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Epiphytism commonly occurs in marine benthic macroalgae and seagrass communities under natural conditions and those of mariculture. This can greatly obstruct the cultivation of commercial seaweeds and ultimately impacts the seaweed aquaculture industry negatively. Against a background of climate change and a rapidly increasing market demand, the commercial Sargassum species is experiencing increasing challenges posed by epiphytic macroalgae. Severely reduced growth, lower quality, the emergence of diseases, and the ultimate death of the algae can lead to a commercial loss. Attempts to limit epiphytic macroalgae in aquaculture have so far been inefficient. However, epiphytic macroalgae are also rich in nutritional compounds and their relative biomass could be used as efficiently as the cultivated seaweed. As epiphytes cannot effectively be controlled by the current physical, chemical, and other methods in most cases, the perspective of comprehensive utilization could be an alternative over complete prevention and control by traditional methods. Compared to the existing strategies for controlling the growth and spread of epiphytes in seaweed aquaculture, the integrated and indiscriminate harvest and utilization of epiphytic macroalgae as fertilizer, animal food additive agents, as well as the development of biodegradable materials, might prove to be alternative valorization. However, the implementation of epiphytic macroalgae utilizations still needs to overcome the technical obstacles.

In this study, five drying methods (hot air drying [HD], light wave drying [LD], far infrared drying [FID], freeze drying [FD], and heat pump drying [HPD]) were applied to dry Sargassum fusiforme. The color, rehydration rate (RR), and volatile flavor substances of dried S. fusiforme were compared and analyzed, and the content, molecular weight (Mw), monosaccharide composition, and antioxidant activity of dried S. fusiforme crude polysaccharides (SFCPs) were analyzed. The results showed that S. fusiforme dried by different drying methods showed different colors. FD produced S. fusiforme with better RR (p < 0.05). The Mw of the SFCPs were 624.06, 534.86, 683.00, 1077.13, and 981.91 kDa, respectively, for HD, LD, FID, FD, and HPD. The Mw and DPPH (1,1‐diphenyl‐2‐picrylhydrazyl) radical scavenging rates of SFCP‐FD were greater than those of the remaining four drying methods; however, the ABTS (2,2 ′‐azobis‐3‐ethylbenzothiazoline‐6‐sulfonic acid) and OH (hydroxyl) radical scavenging rates were highest in the SFCP‐HPD. GC‐IMS analysis showed that the drying method affected the content and composition of volatile flavor compounds. Principal component analysis (PCA) analysis indicated that the flavors of dried S. fusiforme were quite different from that of fresh S. fusiforme, and the flavors of HD, LD, and FID were similar, while the flavors of FD and HPD were similar. [ABSTRACT FROM AUTHOR]

The physical properties of shale reservoirs are typically poor, necessitating the use of fracturing technology for effective development. However, the high clay content prevalent in shale formations poses significant challenges for conventional hydraulic fracturing methods. To address this issue, CO2-based fracturing fluid has been proposed as an alternative to mitigate the damage caused by water-based fracturing fluids. In this paper, the applicability of quasi-dry CO2 fracturing in shale reservoirs is examined from three key perspectives: the viscosity of CO2 fracturing fluid, the fracture characteristics induced by the CO2 fracture fluid, and the potential reservoir damage caused by the fracturing fluid. Firstly, the viscosity of CO2 fracturing fluid was determined by a rheological experiment. Rheological tests revealed that the viscosity of CO2 fracturing fluid was significantly influenced by the water–carbon ratio. Specifically, when the water–carbon ratio was 30:70, the maximum viscosity observed could reach 104 mPa·s. Moreover, increasing reservoir temperature resulted in decreased fracturing fluid viscosity, with a 40 °C temperature rise causing a 20% viscosity reduction. Secondly, matrix permeability tests were conducted to investigate permeability alteration during CO2 fracturing fluid invasion. Due to the weak acidity of CO2-based fracturing fluid, the permeability reduction induced by clay hydration was inhibited, and an increase in permeability was observed after a 3-day duration. However, the matrix permeability tends to decrease as the interaction time is prolonged, which means prolonged soaking time can still cause formation damage. Finally, triaxial fracturing experiments facilitated by a three-axis servo pressure device were conducted. The fracture properties were characterized using computed tomography (CT), and 3D reconstruction of fractured samples was conducted based on the CT data. The results demonstrate that CO2 fracturing fluid effectively activates weak cementation surfaces in the rock, promoting the formation of larger and more complex fractures. Hence, CO2 quasi-dry fracturing technology emerges as a method with significant potential, capable of efficiently stimulating shale reservoirs, although a reasonable soaking time is necessary to maximize hydrocarbon production. [ABSTRACT FROM AUTHOR]

To improve the quality of Sargassum fusiforme seedlings, suitable strains of juveniles regenerated from holdfasts need to be bred. In this study, effects of different temperatures (16, 20, and 24 °C) and irradiances (100, 120, and 160 µmol photons·m−2·s−1) on the growth of juveniles (new individuals) from the holdfasts of S. fusiforme were investigated to provide strategies for the cultivation of vegetative propagation seedlings of S. fusiforme. The results demonstrated that during cultivation at 24 °C, the regenerated juveniles rotted after twenty-one days, and their relative growth rate, photosynthetic activity and pigment content decreased substantially. The low temperature of 16 °C also decreased their photosynthetic activity and growth considerably. At a high irradiance of 160 µmol photons·m−2·s−1, the growth rate and photosynthetic activity decreased. Under conditions of 20 °C and 120 µmol photons·m−2·s−1, juveniles showed higher photosynthetic activity and nitrate uptake rates, which increased the growth of the juveniles and lateral branches and promoted the accumulation of photosynthetic pigment. Therefore, culture conditions of 20 °C and 120 µmol photons·m−2·s−1 can be applied for early indoor cultivation of regenerated juveniles of S. fusiforme. This study provided technical support for solving the problem of single provenance of S. fusiforme seedlings. [ABSTRACT FROM AUTHOR]