Abstract: The mineral in human bone is not pure stoichiometric calcium phosphate (Ca/P) as it is partially substituted by in organic elements. In this study, the copper ions (Cu2+) substituted hydroxyapatite (CuHA) powder has been synthesized by the co-precipitation method. The CuHA powder has been used to fabricate CuHA fiber scaffolds by sol-gel process and the following sinter process. The resulted CuHA fibers have slightly different microstructure (i.e. porosity) compared to HA fiber scaffold, which is denser. The mechanical properties test was used to evaluate CuHA, and the results showed decreases in both compression strength and hardness tests. Moreover, the in vitro used endothelial cells to evaluate the angiogenesis of CuHA. The result illustrated that the viability of endothelial cell on CuHA fiber scaffold surfaces tends to antigenic behavior. The results obtained with CuHA scaffold give this material benefit in biological applications such as antimicrobial, antitumor, antigens, compacts, filling cavities of the tooth and for the deposition of metal implants anti-tumor, anti-cancer, bone filler, and scaffold.
Abstract: Diets high in processed foods have been found to lack
essential micro-nutrients for optimum human development and
overall health. Some micro-nutrients such as copper (Cu) have been
found to enhance the inflammatory response through its oxidative
functions, thereby having a role in cardiovascular disease, metabolic
syndrome, diabetes and related complications. This research study
was designed to determine if food crops could be bio-fortified with
micro-nutrients by growing sprouts on mineral fortified fiber mats. In
the feasibility study described in this contribution, recycled cellulose
fibers and clay, saturated with either micro-nutrient copper ions or
copper nanoparticles, were converted to a novel mineral-cellulose
fiber carrier of essential micro-nutrient and of antimicrobial
properties. Seeds of Medicago sativa (alfalfa), purchased from a
commercial, organic supplier were germinated on engineered
cellulose fiber mats. After the appearance of the first leaves, the
sprouts were dehydrated and analyzed for Cu content. Nutrient
analysis showed ~2 increase in Cu of the sprouts grown on the fiber
mats with copper particles, and ~4 increase on mats with ionic copper
as compared to the control samples. This study illustrates the
potential for the use of engineered mats as a viable way to increase
the micro-nutrient composition of locally-grown food crops and the
need for additional research to determine the uptake, nutritional
implications and risks of micro-nutrient bio-fortification.
Abstract: The preparation of Cu nanoparticles (NPs) through the reduction of copper ions by sodium borohydride in the presence of sodium polyacrylate with a molecular weight of 1200 is reported. Cu NPs were synthesized at a concentration of copper salt equal to 2.5, 5, and 10 mM, and at a molar ratio of copper ions and monomeric unit of polyacrylate equal to 1:2. The as-prepared Cu NPs have diameters of about 2.5–3 nm for copper concentrations of 2.5 and 5 mM, and 6 nm for copper concentration of 10 mM. Depending on the copper salt concentration and concentration of additionally added polyacrylate to Cu particle dispersion, primarily formed NPs grow through the process of aggregation and/or coalescence into clusters and/or particles with a diameter between 20–100 nm. The amount of additionally added sodium polyacrylate influences the stability of Cu particles against air oxidation. The catalytic efficiency of the prepared Cu particles for the reduction of 4-nitrophenol is discussed.
Abstract: This paper describes a method for preparing metallic Cu nanoparticles in aqueous solution, and a metal-metal bonding technique using the Cu particles.Preparation of the Cu particle colloid solution was performed in water at room temperature in air using a copper source (0.01 M Cu(NO3)2), a reducing reagent (0.2 - 1.0 M hydrazine), and stabilizers (0.5×10-3 M citric acid and 5.0×10-3 M cetyltrimethylammonium bromide). The metallic Cu nanoparticles with sizes of ca. 60nm were prepared at all the hydrazine concentrations examined. A stage and a plate of metallic Cu were successfully bonded under annealing at 400oC and pressurizing at 1.2 MPa for 5min in H2 gas with help of the metallic Cu particles. A shear strength required for separating the bonded Cu substrates reached the maximum value at a hydrazine concentration of 0.8M, and it decreased beyond the concentration. Consequently, the largest shear strength of 22.9 MPa was achieved at the 0.8 M hydrazine concentration.
Abstract: This paper presents a critical study about the
application of Neural Networks to ion-exchange process. Ionexchange
is a complex non-linear process involving many factors
influencing the ions uptake mechanisms from the pregnant solution.
The following step includes the elution. Published data presents
empirical isotherm equations with definite shortcomings resulting in
unreliable predictions. Although Neural Network simulation
technique encounters a number of disadvantages including its “black
box", and a limited ability to explicitly identify possible causal
relationships, it has the advantage to implicitly handle complex
nonlinear relationships between dependent and independent
variables. In the present paper, the Neural Network model based on
the back-propagation algorithm Levenberg-Marquardt was developed
using a three layer approach with a tangent sigmoid transfer function
(tansig) at hidden layer with 11 neurons and linear transfer function
(purelin) at out layer. The above mentioned approach has been used
to test the effectiveness in simulating ion exchange processes. The
modeling results showed that there is an excellent agreement between
the experimental data and the predicted values of copper ions
removed from aqueous solutions.
Abstract: A new chelating resin is prepared by coupling
Amberlite XAD-4 with 1-amino-2-naphthole through an azo spacer.
The resulting sorbent has been characterized by FT-IR, elemental
analysis and thermogravimetric analysis (TGA) and studied for
preconcentrating of Cu (II) using flame atomic absorption
spectrometry (FAAS) for metal monitoring. The optimum pH value
for sorption of the copper ions was 6.5. The resin was subjected to
evaluation through batch binding of mentioned metal ion.
Quantitative desorption occurs instantaneously with 0.5 M HNO3.
The sorption capacity was found 4.8 mmol.g-1 of resin for Cu (II) in
the aqueous solution. The chelating resin can be reused for 10 cycles
of sorption-desorption without any significant change in sorption
capacity. A recovery of 99% was obtained the metal ions with 0.5 M
HNO3 as eluting agent. The method was applied for metal ions
determination from industrial waste water sample.
Abstract: In this study the adsorption of Cu (II) ions from aqueous solutions on synthetic zeolite NaA was evaluated. The effect of solution temperature and the determination of the kinetic parameters of adsorption of Cu(II) from aqueous solution on zeolite NaA is important in understanding the adsorption mechanism. Variables of the system include adsorption time, temperature (293- 328K), initial solution concentration and pH for the system. The sorption kinetics of the copper ions were found to be strongly dependent on pH (the optimum pH 3-5), solute ion concentration and temperature (293 – 328 K). It was found, the pseudo-second-order model was the best choice among all the kinetic models to describe the adsorption behavior of Cu(II) onto ziolite NaA, suggesting that the adsorption mechanism might be a chemisorptions process The activation energy of adsorption (Ea) was determined as Cu(II) 13.5 kJ mol-1. The low value of Ea shows that Cu(II) adsorption process by zeolite NaA may be an activated chemical adsorption. The thermodynamic parameters (ΔG0, ΔH0, and ΔS0) were also determined from the temperature dependence. The results show that the process of adsorption Cu(II) is spontaneous and endothermic process and rise in temperature favors the adsorption.