Current status of automotive fuel cells for sustainable transport

Automotive proton-exchange membrane fuel cells (PEMFCs) have finally reached a state of technological readiness where several major automotive companies are commercially leasing and selling fuel cell electric vehicles, including Toyota, Honda, and Hyundai. These now claim vehicle speed and acceleration, refueling time, driving range, and durability that rival conventional internal combustion engines and in most cases outperform battery electric vehicles. The residual challenges and areas of improvement which remain for PEMFCs are performance at high current density, durability, and cost. These are expected to be resolved over the coming decade while hydrogen infrastructure needs to become widely available. Here, we briefly discuss the status of automotive PEMFCs, misconceptions about the barriers that platinum usage creates, and the remaining hurdles for the technology to become broadly accepted and implemented.     

Apis mellifera syriaca Venom: Evaluation of Its Anticoagulant Effect,Proteolytic Activity,and Cytotoxicity along with Its Two Main Compounds—MEL and PLA2—On HeLa Cancer Cells

Bee venom (BV) is one of the most remarkable natural products that has been a subject of studies since ancient times. Recent studies have shown that Apis mellifera syriaca venom possesses antibacterial as well as cytotoxic effects on cancer cell lines. The venom contains a variety of bioactive molecules—mainly melittin (MEL) and phospholipase A2 (PLA2), as well as other compounds that are not well characterized. In this work, we continue the biological characterization of A. mellifera syriaca venom by testing its anticoagulant effect on human plasma using the prothrombin time (PT) test, as well as assessing its proteolytic activity. In addition, the cytotoxicity of the crude venom—and of its two main components, MEL and PLA2—was tested on HeLa cancer cell lines for the first time. The results obtained showed the capacity of A. mellifera syriaca venom to increase clotting time, thereby proving its anticoagulant effect. Moreover, the venom did not demonstrate a significant proteolytic activity unless administrated at concentrations ≥ 5 mg/mL. Finally, we showed that crude A. mellifera syriaca venom, along with MEL, exhibit a strong in vitro cytotoxic effect on HeLa cancer cell lines, even at low concentrations. In summary, our findings could serve as a basis for the development of new natural-based drug candidates in the therapeutic field.     

Nonlinear effects in optical fibers

The basic differential equations necessary to represent nonlinear propagation of short and ultrashort optical pulses in dielectric waveguides are derived. After introducing fundamental and higher-order soliton solutions of the nonlinear Schroedinger equations, the possibilities of realizing soliton-based communication systems are discussed. Higher-order nonlinear effects associated with selj-Raman gain and optical amplification in connection with the use of active fibers are also described.     

Homogeneous and facially homogeneous self-dual cones

We show that any self-dual come in a real finite dimensional Hilbert space is homogeneous iff it is facially homogeneous in the sense of A. Connes. We develop a spectral decomposition theory for these cones which is the analogue of the usual one for self-adjoint operators on a finite-dimensional Hilbert space.     

Tweaking the acid-sensitivity of transiently thermoresponsive Polyacrylamides with cyclic acetal repeating units

Merging the characteristics of thermoresponsive and stimuli-degradable polymers yields so-called transiently thermoresponsive polymers, which can find application for the design of injectable gels, nanoparticles, etc. within a biomedical context. Among these polymers, only a limited number is reported which shows selective degradation under mild acidic conditions. However,extension of the library of transiently thermoresponsive polymers is desired to broadening the biomaterials toolbox to suit specific needs. Three monomers were developed by modification of 2-hydroxyethylacrylamide(HEAm) via tetrahydropyranylation or-furanylation with 3,4-dihydro-2 H-pyran(DHP), 2,3-dihydrofuran(DHF) or 2,3-dihydro-5-methylfuran(MeDHF). The presence of an acetal or ketal bond provided the monomers a pH-dependent hydrolysis behavior ranging from minutes to days. RAFT polymerisation allowed for the construction of homopolymers with temperature responsive behavior and pH-dependent hydrolysis which was strongly influenced by nature of the monomeric repeating units.     

Derivation of the Euler Equations from Quantum Dynamics

We derive the Euler equations from quantum dynamics for a class of fermionic many-body systems. We make two types of assumptions. The first type are physical assumptions on the solution of the Euler equations for the given initial data. The second type are a number of reasonable conjectures on the statistical mechanics and dynamics of the Fermion Hamiltonian.©2003 B. Nachtergaele and H.-T. Yau. This article may be reproduced in its entirety for non-commercial purposes.Research partially supported by NSF # DMS-0070774.Research partially supported by NSF # DMS-0072098, the Veblen Fund from the Institute for Advanced Study and a Fellowship from the MacArthur Foundation.