Temperature is a key factor that shapes the distribution of organisms.Having knowledge about how species respond to temperature is relevant to devise strategies for addressing the impacts of climate change.Aquatic ins...Temperature is a key factor that shapes the distribution of organisms.Having knowledge about how species respond to temperature is relevant to devise strategies for addressing the impacts of climate change.Aquatic insects are particularly vulnerable to climate change,yet there is still much to learn about their ecology and distribution.In the Yungas ecoregion of Northwestern Argentina,cold-and warm-adapted species of the orders Ephemeroptera,Plecoptera,and Trichoptera(EPT)are segregated by elevation.We modeled the ecological niche of South American EPT species in this region using available data and projected their potential distribution in geographic space.Species were grouped based on their ecogeographic similarity,and we analyzed their replacement pattern along elevation gradients,focusing on the ecotone where opposing thermal preferences converge.Along this interface,we identified critical points where the combined incidence of cold and warm assemblages maximizes,indicating a significant transition zone.We found that the Montane Cloud Forest holds the interface,with a particularly greater suitability at its lower boundary.The main axis of the interface runs in a N-S direction and falls between 14°C-16°C mean annual isotherms.The probability of a particular location within a basin being classified as part of the interface increases as Kira’s warmth index approaches a score around 150.Understanding the interface is critical for defining the thermal limits of species distribution and designing biomonitoring programs.Changes in the location of thermal constants related to mountainous ecotones may cause vertical displacement of aquatic insects and vegetation communities.We have recognized significant temperature thresholds that serve as indicators of suitability for the interface.As global warming is anticipated to shift these indicators,we suggest using them to monitor the imprints of climate change on mountain ecosystems.展开更多
In recent years,there has been an increasing interest in finding sustainable strategies for the efficient removal of contaminants from soils.The objective of this review is to examine the biochemical principles of spe...In recent years,there has been an increasing interest in finding sustainable strategies for the efficient removal of contaminants from soils.The objective of this review is to examine the biochemical principles of specific genetic modifications in plants,their applications in the field for specific contaminants as phytotechnologies,and their international regulation.In addition,the review presents some biological aspects of rhizosphere-related phenomena,the interactions of organic and inorganic pollutants with plants,and the performance of the phytotechnologies across the continents.During the last few decades,at least eight genera of genetically modified plants(GMPs)have been tested and used for soil remediation with outstanding results.Arabidopsis,Nicotiana,and Oryza are the plant genera most widely studied.Specific plant genes such as metal transporters,chelators,metallothioneins,phytochelatins,and oxygenases have been transferred to plants to improve the elimination of contaminants in soil.We discuss some important aspects of gene manipulation and its application for removal of diverse contaminants.A key challenge faced by phytotechnologies is the final disposal of the generated biomass,from a safety aspect.We argue that the commercial success of phytotechnologies depends on the generation of valuable biomass on contaminated land and its use for bioenergy generation.The use of such technologies would promote a broader understanding of the importance of plants,especially GMPs,in the environment and their contribution to environmental sustainability.展开更多
This paper presents the erosion results of the AISI H13 steel impinged by resin-bonded silica sand, using a testing rig that closely simulates the real blowing conditions during industrial core-making. Steel specimens...This paper presents the erosion results of the AISI H13 steel impinged by resin-bonded silica sand, using a testing rig that closely simulates the real blowing conditions during industrial core-making. Steel specimens were heat treated to obtain hardness of 294, 445 and 595 HV200 (29, 45 and 55 HRC). Erosion tests were carried out at impingement angles from 20° to 90° and air drag pressures of 1.38, 2.07 and 2.76 bar (20, 30 and 40 psi). The main results are summarized as follows:(i) The harder material, the lower erosion;(ii) the maximum erosion rate is at 30°;(iii) Little difference in erosion rate at impact angle of 60° and 90° for a constant pressure tested regardless of the hardness level;(iv) As the pressure increases, so does the erosion rate, being more sensitive for low impact angles. Finally, a differential form of the general erosion equation is applied on a practical core-making case to evaluate the erosion rate of the H13 steel at 30° and 90° impingement angles.展开更多
Fe_(3)O_(4)magnetic xerogel composites were prepared by polycondensation of resorcinol(R)-formaldehyde reaction via a sol-gel process in an aqueous solution through varying the molar ratio of Fe_(3)O_(4)nanoparticles(...Fe_(3)O_(4)magnetic xerogel composites were prepared by polycondensation of resorcinol(R)-formaldehyde reaction via a sol-gel process in an aqueous solution through varying the molar ratio of Fe_(3)O_(4)nanoparticles(MNPs),catalyst(C),and water(W)content.MNPs were obtained by co-precipitation(MC),oxidation of iron salts(MO),or solvothermal synthesis(MS).Both MNPs and magnetic xerogels were examined regarding the performance of arsenic and fluoride removal in a batch system.The MC-based MNPs had higher adsorption capacities for both fluoride(202.9 mg/g)and arsenic(3.2 mg/g)than other MNPs in optimum conditions.The X-ray diffraction,Fourier transform infrared spectroscopy,and energy-dispersive X-ray spectroscopy confirmed that Fe was composed into the polymeric matrix of magnetic xerogels that contained 0.59%-4.42%of Fe with a molar ratio of MNPs(M)to R between 0.01 and 0.10.With low R/C and optimum M/R ratios,an increase in the surface area of magnetic xerogels affected the fluoride and arsenic adsorption capacities.The magnetic xerogel composites with the MC-based MNPs prepared at a fixed R/C ratio(100)and at different R/W(0.05-0.06)and M/R(0.07-0.10)ratios had a high arsenic removal efficiency of 100%at an As(V)concentration of 0.1 mg/L and pH of 3.0.The maximum adsorption capacities of magnetic xerogels were approximately five times higher than those of the xerogels without MNP composites.Therefore,Fe_(3)O_(4)nanoparticles enhanced the adsorption of arsenate and fluoride.The variations of alkaline catalyst and water content significantly affected the resulting properties of textural and surface chemistry of magnetic xerogel composites.展开更多
In saline water flotation, the salinity can cause a distinguishable slime coating of clay minerals on chalcopyrite particles through its effect on their electrical double layers in aqueous solutions. In this work, kao...In saline water flotation, the salinity can cause a distinguishable slime coating of clay minerals on chalcopyrite particles through its effect on their electrical double layers in aqueous solutions. In this work, kaolinite was used as a representative clay mineral for studying slime coating during chalcopyrite flotation. The flotation of chalcopyrite in the presence and absence of kaolinite in tap water, seawater, and gypsum-saturated water and the stability of chalcopyrite and kaolinite particles in slurries are presented. Zeta-potential distributions and scanning electron microscopy images were used to characterize and explain the different slime coating degrees and the different flotation performances. Kaolinite particles induced slime coating on chalcopyrite surfaces and reduced chalcopyrite floatability to the greatest extent when the p H value was in the alkaline range. At 0.24 wt% of kaolinite, the chalcopyrite floatability was depressed by more than 10% at alkaline p H levels in tap water. Salinity in seawater and gypsum-saturated water compressed the electrical double layers and resulted in extensive slime coating.展开更多
A microstructural analysis was performed to determine the presence of oxygen in a wire rod section of AISI 1008 steel with a surface mechanical failure produced during wire drawing.The failure zone was analyzed by com...A microstructural analysis was performed to determine the presence of oxygen in a wire rod section of AISI 1008 steel with a surface mechanical failure produced during wire drawing.The failure zone was analyzed by comparison using three different attack reagents:alkaline sodium chromate(ASC),ASC with hydrogen peroxide and amyl alcohol,and a solution of nitric acid in ethyl alcohol.The reagents were applied in samples in the failure zone,showing different types of zones in regions with internal and superficial defects such as carbides,pores,cracks,deformation,and detachment zones,indicating the possible presence of oxygen.The areas identified were observed by means of an optical microscope and were correlated with the content of elements that were present in the region using a scanning electron microscope and a scattered X-ray energy spectrometer,which determined that the areas identified by chromate sodium correspond to regions with a high concentration of oxygen and slag-forming elements such as silicon,aluminum,and iron;this is associated with the presence of oxygen in the oxide form.It was also observed that the ASC and the modified ASC solution with hydrogen peroxide and amyl alcohol could identify areas with a high presence of oxides,while the nitric acid solution only identified the steel microstructure.The modified ASC solution is an alternative to identify the presence of chemical variants of oxygen because the conventional formulation is unstable and has a too short shelf life,and therefore,its application must be carried out at the time of preparation.展开更多
A numerical simulation was performed to study the flow pattern,mixing time and open-eye slag produced by argon gas injection in an industrial scale steel ladle under non-isothermal conditions.The liquid steel remains ...A numerical simulation was performed to study the flow pattern,mixing time and open-eye slag produced by argon gas injection in an industrial scale steel ladle under non-isothermal conditions.The liquid steel remains 5min before the injection,and thermal stratification and convective flows were analyzed.Three different sequences in stages employing various argon-gas flow rates were simulated.In the first case,a sequence with the highest flow rates of argon was applied,while in the second and the third sequences,the intermediate and the lowest flow rates of argon gas were used,respectively.For determining the chemistry homogenization,the mixing time was computed and analyzed in all three cases.It was found that the cold steel is located near the walls while the steel with a high temperature is accumulated in the center of the ladle above the argon-gas tuyere.The higher and lower flows promote a faster chemistry homogenization owing to the secondary recirculations that are developed closer to the walls.The results from steel temperature drop show a good concordance with plant trial measurements.展开更多
Assisted migration has been proposed as a strategy for adaptive management of forest species in response to expected effects of climate change,but it is controversial for several reasons.Tropical dry forests are among...Assisted migration has been proposed as a strategy for adaptive management of forest species in response to expected effects of climate change,but it is controversial for several reasons.Tropical dry forests are among the most threatened ecosystems in the world.In Mexico,historically,land-use change and deforestation have been decreasing forest cover,and climate change is shifting the potential distribution of different forest types,exacerbating the risk of local extinctions.Assisted altitudinal migration could be a feasible strategy for reducing local extinctions in response to climate change and lack of landscape connectivity.Our objective was to evaluate survival and growth of Albizia plurijuga and Ceiba aesculifolia,two tropical deciduous forests species in Mexico.We transplanted 4-month-old seedlings to experimental raised beds at three altitudes(2100,2400 and 2700 m a.s.l.),exceeding their upper regional limit of distribution(2000 m a.s.l.).We also tested seed germination at each altitude.We monitored the experiment for 10 months.For both species,as altitude increased and cold weather was more prevalent,plant performance declined.Within species,differences in individual growth were significant among altitudes.Overall survival was 18.5%for A.plurijuga and 24.5%for C.aesculifolia.Both species had higher survival and better growth at lower altitude,and no seedling emergence at any altitude.We conclude that assisted migration can be implemented for each species by an upward attitudinal shift within,and not exceeding,400 m beyond their present upper altitudinal limit of distribution.Our results indicate that for many species that show altitudinal gradients at regional scales,unless current climate conditions change,the potential to establish outside their range is minimal.展开更多
The high mortality rate of breast cancer is mainly caused by the metastatic ability of cancer cells,resistance to chemotherapy and radiotherapy,and tumor regression capacity.In recent years,it has been shown that the ...The high mortality rate of breast cancer is mainly caused by the metastatic ability of cancer cells,resistance to chemotherapy and radiotherapy,and tumor regression capacity.In recent years,it has been shown that the presence of breast cancer stem cells is closely associated with the migration and metastatic ability of cancer cells,as well as with their resistance to chemotherapy and radiotherapy.The tumor microenvironment is one of the main molecular factors involved in cancer and metastatic processes development,in this sense it is interesting to study the role of platelets,one of the main communicator cells in the human body which are activated by the signals they receive from the microenvironment and can generate more than one response.Platelets can ingest and release RNA,proteins,cytokines and growth factors.After the platelets interact with the tumor microenvironment,they are called"tumor-educated platelets."Tumor-educated platelets transport material from the tumor microenvironment to sites adjacent to the tumor,thus helping to create microenvironments conducive for the development of primary and metastatic tumors.It has been observed that the clone capable of carrying out the metastatic process is a cancer cell with stem cell characteristics.Cancer stem cells go through a series of processes,including epithelial-mesenchymal transition,intravasation into blood vessels,movement through blood vessels,extravasation at the site of the establishment of a metastatic focus,and site colonization.Tumor-educated platelets support all these processes.展开更多
The powders of the AA 7075-ZRO2 were mixed by mechanical milling, but it was found that the system presents a few disadvantages when processed by conventional sintering and hot extrusion, since intermetallic phases be...The powders of the AA 7075-ZRO2 were mixed by mechanical milling, but it was found that the system presents a few disadvantages when processed by conventional sintering and hot extrusion, since intermetallic phases between ZrO2 particles and alloying elements were formed. Equal channel angular pressing （ECAP） processing was proposed as an alternative method to consolidate the composite where there is no intermetallic formation. The analysis of the ECAP process showed that the intermediate temperature （220℃） produced a higher consolidation level than conventional sintering and hot extrusion （400 and 500℃, respectively）. This fact was supported by relative density analysis. In the case of the sintered and hot-extruded sample, the relative density exhibited a value of 0.95, while ECAP sample showed a value of 0.98. Hardness values show that microstructural refinement obtained during mechanical milling was preserved during ECAP processing even when it was carded out at 220℃.展开更多
AIM To determine a potential relationship between serum undercarboxylated(uc OC) concentration and cardiovascular risk factors in type 2 diabetes(T2D) patients and healthy subjects(HS).METHODS A cross-sectional study ...AIM To determine a potential relationship between serum undercarboxylated(uc OC) concentration and cardiovascular risk factors in type 2 diabetes(T2D) patients and healthy subjects(HS).METHODS A cross-sectional study was conducted on 140 subjects classified into two groups, 70 with T2D and 70 HS. Medical history and physical examination with anthropometric measurements were obtained from all subjects. Body fat percentage was determined by bioelectrical impendency analysis. Serum uc OC concentration was determined by enzyme immunoassay,while serum levels of insulin and hsC RP were obtained using high sensitivity enzyme-linked immunosorbent assay. Insulin resistance was determined using the homeostasis model assessment-IR. Lipid profile [triglycerides,total cholesterol(TC), high-density lipoproteins(HDL-c),low density lipoproteins(LDL-c), very low-density lipoproteins] was determined by spectrophotometry and standard formulas when applicable. RESULTS The T2D patient group showed significantly higher values of waist circumference, waist-to-hip ratio, systolic blood pressure(SBP), diastolic blood pressure(DBP),current smoking, and alcohol use when compared to the HS group(P < 0.05). We observed a significantly lower serum ucO C concentration in T2D than in HS(1.5 ± 1.4vs 2.3 ± 1.8, P < 0.05). In the whole study population,ucO C concentration was inversely correlated with body mass index(BMI)(r =-0.236, P < 0.05), fasting plasma glucose(r =-0.283, P < 0.01) and HDL-c(r =-0.255,P < 0.05); and positively correlated with LDL-c/HDL-c ratio(r = 0.306, P < 0.05) and TC/HDL-c ratio(r =0.284, P < 0.05). In the T2D group, serum uc OC concentration was inversely correlated with BMI(r =-0.310, P < 0.05) and body-fat percentage(r =-0.311,P < 0.05), and positively correlated with DBP(r = 0.450,P < 0.01). In HS group a positive correlation between serum levels of uc OC and SBP(r = 0.277, P < 0.05)was observed. CONCLUSION Serum uc OC is a potential marker for cardiovascular risk in Mexicans because it is related to adiposity parameters, blood pressure and lipid profile.展开更多
Background:Among urban stimuli,anthropogenic noise has been identified to be one of the behavioral drivers of species that rely on acoustic signals for communication.Studies have shown both species‑specific and assemb...Background:Among urban stimuli,anthropogenic noise has been identified to be one of the behavioral drivers of species that rely on acoustic signals for communication.Studies have shown both species‑specific and assemblage responses to urban noise,ranging from the modulation of their acoustic frequencies and spatiotemporal adjustments to declines in species richness.In this study,we assessed the citywide relationship between two anthropogenic noise variables(noise levels recorded during bird surveys and daily average noise levels)and vegetation cover with bird species richness.Methods:This study was conducted in the city of Xalapa(Mexico)through a 114 citywide point‑count survey.We recorded bird communities at each sampling site.We measured noise levels using a sound level meter while performing point‑counts.Then,we generated a map of average daily noise of the city using an array of 61 autonomous recording units distributed across the city of Xalapa and calculated daily noise levels for the 114 points.We ran a linear model(LM)to assess potential relationships between both point‑count and daily(24 h)noise values and vegetation cover with bird richness.Results:Results from the LM show:(1)a negative relationship between maximum point‑count noise and avian species richness,(2)no relationship between 24 h noise and bird species richness,and(3)a positive relationship between vegetation cover and bird species richness.Conclusions:Results provide evidence that decreases in urban bird species richness do not necessarily imply the permanent absence of species,suggesting that birds can temporarily fly away from or avoid sites when noisy,become cryptic while noisy events are occurring,or be undetected due to our inability to record them in the field during noisy events.展开更多
In this work we study the quantum system with the symmetric Konwent potential and show how to find its exact solutions. We find that the solutions are given by the confluent Heun function. The eigenvalues have to be c...In this work we study the quantum system with the symmetric Konwent potential and show how to find its exact solutions. We find that the solutions are given by the confluent Heun function. The eigenvalues have to be calculated numerically because series expansion method does not work due to the variable z ≥ 1. The properties of the wave functions depending on the potential parameter A are illustrated for given potential parameters V_0 and a. The wave functions are shrunk towards the origin with the increasing |A|. In particular, the amplitude of wave function of the second excited state moves towards the origin when the positive parameter A decreases. We notice that the energy levels ε_i increase with the increasing potential parameter |A| ≥ 1, but the variation of the energy levels becomes complicated for |A| ∈(0, 1), which possesses a double well. It is seen that the energy levels ε_i increase with |A| for the parameter interval A ∈(-1, 0), while they decrease with |A| for the parameter interval A ∈(0, 1).展开更多
Background:Studies on the relationship between biodiversity and ecosystem productivity have suggested that species richness and functional diversity are the main drivers of ecosystem processes.Several patterns on this...Background:Studies on the relationship between biodiversity and ecosystem productivity have suggested that species richness and functional diversity are the main drivers of ecosystem processes.Several patterns on this relationship have been found,including positive,unimodal,negative,and neutral trends,keeping the issue controversial.In this study,taxonomic diversity and functional diversity as drivers of above-ground biomass(AGB)were compared,and the mechanisms that influence biomass production were investigated by testing the complementarity and the mass-ratio hypotheses.Methods:Using data from 414 permanent sample plots,covering 23%of temperate forest in the Sierra Madre Oriental(México),we estimated the above-gound biomass(AGB),taxonomic and functional diversity indices,as well as community weighted mean values(CWM)for three functional traits(maximum height,leaf size and wood density)for trees≥7.5 cm DBH,in managed and unmanaged stands.To compare taxonomic diversity differences between managed and unmanaged stands we carried out a rarefaction analysis.Furthermore,we evaluated the relationship between AGB and taxonomic and functional diversity metrics,as well as CWM traits throught spatial autoregressive models.Results:We found a hump-shaped relationship between AGB and species richness in managed and unmanaged forests.CMW of maximum height was the most important predictor of AGB in both stands,which suggested that the mechanism underlaying the AGB-diversity relationship is the dominance of some highly productive species,supporting the mass-ratio hypothesis.Above-ground biomass was significantly correlated with three of the five functional diversity metrics,CWM maximum height and species richness.Our results show the importance of taking into account spatial autocorrelation in the construction of predictive models to avoid spurious patterns in the AGBdiversity relationship.Conclusion:Species richness,maximum height,functional richness,functional dispersion and RaoQ indices relate with above-ground biomass production in temperate mixed-species and uneven-aged forests of northern Mexico.These forests show a hump-shaped AGB-species richness relationship.Functional diversity explains better AGB production than classical taxonomic diversity.Community weighted mean traits provide key information to explain stand biomass in these forests,where maximum tree height seems to be a more suitable trait for understanding the biomass accumulation process in these ecosystems.Although the impact of forest management on biodiversity is still debated,it has not changed the AGB-diversity relationships in the forests of the Sierra Madre Occidental,Mexico.展开更多
Using a single-mode approximation, we carry out the entanglement measures, e.g., the negativity and von Neumann entropy when a tetrapartite generalized GHZ state is treated in a noninertial frame, but only uniform acc...Using a single-mode approximation, we carry out the entanglement measures, e.g., the negativity and von Neumann entropy when a tetrapartite generalized GHZ state is treated in a noninertial frame, but only uniform acceleration is considered for simplicity. In terms of explicit negativity calculated, we notice that the difference between the algebraic average π_(4) and geometric average Π_(4) is very small with the increasing accelerated observers and they are totally equal when all four qubits are accelerated simultaneously. The entanglement properties are discussed from one accelerated observer to all four accelerated observers. It is shown that the entanglement still exists even if the acceleration parameter r goes to infinity. It is interesting to discover that all 1-1 tangles are equal to zero, but 1-3 and 2-2 tangles always decrease when the acceleration parameter γ increases. We also study the von Neumann entropy and find that it increases with the number of the accelerated observers. In addition, we find that the von Neumann entropy S_(ABCDI), S_(ABCIDI), S_(ABICIDI) and S_(AIBICIDI) always decrease with the controllable angle θ, while the entropies S_(3-3 non), S_(3-2 non), S_(3-1 non) and S_(3-0 non) first increase with the angle θ and then decrease with it.展开更多
Using the single-mode approximation,we study entanglement measures including two independent quantities;i.e.,negativity and von Neumann entropy for a tripartite generalized Greenberger-Horne-Zeilinger(GHZ)state in non...Using the single-mode approximation,we study entanglement measures including two independent quantities;i.e.,negativity and von Neumann entropy for a tripartite generalized Greenberger-Horne-Zeilinger(GHZ)state in noninertial frames.Based on the calculated negativity,we study the whole entanglement measures named as the algebraic average π3-tangle and geometric average Π3-tangle.We find that the difference between them is very small or disappears with the increase of the number of accelerated qubits.The entanglement properties are discussed from one accelerated observer and others remaining stationary to all three accelerated observers.The results show that there will always exist entanglement,even if acceleration r arrives to infinity.The degree of entanglement for all 1-1 tangles are alwa.ys equal to zero,but 1-2 tangles always decrease with the acceleration parameter r.We notice that the von Neumann entropy increases with the number of the accelerated observers and SκΙζΙ(κ,ζ∈(A,B,C)) first increases and then decreases with the acceleration parameter r.This implies that the subsystem ρκΙζΙ is first more disorder and then the disorder will be reduced as the acceleration parameter r increases.Moreover,it is found that the von Neumann entropies SABCI,SABICI and SAIBICI always decrease with the controllable angle θ,while the entropies of the bipartite subsystems S2-2non(two accelerated qubits),S2-1non(one accelerated qubit) and S2-0non(without accelerated qubit) first increase with the angle θ and then decrease with it.展开更多
Efforts to improve crop yields with efficient use of fertilizers are needed to guarantee global food security.Enhanced slow-release fertilizer systems(SRFs)encapsulated in biodegradable matrices are being developed to...Efforts to improve crop yields with efficient use of fertilizers are needed to guarantee global food security.Enhanced slow-release fertilizer systems(SRFs)encapsulated in biodegradable matrices are being developed to address this global concern.From a wide range of strategies for SRFs development,we explored a natureinspired solution based on the plant cuticle model and its function as a membrane for water and nutrient transport control.Here,Candelilla wax,extracted from Candelilla wild plants(Euphorbia antisyphilitica),is studied as a renewable slow-release matrix for fertilizers encapsulated by a modified spray chilling process.From this process,microencapsulates containing 40 wt%of phosphorus fertilizer are obtained with distinctive sizes and chemical characteristics,presenting a slow-release behavior.Considering the abovementioned features,novel insights into fertilizer release mechanisms based on plant cuticle models are discussed.展开更多
We first study the Shannon information entropies of constant total length multiple quantum well systems and then explore the effects of the number of wells and confining potential depth on position and momentum inform...We first study the Shannon information entropies of constant total length multiple quantum well systems and then explore the effects of the number of wells and confining potential depth on position and momentum information entropy density as well as the corresponding Shannon entropy.We find that for small full width at half maximum（FWHM） of the position entropy density,the FWHM of the momentum entropy density is large and vice versa.By increasing the confined potential depth,the FWHM of the position entropy density decreases while the FWHM of the momentum entropy density increases.By increasing the potential depth,the frequency of the position entropy density oscillation within the quantum barrier decreases while that of the position entropy density oscillation within the quantum well increases.By increasing the number of wells,the frequency of the position entropy density oscillation decreases inside the barriers while it increases inside the quantum well.As an example,we might localize the ground state as well as the position entropy densities of the1 st,2 nd,and 6 th excited states for a four-well quantum system.Also,we verify the Bialynicki–Birula–Mycieslki（BBM）inequality.展开更多
Based on a Hamfltonian identity, we study one-dimensional generalized hypervirial theorem, Blanchardlike （non-diagonal case） and Kramers＇ （diagonal case） recurrence relations for arbitrary x^k which is independen...Based on a Hamfltonian identity, we study one-dimensional generalized hypervirial theorem, Blanchardlike （non-diagonal case） and Kramers＇ （diagonal case） recurrence relations for arbitrary x^k which is independent of the central potential V（x）. Some significant results in diagonal case are obtained for special k in xk （k ≥2）. In particular, we find the orthogonal relation 〈n1｜n2〉 = δh1,n2 （k = 0）, 〈n1[V＇（x）｜n2〉 = （En1-En2）^2〈n1｜x｜n2〉 （k = 1）, En = （n｜V＇（x）x/2｜n〉 ＋ （n｜V（x）｜n〉 （k = 2） and -4En（n｜x｜n） ~ 〈n｜V＇（x）x^2｜n〉 ＋ 4〈n｜V（x）x｜n〉 =0 （k=3）. The latter two formulas can be used directly to calculate the energy levels. We present useYul explicit relations for some well known physical potentials without requiring the energy spectra of quantum system.展开更多
文摘Temperature is a key factor that shapes the distribution of organisms.Having knowledge about how species respond to temperature is relevant to devise strategies for addressing the impacts of climate change.Aquatic insects are particularly vulnerable to climate change,yet there is still much to learn about their ecology and distribution.In the Yungas ecoregion of Northwestern Argentina,cold-and warm-adapted species of the orders Ephemeroptera,Plecoptera,and Trichoptera(EPT)are segregated by elevation.We modeled the ecological niche of South American EPT species in this region using available data and projected their potential distribution in geographic space.Species were grouped based on their ecogeographic similarity,and we analyzed their replacement pattern along elevation gradients,focusing on the ecotone where opposing thermal preferences converge.Along this interface,we identified critical points where the combined incidence of cold and warm assemblages maximizes,indicating a significant transition zone.We found that the Montane Cloud Forest holds the interface,with a particularly greater suitability at its lower boundary.The main axis of the interface runs in a N-S direction and falls between 14°C-16°C mean annual isotherms.The probability of a particular location within a basin being classified as part of the interface increases as Kira’s warmth index approaches a score around 150.Understanding the interface is critical for defining the thermal limits of species distribution and designing biomonitoring programs.Changes in the location of thermal constants related to mountainous ecotones may cause vertical displacement of aquatic insects and vegetation communities.We have recognized significant temperature thresholds that serve as indicators of suitability for the interface.As global warming is anticipated to shift these indicators,we suggest using them to monitor the imprints of climate change on mountain ecosystems.
基金the University of Guanajuato, Mexico and the Program for Teacher-Professional Development (PRODEP), Guanajuato of Mexico (No. NPTC UG-PTC-571) for financial support
文摘In recent years,there has been an increasing interest in finding sustainable strategies for the efficient removal of contaminants from soils.The objective of this review is to examine the biochemical principles of specific genetic modifications in plants,their applications in the field for specific contaminants as phytotechnologies,and their international regulation.In addition,the review presents some biological aspects of rhizosphere-related phenomena,the interactions of organic and inorganic pollutants with plants,and the performance of the phytotechnologies across the continents.During the last few decades,at least eight genera of genetically modified plants(GMPs)have been tested and used for soil remediation with outstanding results.Arabidopsis,Nicotiana,and Oryza are the plant genera most widely studied.Specific plant genes such as metal transporters,chelators,metallothioneins,phytochelatins,and oxygenases have been transferred to plants to improve the elimination of contaminants in soil.We discuss some important aspects of gene manipulation and its application for removal of diverse contaminants.A key challenge faced by phytotechnologies is the final disposal of the generated biomass,from a safety aspect.We argue that the commercial success of phytotechnologies depends on the generation of valuable biomass on contaminated land and its use for bioenergy generation.The use of such technologies would promote a broader understanding of the importance of plants,especially GMPs,in the environment and their contribution to environmental sustainability.
基金financially supported by NEMAK S.A. and Industria Meccanica Bassi Luigi&Co
文摘This paper presents the erosion results of the AISI H13 steel impinged by resin-bonded silica sand, using a testing rig that closely simulates the real blowing conditions during industrial core-making. Steel specimens were heat treated to obtain hardness of 294, 445 and 595 HV200 (29, 45 and 55 HRC). Erosion tests were carried out at impingement angles from 20° to 90° and air drag pressures of 1.38, 2.07 and 2.76 bar (20, 30 and 40 psi). The main results are summarized as follows:(i) The harder material, the lower erosion;(ii) the maximum erosion rate is at 30°;(iii) Little difference in erosion rate at impact angle of 60° and 90° for a constant pressure tested regardless of the hardness level;(iv) As the pressure increases, so does the erosion rate, being more sensitive for low impact angles. Finally, a differential form of the general erosion equation is applied on a practical core-making case to evaluate the erosion rate of the H13 steel at 30° and 90° impingement angles.
基金supported by the Mexican Institute of Water Technology(Grant No.DP2101.1)the Catedras-CONACyT Program of the National Council of Science and Technology(Project No.159).
文摘Fe_(3)O_(4)magnetic xerogel composites were prepared by polycondensation of resorcinol(R)-formaldehyde reaction via a sol-gel process in an aqueous solution through varying the molar ratio of Fe_(3)O_(4)nanoparticles(MNPs),catalyst(C),and water(W)content.MNPs were obtained by co-precipitation(MC),oxidation of iron salts(MO),or solvothermal synthesis(MS).Both MNPs and magnetic xerogels were examined regarding the performance of arsenic and fluoride removal in a batch system.The MC-based MNPs had higher adsorption capacities for both fluoride(202.9 mg/g)and arsenic(3.2 mg/g)than other MNPs in optimum conditions.The X-ray diffraction,Fourier transform infrared spectroscopy,and energy-dispersive X-ray spectroscopy confirmed that Fe was composed into the polymeric matrix of magnetic xerogels that contained 0.59%-4.42%of Fe with a molar ratio of MNPs(M)to R between 0.01 and 0.10.With low R/C and optimum M/R ratios,an increase in the surface area of magnetic xerogels affected the fluoride and arsenic adsorption capacities.The magnetic xerogel composites with the MC-based MNPs prepared at a fixed R/C ratio(100)and at different R/W(0.05-0.06)and M/R(0.07-0.10)ratios had a high arsenic removal efficiency of 100%at an As(V)concentration of 0.1 mg/L and pH of 3.0.The maximum adsorption capacities of magnetic xerogels were approximately five times higher than those of the xerogels without MNP composites.Therefore,Fe_(3)O_(4)nanoparticles enhanced the adsorption of arsenate and fluoride.The variations of alkaline catalyst and water content significantly affected the resulting properties of textural and surface chemistry of magnetic xerogel composites.
基金financially supported by the Natural Science Foundation of Hubei Province of China (No.2016CFA013)the Wuhan Science and Technology Bureau of China (No.2016070204020156)the Consejo Nacional de Ciencia y Tecnología (CONACYT) of Mexico (No.270186)
文摘In saline water flotation, the salinity can cause a distinguishable slime coating of clay minerals on chalcopyrite particles through its effect on their electrical double layers in aqueous solutions. In this work, kaolinite was used as a representative clay mineral for studying slime coating during chalcopyrite flotation. The flotation of chalcopyrite in the presence and absence of kaolinite in tap water, seawater, and gypsum-saturated water and the stability of chalcopyrite and kaolinite particles in slurries are presented. Zeta-potential distributions and scanning electron microscopy images were used to characterize and explain the different slime coating degrees and the different flotation performances. Kaolinite particles induced slime coating on chalcopyrite surfaces and reduced chalcopyrite floatability to the greatest extent when the p H value was in the alkaline range. At 0.24 wt% of kaolinite, the chalcopyrite floatability was depressed by more than 10% at alkaline p H levels in tap water. Salinity in seawater and gypsum-saturated water compressed the electrical double layers and resulted in extensive slime coating.
基金the National Council of Science and Technology of Mexico(CONACYT)for the Ph.D.scholarship(No.788678)receivedthe use of the equipment acquired with the support for projects Nos.235780,271878,and 282357 of the National Laboratory SEDEAM-CONACYT.
文摘A microstructural analysis was performed to determine the presence of oxygen in a wire rod section of AISI 1008 steel with a surface mechanical failure produced during wire drawing.The failure zone was analyzed by comparison using three different attack reagents:alkaline sodium chromate(ASC),ASC with hydrogen peroxide and amyl alcohol,and a solution of nitric acid in ethyl alcohol.The reagents were applied in samples in the failure zone,showing different types of zones in regions with internal and superficial defects such as carbides,pores,cracks,deformation,and detachment zones,indicating the possible presence of oxygen.The areas identified were observed by means of an optical microscope and were correlated with the content of elements that were present in the region using a scanning electron microscope and a scattered X-ray energy spectrometer,which determined that the areas identified by chromate sodium correspond to regions with a high concentration of oxygen and slag-forming elements such as silicon,aluminum,and iron;this is associated with the presence of oxygen in the oxide form.It was also observed that the ASC and the modified ASC solution with hydrogen peroxide and amyl alcohol could identify areas with a high presence of oxides,while the nitric acid solution only identified the steel microstructure.The modified ASC solution is an alternative to identify the presence of chemical variants of oxygen because the conventional formulation is unstable and has a too short shelf life,and therefore,its application must be carried out at the time of preparation.
文摘A numerical simulation was performed to study the flow pattern,mixing time and open-eye slag produced by argon gas injection in an industrial scale steel ladle under non-isothermal conditions.The liquid steel remains 5min before the injection,and thermal stratification and convective flows were analyzed.Three different sequences in stages employing various argon-gas flow rates were simulated.In the first case,a sequence with the highest flow rates of argon was applied,while in the second and the third sequences,the intermediate and the lowest flow rates of argon gas were used,respectively.For determining the chemistry homogenization,the mixing time was computed and analyzed in all three cases.It was found that the cold steel is located near the walls while the steel with a high temperature is accumulated in the center of the ladle above the argon-gas tuyere.The higher and lower flows promote a faster chemistry homogenization owing to the secondary recirculations that are developed closer to the walls.The results from steel temperature drop show a good concordance with plant trial measurements.
基金This research was supported by Comunidad de Nuevo San Juan Parangaricutiro in Michoacan state.
文摘Assisted migration has been proposed as a strategy for adaptive management of forest species in response to expected effects of climate change,but it is controversial for several reasons.Tropical dry forests are among the most threatened ecosystems in the world.In Mexico,historically,land-use change and deforestation have been decreasing forest cover,and climate change is shifting the potential distribution of different forest types,exacerbating the risk of local extinctions.Assisted altitudinal migration could be a feasible strategy for reducing local extinctions in response to climate change and lack of landscape connectivity.Our objective was to evaluate survival and growth of Albizia plurijuga and Ceiba aesculifolia,two tropical deciduous forests species in Mexico.We transplanted 4-month-old seedlings to experimental raised beds at three altitudes(2100,2400 and 2700 m a.s.l.),exceeding their upper regional limit of distribution(2000 m a.s.l.).We also tested seed germination at each altitude.We monitored the experiment for 10 months.For both species,as altitude increased and cold weather was more prevalent,plant performance declined.Within species,differences in individual growth were significant among altitudes.Overall survival was 18.5%for A.plurijuga and 24.5%for C.aesculifolia.Both species had higher survival and better growth at lower altitude,and no seedling emergence at any altitude.We conclude that assisted migration can be implemented for each species by an upward attitudinal shift within,and not exceeding,400 m beyond their present upper altitudinal limit of distribution.Our results indicate that for many species that show altitudinal gradients at regional scales,unless current climate conditions change,the potential to establish outside their range is minimal.
文摘The high mortality rate of breast cancer is mainly caused by the metastatic ability of cancer cells,resistance to chemotherapy and radiotherapy,and tumor regression capacity.In recent years,it has been shown that the presence of breast cancer stem cells is closely associated with the migration and metastatic ability of cancer cells,as well as with their resistance to chemotherapy and radiotherapy.The tumor microenvironment is one of the main molecular factors involved in cancer and metastatic processes development,in this sense it is interesting to study the role of platelets,one of the main communicator cells in the human body which are activated by the signals they receive from the microenvironment and can generate more than one response.Platelets can ingest and release RNA,proteins,cytokines and growth factors.After the platelets interact with the tumor microenvironment,they are called"tumor-educated platelets."Tumor-educated platelets transport material from the tumor microenvironment to sites adjacent to the tumor,thus helping to create microenvironments conducive for the development of primary and metastatic tumors.It has been observed that the clone capable of carrying out the metastatic process is a cancer cell with stem cell characteristics.Cancer stem cells go through a series of processes,including epithelial-mesenchymal transition,intravasation into blood vessels,movement through blood vessels,extravasation at the site of the establishment of a metastatic focus,and site colonization.Tumor-educated platelets support all these processes.
基金supported by Universidad Autónoma de San Luis Potosi, Centro de Investigación en Materiales Avanzados Unidad Chihuahua and Universitat Politècnica de CatalunyaFinancial support by CONACYT is appreciatedfinancial support from FAI-UASLP under the project CI5-FAI-04-45.45
文摘The powders of the AA 7075-ZRO2 were mixed by mechanical milling, but it was found that the system presents a few disadvantages when processed by conventional sintering and hot extrusion, since intermetallic phases between ZrO2 particles and alloying elements were formed. Equal channel angular pressing （ECAP） processing was proposed as an alternative method to consolidate the composite where there is no intermetallic formation. The analysis of the ECAP process showed that the intermediate temperature （220℃） produced a higher consolidation level than conventional sintering and hot extrusion （400 and 500℃, respectively）. This fact was supported by relative density analysis. In the case of the sintered and hot-extruded sample, the relative density exhibited a value of 0.95, while ECAP sample showed a value of 0.98. Hardness values show that microstructural refinement obtained during mechanical milling was preserved during ECAP processing even when it was carded out at 220℃.
文摘AIM To determine a potential relationship between serum undercarboxylated(uc OC) concentration and cardiovascular risk factors in type 2 diabetes(T2D) patients and healthy subjects(HS).METHODS A cross-sectional study was conducted on 140 subjects classified into two groups, 70 with T2D and 70 HS. Medical history and physical examination with anthropometric measurements were obtained from all subjects. Body fat percentage was determined by bioelectrical impendency analysis. Serum uc OC concentration was determined by enzyme immunoassay,while serum levels of insulin and hsC RP were obtained using high sensitivity enzyme-linked immunosorbent assay. Insulin resistance was determined using the homeostasis model assessment-IR. Lipid profile [triglycerides,total cholesterol(TC), high-density lipoproteins(HDL-c),low density lipoproteins(LDL-c), very low-density lipoproteins] was determined by spectrophotometry and standard formulas when applicable. RESULTS The T2D patient group showed significantly higher values of waist circumference, waist-to-hip ratio, systolic blood pressure(SBP), diastolic blood pressure(DBP),current smoking, and alcohol use when compared to the HS group(P < 0.05). We observed a significantly lower serum ucO C concentration in T2D than in HS(1.5 ± 1.4vs 2.3 ± 1.8, P < 0.05). In the whole study population,ucO C concentration was inversely correlated with body mass index(BMI)(r =-0.236, P < 0.05), fasting plasma glucose(r =-0.283, P < 0.01) and HDL-c(r =-0.255,P < 0.05); and positively correlated with LDL-c/HDL-c ratio(r = 0.306, P < 0.05) and TC/HDL-c ratio(r =0.284, P < 0.05). In the T2D group, serum uc OC concentration was inversely correlated with BMI(r =-0.310, P < 0.05) and body-fat percentage(r =-0.311,P < 0.05), and positively correlated with DBP(r = 0.450,P < 0.01). In HS group a positive correlation between serum levels of uc OC and SBP(r = 0.277, P < 0.05)was observed. CONCLUSION Serum uc OC is a potential marker for cardiovascular risk in Mexicans because it is related to adiposity parameters, blood pressure and lipid profile.
基金CONACYT(771343,700755,250910,251526,researcher number 1640,project number 1781).
文摘Background:Among urban stimuli,anthropogenic noise has been identified to be one of the behavioral drivers of species that rely on acoustic signals for communication.Studies have shown both species‑specific and assemblage responses to urban noise,ranging from the modulation of their acoustic frequencies and spatiotemporal adjustments to declines in species richness.In this study,we assessed the citywide relationship between two anthropogenic noise variables(noise levels recorded during bird surveys and daily average noise levels)and vegetation cover with bird species richness.Methods:This study was conducted in the city of Xalapa(Mexico)through a 114 citywide point‑count survey.We recorded bird communities at each sampling site.We measured noise levels using a sound level meter while performing point‑counts.Then,we generated a map of average daily noise of the city using an array of 61 autonomous recording units distributed across the city of Xalapa and calculated daily noise levels for the 114 points.We ran a linear model(LM)to assess potential relationships between both point‑count and daily(24 h)noise values and vegetation cover with bird richness.Results:Results from the LM show:(1)a negative relationship between maximum point‑count noise and avian species richness,(2)no relationship between 24 h noise and bird species richness,and(3)a positive relationship between vegetation cover and bird species richness.Conclusions:Results provide evidence that decreases in urban bird species richness do not necessarily imply the permanent absence of species,suggesting that birds can temporarily fly away from or avoid sites when noisy,become cryptic while noisy events are occurring,or be undetected due to our inability to record them in the field during noisy events.
基金Supported by the project under Grant No.20180677-SIP-IPN,COFAA-IPN,Mexicopartially by the CONACYT project under Grant No.288856-CB-2016
文摘In this work we study the quantum system with the symmetric Konwent potential and show how to find its exact solutions. We find that the solutions are given by the confluent Heun function. The eigenvalues have to be calculated numerically because series expansion method does not work due to the variable z ≥ 1. The properties of the wave functions depending on the potential parameter A are illustrated for given potential parameters V_0 and a. The wave functions are shrunk towards the origin with the increasing |A|. In particular, the amplitude of wave function of the second excited state moves towards the origin when the positive parameter A decreases. We notice that the energy levels ε_i increase with the increasing potential parameter |A| ≥ 1, but the variation of the energy levels becomes complicated for |A| ∈(0, 1), which possesses a double well. It is seen that the energy levels ε_i increase with |A| for the parameter interval A ∈(-1, 0), while they decrease with |A| for the parameter interval A ∈(0, 1).
文摘Background:Studies on the relationship between biodiversity and ecosystem productivity have suggested that species richness and functional diversity are the main drivers of ecosystem processes.Several patterns on this relationship have been found,including positive,unimodal,negative,and neutral trends,keeping the issue controversial.In this study,taxonomic diversity and functional diversity as drivers of above-ground biomass(AGB)were compared,and the mechanisms that influence biomass production were investigated by testing the complementarity and the mass-ratio hypotheses.Methods:Using data from 414 permanent sample plots,covering 23%of temperate forest in the Sierra Madre Oriental(México),we estimated the above-gound biomass(AGB),taxonomic and functional diversity indices,as well as community weighted mean values(CWM)for three functional traits(maximum height,leaf size and wood density)for trees≥7.5 cm DBH,in managed and unmanaged stands.To compare taxonomic diversity differences between managed and unmanaged stands we carried out a rarefaction analysis.Furthermore,we evaluated the relationship between AGB and taxonomic and functional diversity metrics,as well as CWM traits throught spatial autoregressive models.Results:We found a hump-shaped relationship between AGB and species richness in managed and unmanaged forests.CMW of maximum height was the most important predictor of AGB in both stands,which suggested that the mechanism underlaying the AGB-diversity relationship is the dominance of some highly productive species,supporting the mass-ratio hypothesis.Above-ground biomass was significantly correlated with three of the five functional diversity metrics,CWM maximum height and species richness.Our results show the importance of taking into account spatial autocorrelation in the construction of predictive models to avoid spurious patterns in the AGBdiversity relationship.Conclusion:Species richness,maximum height,functional richness,functional dispersion and RaoQ indices relate with above-ground biomass production in temperate mixed-species and uneven-aged forests of northern Mexico.These forests show a hump-shaped AGB-species richness relationship.Functional diversity explains better AGB production than classical taxonomic diversity.Community weighted mean traits provide key information to explain stand biomass in these forests,where maximum tree height seems to be a more suitable trait for understanding the biomass accumulation process in these ecosystems.Although the impact of forest management on biodiversity is still debated,it has not changed the AGB-diversity relationships in the forests of the Sierra Madre Occidental,Mexico.
基金partially supported by the 20210414-SIPIPN, Mexico。
文摘Using a single-mode approximation, we carry out the entanglement measures, e.g., the negativity and von Neumann entropy when a tetrapartite generalized GHZ state is treated in a noninertial frame, but only uniform acceleration is considered for simplicity. In terms of explicit negativity calculated, we notice that the difference between the algebraic average π_(4) and geometric average Π_(4) is very small with the increasing accelerated observers and they are totally equal when all four qubits are accelerated simultaneously. The entanglement properties are discussed from one accelerated observer to all four accelerated observers. It is shown that the entanglement still exists even if the acceleration parameter r goes to infinity. It is interesting to discover that all 1-1 tangles are equal to zero, but 1-3 and 2-2 tangles always decrease when the acceleration parameter γ increases. We also study the von Neumann entropy and find that it increases with the number of the accelerated observers. In addition, we find that the von Neumann entropy S_(ABCDI), S_(ABCIDI), S_(ABICIDI) and S_(AIBICIDI) always decrease with the controllable angle θ, while the entropies S_(3-3 non), S_(3-2 non), S_(3-1 non) and S_(3-0 non) first increase with the angle θ and then decrease with it.
基金Supported by the CONACYT of Mexico under Grant No 288856-CB-2016,and the 20190234-SIP-IPN of Mexico
文摘Using the single-mode approximation,we study entanglement measures including two independent quantities;i.e.,negativity and von Neumann entropy for a tripartite generalized Greenberger-Horne-Zeilinger(GHZ)state in noninertial frames.Based on the calculated negativity,we study the whole entanglement measures named as the algebraic average π3-tangle and geometric average Π3-tangle.We find that the difference between them is very small or disappears with the increase of the number of accelerated qubits.The entanglement properties are discussed from one accelerated observer and others remaining stationary to all three accelerated observers.The results show that there will always exist entanglement,even if acceleration r arrives to infinity.The degree of entanglement for all 1-1 tangles are alwa.ys equal to zero,but 1-2 tangles always decrease with the acceleration parameter r.We notice that the von Neumann entropy increases with the number of the accelerated observers and SκΙζΙ(κ,ζ∈(A,B,C)) first increases and then decreases with the acceleration parameter r.This implies that the subsystem ρκΙζΙ is first more disorder and then the disorder will be reduced as the acceleration parameter r increases.Moreover,it is found that the von Neumann entropies SABCI,SABICI and SAIBICI always decrease with the controllable angle θ,while the entropies of the bipartite subsystems S2-2non(two accelerated qubits),S2-1non(one accelerated qubit) and S2-0non(without accelerated qubit) first increase with the angle θ and then decrease with it.
文摘Efforts to improve crop yields with efficient use of fertilizers are needed to guarantee global food security.Enhanced slow-release fertilizer systems(SRFs)encapsulated in biodegradable matrices are being developed to address this global concern.From a wide range of strategies for SRFs development,we explored a natureinspired solution based on the plant cuticle model and its function as a membrane for water and nutrient transport control.Here,Candelilla wax,extracted from Candelilla wild plants(Euphorbia antisyphilitica),is studied as a renewable slow-release matrix for fertilizers encapsulated by a modified spray chilling process.From this process,microencapsulates containing 40 wt%of phosphorus fertilizer are obtained with distinctive sizes and chemical characteristics,presenting a slow-release behavior.Considering the abovementioned features,novel insights into fertilizer release mechanisms based on plant cuticle models are discussed.
基金Project supported by the Iranian Nanotechnology Initiative Council(INIC)the 20180677-SIP-IPN,Mexicothe CONACYT 288856-CB-2016,Mexico
文摘We first study the Shannon information entropies of constant total length multiple quantum well systems and then explore the effects of the number of wells and confining potential depth on position and momentum information entropy density as well as the corresponding Shannon entropy.We find that for small full width at half maximum（FWHM） of the position entropy density,the FWHM of the momentum entropy density is large and vice versa.By increasing the confined potential depth,the FWHM of the position entropy density decreases while the FWHM of the momentum entropy density increases.By increasing the potential depth,the frequency of the position entropy density oscillation within the quantum barrier decreases while that of the position entropy density oscillation within the quantum well increases.By increasing the number of wells,the frequency of the position entropy density oscillation decreases inside the barriers while it increases inside the quantum well.As an example,we might localize the ground state as well as the position entropy densities of the1 st,2 nd,and 6 th excited states for a four-well quantum system.Also,we verify the Bialynicki–Birula–Mycieslki（BBM）inequality.
基金Supported in part by Project 20150964-SIP-IPN,COFAA-IPN,Mexico
文摘Based on a Hamfltonian identity, we study one-dimensional generalized hypervirial theorem, Blanchardlike （non-diagonal case） and Kramers＇ （diagonal case） recurrence relations for arbitrary x^k which is independent of the central potential V（x）. Some significant results in diagonal case are obtained for special k in xk （k ≥2）. In particular, we find the orthogonal relation 〈n1｜n2〉 = δh1,n2 （k = 0）, 〈n1[V＇（x）｜n2〉 = （En1-En2）^2〈n1｜x｜n2〉 （k = 1）, En = （n｜V＇（x）x/2｜n〉 ＋ （n｜V（x）｜n〉 （k = 2） and -4En（n｜x｜n） ~ 〈n｜V＇（x）x^2｜n〉 ＋ 4〈n｜V（x）x｜n〉 =0 （k=3）. The latter two formulas can be used directly to calculate the energy levels. We present useYul explicit relations for some well known physical potentials without requiring the energy spectra of quantum system.
