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This study presents the result obtained from a series of experiments conducted in regular wave flume to assess the stability of toe protection for wall type breakwater. In the present paper, the determination of the size of the toe armour units and its cross-section for the stable design is presented. The applicability of the Brebner and Donnelly (Coast Eng Proc 1: 24, 1962) design curve for depth limited conditions is validated for a certain fixed relative foundation depth (d1/d) and wavelength (L), the significant wave height (Hs). The main aim of the tests is to know the stability of the toe armour units and % damage level for varying wave characteristics. The results are represented in non-dimensional graphs and it is observed that the maximum percentage damage observed for the depth of water 0.35 m is 5.2 %.

Traditionally, simultaneous liver kidney transplantation (SLK) has been performed using a subcostal incision for the liver allograft and a lower abdominal incision for kidney transplantation (dual incision, DI). At our institution, we performed SLK using a single subcostal incision (SI). The aim of this study was to report the outcomes of single versus dual incisions for SLK.A retrospective cohort study of consecutive SLK procedures performed at our center from January 2015 to April 2021 was performed. The demographic characteristics, complications, intraoperative findings, and complications after SI and DI were statistically compared.A total 37 SLK were performed (19 DI and 18 SI). The age and indications for transplantation were comparable between the two groups. Patient in SI group had significantly higher MELD score (27.0 ± 1.5 vs. 31.7 ± 1.5, p = .038). The cold ischemic time of kidney transplantation (599 ± 26 min vs. 447 ± 27 min, p .001) and the total surgical time (508 ± 21 min vs. 423 ± 22 min, p = .008) were significantly shorter in the SI group. The incidence of complications and post-transplant kidney function was comparable between the groups. A slightly higher incidence of surgical site complications was noted in the DI group without any statistically significance (p = .178).Single-subcostal incision SLK is technically feasible and has comparable outcomes to dual-incision SLK. SI was associated with shorter cold ischemic time for kidney transplant, as well as shorter overall operative time.

Background Combined heart-liver transplantation (CHLT) is the only curative option for patients with concomitant pathology affecting the heart and liver. In some cases, the native livers of familial amyloidosis (FA) patients may be suitable for domino transplantation into other recipients. Methods Retrospective analysis (2013 to 2019) of all CHLT at our center was performed. Continuous data were presented as mean with standard deviation and discrete variables as percentages. Results Familial amyloidosis was the indication for CHLT in 5 out of 6 patients. The mean recipient age was 55 ± 5.62 years. Two patients were bridged with total artificial heart. The mean model for end-stage liver disease score at transplant was 17.17 ± 3.7. Two explanted livers were used for transplantation in a domino fashion. The median intensive care and hospital stays were 5.5 and 19 days, respectively. Complications included renal failure (1), groin abscess (1), pulmonary embolism (1), and cardiac rejection (1). Patient and graft survival for both organs was 100% at a median follow-up of 59 (range 20-76) months. Discussion Combined heart-liver transplantation for FA achieves excellent outcomes. The possible use of livers explanted from patients with FA for domino liver transplantation can contribute to the liver donor pool.

Background: Trauma victims with liver lacerations in the hilum are typically excluded from liver donation. We report a case of a successful liver transplant from a deceased donor with a grade 4 hilar liver laceration. Case Presentation: We used a liver with a high-grade laceration from a 28-year-old brain-dead traffic accident victim. The liver had grade IV lacerations in the right and caudate lobes. In situ split liver technique was applied to control the lacerations after an intraoperative cholangiogram revealed favourable anatomy. The left hemi-liver graft was procured, retaining the entire vena cava and the full length of the main hepatic vasculature. The recipient was a 62-year-old female patient with end-stage liver disease, with a Model for End-Stage Liver Disease-Sodium score of 19. The left lobe graft was transplanted using the standard piggy-back technique. The patient was discharged on postoperative day 7 after an uneventful recovery. At two-month follow-up, she continues to do well, with normal hepatic function and unremarkable imaging studies. Conclusion: This is the first reported case of a successful liver transplant of a severely lacerated liver made possible by the application of split liver techniques. In situ splitting of a severely traumatized liver could permit the utilization of a reduced graft for small recipients.

Hepatic artery aneurysms are rare, but their diagnosis is important because of high mortality and complications. Common risk factors for developing these aneurysms include hypertension, vascular disease, pancreatitis, diabetes, tobacco use, autoimmune diseases, and previous transplantation. Frequent imaging for trauma and tumor surveillance has increased the incidence of naive hepatic aneurysms. These aneurysms can be difficult to manage, and it can be challenging to decide the correct treatment modality for the patient. Hereby, we present four cases of hepatic artery aneurysm and discuss various treatment options. Patient 1 suffered from a proper and right hepatic artery aneurysm discovered incidentally; repaired with an endovascular intervention later complicated by an endoleak which was further managed by another stenting. Patient 2 had a common hepatic artery aneurysm followed with serial imaging without any intervention. Patient 3 had a hepatic artery aneurysm and liver mass diagnosed concurrently. The patient underwent an open surgical repair of his aneurysm with graft and liver resection which was complicated later with rupture of aneurysm followed by surgical bypass repair. Patient 4 suffered from a large hepatic artery aneurysm causing bile duct compression. Her aneurysm was repaired open with splenic artery grafting. Patients were managed from careful observation to surgery with different outcomes.

The combinatorial influence of a biophysical cue (substrate stiffness) and biomechanical cue (shear flow) on the osteogenesis modulation of human mesenchymal stem cells (hMSCs) is studied for bone regenerative applications. In this work, we report stem cell differentiation on an ultra high molecular weight polyethylene (UHMWPE)-based hybrid nanobiocomposite [reinforced with a multiwalled carbon nanotube (MWCNT) and/or nanohydroxyapatite (nHA)] under a physiologically relevant shear flow (1 Pa) in a custom-built microfluidic device. Using a genotypic assessment with qRT-PCR and phenotypic assessment through analysis of cytoskeletal remodelling and marker proteins, the role of shear on the progression of osteogenesis modulation has been quantitatively established with statistically significant differences between nHA-reinforced and MWCNT-reinforced UHMWPE. Early-stage (alkaline phosphatase activity at day 8), middle-stage (matrix collagenation at day 14), and late-stage (matrix calcification at day 20) events were analyzed using mRNA expression changes of a limited cell volume after microfluidic culture experiments. The conventional Petri dish culture (static) exhibited an increased osteogenesis for nanoparticle-reinforced UHMWPE, irrespective of the type of nanoparticle. The shear-mediated culture experiments resulted in noticeable differences in the degree of osteogenesis with MWCNT being more effective than nHA reinforcement. The shear-mediated osteogenesis has been attributed to the skewed cellular morphology with a higher cell adhesion (vinculin expression) on UHMWPE and nHA than that of UHMWPE and MWCNT. The signatures of the cytoskeletal changes are reflected in terms of left-to-right (L-R) chirality as well as alignment and pattern of actin fibers. Moreover, stemness (vimentin expression) was found to be decreased because of differentiation. The electrophysiological analysis using patch clamp experiments also revealed a higher inward calcium current and intracellular calcium activity for the cells grown on the UHMWPE and nHA nanobiocomposite under shear. Overall, the present study conclusively establishes the synergistic role of substrate stiffness and shear on osteogenesis of hMSCs, in vitro.

The mechanisms of destabilisation of the flow through soft-walled channels/tubes are qualitatively different from those in rigid-walled conduits. The stability depends on two dimensionless parameters, the Reynolds number $(\rho _f V_f h_f/ \mu _f)$ and $\varSigma = (\rho _f G h_f^{2}/\mu _f^{2})$ , where $\rho _f$ and $\mu _f$ are the fluid density and viscosity, $h_f$ and $V_f$ are the fluid length and velocity scale and $G$ is the wall elasticity modulus. There is an instability at zero Reynolds number when the dimensionless parameter $\varGamma = (\mu _f V_f / h_f G)$ exceeds a critical value. The low-Reynolds-number instability of the Couette flow past a compliant surface is well understood, and has been confirmed in experiments, but that in a pressure-driven flow is not completely understood. Two modes of instability at high Reynolds number have been predicted: the inviscid mode with an internal viscous layer, for which the transition Reynolds number scales as ${Re}_t \propto \varSigma ^{1/2}$ ; and the wall mode instability with a viscous layer at the wall, for which ${Re}_t \propto \varSigma ^{3/4}$ . The wall mode instability has been observed in experiments at Reynolds number as low as 300 in a soft-walled tube and as low as 100 in a channel with one compliant wall, though the scaling of the transition Reynolds number differs from the theoretical prediction due to substantial wall deformation. Though the flow after transition shares many of the characteristics of hard-wall turbulence, it differs in significant ways, suggesting that soft-wall turbulence is a separate class distinct from hard-wall turbulence.

In this paper sharp bounds for the probability of union of n arbitrary events following unknown probability distribution are found, when only $$m(m < n)$$ out of n binomial moments of the events are given. The bounds are found using a class of special matrices and their inverses. Generalized closed form probabilistic bounds are found for the probability of occurrence of at least r out of n events by using the same class of matrices and their inverses. In numerical examples section the parameter r is studied and tables are given to depict the effect of r over the sharp bounds. As an application, MAXSAT problem is also discussed and the effect of using relatively higher binomial moments over the chance of having the optimal upper bound less than 1 is discussed.

The steady-state magneto-mechanical response of a magnetorheological fluid (MRF), prepared by dispersing 40 wt % of magnetically soft, light-weight coral-network-shaped yttrium iron garnet (YIG; Y3Fe5O12) powder in silicone oil (140 cSt) is studied as a function of shear rate, under different applied magnetic fields (B). The results show that the yield strength (tau(Y)) and viscosity (eta) of the MRF increase with B, and are strongly influenced by the physical parameters of the particles such as morphology and saturation magnetization. The low density of the YIG-particles, leading to higher volume fraction for equal mass loading, results in a higher viscosity in the absence of a magnetic field, in comparison to that of conventional metallic Fe-particle-based MRFs. Due to this, there is a relatively smaller increase in tau(Y) and eta when the magnetic field is switched on. The YIG-particles-based MRF has the advantages of high chemical stability, thermo-oxidative resistance and low-cost.

Manganese-zinc ferrite (Mn0.7Zn0.3Fe2O4) powder containing irregular-shaped particles with high saturation magnetization and high magnetic softness was synthesized via solution combustion method. By dispersing these magnetic ceramic particles in silicone oil, a magnetorheological fluid (MRF) was prepared and its magneto-mechanical property was studied. The yield strength ((Y)) exhibited by the MRF increases with increase in applied magnetic field, and a very high value of yield strength of similar to 10.5kPa (at B=1.2T) was observed. The viscosity () of the MRF also increases with B due to increased inter-particle magnetic interaction. The low density, low cost of the precursors and the industrial scalability of the Mn-Zn ferrite powder-production render these powders suitable for large-scale device applications. In addition, the thermal, oxidative and chemical stabilities of these ferrimagnetic oxide ceramics are advantageous for their application in corrosive and high temperature environments.

Magnetorheological fluids have tunable magneto-mechanical strength. We report the magneto-mechanical (steady-state shear) response of magnetorheological fluids (MRFs) containing bi-disperse Mn-Zn ferrite (Mn0.7Zn0.3Fe2O4) spherical particles synthesized by a solvothermal method. Using a model of magnetic dipolar interactions between the particles, we have explained the origin of the magneto-mechanical response of the MRFs. The observed yield strength values of our MRFs increase with the applied magnetic field strength and the concentration of the ferrite particles in the fluid due to the formation of strong columnar structures which resist the shear. Moreover, the yield strength of the MRFs was found to depend strongly on the particle size, size distribution and the magnetic nature (saturation) of the particles. We have demonstrated that a bi-disperse size distribution of particles in the fluid imparts superior yield strength to the MRF compared to that of the mono-disperse particles. Unlike conventional metallic iron particles, which lead to dispersion instability and are prone to corrosion and thermo-oxidative failures, the low-density corrosion-resistant soft-ferrimagnetic Mn-Zn ferrite particles make our MRF system dependable for various technological applications demanding shock absorption and vibration isolation.

BACKGROUND Reconstruction of the hepatic arterial inflow can be technically demanding in living donor liver transplantation, and thrombosis can result in graft loss and mortality. We describe the safe and reproducible "W" technique to reconstruct the hepatic artery and outcomes before and after adoption of the technique in a consecutive series of liver transplants at 2 high-volume living donor liver transplant centers. MATERIAL AND METHODS Prospectively collected data were analyzed to compare the outcomes before and after introduction of a standardized "W" technique for reconstruction of the hepatic artery in 2 high-volume living donor liver transplant programs. RESULTS In a consecutive series of 675 liver transplants, of which 27 were deceased donor transplants and 648 were living donor transplants, 443 transplants were performed with a standard interrupted reconstruction of the hepatic artery under loupes. These transplants were performed by a single surgeon, with an incidence of hepatic artery thrombosis of 2%. After introduction of the "W" technique, despite the arterial reconstruction being done by several surgeons in the early part of their learning curve, the incidence of hepatic artery thrombosis decreased to 0.86% in the next 232 transplants. CONCLUSIONS The "W" technique is a simple, easy to learn and teach technique for reconstruction of the hepatic artery without the use of the operating microscope in living donor liver transplantation.

One of the central themes in cell and tissue engineering is to develop an understanding as to how biophysical cues can influence cell functionality changes. The flow induced shear stress is regarded as one such biophysical cue to influence physiological changes in shear-sensitive tissues, in vivo. The origin of such phenomena is, however, poorly understood. While addressing such an issue, the present work demonstrates the intriguing synergistic effect of shear stress and spatial constraints in inducing aligned growth and differentiation of myoblast cells to myotubes. In a planned set of in vitro experiments, the regulation of laminar flow regime within a narrow window was obtained in a PMMA-based Lab-on-Chip (LOC) device, wherein the murine muscle cells (C2C12), chosen for their phenotypical differentiation stages, were cultured under graded shear conditions. The two factors of shear stress and spatial allowance were decoupled by another two sets of experiments. This aspect has been conclusively establish...

For the design and construction of a vertical-caisson breakwater which is more significant task in the field of ocean engineering, since the incidicent wave and reflected wave acting on the structure causes severe bottom scouring and final leads to failure of the structure. The influences of wave height, wave period, and toe armor unit stability are under investigation in this study. The experimental work conducted by Brebner and Donnelly [1], was put forward, that for a certain fixed relative foundation depth (d1/d) and wavelength (L), the significant wave height (Hs), will have an exponential relationship with the number of rocks displaced in the armor layer of the toe of the vertical-caisson structure. The investigation are conducted in the regular 2D wave flume at wave mechanics laboratory, NITK, Surathkal. The present paper provides the required information regarding the damage level of toe armor units in transition water depths and the effect of wave parameters are analyzed.

When a suspension of conducting particles is subjected to a shear flow, there is particle rotation due to the fluid vorticity. A conductor rotating in a uniform magnetic field experiences a torque due to eddy currents both parallel and perpendicular to the direction of rotation. Eddy currents induce a magnetic moment in a conducting particle, which disturbs the magnetic field around the particle. The effect of the Maxwell stress due to the magnetic field disturbance on the rheology of a dilute suspension is calculated in a manner similar to the Einstein viscosity for a suspension of rigid particles. The expression for the stress tensor contains three symmetric stress coefficients, and two normal stress coefficients, in addition to the three antisymmetric stress coefficients calculated in Kumaran (J. Fluid Mech., vol. 871, 2019, pp. 139–185). The stress coefficients depend on the relative orientation of the vorticity and magnetic field and two dimensionless parameters, , the product of the vorticity and current relaxation time, and , the ratio of the magnetic and hydrodynamic torques. In the ‘linear’ approximation, where only terms linear in the particle magnetic moment are retained, the particle stress depends on two dimensionless functions. For the physically important limit , as well as the limit and , these two functions are independent of the vorticity, and depend only on the magnetic field and material properties.

The modification of fluid turbulence due to suspended particles is analysed using direct numerical simulations for the fluid turbulence and discrete particle simulations where the point-particle approximation is used for the particle force on the fluid. Two values of the Reynolds number based on the channel width at the critical volume fraction. There is no compensatory increase in the particle fluctuating velocities or the energy dissipation rate due to the drag force on the particles, and there is a significant decrease in the total fluid energy dissipation rate at the critical volume fraction. This shows that the turbulence collapse is due to a catastrophic reduction in the turbulent energy production rate. This is contrary to the current understanding that turbulence attenuation is caused by the enhanced dissipation due to particle drag.

We report the steady-state shear response of polydisperse Ni-Zn ferrite-submicrospheres-based magnetorheological fluids (MRFs). The Ni-Zn ferrite spherical particles were prepared by solvothermal method. MRFs of three different concentrations (10, 20 and 40 wt%) were prepared by dispersing Ni-Zn ferrite submicrospheres in silicone oil. These MRFs were subjected to steady-state shear conditions, at different applied magnetic fields. Dynamic yield strength values corresponding to different applied field strengths showed increase in value with increase in magnetic field strength. Furthermore, the dynamic yield strength scaled up with the concentration of Ni-Zn ferrite spherical particles in the carrier fluid. Comparison of the dynamic yield strengths for the MRFs showed that the values depend strongly on the physical properties of the particles such as the particle size, size-distribution (polydispersity) and the saturation magnetization. (C) 2018 Elsevier B.V. All rights reserved.

Carbon globules embedded with magnetic iron/iron carbide nanoparticles were synthesized by pyrolysis route using different organic solvents (benzene/toluene/xylene) along with ferrocene as iron catalyst precursor. All other synthesis parameters were kept constant (e.g. reaction temperature ≈ 950 oC, heating rate of 3 oC/min). We observed a variation of magnetic phase composition with the type of solvent (carbon source) used for synthesis, although the morphology of all the samples was similar. Improved sample crystallinity, distribution of particles and saturation magnetization were obtained, when toluene was used as solvent. Interestingly, rod shaped magnetic particles were observed in case of benzene, whereas for toluene and xylene, all iron-based magnetic particles were spherical. Due to higher saturation magnetization, we have used the particles prepared using toluene as a solvent to demonstrate the magnetorheological behaviour of these carbon-coated magnetic nanoparticles. We observed good magneto-response for the samples suggesting that these particles are potential candidate for magnetorheological applications.

The biophysical cues of endogenous origin, i.e., shear stress and electric field, are known to significantly modulate cell functionality, in vitro. While this has been relatively well investigated in conventional petri dish culture, it is important to validate such important phenomenon in physiologically simulated cellular microenvironment. In this perspective, this review critically discusses the importance of lab-on-a-chip (LOC)-based microfluidic devices to probe into this aspect to develop an insight towards the application in regenerative medicine. While reviewing several literature reports, an emphasis has been placed to unravel the intriguing aspects of shear and electric field modulated differentiation of stem cells in the biomicrofluidics devices. The potential application focusing the stem cell culture was emphasized in this article as the stem cells are the foundation of tissue regeneration. Several challenges in tissue regeneration and introduction of personalized medicine could be addressed through microfluidic technology. Culturing of organ-specific multiple cell types within lab-on-a-chip and biophysical stimulation mediated activations of intracellular signal transduction under gradient shear/electric field are highlighted in this review. Lay Summary: Conceptually, regenerative medicine is considered as an emerging approach for treating traumatized, malfunctional anatomical parts of the patients with stem cells to establish normal functionality of the tissue. The regenerated tissue should preferably be the patients� autologous tissue, grown under artificially created in vivo physiological environment. Biomicrofluidic-based lab-on-a-chip technology enables to perform in vitro cell/tissue engineering under endogenous cues, like shear and electric field. Therefore, this review discusses two aspects of regenerative medicine in terms of autologous transplantation of cells/tissues to improvise personalized regenerative medicine and to recreate an organ-specific tissue under the influence of biophysical stimulation in an attempt to improve the physiological functionality.

Sharp bounds in terms of the first few binomial moments are found for the probability of a union of events, when the random variable denoting the number of events that occur follows symmetric distribution. Connection between the bounds of this paper and the bounds from a special case of the binomial moment problem of Prekopa (1995) is shown. As a special case, bounds for the probability when the underlying probability distribution is unimodal-symmetric are also found.

We report the synthesis of single crystalline octahedron-shaped magnetite microcrystals, the preparation of magnetorheological fluids (MRFs) and their magnetorheological properties under steady-state shear conditions. The magnetite microcrystals were synthesized via the template-free hydrothermal route. MRFs with three different particle concentrations (10, 20 and 40 weight%) were prepared and were subjected to steady shear conditions at various externally applied magnetic fields of strength up to 1.2 T. The shear rates were chosen up to high enough values to observe the yield behaviour of the MRFs. The dynamic yield strengths of MRFs, estimated using the Bingham plastic model fit to the steady-state shear response curves, showed that they scale-up with the applied magnetic field strength and amount of magnetic particles in the fluid. The origin of the mechanical strength in the MRFs due to the inter-particle interaction is explained using a simple dipolar model. The observed high yield strengths of the MRFs were explained on the basis of the particle shape (octahedrons) and magnetic nature (saturation magnetization). By comparing the values of the yield strength with the on-state to off-state viscosity ratio for the MRFs (for each particle concentration), an optimum content of particles in the carrier fluid to obtain high efficiency is suggested. Because the particles are single crystalline, the off-state viscosity of the MRFs even at the highest studied (40 wt%) particle concentration was very low, which is ideal for their application as quickly responding MRFs.

Sharp bounds for the probability of occurrence of at least one out of n events are found when the probability distribution of the occurrences is supposed to follow monotonic distribution and first m(mn1) binomial moments are known. The bounds are found explicitly for two different cases of increasing and decreasing distributions using operations research techniques. Inverses are found for two different classes of matrices and the bounds are obtained using those inverses.

When a suspension of conducting particles is sheared in a magnetic field, the fluid vorticity causes particle rotation. Eddy currents are induced in a conductor rotating in a magnetic field, resulting in magnetic moment, and a magnetic torque due to the external field. In the absence of inertia, the angular velocity of a particle is determined from the condition that the sum of the hydrodynamic and magnetic torques is zero. When the particle angular velocity is different from the fluid rotation rate, the torque exerted by the particles on the fluid results in an antisymmetric particle stress. The stress is of the form $\unicode[STIX]{x1D748}^{(p)}=|\unicode[STIX]{x1D74E}|(\unicode[STIX]{x1D702}_{c}^{(1)}(\hat{\unicode[STIX]{x1D750}}\boldsymbol{ : }\hat{\unicode[STIX]{x1D74E}})+\unicode[STIX]{x1D702}_{c}^{(2)}\hat{\unicode[STIX]{x1D750}}\boldsymbol{ : }(\hat{\boldsymbol{H}}-\hat{\unicode[STIX]{x1D74E}}(\hat{\unicode[STIX]{x1D74E}}\boldsymbol{\cdot }\hat{\boldsymbol{H}}))/(\sqrt{1-(\hat{\unicode[STIX]{x1D74E}}\boldsymbol{\cdot }\hat{\boldsymbol{H}})^{2}})+\unicode[STIX]{x1D702}_{c}^{(3)}(\hat{\unicode[STIX]{x1D74E}}\hat{\boldsymbol{H}}-\hat{\boldsymbol{H}}\hat{\unicode[STIX]{x1D74E}})/\sqrt{1-(\hat{\unicode[STIX]{x1D74E}}\boldsymbol{\cdot }\hat{\boldsymbol{H}})^{2}})$, where $\unicode[STIX]{x1D74E}$ is the fluid vorticity at the centre of the particle, $\hat{\unicode[STIX]{x1D74E}}$ and $\hat{\boldsymbol{H}}$ are the unit vectors in the direction of the fluid vorticity and the magnetic field, $\hat{\unicode[STIX]{x1D750}}$ is the third order Levi-Civita antisymmetric tensor and $\unicode[STIX]{x1D702}_{c}^{(1)}$, $\unicode[STIX]{x1D702}_{c}^{(2)}$ and $\unicode[STIX]{x1D702}_{c}^{(3)}$ are called the first, second and third couple stress coefficients. The stress proportional to $\unicode[STIX]{x1D702}_{c}^{(1)}$ is in the plane perpendicular to $\hat{\unicode[STIX]{x1D74E}}$, that proportional to $\unicode[STIX]{x1D702}_{c}^{(2)}$ is in the plane perpendicular to the unit normal to $\hat{\unicode[STIX]{x1D74E}}$ in the $\hat{\unicode[STIX]{x1D74E}}{-}\hat{\boldsymbol{H}}$ plane, and that proportional to $\unicode[STIX]{x1D702}_{c}^{(3)}$ is in the $\hat{\unicode[STIX]{x1D74E}}{-}\hat{\boldsymbol{H}}$ plane. A relation $\unicode[STIX]{x1D702}_{c}^{(2)}=-(\hat{\unicode[STIX]{x1D74E}}\boldsymbol{\cdot }\hat{\boldsymbol{H}}\unicode[STIX]{x1D702}_{c}^{(1)}/\sqrt{1-(\hat{\unicode[STIX]{x1D74E}}\boldsymbol{\cdot }\hat{\boldsymbol{H}})^{2}})$ results from the condition that the component of the eddy current torque along the magnetic field is zero. The couple stress coefficients are obtained for two geometries, a uniform spherical particle of radius $R$ and a thin spherical shell of radius $R$ and thickness $\unicode[STIX]{x1D6FF}R$ with $\unicode[STIX]{x1D6FF}\ll 1$, in the dilute (non-interacting) limit in the absence of fluid inertia. These couple stress coefficients are functions of two dimensionless parameters, $\unicode[STIX]{x1D6F4}=(\unicode[STIX]{x1D707}_{0}H_{0}^{2}/4\unicode[STIX]{x03C0}\unicode[STIX]{x1D702}|\unicode[STIX]{x1D74E}|)$, the ratio of the characteristic magnetic and hydrodynamic torques, and $\unicode[STIX]{x1D6FD}$, the product of the vorticity and current relaxation time. Here $\unicode[STIX]{x1D707}_{0}$ is the magnetic permeability, $H_{0}$ is the magnetic field and $\unicode[STIX]{x1D702}$ is the fluid viscosity. The parameter $\unicode[STIX]{x1D6FD}$ has the form $\unicode[STIX]{x1D6FD}_{p}=(|\unicode[STIX]{x1D74E}|\unicode[STIX]{x1D707}_{0}R^{2}/2\unicode[STIX]{x1D71A})$ for a uniform particle and $\unicode[STIX]{x1D6FD}_{s}=(|\unicode[STIX]{x1D74E}|\unicode[STIX]{x1D707}_{0}R^{2}\unicode[STIX]{x1D6FF}/2\unicode[STIX]{x1D71A})$ for a thin shell, where $\unicode[STIX]{x1D71A}$ is the electrical resistivity. Scaled couple stress coefficients are defined, $\unicode[STIX]{x1D702}_{1}^{\ast }=(\unicode[STIX]{x1D702}_{c}^{(1)}/((3\unicode[STIX]{x1D702}\unicode[STIX]{x1D719}/2)(1-(\hat{\unicode[STIX]{x1D74E}}\boldsymbol{\cdot }\hat{\boldsymbol{H}})^{2})))$ and $\unicode[STIX]{x1D702}_{3}^{\ast }=(\unicode[STIX]{x1D702}_{c}^{(3)}/((3\unicode[STIX]{x1D719}\unicode[STIX]{x1D702}/2)\hat{\unicode[STIX]{x1D74E}}\boldsymbol{\cdot }\hat{\boldsymbol{H}}\sqrt{1-(\hat{\unicode[STIX]{x1D74E}}\boldsymbol{\cdot }\hat{\boldsymbol{H}})^{2}}))$, which are independent of the fluid viscosity and the particle volume fraction, and which do not depend on $\hat{\unicode[STIX]{x1D74E}}$ and $\hat{\boldsymbol{H}}$ in the limits $\unicode[STIX]{x1D6F4}\ll 1$ and $\unicode[STIX]{x1D6F4}\gg 1$. Here, $\unicode[STIX]{x1D719}$ is the volume fraction of the particles. Asymptotic analysis is used to determine the couple stress coefficients in the limits $\unicode[STIX]{x1D6F4}\ll 1$ and $\unicode[STIX]{x1D6F4}\gg 1$, and a numerical solution procedure is formulated for $\unicode[STIX]{x1D6F4}\sim 1$. For $\unicode[STIX]{x1D6F4}\ll 1$, the particle angular velocity is aligned close to the fluid vorticity, and the scaled couple stress coefficients are $\unicode[STIX]{x1D6F4}$ times a function of $\unicode[STIX]{x1D6FD}$. For $\unicode[STIX]{x1D6F4}\gg 1$, the particle angular velocity is aligned close to the magnetic field, $\unicode[STIX]{x1D702}_{1}^{\ast }\rightarrow 1$ and $\unicode[STIX]{x1D702}_{3}^{\ast }\propto \unicode[STIX]{x1D6F4}^{-1}$. When the magnetic field is perpendicular to the fluid vorticity, $\hat{\unicode[STIX]{x1D74E}}\boldsymbol{\cdot }\hat{\boldsymbol{H}}=0$, the particle angular velocity is aligned along the vorticity, and only the first couple stress coefficient is non-zero. For high $\unicode[STIX]{x1D6FD}$, there are multiple solutions for the couple stress coefficient. Multiple steady states are also observed for a near perpendicular magnetic field, $\hat{\unicode[STIX]{x1D74E}}\boldsymbol{\cdot }\hat{\boldsymbol{H}}, for a reason different from that for a perpendicular magnetic field. Asymptotic analysis is used to explain the existence of multiple steady states in both cases.

A number of bioengineering strategies, using biophysical stimulation, are being explored to guide the human mesenchymal stem cells (hMScs) into different lineages. In this context, we have limited understanding on the transdifferentiation of matured cells to another functional-cell type, when grown with stem cells, in a constrained cellular microenvironment under biophysical stimulation. While addressing such aspects, the present work reports the influence of the electric field (EF) stimulation on the phenotypic and functionality modulation of the coculture of murine myoblasts (C2C12) with hMScs [hMSc:C2C12=1:10] in a custom designed polymethylmethacrylate (PMMA) based microfluidic device with in-built metal electrodes. The quantitative and qualitative analysis of the immunofluorescence study confirms that the cocultured cells in the conditioned medium with astrocytic feed, exhibit differentiation towards neural-committed cells under biophysical stimulation in the range of the endogenous physiological electric field strength (8 ± 0.06 mV/mm). The control experiments using similar culture protocols revealed that while C2C12 monoculture exhibited myotube-like fused structures, the hMScs exhibited the neurosphere-like clusters with SOX2, nestin, βIII-tubulin expression. The electrophysiological study indicates the significant role of intercellular calcium signalling among the differentiated cells towards transdifferentiation. Furthermore, the depolarization induced calcium influx strongly supports neural-like behaviour for the electric field stimulated cells in coculture. The intriguing results are explained in terms of the paracrine signalling among the transdifferentiated cells in the electric field stimulated cellular microenvironment. In summary, the present study establishes the potential for neurogenesis on-chip for the coculture of hMSc and C2C12 cells under tailored electric field stimulation, in vitro.

Liver transplantation (LT) for hepatocellular carcinoma (HCC) has evolved from contraindication in the early 1990s to one of the common indications in today’s era. A lot of credit goes to the Milan criteria (1 lesion up to cm, 2–3 lesions up to 3 cm) for setting up this bench mark based on the seminal publication by Mazzaferro et al. nearly two decades ago [1]. LT provides a good 4-year survival rates (actuarial rate 74%) with low recurrence rates (recurrence-free survival rate of 83%) if performed for HCC within these criteria [1]. Liver transplant (LT) has a dual advantage as treatment; it is not only oncologically the best operation but it also cures the underlying cirrhosis. In view of longer wait times (due to shortage of organs) and high dropout rates (tumour progression/death), the practice of bridging (locoregional) therapy is becoming an essential part of HCC treatment. In this chapter we will discuss available evidence on the efficacy of bridging therapy for HCC. We will also discuss the current role of downstaging in the management of HCC. Towards the end we would like to highlight the role of bridging therapy in Indian scenario and also touch upon guidelines from Asian countries.

Liver transplantation has become common in India over the last decade and biliary strictures after the procedure cause a significant morbidity. Endoscopic retrograde cholangiopancreatography (ERCP) is a safe and effective treatment modality for post-transplant biliary strictures so we decided to evaluate prospectively the outcomes of endoscopic treatment in post-living donor liver transplantation (LDLT) biliary strictures. We studied ten consecutive patients who had developed biliary strictures (out of 312 who had undergone liver transplantation between June 2009 and June 2013) and had been referred to the Department of Gastroenterology for management. All patients underwent liver function tests, ultrasound of the abdomen, magnetic resonance cholangiography and liver biopsy, if this was indicated. Of these 312 patients who underwent liver transplantation, 305 had living donors (LDLT) and 7 deceased donors (DDLT). Ten patients in the LDLT group (3.3 %) developed biliary strictures. There were seven males and three females who had median age of 52 years (range 4–60 years). The biliary anastomosis was duct-to-duct in all patients with one patient having an additional duct-to-jejunum anastomosis. The mode of presentation was cholangitis in four patients (40 %), asymptomatic elevation of liver enzymes in four (40 %) and jaundice in two patients (20 %). The median time from transplantation to the detection of the stricture was 12 months (2–42.5 months). ERCP was attempted as initial therapy in all patients: seven were managed entirely by endoscopic therapy, and three required a combined percutaneous and endoscopic approach. Cholangiography demonstrated anastomotic stricture in all patients. A total of 32 sessions of ERCP were done with mean of 3.2 (2–5) endoscopic sessions and 3.4 (1–6) stents required to resolve the stricture. The median time from the first intervention to stricture resolution was 4 months (range 2–12 months). In four patients, the stents were removed after one session and in two patients each after two, three and four sessions. In six patients more than one stent was placed and all of them required dilatation of stricture. Seven patients completed treatment and are off stents at a median follow up period of 9.5 months (7–11 months). Two patients developed recurrence of their stricture after 7.5 months. Both had long strictures and required a combined endoscopic and percutaneous approach. There was one mortality due to sepsis secondary to cholangitis. Post-LDLT biliary strictures can be successfully treated with ERCP, and most patients remain well on follow up (median 9.5 months). A combined endoscopic and percutaneous approach is useful when ERCP alone fails.

A number of experimental studies have established the critical role of electric field stimulation on cell functionality modulation of various cell types on a wide range of biomaterial platforms in vitro. In particular, cell fate processes, morphological changes and electroporation are significantly modulated over a narrow range of electric field stimulation conditions. Although a few studies using electrical network theory, first principle simulations and electrohydrodynamic models are reported in the literature, the present study establishes a theoretical foundation to a new perspective that bioelectric stress can significantly influence cell morphological changes/electroporation and in a broader sense, the cell response to electric field on biomaterial substrates. A single cell is modelled as a spherical membrane separating the culture medium and the cytoplasm having different dielectric properties. The analytical solutions to the Laplace equation and Poisson equation for the system are adopted to quantitatively capture the potential distribution in the cellular microenvironment for different cases. These include a cell on a conducting substrate, on an insulating substrate and a cell with surface charge density, in electric field stimulated cellular microenvironment. The biophysical significance of the normal stress distribution has been discussed in terms of the variation in the cellular deformation, depending on the frequency of the electric field and substrate conductivity. A significant difference has been observed in the deformation behavior at higher frequencies ( > 10 9 Hz) compared to low frequency and DC electric fields. This theoretical study therefore unravels the significance of substrate conductivity in synergy with electric field parameters to modulate cell response. In addition, the tangential component of the Maxwell stress tensor (shear stress), a measure of the stretching force on the membrane, has been used to obtain estimates of the critical electric field required for membrane rupture. It has been predicted that a cell with surface charge density requires electric fields of the order of 10 kV/mm in order to undergo membrane rupture, which is in line with the experimental observations reported in the literature. Taken together, the presented analysis is expected to provide guidelines to develop next generation biomaterials and biomedical devices for regenerative medicine and cancer treatments.

Steady shear response of a magnetorheological fluid (MRF) system containing porous mono-disperse magnetite (Fe3O4) spheres synthesized by solvothermal method is demonstrated. In applied magnetic field the interaction between the spherical particles leads to form strong columnar structures enhancing the yield strength and viscosity of the MRFs. The yield strengths of the MRFs also scale up with the concentration of magnetic particles in the fluid. Considering magnetic dipolar interaction between the particles the magneto-mechanical response of the MRFs is explained. Unlike metallic iron particles, the low-density corrosion resistant soft-ferrimagnetic Fe3O4 spherical particles make our studied MRF system efficient and reliable for shock-mitigation/vibration-isolation applications. (C) 2018 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Magnetically soft nickel-zinc ferrite (Ni0.5Zn0.5Fe2O4) powder with high saturation magnetization was synthesized by solution combustion route using metal nitrates as precursors and glycine as fuel. The particles were found to have irregular morphology. Three different concentrations of magnetorheological fluids (MRFs) were prepared by dispersing 10, 20 and 40 wt% of these particles in thin silicone oil. The behaviours of the MRFs were studied under steady shear conditions at different applied magnetic field strengths (B). The yield strength (tau(Y)) and viscosity (eta) of all the MRFs were found to increase with B and particle fill fraction phi, while the response of the MRFs was strongly influenced by the morphology, microstructure and saturation magnetization of the particles. Owing to the low density of the particles, the observed off-state viscosity is high. However, the excellent thermo-oxidative and chemical stabilities of these magnetic oxide particles than metallic magnetic particles make these MRFs dependable for applications in harsh working environments. In addition, the low cost and feasibility of large scale preparation of these magnetic oxides make these MRFs further attractive for industrial applications. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

We report the magnetic field and particle-concentration dependent steady-state shear-responses of rod shaped Li-Zn ferrite particle based magnetorheological fluids (MRFs). Rod-shaped soft ferrimagnetic Li-Zn ferrite (Li0.4Zn0.2Fe2.4O4) particles were synthesized using the combustion synthesis method. MRFs of three different particle-concentrations (phi = 0.1, 0.2 and 0.4, in weight fraction) were prepared using silicone oil. Their yield strength and dynamic viscosity were studied at different applied magnetic fields (B). With an increase in B and phi, the yield strength ((Y)) of the MRFs increases. This behaviour is assigned to the formation of stronger columnar structures of the magnetically interacting particles which resist the flow (shear) of the MRF. For the MRF with phi = 0.4 and B = 1.2 T, we observed a maximum (Y) value of approximate to 1.25 kPa. Furthermore, we observed that, based on the on-state to off-state viscosity ratio ((on)/(off)) at a particular operating B value, the optimum particle concentration required for energy- and cost-efficient operation of the MRFs can be chosen. The absence of a stabilizing-agent or de-agglomerating-coating, the low density, and the excellent oxidation- and corrosion-resistance of the soft ferrimagnetic rod-shaped Li-Zn ferrite particles make this MRF-system highly versatile and economical for many magneto-mechanical applications.

Abernethy malformation is a rare congenital anomaly in which there is direct communication between the portal and systemic venous circulation. The clinical presentation ranges from asymptomatic with incidental detection on imaging to secondary complications of disease or related to associate anomalies. This is a retrospective analysis of data from nine patients with Abernethy malformation at a single center. This is a referral center for Pediatric Cardiology and for Hepatobiliary and Pancreatic Surgery. The patients presented to the Pulmonary Hypertension Clinic/the Hepatobiliary Surgery Clinic. Out of nine patients, four were male. Type II Abernethy malformation was present in five patients whereas three patients had type I malformation. One of the patients had communication between inferior mesenteric vein and internal iliac vein. Five out of nine patients were erroneously diagnosed as idiopathic primary pulmonary hypertension and were treated with vasodilators. One patient required living donor liver transplant. One patient was managed with surgical shunt closure whereas two patients required transcatheter shunt closure. The rest of the patients were managed conservatively. Abernethy malformation is more common than previously thought and the diagnosis is often missed. There are various management options for Abernethy malformation, which includes surgical or transcatheter shunt closure and liver transplant. Management of Abernethy malformation depends upon type, presentation, and size of shunt.