Synthesis of amino-cosubstituted polyorganophosphazenes and fabrication of their nanoparticles for anticancer drug delivery

The development of safe drug carriers is cardinal in cancer therapy, which can target the cancer cells and release the loaded drug on-demand without damaging the healthy cells of the body. In our work, we synthesized three different biodegradable polymers, poly[(ethyl aminobezoate) (ethyl glycinato) phosphazenes] (PABGPs), in different mole ratio of side groups. The successful synthesis of these PABGPs was confirmed by ¹H NMR, ³¹P NMR, FT-IR, and gel permeation chromatography. These PABGPs were fabricated into drug (camptothecin, CPT, a hydrophobic anticancer drug) loaded nanoparticles. These drug-loaded nanoparticles showed good drug release behaviors under normal physiological conditions (pH 7.4 and temperature 37°C). These PABGPs-based nanoparticles may find their application as effective drug carriers for cancer therapy.     

Effect of Fe/Zn ratio in composite catalyst for synthesizing polyoxymethylene dimethyl ethers

Polyoxymethylene dimethyl ethers (PODE_n) are extremely effective diesel additives to reduce soot formation during combustion. We introduce a series of Fe-Zn composite solid acid catalysts (SO₄²⁻/xFe₂O₃-yZnO), for the condensation reaction of methanol and paraformaldehyde (PF) with a cheap and feasible route to efficiently synthesize PODE_n. These catalysts were characterized by different characterization techniques, namely BET, XRD, SEM, EDS, FTIR, and NH₃-TPD and the results showed that Fe/Zn molar ratios strongly influenced the physicochemical characteristics of catalysts, thus affecting the methanol conversion and PODE_1-6 and PODE_3-6 selectivity. Accordingly, the methanol conversion was decreased and the selectivity of PODE_3-6 was increased after increasing the Zn molar content. Comparatively, SO₄²⁻/Fe₂O₃-2ZnO exhibited superior catalytic activity among the various investigated catalysts due to the high acid density of strong acid sites. The optimal reaction conditions were observed to be at a 3.0 wt% catalyst loading (catalyst/reactant mass ratio), 2.5 hours ours of reaction time, a reaction temperature of 403 K, and a molar ratio of 3:1 of CH₂O to methanol, achieving a high selectivity of 99.09% PODE_1-6 and 28.23% PODE_3-6 with 55.16% methanol conversion during the reaction.     

Influence of Chemical Reaction on Mass Transport in Yield Stress Exhibiting Flow Regime

Theoretical Foundations of Chemical Engineering - In this study, the simulations for first-order chemical reactions (constructive and destructive) in the flow of the Casson fluid with...     

Heterogeneous Reactor Modeling of an Industrial Multitubular Packed‐Bed Ethylene Oxide Reactor

The one‐dimensional heterogeneous model of an industrial multitubular packed‐bed ethylene oxide (EO) reactor was developed using the equation‐oriented platform Aspen Custom Modeler. Reactor operation was optimized in terms of maximized EO production and selectivity and enhanced safety related to the presence of oxygen in the EO reactor. Good agreement was found between the model results during validation against the available information under identical operating conditions. The model predicts the behavior of the EO reaction and demonstrates the extent of catalyst utilization with product distribution, product yield, by‐product formation, temperature and concentration profiles, over time and along the length of the reactor or catalyst bed. The model sensitivity studies compute the optimum feed flow, oxygen concentration, feed pressure, etc. and suggest the best operational philosophy.     

A Study on the FTIR Spectroscopy of Polylactide Doped with Nano-Aluminium Oxide and Nano-Cupric Oxide

Elucidation of the structure of naturally existing or synthesized substances is an important criterion in the study of materials to predict the application of the substance. In this study, polylactide was doped with nano-aluminium oxide and nano-cupric oxide with 1 and 3 mg of concentration variants. The interaction between the polymer matrix and the nanoparticles has been studied using Fourier transform infrared. Successful doping of the polymer has been observed. Attention has been drawn to check the intermolecular bonding in films having varying thicknesses, films prepared at higher sonication temperatures, and chemical homogeneity of the doped polymer films.     

Multi-photon imaging of amine-functionalized silica nanoparticles

A convenient and simple strategy for preparing water soluble, photoluminescent functionalized silica nanoparticles (M-dots) in the absence of fluorophores or metal doping is demonstrated. These M-dots can be used for bioimaging using one and two-photon microscopy. Because of their high photostability, low toxicity and high biocompatibility compared with Lumidot? CdSe/ZnS quantum dots, functionalized silica particles are superior alternatives for current bioimaging platforms. Moreover, the presence of a free amine group at the surface of the M-dots allows biomolecule conjugation (e.g. with antibodies, proteins) in a single step for converting these photoluminescent SiO(2) nanoparticles into multifunctional efficient vehicles for theragnostics.     

Corrosion protection of commercial steel using stainless steel coatings deposited by Cathodic Arc Plasma Deposition technique

The commercial steel AISI 1010 was coated with AISI 316L steel using Cathodic Arc Plasma Deposition (CAPD) technique. The coatings were deposited in vacuum and in the presence of nitrogen, acetylene and mixture of the two as reactive gases. The coatings were deposited as a function of time while other parameters remained constant. The coatings 0.75 to 1.3 μm thick were adherent and amorphous. The aqueous corrosion properties of the coated samples in 3.5 wt % NaCl solution were studied by Tafel, cyclic and potentiodynamic polarization measurements. The derived corrosion parameters were then compared among the various uncoated and coated samples. The study revealed that the coated samples were more corrosion resistant than the uncoated one. Similarly, the samples coated in the nitrogen + acetylene mixture atmosphere were more corrosion resistant than the samples coated in only nitrogen and acetylene atmospheres. The corrosion parameters were also compared as a function of coating time to ascertain best coating thickness.     

Tolerance design optimization of machine elements using genetic algorithm

An important problem that faces design engineers is how to assign tolerance limits. In practical applications, tolerances are most often assigned as an informal compromise between functionality, quality and manufacturing cost. Frequently, the compromise is obtained iteratively by trial and error. A more scientific approach is often desirable for better performance. In this paper, a genetic algorithm (GA) is used for the design of tolerances of machine elements to obtain the global optimal solution. The objective is to design the optimum tolerances of the individual components to achieve the required assembly tolerance, zero percentage rejection of the components and minimum cost of manufacturing. The proposed procedure using GA is described in this paper for two tolerance design optimization problems: gear train and overrunning clutch assemblies. Results are compared with conventional techniques and the performances are analyzed.     

SAPO-34 supported Pt–Sn-based novel catalyst for propane dehydrogenation to propylene

The Pt–Sn-based catalyst was intensified using SAPO-34 as support for direct propane dehydrogenation to propylene. The catalyst was prepared by sequential impregnation method and characterized by XRF, BET, XRD, NH₃-IR, NH₃-TPD, H₂-TPR, HR-TEM and O₂-pulse coke analysis. NH₃-TPD, IR spectra and XRD results suggested that the doping of metals on SAPO-34 did not affect its acidic strength and structural topology of support, respectively. Propylene selectivity of 94% and total olefins selectivity greater than 97% was achieved using Pt–Sn/SAPO-34. The results were compared with Pt–Sn/ZSM-5 under identical conditions. The possible reasons for improvement were the larger surface area, shape selectivity and particular by suitable acidity of SAPO-34.     

Photoluminescence,FTIR, and electrical characterization of samarium(III) chloride‐doped polyaniline

The synthesized polyaniline (PANI) is doped with different concentrations of Samarium(III) chloride (SmCl₃). The electrical conductivity of doped PANI samples has been measured in the temperature range (300–400K). It has been found that dc conductivity increases with the increase of dopant concentration. Different parameters, based on the conductivity, such as pre‐exponential factor (σ₀) and activation energy (ΔE) have also been calculated. These parameters exhibit information about the nature and suitability of the dopant. Doped samples are characterized by FTIR and photoluminescence studies, which show the interaction of dopant with PANI. Two sharp peaks of different intensities from PL spectra at 388 and 604nm have appeared in doped PANI, which might be due to the effect of SmCl₃. It has been observed that SmCl₃ (dopant) shows noticeable changes in the electrical and spectroscopic properties of doped PANI. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009