Two-Step Solid-State Synthesis of Ternary Nitride Materials.

Ternary nitride materials hold promise for many optical, electronic, and refractory applications; yet, their preparation via solid-state synthesis remains challenging. Often, high pressures or reactive gases are used to manipulate the effective chemical potential of nitrogen, yet these strategies require specialized equipment. Here, we report on a simple two-step synthesis using ion-exchange reactions that yield rocksalt-derived MgZrN and MgNbN, as well as layered MgMoN.

Selectivity in Yttrium Manganese Oxide Synthesis via Local Chemical Potentials in Hyperdimensional Phase Space.

In sharp contrast to molecular synthesis, materials synthesis is generally presumed to lack selectivity. The few known methods of designing selectivity in solid-state reactions have limited scope, such as topotactic reactions or strain stabilization. This contribution describes a general approach for searching large chemical spaces to identify selective reactions.

Magnetic characterization of paramagnetic reagents by particle tracking velocimetry.

Magnetic particle characterization determines the quality of magnetic particles and is of great importance in particle technology, drug delivery, cell separation, in vivo diagnostics, and other biomedical applications. The quality of the sample depends on the particle size, intrinsic magnetic properties of the particles, and the uniformity of these properties. A commercial particle tracking velocimeter was used to record and capture dark field images of particle trajectories in an applied isodynamic magnetic field.

Defect-Accommodating Intermediates Yield Selective Low-Temperature Synthesis of YMnO Polymorphs.

In the synthesis of complex oxides, solid-state metathesis provides low-temperature reactions where product selectivity can be achieved through simple changes in precursor composition. The influence of precursor structure, however, is less understood in solid-state synthesis. Here we present the ternary metathesis reaction (LiMnO + YOCl → YMnO + LiCl) to target two yttrium manganese oxide products, hexagonal and orthorhombic YMnO, when starting from three different LiMnO precursors.

A thermal-gradient approach to variable-temperature measurements resolved in space.

Temperature is a ubiquitous environmental variable used to explore materials structure, properties and reactivity. This article reports a new paradigm for variable-temperature measurements that varies the temperature continuously across a sample such that temperature is measured as a function of sample position and not time. The gradient approach offers advantages over conventional variable-temperature studies, in which temperature is scanned during a series measurement, in that it improves the efficiency with which a series of temperatures can be probed and it allows the sample evolution at multiple temperatures to be measured in parallel to resolve kinetic and thermodynamic effects.

Catalytic behavior of hexaphenyldisiloxane in the synthesis of pyrite FeS.

Functional small molecules afford opportunities to direct solid-state inorganic reactions at low temperatures. Here, we use catalytic amounts of organosilicon molecules to influence the metathesis reaction: FeCl2 + Na2S2 → 2NaCl + FeS2. Specifically, hexaphenyldisiloxane ((C6H5)6Si2O) is shown to increase pyrite yields in metathesis reactions performed at 150 °C.

Yttrium Manganese Oxide Phase Stability and Selectivity Using Lithium Carbonate Assisted Metathesis Reactions.

In solid-state chemistry, stable phases are often missed if their synthesis is impractical, such as when decomposition or a polymorphic transition occurs at relatively low temperature. In the preparation of complex oxides, reaction temperatures commonly exceed 1000 °C with little to no control of the reaction pathway. Thus, a prerequisite for exploring the synthesis of complex oxides is to identify reactions with intermediates that are kinetically competent at low temperatures, as provided by assisted metathesis reactions.

Selective Formation of Yttrium Manganese Oxides through Kinetically Competent Assisted Metathesis Reactions.

The synthesis of complex oxides requires high temperatures to overcome barriers imparted by solid-state diffusion; as such, reactions typically yield the most stable polymorph for a given composition. To synthesize new or metastable complex oxides, kinetically competent reactions with lower initial energy barriers must be devised to control the reaction pathway and resulting products. This contribution details the selective synthesis of different yttrium manganese oxides through assisted metathesis reactions between MnO, YCl, and ACO under flowing oxygen; where A = Li, Na, K.

Continuous Quadrupole Magnetic Separation of Islets during Digestion Improves Purified Porcine Islet Viability.

Islet transplantation (ITx) is an emerging and promising therapy for patients with uncontrolled type 1 diabetes. The islet isolation and purification processes require exposure to extended cold ischemia, warm-enzymatic digestion, mechanical agitation, and use of damaging chemicals for density gradient separation (DG), all of which reduce viable islet yield. In this paper, we describe initial proof-of-concept studies exploring quadrupole magnetic separation (QMS) of islets as an alternative to DG to reduce exposure to these harsh conditions.

Interaction of ARF-1.1 and neuronal calcium sensor-1 in the control of the temperature-dependency of locomotion in Caenorhabditis elegans.

Neuronal calcium sensor-1 (NCS-1) mediates changes in cellular function by regulating various target proteins. Many potential targets have been identified but the physiological significance of only a few has been established. Upon temperature elevation, Caenorhabditis elegans exhibits reversible paralysis.

Magnetic particle characterization-magnetophoretic mobility and particle size.

Quantitative characterization of magnetic particles is useful for analysis and separation of labeled cells and magnetic particles. A particle velocimeter is used to directly measure the magnetophoretic mobility, size, and other parameters of magnetic particle suspensions. The instrument provides quantitative video analysis of particles and their motion.

The Geriatrics in Primary Care Demonstration: Integrating Comprehensive Geriatric Care into the Medical Home: Preliminary Data.

Three thousand nine hundred thirty-one veterans aged 75 and older receive primary care (PC) in two large practices of the Department of Veterans Affairs (VA) Boston Healthcare System. Cognitive and functional disabilities are endemic in this group, creating needs that predictably exceed available or appropriate resources. To address this problem, Geriatrics in Primary Care (GPC) embeds geriatric services directly into primary care.

Demonstration of binding of neuronal calcium sensor-1 to the cav2.1 p/q-type calcium channel.

In neurons, entry of extracellular calcium (Ca(2+)) into synaptic terminals through Cav2.1 (P/Q-type) Ca(2+) channels is the driving force for exocytosis of neurotransmitter-containing synaptic vesicles. This class of Ca(2+) channel is, therefore, pivotal during normal neurotransmission in higher organisms.

Computational Fluid Dynamics Simulation of a Quadrupole Magnetic Sorter Flow Channel: Effect of Splitter Position on Nonspecific Crossover.

In the Quadrupole Magnetic Sorter (QMS) magnetic particles enter a vertical flow annulus and are separated from non-magnetic particles by radial deflection into an outer annulus where the purified magnetic particles are collected via a flow splitter. The purity of magnetically isolated particles in QMS is affected by the migration of nonmagnetic particles across transport lamina in the annular flow channel. Computational Fluid Dynamics (CFD) simulations were used to predict the flow patterns, pressure drop and nonspecific crossover in QMS flow channel for the isolation of pancreatic islets of Langerhans.

Paramagnetic microparticles do not elicit islet cytotoxicity with co-culture or host immune reactivity after implantation.

Background: Paramagnetic microparticles (MPs) may be useful in pancreatic islet purification, in particular purification of porcine islets as a potential xenotransplantation product. We assessed whether MPs affect islet function or induce an adverse effect following implantation.

Methods: Porcine islets were co-cultured with 0, 500, and 1500 MPs per islet equivalent (IE) for 1 day and with 0 and 1500 MPs/IE for 7 days.

Application of magnetic particle tracking velocimetry to quadrupole magnetic sorting of porcine pancreatic islets.

Magnetic isolation is a promising method for separating and concentrating pancreatic islets of Langerhans for transplantation in Type 1 diabetes patients. We are developing a continuous magnetic islet sorter to overcome the restrictions of current purification methods that result in limited yield and viability. In Quadrupole Magnetic Sorting (QMS) islets are magnetized by infusing superparamagnetic microbeads into islets' vasculature via arteries that serve the pancreas.

Experiments with osteoblasts cultured under varying orientations with respect to the gravity vector.

Substrate attachment is crucial for normal growth and differentiation of many cell types. To better understand the role of gravity in osteoblast attachment and growth in vitro, 17-day-old embryonic chick calvarial osteoblasts were subjected to directional variations with respect to gravity. Osteoblasts, grown in MEM or DME supplemented with 10% FBS and attached to type I collagen-coated coverslips, were loaded into cylindrical containers completely filled with medium and oriented so that cells were either atop or beneath, or coverslips continuously rotated ( approximately 2 rpm) in a clinostat, thereby continuously changing their orientation with respect to gravity.

Concentration control for protein crystallization via a continuously-fed crystallization chamber.

A continuously-fed crystallization chamber that allows for kinetic path control through the crystallization phase diagram (from labile/nucleation to metastable/growth) was fabricated and used to crystallize lysozyme. A lumped kinetic model was developed, and parameters for heterogeneous nucleation kinetics were determined. Heterogeneous nucleation was found to have faster nucleation kinetics and slower growth kinetics than homogeneous nucleation, as expected.

A controlled trial of a Quit and Win contest.

Purpose: To evaluate the impact of a state-of-the-art Quit and Win contest on tobacco quit rates at 3, 6, and 12 months after the 30-day quit period.

Design: Quasi-experimental with a volunteer sample of 494 Quit and Win contest registrants (treatment group) and 512 randomly selected tobacco users not exposed to the promotional media campaign (control group). Intervention included a 30-day quit period to be eligible for large cash prizes; provider advice via weekly mailings; online and telephone quit assistance; media campaign; and community support.

Overview of SHOT hardware capabilities and range of cell biology experiment designs.

Cell science hardware is currently available for lease or production by SHOT(R). The SHOT Avian Development Facility (ADF) is a single middeck locker experiment containing two carousels capable of rotating at variable g. Each carousel accommodates 18 40-ml vessels that can be adapted for the cultivation of avian or reptilian eggs, small invertebrates, zebra fish, small plants, seeds, spores, cells or tissues.

Overview of the spaceflight radiation environment and its impact on cell biology experiments.

Variables studied in typical cellular radiation biology experiments are cell killing, mutagenesis, transformation to malignancy, heritable damage, and DNA damage and repair. Dose response curves for cells exposed to low-LET radiations and some high LET radiations are well known. The low-LET dose rate in low earth orbit is roughly 1.

Diet as a factor in behavioral radiation protection following exposure to heavy particles.

Major risks associated with radiation exposures on deep space missions include carcinogenesis due to heavy-particle exposure of cancer-prone tissues and performance decrements due to neurological damage produced by heavy particles. Because exposure to heavy particles can cause oxidative stress, it is possible that antioxidants can be used to mitigate these risks (and possibly some health risks of microgravity). To assess the capacity of antioxidant diets to mitigate the effects of exposure to heavy particles, rats were maintained on antioxidant diets containing 2% blueberry or strawberry extract or a control diet for 8 weeks prior to exposure to 1.

Experiments with osteoblasts cultured under hypergravity conditions.

To understand further the role of gravity in osteoblast attachment, osteoblasts were subjected to hypergravity conditions in vitro. Scanning electron microscopy of all confluent coverslips from FPA units show that the number of attached osteoblasts was similar among gravitational levels and growth durations (~90 cells/microscopic field). Specifically, confluent 1.

Effectiveness of a quit and win contest with a low-income population.

Background: In a two-group quasi-experimental study, we evaluated the impact of a quit and win contest on quitting among low-income tobacco users and identified contest elements used by successful quitters. Low-income tobacco users have been largely untouched by tobacco cessation approaches.

Methods: A volunteer sample of 248 low-income tobacco users were recruited from quit and win contest registrants (treatment group).