Reduced Oxygen Conditions Research Articles

Inhibition of Listeria monocytogenes and Clostridium botulinum in Uncured Shredded Pork and Turkey Packaged Under Reduced Oxygen Conditions

Cooked, uncured meat products packaged under reduced oxygen packaging conditions require the control of anaerobic and facultative anaerobic pathogens if they are held at temperatures greater than 3°C at retail or consumer level. The objective of this study was to determine the inhibition of Listeria monocytogenes and Clostridium botulinum in cooked, uncured shredded turkey and pork formulated with synthetic or clean-label antimicrobials. Treatments of shredded meat products were prepared with or without antimicrobials using turkey thigh or breast that were cooked to 85°C, shredded, and chilled before inoculation with the target pathogen. L. monocytogenes inoculated samples were stored at 7.2°C, whereas C. botulinum samples were stored at 12.8°C; triplicate samples were assayed every 2 weeks. In the first set of experiments, L. monocytogenes populations increased 2 to 3 logs within 2 weeks of storage at 7.2°C in both meat control treatments without antimicrobials and in pork with 4% lactate-diacetate blend (LD). A 1-log increase was observed in turkey with 4% LD and Pork with 2% cultured dextrose-vinegar-rosemary (CDVR) under the same storage conditions; a 1-log increase was observed in turkey with CDVR at 4 weeks. The second set of experiments tested the effect of pH reduction (to less than 5.5 by the addition of 0.5% citric acid) in combination with 2% CDVR when added to the brine precook or postcook during shredding. Populations of L. monocytogenes increased 4-log within 2 and 4 weeks at 7.2°C for the control turkey and pork formulations, respectively. No growth was observed in 12 weeks for any antimicrobial CDVR-CA treatments regardless of how antimicrobial was added. Similarly, botulinum toxin was detected in both control treatments at week 2 at 12.8°C, but no toxicity was observed in either antimicrobial treatment through 12 weeks. These data suggest that a combination of 2% cultured dextrose-vinegar-rosemary extract plus 0.5% citric acid to reduce pH inhibits the growth of L. monocytogenes and toxin production of C. botulinum in uncured shredded turkey and pork products stored under mild temperature abuse conditions for up to 12 weeks in reduced oxygen packaging.

Biomass residue to carbon dioxide removal: quantifying the global impact of biochar

The Climate Change Conference of Parties (COP) 21 in December 2015 established Nationally Determined Contributions toward reduction of greenhouse gas emissions. In the years since COP21, it has become increasingly evident that carbon dioxide removal (CDR) technologies must be deployed immediately to stabilize concentration of atmospheric greenhouse gases and avoid major climate change impacts. Biochar is a carbon-rich material formed by high-temperature conversion of biomass under reduced oxygen conditions, and its production is one of few established CDR methods that can be deployed at a scale large enough to counteract effects of climate change within the next decade. Here we provide a generalized framework for quantifying the potential contribution biochar can make toward achieving national carbon emissions reduction goals, assuming use of only sustainably supplied biomass, i.e., residues from existing agricultural, livestock, forestry and wastewater treatment operations. Our results illustrate the significant role biochar can play in world-wide CDR strategies, with carbon dioxide removal potential of 6.23 ± 0.24% of total GHG emissions in the 155 countries covered based on 2020 data over a 100-year timeframe, and more than 10% of national emissions in 28 countries. Concentrated regions of high biochar carbon dioxide removal potential relative to national emissions were identified in South America, northwestern Africa and eastern Europe.Graphical abstract

Multiphase Porous Electrode Theory for the Next Generation of SOFC/SOEC Electrodes

The mixed-ionic electronic conduction (MIEC) of gadolinium doped ceria (CGO) under reduced oxygen conditions makes it an excellent fuel electrode material for SOFC/SOEC applications. As part of a composite electrode (Ni/CGO), the nickel phase offers a fast electronic conduction pathway to the current collector and may act as an electrocatalyst at the three-phase boundary. Although the Ni/CGO cermet provides superior electrochemical performance compared with older technologies such as Ni/YSZ, the models used to study MIEC materials do not capture the unique transport and kinetic physics which makes them an excellent choice for the next generation of fuel electrodes. Within the framework of multiphase porous electrode theory, this work provides a novel set of differential-algebraic equations which captures the effects of the activation overpotential on electronic defect concentration, electrostatic surface potential and ionic transport to accurately predict the current-voltage behaviour of the Ni/CGO electrode. Moreover, through concerted electron and proton tunnelling events, we unify the theory of the electrostatic surface potential with proton-coupled electron transfer kinetics.

Burning questions: Experiments on the effects of charring on domestic and wild sorghum

Sorghum was first domesticated approximately 6000 years ago in the eastern Sahel region of Africa, but our understanding of its agricultural history is uneven due to the paucity of the available archaeobotanical evidence. Despite growing interest in the issue, sorghum response to fire exposure has been little investigated. In this paper, the resistance of six domesticated sorghum varieties (Sorghum bicolor) and one wild specimen (Sorghum arundinaceum) to charring was evaluated under oxidising and reduced oxygen conditions using temperatures ranging from 300 °C to 500 °C for 1–8 h. The experimental study in this work indicates that the maximum temperature wild sorghum can resist without severe distortion is around 300 °C, whereas domesticated varieties could resist up to 350 °C before becoming damaged beyond identification. Our findings suggest that resistance to temperature might represent an important bias for sorghum seed preservation, both in its wild and domesticated forms.

Effect of Physicochemical Characteristics and Storage Atmosphere on Microbiological Stability and Shelf-Life of Minimally Processed European Sea Bass (Dicentrarchus labrax) Fillets

The aim of the present work was to evaluate the effect of various hurdles such as aw and pH as well as the storage atmosphere on the microbiological and sensory changes of minimally processed (lightly brined or marinated with acetic or citric acid) European sea bass (Dicentrarchus labrax) fillets. The results indicated that the shelf-life of brined fillets stored aerobically was 6 d while that of vacuum and MAP-stored was 12 d, since a reduced growth rate of spoilage bacteria was recorded. The physicochemical characteristics such as aw and water phase salt (WPS) were not considerably changed, while the oxygen levels into the packages ensure the microbiological safety of the product. The fillets marinated with acetic acid exhibited a longer shelf-life at 30 and 40 d under aerobic and reduced oxygen conditions, respectively, while the products marinated with citric acid were at 25 and 35 d respectively. A low pH resulted in reduced or even limited microbial levels, especially for the fillets marinated with acetic acid; something that ensures microbiological safety as well. The low or limited microbial levels in conjugation with the sensory attributes indicated that spoilage may be due to other mechanisms such as autolysis rather than microbial activity. Overall, the present work highlights the potential for further research and development of minimally processed, microbiologically safe and stable with extended shelf-life value added seafood to satisfy the corresponding consumer demands.

Tracing ecological fluctuations during the Middle to Late Jurassic of Jhura, Kutch, India, using foraminifera

The aim of this work is to examine ecological patterns by analyzing the distribution of foraminifera in the Jurassic sediments of the Jhura area, Kutch, India. 87 foraminiferal species were recovered, which were analyzed for paleoecological interpretations. Three techniques were employed: 1) Diversity indices, in which four episodes are identified based on different indices values; 2) Clustering and nMDS ordination approaches identify four assemblages of benthic foraminifera, which differ in biotic and abiotic characteristics; 3) Morphogroup analysis, which divides the studied sequence into four paleoecological units. Four depositional episodes are recognized within the studied interval: Episode I (Bajocian to Bathonian), Spirillina polygyrata assemblage shows the calm environment with a high diversity of foraminiferal species and enough nutrients in the outer shelf zone having normal salinity and high level of dissolved oxygen. Episode II (Lower Callovian), Miliammina cf. M. valdensis assemblage occurred in a stressed condition with low diversity of species in a shallower portion of mid-shelf in a hypo-saline environment and reduced oxygen condition having low to average food influx. Episode III (Middle to Upper Callovian), Lenticulina subalata assemblage indicates that this portion deposited in stress-free environmental conditions having normal salinity and well‑oxygenated waters in the deepest section of the outer shelf region with high nutrient supply. Episode IV (Oxfordian), Lenticulina bulla assemblage thrived in hyposaline conditions with low oxygen levels and enough nutrients in the deeper portion of the mid-shelf region. An unstable oceanic shelf is interpreted during the deposition of the examined section because of the fluctuations in all inferred parameters.

Abstract P1049: Determination Of Proteome-wide Post-translational Modifications By Lysine Acetylation In Ischemic Cardiac Cells

Introduction: In ischemic cardiomyopathy, cardiac muscle gets damaged due to ischemia and the heart loses its ability to pump blood properly, leading to heart failure. Considering the effect of ischemic cardiomyopathy on the global population, it is vital to understand the impact of ischemia on the cardiac cells and how ischemic condition changes different cellular functions through post-translational modifications (PTM) of cellular proteins. Acetylation, one such PTM, is known to affect protein synthesis, epigenetic modification, and metabolism. This study aims to identify global acetylation changes due to ischemic conditions. Methods: Rat ventricular cardiomyocytes were exposed to reduced oxygen conditions for 12 hours, and the proteins were isolated for acetylation analysis. Mass spectrometry was performed on these proteins to analyze global changes in acetylation due to ischemia. Results: Our result shows that 180 proteins are differentially acetylated during ischemia, and these acetylated proteins are found to be localized in different subcellular organelles like mitochondria, nucleus, cytoplasm, etc. These PTMs tune the cellular protein function and regulate different cellular functions such as protein synthesis, epigenetic modification, and metabolism. Conclusion: Understanding cellular changes due to post-translational acetylation modification may help in the design of therapeutic agents against ischemia-mediated heart disease.

High-frequency modification of the central Mediterranean seafloor environment over the last 74 ka

Here we present a high-resolution record of benthic foraminiferal assemblages for the last 74 kyr from the Sicily Channel Ocean Drilling Program Leg 160 Site 963. Benthic foraminiferal results are compared with geochemical (benthic and planktic δ 18 O and δ 13 C) and calcareous plankton data, previously acquired on the same marine core sediments. Within the succession, three benthic foraminifera compositional zones were defined. Temporal changes in the assemblages are interpreted in the context of the modification of subtropical and temperate climate systems that affected the Mediterranean thermohaline circulation. A close connection between bottom conditions in the Sicily Channel and eastern Mediterranean Sea is evident in two intervals, characterized in the ODP Site 963 by reduced oxygen conditions. The first one, around 53–51 ka, is tentatively attributed to the ‘missing’ sapropel S2 while the second, between 35 and 29 ka, is marked by short and recurrent episodes of bottom-water oxygen decrease. Both are related to a weakening of the intermediate circulation in the Sicily Channel connected with relatively high northern hemisphere summer insolation and increase in Nile River discharge, which inhibited vertical mixing and intermediate water ventilation in Eastern Mediterranean Sea. Over the last deglaciation, the African humid period (AHP) and the sea level rise, also influenced the water mass structure in the Sicily Channel and a reduction of the bottom ventilation is suggested by a strong reduction of deep-water Miliolids. Decreased bottom oxygen levels, which testifies for a weakening of intermediate circulation in Sicily Strait, also characterized the interval corresponding to S1 deposition. Yet, the strong decrease of benthic foraminiferal abundance related to a low surface water trophic level, appears to be conditioned by the reduction of trophic levels in the western Mediterranean. The very high relative abundance of U. mediterranea recorded during this interval is explained by the availability of organic matter during a limited short year period and/or the availability of more degraded organic matter from river runoff. In general, compositional data analysis highlighted a quite complex response of benthic foraminifera to paleoclimatic changes. However, changes in the benthic foraminiferal assemblages recorded during the last glacial are coherent with surface paleoproductivity dynamics connected with D-O oscillation, and support oligotrophic, meso-eutrophic and oligo-mesotrophic conditions during the early interstadials, late interstadials and stadials, respectively. • High-resolution ODP963 (Sicily Channel) Last Glacial to Holocene benthic record. • Dansgaard-Oeschger imprints in bottom environments. • Connection between western and eastern Mediterranean dynamics. • Relationships between Levantine Intermediate Water flow and bottom ventilation.

Nitroreduction of flutamide by Cunninghamella elegans NADPH: Cytochrome P450 reductase

The microbial model of mammalian drug metabolism, Cunninghamella elegans, has three cytochrome P450 reductase genes in its genome: g1631 (CPR_A), g4301 (CPR_B), and g7609 (CPR_C). The nitroreductase activity of the encoded enzymes was investigated via expression of the genes in the yeast Pichia pastoris X33. Whole cell assays with the recombinant yeast demonstrated that the reductases converted the anticancer drug flutamide to the nitroreduced metabolite that was also produced from the same substrate when incubated with human NADPH: cytochrome P450 reductase. The nitroreductase activity extended to other substrates such as the related drug nilutamide and the environmental contaminants 1-nitronaphthalene and 1,3-dinitronaphthalene. Comparative experiments with cell lysates of recombinant yeast were conducted under aerobic and reduced oxygen conditions and demonstrated that the reductases are oxygen sensitive.

Paleoenvironments and Hydrocarbon Potential of Upper Cretaceous Shales in Agbabu-1 Well, Dahomey Basin – Insight from Geochemistry and Foraminifera Paleontology

Upper Cretaceous shales partially exposed in the northern fringes of the Dahomey Basin are well developed in the subsurface in Southwestern part of the basin where Agbau-1 well is sited. These shales were evaluated in respect to their paleoenvironments and potentials for hydrocarbon using foraminiferal assemblages, biomarkers and Rock Eval pyrolysis studies. The dominance of benthonic foraminifera species suggests a shallow marine environment and high percentage of calcareous to arenaceous benthic www.eujournal.org 195 foraminifera indicate high water salinity and hypersline environment. Dysoxic oxygen condition is also prevalent probably because most of the benthic foraminifera recovered are epifauna that live in a reduced oxygen condition. 1.90 wt%, 244 mgHC/gTOC and 429℃ average values of total organic carbon, hydrogen index and Tmax reveal that the Upper Cretaceous shales have relatively fair to good organic matter, predominantly Type II-III kerogen and currently immature. Though three is a trend of an increase in maturity down the hole. All the steranes have uniform distributions (C27>C28>C29), suggesting a relatively higher input from the marine red algae and a low level of land plant contribution to the source organic matter. Pristane/phytane ratios and C29/C27 steranes confirmed the organic matter type to be a Type II/III and anoxic source rock depositional condition as well as a reducing diagenetic system in the sediment water column. The Upper Cretaceous shales in Dahomey Basin can be targeted for exploration as an unconventional petroleum resource.

Laser induced incandescence measurement of soot in ethylene buoyant turbulent diffusion flames under normal and reduced oxygen concentrations

There is a lack of published soot measurement data in buoyant turbulent flames under reduced oxygen conditions. In this work, the laser induced incandescence (LII) technique is used to investigate the soot volume fraction (fv) and soot sheet thickness in buoyant turbulent diffusion flames in atmospheres with different oxygen concentrations (OC, oxygen molar fraction in oxidizer). The experiments establish an extensive database of quantitative fv spatial distribution in ethylene flames under three OCs (20.9%, 16.8%, and 15.2%) and two heat release rates (HRR = 10 kW and 15 kW). Mean, fluctuation, and probability density function of fv, as well as local soot intermittency are studied and compared across different conditions. The results show that the maximum instantaneous fv in normal air can be ~8 ppm; but the corresponding mean fv only reaches up to 0.58 ppm due to turbulence and flame intermittency. As the oxygen concentration is reduced from 20.9% to 15.2%, the mean fv decreases, and this effect is more significant at lower heights above the burner (e.g., ~75% reduction in the mean fv at a height of half a burner outer diameter). Soot is found to be distributed unevenly in the flame, appearing in sheet-like regions with irregular and complicated shapes. The soot sheet thickness is quantified to better understand soot-turbulence interactions. This soot dataset, along with other accompanying radiation and flow field measurements, provides a comprehensive understanding of the dynamics of turbulent buoyant flame dynamics under normal and vitiated conditions, and can be used to develop and validate models for soot formation and radiative heat transfer in such flames.

DNMT3B Is an Oxygen-Sensitive De Novo Methylase in Human Mesenchymal Stem Cells.

The application of physiological oxygen (physoxia) concentrations is becoming increasingly commonplace within a mammalian stem cell culture. Human mesenchymal stem cells (hMSCs) attract widespread interest for clinical application due to their unique immunomodulatory, multi-lineage potential, and regenerative capacities. Descriptions of the impact of physoxia on global DNA methylation patterns in hMSCs and the activity of enzymatic machinery responsible for its regulation remain limited. Human bone marrow-derived mesenchymal stem cells (BM-hMSCs, passage 1) isolated in reduced oxygen conditions displayed an upregulation of SOX2 in reduced oxygen conditions vs. air oxygen (21% O2, AO), while no change was noted for either OCT-4 or NANOG. DNA methylation marks 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) showed decreases in 2% O2 environment (workstation) (2% WKS). DNMT3B (DNA methyltransferase 3B) and TET1 (Ten-eleven translocation enzyme 1) displayed reduced transcription in physoxia. Consistent with transcriptional downregulation, we noted increased promoter methylation levels of DNMT3B in 2% WKS accompanied by reduced DNMT3B and TET1 protein expression. Finally, a decrease in HIF1A (Hypoxia-inducible factor 1A) gene expression in 2% WKS environment correlated with protein levels, while HIF2A was significantly higher in physoxia correlated with protein expression levels vs. AO. Together, these data have demonstrated, for the first time, that global 5mC, 5hmC, and DNMT3B are oxygen-sensitive in hMSCs. Further insights into the appropriate epigenetic regulation within hMSCs may enable increased safety and efficacy development within the therapeutic ambitions.

Pressure Sensitivity of Charge Conduction Through the Interface Between a Metal Oxide Nanocrystallite and Graphene

AbstractHighly sensitive, micron‐size, lightweight, and cost‐effective pressure sensors and pressure sensor arrays are in demand for varieties of sonic, biomedical, tactile, and wearable microelectronic applications. Here, the electrical conduction through the interface between a metal oxide semiconductor nanocrystallite and graphene (Gr) formed in O‐rich conditions is shown to be highly pressure sensitive, and a novel class of pressure sensors operating based on the electronic features of heterointerfaces is introduced. First‐principle studies on ZnO/Gr interface attribute the observed pressure sensitivity to the spontaneous formation of a sparse layer of oxygen at the O‐terminated ZnO/Gr interface. Strained by the external force, this layer controls the electron conduction through the junction. In the reduced oxygen conditions, the formation of a stable and pressure insensitive Zn‐terminated ZnO/Gr junction is predicted, which reversibly transforms to the former upon annealing in air at 300 °C. The presented results concerning the spontaneity of adsorbing oxygen species to the O‐terminated metal oxide/Gr junctions are anticipated to assist understanding and engineering of the piezoresistivity and chemiresistivity in the metal oxide‐Gr composites.

Nitrogen addition alters composition, diversity, and functioning of microbial communities in mangrove soils: An incubation experiment

Mangrove ecosystems are important for carbon storage due to their high productivity and low decomposition rates. Waterways have experienced increased nutrient loads as a result of anthropogenic activities and it is unclear how this may affect carbon and nutrient cycles in downstream mangroves that receive these nutrient-rich waters. Using a laboratory-based incubation experiment, this study aimed to assess the effects of nutrient addition on the diversity and structure of mangrove soil bacterial communities, as well as biomass and activity of the soil microbial community, under different oxygen conditions. Bacterial community diversity and composition was characterised using 16S rRNA gene sequencing and microbial activity was examined through the measurement of microbial respiration and the activities of enzymes associated with organic matter decomposition. Nitrogen addition caused clear shifts in bacterial community composition, with decreases in bacterial diversity and the abundance of sulfate-reducing bacteria. Microbial biomass also decreased with nitrogen addition under reduced oxygen incubations. Changes in bacterial community structure were accompanied by changes in the activity of some enzymes involved in carbon, nitrogen, and phosphorus cycling. Under reduced oxygen conditions, nitrogen addition resulted in a significant increase in the microbial metabolic quotient but no accompanying change in microbial respiration, which was explained by a decrease in microbial biomass. The findings of this study indicate that nitrogen loading has potential implications for microbial communities and carbon and nutrient cycling in mangrove environments that warrant further investigation under field conditions.

Ichnofabrics and their roles in the modification of petrophysical properties: A case study of the Ordovician Majiagou Formation, northwest Henan Province, China

The carbonate rocks of the Ordovician Majiagou Formation from the northwestern part of Henan Province and their diverse trace fossils provide an outcrop analogue for bioturbated, low porosity and low permeability carbonate reservoirs. Three ichnofabrics can be defined based on the ichnotaxonomy, ichnodiversities, individual abundances and overall bioturbation indices. The Balanoglossites ichnofabric represented medium to relatively high-energy sedimentary environments such as intertidal zone and subtidal shoals in the carbonate platform. The Planolites ichnofabric suggested relatively low-energy, protected sedimentary environments such as lagoons in a restricted carbonate platform, but also occurs in the deeper-water depressions in the open carbonate platform. The Chondrites ichnofabric characterized low-energy and reduced oxygen conditions, with burrows penetrating below a shallow redox interface in deeper-water settings that include the distal slope as well as local depressions in the open carbonate platform. Our analysis suggests that the modifications of petrophysical parameters are controlled or influenced by the ichnofabric characteristics (burrow architecture, burrow cross-cutting relationship, degree of bioturbation and burrow connectivity), the permeability contrast between burrow-fills and matrix, and the dolomitization of burrow-fills. The micritic host sediments have negligible porosity and permeability. The bioturbated sediments have significant differences in fabric, texture, porosity and permeability. The burrow-fills are very commonly dolomitised. Each of the burrow-types can enhance reservoir properties, but the greatest differences are associated with the Balanoglossites ichnofabric, in which porosity and permeability can reach over 2% and 70 mD. Preliminary stratigraphic studies indicate that reservoir potential in the subsurface will be linked to an understanding of the distribution of shoal and intertidal facies as well as their associated Balanoglossites ichnofabrics.

Hypoxia-Inducible Lysine Methyltransferases: G9a and GLP Hypoxic Regulation, Non-histone Substrate Modification, and Pathological Relevance.

Oxygen sensing is inherent among most animal lifeforms and is critical for organism survival. Oxygen sensing mechanisms collectively trigger cellular and physiological responses that enable adaption to a reduction in ideal oxygen levels. The major mechanism by which oxygen-responsive changes in the transcriptome occur are mediated through the hypoxia-inducible factor (HIF) pathway. Upon reduced oxygen conditions, HIF activates hypoxia-responsive gene expression programs. However, under normal oxygen conditions, the activity of HIF is regularly suppressed by cellular oxygen sensors; prolyl-4 and asparaginyl hydroxylases. Recently, these oxygen sensors have also been found to suppress the function of two lysine methyltransferases, G9a and G9a-like protein (GLP). In this manner, the methyltransferase activity of G9a and GLP are hypoxia-inducible and thus present a new avenue of low-oxygen signaling. Furthermore, G9a and GLP elicit lysine methylation on a wide variety of non-histone proteins, many of which are known to be regulated by hypoxia. In this article we aim to review the effects of oxygen on G9a and GLP function, non-histone methylation events inflicted by these methyltransferases, and the clinical relevance of these enzymes in cancer.

Resistant moulds as pasteurization target for cold distributed high pressure and heat assisted high pressure processed fruit products

High pressure processing (HPP), also known as high hydrostatic pressure (HHP) is a modern method of food pasteurization used commercially in many countries. It relies on the application of very high pressures (up to 600 MPa) to the food/beverage to inactivate microorganisms. Since no heat or mild heat is applied, most of the original food sensory, nutrient and functional properties are retained after processing, and fresh-like fruit products with longer shelf-life are produced. In this study, a review of the resistance to HPP and HPTP (high pressure thermal process) of key bacteria, moulds and yeasts which often contaminate fruit products was undertaken. Spores of moulds Byssochlamys nivea - anamorph name Paecilomyces niveus or Neosartorya fischeri - anamorph name Aspergillus fischeri, are very resistant. A HPTP process of 600 MPa-75°C-15 min only caused a reduction of 1.4 log. Moulds are able to grow at temperatures between 10 and 43 °C, water activity between 0.892 and 0.992, over a wide range of pH (3–8), under reduced oxygen conditions inside food packs and in carbonated beverages, sometimes producing mycotoxins. Furthermore, HPP treated fruit products are cold stored, and therefore moulds can be an issue as they grow at temperatures as low as 10 °C. Therefore, in view of the acidity of fruit products, the high resistance to HPTP in particular older spores, the use of B. nivea or N. fischeri spores as reference microorganisms in the design of new HPP and HPTP processes with fruit products was proposed.

Substantial vegetation response to Early Jurassic global warming with impacts on oceanic anoxia

Rapid global warming and oceanic oxygen deficiency during the Early Jurassic Toarcian Oceanic Anoxic Event at around 183 Ma is associated with a major turnover of marine biota linked to volcanic activity. The impact of the event on land-based ecosystems and the processes that led to oceanic anoxia remain poorly understood. Here we present analyses of spore–pollen assemblages from Pliensbachian–Toarcian rock samples that record marked changes on land during the Toarcian Oceanic Anoxic Event. Vegetation shifted from a high-diversity mixture of conifers, seed ferns, wet-adapted ferns and lycophytes to a low-diversity assemblage dominated by cheirolepid conifers, cycads and Cerebropollenites-producers, which were able to survive in warm, drought-like conditions. Despite the rapid recovery of floras after Toarcian global warming, the overall community composition remained notably different after the event. In shelf seas, eutrophication continued throughout the Toarcian event. This is reflected in the overwhelming dominance of algae, which contributed to reduced oxygen conditions and to a marked decline in dinoflagellates. The substantial initial vegetation response across the Pliensbachian/Toarcian boundary compared with the relatively minor marine response highlights that the impacts of the early stages of volcanogenic global warming were more severe for continental ecosystems than marine ecosystems. Global warming impacts during the Toarcian Oceanic Anoxic Event were initially more severe for terrestrial ecosystems than marine ecosystems, and included a loss of vegetation diversity, according to spore–pollen assemblage data from Pliensbachian–Toarcian rock samples.

A Strain Gauge Monitor (SGM) for Continuous Valve Gape Measurements in Bivalve Molluscs in Response to Laboratory Induced Diel-cycling Hypoxia and pH.

An inexpensive, laboratory-based, strain gauge valve gape monitor (SGM) was developed to monitor the valve gape behavior of bivalve molluscs in response to diel-cycling hypoxia. A Wheatstone bridge was connected to strain gauges that were attached to the shells of oysters (Crassostrea virginica). The recorded signals allowed for the opening and closing of the bivalves to be recorded continuously over two-day periods of experimentally-induced diel-cycling hypoxia and diel-cycling changes in pH. Here, we describe a protocol for developing an inexpensive strain gauge monitor and describe, in an example laboratory experiment, how we used it to measure the valve gape behavior of Eastern oysters (C. virginica), in response to diel-cycling hypoxia and cyclical changes in pH. Valve gape was measured on oysters subjected to cyclical severe hypoxic (0.6 mg/L) dissolved oxygen conditions with and without cyclical changes in pH, cyclical mild hypoxic (1.7 mg/L) conditions and normoxic (7.3 mg/L) conditions. We demonstrate that when oysters encounter repeated diel cycles, they rapidly close their shells in response to severe hypoxia and close with a time lag to mild hypoxia. When normoxia is restored, they rapidly open again. Oysters did not respond to cyclical pH conditions superimposed on diel cycling severe hypoxia. At reduced oxygen conditions, more than one third of the oysters closed simultaneously. We demonstrate that oysters respond to diel-cycling hypoxia, which must be considered when assessing the behavior of bivalves to dissolved oxygen. The valve SGM can be used to assess responses of bivalve molluscs to changes in dissolved oxygen or contaminants. Sealing techniques to better seal the valve gape strain gauges from sea water need further improvement to increase the longevity of the sensors.

Anomalous effect of UV light on the humidity dependence of photocurrent in perovskite solar cells

Effect of oxygen on the humidity dependence of photocurrent in the presence of UV light has been studied for perovskite solar cells. We observed that the magnitude of photocurrent increases with decreasing humidity initially, but below a certain level, the photocurrent starts to decrease when the humidity is reduced by sending dry nitrogen gas. If we decrease the humidity by sending dry air (keeping nitrogen to oxygen ratio same), then this effect is absent. This phenomenon is related to the presence of oxygen in the environment. When humidity is decreased by flowing dry nitrogen, the oxygen present in the environment of perovskite solar cell also reduces. We found that in the reduced oxygen condition, the presence of UV light helps to remove oxygen from the surface of the mesoporous TiO2 which is responsible for the reduction of photocurrent. In the presence of white light, this effect is not observed. To understand the phenomenon we studied low-frequency noise and current–voltage characteristics, and the dielectric properties of perovskite solar cells under various conditions.