213 research outputs found
Disentangling instrumental broadening
A new procedure aiming at disentangling the instrumental profile broadening
and the relevant X-ray powder diffraction (XRPD) profile shape is presented.
The technique consists of three steps: denoising by means of wavelet
transforms, background suppression by morphological functions and deblurring by
a Lucy--Richardson damped deconvolution algorithm. Real XRPD intensity profiles
of ceria samples are used to test the performances. Results show the robustness
of the method and its capability of efficiently disentangling the instrumental
broadening affecting the measurement of the intrinsic physical line profile.
These features make the whole procedure an interesting and user-friendly tool
for the pre-processing of XRPD data.Comment: 9 pages, 1 table, 1 figure; typos correcte
The Chromosomal Protein Sso7d of the CrenarchaeonSulfolobus solfataricus Rescues Aggregated Proteins in an ATP Hydrolysis-dependent Manner
In this work, we show that the nonspecific DNA-binding protein Sso7d from the crenarchaeon Sulfolobus solfataricus displays a cation-dependent ATPase activity with a pH optimum around neutrality and a temperature optimum of 70 degrees C. Measurements of tryptophan fluorescence and experiments that used 1-anilinonaphthalene-8-sulfonic acid as probe demonstrated that ATP hydrolysis induces a conformational change in the molecule and that the binding of the nucleotide triggers the ATP hydrolysis-induced conformation of the protein to return to the native conformation. We found that Sso7d rescues previously aggregated proteins in an ATP hydrolysis-dependent manner; the native conformation of Sso7d forms a complex with the aggregates, while the ATP hydrolysis-induced conformation is incapable of this interaction. Sso7d is believed to be the first protein isolated from an archaeon capable of rescuing aggregates
Energy Transfer from Magnetic Iron Oxide Nanoparticles: Implications for Magnetic Hyperthermia
Magnetic iron oxide nanoparticles (IONPs) have gained momentum in the field of biomedical applications. They can be remotely heated via alternating magnetic fields, and such heat can be transferred from the IONPs to the local environment. However, the microscopic mechanism of heat transfer is still debated. By X-ray total scattering experiments and first-principles simulations, we show how such heat transfer can occur. After establishing structural and microstructural properties of the maghemite phase of the IONPs, we built a maghemite model functionalized with aminoalkoxysilane, a molecule used to anchor (bio)molecules to oxide surfaces. By a linear response theory approach, we reveal that a resonance mechanism is responsible for the heat transfer from the IONPs to the surroundings. Heat transfer occurs not only via covalent linkages with the IONP but also through the solvent hydrogen-bond network. This result may pave the way to exploit the directional control of the heat flow from the IONPs to the anchored moleculesâi.e., antibiotics, therapeutics, and enzymesâfor their activation or release in a broader range of medical and industrial applications
Site-occupancy factors in the Debye scattering equation : a theoretical discussion on significance and correctness
The Debye scattering equation (DSE) [Debye (1915). Ann. Phys. 351, 809-823] is widely used for analyzing total scattering data of nanocrystalline materials in reciprocal space. In its modified form (MDSE) [Cervellino et al. (2010). J. Appl. Cryst. 43, 1543-1547], it includes contributions from uncorrelated thermal agitation terms and, for defective crystalline nanoparticles (NPs), average site-occupancy factors (s.o.f.'s). The s.o.f.'s were introduced heuristically and no theoretical demonstration was provided. This paper presents in detail such a demonstration, corrects a glitch present in the original MDSE, and discusses the s.o.f.'s physical significance. Three new MDSE expressions are given that refer to distinct defective NP ensembles characterized by: (i) vacant sites with uncorrelated constant site-occupancy probability; (ii) vacant sites with a fixed number of randomly distributed atoms; (iii) self-excluding (disordered) positional sites. For all these cases, beneficial aspects and shortcomings of introducing s.o.f.'s as free refinable parameters are demonstrated. The theoretical analysis is supported by numerical simulations performed by comparing the corrected MDSE profiles and the ones based on atomistic modeling of a large number of NPs, satisfying the structural conditions described in (i)-(iii)
Ureaâfunctionalized amorphous calcium phosphate nanofertilizers: optimizing the synthetic strategy towards environmental sustainability and manufacturing costs
This work has been performed thanks to the funding by Fondazione CARIPLO (Project No. 2016-0648: Romancing
the stone: size-controlled HYdroxyaPATItes for sustainable Agriculture â HYPATIA). JMDL acknowledges
Spanish Ministry of Science, Innovation and Universities of Spain (MCIU/AEI/FEDER, UE) for funding through
the projects NanoVIT (RTI-2018-095794-A-C22) and NanoSmart (RYC-2016-21042). GBRR also acknowledges
the Spanish MICIU for her postdoctoral contract within the Juan de la Cierva Program (JdC-2017). Financial
support for this work was also provided by the Marie SkĆodowska-Curie Standard Fellowships (888972-PSust-
MOF, F.J.C.) within the European Union research and innovation framework programme (2014-2020). We thank
Prof. Jan Skov Pedersen (Aarhus University, DK) for technical and scientific assistance on SAXS experiments.Nanosized fertilizers are the new frontier of nanotechnology towards a sustainable agriculture. Here, an efficient N-nanofertilizer is obtained by post-synthetic modification (PSM) of nitrate-doped amorphous calcium phosphate (ACP) nanoparticles (NPs) with urea. The unwasteful PSM protocol leads to N-payloads as large as 8.1 w/w%, is well replicated by using inexpensive technical-grade reagents for cost-effective up-scaling and moderately favours urea release slowdown. Using the PSM approach, the N amount is ca. 3 times larger than that obtained in an equivalent one-pot synthesis where urea and nitrate are jointly added during the NPs preparation. In vivo tests on cucumber plants in hydroponic conditions show that N-doped ACP NPs, with half absolute N-content than in conventional urea treatment, promote the formation of an equivalent amount of root and shoot biomass, without nitrogen depletion. The high nitrogen use efficiency (up to 69%) and a cost-effective preparation method support the sustainable real usage of N-doped ACP as a nanofertilizer.Fondazione Cariplo
2016-0648Spanish Ministry of Science, Innovation and Universities of Spain (MCIU/AEI/FEDER, UE)
RTI-2018-095794-A-C22
RYC-2016-21042Marie Sklodowska-Curie Standard Fellowships within the European Union research and innovation framework programme (2014-2020)
888972-PSustMOFSpanish MICIU within the Juan de la Cierva Program (JdC-2017
Polyfluorinated Naphthalene-bis-hydrazimide for Solution-Grown n-Type Semiconducting Films
Naphthalene tetracarboxylic diimides (NDIs), possessing low-lying and tunable LUMO levels, are of wide interest for their aptitude to provide cost-effective, flexible, and environmentally stable n-type organic semiconductors through simple solution processing. NDI-based aromatic hydrazidimides are herein studied in relation to their chemical and environmental stability and as spin-coated stable thin films. In the case of the pentafluorinated residue, these were found to be crystalline, highly oriented, and molecularly flat (roughness = 0.3 nm), based on optical and atomic force microscopy, X-ray diffraction in specular and grazing incidence geometry, and X-ray reflectivity measurements. A new polymorph, previously undetected during the isolation of bulk powders or in their controlled thermal treatments, is found in the thin film and was metrically and structurally characterized from 2D GIWAXS patterns (monoclinic, P2/c, a = 17.50; b = 4.56; c = 14.24 & Aring;; beta = 84.8 degrees). This new thin-film phase, TF-F5, is formed no matter whether silicon, glass, or polymethylmethacrylate substrates are used, thus opening the way to the preparation of solution-grown flexible semiconducting films. The TF-F5 films exhibit a systematic and rigorous molecular alignment with both orientation and packing favorable to electron mobility (mu = 0.02 cm(2) V-1 s(-1)). Structural and morphological differences are deemed responsible for the absence of measurable conductivity in thin films of polyfluorinated analogues bearing -CF3 residues on the hydrazidimide aromatic rings
Urea-Doped Calcium Phosphate Nanoparticles as Sustainable Nitrogen Nanofertilizers for Viticulture: Implications on Yield and Quality of Pinot Gris Grapevines
In recent years, the application of nanotechnology for the development of new âsmart
fertilizersâ is regarded as one of the most promising solutions for boosting a more sustainable and
modern grapevine cultivation. Despite showing interesting potential benefits over conventional fertilization practices, the use of nanofertilizers in viticulture is still underexplored. In this work, we
investigated the effectiveness of non-toxic calcium phosphate nanoparticles (Ca3(PO4)2ânH2O)
doped with urea (U-ACP) as a nitrogen source for grapevine fertilization. Plant tests were performed for two years (2019â2020) on potted adult Pinot gris cv. vines grown under semi-controlled
conditions. Four fertilization treatments were compared: N1: commercial granular fertilization (45
kg N haâ1); N2: U-ACP applied in fertigation (36 kg N haâ1); N3: foliar application of U-ACP (36 kg
N haâ1); C: control, receiving no N fertilization. Plant nitrogen status (SPAD), yield parameters as
well as those of berry quality were analyzed. Results here presented clearly show the capability of
vine plants to recognize and use the nitrogen supplied with U-ACP nanoparticles either when applied foliarly or to the soil. Moreover, all of the qualiâquantitative parameters measured in vine
plants fed with nanoparticles were perfectly comparable to those of plants grown in conventional
condition, despite the restrained dosage of nitrogen applied with the nanoparticles. Therefore, these
results provide both clear evidence of the efficacy of U-ACP nanoparticles as a nitrogen source and
the basis for the development of alternative nitrogen fertilization strategies, optimizing the dosage/benefit ratio and being particularly interesting in a context of a more sustainable and modern
viticulture.PSR 2014/2020 Regione Autonoma Friuli Venezia GiuliaâMisure 16.1.1, DGR 1313/2018, DC 398/AGFOR 2020âGESOVIT PROJECTFondazione Cariplo, Italy, Grant n. 2016-0648, project: Romancing the stone: size controlled HYdroxyaPATItes for sustainable Agriculture (HYPATIA
Polymorphism in N,NâČ-dialkyl-naphthalene diimides
The long-known class of compounds called naphthalene diimides (NDI), bearing alkyl subtituents on the imide nitrogen atoms, have been widely used as active materials in thin film devices with interesting optical, sensing and electrical applications. Less is known about their rich crystal chemical behaviour, which comprises numerous polymorphic transitions, and the occurrence of elusive liquid crystalline phases. It is this behaviour which determines the response of the devices based on them. Here we fully characterized, by combining a combination of differential scanning calorimetry, powder and thin film diffraction and optical microscopy techniques, two newly synthetized NDI materials bearing n-octyl and n-decyl side-chains, as well as lighter analogues, of known room temperature crystal structures. In search for a rationale of their physico-chemical properties, phase stability and thermally induced solid-state transition reversibility, the differential behaviour of these NDI materials is here interpreted based on the competitive role of intermolecular pi-pi interactions and of the alkyl chains flexibility. The occurrence of comparable local minima of the molecular conformational energy hypersurface for shorter alkyls, and, for longer ones, of rotator phases, is here invoked
Correlative Light and Scanning X-Ray Scattering Microscopy of Healthy and Pathologic Human Bone Sections
Scanning small and wide angle X-ray scattering (scanning SWAXS) experiments were performed on healthy and pathologic human bone sections. Via crystallographic tools the data were transformed into quantitative images and as such compared with circularly polarized light (CPL) microscopy images. SWAXS and CPL images allowed extracting information of the mineral nanocrystalline phase embedded, with and without preferred orientation, in the collagen fibrils, mapping local changes at sub-osteon resolution. This favorable combination has been applied for the first time to biopsies of dwarfism syndrome and Paget's disease to shed light onto the cortical structure of natural bone in healthy and pathologic sections
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