With the completion of the strategic vision of building a moderately prosperous society in an all-round way in 2020,China’s economic development has entered a new normal.The concept of innovative,coordinated,green,op...With the completion of the strategic vision of building a moderately prosperous society in an all-round way in 2020,China’s economic development has entered a new normal.The concept of innovative,coordinated,green,open and shared development will lead China’s economic progress and development.However,the development of urban and rural areas and regions in China is still not coordinated,and the sudden COVID-19 outbreak has caused a serious impact on urban low-income groups.Due to the characteristics of poor employment stability,low income and single source,as well as greater family pressure of urban low-income groups,the author focuses on the influencing factors of their feelings of happiness.This paper assumes that the satisfaction degree of residents’needs is positively correlated with residents’feelings of happiness.Based on Maslow’s hierarchy of needs theory,this paper analyzes the factors that may affect the happiness of urban low-income groups in five levels,and explores the special needs and difficulties of urban low-income groups in the context of the epidemic.So as to find ways to improve the happiness of urban low-income people to provide reference.展开更多
Tuning the coordination atoms of central metal is an effective means to improve the electrocatalytic activity of atomic catalysts.Herein,iridium(Ir) is proposed to be asymmetrically anchored by sp-N and pyridinic N of...Tuning the coordination atoms of central metal is an effective means to improve the electrocatalytic activity of atomic catalysts.Herein,iridium(Ir) is proposed to be asymmetrically anchored by sp-N and pyridinic N of hydrogen-substituted graphdiyne(HsGDY),and coordinated with OH as an Ir atomic catalyst(Ir_(1)-N-HsGDY).The electron structures,especially the d-band center of Ir atom,are optimized by these specific coordination atoms.Thus,the as-synthesized Ir_(1)-N-HsGDY exhibits excellent electrocatalytic performances for oxygen reduction and hydrogen evolution reactions in both acidic and alkaline media.Benefiting from the unique structure of HsGDY,IrN_(2)(OH)_(3) has been developed and demonstrated to act as the active site in these electrochemical reactions.All those indicate the fresh role of the sp-N in graphdiyne in producing a new anchor way and contributing to promote the electrocatalytic activity,showing a new strategy to design novel electrochemical catalysts.展开更多
Introduction: Measles remains a worrying health problem in sub-Saharan African countries. There have been measles outbreaks in Cameroon with the most recent occurring between October 2022 and September 2023. The Centr...Introduction: Measles remains a worrying health problem in sub-Saharan African countries. There have been measles outbreaks in Cameroon with the most recent occurring between October 2022 and September 2023. The Centre region of Cameroon was the most affected in the country and being at the frontline of the fight against this illness, we conducted this study in order to determine the epidemiological and clinical characteristics as well as the outcome of children who contracted the measles and were hospitalized at the Yaoundé Gynaeco-Obstetric and Pediatric Hospital. Methodology: We conducted a cross-sectional descriptive and prospective study for one year from October 2022 to November 2023 corresponding to the duration of the outbreak. We included all children admitted in the pediatric unit for measles and its complications during this period. Results: In total, 60 children were enrolled. Their caregivers were mostly their mothers who had a mean age of 34.71 ± 9.55 years living in significant precarious conditions for the majority. The median age of children was 16 months (09 - 30 months). Twenty six percent of children (16) were less than 9 months. Girls were predominant (55%). Most children were not up to date with their routine EPI vaccination (80%) and most did not receive the measles and Rubella vaccine (76.67%). Clinical manifestations, included fever, conjunctivitis, and cough. Skin rash and catarrh (98.33% and 86.67% respectively) are the case definition signs of measles. The outcome was unfavorable for 4 children. One had a neurological disorder: coma and three presented with pneumonia and severe respiratory distress (6.67%). Conclusion: Measles is still being a reality and claiming lives in our context, emphasis should be made on immunization coverage and if possible, advocacies should be formulated to decrease the age of measles vaccine administration.展开更多
On-site and real-time non-destructive measurement of elastic constants for materials of a component in a in-service structure is a challenge due to structural complexities,such as ambiguous boundary,variable thickness...On-site and real-time non-destructive measurement of elastic constants for materials of a component in a in-service structure is a challenge due to structural complexities,such as ambiguous boundary,variable thickness,nonuniform material properties.This work develops for the first time a method that uses ultrasound echo groups and artificial neural network(ANN)for reliable on-site real-time identification of material parameters.The use of echo groups allows the use of lower frequencies,and hence more accommodative to structural complexity.To train the ANNs,a numerical model is established that is capable of computing the waveform of ultrasonic echo groups for any given set of material properties of a given structure.The waveform of an ultrasonic echo groups at an interest location on the surface the structure with material parameters varying in a predefined range are then computed using the numerical model.This results in a set of dataset for training the ANN model.Once the ANN is trained,the material parameters can be identified simultaneously using the actual measured echo waveform as input to the ANN.Intensive tests have been conducted both numerically and experimentally to evaluate the effectiveness and accuracy of the currently proposed method.The results show that the maximum identification error of numerical example is less than 2%,and the maximum identification error of experimental test is less than 7%.Compared with currently prevailing methods and equipment,the proposefy the density and thickness,in addition to the elastic constants.Moreover,the reliability and accuracy of inverse prediction is significantly improved.Thus,it has broad applications and enables real-time field measurements,which has not been fulfilled by any other available methods or equipment.展开更多
Since 2016,community group buying has grown significantly in China,largely driven by its efficient logistics,supply chains,low prices,and convenience.This model has been further popularized during the COVID-19 pandemi...Since 2016,community group buying has grown significantly in China,largely driven by its efficient logistics,supply chains,low prices,and convenience.This model has been further popularized during the COVID-19 pandemic due to its effectiveness in meeting daily needs while minimizing human-to-human contact.A key component of this business model is the“group leaders”-influential individuals within a community responsible for managing group buying activities,which include order collection,supplier liaison,and goods distribution.Their primary task is to form and sustain a reliable community group buying consortium,a task that demands excellent organizational and interpersonal skills.This paper examines this phenomenon using the lens of the differential mode of association,a theoretical model explaining interpersonal relationships in traditional Chinese society.The research indicates that group leaders,through regular interaction with consumers,are able to alter their social network position,increase their influence,understand consumer needs,provide satisfying services,and enhance trust,thereby transforming consumers into loyal group buying participants.This transformation not only brings stability to group buying activities but also reinforces the community influence of group leaders,thus fostering the growth of community group buying.展开更多
To prepare a highly efficient NiMo/Al_(2)O_(3) hydrodesulfurization catalyst,the combined effects of specific organic functional groups and alumina surface characteristics were investigated.First,the correlation betwe...To prepare a highly efficient NiMo/Al_(2)O_(3) hydrodesulfurization catalyst,the combined effects of specific organic functional groups and alumina surface characteristics were investigated.First,the correlation between the surface characteristics of four different alumina and the existing Mo species states was established.It was found that the Mo equilibrium adsorption capacity can be used as a specific descriptor to quantitatively evaluate the changes in surface characteristics of different alumina.A lower Mo equilibrium adsorption capacity for alumina means weaker metal-support interaction and the loaded Mo species are easier to transform into MoS2.However,the Mo-O-Al bonds still exist at the metal-support interface.The introduction of cationic surfactant hecadecyl trimethyl ammonium bromide(CTAB)can further improve Mo species dispersion through electrostatic attraction with Mo anions and interaction of its alkyl chain with the alumina surface;meanwhile,the introduction of ethylenediamine tetraacetic acid(EDTA)can complex with Ni ions to enhance the Ni-promoting effect on Mo.Therefore,the NiMo catalyst designed using alumina with lower Mo equilibrium adsorption capacity and the simultaneous addition of EDTA and CTAB exhibits the highest hydrodesulfurization activity for 4,6-dimethyl dibenzothiophene because of its proper metal-support interaction and more well-dispersed Ni-Mo-S active phases.展开更多
MXenes are a novel family of two-dimensional(2D)materials that are fast gaining popularity due to their versatile characteristics.The surfaces of these materials are often functionalized by negatively charged terminal...MXenes are a novel family of two-dimensional(2D)materials that are fast gaining popularity due to their versatile characteristics.The surfaces of these materials are often functionalized by negatively charged terminal groups,such as=O,OH,and F during their synthesis,and it has been hypothesized that regulating the surface terminators enables to control the material characteristics.However,there is still a large gap between computational and experimental investigations regarding comprehending the surface functional groups.Surfaces with mixed terminations are consistently synthesized in experiments,although pure terminated surfaces are predicted by computational research.Here we summarized the nature of chemical bonding in transition metal carbide materials(MXenes)by1H and19F nuclear magnetic resonance(NMR),Raman,X-ray absorption near edge structure(XANES),extended X-ray absorption fine structure(EXAFS),ultraviolet photoelectron spectroscopy(UPS),X-ray photoelectron spectroscopy(XPS)/scanning transmission electron microscopy(STEM),and thermogravimetric analysis-mass spectrometry(TGA-MS)characterizations.Previous literature reveals that=O,–OH,–F,and–Cl are typical MXene surface terminators.However,recent comparative investigations on the valence band intensity distribution in MXenes reveal that the–OH cannot be considered an intrinsic termination species in MXenes.The surface terminals(=O,–OH,–F,and–Cl)of several MXenes,particularly V2CTxand Ti3C2Tx,will be identified and quantified here.We have also discussed different etching approaches for the synthesis of MXene,the dependence of MXene conductivity on MXene terminating groups,and the emission of various gaseous products that evolved during its chemical transformations.This paper provides significance,especially in the field of energy conversion and storage materials,where the intercalation process is crucial.展开更多
BACKGROUND Colorectal cancer(CRC)remains a relevant public health problem.Current research suggests that racial,economic and geographic disparities impact access.Despite the expansion of Medicaid eligibility as a key ...BACKGROUND Colorectal cancer(CRC)remains a relevant public health problem.Current research suggests that racial,economic and geographic disparities impact access.Despite the expansion of Medicaid eligibility as a key component of the Affordable Care Act(ACA),there is a dearth of information on the utilization of newly gained access to CRC screening by low-income individuals.This study investigates the impact of the ACA’s Medicaid expansion on utilization of the various CRC screening modalities by low-income participants.Our working hypothesis is that Medicaid expansion will increase access and utilization of CRC screening by low-income participants.AIM To investigate the impact of the Affordable Care Act and in particular the effect of Medicaid expansion on access and utilization of CRC screening modalities by Medicaid state expansion status across the United States.METHODS This was a quasi-experimental study design using data from the Behavioral Risk Factor Surveillance System,a large health system survey for participants across the United States and with over 2.8 million responses.The period of the study was from 2011 to 2016 which was dichotomized as pre-ACA Medicaid expansion(2011-2013)and post-ACA Medicaid expansion(2014-2016).The change in utilization of access to CRC screening strategies between the expansion periods were analyzed as the dependent variables.Secondary analyses included stratification of the access by ethnicity/race,income,and education status.RESULTS A greater increase in utilization of access to CRC screening was observed in Medicaid expansion states than in nonexpansion states[+2.9%;95%confidence interval(95%CI):2.12,3.69].Low-income participants showed a+4.02%(95%CI:2.96,5.07)change between the expansion periods compared with higher income groups+3.19%(1.70,4.67).Non-Hispanic Whites and Hispanics[+3.01%(95%CI:2.16,3.85)vs+5.51%(95%CI:2.81,8.20)]showed a statistically significant increase in utilization of access but not in Non-Hispanic Blacks,or Multiracial.There was an increase in utilization across all educational levels.This was significant among those who reported having a high school graduate degree or more+4.26%(95%CI:3.16,5.35)compared to some high school or less+1.59%(95%CI:-1.37,4.55).CONCLUSION Medicaid expansion under the Affordable Care Act led to an overall increase in self-reported use of CRC screening tests by adults aged 50-64 years in the United States.This finding was consistent across all low-income populations,but not all races or levels of education.展开更多
In the course of organic synthesis, particularly for multi-step synthesis or natural product total synthesis, the selection of appropriate protective groups for the intended functionality is crucial in order to achiev...In the course of organic synthesis, particularly for multi-step synthesis or natural product total synthesis, the selection of appropriate protective groups for the intended functionality is crucial in order to achieve chemoselective synthetic goals. The development of many useful protective groups has been reported based on the functionality of the anilino group. Herein, we discuss our study of various protective groups and the processes we used to establish compatibility with anilino functionality via the implementation of Oxone-mediated oxidative esterification in methanol. The results and the details of our experiments are reported herein.展开更多
Zooplankton are important linkages in the food web and can respond nonlinearly to environmental changes.Marine organisms thrive from spring to summer.Thus,it is crucial to understand how ecological functions of zoopla...Zooplankton are important linkages in the food web and can respond nonlinearly to environmental changes.Marine organisms thrive from spring to summer.Thus,it is crucial to understand how ecological functions of zooplankton communities may shift under seasonal environmental changes during this period.Samples were collected from May to August(May,June-Ⅰ,June-Ⅱ,July-Ⅰ,July-Ⅱ,and August)in 2018 in Haizhou Bay,Jiangsu,East China for zooplankton and environmental variables.Crustaceans accounted for 75 out of 134 zooplankton taxa and 91.8%of total zooplankton abundance.The average abundance of crustacean varied between 2824.6±635.4 inds./m3 in July-Ⅱand 6502.7±1008.8 inds./m3 in June-Ⅱ.Multivariate analyses results showed that the dissimilarity of community increased gradually in the time series.Body length,feeding type,trophic group,and reproduction mode were used to investigate crustacean community functions.Trait-based functional groups contained species with similar ecological roles.Functional diversity fused the differences of species and trait.The proportion of large-sized species(2-5 mm)decreased with the increasing proportion of medium-sized species(1-2 mm).The proportion of current feeders increased with the drop in the proportion of mixed feeders.Parthenogenesis species increased with decreasing free spawners,and omnivores-carnivores increased with decreasing omnivoresherbivores.Generalized additive models suggested that temperature was the main driver of variations in crustacean zooplankton function.Seven identified functional groups varied with increasing temperature.Omnivorous-herbivorous copepods declined(90.0%-68.0%),whereas the parthenogenetic cladocerans increased(0-24.1%).The small egg-brooding ambush copepods fluctuated(6.5%-9.3%)with increasing water temperature.The other functional groups changed slightly.Functional diversity also varied according to temperature changes.The community structure and ecological function of crustacean zooplankton community showed gradual changes with increasing temperature from spring to summer.展开更多
In our paper Simplicial K(G, 1)’s we constructed a sub-complex of the nerve of a group G determined by a partial group structure, and we proved, under a generalized associativity condition called regularity, that the...In our paper Simplicial K(G, 1)’s we constructed a sub-complex of the nerve of a group G determined by a partial group structure, and we proved, under a generalized associativity condition called regularity, that the sub-complex realizes as a K(G, 1). This type of sub-complex appears naturally in several topological and algebraic contexts. In this note we prove that regularity of a partial group implies that the Kan extension condition is satisfied on its nerve in dimensions greater than one, and in dimension one a weaker version of the extension condition holds.展开更多
Water pollution regarding dyes and heavy metal ions is crucial facing the world.How to effectively separate these contaminants from water has been a key issue.Graphene oxide(GO)promises the greenwater world as a long-...Water pollution regarding dyes and heavy metal ions is crucial facing the world.How to effectively separate these contaminants from water has been a key issue.Graphene oxide(GO)promises the greenwater world as a long-lasting spotlight adsorbent material and therefore,harnessing GO has been the research hotspot for over a decade.The state of GO as well as its surface functional groups plays an important role in adsorption.And the way of preparation and structural modification matters to the performance of GO.In this review,the significance of the state of existence of stock GO and surface functional groups is explored in terms of preparation,structural modification,and adsorption.Besides,various adsorbates for GO adsorption are also involved,the discussion of which is rarely established elsewhere.展开更多
With the penetration of the Internet, virtual groups have become more and more popular. The reliability and accuracy of interpersonal perception in the virtual environment is an intriguing issue. Using the Social rela...With the penetration of the Internet, virtual groups have become more and more popular. The reliability and accuracy of interpersonal perception in the virtual environment is an intriguing issue. Using the Social relations model (SRM) [1], this paper investigates interpersonal perception in virtual groups from a multilevel perspective. In particular, it examines the following three areas: homophily, identification, and individual attraction, and explores how much of these directional and dyadic relational evaluations can be attributed to the effect of the actor, the partner, and the relationship.展开更多
American Sign Language(ASL)images can be used as a communication tool by determining numbers and letters using the shape of the fingers.Particularly,ASL can have an key role in communication for hearing-impaired perso...American Sign Language(ASL)images can be used as a communication tool by determining numbers and letters using the shape of the fingers.Particularly,ASL can have an key role in communication for hearing-impaired persons and conveying information to other persons,because sign language is their only channel of expression.Representative ASL recognition methods primarily adopt images,sensors,and pose-based recognition techniques,and employ various gestures together with hand-shapes.This study briefly reviews these attempts at ASL recognition and provides an improved ASL classification model that attempts to develop a deep learning method with meta-layers.In the proposed model,the collected ASL images were clustered based on similarities in shape,and clustered group classification was first performed,followed by reclassification within the group.The experiments were conducted with various groups using different learning layers to improve the accuracy of individual image recognition.After selecting the optimized group,we proposed a meta-layered learning model with the highest recognition rate using a deep learning method of image processing.The proposed model exhibited an improved performance compared with the general classification model.展开更多
Fine roots play key roles in belowground C cycling in terrestrial ecosystems.Based on their distinct functions,fi ne roots are either absorptive fi ne roots(AFRs)or transport fi ne roots(TFRs).However,the function-bas...Fine roots play key roles in belowground C cycling in terrestrial ecosystems.Based on their distinct functions,fi ne roots are either absorptive fi ne roots(AFRs)or transport fi ne roots(TFRs).However,the function-based fi ne root dynamics of trees and their responses to forest stand properties remain unclear.Here,we studied the dynamics of AFRs and TFRs and their responses to stand conditions and root density in a subtropical montane mixed forest based on a 2-a root window experiment.Mean(±SE)annual production,mortality,and turnover rate of AFRs were 7.87±0.17 m m^(−2)a^(−1),8.13±0.20 m m^(−2)a^(−1)and 2.96±0.24 a^(−1),respectively,compared with 7.09±0.17 m m^(−2)a^(−1),4.59±0.17 m m^(−2)a^(−1),and 2.01±0.22 a^(−1),respectively,for TFRs.The production and mortality of fi ne roots were signifi cantly higher in high root-density sites than in low-root density sites,whereas the turnover of fi ne roots was faster in the low root-density sites.Furthermore,root density had a larger positive eff ect than other environmental factors on TFR production but had no obvious impact on AFR production.Tree species diversity had an apparent positive eff ect on AFR production and was the crucial driver of AFR production,probably due to a complementary eff ect,but had no evident impact on TFR.Both tree density and tree species diversity were positively correlated with the mortality of AFRs and negatively related to the turnover of TFRs,suggesting that higher root density caused stronger competition for rooting space and that plants tend to reduce maintenance costs by decreasing TFR turnover.These fi ndings illustrated the importance of root functional groups in understanding root dynamics and their responses to changes in environmental conditions.展开更多
In this research,two shake table experiments were conducted to study the effects of non-liquefiable crust layer and superstructure mass on the responses of two sets of 22 pile groups to liquefactioninduced lateral spr...In this research,two shake table experiments were conducted to study the effects of non-liquefiable crust layer and superstructure mass on the responses of two sets of 22 pile groups to liquefactioninduced lateral spreading.In this regard,an inclined base layer overlain by a very loose liquefiable layer was constructed in both models;while only in one model,a non-liquefiable crust layer was built.A lumped mass,being representative of a superstructure,was attached to the cap of one pile group in both models.The models were fully instrumented with various sensors,including acceleration,displacement,and pore water pressure transducers.Also,the piles were instrumented with pair strain gauges to measure pure bending moments induced by cyclic and monotonic loadings associated with ground shaking and lateral spreading,respectively.The results showed that the existence of the non-liquefiable crust layer increases both the maximum and residual soil displacements at the free field and also the maximum bending moments in the piles.The results of the experiments indicated that the crust layer induces a high kinematic lateral soil pressure and force on the piles which are not present in the crustless case.The crust layer increases the pile cap displacement before liquefaction,albeit decreases it after liquefaction,due to the elastic rebound of the piles in the liquefiable layer.The crust layer postpones both liquefaction triggering and dissipation of excess pore water pressure.The existence of the superstructure mass on the pile caps decreases the acceleration amplitude of the pile caps,while increases their maximum displacement.展开更多
Attribute-based encryption with keyword search(ABEKS)is a novel cryptographic paradigm that can be used to implementfine-grained access control and retrieve ciphertexts without disclosing the sensitive information.It i...Attribute-based encryption with keyword search(ABEKS)is a novel cryptographic paradigm that can be used to implementfine-grained access control and retrieve ciphertexts without disclosing the sensitive information.It is a perfect combination of attribute-based encryption(ABE)and public key encryption with keyword search(PEKS).Nevertheless,most of the existing ABEKS schemes have limited search capabilities and only support single or simple conjunctive keyword search.Due to the weak search capability and inaccurate search results,it is difficult to apply these schemes to practical applications.In this paper,an effi-cient expressive ABEKS(EABEKS)scheme supporting unbounded keyword uni-verse over prime-order groups is designed,which supplies the expressive keyword search function supporting the logical connectives of“AND”and“OR”.The proposed scheme not only leads to low computation and communica-tion costs,but also supports unbounded keyword universe.In the standard model,the scheme is proven to be secure under the chosen keyword attack and the cho-sen plaintext attack.The comparison analysis and experimental results show that it has better performance than the existing EABEKS schemes in the storage,com-putation and communication costs.展开更多
The interfacial defects and energy barrier are main reasons for interfacial nonradiative recombination.In addition,poor perovskite crystallization and incomplete conversion of PbI_(2) to perovskite restrict further en...The interfacial defects and energy barrier are main reasons for interfacial nonradiative recombination.In addition,poor perovskite crystallization and incomplete conversion of PbI_(2) to perovskite restrict further enhancement of the photovoltaic performance of the devices using sequential deposition.Herein,a buried interface stabilization strategy that relies on the synergy of fluorine(F)and sulfonyl(S=O)functional groups is proposed.A series of potassium salts containing halide and non-halogen anions are employed to modify SnO_(2)/perovskite buried interface.Multiple chemical bonds including hydrogen bond,coordination bond and ionic bond are realized,which strengthens interfacial contact and defect passivation effect.The chemical interaction between modification molecules and perovskite along with SnO_(2) heightens incessantly as the number of S=O and F augments.The chemical interaction strength between modifiers and perovskite as well as SnO_(2) gradually increases with the increase in the number of S=O and F.The defect passivation effect is positively correlated with the chemical interaction strength.The crystallization kinetics is regulated through the compromise between chemical interaction strength and wettability of substrates.Compared with Cl−,all non-halogen anions perform better in crystallization optimization,energy band regulation and defect passivation.The device with potassium bis(fluorosulfonyl)imide achieves a tempting efficiency of 24.17%.展开更多
Some dynamical properties were discussed for additive cellular automata(CA)over finite abelian groups.These properties include surjection,ergodicity,sensitivity to initial conditions and positive expansivity.Some nece...Some dynamical properties were discussed for additive cellular automata(CA)over finite abelian groups.These properties include surjection,ergodicity,sensitivity to initial conditions and positive expansivity.Some necessary and sufficient conditions of determining ergodicity and sensitivity of the above additive CA were presented,respectively.A necessary condition for the positive expansivity of the above additive CA was given.The positive expansivity was proved to be preserved under the shift mappings for the general CA.The discussion was mainly based on the structure theorem of the finite abelian groups and the matrix associated with the global rule of the additive CA over the finite abelian p-groups.展开更多
文摘With the completion of the strategic vision of building a moderately prosperous society in an all-round way in 2020,China’s economic development has entered a new normal.The concept of innovative,coordinated,green,open and shared development will lead China’s economic progress and development.However,the development of urban and rural areas and regions in China is still not coordinated,and the sudden COVID-19 outbreak has caused a serious impact on urban low-income groups.Due to the characteristics of poor employment stability,low income and single source,as well as greater family pressure of urban low-income groups,the author focuses on the influencing factors of their feelings of happiness.This paper assumes that the satisfaction degree of residents’needs is positively correlated with residents’feelings of happiness.Based on Maslow’s hierarchy of needs theory,this paper analyzes the factors that may affect the happiness of urban low-income groups in five levels,and explores the special needs and difficulties of urban low-income groups in the context of the epidemic.So as to find ways to improve the happiness of urban low-income people to provide reference.
基金supported by the National Natural Science Foundation of China(22172090,21790051)the National Key Research and Development Project of China(2022YFA1204500,2022YFA1204501)+2 种基金the Natural Science Foundation of Shan-dong Province(ZR2021MB015)the Open Funds of the State Key Laboratory of Electroanalytical Chemistry(SKLEAC202202)the Young Scholars Program of Shandong University。
文摘Tuning the coordination atoms of central metal is an effective means to improve the electrocatalytic activity of atomic catalysts.Herein,iridium(Ir) is proposed to be asymmetrically anchored by sp-N and pyridinic N of hydrogen-substituted graphdiyne(HsGDY),and coordinated with OH as an Ir atomic catalyst(Ir_(1)-N-HsGDY).The electron structures,especially the d-band center of Ir atom,are optimized by these specific coordination atoms.Thus,the as-synthesized Ir_(1)-N-HsGDY exhibits excellent electrocatalytic performances for oxygen reduction and hydrogen evolution reactions in both acidic and alkaline media.Benefiting from the unique structure of HsGDY,IrN_(2)(OH)_(3) has been developed and demonstrated to act as the active site in these electrochemical reactions.All those indicate the fresh role of the sp-N in graphdiyne in producing a new anchor way and contributing to promote the electrocatalytic activity,showing a new strategy to design novel electrochemical catalysts.
文摘Introduction: Measles remains a worrying health problem in sub-Saharan African countries. There have been measles outbreaks in Cameroon with the most recent occurring between October 2022 and September 2023. The Centre region of Cameroon was the most affected in the country and being at the frontline of the fight against this illness, we conducted this study in order to determine the epidemiological and clinical characteristics as well as the outcome of children who contracted the measles and were hospitalized at the Yaoundé Gynaeco-Obstetric and Pediatric Hospital. Methodology: We conducted a cross-sectional descriptive and prospective study for one year from October 2022 to November 2023 corresponding to the duration of the outbreak. We included all children admitted in the pediatric unit for measles and its complications during this period. Results: In total, 60 children were enrolled. Their caregivers were mostly their mothers who had a mean age of 34.71 ± 9.55 years living in significant precarious conditions for the majority. The median age of children was 16 months (09 - 30 months). Twenty six percent of children (16) were less than 9 months. Girls were predominant (55%). Most children were not up to date with their routine EPI vaccination (80%) and most did not receive the measles and Rubella vaccine (76.67%). Clinical manifestations, included fever, conjunctivitis, and cough. Skin rash and catarrh (98.33% and 86.67% respectively) are the case definition signs of measles. The outcome was unfavorable for 4 children. One had a neurological disorder: coma and three presented with pneumonia and severe respiratory distress (6.67%). Conclusion: Measles is still being a reality and claiming lives in our context, emphasis should be made on immunization coverage and if possible, advocacies should be formulated to decrease the age of measles vaccine administration.
基金Supported by National Natural Science Foundation of China(Grant No.51805141)Funds for Creative Research Groups of Hebei Province of China(Grant No.E2020202142)+2 种基金Tianjin Municipal Science and Technology Plan Project of China(Grant No.19ZXZNGX00100)Key R&D Program of Hebei Province of China(Grant No.19227208D)National Key Research and development Program of China(Grant No.2020YFB2009400).
文摘On-site and real-time non-destructive measurement of elastic constants for materials of a component in a in-service structure is a challenge due to structural complexities,such as ambiguous boundary,variable thickness,nonuniform material properties.This work develops for the first time a method that uses ultrasound echo groups and artificial neural network(ANN)for reliable on-site real-time identification of material parameters.The use of echo groups allows the use of lower frequencies,and hence more accommodative to structural complexity.To train the ANNs,a numerical model is established that is capable of computing the waveform of ultrasonic echo groups for any given set of material properties of a given structure.The waveform of an ultrasonic echo groups at an interest location on the surface the structure with material parameters varying in a predefined range are then computed using the numerical model.This results in a set of dataset for training the ANN model.Once the ANN is trained,the material parameters can be identified simultaneously using the actual measured echo waveform as input to the ANN.Intensive tests have been conducted both numerically and experimentally to evaluate the effectiveness and accuracy of the currently proposed method.The results show that the maximum identification error of numerical example is less than 2%,and the maximum identification error of experimental test is less than 7%.Compared with currently prevailing methods and equipment,the proposefy the density and thickness,in addition to the elastic constants.Moreover,the reliability and accuracy of inverse prediction is significantly improved.Thus,it has broad applications and enables real-time field measurements,which has not been fulfilled by any other available methods or equipment.
文摘Since 2016,community group buying has grown significantly in China,largely driven by its efficient logistics,supply chains,low prices,and convenience.This model has been further popularized during the COVID-19 pandemic due to its effectiveness in meeting daily needs while minimizing human-to-human contact.A key component of this business model is the“group leaders”-influential individuals within a community responsible for managing group buying activities,which include order collection,supplier liaison,and goods distribution.Their primary task is to form and sustain a reliable community group buying consortium,a task that demands excellent organizational and interpersonal skills.This paper examines this phenomenon using the lens of the differential mode of association,a theoretical model explaining interpersonal relationships in traditional Chinese society.The research indicates that group leaders,through regular interaction with consumers,are able to alter their social network position,increase their influence,understand consumer needs,provide satisfying services,and enhance trust,thereby transforming consumers into loyal group buying participants.This transformation not only brings stability to group buying activities but also reinforces the community influence of group leaders,thus fostering the growth of community group buying.
基金funding of the National Key Research and Development Plan(Grant 2017YFB0306600)the Project of SINOPEC(NO.117006).
文摘To prepare a highly efficient NiMo/Al_(2)O_(3) hydrodesulfurization catalyst,the combined effects of specific organic functional groups and alumina surface characteristics were investigated.First,the correlation between the surface characteristics of four different alumina and the existing Mo species states was established.It was found that the Mo equilibrium adsorption capacity can be used as a specific descriptor to quantitatively evaluate the changes in surface characteristics of different alumina.A lower Mo equilibrium adsorption capacity for alumina means weaker metal-support interaction and the loaded Mo species are easier to transform into MoS2.However,the Mo-O-Al bonds still exist at the metal-support interface.The introduction of cationic surfactant hecadecyl trimethyl ammonium bromide(CTAB)can further improve Mo species dispersion through electrostatic attraction with Mo anions and interaction of its alkyl chain with the alumina surface;meanwhile,the introduction of ethylenediamine tetraacetic acid(EDTA)can complex with Ni ions to enhance the Ni-promoting effect on Mo.Therefore,the NiMo catalyst designed using alumina with lower Mo equilibrium adsorption capacity and the simultaneous addition of EDTA and CTAB exhibits the highest hydrodesulfurization activity for 4,6-dimethyl dibenzothiophene because of its proper metal-support interaction and more well-dispersed Ni-Mo-S active phases.
基金supported by the National Natural Science Foundation of China(21703147 and U1401248)the support of China Scholarship Council(2018SLJ022487)。
文摘MXenes are a novel family of two-dimensional(2D)materials that are fast gaining popularity due to their versatile characteristics.The surfaces of these materials are often functionalized by negatively charged terminal groups,such as=O,OH,and F during their synthesis,and it has been hypothesized that regulating the surface terminators enables to control the material characteristics.However,there is still a large gap between computational and experimental investigations regarding comprehending the surface functional groups.Surfaces with mixed terminations are consistently synthesized in experiments,although pure terminated surfaces are predicted by computational research.Here we summarized the nature of chemical bonding in transition metal carbide materials(MXenes)by1H and19F nuclear magnetic resonance(NMR),Raman,X-ray absorption near edge structure(XANES),extended X-ray absorption fine structure(EXAFS),ultraviolet photoelectron spectroscopy(UPS),X-ray photoelectron spectroscopy(XPS)/scanning transmission electron microscopy(STEM),and thermogravimetric analysis-mass spectrometry(TGA-MS)characterizations.Previous literature reveals that=O,–OH,–F,and–Cl are typical MXene surface terminators.However,recent comparative investigations on the valence band intensity distribution in MXenes reveal that the–OH cannot be considered an intrinsic termination species in MXenes.The surface terminals(=O,–OH,–F,and–Cl)of several MXenes,particularly V2CTxand Ti3C2Tx,will be identified and quantified here.We have also discussed different etching approaches for the synthesis of MXene,the dependence of MXene conductivity on MXene terminating groups,and the emission of various gaseous products that evolved during its chemical transformations.This paper provides significance,especially in the field of energy conversion and storage materials,where the intercalation process is crucial.
文摘BACKGROUND Colorectal cancer(CRC)remains a relevant public health problem.Current research suggests that racial,economic and geographic disparities impact access.Despite the expansion of Medicaid eligibility as a key component of the Affordable Care Act(ACA),there is a dearth of information on the utilization of newly gained access to CRC screening by low-income individuals.This study investigates the impact of the ACA’s Medicaid expansion on utilization of the various CRC screening modalities by low-income participants.Our working hypothesis is that Medicaid expansion will increase access and utilization of CRC screening by low-income participants.AIM To investigate the impact of the Affordable Care Act and in particular the effect of Medicaid expansion on access and utilization of CRC screening modalities by Medicaid state expansion status across the United States.METHODS This was a quasi-experimental study design using data from the Behavioral Risk Factor Surveillance System,a large health system survey for participants across the United States and with over 2.8 million responses.The period of the study was from 2011 to 2016 which was dichotomized as pre-ACA Medicaid expansion(2011-2013)and post-ACA Medicaid expansion(2014-2016).The change in utilization of access to CRC screening strategies between the expansion periods were analyzed as the dependent variables.Secondary analyses included stratification of the access by ethnicity/race,income,and education status.RESULTS A greater increase in utilization of access to CRC screening was observed in Medicaid expansion states than in nonexpansion states[+2.9%;95%confidence interval(95%CI):2.12,3.69].Low-income participants showed a+4.02%(95%CI:2.96,5.07)change between the expansion periods compared with higher income groups+3.19%(1.70,4.67).Non-Hispanic Whites and Hispanics[+3.01%(95%CI:2.16,3.85)vs+5.51%(95%CI:2.81,8.20)]showed a statistically significant increase in utilization of access but not in Non-Hispanic Blacks,or Multiracial.There was an increase in utilization across all educational levels.This was significant among those who reported having a high school graduate degree or more+4.26%(95%CI:3.16,5.35)compared to some high school or less+1.59%(95%CI:-1.37,4.55).CONCLUSION Medicaid expansion under the Affordable Care Act led to an overall increase in self-reported use of CRC screening tests by adults aged 50-64 years in the United States.This finding was consistent across all low-income populations,but not all races or levels of education.
文摘In the course of organic synthesis, particularly for multi-step synthesis or natural product total synthesis, the selection of appropriate protective groups for the intended functionality is crucial in order to achieve chemoselective synthetic goals. The development of many useful protective groups has been reported based on the functionality of the anilino group. Herein, we discuss our study of various protective groups and the processes we used to establish compatibility with anilino functionality via the implementation of Oxone-mediated oxidative esterification in methanol. The results and the details of our experiments are reported herein.
基金Supported by the National Natural Science Foundation of China(Nos.42076146,41876177,41930534)the Fundamental Research Funds for the Central Universities(No.201822027)。
文摘Zooplankton are important linkages in the food web and can respond nonlinearly to environmental changes.Marine organisms thrive from spring to summer.Thus,it is crucial to understand how ecological functions of zooplankton communities may shift under seasonal environmental changes during this period.Samples were collected from May to August(May,June-Ⅰ,June-Ⅱ,July-Ⅰ,July-Ⅱ,and August)in 2018 in Haizhou Bay,Jiangsu,East China for zooplankton and environmental variables.Crustaceans accounted for 75 out of 134 zooplankton taxa and 91.8%of total zooplankton abundance.The average abundance of crustacean varied between 2824.6±635.4 inds./m3 in July-Ⅱand 6502.7±1008.8 inds./m3 in June-Ⅱ.Multivariate analyses results showed that the dissimilarity of community increased gradually in the time series.Body length,feeding type,trophic group,and reproduction mode were used to investigate crustacean community functions.Trait-based functional groups contained species with similar ecological roles.Functional diversity fused the differences of species and trait.The proportion of large-sized species(2-5 mm)decreased with the increasing proportion of medium-sized species(1-2 mm).The proportion of current feeders increased with the drop in the proportion of mixed feeders.Parthenogenesis species increased with decreasing free spawners,and omnivores-carnivores increased with decreasing omnivoresherbivores.Generalized additive models suggested that temperature was the main driver of variations in crustacean zooplankton function.Seven identified functional groups varied with increasing temperature.Omnivorous-herbivorous copepods declined(90.0%-68.0%),whereas the parthenogenetic cladocerans increased(0-24.1%).The small egg-brooding ambush copepods fluctuated(6.5%-9.3%)with increasing water temperature.The other functional groups changed slightly.Functional diversity also varied according to temperature changes.The community structure and ecological function of crustacean zooplankton community showed gradual changes with increasing temperature from spring to summer.
文摘In our paper Simplicial K(G, 1)’s we constructed a sub-complex of the nerve of a group G determined by a partial group structure, and we proved, under a generalized associativity condition called regularity, that the sub-complex realizes as a K(G, 1). This type of sub-complex appears naturally in several topological and algebraic contexts. In this note we prove that regularity of a partial group implies that the Kan extension condition is satisfied on its nerve in dimensions greater than one, and in dimension one a weaker version of the extension condition holds.
基金supported by the National Natural Science Foundation of China(51902007)。
文摘Water pollution regarding dyes and heavy metal ions is crucial facing the world.How to effectively separate these contaminants from water has been a key issue.Graphene oxide(GO)promises the greenwater world as a long-lasting spotlight adsorbent material and therefore,harnessing GO has been the research hotspot for over a decade.The state of GO as well as its surface functional groups plays an important role in adsorption.And the way of preparation and structural modification matters to the performance of GO.In this review,the significance of the state of existence of stock GO and surface functional groups is explored in terms of preparation,structural modification,and adsorption.Besides,various adsorbates for GO adsorption are also involved,the discussion of which is rarely established elsewhere.
文摘With the penetration of the Internet, virtual groups have become more and more popular. The reliability and accuracy of interpersonal perception in the virtual environment is an intriguing issue. Using the Social relations model (SRM) [1], this paper investigates interpersonal perception in virtual groups from a multilevel perspective. In particular, it examines the following three areas: homophily, identification, and individual attraction, and explores how much of these directional and dyadic relational evaluations can be attributed to the effect of the actor, the partner, and the relationship.
基金This research was supported by the National Research Foundation of Korea(NRF)funded by the Ministry of Science,ICT and Future Planning(NRF-2019R1A2C1084308).
文摘American Sign Language(ASL)images can be used as a communication tool by determining numbers and letters using the shape of the fingers.Particularly,ASL can have an key role in communication for hearing-impaired persons and conveying information to other persons,because sign language is their only channel of expression.Representative ASL recognition methods primarily adopt images,sensors,and pose-based recognition techniques,and employ various gestures together with hand-shapes.This study briefly reviews these attempts at ASL recognition and provides an improved ASL classification model that attempts to develop a deep learning method with meta-layers.In the proposed model,the collected ASL images were clustered based on similarities in shape,and clustered group classification was first performed,followed by reclassification within the group.The experiments were conducted with various groups using different learning layers to improve the accuracy of individual image recognition.After selecting the optimized group,we proposed a meta-layered learning model with the highest recognition rate using a deep learning method of image processing.The proposed model exhibited an improved performance compared with the general classification model.
基金supported by the National Natural Science Foundation of China(Grant No.3217159931870465).
文摘Fine roots play key roles in belowground C cycling in terrestrial ecosystems.Based on their distinct functions,fi ne roots are either absorptive fi ne roots(AFRs)or transport fi ne roots(TFRs).However,the function-based fi ne root dynamics of trees and their responses to forest stand properties remain unclear.Here,we studied the dynamics of AFRs and TFRs and their responses to stand conditions and root density in a subtropical montane mixed forest based on a 2-a root window experiment.Mean(±SE)annual production,mortality,and turnover rate of AFRs were 7.87±0.17 m m^(−2)a^(−1),8.13±0.20 m m^(−2)a^(−1)and 2.96±0.24 a^(−1),respectively,compared with 7.09±0.17 m m^(−2)a^(−1),4.59±0.17 m m^(−2)a^(−1),and 2.01±0.22 a^(−1),respectively,for TFRs.The production and mortality of fi ne roots were signifi cantly higher in high root-density sites than in low-root density sites,whereas the turnover of fi ne roots was faster in the low root-density sites.Furthermore,root density had a larger positive eff ect than other environmental factors on TFR production but had no obvious impact on AFR production.Tree species diversity had an apparent positive eff ect on AFR production and was the crucial driver of AFR production,probably due to a complementary eff ect,but had no evident impact on TFR.Both tree density and tree species diversity were positively correlated with the mortality of AFRs and negatively related to the turnover of TFRs,suggesting that higher root density caused stronger competition for rooting space and that plants tend to reduce maintenance costs by decreasing TFR turnover.These fi ndings illustrated the importance of root functional groups in understanding root dynamics and their responses to changes in environmental conditions.
基金support by the Construction and Development of Transportation Infrastructures Company affiliated with the Ministry of Roads and Urban Development of Iran and partial financial support granted by the Research Deputy of the Sharif University of Technology are acknowledged.
文摘In this research,two shake table experiments were conducted to study the effects of non-liquefiable crust layer and superstructure mass on the responses of two sets of 22 pile groups to liquefactioninduced lateral spreading.In this regard,an inclined base layer overlain by a very loose liquefiable layer was constructed in both models;while only in one model,a non-liquefiable crust layer was built.A lumped mass,being representative of a superstructure,was attached to the cap of one pile group in both models.The models were fully instrumented with various sensors,including acceleration,displacement,and pore water pressure transducers.Also,the piles were instrumented with pair strain gauges to measure pure bending moments induced by cyclic and monotonic loadings associated with ground shaking and lateral spreading,respectively.The results showed that the existence of the non-liquefiable crust layer increases both the maximum and residual soil displacements at the free field and also the maximum bending moments in the piles.The results of the experiments indicated that the crust layer induces a high kinematic lateral soil pressure and force on the piles which are not present in the crustless case.The crust layer increases the pile cap displacement before liquefaction,albeit decreases it after liquefaction,due to the elastic rebound of the piles in the liquefiable layer.The crust layer postpones both liquefaction triggering and dissipation of excess pore water pressure.The existence of the superstructure mass on the pile caps decreases the acceleration amplitude of the pile caps,while increases their maximum displacement.
基金supported in part by the National Natural Science Foundation of China under Grant No.61772009the Natural Science Foundation of Jiangsu Province under Grant No.BK20181304.
文摘Attribute-based encryption with keyword search(ABEKS)is a novel cryptographic paradigm that can be used to implementfine-grained access control and retrieve ciphertexts without disclosing the sensitive information.It is a perfect combination of attribute-based encryption(ABE)and public key encryption with keyword search(PEKS).Nevertheless,most of the existing ABEKS schemes have limited search capabilities and only support single or simple conjunctive keyword search.Due to the weak search capability and inaccurate search results,it is difficult to apply these schemes to practical applications.In this paper,an effi-cient expressive ABEKS(EABEKS)scheme supporting unbounded keyword uni-verse over prime-order groups is designed,which supplies the expressive keyword search function supporting the logical connectives of“AND”and“OR”.The proposed scheme not only leads to low computation and communica-tion costs,but also supports unbounded keyword universe.In the standard model,the scheme is proven to be secure under the chosen keyword attack and the cho-sen plaintext attack.The comparison analysis and experimental results show that it has better performance than the existing EABEKS schemes in the storage,com-putation and communication costs.
基金supported by the Defense Industrial Technology Development Program(JCKY2017110C0654)National Natural Science Foundation of China(11974063,61904023,62274018)+1 种基金Chongqing Special Postdoctoral Science Foundation(cstc2019jcyj-bsh0026)Fundamental Research Funds for the Central Universities(2021CDJQY-022).
文摘The interfacial defects and energy barrier are main reasons for interfacial nonradiative recombination.In addition,poor perovskite crystallization and incomplete conversion of PbI_(2) to perovskite restrict further enhancement of the photovoltaic performance of the devices using sequential deposition.Herein,a buried interface stabilization strategy that relies on the synergy of fluorine(F)and sulfonyl(S=O)functional groups is proposed.A series of potassium salts containing halide and non-halogen anions are employed to modify SnO_(2)/perovskite buried interface.Multiple chemical bonds including hydrogen bond,coordination bond and ionic bond are realized,which strengthens interfacial contact and defect passivation effect.The chemical interaction between modification molecules and perovskite along with SnO_(2) heightens incessantly as the number of S=O and F augments.The chemical interaction strength between modifiers and perovskite as well as SnO_(2) gradually increases with the increase in the number of S=O and F.The defect passivation effect is positively correlated with the chemical interaction strength.The crystallization kinetics is regulated through the compromise between chemical interaction strength and wettability of substrates.Compared with Cl−,all non-halogen anions perform better in crystallization optimization,energy band regulation and defect passivation.The device with potassium bis(fluorosulfonyl)imide achieves a tempting efficiency of 24.17%.
基金National Natural Science Foundation of China(No.11671258)。
文摘Some dynamical properties were discussed for additive cellular automata(CA)over finite abelian groups.These properties include surjection,ergodicity,sensitivity to initial conditions and positive expansivity.Some necessary and sufficient conditions of determining ergodicity and sensitivity of the above additive CA were presented,respectively.A necessary condition for the positive expansivity of the above additive CA was given.The positive expansivity was proved to be preserved under the shift mappings for the general CA.The discussion was mainly based on the structure theorem of the finite abelian groups and the matrix associated with the global rule of the additive CA over the finite abelian p-groups.