Hydrogen‐bonded organic frameworks (HOFs) possess various merits, such as high porosity, tunable structure, facile modification, and ready regeneration. These properties have yet to be explored in ...the context of new functional HOF materials. The facile and inexpensive electrophoretic deposition (EPD) method applied in this study generated a transparent HOF film at room temperature in just 2 min and is applicable to other HOFs. The resulting film exhibited reversible electrochromism with the advantage of long cycle life (>500 cycles). More strikingly, this all‐organic film could be readily regenerated (through rinsing with DMF and redeposition) and showed tunable electrochromic behavior (through low‐cost postsynthetic modification) with the ability to undergo successive color changes, which is difficult to achieve with conventional electrochromic materials. An electrochromic device was manufactured to further demonstrate the application potential of the film.
Facile and efficient electrophoretic deposition was used to prepare an electrochromic hydrogen‐bonded organic framework film (see picture), which exhibited reversible electrochromism with the advantages of long cycle life, ready regeneration, and tunable electrochromic behavior. An electrochromic device was manufactured with the film to further demonstrate its application potential.
Taylor series is accessible to all students and it is a useful mathematical tool to nonlinear equations. This paper shows it is extremely simple to solve approximately the well-known Lane–Emden ...equation.
Electrochromic technology offers exciting opportunities for smart applications such as energy‐saving and interactive systems. However, achieving dual‐band regulation together with the multicolor ...function is still an unmet challenge for electrochromic devices. Herein, an ingenious electrochromic strategy based on reversible manganese oxide (MnO2) electrodeposition, different from traditional ion intercalation/deintercalation‐type electrochromic materials is proposed. Such a deposition/dissolution‐based MnO2 brings an intriguing electrochromic feature of dual‐band regulation for the ultraviolet (UV) and visible lights with high optical modulation (93.2% and 93.6% at 400 and 550 nm, respectively) and remarkable optical memory. Moreover, a demonstrative smart window assembled by MnO2 and Cu electrodes delivers the electrochromic properties of effective dual‐band regulation accompanied by multicolor changes (transparent, yellow, and brown). The robust redox deposition/dissolution process endows the MnO2‐based electrochromic device with excellent rate capability and an areal capacity of 570 mAh m−2 at 0.1 mA cm−2. It is believed that the metal oxide‐based reversible electrodeposition strategy would be an attractive and promising electrochromic technology and provide a train of thought for the development of multifunctional electrochromic devices and applications.
A novel electrochromic strategy based on reversible manganese oxide (MnO2) electrodeposition is demonstrated, in which the robust deposition/dissolution process endows the MnO2‐based device with selective dual‐band regulation in ultraviolet–visible regions, remarkable optical memory, multicolor changes (transparent, yellow, and brown), in addition to high rate capability and superior energy storage capacity.
Index modulation concept has attracted considerable research interest in the past few years. As a realization of index modulation in the frequency domain, orthogonal frequency division multiplexing ...with index modulation (OFDM-IM) has recently been proposed, which conveys information bits through both the subcarrier activation patterns and the amplitude phase modulation constellation points. This paper proposes two enhanced OFDM-IM schemes aimed at achieving higher spectral efficiency and diversity gain, respectively. The first one, termed OFDM with hybrid in-phase/quadrature index modulation (OFDM-HIQ-IM), explores the I- and Q- dimensions jointly for index modulation, allowing transmission of more index modulation bits in each subcarrier group. The second one, termed linear constellation precoded OFDM-IQ-IM (LP-OFDM-IQ-IM), spreads information symbols across two adjacent active subcarriers through linear constellation precoding to harvest additional diversity gain. By maximizing the minimum squared Euclidean distance, two different realizations of LP-OFDM-IQ-IM are derived, which leads to a rotated and a diamond-shaped constellation, respectively. The proposed OFDM-HIQ-IM and LP-OFDM-IQ-IM, as revealed by both theoretical analyses and computer simulations, enable low-complexity detection and exhibit superior error rate performance over the existing OFDM-IM schemes.
NOMA is a promising radio access technique for next-generation wireless networks. In this article, we investigate the NOMA-based cooperative relay network. We begin with an introduction of the ...existing relay-assisted NOMA systems by classifying them into three categories: uplink, downlink, and composite architectures. Then we discuss their principles and key features, and provide a comprehensive comparison from the perspective of spectral efficiency, energy efficiency, and total transmit power. A novel strategy called hybrid power allocation is further discussed for the composite architecture, which can reduce the computational complexity and signaling overhead at the expense of marginal sum rate degradation. Finally, major challenges, opportunities, and future research trends for the design of NOMA-based cooperative relay systems with other techniques are also highlighted to provide insights for researchers in this field.
N
-methyladenosine (m6A) RNA methylation contributes to the cancer stem cell (CSC) phenotype through regulating gene expression. YTHDF2, an m6A reader, was shown to be associated with hepatocellular ...carcinoma (HCC) patient prognosis. However, the effect of YTHDF2 on liver CSC and cancer metastasis and the molecular mechanism of this effect have not been documented. Here, we show that YTHDF2 expression is negatively correlated with HCC patient survival in both data from the Cancer Genome Atlas (TCGA) database and clinical data from our center. By detecting CD133
cells and carrying out sphere culture assays, we found that knockdown of YTHDF2 led to impaired stemness in Hep3B and Huh7 cells. In contrast, overexpression of YTHDF2 increased the CSC phenotype. Mechanistically, the knockdown and overexpression of YTHDF2 in liver cancer cells resulted in decreased and increased m6A levels in the 5'-untranslated region (UTR) of OCT4 mRNA, respectively, leading to decreased and increased OCT4 protein expression, respectively. A luciferase activity assay showed that mutation of the corresponding m6A methylation sequence in the 5'-UTR of OCT4 mRNA caused significantly decreased gene expression, suggesting a role for YTHDF2-dependent m6A methylation in protein translation. Polysome profiling results also indicated the knockdown and overexpression of YTHDF2 could decrease and increase OCT4 translation, respectively. In particular, overexpression of OCT4 rescued the impaired stemness caused by YTHDF2 depletion, which confirmed the effect of YTHDF2 on CSC phenotype is dependent on OCT4. In vivo, the loss of YTHDF2 reduced tumor burden and inhibited lung metastasis following orthotopic transplantation in nude mice. Last, we demonstrated that YTHDF2 expression is positively correlated with OCT4 expression and m6A levels in the 5'-UTR of OCT4 mRNA in clinical HCC specimens. In conclusion, YTHDF2 promotes the CSC liver phenotype and cancer metastasis by modulating the m6A methylation of OCT4 mRNA.
•The Hamilton principle is used to derive the governing equation for transverse vibration of a reinforced concrete pillar.•A Boussinesq-like equation is obtained and its resonance-like and solitary ...solutions are discussed.•A fractal Boussinesq equation is discussed for vibration design by taking into account the porous structure of concrete.•The morphology of a travelling wave can be effectively controlled by the fractal dimensions of fractal concrete.
An approximate Hamilton principle is established for the transverse vibration of a reinforced concrete pillar by considering the dissipation energy, and a generalized Boussinesq equation is obtained. The exp-function method is adopted to solve the equation, and its solution properties are discussed and elucidated, including solitary solution, blowup solution, and discontinuous solution. In order to study the effect of a porous structure on the vibration property, fractal calculus is used to derive the fractal Boussinesq equation, and a fractal variational principle is also established. The fractal model confers many attractive properties, which can not be revealed by the traditional protocol. The effect of the nanofiber-reinforced concrete structure on its wave morphology is discussed and illustrated. A blowup solution can be converted into a flat solution by adjusting the value of the fractal derivative order. The paper sheds new light on the design of reinforced concrete pillars to avoid vibration damage.
The molecular mechanism underlying brain regeneration in vertebrates remains elusive. We performed spatial enhanced resolution omics sequencing (Stereo-seq) to capture spatially resolved single-cell ...transcriptomes of axolotl telencephalon sections during development and regeneration. Annotated cell types exhibited distinct spatial distribution, molecular features, and functions. We identified an injury-induced ependymoglial cell cluster at the wound site as a progenitor cell population for the potential replenishment of lost neurons, through a cell state transition process resembling neurogenesis during development. Transcriptome comparisons indicated that these induced cells may originate from local resident ependymoglial cells. We further uncovered spatially defined neurons at the lesion site that may regress to an immature neuron–like state. Our work establishes spatial transcriptome profiles of an anamniote tetrapod brain and decodes potential neurogenesis from ependymoglial cells for development and regeneration, thus providing mechanistic insights into vertebrate brain regeneration.
Trade-offs in brain development
Salamander brains share some, but not all, structures with the mammalian brain. They also have greater capacity to regenerate in response to damage. Three groups now come together with single-cell transcriptomics analyses that set the salamander brain in evolutionary context (see the Perspective by Faltine-Gonzalez and Kebschull). By comparing salamander brains with those of lizard, turtle, and mouse, Woych
et al
. track the evolutionary innovations that gave rise to the mammalian six-layered neocortex, which salamanders do not have. Lust
et al
. take a close look at why the axolotl brain is so much more capable of regeneration than is the mammalian brain. Finally, Wei
et al
. compare the developmental and regenerative processes in the axolotl brain. —PJH
Developmental and regenerative processes in the axolotl brain are revealed by single-cell analyses.
INTRODUCTION
Brain regeneration requires the coordination of complex responses in a time- and region-specific manner. Identifying the cell types and molecules involved in this process would advance our understanding of brain regeneration and provide potential targets for regenerative medicine research. However, progress in this field has been hampered by the limited regeneration capacity of the mammalian brain and an incomplete mechanistic understanding of the regeneration process at both the cellular and molecular levels. Axolotls (
Ambystoma mexicanum
) can regenerate damaged appendages and multiple internal organs, including the brain. Therefore, axolotls may serve as a model for studying brain regeneration.
RATIONALE
If we are to understand the mechanism of brain regeneration, we need research tools that can achieve large-scale data acquisition and analyses to simultaneously decode complex cellular and molecular responses. It also seemed to us that a comparison between brain regeneration and developmental processes would help to provide new insights into the nature of brain regeneration. Accordingly, we removed a small portion of the lateral pallium region of the axolotl left telencephalon and collected tissue samples at multiple stages during regeneration. In parallel, we collected tissue samples of the axolotl telencephalon at multiple developmental stages. We then used high-definition and large-field Stereo-seq (spatial enhanced resolution omics sequencing) technology to generate spatial transcriptomic data from sections that covered both hemispheres of the axolotl telencephalon at single-cell resolution. Analyses of cell type annotation, cell spatial organization, gene activity dynamics, and cell state transition were performed for a mechanistic investigation of injury-induced regeneration compared to these cell attributes during development.
RESULTS
With the use of Stereo-seq, we generated a group of spatial transcriptomic data of telencephalon sections that covered six developmental and seven injury-induced regenerative stages. The data at single-cell resolution enabled us to identify 33 cell types present during development and 28 cell types involved in regeneration, including different types of excitatory and inhibitory neurons, and several ependymoglial cell subtypes. For development, our data revealed a primitive type of ependymoglial cells that may give rise to three subgroups of adult ependymoglial cells localized in separate areas of the ventricular zone, with different molecular features and potentially different functions. For regeneration, we discovered a subpopulation of ependymoglial cells that may originate from local resident ependymoglial cells activated by injury. This population of progenitor cells may then proliferate to cover the wound area and subsequently replenish lost neurons through a state transition to intermediate progenitors, immature neurons, and eventually mature neurons. When comparing cellular and molecular dynamics of the axolotl telencephalon between development and regeneration, we found that injury-induced ependymoglial cells were similar to developmental-specific ependymoglial cells in terms of their transcriptome state. We also observed that regeneration of the axolotl telencephalon exhibited neurogenesis patterns similar to those seen in development in molecular cascades and the potential cell lineage transition, which suggests that brain regeneration partially recapitulates the development process.
CONCLUSION
Our spatial transcriptomic data highlight the cellular and molecular features of the axolotl telencephalon during development and injury-induced regeneration. Further characterization of the activation and functional regulation of ependymoglial cells may yield insights for improving the regenerative capability of mammalian brains. Our single-cell spatial transcriptome of the axolotl telencephalon, a tetrapod vertebrate, also provides data useful for further research in developmental, regenerative, and evolutionary brain biology. All data are accessible in an interactive database (
https://db.cngb.org/stomics/artista
).
Development and regeneration of axolotl telencephalon.
The spatially resolved single-cell transcriptome of the adult axolotl telencephalon as determined by Stereo-seq analyses (left). Upon brain injury in the highlighted lateral pallium region of the left hemisphere, a neural progenitor subpopulation at the wound site was rapidly induced and subsequently replenished lost neurons (bottom right) through a process that partially resembles neurogenesis during development (top right).
CREDIT: YUNZHI YANG, BGI
Developing a noncontact ratiometric luminescent temperature sensor with high sensitivity, widely available emission range, and reliable performance is a challenge in materials science. Herein, we ...demonstrated that this goal can be achieved by fabricating a lanthanide-functionalized hydrogen-bonded organic framework film (named the Eu@HOF-TCBP film). The unbonded carboxylic groups that existed in the structure not only enable lanthanide ions to bind with the framework for bringing dual emission but also allow for preparing a hydrogen-bonded organic framework (HOF) film through the facile electrophoretic deposition. The obtained film exhibits ratiometric temperature sensing performance in the range of 297–377 K with a maximum relative sensitivity of 5.787% K–1 and shows repeated use without sensitivity loss. Moreover, the material can be easily recycled and refabricated with consistent performance, demonstrating its unique merits of easy recyclability and regeneration as an HOF material. We believe that the reported strategies for preparing a dual-emitting HOF and fabricating a thin film will open a window for HOF applications.
The laboratory axolotl (Ambystoma mexicanum) is widely used in biological research. Recent advancements in genetic and molecular toolkits are greatly accelerating the work using axolotl, especially ...in the area of tissue regeneration. At this juncture, there is a critical need to establish gene and transgenic nomenclature to ensure uniformity in axolotl research. Here, we propose guidelines for genetic nomenclature when working with the axolotl.
Key Findings
Axolotl has become the favored model organism for tetrapod tissue regeneration. We propose here gene and transgenic nomenclature guidelines that will allow researchers to communicate it more efficiently.