scholarly journals Histopathological evaluation of formalin toxicity in Arapaima gigas (Arapaimidae), the giant fish from Amazon

2018 ◽  
Vol 38 (6) ◽  
pp. 1015-1025
Author(s):  
Sanny M. Andrade-Porto ◽  
Cleverson A. Ramos ◽  
Rosemary Roque ◽  
Elizabeth G. Affonso ◽  
José F.M. Barcellos ◽  
...  
Keyword(s):  
Sublethal Effects ◽  
Clinical Signs ◽  
Lethal Concentration ◽  
Histopathological Analysis ◽  
Behavioral Alterations ◽  
Mean Values ◽  
Short Term Exposure ◽  
Arapaima Gigas ◽  
Significant Difference ◽  
Hydrodynamic Equilibrium

ABSTRACT: This study aimed to determine the lethal concentration and the structural and ultra-structural effects caused by the formalin exposure on juveniles of Arapaima gigas. Ninety fish (60.1± 2.5g and 20.2±0.9cm) were exposed to 0, 22, 44, 66, 88 and 110mg L-1 in order to determine the lethal concentration (LC50-96h) that was 36.4mg L-1 of formalin. Sublethal effects were evaluated using histopathological analysis on the gills and assessment of behavioral alterations and clinical signs. The LC50 of formalin for 24, 48 and 72h was 88.3, 64.7 and 56.8mg L-1 respectively. Clinical signs and behavioral changes were found: erratic swimming, lethargy, crowding on the water surface, loss of hydrodynamic equilibrium, spasms and agonistic confrontation, which were observed only at 88 and 110mg L-1. The histological alteration index (HAI) showed that 66, 88 and 100mg L-1 presented significant difference (p<0.05) in relation to unexposed fish, indicating that moderate damage to the gills of fish exposed to formalin had occurred. The mean values of alteration (MVA) for 22, 44, 66, 88 and 110mg L-1 were 1.14, 1.29, 1.51, 1.53 and 1.60 respectively, and differences in this index were only observed with 110 mgL-1 of formalin. It is therefore possible to conclude that sublethal concentrations of formalin (22.0mg L-1) did not compromise the health of juveniles of A. gigas. Finally, concentrations greater than to LC50-96h may be carefully used for short-term exposure, since the MVA for all concentrations tested only indicated localized lesions that did not compromise gills functionality of exposed fish.

Effetti dell'ipocapnia e dell'ipercapnia sul flusso liquorale acqueduttale e sul flusso ematico nel seno sagittale superiore. Studio quantitativo con Cine-RM contrasto di fase in soggetti normali

1997 ◽  
Vol 10 (2_suppl) ◽  
pp. 43-45
Author(s):  
M. Santoni ◽  
M. Mascalchi ◽  
M. Cellerini ◽  
A. Cuttano ◽  
G. Dal Pozzo
Keyword(s):  
Flow Velocity ◽  
Cardiac Cycle ◽  
Mean Flow ◽  
Csf Flow ◽  
Flow Area ◽  
Sagittal Sinus ◽  
Cine Mr ◽  
Plastic Bag ◽  
The Mean ◽  
Hydrodynamic Equilibrium

The aqueductal CSF and superior sagittal sinus (SSS) blood flow were quantified in 9 healthy volunteers using a Phase Contrast Cine MR technique with retrospective cardiac gating and velocity of encoding of 10 and 30 cm/s. All subjects were examined in basal conditions, during hypocapnia determined by sustained hyperventilation and during hypercapnia (>5%) obtained with rebreathing in a plastic bag. In basal conditions, the aqueductal CSF flow area showed a mean increase of 24% synchronous with the cerebral systole, whereas variations of the SSS flow area during the cardiac cycle were negligible (>9%). The mean flow velocity and volume in the SSS were 11.7 cm/s and 236 ml/min. Mean peak systolic and diastolic aqueductal CSF velocity were + 2 cm/s and −2 cm/s. Hypocapnia determined in all but one subjects a decrease of the SSS blood and aqueductal CSF velocities. During hypocapnia a decrease of the aqueductal CSF flow area was also observed. Hypercapnia was associated with a decrease of the SSS flow velocity in 3 subjects and to minor changes in the remaining 6 subjects. Hypercapnia determined an increase (up to 30%) in the peak systolic and diastolic aqueductal CSF flow velocity in 3 subjects, negligible changes in 5 subjects and a decrease of the same parameters in one subject. The aqueductal CSF flow area was decreased in 8 subjects during hypercapnia. Hypocapnia and hypercapnia are relatively simple tests which can be used to modify the intracranial hydrodynamic equilibrium in healthy subjects. Further investigations are however needed before their application to the study of intracranial hydrodynamics in patients with hydrocephalus.

A Method to Calculate Resistance of Ship Taking the Effect of Dynamic Sinkage and Trim and Viscosity of Fluid

2011 ◽  
Vol 121-126 ◽  
pp. 1849-1857
Author(s):  
Chao Bang Yao ◽  
Wen Cai Dong
Keyword(s):  
Boundary Layer ◽  
Free Surface ◽  
Flow Field ◽  
Indirect Method ◽  
Free Surface Flow ◽  
Field Resistance ◽  
Surface Flow ◽  
Equilibrium Equations ◽  
Sinkage And Trim ◽  
Hydrodynamic Equilibrium

A method is presented to calculate the resistance of a ship taking the effect of sinkage & trim and viscosity of fluid. The free surface flow field is evaluated by solving RANS equations with VOF method. The sinkage and trim are computed by hydrodynamic equilibrium equations. The method can be divided into direct and indirect method according to the way to calculate trim of ship. The software Fluent is used to implement this method. With dynamic mesh being used, the position of a ship is updated by the motion of “ship + boundary layer” grid zone. The present methods have been applied to the INSEAN2340 hull for different Froude numbers and are found to be efficient for evaluating the flow field, resistance, sinkage and trim.

scholarly journals On the hydrodynamic equilibrium of a rod in a lattice fluid

2000 ◽  
Vol 33 (26) ◽  
pp. 4725-4740 ◽  
Author(s):  
Pablo A Ferrari ◽  
Christian Maes ◽  
Laura Ramos ◽  
Frank Redig
Keyword(s):  
Lattice Fluid ◽  
Hydrodynamic Equilibrium

Non-axisymmetric magneto- hydrodynamic equilibrium in the presence of internal magnetic islands and external magnetic perturbation coils

2013 ◽  
Vol 55 (12) ◽  
pp. 125009 ◽  
Author(s):  
B J Tobias ◽  
M E Austin ◽  
I G J Classen ◽  
C W Domier ◽  
N C Luhmann ◽  
...  
Keyword(s):  
Magnetic Islands ◽  
Magnetic Perturbation ◽  
Hydrodynamic Equilibrium

scholarly journals Acoustic streaming vortices enable contactless, digital control of droplets

2020 ◽  
Vol 6 (24) ◽  
pp. eaba0606 ◽  
Author(s):  
Peiran Zhang ◽  
Chuyi Chen ◽  
Xingyu Su ◽  
John Mai ◽  
Yuyang Gu ◽  
...  
Keyword(s):  
Digital Control ◽  
Acoustic Streaming ◽  
Lab On A Chip ◽  
Cross Contamination ◽  
Basic Logic ◽  
Electrical Signals ◽  
Electrical Control ◽  
Logic Operations ◽  
Contact Free ◽  
Hydrodynamic Equilibrium

Advances in lab-on-a-chip technologies are driven by the pursuit of programmable microscale bioreactors or fluidic processors that mimic electronic functionality, scalability, and convenience. However, few fluidic mechanisms allow for basic logic operations on rewritable fluidic paths due to cross-contamination, which leads to random interference between “fluidic bits” or droplets. Here, we introduce a mechanism that allows for contact-free gating of individual droplets based on the scalable features of acoustic streaming vortices (ASVs). By shifting the hydrodynamic equilibrium positions inside interconnected ASVs with multitonal electrical signals, different functions such as controlling the routing and gating of droplets on rewritable fluidic paths are demonstrated with minimal biochemical cross-contamination. Electrical control of this ASV-based mechanism allows for unidirectional routing and active gating behaviors, which can potentially be scaled to functional fluidic processors that can regulate the flow of droplets in a manner similar to the current in transistor arrays.

scholarly journals Hydrodynamic Equilibrium Simulation and Shut-in Time Optimization for Hydraulically Fractured Shale Gas Wells

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 961
Author(s):  
Fei Wang ◽  
Qiaoyun Chen ◽  
Yingqi Ruan
Keyword(s):  
Shale Gas ◽  
Gas Production ◽  
Fluid Loss ◽  
Hydraulic Fractures ◽  
Hydraulic Pressure ◽  
Gas Wells ◽  
Fracturing Fluid ◽  
Equilibrium Time ◽  
Chemical Osmosis ◽  
Hydrodynamic Equilibrium

Post-fracturing well shut-in is traditionally due to the elastic closure of hydraulic fractures and proppant compaction. However, for shale gas wells, the extension of shut-in time may improve the post-fracturing gas production due to formation energy supplements by fracturing-fluid imbibition. This paper presents a methodology using numerical simulation to simulate the hydrodynamic equilibrium phenomenon of a hydraulically fractured shale gas reservoir, including matrix imbibition and fracture network crossflow, and further optimize the post-fracturing shut-in time. A mathematical model, which can describe the fracturing-fluid hydrodynamic transport during the shut-in process, and consider the distinguishing imbibition characteristics of a hydraulically fractured shale reservoir, i.e., hydraulic pressure, capillarity and chemical osmosis, is developed. The key concept, i.e., hydrodynamic equilibrium time, for optimizing the post-fracturing shut-in schedule, is proposed. The fracturing-fluid crossflow and imbibition profiles are simulated, which indicate the water discharging and sucking equilibrium process in the coupled fracture–matrix system. Based on the simulation, the hydrodynamic equilibrium time is calculated. The influences of hydraulic pressure difference, capillarity and chemical osmosis on imbibition volume, and hydrodynamic equilibrium time are also investigated. Finally, the optimal shut-in time is determined if the gas production rate is pursued and the fracturing-fluid loss is allowable. The proposed simulation method for determining the optimal shut-in time is meaningful to the post-fracturing shut-in schedule.

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