The role of copepod-dominated meiofauna in the mineralization of organic matter in a cold marine mesocosm

Large populations of meiofauna are found in the sand filters of the St. Lawrence mesocosm at the Montreal Biodome. Three 30-day experiments were conducted in heterotrophic microcosms to quantify how populations of micro- and meio-faunal organisms affect mineralization using the apparent mineralization rate (AMR), i.e., nitrate production, as a proxy. Tryptone, mesocosm detritus, and fishmeal were used as organic substrates (C:N ratios 4-8). Harpacticoid copepods dominated the meiofauna in numbers (87%) and biomass (90%). AMR was inversely related to meiofaunal mass and not related to ciliate density. Through grazing, 1 g meiofaunal dry mass·m-2 reduced the AMR of tryptone by 42%, of detritus by 9.4%, and of fishmeal by 2.7%. Particle size affected the effect of meiofauna, whereas the C:N ratio affected the AMR. The scarcity of nematodes, which are known to stimulate mineralization, may explain these results. Copepod-dominated meiofauna decrease nutrient regeneration rates in heterotrophic habitats when C:N ratios are low.

Download Full-text

Role of copepod-dominated meiofauna in the nitrification process of a cold marine mesocosm

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f99-096 ◽

1999 ◽

Vol 56 (9) ◽

pp. 1639-1648 ◽

Cited By ~ 1

Author(s):

Serge Parent ◽

Antoine Morin

Keyword(s):

Ammonia Oxidation ◽

Nitrifying Bacteria ◽

Nitrification Rate ◽

Nitrite Oxidation ◽

Sand Filters ◽

Large Populations ◽

Negative Effect ◽

The Relationship ◽

Positive Effect

Large populations of copepod-dominated meiofauna are found in the sand filters of the St. Lawrence marine mesocosm at the Montreal Biodome. Experiments were conducted in heterotrophic microcosms to quantify how populations of micro- and meiofaunal organisms affect ammonia oxidation (nitrition) and nitrite oxidation (nitration) using apparent nitrition rate (ANiR) and apparent nitration rate (ANaR) as proxies. ANiR and ANaR were not related to ciliate density. Meiofauna had no effect on ANiR, but a significant relationship between ANaR and meiofaunal biomass was observed, which varied with the particulate organic nitrogen (PON) content of the sediment. The relationship was negative at low PON and positive at high PON. These results suggest a direct negative action by predation on nitrifying bacteria and an indirect positive action by reducing competitors through grazing of heterotroph bacteria. The negative effect of 1 g meiofauna·m-2 at low PON (-20% of ANaR0, i.e., ANaR without meiofauna) is much smaller than its positive effect at high PON (+172 to +571% of ANaR0). Copepod-dominated meiofaunal biomasses less than 0.16 g·m-2 increase two to five times the nitrification rate in heterotrophic habitats rich in PON.

Download Full-text

Fibrin Formation: The Role of the Fibrinogen-Fibrin Monomer Complex

Thrombosis and Haemostasis ◽

10.1055/s-0038-1648007 ◽

1976 ◽

Vol 36 (01) ◽

pp. 037-048 ◽

Cited By ~ 49

Author(s):

Eric P. Brass ◽

Walter B. Forman ◽

Robert V. Edwards ◽

Olgierd Lindan

Keyword(s):

Particle Size ◽

Induction Period ◽

Fibrin Clot ◽

Clot Formation ◽

Appreciable Amount ◽

Buffer System ◽

Homeostatic Mechanism ◽

Fibrin Formation ◽

Fibrin Monomer

SummaryThe process of fibrin formation using highly purified fibrinogen and thrombin was studied using laser fluctuation spectroscopy, a method that rapidly determines particle size in a solution. Two periods in fibrin clot formation were noted: an induction period during which no fibrin polymerization occurred and a period of rapid increase in particle size. Direct measurement of fibrin monomer polymerization and fibrinopeptide release showed no evidence of an induction period. These observations were best explained by a kinetic model for fibrin clot formation incorporating a reversible fibrinogen-fibrin monomer complex. In this model, the complex serves as a buffer system during the earliest phase of fibrin formation. This prevents the accumulation of free polymerizable fibrin monomer until an appreciable amount of fibrinogen has reacted with thrombin, at which point the fibrin monomer level rises rapidly and polymerization proceeds. Clinically, the complex may be a homeostatic mechanism preventing pathological clotting during periods of elevated fibrinogen.

Download Full-text

272. Controlling Respirable Quartz Dust in Sand-Blasting: Role of Sand Particle Size and a Dust Suppression Agent

10.3320/1.2765800 ◽

2001 ◽

Author(s):

J. Nelson ◽

S. Soderholm ◽

M. Greskevitch

Keyword(s):

Particle Size ◽

Sand Particle ◽

Dust Suppression ◽

Sand Blasting ◽

Quartz Dust

Download Full-text

Galectin-3 in Heart Failure – Linking Fibrosis, Remodelling and Progression

European Cardiology Review ◽

10.15420/ecr.2010.6.2.33 ◽

2010 ◽

Vol 6 (2) ◽

pp. 33 ◽

Cited By ~ 10

Author(s):

Christopher R deFilippi ◽

G Michael Felker ◽

◽

Keyword(s):

Heart Failure ◽

Ejection Fraction ◽

Risk Stratification ◽

Cardiac Fibrosis ◽

The Elderly ◽

Preserved Ejection Fraction ◽

Heart Failure Patients ◽

Large Populations ◽

Galectin 3

For many with heart failure, including the elderly and those with a preserved ejection fraction, both risk stratification and treatment are challenging. For these large populations and others there is increasing recognition of the role of cardiac fibrosis in the pathophysiology of heart failure. Galectin-3 is a novel biomarker of fibrosis and cardiac remodelling that represents an intriguing link between inflammation and fibrosis. In this article we review the biology of galectin-3, recent clinical research and its application in the management of heart failure patients.

Download Full-text

Faculty Opinions recommendation of The role of the particle size spectrum in estimating POC fluxes from disequilibrium.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1087095.540074 ◽

2007 ◽

Author(s):

Edward Laws

Keyword(s):

Particle Size ◽

Size Spectrum

Download Full-text

Positive Role of Synthesis Method and Hard Template on the Catalytic Performance of SAPO-34 in Methanol to Olefin Reaction.

Combinatorial Chemistry & High Throughput Screening ◽

10.2174/1386207323666200720103321 ◽

2020 ◽

Vol 23 ◽

Author(s):

Sajjad Rimaz ◽

Reza Katal

Keyword(s):

Particle Size ◽

Synthesis Method ◽

Catalytic Performance ◽

Hard Template ◽

Structure Directing Agent ◽

Positive Role ◽

Methanol To Olefin ◽

Dg Method ◽

Synthesis Procedure

: In the present study, SAPO-34 particles were synthesized using hydrothermal (HT) and dry gel (DG) conversion methods in the presence of diethyl amine (DEA) as an organic structure directing agent (SDA). Carbon nanotubes (CNT) were used as hard template in the synthesis procedure to introduce transport pores into the structures of the synthesized samples. The synthesized samples were characterized with different methods to reveal effects of synthesis method and using hard template on their structure and catalytic performance in methanol to olefin reaction (MTO). DG conversion method results in smaller particle size in comparison with hydrothermal method, resulting in enhancing catalytic performance. On the other side, using CNT in the synthesis procedure with DG method results in more reduction in particle size and formation of hierarchical structure which drastically improves catalytic performance.

Download Full-text

Effect of grain size on the vapour phase hydration of monoclinic and triclinic modifications of tricalcium silicate; role of high temperature activation

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19911993 ◽

1991 ◽

Vol 56 (10) ◽

pp. 1993-2008

Author(s):

S. Hanafi ◽

G. M. S. El-Shafei ◽

B. Abd El-Hamid

Keyword(s):

Particle Size ◽

Vapour Phase ◽

Tricalcium Silicate ◽

Active Centers ◽

Thermally Activated ◽

Grain Sizes ◽

Intermediate Size ◽

Surface Active ◽

Temperature Activation

The hydration of tricalcium silicate (C3S) with three grain sizes of monoclinic (M) and triclinic (T) modifications and on their thermally activated samples were investigated by exposure to water vapour at 80°C for 60 days. The products were investigated by XRD, TG and N2 adsorption. The smaller the particle size the greater was the hydration for both dried and activated samples from (M). In the activated samples a hydrate with 2θ values of 38.4°, 44.6° and 48.6° could be identified. Hydration increased with particle size for the unactivated (T) samples but after activation the intermediate size exhibited enhanced hydration. Thermal treatment at 950°C of (T) samples increased the surface active centers on the expense of those in the bulk. Changes produced in surface texture upon activation and/or hydration are discussed.

Download Full-text

Identification of key aerosol types and mixing states in the central Indian Himalayas during the GVAX campaign: the role of particle size in aerosol classification

The Science of The Total Environment ◽

10.1016/j.scitotenv.2020.143188 ◽

2020 ◽

pp. 143188

Author(s):

U.C. Dumka ◽

D.G. Kaskaoutis ◽

N. Mihalopoulos ◽

Rahul Sheoran

Keyword(s):

Particle Size ◽

Aerosol Classification ◽

Mixing States ◽

Aerosol Types ◽

Indian Himalayas

Download Full-text

Investigating the Feasibility of Mefenamic Acid Nanosuspension for Pediatric Delivery: Preparation, Characterization, and Role of Excipients

Processes ◽

10.3390/pr9040574 ◽

2021 ◽

Vol 9 (4) ◽

pp. 574

Author(s):

Nikhat Perween ◽

Sultan Alshehri ◽

T. S. Easwari ◽

Vivek Verma ◽

Md. Faiyazuddin ◽

...

Keyword(s):

Particle Size ◽

Mefenamic Acid ◽

Hydroxypropyl Methylcellulose ◽

Sodium Dodecyl ◽

Aqueous Solubility ◽

Oral Route ◽

Precipitation Method ◽

Antisolvent Precipitation

Molecules with poor aqueous solubility are difficult to formulate using conventional approaches and are associated with many formulation delivery issues. To overcome these obstacles, nanosuspension technology can be one of the promising approaches. Hence, in this study, the feasibility of mefenamic acid (MA) oral nanosuspension was investigated for pediatric delivery by studying the role of excipients and optimizing the techniques. Nanosuspensions of MA were prepared by adopting an antisolvent precipitation method, followed by ultrasonication with varying concentrations of polymers, surfactants, and microfluidics. The prepared nanosuspensions were evaluated for particle size, morphology, and rheological measures. Hydroxypropyl methylcellulose (HPMC) with varying concentrations and different stabilizers including Tween® 80 and sodium dodecyl sulfate (SLS) were used to restrain the particle size growth of the developed nanosuspension. The optimized nanosuspension formula was stable for more than 3 weeks and showed a reduced particle size of 510 nm with a polydispersity index of 0.329. It was observed that the type and ratio of polymer stabilizers were responsive on the particle contour and dimension and stability. We have developed a biologically compatible oral nanoformulation for a first-in-class drug beautifully designed for pediatric delivery that will be progressed toward further in vivo enabling studies. Finally, the nanosuspension could be considered a promising carrier for pediatric delivery of MA through the oral route with enhanced biological impact.

Download Full-text