Structural transformations in Cu, Ag, and Au metal nanoclusters

Finite-temperature structures of Cu, Ag, and Au metal nanoclusters are calculated in the entire temperature range from 0 K to melting using a computational methodology that we proposed recently [Settem \emph{et al.}, Nanoscale, 2022, 14, 939]. In this method, Harmonic Superposition Approximation (HSA) and Parallel Tempering Molecular Dynamics (PTMD) are combined in a complementary manner. HSA is accurate at low temperatures and fails at higher temperatures. PTMD, on the other hand, effectively samples the high temperature region and melting. This method is used to study the size- and system-dependent competition between various structural motifs of Cu, Ag, and Au nanoclusters in the size range 1 to 2 nm. Results show that there are mainly three types of structural changes in metal nanoclusters depending on whether a solid-solid transformation occurs. In the first type, global minimum is the dominant motif in the entire temperature range. In contrast, when a solid-solid transformation occurs, the global minimum transforms either completely to a different motif or partially resulting in a co-existence of multiple motifs. Finally, nanocluster structures are analyzed to highlight the system-specific differences across the three metals.Comment: The following article has been accepted by Journal of Chemical Physics. After it is published, it will be found at https://doi.org/10.1063/5.0159257. Accepted version of the manuscript (along with supplementary material) consists of 32 pages, 11 figure

Exploring the potential of peach (Prunus Persica L.) nut-shells as a sustainable alternative to traditional aggregates in lightweight concrete

This study investigates the potential application of peach shells as lightweight aggregates in the production of non-structural lightweight concrete (LWC). The recycling and reutilization of agri-food waste presents an opportunity to address the challenges associated with waste disposal and limit the exploitation of natural resources, contributing to sustainable development goals and combatting climate change. The peach shells were subjected to heat treatment at various temperatures (160, 200, and 240 °C) to reduce the hydrophilicity of the cellulose fraction, and their chemical and physical properties were examined in relation to the performance of lightweight concrete, in terms of density, compressive strength and thermal conductivity. Two binding mixtures, one with lime only (mixture “a”) and the other with both lime and cement (mixture “b”), were studied. The experimental results indicated that the prepared lightweight concrete specimens exhibited better performance as the roasting temperature increased, starting from 200 °C. Conversely, specimens prepared with peach shells roasted at 160 °C exhibited a decreased performance compared to those prepared with only air-dried peach shells. Samples prepared with the mixture “a” have better insulating properties and lower density, but lower mechanical resistance. The enhanced properties observed in the lightweight concrete specimens prepared with higher roasting temperatures highlight the potential of utilizing peach shells as an effective and sustainable alternative to traditional lightweight aggregates

Upgrading of Biobased Glycerol to Glycerol Carbonate as a Tool to Reduce the CO2 Emissions of the Biodiesel Fuel Life Cycle

With regards to oil-based diesel fuel, the adoption of bio-derived diesel fuel was estimated to reduce CO2 emissions by approximately 75%, considering the whole life cycle. In this paper, we present a novel continuous-flow process able to transfer an equimolar amount of CO2 (through urea) to glycerol, producing glycerol carbonate. This represents a convenient tool, able to both improve the efficiency of the biodiesel production through the conversion of waste streams into added-value chemicals and to beneficially contribute to the whole carbon cycle. By means of a Design of Experiments approach, the influence of key operating variables on the product yield was studied and statistically modeled

Single cell oils of the cold-adapted oleaginous yeast Rhodotorula glacialis DBVPG 4785

<p>Abstract</p> <p>Background</p> <p>The production of microbial lipids has attracted considerable interest during the past decade since they can be successfully used to produce biodiesel by catalyzed transesterification with short chain alcohols. Certain yeast species, including several psychrophilic isolates, are oleaginous and accumulate lipids from 20 to 70% of biomass under appropriate cultivation conditions. Among them, <it>Rhodotorula glacialis </it>is a psychrophilic basidiomycetous species capable to accumulate intracellular lipids.</p> <p>Results</p> <p><it>Rhodotorula glacialis </it>DBVPG 4785 is an oleaginous psychrophilic yeast isolated from a glacial environment. Despite its origin, the strain abundantly grew and accumulated lipids between -3 to 20°C. The temperature did not influence the yield coefficients of both biomass and lipids production, but had positive effect on the growth rate and thus on volumetric productivity of lipid. In glucose-based media, cellular multiplication occurred first, while the lipogenic phase followed whenever the culture was limited by a nutrient other than glucose. The extent of the carbon excess had positive effects on triacylglycerols production, that was maximum with 120 g L^-1glucose, in terms of lipid concentration (19 g L^-1), lipid/biomass (68%) and lipid/glucose yields (16%). Both glucose concentration and growth temperature influenced the composition of fatty acids, whose unsaturation degree decreased when the temperature or glucose excess increased.</p> <p>Conclusions</p> <p>This study is the first proposed biotechnological application for <it>Rhodotorula glacialis </it>species, whose oleaginous biomass accumulates high amounts of lipids within a wide range of temperatures through appropriate cultivation C:N ratio. Although <it>R. glacialis </it>DBVPG 4785 is a cold adapted yeast, lipid production occurs over a broad range of temperatures and it can be considered an interesting microorganism for the production of single cell oils.</p

Strain sensing on steel surfaces using vacuum packaged MEMS resonators

The paper presents a technology for strain sensing on steel using resonant MEMS packaged in vacuum. For this purpose, a custom sensor fabrication technology and a novel vacuum packaging technique have been developed. The MEMS sensors have been fabricated by surface micromachining of thick (15 μm) Silicon On Insulator substrates with heavily doped handle layers View the MathML source(ρ = 0.005 Ωcm). Using this process, Double-Ended Tuning Fork (DETF) parallel-plate resonators with reduced coupling gaps (less than 1 μm) have been fabricated, using a high-performance Deep Reactive Ion Etching performed on submicrometer features realized by near-UV lithography combined with a maskless line narrowing technique. The devices have been bonded to a thin steel bar by epoxy glue, packaged in vacuum and tested by applying strain to the bar, showing good tolerances to packaging parasitics, measurement reversibility, and strain sensitivity of View the MathML source10Hz/με

High-resolution strain sensing on steel by Silicon-On-Insulator flexural resonators fabricated with chip-level vacuum packaging

This paper reports on the fabrication and characterization of high-resolution strain sensors for steel based on Silicon On Insulator flexural resonators manufactured with chip-level LPCVD vacuum packaging. The sensors present high sensitivity (120 Hz/??), very high resolution (4 n?), low drift, and near-perfect reversibility in bending tests performed in both tensile and compressive strain regimes

Conservation Medicine: a STS approach to environmental, food and health education

En la actualidad, han surgido numerosos campos del conocimiento relacionados a la problemática ambiental, alimentaria y de salud, producto de la interacción humana con el ambiente. A través del conocimiento de estas áreas, pueden abordarse temáticas que permiten una comprensión de aspectos de la Ciencia, la Tecnología y la Sociedad. En este trabajo, se presenta una aplicación educativa denominada “Medicina de la Conservación” (MdlC), una disciplina que engloba, bajo una única salud, a la salud animal, humana y del ambiente. En el presente artículo se emplea la MdlC como herramienta educativa para incorporar contenidos CTS dentro del área de las ciencias naturales y, además, fomentar el Pensamiento Crítico. Se desarrolla una Unidad Didáctica, UD aplicada a tres grupos: uno de nivel medio de una escuela agropecuaria, otro de formación del profesorado y por último, un grupo de estudiantes de ingeniería en alimentos. La UD incluyó el abordaje de las Enfermedades Transmitidas por Alimentos (ETA) y las zoonosis en diferentes espacios como la granja de la escuela, los zoológicos, los bioparques y los parques nacionales. Para la evaluación de la UD, se utilizó un cuestionario y el formato de entrevista del proyecto: Educación de las competencias científica, tecnológica y pensamiento crítico mediante la enseñanza de temas de naturaleza de ciencia y tecnología (CYTPENCRI). De los resultados se destacan el interés, la motivación y el desarrollo de toma de decisiones por parte del estudiantado frente a las zoonosis y ETA a partir del abordaje desde la MdlC.Currently, numerous fields of knowledge have emerged related to environmental, food and health problems, as a result of human interaction with the environment. Through knowledge of these areas, topics that allow an understanding of aspects of Science, Technology and Society can be addressed. In this work, an educational application called “Conservation Medicine” (CM) is presented, a discipline that encompasses, under a single health, animal, human and environmental health. In this article, the CM is used as an educational tool to incorporate CTS content within the natural sciences area and, in addition, to promote Critical Thinking. A Didactic Unit is developed, DU applied to three groups: one of medium level of an agricultural school, another of teacher training and finally, a group of students of food engineering. The DU included the approach of Foodborne Diseases (FD) and zoonoses in different spaces such as the school farm, zoos, bioparks and national parks. For the evaluation of the DU, a questionnaire and the interview format of the project were used: Education of scientific, technological and critical thinking skills through the teaching of subjects of a science and technology nature (CYTPENCRI). The results highlight the interest, motivation and the development of decision-making by the students against zoonoses and FD from the approach from the CM.Atualmente, surgiram inúmeras áreas do conhecimento relacionadas a problemas ambientais, alimentares e de saúde, como resultado da interação humana com o meio ambiente. Através do conhecimento dessas áreas, podem ser abordados tópicos que permitem o entendimento entre os aspectos da Ciência, Tecnologia e Sociedade. Neste trabalho, é apresentada uma aplicação educacional denominada “Medicina de Conservação” (MdC), disciplina que engloba, sob uma única saúde, saúde animal, humana e ambiental. Neste artigo, o MdC é usado como uma ferramenta educacional para incorporar o conteúdo da CTS na área de ciências naturais e, além disso, para promover o Pensamento Crítico. É desenvolvida uma Unidade Didática (UD), aplicada a três grupos: um de nível médio de uma escola agrícola, outro de formação de professores e, finalmente, um grupo de estudantes de engenharia de alimentos. A UD incluiu a abordagem de Doenças Transmitidas por Alimentos (DTA) e zoonoses em diferentes espaços, como a fazenda da escola, zoológicos, bioparques e parques nacionais. Para a avaliação da UD, utilizou-se um questionário e o formato de entrevista do projeto: Educação de habilidades de pensamento científico, tecnológico e crítico por meio do ensino de disciplinas de natureza científica e tecnológica (CYTPENCRI). Os resultados destacam o interesse, a motivação e o desenvolvimento da tomada de decisões dos estudantes contra zoonoses e DTA a partir da abordagem do MdC.Fil: Lampert, Damian Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; ArgentinaFil: Russo, Matias. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias; Argentina. Universidad Nacional de Quilmes; ArgentinaFil: Scandroglio, Natalia. No especifíca;Fil: Roncaglia, Diana Inés. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentin

Fabrication and testing of a high resolution extensometer based on resonant MEMS strain sensors

A novel type of linear extensometer with exceptionally high resolution of 4 nm based on MEMS resonant strain sensors bonded on steel and operating in a vacuum package is presented. The tool is implemented by means of a steel thin bar that can be pre-stressed in tension within two fixing anchors. The extension of the bar is detected by using two vacuum-packaged resonant MEMS double-ended tuning fork (DETF) sensors bonded on the bar with epoxy glue, one of which is utilized for temperature compensation. Both sensors are driven by a closed loop self-oscillating transresistance amplifier feedback scheme implemented on a PCB (Printed Circuit Board). On the same board, a microcontroller-based frequency measurement circuit is also implemented, which is able to count the square wave fronts of the MEMS oscillator output with a resolution of 20 nsec. The system provides a frequency noise of 0.2 Hz corresponding to an extension resolution of 4 nm for the extensometer. Nearly perfect temperature compensation of the frequency output is achieved in the temperature range 20-35°C using the reference sensor

Design and prototyping of a MEMS-based crackmeter for structural monitoring

Crack measurement is an important technique in structural monitoring, which is presently implemented with macroscopic devices characterized by rather demanding power consumption requirements. Such devices, consequently, are not very well suited for wireless operation, which is particularly interesting for specific applications involving deployment of a number of crackmeters within large-scale ageing infrastructures with possibility of remote, on-demand sensor interrogation. This paper reports about the research work related to the design and prototyping of a novel crackmeter suited for wireless structural monitoring realized with silicon MEMS strain sensors with high resolution, very low power operation and small size