Study of the anti-penetration performance of concrete with different coarse aggregate content

Abstract Deep penetration experiments were performed on five types of concrete with different coarse aggregate content. The projectile diameter was 29.9 mm, the initial velocity was 647 m/s, and the volume fraction of the coarse aggregate was between 0% and 59.0%. The damage laws and damage mechanism of the target were analyzed. The pure mortar target had the smallest radial crack origin diameter and crater depth. Too high of the coarse aggregate content led to the formation of many voids, which led to the disappearance of radial cracks, crater surface bypassing the coarse aggregate and a large reduction of crater diameter. The influence laws and mechanism of the coarse aggregate on the penetration depth were also analyzed. The increase of volume fraction of coarse aggregate was beneficial to reducing penetration depth and the increase of voids volume fraction was opposite. The penetration depth was the lowest when the volume fraction of the coarse aggregate reached the maximum and no voids formed. By modifying the static resistance stress in the Forrestal penetration formula, a penetration depth model considering the volume fractions of the coarse aggregate and voids was established. The predicted results were in good agreement with the experimental results.</div

Supplementary document for Sim-radon-based shape descriptor for deformable pattern recognition - 6017876.pdf

Supplemental Documen

Study of cracks in concrete target under deep penetration by a projectile

Abstract A large number of cracks occur in concrete structure after projectile penetration. The study of crack distribution and propagation process is the basis of damage assessment, structural repair and high dynamic fracture mechanism. In this paper, wire saw cutting, X-ray computed tomography (X-CT) and mechanical property testing of damaged concrete were carried out on deep penetration targets. According to X-CT images of radial core samples in target and the mechanical properties of damaged concrete, the crack distribution in the target was divided into a plastic damage zone and a brittle damage zone, and the microcracks only existed in the plastic damage zone. The initial growth process of three-dimensional cracks was obtained by X-CT images of axial core samples in target, that is, the cracks in the pure mortar target gradually developed from the radial direction to the tangential direction, and the target containing coarse aggregate directly formed tangential cracks. The propagation progress of cracks was obtained through the target section, that is, the tangential cracks bent in the pure mortar target, and were relatively straight in the target containing coarse aggregate. A crack propagation model was established, and the tangential crack formula and the crack propagation velocity were obtained.</div

π‑Conjugated Lewis Base for Efficient Tin Halide Perovskite Solar Cells with Retarded Sn²⁺ Oxidation

Lead-free tin halide perovskite solar cells (TPSCs) have driven much research attention for their environmental friendliness. However, the low efficiency and large open-circuit voltage (Voc) deficit limit their further development. Here, we introduced a π-conjugated Lewis base, 1H-pyrrolo[2,3-b]pyridin-6-ylaamine (1H6An), a N donor for the unique electron-donating role of pyridine and pyrrole N with unpaired lone pair electrons to interact with the tin halide perovskites and thus retard the oxidation of Sn2+ during the aging process of precursors. Meanwhile, the interaction stabilized the perovskite lattice and decreased the microstrain of deposited films. The carrier kinetics further revealed a notably enhanced carrier extraction and transport as well as decreased nonradiative recombination with 1H6An. Consequently, this approach delivered an efficiency of 13.28% with a remarkable Voc enhancement from 853 to 907 mV. Meanwhile, the 1H6An device exhibited an extended lifespan of over 2500 h with around 90% retention of its initial value in a N2 atmosphere

Large-Scale Syntheses of Multicolor Stimulus Responsive Room-Temperature Phosphorescent Polymer-Carbonyl-Modified Carbon Nitrogen Quantum Dots

Carbonyl-modified solid-state carbon nitrogen quantum dots (m-OCNQDs) have emerged as promising room-temperature phosphorescent (RTP) materials close to commercialization. However, high-crystallinity m-OCNQDs are insensitive to external stimuli such as water and heat due to strong stacking interactions between layers, restricting their applications in stimulus responsive fields. Here, a polymer template space-confined growth strategy is established for the large-scale synthesis of water stimulus responsive polyvinylpyrrolidone-functionalized m-OCNQDs with ultralong room-temperature phosphorescence (181 ms) using urea and PVP as precursors. Theoretical and experimental results indicate that the PVP template linked at the rim of m-OCNQDs formed by in situ self-polymerization of urea inhibits interactions between layers and increases their affinity for water, which is the key to increasing their sensitivity with water. This strategy offers a new path for developing commercial stimulus responsive RTP materials

Large-Scale Syntheses of Multicolor Stimulus Responsive Room-Temperature Phosphorescent Polymer-Carbonyl-Modified Carbon Nitrogen Quantum Dots

Carbonyl-modified solid-state carbon nitrogen quantum dots (m-OCNQDs) have emerged as promising room-temperature phosphorescent (RTP) materials close to commercialization. However, high-crystallinity m-OCNQDs are insensitive to external stimuli such as water and heat due to strong stacking interactions between layers, restricting their applications in stimulus responsive fields. Here, a polymer template space-confined growth strategy is established for the large-scale synthesis of water stimulus responsive polyvinylpyrrolidone-functionalized m-OCNQDs with ultralong room-temperature phosphorescence (181 ms) using urea and PVP as precursors. Theoretical and experimental results indicate that the PVP template linked at the rim of m-OCNQDs formed by in situ self-polymerization of urea inhibits interactions between layers and increases their affinity for water, which is the key to increasing their sensitivity with water. This strategy offers a new path for developing commercial stimulus responsive RTP materials

Pseudohalide-Modulated Crystallization for Efficient Quasi-2D Tin Perovskite Solar Cells with Minimized Voltage Deficit

Regulating the crystallization dynamics and suppressing the oxidation of Sn2+ is imperative for the emerging lead-free tin perovskite solar cells (TPSCs). In this respect, quasi-2D tin perovskites exhibit relatively slow crystallization and crystal growth rate compared to the three-dimensional analogues. However, these dimensional-mixed tin perovskites suffer from random orientation, which limits the charge carrier transport for photovoltaic applications. Herein, we report a facile and feasible strategy to modulate the dimensionality and crystallization of tin perovskites with the incorporation of phenethylammonium thiocyanate (PEASCN), which is exploited to deliver a high-quality crystal growth and preferred alignment. The pseudohalide SCN– can effectively hinder Sn2+ oxidation by synergistically modulating the coordination and crystal growth of Sn perovskite films. Meanwhile, these interactions significantly suppressed the nonradiative charge recombination. Finally, a high efficiency approaching 12.88% with an open-circuit voltage (Voc) of 863 mV is achieved for the inverted TPSCs. The obtained Voc is among the highest reported values for indene-C60 (ICBA)-free TPSC devices. The PEASCN devices also exhibited high stability for over 2000 h under a N2 atmosphere

Large-Scale Syntheses of Multicolor Stimulus Responsive Room-Temperature Phosphorescent Polymer-Carbonyl-Modified Carbon Nitrogen Quantum Dots

Carbonyl-modified solid-state carbon nitrogen quantum dots (m-OCNQDs) have emerged as promising room-temperature phosphorescent (RTP) materials close to commercialization. However, high-crystallinity m-OCNQDs are insensitive to external stimuli such as water and heat due to strong stacking interactions between layers, restricting their applications in stimulus responsive fields. Here, a polymer template space-confined growth strategy is established for the large-scale synthesis of water stimulus responsive polyvinylpyrrolidone-functionalized m-OCNQDs with ultralong room-temperature phosphorescence (181 ms) using urea and PVP as precursors. Theoretical and experimental results indicate that the PVP template linked at the rim of m-OCNQDs formed by in situ self-polymerization of urea inhibits interactions between layers and increases their affinity for water, which is the key to increasing their sensitivity with water. This strategy offers a new path for developing commercial stimulus responsive RTP materials

Does dexmedetomidine have an antiarrhythmic effect on cardiac patients? A meta-analysis of randomized controlled trials

<div><p>Background</p><p>Cardiac surgery patients often experience several types of tachyarrhythmias after admission to the intensive care unit (ICU), which increases mortality and morbidity. Dexmedetomidine (DEX) is a popular medicine used for sedation in the ICU, and its other pharmacological characteristics are gradually being uncovered.</p><p>Purpose</p><p>To determine whether DEX has an antiarrhythmic effect after cardiac surgery.</p><p>Methods</p><p>The three primary databases MEDLINE, Embase (OVID SP) and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched, and all English-language and randomized control-designed clinical publications comparing DEX to control medicines for sedation after elective cardiac surgery were included. Two colleagues independently extracted the data and performed other quality assessments. A subgroup analysis was performed according to the different medicines used and whether cardiopulmonary bypass (CPB) was applied. All tachyarrhythmias that occurred in the atria and ventricles were analyzed.</p><p>Results</p><p>A total of 1295 patients in 9 studies met the selection criteria among 2587 studies that were screened. After quantitative synthesis, our results revealed that the DEX group was associated with a lower incidence of ventricular arrhythmia (VA, OR 0.24, 95% CI 0.09–0.64, I² = 0%, P = 0.005) than the control group. Subgroup analysis did not reveal a significant difference between the DEX and propofol subgroups (OR 0.13, 95% CI 0.03–0.56, I² = 0%, P = 0.007). Additionally, no difference in the incidence of atrial fibrillation (AF) was observed regardless of the different control medicines (OR 0.82, 95% CI 0.60–1.10, I² = 25%, P = 0.19) or whether CPB was applied.</p><p>Conclusions</p><p>This meta-analysis revealed that DEX has an antiarrhythmic effect that decreases the incidence of VA compared to other drugs used for sedation following cardiac surgery. DEX may not have an effect on AF, but cautious interpretation should be exercised due to high heterogeneity.</p></div

Constructing Efficient Hole Transport Material through π‑Conjunction Extension for Perovskite Solar Cell

Efficient hole transport and excellent film formation properties are essential for efficient hole transport materials (HTMs) in perovskite solar cells (PCSs). And, the π-conjugated system and the steric configuration of HTMs can affect charge-carrier mobility and film formation. So, it is feasible to develop efficient HTMs via optimizing the molecular configuration and enlarging the π-conjugation system. Herein, a low-cost spiro[fluorene-9,9′-xanthene] (SFX) core-based HTM, named SFX-DM-DPA, is designed and synthesized through molecular engineering of the efficient HTM SFX-DM by introducing extra 4,4′-dimethoxydiphenylamine units to enlarge the π-conjugation range and to further modulate the charge transport property. The resulting HTM demonstrates enhanced hole extraction/transport efficiency and desired film formation ability. PSCs based on SFX-DM-DPA yielded an impressive efficiency of 22.7%. These results confirmed the importance of precise structural adjustment of the π-conjugated range for developing low-cost and highly efficient HTMs