bluuebunny/crossref_metadata_2025 huggingface dataset:
Empowering Students: Class-Generated Course Rules
Authors: DiClementi Jeannie D. , Handelsman Mitchell M.
Published: January 2005

After we gave 2 classes of introductory psychology students the syllabus, the first class (the experimental group) generated rules for classroom behavior. The instructor presented the second class (the comparison group) with the list of rules and said they were instructor generated. Students rated the rules, several aspects of the course, and the instructor. The comparison group (n = 88) reported higher frequencies of negative behavior by class members. Students in the experimental class (n = 62) rated the instructor more positively. The groups did not differ in grades, perceived fairness, or perceived importance of the rules.
Use of Primary Source Readings in Psychology Courses at Liberal Arts Colleges
Authors: Oldenburg Christopher M.
Published: January 2005

This study examined how frequently psychology professors at liberal arts colleges assign primary source readings. Professors provided information on 576 courses. Frequent use of primary sources suggests that professors view such readings as a valuable component of the psychology curriculum. Professors assigned primary source material in 70.8% of the courses. Professors assigned articles from scholarly journals more often in higher level courses and courses with lower enrollments. Professors reported more satisfaction with the classroom discussion of primary sources in smaller, more advanced courses. This study also provides a list of readings identified most frequently by participants as being effective.
Elaborations of Introductory Psychology Terms: Effects on Test Performance and Subjective Ratings
Authors: Balch William R.
Published: January 2005

Undergraduate students participated in an experiment designed to evaluate different types of elaborations on definitions of 16 psychology terms. First, participants received booklets presenting the definition of each term, followed by 1 of several elaborations: an example, a mnemonic, a paraphrase, or a repeated definition (the nonelaborating control condition). Then students received a multiple-choice test consisting of questions both on the definitions and on novel examples of the terms. Compared to repeated definitions, examples and mnemonics—but not paraphrases—improved scores on each type of question. However, students' subjective ratings did not always reflect the effectiveness of the elaborations in improving test performance.
Effect of Textbook Study Guides on Student Performance in Introductory Psychology
Authors: Dickson K. Laurie , Miller Michelle D. , Devoley Michael S.
Published: January 2005

We experimentally investigated the effect of required textbook study guides on undergraduates' multiple-choice exam performance for introductory psychology. Students in 2 sections participated. Students required to complete the study guide performed significantly better than students in the control section. Students who reported completing 75% or more of the study guide did not perform significantly better than students who completed 25% or less. Results offer support for the effectiveness of study guides in courses that use multiple-choice exams; however, more exercises may not enhance performance compared to fewer exercises. Students who used the study guide had a positive perception of the usefulness of the study guide, and most stated that they would voluntarily use one in the future.
Demonstrating the Importance of Question Wording on Surveys
Authors: Madson Laura
Published: January 2005

This classroom activity demonstrates the importance of question wording on surveys. In the activity, students compared data from 2 versions of a short questionnaire that differed only in the wording of the questions and the response scales. Class discussion focused on how wording affected the data and, consequently, how difficult it would be to draw valid conclusions from the data. After participating in the activity, students were better able to identify and correct poorly worded items and response scales on a subsequent survey.
Some aeromechanical aspects of insect-like flapping wings in hover
Authors: Żbikowski R , Knowles K , Pedersen C B , Galiński C
Published: January 2005

Micro air vehicles (MAVs) are defined as flying vehicles ca. 150 mm in size (hand-held) weighing 50–100 g, and are developed to reconnoitre in confined spaces (inside buildings, tunnels, etc.). For this application insect-like flapping wings are an attractive solution and hence the need to realize the functionality of insect flight by engineering means. Insects fly by oscillating (plunging) and rotating (pitching) their wings through large angles, while sweeping them forwards and backwards. During this motion the wing tip approximately traces a figure-of-eight and the wing changes the angle of attack (pitching) significantly.

This paper presents some aspects of aerodynamic modelling and mechanical design pertinent to engineering realization of insect-like flapping wings on the MAV scale. The aerodynamic modelling uses an indicial Polhamus approach which is implemented in a modular manner. Comparisons are presented with experimental force data from a dynamically scaled insect model and generally show good agreement. The design is then described of a four-bar linkage mechanism to drive an insect-like flapping-wing motion. The indicial Polhamus aerodynamic model was used as part of the design process to predict wing loading. This highlighted some interesting interactions between the position of the wing pitch axis and its loading. The paper concludes with some directions for future work in this challenging field.
Decentralized approach to unmanned aerial vehicle navigation: Without the use of the global positioning system and preloaded maps
Authors: Kim Jonghyuk , Ong Lee Ling , Nettleton E , Sukkarieh S
Published: January 2005

In this paper the issue of autonomous navigation is addressed, i.e. the ability for a navigation system to provide information about the states of a vehicle without the need for a priori infrastructures such as the global positioning system (GPS), beacons or preloaded maps of the area of interest. The algorithm applied is known as simultaneous localization and mapping (SLAM). It is a terrain-aided navigation system that has the capability for on-line map building, while simultaneously utilizing the generated map to bound the errors in the navigation solution. As no a priori terrain information nor initial knowledge of the vehicle location is required, this algorithm presents a powerful navigation augmentation system. More importantly, it can be implemented as an independent navigation system. This paper also describes a decentralized SLAM algorithm that allows multiple vehicles to acquire a joint three-dimensional map via a decentralized information fusion network. The key idea behind this decentralized SLAM is to represent the map in information form (negative log likelihood) for communication. Experimental results are provided using computer simulation to demonstrate the single-vehicle and multi-vehicle SLAMs without the use of GPS and preloaded maps.
Stiffness and damping characteristics of lubricated ball bearings considering the surface roughness effect. Part 1: Theoretical formulation
Authors: Sarangi M , Majumdar B C , Sekhar A S
Published: January 2005

The stiffness and damping characteristics of isothermal, elastohydrodynamically lubricated point contact problems are evaluated numerically considering the surface roughness effect and variation in viscosity with pressure. A set of equations under steady-state and dynamic conditions is derived from the classical Reynolds equation using the linear perturbation method. The elasticity equation and steady-state Reynolds equation are solved simultaneously using the finite difference method with the successive over-relaxation scheme, whereas the dynamic pressures are found after solving the set of perturbed equations using the previously obtained steady-state pressures. The load capacity is obtained from the steady-state pressure distribution. The stiffness and damping coefficients of the contact are determined using the dynamic pressures. Then the overall stiffness and damping matrices of the ball bearing are obtained from the load distribution, coordinate transformation, and compatibility relations.
Wear characteristics of injection-moulded unfilled and glass-filled nylon 6 spur gears
Authors: Senthilvelan S , Gnanamoorthy R
Published: January 2005

The tribological behaviour of polymer and polymer composite gears is reported in this paper. Gear tests were conducted using a power absorption-type gear test rig. Injection-moulded nylon 6 and glass-filled nylon 6 gears were tested at different speeds and loads. Gear rotational speed influences the tooth wear of unfilled and glass-filled nylon 6 injection-moulded gears due to the change in contact period of teeth in mesh. When the polymer-based gear drives a steel gear, the difference in the elastic moduli of the mating materials causes rotational lag during gear running. When the polymer gears transmit a higher torque, a higher amount of rotational lag causes an excessive wear in the dedendum region of the polymer gear. In the cases of both unfilled and glass-filled nylon 6 gears, at higher-torque test conditions, non-uniform wear on the gear tooth surface was observed. Glass-filled nylon 6 gears showed a better wear resistance than the unfilled nylon 6 gears due to the improved compressive strength, creep resistance, and elastic modulus. A detailed wear particle analysis was carried out to understand the gear wear mechanism. The contact stress and gear material hardness affect the gear wear mechanism.
Boundary element analysis of a plate on an elastic foundation loaded by a twisted annular rigid stamp
Authors: Pavlou D G
Published: January 2005

The contact problem of an elastic plate on an elastic foundation under torsional surface tractions is solved numerically by the boundary element method (BEM). The BEM solution presented in this paper employs a new Green's function of the bonded dissimilar elastic space under a singular tangential loading source which has been developed by the author recently. Using the proposed technique, no multi-region modelling for the bimaterial plate foundation is necessary. The numerical formulation and results of typical examples are included.
An improved elastic-plastic contact model of rough surfaces in the presence of adhesion
Authors: Mukherjee S , Ali S M , Sahoo P
Published: January 2005

The paper describes a theoretical study of adhesion at the contact between rough surfaces with small-scale surface asperities using an elastic-plastic model of contact deformation that is based on accurate finite element analysis (FEA) of an elastic-plastic single asperity contact. The model considers a large range of interference values from fully elastic through elastic-plastic to fully plastic regimes of contacting asperities. The well-established elastic and plastic adhesion indices are used to consider the different conditions that arise as a result of varying load and material parameters. The loading and unloading behaviour for different combinations of these adhesion indices are obtained as functions of mean separation between the surfaces. Comparison with a previous elastic-plastic model that was based on some arbitrary assumptions is made, showing significant differences.
Wear mechanisms and transitions in railway wheel steels
Authors: Lewisa R , Dwyer-Joyce R S
Published: January 2005

The need to improve safety and reduce costs means that new specifications are being imposed on railway wheel wear. These mean that more durable wheel steels are required. In order to develop such materials, a greater understanding is needed of the wear mechanisms and transitions occurring in wheel steels.

In this work, twin-disc wear testing has been carried out to study the wear characteristics of R8T railway wheel steel. The results have indicated that, compared with previous wheel steels, R8T offers greater wear resistance. Three wear regimes were identified; mild, severe, and catastrophic. Wear rates were seen to increase steadily initially and then to level off, before increasing rapidly as the severity of the contact conditions increased. This paper is concerned with the form of the data and the reasons for the transitions.

Analysis of the contact conditions indicated that the first transition in the wear rate was caused by the change from partial slip to full slip conditions at the disc interface. Temperature calculations for the contact showed that the large increase in wear rates seen at the second wear transition may result from a thermally induced reduction in yield strength and other material properties.

This improved understanding will help in progressing towards the aim of eventually attaining a wear modelling methodology reliant on material properties rather than wear constants derived from testing.
Availability and use of emergency obstetric services: Kenya, Rwanda, Southern Sudan, and Uganda
Authors: Pearson L. , Shoo R.
Published: January 2005

The article summarises the baseline assessments of emergency obstetric care (EmOC) carried out in Uganda, Kenya, Southern Sudan, and Rwanda in 2003 and 2004.

Objectives

Our objectives were to: (1) set up program baselines on the availability and utilization of EmOC services in these countries; (2) identify gaps and obstacles in providing EmOC services; and (3) make recommendations to governments based on evidence generated.

Methods

Data were collected from clinical record reviews, provider and client interviews, observations, and focus group discussions. Either random or universal sampling was applied in the selection of health facilities assessed. Local nurses and midwives participated in the data collection and, to some extent, data processing and analysis.

Results

The coverage of basic EmOC services ranged 0–1.1/500,000 population compared to the UN‐recommended level of 4/500,000. The coverage of comprehensive EmOC services ranged 0.5–4.3/500,000 compared to the recommended level of 1/500,000. Between 0.6% and 8.8% of all births took place in EmOC facilities, and 2.1% and 18.5% of all expected direct obstetric complications were treated. Cesarean section as a proportion of all births was between 0.1% and 1%. Shortage of trained staff especially mid‐level providers, poor basic infrastructure such as lack of electricity and water supplies, inadequate supply of drugs and essential equipment, poor working conditions and staff morale, lack of communication and referral facilities, cost of treatment, and lack of accountability and proper management were identified as the main obstacles in providing 24‐h quality EmOC services especially in remote and rural areas.

Conclusions

Lack of basic EmOC services limits women's access to life‐saving services during obstetric complications. To reduce maternal mortality ratio the states and development partners need to focus their effort to improve the coverage, quality, and utilization of EmOC services through supportive national policy, effective program strategies, increased budget allocation to maternal health program, rural infrastructure development, and regular monitoring, and evaluation of progress.
Primary mediastinal choriocarcinoma
Authors: Yun E.J. , Chung J.Y. , Han H.S.
Published: January 2005

Although mediastinal choriocarcinoma is very rare, the possibility of choriocarcinoma should be considered in fertile women who have unexplained abnormal chest radiographic findings.
Management of the traumatic oronasal fistula in the cat with a conical silastic prosthetic device
Authors: de Souza Heloisa Justen M , Amorim Fernanda V , Corgozinho Katia B , Tavares Rogério R
Published: January 2005

Management of a traumatic oronasal fistula with a prosthetic device in an 8-year-old male neutered domestic shorthair cat is described. The animal had fallen from a height of three stories at the age of 1 year. The fall had resulted in a fracture of the hard palate and a split in the palatal mucosa. Two surgical attempts to close the defect had been unsuccessful and an autopolymerizable acrylic resin prosthesis had produced unsatisfactory results. The management of the chronic traumatic fistula with a conical prosthetic device was fast, easy and efficient. The device was removed and a second one was put in place after 2 years. This method would appear particularly useful for obturation of large palatal defects that have failed to heal after attempts at surgical closure and is an alternative treatment for debilitated cats which may not be candidates for longer surgical procedures.
Failure to conceive in the queen
Authors: Romagnoli Stefano
Published: January 2005

A 13-month-old Persian queen was presented for infertility. She had been bred on two consecutive oestrous cycles on day 1 of oestrus, and on both occasions had developed a purulent vulvar discharge shortly after breeding. Treatment by the private veterinarian had included parenteral antibiotics and vaginal medications. Upon presentation to the Small Animal Reproduction Service, a complete clinical, diagnostic imaging and laboratory investigation failed to demonstrate evidence of a reproductive tract disease. Therefore, at a subsequent cycle breeding was attempted on day 3 of oestrus. The queen conceived and delivered six kittens by caesarean section. The initial inability of this queen to conceive appears to have resulted from inappropriate management practice.
Use of cyanoacrylate in skin closure for ovariohysterectomy in a population control programme
Authors: Faria Maria Carolina Ferreira , de Almeida Flavya Mendes , Serrão Maria Lúcia , de Oliveira Almeida Núbia Karla , Labarthe Norma
Published: January 2005

N-butyl-cyanoacrylate tissue adhesive was evaluated as a skin closure material in a population control programme. Fifty-two female cats underwent ovariohysterectomy: skin closure of 25 of those cats was undertaken with nylon (3–0) and in 27 with the adhesive. Twenty-three cats spent the postoperative period confined in cages and 29 were free within a 50-square-metre fenced area. The parameters used for evaluation were: dehiscence or secretion and presence and extension of erythema at the surgical site. It was observed that the time required for closure of the surgical site with the adhesive was shorter than with nylon, saving approximately 1 min per animal. The adhesive or conventional suture allowed similar healing, and independent of material used for skin closure or the postoperative exercise, there was no statistical difference in wound cicatrization. As the adhesive eliminates the need for suture removal and decreases surgery time, without additional risk to the cat, it may be indicated for surgical population control programmes.
MRI characteristics of suspected acute spinal cord infarction in two cats, and a review of the literature
Authors: MacKay Amy D. , Rusbridge Claire , Sparkes Andrew H. , Platt Simon R
Published: January 2005

A 10-year-old neutered male Persian cat and a 4-year-old spayed female domestic shorthair (DSH) cat were evaluated for acute-onset severe lateralising tetraparesis and hemiplegia, respectively. Both cats also had left-sided Horner's syndrome. Neurological examination of the cats localised the lesion to cranial to C5 in the Persian and the left cervical intumescence (C6–T2) in the DSH. Physical examinations were otherwise generally unremarkable. Routine laboratory tests and spinal radiography were normal for the Persian cat and were not performed for the DSH cat. A cerebrospinal fluid (CSF) tap was attempted for the Persian cat but aborted because of gross blood contamination, and was not performed for the DSH cat. Magnetic resonance imaging (MRI) of the Persian cat revealed a lesion within the spinal parenchyma at segments C1 to C3 (slightly more left-sided) which was iso- to hypointense on T1-weighted scans and hyperintense on T2-weighted scans, and which enhanced slightly with gadolinium. MRI of the DSH cat revealed a lesion within the spinal parenchyma at segment C7 (predominantly left-sided) which was hypointense on T1-weighted scans and hyperintense on T2-weighted gradient echo scans. Contrast was not administered. The MRI findings in both cases were highly suggestive of acute spinal cord infarction, based upon comparison to human cases. Both cats made full neurological recoveries with supportive treatment only. This paper describes two cases of suspected acute spinal cord infarction in the cat, demonstrates the potential diagnostic value of MRI, and discusses the clinical syndrome of this condition with a brief review of published cases.
Secondary hypothyroidism following head trauma in a cat
Authors: Mellanby Richard J , Jeffery Nic D. , Gopal Matt S , Herrtage Michael E.
Published: January 2005

An 18-month-old female neutered domestic short hair cat was examined because of marked polydipsia and stunted growth following head trauma when it was 8 weeks old. Diagnostic evaluation revealed hyposthenuric urine, low concentrations of thyroid hormone and undetectable thyroid stimulating hormone concentrations which did not rise following thyroid releasing hormone administration. Lateral radiographs of the left and right tibiae revealed incomplete mineralisation of the greater tubercle and open physis. An almost empty sella turcica and a greatly reduced pituitary were visible on magnetic resonance images of the brain. A presumptive diagnosis of secondary hypothyroidism and central diabetes insipidus following head trauma was made.
Diffusion and Heterogeneous Reaction. VII. Effect of Different Catalyst Geometries
Authors: Ablow C. M. , Motz H. , Wise H.
Published: January 2005

Analyses of the diffusive flux of reactants to catalytic walls and end plate of a cylindrical tube are presented for a number of geometries of experimental interest. Specifically, the reactant concentration profiles are examined in a cylinder composed of sections of different catalytic activities. The results of the analysis are applied to some published experimental data for oxygen-atom recombination on metal oxide surfaces. In addition, an analysis is presented of the influence of the surface area of the catalyst on the concentration flux of reactant. This effect is of importance in the evaluation of the catalytic properties of solids from measurements of mass-diffusion gradients.
Thermodynamic Properties of the Cesium—Graphite Lamellar Compounds
Authors: Salzano F. J. , Aronson S.
Published: January 2005

The vapor pressures of the cesium—graphite lamellar compounds in the two-phase regions were measured at temperatures of 400° to 750°C. The Knudsen effusion method, in conjunction with a tracer technique employing cesium-134, was used. Thermodynamic properties were calculated from the data and are discussed in relation to the structures of the cesium—graphite lamellar compounds.
Microwave Spectrum, Structure, Dipole Moment, and Quadrupole Coupling Constants of 1,2,5-Oxadiazole
Authors: Saegebarth E. , Cox A. P.
Published: January 2005

The microwave spectra of the normal species (C2H2N2O) and the C13CH2N2O, C2H2N15NO, C2D2N2O, and C2HDN2O isotopic species of 1,2,5-oxadiazole have been assigned. The value of the inertial defect indicates a planar structure for the molecule. The structural parameters obtained from the isotopic changes in the moments of inertia plus the center-of-mass condition, Σimibi=0, are:  O–N=1.380±0.003 Å, C=N=1.300±0.003 Å, C–C=1.421±0.003 Å, C–H=1.076±0.003 Å,∠NON=110∘24′±20′,∠ONC=105∘49′±20′,∠CCN=108∘59′±20′,∠CCH=130∘10′±35′,∠NCH=120∘51′±35′.Stark-effect measurements gave a dipole moment of 3.38±0.04 D. The nitrogen quadrupole coupling constants of the normal species were determined from an analysis of the hyperfine splittings of four low J Q-branch lines to be: χaa=−0.69±0.09 Mc/sec, χbb=−0.46±0.13 Mc/sec, χcc=1.15±0.04 Mc/sec. These constants correctly predict the shape and splitting of an additional low J R-branch line. The absence of a low-lying vibrationally excited state, the absence of an out-of-plane component of the dipole moment, and the relative intensities of the quadrupole components of the lines of C2H2N2O and C2D2N2O are further evidence for the planarity and C2v symmetry of the molecule.
11B Quadrupole Coupling Tensors in the Hydrated Borates. I. The Tunellite Polyanion
Authors: Cuthbert J. D. , MacFarlane W. T. , Petch H. E.
Published: January 2005

The quadrupolar splitting of the 11B nuclear magnetic resonance signals has been investigated in a single crystal of tunellite, SrO·3B2O3·4H2O. The electric quadrupole coupling constants, eqQ/h, and asymmetry parameters, η, of the electric field gradient tensors at the six unique boron sites were determined to be eqQ/h (kc/sec)ηTetrahedral sites673±20.386±0.004612±20.157±0.006705±20.090±0.007Triangular sites2509±50.093±0.0052503±40.156±0.0032505±40.123±0.004The orientations of the principal axes of the electric field gradient tensors at all boron sites have also been determined.

The NMR results are in agreement with the crystal structure as to numbers and coordinations of the boron atoms and orientation of the planes of the triangularly coordinated boron atoms. The values found for eqQ/h and η at the triangular sites are quite typical, but the eqQ/h values for the tetrahedral sites are significantly higher than normal. This may be due to the fact that the three tetrahedrally coordinated boron atoms are bonded to one oxygen atom in common, a situation which, among the hydrated borates whose structures are known, is unique to the tunellite-type polyanion.
Pressure Shifts in the 23Na Hyperfine Frequency
Authors: Ramsey Alan T. , Anderson L. Wilmer
Published: January 2005

The density shifts of the 23Na ground-state hyperfine frequency have been measured in He, Ne, Ar, Kr, Xe, H2, and N2, giving shifts of 130, 80, 5, −75, −150, 110, and 87 cps/mm of Hg, respectively, pressures being measured at 23°C. The average zero-density hyperfine frequency is 1 771 626 150±250 cps. The temperature dependence of the density shifts has been measured for He, Ne, Ar, and N2.
Antiferromagnetic Structure of AlCr2
Authors: Atoji Masao
Published: January 2005

Body-centered tetragonal AlCr2 has been shown by neutron diffraction to be antiferromagnetic below the Néel temperature of 598°±5°K. The spin structure obtained from the neutron powder data is characterized by an antiferromagnetic coupling between the adjacent Cr layers in the c-layer sequence, Al–Cr ↑ –Cr ↓ –Al–, where each Cr layer forms a ferromagnetic sheet. The magnetic moment of Cr is 0.92±0.02 Bohr magneton and the moment inclines 65±2° from the c axis. Neither crystal nor magnetic transition was observed below 598°K down to 1.6°K. The Debye temperature of AlCr2, 472±8°K, was obtained from the coherent nuclear-scattering data.
Theoretical Study of the Monolayer Adsorption of Argon on a Xenon Surface
Authors: Steele William A. , Kebbekus Earle R.
Published: January 2005

A theoretical analysis is given of a portion of the experimental data of Prenzlow and Halsey on the adsorption of argon on a preadsorbed xenon layer. The potential-energy functions for Ar atoms over a square-packed and a triangular-packed xenon layer on a graphitic substrate are computed, and it is argued that the argon atoms should be highly localized at the experimental temperatures in such a potential field. Consequently, the data are compared with theoretical lattice-gas thermodynamic properties for a square and a triangular lattice and it is shown that better agreement between experiment and theory is found if a square-packed lattice is assumed. The validity of this conclusion and its physical implications are discussed.
Matrix Photolysis Products of Diazomethane: Methyleneimine and Hydrogen Cyanide
Authors: Moore C. Bradley , Pimentel George C. , Goldfarb Theodore D.
Published: January 2005

Photolysis of diazomethane dimers in solid nitrogen produces methyleneimine, H2CNH, and HCN, as shown by infrared spectral study. The HCN frequencies show that it forms a strong hydrogen bond to the imine. Deuterium and 15N isotopic substitutions aid in the vibrational assignment of H2CNH. Normal coordinate analysis indicates that this prototype C=N stretching force constant is (9.3±0.5) × 105 dyn/cm despite difficulties in obtaining a satisfactory fit to all of the observed frequencies.
Periodically Pulsed Nuclear Magnetic Resonance
Authors: Gordon Sidney L. , Baldeschwieler John D.
Published: January 2005

Periodically pulsed single- and double-resonance experiments exhibit a variety of features which should prove useful for detailed relaxation analyses of complex spin systems. Various aspects of the pulsed single-resonance experiments are described using the Bloch equations, including the results of pulsing the receiver in synchronization with the rf field. Periodically pulsed double resonance experiments with a pulsing frequency of the order of the widths of the irradiated lines offer a technique for observing Overhauser intensity effects without double-resonance complications. The method is illustrated for CFHCl2, CF2HCl, and CF3H, and is used to demonstrate explicitly that the Overhauser intensity changes vanish for large irradiation intensities.
Charge Scavenging During the Radiolysis of Liquid Cyclohexane
Authors: Freeman G. R.
Published: January 2005

A reaction mechanism is presented which quantitatively explains the charge-scavenging results of F. Williams in terms of the nonhomogeneous distribution of separation distances of the positive ions from their counterions.
Infrared Spectra of Solid α- and β-Oxygen
Authors: Cairns Bruce R. , Pimentel George C.
Published: January 2005

The spectrum of solid α-oxygen deposited at 15° or 20°K consists of a sharp absorption centered at 1549 cm−1 (half-width ∼4 cm−1) and a more intense, broad absorption (half-width ∼45 cm−1) with well-defined peaks at 1591 and 1617 cm−1. Warming through the α—β phase transition (at 24°K) causes the broad band to become more diffuse. Recooling restores the low-temperature spectrum and shows that the α—β transition is rapid and reversible. Slow deposition at 4°K gives an imperfect solid in which the sharp feature is very much intensified. The broad band is due to combinations involving translational lattice modes; the sharp feature is apparently the O2 fundamental appearing because of lattice imperfections. The β-oxygen spectrum indicates intermolecular force constants of 0.024 and 0.013 mdyn/Å and the α-oxygen spectrum is consistent with a site symmetry of C2h in a space group of C2h1. None of the spectra, including those of isotopic mixtures, suggest the presence of O4 molecules.
On the Griffiths Inequality at a Critical Point
Authors: Rushbrooke G. S.
Published: January 2005

The Griffiths inequality, relating the degree of the phase boundary, degree of the critical isotherm, and order of the temperature divergence of the isochoric specific heat, near the critical point of a fluid, is derived from a thermodynamic equality, and not from an initial inequality derived from convexity properties of the free energy.
Microwave Spectrum and Molecular Structure of Nitrosobenzene
Authors: Hanyu Yoshiaki , Boggs James E.
Published: January 2005

The microwave spectrum of nitrosobenzene has been studied in the frequency region between 13 000 and 24 000 Mc/sec. Numerous a-type, R-branch transitions have been identified, and the rotational constants have been determined. The molecule is completely planar with the C–N=O group bent at an angle of about 116° in the plane of the ring.
High-Pressure Effects on Organic Liquids. II. Infrared Spectra and P—V—T Relationships of Rotational Isomers of Some Halogenated Ethanes
Authors: Brasch J. W.
Published: January 2005

Infrared spectra were obtained of single crystals of various rotamers of a series of halogenated ethanes. The spectrum of the trans rotamer of 1,1,2,2-tetrachloroethane is reported for the first time. P—V—T relationships of rotamers are more complex than was expected, with both polymorphism and solid—solid phase transitions involved.

A new technique for measuring compressibilities at high pressure is described. This technique is used to demonstrate a solidification at constant volume and a solid—liquid equilibrium over a considerable range of pressure.
Second Differential Ionization-Efficiency Curves for Fragment Ions by Electron Impact
Authors: Dorman F. H.
Published: January 2005

A study has been made of the information obtainable from second-differential ionization-efficiency curves for fragment ions produced by electron impact. To aid in the interpretation of the appearance-potential data, measurements were made of the kinetic energy of the fragment ions.

From the second-differential electron-impact curves, it is shown that accurate appearance potentials of many fragment ions cannot be obtained by orthodox methods, e.g., CH3+(C2H6). For a few fragment ions such as CH3+(CH4), it is possible to obtain a valid appearance potential.

The main result of the kinetic-energy retardation studies is that few fragment ions appear to have kinetic energy for electron ionizing energies near to the fragment-ion appearance potential.
Ultrasonic Investigation on Kinetics of Ionic Reaction in Sodium Phosphate Solution
Authors: Yasunaga Tatsuya , Tanoura Mitsuyasu , Miura Masaji
Published: January 2005

The velocity of sound in sodium phosphate solutions has been studied in the frequency range 2.5–6.5 Mc/sec at concentrations varying from 0.01 to 0.25M. The normal dispersion below 0.1M and the abnormal dispersion above 0.11M have been observed. In the former concentration region the dependence of concentration on the relaxation frequency gave the equilibrium constant which was in excellent agreement with that of the hydrolysis of PO43− and made clear the mechanism responsible for dispersion. The corresponding forward and reverse rate constants were calculated using the relaxation time in solution and the dissociation constants of the acid and water at 25°—35°C. The activation energy was also calculated from the temperature dependence of rate constants. The discussion was extended to the effect of dielectric constant and hydrogen-ion concentration on the dispersion.
Time-Dependent Perturbation—Variation Method. III
Authors: Yaris Robert
Published: January 2005

It is shown that by a slight extension of the method previously presented one can use a minimum variational principle for time-dependent perturbational problems instead of the original stationarity principle.
Ferroelectric Structure of BaTiO3 as Revealed by an Electron-Beam Technique
Authors: Yamaguchi S.
Published: January 2005

The two easy polarization axes [001] and [01̄2] were observed for a BaTiO3 crystal of the pseudocubic Perovskite structure. The two types of the Ti–O bond whose atomic distances are 1.97 and 4.44 Å are oriented parallel to these two axes, respectively.
On the Orientation of Nonspherical Particles in an Alternating Electrical Field
Authors: Schwarz Gerhard , Saito Masao , Schwan Herman P.
Published: January 2005

It is shown in general that any nonspherical particle imbedded in a medium with a different complex dielectric constant will experience orienting forces from an impressed alternating electrical field. The direction of stable orientation is determined by the geometry of the particle, by the dielectric properties of the material involved, and also by the frequency of the field. A continuous change of frequency may result in a continuous rotation of the particle as well as in a sudden ``turnover'' covering an angle of 90 deg.

The case of an ellipsoid suspended in an isotropic medium is discussed in more detail. If the complex dielectric constant of the ellipsoid can be represented by a tensor with principal axes coinciding with the geometrical axes, the direction of stable orientation always is given by one of these axes. However, the choice of ``stable axis'' may be frequency dependent, so that turnover effects may occur as the frequency is changed. Such behavior is possible even if the dielectric properties of the ellipsoid are isotropic. Similar effects are displayed by a system approximating the passive electrical properties of biological cells in an electrolyte solution, thus accounting for some unusual experimental observations of this kind.
Passage of ac Through Low-Dielectric-Constant Liquids
Authors: Gavis Jerome
Published: January 2005

The linearized partial differential equation describing transport of electric charge in low-dielectric-constant liquids, developed earlier by the author, is solved for the passage of ac through such liquids between parallel plane electrodes. If the electrode separation is not too small, the current-applied potential relationship obtained from the solution approximates Ohm's law closely when the liquid relaxation time is much shorter than the ac cycle time or, alternatively, when the product of the relaxation time and the frequency is very small. If this is not so, displacement currents causing deviations from Ohm's law appear. Because relaxation times in low-dielectric-constant liquids are often of the order of seconds or even minutes, practical use of ac in the measurement of their conductivities is limited.
Microwave Spectrum and Internal Rotation of Methylthiocyanate
Authors: Nakagawa S. , Takahashi S. , Kojima T. , Lin Chun C.
Published: January 2005

The microwave spectrum of methylthiocyanate has been investigated in the frequency range of 8–34 kMc/sec. The rotational constants determined from the spectrum are A=15 796.2, B=4155.4, and C=3354.2 Mc/sec. From the Stark effect of the low-J lines, the dipole moment is found to be very nearly parallel to the principal a axis with a magnitude of 4.03 D. Splittings due to internal rotation (A—E splittings) are observed for rotational transitions in the ground and in the first excited torsional states. Analysis of these splittings gives an internal barrier of 556 cm−1. Two sets of vibrational satellite lines are found for all the low-J transitions. They are believed to be associated with the first two excited states of a bending vibrational mode of frequency about 160 cm−1. A structure of the molecule which is consistent with the rotational constants is C–H=1.093 Å, ∠HCH=109°28′, C–S (CH3–S)=1.820 Å, C–N=1.156 Å, S–C=1.684 Å, and ∠CSC=99°52′.
Dynamic Nuclear Polarization by Asphaltene Radicals: Effects of Colloid Size and Solvent Diffusion
Authors: Poindexter Edward H.
Published: January 2005

Dynamic proton polarization in colloidal asphalt solutions arises from electron—proton dipolar coupling. At 75 G, the dipolar interaction is modulated by colloid-tumbling motions and solvent-molecular diffusion. The NMR signal enhancement declines much more slowly with increasing magnetic field than would be predicted from a single correlation time appropriate to colloid tumbling. The observed decline suggests a dual-motion model in which radical tumbling controls the low-frequency transitions, and solvent diffusion controls the high-frequency transitions. The low-frequency transitions dominate proton relaxation. The enhancement and proton relaxation rate are observed to vary by more than an order of magnitude in a series of monoalkylbenzene solutions with a viscosity range of five to one. Enhancement declines with colloid flocculation in less-effective solvents; relaxation rate increases. In all cases, the individual low- and high-frequency transition rates are in accord with the dual-motion model.
On the Nonlinear Dielectric Behavior of Desoxyribonucleic Acid Fibers at Low Frequencies
Authors: Brot C. , Lassier B. , Sharbaugh A. H. , Reynolds S. I. , White D. M.
Published: January 2005

The dielectric behavior of moist desoxyribonucleic acid fibers at low frequencies has been studied, and is explained phenomenologically. This behavior is nonlinear with respect to the thickness of the sample and to the applied voltage. The experimental results can be reproduced if the conductance of the sample is approximated by a constant term plus a term increasing with the applied voltage. Consequently, at low voltage the behavior appears linear with respect to the voltage, but still depends upon the thickness of the sample; the conductance and capacitance per unit area of electrode are the important quantities. Under this condition (low voltage) a region of absorption has been found, with a critical frequency of 0.014 cps at 25°C and very large apparent dielectric constant (ε′≈105). This behavior is interpreted as being due to the formation of an ionic double layer at the electrodes. The nonlinear phenomenon is attributed to the fact that with increased voltage the electrodes become less blocking.
Interpretation of Cyclotron Resonance Line Shapes in Slightly Ionized Gases
Authors: Fehsenfeld Fred C. , Megill Lawrence R. , Droppleman LeAnn K.
Published: January 2005

The cyclotron resonance line shape for the absorption of microwave power by electrons in a slightly ionized gas is analyzed in terms of the energy dependence of the electron-collision frequency for three different electron energy distribution functions. These calculations also include results using measured collision frequencies for collisions between electrons and four netural gases, helium, argon, nitrogen, and oxygen. Moreover, the effects on the deduced collision frequency caused by the presence of admixed broadening agents such as ions is investigated. Because the line shape is strongly influenced by the energy dependence of the collision frequency, the calculation of collision frequencies from linewidth data requires an accurate knowledge of the variation of collision frequency with energy. The examples which are given indicate that extreme care must be exercised if reliable interpretations of experimental data are to be obtained.
Single-Particle Theory for Systems at High Densities. II. Solid Argon and Argon—Quinol Clathrate
Authors: Hillier Ian H. , Walkley John
Published: January 2005

A quantal version of the Lennard-Jones and Devonshire cell theory is used to predict the thermodynamic properties of solid argon and argon in a β-quinol matrix at low temperatures. The agreement with the experimental properties of solid argon is very good and an interpretation of the specific heat contribution due to cavity formation is discussed. The comparison with the argon—quinol clathrate data is not good. Reasons for this discrepancy are discussed and krypton— and methane—quinol clathrates are examined.
Proton Magnetic Resonance Shifts in Aqueous Solutions of Paramagnetic Metal Ions
Authors: Luz Z. , Shulman R. G.
Published: January 2005

The nuclear magnetic resonance of the water proton in aqueous solutions of paramagnetic metal ions is shifted by the isotropic hyperfine interaction AI·S with the electron spin of the metal. These shifts have been measured for solutions of Cr3+, Fe3+, Mn2+, Co2+, Ni2+, and Cu2+ between 0° and 100°C. Complete averaging of the shift due to rapid exchange of H2O in and out of the solvation shell occurred for Co2+, Cu2+, and Mn2+. However, the averaging of the shift was not complete for Cr3+, Fe3+ (and possibly Ni2+) and the kinetic parameters for the exchange process had to be considered in order to evaluate A.

From the temperature dependence of the proton shifts in Cr3+ and Fe3+ solutions, we determined the pseudo first-order rate constants k and the activation energies ΔE for the proton exchange between solvation shell and bulk. These values are: 8.7×104 sec−1 and 7.5 kcal mole−1 for Cr3+, 2.8×106 sec−1 and 12.1 kcal mole−1 for Fe3+. The proton exchange reaction proceeds via the acid dissociation of the hydrated ions.

From the measured values of A which are all positive, it is shown that the interaction arises from d electrons in dxy, dxz, and dyz, which can only form π bonds with the oxygen of the water. The π bonding is able to proceed via two orbitals on the water, one in the H2O plane and one perpendicular to it. These two orbitals transfer spin to the hydrogen 1s orbitals with similar efficiency but opposite sign, the dominant path being through the orbital in the plane. Following McDonald and Phillips, it is shown how the water proton shifts can be used to measure the number of sites in the first hydration shell of Co2+ which are occupied by H2O. For Co2+ bound to inorganic phosphates or to RNA, this number is five, indicating that Co2+ in these complexes makes only one bond at a time to RNA or to inorganic phosphates.
Thermodynamics of the Dimerization and Trimerization of Gaseous Tungsten Trioxide and Molybdenum Trioxide
Authors: Norman J. H. , Staley H. Gene
Published: January 2005

A mass-spectrometric investigation of gaseous tungsten oxides has yielded the thermodynamic values ΔH°1800=−127 kcal/mole and ΔS°1800=−40±1 eu for 2 WO3(g)=W2O5(g), and ΔH°1800=−240 kcal/mole and ΔS°1800=−77±3 eu for 3 WO3(g)=W3O9(g). The experiments were conducted at reduced activity of WO3 to increase the relative proportion of monomer in the gas phase and permit simultaneous measurement of partial pressures of WO3, W2O6, and W3O9. The activity was reduced by dissolution of tungsten oxide in a molten silicate. Use of similar techniques in studies of gaseous molybdenum oxides yielded ΔH°1800=−112 kcal/mole for 2 MoO3(g)=Mo2O6(g) and ΔH°1800=−209 kcal/mole for 3 MoO3(g)=Mo3O9(g).
Vibrational Excitation of Diatomic Molecules by Electron Impact
Authors: Breig Edward L. , Lin Chun C.
Published: January 2005

Vibrational excitation cross sections of diatomic molecules have been calculated using the Born approximation by including the polarization interaction between the incident electron and the molecule. Because of the divergence of the polarization potential at the origin, a cutoff procedure must be used. Four different cutoff methods have been examined, and the excitation cross sections are not very sensitive to the choice of the cutoff parameters. For the nonpolar molecules, inclusion of the polarization term increases the cross sections by an order of magnitude or more over the previous calculations, while in the case of the CO molecule, the contribution from the polarization term is comparable to that from the monopole—dipole interaction.
Higher-Order Centrifugal-Distortion Effects in Asymmetric Rotators
Authors: Chung K. T. , Parker Paul M.
Published: January 2005

The terms of the general molecular vibration—rotation Hamiltonian that are of the sixth power in the angular-momentum components are studied. Those terms which are expected to contribute to the allowed energies in fourth order of approximation in the Nielsen—Amat—Goldsmith formulation are compiled. Nonlinear triatomic molecules are discussed as a special case.
Centrifugal-Distortion Coefficients of the Nonlinear XYX Molecule
Authors: Chung K. T. , Parker Paul M.
Published: January 2005

All coefficients of centrifugal distortion that are expected to contribute to the molecular vibration—rotation energies to fourth or lower orders of approximation are calculated for the nonlinear XYX molecule as functions of the fundamental molecular constants. The Nielsen—Amat—Goldsmith expansion of the vibration—rotation Hamiltonian forms the basis of this calculation.
Equation for the Refractive Index of Water
Authors: Eisenberg Henryk
Published: January 2005

The observations that β−1 (∂ lnf/∂P)T=B is a constant (of order unity, independent of temperature), and —γ−1 (∂ lnf/∂T)P=B+Cγ−1, lead to an equation f(n)≡(n2−1)/(n2+2)=AρB exp(−CT),which describes the refractive index n of water between 0° and 60°C (at any given wavelength in the visible spectrum) to within a few digits in the seventh decimal. Here ρ is the density, β=(∂ lnρ/∂P)T and γ=—(∂ lnρ/∂T)P. The constant C=—(d lnf/∂T)V reflects the change in the structure of water at different temperatures. The temperature of maximum index [(∂n/∂T)P=0] corresponds to γ=—C/B, and the minimum in the Lorenz—Lorentz specific refraction (n2−1)/(n2+2)ρ corresponds to γ=C/(1—B). The values of the parameters A, B, and C are independent of pressure up to 1100 bar in the temperature range examined. It is suggested that refractive index, or dielectric, measurements at higher pressures and temperatures may yield further information on the structure of water in terms of specific models related to the variation of B and C with the variables of state.