Structure and belonging: Pathways to success for underrepresented minority and women PhD students in STEM fields.

The advancement of underrepresented minority and women PhD students to elite postdoctoral and faculty positions in the STEM fields continues to lag that of majority males, despite decades of efforts to mitigate bias and increase opportunities for students from diverse backgrounds. In 2015, the National Science Foundation Alliance for Graduate Education and the Professoriate (NSF AGEP) California Alliance (Berkeley, Caltech, Stanford, UCLA) conducted a wide-ranging survey of graduate students across the mathematical, physical, engineering, and computer sciences in order to identify levers to improve the success of PhD students, and, in time, improve diversity in STEM leadership positions, especially the professoriate. The survey data were interpreted via path analysis, a method that identifies significant relationships, both direct and indirect, among various factors and outcomes of interest.

Digital microfluidics for spheroid-based invasion assays.

Cell invasion is a key process in tissue growth, wound healing, and tumor progression. Most invasion assays examine cells cultured in adherent monolayers, which fail to recapitulate the three-dimensional nuances of the tissue microenvironment. Multicellular cell spheroids have a three-dimensional (3D) morphology and mimic the intercellular interactions found in tissues in vivo, thus providing a more physiologically relevant model for studying the tissue microenvironment and processes such as cell invasion.

Digital microfluidics for automated hanging drop cell spheroid culture.

Cell spheroids are multicellular aggregates, grown in vitro, that mimic the three-dimensional morphology of physiological tissues. Although there are numerous benefits to using spheroids in cell-based assays, the adoption of spheroids in routine biomedical research has been limited, in part, by the tedious workflow associated with spheroid formation and analysis. Here we describe a digital microfluidic platform that has been developed to automate liquid-handling protocols for the formation, maintenance, and analysis of multicellular spheroids in hanging drop culture.

Fluorinated liquid-enabled protein handling and surfactant-aided crystallization for fully in situ digital microfluidic MALDI-MS analysis.

A droplet (digital) microfluidic device has been developed that enables complete protein sample preparation for MALDI-MS analysis. Protein solution dispensing, disulfide bond reduction and alkylation, tryptic digestion, sample crystallization, and mass spectrometric analysis are all performed on a single device without the need for any ex situ sample purification. Fluorinated solvents are used as an alternative to surfactants to facilitate droplet movement and limit protein adsorption onto the device surface.

Thiol-ene click reaction as a general route to functional trialkoxysilanes for surface coating applications.

Functionalized trialkoxysilanes are widely used to modify the surface properties of materials and devices. It will be shown that the photoinitiated radical-based thiol-ene "click" reaction provides a simple and efficient route to diverse trialkoxysilanes. A total of 15 trialkoxysilanes were synthesized by reacting either alkenes with 3-mercaptopropyltrialkoxysilane or thiols with allyltrialkoxysilanes in the presence of a photoinitiator.

Closing the immunization gap.

Current vaccination rates are falling with a new group of unimmunized children. Since some parents are unaware of the diseases and potential health threats, many are often influenced by the media and myths, choosing to delay or avoid vaccinations. NP providers must be prepared to confront these myths with facts to help parents make informed decisions.

Polymerization of electric field-centered double emulsion droplets to create polyacrylate shells.

Porous and hollow particles are widely used in pharmaceuticals, as solid phases for chromatography, as catalyst supports, in bioanalytical assays and medical diagnostics, and in many other applications. By controlling size, shape, and chemistry, it is possible to tune the physical and chemical properties of the particles. In some applications of millimeter-scale hollow shells, such as in high energy density physics, controlling the shell thickness uniformity (concentricity) and roundness (sphericity) becomes particularly important.

Incubated protein reduction and digestion on an electrowetting-on-dielectric digital microfluidic chip for MALDI-MS.

Localized heating of droplets on an electrowetting-on-dielectric (EWOD) chip has been implemented and shown to accelerate trypsin digestion reaction rates, sample drying, and matrix crystallization for matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). Achieving this involved extending the functionality of previous EWOD droplet-based techniques by developing a multifunctional electrode with closed-loop temperature control, while minimizing overall system complexity and addressing challenges associated with rapid evaporation. For the EWOD chip design, we discuss the performance of multifunctional surface electrodes for actuation, localized Joule heating, and thermistic temperature sensing.

Attitudes and practices of resident physicians regarding hypertension in the inpatient setting.

Hypertension is prevalent in the population at large and among hospitalized patients. Little has been reported regarding the attitudes and patterns of care of physicians managing nonemergent elevated blood pressure (BP) among inpatients. Resident physicians in internal medicine (IM), family medicine (FM), and surgery were surveyed regarding inpatient BP management.

Simple preparation and application of TEMPO-coated Fe(3)O(4) superparamagnetic nanoparticles for selective oxidation of alcohols.

The organic oxidant TEMPO (2,2,4,4-tetramethylpiperdine-1-oxyl) was immobilized on iron oxide (Fe(3)O(4)) superparamagnetic nanoparticles by employing strong metal-oxide chelating phosphonates and azide/alkyne "click" chemistry. This simple preparation yields recyclable TEMPO-coated nanoparticles with good TEMPO loadings. They have excellent magnetic response and efficiently catalyze the oxidation of a wide range of primary and secondary alcohols to aldehydes, ketones, and lactones under either aerobic acidic Mn(II)/Cu(II) oxidizing Minisci conditions, or basic NaOCl Anelli conditions.

Integration of protein processing steps on a droplet microfluidics platform for MALDI-MS analysis.

A droplet-based (digital) microfluidics platform has been developed to prepare and purify protein samples for measurement by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Liquid droplets are moved in air by sequentially applying an electric potential to an array of electrodes patterned beneath a hydrophobic dielectric layer. We show that a complete integrated sequence of protein processing steps can be performed on this platform, including disulfide reduction, alkylation, and enzymatic digestion, followed by cocrystallization with a MALDI matrix and analysis of the sample in situ by MALDI-MS.

Transport of live yeast and zebrafish embryo on a droplet digital microfluidic platform.

We demonstrate the first programmed transport of live yeast (Saccharomyces cerevisiae) and a zebrafish embryo (Danio rerio) within droplets in a two-plate digital microfluidic device. The yeast remained viable after transport, and the actuated droplets left no yeast behind. A zebrafish embryo transported 2 hours after fertilization developed normally and hatched.

Electromechanical model for actuating liquids in a two-plate droplet microfluidic device.

Both conducting and insulating liquids can be actuated in two-plate droplet ("digital") microfluidic devices. Droplet movement is accomplished by applying a voltage across electrodes patterned beneath the dielectric-coated top and bottom plates. This report presents a general electromechanical model for calculating the forces on insulating and conducting liquids in two-plate devices.

An integrated digital microfluidic chip for multiplexed proteomic sample preparation and analysis by MALDI-MS.

To realize multiplexed sample preparation on a digital microfluidic chip for high-throughput Matrix Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS), several fluidic functions need to be integrated. These include the generation of multiple droplets from a reservoir and parallel in-line sample purification. In this paper, we develop two critical new functions in handling protein solutions and standard proteomic reagents with electrowetting-on-dielectric (EWOD) actuation, leading to an integrated chip for multiplexed sample preparation for MALDI-MS.

Droplet-based microfluidics with nonaqueous solvents and solutions.

In droplet-based ("digital") microfluidics, liquid droplets in contact with dielectric surfaces are created, moved, merged and mixed by applying AC or DC potentials across electrodes patterned beneath the dielectric. We show for the first time that it is possible to manipulate droplets of organic solvents, ionic liquids, and aqueous surfactant solutions in air by these mechanisms using only modest voltages (<100 V) and frequencies (<10 kHz). The feasibility of moving any liquid can be predicted empirically from its frequency-dependent complex permittivity, epsilon*.

Digital microfluidics with in-line sample purification for proteomics analyses with MALDI-MS.

An in-line sample purification method for MALDI-MS, which relies on the electrowetting-on-dielectric (EWOD)-based technique for digital microfluidics, is reported. In this method, a droplet containing peptides and impurities is moved by EWOD and deposited onto a Teflon-AF surface. A droplet of water is subsequently moved over the spot, where it dissolves and removes the impurities.

Electrowetting-based microfluidics for analysis of peptides and proteins by matrix-assisted laser desorption/ionization mass spectrometry.

A new technique for preparing samples for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is reported. The technique relies on electrowetting-on-dielectric (EWOD) to move droplets containing proteins or peptides and matrix to specific locations on an array of electrodes for analysis. Standard MALDI-MS reagents, analytes, concentrations, and recipes are demonstrated to be compatible with the technique.

G-factor analysis of protein secondary structure in solutions and thin films.

The biological activity of proteins is structure dependent. In this discussion, we describe development of g-factor analysis for characterizing the secondary structure of proteins in solutions and films. In g-factor analysis, experimental circular dichroism (CD) and UV absorbance spectra are converted to dimensionless g-factor spectra by dividing the differential absorbance of circularly polarized light (AL - AR) by the UV absorbance (A) at each wavelength.

Preventing Biomolecular Adsorption in Electrowetting-Based Biofluidic Chips.

Electrowetting-on-dielectric (EWOD) is a new method for moving liquids in biofluidic chips through electrical modification of the surface hydrophobicity. EWOD-based devices are reconfigurable, have low power requirements, and can handle neutral and charged analytes, as well as particulates. We show that biomolecular adsorption in EWOD is minimized by limiting the time during which no potential is applied and through choice of solution pH and electrode polarity.

Precursor tissue analogs as a tissue-engineering strategy.

Natural tissues are composed of functionally diverse cell types that are organized in spatially complex arrangements. Organogenesis of complex tissues requires a coordinated sequential transformation process, with individual stages involving time-dependent expression of cell-cell, cell-matrix, and cell-signal interactions in three dimensions. The common theme of temporal-spatial patterning of these cellular interactions is also observed in other physiological processes, such as growth and development, wound healing, and tumor migration.

A rotaxane-like complex with controlled-release characteristics.

A rotaxane-like complex, based on a dumbbell-shaped component containing an NH(2)(+) recognition site for a [25]crown-8 ring component and a slippage stopper in the form of a p-(tert-butyl)phenyl group, has been synthesized by a "threading-followed-by-stoppering" approach. The half-life for dissociation of this complex, which is very sensitive to its environment, can be varied from minutes to months by changing the temperature and the polarity of the solvent.

Surface-enhanced Raman spectroscopy of DOPA-containing peptides related to adhesive protein of marine mussel, Mytilus edulis.

The common blue marine mussel adheres to underwater surfaces using an adhesive protein (Mefp-1) extruded from its foot. This highly hydroxylated protein contains a number of unusual amino acids, including 3,4-dihydroxyphenylalanine (DOPA), which is thought to contribute to the crosslinking of the extruded threads and adhesion to the substratum. Mefp-1 adheres to a wide variety of surfaces and is ultimately biodegradable.

Surface interactions of a homologous series of alpha,omega-amino acids on colloidal silver and gold.

Surface enhanced Raman spectroscopy (SERS) was used to characterize a homologous series of alpha,omega-amino acids on colloidal gold and silver. Raman and SER spectra of the alpha,omega-amino acids, NH2(CH2)nCOOH (n = 3-7), are presented and analyzed, revealing the probable conformations of the molecules on the metal surfaces. The alpha,omega-amino acids interact with silver and gold through both the amine and carboxylate end groups, and modify the conformation of the molecular backbone in order to maximize these interactions.