scholarly journals Effects of Different Nutrient and Trace Metal Concentrations on Growth of the Toxic Dinoflagellate Gymnodinium catenatum Isolated from Korean Coastal Waters

2020 ◽  
Vol 12 (12) ◽  
pp. 4992
Author(s):  
Kyong Ha Han ◽  
Hyun Jung Kim ◽  
Zhun Li ◽  
Joo Yeon Youn ◽  
Kyeong Yoon Kwak ◽  
...  
Keyword(s):  
Growth Rate ◽  
Trace Metals ◽  
Coastal Waters ◽  
Vitamin B1 ◽  
Growth Patterns ◽  
Korean Isolate ◽  
Wide Range ◽  
High Concentrations ◽  
Cell Densities ◽  
Gymnodinium Catenatum

The effects of the addition of nutrients (nitrate: N; phosphate: P; and vitamin B1) and trace metals (iron: Fe; Copper: Cu; and selenium: Se) on the growth of Gymnodinium catenatum, which was isolated from Korean coastal waters, were investigated. The Korean isolate of G. catenatum grew under a wide range of concentrations of N and P. Whilst high concentrations of N (> N: P ratio of 23.5) did not stimulate the growth rate, an enhanced growth rate and cell density were observed with the addition of P. The experimental addition of vitamin B1 revealed that G. catenatum is not dependent on vitamin B1 for growth. Moreover, the addition of Fe and Cu resulted in no significant differences in the growth patterns and rates of G. catenatum between the controls and treatments. It is thus possible that growth of the Korean isolate of G. catenatum does not require high concentrations of Fe and Cu. However, the cell densities were enhanced in the stationary phases of treatments upon addition of Se, and the maximum cell densities were higher than those in the culture experiments upon additions of other nutrient and trace metals. Our findings indicate that G. catenatum prefers P and Se for proliferation, rather than other nutritional sources.

An Investigation on the Performance of an Oxidation Catalyst Using Two-dimensional Simulation with Detailed Reaction Mechanism

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Sreeharsh Nair ◽  
Mayank Mittal
Keyword(s):  
Single Channel ◽  
Catalytic Converter ◽  
Oxidation Catalyst ◽  
Low Temperature Combustion ◽  
Wide Range ◽  
Detailed Reaction Mechanism ◽  
Temperature Combustion ◽  
High Concentrations ◽  
Dimensional Simulation ◽  
Surface Reaction Kinetics

AbstractThe advent of stricter emission standards has increased the importance of aftertreatment devices and the role of numerical simulations in the evolution of better catalytic converters in order to satisfy these emission regulations. In this paper, a 2-D numerical simulation of a single channel of the monolith catalytic converter is presented by using detailed surface reaction kinetics aiming to investigate the chemical behaviour inside the converter. The model has been developed to study the conversion of carbon monoxide (CO) in the presence of propene (C3H6) for low-temperature combustion (LTC) engine application. The inhibition effect of C3H6 over a wide range of CO inlet concentrations is investigated. Considering both low and high levels of CO concentration at the inlet, the 2-D model predicted better results than their corresponding 1-D counterparts when compared with the experimental data from literature. It was also observed that C3H6 inhibition at high temperatures was significant, particularly for high concentrations of CO compared to low concentrations of CO at the inlet.

scholarly journals On the generation of internal waves by river plumes in subcritical initial conditions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. Mendes ◽  
J. C. B. da Silva ◽  
J. M. Magalhaes ◽  
B. St-Denis ◽  
D. Bourgault ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Internal Waves ◽  
Coastal Waters ◽  
Initial Conditions ◽  
Spatial Scales ◽  
River Plumes ◽  
Wide Range ◽  
Near Shore ◽  
Generation Mechanisms ◽  
Douro River

AbstractInternal waves (IWs) in the ocean span across a wide range of time and spatial scales and are now acknowledged as important sources of turbulence and mixing, with the largest observations having 200 m in amplitude and vertical velocities close to 0.5 m s−1. Their origin is mostly tidal, but an increasing number of non-tidal generation mechanisms have also been observed. For instance, river plumes provide horizontally propagating density fronts, which were observed to generate IWs when transitioning from supercritical to subcritical flow. In this study, satellite imagery and autonomous underwater measurements are combined with numerical modeling to investigate IW generation from an initial subcritical density front originating at the Douro River plume (western Iberian coast). These unprecedented results may have important implications in near-shore dynamics since that suggest that rivers of moderate flow may play an important role in IW generation between fresh riverine and coastal waters.

Effect of caffeine on the growth and photosynthetic efficiency of marine macroalgae

2021 ◽  
Vol 64 (1) ◽  
pp. 13-18
Author(s):  
Ira Gray ◽  
Lindsay A. Green-Gavrielidis ◽  
Carol Thornber
Keyword(s):  
Growth Rate ◽  
Photosynthetic Efficiency ◽  
Sublethal Effects ◽  
Marine Species ◽  
Marine Organisms ◽  
Marine Macroalgae ◽  
Chondrus Crispus ◽  
Coastal Environments ◽  
Codium Fragile ◽  
High Concentrations

Abstract Caffeine is present in coastal environments worldwide and there is a need to assess its impact on marine organisms. Here, we exposed two species of ecologically important marine macroalgae (Chondrus crispus and Codium fragile subsp. fragile) to a suite of caffeine concentrations and measured their response. Caffeine concentrations of 10–100 ng L−1 had no significant effect on the growth rate or photosynthetic efficiency of either algae. Extremely high concentrations (100–200 mg L−1), which may occur acutely, produced sublethal effects for both species and mortality in C. fragile subsp. fragile. Our results highlight the need to understand how caffeine impacts marine species.

Application of the EYTEX™ System to the Evaluation of Cosmetic Products and their Ingredients

1992 ◽  
Vol 20 (1) ◽  
pp. 146-163
Author(s):  
Francis H. Kruszewski ◽  
Laura H. Hearn ◽  
Kyle T. Smith ◽  
Janice J. Teal ◽  
Virginia C. Gordon ◽  
...  
Keyword(s):  
Double Blind ◽  
Eye Irritation ◽  
Ocular Irritation ◽  
Rabbit Eye ◽  
Wide Range ◽  
High Concentrations ◽  
Alkaline Membrane ◽  
Positive Agreement

465 cosmetic product formulations and raw ingredients were evaluated with the EYTEX™ system to determine the potential of this in vitro alternative for identifying eye irritation potential. The EYTEX™ system is a non-animal, biochemical procedure developed by Ropak Laboratories, Irvine, CA, that was designed to approximate the Draize rabbit eye irritation assay for the evaluation of ocular irritation. Avon Products Inc. provided all the test samples, which included over 30 different product types and represented a wide range of eye irritancy. All the EYTEX™ protocols available at the time of this study were used. Samples were evaluated double-blind with both the membrane partition assay (MPA) and the rapid membrane assay (RMA). When appropriate, the standard assay (STD) and the alkaline membrane assay (AMA) were used, as well as specific, documented protocol modifications. EYTEX™ results were correlated with rabbit eye irritation data which was obtained from the historical records of Avon Products Inc. A positive agreement of EYTEX™ results with the in vivo assay was demonstrated by an overall concordance of 80%. The assay error was 20%, of which 18% was due to an overestimation of sample irritancy (false positives) and 2% was attributed to underestimation (false negatives). Overestimation error in this study was due in part to the inability of the protocols to accurately classify test samples with very low irritation potential. Underestimation of sample irritancy was generally associated with ethoxylated materials and high concentrations of specific types of surfactants. 100% sensitivity and 85% predictability were described by the data, indicating the efficiency of EYTEX™ in identifying known irritants. A specificity rate of 39% showed the EYTEX™ assay to be weak in discerning non-irritants. However, the EYTEX™ protocols used in this study were not designed to identify non-irritants. A compatibility rate of 99% proved the effectiveness of the EYTEX™ assay in accommodating a diversity of product types. The EYTEX™ system protocols, when used appropriately, can provide a conservative means of assessing the irritant potential of most cosmetic formulations and their ingredients.

scholarly journals Oxygen Is Instrumental for Biological Signaling: An Overview

Oxygen ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 3-15
Author(s):  
John T. Hancock
Keyword(s):  
Oxidative Stress ◽  
Superoxide Anion ◽  
Nitrosative Stress ◽  
Redox Status ◽  
Complex Interplay ◽  
Wide Range ◽  
Form Part ◽  
High Concentrations ◽  
And Control ◽  
Signaling Components

Control of cellular function is extremely complex, being reliant on a wide range of components. Several of these are small oxygen-based molecules. Although reactive compounds containing oxygen are usually harmful to cells when accumulated to relatively high concentrations, they are also instrumental in the control of the activity of a myriad of proteins, and control both the upregulation and downregulation of gene expression. The formation of one oxygen-based molecule, such as the superoxide anion, can lead to a cascade of downstream generation of others, such as hydrogen peroxide (H2O2) and the hydroxyl radical (∙OH), each with their own reactivity and effect. Nitrogen-based signaling molecules also contain oxygen, and include nitric oxide (NO) and peroxynitrite, both instrumental among the suite of cell signaling components. These molecules do not act alone, but form part of a complex interplay of reactions, including with several sulfur-based compounds, such as glutathione and hydrogen sulfide (H2S). Overaccumulation of oxygen-based reactive compounds may alter the redox status of the cell and lead to programmed cell death, in processes referred to as oxidative stress, or nitrosative stress (for nitrogen-based molecules). Here, an overview of the main oxygen-based molecules involved, and the ramifications of their production, is given.

Prostacyclin and cerebral vessel relaxation

1982 ◽  
Vol 57 (3) ◽  
pp. 334-340 ◽  
Author(s):  
Kamal S. Paul ◽  
Eric T. Whalley ◽  
Christine Forster ◽  
Richard Lye ◽  
John Dutton
Keyword(s):  
Angiotensin Ii ◽  
Arterial Spasm ◽  
Cerebral Vessel ◽  
Content Type ◽  
Wide Range ◽  
Potent Vasodilator ◽  
Dose Dependent Fashion ◽  
Basilar Arteries ◽  
High Concentrations

✓ The authors have studied the ability of prostacyclin to reverse contractions of human basilar arteries in vitro that were induced by a wide range of substances implicated in the etiology of cerebral arterial spasm. Prostacyclin (10−10 to 10−6M) caused a dose-related reversal of contractions induced by 5-hydroxytryptamine, noradrenaline, angiotensin II, prostaglandin (PG)F2α, and U-46619 (a thromboxane-A2 mimetic). These agents were tested at concentrations or volumes that produced almost maximum or maximum responses and those that produced approximately 50% of the maximum response. Contractions induced by maximum concentrations of angiotensin II and U-46619 were least affected by prostacyclin. In addition, contractions induced by thromboxane-A2 generated from guinea-pig lung were reversed in a dose-dependent fashion by prostacyclin. This ability of prostacyclin to physiologically antagonize contractions of the human basilar artery in vitro induced by high concentrations of various spasmogenic agents suggests that such a potent vasodilator agent or more stable analogue may be of value in the treatment of such disorders as cerebral arterial spasm following subarachnoid hemorrhage.

scholarly journals Ozone damage, detoxification and the role of isoprenoids – new impetus for integrated models

2016 ◽  
Vol 43 (4) ◽  
pp. 324 ◽  
Author(s):  
Supriya Tiwari ◽  
Rüdiger Grote ◽  
Galina Churkina ◽  
Tim Butler
Keyword(s):  
Stomatal Conductance ◽  
Environmental Conditions ◽  
Economic Losses ◽  
Plant Responses ◽  
Damage Scenarios ◽  
Biochemical Processes ◽  
Wide Range ◽  
Defence Responses ◽  
High Concentrations ◽  
The Impact

High concentrations of ozone (O3) can have significant impacts on the health and productivity of agricultural and forest ecosystems, leading to significant economic losses. In order to estimate this impact under a wide range of environmental conditions, the mechanisms of O3 impacts on physiological and biochemical processes have been intensively investigated. This includes the impact on stomatal conductance, the formation of reactive oxygen species and their effects on enzymes and membranes, as well as several induced and constitutive defence responses. This review summarises these processes, discusses their importance for O3 damage scenarios and assesses to which degree this knowledge is currently used in ecosystem models which are applied for impact analyses. We found that even in highly sophisticated models, feedbacks affecting regulation, detoxification capacity and vulnerability are generally not considered. This implies that O3 inflicted alterations in carbon and water balances cannot be sufficiently well described to cover immediate plant responses under changing environmental conditions. Therefore, we suggest conceptual models that link the depicted feedbacks to available process-based descriptions of stomatal conductance, photosynthesis and isoprenoid formation, particularly the linkage to isoprenoid models opens up new options for describing biosphere-atmosphere interactions.

scholarly journals Characterization of simultaneous uptake of xylose and glucose in Caldicellulosiruptor kronotskyensis for optimal hydrogen production

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Thitiwut Vongkampang ◽  
Krishnan Sreenivas ◽  
Jonathan Engvall ◽  
Carl Grey ◽  
Ed W. J. van Niel
Keyword(s):  
Glucose Uptake ◽  
Growth Patterns ◽  
Sugar Uptake ◽  
Uptake System ◽  
Sugar Mixtures ◽  
Xylose Uptake ◽  
Growth Profiles ◽  
High Concentrations ◽  
Xylose Transporter

Abstract Background Caldicellulosiruptor kronotskyensis has gained interest for its ability to grow on various lignocellulosic biomass. The aim of this study was to investigate the growth profiles of C. kronotskyensis in the presence of mixtures of glucose–xylose. Recently, we characterized a diauxic-like pattern for C. saccharolyticus on lignocellulosic sugar mixtures. In this study, we aimed to investigate further whether C. kronotskyensis has adapted to uptake glucose in the disaccharide form (cellobiose) rather than the monosaccharide (glucose). Results Interestingly, growth of C. kronotskyensis on glucose and xylose mixtures did not display diauxic-like growth patterns. Closer investigation revealed that, in contrast to C. saccharolyticus, C. kronotskyensis does not possess a second uptake system for glucose. Both C. saccharolyticus and C. kronotskyensis share the characteristics of preferring xylose over glucose. Growth on xylose was twice as fast (μmax = 0.57 h−1) as on glucose (μmax = 0.28 h−1). A study of the sugar uptake was made with different glucose–xylose ratios to find a kinetic relationship between the two sugars for transport into the cell. High concentrations of glucose inhibited xylose uptake and vice versa. The inhibition constants were estimated to be KI,glu = 0.01 cmol L−1 and KI,xyl = 0.001 cmol L−1, hence glucose uptake was more severely inhibited by xylose uptake. Bioinformatics analysis could not exclude that C. kronotskyensis possesses more than one transporter for glucose. As a next step it was investigated whether glucose uptake by C. kronotskyensis improved in the form of cellobiose. Indeed, cellobiose is taken up faster than glucose; nevertheless, the growth rate on each sugar remained similar. Conclusions C. kronotskyensis possesses a xylose transporter that might take up glucose at an inferior rate even in the absence of xylose. Alternatively, glucose can be taken up in the form of cellobiose, but growth performance is still inferior to growth on xylose. Therefore, we propose that the catabolism of C. kronotskyensis has adapted more strongly to pentose rather than hexose, thereby having obtained a specific survival edge in thermophilic lignocellulosic degradation communities.

PATTERNS OF GROWTH IN HEIGHT AND WEIGHT FROM BIRTH TO EIGHTEEN YEARS OF AGE

PEDIATRICS ◽  
1959 ◽  
Vol 24 (5) ◽  
pp. 904-921
Author(s):  
Robert B. Reed ◽  
Harold C. Stuart
Keyword(s):  
Growth Curves ◽  
Growth Patterns ◽  
Individual Growth ◽  
Growth Spurt ◽  
Adolescent Growth Spurt ◽  
Wide Range ◽  
Basic Facts ◽  
The Individual ◽  
Rates Of Growth ◽  
Mature Size

In this report is displayed the range of variation observed in the growth curves of height and weight in a series of 134 children observed from birth to 18 years. For purposes of simplification the individuals have been classified on the basis of their rates of growth during three successive 6-year intervals. Even in terms of this crude classification several basic facts about individual growth patterns of height and weight are apparent. The wide range of differences between individuals applies not only to facts about size at specific ages but also to the pattern of change followed from age period to age period. The rate of growth during early childhood, i.e. before 6 years of age, is associated with, but not specifically predictive of, size at maturity and timing of the adolescent growth spurt. Individuals with rapid growth before 6 years of age tend to have large mature size and early adolescent growth spurt. It will be the objective of future reports from this research project to determine the manner in which the individual differences in growth demonstrated and classified here are related to aspects of physical development, to environmental influences such as dietary intake and to the level of health of the child.

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