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Exfoliation of two-dimensional (2D) nanosheets from three-dimensional (3D) non-layered, non-van der Waals crystals represents an emerging strategy for materials engineering that could significantly increase the library of 2D materials. Yet, the exfoliation mechanism in which nanosheets are derived from crystals that are not intrinsically layered remains unclear. Here, we show that planar defects in the starting 3D boron material promote the exfoliation of 2D boron sheets-by combining liquid-phase exfoliation, aberration-corrected scanning transmission electron microscopy, Raman spectroscopy, and density functional theory calculations. We demonstrate that 2D boron nanosheets consist of a planar arrangement of icosahedral sub-units cleaved along the {001} planes of ß-rhombohedral boron. Correspondingly, intrinsic stacking faults in 3D boron form parallel layers of faulted planes in the same orientation as the exfoliated nanosheets, reducing the {001} cleavage energy. Planar defects represent a potential engineerable pathway for exfoliating 2D sheets from 3D boron and, more broadly, the other covalently bonded materials.
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Capsaicin, a chemical compound present in chili peppers, is widely acknowledged as the main contributor to the spicy and hot sensations encountered during consumption. Elevated levels of capsaicin can result in meals being excessively spicy, potentially leading to health issues, such as skin burning, irritation, increased heart rate and circulation, and discomfort in the gastrointestinal system and even inducing nausea or diarrhea. The level of spiciness that individuals can tolerate may vary, so what may be considered incredibly hot for one person could be mild for another. To ensure food safety, human healthcare, regulatory compliance, and quality control in spicy food products, capsaicin levels must be measured. For these purposes, a reliable and stable sensor is required to quantify the capsaicin level. To leverage the effect of zinc oxide (ZnO), herein, we demonstrated the one-step fabrication process of an electronic tongue (E-Tongue) based on an electrochemical biosensor for the determination of capsaicin. ZnO was electrodeposited on the indium tin oxide (ITO) surface. The biosensor demonstrated the two notable linear ranges from 0.01 to 50 µM and from 50 to 500 µM with a limit of detection (LOD) of 2.1 nM. The present study also included the analysis of real samples, such as green chilis, red chili powder, and dried red chilis, to evaluate their spiciness levels. Furthermore, the E-Tongue exhibited notable degrees of sensitivity, selectivity, and long-term stability for a duration of more than a month. The development of an E-Tongue for capsaicin real-time monitoring as a point-of-care (POC) device has the potential to impact various industries and improve safety, product quality, and healthcare outcomes.
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Capsaicina , Óxido de Zinco , Humanos , Capsaicina/química , Óxido de Zinco/química , Nariz Eletrônico , Compostos de EstanhoRESUMO
Promoting conservation on rented farmland is a challenge for stakeholders working with non-operating landowners (NOLs) and tenant farmers (operators). We conducted an online survey to identify stakeholders who engage with NOLs, and understand how their positioning as 'intermediaries' could be leveraged to help bridge the NOL-operator communication gap. A majority of identified stakeholders/intermediaries worked in government agencies, university extension, law firms, or farm management companies. Intermediaries believed that NOLs trusted them for several conservation activities, however, they believed that NOLs were more influenced by operators than by intermediaries. The message that engaging in conservation can help preserve the farm for future generation was perceived to be influential in motivating NOLs. Our findings suggest the need for a holistic approach to engage NOLs by accounting for trust in and influence of intermediaries and operators, and the salience of conservation messages and messaging when promoting conservation behaviors on rented farmlands.
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Conservação dos Recursos Naturais , Fazendeiros , Humanos , Fazendas , Inquéritos e Questionários , Comunicação , AgriculturaRESUMO
Increased funding and resources have become available in recent years for agricultural producers to plant cover crops to improve soil health and prevent nutrient loss and erosion; however, cover crop adoption remains relatively low and has been uneven across different Midwestern counties. This study employed a controlled comparison method to investigate the social factors affecting cover crop adoption in Iowa, Illinois, and Indiana. In each state, the authors compared pairs of neighboring counties, where one county was a relatively higher adopter and the other was a lower adopter of cover crops, while controlling for variations in climate conditions. Results show that there were multiple factors explaining the difference in cover crop adoption among county pairs. Social factors included attitudes toward cover crops; conservation agency influence; presence of cover crop experts, advocates, and/or entrepreneurs; and collaboration between agencies and the private sector. Other important factors included topography, cattle raising, organic production, and local incentive-based programs. Among these, collaborations between agencies and the private sector played the most important role in explaining why some counties had higher rates of cover crop adoption compared to their neighbors.
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Fatores Sociais , Solo , Animais , Bovinos , Agricultura/métodos , Produtos Agrícolas , ClimaRESUMO
Conservation practices (CPs) are integral to maintaining the long-term viability of agro-ecological systems. Because farming systems and farmers' values and attitudes are heterogeneous, factors that consistently predict conservation behaviors remain elusive. Moreover, heterogeneity is present among studies regarding the type of CPs examined, and whether behavioral intentions or actual behaviors were measured. This study considers the characteristics of each CP, and whether a given study measured behavioral intention or actual behavior, to better understand farmers' adoption of CPs. We reviewed and analyzed 35 years (1982-2017) of quantitative conservation adoption literature in the United States. We categorized CPs based on their primary purpose, the type of benefit they provide, and whether they are operational or structural. We also examined the following five CPs: conservation tillage, buffers or borders, soil testing, grassed waterways, and cover crops. In our behavioral intention and actual behavior analysis, we found that attitudinal factors predicted both conservation intention and action (actual behavior), whereas current or previous use of practices only influenced actions, not stated conservation intentions. In our analysis focusing on CP characteristics, we found that having specific knowledge about and positive attitudes toward the CP, adoption of other CPs, seeking and using information, larger farm size, and vulnerable land predicted actual adoption across nearly all CP categorizations. Nuances emerge when comparing predictors of CPs that share a particular characteristic. For example, we found farm characteristics to be comparatively more important in predicting adoption of soil management CPs than nutrient and livestock management CPs, and farmers' stewardship identity to be more important for permanent practices than operational practices.
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Agricultura , Intenção , Estados Unidos , Humanos , Inquéritos e Questionários , Fazendeiros , SoloRESUMO
Quantum flatland i.e., the family of two dimensional (2D) quantum materials has become increscent and has already encompassed elemental atomic sheets (Xenes), 2D transition metal dichalcogenides (TMDCs), 2D metal nitrides/carbides/carbonitrides (MXenes), 2D metal oxides, 2D metal phosphides, 2D metal halides, 2D mixed oxides, etc. and still new members are being explored. Owing to the occurrence of various structural phases of each 2D material and each exhibiting a unique electronic structure; bestows distinct physical and chemical properties. In the early years, world record electronic mobility and fractional quantum Hall effect of graphene attracted attention. Thanks to excellent electronic mobility, and extreme sensitivity of their electronic structures towards the adjacent environment, 2D materials have been employed as various ultrafast precision sensors such as gas/fire/light/strain sensors and in trace-level molecular detectors and disease diagnosis. 2D materials, their doped versions, and their hetero layers and hybrids have been successfully employed in electronic/photonic/optoelectronic/spintronic and straintronic chips. In recent times, quantum behavior such as the existence of a superconducting phase in moiré hetero layers, the feasibility of hyperbolic photonic metamaterials, mechanical metamaterials with negative Poisson ratio, and potential usage in second/third harmonic generation and electromagnetic shields, etc. have raised the expectations further. High surface area, excellent young's moduli, and anchoring/coupling capability bolster hopes for their usage as nanofillers in polymers, glass, and soft metals. Even though lab-scale demonstrations have been showcased, large-scale applications such as solar cells, LEDs, flat panel displays, hybrid energy storage, catalysis (including water splitting and CO2 reduction), etc. will catch up. While new members of the flatland family will be invented, new methods of large-scale synthesis of defect-free crystals will be explored and novel applications will emerge, it is expected. Achieving a high level of in-plane doping in 2D materials without adding defects is a challenge to work on. Development of understanding of inter-layer coupling and its effects on electron injection/excited state electron transfer at the 2D-2D interfaces will lead to future generation heterolayer devices and sensors.
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Borophene, the lightest among all Xenes, possesses extreme electronic mobility along with high carrier density and high Young's modulus. To accomplish device-quality borophene, novel approaches of realization of monolayers need to be urgently explored. In this work, micromechanical exfoliation is discovered to result in mono- and few-layered borophene of device quality. Borophene sheets are successfully fabricated down to monolayer thickness. Distinct crystallographic phases of borophene viz. XRD study reveals crystallographic phase transition from rhombohedral to several other eigen phases of borophene. The role of the destination substrates is held crucial in determining the final phase of the transferred sheet. The exfoliation energy is calculated by density functional theory. Molecular dynamics simulations are used to simulate the exfoliation process. Heterolayers of borophene, with black phosphorene (BP) or with molybdenum disulfide (MoS2 ) atomic sheets, are found to result in photoexcited coupling quantum states. Gold-coated borophene bestows promising anchoring capability for surface-enhanced Raman spectroscopy (SERS). Successful demonstration of the electronic behavior of micromechanically exfoliated borophene and excitonic behavior of borophene-based heterolayers will guide future generation devices not only in electronics and excitonics, but also in thermal management, electronic packaging, hydrogen storage, hybrid energy storage, and clean energy solutions.
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Ovchinnikov postulated the possibility of ferromagnetism in organic compounds having a mixed density ofsp3andsp2carbon atoms. Such systems provide an interesting avenue for exploring magnetism in the absence of the quintessentiald- andf-block elements as ingredients. As graphene oxide (GO) and its derivatives naturally possess a mixture ofsp3andsp2carbon atoms, it is pertinent to look at them as potential candidates for Ovchinnikov ferromagnetism. We have looked at the evolution of magnetic property in a series of GO samples with a gradual increase in the degree of oxidation and hence thesp3/sp2fraction. Starting with a GO sample with a highsp3/sp2ratio, we utilize chemical reduction technique to prepare another set of reduced graphene oxide (rGO) samples. Magnetization measurements on these samples further illustrate the importance ofsp3/sp2fraction on magnetic behavior suggesting GO and its derivatives as a potential Ovchinnikov ferromagnet candidate. The evolution of magnetic moment withsp3/sp2carbons can be utilized in carbon based spintronic applications.
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Worldwide infections and fatalities caused by the SARS-CoV-2 virus and its variants responsible for COVID-19 have significantly impeded the economic growth of many nations. People in many nations have lost their livelihoods, it has severely impacted international relations and, most importantly, health infrastructures across the world have been tormented. This pandemic has already left footprints on human psychology, traits, and priorities and is certainly going to lead towards a new world order in the future. As always, science and technology have come to the rescue of the human race. The prevention of infection by instant and repeated cleaning of surfaces that are most likely to be touched in daily life and sanitization drives using medically prescribed sanitizers and UV irradiation of textiles are the first steps to breaking the chain of transmission. However, the real challenge is to develop and uplift medical infrastructure, such as diagnostic tools capable of prompt diagnosis and instant and economic medical treatment that is available to the masses. Two-dimensional (2D) materials, such as graphene, are atomic sheets that have been in the news for quite some time due to their unprecedented electronic mobilities, high thermal conductivity, appreciable thermal stability, excellent anchoring capabilities, optical transparency, mechanical flexibility, and a unique capability to integrate with arbitrary surfaces. These attributes of 2D materials make them lucrative for use as an active material platform for authentic and prompt (within minutes) disease diagnosis via electrical or optical diagnostic tools or via electrochemical diagnosis. We present the opportunities provided by 2D materials as a platform for SARS-CoV-2 diagnosis.
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Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Teste para COVID-19/instrumentação , Teste para COVID-19/métodos , COVID-19/diagnóstico , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , SARS-CoV-2/isolamento & purificação , COVID-19/mortalidade , Humanos , Análise Espectral Raman , Transistores EletrônicosRESUMO
Agricultural decision support tools (DSTs) with weather or climate information can provide useful information to help stakeholders make operational farming decisions and adapt to increasingly variable weather or climate in the context of climate change. However, many of these DSTs are still not fully utilized. Understanding the use of DSTs can help identify strategies to promote their usage to more end-users. This study surveyed farmers (n = 2,633) and advisors (n = 2,719) across 12 states in the Midwest to draw comparisons on their usage of DSTs and factors influencing the usage. The advisors are more likely to take advantage of free and publicly available sources than farmers. Advisors are also more likely to agree on the usefulness of DSTs, feel social pressure to use DSTs, be concerned and perceive risks from variable weather, believe in climate change, and show positive attitudes towards climate change adaptation than farmers. Concerns about weather or climate, descriptive social norms, greater farm size, and general propensity to adopt a new technology are positively associated with higher adoption rate of DSTs for both farmers and advisors. Higher level of perceived behavioral control to deal with weather-related risks, injunctive social norms, gender (male), and age are positively associated with higher adoption rate of DSTs for only advisors. Positive adaptation attitude towards climate change and higher education level are positively associated with higher adoption rate of DSTs for only farmers. Unlike advisors, age is negatively associated with higher adoption rate of DSTs for farmers. Implications of our findings include DST educators leveraging social networks and reinforcing social norms to promote usage among current non-users, building up both farmers' and advisors' confidence and knowledge in using DSTs, understanding the role of advisors as "change agents" to promote DST usage among farmers, and connecting networks of "innovators" and "early adopters." With more and more DSTs developed, future scholarship can draw upon our findings to understand how to encourage DSTs adoption among current non-users and extend to other regions.
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Agricultura , Fazendeiros , Mudança Climática , Fazendas , Humanos , Masculino , Meio-Oeste dos Estados Unidos , Tempo (Meteorologia)RESUMO
Borophene, a 2D allotrope of boron and the lightest elemental Dirac material, is the latest very promising 2D material owing to its unique structural and electronic characteristics of the X3 and ß12 phases. The high atomic density on ridgelines of the ß12 phase of borophene provides a substantial orbital overlap, which leads to an excellent electron density in the conduction level and thus to a highly metallic behavior. These unique structural characteristics and electronic properties of borophene attract significant scientific interest. Herein, approaches for crystal growth/synthesis of these unique nanostructures and their potential technological applications are discussed. Various substrate-supported ultrahigh-vacuum growth techniques for borophene, such as molecular beam epitaxy, atomic layer deposition, and chemical vapor deposition, along with their challenges, are also summarized. The sonochemical exfoliation and modified Hummer's technique for the synthesis of free-standing borophene are also discussed. Solution-phase exfoliation seems to address the scalability issues and expands the applications of these unique materials to various fields, including renewable energy devices and ultrafast sensors. Furthermore, the electronic, optical, thermal, and elastic properties of borophene are thoroughly discussed and are compared with those of graphene and its "cousins." Numerous frontline applications are envisaged and an outlook is presented.
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Adoption of innovations, including adoption of conservation practices, is a topic of extensive scholarly enterprise. The diffusion of innovations literature has often examined the characteristics of three sets of variables: the adopter, the change agent, and the innovation. This literature clearly establishes the crucial role of change agents in promoting an innovation. However, what we don't know is what makes change agents want to promote a particular innovation. In this study, change agents' perceptions of the attributes of two-stage drainage ditches, an innovative agricultural drainage ditch design, are examined in order to understand what affects their willingness to promote them. Diffusion of innovation theory provides the conceptual grounding as well as the theoretical motivation for this study. The data for this study come from semi-structured interviews with 17 change agents. Results suggest that change agents perceive the relative advantage associated with two-stage ditches to be low, and that two-stage ditches might be perceived by potential adopters to be incompatible with the prevalent sociocultural beliefs about drainage ditch management. Results also indicate that change agents' perceptions of environmental benefits of adopting two-stage ditches affects their willingness to promote them. Results are more broadly informative about promoting conservation practices, and is relevant for both academicians and practitioners.
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Agricultura/métodos , Irrigação Agrícola/instrumentação , Irrigação Agrícola/métodos , Agricultura/instrumentação , Humanos , Invenções , Movimentos da Água , Abastecimento de ÁguaRESUMO
Borophene, an elemental metallic Dirac material is predicted to have unprecedented mechanical and electronic character. Need of substrate and ultrahigh vacuum conditions for deposition of borophene restricts its large-scale applications and significantly hampers the advancement of research on borophene. Herein, a facile and large-scale synthesis of freestanding atomic sheets of borophene through a novel liquid-phase exfoliation and the reduction of borophene oxide is demonstrated. Electron microscopy confirms the presence of ß12 , X3 , and their intermediate phases of borophene; X-ray photoelectron spectroscopy, and scanning tunneling microscopy, corroborated with density functional theory band structure calculations, validate the phase purity and the metallic nature. Borophene with excellent anchoring capabilities is used for sensing of light, gas, molecules, and strain. Hybrids of borophene as well as that of reduced borophene oxide with other 2D materials are synthesized, and the predicted superior performance in energy storage is explored. The specific capacity of borophene oxide is observed to be ≈4941 mAh g-1 , which significantly exceeds that of existing 2D materials and their hybrids. These freestanding borophene materials and their hybrids will create a huge breakthrough in the field of 2D materials and could help to develop future generations of devices and emerging applications.
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While conservation of natural resources on agricultural landscapes has been a priority for public agencies for more than 80 years, the ability of conservation planners to place conservation practices for enhanced environmental benefits remains elusive. To increase both adoption of conservation practices and efficient use of conservation funding, conservation planners are turning to decision support tools (DSTs), such as the Agricultural Conservation Planning Framework (ACPF). However, less is known about how DSTs facilitate a whole-landscape approach to conservation planning, and the strategies that are employed by conservation planners to engage with producers using new GIS-enabled planning technologies. With the goal of contributing to both the policy and practice of precision conservation, we present findings from semi-structured in-depth interviews conducted with 21 conservation professionals in six watersheds in the US Midwest. Results suggest that the ACPF encourages conservation professionals to think at a watershed scale, supports their approach to conservation planning, and helps them in watershed planning and stakeholder engagement. Results also highlight the importance of conservation professionals employing a suite of strategies, such as being mindful of the scale of producer engagement (i.e., single farm vs community based) and accounting for producers' personalities, to create 'enabling conditions' for producer engagement when adopting a precision approach to conservation. Policy recommendations for precision conservation technologies include the need to streamline and expedite the process of conservation delivery, and that DSTs are a means to an end, but not a universal remedy, because conservation planning is most effective when localized interactions of rural landscapes and social dynamics are considered in an adaptive approach.
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Agricultura , Conservação dos Recursos Naturais , Recursos NaturaisRESUMO
A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.
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A low cost, non-explosive process for the synthesis of graphene oxide (GO) is demonstrated. Using suitable choice of reaction parameters including temperature and time, this recipe does not require expensive membranes for filtration of carbonaceous and metallic residues. A pre-cooling protocol is introduced to control the explosive nature of the highly exothermic reactions during the oxidation process. This alleviates the requirement for expensive membranes and completely eliminates the explosive nature of intermediate reaction steps when compared to existing methods. High quality of the synthesized GO is corroborated using a host of characterization techniques including X-ray diffraction, optical spectroscopy, X-ray photoemission spectroscopy and current-voltage characteristics. Simple reduction protocol using ultra-violet light is demonstrated for potential application in the area of photovoltaics. Using different reduction protocols together with the proposed inexpensive method, reduced GO samples with tunable conductance over a wide range of values is demonstrated. Density functional theory is employed to understand the structure of GO. We anticipate that this scalable approach will catalyze large scale applications of GO.
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Even though transition metal dichalcogenides (TMDCs) are deemed to be novel photonic and optoelectronic 2D materials, the visible band gap being often limited to monolayer, hampers their potential in niche applications due to fabrication challenges. Uncontrollable defects and degraded functionalities at elevated temperature and under extreme environments further restrict their prospects. To address such limitations, the discovery of a new 2D material, α-PbO is reported. Micromechanical as well as sonochemical exfoliation of 2D atomic sheets of α-PbO are demonstrated and its optical behavior is investigated. Spectroscopic investigations indicate layer dependent band gaps. In particular, even multilayered PbO sheets exhibit visible band gap > 2 eV (direct) which is rare among semiconducting 2D materials. The emission lifetime of multilayer PbO atomic sheets is 7 ns (dim light) as compared to the monolayer which gives 2.5 ns lifetime and an intense light. Density functional theory calculations of layer dependent band structure of α-PbO matches well with experimental results. Experimental findings suggest that PbO atomic sheets exhibit hydrophobic nature, thermal robustness, microwave stability, anti-corrosive behaviour and acid resistance. This new low-cost, abundant and robust 2D material is expected to find many applications in the fields of electronics, optoelectronics, sensors, photocatalysis and energy storage.
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Nonpoint source pollution from agricultural land uses continues to pose one of the most significant threats to water quality in the US, with measurable impacts across local, regional, and national scales. The impact and the influence of targeted conservation efforts are directly related to the degree to which farmers are familiar with and trust the entities providing the information and/or outreach. Recent research suggests that farmers consistently rank independent and retail-affiliated crop advisers as among the most trusted and influential sources for agronomic information, but little is understood about whether farmers are willing to receive advice from crop advisers on the use of practices that conserve soil and water, and, if so, whether crop advisers will be perceived as influential. We present survey data from farmers (n = 1461) in Michigan's Saginaw Bay (Lake Huron) watershed to explore these questions. Results suggest that farmers view crop advisers as trustworthy sources of information about conservation, and influential on management practices that have large conservation implications. We discuss these results, along with perceived barriers and opportunities to crop advisers partnering with traditional conservation agencies to enhance the impact of voluntary conservation programs.