3,212 research outputs found
Multifunctional metal-organic frameworks : from academia to industrial applications
After three decades of intense and fundamental research on metal-organic frameworks (MOFs), is there anything left to say or to explain? The synthesis and properties of MOFs have already been comprehensively described elsewhere. It is time, however, to prove the nature of their true usability: technological applications based on these extended materials require development and implementation as a natural consequence of the up-to-known intensive research focused on their design and preparation. The current large number of reviews on MOFs emphasizes practical strategies to develop novel networks with varied crystal size, shape and topology, being mainly devoted to academic concerns. The present survey intends to push the boundaries and summarise the state-of-the-art on the preparation of promising (multi) functional MOFs in worldwide laboratories and their use as materials for industrial implementation. This review starts, on the one hand, to describe several tools and striking examples of remarkable and recent (multi) functional MOFs exhibiting outstanding properties (e.g., in gas adsorption and separation, selective sorption of harmful compounds, heterogeneous catalysis, luminescent and corrosion protectants). On the other hand, and in a second part, it intends to use these examples of MOFs to incite scientists to move towards the transference of knowledge from the laboratories to the industry. Within this context, we exhaustively review the many efforts of several worldwide commercial companies to bring functional MOFs towards the daily use, analysing the various patents and applications reported to date. Overall, this review goes from the very basic concepts of functional MOF engineering and preparation ending up in their industrial production on a large scale and direct applications in society
New magnetotelluric data through the boundary between the Ossa Morena and Centroiberian Zones
The south-western part of the Iberian Peninsula, including the southern branch of the Iberian Massif, has recently been the subject of several magnetotelluric (MT) studies. This area is made up of three different tectonic terranes: the South Portuguese Zone (SPZ), the Ossa Morena Zone (OMZ) and the Central Iberian Zone (CIZ). The boundaries between these zones are considered to be sutures, which appear as high electrical conductivity anomalies in the MT surveys. The OMZ is characterised by a conductive layer at middle-lower crustal levels. To investigate the continuity of this conductive layer into the CIZ, a new MT profile was carried out. This 75-km long ENE profile goes through the boundary between the OMZ and the CIZ. The results of a two-dimensional magnetotelluric inversion revealed a high-conductivity anomaly in the transition OMZ/CIZ (the so-called Central Unit), which is interpreted as due to interconnected graphite along shear planes. High-conductivity anomalies appeared in the middle crust of the CIZ, whose geometry and location are consistent with the conductive layer previously found in the OMZ, thus confirming the prolongation of the conductive layer into the CIZ. The top of this layer correlated spatially with a broad reflector detected by a seismic profile previously acquired in the same area. This, together with other geological and petrological evidence, points to a common origin for both features
catena-[1,3-diammoniopropane di-mu2-hydroxodi-mu4-phosphato-trioxotrivanadium dihydrate]: a redetermination at 180 (2) K
The crystal structure of the title compound, (C3H12N2)-
[V3O3(OH)2(PO4)2] 2H2O, has been reported by Soghomonian
et al. [Chem. Mater. (1993), 5, 1690±1691]. We present
here a redetermination of greatly improved precision and at a
low temperature of 180 (2) K. The H atoms connected to
oxygen have been successfully located and the coordination
environments of the two crystallographically independent
vanadium centres have been properly elucidated. Large
channels, running along the a direction, contain water
molecules and 1,3-diammoniopropane cations that are
strongly hydrogen bonded to the anionic framework through
N+ÐH O and OÐH O interactions. One vanadyl (V O)
bond and the central ±CH2± group of 1,3-diammoniopropane
are located on a mirror plane
Noise models for superoperators in the chord representation
We study many-qubit generalizations of quantum noise channels that can be
written as an incoherent sum of translations in phase space. Physical
description in terms of the spectral properties of the superoperator and the
action in phase space are provided. A very natural description of decoherence
leading to a preferred basis is achieved with diffusion along a phase space
line. The numerical advantages of using the chord representation are
illustrated in the case of coarse-graining noise.Comment: 8 pages, 5 .ps figures (RevTeX4). Submitted to Phys. Rev. A. minor
changes made, according to referee suggestion
Synthesis of 3-indolylazoles and meridianin derivatives from indolyl enaminonitriles
The reaction of indole derivatives with cyanoacetic acid followed by treatment with DMFDMA gave the intermediate indolyl enaminonitriles (3). Further reaction with aminoguanidine yielded 5´-cyanomeridianin analogues (4). The same intermediate reacted with p-methoxyphenylhydrazine to give the pyrazolyl derivative (8).
Treatment of (2E)-3-dimethylamino-2-(1H-indol-3-yl)-propenoate (3a) with hydroxylamine hydrochloride in basic medium afforded (5-amino-isoxazol-4-yl)-(1H-indol-3-yl)-methanone (5) and the acrylic acid derivative (6) after a short or a long heating, respectively. Unequivocal structural elucidation of the latter compound was achieved from single-crystal X-ray diffraction studies.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BPD/31490/2006FEDER - REEQ/ 630/QUI/200
Heterodimetallic germanium(IV) complex structures with transition metals
The hydrothermal synthesis and structural characterization of a number of complex compounds containing the
divalent tris(oxalato-O,O¢)germanate anion, [Ge(C2O4)3]2-, or the neutral bis(oxalate-O,O¢)germanium fragment,
[Ge(C2O4)2], with transition-metal (M) cationic complexes of 1,10¢-phenanthroline (phen) is reported: [M(phen)3]-
[Ge(C2O4)3]âxH2O [where M2+ ) Cu2+ (1a and 1b), Fe2+ (2a and 2b), Ni2+ (3), Co2+ (4); x ) 0.2 for 2b], [MGe-
(phen)2(í2-OH)2(C2O4)2] [where M2+ ) Cd2+ (5) and Cu2+ (6)]. The isolation of two polymorphs with Cu2+ (1a and
1b) and other pseudo-polymorphs for Fe2+ (2a and 2b) was rationalized based on slightly different molar ratios for
the starting materials. All compounds have been characterized using EDS, SEM, vibrational spectroscopy (FT-IR
and FT-Raman), thermogravimetry, and CHN elemental composition and their structure determined on the basis
of single-crystal X-ray diffraction studies. The crystal packing of the different chemical moieties for each series of
compounds was discussed on the basis of the various intermolecular interactions present (strong C-Hâââð and
weak C-HâââO hydrogen-bonding interactions, C-Hâââð and ð-ð contacts).FCT - SFRH/BPD/9309/2002FCT - SFRH/BPD/14410/2003FEDERPOCI - 201
Mixedness and entanglement for two-mode Gaussian states
We analytically exploit the two-mode Gaussian states nonunitary dynamics. We
show that in the zero temperature limit, entanglement sudden death (ESD) will
always occur for symmetric states (where initial single mode compression is
) provided the two mode squeezing satisfies We also give the analytical expressions for the time of ESD.
Finally, we show the relation between the single modes initial impurities and
the initial entanglement, where we exhibit that the later is suppressed by the
former.Comment: Accepted for publication in Optics Communication
Search for blue compact dwarf galaxies during quiescence II: metallicities of gas and stars, ages, and star-formation rates
We examine the metallicity and age of a large set of SDSS/DR6 galaxies that
may be Blue Compact Dwarf (BCD) galaxies during quiescence (QBCDs).The
individual spectra are first classified and then averaged to reduce noise. The
metallicity inferred from emission lines (tracing ionized gas) exceeds by ~0.35
dex the metallicity inferred from absorption lines (tracing stars). Such a
small difference is significant according to our error budget estimate. The
same procedure was applied to a reference sample of BCDs, and in this case the
two metallicities agree, being also consistent with the stellar metallicity in
QBCDs. Chemical evolution models indicate that the gas metallicity of QBCDs is
too high to be representative of the galaxy as a whole, but it can represent a
small fraction of the galactic gas, self enriched by previous starbursts. The
luminosity weighted stellar age of QBCDs spans the whole range between 1 and 10
Gyr, whereas it is always smaller than 1 Gyr for BCDs. Our stellar ages and
metallicities rely on a single stellar population spectrum fitting procedure,
which we have specifically developed for this work using the stellar library
MILES.Comment: Accepted for publication in ApJ. 20 pages. 16 figures (corrected
typos
Comparing effects of tillage treatments performed with animal tractionon soil physical properties: preliminary experimental results
La compactación del suelo es causada por las fuerzas que compresión aplicadas al suelo mediante la maquinaria agrícola así como las operaciones de labrado, siendo particularmente preocupantes cuando el suelo está húme-
do y sufre más riesgos de deformación. La tracción animal (e incluso la humana) también puede causarla, si bien no ha sido estudiada en profundidad. Hoy en día la tracción animal surge como alternativa sostenible a la meca-
nizada, en especial en áreas de montaña. Este estudió se llevo a cabo para evaluar el impacto en la compacta-
ción del suelo del laboreo utilizando tracción mecánica y tracción animal. La parcela estudiada está situada en Vale de Frades, NE de Portugal. En ella se aplicaron los tratamientos en sub-parcelas (30x3m), que consistían en dos pases con tractor, un par de vacas y un par de burros; siendo los aperos de volteo (arado romano) y de corte (cultivador y escarificador). Se tomaron 120 muestras de suelo antes y después de las labores para estu-
diar diferentes propiedades físicas del suelo: densidad aparente, porosidad y conductividad hidráulica.Los resul-
tados de este ensayo si bien parecen mostrar la tracción animal como una alternativa sostenible a la motoriza-
ción, no son todavía concluyentes, haciendo necesarios estudios futuros.info:eu-repo/semantics/publishedVersio
Tetrabutylammonium 2,6-dihydroxybenzoate 2,6-dihydroxybenzoic acid solvate
The title compound, C16H36N+ C7H5O4
ÿ C7H6O4 or
(nBu4N)+ (2,6-dhb)
ÿ (2,6±Hdhb) [where (nBu4N) is tetrabutylammonium,
(2,6-dhb)
ÿ
is 2,6-dihydroxybenzoate and
(2,6-Hdhb) is 2,6-dihydroxybenzoic acid], crystallizes in the
space group P1. The crystal structure involves alternate layers,
in the c direction, of cationic [nBu4N]n
n+ and anionic [(2,6-
dhb)(2,6-Hdhb)]n
nÿ
. Hydrogen bonds within the anionic layers
form bridges between 2,6-Hdhb and 2,6-dhb
ÿ
residues
- …
