Investigation of thermal conductivity and rheological properties of nanofluids containing graphene nanoplatelets

In the present study, stable homogeneous graphene nanoplatelet (GNP) nanofluids were prepared without any surfactant by high-power ultrasonic (probe) dispersion of GNPs in distilled water. The concentrations of nanofluids were maintained at 0.025, 0.05, 0.075, and 0.1 wt.% for three different specific surface areas of 300, 500, and 750 m²/g. Transmission electron microscopy image shows that the suspensions are homogeneous and most of the materials have been well dispersed. The stability of nanofluid was investigated using a UV-visible spectrophotometer in a time span of 600 h, and zeta potential after dispersion had been investigated to elucidate its role on dispersion characteristics. The rheological properties of GNP nanofluids approach Newtonian and non-Newtonian behaviors where viscosity decreases linearly with the rise of temperature. The thermal conductivity results show that the dispersed nanoparticles can always enhance the thermal conductivity of the base fluid, and the highest enhancement was obtained to be 27.64% in the concentration of 0.1 wt.% of GNPs with a specific surface area of 750 m²/g. Electrical conductivity of the GNP nanofluids shows a significant enhancement by dispersion of GNPs in distilled water. This novel type of nanofluids shows outstanding potential for replacements as advanced heat transfer fluids in medium temperature applications including solar collectors and heat exchanger systems.     

Towards 5G: Context Aware Resource Allocation for Energy Saving

With the objective of providing high quality of service (QoS), 5G system will need to be context-aware that uses context information in a real-time mode depends on network, devices, applications, and the environment of users’. In order to continue enjoying the benefits provided by future technologies such as 5G, we need to find solutions for reducing energy consumption. One promising solution is taking advantage of the context information available in today’s networks. In this paper, we take a step towards 5G by utilizing context information in the scheduling process as conventional packet scheduling algorithms are mainly designed for increasing throughput but not for the energy saving. We investigate a Context Aware Scheduling (CAS) algorithm which considers the context information of users along with conventional metrics for scheduling. An information model of context awareness along with a context aware framework for resource management is also presented in this paper. CAS is simulated applying a system level simulator and the results obtained show that considerable amount of energy is saved by utilizing the context information compare to conventional scheduling algorithms.     

Thermomechanical behavior of bulk NiTi shape-memory-alloy microactuators based on bimorph actuation

Microsystem Technologies - Shape-memory-alloy (SMA) has attracted considerable attention in recent years as a smart and efficient material, due to its unique properties. SMA microactuators became...     

Bruton’s Tyrosine Kinase Targeting in Multiple Myeloma

Multiple myeloma (MM), a clonal plasma cell disorder, disrupts the bones’ hematopoiesis and microenvironment homeostasis and ability to mediate an immune response against malignant clones. Despite prominent survival improvement with newer treatment modalities since the 2000s, MM is still considered a non-curable disease. Patients experience disease recurrence episodes with clonal evolution, and with each relapse disease comes back with a more aggressive phenotype. Bruton’s Tyrosine Kinase (BTK) has been a major target for B cell clonal disorders and its role in clonal plasma cell disorders is under active investigation. BTK is a cytosolic kinase which plays a major role in the immune system and its related malignancies. The BTK pathway has been shown to provide survival for malignant clone and multiple myeloma stem cells (MMSCs). BTK also regulates the malignant clones’ interaction with the bone marrow microenvironment. Hence, BTK inhibition is a promising therapeutic strategy for MM patients. In this review, the role of BTK and its signal transduction pathways are outlined in the context of MM.     

Palladium catalyst performance for methane emissions abatement from lean burn natural gas vehicles

As little as 1 ppm SO_x present in the exhaust of a lean burn natural gas engine strongly inhibits the oxidation of CH₄ over a Pd containing catalyst. Non-methane emissions oxidation, such as C₂H₆, C₃H₈ and CO, are also inhibited by low SO_x concentrations, but to a lesser extent than CH₄ emissions. The mechanism for SO_x inhibition indicates a 1 : 1 selective adsorption of SO_x on PdO for palladium on a non-sulfating support such as SiO₂. Deactivation is therefore very rapid. In contrast, palladium on sulfating supports, that is γ-Al₂O₃, deactivate more slowly and can tolerate more SO_x because the SO_x is also adsorbed onto the carrier. The activation energy for methane oxidation is dramatically increased after SO_x poisoning for all Pd catalysts, while the Arrhenius pre-exponential term is relatively constant, indicating a transformation from very active PdO sites to less active PdOSO_x sites. Platinum catalysts are considerably less active than Pd as evidenced by a much lower pre-exponential term, but are more resistant to deactivation by SO_x. Non-methane hydrocarbon and particulate emissions standards for lean burn natural gas engines for the United States can be met with Pd catalysts. However, the non-enforced methane emissions standards are not met. For the European truck test cycle, methane emissions standards are met since the test cycle heavily weights the hotter modes where PdSO_x is sufficiently active.     

Histochemical evidences on the chronological alterations of the hypertrophic zone of mandibular condylar cartilage

The hypertrophic chondrocytes lack the ability to proliferate, thus permitting matrix mineralization as well as vascular invasion from the bone in both the mandibular condyle and the epiphyseal cartilage. This study attempted to verify whether the histological appearance of the hypertrophic chondrocytes is in a steady state during postnatal development of the mouse mandibular condyle. Type X collagen immunohistochemistry apparently distinguished the fibrous layer described previously as the "articular zone," "articular layer," and "resting zone" from the hypertrophic zone. Interestingly, the ratio of the type X collagen-positive hypertrophic zone in the entire condyle seemed higher in the early stages but decreased in the later stages. Some apparently compacted cells in the hypertrophic zone showed proliferating cell nuclear antigen (PCNA) immunoreaction, indicating the potential for cell proliferation at the early stages. As the mice matured, in contrast, they further enlarged and assumed typical features of hypertrophic chondrocytes. Apoptotic cells were also discernible in the hypertrophic zone at the early but not later stages. Consistent with morphological configurations of hypertrophic chondrocytes, immunoreactions for alkaline phosphatase, osteopontin, and type I collagen were prominent at the later stage, but not the early stage. Cartilaginous matrices demonstrated scattered patches of mineralization at the early stage, but increased in their volume and connectivity at the later stage. Thus, the spatial and temporal occurrence of these immunoreactions as well as apoptosis likely reflect the prematurity of hypertrophying cells at the early stage, and imply a physiological relevance during the early development of the mandibular condyles.     

Synthesis of In2O3/GNPs nanocomposites with integrated approaches to tune overall performance of electrochemical devices

The electroactive material with a porous structure, good electrical conductivity, hybrid composition, and a higher surface is considered more suitable for applications as an electrode in the energy storage device. Herein, we report the preparation of In₂O₃ nanoparticles via a simple chemical route and their nanocomposites with 10% (IOG-10), 30% (IOG-30), 50% (IOG-50), 70% (IOG-70), and 100% G-100 graphene nanoplatelets (GNPs) via ultra-sonication. The presence of GNPs in the nanocomposite samples was verified by powder X-ray diffraction (PXRD), Raman, and scanning electron microscopy (SEM) results. The prepared samples were loaded onto the porous 3D nickel foam (NF) substrate to manufacture the working electrode for electrochemical testing. The cyclic voltammetry (CV), as well as galvanostatic charge/discharge (GCD), results proposed the IOG-30@NF as a suitable electrode for electrochemical applications. More precisely, the IOG-30@NF electrode shows a specific capacitance of 1768 Fg^-1 at 1 Ag^-1, which is considerably higher than that of either G-100@NF or In₂O₃@NF electrodes. Besides, the IOG-30@NF electrode shows good cyclic stability of 92.2% after 4000 GCD tests completed at 12 Ag^-1. When increasing the current density value from 1 to 4, the IOG-30@NF electrode maintains a specific capability of 81%, ensuring its exceptional rate capability. The higher specific capacity, higher rate-performance, and better cyclic activity of the IOG-30@NF electrode can be ascribed to its hybrid-composition, nanoarchitecture In₂O₃, 3D but porous nickel foam substrate, appropriate graphene content, and interaction between In₂O₃ nanoparticles and GNPs nanosheets.     

Fabrication of binary metal doped CuO nanocatalyst and their application for the industrial effluents treatment

Herein, we fabricated the binary transition metal (Ce & Zn) doped CuO nanocatalyst via a single step facile co-precipitation technique by using liquid ammonia as a pH regulator and precipitating agent. The structural, morphological, and compositional studies of the fabricated samples were completed via X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and EDX techniques, respectively. The impact of binary metal-doped CuO nanocatalyst on the optical band-gap was examined via the UV-Visible spectroscopic technique. The photocatalytic aptitude of the fabricated pristine and binary metal-doped CuO nanocatalyst was examined against the 5-ppm aqueous solution of MB dye. The obtained results revealed that the doped sample removes 81.64% MB dye, via adsorption (32.65%) and degradation (48.99%) processes, while in comparison the pristine CuO sample removes just 38.77%. The superior adsorption and degradation aptitude of the binary metal-doped sample can be ascribed to its higher surface area and tuned band-gap, respectively. Moreover, the kinetic study of the degradation process also displayed that the doped sample degrades the MB dye with a higher value of the rate constant (0.0137 min^?1) than that of pristine CuO photocatalyst (0.0049 min^?1). The tuned band-gap and nanoarchitecture morphology of the doped CuO not only facilitate the excitation process but also assist in the transportation of the photo-induced species towards the surface of the photocatalyst. The observed superior photocatalytic activity of the binary metal-doped CuO photocatalyst showed its exceptional aptitude for the treatment of toxic industrial effluents.     

An Efficient Recyclable Polymer Supported Copper(II) Catalyst for C–N Bond Formation by <Emphasis Type=Italic>N</Emphasis>-Arylation

Abstract  

Polymer supported Cu(II) catalyst was prepared, characterized and employed for the N-arylation and amination reaction of N–H heterocycles with aryl halides as well as arylboronic acids to afford the corresponding coupled products in good to excellent yields. This catalyst can be used several times with consistent catalytic activity.     

Single Solvent‐Based Film Casting Method for the Production of Porous Polymer Films

A single solvent‐based film casting process for fabricating porous polymer films is developed in this study. The porous film is produced by mixing concentrated polylactic acid (PLA)/chloroform solution (20 wt%) and fresh chloroform solvent is followed by film casting. The average pore sizes of the films produced are seen to increase from 2.1 (±0.1) µm to 6.4 (±0.2) µm with increasing ratio of concentrated PLA solution and fresh solvent from 1:2 to 1:4. Functional groups of PLA after casting into porous film are confirmed via Fourier transform infrared spectroscopy analysis. Cytocompatibility studies (via Alamar Blue assessment) utilizing MG‐63 cells on the porous PLA films reveal an increase in cell metabolic activity up to 8 d postseeding. In addition, these direct cell culture studies show that the porous membranes support cell adhesion and growth not only on the surface but also through the porous structures of the membrane, highlighting the suitability of these porous films in tissue engineering applications.