Laminaria Digitata Research Articles

Numeric modelling of innovative semi‐rigid connections under cyclic loading

AbstractThis paper presents the analytical results of six steel bolted T‐connection models and four steel bolted beam‐to‐column connection models with top and seat angles. This study was undertaken to analyse the influence of bolted T‐connections instead of welded connections and the influence of angles with and without stiffeners on the behaviour of the beam‐to‐column connections under hysteretic loading. The aim was to compare the energy dissipation of different connections with each other. The energy dissipation characteristics are obtained from the main characteristics of moment‐rotation hysteresis curves. This study shows that the energy dissipation decreased by about 2–29 % and 2–13 % for bolted T‐connection and top‐and‐seat‐angle connection models respectively after switching from one cycle to another in five hysteretic loadings.

Experimental study on composite connection with double lipped C- Sections

The application of Cold-formed steel (CFS) is getting popular in several countries, and this indicates that a good potential of using lightweight materials as an alternative solution to conventional steel. However, there is still a lack of information about joint behavior, particularly composite connections integrated with CFS. This paper presents an isolated joint test of composite joints consisting of concrete slab 100 mm thickness, double lipped channel section used for beam and column, connected by hot-rolled steel gusset plates and bolts. The weakness of the thin plate behavior in the compression zone was reduced by installing the angle stiffener on the web column. Two specimens with the same configuration but with and without seat angle were tested. The experiment results revealed that by the use of seat angle, the moment resistance and stiffness of joints increased with the ratio 1.06 and 1.19, respectively.

Study to control the cab shaking of vibratory rollers using the horizontal auxiliary damping mount

To control the cab shaking of the vibratory roller, an auxiliary damping mount (ADM) used for the cab isolation system in horizontal direction is proposed. Based on the off-road vibratory roller dynamic model under the conditions of the vehicle moving and compacting, the damping characteristic and installation position of the ADM for reducing vibration of the cab are respectively analyzed. The weighted root-mean-square (RMS) of acceleration responses of the vertical driver’s seat and pitching cab angle are chosen as the objective functions. The research results show the cab shaking is greatly reduced by using the ADM in comparison without ADM. Additionally, the drive’s seat vibration is also significantly decreased under both the compacting and moving conditions of the vibratory roller.

Composition analysis and minimal treatments to solubilize polysaccharides from the brown seaweed Laminaria digitata for microbial growth of thermophiles

Brown macroalgae (Phaeophyta) hold high potential as feedstock for biorefineries due to high biomass productivity and carbohydrate content. They are, however, a challenging, unconventional feedstock for microbial refining and several processing problems need to be solved to make them a viable option. Pre-treatment is necessary to enhance accessibility and solubility of the biomass components but should be minimal and mild to assure sustainable and cost-effective processing. Here, two routes to pre-treatLaminaria digitata to release polysaccharides were investigated: hot water pre-treatment by autoclaving (121 °C, 20 min or 60 min) and a two-step extraction with mild acid (0.1 M HCl) followed by alkaline treatment. Hot water pre-treatment resulted in partial extraction of a mixture of polysaccharides consisting of alginate, fucoidan and laminarin. After mild acid pre-treatment, alginate was found in the remaining insoluble residues and was extracted in a second step via alkaline treatment using Na2CO3 (0.15 M) at 80 °C and CaCl2 (10%) for the precipitation. In addition to carbohydrates, a fraction of other components such as proteins, phenolic compounds, minerals and trace elements was detected in the extracts. Cultivation of the thermophilic bacterial strains Rhodothermus marinus DSM 16675 and Bacillus methanolicus MGA3 (ATCC 53907) in media supplemented with the respective extracts resulted in growth of both strains, indicating that they were able to utilize the available carbon source for growth. R. marinus displayed the highest cell density in the medium containing the extract from acid pre-treatment, whereas B. methanolicus growth was highest with the extract from hot water pre-treatment.

Evaluation of seaweeds from marine waters in Northwestern Europe for application in animal nutrition

The increasing demand for animal protein by the growing world population intensifies the exploration of novel feed sources. This study evaluated the nutritional value of six intact seaweed species (i.e. the brown species Saccharina latissima, Laminaria digitata, and Ascophyllum nodossum, the red species Palmaria palmata, and Chondrus crispus and green species Ulva lactuca), collected from the coast of Ireland, Scotland and France as an ingredient for animal feed. The nutrient composition, in vitro digestibility, and in vitro gas production simulating rumen fermentation, were determined.The nutrient contents (g/kg dry matter), both between and within species, were highly variable, ranging from 45–248 for crude protein, 351–691 for non-starch polysaccharides, and 173–445 for ash. Overall, the brown seaweeds had the highest non-starch polysaccharides content, whereas samples of the red and green seaweeds had an amino acid content up to 265 g/kg dry matter. All samples had a substantial non-protein nitrogen fraction, varying from 0.12–0.29 of nitrogen. The fibre fractions of brown seaweeds showed different properties than land-based plants, as illustrated by a lower analysed neutral detergent fibre than acid detergent fibre content. The ileal organic matter and nitrogen digestibility, as well as the total tract organic matter digestibility (mean digestibility coefficients: 0.81, 0.89 and 0.88, respectively) were lower for all seaweeds compared to soybean meal (digestibility coefficients: 0.84, 0.98 and 0.97, respectively). S. latissima, L digitata, P. palmata and U. lactuca had a higher maximum gas production than alfalfa, but lower than sugar beet pulp. Based on the protein content and amino acid-pattern, intact P. palmata and U. lactuca would be a valuable protein source for farm animals, with the high non-starch polysaccharides and non-protein nitrogen contents and a low in vitro digestibility potentially limiting their use as a feed ingredient for monogastric species. The fermentability of L. digitata, S. latissima and P. palmata indicate that these intact seaweeds may have a higher nutritional value in ruminants. The high ash content in all seaweed species hampers the use of intact seaweed for both ruminants and monogastrics. Extraction of protein and other favourable components, while reducing the ash content, seems an important step towards seaweed inclusion in animal diets. Further identification and characterisation of seaweed polysaccharides is required to understand and improve the digestibility of seaweed fractions.

Theoretical and experimental behaviour of a hybrid semi-rigid glulam beam-to-column connection with top and seat angles

This article proposes to use the bolted top and seat angles to provide excellent moment resistance and high energy dissipation capacity for glulam beam-to-column connection. Angles are anchored on the glulam beam using the glued-in steel plate technology and connected to the column by anchorage bolts. A theoretical model is presented in this article to evaluate the moment-resistant properties of the connection based on the component method. To validate the accuracy of the theoretical model, several hybrid connections are tested under monotonic and reversed cyclic load. The test results showed that the proposed hybrid connection has a high rotational stiffness and excellent moment resistance. The theoretical results are also consistent with those of the experimental model.

Effect of seat tube angle and crank arm length on metabolic and neuromuscular responses and lower extremity joint kinematics during pedaling with a relatively lower seat height.

The effects of the seat tube angle and crank arm length on metabolic responses, neuromuscular activation, and lower extremity joint kinematics were investigated during bicycling with a relatively lower seat height usually used for daily life. Eleven young males performed bicycling on ergometer with various seat tube angles (60°, 65°, and 70°) and crank arm lengths (127, 140, 152, and 165mm). Oxygen consumption was measured with electromyography of the knee extensor muscle, and hip, knee, and ankle joint angles. The seat height was set as the shorter than subject's trochanter height, because this study simulates pedaling a bicycle in daily life on public roads. Significantly higher oxygen consumption was noted with a 70° of seat tube angle on comparison with a 65° of seat tube angle (p < 0.05). There were no significant effects of the crank arm length on oxygen consumption (p > 0.05). From these results, the present study suggests that a shallower seat angle could help to decrease the physiological burden during bicycling with a relatively lower seat height.

Investigating the impact of inoculum source on anaerobic digestion of various species of marine macroalgae

This study investigated the intrinsic biodegradation potential of marine organic sediment for effective biogas production from various species of marine macroalgae and non-marine biomass. Biogas production potential tests were carried out on three species of seaweed harvested from the west coasts of Scotland, Laminaria digitata, Fucus serratus, and Saccharina latissima, and on a non-marine cellulose biomass seeded with uncultivated and unadapted anoxic marine sediments. As a comparison, the same experiments were repeated using the same substrates but seeded with active mesophilic anaerobically digested sewage sludge. For the cultures seeded with anoxic marine sediments, the highest methane yield was observed in both L. digitata and S. latissima cultures while F. serratus and cellulose, cultures performed relatively poorly. For those seeded with digested sludge, all cultures performed relatively well, except F. serratus. These results show that marine sediments can be effective inoculum for seaweeds digestion. Phylogenetic analyses of the methanogenic community in both sources of inoculum showed that the methanogen community within the sediment and sludge seeded cultures were different. Each culture was dominated by methanogenic populations suitable for the utilisation of the specific biomass derivatives and environmental conditions. For instance, members of the genus Methanosaeta which, dominated sludge seeded cultures were not detected in the sediment seeded cultures. A similar occurrence was observed for the genus Methanofollis which was only detected in the sediment seeded cultures. Hence, in areas where seaweed forms part of a co-digestion with non-marine biomass, start-up using a mixture of anoxic marine sediments and digested wastewater sludge has the potential to provide greater process stability and robustness than using either as sole inoculum.

Marine macroalgae as food for earthworms: growth and selection experiments across ecotypes

Historically, subsistence farmers around the Atlantic coast of NW Europe utilized marine algae as a fertilizer in agroecosystems, a practice that continued in small areas and is now considered to have real potential for re-establishing sustainable food production systems on marginal soils. Earthworms form a significant component of soil fauna, and their ecosystem services are well-documented. Therefore, palatability of marine organic amendments to faunal detritivores of terrestrial systems is of interest. This work aimed to assess the potential for growth of Aporrectodea caliginosa, Lumbricus rubellus and Aporrectodea longa fed with two common macroalgae (seaweeds), Laminaria digitata and Fucus serratus. In addition, choice chambers were constructed to permit earthworm selection of these macroalgae with more conventional organic materials, horse manure (HM) and birch leaves (BL). Over a period of 2 months, earthworm species showed significantly greater mass gain with conventional food (p < 0.05). Laminaria outperformed Fucus, which in turn was superior to soil alone. Similarly, when given a choice, a significant preference (p < 0.001) was shown for the more nitrogen-rich HM and BL over the seaweeds. No removal was recorded for A. caliginosa when offered seaweeds only. By contrast, L. rubellus and A. longa showed significant preferences (p < 0.001) for Laminaria over Fucus and fresh material over degraded. These results underline an interest to profit from natural resources (seaweeds) to maintain or improve soil biological quality in marginal coastal areas.

A case of small intestinal perforation due to sea tangle roll impaction revealed during laparoscopic surgery for a ruptured ovarian tumor

A case of small intestinal perforation due to sea tangle roll impaction revealed during laparoscopic surgery for a ruptured ovarian tumor

Performance of PID-Fuzzy control for cab isolation mounts of soil compactors

To improve the soil compactor ride comfort, a combined control method of Fuzzy and PID control is proposed to control the cab isolation system of soil compactor based on the non-linear vehicle dynamic model. The vibration excitation sources are concerned by the vibrator drum and elastoplastic soil (EPS) interactions in the compression process. The power-spectral-density (PSD) and weighted root-mean-square (RMS) of acceleration responses of both the vertical driver’s seat and pitching cab angle are chosen as the objective functions. The research results show that both the PSD and weighted RMS values of the vertical driver’s seat and pitching cab angle are significantly reduced by using the PID-Fuzzy control under various EPSs in the low-frequency region, especially on the EPS with high-density.

Initial evaluation of six different brown algae species as source for crude bioactive fucoidans

The fucose-containing sulfated polysaccharides (syn. fucoidans) from brown seaweeds exhibit multiple biological activities. The aim of the present study was to evaluate the suitability of crude fucoidans from six different brown algal species for further research and development. For this, fucoidans were extracted from Fucus vesiculosus (F.v.), F. serratus (F.s.), F. evanescens (F.e.), Dictyosiphon foeniculaceus (D.f.), Laminaria digitata (L.d.), and Saccharina latissima (S.l.) and compared concerning their yields, their basic characteristics, degree of sulfation (DS), molecular mass, monosaccharide composition, their contents of polyphenols, laminarin and protein as well as their radical-scavenging capacity, three exemplary bioactivities and their fluorescence intensity (FI) increasing effect on the sulfated glycan sensor Polymer-H. The activities positively correlated with the DS, fucose content and the FI of Polymer H, whereas the antioxidant capacity correlated with the coextracted polyphenols. The best predictive power for the activities showed to have the combination of FI of Polymer-H and DS, which can thus be used for an initial screening of algae extracts. D.f. turned out to be unsuitable as fucoidan source, as the extract had only a low DS (0.14) and fucose content (38.7%) as well as the weakest bioactivities. The fucoidans from S.l. and F.e., which had the fucose content, highest DS, purity and yield, exhibited the best activities and thus proved to be the fucoidans most suitable for further investigations.

Improving biohydrogen and biomethane co-production via two-stage dark fermentation and anaerobic digestion of the pretreated seaweed Laminaria digitata

Abstract The marine macro-alga Laminaria digitata is an abundant brown seaweed, which may be used as a feedstock for gaseous biofuel production via sequential dark fermentation and anaerobic digestion. Various methods, including hydrothermal pretreatment (HTP), hydrothermal dilute acid pretreatment (HTDAP), enzymolysis, and combinations thereof, were employed to depolymerize L. digitata and assess the effects on biohydrogen and biomethane yields. Scanning electron microscopic images revealed that the intact and smooth structure of the seaweed was severely damaged; some micro-pores and debris were generated after HTP (140 °C for 20 min), whilst the undegraded components remained as filamentous structures. The complex carbohydrate polymers in L. digitata constrained the catalytic effects of glucoamylase, leading to limited increase in the yield of carbohydrate monomers. With the aid of H2SO4 (1 v/v%) in HTP, depolymerization of biomass and its further conversion to carbohydrate monomers were significantly improved. The yield of total carbohydrate monomers after HTDAP (0.564 g/gVS) was 3.5-fold that in raw biomass; this led to an increase of 60.8% in biohydrogen yield (57.4 mL/gVS) in the first-stage dark fermentation. However, the generation of byproducts such as hydroxymethylfurfural under such harsh conditions impaired the second-stage anaerobic digestion of hydrogenogenic effluent, resulting in a 25.9% decrease in biomethane yield. HTP was considered the optimum pretreatment improving energy conversion efficiency from seaweed to gaseous biofuels by 26.7% as compared to that of the unpretreated L. digitata.

In-Vitro Antioxidant Properties of Lipophilic Antioxidant Compounds from 3 Brown Seaweed.

Lipophilic compounds of seaweed have been linked to their potential bioactivity. Low polarity solvents such as chloroform, diethyl ether, n-hexane and their various combinations were used to extract the lipophilic antioxidants from brown seaweed namely Himanthalia elongata, Laminaria saccharina and Laminaria digitata. An equal-volume mixture of chloroform, diethyl ether and n-hexane (Mix 4) gave the highest total phenol (52.7 ± 1.93 to 180.2 ± 1.84 mg gallic acid equivalents/g), flavonoid (31.9 ± 2.65 to 131.3 ± 4.51 mg quercetin equivalents/g), carotenoid (2.19 ± 1.37 to 3.15 ± 0.91 μg/g) and chlorophyll content (2.88 ± 1.08 to 3.86 ± 1.22 μg/g) in the tested seaweeds. The extracts were screened for their potential antioxidant capacity and the extracts obtained from the selected solvents system exhibited the highest radical scavenging capacity against 2,2′-diphenly-1-picrylhydrazyl radical (EC50 98.3 ± 2.78 to 298.8 ± 5.81 mg/L) and metal ions (EC50 228.6 ± 3.51 to 532.4 ± 6.03 mg/L). Similarly, the same extract showed the highest ferric reducing antioxidant power (8.3 ± 0.23 to 26.3 ± 0.30 mg trolox equivalents/g) in all the seaweeds. Rapid characterization of the active extracts by liquid chromatography coupled with photodiode array detector and electrospray ionization tandem mass spectrometry (LC-PDA–ESI-MS/MS) identified cyanidin-3-O-glucoside, fucoxanthin, violaxanthin, β-carotene, chlorophyll a derivatives and chlorophyll b derivatives in the tested seaweed. The study demonstrated the use of tested brown seaweed as potential species to be considered for future applications in medicine, cosmetics and as nutritional food supplement.

The antihyperlipidemic effect of alginate-free residue from sea tangle in hyperlipidemic rats

BackgroundIn order to assess the high value-added use of the alginate-free residue of sea tangle, an animal study was performed to evaluate the functional activities and key compounds present. In the animal study, sea tangle and the alginate-free residue demonstrated good anti-hyperlipidemic and anti-arteriosclerotic abilities.ResultsThe functional compounds in the alginate-free residue of the sea tangle were effectively extracted by supercritical fluid extraction (SFE). The optimum extraction temperature and pressure were 40 °C and 6500 psi (M1) in the SFE, a better method in comparison to the conditions of 70 °C and 4500 psi (M2), respectively. The anti-atherosclerotic effects of the alginate-free residue of sea tangle (M1, M2) were investigated in Sprague-Dawley rats treated with poloxamer 407, Triton WR 1339, corn oil, and a high-fat diet. The M1 fraction reduced the serum lipid levels with greater efficacy than the M2 fraction. In the hyperlipidemic rats, treatment with M1 decreased the serum triglyceride (TG), total cholesterol (TC), and low-density lipoprotein-cholesterol (LDL-C) levels when compared to the levels in normal rats.ConclusionOur results demonstrated that the alginate-free residue of sea tangle reduces serum TC, TG, and LDL-C. These results suggest that the alginate-free residue of sea tangle contains physiologically active components, such as fucosterol, that may exert beneficial effects in the prevention of atherosclerosis.

Influence of waves and currents on the growth rate of the kelp Laminaria digitata (Phaeophyceae).

The kelp Laminaria digitata growing in the low intertidal region along energetic coastlines are exposed to a range of hydrodynamic environments. Macroalgae in the intertidal zone can experience both waves and currents independently, but it is unknown how they influence growth rate. Relative growth rate of the meristematic region and the entire blade of L.digitata were measured to assess the influence of wave and current motion from three hydrodynamic environments: low current and low wave (LCLW), high current and low wave (HCLW), and high wave and low current (HWLC). Alongside hydrodynamic data, seawater nutrient concentrations and temperature were also collected and analyzed. Results suggest that differences in L.digitata relative growth rates were not attributed to the seawater nutrient concentrations or temperature, but attributed to the hydrodynamic environments. At the high current condition, kelp growth rate of the meristematic region was enhanced by 45% compared to the high wave condition. When including the entire blade growth rate, an average increase of 25% was observed between the high current and high wave condition. Potentially, the division in growth rate observed between the wave and current motion is related to the frequency and magnitude at which the hydrodynamic forces act. These findings highlight the complexity ofthe hydrodynamic environment and that forces associated with waves and currents may have a significant role on the productivity of kelp.

Temperature mediates the outcome of species interactions in early life-history stages of two sympatric kelp species

Ocean warming can mediate species interactions and provoke changes in community structure worldwide. Species interactions vary along environmental gradients and life-history stages and increasing temperatures may change competitive dominance between species. Kelps, being marine foundation species, have a complex heteromorphic life cycle, with the early developmental stages being a bottleneck for successful establishment of the adult population. Here, we investigated how temperature influences interactions in early life-history stages of two kelp species with different thermal affinities (Alaria esculenta and Laminaria digitata from Spitsbergen) by cultivating them in mono- and co-culture and different temperatures. Irrespectively of cultivation treatment, spore germination, gametogenesis, and sporophyte development of both species were mostly positively stimulated by a temperature increase from mean ambient summer temperatures (4–5 °C) to a global warming scenario for the Arctic future (9–10 °C) but not at 15 °C which is the southern temperature limit of A. esculenta. At 15 °C gametogenesis and sporophyte formation of A. esculenta were greatly inhibited in monoculture but not so in L. digitata. On the other hand at 5 °C and 10 °C, gametogenesis and sporophyte growth were generally faster in A. esculenta than in L. digitata, leading to a competitive advantage of A. esculenta over L. digitata in the co-cultivation treatments. The interactive effects of co-cultivation and temperature were evident, where development of A. esculenta was accelerated in the presence of L. digitata at 9 °C but not at 4 °C. Although the mechanisms triggering interspecific interactions were not determined in this study, future global warming was found to give competitive advantage of A. esculenta over L. digitata, which could affect community structure and dominance in coastal environments.

Development of high alginate comprised hydrogels for removal of Pb(II) ions

Natural polymers have been used for the development of innovative hydrogels in order to improve their properties, principally, their swelling capacity. Herein, an alginate-acrylamide hydrogel was developed by employing a high proportion of alginate via a free-radical polymerization method. Water soluble alginate was extracted from Laminaria digitata and used for the development of alginate hydrogels in order to obtain superior hydrogels. Water adsorption capacity (swelling) and diffusion kinetics performance of the hydrogels were investigated. The hydrogel containing a high amount of alginate had the highest swelling capacity (109.3 g/g) and diffusion coefficient (3.5116 cm2 s−1), which has high water absorption capacity. This hydrogel exhibited super case II diffusion and other hydrogels showed anomalous diffusion water transport phenomena. Additionally, the hydrogel with high alginate content, showed high adsorption of Pb(II) ions. Owing to their swelling and adsorption capacity of Pb(II) ions, this hydrogel could serve as a strong absorbent material in water purification and agricultural applications.

Intra-Annual Variability in Responses of a Canopy Forming Kelp to Cumulative Low Tide Heat Stress: Implications for Populations at the Trailing Range Edge.

Anthropogenic climate change is driving the redistribution of species at a global scale. For marine species, populations at trailing edges often live very close to their upper thermal limits and, as such, poleward range contractions are one of the most pervasive effects of ongoing and predicted warming. However, the mechanics of processes driving such contractions are poorly understood. Here, we examined the response of the habitat forming kelp, Laminaria digitata, to realistic terrestrial heatwave simulations akin to those experienced by intertidal populations persisting at the trailing range edge in the northeast Atlantic (SW England). We conducted experiments in both spring and autumn to determine temporal variability in the effects of heatwaves. In spring, heatwave scenarios caused minimal stress to L.digitata but in autumn all scenarios tested resulted in tissue being nonviable by the end of each assay. The effects of heatwave scenarios were only apparent after consecutive exposures, indicating erosion ofresilience over time. Monthly field surveys corroborated experimental evidence as the prevalence of bleaching (an indication of physiological stress and tissue damage) in natural populations was greatest in autumn and early winter. Overall, our data showed that L.digitata populations in SW England persist close to their upper physiological limits for emersion stress in autumn. As the intensity of extreme warming events is likely to increase with anthropogenic climate change, thermal conditions experienced during periods of emersion will soon exceed physiological thresholds and will likely induce widespread mortality and consequent changes at the population level.

Sea tangle (Laminaria japonica) supplementation on meat quality of Korean native black goat.

The supplementation effects of sea tangle powders were determined for the meat quality in Korean native black goats. A total 90 castrated male black goats at 3-month age were divided into 3 dietary treatment groups: control (basal diet + mineral block), T1 (0.3% sea tangle feeding with the basal diet), T2 (0.9% sea tangle feeding with the basal diet). At 9-months feeding, 10 goats per treatment group were slaughtered, and the longissimus dorsi muscle samples were vacuum-packed, and subsequently analyzed for physicochemical evaluations. Analysis revealed decrease in the shear force and TBARS values of meat in the sea tangle dietary groups (p < 0.05). The T2 group exhibited increased levels of unsaturated fatty acids such as C16:1, C18:1, C18:2, and C20:4 (p < 0.05). The content of free amino acids with desirable taste such as aspartic acid, glutamic acid, glycine, histidine, and serine were higher in T2, whereas alanine content was higher in both sea tangle dietary groups, as compared to control (p < 0.05). These data indicate that feeding dietary sea tangle as an alternative mineral source results in an improvement in the physicochemical profiles of goat meat.