Showing papers by "Southwest University published in 2018"

Pursuing sustainable productivity with millions of smallholder farmers.

Abstract: Millions of Chinese smallholder farmers were persuaded to adopt enhanced management practices, which led to a greater yield, reduced nitrogen fertilizer use and improved environmental performance throughout China. Two and a half billion smallholder farmers collectively manage 60 per cent of the world's arable land. How these farmers perform determines their own livelihood, but also affects global food security and ecosystem health. Here, Fusuo Zhang and colleagues show how some straightforward interventions have substantially improved the productivity and environmental performance of smallholder farmers across China over the past ten years. The team carried out more than 13,000 field trials across China's main agroecological zones and found that a series of management practices, collectively termed integrated soil–crop system management, increased maize, wheat and rice yields, nitrogen-use efficiency and farmer profitability. Scaling this approach up to 20.9 million smallholder farmer across 452 counties boosted grain yields to 33 million tonnes over the ten-year period, and reduced fertilizer use by 1.2 million tonnes and greenhouse gas emissions by up to 13 per cent. Sustainably feeding a growing population is a grand challenge1,2,3, and one that is particularly difficult in regions that are dominated by smallholder farming. Despite local successes4,5,6,7,8, mobilizing vast smallholder communities with science- and evidence-based management practices to simultaneously address production and pollution problems has been infeasible. Here we report the outcome of concerted efforts in engaging millions of Chinese smallholder farmers to adopt enhanced management practices for greater yield and environmental performance. First, we conducted field trials across China’s major agroecological zones to develop locally applicable recommendations using a comprehensive decision-support program. Engaging farmers to adopt those recommendations involved the collaboration of a core network of 1,152 researchers with numerous extension agents and agribusiness personnel. From 2005 to 2015, about 20.9 million farmers in 452 counties adopted enhanced management practices in fields with a total of 37.7 million cumulative hectares over the years. Average yields (maize, rice and wheat) increased by 10.8–11.5%, generating a net grain output of 33 million tonnes (Mt). At the same time, application of nitrogen decreased by 14.7–18.1%, saving 1.2 Mt of nitrogen fertilizers. The increased grain output and decreased nitrogen fertilizer use were equivalent to US$12.2 billion. Estimated reactive nitrogen losses averaged 4.5–4.7 kg nitrogen per Megagram (Mg) with the intervention compared to 6.0–6.4 kg nitrogen per Mg without. Greenhouse gas emissions were 328 kg, 812 kg and 434 kg CO2 equivalent per Mg of maize, rice and wheat produced, respectively, compared to 422 kg, 941 kg and 549 kg CO2 equivalent per Mg without the intervention. On the basis of a large-scale survey (8.6 million farmer participants) and scenario analyses, we further demonstrate the potential impacts of implementing the enhanced management practices on China’s food security and sustainability outlook.

Energy-Efficient Data Collection in UAV Enabled Wireless Sensor Network

Abstract: In wireless sensor networks, utilizing the unmanned aerial vehicle (UAV) as a mobile data collector for the sensor nodes (SNs) is an energy-efficient technique to prolong the network lifetime. In this letter, considering a general fading channel model for the SN-UAV links, we jointly optimize the SNs’ wake-up schedule and UAV’s trajectory to minimize the maximum energy consumption of all SNs, while ensuring that the required amount of data is collected reliably from each SN. We formulate our design as a mixed-integer non-convex optimization problem. By applying the successive convex optimization technique, an efficient iterative algorithm is proposed to find a sub-optimal solution. Numerical results show that the proposed scheme achieves significant network energy saving as compared to benchmark schemes.

Robust prediction of individual creative ability from brain functional connectivity

Abstract: People’s ability to think creatively is a primary means of technological and cultural progress, yet the neural architecture of the highly creative brain remains largely undefined. Here, we employed a recently developed method in functional brain imaging analysis—connectome-based predictive modeling—to identify a brain network associated with high-creative ability, using functional magnetic resonance imaging (fMRI) data acquired from 163 participants engaged in a classic divergent thinking task. At the behavioral level, we found a strong correlation between creative thinking ability and self-reported creative behavior and accomplishment in the arts and sciences (r = 0.54). At the neural level, we found a pattern of functional brain connectivity related to high-creative thinking ability consisting of frontal and parietal regions within default, salience, and executive brain systems. In a leave-one-out cross-validation analysis, we show that this neural model can reliably predict the creative quality of ideas generated by novel participants within the sample. Furthermore, in a series of external validation analyses using data from two independent task fMRI samples and a large task-free resting-state fMRI sample, we demonstrate robust prediction of individual creative thinking ability from the same pattern of brain connectivity. The findings thus reveal a whole-brain network associated with high-creative ability comprised of cortical hubs within default, salience, and executive systems—intrinsic functional networks that tend to work in opposition—suggesting that highly creative people are characterized by the ability to simultaneously engage these large-scale brain networks.

Chilling and Drought Stresses in Crop Plants: Implications, Cross Talk, and Potential Management Opportunities

Abstract: Plants face a combination of different abiotic stresses under field conditions which are lethal to plant growth and production. Simultaneous occurrence of chilling and drought stresses in plants due to the drastic and rapid global climate changes, can alter the morphological, physiological and molecular responses. Both these stresses adversely affect the plant growth and yields due to physical damages, physiological and biochemical disruptions, and molecular changes. In general, the co-occurrence of chilling and drought combination is even worse for crop production rather than an individual stress condition. Plants attain various common and different physiological and molecular protective approaches for tolerance under chilling and drought stresses. Nevertheless, plant responses to a combination of chilling and drought stresses are unique from those to individual stress. In the present review, we summarized the recent evidence on plant responses to chilling and drought stresses on shared as well as unique basis and tried to find a common thread potentially underlying these responses. We addressed the possible cross talk between plant responses to these stresses and discussed the potential management strategies for regulating the mechanisms of plant tolerance to drought and/or chilling stresses. To date, various novel approaches have been tested in minimizing the negative effects of combine stresses. Despite of the main improvements there is still a big room for improvement in combination of drought and chilling tolerance. Thus, future researches particularly using biotechnological and molecular approaches should be carried out to develop genetically engineered plants with enhanced tolerance against these stress factors.

A critical review of the use of virtual reality in construction engineering education and training

Abstract: Virtual Reality (VR) has been rapidly recognized and implemented in construction engineering education and training (CEET) in recent years due to its benefits of providing an engaging and immersive environment. The objective of this review is to critically collect and analyze the VR applications in CEET, aiming at all VR-related journal papers published from 1997 to 2017. The review follows a three-stage analysis on VR technologies, applications and future directions through a systematic analysis. It is found that the VR technologies adopted for CEET evolve over time, from desktop-based VR, immersive VR, 3D game-based VR, to Building Information Modelling (BIM)-enabled VR. A sibling technology, Augmented Reality (AR), for CEET adoptions has also emerged in recent years. These technologies have been applied in architecture and design visualization, construction health and safety training, equipment and operational task training, as well as structural analysis. Future research directions, including the integration of VR with emerging education paradigms and visualization technologies, have also been provided. The findings are useful for both researchers and educators to usefully integrate VR in their education and training programs to improve the training performance.

Chemically Exfoliating Biomass into a Graphene‐like Porous Active Carbon with Rational Pore Structure, Good Conductivity, and Large Surface Area for High‐Performance Supercapacitors

Abstract: DOI: 10.1002/aenm.201702545 various important applications, especially in energy conversion/storage due to their large surface area, good electrical conductivity, great physicochemical stability, and high surface reactivity.[1–9] In these carbons, 2D materials, such as graphene, have drawn much more attention because their low-dimension structure could shorten ion-diffusion length and realize fast electron transfer in an electrochemical reaction process. Extensive efforts have been devoted to controllably exfoliate graphite into 2D carbon materials.[10–13] ACs have been broadly used for various application over the past years due to their low cost, high specific surface area, and rich porous structure, but their conductivity and ratio of surface to weight are still not comparable with graphene.[14–16] ACs are normally derived from various carbon-rich organic precursors by carbonization at high temperatures following by different activation process such as treatments with KOH, ZnCl2, and H3PO4. ACs can have high porosity, large specific surface area (≈2000 m2 g−1) and excellent adsorption capacity through different activation processes; however, the currently used carbonrich organic precursors are easily to result in large aggregates and end-died pores at high temperature carbonization for poor accessibility of reactants and/or ions, low conductivity, and low utilization in energy storage devices.[22,23] Post-treatment of carbon materials can punch pores only on the surface of bulk carbon and is hard to destroy chemical forces between aggregated layers for separation. Graphene-like lamellar nanomaterials can have inherent advantages of high ratio of surface area to weight, high exposure surface atoms, and fast charge transport behavior. The space and channels between the lamellar layers can greatly boost ions or/and reactants accessibility and significantly shorten the diffusion length to an electrode. It is also very meaningful to convert biomass into valuable carbons,[24–26] in particular for “waste-to-wealth” purpose. Chemical modification for biomass is much easier than that for carbon materials. Moreover, chemical modification and biomass carbonization will induce heteroatoms into carbon materials to tailor the carbon electron-donor properties, the electrical and chemical behaviors of carbons. Active carbons have unique physicochemical properties, but their conductivities and surface to weight ratios are much poorer than graphene. A unique and facile method is innovated to chemically process biomass by “drilling” holes with H2O2 and exfoliating into graphene-like nanosheets with HAc, followed by carbonization at a high temperature for highly graphitized activated carbon with greatly enhanced porosity, unique pore structure, high conductivity, and large surface area. This graphene-like carbon exhibits extremely high specific capacitance (340 F g−1 at 0.5 A g−1) and high specific energy density (23.33 to 16.67 W h kg−1) with excellent rate capability and long cycling stability (remains 98% after 10 000 cycles), which is much superior to all reported carbons including graphene. Synthesis mechanism for deriving biomass into porous graphene-like carbons is discussed in detail. The enhancement mechanism for the porous graphene-like carbon electrode reveals that rationally designed mesoand macropores are very critical in porous electrode performance, which can network micropores for diffusion freeways, high conductivity, and high utilization. This work has universal significance in producing highly porous and conductive carbons from biomass including biowastes for various energy storage/conversion applications.

Advances in cellulose nanomaterials

Abstract: Research on nanocellulose has significantly increased over the past few decades, owing to the various attractive characteristics of this material, such as renewability, widespread availability, low density, excellent mechanical properties, economic value, biocompatibility, and biodegradability. Nanocellulose categorized into two main types, namely cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs). In this review, we present the recent advances made in the production of CNFs and CNCs. In addition to the conventional mechanical and chemical treatments used to prepare CNFs and CNCs, respectively, other promising techniques as well as pretreatment processes have been also proposed in recent times, in an effort to design an economically efficient and eco-friendly production route for nanocellulose. Further, while the hydrophilic nature of nanocellulose limits its use in polymeric matrices and in some industrial applications, the large number of hydroxyl groups on the surface of nanocellulose provides a suitable platform for various kinds of modification treatments. The various chemical and physical surface treatment procedures reported for nanocellulose have been reviewed in this paper. Finally, in this review, we summarize the life cycle assessment studies conducted so far on nanocellulose, which quantify the environmental impact of nanocellulose products. The current paper is a comprehensive review of the recent literature on nanostructured cellulose.

Economics- and policy-driven organic carbon input enhancement dominates soil organic carbon accumulation in Chinese croplands.

Abstract: China's croplands have experienced drastic changes in management practices, such as fertilization, tillage, and residue treatments, since the 1980s. There is an ongoing debate about the impact of these changes on soil organic carbon (SOC) and its implications. Here we report results from an extensive study that provided direct evidence of cropland SOC sequestration in China. Based on the soil sampling locations recorded by the Second National Soil Survey of China in 1980, we collected 4,060 soil samples in 2011 from 58 counties that represent the typical cropping systems across China. Our results showed that across the country, the average SOC stock in the topsoil (0-20 cm) increased from 28.6 Mg C ha-1 in 1980 to 32.9 Mg C ha-1 in 2011, representing a net increase of 140 kg C ha-1 year-1 However, the SOC change differed among the major agricultural regions: SOC increased in all major agronomic regions except in Northeast China. The SOC sequestration was largely attributed to increased organic inputs driven by economics and policy: while higher root biomass resulting from enhanced crop productivity by chemical fertilizers predominated before 2000, higher residue inputs following the large-scale implementation of crop straw/stover return policy took over thereafter. The SOC change was negatively related to N inputs in East China, suggesting that the excessive N inputs, plus the shallowness of plow layers, may constrain the future C sequestration in Chinese croplands. Our results indicate that cropland SOC sequestration can be achieved through effectively manipulating economic and policy incentives to farmers.

Nanosized Metal Phosphides Embedded in Nitrogen‐Doped Porous Carbon Nanofibers for Enhanced Hydrogen Evolution at All pH Values

Abstract: Transition-metal phosphides (TMPs) have emerged as promising catalyst candidates for the hydrogen evolution reaction (HER). Although numerous methods have been investigated to obtain TMPs, most rely on traditional synthetic methods that produce materials that are inherently deficient with respect to electrical conductivity. An electrospinning-based reduction approach is presented, which generates nickel phosphide nanoparticles in N-doped porous carbon nanofibers (Ni2 P@NPCNFs) in situ. Ni2 P nanoparticles are protected from irreversible fusion and aggregation in subsequent high-temperature pyrolysis. The resistivity of Ni2 P@NPCNFs (5.34 Ω cm) is greatly decreased by 104 times compared to Ni2 P (>104 Ω cm) because N-doped carbon NFs are incorporated. As an electrocatalyst for HER, Ni2 P@NPCNFs reveal remarkable performance compared to other previously reported catalysts in acidic media. Additionally, it offers excellent catalytic ability and durability in both neutral and basic media. Encouraged by the excellent electrocatalytic performance of Ni2 P@NPCNFs, a series of pea-like Mx P@NPCNFs, including Fe2 P@NPCNFs, Co2 P@NPCNFs, and Cu3 P@NPCNFs, were synthesized by the same method. Detailed characterization suggests that the newly developed method could render combinations of ultrafine metal phosphides with porous carbon accessible; thereby, extending opportunities in electrocatalytic applications.

The Heihe Integrated Observatory Network: A Basin-Scale Land Surface Processes Observatory in China

Abstract: Research on land surface processes at the catchment scale has drawn much attention over the past few decades, and a number of watershed observatories have been established worldwide. The Heihe River Basin (HRB), which contains the second largest inland river in China, is an ideal natural field experimental area for investigation of land surface processes involving diverse landscapes and the coexistence of cold and arid regions. The Heihe Integrated Observatory Network was established in 2007. For long-term observations, a hydrometeorological observatory, ecohydrological wireless sensor network, and satellite remote sensing are now in operation. In 2012, a multiscale observation experiment on evapotranspiration over heterogeneous land surfaces was conducted in the midstream region of the HRB, which included a flux observation matrix, wireless sensor network, airborne remote sensing, and synchronized ground measurements. Under an open data policy, the datasets have been publicly released following careful data processing and quality control. The outcomes highlight the integrated research on land surface processes in the HRB and include observed trends, scaling methods, high spatiotemporal resolution remote sensing products, and model–data integration in the HRB, all of which are helpful to other endorheic basins in the “Silk Road Economic Belt.” Henceforth, the goal of the Heihe Integrated Observatory Network is to develop an intelligent monitoring system that incorporates ground-based observatory networks, unmanned aerial vehicles, and multi-source satellites through the Internet of Things technology. Furthermore, biogeochemical processes observation will be improved, and the study of integrating ground observations, remote sensing, and large-scale models will be promoted further.

Recent advances in the construction and analytical applications of metal-organic frameworks-based nanozymes

Abstract: The nanozymes are a kind of synthetic nanomaterials with enzyme-like properties. Metal–organic frameworks (MOFs) are an important class of inorganic–organic hybrid crystals. Their unique composition, structural diversity and size tailorability enable them to be promising for the construction of novel nanozymes. This review intends to summarize the recent advance for the construction of MOFs-based nanozymes and their primary applications in chemical sensing and biosensing. Based on their synthetical strategies, the MOFs-based nanozymes are categorized into four classes: pristine MOFs, MOFs with chemical modification, MOFs-based composites and MOF derivatives. In each categorization, the design and enzyme mimetic activity are discussed. Moreover, the analytical applications of these nanozymes are covered, such as the detection of H2O2, small biomolecules releasing H2O2, reductive small biomolecules, biomacromolecules, heavy metal ions, toxic metabolite of fungi, antibiotics, and so on. Finally, a summary and future perspective on the applications of MOFs-based nanozymes are briefly discussed.

Honeycomb‐Like Spherical Cathode Host Constructed from Hollow Metallic and Polar Co9S8 Tubules for Advanced Lithium–Sulfur Batteries

Abstract: The practical application of lithium-sulfur (Li-S) batteries remains remote because of rapid capacity fade caused by the low conductivity of sulfur, dissolution of intermediate lithium polysulfides, severe volumetric expansion, and slow redox kinetics of polysulfide intermediates. Here, to address these obstacles, a new sulfiphilic and highly conductive honeycomb-like spherical cathode host constructed from hollow metallic and polar Co9S8 tubes is designed. Co9S8 can effectively bind polar polysulfides for prolonged cycle life, due to the strong chemisorptive capability for immobilizing the polysulfide species. The hollow structure, as the sulfur host, can further prevent polysulfide dissolution and offer sufficient space to accommodate the necessary volume expansion. Well-aligned tubular arrays provide a conduit for rapid conduction of electrons and Li-ions. More importantly, the experimental results and theoretical calculations show that Co9S8 plays an important catalytic role in improving the electrochemical reaction kinetics. When used as cathode materials for Li–S batteries, the S@Co9S8 composite cathode exhibits high capacity and an exceptional stable cycling life demonstrated by tests of 600 cycles at 1 C with a very low capacity decay rate of only ≈0.026% per cycle.

Betaine in Inflammation: Mechanistic Aspects and Applications.

Abstract: Betaine is known as trimethylglycine (TMG) and is widely distributed in animals, plants and microorganisms. Betaine is known to function physiologically as an important osmoprotectant and methyl group donor. Accumulating evidence has shown that betaine has anti-inflammatory functions in numerous diseases. Mechanistically, betaine ameliorates sulfur amino acid (SAA) metabolism against oxidative stress, inhibits nuclear factor-κB (NF-κB) activity and NLRP3 inflammasome activation, regulates energy metabolism, and mitigates endoplasmic reticulum (ER) stress and apoptosis. Consequently, betaine has beneficial actions in several human diseases, such as obesity, diabetes, cancer and Alzheimer’s disease.

Magnesium Oxide Nanoparticles: Effective Agricultural Antibacterial Agent Against Ralstonia solanacearum.

Abstract: Magnesium (Mg) is an essential mineral element for plants and is nontoxic to organisms. In this study, we took advantage of nanotechnologies to systematically investigate the antibacterial mechanisms of magnesium oxide nanoparticles (MgONPs) against the phytopathogen Ralstonia solanacearum (R. solanacearum) in vitro and in vivo for the first time. R. solanacearum has contributed to catastrophic bacterial wilt, which has resulted in the world-wide reduction of tobacco production. The results demonstrated that MgONPs possessed statistically significant concentration-dependent antibacterial activity, and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were measured as 200 and 250 μg/mL, respectively. Additional studies, aimed at understanding the toxicity mechanism of MgONPs, indicated that physical injury occurred to the cell membranes, along with decreased motility and biofilm formation ability of R. solanacearum, due to the direct attachment of MgONPs to the surfaces of the bacterial cells, which was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Reactive oxygen species (ROS) accumulation could also be an important reason for the antibacterial action, inducing DNA damage. The toxicity assessment assay under greenhouse conditions demonstrated that the MgONPs had exerted a large effect on tobacco bacterial wilt, reducing the bacterial wilt index. Altogether, the results suggest that the development of MgONPs as alternative antibacterial agents will become a new research subject.

Distributed Optimal Consensus Over Resource Allocation Network and Its Application to Dynamical Economic Dispatch

Abstract: The resource allocation problem is studied and reformulated by a distributed interior point method via a $\theta$ - logarithmic barrier. By the facilitation of the graph Laplacian, a fully distributed continuous-time multiagent system is developed for solving the problem. Specifically, to avoid high singularity of the $\theta$ - logarithmic barrier at boundary, an adaptive parameter switching strategy is introduced into this dynamical multiagent system. The convergence rate of the distributed algorithm is obtained. Moreover, a novel distributed primal–dual dynamical multiagent system is designed in a smart grid scenario to seek the saddle point of dynamical economic dispatch, which coincides with the optimal solution. The dual decomposition technique is applied to transform the optimization problem into easily solvable resource allocation subproblems with local inequality constraints. The good performance of the new dynamical systems is, respectively, verified by a numerical example and the IEEE six-bus test system-based simulations.

Pt nanoparticles decorated SnO2 nanoneedles for efficient CO gas sensing applications

Abstract: Herein, we report the synthesis, characterization, and gas sensing applications of Pt nanoparticles-decorated SnO 2 nanoneedles synthesized through a facile hydrothermal process. The synthesized nanoneedles were characterized for their morphological, structural, compositional and sensing properties using different characterization techniques. The morphological and structural characterizations confirmed the synthesis of well crystalline Pt nanoparticles decorated SnO 2 nanoneedles with tetragonal rutile crystal phase. X-ray photoelectron spectroscopic analysis (XPS) confirmed the spatial distribution of Pt metal into SnO 2 nanoneedles. Further, gas sensor applications of the synthesized nanoneedles were studies at different operating temperatures and concentrations of the CO gas. The detailed CO gas sensing analysis revealed that at an optimized temperature of 250 °C, the sensor exhibited 23.18 gas response with the response and recovery times of 15 s and 14 s, respectively. The long-term stability and the selectivity of the 3.125 at% Pt-decorated SnO 2 nanoneedles were also explored. Finally, a plausible gas sensing mechanism was also proposed.

Advances in Targeted Pesticides with Environmentally Responsive Controlled Release by Nanotechnology.

Abstract: Pesticides are the basis for defending against major biological disasters and important for ensuring national food security. Biocompatible, biodegradable, intelligent, and responsive materials are currently an emerging area of interest in the field of efficient, safe, and green pesticide formulation. Using nanotechnology to design and prepare targeted pesticides with environmentally responsive controlled release via compound and chemical modifications has also shown great potential in creating novel formulations. In this review, special attention has been paid to intelligent pesticides with precise controlled release modes that can respond to micro-ecological environment changes such as light-sensitivity, thermo-sensitivity, humidity sensitivity, soil pH, and enzyme activity. Moreover, establishing intelligent and controlled pesticide release technologies using nanomaterials are reported. These technologies could increase pesticide-loading, improve the dispersibility and stability of active ingredients, and promote target ability.

Highly Ordered and Field-Free 3D DNA Nanostructure: The Next Generation of DNA Nanomachine for Rapid Single-Step Sensing.

Abstract: Herein, by directly using Watson–Crick base pairing, a highly ordered and field-free three-dimensional (3D) DNA nanostructure is self-assembled by azobenzene (azo)-functionalized DNA nippers in a few minutes, which was applied as a 3D DNA nanomachine with an improved movement efficiency compared to traditional Au-based 3D nanomachines due to the organized and high local concentration of nippers on homogeneous DNA nanostructure. Once microRNA (miRNA) interacts with the 3D nanomachine, the nippers “open” to hybridize with the miRNA. Impressively, photoisomerization of the azo group induces dehybridization/hybridization of the nippers and miRNA under irradiation at different wavelengths, which easily solves one main technical challenge of DNA nanotechnology and biosensing: reversible locomotion in one step within 10 min. As a proof of concept, the described 3D machine is successfully applied in the rapid single-step detection of a biomarker, which gives impetus to the design of new generations of mechanical ...

The Role of Mitochondria in Reactive Oxygen Species Generation and Its Implications for Neurodegenerative Diseases.

Abstract: Mitochondria are dynamic cellular organelles that consistently migrate, fuse, and divide to modulate their number, size, and shape. In addition, they produce ATP, reactive oxygen species, and also have a biological role in antioxidant activities and Ca2+ buffering. Mitochondria are thought to play a crucial biological role in most neurodegenerative disorders. Neurons, being high-energy-demanding cells, are closely related to the maintenance, dynamics, and functions of mitochondria. Thus, impairment of mitochondrial activities is associated with neurodegenerative diseases, pointing to the significance of mitochondrial functions in normal cell physiology. In recent years, considerable progress has been made in our knowledge of mitochondrial functions, which has raised interest in defining the involvement of mitochondrial dysfunction in neurodegenerative diseases. Here, we summarize the existing knowledge of the mitochondrial function in reactive oxygen species generation and its involvement in the development of neurodegenerative diseases.