Display omitted
•A porous polyvinyl-chloride membrane able of sequestering metal ions was realized.•Microporosity (≈2 µm) was obtained adding Poly vinyl alcohol (PVA) as blend.•Protophorphyrin IX was ...used as ionophore.•The presence of PVA and ionophore does not decrease the thermal field of application.•The effective complexion with metal ions was verified by UV.
The purpose of this work is to create a porous polyvinyl-chloride (PVC) membrane able of sequestering metal ions in solution avoiding the use of plasticizers that can affect ionophores distribution and performance. In the sensor here developed, the distribution of ionophore (i.e. protoporphyrin IX) is no longer due to plasticizers but to microcavities that allow it to easily penetrate inside the material. Microporosity was obtained adding water soluble components (Poly vinyl alcohol or NaHCO3) as blends or crystals to PVC. Only blends show a uniformly distributed porosity (≈2 µm), that allows a rapid exchange thanks to the increased active surface. Membranes were characterized by Infrared Spectroscopy (IR), Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM). The effective complexion with metal ions was verified by IR and UV Spectroscopy.
The addition of a solution of terpy (2,2′;6′,2″-terpyridine) to a solution of
cis-PtCl
2(dmso)
2 (dmso, dimethylsulfoxide) in acetone, at 25°C, brought to the formation of PtCl(terpy)PtCl
3(dmso) (
...1), as a high yield crystalline red powder, within 12 h. Single crystals of
1 suitable for X-ray diffraction studies were obtained from dmso solution and contain chains of PtCl(terpy)
2
2+
dimers (Pt–Pt, 2.338(1) Å) with a Pt⋯Pt inter-dimer contact distance of 3.419(1) Å. The PtCl(terpy)
+ moieties have a head-to-tail disposition throughout the chains. The PtCl
3(dmso)
− anions do not have any short internuclear contact but are associated with the chains of cations via (terpy)C–H⋯Cl and (terpy)C–H⋯O hydrogen bond type interactions. The PtCl(terpy)
+ moiety has been simulated via the density functional methods at the B3LYP/LANL2DZ level (6-31G** for Cl), applied to model systems such as PtCl(NH
2)
3
2−, Pt(H
2O)
4
2+, PtCl(H
2O)
3
+, PtCl(NHCH–CHN–C(CH
2)–CHNH)
+, {PtCl(NH
2)
3}{Pt(H
2O)
4}, {PtCl(H
2O)
2(NH
2)}{PtCl(NH
2)
3
2−, PtCl(H
2O)
3
2
2+
, PtCl(NHCH–CHN–C(CH
2)–CHNH)
2
2+
. The computed structure for PtCl(NHCH–CHN–C(CH
2)–CHNH)
+ reproduces well the corresponding moiety of the PtCl(terpy)
+ cation; for instance, the computed Pt–Cl distance is 2.305 Å, just 0.006 Å smaller than the value found for
1. The optimization of the {PtCl(NH
2)
3}{Pt(H
2O)
4} neutral molecule which consists of a dianion and a dication brought to a dimer whose Pt–Pt distance is 3.079 Å, much smaller than twice the Van der Waals radius for Pt (1.7–1.8 Å).
Hybrid hydrogels were synthesized mixing poly(vinyl alcohol) (PVA) and xanthan gum (XG) in different molar ratios and using trisodium trimetaphosphate, as crosslinking agent, to obtain potential ...nucleus pulposus substitutes. Human Nucleus Pulposus (NP) is a hydrogel-like tissue with peculiar properties, which determine its role in supporting and dissipating spinal loads. Hydrogel obtained mixing PVA and XG in molar ratio 4:1 (PX25) showed mechanical, swelling, and thermal properties, i.e., heat capacity, which make it a good candidate as a potential NP substitute. Preliminary cytotoxicity tests pointed out that the developed materials did not show any signs of cytotoxicity towards NIH3T3 cells.
Typically, automatic telemetry monitoring in space operations is performed by out‐of‐limits (OOL) alarms. This approach consists of defining an upper and lower threshold so that when a measurement ...goes above the upper limit or below the lower one, an alarm is triggered. We discuss the limitations of the out‐of‐limits approach and propose a new monitoring paradigm based on novelty detection. The proposed monitoring approach can detect novel behaviors, which are often signatures of anomalies, very early — allowing engineers in some cases to react before the anomaly develops. A prototype implementing this monitoring approach has been implemented and applied to several ESA missions. The operational assessment from the XMM‐Newton operations team is presented.
Display omitted
•Benzofulvene derivatives 6-Pyr-BF3k and 6-PTPC-BF3k bearing uncomplexed and complexed pyridine rings are synthesized.•The solvent removal from a 6-Pyr-BF3k solution leads to the ...spontaneous formation of the homopolymer poly-6-Pyr-BF3k.•The same procedure applied to the 6-PTPC-BF3k monomer highlights the competition between polymerization and crystallization.•Uncomplexd poly-6-Pyr-BF3k show interesting emission properties, while poly-6-PTPC-BF3k shows low emission quantum yield.
Benzofulvene derivatives bearing complexed and un-complexed pyridine rings are designed and synthesized to assess the effects on the spontaneous solid-state polymerization of the presence in position 6 of the 3-phenylbenzofulvene moiety of bulky substituents capable of establishing metallophilic interactions. Both the benzofulvene monomers are found to polymerize spontaneously upon solvent removal under reduced pressure in the apparent absence of catalysts or initiators. The resulting polybenzofulvene derivatives are characterized by NMR spectroscopy, MALDI-TOF mass spectrometry, and in photophysical studies.
Summary
The main aim of this work was to evaluate the leaching of copper in grappa from distillation plant that treats Cabernet and Sangiovese marcs (Montepulciano and Chianti, Tuscany). Copper ...content (determined by atomic absorption spectrometry, AAS) was 1.05 ± 0.03 mg L−1 in industrial distillates (Cabernet marc, 82.3% alcohol, v/v), and 3.7 ± 0.2 μg L−1 in artificial grappa (62.0%, Cabernet) obtained by distilling marc in a laboratory‐scale glassware plant. The artificial grappa distillate was refluxed over copper shavings, and copper content, CCu, was analysed in relation to reflux time and wear of the copper bell. The results showed that CCu trend was almost linear with increasing alcohol concentration and constant reflux time, and vice versa. The ratios of selected volatile components were not influenced by reflux on the shavings.
This study reports on the study of copper release from Cu‐surfaces of industrial distillation plants, into grape marc distillate (Grappa). The tuning of distillate/Cu‐surfaces contact time and influence of alcohol contents, and pH, in distillation processes for Grappa are also reported.
Display omitted
•Neutral platinum(II) complex 2-PTPC-BF3a was prepared from benzofulvene derivative 2-Pyr-BF3a.•Complex 2-PTPC-BF3a was found to aggregate into an ordered crystalline solid-state ...without significant spontaneous polymerization.•Crystalline powder of 2-PTPC-BF3a is insensible to UV-light irradiation, while its dispersions in chloroform produced the corresponding polymer poly-2-Pyr-BF3a.•Curiously, the UV-light irradiation of the crystalline films deposited from THF solutions on quartz substrates produce oligomers of poly-2-PTPC-BF3a which show significant emission.
Neutral platinum(II) complex 2-PTPC-BF3a was easily prepared from benzofulvene derivative 2-Pyr-BF3a in order to evaluate the effects in the aggregation/polymerization behavior of a bulky substituent capable of establishing intermolecular metal–metal interactions in the close proximity of the putative polymerization center. Complex 2-PTPC-BF3a was found to aggregate into an ordered crystalline solid-state without significant spontaneous polymerization, but the UV-light irradiation of its dispersions in chloroform produced corresponding oligomers, which were characterized by NMR spectroscopy and MALDI-TOF mass spectrometry. On the other hand, the UV-irradiation of the platinum complex in the solid-state produced different results probably depending on the aggregate architecture. Notably, the crystalline films deposited from THF solutions on quartz substrates showed weak emissions, which progressively increased upon irradiation with the formation of oligomers devoid of the aggregation-induced quenching sites that seemed to affect the emission of poly-2-PTPC-BF3a. Finally, DFT calculations were performed on platinum complex 2-PTPC-BF3a in the aim of rationalizing the observed photophysical features.
Proteins in solution affect the structural and dynamic properties of the bulk water at the protein-water interface, resulting in a contribution to the order of the hydration water. Theoretical and ...experimental NMR relaxation methods were developed to study the dynamic properties of water molecules in the protein hydration shell. Water non-selective and selective relaxation rates, were shown to be sensitive to contributions from ordered solvent molecules at protein surface. The average rotational correlation time of water molecules in the protein hydration shell was determined for three protein systems of different size: ribonuclease A, human serum albumin and fibrinogen. The knowledge of these properties is an important step toward the determination of the size of the water ordering contributions originate in proteins systems.
Display omitted
•An NMR relaxometry method was developed.•Water molecules ordering contribution is a function of protein size and conformation.•Average correlation time of water molecules in protein hydration layers was studied.
INTEGRAL (INTErnational Gamma-Ray Astrophysics Laboratory) is an astronomical observatory of the European Space Agency, responsible for many significant scientific discoveries in the last few ...decades. It orbits Earth since 2002 in a highly elliptical orbit, passing through the Van Allen belts – areas with high-energy ionized particles that can damage the spacecraft’s on-board equipment. An essential part of mission planning and operation of INTEGRAL is thus the prediction of its radiation belts entry and exit times. We propose a novel compact representation of the data and evaluate its potential using several machine learning methods. The experimental validation identifies gradient boosted trees with quantile loss as the best performing method. By using our approach, INTEGRAL can perform 2 additional hours (on average) of scientific measurements per orbit (with adjustment for uncertainty at the 95th percentile). This approach protects INTEGRAL from damages and improves its scientific return at the same time. It can be easily extended and applied to other spacecraft with similar orbits.
PVA based hydrogels were synthesised using, as crosslinking agent, trisodium trimetaphosphate (STMP) to obtain potential substitutes for the vitreous body of the eye. The hydrogels, obtained using ...different amounts of STMP, were characterised by Infrared Spectroscopy which confirmed the successful occurrence of crosslinking reaction. The mechanical spectra of the fully hydrated samples confirmed covalently crosslinked systems (i.e. G′ > G″). The rheological analysis pointed out that only one of the hydrogels (PVA STMP 8:1) showed a behaviour similar to that of human vitreous. The hydrogel was also subjected to injection through a small needle, a procedure that is essential in the use of vitreous substitutes. Further analysis in terms of light transmittance, water content measurements, diffusion coefficient and cytotoxicity confirmed the applicability of such a hydrogel as vitreous substitute.
PDF
