Molecular typing techniques to characterize the development of a lactic acid bacteria community on vacuum-packaged beef

The development of a community of lactic acid bacteria from vacuum-packaged beef was investigated during a 6-week storage trial at 2 degrees C. The lactic acid bacteria population was monitored by using molecular techniques to identify a random sample of isolates at biweekly intervals during the storage trial. The polymerase chain reaction and a randomly amplified polymorphic DNA technique were used to identify and distinguish populations of lactic acid bacteria that developed during the storage trial. At week 0, the population of lactic acid bacteria was 3.5 log cfu/120 cm2 and by week 6, the population reached a maximum of 7.6 log cfu/120 cm2. A sampling from the week 0 population indicated a mixed community of Lactobacillus curvatus, Lactobacillus sakei and Leuconostoc spp. However, the sampling from week 6 indicated the population composition had changed to one where a single Leuconostoc strain predominated. This strain demonstrated antagonism towards the growth of other lactic acid bacteria isolated during the study. Additionally, the strain inhibited the growth of foodborne pathogens Escherichia coli O157:H7 and Listeria monocytogenes. DNA sequence data from the 16S rRNA gene suggested that the isolate may be a Leuconostoc gelidum strain.     

Cost-effective energy carriers for transport – The role of the energy supply system in a carbon-constrained world

The aim of this study is to examine how the options for producing electricity, fuels, and heat in a carbon-constrained world affect the cost-effectiveness of a range of fuels and propulsion technologies in the transportation sector. GET 7.0, a global energy system model with five end-use sectors, is used for the analysis. We find that an energy system dominated either by solar or by nuclear tends to make biofuels in plug-in hybrids cost-effective. If coal with carbon capture and storage (CCS) dominates the energy system, hydrogen cars, rather than plug-in hybrids tend to become cost-effective. Performing a Monte Carlo simulation, we then show that the general features of our results hold for a wide range of assumptions for the costs of vehicle propulsion technologies (e.g., batteries and fuel cells). However, sufficiently large changes in say the battery costs may overturn the impact of changes in the energy supply system, so that plug-in hybrid vehicles become cost-effective even if coal with CCS dominate the energy supply. We conclude that analyses of future energy carriers and propulsion technologies need to consider developments in the energy supply system.     

Consumer impacts on dividends from solar water heating

Common domestic solar water heating system usage patterns were investigated by a survey of 55 installations. These usage patterns were modelled by simulation based on the actual occupants' use of boiler or other auxiliary heating control strategies. These strategies were not optimal, as often assumed. The effectiveness of the technology was found to be highly sensitive to the time settings used for auxiliary water heating, and the 65% of solar householders using their boilers in the mornings were found to be forgoing 75% of their potential savings. Additionally, 92% of consumers were found to be small households, whose potential savings were only 23% of those of larger households, which use more hot water. Overall the majority (at least 60%) of the systems surveyed were found to be achieving no more than 6% of their potential savings. Incorporating consideration of Legionella issues, results indicate that if solar thermal technology is to deliver its potential to CO₂ reduction targets: solar householders must avoid any use of their auxiliary water heating systems before the end of the main warmth of the day, grants for solar technology should be focused on households with higher hot water demands, and particularly on those that are dependent on electricity for water heating, health and safety requirements for hot water storage must be reviewed and, if possible, required temperatures should be set at a lower level, so that carbon savings from solar water heating may be optimized.     

Chemical Ecology of the Defense of Two Nymphalid Butterfly Larvae Against Ants

We analyzed the behavioral responses of the ants Camponotus rufipes and Solenopsis geminata towards all instars of Dione junio and Abananote hylonome. We also analyzed ant behavior towards hexane extracts of larvae and extracts of the spines and neck glands of the fifth instars of both species and identified the chemical compounds present. Larvae of both species were repellent to ants from the first instar onward. Later instars survived ant attacks better than earlier instars. The spines and neck glands of the larvae influenced the behavior of C. rufipes. The chemical compounds contained in the hexane extracts of whole first and fifth instars and in the spines and neck glands of fifth instars were principally carboxylic acids and terpenes. Further bioassays confirmed the repellent effect of some of these acids toward ants.     

Tethered drug release from model contact lenses

Drug delivery to the eye remains a challenge due to low compliance and high amounts of drug loss resulting from anatomical barriers. Contact lens-based delivery systems offer many advantages since their increased corneal residence time can increase drug bioavailability. A releasable, sustained delivery system from a contact lens has been evaluated in the current work. Using a labile lactide spacer, comprised of poly(ethylene glycol) methacrylate, varying numbers of lactide units and succinic anhydride, a model drug, R-roscovitine, was covalently incorporated into model silicone lenses (consisting of 80 mol% N,N-dimethylacrylamide and 20 mol% of a modified silicone). This enabled a greater amount of the drug to remain in the material following extraction with isopropyl alcohol, a common purification procedure used in lens manufacturing. The incorporation of the tether and drug did not substantially alter the bulk properties of the materials, with their water content remaining between 32% and 36% and their transmittance remaining at over 90% at 600 nm. Drug release from these materials exceeded 2 weeks, with the longer lactide tethers showing greater release as expected. This demonstrates that these covalently modified materials have the potential to be used to deliver drugs in a sustained manner. © 2022 Society of Industrial Chemistry.     

Extended Scope and Understanding of Zinc-Dependent Alcohol Dehydrogenases for Reduction of Cyclic α-Diketones

Alcohol dehydrogenases (ADH) are important tools for generating chiral α-hydroxyketones. Previously, only the ADH of Thauera aromatica was known to convert cyclic α-diketones with appropriate preference. Here, we extend the spectrum of suitable enzymes by three alcohol dehydrogenases from Citrifermentans bemidjiense (CibADH), Deferrisoma camini (DecADH), and Thauera phenylacetica (ThpADH). Of these, DecADH is characterized by very high thermostability; CibADH and ThpADH convert α-halogenated cyclohexanones with increased activity. Otherwise, however, the substrate spectrum of all four ADHs is highly conserved. Structural considerations led to the conclusion that conversion of diketones requires not only the expansion of the active site into a large binding pocket, but also the circumferential modification of almost all amino acid residues that form the first shell of the binding pocket. The constellation appears to be overall highly specific for the relative positioning of the carbonyl functions and the size of the C-ring.     

Probing Defects and Spin-Phonon Coupling in CrSBr via Resonant Raman Scattering

Understanding the stability limitations and defect formation mechanisms in 2D magnets is essential for their utilization in spintronic and memory technologies. Here, defects in mono- to multilayer CrSBr are correlated with structural, vibrational, and magnetic properties. Resonant Raman scattering is used to reveal distinct vibrational defect signatures. In pristine CrSBr, it is shown that bromine atoms mediate vibrational interlayer coupling, allowing for distinguishing between surface and bulk defect modes. Environmental exposure is shown to cause drastic degradation in monolayers, with the formation of intralayer defects. This is in contrast to multilayers that predominantly show bromine surface defects. Through deliberate ion irradiation, the formation of defect modes is tuned: these are strongly polarized and resonantly enhanced, reflecting the quasi--1D electronic character of CrSBr. Strikingly, pronounced signatures of spin-phonon coupling of the intrinsic phonon modes and the ion beam-induced defect modes are observed throughout the magnetic transition temperature. Overall, defect engineering of magnetic properties is possible, with resonant Raman spectroscopy serving as a direct fingerprint of magnetic phases and defects in CrSBr.     

Cellular Disulfide Bond Formation in Bioactive Peptides and Proteins

Bioactive peptides play important roles in metabolic regulation and modulation and many are used as therapeutics. These peptides often possess disulfide bonds, which are important for their structure, function and stability. A systematic network of enzymes—a disulfide bond generating enzyme, a disulfide bond donor enzyme and a redox cofactor—that function inside the cell dictates the formation and maintenance of disulfide bonds. The main pathways that catalyze disulfide bond formation in peptides and proteins in prokaryotes and eukaryotes are remarkably similar and share several mechanistic features. This review summarizes the formation of disulfide bonds in peptides and proteins by cellular and recombinant machinery.     

Poverty and disrepair: Challenging the myth of ignorance in private sector housing

As private home ownership grows in Europe, so do the problems of maintenance and repair for poorer owners. In England, it has been believed that one obstacle is the owners' apparent satisfaction with poor conditions. This paper deconstructs the questions in the English House Condition Survey 1981 on which that assumption has been based. By reference to other EHCSs and to a research methodology offering a more differentiated approach to establishing residents' views, it suggests that the problem is not ignorance at all. A more subtle understanding of the validity of housing satisfaction questionnaires is needed to develop effective policies of urban renewal.