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991.
Dr. Santiago E. Herrera Dr. Maximiliano L. Agazzi Dr. M. Lorena Cortez Dr. Waldemar A. Marmisollé Dr. Mario Tagliazucchi Dr. Omar Azzaroni 《Chemphyschem》2019,20(8):1044-1053
Ionically crosslinked poly(allylamine)/phosphate (PAH/Pi) colloids consist of self-assembled nanostructures stabilized by supramolecular interactions. Under physiological conditions, these interactions should be present at high ionic strength and only in a narrow pH window to be effective as drug delivery agents. In this work we study the effect of the pH and ionic strength in the chemical behaviour of inorganic phosphate (Pi), poly(allylamine hydrochloride) (PAH) and their mixture in aqueous solution (PAH−Pi). By combination of experimental measurements and a theoretical model, we demonstrate that the driving force that leads to the formation of colloids is the electrostatic pairing between the positively charged amino groups in PAH and negatively charged HPO42− ions. Increasing the ionic strength of the system by addition of KCl weakens the PAH−Pi interactions and narrows the pH stability window from 4 to 1.8 pH units. In addition, a fully reversible system was obtained in which the colloids assemble and disassemble by changing the pH between 6.8 and 7.1 at high ionic strength, making them suitable for use as pH-responsive nanocarriers. 相似文献
992.
Shikha Dhiman Teodora Andrian Beatriz Santiago Gonzalez Marrit M. E. Tholen Yuyang Wang Lorenzo Albertazzi 《Chemical science》2022,13(8):2152
The characterization of newly synthesized materials is a cornerstone of all chemistry and nanotechnology laboratories. For this purpose, a wide array of analytical techniques have been standardized and are used routinely by laboratories across the globe. With these methods we can understand the structure, dynamics and function of novel molecular architectures and their relations with the desired performance, guiding the development of the next generation of materials. Moreover, one of the challenges in materials chemistry is the lack of reproducibility due to improper publishing of the sample preparation protocol. In this context, the recent adoption of the reporting standard MIRIBEL (Minimum Information Reporting in Bio–Nano Experimental Literature) for material characterization and details of experimental protocols aims to provide complete, reproducible and reliable sample preparation for the scientific community. Thus, MIRIBEL should be immediately adopted in publications by scientific journals to overcome this challenge. Besides current standard spectroscopy and microscopy techniques, there is a constant development of novel technologies that aim to help chemists unveil the structure of complex materials. Among them super-resolution microscopy (SRM), an optical technique that bypasses the diffraction limit of light, has facilitated the study of synthetic materials with multicolor ability and minimal invasiveness at nanometric resolution. Although still in its infancy, the potential of SRM to unveil the structure, dynamics and function of complex synthetic architectures has been highlighted in pioneering reports during the last few years. Currently, SRM is a sophisticated technique with many challenges in sample preparation, data analysis, environmental control and automation, and moreover the instrumentation is still expensive. Therefore, SRM is currently limited to expert users and is not implemented in characterization routines. This perspective discusses the potential of SRM to transition from a niche technique to a standard routine method for material characterization. We propose a roadmap for the necessary developments required for this purpose based on a collaborative effort from scientists and engineers across disciplines.SRM, an advanced nanoscopy technique demands a transition from being a niche sophisticated technique to standard routine method for material characterization. The roadmap of necessary developments through multidisciplinary collaboration is discussed. 相似文献
993.
We construct a Koszul complex in the category of left skew polynomial rings associated with a flat endomorphism that provides a finite free resolution of an ideal generated by a Koszul regular sequence. 相似文献
994.
Gonzalez Zerbo Santiago Maestripieri Alejandra Martínez Pería Francisco 《Journal of Optimization Theory and Applications》2020,186(1):209-225
We study an extension to Krein spaces of the abstract interpolating spline problem in Hilbert spaces, introduced by M. Atteia. This is a quadratically constrained quadratic programming problem, where the objective function is not convex, while the equality constraint is sign indefinite. We characterize the existence of solutions and, if there are any, we describe the set of solutions as the union of a family of affine manifolds parallel to a fixed subspace, which depend on the original data.
相似文献995.
In the present work, we explore in photoanodes of dye-sensitized solar cell (DSSC) the co-sensitization of the red protein phycoerythrin extracted from Antarctic algae with spherical silver nanoparticles between 10 and 200 nm and triangular nanoparticles of ~100 nm. We found that the order of addition of the sensitizers matters. Best results achieved for a sequential approach was phycoerythrin used as a dipping solution at the first step and nanoparticles at the second. We found that cell efficiency depends on the protein concentration, although no main differences detected with the nanoparticle shape or size. Our results show an average increase of 25% in the conversion efficiency values in the presence of nanoparticles. 相似文献
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Jonathan P. H. Charmant Juan Fornis Julio Gmez Elena Lalinde M. Teresa Moreno A. Guy Orpen Santiago Solano 《Angewandte Chemie (International ed. in English)》1999,38(20):3058-3061
Enhanced reactivity is shown by uncoordinated C≡C bonds in the proximity of a metal in phosphanylacetylene complexes. cis-[Pt(C6F5)2(thf)2] reacts with [M(C6F5)2(PPh2C≡CPh)2] (M=Pt, Pd) to form binuclear complexes containing the novel 2,3-bis(diphenylphosphanyl)-1,3-butadien-1-yl bridging ligand. Substitution of the solvent ligands with, for example, PPh2H (see picture) provides species that could be characterized by X-ray crystallography. 相似文献
1000.
Santiago Melchor Ferrer Jose Molina Molina 《Journal of computational chemistry》1999,20(13):1412-1421
Density Functional Theory (DFT) calculations at the B3LYP/6-31G* level have been performed on four bowl-shaped polyaromatic hydrocarbons of C30H12 molecular formula ( 1 – 4 ) showing C3 ( 1 ), C2v ( 2 and 4 ), and C2h ( 3 ) symmetries. The geometrical and electronic properties of the compounds studied have been analyzed to explain their relative stability. NMR chemical shifts parameters for the atoms and Nucleus Independent Chemical Shifts (NICSs) for the rings were calculated using the GIAO method. The 13C and 1H chemical shifts calculated are in very good agreement with the experimental data. ©1999 John Wiley & Sons, Inc. J Comput Chem 20: 1412–1421, 1999 相似文献