Sinusoidal Cavities Research Articles

From Marrow to Bone and Fat: Exploring the Multifaceted Roles of Leptin Receptor Positive Bone Marrow Mesenchymal Stromal Cells.

The bone marrow (BM) stromal cell microenvironment contains non-hematopoietic stromal cells called mesenchymal stromal cells (MSCs). MSCs are plastic adherent, form CFU-Fs, and give rise to osteogenic, adipogenic, chondrogenic progenitors, and most importantly provide HSC niche factor chemokine C-X-C motif ligand 12 (CXCL12) and stem cell factor (SCF). Different authors have defined different markers for mouse MSC identification like PDGFR+Sca-1+ subsets, Nestin+, or LepR+ cells. Of these, the LepR+ cells are the major source of SCF and CXCL12 in the BM microenvironment and play a major role in HSC maintenance and hematopoiesis. LepR+ cells give rise to most of the bones and BM adipocytes, further regulating the microenvironment. In adult BM, LepR+ cells are quiescent but after fracture or irradiation, they proliferate and differentiate into mesenchymal lineage osteogenic, adipogenic and/or chondrogenic cells. They also play a crucial role in the steady-state hematopoiesis process, as well as hematopoietic regeneration and the homing of hematopoietic stem cells (HSCs) after myeloablative injury and/or HSC transplantation. They line the sinusoidal cavities, maintain the trabeculae formation, and provide the space for HSC homing and retention. However, the LepR+ cell subset is heterogeneous; some subsets have higher adipogenic potential, while others express osteollineage-biased genes. Different transcription factors like Early B cell factor 3 (EBF3) or RunX2 help maintain this balance between the self-renewing and committed states, whether osteogenic or adipogenic. The study of LepR+ MSCs holds immense promise for advancing our understanding of HSC biology, tissue regeneration, metabolic disorders, and immune responses. In this review, we will discuss the origin of the BM resident LepR+ cells, different subtypes, and the role of LepR+ cells in maintaining hematopoiesis, osteogenesis, and BM adipogenesis following their multifaceted impact.

Natural Convection of Nanofluids in Partially Filled Metal Foam Sinusoidal Cavities

Natural Convection of Nanofluids in Partially Filled Metal Foam Sinusoidal Cavities

Natural convection heat transfer characteristics of sinusoidal cavities filled with nanofluids

To improve the heat transfer of free convection of cavity in the field of photothermal conversion and cooling of electronic components, new sinusoidal cavities were developed. The heat transfer properties of Fe3O4-H2O nanofluids in the novel cavities were studied experimentally. The influence of three amplitudes (A=1 mm, A=2 mm, A=3 mm) and three wave numbers (n = 1, n = 2, n = 3), four mass fractions (wt%=0.0%, wt%=0.1%, wt%=0.3%, wt%=0.5%) and four heating powers (Q=10 W, Q=15 W, Q=20 W, Q=25 W) on heat transfer behavior was researched. The results showed that when the amplitude is A= 3 mm and the wave number is n = 2, the Nusselt number is the largest, and the heat exchange cavity exhibits the best heat transfer performance, the Nusselt number increases with nanofluids mass fraction and heating power. It provides important guidance for the design of cavities in the field of photothermal conversion and cooling of electronic components.

Modifications in the physical structure of a new two-layer micro-size heat sink with sinusoidal shaped cavities for heat transfer augmentation of nanofluid flow

This paper presents numerical simulation of graphe nanoplatelet (GNP) – sodium dodecylbenzene sulfonate (SDBS) – water nanofluid with volumetric mass fractions of ϕ equal to 0–0.1%. The new microchannel is made of 2 layers and has sinusoidal cavities along with the heat sink. The study was conducted for Re = 50, 300, 700 and 1000 (laminar flow). Based on the results, higher Re leads to more convective heat transfer coefficient. Therefore, the value of temperature gradients decreases and on the other hand the effect of cooling fluid temperature in warm areas near solid wall becomes important. Using a higher value of Re results in the penetration of heat in the fluid layer decreases which in general will reduce the temperature of the outlet section in larger Re values. Also, larger Re value results in larger development length which is also a cause for lack of thermal development and dominance of the temperature of the coolant flow in the heat sink resulting in decreased outlet section temperature for higher Reynolds numbers. For Re = 50 and 300 because of lower fluid velocity, the effect of surface geometry factors such as sinusoidal paths or hollow parts (cavities) has a smaller influence on the pressure loss or friction factor of the flow.

Thermohydraulic assessment of a novel hybrid nanofluid containing cobalt oxide-decorated reduced graphene oxide nanocomposite in a microchannel heat sink with sinusoidal cavities and rectangular ribs

The goal of this article is to assess the merit of utilizing an innovative water-based nanofluid containing the reduced graphene oxide‑cobalt oxide hybrid nanocomposite in a microchannel heat sink equipped with rectangular ribs and sinusoidal cavities. For this end, the two-phase mixture numerical model based on the finite volume technique and Coupled approach is used. The simulation is conducted at amounts of Reynolds number ranged from 100 to 500 with the nanofluid concentrations of 0.05%, 0.1%, and 0.2%. The thermophysical properties are temperature-dependent. The results indicate that though the created vortices decline by utilizing the nanofluid, the thermal features significantly improve due to enhanced thermal conductivity. The convective heat transfer coefficient, solid temperature, temperature uniformity, and thermal resistance promote by maximum amounts of 14%, 2.3%, 27%, and 25%, respectively. Also, considering the imposed pressure drop due to the use of the nanofluid, it was found that in all the cases, the nanofluid increases the heat transfer coefficient more than the pressure drop, which is an excellent outcome. Finally, it is unmasked that deploying the 0.2% nanofluid at Reynolds number of 500 improves the thermal features with the least pressure drop increment, and therefore, this case is recommended for practical applications.

Cardiac resynchronization therapy in a patient with left ventricular non-compaction cardiomyopathy: A case report

Introduction: Left ventricular non-compaction cardiomyopathy (LVNC) is a rare and specific type of congenital cardiomyopathy with an incidence rate between 0.05% and 0.24%. Dilated cardiomyopathy (DCM) and ischemic cardiomyopathy have poor prognosis. Cardiac resynchronization therapy (CRT) improves cardiac function and long-term prognosis in patients with heart failure with left bundle branch block, but its efficacy on LVNC is uncertain. Case Report: This paper reported a case of a 57-year-old male with LVNC who was hospitalized for complaining of palpitations and shortness of breath on exertion and then diagnosed as heart failure. Electrocardiogram revealed a sinus rhythm with a QRS duration of 164 ms, as well as left bundle branch block morphology. Chest X-ray showed marked cardiomegaly and mild pulmonary congestion, and ultrasound echocardiography showed abnormal echo of left ventricular myocardium. The myocardium was cavernous sinus-like, forming sinusoidal cavities in varying sizes, communicating with left ventricular cavity, with the ratio of non-compacted to compacted myocardium of 3:1. The patient featured a large left ventricular end-diastolic diameter of 91 mm, and the function was severely impaired with an ejection fraction (EF) of 31%. After diuretic treatment, improvement of myocardial remodeling, heart strengthening, vasodilation, etc., he recovered gradually and was discharged 20 days later. However, the patient was admitted to hospital again due to shortness of breath within one month without obvious inducement. Considering the poor effect of drug therapy, we recommended that the patient undergo cardiac resynchronization therapy, he recovered and was discharged seven days after surgery. During the 6-month follow-up period, his left ventricle (LV) function and clinical symptoms showed significant and sustained improvement. B-type natriuretic peptide (BNP) levels decreased from 4836.79 to 1253.18 pg/mL. QRS duration (164 ms) on ECG significantly decreased after CRT. Conclusion: We reported the management of a rare case of congenital LVNC with recurrent heart failure and frequent premature ventricular contractions. Patients with LVNC have clear indications and poor pharmacological response. Early cardiac resynchronization treatment might benefit them.

Thermal Performance Analysis in Sinusoidal-Cavities-Ribs Microchannel Heat Sink with Secondary Channel Geometry for Low Pumping Power Application

The increases in the demand for high performance electronic device has led cooling technology from air cooling to liquid cooling method in order to prevent the operating temperature in the electronic device goes beyond the junction temperature of the electronic device. Liquid as a heat transportation in a micro-cooling technology is an effective method to maintain the operating temperature. Among the micro-cooling technology, microchannel heat sink appears as a promising method that provides high heat transfer rate with minimal pressure drop. However, the conventional microchannel heat sink which has straight channels (CR MCHS) inadequate to remove high heat flux generated by the current devices due to high thermal resistance in laminar region. High heat transfer rate just can be obtained in the microchannel heat sink by using a large mass flowrate which affects the pumping power consumption. The method is not suitable for the low pumping power application. So instead of increases the mass flowrate, in this paper, a hybrid microchannel heat sink was proposed in order to satisfy the cooling demand with low pumping power consumption. The effect of sinusoidal cavities, rectangular ribs and secondary channel geometry on thermal resistance and pumping power in the hybrid microchannel sink (SD-RR-SC MCHS) was studied numerically. The result showed the SD-RR-SC MCHS and RR MCHS had the lowest thermal resistance and temperature variation for the mass flowrate that less than 6.78×10−5 kg/s. Despite both designs had a similar thermal performance with the average deviation of 5%, SD-RR-SC MCHS required only 11.3% of CR MCHS pumping power, while RR MCHS required 31.3% of CR MCHS pumping power in order to achieve the optimum thermal performance of CR MCHS. Means, SD-RR-SC MCHS is the most suitable design which can fulfil cooling demand for low pumping power application.

Numerical investigation of thermal performance augmentation of nanofluid flow in microchannel heat sinks by using of novel nozzle structure: sinusoidal cavities and rectangular ribs

In this paper, we present a numerical simulation of a laminar, steady and Newtonian flow of f-graphene nanoplatelet/water nanofluid in a new microchannel design with factors for increasing heat transfer such as presence of ribs, curves to enable satisfactory fluid mixing and changing fluid course at the inlet and exit sections. The results of this study show that Nusselt number is dependent on nanoparticles concentration, inlet geometry and Reynolds number. As the nanofluid concentration increases from 0 to 0.1% and Reynolds number from 50 to 1000, the Nusselt number enhances nearly up to 3% for increase in fluid concentration and averagely from 15.45 to 54.1 and from 14.5 to 55.9 for geometry with and without rectangular rib, respectively. The presence of ribs in the middle section of microchannel and curves close to hot walls causes a complete mixing of the fluid in different zones. When the nanoparticles concentration is increased, the pressure drop and velocity gradient will become higher. An increased concentration of nanoparticles in contribution with higher Reynolds numbers only increases the fraction factor slightly. (The fraction factor increases nearly 37% and 35% for Re = 50 and 1000, respectively.) The highest uniform temperature distribution can be found in the first zones of fluid in the microchannel and by further movement of fluid toward exit section, because of decreasing difference between surface and fluid temperature, the growth of temperature boundary layer increases and results in non-uniformity in temperature distribution in microchannel and cooling fluid. With decrease in the concentration from 0 to 0.1%, the average outlet temperature and FOM decrease nearby 0.62% and 6.15, respectively.

Heat transfer enhancement of ferrofluid flow within a wavy channel by applying a non-uniform magnetic field

This paper presents the effects of a non-uniform magnetic field on the hydrodynamic and thermal behavior of ferrofluid flow in a wavy channel by 3D numerical simulation. The wavy surfaces at the top and bottom of the channel are heated by constant heat fluxes. Moreover, the sidewalls are adiabatic. In the wavy section, in the perpendicular direction of the main flow, the magnetic field that linearly varies along the direction of the main flow is applied. The mathematical model that is consistent with the principles of ferrohydrodynamics and magnetohydrodynamics is used for the problem formulation. The results indicate that the wavy wall enhances the heat transfer rate on the bottom of the channel in comparison with the plain wall, while it does not have any significant effect on the top wall where the natural convection is weak. Furthermore, it can be found that the influence of the magnetic field on the flow field and heat transfer in the channel with the wavy walls is greater than one for the channel with the plain walls. This is due to the elimination of the recirculation zones in the sinusoidal cavities of the wavy walls by applying the magnetic field. The rise of the magnetic gradient value from 0 to 1.5 × 105 increases the skin-friction factors on the top and bottom wavy walls by factors of 11 and 1.6, respectively. In addition, it changes the Nusselt number 40% and 300% for the bottom and top walls, respectively.

Numerical investigation of heat transfer of nanofluid flow through a microchannel with heat sinks and sinusoidal cavities by using novel nozzle structure

In this study, we analyze laminar flow for f-GNP nanofluid flow in different concentrations of solid nanoparticles. The computational domain of flow field and heat transfer is 3D, and for Re = 50, 100, 300, 700, a new rectangular microchannel design with cavity will be analyzed. The main objective of this study is determining the effect of boundary condition of inlet velocity for two structures in rectangular microchannel. Other goals of this study are investigating the effect of concentration of solid nanoparticles and Reynolds number on parameters including Nusselt number, friction factor and pressure drop and heat fluid performance evaluation criterion in different fluid and geometric parameters. The results of this study show that changing the direction of fluid at inlet and exit section has an important effect on flow field and heat transfer. Also, by adding a component to fluid velocity at inlet and exit sections, the value of heat transfer and friction factor will be increased. Using microchannel design with dimple can also create a good mixing for fluid during motion. Due to the solid walls, the momentum depreciation is greater in case (1), and also this affects the core regions of the fluid flow. In the microchannel, because of changes in the velocity components in different directions during the entrance of flow in microchannel, the mixing of the fluid for different regions and the amount of heat absorption increase. The existence of cavities in the flow path causes secondary flow to increase the temperature of the fluid during movement. In the microchannel case (2), due to direct fluid movement path, the velocity gradients are reduced and this prevents better mixing of the fluid and the heat transfer. Therefore, the distribution of temperature between the fluids is reduced and the layers of fluid close to the microchannel floor will experience higher temperature in comparison with other regions.

Thermal performance improvement in water nanofluid/GNP–SDBS in novel design of double-layer microchannel heat sink with sinusoidal cavities and rectangular ribs

In this numerical study, laminar flow of water nanofluid/GNP–SDBS (graphene nanoplatelet–sodium dodecylbenzene sulfonate) for 0–0.1% solid nanoparticles mass fraction was investigated for Reynolds numbers of 50–1000 in 3D space via finite volume method. In the newly proposed microchannel design, the cooling fluid is moving in countercurrent in the upper and lower layers of the microchannels, and there are cavities and sinusoidal routes on the solid walls of the microchannel, and the presence of rectangular ribs on the flow centerline along the fluid path enhances mixing for cooling fluid and creates better heat transfer for warm surfaces. The results of this study show that this special design of the microchannel can have a substantial increase in Nusselt number and heat transfer so that in the considered geometry by adding solid nanoparticles mass fraction it is possible to increase average Nusselt number for each Reynolds number by approximately 20%. Also, the mixing of the fluid because of formation of secondary flows has a strong effect on making the temperature distribution uniform in the cooling fluid and solid bed (wall) of the microchannel, especially in the lower layer. The upper layer of the microchannel always has a lower temperature due to indirect contact with heat flux compared with the lower layer. In this study, by increasing Reynolds number and mass fraction of solid nanoparticles the Nusselt number is increased and heat resistance of the lower wall of the microchannel is reduced. Based on the investigation of flow field and heat transfer, the use of the proposed design of the microchannel is recommended for Reynolds number less than 300.

A hyperchaotic map with grid sinusoidal cavity

Based on closed-loop modulation coupling pattern and the model of sinusoidal cavity, a high-dimensional sinusoidal cavity hyperchaotic system is proposed. The number of sinusoidal cavities is controlled by the system parameters. By designing a piecewise-linear controller, the grid sinusoidal cavity attractors are obtained. The equilibrium points are theoretically analyzed through mathematical calculation. Taking the two-dimensional grid sinusoidal cavity hyperchaotic map as an example, dynamics of the system are analyzed by phase diagram, equilibrium points, Lyapunov exponents spectrum, bifurcation diagram, complexity and distribution characteristics. The results show that it has rich dynamical behaviors, including complicated phase space trajectory, hyperchaotic behavior, large maximum Lyapunov exponent and typical bifurcations. The proposed hyperchaotic map has advantages in complexity and distribution in the whole parameter space. Therefore, it has good application prospects in secure communication.

Numerical simulation of natural convection using unsteady compressible Navier-stokes equations

PurposeBoussinesq approximation is widely used in solving natural convection problems, but it has severe practical limitations. Using Boussinesq approximation, the temperature difference should be less than 28.6 K. The purpose of this study is to get rid of Boussinesq approximation and simulates the natural convection problems using an unsteady compressible Navier-Stokes solver. The gravity force is included in the source term. Three temperature differences are used namely 20 K, 700 K and 2000 K.Design/methodology/approachThe calculations are carried out on the square and sinusoidal cavities. The results of low temperature difference have good agreement with the experimental and previous calculated data. It is found that, the high temperature difference has a significant effect on the density.FindingsDue to mass conservation, the density variation affects the velocity distribution and its symmetry. On the other hand, the density variation has a negligible effect on the temperature distribution.Originality/valueThe present calculation method has no limitations but its convergence is slow. The current study can be used in fluid flow simulations for nuclear power applications in natural convection flows subjected to large temperature differences.

Multicavity formations and complexity modulation in a hyperchaotic discrete system

This paper introduces a novel and unified approach for controlling the directions and number of cavities of a two dimensional Sine ICMIC modulation map (2D-SIMM). Two controllers are added to the system for arranging the cavity fluctuations and translating the cavities respectively. Both the controllers can effectively redesign the dynamics of reproducing cavities in different directions with grid representations. The dynamics of the proposed controlled model are investigated with bifurcation, Lyapunov and FuzzyEn algorithms under various cavity formations in different directions. A relationship is established for the complexity of the phase space with the directional control and various arrangements of the sinusoidal cavities. The proposed model is overall hyperchaotic with the high complexity in the whole parameter plane. The proposed scheme is effective for a dynamical model to reproduce the self phase structure in various arrangements for the optimization and modulation of complexity.

Heat transfer augmentation in a microchannel heat sink with sinusoidal cavities and rectangular ribs

A three-dimensional numerical simulation was conducted to study the characteristics of fluid flow and heat transfer in new design of microchannel heat sink with sinusoidal cavities and rectangular ribs (MC-SCRR) for Reynolds number ranging from 100 to 800. A comparative analysis has conducted to the performance of the proposed design with related geometries such as microchannel with rectangular ribs MC-RR and microchannel with sinusoidal cavities MC-SC. The results showed that thermal performance of MC-SCRR is superior over both MC-RR and MC-SC. The new design of MC-SCRR has proved the ability to combine between two important features; large flow area which significantly reduces the pressure drop and high flow disturbances which caused by existence of ribs in the central portion of channel. The overall performance of MC-SCRR is evaluated in term of friction factor, Nusselt number and performance factor. The effect of three geometrical parameters; relative cavity amplitude (λ) relative rib width (β) and relative rib length (Γ) on the convective heat transfer and pressure drop have been investigated. The performance factor Pf for MC-SCRR with λ=0.15, β=0.13 and Γ=0.5 achieves 1.85 at Re=800.

Intracranial Ameloblastoma Arising from the Maxilla: An Interdisciplinary Surgical Approach.

Background Ameloblastomas are a rare tumor entity accounting for only 10% of all odontogenic tumors. They mostly originate from the mandible. Only a few cases are known to grow aggressively and to invade the orbit, nasal cavity, or even the brain. Patient and Methods/Case Report We present the case of a 57-year-old patient who was admitted with a huge tumor involving the nasal cavity, the left maxilla, and the anterior fossa. Histologic diagnosis was made by biopsy. A combined two-stage neurosurgical maxillofacial approach was planned. First the intracranial tumor mass was removed using bifrontal trepanation. A duraplasty was sewn in to cover the brain. In the second procedure, a combined bifrontal and midfacial approach was used by craniofacial plastic surgeons and neurosurgeons. A perisinusoidal tumor mass and retropharyngeal tumor mass was removed up to the skull base. The left orbit was completely exenterated, and a fibular bone-muscle graft was used for palatal, orbital, and facial reconstruction. The facial vein and artery were carefully prepared to feed the bone-muscle graft by end-to-end anastomoses. Conclusion Ameloblastomas are very rare slow-growing tumors that show a tendency to recur. They are responsible for only 1% of all oral tumors. Their growth can be enormous, and they can extend into sinusoidal cavities, the orbit, and the brain. Complex and extensive palliative surgery can ease the concerns of these patients and prolong their survival.

Electrohydrodynamic deformation of thin liquid films near surfaces with topography

Motivated by the use of electrostatic assist to improve liquid transfer in gravure printing, we use theory and experiment to understand how electric fields deform thin liquid films near surfaces with cavity-like topographical features. Lubrication theory is used to describe the film dynamics, and both perfect and leaky dielectric materials are considered. For sinusoidal cavities, we apply asymptotic methods to obtain analytical results that relate the film deformation to the other problem parameters. For trapezoidal-like cavities, we numerically solve evolution equations to study the influence of steep topographical features and the spacing between cavities. Results from flow visualization experiments are in qualitative agreement with the theoretical predictions. In addition to being relevant to printing processes, the model problems we consider are also of fundamental interest in and represent novel contributions to the areas of electrohydrodynamics and thin-liquid-film flows.

Investigation of vortical flow over bluff bodies with base cavities

Based on our previous research about drag reduction in term of the base cavity length using two dimensional simulations, this paper describes a numerical study of a bluff body of which the number of base cavities is successively increased and the cavity geometries are also modified to assume different shapes. Here we attempt to find an effective configuration to reduce the drag by increasing the number of base cavities. The numerical simulations examining varied number of base cavities reveal the presence of different strength of vortices in the wake zone which is the reason why the drag coefficients are distinctly different for different cases. In the case with double and triple rectangular cavities, we use the pressure contours snapshots at successive time instants to describe the wake evolution. We further investigate the effect of variable base cavity shapes for a constant cavity length at an identical time instant. A total of two different geometries of base cavities are discussed here: the rectangular and the sinusoidal cavities with sharp and rounded trailing edges, respectively. The numerical results reveal that the former is an effective drag reduction configuration which can produce a significant base pressure recovery corresponding to the strength of the vortices shown in the pressure contour figures. While the latter shows no obvious reduction in drag coefficient and a similar intensity of vortex in the wake zone compared with the unmodified case. Reductions in drag are observed for all the investigated cavity configurations, and additionally it is found that the magnitude of the reduction bears a direct relationship with the number of the cavities up to a certain minimum value.

Histochemical analyses of living mouse liver under different hemodynamic conditions by “in vivo cryotechnique”

Although the morphology and molecular distribution in animal liver tissues have been examined using conventional preparation methods, the findings are always affected by the technical artifacts caused by perfusion-fixation and tissue-resection. Using "in vivo cryotechnique" (IVCT), we have examined living mouse livers with histochemical, immunohistochemical and ultrastructural analyses. In samples prepared by IVCT, widely open sinusoids with many flowing erythrocytes were observed under normal blood circulation, and their collapse or blood congestion was seen in ischemic or heart-arrested mice. In contrast, the sinusoidal cavities were artificially dilated by perfusion-fixation, and collapsed by immersion-fixation and quick-freezing (QF) methods of resected tissues. The immunoreactivity of serum albumin and immunoglobulin G and intensity of periodic acid-Schiff-staining in hepatocytes were well preserved with the QF method and IVCT. Furthermore, following tissue resection, serum proteins were rapidly translocated into hepatocytes as demonstrated by immunoreactions on QF tissues frozen 1 or 5 min after resection. Translocation was not observed in IVCT samples, indicating that IVCT could be useful to examine cell membrane permeability of hepatocytes under different pathological conditions. Both dynamic morphology and immunodistribution of soluble components in living mouse livers, reflecting their physiological and pathological states, can be precisely examined by IVCT with higher time-resolution.

Orofacial aspergillosis in acute leukemia

The clinicopathologic characteristics of orofacial aspergillosis in thirteen hospitalized patients who developed the infection while receiving chemotherapy for acute leukemia are described. Clinically, the primary sites of infection, in decreasing order of frequency, were the paranasal sinuses, nasal cavity, mouth, and facial skin; the corresponding order for the secondary sites was orbit, nasal cavity, facial skin, and mouth. Pathologically, the fungal lesions in the nasal, oral and sinusoidal cavities were black, ulcerated, and escharotic due as a direct result of tissue destruction by the organism and an indirect result of thrombotic vascular infarction. The orbital lesions were deep red, granulomatous, and productive of proptosis and ectropion. Seven of the thirteen patients had concomitant pulmonary aspergillosis. The orofacial infections were not responsive to antifungal therapy in the absence of remission of the leukemia and restoration of depressed host defenses. In two patients who did achieve remission, the aspergillosis was controlled by the intravenous administration of amphotericin B.