Continuous Tumbling Research Articles

Unsteady electrorotation of a viscous drop in a uniform electric field

A dielectric drop suspended in an immiscible dielectric fluid of higher conductivity can spontaneously generate the so-called Quincke rotation (a rotating activity that a weakly conducting drop/solid particle displays in an electric field) subjected to sufficiently strong electric field strength. The steady tilt has been extensively studied and is well elucidated now. However, the unsteady electrorotation of drop remains a largely unclear, complex issue. Motivated by this, we examine the unsteady drop electrorotation in this work with the required integrated convective bulk charge transport effect. First, for the steady rotation, the transient evolution to a steady droplet tilt from the symmetric Taylor state is analyzed in-depth. Here we discover several new phenomena, including the evolving equatorial charge jets. For unsteady rotation, based on a drop's interfacial charge variation, deformation, and tilt angle, the study reports the growth of three distinct rotating patterns in the viscosity ratio range 0.2≤λ=μi/μo≤20.0 and electric field strength E0≤25 kv/cm at a fixed conductivity ratio Q ( = σi/σo) = 0.026 and permittivity ratio S (= ϵi/ϵo) = 0.566. A low-viscosity drop ( λ≤2.5) exhibits only the periodic rotation. For the viscosity ratio 2.5<λ<7.0, the increased electric intensity creates two new unsteady rotation modes: the pseudo-periodic tumbling and the irregular one. For λ≥7, the periodic mode remains absent; instead, the drop displays the electric intensity-dependent tumbling and irregular rotation patterns. Our study shows that the rotation reduces a drop's transitory interfacial charge. At this stage, the drop rotation behavior is controlled by competing charge convection due to fluid flow and charge supply by conduction. The resulting varying electric Reynolds number ReE (the time ratio of charge relaxation and charge convection) explains the created different rotation mechanisms. For ReE>1, owing to lacking enough interfacial charge to sustain rotation, the drop's transition to a temporary non-rotating Taylor state occurs until the interface recharges. The resultant mechanism supports the periodic batch-type rotation for a low-viscosity drop and the irregular rotation for a high-viscosity drop in a higher electric field. In contrast, for ReE<1, the drop timely acquires sufficient charge to support continuous tumbling electrorotation.

Thermally fluctuating, semiflexible sheets in simple shear flow.

We perform Brownian dynamics simulations of semiflexible colloidal sheets with hydrodynamic interactions and thermal fluctuations in shear flow. As a function of the ratio of bending rigidity to shear energy (a dimensionless quantity we denote S) and the ratio of bending rigidity to thermal energy, we observe a dynamical transition from stochastic flipping to crumpling and continuous tumbling. This dynamical transition is broadened by thermal fluctuations, and the value of S at which it occurs is consistent with the onset of chaotic dynamics found for athermal sheets. The effects of different dynamical conformations on rheological properties such as viscosity and normal stress differences are also quantified. Namely, the viscosity in a dilute dispersion of sheets is found to decrease with increasing shear rate (shear-thinning) up until the dynamical crumpling transition, at which point it increases again (shear-thickening), and non-zero first normal stress differences are found that exhibit a local maximum with respect to temperature at large S (small shear rate). These results shed light on the dynamical behavior of fluctuating 2D materials dispersed in fluids and should greatly inform the design of associated solution processing methods.

Feasibility study of Ulva sp. (Chlorophyta) intensive cultivation in a coastal area of the Eastern Mediterranean Sea

AbstractIncreasing biomass production yields is a critical challenge for macroalgae biorefineries. The continuous tumbling and mixing of free‐floating algae through water or airflow has been shown to increase the productivity of algae in land‐based cultivation systems. This approach has not been tested thoroughly in offshore cultivation. We report, here, a field feasibility study on the increase in green macroalga Ulva sp. growth rates in offshore cages, achieved by the combined effect of tumbling and mixing of the algae using influxes of water and air. The experimental system was tested in a shallow coastal area in central Israel, in the eastern Mediterranean Sea. A maximum daily growth rate of 19.2%, areal productivity of 33.72 g dry weight (DW) day−1 m−2, and volumetric yields of 37.78 g DW day−1 m−3, together with 38.47 ± 0.01% ash and 5.28% protein content on a dry matter basis were achieved in the cages with intensified cultivation in the first week of May 2017. Our study shows that cultivation with tumbling and mixing of biomass with air, and water exchange with the environment is a feasible method to increase Ulva sp. biomass productivity offshore. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd

Effect of different tumbling marination methods and time on the quality characteristics of prepared pork chops

The combined effects of tumbling marination methods (Vacuum continuous tumbling marination, CT; Vacuum intermittent tumbling marination, IT) and effective tumbling time (4, 6, 8 and 10 h) on quality characteristics of prepared boneless pork chops were investigated. The results showed that regardless of tumbling time, CT method significantly increased the pH, product yield, cohesiveness, resilience, sensory tenderness and overall flavor (p<0.05) compared with IT method, and CT method also significantly decreased the pressing loss, cooking loss, shear force value (SFV), hardness and chewiness (p<0.05) compared with IT method. With the effective tumbling time increasing from 4 h to 10 h, the product yield and sensory attributes of prepared pork chops increased at first and then decreased, whereas the pressing loss, cooking loss, SFV, hardness and chewiness decreased at first and then increased. Additionally, an interaction between CT method and effective tumbling time was also observed. These results suggested that CT method of 8 h obtained the best quality characteristics of prepared pork chops, which should be adopted.

Effect of Different Tumbling Marination Methods and Time on the Water Status and Protein Properties of Prepared Pork Chops.

The combined effect of tumbling marination methods (vacuum continuous tumbling marination, CT; vacuum intermittent tumbling marination, IT) and effective tumbling time (4, 6, 8, and 10 h) on the water status and protein properties of prepared pork chops was investigated. Results showed that regardless of tumbling time, CT method significantly decreased the muscle fiber diameter (MD) and significantly increased the total moisture content, product yield, salt soluble proteins (SSP) solubility, immobilized water component (p<0.05) compared with IT method. With the effective tumbling time increased from 4 h to 10 h, the fat content and the MD were significantly decreased (p<0.05), whereas the SSP solubility of prepared pork chops increased firstly and then decreased. Besides, an interactive effect between CT method and effective tumbling time was also observed for the chemical composition and proportion of immobilized water (p<0.05). These results demonstrated that CT method of 8 h was the most beneficial for improving the muscle structure and water distribution status, increasing the water-binding capacity and accelerating the marinade efficiency of pork chops; and thus, it should be chosen as the most optimal treatment method for the processing production of prepared pork chops.

Effect of different tumbling marination treatments on the quality characteristics of prepared pork chops.

The effect of different tumbling marination treatments (control group, CG; conventional static marination, SM; vacuum continuous tumbling marination, CT; vacuum intermittent tumbling marination, IT) on the quality characteristics of prepared pork chops was investigated under simulated commercial conditions. The CT treatment increased (p<0.05) the pH value, b* value, product yield, tenderness, overall flavor, sensory juiciness and overall acceptability in comparison to other treatments for prepared boneless pork chops. The CT treatment decreased (p<0.05) cooking loss, shear force value, hardness, gumminess and chewiness compared with other treatments. In addition, CT treatment effectively improved springiness and sensory color more than other treatments. However, IT treatment achieved the numerically highest (p<0.05) L* and a* values. These results suggested that CT treatment obtained the best quality characteristics of prepared pork chops and should be adopted as the optimal commercial processing method for this prepared boneless pork chops.

Effect of different tumbling marinade treatments on the water status and protein properties of prepared pork chops.

Recently, in consideration of the rapidly increasing demand for meat products and the trend towards fast food consumption, the prepared boneless pork chop, as a new style of value-added product, is cut from pork loins and welcomed by consumers after marinating or further cooking. The effect of different tumbling marinade treatments (control group, CG; conventional static marinade, SM; vacuum continuous tumbling marinade, CT; vacuum intermittent tumbling marinade, IT) on the water status and protein properties of prepared pork chops was investigated. The CT treatment significantly increased T22 peak area ratio compared with other treatments (P < 0.05). Histological microstructure results showed that CT treatment significantly increased solubility of salt-soluble proteins and decreased muscle fiber diameter compared with other treatments (P < 0.05). The net enthalpy (ΔH) of IT treatment was significantly lower than SM treatment (P < 0.05), whereas the protein denaturation temperature (Tm3 ) and ΔH3 of CT treatment were lower than IT treatment. These results suggest that CT treatment was more effective in improving the water mobility and distribution, promoting the denaturation of muscle protein and accelerating the marinade efficiency of pork chops compared with other treatments. Thus CT treatment should be adopted.

Pressure-Driven DNA in Nanogroove Arrays: Complex Dynamics Leads to Length- and Topology-Dependent Separation

The motion of linear and circular DNA molecules is studied under pressure driven buffer flow in a 50 nm slit channel with arrays of transverse 150 nm deep nanogrooves. Transport occurs through two states of propagation unique to this nanogroove geometry, a slow, stepwise groove-to-groove translation called the "sidewinder" and a fast, continuous tumbling across the grooves called the "tumbleweed". Dynamical transitions between the two states are observed at fixed buffer velocity. Molecules exhibit size- and topology-dependent velocities.

Tumbling approach towards template-free synthesis of EMT zeolite

Abstract The zeolite EMT has been synthesized with 18-crown-6/Al 2 O 3 ratios as low as 0.14, by applying continuous tumbling of the synthesis mixture during the entire aging and crystallization period. The crystalline product contained only two crown ether molecules per unit cell, and the mother liquor was essentially free of crown ether. It was found that the lower the amount of crown ether, the slower the rate of crystallization and the smaller the crystallites of the product, whereas the total product yield remained well above 90% based on aluminum. With lower crown ether content the range of synthesis conditions under which EMT was obtained became increasingly narrower, presumably because of the increasing probability of nucleating of other phases such as cubic faujasite when less 18-crown-6 is present.

連続式転動流動層コーティング装置における粒子の成長

連続式転動流動層コーティング装置における粒子の成長

Fundamental kinetic study of aluminization of iron by pack cementation at 900 °C

The kinetics of pack aluminization of iron at 900 °C, using NaCl as the activator under both argon and forming gas (5% H 2 + Ar) atmospheres, has been studied. The coating system was simplified by using a low aluminum activity masteralloy of 42wt.%Al–58wt.%Fe to avoid the formation of intermetallic compounds at the substrate surface. The chemically depleted zone in the pack was eliminated by a continuous tumbling of the system during coating. The substrate was wrapped with a ceramic sheath to allow a particle-free surface and to introduce a diffusion barrier for the transporting gaseous species. The rate-limiting step for the aluminizing process was shown to be series transport of the gaseous species from the pack to the substrate surface and solid state diffusion in the substrate. A kinetic model is proposed and compared with the experimentally obtained data, and results are in good agreement.

連続式転動流動層コーティング装置の開発とその装置特性

A continuous tumbling fluidized bed coater was newly developed. The apparatus has an inlet pipe and several overflow pipes on the side wall of the coating chamber, unlike that of a batch system. The basic characteristics of the apparatus, such as the residence time distribution of seed particles and the relationship between mean residence time and operating factors were investigated. It was found that seed particles were mixed perfectly in spite of their maldistribution in the coating chamber. Also the mean residence time varied inversely with the feed rate of the particles and the flow rate of the inlet air, and it increased with the height of the overflow pipe. However, the phenomena was complicated for the disk rotation speed. The mean residence time decreased with the disk rotation speed below a certain value but increased with it above that value. Continuous coating experiments were also tried and were succesful. The relationship between the coating efficiency and the operating conditions in continuous operation seemed to be essentially the same as that in batch operation.

Mars ultraviolet simulation facility.

A facility was established for long-duration ultraviolet (UV) radiation exposure of natural and synthetic materials in order to test hypotheses concerning Martian soil chemistry observed by the Viking Mars landers. The system utilized a 2500 watt xenon lamp as the radiation source, with the beam passing through a heat-dissipating water filter before impinging upon an exposure chamber containing the samples to be irradiated. The chamber was designed to allow for continuous tumbling of the samples, maintenance of temperatures below 0 degrees C during exposure, and monitoring of beam intensity. The facility also provided for sample preparation under a variety of atmospheric conditions, in addition to the Mars nominal. As many as 33 sealed sample ampules have been irradiated in a single exposure. Over 100 samples have been irradiated for approximately 100 to 700 h. The facility has performed well in providing continuous UV irradiation of multiple samples for long periods of time under simulated Mars atmospheric and thermal conditions.

Influence of Continuous Versus Intermittent Tumbling on Brine (Salt, Sugar and Nitrite) Diffusion in Porcine Tissue

Increased tumbling time and intermittent tumbling (10 min per hour for 18 h of tumbling) when compared (on a tumbling time basis) to continuous tumbling (3 h), both increase migration of individual cure components (sodium chloride, dextrose, sodium nitrite) as well as average brine (average migration of these components) in tumbled porcine muscle. In most instances the difference between intermittent and continuous tumbling became apparent at 1-1/2 to 2 h of tumbling time and remained significantly higher for the intermittent tumbling technique for the remainder of the 3-h tumbling treatment. Tumbling time for both continuous and intermittent tumbling increased cure migration but these results indicate that continuous tumbling did not have the same influence on cure ingredient migration as equivalent tumbling time delivered intermittently.

EFFECT OF TUMBLING METHOD, PHOSPHATE LEVEL AND FINAL COOK TEMPERATURE ON HISTOLOGICAL CHARACTERISTICS OF TUMBLED PORCINE MUSCLE TISSUE

ABSTRACTSix groups of hams were cured, tumbled, canned and cooked. Duplicate histological samples were removed from both the surface and deep muscles of fresh, cured and cooked hams, prepared and stained both with haematoxylin and trichrome staining solutions. Results indicated that tumbling significantly (P &lt; 0.01) increased cell membrane disruption, and phosphate level had a significant (P &lt; 0.01) quadratic effect on decreasing clarity of striation patterns. On a tumbling time constant basis, intermittent tumbling resulted in more alterations in cell structure than did continuous tumbling. Tumbling also had a significant (P &lt; 0.01) effect on disorganizing nuclei as well as a significant (P &lt; 0.05) effect on decreasing clarity of striation patterns of deep muscle samples.

INFLUENCE OF TUMBLING, TUMBLING TIME, TRIM AND SODIUM TRIPOLYPHOSPHATE ON QUALITY AND YIELD OF CURED HAMS

ABSTRACTForty‐four boneless, cured hams were assigned to treatment groups to study the effect of tumbling, tumbling time (18 hr intermittent, 9.5 hr intermittent, 3 hr continuous), tumbling temperature (5°C and 15°C), sodium tripolyphosphate (TPP) pickle level (0 and 3.3%), and trim (lean, regular, and fat) on the quality and yield of canned hams. Tumbling significantly improved ham external appearance, color, slicability, taste and aroma, and yield. Three‐hour continuous tumbling resulted in less improvement in product quality and yield than did the 18‐hr intermittent tumbling. Significant improvements in external appearance, color, sliceability, taste and aroma, and yield resulted from TPP treatments. Hams trimmed to 3 mm fat cover or less before tumbling had significantly better sliceability and yield.

Intrinsic and extrinsic light responses of Salmonella typhimurium and Escherichia coli.

Exposure to intense light in the region between 390 and 530 nm has been shown to have three effects on the motility of Salmonella typhimurium and Escherichia coli. Short pulses of light initiate continuous tumbling. Longer exposures to light induce smooth swimming, and prolonged exposures induced paralysis. The tumbling response is intimately connected with the chemical gradient-sensing apparatus of the bacterium and can be overcome by strong temporal gradients of attractant. Some mutants of S. typhimurium which are defective in the tumble-generating mechanism for chemotaxis are also unable to tumble in intense light. This intrinsic light effect can be mimicked by the addition of external dyes (the classical photodynamic effect), but it can be shown that the two phenomena are distinct. The extrinsic (photodynamic) effect can be inhibited by histidine or by anaerobic conditions, whereas the intrinsic effect is not. The observation that the extrinsic effect can also produce the three types of light responses listed above suggests a common pathway after an intial event on either an endogenous or an externally added photoreceptor.

On the Aerodynamics of Spheroidal Hailstone Models

Abstract Drag, lift and torques for smooth oblate spheroids, of axis ratio from 0.50 to 0.79, were measured over a range of Reynolds number from 4×104 to 4×105 at various inclination angles of the models to the flow. The data show that the aerodynamic forces and moments do not vary greatly up to the range of the critical Reynolds numbers where the drag decreases, and the lift and torque increase. Assuming that the values measured at steady-state conditions are adequate for calculations, the behavior of freely-failing hailstones was numerically modelled. Data about horizontal motions and periodic variations of rotational and vertical speeds are given in addition to average vertical speeds and oscillating or tumbling motions. The effect of a possible but unknown damping was also considered. Thereby, it could he shown that given a small perturbation from the steady state with the minor axis vertical, either amplification will lead to constant-amplitude oscillation or continuous tumbling, or damping will rest...

Influence of Dynamic Calcination on Crystallite Growth of Submicron Rare‐Earth Oxides

The crystallite growth of rare‐earth oxide powders with particle sizes of 10 to 30 Å obtained by the hydrolytic decomposition of alkoxides was investigated. These powders were compared with commercially available powders with average particle sizes from 1000 Å to 10 μm. Static and dynamic atmosphere tests were made, the latter by continuous tumbling during calcination. Dynamic calcination controlled crystallite growth effectively while maintaining uniform particle size. Typical arithmetic mean particle sizes were 250 Å for powders calcined at 800°C for 24 h with tumbling and ∼400 Å for powders calcined under identical conditions without tumbling. TGA, X‐ray diffraction, and emission spectrographic analyses were used to characterize the powders. Electron microscopy and BET surface area measurements demonstrated the importance of the dynamic calcination method in the growth of primary crystallites into larger particles during the presintering stage of the processing of these powders.