Strawberry drying: Development of a closed-cycle modified atmosphere drying system for food products and the performance evaluation of a case study

In the present study, a closed-cycle modified atmosphere drying (CC-MAD) system was developed as an alternative drying technique to facilitate drying processes for agricultural commodities appropriate to highly humid and sunny regions with a better quality. An absorption dehumidifying system was designed for working pseudo-continuously with the most efficient absorbent in terms of moisture absorption, desorption rate, and capacity. The system, assisted by a solar panel for absorbent regeneration, was tested, while its optimum working condition was determined by strawberry drying. This unique process was comparatively carried out using hot-air and freeze-drying techniques in terms of processing time and final product quality. Strawberry slices (5?mm thickness) were dried successfully using CC-MAD. The optimum drying conditions of CC-MAD were determined as drying temperature of 60°C, drying air/gas velocity of 3?m/s and drying medium oxygen level of 9.47%. The loss of ascorbic acid was significantly reduced by CC-MAD technique. These losses were found to be 2.9, 6.9, 27.2, and 23.8% by freeze-drying, CC-MAD, hot-air drying, and hot-air drying combined with CC-MAD, respectively. The total monomeric anthocyanins loss was also significantly reduced by the CC-MAD technique (20.3%), in a similar way to that of freeze-drying (18.1%) in comparison with hot-air drying (40.4%). In addition, CC-MAD (12,446?kJ/kg fresh product at 4?h drying time) is three times more advantageous in terms of energy cost compared with freeze-drying (30492.8?kJ/kg fresh product at 24?h drying time) and six times faster in terms of drying time. This new drying system can be used as an alternative to freeze-drying in the drying of foods, especially in products sensitive to oxidation.     

Multimodal emotion recognition based on peak frame selection from video

We present a fully automatic multimodal emotion recognition system based on three novel peak frame selection approaches using the video channel. Selection of peak frames (i.e., apex frames) is an important preprocessing step for facial expression recognition as they contain the most relevant information for classification. Two of the three proposed peak frame selection methods (i.e., MAXDIST and DEND-CLUSTER) do not employ any training or prior learning. The third method proposed for peak frame selection (i.e., EIFS) is based on measuring the “distance” of the expressive face from the subspace of neutral facial expression, which requires a prior learning step to model the subspace of neutral face shapes. The audio and video modalities are fused at the decision level. The subject-independent audio-visual emotion recognition system has shown promising results on two databases in two different languages (eNTERFACE and BAUM-1a).     

Co‐Culture of Keratinocyte‐Staphylococcus aureus on Cu‐Ag‐Zn/CuO and Cu‐Ag‐W Nanoparticle Loaded Bacterial Cellulose:PMMA Bandages

Pressurized gyration and its sister processes are novel methods to produce polymeric fibers. Potential applications for such fibers include wound dressings, tissue engineering scaffolds, and filters. This study reports on a pressurized gyration technique that employs pressured N₂ gas to prepare biocompatible wound dressing bandages from bacterial cellulose and poly (methylmethacrylate) polymer blended with alloyed antimicrobial nanoparticles. Resulting bandages are manufactured with high product yield and characterized for their chemical, physical, and mechanical properties. Increased density in solutions with additional antimicrobial nanoparticles results in increased fiber diameters. Also, addition of antimicrobial nanoparticles enhances ultimate tensile strength and Young's modulus of the bandages. Typical molecular bonding in the bandages is confirmed by Fourier‐transform infrared spectroscopy, with peaks that have higher intensity and narrowing points being caused by additional antimicrobial nanoparticles. More so, the cellular response to the bandages and the accompanying antimicrobial activity are studied in detail by in vitro co‐culture of Staphylococcus aureus and keratinocytes. Antimicrobial nanoparticle‐loaded bandage samples show increased cell viability and bacteria inhibition during co‐culture and are found to have a promising future as epidermal wound dressing materials.     

Classification of Kashar Cheeses Based on Their Chemical,Color and Instrumental Textural Characteristics Using Principal Component and Hierarchical Cluster Analysis

Principal component analysis and hierarchical cluster analysis were applied to investigate physicochemical and instrumental textural properties of fresh kashar cheese. Four different principal components sufficiently explained the variability in the cheese samples. In addition, hierarchical cluster analysis was performed to group the kashar cheese samples regarding physicochemical and instrumental textural properties. Instrumental textural properties indicated greater variability than chemical composition of cheese samples. Principal component analysis revealed that color parameters were positively correlated with textural and chemical parameters. The results of this study revealed that other parameters rather than chemical composition would be effective on the instrumental textural properties. It was proved that principal component analysis was a very effective statistical tool to determine quality of cheese samples. According to the principal component analysis and hierarchical cluster analysis results, the attributes defining the kashar cheese samples were determined to be primarily the texture profile analysis parameters.     

N-way planar high-power combiner design for RF power amplifiers

The complete design using a novel technique for an N-way planar high-power combiner is introduced for radio-frequency (RF) power amplifiers (PAs) at high-frequency (HF) range for the first time. On the basis of this design technique, a three-way planar combiner is simulated, designed and built on a ceramic-based material that allowed a surface-mount application. Design charts for a thermally reliable operation under high-power conditions are given. The simulated and measured results are compared and found to be very close. The design technique for planar combiners introduced here can be used for RF PAs to obtain power level in the several-kilowatt range in HF communication for industrial and military applications.     

Chemical vapor deposition of carbon on particulate TiO2 from CH4 and subsequent carbothermal reduction for the synthesis of nanocrystalline TiC powders

The present study aims to investigate chemical vapor deposition of carbon from CH₄ on TiO₂ particles and to establish optimal conditions for the synthesis of nanocrystalline TiC powders. Mass measurements, XRD, HR-TEM and SEM were used to characterize the products at various stages of the reactions. Oxide particles gained mass rapidly at 1300 K under CH₄ atmosphere and were coated with thin pyrolytic carbon layers of 10-20 nm. XRD analysis showed that the coated powders consisted of C, TiO₂ and titanium sub-oxides. The powders containing ∼33 ± 2 wt% carbon were used for the carbothermal reduction of TiO₂ to TiC at 1600-1800 K under Ar flow. Lattice constant and mass loss of the samples increased to the levels of TiC with temperature and time. Nearly pure TiC powders with a mean particle size of ∼125 nm were synthesized at 1750-1800 K within 30 min.     

Thermodynamic analysis and synthesis of porous Mo2C sponge by vapor-phase condensation and in situ carburization of MoO3

Spongy porous MoO₃ deposits were grown by vaporization, vapor-phase transportation and condensation of MoO₃ in Ar flow. It was observed that increased source temperature (≥1200 K) and temperature gradient (≥100 K/cm) favor the formation of spongy deposit owing to high supersaturation of the oxide vapor at ～900 K. Spongy Mo₂C deposits consisting of intermingled platelet crystals with thin walls were synthesized by in situ carburization of the condensed MoO₃ using 0.05–0.1 mol of CH₄ and 1 mol of H₂ at 900 K. Thermodynamic analysis in the Mo–O–C–H system was used as a guide to predict the conditions for the formation of Mo₂C from the MoO₃–CH₄–H₂ reactants at 900 K. X-ray diffraction analysis showed that the carburized deposits consisted of single phase Mo₂C, in agreement with the thermodynamic prediction. The equilibrium analysis was also used to reveal possible reaction pathways to Mo₂C formation from MoO₃–CH₄–H₂ reactants which yielded gaseous products of H₂O, CO₂, CO, C₂H₆ and C₂H₄.     

A mobile off-grid platform powered with photovoltaic/wind/battery/fuel cell hybrid power systems

Cross utilization of photovoltaic/wind/battery/fuel cell hybrid-power-system has been demonstrated to power an off-grid mobile living space. This concept shows that different renewable energy sources can be used simultaneously to power off-grid applications together with battery and hydrogen energy storage options. Photovoltaic (PV) and wind energy are used as primary sources and a fuel cell is used as backup power. A total of 2.7 kW energy production (wind and PV panels) along with 1.2 kW fuel cell power is supported with 17.2 kWh battery and 15 kWh hydrogen storage capacities. Supply/demand scenarios are prepared based on wind and solar data for Istanbul. Primary energy sources supply load and charge batteries. When there is energy excess, it is used to electrolyse water for hydrogen production, which in turn can either be used to power fuel cells or burnt as fuel by the hydrogen cooker. Power-to-gas and gas-to-power schemes are effectively utilized and shown in this study. Power demand by the installed equipment is supplied by batteries if no renewable energy is available. If there is high demand beyond battery capacity, fuel cell supplies energy in parallel. Automatic and manual controllable hydraulic systems are designed and installed to increase the photovoltaic efficiency by vertical axis control, to lift up & down wind turbine and to prevent vibrations on vehicle. Automatic control, data acquisition, monitoring, telemetry hardware and software are established. In order to increase public awareness of renewable energy sources and its applications, system has been demonstrated in various exhibitions, conferences, energy forums, universities, governmental and nongovernmental organizations in Turkey, Austria, United Arab Emirates and Romania.     

Electrochemical synthesis of poly(methylsilyne) and investigation of the effects of parameters on the synthesis

This study aims to synthesize poly(methylsilyne) by electrochemical reduction of methyltrichlorosilane at a constant potential of ?6 V, while investigating the effects of parameters such as the nature of the electrode, solvent and supporting electrolyte, the monomer/solvent ratio, and the reaction time on the properties of the products. The polymer was characterized by ¹H‐NMR (Proton Nuclear Magnetic Resonance Spectroscopy), FTIR (Fourier Transform Infrared Spectroscopy), UV‐Visible Spectroscopy, and TGA (Thermogravimetry Analysis). Copper (Cu) electrodes were used as stainless steel introduced impurities into the system. In an electrolytic media consisting of acetonitrile (AN), sodium dodecyl sulfate (SDS), and Cu electrodes, increasing the monomer/solvent ratio and the reaction time affected the system negatively based on the purity of poly(methylsilyne) in the final product. Reproducible results were only achieved in an electrolytic media containing 1,2‐dimethoxyethane (DME) and tetrabutylammonium perchlorate (TBAP). In this system, the purity of the products was less dependent on monomer/solvent ratio and reaction time. The color and the ¹H‐NMR, FTIR, and UV‐Visible spectra proved that the product is poly(methylsilyne). In addition, the significantly high‐average decomposition temperature obtained from TGA results revealed that the polymer is a good candidate as an additive for improving thermal stability and flame retardancy in thermoplastics. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010