PN sequence blind estimation in multiuser DS‐CDMA systems with multipath channels based on successive subspace scheme

In this paper, we proposed a new method based on expanding subspace algorithm and finite alphabet characteristics, for blind estimation of the users' spreading sequences in the multiuser direct sequence code division multiple access system in the presence of the multipath channels. In the proposed scheme, we show that the estimation of the users' overall channels in the direct sequence code division multiple access system is equivalent to the impulse response estimation of the multi‐input multi‐output finite impulse response channels. Our proposed approach is based on the successive estimation of the columns of the equivalent multi‐input multi‐output finite impulse response channels from the lowest degree columns to the highest degree ones. Accordingly, each user's overall channel that is the convolution of the original multipath channel and the spreading sequence is estimated. Then we extract PN sequences from the overall channel using finite alphabet characteristics of the spreading sequence chips for each user. According to simulation results, our proposed scheme outperforms the conventional methods in that it does not require symbol synchronization and does not have channel constraints (for example, AWGN and single user system) in the multipath channels.     

One-step Synthesis of 3,4-Dihydrobenzimidazo[2,1-<Emphasis Type="Italic">b</Emphasis>]quinazolin-1(2<Emphasis Type="Italic">H</Emphasis>)-ones in an Ionic Liquid

Summary.  A novel class of 3,4-dihydrobenzimidazo[2,1-b]quinazolin-1(2H)-ones was synthesized in very short reaction times with good yields in the presence of 3-butyl-1-methyl imidazolium bromide as a room temperature ionic liquid at 120°C. The ionic liquid can be recycled for subsequent reactions without any loss of efficiency.     

Automated analysis of individual particles using a commercial capillary electrophoresis system

Capillary electrophoretic analysis of individual submicrometer size particles has been previously done using custom-built instruments. Despite that these instruments provide an excellent signal-to-noise ratio for individual particle detection, they are not capable of performing automated analyses of particles. Here we report the use of a commercial Beckman P/ACE MDQ capillary electrophoresis (CE) instrument with on-column laser-induced fluorescence (LIF) detection for the automated analysis of individual particles. The CE instrument was modified with an external I/O board that allowed for faster data acquisition rates (e.g. 100 Hz) than those available with the standard instrument settings (e.g. 4 Hz). A series of eight hydrodynamic injections expected to contain 32 +/- 6 particles, each followed by an electrophoretic separation at -300 V cm(-1) with data acquired at 100 Hz, showed 28 +/- 5 peaks corresponding to 31.9 particles as predicted by the statistical overlap theory. In contrast, a similar series of hydrodynamic injections followed by data acquisition at 4 Hz revealed only 8 +/- 3 peaks suggesting that the modified system is needed for individual particle analysis. Comparison of electropherograms obtained at both data acquisition rates also indicate: (i) similar migration time ranges; (ii) lower variation in the fluorescence intensity of individual peaks for 100 Hz; and (iii) a better signal-to-noise ratio for 4 Hz raw data. S/N improved for 100 Hz when data were smoothed with a binomial filter but did not reach the S/N values previously reported for post-column LIF detection. The proof-of-principle of automated analysis of individual particles using a commercially available CE system described here opens exciting possibilities for those interested in the study and analyses of organelles, liposomes, and nanoparticles.     

Dissipative Particle Dynamics Study of Interfacial Properties and the Effects of Nonionic Surfactants on Hydrocarbon/Water Microemulsions

The aim of this work was to apply dissipative particle dynamics (DPD) mesoscopic simulations to study the interfacial orientation and the effect of the nonionic surfactant, hexaethylene glycol monododecyl ether (C₁₂E₆), on different (oil (dodecane)/water) microemulsion systems. The Hildebrand-solubility-parameter model and Flory–Huggins/Hansen-solubility-parameter (FH/HSP) model were combined to evaluate the DPD interaction parameter (a_ij) where the solubility parameters (δ_i) as DPD input parameters were preliminary validated by all-atom molecular dynamics (MD) results and experimental data. The interfacial property dependence of dodecane/water/C₁₂E₆ system on the oil/water (o/w) ratio and on the concentration of surfactant and orientation at the interface were investigated. It was found that the surfactant addition reduced the IFT of o/w interfaces and this reduction was more efficient for water-in-oil microemulsions (o/w ≤ 1).     

Thermodynamic Studies of Insulin Loading into a Glucose Responsive Hydrogel Based on Chitosan‐polyacrylamide‐polyethylene Glycol

The insulin therapy constitutes the preferred treatment for Diabetes Mellitus (DM). The traditional insulin therapy, which consists of daily subcutaneous insulin injections to control blood glucose level, is not able to regulate the blood glucose level precisely. In this research, to facilitate the diabetic patient life, an intelligent drug delivery system based on a biodegrable biopolymer to control the insulin release, was designed. In this system, chitosan‐polyethylene glycol hydrogel and glucose oxidize play the role of drug carrier and glucose biosensor, respectively. To increase the hydrogel drug loading capacity, hydrogels with different PEG content were synthesized and insulin was loaded by swelling‐diffusion method into them. The loaded hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), High performance liquid chromatography (HPLC), and Thermogravimetric analysis (TGA). Finally, the thermodynamic study for insulin loading process was performed to investigate the stability of the drug in the system.     

Hydroarylation of cinnamic acid with phenols catalyzed by acidic ionic liquid [H-NMP]HSO<Subscript>4</Subscript>: computational assessment on substituent effect

Hydroarylation of cinnamic acid with different substituted phenols, in the presence of acidic ionic liquid, N-methyl-2-pyrrolidonum hydrosulfate ([H-NMP]HSO₄) gave the corresponding dihydrocoumarins in high yields and excellent selectivity. Among these substituted phenols, while methyl phenol afforded the corresponding dihydrocoumarin, nitrophenol under the same reaction conditions diverted the course of reaction, affording 3-(4-nitrophenyl)-3-phenylpropanoic acids. We investigated this behavior from the energetic and electronic points of view, using quantum chemistry computational methods. In this respect, the electronic energy change values for the conversion reaction of substituted phenyl cinnamate esters to dihydrocoumarin compounds have been obtained via density functional theory calculations. We demonstrated that the conversion reaction in the presence of CH₃ substituent is more favorable energetically than NO₂ substituent. Moreover, we have concentrated on topological analysis of electron density on some key bond and ring critical points and their associated bond paths to assess the conversion of substituted phenyl cinnamate esters to dihydrocoumarins. Our calculated results showed that para-methyl phenyl cinnamate has more of electronic tendency to undergo the intramolecular cyclization step and, consequently, generate the corresponding dihydrocoumarin.     

Multicomponent synthesis of C-tethered bispyrazol-5-ols using CeO2 nanoparticles as an efficient and green catalyst

Research on Chemical Intermediates - CeO2 nanoparticles have been used as an efficient catalyst for the preparation of C-tethered bispyrazol-5-ols by pseudo five-component reaction of...