A chiral switchable photovoltaic ferroelectric 1D perovskite.

Spin and valley degrees of freedom in materials without inversion symmetry promise previously unknown device functionalities, such as spin-valleytronics. Control of material symmetry with electric fields (ferroelectricity), while breaking additional symmetries, including mirror symmetry, could yield phenomena where chirality, spin, valley, and crystal potential are strongly coupled. Here we report the synthesis of a halide perovskite semiconductor that is simultaneously photoferroelectricity switchable and chiral. Spectroscopic and structural analysis, and first-principles calculations, determine the material to be a previously unknown low-dimensional hybrid perovskite (R)-(-)-1-cyclohexylethylammonium/(S)-(+)-1 cyclohexylethylammonium) PbI3. Optical and electrical measurements characterize its semiconducting, ferroelectric, switchable pyroelectricity and switchable photoferroelectric properties. Temperature dependent structural, dielectric and transport measurements reveal a ferroelectric-paraelectric phase transition. Circular dichroism spectroscopy confirms its chirality. The development of a material with such a combination of these properties will facilitate the exploration of phenomena such as electric field and chiral enantiomer-dependent Rashba-Dresselhaus splitting and circular photogalvanic effects.

Unexploded Ordnance Management.

The purpose of this Clinical Practice Guide is to provide details on the procedures to safely remove unexploded ordnance from combat patients, both loose and impaled, to minimize the risks to providers and the medical treatment facility while ensuring the best outcome for the patient. Military ordnance, to include bullets, grenades, flares, and explosive ordnance, retained by a patient can be a risk to all individuals and equipment along the continuum of care. This is especially true from the point of injury to the first treatment facility. Management of patients with unexploded ordnance either on or in their body is a rare event during combat surgery. Loose munitions are usually noted and easily removed prior to the patient receiving medical treatment. However, impaled munitions provide a significant challenge. These are usually caused by large caliber, high-velocity projectiles. Patients who survive to arrive at a treatment facility must be triaged safely and simultaneously treated appropriately to ensure both the survival of the patient and the treatment team. Between WWII and the Somalia conflict, there have been 36 reported cases of unexploded ordnance from U.S. soldiers. Since 2005, there have been six known cases during the U.S. wars in Afghanistan and Iraq and one additional case in Pakistan. Optimal outcomes require a basic knowledge of explosives and triggering mechanisms, as well as adherence to basic principles of trauma resuscitation and surgery.