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.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
AbstractAluminum alloys are being increasingly used in a wide range of construction applications owing to their sound mechanical properties, lightness in weight, strong corrosion resistance, ability ...to be formed into complex and efficient cross-sectional shapes, and natural aesthetics. Aluminum alloys are characterized by a rounded stress–strain response, with no sharply defined yield point. Such behavior can be accurately represented using Ramberg–Osgood-type equations. In the present study, use of a two-stage Ramberg–Osgood model to describe the full-range stress–strain behavior of aluminum alloys is proposed and, following careful analysis of a comprehensive database of aluminum alloy coupon test data assembled from the literature, standardized values or predictive expressions for the required input parameters are derived. The experimental database includes over 700 engineering stress–strain curves obtained from 56 sources and covers five common aluminum alloy grades: 5052-H36, 6061-T6, 6063-T5, 6082-T6, and 7A04-T6. The developed model is shown to be more accurate in predicting the full-range stress–strain response of aluminum alloys than existing expressions, and is suitable for use in the analytical modeling, numerical simulation, and advanced design of aluminum alloy structures.
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.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Despite the dramatic rise in power conversion efficiencies (PCEs) of perovskite solar cells (PeSCs), concerns surrounding the long-term stability as well as the poor reproducibility in the archetypal ...three-dimensional (3D) perovskite, MAPbI3 (MA = CH3NH3), have the potential to derail commercialization. We have reported the fabrication and properties of a series of 2D perovskite compounds (PEI)2(MA) n−1Pb n I3n+1 (n = 3, 5, 7) by incorporating polyethylenimine (PEI) cations within the layered structure. The benefits of using intercalated polymer cations in the multilayered films are multiple: moisture resistance and film quality are greatly enhanced compared to that of their 3D MAPbI3 analogue; charge transport within solar cells can also be improved compared to that of 2D materials using small-molecule bulky ammonium. The moisture-stable nature of the multilayered perovskite materials allow for the simple one-step fabrication of cells with an aperture area of 2.32 cm2 under ambient humidity that have a PCE up to 8.77%. Overall, the 2D perovskite family offers rich multitudes of substituent and crystal structures, defining a promising class of stable and efficient light-absorbing materials.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
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.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
A guest-induced reversible crystal-structure transformation is identified in a new 3D covalent organic framework (COF) by comprehensive analyses using powder X-ray diffraction, organic vapor sorption ...isotherm, and 129Xe NMR spectroscopy. The revolving imine bond in interpenetrating 3D networks is uncovered as the key to the dynamic behavior, the potential applications of which are illustrated by gas separation and heterogeneous catalysis, thus paving the way to the design of stimuli-responsive and multifunctional COF materials.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
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.
Full text
Available for:
IJS, KILJ, NUK, UL, UM, UPUK
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.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
AbstractHigh-strength aluminum alloys are emerging and gaining increasing prominence in structural engineering. The structural behavior and design of 7A04-T6 high-strength aluminum alloy equal-leg ...angle-section columns under axial compression are investigated in this study. Eighteen experiments on extruded high-strength aluminum alloy angle-section columns with various lengths were carried out. Complementary material tests and initial geometric imperfection measurements were also performed. The test setup, procedure, and results, including failure modes, load-carrying capacities, and load–end shortening responses, are fully reported. The test program was followed by a numerical study, where refined finite-element (FE) models were first developed and validated against the test results and then utilized to carry out parametric analyses covering a wide range of cross-section dimensions and column lengths. Finally, the load-carrying capacities obtained from the tests and numerical analyses were used to evaluate the accuracy of existing design provisions in European, Chinese, and American standards for aluminum alloy structures and the direct strength method (DSM). The results show that the existing design methods generally yield good capacity predictions for fixed-ended members failing by flexural buckling, but rather conservative and scattered predictions when failure is by flexural-torsional buckling. Improved resistance predictions were achieved through application of a revised DSM-based approach.
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.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
PDF
