25 research outputs found
Enhanced predictor–corrector Mars entry guidance approach with atmospheric uncertainties
Due to the long-range data communication and complex Mars environment, the Mars lander needs to promote the ability to autonomously adapt uncertain situations ensuring high precision landing in future Mars missions. Based on the analysis of multiple disturbances, this study demonstrates an enhanced predictor–corrector guidance method to deal with the effect of atmospheric uncertainties during the entry phase of the Mars landing. In the proposed method, the predictor–corrector guidance algorithm is designed to autonomously drive the Mars lander to the parachute deployment. Meanwhile, the disturbance observer is designed to onboard estimate the effect of fiercely varying atmospheric uncertainties resulting from rapidly height decreasing. Then, with the estimation of atmospheric uncertainties compensated in the feed-forward channel, the composite guidance method is put forward such that both anti-disturbance and autonomous performance of the Mars lander guidance system are improved. Convergence of the proposed composite method is analysed. Simulations for a Mars lander entry guidance system demonstrates that the proposed method outperforms the baseline method in consideration of the atmospheric uncertainties
第791回 千葉医学会例会・第22回 麻酔科例会・第44回 千葉麻酔懇話会 9.
Correlations of plasma PIM-1 levels and clinicopathological parameters. (XLSX 11 kb
Unusual Intramolecular Hydrogen Transfer in 3,5-Di(triphenylethylenyl) BODIPY Synthesis and 1,2-Migratory Shift in Subsequent Scholl Type Reaction
The straightforward synthesis of
3,5-di(triphenylethylenyl)
BODIPYs <b>1</b>–<b>3</b> from the condensation
of 2-(triphenylethylenyl) pyrrole with aryl aldehydes are surprisingly
found to produce side products that are hydrogenated at one of the
two triphenylethylene substituents. It was also observed that the
subsequent Scholl type reaction of <b>1</b> resulted in a “1,2-migratory
shift” of one triphenylethylene substituent in addition
to a ring closing reaction. Preliminary investigations, including
DFT calculations and isolation of intermediates, were conducted to
study these unusual observations on BODIPY chemistry
Unusual Intramolecular Hydrogen Transfer in 3,5-Di(triphenylethylenyl) BODIPY Synthesis and 1,2-Migratory Shift in Subsequent Scholl Type Reaction
The straightforward synthesis of
3,5-di(triphenylethylenyl)
BODIPYs <b>1</b>–<b>3</b> from the condensation
of 2-(triphenylethylenyl) pyrrole with aryl aldehydes are surprisingly
found to produce side products that are hydrogenated at one of the
two triphenylethylene substituents. It was also observed that the
subsequent Scholl type reaction of <b>1</b> resulted in a “1,2-migratory
shift” of one triphenylethylene substituent in addition
to a ring closing reaction. Preliminary investigations, including
DFT calculations and isolation of intermediates, were conducted to
study these unusual observations on BODIPY chemistry
How to Fabricate a Surface-Grafted Polythiophene on H‑Si(100)2×1 Surface via Self-Assembling and in Situ Surface Polymerization: A Theoretical Guide
Based on density
functional theory calculations, we have studied
the self-assembled growth of thiophene substituted alkenes, [H<sub>2</sub>CCH-(CH<sub>2</sub>)<sub><i>n</i></sub>-thiophene]
on hydrogen-terminated H-Si(100)2×1 and H-Ge(100)2×1 surfaces
into aligned one-dimensional (1D) molecular arrays which are chemically
bonded to the surfaces via the alkane chain. The thiophene rings at
the top end of the molecular arrays are situated side by side and
can undergo an in situ polymerization reaction into polythiophene
once radicals are introduced to the thiophene rings, thereby forming
polyalkylthiophene-Si/Ge(100)2×1 surface-grafted polymers. Like
most of conductive polymers, these surface single polymer chains exhibit
semiconducting character and can be made conductive either by p-doping
or by applying an external electric field. More importantly, both
surface-grafted polymers and substrates retain their electrical properties,
and the polythiophene chains are the sole conductive channels in the
structures. Our findings put forth a new way to fabricate conductive
polymeric molecular wires on traditional semiconducting substrates,
and could find potential application in nanoelectronic devices
Sulfonic Acid- and Lithium Sulfonate-Grafted Poly(Vinylidene Fluoride) Electrospun Mats As Ionic Liquid Host for Electrochromic Device and Lithium-Ion Battery
Electrospun polymer nanofibrous mats
loaded with ionic liquids
(ILs) are promising nonvolatile electrolytes with high ionic conductivity.
The large cations of ILs are, however, difficult to diffuse into solid
electrodes, making them unappealing for application in some electrochemical
devices. To address this issue, a new strategy is used to introduce
proton conduction into an IL-based electrolyte. Poly(vinylidene fluoride<b>-</b>co<b>-</b>hexafluoropropylene) (P(VDF-HFP)) copolymer
is functionalized with sulfonic acid through covalent attachment of
taurine. The sulfonic acid-grafted P(VDF-HFP) electrospun mats consist
of interconnected nanofibers, leading to remarkable improvement in
dimensional stability of the mats. IL-based polymer electrolytes are
prepared by immersing the modified mats in 1-butyl-3-methylimidazolium
tetrafluoroborate (BMIM<sup>+</sup>BF<sub>4</sub><sup>–</sup>). It is found that the SO<sub>3</sub><sup>–</sup> groups
can have Lewis acid–base interactions with the cations (BMIM<sup>+</sup>) of IL to promote the dissociation of ILs, and provide additional
proton conduction, resulting in significantly improved ionic conductivity.
Using this novel electrolyte, polyaniline-based electrochromic devices
show higher transmittance contrast and faster switching behavior.
Furthermore, the sulfonic acid-grafted P(VDF-HFP) electrospun mats
can also be lithiated, giving additional lithium ion conduction for
the IL-based electrolyte, with which Li/LiCoO<sub>2</sub> batteries
display enhanced C-rate performance
Sheet-Like Lignin Particles as Multifunctional Fillers in Polypropylene
Lignin is an attractive renewable
reinforcing agent for polyolefins
and also a promising low-cost antioxidant for polymers. It, however,
exhibits poor compatibility with nonpolar polymers. In this work,
alkali lignin was freeze-dried to achieve sheet-like morphology and
then incorporated into polypropylene (PP) by melt compounding. Owing
to the significantly increased interfacial area and improved dispersion,
with the addition of only 2 wt % freeze-dried lignin, the PP/lignin
composites show much enhanced tensile mechanical properties, including
a moderately improved Young’s modulus and almost doubled elongation
at break compared with those of neat PP. The enhancements brought
by the sheet-like lignin are far more impressive than those achieved
with the same amount of as-received lignin. The composites with the
freeze-dried lignin also have rough fractured surfaces with fiber
pull-out near the interface, revealing a significant toughening effect
of the lignin, which can be attributed to the crazing near the interface,
and enhanced relaxation in PP-lignin interphase as evidenced by the
reduced <i>T</i><sub>g</sub>. Furthermore, the large interfacial
area also drastically improves the antioxidant effect of lignin, greatly
slowing the UV-induced and thermo-oxidative degradation of PP. After
2 weeks of intense UV exposure, neat PP becomes very brittle with
its yield strain reduced to about 37% of its original value, whereas
the yield strain of the composite with 2 wt % sheet-like lignin is
almost unchanged, demonstrating the excellent free-radical scavenger
effect of the lignin
Cyclization of Tetraaryl-Substituted Benzoquinones and Hydroquinones through the Scholl Reaction
2,3,5,6-Tetrakis(5′-dodecylthiophen-2-yl)-benzoquinones
and 2,3,5,6-tetrakis(5′-dodecylthiophen-2′-yl)-hydroquinones
were prepared via the Stille or Suzuki cross-coupling reactions, followed
by oxidation by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in
the case that aryl groups are dodecylthiophenyl. 2,3,5,6-Tetrakis(5′-dodecylthiophen-2′-yl)benzoquinone
and 2,3,5,6-tetrakis(5′-dodecylthiophen-2′-yl)-1,4-bis(dodecyloxy)benzene
underwent the Scholl reaction to give their corresponding predictable
cyclization products anthra[2,1-<i>b</i>:3,4-<i>b</i>′:6,5-<i>b</i>″:7,8-<i>b</i>‴]tetrathiophene-7,14-dione
(<b>3</b>) and anthra[1,2-<i>b</i>:4,3-<i>b</i>′:5,6-<i>b</i>″:8,7-<i>b</i>‴]tetrathiophene
(<b>5</b>), respectively. Cyclization of 2,3,4,5-tetra(<i>p</i>-<i>tert</i>-butyl-phenyl) benzoquinones through
the Scholl reaction, however, gave rise to a mixture of two cyclization
products including an unusual major product, benzo[4′,5′]furo[3′,2′:3,4]triphenyleno[1,2-<i>b</i>]benzofuran (<b>9</b>), with 84% yield and a minor
product, 2,3-diphenyltriphenylene-1,4-diol (<b>10</b>), with
11% yield. In contrast, cyclization of 2,3,4,5-tetrakis(<i>p</i>-dodecyloxyphenyl)benzoquinone only afforded 2,3-diphenyltriphenylene-1,4-diol
(<b>8</b>) with 34% yield. The optical and electrochemistry
properties of these fused aromatics were studied. Light emitting diode
devices using compound <b>9</b> as the fluorescent dopant were
fabricated. A maximum external quantum efficiency of 3.23% was achieved
for a 4,4′-bis(carbazole)biphenyl/<b>9</b> based device,
revealing the potential for such fused aromatics as dopant to be a
blue LED component, subject to the functionalization on these novel
π-structures as well as further device optimization
Cyclization of Tetraaryl-Substituted Benzoquinones and Hydroquinones through the Scholl Reaction
2,3,5,6-Tetrakis(5′-dodecylthiophen-2-yl)-benzoquinones
and 2,3,5,6-tetrakis(5′-dodecylthiophen-2′-yl)-hydroquinones
were prepared via the Stille or Suzuki cross-coupling reactions, followed
by oxidation by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in
the case that aryl groups are dodecylthiophenyl. 2,3,5,6-Tetrakis(5′-dodecylthiophen-2′-yl)benzoquinone
and 2,3,5,6-tetrakis(5′-dodecylthiophen-2′-yl)-1,4-bis(dodecyloxy)benzene
underwent the Scholl reaction to give their corresponding predictable
cyclization products anthra[2,1-<i>b</i>:3,4-<i>b</i>′:6,5-<i>b</i>″:7,8-<i>b</i>‴]tetrathiophene-7,14-dione
(<b>3</b>) and anthra[1,2-<i>b</i>:4,3-<i>b</i>′:5,6-<i>b</i>″:8,7-<i>b</i>‴]tetrathiophene
(<b>5</b>), respectively. Cyclization of 2,3,4,5-tetra(<i>p</i>-<i>tert</i>-butyl-phenyl) benzoquinones through
the Scholl reaction, however, gave rise to a mixture of two cyclization
products including an unusual major product, benzo[4′,5′]furo[3′,2′:3,4]triphenyleno[1,2-<i>b</i>]benzofuran (<b>9</b>), with 84% yield and a minor
product, 2,3-diphenyltriphenylene-1,4-diol (<b>10</b>), with
11% yield. In contrast, cyclization of 2,3,4,5-tetrakis(<i>p</i>-dodecyloxyphenyl)benzoquinone only afforded 2,3-diphenyltriphenylene-1,4-diol
(<b>8</b>) with 34% yield. The optical and electrochemistry
properties of these fused aromatics were studied. Light emitting diode
devices using compound <b>9</b> as the fluorescent dopant were
fabricated. A maximum external quantum efficiency of 3.23% was achieved
for a 4,4′-bis(carbazole)biphenyl/<b>9</b> based device,
revealing the potential for such fused aromatics as dopant to be a
blue LED component, subject to the functionalization on these novel
π-structures as well as further device optimization
MiR-1178 Promotes the Proliferation, G1/S Transition, Migration and Invasion of Pancreatic Cancer Cells by Targeting CHIP
<div><p>CHIP, a co-chaperone protein that interacts with Hsc/Hsp70, has been shown to be under-expressed in pancreatic cancer cells and has demonstrated a potential tumor suppressor property. Nevertheless, the underlying mechanisms of CHIP regulation in pancreatic cancer cells remain unknown. In this study, we found that miR-1178 decreased the translation of the CHIP protein by targeting the 3′-UTR region. We observed that over-expression of miR-1178 facilitated the proliferation, G1/S transition, migration and invasion of pancreatic cancer cells. Conversely, the inhibition of miR-1178 expression significantly suppressed these phenotypes. Furthermore, CHIP over-expression abrogated miR-1178-induced cell proliferation and invasion. Our data suggest that miR-1178 acts as an oncomiR in pancreatic cancer cells by inhibiting CHIP expression.</p></div