A preliminary investigation of caramelisation and isomerisation of allulose at medium temperatures and alkaline pHs: a comparison study with other monosaccharides

Allulose, also known as rare sugar, is a very reactive monosaccharide in browning reactions. In this study, the caramelisation of allulose was investigated for the first time. To study caramelisation, sugar solutions (glucose, fructose and allulose) were prepared with distilled water and buffer solutions at pH 7, 10, 12 and were freeze-dried afterwards. To let caramelisation occur, samples were incubated at 55% relative humidity (RH) and 50 °C. Results showed that samples prepared with pH 10 and pH 12 buffer solutions resulted in a higher browning rate than samples prepared with distilled water (DW) and pH 7 buffer solution. Moreover, according to HPLC and total reducing sugar content results, allulose (Allu) samples had the lowest remaining reducing sugar (RRS) amount, indicating that Allu samples depleted more in the reaction. Overall, the approach followed in this study can be considered as a novel strategy to obtain allulose-containing caramel-like products more efficiently than conventional methods.     

Synthesis and characterization of conducting copolymer of Trans‐1‐(4‐methyl‐3′‐thienyl)‐2‐(ferrocenyl)ethene with EDOT

Ferrocene‐substituted conducting polymer namely poly(trans‐1‐(4‐methyl‐3′‐thienyl)‐2‐(ferrocenyl)ethene‐co‐3,4‐ethylenedioxythiophene) [P(MTFE‐co‐EDOT)] was synthesized and its electrochromic properties were studied. Monomer, MTFE, was obtained using 2‐(ferrocenyl)ethene and 3‐methyl‐4‐bromothiophene. The structure of monomer was determined via Fourier transform infrared spectroscopy (FTIR), ¹H‐NMR, and ¹³C‐NMR techniques. The copolymer was synthesized using this monomer and EDOT. The resulting copolymer P(MTFE‐co‐EDOT) was characterized by cyclic voltammetry, FTIR, scanning electron microscopy, atomic force microscopy, and UV–vis spectroscopy. The conductivity measurements of copolymer and PEDOT were accomplished by the four‐probe technique. Although poly(trans‐1‐(4‐methyl‐3′‐thienyl)‐2‐(ferrocenyl)ethene) [P(MTFE)] reveals no electrochromic activity, its copolymer with EDOT has two different colors (violet and gray). Band gap (E_g) and λ_max of P(MTFE‐co‐EDOT) were determined. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Graphene-enabled silver nanoantenna sensors

Silver is the ideal material for plasmonics because of its low loss at optical frequencies but is often replaced by a more lossy metal, gold. This is because of silver's tendency to tarnish and roughen, forming Ag(2)S on its surface, dramatically diminishing optical properties and rendering it unreliable for applications. By passivating the surface of silver nanostructures with monolayer graphene, atmospheric sulfur containing compounds are unable to penetrate the graphene to degrade the surface of the silver. Preventing this sulfidation eliminates the increased material damping and scattering losses originating from the unintentional Ag(2)S layer. Because it is atomically thin, graphene does not interfere with the ability of localized surface plasmons to interact with the environment in sensing applications. Furthermore, after 30 days graphene-passivated silver (Ag-Gr) nanoantennas exhibit a 2600% higher sensitivity over that of bare Ag nanoantennas and 2 orders of magnitude improvement in peak width endurance. By employing graphene in this manner, the excellent optical properties and large spectral range of silver can be functionally utilized in a variety of nanoscale plasmonic devices and applications.     

An enhanced damage plasticity model for predicting the cyclic behavior of plain concrete under multiaxial loading conditions

Some of the current concrete damage plasticity models in the literature employ a single damage variable for both the tension and compression regimes, while a few more advanced models employ two damage variables. Models with a single variable have an inherent difficulty in accounting for the damage accrued due to tensile and compressive actions in appropriately different manners, and their mutual dependencies. In the current models that adopt two damage variables, the independence of these damage variables during cyclic loading results in the failure to capture the effects of tensile damage on the compressive behavior of concrete and vice-versa. This study presents a cyclic model established by extending an existing monotonic constitutive model. The model describes the cyclic behavior of concrete under multiaxial loading conditions and considers the influence of tensile/compressive damage on the compressive/tensile response. The proposed model, dubbed the enhanced concrete damage plasticity model (ECDPM), is an extension of an existing model that combines the theories of classical plasticity and continuum damage mechanics. Unlike most prior studies on models in the same category, the performance of the proposed ECDPM is evaluated using experimental data on concrete specimens at the material level obtained under cyclic multiaxial loading conditions including uniaxial tension and confined compression. The performance of the model is observed to be satisfactory. Furthermore, the superiority of ECDPM over three previously proposed constitutive models is demonstrated through comparisons with the results of a uniaxial tension-compression test and a virtual test.     

Investigation of inverterless control of interior permanent-magnet alternators

This paper investigates the performance and control of a low-cost 6-kW concept demonstrator of an "inverterless" automotive alternator. This is based on a switched-mode rectifier (SMR) combined with a high-flux interior permanent-magnet (PM) machine. Duty cycle control of the SMR is described and the theoretical predictions are compared with open-loop experimental results. The efficiency of the concept demonstrator is examined as a function of speed and load. Control issues regarding automotive operation are discussed.     

Modeling of MOSFET parasitic capacitances, and their impact on circuit performance

We study layout dependent, parasitic capacitance contributions of MOSFETs with 3D simulations, and show that these contributions are for narrow and short devices comparable to intrinsic contributions. The performance of 65-nm technology is strongly affected by these components, and should therefore be modeled accurately in circuit simulations. We propose a methodology how to accurately and consistently model them in a design flow. The methodology is validated with ring oscillator measurements.     

Permittivity determination of liquid materials using waveguide measurements for industrial applications

There is a need for a simple and relatively inexpensive microwave method for complex permittivity, ?, determination of liquid materials in industrial applications. Measurement cables that connect the measurement cell to the measuring instrument (usually a vector network analyser) may be either subject to severe phase instability particularly if they are long or metrology-grade cables are not available, or subject to thermal variation. In these instances, calibration techniques based on complex scattering parameter measurements may drastically suffer from extension of the reference plane to the boundaries of the measurement cell or sample end surfaces. In such situations, amplitude-only methods based on simplified calibration techniques such as response calibration are appropriate and very feasible. These methods have applications in industry such as thickness measurement and disbonding and delamination detection. The motivation of this study is to investigate a suitable method for ? determination of liquid materials using amplitude-only waveguide measurements. The analysis is restricted to lossy dielectric materials, which possess large enough attenuation such that the multiple reflections between their two end surfaces can be neglected. We derived an equation in terms of the loss tangent of these materials for selecting a suitable material thickness. We presented two approximations (frequency-independent and power-series representation) for ? determination of these materials. For validation of the method, we measured the ? of methanol and commercially available antifreeze solution by our method using a simple (frequency response) calibration and by another waveguide method using the thru-reflect-line calibration.     

Composition and thermal properties of cattle fats

The physical‐chemical properties, fatty acid composition and thermal properties of cattle subcutaneous, tallow and intestinal fats were determined. Subcutaneous fat differed from the other fat types with respect to its lower melting point (29.0 °C) and higher saponification (211.4 mg KOH/g) and iodine (50.55) values. The cattle fat types contained palmitic acid (16:0), stearic acid (18:0), oleic acid (18:1n‐9) and linoleic acid (18:2n‐6) as the major components of fatty acid composition (24.58–25.90%, 10.21–33.33%, 28.18–46.05%, 1.54–1.73%, respectively). A differential scanning calorimetry (DSC) study revealed that two characteristic peaks were detected in both crystallization and melting curves. Major peaks (T_peak) of tallow and intestinal fats were similar and determined as 24.10–27.71 °C and 2.16–4.75 °C, respectively, for crystallization peaks and 7.09–9.39 °C and 43.28–46.49 °C, respectively, for melting peaks in DSC curves; however, those of subcutaneous fat (12.48 °C and –6.79 °C for crystallization peaks and 3.56 °C and 23.55 °C for melting peaks) differed remarkably from those of the other fat types.     

Changes in myofibrillar proteins during processing of pastirma (Turkish dry meat product) produced with commercial starter cultures

The effects of different commercial starter cultures (Staphylococcus carnosus, S. carnosus + Lactobacillus pentosus and Staphylococcus xylosus + Lactobacillus sakei), on myofibrillar proteins were investigated using differential scanning calorimetry (DSC) during the processing of pastirma. The stage of pastirma production significantly decreased the thermal stabilities of myosin and actin. Actin was less affected than myosin. The myofibrillar fraction of pastirma was hardly denaturated by S. carnosus, but more pronounced denaturation was obtained with S. carnosus + L. pentosus.