bluuebunny/crossref_metadata_2025 huggingface dataset:
GPRS system enhancement by employing LDPC codes
Authors: Keyrouz Fakheredine , Xu Wen
Published: May 2007

We address the application and design of low‐density parity‐check (LDPC) codes to enhance the General Packet Radio Service (GPRS) system in order to support services such as the Multimedia Broadcast Multicast Service (MBMS). Advances in coding theory and further reduction in integrated circuit size have promoted LDPC codes to become one of the most attractive forward error correction (FEC) technologies in practice. The GPRS as well as enhanced GPRS (EGPRS) system currently uses the well‐known convolutional code (CC) as an FEC mechanism, and the Viterbi algorithm for decoding. With the recent introduction of MBMS, new applications that require more bandwidth and reliability are foreseen. It is known that the current (E)GPRS system does not perform well enough without further modifications, therefore, more efficient information distribution schemes need to be considered. To meet these increased requirements, especially for MBMS, we study the introduction of carefully designed LDPC codes at the physical layer. To exploit the full benefit of the superior performance of LDPC codes for large data block lengths, a modification in the GPRS protocol stack is proposed where larger RLC/MAC blocks are allowed, and its impact on the existing GPRS protocol stack is minimised. Copyright © 2007 John Wiley & Sons, Ltd.
Discordant lymphatic drainage patterns revealed by serial lymphoscintigraphy in cutaneous head and neck malignancies
Authors: Willis Alliric I. , Ridge John A.
Published: May 2007

Background.

We analyzed the variability and accuracy of sentinel lymph node (SLN) identification by lymphoscintigraphy performed preoperatively and repeated on the day of operation in patients with melanoma or Merkel cell cancer.

Methods.

Twenty‐five prospectively studied patients had lymphoscintigraphy prior to and on the day of operation. Discordance between lymphoscintograms was defined as change in location of SLN or failure to identify a SLN by one of the studies.

Results.

In 22 of 24 assessable cases (92%), SLNs were excised. Preoperative lymphoscintigraphy was correct in 19 of 22 (86%) cases. Day of operation lymphoscintigraphy was correct in 20 of 22 (91%) cases. SLN location was as classically described in 24 of 25 (96%) cases. Discordance between lymphoscintigraphy studies was 32% (8/25 patients). Half with discordant migration (8%) yielded metastases in basins not identified by day of operation lymphoscintigraphy but demonstrated by preoperative lymphoscintigraphy.

Conclusions.

Head and neck lymphatic drainage patterns not only vary between patients but also can vary with time for a single patient. © 2007 Wiley Periodicals, Inc. Head Neck 2007
First and second line imatinib treatment in chronic myelogenous leukemia patients expressing rare e1a2 or e19a2 BCR–ABL transcripts
Authors: Andrikovics Hajnalka , Nahajevszky Sarolta , Szilvási Anikó , Bors András , Ádám Emma , Kozma András , Kajtár Béla , Barta Anikó , Poros Anna , Tordai Attila
Published: May 2007

During the formation of the Philadelphia (Ph) chromosome, in the majority of chronic myelogenous leukemia (CML) patients, the chromosome 22 breakpoint is located in the major breakpoint cluster region of the BCR gene (M‐bcr). Minor and micro breakpoint cluster regions (m‐bcr with e1a2 transcript and µ‐bcr with e19a2 transcript) are rarely affected and have been suggested to be associated with peculiar CML phenotypes. Despite the different clinical characteristics, it is currently not established, whether different therapeutic options are preferably recommended for the treatment of e1a2 or e19a2 CML. Here we report two patients with e1a2 and one patient with e19a2 translocations, treated with different approaches including imatinib. First and second line imatinib treatments induced haematologic response in all of the three patients, and major cytogenetic response in one patient with e1a2, as well as in the patient with e19a2 CML. However, relapse occurred in the patient with e19a2 CML, possibly caused by the presence of additional chromosomal abnormalities such as an extra Ph chromosome, and loss of chromosome Y. Stem cell transplantation (SCT) therapy caused complete haematologic response with molecular remission; however, the patient died of infectious complication. We conclude that in patients with rare BCR–ABL variants, the effectiveness of imatininb treatment may be influenced by the CML stage besides the actual molecular type of the rare transcript. However, this conclusion cannot be generalized to larger patient groups with rare BCR–ABL variants for which further studies may be needed. Copyright © 2007 John Wiley & Sons, Ltd.
Reduced basis approximation and a posteriori error estimation for stress intensity factors
Authors: Huynh D. B. P. , Patera A. T.
Published: May 2007

We develop reduced basis approximations, rigorous a posteriori error bounds, and offline–online computational procedures for the accurate, fast, and reliable prediction of stress intensity factors or strain energy release rates for ‘Mode I’ linear elastic crack problems relevant to fracture mechanics. We demonstrate the efficiency and rigor of our numerical method in several examples. Copyright © 2007 John Wiley & Sons, Ltd.
Gas solubility and permeability in MFA
Authors: Fossati P. , Sanguineti A. , De Angelis M. G. , Baschetti M. G. , Doghieri F. , Sarti G. C.
Published: May 2007

An experimental analysis has been performed in this work, aimed to the characterization of thermodynamic and mass transport properties of a semicrystalline fluoro polymer (MFA) obtained from the copolymerization of tetrafluoroethylene (TFE) and perfluoromethylvinylether. Sorption and permeation experiments for two alkanes and corresponding perfluorinated compounds in MFA were performed at two different temperatures and solubility coefficients, as well as diffusivity and permeability, were determined. Experimental data were analyzed through different thermodynamic models to draw general conclusions about properties of MFA polymeric phases. Special attention was devoted to the glassy nature of MFA polymeric mixtures around room temperature. Indeed, analysis of experimental sorption data was performed through the use of specific models for glassy polymeric phases as well as by means of classical equilibrium models for fluid mixtures. Conclusions have been drawn from the aforementioned analysis, which significantly contributes to the discussion of correct location of glass‐transition temperature for PTFE and its copolymers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1637–1652, 2007
Advantages of thin single‐photon avalanche diodes
Authors: Tan S. L. , Ong D. S. , Yow H. K.
Published: May 2007

The breakdown characteristics and timing jitter of thin and thick GaAs single‐photon avalanche diodes are analyzed using a random ionization path length model. The larger relative dead space in thin devices is found to increase the sharpness of breakdown probability curves. Thin devices also produce lower timing jitter as a result of larger feedback ionization at high fields and weak dependence of jitter on dead space. Thus, if the dark count rate associated with higher electric field can be compensated, then thin devices may offer better performance in terms of faster breakdown and lower timing jitter, in addition to the known benefits of shorter detector dead time and velocity overshoot effects. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Amorphous BeN as a new solid host for rare‐earth‐related luminescent materials
Authors: Zanatta A. R. , Richardson H. H. , Kordesch M. E.
Published: May 2007

Beryllium‐nitride (BeN) thin films were prepared by sputtering a Be target in an atmosphere of pure nitrogen. The films were doped with samarium simply by placing a piece of Sm metal on the surface of the Be target. Under these deposition conditions the films present an amorphous structure and an optical bandgap of approx. 4 eV. They also exhibit visible light emission due to Sm3+ ions as a result of either photon or electron excitation. The present experimental results show that amorphous BeN films are suitable, and efficient, III‐nitride hosts for rare‐earth doping purposes. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An Osculatory Extension of Cauchy's Rational Interpolation Formula
Authors: Salzer H. E.
Published: May 2007

An explicit formula for osculatory rational interpolation, in terms of functional values at every node, and any number of consecutive derivatives at one node, is derived from Cauchy's rational interpolation formula by solving the equivalent problem of finding the corresponding confluent limits of a non‐linear generalization of divided differences.
Stabilitätsuntersuchungen mit Hilfe der kontinuierlichen Thermodynamik
Authors: Bergmann J. , Kehlen H. , Rätzsch M. T.
Published: May 2007

Die kontinuierliche Thermodynamik [1–5] stellt eine Version der Thermodynamik dar, bei der die Zusammensetzung durch eine kontinuierliche Verteilungsfunktion statt durch die Molenbrüche individueller Komponenten beschrieben wird. Dadurch ermöglicht sie eine einfache Behandlung komplexer Vielstoffgemische, in denen eine große Zahl sehr ähnlicher Molekülarten auftritt (Erdöl, Polymere). Die übliche Form der thermodynamischen Stabilitätstheorie mit den bekannten Determinantenkriterien ist im Rahmen der kontinuierlichen Thermodynamik nicht anwendbar. In der vorliegenden Arbeit wird die Stabilitätstheorie auf eine Form gebracht, die der Beschreibung der Zusammensetzung durch Verteilungsfunktionen angepaßt ist.
Onset of Chaos and Global Analytical Solutions for Duffing's Oscillator
Authors: Schmidt G.
Published: May 2007

For the example of Duffing's oscillator, the discrepancy between the onset of chaotic motions found numerically and the results of analytical approximation is investigated by an analytical‐numerical method of trigonometric iteration. A fanning of the approximate response curves is found which corresponds to the non‐convergence of the approximations and the onset of chaotic motions.
General Concept of the Analysis of Thin Elastic Shells
Authors: Stumpf H.
Published: May 2007

Under the assumption of small strains the Lagrangian equations of the unrestricted rotation shell theory can be derived by applying the stationarity principle of total potential energy. It is shown that for a non‐rational change of the curvature tensor the equilibrium equations, the static boundary conditions and also the geometric boundary conditions are non‐rational partial differential equations. A nonlinear operator description is introduced allowing to formulate in a compact form the unrestricted rotation shell theory as well as the energy‐consistent simplified theories including the linear shell theory and various types of moderate and large rotation shell theories. The equations of an incremental deformation analysis, the stability and the postbuckling equations are derived and it is shown that they can be represented as functions of the Gâteaux differentials of the introduced shell operators. As an example of a highly nonlinear shell structure a torus under ring‐load is calculated numerically by applying the shallow shell theory, a moderate and a large rotation shell theory.
The Bending of Plates and Their Stability Region
Authors: Beckert H.
Published: May 2007

In the first part of the paper we determine the static stability and instability regions of a plate in the Banach space C1(σik) of the stress components. In the second part the initial value problem of the general dynamic equations in plate theory is solved for describing the bending of plates under heavy blows.
Ein vierdimensionales Abbildungsprinzip für ebene Bewegungen
Authors: Wunderlich W.
Published: May 2007

Die Punktbahnen eines ebenen Zwanglaufs π'/π werden gedeutet als verschiedene Parallelprojektionen einer gewissen Bild kurve k in einem vierdimensionalen euklidischen Raum R4, der die Rastebene π enthält. Die Projektionsachsen bilden ein elliptisches Strahlnetz im Fernraum des R4 und sind den einzelnen Punkten der Gangebene π' zugeordnet, während die Punkte von k den einzelnen Lagen von π' entsprechen. Das Abbildungsprinzip erweist sich insbesonders für algebraische Zwangläufe als nützlich und wird durch Beispiele illustriert. Auch die beiden Polkurven der Bewegung sind vom R4 aus deutbar.
Laminated Orthotropic Plates under Subdifferential Boundary Conditions. A Variational‐Hemivariational Inequality Approach
Authors: Stavroulakis G. E. , Panagiotopoulos P. D.
Published: May 2007

This paper deals with an orthotropic laminated plate concerning the delamination problem. A nonmonotone multivalued law simulates the mechanical behaviour of the binding material. This law is written in terms of a generalized gradient (in the sense of F. H. Clarke) of an appropriately defined nonconvex superpotential. Moreover, monotone, e.g. frictional slipallowing boundary conditions of subdifferential type are assumed to hold, which are obtained from a convex superpotential through subdifferentiation. The problem is formulated as a variational‐hemivariational inequality which physically expresses the principle of virtual work in inequality form. The existence and the approximation of the solution of this inequality is discussed by an appropriate combination of compactness, monotonicity and average value arguments.
Three Routes to Chaos in Simple Sinusoidally Driven Oscillators
Authors: Awrejcewicz Jan
Published: May 2007

Es werden drei verschiedene Szenarien für sehr einfache nichtlineare Schwinger unter sinoidaler Anregung aufgezeigt, die von periodischer zu chaotischer Bewegung führen. Die numerische Vorgehensweise basiert auf dem Schieß‐Verfahren. Periodische Orbits werden bei Parameteränderung anhand der Charakteristischen Multiplikatoren verfolgt. Es werden Übergänge diskutiert, bei denen einer der Multiplikatoren den Einheitskreis bei + 1 oder —1 (Periodenverdopplung) kreuzt. Das dritte Beispiel zeigt Chaos, nachdem ein Multiplikatoren‐Paar gleichzeitig den Einheitskreis überquert.
The Convergence of Discretization Methods if Applied to Weakly Formulated Problems. Theory and Examples
Authors: Ansorge R , Lei J
Published: May 2007

The general theory of the convergence of discretization algorithms founded by STUMMEL and GRIGORIEFF and later extended to nonlinear problems by numerous authors does not completely fit the numerical treatment of linear or nonlinear weakly formulated problems. Such an extension is presented together with examples of nonlinear elliptic and hyperbolic PDEs. Often the transition from classical to weak solutions leads to a loss of uniqueness such that uniqueness can only be guaranteed by additional conditions, e. g. suitable inequality constraints. How such constraints must generally be discretized in order to make the numerical solution converge to the corresponding unique weak solution is also discussed, and the results are particularly compared with entropy conditions of conservation laws. The examples are only treated in order to motivate the general theory and to demonstrate its applicability.
Unsteady Stokes Flow in a Distensible Pipe
Authors: Luchini P. , Lupo M. , Pozzi A.
Published: May 2007

In this paper the solution is presented of the problem of unsteady Stokes flow in a semi‐infinite distensible pipe, with initial conditions given at the pipe inlet. The solution is obtained through an eigenfunction expansion, utilizing Van Kampen's method for the determination of the expansion coefficients. In this way a complete description is obtained of the velocity and pressure profiles throughout the pipe.
Spatially Amplifying Waves in Plane Poiseuille Flow
Authors: Brevdo L.
Published: May 2007

The initial‐boundary‐value linear stability problem for two‐dimensional plane Poiseuille flow is treated by means of Fourier‐Laplace transform. Spatially amplifying waves in this flow are studied numerically for a wide range of Reynolds numbers R. It is shown that transition to turbulence may be accompanied by a selection of low frequencies in spatially amplifying nonstationary waves with small spatial undulations. No stationary spatially amplifying waves exist in this flow.
Monotonieerhaltende upwind‐Schemata im zweidimensionalen Fall
Authors: Kratsch F. , Roos H.‐G.
Published: May 2007

Standarddiskretisierungsverfahren sind zur Behandlung von konvektionsdominanten Problemen nicht geeignet, da insbesondere die Existenz von Grenzschichten zu Instabilitäten des diskreten Problems führt. Wir suchen nach einem einfachen, gleichmäßig stabilen Diskretisierungsverfahren der Ordnung 2 im zweidimensionalen Fall, für das im globalen Gebiet keine Ordnungsreduktion eintritt, wenn der Störungsparameter gegen Null geht. Es zeigt sich, daß es kaum möglich ist, bewährte Schemata vom eindimensionalen auf den zweidimensionalen Fall zu übertragen. Für eine spezielle upwind‐Technik jedoch kann die Inversmonotonie des diskreten Problems bewiesen werden.
Convergence of Discretizations of Nonlinear Problems. A General Approach
Authors: Ansorge R.
Published: May 2007

In 1948 Kantorovich published his famous paper on connections between Numerical Mathematics and Functional Analysis. Particularly for Numerical Analysis, the paper [31] of Lax and Richtmyer (1956) on the numerical treatment of (linear) partial initial value problems made Functional Analysis an instrument definitively adopted by numerical analysts.

A more general theory for the description and investigation of discretization methods – influenced by the Lax‐Richtmyer Theory and its extensions but not restricted to PDEs – was aroused by papers of Stummel in the 70s. A well developped Functional Analysis of Discretization Algorithms (Vainikko) came into being.

After a brief historical summary, some modern aspects of the theory will be discussed, e.g. a general access to the problem of convergence of approximate solutions to weak and not necessarily unique solutions of operator equations, discretization of entropy conditions, extension of the theory to problems where convergence of the numerical solutions to weak solutions can not be guaranteed in the sense of a norm topology but only in the sense of weak convergence or weak set convergence etc.

Concrete examples demonstrate the applicability of the theory.
Management and Control of Turbulent Shear Flows
Authors: Fernholz H. H.
Published: May 2007

This survey will begin with a few historical aspects, describe some passive and active management methods, and discuss selected examples of manipulation of leading edge separation. It will then deal with some typical flow phenomena which are important for the manipulation of turbulent shear flows. A display of active means to manipulate open separation will be followed by a practical example of forcing a separated boundary layer to reattach and to form a closed reverse‐flow region. The survey will end with a few remarks on control.
Bifurcation of the Cubic Map Related to Numerical Errors of a First‐Order Differential Equation
Authors: Klepp H. J.
Published: May 2007

It is shown that the one‐ and two‐dimensional cubic maps can be considered as formulae for the determination of approximations for the solution v = v(t) of the differential equation dv/dt = ‐v(v2 ‐ 1) established with the polygon and mixed polygon method. Periodical and irregular behaviour of the iterates vk of these formulae occur because of the weak stability of these methods, due to too large integration steps, and as a result of starting errors. These properties of the iterates vk are properties of the numerical errors ϵk = v(tk) − vk, too.
Analysis of Small Vibrations of Coupled Fluid‐Structure Systems
Authors: Wandinger J.
Published: May 2007

The article deals with the non‐selfadjoint eigenvalue problem arising in the analysis of linear vibrations of coupled fluid‐structure systems when the fluid is described by its pressure filed. First the completeness of the eigenvectors is verified. Then a simple relationship between the eigenvectors of the original problem and those of the adjoint problem is derived. To solve the eigenvalue problem a subspace iteration procedure is presented. The results are also extended to systems with rigid body motions and constant pressure fields.
A General Solution Technique for Piezothermoelasticity of Hexagonal Solids of Class 6mm in Cartesian Coordinates
Authors: Ashida F. , Tauchert Th. R. , Noda N.
Published: May 2007

Piezoelastic materials have attracted considerable recent attention because of their potential use in “intelligent” structural systems. In this paper, we propose a general solution technique for three‐dimensional problems of piezothermoelasticity for hexagonal solids of class 6mm in cartesian coordinates. Potential functions are introduced to represent the coupled elastic and electric fields. Simple uncoupled governing equations for the potential functions are derived from he stress equations of is analyzed. Numerical calculations for the stresses and the electric potential are carried out for a cadmium selenide body exhibiting class 6mm symmetry. Stress distributions are compared with those obtained for the similar thermoelastic problem without the piezo‐effect.
Analytical Solutions and a Numerical Algorithm for the Gauss's Hypergeometric Function 2F1 (a, b; c; z)
Authors: Mayrhofer K. , Fischer F. D.
Published: May 2007

The paper deals with the derivation of the analytical solution of a definite elliptical integral of general type which appears in fracture mechanics. The closed‐form solution is expressible in terms of the Gauss hypergeometric series 2F1 (a, b; c; z). As an alternative, the authors further present a suitable set of recurrence formulas and the accompanying starting solutions. Their application leads to other closed‐form expressions for the elliptical integral which are offered in the Appendix. Therefore, as a new result, analytical expressions are given for the Gauss hypergeometric series 2F1 (a, b; c; z) for specific parameters a, b, c. A powerful algorithm for the numerical computation of 2F1 has been developed.
A Preconditioning of the Tau Operator for Ordinary Differential Equations
Authors: Cabos Ch.
Published: May 2007

Für den Operator, der bei der Chebyshevschen Tau‐Methode för lineare gewöhnliche Differentialgleichungen auftritt, wird mittels eines Integral‐Operators eine Faktorisierung angegeben. Der erste Faktor dieser Faktorisierung hat eine beschränkte Konditions‐Zahl und ist schwach besetzt, falls die Koeffizienten in der Differentialgleichung Polynome niedriger Ordnung sind. Der zweite Faktor der Faktorisierung kann leicht direkt invertiert werden. Somit wird die iterative wie auch in vielen Fällen die direkte Lösung der Tau‐Gleichung für Differentialgleichungs‐Systeme vereinfacht. Darüber hinaus kann unter Verwendung dieser Faktorisierung ein Existenz‐ und Konvergenzbeweis für die Tau‐Approximation gegeben werden. Ein ähnlicher Präkonditionierer kann für Kollokationsgleichungen definiert werden. Numerische Beispiele, bei denen iterative Löser angewendet werden, zeigen verbesserte Konvergenz sowohl für die Tau‐Methode als auch für die Kollokationsmethode.
Subharmonic Vibrations and Onset of Chaos in Driven Asymmetric Oscillators
Authors: Schmidt G. , Seisl M.
Published: May 2007

Asymmetrische Oszillatoren treten in Mechanik, Physik und Technik auf, Beispiele sind asymmetrische Schwingungen von Schalen, gekrümmten Stäben, Pendelsystemen, Josephson‐Kontakten, SQUIDs und hängenden Kabeln. –‐ Es wird gezeigt, daß subharmonische asymmetrische Schwingungen und das Einsetzen von Chaos auf dieselbe Weise wie symmetrische Schwingungen untersucht werden könen, allerdings entstehen stets Komponenten mit geraden Harmonischen und konstante Komponenten von Anfang an, so daß die Analyse viel komplizierter ist. Beispiele unterstreichen den großen Einfluß der Asymmetrie.
Iteration of Runge‐Kutta Methods with Block Triangular Jacobians
Authors: van der Houwen P. J. , Sommeijer B. P.
Published: May 2007

We shall consider iteration processes for solving the implicit relations associated with implicit Runge‐Kutta (RK) methods applied to stiff initial value problems (IVPs). The conventional approach for solving the RK equations uses Newton iteration employing the full righthand side Jacobian. For IVPs of large dimension, this approach is not attractive because of the high costs involved in the LU‐decomposition of the Jacobian of the RK equations. Several proposals have been made to reduce these high costs. The most well‐known remedy is the use of similarity transformations by which the RK Jacobian is transformed to a block‐diagonal matrix the blocks of which have the IVP dimension. In this paper we study an alternative approach which directly replaces the RK Jacobian by a block‐diagonal or block‐triangular matrix the blocks of which themselves are block‐triangular matrices. Such a grossly ‘simplified’ Newton iteration process allows for a considerable amount of parallelism. However, the important issue is whether this block‐triangular approach does converge. It is the aim of this paper to get insight into the effect on the convergence of block‐triangular Jacobian approximations.
Inequality Forms of D'Alembert's Principle in Mechanics of Systems with Holonomic Unilateral Constraints
Authors: Goeleven D. , Panagiotopoulos P. D. , Lebeau C. , Plotnikova G.
Published: May 2007

This paper concerns the study of superpotential laws in analytical mechanics which may be derived from generally non‐everywhere differentiable energy functions through subdifferentiation. A generalization of d'Alembert's principle is proposed dealing with problems involving unilateral constraints.
Optimal Design of an Elastic Plate with Unilateral Elastic Foundation and Rigid Supports, Using the Reissner‐Mindlin Plate Model. II: Approximate Problems
Authors: Hlaváček I. , Lovíšek J.
Published: May 2007

Approximate optimal design and weight minimization problems are proposed, making use of mixed‐interpolated finite elements methods. The design variables — i.e., the thickness of the plate and the stiffness of the foundation are approximated by piecewise affine functions. The solvability of the approximate problems is proved and some convergence analysis is presented.
Magneto‐Micropolar Fluid Motion: On the Convergence Rate of the Spectral Galerkin Approximations
Authors: Rojas‐Medar M. A.
Published: May 2007

In this work we study error estimates and their respective convergence rates for approximate solution of spectral Galerkin type for the equations of motion of a magneto‐micropolar fluid in a bounded domain. We find error estimates that are optimal in the H1‐norm as well as estimates in the L2‐norm with improved rate with respect to the one immediately derived from the previous H1‐error estimate.
Thermal Buoyancy Convection in Vertical Zone Melting Configurations
Authors: Bárwolff G. , König F. , Seifert G.
Published: May 2007

A numerical method has been performed to explain and interpret oscillating convection phenomena in the vertical zone melting technique. The governing equations are solved in a cylindrical coordinate system using the finite volume method. The thermal boundary conditions were taken from experimental data. The aspect ratio or was varied within the range of 1 ⩽ ar ⩽ 3. Two‐dimensional calculations with application of parabolic boundary temperature show always steady axisymmetric behaviour of the convection. Only the three‐dimensional calculation yields the transition to non‐axisymmetric, time‐dependent (unsteady) flow. Furthermore the necessity of using thermal boundary conditions by a heat flux density q instead of a fixed parabolic temperature profile was demonstrated. The torus‐like flow changes at ar ≃ 1.45…1.5 to a single roll flow pattern. This single roll shows an unsteady behaviour with increasing aspect ratios and Rayleigh numbers, respectively. The comparison of the numerical results with experimental data shows a good qualitative correlation.
Polymers derived from 9,10‐dihydroxystearic acid
Authors: Morriss F. V. , Bechtle G. F. , Gadberry H. M.
Published: May 2007

A number of film forming polyester resins have been produced from 9,10‐dihydroxystearic acid. The resins cured readily at room temperature when crosslinked with 20% toluene diisocyanate to form flexible films. The properties of the films indicated that useful, internally plasticized polyester resins can be readily obtained from condensations of 9,10‐dihydroxystearic acid and polybasic acids. Maleic anhydride derived films gave the most desirable propertios.
Regeneration of carbonyl compounds from 2,4‐dinitrophenylhydrazones with sulfuric acid
Authors: Bassette Richard , Day E. A.
Published: May 2007

A simple, rapid method employing sulfuric acid and water to regenerate earbonyl compounds from 2,4‐dinitrophenylhydrazones is presented. The method was evaluated by using a number of DNP‐hydrazones of alkanals, alkan‐2‐ones, and 2‐alkenals and was found to give recoveries ranging from 23 to 61%. The procedure makes possible rapid organoleptic observations and is well adapted for recovery of the free carbonyl compounds for other studies.
Preparation of petroselinic acid
Authors: Fore Sara P. , Holmes Raiford L. , Bickford W. G.
Published: May 2007

Petroselinic acid of a grade which is suitable for most laboratory applications has been prepared by a single crystallization of the mixed fatty acids of parsley seed oil from 90% ethanol. A product of higher purity has been prepared from this acid by application of urea segregation techniques for the removal of saturated materials. No evidence of the presence of unsaturated fatty acids other than petroselinic acid was found in either of these samples when their ozonolysis products were examined chromatographically. On the basis of iodine values, assuming the absence of other unsaturated materials, the purities of the two preparations are 96.0 and 99.4%.
Evidence for cyclic monomers in heated linseed oil
Authors: Macdonald J. A.
Published: May 2007

The monomeric, non‐urea‐adduct‐forming material from the ethanolysis of heated linseed oil exhibits an infrared absorption band at 660 cm.−1 (15.2 μ). This absorption is not present in the spectrum of the esters of unheated linseed oil acids or in that of the adduct‐forming esters prepared from heated linseed oil. The monomeric, non‐urea‐adduct‐forming material, on aromatization and oxidation, yielded about 1% of phthalic anhydride, thus providing chemical evidence for the existence in this material of a compound containing an unsaturated six‐membered ring.
The chemistry of polymerized oils. V. The autoxidation of methyl linoleate
Authors: Sephton H. H. , Sutton Donald A.
Published: May 2007

1. The geometrical forms obtained during autoxidation of methyl linoleate at ordinary temperatures are largely conjugatedcis‐trans andtrans‐trans as shown by previous workers; there is a possibility that conjugatedcis‐cis forms are also produced.

2. Thetrans‐trans molecules arise partly, at least, by thermal rearrangement of already formedcis‐trans peroxide.

3. Some proportion, at least, of thecis‐trans molecules have theirtrans double bonds nearest to the hydroperoxide group.

4. A partial separation of the geometrical forms can be accomplished by reversed phase partition chromatography both on methyl linoleate hydroperoxides and on the corresponding mixed hydroxy compounds; isolation of thetrans‐trans forms can be accomplished in the latter case by urea complex fractionation.

5. No position isomers except the known 9‐ and 13‐isomers have been positively identified; there is a possibility that very minor amounts of the 2‐isomer are formed; the 9‐ and 13‐isomers are present in about equal amounts; the 11‐isomer was not detected by the methods applied.

6. Various ways in which the linoleate autoxidation problem might be advanced further are suggested.
Semimicro determination of total fatty acids and unsaponifiable matter
Authors: Benedict James H.
Published: May 2007

A semimicro method for determining both total fatty acids and unsaponifiable matter in fats, fatty acids, and soap is presented. The procedure involves saponification and recovery of the total fatty acids (which includes the unsaponifiables), removal of the fatty acids with anion exchange resins, and determination of the unsaponifiable matter by weight.

The total fatty acid method was evaluated on seven samples and showed a standard deviation from the mean of 0.21%. The unsaponifiable matter determination gives good reproducibility with a standard deviation from the mean of 0.06%. Since this ion exchange is a direct determination of the nonionic components, the results obtained from it should be more accurate and more nearly the true values than the macro extraction method which is empirical.
Continuous refining of crude coconut oil in a pressure system
Authors: Sullivan Frank E.
Published: May 2007

Conclusion

A continuous proces for refining crude coconut oil has been described. This Hermetic system provides a means for continually controlling the variables of time, temperature, and reagent on a scientific, predictable basis. By utilizing the phase diagram as a guide for the correct conditions and employing a continuous process designed to maintain these conditions, it is always possible to obtain high yield refining results on crude coconut oil.
Reactions of tertiary butyl hypochlorite with vegetable oils and their derivatives. V. Dechlorination of chlorinated soybean oil with aqueous solutions of salts
Authors: Teeter H. M. , Myren R. A.
Published: May 2007

Drying oils have been prepared by dechlorination of chlorinated soybean oil with aqueous solutions of basic salts such as sodium bicarbonate, sodium acetate, disodium hydrogen phosphate, and sodium tetraborate. These drying oils may prove useful in paints and varnishes.
Trends in the oilseed industry
Authors: Goss Warren H.
Published: May 2007

Conclusions

It is hardly feasible to mention here a host of additional trends now apparent in our industry. Neither is it possible to foresee with sufficient clarity the importance that will be attached one year or ten years hence to those trends which we have just discussed. By a thorough study of these however, including the economic situation responsible for them and the effects they will have on the oilseed and oil markets, we can formulate some insight into the course of the oilseed industry in the years ahead. We hope that this discussion, when viewed in retrospect next year or at a future date, will prove to have been accurate in at least some respects as an indieator of future developments.
Standardization of spectrophotometric methods for determination of polyunsaturated fatty acids using pure natural acids
Authors: Brice B. A. , Swain M. L. , Herb S. F. , Nichols P. L. , Riemenschneider R. W.
Published: May 2007

Spectrophotometric methods of analysis for the polyunsaturated constituents of oils and fats have been carefully restandardized for several conditions of alkali‐isomerization, using purified methyl esters of linoleic, linolenic, and arachidonic acids prepared by physical rather than by chemical means. A number of vegetable oil and animal fat samples were subjected to spectrophotometric analysis, and the results based on natural and on bromination‐debromination fatty acid standards were compared. The natural fatty acid standards lead to significantly higher accuracy and their use in the spectrophotometric analysis of natural fatty materials is strongly recommended. Results obtained under different conditions of isomerization were in satisfactory agreement. An isomerization time of 45 minutes is recommended rather than 25 or 30 minutes. The glycerol‐air technique is preferred for general use because of its simplicity and high precision. The ethylene‐glycol‐nitrogen technique is a close second choice because of the greater transparency of reagent blanks.
The chemistry of polymerized oils. I. Characteristics of some pilchard stand oil fractions
Authors: Joubert F. J. , Sutton Donald A.
Published: May 2007

Present‐day knowledge of the composition and mode of formation of stand oils is briefly reviewed.

One pilchard stand oil of low viscosity has been separated by molecular distillation into non‐polymeric and polymeric triglycerides.

The non‐polymeric triglycerides contain, a very low proportion of fatty acid chains linked together in contradiction of a published hypothesis.

The polymeric triglycerides have been separated into three broad sub‐fractions, the number average molecular weights of which have been determined by an isothermal distillation method.

The polymeric triglyceride sub‐fraction of lowest molecular weight was shown to contain an appreciable proportion of linked fatty acid chains.
Carbohydrate constituents of soybean “lecithin”
Authors: Scholfield C. R. , Dutton Herbert J. , Dimler Robert J.
Published: May 2007

The carbohydrates present in commercial soybean lecithin consist of two types: free sugars which can be removed by extraction with 55% alcohol, and bound sugars which remain with the phosphatides. The free sugars consist mainly of sucrose and stachyose with a smaller amount of raffinose. Upon extraction of phosphatides with absolute alcohol, the sucrose is found mainly in the absolute alcohol‐soluble fraction, the stachyose in the insoluble fraction, and the raffinose in both fractions.

The greater part of the bound sugars are found with that phosphoinositide fraction which is more hexane soluble. These bound sugars consist of galactose, mannose, and arabinose. The arabinose is easily freed by mild acid hydrolysis and all three sugars are freed by refluxing with 2 N H2SO4. The same three sugars together with a smaller amount of an unidentified sugar are found in the corresponding fraction of corn phosphatides. In the absolute alcohol‐soluble fractions of both soy and corn phosphatides the bound sugar consists of glucose and galactose.
Reactions of tertiary butyl hypochlorite with vegetable oils and their derivatives. VII. Partial chlorination of soybean oil
Authors: Teeter H. M. , Bell E. W. , Woods L. C.
Published: May 2007

Soybean oil has been partially chlorinated by treatment with from 0.1 to 1.0 equivalent oft‐butyl hypochlorite per equivalent of oil. The products were dechlorinated by autoclaving with aqueous sodium acetate solution, and the stability of the residual halogen in the dechlorinated oils was determined by a heat test.

It was found that oils halogenated with 0.5 equivalent or less of hypochlorite were more completely dechlorinated than those halogenated with larger amounts of hypochlorite and that the residual halogen in the dechlorinated oils produced was more stable.
The centrifugal acetone foots test applied to crude soybean oil. II. Rapid method compared with other measures of phosphatides content and refining loss
Authors: Freyer Egbert , Shelburne Victor
Published: May 2007

Comparisons are made between eight methods of grading crude soybean oil with respect to a laboratory refining loss determination which closely simulates commercial wash kettle practice. This list of methods includes the five analysis factors, acetoneinsoluble, HCl heat break, centrifugal foots, phosphorus and ash contents, each combined with percentage of ffa and moisture and volatile. It includes the official A.O.C.S. cup loss, the Wesson loss, and the chromatographic absorption loss determinations. On 12 crudes on which laboratory wash extraction loss and losses determined from centrifugal foots values, from acetone‐insoluble contents, and from HCl break values were available, the centrifugal foots values best predicted the refining loss. The standard deviations of each method from the wash extraction loss were, respectively, 0.21%, 0.27%, and 0.29%. On seven of these crudes on which all nine determinations were available, acetone insoluble content showed the best correlation, followed by centrifugal foots and HCl heat break. The centrifugal foots test generally gives zero or trace results on degummed oil. By use of this method however the refining loss grade of crude soybean oils may be estimated in as little as one hour of elapsed time, and it requires only 5 to 10 minutes of the operator's time.
The iodine number of lanolin
Authors: Punnett P. W. , Rebarber A.
Published: May 2007

Conclusion

The determination of the iodine value of U.S.P. anhydrous lanolin is an empirical one. Very close attention is necessary to the various factors concerned in the determination, sample weight, Hanus reagent strength, time, and temperature.

The addition of mercuric acetate will speed up the iodination markedly, but again details of the determination will have to be determined.
Application of urea complexes in the purification of fatty acids, esters, and alcohols. I. Oleic acid from inedible animal fats
Authors: Swern Daniel , Parker Winfred E.
Published: May 2007

Urea complex formation has been employed in the preparation of purified oleic acid (oleic acid content, 80–95%) from various grades of inedible animal fats and red oils. Since the urea complex of oleic acid forms in good yield at room temperature, low temperatures are not required in the isolation procedure. Yields of oleic acid are equal to or lower than those obtained by conventional low‐temperature crystallization procedures, but the preparation of a polyunsaturate‐free oleic acid is apparently not possible by urea complex formation alone. The separation of polyunsaturated acids from oleic acid by urea complex formation is more convenient than but not as efficient as by solvent crystallization, but separation of saturated acids from unsaturated acids is less convenient.

Advantages and disadvantages in using urea in the preparation of purified oleic acid are briefly discussed.
Pilot plant desolventization of fine cottonseed meal
Authors: Graci A. V. , Gardner H. K. , Cucullu A. F. , Crovetto A. J. , Spadaro J. J. , Knoepfler N. B.
Published: May 2007

The continuous desolventization of fine cotton‐seed meal has been successfully accomplished in a modified pilot‐plant meal dryer of the screw‐conveyor type under controlled conditions. The work should also have application in commercial solvent‐extraction where a general fines problem (1) exists.

Free gossypol content has been reduced as much as 69% during the desolventization operation without appreciably affecting the protein solubility of the meal.

A meal in granular form can be obtained, provided the feed material has certain physical characteristics. This granulation, or essentially pelleting, effect should have application particularly in nutritional work where the feeding of meal in pellet form of various sizes is required. It is believed that a number of conditions contributed to the granulation. The most important was probably the high density of the material which was fed in a compressed or extruded form. It is likely that the fineness of the material, the moisture content, and the solvent content contributed to this consolidation during desolventization, but the quantitative effect of these variables has not been determined. It is thought that any material that can be made to hold together during the initial part of the desolventization will tend to produce a granulated product at the end of the drying period.
Trans‐octadecenoic acid content of beef fat. Isolation of elaidic acid from oleo oil
Authors: Swern Daniel , Knight H. B. , Eddy C. Roland
Published: May 2007

Infrared spectrophotometric examination of three samples of freshly‐rendered edible beef fat, and of edible oleo oil and oleo stearine obtained from one of them, has revealed the presence of substantial quantities (5 to 10%) of trans materials believed to the mainly, if not exclusively, monounsaturated. It has been concluded that the trans components are neither minor nor adventitious constituents but important naturally‐occurring components which may contribute to any unique properties which beef fat may have.

It is proposed that trans‐octadecenoic acids arise in beef fat as a result of an oxidative cis‐trans isomerization coupled with double bond shift, reactions now known to occur in oxidizing fat systems, or by a simple oxidative cis‐trans isomerization without double bond shift of oleic or other isomeric cis‐octadecenoic acids which may be present in beef fat.

Trans‐9‐octadecenoic (elaidic) and vaccenic acids have been isolated from oleo oil, the former‐acid apparently for the first time.
Pre‐treatment of peanut kernels for effective skin removal
Authors: Pominski J. , D'Aquin E. L. , Molaison L. J. , McCourtney E. J. , Vix H. L. E.
Published: May 2007

A new method for the removal of skins from peanut kernels by water‐treatment, drying, and blanching in a standard split‐nut blancher has been developed on a pilot‐plant scale. Optimum conditions for approximately 98% skin removal from U. S. No. 1 shelled Spanish peanuts by this method are water‐treatment at room temperature, to gain not less than 20%, drying with forced circulated air at 120° to 125°F. to approximately 4.5% moisture in the peanuts, and blanching. The lipids and protein losses resulting from the water‐washing action on the kernels were relatively low and less than those losses obtained by lye treatment of the kernels. The method however did not give satisfactory results with either shelled U. S. No. 2 or oil mill stock kernels.

Meal prepared by hexane extraction of de‐skinned (98%) water‐treated U. S. No. 1 kernels had color and flavor characteristics superior to other hexane solvent‐extracted peanut meals for food utilization. Protein prepared from this meal had a light color equal to that produced from peanut kernels treated with 0.5% lye solution.
Relation between fatty acid composition and iodine value of cottonseed oil
Authors: Stansbury Mack F. , Hoffpauir Carroll L.
Published: May 2007

The regularity in the increase in linoleic, and in the decrease in oleic and saturated acids with increase in iodine value of cottonseed oils has been shown by obtaining the regression equation for the glyceride of each acid on the iodine value by use of the compositional data on 48 samples of oil ranging from 89.8 to 117.0 in iodine value. These equations offer a ready means of approximating the fatty acid composition of cottonseed oils from their iodine values. Such approximations may prove useful in the segregation of oils for different end uses.

The compositional pattern of cottonseed oils is compared with those reported in the literature for soybean and linseed oils.
The glycerolysis of fat in tertiary aromatic nitrogeneous bases to increase monoglyceride yield
Authors: Mattil Karl F. , Sims Rex J.
Published: May 2007

A method has been described for producing monoglyceride concentrates containing up to 78% of monoesters. It involves the interaction of fat with glycerol in a tertiary aromatic nitrogenous base such as pyridine, β‐ or γ‐picoline, 2,6‐lutidine, quinoline, or iso‐quinoline, and employs an alkaline interesterifieation catalyst such as sodium methoxide.
Metabolic effects of selenium as related to vitamin E
Authors: Bieri J. G. , Andrews E. I.
Published: May 2007

Trace amounts of dietary selenium, which prevent certain vitamin E deficiency symptoms, have been found to affect the composition of chick tissues. Both selenium and vitamin E increased liver coenzyme A levels to normal when cystine was omitted from the diet. Liver and plasma total fatty acids were unaltered by selenium but vitamin E increased the arachidonic acid content slightly. There was no effect of either selenium or vitamin E on total lipid, cholesterol, phopholipid or coenzyme Q in liver. Low dietary levels of either selenium or vitamin E, which were insufficient in preventing deficiency symptoms, completely eliminated mortality from toxic amounts of a dietary antioxidant. The ability of dietary selenium to reducein vitro lipid peroxidation in chick liver homogenates was not demonstrable with rat liver.