Effect of impression valve system on adhesion force of impression materials to edentulous maxillary jaw: a preliminary clinical study

Objective: The purpose of this preliminary clinical study was to evaluate the effect of novel impression valve system (IVS) on adhesion force of different impression materials to edentulous maxilla. Background data: Impression materials and techniques have an important role in complete denture success. During the functional impression with an individual impression tray (IIT), high adhesive forces exist between edentulous ridge and impression material. Removing the IIT from the mouth with minimal force provides the most accurate and non-deformed impression. Materials and methods: This study included twenty maxillary edentulous patients (n?=?20). Patients who had palatal torus, anatomic undercut, gagging reflex, and flabby ridges were excluded from the study. The age range of the participants was 55–70. All patients gave written informed consent. Two impression materials – zinc oxide eugenol (ZOE) and alginate – were used as experimental material. The digital dynamometer was used to determine the adhesion force of impression materials with and without IVS to edentulous maxilla. The mean values of the adhesion forces were analyzed using the Wilcoxon signed-ranks test (α = 0.05). Results: The effect of IVS on adhesion force was found to be statistically significant (p < 0.05). There were also statistical differences between the ZOE and alginate groups (p < 0.05). Conclusions: The IVS is useful to remove the functional impression from the mouth without any deformation and detaching in cases which high adhesive force occurs.     

In situ Van der Pauw measurements of the Ni/YSZ anode during exposure to syngas with phosphine contaminant

Solid oxide fuel cells (SOFCs) represent an option to provide a bridging technology for energy conversion (coal syngas) as well as a long-term technology (hydrogen from biomass). Whether the fuel is coal syngas or hydrogen from biomass, the effect of impurities on the performance of the anode is a vital question. The anode resistivity during SOFC operation with phosphine-contaminated syngas was studied using the in situ Van der Pauw method. Commercial anode-supported solid oxide fuel cells (Ni/YSZ composite anodes, YSZ electrolytes) were exposed to a synthetic coal syngas mixture (H₂, H₂O, CO, and CO₂) at a constant current and their performance evaluated periodically with electrochemical methods (cyclic voltammetry, impedance spectroscopy, and polarization curves). In one test, after 170 h of phosphine exposure, a significant degradation of cell performance (loss of cell voltage, increase of series resistance and increase of polarization resistance) was evident. The rate of voltage loss was 1.4 mV h⁻¹. The resistivity measurements on Ni/YSZ anode by the in situ Van der Pauw method showed that there were no significant changes in anode resistivity both under clean syngas and syngas with 10 ppm PH₃. XRD analysis suggested that Ni₅P₂ and P₂O₅ are two compounds accumulated on the anode. XPS studies provided support for the presence of two phosphorus phases with different oxidation states on the external anode surface. Phosphorus, in a positive oxidation state, was observed in the anode active layer. Based on these observations, the effect of 10 ppm phosphine impurity (or its reaction products with coal syngas) is assigned to the loss of performance of the Ni/YSZ active layer next to the electrolyte, and not to any changes in the thick Ni/YSZ support layer.     

Power quality assessment of grid-connected wind farms considering regulations in turkey

This paper presents measurement system and detailed analysis of power quality at the substation of two different wind farm sites which are of low and high power rate. Measurement system has been designed using a data acquisition board (DAQ), Labview software, Matlab programming and a portable PC. The system has been installed at medium voltage level at substation of both wind farms. The real measurement results at substations are compared to current regulations in Turkey.     

A traditional cheese from Greece to Turkey: Armola

In the present study, red capia pepper, broccoli, pumpkin, carrot purees and a probiotic culture containing Lactobacillus acidophilus were added to the conventionally produced Armola cheese to improve the functional properties of the cheese. The analyses showed that there were significant differences between the physicochemical and functional properties of the cheese samples. The samples containing broccoli had the highest antioxidant activity. Except for the control sample, L. acidophilus counts in Armola cheese samples were found to be 10⁶ log cfu/g on day 30 and the samples were found to maintain their probiotic properties until the end of the storage period.     

Mathematical modeling of heat recovery from a rotary kiln

In this study, heat recovery from rotary kiln was examined for a cement plant in Turkey. At first, an exergy analysis was carried out on the operational data of the plant. Results indicated the presence of 217.31 GJ of waste heat, which is 51% of the overall heat of the process. Then a mathematical model was developed for a new heat recovery exchanger for the plant. It was determined that 5% of the waste heat can be utilized with the heat recovery exchanger. The useful heat obtained is expected to partially satisfy the thermal loads of 678 dwellings in the vicinity through a new district heating system. This system is expected to decrease domestic-coal and natural gas consumption by 51.55% and 62.62% respectively. CO₂ emissions may also be reduced by 5901.94 kg/h and 1816.90 kg/h when waste heat is used instead of coal and natural gas.     

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.     

Indirect electrochemical treatment of bisphenol A in water via electrochemically generated Fenton's reagent

Bisphenol A (BPA) has been treated with electrochemically generated Fenton's reagent in aqueous medium. Hydroxyl radicals that were formed in Fenton's reagent reacted with the organic substrate producing two different isomers of monohydroxylated product and, upon successive hydroxylation, mainly one dihydroxylated product. Further hydroxylation first degraded one of the aromatic rings, and the side chain thus formed was then cleaved off the other aromatic ring. The second aromatic ring was also degraded upon successive hydroxylations. Small saturated and unsaturated aliphatic acids were the last products prior to mineralization. It was found that use of cuprous/cupric ion pair resulted a faster conversion of BPA and faster mineralization when compared using ferrous/ferric ions, but this happened at the expence of excess electrical charge utilized for an equivalent conversion or mineralization. Degradation by using ferrous/ferric ions was more efficient than cuprous/cupric ions case in terms of total mineralization versus charge utilized, and a mineralization of 82% had been achieved by applying 107.8 mF of charge to a 0.7 mM BPA solution of 0.200 dm3. The rate constant of the monohydroxylation of BPA in the presence of ferrous/ferric ions had been determined as 1.0 x 10(10) M(-1) s(-1) where BPA and salicylic acid competitively reacted with hydroxyl radicals in aqueous medium with the initial concentrations of Fe2+, BPA, and SA of 1.0, 0.5, and 0.5 mM, respectively. In a similar experiment where the initial concentrations of Cu2+, BPA, and SA were 1.0, 0.5, and 0.5 mM, respectively, the corresponding rate constant was determined to be the same as the rate constant obtained for Fe2+ (i.e., 1.0 x 10(10) M(-1) s(-1)). While the use of Cu2+ cannot be advised for processing BPA and similar substrates by using the electro-Fenton technique for both technical and economical reasons, the use of [Fe2+]/[BPA]0 values in the range 3-4 will be sufficient to achieve an efficient mineralization of BPA and similar substrates by the electro-Fenton process in aqueous medium.     

Microbiological aspects and challenges of whey powders – I thermoduric,thermophilic and spore-forming bacteria

For dairy processors, spoilage and pathogenic spore-forming bacteria are key sources of concern, not only due to their ability to remain dormant in a desiccated state in powders and to survive heat treatments, but also their ability to form biofilms in the vegetative state that lead to contamination of foods. These include members of the genera Bacillus, Geobacillus, Anoxybacillus, Brevibacillus, Paenibacillus and Clostridium, many of which are associated with food poisoning and spoilage. Here, we review the common bacterial species that form spores in whey powders and their sources and provide insights into their risks and strategies to control them.     

Hydrolysis of kenaf (Hibiscus cannabinus L.) stems by catalytical thermal treatment in subcritical water

The present study was designed to solubilize/hydrolyze lignocellulosic biomass of kenaf stems in subcritical water, in an environmentally friendly manner. The hydrolysis efficiency was examined with respect to several parameters such as sonication of biomass-water mixture before thermal treatment, changing temperature and pressure of the hydrolysis process, adding carbon dioxide or nitrogen as pressurizing gas.The molar mass of polysaccharide fractions in the sonication pretreated solutions notably decreased because of effective degradation. The extent of hydrolysis was more effective at higher temperatures and under carbon dioxide atmosphere rather than nitrogen as the pressurizing gas. In comparison to untreated sample, 200 °C-subcritical water-treated kenaf stems had significant morphological and structural changes on plant cell wall surface that was further distorted at 250 °C.     

Evaluation of various carbon materials supported Pt catalyts for aqueous-phase reforming of lignocellulosic biomass hydrolysate

Currently, under huge pressure from energy demands and environmental problems, much attention is being paid to produce fuel and chemicals from lignocellulosic biomass. In this matter, development of active and also recyclable catalysts are essential. In the present study, various types of carbon supported Pt reforming catalysts were prepared for use in gasification of wheat straw biomass hydrolysate by aqueous-phase reforming. The supports tested were various carbon materials having different surface and structures that were activated carbon (AC), single- and multi-walled carbon nanotubes (SWCNT and MWCNT), superdarco carbon (SDC) and graphene oxide (GO). The catalysts prepared using these supports were evaluated based on gasification yield, carbon amount consumed in the process, sugar alcohols formation and breaking down of organic compounds in the hydrolysate.