Recently, China has exerted great efforts to develop agro-industrial agglomerations and optimize the agricultural industry’s regional distribution to increase farmers’ income. This study posits that ...agro-industrial agglomeration should be “dual body,” provides a theoretical framework for agro-industrial agglomeration’s effects on farmer income, and uses a spatial panel model to prove its influence on farmers’ income and the spatial spillover effect. The results show that agro-industrial agglomeration in a specific region significantly impacts farmers’ income and also has a spillover effect on income in adjacent regions. Further research shows that, contrary to traditional agglomeration theory, agricultural industry agglomeration has little impact on farmers’ agricultural production but primarily promotes the establishment and development of agricultural organizations, thus improving farmers’ income. Finally, the paper discusses the positive and negative effects of agro-industrial agglomeration on the Global Sustainable Development Goals(SDGs), and proposes some useful suggestions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Electrochemical water splitting powered by renewable energy sources has been considered as an attractive hydrogen generation technology with high‐purity product and zero carbon emission. However, the ...efficient realization of large‐scale water splitting is severely hampered by the sluggish hydrogen/oxygen evolution reaction (HER/OER). As an important class of functional materials, complex hollow electrocatalysts provide promising solutions to accelerate the HER/OER kinetics owing to their advantageous features, such as abundant exposed active sites, increased contact area between catalysts and electrolyte, and shortened mass/charge transport length. Herein, the recent advances in the development of complex hollow electrocatalysts and their outstanding performances in water splitting are summarized. Beginning with the introduction of reaction mechanisms and design principles, achievements in engineering complex hollow HER/OER electrocatalysts are highlighted with the focus on structural modulation, composition control, and electrocatalytic evaluation. Finally, some present challenges and future perspectives for advanced complex hollow electrocatalysts toward water splitting are further discussed.
Complex hollow nanostructures have attracted considerable interest in energy applications. In addition, the available component regulation could endow them with a further improved intrinsic activity. Herein, the recent progress in the design of micro‐/nanostructured hollow structures for water splitting is discussed according to the regulatory strategies of geometrical structure control and composition control. Some emergent opportunities and perspectives on the future research trends of hollow structures are also proposed.
Using the density functional theory calculations, we systematically investigate the structures and properties of silicene-like SiX and XSi3 (X = B, C, N, Al, P) hexagonal heterosheets. For the SiX ...systems, the SiP sheet favors a chairlike buckled structure akin to silicene, the SiB, SiN, and SiAl ones prefer the washboard-like buckling type, and the SiC sheet adopts the flat plane as graphene. The planarity is also favored in the XSi3 sheets with X = B, C, Al, while the rests with X = N and P prefer the chairlike buckled structures. The energetic stabilities and mechanical properties are also investigated for these SiX and XSi3 systems, and all the heterosheets are found to be stable. Unlike the semimetallic silicene, most of the SiX sheets are transformed to metals except for the SiC one with a wide band gap. For the XSi3 systems, they can be metals, semimetals, or narrow-band gap semiconductors depending on the X elements. The BSi3 and NSi3 sheets exhibit metallic behaviors, which behave like the p-type or n-type doping into silicene. On the other hand, the AlSi3 and PSi3 ones turn to semiconductors with narrow indirect band gaps, which are dominated by the Si–Si and Si–X bonding/antibonding states. Of particular interests, we find the CSi3 sheet maintains the zero-band gap semimetallicity of silicene, for which the p z orbitals of Si and C atoms contribute to the linear Dirac-like bands near the Fermi level. The dynamical stabilities of the CSi3, AlSi3, and PSi3 sheets are further examined by phonon calculations and ab initio molecular dynamics simulations, which confirm the robust stability of their free-standing states. Our studies demonstrate that the Si-related heterosheets have peculiar structures and properties, which have potential applications in the nanoelectronics and devices.
Lightweight virtualization (LV) technologies have refashioned the world of software development by introducing flexibility and new ways of managing and distributing software. Edge computing ...complements today's powerful centralized data centers with a large number of distributed nodes that provide virtualization close to the data source and end users. This emerging paradigm offers ubiquitous processing capabilities on a wide range of heterogeneous hardware characterized by different processing power and energy availability. The scope of this article is to present an in-depth analysis on the requirements of edge computing from the perspective of three selected use cases that are particularly interesting for harnessing the power of the Internet of Things. We discuss and compare the applicability of two LV technologies, containers and unikernels, as platforms for enabling the scalability, security, and manageability required by such pervasive applications that soon may be part of our everyday lives. To inspire further research, we identify open problems and highlight future directions to serve as a road map for both industry and academia.
Intestinal microbial communities have profound effects on host physiology. Whereas the symbiotic contribution of commensal bacteria is well established, the role of eukaryotic viruses that are ...present in the gastrointestinal tract under homeostatic conditions is undefined. Here we demonstrate that a common enteric RNA virus can replace the beneficial function of commensal bacteria in the intestine. Murine norovirus (MNV) infection of germ-free or antibiotic-treated mice restored intestinal morphology and lymphocyte function without inducing overt inflammation and disease. The presence of MNV also suppressed an expansion of group 2 innate lymphoid cells observed in the absence of bacteria, and induced transcriptional changes in the intestine associated with immune development and type I interferon (IFN) signalling. Consistent with this observation, the IFN-α receptor was essential for the ability of MNV to compensate for bacterial depletion. Importantly, MNV infection offset the deleterious effect of treatment with antibiotics in models of intestinal injury and pathogenic bacterial infection. These data indicate that eukaryotic viruses have the capacity to support intestinal homeostasis and shape mucosal immunity, similarly to commensal bacteria.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Developing high-performance catalysts for the chemical fixation of CO
2
into epoxides remains an ongoing hot yet challenging issue in the field of catalysis. Metal-organic frameworks (MOFs) represent ...an attractive type of catalyst candidate for this reaction due to their remarkable properties including large surface area, high stability, open channels, and permanent porosity. Although the Cu-HKUST-1 MOF has recently been shown to exhibit good activity towards CO
2
fixation, and a series of other isostructural analogues,
i.e.
, M-HKUST-1 (M = Mo, Cr, Fe, Ru and Zn), have even been synthesized, there is no theoretical investigation on CO
2
cycloaddition catalyzed by both the parent and metal-substituted HKUST-1, to the best of our knowledge. In this work, with the attempt to design powerful catalysts, we computationally screened a series of M-HKUST-1 systems (M = Mo, Cr, Ti, Cu, W, Sc, Fe, Ru, Zn, Cd, and V) in the presence of quaternary ammonium salts (TBAX, X = F, Cl, Br, and I) for catalytic activity toward the synthesis of cyclic carbonates from propylene oxide (PO) and CO
2
. Of these, several M-HKUST-1 systems (M = Cr, W, Fe, Zn, and Cd) were predicted to exceed the performance of the original Cu-HKUST-1 reported experimentally for CO
2
chemical conversion based on the rate-limiting energy barrier. In particular, W-HKUST-1 was predicted to be the most promising catalyst within the screened M-HKUST-1 series. In addition, for Cu-HKUST-1, the catalyst system containing Br
−
is more efficient than the one containing F
−
, Cl
−
and I
−
. The proton attachment energy of the X
−
anion is a suitable descriptor for screening promising co-catalytic materials for the specific reaction. The present computational investigation would greatly enrich the CO
2
-PO reaction catalyzed by M-HKUST-1/TBAX, and provide a valuable guideline for the design of more powerful MOFs/IL catalysts.
This work would enrich the CO
2
-PO reaction catalyzed by M-HKUST-1/TBAX and provide a guideline for the design of more powerful catalysts.
Virtual reality (VR) is an innovation that permits the individual to discover and operate within three-dimensional (3D) environment to gain practical understanding. This research aimed to examine the ...general efficiency of VR for teaching medical anatomy.
We executed a meta-analysis of randomized controlled studies of the performance of VR anatomy education. We browsed five databases from the year 1990 to 2019. Ultimately, 15 randomized controlled trials with a teaching outcome measure analysis were included. Two authors separately chose studies, extracted information, and examined the risk of bias. The primary outcomes were examination scores of the students. Secondary outcomes were the degrees of satisfaction of the students. Random-effects models were used for the pooled evaluations of scores and satisfaction degrees. Standardized mean difference (SMD) was applied to assess the systematic results. The heterogeneity was determined by I
statistics, and then was investigated by meta-regression and subgroup analyses.
In this review, we screened and included fifteen randomized controlled researches (816 students). The pooled analysis of primary outcomes showed that VR improves test scores moderately compared with other approaches (standardized mean difference SMD = 0.53; 95% Confidence Interval CI 0.09-0.97, p < 0.05; I
= 87.8%). The high homogeneity indicated that the studies were different from each other. Therefore, we carried out meta-regression as well as subgroup analyses using seven variables (year, country, learners, course, intervention, comparator, and duration). We found that VR improves post-intervention test score of anatomy compared with other types of teaching methods.
The finding confirms that VR may act as an efficient way to improve the learners' level of anatomy knowledge. Future research should assess other factors like degree of satisfaction, cost-effectiveness, and adverse reactions when evaluating the teaching effectiveness of VR in anatomy.
Conjugated polymers usually form crystallized and amorphous regions in the solid state simultaneously, making it difficult to accurately determine their precise microstructures. The lack of ...multiscale microstructures of conjugated polymers limits the fundamental understanding of the structure–property relationships in polymer‐based optoelectronic devices. Here, crystals of two typical conjugated polymers based on four‐fluorinated benzodifurandione‐based oligo(p‐phenylene vinylene) (F4BDOPV) and naphthalenediimide (NDI) motifs, respectively, are obtained by a controlled self‐assembly process. The strong diffractivity of the polymer crystals brings an opportunity to determine the crystal structures by combining X‐ray techniques and molecular simulations. The precise polymer packing structures are useful as initial models to evaluate the charge transport properties in the ordered and disordered phases. Compared to the spin‐coated thin films, the highly oriented polymer chains in crystals endow higher mobilities with a lower hopping energy barrier. Microwire crystal transistors of F4BDOPV‐ and NDI‐based polymers exhibit high electron mobilities of up to 5.58 and 2.56 cm2 V−1 s−1, respectively, which are among the highest values in polymer crystals. This work presents a simple method to obtain polymer crystals and their precise microstructures, promoting a deep understanding of molecular packing and charge transport for conjugated polymers.
Conjugated polymer microwire crystals are obtained from solvated aggregates. The precise crystal packing and electronic structure in the polymer microwires are evaluated for understanding of the charge transport properties. Polymer crystal transistors of F4BDOPV‐2T exhibit higher electron mobilities of up to 5.58 cm2 V−1 s−1 with a much lower hopping energy barrier compared with conventional thin‐film transistors.
Molecular packing in organic single crystals greatly influences their charge transport properties but can hardly be predicted and designed because of the complex intermolecular interactions. In this ...work, we have realized systematic fine-tuning of the single-crystal molecular packing of five benzodifurandione-based oligo(p-phenylenevinylene) (BDOPV)-based small molecules through incorporation of electronegative fluorine atoms on the BDOPV backbone. While these molecules all exhibit similar column stacking configurations in their single crystals, the intermolecular displacements and distances can be substantially modified by tuning of the amounts and/or the positions of the substituent fluorine atoms. Density functional theory calculations showed that the subtle differences in charge distribution or electrostatic potential induced by different fluorine substitutions play an important role in regulating the molecular packing of the BDOPV compounds. Consequently, the electronic couplings for electron transfer can vary from 71 meV in a slipped stack to 201 meV in a nearly cofacial antiparallel stack, leading to an increase in the electron mobility of the BDOPV derivatives from 2.6 to 12.6 cm2 V–1 s–1. The electron mobility of the five molecules did not show a good correlation with the LUMO levels, indicating that the distinct difference in charge transport properties is a result of the molecular packing. Our work not only provides a series of high-electron-mobility organic semiconductors but also demonstrates that fluorination is an effective approach for fine-tuning of single-crystal packing modes beyond simply lowering the molecular energy levels.
Conjugated polymers with high thermoelectric performance enable the fabrication of low‐cost, large‐area, low‐toxicity, and highly flexible thermoelectric devices. However, compared to their p‐type ...counterparts, n‐type polymer thermoelectric materials show much lower performance, which is largely due to inefficient doping and a much lower conductivity. Herein, it is reported that the development of a donor–acceptor (D–A) polymer with enhanced n‐doping efficiency through donor engineering of the polymer backbone. Both a high n‐type electrical conductivity of 1.30 S cm−1 and an excellent power factor (PF) of 4.65 µW mK−2 are obtained, which are the highest reported values among D–A polymers. The results of multiple characterization techniques indicate that electron‐withdrawing modification of the donor units enhances the electron affinity of the polymer and changes the polymer packing orientation, leading to substantially improved miscibility and n‐doping efficiency. Unlike previous studies in which improving the polymer‐dopant miscibility typically resulted in lower mobilities, the strategy maintains the mobility of the polymer. All these factors lead to prominent enhancement of three orders magnitude in both the electrical conductivity and the PF compared to those of the non‐engineered polymer. The results demonstrate that proper donor engineering can enhance the n‐doping efficiency, electrical conductivity, and thermoelectric performance of D–A copolymers.
1000‐fold enhancements in n‐type electrical conductivity and power factor of a donor–acceptor copolymer are obtained by donor engineering. Donor engineering enhances electron affinity and n‐doping efficiency, prevents phase separation, lowers hopping barrier and keeps mobility unaffected. A record electrical conductivity of 1.30 S cm−1 and a power factor of 4.65 μW mK−2 are achieved in this work.
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