Narrow Cylinder Research Articles

Segmental bioelectrical impedance analysis (SBIA) and blood rheology: Reducing the gap between in vivo and in vitro?

Bioelectrical impedancemetry (BIA) has been used to evaluate hematocrit and red cell aggregability in vitro but whole body impedance measurements are also correlated to some hemorheologic factors, suggesting a relationship between viscosity factors and electric properties of blood. We repeatedly reported correlations with whole body BIA and hematocrit, whole blood viscosity and plasma viscosity, red cell rigidity and RBC aggregation. The SBIA Inbody 770 modelizes body as 5 cylinders and measures impedance at 1, 5, 50, 250, 500, and 1000 kHz. With the SBIA we found that hematocrit is best correlated to leg reactance at 50 kHz but also to leg impedance at 1 and 5 kHz and trunk reactance. RBC aggregation "M" is best correlated to arm reactance at 5 kHz but also to most measurements of segmental impedance (28 correlations found). RBC aggregation "M1" is best correlated to arm reactance at 5 kHz and to 19 other impedance measurements. A predictive equation for "M" from the mean between the two arm reactances at 5 kHz (maXc5) is found: M = 2.1845maXc5-23.958 (r = 0.665, p < 0.001) that provides a satisfactory Bland-Altman plot (mean difference: 0.000524 range [-1.6;+1.6]. This study suggests that previously reported correlations between BIA and viscosity factors were not spurious, and that in a narrow cylinder such as the arm the structure of circulating blood (hematocrit, red cell aggregation) may influence the passage of an electric current by increasing reactance.

Experimental and numerical investigation of hetero-/homogeneous combustion-based HCCI of methane–air mixtures in free-piston micro-engines

The hetero-/homogenous combustion-based HCCI (homogeneous charge compression ignition) of fuel–lean methane–air mixtures over alumina-supported platinum catalysts was investigated experimentally and numerically in free-piston micro-engines without ignition sources. Single-shot experiments were carried out in the purely homogeneous and coupled hetero-/homogeneous combustion modes, involved temperature measurements, capturing the visible combustion image sequences, exhaust gas analysis, and the physicochemical characterization of catalysts. Simulations were performed with a two-dimensional transient model that includes detailed hetero-/homogeneous chemistry and transport, leakage, and free-piston motion to gain physical insight and to explore the hetero-/homogeneous combustion characteristics. The micro-engine performance concerning combustion efficiency, mass loss, energy density, and free-piston dynamics was investigated. The results reveal that both purely homogeneous and coupled hetero-/homogeneous combustion of methane–air mixtures in a narrow cylinder with a diameter of 3mm and a height of approximately 0.3mm are possible. The coupled hetero-/homogeneous mode can not only significantly improve the combustion efficiency, in-cylinder temperature and pressure, output power and energy density, but also reduce the mass loss because of its lower compression ratio and less time spent around TDC (top dead center) and during the expansion stroke, indicating that this coupled mode is a promising combustion scheme for micro-engine. Heat losses result in higher mass losses. Heterogeneous reactions cause earlier ignition, which is very favorable for the micro-device.

Axonal maintenance, glia, exosomes, and heat shock proteins.

Of all cellular specializations, the axon is especially distinctive because it is a narrow cylinder of specialized cytoplasm called axoplasm with a length that may be orders of magnitude greater than the diameter of the cell body from which it originates. Thus, the volume of axoplasm can be much greater than the cytoplasm in the cell body. This fact raises a logistical problem with regard to axonal maintenance. Many of the components of axoplasm, such as soluble proteins and cytoskeleton, are slowly transported, taking weeks to months to travel the length of axons longer than a few millimeters after being synthesized in the cell body. Furthermore, this slow rate of supply suggests that the axon itself might not have the capacity to respond fast enough to compensate for damage to transported macromolecules. Such damage is likely in view of the mechanical fragility of an axon, especially those innervating the limbs, as rapid limb motion with high impact, like running, subjects the axons in the limbs to considerable mechanical force. Some researchers have suggested that local, intra-axonal protein synthesis is the answer to this problem. However, the translational state of axonal RNAs remains controversial. We suggest that glial cells, which envelop all axons, whether myelinated or not, are the local sources of replacement and repair macromolecules for long axons. The plausibility of this hypothesis is reinforced by reviewing several decades of work on glia-axon macromolecular transfer, together with recent investigations of exosomes and other extracellular vesicles, as vehicles for the transmission of membrane and cytoplasmic components from one cell to another.

Numerical study on ring bubble dynamics in a narrow cylinder with a compliant coating

In this paper, the ring bubble contraction inside a narrow vertical rigid cylinder with a compliant coating filled with water is studied numerically. To simulate ring bubble dynamics numerically, in addition to computing the pressure and velocity fields of the surrounding fluid, an axisymmetric boundary integral equation approach is adopted alongside a finite difference method. The compliant boundary is modeled as a membrane with a spring foundation. During the ring bubble contraction and under the attraction of the cylinder wall due to the Bjerknes force, a horizontal ring jet is initiated and develops towards the cylinder wall. The numerical results represent the effects of the cylinder radius and two compliant coating characteristics, including its mass per unit area and the spring constant, on the ring bubble behavior. This investigation is motivated by the possibility of utilizing the ring jet in therapeutic cardiovascular applications.

The granularity of grasping: Comment on “Grasping synergies: A motor-control approach to the mirror neuron mechanism” by A. D'Ausilio et al.

The idea that mirror neuron systems in the human and the macaque monkey could provide a link between perceiving an action and performing it has spurred intense research [1,2]. Hundreds of papers now examine if this link exists and what it might contribute to human behaviour. The review article from D’Ausilio et al. [3] highlights how relatively few papers have considered the granularity of coding with mirror neuron systems, and even fewer have directly tested different possibilities. Granularity refers to the critical question of what actually is encoded within the mirror system – are neurons selective for low level kinematic features such as joint angle, or for postural synergies, or for action goals? Focusing on studies of single neurons in macaques and on studies measuring the excitability of primary motor cortex with TMS, the review suggests that it is very hard to distinguish low-level kinematic from goal representations. Furthermore, these two levels are often highly correlated in real-life contexts – the kinematics needed to grasp an apple are defined by the shape of the goal (an apple tends to be a large sphere) and these kinematics differ for other possible goals (a pencil which is a narrow cylinder). In some cases, kinematics may be enough to define a goal [4]. The review suggests that it is therefore arbitrary to distinguish these levels, and that a synergy level might be a better way to understand the mirror system. Synergies are a form of coding based on commonly used hand-shapes or hand postures, which take into account the fact that some joint angles are more likely to co-occur than others. Evidence that different grasp shapes are represented separately in premotor cortex has been found [5]. These could provide an intermediate level of representation between muscle activity and goals. The review proposes that a synergy level of granularity provides the best way to consider both the motor system and the role of the mirror system in understanding actions. This is a useful proposal, but has some limitations. The proposed synergies seem much closer to a kinematic representation than to goals, and do not necessarily resolve the problem of if/how the mirror neuron system could contribute to understanding goals. Just because it is not easy to separate cognitive concepts such as kinematics and goals, does not mean it should not be done. A small number of carefully designed fMRI experiments have been able to show distinct patterns of brain activity for goals and kinematics. For example, grasping a tennis ball and grasping an apple both involve the same hand kinematics and the same hand synergies, but quite different goals. Anterior intraparietal sulcus can distinguish these actions [6] and shows cross-modal sensitivity to other action goals too [7].

An experimental study of columnar crystals using monodisperse microbubbles

Abstract We investigate the ordered arrangements of monodisperse microbubbles confined within narrow cylinders. These foams were imaged using X-ray tomography, allowing the 3D positions of the bubbles of the foam to be accurately determined. The structure of these foams closely resemble the minimum energy configuration of hard spheres in cylindrical confinement as found in simulations. For larger ratios, λ, of cylinder to bubble diameter two- and three-layered crystals were formed. Each layer of these structures is found to be ordered, with each internal layer resembling structures found at lower λ values. The average number of contacts per bubble is seen to increase with λ.

Manipulating textures of rotating superfluidHe3−Aphase in a single narrow cylinder

We investigated order parameter textures of the rotating superfluid $^{3}\mathrm{He}$-A phase in a single narrow cylinder with a diameter of about 10 times the dipole coherence length by the cw-NMR method. It is theoretically proposed that in such a narrow cylinder, a few special textures will appear due to the confinement in a cylindrical geometry. We observed three types of NMR spectra in the A phase. The NMR spectra of the textures were identified by a comparison with the spin waves excited in the NMR potential using their numerically calculated resonance frequencies and relative intensities. We have established a method to selectively generate each one of the textures by controlling the conditions when the A phase was formed, such as the applied magnetic field, rotation angular velocity, and temperature.

An improved estimation of shear rate for yield stress fluids using rotating concentric cylinder Fann viscometer

Abstract This paper deals with the estimation of wall shear rates for yield stress fluids using rotating coaxial-cylinder viscometer readings. The estimation is based on the generalized difference equation for rotating narrow gap coaxial cylinder Fann Viscometer under purely steady, laminar and isothermal tangential fluid flow condition. Rotor rotations and bob deflections are the two important viscometer readings and these are used to predict wall shear rates. The proposed equations are used to calculate shear rates for several Herschel–Bulkley type fluids involving polymer (for example, xanthan gum, poly-anionic cellulose and carbomethoxy cellulose) solutions with varying concentration and bentonite suspension, which are frequently used as drilling fluid additives. Parametric sensitivity is made for stability analysis of the proposed shear rate equations. Finally, the predicted shear rates are compared with the conventional method of estimating the rate of shear for drilling fluids.

Density functional theory study of the capacitance of single file ions in a narrow cylinder

The differential capacitance of a model organic electrolyte in a cylindrical pore that is so narrow that the ions can form only a single file is studied by means of density functional theory (DFT). Kornyshev (2013), has studied this system and found the differential capacitance to have only a double hump shape (the so-called camel shape) whereas other geometries show this behavior only at low ionic concentrations that are typical for aqueous electrolytes. However, his calculation is rather approximate. In this DFT study we find that the double hump shape occurs only at low ionic concentrations. At high concentrations, the capacitance has only a single hump. Kornyshev considers a metallic cylinder and approximately includes the contributions of electrostatic images. Electrostatic images are not easily incorporated into DFT. As a result, images are not considered in this study and the question of whether Kornyshev’s result is due to his approximations or images cannot be answered. Simulations to answer this question are planned.

The Design of New Lock Keyhole and Cylinder

This essay will find a new way to prevent technical unlocking and violence through the cylinder lock through the narrow cylinder bore for the purpose of improving the performance of the theft. The miniaturization of the keyhole and cylinder locks, it makes the lock cylinder by means of the implementation does not have enough space, greatly limits the unlocking illegal activities. Meanwhile, the new lock cylinder has the advantage of mutual opening rate lower.

Design optimization of a synchronal rotary multiphase pump

Design optimization analyses of a synchronal rotary multiphase pump (SRMP) were performed to improve the pump performance. A comprehensive mathematical model of the SRMP was first developed to calculate various pump performance parameters, including the volume flow rate, shaft power consumption, and pump efficiency. The accuracy of the established model was verified by comparisons between the simulated and experimental results. A design optimization procedure coupled with the mathematical model was then developed by employing a direct search optimization technique-complex method. The optimization calculations for the optimum pump performance and the relevant design variables were implemented under three kinds of operating conditions that differed in their inlet gas volume fractions (GVFs). The calculated results showed that the pump efficiency was effectively improved by the set of optimum design variables obtained in the optimization search. The optimum design variables differed with inlet GVF. Under the condition of a lower inlet GVF, the optimum design variables inclined to values that gave a higher mechanical efficiency. When the inlet GVF increased, the effect of leakage loss on the pump efficiency increased, and as a result the optimum design variables inclined to values that gave a higher volumetric efficiency. The research results suggest that a narrow but taller cylinder is better for the operating condition of a lower inlet GVF and a wide but shorter cylinder is better for the operating condition of a higher inlet GVF.

Effects of ketamine on expression of hippocampal GABAB1 receptors and BDNF in rats with diabetic neuropathic pain complicated with depression

Objective To evaluate the effects of ketamine on the expression of gamma-aminobutyric acid type B receptor subunit 1 (GABAB1) receptors and brain-derived neurotrophic factor (BDNF) in rats with diabetic neuropathic pain (DNP) complicated with depression.Methods Pathogen-free male Sprague-Dawley rats,weighing 180-200 g,were used in the study.The model of DNP was established by intraperitoneal injection of streptozocin,and then depression was induced by forcing the rats to swim in a narrow cylinder from which they cannot escape.Forty rats with DNP complicated with depression were randomly divided into 2 groups (n =20 each) using a random number table:model control group (NS group) and ketamine group (K group).In group K,ketamine 10 mg/kg (0.5 ml) was injected intramuscularly once a day for one week.In NS group,the equal volume of normal saline was given instead of ketamine.Another 20 rats were used as normal control group (C group).Mechanical paw withdrawal threshold to von Frey stimuli (MWT) was measured and the time for immobility during forced swimming test was recorded at 1 day after completion of administration (T1) and 2nd week after completion of administration (T2).After the end of behavior test,the hippocampi of rats were removed for detection of GABAB1 receptor and BDNF expression (using immunohistochemistry and Western blot) and expression of GABAB1 receptor and BDNF mRNA (using RT-PCR).Results Compared with C group,MWT was significantly decreased,the time for immobility during forced swimming test was prolonged,and the expression of GABAB1 receptor and BDNF protein and mRNA was down-regulated in group NS.Compared with group NS,MWT was significantly increased,the time for immobility during forced swimming test was shortened,and the expression of GABAB1 receptor and BDNF protein and mRNA was up-regulated in group K.Conclusion Ketamine can upregulate the expression of GABAB1 receptor and BDNF in rats with DNP complicated with depression,thus mitigating DNP and depressed state. Key words: Ketamine; Receptors, GABA-B; Brain-derived neurotrophic factor; Diabetic neuropathies ; Depression

Stripe order in superfluid3He confined in narrow cylinders

We theoretically investigate pairing states of the spin-triplet p-wave superfluid 3He confined in narrow cylinders. The surface-induced distortion and the multiple internal degrees of freedom of the order parameter lead to the occurrence of a stripe structure along the cylinder axis in the superfluid 3He-B phase. We show that in sufficiently small cylinders with an anisotropic surface scattering, the stripe order with broken translational symmetry may be stabilized as the lowest energy state. Periodic spin-current textures caused in this inhomogeneous superfluid phase are also discussed.

Numerical investigation on the pulsating bubble dynamics in a narrow cylinder with a compliant coating

In this paper, the bubble dynamics in a narrow vertical rigid cylinder with a compliant coating filled with water is studied numerically. Considering the surface tension and the coincidence of bubble and cylinder centers, an adopted axisymmetric boundary integral equation approach besides a finite difference method is used for numerical simulation of bubble evolution accompanying with computing the pressure and velocity fields of fluid around it. The compliant boundary is modeled as a membrane with a spring foundation. It is found that the confinement of bubble by the cylinder increases greatly its lifetime and influences its behavior. The first stage of bubble contraction depicts the flattening of its top and bottom parts. A liquid counter-jet is then initiated and develops itself toward the bubble center; the bubble becomes biconcave at the end of the contraction phase. The bubble dynamics is affected by the ratio of cylinder radius to the maximum radius of the bubble. The results also represent the effects of two compliant coating characteristics including its mass per unit area and the spring constant on the bubble behavior. This investigation is motivated by the possibility of utilizing bubbles in the therapeutic cardiovascular applications.

Roles played by histamine in strenuous or prolonged masseter muscle activity in mice

Bruxism and/or clenching, resulting in fatigue or dysfunction of masseter muscles (MM), may cause temporomandibular disorders. Functional support of the microcirculation is critical for prolonged muscle activity. Histamine is a regulator of the microcirculation and is supplied by release from its stores and/or by de novo production via the induction of histidine decarboxylase (HDC). Interleukin (IL)-1, a cytokine involved in temporomandibular disorders, is an inducer of HDC. In the present study, we examined the roles of histamine, HDC and IL-1 in MM activity. Experiments were conducted using our R+G+ model. A mouse restrained (R+) inside a narrow cylinder (front end blocked with a thin plastic strip) gnaws away (G+) the strip to escape, with the weight reduction in the strip serving as an index of MM activity. Fexofenadine (a peripherally acting histamine H1 receptor antagonist) reduced MM activity in normal mice. Both H1 receptor-deficient and HDC-deficient mice exhibited low MM activity. Prolonged R+G+ induced HDC activity in MM. Mast cell-deficient mice exhibited strikingly low HDC induction in MM (and also in the quadriceps femoris muscle) in response to muscle activity or IL-1β. Mast cells were present around blood vessels and nerves in the epimysium and perimysium of MM. These results, together with others reported previously, suggest that: (i) peripheral histamine supports strenuous MM activity; (ii) strenuous MM activity stimulates mast cells to release histamine and to induce HDC (which replenishes the histamine pool in mast cells, possibly mediated by IL-1); and (iii) peripheral histamine H1 receptor antagonists may be effective in treating temporomandibular disorders or preventing prolonged clenching and/or bruxism.

An improved shear rate estimation using rotating coaxial cylinder Fann viscometer

Abstract In this study, an improved formula for shear rate calculation has been proposed for drilling fluids, and is estimated using the generalized difference equation for the rotating narrow gap coaxial cylinder Fann Viscometer under purely steady, laminar and isothermal tangential fluid flow condition. Rotor rotating speeds and bob dial readings are the important input variables for shear rate prediction. The proposed equation was used to calculate shear rates accurately for several non-Newtonian fluids, mainly, synthetic crude oil, aqueous bentonite suspension, aqueous hydroxypolyacrylamide solution and aqueous xanthan gum polymer solution. Finally, the predicted consistency plots were compared with those which are obtained from the conventional method of estimating the rate of shear for drilling fluids.

Milestoning with coarse memory

Milestoning is a method used to calculate the kinetics of molecular processes occurring on timescales inaccessible to traditional molecular dynamics (MD) simulations. In the method, the phase space of the system is partitioned by milestones (hypersurfaces), trajectories are initialized on each milestone, and short MD simulations are performed to calculate transitions between neighboring milestones. Long trajectories of the system are then reconstructed with a semi-Markov process from the observed statistics of transition. The procedure is typically justified by the assumption that trajectories lose memory between crossing successive milestones. Here we present Milestoning with Coarse Memory (MCM), a generalization of Milestoning that relaxes the memory loss assumption of conventional Milestoning. In the method, milestones are defined and sample transitions are calculated in the standard Milestoning way. Then, after it is clear where trajectories sample milestones, the milestones are broken up into distinct neighborhoods (clusters), and each sample transition is associated with two clusters: the cluster containing the coordinates the trajectory was initialized in, and the cluster (on the terminal milestone) containing trajectory's final coordinates. Long trajectories of the system are then reconstructed with a semi-Markov process in an extended state space built from milestone and cluster indices. To test the method, we apply it to a process that is particularly ill suited for Milestoning: the dynamics of a polymer confined to a narrow cylinder. We show that Milestoning calculations of both the mean first passage time and the mean transit time of reversal-which occurs when the end-to-end vector reverses direction-are significantly improved when MCM is applied. Finally, we note the overhead of performing MCM on top of conventional Milestoning is negligible.

Radial distribution and axial dispersion of suspended particles inside a narrow cylinder due to mildly inertial flow

The combined effects of radial drift due to flow inertia and diffusion due to Brownian motion significantly modify the radial probability distribution and the axial dispersion of conduit-bound suspended bodies. This interplay depends on the product of Peclet Pe and Reynolds Re numbers so that even apparently non-Brownian systems with high Pe exhibit the changes if Re is small. This article describes the probability distribution and the Taylor dispersion coefficient under such conditions for systems with low vessel-to-particle size-ratios where the effect is especially pronounced, but the flow-simulation is considerably difficult. We also identify the parametric regimes and the physical conditions required to see a substantial manifestation of the effect.

The important role of reactions between atoms and radicals in flame propagation in cylinder reactors

Results from studying features of the combustion of hydrogen in narrow cylinder reactors with diameters of <5.0 cm are presented. It is determined that the lower concentration limit of flame propagation in a reactor with a diameter of 1.1 cm is higher than 9% H2. The dependence of the principles of combustion on the method of initiation is studied. Mathematical simulations are performed that prove the impossibility of describing the combustion of hydrogen-deficient mixtures without assuming the cell structure of a flame. It is experimentally determined that increasing the termination of chains during the propagation of a flame results in its attenuation. It is noted that in addition to conductive heat abstraction, the recombination of atoms and radicals on the surface of the reactor plays an important role. It is concluded that these heterogeneous reactions representing the termination of reaction chains also result in the removal of recombination energy by the reactor’s walls.

Textures of Rotating Superfluid 3He–A in a Single Narrow Cylinder

We have studied textures of the rotating superfluid 3He–A in a single narrow cylinder by NMR measurement. In a narrow cylinder, the characteristic textures such as Mermin-Ho texture (Mermin and Ho in Phys. Rev. Lett. 36:594, 1976) can be formed in order to minimize the free energy of the system determined by the effect of the wall, the magnetic field, the dipole interaction, the flow of the superfluid and so on. We observed three types of NMR absorption spectra dependent on the processes used to form A-phase in a narrow cylinder. A particular texture shows a characteristic spectrum and we can determine the texture from the observed spectrum by comparing the resonance frequency of the peak in NMR spectrum with the calculated one of the spin wave mode. We present the identification and the phase diagram of textures of the rotating superfluid 3He–A in a single narrow cylinder.