Editor's Introduction

This paper reviews the state of the art in processing and extraction of ocean floor manganese nodules. It briefly reviews the mining sites where the abundant rich nodules occur and also discusses the metal distribution in nodules in view of economical processing and extraction of these metal values.

The paper discloses in a detailed manner the physical and chemical characteristics of nodules, including porosity, surface area, water content and the effect of temperature on crystal structure of major constituents of nodules.

In the extraction aspect of nodules, the paper reviews two different extraction schemes revealed in the literature, namely hydrometallurgical treatment and pyrometallurgical treatment. The hydrometallurgical treatments include acid leaching, ammonia leaching, leaching with reducing agents and leaching after high temperature pre-treatments such as in sulfating rousting, while the pyrometallurgical processes include smelting, chlorination-vaporization and segregation. The paper also covers metal recovery processes from leach liquor.

An economic survey of processing nodules has been made in terms of problems associated with metal-marketing, and impact of metal production from nodules on mineral industries.     

Phenotypic and PCR-based characterization of the microflora in Norvegia cheese during ripening

Microbiological sampling of Norvegia cheese from three cheese factories was done during ripening. The evolution of aerobic mesophilic bacteria, lactococci, lactobacilli, enterococci, presumptive leuconostoc and pediococci was investigated after 30, 90, 180 and 270 days of ripening. Isolates (135) of non-starter lactic acid bacteria (NSLAB) from nine Norvegia cheeses after 90, 180 and 270 days of ripening were examined. The isolates were tested by physiological and biochemical assays, species-specific PCR and 16S rDNA sequencing. After 90 days of ripening Leuconostoc spp., most probably from the starter, and the NSLAB specie Lactobacillus paracasei dominated among the isolates, however, after longer ripening Lb. paracasei dominated. The development and evolution of the microflora in Norvegia varied according to dairy and ripening time.     

A sorption rate hypothesis for the increase in H2 permeability of palladium-silver (Pd-Ag) membranes caused by air oxidation

Hydrogen permeation measurements were performed at 300 °C for 25-μm cold-rolled Pd-Ag 25 wt% membranes before and after air oxidation at the same temperature as permeation. The air oxidation resulted in enhanced H₂ permeation through the membrane, as well as a roughening of the surface with the formation of surface grains and defects. The protruding grains can be leveled off by exposure to H₂ but the surface defects cannot. These microstructure changes are only on the membrane surfaces and do not create transmembrane defects that would allow permeation for gas species other than H₂. The H₂ permeability of the oxidized membrane increased by 25-90% compared to that of the as-received film at the same permeation condition, and the membranes retained perfect H₂ selectivity over N₂. The percent improvement of H₂ permeability decreases with increasing H₂ feed pressure. A new sorption kinetics hypothesis is proposed to elucidate the increase in H₂ permeability of Pd-Ag membranes caused by oxidation. H₂ solubility and sorption rate results were presented to test the new hypothesis. It is found that air oxidation does not change the H₂ solubility in Pd-Ag membranes, but enhances the H₂ sorption kinetics significantly. The extent of kinetics enhancement also decreases with increasing H₂ pressures. The much faster sorption equilibrium implies higher effective H₂ diffusivity at the Pd-Ag membrane surface for the oxidized sample and a higher transfer rate of atomic hydrogen from surface/sub-surface to the membrane bulk that contributes to the increase of H₂ permeability observed in experiments.     

SENSITIVITY ANALYSIS AND OPTIMIZATION OF ELASTIC-PLASTIC STRUCTURES

Elastic-plastic analysis problems formulated as quadratic programming problems involve energy functional and equilibrium and yield constraints that depend on the design, material and loading. In this paper we consider the problem of determining the variation of structural response with respect to variations of these parameters. A general result for discrete structures is presented and implications for optimal design are discussed.     

Progressive ratio schedules of reinforcement.

[Correction Notice: An erratum for this article was reported in Vol 35(2) of Journal of Experimental Psychology: Animal Behavior Processes (see record 2009-05154-003). The URL provided for the supplemental material was incomplete. The complete URL is http://dx.doi.org/10.1037/a0012497.supp] Pigeons' pecks produced grain under progressive ratio (PR) schedules, whose response requirements increased systematically within sessions. Experiment 1 compared arithmetic (AP) and geometric (GP) progressions. Response rates increased as a function of the component ratio requirement, then decreased linearly (AP) or asymptotically (GP). Experiment 2 found the linear decrease in AP rates to be relatively independent of step size. Experiment 3 showed pausing to be controlled by the prior component length, which predicted the differences between PR and regressive ratio schedules found in Experiment 4. When the longest component ratios were signaled by different key colors, rates at moderate ratios increased, demonstrating control by forthcoming context. Models for response rate and pause duration based on Bizo and Killeen (1997) described performance on AP schedules; GP schedules required an additional parameter representing the contextual reinforcement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Possible Role of Circulating Bone Marrow Mesenchymal Progenitors in Modulating Inflammation and Promoting Wound Repair

Circulating bone marrow mesenchymal progenitors (BMMPs) are known to be potent antigen-presenting cells that migrate to damaged tissue to secrete cytokines and growth factors. An altered or dysregulated inflammatory cascade leads to a poor healing outcome. A skin model developed in our previous study was used to observe the immuno-modulatory properties of circulating BMMP cells in inflammatory chronic wounds in a scenario of low skin perfusion. BMMPs were analysed exclusively and in conjunction with recombinant tumour necrosis factor alpha (TNFα) and recombinant hepatocyte growth factor (HGF) supplementation. We analysed the expression levels of interleukin-8 (IL-8) and ecto-5′-nucleotidase (CD73), together with protein levels for IL-8, stem cell factor (SCF), and fibroblast growth factor 1 (FGF-1). The successfully isolated BMMPs were positive for both hemopoietic and mesenchymal markers and showed the ability to differentiate into adipocytes, chondrocytes, and osteocytes. Significant differences were found in IL-8 and CD73 expressions and IL-8 and SCF concentrations, for all conditions studied over the three time points taken into consideration. Our data suggests that BMMPs may modulate the inflammatory response by regulating IL-8 and CD73 and influencing IL-8 and SCF protein secretions. In conclusion, we suggest that BMMPs play a role in wound repair and that their induced application might be suitable for scenarios with a low skin perfusion.     

Dietary Fish Oil Alters DNA Methylation of Genes Involved in Polyunsaturated Fatty Acid Biosynthesis in Muscle and Liver of Atlantic Salmon (Salmo salar)

Adequate dietary supply of eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3) is required to maintain health and growth of Atlantic salmon (Salmo salar). However, salmon can also convert α-linolenic acid (18:3n-3) into eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3) by sequential desaturation and elongation reactions, which can be modified by 20:5n-3 and 22:6n-3 intake. In mammals, dietary 20:5n-3 + 22:6n-3 intake can modify Fads2 expression (Δ6 desaturase) via altered DNA methylation of its promoter. Decreasing dietary fish oil (FO) has been shown to increase Δ5fad expression in salmon liver. However, it is not known whether this is associated with changes in the DNA methylation of genes involved in polyunsaturated fatty acid synthesis. To address this, we investigated whether changing the proportions of dietary FO and vegetable oil altered the DNA methylation of Δ6fad_b, Δ5fad, Elovl2, and Elovl5_b promoters in liver and muscle from Atlantic salmon and whether any changes were associated with mRNA expression. Higher dietary FO content increased the proportions of 20:5n-3 and 22:6n-3 and decreased Δ6fad_b mRNA expression in liver, but there was no effect on Δ5fad, Elovl2, and Elovl5_b expression. There were significant differences between liver and skeletal muscle in the methylation of individual CpG loci in all four genes studied. Methylation of individual Δ6fad_b CpG loci was negatively related to its expression and to proportions of 20:5n-3 and 22:6n-3 in the liver. These findings suggest variations in dietary FO can induce gene-, CpG locus-, and tissue-related changes in DNA methylation in salmon.     

Ammonia chemistry below 1400 K under fuel-rich conditions in a flow reactor

The oxidation of NH₃ under fuel-rich conditions and moderate temperatures has been studied in terms of a chemical kinetic model over a wide range of conditions, based on the measurements of Hasegawa and Sato. Their experiments covered the fuels hydrogen (0 to 80 vol%), carbon monoxide (0 to 95 vol%), and methane (0 to 1.5 vol%), stoichiometries ranging from slightly lean to very fuel rich, temperatures from 300 to 1330 K, and NO levels from 0 to 2500 ppm. A detailed reaction mechanism has been established, based on earlier work on ammonia oxidation in flames and on selective noncatalytic reduction of NO by NH₃. The kinetic model reproduces the experimental trends qualitatively over the full range of conditions covered, and often the predictions are in quantitative agreement with the observations. Using reaction path analysis and sensitivity studies, the major reaction paths have been identified. The comparatively low temperatures in the present study, as well as the presence of NO, promote the reaction path NH₃→NH₂→N₂ (directly or via NNH), rather than the sequence NH₃→NH₂→NH→N important in flames. The major conversion of fuel-N species to N₂ occurs by reaction of amine radicals with NO, in particular NH₂+NO. In the presence of CH₄, NO is partly converted to cyanides by reaction with CH₃. The mechanism is recommended for modeling the reduction of NO by primary measures in the combustion of biomass, since it has been validated under conditions resembling the conversion of early nitrogenous volatile species in a staged combustion process. It is also appropriate for studies of NO formation in the combustion of gas from gasifying coal.