Spectral Investigations of Preferential Solvation and Solute–Solvent Interactions of Free Base and Protonated 5,10,15,20-Tetrakis(4-trimethyl-ammonio-phenyl)-porphine Tetratosylate in Aqueous Organic Mixed Solvents

The solvatochromic properties of the free base and the protonated 5,10,15,20-tetrakis(4-trimethyl-ammonio-phenyl)-porphine tetratosylate (TTMAPP) were studied in pure water, methanol, ethanol, 2-propanol, and their corresponding aqueous mixtures. The correlation of the empirical solvent polarity scale (E _T) values of TTMAPP with composition of the solvents were analyzed by the solvent exchange model of Bosch and Roses to clarify the preferential solvation of the probe dyes in the binary mixed solvents. The solvation shell composition effects in preferential solvation of the solute dyes were investigated in terms of both solvent–solvent and solute–solvent interactions and also the local mole fraction of each solvent composition was calculated in the cybotactic region of the probe. The effective mole fraction variation may provide significant physicochemical insights in the microscopic and molecular level of interactions between TTMAPP species and the solvent components and, therefore, can be used to interpret the solvent effect on kinetics and thermodynamics of TTMAPP.     

Uranium recovery from UCF liquid waste by nanoporous MCM-41: breakthrough capacity and elution behavior studies

Adsorption and recovery of uranium by nanoporous MCM-41 from aqueous solutions (synthetic solution and uranium conversion facility liquid waste) were investigated by use of a fixed-bed column (1.2 cm diameter and 3.0 cm height). Adsorption was carried out at flow rates 0.2 and 0.5 mL min^?1, which correspond to retention times of 10 and 6 min. The maximum breakthrough capacity for uranium ions was achieved by use of nanoporous MCM-41 at the optimum pH of 3.6 and flow rate 0.2 mL min^?1 (61.95 μg g^?1). The Thomas and Yan models were applied to the experimental data, by use of linear regression, to determine the characteristics of the column for process design. The breakthrough curves calculated from the models were in good agreement with the experimental data. The elution behavior of uranium on nanoporous MCM-41 was studied with different eluents; the results showed that 0.1 M HCl is good eluent for uranium recovery. The regenerated column could be used in a multitude of adsorption–desorption cycles.     

BSA optimization and dosimetric assessment for an electron linac based BNCT of deep‐seated brain tumors

A study was conducted to investigate a photoneutron spectrum based on a 25 MeV electron linac for treatment of deep-seated brain tumors in the context of boron neutron capture therapy (BNCT). Based on a series of Mont Carlo N-Particle simulations, tungsten and uranium with optimized geometry were selected as the most appropriate converters for (e,γ) and (γ,n) reactions, respectively. The final optimized photoneutron source yield was 5.78 × 10¹³ n/s/mA, which is a high value for these kinds of sources. A beam shaping assembly (BSA) for the proposed neutron source containing optimal moderators, filter, reflector, and collimator was simulated. Results showed that using this BSA enables us to meet International atomic energy agency recommended figures of merit at the BSA beam port. Also, the calculated in-phantom figures of merit and dose evaluation results via a simulated head phantom confirmed that the designed neutron source and its related BSA configuration can potentially treat deep-seated brain tumors in BNCT framework. In the present study, some in-phantom figures of merit such as advantage depth, advantage depth dose rate, advantage ratio, and treatment time are 7.6 cm, 0.7 Gy/min, 4.2, and 17.8 min, respectively.     

Synthesis,crystal structure,and electrochemical properties of Ni(II) and Cu(II) complexes with two unsymmetrical N2O2 Schiff base ligands

Nickel(II) and copper(II) complexes of two unsymmetrical tetradentate Schiff base ligands [Ni(Me-salabza)] (1), [Cu(Me-salabza)] (2) and [Ni(salabza)] (3), {H₂salabza = N,N′-bis[(salicylidene)-2-aminobenzylamine] and H₂Me-salabza = N,N′-bis[(methylsalicylidene)-2-aminobenzylamine]}, have been synthesized and characterized by elemental analysis and spectroscopic methods. The crystal structures of 2 and 3 complexes have been determined by single crystal X-ray diffraction. Both copper(II) and nickel(II) ions adopt a distorted square planar geometry in [Cu(Me-salabza)] and [Ni(salabza)] complexes. The cyclic voltammetric studies of these complexes in dichloromethane indicate the electronic effects of the methyl groups on redox potential.     

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.     

An approach to the synthesis and characterization of HMS/Pr-Rh-Zr as efficient catalyst for synthesis of tetrahydrobenzo[b]pyran and 1,4-dihydropyrano[2,3-c]pyrazole derivatives

Research on Chemical Intermediates - The aim of present investigation is the synthesis of mesoporous catalyst based on hexagonal mesoporous silica. HMS support has exceptional properties such as...     

Synthesis and Characterization of H3PW12O40 and H3PMo12O40 Nanoparticles by a Simple Method

In this study H₃PW₁₂O₄₀·9H₂O and H₃PMo₁₂O₄₀·6H₂O (HPA) particles were changed into nano forms by heat-treatment in an autoclave as a simple, repaid, inexpensive and one step method. The particle size of these nanoparticles was around 25 nm. The as-synthesized nanostructures were characterized by dynamic light scattering, X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy and inductively coupled plasma analyzer. Thermal stability of nanoparticles was surveyed by thermal gravimeter analyse. Acidity of prepared nanoparticles was investigated by pyridine adsorption method. Results showed rising acidity by declining particle size of HPA.     

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.     

Controllable one-step synthesis of ZnO nanostructures using molybdophosphoric acid

ZnO nanostructures were synthesised in a hydrothermal reaction of zinc acetate in the presence of molybdophosphoric acid (H₃[PMo₁₂O₄₀]) as well as its vanadium-substituted acid (H₄[PMo₁₁VO₄₀]) at various times, temperatures, and concentrations. The ZnO nanostructures were characterised by X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. The results demonstrated that the synthesised products are crystalline with a zincite hexagonal phase. Various ZnO nanostructures, such as nanoparticles, microrods, and nanosheets, were produced by changing the experimental conditions. The photocatalytic degradation of methyl orange was also investigated using the ZnO nanoparticles thus prepared. These particles exhibited high performance in the photocatalytic degradation of MO and almost 100 % decolourisation occurred within only 20 min.