The homeodomain transcription factor WUSCHEL (WUS) defines the shoot stem cell niche, but the mechanisms underlying the establishment of WUS expression remain unclear. Here, we show that cytokinin ...signaling precedes WUS expression in leaf axils and activates WUS expression de novo in the leaf axil to promote axillary meristem initiation. Furthermore, type-B Arabidopsis response regulator proteins, which are transcriptional activators in the cytokinin signaling pathway, directly bind to the WUS promoter and activate its expression. Finally, we show that cytokinin activation of WUS in the leaf axil correlates with increased histone acetylation and methylation markers associated with transcriptional activation, supporting the fact that WUS expression requires a permissive epigenetic environment to restrict it to highly defined meristematic tissues. Taken together, these findings explain how cytokinin regulates axillary meristem initiation and establish a mechanistic framework for the postembryonic establishment of the shoot stem cell niche.
In this paper, systematic neural network modeling techniques are presented for microwave modeling and design using the concept of inverse modeling where the inputs to the inverse model are electrical ...parameters and outputs are geometrical parameters. Training the neural network inverse model directly may become difficult due to the nonuniqueness of the input-output relationship in the inverse model. We propose a new method to solve such a problem by detecting multivalued solutions in training data. The data containing multivalued solutions are divided into groups according to derivative information using a neural network forward model such that individual groups do not have the problem of multivalued solutions. Multiple inverse models are built based on divided data groups, and are then combined to form a complete model. A comprehensive modeling methodology is proposed, which includes direct inverse modeling, segmentation, derivative division, and model combining techniques. The methodology is applied to waveguide filter modeling and more accurate results are achieved compared to the direct neural network inverse modeling method. Full electromagnetic simulation and measurement results of Ku-band circular waveguide dual-mode pseudoelliptic bandpass filters are presented to demonstrate the efficiency of the proposed neural network inverse modeling methodology.
Recently, strong polymer‐based hydrogels have been intensively investigated. However, the development of tough protein hydrogels with controlled degradation for bone regeneration has rarely been ...reported. Here, regenerated silk fibroin/gelatin (RSF/G) hydrogels with both strength and controlled degradation are prepared via physically and chemically double‐crosslinked networks. As a representative example, the 9%RSF/3%G hydrogel shows approximately 80% elongation and a compressive and tensile modulus of up to 0.25 and 0.21 MPa, respectively. It also shows a degradation rate that can be adjusted to approximately three months in vivo, a value between that of the rapidly degrading gelatin hydrogel and the slowly degrading RSF hydrogel. The 9%RSF/3%G hydrogel has good biocompatibility and promotes the proliferation and differentiation of bone marrow–derived stem cells compared with the control and pure RSF hydrogels. At 12 weeks after implantation of the gel in a calvarial defect, micro‐computed tomography shows greater bone volume and bone mineral density in the 9%RSF/3%G group. More importantly, histology reveals more mineralization and enhancements in the quality and rate of bone regeneration with less of a tissue response in the 9%RSF/3%G group. These results indicate the promising potential of this tough protein hydrogel with controlled degradation for bone regeneration applications.
A novel facile strategy is developed to fabricate strong and tough hydrogels with controlled degradation by immersing an enzymatically crosslinked regenerated silk fibroin/gelatin (RSF/G) hydrogel in a salt solution, forming a double‐crosslinked network. The resulting 9%RSF/3%G hydrogel shows high strength, good biocompatibility, a suitable degradation rate, and capacity for promoting osteogenic differentiation and bone regeneration.
Herein, we observed near-infrared electrochemiluminescence (NIR ECL) emission from tetraphenylethylene nanocrystals (TPE NCs), which exhibit high ECL efficiency and excellent biocompatibility ...compared with the current NIR ECL emitters (such as semiconductor quantum dots and metal nanoclusters). The strong ECL signal of TPE NCs originates from the aggregation-induced enhanced ECL emission
improvement of the efficiency of electron hole recombination and suppression of the nonradiative transition. Impressively, the TPE NCs exhibit an enormous red-shifted ECL emission (678 nm) relative to the blue-light photoluminescence (PL) emission (440 nm). Compared to fluorescence imaging which is limited by photobleaching and autofluorescence, the NIR ECL emission of TPE NCs is highly favorable to diminish background interference over visible light and realize deeper tissue penetration, which expands the ECL emission of organic nanomaterials to the NIR region for broader biological applications.
Chiral Brønsted acid-catalysed asymmetric synthesis has received tremendous interest over the past decades, and numerous efficient synthetic methods have been developed based on this approach. ...However, the use of chiral Brønsted acids in these reactions is mostly limited to the activation of imine and carbonyl moieties, and the direct activation of carbon–carbon triple bonds has so far not been invoked. Here we show that chiral Brønsted acids enable the catalytic asymmetric dearomatization reactions of naphthol-, phenol- and pyrrole-ynamides by the direct activation of alkynes. This method leads to the practical and atom-economic construction of various valuable spirocyclic enones and 2H-pyrroles that bear a chiral quaternary carbon stereocentre in generally good-to-excellent yields with excellent chemo-, regio- and enantioselectivities. The activation mode of chiral Brønsted acid catalysis revealed in this study is expected to be of broad utility in catalytic asymmetric reactions that involve ynamides and the related heteroatom-substituted alkynes.Chiral Brønsted acid catalysis is mostly limited to the activation of imine and carbonyl moieties. Now, by direct activation of alkynes, chiral Brønsted acids have been used to enable the catalytic asymmetric dearomatization of naphthol-, phenol- and pyrrole-ynamides for the construction of various spirocyclic enones and 2H-pyrroles bearing a chiral quaternary carbon stereocentre.
Integrating Internet of Things (IoT) technologies in art design has created new possibilities for artists to create immersive and interactive experiences. However, data collection, analysis, and ...utilization in IoT art installations raise significant security and privacy concerns. Additionally, incorporating differential privacy techniques in IoT art installations poses optimization challenges. This paper explores optimizing differential privacy budgets based on deep learning in IoT art installations. By leveraging deep learning models, privacy budgets can be dynamically allocated to preserve individual privacy while maintaining the aesthetic integrity of the artwork. In light of this, a deep learning-based differential privacy budget optimization strategy for IoT art installations is suggested. This method adaptively distributes various budgets by the iterative change law of parameters. A regularization term is provided to limit the disturbance term to avoid the issue of excessive noise. This stops the neural network from overfitting and also assists in learning the model's salient characteristics. The capacity of the model to generalize is effectively improved by the suggested strategy, according to experiments. The accuracy difference between the model trained with noise and the model trained with original data is less than 0.5% as the number of iterations increases. Therefore, the proposed method can protect the user's privacy, effectively ensure the model's availability, and achieve the balance between privacy and availability. This accuracy ensures that the installation functions as intended and delivers the desired aesthetic impact, enabling artists to convey their artistic message effectively.
Molecular capsules have attracted interest as simple enzyme mimetics and several examples of catalytic transformations in water-soluble metal–ligand based systems have been reported. This is not the ...case for hydrogen-bond based molecular capsules, which in contrast can be employed in organic solvents. We describe herein our investigations of such a system: The resorcin4arene hexamer is one of the largest hydrogen bond-based self-assembled capsules and has been studied intensively due to its ready availability. We present evidence that the capsule acts as a reasonably strong Brønsted acid (pK a approximately 5.5–6). This finding explains the capsule’s high affinity toward tertiary amines that are protonated and therefore encounter cation-π interactions inside the cavity. We were able to translate this finding into a first synthetic application: A highly substrate-selective Wittig reaction. We also report that this property renders the capsule an efficient enzyme-like catalyst for substrate selective diethyl acetal hydrolysis.
The adoption of pest-resistant transgenic plants to reduce yield loss and pesticide utilization has been successful in the past three decades. Recently, transgenic plant expressing double-stranded ...RNA (dsRNA) targeting pest genes emerges as a promising strategy for improving pest resistance in crops. The steroid hormone, 20-hydroxyecdysone (20E), predominately controls insect molting via its nuclear receptor complex, EcR-USP. Here we report that pest resistance is improved in transgenic tobacco plants expressing dsRNA of EcR from the cotton bollworm, Helicoverpa armigera, a serious lepidopteran pest for a variety of crops. When H. armigera larvae were fed with the whole transgenic tobacco plants expressing EcR dsRNA, resistance to H. armigera was significantly improved in transgenic plants. Meanwhile, when H. armigera larvae were fed with leaves of transgenic tobacco plants expressing EcR dsRNA, its EcR mRNA level was dramatically decreased causing molting defects and larval lethality. In addition, the transgenic tobacco plants expressing H. armigera EcR dsRNA were also resistant to another lepidopteran pest, the beet armyworm, Spodoptera exigua, due to the high similarity in the nucleotide sequences of their EcR genes. This study provides additional evidence that transgenic plant expressing dsRNA targeting insect-associated genes is able to improve pest resistance.
The ultra-reliable low latency communications (uRLLC) in the fifth generation mobile communication system aims to support diverse emerging applications with strict requirements of latency and ...reliability. Mobile edge computing (MEC) is considered as a promising solution to reduce the latency of computation-intensive tasks leveraging powerful computing units at short distance. The state-of-art work on task offloading to MEC mainly focuses on the tradeoff between latency and energy consumption, rather than reliability. In this paper, the tradeoff between the latency and reliability in task offloading to MEC is studied. A framework is provided, where user equipment partitions a task into sub-tasks and offloads them to multiple nearby edge nodes (ENs) in sequence. In this framework, we formulate an optimization problem to jointly minimize the latency and offloading failure probability. Since the formulated problem is nonconvex, we design three algorithms based on heuristic search , reformulation linearization technique and semi-definite relaxation , respectively, and solve the problem through optimizing EN candidates selection , offloading ordering and task allocation . Compared with the previous work, the numerical simulation results show that the proposed algorithms strike a good balance between the latency and reliability in uRLLC. Among them, the Heuristic Algorithm achieves the best performance in terms of the latency and reliability with the minimal complexity.
PDF
