Polyoxometalates (POMs) represent a class of nanomaterials, which hold enormous promise for a range of energy-related applications. Their promise is owing to their “special” structure that gives POMs a truly unique ability to control redox reactions in energy conversion and storage. One such amazing capability is their large number of redox active sites that arises from the complex three-dimensional cluster of metal-oxide ions linked together by oxygen atoms. Here, a critical review on how POMs emerged from being molecular clusters for fundamental studies, to next-generation materials for energy applications is provided. We highlight how exploiting the versatility and activity of these molecules can lead to improved performance in energy devices such as supercapacitors and batteries, and in energy catalyst applications. The potential of POMs across numerous fields is systematically outlined by investigating structure–property–performance relationships and the determinant factors for energy systems. Finally, the challenges and opportunities for this class of materials with respect to addressing our pressing energy-related concerns are identified.

Polyoxometalates (POMs): from electroactive clusters to energy materials

Drilling is the most commonly used machining operation among others for assembly applications. The necessity of this operation has come to the forefront in composite materials that are becoming widespread nowadays. In this study, drilling performance of glass fiber reinforced plastic (GFRP) composite pipes used in many sectors such as natural gas transmission lines, pressurized sewer lines, industrial waste transmission, defense industry, and construction industry was investigated. The GFRP pipe was produced by filament winding method with a winding angle of ±55°. Different drill types (conventional twist drill, brad and spur drill, and brad center drill) with a drill diameter of 4 mm were utilized for drilling the pipe and the effect of drill type on the drilling performance was investigated. Drilling tests were performed at a constant 5000 rpm spindle speed and six different feed rate parameters (25, 75, 125, 175, 225, and 275 mm/min). Thrust forces generated during drilling were recorded and after the drilling operations, hole exit surface damage, and borehole surface damage were examined by a digital microscope and scanning electron microscope (SEM). Results showed that the brad center drill produced lower thrust forces while the twist drill generated higher thrust forces. The severity of damages could vary depending on the tool geometry and feed rate. Especially, at lower feed rates, conventional twist drill results with increased delamination and uncut fibers as compared with other drills. The brad center drill presents better performance since it generates fewer damages. Also, it is observed that these damages formed in the winding angle direction (orientation).

An experimental study on the effects of various drill types on drilling performance of GFRP composite pipes and damage formation

Nowadays, filament wound composite pipes (GRP) are used as a structural element in many applications such as natural gas and oil transmission lines, and portable bridge constructions for military purposes. GRP pipes can expose to impact loading from various causes. This loading can cause an invisible level of damage. Thus, the detection and evaluation of such damages are of great importance. In this study, the low velocity impact response of (±55°)3 filament wound E-glass/epoxy composite pipes has been studied. The pipes have been subjected to drop weight impact loading with various impact energies. The force-time and force-displacement relations have been examined. The impact damage formation was also evaluated. It is concluded that the damage development in the pipes is controlled by displacement trough radial direction. The obtained results were evaluated statistically by means of Weibull approach. Microscopy analysis of impacted region revealed that debonding, radial cracks, transfer cracks and delamination damage modes are the main observed damage modes.

Experimental and statistical analysis of low velocity impact response of filament wound composite pipes

Enhanced surface plasmon resonance (SPR) signals based on immobilization of core-shell nanoparticles incorporated boron nitride nanosheets: Development of molecularly imprinted SPR nanosensor for anticancer drug, etoposide.

Nanotechnology holds huge potentials in several fields and is envisaged as a technology to lead the way toward sustainable environment-friendly development in the coming years. The basic theme of nanotechnology is to use particles having size in nanometer range for various applications in medical fields, cosmetics industry, and agriculture and food technologies. The benefits associated with nanotechnology include among others increase in yield and quality of produce in agriculture, improved cosmetic products, directed delivery of medicines and sensor applications. Advancement in the development of nanosensors has made recognition of disease causing elements, toxins and nutrients in foods, and elements in environmental samples, easier and cost effective. However, immense focus on nanotechnology in past few decades has led to its unrestricted development and consequently enormous use of nanoparticles (NPs). It is considered that NPs may pose risks to the environment and biological systems. It is also becoming evident that the size, structure and type of nanomaterials, such as graphene/graphene oxide with gold NPs, carbon and carbon nitride nanotubes, have different effects on plants and environment. Hence, long-term life cycle analyses are needed to assess impacts of NPs. This review presents a brief overview of applications of nanomaterials in agriculture and discusses its positive and negative aspects in agricultural field. The review emphasizes that future development of nanotechnology must be based on scientific evaluations of benefits and risks associated to it in long term.

A review on positive and negative impacts of nanotechnology in agriculture

Fabrication of Pt/Pd nanoparticles/polyoxometalate/ionic liquid nanohybrid for electrocatalytic oxidation of methanol

In this study, composites composed of glass fiber reinforced-epoxy laminates interleaved with electrospun polyvinylchloride (PVC) nano-fibres were designed for radar absorption investigations. The laminated composites which were produced in special molds were obtained by placing woven glass fibers between each of PVC nanofiber mats, and the composites were produced in three different forms as pure, multi-walled carbon nanotubes doped and graphene doped. The morphologies of the PVC nanofiber mats were analyzed by scanning electron microscope. The radar absorption efficiencies of the composites in the individual and different combinations were measured in the 3–8 GHz frequency band. Experimental results show that the produced graphene-added composite material has improvable microwave absorption effect at several points in 3–8 GHz band to provide excellent absorption in future studies. The graphene doped structure was found to have a certain absorption characteristic up to 33.82% at a constant frequency. Besides, various strong absorption frequency points have been obtained in the related frequency range. The cascaded graphene doped composite layers can provide broadband absorption for stealth technology.

Electromagnetic Scattering Properties of MWCNTs/Graphene Doped Epoxy Layered with PVC Nanofiber/E-Glass Composites

http://www.theijes.com/papers/v5-i11/Version-2/M0511028689.pdf

The Effect of Nylon 6.6 Nanofiber Layers on Mechanical Properties of Epoxy

In this study, it was aimed to determine the heavy metal pollution in the agricultural lands around Hatay airport and travel possible alteration in the amount of heavy metal on the land in accordance with the distance to the airport. For this purpose, the airport was chosen as the center and 27 soil samples were obtained around the airport at 2 km intervals in depth ranging from 0 to 30 cm. Lead (Pb), cadmium (Cd), nickel (Ni), chrome (Cr), cobalt (Co), aluminium (Al), iron (Fe), copper (Cu), manganese (Mn) and zinc (Zn) elements in soil samples were analysed using MP-AES instrument by DTPA method. (3 repetition for each sample). As a result of the analysis, heavy metal concentrations were found as Pb 0-1.45 mg/kg, Cd 0-0.220 mg/kg, Ni 0-3.95 mg/kg, Cr 0-0.780 mg/kg, Co 0-0.270 mg/kg, Al 0-0.700 mg/kg, Fe 1.47- 16.2 mg/kg, Cu 0.400-5.35 mg/kg, Mn 0-19 mg/kg and Zn 0.050-3.14 mg/kg. When comparing the obtained data through this study with allowable concentrations of heavy metals in soil of Environment and Forest Directorates Guidance, it was determined that the heavy metal concentration of the soil does not pose any problems in terms of heavy metal pollution. Besides, iron concentration was decreased when the distance to the airport is increased.

/pdf/heavy-metal-pollution-around-international-hatay-airport-7o42qd9ac1.pdf

Heavy Metal Pollution Around International Hatay Airport

In this study, the holes of glass fiber reinforced polymer (GFRP) and multi-walled carbon nanotubes (MWCNTs) doped GFRP composite materials were drilled using abrasive water jet (AWJ), CO2 laser cutting, orbital drilling, and punching methods; the effects of these methods on hole quality were determined. The hole entry and exit dimensions were obtained equal and in the desired size by orbital drilling; thus, kerf formation was prevented due to the lateral and face milling of the end mill. The surface hardness change was not observed in the hole circles obtained with the orbital drilling and punching methods. However, epoxy hardening was observed in the hole circles obtained by laser cutting due to the heat effect of laser beam. In AWJ method, matrix-fiber integrity was disrupted, and delamination was observed due to the effect of water pressure and kinetic energy; consequently an increase in material thickness was observed and surface hardness decreased. It was determined that MWCNTs additive increased the surface hardness of composites and maintained its hardness and durability in post-cutting measurements. Splintering and burring were not seen in any method, but fiber carbonization was observed in the inner parts of the hole due to thermal effects in laser cutting.

Vildan Özkan

Papers

Fabrication of Pt/Pd nanoparticles/polyoxometalate/ionic liquid nanohybrid for electrocatalytic oxidation of methanol

Electromagnetic Scattering Properties of MWCNTs/Graphene Doped Epoxy Layered with PVC Nanofiber/E-Glass Composites

The Effect of Nylon 6.6 Nanofiber Layers on Mechanical Properties of Epoxy

Heavy Metal Pollution Around International Hatay Airport

MWCNTs doped GFRPs drilling: crosscheck among holes obtained by alternative manufacturing methods