Synthesis of 2‐Oxopyridine‐Fused 1,3‐Diazaheterocyclic Compounds via a Three‐Component Reaction

An efficient and simple route for the preparation of 2‐oxopyridine‐fused 1,3‐diazaheterocyclic compounds via a three component reaction is described. It involves the reaction between alkylenediamines 1 , 1,1‐bis(methylsulfanyl)‐2‐nitroethene, and alkyl prop‐2‐ynoates 2 in refluxing THF (Table). The structures were corroborated by spectroscopic (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and elemental analyses. A plausible mechanism for this type of cyclization is proposed (Scheme).     

A novel and efficient solvent-free and heterogeneous method for the synthesis of primary, secondary and bis-N-acylsulfonamides using metal hydrogen sulfate catalysts

Some metal hydrogen sulfates were used as acid catalysts in the N-acylation of different sulfonamides using carboxylic acid chlorides and anhydrides as acylating agents under both heterogeneous and solvent-free conditions. Al(HSO₄)₃ and Zr(HSO₄)₄ were found to have the highest activity and catalyze the reactions efficiently to furnish the primary N-acyl sulfonamides (RCONHSO₂R′), secondary N-acylsulfonamides (RCONR″SO₂R′) and bis-N-acylsulfonamnides [RCO(SO₂R′)N-R″-N(SO₂R′)COR] in good to high yield. The mild reaction conditions, inexpensive and low toxicity of catalysts and easy work-up procedure make this method attractive.     

Numerical Investigation of Drug Delivery to Cancerous Solid Tumors by Magnetic Nanoparticles Using External Magnet

Chemotherapy as one of the most utilized cancerous tumor treatment methods introduces undesired side effects due to penetrating toxic drugs into the healthy organs. Delivery of anticancer therapeutic agents to solid tumors is also problematic. The purpose of current study is to investigate the penetration of magnetic drug carriers (MDCs) within the cancerous solid tumor tissue under the influence of external magnet. Capillary wall and tumor tissue is modeled as a saturated porous media. In order to solve the coupled governing equations, mass, momentum and concentration, an in-house finite volume-based code is developed and utilized. Results show the penetration of MDCs into the tumor in the absence of magnetic field is minimal and is limited to the surface of the tumor. On the other hand, under the influence of external magnet the penetration of MDCs within the tumor increases exponentially. They also penetrate deep into the tumor and cover the entire tumor which increase the effectivity and decrease the side effect of the treatment.     

Identifying the Interfacial Polarization in Non-stoichiometric Lead-Free Perovskites by Defect Engineering

Recent advances in perovskite ferroelectrics have fostered a host of exciting sensors and actuators. Defect engineering provides critical control of the performance of ferroelectric materials, especially lead-free ones. However, it remains a challenge to quantitatively study the concentration of defects due to the complexity of measurement techniques. Here, a feasible approach to analyzing the A-site defect and electron in alkali metal niobate is demonstrated. The theoretical relationships among defect concentration, conductivity, and oxygen partial pressure can be established based on the defect chemistry equilibria. The type and concentration of defects are reflected through the conductivity variation with oxygen partial pressure. As a result, the variation of defect concentration gives rise to defect-driven interfacial polarization, which further leads to distinct properties of the ceramics. e.g., abnormal dielectric behavior. Furthermore, this study also suggests a strategy to manipulate defects and charges in perovskite oxides for performance optimization.     

Synthesis and Characterization of Tricarbastannatranes and Their Reactivity in B(C6F5)3‐Promoted Conjugate Additions

The synthesis and characterization of a series of tricarbastannatranes, in the solid state and in solution, are described. The structures of the complexes [N(CH₂CH₂CH₂)₃Sn](BF₄), [N(CH₂CH₂CH₂)₃Sn](SbF₆), [N(CH₂CH₂CH₂)₃Sn]₄[(SbF₆)₃Cl], and [(N(CH₂CH₂CH₂)₃Sn)₂OH][MeB(C₆F₅)₃] were determined by X‐ray crystallography. Furthermore, the B(C₆F₅)₃‐promoted conjugate addition of alkyl‐tricarbastannatranes to benzylidene derivatives of Meldrum’s acid was investigated, and detailed mechanistic studies are presented.     

Effects of Sucrose and Trehalose on Stability,Kinetic Properties,and Thermal Aggregation of Firefly Luciferase

In this study, we used sugars as stabilizing additives to improve the thermostability and to inhibit aggregation of firefly luciferase. The combination of sucrose and trehalose has a strong stabilizing effect on firefly luciferase activity and prevents its thermoinactivation. These additives can also increase optimum temperature. It has been shown that the presence of both sucrose and trehalose can inhibit thermal aggregation of firefly luciferase and decrease bioluminescence decay rate. In order to understand the molecular mechanism of thermostabilization, we investigated the effects of sucrose and trehalose combination on the secondary structure of luciferase by Fourier transform infrared spectroscopy. Minor changes in content of secondary structure of firefly luciferase are observed upon treatment with additives.     

Investigation of intermolecular interactions in perylene films on Au(111) by infrared spectroscopy

Intermolecular interactions in crystalline perylene films on Au(111) have been investigated by Fourier transform infrared spectroscopy. Dimer modes of vibrations are observed in the crystalline film, in contrast to the monomer modes found for isolated perylene molecules. These dimers are formed via hydrogen bonding in the sandwich herringbone structure of the crystalline α-phase. Davydov splitting of both the monomer and the dimer modes is observed due to resonance dynamic intermolecular interaction. The splitting of monomer modes into three distinct vibrations and the occurrence of the dimer modes confirm that the film crystallizes in the α phase, which is in line with the x-ray diffraction results. The frequency shift and band broadening at elevated temperature have been attributed to the cubic and quartic anharmonic interactions.     

Optimization and characterization of liposome formulation by mixture design

This study presents the application of the mixture design technique to develop an optimal liposome formulation by using the different lipids in type and percentage (DOPC, POPC and DPPC) in liposome composition. Ten lipid mixtures were generated by the simplex-centroid design technique and liposomes were prepared by the extrusion method. Liposomes were characterized with respect to size, phase transition temperature, ζ-potential, lamellarity, fluidity and efficiency in loading calcein. The results were then applied to estimate the coefficients of mixture design model and to find the optimal lipid composition with improved entrapment efficiency, size, transition temperature, fluidity and ζ-potential of liposomes. The response optimization of experiments was the liposome formulation with DOPC: 46%, POPC: 12% and DPPC: 42%. The optimal liposome formulation had an average diameter of 127.5 nm, a phase-transition temperature of 11.43 °C, a ζ-potential of -7.24 mV, fluidity (1/P)(TMA-DPH)((?)) value of 2.87 and an encapsulation efficiency of 20.24%. The experimental results of characterization of optimal liposome formulation were in good agreement with those predicted by the mixture design technique.