Mo_(2)P Monolayer as a Superior Electrocatalyst for Urea Synthesis from Nitrogen and Carbon Dioxide Fixation:A Computational Study

Urea synthesis through the simultaneous electrocatalytic reduction of N_(2)and CO_(2)molecules under ambient conditions holds great promises as a sustainable alternative to its industrial production,in which the development of stable,highly efficient,and highly selective catalysts to boost the chemisorption,activation,and coupling of inert N_(2)and CO_(2)molecules remains rather challenging.Herein,by means of density functional theory computations,we proposed a new class of two-dimensional nanomaterials,namely,transition-metal phosphide monolayers(TM_(2)P,TM=Ti,Fe,Zr,Mo,and W),as the potential electrocatalysts for urea production.Our results showed that these TM_(2)P materials exhibit outstanding stability and excellent metallic properties.Interestingly,the Mo_(2)P monolayer was screened out as the best catalyst for urea synthesis due to its small kinetic energy barrier(0.35 eV)for C-N coupling,low limiting potential(-0.39 V),and significant suppressing effects on the competing side reactions.The outstanding catalytic activity of the Mo_(2)P monolayer can be ascribed to its optimal adsorption strength with the key^(*)NCON species due to its moderate positive charges on the Mo active sites.Our findings not only propose a novel catalyst with high-efficiency and high-selectivity for urea production but also further widen the potential applications of metal phosphides in electrocatalysis.

A new boundary element solution to evaluate the geometric effects of the canyon site on the displacement response spectrum

This paper presents a step-by-step procedure using the three-dimensional boundary element approach to study the behavior of semi-circular canyons under seismic shear waves. The boundary element code TDASC allows utilization for various canyon geometries, evaluation of concurrent seismic waves and calculation of the ground motions on canyons due to an excitation at any arbitrary point of the incident field. Considering the widening ratio of the canyon(including prismatic, semi-prismatic and non-prismatic canyons), wave characteristics(wavelength, dimensionless period, direction) and maximum amplification pattern, the solution was applied to carry out a series of parametric studies. It was shown that canyon form can significantly affect the displacement amplification, especially at the points located on its edges. By increasing the wave dimensionless frequency(η > 1), the amplification pattern becomes more complex. On the basis of the results from a variety of considered cases, a new expression has been presented for the limiting wavelength beyond which the widening of the canyon will not have a major effect on the displacement amplification. To verify the reliability of the proposed approach, the obtained results, expressed in terms of displacement amplitude, were compared with those from the available published literature and a reasonably good agreement was observed.

Feasibility of using electrokinetics and nanomaterials to stabilize and improve collapsible soils

Loess as a subcategory of collapsible soils is a well-known aeolian deposit generally characterized as a highly-porous medium with relatively low natural density and water content and a high percentage of fine-grained particles.Such collapsible soil sustains large stresses under a dry condition with natural water content.However,it can experience high and relatively sudden decreases in its volume once it reaches a certain water content under a certain load and therefore,the natural condition of the soil might not be suitable for construction if the possibility of the exposure of the soil to excessive water exists during the lifetime of the project.This research presents the utilization of an innovative method for stabilization and improvement of Gorgan loessial soil.This method uses electrokinetics and nanomaterials to instigate additives to move through soil pores,as an in situ remedial measure.To assess the acceptability of this measure,the deformability and strength characteristics of the improved collapsible soil are measured and compared with those of the unimproved soil,implementing several unsaturated oedometer tests under constant vertical stress and varying matric suction.The result emphasizes the importance of the matric suction on the behavior of both improved and unimproved soils.The test results indicate that the resistance of the soil was highly dependent on the water content and matric suction of the soil.The oedometer tests on samples improved by 3%lime and 5%nanomaterials show considerable improvement of the collapse potential.Results also reveal that stabilized samples experience notably lower volume decrease under the same applied stresses.

Single-atom catalysts with anionic metal centers: Promising electrocatalysts for the oxygen reduction reaction and beyond

Ongoing efforts to develop single-atom catalysts(SACs) for the oxygen reduction reaction(ORR) typically focus on SACs with cationic metal centers,while SACs with anionic metal centers(anionic SACs) have been generally neglected.However,anionic SACs may offer excellent active sites for ORR,since anionic metal centers could facilitate the activation of O_(2) by back donating electrons to the antibonding orbitals of O_(2).In this work,we propose a simple guideline for designing anionic SACs:the metal centers should have larger electronegativity than the surrounding atoms in the substrate on which the metal atoms are supported.By means of density functional theory(DFT) simulations,we identified 13 anionic metal centers(Co,Ni,Cu,Ru,Rh,Pd,Ag,Re,Os,Ir,Pt,Au,and Hg) dispersed on pristine or defective antimonene substrates as new anionic SACs,among which anionic Au and Co metal centers exhibit limiting potentials comparable to,or even better than,conventional Pt-based catalysts towards ORR.We also found that anionic Os and Re metal centers on the defective antimonene can electrochemically catalyze the nitrogen reduction reaction(NRR) with a limiting potential close to that of stepped Ru(0001).Overall,our work shows promise towards the rational design of anionic SACs and their utility for applications as electrocatalysts for ORR and other important electrochemical reactions.

Label-free imaging immune cells and collagen in atherosclerosis with two-photon and second harmonic generation microscopy

Atherosclerosis has been recognized as a chronic inflammation disease,in which many types of cells participate in this process,including lymphocytes,macrophages,dendritic cells(DCs),mast cells,vascular smooth muscle cells(SMCs).Developments in imaging technology provide the capability to observe cellular and tissue components and their interactions.The knowledge of the functions of immune cells and their interactions with other cell and tissue components will facilitate our discovery of biomarkers in atherosclerosis and prediction of the risk factor of rupture-prone plaques.Nonlinear optical microscopy based on two-photon excited autofluorescence and second harmonic generation(SHG)were developed to image mast cells,SMCs and collagen in plaque ex vivo using endogenous optical signals.Mast cells were imaged with two-photon tryptophan autofluorescence,SMCs were imaged with two-photon NADH auto fluorescence,and collagen were imaged with SHG.This development paves the way for further study of mast cell degranulation,and the effects of mast cell derived mediators such as induced synthesis and activation of matrix metalloproteinases(MMPs)which participate in the degradation of collagen.

Remarkably Consistent Rare Earth Element Grades at Round Top Yttrofluorite Deposit

The peraluminous rhyolite that forms Round Top Mountain (approximately 375 m high × nearly 2 km in diameter), near Sierra Blanca, Hudspeth County, west Texas, USA, is enriched in yttrium and heavy rare earth elements (YHREEs), as well as Li, Be, U, Th, Sn, F, Rb, Cs, Nb, and Ta. Texas Mineral Resources Corp. (USA) proposes to release the YHREEs from their unique yttrofluorite host via heap leaching with dilute sulfuric acid. The inexpensive process also releases portions of valuable byproduct Be, Li, and U from accessory minerals amid the insoluble feldspars and quartz that comprise 90% - 95% of the surface-exposed rhyolite mountain. The objective of this study is to determine the consistency of mineralization grade, an important consideration in mine planning and preliminary economic analysis. The method is to plot elemental analyses of Y, Dy, Ho, Tm, Yb, Ce, Pr, Nd, Eu, Gd, Tb, U, and Nb from more than 1400 reverse circulation cuttings taken from 64 exploration drill holes against sample depth. The result of inspection of the plots reveals a remarkably homogeneous distribution of minor and trace elements throughout the sampled portion of the massive, 1.6-billion-tonne laccolith. The plots drive the conclusion that Round Top mine feedstock should remain constant for the life of the mine (multiple decades). Thus mining mechanics could be optimized at the start of operations and not require expensive later changes. The physical and chemical design of the heap leach and recovery and purification of target elements from pregnant leach solution also could be perfected during early development.

Effect of pipe characteristics in umbrella arch method on controlling tunneling-induced settlements in soft grounds

Recent developments in tunneling have stimulated design practitioners to more effectively utilize the underground spaces.However,tunneling at shallow depth in soft grounds gives rise to concerns associated with tunnel instability.Umbrella arch method(UAM),as a pre-reinforcement approach of tunnels in complex geological conditions,is widely used to maintain the tunnel stability.Quantitative assessment of the impacts of the entire approach and forepoling pipe features on tunnel stability remains challenging due to the complex nature of the UAM application.This study aimed to assess the effect of pipe design parameters on reinforcing the tunnels excavated in soft grounds.This practical investigation considered the actual field conditions attributed to the tunneling procedure and UAM deployment.Then,the tunneling process was modeled and the tunnel excavation-induced settlements were calculated.The post-processed results confirmed that deploying the UAM substantially reduced the tunnel crown and ground surface settlements by 76%and 42%,respectively.Investigation of various design parameters of pipes underscored the significance of incorporating the optimum value for each individual parameter into design schemes to more effectively control the settlements.Additionally,contrasting the settlement reduction rates(SRRs)for pipe design variables showed that the tunnel stability is more sensitive to the changes in the values of diameter and length,compared to values of the installation angle and center-tocenter distance of the pipes.

Equitable bivalent booster allocation strategies against emerging SARS-CoV-2 variants in US cities with large Hispanic communities:The case of El Paso County,Texas

COVID-19 is a disease that disproportionately impacts the Hispanic population,due to the prevalence of certain risk factors and the high number of essential workers in this com-munity.In this work,we analyze the vaccination strategies that would minimize the COVID-19 health disparities in El Paso County,TX,in the context of the emergence of a new highly transmissible and immune-escaping SARS-CoV-2 variant.We stratify an age-structure stochastic SEIR model that tracks the evolution of immunity derived from in-fections and vaccination according to Hispanic vs non-Hispanic ethnicity and parameterize it to the demographic,health and immunization data of El Paso County,TX.After fitting the model,the results show that increasing vaccination with bivalent boosters by five-fold in anticipation of highly transmissible and immune escaping variants would decrease the cumulative hospital admissions and mortality from Mar 1,2023,to Dec 31,2023,by 62.72%and 61.41%,respectively.Further,our projections reveal that the disproportionate impact on the Hispanic community would be eliminated if approximately half of the doses that are given to the non-Hispanic group according to the equal distribution,would be re-allocated to the Hispanic population.Our findings can guide public health officials in US cities with large Hispanic communities and help them design vaccination strategies that minimize COVID-19 health disparities caused by emerging variants using specific vacci-nation strategies.

Self-Organizing Maps in Seismic Image Segmentation

Unsupervised neural networks such as the Kohonen Self-Organizing Maps （SOM） have been widely used for searching natural clusters in multidimensional and massive data. One example where the data available for analysis can be extremely large is seismic interpretation for hydrocarbon exploration. In order to assist the interpreter in identifying characteristics of interest confined in the seismic data, the authors present a set of data attributes that can be used to train a SOM in such a way that zones of interest can be automatically identified or segmented, reducing time in the interpretation process. The authors show how to associate SOM to 2D color maps to visually identify the clustering structure of the input seismic data, and apply the proposed technique to a 2D synthetic seismic dataset of salt structures.

Microprobe Mapping of Rare Earth Element Distribution in Round Top Yttrofluorite Deposit

The electron microprobe maps the spatial distribution of elements in a rock at a sub-mineral-grain scale to provide a basis for understanding mineralization processes and to determine optimal strategies for extraction of valuable target elements. Round Top Mountain (near the town of Sierra Blanca, Hudspeth County, west Texas, USA) is a peraluminous rhyolite laccolith that is homogeneously mineralized at over 500 ppm rare earths, more than 70% of which are yttrium and heavy rare earths (YHREEs). The massive deposit is exposed at the surface as a mountain some 2 km in diameter and 375 m in height. Round Top Mountain also contains Li, Be, U, Th, Nb, Ta, Ga, Rb, Cs, Sn, and F. The valuable YHREEs are hosted in yttrofluorite, which is soluble in dilute sulfuric acid. Texas Mineral Resources Corporation proposes to surface mine, crush, and heap leach the deposit. The distribution of YHREEs, and that of other trace elements, is remarkably homogeneous at outcrop drill hole scale. Here we document that YHREE mineralization appears pervasive through the rhyolite at a millimeter scale. Back scattered electron (BSE) and characteristic X-ray maps reveal the fine grain size and apparently random and dispersed spatial distribution of the yttrofluorite that hosts Round Top’s valuable YHREEs. The yttrofluorite grains do not appear to cluster at special mineralized locations, e.g., in pores or along cracks in the rhyolite. The same is apparently true of such other potentially valuable minerals as cassiterite and uranium species. These findings confirm that the distribution of YHREEs in Round Top Mountain rhyolite is homogeneous through different orders of magnitude of scale, i.e., from outcrop (as seen in the companion work in this volume) to sub-thin section. The material thus is ideal for a heap leach operation where homogeneous feedstock is crucial to consistent and economic operation. The findings also confirm and explain why mechanical separation would prove very difficult and expensive due to the astronomical number of yttrofluorite grains in even a golf-ball-size piece of Round Top rhyolite.

SCADA Framework Incorporating MANET and IDP for Cyber Security of Residential Microgrid Communication Network

This paper presents a reliable and secure supervisory control and data acquisition (SCADA) system equipped with advanced communication technologies (ACT) to enhance the operation and cyber security of the communication network in residential microgrid. The proposed approach uses the mobile ad hoc networks (MANET) for collecting data of power consumption from smart meters of residential areas and electric vehicles (EVs), and also for connecting mobile system operators to the network. Moreover, by understanding the dynamic nature of MANET and their exposure to cyber-attacks, we propose an intrusion detection and prevention (IDP) technology with secure knowledge algorithm and anomaly detection for preventing the black hole attacks, and other unknown attacks that result into packet dropping. Test results obtained by using Network Simulator (NS-2) demonstrate the effectiveness of the proposed IDP technology in preventing the cyber-attacks in the proposed residential microgrid communication network.

Influence of Component Size on the Corrosion Behavior of Ti6Al4V Alloy Fabricated by Electron Beam Powder Bed Fusion

The electrochemical behavior of Ti-6Al-4V with 1 mm and 16 mm thickness prepared by electron beam powder bed fusion(EB-PBF)was investigated in phosphate buffered saline.Electrochemical results showed that EB-PBF Ti-6Al-4V with a larger component size was more resistant to corrosion compared to the smaller component,because of less acicularαʹphase content and moreβphase content.As a non-equilibrium phase in the“high-energy state”,αʹphase has a greater susceptibility to corrode and reduces the corrosion resistance of the material,whileβphase improves corrosion resistance of titanium alloys.The results show that the phase composition has a more significant effect on the corrosion performance than the grain size.

An Approach to Comprehensively Evaluate Potential Park and Ride Facilities

A park and ride facility provides an option to car drivers to park their cars and switch to public transportation for the remaining portions of their trips.Although park and ride has been implemented in many cities in the United States and integrated with different modes of transportation,no comprehensive approach has been developed in published literature to assess the feasibility of a potential park and ride site.This research proposes a comprehensive approach,which consists of the following tasks,to evaluate potential park and ride facilities:1.Site location analysis 2.Bus system reliability analysis 3.Parking supply and usage analysis 4.Mode choice model 5.User demand and ridership estimation 6.Cost estimation and economic impacts analysis The application of the proposed tasks was demonstrated through a case study of a site in the City of El Paso,Texas.

Effects of Crosswalk Location and Pedestrian Volume on Entry Capacity of Roundabouts

At roundabout approaches,vehicles must yield to pedestrians who are using crosswalks.The presence of pedestrians using the crosswalk at a roundabout approach thus decreases the entry capacity of the approach.This research used a calibrated microscopic traffic simulation model to study the effect of crosswalk location and pedestrian volume on the capacity of a two-lane approach entering a two-lane roundabout.The simulation results show that(i)at the same pedestrian volume,the crosswalk located further upstream from the yield line causes a smaller magnitude of reduction in the entry capacity,but there is no significant change in the entry capacity when the crosswalk is beyond three car-length upstream from the yield line;(ii)for the same crosswalk location and conflicting volume,the entry capacity reduces with increasing pedestrian volume,but the marginal reduction diminishes with increasing pedestrian volume.Linear regression equations for entry capacity adjustment factor for pedestrians as a function of conflicting volume have been developed.The adjustment factors are found to be lower than the values provided by the Highway Capacity Manual 2010 which are based on research conducted in Germany.

Electrochemical behavior of open-cellular structured Ti-6Al-4V alloy fabricated by electron beam melting in simulated physiological fluid:the significance of pore characteristics

The cellular structured titanium alloys have attracted significant attention for implants because of their lower Young’s modulus,which is comparable to human bone and has the capability of providing space for bone tissue in-growth.However,there is a gap in the knowledge in regard to the relationship between the pore characteristics and the electrochemical performance of open-cellular structured titanium alloys.In this study,we elucidate the influence of pore characteristics on the electrochemical performance of open-cellular structured Ti-6Al-4V alloys produced by electron beam melting(EBM).Intriguingly,the passive film formed on cellular structured Ti-6Al-4V alloy with a larger pore size was more stable and protective,and the corrosion performance was superior compared to the samples with a smaller pore size in phosphate buffered saline(PBS),mainly because of relatively smaller exposed surface area and unlimited flow of electrolyte.However,in acidic PBS containing fluoride ions,the pore characteristics did not play an important role in the corrosion resistance.It was considered that the protective film breaks down such that the corrosion performance of cellular structured alloys was comparable to each other in this harsh environment.

Neuroprotective effect of antioxidant compounds

Neurodegenerative diseases affect millions of individuals worldwide.It has been estimated that the number of patients affected by neurodegenerative diseases such as Alzheimer’s disease（AD）,Parkinson’s disease（PD）,Huntington’s disease（HD）,

Habitat use in eight populations of Sceloporus grammicus(Squamata:Phrynosomatidae)from the Mexican Plateau

Studies on habitat use have often helped explain observed variation in morphology,behavior and reproductive characteristics among populations within a single species.Here we analyze morphological and ecological characteristics of individuals from the Sceloporus grammicus species complex from 7 different localities(CER,El Cerezo;PAC,Pachuca;HUI,Huichapan;EZA,Emiliano Zapata;SMR,San Miguel Regla;LMJ,La Mojonera;and LMZ,La Manzana)in the state of Hidalgo,and one locality(Cahuacán)in the State of Mexico.A canonical correspondence analysis(CCA)showed that females from PAC,EZA,LMZ,HUI,SMR and CAH populations use similar microhabitats characterized mostly by bare soil,in females from LMJ and CER use microhabitats characterized primarily by vegetation and rocks.Females were observed using 12 different types of perches.With regard to perch height use,the CCA showed that females from PAC,LMJ,LMZ,SMR,CER and CAH populations were correlated with height to nearest perch(HNP),in the rest of the females were not related to any perch use variable.In contrast,the CCA showed that males from PAC,LMJ and CAH were characterized by microhabitats with higher vegetal coverage,while males from LMZ and CER used microhabitats composed of bare soil,but males from HUI and SMR populations used microhabitats composed chiefly of bare soil and rocks.With respect to perch height use,the CCA showed that males from PAC,LMJ,EZA and LMZ were correlated with distance to the nearest perch,but the rest of the males were not correlated with any perch use variables.Males were observed in 9 different perch types.The males were larger than the females in all morphological variables analyzed.Moreover,in both sexes the snout-vent length is positively correlated with all morphological variables,and although both the slope and ordinate of the origin of all morphological variables were larger in males than females,the analysis of covariance indicated that there is no increase in the morphological variables with increasing SVL between sexes.Our results suggest that variation in habitat use and morphology among populations is an adaptive response(phenotypic plasticity)to the environmental conditions where these populations of Sceloporus grammicus occur.

Face Recognition from Incomplete Measurements via <i>l₁</i>-Optimization

In this work, we consider a homotopic principle for solving large-scale and dense l1underdetermined problems and its applications in image processing and classification. We solve the face recognition problem where the input image contains corrupted and/or lost pixels. The approach involves two steps: first, the incomplete or corrupted image is subject to an inpainting process, and secondly, the restored image is used to carry out the classification or recognition task. Addressing these two steps involves solving large scale l1minimization problems. To that end, we propose to solve a sequence of linear equality constrained multiquadric problems that depends on a regularization parameter that converges to zero. The procedure generates a central path that converges to a point on the solution set of the l1underdetermined problem. In order to solve each subproblem, a conjugate gradient algorithm is formulated. When noise is present in the model, inexact directions are taken so that an approximate solution is computed faster. This prevents the ill conditioning produced when the conjugate gradient is required to iterate until a zero residual is attained.

XRF Standardless Comparison of Mining Head and Tail Grades to Screen and Display Ore Processing Recoveries

Separation of target elements or minerals from their host rock or ore is essential to successful mining operation. The inevitable loss of a portion of the desired material that accompanies each step in the extraction process must be documented to develop the operational protocol. Superposition of the characteristic X-ray fluorescence spectra of head (crushed rock ore particles, pre-processing) and tail (post-processing particles) samples provides a direct visual comparison of relative peak sizes, and thereby the relative concentrations, of elements of interest. If the head and tail peaks are identical, none of the element was recovered in the extraction process. At the other extreme if the tail peak “flat lines”, i.e., there is no peak, there was 100% recovery of that element. Standardless visual comparison is valid if the same mass of identical starting material is incorporated into the head and tail sample analysis pucks, and XRF analytical conditions are identical. The considerable time and expense of acquiring and calibrating the standards associated with XRF analysis of 75 or more elements are avoided, a significant advantage during initial broad screening of an experimental extraction procedure. Full quantitation by XRF or an alternate technique can proceed at a later project stage, if desired. The approach retains and presents all features of the original data, thus eliminating questions about data quality, standards and their calibration, and data manipulation in processing from raw counts to concentrations in printout tables. This form of display is ideal for both the mining professional and such less technical groups as corporate staff, investors, regulators, and the public. Examples presented herein are for heap leaching;the protocol can be applied as well to any of the other traditional ore processing and beneficiation procedures, e.g., gravity concentration, magnetic and electrical separation, froth flotation, and ore sorting.

Analysis of Discretionary Lane Changing Parameters on Freeways

A lane changing event,at the instant when a vehicle crosses the lane marker,involves up to five vehicles:the subject vehicle,preceding and following vehicles in the original lane,and the preceding and following vehicles in the target lane.Understanding the interactions of the subject vehicle with the surrounding vehicles is fundamental to the study of the safety and modeling of lane changing behavior.This research studies the statistical properties of 10 lane changing parameters.These parameters describe the gaps,times to collision between vehicles and the subject vehicle’s speed.The parameter values were extracted from the vehicle trajectory data in the Next Generation Simulation data sets.The results show that(i)all the parameters are positively correlated with each other;(ii)the gaps and distance are best described by the lognormal distribution;(ii)the times to collision are best described by the Laplace distribution;(iii)the speed may be described by the log-logistic distribution and the normal distribution.The results suggest that using one or few selected parameters may be sufficient to quantify the risk of a lane changing event.