Sculpting Windows onto AuAg Hollow Cubic Nanocrystals

Using surfactants in the galvanic replacement reaction (GRR) offers a versatile approach to modulating hollow metal nanocrystal (NC) morphology and composition. Among the various surfactants available, quaternary ammonium cationic surfactants are commonly utilised. However, understanding how they precisely influence morphological features, such as the size and void distribution, is still limited. In this study, we aim to uncover how adding different surfactants-CTAB, CTAC, CTApTS, and PVP-can fine-tune the morphological characteristics of AuAg hollow NCs synthesised via GRR at room temperature. Our findings reveal that the halide counterion in the surfactant significantly controls void formation within the hollow structure. When halogenated surfactants, such as CTAB or CTAC, are employed, multichambered opened nanoboxes are formed. In contrast, with non-halogenated CTApTS, single-walled closed nanoboxes with irregularly thick walls form. Furthermore, when PVP, a polymer surfactant, is utilised, changes in concentration lead to the production of well-defined single-walled closed nanoboxes. These observations highlight the role of surfactants in tailoring the morphology of hollow NCs synthesised through GRR

Modus vivendi de los mineros de carbón en la provincia del Sugamuxi en Boyacá – Colombia

La minería en los últimos años se ha convertido en un tema controversial, puesto que por una parte ha beneficiado económicamente al país y a las familias que dependen de esta actividad, pero también se ha evidenciado el daño ambiental que las malas prácticas y la poca responsabilidad social han hecho del sector y de la explotación minera una de las más discutidas. Por lo cual, con la presente investigación se exploran los diferentes conceptos, practicas, normas, estadísticas y caracterización del talento humano vinculado al trabajo de la minería de carbón en la provincia de Sugamuxi, caracterizada por ser de vocación minera y por ser la región objeto de estudio en el proyecto macro de caracterización minera. Se considera que, para alcanzar el objetivo de la investigación, se utilizó como instrumento de recolección de información la encuesta ajustada de RELAVE (2002), la cual como es un estudio en proceso se aplicó a 100 trabajadores de las minas de carbón de los municipios de Sogamoso (incluida Morca), Iza y Gameza distribuidos en 21 minas que se encuentran en dichos sectores

The Normative Implication of the B Corp Movement in the Business and Human Rights Context (abstract)

Over the past decades, issues of corporate accountability and social responsibility have risen to the forefront of international debate. The U.N. Guiding Principles on Business and Human Rights (Guiding Principles), endorsed by the U.N. HRC in June 2011, lays out authoritatively the state duty to protect and the corporate responsibility to respect human rights. In an effort to operationalize the Guiding Principles, the U.N. Working Group on Business and Human Rights has called on all states to develop a National Action Plan (NAP) regarding domestic implementation of the Guiding Principles. A key first-step in the creation of a NAP is the completion of a national baseline assessment, a taking of stock of the current conditions affecting the protection and promotion of human rights by the state and businesses alike. With over twenty-five countries now committed to the creation of a NAP, it is increasingly important to evaluate the existing corporate landscape, specifically structures that claim to be socially and ethically motivated. The B Corp movement began in 2006, through the work of California based non-profit B-Lab. A B Corp is a business certified by B-Lab as committed to creating and supporting social and environmental rights. The B Corp movement has grown in size and stature, spreading into over thirty countries and garnering a reputation for excellence. Boosts to the movement have recently come from the certification of large multinational companies, and the interest of others that followed. As the B Corp movement continues to proliferate, it’s normative value on the business and human rights field merits analysis. What are the normative implications of the B Corp movement?—Is it a tool that should be embraced by business and human rights activists or one that undermines the movement by enabling corporations to claim an inability to take into account ethical considerations without adoption of a special corporate form

Hollow metal nanostructures for enhanced plasmonics: synthesis, local plasmonic properties and applications

Hollow nanostructures; Surface plasmon resonances (SPRs); Plasmon hybridizationNanoestructures buides; Ressonància de superfície de plasmó; Hibridació de plasmóNanoestructures vacías; Resonancia de superficie de plasmón; Hibridación de plasmónMetallic nanostructures have received great attention due to their ability to generate surface plasmon resonances, which are collective oscillations of conduction electrons of a material excited by an electromagnetic wave. Plasmonic metal nanostructures are able to localize and manipulate the light at the nanoscale and, therefore, are attractive building blocks for various emerging applications. In particular, hollow nanostructures are promising plasmonic materials as cavities are known to have better plasmonic properties than their solid counterparts thanks to the plasmon hybridization mechanism. The hybridization of the plasmons results in the enhancement of the plasmon fields along with more homogeneous distribution as well as the reduction of localized surface plasmon resonance (LSPR) quenching due to absorption. In this review, we summarize the efforts on the synthesis of hollow metal nanostructures with an emphasis on the galvanic replacement reaction. In the second part of this review, we discuss the advancements on the characterization of plasmonic properties of hollow nanostructures, covering the single nanoparticle experiments, nanoscale characterization via electron energy-loss spectroscopy and modeling and simulation studies. Examples of the applications, i.e. sensing, surface enhanced Raman spectroscopy, photothermal ablation therapy of cancer, drug delivery or catalysis among others, where hollow nanostructures perform better than their solid counterparts, are also evaluated

Comentarios acerca de la nomenclatura estratigráfica del cretácico inferior del valle superior del magdalena

Las formaciones Yaví, Caballos y Hondita del Cretácico inferior del Valle Superior del Magdalena han sido objeto de estudios recientes, que aunque aportan información muy valiosa, son motivo de controversia.  En esta contribución se discuten las discrepancias existentes entre algunos de estos trabajos, en cuanto a correlaciones y nomenclatura estratigráfica se refiere.  Se recomienda el abandono del uso de varias unidades recientemente propuestas y se llama la atención sobre las definiciones originales de las unidades involucradas, de acuerdo con normas internacionales de procedimiento estratigráfico. Adicionalmente, se discuten las dataciones de dichas unidades, identificándose contradicciones que se adjudican al poco conocimiento de la dispersión temporal de algunos de los fósiles reportados.The lower Cretaceous Yaví, Caballos, and Hondita Formations have been recently studied.  Although these studies furnish valuable information, they are controversial.  In this paper we tackle the existing discrepancies in correlation and stratigraphic nomenclature.  The abandonement of recently proposed units is recommended and attention is called towards the original definitions, according to standard stratigraphic regulations.  In addition, biostratigraphical differences have been identified and discussed. They are ascribed to the poorly known ranges of the fossils reported

Optical inspection of liquid crystal variable retarder inhomogeneities

Liquid crystal variable retarders (LCVRs) are starting to be widely used in optical systems because of their capacity to provide a controlled variable optical retardance between two orthogonal components of incident polarized light or to introduce a known phase shifting (PS) between coherent waves, both by means of an applied voltage. Typically, the retardance or PS introduced by an LCVR is not homogeneous across the aperture. On the one hand, the LCVR glass substrates present a global bend that causes an overall variation of the retardance or PS. On the other hand, in the manufacturing process of an LCVR, there sometimes appears a set of micro-air bubbles that causes local retardance or PS inhomogeneities. In this work, we present an interferometric technique based on a Mach-Zehnder interferometer that is insensitive to vibrations and capable of inspecting and characterizing the LCVR's retardance or PS inhomogeneities. The feasibility of the proposed method is demonstrated in the experimental results, where the LCVR retardance is measured with an error of about 0:2 rad. The thickness of possible micro-air bubbles is obtained with a resolution of about 50 nm

Asymmetrical Plasmon Distribution in Hybrid AuAg Hollow/Solid Coded Nanotubes

Metal nanotubes; Nanotubes; NanowiresNanotubos metálicos; Nanotubos; NanocablesNanotubs metàl·lics; Nanotubs; NanofilsMorphological control at the nanoscale paves the way to fabricate nanostructures with desired plasmonic properties. In this study, we discuss the nanoengineering of plasmon resonances in 1D hollow nanostructures of two different AuAg nanotubes, including completely hollow nanotubes and hybrid nanotubes with solid Ag and hollow AuAg segments. Spatially resolved plasmon mapping by electron energy loss spectroscopy (EELS) revealed the presence of high order resonator-like modes and localized surface plasmon resonance (LSPR) modes in both nanotubes. The experimental findings accurately correlated with the boundary element method (BEM) simulations. Both experiments and simulations revealed that the plasmon resonances are intensely present inside the nanotubes due to plasmon hybridization. Based on the experimental and simulated results, we show that the novel hybrid AuAg nanotubes possess two significant coexisting features: (i) LSPRs are distinctively generated from the hollow and solid parts of the hybrid AuAg nanotube, which creates a way to control a broad range of plasmon resonances with one single nanostructure, and (ii) the periodicity of the high-order modes are disrupted due to the plasmon hybridization by the interaction of solid and hollow parts, resulting in an asymmetrical plasmon distribution in 1D nanostructures. The asymmetry could be modulated/engineered to control the coded plasmonic nanotubes.ICN2 acknowledges funding from the Generalitat de Catalunya 2021SGR00457. This study was supported by MCIN with funding from the European Union NextGenerationEU (PRTR-C17.I1) and the Generalitat de Catalunya. This research is part of the CSIC program for the Spanish Recovery, Transformation and Resilience Plan which is funded by the Recovery and Resilience Facility of the European Union and was established by Regulation (EU) 2020/2094. The authors are thankful for the support from the project NANOGEN (PID2020-116093RB-C43) which was funded by MCIN/AEI/10.13039/501100011033/, “ERDF A way of making Europe”, and the European Union. ICN2 is supported by the Severo Ochoa program at the Spanish MCIN/AEI (grant no. CEX2021-001214-S) and is funded by the CERCA Programme/Generalitat de Catalunya. R.A. acknowledges support from the Spanish MCIN (PID2019-104739GB-100/AEI/10.13039/501100011033), the Government of Aragon (project DGA E13-20R (FEDER, EU)), and the EU H2020 “ESTEEM3” (grant no. 823717). NGB and VP acknowledge financial support from the Spanish Ministerio de Ciencia, Innovación y Universidades (MCIU) (RTI2018-099965-B-I00, AEI/FEDER, UE)

Tailoring of the photocatalytic activity of CeO2 nanoparticles by the presence of plasmonic Ag nanoparticles

Altres ajuts: ICN2 is funded by the CERCA Programme/Generalitat de Catalunya.The present study investigates basic features of a photoelectrochemical system based on CeO nanoparticles fixed on gold electrodes. Since photocurrent generation is limited to the absorption range of the CeO in the UV range, the combination with metal nanoparticles has been studied. It can be shown that the combination of silver nanoparticles with the CeO can shift the excitation range into the visible light wavelength range. Here a close contact between both components has been found to be essential and thus, hybrid CeO@Ag nanoparticles have been prepared and analyzed. We have collected arguments that electron transfer occurs between both compositional elements of the hybrid nanoparticles.The photocurrent generation can be rationalized on the basis of an energy diagram underlying the necessity of surface plasmon excitation in the metal nanoparticles, which is also supported by wavelength-dependent photocurrent measurements. However, electrochemical reactions seem to occur at the CeO surface and consequently, the catalytic properties of this material can be exploited as exemplified with the photoelectrochemical reduction of hydrogen peroxide. It can be further demonstrated that the layer-by layer technique can be exploited to create a multilayer system on top of a gold electrode which allows the adjustment of the sensitivity of the photoelectrochemical system. Thus, with a 5-layer electrode with hybrid CeO@Ag nanoparticles submicromolar hydrogen peroxide concentrations can be detected

Tailoring of the photocatalytic activity of CeO2 nanoparticles by the presence of plasmonic Ag nanoparticles

Photocatalytic activity; NanoparticlesActividad fotocatalítica; NanopartículasActivitat fotocatalítica; NanopartículesThe present study investigates basic features of a photoelectrochemical system based on CeO2 nanoparticles fixed on gold electrodes. Since photocurrent generation is limited to the absorption range of the CeO2 in the UV range, the combination with metal nanoparticles has been studied. It can be shown that the combination of silver nanoparticles with the CeO2 can shift the excitation range into the visible light wavelength range. Here a close contact between both components has been found to be essential and thus, hybrid CeO2@Ag nanoparticles have been prepared and analyzed. We have collected arguments that electron transfer occurs between both compositional elements of the hybrid nanoparticles.The photocurrent generation can be rationalized on the basis of an energy diagram underlying the necessity of surface plasmon excitation in the metal nanoparticles, which is also supported by wavelength-dependent photocurrent measurements. However, electrochemical reactions seem to occur at the CeO2 surface and consequently, the catalytic properties of this material can be exploited as exemplified with the photoelectrochemical reduction of hydrogen peroxide. It can be further demonstrated that the layer-by layer technique can be exploited to create a multilayer system on top of a gold electrode which allows the adjustment of the sensitivity of the photoelectrochemical system. Thus, with a 5-layer electrode with hybrid CeO2@Ag nanoparticles submicromolar hydrogen peroxide concentrations can be detected.This work was supported by the Cluster of Excellence ‘Advanced Imaging of Matter’ of the Deutsche Forschungsgemeinschaft (DFG) – EXC 2056 – project ID 390715994. SZ acknowledges funding by the Chinese Scholarship Council (CSC). NGB and VP acknowledge financial support from the Spanish Ministerio de Ciencia, Innovación y Universidades (MCIU) (RTI2018-099965-B-I00, AEI/FEDER, UE). ICN2 is supported by the Severo Ochoa program from Spanish MINECO (SEV-2017-0706) and is funded by the CERCA Programme/Generalitat de Catalunya. ZY acknowledges support from the National Natural Science Foundation of China (Grant No. 61871240)

Exploring new synthetic strategies for the production of advanced complex inorganic nanocrystals

The design of new protocols for the colloidal synthesis of complex nanocrystals (NCs) with advanced functionalities, comprising both hybrid and hollow structures, and the study of their fundamental properties is of paramount importance for the development of a new generation of nanostructured materials. The possibility of tailoring the dimensional regime of NCs, along with its composition and structure, represents a landmark achievement in the control of their unique physico-chemical properties. These properties, alongside with the ability to cheaply produce high quality NCs in fairly large amounts by wet-chemistry techniques, leads to their potential applicability from materials science to nanomedicine. Within this context, this review is focused on describing a successful framework for designing synthetic strategies for the production of advanced complex NCs, integrating the development of new synthetic methods with its structural characterization, monitoring of their properties, and study of its reactivity. As a result, it is expected to provide new routes to produce robust and easy-to-process NCs in a wide range of sizes, shapes and configurations that can be explored to achieve the combination of all degrees of control, aiming to produce a complete and diverse library of material combinations that will expand its applicability in a wide diversity of fields