Combining Light Harvesting and Electron Transfer in Silica–Titania‐Based Organic–Inorganic Hybrid Materials

A convenient protocol to fabricate an organic–inorganic hybrid system with covalently bound light‐harvesting chromophores (stilbene and terphenylene–divinylene) and an electron acceptor (titanium oxide) is described. Efficient energy‐ and electron‐transfer processes may take place in these systems. Covalent bonding between the acceptor chromophores and the titania/silica matrix would be important for electron transfer, whereas fluorescence resonant energy transfer (FRET) would strongly depend on the ratio of donor to acceptor chromophores. Time‐resolved spectroscopy was employed to elucidate the detailed photophysical processes. The coupling of FRET and electron transfer was shown to work coherently to lead to photocurrent enhancement. The photocurrent responses reached a maximum when the hybrid‐material thin film contained 60 % acceptor and 40 % donor.     

Novel Strategy to Drive the Intracellular Uptake of Lipid Nanoparticles for Photodynamic Therapy

Nanoparticles’ uptake by cancer cells upon reaching the tumor microenvironment is often the rate-limiting step in cancer nanomedicine. Herein, we report that the inclusion of aminopolycarboxylic acid conjugated lipids, such as EDTA- or DTPA-hexadecylamide lipids in liposome-like porphyrin nanoparticles (PS) enhanced their intracellular uptake by 25-fold, which was attributed to these lipids’ ability to fluidize the cell membrane in a detergent-like manner rather than by metal chelation of EDTA or DTPA. EDTA-lipid-incorporated-PS (ePS) take advantage of its unique active uptake mechanism to achieve >95 % photodynamic therapy (PDT) cell killing compared to <5 % cell killing by PS. In multiple tumor models, ePS demonstrated fast fluorescence-enabled tumor delineation within minutes post-injection and increased PDT potency (100 % survival rate) compared to PS (60 %). This study offers a new nanoparticle cellular uptake strategy to overcome challenges associated with conventional drug delivery.     

Stereoconvergent,Redox‐Neutral Access to Tetrahydroquinoxalines through Relay Epoxide Opening/Amination of Alcohols

We present an economical catalytic procedure to convert readily available 1,2‐diaminobenzenes and terminal epoxides into valuable 1,2,3,4‐tetrahydroquinoxalines in a highly enantioselective fashion. This procedure operates through relay zinc and iridium catalysis, and achieves redox‐neutral and stereoconvergent production of valuable chiral heterocycles from racemic starting materials with water as the only side product. The use of commercially available reagents and catalysts and a convenient procedure also make this catalytic method attractive for practical application.     

Examples of Using 3D-GPC-TREF for Polyolefin Characterization

Summary: Selected examples of using 3D-GPC-TREF to solve polyolefin characterization problems are described in this paper. The term 3D-GPC-TREF stands for a home-build hybrid system of gel permeation chromatograph (GPC) coupled with the capability of the temperature rising elution fractionation (TREF) that includes three online detectors, i.e. the infrared (IR), the differential-pressure viscometer (DP), and the light scattering (LS) detectors.     

A Harnack inequality for Dirichlet eigenvalues

We prove a Harnack inequality for Dirichlet eigenfunctions of abelian homogeneous graphs and their convex subgraphs. We derive lower bounds for Dirichlet eigenvalues using the Harnack inequality. We also consider a randomization problem in connection with combinatorial games using Dirichlet eigenvalues. © 2000 John Wiley & Sons, Inc. J Graph Theory 34: 247–257, 2000     

Determination of antioxidants in polyolefins using total dissolution methodology followed by RPLC

Antioxidants are added to polyolefins to improve the stability of the resin from oxidation and degradation during processing of the finished article and to increase product lifetime. Without antioxidants, polyolefins would quickly degrade during and after the extrusion or thermoforming process, which would cause inferior appearance and physical properties. The proper level must be added to protect the polymer and to minimize cost. Antioxidants are usually extracted from the resin and the extract is analyzed by RPLC, GC, or Fourier transform infrared spectroscopy. Unfortunately, many of these procedures require significant manual labor, time, and solvent, rendering them impractical for high-throughput work processes. In addition, they may not provide complete extraction of the additives depending upon the type of resin. A validated analytical method was needed for the determination of three common antioxidants, Irganox(?) 1010, Irganox(?) 1076, and Irgafos(?) 168 in polyolefin resins. This paper shows the determination of these antioxidants using dissolution followed by precipitation with o-xylene and methanol. Direct analysis of the solution is achieved in 8?min using RPLC.     

On the utility of graphics cards to perform massively parallel simulation of advanced Monte Carlo methods

We present a case-study on the utility of graphics cards to perform massively parallel simulation of advanced Monte Carlo methods. Graphics cards, containing multiple Graphics Processing Units (GPUs), are self-contained parallel computational devices that can be housed in conventional desktop and laptop computers and can be thought of as prototypes of the next generation of many-core processors. For certain classes of population-based Monte Carlo algorithms they offer massively parallel simulation, with the added advantage over conventional distributed multi-core processors that they are cheap, easily accessible, easy to maintain, easy to code, dedicated local devices with low power consumption. On a canonical set of stochastic simulation examples including population-based Markov chain Monte Carlo methods and Sequential Monte Carlo methods, we nd speedups from 35 to 500 fold over conventional single-threaded computer code. Our findings suggest that GPUs have the potential to facilitate the growth of statistical modelling into complex data rich domains through the availability of cheap and accessible many-core computation. We believe the speedup we observe should motivate wider use of parallelizable simulation methods and greater methodological attention to their design.     

A Rigorous Treatment of Energy Extraction from a Rotating Black Hole

The Cauchy problem is considered for the scalar wave equation in the Kerr geometry. We prove that by choosing a suitable wave packet as initial data, one can extract energy from the black hole, thereby putting supperradiance, the wave analogue of the Penrose process, into a rigorous mathematical framework. We quantify the maximal energy gain. We also compute the infinitesimal change of mass and angular momentum of the black hole, in agreement with Christodoulou’s result for the Penrose process. The main mathematical tool is our previously derived integral representation of the wave propagator. Research supported in part by the Deutsche Forschungsgemeinschaft. Research supported by NSERC grant # RGPIN 105490-2004. Research supported in part by the Humboldt Foundation and the National Science Foundation, Grant No. DMS-0603754. Research supported in part by the NSF, Grant No. 33-585-7510-2-30.     

Local Geometry of the <Emphasis Type="Italic">G</Emphasis><Subscript>2</Subscript> Moduli Space

We consider deformations of torsion-free G ₂ structures, defined by the G ₂-invariant 3-form φ and compute the expansion of \({\ast \varphi }\) to fourth order in the deformations of φ. By considering M-theory compactified on a G ₂ manifold, the G ₂ moduli space is naturally complexified, and we get a Kähler metric on it. Using the expansion of \({\ast \varphi }\), we work out the full curvature of this metric and relate it to the Yukawa coupling.     

Suspended bridges subjected to moving loads and support motions due to earthquake

The paper deals with the vibration of suspended bridges subjected to the simultaneous action of moving loads and vertical support motions due to earthquake. The basic partial integro-differential equation is applied to the vertical vibration of a suspended beam. The dynamic actions of traffic loads are modelled as a row of equidistant moving forces, while the earthquake is considered by vertical motions of supports. The governing equation is solved first analytically to receive an ordinary differential equation and next numerically. Moreover, the designed world's largest suspended bridge—Messina Bridge—is investigated (central span of length 3.3 km). The paper studies the effect of various lags of the earthquake arrival because the earthquake may appear at any time when the train moves along a large-span bridge. The modified Kobe earthquake records have been applied to calculations. The results indicate that the interaction of both the moving and seismic forces may substantially amplify the response of long-span suspended bridges in the vicinity of the supports and increase with the rising speed of trains.