36 research outputs found
Schematic depiction of location of the introduced stop codons for stop –codon scanning assay and RNAse protection assay results.
No full text<p>All nucleotide numbers are given respective to the annotated start codon at +1. Position −450 is the predicted transcribed but not translated region of <i>HFA1</i>. The underlined region up to position −216 region shows the putative minimum mitochondrial import sequence and upstream position −141 shows the end of the sequence similarity to <i>ACC1</i>. The ORFof <i>HFA1</i> annotated in the <i>Saccharomyces</i> Genome Database starts from +1. The stop codon found to lead to a respiratory deficient phenotype in the screen performed by Kursu <i>et al</i>. 2013 is located at −273 and 8 more stop codons at −282, −312, −360, −363, −372 −375 −378 and −381 were introduced upstream in the promoter region of <i>HFA1</i>.</p
Generation of Long-Lived Redox Equivalents in Self-Assembled Bilayer Structures on Metal Oxide Electrodes
No full textWe report on the
synthesis and photophysical properties of a photocathode
consisting of a molecular bilayer structure self-assembled on p-type
NiO nanostructured films. The resulting photocathode and its nanostructured
indium–tin oxide analog absorb visible light and convert it
into injected holes with injection yields of ∼30%, measured
at the first observation time by nanosecond transient absorption spectroscopy,
and long-lived reducing equivalents that last for several milliseconds
without applied bias. An initial quantum yield of 15% was achieved
for photogeneration of the reduced dye on the p-NiO electrode. Nanosecond
transient absorption experiments and detailed analyses of the underlying
electron transfer steps demonstrate that the overall efficiency of
the cell is limited by hole injection and charge recombination processes.
Compared with the highly doped indium–tin oxide photocathode,
the NiO photocathode shows superior photoconversion efficiencies for
generating reducing equivalents and longer lifetimes of surface-bound
redox-separated states due to an inhibition toward charge recombination
with the external assembly
Reaction-Environment-Dependent Photoaddition Reactions of <i>N</i>‑Phenyl Amino Acid Esters Possessing a Silyl Group with Fullerene C<sub>60</sub>: Selective Formation of Aminomethyl-1,2-dihydrofullerenes vs Fulleropyrrolidines
No full textThe current study investigates SET-promoted photoaddition
reactions
of the silyl-group-containing N-phenylglycinates
and N-phenylalaninates, N-((trimethylsilyl)methyl)-N-phenyl-substituted glycinates and alaninates, respectively,
with fullerene C60 to explore how the types of amino acid
esters (AAEs) and molecular oxygen affect the photoaddition reaction
efficiencies and chemoselectivity of in situ formed radical cations
of AAEs. The results showed that under deoxygenated (N2-purged) conditions, photoreactions of N-phenylglycinates
with C60 produced aminomethyl-1,2-dihydrofullerenes through
the addition of α-amino radicals arising by sequential SET and
desilylation processes from initially formed secondary anilines to
C60. In oxygenated conditions, photoreactions of N-phenylglycinates with C60, albeit less efficient,
took place to form fulleropyrrolidines through a pathway involving
1,3-dipolar cycloaddition of azomethine ylides to C60 assisted
by in situ formed 1O2. The same types of photoproducts
were observed with N-phenylalaninates, though the
reactions were less efficient. The use of methylene blue (MB) as a
photosensitizer in the photoreactions under oxygenated conditions
was especially effective in enhancing the efficiency of fulleropyrrolidine
formation. These results demonstrate that photoaddition reactions
of silyl-tether-containing N-phenyl AAEs with C60 can be governed by the reaction conditions and the presence
or absence of a photosensitizer employed
Bis(4-(4,5-diphenyl-4H-1,2,4-triazol-3-yl)phenyl)dimethylsilane as Electron-Transport Material for Deep Blue Phosphorescent OLEDs
No full textBis(4-(4,5-diphenyl-4H-1,2,4-triazol-3-yl)phenyl)dimethylsilane (<b>SiTAZ</b>) was designed and synthesized as an electron-transporting material for deep blue phosphorescent organic light-emitting devices (PHOLEDs). Introducing a Si atom between two 3,4,5-triphenyl-1,2,4-triazole molecules, a high triplet energy of 2.84 eV, high glass transition temperature of 115 °C, and high electron mobility of 6.2 × 10<sup>−4</sup> cm<sup>2</sup> V<sup>−1</sup> s<sup>−1</sup> were achieved. By employing <b>SiTAZ</b> as a hole-blocking and electron-transporting material of iridium(III)[bis(4,6-difluorophenyl)pyridinato-<i>N</i>,C<sup>2</sup>′]tetrakis(1-pyrazolyl)borate (FIr6)-based deep blue phosphorescent OLEDs, a maximum external quantum efficiency (EQE) of 15.5%, an EQE of 13.8% at high luminance of 1000 cd m<sup>−2</sup>, and deep blue color coordinates of (0.16, 0.22) were achieved. The reduced efficiency roll-off at high luminance was attributed to the high triplet energy of the <b>SiTAZ</b>
Robust sliding mode control for discrete stochastic systems with mixed time delays, randomly occurring uncertainties, and randomly occurring nonlinearities
No full textThis is the post-print version of the paper. The official published version can be accessed from the link below - Copyright @ 2012 IEEEThis paper investigates the robust sliding mode control (SMC) problem for a class of uncertain nonlinear stochastic systems with mixed time delays. Both the sectorlike nonlinearities and the norm-bounded uncertainties enter into the system in random ways, and such randomly occurring uncertainties and randomly occurring nonlinearities obey certain mutually uncorrelated Bernoulli distributed white noise sequences. The mixed time delays consist of both the discrete and the distributed delays. The time-varying delays are allowed in state. By employing the idea of delay fractioning and constructing a new Lyapunov–Krasovskii functional, sufficient conditions are established to ensure the stability of the system dynamics in the specified sliding surface by solving a certain semidefinite programming problem. A full-state feedback SMC law is designed to guarantee the reaching condition. A simulation example is given to demonstrate the effectiveness of the proposed SMC scheme.This work was supported in part by the National Natural Science Foundation of China under Grants 61028008, 60825303 and 60834003, National 973 Project under Grant 2009CB320600, the Fok Ying Tung Education Fund under Grant 111064, the Special Fund for the Author of National Excellent Doctoral Dissertation of China under Grant 2007B4, the Key Laboratory of Integrated Automation for the Process Industry Northeastern University) from the Ministry of Education of China, the Engineering and Physical Sciences Research Council (EPSRC) of the U.K. under Grant GR/S27658/01, the Royal Society of the U.K., and the Alexander von Humboldt Foundation of Germany
Reaction-Environment-Dependent Photoaddition Reactions of <i>N</i>‑Phenyl Amino Acid Esters Possessing a Silyl Group with Fullerene C<sub>60</sub>: Selective Formation of Aminomethyl-1,2-dihydrofullerenes vs Fulleropyrrolidines
No full textThe current study investigates SET-promoted photoaddition
reactions
of the silyl-group-containing N-phenylglycinates
and N-phenylalaninates, N-((trimethylsilyl)methyl)-N-phenyl-substituted glycinates and alaninates, respectively,
with fullerene C60 to explore how the types of amino acid
esters (AAEs) and molecular oxygen affect the photoaddition reaction
efficiencies and chemoselectivity of in situ formed radical cations
of AAEs. The results showed that under deoxygenated (N2-purged) conditions, photoreactions of N-phenylglycinates
with C60 produced aminomethyl-1,2-dihydrofullerenes through
the addition of α-amino radicals arising by sequential SET and
desilylation processes from initially formed secondary anilines to
C60. In oxygenated conditions, photoreactions of N-phenylglycinates with C60, albeit less efficient,
took place to form fulleropyrrolidines through a pathway involving
1,3-dipolar cycloaddition of azomethine ylides to C60 assisted
by in situ formed 1O2. The same types of photoproducts
were observed with N-phenylalaninates, though the
reactions were less efficient. The use of methylene blue (MB) as a
photosensitizer in the photoreactions under oxygenated conditions
was especially effective in enhancing the efficiency of fulleropyrrolidine
formation. These results demonstrate that photoaddition reactions
of silyl-tether-containing N-phenyl AAEs with C60 can be governed by the reaction conditions and the presence
or absence of a photosensitizer employed
Electron Push–Pull Effects in 3,9-Bis(<i>p</i>‑(R)-diphenylamino)perylene and Constraint on Emission Color Tuning
No full textA series
of perylene-based donor–acceptor–donor (D–A–D)
compounds, 3,9-bis(p-(R)-diphenylamino)perylene (R:
CN (2a), F (2b), H (2c), Me
(2d), and OMe (2e)), was synthesized using
3,9-dibromoperylene with p-(R)-diphenylamine, and
the intramolecular charge transfer (ICT) on the D–A–D
system with regard to the electron push–pull substituent effect
was investigated. By introducing various p-(R)-diphenylamine
derivatives with electron-donating or electron-withdrawing R groups,
the energy band gaps of the D–A–D compounds were systematically
controlled and the emission colors were efficiently tuned from green
to red. As expected, the steady state emission spectra of all D–A–D
compounds were observed, as well as the emission color controlled,
depending on the Hammett substituent constants (σp). In the Lippert–Mataga plots, a different charge-transfer
character was observed depending on the electron push–pull
substitution, which showed gradually increased ICT characters from
the electron-withdrawing to donating substitution. However, exceptionally,
the strong electron-withdrawing group of CN-substituted 2a did not correlate with the other R group compounds. From the experimental
data and density functional theory calculations, we assume that there
is a constraint on emission color tuning to generate higher energy
of blue emission in the D–A–D molecular system, due
to the reverse charge-transfer property caused by the strong electron-withdrawing
group
Stabilization of Ruthenium(II) Polypyridyl Chromophores on Nanoparticle Metal-Oxide Electrodes in Water by Hydrophobic PMMA Overlayers
No full textWe describe a poly(methyl methacrylate)
(PMMA) dip-coating procedure,
which results in surface stabilization of phosphonate and carboxylate
derivatives of Ru(II)-polypyridyl complexes surface-bound to mesoporous
nanoparticle TiO2 and nanoITO films in aqueous solutions.
As shown by contact angle and transmission electron microscopy (TEM)
measurements, PMMA oligomers conformally coat the metal-oxide nanoparticles
changing the mesoporous films from hydrophilic to hydrophobic. The
thickness of the PMMA overlayer on TiO2–Ru(II) can
be controlled by changing the wt % of PMMA in the dipcoating solution.
There are insignificant perturbations in electrochemical or spectral
properties at thicknesses of up to 2.1 nm with the Ru(III/II) couple
remaining electrochemically reversible and E1/2 values and current densities nearly unaffected. Surface
binding by PMMA overlayers results in stable surface binding even
at pH 12 with up to a ∼100-fold enhancement in photostability.
As shown by transient absorption measurements, the MLCT excited state(s)
of phosphonate derivatized [Ru(bpy)2((4,4′-(OH)2PO)2bpy)]2+ undergo efficient injection
and back electron transfer with pH independent kinetics characteristic
of the local pH in the initial loading solution
Carborane-Based Optoelectronically Active Organic Molecules: Wide Band Gap Host Materials for Blue Phosphorescence
No full textCarborane-based host materials were prepared to fabricate
deep
blue phosphorescence organic light-emitting diodes (PHOLEDs), which
constituted three distinctive geometrical structures stemming from
the corresponding three different isomeric forms of carboranes, namely, ortho-, meta-, and para-carboranes. These materials consist of two carbazolyl phenyl (CzPh)
groups as photoactive units on each side of the carborane carbons
to be bis[4-(N-carbazolyl)phenyl]carboranes, o-Cb, m-Cb,
and p-Cb. To elaborate on the role of
the carboranes, comparative analogous benzene series (o-Bz, m-Bz, and p-Bz) were prepared, and their photophysical
properties were compared to show that advantageous photophysical properties
were originated from the carborane structures: high triplet energy.
Unlike m-Bz and p-Bz, carborane-based m-Cb and p-Cb showed an unconjugated nature between
two CzPh units, which is essential for the blue phosphorescent materials.
Also, the carborane hosts showed high glass transition temperatures
(Tg) of 132 and 164 °C for m-Cb and p-Cb, respectively. Albeit p-Cb exhibited
slightly lower hole mobility when compared to p-Bz, it still lies at the high end hole mobility with a value
of 1.1 × 10–3 cm2/(V s) at an electric
field of 5 × 105 V/cm. Density functional theory (DFT)
calculations revealed that triplet wave functions were effectively
confined and mostly located at either side of the carbazolyl units
for m-Cb and p-Cb. Low-temperature PL spectra indeed provided unequivocal
data with higher triplet energy (T1) of
3.1 eV for both m-Cb and p-Cb. p-Cb was successfully
used as a host in deep blue PHOLEDs to provide a high external quantum
efficiency of 15.3% and commission internationale de l’elcairage
(CIE) coordinates of (0.15, 0.24)
Rational Design, Synthesis, and Characterization of Deep Blue Phosphorescent Ir(III) Complexes Containing (4′-Substituted-2′-pyridyl)-1,2,4-triazole Ancillary Ligands
No full textOn
the basis of the results of frontier orbital considerations, 4-substituted-2′-pyridyltriazoles
were designed to serve as ancillary ligands in 2-phenylpyridine main
ligand containing heteroleptic iridium(III) complexes that display
deep blue phosphorescence emission. The iridium(III) complexes, Ir1–Ir7, prepared using the new ancillary
ligands, were found to display structured, highly quantum efficient
(Φp = 0.20–0.42) phosphorescence with emission
maxima in the blue to deep blue 448–456 nm at room temperature.
In accord with predictions based on frontier orbital considerations,
the complexes were observed to have emission properties that are dependent
on the electronic nature of substituents at the C-4 position of the
pyridine moiety of the ancillary ligand. Importantly, placement of
an electron-donating methyl group at C-4′ of the pyridine ring
of the 5-(pyridine-2′-yl)-3-trifluoromethyl-1,2,4-triazole
ancillary ligand leads to an iridium(III) complex that displays a
deep blue phosphorescence emission maximum at 448 nm in both the liquid
and film states at room temperature. Finally, an OLED device, constructed
using an Ir-complex containing the optimized ancillary ligand as the
dopant, was found to emit deep blue color with a CIE of 0.15, 0.18,
which is close to the perfect goal of 0.15, 0.15
