High efficient, cost-effective catalysts for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are the key issue of the rechargeable lithium-air batteries. Herein, we ...report the facile synthesis of hierarchical NiCo2O4 (NCO) hollow nanospheres via a hard template method and following heat treatment. The synthesized hollow NCO consists of ultrathin nanosheets, which could provide larger specific surface area, more active sites and easy access channels for oxygen and electrolyte transport. The electrochemical studies reveal that the NCO hollow owns excellent ORR and OER catalytic activities, characterized with lower onset potential, higher diffusion limiting current density. Moreover, the NCO hollow shows superior stability compared to that of NCO urchin, Pt/C and RuO2 for ORR and OER, respectively. The excellent electrocatalytic activities, long-term stability for both the ORR and OER and the facile synthesis procedure make the NCO hollow a potential promising bi-functional catalyst for the metal-air batteries and fuel cells.
•Hierarchical NiCo2O4 hollow nanospheres have been prepared via a hard template method.•The synthesized NCO hollow consists of ultrathin nanosheets.•The NCO hollow exhibits excellent catalytic activity for both ORR and OER.•The NCO hollow also owns superior long-term stability.
This paper proposes the design and implementation of a model predictive control (MPC) algorithm for a micro-permanent-magnet synchronous motor (micro-PMSM)-based five-finger control system. First, ...the kinematic analysis and inverse kinematics of the micro-finger system are developed. The relationship between the rotor position of micro-PMSM and the position of the micro-fingertip is determined. Then, an MPC algorithm is designed to improve the performance of the micro-PMSM control system. An embedded system, cRIO-9024/9112, is used as a control center to execute the position control algorithm and force control algorithm. Experimental results show that the proposed system provides satisfactory transient responses, load disturbance responses, and tracking responses. In addition, the proposed five-finger system can grasp some objects by using the proposed force feedback control and a trajectory planning algorithm.
The small intestine epithelium renews every 2 to 5 days, making it one of the most regenerative mammalian tissues. Genetic inducible fate mapping studies have identified two principal epithelial stem ...cell pools in this tissue. One pool consists of columnar Lgr5-expressing cells that cycle rapidly and are present predominantly at the crypt base. The other pool consists of Bmi1-expressing cells that largely reside above the crypt base. However, the relative functions of these two pools and their interrelationship are not understood. Here we specifically ablated Lgr5-expressing cells in mice using a human diphtheria toxin receptor (DTR) gene knocked into the Lgr5 locus. We found that complete loss of the Lgr5-expressing cells did not perturb homeostasis of the epithelium, indicating that other cell types can compensate for the elimination of this population. After ablation of Lgr5-expressing cells, progeny production by Bmi1-expressing cells increased, indicating that Bmi1-expressing stem cells compensate for the loss of Lgr5-expressing cells. Indeed, lineage tracing showed that Bmi1-expressing cells gave rise to Lgr5-expressing cells, pointing to a hierarchy of stem cells in the intestinal epithelium. Our results demonstrate that Lgr5-expressing cells are dispensable for normal intestinal homeostasis, and that in the absence of these cells, Bmi1-expressing cells can serve as an alternative stem cell pool. These data provide the first experimental evidence for the interrelationship between these populations. The Bmi1-expressing stem cells may represent both a reserve stem cell pool in case of injury to the small intestine epithelium and a source for replenishment of the Lgr5-expressing cells under non-pathological conditions.
Critical temperature and critical pressure of binary mixture of carbon dioxide (CO
2
) and propylene (R-1270) are measured in this study. Critical point is determined by the observation of ...disappearance and reappearance of the meniscus in a sapphire view cell. The experimental data were correlated by the Redlich–Kister equations, and the correlated results showed a good agreement with experimental data with average absolute deviation of 0.08% for critical temperature and 0.14% for critical pressure, respectively. Also, the experimental data are compared with the prediction results of Peng-Robinson equation of state and Helmholtz energy equation of state by using critical locus tracing method. The results show that the addition of propylene can increase critical temperature of pure CO
2
and lower its critical pressure.
Pooled data from 2352 hospitalized coronavirus disease 2019 (COVID‐19) patients with viral RNA in feces across 46 studies were analyzed and the pooled prevalence of fecal RNA was 46.8% (95% ...confidence interval CI: 0.383–0.554). The pooled analysis showed that the occurrence of total gastrointestinal (GI) symptoms was 28.5% (95% CI: 0.125–0.44) in COVID‐19 patients with fecal RNA, that of both respiratory and GI symptoms was 21.9% (95% CI: 0.09–0.346), that of only GI symptoms was 19.8% (95% CI: 0.107–0.288), and that of only respiratory symptoms was 50.5%（95% CI: 0.267–0.744). The pooled data showed no significant difference in positive fecal RNA between severe and nonsevere cases (odds ratio = 2.009, p = 0.079, 95% CI: 0.922–4.378). During hospital admission, after samples from the respiratory system tested negative for viral RNA, 55.4% (95% CI: 0.418–0.669) of the patients with positive fecal RNA had persistent shedding of fecal RNA and pooled results from the other 4 studies including 848 discharged patients with nucleic acid‐negative stool samples indicated that the occurrence of repositive stool swabs was 18.1% (95% CI: 0.028–0.335), that of repositive respiratory swabs was 22.8% (95% CI: 0.003–0.452), that of both repositive stool and respiratory swabs was 19.1% (95% CI: 0.019–0.363), and that of only repositive stool swabs was 9.6% (95% CI: 0.010–0.203). The digestive tract may be an important organ involved in COVID‐19 infection and in the excretion of the virus. Because of the potential risk of fecal–oral transmission, giving emphasis on stool swab tests can help increase the detection rate of asymptomatic carriers and reduce missed diagnoses.
Four polysaccharide fractions (P‐1: 71.40%, P‐2: 1.95%, P‐3: 1.14%, P‐4: 1.64%) were isolated from crude Polygonatum sibiricum polysaccharide (PSP), processed by water extraction, ethanol ...precipitation, and further separated with diethylaminoethyl cellulose‐52 anion‐exchange chromatography. Their molecular weights and monosaccharide compositions were characterized by high performance gel chromatography with evaporative light scattering detector and ultraviolet–visible detector. The antioxidant activity of four polysaccharides fractions were assessed by the electron transfer menchanism (DPPH, ferric reducing power, and ABST assays) and chelation of transition metals (Fe2+ and Cu2+ chelation ability). The highest content fraction P‐1 exhibited the lowest antioxidant activity, and the ranking of antioxidant capacity was P‐4 > P‐3 > P‐2 > PSP > P‐1. After processed by microwave‐assisted degradation, the molecular weight of P‐1 was decreased from 2.99 × 105 to 2.33 × 103 Da, while the antioxidant activity of degraded P‐1 was about eightfold higher than natural P‐1. These results indicated that the proposed microwave‐assisted degradation approach was an efficacious methodology to improve their bioactivity by lower the molecular weight of polysaccharides.
Practical Application
This study provided an environmentally friendly, convenient and efficient microwave‐assisted degradation technology to process the neutral polysaccharides from Polygonatum sibiricum. The results could be used for the development and utilization of various plant polysaccharides as a kind of food supplement in our daily life.
Osteoporosis (OP) is distinguished by a reduction in bone mass and degradation of bone micro-structure, frequently resulting in fractures. As the geriatric demographic expands, the incidence of ...affected individuals progressively rises, thereby exerting a significant impact on the quality of life experienced by individuals. The flavonoid compound hesperidin has been subject to investigation regarding its effects on skeletal health, albeit the precise mechanisms through which it operates remain ambiguous. This study utilized network pharmacology to predict the core targets and signaling pathways implicated in the anti-OP properties of hesperidin. Molecular docking and molecular dynamics simulations were employed to confirm the stability of the interaction between hesperidin and the core targets. The effects of hesperidin on osteoblastic cells MC3T3-E1 were assessed using MTT, ELISA, alkaline phosphatase assay, and RT-qPCR techniques. Furthermore, in vivo experiments were conducted to determine the potential protective effects of hesperidin on zebrafish bone formation and oxidative stress response. The results demonstrate that network pharmacology has identified 10 key target points, significantly enriched in the estrogen signaling pathway. Hesperidin exhibits notable promotion of MC3T3-E1 cell proliferation and significantly enhances ALP activity. ELISA measurements indicate an elevation in NO levels and a reduction in IL-6 and TNF-α. Moreover, RT-qPCR analysis consistently reveals that hesperidin significantly modulates the mRNA levels of ESR1, SRC, AKT1, and NOS3 in MC3T3-E1 cells. Hesperidin promotes osteogenesis and reduces oxidative stress in zebrafish. Additionally, we validate the stable and tight binding of hesperidin with ESR1, SRC, AKT1, and NOS3 through molecular dynamics simulations. In conclusion, our comprehensive analysis provides evidence that hesperidin may exert its effects on alleviating OP through the activation of the estrogen signaling pathway via ESR1. This activation leads to the upregulation of SRC, AKT, and eNOS, resulting in an increase in NO levels. Furthermore, hesperidin promotes osteoblast-mediated bone formation and inhibits pro-inflammatory cytokines, thereby alleviating oxidative stress associated with OP.
Cyanide leaching, as a typical traditional method, hardly achieves the cleaner production of gold due to high consumption of auxiliary materials, inefficient production and heavy environmental ...pollution. In this work, stepwise thiourea leaching was used to extract gold and silver from refractory gold concentrate calcine. In the first stage, gold and silver extractions of 84.42% and 44.15% are obtained by thiourea leaching without any additive, respectively, which are further enhanced to 88.71% and 52.65% by adding the additives of lignin sulfonate sodium, urea and iron ion. The spent thiourea can be recycled to leach next batch of calcine after the treatment of replacing gold by iron powder. In the second stage with mechanical activation, higher gold and silver extractions are achieved 96.51% and 70.43%, respectively. Furthermore, a pilot-scale test is carried out to prove the reliability of this technology, which is hopefully adopted in industry to extract gold and silver efficiently and cleanly
•Stepwise thiourea leaching was proposed to extract gold and silver from calcine.•Adding CMN, urea and iron ion could reduce the thiourea consumption.•Adding CMN, urea and iron ion could increase the extraction of gold and silver.•Mechanical activation could increase the extraction of gold and silver.•A pilot-scale test proved the reliability of this technological route.
Colorectal cancer (CRC) is a common gastrointestinal malignancy with high morbidity and fatality. Chemotherapy, as traditional therapy for CRC, has exerted well antitumor effect and greatly improved ...the survival of CRC patients. Nevertheless, chemoresistance is one of the major problems during chemotherapy for CRC and significantly limits the efficacy of the treatment and influences the prognosis of patients. To overcome chemoresistance in CRC, many strategies are being investigated. Here, we review the common and novel measures to combat the resistance, including drug repurposing (nonsteroidal anti‐inflammatory drugs, metformin, dichloroacetate, enalapril, ivermectin, bazedoxifene, melatonin, and S‐adenosylmethionine), gene therapy (ribozymes, RNAi, CRISPR/Cas9, epigenetic therapy, antisense oligonucleotides, and noncoding RNAs), protein inhibitor (EFGR inhibitor, S1PR2 inhibitor, and DNA methyltransferase inhibitor), natural herbal compounds (polyphenols, terpenoids, quinones, alkaloids, and sterols), new drug delivery system (nanocarriers, liposomes, exosomes, and hydrogels), and combination therapy. These common or novel strategies for the reversal of chemoresistance promise to improve the treatment of CRC.
Chemoresistance is the major cause of treatment failure and disease relapse in colorectal cancer (CRC). In addition to some common reversal measures, some novel strategies have sprouted in recent years, including drug repurposing, gene therapy, protein inhibitor, natural herbal compounds, new drug delivery system, and combination therapy, which promise to improve the treatment of CRC.
For high temperature ORC (Organic Rankine Cycle) used in engine waste heat recovery, it's very critical to select a high temperature working fluid. HCs (Hydrocarbons) usually have excellent cycle ...performance, but the flammability limits their practical application. Considering that some retardants can be used to suppress flammability, the paper presents an application of mixtures based on hydrocarbons blending with refrigerant retardants to engine waste heat ORC. Three pure hydrocarbons (cyclopentane, cyclohexane, benzene) and two retardants (R11, R123) are selected for combination. Thermal efficiency and exergy loss are selected as the main objective functions. Based on thermodynamic model, the effects of retardants mass fraction, evaporation temperature and IHE (internal heat exchanger) are investigated. Results show that zeotropic mixtures do have higher thermal efficiency and lower exergy loss than pure fluids, at a certain mixture ratio. There exists the OMR (optimal mixture ratio) for different mixtures, and it changes with the evaporation temperature. When adding IHE to system, cycle performance could be obviously improved, and for benzene/R11 (0.7/0.3), the efficiency growth is about 7.12%∼9.72%. Using it, the maximum thermal efficiency of the system can achieve 16.7%, and minimum exergy loss is only 30.76 kW.
•A theoretical analysis of Organic Rankine Cycle for engine exhaust heat recovery is proposed.•Mixtures based on hydrocarbons as working fluids have been suggested.•Effects of the IHE (internal heat exchanger) on ORC system are investigated.•OMR (Optimal mixture ratio) changes with the evaporation temperature.•Using the system, maximum thermal efficiency can achieve 16.7%.
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