bluuebunny/crossref_metadata_2025_split huggingface dataset:
Beiträge zur Chemie des Bors, XCVI: Die N‐Metallierung N‐substituierter Aminodimethylborane mit Organolithium‐Verbindungen
Authors: Fußstetter Hermann , Nöth Heinrich 
Published: June 2007

AbstractIn der Reihe (CH3)2BNHN(CH3)2(1), BNHSi(CH3)2BNHB(CH3)2 (7) gewinnt die Lewis‐Acidität der (CH3)2BN‐Gruppe im Vergleich zur Protonenacidität der NH‐Gruppe gegenüber Lithiumorganylen zunehmend an Gewicht. N‐Lithioderivate (2, 5) sind nur mehr von 1 und 4 darstellbar. NMR‐spektroskopisch ist bei allen Reaktionen mit LiCH3 die Boratstufe [(CH3)3BNHR]Li (3, 6, 8) nachweisbar, die bei 3 und 6 unter Methanabspaltung, bei 8 hingegen zu LiB(CH3)4 und (CH3BNH)3 zerfällt. Die NMR‐Spektren der N‐Lithioaminoborane 2 und 5 belegen eine Bindungsordnung > 1 für die BN‐Bindung. Nach Massenspektren dürfte 5 hexamer und 2 polymer aufgebaut sein.
Konfiguration und cis‐Effekt bei Diphenyl‐(oxa)bicyclo[4.2.0]octanen
Authors: Kaupp Gerd , Stark Michael , Fritz Hans 
Published: June 2007

AbstractDie Photoadditionen von trans‐Stilben an elektronenreiche Alkene (z. B. 2b, 4d u.a.) werden im Hinblick auf mit dem üblichen Zweistufenmechanismus nicht vereinbare Literaturangaben bei 4d untersucht. Im Gegensatz zu Literaturangaben sind die Photoaddukte cis‐verknüpft und besitzen trans‐ständige Phenylgruppen. Die Photolyse der verschiedenen Stilbenaddukte folgt dem bei zweistufigen Vierringspaltungen gültigen cis‐Effekt. Die beträchtlichen Selektivitätsvariationen werden diskutiert. Hinweise auf die Strukturen und Gleichgewichte von Konformeren werden aus Molekülmodellen, der Feinstruktur von UV‐Spektren und Fluoreszenzdaten gewonnen. Neben den Vierringspaltungen werden in den meisten Fällen schon bei −190°C geometrische Isomerisierungen beobachtet. Einige bifunktionelle Styrylenolether‐Derivate werden isoliert und z. T. der intramolekularen [2 + 2]‐Photocycloaddition unterworfen. Als Sonderfall wird bei der Belichtung von 14 eine neue [4 + 2 + 2]‐Photocycloreversion beobachtet.
Übergangsmetall‐Carbin‐Komplexe, XLIII: Reduktion einer Metall‐Kohlenstoff‐Dreifachbindung
Authors: Fischer Ernst Otto , Frank Albin 
Published: June 2007

Transition Metal Carbyne Complexes, XLIII: Reduction of a Metal‐Carbon Triple BondReaction of [π‐C5H5(CO)2ReCC6H5]+[BCl4]− with Et2AlH yields — depending on reaction conditions — the novel secondary carbene complex π‐C5H5(CO)2ReCHC6H5 (2) or the σ‐benzylhydrido complex π‐C5H5(CO)2HReCH2C6H5 (3). The reaction is the first example of a stepwise reduction of a metal‐carbon triple bond to a single bond.
Darstellung von Vinylisothiocyanaten durch Schwefel‐Eliminierung aus Δ3‐1,3‐Thiazolin‐2‐thionen
Authors: Hussein Ahmad Q. , Abu‐Taha Ahmed , Jochims Johannes C. 
Published: June 2007

Syntheses of Vinyl Isothiocyanates by Sulfur Elimination from Δ3‐1,3‐Thiazoline‐2‐thionesThe Δ3‐thiazoline‐2‐thiones 1a, b eliminate sulfur thermally, photolytically, or with trimethyl phosphite to give the vinyl isothiocyanates 2a, b. Compound 2a forms a thiosemicarbazone 3a which cyclizes thermally to 4. This easily splits off the isopropyl group to give the triazolinethione 5. The vinyl isothiocyanate 2b rearranges thermally or photochemically to the isoquinoline‐1‐thione 7 which itself is photolabile.
Bildung, Struktur und Reaktivität von (Pentafluorphenyl)bor‐tert‐butylimid und seinem Cyclodimeren
Authors: Paetzold Peter , Richter Anette , Thijssen Theo , Würtenberg Stefan 
Published: June 2007

AbstractBei der Gasphasenthermolyse der Aminoborane RB(Cl)‐N(SiMe3)R' (la–j) bei 500–600°C erhält man neben Me3SiCl entweder die Borazine (RBNR')3 (3a–f) oder die Diazadiboretidine (RBNR')2 (2g–h) oder das Borimid C6F5–B = N–tBu (4i) oder ‐ im Falle R' = Mesityl – das bicyclische Produkt eines intramolekularen Ringschlusses 5. 4i dimerisiert bei Raumtemperatur ohne Lösungsmittel schnell, in Lösung weniger rasch zu seinem Cyclodimeren 2i. Dieses kristallisiert in der Raumgruppe C2/c. 2i erfährt mit Ketonen im Verhältnis 1:1 eine enolytische Ring‐öffnung (6i,6í). Die CO‐Bindung ungesättigter Aldehyde schiebt sich in den Vierring von 2i unter Sechsringbildung (7i, 7í) ein. Mit PhHC = N(O)Me setzt sich 2i unter Abspaltung von PhHC = NtBu zum Oxadiazadiborolidin 9i um. IR‐ und NMR‐spektroskopische Befunde sprechen sowohl für eine BN‐Bindungsordnung größer als zwei als auch für BC‐π‐Wechselwirkungen in der Titelverbindung 4i. Mit Ph2C = O reagiert 4i analog zur Wittig‐Reaktion zu (C6F5BO)3 und Ph2C = NtBu und dieses geht mit 4i quantitativ eine [2 + 2]‐Cycloaddition zu 10i ein. Mit Cyclopentadien setzt sich 4i als Dienophil im Sinne einer Diels‐Alder‐Reaktion zu 11i um.
Bausteine von Oligosacchariden, XVIII. Synthese von 4‐O‐Aminosäure‐ und 4‐O‐Carbamidsäureestern von Garamin
Authors: Paulsen Hans , Böttcher Henning 
Published: June 2007

Abstract2′,4′,5‐Tri‐O‐benzyl‐l,2″,3,3′,6″‐pentakis‐N‐(benzyloxycarbonyl)gentamicin C (7) läßt sich selektiv mit Trifluoressigsäure 2′,4′,5‐Tri‐O‐benzyl‐1,3,3′‐tris‐(N‐benzyloxycarbonyl)garamin (13)spalten. Die unsubstituierte 4‐OH‐Gruppe von 13 wird in die Ester 16–19 und über das Imidazol‐Derivat 20 in die Carbamidsäureester 21–26 übergeführt. Hydrogenolytische Entblockierung liefert in einem Schritt die freien 4‐O‐Aminosäure‐ und 4‐O‐Carbamidsäureester des Garamins 29–31 und 32–38.
Notizen. Synthese und Eigenschaften von Lithium‐tetrakis(trimethylsilyl)aluminat‐Komplexen
Authors: Rösch Lutz , Altnau Gerald 
Published: June 2007

Synthesis and Properties of Lithium Tetrakis(trimethylsilyl)aluminate ComplexesChlorotrimethylsilane reacts with aluminium and lithium in ether in the presence of mercury to form lithium tetrakis(trimethylsilyl)aluminate, coordinated with diethyl ether, tetrahydrofurane, or dimethoxyethane. Unsolvated lithium tetrakis(trimethylsilyl)aluminate results by repeated sublimation of the ether adduct. The IR, Raman, and NMR spectra are discussed.
Analyse des Makro‐ und Mikromischens mit Hilfe von laserdiagnostischen Verfahren
Authors: Faes M. , Glasmacher B. 
Published: June 2007

AbstractIn vielen Bereichen der chemischen, pharmazeutischen und Lebensmittelindustrie zählen Mischprozesse zu den am häufigsten eingesetzten Verfahren. Trotz ihrer häufigen Anwendung ist es bisher jedoch noch nicht gelungen, die Zusammenhänge zwischen dem konvektiven Transport im Strömungsfeld, dem diffusiven Transport un d der Kinetik einer chemischen Reaktion vorauszusagen. Dazu sind experimentelle Untersuchungen durchzuführen, die eine Betrachtung der Transportmechanismen in einem Mischprozess auf unterschiedlichen Skalen erlauben. Für die Untersuchungen der ablaufenden Transportphänomene auf der Makro‐ und Mikroskala werden zwei laseroptische Verfahren eingesetzt, die eine Kopplung der zu betrachtenden Prozesse gewährleisten.
Beanspruchung von Partikeln und Fluidelementen beim Rühren
Authors: Wollny St. , Sperling R. , Kraume M. , Ritter J. 
Published: June 2007

AbstractIn Fermentationsanlagen können tierische Zellen durch mechanische Beanspruchungen irreversibel geschädigt werden, wodurch die Produktivität sowie die Produktreinheit sinken. Da solche Fermentationsprozesse häufig in Rührreaktoren bewerkstelligt werden, sind numerische und experimentelle Untersuchungen zur Klärung der physikalischen Effekte für die Prozessgestaltung/‐optimierung von Nutzen.
Aktuelle Entwicklungen in der CFD für gerührte Systeme
Authors: Paschedag A. R. , Kassera V. , Sperling R. 
Published: June 2007

AbstractComputational Fluid Dynamics (CFD) ergänzt auch in der Verfahrenstechnik und speziell in der Rührtechnik zunehmend experimentelle Untersuchungen und klassische Auslegungsregeln beim gezielten Design und der Optimierung von Apparaten. Die Vorzüge liegen einerseits in der Bereitstellung ortsaufgelöster Informationen, die benötigt werden, um z. B. lokale Überhitzungen oder kritische Scherbeanspruchungen zu vermeiden, die messtechnisch nicht oder nur mit großem Aufwand zugänglich sind. Andererseits können Parameterstudien mit CFD oft preiswerter durchgeführt werden als experimentelle Untersuchungen. Der Beitrag dokumentiert Entwicklungen der letzten Jahre, die den Einsatz der CFD auch für industrielle rührtechnische Anwendungen sinnvoll gemacht haben. Schwerpunkte liegen auf der Modellierung der bewegten Einbauten, der Turbulenzmodellierung, der Behandlung nicht‐Newtonscher Fluide und der Simulation von Mehrphasenströmungen.
Verification of a front‐tracking model of two‐fluid interface Kelvin–Helmholtz instability by study of travelling waves
Authors: Tong Mingming , Browne David J. 
Published: June 2007

AbstractA novel travelling wave case study is developed to verify a front‐tracking model of Kelvin–Helmholtz (K–H) instability of immiscible, incompressible two‐fluid flow. In this benchmark comparison, two fluids flow at different velocities in the same parallel horizontal direction, forming travelling waves when the interface between the fluids is set to oscillate in the vertical direction at the inlet. With a specific oscillation frequency, the effect of the inlet velocity difference, or gap, on the interface undulation spatial propagation, such as wave damping or wave amplification is quantitatively analysed. By using a variety of different inlet velocity gaps and oscillation frequencies, the effects of the gap on wave propagation are investigated over a large range of wave numbers. The simulation predictions are compared with the result of the linear stability theory. This comparison represents a comprehensive verification of the current front‐tracking model of K–H instability. Copyright © 2007 John Wiley & Sons, Ltd.
Exhibiting artwork: Consider the illuminating source
Authors: Berns Roy S. , Grum Franc 
Published: June 2007

AbstractThis article describes the steps that should be considered for the proper illumination of artwork. In particular, our intent is to show how a different illuminating environment from one intended by the artist affects the color appearance of exhibited paintings. Using five different illuminants and several illumination levels, it is shown for eight artists' pigments that large color‐appearance differences occur. This is true even after the effects of chromatic adaptation are taken into account.
Color space of the coloroid color system
Authors: Nemcsics Antal 
Published: June 2007

AbstractThe Coloroid color system is a Hungarian standard color order system. This article describes the color space of the Coloroid system and its relationship to the CIE colorimetric space and the spaces associated with the Munsell and DIN color order systems. The Coloroid system is presented as a compromise of principles of uniformity in regard to color difference and color harmony, as well as ease of mapping into the CIE colorimetric space.
The color specification of scottish tartans
Authors: Sinclair Roy S. 
Published: June 2007

AbstractThe methods used by the Scottish Museum of Tartans for recording the yarn count and color specifications of tartans are described. The origin of the colors used in old tartans has been investigated by preparing dyeings on wool using extracts from a large number of plants native to Scotland. The colors so obtained have been recorded, and a selection of the results is presented in terms of CIELAB coordinates and compared with the colors obtained from the well‐known natural dyes of the past. The changes in color caused by fading have also been recorded and the results analyzed to clarify the origin of the colors used in the modern, ancient, and reproduction tartans manufactured today.
Color vision theories in nineteenth century germany between idealism and empiricism
Authors: Lang Heinwig 
Published: June 2007

AbstractHelmholtz and Hering are well known names in the history of physiological optics and color‐vision theory, whereas Goethe's work on color is generally regarded as standing outside the mainstream of scientific tradition. This article shows that Goethe not only stimulated the philosopher Schopenhauer to publish on color vision, but also Purkyňe and Johannes Müller, then the most influential authorities writing on sensory physiology in Germany. The latter was Helmholtz's teacher. The treatment of subjective color‐contrast phenomena by different German nineteenth‐century authors reflects the conflict between idealism and empiricism. In Germany idealism had an overwhelming influence on scientific ideas and institutions at the beginning of the last century. After 1830 this influence declined rapidly and was replaced by empiricism. But some of the idealistic stimulations remained active until the end of the century, especially in the work of Fechner and Hering.
The influence of spectral bandpass on accuracy of tristimulus data
Authors: Stearns E. I. 
Published: June 2007

AbstractWhen calculating tristimulus values from spectral radiance factors which were measured with a spectral bandpass of 10 nm, using data from the same specimen measured with a spectral bandpass of 1 nm and calculated with a 1‐nm interval as standard, and evaluating the significance of the difference in tristimulus values with the CIELAB color difference formula, it is highly probable that a 1‐nm calculation interval will give no greater accuracy than a 10‐nm calculation interval. For this reason it is recommended that the CIE reconsider their approval of the deletion of the 10‐nm calculation interval from the new edition of Publication CIE 15.
A Painter's thoughts on color and form
Authors: Osborne Roy 
Published: June 2007

AbstractLike that of many art students, my initial training seemed dominated by linear drawing, so that painting too often became a matter of outlining shapes and then coloring them in. It was not until I more closely studied the work of Cézanne. Seurat, Robert Delaunay, and other great colorists, that I gained more insight into how color might be used independently of drawing, of how color could create its own form and ultimately become a subject of artistic experiment in its own right. This article examines one artist's thoughts on the relationship between drawing and color, set within a wider, art‐historical context.
Modeling the mixing behavior of inks with polynomials
Authors: Vachon Guy 
Published: June 2007

AbstractA technique for developing equations to predict the color of an ink combination is described. A complete characterization of a printing process inherently requires a great deal of data. It is possible to fit higher‐order polynomials to ink data. Pobboravsky fit ink data by optimizing polynomials through linear regressions with limited success. The techniques described depict and overcome the limitations of previous attempts at modeling the ink mixing behavior with polynomials.
Colour‐distance judgement and the influence of the background in colour reproduction
Authors: Schultz Ursula 
Published: June 2007

AbstractThe influence of the background in colour reproduction can be described in colorimetric terms by the use of corrections to the colorimetric scaling factors. This leads to transformation formulae that describe the change of chromatic adaptation, and also to an extended definition of the so‐called “colour of the state of chromatic adaptation.” The method leads to an improved reconciliation between the specification of colour‐rendering properties in both colour photography and multicolour printing and the visual evaluation. Certain problems in colorimetry may also become more easily understandable by the incorporation of such peripheral influences. Whereas the physiologically related scaling‐factor corrections are of first‐order importance, it is shown that stray‐light effects, which are physical contributing factors, are only of the second order.
Spectral tuning of opponent channels is spatially dependent
Authors: Finkelstein Marcia A. 
Published: June 2007

AbstractPsychophysical detection and appearance data suggest that the spectral tuning of opponent pathways varies with test size. The present study examines the effect on spectral sensitivity of the relative size of test and surround fields. Increment thresholds and flashed‐field sensitivities were obtained for 580 nm and 641 nm targets. Three spatial configurations were used. The pattern of sensitivity loss is shown to depend on the spatial relation between test and field; the effect of the spatial relation in turn depends on test wavelength. The findings are explained by the activity of a changing network of spatially and spectrally opponent cells.
Recursive quadratic programming algorithm for color matching
Authors: Cogno J. A. 
Published: June 2007

AbstractA recursive quadratic programming (RQP) algorithm for color matching is described. RQP does not work on the assumption that the difference of spectral reflectance between sample and match can be approximated by a first‐order expansion. Color matching is instead obtained only by agreement of a trichromatic specification. A numerical example showing a possible field of application of RQP is presented.
From softcopy to hardcopy on a desert island
Authors: Brill Michael H. , Panken Neal 
Published: June 2007

AbstractA computer program is written that converts from a digital color image (driving the phosphors of a softcopy video display) to the areal dye densities for a halftone hardcopy device. The program is intended to be generic enough for acceptable color reproduction between a variety of devices without slavish attention to such factors as the phosphor and dye spectra. Only one parameter called “subtractiveness” is empirically adjustable depending on how much image darkening must be compensated. No particular theory is invoked, but the transformation between RGB inputs and CMY outputs is constrained to ensure (1) symmetry among the image planes; (2) no higher than third‐degree polynomials; and (3) nominal correspondence of the eight extremal colors red, green, blue, cyan, magenta, yellow, white, and black. When tested on one set of devices, the program works well enough for the “desert islands” inhabited by most users.
Scaling procedures for specifying color appearance
Authors: Gordon James , Abramov Israel 
Published: June 2007

AbstractColors of objects are often specified by color matches in some standard colorimetric system. While color‐matching allows a color to be reproduced accurately, it does not specify what the color actually looks like. Color appearance (i.e., hue, saturation, brightness) can be measured by direct psychophysical scaling techniques; however, these methods have not been standardized and have been confined mostly to the laboratory. We have examined several variants of continuous, numerical scaling of hue and saturation to find a procedure that is usable, even by untrained observers. Appearances of monochromatic, equal‐luminance light flashes were scaled along the dimensions of the unique hue sensations (red, yellow, green, blue) and apparent saturation. These functions were obtained for various stimulus conditions, including changes in stimulus luminance, size, and eccentricity. Multidimensional scaling methods were used to derive metrically uniform color appearance diagrams from the hue and saturation scaling data. Validity of the scaling procedures was assessed by deriving well‐known visual functions, such as wavelength discrimination, from the color appearance diagrams. The direct scaling method was shown to be generally useful, and both trained and untrained observers readily and reliably used the technique.
Large colour differences measured by spontaneous gestalt formation
Authors: Stalmeier Peep F. M. , De Weert Charles M. M. 
Published: June 2007

AbstractGestalt formation is used as a means to measure large colour differences. The stimulus is presented in the form of the Star of David, being made of two overlapping triangles of different colour, with the overlap being in a third colour. Through Gestalt formation the subjects perceive a triangle pointing to the left or to the right. Gestalt formation is assumed to occur for colour combinations with the smallest perceptual distance. We simulated responses at the ordinal level with several uniform‐colour‐distance models, derived from near‐threshold colour‐discrimination experiments. For isoluminant colours 84% of the responses, and for nonisoluminant colours 76% of the responses, are predicted correctly by the best model. We argue that the tritanopic direction is crucial for the understanding of large‐colour‐difference data.
Background stimulus for invariant spectral sensitivity
Authors: Fuld Kenneth , Sparrow John E. , Daning Robin , Slade Carolyn W. 
Published: June 2007

AbstractIncrement‐threshold spectral sensitivity was determined with backgrounds of four different chromaticities and two different troland (td) levels. One background was equivalent to a field delivering to the receptors an equal quantal flux at all visible wavelengths. Another background approximated CIE Illuminant A. Light from a chromatically unfiltered xenon‐arc lamp provided a third background. The fourth background was monochromatic at 470 nm. Backgrounds were presented at 10 and 1000 td. Foveal spectral sensitivity determined on each of these backgrounds was compared to that measured for the dark‐adapted state. The 10‐ and 1000‐td equal‐quantal fields yielded the functions that most closely approximated the curve resulting from the dark‐adapted condition, suggesting that such an equal‐quantal field, which appeared as a saturated blue, is neutral for measurements of spectral sensitivity. Because of the putative contribution of the opponent chromatic channels to spectral sensitivity determined using increment thresholds, the results further suggest that at the detection stage of these channels an equal‐quantal field provides a balanced state of adaptation.
Color coding for rapid location of small symbols
Authors: Carter Robert C. , Carter Ellen C. 
Published: June 2007

AbstractColor coding for small symbols is discussed. An exploratory study of visual search on an electronic display is described. Colors of small symbols (subtending less than 30′) are less distinct than those of 1° and 2° symbols. The study shows that surround luminance is a factor having its own effect that also alters the effect of symbol size on color perception. Human performance using small symbols is better when target symbols have a larger color difference (CIELUV) from both distractor symbols and the surround. The effect of reduced symbol size is accentuated by differences between surround luminance and symbol luminances. To predict human performance in tasks requiring rapid location of small symbols, one should consider surround and symbol luminances as well as color differences.
Empirical modeling of systematic spectrophotometric errors
Authors: Berns Roy S. , Petersen Kelvin H. 
Published: June 2007

AbstractSpectrophotometers, as electro‐mechanical‐optical devices, perform at a finite level of accuracy. This accuracy is limited by such factors as monochromator design, detector linearity, and cost. Generally, both the diagnosis and correction of spectrophotometric errors require a number of calibrated standard reference materials and considerable effort and commitment on the part of the user. A technique using multiple linear regression has been developed, based on the measurement of several suitably chosen standard reference materials, to both diagnose and correct systematic spectrophotometric errors, including photometric zero errors photometric linear and nonlinear scale errors, wavelength linear and nonlinear scale errors, and bandwidth errors. The use of a single chromatic ceramic tile to correct systematic errors improved the colorimetric accuracy of a set of chromatic and neutral tiles by a factor of two for a typical industrial‐oriented spectrophotometer. Greater improvement can be achieved by increasing the number of tiles and performing a separate regression at each measured wavelength., These techniques have been extremely useful in improving inter‐instrument agreement for instruments with similar geometry.