Cr(III)-imprinted polymeric beads: Sorption and preconcentration studies

The purpose of this study is to prepare a novel molecular imprinted adsorbent to Cr(III) analysis with high selectivity. Initially, chromium (III)-methacryloylhistidine (MAH/Cr(III)) complex monomer was synthesized and then Cr(III) ion imprinted ethyleneglycoldimethacrylate-methacryloylhistidine (poly(EDMA-MAH/Cr(III))) was polymerized. Cr(III) ions were removed from the Cr(III)-imprinting polymer. Selective cavity for the chromium (III) ions was obtained in the (poly(EDMA-MAH/Cr(III))) beads. These Cr(III)-imprinted beads were used in the sorption-desorption process. The effect of initial concentration of metal, the sorption rate and the pH of the medium on sorption capacity of Cr(III)-imprinting sorbents were studied. Sorption equilibrium time was achieved in about 30min. The maximum sorption of Cr(III) ions onto imprinted beads was about 69.28mg/g. Sorption studies of Co(II), Ni(II), Cr(III) and Cr(VI) ions were also investigated using Cr(III)-imprinting polymers. The obtained results show that selectively adsorbed amount of Cr(III) ion on Cr(III)-imprinting polymers is higher than all other studied ions. When the beads were used repeatedly, their adsorption capacity was showed feasibility.     

Sintering and microstructure characteristics of 42CrMo4 steel processed by spark plasma sintering

Rapidly solidified micron sized 42CrMo4 steel powder with a size range of 150–250 μm produced by plasma rotating electrode process was consolidated using a recently developed spark plasma sintering (SPS) process. The relationship between sintering parameters (temperature and soaking time) and microstructural properties was investigated. The effect of slow and high heating regimes on the consolidation of sintered compacts has been also investigated. Maximum relative density (99.2%) was obtained at 1000 °C, under 50 MPa pressure, with 8 min holding time and 200 °C/min heating rate. The microstructure of sintered steel was influenced by carburization occuring inside the graphite SPS process die. The diffusion of carbon produced martensite structure near the surface region and hardened the surface. This effect was investigated in detail using optical microscopy and hardness measurement. Scanning electrone microscopy was also used to examine the fracture surface of sintered compacts. High heating rate promoted the relative density at low temperature compared to high temperature.     

4-Aminophenyl boronic acid modified gold platforms for influenza diagnosis

As a potential pandemic threat to human health, there has been an urgent need for rapid, sensitive, simpler and less expensive detection method for the highly pathogenic influenza A virus. For this purpose, Quartz Crystal Microbalance (QCM) and Surface Plasmon Resonance (SPR) sensors have been developed for the recognition of hemagglutinin (HA) which is a major protein of influenza A virus. 4-Aminophenyl boronic acid (4-APBA) has been synthesized and used as a new ligand for binding of sialic acid (SA) via boronic acid–sugar interaction. SA has an important role in binding of HA. QCM and SPR sensor surfaces have been modified with thiol groups and then 4-APBA and SA have been immobilized on sensor surfaces, respectively. Sensor surfaces have been screened with AFM and used for the determination of HA from aqueous solution. The selective recognition of the QCM and SPR sensors toward Concanavalin A has been reported in this work. Also, the binding capacity and detection limits of QCM and SPR sensors have been calculated and detection limits were found to be 4.7 × 10^? 2 μM, (0.26 μg ml^? 1) and 1.28 × 10^? 1 μM, (0.72 μg ml^? 1) in the 95% confidence interval, respectively.     

Investigation of Rubber-to-Metal Bonding on Solid Rubber Tires

The knowledge on rubber-to-metal adhesion, which is an important issue in manufacturing processes of some automotive and aircraft parts and solid rubber tires, is generally confined within the patented information. This study investigates the factors contributing to the ability to produce strong and permanent rubber-to-metal bonds. Consideration is given to the material factors and methods of surface preparation, for which the quantitative data available in the open literature are very limited. Bonding strengths achieved by two different surface preparation methods are compared. Also discussed are percent elongation, bonding strength, and tensile strength measurements on the samples prepared in accordance with the solid tire recipe and cured at 140°, 150°, 160°, and 170°C. The effect of molding forces on rubber-to-metal bonding is established by applying different force values. The use of “cushion gum” as adhesion medium is proposed as a new way of obtaining successful rubber-to-metal bonding. The effect of the thickness of cushion gum layer on bond strength is presented.     

Obstructive sleep apnoea among professional taxi drivers: A pilot study

Purpose

This study aimed to describe the distribution of risk factors for obstructive sleep apnoea syndrome (OSAS) among taxi drivers, and to investigate differences by ethnicity in OSAS symptoms among drivers.

Methods

A two-page postal questionnaire was completed by 241 professional taxi drivers from Wellington, New Zealand. Obstructive sleep apnoea syndrome was defined as having an estimated 15 or more respiratory disturbances, per hour of sleep (Respiratory Disturbance Index (RDI) ≥ 15) and self-reported daytime sleepiness.

Results

Pacific and Māori taxi drivers were more likely to have symptoms and risk factors for OSAS, compared to non-Māori non-Pacific drivers. In particular, Pacific drivers had a significantly increased pre-test probability of having moderate-severe OSA (RDI ≥ 15).

Conclusions

Some professional taxi drivers are at increased risk for moderate-severe OSAS, especially Pacific and Māori taxi drivers. Untreated OSAS increases motor vehicle crash risk, so these findings have implications for the health and safety of drivers and their passengers. They suggest a need for more comprehensive research to guide policy on medical examinations required for licensing professional drivers as fit to drive.     

Immunoglobulin G recognition with Fab fragments imprinted monolithic cryogels: Evaluation of the effects of metal-ion assisted-coordination of template molecule

In this study, we applied the epitope imprinting approach to prepare molecularly imprinted monolithic cryogels for immunoglobulin G (IgG) recognition. In this respect, we imprinted F_ab fragments of IgG molecules instead of intact protein molecules via two different non-covalent interactions. In the first approach, we directly coordinated F_ab fragments with N-methacryloyl-L-histidine (MAH), polymerizable derivative of L-histidine, but for the second, we used cupric ions [Cu(II)] as mediator between MAH and F_ab fragments. The monolithic cryogels were characterized by Fourier transform infrared (FTIR) spectroscopy, swelling test, and scanning electron microscopy. Then, the monolithic cryogels were used for F_ab fragment adsorption from aqueous solution while evaluating the factors such as pH and F_ab fragment concentration affecting on adsorption process in continuous set-up. After that, monolithic cryogels were used for IgG adsorption by varying pH, IgG concentration, flowrate, and temperature in appropriate ranges. Maximum IgG adsorption capacities were determined as 32.4 mg/g and 49.0 mg/g for directly coordinated cryogel (MIP_Direct) and Cu(II) assisted cryogel (MIP_{Cu(II) assisted}), respectively. Non-imprinted monolithic cryogels were also prepared for control purposes. In addition to F_ab fragments and IgG molecules, albumin and F_c fragment of IgG molecules were used as competitor biomolecules in order to investigate the selectivity gained by imprinting process. Relative selectivity constants were calculated as 1.47, 2.64 and 3.89 for MIP_Direct and 2.90, 8.98, and 11.51 for MIP_{Cu(II) assisted} for F_ab/IgG, F_ab/F_c, and F_ab/albumin as biomolecule pairs, respectively. The desorption efficiency and reusability of MIP_{Cu(II) assisted} cryogel were better than that of MIP_Direct. The results reported here showed that the metal ion assistance improved the selectivity features of the imprinted cryogels and allowed to study under milder conditions with enhanced adsorptive properties.     

New Magnesium Composite with Mg17Al12 Intermetallic Particles

Powder Metallurgy and Metal Ceramics - Although magnesium is one of the materials with the lowest density, its application is limited amongst other commercial materials due to insufficient...     

Developing an Adaptation Process for Real-Coded Genetic Algorithms

The genetic algorithm (GA) is a metaheuristic method which simulates the life cycle and the survival of the fittest in the nature for solving optimizationproblems. This study aimed to develop enhanced operation by modifying the current GA. This development process includes an adaptation method thatcontains certain developments and adds a new process to the classic algorithm. Individuals of a population will be trialed to adapt to the current solution ofthe problem by taking them separately for each generation. With this adaptation method, it is more likely to get better results in a shorter time. Experimentalresults show that this new process accelerated the algorithm and a certain solution has been reached in fewer generations. In addition, better solutions wereachieved, especially for a certain number of generations.     

Fabrication of Gentamicin Sulfate-Loaded 3D-Printed Polyvinyl Alcohol/Sodium Alginate/Gelatin-Methacryloyl Hybrid Scaffolds for Skin Tissue Replacement

3D-printed scaffolds can better mimic the function of human skin, both biologically and mechanically. Within the scope of this study, the effect of the addition of different amounts (10, 15, 20 mg) of gentamicin sulfate (GS) to a 10 mL solution of natural and synthetic polymers is investigated. Sodium alginate (SA), gelatin-methacryloyl (GelMA), and polyvinyl alcohol (PVA) are chosen as bioactive materials. The surface morphology and pore structures are visualized by scanning electron microscopy (SEM). According to the results, it is observed that the pore sizes of all scaffolds are smaller than 270 µm, the lowest value (130 µm) is obtained in the scaffold loaded with 15 mg GS, and it also has the highest tensile strength value (12.5 ± 7.6 MPa). Similarly, it is observed that the tensile strength (9.7 ± 4.5 MPa) is high in scaffold loaded with 20 mg GS. The biocompatibility test is performed with fibroblast cells, and the results show that the scaffolds are biocompatible with cells. The antibacterial test is carried out against the S.aureous and E. coli and the results indicate that all GS-loaded scaffolds demonstrate antibacterial activity.     

Supermacroporous poly(hydroxyethyl methacrylate) based cryogel with embedded bilirubin imprinted particles

Molecular imprinted polymers are artificial, template-made materials with the ability to recognize and to specifically bind the target molecule. The aim of this study is to prepare supermacroporous cryogel with embedded bilirubin-imprinted particles which can be used for the selective removal of bilirubin from human plasma. N-methacryloyl-(l)-tyrosinemethylester (MAT) was chosen as the pre-organization monomer. In the first step, bilirubin was complexed with MAT and the bilirubin-imprinted poly(hydroxyethyl methacrylate-N-methacryloly-(l)-tyrosine methyl-ester) [MIP] monolith was produced by bulk polymerization. MIP monolith was smashed and the particles ground and sieved through 100 μm sieves. In the second step, the supermacroporous poly(hydroxyethyl methacrylate) (PHEMA) cryogel with embedded MIP particles [PHEMA/MIP composite cryogel] was produced by free radical polymerization initiated by N,N,N′,N′-tetramethylene diamine (TEMED) and ammonium persulfate (APS) pair in an ice bath. After that, the template (i.e., bilirubin) molecules were removed using sodium carbonate and sodium hydroxide. Compared with the PHEMA cryogel (0.2 mg/g polymer), the bilirubin adsorption capacity of the PHEMA/MIP composite cryogel (10.3 mg/g polymer) was improved significantly due to the embedded MIP particles into the polymeric matrix. The relative selectivity coefficients of PHEMA/MIP composite cryogel for bilirubin/cholesterol and bilirubin/testosterone were 8.6 and 4.1 times greater than the PHEMA cryogel, respectively. The PHEMA/MIP composite cryogel could be used many times without decreasing the bilirubin adsorption capacity significantly.