15 results on '"Miriam Benitez"'
Search Results
2. Harmonious Passion at Work: Personal Resource for Coping with the Negative Relationship between Burnout and Intrinsic Job Satisfaction in Service Employees
- Author
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Miriam Benitez, Alejandro Orgambídez, Francisco J. Cantero-Sánchez, and Jose M. León-Pérez
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Health, Toxicology and Mutagenesis ,Public Health, Environmental and Occupational Health ,work harmonious passion ,burnout ,intrinsic job satisfaction ,service organizations - Abstract
Research about harmonious passion as a personal resource that can have a protective effect in situations of stress and burnout is scarce but growing. Considering the job demands-resources (JD-R) model, the present study aims to address the above gaps by exploring the moderating role of harmonious passion at work in the relationship between burnout (physical fatigue, cognitive weariness, and emotional exhaustion) and intrinsic job satisfaction. The study sample consisted of 748 workers from service organizations (front-line employees) in southern Spain (Mage = 35.51, SD = 10.06, 52% women). Using statistical program R (R Core Team, 2022), the results of the regression models showed the moderating role of harmonious passion on the negative relationships between physical fatigue and intrinsic job satisfaction. In particular, at high levels of physical fatigue, employees with high scores on harmonious passion at work presented higher levels of intrinsic satisfaction compared with employees with low passion at work. That is, although service employees have high levels of physical fatigue, when they are passionate, they still possess satisfaction with their work. Therefore, our findings extend the JD-R theory by considering harmonious passion as a motivational resource that reduce feelings of burnout in service employees. Hence, it shows the importance of promoting the autonomous internalization of work, (through, i.e., job enrichment), which allows the development of harmonious passion at work and, therefore, increasing intrinsic job satisfaction.
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- 2023
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3. A travel though the atrane route, a versatile tool for the materials soft‐synthesis: A twenty‐five years perspective
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María Dolores Garrido, Miriam Benítez, Jose V. Ros‐Lis, and Pedro Amorós
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atrane ,oxides ,silica ,sol‐gel ,triethanolamine ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Abstract The use of triethanolamine in the preparation of materials has been a fertile area of research during the last decades. It is used in sol‐gel synthesis because of its ability to regulate pH, act as a structure‐directing agent, and form atrane complexes with a wide variety of elements. The atranes harmonize the hydrolysis and condensation processes of inorganic species with their interaction with surfactant molecules or micelles for the obtention of homogeneous materials. This review describes the basic principles of the formation of atrane complexes and their use in material synthesis, followed by a compilation of the main examples found in the bibliography. These materials include pure and doped silicas by using micelles as porogen species (MCM‐41, SBA‐15, UVM‐7, etc.), or without using template agents (TUD‐1, UVM‐11, etc.), non‐silica oxides (Al2O3, TiO2, ZrO2, etc.), mesoporous phosphates and phosphonates, zeotypes (zeolites, aluminophosphates or silicoaluminophosphates, and layered double hydroxides. The atrane route shows a versatile approach for the preparation of these materials with up to three elements simultaneously. The focus of the review centers on the synthesis of the materials and the discussion of their main applications. These examples enrich with a discussion about the future perspective of the topic.
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- 2024
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4. Advanced and traditional processing of thermoplastic polyurethane waste
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Tamara Calvo-Correas, Miriam Benitez, Izaskun Larraza, Lorena Ugarte, Cristina Peña-Rodríguez, and Arantxa Eceiza
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Polymers and Plastics ,Mechanics of Materials ,Materials Chemistry ,Condensed Matter Physics - Published
- 2022
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5. Electrochemiluminescence of a Periodic Mesoporous Organosilica Containing 9,10-Diarylanthracene Units
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Miriam Benitez, Mercedes Alvaro, and Hermenegildo García, Antonio Leyva, and Jose F. Cabeza
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Materials science ,Silicon ,Inorganic chemistry ,chemistry.chemical_element ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Tetraethyl orthosilicate ,Amorphous solid ,chemistry.chemical_compound ,Mesoporous organosilica ,General Energy ,chemistry ,Chemical engineering ,Electrochemiluminescence ,Physical and Theoretical Chemistry ,Mesoporous material ,Porosity ,Derivative (chemistry) - Abstract
A 9,10-diarylanthracene derivative having two terminal trimethoxysilyl groups has been synthesized and used in combination with tetraethyl orthosilicate as a silicon source for the preparation of two periodic mesoporous silicas with MCM-41 and SBA-15 structures having about 15 wt % of the organic component. The resulting solids exhibit electrochemiluminescence arising from the organic moieties. The benefit for the electrochemiluminescence activity of having a large surface area solid with periodic porous structure is revealed by the fact that an analogous amorphous material prepared with the same precursor does not exhibit any measurable electrochemiluminescence activity under the same conditions.
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- 2007
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6. Periodic mesoporous silica having covalently attached tris(bipyridine)ruthenium complex: synthesis, photovoltaic and electrochemiluminescent properties
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Josep Font, Miriam Benitez, Hermenegildo García, Eva Casas, Laura Teruel, Félix Busqué, and Pedro de March
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Tris ,Inorganic chemistry ,chemistry.chemical_element ,General Chemistry ,Mesoporous silica ,Ruthenium ,Bipyridine ,chemistry.chemical_compound ,Adsorption ,chemistry ,Transition metal ,Polymer chemistry ,Materials Chemistry ,Electrochemiluminescence ,Mesoporous material - Abstract
A tris(bipyridine)ruthenium derivative with two terminal triethoxysilyl groups attached to one of the bipyridine ligands has been synthesized and used in combination with TEOS for the preparation of a tris(bipyridine)ruthenium-containing mesoporous silica, using CTABr as a structure-directing agent, under basic conditions at 100 °C. The resulting solids exhibited XRD patterns, isothermal gas adsorption and electron-microscopy images characteristic of hexagonal mesoporous silica, while the presence of tris(bipyridine)ruthenium complexes at the walls is manifested by the orange coloration of the solids and the optical spectra of the material corresponding to tris(bipyridine)ruthenium(II). The removal of the structure-directing agent without damaging the complex or the mesoporous structure of the pores was done by exhaustive solid–liquid extraction. As-synthesized mpRu exhibits photovoltaic (VOC = 140 mV, ISC = 2.6 µA) and electrochemiluminescence activity (λmax = 610 nm), the presence of CTABr plays a positive role in the activity by promoting intraparticle charge migration. In contrast, for an analogous material prepared under the same conditions but in the absence of the structure-directing agent and having a low surface area, the amorphous structure did not exhibit significant a photovoltaic or electrochemiluminescence response. This result exemplifies the benefits of having porosity and accessibility to the photoactive metallic complexes.
- Published
- 2007
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7. Urea-Containing Mesoporous Silica for the Adsorption of Fe(III) Cations
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Hermenegildo García, Miriam Benitez, Uwe Pischel,† and, Rita Ferreira, and Debasish Das
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Thermogravimetric analysis ,Materials science ,Silicon ,General Chemical Engineering ,Inorganic chemistry ,chemistry.chemical_element ,General Chemistry ,Mesoporous silica ,chemistry.chemical_compound ,Adsorption ,X-ray photoelectron spectroscopy ,chemistry ,Oxidation state ,Materials Chemistry ,Urea ,Spectroscopy - Abstract
A urea-containing mesoporous silica with intraframework urea groups (UreaMS) was synthesized via a surfactant-templated route by co-condensation of an organosilane precursor and tetraethoxysilane. The material possesses hexagonal pores with a high degree of uniformity and shows long-range order as confirmed by the measurement of powder X-ray diffraction and N2 adsorption isotherms. A detailed characterization by chemical analysis, 29Si MAS NMR, X-ray photoelectron spectroscopy, thermogravimetric analysis, and FT-IR spectroscopy confirmed the integrity of urea groups inside the walls of the material. The results revealed a density of one urea group per ca. 13−16 silicon atoms. The efficiency of UreaMS for the adsorption of Fe(III) cations was tested. A distribution coefficient of Kd = 700 mL g-1 and an adsorption capacity of 0.19 mmol g-1 were determined. X-ray photoelectron spectroscopy confirmed the conservation of the oxidation state +3 for the iron within the mesoporous silica material.
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- 2006
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8. Second harmonic generation of a periodic mesoporous silica containing a triphenylpyrylium moiety
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Mercedes Alvaro, Hermenegildo García, Miriam Benitez, José Raúl Herance, José Luis Bourdelande, and Carmela Aprile
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Chemistry ,Inorganic chemistry ,General Physics and Astronomy ,Second-harmonic generation ,Mesoporous silica ,Photochemistry ,Ion ,chemistry.chemical_compound ,Bromide ,Moiety ,Physical and Theoretical Chemistry ,Mesoporous material ,Excitation ,BET theory - Abstract
A periodic mesoporous SBA-15 silica containing 4,4-(N,N′- diallylaminophenyl)-2,6-diphenylpyrylium ion (BET surface area of 578 m 2 g-1, pore size 5.2 nm) exhibits upon excitation at 1064 nm activity for second harmonic generation that is the double than that of an analogous MCM-41 material synthesized under basic conditions using cetyltrimethylammonium bromide. This fact has been explained as arising from the instability of pyrylium to basic pHs.
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- 2005
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9. Reversible Porosity Changes in Photoresponsive Azobenzene-Containing Periodic Mesoporous Silicas
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Debashis Das, Miriam Benitez, Hermenegildo García, Encarna Peris, and Mercedes Alvaro
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Materials science ,General Chemical Engineering ,General Chemistry ,Mesoporous silica ,Photochemistry ,Tetraethyl orthosilicate ,chemistry.chemical_compound ,Mesoporous organosilica ,Adsorption ,chemistry ,Azobenzene ,Materials Chemistry ,Mesoporous material ,Isomerization ,Cis–trans isomerism - Abstract
Two differently substituted azobenzenes having terminal trimethoxysilyl groups attached to the para position of the phenyl rings by means of different linkers have been used in combination with tetraethyl orthosilicate to prepare two periodic mesoporous organosilicas. As the corresponding precursors in solution, these solids exhibit a photochemical trans-to-cis isomerization of the azo group upon irradiation at 358 nm. The cis-configured isomer reverts to the trans isomer either photochemically upon irradiation at 450 nm or thermally at room temperature within days. As a consequence of the dramatic changes in the molecular dimension of azobenzene upon trans/cis isomerization, the adsorption of gold nanoparticles (1−10 nm) into the mesoporous silica depends reversibly on the trans or cis configuration of the azo groups grafted on the walls, the adsorption capacity of the trans-configured azobenzene being larger.
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- 2005
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10. Synthesis of Chiral Periodic Mesoporous Silicas (ChiMO) of MCM-41 Type with Binaphthyl and Cyclohexadiyl Groups Incorporated in the Framework and Direct Measurement of Their Optical Activity
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Hermenegildo García, Debasish Das, Mercedes Alvaro, Miriam Benitez, and Belén Ferrer
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chemistry.chemical_classification ,Materials science ,General Chemical Engineering ,Inorganic chemistry ,General Chemistry ,Polymer ,Powder xrd ,Fluorescence ,Silicate ,Crystallography ,chemistry.chemical_compound ,chemistry ,MCM-41 ,Covalent bond ,Materials Chemistry ,Mesoporous material ,Porosity - Abstract
A series of periodic mesoporous silicas of MCM-41 type containing varying amounts (5−50%) of chiral binaphthyl and cyclohexadiyl moieties occupying framework positions have been synthesized, and their characteristic MCM-41 features were observed by powder XRD and porosity measurements. The covalent bonding of the organics to the silicate framework was confirmed by 1H and 29Si MAS NMR experiments. Direct measurement of the optical activity demonstrates that the solids are able to rotate the angle of plane-polarized light. Also, a certain degree of chiral discrimination has been observed for the asymmetric enhancement of the binaphthyl fluorescence by adding enantiomerically pure 1,2-cyclohexadiamine.
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- 2004
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11. Photocatalytic activity of structured mesoporous TiO2 materials
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Mercedes Alvaro, Carmela Aprile, Hermenegildo García, Miriam Benitez, and Esther Carbonell
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Aqueous solution ,Materials science ,Inorganic chemistry ,chemistry.chemical_element ,Surfaces, Coatings and Films ,Tetraethyl orthosilicate ,chemistry.chemical_compound ,Mesoporous organosilica ,Adsorption ,chemistry ,Chemical engineering ,Materials Chemistry ,Photocatalysis ,Physical and Theoretical Chemistry ,Mesoporous material ,Titanium ,BET theory - Abstract
Starting from colloidal TiO2 nanoparticles in combination with tetraethyl orthosilicate using neutral Pluronic or cationic cetyltrimethylammonium as templates, a series of structured mesoporous silicas has been obtained. The structure of the mesoporous titania was confirmed by isothermal gas adsorption, transmission electron microscopy, and X-ray diffraction. The pore diameter ranged between 3.8 and 10.9 nm, and the BET surface area varied from 99 to 584 m2 g-1. The photocatalytic activity of these samples for the degradation of phenol in aqueous solution has been compared with that of standard P-25 TiO2. Even though the activity of these new mesostructured materials is lower that those found for P-25 TiO2, the turnover frequency of the photocatalytic activity (moles of phenol degraded per Ti atom present at initial reaction time) is much higher for the mesoporous titania, particularly with low titanium contents for those materials (mpTiO2-5 and TiO 2-SBA15-5).
- Published
- 2006
12. Novel Microwave-Assisted Synthesis of COFs: 2020–2022
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Cristina Rodríguez-Carríllo, Miriam Benítez, Jamal El Haskouri, Pedro Amorós, and Jose V. Ros-Lis
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covalent organic framework ,microwave-assisted synthesis ,COF ,2D ,3D ,Organic chemistry ,QD241-441 - Abstract
Covalent organic frameworks (COFs) have emerged as a new type of crystalline porous polymers of great interest. However, their preparation requires long reaction times. Microwave-assisted synthesis (MAS) offers an interesting approach to increasing the reaction rate of chemical processes. Thus, microwaves can be a key tool for the fast and scalable synthesis of COFs. Since our previous review on the topic, the preparation of COFs with microwaves has been evolving. Herein, we present a compilation of COFs studies and experiments published in the last three years on the synthesis of COFs using microwave-assisted synthesis as a source of energy. The articles include imine, triazine, and other 2D COFs synthesized using MAS. The 3D COFs have also been compiled. The chemical structure of the monomers and the COFs and their main parameters of synthesis and application are summarized for each article.
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- 2023
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13. Batch and Flow Synthesis of CeO2 Nanomaterials Using Solid-State Microwave Generators
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Cristina Rodríguez-Carrillo, Juan Torres García, Miriam Benítez, Jamal El Haskouri, Pedro Amorós, and Jose V. Ros-Lis
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CeO2 ,nanoparticle ,microwave-assisted synthesis ,solid-state generator ,flow chemistry ,Organic chemistry ,QD241-441 - Abstract
Microwave-assisted synthesis in combination with flow synthesis offers an interesting approach to develop faster and more sustainable procedures for the preparation of homogeneous nanomaterials. Recently, solid-state generators of microwaves appeared as a tool with improved control over power and frequency. Cerium oxide, despite its excellent catalytic activity, has not been prepared before using solid-state generators or microwave-assisted flow chemistry. We report a procedure for the preparation of nanoparticulated CeO2 (around 4 nm) under 2.45 GHz microwaves in only 30 s. The materials are further calcined at 800 °C to increase particle size, with a better defined particle size and crystallinity. The procedure was tested in batch at pH 11 and 12 and diverse potencies, and the products were characterized by TEM, XRD, DLS, and N2 adsorption–desorption isotherms. The materials were similar at the diverse pH values and potencies. XRD confirms the crystallinity of the CeO2 material with a fluorite-like structure. They are composed of particles around 40 nm that aggregate as structures of around 100 nm. The procedure was successfully adapted to flow synthesis, obtaining materials with structure and properties equivalent to batch synthesis. The batch and flow materials offer peroxidase properties, opening the door for their use as ROS scavengers.
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- 2022
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14. Design of a Chiral Mesoporous Silica and Its Application as a Host for Stereoselective Di-π-methane Rearrangements
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Heiko Ihmels, Gerhard Bringmann, Michael Dreyer, Hermenegildo García, Kathrin Wissel, and Michael Waidelich, and Miriam Benitez
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Models, Molecular ,Chiral auxiliary ,Molecular Structure ,Organic Chemistry ,Stereoisomerism ,Mesoporous silica ,Silicon Dioxide ,chemistry.chemical_compound ,Mesoporous organosilica ,Adsorption ,Models, Chemical ,chemistry ,Polymer chemistry ,Organic chemistry ,Organosilicon Compounds ,Stereoselectivity ,Enantiomeric excess ,Mesoporous material ,Methane ,Porosity ,Linker - Abstract
[reaction: see text] A chiral periodic mesoporous organosilica (ChiMO) was prepared, in which a 1,2-bis-(ureido)cyclohexyl linker (38 wt %) is introduced into the walls of the hybrid organic-inorganic material. This silica was used as a host for 11-formyl-12-methyldibenzobarrelene (2), and the stereoselectivity of the di-pi-methane rearrangement of 2 within this host-guest complex was studied. At low conversions, the only product was the corresponding dibenzosemibullvalene. An enantiomeric excess of 24% at 11% conversion was obtained using the ChiMO as host. These values compare well with those achieved using a system based on conventional faujasites (LiY and NaY) as hosts incorporating a chiral auxiliary. We tested S-phenylglycine, S-proline, S-camphanic acid, and S-mandelic acid as chiral auxiliaries. In contrast to the behavior of the ChiMO material, adsorption of dibenzobarrelene in purely siliceous mesoporous MCM-41 silica (3.2 nm pore size) containing ephedrine failed, a failure that can be explained as arising from the large internal silanol population and high hydrophilicity of the siliceous MCM-41 sample.
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- 2005
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15. Coping with Interpersonal Conflict at Work in Small Business: The Moderating Role of Supervisor and Co-Worker Support
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Inés Martínez-Corts, Marina Boz, Francisco J. Medina, Miriam Benítez, and Lourdes Munduate
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Psychology ,BF1-990 - Abstract
La finalidad de este estudio fue analizar las relaciones existentes entre los tipos de conflicto y la satisfacción el trabajo en PYMES, analizando el papel moderador que diferentes fuentes de apoyo (compañeros y superior) pueden jugar en esta relación. Adoptando una perspectiva contingente en la gestión del conflicto organizacional, los principales hallazgos muestran que el apoyo del superior amortigua la relación entre el conflicto relacional y la satisfacción en el trabajo, mientras que el apoyo de los compañeros amortigua la relación entre el conflicto de tareas y la satisfacción en el trabajo. Además, el modelo que analiza la influencia del apoyo del supervisor y del conflicto relacional es más importante para predecir la satisfacción que el modelo que analiza la influencia del conflicto de tareas y del apoyo de los compañeros. Este estudio realiza una contribución al estudio del conflicto en organizaciones pequeñas, dos campos de trabajo que han sido estudiados de forma separada; del mismo modo, los hallazgos permiten la realización de implicaciones prácticas para el campo de la Gestión de los Recursos Humanos.
- Published
- 2011
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