bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and molecular structure analysis of nano‐sized methacryl‐grafted polysiloxane resin for fabrication of nano hybrid materials
Authors: Eo Young‐Joo , Lee Tae Ho , Kim Se Yun , Kang Jeung Ku , Han Young Soo , Bae Byeong‐Soo 
Published: February 2005

AbstractThe molecular structures of methacryl‐grafted polysiloxane resins from 3‐(trimethoxysilyl)propyl methacrylate (MPTS) and diphenylsilanediol (DPSD) were determined by theoretical computation and experimental measurement. The molecular structures obtained from theoretical computation coincided well with those from experimental measurement, and we found that the structural changes in the resins could be controlled by precursor compositions. While molecular weights and polysiloxane chain lengths of the resins increase with DPSD contents, their molecular sizes do not vary significantly. In the present study, molecular sizes and shapes of the resins with various compositions are hypothesized theoretically and proven experimentally. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 827–836, 2005
Reference points and reference directions for size-based indicators of community structure
Authors: Jennings Simon , Dulvy Nicholas K. 
Published: February 2005

AbstractSize-based community and ecosystem metrics, such as mean body mass and the slopes of size spectra, have been proposed as indicators to support the Ecosystem Approach to Fisheries Management (EAFM). These metrics show relatively consistent responses to size-selective exploitation, and “unexploited” indicator reference points may be predicted with models of size-structured foodwebs. Whereas unexploited reference points provide a baseline for assessing the relative magnitude of fishing impacts, target or limit reference points are needed to guide management. Values for target or limit reference points are difficult to justify on scientific grounds. However, given that fishing impacts in most ecosystems need to be reduced to meet the objectives of the EAFM, we argue that reference directions provide alternative medium-term management targets. We show that the power of surveys to detect trends consistent with reference directions depends on the range of body size classes included in the analysis. Selection of different size ranges will weight metrics to respond to the release of small fish from predation, the depletion of larger individuals as a consequence of exploitation, or both. Such weightings may not be consistent over time, because the differential vulnerability of larger species, within-population changes, predator–prey relationships, and the effects of competition depend on contemporary rates of fishing mortality and the history of exploitation. The power of the surveys investigated is poor on time scales of less than 5–10 years. Therefore, size-based indicators provide better support for medium-term, rather than year-on-year, management decision making.
A Stand-Alone Monitoring System for Reliable Unattended Operation of a Commercial Preparative LC/MS Purification System
Authors: Paulson James L. 
Published: February 2005

Commercially available preparative liquid chromatograph/mass spectrometer (LC/MS) systems are commonly used in drug discovery research to purify large numbers of compounds made by parallel synthesis techniques. The systems in our lab are comprised of individual instruments that communicate continuously with control software in order to collect specific compounds based on mass triggering. Over time, communication errors may cause improper system operation, and excessive pressure during injection may cause system damage or a leak. The risks of sample loss and safety hazards precluded unattended overnight operation of the purification systems. A stand-alone monitoring system was developed to ensure proper purification system operation. Custom sensors and software are used to identify failures and remotely control power to the purification system. In response to a failure, the monitoring system will either shut down the purification system or, if possible, selectively reboot an instrument to allow continued operation. With the creation of the monitoring system, the purification system can be run unattended with
New Circuit for the Measurement of Very Short Delays
Authors: Lepri F. , Mezzetti L. , Stoppini G. 
Published: February 2005

A circuit for the measurement of time intervals down to 10−10 sec is described.
The circuit works on the principle of transforming the delay τ to be measured into a flat-topped signal whose amplitude is proportional to τ, and whose length is independent of τ and controllable at will within wide limits (up to about 100 μsec). The precision and stability of the circuit are discussed.
New Method of Flow Calorimetry
Authors: Hoxton L. G. , Weiss R. A. 
Published: February 2005

A relative method has been developed whereby two conventional flow calorimeters, connected in a series combination, serve to determine the ratio of the Cp of a fluid in one state to that in another, this ratio being measured as a function of resistance ratios. Measurements of flow rate and of power input are not required, while simplifications in other respects are also to be found.
Although its determinations are not ``absolute,'' the gains in speed and simplicity, without loss of accuracy, are considered sufficient to warrant its use in exploratory work or in researches requiring the extension of known values over new temperatures and pressures, as is often the case with tables. The method is offered, therefore, as a worthwhile research tool. A brief description is given.
Cantilever Pneumograph
Authors: Whalen William J. , DeHaan Robert L. 
Published: February 2005

A simple device utilizing a resistance wire strain gauge for the recording of respiratory movements is described.
Changes in chest and diaphragmatic tone may be recorded in spite of the variations in ambient temperature which markedly affect conventional bellows-type pneumographs. Greater sensitivity is obtained and leaks in the system are not a problem. The frequency response is well above the respiratory rate of panting animals. Finally, the cost is minimal.
Large Scintillators as Threshold Detectors for High-Energy Processes
Authors: Thresher J. J. , Van Zyl C. P. , Voss R. G. P. , Wilson R. 
Published: February 2005

The design is described of several liquid organic scintillation counters which have been used to detect 100-Mev neutrons and gamma rays with the exclusion of lower-energy particles and quanta.
The neutron counter efficiency is a few percent and is nondirectional, properties not possessed by a more conventional counter telescope system. The gamma-ray counter has an efficiency of about 50%, with a line width of about 10%.
Particular problems arise in the use of these counters; counting rate stability is difficult to achieve; the maximum counting rate is limited by the pileup of individual pulses due to their finite width. These problems are discussed in detail and some solutions mentioned.
Low-Level Thermocouple Amplifier and a Temperature Regulation System
Authors: Dauphinee T. M. , Woods S. B. 
Published: February 2005

A breaker-type dc amplifier suitable for measurement of thermocouple voltages as low as 10−2 μvolt is described. Mechanically driven ``choppers'' operating at 40 cps are used to modulate the thermocouple signal and later demodulate the amplifier output. Both input and output are floating and may normally be operated connected to ungrounded circuits. Over-all voltage gain is approximately 107 while the zero error corresponds to less than 10−2-μvolt dc input within five minutes of turning on. The amplifier contains only standard components and details of a suitable chopper which can be made in the laboratory are given.
A temperature regulation circuit is described which is suitable for precision control of temperature in conjunction with a differential thermocouple. An indicated temperature match as close as 0.0002°C has been obtained with a single couple.
Ion Source for the Production of Multiply Charged Heavy Ions
Authors: Anderson Carl E. , Ehlers Kenneth W. 
Published: February 2005

A pulsed, cold-cathode ion source has been developed to produce multiply charged ions for use in a linear accelerator. Milliampere currents of such ions as He42+, C122+, N143+, O163+, Ne203+, and smaller currents of S325+ and A406+ have been produced in focused beams.
Mass spectra of the various ionization states produced by the arc are presented. Constructional details of the source and the associated electronic equipment are given, and operating characteristics of the source and ion extraction are discussed.
Electrolytic Tank, Design and Applications
Authors: Kennedy Phyllis A. , Kent Gordon 
Published: February 2005

The theory of the electrolytic tank analog as a device for the solution of potential problems is reviewed, and some of the more important applications are discussed.
The mechanical requirements of an electrolytic tank design are stated. A description of the Harvard tank is given, indicating how these problems were met. The figure of mechanical uncertainty for the Harvard tank is estimated to be 0.01 in.
A discussion of experimental error in tank measurements covers problems of electrode and electrolyte materials a well as difficulties resulting from surface tension.
Control experiments for determining the accuracy of level and tilted tank measurements are described, and the results presented. Although high accuracy is possible in the level tank, only great care can produce results in the tilted tank which are reliable to within 3%.
Achromatic Beam Translation Systems for Linear Accelerators
Authors: Brown K. L. 
Published: February 2005

The beam of electron linear accelerators has desirable geometric properties, but usually contains undesirable secondary particles and a relatively broad energy spectrum.
In order to dispose of the secondary particles and, at the same time, establish control of the width of the energy spectrum, several magnetic deflection systems have been considered for the Stanford machines. Two such systems are described here, one of which has been adopted for three of the Stanford accelerators. Both systems are capable of translating the beam without energy dispersion.
Magnetic Recorder for Nuclear Pulses
Authors: Cavanagh P. E. , Boyce D. A. 
Published: February 2005

A simple reliable process is described for recording the amplitudes of individual pulses on magnetic tape. This enables the pulse analysis to be performed after the experiment, and under optimum conditions. Low counting rates may be recorded with the tape moving slowly, and then speeded up on playback, so that, for example, a twenty-four hour run may occupy only seven minutes analyzer time. The recording process is strictly linear over a range of signal/rms noise of up to 300/1. A maximum rate of 4000 pps may be recorded. The resolution varies with pulse amplitude, but, over the upper two-thirds of the linear range the relative spread assumes a very nearly constant value of about 3%.
A further development is described in which gated time coincident pulses are recorded simultaneously on twin tracks of the same tape. In data gathering power this system is better than an array of thirty conventional thirty channel pulse analyzers. It may also be applied to the simultaneous recording for separate analysis of the outputs of up to about ten independent detectors.
Machine for the Production of Microelectrodes
Authors: Winsbury G. J. 
Published: February 2005

A description is given of a machine designed to produce microelectrodes from a standard 3-mm Pyrex glass tube. The glass tube is heated by a platinum coil and drawn into microelectrodes by a vertical two-stage pull. The first pull is by gravity and the second by an electromagnet. The operation is entirely automatic. After the machine is switched on adjustable microswitches control the sequence of operation and finally switch the machine off when the microelectrodes are drawn. Two identical microelectrodes are produced per minute. The microelectrode tip diameters may be varied from 0.5 to 10 μ. The taper towards the tip may also be varied within wide limits to suit different experiments.
Advantages of the machine over earlier microelectrode pullers are discussed together with a description of a rapid method of filling microelectrodes with conducting solutions.
``Glo-Ball'' Development
Authors: Steinhaus James F. 
Published: February 2005

The term ``glo-ball'' is used to designate a small, thin-walled, partially evacuated glass sphere containing helium, used for investigating electric field distributions in rf resonant cavities. Ionization, or firing, of the gas in the glo-ball indicates a given potential gradient across it; in field investigations a monitoring loop is used to record the voltage required in the cavity to produce this ionization. Glo-balls were developed specifically for their application to linear accelerators.
Experiments were conducted to provide a method of making glo-balls, under controlled conditions with known constituents, that would have a stable and relatively low firing gradient.
Factors associated with the making of a glo-ball were determined, and a spectroscopic analysis identified the gas components. It is now possible to make a ball that fires at a minimum voltage gradient with excellent stability. Other characteristics of the glo-ball pertinent to its use as a field-measuring device were investigated.
Correction for Phosphor Backscattering in Electron Scintillation Spectrometry
Authors: Freedman M. S. , Novey T. B. , Porter F. T. , Wagner F. 
Published: February 2005

An iterative numerical integration procedure has been developed to correct both beta spectra and differential beta-gamma directional correlations for the effects of finite instrument energy resolution including the effect of backscattering from a scintillation detector.
The method has been tested and found to reproduce the true spectral shape in the cases of Re186, Au198, Tl204, and to allow separation of composite beta spectra as in the case of W187. Application of the method is limited to maximum beta energies exceeding 200 kev.
Continuously Indicating Precision Magnetometer
Authors: Green G. W. , Hanna R. C. , Waring S. 
Published: February 2005

A flat coil is suspended in a magnetic field so that in equilibrium it is coplanar with the field and can oscillate about an axis in the plane of the coil perpendicular to the field. When an alternating current is passed through the coil the system behaves as an inductance in series with a condenser of capacity inversely proportional to the square of the magnetic field. The principle has been applied to the measurement of magnetic field. The instrument is capable of a precision of one part in 102 with simple auxiliary apparatus.
The application to a particle analyzing magnet is described. With some elaboration the magnetic field can be measured and stabilized to one part in 104 in the range 1–12 kilogauss.
Fast Read-Out Chronotron System
Authors: Meunier Robert , Davidson Gilbert 
Published: February 2005

A new electronic read-out system has been devised which enables one to obtain a fast answer from a chronotron to be used with accelerator beams of particles. It allows for an analysis of time delay with variable and continuous time intervals. The timing is pulse-height independent with an accuracy increasing for large pulses. The recovery time is in the range of one microsecond.
With delay-line clipped coincidence pulses from two photomultipliers being fed into a 12-channel chronotron with a 30-mμsec range, a time resolution with half-width at half maximum of 1.2 mμsec was readily obtained. Using only 4 channels, with a range of 10 mμsec, a half-width at half maximum of 6×10−10 sec was observed. A simplified version with only three channels has made a useful fast coincidence circuit.
Dosimeter for High-Energy Neutrons
Authors: Baranov P. S. , Goldanskii V. I. , Roganov V. S. 
Published: February 2005

A neutron detector with a threshold at 20.6 Mev is described which is based on the C12(n,2n)C11 reaction in liquid organic scintillators.
The efficiency of the detector is almost independent of neutron energy from ∼40 Mev to ∼400 Mev. The detector can be used to measure with an error of 6% high-energy neutron fluxes in the tolerance range (20–50 n/cm2 sec).
Point-Focusing Two-Crystal X-Ray Monochromator for X-Ray Diffraction
Authors: Furnas Thomas C. 
Published: February 2005

Crystal monochromators can provide the exceptionally fine collimation requisite for the study of small-angle diffraction phenomena. To obtain sufficient intensity and contrast it is necessary not only to bend the crystal but also to use two crystals in tandem with their focal circles mutually orthogonal.
The apparatus described uses the x-ray ``weak window'' line source to illuminate the (200) planes of mica in transmission and the (101̄1) planes of a cylindrically ground, polished, and etched quartz crystal in reflection. Symmetrical couple mounts were used to minimize aberrations. The camera essentially isolates the Kα1 component and consequently reduces diffuse background and general radiation artifacts as shown by pertinent applications to collagen and feather keratin. Although operating in air and using exposure times comparable (50–250 hr) to those encountered with aperture-collimated systems, the camera has resolved the central first order of the 640-A macroperiod of collagen fibers and is capable of resolving consecutive orders of spacings as high as ca 3800 A.
The Johansson, Johann, and Cauchois geometries are illustrated in a new manner to show the importance of weak and large sources of x-rays, to demonstrate the focal pattern characteristic of two-crystal point-focusing arrangements, and to show why mosaic crystals are incapable of the fine focus required.
Feedback Controlled Heat Conductivity Gauge for Measuring Pressure in Vacuum Systems
Authors: Leck J. H. , Martin C. S. 
Published: February 2005

This paper describes a simple feedback circuit for the hot wire Pirani gauge. This gauge is used for measurement at low pressures where the heat conducted away from a thin hot wire is a function of the gas pressure. The wire is included in a Wheatstone bridge circuit which serves both to heat the wire and to measure its temperature. In the circuit described here the heat input is adjusted automatically so as to keep the wire temperature approximately constant over a wide range of pressure changes. This is achieved by supplying the power from a magnetic amplifier which is controlled by the wire temperature, a fall in temperature increasing and a rise in temperature decreasing the power supply.
In this way pressure measurements can be made over the range zero to 3 mm Hg with wire temperatures of the order of 50 to 100°C by using either the feedback signal or the power output from the amplifier to give a measure of the pressure.
Propane Bubble Chamber in a High Magnetic Field
Authors: Oswald Larry O. 
Published: February 2005

A liquid propane chamber 3.25 by 6.5 by 13 in., operating in a magnetic field of 22 000 gauss, is described. A simple compact dark-field type of illumination is used; this is discussed. For personnel and equipment safety a secondary pressure vessel is incorporated in the design. Special reference is given to some of the construction and design problems.
A brief summary of the operation of the propane chamber in the 6.2-Bev neutron beam is given.
Direct Reading Minority Carrier Lifetime Measuring Apparatus
Authors: Engler A. R. , Kevane C. J. 
Published: February 2005

An apparatus is described which permits the direct reading of minority carrier lifetimes greater than 10 microseconds. The decay of optically injected excess minority carriers is compared with voltage decay in an RC circuit and lifetimes are read directly from a calibrated dial. Measurements can be made quickly without critical adjustment.
An alignment chart for rapid calculation of surface recombination velocity from lifetime data is included.
Apparatus for Studying Convection under the Simultaneous Action of a Magnetic Field and Rotation
Authors: Nakagawa Yoshinari 
Published: February 2005

An apparatus for the study of the instability of a layer of mercury heated from below and subjected to the simultaneous action of a magnetic field and rotation is described. The equipment is designed to examine the mode of convection and the dependence of the critical Rayleigh number (=αgβcd4/κν, where g denotes the acceleration due to gravity, βc the critical adverse temperature gradient, α the depth of the layer, κ the thermometric conductivity, ν the kinematic viscosity, and α the coefficient of volume expansion) for the onset of instability on the values of nondimensional parameters Q1 (=σH2d2/π2ρν, where H is the strength of the magnetic field, σ the electrical conductivity, and ρ the density of fluid) and T1 (=4Ω2d4/π4ν2, where Ω denotes the angular velocity of rotation), the features proven to be essential in such studies.
By using a reconditioned cyclotron magnet as a part of the experimental arrangement, this apparatus covers wide ranges of parameters Q1 (from 10 to 106) and T1 (from 105 to 1010).
Typical results that can be obtained by this apparatus are discussed with a few illustrative examples.
Contact Resistance Measurements at Low Loads
Authors: Flom D. G. 
Published: February 2005

A modification of the fine-wire loop technique for studying surface contact resistances, as developed originally by Savage and Flom, is described. The principal change is substitution of quartz fiber for platinum wire as the resilient part of the probe. The contact end of the probe consists of either platinum or gold—other metals could be used as well.
An additional improvement is the provision for gradually increasing the applied force between the probe and surface at a low, known rate. This can provide information, not only on the electrical and physical durability of the film, but also on the changing bulk characteristics of the contact junction.
Applications in which the quartz fiber probe has been used for studying silver-plated aluminum contacts, gold-plated silver contacts, and copper-Teflon films on copper are discussed.
Gas Circulating Apparatus Containing a Magnetic Balance
Authors: Scala L. C. , Hickam W. M. , Langer A. 
Published: February 2005

A gas circulating system is described in which a sample undergoing thermal decomposition can be weighed continuously by means of a magnetic balance having a sensitivity of the order of 0.1 mg. Changes of composition in the gases contained in the system are determined by withdrawing samples directly into a mass spectrometer for analysis. Accurate quantitative measurements of the uptake and evolution of gases during the degradation process are thus obtained, providing an insight into the reactions that occur.
This simple system should prove useful in many other fields of investigation.
Intracardiac Catheter Microphone
Authors: Welkowitz Walter , Traite Max 
Published: February 2005

A microphone is described that can be encased in a small-bore plastic catheter. The small size permits insertion directly into the heart and the precise localization of the origin of heart sounds.
The unit uses a two-section piezoelectric ceramic, operated in a bender mode. The frequency response is flat up to 3000 cps.
The sensitivity over the flat frequency range is −124 db referred to 1 v/μbar.