Photochromic materials via sol-gel process

Powders and thin films of photochromic glasses containing AgBr or AgCl microcrystals were synthesized via sol-gel process. Up to 10 wt%, of Ag⁺, bonded with suitable complexing agents, were introduced into the matrix system consisting of xSiO₂-(1 - x)Al₂O₃ (x = 0.7... 1). After drying and heat treatment the AgX microcrystals (X = Cl, Br) were characterized by X-ray diffraction and high-resolution TEM. The photochromic properties were measured using a diode array UV-VIS spectrometer

Sol-gel derived coatings with completely reversible photochromism

Besides the photochromic glasses based on silver halides especially the cuprous halide containing materials are of practical importance. Due to their high absorption coefficient the cuprous halides are particularly suited for the preparation of thin photochromic films. Using the sol-gel technique silicon alkoxide based coating solutions with continuously distributed photoactive components were prepared. From these sols single or multilayer coatings were produced by dipping. The precipitation of the cuprous halide microcrystals as carriers of the photochromic properties of the coatings proceeded during a subsequent heat treatment (temperature range of 100 to 800 °C). Thus it was possible for the first time to produee photochromic coatings with a pronounced darkening and with complete reversibility of the photochromic reactions at room temperature

La necesidad de regular los puertos privados que presten servicios públicos

Actualmente, la Ley del Sistema Portuario Nacional (LSPN) y su Reglamento (RLSPN) contemplan dos modalidades de inversión privada en infraestructura portuaria para la atención de carga de terceros. La primera se encuentra dentro del régimen de asociaciones público privadas y en el Perú únicamente se ha presentado a través de la figura de las concesiones. La segunda modalidad se refiere al régimen de autorizaciones administrativas y se ha presentado en el Perú esencialmente para la implementación de puertos privados de uso privado. Estas modalidades se diferencian básicamente en: los requisitos necesarios para obtener el título habilitante (contrato de concesión vs. licencia portuaria); las obligaciones que asume el operador portuario frente al Estado peruano; el régimen de penalidades/sancionador al que se sujetan; y las inversiones que se encuentran obligados a efectuar. El objeto de la investigación está estrechamente vinculado a los puertos privados marítimos y a los servicios que éstos prestan a terceros no vinculados. De acuerdo con la Resolución de Acuerdo de Directorio No. 080-2017-APN/DIR, existen 59 terminales portuarios de ámbito marítimo, de los cuales, 33 son de titularidad privada de uso privado. A través de este trabajo hemos tenido una aproximación de cuántos de estos puertos prestan servicios a terceros no vinculados así como el volumen de carga que transportan a través de éstos

Dynamics of Competitive Evolution on a Smooth Landscape

We study competitive DNA sequence evolution directed by {\it in vitro} protein binding. The steady-state dynamics of this process is well described by a shape-preserving pulse which decelerates and eventually reaches equilibrium. We explain this dynamical behavior within a continuum mean-field framework. Analytical results obtained on the motion of the pulse agree with simulations. Furthermore, finite population correction to the mean-field results are found to be insignificant.Comment: 4 pages, 2 figures, revised, to appear in Phys. Rev. Let

Poetics/Poelitics of materiality in latin american digital poetry

Este artículo propone leer la poesía digital latinoamericana en vinculación con el acontecimiento poético-político que emerge cuando se considera su materialidad. Dar visibilidad a la materialidad habilita limitar la naturalización de los sentidos que vienen asociados a la cultura digital hegemónica contemporánea. Esto se logra desde procedimientos que ponen de relieve tanto los diversos niveles de materialidad inherentes a cada evento artístico literario digital —materialidad textual de superficie, materialidad relacional de las interfaces tanto de software como de hardware, materialidad del código— como los modos convencionales de ser con y hacer sentido de los entramados técnicos digitales que organizan nuestra vida cotidiana.This paper aims to read Latin American digital poetry in regards to the poetic-political event that emerges whenever its materiality is considered. To make materiality visible enables one to restrict the naturalization of meanings associate with contemporary hegemonic digital culture. This is accomplished through artistic procedures that emphasize, on the one hand, the multiple levels of materiality inherent to digital literary works— surface/textual materiality, software and hardware interface relational materiality, code materiality—and, on the other hand, the conventional ways to interact with and build meaning within the digital space that organize everyday life.Fil: Kozak, Claudia. Universidad de Buenos Aires. Facultad de Ciencias Sociales. Instituto de Investigaciones "Gino Germani". Estudios Culturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tres de Febrero; Argentin

Investigations into structure and composition of gel layers on medieval window glasses of the Katharinenkirche, Oppenheim (Germany), and the Cathedral St. Gatien, Tours (France)

Optical microscopy, Scanning Electron Microscopy (SEM), X-Ray Diffraction analysis (XRD) and Energy dispersive electron Probe Micro Analysis (EPMA) were used to characterize surface and subsurface layers and areas on medieval church window glasses generated by weathering and contamination, respectively. Investigations were carried out at surfaces and at existing or at artificially created cross-sections as well. Altogether 30 samples (22 from the Katharinenkirche, Oppenheim (Germany), and eight from the Cathedral St. Gatien, Tours (France)) were at disposal for the investigations. Depending on possibilities, conceded by the decisions of the responsible curators of the named historical monuments, investigations were carried out to get as much information as possible about chemical and structural characteristics of defects of the authentic glasses caused by weathering processes. In case of their appearance and detectability so-called gel layers or gel areas were of special interest. With attention to the specific conditions, samples were characterized with respect to the documentation of topographic changes of their surfaces (SEM), the detection and characterization of crystalline phases (XDA), the determination of compositions of the genuine glasses as well as material areas caused by weathering (EPMA). Using records of element-specific mappings, information about depth-dependent element distribution profiles was accessible