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Enriched Rotifers (
No full textThe availability of high-quality natural feed is one of the key factors in the successful cultivation of barramundi (Lates calcarifer) larvae. Rotifers (Brachionus plicatilis) are the main feed during the early larval stage; however, their nutritional content needs to be improved through an enrichment process. Rotifers, as natural feed for fish larvae, not only provide protein and other nutrients, but are also considered living capsules capable of transferring micromolecules. Another advantage of rotifers is their very slow movement, making them easy for fish larvae to catch. Several studies on the enrichment of rotifers using specific types of vitamins have been conducted, but they have not yet been applied to specific fish species. This study aimed to analyze the effect of enriched rotifers on the growth and survival of barramundi larvae. The study was conducted from day 2 to day 17. The treatments tested were: A (Chlorella sp.+ yeast), B (Chlorella sp. + yeast + Ascorbic acid), C (Chlorella sp. + yeast + Cobalamin), and D (Chlorella sp. + yeast + Ascorbic acid + Cobalamin). The results showed that treatment D produced the highest absolute length growth of 0.95 cm, while treatment B resulted in the highest survival rate of 41.7%
Effect of ultrafiltration on the antioxidant activity of alcalase-hydrolyzed catfish (
No full textCatfish (Clarias sp.) is one of Indonesia's leading aquaculture commodities with potential utilization as a source of functional protein. Protein hydrolysis using alcalase enzyme can generate bioactive peptides with antioxidant activity. These antioxidant properties are typically more prominent in low-molecular-weight peptides, thus requiring separation via ultrafiltration. This study aimed to evaluate the effect of ultrafiltration on the antioxidant activity of catfish protein hydrolysate. Hydrolysis was carried out using alcalase at concentrations of 1%, 2%, and 3%, followed by fractionation using a 3 kDa molecular weight cut-off (MWCO) ultrafiltration membrane. Antioxidant activity was assessed using the DPPH and ABTS assays. The highest degree of hydrolysis (62,42%) was obtained at 3% enzyme concentration. The <3 kDa fraction exhibited the highest antioxidant activity, with IC50 values of 41,20 ppm (DPPH) and 2,80 (ABTS), both categorized as very strong antioxidants. These findings indicate that ultrafiltration is an effective method for enriching short peptides with high antioxidant potential
Décoder les données qualitatives : aux sources de la question interprétative
No full textContexte et problématique : De nombreux groupes de recherche en Europe et en Amérique du Sud et du Nord se heurtent à la question de la gestion de l’ambiguïté des données qualitatives comparativement aux données numériques du quantitatif. Un mot est plus difficile à interpréter qu’un écart entre deux valeurs numériques. Ceci décourage les chercheurs en santé à se tourner vers la recherche qualitative, malgré ses avantages amplement démontrés. Exégèse : Ce texte débute par un regard critique sur la nature de la connaissance, pour y exposer deux paradigmes complémentaires. Le paradigme pragmatique se démarque du paradigme positiviste notamment en raison des multiples réponses possibles à une seule question. Le texte conclut par une présentation des dispositifs soutenant la rigueur de l’interprétation des données qualitatives, notamment l’importance d’un cadre conceptuel et des critères de scientificité. Conclusion : La science ne peut échapper entièrement à l’interprétation. Loin de vouloir approfondir la polarisation entre postures positivistes et pragmatiques, ce texte se veut un argument pour la complémentarité entre les deux
Dielectric spectroscopy of emulsified high-density amorphous ice: the emulsion effect on the dielectric spectrum
No full textDielectric spectroscopy measurements of bulk and emulsified high-density amorphous ices (HDA) at 1.0 GPa were carried out to examine the effect of emulsion matrix on the dielectric spectra. The presence of emulsion matrix induces the shifts of the loss peak to higher frequency side. The degree of shift depends on the volume fraction of the emulsion matrix to HDA. This indicates that the relaxation time obtained from the dielectric spectra of emulsified HDA is underestimated than the true relaxation time of HDA. The results suggest that the emulsified sample is not appropriate for dielectric spectroscopy measurement in water polyamorphism study, although the emulsification is effective, for example, in avoiding water crystallization
Identification potential sources of marine debris based on backward trajectory modelling in Tidung Island
No full textMarine debris poses an increasing threat to the coastal ecosystems of the Seribu Islands, particularly Tidung Island, where hydrodynamic influences on debris transport remain poorly understood. This study simulated the movement and seasonal origin of floating debris using backward modeling integrated with validated hydrodynamic and Lagrangian modules in OpenFlows FLOOD. The model, forced by tidal, wind, and bathymetric data, showed strong agreement with the field observations, with correlation coefficients of 0.84–0.94, and RMSE values of 0.069–0.097 across tidal elevation and currents. Simulations under contrasting monsoon conditions revealed current velocities of 0.10–0.28 m/s during the west monsoon and 0.03–0.24 m/s during the east monsoon, producing southwestward flow in the west season and weaker northwestward circulation in the east. Backward analysis showed that during the western monsoon, offshore debris from the northern Java Sea was advected southward and accumulated near Tidung Island, whereas during the east monsoon, debris mainly originated from local activities and remained confined due to weak circulation. These findings highlight the dual role of Tidung Island as both a receiver of offshore debris and a trap for local waste, underscoring the need for stronger community management and integrated policy actions to reduce marine debris
Effectivenes of
No full textIndustrial development poses a serious threat to marine ecosystems and biota in Indonesia. Waste released into the environment includes inorganic substances such as heavy metals Lead (Pb) and Cobalt (Co). An effort to restore contaminated environments is bioremediation using Halimeda sp. It is an alga capable of acting as a bioremediation agent through phytoremediation. This study aimed to determine the effectiveness of Halimeda sp. as a bioremediation agent for seawater contaminated with the heavy metals Lead (Pb) and Cobalt (Co). The study was conducted at a laboratory scale by culturing Halimeda sp. algae in 500 ml glass jars with heavy metal concentrations of 1.5, 3, and 6 ppm. The results of heavy metal content testing showed that Halimeda sp. are capable of absorbing heavy metals. Lead (Pb) absorption at concentrations of 1.5, 3, and 6 ppm was 87.83%, 90.17%, and 98.50%, respectively, and Cobalt (Co) absorption at the same concentrations was 99.17%, 98.40%, and 98.01%, respectively. These test results indicate that Halimeda sp. has a high potential for remediating heavy metal Lead (Pb) by bioaccumulation via absorption
Mirror-stacked tetra-missing rib honeycomb with persistent zero Poisson's ratio
No full textZero Poisson's ratio (ZPR) structures have attracted significant attention due to their remarkable dimensional stability, mechanical decoupling capability, and reduction of contact-induced effects, making them desirable in various engineering applications. However, most existing ZPR structures suffer from limited adaptability under large strains, which restricts their practical implementation. To address this challenge, this study proposes a novel ZPR design based on a mirror-stacked tetra-missing rib honeycomb (MSTMH) with monoclinic chirality. The mirror-stacked configuration effectively suppresses the Poisson's effect in the transverse direction, enabling a stable zero Poisson's ratio behavior over a wide strain range. To evaluate its performance, four MSTMH samples were fabricated using 3D printing, and uniaxial tensile tests were conducted. Finite element (FE) simulations and theoretical derivations were further employed to analyze key structural parameters, including the effective elastic modulus and ZPR strain range. The theoretical predictions show good agreement with both the experimental and numerical results. This work provides new insights and design strategies for achieving highly stable and large-deformation-tolerant ZPR metamaterials
Experimental confirmation of hyperuniformity of torque fluctuations in frictional matter
No full textA recent purely theoretical prediction stated that in frictional granular packings, mechanical balance and material isotropy constrain the stress auto-correlation matrix to be fully determined by two spatially isotropic functions: the pressure and torque auto-correlations. Moreover, and unexpectedly, the torque fluctuations were predicted to be hyperuniform, a condition for the stress auto-correlation to decay as the elastic Green's function. In this letter we present first experimental evidence for the hyperuniformity of the stress fluctuations. We propose that quite generally the variance of torque fluctuations in a d-dimensional ball of radius R will increase exactly like , satisfying the definition of hyperuniformity
Discovery of linear propadienone
No full textWe report the first detection in space of propadienone, the linear isomer (l-H2C3O) of cyclopropenone (c-H2C3O). We also report the first detection of the isotopologues c-H213 CCCO and c-HDCCCO of c-H2C3O. The astronomical observations are part of QUIJOTE, a line survey of TMC-1 in the frequency range 31.0–50.3 GHz, complemented with data between 71.6–116.0 GHz, and carried out with Yebes-40 m and IRAM-30 m telescopes, respectively. We obtain a total column density of 3.7 × 1010 cm−2 for l-H2C3O at an excitation temperature of 4.8 K. We find that the isomer is about eight times less abundant than the cyclic one. We also report a detailed line-byline study of cyclopropenethione (c-H2C3S) to compare the abundance of the O and S isomers. We find that cyclic O-isomers are more abundant than cyclic S-isomers; however, the opposite trend is found for the most stable linear isomers, with l-H2C3S being more than one order of magnitude more abundant than l-H2C3O. A comprehensive theoretical chemical analysis shows that the abundances of the H2C3O and H2C3S isomers are controlled by different formation pathways. In particular, while l-H2C3O is potentially produced by dissociative electron recombination reactions, ion-neutral chemistry is more effective at producing l-H2C3S and c-H2C3S
Development of monitoring and early warning model for harmful trace elements in the environment of grain crop planting in Jilin Province
No full textAccompanied by urbanization and industrial development, the introduction of fertilizers, pesticides, and waste materials into the soil and water has resulted in heavy metal pollution of arable land and water sources, posing a serious threat to food and agricultural product safety, and bringing significant potential harm to human health. This paper focuses on central Jilin (Changchun, Siping, and Songyuan) as the study area, with primary research on the total-effective-plant seed content of heavy metals and their transformation and accumulation, in conjunction with land use data. It explores the constraints of heavy metal pollution in arable soil and the efficiency of its transformation and accumulation in relation to arable land use in the black soil region, aiming to provide a theoretical basis for the sustainable use of arable resources in the context of rapid urbanization in black soil areas