4,184 research outputs found
AIEgen orthopalladated hybrid polymers for efficient inactivation of the total coliforms in urban wastewater
Monitorable AIE polymers with a bioactive pattern are employed in advanced biomedical applications
such as functional coatings, theranostic probes, and implants. After the global COVID-19 pandemic,
interest in developing surfaces with superior antimicrobial, antiproliferative, and antiviral activities
dramatically increased. Many formulations for biocide surfaces are based on hybrid organic/inorganic
materials. Palladium (II) complexes display relevant activity against common bacteria, even higher
when compared to their uncoordinated ligands. This article reports the design and synthesis of two
series of orthopalladated polymers obtained by grafting a cyclopalladated fragment on two diferent
O, N chelating Schif base polymers. Diferent grafting percentages were examined and compared for
each organic polymer. The fuorescence emission in the solid state was explored on organic matrixes
and grafted polymers. DFT analysis provided a rationale for the role of the coordination core. The
antibacterial response of the two series of hybrid polymers was tested against the total coliform group
of untreated urban wastewater, revealing excellent inactivation abilit
A search for transits of GJ 581\lowercase{e} and characterization of the host star variability using MOST space telescope photometry
The GJ 581 system has been amply studied since its discovery in 2005: the
number of known planets in the system has increased and their orbital
parameters are among the most precisely determined for radial velocity detected
exoplanets. We have acquired MOST space-based photometry during 2007 and 2009,
with the aims of measuring the stellar variability and searching for transits
of GJ 581e, respectively. We quantify our sensitivity to shallow transit
signals using Monte Carlo simulations, and perform a transit search within the
3 transit windows corresponding to both the circular and Keplerian
orbit ephemerides. Our analysis rules out transits for a planet with an orbital
period of 3.15 days (GJ 581 e) having a radius larger than 1.62
(or a density lower than 2.39 g cm for an orbital inclination of
90) to 2 confidence. Thus, if the planet transits, we can
exclude hydrogen, helium and water theoretical model compositions. The MOST
photometry also allows us to rule out transits of GJ 581b within the Keplerian
orbit-derived transit window for impact parameter values smaller than 0.4
and confirm previous results which exclude transits for this planet within the
circular orbit-derived transit window, for all plausible interior compositions.
We find that the stellar brightness of GJ 581 is stable to within 1%, a
characteristic which is favourable to the development of life in the habitable
zone of the system. In the 2009 photometry, we detect a stellar signal with a
period of 5.586 0.051 days, which is close to the orbital period of GJ
581b (5.37 days). However, further monitoring of the system is necessary to
verify the nature of this variation.Comment: 11 pages, 2 tables, 10 figures; accepted for publication in Ap
Recommended from our members
Enteropathogen antibody dynamics and force of infection among children in low-resource settings.
Little is known about enteropathogen seroepidemiology among children in low-resource settings. We measured serological IgG responses to eight enteropathogens (Giardia intestinalis, Cryptosporidium parvum, Entamoeba histolytica, Salmonella enterica, enterotoxigenic Escherichia coli, Vibrio cholerae, Campylobacter jejuni, norovirus) in cohorts from Haiti, Kenya, and Tanzania. We studied antibody dynamics and force of infection across pathogens and cohorts. Enteropathogens shared common seroepidemiologic features that enabled between-pathogen comparisons of transmission. Overall, exposure was intense: for most pathogens the window of primary infection was <3 years old; for highest transmission pathogens primary infection occurred within the first year. Longitudinal profiles demonstrated significant IgG boosting and waning above seropositivity cutoffs, underscoring the value of longitudinal designs to estimate force of infection. Seroprevalence and force of infection were rank-preserving across pathogens, illustrating the measures provide similar information about transmission heterogeneity. Our findings suggest antibody response can be used to measure population-level transmission of diverse enteropathogens in serologic surveillance
A novel l-shaped fluorescent probe for aie sensing of zinc (Ii) ion by a dr/nir response
In the field of optical sensors, small molecules responsive to metal cations are of current interest. Probes displaying aggregation-induced emission (AIE) can solve the problems due to the aggregation-caused quenching (ACQ) molecules, scarcely emissive as aggregates in aqueous media and in tissues. The addition of a metal cation to an AIE ligand dissolved in solution can cause a “turn-on” of the fluorescence emission. Half-cruciform-shaped molecules can be a winning strategy to build specific AIE probes. Herein, we report the synthesis and characterization of a novel L-shaped fluorophore containing a benzofuran core condensed with 3-hydroxy-2-naphthaldehyde crossed with a nitrobenzene moiety. The novel AIE probe produces a fast colorimetric and fluorescence response toward zinc (II) in both in neutral and basic conditions. Acting as a tridentate ligand, it produces a complex with enhanced and red-shifted emission in the DR/NIR spectral range. The AIE nature of both compounds was examined on the basis of X-ray crystallography and DFT analysis
Vibrational analysis of paraelectric–ferroelectric transition of linbo3: An ab-initio quantum mechanical treatment
The phase transitions between paraelectric (PE) and ferroelectric (FE) isomorph phases of LiNbO3 have been investigated quantum mechanically by using a Gaussian-type basis set, the B3LYP hybrid functional and the CRYSTAL17 code. The structural, electronic and vibrational properties of the two phases are analyzed. The vibrational frequencies evaluated at the Γ point indicate that the paraelectric phase is unstable, with a complex saddle point with four negative eigenvalues. The energy scan of the A2u mode at −215 cm−1 (i215) shows a dumbbell potential with two symmetric minima. The isotopic substitution, performed on the Li and Nb atoms, allows interpretation of the nontrivial mechanism of the phase transition. The ferroelectric phase is more stable than the paraelectric one by 0.32 eV
Non-detection of previously reported transits of HD 97658b with MOST photometry
The radial velocity-discovered exoplanet HD 97658b was recently announced to
transit, with a derived planetary radius of 2.93 \pm 0.28 R_{Earth}. As a
transiting super-Earth orbiting a bright star, this planet would make an
attractive candidate for additional observations, including studies of its
atmospheric properties. We present and analyze follow-up photometric
observations of the HD 97658 system acquired with the MOST space telescope. Our
results show no transit with the depth and ephemeris reported in the
announcement paper. For the same ephemeris, we rule out transits for a planet
with radius larger than 2.09 R_{Earth}, corresponding to the reported 3\sigma
lower limit. We also report new radial velocity measurements which continue to
support the existence of an exoplanet with a period of 9.5 days, and obtain
improved orbital parameters.Comment: 16 pages, 4 figures; 1 Table; accepted for publication in ApJL,
includes changes made in response to the referee repor
Adrenocortical Serous Cystadenoma in a Cat
9-year-old, castrated male shorthair cat was referred for an abdominal mass accidentally palpated by the owner. Ultrasound showed a large inhomogeneous cystic mass close to the left kidney. A massive ablation of the mass was performed. Four days after surgery, the cat was severely azotemic and presented signs of multiple organ dysfunction. The cat was euthanized the 7th day after surgery. Histopathological examination was consistent for adrenocortical serous cystadenoma
Thermo-Induced Fluorochromism in Two AIE Zinc Complexes: A Deep Insight into the Structure-Property Relationship
Solid-state emitters exhibiting mechano-fluorochromic or thermo-fluorochromic responses represent the foundation of smart tools for novel technological applications. Among fluo-rochromic (FC) materials, solid-state emissive coordination complexes offer a variety of fluorescence responses related to the dynamic of noncovalent metal-ligand coordination bonds. Relevant FC behaviour can result from the targeted choice of metal cation and ligands. Herein, we report the synthesis and characterization of two different colour emitters consisting of zinc complexes obtained from N,O bidentate ligands with different electron-withdrawing substituents. The two complexes are blue and orange solid-state fluorophores, respectively, highly responsive to thermal and me-chanical stress. These emitters show a very different photoluminescent (PL) pattern as recorded before and after the annealing treatment. Through X-ray structural analysis combined with thermal analysis, infrared (IR) spectroscopy, PL, and DFT simulation we provide a comprehensive analysis of the structural feature involved in the fluorochromic response. Notably, we were able to correlate the on-off thermo-fluorochromism of the complexes with the structural rearrangement at the zinc coordination core
La Curva en S como Herramienta para la Medición de los Ciclos de Vida de Productos
The aim of this article was to carry out a study of the life cycles of three products of Colombian companies; based on a logistic model of population growth as a life cycles measurement tool. We found that the products life cycles have a similar behavior to the population growth, according to an S curve. The inflection points of the curves were obtained by a nonlinear regression. These points might be used as a tool for strategic decision making in products, in terms of identifying key instants for launching technological innovations, investments and execute marketing strategies
- …