scholarly journals Rapidly Pulsed Pumping Accelerates Remediation in A Vertical Circulation Well Model

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1423 ◽  
Author(s):  
David Kahler
Keyword(s):  
Groundwater Remediation ◽  
Sudden Increase ◽  
Vertical Circulation ◽  
Duration Of Treatment ◽  
Capital Costs ◽  
Pulsed Flow ◽  
Dead End ◽  
Sudden Decrease ◽  
Dynamics Models ◽  
Pulsed Pumping

One factor that slows groundwater remediation is the sequestration of contaminant in dead-end pores, that is, pores that are not flushed through by flow through the aquifer. Furthermore, rebound of apparently remediated aquifers can occur as a result of the eventual release of the contaminant trapped in these dead-end pores. Since the operational costs generally outweigh the capital costs of a remediation project, reduction of the duration of treatment should reduce the overall cost of the average remediation. It has been shown that a rapidly pulsed flow can increase the mixing between dead-end and well-connected pores through computational fluid dynamics models with idealized pore geometry and column tests. A rapidly pulsed flow induces a deep sweep upon a sudden increase in velocity and a vortex ejection upon a sudden decrease in velocity that substantially accelerates the remediation of contaminant from these dead-end pores. To examine rapidly pulsed pumping in a more realistic configuration, a model vertical circulation well was constructed. The porous medium was well-sorted crushed glass to minimize sorption. Removal of a fluorescent dye, which represents a dissolved contaminant, under a rapidly pulsed flow was compared to a steady flow. The modeled well revealed accelerated removal of dissolved contaminants under a rapidly pulsed flow.

scholarly journals CHEMICAL TRANSMISSION AND ADAPTATION

1957 ◽  
Vol 40 (4) ◽  
pp. 533-545 ◽  
Author(s):  
Ernst Florey
Keyword(s):  
Sensory Neurons ◽  
Time Course ◽  
Silent Period ◽  
Nerve Fibers ◽  
Sudden Increase ◽  
Impulse Frequency ◽  
Factor I ◽  
Central Neurons ◽  
Frequency Level ◽  
Sudden Decrease

Acetylcholine and factor I appear to be transmitter substances of excitatory and inhibitory regulatory nerve fibers supplying the sensory neurons of stretch receptor organs of the crayfish. Sudden application of a low concentration of acetylcholine causes the impulse frequency to jump to a peak value. But immediately the frequency falls again and gradually reaches a steady state which is not far above the previous frequency level. If the acetylcholine is now withdrawn there follows a silent period after which the frequency returns to its original level. The time course of these events is identical with that of adaptations to sudden increase or decrease of stretch. Factor I in sufficiently low concentrations causes an immediate fall in impulse frequency (silent period) which is followed by a return to a value near the previous frequency level. Withdrawal of factor I is followed by excitation and again return of the frequency to the rate measured before the application of factor I. The time course of these phenomena is identical with that of adaptations to sudden decrease and increase of stretch. It is suggested that adaptation may be a property not only of sensory neurons but of neurons in general and that even central neurons may be considered as receptor neurons inasmuch as they respond to chemically transmitted excitatory and inhibitory stimuli.

Influence of wall suction on the organized motion in a turbulent boundary layer

1988 ◽  
Vol 190 ◽  
pp. 217-240 ◽  
Author(s):  
R. A. Antonia ◽  
L. Fulachier ◽  
L. V. Krishnamoorthy ◽  
T. Benabid ◽  
F. Anselmet
Keyword(s):  
Boundary Layer ◽  
Heated Surface ◽  
Local Maximum ◽  
Average Frequency ◽  
Convection Velocity ◽  
Water Tunnel ◽  
Sudden Increase ◽  
Wall Suction ◽  
Low Speed Streaks ◽  
Sudden Decrease

The effect of wall suction on the organized motion of a tubulent boundary layer is examined experimentally both in a wind tunnel and in a water tunnel. In the windtunnel boundary layer, which developed over a slighly heated surface, temperature fluctuations were simultaneously obtained at several points, aligned in either the x (streamwise) or y (normal to the wall) direction. The temperature traces reveal the existence of two spatially coherent events, characterized either by a sudden decrease (cooling) or by a sudden increase (heating) of temperature. Estimates are presented for the average convection velocity, and average frequency of these events. The average convection velocity of ‘coolings’ is about 15% larger than that of ‘heatings’, the velocity of both events exhibiting an important local maximum in the buffer region. Near the wall, the convection velocity of both events is increased slightly by suction while their average frequency is reduced by suction. Away from the wall, the average inclination of ‘coolings’ and ‘heatings’ is about 40° without suction; suction does not alter the inclination of ‘coolings’ but increases that of ‘heatings’ to about 50°. Visualizations in the water tunnel indicate that suction increases the stability and the longitudinal coherence of low-speed streaks. They also show that suction reduces the average frequency of dye ejections into the outer layer.

scholarly journals HYDROSTATIC PRESSURE AND TEMPERATURE IN RELATION TO STIMULATION AND CYCLOSIS IN NITELLA FLEXILIS

1942 ◽  
Vol 25 (6) ◽  
pp. 855-863 ◽  
Author(s):  
E. Newton Harvey
Keyword(s):  
High Pressure ◽  
Hydrostatic Pressure ◽  
Temperature Effect ◽  
Low Temperatures ◽  
Pressure Effect ◽  
Sudden Increase ◽  
Optimum Temperature ◽  
Luminous Bacteria ◽  
Sudden Decrease ◽  
Nitella Flexilis

Nitella flexilis cells are not stimulated to "shock stoppage" of cyclosis by suddenly evacuating the air over the water or on sudden readmission of air, or on suddenly striking a piston in the water-filled chamber in which they are kept with a ball whose energy is 7.6 joules, provided the Nitella cell is not moved by currents against the side of the chamber. Sudden increases in hydrostatic pressure from zero to 1000 lbs. or 0 to 5000 lbs. per square inch or 5000 to 9000 lbs. per square inch usually do not stimulate to "shock stoppage" of cyclosis, but some cells are stimulated. Sudden decreases of pressure are more likely to stimulate, again with variation depending on the cell. In the absence of stimulation, the cyclosis velocity at 23°C. slows as the pressure is increased in steps of 1000 lbs. per square inch. In some cells a regular slowing is observed, in others there is little slowing until 4000 to 6000 lbs. per square inch, when a rapid slowing appears, with only 50 per cent to 30 per cent of the original velocity at 9000 lbs. per square inch. The cyclosis does not completely stop at 10000 lbs. per square inch. The pressure effect is reversible unless the cells have been kept too long at the high pressure. At low temperatures (10°C.) and at temperatures near and above (32°–38°C.) the optimum temperature for maximum cyclosis (35–36°C.) pressures of 3000 to 6000 lbs. per square inch cause only further slowing of cyclosis, with no reversal of the temperature effect, such as has been observed in pressure-temperature studies on the luminescence of luminous bacteria. Sudden increase in temperature may cause shock stoppage of cyclosis as well as sudden decrease in temperature.

scholarly journals Perioperative Anesthetic Management in Preterm 12 Days Infants with Giant Meningoencephalocele at Mid Occipital and Secondary Trigonocephaly

2021 ◽  
Vol 4 (4) ◽  
Author(s):  
Kirby Saputra ◽  
◽  
Radian Ahmad Halimi
Keyword(s):  
Intracranial Pressure ◽  
Anesthetic Management ◽  
Fetal Distress ◽  
Anesthetic Techniques ◽  
Sudden Increase ◽  
Neural Element ◽  
Preoperative Preparation ◽  
Focal Neurological Deficit ◽  
Occipital Encephalocele ◽  
Sudden Decrease

Introduction: A meningoencephalocele is herniation of neural element along with meninges through a congenital defect in cranium. The incidence of encephalocele is approximately 1/5000 live births; occipital encephalocele is more common in females than males. It is called as giant meningoencephalocele when the head is smaller than the meningoencephalocele. These giant meningoencephaloceles harbor a large amount of cerebrospinal fluid (CSF) and brain tissue, so there occur various surgical challenges and anesthetic challenges in positioning and intubation. Case: A 12 days neonate was consulted to the neurosurgery department with complaints of large swelling over the back of head and difficulty in feeding. She was diagnosed with ventriculomegaly and meningoencephalocele since 32-33 pregnancy. The swelling was small at the time of birth, but it gradually increased in size. The child was born by section caesarean because of fetal distress and meningoenchepalocele. The neonate current weight was 3.195 grams with Post Conceptional Age (PCA) 35-36 weeks. On examination, the patient large spherical swelling was present over occipital region and there was no head control. The patient was active, conscious with no impression of focal neurological deficit. Systemic examination was unremarkable. The head circumference was 30 cm and circumference of occipital swelling was 40 cm. Potential problems in this patient include preoperative preparation and optimization of general condition, difficulty in positioning the patient, difficult airway (intubation), periodic apnea and potential hemodynamic disturbances and a sudden decrease in intracranial pressure during cele resection. Conclusion: Perioperative management in this case started from preoperative to postoperative evaluation. Preoperative preparation in anticipation of airway difficulties and communication with the operator is very important. Appropriate anesthetic techniques should aim to maintain stable hemodynamics and oxygenation and prevent a sudden increase or decrease in intracranial pressure.

A reactor model for pulsed pumping groundwater remediation

2004 ◽  
Vol 38 (18) ◽  
pp. 3869-3880 ◽  
Author(s):  
C.M. Tenney ◽  
C.M. Lastoskie ◽  
M.J. Dybas
Keyword(s):  
Groundwater Remediation ◽  
Reactor Model ◽  
Pulsed Pumping

scholarly journals Perioperative Anesthetic Management in Preterm 12 Days Infants with Giant Meningoencephalocele at Mid Occipital and Secondary Trigonocephaly

2021 ◽  
Author(s):  
Kirby Saputra ◽  
Radian Ahmad Halimi
Keyword(s):  
Intracranial Pressure ◽  
Anesthetic Management ◽  
Fetal Distress ◽  
Anesthetic Techniques ◽  
Sudden Increase ◽  
Neural Element ◽  
Preoperative Preparation ◽  
Focal Neurological Deficit ◽  
Occipital Encephalocele ◽  
Sudden Decrease

Introduction: A meningoencephalocele is herniation of neural element along with meninges through a congenital defect in cranium. The incidence of encephalocele is approximately 1/5000 live births; occipital encephalocele is more common in females than males. It is called as giant meningoencephalocele when the head is smaller than the meningoencephalocele. These giant meningoencephaloceles harbor a large amount of cerebrospinal fluid (CSF) and brain tissue, so there occur various surgical challenges and anesthetic challenges in positioning and intubation. Case: A 12 days neonate was consulted to the neurosurgery department with complaints of large swelling over the back of head and difficulty in feeding. She was diagnosed with ventriculomegaly and meningoencephalocele since 32-33 pregnancy. The swelling was small at the time of birth, but it gradually increased in size. The child was born by section caesarean because of fetal distress and meningoenchepalocele. The neonate current weight was 3.195 grams with Post Conceptional Age (PCA) 35-36 weeks. On examination, the patient large spherical swelling was present over occipital region and there was no head control. The patient was active, conscious with no impression of focal neurological deficit. Systemic examination was unremarkable. The head circumference was 30 cm and circumference of occipital swelling was 40 cm. Potential problems in this patient include preoperative preparation and optimization of general condition, difficulty in positioning the patient, difficult airway (intubation), periodic apnea and potential hemodynamic disturbances and a sudden decrease in intracranial pressure during cele resection. Conclusion: Perioperative management in this case started from preoperative to postoperative evaluation. Preoperative preparation in anticipation of airway difficulties and communication with the operator is very important. Appropriate anesthetic techniques should aim to maintain stable hemodynamics and oxygenation and prevent a sudden increase or decrease in intracranial pressure.

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