The use of biodegradable polymers for the stabilization of copper nanoparticles synthesized by chemical reduction method

Copper nanoparticles were synthesized by a convenient and rapid chemical reduction method in ambient condition using \(\hbox {Cu}(\hbox {NO}_{3})_{2}{\cdot } 3\hbox {H}_{2}\hbox {O}\) as a precursor, hydrazine hydrate as reducing agent and deionized water as solvent. The product was characterized by X-ray diffraction (XRD) patterns, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and UV–Vis spectroscopy. However, agglomerated copper nanoparticles were obtained by this chemical reduction method. Hence, the effects of three polymers of polyvinyl pyrrolidone, polyethylene glycol (PEG) and starch as stabilizers on the size and size distribution of Cu nanoparticles were investigated. According to the results, smallest copper nanoparticles (30–50 nm) with a narrow size distribution were obtained using PEG as the stabilizing polymer. Zero-valent copper nanoparticles with high purity were obtained by this method and there was no peak related to the oxidized impurities such as CuO and \(\hbox {Cu}_{2}\hbox {O}\) in the XRD and UV–Vis studies, both in the presence and in the absence of stabilizer. On the other hand, by this method, zero-valent copper nanoparticles were obtained in the absence of any anti-oxidant agent and any inert gas flow. The effects of synthesis parameters including initial concentration of precursor, polymer concentration and the reaction temperature on the size and size distribution of copper nanoparticles were investigated using the UV–Vis analysis to determine the optimum synthesis conditions.     

A Radial Flow Microfluidic Device for Ultra‐High‐Throughput Affinity‐Based Isolation of Circulating Tumor Cells

Circulating tumor cells (CTCs) are believed to play an important role in metastasis, a process responsible for the majority of cancer‐related deaths. But their rarity in the bloodstream makes microfluidic isolation complex and time‐consuming. Additionally the low processing speeds can be a hindrance to obtaining higher yields of CTCs, limiting their potential use as biomarkers for early diagnosis. Here, a high throughput microfluidic technology, the OncoBean Chip, is reported. It employs radial flow that introduces a varying shear profile across the device, enabling efficient cell capture by affinity at high flow rates. The recovery from whole blood is validated with cancer cell lines H1650 and MCF7, achieving a mean efficiency >80% at a throughput of 10 mL h^?1 in contrast to a flow rate of 1 mL h^?1 standardly reported with other microfluidic devices. Cells are recovered with a viability rate of 93% at these high speeds, increasing the ability to use captured CTCs for downstream analysis. Broad clinical application is demonstrated using comparable flow rates from blood specimens obtained from breast, pancreatic, and lung cancer patients. Comparable CTC numbers are recovered in all the samples at the two flow rates, demonstrating the ability of the technology to perform at high throughputs.     

Characterization of Cold Spray Titanium Supersonic Jet

Titanium is widely used in aerospace, highly corrosive environments, and implants due to unique properties such as high strength to weight ratio and excellent corrosion resistance. Cold gas dynamic spray (cold spray) technology, in contrast to current fabrication technologies, has provided the potential for titanium to be utilized in broader industrial applications and at lower cost. Particle velocity is the most important parameter in the cold spray process that leads to successful deposition of titanium at supersonic speeds. In this study, particle image velocimetry (PIV) is utilized to characterize supersonic flow field for a commercially pure (CP) titanium powder. The results represent experimentally determined velocity for titanium particles under supersonic conditions with respect to propellant gas, spray temperature, and stagnation pressure. The high velocity flow region outside of the cold spray nozzle was significantly extended using helium. An increase in stagnation temperature results in a high velocity region close to the axis of the cold spray nozzle. In contrast, an increase in pressure expands the high velocity regions in the cold spray plume. The PIV that is a whole-flow-field process is a practical characterization technique for optimization of parameters and validation of the future models for the cold spray process.     

Modeling the Rheological Behavior of Chemically Interesterified Blends of Palm Stearin/Canola Oil as a Function of Physicochemical Properties

The main aim of the current study was to model the rheological and textural properties of chemically interesterified palm stearin (PS)/canola oil (CO) blends as a function of saturated fatty acids (SFA), solid fat content (SFC), and temperature. The results and proposed models in this study can be used in design and development of new fat products by trying to limit the need for instrumental methods. To describe and predict how the viscoelastic properties and firmness of the blends change with SFA content, several models have been proposed. The firmness curves of fat samples were described as a function of (SFA, Firmness _f(SFA), Rsqr = 0.94, and mean absolute error (MAE) = 1009.00 g) and (SFC₂₀, Firmness _f(SFC20), Rsqr = 0.98, and MAE = 750.80 g) using a one-variable Quadratic model. In the next step, a two-variable Quadratic function for expression of firmness as a function of both SFA content and SFC₂₀ with high goodness of fit and low error (Rsqr = 1.00 and MAE = 0.00) was developed. The G′ modulus as a function of temperature (G′ _f(T)) and SFC (G' _f(SFC)) curves was S-shaped and the three Sigmoidal functions (Logistic, Gompertz, and Sigmoid models) were well able to describe their properties. However, the Logistic models described the G′ _f(T) (Rsqr>0.99 and MAE < 7838.00 Pa) and G′ _f(SFC) (Rsqr>0.94 and MAE < 20,802.00 Pa) curves in the best way. Finally, a two-variable Logistic model considering both temperature and SFC as variables was developed and fitted on the experimental data with Rsqr of 0.97 and MAE of 85,367.56 Pa. The validation of the proposed models shows their efficiency and ability for prediction of rheological and textural values of various interestrified blends.     

The study of laminar convective heat transfer of CuO/water nanofluid through an equilateral triangular duct at constant wall heat flux

The present paper focuses on the heat transfer of an equilateral triangular duct by employing the CuO/water nanofluid in a laminar flow and under constant heat flux condition. The triangular ducts were used due to their ease of creation and high compaction. They have less pressure drop when compared to the circular and non‐circular ducts and their other attributes are very useful in industrial applications. These reasons cause their heat transfer characteristics to be very important. In this paper, to improve the heat transfer of an equilateral triangular duct, a CuO/water nanofluid was employed. The nanofluid was conducted through an equilateral triangular duct with a constant wall heat flux. Results show that the experimental heat transfer coefficient of the CuO/water nanofluid is more than that of distilled water. Also, the experimental heat transfer coefficient of a CuO/water nanofluid is greater than the theoretical one. The heat transfer enhancement of the equilateral triangular duct increases with the nanofluid volume concentration as well as the Peclet number. So a 41% enhancement in the convective heat transfer coefficient for a 0.8% CuO/water nanofluid can be seen when compared to pure water. © 2012 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21011     

Correlations of SPT,CPT and pressuremeter test data in alluvial soils. Case study: Tabriz Metro Line 2, Iran

Bulletin of Engineering Geology and the Environment - The Menard pressuremeter modulus (Em), limit pressure (PL), shear modulus (G) and subgrade reaction modulus (Ks) can be obtained by using the...     

Recent Progress on Biodegradable Tissue Engineering Scaffolds Prepared by Thermally-Induced Phase Separation (TIPS)

Porous biodegradable scaffolds provide a physical substrate for cells allowing them to attach, proliferate and guide the formation of new tissues. A variety of techniques have been developed to fabricate tissue engineering (TE) scaffolds, among them the most relevant is the thermally-induced phase separation (TIPS). This technique has been widely used in recent years to fabricate three-dimensional (3D) TE scaffolds. Low production cost, simple experimental procedure and easy processability together with the capability to produce highly porous scaffolds with controllable architecture justify the popularity of TIPS. This paper provides a general overview of the TIPS methodology applied for the preparation of 3D porous TE scaffolds. The recent advances in the fabrication of porous scaffolds through this technique, in terms of technology and material selection, have been reviewed. In addition, how properties can be effectively modified to serve as ideal substrates for specific target cells has been specifically addressed. Additionally, examples are offered with respect to changes of TIPS procedure parameters, the combination of TIPS with other techniques and innovations in polymer or filler selection.     

Removal of malachite green (a toxic dye) from water by cobalt ferrite silica magnetic nanocomposite: Herbal and green sol-gel autocombustion synthesis

Cobalt ferrite-silica nanocomposites were synthesized in the presence of various amounts of Salix alba bark extract via the self-propagating sol-gel process. The structure, morphology and magnetic property of nanostructures was investigated and the adsorbent ability for the removal of malachite green (MG) dye from water through CoFe₂O₄SiO₂ has been reported. The products were characterized by XRD, SEM, TEM, FTIR and VSM techniques. The samples that were synthesized in the presence of more extract (20 mg extract) revealed no trace of impurity in XRD pattern and indicated more spherical and agglomerated particles on SEM images; in contrast other samples indicated Co₃O₄ as impurity besides rough and irregular spherical shapes. TEM images for sample SA20 (15.41 ± 0.65 nm size) illustrated narrow size distribution which is consistent with the SEM analysis. The saturation magnetization values continuously increase with the increasing Salix alba bark extract amount and reaches to 2.89 emu/g for SA20 sample. Investigation on MG adsorption isotherm and kinetic onto the nanocomposites were carried out as well. The experimental data best fitted to the Langmuir model and revealed a monolayer adsorption capacity of 75.5 ± 1.21 mg g^?1. The adsorption kinetic was found to follow pseudo-second-order kinetic model. Consequently, prepared nanocomposite can be used as an effective magnetic adsorbent for the MG removal from water.