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Influence of Graphene Nanosheets on Thermo-Physical and Tribological Properties of Sustainable Cutting Fluids for MQL Application in Machining Processes
Get PDFThe growing need to increase productivity and pressures for more sustainable manufacturing processes lead to a shift to less harmful lubrication systems that are less harmful to nature and the
people involved. The minimal quantity lubrication system (MQL) stands out in this respect, especially
in interrupted cutting processes such as milling, due to the cutting interface’s highly dynamic and
chaotic nature. Using graphene sheets in cutting fluids also increases the efficiency of machining
processes. This work investigates the influence on thermophysical and tribological properties of
concentrations of 0.05 wt% and 0.1 wt% of graphene sheets in two vegetable-based and one mineralbased cutting fluids. The fluids are first characterized (viscosity, thermal conductivity, diffusivity, and
wettability) and tested in reciprocating and ramp milling tests; all experiments are based on norms.
The results show that the experiments with cutting fluids (with and without graphene) showed better
tribological behavior than those in dry conditions. The graphene sheets alter the thermo-physical
and tribological properties of the cutting fluids. The MQL15 vegetable-based fluid showed better
lubricating properties in the milling tests, with better conditions for tribosystem chip–tool–workpiece
interfaces, which makes the friction coefficient, and wear rate stable. Vegetable-based cutting fluids,
even in minimum quantities and with graphene nanoparticles, have a high potential for increasing
the efficiency and sustainability of the milling process.This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES)—Finance Code 001 and CNPq
Images of the sacred in the painting of Juan de Flandes
Get PDFUna mirada atenta a la pintura de Juan de Flandes, del que sólo se conoce su actividad en España,
revela la pervivencia de muchos recursos expresivos de su procedencia flamenca, aunque no
transcritos de forma literal, sino pasados por el tamiz de su sensibilidad. En sus figuraciones de
paisajes, arquitecturas, ambientes y personajes añadió su propia interpretación sobre la condición moral de todos ellos. Lo patético, lo bello, lo grotesco y lo poético tuvieron su lugar en una
narración religiosa teatralizada, que se presentaba transcendida y a un tiempo cercana a los ojos
del espectador.An attentive look at the painting of Juan de Flandes, who is only known to have worked in
Spain, reveals the survival of many expressive resources of his Flemish origin, although not
transcribed literally, but passed through the nuance of his sensitivity. In his figurations of
landscapes, architectures, environments and characters, he added his own interpretation of the
moral condition of all of them. The pathetic, the beautiful, the grotesque and the poetic had their
place in a dramatized religious narrative, which was transcended and at a time close to the eyes
of the viewer.Este estudio se ha hecho en el marco del GIR “IDINTAR. Identidad e intercambios artísticos de la Edad Media al Mundo Contemporáneo”, de la Universidad de Valladolid
Glass-box modeling for quality assessment of resistance spot welding joints in industrial applications
No full textResistance spot welding (RSW) is one of the most relevant industrial processes in diferent sectors. Key issues in RSW are
process control and ex-ante and ex-post evaluation of the quality level of RSW joints. Multiple-input–single-output methods
are commonly used to create predictive models of the process from the welding parameters. However, until now, the choice
of a particular model has typically involved a tradeof between accuracy and interpretability. In this work, such dichotomy
is overcome by using the explainable boosting machine algorithm, which obtains accuracy levels in both classifcation and
prediction of the welded joint tensile shear load bearing capacity statistically as good or even better than the best algorithms
in the literature, while maintaining high levels of interpretability. These characteristics allow (i) a simple diagnosis of the
overall behavior of the process, and, for each individual prediction, (ii) the attribution to each of the control variables—and/
or to their potential interactions—of the result obtained. These distinctive characteristics have important implications for
the optimization and control of welding processes, establishing the explainable boosting machine as one of the reference
algorithms for their modeling.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. The authors acknowledge fnancial support from the Spanish Ministry of Science, Innovation and Universities (Excellence Network RED2018‐102518‐T), the Spanish State Research Agency (PID2020-118906 GB-I00/AEI/https://doi.org/10. 13039/501100011033), and the Fundación Bancaria Caixa D. Estalvis I Pensions de Barcelona, La Caixa (2020/00062/001). In addition, we acknowledge support from the Santander Supercomputación group (University of Cantabria) that provided access to the Altamira Supercomputer—located at the Institute of Physics of Cantabria (IFCACSIC) and member of the Spanish Supercomputing Network—to perform the diferent simulations/analyses
New Technique for Probing the Protecting Character of the Solid Electrolyte Interphase as a Critical but Elusive Property for Pursuing Long Cycle Life Lithium-Ion Batteries
Get PDFThe formation of a protecting nanolayer, so-called solid
electrolyte interphase (SEI), on the negative electrode of Li-ion batteries
(LIBs) from product precipitation of the cathodic decomposition of the
electrolyte is a blessing since the electrically insulating nature of this
nanolayer protects the electrode surface, preventing continuous electrolyte decomposition and enabling the large nominal cell voltage of LIBs,
e.g., 3.3−3.8 V. Thus, the protection performance of the nanolayer SEI is
essential for LIBs to achieve a long cycle life. Unfortunately, the
evaluation of this critical property of the SEI is not trivial. Herein, a new,
cheap, and easily implementable methodology, the redox-mediated
enhanced coulometry, is presented to estimate the protecting quality of
the SEI. The key element of the methodology is the addition of a redox
mediator in the electrolyte during the degassing step (after the SEI
formation cycle). The redox mediator leads to an internal self-discharge process that is inversely proportional to the protecting
character of the SEI. Also, the self-discharge process results in an easily measurable decrease in Coulombic efficiency. The influence
of vinylene carbonate as an electrolyte additive in the resulting SEI is used as a case study to showcase the potential of the proposed
methodology.The author acknowledges the financial support from the Spanish Government (MINECO) through the Research Challenges Programme (Grant RTI2018-099228-A-I00) and Ramón y Cajal award (RYC2018-026086-I) as well as the NanoBat project. NanoBat has received funding from the European Union’s Horizon 2020 research and innovation program under Grant Agreement no. 861962
Asymmetric Gold(I)‐Catalyzed Tandem Hydroarylation–Nazarov Cyclization: Enantioselective Access to Cyclopentenones
Get PDFThe asymmetric synthesis of cyclopentachromenones from gold-catalyzed reaction of readily available skipped alkenynones is described. This cascade
reaction involves an initial anti-Michael hydroarylation
of the ynone moiety to form a gold-functionalized
dialkenylketone intermediate, followed by a Nazarov
cyclization that proceeds in an unprecedented enantioselective manner. Excellent enantiomeric ratios and chemical yields are obtained under mild reaction conditions.We gratefully acknowledge Ministerio de Ciencia e Innovación and FEDER (CTQ2016-75023-C2-1-P and PID2020- 115789GB-C21), and Junta de Castilla y León and FEDER (BU291P18 and BU049P20) for financial support. The project leading to these results has received funding from “la Caixa” Foundation, under the Agreement LCF/PR/ PR18/51130007> (CAIXA-UBU001). M.S. and S.S.-P. thank Junta de Castilla y León (Consejería de Educación) and Fondo Social Europeo (ESF+) for a predoctoral and a postdoctoral contract, respectively
Modul III. 5. Poremećaji ranog djetinjstva: poremećaji iz spektra autizma
Get PDFA lo largo de este módulo III.5 nos hemos ido adentrando en la realidad de los Trastornos del Espectro del Autismo (TEA). Se ha abordado la definición, historia, características nucleares, etiología, teorías explicativas y prevalencia. Se ha resaltado que la detección y atención tempranas constituyen una necesidad primordial para mejorar la calidad de vida de las personas que, en su condición de TEA, presentan un estilo cognitivo diferente, un ritmo de aprendizaje distinto, dado que su cerebro procesa la información de otra manera. Se han mostrado herramientas (pruebas de evaluación, programas de intervención) dirigidas a conseguir este objetivo.Throughout this module III. 5 we have been getting into the reality of the Autism
Spectrum Disorders (ASD). The definition, history, core characteristics, aetiology,
explanatory theories and prevalence have been approached. It has been highlighted
that early detection and attention constitute a primordial need to improve the quality
of life of people who, in their condition of ASD, present a different cognitive style, a
different learning rhythm, given that their brain processes information in a different
way. Tools (assessment tests, intervention programmes) aimed at achieving this goal
have been demonstrated.Nel corso di questo modulo III.4 abbiamo analizzato la realtà dei disturbi dello spettro
autistico (ASD). Abbiamo affrontato la definizione, la storia, le caratteristiche principali,
l'eziologia, le teorie esplicative e la prevalenza. Abbiamo visto che la diagnosi precoce e
l'attenzione sono un'esigenza fondamentale per migliorare la qualità della vita di persone
che, a causa della loro condizione di ASD, presentano stili cognitivi diversi e ritmi di
apprendimento differenti, dato che il loro cervello elabora le informazioni in modo
diverso. Sono stati esaminati gli strumenti (test di valutazione, programmi di intervento)
per raggiungere questo obiettivo.Kroz modul III.5 detaljno je prikazan i objašnjen poremećaj iz spektra autizma (ASD). Obrađene su definicija, povijest, temeljne karakteristike, etiologija, teorije objašnjenja i prevalencija. Naglašeno je da su rano otkrivanje i skrb ključni za poboljšanje kvalitete života ljudi koji, u svom stanju ASD-a, imaju drugačiji kognitivni stil, drugačiji ritam učenja, budući da njihov mozak obrađuje informacije na drugi način. Prikazani su alati (testovi procjene, intervencijski programi) usmjereni na postizanje ovog cilja.“Specialized and updated training on supporting advance technologies for early childhood education and care professionals and graduates”, eEarlyCare-T, reference 2021-1-ES01-KA220-SCH-000032661, is co-financed by the European Union's Erasmus+ programme, line KA220 Strategic Partnerships Scholar associations
Performance and Extreme Conditions Analysis Based on Iterative Modelling Algorithm for Multi-Trailer AGVs
Get PDFAutomatic guidance vehicles (AGV) are industrial vehicles that play an important role in
the development of smart manufacturing systems and Industry 4.0. To provide these autonomous
systems with the flexibility that is required today in these industrial workspaces, AGV computational
models are necessary in order to analyze their performance and design efficient planning and control
strategies. To address these issues, in this work, the mathematical model and the algorithm that
implement a computational control-oriented simulation model of a hybrid tricycle-differential AGV
with multi-trailers have been developed. Physical factors, such as wheel-ground interaction and the
effect of vertical and lateral loads on its dynamics, have been incorporated into the model. The model
has been tested in simulation with two different controllers and three trajectories: a circumference,
a square, and an s-shaped curve. Furthermore, it has been used to analyze extreme situations of
slipping and capsizing and the influence of the number of trailers on the tracking error and the
control effort. This way, the minimum lateral friction coefficient to avoid slipping and the minimum
ratio between the lateral and height displacement of the center of gravity to avoid capsizing have
been obtained. In addition, the effect of a change in the friction coefficient has also been simulated
Quality of Life in Breast Cancer Survivors in Relation to Age, Type of Surgery and Length of Time since First Treatment
Get PDFQuality of life assessment is a critical aspect of breast cancer patient
outcomes, as diagnosis, prognosis and treatment can have a major impact on quality of life. The
aim of this study was to describe the characteristics of the sample and to verify the relationship
between quality of life (QOL) in women diagnosed with breast cancer (BC) and their age, type or
surgery and time since treatment
Nursing Students’ Perceived Satisfaction with Flipped Learning Experiences: A Mixed-Methods Study
Get PDFNowadays, technological teaching tools, such as virtual labs, have become essential,
especially in nursing degrees. These resources help implement practical learning based on selfregulation and it is important to know how satisfied students are with them. This means it is important
to study students’ perceived satisfaction with virtual labs in flipped learning experiences, which was
the general objective of the present study. The aims of the study were: (1) to determine whether there
were significant differences in nursing students’ perceived levels of satisfaction according to the type
of subject or gender; (2) to ascertain what strengths and weaknesses nursing students perceived about
using virtual labs; and (3) to determine the kinds of feelings (positive, negative or neutral) nursing
students had using virtual labs. A mixed research methodology was applied, with a sample of
222 undergraduate nursing students at Burgos University (Spain). There were significant differences
in the satisfaction perceived by students depending on the subject. Students reported medium-high
satisfaction with virtual labs, although they did note that digital skills are needed to use them and
suggested incorporating intelligent assistants. Virtual labs seem to be effective, although further
studies are needed.This work was supported by the Vice-Rectorate for Teaching Staff from University of Burgos (Spain) (grant numbers TVLab_01, 3/02/21) and the Ministry of Science and Innovation of Spain Projects I+D+i Research Challenges (grant number PID2020-117111RB-I00, 01/01/21)
Effects of Antioxidants on Pain Perception in Patients with Fibromyalgia—A Systematic Review
Get PDFIn recent years, antioxidant supplements have become popular to counteract the effects
of oxidative stress in fibromyalgia and one of its most distressing symptoms, pain. The aim of
this systematic review was to summarize the effects of antioxidant supplementation on pain levels
perceived by patients diagnosed with fibromyalgia. The words used respected the medical search
terms related to our objective including antioxidants, fibromyalgia, pain, and supplementation.
Seventeen relevant articles were identified within Medline (PubMed), Scopus, Web of Science (WOS),
the Cochrane Database of Systematic Review, and the Cochrane Central Register of Controlled Trials.
This review found that antioxidant supplementation is efficient in reducing pain in nine of the studies
reviewed. Studies with a duration of supplementation of at least 6 weeks showed a benefit on pain
perception in 80% of the patients included in these studies. The benefits shown by vitamins and
coenzyme Q10 are remarkable. Further research is needed to identify the effects of other types of
antioxidants, such as extra virgin olive oil and turmeric. More homogeneous interventions in terms
of antioxidant doses administered and duration would allow the effects on pain to be addressed more
comprehensively