In this work, anthocyanin stability and color of encapsulated freeze-dried saffron petal's extract with various matrices consisting gum Arabic (AG) and maltodextrin (M7 and M20) were studied. Total ...anthocyanins of powders and color parameters (a*, b*, L*, C, H° and TCD) were measured immediately after production and during storage up to 10 weeks by pH differential method and computer vision, respectively. Different compounds of wall materials did not show any significant differences in terms of stabilizing anthocyanins (P<0.01) and no significant decrease in anthocyanin content of the powders was observed after storage. The efficiency order of wall materials considering total color differences (TCD) was AG>M20>M7. By evaluating 3D surface and Cox trace plots it was revealed that wall formulas which had the lowest amount of AG and highest amounts of M20 and M7 showed the lowest total color differences after storage (P<0.05). To conclude, microencapsulation by freeze drying could be recommended as a suitable method for stabilizing anthocyanins of saffron petal's extract.
Oxygen-induced doping on reduced PEDOT Mitraka, E; Jafari, M J; Vagin, M ...
Journal of materials chemistry. A, Materials for energy and sustainability,
2017, Letnik:
5, Številka:
9
Journal Article
Recenzirano
Odprti dostop
The conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) has shown promise as air electrode in renewable energy technologies like metal-air batteries and fuel cells. PEDOT is based on atomic ...elements of high abundance and is synthesized at low temperature from solution. The mechanism of oxygen reduction reaction (ORR) over chemically polymerized PEDOT:Cl still remains controversial with eventual role of transition metal impurities. However, regardless of the mechanistic route, we here demonstrate yet another key active role of PEDOT in the ORR mechanism. Our study demonstrates the decoupling of conductivity (intrinsic property) from electrocatalysis (as an extrinsic phenomenon) yielding the evidence of doping of the polymer by oxygen during ORR. Hence, the PEDOT electrode is electrochemically reduced (undoped) in the voltage range of ORR regime, but O
keeps it conducting; ensuring PEDOT to act as an electrode for the ORR. The interaction of oxygen with the polymer electrode is investigated with a battery of spectroscopic techniques.
•An alternative heat source in remote area. Using the advantages of evaporative desalination instead of osmosis methods.•Suitable for coastal areas in the south of country which enjoys plenty of ...solar energy as a promising technology for meeting water demand.•Production lower levels of carbon dioxide.•Feed water conservation in MSFD type of Brackish water Desalination.
The scope of this article is to provide solutions for two famous bottlenecks against more popularity of Multi-Stage Flash Distillation application among the world; supply required heat specially in remote areas and high rate of feed water rejection. To overcome the first challenge, adequate combinations of technologies for the available 197ton/h MSFD unit in a case study plant and Direct Steam Generation (DSG) as an alternative renewable energy source are considered. The retrofit study on such plants may lead to achieve solar steam. Steam is used as heat source in the brine heater of Multi-Stage Flash Distillation unit. So, as the result of this modification, 17.8MW of fossil energy is replaced by solar energy. In the second place, returning of more than 50 percent of the treated water to the river with around 14°C temperature rise, by using cooling tower system, is prevented. It is revealed that for each of three existing thermal desalination plants up to 53 percent of feed water, i.e.; 667m3/h and same amount of reject water can be conserved. Though, with this modification, the unit steam consumption has been increased up to 13ton/h, about 50 percent of design value.
•We propose a model for forecasting cooling and electricity load demand.•The model takes the advantage of both time series and regression methods.•The model is able to accurately forecast the load ...demands of the CCHP system.
The objective of this paper is to extend a statistical approach to effectively provide look-ahead forecasts for cooling and electricity demand load. Our proposed model is a generalized form of a Cochrane–Orcutt estimation technique that combines a multiple linear regression model and a seasonal autoregressive moving average model. The proposed model is adaptive so that it updates forecast values every time that new information on cooling and electricity load is received. Therefore, the model can simultaneously take advantage of two statistical methods, time series, and linear regression in an adaptive way. The effectiveness of the proposed forecast model is shown through a use case. The example utilizes the proposed approach for economic dispatching of a combined cooling, heating and power (CCHP) plant at the University of California, Irvine. The results reveal the effectiveness of the proposed forecast model.
The wind-induced vibration of cables has been widely studied over the past decades because of cables’ many applications in cable-stayed, suspension, and tied-arched bridges, and power transmission ...lines. They have been mostly investigated through research conducted on rigid model cables with a finite length and circular cross-sectional geometry that represents a section model of a long cable. These models have been considered accurate because the behavior of flow over a cable and circular cylinder is similar, although there are structural differences between them. Cables usually experience small- to large-amplitude vibration due to wind loads that causes fatigue failure and poses a significant threat to the safety and serviceability of these structures. Although this paper mainly focuses on reviewing the past studies about different types of wind-induced cable vibration, some general information related to circular cylinders has been briefly reported for better understanding of the flow over cables. This paper incorporates an extensive review based on the existing papers about different sources of wind-induced cable vibration consisting of vortex-induced vibration, rain-wind-induced vibration, dry galloping, ice galloping, and wake galloping. Furthermore, this paper explains the mechanism, vibration source, and a mitigation solution for each type based on the past studies using wind tunnel experiments, computational fluid dynamics, field measurements, or analytical approaches. This review helps to better understand the aerodynamics and fluid–structure interactions of cables with or without ice/rain on the surface, while static and dynamic wind loads act on the structure.
► Caffeine and theophylline were analysed simultaneously. ► Ion mobility spectrometry as a rapid, sensitive and inexpensive method was used. ► Molecular imprinted polymer as a powerful method was ...used for extraction and cleanup. ► The analysis time was very shorter than that for commonly used methods.
In this work for the first time, simultaneous analysis of caffeine and theophylline was done by ion mobility spectrometry (IMS) only, without a powerful separation technique (e.g., HPLC). Ion mobility spectrometry with low cost, inexpensive maintenance and very fast analysis makes an attractive technique for the simultaneous determination of the caffeine and theophylline in foodstuff samples and biological matrices. In this study, the extraction protocol using molecular imprinted polymer-solid phase extraction (MIP-SPE) was successfully used to directly extract caffeine and theophylline from real samples. The results obtained provided the detection limits of 0.2 and 0.3μgmL−1 for caffeine and theophylline, respectively. The linear dynamic range of about two orders of magnitude was obtained for these compounds. Also, the proposed method was used to analyse various real samples of green tea and spiked human plasma, and the obtained results confirmed the capability of ESI-IMS for simultaneous detection of caffeine and theophylline.
A new wideband microstrip antenna, based on the falcate‐shaped patch, with reconfigurable capability at circular‐polarization is presented in this article. To achieve both properties of stable ...radiation characteristics and impedance matching across a broad bandwidth, the combination of the L‐probe feeding and falcate‐shaped patch is used. An RF‐switch is utilized to excite the L‐probes and generate either left‐hand circular polarization or right‐hand circular polarization over the wide operating bandwidth. A prototype of the proposed antenna is fabricated. An excellent agreement exists between the simulation and measurement results. The results reveal a wide impedance matching (|S11| < − 10 dB), bandwidth of 55% (1.42‐2.5 GHz), and a 3 dB axial ratio bandwidth of 44% (1.6‐2.5 GHz). Furthermore, results confirm good radiation and impedance matching performance of the fabricated antenna over the wide bandwidth in comparison with previous related investigations. The reported reconfigurable antenna can be used as a suitable choice for GPS, ISM band, or RFID applications
•Comparative technoeconomics of ceramic and polymeric membrane technologies assessed.•Bench-scale tests show no consistent difference in permeability between two membranes.•Polymeric membranes ...subject to mechanical strength and permeability decline with age.•Membrane deterioration from hypochlorite cleanant specific to polymeric membranes.•Robustness of ceramic membranes permits more aggressive/effective chemical cleaning.
The continued technological developments and decreased purchase costs of ceramic membranes have seen increased recent interest in the technology as an alternative to the more widely used polymeric membranes. This paper assesses the relative technical, practical and economic merits of the two membrane materials in the context of potable water production from surface water sources.
The work focuses on phenomena of direct technoeconomic significance, namely cleaning efficacy (manifested as permeability recovery), membrane integrity and incurred labour effort. Topics reviewed thus comprise: (a) practical comparison of the two technologies challenged with the same feedwater, (b) comparative technoeconomic analyses, (c) membrane integrity studies of polymeric membranes - incorporating aged samples extracted from operating installations, (d) sludging incidents, and (e) pilot and full-scale data.
Available relevant data reveal:
(a) bench-scale comparative tests do not indicate a consistent significant difference in the net permeability between the two membranes;
(b) polymeric membranes are subject to a decline in both mechanical strength and permeability from the loss of the hydrophilic agent over a period of years from the action of hypochlorite used for cleaning;
(c) the decreased mechanical strength with age of polymeric membranes increases the manual repair requirement and shortens membrane life, respectively impacting on labour and membrane replacement costs where the latter is also determined by the permeability;
(d) the chemical and mechanical robustness of ceramic membranes permits more aggressive chemical cleaning, which then affects the chemicals consumption cost; and
(e) anecdotal evidence suggests that polymeric membranes challenged with pre-coagulated surface waters may be subject to sludging, the agglomeration of solids in the membrane channels, which may also be age-related.
Notwithstanding the above, data from published comparative technoeconomic studies indicate a linear relationship between the overall cost benefit and the membrane module cost ratio mitigated by the relative membrane life and operating flux.
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In this study, effective thermal conductivity and viscosity of multi walled carbon nanotubes water based nanofluids containing multi walled carbon nanotubes with various geometrical characteristics ...were investigated, with volume fraction 0.05 vol%. The experimental results demonstrated that thermophysical properties of the nanofluids depend on the geometrical characteristics of carbon nanotubes. The results were compared with some well-known models for thermal conductivity enhancement and relative viscosity and good conformities were observed. In this research, maximum enhancements of 36% and 5.5% were achieved for nanofluids effective thermal conductivity and dynamic viscosity respectively; these improvements were established in comparison to the base fluid at 45 °C. In addition, the results indicate that applying processes based on the surface modification on the nanotubes and improvement in nanoparticles dispersion can lead to enhancement in thermophysical properties in the nanofluids. During the experiments, the effective procedure of nanofluids stabilization was obtained. These findings combined with obtaining a pH value near the neutral state result an improvement in heat transfer and flow characteristics of the nanofluids.
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•Research on Carboxyl-multi walled carbon nanotubes aqueous nanofluids•Utilization of a binary surfactants mixture to the dispersion in the base fluid•Obtaining stable multi walled carbon nanofluids with pH values close to neutral•Observing Newtonian behavior in Carboxyl-multi walled carbon nanofluids
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