear Information System (INIS)

Kakazey, M.; Vlasova, M.; Gonzalez-Rodriguez, J.G.; Dominguez-Patino, M.; Leder, R.

2006-01-01

X-ray diffraction and electron paramagnetic resonance (EPR) methods have been used to study the reaction process in a system of 95 wt.% of B 4 C + 5 wt.% TiO 2 . The addition of TiO 2 to B 4 C was effective in accelerating the removal of carbon inclusions. Two types of reactions between B 4 C and TiO 2 , starting at temperatures ∼1173 K, took place: (a) gas-transport exchange and (b) diffusion of Ti atoms into the B 4 C lattice. These reactions modify the number and type of donor centers in the B 4 C. The dependence of EPR line width on the number of donor centers in B 4 C (from conditions of sample treatment) is a useful method for investigating the formation of powders and ceramics based on B 4 C

Nuclear information services at the National Nuclear Data Center

International Nuclear Information System (INIS)

Burrows, T.W.; Tuli, J.K.

1997-01-01

The National Nuclear Data Center (NNDC) at the Brookhaven National Laboratory has maintained and disseminated data from several numeric and bibliographic data bases for many years. These data bases now cover most of low- and medium-energy nuclear physics and are produced by the NNDC and other groups belonging to various international and national networks. The numeric and bibliographic nuclear data bases maintained by the National Nuclear Data Center and access to these data bases is described. The U.S. Nuclear Data and Reaction Data Networks is also briefly described. (author)

Annual report of Tandem Accelerator Center, University of Tsukuba, for fiscal 1975

International Nuclear Information System (INIS)

1976-01-01

Tandem Accelerator Center (TAC) is a research center of the University of Tsukuba established mainly for interdisciplinary research. Its principal apparatus is a 12 UD Pelletron tandem accelerator of which assembling was completed in fiscal 1975. Activities of the TAC for the period of April 1975 to March 1976 are reported: accelerator and beam transport system, general equipments, equipment development, and heavy-ion reactions. (Mori, K.)

Ab initio molecular dynamics simulations for the role of hydrogen in catalytic reactions of furfural on Pd(111)

Science.gov (United States)

Xue, Wenhua; Dang, Hongli; Liu, Yingdi; Jentoft, Friederike; Resasco, Daniel; Wang, Sanwu

2014-03-01

In the study of catalytic reactions of biomass, furfural conversion over metal catalysts with the presence of hydrogen has attracted wide attention. We report ab initio molecular dynamics simulations for furfural and hydrogen on the Pd(111) surface at finite temperatures. The simulations demonstrate that the presence of hydrogen is important in promoting furfural conversion. In particular, hydrogen molecules dissociate rapidly on the Pd(111) surface. As a result of such dissociation, atomic hydrogen participates in the reactions with furfural. The simulations also provide detailed information about the possible reactions of hydrogen with furfural. Supported by DOE (DE-SC0004600). This research used the supercomputer resources of the XSEDE, the NERSC Center, and the Tandy Supercomputing Center.

Laser Spot Detection Based on Reaction Diffusion.

Science.gov (United States)

Vázquez-Otero, Alejandro; Khikhlukha, Danila; Solano-Altamirano, J M; Dormido, Raquel; Duro, Natividad

2016-03-01

Center-location of a laser spot is a problem of interest when the laser is used for processing and performing measurements. Measurement quality depends on correctly determining the location of the laser spot. Hence, improving and proposing algorithms for the correct location of the spots are fundamental issues in laser-based measurements. In this paper we introduce a Reaction Diffusion (RD) system as the main computational framework for robustly finding laser spot centers. The method presented is compared with a conventional approach for locating laser spots, and the experimental results indicate that RD-based computation generates reliable and precise solutions. These results confirm the flexibility of the new computational paradigm based on RD systems for addressing problems that can be reduced to a set of geometric operations.

A theoretical study of the H-abstraction reactions from HOI by moist air radiolytic products (H, OH, and O (3P)) and iodine atoms (2P(3/2)).

Science.gov (United States)

Hammaecher, Catherine; Canneaux, Sébastien; Louis, Florent; Cantrel, Laurent

2011-06-23

The rate constants of the reactions of HOI molecules with H, OH, O ((3)P), and I ((2)P(3/2)) atoms have been estimated over the temperature range 300-2500 K using four different levels of theory. Geometry optimizations and vibrational frequency calculations are performed using MP2 methods combined with two basis sets (cc-pVTZ and 6-311G(d,p)). Single-point energy calculations are performed with the highly correlated ab initio coupled cluster method in the space of single, double, and triple (pertubatively) electron excitations CCSD(T) using the cc-pVTZ, cc-pVQZ, 6-311+G(3df,2p), and 6-311++G(3df,3pd) basis sets. Reaction enthalpies at 0 K were calculated at the CCSD(T)/cc-pVnZ//MP2/cc-pVTZ (n = T and Q), CCSD(T)/6-311+G(3df,2p)//MP2/6-311G(d,p), and CCSD(T)/6-311++G(3df,3pd)//MP2/6-311G(d,p) levels of theory and compared to the experimental values taken from the literature. Canonical transition-state theory with an Eckart tunneling correction is used to predict the rate constants as a function of temperature. The computational procedure has been used to predict rate constants for H-abstraction elementary reactions because there are actually no literature data to which the calculated rate constants can be directly compared. The final objective is to implement kinetics of gaseous reactions in the ASTEC (accident source term evaluation code) program to improve speciation of fission products, which can be transported along the reactor coolant system (RCS) of a pressurized water reactor (PWR) in the case of a severe accident.

Changes of Photosynthetic Behaviors in Kappaphycus alvarezii Infected by Epiphyte

Directory of Open Access Journals (Sweden)

Tong Pang

2011-01-01

Full Text Available Epiphytic filamentous algae (EFA were noted as a serious problem to reduce the production and quality of K. alvarezii. The morphological studies revealed that the main epiphyte on K. alvarezii was Neosiphonia savatieri in China. Though the harmful effects of EFA on the production of K. alvarezii have been reported, the detailed mechanism of the N. savatieri in limiting the production of K. alvarezii has not been studied yet. The present paper studied the effects of N. savatieri infection on photosynthetic behaviors in K. alvarezii by detecting chlorophyll fluorescence transient in vivo. The results revealed that damage of oxygen-evolving complex (OEC, decrease of active reaction centers (RCs, and the plastoquinone (PQ pool as well as significant reduction in the performance indexes (PI of PSII were caused by the infection of N. savatieri. The influence of N. savatieri on photosynthetic activity of K. alvarezii should be one of the important reasons to reduce the production of K. alvarezii infected by N. savatieri.

Changes of Photosynthetic Behaviors in Kappaphycus alvarezii Infected by Epiphyte.

Science.gov (United States)

Pang, Tong; Liu, Jianguo; Liu, Qian; Lin, Wei

2011-01-01

Epiphytic filamentous algae (EFA) were noted as a serious problem to reduce the production and quality of K. alvarezii. The morphological studies revealed that the main epiphyte on K. alvarezii was Neosiphonia savatieri in China. Though the harmful effects of EFA on the production of K. alvarezii have been reported, the detailed mechanism of the N. savatieri in limiting the production of K. alvarezii has not been studied yet. The present paper studied the effects of N. savatieri infection on photosynthetic behaviors in K. alvarezii by detecting chlorophyll fluorescence transient in vivo. The results revealed that damage of oxygen-evolving complex (OEC), decrease of active reaction centers (RCs), and the plastoquinone (PQ) pool as well as significant reduction in the performance indexes (PI) of PSII were caused by the infection of N. savatieri. The influence of N. savatieri on photosynthetic activity of K. alvarezii should be one of the important reasons to reduce the production of K. alvarezii infected by N. savatieri.

Chemical research on red pigments after adverse reactions to tattoo.

Science.gov (United States)

Tammaro, A; Toniolo, C; Giulianelli, V; Serafini, M; Persechino, S

2016-03-01

Currently, the incidence of tattooing is on the rise compared to the past, especially among adolescents, and it leads to the urgency of monitoring the security status of tattooing centers, as well as to inform people about the risks of tattoo practice. In our clinical experience, 20% of tattooed patients presented adverse reactions, like allergic contact dermatitis, psoriasis with Koebner's phenomena and granulomatous reactions, with the latter most prevalent and most often related to red pigment. Adverse reactions to tattoo pigments, especially the red one, are well known and described in literature. Great attention has to be focused on the pigments used, especially for the presence of new substances, often not well known. For this reason, we decided to perform a study on 12 samples of red tattoo ink, obtained by patients affected by different cutaneous reactions in the site of tattoo, to analyze their chemical composition.

Quinine-Promoted, Enantioselective Boron-Tethered Diels-Alder Reaction by Anomeric Control of Transition State Conformation.

Science.gov (United States)

Scholl, Katie; Dillashaw, John; Timpy, Evan; Lam, Yu-Hong; DeRatt, Lindsey; Benton, Tyler R; Powell, Jacqueline P; Houk, Kendall N; Morgan, Jeremy B

2018-05-01

Diels-Alder reactions of tethered vinyl-metal species offer the opportunity to fashion highly functionalized diol intermediates for synthesis. We have developed the first enantioselective boron-tethered Diels-Alder reaction using quinine as a chiral promoter. Quinine recovery, enantioselectivity enhancement, and manipulation of the cyclohexene core are also investigated. DFT modeling calculations confirm the role of quinine as a bidentate ligand enhancing reaction rates. The enantioselectivity of the cycloaddition is proposed to originate from a boron-centered anomeric effect.

Warship Radar Signatures (Ship Survivability Part III-A)

NARCIS (Netherlands)

Galle, L.F.; Heemskerk, H.J.M.; Ewijk, L.J. van

2000-01-01

Radar Cross Section (RCS) management is of paramount importance for a warships's survivability. In this first part of the paper (Part III-A), the operational benefits of low RCS will be explained. Basic RCS theory, measurement and simulation techniques will be addressed. The RCS of representative

Reduction reactions of water soluble cyano-cobalt(III)-porphyrins: Metal versus ligand centered processes

International Nuclear Information System (INIS)

Mosseri, S.; Neta, P.; Harriman, A.; Hambright, P.

1990-01-01

Reduction reactions of dicyano-cobalt(III)-porphyrins [potential in vivo cyanide scavenger drugs] were studied by radiolytic and electrochemical methods using the water soluble tetrakis(4-sulfonatophenyl)porphyrin (TPPS) and tetrakis(N-methyl-4-pyridyl)porphyrin (TMPyP). For [(CN)2CoIIITPPS]-, reduction occurs stepwise to the CoII, CoI, and finally to the phlorin anion. This behavior is similar to that of the cobalt porphyrins in the absence of cyanide, except that the cyanide ligand shifts the reduction potentials to much more negative values. On the other hand, under radiolytic conditions, [(CN)2CoIIITMPyP]- is reduced on the porphyrin macrocycle by one electron to give the CoIII pi-radical anion, which disproportionates into the initial complex and the two-electron ring reduced CoIII phlorin. The radical anion is also formed by intramolecular electron transfer subsequent to the reaction of CoIITMPyP and cyanide. The results are compared with the chemistry of Vitamin B-12

Probing the Energy Transfer Dynamics of Photosynthetic Reaction Center Complexes Through Hole-Burning and Single-Complex Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Riley, Kerry Joseph [Iowa State Univ., Ames, IA (United States)

2007-01-01

Photosynthesis is the process by which light energy is used to drive reactions that generate sugars to supply energy for cellular processes. It is one of the most important fundamental biological reactions and occurs in both prokaryotic (e.g. bacteria) and eukaryotic (e.g. plants and algae) organisms. Photosynthesis is also remarkably intricate, requiring the coordination of many different steps and reactions in order to successfully transform absorbed solar energy into a biochemical usable form of energy. However, the net reaction for all photosynthetic organisms can be reduced to the following, deceptively general, equation developed by Van Niel[1] H₂ - D + A_implies^hv A - H₂ + D where H₂-D is the electron donor, e.g. H₂O, H₂S. A is the electron acceptor, e.g. CO₂, and A-H₂ is the synthesized sugar. Amazingly, this simple net equation is responsible for creating the oxidizing atmosphere of Earth and the recycling of CO₂, both of which are necessary for the sustainment of the global ecosystem.

BNL325 - Nuclear reaction data display program

International Nuclear Information System (INIS)

Dunford, C.L.

1994-01-01

A computer code for the graphical display of nuclear reaction data is described. The code, which works on a computer with VMS operating system, can overlay experimental data from an EXFOR/CSISRS table-computation format with evaluated data from ENDF formatted data libraries. Originally, this code has been used at the U.S. National Nuclear Data Center to produce the well-known neutron cross-section atlas published as report BNL-325. (author). 3 tabs

BNL325 - Nuclear reaction data display program

Energy Technology Data Exchange (ETDEWEB)

Dunford, C L

1994-11-27

A computer code for the graphical display of nuclear reaction data is described. The code, which works on a computer with VMS operating system, can overlay experimental data from an EXFOR/CSISRS table-computation format with evaluated data from ENDF formatted data libraries. Originally, this code has been used at the U.S. National Nuclear Data Center to produce the well-known neutron cross-section atlas published as report BNL-325. (author). 3 tabs.

Enantioselective Decarboxylative Alkylation Reactions: Catalyst Development, Substrate Scope, and Mechanistic Studies

Science.gov (United States)

Behenna, Douglas C.; Mohr, Justin T.; Sherden, Nathaniel H.; Marinescu, Smaranda C.; Harned, Andrew M.; Tani, Kousuke; Seto, Masaki; Ma, Sandy; Novák, Zoltán; Krout, Michael R.; McFadden, Ryan M.; Roizen, Jennifer L.; Enquist, John A.; White, David E.; Levine, Samantha R.; Petrova, Krastina V.; Iwashita, Akihiko; Virgil, Scott C.; Stoltz, Brian M.

2012-01-01

α-Quaternary ketones are accessed through novel enantioselective alkylations of allyl and propargyl electrophiles by unstabilized prochiral enolate nucleophiles in the presence of palladium complexes with various phosphinooxazoline (PHOX) ligands. Excellent yields and high enantiomeric excesses are obtained from three classes of enolate precursors: enol carbonates, enol silanes, and racemic β-ketoesters. Each of these substrate classes functions with nearly identical efficiency in terms of yield and enantioselectivity. Catalyst discovery and development, the optimization of reaction conditions, the exploration of reaction scope, and applications in target-directed synthesis are reported. Experimental observations suggest that these alkylation reactions occur through an unusual inner-sphere mechanism involving binding of the prochiral enolate nucleophile directly to the palladium center. PMID:22083969

Enantioselective Decarboxylative Alkylation Reactions: Catalyst Development, Substrate Scope, and Mechanistic Studies

KAUST Repository

Behenna, Douglas C.; Mohr, Justin T.; Sherden, Nathaniel H.; Marinescu, Smaranda C.; Harned, Andrew M.; Tani, Kousuke; Seto, Masaki; Ma, Sandy; Nová k, Zoltá n; Krout, Michael R.; McFadden, Ryan M.; Roizen, Jennifer L.; Enquist, John A.; White, David E.; Levine, Samantha R.; Petrova, Krastina V.; Iwashita, Akihiko; Virgil, Scott C.; Stoltz, Brian M.

2011-01-01

α-Quaternary ketones are accessed through novel enantioselective alkylations of allyl and propargyl electrophiles by unstabilized prochiral enolate nucleophiles in the presence of palladium complexes with various phosphinooxazoline (PHOX) ligands. Excellent yields and high enantiomeric excesses are obtained from three classes of enolate precursor: enol carbonates, enol silanes, and racemic β-ketoesters. Each of these substrate classes functions with nearly identical efficiency in terms of yield and enantioselectivity. Catalyst discovery and development, the optimization of reaction conditions, the exploration of reaction scope, and applications in target-directed synthesis are reported. Experimental observations suggest that these alkylation reactions occur through an unusual inner-sphere mechanism involving binding of the prochiral enolate nucleophile directly to the palladium center.

Enantioselective Decarboxylative Alkylation Reactions: Catalyst Development, Substrate Scope, and Mechanistic Studies

KAUST Repository

Behenna, Douglas C.

2011-11-14

α-Quaternary ketones are accessed through novel enantioselective alkylations of allyl and propargyl electrophiles by unstabilized prochiral enolate nucleophiles in the presence of palladium complexes with various phosphinooxazoline (PHOX) ligands. Excellent yields and high enantiomeric excesses are obtained from three classes of enolate precursor: enol carbonates, enol silanes, and racemic β-ketoesters. Each of these substrate classes functions with nearly identical efficiency in terms of yield and enantioselectivity. Catalyst discovery and development, the optimization of reaction conditions, the exploration of reaction scope, and applications in target-directed synthesis are reported. Experimental observations suggest that these alkylation reactions occur through an unusual inner-sphere mechanism involving binding of the prochiral enolate nucleophile directly to the palladium center.

Characterization of hypersensitivity reactions reported among Andrographis paniculata users in Thailand using Health Product Vigilance Center (HPVC) database.

Science.gov (United States)

Suwankesawong, Wimon; Saokaew, Surasak; Permsuwan, Unchalee; Chaiyakunapruk, Nathorn

2014-12-24

Andrographis paniculata (andrographis) is one of the herbal products that are widely used for various indications. Hypersensitivity reactions have been reported among subjects receiving Andrographis paniculata in Thailand. Understanding of characteristics of patients, adverse events, and clinical outcomes is essential for ensuring population safety.This study aimed to describe the characteristics of hypersensitivity reactions reported in patients receiving andrographis containing products in Thailand using national pharmacovigilance database. Thai Vigibase data from February 2001 to December 2012 involving andrographis products were used. This database includes the reports submitted through the spontaneous reporting system and intensive monitoring programmes. The database contained patient characteristic, adverse events associated with andrographis products, and details on seriousness, causality, and clinical outcomes. Case reports were included for final analysis if they met the inclusion criteria; 1) reports with andrographis being the only suspected cause, 2) reports with terms consistent with the constellation of hypersensitivity reactions, and 3) reports with terms considered critical terms according to WHO criteria. Descriptive statistics were used. A total of 248 case reports of andrographis-associated adverse events were identified. Only 106 case reports specified andrographis herbal product as the only suspected drug and reported at least one term consistent with constellation of hypersensitivity reactions. Most case reports (89%) came from spontaneous reporting system with no previously documented history of drug allergy (88%). Of these, 18 case reports were classified as serious with 16 cases requiring hospitalization. For final assessment, the case reports with terms consistent with constellation of hypersensitivity reactions and critical terms were included. Thirteen case reports met such criteria including anaphylactic shock (n = 5), anaphylactic

Physiological and photosynthetic response of quinoa to drought stress

Directory of Open Access Journals (Sweden)

Rachid Fghire

2015-06-01

Full Text Available Water shortage is a critical problem touching plant growth and yield in semi-arid areas, for instance the Mediterranean región. For this reason was studied the physiological basis of drought tolerance of a new, drought tolerant crop quinoa (Chenopodium quinoa Willd. tested in Morocco in two successive seasons, subject to four irrigation treatments (100, 50, and 33%ETc, and rainfed. The chlorophyll a fluorescence transients were analyzed by the JIP-test to transíate stress-induced damage in these transients to changes in biophysical parameter's allowing quantification of the energy flow through the photosynthetic apparatus. Drought stress induced a significant decrease in the maximum quantum yield of primary photochemistry (Φpo = Fv/Fm, and the quantum yield of electron transport (Φeo. The amount of active Photosystem II (PSII reaction centers (RC per excited cross section (RC/CS also decreased when exposed to the highest drought stress. The effective antenna size of active RCs (ABS/RC increased and the effective dissipation per active reaction centers (DIo/RC increased by increasing drought stress during the growth season in comparison to the control. However the performance index (PI, was a very sensitive indicator of the physiological status of plants. Leaf area index, leaf water potential and stomatal conductance decreased as the drought increased. These results indicate that, in quinoa leaf, JIP-test can be used as a sensitive method for measuring drought stress effects.

A workshop report on nuclear reaction and cluster structure

International Nuclear Information System (INIS)

1985-01-01

A work shop was held in June 1984 at RCNP (Research Center for Nuclear Physics), Osaka University, to discuss theory of nuclear reactions based on studies from microscopic or cluster structure viewpoints. About forty researchers participated in this work shop and 27 paperes were presented. All these papers with English abstracts are gathered in this collective report. (Aoki, K.)

EXFOR Systems Manual Nuclear reaction Data Exchange Format

International Nuclear Information System (INIS)

McLane, V.

2000-01-01

EXFOR is an exchange format designed to allow transmission of nuclear reaction data between the members of the Nuclear Data Centers Network. This document has been written for use by the members of the Network and includes matters of procedure and protocol, as well as detailed rules for the compilation of data. Users may prefer to consult EXFOR Basics' for a brief description of the format

EXFOR SYSTEMS MANUAL NUCLEAR REACTION DATA EXCHANGE FORMAT.

Energy Technology Data Exchange (ETDEWEB)

MCLANE,V.; NUCLEAR DATA CENTER NETWORK

2000-05-19

EXFOR is an exchange format designed to allow transmission of nuclear reaction data between the members of the Nuclear Data Centers Network. This document has been written for use by the members of the Network and includes matters of procedure and protocol, as well as detailed rules for the compilation of data. Users may prefer to consult EXFOR Basics' for a brief description of the format.

Photosynthesis Is Widely Distributed among Proteobacteria as Demonstrated by the Phylogeny of PufLM Reaction Center Proteins

Directory of Open Access Journals (Sweden)

Johannes F. Imhoff

2018-01-01

Full Text Available Two different photosystems for performing bacteriochlorophyll-mediated photosynthetic energy conversion are employed in different bacterial phyla. Those bacteria employing a photosystem II type of photosynthetic apparatus include the phototrophic purple bacteria (Proteobacteria, Gemmatimonas and Chloroflexus with their photosynthetic relatives. The proteins of the photosynthetic reaction center PufL and PufM are essential components and are common to all bacteria with a type-II photosynthetic apparatus, including the anaerobic as well as the aerobic phototrophic Proteobacteria. Therefore, PufL and PufM proteins and their genes are perfect tools to evaluate the phylogeny of the photosynthetic apparatus and to study the diversity of the bacteria employing this photosystem in nature. Almost complete pufLM gene sequences and the derived protein sequences from 152 type strains and 45 additional strains of phototrophic Proteobacteria employing photosystem II were compared. The results give interesting and comprehensive insights into the phylogeny of the photosynthetic apparatus and clearly define Chromatiales, Rhodobacterales, Sphingomonadales as major groups distinct from other Alphaproteobacteria, from Betaproteobacteria and from Caulobacterales (Brevundimonas subvibrioides. A special relationship exists between the PufLM sequences of those bacteria employing bacteriochlorophyll b instead of bacteriochlorophyll a. A clear phylogenetic association of aerobic phototrophic purple bacteria to anaerobic purple bacteria according to their PufLM sequences is demonstrated indicating multiple evolutionary lines from anaerobic to aerobic phototrophic purple bacteria. The impact of pufLM gene sequences for studies on the environmental diversity of phototrophic bacteria is discussed and the possibility of their identification on the species level in environmental samples is pointed out.

Pattern formation in three-dimensional reaction-diffusion systems

Science.gov (United States)

Callahan, T. K.; Knobloch, E.

1999-08-01

Existing group theoretic analysis of pattern formation in three dimensions [T.K. Callahan, E. Knobloch, Symmetry-breaking bifurcations on cubic lattices, Nonlinearity 10 (1997) 1179-1216] is used to make specific predictions about the formation of three-dimensional patterns in two models of the Turing instability, the Brusselator model and the Lengyel-Epstein model. Spatially periodic patterns having the periodicity of the simple cubic (SC), face-centered cubic (FCC) or body-centered cubic (BCC) lattices are considered. An efficient center manifold reduction is described and used to identify parameter regimes permitting stable lamellæ, SC, FCC, double-diamond, hexagonal prism, BCC and BCCI states. Both models possess a special wavenumber k* at which the normal form coefficients take on fixed model-independent ratios and both are described by identical bifurcation diagrams. This property is generic for two-species chemical reaction-diffusion models with a single activator and inhibitor.

Theoretical studies of the nucleophilic substitution of halides and amine at a sulfonyl center.

Science.gov (United States)

Sung, Dae Dong; Kim, Tae Joon; Lee, Ikchoon

2009-06-25

Gas-phase nucleophilic substitution reactions, F(-) + CH(3)SO(2)F, Cl(-) + CH(3)SO(2)Cl, Cl(-) + CH(3)SO(2)F, and NH(3) + CH(3)SO(2)Cl, have been investigated at the B3LYP/6-311+G** and MP2/6-31+G* levels of theory. A very shallow well for the reaction intermediate in a triple-well potential energy surface (PES) was observed for the identity fluoride exchange, but double well PESs were obtained for the other three reactions with three different PES profiles. NBO analyses of the transition states showed substantial charge transfer interactions in all cases which provided a much larger amount of stabilization energy compared with the corresponding species at the carbon center of methyl halides. This difference is primarily caused by the strong electropositive nature of the sulfur center. The F-S-F axial linkage in the distorted TBP type intermediate in the identity fluoride exchange reaction exhibited a weak three-center, four-electron omega-bonding, which is considered to provide stability of the intermediate. All the reactant (RC) and product complexes (PC) have Cs symmetry. The symmetry plane bisects angles HCH (of methyl group), OSO (of sulfonyl group), and HNH (of ammonia). Vicinal charge transfer interactions between the two out-of-plane C-H, S-O, and N-H bonds provide extra stabilization to the ion-dipole complexes together with H-bond formation of in-plane H atom with the nucleophile and/or leaving group.

New Insights into the Diels-Alder Reaction of Graphene Oxide.

Science.gov (United States)

Brisebois, Patrick P; Kuss, Christian; Schougaard, Steen B; Izquierdo, Ricardo; Siaj, Mohamed

2016-04-18

Graphene oxide is regarded as a major precursor for graphene-based materials. The development of graphene oxide based derivatives with new functionalities requires a thorough understanding of its chemical reactivity, especially for canonical synthetic methods such as the Diels-Alder cycloaddition. The Diels-Alder reaction has been successfully extended with graphene oxide as a source of diene by using maleic anhydride as a dienophile, thereby outlining the presence of the cis diene present in the graphene oxide framework. This reaction provides fundamental information for understanding the exact structure and chemical nature of graphene oxide. On the basis of high-resolution (13) C-SS NMR spectra, we show evidence for the formation of new sp(3) carbon centers covalently bonded to graphene oxide following hydrolysis of the reaction product. DFT calculations are also used to show that the presence of a cis dihydroxyl and C vacancy on the surface of graphene oxide are promoting the reaction with significant negative reaction enthalpies. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analytical applications of ion/molecule reactions in a triple quadrupole mass spectrometer

International Nuclear Information System (INIS)

Kinter, M.T.

1986-01-01

The development of triple quadrupole mass spectrometers as a means of performing tandem mass spectrometry has provided a versatile instrument on which the ion/molecule reactions of a mass selected ion can be studied. This dissertation details the application of ion/molecule reactions in a triple quadrupole to two analytical problems. Part I. Ion/Molecule Reactions of Ammonia with Translationally Excited C 2 H 5 O + /Ions. The ability to impart low center-of-mass translational energies, which upon collision are converted into internal energy, allows the observation of reactions that require energy input. In addition, the systematic variation of the ion kinetic energy, often referred to as energy-resolved mass spectrometer, adds another dimension to the mass spectrum and can allow the observation of thresholds for reactions requiring energy input. This investigation develops methods for determining these thresholds. Part 2. The Use of Ion/Molecule Reactions in selected Reaction Monitoring GC/MSD/MS Analyses. An approach to improving the selectivity of an analysis is to improve the selectivity of the detection method. In GC/MS, one method has been to monitor a selected fragmentation reaction, either metastable or collisionally activated, in a selected reaction monitoring (SRM) analysis. This develops the use of ion/molecule reactions for selected reaction monitoring analyses

Study of reactions for the production of uranium titrafluoride and uranium hexafluoride

International Nuclear Information System (INIS)

Guzella, M.F.R.

1985-01-01

The main production processes of uranium hexafluoride in pilot plants and industrial facilities are described. The known reactions confirmed in laboratory experiments that lead to Uf 6 or other intermediate fluorides are discussed. For the purpose of determining a thermodinamically feasible reaction involving the sulfur hexafluoride as fluorinating agent, a mock-up facility was designed and constructed as a part of the R and D work planned at the CDTN (Nuclebras Center for Nuclear Technology Development). IN the uranium tatrafluoride synthesis employing U 3 O 8 and SF 6 several experimental parameters are studied. The reaction time, gasflow, temperature and stoechiometic relations among reagents are described in detail. (Author) [pt

Selenocysteine in thiol/disulfide-like exchange reactions.

Science.gov (United States)

Hondal, Robert J; Marino, Stefano M; Gladyshev, Vadim N

2013-05-01

Among trace elements used as cofactors in enzymes, selenium is unique in that it is incorporated into proteins co-translationally in the form of an amino acid, selenocysteine (Sec). Sec differs from cysteine (Cys) by only one atom (selenium versus sulfur), yet this switch dramatically influences important aspects of enzyme reactivity. The main focus of this review is an updated and critical discussion on how Sec might be used to accelerate thiol/disulfide-like exchange reactions in natural selenoenzymes, compared with their Cys-containing homologs. We discuss in detail three major aspects associated with thiol/disulfide exchange reactions: (i) nucleophilicity of the attacking thiolate (or selenolate); (ii) electrophilicity of the center sulfur (or selenium) atom; and (iii) stability of the leaving group (sulfur or selenium). In all these cases, we analyze the benefits that selenium might provide in these types of reactions. It is the biological thiol oxidoreductase-like function that benefits from the use of Sec, since Sec functions to chemically accelerate the rate of these reactions. We review various hypotheses that could help explain why Sec is used in enzymes, particularly with regard to competitive chemical advantages provided by the presence of the selenium atom in enzymes. Ultimately, these chemical advantages must be connected to biological functions of Sec.

A model for calculation of RCS pressure during reflux boiling under reduced inventory conditions and its assessment against PKL data

International Nuclear Information System (INIS)

Palmrose, D.E.; Mandl, R.

1991-01-01

Based on the occurrence of a number of plant incidents during low power and shutdown operating conditions, the Nuclear Regulatory Commission (NRC) has initiated several programs to better quantify risk during these periods. One specific issue of interest is the loss of residual heat removal (RHR) under reduced coolant inventory conditions. This issue is also of interest in the Federal Republic of Germany and an experiment was performed in the integral PKL-3 experimental facility at Siemens-KWU to supply applicable data. Recently, an effort has been undertaken at the Idaho National Engineering Laboratory (INEL) to identify and analyze the important thermal-hydraulic phenomena in pressurized water reactors following loss of vital AC power and consequent loss of the RHR system during reduced inventory operation. The thermal-hydraulic response of a nuclear steam supply system (NSSS) with a closed reactor coolant system (RCS) to loss of residual heat removal cooling capability is investigated in this report. The specific processes investigated include: boiling of the coolant in the core and reflux condensation in the steam generators, the corresponding pressure increase in the reactor coolant system, the heat transfer mechanisms on the primary and secondary sides of the steam generators, the effects of air or other noncondensible gas on the heat transfer processes, and void fraction distributions on the primary side of the system. Mathematical models of these physical processes were developed and validated against experimental data from the PKL 3B 4.5 Experiment

Scandium(III) catalysis of transimination reactions. Independent and constitutionally coupled reversible processes.

Science.gov (United States)

Giuseppone, Nicolas; Schmitt, Jean-Louis; Schwartz, Evan; Lehn, Jean-Marie

2005-04-20

Sc(OTf)(3) efficiently catalyzes the self-sufficient transimination reaction between various types of C=N bonds in organic solvents, with turnover frequencies up to 3600 h(-)(1) and rate accelerations up to 6 x 10(5). The mechanism of the crossover reaction in mixtures of amines and imines is studied, comparing parallel individual reactions with coupled equilibria. The intrinsic kinetic parameters for isolated reactions cannot simply be added up when several components are mixed, and the behavior of the system agrees with the presence of a unique mediator that constitutes the core of a network of competing reactions. In mixed systems, every single amine or imine competes for the same central hub, in accordance with their binding affinity for the catalyst metal ion center. More generally, the study extends the basic principles of constitutional dynamic chemistry to interconnected chemical transformations and provides a step toward dynamic systems of increasing complexity.

Inhibition of Heme Peroxidase During Phenol Derivatives Oxidation. Possible Molecular Cloaking of the Active Center

Directory of Open Access Journals (Sweden)

Juozas Kulys

2005-10-01

Full Text Available Abstract: Ab initio quantum chemical calculations have been applied to the study of the molecular structure of phenol derivatives and oligomers produced during peroxidasecatalyzed oxidation. The interaction of substrates and oligomers with Arthromyces ramosus peroxidase was analyzed by docking methods. The most possible interaction site of oligomers is an active center of the peroxidase. The complexation energy increases with increasing oligomer length. However, the complexed oligomers do not form a precise (for the reaction hydrogen bonding network in the active center of the enzyme. It seems likely that strong but non productive docking of the oligomers determines peroxidase inhibition during the reaction.

A facile and expedient one-pot three-component reaction leading to ...

Indian Academy of Sciences (India)

Sci. Vol. 124, No. 5, September 2012, pp. 1007–1012. c Indian Academy of Sciences. A facile and expedient one-pot three-component reaction leading to multifunctionalized stabilized phosphorus ylides. ZAHRA HASSANI. ∗ and ZEINAB ESFANDIARPOUR. Department of New Materials, International Center for Science, ...

Laser Spot Detection Based on Reaction Diffusion

Directory of Open Access Journals (Sweden)

Alejandro Vázquez-Otero

2016-03-01

Full Text Available Center-location of a laser spot is a problem of interest when the laser is used for processing and performing measurements. Measurement quality depends on correctly determining the location of the laser spot. Hence, improving and proposing algorithms for the correct location of the spots are fundamental issues in laser-based measurements. In this paper we introduce a Reaction Diffusion (RD system as the main computational framework for robustly finding laser spot centers. The method presented is compared with a conventional approach for locating laser spots, and the experimental results indicate that RD-based computation generates reliable and precise solutions. These results confirm the flexibility of the new computational paradigm based on RD systems for addressing problems that can be reduced to a set of geometric operations.

Plume-Free Stream Interaction Heating Effects During Orion Crew Module Reentry

Science.gov (United States)

Marichalar, J.; Lumpkin, F.; Boyles, K.

2012-01-01

During reentry of the Orion Crew Module (CM), vehicle attitude control will be performed by firing reaction control system (RCS) thrusters. Simulation of RCS plumes and their interaction with the oncoming flow has been difficult for the analysis community due to the large scarf angles of the RCS thrusters and the unsteady nature of the Orion capsule backshell environments. The model for the aerothermal database has thus relied on wind tunnel test data to capture the heating effects of thruster plume interactions with the freestream. These data are only valid for the continuum flow regime of the reentry trajectory. A Direct Simulation Monte Carlo (DSMC) analysis was performed to study the vehicle heating effects that result from the RCS thruster plume interaction with the oncoming freestream flow at high altitudes during Orion CM reentry. The study was performed with the DSMC Analysis Code (DAC). The inflow boundary conditions for the jets were obtained from Data Parallel Line Relaxation (DPLR) computational fluid dynamics (CFD) solutions. Simulations were performed for the roll, yaw, pitch-up and pitch-down jets at altitudes of 105 km, 125 km and 160 km as well as vacuum conditions. For comparison purposes (see Figure 1), the freestream conditions were based on previous DAC simulations performed without active RCS to populate the aerodynamic database for the Orion CM. Other inputs to the analysis included a constant Orbital reentry velocity of 7.5 km/s and angle of attack of 160 degrees. The results of the study showed that the interaction effects decrease quickly with increasing altitude. Also, jets with highly scarfed nozzles cause more severe heating compared to the nozzles with lower scarf angles. The difficulty of performing these simulations was based on the maximum number density and the ratio of number densities between the freestream and the plume for each simulation. The lowest altitude solutions required a substantial amount of computational resources

Medication Desensitization: Characterization of Outcomes and Risk Factors for Reactions.

Science.gov (United States)

Murray, Taryn S; Rice, Todd W; Wheeler, Arthur P; Phillips, Elizabeth J; Dworski, Ryszard T; Stollings, Joanna L

2016-03-01

Although its mechanisms are poorly understood, desensitization has been used to induce a temporary state of immune unresponsiveness in patients who have IgE-, non-IgE-, or pharmacologically mediated reactions when a drug has no alternatives. The purpose of this study was to characterize the outcomes and identify risk factors for reactions during drug desensitization. A retrospective review of electronic medical records of adult patients undergoing drug desensitization from January 1, 2011, to December 31, 2013, was conducted in 2 intensive care units at a tertiary medical center. We used multivariate analysis to determine if specified risk factors were associated with reacting during the desensitization. Reactions were classified according to the pretest probability prior to desensitization, and then, reactions during desensitization were classified based on the occurrence of cutaneous reactions as follows: successful with no reaction, mild reaction, moderate reaction, or failed. Failure could result from any systemic allergic or cutaneous reaction resulting in procedure termination. The desensitizations were also assessed to determine if the patient required de-escalation secondary to a reaction. A total of 88 desensitizations were performed in 69 patients. Desensitization was completed with no cutaneous reaction in 85% of patients. No baseline characteristic, medication class (P = 0.46), or indication for desensitization (P = 0.59) was associated with having a reaction. Reported histories of urticaria (P desensitization. However, neither history of urticaria nor labored breathing was independently associated with having a reaction in multivariate analysis (OR = 0.979, 95% CI = 0.325-2.952, P = 0.970, and OR = 1.626, 95% CI = 0.536-4.931, P = 0.739, respectively). Drug desensitization is safe for patients who have no alternative for therapy. Reported allergy histories of urticaria and labored breathing are both associated with having a reaction during the

Pattern of Adverse Drug Reactions in Children Attending the Department of Pediatrics in a Tertiary Care Center: A Prospective Observational Study

Directory of Open Access Journals (Sweden)

Kishour Kumar Digra

2015-01-01

Full Text Available AIM To study the pattern of various adverse drug reactions (ADRs occurring in children attending the Department of Pediatrics, SMGS Hospital, Jammu over 1 year. Subjects and Methods This was a prospective study, with study population of patients attending Department of Pediatrics over a period of 1 year. A structured format was used to enroll the participants. A pilot study was conducted to test the suitability of the format and feasibility of the study. The study was carried out to review various pattern of ADRs by using the Naranjo probability scale, and severity was assessed by using the Hartwig severity scale. ADRs were classified according to the classification used by the Adverse Drug Reaction Monitoring Center, Central Drugs Standard Control Organization, New Delhi, India. Results In the present study, 104 patients were found to have developed acute drug reactions. Among these, 83.6% were type B, 14.42% type A, and 1.92% were type U. Furthermore, 25.96% ADRs were due to anticonvulsants, followed by antibiotics (22.11%, antipyretics (11.53%, vaccination (8.65%, steroids (6.73%, decongestants (5.67%, snake antivenom and antiemetics (3.84%, and fluids, insulin, and antacids (1.92%. The patients’ dermatological system was involved in 67.30%, followed by the central nervous system (CNS in 11.53% patients. Renal system was involved in 6.73% patients. Cardiac, musculoskeletal, metabolic, and other systems were involved in 4.80%, 3.84%, 2.88%, and 0.96%, respectively. According to the Hartwig severity scale of ADRs, 64.4% patients had moderate ADRs, 29.8% patients had severe ADRs, and 5.76% had mild ADRs. In the present study, 64.4% patients expressed moderate severity, whereas 29.8% expressed high severity and 5.76% expressed mild ADRs. Conclusion ADRs were seen in 71% of the patients between 1 and 5 years of age, 26% in the age group of 5–10 years, and 3% were more than 10 years old. Anticonvulsants (25.96% and antibiotics (22.11% were

Los Alamos Neutron Science Center (LANSCE) Nuclear Science Facilities

Energy Technology Data Exchange (ETDEWEB)

Nelson, Ronald Owen [Los Alamos National Laboratory; Wender, Steve [Los Alamos National Laboratory

2015-06-19

The Los Alamos Neutron Science Center (LANSCE) facilities for Nuclear Science consist of a high-energy "white" neutron source (Target 4) with 6 flight paths, three low-energy nuclear science flight paths at the Lujan Center, and a proton reaction area. The neutron beams produced at the Target 4 complement those produced at the Lujan Center because they are of much higher energy and have shorter pulse widths. The neutron sources are driven by the 800-MeV proton beam of the LANSCE linear accelerator. With these facilities, LANSCE is able to deliver neutrons with energies ranging from a milli-electron volt to several hundreds of MeV, as well as proton beams with a wide range of energy, time and intensity characteristics. The facilities, instruments and research programs are described briefly.

Correlation of paramagnetic states and molecular structure in bacterial photosynthetic reaction centers: The symmetry of the primary electron donor in Rhodopseudomonas viridis and Rhodobacter sphaeroides R-26

International Nuclear Information System (INIS)

Norris, J.R.; Budil, D.E.; Gast, P.; Chang, C.H.; El-Kabbani, O.; Schiffer, M.

1989-01-01

The orientation of the principal axes of the primary electron donor triplet state measured in single crystals of photosynthetic reaction centers is compared to the x-ray structures of the bacteria Rhodobacter (Rb.) sphaeroides R-26 and Rhodopseudomonas (Rps.) viridis. The primary donor of Rps. viridis is significantly different from that of Rb. sphaeroides. The measured directions of the axes indicate that triplet excitation is almost completely localized on the L-subunit half of the dimer in Rps. viridis but is more symmetrically distributed on the dimeric donor in Rb. sphaeroides R-26. The large reduction of the zero field splitting parameters relative to monomeric bacteriochlorophyll triplet in vitro suggests significant participation of asymmetrical charge transfer electronic configurations in the special pair triplet state of both organisms

Theoretical investigation of the gas-phase reactions of CrO(+) with ethylene.

Science.gov (United States)

Scupp, Thomas M; Dudley, Timothy J

2010-01-21

The potential energy surfaces associated with the reactions of chromium oxide cation (CrO(+)) with ethylene have been characterized using density functional, coupled-cluster, and multireference methods. Our calculations show that the most probable reaction involves the formation of acetaldehyde and Cr(+) via a hydride transfer involving the metal center. Our calculations support previous experimental hypotheses that a four-membered ring intermediate plays an important role in the reactivity of the system. We have also characterized a number of viable reaction pathways that lead to other products, including ethylene oxide. Due to the experimental observation that CrO(+) can activate carbon-carbon bonds, a reaction pathway involving C-C bond cleavage has also been characterized. Since many of the reactions involve a change in the spin state in going from reactants to products, locations of these spin surface crossings are presented and discussed. The applicability of methods based on Hartree-Fock orbitals is also discussed.

Non-Toxic Orbital Maneuvering System Engine Development

Science.gov (United States)

Green, Christopher; Claflin, Scott; Maeding, Chris; Butas, John

1999-01-01

Recent results using the Aestus engine operated with LOx/ethanol propellant are presented. An experimental program at Rocketdyne Propulsion and Power is underway to adapt this engine for the Boeing Reusable Space Systems Division non-toxic Orbital Maneuvering System/Reaction control System (OMS/RCS) system. Daimler-Chrysler Aerospace designed the Aestus as an nitrogen tetroxide/monomethyl hydrazine (NTO/MMH) upper-stage engine for the Ariane 5. The non-toxic OMS/RCS system's preliminary design requires a LOx/ethanol (O2/C2H5OH) engine that operates with a mixture ratio of 1.8, a specific impulse of 323 seconds, and fits within the original OMS design envelope. This paper describes current efforts to meet these requirements including, investigating engine performance using LOx/ethanol, developing the en-ine system sizing package, and meeting the vehicle operation parameters. Data from hot-fire testing are also presented and discussed.

Seismic analysis of the reactor coolant system of PWR nuclear power plants

International Nuclear Information System (INIS)

Borsoi, L.; Sollogoub, P.

1986-01-01

For safety considerations, seismic analyses are performed of the Reactor Coolant System (R.C.S.) of PWR Plants. After a brief description of the R.C.S. and R.C.S. operation, the paper presents the two types of analysis used to determine the effect of earthquake on the R.C.S.: modal spectral analysis and nonlinear time history analysis. The paper finally shows how seismic loadings are combined with other types of loadings and illustrates how the consideration of seismic loads affects R.C.S. design [fr

Insights into the π-p → ηn reaction mechanism

International Nuclear Information System (INIS)

Durand, J.; Julia-Diaz, B.; Julia-Diaz, B.; Julia-Diaz, B.; Lee, T.S.H.; Sato, T.; Lee, T.S.H.; Sato, T.

2009-01-01

A dynamical coupled-channels formalism is used to investigate the eta-meson production mechanism on the proton induced by pions, in the total center-of-mass energy region from threshold up to 2 GeV. We show how and why studying exclusively total cross section data might turn out to be misleading in pinning down the reaction mechanism. (authors)

The Inverse Demand Oxa-Diels-Alder Reaction of Resorcinarenes: An Experimental and Theoretical Analysis of Regioselectivity and Diastereoselectivity.

Science.gov (United States)

Stefańska, Karolina; Jędrzejewska, Hanna; Wierzbicki, Michał; Szumna, Agnieszka; Iwanek, Waldemar

2016-07-15

The Diels-Alder reaction enables introduction of new functionalities onto the resorcinarene skeleton with simultaneous generation of new stereogenic centers and expansion of the internal cavity. We present highly regio- and diastereoselective inverse electron demand oxa-Diels-Alder reactions of resorcinarene ortho-quinone methide with benzofuran and indene, each generating 12 new stereogenic centers. The mechanism and reasons for regioselectivity and diastereoselectivity were analyzed using theoretical calculations (NBO charges, Fukui functions, transition state energies, and thermodynamic stability of the products). Enantiomers were separated, and their configurations were determined by comparison of experimental and theoretical electronic circular dichroism spectra.

Social categorization and fear reactions to the September 11th terrorist attacks

NARCIS (Netherlands)

Dumont, M.; Yzerbyt, V.Y.; Wigboldus, D.H.J.; Gordijn, E.H.

2003-01-01

Two experiments were run in The Netherlands and Belgium 1 week after the terrorist attacks against the World Trade Center in New York on September 11, 2001. The aim was to investigate whether social categorization affected emotional reactions, behavioral tendencies, and actual behaviors. Results

Studying astrophysical reactions with low-energy RI beams at CRIB

Directory of Open Access Journals (Sweden)

Yamaguchi H.

2016-01-01

Full Text Available Studies on nuclear astrophysics, nuclear structure, and other interests have been performed using the radioactive-isotope (RI beams at the low-energy RI beam separator CRIB, operated by Center for Nuclear Study (CNS, the University of Tokyo. A typical measurement performed at CRIB is the elastic resonant scattering with the inverse kinematics. One recent experiment was on the α resonant scattering with 7Li and 7Be beams. This study is related to the astrophysical 7Li/7Be(α,γ reactions, important at hot p-p chain and νp-process in supernovae. There have also been measurements based on other experimental methods. The first THM measurement using an RI beam has been performed at CRIB, to study the 18F(p, α15O reaction at astrophysical energies via the three body reaction 2H(18F, α15On. The 18F(p, α 15O reaction rate is crucial to understand the 511-keV γ-ray production in nova explosion phenomena, and we successfully evaluated the reaction cross section at novae temperature and below experimentally for the first time.

The incidence and features of systemic reactions to skin prick tests.

Science.gov (United States)

Sellaturay, Priya; Nasser, Shuaib; Ewan, Pamela

2015-09-01

Skin prick testing (SPT) has been regarded as a safe procedure with few systemic reactions. To evaluate the rate of systemic reactions and their associations after SPT in the largest population to date. In this study reactions were recorded prospectively in a specialist UK allergy clinic for 6 years (2007-2013). An estimated 31,000 patients underwent SPT. Twenty-four patients (age range 7 months to 56 years, mean 23.5 years, 17 female patients, 12 with asthma) had systemic reactions. The rate of systemic reactions to SPT was 0.077%. The likely allergens causing the reaction were foods (18; peanut, 7; walnut, 1; Brazil nut, 2; pistachio, 1; lupin, 1; cow's milk, 2; shrimp, 1; spinach, 1; legume, 1; soy, 1), aeroallergens (4; rabbit, 1; rat, 1; ragwort, 1; grass pollen, 1), wasp venom (1), and Tazocin (1). The causative SPT wheal was larger than 8 mm in 75%. The reaction to Tazocin was severe, with anaphylaxis occurring minutes after SPT. Reactions were treated immediately in the clinic and did not require further medical care. In this largest single-center study, the rate of systemic reactions after SPT was 77 per 100,000 patients. It is the first study to identify foods as a common and important cause (75%), with nuts posing the highest risk. This study reports the first systemic reaction to venom SPT and the first anaphylactic reaction after drug SPT. There was an association with a history of severe reactions and large skin test reaction. There are risks, albeit small, when undertaking SPT. Copyright © 2015 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Increasing insect reactions in Alaska: is this related to changing climate?

Science.gov (United States)

Demain, Jeffrey G; Gessner, Bradford D; McLaughlin, Joseph B; Sikes, Derek S; Foote, J Timothy

2009-01-01

In 2006, Fairbanks, AK, reported its first cases of fatal anaphylaxis as a result of Hymenoptera stings concurrent with an increase in insect reactions observed throughout the state. This study was designed to determine whether Alaska medical visits for insect reactions have increased. We conducted a retrospective review of three independent patient databases in Alaska to identify trends of patients seeking medical care for adverse reactions after insect-related events. For each database, an insect reaction was defined as a claim for the International Classification of Diseases, Ninth Edition (ICD-9), codes E9053, E906.4, and 989.5. Increases in insect reactions in each region were compared with temperature changes in the same region. Each database revealed a statistically significant trend in patients seeking care for insect reactions. Fairbanks Memorial Hospital Emergency Department reported a fourfold increase in patients in 2006 compared with previous years (1992-2005). The Allergy, Asthma, and Immunology Center of Alaska reported a threefold increase in patients from 1999 to 2002 to 2003 to 2007. A retrospective review of the Alaska Medicaid database from 1999 to 2006 showed increases in medical claims for insect reactions among all regions, with the largest percentage of increases occurring in the most northern areas. Increases in insect reactions in Alaska have occurred after increases in annual and winter temperatures, and these findings may be causally related.

Drift-tube studies of ion-molecule reactions at low collision energies

International Nuclear Information System (INIS)

Chatterjee, B.K.

1988-01-01

This thesis presents experimental studies of ion-molecule reactions at low collision energies using two drift tube mass spectrometer apparatus. The reactions studied are (i) proton transfer from HeH + to ArH + , (ii) charge and ion transfer reactions of O 2 2+ with NO, CO 2 , Ne and O 2 + ( 4 π u ) with CO 2 , (iii) oxidation reactions of Zr + and ZrO + with NO, CO 2 and O 2 , (iv) vibrational quenching reactions of H 3 + with He, (v) termolecular clustering reactions of H 2 CN + and H 2 CN + (HCN) (with He as the third body), (vi) three body association reactions of H + and D + with He (with He as the third body) and (vii) termolecular association reaction of NO + with NO (with Ne as third body). All the reactions were studied at thermal energies (at room temperature), reactions of O 2 2+ with NO and CO 2 , Zr + with NO/CO 2 /O 2 were also studied at center-of-mass energies higher than thermal and the association reactions of H 2 CN + /H 2 CN + (HCN) with HCN and H + /D + with He were studied at low temperatures. In addition, the thesis presents model calculations for the sweep-out effect which is an instrumental effect. A super Langevin rate constant is introduced which is a higher-order correction to the Langevin model. A theoretical model for the three-body ion-atom association rate constant is presented in the appendix of the thesis

Study of reactions for the obtention of uranium tetrafluoride and hexafluoride

International Nuclear Information System (INIS)

Guzella, M.F.R.

1984-01-01

Based on an exhaustive bibliographical review, the main production processes of uranium hexafluoride in pilot plants and industrial facilities are described. The known reactions, confirmed in laboratory experiments, that lead to UF 6 or other intermediate fluorides, are presented and discussed. In order to determine a new thermodinamically feasible reaction involving the sulfur hexafluoride as fluorinating agent, a mock-up facility was designed and constructed as part of the R and D work planned at CDTN (NUCLEBRAS Center for Nuclear Technology Development, MG - Brazil). For the UF 4 synthesis employing U 3 O 8 and SF 6 , several experimental parameters were studied. The reaction time, gas flow, temperature and stoichiometric relations among reagents are described in detail. Suggestions for further investigations regarding this new reagent are made. (Author) [pt

Stealth metamaterial objects characterized in the far field by Radar Cross Section measurements

DEFF Research Database (Denmark)

Iwaszczuk, Krzysztof; Fan, K.; Strikwerda, A. C.

Reflection spectra and radar cross sections (RCS) at terahertz frequencies are measured on structures incorporating absorbing metamaterials. Reduction of the RCS by the factor of 375 at the resonant frequencies is observed.......Reflection spectra and radar cross sections (RCS) at terahertz frequencies are measured on structures incorporating absorbing metamaterials. Reduction of the RCS by the factor of 375 at the resonant frequencies is observed....

X-ray and EPR study of reactions between B{sub 4}C and TiO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Kakazey, M. [CIICAP/FCQI, Universidad Autonoma del Estado de Morelos, Cuernavaca, Morelos (Mexico)]. E-mail: kakazey@hotmail.com; Vlasova, M. [CIICAP/FCQI, Universidad Autonoma del Estado de Morelos, Cuernavaca, Morelos (Mexico); Gonzalez-Rodriguez, J.G. [CIICAP/FCQI, Universidad Autonoma del Estado de Morelos, Cuernavaca, Morelos (Mexico); Dominguez-Patino, M. [CIICAP/FCQI, Universidad Autonoma del Estado de Morelos, Cuernavaca, Morelos (Mexico); Leder, R. [CIICAP/FCQI, Universidad Autonoma del Estado de Morelos, Cuernavaca, Morelos (Mexico)

2006-02-25

X-ray diffraction and electron paramagnetic resonance (EPR) methods have been used to study the reaction process in a system of 95 wt.% of B{sub 4}C + 5 wt.% TiO{sub 2}. The addition of TiO{sub 2} to B{sub 4}C was effective in accelerating the removal of carbon inclusions. Two types of reactions between B{sub 4}C and TiO{sub 2}, starting at temperatures {approx}1173 K, took place: (a) gas-transport exchange and (b) diffusion of Ti atoms into the B{sub 4}C lattice. These reactions modify the number and type of donor centers in the B{sub 4}C. The dependence of EPR line width on the number of donor centers in B{sub 4}C (from conditions of sample treatment) is a useful method for investigating the formation of powders and ceramics based on B{sub 4}C.

Errors in Postural Preparation Lead to Increased Choice Reaction Times for Step Initiation in Older Adults

Science.gov (United States)

Nutt, John G.; Horak, Fay B.

2011-01-01

Background. This study asked whether older adults were more likely than younger adults to err in the initial direction of their anticipatory postural adjustment (APA) prior to a step (indicating a motor program error), whether initial motor program errors accounted for reaction time differences for step initiation, and whether initial motor program errors were linked to inhibitory failure. Methods. In a stepping task with choice reaction time and simple reaction time conditions, we measured forces under the feet to quantify APA onset and step latency and we used body kinematics to quantify forward movement of center of mass and length of first step. Results. Trials with APA errors were almost three times as common for older adults as for younger adults, and they were nine times more likely in choice reaction time trials than in simple reaction time trials. In trials with APA errors, step latency was delayed, correlation between APA onset and step latency was diminished, and forward motion of the center of mass prior to the step was increased. Participants with more APA errors tended to have worse Stroop interference scores, regardless of age. Conclusions. The results support the hypothesis that findings of slow choice reaction time step initiation in older adults are attributable to inclusion of trials with incorrect initial motor preparation and that these errors are caused by deficits in response inhibition. By extension, the results also suggest that mixing of trials with correct and incorrect initial motor preparation might explain apparent choice reaction time slowing with age in upper limb tasks. PMID:21498431

Human Adipose-Derived Stem Cells Delay Retinal Degeneration in Royal College of Surgeons Rats Through Anti-Apoptotic and VEGF-Mediated Neuroprotective Effects.

Science.gov (United States)

Li, Z; Wang, J; Gao, F; Zhang, J; Tian, H; Shi, X; Lian, C; Sun, Y; Li, W; Xu, J-Y; Li, P; Zhang, J; Gao, Z; Xu, J; Wang, F; Lu, L; Xu, G-T

2016-01-01

Stem cell therapy is a promising therapeutic approach for retinal degeneration (RD). Our study investigated the effects of human adipose derived stem cell (hADSCs) on Royal College of Surgeons (RCS) rats. Green fluorescent protein (GFP)-labeled hADSCs were transplanted subretinally into RCS rats at postnatal (PN) 21 days to explore potential therapeutic effects, while adeno-associated viral vector (AAV2)-vascular endothelial growth factor (VEGF) and siVEGF-hADSCs were used to aid the mechanistic dissections. Visual function was evaluated by Electroretinogram (ERG) recording. Potential transdifferentiations were examined by Immunofluorescence (IF) and gene expressions were analyzed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Apoptotic retinal cells were detected by Terminal Deoxynucleotidyl Transferase dUTP Nick End Labeling (TUNEL) assay and the cytokines secreted by hADSCs were measured by Enzyme-linked Immunosorbent Assay (ELISA). The visual function of RCS rats began to decrease one week after their eyes opened at PN week 3 and almost lost in PN 5 weeks, accompanied by the loss of retinal outer nuclear layer (ONL). Subretinal transplantation of hADSCs significantly improved the visual function 2 weeks after the transplantation and such therapeutic effect persisted up to 8 weeks after the treatment (PN 11 weeks), with 3-4 rows of photoreceptors remained in the ONL and reduced apoptosis. Consistent with these phenotypic changes, the gene expression of rod photoreceptor markers Rhodopsin (Rho), Crx and Opsin (Opn1) in RCS rats showed obvious decreasing trends over time after PN 3 weeks, but were elevated with hADSC treatment. hADSC transplantation also repressed the expressions of Bax, Bak and Caspase 3, but not the expression of anti-apoptotic genes, including Bcl-2 and Bcl-XL. Finally, substantial VEGF, hepatocyte growth factor (HGF) and pigment epithelium-derived factor (PEDF) secretions from hADSCs were detected, while endogenous

Cutaneous drug reaction case reports: from the world literature.

Science.gov (United States)

2003-01-01

Skin disorders are the most common adverse reactions attributed to drugs. Any skin disorder can be imitated, induced or aggravated by drugs. To help you keep up-to-date with the very latest skin reactions occurring with both new and established drugs, this section of the journal brings you information selected from the adverse drug reaction alerting service Reactions Weekly. Reactions Weekly is the complete drug safety alerting service and summarizes information selected from over 1600 biomedical journals. This newsletter is produced by Adis International and is available in a variety of formats. Please contact your nearest Adis office for subscription details. The use of tradenames, identified by ['~'] or the use of a registered ((R)) or trade mark ( trade mark ), is for product identification purposes only and does not imply endorsement. The following case reports are selected from the very latest to be published in the world dermatology literature. Any claim of a first report has been verified by a search of AdisBase (a proprietary database of Adis International) and Medline. In addition, the World Health Organization (WHO) Adverse Drug Reactions database is also searched. This database, maintained by the Uppsala Monitoring Centre in Sweden, is the largest and most comprehensive adverse drug reaction source in the world, with information obtained from National Centers of 65 affiliate countries. Each case report is assessed for seriousness using the FDA MedWatch definition of serious (patient outcome is: death; life-threatening; hospitalization; disability; congenital anomaly; or requires intervention to prevent permanent impairment or damage).

Psychological Reactions among Patients with Chronic Hepatitis B: a Qualitative Study

Directory of Open Access Journals (Sweden)

Leila Valizadeh

2016-03-01

Full Text Available Introduction: Hepatitis B is the most prevalent type of viral hepatitis. Psychological reactions among patients with hepatitis B infection is considerably different and affects their decision about treating and following up the disease. The present study aims at explaining the psychological demonstrations experienced by these patients. Methods: In this qualitative study, a total of 18 patients with hepatitis B (8 women and 10 men were selected by purposive sampling method. Data were collected by unstructured in-depth interviews during 2014-2015 in the medical centers of three cities in Iran. All interviews were recorded, typed and analyzed by the conventional content analysis approach. Results: By analyzing the data, the main theme including psychological instability, with three sub-themes were emerged: grief reaction (stupor, denial, anger and aggression, emotional challenges (worry and apprehension, contradiction with beliefs, fear of deprivation, fear of stigma, waiting for death and prognosis ambiguity and inferiority complex (social withdrawal, sense of humiliation and embarrassment and sense of guilt and blame were acquired. Conclusion: The findings indicate that patients with hepatitis B experience various psychological reactions that need to be controlled and managed by themselves or healthcare providers. Thus, implementation of health interventions with emphasis on psychological care to prevent problems and execution of educational and consultation programs about hepatitis especially by medical centers and mass media is seems necessary.

Identification of protein W, the elusive sixth subunit of the Rhodopseudomonas palustris reaction center-light harvesting 1 core complex.