Scaling model checking of dataraces using dynamic information

Dataraces in multithreaded programs often indicate severe bugs and can cause unexpected behaviors when different thread interleavings are executed. Because dataraces are a cause for concern, many works have dealt with the problem of detecting them. Works based on dynamic techniques either report errors only for dataraces that occur in the current interleaving, which limits their usefulness, or produce many spurious dataraces. Works based on model checking search exhaustively for dataraces and thus can reveal even those that occur in rarely executed paths. However, the applicability of model checking is limited because the large number of thread interleavings in realistic multithreaded programs causes state space explosion. In this work, we combine the two techniques in a hybrid scheme which overcomes these difficulties and enjoys the advantages of both worlds. Our hybrid technique succeeds in providing thread interleavings that prove the existence of dataraces in realistic programs. The programs we experimented with cannot be checked using either an ordinary industrial strength model checker or bounded model checking.     

Proton-Conductive Melanin-Like Fibers through Enzymatic Oxidation of a Self-Assembling Peptide

Melanin pigments have various properties that are of technological interest including photo- and radiation protection, rich coloration, and electronic functions. Nevertheless, laboratory-based synthesis of melanin and melanin-like materials with morphologies and chemical structures that are specifically optimized for these applications, is currently not possible. Here, melanin-like materials that are produced by enzymatic oxidation of a supramolecular tripeptide structures that are rich in tyrosine and have a 1D morphology are demonstrated, that are retained during the oxidation process while conducting tracks form through oxidative tyrosine crosslinking. Specifically, a minimalistic self-assembling peptide, Lys–Tyr–Tyr (KYY) with strong propensity to form supramolecular fibers, is utilized. Analysis by Raman spectroscopy shows that the tyrosines are pre-organized inside these fibers and, upon enzymatic oxidation, result in connected catechols. These form 1D conducting tracks along the length of the fiber, which gives rise to a level of internal disorder, but retention of the fiber morphology. This results in highly conductive structures demonstrated to be dominated by proton conduction. This work demonstrates the ability to control oxidation but retain a well-defined fibrous morphology that does not have a known equivalent in biology, and demonstrate exceptional conductivity that is enhanced by enzymatic oxidation.     

Lubricating Medical Devices with Fullerene-Like Nanoparticles

In the present work, MoS₂ nanoparticles with fullerene-like structure, and most particularly those doped with minute amounts of rhenium atoms, are used as additive to medical gels in order to facilitate their entry into constricted openings of soft material rings. This procedure is used to mimic the entry of endoscopes to constricted openings of the human body, like urethra, etc. It is shown that the Re-doped nanoparticles reduce the traction force used to retrieve the metallic lead of the endoscope from the soft ring by a factor close to three times with respect to the original gel. The mechanism of the mitigation of both friction and adhesion forces in these systems by the nanoparticles is discussed.