Simultaneous kinetic spectrophotometric determination of Cu(II), Co(II) and Ni(II) using partial least squares (PLS) regression

A partial least squares (PLS-1) calibration model based on kinetic—spectrophotometric measurement, for the simultaneous determination of Cu(II), Ni(II) and Co(II) ions is described. The method was based on the difference in the rate of the reaction between Co(II), Ni(II) and Cu(II) ions with 1-(2-pyridylazo)2-naphthol in a pH 5.8 buffer solution and in micellar media at 25°C. The absorption kinetic profiles of the solutions were monitored by measuring the absorbance at 570 nm at 2 s intervals during the time range of 0–10 min after initiation of the reaction. The experimental calibration matrix for the partial least squares (PLS-1) model was designed with 30 samples. The cross-validation method was used for selecting the number of factors. The results showed that simultaneous determination could be performed in the range 0.1-2 μg mL⁻¹ for each cation. The proposed method was successfully applied to the simultaneous determination of Cu(II), Ni(II) and Co(II) ions in water and in synthetic alloy samples.      

Experimental and numerical study of swirling subcooled flow boiling of water in a vertical annulus

In this paper, the effect of making swirling flow inside an annulus on the subcooled boiling heat transfer has been studied and discussed both experimentally and numerically. The Eulerian-Eulerian model and control volume technique have been used for numerical modeling of the problem. The experimental results show that the critical heat flux values are enhanced by making swirling flow. The experimental and numerical results also indicate that by making swirling flow inside the annulus, the subcooled boiling heat transfer coefficients are increased. Moreover, the experimental and numerical values of the boiling heat transfer coefficients show good agreement with each other.     

Theoretical investigation of the structural stabilities,elastic properties and band structure characteristics of platinum carbide

Ab initio calculations based on the density functional theory within the full-potential linearized augmented plane wave method were carried out to investigate the structural stabilities of the different crystallographic phases, the pressure-induced phase transition and the electronic properties of the platinum carbide (PtC) compound. The zinc-blende (ZB), rock-salt (RS), cesium chloride (CsCl), wurtzite (WZ), nickel arsenide (NiAs), lead monoxide (PbO) and the tungsten carbide (WC) phases were considered. The exchange and correlation potential was treated by the generalized-gradient approximation using the Perde–Burke–Ernzerhof parameterization. The thermodynamic properties such as variation of the bulk modulus, lattice constant, heat capacity, thermal expansion and Debye temperature versus pressures and temperatures are investigated. The band structure results show the metallic character of the PtC compound in all the considered phases and the present study also shows that the PtC compound crystallizes in the ZB phase at ambient conditions. The theoretical transition pressures from the ZB to RS for the NiAs, PbO and CsCl transformations were also computed.     

Synthesizing UHMWPE Using Ziegler-Natta Catalyst System of MgCl2(ethoxide type)/ TiCl4/tri-isobutylaluminum

Summery: A Ziegler-Natta catalyst of MgCl₂ (ethoxide type)/TiCl₄ has been synthesized. In order to obtain ultra high molecular weight polyethylene (UHMWPE) tri-isobutylaluminum which is less active to chain transfer was used as cocatalyst. Slurry polymerization was carried out for the polymerization of ethylene while, dilute solution viscometry was performed for the viscosity average molecular weight (Mv) measurement. The effect of [Al]/[Ti] molar ratio, temperature, monomer pressure and polymerization time on the Mv and productivity of the catalyst have been investigated. The results showed increasing [Al]/[Ti] ratio in the range of 78–117, decreased the Mv of the obtained polymer from 7.8 × 10⁶ to 3.7 × 10⁶ however, further increase of the ratio, resulted in decreased of by much slower rate up to [Al]/[Ti] = 588. The higher pressure in the range of 1–7 bars showed the higher the Mv of the polymer obtained, while increasing temperature in the range of 50 to 90 °C decreased the Mv from 9.3 × 10⁶ to 3.7 × 10⁶. The Mv rapidly increase with polymerization time in the first 15 minutes of the reaction, this increase was slowly up to the end of the reaction (120 min). Increasing [Al]/[Ti] ratio raised productivity of the catalyst in the range studied. Rising reaction temperature from 50 to 75 °C increased the productivity of the catalyst however, further increase in the temperature up to the 90 °C decreased activity of the catalyst. Monomer pressure in the range 1 to 7 bars yields higher productivity of the catalyst. Also by varying polymerization conditions synthesizing of UHMWPE with Mv in the range of 3 × 10⁶ to 9 × 10⁶ was feasible.     

Microextraction techniques in therapeutic drug monitoring

Therapeutic drug monitoring (TDM), as part of clinical process of medical treatments, is commonly used to maintain 'therapeutic' drug concentrations. TDM is useful to identify the causes of unwanted or unexpected responses, to prevent unnecessary diagnostic testing, to improve clinical outcomes, and even to save lives. The determination of drug concentration in blood samples requires an excellent sample preparation procedure. Recent trends in sample preparation include miniaturization, automation, high-throughput performance, on-line coupling with analytical instruments and low-cost operation through extremely low or no solvent consumption. Microextraction techniques, such as liquid- and solid-phase microextraction, have these advantages over the traditional techniques. This paper reviews the recent developments in microextraction techniques used for drug monitoring in serum, plasma or blood samples.     

Second-order approximation of angle-ply composite laminated thin plate under combined excitations

The influence of the quadratic and cubic terms on non-linear dynamic characteristics of the angle-ply composite laminated rectangular plate with parametric and external excitations is investigated. The method of multiple time scale perturbation is applied to solve the non-linear differential equations describing the system up to and including the second-order approximation. All possible resonance cases are extracted and investigated at this approximation order. Two cases of the sub-harmonic resonances cases (Ω₂ ? 2ω₁ and Ω₂ ? 2ω₂) in the presence of 1:2 internal resonance ω₂ ? 2ω₁ are considered. The stability of the system is investigated using both frequency response equations and phase-plane method. It is quite clear that some of the simultaneous resonance cases are undesirable in the design of such system as they represent some of the worst behavior of the system. Such cases should be avoided as working conditions for the system. Some recommendations regarding the different parameters of the system are reported. Comparison with the available published work is reported.     

Modified incompressible SPH method for simulating free surface problems

An incompressible smoothed particle hydrodynamics (I-SPH) formulation is presented to simulate free surface incompressible fluid problems. The governing equations are mass and momentum conservation that are solved in a Lagrangian form using a two-step fractional method. In the first step, velocity field is computed without enforcing incompressibility. In the second step, a Poisson equation of pressure is used to satisfy incompressibility condition. The source term in the Poisson equation for the pressure is approximated, based on the SPH continuity equation, by an interpolation summation involving the relative velocities between a reference particle and its neighboring particles. A new form of source term for the Poisson equation is proposed and also a modified Poisson equation of pressure is used to satisfy incompressibility condition of free surface particles. By employing these corrections, the stability and accuracy of SPH method are improved. In order to show the ability of SPH method to simulate fluid mechanical problems, this method is used to simulate four test problems such as 2-D dam-break and wave propagation.     

Insight into the Inclusion Complexation of Fluconazole with Sulfonatocalix[4]naphthalene in Aqueous Solution,Solid-State,and Its Antimycotic Activity

The study aims to assess the interaction between fluconazole and sulfonatocalix[4]naphthalene towards enhancing its dissolution performance and antimycotic activity. A solubility study was carried out at different pH conditions, and the results revealed the formation of a 1:1 molar ratio fluconazole-sulfonatocalix[4]naphthalene inclusion complex with an A_L type phase solubility diagrams. The solid powder systems of fluconazole-sulfonatocalix[4]naphthalene were prepared using kneaded and co-evaporation techniques and physical mixtures. DCS, PXRD, TGA-DTG, FT-IR, and in vitro dissolution performance characterize the prepared systems. According to physicochemical characterization, the co-evaporation approach produces an amorphous inclusion complex of the drug inside the cavity of sulfonatocalix[4]naphthalene. The co-evaporate product significantly increased the drug dissolution rate up to 93 ± 1.77% within 10 min, unlike other prepared solid powders. The antimycotic activity showed an increase substantially (p ≤ 0.05, t-test) antimycotic activity of fluconazole co-evaporate mixture with sulfonatocalix[4]naphthalene compared with fluconazole alone against clinical strains of Candida albicans and Candida glabrata. In conclusion, sulfonatocalix[4]naphthalene could be considered an efficient complexing agent for fluconazole to enhance its aqueous solubility, dissolution performance, and antimycotic activity.     

Anti‐proliferative activity of newly synthesized Cd(II), Cu(II), Zn(II),Ni(II), Co(II), VO(II), and Mn(II) complexes of 2‐((4,9‐dimethoxy‐5‐oxo‐5H‐furo[3,2‐g]chromen‐6‐yl)methylene) hydrazinecarbothioamide on three human cancer cells

Thiosemicarbazone ligand, 2‐((4,9‐dimethoxy‐5‐oxo‐5H‐furo[3,2‐g]chromen‐6‐yl)methylene) hydrazinecarbothioamide and its Cd(II), Cu(II), Zn(II), Ni(II), Co(II), VO(II), and Mn(II) complexes have been prepared and characterized by various spectroscopic and analytical techniques. Complexes molar conductance measurements displayed that all complexes (2–8) are non‐electrolyte. With general composition [M(H₃L)(CH₃COO)₂H₂O].nH₂O, where M = Cd(II), Cu(II), Zn(II), Ni(II), Co(II) and Mn(II) while complex (8) has [VO(H₃L)(SO₄)H₂O].2H₂O formula. Based on analytical and spectral measurements, the octahedral or distorted octahedral geometries suggested for complexes. Ligand and complexes anti‐proliferative activities were assessed against three various human tumor cell lines including breast cancer (MCF‐7), liver cancer (HepG2) and lung cancer (A549) using SRB fluorometric assay and cis‐platin as positive control. The anti‐proliferative activity result indicated that the ligand and its complexes have considerable anti‐proliferative activity analogous to that of ordinarily utilized anti‐cancer drug (cis‐platin). They do their anti‐cancer activities by modifying free radical's generation via raising the superoxide dismutase activity and depletion of intracellular reduced glutathione level, catalase, glutathione peroxidase activities, escorted by highly generation of hydrogen peroxide, nitric oxide and other free radicals leading to tumor cells death, as monitoring by decreasing the protein and nucleic acids synthesis.