Rheotaxis facilitates upstream navigation of mammalian sperm cells

A major puzzle in biology is how mammalian sperm determine and maintain the correct swimming direction during the various phases of the sexual reproduction process. Whilst chemotaxis is assumed to dominate in the immediate vicinity of the ovum, it is unclear which biochemical or physical cues guide spermatozoa on their long journey towards the egg cell. Currently debated mechanisms range from peristaltic pumping to temperature sensing (thermotaxis) and direct response to fluid flow variations (rheotaxis), but little is known quantitatively about their relative importance. Here, we report the first quantitative experimental study of mammalian sperm rheotaxis. Using microfluidic devices, we investigate systematically the swimming behavior of human and bull sperm over the whole range of physiologically relevant shear rates and viscosities. Our measurements show that the interplay of fluid shear, steric surface-interactions and chirality of the flagellar beat leads to a stable upstream spiraling motion of sperm cells, thus providing a generic and robust rectification mechanism to support mammalian fertilisation. To rationalise these findings, we identify a minimal mathematical model that is capable of describing quantitatively the experimental observations. The combined experimental and theoretical evidence supports the hypothesis that the shape and beat patterns of mammalian sperm cells have evolved to optimally exploit rheotaxis for long-distance navigation.Comment: 18 pages, 4 figures, supplementary information available at eLifesciences.or

Effects of centrifugal stress on cell disruption and glycerol leakage from Dunaliella salina

Dunaliella salina accumulates large amounts of intracellular glycerol in response to the increases in salt concentration, thus is a potential source for producing fuel grade glycerol as an alternative to biodiesel-derived crude glycerol. D. salina lacks a cell wall; therefore the mode of harvesting Dunaliella cells is critical to avoid cell disruption caused by extreme engineering conditions. This study explored cell disruption and glycerol leakage of D. salina under various centrifugal stresses during cell harvesting. Results show a centrifugal g-force lower than 5000 g caused little cell disruption, while a g-force higher than 9000 g led to ~40 % loss of the intact cells and glycerol yields from the recovered algal pellets. Theoretical calculations of the centrifugal stresses that could rupture Dunaliella cells were in agreement with the experimental results, indicating optimisation of centrifugation conditions is important for recovering intact cells of from D. salina enriched in glycerol

ASSOCIATION BETWEEN TYPE 2 DIABETES MELLITUS AND COVID-19 SEVERITY: A LITERATURE REVIEW

Objective: Globally, there is a rise in the frequency of type 2 diabetes mellitus and diabetes is severe co-morbidity in COVID-19 patients. We conducted a review and evaluated the already documents reports for the relationship among diabetes and COVID-19. Methods: Full text was retrieved using PubMed database and Google Scholar using the key phrases ‘COVID-19’, ‘SARS-CoV-2’, ‘diabetes’. Results: The review outcome shows that the COVID-19 severity seems to be greater among patients with diabetes as comorbidity. So, strict glycemic control is imperative in patients infected with COVID-19. Conclusions: Thus, world-wide diabetes burden and COVID-19 pandemic must be deliberated as diabetes increases the COVID-19 severity. Established on this, it is precise significant to follow specific treatment protocols and clinical management in COVID-19 patients affected with diabetes to prevent morbidity and mortality

Silicon Carbide-Coated Ceramic Membrane Bioreactor for Sustainable Water Purification

In the present study, a submerged ceramic membrane bioreactor was used to effectively treat industrial wastewater. The outcome of membrane coatings on the efficacy of the membrane was investigated using a silicon carbide (SiC) coating. The flux data obtained from the study were fitted into two mathematical models, namely, the standard pore blocking model (SPBM) and the complete pore plugging model (CPPM) in order to determine the fouling mechanism. It was observed that the SPBM fit with a minimum coefficient of regression of 0.95, suggesting that particles retained on the pore walls were smaller than the average size of membrane pores. An increase in dissolved oxygen (DO) of up to 225% was noted. The significant improvement of the water quality in terms of DO, chemical oxygen demand (COD) and turbidity of coated membrane emphasizes the fact that the membrane coating increases the efficacy of water treatment in membrane bioreactors

Enhancement in CO₂ Adsorption on Hydrotalcite-based Material by Novel Carbon Support Combined with K₂CO₃ Impregnation

In recent years, a great deal of interest has been shown for high-temperature adsorption of CO₂ on hydrotalcite-like compounds (HTlcs). Numerous efforts have been undertaken to enhance the CO₂ capture property of HTlcs, including alkali-metal impregnation, use of support materials, and modification of chemical composition. The present work demonstrates the applicability of coal-derived graphitic material (CGM) as an effective support for neat as well as K₂CO₃-promoted Mg–Al HTlc, enhancing the CO₂ adsorption capacity. Both surface area and basic site density affect the adsorption capacity. The K₂CO₃-promoted CGM-supported Mg–Al HTlc exhibited a fresh adsorption capacity of 1.10 mmol g^–1 at 300 °C under a total pressure of 1 bar. After the initial drop, it maintained an average working capacity of 0.42 mmol g^–1 during nine cycles of adsorption–desorption in the temperature range of 300–400 °C. The Yoon–Nelson kinetic model fit well with the experimental data

Acute pancreatitis associated with the antibiotic levofloxacin: A rare case report

Key Clinical Message Drug‐induced acute pancreatitis is a potentially ignored diagnosis that must be precisely valued. Drug‐induced acute pancreatitis can be considered the third common cause of acute pancreatitis after ruling out alcohol and gallstones. Levofloxacin belongs to a class of fluoroquinolone antibiotics used for treating various infections. Besides photosensitivity and liver toxicity, levofloxacin can induce acute pancreatitis, although rarely described. We highlight a case of acute pancreatitis in a female induced by levofloxacin. She presented with typical signs and symptoms of acute pancreatitis and had been taking levofloxacin for urinary tract infections for the last 3 days. After ruling out all other possible causes, her clinical picture, laboratory results, and imaging findings confirmed acute pancreatitis induced by levofloxacin