TRISCEND II: Novel Randomized Trial Design for Transcatheter Tricuspid Valve Replacement.

Severe tricuspid regurgitation remains largely undertreated given limited treatment options. Transcatheter tricuspid valve interventions have emerged as a promising therapy for these patients, and the TRISCEND II pivotal trial is the first randomized controlled trial to evaluate transcatheter tricuspid valve replacement (TTVR). The TRISCEND II pivotal trial studies the transcatheter EVOQUE (Edwards Lifesciences, Irvine, California) tricuspid valve replacement system using a United States Food and Drug Administration Breakthrough Device Designation-a program intended to provide timely access to medical devices by speeding up development, assessment, and review. The TRISCEND II trial is a prospective, multicenter trial that randomizes patients with symptomatic severe tricuspid regurgitation to treatment with either TTVR in conjunction with optimal medical therapy or optimal medical therapy alone. The trial's novel 2-phase design evaluates 30-day safety and 6-month effectiveness end points for the first 150 patients in the initial phase and a 1-year safety and effectiveness end point for the full cohort of 400 patients in the second phase. The TRISCEND II trial's 2-phase trial design provided an opportunity for early review and led to the first commercial approval of a TTVR system. In conclusion, the design of the TRISCEND II trial will likely inform future transcatheter tricuspid device trials.

Transgenerational exposure to marine heatwaves ameliorates the lethal effect on tropical copepods regardless of predation stress.

Marine heatwaves (MHWs) are emerging as a severe stressor in marine ecosystems. Extreme warm sea surface temperatures during MHWs often exceed the optimal thermal range for more than one generation of tropical coastal zooplankton. However, it is relatively unknown whether transgenerational plasticity (TGP) to MHWs may shape the offspring's fitness, particularly in an ecologically relevant context with biotic interactions such as predation stress. We addressed these novel research questions by determining the survival, reproductive success, and grazing rate of the copepod Pseudodiaptomus incisus exposed to MHW and fish predator cues (FPC) for two generations (F1 and F2). The experiment was designed in a full orthogonal manner with 4 treatments in F1 and 16 treatments in F2 generation. In both generations, MHW reduced P. incisus survival, reproductive parameters, and grazing by 10%-62% in MHW, but these parameters increased by 2%-15% with exposure to FPC, particularly at control temperature. F2 reproductive success and grazing rate as indicated by cumulative fecal pellets were reduced by 20%-30% in F1-MHW, but increased by ~2% in F1-FPC. Strikingly, MHW exposure reduced 17%-18% survival, but transgenerational exposure to MHWs fully ameliorated its lethal effect and this transgenerational effect was independent of FPC. Increased survival came with a cost of reduced reproductive success, constrained by reduced grazing. The rapid transgenerational MHW acclimation and its associated costs are likely widespread and crucial mechanisms underlying the resilience of coastal tropical zooplankton to MHWs in tropical coastal marine ecosystems.

Simultaneous nutrient recovery and algal biomass production from anaerobically digested sludge centrate using a membrane photobioreactor.

This study aims to evaluate the performance of C. vulgaris microalgae to simultaneously recover nutrients from sludge centrate and produce biomass in a membrane photobioreactor (MPR). Microalgae growth and nutrient removal were evaluated at two different nutrient loading rates (sludge centrate). The results show that C. vulgaris microalgae could thrive in sludge centrate. Nutrient loading has an indiscernible impact on biomass growth and a notable impact on nutrient removal efficiency. Nutrient removal increased as the nutrient loading rate decreased and hydraulic retention time increased. There was no membrane fouling observed in the MPR and the membrane water flux was fully restored by backwashing using only water. However, the membrane permeability varies with the hydraulic retention time (HRT) and biomass concentration in the reactor. Longer HRT offers higher permeability. Therefore, it is recommended to operate the MPR system in lower HRT to improve the membrane resistance and energy consumption.

Promotion of direct interspecies electron transfer and potential impact of conductive materials in anaerobic digestion and its downstream processing - a critical review.

Addition of conductive materials (CMs) has been reported to facilitate direct interspecies electron transfer (DIET) and improved anaerobic digestion (AD) performance. This review summarises the benefits and outlines remaining research challenges of the addition of CMs with a focus on the downstream processing of AD. CM addition may alter biogas quality, digestate dewaterability, biosolids volume, and centrate quality. Better biogas quality has been observed due to the adsorption of H2S to metallic CMs. The addition of CMs results in an increase in solid content of the digestate and thus an additional requirement for sludge dewatering and handling and the final biosolids volume for disposal. This review highlights the need for more research at pilot scale to validate the benefits of CM addition and to evaluate CM selection, doses, material costs, and the impact on downstream processes. The lack of research on the impact of CMs on the downstream process of AD is highlighted.

Parental exposures increase the vulnerability of copepod offspring to copper and a simulated marine heatwave.

Extreme temperatures from marine heatwaves (MHWs) and pollution are dominant stressors in tropical marine ecosystems. However, we know little about the role of transgenerational effects of metals and MHWs in shaping the offspring's vulnerability to these stressors. We addressed this fundamental knowledge gap by exposing the planktonic copepod Pseudodiaptomus incisus to copper (Cu: control, 15 and 60 µg L-1) under 2 temperatures (30 and a simulated marine heatwave at 34 °C) in the first generation (F1) and 16 treatments in F2: offspring from each of 4 F1 conditions (control or 15 µg Cu L-1 × 30 or 34 °C) was reared in 4 F2 conditions (control or 15 µg Cu L-1 × 30 or 34 °C). We assessed changes in copepod performance, particularly survival, adult size, grazing, and reproduction. In F1, Cu or marine heatwave (MHW) exposures reduced all fitness traits of F1; the effects were particularly strong when both stressors were present. Transgenerational effects of Cu or MHW also strongly reduced F2 performance. Direct Cu and MHW effects on the offspring were further strengthened by transgenerational effects, resulting in more substantial reductions in F2 performance when both generations were exposed to these stressors. As copepods are major food resources for corals, shrimps, or fish larvae and juveniles, strong transgenerational and direct effects of Cu and MHW can have a cascading effect on entire coastal food webs. These results highlight the importance of considering the interaction of transgenerational and direct effects of multiple stressors, particularly relevant for short-lived organisms in tropical marine ecosystems.

Harvesting Porphyridium purpureum using polyacrylamide polymers and alkaline bases and their impact on biomass quality.

This study aims to examine the flocculation efficiency of Porphyridium purpureum (i.e. a red marine microalga with high content of pigments and fatty acids) grown in seawater medium using polyacrylamide polymers and alkaline flocculation. Polymers Flopam™ and FO3801 achieved the highest flocculation efficiency of over 99% at the optimal dose of 21 mg per g of dry biomass through charge neutralisation and bridging mechanism. The addition of sodium hydroxide, potassium hydroxide, and sodium carbonate also achieved flocculation efficiency of 98 and 91%, respectively, but high doses were required (i.e. > 500 mg per g of dry biomass). Calcium hydroxide was not as effective and could only achieve 75% flocculation efficiency. Precipitation of magnesium hydroxide was identified as the major cause of hydroxide-induced flocculation. On the other hand, sodium carbonate addition induced flocculation via both magnesium and calcium carbonate co-precipitation. The large mass of precipitates caused a sweeping effect and enmeshed the microalgal cells to trigger sedimentation. Cell membrane integrity analysis of flocculated P. purpureum indicated that polyacrylamide polymers led to significant compromised cells (i.e. 96%), compared to the alkaline bases (70-96% compromised cells). These results appear to be the first to demonstrate the high efficiency of polyacrylamide polymer and alkaline flocculation of P. purpureum but at the expense of the biomass quality.

Biomethane production from anaerobic co-digestion at wastewater treatment plants: A critical review on development and innovations in biogas upgrading techniques.

Anaerobic co-digestion (AcoD) can utilise spare digestion capacity at existing wastewater treatment plants (WWTP) to generate surplus biogas beyond the plant's internal energy requirement. Data from industry reports and the peer-reviewed literature show that through AcoD, numerous examples of WWTPs have become net energy producers, necessitating other high-value applications for surplus biogas. A globally emerging trend is to upgrade biogas to biomethane, which can then be used as town gas or transport fuel. Water, organic solvent and chemical scrubbing, pressure swing adsorption, membrane separation, and cryogenic technology are commercially available CO2 removal technologies for biogas upgrade. Although water scrubbing is currently the most widely applied technology due to low capital and operation cost, significant market growth in membrane separation has been seen over the 2015-2019 period. Further progress in materials engineering and sciences is expected and will further enhance the membrane separation competitiveness for biogas upgrading. Several emerging biotechnologies to i) improve biogas quality from AcoD; ii) accelerate the absorption rate, and iii) captures CO2 in microalgal culture have also been examined and discussed in this review. Through a combination of AcoD and biogas upgrade, more WWTPs are expected to become net energy producers.

Interactive effects of extreme temperature and a widespread coastal metal contaminant reduce the fitness of a common tropical copepod across generations.

Tropical coastal areas are increasingly exposed to temperature extremes from marine heatwaves and contaminants from anthropogenic activities. The interactive effects of these environmental changes on marine life are understudied. We investigated the direct and cross-generational effects of copper (Cu) on F0 and F1 generations of the common tropical copepod Pseudodiaptomus annandalei under extreme temperatures (30 and 34 °C). In F0, Cu exposure reduced survival and nauplii production; these patterns were more pronounced at 34 °C and in females. F0 Copepods produced more faecal pellets at 34 °C than 30 °C, indicating a higher energetic demand. In F1, the number of F1 adults was lower in CuF0 and at 34 °C. Cu-exposed F0 produced larger adult F1, while exposure to 34 °C resulted in smaller adult F1. Our results show that tropical copepods are highly vulnerable to the interactive effects of contaminants and extreme temperatures.

A comprehensive review on the framework to valorise lignocellulosic biomass as biorefinery feedstocks.

An effective pretreatment is the first step to enhance the digestibility of lignocellulosic biomass - a source of renewable, eco-friendly and energy-dense materials - for biofuel and biochemical productions. This review aims to provide a comprehensive assessment on the advantages and disadvantages of lignocellulosic pretreatment techniques, which have been studied at the lab-, pilot- and full-scale levels. Biological pretreatment is environmentally friendly but time consuming (i.e. 15-40 days). Chemical pretreatment is effective in breaking down lignocellulose and increasing sugar yield (e.g. 4 to 10-fold improvement) but entails chemical cost and expensive reactors. Whereas the combination of physical and chemical (i.e. physicochemical) pretreatment is energy intensive (e.g. energy production can only compensate 80% of the input energy) despite offering good process efficiency (i.e. > 100% increase in product yield). Demonstrations of pretreatment techniques (e.g. acid, alkaline, and hydrothermal) in pilot-scale have reported 50-80% hemicellulose solubilisation and enhanced sugar yields. The feasibility of these pilot and full-scale plants has been supported by government subsidies to encourage biofuel consumption (e.g. tax credits and mandates). Due to the variability in their mechanisms and characteristics, no superior pretreatment has been identified. The main challenge lies in the capability to achieve a positive energy balance and great economic viability with minimal environmental impacts i.e. the energy or product output significantly surpasses the energy and monetary input. Enhancement of the current pretreatment techno-economic efficiency (e.g. higher product yield, chemical recycling, and by-products conversion to increase environmental sustainability) and the integration of pretreatment methods to effectively treat a range of biomass will be the steppingstone for commercial lignocellulosic biorefineries.

Author Correction: Extreme temperature impairs growth and productivity in a common tropical marine copepod.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Seawater-driven forward osmosis for pre-concentrating nutrients in digested sludge centrate.

Seawater-driven forward osmosis to enrich nutrients from sludge centrate and reduce membrane fouling is demonstrated. Due to enrichment and pH increase in the feed solution, without appropriate control measure, nutrient precipitation can occur directly on the membrane surface causing severe membrane fouling and reducing nutrient enrichment efficiency. Indeed without agitating the feed, there was less precipitation on the membrane surface, compared to with agitation. In addition, increase in the membrane area over permeate volume ratio significantly reduced the filtration time and nutrient precipitation. A novel technique to maintain the draw solution (DS) at an acidic condition was developed to improve nutrient enrichment and reduce membrane fouling. By using this technique and a high membrane surface to permeate volume ratio, nutrient enrichment similar to the theoretical efficiency was successfully demonstrated. Our technique reduced the filtration time to achieve 70% water recovery by over 90% (compared to unbuffered seawater as the DS, small membrane area, and feed agitation), as a result of significantly less membrane fouling. The amount of phosphorus precipitate on the membrane surface decreased by more than 10 times. The enrichment of ammonia and phosphorus as a function of water recovery was similar to the theoretical calculation, indicating negligible nutrient loss due to precipitation.

Extreme temperature impairs growth and productivity in a common tropical marine copepod.

Shallow, tropical marine ecosystems provide essential ecosystem goods and services, but it is unknown how these ecosystems will respond to the increased exposure to the temperature extremes that are likely to become more common as climate change progresses. To address this issue, we tracked the fitness and productivity of a key zooplankton species, the copepod Pseudodiaptomus annandalei, acclimated at two temperatures (30 and 34 °C) over three generations. 30 °C is the mean temperature in the shallow water of the coastal regions in Southeast Asia, while 34 °C simulated a temperature extreme that occurs frequently during the summer period. For each generation, we measured the size at maturity and reproductive success of individuals. In all three generations, we found strong negative effects of warming on all measured fitness-related parameters, including prolonged development time, reduced size at maturity, smaller clutch sizes, lower hatching success, and reduced naupliar production. Our results suggest that P. annandalei are already exposed to temperatures that exceed their upper thermal optimum. Increased exposure to extreme temperatures may reduce the abundance of these tropical marine copepods, and thus reduce the availability of resources to higher trophic levels.