Objective: This work compares the occlusive effect and the penetration enhancement ability of solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC), through in vitro skin. Methods: SLN and NLC were p...Objective: This work compares the occlusive effect and the penetration enhancement ability of solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC), through in vitro skin. Methods: SLN and NLC were prepared by high shear homogenization and characterized by size, polydispersity index, zeta potential, morphology and physical stability. Occlusive effect was assessed by an in vitro test and by measuring TEWL using pig skin. Skin treated with the lipid carriers was visualized by SEM. A penetration test through skin, followed by tape stripping, was carried out using Nile red as a marker. Results: SLN (200 ± 6 nm) and NLC (192 ± 11 nm) were obtained. An occlusion factor of 36% - 39% was observed for both systems, while a reduction in TEWL of 34.3% ± 14.8% and 26.2% ± 6.5% was seen after treatment with SLN and NLC, respectively. SEM images showed a film formed by the lipid carriers, responsible for the occlusion observed. No differences were found between the occlusive effect produced by SLN and NLC in both tests. NLC allowed the penetration of a greater amount of Nile red than SLN: 4.7 ± 1.3 μg and 1.7 ± 0.4 μg, respectively. Conclusion: Both carriers form a film on the skin, providing an occlusive effect with no differences between these two systems. The penetration of a marker (Nile red) into the stratum corneum was quite higher for NLC than for SLN, suggesting an influence of the composition of these particles on their penetration enhancing ability.展开更多
Determining climatic and physiographic variables in Mexico’s major ecoregions that are limiting to biodiversity and species of high conservation concern is essential for their conservation.Yet,at the national level t...Determining climatic and physiographic variables in Mexico’s major ecoregions that are limiting to biodiversity and species of high conservation concern is essential for their conservation.Yet,at the national level to date,few studies have been performed with large data sets and crossconfirmation using multiple statistical analyses.Here,we used 25 endemic,rare and endangered species from 3610 sampling points throughout Mexico and 25 environmental attributes,including average precipitation for different seasons of the year,annual dryness index,slope of the terrain;and maximum,minimum and average temperatures to test our hypothesis that these species could be assessed with the same weight among all variables,showing similar indices of importance.Our results using principal component analysis,covariation analysis by permutations,and random forest regression showed that summer precipitation,length of the frost-free period,spring precipitation,winter precipitation and growing season precipitation all strongly influence the abundance of tropical species.In contrast,annual precipitation and the balance at different seasons(summer and growing season)were the most relevant variables on the temperate region species.For dry areas,the minimum temperature of the coldest month and the maximum temperature of the warmest month were the most significant variables.Using these different associations in different climatic regions could support a more precise management and conservation plan for the preservation of plant species diversity in forests under different global warming scenarios.展开更多
The present study was conducted to evaluate the impact of bimetallic nanoparticles(NPs)of copper(Cu)and zinc(Zn)from Crotalaria longirostrata on the insect mortality and cell viability of Phenacoccus solenopsis.The bi...The present study was conducted to evaluate the impact of bimetallic nanoparticles(NPs)of copper(Cu)and zinc(Zn)from Crotalaria longirostrata on the insect mortality and cell viability of Phenacoccus solenopsis.The biosynthesis of bimetallic nanoparticles(Cu/Zn-NPs)from C.longirostrata was confirmed by the presence of a single peak around 378 nm.The hydrodynamic diameter of the Cu/Zn nanoparticles varied from 59 to 119 nm and their zeta potential was found to be−30.90 mV.The EDX analysis showed a strong signal for Cu and Zn(8 and 8.6 keV,respectively).The Cu/Zn-NPs showed an effective insecticide activity against P.solenopsis with 63%of insect mortality after 96 h treatment.However,further studies about nanotoxicity of Cu/Zn-NPs from C.longirostra are needed to reveal the exact mechanism of nanoparticles toxicity in insects.展开更多
Biodegradable magnesium alloys are promising candidates for temporary fracture fixation devices in orthopedics;nevertheless,its fast degradation rate at the initial stage after implantation remains as one of the main ...Biodegradable magnesium alloys are promising candidates for temporary fracture fixation devices in orthopedics;nevertheless,its fast degradation rate at the initial stage after implantation remains as one of the main challenges to be resolved.ZrO_(2)-based coatings to reduce the degradation rate of the Mg-implants are an attractive solution since they show high biocompatibility and stability.In this work,the degradation,cytotoxicity,and antibacterial performance of ZrO_(2)thin films deposited by magnetron sputtering on a Mg-Zn-Ca alloy was evaluated.Short-term degradation of ZrO_(2)-coated and uncoated samples was assessed considering electrochemical techniques and H_(2)evolution(gas chromatography).Additionally,long term degradation was assessed by mass-loss measurements.The results showed that a 380 nm ZrO_(2)coating reduces the degradation rate and H_(2)evolution of the alloy during the initial 3 days after immersion but allows the degradation of the bare alloy for the long-term.The ZrO_(2)coating does not compromise the biocompatibility of the alloy and permits better cell adhesion and proliferation of mesenchymal stem cells directly on its surface,in comparison to the bare alloy.Finally,the ZrO_(2)coating prevents the adhesion and biofilm formation of S.aureus.展开更多
The essential oils obtained by hydrodistillation from leaves and flowers of Montanoa speciosa collected in southeastern Mexico (Yucatan) were analyzed by GC-MS. A total of 71 and 79 components, representing 98.44% and...The essential oils obtained by hydrodistillation from leaves and flowers of Montanoa speciosa collected in southeastern Mexico (Yucatan) were analyzed by GC-MS. A total of 71 and 79 components, representing 98.44% and 97.69% of the leaf and flower oils, respectively, were characterized. The main constituents found were β-caryophyllene (20.73%, 17.95%), δ-cadinene (9.88%, 9.28%), caryophyllene oxide (9.48%, 8.68%), and germacrene D (6.94%, 5.85%). The essential oils were screened for their antioxidant potentials by DPPH assay. The leaves oil exhibited higher DPPH scavenging capability (72.85 ± 0.28 mmol TE/g essential oil and 147.83 ± 0.41 mg/mL Vit C/g essential oil) than the floral oil (68.43 ± 0.10 mmol TE/g essential oil and 131.59 ± 0.87 mg/mL Vit C/g essential oil).展开更多
Recently, studies were initiated to investigate the metagenome, which represents the genomes of cultured and uncultured microbes, as a rich source for isolation of many novel genes. The meta-genomic approach originate...Recently, studies were initiated to investigate the metagenome, which represents the genomes of cultured and uncultured microbes, as a rich source for isolation of many novel genes. The meta-genomic approach originated from the molecular analysis of microbial communities, which revealed that the majority of microorganisms in nature were not cultivable by standard culturing techniques. Therefore, most microorganisms in nature have not been characterized. Although numerous methods have been reported for direct DNA isolation and purification from microorganisms in soil, the sample preparation procedures and experimental conditions used in different studies vary widely. Soils are therefore one of the most challenging environmental matrices from which to obtain microbial DNA that will support PCR. The Papaloapan River is the second largest river basin in México. For the climatic conditions of this region, there is great diversity in plants, animals and microorganisms. In the Papaloapan region different fruits are grown, however, the main crops are sugarcane and pineapple. In this work the extraction of DNA from soils of sugarcane cultivation was performed. We used PCR tests to assess the quality of DNA extracted from soil by amplifying the 16S rDNA gene. Changes in both protocols were performed;satisfactory results were obtained as to the quality of DNA and gene amplification. These results will allow continuing the metagenomic studies, such as sequencing, library construction and identification of enzymes cellulase and amylase activity. It is the first time these studies were performed in the Papaloapan region.展开更多
The cellular strategy leading to formation of neuronal circuits in the rodent barrel cortex is still a matter of controversy. Both selective and constructive mechanisms have been proposed. The selective mechanism invo...The cellular strategy leading to formation of neuronal circuits in the rodent barrel cortex is still a matter of controversy. Both selective and constructive mechanisms have been proposed. The selective mechanism involves an overproduction of neuronal processes and synapses followed by activity dependent pruning. Conversely, a constructive mechanism would increase the number of axons, dendrites, and synapses during development to match functionality. In order to discern the contributions of these two mechanisms in establishing a neuronal circuit in the somatosensory cortex, morphometric analysis of dendritic and axonal arbor growth was performed. Also, the number of synapses was followed by electron microscopy during the first month of life. We observed that axonal and dendritic arbors retracted distal branches, and elongated proximal branches, resulting in increased arbor complexity. This neuronal remodeling was accompanied by the steady increase in the number of synapses within barrel hollows. Similarly, the content of molecular markers for dendrites, axons and synapses also increased during this period. Finally, cytochrome oxidase activity rose with age in barrels indicating that the arbors became more complex while synapse density and metabolic demands increased. Our results support the simultaneous use of both selective and constructive mechanisms in establishing the barrel cortex circuitry.展开更多
Quorum sensing is a chemical communication process that bacteria use to regulate collective behaviors. In Gram-positive bacteria, oligopeptides (called autoinducers) are the signaling molecules to elicit quorum sensin...Quorum sensing is a chemical communication process that bacteria use to regulate collective behaviors. In Gram-positive bacteria, oligopeptides (called autoinducers) are the signaling molecules to elicit quorum sensing. In Bacillus thuringiensis, NprR is a transcriptional regulator whose activity depends on the NprX signalling peptide. Bacillus thuringiensis is closely related to Bacillus cereus and Bacillus anthracis. The principal difference between them is that Bacillus thuringiensis is the only one that produced Cry protein. The aim of this study is to explore the relation of nprR and 16S rRNA genes in Bacillus thurin-giensis. Phylogenetic trees of nucleotide sequences of nprR and 16S rRNA genes were built. Sequences of fourteen new isolates from Papaloapan region were included in those phylo-genetic trees. In order to identify the isolates, a simple and fast methodology considering the Cry protein formation was used. The 16S rRNA phylogenetic tree allows identify eight isolates as Bacillus thuringiensis and the others as Bacillus spp. The nprR phylogenetic tree does not match with the 16S rRNA phylogenetic tree. This confirms that nprR is not a molecular marker for evolution. Most of the new isolates have the same NprR sequence (WTSDIVG). However, the SKPDIVG is the most common NprR sequence in thuringiensis species.展开更多
Objectives: 1) To identify the hydrogeological characteristics and fluoride (F-) concentration in drinking water in the southeast of the state of Morelos, Mexico, and 2) to estimate the association between the prevale...Objectives: 1) To identify the hydrogeological characteristics and fluoride (F-) concentration in drinking water in the southeast of the state of Morelos, Mexico, and 2) to estimate the association between the prevalence and severity of fluorosis, dental caries, and water F-?concentration. Methods: A hydrogeological model was developed to determine the vertical distribution of lithostratigraphic units, rocks’ hydraulic conductivities, and groundwater flow characteristics. A total of 649 schoolchildren from two communities received oral examinations. One community was located in an area with 0.75 mg F-/L in the water supply and the other in an area with 1.6 mg F-/L. Fluorosis was assessed using the Thylstrup & Fejerskov Index (TFI) and the dental caries were assessed with the decayed, missing, and filled teeth (DMFT) index. The region groundwater was extracted from an inter-granular aquifer consisting of volcano clasts of intermediate volcanic chemical composition. Results: Oral examinations showed that 32.35% of the children had severe forms of fluorosis (TFI ≥ 4) in the community with 1.60 mg F-/L and 7.8% in the 0.75 mg F-/L community (p < 0.0001). DMFT = 0.53 (±1.28) and 0.42 (±0.95) in the community with 1.60 mg F-/L and 0.75 mg F-/L, respectively (p = 0.2259). Conclusions: The increasing extraction of underground water was associated with deeper water flows and higher F-?concentration. In the community with high F-concentration, a third of the children showed objectionable levels of fluorosis. Adequate groundwater management actions are required to reduce fluorosis risk.展开更多
Electrochemical techniques were used to oxidize organic pollutants by Fenton process using a mix of H2O2 and ferrous ions at a parallel plate reactor. The first stage was to build a micro scale reactor comprising two ...Electrochemical techniques were used to oxidize organic pollutants by Fenton process using a mix of H2O2 and ferrous ions at a parallel plate reactor. The first stage was to build a micro scale reactor comprising two compartments, cathode and anode, separated by a membrane (Nafion-117). Each compartment has inlets and outlets to allow the flow of fluids (10 Lmin-1). The function of the reactor is to oxidize organic pollutants as well as to produce H2. Hydrogen is electrogenerated in the catholyte by the reduction of protons on a carbon steel cathode in acidic medium (0.05 M H2SO4). At the same time, a mixture of Fe2+/Fe3+ ions is produced in the anolyte (0.05 M Na2SO4, pH ≈ 2) by means of the oxidation of a sacrificial electrode made of stainless steel mesh. Fe2+/Fe3+ ions interact with H2O2 to generate strong oxidants which are responsible for oxidizing the organic matter and removing color. A voltage of 1 V was applied between the electrodes and remained constant, while the current observed was approximately 0.06 A. Under these conditions, the activation rate with different H2O2 concentrations (15, 20, 25, 30, 35, 40, 45 and 50 mM) was evaluated. The maximum activation rate (1.3 mM·min-1) was obtained using 30 mM H2O2. Under these conditions, the oxidation of a synthetic industrial effluent (0.615 mM BB9) was performed and the following results were obtained: 95% of this concentration was removed in 5 minutes and 15 mL of H2 was electrogenerated in 30 minutes.展开更多
At the onset of an infection early defense systems, such as complement, get into action. Specialized leukocytes (white blood cells) of the innate immune system, including monocytes, macrophages, and neutrophils also p...At the onset of an infection early defense systems, such as complement, get into action. Specialized leukocytes (white blood cells) of the innate immune system, including monocytes, macrophages, and neutrophils also participate as a first line of defense against infections. These early responses are rapid but not very specific and are usually not enough to clear completely many infections. The adaptive immune system is also needed to finish the job against many microorganisms. Antibody molecules, produced during the adaptive immune response, are crucial for preventing recurrent infections. Although, IgG antibodies are essential for controlling infections, these molecules do not directly damage the microorganisms they recognize. Today, it is established that leukocytes of the innate immune system are responsible for the protective effects of these antibodies. IgG molecules bind to their cognate antigens and are in turn recognized by specific receptors (Fcγ receptors) on the membrane of leukocytes. Crosslinking these receptors on the surface of leukocytes leads to activation of several effector cell functions. These effector functions are geared toward the destruction of microbial pathogens and the induction of an inflammatory state that is beneficial during infections. However, in autoimmune diseases, antibodies can direct these effector functions against normal tissues and cause severe tissue damage. In recent years, several factors that can modulate the IgG-FcγR interaction have been elucidated. In this review, we describe the main types of Fcγ receptors, and our current view of how antibody variants interact with these receptors to initiate different cell responses. In addition, new findings on the signaling role of individual Fcγ receptors are also discussed.展开更多
A highly acidic spill from one of the most important copper mines in the Americas (Buenavista del Cobre) occurred in Sonora, Mexico in August, 2014. 40,000 m3 of metals-enriched sulphate solution escaped into the Sono...A highly acidic spill from one of the most important copper mines in the Americas (Buenavista del Cobre) occurred in Sonora, Mexico in August, 2014. 40,000 m3 of metals-enriched sulphate solution escaped into the Sonora River representing the worst ecological disaster in Mexican history. The spill affected the economy, water accessibility and the health of residents near the river. Despite the economic importance of mining in this area, no environmental assessment was undertaken. There is no information about the health impact of this event on the local population. The study assesses the health risk among children exposed to arsenic and mercury via groundwater in five communities located in a mining area into the Sonora River Basin, Mexico. Local drinking water from the localities was sampled one year after the spill and it was analyzed for arsenic and mercury by Atomic Absorption Spectrometry coupled with Hydride Generation (AAS/HG). Further, some of the traditional local foods were sampled and analyzed for the same elements. Results indicate that levels of arsenic in drinking water did not exceed the Mexican Norm (25 μg As/L) or the EPA Guideline (10 μg As/L). The concentrations of mercury exceeded the WHO and Mexican Legislation value (1.0 μg Hg/L). The Hazard Quotient (HQ) values for arsenic were >1 in 42% of children exposed and for mercury in 67% of the children. Foods concentrations contained in the ranges of 9.2 to 62.0 μg As/Kg and 0.28 to 42 μg Hg/Kg for arsenic and mercury respectively. These values are below the Codex Alimentarius limits. Children affected by mining activities are at risk of developing chronic diseases associated with low arsenic and mercury exposure via groundwater consumption, without consideration of the contribution from these metals by other important exposures routes.展开更多
In this paper, the generation and control of turbulences in a wind tunnel, for design, analysis and testing of test objects are proposed. Modifications to the wind tunnel are made in order to generate the turbulences ...In this paper, the generation and control of turbulences in a wind tunnel, for design, analysis and testing of test objects are proposed. Modifications to the wind tunnel are made in order to generate the turbulences in the test chamber. Specifically, for the turbulence analysis, the reflective symmetry concept is used in order to group the different turbulences cases generated in the wind tunnel test chamber. The Ansys software is used in order to model and analyze the wind tunnel. Specific platform or module known as Fluent is used for the analysis of the turbulence generated in the wind tunnel. To design proposal of a wind tunnel capable to generate and controlling turbulences is exposed in this paper. For this, the controller design and verification are performed by means of simulations. To obtain the control law structure, the inversion concept is used. The proposed control law is validated via a co-simulation implemented in the Simplorer module, with the aim of combining the power electronics part, controller and engine, with the proposed model wind tunnel.展开更多
The physicochemical properties and catalytic activity of pure and sulfated titanium oxide (TiO2 and ) is described in this work. Titanium hydroxide synthesized by the sol-gel method was impregnated with a 1 N H2SO4 so...The physicochemical properties and catalytic activity of pure and sulfated titanium oxide (TiO2 and ) is described in this work. Titanium hydroxide synthesized by the sol-gel method was impregnated with a 1 N H2SO4 solution, varying amount of sulfate ions () in the range from 10 to 20 wt%. Pure and modified hydroxides were calcined at 500°C for 3 h and then characterized by TGA-DTG, XRD, BET, FT-IR, potentiometric titration with n-butylamine and 2-propanol dehydration. Catalytic activity of materials was tested in the n-hexane isomerization at 350°C. The results showed that TiO2 and mainly developed anatase phase. All have acceptable specific surface area (95-105 m2/g). Potentiometric titration with n-butylamine revealed that showed higher acidity (430-530 mV) than compared to pure TiO2 (﹣15 mV), indicating that this oxide only has weak acidity. The results showed good relationship between acidity determined by potentiometric titration with n-butylamine and the catalytic activity evaluated by 2-propanol dehydration and n-hexane isomerization. Titanium oxide with 20 wt% ofions was the material that demonstrated the highest catalytic activity for both reactions.展开更多
文摘Objective: This work compares the occlusive effect and the penetration enhancement ability of solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC), through in vitro skin. Methods: SLN and NLC were prepared by high shear homogenization and characterized by size, polydispersity index, zeta potential, morphology and physical stability. Occlusive effect was assessed by an in vitro test and by measuring TEWL using pig skin. Skin treated with the lipid carriers was visualized by SEM. A penetration test through skin, followed by tape stripping, was carried out using Nile red as a marker. Results: SLN (200 ± 6 nm) and NLC (192 ± 11 nm) were obtained. An occlusion factor of 36% - 39% was observed for both systems, while a reduction in TEWL of 34.3% ± 14.8% and 26.2% ± 6.5% was seen after treatment with SLN and NLC, respectively. SEM images showed a film formed by the lipid carriers, responsible for the occlusion observed. No differences were found between the occlusive effect produced by SLN and NLC in both tests. NLC allowed the penetration of a greater amount of Nile red than SLN: 4.7 ± 1.3 μg and 1.7 ± 0.4 μg, respectively. Conclusion: Both carriers form a film on the skin, providing an occlusive effect with no differences between these two systems. The penetration of a marker (Nile red) into the stratum corneum was quite higher for NLC than for SLN, suggesting an influence of the composition of these particles on their penetration enhancing ability.
基金the National Council of Science and Technology of Mexico for the postdoc fellowship awarded。
文摘Determining climatic and physiographic variables in Mexico’s major ecoregions that are limiting to biodiversity and species of high conservation concern is essential for their conservation.Yet,at the national level to date,few studies have been performed with large data sets and crossconfirmation using multiple statistical analyses.Here,we used 25 endemic,rare and endangered species from 3610 sampling points throughout Mexico and 25 environmental attributes,including average precipitation for different seasons of the year,annual dryness index,slope of the terrain;and maximum,minimum and average temperatures to test our hypothesis that these species could be assessed with the same weight among all variables,showing similar indices of importance.Our results using principal component analysis,covariation analysis by permutations,and random forest regression showed that summer precipitation,length of the frost-free period,spring precipitation,winter precipitation and growing season precipitation all strongly influence the abundance of tropical species.In contrast,annual precipitation and the balance at different seasons(summer and growing season)were the most relevant variables on the temperate region species.For dry areas,the minimum temperature of the coldest month and the maximum temperature of the warmest month were the most significant variables.Using these different associations in different climatic regions could support a more precise management and conservation plan for the preservation of plant species diversity in forests under different global warming scenarios.
文摘The present study was conducted to evaluate the impact of bimetallic nanoparticles(NPs)of copper(Cu)and zinc(Zn)from Crotalaria longirostrata on the insect mortality and cell viability of Phenacoccus solenopsis.The biosynthesis of bimetallic nanoparticles(Cu/Zn-NPs)from C.longirostrata was confirmed by the presence of a single peak around 378 nm.The hydrodynamic diameter of the Cu/Zn nanoparticles varied from 59 to 119 nm and their zeta potential was found to be−30.90 mV.The EDX analysis showed a strong signal for Cu and Zn(8 and 8.6 keV,respectively).The Cu/Zn-NPs showed an effective insecticide activity against P.solenopsis with 63%of insect mortality after 96 h treatment.However,further studies about nanotoxicity of Cu/Zn-NPs from C.longirostra are needed to reveal the exact mechanism of nanoparticles toxicity in insects.
基金supported by CONACYT-Frontera-1740,CONACy T-CB-288101,CONACy T-299703,and DGAPAPAPIIT-IN101419 projectssupport from the CONACYT Ph.D.-scholarship(CVU 606030)+2 种基金the program Doctorado en Ciencia e Ingeniería de Materials at the Universidad Nacional Autónoma de Méxicothe support from the program Maestría y Doctorado en Ciencias Médicas,Odontológicas y de la Salud at the Universidad Nacional Autónoma de México and the Ph.D.scholarship from CONACy T(CVU 856985)the support from the program Posgrado de Doctorado en Ciencias en Biomedicina y Biotecnología Molecular,Escuela Nacional de Ciencias Biológicas at the Instituto Politécnico Nacional and the Ph.D.scholarship from CONACy T(CVU 739515)
文摘Biodegradable magnesium alloys are promising candidates for temporary fracture fixation devices in orthopedics;nevertheless,its fast degradation rate at the initial stage after implantation remains as one of the main challenges to be resolved.ZrO_(2)-based coatings to reduce the degradation rate of the Mg-implants are an attractive solution since they show high biocompatibility and stability.In this work,the degradation,cytotoxicity,and antibacterial performance of ZrO_(2)thin films deposited by magnetron sputtering on a Mg-Zn-Ca alloy was evaluated.Short-term degradation of ZrO_(2)-coated and uncoated samples was assessed considering electrochemical techniques and H_(2)evolution(gas chromatography).Additionally,long term degradation was assessed by mass-loss measurements.The results showed that a 380 nm ZrO_(2)coating reduces the degradation rate and H_(2)evolution of the alloy during the initial 3 days after immersion but allows the degradation of the bare alloy for the long-term.The ZrO_(2)coating does not compromise the biocompatibility of the alloy and permits better cell adhesion and proliferation of mesenchymal stem cells directly on its surface,in comparison to the bare alloy.Finally,the ZrO_(2)coating prevents the adhesion and biofilm formation of S.aureus.
文摘The essential oils obtained by hydrodistillation from leaves and flowers of Montanoa speciosa collected in southeastern Mexico (Yucatan) were analyzed by GC-MS. A total of 71 and 79 components, representing 98.44% and 97.69% of the leaf and flower oils, respectively, were characterized. The main constituents found were β-caryophyllene (20.73%, 17.95%), δ-cadinene (9.88%, 9.28%), caryophyllene oxide (9.48%, 8.68%), and germacrene D (6.94%, 5.85%). The essential oils were screened for their antioxidant potentials by DPPH assay. The leaves oil exhibited higher DPPH scavenging capability (72.85 ± 0.28 mmol TE/g essential oil and 147.83 ± 0.41 mg/mL Vit C/g essential oil) than the floral oil (68.43 ± 0.10 mmol TE/g essential oil and 131.59 ± 0.87 mg/mL Vit C/g essential oil).
文摘Recently, studies were initiated to investigate the metagenome, which represents the genomes of cultured and uncultured microbes, as a rich source for isolation of many novel genes. The meta-genomic approach originated from the molecular analysis of microbial communities, which revealed that the majority of microorganisms in nature were not cultivable by standard culturing techniques. Therefore, most microorganisms in nature have not been characterized. Although numerous methods have been reported for direct DNA isolation and purification from microorganisms in soil, the sample preparation procedures and experimental conditions used in different studies vary widely. Soils are therefore one of the most challenging environmental matrices from which to obtain microbial DNA that will support PCR. The Papaloapan River is the second largest river basin in México. For the climatic conditions of this region, there is great diversity in plants, animals and microorganisms. In the Papaloapan region different fruits are grown, however, the main crops are sugarcane and pineapple. In this work the extraction of DNA from soils of sugarcane cultivation was performed. We used PCR tests to assess the quality of DNA extracted from soil by amplifying the 16S rDNA gene. Changes in both protocols were performed;satisfactory results were obtained as to the quality of DNA and gene amplification. These results will allow continuing the metagenomic studies, such as sequencing, library construction and identification of enzymes cellulase and amylase activity. It is the first time these studies were performed in the Papaloapan region.
文摘The cellular strategy leading to formation of neuronal circuits in the rodent barrel cortex is still a matter of controversy. Both selective and constructive mechanisms have been proposed. The selective mechanism involves an overproduction of neuronal processes and synapses followed by activity dependent pruning. Conversely, a constructive mechanism would increase the number of axons, dendrites, and synapses during development to match functionality. In order to discern the contributions of these two mechanisms in establishing a neuronal circuit in the somatosensory cortex, morphometric analysis of dendritic and axonal arbor growth was performed. Also, the number of synapses was followed by electron microscopy during the first month of life. We observed that axonal and dendritic arbors retracted distal branches, and elongated proximal branches, resulting in increased arbor complexity. This neuronal remodeling was accompanied by the steady increase in the number of synapses within barrel hollows. Similarly, the content of molecular markers for dendrites, axons and synapses also increased during this period. Finally, cytochrome oxidase activity rose with age in barrels indicating that the arbors became more complex while synapse density and metabolic demands increased. Our results support the simultaneous use of both selective and constructive mechanisms in establishing the barrel cortex circuitry.
文摘Quorum sensing is a chemical communication process that bacteria use to regulate collective behaviors. In Gram-positive bacteria, oligopeptides (called autoinducers) are the signaling molecules to elicit quorum sensing. In Bacillus thuringiensis, NprR is a transcriptional regulator whose activity depends on the NprX signalling peptide. Bacillus thuringiensis is closely related to Bacillus cereus and Bacillus anthracis. The principal difference between them is that Bacillus thuringiensis is the only one that produced Cry protein. The aim of this study is to explore the relation of nprR and 16S rRNA genes in Bacillus thurin-giensis. Phylogenetic trees of nucleotide sequences of nprR and 16S rRNA genes were built. Sequences of fourteen new isolates from Papaloapan region were included in those phylo-genetic trees. In order to identify the isolates, a simple and fast methodology considering the Cry protein formation was used. The 16S rRNA phylogenetic tree allows identify eight isolates as Bacillus thuringiensis and the others as Bacillus spp. The nprR phylogenetic tree does not match with the 16S rRNA phylogenetic tree. This confirms that nprR is not a molecular marker for evolution. Most of the new isolates have the same NprR sequence (WTSDIVG). However, the SKPDIVG is the most common NprR sequence in thuringiensis species.
文摘Objectives: 1) To identify the hydrogeological characteristics and fluoride (F-) concentration in drinking water in the southeast of the state of Morelos, Mexico, and 2) to estimate the association between the prevalence and severity of fluorosis, dental caries, and water F-?concentration. Methods: A hydrogeological model was developed to determine the vertical distribution of lithostratigraphic units, rocks’ hydraulic conductivities, and groundwater flow characteristics. A total of 649 schoolchildren from two communities received oral examinations. One community was located in an area with 0.75 mg F-/L in the water supply and the other in an area with 1.6 mg F-/L. Fluorosis was assessed using the Thylstrup & Fejerskov Index (TFI) and the dental caries were assessed with the decayed, missing, and filled teeth (DMFT) index. The region groundwater was extracted from an inter-granular aquifer consisting of volcano clasts of intermediate volcanic chemical composition. Results: Oral examinations showed that 32.35% of the children had severe forms of fluorosis (TFI ≥ 4) in the community with 1.60 mg F-/L and 7.8% in the 0.75 mg F-/L community (p < 0.0001). DMFT = 0.53 (±1.28) and 0.42 (±0.95) in the community with 1.60 mg F-/L and 0.75 mg F-/L, respectively (p = 0.2259). Conclusions: The increasing extraction of underground water was associated with deeper water flows and higher F-?concentration. In the community with high F-concentration, a third of the children showed objectionable levels of fluorosis. Adequate groundwater management actions are required to reduce fluorosis risk.
文摘Electrochemical techniques were used to oxidize organic pollutants by Fenton process using a mix of H2O2 and ferrous ions at a parallel plate reactor. The first stage was to build a micro scale reactor comprising two compartments, cathode and anode, separated by a membrane (Nafion-117). Each compartment has inlets and outlets to allow the flow of fluids (10 Lmin-1). The function of the reactor is to oxidize organic pollutants as well as to produce H2. Hydrogen is electrogenerated in the catholyte by the reduction of protons on a carbon steel cathode in acidic medium (0.05 M H2SO4). At the same time, a mixture of Fe2+/Fe3+ ions is produced in the anolyte (0.05 M Na2SO4, pH ≈ 2) by means of the oxidation of a sacrificial electrode made of stainless steel mesh. Fe2+/Fe3+ ions interact with H2O2 to generate strong oxidants which are responsible for oxidizing the organic matter and removing color. A voltage of 1 V was applied between the electrodes and remained constant, while the current observed was approximately 0.06 A. Under these conditions, the activation rate with different H2O2 concentrations (15, 20, 25, 30, 35, 40, 45 and 50 mM) was evaluated. The maximum activation rate (1.3 mM·min-1) was obtained using 30 mM H2O2. Under these conditions, the oxidation of a synthetic industrial effluent (0.615 mM BB9) was performed and the following results were obtained: 95% of this concentration was removed in 5 minutes and 15 mL of H2 was electrogenerated in 30 minutes.
文摘At the onset of an infection early defense systems, such as complement, get into action. Specialized leukocytes (white blood cells) of the innate immune system, including monocytes, macrophages, and neutrophils also participate as a first line of defense against infections. These early responses are rapid but not very specific and are usually not enough to clear completely many infections. The adaptive immune system is also needed to finish the job against many microorganisms. Antibody molecules, produced during the adaptive immune response, are crucial for preventing recurrent infections. Although, IgG antibodies are essential for controlling infections, these molecules do not directly damage the microorganisms they recognize. Today, it is established that leukocytes of the innate immune system are responsible for the protective effects of these antibodies. IgG molecules bind to their cognate antigens and are in turn recognized by specific receptors (Fcγ receptors) on the membrane of leukocytes. Crosslinking these receptors on the surface of leukocytes leads to activation of several effector cell functions. These effector functions are geared toward the destruction of microbial pathogens and the induction of an inflammatory state that is beneficial during infections. However, in autoimmune diseases, antibodies can direct these effector functions against normal tissues and cause severe tissue damage. In recent years, several factors that can modulate the IgG-FcγR interaction have been elucidated. In this review, we describe the main types of Fcγ receptors, and our current view of how antibody variants interact with these receptors to initiate different cell responses. In addition, new findings on the signaling role of individual Fcγ receptors are also discussed.
文摘A highly acidic spill from one of the most important copper mines in the Americas (Buenavista del Cobre) occurred in Sonora, Mexico in August, 2014. 40,000 m3 of metals-enriched sulphate solution escaped into the Sonora River representing the worst ecological disaster in Mexican history. The spill affected the economy, water accessibility and the health of residents near the river. Despite the economic importance of mining in this area, no environmental assessment was undertaken. There is no information about the health impact of this event on the local population. The study assesses the health risk among children exposed to arsenic and mercury via groundwater in five communities located in a mining area into the Sonora River Basin, Mexico. Local drinking water from the localities was sampled one year after the spill and it was analyzed for arsenic and mercury by Atomic Absorption Spectrometry coupled with Hydride Generation (AAS/HG). Further, some of the traditional local foods were sampled and analyzed for the same elements. Results indicate that levels of arsenic in drinking water did not exceed the Mexican Norm (25 μg As/L) or the EPA Guideline (10 μg As/L). The concentrations of mercury exceeded the WHO and Mexican Legislation value (1.0 μg Hg/L). The Hazard Quotient (HQ) values for arsenic were >1 in 42% of children exposed and for mercury in 67% of the children. Foods concentrations contained in the ranges of 9.2 to 62.0 μg As/Kg and 0.28 to 42 μg Hg/Kg for arsenic and mercury respectively. These values are below the Codex Alimentarius limits. Children affected by mining activities are at risk of developing chronic diseases associated with low arsenic and mercury exposure via groundwater consumption, without consideration of the contribution from these metals by other important exposures routes.
文摘In this paper, the generation and control of turbulences in a wind tunnel, for design, analysis and testing of test objects are proposed. Modifications to the wind tunnel are made in order to generate the turbulences in the test chamber. Specifically, for the turbulence analysis, the reflective symmetry concept is used in order to group the different turbulences cases generated in the wind tunnel test chamber. The Ansys software is used in order to model and analyze the wind tunnel. Specific platform or module known as Fluent is used for the analysis of the turbulence generated in the wind tunnel. To design proposal of a wind tunnel capable to generate and controlling turbulences is exposed in this paper. For this, the controller design and verification are performed by means of simulations. To obtain the control law structure, the inversion concept is used. The proposed control law is validated via a co-simulation implemented in the Simplorer module, with the aim of combining the power electronics part, controller and engine, with the proposed model wind tunnel.
基金This work was supported by the National Council for Science and Technology CONACYT(Mihalcea PhD scholarship 473734 and Dr.Chávez postdoctoral fellow 000614)The authors would like to thank the CIC of the UMSNH and the National Laboratory SEDEAM-CONACYT for the financial support and the facilities provided for the development of this study.We would also like to thank the Laboratory“LUMIR”Geosciences of the UNAM,Juriquilla,for the 3D image acquisition and processing.
基金CONACy T through the project CB-167111the Scientific Research Department of the UMSNH and the Guadalajara University for the financial support and the facilities to develop this study
文摘The physicochemical properties and catalytic activity of pure and sulfated titanium oxide (TiO2 and ) is described in this work. Titanium hydroxide synthesized by the sol-gel method was impregnated with a 1 N H2SO4 solution, varying amount of sulfate ions () in the range from 10 to 20 wt%. Pure and modified hydroxides were calcined at 500°C for 3 h and then characterized by TGA-DTG, XRD, BET, FT-IR, potentiometric titration with n-butylamine and 2-propanol dehydration. Catalytic activity of materials was tested in the n-hexane isomerization at 350°C. The results showed that TiO2 and mainly developed anatase phase. All have acceptable specific surface area (95-105 m2/g). Potentiometric titration with n-butylamine revealed that showed higher acidity (430-530 mV) than compared to pure TiO2 (﹣15 mV), indicating that this oxide only has weak acidity. The results showed good relationship between acidity determined by potentiometric titration with n-butylamine and the catalytic activity evaluated by 2-propanol dehydration and n-hexane isomerization. Titanium oxide with 20 wt% ofions was the material that demonstrated the highest catalytic activity for both reactions.