PEDRO RAMIREZ - Academia.edu (original) (raw)

Papers by PEDRO RAMIREZ

Research paper thumbnail of The influence of pre-fermentative maceration and ageing factors on ester profile and marker determination of Pedro Ximenez sparkling wines

Food Chemistry, 2017

The influence of pre-fermentative maceration and ageing factors on the ester profiles of Pedro Xi... more The influence of pre-fermentative maceration and ageing factors on the ester profiles of Pedro Ximenez sparkling wines was evaluated. The pre-fermentative maceration consisted of the skin-maceration of musts at 10 ºC for 6 hours. The sparkling wines were produced following the Champenoise method. Samples were monitored at 3, 6 and 9 months of ageing on lees. Sparkling wines with pre-fermentative maceration displayed higher contents of ethyl esters of branched acids and cinnamates. Meanwhile, those without maceration showed higher levels of ethyl esters of fatty acids and higher alcohol acetates. The study of statistical interactions elucidated different hydrolytic kinetics and developments in higher alcohol acetates and ethyl esters of branched acids during ageing. The application of a dual criterion based on univariate (ANOVA) and multivariate analyses (OPLS-DA) allowed us to identify new potential volatile markers related to pre-fermentative maceration and ageing time, reported for the first time in sparkling wines.

Research paper thumbnail of N = 2 <span class="katex-display"><span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML" display="block"><semantics><mrow><mi mathvariant="script">N</mi><mo>=</mo><mn>2</mn></mrow><annotation encoding="application/x-tex">\mathcal{N}=2</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.6833em;"></span><span class="mord mathcal" style="margin-right:0.14736em;">N</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:0.6444em;"></span><span class="mord">2</span></span></span></span></span> Einstein-Yang-Mills’ static two-center solutions

Journal of High Energy Physics, 2014

We construct bona fide one-and two-center supersymmetric solutions to N = 2, d = 4 supergravity c... more We construct bona fide one-and two-center supersymmetric solutions to N = 2, d = 4 supergravity coupled to SU(2) non-Abelian vector multiplets. The solutions describe black holes and global monopoles alone or in equilibrium with each other and exhibit non-Abelian hairs of different kinds.

Research paper thumbnail of Direct Conversion of Methane to Methanol on Ni-Ceria Surfaces: Metal-Support Interactions and Water-enabled Catalytic Conversion by Site Blocking

Journal of the American Chemical Society, Jun 28, 2018

The transformation of methane into methanol or higher alcohols at moderate temperature and pressu... more The transformation of methane into methanol or higher alcohols at moderate temperature and pressure conditions is of great environmental interest and remains a challenge despite many efforts. Extended surfaces of metallic nickel are inactive for a direct CH4  CH3OH conversion. This experimental and computational study provides clear evidence that low Ni loadings on a CeO2(111) support can perform a direct catalytic cycle for the generation of methanol at low temperature using oxygen and water as reactants, with a higher selectivity than ever reported for ceria-based catalysts. On the basis of ambient pressure X-ray photoemission spectroscopy and density functional theory calculations, we demonstrate that water plays a crucial role in blocking catalyst sites where methyl species could fully decompose, an essential factor for diminishing the production of CO and CO2, and in generating sites on which methoxy species and ultimately methanol can form. In addition to water-site blocking,...

Research paper thumbnail of Hydrogenation of CO2 on ZnO/Cu(100) and ZnO/Cu(111) Catalysts: Role of Copper Structure and Metal-Oxide Interface in Methanol Synthesis

The journal of physical chemistry. B, Jan 21, 2017

The results of kinetic tests and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) show ... more The results of kinetic tests and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) show the important role played by a ZnO-copper interface in the generation of CO and the synthesis of methanol from CO2 hydrogenation. The deposition of nanoparticles of ZnO on Cu(100) and Cu(111), θoxi < 0.3 monolayer, produces highly active catalysts. The catalytic activity of these systems increases in the sequence: Cu(111) < Cu(100) < ZnO/Cu(111) < ZnO/Cu(100). The structure of the copper substrate influences the catalytic performance of a ZnO-copper interface. Furthermore, size and metal-oxide interactions affect the chemical and catalytic properties of the oxide making the supported nanoparticles different from bulk ZnO. The formation of a ZnO-copper interface favors the binding and conversion of CO2 into a formate intermediate that is stable on the catalyst surface up to temperatures above 500 K. Alloys of Zn with Cu(111) and Cu(100) were not stable at the elevated temperat...

Research paper thumbnail of Highly Active Au/δ-MoC and Cu/δ-MoC Catalysts for the Conversion of CO2: The Metal/C Ratio as a Key Factor Defining Activity, Selectivity, and Stability

Journal of the American Chemical Society, Jul 16, 2016

The ever growing increase of CO2 concentration in the atmosphere is one of the main causes of glo... more The ever growing increase of CO2 concentration in the atmosphere is one of the main causes of global warming. Thus, CO2 activation and conversion towards valuable added compounds is a major scientific challenge. A new set of Au/δ-MoC and Cu/δ-MoC catalysts exhibits high activity, selectivity, and stability for the reduction of CO2 to CO with some subsequent selective hydrogenation towards methanol. Sophisticated experiments under controlled conditions and calculations based on density functional theory have been used to study the unique behavior of these systems. A detailed comparison of the behavior of Au/-Mo2C and Au/δ-MoC catalysts provides clear evidence of the impact of the metal/carbon ratio in the carbide on the performance of the catalysts. The present results show that this ratio governs the chemical behavior of the carbide and the properties of the admetal. Overall, as a result of metal-support interactions and a synergy at the metal-carbide interface, Au/δ-MoC and Cu/δ-M...

Research paper thumbnail of In situ Investigation of Methane Dry Reforming on M-CeO2(111) {M= Co, Ni, Cu} Surfaces: Metal-Support Interactions and the activation of C-H bonds at Low Temperature

Angewandte Chemie (International ed. in English), Jan 16, 2017

Studies with a series of M-CeO2(111) {M= Co, Ni, Cu} surfaces indicate that metal-oxide interacti... more Studies with a series of M-CeO2(111) {M= Co, Ni, Cu} surfaces indicate that metal-oxide interactions can play a very important role for the activation of methane and its reforming with CO2 at relatively low temperatures (600-700 K). Among the systems examined, Co-CeO2(111) exhibits the best performance and Cu-CeO2(111) has negligible activity. Experiments using ambient pressure XPS indicate that methane dissociates on Co-CeO2(111), at temperatures as low as 300 K, generating CHx and COx species on the catalyst surface. The results of density-functional calculations show a reduction in the methane activation barrier from 1.07 eV on Co(0001) to 0.87 eV on Co2+/CeO2(111), and to only 0.05 eV on Co0/CeO2-x(111). At 700 K, under methane dry reforming conditions, CO2 dissociates on the oxide surface and a catalytic cycle is established without coke deposition. A significant part of the CHx formed on the Co0/CeO2-x (111) catalyst recombines to yield ethane or ethylene.

Research paper thumbnail of Ciliates in a waste stabilization pond system in Mexico

Water, Air, and Soil Pollution, 1987

Abstract. A protozoological survey was performed on a waste-stabilization pond to isolate, identi... more Abstract. A protozoological survey was performed on a waste-stabilization pond to isolate, identify, and determine the incidence of ciliates present in these waters. The correlation between the species found and the physicochemical parameters was investigated. One hundred ...

Research paper thumbnail of A comparison between the spatial distribution pattern of flagellates and some physicochemical parameters in a waste stabilization pond

Water, Air, and Soil Pollution, 1988

Protozoological and physicochemical analyses were performed in a waste stabilization pond at Sto.... more Protozoological and physicochemical analyses were performed in a waste stabilization pond at Sto. Tomas Atzingo, a small town near Mexico City, in order to discern the internal dynamics of the pond water through the study of the spatial distribution pattern of flagellates and the parallel water volume distribution pattern of some selected physicochemical determined parameters. The statistical method applied to the data obtained was by cluster analysis. The results showed a slight trend to heterogeneity in the system, when it was evaluated through the physicochemically determined parameters. On the other hand, the spatial distribution pattern of the flagellates pointed out a remarkable heterogeneity in the pond. In systems like the one studied where the main feature is an organic matter overload, such a difference in findings indicates a low correlation between the biological parameters, in this case the flagellates, and the physicochemical variables, that should be considered when evaluating the water quality of such systems, either through the physicochemical, the biological or both scopes.

Research paper thumbnail of P2. 1 Two New Undergraduate Earth Science Web Modules in Air-Sea Interactions

Efforts to increase student learning and incorporate technology in the classroom have led to the ... more Efforts to increase student learning and incorporate technology in the classroom have led to the development of many interactive internet activities for earth science instruction. These activities make use of the burgeoning earth science resources available online and through other outlets. Digital libraries for earth system sciences have become clearinghouses for many online resources (Ginger and Marlino 2002). We have developed two interdisciplinary web-based modules that make use of online resources and that were intended to increase ...

Research paper thumbnail of Two new undergraduate earth science web modules in air-sea interactions

12th Symposium on Education, Feb 10, 2003

Two on-line learning activities were introduced to students in general education undergraduate co... more Two on-line learning activities were introduced to students in general education undergraduate courses in Earth Science and Oceanography using course WebCT homepages. Both modules incorporate satellite images, illustrations, and animations assembled mainly from NASA and NOAA Internet websites and educational CD-ROM's. These sources of information, mostly satellite imagery, are used to guide undergraduate students in learning important concepts of atmosphere-ocean interactions. The modules ...

Research paper thumbnail of Reduction of .ALPHA.,.BETA.-unsaturated carbonyl compounds to the saturated alcohols using hydridocarbonyliron complexes

Bulletin of the Chemical Society of Japan, 1982

Research paper thumbnail of The influence of pre-fermentative maceration and ageing factors on ester profile and marker determination of Pedro Ximenez sparkling wines

Food Chemistry, 2017

The influence of pre-fermentative maceration and ageing factors on the ester profiles of Pedro Xi... more The influence of pre-fermentative maceration and ageing factors on the ester profiles of Pedro Ximenez sparkling wines was evaluated. The pre-fermentative maceration consisted of the skin-maceration of musts at 10 ºC for 6 hours. The sparkling wines were produced following the Champenoise method. Samples were monitored at 3, 6 and 9 months of ageing on lees. Sparkling wines with pre-fermentative maceration displayed higher contents of ethyl esters of branched acids and cinnamates. Meanwhile, those without maceration showed higher levels of ethyl esters of fatty acids and higher alcohol acetates. The study of statistical interactions elucidated different hydrolytic kinetics and developments in higher alcohol acetates and ethyl esters of branched acids during ageing. The application of a dual criterion based on univariate (ANOVA) and multivariate analyses (OPLS-DA) allowed us to identify new potential volatile markers related to pre-fermentative maceration and ageing time, reported for the first time in sparkling wines.

Research paper thumbnail of N = 2 <span class="katex-display"><span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML" display="block"><semantics><mrow><mi mathvariant="script">N</mi><mo>=</mo><mn>2</mn></mrow><annotation encoding="application/x-tex">\mathcal{N}=2</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.6833em;"></span><span class="mord mathcal" style="margin-right:0.14736em;">N</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:0.6444em;"></span><span class="mord">2</span></span></span></span></span> Einstein-Yang-Mills’ static two-center solutions

Journal of High Energy Physics, 2014

We construct bona fide one-and two-center supersymmetric solutions to N = 2, d = 4 supergravity c... more We construct bona fide one-and two-center supersymmetric solutions to N = 2, d = 4 supergravity coupled to SU(2) non-Abelian vector multiplets. The solutions describe black holes and global monopoles alone or in equilibrium with each other and exhibit non-Abelian hairs of different kinds.

Research paper thumbnail of Direct Conversion of Methane to Methanol on Ni-Ceria Surfaces: Metal-Support Interactions and Water-enabled Catalytic Conversion by Site Blocking

Journal of the American Chemical Society, Jun 28, 2018

The transformation of methane into methanol or higher alcohols at moderate temperature and pressu... more The transformation of methane into methanol or higher alcohols at moderate temperature and pressure conditions is of great environmental interest and remains a challenge despite many efforts. Extended surfaces of metallic nickel are inactive for a direct CH4  CH3OH conversion. This experimental and computational study provides clear evidence that low Ni loadings on a CeO2(111) support can perform a direct catalytic cycle for the generation of methanol at low temperature using oxygen and water as reactants, with a higher selectivity than ever reported for ceria-based catalysts. On the basis of ambient pressure X-ray photoemission spectroscopy and density functional theory calculations, we demonstrate that water plays a crucial role in blocking catalyst sites where methyl species could fully decompose, an essential factor for diminishing the production of CO and CO2, and in generating sites on which methoxy species and ultimately methanol can form. In addition to water-site blocking,...

Research paper thumbnail of Hydrogenation of CO2 on ZnO/Cu(100) and ZnO/Cu(111) Catalysts: Role of Copper Structure and Metal-Oxide Interface in Methanol Synthesis

The journal of physical chemistry. B, Jan 21, 2017

The results of kinetic tests and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) show ... more The results of kinetic tests and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) show the important role played by a ZnO-copper interface in the generation of CO and the synthesis of methanol from CO2 hydrogenation. The deposition of nanoparticles of ZnO on Cu(100) and Cu(111), θoxi < 0.3 monolayer, produces highly active catalysts. The catalytic activity of these systems increases in the sequence: Cu(111) < Cu(100) < ZnO/Cu(111) < ZnO/Cu(100). The structure of the copper substrate influences the catalytic performance of a ZnO-copper interface. Furthermore, size and metal-oxide interactions affect the chemical and catalytic properties of the oxide making the supported nanoparticles different from bulk ZnO. The formation of a ZnO-copper interface favors the binding and conversion of CO2 into a formate intermediate that is stable on the catalyst surface up to temperatures above 500 K. Alloys of Zn with Cu(111) and Cu(100) were not stable at the elevated temperat...

Research paper thumbnail of Highly Active Au/δ-MoC and Cu/δ-MoC Catalysts for the Conversion of CO2: The Metal/C Ratio as a Key Factor Defining Activity, Selectivity, and Stability

Journal of the American Chemical Society, Jul 16, 2016

The ever growing increase of CO2 concentration in the atmosphere is one of the main causes of glo... more The ever growing increase of CO2 concentration in the atmosphere is one of the main causes of global warming. Thus, CO2 activation and conversion towards valuable added compounds is a major scientific challenge. A new set of Au/δ-MoC and Cu/δ-MoC catalysts exhibits high activity, selectivity, and stability for the reduction of CO2 to CO with some subsequent selective hydrogenation towards methanol. Sophisticated experiments under controlled conditions and calculations based on density functional theory have been used to study the unique behavior of these systems. A detailed comparison of the behavior of Au/-Mo2C and Au/δ-MoC catalysts provides clear evidence of the impact of the metal/carbon ratio in the carbide on the performance of the catalysts. The present results show that this ratio governs the chemical behavior of the carbide and the properties of the admetal. Overall, as a result of metal-support interactions and a synergy at the metal-carbide interface, Au/δ-MoC and Cu/δ-M...

Research paper thumbnail of In situ Investigation of Methane Dry Reforming on M-CeO2(111) {M= Co, Ni, Cu} Surfaces: Metal-Support Interactions and the activation of C-H bonds at Low Temperature

Angewandte Chemie (International ed. in English), Jan 16, 2017

Studies with a series of M-CeO2(111) {M= Co, Ni, Cu} surfaces indicate that metal-oxide interacti... more Studies with a series of M-CeO2(111) {M= Co, Ni, Cu} surfaces indicate that metal-oxide interactions can play a very important role for the activation of methane and its reforming with CO2 at relatively low temperatures (600-700 K). Among the systems examined, Co-CeO2(111) exhibits the best performance and Cu-CeO2(111) has negligible activity. Experiments using ambient pressure XPS indicate that methane dissociates on Co-CeO2(111), at temperatures as low as 300 K, generating CHx and COx species on the catalyst surface. The results of density-functional calculations show a reduction in the methane activation barrier from 1.07 eV on Co(0001) to 0.87 eV on Co2+/CeO2(111), and to only 0.05 eV on Co0/CeO2-x(111). At 700 K, under methane dry reforming conditions, CO2 dissociates on the oxide surface and a catalytic cycle is established without coke deposition. A significant part of the CHx formed on the Co0/CeO2-x (111) catalyst recombines to yield ethane or ethylene.

Research paper thumbnail of Ciliates in a waste stabilization pond system in Mexico

Water, Air, and Soil Pollution, 1987

Abstract. A protozoological survey was performed on a waste-stabilization pond to isolate, identi... more Abstract. A protozoological survey was performed on a waste-stabilization pond to isolate, identify, and determine the incidence of ciliates present in these waters. The correlation between the species found and the physicochemical parameters was investigated. One hundred ...

Research paper thumbnail of A comparison between the spatial distribution pattern of flagellates and some physicochemical parameters in a waste stabilization pond

Water, Air, and Soil Pollution, 1988

Protozoological and physicochemical analyses were performed in a waste stabilization pond at Sto.... more Protozoological and physicochemical analyses were performed in a waste stabilization pond at Sto. Tomas Atzingo, a small town near Mexico City, in order to discern the internal dynamics of the pond water through the study of the spatial distribution pattern of flagellates and the parallel water volume distribution pattern of some selected physicochemical determined parameters. The statistical method applied to the data obtained was by cluster analysis. The results showed a slight trend to heterogeneity in the system, when it was evaluated through the physicochemically determined parameters. On the other hand, the spatial distribution pattern of the flagellates pointed out a remarkable heterogeneity in the pond. In systems like the one studied where the main feature is an organic matter overload, such a difference in findings indicates a low correlation between the biological parameters, in this case the flagellates, and the physicochemical variables, that should be considered when evaluating the water quality of such systems, either through the physicochemical, the biological or both scopes.

Research paper thumbnail of P2. 1 Two New Undergraduate Earth Science Web Modules in Air-Sea Interactions

Efforts to increase student learning and incorporate technology in the classroom have led to the ... more Efforts to increase student learning and incorporate technology in the classroom have led to the development of many interactive internet activities for earth science instruction. These activities make use of the burgeoning earth science resources available online and through other outlets. Digital libraries for earth system sciences have become clearinghouses for many online resources (Ginger and Marlino 2002). We have developed two interdisciplinary web-based modules that make use of online resources and that were intended to increase ...

Research paper thumbnail of Two new undergraduate earth science web modules in air-sea interactions

12th Symposium on Education, Feb 10, 2003

Two on-line learning activities were introduced to students in general education undergraduate co... more Two on-line learning activities were introduced to students in general education undergraduate courses in Earth Science and Oceanography using course WebCT homepages. Both modules incorporate satellite images, illustrations, and animations assembled mainly from NASA and NOAA Internet websites and educational CD-ROM's. These sources of information, mostly satellite imagery, are used to guide undergraduate students in learning important concepts of atmosphere-ocean interactions. The modules ...

Research paper thumbnail of Reduction of .ALPHA.,.BETA.-unsaturated carbonyl compounds to the saturated alcohols using hydridocarbonyliron complexes

Bulletin of the Chemical Society of Japan, 1982