Influence of circumferential annular grooving design of impeller on suspended fluid force of axial flow blood pump

Aiming at insufficient suspension force on the impeller when the hydraulic suspension axial flow blood pump is start at low speed, the impeller suspension stability is poor, and can’t quickly enter the suspended working state. By establishing the mathematical model of the suspension force on the impeller, then the influence of the circumferential groove depth of the impeller on the suspension force is analyzed, and the annular groove depth on the impeller blade in the direction of fluid inlet and outlet was determined as (0.26, 0.02 mm). When the blood pump starts, there is an eccentricity between the impeller and the pump tube, the relationship between the suspension force and the speed of the impeller under different eccentricities is analyzed. Combined with the prototype experiment, the circumferential annular grooving design of the impeller can make the blood pump rotate at about 3500 rpm into the suspension state, when the impeller is at 8000 rpm, the impeller can basically achieve stable suspension at the eccentricity of 0.1 mm in the gravity direction, indicating that the reasonable circumferential annular grooving design of the impeller can effectively improve the suspension hydraulic force of the impeller and improve the stability of the hydraulic suspension axial flow blood pump.

Co-administration of vitamin D3 and Lacticaseibacillus paracasei DG increase 25-hydroxyvitamin D serum levels in mice

Purpose Subclinical vitamin D (vitD) deficiency enhances the predisposition to a myriad of acute and chronic pathologies in many people worldwide. Due to the scarcity of vitD-rich foods, the consumption of supplements or fortified foods can be required to maintain healthy serum levels of 25-hydroxyvitamin D [25(OH)D], and the major circulating form of vitD that is commonly measured in serum to determine the vitD status. Since the vitD absorption seems to resemble that of lipids, improved emulsification in the gut could favor vitD permeation through the enterocyte membrane. Contextually, we hypothesized that a microorganism with cholecalciferol (vitD3)-solubilization properties may potentially result in enhanced serum vitD levels. Methods and results Six probiotic strains were screened for their ability to create a stable suspension of vitD3 in water: Lacticaseibacillus paracasei DG, L. paracasei LPC-S01, L. paracasei Shirota, L. rhamnosus GG, Limosilactobacillus reuteri DSM 17938, and Lactobacillus acidophilus LA5. The DG strain displayed the strongest vitD3 solubilization ability and, consequently, were used in an in vivo trial where a commercial preparation of vitD3 in refined olive oil was administered by gavage to CD-1 mice with or without the concurrent administration of L. paracasei DG. ELISA measurements showed that the DG strain significantly increased the serum levels of 25(OH) D when administered once a day for 1 week in association with the vitD3 supplement. Conclusion This preliminary pre-clinical study suggests that the combined administration of L. paracasei DG with an oil-based cholecalciferol supplement could contribute to the maintenance of the adequate 25(OH) D serum levels in people at risk of vitD deficiency.

Formulation, Physical Characterization and Antioxidant Potential of Silymarin Suspensions and Emulsions

Silymarin, is a therapeutically important flavonoid act as a hepatoprotective agent. However, has a positive effect on metabolism act as a hydrophobic drug but has a very low bioavailability. The aim of the present study was to prepare appropriate formulations of Silymarin in order to enhance its bioavailability. The natural suspending agents like (Xanthan gum, Tragacanth gum, Acacia gum and Iranian gum) were used for the formulation of suspensions, while emulsions were prepared with the combination of surfactant, co-surfactant and oil. The formulations were evaluated for their physical stability, pH, refractive index and conductivity. Among different formulations and suspensions prepared with xanthan gum as a green stabilizing agents were most stable. Emulsions formulated with tween 80 as a surfactant, polyethylene glycol as co-surfactant and olive oil were clear and stable for more than six months. The refractive index, pH and conductivity of the most stable suspension and emulsions were 1.347, 6.9 and 0.18 s/m and 1.43, 6.9, 0.01 s/m respectively. It was concluded that xanthan gum and tween 80 with polyethylene glycol has a good potential to enhance the therapeutic efficiency and stability of silymarin suspension and emulsion.

Radial basis function neural network–based adaptive sliding mode suspension control for maglev yaw system of wind turbines

The maglev yaw system of wind turbines adopts maglev-driving technology instead of traditional gear-driving technology. It has many advantages, such as no lubrication, simple structure, and high reliability. However, the stable suspension control of maglev yaw system is difficult to achieve due to the unknown disturbance caused by crosswind in a practical environment. In this article, an adaptive sliding mode cascade controller based on radial basis function neural network is proposed for the stable suspension control of maglev yaw system. First, the dynamic mathematical model of maglev yaw system is established. Second, an adaptive sliding mode robust controller using radial basis function neural network is designed as the outer loop air gap tracking controller for precise position control, where radial basis function neural network is employed to estimate the unknown parameter containing disturbance. To eliminate the limitation of the traditional exponential approach law based on sign function in the sliding mode control, an exponential reaching law based on hyperbolic tangent function is introduced to guarantee the smooth suspension control of maglev yaw system. Third, an adaptive controller as the inner loop current tracking controller is designed. Finally, the corresponding simulations and analysis are carried out. The simulation results show that the proposed controller can guarantee the suspension stability of maglev yaw system and suppress the disturbance effectively. Compared with the cascade proportional–integral–derivative controller and improved double power reaching law integral sliding mode controller, the proposed controller has a faster dynamic response and stronger robustness in the presence of unknown external disturbance.

Heterogenisation of a Carbonylation Catalyst on Dispersible Microporous Polymer Nanoparticles

<div>The methanol carbonylation catalyst, <i>cis</i>-[Rh(CO)₂I₂]^–, has been heterogenised within a dispersible microporous polymer support bearing cationic functionality. The microporous polymer has a core-shell structure in which the porous and insoluble core (a co-polymer of divinylbenzene and 4-vinylpyridine) is suspended in solution by long hydrophilic poly(ethylene glycol) chains, allowing a stable suspension of the nanoparticles to form. Incorporation of 4-vinylpyridine as a co-monomer allows post-synthetic modification to generate <i>N</i>-methylpyridinium sites for electrostatic attachment of the anionic rhodium(I) complex. The dispersibility of the polymer-supported catalyst material facilitates the use of <i>in</i> <i>situ</i> transmission IR spectroscopy to obtain kinetic data for the oxidative addition of iodomethane to immobilised <i>cis</i>-[Rh(CO)₂I₂]^– (the rate-limiting step of the carbonylation cycle). Remarkably, the oxidative addition proceeds faster than for the homogeneous system (Bu₄N⁺ counter-ion, CH₂Cl₂, 25 °C). The polymer-supported catalyst was found to be active for methanol carbonylation, with a turnover frequency similar to that of the homogeneous analogue under the same conditions (10 bar CO, MeI/MeOH/CHCl₃, 120 °C). The supported catalyst is easily recovered and is shown to maintain comparable activity upon recycling.</div>

Heterogenisation of a Carbonylation Catalyst on Dispersible Microporous Polymer Nanoparticles

<div>The methanol carbonylation catalyst, <i>cis</i>-[Rh(CO)₂I₂]^–, has been heterogenised within a dispersible microporous polymer support bearing cationic functionality. The microporous polymer has a core-shell structure in which the porous and insoluble core (a co-polymer of divinylbenzene and 4-vinylpyridine) is suspended in solution by long hydrophilic poly(ethylene glycol) chains, allowing a stable suspension of the nanoparticles to form. Incorporation of 4-vinylpyridine as a co-monomer allows post-synthetic modification to generate <i>N</i>-methylpyridinium sites for electrostatic attachment of the anionic rhodium(I) complex. The dispersibility of the polymer-supported catalyst material facilitates the use of <i>in</i> <i>situ</i> transmission IR spectroscopy to obtain kinetic data for the oxidative addition of iodomethane to immobilised <i>cis</i>-[Rh(CO)₂I₂]^– (the rate-limiting step of the carbonylation cycle). Remarkably, the oxidative addition proceeds faster than for the homogeneous system (Bu₄N⁺ counter-ion, CH₂Cl₂, 25 °C). The polymer-supported catalyst was found to be active for methanol carbonylation, with a turnover frequency similar to that of the homogeneous analogue under the same conditions (10 bar CO, MeI/MeOH/CHCl₃, 120 °C). The supported catalyst is easily recovered and is shown to maintain comparable activity upon recycling.</div>

Comparative Study of Specific Loss Power and Transverse Relaxivity of Spinel Ferrite Nanoensembles Coated With Chitosan and Polyethylene Glycol

We synthesized spinel ferrite nanoensembles (MnFe2O4, CoFe2O4, and Fe3O4) using the chemical co-precipitation method and characterized their physical, chemical, and magnetic properties by X-ray diffraction (XRD), transmission electron microscopy (TEM), physical properties measurement system (PPMS), Mössbauer spectroscopy, Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS) and Raman spectroscopy. Their relaxation properties and potential for hyperthermia therapy were determined using nuclear magnetic resonance (NMR) and cell viability assay, respectively. XRD and TEM data confirmed that the particle core sizes were 6–9 nm before coating while their sizes increased to 10–14 nm and 14–20 nm after coating with chitosan and polyethylene glycol (PEG), respectively. Mössbauer spectroscopy showed superparamagnetic behavior for MnFe2O4 nanoparticles and ferrimagnetic behavior for the CoFe2O4 and Fe3O4 nanoparticles. A detailed studies of MH loops of all three ferrites before and after coating showed surface functionalization by a large reduction of coercivity and anisotropy. The successful coating was further confirmed by the peak shifts in the FTIR spectra of the particles whereas Raman spectra of coated ferrites also displayed the characteristic absorption patterns and suppression of the ferrite peaks suggesting successful coating. The induced heating profile of the nanoparticles in stable suspension was tested with a radio frequency magnetic field of 76 mT and a frequency of 400 kHz. High mortality (&gt;98%) of 9 L gliosarcoma cancer cells by hyperthermia suggested that these nanoparticles could be used for cancer therapy. Transverse relaxivities (r2) determined by NMR for chitosan-coated MnFe2O4, CoFe2O4, and Fe3O4 nanoparticles were 297 (±22), 353 (±26), and 345 (±13), mM−1S−1, while for PEG-coated nanoparticles are 165 (±22), 146 (±14), and 159 (±07) mM−1S−1, respectively. Overall these spinel ferrite nanoensembles show great promise for cancer theranostics research applications.

Synergistic Behavior of Graphene and Ionic Liquid as Bio-Based Lubricant Additive

The constant utilization of petroleum-based products has prompted concerns about the environment, hence a replacement for these products must be explored. Biolubricants are a suitable replacement for petroleum-based lubricants as they provide better lubricity. Biolubricant performance can be improved by the addition of graphene. However, there are reports that graphene is unable to form a stable suspension for a long period. This study used a graphene-ionic liquid additive combination to stabilize the dispersion in a biolubricant. Graphene and ionic liquid were dispersed into the biolubricant via a magnetic stirrer. The samples were tested using a high frequency reciprocating rig. The cast iron sample was then further observed using various techniques to determine the lubricating mechanism of the lubricant. Different dispersion stability of graphene was observed for different biolubricants, which can be improved with ionic liquids. All ionic liquid samples maintained an absorbance value of three for one month. The utilization of ionic liquid was also able to decrease the frictional performance by 33%. Further study showed that by using the ionic liquid alone, the frictional could only reduce the friction coefficient by 13% and graphene could only reduce the friction by 7%. A smooth worn surface scar can be seen on the graphene-IL sample compared to the prominent corrosive spot on the IL samples and abrasive scars on graphene samples. This indicates synergistic behavior between the two additives. It was found that the ionic liquid does not only improve the dispersion stability, but also plays a role in forming the tribolayer.