The resistance to dislodgement ofSargassum muticumgermlings under defined hydrodynamic conditions

1983 ◽  
Vol 63 (1) ◽  
pp. 181-193 ◽  
Author(s):  
Trevor A. Norton
Keyword(s):  
Water Flow ◽  
Brown Seaweed ◽  
Sargassum Muticum ◽  
Flowing Water ◽  
Hydrodynamic Conditions ◽  
Secure Attachment ◽  
Water Motion ◽  
The Mean ◽  
Flow Velocities

The attachment capabilities of a brown seaweed,Sargassum muticum(Yendo) Fensholt were investigated in the laboratory on both smooth and rough substrata and in surging water motion reaching flow velocities of 57 cm s and 90 cm s.Newly released zygotes have no means of adhesion until they develop rhizoids, which can adhere on contact with the substratum. Attachment tenacity, as measured by the germling's ability to withstand dislodgement at a given velocity of water flow, is slight at first, but increases with time. This is not simply a function of time spent in residence on the substratum, for germlings cultured suspension stick very quickly and tenaciously when allowed to settle. Tenacity of adhesion seems to be a reflexion of the amount of mucopolysaccharide adhesive present. This increases gradually during the first few days of the germling's life, regardless of whether it is attached or not.Once secure attachment is achieved it is not weakened even by the death of the germling. A film of bacteria and micro algae on the surface of the substratum is not a requirement for germling adhesion, but its presence enhances the tenacity of adhesion.Smooth substrata are the least favourable for germling survival in flowing water. On rough substrata the ‘peaks’ of the microtopography and surfaces facing into the current are much less favourable than the troughs between the ‘peaks’, or surfaces in the lee of ‘peaks’. Germling survival increases with increasing substratum roughness up to an optimum rugosity at which the mean depth of the depressions on the surface is 420 μm, and the vast majority are deeper than the height of the germlings.

scholarly journals On the Health Benefits vs. Risks of Seaweeds and Their Constituents: The Curious Case of the Polymer Paradigm

Marine Drugs ◽  
2021 ◽  
Vol 19 (3) ◽  
pp. 164
Author(s):  
João Cotas ◽  
Diana Pacheco ◽  
Glacio Souza Araujo ◽  
Ana Valado ◽  
Alan T. Critchley ◽  
...  
Keyword(s):  
Brown Seaweed ◽  
Dry Weight ◽  
Sargassum Muticum ◽  
Human Nutrition ◽  
Health Impacts ◽  
Gracilaria Gracilis ◽  
Red Seaweeds ◽  
Positive Effects ◽  
Negative Impacts ◽  
Biomedical Potential

To exploit the nutraceutical and biomedical potential of selected seaweed-derived polymers in an economically viable way, it is necessary to analyze and understand their quality and yield fluctuations throughout the seasons. In this study, the seasonal polysaccharide yield and respective quality were evaluated in three selected seaweeds, namely the agarophyte Gracilaria gracilis, the carrageenophyte Calliblepharis jubata (both red seaweeds) and the alginophyte Sargassum muticum (brown seaweed). It was found that the agar synthesis of G. gracilis did not significantly differ with the seasons (27.04% seaweed dry weight (DW)). In contrast, the carrageenan content in C. jubata varied seasonally, being synthesized in higher concentrations during the summer (18.73% DW). Meanwhile, the alginate synthesis of S. muticum exhibited a higher concentration (36.88% DW) during the winter. Therefore, there is a need to assess the threshold at which seaweed-derived polymers may have positive effects or negative impacts on human nutrition. Furthermore, this study highlights the three polymers, along with their known thresholds, at which they can have positive and/or negative health impacts. Such knowledge is key to recognizing the paradigm governing their successful deployment and related beneficial applications in humans.

scholarly journals OP0147 MEASUREMENT OF FLOW VELOCITIES OF THE CENTRAL RETINAL ARTERY IN PATIENTS WITH GIANT CELL ARTERITIS WITH VISUAL SYMPTOMS AND CONTROLS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 93.2-94
Author(s):  
L. C. Burg ◽  
P. Brossart ◽  
K. I. Reinking ◽  
R. P. Finger ◽  
C. Behning ◽  
...  
Keyword(s):  
Giant Cell Arteritis ◽  
Giant Cell ◽  
Resistance Index ◽  
Visual Field Loss ◽  
Central Retinal Artery ◽  
Control Group ◽  
Visual Symptoms ◽  
Retinal Artery ◽  
The Mean ◽  
Flow Velocities

Background:Giant cell arteritis (GCA) is the most common form of systemic vasculitis in patients aged 50 years and older.1Visual symptoms such as amaurosis, diplopia, temporary or permanent visual field loss secondary to optic nerve ischemia are common manifestations.2The value of vascular ultrasound of extra-ocular vessels in diagnosing GCA is well established.3However, the role of transocular ultrasound of the central retinal artery in GCA patients has not yet been established.Objectives:To identify changes in flow velocities of the central retinal artery in GCA patients with visual symptoms and controls with transocular high resolution ultrasound.Methods:Prospective analysis of GCA patients with visual symptoms and controls. Ultrasound of the central retinal artery was performed in 18 newly diagnosed consecutive GCA patients with visual symptoms (GCA-group) and 25 controls without ocular pathology. Visual symptoms included amaurosis, diplopia and temporary or permanent visual field loss. For each eye, peak systolic values (PS) and end diastolic values (ED) were recorded. Furthermore, the resistance index of each central retinal artery was measured.Results:Twenty-one of 36 eyes of 18 GCA patients were affected. Therefore 21 central retinal were measured. The control group consisted of 50 central retinal arteries of 25 eye-healthy individuals. The mean age and gender distribution of the GCA-group were 75.6 years (SD± 8.1) with eight females (44 %) and 67 years (SD± 8.9) with twelve females (48%) in the control group. The mean flow velocity of the central retinal artery was PS 12.2 cm/s (SD± 3.5) and ED 3.7 cm/s (SD± 1.2) in the GCA group and PS 14.4 cm/s (SD± 3.2) and ED 5.1 cm/s (SD± 1.6) in the control group. The mean RI was 0.9 (SD± 0.3) in the GCA group and 0.8 (SD± 0.3) in the control group. Mean reduction in flow velocity in the GCA-group was PS 2.1 cm/s (p= 0.039) and ED 1.4 (p= 0.0004) cm/s, while the RI was increased by 0.14 (p= 0.077). The results for PS and ED measurements were statistically significant, while the results for RI were not significant.Conclusion:In GCA patients with ocular symptoms, a reduction of flow velocities of the central retinal artery compared to the eye-healthy control group was found. Results for PS and ED were significant. There seems to be a trend for decreased flow velocities in coexistence with visual symptoms in patients with GCA.References:[1]Warrington KJ, Matteson EL. Management guidelines and outcome measures in giant cell arteritis (GCA). Clin Exp Rheumatol 2007;25:137–41.[2]Chean CS, Prior JA, Helliwell T, et al. Characteristics of patients with giant cell arteritis who experience visual symptoms. Rheumatol Int 2019;39:1789–96.[3]Dejaco C, Ramiro S, Duftner C, et al. EULAR recommendations for the use of imaging in large vessel vasculitis in clinical practice. Ann Rheum Dis 2018;77:636–43Figure 1.Transocular ultrasound of an affected eye in giant cell arteritis with reduced flow velocities and increased resistance index.Disclosure of Interests:None declared

scholarly journals Summer shifts of bacterial communities associated with the invasive brown seaweed Sargassum muticum are location and tissue dependent

PLoS ONE ◽  
2018 ◽  
Vol 13 (12) ◽  
pp. e0206734 ◽  
Author(s):  
Alexandra Serebryakova ◽  
Tania Aires ◽  
Frédérique Viard ◽  
Ester A. Serrão ◽  
Aschwin H. Engelen
Keyword(s):  
Bacterial Communities ◽  
Brown Seaweed ◽  
Sargassum Muticum

scholarly journals Normal values of cerebral blood flow velocities in neonates

2010 ◽  
Vol 138 (3-4) ◽  
pp. 186-191 ◽  
Author(s):  
Brankica Vasiljevic ◽  
Miroslava Gojnic ◽  
Svjetlana Maglajlic-Djukic ◽  
Olga Antonovic
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Normal Values ◽  
Color Doppler ◽  
Ductus Arteriosus ◽  
Resistance Index ◽  
Severe Hypotension ◽  
The Mean ◽  
Blood Flow Velocities ◽  
Flow Velocities

Introduction. There was used color Doppler ultrasonography (cD-USI), allowing simultaneous examination of parenchymal and vascular cerebral structures. The evaluation of blood flow velocities in cerebral arteries is important in the assessment of cerebral circulation in hypoxic-ischaemic and haemorrhagic brain damage in neonates. Objective. The aim of this study was to estimate normal values of cerebral blood flow velocities (CBFV) and Doppler indices - pulsatility index (PI) and resistance index (RI) - in the anterior cerebral artery (ACA) during the first days of life in infants. Methods. CBFV, PI and RI were obtained during the first week of life with cD-US in 70 infants divided in four groups of gestational age (GA): ?28 gestational weeks (GW); 29-32 GW; 33-36 GW; and ?37 GW. Infants with congenital malformations, severe perinatal asphyxia, cerebral haemorrhagic lesion, DAP or severe hypotension were excluded. Results. The mean GA of infants was 34.5?5.5 GW (range 26-40 GW) and the mean birth weight (BW) was 2540?950 g (range 750-4000 g). In the 1st group of 10 infants, ?28 GW, the mean BW was 950?110 g and values of RI were 0.59?0.10 and PI 1.06?0.080. In the 2nd group of 20 infants, 29-32 GW, the mean BW was 1350?290 g and values of RI were 0.60?0.10 and PI 1.10?0.15. In the 3rd group of 20 infants, 33-36 GW, the mean BW was 1950?750 g and values of RI were 0.63?0.08 and PI 1.15?0.30. In the 4th group of 20 infants, ?37 GW, the mean BW was 3540?950 g and values of RI were 0.65?0.05 and PI 1.18?0.35. Conclusion. Values of CBFV progressively increase with GA and BW due to progressive increase of cardiac output, blood pressure and closing of ductus arteriosus. Values of RI and PI gradually increase with GA and BW as a result of progressive maturation and opening of vascular cerebral bed with a reduction of the cerebrovascular resistance.

scholarly journals Enhancing Methane Production from Spring-Harvested Sargassum muticum

2021 ◽  
pp. 117-123
Author(s):  
Supattra Maneein ◽  
John J. Milledge ◽  
Birthe V. Nielsen
Keyword(s):  
Anaerobic Digestion ◽  
Pharmaceutical Industry ◽  
Brown Seaweed ◽  
Sargassum Muticum ◽  
Biofuel Production ◽  
Biochemical Methane Potential ◽  
Seaweed Species ◽  
Invasive Seaweed ◽  
Methane Potential ◽  
Aqueous Meoh

AbstractSargassum muticum is a brown seaweed which is invasive to Europe and currently treated as waste. The use of S. muticum for biofuel production by anaerobic digestion (AD) is limited by low methane (CH4) yields. This study compares the biochemical methane potential (BMP) of S. muticum treated in three different approaches: aqueous methanol (70% MeOH) treated, washed, and untreated. Aqueous MeOH treatment of spring-harvested S. muticum was found to increase CH4 production potential by almost 50% relative to the untreated biomass. The MeOH treatment possibly extracts AD inhibitors which could be high-value compounds for use in the pharmaceutical industry, showing potential for the development of a biorefinery approach; ultimately exploiting this invasive seaweed species.

scholarly journals Stability of Sheet Water Flow Under a Glacier

1983 ◽  
Vol 29 (103) ◽  
pp. 374-382 ◽  
Author(s):  
J. Weertman ◽  
G. E. Birchfield
Keyword(s):  
Shear Stress ◽  
Water Flow ◽  
Sheet Thickness ◽  
The Other ◽  
Flowing Water ◽  
Ice Melting ◽  
Geothermal Heat ◽  
Melt Water ◽  
Primary Origin ◽  
Basal Shear

AbstractWalder recently analyzed the initial instability of water flow in a sheet under a glacier that is produced by greater heat production in the flowing water and thus the larger rate of ice melting where a perturbation has increased the water sheet thickness. We have looked at the problem from the other presumed final state. We assume that instabilities have finally caused all the water to flow in channels (R-channels) at the bed. We investigated whether these channels can collect enough of the water that is produced by the geothermal heat and the heat sliding to remain in existence. When a basal shear stress is present, the distance out to which a channel can collect water is not that much greater than the channel radius itself. It is concluded that it is not likely for the channel to be able to collect appreciable amounts of water that is produced at the bed. Hence despite the indication that an instability initially might grow in a water sheet, this instability either cannot develop to the point when the water flow is primarily in channels or else the water flow alternates cyclically between a state primarily of sheet flow and a state of channel flow. It would appear that the channels that do exist under a glacier have their primary origin in the melt water from the upper surface that pours down moulins and thus is already channelized by the time it reaches the bed.

Solute movement through undisturbed calcareous and dry region soils under differing water flow velocities 

2021 ◽  
Author(s):  
Selen Deviren Saygin ◽  
Hasan Sabri Ozturk ◽  
Ezgi Izci ◽  
Manoj Menon ◽  
Sina Maghami Nick ◽  
...  
Keyword(s):  
Water Quality ◽  
Ion Exchange ◽  
Water Flow ◽  
Irrigation Water ◽  
Colloidal Particles ◽  
Tap Water ◽  
Water Application ◽  
Water Flow Velocity ◽  
Sodic Water ◽  
Flow Velocities

<p>The use of low-quality irrigation water in arid regions ensures the reconstruction of diverse physical and chemical dynamics in the soil profile. The objective of this study was to examine the efficacy of two water flow velocities of tap and sodic water for characterizing ion exchange of colloidal particles. Undisturbed samples were taken into the plexiglas columns with 40 cm in height and 6.9 cm in diameter from the dry area of Konya, Turkey. Two different water sources with varying qualities, tap water and poor quality sodic water (ESP≈20, obtained by preparing solution from analytically pure NaHCO<sub>3</sub>), were applied to the top of the columns as leaching water in two water flow velocities; close to saturated hydraulic conductivity (Ks) (fast, saturated condition) and unsaturated condition (slow). The number of the columns with duplicated experiments was 8. In each leaching, a quarter pore volume (350 ml) of water was regularly applied and leachates were collected from the outlet of columns. The water flux in the soil column decreased faster in the fast leaching application than in slow leaching as the sodic irrigation water was applied. This shows to destructive effect of Na+ on inner surface of water flow channels in the soil. Gradual increases for the pH of the leachates in both water quality and velocity experiments were detected. The EC of the leachates dropped very fast at the beginning of leaching in both water quality applications, and then, became steady. No effect of tap water treatment on Ca<sup>+2</sup> contents of the leachates was observed. However, sharp decreases in Ca<sup>+2 </sup>concentration were detected at the beginning of sodic water application, and then remained constant. All sodic water applications caused an increase in Na+ concentration of leachates till the end of treatments. In slow leaching applications, the increase in Na concentration in the leachates was slower compared to those of the fast leaching. While Ca<sup>+2</sup> concentrations in the leachates remained constant with tap water applications, although the soils are calcareous. Ca<sup>+2</sup> was transported remarkable high at the beginning of the sodic water application. As the leaching progressed, transport of Ca<sup>+2</sup> from the soil continued constantly due to the Na-Ca exchange processes. The effects of different leaching treatments were clearly observed from the pH-EC, Ca<sup>+2</sup> and Na<sup>+</sup>transports. Consequently, sodic water application caused significant changes in the pH values of the soils with the effect of time, and this effect was expressively marked from the changes in the salt and sodium contents of the soils.</p><p>Keywords: flux, ion exchange, leaching, saturated and unsaturated leaching, solute transport, water flow velocity</p><p>Acknowledgement: This work was supported by the Scientific and Technological Research Council of Turkey [Project number: TUBİTAK-118Y343].</p>

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