191 research outputs found
A Simplified, Light Emitting Diode (LED) based, modular system to be used for the rapid evaluation of fruit and vegetable quality: development and validation on dye solutions
NIR spectroscopy has proven to be one of the most efficient and ready to transfer tools to monitor product's quality. Portable VIS/NIR instruments are particularly versatile and suitable for field use to monitor the ripening process or quality parameters. The aim of this work is to develop and evaluate a new simplified optoelectronic system for potential measurements on fruit and vegetables directly in the field. The development, characterization and validation of an operative prototype is discussed. LED technology was chosen for the design, and spectral acquisition at four specific wavelengths (630, 690, 750 and 850 nm) was proposed. Nevertheless, attention was given to the modularity and versatility of the system. Indeed, the possibility to change the light sources module with other wavelengths allows one to adapt the use of the same device for different foreseeable applications and objectives, e.g., ripeness evaluation, detection of particular diseases and disorders, chemical and physical property prediction, shelf life analysis, as well as for different natures of products (berry, leaf or liquid). Validation tests on blue dye water solutions have shown the capability of the system of discriminating low levels of reflectance, with a repeatability characterized by a standard deviation proportional to the measured intensity and in general limited to 2%-4%
A novel CCM1 mutation associated with multiple cerebral and vertebral cavernous malformations
Background: Cerebral cavernous malformations are relatively rare vascular disorders that may affect any part of the central nervous system. This presentation has been associated with heterozygous mutations in CCM1/KRIT1, CCM2/malcavernin and CCM3/PDCD10. We aimed to investigate the genetic defect underlying multiple cerebral and vertebral cavernous malformations in a multigenerational Italian family.Case presentation: The proband is a 49-year-old man who underwent cerebral MRI in his thirties for persistent haeadache and tingling in his left arm and leg and was diagnosed with multiple supratentorial cavernous angiomas. A right frontal angioma with radiological evidence of a recent bleeding was surgically removed when he was 39\ua0years old and he was thereafter asymptomatic. Magnetic resonance imaging revealed multiple cerebral cavernous malformations in seven members of his familily. Four subjects were asymptomatic. Other family mambers displayed heterogeneous clinical features including seizures and recurrent brain haemorrhages. Sequence analysis in the proband disclosed a novel heterozygous nucleotide substitution (c.263-10A > G) in intron 5 of CCM1. This variant is predicted to create an abnormal acceptor splice site and segregated in affected relatives available for molecular screening. The analysis of CCM1 transcript in proband's lymphocytes confirmed the partial retention of intron 3 resulting in a premature termination codon.Conclusions: Our findings demonstrate that c.263-10A > G mutation is associated with cerebral cavernous malformations. A better knowledge of the disease-associated phenotype may lead to an early diagnosis and to an appropriate clinical surveillance in affected patients
Universality of pseudogap and emergent order in lightly doped Mott insulators
It is widely believed that high-temperature superconductivity in the cuprates
emerges from doped Mott insulators. The physics of the parent state seems
deceivingly simple: The hopping of the electrons from site to site is
prohibited because their on-site Coulomb repulsion U is larger than the kinetic
energy gain t. When doping these materials by inserting a small percentage of
extra carriers, the electrons become mobile but the strong correlations from
the Mott state are thought to survive; inhomogeneous electronic order, a
mysterious pseudogap and, eventually, superconductivity appear. How the
insertion of dopant atoms drives this evolution is not known, nor whether these
phenomena are mere distractions specific to hole-doped cuprates or represent
the genuine physics of doped Mott insulators. Here, we visualize the evolution
of the electronic states of (Sr1-xLax)2IrO4, which is an effective spin-1/2
Mott insulator like the cuprates, but is chemically radically different. Using
spectroscopic-imaging STM, we find that for doping concentration of x=5%, an
inhomogeneous, phase separated state emerges, with the nucleation of pseudogap
puddles around clusters of dopant atoms. Within these puddles, we observe the
same glassy electronic order that is so iconic for the underdoped cuprates.
Further, we illuminate the genesis of this state using the unique possibility
to localize dopant atoms on topographs in these samples. At low doping, we find
evidence for much deeper trapping of carriers compared to the cuprates. This
leads to fully gapped spectra with the chemical potential at mid-gap, which
abruptly collapse at a threshold of around 4%. Our results clarify the melting
of the Mott state, and establish phase separation and electronic order as
generic features of doped Mott insulators.Comment: This version contains the supplementary information and small updates
on figures and tex
The 3-Band Hubbard-Model versus the 1-Band Model for the high-Tc Cuprates: Pairing Dynamics, Superconductivity and the Ground-State Phase Diagram
One central challenge in high- superconductivity (SC) is to derive a
detailed understanding for the specific role of the - and
- orbital degrees of freedom. In most theoretical studies an
effective one-band Hubbard (1BH) or t-J model has been used. Here, the physics
is that of doping into a Mott-insulator, whereas the actual high- cuprates
are doped charge-transfer insulators. To shed light on the related question,
where the material-dependent physics enters, we compare the competing magnetic
and superconducting phases in the ground state, the single- and two-particle
excitations and, in particular, the pairing interaction and its dynamics in the
three-band Hubbard (3BH) and 1BH-models. Using a cluster embedding scheme, i.e.
the variational cluster approach (VCA), we find which frequencies are relevant
for pairing in the two models as a function of interaction strength and doping:
in the 3BH-models the interaction in the low- to optimal-doping regime is
dominated by retarded pairing due to low-energy spin fluctuations with
surprisingly little influence of inter-band (p-d charge) fluctuations. On the
other hand, in the 1BH-model, in addition a part comes from "high-energy"
excited states (Hubbard band), which may be identified with a non-retarded
contribution. We find these differences between a charge-transfer and a Mott
insulator to be renormalized away for the ground-state phase diagram of the
3BH- and 1BH-models, which are in close overall agreement, i.e. are
"universal". On the other hand, we expect the differences - and thus, the
material dependence to show up in the "non-universal" finite-T phase diagram
(-values).Comment: 17 pages, 9 figure
From bench to bedside: in vitro and in vivo evaluation of a neonate-focused nebulized surfactant delivery strategy.
BACKGROUND:
Non-invasive delivery of nebulized surfactant has been a neonatology long-pursued goal. Nevertheless, the clinical efficacy of nebulized surfactant remains inconclusive, in part, due to the great technical challenges of depositing nebulized drugs in the lungs of preterm infants. The aim of this study was to investigate the feasibility of delivering nebulized surfactant (poractant alfa) in vitro and in vivo with an adapted, neonate-tailored aerosol delivery strategy.
METHODS:
Particle size distribution of undiluted poractant alfa aerosols generated by a customized eFlow-Neos nebulizer system was determined by laser diffraction. The theoretical nebulized surfactant lung dose was estimated in vitro in a clinical setting replica including a neonatal continuous positive airway pressure (CPAP) circuit, a cast of the upper airways of a preterm neonate, and a breath simulator programmed with the tidal breathing pattern of an infant with mild respiratory distress syndrome (RDS). A dose-response study with nebulized surfactant covering the 100-600\u2009mg/kg nominal dose-range was conducted in RDS-modelling, lung-lavaged spontaneously-breathing rabbits managed with nasal CPAP. The effects of nebulized poractant alfa on arterial gas exchange and lung mechanics were assessed. Exogenous alveolar disaturated-phosphatidylcholine (DSPC) in the lungs was measured as a proxy of surfactant deposition efficacy.
RESULTS:
Laser diffraction studies demonstrated suitable aerosol characteristics for inhalation (mass median diameter, MMD\u2009=\u20093\u2009\u3bcm). The mean surfactant lung dose determined in vitro was 13.7%\u2009\ub1\u20094.0 of the 200\u2009mg/kg nominal dose. Nebulized surfactant delivered to spontaneously-breathing rabbits during nasal CPAP significantly improved arterial oxygenation compared to animals receiving CPAP only. Particularly, the groups of animals treated with 200\u2009mg/kg and 400\u2009mg/kg of nebulized poractant alfa achieved an equivalent pulmonary response in terms of oxygenation and lung mechanics as the group of animals treated with instilled surfactant (200\u2009mg/kg).
CONCLUSIONS:
The customized eFlow-Neos vibrating-membrane nebulizer system efficiently generated respirable aerosols of undiluted poractant alfa. Nebulized surfactant delivered at doses of 200\u2009mg/kg and 400\u2009mg/kg elicited a pulmonary response equivalent to that observed after treatment with an intratracheal surfactant bolus of 200\u2009mg/kg. This bench-characterized nebulized surfactant delivery strategy is now under evaluation in Phase II clinical trial (EUDRACT No.:2016-004547-36)
From bench to bedside: In vitro and in vivo evaluation of a neonate-focused nebulized surfactant delivery strategy
Background: Non-invasive delivery of nebulized surfactant has been a neonatology long-pursued goal.
Nevertheless, the clinical efficacy of nebulized surfactant remains inconclusive, in part, due to the great technical
challenges of depositing nebulized drugs in the lungs of preterm infants. The aim of this study was to investigate
the feasibility of delivering nebulized surfactant (poractant alfa) in vitro and in vivo with an adapted, neonate-
tailored aerosol delivery strategy.
Methods: Particle size distribution of undiluted poractant alfa aerosols generated by a customized eFlow-Neos
nebulizer system was determined by laser diffraction. The theoretical nebulized surfactant lung dose was estimated
in vitro in a clinical setting replica including a neonatal continuous positive airway pressure (CPAP) circuit, a cast of
the upper airways of a preterm neonate, and a breath simulator programmed with the tidal breathing pattern of an
infant with mild respiratory distress syndrome (RDS). A dose-response study with nebulized surfactant covering the
100\u2013600 mg/kg nominal dose-range was conducted in RDS-modelling, lung-lavaged spontaneously-breathing
rabbits managed with nasal CPAP. The effects of nebulized poractant alfa on arterial gas exchange and lung
mechanics were assessed. Exogenous alveolar disaturated-phosphatidylcholine (DSPC) in the lungs was measured
as a proxy of surfactant deposition efficacy.
Results: Laser diffraction studies demonstrated suitable aerosol characteristics for inhalation (mass median
diameter, MMD = 3 \u3bcm). The mean surfactant lung dose determined in vitro was 13.7% \ub1 4.0 of the 200 mg/kg
nominal dose. Nebulized surfactant delivered to spontaneously-breathing rabbits during nasal CPAP significantly
improved arterial oxygenation compared to animals receiving CPAP only. Particularly, the groups of animals treated
with 200 mg/kg and 400 mg/kg of nebulized poractant alfa achieved an equivalent pulmonary response in terms of
oxygenation and lung mechanics as the group of animals treated with instilled surfactant (200 mg/kg).
Conclusions: The customized eFlow-Neos vibrating-membrane nebulizer system efficiently generated respirable
aerosols of undiluted poractant alfa. Nebulized surfactant delivered at doses of 200 mg/kg and 400 mg/kg elicited a
pulmonary response equivalent to that observed after treatment with an intratracheal surfactant bolus of 200 mg/kg.
This bench-characterized nebulized surfactant delivery strategy is now under evaluation in Phase II clinical trial
(EUDRACT No.:2016\u2013004547-36)
Strong electronic correlations in superconducting organic charge transfer salts
We review the role of strong electronic correlations in
quasi--two-dimensional organic charge transfer salts such as (BEDT-TTF),
(BETS) and -[Pd(dmit)]. We begin by defining minimal
models for these materials. It is necessary to identify two classes of
material: the first class is strongly dimerised and is described by a
half-filled Hubbard model; the second class is not strongly dimerised and is
described by a quarter filled extended Hubbard model. We argue that these
models capture the essential physics of these materials. We explore the phase
diagram of the half-filled quasi--two-dimensional organic charge transfer
salts, focusing on the metallic and superconducting phases. We review work
showing that the metallic phase, which has both Fermi liquid and `bad metal'
regimes, is described both quantitatively and qualitatively by dynamical mean
field theory (DMFT). The phenomenology of the superconducting state is still a
matter of contention. We critically review the experimental situation, focusing
on the key experimental results that may distinguish between rival theories of
superconductivity, particularly probes of the pairing symmetry and measurements
of the superfluid stiffness. We then discuss some strongly correlated theories
of superconductivity, in particular, the resonating valence bond (RVB) theory
of superconductivity. We conclude by discussing some of the major challenges
currently facing the field.Comment: A review: 52 pages; 10 fig
Electronic Structure Calculation by First Principles for Strongly Correlated Electron Systems
Recent trends of ab initio studies and progress in methodologies for
electronic structure calculations of strongly correlated electron systems are
discussed. The interest for developing efficient methods is motivated by recent
discoveries and characterizations of strongly correlated electron materials and
by requirements for understanding mechanisms of intriguing phenomena beyond a
single-particle picture. A three-stage scheme is developed as renormalized
multi-scale solvers (RMS) utilizing the hierarchical electronic structure in
the energy space. It provides us with an ab initio downfolding of the global
band structure into low-energy effective models followed by low-energy solvers
for the models. The RMS method is illustrated with examples of several
materials. In particular, we overview cases such as dynamics of semiconductors,
transition metals and its compounds including iron-based superconductors and
perovskite oxides, as well as organic conductors of kappa-ET type.Comment: 44 pages including 38 figures, to appear in J. Phys. Soc. Jpn. as an
invited review pape
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