Corrosion Testing of Ni Alloy HVOF Coatings in High Temperature Environments for Biomass Applications

This paper reports the corrosion behavior of Ni alloy coatings deposited by high velocity oxyfuel spraying, and representative boiler substrate alloys in simulated high temperature biomass combustion conditions. Four commercially available oxidation resistant Ni alloy coating materials were selected: NiCrBSiFe, alloy 718, alloy 625, and alloy C-276. These were sprayed onto P91 substrates using a JP5000 spray system. The corrosion performance of the coatings varied when tested at ~525, 625, and 725 °C in K₂SO₄-KCl mixture and gaseous HCl-H₂O-O₂ containing environments. Alloy 625, NiCrBSiFe, and alloy 718 coatings performed better than alloy C-276 coating at 725 °C, which had very little corrosion resistance resulting in degradation similar to uncoated P91. Alloy 625 coatings provided good protection from corrosion at 725 °C, with the performance being comparable to wrought alloy 625, with significantly less attack of the substrate than uncoated P91. Alloy 625 performs best of these coating materials, with an overall ranking at 725 °C as follows: alloy 625 > NiCrBSiFe > alloy 718 ? alloy C-276. Although alloy C-276 coatings performed poorly in the corrosion test environment at 725 °C, at lower temperatures (i.e., below the eutectic temperature of the salt mixture) it outperformed the other coating types studied.     

An Improved Method for Determining Medium- and Long-Chain FAMEs Using Gas Chromatography

The existing protocols for analyzing fatty acid methyl esters (FAMEs) using a one-step acetyl chloride (AC) catalyzed transesterification and extraction procedure cannot accurately determine the medium- and long-chain fatty acids simultaneously in clinical (enteral, parenteral) formulations. For example: (1) addition of AC at room temperature generates an exothermic reaction that often results in loss of sample and possible injury to the analyst; (2) certain polyunsaturated fatty acids (PUFAs) are less stable at elevated temperatures during the transesterification and contribute to the over-estimation of the C16:0 and C18:1 fatty acids; and (3) the flame-ionization detector (FID) response varies depending on the carbon chain length of the fatty acids, that consequently impacts the underestimation of medium-chain fatty acid (C6–C10) recoveries. To overcome these deficiencies and accurately determine FAMEs, we have developed an improved one-step transesterification method that employs the addition of AC in tubes kept on a dry ice bath, the transesterification at room temperature, and the data analysis using relative response factors. Using this modified protocol, we determined the fatty acid composition of lipid emulsions (Omegaven^® and Lipidem^®) on a Shimadzu GC2010 gas chromatography (GC) system using a capillary GC column (Zebron ZB-WAX plus, 30 m, 0.25 mm ID, 0.25 μm). Our data suggest that the improved method can be easily used to accurately determine fatty acids (C6–C24) in functional foods and lipid emulsions.     

Antimicrobial and Anticancer Properties of Synthetic Peptides Derived from the Wasp Parachartergus fraternus

Agelaia-MPI and protonectin are antimicrobial peptides isolated from the wasp Parachartergus fraternus that show antimicrobial and neuroactive activities. Previously, two analogues of these peptides, neuroVAL and protonectin-F, were designed to reduce nonspecific toxicity and improve potency. Here, the three-dimensional structures of neuroVAL, protonectin and protonectin-F were determined by using circular dichroism and NMR spectroscopy. Antibacterial, antifungal, cytotoxic and hemolytic activities were tested for the parent peptides and analogues. All peptides showed moderate antimicrobial activity against Gram-positive bacteria, with agelaia-MPI being the most active. Protonectin and protonectin-F were found to be toxic to cancerous and noncancerous cell lines. Internalization experiments revealed that these peptides accumulate inside both cell types. By contrast, neuroVAL was nontoxic to all tested cells and was able to enter cells without accumulating. In summary, neuroVAL has potential as a nontoxic cell-penetrating peptide, while protonectin-F needs further modification to realize its potential as an antitumor peptide.     

Myeloid-Derived Suppressor Cells Gain Suppressive Function during Neonatal Bacterial Sepsis

Neonates are at an increased risk of an infectious disease. This is consistent with an increased abundance of myeloid-derived suppressor cells (MDSCs) compared with older children and adults. Using a murine model of neonatal bacterial sepsis, we demonstrate that MDSCs modulate their activity during an infection to enhance immune suppressive functions. A gene expression analysis shows that MDSCs increased NOS2, Arg-1 and IL-27p28 expression in vitro and in vivo in response to Escherichia coli O1:K1:H7 and this is regulated at the level of the gene expression. Changes in the effector gene expression are consistent with increased enzymatic activity and cytokine secretion. The neonatal MDSCs express toll-like receptor (TLR) 2, 4 and 5 capable of recognizing pathogen-associated molecular patterns (PAMPS) on E. coli. However, a variable level of effector expression was achieved in response to LPS, peptidoglycan or flagellin. Individual bacterial PAMPs did not stimulate the expression of Arg-l and IL-27p28 equivalently to E. coli. However, the upregulation of NOS2 was achieved in response to LPS, peptidoglycan and flagella. The increased immune suppressive profile translated to an enhanced suppression of CD4+ T cell proliferation. Collectively, these findings increase our understanding of the dynamic nature of MDSC activity and suggest that these cells abundant in early life can acquire activity during an infection that suppresses protective immunity.     

Platelet Inhibition Prevents NLRP3 Inflammasome Activation and Sepsis-Induced Kidney Injury

Platelets, cellular mediators of thrombosis, are activated during sepsis and are increasingly recognized as mediators of the immune response. Platelet activation is significantly increased in sepsis patients compared to ICU control patients. Despite this correlation, the role of activated platelets in contributing to sepsis pathophysiology remains unclear. We previously demonstrated NOD-like receptor protein 3 inflammasome (NLRP3) inflammasome activation in sepsis-induced platelets from cecal-ligation puncture (CLP) rats. Activated platelets were associated with increased pulmonary edema and glomerular injury in CLP vs. SHAM controls. In this study, we investigated whether inhibition of platelet activation would attenuate NLRP3 activation and renal and pulmonary injury in response to CLP. CLP was performed in male and female Sprague Dawley (SD) rats (n = 10/group) to induce abdominal sepsis and SHAM rats served as controls. A subset of CLP animals was treated with Clopidogrel (10 mg/kg/day, CLP + CLOP) to inhibit platelet activation. At 72 h post-CLP, platelet activation and NLRP3 inflammasome assembly were evaluated, IL-1β and IL-18 were measured in plasma, and tissues, renal and pulmonary pathology, and renal function were assessed. Activated platelets were 7.8 ± 3.6% in Sham, 22 ± 6% in CLP and significantly decreased to 14.5 ± 0.6% in CLP + CLOP (n = 8–10/group, p < 0.05). NLRP3 inflammasome assembly was inhibited in platelets of CLP + CLOP animals vs. CLP. Significant increases in plasma and kidney IL-1β and IL-18 in response to CLP were decreased with Clopidogrel treatment. Renal injury, but not lung histology or renal function was improved in CLP + CLOP vs. CLP. These data provide evidence that activated platelets may contribute to sepsis-induced renal injury, possibly via NLRP3 activation in platelets. Platelets may be a therapeutic target to decrease renal injury in septic patients.     

African lake management initiatives: The global connection

There is a global dimension to lake management in Africa and elsewhere that will require a concerted action not only from individual riparian states, but also from regional, continental and global communities. The current global lake threats arise from climate change, regional land degradation and semivolatile contaminants, and share the common feature that the atmosphere is the vector that spreads their impacts over large areas and to many lakes. The Great Lakes of Africa (Malawi, Victoria and Tanganyika) are particularly sensitive to these problems because of their enormous surface areas, slow water flushing rates, and the importance of direct rainfall in their water budgets. Their response times might be slow to yield a detectable change and, unfortunately, their recovery times might also be slow. It is possible for atmospheric effects to act antagonistically to the impacts of catchment change, but antagonistic effects could become synergistic in the future. Improved understanding of the physical dynamics of these lakes, and development of models linking their physical and biogeochemical behaviour to regional, mesoscale climate models, will be necessary to guide lake managers.     

The Great Lakes Cladophora Model: Development,testing, and application to Lake Michigan

A recent review of the Great Lakes Water Quality Agreement has concluded that while controls on phosphorus inputs to Lake Michigan achieved the desired effect in offshore waters, the nearshore region continues to suffer from elevated phosphorus levels. Failure to achieve trophic state goals in the nearshore is manifested in nuisance growth of Cladophora and attendant impacts on property owners, utilities, and the public health and welfare. This study focuses on a site in Lake Michigan near Milwaukee, Wisconsin, where nuisance growth of Cladophora and associated beach fouling occur regularly. A mechanistic model simulating Cladophora growth, suitable for guiding nutrient management in the Great Lakes nearshore, is presented. The model represents an update of the Canale and Auer framework, reflecting current understandings of Cladophora ecology and offering a user-friendly interface making the software more widely available to decision makers. This Great Lakes Cladophora Model (GLCM) is first validated for the Auer/Canale data set collected in 1979 at a site on Lake Huron and then for a data set developed in 2006 for a site on Lake Michigan. Model performance under the strikingly different forcing conditions (depth, light, phosphorus levels) characteristic of these two sites affirms the widespread applicability of the tool. The GLCM is then extended to examine the impacts of ecosystem perturbation (dreissenid colonization) on Cladophora growth and to future approaches to monitoring and management.     

Effect of sodium chlorate on Salmonella typhimurium concentrations in the weaned pig gut

Salmonella cause economic losses to the swine industry due to disease and compromised food safety. Since the gut is a major reservoir for Salmonella, strategies are sought to reduce their concentration in pigs immediately before processing. Respiratory nitrate reductase activity possessed by Salmonella also catalyzes the intracellular reduction of chlorate (an analog of nitrate) to chlorite, which is lethal to the microbe. Since most gastrointestinal anaerobes lack respiratory nitrate reductase, we conducted a study to determine if chlorate may selectively kill Salmonella within the pig gut. Weaned pigs orally infected with 8 x 10(7) CFU of a novobiocin- and nalidixic acid-resistant strain of Salmonella Typhimurium were treated 8 and 16 h later via oral gavage (10 ml) with 0 or 100 mM sodium chlorate. Pigs were euthanized at 8-h intervals after receiving the last treatment. Samples collected by necropsy were cultured qualitatively and quantitatively for Salmonella and for most probable numbers of total culturable anaerobes. A significant (P < 0.05) chlorate treatment effect was observed on cecal concentrations of Salmonella, with the largest reductions occurring 16 h after receiving the last chlorate treatment. An observed treatment by time after treatment interaction suggests the chlorate effect was concentration dependent. Chlorate treatment may provide a means to reduce foodborne pathogens immediately before harvest.     

Genotypic variation among arcobacter isolates from a farrow-to-finish swine facility

Arcobacter spp. were isolated from nursing sows and developing pigs on three farms of a farrow-to-finish swine operation and market-age pigs at slaughter. Isolates were identified by polymerase chain reaction and genotypic fragment patterns were examined by pulsed-field gel electrophoresis (PFGE). Incidences of Arcobacter-positive samples increased progressively as the pigs aged, resulting in all of the pens at the end of the growth cycle in the finishing barn containing Arcobacter-positive feces. However, only 10 of 350 cecal samples from slaughtered pigs were positive. There was little similarity between genotypic patterns for Arcobacter collected from the three farms. The level of genotypic variation revealed by PFGE suggested that pigs in this farrow-to-finish operation were colonized by multiple Arcobacter parent genotypes that may have undergone genomic rearrangement, common to members of Campylobacteraceae, during successive passages through the animals. Additionally, the level of genotypic diversity seen among Arcobacter isolates from farms of a single farrow-to-finish swine operation suggests an important role for genotypic phenotyping as a source identification and monitoring tool during outbreaks.     

Comparison of pulp-mill-integrated hydrogen production from gasified black liquor with stand-alone production from gasified biomass

When gasified black liquor is used for hydrogen production, significant amounts of biomass must be imported. This paper compares two alternative options for producing hydrogen from biomass: (A) pulp-mill-integrated hydrogen production from gasified back liquor; and (B) stand-alone production of hydrogen from gasified biomass. The comparison assumes that the same amount of biomass that is imported in Alternative A is supplied to a stand-alone hydrogen production plant and that the gasified black liquor in Alternative B is used in a black liquor gasification combined cycle (BLGCC) CHP unit. The comparison is based upon equal amounts of black liquor fed to the gasifier, and identical steam and power requirements for the pulp mill. The two systems are compared on the basis of total CO₂ emission consequences, based upon different assumptions for the reference energy system that reflect different societal CO₂ emissions reduction target levels. Ambitions targets are expected to lead to a more CO₂–lean reference energy system, in which case hydrogen production from gasified black liquor (Alternative A) is best from a CO₂ emissions’ perspective, whereas with high CO₂ emissions associated with electricity production, hydrogen from gasified biomass and electricity from gasified black liquor (Alternative B) is preferable.