A series of molecular dynamics (MD) simulations up to 1 μs for bovine insulin monomer in different external electric fields were carried out to study the effect of external electric field on conformational integrity of insulin. Our results show that the secondary structure of insulin is kept intact under the external electric field strength below 0.15 V/nm, but disruption of secondary structure is observed at 0.25 V/nm or higher electric field strength. Although the starting time of secondary structure disruption of insulin is not clearly correlated with the strength of the external electric field ranging between 0.15 and 0.60 V/nm, long time MD simulations demonstrate that the cumulative effect of exposure time under the electric field is a major cause for the damage of insulin's secondary structure. In addition, the strength of the external electric field has a significant impact on the lifetime of hydrogen bonds when it is higher than 0.60 V/nm. The fast evolution of some hydrogen bonds of bovine insulin in the presence of the 1.0 V/nm electric field shows that different microwaves could either speed up protein folding or destroy the secondary structure of globular proteins deponding on the intensity of the external electric field.

No abstract

Vertically oriented CuS nanowalls supported on a copper substrate have been synthesized through a facile method involving an inorganic vapour–solid phase reaction. The CuS nanowalls were well connected to form an extended network. The shapes of the CuS nanostructures could be controlled by adjusting the reaction conditions such as the reaction temperature and the flow rate of argon gas. The crystallinity of the nanowalls was investigated by XRD and their morphological features were characterized by FESEM. Both TEM and SAED analyses revealed that the nanowalls are single-crystalline. The field emission properties of the CuS nanowalls were investigated. The turn-on field and current density of the CuS nanowalls are comparable to those of many other semiconductor nanomaterials, which suggests that the CuS nanowalls may have potential applications in the vacuum microelectronics industry.

No abstract