A pH/Temperature-Sensitive s-IPN Based on Poly(vinyl alcohol), Poly(vinyl methyl ether-alt-maleic acid) and Poly(vinyl methyl ether) Prepared by Autoclaving

Karla F. García-Verdugo,Andya J. Ramírez-Irigoyen,Mónica Castillo-Ortega,Dora E. Rodríguez-Félix,Jesús M. Quiroz-Castillo,Judith Tánori-Córdova,Francisco Rodríguez-Félix,Antonio Ledezma-Pérez,Teresa d 한국고분자학회 2022 Macromolecular Research Vol.30 No.6

A novel semi-interpenetrating polymer network (s-IPN) based on the entrapment of a thermosensitive polymer, the poly(vinyl methyl ether) (PVME), within a crosslinked 3D structure of poly(vinyl alcohol) (PVA) and poly(vinyl methyl etheralt- maleic acid) (COP) was synthesized by an autoclaving process. The preparation method avoids the use of toxic crosslinkers and allows the simultaneous sterilization of material. The PVA/COP/PVME hydrogel were characterized by Fourier transform infrared spectroscopy, thermal techniques, swelling kinetic measurements, scanning electron microscopy, and rheological analysis. The entrapment of PVME within the hydrated polymer framework significantly modified its transition temperature at pH 7.4 and pH 3 conditions. The swelling kinetics of the s-IPN were dependent on pH (7.4, 3 and 1), and temperature (25 and 37℃). The interpenetrated polymer chains reduced the internal pore sizes of crosslinked network without altering its elastic, solid-like behavior. The loading and in vitro release of 5-fluorouracil, a chemotherapeutic agent, from hydrogel systems were studied at different temperature and pH values. The hydrogels showed a sustained drug release up to 5 h at 37℃, in different pH media. The s-IPN exhibited a promising performance for a range of biomedical applications, in particular, for the controlled drug delivery in response to the pH and temperature conditions.

A taxonomic and distributional study of the rhodolith-forming species Lithothamnion muelleri (Corallinales, Rhodophyta) in the Eastern Pacific Ocean

Néstor M. Robinson,G. I. Hansen,C. Fernández-García,R. Riosmena-Rodríguez 한국조류학회I 2013 ALGAE Vol.28 No.1

Lithothamnion muelleri is reported for the first time as one of the main components of rhodolith beds along the Eastern Pacific Ocean based on samples from Washington State (USA), Pacific Baja California (Mexico), southern Nicaragua, and Costa Rica. Individual rhodoliths ranged from fruticose to lumpy in morphology, and bi-sporangial, tetrasporangial, and gametangial plants were similar to those described from Australia and Brazil. Our study revealed a surprisingly wide latitudinal distribution of this species along the American continent. Its documentation in the Eastern Pacific will facilitate a more accurate interpretation of the ecology, biology, and biogeography of rhodolith beds worldwide.

New metal-free nanolubricants based on carbon-dots with outstanding antiwear performance

C. Chimeno-Trinchet,M.E. Pacheco,A. Fernández-González,M.E. Díaz-García,R. Badía-Laíño 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.87 No.-

Nanoparticles have already demonstrated a good performance in improving the wear and/or coefficientof friction when used as nanolubricants. Nevertheless, they show two main drawbacks: most of them aremetal-based and, therefore, eco-unfriendly, and they are mostly hydrophilic and, consequently, unstablein organic media, whichfinally drives to aggregation/sedimentation and the loose of the good properties. In this work, we carry out the synthesis of carbon-based nanoparticles for additives in lubricants fromtwo different approaches: either using ionic liquids as carbons source, or using glutathione as carbonsource and decorating the so-obtained carbon dots with the big organic cations of the ionic liquid. Thefinal materials (diameters between 2.2 and 3.5 nm) were characterized by TEM, FTIR, XPS, andluminescent methodologies,finding long-term stability of the suspensions in organic media ( 15 days). Carbon dots obtained directly from the ionic liquids, in particular from methyltrioctylammoniumchloride (MTOACDs) have demonstrated to be the best candidate as additive in different base oils (0.1%,w/v) and lubrication regimes, reducing the coefficient of friction about 30% and wear scar in more than60% in the most extreme of the tested conditions (120 N). Additionally, nanolubricants are metal-free andtherefore, more eco-friendly than classic additives.

Comparison of homogenization processes for the development of green O/W emulsions formulated with N,N-dimethyldecanamide

Luis A. Trujillo-Cayado,M. Carmen Alfaro,M.C. García,J. Muñoz 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.46 No.-

The target of this work was to compare the yield of three homogenization processes (two different rotor–stator devices and a high-pressure valve homogenizer) for the development of O(green solvent)/Wemulsions containing an eco-friendly emulsifier. Rheology, laser diffraction, optical microscopy andmultiple light scattering were the main techniques used to assess the efficiency of homogenizationmethods. First the best values of the processing variables were obtained for each homogenizer andsecondly a comparison of properties of emulsions prepared with these optimum processing conditionswas carried out. The results obtained revealed that the more stable emulsions were prepared with anUltraturrax T25.

Physical Properties of the Sr4Al6O12SO4 Ceramic Compound

J.A. Rodríguez-García,E. Rocha-Rangel,J. López Hernández,C.A. Hernández Bocanegra,A.L. Leal Cruz,J.M. Almanza Robles,J. Torres Torres 한양대학교 세라믹연구소 2017 Journal of Ceramic Processing Research Vol.18 No.11

The Sr4Al6O12SO4 ceramic compound was synthesized by a solid state reaction starting from stoichiometric mixtures of 3 : 3 : 1 molar ratio of reactive grade of SrCO3, Al2O3 and SrSO4, respectively. Cylindrical samples were confirmed by uniaxial pressing at 100 MPa and were heat treated at 1400 oC during 4 hrs. Subsequently, the samples were ground and re-conformed in cylindrical shape samples by uniaxial pressing at 300 MPa. The new samples were heat treated at 1400 oC during 24 hrs. This process was done in order to increase density of the samples. The Sr4Al6O12SO4 ceramic compound was characterized by the study of its physical properties such as: density, micro-hardness, thermal expansion and stability, enthalpy of formation, magnetic properties and electrical conductivity. Experimental results show that the maximum density obtained for the Sr4Al6O12SO4 ceramic compound was 2.913 grcm−3, with thermal expansion coefficient of 10.12E−06(oC−1); it also presents an enthalpy of 2.3 KJmol-1 and an excellent thermal stability at elevated temperatures in different atmospheres. In addition, the Sr4Al6O12SO4 ceramic compound is neither electrically conductive nor magnetic.

Role of TRPV4 Channel in Human White Adipocytes Metabolic Activity

Julio C. Sánchez,Aníbal Valencia-Vásquez,Andrés M. García 대한내분비학회 2021 Endocrinology and metabolism Vol.36 No.5

Background: Intracellular calcium (Ca2+) homeostasis plays an essential role in adipocyte metabolism and its alteration is associatedwith obesity and related disorders. Transient receptor potential vanilloid 4 (TRPV4) channels are an important Ca2+ pathway in adipocytes and their activity is regulated by metabolic mediators such as insulin. In this study, we evaluated the role of TRPV4 channelsin metabolic activity and adipokine secretion in human white adipocytes. Methods: Human white adipocytes were freshly cultured and the effects of the activation and inhibition of TRPV4 channels on lipolysis, glucose uptake, lactate production, and leptin and adiponectin secretion were evaluated. Results: Under basal and isoproterenol-stimulated conditions, TRPV4 activation by GSK1016709A decreased lipolysis whereasHC067047, an antagonist, increased lipolysis. The activation of TRPV4 resulted in increased glucose uptake and lactate productionunder both basal conditions and insulin-stimulated conditions; in contrast HC067047 decreased both parameters. Leptin productionwas increased, and adiponectin production was diminished by TRPV4 activation and its inhibition had the opposite effect. Conclusion: Our results suggested that TRPV4 channels are metabolic mediators involved in proadipogenic processes and glucosemetabolism in adipocyte biology. TRPV4 channels could be a potential pharmacological target to treat metabolic disorders.

Neural Mechanisms in Eating Behaviors: A Pilot fMRI Study of Emotional Processing

Rosa M. Molina-Ruiz,T. García-Saiz,Jeffrey C.L. Looi,E. Via Virgili,M. Rincón Zamorano,Laura de Anta Tejado,Helena Trebbau López,Jose Luis Carrasco Perera,Marina Díaz-Marsá 대한신경정신의학회 2020 PSYCHIATRY INVESTIGATION Vol.17 No.3

Objective Emotional processing dysfunction evident in eating disorders (ED) such as anorexia nervosa (AN) and bulimia nervosa (BN), is considered relevant to the development and maintenance of these disorders. The purpose of the current functional magnetic resonance imaging (fMRI) study was to pilot a comparison of the activity of the fronto-limbic and fronto-striatal brain areas during an emotion processing task in persons with ED. Methods 24 women patients with ED were scanned, while showing emotionally stimulating (pleasant, unpleasant) and neutral images from the International Affective Picture System (IAPS). Results During the pleasant condition, significant differences in Dorsolateral Prefrontal Cortex (DLPFC) activations were found with AN participants presenting greater activation compared to BN and ED comorbid groups (EDc) and healthy controls also showing greater activation of this brain area compared to BN and EDc. Left putamen was less activated in EDc compared to both controls (C) and AN. During the unpleasant condition, AN participants showed hyperactivation of the Orbito-Frontal Cortex (OFC) when compared to EDc. Conclusion This study highlights the potential functional relevance of brain areas that have been associated with self-control. These findings should help advance understanding the neural substrate of ED, though they should be considered as preliminary and be cautiously interpreted.

Validity of the Nielsen-type hanger arrangement in spatial arch bridges with straight decks

Mirian Cánovas-González,Juan M. García-Guerrero,Juan J. Jorquera-Lucerga 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.47 No.1

In tied-arch bridges, a properly designed connection between the arch and the deck may become crucial, since the forces in the structure may be significantly reduced. This implies substantial material savings and, consequently, cheaper constructions. The introduction of the Nielsen cable arrangement (composed of V-shaped inclined hangers) in the last century was a milestone because it was able to reduce deflections and bending moments both in the arch and in the deck. So far, the Nielsen cable arrangement has proven to be successful in traditional vertical arch bridges. However, despite its advantages, it has not been widely applied to spatial arch bridges. Thus, this article analyses the difference between the structural behavior of spatial arch bridges with Nielsen-type cable arrangements with respect to those with classical vertical hanger configurations. The main goal is to verify whether the known effectiveness of the Nielsen cable arrangement for classical arch bridges is still preserved when applied to spatial arch bridges. In order to achieve this objective, and as the first part of our study, a set of different all-steel bridges composed of vertical and inclined arches with straight decks have been compared for both cable arrangements. As a major conclusion, for planar vertical arch bridges, the Nielsen-type cable arrangement is always the most effective. In addition, it also seems that, for spatial arch bridges composed of a straight deck and an inclined arch, it still keeps most of its effectiveness as long as the arch is moderately inclined.

Risk of Cognitive Impairment in Patients With Parkinson’s Disease With Visual Hallucinations and Subjective Cognitive Complaints

Diego Santos-García,Teresa de Deus Fonticoba,Carlos Cores Bartolomé,Maria J. Feal Painceiras,Jose M. Paz González,Cristina Martínez Miró,Silvia Jesús,Miquel Aguilar,Pau Pastor,Lluís Planellas,Marina C 대한신경과학회 2023 Journal of Clinical Neurology Vol.19 No.4

Background and Purpose Visual hallucinations (VH) and subjective cognitive complaints (SCC) are associated with cognitive impairment (CI) in Parkinson’s disease. Our aims were to determine the association between VH and SCC and the risk of CI development in a cohort of patients with Parkinson’s disease and normal cognition (PD-NC). Methods Patients with PD-NC (total score of >80 on the Parkinson’s Disease Cognitive Rating Scale [PD-CRS]) recruited from the Spanish COPPADIS cohort from January 2016 to November 2017 were followed up after 2 years. Subjects with a score of ≥1 on domain 5 and item 13 of the Non-Motor Symptoms Scale at baseline (V0) were considered as “with SCC” and “with VH,” respectively. CI at the 2-year follow-up (plus or minus 1 month) (V2) was defined as a PD-CRS total score of <81. Results At V0 (n=376, 58.2% males, age 61.14±8.73 years [mean±SD]), the frequencies of VH and SCC were 13.6% and 62.2%, respectively. VH were more frequent in patients with SCC than in those without: 18.8% (44/234) vs 4.9% (7/142), p<0.0001. At V2, 15.2% (57/376) of the patients had developed CI. VH presenting at V0 was associated with a higher risk of CI at V2 (odds ratio [OR]=2.68, 95% confidence interval=1.05–6.83, p=0.039) after controlling for the effects of age, disease duration, education, medication, motor and nonmotor status, mood, and PD-CRS total score at V0. Although SCC were not associated with CI at V2, presenting both VH and SCC at V0 increased the probability of having CI at V2 (OR=3.71, 95% confidence interval= 1.36–10.17, p=0.011). Conclusions VH were associated with the development of SCC and CI at the 2-year follow-up in patients with PD-NC.

Thermoluminescence of NaCl:Cu Sintered Phosphors Exposed to Beta Irradiation

R. Bernal,C. Cruz-Vázquez,F. Brown,W. Tostado-García,R. Pérez-Salas,V.M. Castaño 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.4

NaCl:Cu pellet-shaped phosphors were synthesized through a sintering process. Some samples were exposed to beta irradiation in order to investigate their thermoluminescence properties and capabilities to be used in detecting and measuring ionizing radiation. The glow curves reveal at least four thermoluminescence peaks below 250°C, and a main one above 300°C when a 5°C/s heating rate is used. The lowest temperature peak vanishes in less than 3 min after irradiation, giving rise to an intense afterglow luminescence, potentially useful for in situ non-thermoluminescence dosimetry, and the next remains for about 3 h, but the high temperature one exhibits no important changes after that time. The thermoluminescence intensity increased as the radiation dose increased in the 0.417 - 25.0 Gy dose range. Because the position and the remarkable stability of the higher temperature peak, besides the strong afterglow produced by the fast decaying of the lower temperature peak, it is concluded that these phosphors are very suitable candidates to be used in both thermoluminescence and non thermoluminescence dosimetry of ionizing radiation, having advantages over monocrystals of similar composition. The synthesis route here followed can be reproduced in standard college laboratories, and thermoluminescence be measured in home-made systems, allowing design practices for interdisciplinary physics, chemistry electronics, and materials science students.