Antioxidant,antifungal, water binding,and mechanical properties of poly(vinyl alcohol) film incorporated with essential oil as a potential wound dressing material

In this study, the properties of poly (vinyl alcohol) (PVA) films incorporated with Zataria multiflora essential oil (ZMO) as a potential antioxidant/antibacterial material was investigated. PVA films were prepared from PVA solutions (2% w/v) containing different concentrations of ZMO. Water solubility, moisture absorption, water swelling, and water vapor permeability for pure PVA films were 57 ± 1.1, 99 ± 3.2%, 337 ± 8%, and 0.453 ± 0.015 g mm/m² h, respectively. Incorporation of ZMO into PVA films caused a significant decrease in water swelling and moisture absorption and increase in solubility and water vapor permeability. Tensile strength, elastic modulus, and elongation at break for pure PVA films were 13.5 ± 0.61 MPa, 15.2 ± 0.8 MPa, and 216 ± 4%, respectively. Incorporation of ZMO into the PVA films caused a significant decrease in tensile strength and elastic modulus and increase in elongation at break of the films. Pure PVA film showed UV‐visible light absorbance ranging from 280 to 440 nm with maximum absorbance at 320 nm. Addition of ZMO caused a significant increase in light absorbance and opacity. PVA films exhibited no antioxidant and antifungal activities, whereas PVA/ZMO films exhibited excellent antioxidant and antifungal properties. Although the bioactivity PVA films were improved by the addition of ZMO, however, the mechanical properties and water binding capacity of the films were weaken slightly. Thus, ZMO emulsified in the ethanol not compatible with PVA matrix and more suitable emulsifier was needed in order to obtain strong film with higher mechanical properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40937.     

Environmental impacts of desalination on the ecology of Lake Urmia

Lake Urmia, the second largest hypersaline lake by area in the world, has fluctuated in salinity over time, but in recent years, it has reached a maximum of 340 g/L. The lake is the main habitat for the endemic Iranian brine shrimp, Artemia urmiana, and is a protected aquatic environment. Efforts have been made by the Iranian government to enhance the diversity of its wildlife. One approach has been to look for a method to reduce the salt content of the lake. We investigate the feasibility of this by first considering the water chemistry of Lake Urmia and then the various technologies used to extract salt from marine and brackish waters. Average concentrations of Na, Mg, K, Ca, Cl, SO₄, and HCO₃ were 125 g/L, 11.3 g/L, 2.63 g/L, 0.55 g/L, 216 g/L, 22.4 g/L, and 1.38 g/L, respectively, and cations and anions were balanced, However, Lake Urmia waters have a ‘very high’ salinity hazard and a high sodium adsorption ratio (SAR). Moreover, the saturation index (SI) for each of the major cations was greater than zero, indicating that the water in Lake Urmia is supersaturated, and precipitation is likely. The extraction of available salts from the lake for the use in petrochemical industries is economically feasible. However, technologies based on removing salts by distillation or reverse osmosis and then using this fresh water to dilute lake salinity are problematic. A better strategy would be better to allow more fresh water to reach the lake rather than creating fresh water through reverse osmosis and distillations processes. While concerns have been raised about the salinity tolerance of A.urmiana, it has successfully tolerated various salinity ranges from 166 to 340 g/L, and so the species is not threatened, unless the lake desiccates. Because the lake is saturated with salts, it seems unlikely that salinity could increase much higher.     

Enhanced removal of benzene in nonthermal plasma with ozonation,flow recycling,and flow recirculation

A double stage AC/DC sequential high voltage reactor has been developed to study the decomposition of benzene in the air stream at atmospheric pressure. The removal efficiency was measured as a function of ozonation, flow recycling, and flow recirculation. Ozonation in the inlet, and recycling of the exhaust stream increased the removal of benzene, also with increasing of specific input energy (J l⁻¹) the effect of inlet flow ozonation on benzene decomposition was enhanced. The highest removal efficiency was obtained up to >99% in recirculation six times, while CO₂ selectivity reached 99.9% and energy efficiency was 0.59 g kWh⁻¹. O₃ production/ decomposition > production of OH radicals > electronic and ionic collisions were indicated as the main mechanisms influencing benzene abatement in this research.     

Preparation and photocatalytic study of CoFe2O4/TiO2/Au nanocomposites and their applications in organic pollutant degradation and modeling by an artificial neural network (ANN)

Journal of Materials Science: Materials in Electronics - Due to the increase of environmental pollution by various industries in recent decades, preparing drinking water has become one of the most...     

Modeling triplet spike-timing-dependent plasticity using memristive devices

Triplet-based spike-timing-dependent plasticity (TSTDP) is an advanced synaptic plasticity rule that results in improved learning capability compared to the conventional pair-based STDP (PSTDP). The TSTDP rule can reproduce the results of many electrophysiological experiments, where the PSTDP fails. This paper proposes a novel memristive circuit that implements the TSTDP rule. The proposed circuit is designed using three voltage (flux)-driven memristors. Simulation results demonstrate that our memristive circuit induces synaptic weight changes that arise due to the timing differences among pairs and triplets of spikes. The presented memristive design is an initial step toward developing asynchronous TSTDP learning architectures using memristive devices. These architectures may facilitate the implementation of advanced large-scale neuromorphic systems with applications in real-world engineering tasks such as pattern classification.     

Analysis of DLL Jitter due to Voltage-Controlled Delay Line

In this paper we analyze jitter in a delay-locked loop (DLL) due to uncertainties in the voltage-controlled delay line (VCDL). To obtain a closed-form equation for jitter in the DLL, time-domain equations of the DLL are used. The jitter at the intermediate stages of the VCDL and the jitter of a conventional delay cell are analyzed. The simulation results show that the jitter of the DLL due to mismatch of the delay cells is zero at the beginning and end of the VCDL and is highest at the middle of the VCDL. Also, a DLL is designed in TSMC 0.18 μm CMOS technology to show the accuracy of the proposed analytical method.     

Capillary Pressure Estimation Using Statistical Pore Size Functions

Capillary pressure curves, which have been employed for a long period of time by researchers interested in pore size distribution, are commonly obtained from experimental measurements. The dynamic capillary pressure that influences the flow is affected by many factors including the pore size characteristics and pore scale dynamics. Hence, it is important to investigate the variation of the estimated pore size distribution with capillary number. In this study, a glass type micromodel is considered as the porous media sample. A parametric probability density function is proposed to express the pore size distribution of the porous model, which is also measured using an image analysis technique. The capillary pressure saturation mathematical model is developed by integrating the pore size distribution function. Model parameters with a physical significance are estimated by fitting the model to the measured capillary pressure data at different capillary numbers. The results of capillary pressure obtained are well matched to the measured values. The results show that the trends of the extracted pore size distribution curves have similar trends, but they are not exactly the same. Therefore, the dynamic capillary pressure data alone are not sufficient for estimation of the pore size distribution. As a related development, the prediction of the capillary pressure curves based on measured pore size distributions is also presented. The proposed probability distribution function has the flexibility of representing a wide variety of pore size distributions.     

Identifying cost-optimal options for a typical residential nearly zero energy building’s design in developing countries

Clean Technologies and Environmental Policy - High population growth rate and the limited non-renewable energy sources such as fossil fuels have made different challenges for the energy supply in...     

Perceived demands and musculoskeletal symptoms among employees of an Iranian petrochemical industry

As a part of a comprehensive ergonomics program, this study was conducted among employees of an Iranian petrochemical industry to determine the prevalence of musculoskeletal symptoms and to examine the relationship between perceived demands and reported symptoms. In this cross-sectional study, 928 randomly selected employees, corresponding to nearly 40% of all employees participated. Nordic Musculoskeletal Disorder Questionnaire and Job Content Questionnaire were used as collecting data tools. The results showed that 73% of the study population had experienced some form of symptoms from the musculoskeletal system during the last 12 months. Knees and lower back symptoms were the most prevalent problem among the employees studied. The results revealed that perceived physical demands were significantly associated with musculoskeletal symptoms (OR ranged from 1.45 to 2.33). Among the perceived physical demands, awkward working postures were most frequently associated with reported musculoskeletal symptoms. Association was also found between perceived psychological demands and reported symptoms. Conflicting demands, waiting on work from other people or departments, interruption that other make, working very fast and time pressure were psychological factors retained in the regression models with OR ≥ 1.49. Based on the findings, it could be concluded that any interventional program for preventing or reducing musculoskeletal symptoms among the petrochemical employees studied had to focus on reducing physical demands, particularly awkward working postures as well as psychological aspect of working environment.

Relevance to industry

In petrochemical industry where employees are involved in both static and dynamic activities, determination of musculoskeletal symptoms contributing factors can be considered as a basis for planning and implementing interventional ergonomics program for preventing musculoskeletal symptoms and improving working conditions.