3 research outputs found
Tandem S<sub>N</sub>2 Nucleophilic Substitution/Phospho-Dieckmann Reaction: One-Step Synthesis of 2āPhosphonyl-3-hydroxybenzo[<i>b</i>]thiophenes
A novel and efficient tandem SN2 nucleophilic
substitution/Dieckmann
condensation reaction of Ī±-iodomethyl phosphine oxide with methyl
thiosalicylate derivatives has been developed by using NaOH as a base,
which enables the expeditious synthesis of 2-phosphonyl-3-hydroxybenzo[b]thiophene derivatives in moderate to high yields under
simple conditions. This research provides not only a convenient method
for the functionalization of benzo[b]thiophenes at
the 2-position and 3-position but also new organophosphorus molecules.
Furthermore, several new phosphonyl-substituted benzo[b]thiophenes were obtained from the resultant 2-phosphonyl-3-hydroxybenzo[b]thiophenes
Divergent Carry-Over Effects of Hypoxia during the Early Development of Abalone
After being exposed to environmental stimuli during early
developmental
stages, some organisms may gain or weaken physiological regulating
abilities, which would have long-lasting effects on their performance.
Environmental hypoxia events can have significant effects on marine
organisms, but for breeding programs and other practical applications,
it is important to further explore the long-term physiological effects
of early hypoxia exposure in economically significant species. In
this study, the Pacific abalone Haliotis discus hannai was exposed to moderate hypoxia (ā¼4 mg/L) from zygote to
trochophora, and the assessments of hypoxia tolerance were conducted
on the grow-out stage. The results revealed that juvenile abalones
exposed to hypoxia at the early development stages were more hypoxia-tolerant
but with slower weight growth, a phenomenon called the trade-off between
growth and survival. These phenotypic effects driven by the hypoxia
exposure were explained by strong selection of genes involved in signal
transduction, autophagy, apoptosis, and hormone regulation. Moreover,
long non-coding RNA regulation plays an important role modulating
carry-over effects by controlling DNA replication and repair, signal
transduction, myocardial activity, and hormone regulation. This study
revealed that the ability to create favorable phenotypic differentiation
through genetic selection and/or epigenetic regulation is important
for the survival and development of aquatic animals in the face of
rapidly changing environmental conditions
Hierarchically Structured Thermoelectric Materials in Quaternary System CuāZnāSnāS Featuring a Mosaic-type Nanostructure
Multinary
chalcogenide semiconductors in the CuāZnāSnāS
system have numerous potential applications in the fields of energy
production, photocatalysis and nonlinear optics, but characterization
and control of their microstructures remains a challenge because of
the complexity resulting from the many mutually soluble metallic elements.
Here, using state-of-the-art scanning transmission electron microscopy,
energy dispersive spectroscopy, first-principles calculations and
classical molecular dynamics simulations, we characterize the structures
of promising thermoelectric materials Cu<sub>2</sub>(Zn,Sn)ĀS<sub>3</sub> at different length scales to gain a better understanding of how
the various components influence the thermoelectric behavior. We report
the discovery of a mosaic-type domain nanostructure in the matrix
grains comprising well-defined cation-disordered domains (the ātesseraeā)
coherently bonded to a surrounding network phase with semiordered
cations. The network phase is found to have composition Cu<sub>4+<i>x</i></sub>Zn<sub><i>x</i></sub>Sn<sub>2</sub>S<sub>7</sub>, a previously unknown phase in the CuāZnāSnāS
system, while the tesserae have compositions closer to that of the
nominal composition. This nanostructure represents a new kind of phonon-glass
electron-crystal, the cation-disordered tesserae and the abrupt domain
walls damping the thermal conductivity while the cation-(semi)Āordered
network phase supports a high electronic conductivity. Optimization
of the hierarchical architecture of these materials represents a new
strategy for designing environmentally benign, low-cost thermoelectrics
with high figures of merit