Ports and the local embedding of commodity flows

Empirical evidence remains lacking about the territorial embedding of material flows. An analysis of 189 port regions in advanced economic areas (Europe, Japan, and the United States), validates a number of ideas proposed by regional science and transport geography. Core economic regions such as large urban tertiary centres concentrate most valued, diversified, and weighty traffic, while more peripheral and traditional ones tend to specialize in bulky traffic. Moreover, the level of industry relatedness of port traffic appears as a key component of the socio‐economic wealth of port regions. The research also underlines noticeable linkages between types of port regions and types of port‐related policies across the three studied areas.     

Characterization of arsenic species in kidney of the clam Tridacna derasa by multidimensional liquid chromatography-ICPMS and electrospray time-of-flight tandem mass spectrometry

The identification of water-soluble arsenic species in a kidney of the Tridacna clam by electrospray quadrupole/time-of-flight mass spectrometry (ES Q-TOF MS) was investigated. The species were isolated by three-dimensional LC (size exclusion-anion exchange-cation exchange); the elution of arsenic was monitored by ICPMS. The average accuracy and precision of the molecular mass measurements, studied for a number of organoarsenic standards, were 22 (negative bias) and 15 ppm, respectively. Structural information was obtained in the tandem Q-TOF mode. A total of 15 organoarsenic species were identified, and 13 of these possessed the dimethylarsinoyl group (8 ribofuranosides, 4 acyclic compounds, and 1 dihydroxyfuran). Four of these species were previously unreported. Arsenobetaine and dimethylarsinic acid were also detected. The major species (accounting for up to 50% water-soluble arsenic) was 5-dimethylarsinoyl-2,3,4-trihydroxypentanoic acid. The metabolic interrelationships of these compounds and their significance are briefly discussed.     

Ascorbic acid,aroma compounds and browning of orange juices related to PET packaging materials and pH

The ascorbic acid content of orange juice made from concentrate was measured after 9 months of storage at 20 °C in glass, standard monolayer polyethylene terephthalate (PET₁), multilayer PET (PET₂) and plasma‐treated PET (PET₃) containers. Glass enabled the best preservation of ascorbic acid and, in plastic packaging materials, ascorbic acid losses were correlated with their oxygen permeability. PET₂ and PET₃, which exhibit oxygen permeability 10 times less than that of PET₁, enabled a gain of 100 mg L^?1 after 9 months of storage. Freshly hand‐squeezed orange juice samples were adjusted to various pH values using sodium hydroxide; a rise in the pH from 3.2 to 4.0 significantly reduced the amounts of off‐flavours (i.e., furfural and α‐terpineol) appearing during storage, by 79% and 65%, respectively. Moreover, an increase in the pH from 3.2 to 4.0 enabled the protection of ascorbic acid levels without detrimentally increasing non‐enzymatic browning. Copyright © 2006 Society of Chemical Industry     

Effect of pulp reduction and pasteurization on the release of aroma compounds in industrial orange juice

ABSTRACT:  Release of aroma compounds in orange juice according to pulp content and pasteurization was performed by headspace-solid phase microextraction (HS-SPME), HS-SPME-GC-olfactometry, and by the determination of partition coefficients of aroma compounds between the juice and the headspace. Orange juices with 12% and 6% pulp contents were collected from a processing line before and after pasteurization. HS-SPME revealed that the 6% pulp juice was the most affected by pasteurization, with an increase in the release of several aroma compounds that are generated by heat treatment (that is, α- and β-terpinéol) and a decrease in the release of compounds sensitive to pasteurization (that is, neral and geranial). Principal component analysis of olfactometric data allowed discriminating fresh and pasteurized juices, regardless of the pulp content. The determination of the gas/liquid partition coefficients by the phase ratio variation method was possible for 7 aroma compounds. For the most hydrophobic ones, the release of aroma compounds in fresh juices was higher in the 6% pulp juice than in the 12% pulp juice. However, in pasteurized juices, the difference between their partition coefficients was less marked. Potential interactions between cloud proteins and hydrophobic aroma compounds may explain this phenomenon.     

Effect of crystallization on barrier properties of formulated polylactide

Polylactide (PLA), a biodegradable polymer obtained from biomass, was formulated with a nucleating agent, talc, and a plasticizer, acetyl tributyl citrate, and cold crystallized in α and α′ form. The barrier properties of crystallized PLA were investigated as a function of the formulation and the crystalline form, thanks to three molecules with increasing polymer interactions, i.e. helium, oxygen and ethyl acetate (EA). Contrary to expectation, the oxygen diffusion coefficient in neat and formulated PLA did not decrease with crystallization. Even an increase of the diffusion coefficient was noticed for the most interacting probe, EA, in formulated PLA. Conditioning of neat and formulated PLA in an atmosphere containing EA vapour caused a modification of the material structure by plasticization and induced crystallization even at small EA activities. The plasticizing effect caused the glass transition temperature T_g to shift to below ambient temperature. In the case of neat PLA induced crystallization in solely the α form was obtained, and in the case of formulated PLA a blend of α and α′ forms was observed. Copyright © 2011 Society of Chemical Industry     

Time-Dependent Compressive Strength of Unidirectional Viscoelastic Composite Materials

The strength of unidirectional composites is often lower in compressionthan in tension, making compressive strength an especially importantdesign criterion. Compressive strength in the fiber direction depends onthe stiffness of the matrix material, which softens over time due toviscoelastic effects, and thus lowers the strength of the composite.This reduction must be accounted for in assessing the long-termdurability of composite structures.The dependence of compressive strength on time and temperature hasbeen investigated for a unidirectional carbon/epoxy composite material.Experimental results for strength versus time are compared withanalytical predictions based on a one-dimensional fiber microbucklingmodel and numerical results from finite element analysis.     

Barrier properties of poly(lactic acid) and its morphological changes induced by aroma compound sorption

The barrier properties of poly(lactic acid) (PLA) play a key role in food packaging applications. For their optimization, the influence of crystallinity on the barrier properties of PLA and the interaction of PLA with the aroma compound ethyl acetate were investigated. PLA film samples with various crystallinities were fabricated by flat die extrusion and thermocompression and compared to PLA Biophan^?. The degree of crystallinity had no effect on the oxygen permeability. However, an increase of crystallinity caused a decrease in ethyl acetate sorption. The sorption isotherm of ethyl acetate obtained using microgravimetry showed a steep increase with increasing aroma activity, a form which is consistent with a plasticization effect. This behaviour was verified using differential scanning calorimetry and dynamic mechanical analysis. Sorption caused a marked decrease in the glass transition temperature well below room temperature to approximately 0 °C. Furthermore, PLA underwent a solvent‐induced crystallization when equilibrated in ethyl acetate atmosphere at an activity of 0.5. The results obtained show the importance of considering possible interactions between polymer and foodstuff during the optimization step of polymeric materials for food packaging applications. Copyright © 2010 Society of Chemical Industry     

Sorption of aroma compounds in PET and PVC during the storage of a strawberry syrup

The sorption of 14 aroma compounds into PET and PVC was monitored during storage of a strawberry syrup for 1 year. Concentrations in the syrup and in the polymer were determined during storage and compared with previously published results obtained with glass bottles. Apparent partition coefficients between the polymer and the syrup (noted K_app) were estimated from experimental kinetics without reaching equilibrium K_app values and optimally identified from the kinetic data obtained between 30 and 90 days. They exhibited a similar behaviour for both polymers with values were between 2 × 10^-5 and 2 × 10^-3, 4 × 10^-5 and 3 × 10^-2, respectively, for PET and PVC. The variation of K_app values in PET was mainly correlated to the polarity of tested compounds as assessed by their log P values. By contrast, the variations in K_app values for PVC were mainly related to their chain lengths. Due to slightly higher partition coefficients and diffusion coefficients in PVC compared with PET, the amount of absorbed aroma was four times higher in PVC than in PET; however, the amount of absorbed aroma compounds was less than 0.1% of the initial amount present into the syrup, except for octyl butanoate. The variation in concentration in the syrup was interpreted as a combination of a degradation process and a transport process into the packaging material. Both effects were particularly noticeable for both PET and unstable aroma compounds.     

Height-gain study for 23 km links at 9.6, 11.4, and 28.8 GHz

A study of atmospheric-induced fading on 23 km links at 9.6, 11.4, and 28.8 GHz near Boulder, CO, is described. Height-gain observations and refractivity profile measurements were obtained using a 300 m tower as one end of the links. Observations were obtained when the vertical refractive index profile was smooth and when it displayed significant variations in gradient. Narrow beam and wide beam receiving antennas were used for comparison of relative performance during fading. Fading types which result from atmospheric ray bending are listed and characterized. Examples of the different fading types observed, e.g., atmospheric multipath and radio holes, are presented.