Intracranial hemorrhage detected through a craniotomy site with point of care ultrasound.

A 60-year-old male presented to the emergency department with acute change in mental status while recovering from a recent hemicraniectomy. During evaluation by the emergency physician, a point-of-care ultrasound (POCUS) was performed using the patient's existing craniectomy site as a sonographic window. Multiple areas of intracranial hemorrhage were visualized on POCUS and head computed tomography scan ultimately requiring urgent neurosurgical intervention. Our case report demonstrates an innovative application of POCUS in the emergency department- setting that has potential to expedite diagnosis and management of life-threatening neurosurgical etiologies, such as hemorrhage and midline shift, in a unique patient population.

Evaluation of a Novel Wireless Transmission System for Trauma Ultrasound Examinations From Moving Ambulances.

Objective: To determine if physicians trained in ultrasound interpretation perceive a difference in image quality and usefulness between Extended Focused Assessment with Sonography ultrasound examinations performed at bedside in a hospital vs. by emergency medical technicians minimally trained in medical ultrasound on a moving ambulance and transmitted to the hospital via a novel wireless system. In particular, we sought to demonstrate that useful images could be obtained from patients in less than optimal imaging conditions; that is, while they were in transport. Methods: Emergency medical technicians performed the examinations during transport of blunt trauma patients. Upon patient arrival at the hospital, a bedside Extended Focused Assessment with Sonography examination was performed by a physician. Both examinations were recorded and later reviewed by physicians trained in ultrasound interpretation. Results: Data were collected on 20 blunt trauma patients over a period of 13 mo. Twenty ultrasound-trained physicians blindly compared transmitted vs. bedside images using 11 Questionnaire for User Interaction Satisfaction scales. Four paired samples t-tests were conducted to assess mean differences between ratings for ambulatory and base images. Conclusion: Although there is a slight tendency for the average rating across all subjects and raters to be slightly higher in the base than in the ambulatory condition, none of these differences are statistically significant. These results suggest that the quality of the ambulatory images was viewed as essentially as good as the quality of the base images.

Dynamic and programmable self-assembly of micro-rafts at the air-water interface.

Dynamic self-assembled material systems constantly consume energy to maintain their spatiotemporal structures and functions. Programmable self-assembly translates information from individual parts to the collective whole. Combining dynamic and programmable self-assembly in a single platform opens up the possibilities to investigate both types of self-assembly simultaneously and to explore their synergy. This task is challenging because of the difficulty in finding suitable interactions that are both dissipative and programmable. We present a dynamic and programmable self-assembling material system consisting of spinning at the air-water interface circular magnetic micro-rafts of radius 50 µm and with cosinusoidal edge-height profiles. The cosinusoidal edge-height profiles not only create a net dissipative capillary repulsion that is sustained by continuous torque input but also enable directional assembly of micro-rafts. We uncover the layered arrangement of micro-rafts in the patterns formed by dynamic self-assembly and offer mechanistic insights through a physical model and geometric analysis. Furthermore, we demonstrate programmable self-assembly and show that a 4-fold rotational symmetry encoded in individual micro-rafts translates into 90° bending angles and square-based tiling in the assembled structures of micro-rafts. We anticipate that our dynamic and programmable material system will serve as a model system for studying nonequilibrium dynamics and statistical mechanics in the future.

Anisotropic Liquid Microcapsules from Biomimetic Self-Folding Polymer Films.

We demonstrated a novel approach for the fabrication of anisotropic capsules with liquid content using biomimetic self-folding thermoresponsive polymer films. The behavior of self-folding films is very similar to actuation in plants, where nonhomogenous swelling results in complex movements such as twisting, bending, or folding. This approach allows the design of anisotropic liquid capsules with rodlike and dumbbell-like morphologies. We found that these capsules are able to assemble into different complex structures, such as nematic-like one and 3D network depending on their morphology.

Reversible thermosensitive biodegradable polymeric actuators based on confined crystallization.

We discovered a new and unexpected effect of reversible actuation of ultrathin semicrystalline polymer films. The principle was demonstrated on the example of thin polycaprolactone-gelatin bilayer films. These films are unfolded at room temperature, fold at temperature above polycaprolactone melting point, and unfold again at room temperature. The actuation is based on reversible switching of the structure of the hydrophobic polymer (polycaprolactone) upon melting and crystallization. We hypothesize that the origin of this unexpected behavior is the orientation of polycaprolactone chains parallel to the surface of the film, which is retained even after melting and crystallization of the polymer or the "crystallization memory effect". In this way, the crystallization generates a directed force, which causes bending of the film. We used this effect for the design of new generation of fully biodegradable thermoresponsive polymeric actuators, which are highly desirable for bionano-technological applications such as reversible encapsulation of cells and design of swimmers.

Stimuli-responsive hierarchically self-assembled 3D porous polymer-based structures with aligned pores.

We have developed a novel approach for the fabrication of self-assembled porous materials with uniaxial tubular pores. The approach is based on the use of microtubes formed by stimuli-induced rolling of polymer bilayers consisting of hydrophobic and stimuli-responsive hydrophilic polymers. Different objects, for example yeast cells, can be encapsulated inside the tubes during their rolling. The self-rolled tubes filled with the yeast cells are capable of controlled self-assembly and form a uniaxial tubular homogeneously filled scaffold. Moreover, our approach allows design of porous materials with the pores having different properties.

Shape-programmed folding of stimuli-responsive polymer bilayers.

We investigated the folding of rectangular stimuli-responsive hydrogel-based polymer bilayers with different aspect ratios and relative thicknesses placed on a substrate. It was found that long-side rolling dominates at high aspect ratios (ratio of length to width) when the width is comparable to the circumference of the formed tubes, which corresponds to a small actuation strain. Rolling from all sides occurs for higher actuation, namely when the width and length considerably exceed the deformed circumference. In the case of moderate actuation, when both the width and length are comparable to the deformed circumference, diagonal rolling is observed. Short-side rolling was observed very rarely and in combination with diagonal rolling. On the basis of experimental observations, finite-element modeling and energetic considerations, we argued that bilayers placed on a substrate start to roll from corners due to quicker diffusion of water. Rolling from the long-side starts later but dominates at high aspect ratios, in agreement with energetic considerations. We have shown experimentally and by modeling that the main reasons causing a variety of rolling scenarios are (i) non-homogenous swelling due to the presence of the substrate and (ii) adhesion of the polymer to the substrate.

Fully biodegradable self-rolled polymer tubes: a candidate for tissue engineering scaffolds.

We report an approach for the fabrication of fully biodegradable self-rolled tubes based on patterned polysuccinimide/polycaprolactone bilayers. These polymers are biocompatible, biodegradable, produced industrially, and are already approved for biomedical purposes. Both polycaprolactone and polysuccinimide are hydrophobic and intrinsically water-insoluble. Polysuccinimide, however, hydrolyzes in physiological buffer environment yielding water-swellable polyaspartic acid that causes the rolling of the polymer bilayer and formation of tubes. We demonstrate the possibility to encapsulate yeast cells using self-rolled tubes.

Influence of chain charge and complexation on the overlap and entanglements formation in poly(acrylic acid) salt-containing aqueous solutions.

Dilute-semidilute regime crossover in aqueous solutions of partly neutralized poly(acrylic acid) and of its complex with tetradecyltrimethylammonium bromide was studied by light scattering and viscometry methods. The chain charge growth causes the decrease of overlap concentration (c*) and the increase of the entanglements formation concentration (ce), hence, the semidilute unentangled regime of solution expands. Complexation of the polyelectrolyte with an oppositely charged surfactant leads to c* increase and to ce decrease. It is shown that in semidilute entangled solutions the surfactant acts as an effective structuring agent because of the binding of polyelectrolyte chains via surfactant micelles.