A numerical simulation for magnetohydrodynamic nanofluid flow and heat transfer in rotating horizontal annulus with thermal radiation

The impact of an axial magnetic field on the heat transfer and nanofluid flow among two horizontal coaxial tubes in the presence of thermal radiation was considered in this study. The impact of viscous dissipation was also considered. The well-known KKL (Koo–Kleinsteuer–Li) model was applied to approximate the viscosity of the nanofluid and the effective thermal conductivity. Furthermore, proper transformations for the velocity and temperature were applied in this study to obtain a set of ODEs (ordinary differential equations) for basic equations governing the flow, heat and mass transfer. In addition, the 4th order Runge–Kutta (RK) numerical scheme was applied to solve the differential equations along with the associated boundary conditions. The impacts of different parameters, including Hartmann number, Reynolds number, radiation parameter and aspect ratio, on the heat transfer and flow features were studied. According to the results, the value of the Nusselt number increases with an increase in the radiation parameter, Hartmann number and aspect ratio and a decrease in the Reynolds number and Eckert number.

The impact of an axial magnetic field on the heat transfer and nanofluid flow among two horizontal coaxial tubes in the presence of thermal radiation was considered in this study.

Nanofibrous Poly(ε-Caprolactone)/Poly(Vinyl Alcohol)/Chitosan Hybrid Scaffolds for Bone Tissue Engineering using Mesenchymal Stem Cells

In the present study, based on a biomimetic approach, novel 3D nanofibrous hybrid scaffolds consisting of poly(ε-caprolactone), polyvinyl alcohol), and chitosan were developed via a multi-jet electrospinning method. The influence of chemical, physical, and structural properties of the scaffolds on the differentiation of mesenchymal stem cells into osteoblasts, and the proliferation of the differentiated cells were investigated. Osteogenically induced cultures revealed that cells were well-attached, penetrated into the construct and were uniformly distributed. The expression of early and late phenotypic markers of osteoblastic differentiation was upregulated in the constructs cultured in osteogenic medium.

The first ICRANet catalog of binary-driven hypernovae

In a series of recent publications, scientists from ICRANet, led by professor Remo Ruffini, have reached a novel comprehensive picture of gamma-ray bursts (GRBs) thanks to their development of a series of new theoretical approaches. Among those, the induced gravitational collapse (IGC) paradigm explains a class of energetic, long-duration GRBs associated with Ib/c supernovae (SN), recently named binary-driven hypernovae (BdHNe).

BdHNe have a well defined set of observational features which allow to identify them. Among them, the main two are: 1) long duration of the GRB explosion, namely larger than 2 s in the rest frame; 2) a total energy, released in all directions by the GRB explosion, larger than 1052 ergs.

A striking result is the observation, in the BdHNe sources, of a universal late time power-law decay in the X-rays luminosity after 104 s, with typical decaying slope of ~ 1.5. This leads to the possible establishment of a new distance indicator having redshift up to z ~ 8.

Thanks to this novel theoretical and observational understanding, it was possible for ICRANet scientists to build the firstst BdHNe catalog, composed by the 345 BdHNe identified up to the end of 2016.

Evolution of an electron-positron plasma produced by induced gravitational collapse in binary-driven hypernovae

The binary-driven hypernova (BdHN) model has been introduced in the past years, to explain a subfamily of gamma-ray bursts (GRBs) with energies Eiso ≥ 1052 erg associated with type Ic supernovae. Such BdHNe have as progenitor a tight binary system composed of a carbon-oxigen (CO) core and a neutron star undergoing an induced gravitational collapse to a black hole, triggered by the CO core explosion as a supernova (SN). This collapse produces an optically-thick e+e- plasma, which expands and impacts onto the SN ejecta. This process is here considered as a candidate for the production of X-ray flares, which are frequently observed following the prompt emission of GRBs. In this work we follow the evolution of the e+e- plasma as it interacts with the SN ejecta, by solving the equations of relativistic hydrodynamics numerically. Our results are compatible with the Lorentz factors estimated for the sources that produce the flares, of typically Γ ≲ 4.

The binary progenitors of short and long GRBs and their gravitational-wave emission

We have sub-classified short and long-duration gamma-ray bursts (GRBs) into seven families according to the binary nature of their progenitors. Short GRBs are produced in mergers of neutron-star binaries (NS-NS) or neutron star-black hole binaries (NS-BH). Long GRBs are produced via the induced gravitational collapse (IGC) scenario occurring in a tight binary system composed of a carbon-oxygen core (COcore) and a NS companion. The COcore explodes as type Ic supernova (SN) leading to a hypercritical accretion process onto the NS: if the accretion is sufficiently high the NS reaches the critical mass and collapses forming a BH, otherwise a massive NS is formed. Therefore long GRBs can lead either to NS-BH or to NS-NS binaries depending on the entity of the accretion. We discuss for the above compact-object binaries: 1) the role of the NS structure and the nuclear equation of state; 2) the occurrence rates obtained from X and gamma-rays observations; 3) the predicted annual number of detections by the Advanced LIGO interferometer of their gravitational-wave emission.

Isolation of indigenous Glutathione producing Saccharomyces cerevisiae strains

BACKGROUND

Glutathione (GSH) is a non-protein thiol compound, which plays an important role in the response to oxidative stress and nutritional stress. The aim of this study was to isolate indigenous S. cerevisiae strains capable of effectively produce GSH.

METHODS

One hundred-twenty sweet fruit samples were collected. The strains were isolated on yeast glucose chloramphenicol (YGC) agar medium and identified. The isolates were evaluated for GSH producing on yeast malt (YM) medium. Concentration of glutathione was investigated by recording absorbance of all samples at wavelength 412 nm (Ellman's method). In addition, optimization of glucose and peptone concentration in culture medium and the effects of various environmental conditions such as temperature (20-35 °C), agitation rate (150-250 rpm), and initial pH (4.0-6.0) were assessed on producing of GSH.

RESULTS

From 120 samples, 80 isolates were identified by morphological, biochemical and molecular tests as S. cerevisiae. Five isolates were capable to produce effectively GSH. The optimal culture conditions were agitation rate, 200 rpm; temperature, 30 °C; initial pH, 6; glucose, 30 g/l; and peptone concentration, 5 g/l. In optimal conditions, the amount of derived glutathione was improved compared to YM basal medium and highest GSH concentration (296.8 mg/l) was obtained after cultivation with shaking for 72 h.

CONCLUSION

The possibility of obtaining S. cerevisiae cells with a high GSH intracellular content can be considered an interesting opportunity of furthering the range of application and utilization of this molecule.

Effects of Hydroalcoholic Extract of Watercress (Nasturtium Officinale) Leaves on Serum Glucose and Lipid Levels in Diabetic Rats

OBJECTIVE

Hyperlipidemia is a known complication of diabetes mellitus and predisposes to coronary heart disease. The lowering of total cholesterol and low density lipoprotein (LDL)-cholesterol should reduce the incidence of coronary disease. The aim of the present study was to examine the antihyperlipidemic and antidiabetic effects of the hydroalcoholic extract of watercress (Nasturtium officinale) leaves in streptozotocin-induced diabetic rats.

METHODS

Female Wistar rats were randomly divided into 4 groups: control, diabetic and diabetic rats treated with the extract of watercress (Nasturtium officinale) at doses of 100 and 200 mg/kg. Diabetic rats received the watercress extract daily in drinking water for 4 weeks since the day after diabetes confirmation. The levels of serum glucose and lipids were spectrophotometrically measured in all groups at weeks 0 (before diabetes induction), 2 and 4.

RESULTS

There was a significant increase in serum glucose, triglycerides, total cholesterol, and LDL-cholesterol in streptozotocin-induced diabetic rats, accompanied by a decrease in high density lipoprotein (HDL)-cholesterol. The treatment of diabetic rats with hydroalcoholic extract of watercress (Nasturtium officinale) leaves over a 4-week period significantly reduced serum glucose, total cholesterol and LDL- cholesterol in comparison with diabetic untreated rats.

CONCLUSION

Our findings demonstrated that a 4-week treatment with watercress extract at a dose of 200 mg/kg has hypoglycemic and hypolipidemic effects in streptozotocin-diabetic rats. This implies that the consumption of watercress leaves can be helpful in reducing the complications of hyperglycemia and dyslipidemia associated with diabetes.

Antihyperglycemic and antihyperlipidemic effects of hydroalcoholic extract of Securigera securidaca seeds in streptozotocin-induced diabetic rats

Background:

Hyperlipidemia is an associated complication of diabetes mellitus. Lowering of serum lipid levels seems to be associated with a decrease in the risk of vascular disease and related complications. The purpose of the current study was to evaluate the antihyperglycemic and antihyperlipidemic effects of the hydroalcoholic extract of Securigera securidaca seeds in streptozotocin-induced diabetic rats.

Materials and Methods:

Female Wistar rats were randomly divided into four groups as follows: Control, diabetic, and diabetic rats treated with the Securigera extract at doses of 100 and 200 mg/kg. The animals were rendered diabetic by a single intraperitoneal injection of 55 mg/kg streptozotocin. Diabetic rats received the Securigera extract daily in drinking water from the day on which diabetes was confirmed for 4 weeks. The levels of serum glucose and lipids were spectrophotometrically measured in all groups at weeks 0 (before diabetes induction), 2, and 4.

Results:

The results showed that there was a significant increase in serum glucose, triglycerides, total cholesterol, and low density lipoprotein (LDL)-cholesterol in streptozotocin-induced diabetic rats, accompanied by a decrease in high density lipoprotein (HDL)-cholesterol. Treatment of diabetic rats with S. securidaca seed extract at a dose of 200 mg/kg over a 4-week period significantly reduced the levels of serum glucose, total cholesterol, and LDL-cholesterol and increased the level of HDL-cholesterol, compared to diabetic untreated rats.

Conclusions:

Securigera extract at a dose of 200 mg/kg exhibited hypoglycemic and hypolipidemic activities in streptozotocin-diabetic rats during the 4-week treatment period. This provides a valid scientific basis for using it in the treatment of diabetes in Iranian folk medicine.

Synthesis and application of FePt/CNTs nanocomposite as a sensor and novel amide ligand as a mediator for simultaneous determination of glutathione, nicotinamide adenine dinucleotide and tryptophan

In this study, we report the synthesis and application of a FePt/CNTs nanocomposite as a highly sensitive sensor and novel amide ligand (9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)-4-ethylbenzene-1,2-diol as a mediator for the determination of glutathione (GSH), nicotinamide adenine dinucleotide (NADH) and tryptophan (Trp). The synthesized materials were characterized with different methods such as NMR, IR spectroscopy, TEM, XRD, FESEM, cyclic voltammetry, electrochemical impedance spectroscopy and square wave voltammetry (SWV). The modified electrode exhibited a potent and persistent electron mediating behavior followed by well-separated oxidation peaks of GSH, NADH and Trp. The peak currents were linearly dependent on GSH, NADH and Trp concentrations in the range of 0.08-220, 1.0-400 and 5.0-500 μmol L(-1), with detection limits of 0.05, 0.8 and 1.0 μmol L(-1), respectively. The modified electrode was used for the determination of these compounds in real samples.