Processable Thermally Conductive Polyurethane Composite Fibers

The demand for wearable electronics has resulted in an increasing interest in the development of functional fibers, with a specific focus upon the development of electrically conductive fibers incorporable into garments. However, the production of thermally conductive fibers for heat dissipation has been largely neglected. Owing to the very rapid development of miniaturized wearable electronics, there is an increasing need for the development of thermally conductive fibers as heat sinks and thermal management processes. In this study, thermally conductive but electrically insulating boron nitride nanopowder (BNNP) fillers are used to effectively enhance the thermal conductivity and mechanical properties of elastomeric polyurethane fibers. Thermal conductivity enhancement of more than 160% is achieved at very low loadings of BNNP (less than 5 wt%) with an improvement in the mechanical properties of the unmodified fiber. These thermally conductive fibers are also incorporated into 3D textile structures as a proof of processability.     

Palladium,silver, and zinc oxide nanoparticles loaded on activated carbon as adsorbent for removal of bromophenol red from aqueous solution

The adsorption of bromophenol red (BPR) onto three adsorbents including palladium, silver and zinc oxide nanoparticles loaded on activated carbon (Pd-NP-AC, Ag-NP-AC and ZnO-NP-AC) in a batch system has been studied and the influence of various parameters has been optimized. The influence of time on removal of BPR on all adsorbent was investigated and experimental data were analyzed by four kinetic models including pseudo first and second-order, Elovich and the intraparticle diffusion equations. Following fitting the experimental data to these models, the respective parameters of each model such as rate constants, equilibrium adsorption capacities and correlation coefficients for each model were investigated and based on well known criterion their applicability was judged. It was seen that the adsorption of BPR onto all adsorbents sufficiently described by the pseudo second-order equation in addition to interparticle diffusion model. The adsorption of BPR on all adsorbent was investigated at various concentration of dye and the experimental equilibrium data were analyzed and fitted to the Langmuir, Freundlich, Tempkin, Dubinin, and Radushkevich equations. A single stage in batch process was efficient and suitable for all adsorbents using the Langmuir isotherm with maximum adsorption of 143 mg g^?1 for Pd-NP-AC, 250 mg g^?1 for Ag-NP-AC and 200 mg g^?1 for ZnO-NR-AC. Thermodynamic parameters such as ΔG°, ΔH°, and ΔS° for Pd-NP-AC adsorbent were calculated.     

Study of removal of Direct Yellow 12 by cadmium oxide nanowires loaded on activated carbon

In this research, cadmium oxide nanowires loaded on activated carbon (CdO-NW-AC) has been synthesized by a simple procedure and characterized by different techniques such as XRD, SEM and UV–vis spectrometry. This new adsorbent has been efficiently utilized for the removal of the Direct Yellow 12 (DY-12) from wastewater. To obtain maximum DY-12 removal efficiency, the influences of variables such as pH, DY-12 concentration, amount of CdO-NW-AC, contact time, and temperature have been examined and optimized in a batch method. Following the variable optimization, the experimental equilibrium data (at different concentration of DY-12) was fitted to conventional isotherm models such as Langmuir, Freundlich and Tempkin. The applicability of each method is based on the R² and error analysis for each model. It was found that the experimental equilibrium data well fitted to the Langmuir isotherm model. The dependency of removal process to time and the experimental data follow second order kinetic model with involvement of intraparticle diffusion model. The negative value of Gibbs's free energy and positive value of adsorption enthalpy show the spontaneous and endothermic nature of adsorption process.     

Transformation Mechanism of Preprecipitation NiMn Nanostructures

The transformation mechanism of constrained b.c.c NiMn (β phase) clusters coherently precipitated during isothermal aging of Fe-Ni-Mn maraging alloy at 753 K (480 °C) has been studied. Preprecipitation of β-NiMn phase was demonstrated using conventional and high-resolution transmission electron microscopy and confirmed by flanking of electron diffraction spots, X-ray diffraction sidebands, and the invariance of lattice parameter and peak breadths in the earlier stages of age hardening. The β-NiMn clusters were recognized with interfacial dislocation dipoles lying on {011} _α planes and Burgers vectors of a ₀ $ \left\langle {01\overline{1} } \right\rangle_{\alpha } $ type. During further aging, the β-NiMn clusters transformed martensitically into fct NiMn (θ phase) precipitates as envisaged by the characteristic microtwinning texture. Considering the anomalous elastic softness of β-NiMn alloy, the transformation was plausibly assumed to take place by the localized soft-mode mechanism in which the structural instability of clusters is stimulated by the strain field of the interfacial dislocations. Computerized calculations in accordance with the phenomenological theory of martensite crystallography indicated that microtwinning of martensitic θ precipitates occurs in a self-accommodating manner. Transformation of very small β clusters at earlier stages of aging is thermodynamically hampered by the interfacial energy barrier.     

Comparison of the efficiency of palladium and silver nanoparticles loaded on activated carbon and zinc oxide nanorods loaded on activated carbon as new adsorbents for removal of Congo red from aqueous solution: Kinetic and isotherm study

The adsorption of Congo red (CR) into three new adsorbents including Palladium and silver nanoparticles loaded on activated carbon (Pd NPs-AC, Ag NPs-AC) and zinc oxide nanorods loaded on activated carbon (ZnO-NRs-AC) in a batch method has been studied following the optimization of effective variables including pH, amount of adsorbents and time. The experimental data was fitted to conventional kinetic models including the pseudo first-order and second-order Elovich and intraparticle diffusion model and based on calculated respective parameters such as rate constants, equilibrium adsorption capacities and correlation coefficients. It was found that for all adsorbents the removal process follows the pseudo second other kinetic model with involvement of interparticle diffusion model. The experimental isotherm data were analyzed using the Langmuir, Freundlich, Tempkin and Dubinin and Radushkevich equations and it was found for all adsorbents that the removal process followed the Langmuir isotherm.     

Chemiresistive Sensor Arrays for Gas/Volatile Organic Compounds Monitoring: A Review

Gas detection and monitoring are essential due to their direct impact on human health, environment, and ecosystem. Chemiresistive sensors are one of the most used classes of sensors for monitoring and measurement of gases thanks to their ease of fabrication, customizability, mechanical flexibility, and fast response time. While chemiresistive sensors can offer good sensitivity and selectivity to a particular gas in a controlled environment with known interferences, they may not be able to differentiate between various gases having similar physiochemical properties under uncontrolled conditions. To address this shortcoming of chemiresistive gas sensors, sensor arrays have been the subject of recent studies. Gas sensor arrays are a group of individual gas sensors that are arranged to simultaneously detect and differentiate multiple cross-reactive gases. In this regard, various sensor array technologies have been developed to differentiate a given set of gases using multivariate algorithms. This review provides an insight into the different algorithms that are used to extract the data from the sensor arrays, highlighting the fabrication techniques used for developing the sensor array prototypes, and different applications in which these arrays are used.     

Effects of cold rolling on the microstructure and mechanical properties of Fe-Ni-Mn-Mo-Ti-Cr maraging steels

Effects of cold rolling on the microstructure and mechanical properties of Fe-Ni-Mn-Mo-Ti-Cr maraging steels were studied.To investigate the microstructure and mechanical properties,optical microscopy,scanning electron microscopy,X-ray diffraction,tensile test,and hardness test were used.The results show that the solution-annealing treatment in the cold-rolled steel redounds to the formation of submicrocrystalline Fe2(Mo,Ti)Laves phase particles,which are stable at high temperatures.These secondary Laves phase particles prevent from recrystallization at high temperatures and correspond to semi-brittle fiacture in the subsequent aging treatment.     

Ab initio and TD-DFT study of the structural and spectroscopic properties of C30H10 as a new buckybowl

In this study, the structural and spectroscopic properties of the C₃₀H₁₀ as a sub-fullerene and a new buckybowl was carried out by quantum mechanical computations using B3LYP method and 6–311++G(d,p) basis set. All of the parameters were evaluated by density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were described which revealed different charge transfer possibilities for the molecule. The chemical shifts (δ, ppm) were predicted for ¹H and ¹³C atoms using GIAO method. Natural bond orbital (NBO) analysis was carried out to picture the charge transfer between the localized bonds and lone pairs. The Fukui function (FF) for local reactivity of C₃₀H₁₀ was calculated and related discussions were done.     

Effect of Solidification Texture on the Magnetostrictive Behavior of Galfenol

This study investigates the magnetostrictive functionality of crystallographic textures developed by directional solidification of a vacuum-melted galfenol cast button. A polycrystalline Fe_82.4Ga_17.6 alloy was melted using vacuum arc melting and solidified in a water-cooled copper mold. Optical metallography confirmed the development of large columnar grains in the solidification microstructure. Phase constitution and magnetic domain structures of sample were studied by X-ray diffraction (XRD) and magnetic force microscopy (MFM). The results showed that the cast button has a disordered body-centered cubic (bcc) (A2) single-phase structure that consisted of a combination of well-aligned stripe-like and maze-like magnetic domains. To investigate the magnetostriction behavior, a couple of pins were cut along columnar grains as well as in the transverse direction. Magnetostriction was measured in the presence of an externally applied magnetic field. It was found that pins cut along the columnar grains comprised very high magnetostriction, whereas transverse pins had lower magnetostriction against the applied field.