Forming free and thermally stable bipolar resistive switching behavior was observed in the memory devices composed of graphene oxide (GO) thin films on ITO coated glass substrate with Platinum (Pt) as the top electrode. The switching between the low resistance state and high resistance state showed a reliable and repeating behavior with an on/off ratio of 104 at room temperature. The Pt/GO/ITO device showed metallic and semiconducting characteristics in low and high resistance states, respectively, when resistance was measured as a function of temperature. Ohmic conduction was found to dominate in all regions of switching operation except for the high voltage regime of high resistance state where space charge limited conduction was found to be the main mechanism of current conduction. The device showed good endurance up to 104 s and retention characteristics up to 100 cycles with on/off ratio ∼104. The switching mechanism was found to be governed by migration of oxygen between GO layer and bottom ITO electrode, which was further confirmed by Raman Spectroscopy. The device exhibited stable bipolar switching characteristics with good retention and endurance properties at high temperatures up to 500 K. The graphene oxide based memory devices fabricated by simple chemical method have potential in the field of nonvolatile memory applications well above the room temperature.

Metabolic syndrome is characterized by a cluster of metabolic disorders, such as reduced glucose tolerance, hyperinsulinemia, hypertension, visceral obesity and lipid disorders. The benefit of exercise in maintaining total metabolic control is well known and recent research indicates that AMP-activated protein kinase (AMPK) may play an important role in exercise-related effects. AMPK is considered as a master switch in regulating glucose and lipid metabolism. AMPK is an enzyme that works as a fuel gauge, being activated in conditions of high phosphate depletion. In the liver, activation of AMPK results in decreased production of plasma glucose, cholesterol, triglyceride and enhanced fatty acid oxidation. AMPK is also robustly activated by skeletal muscle contraction and myocardial ischemia, and is involved in the stimulation of glucose transport and fatty acid oxidation by these stimuli. In adipose tissue, activated AMPK inhibits deposition of fat, but enhances breakdown and burning of stored fat, resulting in reduction of body weight. The two leading diabetic drugs, namely metformin and rosiglitazone, and adipokines, such as adiponectin and leptin, show their metabolic effects partially through AMPK. These data suggest that AMPK may be a key player in the development of new treatments for obesity, Type 2 diabetes and the metabolic syndrome. In this review, the author provide insight into the role of AMPK as a probable target for treatment of metabolic syndrome.

The growing demand for portable and bendable nonvolatile memory systems has motivated extensive research in the field of flexible resistive random access memory (RRAM) devices. This study investigated the resistive switching and flexibility behavior of zinc oxide nanorods (ZNs) incorporated graphene oxide (GO) sheets. GOZNs-based RRAM devices having top metal aluminum electrodes were fabricated on flexible indium tin oxide (ITO) coated polyethylene terephthalate (ITOPET) substrate. The devices having the structure Al/GOZNs/ITOPET showed typical bipolar resistive switching characteristics with switching voltages lower than those of Al/GO/ITOPET devices. The significant (∼50%) decrement in operating voltages in the case of GOZNs-based RRAM was attributed to enhanced concentration of oxygen vacancies into the GO matrix due to the incorporation of ZNs, which was supported by X-ray photoelectron spectroscopy studies. These memory devices showed repeatable and reliable switching characteristics having an on/off ratio of ∼100, lower switching voltages, good retention properties up to ∼10 4 s, and endurance performance over 200 cycles. The resistance ratio of the GOZNs RRAM devices was maintained almost constant even for the extreme bending radius of 4 mm and mechanical flexing test over 10 3 cycles, indicating excellent flexibility. These GOZNs-based RRAM devices showed great potential for use in future flexible nonvolatile memory devices.

Multilevel resistive switching was observed in random access memory device using amorphous SmGdO3 (SGO) ternary oxide thin films. Non-volatile and stable 4-level resistance states with sufficient margin of resistance ratios were observed by varying compliance current which was attributed to compliance current dependent variation in size of conducting filaments. As fabricated Pt/SGO/Pt devices exhibited excellent switching parameters such as stable resistance ratios of reset (ON) to set (OFF) states, non-overlapping switching voltages, excellent data retention, and endurance. Temperature dependent variation of resistances of ON and OFF states of the device was studied to elucidate current conduction and resistive switching mechanisms.