Search Results (257)

Though the pursuit of sustainable desalination processes with high water recovery has intensified the research interest in membrane distillation (MD), the influence of module connection configuration on performance stability remains poorly explored. The current study provided a comprehensive multiparameter assessment of hollow fibre membrane modules connected in parallel and series in direct contact membrane distillation (DCMD) for the first time. The configurations were evaluated under varying process parameters such as temperature (50–70 °C), flow rates (22.1–32.3 mL·s⁻¹), magnesium concentration as scalant (1.0–4.0 g·L⁻¹), and flow direction (co-current and counter-current), assessing their influence on temperature gradients (∆T), flux and pH stability, salt rejection, and crystallisation. Interestingly, the parallel module configuration maintained high operational stability with uniform flux and temperature differences (∆T) even at high recovery factors (>75%). On one hand, the serial configuration experienced fluctuating ∆T caused by thermal and concentration polarisation, causing an early crystallisation (abrupt drop in feed conductivity). Intensified polarisation effects with accelerated crystallisation increased the membrane risk of wetting, particularly at high recovery factors. Despite these changes, the salt rejection remained relatively high (99.9%) for both configurations across all tested conditions. The findings revealed that acidification trends caused by MgSO₄ were configuration-dependent, where the parallel setup-controlled rate of pH collapse. This study presented a novel framework connecting membrane module architecture to mass and heat transfer phenomena, providing a transformative DCMD module configuration design in water desalination. These findings not only provide the critical knowledge gaps in DCMD module configurations but also inform optimisation of MD water desalination to achieve high recovery and stable operation conditions under realistic brine composition. Full article

Heuristic optimization is used to find sustainable cogeneration steam power plants with steam reheat and supercritical main steam parameters. Design solutions are analyzed for steam consumer (SC) pressures of 3.6 and 40 bar and a heat flow rate of 40% of the fuel heat flow rate. The objective functions consisted in simultaneous maximization of global and exergetic efficiencies, power-to-heat ratio in full cogeneration mode, and specific investment minimization. For 3.6 bar, the indicators improve with the increase in the ratio between reheating and main steam pressure. The increase in SC pressure worsens the performance indicators. For an SC steam pressure of 40 bar and 9 feed water preheaters, the ratio between reheating and main steam pressure should be over 0.186 for maximum exergetic efficiency and between 0.10 and 0.16 for maximizing both global efficiency and power-to-heat ratio in full cogeneration mode. The average global efficiency for an SC requiring steam at 3.6 bar is 4.4 percentage points higher than in the case with 40 bar, the average specific investment being 10% lower. The Pareto solutions found in this study are useful in the design of sustainable cogeneration supercritical power plants. Full article

Permeate Gap Membrane Distillation (PGMD) is an emerging desalination technology that offers a promising alternative for freshwater production, particularly in energy-efficient and sustainable applications. This review provides a comprehensive analysis of PGMD, covering its fundamental principles, heat and mass transfer mechanisms, and key challenges such as temperature and concentration polarization. Various optimisation strategies, including Response Surface Morphology (RSM), Differential Evolution techniques, and Computational Fluid Dynamics (CFD) modelling, are explored to enhance PGMD performance. The study further discusses the latest advancements in system design, highlighting optimal configurations and the integration of PGMD with renewable energy sources. Factors influencing PGMD performance, such as operational parameters (flow rates, temperature, and feed concentration) and physical parameters (gap width, membrane properties, and cooling plate conductivity), are systematically analysed. Additionally, the techno-economic feasibility of PGMD for large-scale freshwater production is evaluated, with a focus on cost reduction strategies, energy efficiency, and hybrid system innovations. Finally, this review outlines the current limitations and future research directions for PGMD, emphasising novel system modifications, improved heat recovery techniques, and potential industrial applications. By consolidating recent advancements and identifying key challenges, this paper aims to guide future research and facilitate the broader adoption of PGMD in sustainable desalination and water purification processes. Full article

This study investigates the effects of heat stress in a climate chamber from day 0 to 28 days of life on physiological responses, intake, nutrient digestibility, immunity, and performance in neonatal Holstein calves. Thirty-four calves (nineteen females, fifteen males) were randomly assigned to a control group (CON, temperature–humidity index [THI] 66, with 22 °C and 65% humidity for 24 h, n = 17) or a heat-stressed (HS) group, which was exposed to a THI of 82, 32 °C, and 65% humidity for 9 h, followed by a THI of 66, 22 °C, and 65% humidity for 15 h. The HS calves exhibited increased respiratory rates and rectal temperatures (p < 0.001), particularly during heat exposure periods, as well as a 59.5% increase in water intake compared to CON. While milk and solid feed intake, average daily gain, and feed efficiency were similar between groups, HS calves had reduced ether extract digestibility and altered ruminal fermentation, including lower acetate and lower propionate concentrations. The blood cytokine analysis showed elevated interleukin-4 and reduced interleukin-8 and IP-10 levels in heat-stressed calves, indicating a shift toward an anti-inflammatory immune profile. Despite no major performance impairments, heat stress has induced clear physiological, digestive, and immunological changes. These results underscore the importance of implementing thermal mitigation strategies during early life to safeguard calf health and development in increasingly warmer climates. Full article

This study aimed to evaluate the microbiological quality of colostrum on three dairy farms with different colostrum management hygiene practices and to compare it with the current colostrum quality guidelines. On farm A, colostrum was fed raw, while on farms B and C it was heat treated. On farms A and B, the feeding equipment was cleaned manually, while on farm C, an automated cleaning system was used. Samples were collected from the calf-feeding equipment and submitted for microbial culture: total plate count (TPC); total coliform count (TCC); and E. coli, enterobacteria (ENTB), staphylococci (STAP), and lactic acid bacteria counts. In addition, pH, water activity (a_W), and Brix were analyzed. Colostrum quality was defined as follows: good quality (GQ)—TPC < 100,000, TCC < 10,000, STAP < 50,000 cfu/mL, and Brix ≥ 22%; excellent quality (EQ)—TPC < 20,000, TCC < 100, STAP < 5000 cfu/mL, and Brix ≥ 25%. Mean concentrations were as follows: TPC was 3.99 × 10⁵ cfu/mL (min: 40.00, max: 1.32 × 10⁷ cfu/mL); TCC was 1.17 × 10⁴ cfu/mL (min: <detection limit, max: 6.37 × 10⁵ cfu/mL); and STAP was 1.77 × 10⁴ cfu/mL (min: <detection limit, max: 3.50 × 10⁵ cfu/mL). Approximately 54% (GQ) and 32% (EQ) of samples met the defined criteria. Farm C consistently showed lower microbial counts across all culture types. Colostrum from farm B had lower TCC, LAB, and E. coli counts than farm A but not TPC, STAP, and ENTB. These results showed that a considerable proportion of calves were fed colostrum with suboptimal quality, especially when less rigorous hygiene practices were implemented. Full article

Tetrodotoxin (TTX), earlier known as a tropical paralytic neurotoxin from pufferfish poisoning, has increasingly been occurring in edible marine species, including filter-feeding bivalves, from relatively cold marine waters of some European countries. The defined conditions that promote the production of TTX, its origin or the processes of its accumulation in seafood are still not clarified. Recent studies in temperate waters show, however, that the accumulation of quantifiable levels of TTX in bivalves appears to be influenced by seawater temperature (>15 °C), which indicates a seasonal occurrence at these latitudes. Uncertainties still remain regarding how seawater temperature interacts with other climate and environmental factors or organisms in the marine ecosystem to result in detectable levels of TTX in shellfish. Knowledge of the occurrence and distribution of TTX in the marine environment where the edible bivalves grow is important for maintaining seafood safety, as the toxin is heat-stable and remains potent even after cooking. Therefore, in this study, 264 bivalve samples collected in 2019 and 2021 from 17 sites along the Swedish west coast were analyzed with LC-MS/MS to search for TTX. The study explores the hypothesis of TTX presence in Swedish marine waters, outlines the sample screening strategy and objectives, and reports no evidence of TTX presence in Swedish bivalve shellfish (≥7.8 µg/kg) based on the analyzed samples and the time periods in which the studied samples were collected. Full article

Yellow perch (Perca flavescens), a native species of the Great Lakes, has experienced a significant decline in wild harvest since the 1990s, leading to an increased reliance on aquaculture. This study aimed to optimize feeding rate for yellow perch by evaluating the effects of various feeding rates (1.5%, 3.0%, 4.5%, 6.0%, and 7.5% body weight (BW)/day) on growth, nutrient retention, and heat shock protein 70 expression in perch fingerlings (initial BW: 1.73 ± 0.11 g) over a four-week period. Following the feeding trial, an acute heat shock was induced by raising the water temperature from 23 °C to 31 °C, followed by an 18 h recovery period. Results indicated that both growth rate and whole fish lipid content increased with higher feeding rates (p < 0.05), while nutrient retention decreased. Growth and energy retention did not significantly improve beyond 4.5%, with maximum energy retention observed at 3.9% BW/day. Heat shock protein 70 expression was highest in liver tissue at a feeding rate of 6.2% BW/day, indicating that higher feeding levels may enhance thermal stress response. These results indicate that a feeding rate of 4.5% BW/day supports optimal growth, while 6.2% BW/day may be necessary to improve heat shock tolerance. The study provides practical insights for refining feeding strategies in yellow perch aquaculture. Full article

A novel design of a proton exchange membrane electrolyzer is presented. In contrast to previous designs, the flow field plates are round and oriented horizontally with the feed water entering from a central hole and spreading evenly outward over the anode flow field in radial, interdigitated flow channels. The cathode flow field consists of a spiral channel with an outlet hole near the outside of the bipolar plate. This results in anode and cathode flow channels that run perpendicular to avoid shear stresses. The novel sealing concept requires only o-rings, which press against the electrolyte membrane and are countered by circular gaskets that are placed over the flow channels to prevent the membrane from penetrating the channels, which makes for a much more economical sealing concept compared to prior designs using custom-made gaskets. Hydrogen leaves the electrolyzer through a vertical outward pipe placed off-center on top of the electrolyzer. The electrolyzer stack is housed in a cylinder to capture the oxygen and water vapor, which is then guided into a heat exchanger section, located underneath the electrolyzer partition. The function of the heat exchanger is to preheat the incoming fresh water and condense the escape water, thus improving the efficiency. It also serves as internal phase separator in that a level sensor controls the water level and triggers a recirculation pump for the condensate, while the oxygen outlet is located above the water level and can be connected to a vacuum pump to allow for electrolyzer operation at sub-ambient pressure to further increase efficiency and/or reduce the iridium loading. Full article

This study explores the creation and characterization of a compostable biopolymer derived from banana peels, addressing the issue of organic waste. Rich in protein, fiber, water, and cellulose, banana peels can be transformed into biodegradable polymers through acid hydrolysis, which breaks down cellulose chains, making them suitable for use in aquiculture and agriculture. Methionine, an essential amino acid for aquiculture, was added to enhance the biopolymer’s value in fish feed. The biopolymer was synthesized by heating, crushing, and subjecting the peels to acid hydrolysis. The methionine was integrated by causing it to form ester bonds with the cellulose. The products were characterized using UV-VIS and IR spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). UV-VIS and IR spectra confirmed the incorporation of the methionine, while TGA showed reduced mass loss in the methionine-enriched biopolymer, likely due to the retention of water molecules. SEM images revealed roughness, indicating the crosslinking of the small cellulose chains. The incorporation of methionine led to a more uniform and compact structure. The obtained biopolymer has potential applications in agriculture, especially for potato cultivation, and shows promise for sustainable aquiculture, particularly in tilapia feed. This research contributes to both waste valorization and the development of eco-friendly materials. Full article

A study was designed to explore the possibility of using herbal supplementation to sustain growth performance during heat stress exposure in Kenguri sheep. This 60-day study was conducted on 24 Kenguri ewes (1–2 years old), randomly assigned to four treatment groups (n = 6 per group) as follows: KC (n = 6; Kenguri Control), KHS (n = 6; Kenguri Heat Stress), KCS (n = 6; Kenguri Control and herbal supplement), and KHSS (n = 6; Kenguri Heat Stress and herbal supplement). The herbal mixture of Ocimum sanctum (Tulsi), Emblica officinalis (Amla), Morinda citrifolia (Noni), Withania somnifera (Ashwagandha), and Phyllostachys edulis (Bamboo) was used in this study. The herbal supplement used in the present study was given to the KCS and KHSS groups’ animals in dry powder form at a dose of 0.8 g/Kg BW/Day. All variables were recorded fortnightly, and gene expression analysis was performed at the end of the experiment. The results indicated that the recorded temperature–humidity index (THI) provided thermal comfort for KC and KCS while inducing extremely severe heat stress to the KHS and KHSS groups. Heat stress did not alter the feed intake, while the herbal supplement during heat stress increased the feed intake from day 30 onwards. Furthermore, heat stress significantly (p < 0.001) increased the water intake, while the herbal supplement did not alter the heat stress-induced water intake. In addition, neither heat stress nor herbal supplements influenced the body weight and allometric measurements studied. Furthermore, heat stress significantly (p < 0.01) decreased the level of plasma tri-iodo-thyronine (T₃) and thyroxin (T₄) and had a non-significant effect on plasma growth hormone (GH), insulin-like growth factor-1 (IGF-1), while the herbal supplements significantly (p < 0.01) increased the levels of all these hormones studied. Likewise, in peripheral blood mononuclear cells (PBMCs) the expression patterns of growth hormone receptor (GHR), Insulin-like growth factor 1 (IGF1) and prolactin receptor (PRLR) were significantly (p < 0.001) downregulated during heat stress (0.25, 0.3, and 0.48-fold change, respectively). However, the herbal supplement significantly (p < 0.01) increased the heat stress-induced reduction in the expression pattern of these three genes (0.65, 0.61, and 0.61-fold change, respectively). Therefore, from this study, it could be concluded that although the herbal supplements did not bring positive changes in body weight and allometric measurements, it still had a beneficial impact on the endocrinology and genes governing growth performance in Kenguri ewes. Thus, the herbal feed additive used in the study shows promise for relieving heat stress in Kenguri ewes. Full article

Optimizing building equipment control is crucial for enhancing energy efficiency. This article presents a predictive control applied to a commercial building heated by a hydronic system, comparing its performance to a traditional heating curve-based strategy. The approach is developed and validated using TRNSYS18 modeling, which allows for comparison of the control methods under the same weather boundary conditions. The proposed strategy balances energy consumption and indoor thermal comfort. It aims to optimize the control of the secondary heating circuit’s water setpoint temperature, so it is not the boiler supply water temperature that is optimized, but rather the temperature of the water that feeds the radiators. Limited data poses challenges for capturing system dynamics, addressed through a black-box approach combining two machine learning models: an artificial neural network predicts indoor temperature, while a support vector machine estimates gas consumption. Incorporating weather forecasts, occupancy scenarios, and comfort requirements, a genetic algorithm identifies optimal hourly setpoints. This work demonstrates the possibility of creating sufficiently accurate models for this type of application using limited data. It offers a simplified and efficient optimization approach to heat control in such buildings. The case study results show energy savings up to 30% compared to a traditional control method. Full article

Background: Global warming poses significant challenges to aquaculture, as elevated water temperatures adversely affect fish health and survival. This study investigated the effects and potential mechanisms of dietary tea polyphenols (TPs) on acute heat stress and survival in hybrid crucian carp HCC2. Methods: The fish in the control (CON) group and heat stress group (HS group, three replicates, each containing 20 fish, n = 60 per group) were fed diets with 0 mg/kg TPs, and the three experimental groups (HSLTP, HSMTP, and HSHTP, n = 20 × 3 replicates) were fed the diets with 100, 200, or 400 mg/kg TPs for 60 days. Further, fish in the experimental groups (HS, HSLTP, HSMTP, and HSHTP) were exposed at 38 °C for 24 h to induce acute heat stress. Survival data and serum and tissue samples were collected for the analysis. Metabolomics using UPLC-Q-TOF/MS was employed to evaluate the metabolite changes in the fish livers. Results: Notably, dietary TPs significantly improved survival rates and antioxidant enzyme levels and reduced serum ALT, AST, cortisol, glucose, MDA, and liver HSP-70 levels in the heat-stressed fish. Metabolomic analysis revealed that TPs modulated lipid metabolism, particularly glycerophospholipid and arachidonic acid pathways, which may contribute to a higher tolerance to acute heat stress. Conclusions: These findings suggest that TPs are a promising, eco-friendly feed additive for protecting fish from heat stress and optimizing aquaculture practices. Full article

Membrane distillation (MD) is an evolving thermal separation technique most frequently aimed at water desalination, compatible with low-grade heat sources such as waste heat from thermal engines, solar collectors, and high-concentration photovoltaic panels. This study presents a comprehensive theoretical–experimental evaluation of three commercial membranes of different materials (PE, PVDF, and PTFE), tested for two distinct MD modules—a Direct Contact Membrane Distillation (DCMD) module and an Air Gap Membrane Distillation (AGMD) module—analyzing the impact of key operational parameters on the performance of the individual membranes in each configuration. The results showed that increasing the feed saline concentration from 7 g/L to 70 g/L led to distillate flux reductions of 12.2% in the DCMD module and 42.9% in the AGMD one, averaged over the whole set of experiments. The increase in feed temperature from 65 °C to 85 °C resulted in distillate fluxes up to 2.36 times higher in the DCMD module and 2.70 times higher in the AGMD one. The PE-made membrane demonstrated the highest distillate fluxes, while the PVDF and PTFE membranes exhibited superior performance under high-salinity conditions in the AGMD module. Membranes with high contact angles, such as PTFE with 143.4°, performed better under high salinity conditions. Variations in operational parameters, such as flow rate and temperature, markedly affect the temperature and concentration polarization effects. The analyses underscored the necessity of a careful selection of membrane type for each distillation configuration by the specific characteristics of the process and its operational conditions. In addition to experimental findings, the proposed heat and mass transfer-reduced model showed good agreement with experimental data, with deviations within ±15%, effectively capturing the influence of operational parameters. Theoretical predictions showed good agreement with experimental data, confirming the model’s validity, which can be applied to optimization methodologies to improve the membrane distillation process. Full article

This study investigated the potential of dietary gamma-aminobutyric acid (GABA) inclusion to mitigate acute temperature stress impacting the physiological resilience of juvenile olive flounder (Paralichthys olivaceus). A total of 360 juvenile fish, with an average initial weight of 12.97 ± 0.1 g (mean ± SEM), were randomly assigned in triplicate to 18 tanks (20 fish per tank) and reared at 19.5 °C for 8 weeks, with bi-monthly collection of growth performance data. The fish were fed one of six experimental diets: control (GABA74), 174 ppm of GABA (GABA174), 275 ppm of GABA (GABA275), 396 ppm of GABA (GABA396), 476 ppm of GABA (GABA476), and 516 ppm of GABA (GABA516). At the end of the trial, one group of fish was subjected to lethal temperature stress (31 °C) for 48 h, while another was exposed to acute temperature stress (29 °C) for 6 h. Growth performance remained relatively stable across all inclusion levels (p > 0.05), with the final body weight (FBW) ranging from 48.2 ± 0.3 g (GABA174) to 50.3 ± 0.6 g (GABA516) and the feed conversion ratio (FCR) varying between 2.06 ± 0.07 (GABA396) and 2.35 ± 0.07 (control). There were no significant differences in average whole-body composition across all dietary treatments, with moisture content ranging from 74.8 to 75.0%, crude protein from 17.8 to 18.2%, crude lipid from 2.89 to 3.15%, and crude ash from 3.62 to 3.80%. Similarly, there were no significant differences in cumulative survival rates during lethal temperature exposure between the GABA-supplemented groups and the control group, with an average of 28.5 ± 4.6%. Additionally, GABA inclusion did not significantly alter plasma-free amino acid profiles, antioxidant enzyme activities, or immune functions (p > 0.05). However, temperature significantly reduced the levels of superoxide dismutase (SOD) from 3.34 ± 0.17 to 2.29 ± 0.36 µg/mL and increased the levels of glutamate oxaloacetate transaminase (GOT) from 17.1 ± 0.8 to 46.3 ± 6.2 U/L, glutamate pyruvate transaminase (GPT) from 14.4 ± 0.6 to 30.2 ± 2.1 U/L, glucose (GLU) from 13.3 ± 0.5 to 68.7 ± 7.7 mg/dL, total protein (TP) from 2.94 ± 0.00 to 3.21 ± 0.1 g/dL, and cortisol from 5001 ± 147 to 6395 ± 194 ng/mL. Furthermore, no significant changes were observed in the expression of key stress-related genes, including heat shock proteins (hsp60, hsp70, and hsp90) and the warm water acclimation-related gene wap65. This study establishes the safety of GABA as a dietary inclusion for olive flounder and highlights its potential to enhance stress resilience in aquaculture. However, the effectiveness of GABA-based interventions could depend on critical factors such as dosage, stress duration, and species-specific responses. Our findings highlight the need for further research to optimize GABA inclusion strategies, particularly with consideration for long-term physiological impacts. Full article

Efficient farm practices are crucial for livestock health and performance, and cold stress is a major challenge for cattle in winter. This study aimed to preliminarily investigate the effects of cold and warm water intake in winter on the growth performance, thermal stress indicators, serum hormones and metabolites, rumen fermentation parameters, rumen fiber degrading enzyme, and rumen microflora of yellow cattle during winter. Eight Wandong Bulls (Bos taurus) were divided into two groups: group C, which received cold water (6.36 ± 1.99 °C), and group E, which received warm water (32.00 ± 3.12 °C) for 30 d. The results showed that warm water intake significantly increased ADG (p = 0.024) and DMI (p = 0.046) and decreased (p = 0.047) the ratio of feed intake to weight gain. Furthermore, the heat production, respiratory rate, surface temperature, and rectal temperature of cattle did not alter with water temperature, but the heat production value of the bulls increased (29.64 vs. 25.76 MJ/W^0.75 h⁻¹) with cold water intake compared to warm water. The concentrations of thyroxine (p = 0.021), serum urea nitrogen (p = 0.025), and glucose (p = 0.011) increased for the bulls drinking cold water compared to those drinking warm water. The concentrations of NH₃-N (p = 0.048), total VFA (p = 0.010), acetate (p = 0.009), propionate (p = 0.009), cellulase (p < 0.01), and xylanase (p < 0.05) were lower in group C compared to group E. Total bacterial abundance, as well as specific species including Ruminococcus flavus, Ruminococcus albus, and Prevotella ruminicola, were lower (p < 0.05) in group C compared to group E. In conclusion, drinking warm water during winter enhanced growth performance by influencing energy metabolism, regulating serum hormones and metabolites, and modulating ruminal microflora of bulls compared to cold water intake. Full article