Organic optoelectronic devices have received appreciable attention due to their low cost, mechanical flexibility, band-gap engineering, lightness, and solution processability over a broad area. Specifically, realizing sustainability in organic optoelectronics, especially in solar cells and light-emitting devices, is a crucial milestone in the evolution of green electronics. Recently, the utilization of biological materials has appeared as an efficient means to alter the interfacial properties, and hence improve the performance, lifetime and stability of organic light-emitting diodes (OLEDs). Biological materials can be known as essential renewable bio-resources obtained from plants, animals and microorganisms. The application of biological interfacial materials (BIMs) in OLEDs is still in its early phase compared to the conventional synthetic interfacial materials; however, their fascinating features (such as their eco-friendly nature, biodegradability, easy modification, sustainability, biocompatibility, versatile structures, proton conductivity and rich functional groups) are compelling researchers around the world to construct innovative devices with enhanced efficiency. In this regard, we provide an extensive review of BIMs and their significance in the evolution of next-generation OLED devices. We highlight the electrical and physical properties of different BIMs, and address how such characteristics have been recently exploited to make efficient OLED devices. Biological materials such as ampicillin, deoxyribonucleic acid (DNA), nucleobases (NBs) and lignin derivatives have demonstrated significant potential as hole/electron transport layers as well as hole/electron blocking layers for OLED devices. Biological materials capable of generating a strong interfacial dipole can be considered as a promising prospect for alternative interlayer materials for OLED applications.
Polyethylene degradation has a significant ecological impact but is also economically beneficial because it generates fuels and useful chemical products. Our study mainly describes the cleavage of C-C and C-H bonds when polyethylene (dispersed in 1-octadecene) was low-temperature heat-treated in two steps, at 180 and 250 °C, for 24 h for each step. Finally, it was converted to a mixture of the precursors of gasoline and diesel oil with a trace amount of wax. A series of reactions resulted in cracking, dehydrogenation and oxidation, hence producing polycarboxylic acids and saturated and unsaturated hydrocarbons. ESI-MS analysis revealed that mixed oil consisted of low carbon number hydrocarbons and their derivatives of carboxylic acids, with the carbon number ranging from C-6 to C-18. In the trace amount of wax, complicated carboxylic acids and hydrocarbons with carbon number C-22 to C-58 were also identified. FT-IR analysis further confirmed the presence of carboxylic acid derivatives and double bonds in the degradation products. γ-Al2O3 nanorods effectively catalyzed the degradation process by enhancing the C-C chain length in the products. Lewis acid (Al) and Lewis base (oxygen) in the γ-Al2O3 induced ionic character of the C-C bond chain, which led to the efficient cracking of the C-C bond. Poor shielding effect, smaller atomic size and greater ionization energy made Ga a stronger Lewis acid compared to Al; hence, Ga-doped γ-Al2O3 catalyzed the degradation process even more effectively.
Wireless sensor networks (WSNs) are one of the fundamental infrastructures for Internet of Things (IoTs) technology. Efficient energy consumption is one of the greatest challenges in WSNs because of its resource-constrained sensor nodes (SNs). Clustering techniques can significantly help resolve this issue and extend the network's lifespan. In clustering, WSN is divided into various clusters, and a cluster head (CH) is selected in each cluster. The selection of appropriate CHs highly influences the clustering technique, and poor cluster structures lead toward the early death of WSNs. In this paper, we propose an energy-efficient clustering and cluster head selection technique for next-generation wireless sensor networks (NG-WSNs). The proposed clustering approach is based on the midpoint technique, considering residual energy and distance among nodes. It distributes the sensors uniformly creating balanced clusters, and uses multihop communication for distant CHs to the base station (BS). We consider a four-layer hierarchical network composed of SNs, CHs, unmanned aerial vehicle (UAV), and BS. The UAV brings the advantage of flexibility and mobility; it shortens the communication range of sensors, which leads to an extended lifetime. Finally, a simulated annealing algorithm is applied for the optimal trajectory of the UAV according to the ground sensor network. The experimental results show that the proposed approach outperforms with respect to energy efficiency and network lifetime when compared with state-of-the-art techniques from recent literature.
Complete recycling of Nd2Fe14B sludge by chemical methods has gained significance in recent years, however, it is not easy to recycle highly contaminant sludge and obtain product with good magnetic properties. Herein we report a simple four-step process to recycle the Nd2Fe14B sludge containing ~ 10% of contaminants. Sludge was leached in H2SO4 and selectively co-precipitated in two steps. In the first co-precipitation, Al3+ and Cu2+ were removed at pH 6. Thereafter, in the second co-precipitation Fe2+ and RE3+ sulfates were converted to the Fe and RE hydroxides. By annealing at 800 °C RE and Fe hydroxides precipitates were converted to the oxides and residual carbon was oxidized to CO2. After the addition of boric acid, Fe and RE oxides were reduced and diffused to the (Nd-RE)2Fe14B by calciothermic reduction diffusion. Removal of CaO by washing with D.I. water in glove box reduced the oxygen content (~ 0.7%), improved crystallinity and enhanced the magnetic properties significantly. Coercivity increased more than three times (from 242.71 to 800.55 kA/m) and Mr value was also enhanced up to more than 20% (from 0.481 to 0.605 T). In this green process Na2SO4 and Ca(OH)2 were produced as by-product those are non-hazardous and were removed conveniently.
Syntheses of Nd2Fe14B magnetic powder by conventional method is a complicated multi-step process, which produces harmful pollutants and consumes a huge amount of energy and resources. Herein we report a simple chemical route for the preparation of (Nd-Pr)2Fe14B magnetic powder using monazite concentrate as a precursor. Th, U, Sm, and La impurities were removed from monazite leachate by roasting, solvent extraction and leaching the concentrate. Purified leachate consisting of Nd and Pr Chlorides was added to the FeCl3 solution, and the solution produced was co-precipitated with NaOH. RE and Fe hydroxide precipitates were converted to the oxides by annealing at 700 °C. Boric acid and CaH2 were added in the RE and Fe oxides produced, and this mixture was reduced and diffused to (Nd-Pr)2Fe14B. Magnetic properties of the (Nd-Pr)2Fe14B produced were enhanced by introducing antiferromagnetic coupling, induced by Dy addition and efficient removal of CaO byproduct through ball milling in ethanol which increased the BHmax from 3.9 to 11.45 MGOe. Process reported is energy efficient, environment-friendly, time saving and low-cost.
SmCo5 and SmCo5-xCux magnetic particles were produced by co-precipitation followed by reduction diffusion. HRTEM confirmed the Cu substitution in the SmCo5 lattice. Non-magnetic Cu was substituted at "2c" site in the SmCo5 crystal lattice and effectively stopped the coupling in its surroundings. This decoupling effect decreased magnetic moment from SmCo5 (12.86 µB) to SmCo4Cu (10.58 µB) and SmCo3Cu2 (7.79 µB) and enhanced anisotropy energy from SmCo5 (10.87 Mega erg/cm3) to SmCo4Cu (14.05 Mega erg/cm3) and SmCo3Cu2 (14.78 Mega erg/cm3). Enhancement of the anisotropy energy increased the coercivity as its values for SmCo5, SmCo4Cu and SmCo3Cu2 were recorded as 4.5, 5.97 and 6.99 kOe respectively. Being six times cheaper as compared to Co, substituted Cu reduced the price of SmCo3Cu2 up to 2%. Extra 15% Co was added which not only enhanced the Mr value but also reduced the 5% of the total cost because of additional weight added to the SmCo3Cu2. Method reported in this work is most energy efficient method on the synthesis of Sm-Co-Cu ternary alloys until now.
Nd2Fe14B and Nd2-xDyxFe14B (x = 0.25, 0.50) particles were prepared by the modified co-precipitation followed by reduction-diffusion process. Bright field scanning transmission electron microscope (BF-STEM) image revealed the formation of Nd-Fe-B trigonal prisms in [- 101] viewing zone axis, confirming the formation of Nd2Fe14B/Nd2-xDyxFe14B. Accurate site for the Dy substitution in Nd2Fe14B crystal structure was determined as "f" site by using high-angle annular dark field scanning transmission electron microscope (HAADF-STEM). It was found that all the "g" sites are occupied by the Nd, meanwhile Dy occupied only the "f" site. Anti-ferromagnetic coupling at "f" site decreased the magnetic moment values for Nd1.75Dy0.25Fe14B (23.48 µB) and Nd1.5Dy0.5Fe14B (21.03 µB) as compared to Nd2Fe14B (25.50 µB). Reduction of magnetic moment increased the squareness ratio, coercivity and energy product. Analysis of magnetic anisotropy at constant magnetic field confirmed that "f" site substitution did not change the patterns of the anisotropy. Furthermore, magnetic moment of Nd2Fe14B, Nd2-xDyxFe14B, Nd ("f" site), Nd ("g" site) and Dy ("f" site) was recorded for all angles between 0° and 180°.
Nd2Fe14B is one of the most popular permanent magnets (PMs) possessing the best energy product (BH)max among the common PM materials. However, exchange-coupled nanocomposite magnets fabricated by embedding nanostructures of soft-phase magnetic materials into a hard-phase magnetic matrix manifest higher remanence and a higher energy product. Here we present the fabrication of exchange coupled Nd2Fe14B/Fe-Co magnetic nanocomposites using gel-combustion and diffusion-reduction processes. Pre-fabricated CoFe2O4 nanoparticles (NPs) of â¼5 nm diameter were incorporated into a Nd-Fe-B oxide matrix during its synthesis by gel-combustion. The obtained mixed oxide was further processed with oxidative annealing at 800 °C for 2 h and reductive annealing at 900 °C for 2 h to form a Nd2Fe14B/Fe-Co nanocomposite. Nanocomposites with different mol% of soft-phase were prepared and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and physical property measurement system (PPMS) to study their crystalline phase, morphology and magnetic behavior. Addition of 7.7 mol% of soft-phase was found to be optimum, producing a coercivity (H c) of 5.6 kOe and remanence (M r) of 54 emu g-1 in the nanocomposite.
In the title compound, C(15)H(14)N(2)O(5)S(2)·CH(4)O, the six-membered ring fused to the ß-lactam unit adopts a twisted conformation. In the crystal structure, the component mol-ecules are linked into a three-dimensional framework through inter-molecular N-Hâ¯S, N-Hâ¯O and O-Hâ¯O hydrogen bonds and C-Hâ¯O contacts.
