Isolating the effects of thixotropy in geopolymer pastes

The rheological properties of potassium-based geopolymers were investigated through a series of experiments intended to isolate the influence of shear rate, recovery time, and shear ramping on thixotropy for a greater understanding of geopolymer thixotropic properties within the context of the geopolymer setting reaction. It is shown that for thixotropic disruption to occur a critical shear rate of 100 s⁻¹ must be reached or surpassed, full thixotropic restructuring occurs at around 90–100 min of total undisturbed rest time, and that reaching a state of full thixotropic disturbance heavily depends on subjected processing parameters. In addition, a consistent crossover between the storage and loss modulus within 1–3 min of oscillation during cyclical oscillatory measurements greatly indicates the repeatability and reversibility of thixotropy in geopolymers and the potential for tailorable viscosity. Overall, it is found that geopolymer pastes exhibit strong evidence of thixotropy, which is favorable for additive manufacturing, and that allotted rest time before shear and shear rate greatly influence the overall rheological properties.     

Phage‐mediated transfer of virulence genes

Bacteriophages as accessory genetic elements play a crucial role in the dissemination of genes and the promotion of genetic diversity within bacterial populations. Such horizontal transfer of DNA is critical in the emergence of new pathogenic organisms, through the dissemination of genes encoding virulence factors such as toxins, adhesins and agressins. Phages can transfer genes that are not necessary for bacteriophage persistence and are generally recognised by their ability to convert their host bacteria to new phenotypes. This phenomenon is known as phage conversion. If such converting genes encode for virulence factors, the consequences of phage infection may include increased virulence of the host bacteria, and the conversion of a non‐pathogenic strain to a potentially dangerous pathogen. A number of virulence factors in bacteria causing diseases in plants, animals and humans are encoded by converting phages, the vast majority of which are temperate as opposed to lytic in nature. © 2001 Society of Chemical Industry     

Hydrothermal catalytic production of fuels and chemicals from aquatic biomass

One of the promising avenues for biomass processing is the use of water as a reaction medium for wet or aquatic biomass. This review focuses on the hydrothermal catalytic production of fuels and chemicals from aquatic biomass. Two different regimes for conversion of aquatic biomass in hydrothermal conditions are discussed in detail. The first is hydrothermal liquefaction, and the second is hydrothermal gasification. The goals of these processes are to produce liquid‐fuel‐range hydrocarbons and methane or hydrogen, respectively. The catalytic upgrading of biocrude resulting from noncatalytic liquefaction and the stability and degradation of catalysts in high temperature water are also discussed. The review concludes with a brief discussion of the outlook for and opportunities within the field of hydrothermal catalytic valorization of biomass. Copyright © 2012 Society of Chemical Industry     

Sex Attractant Pheromone of the Luna Moth, <Emphasis Type="Italic">Actias luna</Emphasis> (Linnaeus)

Giant silk moths (Lepidoptera: Saturniidae) typically are not well represented as larvae or adults in community level inventories of Lepidoptera, and as a result, little is known about their population dynamics. Furthermore, in recent years, many species of silk moths appear to have experienced population declines. Volatile sex pheromones are powerful sampling tools that can be used in operational conservation and monitoring programs for insects. Here, we describe the identification of the sex attractant pheromone of a giant silk moth, the luna moth Actias luna. Coupled gas chromatography-electroantennographic detection and gas chromatography-mass spectrometric analyses of extracts from pheromone glands of female luna moths supported the identification of (6E,11Z)-6,11-octadecadienal (E6,Z11–18:Ald), (6E)-6-octadecenal (E6–18:Ald), and (11Z)-11-octadecenal (Z11–18:Ald) as the compounds in extracts that elicited responses from antennae of male moths. These identifications were confirmed by synthesis, followed by testing of blends of the synthetic compounds in field trials in Ontario, Canada, and Kentucky, USA. Male moths were attracted to synthetic E6,Z11–18:Ald as a single component. Attraction appeared to be enhanced by addition of E6–18:Ald but not Z11–18:Ald, suggesting that the luna moth pheromone consists of a blend of E6,Z11–18:Ald and E6–18:Ald.     

Hydrothermal preparation of nanotubular particles of a 1:1 nickel phyllosilicate

Hydrothermal treatment of a mixture of nickel chloride, silicic acid and sodium hydroxide at a relatively low temperature, 250 °C and pressure, 10 MPa gave a 1:1 nickel phyllosilicate, [Ni₃Si₂O₅(OH)₄] composed exclusively of hollow, open ended, multiwall nanotubular particles, up to 200 nm in length. No other phases, in particular no silicate platelets were seen. Previous reports on the hydrothermal preparation of tubular nickel phyllosilicate emphasized the need for high temperatures and pressures (ca 400 °C and 70 MPa), with lower temperature giving mostly small thin plate-like products. The tubular particles obtained also had larger outer diameters, 25–30 nm, and larger inner hollow cores, about 10 nm in diameter than nickel silicate nanotubes prepared at high temperatures and pressures. The XRD pattern of the product matched that of pecoraite, the nickel analogue of the tubular magnesium silicate mineral chrysotile. N₂-sorptometry showed the product was mesoporous with a broad range of pore sizes centred around 170 Å, and a BET surface area of 110 m²/g.     

Quantification of the Bactericidal,Fungicidal, and Sporicidal Efficacy of the JLA Ltd. Ozone Laundering System

The objective of this study was to demonstrate the bactericidal, fungicidal, and sporicidal efficacy of the in-use concentration of ozone in solution generated continuously by the JLA Limited OTEX validated ozone laundering system against a range of typical microorganisms associated with laundering applications. The study used the JLA HC 100 laundering machine as the containment vessel. Test microbial suspensions were introduced directly into the drum of the laundering machine containing a known level of water in the presence of soluble ozone. Using standard microbiological techniques, the numbers of surviving bacteria, mold spores or bacterial spores were determined, and reductions in viable counts were calculated. The following test organisms were employed: Pseudomonas aeruginosa, Methicillin-Resistant Staphylococcus aureus (MRSA), Enterococcus faecalis, E. coli, Acinetobacter baumannii, Aspergillus niger (spores), and Clostridium difficile (spores). All tests used multiple contact times of 0, 1, 3, 5, 7, 11 and 15 minutes at 20 °C±2 °C. Levels of ≤0.25 mg/L of dissolved ozone had minimal effect on the bacteria. Levels of >0.45 mg/L ozone showed good biocidal activity, except against Acinetobacter baumannii, which showed strong resistance to ozone. Against fungal spores, dissolved ozone levels of >1.2 mg/L were required to obtain a 2.8 log reduction. For Clostridium difficile spores, a dissolved ozone level between 0.90 and 1.20 mg/L gave >1.6 log reduction with no discernable spore recovery. In every instance, the control tests (no ozone) recovered levels of microorganisms that proved that the action of the laundering machine has no antimicrobial activity, and that the log reductions obtained are solely due to the effects of dissolved ozone.     

Characterization of Impact Damage in Ultra-High Performance Concrete Using Spatially Correlated Nanoindentation/SEM/EDX

Little work has been done to study the fundamental material behaviors and failure mechanisms of cement-based materials including ordinary Portland cement concrete and ultra-high performance concretes (UHPCs) under high strain impact and penetration loads at lower length scales. These high strain rate loadings have many possible effects on UHPCs at the microscale and nanoscale, including alterations in the hydration state and bonding present in phases such as calcium silicate hydrate, in addition to fracture and debonding. In this work, the possible chemical and physical changes in UHPCs subjected to high strain rate impact and penetration loads were investigated using a novel technique wherein nanoindentation measurements were spatially correlated with images using scanning electron microscopy and chemical composition using energy dispersive x-ray microanalysis. Results indicate that impact degrades both the elastic modulus and indentation hardness of UHPCs, and in particular hydrated phases, with damage likely occurring due to microfracturing and debonding.     

The Interaction of Diet and Mitochondrial Dysfunction in Aging and Cognition

Aging is inevitable and it is one of the major contributors to cognitive decline. However, the mechanisms underlying age-related cognitive decline are still the object of extensive research. At the biological level, it is unknown how the aging brain is subjected to progressive oxidative stress and neuroinflammation which determine, among others, mitochondrial dysfunction. The link between mitochondrial dysfunction and cognitive impairment is becoming ever more clear by the presence of significant neurological disturbances in human mitochondrial diseases. Possibly, the most important lifestyle factor determining mitochondrial functioning is nutrition. Therefore, with the present work, we review the latest findings disclosing a link between nutrition, mitochondrial functioning and cognition, and pave new ways to counteract cognitive decline in late adulthood through diet.     

Environmental effects on the strength and impact damage resistance of alumina based oxide/oxide ceramic matrix composites

In this study the effects of high temperature and moisture on the impact damage resistance and mechanical strength of Nextel 610/alumina silicate ceramic matrix composites were experimentally evaluated. Composite laminates were exposed to either a 1050°C isothermal furnace-based environment for 30 consecutive days at 6 h a day, or 95% relative humidity environment for 13 consecutive days at 67°C. Low velocity impact, tensile and short beam strength tests were performed on both ambient and environmentally conditioned laminates and damage was characterized using a combination of non-destructive and destructive techniques. High temperature and humidity environmental exposure adversely affected the impact resistance of the composite laminates. For all the environments, planar internal damage area was greater than the back side dent area, which in turn was greater than the impactor side dent area. Evidence of environmental embrittlement through a stiffer tensile response was noted for the high temperature exposed laminates while the short beam strength tests showed greater propensity for interlaminar shear failure in the moisture exposed laminates. Destructive evaluations exposed larger, more pronounced delaminations in the environmentally conditioned laminates in comparison to the ambient ones. External damage metrics of the impactor side dent depth and area directly influenced the post-impact tensile strength of the laminates while no such trend between internal damage area and residual strength could be ascertained.