Carbon quantum dots (CDs) have inspired vast interest because of their excellent photoluminescence (PL) performances and their promising applications in optoelectronic, biomedical, and sensing ...fields. The development of effective approaches for the large‐scale production of CDs may greatly promote the further advancement of their practical applications. In this Minireview, the newly emerging methods for the large‐scale production of CDs are summarized, such as microwave, ultrasonic, plasma, magnetic hyperthermia, and microfluidic techniques. The use of the available strategies for constructing CD/polymer composites with intriguing solid‐state PL is then described. Particularly, the multiple roles of CDs are emphasized, including as fillers, monomers, and initiators. Moreover, typical applications of CD/polymer composites in light‐emitting diodes, fluorescent printing, and biomedicine are outlined. Finally, we discuss current problems and speculate on their future development.
The latest developments in the large‐scale production of carbon quantum dots by using microwave, ultrasonic, plasma, magnetic hyperthermia, and microfluidic techniques are outlined. The synthetic methods for generating carbon dot/polymer composites are summarized, whereby the carbon quantum dots can serve as fillers, monomers, or initiators. Promising applications, current challenges, and future perspectives are also highlighted and discussed.
Toll-like receptors (TLRs) are important initiators in native immune responses to microbial infections. TLR4 is up-regulated in response to H.pylori infection in gastric epithelial cells. However, ...the regulatory mechanisms for the expression of TLR4 in H.pylori infection have not been clearly defined. The aims of this study are to present the evidence that microRNA let-7b directly regulates TLR4 expression in human gastric epithelial cells, and subsequently influences the activation of NF-κB and the expression of the downstream genes in H.pylori infection.
The expression of let-7b was determined in gastric mucosa specimens and in two gastric epithelial cell lines using quantitative RT-PCR. The expression of TLR4 was determined by immunohistochemistry staining and RT-PCR. The potential target of let-7b was identified by luciferase reporter assay and Western blot. Let-7b mimics and inhibitors were used to examine the effects of let-7b on NF-κB activity. The expression of the downstream genes of NF-κB was also determined in cells infected with H.pylori 26695.
Let-7b was significantly decreased in gastric mucosa specimens and in gastric epithelial cell lines (AGS, GES-1) infected with H.pylori 26695 (cagA+). Let-7b was complementary to the 3'-UTR of TLR4 mRNA and regulated TLR4 expression via post-transcriptional suppression in gastric epithelium. Infection of H.pylori induced the expression of TLR4 and activated NF-κB in AGS and GES-1 cells. Overexpression of let-7b by mimics downregulated TLR4, and subsequently attenuated NF-κB, MyD88, NF-κB1/p50, RelA/p65. The expression of IL-8, COX-2 and CyclinD1 was inhibited in H.pylori infected cells with let-7b overexpression. Both TAK-242 (TLR4 inhibitor) and SN50 (NF-κB inhibitor) significantly inhibited the H.pylori induced downregulation of let-7b.
Let-7b targets at TLR4 mRNA, and regulates the activation of NF-κB and the expression of the downstream genes related to the inflammation and immune responses in H.pylori infection.
Genome size variation is of fundamental biological importance and has been a longstanding puzzle in evolutionary biology. Several hypotheses for genome size evolution including neutral, maladaptive, ...and adaptive models have been proposed, but the relative importance of these models remains controversial. Primulina is a genus that is highly diversified in the Karst region of southern China, where genome size variation and the underlying evolutionary mechanisms are poorly understood. We reconstructed the phylogeny of Primulina using DNA sequences for 104 species and determined the genome sizes of 101 species. We examined the phylogenetic signal in genome size variation, and tested the fit to different evolutionary models and for correlations with variation in latitude and specific leaf area (SLA). The results showed that genome size, SLA and latitudinal variation all displayed strong phylogenetic signals, but were best explained by different evolutionary models. Furthermore, significant positive relationships were detected between genome size and SLA and between genome size and latitude. Our study is the first to investigate genome size evolution on such a comprehensive scale and in the Karst region flora. We conclude that genome size in Primulina is phylogenetically conserved but its variation among species is a combined outcome of both neutral and adaptive evolution.
Protein ubiquitination regulates almost every process in eukaryotic cells. The study of the many enzymes involved in the ubiquitination system and the development of ubiquitination-associated ...therapeutics are important areas of current research. Synthetic tools such as ubiquitin-based chemical probes have been making an increasing contribution to deciphering various biochemical components involved in ubiquitin conjugation, recruitment, signaling, and deconjugation. In the present minireview, we summarize the progress of ubiquitin-based chemical probes with an emphasis on their various structures and chemical synthesis. We discuss the utility of the ubiquitin-based chemical probes for discovering and profiling ubiquitin-dependent signaling systems, as well as the monitoring and visualization of ubiquitin-related enzymatic machinery. We also show how the probes can serve to elucidate the molecular mechanism of recognition and catalysis. Collectively, the development and application of ubiquitin-based chemical probes emphasizes the importance and utility of chemical protein synthesis in modern chemical biology.
This article reviews the design, synthesis, and application of different classes of Ub-based chemical probes.
Impatiens L. is one of the largest angiosperm genera, containing over 1000 species, and is notorious for its taxonomic difficulty. Here, we present, to our knowledge, the most comprehensive ...phylogenetic analysis of the genus to date based on a total evidence approach. Fortyâsix morphological characters, mainly obtained from our own investigations, are combined with sequence data from three genetic regions, including nuclear ribosomal ITS and plastid atpBârbcL and trnLâF. We include 150 Impatiens species representing all clades recovered by previous phylogenetic analyses as well as three outgroups. Maximumâparsimony and Bayesian inference methods were used to infer phylogenetic relationships. Our analyses concur with previous studies, but in most cases provide stronger support. Impatiens splits into two major clades. For the first time, we report that species with threeâcolpate pollen and four carpels form a monophyletic group (clade I). Within clade II, seven wellâsupported subclades are recognized. Within this phylogenetic framework, character evolution is reconstructed, and diagnostic morphological characters for different clades and subclades are identified and discussed. Based on both morphological and molecular evidence, a new classification outline is presented, in which Impatiens is divided into two subgenera, subgen. Clavicarpa and subgen. Impatiens; the latter is further subdivided into seven sections.
Stress corrosion cracking (SCC) behavior of AZ31B Magnesium (Mg) alloy with and without Laser Shock Peening (LSP) was studied using slow strain rate tension (SSRT) method in a simulated body fluid ...(SBF) at 36.5±0.5°C. The effects of two-sided simultaneous LSP on microstructure, residual stress, surface roughness and electrochemical property of AZ31B samples were investigated by using optical microscopy, X-ray diffraction (XRD) method, true color material confocal microscopy, transmission electron microscopy (TEM) and electrochemical polarization experiment. The experimental results show that based on the optimal laser processing parameters, surface nanocrystallization could be induced in the AZ31B surface layer. Comparing with the original samples, the corrosion potential increased 131mV, the corrosion current density decreased by 85.4% and the SCC susceptibility index (ISCC) decreased by 47.5% after LSP. Based on the experimental observations, the improvement mechanism of SCC resistance for AZ31B with LSP was also analysed and revealed.
•Nano-grains can be formed in AZ31B by two-sided simultaneous laser shock peening.•LSP induces symmetric compressive residual stress on both sides of 4mm thick AZ31B.•Corrosion potential of LSP sample increased 131mV compared to original sample.•Corrosion current density of LSP sample reduced by 85.4% compared to original sample.•SCC susceptibility index of LSP sample reduced by 47.5% compared to original sample.
Herein, we explore how OH groups on Pt/γ‐AlOOH and Pt/γ‐Al2O3 catalysts affect CO2 hydrogenation with H2 at temperatures from 250°C to 400°C. OH groups are abundant on γ‐AlOOH, but rare at ...Pt‐(γ‐AlOOH) interface which is the most favorable site for CO2 conversion on Pt/γ‐AlOOH. This makes CO2 hydrogenation on Pt/γ‐AlOOH form CO weakly bonding to γ‐AlOOH, which prefers to desorption from Pt/γ‐AlOOH rather than further conversion, thus enhancing CO production on Pt/γ‐AlOOH. Different from Pt/γ‐AlOOH, OH groups are abundant at Pt‐(γ‐Al2O3) interface which is the most favorable site for CO2 conversion on Pt/γ‐Al2O3. This promotes CO2 hydrogenation on Pt/γ‐Al2O3 to form CO strongly bonding to Pt, which prefers to further hydrogenation to CH4, and thereby increases CH4 selectivity on Pt/γ‐Al2O3. Therefore, the OH groups at metal‐support interface are crucial factor influencing product distribution, and must be considered seriously when fabricating catalysts.
Cartilage injury and pathological degeneration are reported in millions of patients globally. Cartilages such as articular hyaline cartilage are characterized by poor self-regeneration ability due to ...lack of vascular tissue. Current treatment methods adopt foreign cartilage analogue implants or microfracture surgery to accelerate tissue repair and regeneration. These methods are invasive and are associated with the formation of fibrocartilage, which warrants further exploration of new cartilage repair materials. The present study aims to develop an injectable modified gelatin hydrogel.
The hydrogel effectively adsorbed proteoglycans secreted by chondrocytes adjacent to the cartilage tissue in situ, and rapidly formed suitable chondrocyte survival microenvironment modified by ε-poly-L-lysine (EPL). Besides, dynamic covalent bonds were introduced between glucose and phenylboronic acids (PBA). These bonds formed reversible covalent interactions between the cis-diol groups on polyols and the ionic boronate state of PBA. PBA-modified hydrogel induced significant stress relaxation, which improved chondrocyte viability and cartilage differentiation of stem cells. Further, we explored the ability of these hydrogels to promote chondrocyte viability and cartilage differentiation of stem cells through chemical and mechanical modifications.
In vivo and in vitro results demonstrated that the hydrogels exhibited efficient biocompatibility. EPL and PBA modified GelMA hydrogel (Gel-EPL/B) showed stronger activity on chondrocytes compared to the GelMA control group. The Gel-EPL/B group induced the secretion of more extracellular matrix and improved the chondrogenic differentiation potential of stem cells. Finally, thus hydrogel promoted the tissue repair of cartilage defects.
Modified hydrogel is effective in cartilage tissue repair.
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