The evolution of accessory air-breathing structures is typically associated with reduction of the gills, although branchial ion transport remains pivotal for acid-base and ion regulation. Therefore, ...air-breathing fishes are believed to have a low capacity for extracellular pH regulation during a respiratory acidosis. In the present study, we investigated acid-base regulation during hypercapnia in the air-breathing fish Pangasianodon hypophthalmus in normoxic and hypoxic water at 28-30°C. Contrary to previous studies, we show that this air-breathing fish has a pronounced ability to regulate extracellular pH (pHe) during hypercapnia, with complete metabolic compensation of pHe within 72 h of exposure to hypoxic hypercapnia with CO2 levels above 34 mmHg. The high capacity for pHe regulation relies on a pronounced ability to increase levels of HCO3(-) in the plasma. Our study illustrates the diversity in the physiology of air-breathing fishes, such that generalizations across phylogenies may be difficult.
Micropropagation of Lang Bian ginseng (
Panax vietnamensis
var.
langbianensis
), an endemic medicinal plant, via somatic embryogenesis (SE) and rhizome formation were investigated. Rhizome explants ...disinfected with 0.15% AgNPs for 30 min resulted in the most effective surface disinfection (contamination, necrosis and survival with callus induction of 36.00%, 14.70% and 49.30%, respectively). Moreover, shoot regeneration (45.33%) and the number of shoots (5.2 shoots) from 0.15% AgNPs disinfected- rhizome were significantly higher than those in others after 12 weeks of culture. The leaf was cut transverse thin cell layer (L-tTCL: 1 mm × 5 mm) and petiole cut longitudinally TCL (P-lTCL: 0.5 mm × 10 mm). L-tTCL explant cultured on MS medium supplemented with 7 mg/L NAA gave 100% SE and 32.80 embryos; meanwhile, P-lTCL explants also obtained 100% SE and 51.80 embryos in 1 mg/L 2,4-D treatment. Adventitious root formation and callus induction were also observed in the auxin-supplemented treatments. In addition, 12-week-old secondary somatic embryos, mainly cotyledonary stage, were obtained from the primary somatic embryo cultured on 1/2 MS medium supplemented with 1 mg/L 2,4-D. Plantlets derived from secondary embryos grew well with 63.34% rhizome formation, 1.27 cm in rhizome length and 0.65 cm in rhizome diameter. Meanwhile, plantlets derived from adventitious shoots only induced adventitious roots and callogenesis after 20 weeks of culture. The analysis of saponins by HPLC method showed that twenty-week-old in vitro rhizomes had Rg1, Rd and Rb1.
Key message
(1) Silver nanoparticles were effective in rhizome surface disinfection. (2) Primary and secondary somatic embryogenesis in Lang Bian ginseng. (3) Rhizome formation with ginsenoside accumulation.
This study describes a pickup and delivery vehicle routing problem, considering time windows in reality. The problem of tractor truck routes is formulated by a mixed integer programming model. ...Besides this, three algorithms - a guided local search, a tabu search, and simulated annealing - are proposed as solutions. The aims of our study are to optimize the number of internal tractor trucks used, and create optimal routes in order to minimize total logistics costs, including the fixed and variable costs of an internal vehicle group and the renting cost of external vehicles. Besides, our study also evaluates both the quality of solutions and the time to find optimal solutions to select the best suitable algorithm for the real problem mentioned above. A novel mathematical model is formulated by OR tools for Python. Compared to the current solution, our results reduced total costs by 18%, increased the proportion of orders completed by internal vehicles (84%), and the proportion of orders delivered on time (100%). Our study provides a mathematical model with time constraints and large job volumes for a complex distribution network in reality. The proposed mathematical model provides effective solutions for making decisions at logistics companies. Furthermore, our study emphasizes that simulated annealing is a more suitable algorithm than the two others for this vehicle routing problem.
This study investigates the suitability of Spirulina-Ogawa-Terui (SOT) culture media with various nutrition concentrations for the laboratory growth of salt-tolerant Spirulina platensis ST. Among the ...four saltwater mediums, 25% SOT media (42‰ salinity) demonstrated a satisfactory performance, with maximum absorbance at a wavelength 556 nm reading of 0.76. After 15 cultivation days, the protein, carbohydrate, lipid, phycocyanin, chlorophyll a, and carotenoid contents reached 48.73%, 22.14%, 7.32%, 10.23%, 0.53%, and 0.12% of the dry cell weight (DCW), respectively. The growth of S. platensis ST is influenced by the culture medium with a salinity of 13‰ and 52‰, as well as different nutrient compositions. Transcriptional sequencing revealed that the response of S. platensis ST to salt stress was mainly expressed by regulating the gene expression involved in metabolic pathways such as photosynthesis and signaling transduction. Under nutritional and salt stress, S. platensis ST responds by modulating the gene expression involved in the synthesis of vital molecules, for example, growth regulators and adenosine triphosphate (ATP) producers. In conclusion, this study provides an insight into enhancing the ability of S. platensis to tolerate salt stress. The findings indicate that future efforts in algal-based cultivation research in seawater should focus on increasing the productivity to develop a sustainable industry for biomass production.
Today microalgae represent a viable alternative source of squalene for commercial application. The species Schizochytrium mangrovei, a heterotrophic microalga, has been widely studied and provides a ...high amount of squalene, polyunsaturated fatty acids and has good profiles for biodiesel production. Our work was aimed at examining the squalene contents in Vietnam's heterotrophic marine microalga S. mangrovei PQ6 biomass and residues of the biodiesel process from this strain. Thin-layer chromatography and high-performance liquid chromatography (HPLC) methods were successfully applied to the determination of squalene in S. mangrovei PQ6. The squalene content and production of S. mangrovei PQ6 reached 33.00 ± 0.02 and 33.04 ± 0.03 mg g−1 of dry cell weight; and 0.992 g L−1 and 1.019 g L−1 in 30 and 150 L bioreactors, respectively after 96 h of fermentation. In addition, squalene was also detected in spent biomass (approximately 80.10 ± 0.03 mg g−1 of spent biomass) from the S. mangrovei PQ6 biodiesel production process. The structure of squalene in residues of the biodiesel process was confirmed from its nuclear magnetic resonance spectra. The results obtained from our work suggest that there is tremendous potential in the exploitation of squalene as a value-added by-product besides biodiesel from S. mangrovei PQ6 to reduce biodiesel price.
Schizochytrium mangrovei strain PQ6 was investigated for coproduction of docosahexaenoic acid (C22: 6ω‐3, DHA) and squalene using a 30‐L bioreactor with a working volume of 15 L under various batch ...and fed‐batch fermentation process regimes. The fed‐batch process was a more efficient cultivation strategy for achieving higher biomass production rich in DHA and squalene. The final biomass, total lipid, unsaponifiable lipid content, and DHA productivity were 105.25 g · L−1, 43.40% of dry cell weight, 8.58% total lipid, and 61.66 mg · g−1 · L−1, respectively, after a 96 h fed‐batch fermentation. The squalene content was highest at 48 h after feeding glucose (98.07 mg · g−1 of lipid). Differences in lipid accumulation during fermentation were correlated with changes in ultrastructure using transmission electron microscopy and Nile Red staining of cells. The results may be of relevance to industrial‐scale coproduction of DHA and squalene in heterotrophic marine microalgae such as Schizochytrium.
Little is known about the anxiety of hospital social workers during the COVID-19 pandemic and their response to social work administration in mental health care for hospital social workers. This ...study investigated anxiety among hospital social workers in Ho Chi Minh City, Vietnam during the COVID-19 pandemic. A cross-sectional study was conducted in August 2021 among 577 hospital social workers. The study results show that 67.0% of hospital social workers experienced normal and mild anxiety levels, 19.5% reported a moderate level of anxiety, and 13.5% had a severe level of anxiety. In the regression models, significant factors related to anxiety levels among hospital social workers were hospital class, gender, type of housemate, and job satisfaction during the COVID-19 pandemic. Suggestions for social work administration are also discussed.
Aim
This study explored knowledge, experience and attitudes of health professionals towards early essential newborn care and skin‐to‐skin contact following Caesarean sections in a tertiary hospital ...in Central Vietnam.
Method
We conducted a cross‐sectional descriptive study using an anonymous questionnaire in March 2016. Health professionals from obstetrics, anaesthesiology and neonatology departments were surveyed.
Results
All of the 204 surveys were returned, accounting for 82% of total staff involved in the care for women and newborns with Caesarean sections. Correct knowledge of early essential newborn care was lowest among anaesthesiology staff. Health professionals reported that ≥90% of Caesarean section births they attended in the preceding week had skin‐to‐skin contact. Approximately 16% obstetricians, 71% midwives, 49% anaesthesiology and 76% neonatology staff considered the current frequency of skin‐to‐skin contact to be about right. The remainder considered the current rate too high. All professional groups identified the main difficulties of conducting skin‐to‐skin contact as the temperature in the operating theatre and the need for additional staff. Other concerns included increasing the risk of the baby of falling off, prolonging the operation and difficulty to monitor mothers.
Conclusion
The study identifies issues where improvements can be made in the implementation of skin‐to‐skin contact following Caesarean sections.
The slider crank mechanism (SCM) widely applied in intrustry and life. The more acceleration increases, the more unstable the mechanical system. The more friction increases, the faster the mechanical ...system wears, and the higher the stress increases, the faster the mechanical system is destroyed. To minimize the influence of the above factors on the slider crank mechanism, the study simulated and analyzed the affect of geometrical parameters on the performance of the design model based on analytical methods finite elements (FEA) using ANSYS software. The geometrical parameters of the design model are optimized through a multi-criteria decision optimization model. The weighting factor of each metric was firm by the entropy method, and the multi-objective optimization was transformed into a single objective using the TOPSIS-based grey relational grade (GrT-TOPSIS) comprehensive evaluation method to achieve the optimal combination of process parameters. This new combination method was first proposed to be applied to the SCM. Experimental results show that all results are consistent with each other. The optimal variables of the inertial acceleration, maximum principal stress, and contact force are 4.4062 m/s
2
, 1.9425 MPa, and 19,718 N, respectively. The deviation between the predictor and the optimal variable of GRG is less than 4%.
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