Synthesis and characterization of one-dimensional flat ZnO nanotower arrays as high-efficiency adsorbents for the photocatalytic remediation of water pollutants.

We report on facile fabrication of 1-D flat ZnO nanotower arrays on various substrates, including a metal, a semiconductor and an insulator. The nanotowers have a unique flat basal section near the substrate and taper in stages to wire-like at the tip. Electron microscopy and X-ray photoelectron spectroscopy are used to characterize these new nanostructures, revealing that their morphologies are significantly influenced by reaction temperature.

At the edge of translation - materials to program cells for directed differentiation.

Oral Diseases (2011) 17, 241-251 The rapid advancement in basic biology knowledge, especially in the stem cell field, has created new opportunities to develop biomaterials capable of orchestrating the behavior of transplanted and host cells. Based on our current understanding of cellular differentiation, a conceptual framework for the use of materials to program cells in situ is presented, namely a domino vs a switchboard model, to highlight the use of single vs multiple cues in a controlled manner to modulate biological processes. Further, specific design principles of material systems to present soluble and insoluble cues that are capable of recruiting, programming and deploying host cells for various applications are presented.

Force Tracking with Feed-Forward Motion Estimation for Beating Heart Surgery.

The manipulation of fast moving, delicate tissues in beating heart procedures presents a considerable challenge to the surgeon. A robotic force tracking system can assist the surgeon by applying precise contact forces to the beating heart during surgical manipulation. Standard force control approaches cannot safely attain the required bandwidth for this application due to vibratory modes within the robot structure.

Robotic tissue tracking for beating heart mitral valve surgery.

The rapid motion of the heart presents a significant challenge to the surgeon during intracardiac beating heart procedures. We present a 3D ultrasound-guided motion compensation system that assists the surgeon by synchronizing instrument motion with the heart. The system utilizes the fact that certain intracardiac structures, like the mitral valve annulus, have trajectories that are largely constrained to translation along one axis.

Nanoglycan complex formulation extends VEGF retention time in the lung.

To extend the retention time of aerosol-delivered growth factors in the lung for stem cell homing/activation purposes, we examined a formulation of vascular endothelial growth factor (VEGF) complexed to dextran sulfate (DS) and chitosan (CS) polyelectrolytes. Optimal incorporation of VEGF was found at a VEGF/DS/CS ratio of 0.12:1:0.

Mitral annulus segmentation from 3D ultrasound using graph cuts.

The shape of the mitral valve annulus is used in diagnostic and modeling applications, yet methods to accurately and reproducibly delineate the annulus are limited. This paper presents a mitral annulus segmentation algorithm designed for closed mitral valves which locates the annulus in three-dimensional ultrasound using only a single user-specified point near the center of the valve. The algorithm first constructs a surface at the location of the thin leaflets, and then locates the annulus by finding where the thin leaflet tissue meets the thicker heart wall.

Immunologically active biomaterials for cancer therapy.

Our understanding of immunological regulation has progressed tremendously alongside the development of materials science, and at their intersection emerges the possibility to employ immunologically active biomaterials for cancer immunotherapy. Strong and sustained anticancer, immune responses are required to clear large tumor burdens in patients, but current approaches for immunotherapy are formulated as products for delivery in bolus, which may be indiscriminate and/or shortlived. Multifunctional biomaterial particles are now being developed to target and sustain antigen and adjuvant delivery to dendritic cells in vivo, and these have the potential to direct and prolong antigen-specific T cell responses.

Promotion of Mn(II) oxidation and remediation of coal mine drainage in passive treatment systems by diverse fungal and bacterial communities.

Biologically active, passive treatment systems are commonly employed for removing high concentrations of dissolved Mn(II) from coal mine drainage (CMD). Studies of microbial communities contributing to Mn attenuation through the oxidation of Mn(II) to sparingly soluble Mn(III/IV) oxide minerals, however, have been sparse to date. This study reveals a diverse community of Mn(II)-oxidizing fungi and bacteria existing in several CMD treatment systems.

Design and Control of Motion Compensation Cardiac Catheters.

Robotic cardiac catheters have the potential to revolutionize heart surgery by extending minimally invasive techniques to complex surgical repairs inside the heart. However, catheter technologies are currently unable to track fast tissue motion, which is required to perform delicate procedures inside a beating heart. This paper proposes an actuated catheter tool that compensates for the motion of heart structures like the mitral valve apparatus by servoing a catheter guidewire inside a flexible sheath.

Robotic Force Stabilization for Beating Heart Intracardiac Surgery.

The manipulation of fast moving, delicate tissues in beating heart procedures presents a considerable challenge to surgeons. We present a new robotic force stabilization system that assists surgeons by maintaining a constant contact force with the beating heart. The system incorporates a novel, miniature uniaxial force sensor that is mounted to surgical instrumentation to measure contact forces during surgical manipulation.

Ultrahigh-throughput screening in drop-based microfluidics for directed evolution.

The explosive growth in our knowledge of genomes, proteomes, and metabolomes is driving ever-increasing fundamental understanding of the biochemistry of life, enabling qualitatively new studies of complex biological systems and their evolution. This knowledge also drives modern biotechnologies, such as molecular engineering and synthetic biology, which have enormous potential to address urgent problems, including developing potent new drugs and providing environmentally friendly energy. Many of these studies, however, are ultimately limited by their need for even-higher-throughput measurements of biochemical reactions.

Primitives for motor adaptation reflect correlated neural tuning to position and velocity.

The motor commands required to control voluntary movements under various environmental conditions may be formed by adaptively combining a fixed set of motor primitives. Since this motor output must contend with state-dependent physical dynamics during movement, these primitives are thought to depend on the position and velocity of motion. Using a recently developed "error-clamp" technique, we measured the fine temporal structure of changes in motor output during adaptation.

Soft colloids make strong glasses.

Glass formation in colloidal suspensions has many of the hallmarks of glass formation in molecular materials. For hard-sphere colloids, which interact only as a result of excluded volume, phase behaviour is controlled by volume fraction, phi; an increase in phi drives the system towards its glassy state, analogously to a decrease in temperature, T, in molecular systems. When phi increases above phi* approximately 0.

Cyclic tensile strain triggers a sequence of autocrine and paracrine signaling to regulate angiogenic sprouting in human vascular cells.

Mechanical signals regulate blood vessel development in vivo, and have been demonstrated to regulate signal transduction of endothelial cell (EC) and smooth muscle cell (SMC) phenotype in vitro. However, it is unclear how the complex process of angiogenesis, which involves multiple cell types and growth factors that act in a spatiotemporally regulated manner, is triggered by a mechanical input. Here, we describe a mechanism for modulating vascular cells during sequential stages of an in vitro model of early angiogenesis by applying cyclic tensile strain.

An active biopolymer network controlled by molecular motors.

We describe an active polymer network in which processive molecular motors control network elasticity. This system consists of actin filaments cross-linked by filamin A (FLNa) and contracted by bipolar filaments of muscle myosin II. The myosin motors stiffen the network by more than two orders of magnitude by pulling on actin filaments anchored in the network by FLNa cross-links, thereby generating internal stress.

Constitutive modeling of porcine liver in indentation using 3D ultrasound imaging.

In this work we present an inverse finite-element modeling framework for constitutive modeling and parameter estimation of soft tissues using full-field volumetric deformation data obtained from 3D ultrasound. The finite-element model is coupled to full-field visual measurements by regularization springs attached at nodal locations. The free ends of the springs are displaced according to the locally estimated tissue motion, and the normalized potential energy stored in all springs serves as a measure of model-experiment agreement for material parameter optimization.

From crater functions to partial differential equations: a new approach to ion bombardment induced nonequilibrium pattern formation.

We develop a methodology for deriving continuum partial differential equations for the evolution of large-scale surface morphology directly from molecular dynamics simulations of the craters formed from individual ion impacts. Our formalism relies on the separation between the length scale of ion impact and the characteristic scale of pattern formation, and expresses the surface evolution in terms of the moments of the crater function. We demonstrate that the formalism reproduces the classical Bradley-Harper results, as well as ballistic atomic drift, under the appropriate simplifying assumptions.

Linear stability and instability patterns in ion-sputtered silicon.

We study the patterns formed on Ar(+) ion-sputtered Si surfaces at room temperature as a function of the control parameters ion energy and incidence angle. We observe the sensitivity of pattern formation to artifacts such as surface contamination and report the procedures we developed to control them. We identify regions in control parameter space where holes, parallel mode ripples and perpendicular mode ripples form, and identify a region where the flat surface is stable.

Microstructural effects on electrical conductivity relaxation in nanoscale ceria thin films.

Microstructure evolution and electrical conductivity relaxation kinetics in highly textured and nanocrystalline dense ceria thin films (approximately 65 nm) are reported in this paper. Highly textured films were grown on sapphire c-plane substrates by molecular beam synthesis (MBS) with orientation relationship (111)CeO(2)parallel(0001)Al(2)O(3) and [110]CeO(2)parallel[1210]Al(2)O(3). No significant structural changes were observed in highly textured films even after extensive annealing at high temperature.

Formulation and pharmacokinetics of self-assembled rifampicin nanoparticle systems for pulmonary delivery.

Purpose: To formulate rifampicin, an anti-tuberculosis antibiotic, for aerosol delivery in a dry powder 'porous nanoparticle-aggregate particle' (PNAP) form suited for shelf stability, effective dispersibility and extended release with local lung and systemic drug delivery.

Methods: Rifampicin was encapsulated in PLGA nanoparticles by a solvent evaporation process, spray dried into PNAPs containing varying amounts of nanoparticles, and characterized for physical and aerosol properties. Pharmacokinetic studies were performed with formulations delivered to guinea pigs by intratracheal insufflation and compared to oral and intravenous delivery of rifampicin.

Atomistic simulation of field enhanced oxidation of Al (100) beyond the mott potential.

Molecular dynamics simulations employing dynamic charge transfer between atoms indicate a significantly enhanced rate of Al(100) oxidation by O2 and O at 300 K in the presence of an electric field. Increasing the electric field (approximately 10(7) V/cm) drives the surface chemisorbed oxygen to the vacancy sites in the oxide interior leading to dramatic density and stoichiometry improvements of the grown ultrathin oxide film. The associated oxidation kinetics enhancement due to the applied electric field is postulated to arise from the activation barrier lowering at electrostatic potentials approaching the Mott potential and beyond, leading to a dramatically increased ion migration through oxide film.

Dry powder nitroimidazopyran antibiotic PA-824 aerosol for inhalation.

We formulated PA-824, a nitroimidazopyran with promise for the treatment of tuberculosis, for efficient aerosol delivery to the lungs in a dry powder porous particle form. The objectives of this study were to prepare and characterize a particulate form of PA-824, assess the stability of this aerosol formulation under different environmental conditions, and determine the pharmacokinetic parameters for the powder after pulmonary administration. The drug was spray dried into porous particles containing a high drug load and possessing desirable aerosol properties for efficient deposition in the lungs.

Mitral Annulus Segmentation from Three-Dimensional Ultrasound.

An accurate and reproducible segmentation of the mitral valve annulus from 3D ultrasound is useful to clinicians and researchers in applications such as pathology diagnosis and mitral valve modeling. Current segmentation methods, however, are based on 2D information, resulting in inaccuracies and a lack of spatial coherence. We present a segmentation algorithm which, given a single user-specified point near the center of the valve, uses max-flow and active contour methods to delineate the annulus geometry in 3D.

Robotic force stabilization for beating heart intracardiac surgery.

The manipulation of fast moving, delicate tissues in beating heart procedures presents a considerable challenge to surgeons. We present a new robotic force stabilization system that assists surgeons by maintaining a constant contact force with the beating heart. The system incorporates a novel, miniature uniaxial force sensor that is mounted to surgical instrumentation to measure contact forces during surgical manipulation.