Three-dimensional (3D) laser nanoprinting allows maskless manufacturing of diverse nanostructures with nanoscale resolution. However, 3D manufacturing of inorganic nanostructures typically requires ...nanomaterial-polymer composites and is limited by a photopolymerization mechanism, resulting in a reduction of material purity and degradation of intrinsic properties. We developed a polymerization-independent, laser direct writing technique called photoexcitation-induced chemical bonding. Without any additives, the holes excited inside semiconductor quantum dots are transferred to the nanocrystal surface and improve their chemical reactivity, leading to interparticle chemical bonding. As a proof of concept, we printed arbitrary 3D quantum dot architectures at a resolution beyond the diffraction limit. Our strategy will enable the manufacturing of free-form quantum dot optoelectronic devices such as light-emitting devices or photodetectors.
Photoprinting nanoparticles
Nanoparticle assembly often requires tailored selection of the ligands so that they can selectively bond, as with complementary DNA strands. Alternately, they can be linked together at specified locations using photopolymerization to connect ligands at desired places. However, this process adds to the complexity of making the nanoparticles and is limited by the fidelity of the ligand attachment. Liu
et al
. show that light can be used to desorb surface thiolate ligands from cadmium selenide/zinc sulfide core shell quantum dots (see the Perspective by Pan and Talapin). The resulting trapped holes drive bonding between the particles through the remaining surface ligands. The authors reveal photoprinting of arbitrary three-dimensional architectures at a resolution beyond the diffraction limit and for a range of nanocrystals. Printing can be optically selected based on the size and/or bandgap of the quantum dots. —MSL
Photoexcitation-induced chemical bonding enables high-resolution three-dimensional printing of semiconductor quantum dots.
This paper reports the morphology, size and phase control of NiS nanoflowers on a graphene substrate. The growth mechanisms of various building blocks for NiS nanoflowers such as nanosheets, ...nanoflakes, and nanorods are explored under varied experimental conditions. All the obtained NiS nanoflowers were found to be uniformly dispersed on graphene nanosheets, forming a sandwiched nanostructure. When fabricated as an anode material for Li-ion batteries, the graphene supported NiS nanorod-assembled nanoflower shows better cycling performances than pristine NiS and other NiS–graphene composites. It shows a large unprecedented reversible lithium-extraction capacity of 887 mA h g −1 after 60 cycles at 59 mA g −1 and good high-rate capability among NiS-based anodes.
Thirty specimens of built-up closed box sections consisting of two cold-formed steel channels of various cross sections (B92 and B143), lengths (3000, 1500, 450, and 270 mm), and thicknesses (1.2 and ...1.5 mm) were tested subject to concentric and eccentric axial compression. Failure modes were analyzed and load vs. displacement curves were obtained. The test results indicate that the failure modes of long and medium columns subject to concentric axial compression are flexural buckling about the weak axis, whereas that of the short column is excessive local buckling; specimens subject to eccentric axial compression about the strong and weak axes exhibited flexural-torsional buckling and flexural buckling, respectively. Finite element (FE) models were established and verified. Detailed parameter studies were performed to evaluate the accuracy of code equations for a wide range of parameters. The FE analysis results indicate that the concentric axial compression strength of the columns decreased with an increase in the slenderness ratio of column or the web height-to-thickness ratio; increasing the flange width can significantly increase the stability and strength of the column; the eccentric axial compression strength of the column about the weak axis decreased faster than that about the strong axis. Finally, the effectiveness of the design methods, i.e., the effective ratio of width-to-thickness method in the Chinese code, effective width method, direct strength method, and load and resistance factor design in North American specifications to predict the strength of this type of built-up column is evaluated. For the B92 series columns and B143 series column with slenderness ratio of the column greater than 92, it is conservative to use design methods to calculate the concentric axial compression strength of the column. Additionally, it is conservative to use the design methods to calculate the eccentric axial compression strength of the columns.
•Axial compression tests were conducted on built-up closed box section columns consisting of two cold-formed steel channels.•The failure modes of the specimens were analyzed.•FE models of built-up closed box section columns were developed and verified with test results.•A parametric study was performed varying the screw spacing, the slenderness ratio of the columns, etc.•The effectiveness of available design codes to predict the strength of built-up closed box section columns was evaluated.
By combining chaotic system and DNA sequence operations, an image cryptosystem is proposed. To generate sequences with better chaotic characteristics, a new spatiotemporal chaotic system is ...constructed by employing the Logistic-Sine system (LSS) in the coupled map lattice (CML). In the cryptosystem, the original image is firstly diffused through exclusive or with a key image transformed from the constructed spatiotemporal chaotic sequences. Furthermore, DNA deletion and DNA insertion pseudo-operations are used to confuse the DNA-encoded diffused image under the control of the key streams. The encrypted image is obtained after decoding the confused DNA image. Experimental results and performance analysis demonstrate that the proposed image cryptosystem has acceptable speed, good robustness and outperforms some existing image encryption schemes to counteract the recognized attacks.
•LSS-based CML is constructed with better chaotic characteristics.•DNA deletion and DNA insertion are employed to confuse the DNA-encoded image.•The cryptosystem outperforms some image encryption algorithms on some performance.
In
and related species, flagellar brake protein YcgR responds to the elevated intracellular c-di-GMP, decreases the flagellar rotation speed, causes a CCW rotation bias, and regulates bacterial ...swimming. Boehm et al. suggested that c-di-GMP-activated YcgR directly interacted with the motor protein MotA to curb flagellar motor output. Paul et al. proposed that YcgR disrupted the organization of the FliG C-terminal domain to bias the flagellar rotation. The target proteins are controversial, and the role of motor proteins remains unclear in flagellar rotation speed and direction regulation by YcgR. Here we assayed the motor proteins' affinity via a modified FRET biosensor and accessed the role of those key residue via bead assays. We found that YcgR could interact with both MotA and FliG, and the affinities could be enhanced upon c-di-GMP binding. Furthermore, residue D54 of YcgR-N was needed for FliG binding. The mutation of the FliG binding residue D54 or the MotA binding ones, F117 and E232, restored flagellar rotation speed in wild-type cells and cells lacking chemotaxis response regulator CheY that switched the flagellar rotation direction and decreased the CCW ratio in wild-type cells. We propose that c-di-GMP-activated YcgR regulated the flagellar rotation speed and direction via its interaction with motor proteins MotA and FliG. Our work suggest the role of YcgR-motor proteins interaction in bacterial swimming regulation.
The Northeast Plain is the largest maize production area in China, and drip irrigation has recently been proposed to cope with the effects of frequent droughts and to improve water use efficiency ...(WUE). In order to develop an efficient and environmentally friendly irrigation system, drip irrigation experiments were conducted in 2016–2018 incorporating different soil water conservation measures as follows: (1) drip irrigation under plastic film mulch (PI), (2) drip irrigation under biodegradable film mulch (BI), (3) drip irrigation incorporating straw returning (SI), and (4) drip irrigation with the tape buried at a shallow soil depth (OI); with furrow irrigation (FI) used as the control. The results showed that PI and BI gave the highest maize yield, as well as the highest WUE and nitrogen use efficiency (NUE) because of the higher root length density (RLD) and better heat conditions during the vegetative stage. But compared with BI, PI consumed more soil water in the 20–60 and 60–100 cm soil layers, and accelerated the progress of root and leaf senescence due to a larger root system in the top 0–20 cm soil layer and a higher soil temperature during the reproductive stage. SI was effective in improving soil water and nitrate contents, and promoted RLD in deeper soil layers, thereby maintaining higher physiological activity during the reproductive stage. FI resulted in higher nitrate levels in the deep 60–100 cm soil layer, which increased the risk of nitrogen losses by leaching compared with the drip irrigation treatments. RLD in the 0–20 cm soil layer was highly positively correlated with yield, WUE and NUE (P<0.001), but it was negatively correlated with root nitrogen use efficiency (NRE) (P<0.05), and the correlation was weaker in deeper soil layers. We concluded that BI had advantages in water–nitrogen utilization and yield stability response to drought stress, and thus is recommended for environmentally friendly and sustainable maize production in Northeast China.
Biodiesel-derived glycerol is a promising substrate for mixotrophic cultivation of oleaginous microalgae, which can also reduce the cost of microalgal biodiesel. The objective of this study is to ...investigate the potential of using glycerol and glucose as a complex carbon substrate to produce microalgal biomass and biochemical components, such as photosynthetic pigments, lipids, soluble carbohydrates and proteins by Chlorella vulgaris. The results show that C. vulgaris can utilize glycerol as a sole carbon substrate, but its effect is inferior to that of the mixture of glycerol and glucose. The effect of glycerol and glucose could enhance the algal cell growth rate, biomass content and volumetric productivity, and overcome the lower biomass production on glycerol as the sole organic carbon source in mixotrophic culture medium. The utilization of complex organic carbon substrate can stimulate the biosynthesis of lipids and soluble carbohydrates as the raw materials for biodiesel and bioethanol production, and reduce the anabolism of photosynthetic pigments and proteins. This study provides a promising niche for reducing the overall cost of biodiesel and bioethanol production from microalgae as it investigates the by-products of algal biodiesel production and algal cell hydrolysis as possible raw materials (lipids and carbohydrates) and organic carbon substrates (soluble carbohydrates and glycerol) for mixotrophic cultivation of microalgae.
Optimized New Shengmai Powder (ONSMP) is a sophisticated traditional Chinese medicinal formula renowned for bolstering vital energy, optimizing blood circulation, and mitigating fluid retention. ...After years of clinical application, ONSMP has shown a significant impact in improving myocardial injury and cardiac function and has a positive effect on treating heart failure. However, many unknowns exist about the molecular biological mechanisms of how ONSMP exerts its therapeutic effects, which require further research and exploration.
Exploring the potential molecular biological mechanisms by which ONSMP ameliorates cardiomyocyte apoptosis and ferroptosis in ischemic heart failure (IHF).
First, we constructed a rat model of IHF by inducing acute myocardial infarction through surgery and using echocardiography, organ coefficients, markers of heart failure, antioxidant markers, and histopathological examination to assess the effects of ONSMP on cardiomyocyte apoptosis and ferroptosis in IHF rats. Next, we used bioinformatics analysis techniques to analyze the active components, signaling pathways, and core targets of ONSMP and calculated the interactions between core targets and corresponding elements. Finally, we detected the positive expression of apoptosis and ferroptosis markers and core indicators of signaling pathways by immunohistochemistry; detected the mean fluorescence intensity of core indicators of signaling pathways by immunofluorescence; detected the protein expression of signaling pathways and downstream effector molecules by western blotting; and detected the mRNA levels of p53 and downstream effector molecules by quantitative polymerase chain reaction.
ONSMP can activate the Ser83 site of ASK by promoting the phosphorylation of the PI3K/AKT axis, thereby inhibiting the MKK3/6-p38 axis and the MKK4/7-JNK axis signaling to reduce p53 expression, and can also directly target and inhibit the activity of p53, ultimately inhibiting p53-mediated mRNA and protein increases in PUMA, SAT1, PIG3, and TFR1, as well as mRNA and protein decreases in SLC7A11, thereby inhibiting cardiomyocyte apoptosis and ferroptosis, effectively improving cardiac function and ventricular remodeling in IHF rat models.
ONSMP can inhibit cardiomyocyte apoptosis and ferroptosis through the PI3K/AKT/p53 signaling pathway, delaying the development of IHF.
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•Optimized New Shengmai Powder can reduce myocardial injury and improve the cardiac function of ischemic heart failure rats.•Apoptosis and ferroptosis are involved in the anti-myocardial injury effect mediated by Optimized New Shengmai Powder.•Optimized New Shengmai Powder regulates the PI3K/AKT/p53 signaling pathway to inhibit cardiomyocyte apoptosis and ferroptosis, providing a new perspective for the treatment of ischemic heart failure.
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