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Pressure sensors are a key component in electronic skin (e-skin) sensing systems. Most reported resistive pressure sensors have a high sensitivity at low pressures (<5 kPa) to enable ultra-sensitive detection. However, the sensitivity drops significantly at high pressures (>5 kPa), which is inadequate for practical applications. For example, actions like a gentle touch and object manipulation have pressures below 10 kPa, and 10–100 kPa, respectively. Maintaining a high sensitivity in a wide pressure range is in great demand. Here, a flexible, wide range and ultra-sensitive resistive pressure sensor with a foam-like structure based on laser-scribed graphene (LSG) is demonstrated. Benefitting from the large spacing between graphene layers and the unique v-shaped microstructure of the LSG, the sensitivity of the pressure sensor is as high as 0.96 kPa−1 in a wide pressure range (0 ~ 50 kPa). Considering both sensitivity and pressure sensing range, the pressure sensor developed in this work is the best among all reported pressure sensors to date. A model of the LSG pressure sensor is also established, which agrees well with the experimental results. This work indicates that laser scribed flexible graphene pressure sensors could be widely used for artificial e-skin, medical-sensing, bio-sensing and many other areas.

A resistive random access memory (RRAM) device with a tunable switching window is demonstrated for the first time. The SET voltage can be continuously tuned from 0.27 to 4.5 V by electrical gating from -10 to +35 V. The gate-controlled bilayer graphene-electrode RRAM can function as 1D1R and potentially increase the RRAM density.

Vibrational circular dichroism (VCD) spectroscopy is utilized to reveal the detailed conformational distributions of the dominant serine species in aqueous solutions under three representative pH conditions of 1.0, 5.7, and 13.0, together with vibrational absorption (VA) spectroscopy, density functional theory (DFT), and molecular dynamics simulation. The experimental VA and VCD spectra of serine in H(2)O and D(2)O in the fingerprint region under three pH values are obtained. DFT calculations at the B3LYP/6-311++G(d,p) level are carried out for the protonated, zwitterionic, and deprotonated serine species. The lowest-energy conformers of all three species are identified and their corresponding VA and VCD spectra simulated. A comparison between the gas-phase simulations and the experimental VA and VCD spectra suggests that one or two of the most stable conformers of each species contribute predominantly to the observed data, although some discrepancies are noted. To account for the solvent effects, both the polarizable continuum model and the explicit solvation model are considered. Hydrogen-bonded protonated, zwitterionic, and deprotonated serine-(water)(6) clusters are constructed based on radial distribution function analyses and molecular dynamics snapshots. Geometry optimization and VA and VCD simulations are performed for these clusters at the B3LYP/6-311++G(d,p) level. Inclusion of the explicit water molecules is found to improve the agreement between theory and experiment noticeably in all three cases, thus enabling conclusive conformational distribution analyses of serine in aqueous solutions directly.

A new cyclic peroxide plakortisinic acid (1), and a new ketone derivative (2), in addition to six known compounds, an α,β-unsaturated ester (3), plakortide N (4), plakortide F (5) and its free acid (6), plakortone D (7), and a furan-containing molecule (8), were isolated from a species of Plakortis from Jamaica. The structures were elucidated by interpretation of 1D and 2D NMR spectra, and mass spectrometry data and by comparison with data from the literature. Comparison between experimental and calculated optical rotations allowed the assignment of absolute configuration of 1 and 2. The isolated compounds have been evaluated for their antimicrobial, antimalarial, anticancer, anti-Mtb, and anti HIV-1 activity.

Device-to-Device (D2D) communication is offering smart phone users a choice to share files with each other without communicating with the cellular network. In this paper, we discuss the behaviors of two characters in the D2D data transaction model from an economic point of view: the data buyers who wish to buy a certain quantity of data, as well as the data sellers who wish to sell data through the D2D network. The optimal price and purchasing strategies are analyzed and deduced based on game theory.

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