•A 3D multiple-reflection model was developed to simulate full penetration laser welding.•Extreme spreading of bottom molten pool and followed hump formation were analyzed.•Periodic behavior of ...keyhole in quasi-steady stage was identified.•Keyhole-induced porosity formation mechanism in full penetration was proposed.
To study molten pool dynamics, root hump formation, periodic keyhole behavior in full penetration laser welding (FPLW) of aluminum alloy, a numerical simulation was carried out, in which volume of fluid (VOF) method and ray-tracing algorithm were adopted. A varied metallic vapor shear stress model was considered. Meanwhile a series of welding experiments on specimens being composed of aluminum alloy and quartz glass were conducted to analyze the porosity formation process. It was found that the over-heated sagging with low surface tension stagnated at the bottom side and solidified to form root hump. The dominant backward heat convection at the lower part can well explain the extreme spreading of molten pool at bottom surface. Periodic behavior of the keyhole was identified during quasi-steady stage. The porosity can be effectively suppressed in FPLW. Both the porosity ratio and average porosity number were reduced obviously. The main mechanism of porosity formation in FPLW is the collapse of the rear keyhole wall, mainly caused by bulges on the front keyhole wall. Bubble coalescence is responsible for large porosity size and coalescence efficiency depends on bubble size difference.
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To achieve the optimal alginate-based oral formulation for delivery of hydrophobic drugs, on the basis of previous research, we further optimized the synthesis process parameters of ...alginate-g-oleylamine derivatives (Ugi-FOlT) and explored the effects of different degrees of substitution (DSs) on the molecular self-assembly properties of Ugi-FOlT, as well as the in vitro cytotoxicity and drug release behavior of Ugi-FOlT. The resultant Ugi-FOlT exhibited good amphiphilic properties with the critical micelle concentration (CMC) ranging from 0.043 mg/mL to 0.091 mg/mL, which decreased with the increase in the DS of Ugi-FOlT. Furthermore, Ugi-FOlT was able to self-assemble into spherical micellar aggregates in aqueous solution, whose sizes and zeta potentials with various DSs measured by dynamic light scattering (DLS) were in the range of 653 ± 25~710 ± 40 nm and −58.2 ± 1.92~−48.9 ± 2.86 mV, respectively. In addition, RAW 264.7 macrophages were used for MTT assay to evaluate the in vitro cytotoxicity of Ugi-FOlT in the range of 100~500 μg/mL, and the results indicated good cytocompatibility for Ugi-FOlT. Ugi-FOlT micellar aggregates with favorable stability also showed a certain sustained and pH-responsive release behavior for the hydrophobic drug ibuprofen (IBU). Meanwhile, it is feasible to control the drug release rate by regulating the DS of Ugi-FOlT. The influence of different DSs on the properties of Ugi-FOlT is helpful to fully understand the relationship between the micromolecular structure of Ugi-FOlT and its macroscopic properties.
Thermal barrier coatings are applied to the protection of metal components in aircraft thrusters, power generation and ship gas turbine engines, which can make the gas turbine run for a long time in ...a high-temperature environment. The fracture toughness of the coating characterizes the ability of the material to prevent crack propagation and is one of the most important factors to be taken into consideration to prolong the life of the thermal barrier coating. The current research is mainly through dispersion toughening, the phase transformation toughening, whisker toughening, ferroelastic toughening, and other methods to improve the fracture toughness of ceramic coatings. In this paper, the use of different toughening mechanisms and the addition of unique materials to improve the fracture toughness of thermal barrier coatings are introduced, and the future research direction is put forward.
The SM4 block cipher is standardized in ISO/IEC, and it is also the national standard of commercial cryptography in China. In this paper, we propose two new techniques called “split‐and‐join” and ...“off‐peak and stagger” to make SM4 more applicable to resource‐constrained environments. The area optimization method uses a 1‐bit data path while reducing the number of registers from 64 to 8 and the number of XOR gates from 194 to 8. As a result, we report a 1‐bit‐serial SM4 encryption circuit that occupies 1771 GE with a latency of 2,336 cycles. Additionally, the “off‐peak and stagger” technique compresses all the operations within the state update and key schedule into 32 clock cycles to reduce the latency. In other words, it takes 32 clock cycles to complete one round encryption. The new circuit occupies 1861 GE with a latency of 1,344 cycles. Moreover, we also discuss how to further reduce the latency by increasing the data path with a small area overhead to provide wider area‐latency tradeoffs for SM4. Our designs make SM4 competitive with many ciphers specifically designed for lightweight cryptography.
Underwater optical wireless communication (UOWC) has great potential to provide high-speed and intensive communications over short ranges underwater. However, the mobility of the UOWC system is ...limited by the strict alignment requirements between the transceivers. In this paper, a multi-degree-of-freedom (MDOF) UOWC system with high flexibility and improved transmission performance is proposed and experimentally demonstrated based on the off-the-shelf light-emitting diode (LED) source. A hardware pre-equalization circuit is employed at the transmitter to extend the modulation bandwidth from 5.03 MHz to 50 MHz. At the receiving end, a Fresnel lens array is constructed to achieve efficient convergence of multiple incident optical signals from different directions. To improve the underwater signal transmission quality, we designed an additional digital signal recovery module after the trans-impedance amplifier. Finally, an experimental system is established with a 460 nm blue LED. The communication reliability of the system is verified by the measurement of the eye diagram and the bit error rate of the recovered signal at the receiving end. The experimental results show that optical signals from three different incident directions with a maximum data rate of 100 Mbps are reliably transmitted over a 1.2-m-long water tank using the non-return-to-zero on-off-keying modulation format.
Bile acid (BA) receptors (e.g., farnesoid X-activated receptor, muscarinic receptor) are expressed in cardiomyocytes, endothelial cells, and vascular smooth muscle cells, indicating the relevance of ...BAs to cardiovascular disease (CVD). Hydrophobic BAs are cardiotoxic, while hydrophilic BAs are cardioprotective. For example, fetal cardiac insufficiency in maternal intrahepatic cholestasis during pregnancy, and the degree of fetal cardiac abnormality, is closely related to the level of hydrophobic BAs in maternal blood and infant blood. However, ursodeoxycholic acid (the most hydrophilic BA) can reverse/prevent these detrimental effects of increased levels of hydrophobic BAs on the heart. The gut microbiota (GM) and GM metabolites (especially secondary BAs) have crucial roles in hypertension, atherosclerosis, unstable angina, and heart failure. Herein, we describe the relationship between CVD and the GM at the BA level. We combine the concept of the “microbiota–gut–heart axis” (MGHA) and postulate the role and mechanism of BAs in CVD development. In addition, the strategies for treating CVD with BAs under the MGHA are proposed.
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Transplantation of neural stem cells (NSCs) has been proved to promote functional rehabilitation of brain lesions including ischemic stroke. However, the therapeutic effects of NSC transplantation ...are limited by the low survival and differentiation rates of NSCs due to the harsh environment in the brain after ischemic stroke. Here, we employed NSCs derived from human induced pluripotent stem cells together with exosomes extracted from NSCs to treat cerebral ischemia induced by middle cerebral artery occlusion/reperfusion in mice. The results showed that NSC-derived exosomes significantly reduced the inflammatory response, alleviated oxidative stress after NSC transplantation, and facilitated NSCs differentiation in vivo. The combination of NSCs with exosomes ameliorated the injury of brain tissue including cerebral infarction, neuronal death, and glial scarring, and promoted the recovery of motor function. To explore the underlying mechanisms, we analyzed the miRNA profiles of NSC-derived exosomes and the potential downstream genes. Our study provided the rationale for the clinical application of NSC-derived exosomes as a supportive adjuvant for NSC transplantation after stroke.
Problem finding
(PF) is a crucial element of creative thinking. PF facility allows us to manage the rapidly changing world. Tolerance of ambiguity (AT) is a personality variable that plays a vital ...role in creative thinking. However, few studies have explored PF’s brain mechanisms and their relationship with AT. This study aimed to filled this gap using behavioral and voxel-based morphometry (VBM) methods. The behavioral results revealed a significant positive correlation between AT and PF. The VBM analysis found that novel PF positively correlated with the cluster’s regional gray matter density (GMD) involving the left dorsolateral prefrontal cortex (DLPFC) and precentral cortex. Additionally, novel and appropriate PF was positively correlated with the GMD of the right inferior frontal gyrus (IFG) and regional white matter density (WMD) of the bilateral thalamus. Further mediation analysis revealed that the rGMD of the right IFG mediated the relation between AT and PF, which showed that the right IFG is associated with inhibitory control and novelty-seeking. Individuals with high AT and regional GMD in right IFG had a greater novel and appropriate PF ability. These findings shed light on the correlation between AT and PF from the brain’s structural basis perspective.
This study examined whether maternal depression is related to Early Childhood Developmental (ECD) delay among children by quantifying the mediating contribution of responsive caregiving. We used data ...from 1235 children (Children's mean age = 50.4 months; 582 girls, 653 boys, 93.9% were Han), selected through convenience sampling, in 2021. 4.7% of children had ECD delay, 34.3% of mothers had depression. Children with depressed mothers were less likely to receive responsive caregiving (OR 4.35, 95% CI 2.60-7.27), and those who did not receive responsive caregiving were more likely to experience ECD delay (OR 3.89, 95% CI 1.89-8.02). Responsive caregiving partly mediated the relationship between maternal depression and ECD. Early intervention for children with depressed mothers is worthy of further investigation.This study examined whether maternal depression is related to Early Childhood Developmental (ECD) delay among children by quantifying the mediating contribution of responsive caregiving. We used data from 1235 children (Children's mean age = 50.4 months; 582 girls, 653 boys, 93.9% were Han), selected through convenience sampling, in 2021. 4.7% of children had ECD delay, 34.3% of mothers had depression. Children with depressed mothers were less likely to receive responsive caregiving (OR 4.35, 95% CI 2.60-7.27), and those who did not receive responsive caregiving were more likely to experience ECD delay (OR 3.89, 95% CI 1.89-8.02). Responsive caregiving partly mediated the relationship between maternal depression and ECD. Early intervention for children with depressed mothers is worthy of further investigation.
Although electrochemical disinfection has been shown to be an effective approach to inactivate bacteria in saline water, the effects of process parameters and reactor design for its application in ...low-salinity water have not been well understood. In this study, factorial experiments were performed to investigate the direct and confounded effects of applied current (5–20 mA), contact time (2.5–20 min), anode surface area (185–370 cm
2
), and chloride concentration (50–400 mg L
−1
) on the disinfection efficiency in fresh water and the secondary effluent of municipal wastewater. An electrochemical disinfection reactor cell with an internal volume of 75 cm
3
was designed and fabricated. Residence time distribution analysis showed that the internal mixing of the reactor is similar to that of a dispersed plug-flow reactor. All studied process parameters showed significant effect on the kill efficiency, with the applied current and contact time having the most dominant effect. Although the effect of chloride concentration, which is responsible for electrochemical production of free chlorine in water, is statistically significant, it is not as prominent as those reported for high salinity water. A synergistic effect between chloride concentration and anode surface area was identified, leading to high kill efficiency (99.9%, 3 log kill) at low current density (0.0135 mA cm
−2
). Response surface modeling results suggested that a scaled-up disinfection reactor can be designed using large anode surface area with long contact time for high chloride water (400 mg L
−1
) or high current density with short contact time for low chloride water (50 mg L
−1
). The power requirement of a portable system treating 37.85 m
3
day
−1
(10,000 gpd) of municipal wastewater was estimated to be 1.9 to 8.3 kW to achieve a 3 log kill, depending on the reactor design.
