PLA-TiO2 nanocomposites: Thermal,morphological, structural,and humidity sensing properties

In this paper, the effect of TiO₂ ceramic nanoparticles on the thermal stability, morphology, molecular mass, structure and electrical properties of the polylactic acid-Titanium dioxide (PLA-TiO₂) composites, aimed for relative humidity (RH) sensing have been reported. PLA-TiO₂ nanocomposites films were developed through a spin coating process. The developed films were characterized by X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and electrochemical impedance spectroscopy analysis (EIS). To investigate the RH-dependent characteristics, the devices were prepared on pre-patterned ITO substrates. The capacitive and resistive response of the nanocomposite films were studied under RH levels ranging from 20–90%. The PLA-TiO₂ nano-sensing films, having modified surface by acetone etching, exhibited superior morphological and electrical performance when compared to PLA-TiO₂ pristine samples.     

Modulating the burst drug release effect of waterborne polyurethane matrix by modifying with polymethylmethacrylate

To reduce cost and increase environmental friendliness, waterborne polyurethane (WPU) is a tempting choice in the field of green chemistry. Biodegradable WPU was synthesized using lysine as an internal emulsifier. WPU was further modified using methylate methacrylate (MMA) as an acrylic monomer. Unsaturated pre-PU was synthesized by using unsaturated end-capping agent 2-hydroxyethyl methacrylate and further extended by MMA to form acrylate modified WPU. A permanent covalent linkage was established between WPU and PMMA as confirmed by FTIR spectroscopy. The focus of this research work was to study the dependence of drug delivery, mechanical, thermal, surface, and structural properties of WPU, on the MMA repeating unit content (10%–40%). For drug release studies mitomycin c was taken as a model anticancer drug. Furthermore, these materials were subjected to in vitro and in vivo cytotoxicity evaluation, which shows that synthesized acrylate modified WPU are biocompatible. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47253.     

Communication Requirements and Interconnect Optimization for High-End Scientific Applications

The path toward realizing next-generation petascale and exascale computing is increasingly dependent on building supercomputers with unprecedented numbers of processors. To prevent the interconnect from dominating the overall cost of these ultrascale systems, there is a critical need for scalable interconnects that capture the communication requirements of ultrascale applications. It is, therefore, essential to understand high-end application communication characteristics across a broad spectrum of computational methods, and utilize that insight to tailor interconnect designs to the specific requirements of the underlying codes. This work makes several unique contributions toward attaining that goal. First, we conduct one of the broadest studies to date of high-end application communication requirements, whose computational methods include: finite difference, lattice Boltzmann, particle-in-cell, sparse linear algebra, particle-mesh ewald, and FFT-based solvers. Using derived communication characteristics, we next present the fit-tree approach for designing network infrastructure that is tailored to application requirements. The fit-tree minimizes the component count of an interconnect without impacting application performance compared to a fully connected network. Finally, we propose a methodology for reconfigurable networks to implement fit-tree solutions. Our Hybrid Flexibly Assignable Switch Topology (HFAST) infrastructure, uses both passive (circuit) and active (packet) commodity switch components to dynamically reconfigure interconnects to suit the topological requirements of scientific applications. Overall, our exploration points to several promising directions for practically addressing the interconnect requirements of future ultrascale systems.     

Sputtering of graphite in pulsed and continuous arc and spark discharges

The environment that leads to the sputtering of graphite electrodes and formation of carbonaceous discharge has been studied with emission spectroscopy. Population level densities, excitation & vibrational temperatures and electron densities have been obtained from a set of three ion sources. The sources operate in continuous and pulsed discharge modes. The sputtered species include monatomic, diatomic and higher carbon clusters. The main sputtered species are excited and ionized C₁ (CI, CII, respectively) and C₂. In the continuous arc discharge the vibrational temperature derived from the Swan band of C₂ is ∼10,000 K, whereas, in the pulsed arc the excitation temperature of Neon is ∼11,000 K. The spark discharge yields an average excitation temperature of CI and NI ∼ 5500 K.     

Frictional power loss in solid‐grease‐lubricated needle roller bearing

The use of solid grease as a lubricant, in comparison with standard grease or oil, is a pre‐requisite when needle roller bearings undergo a high‐speed oscillating motion and when access to the bearing is difficult for maintenance purposes. This paper examines the frictional power loss of a solid‐grease‐lubricated needle roller bearing. First set of measurement result reveals that the test bearing has higher frictional power loss as compared with other bearings with conventional lubrications, due to the high viscosity of the solid grease. Furthermore, measurements are compared with the Palmgren and SKF models. For improving these models, the parameters of the models are updated on the basis of the measurement data. A second set of measurement result shows that the use of oil (kept at higher temperature) in addition to solid grease significantly reduces the frictional power loss. The reduction is due to the decrease in operational viscosity of the solid grease. Copyright © 2012 John Wiley & Sons, Ltd.     

Preparation of PVC/PVP composite polymer membranes via phase inversion process for water treatment purposes

In this work, new composite membranes were successfully prepared via phase inversion technique using polyvinyl chloride(PVC) and polyvinylpyrrolidone(PVP) as polymers and tetrahydrofuran(THF) and N-methyl-2-pyrrolidone(NMP) as solvents. The prepared membranes have been characterized by scanning electron microscope(SEM), and fourier transforms infrared spectroscopy(FTIR). The scanning electron microscope results prove that the prepared membranes are smooth and their pores are distributed throughout the whole surface and bulk body of the membrane without any visible cracks. The stress–strain mechanical test showed an excellent mechanical behavior enhanced by the presence of PVP in the prepared membranes. The membranes performance results showed that the salt rejection reached 98% with a high flux. This, in turn, makes the prepared membranes can be applied for sea and brackish water treatment through membrane distillation technology.     

A study of fullerite ablation with energetic pulsed electrons

We report the ablation of fullerite films deposited on metallic substrates with 3 keV electron pulses generated in a specially designed pulsed discharge tube. During ablation the fragmented species were detected by emission spectroscopy. The emission spectra of C₂ and C₁^∗ (CII) provide the signatures of C₆₀ fragmentation. The vibrational temperature of the C₂ emitted from the ablated fullerite is ∼12,700 ± 1160 K compared with ∼18,230 ± 1150 K for the graphite sample under similar conditions. The fullerite films were produced by vacuum sublimation on Aluminum, Iron and Copper substrates and characterized by Atomic force microscope, X-ray diffraction; Raman and Fourier transform infrared spectroscopy. The comparisons of electron ablation of fullerite films with that of graphite show the similarities and differences of carbon bonding in the caged structure of C₆₀ with that of the planar graphene sheets of graphite.     

Complexity reduction of equalization/pre-emphasis using set membership filtering for NG LR-PON

Coherent receivers, with advanced and low-complexity digital signal processing (DSP), have the advantage of increasing the loss/power budget of next generation-long-reach passive optical networks (NG-LRPONs). This reduces the network capital expenditures by eliminating or reducing the number of amplifiers to be installed between the optical line terminal (OLT) and the optical network units (ONUs). In this paper, we investigate the complexity and convergence speed of two adaptive equalization and/or pre-emphasis strategies for mitigating chromatic and polarization mode dispersions (CD and PMD) in NG-LRPON. We first identify two potential deployment strategies of equalization and/or pre-emphasis. The first equally splits the signal processing in the OLT and ONU; however, the second concentrates most of DSP in the OLT trying to reduce the cost and alleviate the complexity of ONUs. Our investigation shows that the second strategy achieves 50 % faster convergence rate in terms of number of symbols for 16QAM/5 Gbaud. Moreover, we apply the enhanced set membership filtering (SMF) technique, recently introduced for next generation wireless communications, to our LR-PON in order to reduce the update rate of equalizers’ taps, hence reduce the calculation complexity of the OLT and ONUs. Our results show that by employing SMF technique a substantial reduction in the number of mathematical operations needed to attain convergence is achieved. Simulation results reveal that our proposed SMF can reduce the equalizers’ update rate, hence calculation complexity, by 55 % for 16QAM and 75 % for QPSK with marginal degradation of the BER.