The authors in this article explore the experiences of eight South Korean nurses during an outbreak of the Middle East Respiratory Syndrome (MERS), which took place in the fall of 2015. These nurses were mandated to remain in isolation in an intensive care unit (ICU) dedicated to the treatment of the patients with the MERS virus for 7 days. Parse's humanbecoming theory was used to frame the discussion. Three themes found in the nurse's stories are discussed: feeling hopeless and cut off, feeling shame and overworked, and feeling pride in fulfilling a duty. The nurses discuss how they overcame the difficulties of their situation, which ultimately reinforced their identities as nurses.
A series of asymmetric donor−acceptor (D−A) perylene-based compounds, 3-(N,N-bis(4′-(R)-phenyl)amino)perylene (Peri−DPA(R)), were successfully prepared to explore their intramolecular charge transfer (ICT) properties. To induce ICT between the donor and acceptor, diphenylamine (DPA) derivatives (electron donor units) with the same functional groups (R = CN, F, H, Me, or OMe) at both para positions were linked to the C-3 position of perylene to produce five Peri−DPA derivatives. A steady-state spectroscopy study on Peri−DPA(R)s exhibited a progressively regulated ICT trend consistent with the substituent effect as it progressed from the electron-withdrawing group to the electrondonating group. In particular, a comparative study using a D−A−D (donor−acceptor− donor) system demonstrated that not only the electron push−pull substituent effect but also subunit combinations influence photophysical and electrochemical properties. The different ICT characters observed in Lippert−Mataga plots of D−A(CN) and D−A−D(CN) (CNsubstituted D−A and D−A−D) led to the investigation on whether ICT emission of two systems with differences in subunit combinations is of the same type or of a different type. The femtosecond transient absorption (fs-TA) spectroscopic results provided direct evidence of ICT origin and confirmed that D− A(CN) and D−A−D(CN) exhibited the same transition mix of ICT (from donor to acceptor) and reverse ICT (rICT, from arylamine to CN unit). Density functional theory (DFT)/TD-DFT calculations support the presence of ICT for all five compounds, and the experimental observations of rICT presented only for CN-substituted compounds.
A 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.
Cold stress is known as the important yield-limiting factor of heading type Kimchi cabbage (HtKc, Brassica rapa L. ssp. pekinensis), which is an economically important crop worldwide. However, the biochemical and molecular responses to cold stress in HtKc are largely unknown. In this study, we conducted transcriptome analyses on HtKc grown under normal versus cold conditions to investigate the molecular mechanism underlying HtKc responses to cold stress. A total of 2131 genes (936 up-regulated and 1195 down-regulated) were identified as differentially expressed genes and were significantly annotated in the category of “response to stimulus.” In addition, cold stress caused the accumulation of polyphenolic compounds, including p-coumaric, ferulic, and sinapic acids, in HtKc by inducing the phenylpropanoid pathway. The results of the chemical-based antioxidant assay indicated that the cold-induced polyphenolic compounds improved the free-radical scavenging activity and antioxidant capacity, suggesting that the phenylpropanoid pathway induced by cold stress contributes to resistance to cold-induced reactive oxygen species in HtKc. Taken together, our results will serve as an important base to improve the cold tolerance in plants via enhancing the antioxidant machinery.
Charge transfer (CT) from electron donor (D) to acceptor (A) plays an important role in photoelectric or electrochemical devices and is a useful concept for a molecule with D and...
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