36 research outputs found
Role of the annealing parameters on the resistance of indium tin oxide nanocrystalline films
The optical and electrical properties of films made of nanoparticles of
indium tin oxide (ITO) are widely studied because of the significance of this
material for transparent electrodes, smart windows, and nonlinear optics
components. In this work, a systematic study of the resistance in ITO
nanocrystalline films, as a function of post fabrication parameters, such as
the temperature and time of annealing, has been performed. A tunability of the
resistance with the annealing parameters, in a range of three orders of
magnitude, has been demonstrated.Comment: 8 pages, 4 figure
Effective medium optical modelling of indium tin oxide nanocrystal films
: Doped semiconductor nanocrystal-based thin films are widely used for many applications, such as screens, electrochromic windows, light emitting diodes, and solar cells. Herein, we have employed spectroscopic ellipsometry to measure and model the complex dielectric response of indium tin oxide films fabricated by nanocrystal deposition and sintering. The films could be modelled as Bruggemann effective media, allowing estimation of the nanoscale interstitial porosity of the structure. The effective dielectric constants show the possibility of tuning the plasma frequency and the epsilon-near zero condition of the film
Electrochromism in Electrolyte-Free and Solution Processed Bragg Stacks
Achieving an active manipulation of colours has huge implications in
optoelectronics, as colours engineering can be exploited in a number of
applications, ranging from display to lightning. In the last decade, the
synergy of the highly pure colours of 1D photonic crystals, also known as Bragg
stacks, with electro-tunable materials have been proposed as an interesting
route to attain such a technologically relevant effect. However, recent works
rely on the use of liquid electrolytes, which can pose issues in terms of
chemical and environmental stability. Here, we report on the proof-of-concept
of an electrolyte free and solution-processed electrochromic Bragg stack. We
integrate an electro-responsive plasmonic metal oxide, namely indium tin oxide,
in a 1D photonic crystal structure made of alternating layers of ITO and TiO2
nanoparticles. In such a device we observed 15 nm blue-shift upon application
of an external bias (5 V), an effect that we attribute to the increase of ITO
charge density arising from the capacitive charging at the metal
oxide/dielectric interface and from the current flowing throughout the porous
structure. Our data suggest that electrochromism can be attained in all-solid
state systems by combining a judicious selection of the constituent materials
with device architecture optimisation
Optical Properties and Ultrafast Near‐Infrared Localized Surface Plasmon Dynamics in Naturally p‐Type Digenite Films
Copper chalcogenides are materials characterized by intrinsic doping properties, allowing them to display high carrier concentrations due to their defect-heavy structures, independent of the preparation method. Such high doping enables these materials to display plasmonic resonances, tunable by varying their stoichiometry, as shown previously for Cu2-xS, Cu2-xSe, and Cu2-xTe, with 0 1 ns) signal associated with phonon-phonon scattering relaxation. These results confirm the possibility of fabricating Cu9S5 films retaining the plasmonic properties of individual NCs, anticipating integrating these films into heterojunctions with suitable hole acceptor materials to build hot-hole-transfer-based optoelectronic devices
Near-Infrared Plasmon-Induced Hot Electron Extraction Evidence in an Indium Tin Oxide Nanoparticle/Monolayer Molybdenum Disulfide Heterostructure
: In this work, we observe plasmon-induced hot electron extraction in a heterojunction between indium tin oxide nanocrystals and monolayer molybdenum disulfide. We study the sample with ultrafast differential transmission, exciting the sample at 1750 nm where the intense localized plasmon surface resonance of the indium tin oxide nanocrystals is and where the monolayer molybdenum disulfide does not absorb light. With the excitation at 1750 nm, we observe the excitonic features of molybdenum disulfide in the visible range, close to the exciton of molybdenum disulfide. Such a phenomenon can be ascribed to a charge transfer between indium tin oxide nanocrystals and monolayer molybdenum disulfide upon plasmon excitation. These results are a first step toward the implementation of near-infrared plasmonic materials for photoconversion
Near-Infrared plasmon induced hot electron extraction evidence in an indium tin oxide nanoparticle / monolayer molybdenum disulphide heterostructure
In this work, we observe plasmon induced hot electron extraction in a
heterojunction between indium tin oxide nanocrystals and monolayer molybdenum
disulphide. We study the sample with ultrafast differential transmission
exciting the sample at 1750 nm where the intense localized plasmon surface
resonance of the indium tin oxide nanocrystals is and where the monolayer
molybdenum disulphide does not absorb light. With the excitation at 1750 nm we
observe the excitonic features of molybdenum disulphide in the visible range,
close to the exciton of molybdenum disulphide. Such phenomenon can be ascribed
to a charge transfer between indium tin oxide nanocrystals and monolayer
molybdenum disulphide upon plasmon excitation. These results are a first step
towards the implementation of near infrared plasmonic materials for
photoconversion.Comment: 12 pages, 3 figure
Tamm Plasmon Resonance as Optical Fingerprint of Silver/Bacteria Interaction
Incorporation of responsive elements into photonic crystals is an effective
strategy for building up active optical components to be used as sensors,
actuators and modulators. In these regards, Tamm Plasmon (TP) modes have arisen
recently as powerful optical tools for the manipulation of light-matter
interaction and for building sensors/actuators. These emerge at the interface
between a dielectric mirror and a plasmonic layer and, interestingly, can be
excited at normal incidence angle with relatively high quality factors.
Although its field is located at the interface between the dielectric mirror
and the metal, recent studies have demonstrated that corrugation at the
nanoscale permits to access the TP mode from the outside, opening new exciting
perspectives for many real-life applications. Here, we show that the TP
resonance obtained by capping a distributed Bragg reflector with a
nanostructured layer of silver is sensitive to the presence of bacteria. We
observed that nanoscale corrugation is essential for accessing the TP field,
while the well-known bio-responsivity of silver nanostructures renders such a
localised mode sensible to the presence of Escherichia Coli. Electrodoping
experiments confirm the pivotal role of nanostructuration, as well as
strengthening our hypothesis that the modifications of the TP mode upon
exposure to bacteria are related to the accumulation of negative charge due to
the bacterial-driven removal of Ag+ ions from its lattice. Finally, we devised
a case study in which we disentangled optically the presence of proliferative
and non-proliferative bacteria using the TP resonance as a read-out, thus
making these devices as promising simple all-optical probes for bacterial
metabolic activity, including their response against drugs and antibiotics
How future surgery will benefit from SARS-COV-2-related measures: a SPIGC survey conveying the perspective of Italian surgeons
COVID-19 negatively affected surgical activity, but the potential benefits resulting from adopted measures remain unclear. The aim of this study was to evaluate the change in surgical activity and potential benefit from COVID-19 measures in perspective of Italian surgeons on behalf of SPIGC. A nationwide online survey on surgical practice before, during, and after COVID-19 pandemic was conducted in March-April 2022 (NCT:05323851). Effects of COVID-19 hospital-related measures on surgical patients' management and personal professional development across surgical specialties were explored. Data on demographics, pre-operative/peri-operative/post-operative management, and professional development were collected. Outcomes were matched with the corresponding volume. Four hundred and seventy-three respondents were included in final analysis across 14 surgical specialties. Since SARS-CoV-2 pandemic, application of telematic consultations (4.1% vs. 21.6%; p < 0.0001) and diagnostic evaluations (16.4% vs. 42.2%; p < 0.0001) increased. Elective surgical activities significantly reduced and surgeons opted more frequently for conservative management with a possible indication for elective (26.3% vs. 35.7%; p < 0.0001) or urgent (20.4% vs. 38.5%; p < 0.0001) surgery. All new COVID-related measures are perceived to be maintained in the future. Surgeons' personal education online increased from 12.6% (pre-COVID) to 86.6% (post-COVID; p < 0.0001). Online educational activities are considered a beneficial effect from COVID pandemic (56.4%). COVID-19 had a great impact on surgical specialties, with significant reduction of operation volume. However, some forced changes turned out to be benefits. Isolation measures pushed the use of telemedicine and telemetric devices for outpatient practice and favored communication for educational purposes and surgeon-patient/family communication. From the Italian surgeons' perspective, COVID-related measures will continue to influence future surgical clinical practice
Association of Variants in the SPTLC1 Gene With Juvenile Amyotrophic Lateral Sclerosis
Importance: Juvenile amyotrophic lateral sclerosis (ALS) is a rare form of ALS characterized by age of symptom onset less than 25 years and a variable presentation.Objective: To identify the genetic variants associated with juvenile ALS.Design, Setting, and Participants: In this multicenter family-based genetic study, trio whole-exome sequencing was performed to identify the disease-associated gene in a case series of unrelated patients diagnosed with juvenile ALS and severe growth retardation. The patients and their family members were enrolled at academic hospitals and a government research facility between March 1, 2016, and March 13, 2020, and were observed until October 1, 2020. Whole-exome sequencing was also performed in a series of patients with juvenile ALS. A total of 66 patients with juvenile ALS and 6258 adult patients with ALS participated in the study. Patients were selected for the study based on their diagnosis, and all eligible participants were enrolled in the study. None of the participants had a family history of neurological disorders, suggesting de novo variants as the underlying genetic mechanism.Main Outcomes and Measures: De novo variants present only in the index case and not in unaffected family members.Results: Trio whole-exome sequencing was performed in 3 patients diagnosed with juvenile ALS and their parents. An additional 63 patients with juvenile ALS and 6258 adult patients with ALS were subsequently screened for variants in the SPTLC1 gene. De novo variants in SPTLC1 (p.Ala20Ser in 2 patients and p.Ser331Tyr in 1 patient) were identified in 3 unrelated patients diagnosed with juvenile ALS and failure to thrive. A fourth variant (p.Leu39del) was identified in a patient with juvenile ALS where parental DNA was unavailable. Variants in this gene have been previously shown to be associated with autosomal-dominant hereditary sensory autonomic neuropathy, type 1A, by disrupting an essential enzyme complex in the sphingolipid synthesis pathway.Conclusions and Relevance: These data broaden the phenotype associated with SPTLC1 and suggest that patients presenting with juvenile ALS should be screened for variants in this gene.</p
Genome-wide Analyses Identify KIF5A as a Novel ALS Gene
To identify novel genes associated with ALS, we undertook two lines of investigation. We carried out a genome-wide association study comparing 20,806 ALS cases and 59,804 controls. Independently, we performed a rare variant burden analysis comparing 1,138 index familial ALS cases and 19,494 controls. Through both approaches, we identified kinesin family member 5A (KIF5A) as a novel gene associated with ALS. Interestingly, mutations predominantly in the N-terminal motor domain of KIF5A are causative for two neurodegenerative diseases: hereditary spastic paraplegia (SPG10) and Charcot-Marie-Tooth type 2 (CMT2). In contrast, ALS-associated mutations are primarily located at the C-terminal cargo-binding tail domain and patients harboring loss-of-function mutations displayed an extended survival relative to typical ALS cases. Taken together, these results broaden the phenotype spectrum resulting from mutations in KIF5A and strengthen the role of cytoskeletal defects in the pathogenesis of ALS.Peer reviewe