Methanol steam reforming microreactors can be used for hydrogen production in industry applications. This paper presents a novel thermally autonomous methanol steam reforming microreactor that uses ...porous copper foam as catalyst support to enhance the performance of hydrogen production. The proposed microreactor mainly consists of a vaporizer, a catalytic combustor, and a methanol steam reformer. It uses a Pt/Al2O3 catalyst with 0.15% Pt for methanol combustion and a CuO/ZnO/Al2O3 catalyst-coated copper foam for methanol steam reforming. A numerical model was developed to study the fluid flow and heat transfer characteristics in the porous copper foam and a thin-layer of coated catalyst. Simulation results revealed that the pressure drop and velocity gradient of the microreactor increased when the weight of the catalyst increased. Experimental tests were conducted to study the effects of catalyst loading on the methanol conversion, hydrogen production, and overall efficiency of the microreactor. The results indicate that the developed microreactor can be successfully startup within 13 min and its overall efficiency is approximately 35–45%. The results obtained in this research can be used to develop a highly efficient methanol steam reforming microreactor for hydrogen production.
•A thermally autonomous reactor with copper foam as catalyst support was proposed.•Numerical modeling of copper foam with coated catalyst layer was developed.•Microreactor has better methanol conversion and efficiency for hydrogen production.
The groundwater environment in low-lying coastal regions is significantly impacted by global sea-level fluctuation. In Laizhou Bay, three large-scale transgressions have occurred since the late ...Pleistocene, resulting in the transformation of ancient seawater into brine. This brine has become a major contributor to groundwater salinity in the area. This study establishes a correlation between groundwater occurrence and paleoclimate changes in Laizhou Bay using borehole sediment data. The source and mechanism of groundwater salinity are analyzed based on sediment pore water characteristics and hydrogen and oxygen isotopes. The study reveals that the stratigraphic structures in the area consist of four layers: a Holocene transgressive layer, a continental confining bed from the late Pleistocene, a Cangzhou transgressive layer from the late Pleistocene, and a fluvial aquifer from the middle Pleistocene. All aquifers in the study area have been infiltrated by modern seawater, with the uppermost Holocene aquifer influenced by evaporation and leaching processes, the central late Pleistocene aquifer remaining relatively stable, and the lower middle Pleistocene aquifer affected by subsurface low salinity runoff and exhibiting an increasing trend with depth. Given the presence of numerous hydrogeological environments globally that are similar to the study area, the obtained mechanisms of groundwater salinization in this study will provide theoretical support for groundwater management in similar regions worldwide.
The organ-specific critical nitrogen (N
) dilution curves are widely thought to represent a new approach for crop nitrogen (N) nutrition diagnosis, N management, and crop modeling. The N
dilution ...curve can be described by a power function (N
= A
·W
), while parameters A
and A
control the starting point and slope. This study aimed to investigate the uncertainty and drivers of organ-specific curves under different conditions. By using hierarchical Bayesian theory, parameters A
and A
of the organ-specific N
dilution curves for wheat were derived and evaluated under 14 different genotype × environment × management (G × E × M) N fertilizer experiments. Our results show that parameters A
and A
are highly correlated. Although the variation of parameter A
was less than that of A
, the values of both parameters can change significantly in response to G × E × M. Nitrogen nutrition index (NNI) calculated using organ-specific N
is in general consistent with NNI estimated with overall shoot N
, indicating that a simple organ-specific N
dilution curve may be used for wheat N diagnosis to assist N management. However, the significant differences in organ-specific N
dilution curves across G × E × M conditions imply potential errors in N
and crop N demand estimated using a general N
dilution curve in crop models, highlighting a clear need for improvement in N
calculations in such models. Our results provide new insights into how to improve modeling of crop nitrogen-biomass relations and N management practices under G × E × M.
abstFig src='/00280003/14.jpg' width=""300"" text='A wearable tactile sensor array for three-axis contact force measurement and slip detection in prosthetic hand grasping' Using INASTAMOR ...pressure-conductive rubber as the sensing material, we developed a flexible tactile sensor array to measure three-axis contact force and slip. The sensor array has 9 (3 × 3) sensing units, each consisting of three layers, i.e., a bottom electrode, conductive rubber chips, a top polydimethylsiloxane (PDMS) bump. We detailed the array’s structural design, working principle, and fabrication process. We also characterize the array’s three-axis force measurement performance. The full-scale force measurement ranges and sensitivities in x-, y-, and z-axes are characterized as 5, 5, 20 N and 0.675, 0.677, 0.251 V/N, respectively. The array is mounted on a prosthetic hand for detecting contact force and slip occurrence in grasping. Results showed that the array measures three-axis contact force and detects slippage by using discrete wavelet transformation. The tactile sensor array has potential applications in robot-hand grasping that require simultaneous slip detection and three-axis contact force measurement.
Drug-induced liver injury (DILI) occurs frequently and can be life-threatening. Increasing researches suggest that acetaminophen (APAP) overdose is a leading cause of drug-induced liver injury. ...Indole-3-carboxaldehyde (I3A) alleviates hepatic inflammation, fibrosis and atherosclerosis, suggesting a potential role in different disease development. However, the question of whether and how I3A protects against acetaminophen-induced liver injury remains unanswered. In this study, we demonstrated that I3A treatment effectively mitigates acetaminophen-induced liver injury. Serum alanine/aspartate aminotransferases (ALT/AST), liver malondialdehyde (MDA) activity, liver glutathione (GSH), and superoxide dismutase (SOD) levels confirmed the protective effect of I3A against APAP-induced liver injury. Liver histological examination provided further evidence of I3A-induced protection. Mechanistically, I3A reduced the expression of apoptosis-related factors and oxidative stress, alleviating disease symptoms. Finally, I3A treatment improved survival in mice receiving a lethal dose of APAP. In conclusion, our study demonstrates that I3A modulates hepatotoxicity and can be used as a potential therapeutic agent for DILI.
•I3A alleviated APAP-induced acute liver injury.•I3A attenuated APAP-provoked liver oxidative stress.•I3A attenuated hepatic necrosis in APAP-induced acute liver injury mice.•I3A can improve the survival of lethal doses of APAP-induced mice.
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•A novel wearable tactile sensor array with spatial resolution of 3.5 mm for three-axis distributed contact force sensing is developed.•The tactile sensor array features high ...flexibility and can be easily worn on robotic hand for grasping applications.•Both robotic grasping contact force sensing and slip detection can be achieved by the developed tactile sensor array.•A methodology to determine the threshold values for slip detection is developed.
Distributed tactile information sensing is crucial for the stable grasping and manipulation of intelligent robotics. This paper presents a flexible tactile sensor array with spatial resolution of 3.5 mm that can be easily worn on the robotic hand for distributed three-axis contact force sensing in grasping applications. The proposed tactile sensor array has 3 × 3 sensing units, each unit has a five-electrode pattern’s design and using conductive rubber as the sensing material. The fabricated prototype of the tactile sensor array has good flexibility, and its performance is characterized with high sensitivities: 0.471 V/N in x-axis and 0.466 V/N in y-axis. As for z-axis, the sensitivities are 0.201 V/N at 0˜6 N and 0.067 V/N at 6˜15 N measurement ranges. Then the tactile sensor array and its scanning circuit are integrated into the robotic hand for distributed three-axis contact force perception when grasping different objects. By using discrete wavelet transform analysis, the threshold values of wavelet coefficients for slip detection can be determined, and the slippage during robotic grasping of objects can be successfully detected. Therefore, the developed flexible tactile sensor array has the ability of detecting distributed contact forces and slippage simultaneously, and could be used for robotic dexterous grasping and manipulations.
The rapid development of 3D printing has led to considerable progress in the field of biomedical engineering. Notably, 4D printing provides a potential strategy to achieve a time‐dependent physical ...change within tissue scaffolds or replicate the dynamic biological behaviors of native tissues for smart tissue regeneration and the fabrication of medical devices. The fabricated stimulus‐responsive structures can offer dynamic, reprogrammable deformation or actuation to mimic complex physical, biochemical, and mechanical processes of native tissues. Although there is notable progress made in the development of the 4D printing approach for various biomedical applications, its more broad‐scale adoption for clinical use and tissue engineering purposes is complicated by a notable limitation of printable smart materials and the simplistic nature of achievable responses possible with current sources of stimulation. In this review, the recent progress made in the field of 4D printing by discussing the various printing mechanisms that are achieved with great emphasis on smart ink mechanisms of 4D actuation, construct structural design, and printing technologies, is highlighted. Recent 4D printing studies which focus on the applications of tissue/organ regeneration and medical devices are then summarized. Finally, the current challenges and future perspectives of 4D printing are also discussed.
4D printing is becoming a state‐of‐the‐art research field that holds considerable promise for diverse applications. This article introduces fabrication technologies and transforming strategies in terms of structural design and material composition design. The various 4D inks, actuation mechanisms, and recent advances in tissue regeneration and medical devices are summarized. Finally, the main challenges and future perspectives are presented.
Methanol steam reforming (MSR) has been regarded as a promising hydrogen supply method for proton exchange membrane fuel cell (PEMFC), while the efficiency for hydrogen production and integration ...method of MSR with PEMFC are two major challenges for commercial applications. Here, we present a highly efficient MSR system for hydrogen production and supply for low temperature PEMFC (LT-PEMFC). The MSR system has a highly compact microreactor, wherein MSR, methanol combustion, and CO selective methanation reactions occur. The CO selective methanation is used to reduce the content of CO concentration to remit the CO poison, then the reformate of MSR system is mixed with air and supply for the LT-PEMFC. Then, experimental tests are conducted to investigate the effects of operating parameters on hydrogen production. A staged supply strategy is proposed, it enables to startup the system within 11.2 min and with methanol consumption of 34.72 g. Results show that the methanol conversion can reach up to 93.0% and system's energy efficiency of 76.2%. After integration with a LT-PEMFC, a maximum 160 W electricity can be generated. The results obtained in this study demonstrated that the developed MSR system can be used to supply hydrogen for LT-PEMFC and able to power mobile device requiring hundreds of watts power consumption.
•A novel methanol steam reforming system with CO purification unit is proposed.•The MSR system is integrated with LT-PEMFC and using airbleed to remit CO poison.•The MSR system with integrated LT-PEMFC can generate 160 W of electricity.
Discrimination of surface textures and their surface roughness using tactile sensors have attracted increasing attention. Highly sensitive tactile sensors with the ability to recognize and ...discriminate the surface textures and roughness of grasped objects are crucial for intelligent robotics. We present a methodology by using the developed WMB model and an BP-ANN algorithm to study the performance of a flexible tactile sensor array for surface texture classification. Both numerical modeling and experimental tests demonstrated that the object surface recognition accuracy can reached up to 82 %.
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• Developed a WMB model and BP-ANN algorithm to study the flexible tactile sensor array for surface texture recognition.• The quasi-3D surfaces of objects are reconstructed based on the W-M function.• Surface texture classification accuracy of the tactile sensor array can reach up to 82 %.
Discrimination of surface textures and their surface roughness using tactile sensors have attracted increasing attention. Highly sensitive tactile sensors with the ability to recognize and discriminate the surface textures and roughness of grasped objects are crucial for intelligent robotics. This paper presents a methodology by using the developed WMB model (W-M function and Beam-Bundle Theory) and an algorithm based on artificial neural network to study the performance of a flexible tactile sensor for surface texture classification. For the WMB model, the quasi-3D surfaces of specific objects are reconstructed based on W-M function and basic statistical theory. A simplified Beam-Bundle Model is utilized to represent the cover layer of the sensor and simulates the normal force fluctuations during sliding movements. According to the simulation results, surface textures can be classified by the characteristic frequency cluster (CFC) existing in the fluctuation of curve’s spectrum. As an experiment, an artificial neural network is established to classify surface textures based on voltage signals from the tactile sensor. An MAF array represents the CFC information and improves the classification accuracy from 78 % to 82 %. The results demonstrate the effectiveness of the proposed WMB model and that it provides a new method of analysis involving robotic tactile interactions.
Network security assessment is one of fundamental methods in improving network security. Current assessment methods usually involve manual operations, and require heavy processing overhead. As a ...result, they are not applicable to large complicated networks and cannot provide fast responses needed. This paper proposes an automated assessment approach to address these issues. Firstly, to automate the evaluation process, it analyzes vulnerability information obtained from multiple vulnerability sources (NVD and Bugtraq, etc.), and then correlates them and builds a large integrated vulnerability database consisting of over 40,000 currently-known vulnerabilities. Secondly, to improve the evaluation efficiency, it proposes a new attack graph generation method by exploring the concept of "atomic domain", which significantly reduces generation overhead, compared with traditional methods. Furthermore, the paper constructs a Bayesian evaluation model, and proposes a variable elimination based method which exploits to s
