Traumatic Brain Injury in a Well: A Modular Three-Dimensional Printed Tool for Inducing Traumatic Brain Injury In vitro.

Traumatic brain injury (TBI) is a major health problem that affects millions of persons worldwide every year among all age groups, mainly young children, and elderly persons. It is the leading cause of death for children under the age of 16 and is highly correlated with a variety of neuronal disorders, such as epilepsy, and neurodegenerative disease, such as Alzheimer's disease or amyotrophic lateral sclerosis. Over the past few decades, our comprehension of the molecular pathway of TBI has improved, yet despite being a major public health issue, there is currently no U.S. Food and Drug Administration-approved treatment for TBI, and a gap remains between these advances and their application to the clinical treatment of TBI. One of the major hurdles for pushing TBI research forward is the accessibility of TBI models and tools. Most of the TBI models require costume-made, complex, and expensive equipment, which often requires special knowledge to operate. In this study, we present a modular, three-dimensional printed TBI induction device, which induces, by the pulse of a pressure shock, a TBI-like injury on any standard cell-culture tool. Moreover, we demonstrate that our device can be used on multiple systems and cell types and can induce repetitive TBIs, which is very common in clinical TBI. Further, we demonstrate that our platform can recapitulate the hallmarks of TBI, which include cell death, decrease in neuronal functionality, axonal swelling (for neurons), and increase permeability (for endothelium). In addition, in view of the continued discussion on the need, benefits, and ethics of the use of animals in scientific research, this in vitro, high-throughput platform will make TBI research more accessible to other labs that prefer to avoid the use of animals yet are interested in this field. We believe that this will enable us to push the field forward and facilitate/accelerate the availability of novel treatments.

Improved design for a highly efficient pulsed-valve supersonic source with extended operating frequency range.

We present a new design for a pulsed supersonic-beam source, inspired by the Even-Lavie valve, which is about four times more energy efficient than its predecessor and can run at more than double the repetition rate without experiencing resonances. Its characteristics make it a better candidate as a source for cryogenic-related experiments as well as spectroscopy with rapidly pulsed lasers. The new design is also simpler to build and is more robust, making it accessible to a larger portion of the scientific community.

Understanding the quantum nature of low-energy C(3P j ) + He inelastic collisions.

Inelastic collisions that occur between open-shell atoms and other atoms or molecules, and that promote a spin-orbit transition, involve multiple interaction potentials. They are non-adiabatic by nature and cannot be described within the Born-Oppenheimer approximation; in particular, their theoretical modelling becomes very challenging when the collision energies have values comparable to the spin-orbit splitting. Here we study inelastic collisions between carbon in its ground state C(3Pj=0) and helium atoms-at collision energies in the vicinity of spin-orbit excitation thresholds (~0.2 and 0.5 kJ mol-1)-that result in spin-orbit excitation to C(3Pj=1) and C(3Pj=2). State-to-state integral cross-sections are obtained from crossed-beam experiments with a beam source that provides an almost pure beam of C(3Pj=0) . We observe very good agreement between experimental and theoretical results (acquired using newly calculated potential energy curves), which validates our characterization of the quantum dynamical resonances that are observed. Rate coefficients at very low temperatures suitable for chemical modelling of the interstellar medium are also calculated.

Supersonic beams at high particle densities: model description beyond the ideal gas approximation.

Supersonic molecular beams constitute a very powerful technique in modern chemical physics. They offer several unique features such as a directed, collision-free flow of particles, very high luminosity, and an unsurpassed strong adiabatic cooling during the jet expansion. While it is generally recognized that their maximum flow velocity depends on the molecular weight and the temperature of the working fluid in the stagnation reservoir, not a lot is known on the effects of elevated particle densities. Frequently, the characteristics of supersonic beams are treated in diverse approximations of an ideal gas expansion. In these simplified model descriptions, the real gas character of fluid systems is ignored, although particle associations are responsible for fundamental processes such as the formation of clusters, both in the reservoir at increased densities and during the jet expansion. In this contribution, the various assumptions of ideal gas treatments of supersonic beams and their shortcomings are reviewed. It is shown in detail that a straightforward thermodynamic approach considering the initial and final enthalpy is capable of characterizing the terminal mean beam velocity, even at the liquid-vapor phase boundary and the critical point. Fluid properties are obtained using the most accurate equations of state available at present. This procedure provides the opportunity to naturally include the dramatic effects of nonideal gas behavior for a large variety of fluid systems. Besides the prediction of the terminal flow velocity, thermodynamic models of isentropic jet expansions permit an estimate of the upper limit of the beam temperature and the amount of condensation in the beam. These descriptions can even be extended to include spinodal decomposition processes, thus providing a generally applicable tool for investigating the two-phase region of high supersaturations not easily accessible otherwise.

Rapidly pulsed helium droplet source.

A pulsed valve connected to a closed-cycle cryostat was optimized for producing helium droplets. The pulsed droplet beam appeared with a bimodal size distribution. The leading part of the pulse consists of droplets suitable for doping with molecules. The average size of this part can be varied between 10(4) and 10(6) helium atoms, and the width of the distribution is smaller as compared to a continuous-flow droplet source. The system has been tested in a single pulse mode and at repetition rates of up to 500 Hz with almost constant intensity. The droplet density was found to be increased by more than an order of magnitude as compared to a continuous-flow droplet source.

Stopping supersonic beams with a series of pulsed electromagnetic coils: an atomic coilgun.

We report the stopping of an atomic beam, using a series of pulsed electromagnetic coils. We use a supersonic beam of metastable neon created in a gas discharge as a monochromatic source of paramagnetic atoms. A series of coils is fired in a timed sequence to bring the atoms to near rest, where they are detected on a microchannel plate. Applications to fundamental problems in physics and chemistry are discussed.

Efficient cooling in supersonic jet expansions of supercritical fluids: CO and CO2.

Pulsed, supersonic beams of pure carbon monoxide and carbon dioxide at stagnation conditions above their critical point have been investigated by time-of-flight measurements as a function of pressure and temperature. Although both molecules form clusters readily in adiabatic expansions, surprisingly large speed ratios (above 100) indicative of very low translational temperatures (below 0.1 K) have been achieved. In particular, the supersonic expansion of CO(2) at stagnation temperatures slightly above the phase transition to the supercritical state results in unprecedented cold beams. This efficient cooling is attributed to the large values of the heat capacity ratio of supercritical fluids in close vicinity of their critical point.