Tunable self-assembled stereocomplexed-polylactic acid nanoparticles as a drug carrier

In this study, a model hydrophilic drug (porphyrin) was encapsulated within hydrophobic polylactic acid (PLA) nanoparticles (NPs) with different crystallinity and the relevant release behaviors were investigated. The crystalline modification was done using a modified nanoprecipitation method, where homo and stereocomplexed PLA NPs with different average diameters based on varying polymer concentrations and solvent/nonsolvent ratios (S/N) were prepared. Entrapment efficiency and drug release of sterocomplexed-PLA NPs were compared with neat poly(l -lactic acid) (PLLA) NPs. Furthermore, to get the more sustained release, porphyrin-loaded NPs were immobilized within electrospun poly(d ,l -lactide-co-glycolide (PLGA) nanofibers (NFs). Outcomes revealed that solution concentration and solvent/nonsolvent ratio play significant roles in the formation of homo and stereocomplexed NPs. On the other hand, it was found that the formation of stereocrystals did not significantly affect the size and morphology of NPs compared with neat NPs. With regard to the entrapment efficiency and drug content, stereocomplexd-PLA NPs behave relatively the same as neat PLLA NPs while the more sustained release was observed for stereocomplexed NPs. Also, it was observed that electrospinning of PLGA solution loaded by NPs led to the uniform distribution of NPs into PLGA fibers. Encapsulating the drug-loaded NPs into nanofibers decreased the rate of drug release by 50% after 24 h, compared with direct loading of drug into PLGA NFs. We conclude that it is possible to tune the entrapment efficiency and modify the release rate of the drug by giving small changes in the process parameters without altering the physical properties of the original drug substance and polymer.     

Combination of RSM and NSGA-II algorithm for optimization and prediction of thermal conductivity and viscosity of bioglycol/water mixture containing SiO2 nanoparticles

The fluids containing nanoparticles have enhanced thermo-physical characteristics in comparison with conventional fluids without nanoparticles. Thermal conductivity and viscosity are thermo-physical properties that strongly determine heat transfer and momentum. In this study, the response surface method was firstly used to derive an equation for the thermal conductivity and another one for the viscosity of bioglycol/water mixture (20:80) containing silicon dioxide nanoparticles as a function of temperature as well as the volume fraction of silicon dioxide. Then, NSGA-II algorithm was used for the optimization and maximizing thermal conductivity and minimizing the nanofluid viscosity. Different fronts were implemented and 20th iteration number was selected as Pareto front. The highest thermal conductivity (0.576 W/m.K) and the lowest viscosity (0.61 mPa.s) were obtained at temperature on volume concentration of (80 °C and 2%) and (80 °C without nanoparticle) respectively. It was concluded that the optimum thermal conductivity and viscosity of nanofluid could be obtained at maximum temperature (80 °C) or a temperature close to this temperature. An increase in the volume fraction of silicon dioxide led to the enhancement of thermal conductivity but the solution viscosity was also increased. Therefore, the optimum point should be selected based on the system requirement.     

Direct effect of nanoparticles on the thermal conductivity of CuO-water nanofluid in a phase transition phenomenon using molecular dynamics simulation

Journal of Thermal Analysis and Calorimetry - The thermal behavior of CuO-water nanofluid is examined on an aluminum surface. The dimensions of simulation boxes are...     

Preparation of ethylene/α-olefins copolymers using (2-RInd)2ZrCl2/MCM-41 (R:Ph,H) catalyst,microstructural study

(2-RInd)₂ZrCl₂ (R:Ph,H) catalyst was supported on MCM-41 and ethylene copolymerization behavior as well as microstructure of copolymers were studied. A steady rate–time profile behavior was observed for homo and copolymerization of ethylene using supported catalysts. It was noticed that increasing the comonomer content can result in lower physical properties. The obtained results indicated that (2-PhInd)₂ZrCl₂/MCM-41 had higher ability of comonomer incorporation than the non-substituted supported catalysts. The CCC, CCE, and ECC (C: comonomer, E: ethylene) triad sequence distribution in backbone of copolymers were negligible, that means no evidence could be detected for comonomer blocks. The polymer characterization revealed that utilizing 1-octene instead of 1-hexene as the comonomer leads to more heterogeneous distribution of chemical composition. The heterogeneity of the chemical composition distribution and the physical properties were influenced by the type of comonomer and catalyst. (2-PhInd)₂ZrCl₂/MCM-41 produced copolymers containing narrower distribution of lamellae (0.3–1 nm) than the copolymer produce using Ind₂ZrCl₂/MCM-41 (0.3–1.6 nm).     

Propane-1,2,3-triyl tris(hydrogen sulfate): A mild and effcient recyclable catalyst for the synthesis of biscoumarin derivatives in water and solvent-free conditions简

A simple, efficient, and ecofriendly procedure has been developed using propane-l,2,3-triyl tris（hydrogen sulfate） as a catalyst for the synthesis of biscoumarin derivatives in water and solvent-free conditions. The significant features of the present protocol are simplicity, environmentally benign, high yields, no chromatographic separation, and recyclability of the catalyst.     

A numerical study on the effect of static magnetic field on the hemodynamics of magnetic fluid in biological porous media

Journal of Thermal Analysis and Calorimetry - High interstitial fluid pressure in the tumor is among the most important barriers to drug delivery. The use of the static magnetic field is one of the...     

Evaluation of aerodynamic performance enhancement of Risø_B1 airfoil with an optimized cavity by PIV measurement

Journal of Visualization - Airfoils are mostly inefficient in their off-design conditions. In order to improve the aerodynamic performance of airfoils in these conditions, using an optimized cavity...     

Preparation of chemically deposited thin films of CdS/PbS solar cell

The present paper reports the preparation of a solar cell which has a cross-sectional scheme: ITO/CdS/PbS, containing a commercially transparent conductive ITO; chemically deposited n-type CdS (340 nm) and absorbed layer of p-type PbS (1400 nm). The structural and optical properties of the constituent films are presented. X-ray diffraction showed that all of the thin films are polycrystalline. Using scanning electron microscopy, the present study revealed that the films have uniform surface morphology over the substrate. The solar cell was characterized by determining the open circuit voltage, short-circuit current density, and J–V under 40 mW/cm² solar radiation. The efficiency of the solar cells was 1.35%, which is much higher (0.041, 0.5 and 0.1–0.4%) and slightly smaller (1.65%) than some solar cells reported in the literature.     

Comparisons of mixed systems with decreasing failure rate component lifetimes using dispersive order

Because lifetimes of systems are not deterministic, partially, orders are used for comparison purposes which lead us to provide optimal system configurations. This paper deals with a signature‐based dispersive ordering of mixed systems. It is assumed that component lifetimes are independent and identically distributed, and the common distribution has a decreasing failure rate function. Some illustrative examples are also given.