bluuebunny/crossref_metadata_2025 huggingface dataset:
Theory and finite element computation of cyclic martensitic phase transformation at finite strain
Authors: Stein Erwin , Sagar Gautam
Published: August 2007

A generalized variational formulation, including quasi‐convexification of energy wells for arbitrarily many martensitic variants in case of mono‐crystals for linearized strains, was developed by Govindjee and Miehe (Comp. Meth. Appl. Mech. Eng. 2001; 191(3–5):215–238) and computationally extended by Stein and Zwickert (Comput. Mech. 2006; in press). This work is generalized here for finite strain kinematics with monotonous hyperelastic stress–strain functions in order to account for large transformation strains that can reach up to 15%.

A major theoretical and numerical difficulty herein is the convexification of the finite deformation phase transformation (PT) problems for multiple phase variants, n⩾2. A lower bound of the mixing energy is provided by the Reuss bound in case of linear kinematics and an arbitrary number of variants, shown by Govindjee et al. (J. Mech. Phys. Solids 2003; 51(4):I–XXVI). In case of finite strains, a generalized representation of free energy of mixing is introduced for a quasi‐Reuss bound, which in general holds for n⩽2.

Numerical validation of the used micro–macro material model is presented by comparing verified numerical results with the experimental data for Cu82Al14Ni4 monocrystals for quasiplastic PT, provided by Xiangyang et al. (J. Mech. Phys. Solids 2000; 48:2163–2182). The zigzag‐type experimental stress–strain curve within PT at loading, called ‘yield tooth’, is approximated within the finite element analysis by a smoothly decreasing and then increasing axial stress which could not be achieved with linearized kinematics yielding a constant axial stress during PT. Copyright © 2007 John Wiley & Sons, Ltd.
Coupling electrical and mechanical effects in discrete element simulations
Authors: Renouf M. , Fillot N.
Published: August 2007

When investigating the electrical characteristics of granular assemblies under dynamical solicitations (powder, steel bead assemblies, etc.), it is difficult to distinguish between effects that are purely electrical and those that are strongly dependent on mechanical effects. Although numerous experimental works have permitted better understanding of the static electrical behaviour of such media, it is difficult to determine the effects control the multi‐physical behaviour of the medium, especially under dynamical solicitations.

In the present paper, numerical investigations of the electrical characteristics of granular material are proposed. Moreover, it presents the formulation of a new model, embedded in the general scheme of discrete element methods, that couples electrical and mechanical effects and takes into account the oxidation phenomenon. Numerical simulations on the basis of experimental works are performed to
validate the model, and the results of dynamical simulations are discussed. Copyright © 2007 John Wiley & Sons, Ltd.
From patronage politics to community deliberation: the recent experience of democratic school management in Brazil
Authors: Borges André
Published: August 2007

The article discusses the limits and possibilities of school empowerment within education systems plagued by pervasive patronage politics. The analysis focuses on reform initiatives implemented by Brazilian sub‐national governments throughout the 1980s and 1990s to allow for the election of school principals by parents, teachers and students. Until the implementation of this reform, state and local authorities had relied on the school system as a source of patronage resources, and principals were nominated according to political criteria. The new system of democratic school management was expected to undermine this patronage‐based system and foster community participation in school decisions. The article relies on secondary evidence to assess the impact of school elections in what concerns the participation of parents, students and teachers in school affairs and the relationship between schools, party politicians and education administrators. It concludes that high levels of social inequality and the lack of a universalistic and effective system of welfare provision constitute serious obstacles to the empowerment of disadvantaged groups in developing societies such as Brazil. On the other hand, the article argues that school empowerment has the potential to undermine resilient patronage structures, by introducing universalistic mechanisms of decision‐making and making school administrators more accountable to their constituencies. Copyright © 2007 John Wiley & Sons, Ltd.
A comparison of pioglitazone and rosiglitazone for hospitalization for acute myocardial infarction in type 2 diabetes
Authors: Gerrits Charles M. , Bhattacharya Mondira , Manthena Shivaji , Baran Robert , Perez Alfonso , Kupfer Stuart
Published: August 2007

Background

Recent studies have raised concerns about potential increased cardiovascular (CV) risk in type 2 diabetes patients treated with some peroxisome proliferator‐activated receptor gamma (PPAR‐gamma) agonists.

Objective

To ascertain the risk of hospitalization for acute myocardial infarction (AMI) in type 2 diabetes patients treated with pioglitazone relative to rosiglitazone.

Methodology

Using data covering 2003–2006 from a large health care insurer in the US, a retrospective cohort study was conducted in patients who initiated treatment with pioglitazone or rosiglitazone. The hazard ratio (HR) of incident hospitalization for AMI after initiation of treatment with these drugs was estimated from multivariate Cox's proportional hazards survival analysis; similarly, the HR was ascertained for hospitalization for the composite endpoint of AMI or coronary revascularization (CR).

Results

A total of 29 911 eligible patients were identified in the database; 14 807 in the pioglitazone and 15 104 in the rosiglitazone group. Baseline demographics, medical history, and dispensed medications were generally well balanced between groups. The unadjusted HR for hospitalization for AMI was 0.82, 95%CI: 0.67–1.01. After adjustment for baseline covariates the HR was 0.78, 95%CI: 0.63–0.96. The adjusted HR for the composite of AMI or CR was 0.85, 95%CI: 0.75–0.98.

Conclusion

This retrospective cohort study showed that pioglitazone, in comparison with rosiglitazone, is associated with a 22% relative risk reduction of hospitalization for AMI in patients with type 2 diabetes. Copyright © 2007 John Wiley & Sons, Ltd.
Synthesis and proton conductivity of poly(styrene sulfonic acid)/heterocycle‐based membranes
Authors: Göktepe Fadime , Bozkurt Ayhan , Günday Şeyda T
Published: August 2007

BACKGROUND: High proton conduction through anhydrous polymer electrolyte membranes is crucial for the application to chemical energy conversion devices such as fuel cells. In this context, novel proton conductors were produced by doping poly(styrene sulfonic acid) (PSSA) with 1H‐1,2,4‐triazole (Tri) and 1.12‐diimidazol‐2‐yl‐2,5,8,11‐tetraoxadodecane (imi3), and their physicochemical properties were investigated.

RESULTS: Different polymer electrolyte membranes were produced by doping of PSSA with Tri and imi3. PSSATrix and PSSAimi3x electrolytes were obtained where x is the doping ratio describing moles of Tri or imi3 per mole of SO3H unit. The membranes demonstrated adequate thermal stability at least up to 200 °C and the dopants acted as plasticizers shifting the Tg values to lower temperatures. PSSATri1 has a maximum proton conductivity of 0.016 S cm−1 at 150 °C and the proton conductivity of PSSAimi30.5 is approximately 10−4 S cm−1 at room temperature.

CONCLUSIONS: Transparent, homogeneous and freestanding films of PSSATrix and PSSAimi3x were produced. It was demonstrated that both Tri and imi3 are efficient proton solvents in PSSA host matrix, and they yielded promising defect‐type conductivities compared to benzimidazole. Tri‐doped membranes clearly showed better conductivity performance at higher temperatures (T > 100 °C). Both PSSATrix and PSSAimi3x polymer electrolytes can be suggested for fuel cell applications. Copyright © 2007 Society of Chemical Industry
Polyamide–silica nanocomposites: mechanical, morphological and thermomechanical investigations
Authors: Sarwar Muhammad Ilyas , Zulfiqar Sonia , Ahmad Zahoor
Published: August 2007

BACKGROUND: The physical properties of polyamides can be enhanced through incorporation of inorganic micro‐ and nanofillers such as silica nanoparticles. Transparent sol‐gel‐derived organic‐inorganic nanocomposites were successfully prepared by in situ incorporation of a silica network into poly(trimethylhexamethylene terephthalamide) using diethylamine as catalyst. Thin films containing various proportions of inorganic network obtained by evaporating the solvent were characterized using mechanical, dynamic mechanical thermal and morphological analyses.

RESULTS: Tensile measurements indicate that modulus as well as stress at yield and at break point improved while elongation at break and toughness decreased for the hybrid materials. The maximum value of stress at yield point (72 MPa) was observed with 10 wt% silica while the maximum stress at break point increased up to 66 MPa with 20 wt% silica relative to that of pure polyamide (44 MPa). Tensile modulus was found to increase up to 2.59 GPa with 10 wt% silica in the matrix. The glass transition temperature and the storage moduli increased with increasing silica content. The maximum increase in the Tg value (144 °C) was observed with 20 wt% silica. Scanning electron microscopy investigation gave the distribution of silica, with an average particle size ranging from 3 to 24 nm.

CONCLUSION: These results demonstrate that nanocomposites with high mechanical strength can be prepared through a sol‐gel process. The increase in the Tg values suggests better cohesion between the two phases, and the morphological results describe a uniform dispersion of silica particles in the polymer matrix at the nanoscale. Copyright © 2007 Society of Chemical Industry
Facile synthesis and characterization of hyperbranched poly(ether amide)s generated from Michael addition polymerization of in situ created AB2 monomers
Authors: Lin Ying , Dong Zhong‐Ming , Liu Xiao‐Hui , Li Yue‐Sheng
Published: August 2007

A new straightforward strategy for synthesis of novel hyperbranched poly (ether amide)s from readily available monomers has been developed. By optimizing the reaction conditions, the AB2‐type monomers were formed dominantly during the initial reaction stage. Without any purification, the AB2 intermediate was subjected to further polymerization in the presence (or absence) of an initiator, to prepare the hyperbranched polymer‐bearing multihydroxyl end‐groups. The influence of monomer, initiator, and solvent on polymerization and the molecular weight (MW) of the resultant polymers was studied thoroughly. The MALDI–TOF MS of the polymers indicated that the polymerization proceeded in the proposed way. Analyses of 1H NMR and 13C NMR spectra revealed the branched structures of the polymers obtained. These polymers exhibit high‐moderate MWs and broad MW distributions determined by gel permeation chromatography (GPC) in combination with triple detectors, including refractive index, light scattering, and viscosity detectors. In addition, the examination of the solution behavior of these polymers showed that the values of intrinsic viscosity [η] and the Mark–Houwink exponent α were remarkably lower compared with their linear analogs, because of their branched nature. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4309–4321, 2007
Layer‐by‐layer assembly of weak‐strong copolymer polyelectrolytes: A route to morphological control of thin films
Authors: Tjipto Elvira , Quinn John F. , Caruso Frank
Published: August 2007

Multilayer films were assembled from a strong polyelectrolyte (poly(diallyldimethylammonium chloride), PDADMAC) and a copolymer containing both strongly charged styrene sulfonate moieties and weakly charged maleic acid moieties (poly(4‐styrenesulfonic acid‐co‐maleic acid), PSSMA). Growth of PSSMA/PDADMAC multilayers was linear, as characterized by UV‐vis spectroscopy and quartz crystal microgravimetry. The influence of both the pH of the PSSMA adsorption solutions and the ratio of SS:MA in the PSSMA on multilayer properties was investigated. Fourier transform infrared spectroscopy results showed that the ionization of carboxylic acid groups in PSSMA/PDADMAC multilayers did not vary significantly with changes in the PSSMA assembly pH. However, the multilayers showed different thicknesses, surface morphologies, and stability to post‐assembly pH treatment. We also demonstrate that PSSMA/PDADMAC multilayers are significantly more stable than PSSMA/PAH multilayers after post‐assembly pH treatment (i.e. the films remain intact when exposed to pH extremes). In addition, the surface morphology of two films (PSSMA 1:1 assembled at pH 5.8, post‐treated at pH 2 and PSSMA 3:1 assembled at pH 5.8, post‐treated at pH 11) changed significantly when the films were exposed to solutions of different pH and, in the former case, this change in film morphology was reversible. The porous morphology after treatment at pH 2 could be reversed to give a significantly smoother film after subsequent exposure to water for 24 h. Our results demonstrate that by the rational choice of the assembly pH of PSSMA, stable and pH‐responsive films can be obtained via the sequential assembly of PSSMA and PDADMAC. These films have potential in controlled release applications where film stability and pH‐responsive behavior are essential. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4341‐4351, 2007
Synthesis and properties of wholly aromatic polymers bearing cardo fluorene moieties
Authors: Liou Guey‐Sheng , Yen Hung‐Ju , Su Yi‐Ting , Lin Hung‐Yi
Published: August 2007

Three series of aromatic polyamides, polyesters, and poly(1,3,4‐oxadiazole)s containing bulky fluorene structures were prepared from 9,9‐bis(4‐carboxyphenyl) fluorene. All of the polymers were readily soluble in many organic solvents and showed useful thermal stability associated with high glass‐transition temperatures in the range of 220–366 °C. These wholly aromatic polymer films were colorless, with high optical transparency, and exhibited UV‐vis absorption bands at 266–348 nm and photoluminescence maximum bands at 368–457 nm within the purple to green region in N,N‐dimethylacetamide (DMAc) solutions. The poly(amine‐amide) Ic exhibited excellent electrochromic contrast and coloration efficiency, changing color from the colorless neutral form to green and then to the dark blue oxidized forms with good stability of electrochromic characteristics. Almost all of these wholly aromatic polymer films were colorless and showed high optical transparency. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4352–4363, 2007
Dual mode model for mixed gas permeation of CO2, H2, and N2 through a dry chitosan membrane
Authors: El‐Azzami Louei A. , Grulke Eric A.
Published: August 2007

Dry chitosan is an excellent candidate for facilitated transport membranes that can be utilized in industrial applications, such as fuel cell operations and other purification processes. This article is the first to report temperature effects on transport properties of CO2, H2, and N2 in a gas mixture typical of such applications. At a feed pressure of 1.5 atm, CO2 permeabilities increased (0.381–26.1 barrers) at temperatures of 20–150 °C with decreasing CO2/N2 (19.7–4.55) and CO2/H2 (3.14–1.71) separation factors. The pressure effect on solubilities and permeabilities were fitted to the extended dual mode model and its corresponding mixed gas permeation model. The dual mode and transport parameters, the sorption heats and the activation energies of Henry's and Langmuir's regimes and their pre‐exponential parameters were determined. The Langmuir's capacity constants were utilized to estimate chitosan's glass transition temperature (CO2: 172 °C, N2: 175 °C, and H2: 171 °C). The activation energies of diffusion in the Henry's law and Langmuir regimes were dependent on the collision diameter of the gases. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2620–2631, 2007
Fractionation and characterization of a protein–polysaccharide complex from Pleurotus tuberregium sclerotia
Authors: Tao Yongzhen , Yan Fan , Zhang Lina
Published: August 2007

A water‐soluble sample (TM4b), extracted from sclerotia of Pleurotus tuberregium, was analyzed using elemental analysis, one‐ and two‐dimensional 1H and 13C NMR. The results indicated that TM4b was protein–polysaccharide complex, and the polysaccharide moiety was hyperbranched β‐D‐glucan with residuals branched at C3, C2, C4, and C6 positions. A preparative size‐exclusion chromatography (SEC) column combined with nonsolvent addition method was used to fractionate TM4b, and nine fractions were obtained. Solution properties of TM4b in 0.15 M aqueous NaCl were studied using static laser light scattering and viscometry at 25 °C. The dependences of intrinsic viscosity ([η]) and radius of gyration (〈S2〉) on weight–average molecular weight (Mw) for TM4b in the Mw range from 1.89 × 104 to 2.58 × 106 were found to be [η] = 0.21M and 〈S2〉 = 3.63M. It indicated that TM4b existed as compact sphere conformation in the aqueous solution. Atomic force microscopy image further confirmed that the TM4b molecules exhibited globular shape in the solution. This work gave valuable information on fractionation and chain conformation characterization of the globular protein–polysaccharide complex. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2546–2554, 2007
Microrheological studies of regenerated silk fibroin solution by video microscopy
Authors: A. Raghu , R. Somashekar , Ananthamurthy Sharath
Published: August 2007

We have carried out studies on the rheological properties of regenerated silk fibroin (RSF) solution using video microscopy. The degummed silk from the Bombyx mori silkworm was used to prepare RSF solution by dissolving it in calcium nitrate tetrahydrate‐methanol solvent. Measurements were carried out by tracking the position of an embedded micron‐sized polystyrene bead within the RSF solution through video imaging. The time dependent mean squared displacement (MSD) of the bead in solution and hence the complex shear modulus of this solution was calculated from the bead's position information. We present here the results of rheological measurements of the silk polymer network in solution over a frequency range, whose upper limit is the frame capture rate of our camera at full resolution. By examining the distribution of MSD of beads at different locations within the sample volume, we demonstrate that this probe technique enables us to detect local inhomogeneities at nanometre length scales, not detectable either by a rheometer or from diffusing wave spectroscopy. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2555–2562, 2007
Influence of the draw ratio on the tensile and fracture behavior of NMMO regenerated silk fibers
Authors: Corsini Paola , Perez‐Rigueiro José , Guinea Gustavo V. , Plaza Gustavo R. , Elices Manuel , Marsano Enrico , Carnasciali Maria M. , Freddi Giuliano
Published: August 2007

The tensile properties and fracture surfaces of N‐methylmorpholine‐N‐oxide (NMMO) regenerated silk fibroin fibers produced with a range of draw ratios has been characterized and related to their microstructure with data obtained from Raman spectroscopy and birefringence measurements. The spinning process allows control of two different draw ratios, coagulation, and postspinning, and it has been found that the microstructure and the properties of the fibers can be modified by the proper combination of both draw ratios. NMMO regenerated silk fibroin fibers subjected to postspinning drawing yield tensile properties comparable to other regenerated fibers and strain at breaking comparable to natural Bombyx mori silk fibers. Tensile strength; however, is still significantly lower than that of natural fibers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2568–2579, 2007
Nonlinear rheological behavior of silica filled solution‐polymerized styrene butadiene rubber
Authors: Sun Jin , Song Yihu , Zheng Qiang , Tan Hong , Yu Jie , Li Hong
Published: August 2007

The reinforcement and nonlinear viscoelastic behavior have been investigated for silica (SiO2) filled solution‐polymerized styrene butadiene rubber (SSBR). Experimental results reveal that the nonlinear viscoelastic behavior of the filled rubber is similar to that of unfilled SSBR, which is inconsistent with the general concept that this characteristic comes from the breakdown and reformation of the filler network. It is interesting that the curves of either dynamic storage modulus (G′) or loss tangent (tan δ) versus strain amplitude (γ) for the filled rubber can be superposed, respectively, on those for the unfilled one, suggesting that the primary mechanism for the Payne effect is mainly involved in the nature of the entanglement network in rubbery matrix. It is believed there exists a cooperation between the breakdown and reformation of the filler network and the molecular disentanglement, resulting in enhancing the Payne effect and improving the mechanical hysteresis at high strain amplitudes. Moreover, the vertical and the horizontal shift factors for constructing the master curves could be well understood on the basis of the reinforcement factor f(φ) and the strain amplification factor A(φ), respectively. The surface modification of SiO2 causes a decrease in f(φ), which is ascribed to weakeness of the filler–filler interaction and improvement of the filler dispersion. However, the surface nature of SiO2 hardly affects A(φ). © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2594‐2602, 2007
Cross‐correlation patterns of air and soil temperatures, rainfall and Diaprepes abbreviatus root weevil in citrus
Authors: Li Hong , Futch Stephen H , Syvertsen James P
Published: August 2007

Time series cross‐correlation analysis is appropriate when measuring relationships between two different time series. Using this approach, the authors quantified the relationship between the time series air temperature (AT), soil temperature (ST), rainfall, relative humidity (RH) and Diaprepes abbreviatus (L.) (Coleoptera: Curculionidae) root weevil across a period of 30 months, and examined how closely the distribution of Diaprepes root weevil was related to AT, ST, rainfall and RH within this period of time. The study was conducted on a poorly drained Spodosol in a citrus [Citrus sinensis (L.) Osb.] grove in DeSoto County, south‐west Florida, from April 2001 to September 2003. Adult weevil populations were monitored using 100 Tedders traps in a 30 × 15 m grid. Weather data (0.6 m AT, 0.1 m ST, 2 m rainfall and 2 m RH) were monitored by Florida Automated Weather Networks. The monthly mean and standard deviation were 22.3 ± 4.0 °C for AT, 24.7 ± 4.2 °C for ST, 146.0 ± 122.7 mm for rainfall, 78.2 ± 4.7% for RH and 0.74 ± 0.59 adults trap−1 for the root weevil. Weevil density was positively correlated with AT (r = 0.45, P < 0.0133), ST (r = 0.49, P < 0.0067) and rainfall (r = 0.38, P < 0.0450). The environmental variables AT, ST, rainfall and RH were correlated with each other (0.42 < r < 0.99, 0.0246 < P < 0.0001). All weather and Diaprepes variables were autocorrelated with each other within a time of 3 months. The cross‐correlation coefficients varied between − 0.59 and 0.65 for the pair‐variable between Diaprepes, AT, ST and rainfall, and these pair‐variables were correlated across a time period of 4 months. The present results suggested that warm, wet conditions contributed to the root weevil outbreaks, and environmental temperature and rainfall were the variables most closely related to Diaprepes root weevil distribution in time. Copyright © 2007 Society of Chemical Industry
Facilitating meta‐analyses by deriving relative effect and precision estimates for alternative comparisons from a set of estimates presented by exposure level or disease category
Authors: Hamling Jan , Lee Peter , Weitkunat Rolf , Ambühl Mathias
Published: August 2007

Epidemiological studies relating a particular exposure to a specified disease may present their results in a variety of ways. Often, results are presented as estimated odds ratios (or relative risks) and confidence intervals (CIs) for a number of categories of exposure, for example, by duration or level of exposure, compared with a single reference category, often the unexposed. For systematic literature review, and particularly meta‐analysis, estimates for an alternative comparison of the categories, such as any exposure versus none, may be required. Obtaining these alternative comparisons is not straightforward, as the initial set of estimates is correlated. This paper describes a method for estimating these alternative comparisons based on the ideas
originally put forward by Greenland and Longnecker, and provides implementations of the method, developed using Microsoft Excel and SAS. Examples of the method based on studies of smoking and cancer are given. The method also deals with results given by categories of disease (such as histological types of a cancer). The method allows the use of a more consistent comparison when summarizing published evidence, thus potentially improving the reliability of a meta‐analysis. Copyright © 2007 John Wiley & Sons, Ltd.
Model selection in logistic joinpoint regression with applications to analyzing cohort mortality patterns
Authors: Czajkowski Michal , Gill Ryan , Rempala Grzegorz
Published: August 2007

We consider a general model for anomaly detection in a longitudinal cohort mortality pattern based on logistic joinpoint regression with unknown joinpoints. We discuss backward and forward sequential procedures for selecting both the locations and the number of joinpoints. Estimation of the model parameters and the selection algorithms are illustrated with longitudinal data on cancer mortality in a cohort of chemical workers. Copyright © 2007 John Wiley & Sons, Ltd.
A new generation of getter‐coated sputter ion pumps for XHV applications
Authors: Mura M. , Paolini C.
Published: August 2007

A new concept of sputtered ion getter pump is presented. The body of this pump is internally coated by a getter thin film constituted by a layer of TiZrV together with a protective covering of palladium, according to a technology that CERN (European Center for Nuclear Research) licensed us.

TiZrV is a well‐known alloy able to pump getterable gases such as hydrogen, oxygen, nitrogen, carbon monoxide and dioxide. With the exception of H2, the sorption of these gases is not reversible and it causes a progressive contamination of the bulk of the material. With the addition of the palladium overlayer, the pumping action is limited to hydrogen and carbon monoxide, but the lifetime of the film is strongly enhanced, thanks to the possibility of an unlimited number of thermal activations, which restore the initial performances of the film.

An innovative sputter ion pump design, optimized for both pumping speed in ultra high vacuum and getter film sputtering, will be introduced. Moreover, pumping speed measurements and ultimate pressure data, obtained after a relatively short bake‐out at temperature lower than standard procedures, will be reported.
Plasma investigation of PVD processes operating in dc continuous and/or dc pulsed mode
Authors: Strauss Georg N. , Schlichtherle Stefan , Pulker Hans K.
Published: August 2007

The plasma of different dc and dc pulsed pvd processes (TiN and Ta2O5 magnetron sputtering, Ta2O5 ion plating) has been investigated by means of a mass spectrometric plasma monitoring system PPM421 (Inficon). The ion energy distribution of the process relevant positive ions has been measured and the dependence of the plasma properties on the process parameters like pulse frequency and pulse voltage was analysed. Starting with an overview concerning a theoretical concept behind the plasma properties in dc pulsed sputter processes, theoretical predictions from this theory about the kinetic energy of the ions and the shape of the ion energy distribution are compared with the experimental results in different dc pulsed sputter processes. A significant difference can be seen in level and distribution of the ion energy in conventional dc magnetron processes compared to dc pulsed processes. The process parameters pulse frequency and pulse voltage control the kinetic energy of the process ions. The theoretically predicted properties of a pulsed plasma could experimentally be confirmed.
Preparation of glycerides by controlled esterification
Authors: Feuge R. O. , Willich R. K. , Guice W. A.
Published: August 2007

A simple procedure for esterifying glycerides without interesterification occurring would be highly useful for preparing on a large scale a number of tailor‐made fats, including cocoa butter‐like fats. Such esterifications were carried out by employingp‐toluenesulfonic acid as catalyst and continuously removing the water of esterification by azeotropic distillation with aliphatic hydrocarbons or by stripping with vaporized hydrocarbons. Even thoughp‐toluenesulfonic acid rapidly disproportionated 1‐monostearin, even at 120C, apparently esterification was faster and only a moeerate amoung of ester‐ester interchange and acidolysis occurred. Diacid glycerides might be prepared from monoglycerides by the procedure which was employed. Saturated diglycerides were esterified with oleic acid with little ester‐ester interchange or acidolysis occurring; however, intraesterification was extensive. The reaction between 1,3‐distearin and oleic acid yielded approximately 75% 1‐oleodistearin and 25% 2‐oleodistearin. Saturated diglycerides were esterified with sebacic acid, again with little or no interesterification occurring.
Three new oilseeds rich incis‐11‐eicosenoic acid
Authors: Mikolajczak K. L. , Smith C. R. , Wolff I. A.
Published: August 2007

Marshallia cacspitosa Nutt. seed oil (family Compositae) contains 44%cis‐11‐eicosenoic acid, and is the first oil from the Compositae found to contain a high proportion of C20‐monoenoic acid. Seed oils ofAlyssum maritimum (L.) Lam. and ofSelenia grandis Martin (family Cruciferae) contain 42 and 58% of the same acid, respectively.

The C20 acids from all three oils were obtained in nearly pure form by fractional distillation of the mixed methyl esters by means of a spinning band column. Permanganate‐periodate oxidation of the purified methyl esters yielded predominantly nonanoic and undecanedioic acids.
The impact of biodegradable surfactants on water quality
Authors: Brenner Theodore E.
Published: August 2007

The purpose of this paper is to review some of the recent contributions of the detergent industry to the national effort for cleaner water. Probably the single most important achievement to date has been the industry’s voluntary conversion from the use of alkyl benzene sulfonate (ABS) to linear alkylate sulfonate (LAS) and other biodegradable surfactants. This changeover was completed in mid‐1965 at a cost that has been estimated to exceed $150,000,000.

Since LAS was the surfactant of primary interest, the bulk of the pre‐ and postconversion research, in terms of water‐pollution control, has been with that material. This paper concerns itself mainly with the over‐all impact of the conversion to LAS on water quality. Data from pilot and full‐scale sewage‐treatment plants throughout the country are included, which clearly demonstrate the effectiveness of the conversion in terms of significantly lower surfactant residue levels.
Autoxidation of fatty materials in emulsion. III. Application of GLC and TLC to studies of the histidine‐catalyzed autoxidation of methyl oleate
Authors: Hampson J. W. , Herb S. F. , Magidman P.
Published: August 2007

Methyl oleate, emulsified with sodium dodecyl‐sulfate, was extensively oxidized, and the amount of oleate which was reacted was determined by GLC using methyl palmitate as an internal standard. The effects of histidine, iron, and histidine plus iron were compare with the uncatalyzed reaction in the presence and absence of ultraviolet light. Results in the absence of ultraviolet light confirmed previous findings that histidine and histidine plus iron are prooxidants at the concentration studied. In the presence of ultraviolet light the rate of oleate oxidation was about 100× faster than that of the nonirradiated reaction, and the effect of the catalysts was almost negligible. The principal products, determined by GLC and TLC, were epoxide and α,β‐unsaturated carbonyl. Hydroperoxy, hydroxy, acid and aldehyde compounds were also present. Epoxy stearate, determined by GLC, compared favorably with epoxy stearate as determined by use of the Durbetaki method.
Isolation of two isomeric 2, 6‐nonadienals and two isomeric 4‐heptenals from beef and mutton tallow
Authors: Hoffmann G. , Meijboom P. W.
Published: August 2007

By the use of mainly chromatographic and UV spectrophotometric techniques, 4cis‐ and 4trans‐heptenal (with a “green” odor, characterized in high dilution as tallowy, creamy, butterscotch‐like) and 2trans,6cis‐ and 2trans,6trans‐nonadienal (with a “green”‐cucumber‐like and a tallowy odor) were isolated from reverted beef and mutton tallow.
Hydrogenation: principles and catalysts
Authors: Allen R. R.
Published: August 2007

The hydrogenation reaction is the most important chemical reaction in the fat and oil industry. It is also perhaps the least understood.

The most critical factor in the reaction is the catalyst. Several different types of metal catalysts can be used. The reaction conditions as well as other factors determine the type of product produced. However, all the factors can be related to effects on the catalyst.

The “selectivity” concept of catalyst evaluation is not new. However, the term has come to have several different meanings. It is believed the term should be used only for chemical selectivity which can be easily determined. The “selectivity ratio” number is very useful and can be used to judge the performance of a catalyst.
Polymorphism of saturated triglycerides: II. 1,3‐dipalmito triglycerides
Authors: Gray M. S. , Lovegren N. V.
Published: August 2007

Differential scanning calorimetry was used to examine triglycerides of the 16‐N‐16 series, whereN is an even‐carbon, saturated fatty acid of 2 to 18 carbons in length. The procedures used to obtain heats of fusion and crystallization of the various triglycerides and their polymorphs are described. Small samples (ca. 1‐2 mg) were used to investigate polymorphs with relatively rapid rats of conversion, but more accurate calorimetric data were obtained with larger samples. Capillary melting points were also obtained for the various triglycerides and their polymorphs. Calorimetric and melting point data are given.
Trace metal content of a herring oil at various stages of pilot‐plant refining and partial hydrogenation
Authors: Elson C. M. , Ackman R. G.
Published: August 2007

Samples of a typical Atlantic herring oil at various stages of pilot‐plant processing were analyzed for cadmium, selenium, arsenic, mercury, copper, lead, and zinc. The FAO/WHO Codex Alimentarius requirements for low levels of specific metals in edible oils were always difficult to meet completely in either a washed and bleached oil or in two lots of oil processed from one crude oil by the additional steps of partial hydrogenation and deodorization. The mercury content of the crude oil was relatively low and was not greatly affected by processing. The selenium level of 47 ppb in the crude oil was significantly lowered by hydrogenation and deodorization. Arsenic was removed by alkali refining. The lead content was reduced by only 40% upon refining, probably because lead was present as an organometallic material. The concentration of the other heavy elements was generally lowered during processing.
The palm oil situation
Authors: Doak Thomas E.
Published: August 2007

In broad perspective, total world demand for oils is growing rapidly, and palm oil will be seen in future years as a welcome addition to total world supply. It also seems clear that palm oil utilization is broadening at a faster rate than production is increasing. It appears this utilization is growing fastest in the “new markets” of Asia, the Mid‐East and Latin America, rather than in the “old markets” of Europe and the United States.
1978 world fats and oils situation
Authors: Holz Alan E.
Published: August 2007

As expected, world oil and meal production and demand this year have been above trend, but the U.S. share of world markets has been greater than projected because of smaller than anticipated oilseed crops in Brazil, the Soviet Union, India, and Senegal. World 1978 fats and oils supplies should be around 53 million metric tons with export markets absorbing about 17 million metric tons. The U.S. 1978 soybean crop may equal or excel the 1977 crop; Canada's oilseed crops are expected to be up, and Brazil's 1979 soybean crop is expected to rebound from the 1978 level.
Manufactured hard butters
Authors: Marcus J. G. , Puri P. S.
Published: August 2007

The physical characteristics of various commercial hard butters are compared by determining their solid contents (dilatometrically) and melting thermograms (DSC). For most applications in the confectionery industry, hard butters manufactured by the hydrogenation and interesterification of fats and oils offer economic advantages over those obtained by the fractionation of fats.
Chemometrics in food research: Relationships between triglyceride groups and fatty acid composition in olive oil
Authors: Damiani P. , Burini G. , Daddi P.
Published: August 2007

The values (mol %) of the triglyceride Gnu groups, each containing all the molecular species with the same carbon numer and unsaturation, are different for various oils; in this paper, their use for analytical purposes is therefore hypothesized. To this end, the values (mol %) of Gnu groups—with respective means, standard deviations and coefficients of variation‐were first of all established using the l, 3‐random‐2‐random distribution hypothesis on 50 olive oil samples; with these values, along with the relative data of the fatty acid composition, a computer study was carried out to obtain some regression models of use for estimating the Gnu values (mol %) of other olive oil samples. The evaluation of the regression models procedure (RMP) was carried out comparing the values obtained by such a method for 6 other commercial olive oils with those experimentally determined by Ag+‐TLC coupled with direct triglyceride GLC analysis. Moreover, these models were tested with the data of fatty acid composition of 4 different seed oils, providing often negative Gnu values, always different, however, from those of olive oil.
Synthesis and properties of Mono‐, Di‐ and trienoic fatty esters containing a 12,13 double bond
Authors: Rakoff H. , Emken E. A.
Published: August 2007

Methyl trans‐12‐octadecenoate‐9, 10‐d2 was obtained from methyl threo‐12, 13‐dihydroxy‐cis‐9‐octadecenoate by a sequence of reactions involving formation of an ethoxydioxolane, catalytic deuteration of the double bond, and conversion of the ethoxydioxolane group to an ethylenic bond. Methyl cis‐ and trans‐12‐octadecenoate‐15, 15, 16, 16‐d4 and methyl cis‐ and trans‐12‐octadecenoate‐9, 10, 15, 15, 16, 16‐d6 were obtained from the Wittig coupling of hexyl‐3, 3, 4, 4‐d4‐triphenylphosphonium bromide with methyl 12‐oxododecanoate and methyl 12‐oxododecanoate‐9, 10‐d2, respectively. The four geometrically isomeric methyl 12, 15‐octadecadienoates‐9, 10‐d2 were prepared by the Wittig reaction between cis‐ or trans‐3‐hexenyltriphenylphosphonium bromide and methyl 12‐oxododecanoate‐9,‐10‐d2 with butyl lithium in ethyl ether. The Wittig reaction between hexyl‐3, 3, 4, 4‐d4 ‐triphenylphosphonium bromide and methyl 12‐oxo‐cis‐ or trans‐9‐dodecenoate was used to prepare the four geometric isomers of methyl 9, 12‐octadecadienoate‐15, 15, 16, 16‐d4, whereas the same reaction between eis‐ or trans‐3‐hexenyltriphenyl‐phosphonium bromide and methyl 12‐oxo‐cis‐ or trans‐9‐dodecenoate afforded the eight geometrically isomeric methyl 9, 12, 15‐octadecatrienoates. In each case, the stereochemistry of the double bond formed in the Wittig reaction was controlled by choice of reaction conditions. Pairs of isomers formed during each synthesis were separated by partial silver resin chromatography. Physical constants presented include13C nuclear magnetic resonance chemical shifts, melting points, equivalent chain lengths and percentage trans by infrared spectroscopy.
Vapor‐Phase hydrogenation of methyl linoleate in the presence of a supported copper catalyst
Authors: Lidefelt J. ‐O. , Magnusson J. , Schöön N. ‐H.
Published: August 2007

Methyl linoleate was hydrogenated in the vapor phase in the presence of a copper‐on‐alpha alumina catalyst. The kinetics of the reaction could be formulated with a Eley‐Rideal mechanism including the reaction between chemisorbed methyl ester and hydrogen in the gas phase. The absorption coefficients in the rate equation were based on separately performed adsorption studies recently reported.
Vapor‐Phase hydrogenation of methyl oleate in the presence of a supported nickel catalyst
Authors: Lidefelt J.‐ O. , Magnussoim J. , Schöön N.‐ H.
Published: August 2007

The reaction order with respect‐to hydrogen was found to be higher than unity and increased with increasing temperature in the vapor‐phase hydrogenation of methyl oleate in the presence of a supported nickel catalyst. These findings may be of certain interest in understanding the role that hydrogen plays in fat hydrogenation selectivity. Two reaction mechanisms were discussed to explain the high reaction order. The two reaction models were shown to give the same rate equation.
The role of hydrogen in the selectivity of vapor‐Phase hydrogenation of methyl linoleate
Authors: Lidefelt J.‐ O. , Magnusson J. , Schöön N.‐ H.
Published: August 2007

Methyl linoleate was hydrogenated in the vapor phase in the presence of a nickel on alpha‐alumina catalyst. A reaction mechanism was proposed to explain the fact that the selectivity is influenced by the hydrogen pressure. A rate equation was derived based on the mechanism and the rate constant was evaluated from kinetic experiments. The adsorption coefficients in the rate equation were based on separately performed adsorption studies recently published.
Optimization of an industrial chemical cleaning process for glass lenses
Authors: Zoller U.
Published: August 2007

The chemical cleaning of glass constitutes an extremely complicated problem, since its exposure to chemical attack by either water, acid, alkali salt solutions or even gases in the atmosphere may result in corrosion. In reality, corrosion generally occurs in a combination of ways simultaneously. This is particularly true with respect to industrial chemical cleaning of glass lenses, in which the absolute cleanliness (and spotlessness) of the surface of the lenses is the primary condition for further processing and/or fitness to the ultimate use. This paper presents data of a selected industrial field study (in vivo conditions) in which an application, optimization, and assessment of the chemical cleaning process (and its results) of glass lenses involving various surfactant‐based formulations has been carried out. With a high level content of polyphosphates (i.e., sodium tripolyphosphates), the phosphate ester‐based formulations were found to perform better than formulations based on other classes of surfactants (i.e., anionics and nonionics). The best results were achieved with 2.5–3.5% solutions of the formulation that contained ca. 3% of surface active agent. The optimal ratio of alkali‐phosphate in the formulations was found to be in the range of 1:1.7–1:2.4. The results are discussed and conclusions with regard to the “real world” of such industrial processes have been drawn.
A rapid gas chromatographic method for the determination of BHA and BHT in vegetable oils
Authors: Hartman Kenneth T. , Rose Lucien C.
Published: August 2007

A gas liquid chromatographic (GLC) technique has been developed which requires about 20 min for the determination of BHA and BHT in vegetable oils. This method involves the addition of an internal standard to a weighed portion of the oil, dilution of the mixture with carbon disulfide, and injection into the Gas Chromatograph. BHA and BHT are isolated from the nonvolatile vegetable oil by using a short precolumn located in the sample port block of the gas chromatograph. Up to 35 consecutive sample injections per day have been made on the same precolumn with no appreciable effect on the accuracy of the determination. The precolumn is cleaned at the end of each day’s operation. The clean precolumn is allowed to equilibrate to sample port block temperature overnight for the following day’s analysis. Identification of BHA and BHT can be confirmed with a second GLC column which reverses the elution order of these compounds. Soybean, cottonseed, corn and peanut oils fortified with 20, 60 and 100 ppm each of BHA and BHT showed a recovery range of 97% to 104%.
Optical activity of butterfat and vegetable oils
Authors: Anderson B. A. , Sutton C. A. , Pallansch M. J.
Published: August 2007

Optical activities of oils freshly expressed from viable seeds of rape, soybean and peanut show no change in rotation with time; neither do oils extracted from these materials by diethyl ether, as previously reported by other workers. Similarly, no evidence for racemization of butterfat isolated immediately after milking could be found. On removal of the steroids present, by chromatography on Celite impregnated with digitonin, and removal of the mono‐ and diglycerides by chromatography on alumina, butterfat maintained the highest degree of optical activity compared to most of the vegetable oils studied. This residual activity of butterfat tends to substantiate preferential location of short chain fatty acids on the 1 or 3 position of the triglycerides.
Calcium phytate: Effect of ph and molar ratio on in vitro solubility
Authors: Grynspan Frida , Cheryan Munir
Published: August 2007

Calcium and phytate phosphorus were highly soluble below pH 4 at all molar ratios of calcium (Ca) to phytic acid (PA) studied (0.512.67). As pH is increased above 4, there is a drop in solubility, the magnitude of which depends on the Ca:PA molar ratio. Above pH 6, the greatest calcium precipitation occurred at molar ratios between 4 and 6.5; both lower and higher Ca:PA molar ratios showed higher calcium solubility. In contrast, phytate phosphorus solubility decreased in proportion to the Ca:PA molar ratio, showing essentially complete precipitation above the Ca:PA ratio of 5. The pentacalcium phytate salt probably predominates when calcium is not limiting. Under calcium‐limiting conditions, the complexes resolubilize as the pH is increased above 7.
HPLC Analysis of cyclopropenoid fatty acids
Authors: Loveland P. M. , Pawlowski N. E. , Libbey L. M. , Bailey G. S. , Nixon J. E.
Published: August 2007

Cyclopropenoid fatty acid methyl esters have been analyzed by high pressure liquid chromatography (HPLC). The refractive index detector's linear response to various lipids was studied. Verification of peak identity was by spectroscopy of collected peaks and cochromatography with authentic samples. The HPLC method is simple, convenient and gives precision and absolute, values which are consistent with those from traditional methods.