Progress and challenges in sustainability,compatibility, and production of eco-composites: A state-of-art review

Owing to economic and environmental benefits, new generations of materials/commodities follow “from waste to wealth” strategy. Recently, there has been a huge upsurge in research on the development of eco-composites using recycled plastic polymers and agro-residues because the eco-composites satisfy the stringent environment regulations and are cost-effective. Herein, we present a detailed review on the potential use of several types of natural fillers as an efficient reinforcement for recycled plastic polymers. In particular, the characterization of different categories of eco-composites according to their morphological, physical, thermal, and mechanical properties is extensively reviewed and their results are analyzed, compared, and highlighted. Furthermore, a framework to produce functional eco-composites, which includes functionalization of ingredients, critical issues on microstructural parameters, processing, and fabrication methods, is outlined and supported with sufficient data from the literature. Finally, the review outlines the emerging challenges and future prospects of eco-composites to be addressed by interested researchers to bridge the gap between research and commercialization of such a class of material. Overall, the acquired knowledge will guide researchers, scientists, and manufacturers to plan, select, and develop various forms of eco-composites with enhanced properties and optimized production processes.     

Synthesis,photophysical properties,and application of optical brighteners based on stilbene-oxadiazole derivatives

A series of symmetrical optical brighteners based on stilbene-oxadiazole derivatives were prepared by the simple synthetic route of a condensation reaction between 4,4′-dicarboxystilbene and N,N′-carbonyldiimidazole reagent, forming stilbene 4,4′-ethene-1,2-diyldibenzohydrazide as a key intermediate. The obtained compounds were characterised by analysis of nuclear magnetic resonance, mass spectrometry, and elemental analysis data. The absorption maximum wavelength, fluorescence emission wavelength, and fluorescence quantum yield were measured in N,N-dimethylformamide solution at room temperature, and the fluorescence properties of the prepared compounds in the solid state were observed and measured. The compounds exhibited bluish and greenish fluorescence emission, with the fluorescence quantum yield in the range 0.2–0.8; the effects of substituents on the emission spectra of these compounds were interpreted. The prepared compounds were applied as optical brighteners to polyester and polyamide-6 fabrics at various concentrations, and their CIE whiteness index and fastness properties were studied.     

Water Demand Forecasting in Umm Al-Quwain (UAE) Using the IWR-MAIN Specify Forecasting Model

IWR-MAIN software is used in this paper to forecast water demand in the Emirate of Umm Al-Quwain (UAQ), located in the northern part of the United Arab Emirates (UAE), for the next twenty 5 years. Two different databases are used. The first one provides average yearly water consumptions since 1980, while the second provides more detailed monthly water consumptions from 2000. The correlation between three different independent variables and water consumption is studied. These variables are population of UAQ, average temperature, and average rainfall. Results show that population is the most significant variable that affects water consumption in Umm Al-Quwain. Several calibration simulations are performed and each simulation is divided into two periods. In the first period the software “Statistical Package for the Social Sciences” (SPSS) is used to determine the correlation coefficients between the independent variables and actual water consumptions. These coefficients are used in IWR-MAIN over the second period to calculate values of water demand which are compared against actual water consumptions. Model calibration indicates that starting the calibration in 1999 in database one and 2006 in database 2 minimizes differences between actual and simulated water demands. Therefore, these simulations were used as the bases for several forecasting scenarios of water demand in Umm Al-Quwain. Results of one of these scenarios show that 50% increase in water demand is expected by the year 2015 and double of the current demand will be needed before 2025. In another forecasting scenario, it was found that by considering the expected increase in the income level, the water demand will increase by 40% in one decade. A new technique of using IWR-MAIN to separate estimates of metered demand, unmetered demand, and unaccounted water (losses) is also presented in this paper. Finally, results of a fourth scenario indicate that water demand in Umm Al-Quwain will be highly affected by the expected high migration rate due to the anticipated new developments in the emirate.     

Analysis of cooling curve to determine the end point of freezing

The cooling curve method used for the measurement of freezing point of food is further analyzed to explore whether it can be used to identify the end point of freezing or glass transition. In this method, slope of the cooling curve is determined and plotted as a function of time to identify the end point of freezing (T′_m). Initially, the slope is decreased and then reached a minimum value, which is identified as the nucleation of ice. Then the slope is increased until the end point of freezing. The end point of freezing is identified when the slope starts to decrease from its highest value or plateau. Sucrose solutions and starch gels were used to measure its T′_m in identifying validity of the proposed method. The measured values of T′_m by the proposed method is very close to the literature values.     

Feasibility of using various photovoltaic systems for window-type air-conditioning units under hot-arid climates

This paper reports on the feasibility of using various Photovoltaic (PV) systems namely; Grid PV (GPV), Stand-Alone PV (SAPV), Grid PV Wind (GPVW) and PV Wind (PVW) for supplying the power requirements of a window-type air-conditioning system or other small loads. It was found that the GPVW system is the best system to meet the load requirement of a window-type air-conditioning system under the climatic conditions of Oman with values ranging from $39,500 to $56,500 for the capital cost and $9,000 to $33,000 for the total net capital cost depending on the wind speed. These values are attractive for remote off grid applications.     

A descriptive analysis of light vehicle-heavy vehicle interactions using in situ driving data

Two recently completed on-road in situ (naturalistic) data collection efforts provided a large data set in which to conduct an examination of crashes, near-crashes, and crash-relevant conflicts (referred to as critical incidents throughout this paper) that occurred between light vehicles (LV) and heavy vehicles (HV). Video and non-video data collected during the two studies were used to characterize critical incidents that were recorded between LV and HV drivers. Across both studies, 210 LV-HV critical incidents were recorded. Of these, 78% were initiated by LV drivers, while the remaining 22% were initiated by HV drivers. Aggressive driving, on the part of the LV driver, was found to be the primary Contributing Factor for LV driver-initiated incidents. For HV driver-initiated incidents, the primary Contributing Factor was poor driving techniques. These results suggest that future efforts at addressing LV-HV interaction incidents should include focusing on aggressive LV drivers. Additionally, it is recommended that HV drivers might benefit from improved driver training that includes instruction on defensive driving skills. The in situ methodology provides an alternative to traditional crash databases, developed from police accident reports, for studying crash causation and driver behavior.     

Quality of Processed Cheddar Cheese as a Function of Emulsifying Salt Replaced by κ-Carrageenan

Hydrocolloids act as stabilizer and thickening agents, thus able to replace emulsifying salts. The present study was planned to use к-carrageenan in the production of processed cheddar cheese and to explore its effect on physico-chemical and textural properties of processed cheddar cheeses. Different concentration of ?-carrageenan were used with gradual decrease in salt contents along with natural cheese, fat, and water to prepare processed cheddar cheese. The prepared samples were analyzed for physico-chemical and sensory attributes at storage interval of 45 days during and after 90 days. With the increase in hydrocolloid concentration, stiffer product was obtained and meltability of the samples decreased than control. Processed cheddar cheese samples having 0.15% к-carrageenan with 2% emulsifying salt (1.34% sodium citrate and 0.66% disodium phosphates) were found more acceptable in terms of physico-chemical and sensory attributes, but all sensory attributes got fewer score with the passage of storage time.     

Effects of heavy metals and polyelectrolytes in humic substance coagulation under saline conditions

Charge neutralisation plays a major role in heavy metal and humic substance removal in water treatment. Humic substances have no readily identifiable structure and they consist of anionic macromolecules of low to moderate molecular weight. Humic substances are easily coagulated using cationic metals and polyelectrolytes. Different concentrations of humic substances have been coagulated with different concentrations of heavy metals and/or polyelectrolytes. The charge neutralisation was determined using U.V. spectrophotometer. Humic substance removal increased with increasing salinity level until reaching a point where HS destabilization is considered complete and salinity no longer play a role in HS removal. Humic substance removal increased with increasing heavy metals concentration and precipitation was experienced at high concentrations of heavy metals (15–20 mg/L) and low concentration of humic substances (10 mg/L). In addition, HS removal also increased with increasing polyelectrolyte concentration. Diallydimethylammonium chloride (PDADMAC) polyelectrolyte was more effective in humic substance coagulation compared to copolymer of dimethyl aminoethyl acrylate (CoAA). The addition of heavy metals in polyelectrolyte coagulation increased humic substance removal due to the combined charge neutralization of the metals and polyelectrolytes.     

Constructal design of distributed energy systems: Solar power and water desalination

Here we show the fundamental tradeoffs that underpin the design of a distributed energy system with two objectives: the production and distribution of electric power driven by solar heating, and desalinated water produced by consuming solar power. We show analytically that larger solar power plants and desalination plants are more efficient than smaller plants. This phenomenon of economies of scale is countered by the greater losses associated with larger distribution networks. From this conflict emerges the proper allocation of nodes of production of power and water on a territory. We show that as the individual needs of power and water increase in time, the sizes of solar plants and desalination plants increase, and so does the size of the territory served by each power plant. At the same time, the territory served by each desalination plant decreases, and this means that the number of desalination plants allocated to one power plant increases.