Thermal shock resistance of mullite/Sr-celsian/zirconia composites

Rodríguez-Salazar P.,Almanza-Robles J. M.,Cortés-Hernández D. A.,Escobedo-Bocardo J. C. 한국세라믹학회 2022 한국세라믹학회지 Vol.59 No.6

The thermal shock resistance of novel mullite /Sr-celsian /zirconia composites was studied. The eff ect of the Sr-celsian (15, 20, 25 wt.%) and ZrO 2 (5, 15, 25 wt.%) amounts on the thermal shock resistance, was evaluated. The composites were obtained at 1450 °C. Thermal shock resistance was performed by heating samples up to a selected temperature (∆ T = 200–1000 °C) and then suddenly immersed in water. After testing, the bending strength was evaluated and the results were statistically analyzed using Minitab with a confi dence level of 0.05. Pareto charts showed that Sr-celsian and zirconia content have the highest infl uence on fl exural strength after thermal shock. The highest thermal shock resistance was obtained for the composites with the highest amount of zirconia and Sr-celsian. Most of the composites showed a decrease in strength of around 75%. The strength of the composites with 20 or 25 wt.% of celsian and 25 wt.% zirconia increased at ∆ T of 1000 °C. The Pareto chart for these composites showed that zirconia has the highest eff ect on strength. A change in expansion is shown between 800 and 900 °C, indicating the transformation of monoclinic to tetragonal zirconia. This transformation generates microc- racks that defl ect cracks generated during thermal stress. Also, residual stresses are generated during cooling which plays a role in absorbing the energy of a generated crack. The strontium celsian forms an interlocked microstructure that improves strength. These composites are promising materials for applications in which sudden and extreme temperature changes occur.

Blood-brain Barrier Damage is Pivotal for SARS-CoV-2 Infection to the Central Nervous System

Rodríguez-Morales Jahir,Guartazaca-Guerrero Sebastián,Rizo-Téllez Salma A.,Viurcos-Sanabria Rebeca,Barrón Eira Valeria,Hernández-Valencia Aldo F.,Nava Porfirio,Escobedo Galileo,Carrillo-Ruiz José Dami 한국뇌신경과학회 2022 Experimental Neurobiology Vol.31 No.4

Transsynaptic transport is the most accepted proposal to explain the SARS-CoV-2 infection of the CNS. Nevertheless, emerging evidence shows that neurons do not express the SARS-CoV-2 receptor ACE2, which highlights the importance of the blood-brain barrier (BBB) in preventing virus entry to the brain. In this study, we examine the presence of SARS-CoV-2 messenger ribonucleic acid (mRNA) and the cytokine profile in cerebrospinal fluids (CSF) from two patients with a brain tumor and COVID-19. To determine the BBB damage, we evaluate the Q- albumin index, which is an indirect parameter to assess the permeability of this structure. The Q-albumin index of the patient with an intraventricular brain tumor suggests that the BBB is undamaged, preventing the passage of SARS-CoV-2 and pro-inflammatory molecules. The development of brain tumors that disrupt the BBB (measured by the Q-albumin index), in this case, a petroclival meningioma (Case 1), allows the free passage of the SARS-CoV-2 virus and probably lets the free transit of pro-inflammatory molecules to the CNS, which leads to a possible activation of the microglia (astrogliosis) and an exacerbated immune response represented by IL-13, IFN-γ, and IL-2 trying to inhibit both the infection and the carcinogenic process.

<i>δ</i> Sct-type pulsations in eclipsing binary systems: Y Cam

Rodrí,guez, E.,Garcí,a, J. M.,Costa, V.,Lampens, P.,van Cauteren, P.,Mkrtichian, D. E.,Olson, E. C.,Amado, P. J.,Daszyń,ska-Daszkiewicz, J.,Turcu, V.,Kim, S.-L.,Zhou, A. Y.,Ló,p Blackwell Publishing Ltd 2010 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.408 No.4

<P>ABSTRACT</P><P>We present the results of a three-continent multisite photometric campaign carried out on the Algol-type eclipsing binary system Y Cam, in which the primary component is a multiperiodic δ Sct-type pulsator. The observations consist of 86 nights and more than 450 h of useful data collected mainly during the Northern winter 2002–2003. This means that this is the most extensive time series for such kind of systems obtained so far. These observations were collected mostly in the Johnson V filter, but they also include, for the first time, nearly complete binary light curves in simultaneous Strömgren <I>uvby</I> filters together with a few Crawford Hβ data obtained around the orbital phase of the first quadrature. A detailed photometric analysis is presented for both binarity and pulsation. The results indicate a semidetached system with the secondary filling its Roche lobe. No significant contribution from a third body is found. The residuals from the computed binary solution were then used to investigate the pulsational content of the primary component. The frequency analysis of the out-of-primary-eclipse data leads to a set of eight significant and independent pulsational peaks in a well-defined region of the frequency domain. This means that this is the largest set of excited modes discovered so far in the pulsating component of such kind of systems. The possibility of aliasing problems during the present run or short-term time-scale amplitude variations in some of them was investigated with null results. Indeed the results indicate that <I>f</I><SUB>1</SUB> and <I>f</I><SUB>3</SUB> form a frequency doublet with a beat period of <I>P</I><SUB>beat</SUB>= 17.065 d. Our results confirm the frequencies already detected by earlier authors and show the presence of some additional significant peaks. The observed amplitudes during the present run are also consistent with those derived from older data sets. We perform a preliminary mode identification for most of the frequencies on the basis of the collected multicolour photometry, the observed frequency spacings and the mode visibility in eclipsing binaries.</P>

The medium-term consequences of COVID-19 lockdown on lifestyle among Spanish older people with hypertension, pulmonary, cardiovascular, and musculoskeletal-diseases, depression, and cancer

Rodríguez-Gómez Irene,Sánchez-Martín Coral,García-García Francisco J.,García-Esquinas Esther,Miret Marta,Vicente-Rodriguez Germán,Gusi Narcís,Mañas Asier,Carnicero José A.,Gonzalez-Gross Marcela,Ayuso 한국역학회 2022 Epidemiology and Health Vol.44 No.-

OBJECTIVES: This study investigated the associations of chronic diseases with changes in lifestyle and health behaviours in older people following the coronavirus disease 2019 (COVID-19) lockdown in Spain and compared the differences in changes over time. METHODS: 1,092 participants (80.3± 5.6 years; 66.5% female) from 2 Spanish cohorts were included. Telephone-based questionnaires were conducted to evaluate lifestyle and health risk behaviours at the end of lockdown and 7 months post-lockdown. Participants were classified as having physician-diagnosed chronic diseases based on self-reported data. Cox proportional models adjusted for major confounders were used. RESULTS: Compared to those without the corresponding chronic diseases, older people with hypertension were less likely to report increased alcohol consumption (hazard ratio [HR], 0.73; 95% confidence interval [CI], 0.55 to 0.99). Pulmonary diseases were associated with lower risks of increased sedentary time (HR, 0.58; 95% CI, 0.39 to 0.86) and worsened sleep quality (HR, 0.56; 95% CI, 0.36 to 0.87), while cardiovascular diseases were associated with a lower risk of decreased sedentary time (HR, 0.58; 95% CI, 0.38 to 0.88). Depression was linked to a higher likelihood of improved diet quality (HR, 1.53; 95% CI, 1.00 to 2.36). Cancer pacients were less likely to have worsened sleep quality (HR, 0.44; 95% CI, 0.22 to 0.89) but more likely to have reduced their frequency of social contact (HR, 2.05; 95% CI, 1.05 to 3.99). CONCLUSIONS: Older people with chronic diseases showed beneficial changes in lifestyle and health risk behaviours after the COVID-19 lockdown. In particular, older people with hypertension, pulmonary disease, and cancer tended to make beneficial lifestyle and health behaviour changes. However, older people with cardiovascular disease and depression engaged in more health risk behaviours.

Response to rearing in laboratory of the xylophagous grape pest, Xylotrechus arvicola (Coleoptera: Cerambycidae)

Álvaro Rodríguez‐González,Sara MAYO,Óscar GONZÁLEZ-LÓPEZ,Horacio J. PELÁEZ,Pedro A. CASQUERO 한국곤충학회 2017 Entomological Research Vol.47 No.4

Xylotrechus arvicola (Olivier) (Coleoptera: Cerambycidae) is an important pest in vineyards (Vitis vinifera) in the main Iberian wine‐producing regions. Larvae were reared with Semi‐Synthetic Iglesias (SSI) diet over 27 months and two generations in the laboratory. Larval mortality was highest during the first (49.49 %) and second (9.38 %) month of rearing, increasing to 50.52 % during the first month if F2 reared larvae were obtained from an F1 adult female obtained in laboratory. The diet had sufficient nutrients to enable the pest to complete its life cycle within nine months, with F1 larval viability ranging from 23.49 % to 27.97 % and F2 larval viability reduced to 2.07 %. However, the diet did not allow for the completion of additional life cycles and generations (F3, F4,…). Larval mortality increased as the months of rearing (66.13 %, 69.51 % and 89.50 %) and generations (59.10 % and 76.93 % in F1 and F2, respectively) progressed in the laboratory. The larva–adult period of females obtained in the laboratory was longer than for males. In the laboratory, the life cycle was shortened in relation to the life cycle in the field because larvae did not require a cold period to break diapause and start pupation. This indicates that X. arvicola has the potential to complete its life cycle inside grape wood in vineyards of wine‐producing regions with warmer winters.

Short-, Intermediate-, and Long-Term Changes in Basophil Reactivity Induced by Venom Immunotherapy

Ana Rodríguez Trabado,Carmen Cámara Hijón,Alfonso Ramos Cantariño,Silvia Romero-Chala,José Antonio García-Trujillo,Luis Miguel Fernández Pereira 대한천식알레르기학회 2016 Allergy, Asthma & Immunology Research Vol.8 No.5

Purpose: The basophil activation test (BAT) has been used to monitor venom immunotherapy (VIT) due to its high specificity. A previous study has reported a good correlation between a significant decrease in basophil activation during 5 years of VIT and clinical protection assessed by sting challenge. The following prospective study was performed to examine changes in basophil reactivity over a complete VIT period of 5 years. Methods: BAT in a dose-response curve was studied prospectively in 10 hymenoptera venom-allergic patients over 5 years of VIT. BAT was performed at the time of diagnosis, 1 month after finishing the VIT build-up phase, and 3, 6, 12, 24, and 60 months after beginning treatment. The repeated measures ANOVA was applied to evaluate basophil activation changes throughout VIT. A cross-sectional study was also performed in 6 patients who received treatment for more than 3 years, and in another 12 patients who followed immunotherapy for at least 5 years. Results: An early activation decrease was observed during the first 3 months of treatment, compared to pre-treatment values. This activation decrease was not maintained 6 to 18 months after treatment, but was observed again after 2 years of treatment, and maintained until the completion of the 5-year immunotherapy period. In cross-sectional analysis, the 6 patients who received treatment for 3 years, and 9 of the 12 patients who received treatment for 5 years, had negative BAT results. Three patients in this last group had positive BAT results and 2 patients had systemic reactions after field stings. Conclusions: BAT appears to be an optimal non-invasive test for close monitoring of VIT.

Silver nanoparticles incorporated into Na₂Ti6O13 microfibers

V. Rodríguez-González,I. Juárez-Ramírez,R. Zanella,M.E. Zarazúa,L.M. Torres-Martínez 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.6

This research is concerned with novel semiconductor composites of sodium hexatitanate oxide (Na2Ti6O13), and silver metallic nanoparticles. The Na2Ti6O13 was prepared by two methods, a sol-gel process and a solid state reaction. The silver nanoparticles were incorporated into the titanate by a deposition-precipitation technique, using NaOH as precipitation agent in the dark. Ag/Na2Ti6O13 microfibers were obtained by the sol-gel method, meanwhile octagonal microbar agglomerates were the product of the solid state reaction. The SEM-TEM observations showed silver particles with a nanometric size (5-7 nm); and fibrillar structures in the sol-gel sodium titanates. The UV-Vis-RD spectroscopy showed a blue shift Eg from 3.3 to 3.4 nm; and a plasmon surface resonance in the visible region. These materials are proposed as potential photocatalysts for contaminated water purification. This research is concerned with novel semiconductor composites of sodium hexatitanate oxide (Na2Ti6O13), and silver metallic nanoparticles. The Na2Ti6O13 was prepared by two methods, a sol-gel process and a solid state reaction. The silver nanoparticles were incorporated into the titanate by a deposition-precipitation technique, using NaOH as precipitation agent in the dark. Ag/Na2Ti6O13 microfibers were obtained by the sol-gel method, meanwhile octagonal microbar agglomerates were the product of the solid state reaction. The SEM-TEM observations showed silver particles with a nanometric size (5-7 nm); and fibrillar structures in the sol-gel sodium titanates. The UV-Vis-RD spectroscopy showed a blue shift Eg from 3.3 to 3.4 nm; and a plasmon surface resonance in the visible region. These materials are proposed as potential photocatalysts for contaminated water purification.

Grain Boundaries and Phases Identification of Metallographic Images by a Normalized Sobel Operation and the Edge Thinning Process for Further Numerical Simulation

G. Domínguez‑Rodríguez,J. A. González‑Sánchez,J. Rosado‑Carrasco,G. Canto 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.9

The recognitions of phases and precise grain boundaries based on metallographic images are useful for conducting micromechanicalsimulations, such as finite element analysis and peridynamics. In this work, those processes are automatized byusing a Sobel operator for identifying edges, which is normalized by different proposed Gaussian filters (on intensity, rugosity,or both). After that, a threshold is used to discretize the edges. Different neighboring pixel configurations, sensitive to edgeintensity, are proposed for thinning and cleaning the discretized edges, and hence, grain boundaries with a one-pixel thicknessare obtained. Then, the phase is selected by averaging color of each delimited grain. Finally, the precision on the phaserecognition was found to increase from 75.61 to 83.6% for the unmodified and the normalized Sobel operator, respectively.

Effects of adults body size and larvae diet on the fecundity and percent fertility of eggs laid by Xylotrechus arvicola (Coleoptera: Cerambycidae) females, insect pest in Spanish vineyards

Álvaro Rodríguez‐González,Horacio J. PELÁEZ,Óscar GONZÁLEZ-LÓPEZ,Sara MAYO,Pedro A. CASQUERO 한국곤충학회 2018 Entomological Research Vol.48 No.2

Xylotrechus arvicola is a pest of grape in some vine‐producing regions of the Iberian Peninsula. Biological parameters and relationships (fecundity and percent fertility of eggs in relationship to body size) of females obtained in the laboratory and captured in vineyards were studied. In laboratory conditions, the mean developmental time of larvae ranged from 384 to 392 days and pupal stage varied between 12 to 14 days. Body size (BS) of X. arvicola females was significantly bigger than males. Fecundity was greater in the laboratory (147 eggs) than in the field (50 eggs) females, but the percent fertility of the laboratory eggs was lower (16 eggs). Laboratory females showed a bigger relationship between the production of eggs and BS than females captured in vineyards. Wild females (PDO Ribera del Duero and Tierra de León) had a positive relationship between the percent fertility of eggs and the BS. No correlation between the percent fertility of eggs and the BS was displayed by females captured in PDO Toro, but these females had a higher percent fertility (53 eggs) than the others PDO's. These biological parameters and relationships studied suggest that the artificial diet may lack certain essential nutrients that vine varieties can provide that favor the fertility of eggs. This explains why wild females have the potential to become a problem pest in the Tempranillo grape variety, with bilateral cordon and bush vines training systems that have the highest incidence of this cerambycid.

Chitosan-Hydroxyapatite Scaffold for Tissue Engineering in Experimental Lumbar Laminectomy and Posterolateral Spinal Fusion in Wistar Rats

Martin Rodríguez-Vázquez,Rodrigo Ramos-Zúñiga 대한척추외과학회 2020 Asian Spine Journal Vol.14 No.2

Study Design: Experimental study with an animal model. Purpose: To evaluate the role of a chitosan and hydroxyapatite composite for spinal fusion in a lumbar experimental model based on regenerative tissue engineering principles. Overview of Literature: Chitosan and hydroxyapatite represent an alternative biodegradable implant material for tissue engineering and regeneration. The combination of chitosan and hydroxyapatite in a 20:80 ratio could potentiate their individual properties as an implantable composite for experimental laminectomy. Methods: Phase I: design and synthesis of a porous composite scaffold composed of chitosan-hydroxyapatite using a freeze drying technique. Phase II: experimental microsurgical lumbar laminectomy at L5. A total of 35 Wistar rats were categorized into three experimental groups: control (laminectomy alone), experimental (laminectomy with implant), and reference (intact spine) (n=5 per group). Postoperative structural and functional evaluations were performed using computed tomography scans. In addition, radiologic, clinical, histological, and immunohistochemical microstructures were evaluated. Results: At the laminectomy site, the composite implant induced bone regeneration, which was observed in the axial reconstruction of the rat lumbar spine in all cases. Biomechanical changes in the lumbar spine were observed by radiology in both groups after the surgery. The posterolateral space was covered by a bone structure in the treated spine, a condition not seen in the control group. The range of motion was 7.662°±0.81° in the scaffold group versus 20.72°±3.47° in the control group. Histological findings revealed qualitatively more bone tissue formation in the implant group. Conclusions: A composite of chitosan-hydroxyapatite at a 20:80 ratio induced bone formation after experimental laminectomy in rats and led to spinal fusion, which was assessed by radiology and biomechanical tests. No functional complications in posture or walking were observed at 90 days post-surgery, despite biomechanical changes in the spine.