Measurements Of Hydraulic Resistance Research Articles

Characterization and associated pressure-dependent behavior of deposits formed during sterile filtration of mRNA-Lipid nanoparticles

The recent success of mRNA vaccines has generated increased interest in the use of Lipid Nanoparticles (LNPs) for delivery of nucleic acids. The objective of this study was to characterize the deposit formed on the surface of membranes during sterile filtration of mRNA-LNPs using a combination of scanning electron microscopy (SEM), environmental scanning electron microscopy (ESEM), atomic force microscopy (AFM), and hydraulic resistance measurements. The microscopic characterizations showed an amorphous deposit fouling the surface of the filter and blocking the membrane pores. The resistance of the deposit showed an unusual biphasic behavior, increasing at low pressure (consistent with a compressible filtration medium) but decreasing at high pressure, in a reversible manner. The surprising reduction in resistance at high pressure has not previously been identified in the filtration literature. The pressure corresponding to the maximum resistance (Pcritical) was found to be proportional to the inverse of the membrane pore size, as described by the Young-Laplace relationship. The hydraulic resistance measurements and microscopic characterization are consistent with a mechanism whereby an amorphous fouling deposit intrudes through membrane pores at high transmembrane pressures. These results provide important insights into the physical properties of the fouling deposit that governs the sterile filtration of LNPs.

Mechanical Activation of the Phosphorites (Karatau Pool) by using Organic-Mineral Co-Activators for Multicomponent Mineral Fertilizers

Deficiency of mineral fertilizers in the agricultural sector for last 15–20 years has decreased. Therefore with the purpose of partial reduction of this deficiency it was developed a new polycomponent NPK fertilizer, which contains humate and vermiculite. The given fertilizer has been produced from the natural South<br />Kazakhstan raw materials in accordance with an acid-free way. The given article contains the data and physicochemical properties of initial materials prepared on the basis of phosphorite fines of Zhanatas and Chulaktau deposits and sinter return. Characteristics of vermiculite and the internal overburden rocks formed at the mining brown coal on the Lenger deposit are represented. During the experimental research except the above-stated natural raw materials the following substances were used at manufacture of the polycomponent fertilizer: ammonia saltpeter, ammonium sulphate produced by the OJSC “Grodno-Azot”, halurgical potassium chloride produced by “Belaruskaliy” and potassium hydroxide, a chemical reagent of a grade “pure”. The given article contains the data about the chemical composition of initial raw materials and conditions of mechanical-chemical activation of the<br />initial materials at various values of components concentration, temperature and time at the polycomponent fertilizer manufacture. The plan and research results of phosphorite’s activation with the analysis of a disperse structure of nonactivated and activated Zhanatas phosphorite are represented. The determination of nonactivated and activated phosphorites specific surface was performed with use of a device PSH-8A according to the method based on the measurement of hydraulic resistance<br />of a powder material’s layer at filtration of an air low-pressure stream.

Experimental Investigation of Hydraulics and Lateral Mixing for Helical-Cruciform Fuel Rod Assemblies

In order to significantly increase the power density of light water reactors (LWRs), the authors propose the helical-cruciform (HC) fuel rod assembly as an alternative to traditional fuel geometry. The HC fuel rod assembly is a self-supporting nuclear fuel configuration consisting of four-petalled, axially twisted fuel rods closely packed against one another in a square array. Within the LWR core, HC fuel would possess several advantages over traditional fuel, potentially allowing for operation at a higher power density. Chief among these advantages are a larger surface-to-volume ratio, improved radial mixing characteristics of the coolant, and a shorter radial heat conduction path in the fuel pellet. In adapting helical rod geometry to the LWR core, the authors identified a shortage of correlations for fluid flow in twisted geometry flow channels, causing uncertainty in modeling studies. This gap was addressed by constructing an experimental facility for the measurement of hydraulic resistance and assembly mixing within a mock bundle of HC fuel rods. The rods were manufactured and tested in 4 × 4 square arrays at twist pitches of 200, 100, and 50 cm. Hydraulic resistance was evaluated by measuring frictional pressure drop over a 1-m length of the assembly. Results showed a higher pressure drop for the HC rods in comparison to bare cylindrical rods with no spacers, at a given mass flux, but no apparent dependency on twist pitch. However, data indicated that the HC-rod effective hydraulic diameter was only 90% of the expected value given its wetted perimeter and flow area, suggesting a shift from the traditional definition of Dh for this unique shape. Mixing tests used the technique of a hot water tracer injection into the central subchannel of the assembly of room-temperature water. Downstream temperature measurements were used to judge the rate of lateral cross flow within the HC rod bundle. Over 300 tests were analyzed, yielding a best-fit correlation for use with any twist pitch, rod length, or coolant mass flux. Compared to a traditional rod bundle, this correlation implies an enhancement in the intensity of turbulent interchange of 40% brought about by the HC geometry and a 1.6% forced diversion of axial flow per subchannel, per quarter-turn along the rod length. The correlations for hydraulics and cross-flow mixing presented here should reduce the uncertainty in future analysis of this fuel type for high-power-density LWRs.

Shifts in xylem vessel diameter and embolisms in grafted apple trees of differing rootstock growth potential in response to drought

We investigated responses of plant growth rate, hydraulic resistance, and xylem cavitation in scion-rootstock-combinations of Malus domestica L. cv. Honeycrisp scions grafted onto a high-shoot vigor (HSV) rootstock, (semi-dwarfing Malling111), or onto a low-shoot vigor (LSV) rootstock, (dwarfing Budagovsky 9), in response to substrate moisture limitation. Adjustments in xylem vessel diameter and frequency were related to hydraulic resistance measurements for high- versus low- vigor apple trees. We observed a greater tolerance to water deficit in the high-shoot compared to the low-shoot vigor plants under water deficit as evidenced by increased growth in several plant organs, and greater scion anatomical response to limited water availability with ca. 25% increased vessel frequency and ca. 28% narrower current season xylem ring width. Whereas water limitation resulted in greater graft union hydraulic resistance of high-shoot vigor trees, the opposite was true when water was not limiting. The graft union of the low-shoot vigor rootstock exhibited higher hydraulic resistance under well-watered conditions. Scions of high-shoot vigor rootstocks had fewer embolisms at low plant water status compared to scions of low-shoot vigor rootstocks, presumably as a result of large differences in xylem vessel diameter. Our results demonstrated that anatomical differences were related to shifts in hydraulic conductivity and cavitation events, a direct result of grafting, under limited soil water.

The effect of inlet conditions on the air side hydraulic resistance and flow maldistribution in industrial air heaters

Experimental system hydraulic resistance measurements on a scale air heater unit have highlighted the excessive hydraulic resistance of typical industry configurations. Both poor header inlet conditions and large header expansion angles are shown to contribute to system hydraulic resistance magnitudes 20–100% higher than suitable benchmark cases. Typical centrifugal fan system efficiencies well under 80% multiply the system resistance effects resulting in larger fan power penalties. Velocity profile measurements taken upstream and downstream of the test heat exchanger under flow maldistribution conditions provide insight into the flow maldistribution spreading caused by the heat exchanger resistance. The anisotropic resistance of the plate fin-and-tube heat exchanger is shown to result in resistance induced flow dispersion being concentrated in the axis parallel to the plate fins.

Microfluidic parallel circuit for measurement of hydraulic resistance

We present a microfluidic parallel circuit that directly compares the test channel of an unknown hydraulic resistance with the reference channel with a known resistance, thereby measuring the unknown resistance without any measurement setup, such as standard pressure gauges. Many of microfluidic applications require the precise transport of fluid along a channel network with complex patterns. Therefore, it is important to accurately characterize and measure the hydraulic resistance of each channel segment, and determines whether the device principle works well. However, there is no fluidic device that includes features, such as the ability to diagnose microfluidic problems by measuring the hydraulic resistance of a microfluidic component in microscales. To address the above need, we demonstrate a simple strategy to measure an unknown hydraulic resistance, by characterizing the hydraulic resistance of microchannels with different widths and defining an equivalent linear channel of a microchannel with repeated patterns of a sudden contraction and expansion.

Hydraulic resistance measurements combined with electrical or diffusional resistance measurements for determination of pore size in MF membranes

An easy operating, low-cost and fast method for determining the mean pore size of microfiltration (MF) membranes is offered by combining hydraulic resistance measurements with either electrical resistance measurements (ERM) or diffusional resistance measurements (DRM). ERM and DRM allow determination of the structural parameter ε/τ 2 which represents the ratio of membrane porosity to tortuosity factor squared. This parameter being determined, it is then possible to evaluate the mean pore radius from water flux measurements. The mean pore radius can be then determined from water flux measurements by taking into account the tortuosity of pores. This method was applied to MF ceramic membranes with two different pore sizes. Results show that ε/τ 2 values obtained by diffusion and ERM are very close. The mean pore radius determined from this method was found to be in very good agreement with that afforded by mercury intrusion porosimetry (MIP) for both membranes.

The implications of spatial variability in surface seal hydraulic resistance for infiltration in a mound and depression microtopography

Soil surface crusting has a major impact on water infiltration and erosion in many soils. Considerable progress has been made in describing crusting processes and in modelling the impact of crusting on infiltration. Most studies, however, have neglected the high spatial variability in crust characteristics observed in the field. The objective of this experiment was to determine the influence of runoff depth on infiltration rate in the presence of a surface seal varying in hydraulic characteristics with microtopography. The Blosseville silt loam has a low aggregate stability and forms crusts readily. The Villamblain silty clay loam has a greater aggregate stability due to its greater clay and organic matter contents, and it is more resistant to aggregate breakdown processes under rainfall. Samples of the soils were sieved to retain aggregates less than 2.0 cm and packed in 50×50×15 cm soil trays. The trays were surrounded by a 10 cm soil border to compensate for splash loss. After molding the surface into a mound and depression microtopography, the samples were subjected to simulated rainfall at an intensity of 22.8 mm h −1. Hourly measurements of surface roughness showed that the original roughness was smoothed out due to the infilling of depressions by sediments detached from the mounds. For the final hour, runon was added to the top of the soil tray to increase the runoff rate and depth. For both soils, infiltration rate increased more than could be attributed to the increased ponding pressure head. The change in infiltration rate was particularly great for Villamblain. The measurements of hydraulic resistance showed that structural crusts had a lower hydraulic resistance than sedimentary crusts. They also showed that the crusts formed on Villamblain were of a lower hydraulic resistance than those of Blosseville. It appears that small changes in runoff depth can significantly increase infiltration rate when structural crusts of lower hydraulic resistance are inundated. The effect was less important in Blosseville which formed seals of relatively high hydraulic resistance everywhere. The results provide a suitable explanation for field observations of increasing infiltration rate with either increasing rainfall intensity or runoff rate. The results also have implications for the relationships between surface roughness, surface water storage, and infiltration.