21 research outputs found
Advanced Performance of Annealed Ni-P/(Etched Si) Negative Electrodes for Lithium-Ion Batteries
The electrochemical performance of variously treated Ni-P-coated Si (Ni-P/Si) negative electrodes for lithium-ion batteries was investigated. X-ray diffraction analysis revealed the formation of nickel silicide (NiSi and NiSi2) after annealing, which improved the adhesion between the Ni-P coating layer and Si particles. Spotty Ni-P particles did not aggregate on an etched Si surface due to an anchor effect, even after annealing, whereas the particles aggregated on an untreated Si surface. An annealed Ni-P/(etched Si) negative electrode maintained a discharge capacity of 2000 mA h g-1 even at the 100th cycle in an organic electrolyte, which can be attributed to Ni-P particles remaining on the surface of the annealed Ni-P/(etched Si) electrode even after the charge-discharge test. The annealed Ni-P/(etched Si) electrode also exhibited superior cycle performance with a reversible capacity of 1000 mA h g-1 over 750 and 1100 cycles in an organic electrolyte containing film-forming additive and an ionic liquid electrolyte, respectively. Consequently, the annealed Ni-P/(etched Si) electrode achieved both high reversible capacity and long cycle life
Autonomous Sequences in Myoglobin Emerging from X‑ray Structure of Holomyoglobin
The proposed continuous folding structure
units are fundamental
to analyze protein structure. Here, we could elucidate for the first
time two types of hydrophobic core networks in apomyoglobin using
continuous folding structure units. In myoglobin, two autonomous sequences
emerged clearly. We could thus characterize the autonomous sequences
using well-defined hydrophobic core networks within respective semifolds.
A hydrophobic core is defined as a pair of topology-local hydrophobic
amino acids in different folding structures. Hydrophobic core formation
is indispensable to stabilize the different folding structures via
an efficient hydrophobic interaction. Autonomous sequences in myoglobin
encode tertiary structure information for semifolds. These sequences
fold autonomously into small sets of continuous folding structure
units to grow separate semifolds on each separate framework. The autonomous
sequence can be defined as the local sequence assigned to the small
set of continuous folding structure units. They create the discrete
hydrophobic region in a semifold by assembly of their hydrophobic
regions. Semifolds were characterized by discrete hydrophobic regions
stabilized by respective type I hydrophobic core networks, which were
present within each semifold. The discrete hydrophobic region of a
semifold propagated itself with that of a different semifold by hydrophobic
interactions in type II hydrophobic core network, which was present
between different semifolds, as observed by the X-ray structures of
semifolds. The most significant feature of semifolds in apomyoglobin
was that they could be verified by the X-ray structure of holomyoglobin
regardless of the instability of folds characteristic to autonomous
sequence fragments. This work presents the first description of autonomous
sequences
Protein Folding Structures: Formation of Folding Structures Based on Probability Theory
To the best of our knowledge, this is the first study that shows
that the X-ray structures of proteins can be dissected into their
continuous folding structure units. Each folding structure unit was
designed such that both the terminal di- or tri-peptide sequences
shared common sequences with the two adjacent folding structure units.
To encode the folding structure information of proteins into their
amino acid sequences, we proposed 44 kinds of folding elements, which
covered all of the amino acids in the protein chains, and defined
all folding structure units. The folding element was defined to mean
a minimum structural piece, which covered the frame of the main chain
of each amino acid in a protein chain. A folding structure unit of
a local sequence could be fully characterized by the sequential combination
of individual folding elements assigned to each amino acid. The folding
structure information showed amino acid preferences in various positions
in folding structure units.
Folding structure formation proceeded on the basis of probability
theory. Strikingly, relative formation ability analysis clearly indicated
that we can decode the types and the chain length of folding structure
units from the amino acid sequence of a protein