Mathematical modeling for facilitated transport of Ge(IV) through supported liquid membrane containing Alamine 336

A mathematical model was developed for the germanium-facilitated transport from a medium containing tartaric acid using Alamine 336 as a carrier. Modeling was carried out based on the extraction constant (K _ext) obtained from the liquid–liquid extraction (LLX) modeling. The LLX data were achieved from experiments with conditions being Alamine 336 concentrations of 0.1–10% v/v from a solution containing about 1.378 mmol/L Ge (100 mg/L) and tartaric acid as an anionic complexant. The LLX model was attained using the equilibrium-based procedure and fitted to extraction experimental data for various carrier concentrations. This model presented an accurate extraction constant (K _ext = 0.02) used in the facilitated transport modeling. The flat sheet supported liquid membrane (FSSLM) experiments were conducted in the condition of 1.378 mmol/L Ge (100 mg/L), tartaric acid concentration of 2.760 mmol/L, 1 M HCl as a stripping phase and various Alamine 336 concentrations in the range of 0–35% v/v. The FSSLM model was developed according to the Fick’s law, the diffusional transport, and equilibrium equations. According to the model, mass transfer and diffusion coefficients for various concentrations of the carrier were found. In addition, the calculated and experimental values had a good correlation with together showing the validity of the model. This model can be used in the further process simulation such as hollow fiber SLMs.     

Immobilization of glucose oxidase on ZnO nanorods decorated electrolyte-gated field effect transistor for glucose detection

In this paper, we report on growth of ZnO nanorods on the surface of gold interdigital electrodes and its implementation as a conductive n-type channel for the fabrication of a liquid-gated field effect transistor. Glucose oxidase was immobilized on the surface of the ZnO nanorods and the fabricated device was used as a four-electrode glucose biosensor. The resistance of the conductive channel was affected by addition of glucose. The applied bias voltage to the gate in the fabricated device affects the channel resistance in the same manner as the increase of enzymatic products during the glucose oxidation. Large effective area, good conductivity, and biocompatibility properties of ZnO nanorods are the key features in this highly sensitive and stable biosensor. Our measurements showed that the threshold voltage of transistor was about 0.75 V. The current increased in the presence of the glucose and exhibited a dynamic linear range with the logarithm of glucose concentration in the range between 0.01 and 5 mM. The detection limit was about 3.8 μM.     

Release and extraction of letrozole in blood plasma using resorcinol functionalized multi-walled carbon nanotube coupled with high-performance liquid chromatography

In this research, carboxylated multi-walled carbon nanotube was functionalized by cyanuric chloride and modified by 1,3 dihydroxybenzene (MWCNT-resorcinol). MWCNT-resorcinol was used as an adsorbent for extraction and determination of letrozole in human blood plasma prior to high-performance liquid chromatography equipped with ultraviolet detector (HPLC-UV). Synthesized carbon nanotubes were modified and characterized using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The efficiency of the adsorbent for adsorption and release of letrozole in the blood plasma was evaluated at the optimized condition. An adsorption efficiency of 96.9% was achieved at pH of 4 and the extraction time of 20?min. A recovery percentage of 92.7% for the drug in plasma was also obtained. Lastly, the release efficiency values for letrozole from MWCNTs-resorcinol in simulated gastric fluid (pH 1.2) and simulated intestinal fluid (pH 7.4) were calculated as 91% and 70%, respectively. Such results enhanced the potential ability of the MWCNTs-resorcinol as a drug delivery substrate.     

A review on geothermal Organic Rankine cycles: modeling and optimization

Journal of Thermal Analysis and Calorimetry - Employing renewable energy sources for power generation have been developed in recent years due to their several benefits including low emission of...     

Thiol-Functionalized Palladium Nanoparticles Networks: Synthesis,Characterization, and Room Temperature (Toxic) Vapor Detection

The preparation of three different functionalized palladium nanoparticles (PdNPs) systems for room temperature BTX (benzene, toluene, p-xylene) sensing detection and their morphostructural characterization is described. PdNPs are prepared through a two-phase water/toluene wet chemical reduction method in the presence of bifunctional organic thiols as stabilizing agents suitable for the formation of covalently linked PdNPs networks: p-terphenyl-4,4″-dithiol (PdNPs-TR), biphenyl-4,4′-dithiol (PdNPs-BP), or with 9,9-didodecyl-2,7-bis(acetylthio)fluorene (PdNPs-FL). Comparing the hydrodynamic diameter values, TR and BP ligands help to obtain networks consisting of spherical NPs of about 2 nm, in which each bifunctional ligand act as a bridge between PdNPs. In contrast, PdNPs-FL show a population centered at <2R_H> = 45 ± 5 nm. To perform preliminary gas sensing measurements, PdNPs networks are cast deposited on interdigitated electrodes to study their resistive response toward volatile organic compounds (VOCs) such as benzene (0–5%), toluene (0–1.7%), and p-xylene (0–0.4%) (BTX) and common interfering gases (H₂S, NH₃, SO₂, and relative humidity, RH). PdNPs-FL show enhanced response to BTX with an appreciable response also toward H₂S and RH. PdNPs-TR exhibit a better ability to discriminate benzene gas with a negligible response after H₂S exposure. Moreover, all the PdNPs systems show little to no response to NH₃ and SO₂ gases, offering an interesting perspective in practical sensing applications.     

Transport properties of Mie(14,7) fluids: molecular dynamics simulation and theory

An extensive computer simulation study is presented for the self-diffusion coefficient, the shear viscosity, and the thermal conductivity of Mie(14,7) fluids. The time-correlation function formalism of Green-Kubo is utilized in conjunction with molecular dynamics (MD) simulations. In addition to molecular simulations, the results of a recent study [A. Eskandari Nasrabad, J. Chem. Phys. 128, 154514 (2008)] for the mean free volume are applied to calculate the self-diffusion coefficients within a free volume theory framework. A detailed comparison between the MD simulation and free volume theory results for the diffusion coefficient is given. The density fluctuation theory of shear viscosity is used to compute the shear viscosity and the results are compared to those from MD simulations. The density and temperature dependences of different time-correlation functions and transport coefficients are studied and discussed.     

Separation and Assay of Cholecalciferol in Vitamin A + D Ointment

Summary. In this paper two methods are presented. One involves the separation of cholecalciferol from a topical ointment. The other involves the assay of cholecalciferol in this ointment. The study was performed with normal-phase high performance liquid chromatography using a NP-L3 column and UV detection. Applying a mobile phase mixture containing n-hexane:2-propanol (99:1) a total separation was achieved within 15 min. For isolation and assay of cholecalciferol from an ointment (vitamin A + D), dissolution in n-hexane gave the highest recovery (>95%). The isolation and assay process can be performed within 3.5 h.     

Hydrothermal synthesis and physicochemical characterization of CuO/ZnO/Al2O3 nanopowder. Part I: Effect of crystallization time

A hydrothermal method was successfully used for synthesis of CuO/ZnO/Al₂O₃ (CZA) nanopowder with atomic ratio of 6:3:1. The effect of crystallization time (3, 6, 9, and 12 h) on physicochemical properties of nanopowder was investigated. Nanopowders were characterized using XRD, FESEM, EDX, FTIR, TG, and BET techniques. The XRD patterns confirmed metal oxides formation and their good crystallinity with average crystallite size of 20 nm as obtained by the Scherrer equation. Relative crystallinity was shown to increase with increasing crystallization time. In agreement with XRD results, FESEM images also illustrated nanosized particles. EDX mapping indicated homogenous dispersion of elements. BET specific surface area analysis showed acceptable surface area for CZA nanopowder. FTIR spectroscopy confirmed metal oxides formation during hydrothermal and calcination processing. TG results illustrated high thermal stability of the synthesized nanopowders. TG-DTG and FTIR analyses were used to propose a reaction mechanism for nanopowder formation during processing. Physicochemical characterization showed optimal crystallization time to be 6 h.     

Buckling Behavior of Carbon Nanotubes Functionalized with Carbene under Physical Adsorption of Polymer Chains: a Molecular Dynamics Study

The buckling analysis of functionalized carbon nanotubes (CNTs) is of great importance for the better understanding of mechanical behavior of nanocomposites. The buckling behavior of carbene-functionalized CNTs (cfCNTs) under physical adsorption of polymer chains (cfCNTs/polymers) is studied in this paper by the classical molecular dynamics (MD) simulations. In this regard, to investigate the interactions between non-covalent polymer chains and cfCNTs, two different non-covalent functional groups, i.e. polycarbonate (PC) and polypropylene (PP), are selected. The findings are compared with those of pure CNTs under the physical adsorption of polymer chains (pCNTs/polymers). The obtained results show that at a given weight percentage of non-covalent functional groups, the gyration radius of cfCNTs/polymers is higher than that of pCNTs/polymers. Furthermore, an increase in the critical buckling force of cfCNTs/polymers is dependent on the type of non-covalent polymer chains. For cfCNTs/PC and cfCNTs/PP, the critical buckling force is respectively lower and higher than that of pCNTs/polymers for the similar weight percentage of non-covalent functional groups. In addition, it is found that the critical buckling strain of cfCNTs/polymers is smaller than that of pCNTs/polymers for the same weight percentage of non-covalent polymer chains.