937 research outputs found
Sodium hydroxide pretreatment as an effective approach to reduce the dye/holes recombination reaction in P-Type DSCs
We report the synthesis of a novel squaraine dye (VG21-C12) and investigate its behavior
as p-type sensitizer for p-type Dye-Sensitized Solar Cells. The results are compared
with O4-C12, a well-known sensitizer for p-DSC, and sodium hydroxide pretreatment
is described as an effective approach to reduce the dye/holes recombination. Various
variable investigation such as dipping time, dye loading, photocurrent, and resulting cell
efficiency are also reported. Electrochemical impedance spectroscopy (EIS) was utilized
for investigating charge transport properties of the different photoelectrodes and the
recombination phenomena that occur at the (un)modified electrode/electrolyte interface
Hypersensitive tunable Josephson escape sensor for gigahertz astronomy
Sensitive photon detection in the gigahertz band constitutes the cornerstone
to study different phenomena in astronomy, such as radio burst sources, galaxy
formation, cosmic microwave background, axions, comets, gigahertz-peaked
spectrum radio sources and supermassive black holes. Nowadays, state of the art
detectors for astrophysics are mainly based on transition edge sensors and
kinetic inductance detectors. Overall, most sensible nanobolometers so far are
superconducting detectors showing a noise equivalent power (NEP) as low as
2x10-20 W/Hz1/2. Yet, fast thermometry at the nanoscale was demonstrated as
well with Josephson junctions through switching current measurements. In
general, detection performance are set by the fabrication process and limited
by used materials. Here, we conceive and demonstrate an innovative tunable
Josephson escape sensor (JES) based on the precise current control of the
temperature dependence of a fully superconducting one-dimensional nanowire
Josephson junction. The JES might be at the core of future hypersensitive in
situ-tunable bolometers or single-photon detectors working in the gigahertz
regime. Operated as a bolometer the JES points to a thermal fluctuation noise
(TFN) NEP_TFN 1x10-25 W/Hz1/2, which as a calorimeter bounds the frequency
resolution above 2 GHz, and resolving power below 40 at 50 GHz, as deduced from
the experimental data. Beyond the obvious applications in advanced ground-based
and space telescopes for gigahertz astronomy, the JES might represent a
breakthrough in several fields of quantum technologies ranging from subTHz
communications and quantum computing to cryptography and quantum key
distribution.Comment: 14 pages, 8 figure
MICROWAVE-ASSISTED BRUCITE AND TALC REACTIONS WITH CO2 AS A PROXY FOR CARBON CAPTURE AND STORAGE BY SERPENTINE
In the last decades many studies have been focusing on Carbon Capture and Storage
(CCS) to find a possible remedy to reduce the large increase of anthropogenic carbon
dioxide (CO ). Mineral Carbonation (MC) is a potential solution for almost irreversible
chemical long-term CCS. It concerns the combination of CaO and MgO with CO forming
spontaneously and exothermically dolomite and magnesite. However, kinetic barriers
pose sever limitations for the practical exploitation of this reaction.
High fractions of MgO are available in silicates such as olivine, orthopyroxene,
clinopyroxene and serpentine. To date, data reported that serpentine polymorphs, above
all antigorite, is an excellent candidate for fixing the CO as the reaction efficiency is
approximately 92% compared to lizardite (40%) and olivine (66%). This is due to the
surface reactivity of approximately 18.7 m /g for the dehydrated antigorite compared
to10.8 m /g for dehydrated lizardite and 4.6 m /g for olivine.
The microwave assisted process for CCS is an innovative technology that can be
employed to catalyze the reaction through thermal and non-thermal mechanisms. Some
pioneering tests of direct carbonation by microwave hydrothermal equipment have been
performed on olivine, lizardite and chrysotile powders [1] but not on antigorite. The
structure of serpentine is characterized by corrugated stacked layers of silica and brucite.
For this reason, MC involves dissolution of SiO layers, dissolution/dehydration of
Mg(OH) layers, and precipitation of magnesium carbonate.
To address the chemical response of the single phases, experiments have been
performed by both a local microwave-source acting locally on a specific crystal surface
and a volume source interacting with an ensemble of grains on synthetic powders and
single crystals of pure brucite and talc. In a second step, treatments have been extended
to chrysotile, lizardite and antigorite. A characterization of the mechanism and kinetics
were performed by scanning probe microscopy on the surface of single crystals phases,
supported by Raman spectroscopy and by Scanning and Transmission Electron
Microscopy study performed on micro- and nano-sized grains.
[1] White, et al. Reaction mechanisms of magnesium silicates with carbon dioxide in
microwave fields. Final Report to the U.S. Department ofEnergy, National Energy
Technology Laboratory (2004
Development of highly sensitive nanoscale transition edge sensors for gigahertz astronomy and dark matter search
Terahertz and sub-terahertz band detection has a key role both in fundamental
interactions physics and technological applications, such as medical imaging,
industrial quality control and homeland security. In particular, transition
edge sensors (TESs) and kinetic inductance detectors (KIDs) are the most
employed bolometers and calorimeters in the THz and sub-THz band for
astrophysics and astroparticles research. Here, we present the electronic,
thermal and spectral characterization of an aluminum/copper bilayer sensing
structure that, thanks to its thermal properties and a simple miniaturized
design, could be considered a perfect candidate to realize an extremely
sensitive class of nanoscale TES (nano-TES) for the giga-therahertz band.
Indeed, thanks to the reduced dimensionality of the active region and the
efficient Andreev mirror (AM) heat confinement, our devices are predicted to
reach state-of-the-art TES performance. In particular, as a bolometer the
nano-TES is expected to have a noise equivalent power (NEP) of
W/ and a relaxation time of ns
for the sub-THz band, typical of cosmic microwave background studies. When
operated as single-photon sensor, the devices are expected to show a remarkable
frequency resolution of 100 GHz, pointing towards the necessary energy
sensitivity requested in laboratory axion search experiments. Finally,
different multiplexing schemes are proposed and sized for imaging applications.Comment: 12 page, 7 figure
Phylogeography and population genetic structure of the European roe deer in Switzerland following recent recolonization
In the early 1800s, the European roe deer (Capreolus capreolus) was probably extirpated from Switzerland, due to overhunting and deforestation. After a federal law was enacted in 1875 to protect lactating females and young, and limiting the hunting season, the roe deer successfully recovered and recolonized Switzerland. In this study, we use mitochondrial DNA and nuclear DNA markers to investigate the recolonization and assess contemporary genetic structure in relation to broad topographic features, in order to understand underlying ecological processes, inform future roe deer management strategies, and explore the opportunity for development of forensic traceability tools. The results concerning the recolonization origin support natural, multidirectional immigration from neighboring countries. We further demonstrate that there is evidence of weak genetic differentiation within Switzerland among topographic regions. Finally, we conclude that the genetic data support the recognition of a single roe deer management unit within Switzerland, within which there is a potential for broadâscale geographic origin assignment using nuclear markers to support law enforcement
Citron Kinase Deficiency Leads to Chromosomal Instability and TP53-Sensitive Microcephaly
Mutations in citron (CIT), leading to loss or inactivation of the citron kinase protein (CITK), cause primary microcephaly in humans and rodents, associated with cytokinesis failure and apoptosis in neural progenitors. We show that CITK loss induces DNA damage accumulation and chromosomal instability in both mammals and Drosophila. CITK-deficient cells display "spontaneous" DNA damage, increased sensitivity to ionizing radiation, and defective recovery from radiation-induced DNA lesions. In CITK-deficient cells, DNA double-strand breaks increase independently of cytokinesis failure. Recruitment of RAD51 to DNA damage foci is compromised by CITK loss, and CITK physically interacts with RAD51, suggesting an involvement of CITK in homologous recombination. Consistent with this scenario, in doubly CitK and Trp53 mutant mice, neural progenitor cell death is dramatically reduced; moreover, clinical and neuroanatomical phenotypes are remarkably improved. Our results underscore a crucial role of CIT in the maintenance of genomic integrity during brain development
Phylogeography and population genetic structure of the European roe deer in Switzerland following recent recolonization
n the early 1800s, the European roe deer (Capreolus capreolus) was probably extirpated from Switzerland, due to overhunting and deforestation. After a federal law was en-acted in 1875 to protect lactating females and young, and limiting the hunting season, the roe deer successfully recovered and recolonized Switzerland. In this study, we use mitochondrial DNA and nuclear DNA markers to investigate the recolonization and as-sess contemporary genetic structure in relation to broad topographic features, in order to understand underlying ecological processes, inform future roe deer management strategies, and explore the opportunity for development of forensic traceability tools. The results concerning the recolonization origin support natural, multidirectional immi-gration from neighboring countries. We further demonstrate that there is evidence of weak genetic differentiation within Switzerland among topographic regions. Finally, we conclude that the genetic data support the recognition of a single roe deer management unit within Switzerland, within which there is a potential for broad- scale geographic origin assignment using nuclear markers to support law enforcement
Hyper-activation of the Rho-GTPase Rac1 via disruption of ArhGAP15 results in reduced architectural and functional complexity
Regional spread of an atypical ESBL-producing Escherichia coli ST131H89 clone among different human and environmental reservoirs in Western Switzerland
We describe the inter-regional spread of a novel ESBL-producing Escherichia coli subclone (ST131H89) in long-term care facility residents, general population, and environmental water sources in Western Switzerland between 2017 and 2020. The study highlights the importance of molecular surveillance for tracking emerging antibiotic-resistant pathogens in healthcare and community settings
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