Fluorescence bioimaging in the second near‐infrared spectral region (NIR‐II, 1000–1700 nm) can provide advantages of high spatial resolution and large penetration depth, due to low light scattering. ...However, NIR‐II fluorophores simultaneously possessing high brightness, good stability, and biocompatibility are very rare. Hydrophobic NIR‐II emissive PbS@CdS quantum dots (QDs) are surface‐functionalized, via a silica and amphiphilic polymer (Pluronic F‐127) dual‐layer coating method. The as‐synthesized PbS@CdS@SiO2@F‐127 nanoparticles (NPs) are aqueously dispersible and possess a quantum yield of ≈5.79%, which is much larger than those of most existing NIR‐II fluorophores. Thanks to the dual‐layer protection, PbS@CdS@SiO2@F‐127 NPs show excellent chemical stability in a wide range of pH values. The biocompatibility of PbS@CdS@SiO2@F‐127 NPs is studied, and the results show that the toxicity of the NPs in vivo could be minimal. PbS@CdS@SiO2@F‐127 NPs are then utilized for in vivo and real‐time NIR‐II fluorescence microscopic imaging of mouse brain. The architecture of blood vessels is visualized and the imaging depth reaches 950 µm. Furthermore, in vivo NIR‐II fluorescence imaging of gastrointestinal tract is achieved, by perfusing PbS@CdS@SiO2@F‐127 NPs into mice at a rather low dosage. This work illustrates the potential of ultrastable, biocompatible, and bright NIR‐II QDs in biomedical and clinical applications, which require deep tissue imaging.
NIR‐II emissive PbS@CdS quantum dots are surface‐functionalized with a dual‐layer coating method. The as‐synthesized PbS@CdS@SiO2@F‐127 nanoparticles (NPs) are aqueously dispersible, and possess certain brightness. Chemically stable and biocompatible PbS@CdS@SiO2@F‐127 NPs are utilized for deep tissue (950 µm) in vivo microscopic angiography of the mice brain. Noninvasive and large depth (3–5 mm) gastrointestinal tract imaging with high contrast is achieved.
This paper mainly studies a detection method of dynamic load altering attacks (D‐LAAs) in smart grids. First, communication factors are considered, and a smart grid discrete system model under D‐LAA ...attack is established. Second, for closed‐loop D‐LAAs, an adaptive fading Kalman filter (AFKF) is designed to estimate the states of smart grids with Gaussian noise in real time, and a Euclidean distance ratio detection algorithm based on AFKF is proposed to detect D‐LAAs. Moreover, the proposed detection algorithm can identify D‐LAAs even in the presence of noise in the measurement data, significantly enhancing the speed of attack detection. Finally, take a smart grid with three generators and six buses as an example. Its feasibility and effectiveness of the Euclidean distance ratio detection algorithm are verified by simulations. The simulations are carried out through the real‐time hardware‐in‐the‐loop simulation platform, which is mainly composed of StarSim and multi‐tasking devices.
This paper mainly studies a detection method for dynamic load altering attacks in smart grids. A smart grid discrete system model under dynamic load altering attack is established, and an adaptive fading Kalman filter is designed to estimate the states of smart grids with Gaussian noise in real time.
This study presents stability charts for estimating the stability of rock mass slopes that are suitable for the generalized Hoek-Brown (GHB) failure criterion based on the strength reduction ...technique. First, in order for implementing the GHB strength reduction, the estimation for the local Mohr-Coulomb (MC) friction angle and cohesive strength from the GHB criterion was incorporated into the strength reduction process in ABAQUS 6.10. Second, stability charts for calculating the FOS of rock slopes with a specific slope angle of β=45° and D=0 are proposed based on this method. Third, the disturbance weighting factors fD and slope angle weighting factor fβ are used to quantify the effect of the rock mass disturbance factor and slope angle on the rock slope stability evaluations. Combined with the stability charts based on β=45° and D=0, the weighting factor fD and fβ can be used to calculate the FOS of rock slopes with various slope angles under different blast damage and stress relief conditions. Finally, the stability charts were applied to two real case studies to illustrate the applicability and validity. The results for the two cases demonstrated good agreement with those from the other charts and the FEM software ABAQUS 6.10. The proposed charts provide a simple and straightforward way to estimate the FOS of the rock mass slopes directly from the GHB parameters.
•Stability charts for calculating the FOS of rock mass slopes are provided.•A simple nonlinear strength reduction for GHB criterion is implemented in ABAQUS 6.10.•The proposed charts are applied to real field cases and the reliability is validated.
As a kind of novel porous ceramics, wood ceramics can be used for filtration, friction, energy storage and electrode materials, etc. In current work, the carbon based wood ceramics (C WCMs) was ...prepared using pine wood powder and phenolic resin as starting materials. The effects of filling rate of wood powder and resin concentration on pore characteristics and properties of C WCMs were characterized and analyzed with different techniques. Furthermore, the association among porosity of C WCMs, filling rate of wood powder and resin concentration was explored with multiple regression model. The results showed that: increasing the resin concentration and the filling rate of wood powder can improve the mechanical properties of C WCMs, but reduce the porosity and air permeability; when resin concentration is more than 50%, a large amount of caking will appear in the C WCMs, causing internal defects; changing the filling rate under a certain resin concentration can obtain the C WCMs with better pore structure; the porosity of C WCMs has a good linear relationship with resin concentration and filling rate, under the condition that sintering process and the size of wood powder are determined.
The reuse of rubber in concrete results in two major opposing effects: an enhancement in durability and a reduction in mechanical strength. In order to strengthen the mechanical properties of rubber ...concrete, steel fibers were added in this research. The compressive strength, the four-point bending strength, the mass loss rate, and the relative dynamic elastic modulus of steel fiber reinforced rubber concrete, subjected to cyclic freezing and thawing, were tested. The effects of the content of steel fibers on the freeze-thaw resistance are discussed. The microstructure damage was captured and analyzed by Industrial Computed Tomography (ICT) scanning. Results show that the addition of 2.0% steel fibers can increase the compressive strength of rubber concrete by 26.6% if there is no freeze-thaw effect, but the strengthening effect disappears when subjected to cyclic freeze-thaw. The enhancement of steel fibers on the four-point bending strength is effective under cyclic freeze-thaw. The effect of steel fibers is positive on the mass loss rate but negative on the relative dynamic elastic modulus.
In this paper, LaCoO
3
porous perovskite was synthesized using wood powder template combined with sol–gel process, while LaCoO
3
prepared by traditional sol–gel method was used as a comparison. The ...catalysts prepared by different methods were characterized by X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), N
2
adsorption–desorption, and the particulate matter (PM) trapping and catalytic oxidation tests were carried out by engine bench test and thermogravimetric analyzer (TGA). The results showed that the porous LaCoO
3
successfully replicated the structural features of wood powder from macroscopic to tracheid, forming a porous structure. Porous LaCoO
3
exhibits better catalytic activity than powdered LaCoO
3
with similar specific surface area, this can be attributed to the porous structure of LaCoO
3
, which increases the contact area and the number of contact points between PM and catalyst.
This study considers the performance impacts of false data injection attacks on the cascading failures of a power cyber-physical system, and identifies vulnerable nodes. First, considering the ...monitoring and control functions of a cyber network and power flow characteristics of a power network, a power cyber-physical system model is established. Then, the influences of a false data attack on the decision-making and control processes of the cyber network communication processes are studied, and a cascading failure analysis process is proposed for the cyber-attack environment. In addition, a vulnerability evaluation index is defined from two perspectives, i.e., the topology integrity and power network operation characteristics. Moreover, the effectiveness of a power flow betweenness assessment for vulnerable nodes in the cyber- physical environment is verified based on comparing the node power flow betweenness and vulnerability assessment index. Finally, an IEEE14-bus power network is selected for constructing a power cyber-physical system. Simulations show that both the uplink communication channel and downlink communication channel suffer from false data attacks, which affect the ability of the cyber network to suppress the propagation of cascading failures, and expand the scale of the cascading failures. The vulnerability evaluation index is calculated for each node, so as to verify the effectiveness of identifying vulnerable nodes based on the power flow betweenness.
Frost damage of concrete has significant effects on the safety and durability of concrete structures in cold regions, and the concrete structures after repair and reinforcement are still threatened ...by cyclic freezing and thawing. In this study, the new-to-old concrete interface was reinforced by steel bar. The shear strength of the new-to-old concrete interface was tested after the new-to-old combination was subjected to cyclic freeze-thaw. The effects of the diameter of the steel bar, the compressive strength of new concrete, the number of freeze-thaw cycles and the freezing temperatures on the shear properties of new-to-old concrete interface were studied. The results showed that, in a certain range, the shear strength of the interface was proportional to the diameter of the steel bar and the strength of the new concrete. Meanwhile, the shear strength of the reinforced interface decreased with the decreasing of the freezing temperature and the increasing of the number of freeze-thaw cycles.
There are detrimental effects of vehicle exhaust pollutants such as particulate matter (PM) and nitrogen oxides (NO
x
) on the environment and human health. In order to enhance the performance of ...woody LaCo
0.7
Fe
0.3
O
3
perovskite-type catalysts for purifying PM and NO
x
, non-thermal plasma (NTP) generated by dielectric barrier discharge (DBD) was used as an assisted preparation method in this paper. The physicochemical properties of LaCo
0.7
Fe
0.3
O
3
perovskite-type catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM), and N
2
adsorption–desorption. The LaCo
0.7
Fe
0.3
O
3
perovskite-type catalysts prepared with and without NTP assisted method were tested and compared by a simulated test bench. The experimental results indicate that the purification efficiency of LaCo
0.7
Fe
0.3
O
3
perovskite-type catalysts for PM and NO
x
with NTP assisted method is significantly higher than LaCo
0.7
Fe
0.3
O
3
perovskite-type catalysts without NTP assisted method. When the input voltage and frequency are 15 kV and 10 kHz, the precursor of the catalyst sample is pretreated for 90 min, and the woody LaCo
0.7
Fe
0.3
O
3
perovskite-type catalyst obtained shows the highest PM and NO
x
purification efficiency, within the range of approximately 96% and 50%, respectively. The PM and NO
x
purification mechanisms were deduced based on the experimental findings.
Vacuolar invertase is involved in sugar metabolism and plays a crucial role in plant growth and development, thus regulating seed size. However, information linking vacuolar invertase and seed size ...in rice is limited. Here we characterized a small grain mutant
(grain size on chromosome 2) that showed a reduced in grain size and 1000-grain weight compared to the wild type. Map-based cloning and genetic complementation showed that
is responsible for the observed phenotype. Loss-of-function of
resulted in grains of smaller size when compared to the wild type, while overexpression showed increased grain size. We also obtained a T-DNA insertion mutant of
, which is a homolog of
and generated double knockout (
) mutants of
and
using CRISPR/Cas9. Genetic data showed that
, that has no effect on grain size by itself, reduces grain length and width in the absence of
. Altered sugar content with increased sucrose and decreased hexose levels, as well as changes vacuolar invertase activities and starch constitution in
,
,
mutants indicate that
and
affect sucrose metabolism in sink organs. In summary, we identified
as a positive regulator of grain size in rice, and while
has no function on grain size by itself. In the absence of
, it is possible to detect a role of
in the regulation of grain size. Both
and
are involved in sucrose metabolism, and thus regulate grain size. Our findings increase our understanding of the role of
and its homolog,
, in grain size development and also suggest a potential strategy to improve grain yield in rice.
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