Choice of a hemodynamic model for occlusive thrombosis in arteries.

Intravascular thrombosis can lead to heart attacks and strokes that together are the leading causes of death in the US (Kochanek, K.D., Murphy, S.

Rheological Study and Molecular Dynamics Simulation of Biopolymer Blend Thermogels of Tunable Strength.

The temperature-induced gelation of chitosan/glycerophosphate (Chs/GP) systems through physical interactions has shown great potential for various biomedical applications. In the present work, hydroxyethyl cellulose (HEC) was added to the thermosensitive Chs/GP solution to improve the mechanical strength and gel properties of the incipient Chs/HEC/GP gel in comparison with the Chs/GP hydrogel at body temperature. The physical features of the macromolecular complexes formed by the synergistic interaction between chitosan and hydroxyethyl cellulose in the presence of β-glycerophosphate disodium salt solution have been studied essentially from a rheological point of view.

Cellular Stiffness as a Novel Stemness Marker in the Corneal Limbus.

Healthy eyes contain a population of limbal stem cells (LSCs) that continuously renew the corneal epithelium. However, each year, 1 million Americans are afflicted with severely reduced visual acuity caused by corneal damage or disease, including LSC deficiency (LSCD). Recent advances in corneal transplant technology promise to repair the cornea by implanting healthy LSCs to encourage regeneration; however, success is limited to transplanted tissues that contain a sufficiently high percentage of LSCs.

Novel reverse osmosis membranes composed of modified PVA/Gum Arabic conjugates: Biofouling mitigation and chlorine resistance enhancement.

A novel crosslinked Poly (vinyl alcohol) (PVA) reverse osmosis (RO) thin film membrane conjugated with Gum Arabic (GA) with superb performance and features was synthesized for water desalination. RO membrane desalination parameters, such as hydrophilicity, surface roughness, water permeability, salt rejection, Chlorine resistance and biofouling resistance were evaluated using a dead end RO filtration unit. The incorporation of Pluronic F127 and the conjugation of Gum Arabic improved the overall RO performance of the membranes.

Optical method for automated measurement of glass micropipette tip geometry.

Many experimental biological techniques utilize hollow glass needles called micropipettes to perform fluid extraction, cell manipulation, and electrophysiological recordings For electrophysiological recordings, micropipettes are typically fabricated immediately before use using a "pipette puller", which uses open-loop control to heat a hollow glass capillary while applying a tensile load. Variability between manufactured micropipettes requires a highly trained operator to qualitatively inspect each micropipette; typically this is achieved by viewing the pipette under 40-100x magnification in order to ensure that the tip has the correct shape (e.g.

A flexible method for the preparation of thin film samples for in situ TEM characterization combining shadow-FIB milling and electron-beam-assisted etching.

A new method for the preparation of freestanding thin film samples for mechanical testing in transmission electron microscopes is presented. It is based on a combination of focused ion beam (FIB) milling and electron-beam-assisted etching with xenon difluoride (XeF) precursor gas. The use of the FIB allows for the target preparation of microstructural defects and enables well-defined sample geometries which can be easily adapted in order to meet the requirements of various testing setups.

Electromagnetic Fields and Stem Cell Fate: When Physics Meets Biology.

Controlling stem cell (SC) fate is an extremely important topic in the realm of SC research. A variety of different external cues mainly mechanical, chemical, or electrical stimulations individually or in combination have been incorporated to control SC fate. Here, we will deconstruct the probable relationship between the functioning of electromagnetic (EMF) and SC fate of a variety of different SCs.

Understanding biophysical behaviours of microfluidic-synthesized nanoparticles at nano-biointerface.

Encapsulating drugs in nanoparticles (NPs) provide some advantages over free drugs; for example the probability of distribution in off-target tissues decreases and drugs remain safe from environment degrading factors. Upon entering the bioenvironment, NPs establish a number of interactions with their surroundings based on their physicochemical properties. Here we demonstrate how the size-surface charge interplay of chitosan NPs affects the protein corona formation and endocytosis pathway in the HeLa cells at non-toxic concentrations.

Spatial Engineering of Osteochondral Tissue Constructs Through Microfluidically Directed Differentiation of Mesenchymal Stem Cells.

The development of tissue engineered osteochondral units has been slowed by a number of technical hurdles associated with recapitulating their heterogeneous nature ex vivo. Subsequently, numerous approaches with respect to cell sourcing, scaffolding composition, and culture media formulation have been pursued, which have led to high variability in outcomes and ultimately the lack of a consensus bioprocessing strategy. As such, the objective of this study was to standardize the design process by focusing on differentially supporting formation of cartilaginous and bony matrix by a single cell source in a spatially controlled manner within a single material system.

Uncovering Special Nuclear Materials by Low-energy Nuclear Reaction Imaging.

Weapons-grade uranium and plutonium could be used as nuclear explosives with extreme destructive potential. The problem of their detection, especially in standard cargo containers during transit, has been described as "searching for a needle in a haystack" because of the inherently low rate of spontaneous emission of characteristic penetrating radiation and the ease of its shielding. Currently, the only practical approach for uncovering well-shielded special nuclear materials is by use of active interrogation using an external radiation source.

Quantifying and observing viscoplasticity at the nanoscale: highly localized deformation mechanisms in ultrathin nanocrystalline gold films.

This study unveils the stress relaxation transient deformation mechanisms in 100 nm-thick, nanocrystalline Au films thanks to a robust quantitative in situ TEM MEMS nanomechanical testing approach to quantify stress relaxation and to perform in situ observations of time-dependent deformation in ultrathin nanocrystalline films. The relaxation is characterized by a decrease in plastic strain rate of more than one order of magnitude over the first ∼30 minutes (from 10(-4) to less than 10(-5) s(-1)). For longer relaxation experiments, the plastic strain rate decreases down to 10(-7) s(-1) after several hours.

Microfluidic Manipulation of Core/Shell Nanoparticles for Oral Delivery of Chemotherapeutics: A New Treatment Approach for Colorectal Cancer.

A microfluidics approach to synthesize core-shell nanocarriers with high pH tunability is described. The sacrificial shell protects the core layer with the drugs and prevents their release in the severe pH conditions of the gastrointestinal tract, while allowing for drug release in the proximity of a tumor. The proposed nanoparticulate drug-delivery system is designed for the oral administration of cancer therapeutics.

Hydrodynamic loading in concomitance with exogenous cytokine stimulation modulates differentiation of bovine mesenchymal stem cells towards osteochondral lineages.

Background: Mesenchymal stem cells (MSCs) are viewed as a having significant potential for tissue engineering and regenerative medicine therapies. Clinical implementation of MSCs, however, demands that their preparation be stable and reproducible. Given that environmental and bioprocessing parameters such as substrate stiffness, seeding densities, culture medium composition, and mechanical loading can result in undirected differentiation of the MSC population, the objective of this study was to systematically investigate how hydrodynamic loading influences the differentiation of bone marrow-derived mesenchymal stem cells (MSCs) towards the osteochondral lineages both in the presence and absence of exogenous, inductive factors.

First-Principles Density Functional Theory Modeling of Li Binding: Thermodynamics and Redox Properties of Quinone Derivatives for Lithium-Ion Batteries.

The Li-binding thermodynamics and redox potentials of seven different quinone derivatives are investigated to determine their suitability as positive electrode materials for lithium-ion batteries. First, using density functional theory (DFT) calculations on the interactions between the quinone derivatives and Li atoms, we find that the Li atoms primarily bind with the carbonyl groups in the test molecules. Next, we observed that the redox properties of the quinone derivatives can be tuned in the desired direction by systematically modifying their chemical structures using electron-withdrawing functional groups.

Phonon transport at the interfaces of vertically stacked graphene and hexagonal boron nitride heterostructures.

Hexagonal boron nitride (h-BN) is a promising substrate for graphene based nano-electronic devices. We investigate the ballistic phonon transport at the interface of vertically stacked graphene and h-BN heterostructures using first principles density functional theory and atomistic Green's function simulations considering the influence of lattice stacking. We compute the frequency and wave-vector dependent transmission function and observe distinct stacking-dependent phonon transmission features for the h-BN/graphene/h-BN sandwiched systems.

Sparse wavefield reconstruction and source detection using Compressed Sensing.

The paper presents a Compressed Sensing technique for the reconstruction of guided wavefields. Structural inspections based on the analysis of guided wavefields have proven to be effective at detecting and characterizing damage. However, wavefield detection is often a time consuming process, which limits practicality.

System for Rapid, Precise Modulation of Intraocular Pressure, toward Minimally-Invasive In Vivo Measurement of Intracranial Pressure.

Pathologic changes in intracranial pressure (ICP) are commonly observed in a variety of medical conditions, including traumatic brain injury, stroke, brain tumors, and glaucoma. However, current ICP measurement techniques are invasive, requiring a lumbar puncture or surgical insertion of a cannula into the cerebrospinal fluid (CSF)-filled ventricles of the brain. A potential alternative approach to ICP measurement leverages the unique anatomy of the central retinal vein, which is exposed to both intraocular pressure (IOP) and ICP as it travels inside the eye and through the optic nerve; manipulating IOP while observing changes in the natural pulsations of the central retinal vein could potentially provide an accurate, indirect measure of ICP.

Conjugation of silica nanoparticles with cellulose acetate/polyethylene glycol 300 membrane for reverse osmosis using MgSO4 solution.

Thermally-induced phase separation (TIPS) method was used to synthesize polymer matrix (PM) membranes for reverse osmosis from cellulose acetate/polyethylene glycol (CA/PEG300) conjugated with silica nanoparticles (SNPs). Experimental data showed that the conjugation of SNPs changed the surface properties as dense and asymmetric composite structure. The results were explicitly determined by the permeability flux and salt rejection efficiency of the PM-SNPs membranes.

Thermal Transport in Fullerene Derivatives Using Molecular Dynamics Simulations.

In order to study the effects of alkyl chain on the thermal properties of fullerene derivatives, we perform molecular dynamics (MD) simulations to predict the thermal conductivity of fullerene (C60) and its derivative phenyl-C61-butyric acid methyl ester (PCBM). The results of non-equilibrium MD simulations show a length-dependent thermal conductivity for C60 but not for PCBM. The thermal conductivity of C60, obtained from the linear extrapolation of inverse conductivity vs.

Inspection of notch depths in thin structures using transmission coefficients of laser-generated Lamb waves.

The non-contact feature of the Laser/EMAT ultrasonic (LEU) technique is attractive for its NDT applications. However, it is challenging to apply it in thin structures because of the difficulties in the signal interpretations. In this work, the LEU technique is used to inspect the notch depths in thin steel plates.

Spatially Resolved Probing of Electrochemical Reactions via Energy Discovery Platforms.

The electrochemical reactivity of solid surfaces underpins functionality of a broad spectrum of materials and devices ranging from energy storage and conversion, to sensors and catalytic devices. The surface electrochemistry is, however, a complex process, controlled by the interplay of charge generation, field-controlled and diffusion-controlled transport. Here we explore the fundamental mechanisms of electrochemical reactivity on nanocrystalline ceria, using the synergy of nanofabricated devices and time-resolved Kelvin probe force microscopy (tr-KPFM), an approach we refer to as energy discovery platform.

Invited Review Article: Error and uncertainty in Raman thermal conductivity measurements.

Error and uncertainty in Raman thermal conductivity measurements are investigated via finite element based numerical simulation of two geometries often employed—Joule-heating of a wire and laser-heating of a suspended wafer. Using this methodology, the accuracy and precision of the Raman-derived thermal conductivity are shown to depend on (1) assumptions within the analytical model used in the deduction of thermal conductivity, (2) uncertainty in the quantification of heat flux and temperature, and (3) the evolution of thermomechanical stress during testing. Apart from the influence of stress, errors of 5% coupled with uncertainties of ±15% are achievable for most materials under conditions typical of Raman thermometry experiments.

Enhanced osteogenic differentiation of stem cells via microfluidics synthesized nanoparticles.

Unlabelled: Advancement of bone tissue engineering as an alternative for bone regeneration has attracted significant interest due to its potential in reducing the costs and surgical trauma affiliated with the effective treatment of bone defects. We have improved the conventional approach of producing polymeric nanoparticles, as one of the most promising choices for drug delivery systems, using a microfluidics platform, thus further improving our control over osteogenic differentiation of mesenchymal stem cells. Molecular dynamics simulations were carried out for theoretical understanding of our experiments in order to get a more detailed molecular-scale insight into the drug-carrier interactions.

Lift forces on colloidal particles in combined electroosmotic and Poiseuille flow.

Colloidal particles suspended in aqueous electrolyte solutions flowing through microchannels are subject to lift forces that repel the particles from the wall due to the voltage and pressure gradients commonly used to drive flows in microfluidic devices. There are very few studies that have considered particles subject to both an electric field and a pressure gradient, however. Evanescent-wave particle tracking velocimetry was therefore used to investigate the near-wall dynamics of a dilute suspension of 245 nm radius polystyrene particles in a monovalent electrolyte solution in Poiseuille and combined electroosmotic (EO) and Poiseuille flow through 30-μm-deep fused-silica channels.