Determination of interaction strength between corrole and phenol derivatives in aqueous media using atomic force microscopy

Atomic force microscopy (AFM) was used to measure single interaction forces between corrole (host) and phenol derivatives (guests) in aqueous media. A gold tip was modified with thiol derivatives of corrole via the Au–S covalent bond. Such a tip was used to measure adhesion forces with a planar gold substrate modified with thiol derivatives of phenol and ortho-nitrophenol in aqueous solutions. The mean force between the corrole and ortho-nitrophenol was higher than that between corrole and phenol, probably reflecting stronger hydrogen bond interaction in the former complex. In the presence of a supporting electrolyte (0.1 M K₂SO₄), the mean force increased, suggesting that electrostatic and π–π interactions play an essential role in the adhesion force. In addition, the adhesion force measured at pH 6.0 was larger than that at pH 10, reflecting the electrostatic repulsion at the higher pH. These behaviours are consistent with the potentiometric responses of a liquid membrane based on corrole to phenolic compounds. Also, the values of forces for the interaction between corrole and phenol derivatives showed the same tendency as energy calculated for these complexes. The Poisson method was used for the calculation of the single force of the chemical bond between the corrole host and the phenolic guests.     

A 0.5-V, 2-nW, 55-dB DR,fourth-order bandpass filter using single branch biquads: An efficient design for FoM enhancement

A compact nano-power fourth-order bandpass filter operating from a 0.5 V supply, with an adjustable center frequency ranging from 125 Hz to 16 kHz, is presented. The filter is constituted from cascadable second-order circuit cells that are realized by a network of three transistors and two capacitors comprising only one branch of bias current. The measurement results of the filter fabricated in a 0.18-μm CMOS IC process indicate that, for a 1 kHz center frequency, a dynamic range of 55 dB is obtained from 2 nW power consumption. These results lead to best figure of merit achieved when compared to other existing designs to date.     

Zero-Power Defense Done Right: Shielding IMDs from Battery-Depletion Attacks

The wireless capabilities of modern Implantable Medical Devices (IMDs) make them vulnerable to security attacks. One prominent attack, which has disastrous consequences for the patient’s wellbeing, is the battery Denial-of-Service attack whereby the IMD is occupied with continuous authentication requests from an adversary with the aim of depleting its battery. Zero-Power Defense (ZPD), based on energy harvesting, is known to be an excellent protection against these attacks. This paper raises essential design considerations for employing ZPD techniques in commercial IMDs, offers a critical review of ZPD techniques found in literature and, subsequently, gives crucial recommendations for developing comprehensive ZPD solutions.

     

The structure of 20 oximo-5α-pregnano-16-eno[3,4-C]-1′,2′,5′-oxadiazole (HS976)

The crystal and the molecular structure of the steroidal oxadiazole 20-oximo-5-pregnano-16-eno[3,4-C]-1,2,5-oxadiazole (C₂₁H₂₈N₂O₃) has been determined by direct methods, and refined to a finalR of 0.086 for 3100 observed reflections. The compound crystallizes in space groupP2₁, with cell dimensionsa=18.284(6),b=13.992(4),c=7.370(3)Å,=96.97(3)°;V=1885 ų,Z=4,D _x =1.27 g cm^–3, =1.5418 Å, (CuK =5.95 cm^–1. The two independent molecules are related by a pseudo twofold axis. Both molecules exhibit similar overall topography, rings A, B, C, and D adopting distorted sofa, chair, chair, and distorted envelope conformations, respectively.     

A Low Temperature Analysis of the Boundary Driven Kawasaki Process

Low temperature analysis of nonequilibrium systems requires finding the states with the longest lifetime and that are most accessible from other states. We determine these dominant states for a one-dimensional diffusive lattice gas subject to exclusion and with nearest neighbor interaction. They do not correspond to lowest energy configurations even though the particle current tends to zero as the temperature reaches zero. That is because the dynamical activity that sets the effective time scale, also goes to zero with temperature. The result is a non-trivial asymptotic phase diagram, which crucially depends on the interaction coupling and the relative chemical potentials of the reservoirs.     

On the contribution of intramolecular H-bonding entropy to the conformational stability of alanine conformations

The experimental and theoretical rotamerization constants for the rotameric equilibrium between the two most stable conformations of the alpha-amino acid alanine are compared. The experimental technique of matrix-isolation Fourier transform infrared spectroscopy in combination with the density functional theory (DFT) (B3LYP) and the 6-31++G** basis set is used for this study. A large disagreement between the experimental and theoretical value of the equilibrium constant is found. A relatively strong intramolecular H-bond in conformation II is at the origin of this discrepancy. From the difference between the experimental and theoretical rotamerization constant, a DeltaS degrees value of -6.6 J K(-1) mol(-1) is found for the intramolecular H-bond formation.     

The vibrational spectra of E-1,2-bis(3-methoxy-2-thienyl)ethene in the crystalline phase

Density functional theoretical (DFT) calculations using the 6-311+G* basis set were carried out to study the vibrational spectrum of E-1,2-bis(3-methoxy-2-thienyl)ethene in the solid state. Based on the calculated frequencies, infrared intensities and potential energy distributions (PED), the experimental IR and Raman spectra of the solid phase were assigned.