Polycyclic aromatic hydrocarbons (PAHs) in ambient particulate matter contribute considerably to human health risk. Simultaneous sampling of ambient PM2.5/PM10 was done to analyze the Ʃ16PAH across ...the four seasons of 2017 in Islamabad, Pakistan. The average Ʃ16PAH concentrations in PM2.5 and PM10 were 25.69 and 40.69 ng m−3, respectively. For both PM2.5 and PM10, the highest PAHs concentration was in winter (45.14, 67.10 ng m−3), while the lowest was in summer (16.40, 28.18 ng m−3). Source appointment indicated that vehicular exhaust, i.e., diesel, gasoline and alternatively fuel liquid natural gas (LNG), and compressed natural gas (CNG) combustion was the primary PAHs contributor, whereas biomass burning and fuel combustion (coal, biomass, wood, CNG) from stationary sources were another important sources. Health risk assessment showed that the lifetime cancer risk (LCR) values of PAHs were higher than the acceptable level in all four seasons. LCR values were the highest in winter (9.23 × 10−4 for PAHs in PM2.5 and 13.98 × 10−4 for PAHs in PM10) which were 9 and 13 times higher than tolerable cancer risk level respectively, and they were 2–3 times higher than the acceptable values in other seasons.
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•PM2.5/PM10 bound PAHs across four seasons in Islamabad are studied.•PAHs concentrations were the highest in winter, and the lowest in summer.•Vehicle emission was the dominant source of PAHs.•Lifetime cancer risk of PAHs were > the acceptable level across four seasons.
Development of textile materials with tailored properties by coating with nano-materials is an emerging field of research. The preparation and characterization of photoactive cotton fabric for UV ...protection and self-cleaning properties are reported herein. In this study, a photoactive sol comprising of a reactive blue dye, C.I. Reactive Blue 21 (RB-21), and TiO
2
was prepared by using sol gel method. The TiO
2
nano sol was mixed with RB-21 to extend its photocatalytic activity in the visible region of the solar spectrum. The cotton fabric was coated with the RB-21/TiO
2
sol
via
dip-pad-dry-cure method. Surface characterization of the coated cotton fabric was performed by FTIR-ATR, UV-visible absorption, XRD and SEM studies. FTIR-ATR and UV-visible spectra confirmed stable attachment of the photoactive RB-21/TiO
2
coating on the cotton fabric. SEM images and XRD pattern shown the presence of anatase TiO
2
on the coated cotton fabric. UV-protection, photocatalytic performance and self-cleaning properties of the coated cotton fabric were evaluated by the UV transmittance spectra, degradation of Rhodamine B (RhB) dye and stain removal under visible light respectively. Degradation of RhB was observed in the presence of RB-21/TiO
2
coated cotton when exposed to visible light. Moreover, the coated cotton fabrics displayed excellent UV protection properties.
Development of textile materials with tailored properties by coating with nano-materials is an emerging field of research.
Polyesters are thermoplastic polymers having ester functionalities in the backbone. Research on polyesters have led to the formation of nanocomposites with various nanoparticles including the carbon ...nanoforms. High-tech polyester nanocomposites have been applied in wide raging fields of electronics, space, automotives, biomedical, and other applied sectors. Among smart materials, stimuli responsive polymers and nanocomposites have been found to encompass broad span of technical fields. This ground-breaking review has been designed to present state-of-the-art ofshape memory polyester/nanocarbon nanocomposites. In this context, essential polymers explored so far include poly(lactic acid), polycarbonate, and others. Among nanofiller, fullerene, graphene, and carbon nanotube have been focused to study polyester/nanocarbon systems. In this context, the shape memory polyester nanomaterials of graphene,carbon nanotube, and fullerene have been developed. Fullerene nanofiller filled shape memory polyesters were mostly processed through solution, in situ and melt routes. Poly(lactic acid)/fullerene systems revealed electroactive shape memory effect with very low recovery time < 10s. Stimuli responsive polyester with graphene nanofiller were mostly solution processed. The thermo-responsive polyester/graphene nanocomposite had shape fixity 90-99%, whereas shape recovery of up to 100%. Carbon nanotube in shape memory polyesters may lead to electric actuations in 20-40 V, recovery ratio of 80-100%, shape fixity 80-90%, and low shape recovery time 5-15 s. By changing the type of nanocarbon, loading level, and polyester backbone, shape recovery response and ratio were considerably affected. These nanocomposites have exposed active responses toward heat, voltage, light, mechanical, and electrical impacts. For future advancement in this field, novel nanostructural design, combinations, fabrication, interactions, and shape memory mechanisms need to be investigated comprehensively.
Electromagnetic interference disturbs the working of electronic devices and affects the surroundings and human health. Consequently, research has led to the development of radiation-protection ...materials. Inherently conducting polymers have been found to be suitable for electromagnetic interference (EMI) shielding owing to their fine electrical conductivity properties. Moreover, nanoparticle-reinforced conjugated polymers have been used to form efficient nanocomposites for EMI shielding. Nanoparticle addition has further enhanced the radiation protection capability of conducting polymers. This state-of-the-art comprehensive review describes the potential of conducting polymer nanocomposites for EMI shielding. Conducting polymers, such as polyaniline, polypyrrole, and polythiophene, have been widely used to form nanocomposites with carbon, metal, and inorganic nanoparticles. The EMI shielding effectiveness of conducting polymers and nanocomposites has been the focus of researchers. Moreover, the microscopic, mechanical, thermal, magnetic, electrical, dielectric, and permittivity properties of nanocomposites have been explored. Electrically conducting materials achieve high EMI shielding by absorbing and/or dissipating the electromagnetic field. The future of these nanomaterials relies on nanomaterial design, facile processing, and overcoming dispersion and processing challenges in this field.
Polymeric nanofibers have emerged as exclusive one-dimensional nanomaterials. Various polymeric nanofibers and nanocomposite nanofibers have been processed using the thermoplastic, conducting, and ...thermoset matrices. This review aims to highlight the worth of electrospinning technology for the processing of polymer/nanocarbon nanocomposite nanofibers. In this regard, the design, morphology, physical properties, and applications of the nanofibers were explored. The electrospun polymer/nanocarbon nanofibers have a large surface area and fine fiber orientation, alignment, and morphology. The fiber processing technique and parameters were found to affect the nanofiber morphology, diameter, and essential physical features such as electrical conductivity, mechanical properties, thermal stability, etc. The polymer nanocomposites with nanocarbon nanofillers (carbon nanotube, graphene, fullerene, etc.) were processed into high-performance nanofibers. Successively, the electrospun nanocomposite nanofibers were found to be useful for photovoltaics, supercapacitors, radiation shielding, and biomedical applications (tissue engineering, antimicrobials, etc.).
Soil with heavy metals contamination, mainly lead (Pb), cadmium (Cd), and chromium (Cr) is a progressively worldwide alarming environmental problem. Recently, biochar has been used as a soil ...amendment to remediate contaminated soils, but little work has been done to compare with other organic amendments like compost. We investigated biochar and compost's comparative effect on Pb, Cd, and Cr immobilization in soil, photosynthesis, and growth of maize plants. Ten kg soil was placed in pots and were spiked with Pb, Cd, and Cr at concentrations 20, 10, 20 mg kg
. The biochar and compost treatments included 0, 0.5, 1, 2, and 4% were separately applied to the soil. The crop from pots was harvested after 60 days. The results show that the highest reduction of AB-DTPA extractable Pb, Cd, and Cr in soil was 79%, 61% and 78% with 4% biochar, followed by 61%, 43% and 60% with 4% compost compared to the control, respectively. Similarly, the highest reduction in shoot Pb, Cd, and Cr concentration was 71%, 63% and 78%with 4% biochar, followed by 50%, 50% and 71% with 4% compost than the control, respectively. The maximum increase in shoot and dry root weight, total chlorophyll contents, and gas exchange characteristics were recorded with 4% biochar, followed by 4% compost than the control. The maximum increase in soil organic matter and total nitrogen (N) was recorded at 4% biochar application while available phosphorus and potassium in the soil at 4% compost application. It is concluded that both biochar and compost decreased heavy metals availability in the soil, reducing toxicity in the plant. However, biochar was most effective in reducing heavy metals content in soil and plant compared to compost. In the future, more low-cost, eco-friendly soil remediation methods should be developed for better soil health and plant productivity.
Abstract
In this study, we explored the role of biochar (BC) and/or urease inhibitor (UI) in mitigating ammonia (NH
3
) and nitrous oxide (N
2
O) discharge from urea fertilized wheat cultivated ...fields in Pakistan (34.01°N, 71.71°E). The experiment included five treatments control, urea (150 kg N ha
−1
), BC (10 Mg ha
−1
), urea + BC and urea + BC + UI (1 L ton
−1
), which were all repeated four times and were carried out in a randomized complete block design. Urea supplementation along with BC and BC + UI reduced soil NH
3
emissions by 27% and 69%, respectively, compared to sole urea application. Nitrous oxide emissions from urea fertilized plots were also reduced by 24% and 53% applying BC and BC + UI, respectively, compared to urea alone. Application of BC with urea improved the grain yield, shoot biomass, and total N uptake of wheat by 13%, 24%, and 12%, respectively, compared to urea alone. Moreover, UI further promoted biomass and grain yield, and N assimilation in wheat by 38%, 22% and 27%, respectively, over sole urea application. In conclusion, application of BC and/or UI can mitigate NH
3
and N
2
O emissions from urea fertilized soil, improve N use efficiency (NUE) and overall crop productivity.
Carbon fibers have been technically applied in high performance materials and industrial scale applications. Importantly, carbon fiber reinforced composite materials have found applications in ...aerospace industries. These properties of carbon fiber reinforced composites depend upon the carbon fiber features such as length, orientation, surface properties, adhesion with matrices, etc. To improve the surface properties of carbon fibers and adhesion and interactions with polymers, fiber modification has been suggested as an efficient approach. Carbon nanoparticle or nanocarbon functionalized carbon fibers have been manufactured using various facile physical and chemical approaches such as electrospraying, electrophoretic deposition, chemical vapor deposition, etc. Consequently, the modified carbon fibers have nanocarbon nanoparticles such as graphene, carbon nanotube, nanodiamond, fullerene, and other nanocarbons deposited on the fiber surface. These nanocarbon nanoparticles have fine capability to improve interfacial linking of carbon fibers with the polymer matrices. The chemical vapor deposition has been adopted for uniform deposition of nanocarbon on carbon fibers and chemical methods involving physical or chemical modification have also been frequently used. The resulting advanced epoxy/carbon fiber/nanocarbon composites revealed improved tensile and physical profiles. This review basically aims manufacturing and technical aspects of polymer/fiber/nanofiller nanocomposites toward the development of high performance structures. The resulting morphology, strength, modulus, toughness, thermal stability, and other physical features of the nanocarbon functionalized carbon fibers have been enhanced. In addition, the fabricated polymer/fiber/nanofiller nanocomposites have fine interfacial adhesion, matrix-nanofiller-filler compatibility, and other characteristics. The application areas of these nanomaterials have been found wide ranging including the strengthened engineering structures, supercapacitors, shape memory materials, and several others.
Carbonaceous or nanocarbon nano-reinforcement nanocomposites have been found as emergent candidates for aerospace industry. Consequently, the multifunctional nanocomposites have been fabricated using ...marvelous nanocarbon nanostructures like graphene, carbon nanotube, fullerene, carbon black, etc. Manufacturing techniques have also been engrossed for the formation of high performance engineering nanocomposites having fine strength, heat stability, flame resistance, and other space desired features. These practices include solution, in situ, and melt procedures, on top of specific space structural design techniques, for the formation of aerospace structures. The aerospace related material property enhancements using various carbonaceous nano-reinforcements depends upon the type of nanocarbon, dimensionality, as well as inherent features of these nanostructures (in addition to the choice of manufacturing methods). Furthermore, carbon nano-reinforcements have been filled, besides carbon fibers, in the epoxy matrices. Nanocarbon coated carbon fibers have been filled in epoxy resins to form the high performance nanomaterials for space structures. The engineering features of these materials have been experiential appropriate for the aerospace structures. Further research on these nanomaterials may be a key towards future opportunities in the aero systems. Additionally, the explorations on structure-property relationships of the carbonaceous nanocomposites have been found indispensable for the development of advanced aerospace structures.
Herein, we report the green synthesis of silver nanoparticles (OE-Ag NPs) by ecofriendly green processes using biological molecules of
leaf extract. Green synthesized OE-Ag NPs were successfully ...characterized using different spectroscopic techniques. Antibacterial activity of OE-Ag NPs was assessed against four different bacteriological strains using the dilution serial method. The cytotoxic potential was determined against MCF-7 carcinoma cells using MTT assay in terms of cell viability percentage. Antioxidant properties were evaluated in terms of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging. Biocompatibility was further examined by incubating the synthesized NPs with hMSC cells for 24 h. The results were demonstrated that synthesized OE-Ag NPs presented excellent log
reduction in the growth of all the tested bacterial strains, which as statistically equivalent (
> 0.05) to the standard antibiotic drug. Moreover, they also demonstrated excellent cytotoxic efficacy against the MCF-7 carcinoma cells compared to plant lead extract and Com-Ag NPs. Green synthesized OE-Ag NPs appeared more biocompatible to hMSC and 293T cells compared to Com-Ag NPs. Excellent biological results of the OE-Ag NPs might be attributed to the synergetic effect of NPs' properties and the adsorbed secondary metabolites of plant leaf extract. Hence, this study suggests that synthesized OE-Ag NPs can be a potential contender for their various biological and nutraceutical applications. Moreover, this study will open a new avenue to produce biocompatible nanoparticles with additional biological functionalities from the plants.
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