The development and application of wire electrochemical micromachining (WECMM) technology have become a research hotspot of non-traditional machining. However, a series of problems cannot be ...eliminated due to the machining products of micromachining gap, which leads to poor machining performance. This paper proposed a new method named ultrasonic vibration–added wire electrochemical micromachining (UA-WECMM) technology, which can solve the mass transfer problem in WECMM with extremely narrow gap. Firstly, the flow field of machining gap was simulated. The results showed that the pressure range of machining gap was larger and was more conducive to the renewal of electrolyte when ultrasonic vibration was added. Secondly, the effects of ultrasonic amplitude and ultrasonic vibration object on machining accuracy and surface quality were compared by experiments, which illustrated that the machining performance was greatly improved with the increase of ultrasonic amplitude of the workpiece. The slit width can be reduced from 196.2 to 151.2 μm, and the surface roughness can be reduced from
R
a
0.863 to
R
a
0.259 μm. Finally, the micro-gear structure with surface roughness of
R
a
0.263 μm and depth-to-width ratio of 6.7:1 was fabricated, which proved that UA-WECMM technology is an effective technology for fabricating metal microstructures with high aspect ratio and good machining quality.
Flexible perovskite solar cells (FPSCs) have emerged as power sources in versatile applications owing to their high-efficiency characteristics, excellent flexibility, and relatively low cost. ...Nevertheless, undesired strain in perovskite films greatly impacts the power-conversion efficiency (PCE) and stability of PSCs, particularly in FPSCs. Herein, a novel multifunctional organic salt, methylammonium succinate, which can alleviate strain and reinforce grain boundaries, was incorporated into the perovskite film, leading to relaxed microstrain and a lower defect concentration. As a result, a PCE of 25.4% for rigid PSCs and a record PCE of 23.6% (certified 22.5%) for FPSCs have been achieved. In addition, the corresponding FPSCs exhibited excellent bending durability, maintaining ∼85% of their initial efficiency after bending at a 6 mm radius for 10 000 cycles.
Display omitted
•FPSCs hold promise as power sources for flexible electronics and spacecraft•Succinate additives enable high-quality perovskite films with reduced microstrain•An efficiency of 25.4% has been achieved for perovskite solar cells•An efficiency of 23.6% has been achieved for FPSCs with excellent durability
Previous studies on the treatment of hepatic cirrhosis have been focusing on how to inhibit liver fibrosis, while ignoring liver inflammation, a key and underlying factor that promotes cirrhosis. ...High mobility group box-1 (HMGB1) protein, a pro-inflammatory factor and fibroblast chemokine, can promote the proliferation of hepatic stellate cells (HSCs) and the development of hepatic inflammation and fibrosis, playing a key role in cirrhosis formation. In this study, we prepared pPB peptide (C*SRNLIDC*)-modified and HMGB1-siRNA-loaded stable nucleic acid lipid nanoparticles (HMGB1-siRNA@SNALP-pPB) to effectively treat hepatic cirrhosis by their dual antifibrotic and anti-inflammatory activities. The pPB peptide-modified and heat shock protein 47 (HSP47)-siRNA-loaded stable nucleic acid lipid nanoparticles (HSP47-siRNA@SNALP-pPB), which have only an antifibrotic effect without an anti-inflammatory effect, was used as control. The results demonstrated that HMGB1-siRNA@SNALP-pPB were actively targeted to HSCs by the mediation of pPB peptide, effectively silenced the HMGB1 gene, inhibited the activation and proliferation of HSCs, reduced the release of HMGB1 protein, inhibited collagen deposition and fibrosis formation in the liver, and significantly prolonged the survival time of cirrhotic mice models. HMGB1-siRNA@SNALP-pPB showed a stronger therapeutic effect on liver cirrhosis than HSP47-siRNA@SNALP-pPB. This study provides an actively targeted siRNA delivery system for cirrhosis treatment based on the dual antifibrotic and anti-inflammatory effects. In addition, this study clarified the role of inflammatory problems in cirrhosis treatment in addition to liver fibrosis, providing a useful idea and scientific basis for the development of cirrhosis treatment strategies in the future.
Mobile manipulator robots have become important pieces of equipment due to the high mobility of mobile subsystems and the high flexibility of manipulator subsystems. Considering the increasing ...degrees of freedom and the need to avoid singular locations, one of the most challenging problems is solving the inverse kinematics problem of mobile manipulator robots (IKMM). Of all the popular optimization algorithms, the differential evolution (DE) algorithm is the most effective method for quickly solving the IKMM problem with sufficient solutions. Currently, many strategies have been proposed for DE algorithms to improve the performance of solving mathematical problems; some symmetry strategies or symmetry functions have been introduced to DE algorithms. However, the effects of various DE algorithms on solving the actual IKMM lack a comprehensive explanation. Therefore, we divide various DE algorithms into three categories considering the control parameter selection and compare the specific optimization of various DE algorithms. Then, we compare the performance of various DE algorithms when solving the inverse kinematics problems of mobile manipulators with different degrees of freedom. Considering the effectiveness and the speed of the DE algorithm on the IKMM problem, we determine the best DE algorithm by comparing the error and time required to reach 100 random mission points and tracking the typical trajectories. Finally, the best-performing DE method is further improved by studying the selection of fundamental parameters in the best DE algorithm. Valuable conclusions are obtained from these experimental simulations, which can help with choosing an algorithm that is suitable for solving the inverse kinematics problem of mobile manipulator robots in practice.
Abstract
We study experimentally the impact of inertial reference frame changes on overdamped Brownian motion. The reference frame changes are implemented by inducing, with a laser, laminar ...convection flows in a column of fluid where Brownian microspheres are dispersed. The convection flow plays the role of the relative velocity between the laboratory and the fluid comoving frames, and enables us to analyse the consequences of Galilean transformations on Brownian diffusion. We verify in particular how the Brownian dynamics remains ‘weakly’ Galilean invariant, in agreement with recent discussions Cairoli
et
al
(2018
Proc. Natl Acad. Sci. USA
115
5714). We also carefully look at the consequences of Galilean relativity on the Brownian energetics. This leads us to derive a Galilean invariant expression of the stochastic thermodynamic first law, consistent with existing theoretical results Speck
et
al
(2008
Phys. Rev. Lett.
100
178302). We finally discuss a potential ambiguity of the Galilean relativistic features of diffusive systems that has obvious practical implications in the context of force measurements in external flows.
Vacuum evaporation is promising for the scalable fabrication of perovskite solar cells (PSCs). Nevertheless, the poor thermal conductivity of metal halide powder leads to unfavorable temperature ...inhomogeneity, which destabilizes the evaporation rate, posing a major challenge to the reproducible deposition of perovskite films, particularly by coevaporation. Herein, a molten salt strategy is reported for sequentially vacuum evaporation of PSCs. The molten salt increases the thermal conductivity of metal halides and greatly homogenizes the temperature, which stabilizes the evaporation rate and the composition of the resulting perovskite films. The PSCs yield power conversion efficiencies (PCEs) of ≈24% with exceptional reproducibility. The unencapsulated PSCs maintain 85% of the initial PCE after 3600 h of maximum power point tracking and maintain 85% of the initial PCE after being heated at 60 °C for 3000 h. The molten salt strategy opens a new avenue for the application of evaporation in perovskite optoelectronics.
Molten salt strategy enables the fabrication of perovskite solar cells by two‐step sequential vacuum evaporation with exceptional reproducibility. The PSCs yield power conversion efficiencies of ≈24% and have good operational stability and shelf‐life stability. The strategy has good expansibility in fabricating PSCs with tunable bandgaps.
•The recovery performance of the self-centering steel-timber hybrid beam-column connections was investigated through the recovery testing.•A quantitative evaluation on hybrid connections’ competence ...in recovering their stiffness, moment capacity, ability in dissipating energy and re-centering, and the control on the loss of the post-tensioning force, was conducted.•The effects of three variables, including the initial post-tensioning force, energy dissipator types, and key parameters of dampers, on connections’ recovery performance were compared.
A self-centering steel-timber hybrid beam-column connection design was proposed to improve performance of conventional self-centering timber beam-column connections. The proposed connection utilized a steel-timber composite column to prevent the wood material from being compressed perpendicular to the grain. In this paper, the recovery performance of the hybrid connection was experimentally investigated. Six specimens were prepared for the recovery testing. Three experimental variables, including the initial post-tensioning force, energy dissipator types (sliding friction and metallic yielding), and key parameters of dampers, were considered. After the first loading, the specimens reached their ultimate performance with damage. Then specimens were repaired and loaded for the second time. Five recovery indexes were calculated to quantitatively evaluate the recovery performance of hybrid connections. The effects of different variables on the recovery ability of hybrid connections were explored.
Significance
Intestinal barrier plays a key role in maintaining organismal health. Here we find cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS) deficiency compromises ...intestinal epithelial barrier and exacerbates inflammation. cGAS-deficient mice were highly susceptible to colitis-associated colon cancer (CAC) but not sporadic colon cancer. Surprisingly, the role of cGAS in this process appears to be independent of stimulator of interferon genes (STING)-induced type I interferon signaling, because mice lacking STING or type I interferon receptor were less susceptible to CAC than those lacking cGAS. cGAS but not STING is highly expressed in intestinal stem cells. These results suggest that cGAS has a unique role in protecting the intestinal epithelial barrier and preventing colon cancer development.
The DNA-sensing enzyme cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS) regulates inflammation and immune defense against pathogens and malignant cells. Although cGAS has been shown to exert antitumor effects in several mouse models harboring transplanted tumor cell lines, its role in tumors arising from endogenous tissues remains unknown. Here, we show that deletion of cGAS in mice exacerbated chemical-induced colitis and colitis-associated colon cancer (CAC). Interestingly, mice lacking cGAS were more susceptible to CAC than those lacking stimulator of interferon genes (STING) or type I interferon receptor under the same conditions. cGAS but not STING is highly expressed in intestinal stem cells. cGAS deficiency led to intestinal stem cell loss and compromised intestinal barrier integrity upon dextran sodium sulfate-induced acute injury. Loss of cGAS exacerbated inflammation, led to activation of STAT3, and accelerated proliferation of intestinal epithelial cells during CAC development. Mice lacking cGAS also accumulated myeloid-derived suppressive cells within the tumor, displayed enhanced Th17 differentiation, but reduced interleukin (IL)-10 production. These results indicate that cGAS plays an important role in controlling CAC development by defending the integrity of the intestinal mucosa.
Heat is a powerful stressor for fish living in natural and artificial environments. Understanding the effects of heat stress on the physiological processes of fish is essential for better aquaculture ...and fisheries management. In this experiment, a heating rod was used to increase the temperature at 2°C/h to study the changes of energy allocation (CEA) and energy metabolity-related enzyme activities, including pepsin, trypsin, amylase, lipase, acid phosphatase, lactate dehydrogenase, alanine aminotransferase, glutamic oxalic aminotransferase and energy reserve (Ea), energy expenditure (ETS), in juvenile yellowfin tuna cells under acute temperature stress. The results showed that the Ea of juvenile yellowfin tuna muscles in response to high temperature (34°C) was significantly lower than that of the control (28°C), and it also increased ETS. At 6 h, CEA decreased slightly in the high-temperature group, but, the difference in CEA between 24 h and 0 h decreased. After heat stress for 6 h, the activities of acid phosphatase (ACP), lactate dehydrogenase (LDH), alanine aminotransferase (ALT) and glutamic oxalacetic transaminase (AST) increased, indicating that the metabolic rate was accelerated. After heat stress for 24 h, the activity of ALT decreased, indicating that with time elapsed, the activities of some protein metabolizing enzymes increased, and some decreased. In this study, digestive enzymes, trypsin and lipase increased gradually. After heat stress, Ea and Ec change significantly. Yellowfin tuna muscles use lipids in response to sharp temperature increases at high temperatures, red muscles respond to temperature changes by increasing energy in the early stages, but not nearly as much, and white muscles reduce lipids.
Coal seam gas extraction is an important means of exploiting and utilizing gas resources, as well as a means of preventing coal mine disasters. To improve gas extraction efficiency in high gas and ...low permeability coal seams while ensuring blasting security, deep hole cumulative blasting parameters were optimized. ANSYS/LS-DYNA software is used to establish a 3-dimensional cumulative blasting model. By comparing and analyzing the blasting stress nephograms, stress time-history curves, and crack expansion curves, the optimal blasthole diameter, charge position, and charge length are obtained. Based on the numerical simulation results, a field test was carried out in the No. 10 coal seam of the Pingdingshan coal mine. The test results show that after cumulative blasting, the gas concentration was increased by an average of 2.25 times, the gas purity was increased by an average of 3.78 times, the permeability coefficient of the coal seam was increased by 21 times, and the effective radius of blasting was up to 7 m. The positive effects of deep hole cumulative blasting parameter optimization on the pressure relief and permeability enhancement of a high gas and low permeability coal seam were determined, which can provide a reference for other similar working faces to implement this technology.
PDF
