Self-assembled micelles of well-defined pentaerythritol-centered amphiphilic A4B8 star-block copolymers based on PCL and PEG for hydrophobic drug delivery

Biodegradable star-shaped poly(?-caprolactone) (PCL) with four arms were synthesized by ring-opening polymerization (ROP) from a symmetric pentaerythritol core via the ‘‘core-first’’ strategy. Subsequently, two samples of the amphiphilic A₄B₈ star-block copolymers with symmetrical topologies [4s(PCL-b-2sPEG)] were synthesized by a macromolecular coupling reaction between carboxyl-terminated poly(ethylene glycol) (PEG) and 4-arm star-shaped PCL macromers with eight -OH end groups. The latter was prepared by attaching 3-hydroxy-2-(hydroxymethyl)-2-methylpropanoic acid (HHMPA) to 4sPCL using a simple two-step reaction sequence. The in vitro cytotoxicity test indicated no apparent cytotoxicity. The amphiphilic star-block copolymers are capable of self-assembling into spherical micelles in water at room temperature, and they possess low critical micelle concentrations (CMCs) of 2∼8 mg/L in aqueous solution which was determined by fluorescence spectroscopy using pyrene as a probe. Transmission electron microscopy (TEM) measurement demonstrated that the micelles exhibit a spherical shape with a size range of 30∼50 nm in diameter. In addition, the hydrophobic and anticancer drug, quercetin, is loaded effectively in the polymeric micelles, suggesting that these new materials are appropriate candidates as hydrophobic drug nanocarriers.     

Electrochemical detection and discrimination of single copy gene target DNA in non-amplified genomic DNA

A sensitive, fast and inexpensive method for direct electrochemical detection of target DNA sequences in non-amplified genomic DNA samples is described. Hybridization detection relies on the alteration in guanine oxidation signal following hybridization of the probe with complementary genomic DNA. Initially, the method was tested to detect target DNA on low cycle number PCR amplicons. Having obtained promising detection results from only 5 cycles product, the feasibility of target sequence detection in extracted genomic DNA without PCR amplification, but with the vortex mediated fragmentation of the large genomic DNA into small pieces was examined. Experimental variables affecting the efficiency of sensor were investigated. Detection experiments with various non-complementary genomic DNAs as well as a proper probe, non-specific with respect to all genomic samples confirmed the excellent selectivity of the approach. The sensitivity of the method for analyzing the vortex mediated fragmentized genomic DNA samples is estimated to be approximately of 0.58 ng/μl.     

Rare earth elements leaching from Chadormalu apatite concentrate: Laboratory studies and regression predictions

The extraction of rare earth elements from apatite concentrate of Chadormalu plant of Iran was studied with the dissolution of ore in nitric acid. The parameters of acidity: 60%, solid to liquid ratio: 30%, leaching time: 30 minute, agitation rate: 200 rpm, temperature: 60 °C and particle size (d₈₀): 50 microns were determined as the optimum operational conditions. The recoveries of lanthanum, cerium, neodymium and yttrium were achieved at 74, 59, 72 and 73%, respectively, in the optimized conditions. Multivariable regression was used to predict La, Ce, Nd, Y and total REEs (Y+Nd+Ce+La) leaching recoveries, using experimental data from laboratory studies. It was achieved quite satisfactory correlations of 0.93, 0.98, 0.99, 0.97 and 0.99 for the prediction of Y, Nd, Ce, La and total REEs recoveries, respectively. It was shown that the proposed equations accurately reproduce the effects of operational variables on the different REEs recoveries, and can be used to optimize the REEs leaching plant.     

An investigation on the behavior of stiffened coupled shear walls considering axial force effect

In most of tall buildings, the main contribution of lateral loads is carried by coupled shear walls. In some cases, the necessary stiffness to withstand the lateral load may not be afforded due to low depth of connecting beams. In order to increase the capacity of the coupled shear walls, beams with high stiffness are added to the system at particular levels. Hence, stiffened coupled shear walls (SCSW) will be produced. Such walls are under axial load resulting from their weight, and this axial load affects the behavior of walls because of their excessive height. In this paper, a new method considering the effect of axial force for geometrically nonlinear analysis of the SCSW has been presented. A computer program has been developed in matlab , and numerical examples have been solved to demonstrate the reliability of this method. The results of the examples show the agreement between the present method and the other methods given in the literature. The effects of the various positions and rigidities of the stiffening beam on the internal forces and the lateral deflection of the structure considering axial force effect have also been investigated. Copyright © 2012 John Wiley & Sons, Ltd.     

Application of surrogate artificial intelligent models for real‐time flood routing

Developing a robust flood forecasting and warning system (FFWS) is essential in flood‐prone areas. Hydrodynamic models, which are a major part of such systems, usually suffer from computational instabilities and long runtime problems, which are particularly important in real‐time applications. In this study, two artificial intelligence models, namely artificial neural network (ANN) and adaptive neuro‐fuzzy inference system (ANFIS), were used for flood routing in an FFWS in Madarsoo river basin, Iran. For this purpose, different rainfall patterns were transformed to run‐off hydrographs using the Hydrologic Engineering Center (HEC)‐1 hydrological model and routed along the river using HEC river analysis system RAS hydrodynamic model. Then, the simulated hydrographs with different lag times were used as inputs for training of ANN and ANFIS models to simulate flood hydrograph at the basin outlet. Results showed that the simulations obtained from ANN and ANFIS coincided with the results simulated by the HEC‐RAS, and application of such models is strongly suggested as a backup tool for flood routing in FFWSs.     

A Route Towards Sustainability Through Engineered Polymeric Interfaces

Chemical vapor deposition (CVD) of polymer films represent the marriage of two of the most important technological innovations of the modern age. CVD as a mature technology for growing inorganic thin films is already a workhorse technology of the microfabrication industry and easily scalable from bench to plant. The low cost, mechanical flexibility, and varied functionality offered by polymer thin films make them attractive for both macro and micro scale applications. This review article focuses on two energy and resource efficient CVD polymerization methods, initiated Chemical Vapor Deposition (iCVD) and oxidative Chemical Vapor Deposition (oCVD). These solvent‐free, substrate independent techniques engineer multi‐scale, multi‐functional and conformal polymer thin film surfaces and interfaces for applications that can address the main sustainability challenges faced by the world today.     

Combination of DAC switches and SAR logics in a 720 MS/s low-bit successive approximation ADC

In this paper a 4-bit 720 MHz low-power successive approximation register ADC is simulated in a 0.18 µm digital CMOS process. By using both of the 2-bit/step and time-interleaved techniques, a high sampling frequency is obtained. To simplify the SAR ADC in low-bit applications, the analog switches are eliminated and replaced with inherent digital switches of SAR logics. The power supply, resolution, sampling frequency, SNDR, and power consumption of the proposed SAR ADC are 1.8 V, 4-bit, 720 MHz, 22.1 dB, and 10 mW.     

An Efficient 5‐Input Exclusive‐OR Circuit Based on Carbon Nanotube FETs

The integration of digital circuits has a tight relation with the scaling down of silicon technology. The continuous scaling down of the feature size of CMOS devices enters the nanoscale, which results in such destructive effects as short channel effects. Consequently, efforts to replace silicon technology with efficient substitutes have been made. The carbon nanotube field‐effect transistor (CNTFET) is one of the most promising replacements for this purpose because of its essential characteristics. Various digital CNTFET‐based circuits, such as standard logic cells, have been designed and the results demonstrate improvements in the delay and energy consumption of these circuits. In this paper, a new CNTFET‐based 5‐input XOR gate based on a novel design method is proposed and simulated using the HSPICE tool based on the compact SPICE model for the CNTFET at the 32‐nm technology node. The proposed method leads to improvements in performance and device count compared to the conventional CMOS‐style design.     

High Throughput,Polymeric Aqueous Two‐Phase Printing of Tumor Spheroids

This paper presents a new 3D culture microtechnology for high throughput production of tumor spheroids and validates its utility for screening anti‐cancer drugs. Two immiscible polymeric aqueous solutions are used and a submicroliter drop of the “patterning” phase containing cells is microprinted into a bath of the “immersion” phase. Selecting proper formulations of biphasic systems using a panel of biocompatible polymers results in the formation of a round drop that confines cells to facilitate spontaneous formation of a spheroid without any external stimuli. Adapting this approach to robotic tools enables straightforward generation and maintenance of spheroids of well‐defined size in standard microwell plates and biochemical analysis of spheroids in situ, which is not possible with existing techniques for spheroid culture. To enable high throughput screening, a phase diagram is established to identify minimum cell densities within specific volumes of the patterning drop to result in a single spheroid. Spheroids show normal growth over long‐term incubation and dose‐dependent decrease in cellular viability when treated with drug compounds, but present significant resistance compared to monolayer cultures. The unprecedented ease of implementing this microtechnology and its robust performance will benefit high throughput studies of drug screening against cancer cells with physiologically relevant 3D tumor models.