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result(s) for
"Jung, D."
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MXene-based novel nanocomposites doped SnO2 for boosting the performance of perovskite solar cells
Since being first published in 2018, the use of two-dimensional MXene in solar cells has attracted significant interest. This study presents, for the first time, the synthesis of an efficient hybrid electrocatalyst in the form of a nanocomposite (MXene/CoS)-SnO
2
designed to function as a high-performance electron transfer layer (ETL). The study can be divided into three distinct parts. The first part involves the synthesis of single-layer Ti
3
C
2
T
x
MXene nanosheets, followed by the preparation of a CoS solution. Subsequently, in the second part, the fabrication of MXene/CoS heterostructure nanocomposites is carried out, and a comprehensive characterization is conducted to evaluate the physical, structural, and optical properties. In the third part, the attention is on the crucial characterizations of the novel nanocomposite-electron transport layer (ETL) solution, significantly contributing to the evolution of perovskite solar cells. Upon optimising the composition, an exceptional power conversion efficiency of more than 17.69% is attained from 13.81% of the control devices with fill factor (FF), short-circuit current density (J
sc
), and open-circuit voltage (V
oc
) were 66.51%, 20.74 mA/cm
2
, and 1.282 V. Therefore, this PCE is 21.93% higher than the control device. The groundbreaking MXene/CoS (2 mg mL
−1
) strategy reported in this research represents a promising and innovative avenue for the realization of highly efficient perovskite solar cells.
Journal Article
Affinity-matured homotypic interactions induce spectrum of PfCSP structures that influence protection from malaria infection
The generation of high-quality antibody responses to
Plasmodium falciparum
(Pf) circumsporozoite protein (PfCSP), the primary surface antigen of
Pf
sporozoites, is paramount to the development of an effective malaria vaccine. Here we present an in-depth structural and functional analysis of a panel of potent antibodies encoded by the immunoglobulin heavy chain variable (IGHV) gene
IGHV3-33
, which is among the most prevalent and potent antibody families induced in the anti-PfCSP immune response and targets the Asn-Ala-Asn-Pro (NANP) repeat region. Cryo-electron microscopy (cryo-EM) reveals a remarkable spectrum of helical antibody-PfCSP structures stabilized by homotypic interactions between tightly packed fragments antigen binding (Fabs), many of which correlate with somatic hypermutation. We demonstrate a key role of these mutated homotypic contacts for high avidity binding to PfCSP and in protection from Pf malaria infection. Together, these data emphasize the importance of anti-homotypic affinity maturation in the frequent selection of
IGHV3–33
antibodies and highlight key features underlying the potent protection of this antibody family.
Here, the authors use cryo-EM to solve the structures of seven potent human antibodies, and demonstrate in vivo protection in a liver burden assay, using chimeric
Plasmodium berghei
sporozoites expressing
Plasmodium falciparum
circumsporozoite protein.
Journal Article
Picosecond metrology of laser-driven proton bursts
Tracking primary radiation-induced processes in matter requires ultrafast sources and high precision timing. While compact laser-driven ion accelerators are seeding the development of novel high instantaneous flux applications, combining the ultrashort ion and laser pulse durations with their inherent synchronicity to trace the real-time evolution of initial damage events has yet to be realized. Here we report on the absolute measurement of proton bursts as short as 3.5±0.7 ps from laser solid target interactions for this purpose. Our results verify that laser-driven ion acceleration can deliver interaction times over a factor of hundred shorter than those of state-of-the-art accelerators optimized for high instantaneous flux. Furthermore, these observations draw ion interaction physics into the field of ultrafast science, opening the opportunity for quantitative comparison with both numerical modelling and the adjacent fields of ultrafast electron and photon interactions in matter.
Experimental investigations of the response of matter to ionization would require extremely fast ion pump pulses. Here, the authors explore a different approach observing ionisation dynamics in SiO
2
glass by generating synchronized proton pulses from the interaction of high-power lasers on a solid target.
Journal Article
Coherent synchrotron emission from electron nanobunches formed in relativistic laser–plasma interactions
Extreme ultraviolet and X-ray radiation can be generated when the high harmonics of incident laser light are reflected by a dense plasma, the so-called relativistically oscillating mirror mechanism. Theoretical studies have, however, predicted an alternative regime in which short-wavelength light is generated by dense electron nanobunches that form at the plasma–vacuum boundary. Signatures of this coherent synchrotron emission are now experimentally observed.
Extreme ultraviolet (XUV) and X-ray harmonic spectra produced by intense laser–solid interactions have, so far, been consistent with Doppler upshifted reflection from collective relativistic plasma oscillations—the relativistically oscillating mirror mechanism
1
,
2
,
3
,
4
,
5
,
6
. Recent theoretical work, however, has identified a new interaction regime in which dense electron nanobunches are formed at the plasma–vacuum boundary resulting in coherent XUV radiation by coherent synchrotron emission
7
,
8
(CSE). Our experiments enable the isolation of CSE from competing processes, demonstrating that electron nanobunch formation does indeed occur. We observe spectra with the characteristic spectral signature of CSE—a slow decay of intensity,
I
, with high-harmonic order,
n
, as
I
(
n
)
n
−1.62
before a rapid efficiency rollover. Particle-in-cell code simulations reveal how dense nanobunches of electrons are periodically formed and accelerated during normal-incidence interactions with ultrathin foils and result in CSE in the transmitted direction. This observation of CSE presents a route to high-energy XUV pulses
7
,
8
and offers a new window on understanding ultrafast energy coupling during intense laser–solid density interactions.
Journal Article
Size Matters More than Chemistry for Cloud-Nucleating Ability of Aerosol Particles
Size-resolved cloud condensation nuclei (CCN) spectra measured for various aerosol types at a non-urban site in Germany showed that CCN concentrations are mainly determined by the aerosol number size distribution. Distinct variations of CCN activation with particle chemical composition were observed but played a secondary role. When the temporal variation of chemical effects on CCN activation is neglected, variation in the size distribution alone explains 84 to 96% of the variation in CCN concentrations. Understanding that particles' ability to act as CCN is largely controlled by aerosol size rather than composition greatly facilitates the treatment of aerosol effects on cloud physics in regional and global models.
Journal Article
A review of soft errors and the low α-solder bumping process in 3-D packaging technology
This study reviews soft errors in modern electronic assemblies, through silicon via (TSV), and low α-solder bumping techniques for 3-D microelectronic packaging. The TSV fabrication involves deep reactive ion-etching process of Si wafers to form vertical holes, which are further filled with copper and joined to solder bumps. The solder bumps in close proximity to Si die thus impose a serious threat of soft errors. These soft errors responsible for the malfunction of electronic systems have become a critical issue in miniaturized and high-density packaging, like 3-D packaging. Various low α-solder bumping techniques have been reported to minimize these errors in modern microelectronic devices. A low α-solder is one that has low levels of α-particle emission, as compared to the conventional solder. In addition, it improves the performance and reliability of the solder joints, prompting the need to adopt low α-solder for bumping in TSV packaging. Thus, this paper discusses the various aspects of TSV fabrication, functional layer deposition, Cu filling into TSV, and low α-solder bumping on TSV by solder ball reflow methods.
Journal Article
Endoplasmic reticulum stress mediates radiation-induced autophagy by perk-eIF2α in caspase-3/7-deficient cells
As apoptosis defects limit efficacy of anticancer agents, autophagy has been proposed as a novel strategy for radiotherapy enhancement. We previously showed that caspase-3/7 inhibition induces autophagy and promotes radiosensitivity
in vitro
and
in viv
o. Therefore, we further investigated the mechanism by which radiation triggers autophagy in caspase-3/7-deficient cells, and found the involvement of endoplasmic reticulum (ER) stress. The ER activates a survival pathway, the unfolded protein response, which involves ER-localized transmembrane proteins such as protein kinase-like ER kinase (PERK), inositol-requiring enzyme-1 and activating transcription factor-6. In this study, we found that PERK is essential for radiation-induced autophagy and radiosensitivity in caspase-3/7 double-knockout cells. Irradiation of these cells increased expression of phosphorylated-eIF2α. Similar results were seen after administration of tunicamycin (TM), a well-known ER stressor. Importantly, we found that the administration of TM with radiation in MCF-7 breast cancer cells, which are lacking functional caspase-3 and relatively resistant to many anticancer agents, enhances radiation sensitivity. Our findings reveal ER stress as a novel potential mechanism of radiation-induced autophagy in caspase-3/7-deficient cells and as a potential strategy to maximize efficiency of radiation therapy in breast cancer.
Journal Article
Observation of reactor antineutrino disappearance using delayed neutron capture on hydrogen at RENO
A
bstract
The Reactor Experiment for Neutrino Oscillation (RENO) experiment has been taking data using two identical liquid scintillator detectors since August 2011. The experiment has observed the disappearance of reactor neutrinos in their interactions with free protons, followed by neutron capture on hydrogen (n-H). Based on 1500 live days of data taken with 16.8 GW
th
reactors at the Hanbit Nuclear Power Plant in Korea, the near (far) detector observes 567690 (90747) electron antineutrino candidate events with the n-H data. This provides an independent measurement of neutrino mixing angle
θ
13
and a consistency check on the validity of the result obtained from the data with neutron capture on Gadolinium (n-Gd). Furthermore, it provides an important cross-check on the systematic uncertainties of the n-Gd measurement. Based on a rate-only analysis, we obtain sin
2
2
θ
13
= 0
.
086 ± 0
.
008(stat
.
) ± 0
.
014(syst
.
). The combination of this result with that of n-Gd is also reported.
Journal Article
SVCT-2 in breast cancer acts as an indicator for L-ascorbate treatment
L
-ascorbate (
L
-ascorbic acid, vitamin C) clearly has an inhibitory effect on cancer cells. However, the mechanism underlying differential sensitivity of cancer cells from same tissue to
L
-ascorbate is yet to be clarified. Here, we demonstrate that
L
-ascorbate has a selective killing effect, which is influenced by sodium-dependent vitamin C transporter 2 (SVCT-2) in human breast cancer cells. Treatment of human breast cancer cells with
L
-ascorbate differentially induced cell death, dependent on the SVCT-2 protein level. Moreover, knockdown of endogenous SVCT-2 via RNA interference in breast cancer cells expressing high levels of the protein induced resistance to
L
-ascorbate treatment, whereas transfection with SVCT-2 expression plasmids led to enhanced
L
-ascorbate chemosensitivity. Surprisingly, tumor regression by
L
-ascorbate administration in mice bearing tumor cell xenograft also corresponded to the SVCT-2 protein level. Interestingly, SVCT-2 expression was absent or weak in normal tissues, but strongly detected in tumor samples obtained from breast cancer patients. In addition, enhanced chemosensitivity to
L
-ascorbate occurred as a result of caspase-independent autophagy, which was mediated by beclin-1 and LC3 II. In addition, treatment with N-acetyl-
L
-cysteine, a reactive oxygen species (ROS) scavenger, suppressed the induction of beclin-1 and LC3 II, implying that the differential SVCT-2 protein-dependent
L
-ascorbate uptake was attributable to intracellular ROS induced by
L
-ascorbate, subsequently leading to autophagy. These results suggest that functional SVCT-2 sensitizes breast cancer cells to autophagic damage by increasing the
L
-ascorbate concentration and intracellular ROS production and furthermore, SVCT-2 in breast cancer may act as an indicator for commencing
L
-ascorbate treatment.
Journal Article