Tribological Characteristics of Aqueous Graphene Oxide,Graphitic Carbon Nitride,and Their Mixed Suspensions

The tribological performance of graphene oxide (GO), graphitic carbon nitride (g-C₃N₄), and their mixed (g-C₃N₄/GO) aqueous suspensions was investigated. The 0.06 wt% GO, 0.06 wt% g-C₃N₄, and 0.06 wt% 1:1 g-C₃N₄/GO suspensions reduced the coefficient of friction (COF) by 37, 26 and 37% and wear mark radius by 19.1, 16.0 and 19.6%, respectively, in comparison with water. Pure g-C₃N₄ and GO suspensions showed unstable lubrication in the tests with relatively high loads and speeds, while the g-C₃N₄/GO mixed suspension had superior tribological performance in all tested conditions. This is because in the mixed suspension g-C₃N₄ agglomerates became smaller, and GO nanosheets exhibited fewer wrinkles and less stacking, which enabled the formation of a layer of tribo-composite film. As a result, the friction, wear and tribo-corrosion were reduced during sliding.     

Producing Polydicyclopentadiene from Lower-Grade Dicyclopentadiene

Russian Engineering Research - Polymer samples based on polydicyclopentadiene produced from Russian dicyclopentadiene are investigated by thermogravimetric analysis and differential scanning...     

Fabrication and characterization of poly(methyl methacrylate)/CaCu3Ti4O12 composites

Composites comprising Poly(Methyl Methacrylate) (PMMA) and CaCu₃Ti₄O₁₂ (CCTO) via melt mixing followed by hot pressing were fabricated. These were characterized using X‐ray diffraction, thermo gravimetric, scanning electron microscopy, and Impedance analyzer for their structural, morphology, and dielectric properties. Composites were found to have better thermal stability than that of pure PMMA. The composite, with 38 Vol % of CCTO (in PMMA), exhibited remarkably low dielectric loss at high frequencies and the low frequency relaxation is attributed to the space charge polarization/MWS effect. Theoretical models were employed to rationalize the dielectric behavior of these composites. At higher temperatures, the relaxation peak shifts to higher frequencies, due to the merging of both β and α relaxations into a single dielectric dispersion peak. The AC conductivity in the high frequency region was attributed to the electronic polarization. POLYM. ENG. SCI., 54:551–558, 2014. © 2013 Society of Plastics Engineers     

Carbon nanotubes/amorphous carbon composites as high-power negative electrodes in lithium ion capacitors

A nitrogen-rich carbon nanotubes/amorphous carbon (CNT/C) composite was prepared by carbonising a CNT/polyaniline (PANI) composite, and characterised. Scanning electron microscopy and X-ray photoelectron spectroscopy confirmed that the composite retained a mesoporous CNT structure as its backbone, whilst the nitrogen-rich PANI-derived carbon formed a thin amorphous coating on the CNT surface. Electrochemical characterisation of the CNT/C composite indicated that it had nearly double the reversible Li⁺ intercalation capacity (390 vs. 219 mAh g^?1) and 39 % less irreversible capacity (622 vs. 1,015 mAh g^?1) than the pristine CNT. The CNT/C composite showed exceptionally high rate capability with a de-intercalation capacity of 81 mAh g^?1 at a very high charge/discharge rate of 60 C (time taken for charge or discharge is 1 min) (1 C = 1 h charge or discharge), whereas the pristine CNT delivered 53 mAh g^?1 at this C-rate. By comparison, the rate capabilities of conventional graphite (N3 and SLP30) were very poor above 5 C (~17 mAh g^?1 at 5 C). Both the pristine CNT and CNT/C composite showed an excellent cyclability at 1 C charge/discharge over 600 cycles. The CNT/C composite maintained a fairly stable capacity of ~200 mAh g^?1 after 600 cycles, whilst the commercial graphite showed a steady and significant decrease in de-intercalation capacity; reaching <70 mAh g^?1 after 600 cycles.     

Mobility Analysis of 2 nm to 11 nm Aerosol Particles with an Aspirating Drift Tube Ion Mobility Spectrometer

We describe the performance of a drift tube-ion mobility spectrometry (DT-IMS) instrument for the measurement of aerosol particles. In DT-IMS, the electrical mobility of a measured particle is inferred directly from the time required for the particle to traverse a drift region, with motion driven by an electrostatic field. Electrical mobility distributions are hence linked to arrival time distributions (ATDs) for particles reaching a detector downstream of the drift region. The developed instrument addresses two obstacles that have limited DT-IMS use for aerosol measurement previously: (1) conventional drift tubes cannot efficiently sample charged particles at ground potential and (2) the sensitivities of commonly used Faraday plate detectors are too low for most aerosols. Obstacle (1) is circumvented by creating a “sample volume” of aerosol for measurement, defined by the streamlines of fluid flow. Obstacle (2) is bypassed by interfacing the end of the drift region with a condensation particle counter. The DT-IMS prototype shows high linearity for arrival time versus inverse electrical mobility (R ² > 0.99) over the size range tested (2.2–11.1 nm), and measurements compare well with both analytical and numerical models of device performance. A dimensionless calibration curve linking drift time to inverse electrical mobility is developed. In less than 5 s, it is possible to measure 11.1 nm particles, while 2.2 nm particles are analyzable on a subsecond scale. The transmission efficiency is found to be dependent upon electrostatic deposition for short drift times and upon advective losses for long drift times.

Copyright 2014 American Association for Aerosol Research     

Mitigation of Soot Deposition in Exhaust Gas Recirculation Coolers Using a Spiral Insert

In diesel engines, the emission of nitrogen oxides can profoundly be controlled by using exhaust gas recirculation (EGR) coolers. Nevertheless, the deposition of unwanted materials, in form of primarily particulate matter and hydrocarbons, causes a major hurdle to the durability of such devices. In this study, a novel technique, i.e., a spiral insert, has been developed to mitigate particulate fouling in tubular EGR coolers. It is made of a helical rotating blade which is inserted inside the tubes of EGR coolers, and it rotates around its axis under the force of entering gas flow. As the blade rotates, it wipes out the deposit. An EGR experimental setup has also been used to examine how effective the spiral insert is in suppressing particulate fouling for two different gas velocities with and without using the insert. With no insert, the deposition was severe, fast, and continuous. For the latter, though, it was first very slow, and second, the fouling resistance was four times lower to that of no insert. No sign of any deposit was also observed on the insert after fouling runs. Despite the promising results, the insert requires further development so it can rotate at the low gas velocities.

Copyright 2014 American Association for Aerosol Research     

Hydrogenated silicon oxycarbonitride films. Part II. Physicochemical and functional properties

The optical, and electrophysical characteristics of hydrogenated silicon oxycarbonitride films synthesized by the plasma enhanced chemical vapor decomposition of the mixtures of 1,1,1,3,3,3-hexamethyldisilazane with oxygen and nitrogen in the temperature range of 373–973 K have been studied. It has been shown that the obtained films are highly transparent (transmittance is ～92–99%) in the UV, visible, and IR ranges of the spectrum; they have refractive indices in the range of 1.43–2.25, a low reflection coefficient of visible light (nearly 3%), and low dielectric permittivity.     

Microenvironment of Tumor-Draining Lymph Nodes: Opportunities for Liposome-Based Targeted Therapy

The World Health Organization (WHO) recently reported that the total number of global cancer cases in 2013 reached 14 million, a 10% rise since 2008, while the total number of cancer deaths reached 8.2 million, a 5.2% increase since 2008. Metastasis is the major cause of death from cancer, accounting for 90% of all cancer related deaths. Tumor-draining lymph nodes (TDLN), the sentinel nodes, are the first organs of metastasis in several types of cancers. The extent of metastasis in the TDLN is often used in disease staging and prognosis evaluation in cancer patients. Here, we describe the microenvironment of the TDLN and review the recent literature on liposome-based therapies directed to immune cells within the TDLN with the intent to target cancer cells.     

Long-Term Spinal Ventral Root Reimplantation,but not Bone Marrow Mononuclear Cell Treatment,Positively Influences Ultrastructural Synapse Recovery and Motor Axonal Regrowth

We recently proposed a new surgical approach to treat ventral root avulsion, resulting in motoneuron protection. The present work combined such a surgical approach with bone marrow mononuclear cells (MC) therapy. Therefore, MC were added to the site of reimplantation. Female Lewis rats (seven weeks old) were subjected to unilateral ventral root avulsion (VRA) at L4, L5 and L6 levels and divided into the following groups (n = 5 for each group): Avulsion, sealant reimplanted roots and sealant reimplanted roots plus MC. After four weeks and 12 weeks post-surgery, the lumbar intumescences were processed by transmission electron microscopy, to analyze synaptic inputs to the repaired α motoneurons. Also, the ipsi and contralateral sciatic nerves were processed for axon counting and morphometry. The ultrastructural results indicated a significant preservation of inhibitory pre-synaptic boutons in the groups repaired with sealant alone and associated with MC therapy. Moreover, the average number of axons was higher in treated groups when compared to avulsion only. Complementary to the fiber counting, the morphometric analysis of axonal diameter and “g” ratio demonstrated that root reimplantation improved the motor component recovery. In conclusion, the data herein demonstrate that root reimplantation at the lesion site may be considered a therapeutic approach, following proximal lesions in the interface of central nervous system (CNS) and peripheral nervous system (PNS), and that MC therapy does not further improve the regenerative recovery, up to 12 weeks post lesion.