For developing highly selective and sensitive electrochemical sensors for chiral recognition, taking advantage of the synthetical properties of β-cyclodextrin (β-CD, strong host–guest recognition) ...and carbon nanotubes wrapped with reduced graphene oxide (CNTs@rGO, excellent electrochemical property and large surface area), as well as the differences in binding affinity between β-CD and guest molecules, a dual signal electrochemical sensing strategy was proposed herein for the first time in chiral recognition based on the competitive host–guest interaction between probe and chiral isomers with β-CD/CNTs@rGO. As a model system, rhodamine B (RhB) and phenylalanine enantiomers (d- and l-Phe) were introduced as probe and target enantiomers, respectively. Due to the host–guest interactions, RhB can enter into the β-CD cavity, showing remarkable oxidation peak current of RhB. In the presence of l-Phe, competitive interaction with the β-CD cavity occurs and RhB are replaced by l-Phe owing to the stronger binding affinity between l-Phe and β-CD, which results in the peak current of RhB decreasing and the peak current of l-Phe appears, and interestingly, the changes of both signals linearly correlate with the concentration of l-Phe. As for d-Phe, it cannot replace RhB owing to the weaker binding affinity between d-Phe and β-CD. Based on this, a dual-signal electrochemical sensor was developed successfully for recognizing Phe. This dual-signal sensing strategy can provide highly selective and sensitive recognition compared to single-signal sensor and has important potential applications in chiral recognition.
Zinc finger homeodomain (ZHD) protein is a plant-specific transcription factor and a potential regulator of phosphoenolpyruvate carboxylase (PEPCase)-coding genes, and it also participates in plant ...growth regulation and abiotic stress responses. To study the function of MsZF-HD genes in the alkaline stress response, this paper assessed biological information and performed transcriptome analysis of the MsZF-HD gene family by using the genomes of two different varieties of alfalfa (XinJiangDa Ye and Zhongmu No. 1).
In total, 49 and 11 MsZF-HD genes were identified in the two different varieties respectively, including the alleles of XinJiangDa Ye. According to their phylogenetic relationships, the 60 MsZF-HD genes were divided into 5 ZHD subfamilies and 1 MIF subfamily. A total of 88.3% of MsZF-HD genes do not contain introns and are unevenly distributed among the 6 chromosomes of alfalfa. A collinearity analysis indicated that 26 genes of XinJiangDa Ye have no orthologous genes in Zhongmu No. 1, although these genes (such as ZHD-X1-2, ZHD-X3-2 and ZHD-X4-2) have homologous genes in Arabidopsis thaliana, Medicago truncatula and Glycine max. Through RNA-seq and qRT-PCR verification, it was found that MsZF-HD genes are downregulated to participate in the alkaline stress response.
The results of this study may lay the foundation for the cloning and functional study of MsZF-HD genes and provide a theoretical basis for revealing the difference between XinJiangDa Ye and Zhongmu No. 1 at the genome level.
Self-healing concrete is a new material with the ability to autogenously heal cracks. Self-healing by encapsulated healing agents has been widely studied, while the influence of the space ...distribution of capsules or short glass tubes on healing capacity has seldom been addressed. This study investigated how to improve the self-healing capacity of specimens by the arrangement of glass tubes. A combination of a glass tube and steel fibers was prepared and it could be aligned in a matrix under a magnetic field. Three-point bending tests were carried out to test the self-healing capacity of cementitious composites with glass tubes in different directions, and the results showed that when the tubes were parallel to the direction of tensile stress, the self-healing effect was the best. The self-healing capacity of cementitious composites with aligned or random glass tubes were tested and the results showed that the self-healing effect of cementitious composites with aligned glass tubes was better than that with randomly oriented tubes. The principle of the self-healing enhancement was discussed, and it was due to an increased outflow volume of the healing agent.
Silicon quantum dots (SiQDs) were synthesized from N-3-(trimethoxysilyl)propyl-ethylenediamine and catechol by a hydrothermal method. Transmission electron microscopy, Fourier transform infrared ...spectroscopy and X-ray photoelectron spectroscopy were used to characterize the morphology and structure of quantum dots. The SiQDs were then placed on gold nanoparticles (AuNPs). When Cys is added to this solution, Cys will penetrate the SiQDs “shell” of the SiQDs/AuNP composite. This is due to the interaction and conformational differences of Cys and other substance with AuNPs and leads to the dispersion of the aggregated SiQD/AuNPs. A color change from purple to red can be visually observed, and the (green) fluorescence of SiQDs (with excitation/emission peaks at 430/520 nm) is restored. This dual-readout nanoprobe was successfully applied to the selective and sensitive detection of cysteine (Cys) in (spiked) serum and urine samples. The detection limit is 3.5 nmol·L
−1
(at an S/N ratio of 3), and the method works on the 0.01 to 2 μM Cys concentration range.
Graphical abstract
Schematic illustration of a method for synthesizing silicon quantum dots (SiQDs) and coating them on gold nanoparticles (AuNPs) as an optical probe for colorimetric and fluorometric determination of cysteine.
Establishing mixed plantations is an effective way to improve soil fertility and increase forest productivity. Arbuscular mycorrhizal (AM) fungi are obligate symbiotic fungi that can promote mineral ...nutrient absorption and regulate intraspecific and interspecific competition in plants. However, the effects of mixed plantations on the community structure and abundance of AM fungi are still unclear. Illumina MiSeq sequencing was used to investigate the AM fungal community in the roots and soils of pure and mixed plantations (Juglans mandshurica × Larix gmelinii). The objective of this study is to compare the differential responses of the root and rhizosphere soil AM fungal communities of Juglans mandshurica to long-term mixed plantation management.
Glomus and Paraglomus were the dominant genera in the root samples, accounting for more than 80% of the sequences. Compared with that in the pure plantation, the relative abundance of Glomus was higher in the mixed plantation. Glomus, Diversispora and Paraglomus accounted for more than 85% of the sequences in the soil samples. The relative abundances of Diversispora and an unidentified genus of Glomeromycetes were higher and lower in the pure plantation, respectively. The Root_P samples (the roots in the pure plantation) had the highest number of unique OTUs (operational taxonomic units), which belonged mainly to an unidentified genus of Glomeromycetes, Paraglomus, Glomus and Acaulospora. The number of unique OTUs detected in the soil was lower than that in the roots. In both the root and soil samples, the forest type did not have a significant effect on AM fungal diversity, but the Sobs value and the Shannon, Chao1 and Ace indices of AM fungi in the roots were significantly higher than those in the soil.
Mixed forest management had little effect on the AM fungal community of Juglans mandshurica roots and significantly changed the community composition of the soil AM fungi, but not the diversity.
Rare cold-inducible 2 (RCI2) genes from alfalfa (Medicago sativa L.) are part of a multigene family whose members respond to a variety of abiotic stresses by regulating ion homeostasis and ...stabilizing membranes. In this study, salt, alkali, and ABA treatments were used to induce MsRCI2D and MsRCI2E expression in alfalfa, but the response time and the expression intensity of the MsRCI2D,-E genes were different under specific treatments. The expression intensity of the MsRCI2D gene was the highest in salt- and alkali-stressed leaves, while the MsRCI2E gene more rapidly responded to salt and ABA treatment. In addition to differences in gene expression, MsRCI2D and MsRCI2E differ in their subcellular localization. Akin to MtRCI2D from Medicago truncatula, MsRCI2D is also localized in the cell membrane, while MsRCI2E is different from MtRCI2E, localized in the cell membrane and the inner membrane. This difference might be related to an extra 20 amino acids in the C-terminal tail of MsRCI2E. We investigated the function of MsRCI2D and MsRCI2E proteins in alfalfa by generating transgenic alfalfa chimeras. Compared with the MsRCI2E-overexpressing chimera, under high-salinity stress (200 mmol·L−1 NaCl), the MsRCI2D-overexpressing chimera exhibited a better phenotype, manifested as a higher chlorophyll content and a lower MDA content. After salt treatment, the enzyme activities of SOD, POD, CAT, and GR in MsRCI2D- and -E-overexpressing roots were significantly higher than those in the control. In addition, after salt stress, the Na+ content in MsRCI2D- and -E-transformed roots was lower than that in the control; K+ was higher than that in the control; and the Na+/K+ ratio was lower than that in the control. Correspondingly, H+-ATPase, SOS1, and NHX1 genes were significantly up-regulated, and the HKT gene was significantly down-regulated after 6 h of salt treatment. MsRCI2D was also found to regulate the expression of the MsRCI2B and MsRCI2E genes, and the MsRCI2E gene could alter the expression of the MsRCI2A, MsRCI2B, and MsRCI2D genes. MsRCI2D- and -E-overexpressing alfalfa was found to have higher salt tolerance, manifested as improved activity of antioxidant enzymes, reduced content of reactive oxygen species, and sustained Na+ and K+ ion balance by regulating the expression of the H+-ATPase, SOS1, NHX1, HKT, and MsRCI2 genes.
The utilization of symbiosis with beneficial microorganisms has considerable potential for increasing growth and resistance under abiotic stress. The endophytic root fungus Piriformospora indica has ...been shown to improve plant growth under salt and drought stress in diverse plant species, while there have been few reports of the interaction of P. indica with soybean under salt stress. In this study, the symbiotic system of P. indica and soybean (Glycine max L.) was established, and the effect of P. indica on soybean growth and salt tolerance was investigated. The colonized and non-colonized soybeans were subjected to salt stress (200 mmol/L NaCl), and the impairments in chlorophyll and increasing relative conductivity that can be caused by salt stress were alleviated in the P. indica-colonized plants. The accumulation of malondialdehyde (MDA), hydrogen peroxide (H2O2), and superoxide anion (O2−) were lower than that in non-colonized plants under salt treatment, whereas the activities of antioxidant enzymes were significantly increased by P. indica colonization, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and glutathione reductase (GR). Importantly, without salt treatment, the Na+ concentration was lower, and the K+ concentration was higher in the roots compared with non-colonized plants. Differential expressions of ion transporter genes were found in soybean roots after P. indica colonization. The P. indica colonization positively regulated the transcription level of PM H+-ATPase, SOS1, and SOS2. The study shows that P. indica enhances the growth and salt tolerance of soybean, providing a strategy for the agricultural production of soybean plants in saline-alkali soils.
The orientation of water molecules is a key requirement for the fast transport of water in nanotubes. It has been accepted that the flip of the water chain follows a concerted mechanism, which has ...led to the view that bidirectional water flux in nanotubes can be transformed into unidirectional transport when the orientation of water molecules is maintained in long nanotubes under the external field. In this Letter, on the basis of molecular dynamics simulations and first-principles calculations, we confirmed that the flip of the water chain is a step-by-step process, which is different from the perceived concerted mechanism. Further analysis indicated that without an external field, it needed more than 20 water molecules to maintain the unidirectional single-file water flow in a carbon nanotube at a duration time of seconds. Considering that the thickness of the cell membrane (normally 5-10 nm) is larger than the length threshold of the unidirectional water wire, this study suggested that it may not require the external field to maintain the unidirectional flow in the water channel at the macroscopic time scale.
This article provides a systematic way to examine the impact of the innovative knowledge of customers on their recommendation intentions from firm design perspective and investigates the moderating ...effects of guidance methods and design materials provided combining different aspects of cognitive fit, media richness, and sticky information theories. We use the EQXIU platform, conduct two experiments, and find that there are significant differences between the novice customers and expert customers in their recommendation intentions. Experts are more prone to no-template materials, whereas novices are more inclined to use modules and templates. Therefore, to inspire innovation, firms should offer personalized opportunities based on customers’ knowledge levels to enhance their experience. Firms should also design the innovative activities taking into consideration the knowledge levels of their customers. At last, limitations of this study and directions for further research are discussed.
With the increasing requirements for computing in modern society, Multi-access Edge Computing (MEC) has received widespread attention for meeting low-latency. In MEC network, mobile devices can ...offload computing-intensive tasks to edge servers for computing. Wireless Power Transmission (WPT) provides initial energy for mobile devices, and the tasks of mobile devices consume energy when they are locally calculated or completely offloaded. The combination of the two technologies forms the Wireless Powered Mobile Edge Computing (WP-MEC) network. In this article, considering the impact of WPT transmission time <inline-formula> <tex-math notation="LaTeX">\tau _{0} </tex-math></inline-formula>, we study the offloading and scheduling of tasks for multiple mobile devices in the WP-MEC network, which is an NP-hard problem. We formulate this scheduling problem to minimize the time delay under the constraint of WPT transmission energy. We regard our problem studied in this paper as a multidimensional knapsack problem (MKP). The difference is that the knapsack capacity in MKP is limited, while in our problem, the knapsack that one item can choose is limited. Therefore, we improve the Artificial Fish Swarm Algorithm (AFSA) and propose Computation Scheduling Based on the Artificial Fish Swarm Algorithm (CS-AFSA) to find the optimal scheduling. We encode a scheduling scheme as an artificial fish and regard the delay corresponding to the scheduling as the optimization object. The optimal artificial fish can be gradually approached and determined through the swarm, follow and prey behavior of artificial fish. The optimal artificial fish is the optimal scheduling scheme. More importantly, based on the original behavior of AFSA, we also improve the scheme that does not meet the WPT energy constraint, including the modification of infeasible artificial fish and insufficient artificial fish. Besides, we also consider how to find the best WPT transmission time <inline-formula> <tex-math notation="LaTeX">\tau _{0} </tex-math></inline-formula>. Finally, we perform data simulation on the proposed algorithm.
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