In two contrasting agricultural ecohabitats (agrohabitats) in the avocado production area in the municipality of Cuernavaca, Morelos, an analysis of nutrimental status, soil fertility and water quality was conducted t...In two contrasting agricultural ecohabitats (agrohabitats) in the avocado production area in the municipality of Cuernavaca, Morelos, an analysis of nutrimental status, soil fertility and water quality was conducted to measure soil fertility levels and to determine the nutrimental state of the trees. The “Hass” variety avocado groves studied had an average age of 8 years;the first grove was planted in an acrisol soil (1700 to 1900 meters above mean sea level [mamsl]);the second, in an andosol soil (1200 to 1700 mamsl). In each agrohabitat, tests were performed to determine the soil’s physical and chemical characteristics. The physical and chemical characteristics of the soils of this zone differ as do the nutrimental states of the avocado trees in the two agrohabitats. The trees showed excessive concentration of Ca, Fe, S, Z and Mg. The indices of Deviation from Optimal Percentage (DOP) in the two agrohabitats showed different nutrimental requirements;nevertheless, they were low and very near to zero, 14.218 and 13.350 respectively. The water used for the agricultural irrigation was low in salinity and sodium content and thus may be used for the agricultural irrigation without restrictions.展开更多
The objective of the present work is modeling the mobility habitus in the public transport system with low Co2 emission mechanics in the center of Mexico.In this sense,a documentary work was carried out with a review ...The objective of the present work is modeling the mobility habitus in the public transport system with low Co2 emission mechanics in the center of Mexico.In this sense,a documentary work was carried out with a review of sources indexed to national repositories,using the Delphi technique for the content analysis and the specification of the model.A study was conducted with a selection of 100 students to establish the reliability,linearity,sphericity,adequacy,and validity of an instrument from which a relationship of dependence between income and mobility habitus was observed.The limits of the search,selection,and processing of information are recognized,and it is recommended to extend the research to international repositories,as well as to employ a more sophisticated technique.展开更多
It is very important for the car users to have several communication systems and many antennas, which respond to the demands of aesthetics and efficiency. In this case, it is necessary to consider different types of m...It is very important for the car users to have several communication systems and many antennas, which respond to the demands of aesthetics and efficiency. In this case, it is necessary to consider different types of materials and geometries. Among the automobile systems, the navigation systems are found, which are formed by a Global Position System (GPS), with a pre-charged base of maps and highways in order to locate the vehicle. For the reception of the GPS signals, circularly polarized patch antennas are used, which must be designed to operate at 1.57 GHz. This work is focused on the analysis of a circular antenna performance, designed for GPS, by means of the simulation of the following cases: antenna without radome, antenna with acrylic radome, and, finally, antenna on the roof of an automobile, considering the effect of the complete chassis. A Basic, a Simplified and a More Simplified Advanced Car Models (BCM, SACM, and MSACM) were used in order to analyze the chassis shape. The simulations were carried out with the software FEKO. The fabrication and experimental and practical tests are also presented.展开更多
Results of a soil radon survey accomplished by 2 different methods during 2 different periods in the area of Tlamacas Mountain are presented. The first study, carried out from 15-APR-2010 to 09-MAY-2010 in 30 measurem...Results of a soil radon survey accomplished by 2 different methods during 2 different periods in the area of Tlamacas Mountain are presented. The first study, carried out from 15-APR-2010 to 09-MAY-2010 in 30 measurement sites by means of CR39 solid state nuclear detectors, shows 2 active zones with intensive radon emanation with a characteristic dimension of about 300 meters located in the northwestern and western parts of the Mountain. The second survey, made on 05-JUL-2011 in 23 measurement sites with 10 min sampling by a SARAD RTM 1688 Radon/Thoron monitor, in contrast, revealed a sizeable area depleted in radon and 3 active areas of increased radon release in the lateral Mountain sides. These observed phenomena strengthen our assumption about the presence of an active geological structure in Tlamacas Mountain connected with a geodynamical processes in volcano Popocatepetl.展开更多
Ultrasound-assisted pretreatment under mild operating conditions has been investigated for intensification of delignification to facilitate the obtaining of ethyl levulinate from biomass. The effect of pH (2 - 12), te...Ultrasound-assisted pretreatment under mild operating conditions has been investigated for intensification of delignification to facilitate the obtaining of ethyl levulinate from biomass. The effect of pH (2 - 12), temperature (30°C - 70°C) and pretreatment time (0 - 120 minutes) has been studied for different biomass samples. The most favorable conditions were basic pH, temperature of 70°C and pretreatment time of 2 h, obtaining values of delignification near 80 percent. The ethyl levulinate is obtained in microwave directly via from samples before and after delignification and analyzed for GC-MS. The results evidenced better yields for the delignified samples.展开更多
High blood pressure is the main risk factor for cardiovascular diseases, it affects many people worldwide and is a public health problem. This study explored the acute and chronic actions of a mixture of turmeric (95%...High blood pressure is the main risk factor for cardiovascular diseases, it affects many people worldwide and is a public health problem. This study explored the acute and chronic actions of a mixture of turmeric (95% curcumin) plus black pepper (95% piperine) extracts, in the blood pressure pattern in spontaneously hypertensive rats (SHR) along they age. For the acute study male adult (4 - 7 months old) SHR and their control Wistar Kyoto rats (WKY) were used. A single oral dose of the mixture of turmeric/black pepper extracts (200 mg/2mg, respectively) suspension was administered. Tail-cuff was used to determine blood pressure during 180 min. For the chronic study, young (1-month-old) male SHR and their control WKY rats were fed with standard chow, or standard chow combined with cocoa, or combined with cocoa plus the mixture of turmeric/black pepper extracts;tail-cuff was used to determine blood pressure once a week, along 12 weeks. In a second chronic assay adult (5 months old) male SHR and their control WKY rats were fed with standard chow, or standard chow combined with cocoa, or combined with cocoa plus the mixture of turmeric/black pepper extracts;tail-cuff was used to determine blood pressure once a week, along 12 weeks. In all three studies, a decrease in systolic, diastolic and mean blood pressure was observed, being higher in SHR and negligible in WKY rats. The mixture of turmeric/black pepper extracts showed antihypertensive actions in SHR rats with no effect on WKY rats. The mixture delayed the onset of hypertension in young SHR rats.展开更多
A novel method of renormalization called Pacman renormalization allows us to study (unicritical) Siegel functions through Pacman-type functions. It has been used to investigate the Siegel parameters with combinatorial...A novel method of renormalization called Pacman renormalization allows us to study (unicritical) Siegel functions through Pacman-type functions. It has been used to investigate the Siegel parameters with combinatorially periodic rotation number in the main cardioid of the Mandelbrot set. It is already known that it can be defined a Pacman renormalization operator such that for Siegel pacmen, with combinatorially periodic rotation numbers, the operator is compact, analytic and has a unique fixed point, at which it is hyperbolic with one-dimensional unstable manifold. In this paper we observe that this Pacman renormalization operator is compact and analytic at any Siegel Pacman or Siegel map with combinatorially bounded rotation number. This allows us to define a renormalization operator on the hybrid classes of the standard Siegel pacmen to which we built its horseshoe where the operator is topologically semiconjugated to the left shift on the space of bi-infinite sequences of natural numbers bounded by some constant.展开更多
There are different types of pollutants that are harmful to the environment, including smog, chemicals that are dumped into rivers, scrap tires, etc. The latter have the particularity that it is not possible to recycl...There are different types of pollutants that are harmful to the environment, including smog, chemicals that are dumped into rivers, scrap tires, etc. The latter have the particularity that it is not possible to recycle them to manufacture new tires. In the present work, hydraulic concrete plates added with waste tire rubber were manufactured to modify their sound absorption capacity. It was found that the rubber additions produce changes in the density of the material and in the sound absorption capacity. When the material is exposed to high-frequency sounds that correspond to high-pitched sounds, its absorption capacity increases. On the contrary, when the test frequency is low, that is, bass sounds, the sound absorption capacity decreases. The results obtained in this work suggest that the proposed mixtures are suitable for the possible manufacture of acoustic insulating shields.展开更多
An ultrasound-assisted heterogeneous catalytic oxidation process was applied to eliminate sulfur from commercial diesel fuel oil.The studied variables were catalyst concentration,type of catalyst(homogeneous or hetero...An ultrasound-assisted heterogeneous catalytic oxidation process was applied to eliminate sulfur from commercial diesel fuel oil.The studied variables were catalyst concentration,type of catalyst(homogeneous or heterogeneous),oxidizing agent concentration,and the application of ultrasound energy.Supported catalysts were prepared by impregnation of coal fly ash with an iron(Ⅱ)sulfate aqueous solution using ultrasound energy.After drying,the catalyst was calcined at 500℃for 4 h.The oxidizing agent was hydrogen peroxide.Ultrasound energy was applied with a frequency of 47 kHz and an intensity of 147 W.Ethanol was employed for extracting the oxidized compounds from the hydrocarbon mixture.Coal fly ash and ethanol were used with the purpose of applying low-cost raw materials in chemical processes.It was found that under the studied conditions,increasing oxidizing agent concentration and the application of ultrasound energy can enhance the sulfur removal from commercial diesel fuel oil.Catalyst concentration did not play a significant role in the process.Similar results were obtained using homogeneous or heterogeneous catalyst,which is important since the heterogeneous catalyst could be recovered,reactivated,and used in many cycles.展开更多
In this work, the estimation of crack initiation life of a hydraulic Francis turbine runner is presented. The life prediction is based on the local strain approach to predict the initiation life. First, the analysis i...In this work, the estimation of crack initiation life of a hydraulic Francis turbine runner is presented. The life prediction is based on the local strain approach to predict the initiation life. First, the analysis is carried out in air and in water condition and the runner’s natural frequencies were calculated using the finite element (FE) method. The analysis in air is compared with experimental analysis in order to have a representative model of real runner and subsequently the numerical analysis was perform in water. In the case of the runner immersed in water, the added mass effect due to the fluid structure interaction (FSI) is considered. Second, the static and dynamic stresses were calculated according to life estimation. For the calculation of static stresses, the pressure distribution of water and the centrifugal forces were applied to the runner. The dynamic stresses were estimated for interactions between the guide vane and the runner. Lastly, the estimation of the crack initiation life of the runner was obtained.展开更多
In this work, an analysis of the generation, composition and management of the urban solid waste in Mexico and its relation to greenhouse gas emissions is described;as well a case study in Morelos, a state in the cent...In this work, an analysis of the generation, composition and management of the urban solid waste in Mexico and its relation to greenhouse gas emissions is described;as well a case study in Morelos, a state in the central region of the country. Data were collected from the scientific literature and existing data bases at state and national levels. In addition, the emissions of greenhouse gas were calculated for a period of 14 years, using the Intergovernmental Panel on Climate Change (IPCC) methodology. The municipal solid waste data collected from 1998 to 2012 reveal an increase in the amount of waste generated in Mexico and in Morelos (38% and 43%, respectively), which have been influenced by the urbanization process and the population increase. According to the official data, the composition of the urban solid waste in Mexico, is mostly organic matter (50%), represented by food and garden residues, as well as paper and cardboard (near to 14%). While in Morelos, the percentages of generation for these materials are 44% and 9%, respectively. The management of the urban waste mainly consists of house collection, principally in metropolitan zones and medium and small cities, representing 78.7% in Mexico and 89.2% in Morelos. The second way to eliminate the solid wastes is open burning (mostly in semi-urban and rural areas), representing 14.5% and 6.7% for Mexico and Morelos, respectively. During this period, the nationwide greenhouse gas emissions derived from solid waste management (SWM) increased by 180%, while in Morelos, an increase of 42.5% was calculated. Thus, the population increment and urbanization process were correlated with the rise in the amount of residues generated in Mexico and Morelos.展开更多
This research was based on the manufacture of new composite materials that offer technological possibilities in the development of new devices with greater efficiency. Electrospinning was used to form nylon 66/-tetra-...This research was based on the manufacture of new composite materials that offer technological possibilities in the development of new devices with greater efficiency. Electrospinning was used to form nylon 66/-tetra-(para-aminophenyl) porphyrin (H2T(p-NH2)PP)/graphene oxide (GO) composite film. Graphene oxide coatings were obtained from graphite, through mechanical exfoliation followed by calcination and ultrasonic agitation in an oxidant solution. These samples were characterized under SEM, FTIR, Raman spectroscopy, UV-vis and R-X techniques. On the other hand, H2T(p-NH2)PP was synthesized in two steps?process by the Rothemun reaction and the Adler Method and it was integrated within nylon polyamide fibers by direct addition of a hexamethylenediamine/adipoyl chloride reactant mixture. The polymerization of the nylon/H2T(p-NH2)PP species occurs in such a way that it starts or ends on the four peripherals-NH2 groups, connected and located in the same molecular plane of H2T(p-NH2)PP, forming nylon chains at the periphery of the macrocycle. The association of GO with nylon/H2T(p-NH2)PP fibers is performed by dipole-dipole interaction and hydrogen bonding. To take advantage of the properties of these materials, they were combined as a ternary composite.展开更多
The effect of IB element additions [Ag] on the corrosion behavior of AlZn alloy has been investigated. The potentiodynamic polarization curves revealed that the corrosion behavior of SSAl, SSZn and AgZn3 phases was si...The effect of IB element additions [Ag] on the corrosion behavior of AlZn alloy has been investigated. The potentiodynamic polarization curves revealed that the corrosion behavior of SSAl, SSZn and AgZn3 phases was significantly influenced by IB element content. The electrochemical investigations showed that the corrosion rate increased with the IB-element additions. Furthermore, it was also evidenced the formation of a passive layer for the highest Ag content alloys;the passivity of this layer could be broken due to the presence of the intermetallic compound (IMCs) AgZn3.展开更多
There is an increased interest in renewable forms of energy across the world,with solar energy being one of the most promising forms.Over the last couple of years,we have developed the MET(MicroEquipment Technology).A...There is an increased interest in renewable forms of energy across the world,with solar energy being one of the most promising forms.Over the last couple of years,we have developed the MET(MicroEquipment Technology).As an application of the MET,we selected the task of production of solar concentrators.Different types of solar concentrators with flat mirrors were developed and prototypes of these solar concentrators(approximately 1 m in diameter)were made.The proposed solar concentrators were developed on the basis of concentrators patented in Mexico,Spain,and USA.It may be possible to install these concentrators on horizontal roofs of buildings.However,installing them on agricultural fields has become the new trend.As an example,we propose to use them in the potato fields in Canada to obtain dual advantages such as for electrical energy generation and for the minimal loss of agricultural harvest.The second example was analyzed for bean fields,in Mexico.In this paper,we describe the main results in regard to microequipment development for solar concentrator production,several prototypes of solar concentrators with flat mirrors and their co-location and agricultural fields.展开更多
In the framework of the Thomas–Fermi(TF) approach, a model for the p-type double-δ-doped(DDD) system in Ga As is presented. This model, unlike other works in the literature, takes into account that the Poisson equat...In the framework of the Thomas–Fermi(TF) approach, a model for the p-type double-δ-doped(DDD) system in Ga As is presented. This model, unlike other works in the literature, takes into account that the Poisson equation associated with the system is nonlinear. The electronic structure is calculated for heavy and light holes. The changes in the electronic structure result of the distance d between the doped layers are studied. In particular, the relative absorption coefficient as well as the relative refractive index change is calculated as a function of the incident photon energy for heavy holes. The effect of the interlayer distance exhibits, in the absorption coefficient, a red shift of the peak position and a decrease in amplitude when the distance increases. In addition, the relative refractive index change node has a red shift as well as the interlayer distance increases. The calculations show that the effect of the separation between layers has a greater influence on the linear terms. These results are very important for theoretical calculations and engineering of optical and electronic devices based in δ-doped Ga As.展开更多
Objective:To assess the relaxant effect of several organic extracts obtained from Agastache mexicana(A.mexicana),Cochlospermum vitifolium(C.vitifolium),Cordia morelosana(C.morelosana),Lepechinia caulescens(L.caulescen...Objective:To assess the relaxant effect of several organic extracts obtained from Agastache mexicana(A.mexicana),Cochlospermum vitifolium(C.vitifolium),Cordia morelosana(C.morelosana),Lepechinia caulescens(L.caulescens)and Talauma mexicana(71 mexicana)used in Mexican traditional medicine for the treatment of several diseases.Methods:Extracts were obtained by maceration at room temperature using hexane,dicliloromethane and methanol for each plant material.The organic extracts were evaluated ex vivo to determine their relaxant activity on the contractions induced by carbaehol(cholinergic receptor agonist,1μmol/L in isolated rat tracheal rings.Results:A total of 15 extracts were evaluated(three for each species).All test samples showed significant relaxant effect,in a concentration-dependent manner,on the contractions induced by 1μmol/L carbachol,with exception of extracts from C.morelosana.Active extracts were less potent than theophylline[phosphodiesterase inhibitor,EC_(50):(28.79±0.82)μg/mL]that was used as positive control.Concentration-response curves revealed that the extracts with more significant effects were dichloromethanic extracts of T.mexhxma[E_(max):(103.03±3.32)%and EC_(50):(159.39±3.72)μg/mL)and C.vitifolium[Emax:(106.58±2.42)%and EC_(50):(219.54±7.61)μg/mL].Finally,hexanic and dichloromethanic extracts from A.mexicana were fully effective but less potent than T.mexicana,and C.vitifolium.Conclusions:Less polar extracts obtained from A.mexicana,71 mexicana and C.vitifolium exhibited greater relaxant effect on tracheal rat rings,which allows us to suggest them as sources for the isolation of bioactive molecules with potential therapeutic value in the treatment of asthma.展开更多
Quercus rugosa and Q.laurina are species that presents a wide geographical distribution range in temperate forests of Mexico. Oak canopies contain a considerable portion of arthropod diversity and the arthropods fauna...Quercus rugosa and Q.laurina are species that presents a wide geographical distribution range in temperate forests of Mexico. Oak canopies contain a considerable portion of arthropod diversity and the arthropods fauna fulfill a wide variety of ecological roles. We examined the effect of oak species and seasonal changes on some community structure parameters (diversity,composition,similarity,biomass,rare species,and density of arthropod fauna) of canopy arthropods. In total,40 oak canopies were fogged during rainy and dry season. A total of 614 identified arthropod morphospecies were recognized belonging to 22 orders associated with tree canopies. A separation of host tree species during both seasons,suggesting a different community structure on host plants species was demonstrated by the principal component analyses (PCA),therefore,differences between oak species results in phenotypes that structure the composition of the arthropod community. Q.laurina registered the highest densities,diversity index and number of rare species in comparison with Q.rugosa. While arthropod biomass showed an inverse pattern. Trees more close to one another (spatial distance) register a more similar canopy arthropod fauna. This study suggests that the trees of Q.laurina could act as a center of biodiversity by the accumulation of arthropod fauna with a considerable number of rare species,which presents wide ecological roles or is involved in critical processes that maintain forest ecosystems.展开更多
Determination of the negative ion number density of O2 and O in a DC discharge of oxygen plasma was made employing Langmuir probe in conjunction with eclipse laser photo- detachment technique. The temporal evolution o...Determination of the negative ion number density of O2 and O in a DC discharge of oxygen plasma was made employing Langmuir probe in conjunction with eclipse laser photo- detachment technique. The temporal evolution of the extra electrons resulting from the photo- detachment of O2- and O- were used to evaluate the negative ion number density. The ratio of O2 number density to O varied from 0.03 to 0.22. Number density of both O~ and O increased with increasing power and decreased as the pressure was increased. Electron number density was evaluated from the electron energy distribution function (EEDF) using the I-V recorded characteristic curves. Electron temperature between 2 and 2.7 eV were obtained. Influence of the 02(al△g) metastable state is discussed.展开更多
This paper presents the numerical comparison in the solution of the hyperbolic transport Equation that models the heat flux in thermoelectric materials at nanometric length scales when the wave propagation of heat dom...This paper presents the numerical comparison in the solution of the hyperbolic transport Equation that models the heat flux in thermoelectric materials at nanometric length scales when the wave propagation of heat dominates the diffusive transport described by Fourier’s law. The widely used standard finite difference method fails in well-reproducing some of the physics presented in such systems at that length scale level. As an alternative, the spectral methods assure a well representation of wave behavior of heat given their spectral convergence.展开更多
In the Central Desert of northern Baja California, blue fan palm populations (Brahea armata) are found as isolated oases on mountaintops and along canyons with ephemeral flow conditions. Here, the effect of the intera...In the Central Desert of northern Baja California, blue fan palm populations (Brahea armata) are found as isolated oases on mountaintops and along canyons with ephemeral flow conditions. Here, the effect of the interaction between the larva of an endemic moth, Litoprosopus bajaensis, and this endemic blue fan palm was documented for the first time. We registered the phenology of palms by counting the number of shoots with flowers or fruits, assessing their damage and calculating the reproductive success per individual palm within three populations: San Pedro Martir, Catavi?a, and La Libertad. Palm populations were severely impacted by this larva, causing high damage to the inflorescences. No differences were found in the number of inflorescence stems produced and damaged among study sites;but the reproductive success of palms was significantly higher in Catavi?a than in the other sites during the entire sampling period, and consequently an important proportion of stems escaped from the herbivore predation. We suggest that differences among sites may be explained by the fact that Catavi?a is the only alluvial canyon and can be considered an area of high nutrient uptake, resource availability, and rooting depths. In contrast the other two are bedrock canyons, where water runs intensely, sweeping away great portions of the nearby vegetation. Catavi?a received the highest precipitation during the winter season of 2010 allowing a continuous production of inflorescence stems and fruits. This preliminary study reveals a new endemic interaction, it occurrence at population and regional levels, and highlights the role of desert oases as resource patches and connectivity pathways for mobile insects. Finally, it also highlights the effects of different water flow dynamics and water pulses in providing an opportunity window of escape from predation for host plant species living in desert environments.展开更多
文摘In two contrasting agricultural ecohabitats (agrohabitats) in the avocado production area in the municipality of Cuernavaca, Morelos, an analysis of nutrimental status, soil fertility and water quality was conducted to measure soil fertility levels and to determine the nutrimental state of the trees. The “Hass” variety avocado groves studied had an average age of 8 years;the first grove was planted in an acrisol soil (1700 to 1900 meters above mean sea level [mamsl]);the second, in an andosol soil (1200 to 1700 mamsl). In each agrohabitat, tests were performed to determine the soil’s physical and chemical characteristics. The physical and chemical characteristics of the soils of this zone differ as do the nutrimental states of the avocado trees in the two agrohabitats. The trees showed excessive concentration of Ca, Fe, S, Z and Mg. The indices of Deviation from Optimal Percentage (DOP) in the two agrohabitats showed different nutrimental requirements;nevertheless, they were low and very near to zero, 14.218 and 13.350 respectively. The water used for the agricultural irrigation was low in salinity and sodium content and thus may be used for the agricultural irrigation without restrictions.
文摘The objective of the present work is modeling the mobility habitus in the public transport system with low Co2 emission mechanics in the center of Mexico.In this sense,a documentary work was carried out with a review of sources indexed to national repositories,using the Delphi technique for the content analysis and the specification of the model.A study was conducted with a selection of 100 students to establish the reliability,linearity,sphericity,adequacy,and validity of an instrument from which a relationship of dependence between income and mobility habitus was observed.The limits of the search,selection,and processing of information are recognized,and it is recommended to extend the research to international repositories,as well as to employ a more sophisticated technique.
文摘It is very important for the car users to have several communication systems and many antennas, which respond to the demands of aesthetics and efficiency. In this case, it is necessary to consider different types of materials and geometries. Among the automobile systems, the navigation systems are found, which are formed by a Global Position System (GPS), with a pre-charged base of maps and highways in order to locate the vehicle. For the reception of the GPS signals, circularly polarized patch antennas are used, which must be designed to operate at 1.57 GHz. This work is focused on the analysis of a circular antenna performance, designed for GPS, by means of the simulation of the following cases: antenna without radome, antenna with acrylic radome, and, finally, antenna on the roof of an automobile, considering the effect of the complete chassis. A Basic, a Simplified and a More Simplified Advanced Car Models (BCM, SACM, and MSACM) were used in order to analyze the chassis shape. The simulations were carried out with the software FEKO. The fabrication and experimental and practical tests are also presented.
文摘Results of a soil radon survey accomplished by 2 different methods during 2 different periods in the area of Tlamacas Mountain are presented. The first study, carried out from 15-APR-2010 to 09-MAY-2010 in 30 measurement sites by means of CR39 solid state nuclear detectors, shows 2 active zones with intensive radon emanation with a characteristic dimension of about 300 meters located in the northwestern and western parts of the Mountain. The second survey, made on 05-JUL-2011 in 23 measurement sites with 10 min sampling by a SARAD RTM 1688 Radon/Thoron monitor, in contrast, revealed a sizeable area depleted in radon and 3 active areas of increased radon release in the lateral Mountain sides. These observed phenomena strengthen our assumption about the presence of an active geological structure in Tlamacas Mountain connected with a geodynamical processes in volcano Popocatepetl.
文摘Ultrasound-assisted pretreatment under mild operating conditions has been investigated for intensification of delignification to facilitate the obtaining of ethyl levulinate from biomass. The effect of pH (2 - 12), temperature (30°C - 70°C) and pretreatment time (0 - 120 minutes) has been studied for different biomass samples. The most favorable conditions were basic pH, temperature of 70°C and pretreatment time of 2 h, obtaining values of delignification near 80 percent. The ethyl levulinate is obtained in microwave directly via from samples before and after delignification and analyzed for GC-MS. The results evidenced better yields for the delignified samples.
文摘High blood pressure is the main risk factor for cardiovascular diseases, it affects many people worldwide and is a public health problem. This study explored the acute and chronic actions of a mixture of turmeric (95% curcumin) plus black pepper (95% piperine) extracts, in the blood pressure pattern in spontaneously hypertensive rats (SHR) along they age. For the acute study male adult (4 - 7 months old) SHR and their control Wistar Kyoto rats (WKY) were used. A single oral dose of the mixture of turmeric/black pepper extracts (200 mg/2mg, respectively) suspension was administered. Tail-cuff was used to determine blood pressure during 180 min. For the chronic study, young (1-month-old) male SHR and their control WKY rats were fed with standard chow, or standard chow combined with cocoa, or combined with cocoa plus the mixture of turmeric/black pepper extracts;tail-cuff was used to determine blood pressure once a week, along 12 weeks. In a second chronic assay adult (5 months old) male SHR and their control WKY rats were fed with standard chow, or standard chow combined with cocoa, or combined with cocoa plus the mixture of turmeric/black pepper extracts;tail-cuff was used to determine blood pressure once a week, along 12 weeks. In all three studies, a decrease in systolic, diastolic and mean blood pressure was observed, being higher in SHR and negligible in WKY rats. The mixture of turmeric/black pepper extracts showed antihypertensive actions in SHR rats with no effect on WKY rats. The mixture delayed the onset of hypertension in young SHR rats.
文摘A novel method of renormalization called Pacman renormalization allows us to study (unicritical) Siegel functions through Pacman-type functions. It has been used to investigate the Siegel parameters with combinatorially periodic rotation number in the main cardioid of the Mandelbrot set. It is already known that it can be defined a Pacman renormalization operator such that for Siegel pacmen, with combinatorially periodic rotation numbers, the operator is compact, analytic and has a unique fixed point, at which it is hyperbolic with one-dimensional unstable manifold. In this paper we observe that this Pacman renormalization operator is compact and analytic at any Siegel Pacman or Siegel map with combinatorially bounded rotation number. This allows us to define a renormalization operator on the hybrid classes of the standard Siegel pacmen to which we built its horseshoe where the operator is topologically semiconjugated to the left shift on the space of bi-infinite sequences of natural numbers bounded by some constant.
文摘There are different types of pollutants that are harmful to the environment, including smog, chemicals that are dumped into rivers, scrap tires, etc. The latter have the particularity that it is not possible to recycle them to manufacture new tires. In the present work, hydraulic concrete plates added with waste tire rubber were manufactured to modify their sound absorption capacity. It was found that the rubber additions produce changes in the density of the material and in the sound absorption capacity. When the material is exposed to high-frequency sounds that correspond to high-pitched sounds, its absorption capacity increases. On the contrary, when the test frequency is low, that is, bass sounds, the sound absorption capacity decreases. The results obtained in this work suggest that the proposed mixtures are suitable for the possible manufacture of acoustic insulating shields.
文摘An ultrasound-assisted heterogeneous catalytic oxidation process was applied to eliminate sulfur from commercial diesel fuel oil.The studied variables were catalyst concentration,type of catalyst(homogeneous or heterogeneous),oxidizing agent concentration,and the application of ultrasound energy.Supported catalysts were prepared by impregnation of coal fly ash with an iron(Ⅱ)sulfate aqueous solution using ultrasound energy.After drying,the catalyst was calcined at 500℃for 4 h.The oxidizing agent was hydrogen peroxide.Ultrasound energy was applied with a frequency of 47 kHz and an intensity of 147 W.Ethanol was employed for extracting the oxidized compounds from the hydrocarbon mixture.Coal fly ash and ethanol were used with the purpose of applying low-cost raw materials in chemical processes.It was found that under the studied conditions,increasing oxidizing agent concentration and the application of ultrasound energy can enhance the sulfur removal from commercial diesel fuel oil.Catalyst concentration did not play a significant role in the process.Similar results were obtained using homogeneous or heterogeneous catalyst,which is important since the heterogeneous catalyst could be recovered,reactivated,and used in many cycles.
文摘In this work, the estimation of crack initiation life of a hydraulic Francis turbine runner is presented. The life prediction is based on the local strain approach to predict the initiation life. First, the analysis is carried out in air and in water condition and the runner’s natural frequencies were calculated using the finite element (FE) method. The analysis in air is compared with experimental analysis in order to have a representative model of real runner and subsequently the numerical analysis was perform in water. In the case of the runner immersed in water, the added mass effect due to the fluid structure interaction (FSI) is considered. Second, the static and dynamic stresses were calculated according to life estimation. For the calculation of static stresses, the pressure distribution of water and the centrifugal forces were applied to the runner. The dynamic stresses were estimated for interactions between the guide vane and the runner. Lastly, the estimation of the crack initiation life of the runner was obtained.
文摘In this work, an analysis of the generation, composition and management of the urban solid waste in Mexico and its relation to greenhouse gas emissions is described;as well a case study in Morelos, a state in the central region of the country. Data were collected from the scientific literature and existing data bases at state and national levels. In addition, the emissions of greenhouse gas were calculated for a period of 14 years, using the Intergovernmental Panel on Climate Change (IPCC) methodology. The municipal solid waste data collected from 1998 to 2012 reveal an increase in the amount of waste generated in Mexico and in Morelos (38% and 43%, respectively), which have been influenced by the urbanization process and the population increase. According to the official data, the composition of the urban solid waste in Mexico, is mostly organic matter (50%), represented by food and garden residues, as well as paper and cardboard (near to 14%). While in Morelos, the percentages of generation for these materials are 44% and 9%, respectively. The management of the urban waste mainly consists of house collection, principally in metropolitan zones and medium and small cities, representing 78.7% in Mexico and 89.2% in Morelos. The second way to eliminate the solid wastes is open burning (mostly in semi-urban and rural areas), representing 14.5% and 6.7% for Mexico and Morelos, respectively. During this period, the nationwide greenhouse gas emissions derived from solid waste management (SWM) increased by 180%, while in Morelos, an increase of 42.5% was calculated. Thus, the population increment and urbanization process were correlated with the rise in the amount of residues generated in Mexico and Morelos.
文摘This research was based on the manufacture of new composite materials that offer technological possibilities in the development of new devices with greater efficiency. Electrospinning was used to form nylon 66/-tetra-(para-aminophenyl) porphyrin (H2T(p-NH2)PP)/graphene oxide (GO) composite film. Graphene oxide coatings were obtained from graphite, through mechanical exfoliation followed by calcination and ultrasonic agitation in an oxidant solution. These samples were characterized under SEM, FTIR, Raman spectroscopy, UV-vis and R-X techniques. On the other hand, H2T(p-NH2)PP was synthesized in two steps?process by the Rothemun reaction and the Adler Method and it was integrated within nylon polyamide fibers by direct addition of a hexamethylenediamine/adipoyl chloride reactant mixture. The polymerization of the nylon/H2T(p-NH2)PP species occurs in such a way that it starts or ends on the four peripherals-NH2 groups, connected and located in the same molecular plane of H2T(p-NH2)PP, forming nylon chains at the periphery of the macrocycle. The association of GO with nylon/H2T(p-NH2)PP fibers is performed by dipole-dipole interaction and hydrogen bonding. To take advantage of the properties of these materials, they were combined as a ternary composite.
文摘The effect of IB element additions [Ag] on the corrosion behavior of AlZn alloy has been investigated. The potentiodynamic polarization curves revealed that the corrosion behavior of SSAl, SSZn and AgZn3 phases was significantly influenced by IB element content. The electrochemical investigations showed that the corrosion rate increased with the IB-element additions. Furthermore, it was also evidenced the formation of a passive layer for the highest Ag content alloys;the passivity of this layer could be broken due to the presence of the intermetallic compound (IMCs) AgZn3.
文摘There is an increased interest in renewable forms of energy across the world,with solar energy being one of the most promising forms.Over the last couple of years,we have developed the MET(MicroEquipment Technology).As an application of the MET,we selected the task of production of solar concentrators.Different types of solar concentrators with flat mirrors were developed and prototypes of these solar concentrators(approximately 1 m in diameter)were made.The proposed solar concentrators were developed on the basis of concentrators patented in Mexico,Spain,and USA.It may be possible to install these concentrators on horizontal roofs of buildings.However,installing them on agricultural fields has become the new trend.As an example,we propose to use them in the potato fields in Canada to obtain dual advantages such as for electrical energy generation and for the minimal loss of agricultural harvest.The second example was analyzed for bean fields,in Mexico.In this paper,we describe the main results in regard to microequipment development for solar concentrator production,several prototypes of solar concentrators with flat mirrors and their co-location and agricultural fields.
基金Project supported by PISA 2016–1 UJAT and PRODEP Folio UJAT-245 of México
文摘In the framework of the Thomas–Fermi(TF) approach, a model for the p-type double-δ-doped(DDD) system in Ga As is presented. This model, unlike other works in the literature, takes into account that the Poisson equation associated with the system is nonlinear. The electronic structure is calculated for heavy and light holes. The changes in the electronic structure result of the distance d between the doped layers are studied. In particular, the relative absorption coefficient as well as the relative refractive index change is calculated as a function of the incident photon energy for heavy holes. The effect of the interlayer distance exhibits, in the absorption coefficient, a red shift of the peak position and a decrease in amplitude when the distance increases. In addition, the relative refractive index change node has a red shift as well as the interlayer distance increases. The calculations show that the effect of the separation between layers has a greater influence on the linear terms. These results are very important for theoretical calculations and engineering of optical and electronic devices based in δ-doped Ga As.
基金financed by a grant from"Apoyo a la Mejora del Perfil Individual del profesorado de tiempo completo.(Fondo para la Consolidacin de las Universidades Públicas Estatales y con Apoyo Solidario Ejereicio 2009)"Faculty of Pharmacy budgets(2010 and 2011)grants from CONACyT-CIENCIA BASICA CB-2011-01(167044)
文摘Objective:To assess the relaxant effect of several organic extracts obtained from Agastache mexicana(A.mexicana),Cochlospermum vitifolium(C.vitifolium),Cordia morelosana(C.morelosana),Lepechinia caulescens(L.caulescens)and Talauma mexicana(71 mexicana)used in Mexican traditional medicine for the treatment of several diseases.Methods:Extracts were obtained by maceration at room temperature using hexane,dicliloromethane and methanol for each plant material.The organic extracts were evaluated ex vivo to determine their relaxant activity on the contractions induced by carbaehol(cholinergic receptor agonist,1μmol/L in isolated rat tracheal rings.Results:A total of 15 extracts were evaluated(three for each species).All test samples showed significant relaxant effect,in a concentration-dependent manner,on the contractions induced by 1μmol/L carbachol,with exception of extracts from C.morelosana.Active extracts were less potent than theophylline[phosphodiesterase inhibitor,EC_(50):(28.79±0.82)μg/mL]that was used as positive control.Concentration-response curves revealed that the extracts with more significant effects were dichloromethanic extracts of T.mexhxma[E_(max):(103.03±3.32)%and EC_(50):(159.39±3.72)μg/mL)and C.vitifolium[Emax:(106.58±2.42)%and EC_(50):(219.54±7.61)μg/mL].Finally,hexanic and dichloromethanic extracts from A.mexicana were fully effective but less potent than T.mexicana,and C.vitifolium.Conclusions:Less polar extracts obtained from A.mexicana,71 mexicana and C.vitifolium exhibited greater relaxant effect on tracheal rat rings,which allows us to suggest them as sources for the isolation of bioactive molecules with potential therapeutic value in the treatment of asthma.
文摘Quercus rugosa and Q.laurina are species that presents a wide geographical distribution range in temperate forests of Mexico. Oak canopies contain a considerable portion of arthropod diversity and the arthropods fauna fulfill a wide variety of ecological roles. We examined the effect of oak species and seasonal changes on some community structure parameters (diversity,composition,similarity,biomass,rare species,and density of arthropod fauna) of canopy arthropods. In total,40 oak canopies were fogged during rainy and dry season. A total of 614 identified arthropod morphospecies were recognized belonging to 22 orders associated with tree canopies. A separation of host tree species during both seasons,suggesting a different community structure on host plants species was demonstrated by the principal component analyses (PCA),therefore,differences between oak species results in phenotypes that structure the composition of the arthropod community. Q.laurina registered the highest densities,diversity index and number of rare species in comparison with Q.rugosa. While arthropod biomass showed an inverse pattern. Trees more close to one another (spatial distance) register a more similar canopy arthropod fauna. This study suggests that the trees of Q.laurina could act as a center of biodiversity by the accumulation of arthropod fauna with a considerable number of rare species,which presents wide ecological roles or is involved in critical processes that maintain forest ecosystems.
基金financed by CONACy T with contract#41072-F,PRODEPthe Programa Integral de Fortalecimiento Institucinal-2
文摘Determination of the negative ion number density of O2 and O in a DC discharge of oxygen plasma was made employing Langmuir probe in conjunction with eclipse laser photo- detachment technique. The temporal evolution of the extra electrons resulting from the photo- detachment of O2- and O- were used to evaluate the negative ion number density. The ratio of O2 number density to O varied from 0.03 to 0.22. Number density of both O~ and O increased with increasing power and decreased as the pressure was increased. Electron number density was evaluated from the electron energy distribution function (EEDF) using the I-V recorded characteristic curves. Electron temperature between 2 and 2.7 eV were obtained. Influence of the 02(al△g) metastable state is discussed.
文摘This paper presents the numerical comparison in the solution of the hyperbolic transport Equation that models the heat flux in thermoelectric materials at nanometric length scales when the wave propagation of heat dominates the diffusive transport described by Fourier’s law. The widely used standard finite difference method fails in well-reproducing some of the physics presented in such systems at that length scale level. As an alternative, the spectral methods assure a well representation of wave behavior of heat given their spectral convergence.
文摘In the Central Desert of northern Baja California, blue fan palm populations (Brahea armata) are found as isolated oases on mountaintops and along canyons with ephemeral flow conditions. Here, the effect of the interaction between the larva of an endemic moth, Litoprosopus bajaensis, and this endemic blue fan palm was documented for the first time. We registered the phenology of palms by counting the number of shoots with flowers or fruits, assessing their damage and calculating the reproductive success per individual palm within three populations: San Pedro Martir, Catavi?a, and La Libertad. Palm populations were severely impacted by this larva, causing high damage to the inflorescences. No differences were found in the number of inflorescence stems produced and damaged among study sites;but the reproductive success of palms was significantly higher in Catavi?a than in the other sites during the entire sampling period, and consequently an important proportion of stems escaped from the herbivore predation. We suggest that differences among sites may be explained by the fact that Catavi?a is the only alluvial canyon and can be considered an area of high nutrient uptake, resource availability, and rooting depths. In contrast the other two are bedrock canyons, where water runs intensely, sweeping away great portions of the nearby vegetation. Catavi?a received the highest precipitation during the winter season of 2010 allowing a continuous production of inflorescence stems and fruits. This preliminary study reveals a new endemic interaction, it occurrence at population and regional levels, and highlights the role of desert oases as resource patches and connectivity pathways for mobile insects. Finally, it also highlights the effects of different water flow dynamics and water pulses in providing an opportunity window of escape from predation for host plant species living in desert environments.