WorldWideScience
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Determination of Shooting Distance from Deformation of the ...  

Science.gov (United States)

... Descriptors : *TERMINAL BALLISTICS, *WOUND BALLISTICS, VELOCITY, CONVERSION, REPRINTS, TISSUES(BIOLOGY), MANUFACTURING ...

6

[Comparative study on the historical evolution of field surgery between China and Russia].  

Science.gov (United States)

Russian field surgery with its long history and distinctive characteristics has accumulated great experience in the long-time practice of warfare. Chinese field surgery was established and developed on the basis of studying from the Russian model, which opened up new areas of traffic medicine, molecular traumatology and assessment of biological effects on weapon destruction and carried out in-depth research on wound ballistics, blast injury, burns and combined injury etc. through decades of construction with continuous development and innovation, and a series of major achievements have been made in these fields. By making comparative study on the historical evolution, structure system, characteristics of campaigns and development of society between Chinese and Russian field surgery, it can be found that there are great gaps between them and we should strengthen the research for more rapid development. PMID:20510098

2010-03-01

7

Compounding Elastomers for Use in Armament Applications.  

Science.gov (United States)

... PADS(CUSHIONS), OBTURATION(BALLISTICS), BUTYL RUBBER, COMBUSTIBLE CARTRIDGE CASES, PHOSPHORUS COMPOUNDS. ...

1977-02-01

8

Dependence of mobility on shallow localized gap states in single-crystal organic field-effect-transistors  

Energy Technology Data Exchange (ETDEWEB)

In order to optimize the performance of molecular organic electronic devices it is important to study the intermolecular density of states and charge transport mechanisms in the environment of crystalline organic material. Using this approach in Field Effect Transistors (FETs) we show that material purification improves carrier mobility and decreases density of the deep localized electronic state. We also report a general exponential energy dependence of the density of localized states in a vicinity of the mobility edge (Fermi energies up to approx7 times higher than the thermal energy (kT)) in a variety of the extensively purified molecular organic crystal FETs. This observation and the low activation energy of the order of approxkT suggest that molecular structural misplacements of the sizes that are comparable with thermal molecular modes rather than impurity deep traps play a ...

2009-12-15

9

Solution processable fluorenyl hexa-peri-hexabenzocoronenes in organic field-effect transistors and solar cells  

Energy Technology Data Exchange (ETDEWEB)

The organization of organic semiconductor molecules in the active layer of organic electronic devices has important consequences to overall device performance. This is due to the fact that molecular organization directly affects charge carrier mobility of the material. Organic field-effect transistor (OFET) performance is driven by high charge carrier mobility while bulk heterojunction (BHJ) solar cells require balanced hole and electron transport. By investigating the properties and device performance of three structural variations of the fluorenyl hexa-peri-hexabenzocoronene (FHBC) material, the importance of molecular organization to device performance was highlighted. It is clear from {sup 1}H NMR and 2D wide-angle X-ray scattering (2D WAXS) experiments that the sterically demanding 9,9-dioctylfluorene groups are preventing {pi}-{pi} intermolecular contact in the hexakis-substituted FHBC 4. For bis-substituted FHBC ...

2010-03-24

10

Wound ballistics: the management of assault rifle injuries.  

Science.gov (United States)

Studies in our wound ballistics laboratory have shown that excellent healing can occur in complicated assault rifle wounds that are free of tension and well drained. A conservative approach to debridement and excision of tissue in uncomplicated extremity wounds may be a valid and resource-saving technique. PMID:2366941

1990-05-01

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Temperature Histories of Small Metallic Fragments Trapped in Propelling Charges.  

Science.gov (United States)

Small metallic fragments can be trapped in combustible cartridge cases during manufacture and released into the interior-ballistic flow upon combustion of the case. Such particles may survive the interior-ballistic cycle and pose an ignition threat to the...

1990-01-01

12

Studies Supporting Development of a Modified Gradient Equation for Lumped-Parameter Interior Ballistic Codes.  

Science.gov (United States)

Test firings of 120-mm rounds were performed to characterize effects due to the combustible cartridge cases used. Comparisons were made between measured ballistic parameters, especially gas pressures, and those predicted by computerized simulation calcula...

1988-01-01

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An Instrumented Range Meeting the Requirements of a Wound Ballistics Small Arms Program.  

Science.gov (United States)

Instrumentation, equipment, and space requirements are outlined which would satisfy a portion of the needs of the Wound Ballistics Program of research into the terminal behavior of missiles from a variety of antipersonnel munitions (fragments, flechettes,...

1968-01-01

14

The Modeling of Boattail Intrusion in a Lumped Parameter ...  

Science.gov (United States)

... characteristics of combustible cartridge cases (Robbins, Koszoru, and Minor 1986), interior ballistic simulations using XNOVAKTC ...

1993-08-01

15

RAYMAN: A FORTRAN Computer Code for Tracing Rays ...  

Science.gov (United States)

... Descriptors : *COMPUTERIZED SIMULATION, *HUMAN BODY, *WOUND BALLISTICS, COMPUTER PROGRAMS, PROJECTILES, MATRICES ...

1977-11-01

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Multiscale Mechanical Characterization of Biomimetic Gels for ...  

Science.gov (United States)

... MECHANICAL PROPERTIES, *COPOLYMERS, *SOFT TISSUES, *GELS, *BIOMIMETICS, ISOPRENE, WOUND BALLISTICS, STYRENE PLASTICS ...

2006-11-01

17

Glass Fragment Hazard from Windows Broken by Airblast  

Science.gov (United States)

... MATHEMATICAL PREDICTION, BODIES, SKIN(ANATOMY), SONIC BOOM, BIOPHYSICS, WOUND BALLISTICS, BONE FRACTURES, SKULL. ...

1980-05-30

18

Experimental Testing of a Combustible Case for the 155mm ...  

Science.gov (United States)

... Descriptors : *INTERIOR BALLISTICS, *COMBUSTIBLE CARTRIDGE CASES, FIRING TESTS(ORDNANCE), EXPLOSIVE CHARGES, ARTILLERY ...

1982-03-01

19

Experimental Study of Flamespreading Processes in 155-mm ...  

Science.gov (United States)

... INTERIOR BALLISTICS, GRANULES, HOWITZERS, MECHANICAL WAVES, COMBUSTIBLE CARTRIDGE CASES, WEAPONS, SIMULATION. ...

1990-06-01

20

Combustible Metallic Igniter Casing for Tank Guns  

Science.gov (United States)

... TANK GUNS, GUNS, CHAMBERS, IGNITERS, INTERIOR BALLISTICS, INTERNAL PRESSURE, COMBUSTIBLE CARTRIDGE CASES, METALS. ...

1991-11-01

21

Combustible Cartridge Case Ballistic Characterization  

Science.gov (United States)

... The combustible cartridge cases currently used by the USArmy in fielded system- are manufactured by two distinct processes. ...

1990-05-01

22

The past, present, and future of wound ballistics research in China.  

Science.gov (United States)

I review the past and present of wound ballistics research in China and look toward the future of this subject. The main points area as follows: (1) Before the 1970s, China did not conduct any experimental study on wound ballistics. (2) After the 1970s, experts in ordnance and medicine closely cooperated to conduct a series of experiments or tests on wound ballistics, such as wounding effects and the mechanism of various high-speed projectiles, the treatment of the protection from firearm wounds, high quality of ammunition design, lethality criterion, blast injuries, etc. Between 1981 and 1993, four national symposia on wound ballistics were held in China. In 1988, China sponsored the Sixth International Symposium on wound Ballistics. China has made great contributions to this subject. (3) As for the future of Chinese research on wound ballistics, I suggest ...

1996-03-01

23

Field surgery on a future conventional battlefield: strategy and wound management.  

Science.gov (United States)

Most papers appearing in the surgical literature dealing with wound ballistics concern themselves with wound management in the civilian setting. The pathophysiology of modern war wounds is contrasted with ballistic wounds commonly encountered in peacetime, but it should be noted that even in peacetime the modern terrorist may have access to sophisticated military weaponry, and that patients injured by them may fall within the catchment area of any civilian hospital. Management problems associated with both wound types are highlighted; areas of controversy are discussed. The orthodox military surgical approach to ballistic wounds is expounded and defended. PMID:1996857

1991-01-01

24

Noise Characterization of Polycrystalline Silicon Thin Film Transistors for X-ray Imagers Based on Active Pixel Architectures  

UK PubMed Central (United Kingdom)

An examination of the noise of polycrystalline silicon thin film transistors, in the context of flat panel x-ray imager development, is reported. The study was conducted in the spirit of exploring...Full Text Available

2008-01-01

25

Temperature Histories of Small Metallic Fragments Trapped in ...  

Science.gov (United States)

... Abstract : Small metallic fragments can be trapped in combustible cartridge cases during manufacture and released into the interior-ballistic flow ...

1990-10-01

26

Defense Horizons. Number 18, October 2002. High-Energy ...  

Science.gov (United States)

... assets, particularly against ballistic missiles with weapons of mass ... more con- ventional missile and gun weapon systems. ... Similarly, space-based ...

2002-10-01

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29

Serial multivibrator on field effect transistors  

International Nuclear Information System (INIS)

An operating cycle of a serial multivibrator carried out on the base of field-effect transistors has been analyzed. Calculation relations for the main multivibrator parameters have been obtained, and conditions of self-excitation has been determined. Experimental data for determination of the self-oscillation excitation region have been presented. These results are in a good agreement with the experiment. The analysis of the data obtained has shown that the serial multivibrator on field-effect transistors has comparatively narrow excitation region and requires an accurate turning.

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Focused Ion Beam Induced Effects on MOS Transistor Parameters  

Energy Technology Data Exchange (ETDEWEB)

We report on recent studies of the effects of 50 keV focused ion beam (FIB) exposure on MOS transistors. We demonstrate that the changes in value of transistor parameters (such as threshold voltage, V{sub t}) are essentially the same for exposure to a Ga+ ion beam at 30 and 50 keV under the same exposure conditions. We characterize the effects of FIB exposure on test transistors fabricated in both 0.5 {micro}m and 0.225 {micro}m technologies from two different vendors. We report on the effectiveness of overlying metal layers in screening MOS transistors from FIB-induced damage and examine the importance of ion dose rate and the physical dimensions of the exposed area.

1999-07-28

31

Stationarity conditions for physicochemical processes in the interior ballistics of a gun  

Science.gov (United States)

An original method is proposed for ensuring time-invariant (stationary) interior ballistic parameters in the postprojectile space of a gun barrel. Stationarity of the parameters is achieved by investing the solid-propellant charge with highly original structures that produce the required pressure condition and linear growth of the projectile velocity. Simple relations are obtained for calculating the principal characteristics.

1995-09-01

32

Pulse synchronizing dc-to-dc converters  

Science.gov (United States)

A dc-to-dc converter has been designed which employs the synchronizing phenomenon in the transistor core multivibrator. In the proposed circuit, the voltage feedback is applied from the control transistor and the current feedback is applied from the main transistor. The operation of the converter is analyzed by the averaging method of the state space technique. The converter features small switching loss and is suitable for high frequency operation. An efficiency of more than 95% is obtained for 5 V, 3 A output at a switching frequency of 200 kHz.

1980-01-01

33

GaP/Al/sub x/Ga/sub 1-x/P heterojunction transistors for high-temperature electronic applications  

Science.gov (United States)

Useful bipolar transistor action over the temperature range from -195 to 550 /sup 0/C has been demonstrated for heterojunction bipolar transistors in the GaP/AlGaP chemical system. This represents the highest temperature at which useful bipolar solid-state transistor action has ever been demonstrated in any material. Improvements in the materials technology and in the understanding of device characteristics at high temperatures were essential to the successful fabrication of these devices. These results demonstrate that the GaP/AlGaP heterojunction system is an excellent technology for active electronic components operated at high temperatures.

1983-10-01

34

Effects on focused ion beam irradiation on MOS transistors  

Energy Technology Data Exchange (ETDEWEB)

The effects of irradiation from a focused ion beam (FIB) system on MOS transistors are reported systematically for the first time. Three MOS transistor technologies, with 0.5, 1, and 3 {mu}m minimum feature sizes and with gate oxide thicknesses ranging from 11 to 50 nm, were analyzed. Significant shifts in transistor parameters (such as threshold voltage, transconductance, and mobility) were observed following irradiation with a 30 keV Ga{sup +} focused ion beam with ion doses varying by over 5 orders of magnitude. The apparent damage mechanism (which involved the creation of interface traps, oxide trapped charge, or both) and extent of damage were different for each of the three technologies investigated.

1997-04-01

35

Twenty First Century Space Propulsion Study Addendum  

Science.gov (United States)

... Fuels", Paper AIAA-91-2451, 27th AIAA/SAE/ASME ... to-surface ballistic missiles than space-based space-to ... an effective hit-to-kill weapon without the ...

1991-06-01

36

Historical overview of wound ballistics research.  

Science.gov (United States)

Ballistics involves the study of the scientific properties of projectiles, their behavior and their terminal effects on biological tissues and other materials. Wound ballistics deals with the analysis of injuries caused by projectiles and the behavior of projectiles within human or other biological tissues. The nineteenth century witnessed the development of both of these areas with Kocher's hydrodynamic theory and the understanding of the significance of bullet deformation in causing tissue injury. The degree of traumatic disruption of tissues and organs was also related to direct energy transfer from projectiles. While subsequent research has concentrated on elucidating further mechanisms of injury, the exact cause of remote tissue damage from high energy projectiles is still the subject of ongoing research. Much of the contemporary literature regarding wound ballistics concentrates on the forensic aspects and their ...

2009-05-23

37

Consumable and Combustible Cartridge Cases.  

Science.gov (United States)

The procedure describes the procedures to be used in evaluating consumable and combustible cartridge cases. Included are ballistic tests, environmental tests, adverse condition tests, fungus resistance tests, drop tests and safety tests. (Author)

1966-01-01

38

Analysis of 210 US Army Deaths in Vietnam from July to September 1967.  

Science.gov (United States)

US Army casualty deaths in the Republic of Vietnam were analyzed to provide information on wound ballistics that may be used by interested branches of the services on the subjects of casualty reduction, wounding, mechanisms, and evaluation of hostile weap...

1970-01-01

39

[Special cases of vascular injuries by war projectiles].  

Science.gov (United States)

The author resumes what is actually known about the behaviour of war projectiles in the target (wound ballistics). This is function of their nature, their velocity, their air trajectory. The difference between lesions due to slow moving bullets and these due to projectiles with a high kinetic energy is outlined. The last ones create, through the temporary cavitation effect, lesions at distance from the residual visible tract, particularly in the vascular conduits. The therapeutic conclusions, which derive from those ballistic behaviours, are briefly described in matter of repair of vascular war injuries [Acta chir. belg., 1982, 82, 457-461]. PMID:7148288

40

[Fundamental biological model for trials of wound ballistics].  

Science.gov (United States)

The aim of our experiment was the testing of effects of common ammunition on usable and slightly accessible biological tissue thereby to create fundamental simple biological model for trials of wounded ballistic. Like objective tissue was elected biological material - pork and beef hind-limbs, pork head, pork bodily cavity. It was discovered that objective tissue is able to react to singles types of shots in all spectrum results namely simple smooth penetration wound as well as splintery fracture in dependence on kind of using ammunition. Pork hind-limb was evaluated like the most suitable biological material for given object. PMID:17172163

2006-10-01

41

Prediction of the gain degradation induced by neutrons in dipolar transistors: spectrum dependence, electrical characteristic correlations  

International Nuclear Information System (INIS)

An original evaluating method of gain degradation has been found for neutron irradiated transistors. It establishes a correlation between degradation and the product of two coefficients: spectra factor and an electrical parameter which is measured or directly deduced from manufacturer's data. Equivalence for several type of spectra (fission, 14MeV and degradation sensitivity to electrical parameters values of individual components of a batch are obtained.

1974-06-01

42

Power MOSFET transistors hardening: way to proceed and characterization  

International Nuclear Information System (INIS)

SGS-Thomson and CNES significantly hardened a power MOSFET transistor against heavy ions and cobalt 60 total dose. The influence of the major technological steps on the component radiation sensitivity has been analyzed. Then the optimization has been carried out, using booth computerized simulation and experimental data. (D.L.). 5 refs., 8 figs.

43

A simple and continuous on-state current model of polysilicon thin-film transistors for circuit simulation  

Energy Technology Data Exchange (ETDEWEB)

A simple and continuous model for the on-state current of polysilicon thin-film transistors, suitable for implementation in circuit simulators, is presented. The model includes the potential barrier at the grain boundaries, the channel length modulation and the excess current due to impact ionization. Comparison between measured output characteristics and the model shows excellent agreement over wide range of bias voltages and for devices with different gate lengths.

2005-01-01

44

Influence of high energy electron irradiation on the characteristics of polysilicon thin film transistors  

Energy Technology Data Exchange (ETDEWEB)

The influence of high energy electron (23 MeV) irradiation on the electrical characteristics of p-channel polysilicon thin film transistors (PSTFTs) was studied. The channel 220 nm thick LPCVD (low pressure chemical vapor deposition) deposited polysilicon layer was phosphorus doped by ion implantation. A 45 nm thick, thermally grown, SiO{sub 2} layer served as gate dielectric. A self-alignment technology for boron doping of the source and drain regions was used. 200 nm thick polysilicon film was deposited as a gate electrode. The obtained p-channel PSTFTs were irradiated with different high energy electron doses. Leakage currents through the gate oxide and transfer characteristics of the transistors were measured. A software model describing the field enhancement and the non-uniform current distribution at textured polysilicon/oxide interface was developed. In order to assess the irradiation-stimulated changes of gate oxide parameters the gate ...

2006-08-15

45

Influence of high energy electron irradiation on the characteristics of polysilicon thin film transistors  

International Nuclear Information System (INIS)

The influence of high energy electron (23 MeV) irradiation on the electrical characteristics of p-channel polysilicon thin film transistors (PSTFTs) was studied. The channel 220 nm thick LPCVD (low pressure chemical vapor deposition) deposited polysilicon layer was phosphorus doped by ion implantation. A 45 nm thick, thermally grown, SiO_2 layer served as gate dielectric. A self-alignment technology for boron doping of the source and drain regions was used. 200 nm thick polysilicon film was deposited as a gate electrode. The obtained p-channel PSTFTs were irradiated with different high energy electron doses. Leakage currents through the gate oxide and transfer characteristics of the transistors were measured. A software model describing the field enhancement and the non-uniform current distribution at textured polysilicon/oxide interface was developed. In order to assess the irradiation-stimulated changes of gate oxide parameters the gate oxide ...

2006-08-01

47

Characterization of All-Chromium Tunnel Junctions and Single Electron Tunneling Devices Fabricated by Direct-Writing Multilayer Technique  

CERN Document Server

We report about the fabrication and analysis of the properties of Cr/CrO_x/Cr tunnel junctions and SET transistors, prepared by different variants of direct-writing multilayer technique. In all cases, the CrO_x tunnel barriers were formed in air under ambient conditions. From the experiments on single junctions, values for the effective barrier height and thickness were derived. For the Cr/CrO_x/Cr SET transistors we achieved minimal junction areas of 17 x 60 nm^2 using a scanning transmission electron microscope for the e-beam exposure on Si_3N_4 membrane substrate. We discuss the electrical performance of the transistor samples as well as their noise behavior.

1999-01-01

48

Analysis of plasma treatment and vapor heat treatment for thin-film transistors by extracting trap densities at front and back interfaces  

International Nuclear Information System (INIS)

Hydrogen (H) plasma treatment, oxygen (O) plasma treatment and water (H_2O)-vapor heat treatment for polycrystalline-silicon (poly-Si) thin-film transistors (TFTs) have been analyzed by separately extracting trap density at a front silicon-oxide interface (D_F) and trap density at a back interface (D_B). It is found that the H plasma treatment is apt to generate D_F and D_B. The O plasma treatment reduces D_F, while the H_2O-vapor heat treatment reduces both D_F and D_B. Improvement of transistor characteristics of poly-Si TFTs depends on understanding these results.

2004-05-17

49

Transient optical and electrical effects in polymeric semiconductors  

Energy Technology Data Exchange (ETDEWEB)

Classical semiconductor physics has been continuously improving electronic components such as diodes, light-emitting diodes, solar cells and transistors based on highly purified inorganic crystals over the past decades. Organic semiconductors, notably polymeric, are a comparatively young field of research, the first light-emitting diode based on conjugated polymers having been demonstrated in 1990. Polymeric semiconductors are of tremendous interest for high-volume, low-cost manufacturing (''printed electronics''). Due to their rather simple device structure mostly comprising only one or two functional layers, polymeric diodes are much more difficult to optimize compared to small-molecular organic devices. Usually, functions such as charge injection and transport are handled by the same material which thus needs to be highly optimized. The present work contributes to expanding the knowledge on the physical ...

2009-05-28

50

Solid State Microelectrochemical Devices: Transistor and ...  

Science.gov (United States)

... Oliver, j. Egekeze, m. 7. Kennedy, JW Jorgenson, J. F. Parcher and ... 9. .:. W. Thackeray, HS White and MS Wrighton, J. Phys ... Dr. Harold H. Singerman ...

1989-10-01

51

Power electronics in electrical propulsion  

Energy Technology Data Exchange (ETDEWEB)

Various energy sources and motors of divers types can be used in electric cars with operating modes subjected to a number of particular constraints. As a result, the possible structures of the converters, that are analysed in detail, are about a dozen in number. Also considered is the use of solid-state components - thyristors, power transistors and new components.

1982-12-01

52

Fully transparent thin-film transistor devices based on SnO2 nanowires.  

Science.gov (United States)

We report on studies of field-effect transistor (FET) and transparent thin-film transistor (TFT) devices based on lightly Ta-doped SnO2 nano-wires. The nanowire-based devices exhibit uniform characteristics with average field-effect mobilities exceeding 100 cm2/V x s. Prototype nano-wire-based TFT (NW-TFT) devices on glass substrates showed excellent optical transparency and transistor performance in terms of transconductance, bias voltage range, and on/off ratio. High on-currents and field-effect mobilities were obtained from the NW-TFT devices even at low nanowire coverage. The SnO2 nanowire-based TFT approach offers a number of desirable properties such as low growth cost, high electron mobility, and optical transparency and low operation voltage, and may lead to large-scale applications of transparent electronics on diverse substrates. PMID:17595151

2007-06-27

53

Wound ballistics of gunshot injuries to the head and neck.  

Science.gov (United States)

It is important for the trauma surgeon to understand the basic principles of terminal gunshot ballistics and the study of the projectile's effect on striking soft tissue. The amount of kinetic energy dissipated to the tissue is directly related to the mass and velocity of the projectile as follows: K = MV2/2. Doubling the velocity quadruples the energy, while doubling the mass only doubles the energy. A temporary tissue cavity is produced as the striking projectile compresses the surrounding tissue; the higher the energy release, the more extensive the inapparent compressive damage. The permanent cavity that remains is the result of extrusion of tissue from the pathway of the projectile. The higher the velocity, the higher the likelihood of extensive damage. If the missile expands or fragments within the tissues, more damage will occur. PMID:6847483

1983-05-01

54

Effect of Coating of Ammonium Perchlorate with Fluorocarbon on Ballistic and Sensitivity Properties of AP/Al/HTPB Propellant  

British Library Electronic Table of Contents (United Kingdom)

Fluorocarbon polymers are used to enhance thermal stability and electrostatic protection of composite propellant compositions. A precipitation technique has been developed to coat ammonium perchlorate (AP) using a copolymer of hexafluoropropylene and vinylidene fluoride (HFP-VF) with the help of solvent-counter solvent method. The coated AP has been used to prepare propellant compositions in different ratio based on hydroxyl terminated polybutadiene (HTPB), aluminium powder along with uncoated AP and studied for viscosity build-up and visco-elastic behaviour as well as mechanical, ballistic, thermal and sensitivity properties keeping 86% solid loading. The data on viscosity build-up indicate that as the percentage of viton coated AP increases end of mix viscosity and viscosity build-up inc...

2009-01-01

55

Computational modeling of dynamic-failure mechanisms in armor/anti-armor materials. Final report, 1 Oct 88-30 Sep 91  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this project was to develop improved dynamic failure models for brittle materials (primarily ceramics). The approach to developing these failure models was to establish a database (ACERAM) in which fundamental material properties and processing information could be directly correlated with ballistic performance data. Under this contract, a comprehensive literature search was conducted, many contacts were established in the armor/anti-armor research and development community, and database development was undertaken. A more limited project was also undertaken to assess and compare the effects of material properties and penetration mechanisms on the ballistic performance of depleted uranium and tungsten alloy penetrators.

1991-02-01

56

Colour contrast in ballistic gelatine  

British Library Electronic Table of Contents (United Kingdom)

Gelatine is a reliable tissue simulant in wound ballistic experiments. The projectile penetrating the gelatine transfers energy and causes radial cracks according to the temporary cavity. Thus the crack length is a function of the energy spent in the medium. In practice the fissures are poorly contrasted for which reason an enhancement of contrast was searched. A series of six shoots with expanding bullets (9mmx19 Action-5, 9mmx19 Quick Defense 1, 5.56mmx45 Styx Action) was realized on 10% gelatine blocks at 4^oC temperature. Three blocks were marked with acryl paint on the front, three blocks were shot native. The blocks were cut in slices of 1cm thickness and optically scanned. The evaluation was performed according to Fackler's wound profile, the total crack length method and the polygo...

2010-01-01

57

Theoretical considerations for SRAM total-dose hardening  

International Nuclear Information System (INIS)

The theoretical hardness against total dose of the six-transistor SRAM cell is investigated in detail. An explicit analytical expression of the maximum tolerable threshold voltage shift is derived for two cross-coupled inverters. A numerical method is used to explore the hardness of the read and write operations. Both N- and P-channel access transistors designs are considered and their respective advantages are compared. The study points out that the radiation hardness mainly relies on the technology. Results obtained with the very robust Gate-All-Around process are finally presented.

58

Asymmetric fingered TFT structure: a new architecture for Kink effect and off-current suppression and improved stability  

International Nuclear Information System (INIS)

The asymmetric fingered structure for polysilicon thin-film transistors (AF-TFTs) is analysed in detail by combining experimental characteristics and two-dimensional numerical simulations. This structure allows an effective reduction of the kink effect and off-current, without introducing any additional series resistance. In addition, a substantial improvement in the device stability is also observed when compared to conventional TFT. The AF-TFT characteristics have been explained by considering a two transistor model.

2006-01-01

59

Results for the structural properties of random heaps of hard disks  

Energy Technology Data Exchange (ETDEWEB)

The average angle of repose and the packing density of random planar heaps of hard disks falling ballistically onto a sticky base line, where the first layer of disks is quenched in random positions, are computed for heaps with a small fixed number of gaps in the base layer. The results we find appear to be almost independent of the size of the heap and they agree with those obtained from computer simulations of large systems.

1995-01-01

60

Ballistic performance of polyurea-coated armor grade ceramic tiles  

Science.gov (United States)

The use of ceramics as energy absorbents has been studied by many researchers and some improvements in the ballistic performance of ceramic tiles have been made by coating them with different classes of materials (e.g. E-glass/epoxy, carbon-fiber/epoxy, etc.). Using ceramics for energy absorbing applications leads to a significant weight reduction of the system. Therefore, any modification to the ceramic configuration in the system which leads to more energy absorption with the same or less areal density is significant. On the other hand, polyurea has been proved to be an excellent energy dissipating agent in many applications. Inspired by this, we are studying the effect of coating ceramics with polyurea and other materials, on the energy absorption and ballistic performance of the resulting ceramic-based composites. In this study, we investigate the effect of polyurea on ballistic efficiency of ceramic tiles. To this end, ...

2010-03-01

61

Genetics, Genomics, and Molecular Biology  

Science.gov (United States)

Genetics, Genomics, and Molecular Biology USGS scientists develop and integrate new genetic and molecular techniques into systematic analyses to describe individuals and populations of fish .....

64

Stable p-channel polysilicon thin film transistors fabricated by laser doping technique  

Energy Technology Data Exchange (ETDEWEB)

In this work we present the electrical characterization of non self-aligned p-channel thin film transistors fabricated by using laser doping technique for source/drain contact formation and gate oxide deposited at room temperature by Electron Cyclotron Resonance Plasma Enhanced Chemical Vapour Deposition. These techniques are suitable for a very low temperature process for TFT fabrication. The output characteristics show a current increase at high drain voltage ('kink' effect) rather moderate, if compared to self aligned polysilicon TFTs, probably due to the gradual doping profile induced by laser doping process. After bias stress at low gate voltage and high drain voltage condition a strong reduction of kink current has been observed in the output characteristics at high drain voltage, whereas minor changes has been observed in the transfer characteristics. This behaviour is similar to what observed in n-channel Gate Overlapped Thin Film ...

2005-09-01

65

Stable p-channel polysilicon thin film transistors fabricated by laser doping technique  

International Nuclear Information System (INIS)

In this work we present the electrical characterization of non self-aligned p-channel thin film transistors fabricated by using laser doping technique for source/drain contact formation and gate oxide deposited at room temperature by Electron Cyclotron Resonance Plasma Enhanced Chemical Vapour Deposition. These techniques are suitable for a very low temperature process for TFT fabrication. The output characteristics show a current increase at high drain voltage ('kink' effect) rather moderate, if compared to self aligned polysilicon TFTs, probably due to the gradual doping profile induced by laser doping process. After bias stress at low gate voltage and high drain voltage condition a strong reduction of kink current has been observed in the output characteristics at high drain voltage, whereas minor changes has been observed in the transfer characteristics. This behaviour is similar to what observed in n-channel Gate Overlapped Thin Film ...

2005-09-01

66

GaP/Al/sub x/Ga/sub 1-x/P heterojunction bipolar junction transistor for high-temperature electronic applications  

Energy Technology Data Exchange (ETDEWEB)

Useful bipolar transistor action over the full temperature range from 78 to 823K has been demonstrated for mesa-isolated, liquid-phase epitaxial n/sup +/npn, GaP/Al/sub 0/ /sub 35/Ga/sub 0/ /sub 65/P/GaP/GaP structures. This represents both the highest temperature and the widest temperature range (745K) over which useful solid-state transistor action has ever been demonstrated in any III-V compound semiconductor system. These results imply that the GaP/Al/sub x/Ga/sub 1-x/P chemical system is an excellent materials candidate in which to base a technology for high-temperature electronics and the results also imply the very real possibility of functional solid-state devices and circuits at temperatures in excess of 500/sup 0/C.

1982-01-01

67

Electric characteristics of organic thin-film transistors and logic circuits with a ferroelectric gate insulator  

Energy Technology Data Exchange (ETDEWEB)

Organic electronic devices using a pentacene have improved importantly in the last several years. We fabricated pentacene organic thin-film transistors (OTFTs) with dielectric SiO{sub 2} and ferroelectric Pb(Zr{sub 0.3},Ti{sub 0.7})O{sub 3} (PZT) gate insulators. The organic devices using SiO{sub 2} and PZT films had the field-effect mobility of approximately 0.1 and 0.004 cm{sup 2}/V s, respectively. The drain current in the transfer curve of pentacene/PZT transistors showed a hysteresis behavior originated in a ferroelectric polarization switching. In order to investigate the polarization effect of PZT gate dielectrics in a logic circuit, the simple voltage inverter using SiO{sub 2} and PZT films was fabricated and measured by an output-input measurement. The gain of inverter at the poling-down state was approximately 7.2 and it was three times larger than the value measured at the poling-up state.

2007-07-16

68

Design of a GaAs X-ray imaging sensor with integrated HEMT readout circuitry  

CERN Document Server

A new monolithic semi-insulating (SI) GaAs sensor design for X-ray imaging applications between 10-100keV has been proposed. Monolithic pixel detectors offer a number of advantages over hybrid bump-bonded detectors, such as high device yield, low costs and are easier to produce large scale arrays. In this thesis, an investigation is made of the use of a SI GaAs wafer as both a detector element and substrate for the epitaxially grown High Electron Mobility Transistors (HEMTs). The design of the HEMT transistors, optimised for this application, were produced with the aid of the Silvaco 'Virtual Wafer Fab' simulation package. It was determined that the device characteristics would consist of a small positive threshold voltage, a low off-state drain current and high transconductance. The final HEMT transistor design, that would be integrated to a pixel detector, had a threshold voltage of 0.17V, an off-state leakage current of ...

2002-01-01

69

University of Central Lancashire - Facilities  

Wastenet

...specialised laboratories for pharmaceutics, tissue culture and molecular biology Excellent Laboratory Facilities Tissue Culture Facilities Molecular Biology Laboratory ...

70

Molecular phylogenetics and molecular dating of the New Zealand Gleicheniaceae  

Science.gov (United States)

... Symonds, G. J. Wilson, and H. Zhu. 1997. Seismic stratigraphy and structural history of the Reinga Basin and ... ...

71

The Bipolar Field-Effect Transistor: VIII. Longitudinal Gradient of Longitudinal Electric Field (Two-MOS-Gates on Pure-Base)  

International Nuclear Information System (INIS)

This paper evaluates the electric current terms from the longitudinal gradient of the longitudinal electric field in Bipolar Field-Effect-Transistors (BiFETs) with a pure base and two MOS gates operating in the unipolar (electron) current mode. These nMOS-BiFETs, known as nMOS-FinFETs, usually have electrically short channels compared with their intrinsic Debye length of about 25 #mu#m at room temperatures. These longitudinal electric current terms are important short-channel current components, which have been neglected in the computation of the long-channel electrical characteristics. This paper shows that the long-channel electrical characteristics are substantially modified by the longitudinal electrical current terms when the physical channel length is less than 100 nm.

2010-07-01

72

Silicon oxide conductivity of hydrogen ion implanted polysilicon thin film transistors  

Energy Technology Data Exchange (ETDEWEB)

The influence of hydrogen ion implantation into the channel polysilicon of polysilicon thin film transistors on gate oxide conductivity has been investigated. Data for effective tunnelling barriers at the gate oxide/channel polysilicon interface are presented. A value of 1.2eV for samples with boron doped channel polysilicon is calculated. For hydrogenated boron doped samples tunnelling barriers higher than 2.1 eV are obtained. The tunnelling barriers for phosphorus doped samples are impurity concentration dependent and decrease with increasing phosphorus concentration in the range 3 x 10{sup 17} to 3 x 10{sup 19} cm{sup -3}. (Author).

1996-10-01

73

Silicon oxide conductivity of hydrogen ion implanted polysilicon thin film transistors  

International Nuclear Information System (INIS)

The influence of hydrogen ion implantation into the channel polysilicon of polysilicon thin film transistors on gate oxide conductivity has been investigated. Data for effective tunnelling barriers at the gate oxide/channel polysilicon interface are presented. A value of 1.2eV for samples with boron doped channel polysilicon is calculated. For hydrogenated boron doped samples tunnelling barriers higher than 2.1 eV are obtained. The tunnelling barriers for phosphorus doped samples are impurity concentration dependent and decrease with increasing phosphorus concentration in the range 3 x 10"1"7 to 3 x 10"1"9 cm"-"3. (Author).

74

Optoelectronic devices grown by metallo-organic chemical vapor deposition  

International Nuclear Information System (INIS)

The metallo-organic chemical vapor deposition (MOCVD) process has been used with great success to grow AlGaAs-GaAs and InGaAsP-InGaAs-InP heterostructure materials for electronic and optoelectronic applications. Devices fabricated from Al/sub x/Ga/sub 1-x/As-GaAs heterostructures grown by MOCVD include bipolar transistors, field-effect transistors (FETs), high-mobility (or modulation-doped) FETs, large-area high-efficiency solar cells, low-threshold lasers, high-power lasers, quantum-well lasers, and visible lasers. The state of the art for the MOCFD growth of optoelectronic devices is reviewed in this paper, and some comments are made regarding future trends in the growth of these materials by MOCVD.

75

Numerical simulations of nucleate boiling in impinging jets: Applications in power electronics cooling  

Energy Technology Data Exchange (ETDEWEB)

Boiling jet impingement cooling is currently being explored to cool power electronics components. In hybrid vehicles, inverters are used for DC-AC conversion. These inverters involve a number of insulated-gate bipolar transistors (IGBTs), which are used as on/off switches. The heat dissipated in these transistors can result in heat fluxes of up to 200 W/cm{sup 2}, which makes the thermal management problem quite important. In this paper, turbulent jet impingement involving nucleate boiling is explored numerically. The framework for these computations is the CFD code FLUENT. For nucleate boiling, the Eulerian multiphase model is used. The numerical results for boiling water and R113 jets (submerged) are validated against existing experimental data in the literature. Some representative IGBT package simulations that use R134a as the cooling fluid are also presented. (author)

2008-01-15

76

Microcrystalline-Si thin-film transistors formed by using palladium silicided source/drain contact electrode  

British Library Electronic Table of Contents (United Kingdom)

Microcrystalline-Si thin-film transistors (?C-Si TFTs) formed by using the source/drain contact electrode of self-aligned palladium silicide have been investigated. Both the self-aligned palladium silicided scheme and the previous top-gate staggered structure employ two-mask process steps for fabricating ?C-Si TFTs. However, the self-aligned palladium silicided scheme would cause better device characteristics than the top-gate staggered structure, primarily due to more carrier tunneling. For a gate length of 2 ?m, as compared to the top-gate staggered scheme, this silicided scheme can result in a 40% improvement of on-state current. In addition, as the gate length is reduced to 1 ?m, considerable short-channel effect is caused for both the device schemes.

2010-01-01

77

Low-temperature polysilicon thin-film transistors fabricated from laser-processed sputtered-silicon films  

Energy Technology Data Exchange (ETDEWEB)

In an effort to develop a simple low-temperature high-performance polysilicon thin-film transistor (TFT) technology, the authors report a fabrication process featuring laser-crystallized sputtered-silicon films. This top Al-gate coplanar TFT process subjects the substrate to a maximum temperature of 300 C, and produces devices with mobilities up to 450 cm{sup 2}/Vs, on/off current ratios greater than 10{sup 7}, without using a post-hydrogenation step. They believe these results represent the highest performance TFT`s to date fabricated from sputtered silicon films.

1998-09-01

78

Length-sorted semiconducting carbon nanotubes for high-mobility thin film transistors  

British Library Electronic Table of Contents (United Kingdom)

We have developed a process for chemical purification of carbon nanotubes for solution-processable thin-film transistors (TFTs) having high mobility. Films of the purified carbon nanotubes fabricated by simple drop coating showed carrier mobilities as high as 164 cm2V?1s?1, normalized transconductances of 0.78 Sm?1, and on/off current ratios of 106. Such high performance requires the preparation of a suspension of micrometer-long and highly purified semiconducting single-walled carbon nanotubes (SWCNTs). Our purification process includes length and electronic-type selective trapping of SWCNTs using recycling gel filtration with a mixture of surfactants. The results provide an important milestone toward printed high-speed and large-area electronics with roll-to-roll and ink-jet device fabri...

2011-01-01

79

Laser-processed thin-film transistors fabricated from sputtered amorphous-silicon films  

Energy Technology Data Exchange (ETDEWEB)

Low-temperature polysilicon thin-film transistors (TFT's) have been fabricated from sputtered silicon films and characterized as a function of as-deposited hydrogen (H) content and laser crystallization fluence. A general trend is observed where TFT performance improves as the H content is lowered. Devices made from {approximately}0% H sputtered films perform similar to those made from low-pressure chemical-vapor deposition processes (LPCVD), but are fabricated at a much lower process temperature (300 C). The best sputtered TFT's had mobilities of {approximately}200 cm{sup 2}/Vs, and on/off current ratios of more than 10{sup 8}.

2000-01-01

80

Influence of mechanical bending and temperature on the threshold voltage instability of a-Si:H thin-film transistors under electrical stress  

British Library Electronic Table of Contents (United Kingdom)

This paper studies the electrical characteristics of hydrogenated amorphous silicon thin-film transistors (a-Si:H TFTs) under flat and bending situations after AC/DC stress at different temperatures. Stress temperature was varied from 77K to 400K, and threshold voltage shifts were extracted to analyze degradation mechanisms. It was found that high temperature and mechanical bending played important roles under AC stress, with an enhanced stress effect resulting in a more serious degradation. This study also discusses the dependence between the accumulated sum of bias rising and falling time and the threshold voltage shifts under AC stress.

2011-01-01

81

Fabrication of self-aligned aluminum gate polysilicon thin-film transistors using low-temperature crystallization process  

Energy Technology Data Exchange (ETDEWEB)

The performance of scanning driver circuits fabricated with self-aligned aluminum gate polysilicon thin-film transistors (TFT's) is demonstrated. After the gate electrode patterning, the fabrication process temperature is kept below 400degC to enable the use of aluminum gate electrodes. The low-temperature crystallization phenomenon, which occurs when protons are implanted simultaneously with boron or phosphorus dopants, is employed to eliminate the 600degC activation-annealing process. A maximum clock frequency of about 2.0 MHz is achieved when the driver operating voltage is 24 V and the TFT channel length is 12 [mu]m. (author).

1994-01-01

82

Fabrication of self-aligned aluminum gate polysilicon thin-film transistors using low-temperature crystallization process  

International Nuclear Information System (INIS)

The performance of scanning driver circuits fabricated with self-aligned aluminum gate polysilicon thin-film transistors (TFT's) is demonstrated. After the gate electrode patterning, the fabrication process temperature is kept below 400degC to enable the use of aluminum gate electrodes. The low-temperature crystallization phenomenon, which occurs when protons are implanted simultaneously with boron or phosphorus dopants, is employed to eliminate the 600degC activation-annealing process. A maximum clock frequency of about 2.0 MHz is achieved when the driver operating voltage is 24 V and the TFT channel length is 12 #mu#m. (author).

83

Conventional and back-side focused ion beam milling for off-axis electron holography of electrostatic potentials in transistors  

International Nuclear Information System (INIS)

Off-axis electron holography is used to characterize a linear array of transistors, which was prepared for examination in cross-sectional geometry in the transmission electron microscope (TEM) using focused ion beam (FIB) milling from the substrate side of the semiconductor device. The measured electrostatic potential is compared with results obtained from TEM specimens prepared using the more conventional 'trench' FIB geometry. The use of carbon coating to remove specimen charging effects, which result in electrostatic fringing fields outside 'trench' specimens, is demonstrated. Such fringing fields are not observed after milling from the substrate side of the device. Analysis of the measured holographic phase images suggests that the electrically inactive layer on the surface of each FIB-milled specimen typically has a thickness of 100 nm.

2005-04-01

84

Characterization of polysilicon thin-film transistors with asymmetric source/drain implantation  

Energy Technology Data Exchange (ETDEWEB)

The effect of asymmetry tilt angle ion implantation on polysilicon thin-film transistors (TFTs) device characteristics are investigated. This asymmetric source/drain (S/D) TFTs structure exhibits low leakage current and suppressed kink effect due to the relief of higher electric field near the drain junction side. It is shown that the optimal implantation tilt angle is 30 deg. in our annealing condition. And the anomalous off-state current is more than two orders of magnitude lower than that of the conventional TFTs. By well controlled the LDD region, this structure can act as a conventional structure in the on-state and the turn-on current will not be degraded. Besides, the device under severe hot carrier bias stress shows better hot carrier endurance.

2005-08-01

85

Analysis of self-heating related instability in n-channel polysilicon thin film transistors fabricated on polyimide  

Energy Technology Data Exchange (ETDEWEB)

In this work, we investigated self-heating related instability in polysilicon thin film transistors (poly-Si TFTs) fabricated on polyimide (PI) substrates. Indeed, when Joule heating becomes relevant, the temperature of the active layer can substantially rise, since the devices are fabricated on thermally insulating substrates. As a result, electrical instability is triggered and attributed to the generation of interface states, due to the Si-H bond breaking, and charge trapping into the gate insulator. In addition, by using 3-dimensional numerical simulations, coupling the thermodynamic and transport models, we analyzed the temperature distribution of the device under operating conditions and found that self-heating is more severe for devices fabricated on plastic substrates.

2009-10-01

86

[Computed tomography in gunshot trauma. I. Ballistics elements and the mechanisms of the lesions].  

Science.gov (United States)

The knowledge of wound ballistics and of wounding mechanisms is mandatory for the radiologist to interpret the CT findings of gunshot wounds. The severity of a bullet wound depends on the characteristics of the tissue it goes through, i.e., tissue elasticity, density, thickness of the wounded body part, the type of tissue, its specific gravity, internal cohesiveness and anatomical relationships, as well as on missile characteristics, i.e., mass, shape, fragmentation and deformation. Bullet velocity is certainly a major factor in wounding, but it is only one factor. Two major wounding mechanisms exist the crushing of the bullet-struck tissue (forming the permanent cavity) and radial stretching (forming a temporary cavity). Bullet "yaw" is defined as the angle between the long axis of the bullet and its flight path. The yaw is directly proportional to tissue crushing and stretching: the wider the yaw, the most severe tissue crushing and stretching and, therefore, the ...

1995-04-01

87

[Comparison of wound morphology following gunshots by machine guns and sub-machine guns].  

Science.gov (United States)

Automatic weapons such as machine guns and submachine guns are found in the German-speaking region only in special army and police units and appear accordingly rarely in homicides, suicides and accidents. In the following, the findings in two cases of death with the use of machine and submachine guns are presented. The first case was a fatal accident during shooting on a training area (current machine gun of the German army, calibre 7.62 x 51 mm), the second case was a killing during a physical conflict (submachine gun MP 40 from World War II, calibre 9 x 19 mm). In the case with the machine gun autopsy disclosed typical entry holes corresponding to the calibre, but unusually large exit wounds with tissue bridges in the wound ground, measuring 4 x 2.5 cm in diameter. By contrast, the second case (submachine gun) showed "normal" entry and exit wounds. The differences are mainly caused by deviating ballistic data of the ammunition used. They are discussed against the ...

88

Quenched large deviations for random walk in a random environment  

CERN Document Server

We take the point of view of a particle performing random walk with bounded jumps on Z^d in a stationary and ergodic random environment. We prove the quenched large deviation principle (LDP) for the pair empirical measure of the environment Markov chain. By the contraction principle, we deduce the quenched LDP for the mean velocity of the particle and obtain a variational formula for the corresponding rate function. We propose an Ansatz for the minimizer of this formula. We verify this Ansatz for nearest-neighbor walks on Z. As a separate result, we give a probabilistic formula for the ergodic invariant density of the environment Markov chain in the case of ballistic random walk with bounded jumps on Z.

2008-01-01

89

Cubature Kalman smoothers  

British Library Electronic Table of Contents (United Kingdom)

The cubature Kalman filter (CKF) is a relatively new addition to derivative-free approximate Bayesian filters built under the Gaussian assumption. This paper extends the CKF theory to address nonlinear smoothing problems; the resulting state estimator is named the fixed-interval cubature Kalman smoother (FI-CKS). Moreover, the FI-CKS is reformulated to propagate the square-root error covariances. Although algebraically equivalent to the FI-CKS, the square-root variant ensures reliable implementation when committed to embedded systems with fixed precision or when the inference problem itself is ill-conditioned. Finally, to validate the formulation, the square-root FI-CKS is applied to track a ballistic target on reentry.

2011-01-01

90

A comprehensive, numerical model of electro-thermal propulsion  

Science.gov (United States)

A computer model of an electrothermal accelerator has been developed which applies to the plasma generator as well as the gun barrel, and it for the first time allows study of the interdependent physical processes in both components simultaneously. The code comprises a 2D transient description of the plasma arc, a 2D, two-phase interior ballistics module, and a preprocessor delivering the required plasma physical data. Some results on the flow field, pressure and temperature in a typical accelerator are presented, and probable limitations on the performance of such a system are discussed. The code is to be applied to different concepts of electrothermal chemical guns.

1993-01-01

91

Cells as semantic systems  

British Library Electronic Table of Contents (United Kingdom)

Background: We consider cells as biological systems that process information by means of molecular codes. Many studies analyze cellular information processing exclusively in syntactic terms (e.g., by measuring Shannon entropy of sets of macromolecules), and abstract completely from semantic aspects that are related to the meaning of molecular information. Methods: This mini-review focusses on semantic aspects of molecular information, particularly on codes that organize the semantic dimension of molecular information. First, a general conceptual framework for describing molecular information is proposed. Second, some examples of molecular codes are presented. Third, a mathematical approach that makes the identification of molecular codes in reaction networks possible, is developed. Results...

2011-01-01

92

Total dose hardening of SIMOX buried oxides for fully depleted devices in rad-tolerant applications  

International Nuclear Information System (INIS)

A total dose hardening treatment is applied to SIMOX buried oxides. Total ionizing dose radiation testing is performed on fully-depleted transistors fabricated on both hardened and non-hardened substrates. At 200 krads x-ray dose, the front gate shift is reduced from -0.7 to -0.2 V for FETs built on the hardened wafers.

1996-07-15

93

The effects of spatial location of defect states on the switching characteristics of amorphous and polycrystalline silicon thin film transistors: A numerical simulation using AMPS 2-D  

Energy Technology Data Exchange (ETDEWEB)

We demonstrate a two-dimensional device simulator for MOSFET structures that incorporates models for defect distributions and show predicted effects on device switching performance for various spatial distributions of defects in amorphous and polycrystalline silicon.

1994-06-01

94

Report from the third workshop on future directions of solid-state chemistry: The status of solid-state chemistry and its impact in the physical sciences  

British Library Electronic Table of Contents (United Kingdom)

Executive summaryForewordPublic awareness of solid-state chemistry, or more broadly solid-state science and technology rapidly grew along with the transistor revolution and the development of the integrated circuit. We are now at the half-way point in the solid state century [Scientific American The Solid-State Century 1997;8(1) [special issue

2008-01-01

95

Influence of MeV electron irradiation on the properties of by ion implantation hydrogenated polysilicon TFTs  

Energy Technology Data Exchange (ETDEWEB)

The influence of MeV electrons irradiation on the gate oxide layers of hydrogenated polysilicon thin film transistors (TFTs) was investigated by measuring gate leakage currents and threshold voltages. The experimental data revealed a decrease of oxide trap density and increase of positive oxide charge. Improvement in the interface roughness and in the oxide quality near the bottom interface was observed.

2006-02-15

96

Influence of MeV electron irradiation on the properties of by ion implantation hydrogenated polysilicon TFTs  

International Nuclear Information System (INIS)

The influence of MeV electrons irradiation on the gate oxide layers of hydrogenated polysilicon thin film transistors (TFTs) was investigated by measuring gate leakage currents and threshold voltages. The experimental data revealed a decrease of oxide trap density and increase of positive oxide charge. Improvement in the interface roughness and in the oxide quality near the bottom interface was observed.

2006-02-01

97

Calculation of the thermal load of a high voltage cable with forced circulation of oil with the help of modeling on an analog computer  

Energy Technology Data Exchange (ETDEWEB)

Equations are compiled for thermal balance in which for simplification, no consideration is made for heat conductivity along the axis of the cable and dependence of losses, heat capacitance and heat conductivity on temperature. Equations are modeled on a transistor analog calculator 42 TA. The solution to the task on the computer produced values of maximum temperature on the cable and coordinates of the point of maximum overheating. Using the analog model, one can study other parameters of the thermal mode.

1980-01-01

98

Sulfur compound cleanup: molecular sieves for SO/sub 2/ removal  

Science.gov (United States)

The progress of laboratory studies on the removal of NO/sub x/ and SO/sub 2/ with zeolite molecular sieves is reported. The trademark of these zeolite molecular sieves is Zeolon. (LK)

1976-08-01

99

Heat Stress and Hormetin-Induced Hormesis in Human Cells: Effects on Aging, Wound Healing, Angiogenesis, and Differentiation  

UK PubMed Central (United Kingdom)

Accumulation of molecular damage and increased molecular heterogeneity are hallmarks of cellular aging. Mild stress-induced hormesis can be an effective way for reducing the accumulation of molecular...Full Text Available

100

Anchoring of a Single Molecular Rotor and Its Array on Metal Surfaces using Molecular Design and Self-Assembly  

UK PubMed Central (United Kingdom)

Functionalizing of single molecules on surfaces has manifested great potential for bottom-up construction of complex devices on a molecular scale. We discuss the growth mechanism for the initial layers...Full Text Available

101

The Combined Influence of Molecular Weight and Temperature on the ...  

Science.gov (United States)

[12] Kusy, R. P. and Turner, D. T.: Influence of molecular-weight ofpoly(methyl methacrylate)on fracture morphology in notched tension, Polymer. ...

102

REDUCTION OF INORGANIC COMPOUNDS WITH MOLECULAR HYDROGEN BY MICROCOCCUS LACTILYTICUS II.  

UK PubMed Central (United Kingdom)

Woolfolk, C. A. (University of Washington, Seattle). Reduction of inorganic compounds with molecular hydrogen by Micrococcus lactilyticus. II. Stoichiometry with inorganic...Full Text Available

1962-10-01

103

NSF-NIST Interaction in Chemistry, Materials Research, Molecular Biosciences, Bioengineering and Chemical Engineering  

Science.gov (United States)

NSF-NIST Interaction in Chemistry, Materials Research, Molecular Biosciences, Bioengineering, and ... Laboratory (CSTL). Materials research is centralized in the Materials Science and Engineering ...

104

Molecular spectroscopy and planetary atmospheres  

Energy Technology Data Exchange (ETDEWEB)

With the improvements accomplished during the past 15 years in detection techniques and instrumentation and with the opening of space exploration, molecular spectroscopy has become a very efficient way to probe planetary atmospheres.

1984-01-01

105

Molecular Genetics and Carcinogenesis Section  

Science.gov (United States)

The Molecular Genetics and Carcinogenesis Section conducts studies using human epithelial cells to assess: activation of proto-oncogenes by chemical and physical carcinogens; inactivation and dysregulation of tumor suppressor genes by chemical and physical

106

Molecular Cloning and Characterization of Three Novel Lysozyme-Like Genes, Predominantly Expressed in the Male ...  

Science.gov (United States)

... 041889 Molecular Cloning and Characterization of Three Novel Lysozyme-Like Genes, Predominantly Expressed in the Male Reproducti...

107

Molecular Characterization of Cryptosporidium Oocysts in Samples of Raw Surface Water and Wastewater  

UK PubMed Central (United Kingdom)

Recent molecular characterizations of Cryptosporidium parasites make it possible to differentiate the human-pathogenic Cryptosporidium parasites from those that do...Full Text Available

2001-03-01

108

IDSS: deformation invariant signatures for molecular shape comparison  

UK PubMed Central (United Kingdom)

BackgroundMany molecules of interest are flexible and undergo significant shape deformation as part of their function, but most existing methods of molecular shape comparison (MSC)...Full Text Available

109

Wide bandgap collector III-V double heterojunction bipolar transistors  

International Nuclear Information System (INIS)

This thesis is devoted to the study and development of Heterojunction Bipolar Transistors (HBTs) designed for high voltage operation. The work concentrates on the use of wide bandgap III-V semiconductor materials as the collector material and their associated properties influencing breakdown, such as impact ionisation coefficients. The work deals with issues related to incorporating a wide bandgap collector into double heterojunction structures such as conduction band discontinuities at the base-collector junction and results are presented which detail, a number of methods designed to eliminate the effects of such discontinuities. In particular the use of AlGaAs as the base material has been successful in eliminating the conduction band spike at this interface. A method of electrically injecting electrons into the collector has been employed to investigate impact ionisation in GaAs, GaInP and AlInP which has used the intrinsic gain of the devices to extract impact ...

110

Surface Fermi level engineering: Or there's more to Schottky barriers than just making diodes and field effect transistor gates  

Science.gov (United States)

Surface scientists argue about the fundamental nature of Schottky barriers, or more precisely what determines the location of the Fermi level at semiconductor surfaces and interfaces. Electrical and materials engineers worry about how to make Schottky barrier diodes and gates to field effect transistors and the control of barrier heights. There is some interesting middle ground in which the location of the surface and interface Fermi level can, for example, determine semiconductor doping characteristics during crystal growth. The authors will discuss several interesting and well known examples of doping characteristics which are still somewhat mysterious. Specifically, they address the following question: (1) why is Ge doped GaAs p type when grown from Ga melts but n type when grown from Au melts (2) why is low resistivity p type ZnSe, AlAs, and AlGaInP hard to make, and more importantly, how can the problem be fixed. In addition they describe how this concept ...

111

Polysilicon thin film transistors fabricated on low temperature plastic substrates  

Energy Technology Data Exchange (ETDEWEB)

We present device results from polysilicon thin film transistors (TFTs) fabricated at a maximum temperature of 100&hthinsp;{degree}C on polyester substrates. Critical to our success has been the development of a processing cluster tool containing chambers dedicated to laser crystallization, dopant deposition, and gate oxidation. Our TFT fabrication process integrates multiple steps in this tool, and uses the laser to crystallize deposited amorphous silicon as well as create heavily doped TFT source/drain regions. By combining laser crystallization and doping, a plasma enhanced chemical vapor deposition SiO{sub 2} layer for the gate dielectric, and postfabrication annealing at 150&hthinsp;{degree}C, we have succeeded in fabricating TFTs with I{sub ON}/I{sub OFF} ratios {gt}5{times}10{sup 5} and electron mobilities {gt}40 cm{sup 2}/V&hthinsp;s on polyester substrates. {copyright} {ital 1999 American Vacuum Society.}

1999-07-01

112

Investigations on the quality of polysilicon film-gate dielectric interface in polysilicon thin film transistors  

Energy Technology Data Exchange (ETDEWEB)

The effective electron mobility was measured as a function of surface field in polysilicon thin film transistors having the following three types of gate dielectrics; silicon dioxide deposited by low temperature (350degC) plasma-enhanced chemical vapor deposition (PECVD), low temperature (400degC) nitrogen-rich PECVD silicon nitride and high temperature (1050degC) thermally grown silicon dioxide. At low surface fields, the maximum true effective electron mobility was 40[+-]3 cm[sup 2] V[sup -1] s[sup -1] in all devices independent of the type of gate dielectric, indicating that the quality of the interface is the same. However, at high surface fields a stronger degradation of the mobility was observed in devices having the thermally grown silicon dioxide as gate dielectric, indicating the presence of surface roughness within the interfacial region. The polysilicon structure was studied by transmission electron microscopy in order to ensure that our electrical ...

1992-08-28

113

High-performance thin-film transistors fabricated using excimer laser processing and grain engineering  

Energy Technology Data Exchange (ETDEWEB)

High-performance polysilicon thin-film transistors (TFT`s) are fabricated using an excimer laser to recrystallize the undoped channel and dope the source-drain regions. Using a technique the authors call grain engineering they are able to control grain microstructure using laser parameters. Resulting polysilicon films are obtained with average grain sizes of {approximately}4--9 {micro}m in sub-100 nm thick polysilicon films without substrate heating during the laser recrystallization process. Using a simple four-mask self-aligned aluminum top-gate structure, they fabricate TFT`s in these films. By combining the grain-engineered channel polysilicon regions with laser-doped source-drain regions, TFT`s are fabricated with electron mobilities up to 260 cm{sup 2}/Vs and on/off current ratios greater than 10{sup 7} To their knowledge, these devices represent the highest performance laser-processed TFT`s reported to date fabricated without substrate heating or ...

1998-04-01

114

Fabrication and characterization of polyterpenol as an insulating layer and incorporated organic field effect transistor  

Energy Technology Data Exchange (ETDEWEB)

A non-synthetic polymer material, polyterpenol, was fabricated using a dry polymerization process namely RF plasma polymerization from an environmentally friendly monomer and its surface, optical and electrical properties investigated. Polyterpenol films were found to be transparent over the visible wavelength range, with a smooth surface with an average roughness of less than 0.4 nm and hardness of 0.4 GPa. The dielectric constant of 3.4 for polyterpenol was higher than that of the conventional polymer materials used in the organic electronic devices. The non-synthetic polymer material was then implemented as a surface modification of the gate insulator in field effect transistor (OFET) and the properties of the device were examined. In comparison to the similar device without the polymer insulating layer, the polyterpenol based OFET device showed significant improvements. The addition of the polyterpenol interlayer in the OFET shifted the threshold voltage ...

2010-08-31

115

Electrochemical sulfur passivation of visible ([similar to]670 nm) AlGaInP lasers  

Science.gov (United States)

III--V based devices such as field effect transistors, heterojunction bipolar transistors, and lasers often have surface leakage and thermal degradation problems due to surface states which pin the Fermi level to the midgap. Sulfur based passivation processes are known to improve device performance by altering surface-state densities. We have developed a voltage-controlled anodic sulfur passivation scheme using Na[sub 2]S dissolved in ethylene glycol. Our process has repeatedly produced a [similar to]25% improvement in peak output power near the catastrophic damage limit in visible ([lambda]=670 nm) AlGaInP edge-emitting lasers. The threshold current density before and after passivation, and the [ital I]--[ital V] characteristics before and after catastrophic failure, were essentially unchanged indicating that passivation raises the threshold for facet damage.

1994-07-01

116

Electrochemical sulfur passivation of visible (#approx#670 nm) AlGaInP lasers  

International Nuclear Information System (INIS)

III--V based devices such as field effect transistors, heterojunction bipolar transistors, and lasers often have surface leakage and thermal degradation problems due to surface states which pin the Fermi level to the midgap. Sulfur based passivation processes are known to improve device performance by altering surface-state densities. We have developed a voltage-controlled anodic sulfur passivation scheme using Na_2S dissolved in ethylene glycol. Our process has repeatedly produced a #approx#25% improvement in peak output power near the catastrophic damage limit in visible (#lambda#=670 nm) AlGaInP edge-emitting lasers. The threshold current density before and after passivation, and the I--V characteristics before and after catastrophic failure, were essentially unchanged indicating that passivation raises the threshold for facet damage.

117

Effects of DC gate and drain bias stresses on the degradation of excimer laser crystallized polysilicon thin film transistors  

Energy Technology Data Exchange (ETDEWEB)

The effects of gate and drain bias stresses on thin film transistors fabricated in polysilicon films crystallized using the advanced sequential lateral solidification excimer laser annealing (SLS ELA) process, which yields very elongated polysilicon grains and allows the fabrication of TFTs without grain boundary barriers to current flow, are investigated as a function of the active layer thickness and of the TFT orientation relative to the grains. The application of hot carrier stress, with a condition of V{sub GS} = V{sub DS}/2, was determined to induce threshold voltage, subthreshold swing and transconductance degradation for TFTs in thicker polysilicon films and the associated stress-induced increase in the active layer trap density was evaluated. However, this device degradation was drastically reduced for TFTs fabricated in ultra-thin films. Furthermore, the application of the same stress condition to TFTs oriented vertically to the elongated grains resulted ...

2005-01-01

118

Effects of DC gate and drain bias stresses on the degradation of excimer laser crystallized polysilicon thin film transistors  

International Nuclear Information System (INIS)

The effects of gate and drain bias stresses on thin film transistors fabricated in polysilicon films crystallized using the advanced sequential lateral solidification excimer laser annealing (SLS ELA) process, which yields very elongated polysilicon grains and allows the fabrication of TFTs without grain boundary barriers to current flow, are investigated as a function of the active layer thickness and of the TFT orientation relative to the grains. The application of hot carrier stress, with a condition of V_G_S = V_D_S/2, was determined to induce threshold voltage, subthreshold swing and transconductance degradation for TFTs in thicker polysilicon films and the associated stress-induced increase in the active layer trap density was evaluated. However, this device degradation was drastically reduced for TFTs fabricated in ultra-thin films. Furthermore, the application of the same stress condition to TFTs oriented vertically to the elongated grains resulted in ...

2005-01-01

119

[The contribution of N.I. Pirogov to the development of forensic medicine (on the occasion of his 200th birthday anniversary)].  

Science.gov (United States)

The main facets of professor N.I. Pirogov's professional activity are outlined. Forensic medicine (in the first place its organizational and practical aspects) was an integral component of his scientific and clinical work, along with applied anatomy and surgery. Landmark publications of N.I. Pirogov are listed with special reference to those concerned with forensic medical expertise of medical malpractice cases, postmortem inspection and intravital examination procedures, wound ballistics studies, the atlas of forensic pathology, etc. The surgeon and anatomist N.I. Pirogov can be justly regarded as a founder of forensic medicine in this country. PMID:21866839

120

Shock stand-off distance of a solid sphere decelerating in transonic velocity range  

British Library Electronic Table of Contents (United Kingdom)

The shock stand-off distance of a spherical model flying with transonic speeds is determined through numerical simulations. The model decelerates due to drag forces caused by the pressure and viscous shear stress at the model surface. Two-dimensional axisymmetric numerical codes with numerical grids fixed to the flying spherical model are used in the simulations. Numerically determined shock stand-off distances are compared with experimental data obtained in a previous study as well as with those obtained in our ballistic-range experiments. The numerical results and the experimental data are found to be in good agreement. In addition, the time-dependent shock stand-off distance of a decelerating model is investigated.

2011-01-01

121

Innovative methods of correlation and orbit determination for space debris  

Science.gov (United States)

We propose two algorithms to provide a full preliminary orbit of an Earth-orbiting object with a number of observations lower than the classical methods, such as those by Laplace and Gauss. The first one is the Virtual debris algorithm, based upon the admissible region, that is the set of the unknown quantities corresponding to possible orbits for a given observation for objects in Earth orbit (as opposed to both interplanetary orbits and ballistic ones). A similar method has already been successfully used in recent years for the asteroidal case. The second algorithm uses the integrals of the geocentric 2-body motion, which must have the same values at the times of the different observations for a common orbit to exist. We also discuss how to account for the perturbations of the 2-body motion, e.g., the J 2 effect.

2010-06-01

122

A Trajectory Correction based on Multi-Step Lining-up for the CLIC Main Linac  

CERN Document Server

In the CLIC main linac it is very important to minimise the trajectory excursion and consequently the emittance dilution in order to obtain the required luminosity. Several algorithms have been proposed and lately the ballistic method has proved to be very effective. The trajectory method described in this Note retains the main advantages of the latter while adding some interesting features. It is based on the separation of the unknown variables like the quadrupole misalignments, the offset and slope of the injection straight line and the misalignments of the beam position monitors (BPM). This is achieved by referring the trajectory relatively to the injection line and not to the average pre-alignment line and by using two trajectories each corresponding to slightly different quadrupole strengths. A reference straight line is then derived onto which the beam is bent by a kick obtained by moving the first quadrupole. The other quadrupoles are then aligned on that ...

1999-01-01

123

Si-JFET devices and related noise behavior under irradiation  

Energy Technology Data Exchange (ETDEWEB)

Monolithic N-channel junction field effect transistors (NJFETs) dc characteristics, small signal parameters and noise have been studied from 300 K down to cryogenic temperatures before and after irradiation with {sup 60}Co {gamma}-rays and fast neutrons (1 MeV). Radiation induced effects on dc parameters and noise are reviewed. Noise spectral density measurements performed at various temperatures have shown that the radiation induces a noise increase which is temperature and frequency dependent. (orig.). 14 refs.

1998-02-01

124

Polysilicon TFT fabrication on plastic substrates  

Energy Technology Data Exchange (ETDEWEB)

Processing techniques utilizing low temperature depositions and pulsed lasers allow the fabrication of polysilicon thin film transistors (TFT`s) on plastic substrates. By limiting the silicon, SiO2, and aluminum deposition temperatures to 100(degrees)C, and by using pulsed laser crystallization and doping of the silicon, we have demonstrated functioning polysilicon TFT`s fabricated on polyester substrates with channel mobilities of up to 7.5 cm2/V-sec and Ion/Ioff current ratios of up to 1x10(to the 6th power).

1997-08-06

125

Optical properties of proton-irradiated polymers  

Energy Technology Data Exchange (ETDEWEB)

Recently, organic semiconducting materials have gained a broad interest due to their potential for organic electronic devices such as organic light emitting diode (OLED), organic photovoltaic devices and organic field-effect transistors (OFETs). Optical properties of organic semiconducting materials are important for practical application. For example, the power conversion efficiency of organic photovoltaic devices is mainly affected by absorption properties of organic materials. Proton irradiation is one of the efficient methods to change the optical properties of organic materials. In this paper, we investigate the changes of optical properties of various polymers using the proton irradiation.

2009-05-15

126

Noise spectral density measurements of a radiation hardened CMOS process in the weak and moderate inversion  

Energy Technology Data Exchange (ETDEWEB)

The authors have measured the noise of MOS transistors of the United Technology Microelectronics Center (UTMC) 1.2 [mu]m radiation hardened CMOS P-well process from the weak to moderate inversion region. The noise power spectral densities of both NMOS and PMOS devices were measured from 1 KHz to 50 MHz. The bandwidth was chosen such that the important components of the spectral densities such as the white thermal noise and the 1/f noise could be easily resolved and analyzed in detail. In this paper the effects of different device terminal DC biases and channel geometries on the noise are described.

1992-08-01

127

CMOS/SOI hardening at 100 MRAD (SiO_2)  

International Nuclear Information System (INIS)

Hardened CMOS/SOI 29101 microprocessor, elementary cells and transistor shave been irradiated at levels between 10 Mrad(SiO_2) and 1 Grad(SiO_2) ("6"0Co and 10 keV x-rays). SIMOX buried oxide behavior in the range of 100 Mrad(SiO_2) and a channel-stopped MOS/SOI structure avoiding lateral leakage current are presented. These two items indicate the feasibility of a CMOS/SOI technology operating in the hundred Mrad(SiO_2) range.

1990-07-16

135

IJMS | Section: Physical Chemistry, Theoretical and Computational Chemistry | Special Issue: Recent Advances in Molecular Electronics  

Wastenet

...Correction Discussion Editorial Letter Opinion Review Short Note Technical Note Special Issue all A Systematic Development Method for Rational Drug Design Advances in Molecular Electronic Structure Calculations Algorithms and Molecular Sciences Antimicrobial Agents Application of Density Functional Theory Applications of Density Functional Theory Applications of Molecular Dynamics Atoms in Molecules ...

141

A Leptonic-Hadronic Model for the Afterglow of Gamma-Ray ...  

Science.gov (United States)

... PHYSICS ATOMIC AND MOLECULAR PHYSICS AND SPECTROSCOPY NUCLEAR PHYSICS & ELEMENTARY PARTICLE PHYSICS. ...

2010-11-20

142

Enhancement of long-term stability of pentacene thin-film transistors encapsulated with transparent SnO{sub 2}  

Energy Technology Data Exchange (ETDEWEB)

The long-term stability of pentacene thin-film transistors (TFTs) encapsulated with a transparent SnO{sub 2} thin-film prepared by ion beam-assisted deposition (IBAD) was investigated. After encapsulation process, our organic thin-film transistors (OTFTs) showed somewhat degraded field-effect mobility of 0.5 cm{sup 2}/(V s) that was initially 0.62 cm{sup 2}/(V s), when a buffer layer of thermally evaporated 100 nm SnO{sub 2} film had been deposited prior to IBAD process. However, the mobility was surprisingly sustained up to 1 month and then gradually degraded down to 0.35 cm{sup 2}/(V s) which was still three times higher than that of the OTFT without any encapsulation layer after 100 days in air ambient. The encapsulated OTFTs also exhibited superior on/off current ratio of over 10{sup 5} to that of the unprotected devices ({approx}10{sup 4}) which was reduced from {approx}10{sup 6} before aging. Therefore, the enhanced long-term stability of ...

2005-12-15

143

Ubiquitin over-expression phenotypes and ubiquitin gene molecular misreading during aging in Drosophila melanogaster  

UK PubMed Central (United Kingdom)

Molecular Misreading (MM) is the inaccurate conversion of genomic information into aberrant proteins. For example, when RNA polymerase II transcribes a GAGAG motif it synthesizes at low frequency RNA...Full Text Available

144

Transcription regulation of caspase-1 by R393 of HIPPI and its molecular partner HIP-1  

UK PubMed Central (United Kingdom)

Earlier we have shown that exogenous expression of HIPPI, a molecular partner of Huntingtin interacting protein HIP-1, induces apoptosis and increases expression of caspases-1, -8 and -10 in HeLa and...Full Text Available

2010-01-01

145

Stretched DNA Investigated Using Molecular-Dynamics and Quantum-Mechanical Calculations  

UK PubMed Central (United Kingdom)

AbstractWe combined atomistic molecular-dynamics simulations with quantum-mechanical calculations to investigate the sequence dependence of the stretching behavior of duplex DNA. Our...Full Text Available

2010-01-06

146

Simulation of solid molecular hydrogen - a new twist to an old problem  

British Library Electronic Table of Contents (United Kingdom)

Solid molecular orthohydrogen exhibits orientational order at low temperatures. The orthohydrogen molecules, which are quadrupoles, order in the Pa3 structure. We have simulated this ordering, and explored the behaviour under dilution by spherical parahydrogen molecules.

2010-01-01

147

Sequential Molecular and Cellular Events during Neoplastic Progression: A Mouse Syngeneic Ovarian Cancer Model1  

UK PubMed Central (United Kingdom)

AbstractStudies performed to identify early events of ovarian cancer and to establish molecular markers to support early detection and development of chemopreventive regimens have been...Full Text Available

2005-10-01

148

RXR activators molecular signalling: involvement of a PPAR?-dependent pathway in the liver and kidney, evidence for an alternative pathway in the heart  

UK PubMed Central (United Kingdom)

In this study we compared the molecular signalling elicited by rexinoids, selective retinoid X receptor (RXR)-activators, in several organs (i.e. liver, kidney,...Full Text Available

2003-03-01

149

Parallel helix bundles and ion channels: molecular modeling via simulated annealing and restrained molecular dynamics.  

UK PubMed Central (United Kingdom)

A parallel bundle of transmembrane (TM) alpha-helices surrounding a central pore is present in several classes of ion channel, including the nicotinic acetylcholine receptor (nAChR). We have modeled...Full Text Available

1994-10-01

150

Near Infrared-Fluorescent and Magnetic Resonance Imaging Molecular Probe with High T1 Relaxivity for In Vivo Multimodal Imaging  

UK PubMed Central (United Kingdom)

A new gadolinium chelating NIR fluorescent molecular probe increases T1 relaxivity of water protons, facilitating combined optical and magnetic resonance imaging.

2010-06-07

151

Molecular cloning and characterization of a hemolysin gene from Actinobacillus (Haemophilus) pleuropneumoniae.  

UK PubMed Central (United Kingdom)

This article describes the molecular cloning and expression of a hemolysin gene from a serotype 1 strain of Actinobacillus pleuropneumoniae. The hemolysin was a thermolabile protein with an apparent...Full Text Available

1989-11-01

152

Molecular biological enhancement of coal biodesulfurization. Final report, October 1988--December 1991  

Energy Technology Data Exchange (ETDEWEB)

The overall objective of this project was to use molecular genetics to develop strains of bacteria with enhanced ability to remove sulfur from coal, and to obtain data that will allow the performance and economics of a coal biodesulfurization process to be predicted. (VC)

1991-12-01

153

Molecular Dynamics Simulations of the Detoxification of Paraoxon Catalyzed by Phosphotriesterase (PTE)  

UK PubMed Central (United Kingdom)

Combined QM(PM3)/MM molecular dynamics simulations together with QM(DFT)/MM optimizations for key configurations have been performed to elucidate the enzymatic catalysis mechanism on the detoxification...Full Text Available

2009-11-30

154

In vitro analysis of nuclear mRNA export using molecular beacons for target detection  

UK PubMed Central (United Kingdom)

A detailed molecular characterization of nuclear mRNA export will require an in vitro system, allowing a biochemical reconstitution of transport. To this end, an mRNA export assay has...Full Text Available

2003-06-01

155

Educational Challenges of Molecular Life Science: Characteristics and Implications for Education and Research  

UK PubMed Central (United Kingdom)

Molecular life science is one of the fastest-growing fields of scientific and technical innovation, and biotechnology has profound effects on many aspects of daily life—often with deep, ethical...Full Text Available

2010-01-01

156

EPA On-line Tools for Site Assessment Calculation | Ecosystems...  

Science.gov (United States)

MWo = average molecular weight of fuel est. 105 g/mole for gasoline est. 165 g/mole for Jet fuel est. 230 g/mole for diesel fuel MWX = molecular weight of selected chemical...

2011-01-19

157

Computational approaches to discovering semantics in molecular biology  

Energy Technology Data Exchange (ETDEWEB)

One of the central questions of molecular biology is the discovery of the semantics of DNA. This discovery relies in a critical way on a variety of expensive computations. In order to solve these computations, both parallel computers and special-purpose hardware play a major role.

1989-07-01

158

Characteristics of the molecular diversity of the outer membrane protein A gene of Haemophilus parasuis  

UK PubMed Central (United Kingdom)

The molecular diversity of the gene encoding the outer membrane protein A (OmpA) of Haemophilus parasuis has been unclear. In this study, the structural characteristics, sequence types,...Full Text Available

2010-07-01

159

Binding of PFOS to serum albumin and DNA: insight into the molecular toxicity of perfluorochemicals  

UK PubMed Central (United Kingdom)

BackgroundHealth risk from exposure of perfluorochemicals (PFCs) to wildlife and human has been a subject of great interest for understanding their molecular mechanism of toxicity....Full Text Available

160

Alpha-Hemoglobin-Stabilizing Protein: An Erythroid Molecular Chaperone  

UK PubMed Central (United Kingdom)

Alpha-hemoglobin-stabilizing protein (AHSP) is an erythroid-specific protein that acts as a molecular chaperone for the free α chains of hemoglobin. Evidence strongly suggests...Full Text Available

2011-01-01

161

The investigation on the catalyst of methanol transformation. II. The stability of catalyst  

Energy Technology Data Exchange (ETDEWEB)

The batchwise preparation of molecular sieves for methanol conversion shows some inconsistency in catalytic stability. This is a result mainly of the change of SiO/SUB/2/Al/SUB/2O/SUB/3 in ion exchange to an H-type sieve. The dealumination during ion exchange depends upon crystal size and structural factors, which can be characterised by the cyclohexane adsorption of the raw molecular sieve. A high SiO/SUB/2/Al/SUB/2O/SUB/3 H-molecular sieve can be prepared from a molecular sieve of high adsorption capacity, this leading to a catalyst of higher stability. (4 refs.)

1984-03-01

162

Metastability of Molecular Phases of Nitrogen: Implications to the Phase Diagram  

Energy Technology Data Exchange (ETDEWEB)

Despite their simplicity, diatomic molecules of first row elements can exhibit very complex phase diagrams. Determination of the phase diagrams can be further complicated by the existence of hysteretic molecular phases that can be observed over large regions of coexistence. Here we present evidence for a previously unreported molecular phase of nitrogen existing at room temperature at least over the range of 33-74 GPa. Our measurements show that sample history may have a significant impact on the thermodynamic states accessed by the molecular nitrogen solid and, by extension, also on the established phase diagram.

2001-09-12

163

Inelastic collisions of molecular ions in the injected ion drift tube  

International Nuclear Information System (INIS)

... energy spectra inelastic scattering ion-molecule collisions mass spectrometers

1977-07-27

164

Cholera toxin binding sites in yeast triggers biochemical pathway  

International Nuclear Information System (INIS)

... e Biologia Molecular (SBBq), Sao Paulo, SP (Brazil) 217 p. APPLIED LIFE

1998-05-23

165

Applications of Cerius2, software of molecular simulation; Aplicaciones de Cerius2, software de simulacion molecular  

Energy Technology Data Exchange (ETDEWEB)

Most of the investigations have a theoretical sustenance based on molecular simulation. The area of application of molecular simulation is very wide, in the Materials Technology Department assigned to the Applied Sciences Management have been treated problems about metallic nano structures, glasses, interfaces, and molecules, to sustain and to explain some of the experimental results. Energy calculations are carried out to determine minimum energy structures, for later on to carry out calculations of some of their properties; as well as the images simulation of Electron microscopy and X-ray diffraction. (Author)

2007-07-01

166

Stereochemistry definition of small organic molecules in solution: [H-H] NOE + molecular mechanics; Okreslenie sterochemii malych czasteczek organicznych w roztworze: [H-H] NOE + mechanika molekularna  

Energy Technology Data Exchange (ETDEWEB)

Scheme of theoretical method of molecular configuration definition for small organic molecules in solution has been presented. The method bases on measurements of nuclear Overhauser effects for proton-proton interactions and molecular mechanics calculations. 3 refs, 1 fig.

1994-12-31

167

Transport properties of single-crystalline n-type semiconducting PbTe nanowires  

International Nuclear Information System (INIS)

Single-crystalline PbTe nanowires were synthesized using the chemical vapor transport method. They consisted of rock-salt structure PbTe nanocrystals uniformly grown in the [100] direction. We fabricated field-effect transistors using a single PbTe nanowire, providing evidence for its intrinsic n-type semiconductor characteristics. The values of the carrier mobility and concentration were estimated to be 0.83 cm"2 V"-"1 s"-"1 and 8.8 x 10"1"7 cm"-"3, respectively. The Seebeck coefficients (-72 ?V K"-"1) of individual nanowires were measured to show their n-type carrier-dominated thermoelectric transport properties.

2009-10-14

168

Radiation hardening of integrated circuits technologies  

International Nuclear Information System (INIS)

The radiation hardening studies started in the mid decade 1960-1970. To survive the different military or space radiative environment, a new engineering science was born, to understand the degradation of electronics components. The different solutions to improve the electronic behavior in such environments have been named 'radiation hardening' of the technologies. Improvement of existing technologies, and qualification methods have been widely studied. However, on the other hand, specific technologies were developed: the Silicon On Insulator technologies for CMOS or Bipolar. The HSOI3HD technology offers today the highest hardening level for the integration density of hundreds of thousand transistors on the same silicon. Full complex systems could be produced on a single die with a technological radiation hardening and no more system hardening.

169

REVIEW: Optical waveguide processors  

Science.gov (United States)

An analysis is made of the basic principles and methods of construction of integrated optical circuits (IOC) for data processing, which are optical waveguide processors in the integrated form. A classification is provided of IOC in accordance with the nature of the input connections to optical components and in accordance with their intended function. An analysis is made of the current status of research and development of analog IOC for handling analog and digital signals, IOC for computing technology, and switching IOC. A detailed analysis is made of IOC with different functions in data processing: spectrum analyzers and correlators, analog-digital converters, circuits for identification of data sets and for encoding of signals, threshold and multistable circuits, logic and arithmetic units, and switching arrays. Descriptions are given of IOC for optically controlled data handling: bistable purely optical logic circuits, multivibrators, flip-flops, and optical ...

1987-07-01

170

Modeling of an Inductive Adder Kicker Pulser for a Proton Radiography System  

Energy Technology Data Exchange (ETDEWEB)

An all solid-state kicker pulser for a proton radiography system has been designed. Multiple solid-state modulators stacked in an inductive-adder configuration are utilized in this kicker pulser design. Each modulator is comprised of multiple metal-oxide-semiconductor field-effect transistors (MOSFETs) which quickly switch the energy storage capacitors across a magnetic induction core. Metglas is used as the core material to minimize loss. Voltage from each modulator is inductively added by a voltage summing stalk. A circuit model of a prototype inductive adder kicker pulser modulator has been developed to predict the performance of the pulser modulator. The modeling results are compared with experimental data.

2001-06-12

171

MOVPE growth of GaAs and InP based compounds in production reactors using TBAs and TBP  

Energy Technology Data Exchange (ETDEWEB)

Today TBP and TBAs are the compounds which have the highest potential to replace the hydrides arsine and phosphine in the MOVPE process. The authors have demonstrated the entire material system Ga-In-As-P can be grown without any loss of quality using TBP and TBAs not only in one reactor, but in a complete family of reactors. These reactors range from small-scale single wafer R and D reactors to multiwafer Planetary Reactor systems. Both InP based and GaAs based materials could be grown with an excellent quality. Thus all growth processes for III-V devices--long and short wavelength lasers, LEDs, high speed transistors, etc.--can be switched to TBP and TBAs. This will drastically reduce safety hazards and lead to processes that have advantages both from the ecological and economical point of view.

1996-12-31

172

A study of different types of current mirrors using polysilicon TFTs  

Energy Technology Data Exchange (ETDEWEB)

Polysilicon thin-film technology has become of great interest due to the demand for large area electronic devices. Active matrix liquid crystal displays (AMLCDs) and active matrix organic light emitting displays (AMOLEDs) are among the fields where polysilicon thin-film transistors (poly-Si TFTs) are most commonly used. Such devices, generally, require analog signal processing. This fact makes the performance of basic analog blocks, such as current mirrors implemented with poly-Si TFTs, crucial. This paper examines the performance of various current mirror designs through simulation. Finally, a novel design of a current mirror is proposed aimed to be used in low voltage applications.

2005-01-01

173

A Logic Programming Framework for Combinational Circuit Synthesis  

CERN Document Server

Logic Programming languages and combinational circuit synthesis tools share a common "combinatorial search over logic formulae" background. This paper attempts to reconnect the two fields with a fresh look at Prolog encodings for the combinatorial objects involved in circuit synthesis. While benefiting from Prolog's fast unification algorithm and built-in backtracking mechanism, efficiency of our search algorithm is ensured by using parallel bitstring operations together with logic variable equality propagation, as a mapping mechanism from primary inputs to the leaves of candidate Leaf-DAGs implementing a combinational circuit specification. After an exhaustive expressiveness comparison of various minimal libraries, a surprising first-runner, Strict Boolean Inequality "<" together with constant function "1" also turns out to have small transistor-count implementations, competitive to NAND-only or NOR-only libraries. As a practical outcome, a more realistic ...

2008-01-01

174

Theoretical Support for the Hydrodynamic Mechanism of Pulsar Kicks  

CERN Document Server

The collapse of a massive star's core, followed by a neutrino-driven, asymmetric supernova explosion, can naturally lead to pulsar recoils and neutron star kicks. Here, we present a two-dimensional, radiation-hydrodynamic simulation in which core collapse leads to significant acceleration of a fully-formed, nascent neutron star (NS) via an induced, neutrino-driven explosion. During the explosion, a ~10% anisotropy in the low-mass, high-velocity ejecta lead to recoil of the high-mass neutron star. At the end of our simulation, the NS has achieved a velocity of ~150 km s$^{-1}$ and is accelerating at ~350 km s$^{-2}$, but has yet to reach the ballistic regime. The recoil is due almost entirely to hydrodynamical processes, with anisotropic neutrino emission contributing less than 2% to the overall kick magnitude. Since the observed distribution of neutron star kick velocities peaks at ~300-400 km s$^{-1}$, recoil due to anisotropic core-collapse supernovae provides a ...

2010-01-01

175

Noise and microresonance of critical current in Josephson junction induced by Kondo trap states  

CERN Document Server

We analyze the impact of trap states in the oxide layer of a superconducting tunnel junctions, on the fluctuation of the Josephson critical current, thus on coherence in superconducting qubits. Two mechanisms are usually considered: the current blockage due to repulsion at the occupied trap states, and the noise from electrons hopping across a trap. We extend previous studies of noninteracting traps to the case where the traps have on-site electron repulsion inside one ballistic channel. The repulsion not only allows the appropriate temperature dependence of 1/f noise, but also is a control to the coupling between the computational qubit and the spurious two-level systems inside the oxide dielectric. We use second order perturbation theory which allows to obtain analytical formulae for the interacting bound states and spectral weights, limited to small and intermediate repulsions. Remarkably, it still reproduces the main features of the model as identified from the ...

2011-01-01

176

Integral Field Unit Observations of NGC 4302: Kinematics of the Diffuse Ionized Gas Halo  

CERN Document Server

We present moderate resolution spectroscopy of extraplanar diffuse ionized gas (EDIG) emission in the edge-on spiral galaxy NGC 4302. The spectra were obtained with the SparsePak integral field unit (IFU) at the WIYN Observatory. The spectra are used to construct position-velocity (PV) diagrams at several ranges of heights above the midplane. Azimuthal velocities are directly extracted from the PV diagrams using the envelope tracing method, and indicate an extremely steep dropoff in rotational velocity with increasing height, with magnitude ~30 km/s/kpc. We find evidence for a radial variation in the velocity gradient on the receding side. We have also performed artificial observations of galaxy models in an attempt to match the PV diagrams. The results of a statistical analysis also favor a gradient of ~30 km/s/kpc. We compare these results with an entirely ballistic model of disk-halo flow, and find a strong dichotomy between the observed kinematics and those ...

2007-01-01

177

Baryonic Collapse within Dark Matter Halos and the Formation of Gaseous Galactic Disks  

CERN Document Server

This paper constructs an analytic framework for calculating the assembly of galactic disks from the collapse of gas within dark matter halos, with the goal of determining the surface density profiles. Gas parcels (baryons) fall through the potentials of dark matter halos on nearly ballistic, zero energy orbits and collect in a rotating disk. The dark matter halos have a nearly universal form, as determined previously through numerical simulations. The calculation is first carried out for a variety of pre-collapse mass distributions and rotation profiles, including polytropic spheres in hydrostatic equilibrium with the halo potential. The resulting disk surface density profiles have nearly power-law forms, with well-defined edges. This idealized scenario is generalized to include non-spherical starting states and multiple accretion events (due to gas being added to the halo via merger events). This latter complication is explored in detail and considers a log-normal ...

2006-01-01

178

Microdialysis unit for molecular weight separation  

Energy Technology Data Exchange (ETDEWEB)

The present invention relates generally to an apparatus and method for separating high molecular weight molecules from low molecular weight molecules. More specifically, the invention relates to the use of microdialysis for removal of the salt (low molecular weight molecules) from a nucleotide sample (high molecular weight molecules) for ESI-MS analysis. The dialysis or separation performance of the present invention is improved by (1) increasing dialysis temperature thereby increasing desalting efficiency and improving spectrum quality; (2) adding piperidine and imidazole to the dialysis buffer solution and reducing charge states and further increasing detection sensitivity for DNA; (3) using low concentrations of dialysis buffer and shifting the DNA negative ions to higher charge states, producing a nearly 10-fold increase in detection sensitivity and a slightly decreased desalting efficiency, or (4) ...

1999-09-21

179

Fluorescence based molecular in vivo imaging; Fluoreszenzgestuetzte molekulare Bildgebung in vivo  

Energy Technology Data Exchange (ETDEWEB)

Molecular imaging represents a modern research area that allows the in vivo study of molecular biological process kinetics using appropriate probes and visualization methods. This methodology may be defined- apart from the contrast media injection - as non-abrasive. In order to reach an in vivo molecular process imaging as accurate as possible the effects of the used probes on the biological should not be too large. The contrast media as important part of the molecular imaging can significantly contribute to the understanding of molecular processes and to the development of tailored diagnostics and therapy. Since more than 15 years PTB is developing optic imaging systems that may be used for fluorescence based visualization of tissue phantoms, small animal models and the localization of tumors and their predecessors, and for the early recognition of inflammatory processes in ...

2008-12-15

180

Wet chemical etch solutions for Al{sub x}Ga{sub 1{minus}x}P  

Science.gov (United States)

Heterostructures based on AlGaInP alloy compounds are very attractive for visible semiconductor lasers, heterojunction bipolar transistors (HBTs), and high-electron-mobility transistors (HEMTs) lattice matched to GaAs substrates. Several wet etching solutions for AlGaP of different compositions have been studied. Al{sub 0.5}Ga{sub 0.5}P is found to etch in HF, H{sub 3}PO{sub 4}, hyphosphorous acid (HOPH{sub 2}:O), HCl, KOH, and 1% Br{sub 2}-methanol (MeOH). Etching of Al{sub 0.5}Ga{sub 0.5}P in HCl is reaction limited with an activation energy of {approximately}54.4 kJ/mol. At fixed conditions, the etch rates of Al{sub x}Ga{sub 1{minus}x}P vary exponentially with x in HF and HCl, while in 1% Br{sub 2}-MeOH and mixtures of HCl and HNO{sub 3} the etch rates follow a linear dependence on AlP mole fraction. HF has been found to be a good etchant for AlGaP over InGaP or AlInP with high selectivity, while HCl is useful for the reverse case. The use ...

1996-01-01

181

High ion density plasma etching of InGaP, AlInP, and AlGaP in CH{sub 4}/H{sub 2}/Ar  

Science.gov (United States)

High microwave power (1,000 W) electron cyclotron resonance CH{sub 4}/H{sub 2}/Ar discharges produce etch rates for In{sub 0.5}Ga{sub 0.5}P, Al{sub 0.5}In{sub 0.5}P{sub 0.5}, and Al{sub 0.5}Ga{sub 0.5}P of {approximately} 2,000 {angstrom}/min at moderate RF power levels (150 W) and low pressure (1.5 mTorr). This is approximately a factor of five faster than for conventional reactive ion etching conditions where much higher ion energies are necessary. The etched surfaces are smooth over a wide range of CH{sub 4}-to-H{sub 2} ratios and microwave powers. AlInP is more resistant to preferential loss of P from the near-surface during etching than is InGaP. While the etching is ion-driven, pure Ar discharges produce rough surfaces and the CH{sub 4}/H{sub 2} is necessary in the achievement of acceptable morphologies. The InGaAlP/GaAs heterostructure is being increasingly utilized in diode lasers, light emitting diodes, field-effect transistors, and heterojunction bipolar ...

1996-03-01

182

A comprehensive understanding of the efficacy of N-Ring hardening methodologies in SiGe HBTs  

International Nuclear Information System (INIS)

We investigate the efficacy of mitigating radiation-based single event effects (SEE) within circuits incorporating SiGe heterojunction bipolar transistors (HBTs) built with an N-Ring, a transistor-level layout-based radiation hardened by design (RHBD) technique. Previous work of single-device ion-beam induced charge collection (IBICC) studies has demonstrated significant reductions in peak collector charge collection and sensitive area for charge collection; however, few circuit studies using this technique have been performed. Transient studies performed with Sandia National Laboratory's (SNL) 36 MeV 16O microbeam on voltage references built with N-Ring SiGe HBTs have shown mixed results, with reductions in the number of large voltage disruptions in addition to new sensitive areas of low-level output voltage disturbances. Similar discrepancies between device-level IBICC results and circuit measurements are found for the case of digital shift ...

2010-07-19

183

High Velocity Molecular Outflows In Massive Cluster Forming Region G10.6-0.4  

CERN Document Server

We report the arcsecond resolution SMA observations of the $^{12}$CO (2-1) transition in the massive cluster forming region G10.6-0.4. In these observations, the high velocity $^{12}$CO emission is resolved into individual outflow systems, which have a typical size scale of a few arcseconds. These molecular outflows are energetic, and are interacting with the ambient molecular gas. By inspecting the shock signatures traced by CH$_{3}$OH, SiO, and HCN emissions, we suggest that abundant star formation activities are distributed over the entire 0.5 pc scale dense molecular envelope. The star formation efficiency over one global free-fall timescale (of the 0.5 pc molecular envelope, $\\sim$10$^{5}$ years) is about a few percent. The total energy feedback of these high velocity outflows is higher than 10$^{47}$ erg, which is comparable to the total kinetic energy in the rotational motion of the dense ...

2010-01-01

184

Theory of zwitterionic molecular-based organic magnets  

British Library Electronic Table of Contents (United Kingdom)

We describe a class of organic molecular magnets based on zwitterionic molecules (betaine derivatives) possessing donor, p bridge, and acceptor groups. Using extensive electronic structure calculations we show the electronic ground-state in these systems is magnetic. In addition, we show that the large energy differences computed for the various magnetic states indicate a high Neel temperature. The quantum mechanical nature of the magnetic properties originates from the conjugated p bridge (only p electrons) in cooperation with the molecular donor-acceptor character. The exchange interactions between electron spin are strong, local, and independent on the length of the p bridge.

2011-01-01

185

The radiative decays {phi}{yields}{gamma}a{sub 0}/f{sub 0} in the molecular model for the scalar mesons  

Energy Technology Data Exchange (ETDEWEB)

We investigate the radiative decays of the {phi}-meson to the scalar mesons a{sub 0}(980) and f{sub 0}(980). We demonstrate that, contrary to earlier claims, these decays should be of the same order of magnitude for a molecular state and for a compact state and, therefore, the available experimental information is consistent with both a molecular as well as a compact structure of the scalars. Thus, the radiative decays of the {phi}-meson into scalars establish a sizable K anti K component of the scalar mesons, but do not allow to discriminate between molecules and compact states. (orig.)

2005-06-01

186

An experimental and molecular-statistical study of the adsorption of the iodobenzene, 2-iodothiophene, and isomeric iodoadamantane molecules on the graphite basal face surface  

British Library Electronic Table of Contents (United Kingdom)

The thermodynamic characteristics of adsorption of iodobenzene, 2-iodothiophene, and 1- and 2-iodoadamantanes on the surface of graphitized thermal carbon black were determined experimentally. The influence of the special features of the molecular structure of the adsorbates on the thermodynamic characteristics of adsorption was studied. The atom-atom approximation of the semiempirical molecular-statistical theory of adsorption was used to calculate the thermodynamic characteristics of adsorption of the adsorbates using the newly determined potential function parameters of pair intermolecular interaction (?(r)) of I with C atoms of the basal graphite face. For the example of isostructural monohalogenated benzenes, thiophenes, and adamantanes, a comparative analysis of the contributions of ...

2011-01-01

187

Advances in molecular biology: impact on rotavirus vaccine development.  

Science.gov (United States)

The first candidate rotavirus vaccine was a live attenuated oral vaccine made by the classical empirical method of serial passage of virus in tissue culture cells. Current tetravalent vaccine candidates that are in the final stages of efficacy testing in the United States were made by genetic reassortment. This article briefly highlights how advances in the basic understanding of the molecular biology of rotaviruses have facilitated vaccine development. New approaches for second-generation vaccines and improvements in vaccine efficacy based on further exploitation of the tools and knowledge of rotavirus molecular biology and pathogenesis are discussed. PMID:8752289

1996-09-01

188

UPS fine structures of highest occupied band in vanadyl-phthalocyanine ultrathin film  

Energy Technology Data Exchange (ETDEWEB)

Ultraviolet photoelectron spectra were measured for vanadyl phthalocyanine (VOPc) ultrathin films prepared on graphite to study effects of the molecular orientation and the electric dipole layer on the organic electronic states. VOPc has a permanent electric dipole perpendicular to the molecular plane, hence a well-defined electric dipole layer could be intentionally prepared by using the oriented monolayer. The observed binding-energy difference of the highest occupied molecular orbital (HOMO) bands between the oriented monolayer and the double layer was found to agree with the vacuum level shift, leading to a conclusion that the molecular energy level with respect to the substrate Fermi level is changed when the molecule is in the electric dipole layer.

2005-06-15

189

Towards a more functional concept of causality in cancer research  

UK PubMed Central (United Kingdom)

Advances in molecular technologies challenge the different concepts of causality in biology, epidemiology and multistage mathematical models. The lack of integration of the different aspects of causality...Full Text Available

190

Toward a theory of the initiation of cancer by ionizing radiation: the twin doublet pair model  

Science.gov (United States)

Models are proposed which explain the mechanism of action on a molecular level for the initiation of cancer by electrons or alpha particles. (ACR)

1980-01-01

191

The structure of receptor-associated protein (RAP)  

UK PubMed Central (United Kingdom)

The receptor-associated protein (RAP) is a molecular chaperone that binds tightly to certain newly synthesized LDL receptor family members in the endoplasmic reticulum (ER) and facilitates their delivery...Full Text Available

2007-08-01

193

The Structure of Plant Cell Walls  

UK PubMed Central (United Kingdom)

The molecular structure, chemical properties, and biological function of the xyloglucan polysaccharide isolated from cell walls of suspension-cultured sycamore (Acer pseudoplatanus)...Full Text Available

1973-01-01

194

The Autophagy Connection  

UK PubMed Central (United Kingdom)

For a process intimately connected to an immense range of physiological processes, the molecular understanding of macroautophagy remains far from complete. Recent large-scale studies, including...Full Text Available

2010-07-20

195

Self-Organization in Coordination-Driven Self-Assembly  

UK PubMed Central (United Kingdom)

ConspectusSelf-assembly allows for the preparation of highly complex molecular and supramolecular systems from relatively simple starting materials. Typically, self-assembled...Full Text Available

2009-10-20

197

Proteinortho: Detection of (Co-)orthologs in large-scale analysis  

UK PubMed Central (United Kingdom)

BackgroundOrthology analysis is an important part of data analysis in many areas of bioinformatics such as comparative genomics and molecular phylogenetics. The ever-increasing flood...Full Text Available

198

Production of low-molecular-weight natural rubber: Comparative assessment of a nonchemical route  

British Library Electronic Table of Contents (United Kingdom)

The use of Funtumia latex and nitrobenzene as molecular weight depressants for natural rubber was studied. Portions of a given sample of natural rubber latex were treated with these materials, and this provided a means of ascertaining the amount of Funtumia latex in a blend with natural rubber that could produce a lowering of the molecular weight equivalent to that from known concentrations of nitrobenzene in natural rubber latex. The molecular weight of the products decreased to an equilibrium value after 10 h of reaction with nitrobenzene. The calculations revealed that a 27.9% substitution of natural rubber latex (300 mL) with Funtumia rubber latex achieved the same result as nitrobenzene in the same polymer at concentrations of 0.5-2.0 wt % of the dry rubber content of the latex after ...

2007-01-01

199

Orphan GPCR research  

UK PubMed Central (United Kingdom)

Orphan G protein-coupled receptors (GPCRs) are receptors lacking endogenous ligands. Found by molecular biological analyses, they became the roots of reverse pharmacology, in which receptors are attempted...Full Text Available

2008-03-01

200

New approaches to the synthesis of aromatic polyesters  

British Library Electronic Table of Contents (United Kingdom)

A new method of the synthesis of high molecular polybutylene terephthalate (PBT) is developed with the use of Irganox 1010, tris(nonylphenyl) phosphite and hypophosphite as stabilizers and boron nitride or boron oxide as a catalyst is proposed.

2009-01-01

201

Myxoviruses Monitoring in Seals Populations  

International Science & Technology Center (ISTC)

Comparative Molecular Genetic Monitoring of Myxoviruses Circulating in Populations of Seals Phoca Caspia and Phoca Sibirica in Northern Caspian Region and Lake Baikal

202

Molecules | Special Issue: Neuroactive Compounds  

Wastenet

... Here we will summarize the synthesis, structure activity relationships , and molecular sites of action of mGluR5 PAMs. We will also review preclinical studies ...

203

Molecular cloning and analysis of lymphokines. Volume 13  

Energy Technology Data Exchange (ETDEWEB)

These proceedings collect papers on the subject of lymphokines. Topics include: DNA-cloning of mouse and human lymphokine genes, inteferons, interleukins, gene expression, tumor necrosis factors, and recombinant DNA.

1987-01-01

204

Molecular Microscopy of Brain Gangliosides: Illustrating their Distribution in Hippocampal Cell Layers  

UK PubMed Central (United Kingdom)

Gangliosides are amphiphilic molecules found in the outer layer of plasma membranes of all vertebrate...Full Text Available

2011-02-21

205

Molecular Aspects of Thyroid Hormone Actions  

UK PubMed Central (United Kingdom)

Cellular actions of thyroid hormone may be initiated within the cell nucleus, at the plasma membrane, in cytoplasm, and at the mitochondrion. Thyroid hormone nuclear receptors (TRs) mediate the biological...Full Text Available

2010-04-01

206

Mobilities of CO_2"+ and N_2O"+ in He, Ar and N_2 gases  

International Nuclear Information System (INIS)

... argon carbon dioxide cations electric fields gases helium ion mobility molecular

1976-01-01

207

Microarray-based gene expression profiles of silkworm brains  

UK PubMed Central (United Kingdom)

BackgroundMolecular genetic studies of Bombyx mori have led to profound advances in our understanding of the regulation of development. Bombyx mori brain,...Full Text Available

208

Magnetic braking of the rotation of molecular cloud cores  

International Nuclear Information System (INIS)

We investigate the magnetic braking of the core of an axisymmetric cloud whose rotation axis is parallel to the mean direction of the magnetic field. (author).

209

Liver Carcinogenesis Unit  

Science.gov (United States)

The Liver Carcinogenesis Section uses the modern technologies of molecular biology, cell biology, protein chemistry and genetics to investigate the biochemical and genetic pathways involved in human liver cancer.

210

Inhibition of barium sulfate deposition by polycarboxylates of various molecular structures  

Energy Technology Data Exchange (ETDEWEB)

To establish a relationship between the molecular structure of polycarboxylates and their growth-retarding influence on barium sulfate, seeded-suspension-growth experiments were performed at various inhibitor concentrations and pH values. Two types of polycarboxylates with a molecular structure based on their polyacrylic or maleic acid were studied. The molecular structure of these compounds were varied by particle substitution with monomers containing hydroxyl, amide, and sulfonic acid, as well as hydrophobic groups. Hydrophobic groups are detrimental to good inhibitor performance, whereas the introduction of OH, NH {sub 2}, or SO {sub 3} H groups presents opportunities to enhance the inhibitor effectiveness. The sequence in performance of the compounds on barium sulfate was compared with the sequence formerly obtained for calcium sulfate dihydrate.

1990-02-01

212

Fundamental research on explosives  

Energy Technology Data Exchange (ETDEWEB)

The nitric oxide molecule is being studied in order to understand the energetics and chemistry of initiation and detonation in liquid NO at the molecular level. An overview is presented of the work being done. (DLC)

1983-01-01

213

Efficacy and Safety of a New Vaginal Contraceptive Antimicrobial Formulation Containing High Molecular Weight ...  

Science.gov (United States)

... commercial material manufactured utilizing chlorinated hydrocarbons for the sulfonation of a long chain polystyrene to produce high ... ...

214

Dynamic Clamp Analysis of Synaptic Integration in Sympathetic Ganglia  

UK PubMed Central (United Kingdom)

Advances in modern neuroscience require the identification of principles that connect different levels of experimental analysis, from molecular mechanisms to explanations of cellular functions,...Full Text Available

2007-11-01

215

Dense and diffuse gas in dynamically active clouds  

CERN Document Server

We investigate the chemical and observational implications of repetitive transient dense core formation in molecular clouds. We allow a transient density fluctuation to form and disperse over a period of 1 Myr, tracing its chemical evolution. We then allow the same gas immediately to undergo further such formation and dispersion cycles. The chemistry of the dense gas in subsequent cycles is similar to that of the first, and a limit cycle is reached quickly (2 - 3 cycles). Enhancement of hydrocarbon abundances during a specific period of evolution is the strongest indicator of previous dynamical history. The molecular content of the diffuse background gas in the molecular cloud is expected to be strongly enhanced by the core formation and dispersion process. Such enhancement may remain for as long as 0.5 Myr. The frequency of repetitive core formation should strongly determine the level of background ...

2006-01-01

216

Comparative genomics of insect juvenile hormone biosynthesis?  

UK PubMed Central (United Kingdom)

The biosynthesis of insect juvenile hormone (JH) and its neuroendocrine control are attractive targets for chemical control of insect pests and vectors of disease. To facilitate the molecular...Full Text Available

2006-04-01

217

Cloning of the neurodegeneration gene drop-dead and characterization of additional phenotypes of its mutation  

UK PubMed Central (United Kingdom)

Mutations in the Drosophila gene drop-dead (drd) result in early adult lethality and neurodegeneration, but the molecular identity of the drd...Full Text Available

2008-01-01

218

Cellular and molecular response of human macrophages exposed to Aggregatibacter actinomycetemcomitans leukotoxin  

UK PubMed Central (United Kingdom)

Aggregatibacter (Actinobacillus) actinomycetemcomitans is a facultative anaerobic gram-negative bacterium associated with severe forms of periodontitis. A leukotoxin, which belongs...Full Text Available

2011-03-01

219

Cellular and Molecular Mechanisms of Bone Remodeling*  

UK PubMed Central (United Kingdom)

Physiological bone remodeling is a highly coordinated process responsible for bone resorption and formation and is necessary to repair damaged bone and to maintain mineral homeostasis. In addition to...Full Text Available

2010-08-13

220

Allozyme Divergence in Two Syntopic Liolaemus of the Liolaemus monticola Group (Squamata: Tropiduridae)  

Science.gov (United States)

... shareware for population genetic analysis. Molecular Biology and Biotecnology Centre, Univ. of Alberta, Canada. enlarge figure Fig. ... ...

221

Strain dependence of Si-Ge interdiffusion in epitaxial Si/Si{sub 1-y}Ge{sub y}/Si heterostructures on relaxed Si{sub 1-x}Ge{sub x} substrates  

Science.gov (United States)

The strain dependence of Si-Ge interdiffusion in epitaxial Si/Si{sub 1-y}Ge{sub y}/Si heterostructures on relaxed Si{sub 1-x}Ge{sub x} substrates has been studied using secondary ion mass spectrometry, Raman spectroscopy, and simulations. At 800 and 880 deg. C, significantly enhanced Si-Ge interdiffusion is observed in Si/Si{sub 1-y}Ge{sub y}/Si heterostructures (y=0.56, 0.45, and 0.3) with Si{sub 1-y}Ge{sub y} layers under compressive strain of -1%, compared to those under no strain. In contrast, tensile strain of 1% in Si{sub 0.70}Ge{sub 0.30} layer has no observable effect on interdiffusion in Si/Si{sub 0.70}Ge{sub 0.30}/Si heterostructures. These results are relevant to the device and process design of high mobility dual channel and heterostructure-on-insulator metal oxide semiconductor field effect transistors.

2006-01-02

222

SEM and TEM investigations of recovery and recrystallization in technically pure molybdenum; REM- und TEM-Untersuchungen von Erholung und Rekristallisation in technisch reinem Molybdaen  

Energy Technology Data Exchange (ETDEWEB)

Beside traditional applications of refractory metals, e.g. in high temperature furnace construction, lighting or glass industry, one of the most important molybdenum products nowadays are large plates which are frequently used as targets for the sputtering of molybdenum layers in thin-film transistor liquid crystal displays. For the hot rolling of the sintered pre-material, the control over the recovery and recrystallization behavior is of particular importance. Molybdenum tends to a very recovery controlled behavior during hot deformation, at which the dislocations arrange into subcell boundaries instantaneously. These pronounced recovery processes seem to consume a large amount of the stored deformation energy for the actual recrystallization. On the other hand, recovery provides the future recrystallization nuclei. For a comprehensive characterization of these microstructural processes, electron microscopy appears to be the most proper means. The aim of this ...

2011-07-15

223

Nanocontact heteroepitaxy of thin GaSb and AlGaSb films on Si substrates using ultrahigh-density nanodot seeds.  

Science.gov (United States)

A film of GaSb grown epitaxially on a Si substrate is a direct transition semiconductor useful for application as a light source in Si photonics and channel material in next-generation field effect transistors because its energy bandgap is close to the optical fibre communication wavelength and it possesses high carrier mobility. Here, we report a novel method for heteroepitaxial growth of high-quality GaSb/Si films, despite having a lattice mismatch as large as ? 12%, using elastically strain-relaxed GaSb nanodots with ultrahigh density as seed crystals for film growth. The nanodot seed crystals were grown epitaxially by restricted contact with the Si substrate through nanowindows in an ultrathin SiO(2) film on the Si substrate. A light-emitting diode containing GaSb/Si films with a thickness of ? 90 nm fabricated by this method operated at room temperature. The growth method was also used to fabricate AlGaSb films of high quality. Our method provides a new avenue ...

2011-05-17

224

Modeling of the relaxation kinetics of metastable tensile strained Si:C alloys  

Energy Technology Data Exchange (ETDEWEB)

In order to enhance the performance of CMOS transistors, embedded epitaxial layers of Si:C can be used. In the present work, Si:C layers with Carbon contents up to 1.9 at-% and in-situ Phosphorus doping up to 4 x 10{sup 20}At/cm{sup 3} have been investigated. Due to the low solubility of Carbon in Silicon (0.0004 at.-% at the melting point), all layers considered in this work are metastable and tend to relax. Since it is crucial to the application to retain the strain of those layers, the responsible mechanisms must be understood. The relaxation during thermal treatment was studied by high resolution X-ray diffraction and was found to behave differently, depending on Carbon content and Phosphorus doping concentration. In this work, we propose a relaxation mechanism based on a kick-out reaction of substitutional Carbon which is accelerated by Phosphorus content through transient enhanced diffusion. We simulate the time evolution of layer relaxation as a function of ...

2010-07-01

225

Large area, low capacitance Si(Li) detectors for high rate x-ray applications  

Energy Technology Data Exchange (ETDEWEB)

Large area, single-element Si(Li) detectors have been fabricated using a novel geometry which yields detectors with reduced capacitance and hence reduced noise at short amplifier pulse-processing times. A typical device employing the new geometry with a thickness of 6 mm and an active area of 175 mm 2 has a capacitance of only 0.5 pf, compared to 2.9 pf for a conventional planar device with equivalent dimensions. These new low capacitance detectors, used in conjunction with low capacitance field effect transistors, will result in x-ray spectrometers capable of operating at very high count rates while still maintaining excellent energy resolution. The spectral response of the low capacitance detectors to a wide range of x-ray energies at 80 K is comparable to typical state-of-the-art conventional Si(Li) devices. In addition to their low capacitance, the new devices offer other advantages over conventional detectors. Detector fabrication procedures, I-V and C-V ...

1992-10-01

226

Investigation on boron transient enhanced diffusion induced by the advanced P{sup +}/N ultra-shallow junction fabrication processes  

Energy Technology Data Exchange (ETDEWEB)

In this paper, we propose to characterize boron transient enhanced diffusion (TED) for processes currently used for P{sup +}/N ultra-shallow junctions (USJ) fabrication. Indeed, the fundamental understanding of boron diffusion for low energy boron implantation is mandatory to evaluate the scalability of such processes for the coming complementary metal-oxide-semiconductor (CMOS) transistor generations. In these experiments, we characterize the boron anomalous diffusion, thanks to boron buried marker-layers obtained by epitaxial growth. B{sup +} and BF{sub 2}{sup +} ultra-low energy (ULE) implantations and plasma doping (PLAD) using BF{sub 3} as precursor gas are carried out to compare the two techniques used for advanced USJ fabrication. Boron diffusion behaviors are analyzed via secondary ion mass spectrometry for annealing at 700 deg. C for 5 min and 15 min. Finally this paper brings some physical insights explaining the technological benefit coming from PLAD ...

2005-08-01

227

Investigation on boron transient enhanced diffusion induced by the advanced P"+/N ultra-shallow junction fabrication processes  

International Nuclear Information System (INIS)

In this paper, we propose to characterize boron transient enhanced diffusion (TED) for processes currently used for P"+/N ultra-shallow junctions (USJ) fabrication. Indeed, the fundamental understanding of boron diffusion for low energy boron implantation is mandatory to evaluate the scalability of such processes for the coming complementary metal-oxide-semiconductor (CMOS) transistor generations. In these experiments, we characterize the boron anomalous diffusion, thanks to boron buried marker-layers obtained by epitaxial growth. B"+ and BF_2"+ ultra-low energy (ULE) implantations and plasma doping (PLAD) using BF_3 as precursor gas are carried out to compare the two techniques used for advanced USJ fabrication. Boron diffusion behaviors are analyzed via secondary ion mass spectrometry for annealing at 700 deg. C for 5 min and 15 min. Finally this paper brings some physical insights explaining the technological benefit coming from PLAD technique over standard ion ...

2005-08-01

228

Impacts of additive uniaxial strain on hole mobility in bulk Si and strained-Si p-MOSFETs  

International Nuclear Information System (INIS)

Hole mobility changes under uniaxial and combinational stress in different directions are characterized and analyzed by applying additive mechanical uniaxial stress to bulk Si and SiGe-virtual-substrate-induced strained-Si (s-Si) p-MOSFETs (metal-oxide-semiconductor field-effect transistors) along (110) and (100) channel directions. In bulk Si, a mobility enhancement peak is found under uniaxial compressive strain in the low vertical field. The combination of (100) direction uniaxial tensile strain and substrate-induced biaxial tensile strain provides a higher mobility relative to the (110) direction, opposite to the situation in bulk Si. But the combinational strain experiences a gain loss at high field, which means that uniaxial compressive strain may still be a better choice. The mobility enhancement of SiGe-induced strained p-MOSFETs along the (110) direction under additive uniaxial tension is explained by the competition between biaxial and shear stress.

2009-10-01

229

High sensitivity detection and characterization of the chemical state of trace element contamination on silicon wafers  

CERN Document Server

Increasing the speed and complexity of semiconductor integrated circuits requires advanced processes that put extreme constraints on the level of metal contamination allowed on the surfaces of silicon wafers. Such contamination degrades the performance of the ultrathin SiO sub 2 gate dielectrics that form the heart of the individual transistors. Ultimately, reliability and yield are reduced to levels that must be improved before new processes can be put into production. It should be noted that much of this metal contamination occurs during the wet chemical etching and rinsing steps required for the manufacture of integrated circuits and industry is actively developing new processes that have already brought the metal contamination to levels beyond the measurement capabilities of conventional analytical techniques. The measurement of these extremely low contamination levels has required the use of synchrotron radiation total reflection X-ray fluorescence (SR-TXRF) ...

2003-01-01

230

Gate-oxide integrity for polysilicon thin-film transistors: a comparative study for ELC, MILC and SPC crystallized active polysilicon layer  

International Nuclear Information System (INIS)

In this paper, we present the results of Plasma-Enhanced Chemical Vapor Deposition gate-oxide (SiO_2) integrity on ELC (excimer-laser-crystallized), MILC (metal-induced lateral-crystallized) and SPC (solid-phase-crystallized) polysilicon films. We observed that gate oxide strength of poly-Si TFT strongly depends on the crystallization method for the active silicon layer. In the case of ELC films, asperities on the silicon surface reduce the SiO_2 breakdown field significantly. The metallic contaminants in MILC films are responsible for a deleterious impact on gate oxide integrity. Among the three cases, the SiO_2 breakdown field was the highest for the SPC silicon films. The breakdown fields at the 50 % failure points in Weibull plots for the ELC, MILC and SPC cases were 5.1 MV/cm, 6.2 MV/cm, and 8.1 MV/cm, respectively. We conclude that the roughness and metallic contamination of the poly-Si films are the main factors that cause enhanced breakdown of SiO_2 films.

2006-01-01

231

Functional expression of anti-hepatitis B virus (HBV) preS2 antigen scFv by cspA promoter system in Escherichia coli and application as a recognition molecule for single-walled carbon nanotube (SWNT) field effect transistor (FET)  

British Library Electronic Table of Contents (United Kingdom)

The preS2 antigens of hepatitis B virus (HBV), which causes a serious health problem in the world, have been implicated in hepatocyte cell binding and viral penetration. Therefore, the importance of antibody production against preS2 antigen for early diagnosis of HBV has been well established. In this study, the recombinant HBV preS2 single chain variable fragment (scFv) antibody was successfully expressed in E. coli with the novel cold shock vector (pCold) under the cspA promoter, and its expression level was compared with the pET vector under the T7 promoter. Additionally, a host with an oxidizing cytoplasm, E. coli trxB/gor double mutant, was used to improve the soluble expression. The anti-HBV preS2 scFv using pCold vector was successfully expressed in a soluble and functional form in ...

2010-01-01

232

Full autonomous monitoring tools inside nuclear reactor building  

Energy Technology Data Exchange (ETDEWEB)

In this paper, we define, design and test a radiation tolerant autonomous monitoring tool for nuclear embedded applications. The goal of the instrumentation system was to record the values of some parameters such as dose, temperature or vibrations appearing inside the containment building of nuclear power plants. The knowledge of these parameters will be a good help for predictive maintenance of the power plant components. For the design of the monitoring tool, we rely on commercial-off-the-shelf (COTS) low power electronic components to use battery-supplied power. A large amount of components starting from discrete transistors or logic units to memories and micro-controllers was associated to define and design a prototype. We then confirm the environment conditions tolerance estimated to up to 2 kGy of total dose and 80 C for temperature by on-line irradiation experiments for individual components and functions and prototypes. Two different sets of about 60 ...

2009-07-01

233

Focused ion beam etching of nanometer-size GaN/AlGaN device structures and their optical characterization by micro-photoluminescence/Raman mapping  

Energy Technology Data Exchange (ETDEWEB)

The authors report on the nano-fabrication of GaN/AlGaN device structures using focused ion beam (FIB) etching, illustrated on a GaN/AlGaN heterostructure field effect transistor (HFET). Pillars as small as 20nm to 300nm in diameter were fabricated from the GaN/AlGaN HFET. Micro-photoluminescence and UV micro-Raman maps were recorded from the FIB-etched pattern to assess its material quality. Photoluminescence was detected from 300nm-size GaN/AlGaN HFET pillars, i.e., from the AlGaN as well as the GaN layers in the device structure, despite the induced etch damage. Properties of the GaN and the AlGaN layers in the FIB-etched areas were mapped using UV Micro-Raman spectroscopy. Damage introduced by FIB-etching was assessed. The fabricated nanometer-size GaN/AlGaN structures were found to be of good quality. The results demonstrate the potential of FIB-etching for the nano-fabrication of III-V nitride devices.

2000-07-01

234

Electrical properties of ultra-thin oxynitrided layer using N{sub 2}O plasma in inductively coupled plasma chemical vapor deposition for non-volatile memory on glass  

Energy Technology Data Exchange (ETDEWEB)

In this work, the silicon oxynitride layer was studied as a tunneling layer for non-volatile memory application by fabricating low temperature polysilicon thin film transistors on glass. Silicon wafers were oxynitrided by only nitrous oxide plasma under different radio frequency powers and plasma treatment times. Plasma oxynitridation was performed in RF plasma using inductively coupled plasma chemical vapor deposition. The X-ray energy dispersive spectroscopy was employed to analyze the atomic concentration ratio of nitrogen/oxygen in oxynitride layer. The oxynitrided layer formed under radio frequency power of 150 W and substrate temperature of 623 K was found to contain the atomic concentration ratio of nitrogen/oxygen as high as 1.57. The advantage of high nitrogen concentration in silicon oxide layer formed by using nitrous oxide plasma was investigated by capacitance-voltage measurement. The analysis of capacitance-voltage characteristics demonstrated that ...

2007-06-04

235

Electrical properties of ultra-thin oxynitrided layer using N_2O plasma in inductively coupled plasma chemical vapor deposition for non-volatile memory on glass  

International Nuclear Information System (INIS)

In this work, the silicon oxynitride layer was studied as a tunneling layer for non-volatile memory application by fabricating low temperature polysilicon thin film transistors on glass. Silicon wafers were oxynitrided by only nitrous oxide plasma under different radio frequency powers and plasma treatment times. Plasma oxynitridation was performed in RF plasma using inductively coupled plasma chemical vapor deposition. The X-ray energy dispersive spectroscopy was employed to analyze the atomic concentration ratio of nitrogen/oxygen in oxynitride layer. The oxynitrided layer formed under radio frequency power of 150 W and substrate temperature of 623 K was found to contain the atomic concentration ratio of nitrogen/oxygen as high as 1.57. The advantage of high nitrogen concentration in silicon oxide layer formed by using nitrous oxide plasma was investigated by capacitance-voltage measurement. The analysis of capacitance-voltage characteristics demonstrated that ...

2007-06-04

236

Electrical characteristics of AlxGa1-xN Schottky diodes prepared by a two-step surface treatment  

Science.gov (United States)

Near-ideal Schottky barrier contacts to n-type Al0.22Ga0.78N have been developed by a two-step surface treatment technique. Plasma etching of the AlxGa1-xN surface prior to Schottky metal deposition, combined with sequential chemical treatment of the etched surface, holds promise for developing high quality low-leakage Schottky contacts for low noise applications and for recessed gate high electron mobility transistors. In this work, the effect of postetch chemical treatment of the n-type Al0.22Ga0.78N surface on the performance of the Ni/Au based Schottky contact has been investigated. Three different types of chemical treatment: viz, reactive ion etching, reactive ion etching plus dipping in hot aqua regia, and reactive ion etching plus dipping in hot KOH, are studied. Detailed current-voltage studies of three different surface treated diodes and a comparison with as-deposited diodes reveal significant improvement in the diode characteristics. The latter surface ...

2004-09-01

237

A plasma process for the synthesis of cubic-shaped silicon nanocrystals for nanoelectronic devices  

International Nuclear Information System (INIS)

Low pressure silane plasmas are known for their ability to synthesize silicon nanoparticles via gas phase nucleation. While in the past this particle formation has often been considered from the viewpoint of a contamination problem in semiconductor processing, we here describe a silane low pressure plasma that enables the synthesis of highly oriented, cubic-shaped silicon nanocrystals with a rather monodisperse size distribution. These silicon nanocubes have successfully been used in the manufacture of single nanoparticle vertical transistors. We discuss the advantages of this new paradigm of building nanoelectronic devices. The plasma synthesis process is characterized in more detail than in prior work. The particle nucleation, growth and shape evolution are studied. Results indicate that the process provides two spatially distinct zones: a diffuse plasma for particle growth and a constricted plasma zone for particle annealing. Measurements of the plasma ion ...

2007-04-21

238

Luminescent unit computerization to research spectral characteristics of fine film alkali halide crystal  

International Nuclear Information System (INIS)

The fundamental optical absorption of ion crystals characterizes the creation of different free low energetic electronic excitation (the excitons and electron-hole pairs), but their straight registration is not possible because of incommensurable big absorption factor of alkali halide monocrystals. So to registration the spectrums of alkali halide monocrystal very fine layers are necessary. We have received fine films of Nal and KCl in system of KCl-Nal-KCl, KCl-KI-KCl on the base of universal vacuum post VUP-4, VUP-5 by thermal evaporation. A unique spectral unit has been created For this on the basic the SDL-2 complex. Complex consists of radiator, systems of condensers, monochromators MDR-12 and MDR-23, receivers of radiation, controller by unit. Connect and control of monochromators by means of IBM-compatible computer has been created. Kinematics schemes of monochromators provide consequent removing on output slot of monochromatic radiation in operating range of each diffraction ...

239

Report of National Cancer Institute symposium: comparison of mechanisms of carcinogenesis by radiation and chemical agents. I. Common molecular mechanisms  

Science.gov (United States)

Some aspects of molecular mechanisms common to radiation and chemical carcinogenesis are discussed, particularly the DNA damage done by these agents. Emphasis is placed on epidemiological considerations and on dose-response models used in risk assessment to extrapolate from experimental data obtained at high doses to the effects from long-term, low-level exposures. 3 references, 6 figures. (ACR)

1984-01-01

240

Quantum mechanical interpretation for the role of polyamines in acid corrosion inhibition  

International Nuclear Information System (INIS)

The inhibitor action of unbranched polyamines on corrosion of low-carbon steel in 0.5 M sulfuric acid is studied through potentiostatic polarization curves. It is shown that the inhibitor efficiency I depends on the polyamine concentration and molecular structure. The quantum-mechanical calculations of molecular properties are accomplished through the MNDO method. Correlation between the measured I and physicochemical properties of the polyamine inhibitors in protonized and nonprotonized form is found with application of the general perturbation theory

241

Pharmaceutics | Special Issue: Molecular Imaging  

Wastenet

...) Abstract: Fluorescence microscopic imaging is widely used in biomedical research to study molecular and cellular processes in cell culture or tissue samples. This is motivated by the high inherent sensitivity of fluorescence techniques, the spatial resolution that compares favorably with cellular dimensions, the stability of the fluorescent labels used and the sophisticated strategies that have been developed for selectively labeling target molecules. More recently, two and ...

242

Molecular recognition of nitrated fatty acids by PPAR[gamma  

Energy Technology Data Exchange (ETDEWEB)

Peroxisome proliferator activated receptor-{gamma} (PPAR{gamma}) regulates metabolic homeostasis and adipocyte differentiation, and it is activated by oxidized and nitrated fatty acids. Here we report the crystal structure of the PPAR{gamma} ligand binding domain bound to nitrated linoleic acid, a potent endogenous ligand of PPAR{gamma}. Structural and functional studies of receptor-ligand interactions reveal the molecular basis of PPAR{gamma} discrimination of various naturally occurring fatty acid derivatives.

2010-03-08

243

Molecular model for de Vries type smectic A - smectic C phase transition in liquid crystals  

CERN Document Server

We develop a theory of Smectic A - Smectic C phase transition with anomalously weak smectic layer contraction. We construct a phenomenological description of this transition by generalizing the Chen-Lubensky model. Using a mean-field molecular model, we demonstrate that a relatively simple interaction potential suffices to describe the transition. The theoretical results are in excellent agreement with experimental data.

2007-01-01

244

Molecular methods  

Energy Technology Data Exchange (ETDEWEB)

Chapter 5, describes some of the most important molecular methods used in the study of chromosome structure and function. The methods discussed include fragmentation of DNA, cloning, flow cytometry and chromosome sorting, is situ hybridization, polymerase chain reaction (PCR), and yeast artificial chromosomes (YACs). 18 refs., 3 figs., 1 tab.

1993-12-31

245

Molecular dynamics simulation of nanoctrystalline nickel: structure and mechanical properties  

Energy Technology Data Exchange (ETDEWEB)

Molecular dynamics computer simulations of a dense nanocrystalline Nickel sample are performed on the parallel Cray T3 (EPFL-Lausanne). The sample contains 50 grains with an average size of 3 nm. By perturbing the relaxed configuration elastic and plastic properties are studied. (author) 1 fig., 1 ref.

1996-10-01

246

Metalloporphyrin catalysts for oxygen reduction developed using computer-aided molecular design  

Energy Technology Data Exchange (ETDEWEB)

The objective of this project is the development of a new class of metalloporphyrin materials used as catalsyts for use in fuel cell applications. The metalloporphyrins are excellent candidates for use as catalysts at both the anode and cathode. The catalysts reduce oxygen in 1 M potassium hydroxide, as well as in 2 M sulfuric acid. Covalent attachment to carbon supports is being investigated. The computer-aided molecular design is an iterative process, in which experimental results feed back into the design of future catalysts.

1996-04-01

247

Metal nanoparticle inks  

Energy Technology Data Exchange (ETDEWEB)

Stabilized silver particles comprise particles comprising silver, a short-chain capping agent adsorbed on the particles, and a long-chain capping agent adsorbed on the particles. The short-chain capping agent is a first anionic polyelectrolyte having a molecular weight (Mw) of at most 10,000, and the long-chain capping agent is a second anionic polyelectrolyte having a molecular weight (Mw) of at least 25,000. The stabilized silver particles have a solid loading of metallic silver of at least 50 wt %.

2011-04-12

248

Catalytic chemistry  

Energy Technology Data Exchange (ETDEWEB)

Most chemical reactions in industry and biology are catalytic and play a role at some stage of the processing of about 80% of the goods manufactured in the U.S., yet catalysis is a neglected subject in chemical education. This book integrates the fragmentary treatment accorded the topic until now. It covers, in a unified way, catalysis in solutions, by enzymes, in synthetic polymers within the molecular scale cages of zeolites and other molecular sieves, and on surfaces of inorganic solids. The central ideas are chemical; and principles are illustrated by emphasizing industrial reactions and catalysts.

1991-01-01

249

Ab initio molecular dynamics with born-oppenheimer and extended lagrangian methods using atom centered basis functions  

Energy Technology Data Exchange (ETDEWEB)

In ab initio molecular dynamics, whenever information about the potential energy surface is needed for integrating the equations of motion, it is computed 'on the fly' using electronic structure calculations. For Born-Oppenheimer methods, the electronic structure calculations are converged, whereas in the extended Lagrangian approach the electronic structure is propagated along with the nuclei. Some recent advances for both approaches are discussed.

2003-06-01

250

2004 Reversible Associations in Structure & Molecular Biology  

Energy Technology Data Exchange (ETDEWEB)

The Gordon Research Conference (GRC) on 2004 Gordon Research Conference on Reversible Associations in Structure & Molecular Biology was held at Four Points Sheraton, CA, 1/25-30/2004. The Conference was well attended with 82 participants (attendees list attached). The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both U.S. and foreign scientists, senior researchers, young investigators, and students.

2005-03-23

251

The Distribution and Condition of the Warm Molecular Gas in Abell 2597 and Sersic 159-03  

CERN Document Server

We have used the SINFONI integral field spectrograph to map the near-infrared K-band emission lines of molecular and ionised hydrogen in the central regions of two cool core galaxy clusters, Abell 2597 and Sersic 159-03. Gas is detected out to 20 kpc from the nuclei of the brightest cluster galaxies and found to be distributed in clumps and filaments around it. The ionised and molecular gas phases trace each other closely in extent and dynamical state. Both gas phases show signs of interaction with the active nucleus. Within the nuclear regions the kinetic luminosity of this gas is found to be somewhat smaller than the current radio luminosity. Outside the nuclear region the gas has a low velocity dispersion and shows smooth velocity gradients. There is no strong correlation between the intensity of the molecular and ionised gas emission and either the radio or X-ray emission. The molecular gas in Abell ...

2010-01-01

252

Maintenance and regulation of extracellular volume and the ion environment in Drosophila larval nerves.  

Science.gov (United States)

In mammals and insects, paracellular blood barriers isolate the nervous system from the rest of the animal. Glia and accessory cells of the nervous system use pumps, channels, cotransporters, and exchangers collectively to maintain the extracellular ion environment and osmotic balance in the nervous system. At present, the molecular mechanisms that regulate this process remain unclear. In humans, loss of extracellular ion and volume regulation in the nervous system poses serious health threats. Drosophila is a model genetic organism with a proven track record for uncovering molecular mechanisms relevant to human health and disease. Here, we review what is known about extracellular ion and volume regulation in larval abdominal nerves, present some new data about the impact of neural activity on the extracellular environment, and relate the findings to mammalian systems. Homologies have been found at the level of morphology, physiology, ...

2011-02-08

253

Some properties of explosive mixtures containing peroxides  

International Nuclear Information System (INIS)

This study concerns mixtures of triacetone triperoxide (3,3,6,6,9,9-hexamethyl-1,2,4,5,7,8-hexoxonane, TATP) and ammonium nitrate (AN) with added water (W), as the case may be, and dry mixtures of TATP with urea nitrate (UN). Relative performances (RP) of the mixtures and their individual components, relative to TNT, were determined by means of ballistic mortar. The detonation energies, E_0, and detonation velocities, D, were calculated for the mixtures studied by means of the thermodynamic code CHEETAH. Relationships have been found and are discussed between the RP and the E_0 values related to unit volume of gaseous products of detonation of these mixtures. These relationships together with those between RP and oxygen balance values of the mixtures studied indicate different types of participation of AN and UN in the explosive decomposition of the respective mixtures. Dry TATP/UN mixtures exhibit lower RP than analogous mixtures TATP/AN containing up to 25% of ...

2008-06-15

254

Shape evolution of nanostructures by thermal and ion beam processing. Modeling and atomistic simulations  

International Nuclear Information System (INIS)

Single-crystalline nanostructures often exhibit gradients of surface (and/or interface) curvature that emerge from fabrication and growth processes or from thermal fluctuations. Thus, the system-inherent capillary force can initiate morphological transformations during further processing steps or during operation at elevated temperature. Therefore and because of the ongoing miniaturization of functional structures which causes a general rise in surface-to-volume ratios, solid-state capillary phenomena will become increasingly important: On the one hand diffusion-mediated capillary processes can be of practical use in view of non-conventional nanostructure fabrication methods based on self-organization mechanisms, on the other hand they can destroy the integrity of nanostructures which can go along with the failure of functionality. Additionally, capillarity-induced shape transformations are effected and can thereby be controlled by applied fields and forces (guided or driven ...

2009-05-12

255

Dynamics of a very intense pulsed electron beam  

Energy Technology Data Exchange (ETDEWEB)

A unique beam of pulsed electrons has been developed using the 19-MeV, 700-kA Hermes-III accelerator. The extended planar-anode diode is used to extract at large radius an annular electron beam from the accelerator and inject the resulting beam at small angle into a low-pressure gas cell, where the beam is rapidly charge neutralized and almost current neutralized. Under these conditions, the beam propagates nearly ballistically to a focus downstream of injection, where objects can be placed for irradiation and study. For a focal length of 78 cm, measurements with a segmented calorimeter show that this configuration can deliver an energy deposition of 200 J/g [20 Mrad] over a useful area of 70 cm{sup 2} and a 4-cm depth in graphite in 25 ns. Increasing the injection angle by reducing the AK gap permits higher doses over smaller areas to be achieved. Such beams are of interest for the study of material property changes from short-pulse high-energy depositions and for ...

1994-12-31

256

Molecular orbitals of nucleons in nucleus-nucleus collisions  

International Nuclear Information System (INIS)

A formalism for the dynamical treatment of the molecular orbitals of valence nucleons in nucleus-nucleus collisions is developed with the use of the coupled-reaction-channel (CRC) method. The Coriolis coupling effects as well as the finite mass effects of the nucleon are taken into account in this model, of rotating molecular orbitals, RMO. First, the validity of the concept is examined from the viewpoint of the multi-step processes in a standard CRC calculation for systems containing two identical [core] nuclei. The calculations show strong CRC effects particularly in the case where the mixing of different l-parity orbitals - called hybridization in atomic physics - occurs. Then, the RMO representation for active nucleons is applied to the same systems and compared to the CRC results. Its validity is investigated with respect to the radial motion (adiabaticity) and the rotation of the molecular axis (radial and rotational ...

257

Synthesis, Herbicidal Activities and Comparative Molecular Field Analysis Study of Some Novel Triazolinone Derivatives  

British Library Electronic Table of Contents (United Kingdom)

A series of novel triazolinones were synthesized and their structures were characterized by 1H NMR, elemental analysis and single-crystal X-ray diffraction analysis. The herbicidal activities were evaluated against Echinochloa crusgalli (L.) Beauv., Digitaria adscendens, Brassica napus and Amaranthus retroflexus. The herbicidal activity data indicated that the title compounds had higher activities with substituted benzyl group moieties than with other groups such as sulfonyl, alkyl, etc. To further investigate the structure-activity relationship, comparative molecular field analysis was performed on the basis of herbicidal activity data. Both the steric and electronic field distributions of comparative molecular field analysis are in good agreement in this work. The results showed that a b...

2009-01-01

258

Suitability of Molecular Markers for Selection of Potatoes Resistant to Globodera spp  

British Library Electronic Table of Contents (United Kingdom)

Globodera rostochiensis and Globodera pallida are parasitic root cyst nematodes of potato (PCN), which significantly reduce yield and quality. The genetics and available molecular markers should make resistance to nematodes an excellent candidate for marker assisted selection. The study presents results of testing the suitability of known molecular markers for detection of resistance in a set of cultivars. We revealed some inconsistencies in genealogical data of the cultivars and showed inconsistent usefulness in detecting resistant cultivars. The marker TG689 was identified in almost all cultivars resistant to G. rostochiensis and together with other markers was used for verifying the resistance in a group of breeding lines. The marker TG689 was the most effective. However, the efficiency...

2011-01-01

259

Shale oil value enhancement research. Quarterly report, October 1, 1993--December 31, 1993  

Energy Technology Data Exchange (ETDEWEB)

The first year of this effort was focussed on the following broad objectives: (1) Analyze the molecular types present in shale oil (as a function of molecular weight distribution); (2) Determine the behavior of these molecular types in liquid-liquid extraction; (3) Develop the analytical tools needed to systematize the process development; (4) Survey the markets to assure that these have high value uses for the types found in shale oil; (5) Explore selective process means for extracting/converting shale oil components into concentrates of potentially marketable components; (6) Compile overview of the venture development strategy and begin implementation of that strategy. Each of these tasks has been completed in sufficient detail that we can now focus on filling in the knowledge gaps evident from the overview.

1997-05-01

260

Pursuing laplace`s vision on modern computers  

Energy Technology Data Exchange (ETDEWEB)

This contribution is an informal essay based on a talk delivered at the Institute for Mathematics and its Applications (IMA) in Minneapolis, under the summer program in molecular biology, July 18-22, 1994. I exclude many technical details, which can be found elsewhere, and instead focus on the basic ideas of molecular dynamics simulations, with the goal of conveying to students and non-specialists the key concepts of the theory and practice of large-scale simulations. Following a description of the basic idea in molecular dynamics, I discuss some of the practical details involved in simulations of large biological molecules, the numerical timestep problem, and approaches to this problem based on implicit-integration techniques. I end with a perspective of open challenges in the field and directions for future research. 79 refs., 6 figs., 1 tab.

1996-12-31

261

Predicting the proton conductivity of perfluorosulfonic acid membrane via combining statistical thermodynamics and molecular dynamics simulation  

British Library Electronic Table of Contents (United Kingdom)

Abstract The electrochemical properties of a perfluorosulfonic acid (PFSA) membrane are estimated using a combination of molecular dynamics simulation and statistical thermodynamic model. We obtain all parameters in an ionic conductivity model from an atomistic simulation and remove all adjusted model parameters. From a microscopic point of view, the hydrated PFSA membrane shows micro-phase segregation which separated into hydrophilic and hydrophobic phases. Our present work originates with this phenomenon and we treat this phase segregation as if it is a continuous phase for each of which the proton (H+) is transported inside the PFSA membrane/solvent (water and alcohols) mixture. The chemical potential for a given system is estimated using a molecular simulation technique to predict the ...

2011-01-01

262

Monolayers at air-water interfaces: from origins-of-life to nanotechnology  

British Library Electronic Table of Contents (United Kingdom)

Abstract The air-water interface presents several interesting features, namely a) a molecularly flat environment, b) a boundary region between two phases with different dielectric constants, c) permits or promotes dynamic interactions within the interface region, and d) a point of interaction between hydrophobic compounds and aqueous molecules. Accordingly, Langmuir monolayers at the air-water interface have several unique characteristics and properties, which require investigation. In this review-type personal account, typical examples of molecular recognition and molecular patterning at air-water interfaces are first introduced, followed by descriptions of specific and unusual properties of monolayers on water. In addition, two examples of our own results concerning Langmuir monolayers a...

2011-01-01

263

Molecular biology of the renin-angiotensin system  

Energy Technology Data Exchange (ETDEWEB)

This paper reviews the molecular biology of the renin-angiotensin system. The renin gene structure is analyzed in detail, including an examination of the putative regulatory regions. The combined action of these regulatory sequences would result in the complex, tissue-specific expression and regulation observed in vivo. The expression of the tissue renin-angiotensin systems, which may have important physiological functions, is also described. In addition, the pathway of renin biosynthesis and secretion is reviewed. This includes speculation on the fate of circulating prorenin and the physiological role of multiple renin forms and secretory pathways. The molecular approaches described in this paper have greatly advanced our knowledge of the biology of the renin-angiotensin system. Future studies using these and other approaches should provide further insight into this complex system.

1988-10-01

264

Modelling the tribology of thin film interfaces  

CERN Document Server

substrate). Within each group of simulations, three lubricant film thicknesses are studied to examine the effect of varying lubricant thickness. Statistical data are collected from each simulation and presented in this work. Via these data, together with the evolution, of atomic and molecular configurations, a very detailed picture of the properties of this thin film interface is presented. In particular, we conclude that perfluoropolyether lubricant forms distinct molecular layers when confined between two substrates, the rate of heat generation under shearing conditions typical of those in a head-disk interface is insufficient for thermal mechanisms to result directly in lubricant degradation, and mechanical stresses attained in the head-disk interface are unlikely to result in any significant degree of lubricant degradation. This thesis examines the tribology of a head-disk interface in an operating hard disk drive via non-equilibrium ...

2000-01-01

265

Metal work function tuning with new molecular acceptors  

Energy Technology Data Exchange (ETDEWEB)

The interfaces between metal electrodes and electroactive organic materials are important for the performance of organic electronic devices. One way of optimizing the anode/organic interface is the insertion of a (sub-)monolayer of molecular acceptors. Here we present an UPS study of new electron acceptor molecules deposited on Au(111), Cu(111) and Ag(111). This study intends to improve the understanding of how the interactions of specific electron withdrawing groups with metal surfaces are correlated with observed modifications of interfacial electron density distribution, work function change ({delta}{phi}), and the energy level alignment. We find that {delta}{phi}, which is the difference between the work function ({phi}) of the clean metal surface and {phi} after formation of a molecular monolayer, is a monotonic function of initial {phi} of the metal. Two different slopes were observed for acceptors with cyano and those with keto or nitro ...

2008-07-01

266

Low-temperature oxidative degradation of PBX 9501 and its components determined via molecular weight analysis of the Poly[ester urethane] binder  

British Library Electronic Table of Contents (United Kingdom)

The results of following the oxidative degradation of a plastic-bonded explosive (PBX 9501) are reported. Into over 1100 sealed containers were placed samples of PBX 9501 and combinations of its components and aged at relatively low temperatures to induce oxidative degradation of the samples. One of the components of the explosive is a poly(ester urethane) polymer and the oxidative degradation of the samples were following by measuring the molecular weight change of the polymer by gel permeation chromatography (coupled with both differential refractive index and multiangle laser light scattering detectors). Multiple temperatures between 40 and 64 degreeC were used to accelerate the aging of the samples. Interesting induction period behavior, along with both molecular weight increasing (cro...

2009-01-01

267

Fermionic molecular dynamics for ground states and collisions of nuclei  

International Nuclear Information System (INIS)

The antisymmetric many-body trial state which describes a system of interacting fermions is parametrized in terms of localized wave packets. The equations of motion are derived from the time-dependent quantum variational principle. The resulting fermionic molecular dynamics (FMD) equations include a wide range of semi-quantal to classical physics extending from deformed Hartree-Fock theory to newtonian molecular dynamics. Conservation laws are discussed in connection with the choice of the trial state. The model is applied to heavy-ion collisions with which its basic features are illustrated. The results show a great variety of phenomena including deeply inelastic collisions, fusion, incomplete fusion, fragmentation, neck emission, promptly emitted nucleons and evaporation. ((orig.)).

268

Direct observation of polymerization in the oleic acid-ozone heterogeneous reaction system by photoelectron resonance capture ionization aerosol mass spectrometry  

British Library Electronic Table of Contents (United Kingdom)

High molecular weight products of the ozonolysis reaction of particle-phase 9-octadecenoic acid (oleic acid) have been studied by photoelectron resonance capture ionization (PERCI) mass spectrometry (MS). Oleic acid particles ( Formula Not Shown , Formula Not Shown ) were reacted with ozone (1.8x10-4atm) in a flow reactor at reaction times of 8 and 23s. Particles were sampled on-line with a differentially pumped particle inlet and chemically analyzed by PERCI-MS. PERCI is a soft ionization method that permits the direct measurement of relatively high molecular weight compounds, facilitating molecular identification. In addition to cyclic oxygenates, such as secondary ozonides and geminal diperoxides that were reported previously, we demonstrate the formation of polymers at the particle sur...

2006-01-01

269

Chemistry of dense clumps near moving Herbig-Haro objects  

British Library Electronic Table of Contents (United Kingdom)

Abstract Localized regions of enhanced emission from HCO+, NH3 and other species near Herbig-Haro objects (HHOs) have been interpreted as arising in a photochemistry stimulated by the HHO radiation on high-density quiescent clumps in molecular clouds. Static models of this process have been successful in accounting for the variety of molecular species arising ahead of the jet; however, recent observations show that the enhanced molecular emission is widespread along the jet as well as ahead. Hence, a realistic model must take into account the movement of the radiation field past the clump. It was previously unclear as to whether the short interaction time between the clump and the HHO in a moving source model would allow molecules such as HCO+ to reach high enough levels, and to survive fo...

2011-01-01

270

An experimental and molecular-statistical study of the adsorption of the iodobenzene, 2-iodothiophene, and isomeric iodoadamantane molecules on the graphite basal face surface  

Science.gov (United States)

The thermodynamic characteristics of adsorption of iodobenzene, 2-iodothiophene, and 1- and 2-iodoadamantanes on the surface of graphitized thermal carbon black were determined experimentally. The influence of the special features of the molecular structure of the adsorbates on the thermodynamic characteristics of adsorption was studied. The atom-atom approximation of the semiempirical molecular-statistical theory of adsorption was used to calculate the thermodynamic characteristics of adsorption of the adsorbates using the newly determined potential function parameters of pair intermolecular interaction (?( r)) of I with C atoms of the basal graphite face. For the example of isostructural monohalogenated benzenes, thiophenes, and adamantanes, a comparative analysis of the contributions of the F, Cl, Br, and I atoms to the thermodynamic characteristics of adsorption was performed for the nonspecific adsorption of these compounds on a plane ...

2011-04-01

271

All-atom molecular dynamics simulations using orientational constraints from anisotropic NMR samples  

British Library Electronic Table of Contents (United Kingdom)

Orientational constraints obtained from solid state NMR experiments on anisotropic samples are used here in molecular dynamics (MD) simulations for determining the structure and dynamics of several different membrane-bound molecules. The new MD technique is based on the inclusion of orientation dependent pseudo-forces in the COSMOS-NMR force field. These forces drive molecular rotations and re-orientations in the simulation, such that the motional time-averages of the tensorial NMR properties approach the experimentally measured parameters. The orientational-constraint-driven MD simulations are universally applicable to all NMR interaction tensors, such as chemical shifts, dipolar couplings and quadrupolar interactions. The strategy does not depend on the initial choice of coordinates, and...

2007-01-01

272

Adsorption and Dissociation of Molecular Hydrogen on the (0001) Surface of DHCP Americium  

Science.gov (United States)

Hydrogen molecule adsorption on the (0001) surface of double hexagonal closed packed americium has been studied in detail within the framework of density functional theory. Weak molecular hydrogen adsorptions were observed. The most stable configuration corresponded to a Hor2 approach molecular adsorption at the one-fold top site where the molecule's approach is perpendicular to a lattice vector. Adsorption energies and adsorption geometries for different adsorption sites will be discussed. The change in work functions, magnetic moments, partial charges inside muffin-tins, difference charge density distributions and density of states for the bare Am slab and the Am slab after adsorption of the hydrogen molecule will be discussed. Reaction barrier for the dissociation of hydrogen molecule will be presented. The implications of adsorption on Am 5f electron localization-delocalization will be summarized.

2009-03-01

273

Accelerated aging speeds test of instrument reliability  

International Nuclear Information System (INIS)

This paper shows how molecular theory paves the way for accelerated aging tests of safety-related equipment in nuclear power plants, as required by NRC qualification programs. Arrhenius' model, based on an equation, provides useful information regarding the extent of molecular change as a function of time and temperature. Critical to determining the aging characteristics and qualified life of organic materials is the activation energy concept, which is derived from information gathered when the molecular reaction of the material is documented over the entire life cycle. In accelerated-aging applications, the importance of the model lies in characterizing the chemical related reactions of materials. The problem with the Arrhenius approach is that, in generating a testing period of reasonable duration, a rather high test temperature must be selected which may lead to an added and unrelated environmental effect.

1982-01-01

274

[Malignant transformation of human fibroblasts by neutrons and by gamma radiation: Relationship to mutations induced  

Energy Technology Data Exchange (ETDEWEB)

A brief overview if provided of selected reports presented at the International Symposium on Molecular Mechanisms of Radiation- and Chemical Carcinogen-Induced Cell Transformation held at Mackinac Island, Michigan on September 19-23, 1993.

1993-12-31

275

X rays in molecular biophysics  

Energy Technology Data Exchange (ETDEWEB)

An atom-by-atom understanding of life processes is emerging from a flurry of experiments fueled by synchrotron sources and DNA technology. {copyright} 1995 {ital American} {ital Institute} {ital of} {ital Physics}.

1995-11-01

276

Voluntary exercise improves insulin sensitivity and adipose tissue inflammation in diet-induced obese mice  

UK PubMed Central (United Kingdom)

Exercise promotes weight loss and improves insulin sensitivity. However, the molecular mechanisms mediating its beneficial effects are not fully understood. Obesity correlates with increased production...Full Text Available

2008-09-01

277

Upgrading low molecular weight hydrocarbons  

Energy Technology Data Exchange (ETDEWEB)

This patent describes a process for the conversion of low molecular weight alkanes to higher molecular weight hydrocarbons. It comprises: contacting the low molecular weight alkanes, at an elevated temperature, with oxygen and a catalyst of the formula Zn{sub a}A{sub b}M{sub c}M'{sub d}O{sub x} wherein A is Li, Na, K, or mixtures thereof; M is Al, Ga, Cr, La, Y, Sc, V, Nb, Ta, Cu or mixtures thereof; M' is Cs, Rb, Mg, Ca, Sr, Ba, Sm, Pb, Mn, Sb, P, Sn, Bi, Ti, Zr, Hf, or mixtures thereof; a if from about 1 to about 20; b is from about 0.1 to about 20; c is from about 0 to about 5 d is from about 0 to about 20, and x is a number needed to fulfill the valence requirements of the other elements; provided that at least one c and d is a t least 0.1; and when M' is Sn, c must be at least 0.1.

1989-12-12

278

Twist-1 is a PPAR ?-inducible, negative feedback regulator of PGC-1 ? in brown fat metabolism  

UK PubMed Central (United Kingdom)

SummaryBrown fat is specialized in energy expenditure, a process that is principally controlled by the transcriptional co-activator PGC-1α. Here we describe a molecular...Full Text Available

2009-04-03

279

The pharmacology and molecular mechanisms underlying temperature regulation and torpor  

UK PubMed Central (United Kingdom)

The ability to enter a hypometabolic state upon restriction of caloric intake is pivotal for animal survival: balancing the energy budget in endotherms can be a real struggle when food is not...Full Text Available

2008-10-01

280

The molecular lesion in the alpha-N-acetylgalactosaminidase gene that causes angiokeratoma corporis diffusum with glycopeptiduria.  

UK PubMed Central (United Kingdom)

Angiokeratoma corporis diffusum with glycopeptiduria is a recently recognized inborn error of glycoprotein catabolism resulting from the deficient activity of human alpha-N-acetylgalactosaminidase (E.C....Full Text Available

1994-08-01

281

The immunohistochemistry of invasive and proliferative phenotype switching in melanoma: a case report  

UK PubMed Central (United Kingdom)

PurposeTo date there remains no effective therapy for metastatic melanoma and at the molecular level disease progression remains poorly understood. Recent work by...Full Text Available

2010-08-01

282

The hemoglobins of the trematodes Fasciola hepatica and Paramphistomum epiclitum: A molecular biological, physico-chemical, kinetic, and vaccination study  

UK PubMed Central (United Kingdom)

The trematode Fasciola hepatica (Fa.he.) is a common parasite of human and livestock. The hemoglobin (Hb) of Fa.he., a potential immunogen, was chosen for characterization...Full Text Available

2008-10-01

283

The erratic mitochondrial clock: variations of mutation rate, not population size, affect mtDNA diversity across birds and mammals  

UK PubMed Central (United Kingdom)

BackgroundDuring the last ten years, major advances have been made in characterizing and understanding the evolution of mitochondrial DNA, the most popular marker of molecular biodiversity....Full Text Available

284

The Dynamical Mechanism of Auto-Inhibition of AMP-Activated Protein Kinase  

UK PubMed Central (United Kingdom)

We use a novel normal mode analysis of an elastic network model drawn from configurations generated during microsecond all-atom molecular dynamics simulations to analyze the mechanism of auto-inhibition...Full Text Available

2011-07-01

285

The Biochemical and Molecular Basis for the Divergent Patterns in the Biosynthesis of Terpenes and Phenylpropenes in the Peltate Glands of Three Cultivars of Basil1  

UK PubMed Central (United Kingdom)

Surface glandular trichomes distributed throughout the aerial parts of sweet basil (Ocimum basilicum) produce and store monoterpene, sesquiterpene, and phenylpropene volatiles. Three...Full Text Available

2004-11-01

286

Technical and clinical assessment of oxygen concentrators.  

UK PubMed Central (United Kingdom)

One membrane oxygen enricher (Oxygen Enrichment Company OE-4E) and four molecular sieve (MS) concentrators (Mountain Medical Econo2, De Vilbiss MINI DeVO2, Cryogenic Roomate III, and Mountain Medical...Full Text Available

1985-11-01

287

Synchrotron PES and NEXAFS studies of self-assembled aromatic thiol monolayers on Au(1 1 1)  

Energy Technology Data Exchange (ETDEWEB)

Self-assembled monolayers (SAMs) on various metal, semiconductor or insulator substrates can be easily modified with specific functional groups of interest and have promising applications in surface wetting (hydrophobic/hydrophilic modification), tribology, corrosion protection, sensor electrodes modification, molecular and biomolecular recognition, protein adsorption, cell adhesion, and molecular- or organic-electronic device fabrications. In this paper, we highlight recent progress in the development of SAMs on solid substrates as well as their practical applications, with particular emphasis on the characterization of self-assembled aromatic thiol monolayers with different functional groups on Au(1 1 1) using synchrotron-based photoemission spectroscopy and near-edge X-ray absorption fine structure measurements. The SAM-related molecular orientation, electronic structures, and chemical bonding are presented. Using ...

2009-05-15

288

Study on the variations of molecular structures of some biomolecules induced by free electron laser using FTIR spectroscopy  

International Nuclear Information System (INIS)

In this study, free electron laser (FEL) with selective wavelength was used to induce structure changes of biomolecules, which were characterized by FTIR spectroscopy. For understanding of the interactions between FEL and biomolecules as well as biological tissues, the biomolecules investigated are ATP, ADP, AMP, t-RNA, D-ribose and the complex of SmCl_3-D-ribose. Their FTIR spectra before and after irradiation of FEL show molecular structure variations of the samples after irradiation of FEL, especially the rearrangement of their hydrogen bond networks. Along with the various irradiation wavelengths, irradiation time and molecular structures, the changes after irradiation are different for these molecules. In the FTIR spectra after irradiation, the phenomenon that the bands split into several peaks indicates the existence of several structures, conformations and configurations, which may be prompted by multiple photons process induced by FEL. ...

2007-05-01

289

Stressed-Induced TMEM135 Protein Is Part of a Conserved Genetic Network Involved in Fat Storage and Longevity Regulation in Caenorhabditis elegans  

UK PubMed Central (United Kingdom)

Disorders of mitochondrial fat metabolism lead to sudden death in infants and children. Although survival is possible, the underlying molecular mechanisms which enable this outcome have not yet been...Full Text Available

290

Stress Resistance and Longevity Are Not Directly Linked to Levels of Enzymatic Antioxidants in the Ponerine Ant Harpegnathos saltator  

UK PubMed Central (United Kingdom)

BackgroundThe molecular mechanisms of variations in individual longevity are not well understood, even though longevity can be increased substantially by means of diverse experimental...Full Text Available

291

Statistical treatment of the inner M-shell excitation in heavy ion-atom collisions  

Energy Technology Data Exchange (ETDEWEB)

A statistical treatment has been applied to interpret the experimental data on the Xe M-shell vacancy production in slow 1.05 MeV Xe-Xe collisions and is shown to give better agreement with experiment than that of the molecular-orbital models.

1983-06-27

292

Spindle cell carcinoma of head and neck: an immunohistochemical and molecular approach to its pathogenesis  

UK PubMed Central (United Kingdom)

BackgroundSpindle cell carcinoma (SpCC) is a rare microscopic type of cancer of the mouth and oropharynx. Although SpCC is thought to arise from squamous cell carcinoma (SCC), it...Full Text Available

2007-05-01

293

Some properties of beta-toxin produced by Clostridium perfringens type C.  

UK PubMed Central (United Kingdom)

Purified beta-toxin from Clostridium perfringens type C was found to be a single polypeptide chain protein with a molecular weight of approximately 30,000. The toxin was heat labile, with 75% of its...Full Text Available

1978-08-01

294

Solution structure of two molecular motor domains: nonclaret disjunctional and kinesin.  

UK PubMed Central (United Kingdom)

The effects of selected ligands on the structure of the truncated heavy-chain chemomechanical motor domains of Drosophila ncd and human kinesin were compared using the technique of transient electric...Full Text Available

1995-04-01

295

Site-specific modification of albumin by free radicals. Reaction with copper(II) and ascorbate.  

UK PubMed Central (United Kingdom)

Exposure of albumin to Cu(II) (10-100 microM) and ascorbate (0.1-2 mM) results in extensive molecular modifications, indicated by decreased fluorescence and chain breaks. The rate of utilization of...Full Text Available

1986-06-01

296

Selective imaging of adherent targeted ultrasound contrast agents  

UK PubMed Central (United Kingdom)

The goal of ultrasonic molecular imaging is the detection of targeted contrast agents bound to receptors on endothelial cells. We propose imaging methods that can distinguish adherent microbubbles...Full Text Available

2007-04-21

297

Seizures increase cell proliferation in the dentate gyrus by shortening progenitor cell cycle length  

UK PubMed Central (United Kingdom)

PurposeA prolonged seizure, status epileptics (SE), is a potent stimulus for increased neurogenesis in the dentate gyrus of the hippocampus. Molecular mechanisms...Full Text Available

2009-11-18

298

Seasonal proteomic changes reveal molecular adaptations to preserve and replenish liver proteins during ground squirrel hibernation  

UK PubMed Central (United Kingdom)

Hibernators are unique among mammals in their ability to survive extended periods of time with core body temperatures near freezing and with dramatically reduced heart, respiratory, and metabolic rates...Full Text Available

2010-02-01

299

Schindler disease: the molecular lesion in the alpha-N-acetylgalactosaminidase gene that causes an infantile neuroaxonal dystrophy.  

UK PubMed Central (United Kingdom)

Schindler disease is a recently recognized infantile neuroaxonal dystrophy resulting from the deficient activity of the lysosomal hydrolase, alpha-N-acetylgalctosaminidase (alpha-GalNAc). The recent...Full Text Available

1990-11-01

300

Roles of lead-binding proteins in mediating lead bioavailability.  

UK PubMed Central (United Kingdom)

The intracellular bioavailability of lead (Pb) at low dosage levels in major target organs such as the kidney and brain appears to be largely determined by complexation with a group of low molecular...Full Text Available

1998-12-01

301

Reduced PCR Sensitivity Due to Impaired DNA Recovery with the MagNA Pure LC Total Nucleic Acid Isolation Kit  

UK PubMed Central (United Kingdom)

The increasing demand for molecular diagnostics in clinical microbiology laboratories necessitates automated sample processing. In the present study, we evaluated the performance of the MagNA Pure LC...Full Text Available

2005-09-01

302

Rational design of DNA sequences for nanotechnology, microarrays and molecular computers using Eulerian graphs  

UK PubMed Central (United Kingdom)

Nucleic acids are molecules of choice for both established and emerging nanoscale technologies. These technologies benefit from large functional densities of ‘DNA processing elements’...Full Text Available

2004-01-01

303

Rapid evolution of sessility in an endemic species flock of the freshwater bivalve Corbicula from ancient lakes on Sulawesi, Indonesia  

UK PubMed Central (United Kingdom)

The fauna of ancient lakes frequently contains taxa with highly derived morphologies that resulted from in situ radiation of lacustrine lineages with high antiquity. We employed a molecular...Full Text Available

2006-03-22

304

Quantitative structure-activity relationships of insecticides and plant growth regulators: comparative studies toward understanding the molecular mechanism of action.  

UK PubMed Central (United Kingdom)

Emphasis was put on the comparative quantitative structure-activity approaches to the exploration of action mechanisms of structurally different classes of compounds showing the same type of activity...Full Text Available

1985-09-01

305

Process for purifying alumina  

Energy Technology Data Exchange (ETDEWEB)

In a process for separating insoluble red mud from Bayer process streams the improvement is described which comprises contacting and mixing a Bayer process stream with a tertiary polyamine having a molecular weight of at least about 10,000 in an amount effective to reduce the iron content thereof.

1988-01-05

306

Probing active galactic nuclei with H2O megamasers.  

UK PubMed Central (United Kingdom)

We describe the characteristics of the rapidly rotating molecular disk in the nucleus of the mildly active galaxy NGC4258. The morphology and kinematics of the disk are delineated by the point-like...Full Text Available

1995-12-05

307

ProMoST: A tool for calculating the pI and molecular mass of phosphorylated and modified proteins on 2 dimensional gels  

UK PubMed Central (United Kingdom)

Protein modifications such as phosphorylation are often studied by two-dimensional gel electrophoresis since the perturbation in the protein’s pI value is readily detected by this method....Full Text Available

2009-01-01

308

Precise Detection and Tracing of Trichoderma hamatum 382 in Compost-Amended Potting Mixes by Using Molecular Markers  

UK PubMed Central (United Kingdom)

Randomly amplified polymorphic DNA (RAPD) analysis and the PCR assay were used in combination with dilution plating on a semiselective medium to detect and enumerate propagules of Trichoderma...Full Text Available

1999-12-01

309

Pore region of TRPV3 ion channel is specifically required for heat-activation  

UK PubMed Central (United Kingdom)

Ion-channels can be activated (gated) by a variety of stimuli including chemicals, voltage, mechanical force or temperature. Whereas molecular mechanisms of ion-channel gating by chemicals and...Full Text Available

2008-09-01

310

Phylogenetic inference in Rafflesiales: the influence of rate heterogeneity and horizontal gene transfer  

UK PubMed Central (United Kingdom)

BackgroundThe phylogenetic relationships among the holoparasites of Rafflesiales have remained enigmatic for over a century. Recent molecular phylogenetic studies using the mitochondrial...Full Text Available

311

Phenotypic Anchoring of Acetaminophen-Induced Oxidative Stress with Gene Expression Profiles in Rat Liver  

UK PubMed Central (United Kingdom)

Toxicogenomics provides the ability to examine in greater detail the underlying molecular events that precede and accompany toxicity, thus allowing prediction of adverse events at much earlier...Full Text Available

2006-09-01

312

Perspective on post-menopausal osteoporosis: establishing an interdisciplinary understanding of the sequence of events from the molecular level to whole bone fractures  

UK PubMed Central (United Kingdom)

Current drug treatments for post-menopausal osteoporosis cannot eliminate bone fractures, possibly because the mechanisms responsible for bone loss are not fully understood. Although research within...Full Text Available

2010-03-06

313

Pathogenicity of molecularly cloned bovine leukemia virus.  

UK PubMed Central (United Kingdom)

To delineate the mechanisms of bovine leukemia virus (BLV) pathogenesis, four full-length BLV clones, 1, 8, 9, and 13, derived from the transformed cell line FLK-BLV and a clone construct, pBLV913,...Full Text Available

1993-12-01

314

Partial purification and characterization of the multiple molecular forms of staphylococcal clotting activity (coagulase).  

UK PubMed Central (United Kingdom)

The clotting activity of Staphylococcus aureus strain 104 was purified 46,000-fold, but absolute purity was not achieved. Carbohydrate content of the purified material was not more than 5%. Elution...Full Text Available

1981-12-01

315

Partial Purification and Characterization of Aminopeptidase II from Chara australis  

UK PubMed Central (United Kingdom)

Aminopeptidase II, one of the two major aminopeptidases in the giant alga Chara australis, was partially purified. Its molecular weight was estimated to be about 80,000 by gel permeation...Full Text Available

1989-02-01

316

Pancreatic cancer: molecular pathogenesis and new therapeutic targets  

UK PubMed Central (United Kingdom)

Patients with pancreatic cancer normally present with advanced disease that is lethal and notoriously difficult to treat. Survival has not improved dramatically, despite routine use of chemotherapy...Full Text Available

2009-07-01

317

PYRROLO[1,2-b][1,2,5]BENZOTHIADIAZEPINES (PBTDs) induce apoptosis in K562 cells  

UK PubMed Central (United Kingdom)

BackgroundThe objective of this study was to gain insight into the molecular mechanism of induced cell death (apoptosis) by PYRROLO [1,2-b][1,2,5]BENZOTHIADIAZEPINES...Full Text Available

318

PASBio: predicate-argument structures for event extraction in molecular biology  

UK PubMed Central (United Kingdom)

BackgroundThe exploitation of information extraction (IE), a technology aiming to provide instances of structured representations from free-form text, has been rapidly growing within...Full Text Available

319

Origins, evolution, and phenotypic impact of new genes  

UK PubMed Central (United Kingdom)

Ever since the pre-molecular era, the birth of new genes with novel functions has been considered to be a major contributor to adaptive evolutionary innovation. Here, I review the origin and evolution...Full Text Available

2010-10-01

320

On the spontaneous stochastic dynamics of a single gene: complexity of the molecular interplay at the promoter  

UK PubMed Central (United Kingdom)

BackgroundGene promoters can be in various epigenetic states and undergo interactions with many molecules in a highly transient, probabilistic and combinatorial way, resulting in...Full Text Available

321

On the sensitivity of IMRT dose optimization to the mathematical form of a biological imaging-based prescription function  

UK PubMed Central (United Kingdom)

Voxel-based prescriptions of deliberately non-uniform dose distributions based on molecular imaging, so-called dose painting or theragnostic radiation therapy, require specification of a transformation...Full Text Available

2009-03-21

322

O2-dependent methionine auxotrophy in Cu,Zn superoxide dismutase-deficient mutants of Saccharomyces cerevisiae.  

UK PubMed Central (United Kingdom)

Mutant strains of the yeast Saccharomyces cerevisiae which lack functional Cu,Zn superoxide dismutase (SOD-1) do not grow aerobically unless supplemented with methionine. The molecular basis of this...Full Text Available

1990-04-01

323

Natural selection and the molecular basis of electrophoretic variation at the coagulation F13B locus  

UK PubMed Central (United Kingdom)

Electrophoretic analysis of protein variation at the coagulation F13B locus has previously revealed three alleles, with alleles 1, 2, and 3 each being at high frequency in European,...Full Text Available

2009-02-01

324

NSF/Tokyo Report: MITI's Polymer Project  

Science.gov (United States)

... Highly-Functional Materials" was launched in JFY1996 under the New Materials field. This project was ... Bio-mimetic materials" (1) Advanced stimuli responsive materials (2) Harmonized molecular materials ...

325

Mutations affecting the development of the peripheral nervous system in Drosophila: a molecular screen for novel proteins.  

UK PubMed Central (United Kingdom)

In our quest for novel genes required for the development of the embryonic peripheral nervous system (PNS), we have performed three genetic screens using MAb 22C10 as a marker of terminally differentiated...Full Text Available

2000-12-01

326

Molecular resemblance of an AIDS-associated lymphoma and endemic Burkitt lymphomas: Implications for their pathogenesis  

International Nuclear Information System (INIS)

Non-Hodgkin lymphoma is a common feature of AIDS. Approximately 30-40% of these tumors exhibit clinical features suggestive of endemic Burkitt lymphoma: they are aggressive malignancies that occur in association with Epstein-Barr virus infection, they arise in the setting of immunosuppression, and they carry t(8;14) translocations without detectable rearrangement of the MYC oncogene. To understand the molecular basis of these parallels, the authors analyzed a case of Epstein-Barr-positive AIDS-associated undifferentiated lymphoma. Southern blots show that the tumor exhibits immunoglobulin joining segment rearrangement but no rearrangement of the MYC oncogene. Cloning of the rearranged joining segment allowed the isolation of recombinant clones encompassing the translocation breakpoint, and sequencing of the translocation junction disclosed that the breakpoint is situated 7 base pairs from the chromosome 14 site involved in a previously described endemic Burkitt ...

327

Molecular mechanisms of genetic adaptation to xenobiotic compounds.  

UK PubMed Central (United Kingdom)

Microorganisms in the environment can often adapt to use xenobiotic chemicals as novel growth and energy substrates. Specialized enzyme systems and metabolic pathways for the degradation of man-made...Full Text Available

1992-12-01

328

Molecular epidemiology of trimethoprim resistance among coagulase-negative staphylococci.  

UK PubMed Central (United Kingdom)

A 42% (70 of 167 isolates) incidence of resistance to 20 micrograms of trimethoprim per ml was found among clinical isolates of coagulase-negative staphylococci from two hospitals. A specific trimethoprim...Full Text Available

1987-11-01

329

Molecular epidemiology of Mycobacterium bovis in Texas and Mexico.  

UK PubMed Central (United Kingdom)

Seventy-nine Mycobacterium bovis isolates recovered from Mexican and Texas cattle were categorized into 16 and 25 distinct types on the basis of IS6110 and direct-repeat fingerprint patterns, respectively....Full Text Available

1996-09-01

330

Molecular dynamics of a ?B DNA element: base flipping via cross-strand intercalative stacking in a microsecond-scale simulation  

UK PubMed Central (United Kingdom)

The sequence-dependent structural variability and conformational dynamics of DNA play pivotal roles in many biological milieus, such as in the site-specific binding of transcription factors to target...Full Text Available

2008-09-01

331

Molecular determinants archetypical to the phylum Nematoda  

UK PubMed Central (United Kingdom)

BackgroundNematoda diverged from other animals between 600–1,200 million years ago and has become one of the most diverse animal phyla on earth. Most nematodes are free-living...Full Text Available

332

Molecular conservation of estrogen-response associated with cell cycle regulation, hormonal carcinogenesis and cancer in zebrafish and human cancer cell lines  

UK PubMed Central (United Kingdom)

BackgroundThe zebrafish is recognized as a versatile cancer and drug screening model. However, it is not known whether the estrogen-responsive genes and signaling pathways that are...Full Text Available

333

Molecular conformation, receptor binding, and hormone action of natural and synthetic estrogens and antiestrogens.  

UK PubMed Central (United Kingdom)

The X-ray crystallographic structural determinations of synthetic estrogens and antiestrogens provide reliable information on the global minimum energy conformation of these molecules or a local minimum...Full Text Available

1985-09-01

334

Molecular cloning and nucleotide sequence of the beta-lytic protease gene from Achromobacter lyticus.  

UK PubMed Central (United Kingdom)

Two bacteriolytic enzymes secreted by Achromobacter lyticus M497-1 were purified and identified as being very similar (considering their amino acid composition and N-terminal sequence) to alpha- and...Full Text Available

1990-11-01

335

Molecular cloning and functional expression of geranylgeranyl pyrophosphate synthase from Coleus forskohlii Briq  

UK PubMed Central (United Kingdom)

BackgroundIsopentenyl diphosphate (IPP), a common biosynthetic precursor to the labdane diterpene forskolin, has been biosynthesised via a non-mevalonate pathway. Geranylgeranyl...Full Text Available

336

Molecular characterization of hepatitis A virus isolates from environmental and clinical samples in Greece  

UK PubMed Central (United Kingdom)

BackgroundHepatitis A virus (HAV) strains detected in environmental and clinical samples were analysed to characterize the genotypes of HAV circulating in Greece. Fifty (50) sewage...Full Text Available

337

Molecular characterization of a unique retrovirus associated with a fish tumor.  

UK PubMed Central (United Kingdom)

The walleye dermal sarcoma is a mesenchymal tumor which seasonally affects up to 27% of adult walleye fish (Stizostedion vitreum). It arises multicentrically in the dermis, in which its development...Full Text Available

1992-01-01

338

Molecular characterization of a mannoprotein with homology to chitin deacetylases that stimulates T cell responses to Cryptococcus neoformans  

UK PubMed Central (United Kingdom)

The fungus Cryptococcus neoformans is a major cause of morbidity and mortality in patients with impaired CD4+ T cell function, particularly those with AIDS. To identify...Full Text Available

2001-08-28

339

Molecular characterization of a Chinese variant of the Flury-LEP strain  

UK PubMed Central (United Kingdom)

The entire genome of rabies virus vaccine strain Flury-LEP-C, a Chinese variant of the rabies virus vaccine strain Flury-LEP, was sequenced. The overall length of the genome of Flury-LEP-C strain was...Full Text Available

340

Molecular breeding of cereals for aluminium resistance  

Science.gov (United States)

Aluminium (Al3+) toxicity is the primary factor limiting crop production on acidic soils worldwide. In addition to an application of lime for soil amelioration, Al3+ resistant plant varieties have been deployed to raise productivity on such hostile soils. This has been possible due to the exploita...

341

Molecular basis of the inhibition of human aromatase (estrogen synthetase) by flavone and isoflavone phytoestrogens: A site-directed mutagenesis study.  

UK PubMed Central (United Kingdom)

Flavone and isoflavone phytoestrogens are plant chemicals and are known to be competitive inhibitors of cytochrome P450 aromatase with respect to the androgen substrate. Aromatase is the enzyme that...Full Text Available

1998-02-01

342

Molecular basis of FIR-mediated c-myc transcriptional control  

UK PubMed Central (United Kingdom)

The Far UpStream Element (FUSE) regulatory system promotes a peak in the concentration of c-Myc during cell cycle. First, the FBP transcriptional activator binds to the FUSE DNA element upstream...Full Text Available

2010-09-01

343

Molecular and immunological comparison of human dihydropteridine reductase in liver, cultured fibroblasts and continuous lymphoid cells.  

UK PubMed Central (United Kingdom)

An antiserum was raised in a rabbit against highly purified human liver dihydropteridine reductase (EC 1.6.99.7). Dihydropteridine reductase from human liver, in human cultured fibroblasts and in continuous...Full Text Available

1981-07-01

344

Molecular and immunological analysis of a polymorphic periplasmic protein of Borrelia burgdorferi.  

UK PubMed Central (United Kingdom)

Borrelia burgdorferi is the causative agent of Lyme disease, a tick-borne spirochetosis with a worldwide prevalence. To assist the categorization and typing of fresh isolates from global foci, we have...Full Text Available

1991-09-01

345

Molecular and clinico-pathological markers in rectal cancer: a tissue micro-array study  

UK PubMed Central (United Kingdom)

AimsThe aims of the study were to study the effect of pre-operative treatment on the expression of tumour-related proteins and to correlate the expression of these...Full Text Available

2009-02-01

346

Molecular and Kinetic Comparison of the Novel Extended-Spectrum ?-Lactamases CTX-M-25 and CTX-M-26  

UK PubMed Central (United Kingdom)

CTX-M-25 is a novel extended-spectrum β-lactamase isolated from a single Canadian Escherichia coli isolate. Susceptibility testing demonstrated that this enzyme confers resistance...Full Text Available

2004-12-01

347

Molecular Variability of Pseudallescheria boydii, a Neurotropic Opportunist  

UK PubMed Central (United Kingdom)

The sequences of the internal transcribed spacer (ITS) ribosomal DNA (rDNA) domain data obtained by restriction fragment length polymorphism analysis with 18S rDNA and fingerprinting (M13) for clinical...Full Text Available

2000-09-01

348

Molecular Mechanistic Insights into the Endothelial Receptor Mediated Cytoadherence of Plasmodium falciparum-Infected Erythrocytes  

UK PubMed Central (United Kingdom)

Cytoadherence or sequestration is essential for the pathogenesis of the most virulent human malaria species, Plasmodium falciparum (P. falciparum). Similar to leukocyte-endothelium...Full Text Available

349

Molecular Mapping of Movement-Associated Areas in the Avian Brain: A Motor Theory for Vocal Learning Origin  

UK PubMed Central (United Kingdom)

Vocal learning is a critical behavioral substrate for spoken human language. It is a rare trait found in three distantly related groups of birds-songbirds, hummingbirds, and parrots. These avian groups...Full Text Available

350

Molecular Identification and Expression Analysis of Filaggrin-2, a Member of the S100 Fused-Type Protein Family  

UK PubMed Central (United Kingdom)

Genes of the S100 fused-type protein (SFTP) family are clustered within the epidermal differentiation complex and encode essential components that maintain epithelial homeostasis and barrier functions....Full Text Available

351

Molecular Evidence of Bartonella Infection in Domestic Dogs from Algeria, North Africa, by Polymerase Chain Reaction (PCR)  

UK PubMed Central (United Kingdom)

Bartonella species are being recognized as important bacterial human and canine pathogens, and are associated with multiple arthropod vectors. Bartonella DNA extracted...Full Text Available

2010-08-05

352

Molecular Epidemiology of Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus Isolated from the Eye  

UK PubMed Central (United Kingdom)

Purpose:Methicillin-resistant Staphylococcus aureus (MRSA) strains are commonly classified as hospital-acquired (HA) or community-acquired (CA). Typical HA-MRSA...Full Text Available

2011-02-01

353

Molecular Epidemiology of Escherichia coli Producing Extended-Spectrum ?-Lactamases Isolated in Rome, Italy?  

UK PubMed Central (United Kingdom)

Escherichia coli strains producing extended-spectrum β-lactamases (ESBLs) are a major problem in many different hospitals worldwide, causing outbreaks as well as sporadic infections....Full Text Available

2008-01-01

354

Molecular Ecology of Pyrethroid Knockdown Resistance in Culex pipiens pallens Mosquitoes  

UK PubMed Central (United Kingdom)

Pyrethroid insecticides have been extensively used in China and worldwide for public health pest control. Accurate resistance monitoring is essential to guide the rational use of insecticides and resistance...Full Text Available

356

Molecular Characterization of Exploitation of the Polyubiquitination and Farnesylation Machineries of Dictyostelium Discoideum by the AnkB F-Box Effector of Legionella Pneumophila  

UK PubMed Central (United Kingdom)

The Dot/Icm-translocated Ankyrin B (AnkB) F-box effector of Legionella pneumophila is essential for intra-vacuolar proliferation and functions as a platform for the docking of polyubiquitinated...Full Text Available

357

Molecular Characterization of Aluminium (aluminum) Tolerance in Rye  

Science.gov (United States)

Aluminium (Al) toxicity, affecting around half of the world¿s arable land, severely hinders the ability of crop plants to utilize moisture and nutrients by restricting root growth and function. Among the cultivated cereals, rye is the most Al-tolerant and represents an important potential source of ...

358

Molecular Architecture of the Centriole Proteome: The Conserved WD40 Domain Protein POC1 Is Required for Centriole Duplication and Length Control  

UK PubMed Central (United Kingdom)

Centrioles are intriguing cylindrical organelles composed of triplet microtubules. Proteomic data suggest that a large number of proteins besides tubulin are necessary for the formation and maintenance...Full Text Available

2009-02-15

359

Molecular Analysis of a Novel Methanesulfonic Acid Monooxygenase from the Methylotroph Methylosulfonomonas methylovora  

UK PubMed Central (United Kingdom)

Methylosulfonomonas methylovora M2 is an unusual gram-negative methylotrophic bacterium that can grow on methanesulfonic acid (MSA) as the sole source of carbon and energy. Oxidation...Full Text Available

1999-04-01

360

Molecular Analyses of Salmonellaenterica Isolates from Fish Feed Factories and Fish Feed Ingredients  

UK PubMed Central (United Kingdom)

Isolates of the most commonly observed salmonella serovars in Norwegian fish feed factories from 1998 to 2000 (Salmonella enterica serovar Agona, S. enterica...Full Text Available

2003-02-01

361

Methylprednisolone acetate induced release of cartilage proteoglycans: determination by high performance liquid chromatography.  

UK PubMed Central (United Kingdom)

A high performance liquid chromatography (HPLC) procedure suitable for the simultaneous determination of the molecular size and concentration of macromolecular hyaluronate and proteoglycans in synovial...Full Text Available

1992-02-01

362

Methanogen Diversity Evidenced by Molecular Characterization of Methyl Coenzyme M Reductase A (mcrA) Genes in Hydrothermal Sediments of the Guaymas Basin  

UK PubMed Central (United Kingdom)

The methanogenic community in hydrothermally active sediments of Guaymas Basin (Gulf of California, Mexico) was analyzed by PCR amplification, cloning, and sequencing of methyl coenzyme M reductase...Full Text Available

2005-08-01

363

Metal Ions-Stimulated Iron Oxidation in Hydroxylases Facilitates Stabilization of HIF-1? Protein  

UK PubMed Central (United Kingdom)

The exposure of cells to several metal ions stabilizes HIF-1α protein. However, the molecular mechanisms are not completely understood. They may involve inhibition of hydroxylation by either...Full Text Available

2009-02-01

364

Mapping the cellular and molecular heterogeneity of normal and malignant breast tissues and cultured cell lines  

UK PubMed Central (United Kingdom)

IntroductionNormal and neoplastic breast tissues are comprised of heterogeneous populations of epithelial cells exhibiting various degrees of maturation and differentiation. While...Full Text Available

2010-01-01

365

Mapping Drug Physico-Chemical Features to Pathway Activity Reveals Molecular Networks Linked to Toxicity Outcome  

UK PubMed Central (United Kingdom)

The identification of predictive biomarkers is at the core of modern toxicology. So far, a number of approaches have been proposed. These rely on statistical inference of toxicity response from either...Full Text Available

366

Lymphoma depletion during CD20 immunotherapy in mice is mediated by macrophage Fc?RI, Fc?RIII, and Fc?RIV  

UK PubMed Central (United Kingdom)

Despite the demonstrated clinical efficacy of CD20 monoclonal antibody (mAb) for lymphoma therapy, the in vivo mechanisms of tumor depletion remain controversial and variable. To identify the molecular...Full Text Available

2008-08-15

367

Location of an epitopic site on epiglycanin by molecular immunoelectron microscopy.  

UK PubMed Central (United Kingdom)

Antibodies of the IgM type present in rabbit anti-epiglycanin antiserum were purified by (NH4)2SO4 precipitation and by ion-exchange, affinity and gel-filtration chromatography. After papain treatment...Full Text Available

1985-04-01

368

Is X(1812) a $(K^*\\bar K^*)$ Molecular State?  

CERN Document Server

We investigate the possibility of producing the $\\omega\\phi$ threshold enhancement recently observed in the $J\\psi\\to\\gamma X(1812),~X(1812)\\to\\omega\\phi$ at BES by assuming the X(1812) to be a candidate of $(K^{*}\\bar K^{*0})$ molecular state. We evaluate the decay rate of $X(1812)\\to\\eta\\eta', \\eta\\eta, \\omega\\phi, K^+K^-, \\rho^+\\rho^-$, $\\omega\\omega, K^{*+}K^{*-}$ and $\\pi^+\\pi^-$ based on the X(1812) to be a candidate of $(\\ksks)$ molecule. It turns out the X(1812) dominantly decays into $\\eta\\eta'$ and $\\eta\\eta$. These channels are suggested to be the laboratory to test the molecular scenario in experiment. We also evaluate the branching fraction $Br(X\\to\\omega\\phi)\\simeq 4.60%$. However, the X(1812) has small branching fractions to decay into other $VV$ or $PP$ final states, from which it seems to be consistent with the experimental observation. In the molecular scenario, the X(1812) ...

2007-01-01

369

Involvement of a low-molecular-weight substance in in vitro activation of the molybdoenzyme respiratory nitrate reductase from a chlB mutant of Escherichia coli.  

UK PubMed Central (United Kingdom)

The soluble subcellular fraction of a chlB mutant contains an inactive precursor form of the molybdoenzyme nitrate reductase, which can be activated by the addition to the soluble fraction of protein...Full Text Available

1987-10-01

370

Investigations into the nature of a silicoaluminophosphate with the faujasite structure  

Energy Technology Data Exchange (ETDEWEB)

The physicochemical nature of a silicoaluminophosphate with the faujasite structure has been studied. The molecular sieve framework contains a homogeneous distribution of silicon, aluminum, and phosphorus and is negatively charged. Combustion in air of the charge-compensating organic cations produces hydroxyl groups which exhibit Broensted acidity.

1987-04-29

371

IntelliGO: a new vector-based semantic similarity measure including annotation origin  

UK PubMed Central (United Kingdom)

BackgroundThe Gene Ontology (GO) is a well known controlled vocabulary describing the biological process, molecular function and cellular...Full Text Available

372

Increases in mouse uterine heat shock protein levels are a sensitive and specific response to uterotrophic agents.  

UK PubMed Central (United Kingdom)

There is increasing consensus that the uterotrophic estrogenicity assay should be coupled with other morphometric or molecular end points that might enhance its sensitivity. We have previously shown...Full Text Available

2002-12-01

373

Increased SRF transcriptional activity in human and mouse skeletal muscle is a signature of insulin resistance  

UK PubMed Central (United Kingdom)

Insulin resistance in skeletal muscle is a key phenotype associated with type 2 diabetes (T2D) for which the molecular mediators remain unclear. We therefore conducted an expression analysis of human...Full Text Available

2011-03-01

374

Identification of a Novel Inhibitor of Coactivator-associated Arginine Methyltransferase 1 (CARM1)-mediated Methylation of Histone H3 Arg-17*  

UK PubMed Central (United Kingdom)

Methylation of the arginine residues of histones by methyltransferases has important consequences for chromatin structure and gene regulation; however, the molecular mechanism(s) of methyltransferase...Full Text Available

2010-03-05

375

Identification of Potential Calorie Restriction-Mimicking Yeast Mutants with Increased Mitochondrial Respiratory Chain and Nitric Oxide Levels  

UK PubMed Central (United Kingdom)

Calorie restriction (CR) induces a metabolic shift towards mitochondrial respiration; however, molecular mechanisms underlying CR remain unclear. Recent studies suggest that CR-induced mitochondrial...Full Text Available

376

Identification and mobilization by cointegrate formation of a nodulation plasmid in Rhizobium trifolii.  

UK PubMed Central (United Kingdom)

A nodulation plasmid, pRtr-514a, of molecular size 180 megadaltons (Mdal) was identified in Rhizobium trifolii strain NZP514. This plasmid was absent in both spontaneous and heat-cured Nod- derivatives...Full Text Available

1982-07-01

377

Human mitochondrial transcription factor A reduction and mitochondrial dysfunction in Hashimoto's hypothyroid myopathy.  

UK PubMed Central (United Kingdom)

BACKGROUND: Mitochondrial changes have been described in muscle tissue in acquired hypothyroidism. Among the molecular mechanisms by which thyroid hormones regulate expression of nuclear genes encoding...Full Text Available

2002-06-01

378

Hsp12.6 Expression Is Inducible by Host Immunity in Adult Worms of the Parasitic Nematode Nippostrongylus brasiliensis  

UK PubMed Central (United Kingdom)

Heat shock proteins (Hsp) are a family of stress-inducible molecular chaperones that play multiple roles in a wide variety of animals. However, the roles of Hsps in parasitic nematodes remain largely...Full Text Available

379

High-resolution infrared observations in IC 5146  

Energy Technology Data Exchange (ETDEWEB)

High-resolution near-infrared and far-infrared observations are presented of the southeastern molecular cloud fragment in the IC 5146 dark cloud. These observations rule out earlier suggestions for the formation of massive stars in this fragment.

1984-04-01

380

High Glucose-Mediated Oxidative Stress Impairs Cell Migration  

UK PubMed Central (United Kingdom)

Deficient wound healing in diabetic patients is very frequent, but the cellular and molecular causes are poorly defined. In this study, we evaluate the hypothesis that high glucose concentrations inhibit...Full Text Available

381

Genome-wide characterization of simple sequence repeats in cucumber (Cucumis sativus L.)  

UK PubMed Central (United Kingdom)

BackgroundCucumber, Cucumis sativus L. is an important vegetable crop worldwide. Until very recently, cucumber genetic and genomic resources, especially molecular...Full Text Available

382

Genetics and molecular pathology of Stargardt-like macular degeneration  

UK PubMed Central (United Kingdom)

Stargardt-like macular degeneration (STGD3) is an early onset, autosomal dominant macular degeneration. STGD3 is characterized by a progressive pathology, the loss of central vision, atrophy...Full Text Available

2010-05-01

383

Gadolinium-containing phosphatidylserine liposomes for molecular imaging of atherosclerosis  

UK PubMed Central (United Kingdom)

Exteriorized phosphatidylserine (PS) residues in apoptotic cells trigger rapid phagocytosis by macrophage scavenger receptor pathways. Mimicking apoptosis with liposomes containing PS may represent...Full Text Available

2009-11-01

384

Fluorine-19 NMR Chemical Shift Probes Molecular Binding to Lipid Membranes  

UK PubMed Central (United Kingdom)

The binding of amphiphilic molecules to lipid bilayers is followed by 19F NMR using chemical shift and line shape differences between the solution and membrane-tethered states of...Full Text Available

2008-05-22

385

Evolution of feeding specialization in Tanganyikan scale-eating cichlids: a molecular phylogenetic approach  

UK PubMed Central (United Kingdom)

BackgroundCichlid fishes in Lake Tanganyika exhibit remarkable diversity in their feeding habits. Among them, seven species in the genus Perissodus are known for...Full Text Available

386

Enzymatic control of anhydrobiosis-related accumulation of trehalose in the sleeping chironomid, Polypedilum vanderplanki  

UK PubMed Central (United Kingdom)

Larvae of an anhydrobiotic insect, Polypedilum vanderplanki, accumulate very large amounts of trehalose as a compatible solute on desiccation, but the molecular mechanisms underlying...Full Text Available

2010-10-01

387

Engineering ligand-responsive RNA controllers in yeast through the assembly of RNase III tuning modules  

UK PubMed Central (United Kingdom)

The programming of cellular networks to achieve new biological functions depends on the development of genetic tools that link the presence of a molecular signal to gene-regulatory activity. Recently,...Full Text Available

2011-07-01

388

Efficacy and Safety of Low-Molecular-Weight Heparins As An Adjunct to Thrombolysis in Acute ST-Elevation Myocardial Infarction  

UK PubMed Central (United Kingdom)

A 48-hour course of intravenous unfractionated heparin (UFH) is the standard of treatment in conjunction with fibrin-specific thrombolysis in ST-elevation myocardial infarction (STEMI). In recent trials,...Full Text Available

2008-02-01

389

Dual-channel imaging system for singlet oxygen and photosensitizer for PDT  

UK PubMed Central (United Kingdom)

A two-channel optical system has been developed to provide spatially resolved simultaneous imaging of singlet molecular oxygen (1O2) phosphorescence and photosensitizer (PS) fluorescence...Full Text Available

390

Does Damage to DNA and Other Macromolecules Play a Role in Aging? If So, How?  

UK PubMed Central (United Kingdom)

One of the most pervasive ideas regarding the causes of aging is that longevity is constrained in large measure by damage to macromolecules. An increasing body of cellular and molecular data, generated...Full Text Available

2009-02-01

391

Dissecting the Genetic Components of Adaptation of Escherichia coli to the Mouse Gut  

UK PubMed Central (United Kingdom)

While pleiotropic adaptive mutations are thought to be central for evolution, little is known on the downstream molecular effects allowing adaptation to complex ecologically relevant environments. Here...Full Text Available

2008-01-01

392

Discrete molecular states in the brain accompany changing responses to a vocal signal  

UK PubMed Central (United Kingdom)

New experiences can trigger changes in gene expression in the brain. To understand this phenomenon better, we studied zebra finches hearing playbacks of birdsong. Earlier research had shown that initial...Full Text Available

2009-07-07

393

Development of an extrachromosomal cloning vector system for use in Borrelia burgdorferi  

UK PubMed Central (United Kingdom)

Molecular genetic analysis of Borrelia burgdorferi, the cause of Lyme disease, has been hampered by the absence of any means of efficient generation, identification, and complementation...Full Text Available

2000-04-25

394

Detection of Unculturable Bacteria in Periodontal Health and Disease by PCR  

UK PubMed Central (United Kingdom)

Recently developed molecular methods have made it possible to characterize mixed microflora in their entirety, including the substantial numbers of bacteria which do not grow on artificial culture media....Full Text Available

1999-05-01

395

Destructive effects of smoking on molecular and genetic factors of periodontal disease  

UK PubMed Central (United Kingdom)

Many epidemiological evidences have proven the association between smoking and periodontal disease. The causality can be further established by linking findings of traditional epidemiological studies...Full Text Available

396

Cyclodextrin Inclusion Complexes with Bimanes and Other ...  

Science.gov (United States)

... HE*MS-1 and HE*MS-1.6: Hydroxyethyl Betacyclodextrin with averaae molecular substitution of 1 and 1.6 respectively HPeMS=0.6 and HP*MS-0.9 ...

1991-07-09

397

Conservation of spermatogonial stem cell self-renewal signaling between mouse and rat  

UK PubMed Central (United Kingdom)

Self-renewal of spermatogonial stem cells (SSCs) is the foundation for maintenance of spermatogenesis throughout life in males and for continuation of a species. The molecular mechanism underlying stem...Full Text Available

2005-10-04

398

Computer simulation of protein self-association during small-zone gel filtration. Estimation of equilibrium constants.  

UK PubMed Central (United Kingdom)

A simulation is developed that qualitatively describes the small-zone-gel-filtration behaviour of a reversibly associating protein. The results reflect the dependence of the apparent molecular weight...Full Text Available

1981-04-01

399

Comprehensive molecular cytogenetic analysis of sorghum genome architecture: distribution of euchromatin, ...  

Science.gov (United States)

Cyteogenetic maps of sorghum chromosomes 3-7, 9, and 10 were constructed on the basis of the fluorescence in situ hybridization (FISH) of ~ ... regions of heterchromatin were delimited for all 10 sorghum chrom...

400

Comprehensive SNP-chip for retinitis pigmentosa-Leber congenital amaurosis diagnosis: new mutations and detection of mutational founder effects  

UK PubMed Central (United Kingdom)

Fast and efficient high-throughput techniques are essential for the molecular diagnosis of highly heterogeneous hereditary diseases, such as retinitis pigmentosa (RP). We had previously approached RP...Full Text Available

2010-01-01

401

Complete chloroplast genome of Oncidium Gower Ramsey and evaluation of molecular markers for identification and breeding in Oncidiinae  

UK PubMed Central (United Kingdom)

BackgroundOncidium spp. produce commercially important orchid cut flowers. However, they are amenable to intergeneric and inter-specific crossing making phylogenetic...Full Text Available

402

Comparative transcripts profiling reveals new insight into molecular processes regulating lycopene accumulation in a sweet orange (Citrus sinensis) red-flesh mutant  

UK PubMed Central (United Kingdom)

BackgroundInterest in lycopene metabolism and regulation is growing rapidly because accumulative studies have suggested an important role for lycopene in human health promotion....Full Text Available

403

Comparative nucleic acid transfection efficacy in primary hepatocytes for gene silencing and functional studies  

UK PubMed Central (United Kingdom)

BackgroundPrimary hepatocytes are the best resource for in vitro studies directed at understanding hepatic processes at the cellular and molecular levels, necessary...Full Text Available

404

Common variation in the ABO glycosyltransferase is associated with susceptibility to severe Plasmodium falciparum malaria  

UK PubMed Central (United Kingdom)

There is growing epidemiological and molecular evidence that ABO blood group affects host susceptibility to severe Plasmodium falciparum infection. The high frequency of common...Full Text Available

2008-02-15

405

Common mitochondrial polymorphisms as risk factor for endometrial cancer  

UK PubMed Central (United Kingdom)

Endometrial carcinoma is the most commonly diagnosed gynaecological cancer in developed countries. Although the molecular genetics of this disease has been in the focus of many research laboratories...Full Text Available

406

Chromosome location of Oryza sativa recombination linkage groups.  

UK PubMed Central (United Kingdom)

In situ hybridization, a powerful tool for the molecular cytogeneticist, can be used to physically map repetitive, low-copy, and unique DNA sequences in plant chromosomes. With the availability of a...Full Text Available

1992-09-15

407

Characterization of the Molecular Mechanism of Defective Interfering RNA-Mediated Symptom Attenuation in Tombusvirus-Infected Plants  

UK PubMed Central (United Kingdom)

Different tombusviruses were able to support the replication of either homologous or heterologous defective interfering (DI) RNAs, and those infected plants usually developed typical attenuated symptoms....Full Text Available

1998-07-01

408

Characterization of Two New Genes, amoR and amoD, in the amo Operon of the Marine Ammonia Oxidizer Nitrosococcus oceani ATCC 19707?  

UK PubMed Central (United Kingdom)

Molecular analysis of the amo gene cluster in Nitrosococcus oceani revealed that it consists of five genes, instead of the three known genes, amoCAB....Full Text Available

2008-01-01

409

Characterization of T-Even Bacteriophage Substructures  

UK PubMed Central (United Kingdom)

Tail plates obtained from T4D amber mutants were examined with respect to sedimentation behavior, subunit molecular weights, amino acid composition, isoelectric points, and morphology. Intact plates...Full Text Available

1970-10-01

410

Cellulase-Xylanase Synergy in Designer Cellulosomes for Enhanced Degradation of a Complex Cellulosic Substrate  

UK PubMed Central (United Kingdom)

Designer cellulosomes are precision-engineered multienzyme complexes in which the molecular architecture and enzyme content are exquisitely controlled. This system was used to examine enzyme cooperation...Full Text Available

411

Cd36, a class B scavenger receptor, functions as a monomer to bind acetylated and oxidized low-density lipoproteins  

UK PubMed Central (United Kingdom)

Cd36 is a small-molecular-weight integral membrane protein expressed in a diverse, but select, range of cell types. It has an equally diverse range of ligands and physiological functions, which has...Full Text Available

2007-11-01

412

Can circular dichroism in core-level photoemission provide a spectral fingerprint of adsorbed chiral molecules?  

International Nuclear Information System (INIS)

The results of experimental measurements and theoretical simulations of circular dichroism in the angular distribution (CDAD) of photoemission from atomic core levels of each of the enantiomers of a chiral molecule, alanine, adsorbed on Cu(1 1 0) are presented. Measurements in, and out of, substrate mirror planes allow one to distinguish the CDAD due to the chirality of the sample from that due to a chiral experimental geometry. For these studies of oriented chiral molecules, the CDAD is seen not only in photoemission from the molecular chiral centre, but also from other atoms which have chiral geometries as a result of the adsorption. The magnitude of the CDAD due to the sample chirality differs for different adsorption phases of alanine, and for different emission angles and energies, but is generally small compared with CDAD out of the substrate mirror planes which is largely unrelated to the molecular chirality. While similar measurements ...

2005-04-01

413

Calorimetric studies of the kinetic unfreezing of molecular motions in hydrated lysozyme, hemoglobin, and myoglobin.  

UK PubMed Central (United Kingdom)

Differential scanning calorimetric (DSC) studies of the glassy states of as-received and hydrated lysozyme, hemoglobin, and myoglobin powders, with water contents of < or = 0.25, < or...Full Text Available

1994-01-01

414

CTX-M-Type Extended-Spectrum ?-Lactamases in Italy: Molecular Epidemiology of an Emerging Countrywide Problem  

UK PubMed Central (United Kingdom)

A nationwide survey of extended-spectrum β-lactamase (ESBL) production among Enterobacteriaceae, carried out in 2003, showed that CTX-M-type enzymes have achieved a sizeable...Full Text Available

2006-08-01

415

Boundary conditions for the paleoenvironment: chemical and physical processes in the pre-solar nebula  

Energy Technology Data Exchange (ETDEWEB)

Two additional hyperfine components of the interstellar radical C3H were detected. In addition, methanol was discovered in interstellar clouds. The abundance of HCCN and various chemical isomers in molecular clouds was investigated.

1985-02-01

416

Boule and the Evolutionary Origin of Metazoan Gametogenesis: A Grandpa's Tale  

UK PubMed Central (United Kingdom)

The evolution of sex remains a hotly debated topic in evolutionary biology. In particular, studying the origins of the molecular mechanisms underlying sexual reproduction and gametogenesis (its fundamental...Full Text Available

417

Biochemical characterization of the molecular interaction between recombinant basic fibroblast growth factor and a recombinant soluble fibroblast growth factor receptor.  

UK PubMed Central (United Kingdom)

The extracellular domain of human fibroblast growth factor receptor (XC-FGF-R) was expressed in Escherichia coli. The protein was purified to homogeneity and the interaction with basic fibroblast growth...Full Text Available

1993-09-15

418

Behavioral Defects in Chaperone-Deficient Alzheimer's Disease Model Mice  

UK PubMed Central (United Kingdom)

Molecular chaperones protect cells from the deleterious effects of protein misfolding and aggregation. Neurotoxicity of amyloid-beta (Aβ) aggregates and their deposition in senile plaques are...Full Text Available

419

Avian Nephritis Virus (ANV) as a New Member of the Family Astroviridae and Construction of Infectious ANV cDNA  

UK PubMed Central (United Kingdom)

The complete RNA genome of the avian nephritis virus (ANV) associated with acute nephritis in chickens has been molecularly cloned and sequenced. Excluding the poly(A) tail, the genome comprises 6,927...Full Text Available

2000-09-01

420

Application of the PM6 semi-empirical method to modeling proteins enhances docking accuracy of AutoDock  

UK PubMed Central (United Kingdom)

BackgroundMolecular docking methods are commonly used for predicting binding modes and energies of ligands to proteins. For accurate complex geometry and binding energy estimation,...Full Text Available

421

Androgens and spermatogenesis: lessons from transgenic mouse models  

UK PubMed Central (United Kingdom)

Transgenic mouse models have contributed considerably to our understanding of the cellular and molecular mechanisms by which androgens control spermatogenesis. Cell-selective ablation of the androgen...Full Text Available

2010-05-27

422

Acute Ozone-Induced Differential Gene Expression Profiles in Rat Lung  

UK PubMed Central (United Kingdom)

Ozone (O3) is an oxidant gas that can directly induce lung injury. Knowledge of the initial molecular events of the acute O3 response would be useful in developing biomarkers of...Full Text Available

2005-12-01

423

A study in molecular contingency: glutamine phosphoribosylpyrophosphate amidotransferase is a promiscuous and evolvable phosphoribosylanthranilate isomerase  

UK PubMed Central (United Kingdom)

SummaryThe prevalence of paralogous enzymes implies that novel catalytic functions can evolve on preexisting protein scaffolds. The weak secondary activities of proteins, which...Full Text Available

2008-03-21

424

A rationale for stabilization of oxygen-labile enzymes: application to a clostridial hydrogenase.  

UK PubMed Central (United Kingdom)

A general procedure for stabilization of O2-labile enzymes exploiting "salting out" of oxygen from the microenvironment in the molecular layers immediately adjacent to charged surfaces of polyionic...Full Text Available

1978-08-01

425

A molecular epidemiological study of rabies epizootics in kudu (Tragelaphus strepsiceros) in Namibia  

UK PubMed Central (United Kingdom)

BackgroundA panel of 37 rabies virus isolates were collected and studied, originating mainly from the northern and central regions of Namibia, between 1980 and 2003.ResultsThese...Full Text Available

426

A homozygous P86S mutation of the human glucagon receptor is associated with hyperglucagonemia, ? cell hyperplasia, and islet cell tumor  

UK PubMed Central (United Kingdom)

ObjectiveThe goal of the study was to investigate the genetic and molecular basis of a novel syndrome of marked hyperglucagonemia and pancreatic α cell hyperplasia...Full Text Available

2009-11-01

427

A Novel Nuclear-Localized CCCH-Type Zinc Finger Protein, OsDOS, Is Involved in Delaying Leaf Senescence in Rice1[W  

UK PubMed Central (United Kingdom)

Leaf senescence is a developmentally programmed degeneration process, which is fine tuned by a complex regulatory network for plant fitness. However, molecular regulation of leaf senescence is poorly...Full Text Available

2006-08-01

428

A Novel Information Retrieval Model for High-Throughput Molecular Medicine Modalities  

UK PubMed Central (United Kingdom)

Significant research has been devoted to predicting diagnosis, prognosis, and response to treatment using high-throughput assays. Rapid translation into clinical results hinges upon efficient access...Full Text Available

429

A NEW APPROACH TO UNDERSTANDING THE MOLECULAR MECHANISMS THROUGH WHICH ESTROGENS AFFECT COGNITION  

UK PubMed Central (United Kingdom)

Traditional approaches to the study of hormones and cognition have been primarily observational or correlational in nature. Because this work does not permit causal relationships to be identified,...Full Text Available

2010-10-01

430

A Master Conductor for Aggregate Clearance by Autophagy  

UK PubMed Central (United Kingdom)

Autophagic adapters including p62/SQSTM1 recognize polyubiquitinated autophagic targets such as toxic protein aggregates. Recently reporting in Molecular Cell, Filimonenko et al. provide evidence...Full Text Available

2010-05-18

431

A Decline in p38 MAPK Signaling Underlies Immunosenescence in Caenorhabditis elegans  

UK PubMed Central (United Kingdom)

The decline in immune function with aging, known as immunosenescence, has been implicated in evolutionarily diverse species, but the underlying molecular mechanisms are not understood. During aging...Full Text Available

2011-05-01

432

A Comprehensive Analysis of the Dynamic Biological Networks in HCV Induced Hepatocarcinogenesis  

UK PubMed Central (United Kingdom)

Hepatocellular carcinoma (HCC) is a primary malignancy of the liver, which is closely related to hepatitis C and cirrhosis. The molecular mechanisms underlying the hepatocarcinogenesis induced by HCV...Full Text Available

433

1980-1990 - NASA Technical Report Server (NTRS)  

Science.gov (United States)

of the soleus in 6-mercaptopurine-treated rats. Experimental and Molecular Pathology. 43: 74-81, 1985. (GWU 5998). Jaweed, M.M.; Bozentka, D.; Hume, E.L.; ...

434

Towards an understanding of the light scalar mesons  

Energy Technology Data Exchange (ETDEWEB)

Although studied for many years the nature of the light scalar mesons remains controversial. Here we shall present a method, applicable for s-wave states located close to a threshold, that allows one to quantify the molecular part of a given state. When applied to the f{sub 0}(980) a dominance of the molecular component is found. In the second part, we show that requirements of field-theoretic consistency and chiral symmetry, when applied to the scattering of light pseudo-scalars, naturally lead to the appearance of dynamical poles in the scalar sector. A program is proposed on how to further investigate experimentally the mixing between these dynamical states and possible genuine quark states. (orig.)

2007-03-15

435

Review of the application of molecular beam epitaxy for high efficiency solar cell research  

Energy Technology Data Exchange (ETDEWEB)

In the last two years, rapid progress has been made in the energy conversion efficiencies of GaAs solar cells fabricated from molecular beam epitaxy (MBE) material. The efficiencies of cells fabricated from MBE material are now comparable with those fabricated from metal-organic chemical vapor deposition material, even for cells of dimension 2 cmx4 cm. This paper reviews the progress in MBE cell efficiencies. Also discussed is the role oval defects play in GaAs diode and solar cell performance. (orig.).

1991-05-01

436

Review of recent proteomic applications in aquatic toxicology  

British Library Electronic Table of Contents (United Kingdom)

Abstract Over the last decade, the environmental sciences have witnessed an incredible movement towards the utilization of high-throughput molecular tools that are capable of detecting simultaneous changes of hundreds, and even thousands, of molecules and molecular components after exposure of organisms to different environmental stressors. These techniques have received a great deal of attention because they not only offer the potential to unravel novel mechanisms of physiological and toxic action but are also amenable to the discovery of biomarkers of exposure and effects. In this article, we review the state of knowledge of one of these tools in ecotoxicological research: proteomics. We summarize the state of proteomics research in fish, and follow with studies conducted with aquatic in...

2011-01-01

437

Recycling of PTFE by means of ionizing rays  

International Nuclear Information System (INIS)

By treatment with beta or gamma rays, PTFE waste is converted to high-grade PTFE fine powder. High-molecular weight PTFE is degraded to low-molecular weight PTFE. Due to this the density, the degree of crystallinity, and the melt flow index are increased, which enhances the brittleness of the material. Irradiation of PTFE thus facilitates milling and makes the material pourable and free-flowing. Milled PTFE fine powder, lie PTFE plastic, combines temperature resistance, weather fastness, and chemical stability with good slip behaviour and antiadhesive properties. Areas of application for fine powder include additives for plastics, printing inks, nonstick coatings, and antifriction lacquers. (orig.).

1994-01-01

438

Production of Group IIA atomic and molecular negative ion beams in a cesium-sputter negative ion source  

Energy Technology Data Exchange (ETDEWEB)

The results of an investigation on the production of Group IIA atomic and molecular negative ion beams formed in a cesium-sputter negative ion source are presented. The sputtering material was formed by pressing pellets of stoichiometric mixtures of the Group IIA element carbonates and 10% copper powder. Negative ions of several alkaline-earth elements and their oxides have been observed. Beam intensities as high as 180 pA have been observed for Sr{sup -}and 20 nA for SrO{sup -}. (orig.).

1996-09-11

439

Production of Group IIA atomic and molecular negative ion beams in a cesium-sputter negative ion source  

International Nuclear Information System (INIS)

The results of an investigation on the production of Group IIA atomic and molecular negative ion beams formed in a cesium-sputter negative ion source are presented. The sputtering material was formed by pressing pellets of stoichiometric mixtures of the Group IIA element carbonates and 10% copper powder. Negative ions of several alkaline-earth elements and their oxides have been observed. Beam intensities as high as 180 pA have been observed for Sr"-and 20 nA for SrO"-. (orig.).

1996-09-01

440

Molecular models in the quantum-chemical investigation of the structure of defect centers on oxide catalysts  

Energy Technology Data Exchange (ETDEWEB)

Several possibilities of the use of molecular models in quantum-chemical investigations of the structure of defect centers on the surfaces of oxides on nontransition elements have been illustrated. There has been a special discussion of the assumption of the local nature of the chemical interactions in these systems, which underlies such an approach, and of the consequent laws governing the formation of their lattices in the example cases of zeolites, kaolinites, and comparable boron- and aluminum-containing oxides. A quantum-chemical interpretation of the body of experimental data from investigations of the dehydroxylation of H forms of zeolites has been given. The structure of the Lewis acid centers formed as a result, and their chemisorption properties, have been discussed.

1987-05-01

441

Molecular dynamics study of reaction kinetics in viscous media  

British Library Electronic Table of Contents (United Kingdom)

Predicted by stochastic models and observed experimentally in a number of isomerization reactions, viscosity-induced solvent effects manifest themselves in a significant departure of the reaction rates from the values expected on the basis of transition state theory. These effects are well understood within the framework of stochastic models; however, the predictive power of such models is limited by the fact that their parameters are not readily available. Experiment and molecular dynamics (MD) simulations can provide such information and can serve as the testing grounds for various stochastic models. In real solvents, a change in viscosity is inevitably associated with variation of at least one of the three factors - temperature, pressure, or solvent identity, resulting in different solv...

2011-01-01

442

Molecular accessibility in solvent swelled coal. Quarterly report  

Energy Technology Data Exchange (ETDEWEB)

To expand the information base on molecular accessibility in solvent swelled coal, Argonne Premium Coal Samples (APCS) were swelled in polar, basic solvents before and after moisture loss and upon air oxidation. So far studies have been reported on the changes in pore size distribution as a function of temperature when polar basic swelling solvents are used. Additional studies employing EPR spin probe techniques performed on the breaking up of the hydrogen bonding between bedding planes were later confirmed by magnetic resonance imaging at Argonne National Lab and the University of Illinois.

1992-11-01

443

Inorganic molecular sieves: Preparation, modification and industrial application in catalytic processes  

British Library Electronic Table of Contents (United Kingdom)

The increasing environmental concern and promotion of ''green processes'' are forcing the substitution of traditional acid and base homogeneous catalysts by solid ones. Among these heterogeneous catalysts, zeolites and zeotypes can be considered as real ''green'' catalysts, due to their benign nature from an environmental point of view. The importance of these inorganic molecular sieves within the field of heterogeneous catalysis relies not only on their microporous structure and the related shape selectivity, but also on the flexibility of their chemical composition. Modification of the zeolite framework composition results in materials with acidic, basic or redox properties, whereas multifunctional catalysts can be obtained by introducing metals by ion exchange or impregnation procedures...

2011-01-01

444

Influence of wood extractives in the polymerization of methyl methacrylate by gamma irradiation  

International Nuclear Information System (INIS)

Those materials that can be extracted from pine or oak by ether, ethanol, methyl methacrylate (MMA), or benzene--alcohol all act as inhibitors in the #gamma# polymerization of MMA--wood composites. It was found that preirradiation of either the wood or of the wood--monomer combination reduces or eliminates the inhibitory effect. The most practical industrial solution to this problem is to increase the dose, thereby achieving high molecular polymer in the composite. However, the presence of a maximum in the molecular weight--dose curves means that each wood--monomer pair may have a different optimum dose.

1975-01-01

445

High-optical-quality GaInP and GaInP/AlInP double heterostructure lasers grown on GaAs substrates by gas-source molecular-beam epitaxy  

Science.gov (United States)

By gas-source molecular-beam epitaxy, we obtained a device-quality GaInP epitaxial layer lattice matched to (100)-GaAs substrates, with a photoluminescence efficiency comparable to that of a crystal grown by liquid-phase epitaxy. A GaInP/AlInP double heterostructure laser with a GaInP active layer was fabricated, and pulsed lasing operation was achieved at room temperature for, we believe, the first time.

1989-11-01

446

Description of alkane and benzene halogen derivatives adsorption on graphitized thermal carbon black based on the model of ideal two-dimensional gas  

International Nuclear Information System (INIS)

By comparison of standard entropies theoretically calculated and determined from gas-chromatographic data for 40 halo-aliphatic and halo-aromatic compounds 8 organic iodine compounds among them, adsorbed on graphitized thermal carbon black it was found that in all the cases the molecular model of ideal two-dimensional gas is a sufficiently good approximation. It was shown that for a number of systems the agreement can be improved if the vibrations of the center of molecular mass relative to the surface are taken into account

447

Application of electro-Fenton oxidation for the detoxification of olive mill wastewater phenolic compounds  

Energy Technology Data Exchange (ETDEWEB)

Olive mill effluent (OMW) is an example of a wastewaters containing high concentrations of recalcitrant and toxic compounds which are polyphenolics of different molecular weight. It causes disposal problems because they contain powerful pollutants. Treatment and detoxification of phenolic fraction extracted from olive mill wastewaters as well as a synthetic phenolic mixture was investigated by electro-Fenton method. Results shows that this method is highly efficient in polymerising low molecular mass phenolics and removing a large amount of recalcitrant polyphenolic compounds. This treatment decreased 78% of the toxicity which sustained a good anaerobic post-treatment. (orig.)

2003-07-01

448

Metabolic relationships between monogalactosyldiacylglycerol and digalactosyldiacylglycerol molecular species in Dunaliella salina  

Energy Technology Data Exchange (ETDEWEB)

Dunaliella salina cells were pulse-labeled for 2 min with (/sup 14/C)palmitic acid, (/sup 14/C)oleic acid, or (/sup 14/C)lauric acid in order to trace the pathway of galactolipid biosynthesis and desaturation. Through the use of high performance liquid chromatography it was possible to follow the movement of radioactivity through many individual molecular species of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) for periods of 24 h and, in some cases, as much as 120 h. Analysis of the fatty acid fluxes permitted us to refine current views regarding biosynthesis of the predominantly prokaryotic galactolipids. The initial D. salina MGDG molecular species, containing paired oleate and palmitate (18:1/16:0), can follow two metabolic routes. If the palmitoyl chain is desaturated to 16:1, the resulting 18:1/16:1 MGDG is subject to rapid further desaturation to varying degrees, and a part of these products is subsequently ...

1987-06-05

449

Functional and physical molecular size of the chicken hepatic lectin determined by radiation inactivation and sedimentation equilibrium analysis  

Energy Technology Data Exchange (ETDEWEB)

Radiation inactivation and sedimentation equilibrium analysis were used to determine the functional and physical size of the chicken hepatic membrane receptor that binds N-acetylglucosamine-terminated glycoproteins. Purified plasma membranes from chicken liver were irradiated with high energy electrons and assayed for 125I-agalactoorosomucoid binding. Increasing the dose of ionizing radiation resulted in a monoexponential decay in binding activity due to a progressive loss of binding sites. The molecular mass of the chicken lectin, determined in situ by target analysis, was 69,000 +/- 9,000 Da. When the same irradiated membranes were solubilized in Brij 58 and assayed, the binding protein exhibited a target size of 62,000 +/- 4,000 Da; in Triton X-100, the functional size of the receptor was 85,000 +/- 10,000 Da. Sedimentation equilibrium measurements of the purified binding protein yielded a lower limit molecular weight of 79,000 +/- 7,000. ...

1990-03-05

450

Development of methods of forecasting properties of polymer packaging materials which do not cause any changes in medicinal preparations during sterilization  

International Nuclear Information System (INIS)

The authors present the results of an investigation of the effect of gamma radiation on the properties of low-molecular moulded polymethyl methacrylates (molecular weight distribution, physico-mechanical properties, resistance to the effects of aqueous media and physiological solution) in the form of copolymers of methyl methacrylate with methyl acrylate (MA) or butyl acrylate (BA) with the brand names Dacryl-4B, Dacryl-2M and Dacryl-4M (4% BA; 2 and 4% MA respectively) having a molecular weight of around 10"5. For comparison, block polymethyl methacrylate with a molecular weight of 3 x 10"6 was used. The results of experiments on the ageing of unirradiated and irradiated specimens in a heated store-room (t = 10 - 20"0C) and at high temperatures (90"0C) are also given. It is shown that irradiation with doses of 2.5 - 20 Mrad leads to radiolysis of the above copolymers, accompanied by destructive ...

1974-12-09

451

Development of methods for forecasting properties of polymer packaging materials which do not cause any change in medicinal preparation during their sterilization  

International Nuclear Information System (INIS)

The authors present the results of an investigation of the effect of gamma radiation on the properties of low-molecular moulded polymethyl methacrylates (molecular weight distribution, physicomechanical properties, resistance to the effects of aqueous media and physiological solution) in the form of copolymers of methyl methacrylate with methyl (MA) or butyl acrylate (BA) with the brand names Dacryl-4B, Dacryl-2M and Dacryl-4M (4% BA; 2 and 4% MA respectively) having a molecular weight of around 10"5. For comparison, block polymethyl methacrylate with a molecular weight of 3 x 10"6 was used. The results of experiments on the ageing of unirradiated and irradiated specimens in a heated store-room (t = 10 - 20"0C) and at high temperatures (90"0C) are also given. It is shown that irradiation with doses of 2.5-20 Mrad leads to radiolysis of the above copolymers, accompanied by destructive processes. Evidence ...

1975-01-01

452

FABRICATION OF BISMUTH NANOWIRE DEVICES USING FOCUSED ION BEAM MILLING  

International Nuclear Information System (INIS)

In this work, a focused ion beam (FIB) milling process has been developed to fabricate 50 nm Bi nanowire and transistor structures using FEI-200 dual beam FIB system. For the fabrication, 50 nm bismuth film was thermally evaporated through EBL patterned PMMA windows onto SiO_2 substrates with pre-defined contact pads. Bi nanowire widths ranging from 30 nm to 100 nm have been successfully fabricated by milling out unwanted areas using 30 KeV Ga+ ion beam. A single-pixel-line ion beam blanking technique has been utilised to fabricate Bi nanowire as small as 30 nm in diameter and few micrometers long. In order to form good ohmic contacts for sub 50 nm bismuth nanowires, a drill-and-fill process has been developed using FIB to sputter away the surface oxide of bismuth after the in-situ platinum nanowire contacts deposition. To our knowledge, this is the first time a focused ion beam process has been used to fabricate bismuth nanowire. The fabricated Bi nanowires were ...

2009-07-23

453

Quantum and semiclassical spin networks: from atomic and molecular physics to quantum computing and gravity  

Energy Technology Data Exchange (ETDEWEB)

The mathematical apparatus of quantum-mechanical angular momentum (re)coupling, developed originally to describe spectroscopic phenomena in atomic, molecular, optical and nuclear physics, is embedded in modern algebraic settings which emphasize the underlying combinatorial aspects. SU(2) recoupling theory, involving Wigner's 3nj symbols, as well as the related problems of their calculations, general properties, asymptotic limits for large entries, nowadays plays a prominent role also in quantum gravity and quantum computing applications. We refer to the ingredients of this theory-and of its extension to other Lie and quantum groups-by using the collective term of 'spin networks'. Recent progress is recorded about the already established connections with the mathematical theory of discrete orthogonal polynomials (the so-called Askey scheme), providing powerful tools based on asymptotic expansions, which correspond on the physical side to ...

2008-11-15

454

Molecular-beam/surface-science apparatus for state-resolved chemisorption studies using pulsed-laser preparation  

International Nuclear Information System (INIS)

We describe a new apparatus that combines pulsed laser excitation in a molecular beam with surface-science methods for preparation of clean single-crystal surfaces and detection of adsorbates to enable state-selected studies of gas-surface reaction dynamics. Reactant molecules are prepared in specific vibrationally excited states via overtone pumping using tunable, narrow-band laser radiation. The collision-free environment of the molecular beam prevents relaxation of the prepared molecules before impact on the target surface and enables complete control over the collision energy and incidence angle. Chemisorption products are detected after a given deposition time by Auger electron spectroscopy. To achieve sufficient beam flux of state-selected reactant molecules for product detection by standard surface-science techniques, we use a high-intensity, short-pulse molecular-beam source matched to the low duty cycle of the ...

2003-09-01

455

Investigating the formation mechanism of soot-like materials present in blast furnace coke samples  

Science.gov (United States)

An attempt to gain an understanding of the formation mechanism of these 'soot-like' materials has been made by means of tracing the changes in the molecular-mass distribution and molecular structure of the NMP-extractable materials from an injectant coal as well as its partially gasified chars and its pyrolytic tars. Variations in the SEC chromatograms provide clues about changes in the apparent molecular-mass distributions of these NMP extracts. Results suggest that the build-up of 'soot-like' materials follows from the secondary reactions of tars evolved from the injectant coal. The likely secondary-reaction pathways have been probed by collating structural information on these NMP extracts. The time-resolved 13-16 and 22-25 min elution fractions from the SEC column have been characterized using UV fluorescence (UV F) spectroscopy. Greater concentrations of larger aromatic ring systems ...

2008-09-15

456

EXTREMELY LARGE AND HOT MULTILAYER KEPLERIAN DISK AROUND THE O-TYPE PROTOSTAR W51N: THE PRECURSORS OF THE HCH II REGIONS?  

International Nuclear Information System (INIS)

We present sensitive high angular resolution (0.''57-0.''78) SO, SO_2, CO, C_2H_5OH, HC_3N, and HCOCH_2OH line observations at millimeter and submillimeter wavelengths of the young O-type protostar W51 North made with the Submillimeter Array. We report the presence of a large (about 8000 AU) and hot molecular circumstellar disk around this object, which connects the inner dusty disk with the molecular ring or toroid reported recently and confirms the existence of a single bipolar outflow emanating from this object. The molecular emission from the large disk is observed in layers with the transitions characterized by high excitation temperatures in their lower energy states (up to 1512 K) being concentrated closer to the central massive protostar. The molecular emission from those transitions with low or moderate excitation temperatures is found in the outermost parts of the disk and exhibits an inner ...

2010-12-10

457

Topological and thermodynamic investigations of molecular interactions of aniline and o-toluidine with chloroform  

Energy Technology Data Exchange (ETDEWEB)

Molar excess volumes, V{sup E}, molar excess enthalpies, H{sup E}, and speeds of sound data, u, of chloroform (i) + aniline or o-toluidine (j) binary mixtures have been measured as a function of composition at 308.15 K. Isentropic compressibility changes of mixing, {kappa}{sub S}{sup E} have been determined by employing speed of sound data. Topological investigations of V{sup E} data reveals that aniline, chloroform and o-toluidine are associated entities and these (i + j) mixtures contain a 1:1 molecular complex. The IR studies lend further support to the nature and extent of interaction for the proposed molecular entity in the mixtures. H{sup E} and {kappa}{sub S}{sup E} values have also been calculated by employing Moelwyn-Huggins concept [Polymer 12 (1971) 387] taking topology of the constituents of the mixtures. It has been observed that calculated H{sup E} and {kappa}{sub S}{sup E} values compare well with their corresponding experimental ...

2008-05-30

458

Topological and thermodynamic investigations of molecular interactions of aniline and o-toluidine with chloroform  

International Nuclear Information System (INIS)

Molar excess volumes, VE, molar excess enthalpies, HE, and speeds of sound data, u, of chloroform (i) + aniline or o-toluidine (j) binary mixtures have been measured as a function of composition at 308.15 K. Isentropic compressibility changes of mixing, ?SE have been determined by employing speed of sound data. Topological investigations of VE data reveals that aniline, chloroform and o-toluidine are associated entities and these (i + j) mixtures contain a 1:1 molecular complex. The IR studies lend further support to the nature and extent of interaction for the proposed molecular entity in the mixtures. HE and ?SE values have also been calculated by employing Moelwyn-Huggins concept [Polymer 12 (1971) 387] taking topology of the constituents of the mixtures. It has been observed that calculated HE and ?SE values compare well with their corresponding experimental values. The observed VE, HE and ?SE data have also been analyzed in terms of Flory ...

2008-05-30

459

Theoretical study of asymmetric molecular-frame photoelectron angular distributions for C 1s photoejection from CO2  

Energy Technology Data Exchange (ETDEWEB)

We report the results of ab initio calculations of cross sections and molecular-frame photoelectron angular distributions for C 1s ionization of CO2, and propose a mechanism for the recently observed asymmetry of those angular distributions with respect to the CO^+and O^+ions produced by subsequent Auger decay. The fixed-nuclei, photoionization amplitudes were constructed using variationally obtained electron-molecular ion scattering wave functions. We have also carried out electronic structure calculations which identify a dissociative state of the CO2^++ dication that is likely populated following Auger decay and which leads to O^+ + CO^+ fragment ions. We show that a proper accounting of vibrational motion in the computation of the photoelectron angular distributions, along with reasonable assumptions about the nuclear dissociation dynamics, gives results in good agreement with recent experimental observations. We also demonstrate that ...

2009-02-18

460

The response of quartz crystals coated with thin fatty acid film to organic gases  

Energy Technology Data Exchange (ETDEWEB)

We tried to apply a quartz crystal as a sensor by using the resonant frequency and the resistance properties of quartz crystals. Four kinds of fatty acids that have the same head groups were coated on the surfaces of the quartz crystals, and the shift of the resonant frequency and the resistance were observed based on the lengths of the tail groups. Myristic acid (C{sub 14}), palmitic acid (C{sub 16}), stearic acid (C{sub 18}), and arachidic acid (C{sub 20}) were deposited on the surfaces of quartz crystals by using the Langmuir-Blodgett (LB) method. As a result, the resonant frequency change was more sensitive to high molecular-weight fatty acids than to low molecular-weight ones. We also observed the effect of temperature on stearic acid LB films, and the response properties of quartz crystals coated with stearic-acid LB films to organic gases were investigated. As a result, the sensitivity of quartz crystals to organic gases was higher for ...

1999-07-01

461

The Local Environment of the FUor-like Objects AR 6A and 6B  

CERN Document Server

We present new 12CO J=3-2 and HCN J=3-2 molecular line maps of the region surrounding the young star AR 6 using the 15 metre James Clerk Maxwell Telescope. AR 6 was previously found to be a double source with both components exhibiting several characteristics of FU Orionis (FUor) eruptive variable stars. Our data indicates that AR 6, like FU Orionis itself, does not possess a CO outflow and likewise, does not show evidence for large amounts of molecular g as in its circumstellar environment. We conclude that from the near-IR to the sub-mm, AR 6 is similar to FU Orionis in several respects. We interpret the lack of significant dust and molecular gas in the circumstellar environment of AR 6, together with the large near-IR thermal excess, as evidence that the sources have exhausted their natal envelopes, that they have at least small hot circumstellar disks, and that they are more evolved than Class I protostars. This, in ...

2008-01-01

462

Studies about the separation of molecular species of hydrogen's isotopes by cryogenic distillation in a plant for heavy water detritiation  

Energy Technology Data Exchange (ETDEWEB)

Cryogenic distillation is the main industrial method for separating hydrogen's isotopes, because it presents the advantage of high separating factors and also the possibility of processing great quantities of gases. In the case of multicomponent mixtures the determination of transport for molecular species between the two phases is very difficult owing to the particularities of physical characteristics of each component from the mixture. The transport of molecular species is also strongly influenced by the hydrodynamics of two phases, in strong connection with the dimension of the interface between the vapor and liquid phase. The characteristics of the interface depend on the type and geometry of the separation area: plates or package. The traditional methods of analysis for exchange processes use the concept 'theoretic plate', a physical entity for which the values of concentrations for vapors and liquid that leaves ...

1998-07-01

463

Simulating fullerene ball bearings of ultra-low friction  

Energy Technology Data Exchange (ETDEWEB)

We report the direct molecular dynamics simulations for molecular ball bearings composed of fullerene molecules (C{sub 60} and C{sub 20}) and multi-walled carbon nanotubes. The comparison of friction levels indicates that fullerene ball bearings have extremely low friction (with minimal frictional forces of 5.283 x 10{sup -7} and 6.768 x 10{sup -7} nN/atom for C{sub 60} and C{sub 20} bearings) and energy dissipation (lowest dissipation per cycle of 0.013 and 0.016 meV/atom for C{sub 60} and C{sub 20} bearings). A single fullerene inside the ball bearings exhibits various motion statuses of mixed translation and rotation. The influences of the shaft's distortion on the long-ranged potential energy and normal force are discussed. The phonic dissipation mechanism leads to a non-monotonic function between the friction and the load rate for the molecular bearings.

2007-03-21

464

Quantum computing using molecular electronic and vibrational states  

Energy Technology Data Exchange (ETDEWEB)

We numerically constructed elementary phase-correct global quantum gates by using molecular electronic and vibrational states to encode two qubits and implement the Deutsch-Jozsa algorithm. The calculations were based on optimal control theory (OCT). The molecular species we chose were Na{sub 2} and Li{sub 2}. The electronic X{sup 1}{sigma}{sub g}{sup +} and A{sup 1}{sigma}{sub u}{sup +} states were taken as two orthonormalized energy levels of the electronic qubit. The vibrational qubits were those involved in these electronic states. The time duration of the optimized pulses with high fidelity was typically 500-900 fs, which reflects the wavepacket dynamics in electronically ground and excited states. When implementing the Deutsch-Jozsa algorithm by combining these elementary gates, we obtained a maximum probability 83.12% for Li{sub 2} molecule, which indicates that the electronic-vibrational qubits are worse than the vibrational-vibrational ...

2008-01-22

465

Double-Edge Molecular Measurement of Lidar Wind Profiles in the VALID Campaign  

Science.gov (United States)

We have developed a transportable container based direct detection Doppler lidar based on the double-edge molecular technique. The pulsed solid state system was built at the University of Geneva. It was used to make range resolved measurements of the atmospheric wind field as part of the VALID campaign at the Observatoire de Haute Provence in Provence, France in July 1999. Comparison of our lidar wind measurements, which were analyzed without knowledge of the results of rawinsonde measurements made under the supervision of ESA, show good agreement with these rawinsondes. These are the first Doppler lidar field measurements made with an eyesafe direct detection molecular-based system at 355 nm and serve as a demonstrator for future spaceborne direct detection wind systems such as the Atmospheric Dynamics mission. Winds are an important contributor to sea surface temperature measurements made with the Tropical Rainfall Measuring Mission (TRMM) ...

2000-01-01

466

Cosmic evolution of the atomic and molecular gas content of galaxies  

CERN Document Server

We study the evolution of the cold gas content of galaxies by splitting the interstellar medium into its atomic and molecular hydrogen components, using the galaxy formation model GALFORM in the LCDM framework. We calculate the molecular-to-atomic hydrogen mass ratio, H2/HI, in each galaxy using two different approaches; the pressure-based empirical relation of Blitz & Rosolowsky and the theoretical model of Krumholz, McKeee & Tumlinson, and apply them to consistently calculate the star formation rates of galaxies. We find that the model based on the Blitz & Rosolowsky law predicts an HI mass function, CO(1-0) luminosity function, correlations between the H2/HI ratio and stellar and cold gas mass, and infrared-CO luminosity relation in good agreement with local and high redshift observations. The HI mass function evolves weakly with redshift, with the number density of high mass galaxies decreasing with increasing redshift. In the ...

2011-01-01

467

Coal structure construction system with construction knowledge and partial energy evaluation; Kochiku chishiki to bubunteki energy hyoka ni yoru sekitan bunshi kozo kochiku system  

Energy Technology Data Exchange (ETDEWEB)

The computer aided coal structure construction system is proposed, and a computational construction example is presented. The coal structure construction engine of this system fabricates molecular structure by connecting fragments sequentially inputted through a user interface. The best structure candidate is determined using construction knowledge and partial energy evaluation every addition of one fragment, and this process is subsequently repeated. The structure evaluation engine analyzes the 3-D conformation candidate by molecular dynamics, and evaluates the conformation by determining the energy value of an optimum structure. As an example, this system was applied to construction of coal molecular structure based on the actual data of partial structure composed of 26 structures from 2l kinds of aromatic cluster structures, 27 bonds from 2 kinds of bridged bonds, and 16 groups from 2 kinds of terminal substitutional ...

1996-10-28

468

CdS and ZnS quantum dots embedded in hyaluronic acid films  

Energy Technology Data Exchange (ETDEWEB)

An in situ synthesis of ZnS and CdS quantum dots (QDs) in an aqueous solution of sodium hyaluronate (Hyal) produced foils emitting light on excitation with a UV light. The wavelength of emission was only slightly QDs size and more QDs concentration dependent and reached up to {approx}320 nm in the case of ZnS and {approx}400-450 nm in the case of CdS. Nanoparticles remained as non-agglomerated 10-20 nm nanoclusters. CdS/Hyal and ZnS/Hyal-QDs biocomposites were characterized using photoluminescence (PL), IR spectrometric techniques, and Transmission Electron Microscopy (TEM). The absolute molecular weights, radii of gyration, R{sub g}, and thermodynamic properties of the obtained foils are given. Electric resistivity studies performed for the hyaluronic foil in the 100-1000 V range have revealed that the hyaluronate foil has very weak conducting properties and QDs only insignificantly affect those properties as QDs practically did not interact with the foil. Size ...

2009-07-29

469

All-atom molecular dynamics simulations using orientational constraints from anisotropic NMR samples  

Science.gov (United States)

Orientational constraints obtained from solid state NMR experiments on anisotropic samples are used here in molecular dynamics (MD) simulations for determining the structure and dynamics of several different membrane-bound molecules. The new MD technique is based on the inclusion of orientation dependent pseudo-forces in the COSMOS-NMR force field. These forces drive molecular rotations and re-orientations in the simulation, such that the motional time-averages of the tensorial NMR properties approach the experimentally measured parameters. The orientational-constraint-driven MD simulations are universally applicable to all NMR interaction tensors, such as chemical shifts, dipolar couplings and quadrupolar interactions. The strategy does not depend on the initial choice of coordinates, and is in principle suitable for any flexible molecule. To test the method on three systems of increasing complexity, we used as constraints some deuterium ...

2007-03-03

470

All-atom molecular dynamics simulations using orientational constraints from anisotropic NMR samples  

Energy Technology Data Exchange (ETDEWEB)

Orientational constraints obtained from solid state NMR experiments on anisotropic samples are used here in molecular dynamics (MD) simulations for determining the structure and dynamics of several different membrane-bound molecules. The new MD technique is based on the inclusion of orientation dependent pseudo-forces in the COSMOS-NMR force field. These forces drive molecular rotations and re-orientations in the simulation, such that the motional time-averages of the tensorial NMR properties approach the experimentally measured parameters. The orientational-constraint-driven MD simulations are universally applicable to all NMR interaction tensors, such as chemical shifts, dipolar couplings and quadrupolar interactions. The strategy does not depend on the initial choice of coordinates, and is in principle suitable for any flexible molecule. To test the method on three systems of increasing complexity, we used as constraints some deuterium ...

2007-05-15

471

All-atom molecular dynamics simulations using orientational constraints from anisotropic NMR samples  

International Nuclear Information System (INIS)

Orientational constraints obtained from solid state NMR experiments on anisotropic samples are used here in molecular dynamics (MD) simulations for determining the structure and dynamics of several different membrane-bound molecules. The new MD technique is based on the inclusion of orientation dependent pseudo-forces in the COSMOS-NMR force field. These forces drive molecular rotations and re-orientations in the simulation, such that the motional time-averages of the tensorial NMR properties approach the experimentally measured parameters. The orientational-constraint-driven MD simulations are universally applicable to all NMR interaction tensors, such as chemical shifts, dipolar couplings and quadrupolar interactions. The strategy does not depend on the initial choice of coordinates, and is in principle suitable for any flexible molecule. To test the method on three systems of increasing complexity, we used as constraints some deuterium ...

2007-05-01

472

Transforming Growth Factor-b Induces Differentiation of the Labyrinthine Trophoblast Stem Cell Line SM10  

British Library Electronic Table of Contents (United Kingdom)

The mammalian placenta consists of different trophoblast cell types that assist in the variety of functions required for the maintenance of pregnancy. In rodents, labyrinthine trophoblasts of the placenta are especially important, because they are capable of differentiating into fused labyrinthine cells, which form the feto-maternal exchange surface. Even though the molecular signals triggering labyrinthine trophoblast differentiation are poorly understood, transforming growth factor-b (TGF-b) has been shown to be present in the placental environment and alter trophoblast development. In this study, we investigated the effects of TGF-b on the differentiation of the labyrinthine trophoblast stem cell lines SM10 and HRP-1. RT-PCR analyses demonstrated that while the molecular expression of l...

2005-01-01

473

Torsional responses of double-walled carbon nanotubes via molecular dynamics simulations  

Energy Technology Data Exchange (ETDEWEB)

The buckling behaviors of double-walled carbon nanotubes (DWCNTs) under torsion are investigated by using molecular dynamics (MD) simulations. The effect of length on the torsional buckling behaviors of DWCNTs is examined for the first time. The simulation results show that the DWCNTs experience gradual or simultaneous buckling deformations depending on their lengths. In addition, the effect of the inner tube in a DWCNT on its torsional buckling behavior is also examined. The presence of the inner tube triggers van der Waals (vdW) interactions between it and the outer tube and thus leads to a stiffening effect of the DWCNT against torsional deformation. Whether the ends of the inner tube are free or fixed and whether it is subject to a torque or not, the critical torque and the critical torsional angle of the outer tube are only marginally affected.

2008-11-12

474

Topological investigations of molecular interactions in mixtures containing alkanols: molar excess volumes and molar excess enthalpies  

International Nuclear Information System (INIS)

Molar excess volumes, VE and molar excess enthalpies, HE of 1,3-dioxolane (D) (i) + propan-1-ol, 1,3-dioxolane (i) + butan-1-ol and 1,3-dioxolane (i) + butan-2-ol (j) binary mixtures have been measured as a function of composition at 308.15 K. The analysis of VE data by graph, theoretical approach reveals that while propan-1-ol, butan-1-ol exist as associated entities in the pure state; 1,3-dioxolane and butanol exist as monomers in their pure state. These (i+j) binary mixtures are characterized by interactions between ethereal oxygen atom of D(i) and hydrogen atom of alkanols. The IR studies lend additional support to the proposed structure of molecular entitles in these mixtures. The energetics of the mixtures have also been studied.

2004-04-08

475

The structure of molecular clouds - III. A link between cloud structure and star formation mode  

British Library Electronic Table of Contents (United Kingdom)

Abstract We analyse extinction maps of nearby giant molecular clouds to forge a link between driving processes of turbulence and modes of star formation. Our investigation focuses on cloud structure in the column density range above the self-shielding threshold of 1-mag AV and below the star formation threshold - the regime in which turbulence is expected to dominate. We identify clouds with shallow mass distributions as cluster forming. Clouds that form stars in a less clustered or isolated mode show a steeper mass distribution. Structure functions prove inadequate to distinguish between clouds of different star formation mode. They may, however, suggest that the turbulence in the average cloud is governed by solenoidal forcing. The same is found using the -variance analysis which also in...

2011-01-01

476

Structure, mechanical properties, and dynamic fracture in nanophase silicon nitride via parallel molecular dynamics  

Energy Technology Data Exchange (ETDEWEB)

Million-atom molecular-dynamics (MD) simulations are performed to study the structure, mechanical properties, and dynamic fracture in nanophase Si{sub 3}N{sub 4}. The authors find that intercluster regions are highly disordered: 50% of Si atoms in intercluster regions are three-fold coordinated. Elastic moduli of nanophase Si{sub 3}N{sub 4} as a function of grain size and porosity are well described by a multiphase model for heterogeneous materials. The study of fracture in the nanophase Si{sub 3}N{sub 4} reveals that the system can sustain an order-of-magnitude larger external load than crystalline Si{sub 3}N{sub 4}. This is due to branching and pinning of the crack front by nanoscale microstructures.

1997-09-01

477

Stochastic kinetics of ribosomes: single motor properties and collective behavior  

CERN Document Server

Synthesis of protein molecules in a cell are carried out by ribosomes. A ribosome can be regarded as a molecular motor which utilizes the input chemical energy to move on a messenger RNA (mRNA) track that also serves as a template for the polymerization of the corresponding protein. The forward movement, however, is characterized by an alternating sequence of translocation and pause. Using a quantitative model, which captures the mechanochemical cycle of an individual ribosome, we derive an {\\it exact} analytical expression for the distribution of its dwell times at the successive positions on the mRNA track. Inverse of the average dwell time satisfies a ``Michaelis-Menten-like'' equation and is consistent with the general formula for the average velocity of a molecular motor with an unbranched mechano-chemical cycle. Extending this formula appropriately, we also derive the exact force-velocity relation for a ribosome. Often many ribosomes ...

2009-01-01

478

Species in the genus Turritopsis (Cnidaria, Hydrozoa): a molecular evaluation:  

British Library Electronic Table of Contents (United Kingdom)

Abstract Mitochondrial ribosomal gene sequences were used to investigate the status of several populations of hydromedusae belonging to the genus Turritopsis (family Oceaniidae). Several nominal species have been described for this genus, but most of them had been synonymized and attributed to one cosmopolitan species, Turritopsis nutricula. A recent revision based on morphological and reproductive characters, however, has shown that many different populations can be distinguished and that several of the nominal Turritopsis species are likely valid biological species. Our investigation using molecular sequence data of 16S mitochondrial gene confirms these results. The Mediterranean Turritopsis must be attributed to Turritopsis dohrnii and the Turritopsis of New Zealand must be referred to ...

2007-01-01

479

Potentially pathogenic free-living amoebae isolated from hospital wards with immunodeficient patients in Tehran, Iran  

British Library Electronic Table of Contents (United Kingdom)

This study investigated the occurrence of free-living amoebae (FLA) in immunodeficiency wards of hospitals in Tehran, Iran. A total of 70 dust and biofilm samples from wards serving transplant, pediatric (malignancies), HIV, leukemia and oncology patients of five university hospitals were collected and examined for the presence of FLA using culturing and molecular approaches. Based on the morphology of the amoebae in plate cultures, primer sets were applied for molecular identification of Acanthamoeba, vahlkampfiid amoebae and Hartmannella. Out of 70 samples, 37 (52.9%) were positive for FLA. Acanthamoeba belonged to the T4 genotype was the most prevalent isolate. Presence of the T4 genotype on medical instruments, including an oxygen mask in an isolation room of an immunodeficiency pediat...

2011-01-01

480

NAME=\\  

Wastenet

...the School, the research group structure was recently revised and now comprises the following teams: Drug Design and Analysis Pharmaceutics Pharmacy Practice and Policy Pharmacological and Biomedical Science The current structure was designed to take into account the future development of research in the academic area. The ...Discovery, Molecular Modelling, Pharmacology and Molecular Biology) and international recognition (Biological Sciences), which have now been re-organised into the Drug Design and Analysis and Pharmacological and Biomedical Sciences teams. The reorganisation also aimed to improve the research reputation of the other teams. The improvements in ... Email to a friend Print Within this area Drug design and analysis Pharmaceutics Pharmacy practice and policy Pharmacological and biomedical sciences Projects Publications Staff Considering a course? Research Degrees Course Finder Order a Prospectus Subject Areas Sunderland Facts ...

481

Morphologie des cellules de levure et la reproduction sexuelle - Apercu general et quelques considerations  

British Library Electronic Table of Contents (United Kingdom)

Over the decades, basic research in life sciences has profited greatly from the study of the small unicellular fungal species Saccharomyces cerevisiae. This yeast turned out to be key for the identification and understanding of molecular mechanisms that underlay the basic functions of all eukaryotic cells. These include, but are not limited to, the regulatory mechanisms behind cellular reproduction (cell cycle control), cellular morphogenesis (cell polarity, cytoskeleton and membrane trafficking) and the management of cellular information (chromosome biology, transcription and translation). Rapid access to genomic information of many yeast species, combined with bioinformatics analyses, provide information on the evolutionary history of yeasts and the molecular ancestry of their constituen...

2011-01-01

482

Molten glass corrosion resistance of immersed combustion-heating tube materials in E-glass  

International Nuclear Information System (INIS)

The corrosion resistance of molybdenum, molybdenum disilicide, and a SiC_(_p_)/Al_2O_3 composite to molten E-glass at 1,550 C was studied. Mo showed no tendency to oxidize as it was immersed in soda-lime silicate glass in a parallel study. MoSi_2 was corroded by soluble molecular oxygen, leaving a Mo_5Si_3 interface behind. The SiC_(_p_)/Al_2O_3 composite was corroded at a more rapid rate wherein the SiC component was oxidized to form amorphous silica and CO bubbles. Based on these results, the activity of soluble molecular oxygen in E-glass was determined to be in the range of 2.4 x 10"-"1"4 to 2.0 x 10 "-"8.

483

Molecular structure of platinum(III) hydroxoacetates according to data from EXAFS spectra  

Energy Technology Data Exchange (ETDEWEB)

The EXAFS spectra of the platinum(III) complexes Pt/sub 4/(OAc)/sub 10/(OH)/sub 2/ (I) and Pt/sub 4/ (OAc)/sub 4/(OH)/sub 8/(H/sub 2/O)/sub 2/ (II) have been investigated. It has been found by a curve-fitting method and with the aid of Fourier transformations that the shortest Pt-Pt distances are 2.61 A in complex I and 2.36 and 2.6 A in II. The values of the bond lengths obtained are consistent with the molecular structures proposed for complexes I and II, which contain skeletons of four platinum atoms in the form of a square or a rectangle, as well as with the known literature data on the lengths of Pt-Pt bonds in Pt(III) complexes.

1986-04-01

484

Molecular environment of the IIId subdomain of the IRES element of hepatitits C virus RNA on the human 40S ribosomal subunit  

British Library Electronic Table of Contents (United Kingdom)

The molecular environment of the key subdomain IIId of the internal ribosome entry site (IRES) element of hepatitis C virus (HCV) RNA in the binary complex with the human 40S ribosomal subunit was studied. To this end, HCV IRES derivatives bearing perfluorophenylazido groups activatable by mild UV at nucleotides G263 or A275 in the subdomain IIId stem were used. They were prepared by the complementary addressed modification of the corresponding RNA transcript with alkylating oligodeoxyribonucleotide derivatives. None of the RNA derivatives were shown to be crosslinked to the 18S rRNA. It was found that the photoreactive groups of the IRES G263 and A275 nucleotides are crosslinked to ribosomal proteins S3a, S14, and S16. For the IRES derivative with the photoreactive group in nucleotide G26...

2009-01-01

485

Molecular Characterization of Coprophilous Fungal Communities Reveals Sequences Related to Root-Associated Fungal Endophytes  

British Library Electronic Table of Contents (United Kingdom)

This paper reports the use of molecular methods to characterize the coprophilous fungal communities (CFC) that inhabit the dung of four species of mammalian herbivores at two sites, Sevilleta National Wildlife Refuge (SNWR) in New Mexico and Wind Cave National Park (WCNP) in South Dakota. Results reveal that CFC from domesticated cattle (Bos taurus) at SNWR, and bison (Bison bison) and black-tailed prairie dogs (Cynomys ludovicianus) at WCNP were diverse but dominated primarily by members within eight taxonomic orders, including the rarely cultured and anaerobic order Neocallimastigales. In addition, 7.7% (138 of 1,788) of the sequences obtained from all dung samples were at least 97% similar to root-associated fungal (RAF) sequences previously described from blue grama (Bouteloua gracilis...

2011-01-01

486

Manganese oxide nanowires, films, and membranes and methods of making  

Energy Technology Data Exchange (ETDEWEB)

Nanowires, films, and membranes comprising ordered porous manganese oxide-based octahedral molecular sieves, and methods of making, are disclosed. A single crystal ultra-long nanowire includes an ordered porous manganese oxide-based octahedral molecular sieve, and has an average length greater than about 10 micrometers and an average diameter of about 5 nanometers to about 100 nanometers. A film comprises a microporous network comprising a plurality of single crystal nanowires in the form of a layer, wherein a plurality of layers is stacked on a surface of a substrate, wherein the nanowires of each layer are substantially axially aligned. A free standing membrane comprises a microporous network comprising a plurality of single crystal nanowires in the form of a layer, wherein a plurality of layers is aggregately stacked, and wherein the nanowires of each layer are substantially axially aligned.

2008-10-21

487

Important effects of neighbouring nucleotides on electron induced DNA single-strand breaks  

British Library Electronic Table of Contents (United Kingdom)

In this Letter, we present Quantum Mechanics/Molecular Mechanics (QM/MM) calculations on molecules containing a 2-deoxycytidine-3prime-monophosphate moiety (3prime-dCMPH). In particular, we examine the effect that including neighbouring nucleotides at the Molecular Mechanic (MM) level has on the calculated electron affinities and on the energetic barriers of the C3prime-O3prime bond cleavage. Our results demonstrate that the surrounding nucleotides relocate the excess electron from the p* orbital of the base to a diffuse phosphate-centred orbital, leading to the formation of a dipole-bound anion state. Both the electron affinities and the activation energy of C3prime-O3prime bond cleavage are strongly increased.

2009-01-01

488

Humectant. Hoshitsuzai  

Energy Technology Data Exchange (ETDEWEB)

This paper elucidates the effect of humectant performance on the wettability of the skin. Humectants are divided into the organic compounds, such as polyols, the organometallic compounds, such as sodium lactate and pyrolidone sodium carboxylate, and the water soluble high molecular compounds, such as polyethylene glycol and hyaluronic acid. Firstly, hygroscopic performances and characteristics of various hcmectants are illustrated. Then, the humectant performance of the skin and relation between amino acid in the horny layer and moisture content are described. The humectant performance possessed in the intercellular lipid of horny layer is also described. Furthermore, are explained the wettability of the skin by cosmetics and the role of humectant as an emulsifying assistant. A mechanism of the dry skin, improvement effect of the skin by humectants, and combining effect of the humectants are presented. Are also presented the nonaqueous emulsification, amino acid ...

1993-06-20

489

Highly-sensitive ion selective electrode based on molecularly imprinted polymer particles for determination of tetracycline in aqueous samples  

British Library Electronic Table of Contents (United Kingdom)

In this work, a highly-sensitive polymeric membrane ion selective electrode for determination of tetracycline was constructed by using molecularly imprinted polymer (MIP) particles as quasi-ionophore. The water-compatible MIP particles targeting tetracycline were synthesized with tetracycline as a template molecule, methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, 2,2?-azobisisobutyronitrile as an initiator and lanthanum ion as a mediator. Benefited from the distinctive performance of the quasi-ionophore and the optimized composition of the membrane and the inner filling solution, the lower detection limit of the electrode was decreased to about 1 ? 10?8 mol/l. It exhibited a good electrode slope 59.8 mV/decade near the theoretical Nernstian one, ...

2011-01-01

490

High power GaInP-AlGaInP quantum-well lasers grown by solid source molecular beam epitaxy  

Science.gov (United States)

AlGaInP-based quantum-well laser diodes operating at wavelengths near 680 nm have been grown by all solid source molecular beam epitaxy (SSMBE). The lowest room temperature threshold current densities obtained from shallow rid structures were 300 A/cm{sup 2} and 330 A/cm{sup 2} for pulsed and continuous wave operation, respectively. The dependences of the differential quantum efficiency and threshold current density on the cavity length were also studied in this preliminary SSMBE work. The internal quantum efficiency of 87--89% and the internal losses of 7--10 cm{sup {minus}1} were obtained.

1996-03-01

491

Formation of pentagonal Cu nano wires  

Energy Technology Data Exchange (ETDEWEB)

The development of nano/molecular devices will require atomic-sized electrical contacts or nano metric conductors for wiring. As metal nano wires exhibit quantized conductance at room temperature, quantum transport effects will play an important role in the practical implementation of nano devices. As copper is currently used as interconnecting metal in standard microelectronics, the characterization of Cu nano wire properties deserves special attention. In this work, we show a detailed study of structural and electronic properties of atomic-sized Cu wires. In particular, we have established a complete correlation between the conductance and the structure by associating real-time atomic resolution transmission electron microscopy imaging with molecular dynamic simulations, conductance measurements and conductance calculations. Our study has revealed the structural relaxation of Cu wires forming a pentagonal atomic arrangement along the [110] ...

2004-07-01

492

Effects of molecular mobility on high resolution solid state NMR spectra: model systems  

Energy Technology Data Exchange (ETDEWEB)

It is the intention of this paper to point to some of the problems due to molecular motion and to suggest a few solutions to those problems. A few examples will be presented of model systems which demonstrate the effects of motion on the NMR spectroscopy and a very qualitative example of severe spectral distortion in fulvic acids will be shown. In the following discussions we will use concepts derived from the oft repeated thermodynamic picture shown in figure 1. When dealing with a homogeneous, pure compound this picture is sufficient but in a heterogeneous mixture, it is likely that there will be different compounds and different domains all with slightly different versions of figure 1 with poor thermodynamic contact between them. Thus optimal conditions for cross polarization in one domain may be totally inappropriate for another. 59 refs., 10 figs.

1986-01-01

493

Development of polarizable chloroform potential and its applications to chloroform-water liquid-liquid interface  

Energy Technology Data Exchange (ETDEWEB)

An all-atom polarizable chloroform (CHCl{sub 3}) potential model has been developed using the classical molecular dynamics techniques. This potential is shown to reproduce reasonably well the structural, dynamical, and thermodynamic properties of bulk liquid CHCl{sub 3} at various temperatures and pressures. With this potential, we carried out computer simulations to investigate the CHCl{sub 3}-H{sub 2}O liquid/liquid interface. Detailed structural and electrical properties at the interface will be analyzed via the density profile, radial distribution functions, molecular orientation, hydrogen bonding, and the z-dependent dipole distributions. Comparison will also be made to the results of the CCl{sub 4}-H{sub 2}O liquid/liquid interface.

1996-10-01

494

Determination of low-molecular-weight organic acids and inorganic anions by gradient elution chromatography  

Energy Technology Data Exchange (ETDEWEB)

Conditions of the separation and detection of organic and inorganic anions by gradient ion chromatography and suppressed conductivity detection were studied, and the procedure of gradient elution was optimized. A detection limit of 1 x 10{sup -3} {mu}g x L{sup -1} was obtained using the pre-concentrated column and most relative standard deviations obtained in the determination of seven organic and inorganic anions were below 5%. This method was proved to be simple, rapid and accurate for the separation and determination of low-molecular-weight organic acids and inorganic anions and could be applied in the analysis of the samples from water and steam systems of thermal power plants with satisfactory results. (orig.)

2007-03-15

495

Crossover of the magnetic levels and adiabatic magnetization of the mesoscopic cluster V15  

British Library Electronic Table of Contents (United Kingdom)

The magnetic three spin-1/2 model for nanometer-scale molecular cluster V15 is analyzed with the emphasis on the origin of the mixing of different spin levels in the resonance fields that is generally important for the problem of single molecular magnets. The zero-field splitting in the ground quadruplet (two Formula Not Shown levels) is shown to depend mainly on the normal component of AS exchange meanwhile the zero-field splitting in the excited Formula Not Shown multiplet is a second order effect with respect to in-plane components of AS exchange. The normal component of the AS exchange is shown to lead to the exact crossing of the magnetic sublevels at the arbitrary direction of the field. The positions of two crossing/anticrossing points in the ground manifold depend mainly on the iso...

2006-01-01

496

Collisions between H"+ and H_2 at kilo-electron-volt energies: Absolute differential cross sections for small-angle direct, single-, and double-charge-transfer scattering  

International Nuclear Information System (INIS)

Measurements of absolute differential cross sections for H"+-H_2 direct, single-, and double-charge-transfer scattering at 0.5, 1.5, and 5.0 keV are reported at laboratory scattering angles less than 1 degree with an angular resolution of approximately 0.02 degree. The cross sections exhibit deep interference oscillations in single-charge-transfer scattering, but no such oscillations are present in direct and double-charge-transfer scattering. Theoretical cross sections derived using the diatoms-in-molecules method to describe the molecular states in a semiclassical molecular-orbital three-state close-coupling model within a semiclassical framework agree satisfactorily with the experimental results.

497

Chemical Analysis of Solid-State Irradiated Human Insulin  

British Library Electronic Table of Contents (United Kingdom)

Purpose To study the chemical modifications induced upon irradiation of solid human insulin at radiosterilization doses and investigate the influence of the absorbed dose on radiolysis. Materials and Methods Volatile radiolytic products were monitored by gas chromatography coupled with mass spectrometry (GC-MS) and non-volatile products by two different high performance liquid chromatography (HPLC) methods: the formation of higher molecular weight proteins was assessed by size exclusion liquid chromatography whereas assays for related compounds and chemical potency tests were carried out using reverse-phase HPLC-UV. Conformational changes were investigated by measurements of circular dichroism. Results After gamma irradiation at 10?kGy, the recovery of insulin was 96.8%; higher molecular w...

2006-01-01

498

Assessing the acid properties of desilicated ZSM-5 by FTIR using CO and 2,4,6-trimethylpyridine (collidine) as molecular probes  

British Library Electronic Table of Contents (United Kingdom)

A series of desilicated ZSM-5 catalysts previously shown to have improved catalytic performance in the MTG (methanol-to-gasoline) reaction [M. Bjorgen, F. Joensen, M.S. Holm, U. Olsbye, K.-P. Lillerud, S. Svelle, Appl. Catal. A 345 (2008) 43] was subjected to thorough examination using FTIR. Clearly, defects represented by internal Si-OH sites are removed upon NaOH treatment. In a parallel manner, free Si-OH sites increase in concentration and the results point to a selective mechanism for formation of mesopores as the framework dissolution preferentially takes place at defective sites in the crystallites. The acid properties of the desilicated materials were investigated by applying CO and collidine (2,4,6-trimethylpyridine) as molecular probes. Monitoring the induced frequency shifts upo...

2009-01-01

499

Active hydrogen by chemical ionization mass spectrometry.  

Science.gov (United States)

A means of determination of a ctive hydrogen of hydroxyl, carboxyl, sulfhydryl, amino, amido and sulfonamido groups by chemical ionization mass spectrometry using ammonia and trideuterioammonia as reagent gases is described. The method is based on exchange of active hydrogen for deuterium occurring during the chemical ionization process using trideuterioammonia, with comparison of m/z for ammonium adduct [M + NH1]+ and trideuterioammonium adduct [M--nH + nD + ND4]+, or of protonated molecular ion [M + H]+ and deuteronated molecular ion [M--nH + nD + D]+ yielding the number of active hydrogens. Applications have been made to several classes of biologically important compounds. PMID:427257

1979-01-01

500

A mechanistic understanding of production instability in CHO cell lines expressing recombinant monoclonal antibodies  

British Library Electronic Table of Contents (United Kingdom)

Abstract One of the most significant problems in industrial bioprocessing of recombinant proteins using engineered mammalian cells is the phenomenon of cell line instability, where a production cell line suffers a loss of specific productivity (qP). This phenomenon occurs with unpredictable kinetics and has been widely observed in Chinese hamster ovary (CHO) cell lines and with all commonly used gene expression systems. The underlying causes (both genetic and physiological) and the precise molecular mechanisms underpinning cell line instability have yet to be fully elucidated, although recombinant gene silencing and loss of recombinant gene copies have been shown to cause qP loss. In this work we have investigated the molecular mechanisms underpinning qP instability over long-term sub-cult...

2011-01-01