Effect of laser-induced ultrasound treatment on material structure in laser surface treatment for selective laser melting applications.

A new mechanism for controlling the microstructure of products in manufacturing processes based on selective laser melting is proposed. The mechanism relies on generation of high-intensity ultrasonic waves in the melt pool by complex intensity-modulated laser irradiation. The experimental study and numerical modeling suggest that this control mechanism is technically feasible and can be effectively integrated into the design of modern selective laser melting machines.

Membrane Position Dependency of the pK and Conductivity of the Protein Ion Channel.

The dependency of current-voltage characteristics of the α-hemolysin channel on the channel position within the membrane was studied using Poisson-Nernst-Planck theory of ion conductivity with soft repulsion between mobile ions and protein atoms (SP-PNP). The presence of the membrane environment also influences the protonation state of the residues at the boundary of the water-lipid interface. In this work, we predict that Asp and Lys residues at the protein rim change their protonation state upon penetration to the lipid environment.

A Distal Disulfide Bridge in OXA-1 β-Lactamase Stabilizes the Catalytic Center and Alters the Dynamics of the Specificity Determining Ω Loop.

Widespread antibiotic resistance, particularly when mediated by broad-spectrum β-lactamases, has major implications for public health. Substitutions in the active site often allow broad-spectrum enzymes to accommodate diverse types of β-lactams. Substitutions observed outside the active site are thought to compensate for the loss of thermal stability.

Homolytic Cleavage of Both Heme-Bound Hydrogen Peroxide and Hydrogen Sulfide Leads to the Formation of Sulfheme.

Many heme-containing proteins with a histidine in the distal E7 (HisE7) position can form sulfheme in the presence of hydrogen sulfide (H2S) and a reactive oxygen species such as hydrogen peroxide. For reasons unknown, sulfheme derivatives are formed specifically on solvent-excluded heme pyrrole B. Sulfhemes severely decrease the oxygen-binding affinity in hemoglobin (Hb) and myoglobin (Mb).

pH-triggered conformational switching of the diphtheria toxin T-domain: the roles of N-terminal histidines.

pH-induced conformational switching is essential for functioning of diphtheria toxin, which undergoes a membrane insertion/translocation transition triggered by endosomal acidification as a key step of cellular entry. In order to establish the sequence of molecular rearrangements and side-chain protonation accompanying the formation of the membrane-competent state of the toxin's translocation (T) domain, we have developed and applied an integrated approach that combines multiple techniques of computational chemistry [e.g.

Soft wall ion channel in continuum representation with application to modeling ion currents in α-hemolysin.

A soft repulsion (SR) model of short-range interactions between mobile ions and protein atoms is introduced in the framework of continuum representation of the protein and solvent. The Poisson-Nernst-Plank (PNP) theory of ion transport through biological channels is modified to incorporate this soft wall protein model. Two sets of SR parameters are introduced.

Effect of lipid composition on the "membrane response" induced by a fusion peptide.

To understand the initial stages of membrane destabilization induced by viral proteins, the factors important for binding of fusion peptides to cell membranes must be identified. In this study, effects of lipid composition on the mode of peptides' binding to membranes are explored via molecular dynamics (MD) simulations of the peptide E5, a water-soluble analogue of influenza hemagglutinin fusion peptide, in two full-atom hydrated lipid bilayers composed of dimyristoyl- and dipalmitoylphosphatidylcholine (DMPC and DPPC, respectively). The results show that, although the peptide has a common folding motif in both systems, it possesses different modes of binding.