bluuebunny/crossref_metadata_2025 huggingface dataset:
Tramadol/Acetaminophen Combination Tablets for the Treatment of Pain Associated with Osteoarthritis Flare in an Elderly Patient Population
Authors: Rosenthal Norman R. , Silverfield Joel C. , Wu Shu‐Chen , Jordan Donna , Kamin Marc ,   on behalf of the CAPSS‐105 Study Group
Published: December 2004

Objectives: To evaluate the efficacy and safety of adding tramadol 37.5 mg/acetaminophen (APAP) 325 mg combination tablets (tramadol/APAP) to existing therapy for painful osteoarthritis (OA) flare in a subset of elderly patients.

Design: Randomized, double‐blind, placebo‐controlled, 10‐day add‐on study.

Setting: Thirty outpatient centers.

Participants: Of 308 patients with painful OA flare, a subset of 113 patients aged 65 and older.

Measurements: Average daily pain intensity and pain relief scores for Days 1 through 5 and secondary quality‐of‐life measures and medication assessments.

Methods: Patients received one or two tramadol/APAP tablets or placebo four times per day for 10 days during ongoing nonselective or cyclooxygenase (COX)‐2–selective nonsteroidal antiinflammatory drug (NSAID) therapy.

Results: Tramadol/APAP (n=69) was significantly superior to placebo (n=44) for average daily pain intensity (P=.034) and pain relief (P=.010) for Days 1 through 5 and Days 1 through 10 (P=.012 and P=.019, respectively). Tramadol/APAP had significantly better investigator (P<.001) and patient (P=.001) overall medication assessments and significantly better scores on three of four Western Ontario and McMaster Universities Osteoarthritis Index measures (P≤.027). Most common adverse events with tramadol/APAP were nausea (18.8%), vomiting (13.0%), dizziness (11.6%), and constipation (4.3%), with an incidence similar to that of the overall study population. Mean daily dose of tramadol/APAP was 4.5 tablets (168 mg/1,458 mg).

Conclusion: Tramadol/APAP add‐on therapy effectively managed painful OA flare in this elderly subset and was generally well tolerated.
Research Agenda‐Setting Program for Geriatric Ophthalmology
Authors: Lee Andrew G. , Coleman Anne L.
Published: December 2004

The healthcare needs of an aging population of “baby boomers” (persons born between 1946 and 1964) will disproportionately affect ophthalmology. To meet this emerging need, the American Geriatrics Society and the John A. Hartford Foundation developed a research agenda‐setting process for geriatric ophthalmology. A systematic literature search was performed using Medline from the years 1990 to 2000. The literature review (168 papers) was performed to determine the current state of information regarding selected issues in geriatric ophthalmology. A needs assessment for each of the identified topics was performed, gaps in the existing knowledge base were identified, and key questions for future research were proposed. A research agenda‐setting process for geriatric ophthalmology might provide a structural framework for future research efforts in the field.
Patterned grafting of polymer brushes onto flexible polymer substrates
Authors: Padeste Celestino , Solak Harun H. , Brack Hans-Peter , Slaski Michal , Gürsel Selmiye Alkan , Scherer Günther G.
Published: December 2004

Selective exposure of polymer substrates to extreme ultraviolet (EUV) radiation followed by graft polymerization of a second polymer is used to create patterns of polymer brushes. A key feature of this additive structuring process is the possibility to combine the properties of a polymer substrate in precisely predefined regions with the properties of the grafted material. Styrene brushes were grafted onto poly(ethylene-alt-tetrafluoroethylene) (ETFE) substrates after exposure to synchrotron EUV radiation in an interference lithographic setup. The grafted chains are covalently bound to the surface, which allows physical or chemical post-processing without deterioration of the grafted structures.
Effect of spontaneous and piezoelectric polarization on intersubband transition in AlxGa1−xN–GaN quantum well
Authors: Li J. M. , Lü Y. W. , Li D. B. , Han X. X. , Zhu Q. S. , Liu X. L. , Wang Z. G.
Published: December 2004

A self-consistent solution of conduction band profile and subband energies for AlxGa1−xN–GaN quantum well is presented by solving the Schrödinger and Poisson equations. A new method is introduced to deal with the accumulation of the immobile charges at the AlxGa1−xN–GaN interface caused by spontaneous and piezoelectric polarization in the process of solving the Poisson equation. The effect of spontaneous and piezoelectric polarization is taken into account in the calculation. It also includes the effect of exchange-correlation to the one electron potential on the Coulomb interaction. Our analysis is based on the one electron effective-mass approximation and charge conservation condition. Based on this model, the electron wave functions and the conduction band structure are derived. We calculate the intersubband transition wavelength λ21 for different Al molar fraction of barrier and thickness of well. The calculated result can fit to the experimental data well. The dependence of the absorption coefficient α on the well width and the doping density is also investigated theoretically.
Formation of GaN films by Ga ion direct deposition under nitrogen radical atmosphere
Authors: Toda Masaya , Yanagisawa Junichi , Gamo Kenji , Akasaka Yoichi
Published: December 2004

Formation of hydrogen-free gallium nitride (GaN) thin layers by ion beam direct deposition method under nitrogen ambient was investigated. After a Ga ion beam at an energy of 100eV was irradiated on a chip of a Si(111) wafer under a nitrogen gas pressure of 2×10−4Torr using a tungsten hot filament, the composition and the chemical bonding nature of the deposited materials were investigated by x-ray photoelectron spectroscopy (XPS). Although the deposited material using a filament power of 250W showed almost the metallic gallium nature, the XPS spectra of the deposited Ga using the hot filament at a power of 300W was very similar to that of an epitaxially grown GaN reference, indicating the possibility of the formation of GaN thin layer using the present method. Because the pure N2 gas was used as the nitrogen source, no impurity fragments should be incorporated in the deposited materials. As a result, it is shown that the formation of hydrogen-free GaN layers is possible by Ga ion beam direct deposition under nitrogen atmosphere using N2 gas and the hot filament.
Predicting air entrainment due to topography during the filling and scanning process for immersion lithography
Authors: Wei A. , El-Morsi M. , Nellis G. , Abdo A. , Engelstad R.
Published: December 2004

Current optical lithography methods are nearing theoretical limits that prevent their use in the production of circuits for future nodes. A proposed solution is to increase the index of refraction of the transmission medium between the final lens of the exposure system and the wafer. When a liquid is used in this lens–wafer gap, the process is known as immersion lithography. A major concern is air bubbles in the liquid, since they are sources of index discontinuities. This article investigates the potential for trapping air as the free surface of the fluid front moves over features associated with wafer topography during the filling and scanning process. Optical simulations have shown that even very small bubbles located near or on the resist can significantly impact the imaging process. Therefore, the ability to predict the characteristics of the flow, liquid, and features that lead to air entrainment during filling is important. Modeling techniques were developed in order to create models that were capable of resolving the flow characteristics over 100nm scale features without the need to simulate the entire macroscopic flow through the lens–wafer gap. Results of these models show that bubble formation occurs only for extreme geometries and flow conditions. In actual production the velocities, contact angles, and feature profiles are well out of these extreme ranges, and will not cause bubble formation.
Electron beam stimulated field-emission from single-walled carbon nanotubes
Authors: Nojeh Alireza , Wong Wai-Kin , Yieh Eric , Pease R. Fabian , Dai Hongjie
Published: December 2004

Carbon nanotubes are good candidates for electron field- and photo-emitters at the nanoscale since their sharp geometries lead to significant external field enhancement. Also, their mechanical strength and structural completeness alleviate issues related to stability and lifetime that may be present in small-scale emitters that have loose atoms at their tips. Here, we demonstrate how an external electron beam can stimulate electron emission from the tip of a nanotube that is lying on an insulating surface and is subject to an external electric field, thus making it act as an electron bombardment source.
Negative electron affinity group III-nitride photocathode demonstrated as a high performance electron source
Authors: Machuca Francisco , Liu Zhi , Maldonado J. R. , Coyle S. T. , Pianetta P. , Pease R. F. W.
Published: December 2004

The need for a high performance (low energy spread <0.5eV, long lifetime >3months per spot, emission stability <1%∕h) electron source continues as part of the development of new e-beam writing and inspection tools. We present measurements from a group III-nitride (indium gallium nitride) photocathode in a demountable vacuum system to measure energy spread, lifetime, and preliminary blanking effects. We show the results of cathodes operating in ultrahigh vacuum (UHV), high vacuum (HV), and oxygen-rich backpressures. Our results show InGaN has a longitudinal energy spread of <300meV in reflection mode, flat lifetimes of 60h per illuminated spot where the yield changes by <10%, and stable emission with typical recoveries within 99% of original photocurrent for all blanking periods and vacuum conditions tested (0.5to10min periods).
Nanoscale electronics based on two-dimensional dopant patterns in silicon
Authors: Shen T.-C. , Kline J. S. , Schenkel T. , Robinson S. J. , Ji J.-Y. , Yang C. , Du R.-R. , Tucker J. R.
Published: December 2004

A nanoscale fabrication process compatible with present Si technology is reported. Preimplanted contact arrays provide external leads for scanning tunneling microscope (STM)-defined dopant patterns. The STM’s low energy electron beam removes hydrogen from H terminated Si(100) surfaces for selective adsorption of PH3 precursor molecules, followed by room temperature Si overgrowth and 500 °C rapid thermal anneal to create activated P-donor patterns in contact with As+-implanted lines. Electrical and magnetoresistance measurements are reported here on 50 and 95 nm-wide P-donor lines, along with Ga-acceptor wires created by focused ion beams, as a means for extending Si device fabrication toward atomic dimensions.
At-wavelength alignment and testing of the 0.3 NA MET optic
Authors: Goldberg Kenneth A. , Naulleau Patrick P. , Denham Paul E. , Rekawa Senajith B. , Jackson Keith , Anderson Erik H. , Liddle J. Alexander
Published: December 2004

Extreme ultraviolet (EUV) interferometry has been successfully performed for the first time at 0.3 numerical aperture (NA). Extensive EUV “at-wavelength” testing including alignment, was performed on a newly created Micro Exposure Tool (MET) optic designed for sub-50-nm EUV lithographic imaging experiments. The two-mirror, 0.3 NA MET is among the highest resolution light-projection lithography tools ever made. Using both lateral shearing and phase-shifting point-diffraction interferometry, the wavefront was measured across the field of view, and the alignment was optimized in preparation for imaging. The wavefront quality reached 0.55nm RMS (λEUV∕24.5) in a 37-term annular Zernike polynomial series, dominated by higher-order spherical aberration. Measurements included calibrations of the interferometer accuracy, assessment of repeatability, and cross-comparisons of visible and EUV interferometric measurements.
Fabrication of metallic nanostructures by atomic force microscopy nanomachining and lift-off process
Authors: Hsu Ju-Hung , Lin Chun-Yu , Lin Heh-Nan
Published: December 2004

We report the fabrication of metallic nanostructures by atomic force microscopy nanomachining on a thin resist and subsequent metal coating and lift-off. Nanodots with a size of 70nm, nanowires with a width of 120nm, and nanoelectrodes with a gap of 50nm have been successfully created. Theoretical estimates of the minimum force for a satisfactory lift-off are also given and found to be consistent with the experimental value. The present work demonstrates the feasibility and effectiveness of using a single-layer resist in comparison with a two-layer resist.
Particle adhesion and removal mechanisms during brush scrubber cleaning
Authors: Xu K. , Vos R. , Vereecke G. , Doumen G. , Fyen W. , Mertens P. W. , Heyns M. M. , Vinckier C. , Fransaer J.
Published: December 2004

Brush scrubbers are among the most commonly used instruments for wafer-cleaning applications nowadays. However, the removal mechanisms of nanosized particles are far from clear, especially because no direct experimental data are available to backup theoretical models in the literature. This study combines a theoretical approach based on a force analysis with an experimental study of the removal of nanosized slurry particles. In the theoretical part, all forces affecting the adhesion and the removal of particles are evaluated to determine which are dominant in two extreme removal mechanisms: lifting and rolling. In the experimental part, the removal efficiency of 34nm SiO2 particles is investigated by using the haze approach. Based on a study of the aging of contaminated wafers, conditions are selected where no chemical bonds are formed between a particle and a substrate. Force analysis and experimental observations both show that nanosized particles cannot be lifted directly by a brush. Instead, rolling should be the main particle-removal mechanism. The average fluid film thickness between brush and wafer surface is determined based on power measurements of the brush motor and a friction analysis, indicating that the system is in a hydrodynamic lubrication regime across a wafer in average. In this frame, results also show that the hydrodynamic drag force is the dominant removal force for nanosized particles.
244-nm imaging interferometric lithography
Authors: Frauenglass A. , Smolev S. , Biswas A. , Brueck S. R. J.
Published: December 2004

Imaging interferometric lithography, combining off-axis illumination, multiple exposures covering different regions of spatial frequency space, and pupil plane filters to ensure uniform frequency-space coverage, is a relatively new imaging concept that provides an approach to accessing the fundamental, linear-systems-resolution limits of optics. With an air medium between the lens and the wafer, the highest spatial frequency available with 244-nm exposure tool with a numerical aperture of 0.9 corresponds to a half-pitch of 68-nm. Allowing for ∼10% subbands above this central frequency, this suggests that ∼75-nm half-pitch patterns should be accessible. A 22× reduction imaging interferometric lithography testbed demonstration of printing a non-periodic (arbitrary) 86-nm half-pitch pattern is reported. This result was achieved with a simple chrome-on-glass mask without the use of any mask-based resolution-enhancement techniques such as phase-shift or optical proximity correction. Scaling this result to a 193 nm wavelength and an immersion numerical aperture of 1.3 directly addresses the 45-nm half-pitch node.
Detection of bacterial cells and antibodies using surface micromachined thin silicon cantilever resonators
Authors: Gupta Amit , Akin Demir , Bashir Rashid
Published: December 2004

This article describes a surface micromachined cantilever beam-based resonator for biological sensing applications. The study used a novel microfabrication technique of merged epitaxial lateral overgrowth (MELO) and chemical mechanical polishing (CMP) to fabricate thin, low stress, single-crystal silicon cantilever beams. The vibration spectra of the cantilever beams, excited by thermal and ambient noise, was measured in air using a Dimension 3100 Series scanning probe microscope (SPM), and in certain cases, a Polytec MSV300 laser Doppler vibrometer. The sensors were used to detect the mass of Listeria innocua bacteria by applying increasing concentration of bacteria suspension on the same cantilever beams and measuring the resonant frequency changes in air. Cantilever beams were also used to detect the mass of proteins such as Bovine Serum Albumin (BSA) and antibodies for Listeria that were attached to the cantilever’s surfaces by physical adsorption; following which they were used to capture and detect the mass of the bacterial cells on the functionalized cantilever beam surfaces’. The effects of critical point drying of the proteins were evaluated and the results indicate that the functionality of the antibodies was not reduced once rehydrated after critical point drying. The developed biosensor is capable of rapid and ultrasensitive detection of bacteria and promises significant potential for the enhancement of microbiological research and diagnostics.
Fabrication of 1D and 2D vertical nanomagnetic resonators
Authors: Zhang Shuang , Fan Wenjun , Minhas B. K. , Frauenglass A. , Malloy K. J. , Brueck S. R. J.
Published: December 2004

We have successfully fabricated the first resonant magnetic nanostructures exhibiting a negative permeability in the midinfrared. These metal-dielectric structures exhibit local resonances based on metallic inductive-capacitive effects that are controlled by the dimensions of the individual nanostructures and are independent of the periodicity, which is much smaller than the resonance wavelengths. Compared to other commonly used structures for obtaining negative permeability in the microwave and THz regions which are based on a planar fabrication paradigm, this structure is oriented vertically so that the smallest features are controlled by deposition rather than by lithography.
Nonaqueous development of silsesquioxane electron beam resist
Authors: Schmid Gerard M. , Carpenter Leslie E. , Liddle J. Alexander
Published: December 2004

While the primary use of hydrogen silsesquioxane (HSQ) is as a dielectric in microelectronics fabrication, this material is also capable of forming high resolution, negative-tone features with low roughness when patterned with an electron beam. Unfortunately, under common processing conditions HSQ is relatively insensitive to electron beam exposure; poor reproducibility has also been observed. HSQ postexposure processing typically consists of development via immersion in an industry-standard aqueous solution of base, followed by rinsing with water or isopropanol. While other resist materials have been specifically designed for compatibility with aqueous base processing, HSQ is known to be chemically unstable in the presence of base. We report that several organic solvents that are not reactive towards HSQ are less aggressive at removing the exposed regions of the film. As a result, it is possible to successfully image HSQ with markedly reduced exposure dose. The considerable difference in exposure dose can be largely attributed to the difference in reactivity toward HSQ between organic solvents and aqueous base, but other factors must also be considered. For example, HSQ structures can be formed at low doses when developed with isopropanol, but the structures are very rough and irregular. This paper reports an alternative approach to HSQ processing that provides insight into mechanistic phenomena while offering certain advantages over standard processing techniques.
Polyvinyl alcohol templates for low cost, high resolution, complex printing
Authors: Schaper Charles D. , Miahnahri Alan
Published: December 2004

Templates for imprint lithography and MxL (molecular transfer lithography) are generated by adhesion of a spin-cast film of polyvinyl alcohol (PVA) to a carrier comprised of materials selected for conformability or distortion reduction. Template formation using both polymeric carrier materials and rigid materials, including quartz and glass carrier materials, is demonstrated. The absence of a carrier material altogether to form a suspended thin film is shown to be feasible. The rigid template material is formed by bonding the PVA patterned film to a rigid carrier while still connected to the master pattern, and it is demonstrated that separation occurs at the PVA-silicon master pattern interface. Form factors for the templates include a 25mm×25mm patterned film attached to a 65mm×65mm glass substrate, a full 100 mm pattern bonded to a quartz substrate, and a 100 mm mask of Mylar™ bonded with a patterned PVA film for MxL applications. These carrier materials are developed in a form factor compatible with commercial nanoimprint lithography tools, and for standard contact aligners adapted to perform MxL processing.
Synthesis, Characterization, and Boron Uptake of Organic–Inorganic Hybrid Mesoporous Materials
Authors: Wang Lina , Qi Tao , Zhang Yi
Published: December 2004

An organic–inorganic hybrid mesoporous material with polyol functional groups has been prepared by a two-step post-grafting method using mesoporous SBA-15 as the support, proven to be a promising adsorbent with the considerable uptake capacity, as well as the high selectivity towards boron.
Biosensoren
Authors: Schmid Rolf D. , Bilitewski Ursula
Published: December 2004

Im internationalen Sprachgebrauch zählt eine Enzymelektrode zu den „Biosensoren”︁, ein Bildanalysator zur Tumordiagnose dagegen nicht, und bei einem Fließinjektionssystem mit immobilisiertem Enzym gehen die Meinungen auseinander. Der Begriff „Biosensor”︁ war lange Zeit nicht streng definiert. Es handelt sich jedoch immer um ein Analysengerät, und meist wird der Begriff für einen Aufbau verwendet, in dem eine biologische Komponente (z. B. ein Enzym, ein Antikörper oder ein Mikroorganismus) unmittelbar mit einem Signalwandler (z. B. einer Elektrode, einer optischen Faser oder einem Piezokristall) verbunden ist.
Antikörper. Wie die Natur eine chemische Struktur beliebig variiert
Authors: Grawunder Ulf , Haasner Dirk
Published: December 2004

Antikörper haben zentrale Bedeutung für die spezifische Immunreaktion aller Wirbeltiere. Charakteristisch für diese Gruppe von Glykoproteinen ist, daß sie beliebig viele verschiedene Strukturen bilden kann, die zu einer praktisch unbegrenzten Anzahl von Antigenen chemisch komplementär sind. Als Antigene bezeichnet man alle Substanzen, die an Antikörper binden können. Dabei kann es sich sowohl um Moleküle biologischer Herkunft als auch um synthetische Stoffe handeln, selbst wenn diese im Verlauf der biologischen Evolution nie existiert haben. Die molekularen Mechanismen, mit deren Hilfe die Natur einer derart unerschöpflichen Menge von potentiell gefährlichen Antigenen eine ebenso große Anzahl von spezifischen Antikörpern entgegensetzt, sind das Thema des folgenden Artikels.
Blei‐ und Kupfergewinnung im Rahmen eines anorganischen Praktikums
Authors: Wiskamp Volker , Lüdtke Harald , Gruehn Reginald
Published: December 2004

Die beschriebenen Versuche vermitteln Studenten nicht nur anspruchsvolle analytische und präparative anorganische Chemie, sondern auch ein tieferes Verständnis für die Denkweise in der chemischen Industrie. Eine Produktion kann nur gestartet werden, wenn die Qualität der Rohstoffe gesichert ist, und deshalb ist deren Eingangskontrolle zwingend erforderlich. Das Verfahren selbst muß den Belangen des Umweltschutzes Rechnung tragen. Schadstoffemissionen in Luft und Wasser sind verboten und entsprechende Gegenmaßnahmen zu treffen. Schließlich steht und fällt ein Herstellungsverfahren mit der Ausbeute und Qualität des erzeugten Produktes. Erst wenn ein Produkt die geforderte Spezifikation erfüllt, darf es für den Verbrauch freigegeben werden. Und so, wie in der chemischen Industrie das Verursacherprinzip gilt, nach dem der Produzent für seine Produktion und seine Produkte haftet, haben sich auch die Studenten um die fachgerechte Aufbereitung aller anfallenden Versuchsreste zu kümmern.
Chemie in 30 Jahren
Authors: Jaenicke Lothar , König Horst , Herberhold Max , Boche Gernot , Wambach Heinz , Hensel Friedrich , Janoschek Rudolf
Published: December 2004

„ChiuZ”︁ wird 30 Jahre alt! Runde Geburtstage sind nicht nur Grund zum Feiern; die Jubilare nehmen sie auch oft zum Anlaß, um einerseits Bilanz zu ziehen und um andererseits über Gegenwart und Zukunft nachzudenken. Wir haben nun unsere Kuratoren gebeten, einmal aus ihrer Sicht mögliche Entwicklungslinien aufzuzeigen und zu kommentieren, natürlich immer eingedenk der Warnung Niels Bohrs: „Prognosen sind schwierig, besonders wenn sie die Zukunft betreffen.”︁ Doch lesen Sie selbst!.
Synthesen von Mannich‐Basen von Hydroxy‐indolen. 3. Mitteilung über synthetische Indol‐Verbindungen [1]
Authors: Troxler F. , Bormann G. , Seemann F.
Published: December 2004

The reactivity of hydroxy‐indoles under the conditions of the Mannich‐reaction has been studied. The electrophilic side‐chain enters in each case in a position ortho to the phenolic group. 4‐Hydroxy‐indole is substituted in the 5‐, 5‐hydroxy‐indole in the 4‐, 6‐hydroxy‐indole in the 7‐, and 7‐hydroxy‐indole probably in the 6‐position. The structures of the Mannich bases from 4‐, 5‐ and 6‐hydroxy‐indole have been confirmed by comparison of the hydroxy‐methyl‐indoles obtained by reductive desamination with hydroxy‐methyl‐indoles prepared by unambiguous total synthesis.
Untersuchungen über das Verhalten organischer Mischphasen. 6. Mitteilung. Dampfdrücke, Dichten, thermodynamische Mischungsfunktionen und Brechungsindices des binären Systems Methanol‐Diäthyl‐äther bei 25°
Authors: Arm H. , Bankay D.
Published: December 2004

The total vapor pressures, the heats of mixing, and the refractive indices of the system methanol‐diethyl ether were measured at 25°C. The density was used to determine concentrations for the total pressure measurements. The partial pressures, activity coefficients, excess free energies, entropy functions, and excess volumes were calculated.
Die Molrefraktion von Aquo‐Ionen metallischer Elemente und die Auswertung von Lichtbrechungsmessungen in der anorganischen Chemie
Authors: Salzmann Jean‐Jacques , Jørgensen Christian Klixbüll
Published: December 2004

It is shown that molar polarisabilities α of aqueous solutions of electrolytes previously measured by HEYDWEILLERand other authors, and here of lanthanide (III) and bismuth (III) perchlorates, can be brought in much better agreement with α values for crystalline substances than usually thought, and that additivity of α for each constituent is a remarkably good approximation, except in the case of complexes having very intense electron transfer bands. In an isoelectronic series, α normally decreases from M(I) to M(II) but frequently increases in direction of M(III) and M(IV). The oscillator strength and contributions from inner shells are discussed, and an effect of half‐filled shells on excitation energies pointed out.
Die Kristallstruktur von H3Co(CN)6
Authors: Güdel H. U. , Ludi A. , Bürki H.
Published: December 2004

The crystal structure of the hexagonal H3Co(CN)6 (a = 6.43 Å, c = 5.70 Å, Z = 1) has been determined by X‐ray powder methods. The space group is D (at least pseudo), the cobalt atoms being in (0, 0, 0). Structure factor calculations lead to a final R‐value of 13.2%, based on F2‐sums of coinciding reflections. The carbon and nitrogen atoms are located at the vertices of a slightly distorted octahedron around the cobalt atom; the angle CoCN is 177°. The interatomic distances are: CoC = 1.89 Å, CoN = 2,98 Å, CN = 1.09 Å. The pseudo‐octahedral units of Co(CN)6 are linked together by NHN bridges. Infrared spectra show that the most probable linkage is the one with a NHN‐bond length of 2.7 Å.
5‐Schwefelsubstituierte 1,2‐Dithiol‐3‐one
Authors: Bader JÖRg
Published: December 2004

1, 2‐Dithioles with sulfur substitutents in position 5 are prepared by reaction of 4‐chloro‐1, 2‐dithiol‐3‐ones with thiols, sulfinates, dithiocarbamates, or potassium ethylxanthate. Bis‐(4‐chloro‐1, 2‐dithiol‐3‐on‐5‐yl) sulfide is produced from 4, 5‐dichloro‐1, 2‐dithiol‐3‐one with sodium thiosulfate and other thiol forming reagents. The 5‐alkylthio‐ and 5‐arylthio‐1, 2‐dithiol‐3‐ones can be oxidized with peracids to sulfoxides and, partly, to sulfones; the sulfones can also be obtained from sulfinates. 4‐Chloro‐5‐(α‐methyl‐benzylthio)‐1, 2‐dithiol‐3‐one reacts differently with peracetic acid, giving bis‐(4‐chloro‐1, 2‐dithiol‐3‐on‐5‐yl) disulfide besides 4‐chloro‐1, 2‐dithiol‐3‐one. With oxalyl chloride, 4‐chloro‐5‐alkylthio‐1, 2‐dithiol‐3‐ones form 3, 4‐dichloro‐dithioliumchlorides, which react with anilines to give 3‐phenylimino‐4‐chloro‐5‐alkylthio‐1, 2‐dithioles.
2‐Alkyliden‐1, 3‐dithia‐Heterocyclen aus 5‐Sulfonyl‐1, 2‐dithiol‐3‐onen und Alkoholaten
Authors: Bader JÖRg
Published: December 2004

Asymmetrically substituted 5‐sulfonyl‐1, 3‐dithiafulvenes (9a–g), all of which have the same configuration (called α), are obtained by reaction of 4‐chloro‐5‐sulfonyl‐1, 2‐dithiol‐3‐ones (3a–e) with sodium alkoxides. Side‐products formed are 4‐chloro‐5‐alkoxy‐1, 2‐dithiol‐3‐ones (5a and 5b), 3, 5‐bis‐alkylidene‐1, 2, 4‐trithiacyclopentanes (21 and 22), and (in some instances) minor amounts of compounds 33, 34, or 35. Reaction of 4‐phenyl‐5‐methylsulfonyl‐1, 2‐dithiol‐3‐one with sodium methoxide results in the formation of 4‐phenyl‐5‐methoxy‐1, 2‐dithiol‐3‐one (5c), the two cis‐trans‐isomers of 2, 4‐bis‐alkylidene‐1, 3‐dithiacyclobutane 24 and 25, and the 2, 5‐bis‐alkylidene‐1, 2, 4, 5‐tetrathiacyclohexane 26. Some conceivable reaction mechanisms are discussed, and proof is given for the structure of the major compounds. By treating 4‐chloro‐5‐(2′‐chloro‐ethylthio)‐1, 2‐dithiol‐3‐one with sodium methoxide, the 2‐alkylidene‐1, 3‐dithiolane 13 is obtained.

The sulfonyl groups of the 1, 3‐dithiafulvenes 9a–g described may be easily replaced by hydrogen or secondary amines, yielding compounds 14, 16 and 19, respectively.

When dissolved in strong acids and reprecipitated, asymmetrically substituted 2‐alkylidene‐1, 3‐dithia compounds may be converted into mixtures of all possible cis‐trans‐isomers thereof. Those isomers may be separated by fractional crystallization. Isomers 31 (called β) of 9 a‐‐g, and 32 of 16a, b, are obtained accordingly.
Propriétés thermodynamiques des mélanges binaires. Volume et énergie interne de formation des solutions de l'hexadécane dans les isomères de l'hexane
Authors: Fernández‐García J. G. , Guillemin M. , Boissonnas Ch. G.
Published: December 2004

The volumes of mixing of hexadecane and each of the isomers of hexane have been measured for the equimolar mixtures at 20°C. The results have been used together with previously measured values of ΔH to obtain ΔUv.

A very good correlation is found between the energy of mixing and the properties of the pure alkanes.
Applications synthétiques de la cyclisation d'alcools tertiaires γ‐éthyléniques en α‐bromotétrahydrofurannes sous l'action du N‐bromosuccinimide. I. Synthèse facile de la triméthyl‐2,2,5‐cycloheptène‐4‐one ou karahanaénone à partir du linalol
Authors: Demole Edouard , Enggist Paul
Published: December 2004

The ionic reaction of linalool and N‐bromosuccinimide in CCl4 at room temperature afforded 2‐methyl‐2‐vinyl‐5‐(1‐bromo‐1‐methyl‐ethyl)‐tetrahydrofuran (I). On treatment with refluxing collidine this compound yielded the intermediate allyl vinyl ether III, which immediatealy rearranged to 2,2, 5‐trimethylcyclohept‐4‐en‐one (V) or «karahanaenone» through a [3,3]‐sigmatropic process. Karahanaenone, a constituent of hop oil, was thus synthesized for the first time (overall yield 62% from linalool). The mechanisms of these reactions are discussed.
ESR.‐Untersuchung zur Reaktion von Hydroxylradikalen mit Glycin
Authors: Paul H. , Fischer H.
Published: December 2004

Radicals H2NĊHCOOH and H2NĊHCOO− which have different ESR. spectra are observed during the reaction of hydroxyl radicals with glycine in aqueous solution. Rapid and reversible exchange between the different dissociated radicals is induced by addition of phosphoric acid. The pH dependence of the ESR. spectra yields the pK value and rate constants for proton transfer reactions between the radicals and phosphoric acid.
Chiroptische Eigenschaften und absolute Konfiguration von 9, 9′‐Spirobifluoren‐Derivaten
Authors: Haas G. , Hulbert P. B. , Klyne W. , Prelog V. , Snatzke G.
Published: December 2004

The circular dichroism and optical rotatory dispersion of three vespirenes, three vespirones, and of some related 9, 9′‐spirobifluorene derivatives [4] have been measured. The absolute configurations of these compounds have been determined from chiroptical properties (CU., ORD.) in four ways which give mutually consistent results. For the (−)‐vespirenes the (R)‐configuration (Figs. 1 and 2) follows from 1 is treatment.
Equilibres conformationnels de dérivés de sucres à insaturation terminale
Authors: Tronchet J. M. J. , Baehler Br.
Published: December 2004

The conformation in solution of several unsatured sugars of the general type XHCCH—glycosyl has been studied by NMR. In the trans series, the population of the sterically permitted gauche conformer increases with the M‐ability of X. In the cis series, the population of the trans conformer increases with the space requirements of X. These phenomena are discussed.
The Rôle of Solvent Participation in Electrophilic Aromatic Substitution: Rates of a diazo coupling reaction in water and in aprotic polar solvents. 24th Communication on diazo coupling reactions
Authors: Penton J. R. , Zollinger H.
Published: December 2004

The rates of the diazo coupling reaction of 4‐toluenediazonium salts with N, N‐dimethylaniline in tetramethylene sulfone, acetonitrile, water, and nitromethane at 30°C are the same within a factor of 5. No significant influence of ‘gegenions’ (HSO or BF) was found. The results are explained by postulating little solvent reorganisation in the transition state. They are discussed comparatively with solvent effects in other electrophilic aromatic substitutions, particularly with regard to the reactions of nitronium salts.
C‐Glycosides, IV. Mise en évidence d'un mécanisme concurrent de la cyclo‐addition dipolaire‐1,3 concertée lors de la réaction d'une azométhine‐imine avec un dipolarophile acétylénique. Communication préliminaire
Authors: Tronchet J. M. J. , Perret Melle F.
Published: December 2004

The reaction of a glycosyl‐azomethine imine with an acetylenic dipolarophile in the usual conditions for 1, 3‐dipolar cycloaddition led to an α‐ethynyl‐hydrazone beside the ‘normal’ product of the reaction, i.e. the corresponding pyrazole. Deuteration experiments indicated that the two products are formed by two concurrent independent pathways. It is supposed that the slow step in the formation of the α‐acetylenic hydrazone is the ionization of the alcyne whose conjugated base reacts rapidly with the 1, 3‐dipole.
Projected electron density method of π‐eletron systems II. Excited states
Authors: Försterling H. D. , Kuhn H.
Published: December 2004

A perturbation theory based on the time‐dependent Schrödinger equation is presented; Coulombic interactions are taken into account and spin properties are neglected. Using wave functions given by the projected electron density method described in Part I as a basis set the energies of excited π‐electron states are calculated. For a series of porphyrin compounds the electronic spectra are calculated and are found to be in good agreement with experiment.
Wellenmechanische Absolutrechnung an einer intramolekularen Radikalreaktion an einem methyl– und hydroxylsubstituierten ungesättigten Kohlenwasserstoff
Authors: Janoschek R.
Published: December 2004

An energy surface for the intramolecular radical reaction oxygen radical ⇌ methylene radical has been estimated on an important part of the α‐Tocopherol molecule (Vitamin E), using the SCF–MO–LC(LCGO) method. The total energy of the oxygen radical is greater than that of the methylene radical by about 49.6 kcal/Mol. The height of the potential barrier between the two tautomeric radicals was calculated to be 54.6 kcal/Mol. The calculated life time of the oxygen radical was 5.3 sec.
Valence structures for N2O4. III
Authors: Harcourt R. D.
Published: December 2004

Further energies for types of N2O4 valence structures (or valence formulae) are reported. The results indicate that two sets of formulae might give satisfactory distributions of the mobile σ‐electrons. These are

Resonance between covalent and ionic formulae ((B) and (D) of Part II[8]);

A non‐paired spatial orbital formula ((F) of Part II [8]).

One estimate of the σ‐bond order for the NN bond is 0.4–0.5. For this, (i) is to be preferred, because it involves a much lower energy than (ii). But should the order be about 0.7, the energies of (i) and (ii) are similar, and both descriptions are satisfactory.

The ionic formula of (i) involves non‐localized bonding for the NO moiety. It may be replaced by a formula with localized bonds, and an almost identical energy.
A study of the ground state wave function of carbon monoxide
Authors: Siu Albert K. Q. , Davidson Ernest R.
Published: December 2004

A large configuration‐interaction calculation has been performed to determine the wave function, energy, and molecular properties of CO. The most important configurations were used to obtain the natural geminals and their occupation numbers. A pair‐energy approach to the correlation energy was attempted with results which differ significantly from the configuration‐interaction results.
Optimum hybrid orbitals in localized orbitals
Authors: Polák Rudolf
Published: December 2004

Using the criterion for maximizing the projection of localized bond orbitals onto the space spanned by the occupied MO's, a method for constructing hybrid orbitals of a molecule is described. For illustration purposes the method is applied to single‐determinant closed shell wave functions, calculated by means of ab initio and semiempirical procedures, for the molecules of methane, acetylene, ethylene, ethane, propylene, butadiene, ammonia and hydrogen cyanide. The predictions of hybridization are briefly discussed.
Molecular MC–SCF calculations
Authors: Levy B.
Published: December 2004

A practical method for finding multi‐configurational SCF wave functions is proposed. The basic equation is equivalent to the Brillouin theorem; comparison with the usual SCF equations obtained through effective hamiltonians gives an interpretation of the offdiagonal Lagrange multipliers. Numerical applications to Formaldehyde in a minimum Slater‐type orbital basis with four different variational wave functions are reported. The molecular orbitals found in these calculations are localized on the chemical bonds. The largest contributions to the energy are obtained from π‐π and dispersion‐type σ‐π correlation.
Self‐consistent spin‐polarized energy bands of sodium
Authors: Boring A. Michael
Published: December 2004

The energy bands of sodium have been calculated by the augmented‐plane wave method and carried to self‐consistency for both a non‐spin‐dependent and spin‐dependent potential. The results are compared with those of previous calculations and with experimental data. It was found that the energy gaps introduced by the spin‐dependent potential remained when the calculations were carried to self‐consistency. Analysis of the present results involved comparison of the spin‐dependent method with Löwdin's Alternant Molecular Orbital method and with Overhauser's Spin‐Density‐Wave model, and an analogy is drawn between the spin‐dependent calculation and spin‐polarized atomic calculations. By calculating the total energies as a functional of the self‐consistent charge desity, it was determined that the spin‐polarized crystal state had a lower energy than the state obtained from the non‐spin‐dependent potential. The approximations used in the calculations are discussed.
Gaussian overlap approximation in the projected Hartree–Fock method
Authors: Van Leuven P.
Published: December 2004

A method for the approximate calculation of matrix elements with respect to projected Hartree–Fock wave functions is proposed. The method is tested on some calculations in the many‐parameter AMO method. It is found that the approximation reduces the amount of work, involved in the evaluation of the energy, by a factor of five and that it reproduces the exact values to within a few per cent.
Determination of the non‐zero components of property tensors in environments of low symmetry
Authors: Boyle L. L.
Published: December 2004

A group‐theoretical method is presented whereby the number and identity of the non‐zero components of a property tensor in a (molecular or crystalline) environment of low symmetry may be determined.
Fifth‐rank molecular polarization tensors
Authors: Boyle L. L.
Published: December 2004

Fifth‐rank molecular polarization tensors are discussed in terms of their tensor group which includes both the spatial symmetry and the permutation symmetry of the suffixes. This latter may be described by certain four‐dimensional point groups, which in the nontotally symmetric cases may be projected into three‐dimensional space. The study leads to a determination of the number of independent components of these tensors and a discussion of the types of phenomena which they may be expected to produce.
Decoupling conditions for the vibronic equation in dimers
Authors: Witkowski Andrzej , Zgierski Marek
Published: December 2004

The analytical conditions are obtained and discussed under which the vibronic equations for dimers can be decoupled.
Extended group function calculations for H2O, NH3 and CH4
Authors: Franchini P. F. , Moccia R. , Zandomeneghi M.
Published: December 2004

Wave functions expressed as antisymmetrized products of strongly orthogonal geminals have been evaluated for H2O, NH3 and CH4. The geminals have been expressed as linear combinations of 2 × 2 detors constructed with localized SCF‐MO's. Several ground state observables have been computed together with the electric polarizabilities and magnetic susceptibilities. In addition, a configuration interaction calculation limited to all possible double group excitations has been carried out.
Comparison of two perturbation methods
Authors: Singh S. R. , Smith V. H.
Published: December 2004

Polikanov's perturbation method for the solution of the radial Schrödinger equation is shown to be equivalent to the usual Rayleigh‐Schrödinger method but with full normalization instead of intermediate noralization. The energy corrections are shown to be the same to all orders. The computational advantages of Polikanov's method are discussed. The method is illustrated by considering the two‐electron ions in the Hartree–Fock approximation.
Successive partitioning technique and Feenberg perturbation theory
Authors: Goscinski O. , Stepanov N.
Published: December 2004

Successive partitioning technique, when based on a modified bordering method for solving a system of linear equations and a relation for the inverse of a partitioned matrix leads to Feenberg's perturbation theory. This sheds light on the properties of the expansion, its bracketing properties and the nature of the “counting operators” used sometimes in this connection.
A study of some potential energy functions for diatomic molecules
Authors: Jain D. C.
Published: December 2004

A detailed study of the performance of the Morse, the Hulburt‐‐Hirschfelder and the Lippincott potential energy functions has been carried out by comparing them with the Rydberg–Klein–Rees potential energy curves for a number of electronic states of various diatomic molecules. Further, by employing the above potential energy functions, the radial Schrödinger equation has been solved for the vibrational energy levels, G(v), and the vibrational wave functions, ψv. The latter have been employed to determine the rotational constants, Bv, for the individual vibrational energy levels. Then the molecular constants, we, wexe, weye, Be, αe and γe for the various electronic states, have been computed by using the values of G(v) and Bv. A comparison of the molecular constants derived in this manner with the experimental ones reveals better agreement, in most cases, than that reported by previous workers.
Time‐dependent quantum theory II. Absorption of light by dimers: Quantum theory and classical analogy
Authors: Schurr J. M.
Published: December 2004

The quantum theory of light absorption by a pair of neighboring absorbers is developed in the point dipole approximation for the circumstance where excited states decay only by radiative damping. Comparison with classical local field theories, in which the monomers are represented by constant, frequency‐dependent complex polarizabilities, shows that these local field theories are valid for non‐harmonic absorbers only in the weak interaction limit, and only when there exist no states with both monomers simultaneously excited (e.g. one excited vibrationally, the other electronically) that are nearly degenerate with the single excitation states and also connected to them by appreciable transition moments. Failure of the local field theories is, thus, shown to be a consequence of the non‐harmonic nature of real absorbers.

Using a general relation between the level‐shift function and complex polarizability, a recipe is formulated for calculating the complex polarizability and spectrum of a dimer.
Padé approximants to physical properties via inner projections
Authors: Goscinski O. , Brändas E.
Published: December 2004

The [N, M] Padé approximants to functions formally associated to power series expanssions are expressed in terms of expectation values of inverse matrices. These formulae, which can be derived by the inner‐projection technique, lead to a simple analysis of the properties of serveral approximation methods and their inter‐relationships, in particular Gaussian integration, continued factorization and Padé approximations, which are of current interest in the calculation of physical properties. A relation with Fredholm integral equations and expansions of the resolvent is also discussed.

The use of operator inequalities in a systematic fashion is particularly convenient when both the function being approximated and the coefficients of the power series have physically meaningful expressions as moments of operators.
Analysis of reduced density matrices in the coordinate representation. II. The structure of closed‐shell atoms in the restricted Hartree–Fock approximation
Authors: Sperber Gunnar
Published: December 2004

The electron density and the Fermi hole of the ground states of the atoms He, Be, Ne, Mg, Ar, Ca, Zn, and Kr are studied in the restricted Hartree–Fock approximation. The use of single Slater‐type orbitals for the free atoms is also discussed.
On a formula of Braun and Rebane for variational bounds to overlap
Authors: Weinhold F. , Wang P. S. C.
Published: December 2004

A recent formula of Braun and Rebane for variational bounds to overlap is shown to be closely related to the methods of Rayner and of Weinhold for the same problem, and is extended to give upper and lower bounds to overlap in both ground and excited states.
Spin‐free quantum chemistry. XIX. Particle‐hole and pairing symmetries
Authors: Matsen F. A. , Welsher T. L. , Yurke B.
Published: December 2004

Particle–hole and pairing relationships are obtained within the framework of the unitary group formulation of the many‐electron problem using the concept of particle–hole conjugation. Besides the familiar relationships for alternant hydrocarbons, relationships among various pericyclic reaction paths are obtained.
Maximum and minimum overlap, localized, and hybrid orbitals for atoms and molecules by means of orthonormality‐constrained variation
Authors: Morikawa Tetsuo , I'haya Y. J.
Published: December 2004

It is shown that application of the orthonormality‐constrained variation method to the absolute squares of three kinds of overlap integrals leads to eigenvalue equations and of which the eigenvectors belonging to maximum (minimum) eigenvalues are the maximum (minimum) overlap, localized, and hybrid orbitals. In the eigenvalue equations, coupling operators similar to those used in SCF theory are found to occur. Connection of the maximum orbitals to a many‐shell model, a simple MO theory, and Löwdin's orthonormalization is also discussed.