8 research outputs found
Structural lubricity under ambient conditions.
Despite its fundamental importance, physical mechanisms that govern friction are poorly understood. While a state of ultra-low friction, termed structural lubricity, is expected for any clean, atomically flat interface consisting of two different materials with incommensurate structures, some associated predictions could only be quantitatively confirmed under ultra-high vacuum (UHV) conditions so far. Here, we report structurally lubric sliding under ambient conditions at mesoscopic (∼4,000-130,000 nm(2)) interfaces formed by gold islands on graphite. Ab initio calculations reveal that the gold-graphite interface is expected to remain largely free from contaminant molecules, leading to structurally lubric sliding. The experiments reported here demonstrate the potential for practical lubrication schemes for micro- and nano-electromechanical systems, which would mainly rely on an atomic-scale structural mismatch between the slider and substrate components, via the utilization of material systems featuring clean, atomically flat interfaces under ambient conditions
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Structural lubricity under ambient conditions.
Despite its fundamental importance, physical mechanisms that govern friction are poorly understood. While a state of ultra-low friction, termed structural lubricity, is expected for any clean, atomically flat interface consisting of two different materials with incommensurate structures, some associated predictions could only be quantitatively confirmed under ultra-high vacuum (UHV) conditions so far. Here, we report structurally lubric sliding under ambient conditions at mesoscopic (∼4,000-130,000 nm(2)) interfaces formed by gold islands on graphite. Ab initio calculations reveal that the gold-graphite interface is expected to remain largely free from contaminant molecules, leading to structurally lubric sliding. The experiments reported here demonstrate the potential for practical lubrication schemes for micro- and nano-electromechanical systems, which would mainly rely on an atomic-scale structural mismatch between the slider and substrate components, via the utilization of material systems featuring clean, atomically flat interfaces under ambient conditions
Antibacterial electrospun zein nanofibrous web encapsulating thymol/cyclodextrin-inclusion complex for food packaging
Thymol (THY)/gamma-Cyclodextrin(gamma-CD) inclusion complex (IC)
encapsulated electrospun zein nanofibrous webs (zein-THY/gamma-CD-IC-NF)
were fabricated as a food packaging material. The formation of
THY/gamma-CD-IC (1:1 and 2:1) was proved by experimental (X-ray
diffraction (XRD), thermal gravimetric analysis (TGA), H-1 NMR) and
computational techniques. THY/gamma-CD-IC (2:1) exhibited higher
preservation rate and stability than THY/gamma-CD-IC (1:1). It is worth
mentioning that zein-THY/gamma-CD-IC-NF (2:1) preserved much more THY as
observed in TGA and stability of THY/gamma-CD-IC (2:1) was higher, as
shown by a modelling study. Therefore, much more THY was released from
zein-THY/gamma-CD-IC-NF (2:1) than zein-THY-NF and
zein-THY/gamma-CD-IC-NF (1:1). Similarly, antibacterial activity of
zein-THY/gamma-CD-IC-NF (2:1) was higher than zein-THY-NF and
zein-THY/gamma-CD-IC-NF (1:1). It was demonstrated that
zein-THY/gamma-CD-IC-NF (2:1) was most effective in inhibiting the
growth of bacteria on meat samples. These webs show potential
application as an antibacterial food packaging material. (C) 2017
Elsevier Ltd. All rights reserved
Fast-Dissolving, Prolonged Release, and Antibacterial Cyclodextrin/Limonene-Inclusion Complex Nanofibrous Webs via Polymer-Free Electrospinning
We have proposed a new strategy for preparing free-standing nanofibrous
webs from an inclusion complex (IC) of a well-known flavor/fragrance
compound (limonene) with three modified cyclodextrins (HP beta CD, M
beta CD, and HP gamma CD) via electrospinning (CD/limonene-IC-NFs)
without using a polymeric matrix. The experimental and computational
modeling studies proved that the stoichiometry of the complexes was 1:1
for CD/limonene systems. M beta CD/limonene-IC-NF released much more
limonene at 37, 50, and 75 degrees C than HP beta CD/limonene-IC-NF and
HP gamma CD/limonene-IC-NF because of the greater amount of preserved
limonene. Moreover, M beta CD/limonene-IC-NF has released only 25\%
(w/w) of its limonene, whereas HP beta CD/limonene-IC-NF and HP gamma
CD/limonene-IC-NF released 51 and 88\% (w/w) of their limonene in 100
days, respectively. CD/limonene-IC-NFs exhibited high antibacterial
activity against E. coli and S. aureus. The water solubility of limonene
increased significantly and CD/limonene-IC-NFs were dissolved in water
in a few seconds. In brief, CD/limonene-IC-NFs with fast dissolving
character enhanced the thermal stability and prolonged the shelf life
along with antibacterial properties could be quite applicable in food
and oral care applications
Fast-Dissolving, Prolonged Release, and Antibacterial Cyclodextrin/Limonene-Inclusion Complex Nanofibrous Webs via Polymer-Free Electrospinning
We
have proposed a new strategy for preparing free-standing nanofibrous
webs from an inclusion complex (IC) of a well-known flavor/fragrance
compound (limonene) with three modified cyclodextrins (HPβCD,
MβCD, and HPγCD) via electrospinning (CD/limonene-IC-NFs)
without using a polymeric matrix. The experimental and computational
modeling studies proved that the stoichiometry of the complexes was
1:1 for CD/limonene systems. MβCD/limonene-IC-NF released much
more limonene at 37, 50, and 75 °C than HPβCD/limonene-IC-NF
and HPγCD/limonene-IC-NF because of the greater amount of preserved
limonene. Moreover, MβCD/limonene-IC-NF has released only 25%
(w/w) of its limonene, whereas HPβCD/limonene-IC-NF and HPγCD/limonene-IC-NF
released 51 and 88% (w/w) of their limonene in 100 days, respectively.
CD/limonene-IC-NFs exhibited high antibacterial activity against <i>E. coli</i> and <i>S. aureus</i>. The water solubility
of limonene increased significantly and CD/limonene-IC-NFs were dissolved
in water in a few seconds. In brief, CD/limonene-IC-NFs with fast-dissolving
character enhanced the thermal stability and prolonged the shelf life
along with antibacterial properties could be quite applicable in food
and oral care applications