bluuebunny/crossref_metadata_2025 huggingface dataset:
Über die Lösung des St.‐Venantschen Torsionsproblems durch singuläre Randintegralgleichungen
Authors: Zlatanovski T.
Published: May 2007

Singuläre Integralgleichungen wurden bislang fast nicht zur Lösung des klassischen St.‐Venantschen Torsionsproblems angewandt. In dieser Arbeit wird das Problem auf direkte Weise in eine singuläre Randintegralgleichung überführt, und dann werden die Bedingungen zu deren eindeutiger Lösung (auch im Falle mehrfach zusammenhängender Stabquerschnitte) angegeben. An einem Beispiel wird gezeigt, daß diese singuläre Randintegralgleichung in manchen Fällen auch zur exakten analytischen Lösung des Torsionsproblems gut geeignet ist.
A Finite‐Rotation Theory for Elastic‐Plastic Shells under Consideration of Shear Deformations
Authors: Bašar Y. , Weichert D.
Published: May 2007

A consistent, five‐parametric shell theory which permits the consideration of transversal shear deformations is developed for elastic‐plastic analysis of shells undergoing finite rotations. The constitutive equations derived allow the consideration of isotropic and kinematic hardening with temperature dependent yield limit and deliver as special case the Prandtl‐Reuss equations. For the application of incremental‐iterative solution strategies, the field equations, in particular, the principle of virtual work are transformed into incremental equations. The constitutive relations are given in terms of stresses rather than of the two‐dimensional force variables and present, thus, a suitable basis for the development of layered numerical models.
Zur numerischen Integration linearer zeitvarianter Systeme
Authors: Bergmann K.
Published: May 2007

Es werden 1‐ und 2‐stufige Runge‐Kutta‐Verfahren vom Gauß‐Typ vorgestellt, die speziell auf lineare zeitvariante Bewegungsgleichungssysteme zugeschnitten sind. Gegenüber anderen Algorithmen, die in diesem Zusammenhang angewendet werden, arbeiten sie theoretisch schneller, da ihr Rechenaufwand kleiner ist und sie absolut stabil sind.
Globale Stabilität und Umlauflösungen für ein System zweier gekoppelter Josephson‐Kontakt‐Gleichungen
Authors: Reitmann V.
Published: May 2007

Es wird eine Zwei‐Punkt‐Diskretisierung der gedämpften Sinus‐Gordon‐Gleichung untersucht, welche die Dynamik zweier gekoppelter Josephson‐Kontakte beschreibt. Unter Benutzung von Frequenzmethoden und Vergleichstechniken wird gezeigt, daß Oszillationen (Zyklen erster Art) nicht auftreten können. Es werden Parameterbereiche angegeben, für die Umlauflösungen existieren, und es werden Bedingungen formuliert, bei denen jede Lösung des Systems gegen einen stationären Punkt konvergiert.
On the Stability of an Elastic Imperfect Column Including Axial Compressibility
Authors: Guran A.
Published: May 2007

The nonlinear stability of a compressible elastic imperfect column under uniaxial compression is studied. It is shown that in addition to a stable symmetric bifurcation diagram, hysteresis, and a trifurcation may occur. Using a nonlinear finite element technique, numerical examples illustrating the imperfection sensitivity of an elastic compressible column in various ranges of slenderness ration are given. The present paper sheds new light on the question of the possibility of snap‐through buckling of a compressible column.
Influence of Shear Deformation and Rotatory Inertia on the Solutions of the Generalized Mathews Problem
Authors: Bogacz R. , Krzyżyński T. , Popp K.
Published: May 2007

The influence of shear deformation and rotatory inertia on the dynamics of a beam under a moving harmonic force is studied. Solutions in the whole range of parameters for the shear beam and the Rayleigh beam on elastic foundation are presented. The obtained results are compared with solutions for the Timoshenko beam and the Bernoulli‐Euler beam. The analysis makes it possible to determine separately the influence of shear deformations and rotatory inertia on the solutions of the generalized Mathews problem.
Two General Representation Theorems for Arbitrary‐Order‐Tensor‐Valued Isotropic and Anisotropic Tensor Functions of Vectors and Second Order Tensors
Authors: Xiao H.
Published: May 2007

In this paper, it is shown that irreducible representations for r‐th‐order‐tensor‐valued isotropic or anisotropic tensor functions depending on an arbitrary number of vectors and second order tensors as variables may be formed by the union of irreducible representations for certain r‐th‐order‐tensor‐valued isotropic or anisotropic tensor functions merely depending on not more than three variables (for r ≧ 1) or four variables (for r = 0) and hence that the representation problem for the former may be reduced to that for the latter.
Mixed Convective Conjugate Heat Transfer from a Vertical Flat Plate
Authors: Pop I. , Ingham D. B. , Yuan Y.
Published: May 2007

The aim of this paper is to present a detailed numericla study of the conjugate mixed convection flow along a vertical finite flat plate and both the cases of aiding and opposing flows, which are characterized by the buoyancy parameter λ, are considered. In the first part of the analysis, asymptotic series solutions which are valid near the leading edge of the plate and far from it are given. These solutions are them matched by solving numerically the full governing boundary‐layer equations using a finite‐difference scheme. It is shown that for λ < 0 (opposing flow) the boundary‐layer separates from the plate and we have determined very accurately the location of the point of separation, i.e. where the numerical method breaks down. In addition, an asymptotic expression is given which accurately predicts the position of separation as a function of the buoyancy parameter. Detailed velocity and temperature profiles, and the skin friction and the temperature at the plate are given for a wide range of values of the relevant parameters which occur in the problem.
Bruchbedingungen vom Mohrschen Typ für transversal isotrope Werkstoffe am Beispiel der Faser‐Kunststoff‐Verbunde
Authors: Jeltsch‐Fricker R.
Published: May 2007

In neuerer Zeit sind Kriterien zur Beschreibung des Bruchverhaltens de Matrix von unidirektionalen Faser‐Kunststoff‐Verbunden entwickelt worden, die auf der Mohrschen Bruchhypothese basieren. Die Mohrsche Bruchhypothese besagt in dem betrachteten Fall, daß der Bruchkörper durch seine orthogonale Projektion in einem dreidimensionalen linearen Unterraum des Spannungsraumes festgelegt ist. Die Gestalt des Projektionskörpers liefert damit Vorgaben für die Modellierung von Bruchbedingungen. Mit dem konstruktiven Verfahren zur Bestimmung der zum Bruch Führenden Spannungszustände werden gleichzeitig Richtungen ermittelt, in denen der Bruch auftreten kann.
Free Convection of a Non‐Newtonian Power‐Law Fluid from a Vertical Wavy Surface with Uniform Surface Heat Flux
Authors: Kumari M. , Pop I. , Takhar H. S.
Published: May 2007

The steady laminar free convection in the flow of a non‐Newtonian power‐law fluid along a vertical wavy surface with constant heat flux has been investigated in this paper. The transformed boundary layer equations are solved by using a very efficient implicit finite‐difference method. A sinusoidal surface is used to elucidate the amplitude of the wavy surface effects. Along with the wall temperature, representative velocity and temperature profiles are presented. Numerical results show that the wall temperature decreases as the power‐law index increases, while it increases with the amplitude of the wavy surface. Comparisons with earlier work are also made for a flat plate immersed in a Newtonian fluid. The results are found to compare very well.
Spectral Properties of a System Describing Fast Pulsating DFB Lasers
Authors: Rehberg J. , Rehberg J. , Wünsche H.‐J. , Bandelow U. , Wenzel H.
Published: May 2007

A model describing self pulsating distributed feedback semiconductor lasers is investigated with mathematical rigour. Qualitative statements on its spectral properties are proved.
On a Mathematical Model of a Radiating, Viscous, Heatconducting Fluid: Remarks on a Paper by J. Förste
Authors: Gergó L. , Stoyan G.
Published: May 2007

We consider a mathematical model of the fluid indicated in the title which is useful in describing several processes of industrial interest like gas flow in lighting devices or flow of molt glass in a glass furnace. This model includes the three‐dimensional Navier‐Stokes equations, mass conservation, and equations for radiation intensity (differential approximation) and temperature.

The problem is rewritten to define a weak solution the existence of which we re‐prove following a paper by J. Förste. For unicity of the solution we give a modified proof (under suitable conditions on the solution domain).
Modeling Nonlinear Viscous Incompressible Fluid Flows in Axisymmetric Complex Geometry
Authors: Zarutskaya T. V.
Published: May 2007

An effective approach to solving the problem of steady flow of incompressible nonlinear viscous fluid in arbitrary axisymmetric channels is introduced. We show how to reduce the problem to a variational one, and then how to find the saddle point of an appropriate functional. The relevant techniques are pointed out. We analyse some numerical results.
β‐blocked Multistep Methods for Euler‐Lagrange DAEs: Linear Analysis
Authors: Arévalo C. , Führer C. , Söderlind G.
Published: May 2007

Many different methods have been suggested for the numerical solution of index 2 and 3 Euler‐Lagrange equations. We focus on 0‐stability of multistep methods (φ, σ) and investigate the relations between some well‐known computational techniques. By various modifications, referred to as β‐blocking of the σ polynomial, some basic shortcomings of multistep methods may be overcome. This approach is related to projection techniques and has a clear and well‐known analogy in control theory. In particular, it is not necessary to use BDF methods for the solution of high index problems; indeed, “nonstiff” methods may be used for part of the system provided that the state‐space form is nonstiff. We illustrate the techniques and demonstrate the results with a simplified multibody model of a truck.
Effect of Injection on the Squeeze Flow in the Presence of a Magnetic Field
Authors: Usha R. , Sridharan R.
Published: May 2007

The squeeze flow of an electrically conducting fluid between two parallel disks with injection at the lower porous disk in the presence of a magnetic field applied perpendicular to the disk is investigated. Analytic solutions are obtained through the use of a regular perturbation scheme. The results show that the effect of injection is to increase the load carrying capacity in the hydromagnetic squeeze film and this increase is more than that observed without injection.
Proof producing synthesis of arithmetic and cryptographic hardware
Authors: Slind Konrad , Owens Scott , Iyoda Juliano , Gordon Mike
Published: May 2007

A compiler from a synthesisable subset of higher order logic to clocked synchronous hardware is described. It is being used to create coprocessors for cryptographic and arithmetic applications. The compiler automatically translates a functionfdefined in higher order logic (typically using recursion) into a device that computesfvia a four-phase handshake circuit. Compilation is by fully automatic proof in the HOL4 system, and generates a correctness theorem for each compiled function. Synthesised circuits can be directly translated to Verilog, and then input to design automation tools. A fully-expansive ‘LCF methodology’ allows users to safely modify and extend the compiler’s theorem proving scripts to add optimisations or to enlarge the synthesisable subset of higher order logic.
Telesurgery: Remote Knowledge Translation in Clinical Surgery
Authors: Anvari Mehran
Published: May 2007

Dissemination of new surgical knowledge, skills, and techniques across the wide spectrum of practicing surgeons in the community is often difficult and slow. This is even more problematic in countries such as Canada, where geographic distances separate a large portion of community surgeons from the large teaching centers. As an example, the penetration of advanced minimally invasive techniques in Canada has been severely hampered by the inability to provide adequate training opportunities and support for community surgeons, many of whom live in remote regions of the country. In an attempt to overcome the barriers that exist, the Centre for Minimal Access Surgery (CMAS) at McMaster University has been using broadband Internet and telecommunication systems to provide distance training and mentoring to community surgeons living in remote northern communities of Canada. This article describes our experience with telementoring and robot‐assisted remote telepresence surgery and assisting, between a teaching hospital in Hamilton and two community hospitals in northern Ontario and Quebec.
Tumor Localization for Laparoscopic Colorectal Surgery
Authors: Cho Yong Beom , Lee Woo Yong , Yun Hae Ran , Lee Won Suk , Yun Seong Hyeon , Chun Ho‐Kyung
Published: May 2007

Background

Because palpating colonic tumors during laparoscopy is impossible, the precise location of a tumor must be identified before operation. The aim of this study was to evaluate the accuracy of various diagnostic methods that are used to localize colorectal tumors and to propose an adequate localization protocol for laparoscopic colorectal surgery.

Methods

A total of 310 patients underwent laparoscopy‐assisted colectomy between April 2000 and March 2006. We investigated if the locations of the tumors that were estimated preoperatively were consistent with the actual locations according to the operation.

Results

All the tumors were correctly localized and resected. Altogether, 203 patients had complete endoscopic reports available. Colonoscopy was inaccurate for tumor localization in 23 cases (11.3%). In total, 104 patients (33.5%) underwent barium enema; five tumors (4.8%) were not visualized, and three tumors were incorrectly localized. Another group of 94 patients (30.3%) underwent computed tomography (CT) colonography, which identified 91 of 94 lesions (96.8%). Finally, 96 patients (31.0%) underwent endoscopic tattooing; 2 patients (2.1%) did not have tattoos visualized laparoscopically and required intraoperative colonoscopy to localize their lesions during resection. Dye spillage was found in six patients intraoperatively, but only one patient experienced clinical symptoms. Intraoperative colonoscopy was performed in four patients; two of the four were followed by endoscopic tattooing, and the other two underwent intraoperative colonoscopy for localization. All lesions were correctly localized by intraoperative colonoscopy. The accuracy of tumor localization was as follows: colonoscopy (180/203, 88.7%), barium enema (97/104, 93.3%), CT colonography (89/94, 94.7%), endoscopic tattooing (94/96, 97.9%), and intraoperative colonoscopy (4/4, 100%).

Conclusions

With a combination of methods, localization of tumors for laparoscopic surgery did not seem very different from that during open surgery. Preoperative endoscopic tattooing is a safe, highly effective method for localization. In the case of tattoo failure, intraoperative colonoscopy can be used for accurate localization.
Effects of Warm Water Sitz Bath on Symptoms in Post‐anal Sphincterotomy in Chronic Anal Fissure—A Randomized and Controlled Study
Authors: Gupta Pravin J.
Published: May 2007

Background

Sitz bath is frequently recommended by physicians for a variety of anal disorders including anal fissure. The aim of the present study was to determine whether sitz bath does have any therapeutic properties improving upon a patient’s postoperative symptoms after a closed lateral sphincterotomy.

Materials and Methods

Forty‐six patients were randomly assigned to receive analgesics and fiber supplement alone (control patients) or a twice‐daily sitz bath along with identical fiber and analgesics (sitz bath group). A 24‐h pain score—post‐defecation anal burning and symptom improvement—was evaluated on a visual analog scale (VAS).

Results

The groups were equally matched for age, gender distribution, and duration of disease. No significant difference in mean pain score between groups (p = 0.284) was noticed after one week. However, the patients from the control group experienced significant anal burning compared with patients from sitz bath group (p < 0.0001). The improvement score was higher in the sitz bath group when compared with the control group; however, it did not reached a statistically significant level.

Conclusions

Patients after sphincterotomy for anal fissure receiving sitz bath experienced similar levels of pain when compared with those not receiving sitz bath. However, they reported a significant relief in anal burning and a marginally better satisfaction score and no reported adverse side effects.
Similar Analgesic Effect after Popliteal Fossa Nerve Blockade with 0.375% and 0.75% Bupivacaine
Authors: Ya Deau Jacques T. , Wukovits Barbara U. , LaSala Vincent R. , Jules-Elysée Kethy M. , Paroli Leonardo , Kahn Richard L. , Levine David S. , Lipnitsky Jane Y.
Published: May 2007

This study tested the hypothesis that increasing the concentration of bupivacaine from 0.375 to 0.75% would increase the duration of postoperative analgesia by 3 h. Seventy patients scheduled for hospital admission after foot or ankle surgery gave consent to enter this prospective randomized trial. Patients were randomly assigned to receive a popliteal fossa block (posterior approach) using 30 cc of either 0.375% or 0.75% bupivacaine, with epinephrine. Patients also received a neuraxial anesthetic and postoperative intravenous patient-controlled analgesia. Patient characteristics, duration of analgesia, pain scores, use of analgesic medications, and side effects of analgesic therapy were determined. Duration of analgesia was similar with both concentrations of bupivacaine (0.375% 14 ± 8 h, 0.75% 13 ± 6 h; mean ± SD). Pain scores were the same for both groups on the first postoperative day (3 of 10 at rest, 5 with therapy). Analgesic use and side effects attributable to pain management did not differ between groups. In conclusion, postoperative analgesia was not affected by the concentration of bupivacaine used for the nerve block. There was no benefit to increasing the concentration of bupivacaine above 0.375% for single-injection popliteal fossa nerve blockade when performed for postoperative analgesia.
Stability to oxidation of virgin olive oils as related to olive conditions: Study of polar compounds by chemometric methods
Authors: Evangelisti F. , Zunin P. , Tiscornia E. , Petacchi R. , Drava G. , Lanteri S.
Published: May 2007

Polar compounds of virgin olive oils were analyzed. They influence oil flavor and aroma and improve the shelf‐life of the oil. The orthodiphenolic fraction is particularly significant for oil stability because of its antioxidative activity. A relationship between the composition of the whole fraction of polar compounds and the state of health of the olives was established. For this purpose, oil samples were obtained from olives that had reached different degrees of ripeness and that had been affected by Dacus oleae infestation differently. The polar compounds were then analyzed by high‐performance liquid chromatography. The data set was studied by means of chemometric methods. Partial least squares regression was used to obtain models that show a significant correlation between composition of the oil’s polar compounds and conditions of the olives sampled. In particular, compounds with antioxidative activity were directly linked with the state of health of the olives. The models obtained allow tracing of the state of health of the olives sampled through analysis of the polar fraction of virgin olive oil with a high degree of accuracy, and thus prediction of the oil’s expected shelf life.
Development and validation of fluorescence spectroscopic assays to evaluate antioxidant efficacy. Application to metal chelators
Authors: Arora Arti , Strasburg Gale M.
Published: May 2007

Two fluorescence‐based assays were developed for rapid evaluation of compounds for antioxidant activity. These assays were based on the quenching of intensity of the fluorescent probe and an increase in its fluorescence anisotropy due to the free radicals generated during lipid peroxidation. A large unilamellar vesicle system, containing the fluorescence probe diphenylhexatriene‐propionic acid, was used to study the effects of chelators on metal‐ion‐induced lipid peroxidation. In this paper, the actions of the chelating agents ethylenediaminetetraacetic acid disodium salt (EDTA), nitrilotriacetic acid trisodium salt (NTA), adenosine‐5′‐diphosphate disodium salt (ADP), and sodium citrate on Fe(II)‐ and Fe(III)‐induced peroxidation were compared. The effects of chelators on metal‐ion‐induced peroxidation depended on the type of metal used to initiate peroxidation and, for citrate, also on the concentration of chelator used. EDTA strongly suppressed both Fe(II)‐ and Fe(III)‐induced peroxidation in this system. NTA and ADP inhibited Fe(III)‐induced peroxidation but enhanced Fe(II)‐induced peroxidation at all concentrations tested. Citrate promoted both Fe(II)‐ and Fe(III)‐induced peroxidations at lower chelator‐to‐metal ratios; however, at higher ratios, it inhibited both peroxidations. The results of the two fluorescence‐based assays agreed well with the quantitation of conjugated dienes and hydroperoxides by high‐performance liquid chromatography. The combination of sensitivity, speed, and general utility associated with these methods suggests that these methods will be useful in rapid screening of extracts and purified compounds for antioxidant activity.
Quenching mechanism and kinetics of ascorbyl palmitate for the reduction of the photosensitized oxidation of oils
Authors: Lee K. H. , Jung M. Y. , Kim S. Y.
Published: May 2007

Effects of 0, 500, 1000, and 1500 ppm (wt/vol) ascorbyl palmitate (AP) on the methylene‐blue‐ and the chlorophyll‐sensitized photooxidations of linoleic acid or soybean oil, either in methanol or in a solvent mixture (benzene/methanol, 4:1, vol/vol), were studied during storage under 3300 lux fluorescent light for 5 h. Steady‐state kinetic approximation was used to determine a quenching mechanism and quenching rate constant of AP in the chlorophyll‐sensitized photooxidation of methyl linoleate in a solvent mixture (benzene/methanol, 4:1, vol/vol). Both methylene blue and chlorophyll greatly increased the photooxidation of linoleic acid and soybean oil, as was expected. AP was extremely effective at minimizing both methylene‐blue‐and chlorophyll‐sensitized photooxidations of linoleic acid and soybean oil, and its effectiveness was concentration‐dependent. The addition of 500, 1000, and 1500 ppm AP resulted in 69.3, 83.6, and 94.6% inhibition of methyleneblue‐sensitized photooxidation of linoleic acid, respectively, after 5‐h storage under fluorescent light. AP showed significantly greater antiphotooxidative activity than α‐tocopherol for the reduction of methylene blue‐sensitized photooxidation of linoleic acid (P < 0.05). The steady‐state kinetic studies indicated that AP quenched singlet oxygen only to minimize the chlorophyll‐sensitized photooxidation of oils. The calculated total quenching rate of AP was 1.0 × 108 M−1s−1. The present results clearly showed, for the first time, the effective singlet oxygen quenching ability of AP for the reduction of photosensitized oxidation of oils.
Collaborative test of determination of iodine value in fish oils. 2. Carbon tetrachloride or cyclohexane/acetic acid as solvents
Authors: Barlow Stuart M. , Bimbo Anthony P. , Miller Eric L. , Thorisson Snorri , Walters D. E.
Published: May 2007

Nine laboratories participated in a collaborative test to determine the iodine value (IV) of eight samples of fish oil (four with IV<150; four with IV>150) with either carbon tetrachloride (AOCS Official Method Cd 1–25) or cyclohexane/acetic acid (AOCS Recommended Practice Cd 1d‐92) as solvent and 1 h of reaction time. Laboratories received coded duplicate samples (hidden duplicates) and carried out duplicate determinations on each oil by each method (open duplicates). Replacing carbon tetrachloride with cyclohexane/acetic acid resulted in similar mean values for both low‐ and high‐IV oils and similar estimates of repeatability and reproducibility. The repeatability standard deviation (sr), based on hidden duplicates, with carbon tetrachloride and cyclohexane/acetic acid were 1.71 and 1.55, respectively. The corresponding reproducibility standard deviations were 1.81 and 1.98.
Capillary supercritical fluid chromatography‐atmospheric pressure chemical ionization mass spectrometry of triacylglycerols in berry oils
Authors: Manninen Pekka , Laakso Päivi
Published: May 2007

A capillary supercritical fluid chromatograph (SFC), combined with a triple‐quadrupole mass spectrometer (MS) via a liquid chromatography‐atmospheric pressure chemical ionization (LC‐APCI) interface, was utilized in the analysis of berry oil triacylglycerols. No modification of the commercially available interface was required. Vapor of different solvents, such as methanol, isopropanol, water, or ammonium hydroxide in methanol, was introduced in the sheath gas flow in the APCI source to achieve adequate ionization of triacylglycerols. The separation of triacylglycerols according to acyl carbon number and degree of unsaturation was accomplished on a 20 m × 50 µm i.d. SB‐Cyanopropyl‐25 column. The resolution of triacylglycerols in the reconstructed ion chromatogram and the sensitivity of the SFC‐(APCI)MS system was comparable to or slightly better than that obtained with a flame ionization detector. No baseline drifting was observed during the SFC density programming. Triacylglycerols formed diagnostic [M + H]+ and [M ‐ RCOO]+ ions with all tested reactant ion solvents except with ammonium hydroxide in methanol, which formed abundant [M + 18]+ ions instead of [M + H]+ ions. The abundance of the [M + H]+ ion increased with increasing degree of unsaturation of a triacylglycerol, whereas the abundance of the [M ‐ RCOO]+ ion depended on the regiospecific distribution of the fatty acid moiety between the sn‐1/3 positions and the sn‐2 position and on the number of double bonds.
Analysis of furanoid esters in soybean oil and the effect of variety and environment on furanoid ester content
Authors: Wu Xiangdong , Hammond Earl G. , White Pamela J. , Fehr Walter
Published: May 2007

An improved method was developed to analyze the major furanoid esters in soybean oil. The method is based on urea fractionation of the methyl esters, silver ion chromatography, and gas chromatography of the furanoid concentrate. Activation of the soybean lipoxygenase decreased the amount of furanoid ester recovered from the oil, but the degumming of crude soybean oil and the choice of solvent used to extract soybean lipids caused no change in furanoid ester content. Fifty‐six soybean varieties, representing a wide range in maturity group and geographical origin, were grown in Puerto Rico and used to determine the range of furanoid ester contents. Furanoid ester II ranged from 0.033–0.29 mg/g, and ester III ranged from 0.058–0.27 mg/g. The two major furanoid esters were positively correlated with each other and with maturity group. Growth environment as well as variety caused significant differences in furanoid content.
Extraction of coconut oil with Lactobacillus plantarum 1041 IAM
Authors: Che Man Y. B. , Abdul Karim M. I. B. , Teng C. T.
Published: May 2007

Extraction of coconut oil with a pure culture of Lactobacillus plantarum 1041 IAM was investigated. Grated coconut meat and water at 30, 50, and 70°C were mixed in various ratios (1:1, 1:2, and 1:3) and allowed to settle for 2–6 h. The most efficient coconut cream separation was obtained at the 1:1 ratio of grated coconut meat to water at 70°C, followed by 6 h settling time. Fermentation was then conducted on coconut cream emulsion with the sample from 1:1 ratio, 70°C, and 6‐h settling time. Oil yield from the fermentation process with 5% inoculum of L. plantarum 1041 IAM after 10 h at 40°C was 95.06% Quality characteristics of the extracted oil were as follows: moisture content, 0.04%; peroxide value, 5.8 meq oxygen/kg; anisidine value, 2.10; free fatty acid, 2.45%; iodine value, 4.9; and color, 0.6 (Y + 5R). Extraction of coconut oil from coconut meat with L. plantarum 1041 IAM was significantly improved in both oil yield and quality over the traditional wet process.
Acidolysis of several vegetable oils by mycelium‐bound lipase of Aspergillus flavus link
Authors: Long K. , Ghazali H. M. , Ariff A. , Bucke C.
Published: May 2007

The ability of mycelium‐bound lipase of a locally isolated Aspergillus flavus to modify the triglyceride structure of vegetables oils was studied. The catalysis involved the acidolysis of vegetable oils, such as palm olein, coconut oil, cotton‐seed oil, rapeseed oil, corn oil and soybean oil, with selected fatty acids (FA). The reactions were followed against time, and the percentages of FA incorporated were determined by gas chromatography. Percentage of FA incorporated after 20‐h reaction was in the range of 13 to 18%. Reaction between cottonseed oil with lauric acid gave the highest percentage of incorporation (18%), followed by soybean oil with lauric acid (16%) and coconut oil with oleic acid (16%). The results indicated that the hydrolytic affinity of A. flavus lipase demonstrates an acyl group specificity toward short‐chain FA (C8–C10). Changes in triglyceride profiles of each oil were also monitored by reverse‐phase high‐pressure liquid chromatography. In all products, there were increases in the concentrations of several existing triglycerides and formation of new triglycerides. The melting points of all acidolyzed vegetable oils were determined by differential scanning calorimetry, and significant changes in melting profiles were noted.
Comparative study of commercially available lipases in hydrolysis reaction of phosphatidylcholine
Authors: Hara Fumiko , Nakashima Toshimitsu , Fukuda Hideki
Published: May 2007

Nineteen commercial lipase preparations were compared with respect to their ability to hydrolyze phosphatidylcholine (PC) in a reverse micellar system. In terms of the source organism, lipases from Mucor or Rhizopus species showed comparatively high reactivity, while those from Aspergillus and Humicola sp. exhibited little PC hydrolysis activity. Almost no hydrolysis reaction was observed by positionally nonspecific lipases derived from Candida sp. The results suggest that particular attention should be paid to the source organism in selecting lipases for use in the enzymatic conversion of phospholipids.
Enzymatic esterification of θ‐3 fatty acid concentrates from seal blubber oil with glycerol
Authors: He Yuehua , Shahidi Fereidoon
Published: May 2007

Enzymatic synthesis of acyglycerols directly from glycerol and an θ‐3 fatty acid concentrate, prepared from seal blubber oil, in organic solvents was studied. Seven lipases were used as biocatalysts for esterification, Lipase LP‐401‐AS from Chromobacterium viscosum showed the highest activity for esterification. Effects of reaction parameters, namely, temperature, time course, type of solvent, water content, amount of glycerol, enzyme load and solvent volume, were followed with lipase IP‐401‐AS as the biocatalyst of choice. Optimal reaction conditions were established, and the maximal degree of acylglycerol synthesis reached was 94.3%. The concentrations of monoacylglycerols, diacylglycerols, and triacylglycerols were 13.8, 43.1, and 37.4%, respectively. Therefore, acylglycerols containing predominantly θ‐3 fatty acid concentrates may be easily synthesized directly via their reaction with glycerol.
Protease inhibitors and in vitro digestibility of karanja (Pongamia glabra) oil seed residue. A comparative study of various treatments
Authors: Rattansi Rabab , Dikshit Madhurima
Published: May 2007

Trypsin and chymotrypsin inhibitor activities (TIA and CIA) were assayed before and after processing of Karanja oil seed residue. Upon treatment, the loss of TIA and CIA varied with the type of processing or extraction: the reduction after solvent extraction ranged between 34 and 15%, respectively. These activities were completely removed in 2.4% HCl; 83.35 and 54.86% were removed on autoclaving; 33.86 and 15.30% on fermentation; and removal was 4.36–83.69% and 3.66–77.59% after exposure to different doses of gamma radiation (1, 5, 10, and 50 KGy). An in vitro digestibility study was carried out to confirm the inactivation of the inhibitors and showed improvements from 45 to 81%, with the maximum observed in 2.4% HCl solvent‐refluxed residue. A linear relationship was observed between the reduction in protease inhibitor activities and the improvement in digestibility.
Synthesis and properties of fish protein‐based hydrogel
Authors: Hwang Der‐Chyan , Damodaran Srinivasan
Published: May 2007

The novel use of fish protein (FP) in the manufacture of a superabsorbent hydrogel was investigated. Following the introduction of a large number of hydrophilic groups into fish protein by modification with ethylenediaminetetraacetic dianhydride (EDTAD), proteins were cross‐linked by sulfhydryl‐disulfide interchange reaction between the endogenous sulfhydryl groups and disulfide bonds to produce an insoluble gel structure. The water uptake of 76% EDTAD‐modified FP hydrogel was 540 g water/g dry gel at 214 × g, and it depended on pH and ionic strength of the solution. The structural changes in proteins consequent to modification were also investigated. EDTAD‐FP hydrogels had increased rigidity after glutaraldehyde treatment but displayed diminished water uptake characteristics.
Antioxidant activity of grape extracts in a lecithin liposome system
Authors: Yi Ock‐Sook , Meyer Anne S. , Frankel Edwin N.
Published: May 2007

Extracts of 14 different grapes were tested for their antioxidant activities in a copper‐catalyzed lecithin liposome oxidation assay and analyzed for their phenolic components by high‐performance liquid chromatography (HPLC). The total phenolic contents of the grape extracts varied from 176 to 1236 mg gallic acid equivalents (GAE)/L. Extracts of red wine grape varieties contained higher concentrations of phenolics than other varieties. When compared at the same 20 µM GAE basis, the grape extracts inhibited formation of conjugated diene hydroperoxides by 25.1 to 67.9%, and hexanal formation by 49.3 to 97.8%. Extracts of red table grape varieties Red Globe and Emperor and white wine grape varieties Chardonnay and Sauvignon Blanc gave the highest antioxidant activities. The relative percentage inhibition of conjugated dienes and hexanal correlated with total phenols (r=0.86 and 0.89). HPLC analyses showed that anthocyanins were the most abundant phenolic compounds in extracts of red grapes, and flavonols were most abundant in extracts of white grapes.
On the sub‐α‐form and the α‐form in monoacylglycerols
Authors: Watanabe Akihiro
Published: May 2007

The concentration of 2‐monostearoyl‐glycerol (2‐MS) in 1‐MS kept at 100°C reaches a plateau concentration of about 12% (w/w) according to 1H nuclear magnetic resonance. The phase diagram of these two components, made by differential scanning calorimetry (DSC), showed that the temperature of the transition from the sub‐α1‐form to the α‐form and the melting point of the α‐form decreased when the content of 2‐MS increased above 9%. The temperature of transition from the sub‐α2‐form to the sub‐α1‐form, however, decreased at even lower contents of 2‐MS. The reversible phase transition of mixtures of 2‐MS and 1‐MS from the sub‐α‐form to the α‐form has been followed by DSC and X‐ray diffraction. Concentrations of 2‐MS above 9% change the tilt of the molecules in the mixture abruptly during the transition from the sub‐α‐form to the α‐form. At higher temperature, the conformational disorder in the α‐form of the mixture changes continuously. This conformational disorder is, however, unstable enough to change gradually into a more stable one. Even for pure 1‐rac‐MS, small changes were observed. In addition, monobehenoyl‐glycerol and monopalmitoyl‐glycerol, which also contained 2‐monoacyl‐glycerol, were also investigated. The longer fatty acid chains tend to give a higher degree of conformational disorder. The transition behavior has been analyzed on the basis of the crystal structures. Water swelling behavior has also been studied and compared for the sub‐α‐form and the α‐form. The α‐form can incorporate more water, probably because it has more disordered polar groups.
Mixtures of palm kernel oil with cocoa butter and milk fat in compound coatings
Authors: Williams Sara D. , Ransom‐Painter Kelly L. , Hartel Richard W.
Published: May 2007

Thermal behavior of binary mixtures of palm kernel oil (PKO), cocoa butter (CB), and anhydrous milk fat was used to study mixed‐lipid crystallization. This study was related to the physical properties of compound coatings made with these fats. Phase behavior was studied by evaluating changes in melting behavior with composition and time, by creating isosolid diagrams, and by monitoring polymorphic behavior. For binary mixtures, multiple melting peaks and eutectic formation were observed for 30–50% addition levels of CB to PKO, but not for addition of milk fat to PKO. For compound coatings and binary mixtures, made with the same fat composition, hardness of compound coatings increased as solid fat content (SFC) at 25°C of binary mixtures increased. Also, as SFC at 25°C of the binary mixtures increased, induction time for bloom formation and time to fully bloom for compound coatings decreased. Observation of eutectic behavior for binary mixtures indicated softness in a compound coating with the same fat composition, but the converse was not necessarily true.
Surface and thermodynamic parameters of sodium N‐acyl sarcosinate surfactant solutions
Authors: Gad E. A. M. , El‐Sukkary M. M. A. , Ismail D. A.
Published: May 2007

Surface tension as a function of concentration and temperature was measured for solutions of N‐acyl sarcosinates, RCON(CH3)CH2COONa. From the intersection points in the (γ‐log c) curves, the critical micelle concentration (CMC) was determined at 20, 35, 50, and 65°C. Structural effects on the CMC, maximum surface excess, and the minimum area per molecule at the aqueous solution/air interface are discussed. The free energy, enthalpy, and entropy of micellization and adsorption of surfactant solutions also were investigated.
A bulky phosphite‐modified rhodium catalyst for the hydroformylation of unsaturated fatty acid esters
Authors: Muilwijk Koen F. , Kamer Paul C. J. , van Leeuwen Piet W. N. M.
Published: May 2007

A series of hydroformylation experiments was performed with a high‐grade and a technical‐grade‐derived methyl oleate (MO) and a rhodium catalyst modified by the bulky tris(2‐tert‐butyl‐4‐methylphenyl)phosphite. In the hydroformylation of pure methyl oleate, relatively high turnover numbers were obtained (400–500 mol/mol/h) under mild conditions (molar ratio MO/Rh=910, 80–100°C and 20 bar; CO/H2=1:1, solvent toluene), leading to about 95% conversion in 3 h. Fast isomerization occurs under these conditions to produce the trans oleate. Trans oleate reacts more slowly than cis oleate. At temperatures below 50°C, isomerization does not occur. The use of technical‐grade methyl oleate, containing 14% 9,12 diene, methyl linoleate (ML), results in lower reaction rates because dienes form stable π‐allylic intermediates, which slowly undergo hydroformylation. More severe conditions were applied to obtain higher rates. The rate varied from 50 to 400 mol/mol/h, depending on conditions (molar ratio MO/Rh=910, T=50–120°C, P = 50–80 bar; CO/H2=1:1–1:6, solvent, toluene). Several isomers of ML were formed during the reaction. Subsequent hydroformylation of these isomers results in a complicated mixture of products. The product mixture consists predominantly of methyl formylstearate, methyl formyloleate, methyl diformylstearate, and some yet unidentified side products. A comparison of the classic triphenylphosphine‐modified catalyst and the bulky phosphite‐modified catalyst has shown that the latter is several times more active.
Estolide production with modified clay catalysts and process conditions
Authors: Erhan Selim M. , Isbell Terry A.
Published: May 2007

The 20% yields of estolides prepared from oleic acid and meadowfoam oil fatty acids are improved when the montmorillonite clay catalysts are modified to increase their activity. Changes we explored included acidifying the clay, treating to increase the surface area of clay to introduce new active sites, and decreasing the ionic character of the clay surface to enhance adsorption of the fatty acids. We also evaluated the use of higher levels of clay in the reactions. Clays treated with Fe3+ salts increase the estolide yield from 21 to 27%, a 28% increase. Clay catalysts were also treated with surface‐active reagents. The most active were cationic surfactants, and montmorillonite clays treated with cetyltrimethylammonium chloride increased the estolide yield to 30%. Estolide yields could not be improved beyond 30% by increasing the amount of clay. However, nitrogen sparging increases the efficiency of stirring and increased the estolide yield to 35% estolide.
Enzymatic synthesis of estolides by a bioreactor
Authors: Yoshida Yasuko , Kawase Mitsuo , Yamaguchi Chozo , Yamane Tsuneo
Published: May 2007

An attempt was made to synthesize ricinoleic acid estolides effectively with a bioreactor system containing immobilized lipase. The optimal water content for reaction changed during synthesis of estolide from ricinoleic acid. The water content needs to be controlled to optimize conditions for each reaction stage and to prepare estolide with a high degree of condensation. The estolide synthesis was attempted to confirm if the reaction would have proceeded to the targeted degree of condensation by controlling the reaction mixture under the optimal water content. The result showed that, with the bioreactor, the reaction could proceed rapidly. A repeated batch reaction was possible in the bioreactor. The amount of lipase used can thus be highly reduced compared with discarding it each time. The loading density of enzyme onto the carrier greatly affected enzymatic activity, with a loading level of 60 mg lipase/g carrier producing 60% more estolide per gram of enzyme than a loading level of 120 mg/g. The estolide product synthesized in the bioreactor showed no coloration during the reaction process. This fact confirmed the validity of the proposed method.
Regular‐sized cell creation in microchannel emulsification by visual microprocessing method
Authors: Kawakatsu Takahiro , Kikuchi Yuji , Nakajima Mitsutoshi
Published: May 2007

A novel emulsification method was developed for making monodispersed regular‐sized cells. Both oil in water (O/W) and water in oil (W/O) emulsion cells were generated by permeating an internal phase into a continuous phase through a silicon microchannel, which was designed and prepared by using semiconductor technology. The microprocessing of O/W (or W/O) emulsion cells was monitored and controlled with a microscope video system. Regular‐sized O/W cells were made by a normal hydrophilic microchannel and a glass plate with use of an appropriate surfactant. On the other hand, W/O emulsion cells were made by a hydrophobic microchannel and a glass plate modified with a silane coupler reagent. Regular‐sized W/O cells were also obtained; therefore, a suitable combination of organic phase, surfactant, and electrolyte should be carefully selected. There is a possibility for creating artificial biological cells with this method. In the water/triolein and lecithin system, when the amount of oil was decreased on the permeate side, polygon or fiber cell types were created, and each cell contacted its neighbors across a thin oil layer like a biological tissue.
Effect of interesterification on the structure and physical properties of high‐stearic acid soybean oils
Authors: List G. R. , Mounts T. L. , Orthoefer F. , Neff W. E.
Published: May 2007

Triglyceride structures of genetically modified soybean oils high in stearic acid were determined by high‐pressure liquid chromatography, and their physical properties were assessed by dilatometry and dropping point. In their natural state, these oils lack sufficient solids at 10–33°C to qualify as margarine oils. However, after random interesterification, soybean oil containing 17% stearic acid shows a solid fat index (SFI) profile and dropping point closely matching those of a liquid margarine oil. Other oils, with stearic acid contents in the range of 20–33%, showed appreciable SFI values at 10°C but lacked sufficient solids at 21.1–33.3°C. After random interesterification, these oils also exhibited SFI profiles suitable for soft tub margarine, and their drop points increased from 18–19°C to 36–38°C.
Purification of docosahexaenoic acid by selective esterification of fatty acids from tuna oil with Rhizopus delemar lipase
Authors: Shimada Yuji , Sugihara Akio , Nakano Hirofumi , Kuramoto Takashi , Nagao Toshihiro , Gemba Munekazu , Tominaga Yoshio
Published: May 2007

To purify docosahexaenoic acid (DHA), we attempted the selective esterification of fatty acids originating from tuna oil with lipases. Tuna oil was hydrolyzed in NaOH‐ethanol solution, and the resulting fatty acid mixture [DHA, 23.2%; named tuna‐free fatty acid (FFA)] was used as a starting material. Rhizopus delemar which acted lightly on DHA, was a suitable catalyst for the selective esterification of tuna‐FFA, and lauryl alcohol was the best substrate. The reaction proceeded most effectively when a mixture of 2.4 g lauryl alcohol/tuna‐FFA (2:1, mol/mol), 0.6 g water, and 600 U Rhizopus lipase was incubated at 30°C for 20 h with stirring at 500 rpm. Under these conditions 72% of tuna‐FFA was esterified, and 84% of DHA was recovered in the unesterified fatty acid fraction. The DHA content in the fatty acid fraction rose from 23 to 73% with this reaction. To further elevate the DHA content, the unesterified fatty acids were extracted, and then esterified again under the same conditions. By this repeated esterification, DHA was purified to 89% with a recovery of 71% of its initial content.
Determination of mixtures in vegetable oils and milk fat by analysis of sterol fraction by gas chromatography
Authors: Alonso L. , Fontecha J. , Lozada L. , Juárez M.
Published: May 2007

A rapid gas‐chromatographic (GC) procedure was developed for the analysis of the total sterol fraction of vegetable oils, milk fat or mixtures, to detect possible admixtures of sunflower with olive oil and the addition of vegetable oils to milk fat. The method, which employs alkali‐catalyzed transesterification with KOH/methanol, was compared with saponification procedures with and without transformation of sterols into silyl derivatives prior to analysis. Repeatability of the method was assessed, and the coefficient of variation was 6.0 and 8.0% for β‐sitosterol in olive and sunflower oils, respectively. Recovery of β‐sitosterol ranged from 92.6 to 95.8 for both oils. The GC method assayed in this work requires little analysis time and eliminates the need for saponification, extraction, and derivatization steps. It offers good repeatability and recovery and is thus well suited to routine use.