110 research outputs found
Solution-Processable Low-Voltage and Flexible Floating-Gate Memories Based on an n‑Type Polymer Semiconductor and High‑<i>k</i> Polymer Gate Dielectrics
High-performance low-voltage flash
memories based on organic floating-gate field-effect transistors are
prepared by a solution process for the first time. Transistors with
a high-mobility n-type polymer semiconductor, polyÂ{[<i>N</i>,<i>N</i><sup>′</sup>-bisÂ(2-octyldodecyl)Ânaphthalene-1,4,5,8-bisÂ(dicarboximide)-2,6-diyl]-<i>alt</i>-5,5′-(2,2′-bithiophene)}, and a high-<i>k</i> polymer gate dielectric, polyÂ(vinylidene fluoride–trifluoroethylene–chlorofluoroethylene)
(<i>k</i> ≈ 60), are successfully fabricated on flexible
substrates. A thin layer of Au nanoparticles is embedded in the gate
dielectric, which can store injected charge from the channel and result
in a memory effect. The organic memories demonstrate high carrier
mobilities (>0.3 cm<sup>2</sup>/(V s)), low program/erase voltages
(±6 V), little degradation after 10<sup>5</sup> program/erase
cycles, and good retention after 10<sup>5</sup> s, which suggest great
promise in the application of nonvolatile memories in flexible electronics
Halobenzoquinone-Induced Alteration of Gene Expression Associated with Oxidative Stress Signaling Pathways
Halobenzoquinones
(HBQs) are emerging disinfection byproducts (DBPs)
that effectively induce reactive oxygen species and oxidative damage
in vitro. However, the impacts of HBQs on oxidative-stress-related
gene expression have not been investigated. In this study, we examined
alterations in the expression of 44 genes related to oxidative-stress-induced
signaling pathways in human uroepithelial cells (SV-HUC-1) upon exposure
to six HBQs. The results show the structure-dependent effects of HBQs
on the studied gene expression. After 2 h of exposure, the expression
levels of 9 to 28 genes were altered, while after 8 h of exposure,
the expression levels of 29 to 31 genes were altered. Four genes (<i>HMOX1</i>, <i>NQO1</i>, <i>PTGS2</i>, and <i>TXNRD1</i>) were significantly upregulated by all six HBQs at
both exposure time points. Ingenuity pathway analysis revealed that
the Nrf2 pathway was significantly responsive to HBQ exposure. Other
canonical pathways responsive to HBQ exposure included GSH redox reductions,
superoxide radical degradation, and xenobiotic metabolism signaling.
This study has demonstrated that HBQs significantly alter the gene
expression of oxidative-stress-related signaling pathways and contributes
to the understanding of HBQ-DBP-associated toxicity
Emerging Disinfection Byproducts, Halobenzoquinones: Effects of Isomeric Structure and Halogen Substitution on Cytotoxicity, Formation of Reactive Oxygen Species, and Genotoxicity
Halobenzoquinones (HBQs) are a structurally diverse class of water
disinfection byproducts. Here, we report a systematic study on the
effects of isomeric structure and the type and number of halogen substitutions
of HBQs on their cytotoxicity, formation of reactive oxygen species
(ROS), and genotoxicity. Dynamic responses and IC<sub>50</sub> histograms
were obtained using real-time cell analysis, clearly ranking the cytotoxicity
of the HBQs in Chinese hamster ovary (CHO-K1) cells. Strong isomeric
structure effects were shown with 2,5-HBQ isomers inducing greater
cytotoxicity than their corresponding 2,6-HBQ isomers (<i>P</i> < 0.05). HBQ-halogen substitution groups also influence cytotoxicity,
as cytotoxicity increases across the dihalogenated HBQs: iodo- > bromo-
> chloro-HBQs (<i>P</i> < 0.05). Determination of HBQ-induced
ROS further supports isomeric structure and halogen substitution effects.
HBQ-induced genotoxicity was shown as increased levels of 8-hydroxy-2′-deoxyguanosine
and p53 protein. Pearson correlation analysis of the HBQ toxicity
measurements with their physicochemical parameters demonstrates that
dipole moment and the lowest unoccupied molecular orbital energy are
two major structural influences on toxicity (<i>r</i> =
−0.721 or −0.766, <i>P</i> < 0.05). Dipole
moment also correlates with isomer toxicity. This study suggests that
formation and occurrence of highly toxic iodo-HBQs and 2,5-HBQs warrant
further investigation to fully assess the impact of HBQs in drinking
water
Interconversion between Ruthenacyclohexadiene and Ruthenabenzene: A Combined Experimental and Theoretical Study
Treatment of ruthenabenzene [(C<sub>9</sub>H<sub>6</sub>NO)ÂRuÂ{CCÂ(PPh<sub>3</sub>)ÂCHCÂ(PPh<sub>3</sub>)ÂCH}Â(C<sub>9</sub>H<sub>6</sub>NO)Â(PPh<sub>3</sub>)]ÂCl<sub>2</sub> (<b>1</b>) with NaBH<sub>4</sub> produces
the first ruthenacyclohexa-1,4-diene [(C<sub>9</sub>H<sub>6</sub>NO)ÂRuÂ{CCÂ(PPh<sub>3</sub>)ÂCH<sub>2</sub>CÂ(PPh<sub>3</sub>)ÂCH}Â(C<sub>9</sub>H<sub>6</sub>NO)Â(PPh<sub>3</sub>)]Cl (<b>2</b>), which
was fully characterized. Under an oxygen atmosphere, complex <b>2</b> can easily convert to complex <b>1</b>. DFT calculations
were carried out to rationalize the high regioselectivity in the reaction
of the ruthenabenene <b>1</b> with NaBH<sub>4</sub> and the
interconversion between <b>1</b> and <b>2</b>
Pulse-Reverse Electrodeposition and Micromachining of Graphene–Nickel Composite: An Efficient Strategy toward High-Performance Microsystem Application
Graphene
reinforced nickel (Ni) is an intriguing nanocomposite with tremendous
potential for microelectromechanical system (MEMS) applications by
remedying mechanical drawbacks of the metal matrix for device optimization,
though very few related works have been reported. In this paper, we
developed a pulse-reverse electrodeposition method for synthesizing
graphene–Ni (G–Ni) composite microcomponents with high
content and homogeneously dispersed graphene filler. While the Vickers
hardness is largely enhanced by 2.7-fold after adding graphene, the
Young’s modulus of composite under dynamic condition shows
∼1.4-fold increase based on the raised resonant frequency of
a composite microcantilever array. For the first time, we also demonstrate
the application of G–Ni composite in microsystems by fabricating
a Si micromirror with the composite supporting beams as well as investigate
the long-term stability of the mirror at resonant vibration. Compared
with the pure Ni counterpart, the composite mirror shows an apparently
lessened fluctuations of resonant frequency and scanning angle due
to a suppressed plastic deformation even under the sustaining periodic
loading. This can be ascribed to the reduced grain size of Ni matrix
and dislocation hindering in the presence of graphene by taking into
account the crystalline refinement strengthen mechanism. The rational
discussions also imply that the strong interface and efficient load
transfer between graphene layers and metal matrix play an important
role for improving stiffness in composite. It is believed that a proper
design of graphene–metal composite makes it a promising structural
material candidate for advanced micromechanical devices
Multidrug Resistance Protein 4 (MRP4/ABCC4) Protects Cells from the Toxic Effects of Halobenzoquinones
Halobenzoquinones (HBQs) are frequently
detected disinfection byproducts
(DBPs) in treated water. Recent studies have demonstrated that HBQs
are highly cytotoxic and capable of inducing the generation of reactive
oxygen species (ROS) and depleting cellular glutathione (GSH). Multidrug
resistance proteins (MRPs/ABCCs) are known to play a critical role
in the elimination of numerous drugs, carcinogens, toxicants, and
their conjugated metabolites. In general, little is known about the
roles of transporters in DBP toxicity. Here, we hypothesize that MRPs
may play roles in the detoxication of HBQs. To test this hypothesis,
we used human embryonic kidney 293 (HEK293) cells stably expressing
MRPs (MRP1, 3, 4, and 5) and HEK293 cells with empty vector (HEK-V)
to examine the comparative cytotoxicity of four HBQs: 2,6-dichloro-1,4-benzoquinone
(2,6-DCBQ), 2,6-dibromo-1,4-benzoquinone (2,6-DBBQ), 2,6-dichloro-3-methyl-1,4-benzoquinone
(DCMBQ), and 2,3,6-trichloro-1,4-benzoquinone (TriCBQ). The cytotoxicity
(IC<sub>50</sub>) of the four HBQs in HEK-MRP1, -MRP3, -MRP4, and
-MRP5 cells and the control HEK-V cells clearly showed that MRP4 had
the most significant effect on reducing the toxicity of the four HBQs.
To further support MRP4-mediated detoxication of HBQs, we examined
the HBQ-induced ROS levels in HEK-MRP4 and HEK-V cells. ROS levels
were significantly reduced in HEK-MRP4 cells compared with HEK-V cells
after HBQ treatment. Furthermore, it was found that MRP4-mediated
detoxication of the HBQs was GSH dependent, as the cytotoxicity of
the HBQs was increased in GSH-depleted HEK-MRP4 cells in comparison
to HEK-MRP4 cells. The GSH-dependent protection of cells from HBQs
supports the possibility of HBQ–GSH conjugate efflux by MRP4.
This study demonstrates a role for MRP4 in cellular protection against
HBQ DBP-induced toxicity and oxidative stress
Quantum Dots Based Mesoporous Structured Imprinting Microspheres for the Sensitive Fluorescent Detection of Phycocyanin
Phycocyanin
with important physiological/environmental significance has attracted
increasing attention; versatile molecularly imprinted polymers (MIPs)
have been applied to diverse species, but protein imprinting is still
quite difficult. Herein, using phycocyanin as template via a sol–gel
process, we developed a novel fluorescent probe for specific recognition
and sensitive detection of phycocyanin by quantum dots (QDs) based
mesoporous structured imprinting microspheres (SiO<sub>2</sub>@QDs@ms-MIPs),
obeying electron-transfer-induced fluorescence quenching mechanism.
When phycocyanin was present, a Meisenheimer complex would be produced
between phycocyanin and primary amino groups of QDs surface, and then
the photoluminescent energy of QDs would be transferred to the complex,
leading to the fluorescence quenching of QDs. As a result, the fluorescent
intensity of the SiO<sub>2</sub>@QDs@ms-MIPs was significantly decreased
within 8 min, and accordingly a favorable linearity within 0.02–0.8
μM and a high detectability of 5.9 nM were presented. Excellent
recognition specificity for phycocyanin over its analogues was displayed,
with a high imprinting factor of 4.72. Furthermore, the validated
probe strategy was successfully applied to seawater and lake water
sample analysis, and high recoveries in the range of 94.0–105.0%
were attained at three spiking levels of phycocyanin, with precisions
below 5.3%. The study provided promising perspectives to develop fluorescent
probes for convenient, rapid recognition and sensitive detection of
trace proteins from complex matrices, and further pushed forward protein
imprinting research
Eigenvector centrality coefficients of individuals based on HWI and DAI.
<p>Individuals of the same sex are presented from left to right (males for the first four and females for the next eight) in the descending order in hierarchy.</p
RvD1 inhibited phosphorylation of JNK and the Smad3 linker region but not Smad3 c-terminal phosphorylation in the obstructed kidney.
<p>Mice underwent sham or unilateral ureteral obstruction (UUO) surgery. Two days after UUO surgery, mice received intraperitoneal injections of RvD1 for another two days and were killed on day 4. (A) Immunoprecipitation (IP) of Smad3 followed by Western Blotting (WB) identified phosphorylation of the Smad3 C-terminal domain (p-C-Smad3) and linker region (p-T179 and p-S208) following unilateral ureteric obstruction (UUO) compared to the sham operated control. In addition, Smad3 IP pulled down phosphorylated JNK (p-JNK). (B) Western blot identifying phosphorylation of the Smad2 C-terminal domain (p-C-Smad2), total Smad2, total Smad4 and GAPDH. (C) Quantification of the relative levels of abundance of p-JNK, p-T179, p-S208, p-C-Smad3 compared to total Smad3, p-C-Smad2 compared to total Smad2 and total Smad4 compared to GAPDH. Data are mean ±SD from groups of 6 mice and analysis by one-way ANOVA with post hoc analysis with Tukey's multiple comparison test. *** <i>p</i><0.001; N.S., not significant.</p
Origin of Adamantanes and Diamantanes in Marine Source Rock
Thermal maturation-related variations
in the yields of lower diamondoids
(adamantanes and diamantanes) in source rock were investigated by
thermal simulation experiments based on a marine shale and kerogens
obtained from the shale via isolation and artificial maturation, representing
different maturity stages of the oil generation window. The simulations
show that lower diamondoids are formed and destroyed during thermal
maturation of the shale. For example, adamantanes are generated mainly
in the maturity range of 0.8%–1.8% EasyRo, then they begin
to degrade at 1.8% EasyRo. Diamantanes are produced mainly during
the maturity range of 1.0%–2.2% EasyRo and begin to degrade
at 2.2% EasyRo. The mineral matrix of shale may have a strong effect
on the destruction of diamondoids, leading to a reduction in the peak
yield and a reduction in the maturity level corresponding to the peak
yield of diamondoids. A comparison of the diamondoid yields from four
kerogens at different maturity levels indicates that the lower diamondoids
are derived mainly from secondary cracking of extractable organic
matter (bitumens) occurring in the source rock. For instance, at the
peak stage of adamantane formation (2.1% EasyRo), 75.6% of the total
adamantanes is generated from the cracking of bitumens and the remaining
24.4% is from the primary cracking of kerogens. Similarly, the yield
of diamantanes generated from the secondary cracking of bitumens accounts
for 87.8% of the total diamantanes at the peak stage of diamantane
formation (2.5% EasyRo). Almost no diamondoids are detected in the
pyrolysates of more mature kerogen (1.3%EasyRo), suggesting that 1.3%
EasyRo is the upper limit of maturity for the generation of diamondoids
from kerogen. Diamondoid isomerization ratios are maintained at relatively
constant levels during the formation stage of diamondoids, whereas
a linear correlation with maturity occurs during the destruction stage,
suggesting that isomerization ratios of diamondoids are controlled
by their thermal stability just in the destruction stage and are unaffected
by hydrocarbon generation and expulsion of source rock at early thermal
stages. This finding indicates that these diamondoid indices are a
potential tool for evaluating the thermal maturity of source rocks
at highly mature stages
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