During the past two decades, diamond-like carbon (DLC) films have attracted an overwhelming interest from both industry and the research community. These films offer a wide range of exceptional physical, mechanical, biomedical and tribological properties that make them scientifically very fascinating and commercially essential for numerous industrial applications. Mechanically, certain DLC films are extremely hard (as hard as 90 GPa) and resilient, while tribologically they provide some of the lowest known friction and wear coefficients. Their optical and electrical properties are also extraordinary and can be tailored to meet the specific requirements of a given application. Because of their excellent chemical inertness, these films are resistant to corrosive and/or oxidative attacks in acidic and saline media. The combination of such a wide range of outstanding properties in one material is rather uncommon, so DLC can be very useful in meeting the multifunctional application needs of advanced mechanical systems. In fact, these films are now used in numerous industrial applications, including razor blades, magnetic hard discs, critical engine parts, mechanical face seals, scratch-resistant glasses, invasive and implantable medical devices and microelectromechanical systems. DLC films are primarily made of carbon atoms that are extracted or derived from carbon-containing sources, such as solid carbon targets and liquid and gaseous forms of hydrocarbons and fullerenes. Depending on the type of carbon source being used during the film deposition, the type of bonds (i.e. sp 1 ,s p 2 ,s p 3 ) that hold carbon atoms together in DLC may vary a great deal and can affect their mechanical, electrical, optical and tribological properties. Recent systematic studies of DLC films have confirmed that the presence or absence of certain elemental species, such as hydrogen, nitrogen, sulfur, silicon, tungsten, titanium and fluorine, in their microstructure can also play significant roles in their properties. The main goal of this review paper is to highlight the most recent developments in the synthesis, characterization and application of DLC films. We will also discuss the progress made in understanding the fundamental mechanisms that control their very unique friction and wear behaviours. Novel design concepts and the principles of superlubricity in DLC films are also presented. (Some figures in this article are in colour only in the electronic version)

https://iopscience.iop.org/article/10.1088/0022-3727/39/18/R01/pdf

Tribology of diamond-like carbon films: recent progress and future prospects

Advanced Therapeutic Dressings for Effective Wound Healing—A Review

Creating highly electrically conducting cables from macroscopic aggregates of carbon nanotubes, to replace metallic wires, is still a dream. Here we report the fabrication of iodine-doped, double-walled nanotube cables having electrical resistivity reaching ∼10−7 Ω.m. Due to the low density, their specific conductivity (conductivity/weight) is higher than copper and aluminum and is only just below that of the highest specific conductivity metal, sodium. The cables exhibit high current-carrying capacity of 104∼105 A/cm2 and can be joined together into arbitrary length and diameter, without degradation of their electrical properties. The application of such nanotube cables is demonstrated by partly replacing metal wires in a household light bulb circuit. The conductivity variation as a function of temperature for the cables is five times smaller than that for copper. The high conductivity nanotube cables could find a range of applications, from low dimensional interconnects to transmission lines.

/pdf/iodine-doped-carbon-nanotube-cables-exceeding-specific-mtpeduatun.pdf

Iodine doped carbon nanotube cables exceeding specific electrical conductivity of metals

Chemical, mechanical and tribological characterization of ultra-thin and hard amorphous carbon coatings as thin as 3.5 nm: recent developments

A review is presented of the studies in the former Soviet Union and in the USA of the mutual interactions of plasmas and high speed flows and shocks. There are reports from as early as the 1980s of large changes in the standoff distance ahead of a blunt body in ballistic tunnels, significantly reduced drag and modifications of travelling shocks in bounded weakly ionized gases. Energy addition to the flow results in an increase in the local sound speed that leads to expected modifications of the flow and changes to the pressure distribution around a vehicle due to the decrease in local Mach number. The critical question was, did a plasma provide a significant energy multiplier for the system? There have been a large number of experimental studies on the influence of a weakly ionized plasma on relatively low Mach number shocks and inherently also on the influence of the shock on the plasma. This literature is reviewed and illustrated with representative examples. The convergence through more controlled experiments and improved modelling to a physics understanding of the effects being essentially due to heating is outlined. It is demonstrated that the heating in many cases is global; however, tailored experiments with positive columns, dielectric barrier discharges and focused microwave plasmas can produce very localized heating. The latter appears more attractive for energy efficiency in flow control. Tailored localized ionization and thermal effects are also of interest for high speed inlet shock control and for producing reliable ignition for short residence time combustors, and work in these areas is also reviewed.

https://iopscience.iop.org/article/10.1088/0022-3727/38/4/R01/pdf

Plasmas in high speed aerodynamics

Despite the rapid progress being made in the synthesis of diamond films and recent interest in polishing of diamond films, no systematic measurements of friction and wear on polished diamond films have been reported. In the present study, chemomechanical and laser polishing techniques are used, and friction and wear data on the chemomechanically polished diamond films are presented. With the chemomechanical polishing technique used in this study, the rms roughness of hot filament chemical vapor deposited diamond films can be reduced from about 657 to about 170 nm with rounding off of sharp asperities with no change in the diamond structure. The polished films exhibit coefficient of friction (∼0.1) and wear rates much lower than that of unpolished films. Friction and wear properties of the polished films are comparable to that of single‐crystal natural diamond. Based on this study, it is concluded that polished films are potential candidates for tribological applications.

https://www.mecheng.osu.edu/netl/files/netl/TribologicalPropsPolishedDiamondFilm.pdf

Tribological properties of polished diamond films

Anti-TAG-72 monoclonal antibodies target the tumor-associated glycoprotein (TAG)-72 in various solid tumors. This study evaluated the use of anti-TAG-72 monoclonal antibodies, both murine CC49 and humanized CC49 (HuCC49deltaCH2), for near-infrared fluorescent (NIR) tumor imaging in colorectal cancer xenograft models. The murine CC49 and HuCC49deltaCH2 were conjugated with Cy7 monofunctional N-hydroxysuccinimide ester (Cy7-NHS). Both in vitro and in vivo anti-TAG-72 antibody binding studies were performed. The in vitro study utilized the human colon adenocarcinoma cell line LS174T that was incubated with Cy7, antibody-Cy7 conjugates, or excessive murine CC49 followed by the antibody-Cy7 conjugates and was imaged by fluorescence microscopy. The in vivo study utilized xenograft mice, bearing LS174T subcutaneous tumor implants, that received tail vein injections of Cy7, murine CC49-Cy7, HuCC49deltaCH2-Cy7, or nonspecific IgG-Cy7 and were imaged by the Xenogen IVIS 100 system from 15 min to 288 h. The biodistribution of the fluorescence labeled antibodies was determined by imaging the dissected tissues. The in vitro study revealed that the antibody-Cy7 conjugates bound to LS174T cells and were blocked by excessive murine CC49. The in vivo study demonstrated that murine CC49 achieved a tumor/blood ratio of 15 at 96 h postinjection. In comparison, HuCC49deltaCH2-Cy7 cleared much faster than murine CC49-Cy7 from the xenograft mice, and HuCC49deltaCH2-Cy7 achieved a tumor/blood ratio of 12 at 18 h postinjection. In contrast, Cy7 and Cy7 labeled nonspecific IgG resulted in no demonstrable tumor accumulation. When mice were injected with excessive unlabeled murine CC49 at 6 h before the injection of murine CC49-Cy7 or HuCC49deltaCH2-Cy7, both the intensity and retention time of the fluorescence from the tumor were reduced. In summary, the Cy7 labeled murine CC49 and HuCC49deltaCH2 demonstrate tumor-targeting capabilities in living colorectal cancer xenograft mice and provide an alternative modality for tumor imaging.

Near-Infrared Fluorescence Labeled Anti-TAG-72 Monoclonal Antibodies for Tumor Imaging in Colorectal Cancer Xenograft Mice

Exogenous application of an electric field can direct cell migration and improve wound healing; however clinical application of the therapy remains elusive due to lack of a suitable device and hence, limitations in understanding the molecular mechanisms. Here we report on a novel FDA approved redox-active Ag/Zn bioelectric dressing (BED) which generates electric fields. To develop a mechanistic understanding of how the BED may potentially influence wound re-epithelialization, we direct emphasis on understanding the influence of BED on human keratinocyte cell migration. Mapping of the electrical field generated by BED led to the observation that BED increases keratinocyte migration by three mechanisms: (i) generating hydrogen peroxide, known to be a potent driver of redox signaling, (ii) phosphorylation of redox-sensitive IGF1R directly implicated in cell migration, and (iii) reduction of protein thiols and increase in integrinαv expression, both of which are known to be drivers of cell migration. BED also increased keratinocyte mitochondrial membrane potential consistent with its ability to fuel an energy demanding migration process. Electric fields generated by a Ag/Zn BED can cross-talk with keratinocytes via redox-dependent processes improving keratinocyte migration, a critical event in wound re-epithelialization.

/pdf/improvement-of-human-keratinocyte-migration-by-a-redox-4pcwitus94.pdf

Improvement of human keratinocyte migration by a redox active bioelectric dressing.

Nonequilibrium vibrational kinetics of carbon monoxide at high translational mode temperatures

Shock propagation into weakly ionized gases shows several features differing markedly from conventional, nonionized-gas shock structure. Phenomenological analysis of general macroscopic features of the previously observed plasma shock effects allows only two possible interpretations: existence of an energy (momentum) flux toward the wave precursor or volumetric energy release (exothermic phase transition) in the upstream portion of the wave (precursor) followed by reverse transition in the downstream portion of the wave. It is shown that known microscopic mechanisms are not capable of producing such a flux or energy release: Typical processes involving electrons, ions, and excited species do not couple strongly to neutral atoms and molecules, and there is not enough energy stored in these species because of the low ionization fraction. The theoretical basis for phase transitions in low-density, weakly ionized plasmas also is unknown. Analysis of the steady two-wave system created by either of the two effects raises a question as to whether the observed plasma shocks are stable objects. Another question is whether there exists phase transition within the plasma shock. It also remains unclear to what extent twodimensional thermal inhomogeneity effects contribute to the observed phenomena. Answering these fundamental questions requires additional experimental studies of the problem. p D d E E/N F h j k

http://www.mecheng.osu.edu/netl/files/netl/netl/nological_Analysis_of_Shock_Wave_Propagation.pdf

Vish V. Subramaniam

Papers

Tribological properties of polished diamond films

Near-Infrared Fluorescence Labeled Anti-TAG-72 Monoclonal Antibodies for Tumor Imaging in Colorectal Cancer Xenograft Mice

Improvement of human keratinocyte migration by a redox active bioelectric dressing.

Nonequilibrium vibrational kinetics of carbon monoxide at high translational mode temperatures

Phenomenological Analysis of Shock-Wave Propagation in Weakly Ionized Plasmas