No abstract

Electrochemical properties of most supercapacitor devices degrade quickly when the operating temperature deviates from room temperature. To exploit the potential of rGO in supercapacitors at extreme temperatures, a resilient electrolyte that is functional over a wide temperature range is also required. In this study, we have implemented a flexible, low-resistant solid-state electrolyte membrane (SSEM) into symmetric rGO electrodes to realize supercapacitor devices that operate in the temperature range −70 to 220 °C. The SSEM consists of a polycation− polybenzimidazole blend that is doped with phosphoric acid (H 3 PO 4 ), and this material displays uniquely high conductivity values that range from 50 to 278 mS cm −1 in the temperature range −25 to 220 °C. The fabricated supercapacitor produced a maximum capacitance of 6.8 mF cm −2 at 100 °C. Energy and power densities ranged from 0.83 to 2.79 mW h cm −2 and 90 to 125 mW cm −2 , respectively. The energy storage mechanism with a SSEM occurs by excess H 3 PO 4 migrating from the membrane host into the electrochemical double layer in rGO electrodes. The high-temperature operation is enabled by the polycation in the SSEM anchoring phosphate type of anions preventing H 3 PO 4 evaporation. Low-temperature operation of the supercapacitor with the SSEM is attributed to the PC−PBI matrix depressing the freezing point of H 3 PO 4 to maintain structural proton diffusion.

No abstract

Noninvasive and label-free vibrational spectroscopy and microscopy methods have shown great potential for clinical diagnosis applications. Raman spectroscopy is based on inelastic light scattering due to rotational and vibrational modes of molecular bonds. It has been shown that Raman spectra provide chemical signatures of changes in biological tissues in different diseases, and this technique can be employed in label-free monitoring and clinical diagnosis of several diseases, including cardiovascular studies. However, there are very few literature reviews available to summarize the state of art and future applications of Raman spectroscopy in cardiovascular diseases, particularly cardiac hypertrophy. In addition to conventional clinical approaches such as electrocardiography (ECG), echocardiogram (cardiac ultrasound), positron emission tomography (PET), cardiac computed tomography (CT), and single photon emission computed tomography (SPECT), applications of vibrational spectroscopy and microscopy will provide invaluable information useful for the prevention, diagnosis, and treatment of cardiovascular diseases. Various in vivo and ex vivo investigations can potentially be performed using Raman imaging to study and distinguish pathological and physiological cardiac hypertrophies and understand the mechanisms of other cardiac diseases. Here, we have reviewed the recent literature on Raman spectroscopy to study cardiovascular diseases covering investigations on the molecular, cellular, tissue, and organ level.

Conventional methods of studying posttraumatic stress disorder (PTSD) have proven to be insufficient for diagnosis. We have reviewed clinical and preclinical imaging techniques as well as molecular, cellular, and behavioral indicators for PTSD.