A new instrumental setup for determination of small amplitude viscoelastic properties of dough during fermentation

In this study, the working principles and the theoretical background of a new method to measure the viscoelastic properties of dough in the fermentation process are presented. During measurements, the dough sample was placed between a stationary bottom plate and an oscillating top plate and squeezed at random frequencies ranging from 10 to 100,000 rad/s. By measuring the required force and velocity of oscillations, the mechanical impedance of the samples, defined as the ratio of the force to oscillation velocity, was determined during fermentation. The measured mechanical impedance was used to calculate viscoelastic properties such as elastic and loss moduli of the dough samples. The nondestructive quick measurements and data covering a wide range of frequencies are some of the main advantages of the method. Furthermore, the described instrument can be easily affixed to the commonly available texture analyzer type equipments.     

Synthesis and characterization of magnetic polyHIPEs with humic acid surface modified magnetic iron oxide nanoparticles

Magnetic macroporous polymer monoliths have been prepared using styrene/divinylbenzene (S/DVB) high internal phase emulsions (HIPEs) as templates. Humic acid surface modified iron oxide magnetic nanoparticles (Fe₃O₄@HA) have been used to prepare magnetic emulsion templates. The effect of magnetic particle concentration has been investigated by changing the ratio of Fe₃O₄@HA nanoparticles in the continuous phase. Highly macroporous polymers with magnetic response were obtained by the removal of the internal phase after the curing of emulsions at 80 °C. Fe₃O₄@HA particles were characterized by XRD and FTIR. The porosity, pore morphology and magnetic properties of the macroporous polymers were characterized as a function of the Fe₃O₄@HA concentration by scanning electron microscopy (SEM), Brunauer–Emmet–Teller (BET) molecular adsorption method and vibrating sample magnetometry (VSM), respectively. BET and VSM measurements demonstrated that the specific surface area and the saturation magnetization of the polymer monoliths were changed according to the Fe₃O₄@HA concentration between 8.77–35.08 m² g^?1 and 0.63–11.79 emu g^?1, respectively. Resulting magnetic monoliths were tested on the adsorption of Hg(II) and atomic absorption spectroscopy (AAS) was used to calculate the adsorption capacities. The maximum adsorption capacity of the magnetic monoliths was calculated to be 20.44 mmol g^?1 at pH 4.     

Distribution of interface traps in Au/2% GC-doped Ca3Co4Ga0.001Ox/n-Si structures

This study presents voltage-dependent profile of interface traps in Au/n-Si structure with 2% graphene–cobalt-doped Ca₃Co₄Ga_0.001O_x interfacial layer. Admittance measurements revealed capacitance-voltage (C-V) plots with typical regions of a metal–insulator–semiconductor structure through inversion, depletion, and accumulation regions. Frequency dispersion is observed in C-V plots and such behavior was explained with excess capacitance, which is associated with the density of interface traps (D_it) in the structure because larger D_it is observed when the measurements are held at low frequencies due to the fact that traps can follow the signal depending on their lifetime. D_it was also obtained using conductance method, which also provided lifetime of the traps. The difference between the values of D_it was attributed to the difference in extraction methods. Obtained results showed that Au/2% graphene–cobalt-doped Ca₃Co₄Ga_0.001O_x/n-Si structure yields promising electrical characteristics when the structure is operated at high frequencies. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48399.     

Purification of alginate and feasible production of monoclonal antibodies by the alginate-immobilized hybridoma cells

Alginate has an extensive usage in the immobilization of many cell types. Although they have high biocompatibility, commercial alginates contain various degrees of contaminants such as polyphenols, endotoxins and proteins. Thus, these alginates show cytotoxicity against sensitive cell types such as hybridoma cells. In the studies so far, owing to this fact, commercially purchased high-priced ultrapure alginates have been used in the immobilization of hybridoma cells for monoclonal antibody production. However in this study, as a novelty, low-priced commercial alginate was purified, and then the cultivation of alginate-immobilized hybridoma cells was performed for feasible monoclonal antibody production. Low-priced commercial alginate was purified with a profitability ratio of 40%. Then, an optimized immobilization procedure was conducted effectively by using the purified alginate. During more than 25 days of cultivation, serum concentration was kept low, and approximately 2 times greater monoclonal antibody production was achieved, in comparison with its free suspended counterpart. The results showed that the efficiency of monoclonal antibody production via alginate-immobilized hybridoma cultivation can be increased by performing a proved in-house purification method. By shedding light on the efficiency of the in-house purification method, the results also indicated a feasible way of monoclonal antibody production.     

Torsional Wave Propagation in the Finitely Pre-Stretched Hollow Bi-Material Compound Circular Cylinder

This paper studies the torsional wave dispersion in the hollow bi-material compounded cylinder with finite initial strains. The investigations are carried out within the scope of the piecewise homogeneous body model with the use of the three-dimensional linearized theory of elastic waves in initially stressed bodies. The mechanical relations of the materials of the cylinders are described through the harmonic potential. The numerical results on the influence of the initial stretching or compression of the cylinders along the torsional wave propagation direction are presented and discussed     

Multi-model sensor fault detection and data reconciliation: A case study with glucose concentration sensors for diabetes

Erroneous information from sensors affect process monitoring and control. An algorithm with multiple model identification methods will improve the sensitivity and accuracy of sensor fault detection and data reconciliation (SFD&DR). A novel SFD&DR algorithm with four types of models including outlier robust Kalman filter, locally weighted partial least squares, predictor-based subspace identification, and approximate linear dependency-based kernel recursive least squares is proposed. The residuals are further analyzed by artificial neural networks and a voting algorithm. The performance of the SFD&DR algorithm is illustrated by clinical data from artificial pancreas experiments with people with diabetes. The glucose-insulin metabolism has time-varying parameters and nonlinearities, providing a challenging system for fault detection and data reconciliation. Data from 17 clinical experiments collected over 896 h were analyzed; the results indicate that the proposed SFD&DR algorithm is capable of detecting and diagnosing sensor faults and reconciling the erroneous sensor signals with better model-estimated values. © 2018 American Institute of Chemical Engineers AIChE J, 65: 629–639, 2019     

Polyamide 66 binary and ternary nanocomposites: Mechanical and morphological properties

Polyamide 66 (PA 66)/impact modifier blends and polyamide/organoclay binary and PA 66/organoclay/impact modifier ternary nanocomposites were prepared by the melt‐compounding method, and the effects of the mixing sequences on the morphology and mechanical and flow properties were investigated. Lotader AX8840 and Lotader AX8900 were used as impact modifiers. The concentrations of the impact modifiers and the organoclay (Cloisite 25A) were maintained at 2 and 5 wt %, respectively. Both the binary and ternary nanocomposites displayed high tensile strength and Young's modulus values compared to the PA 66/impact modifier blends. Decreases occurred in the strength and stiffness of the binary nanocomposites upon incorporation of the elastomeric materials into the polymeric matrix. In general, the mixing sequence in which all three ingredients were added simultaneously and extruded twice (the All‐S mixing sequence) exhibited the most enhanced mechanical properties in comparison with the mixing sequences in which two of the components were extruded in the first extrusion step and the third ingredient was added in the second extrusion step. The mechanical test results were in accordance with the organoclay dispersion. The impact strength was highly affected by the elastomeric domain sizes, interdomain distances, interfacial interactions, and organoclay delamination. The smallest elastomeric domain size was obtained for the All‐S mixing sequence, whereas the elastomeric domain sizes of the other mixing sequences were quite close to each other. Drastic variations were not observed between the melt viscosities of the ternary nanocomposites prepared with different mixing sequences. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Removal of acidic dye from aqueous solutions using poly(DMAEMA–AMPS–HEMA) terpolymer/MMT nanocomposite hydrogels

In this study, poly(DMAEMA–AMPS–HEMA) terpolymer/montmorillonite nanocomposite hydrogels were prepared by in situ polymerization technique using 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA), 2-acrylamido-2-methlypropane sulfonic acid (AMPS), 2-hydroxyethyl methacrylate (HEMA) monomers in clay suspension media. N,N-methylenebisacrylamide (NMBA) was used as crosslinker and potassium persulfate/potassium bisulfide were used as initiator and accelerator pair. The water absorption capacities and acidic dye (indigo carmine) adsorption properties of the nanocomposite hydrogels were investigated. Adsorption properties of the hydrogels were investigated at different conditions such as different initial dye concentration and contact time. The concentrations of the dyes were determined using UV/Vis Spectrophotometer at wavelength 610 nm. Langmuir and Freundlich isotherm models were used to describe adsorption data and the results clarified that these models were the best-fit for the adsorption of indigo carmine.