Electron correlations and superconductivity in La3_3Ni2_2O7_7 under pressure tuning

Motivated by the recent discovery of superconductivity in La$_3$Ni$_2$O$_7$ under pressure, we discuss the basic ingredients of a model that captures its microscopic physics under pressure tuning. We anchor our description in terms of the spectroscopic evidence of strong correlations in this system. In a bilayer Hubbard model including the Ni $3d$ $x^2-y^2$ and $z^2$ orbitals, we show the ground state of the model crosses over from a low-spin $S=1/2$ state to a high-spin $S=3/2$ state. In the high-spin state, the two $x^2-y^2$ and the bonding $z^2$ orbitals are all close to half-filling, which promotes a strong orbital selectivity in a broad crossover regime of the phase diagram pertinent to the system. Based on these results, we construct an effective multiorbital $t$-$J$ model to describe the superconductivity of the system, and find the leading pairing channel to be an intraorbital spin singlet with a competition between the extended $s$-wave and $d_{x^2-y^2}$ symmetries. Our results highlight the role of strong multiorbital correlation effects in driving the superconductivity of La$_3$Ni$_2$O$_7$.Comment: 5.5+4 pages, 4+3 figures, 2 tables, updated version with supplemental materia

Protopanaxadiol and Protopanaxatriol-Type Saponins Ameliorate Glucose and Lipid Metabolism in Type 2 Diabetes Mellitus in High-Fat Diet/Streptozocin-Induced Mice

Ginsenoside is a major active component of ginseng, which exhibits various pharmacological properties such as hepatoprotection, tumor suppression and diabetes resistance. In this study, the anti-diabetic effects of protopanaxadiol (PPD) and protopanaxatriol (PPT)-type saponins were explored and compared in high-fat diet/streptozocin-induced type 2 diabetes mellitus (T2DM) mice. Our results showed that low or high dose (50 mg/kg bodyweight or 150 mg/kg bodyweight) PPD and PPT significantly reduced fasting blood glucose, improved glucose tolerance and insulin resistance in T2DM mice. PPD and PPT also regulated serum lipid-related markers such as reduced total cholesterol (TC), triglyceride (TG), and low-density lipoprotein cholesterol in T2DM mice. In addition, PPD and PPT dramatically ameliorated the inflammatory responses by suppressing the secretion of pro-inflammatory cytokines like tumor necrosis factor-alpha and interleukin-6 in serum level and gene expression in liver level, and improved the antioxidant capacity by increasing the superoxide dismutase and decreasing malondialdehyde levels in the serum of T2DM mice. Moreover, the anti-diabetic effect of PPD and PPT appeared to be partially mediated by the suppression of hepatic metabolism genes expression such as peroxisome proliferator-activated receptor gamma coactivator 1-alpha, phosphoenolpyruvate carboxykinase, and glucose-6-phosphatase, as well as facilitating lipid metabolism genes expression such as microsomal TG transfer protein in the liver tissues of T2DM mice. Taken together, our results indicated that PPD and PPT might potentially act as natural anti-diabetic compounds to be used for preventing and treating the T2DM and its complications in the future

Lifted flame property and interchangeability of natural gas on partially premixed gas burners

The relationship between lifted flames and burner head temperature of partially premixed gas burners supplied by various natural gas sources was investigated, and the application of AGA(American Gas Association) lifting limit for Chinese domestic gas burners was studied. Results showed that lifted flames became more seriously with the burner head temperature decreasing, also with the increase of lift height of flames, it would lead to reduce the burner head temperature, eventually the burner head would reach the thermal equilibrium state which maintained stable flames and temperature. The lifting limit curve of partially premixed gas burners was only one under the same gas source, and it only depended on the burner structures and gas source characteristics, but nothing to do with the burner head temperature. The gas source with lower Wobbe index and calorific value made the burner appearing lifted flame more easily. Comparing with the experiment results and AGA lifting index prediction, it suggested that the limits of AGA lifting index IL≤ 1.10 should be change into IL≤ 1.05 using in China. Keywords: Partially premixed gas burners, Lifted flames, Natural gas, AGA lifting inde

Experimental Study of the Influence of Natural Gas Constituents on CO Emission from Chinese Gas Cooker

In China, it has become a more common practice to introduce natural gases from different sources into the same distribution system to improve supply security and reliability. Variable gas constituents may cause a negative impact on the performance of domestic gas appliances. This paper aims to study the CO emission of a Chinese gas cooker under different constituents of natural gas. A typical Chinese gas cooker with two burners, each of which has a nominal heat input of 3.8 kW, was selected. One of the burners was modified to a forced-mixed mode to replace primary air injection. Within operational ranges corresponding to the permissible Wobbe index—namely, primary air coefficients and heat inputs—the equivalence between original gas and the CH4/C3H8/N2 three-component mixture in terms of CO emission was experimentally validated. Then, different three-component mixtures were input into the other unmodified burner, which operates under injected primary air, to investigate how the CO emission changed with different gas constituents. It was found that the CO emission of a natural gas and a CH4/C3H8/N2 three-component mixture, in terms of CO emission, were equivalent. The combination of the two indexes, W and PN, can describe the CO emission from a gas cooker accurately. By means of a three-component mixture, the empirical formula, which can correlate CO and the gas property parameters, was proposed. A set of equal-CO lines was revealed for a given initial primary air adjustment. Finally, a feasible approach to manage gas quality management in China was put forward, and the conclusion can help control the CO emission of gas cookers and improve indoor air quality

Combustion performance of domestic gas cookers with swirling strip-port and normal round-port on various natural gas compositions

This document aims to assess the different performance of swirling strip-port and normal round-port domestic gas cookers with gas property fluctuation and propose suitable structure design parameter for both port types. Comparing with normal round-port gas cookers, swirling strip-port samples are not advantage on aspects of thermal efficiency and CO emission, but in term of NOx emission it performs very well which can effectively control NOx emission in a suitable range and improve gas cooker′s adaptive capacity, when natural gas is interchanged. It is easier to qualify CO emission with low NOx emission for swirling strip-port gas cookers, though it will sacrifice a part of thermal efficiency, while normal round-port gas cookers are easier to qualify CO emission with high thermal efficiency. The burner head design structure parameters of normal round-port gas cookers which can well adapt natural gas interchange are port thermal intensity in 7.2–8.4 W/mm2 and structure factor ε in 30–40, as well as swirling strip-port gas cookers are port thermal intensity in 8.0–11.5 W/mm2 with structure factor ε in 35–45. Keywords: Domestic gas cooker, Swirling strip-port, Normal round-port, Thermal efficiency, Emission, Natural gas interchang

Research collaboration in health management research communities

BACKGROUND: This study uses scientometrics methodology to reveal the status quo and emerging issues of collaboration in health management. METHODS: We searched all the articles with the keyword “health management” in the period 1999–2011 in Web of Knowledge, then 3067 articles were found. Methods such as Social network analysis (SNA), co-authorship, co-word analysis were used in this study. RESULTS: Analysis of the past 13 years of research in the field of health management indicates that, whether the production of scientific research, or authors, institutions and scientific research collaboration at the national level, collaboration behavior has been growing steadily across all collaboration types. However, the international scientific research cooperation about health management study between countries needs to be further encouraged. 17 researchers can be seen as the academic leaders in this field. 37 research institutions play a vital role in the information dissemination and resources control in health management. The component analysis found that 22 research groups can be regarded as the backbone in this field. The 8 institution groups consisting of 33 institutions form the core of this field. USA, UK and Australia lie in the center by cohesive subgroup analysis; Based on keywords analysis, 44 keywords with high frequency such as care, disease, system and model were involved in the health management field. CONCLUSIONS: This study demonstrates that although it is growing steadily, collaboration behavior about health management study needs to be enhanced, especially between different institutions or countries/regions, which would promote the progress and internationalization of health management. Besides, researchers should pay attention to the cooperation of representative scholars and institutions, as well as the hot areas of research, because their experience would help us promote the research development of our nation

Ginsenoside Rh4 Suppresses Metastasis of Esophageal Cancer and Expression of c-Myc via Targeting the Wnt/β-Catenin Signaling Pathway

The metastasis of esophageal squamous cell carcinoma (ESCC) is a leading cause of death worldwide, however, it has a poor prognosis. Ginsenoside Rh4 is a rare saponin that has been shown to have potential antitumor effectiveness in ESCC. However, the utility of Rh4 in ESCC metastasis and its undiscovered mode of action has not yet been explored. In this study, we found that Rh4 could inhibit ESCC metastasis by regulating the Wnt/β-catenin signaling pathway and the level of c-Myc, which is an important transcription factor in cancer. In in vitro experiments, Rh4 could inhibit the migration and invasion of ESCC cells without affecting cell viability. In in vivo experiments, Rh4 restrained ESCC metastasis to the lymph nodes and lungs via the suppression of epithelial-mesenchymal transition (EMT). The Wnt agonist HLY78 promoted EMT and migration of ESCC cells, whereas treatment of Rh4 can attenuate the promotion effect of HLY78. The siRNA knocking out c-Myc can also significantly reduce the expression of EMT-related marker proteins. This study illustrates a new concept for further research on the mechanism of Rh4 in ESCC

Inhibitory Effect of pH-Responsive Nanogel Encapsulating Ginsenoside CK against Lung Cancer

Ginsenoside CK is one of the intestinal bacterial metabolites of ginsenoside prototype saponins, such as ginsenoside Rb1, Rb2, Rc, and Rd. Poor water solubility and low bioavailability have limited its application. The nanogel carriers could specifically deliver hydrophobic drugs to cancer cells. Therefore, in this study, a nanogel was constructed by the formation of Schiff base bonds between hydrazide-modified carboxymethyl cellulose (CMC-NH2) and aldehyde-modified β-cyclodextrin (β-CD-CHO). A water-in-oil reverse microemulsion method was utilized to encapsulate ginsenoside CK via the hydrophobic cavity of β-CD. β-CD-CHO with a unique hydrophobic cavity carried out efficient encapsulation of CK, and the drug loading and encapsulation efficiency were 16.4% and 70.9%, respectively. The drug release of CK-loaded nanogels (CK-Ngs) in vitro was investigated in different pH environments, and the results showed that the cumulative release rate at pH 5.8 was 85.5% after 140 h. The methylthiazolyldiphenyl-tetrazolium bromide (MTT) toxicity analysis indicated that the survival rates of A549 cells in CK-Ngs at 96 h was 2.98% compared to that of CK (11.34%). In vivo animal experiments exhibited that the inhibitory rates of CK-Ngs against tumor volume was 73.8%, which was higher than that of CK (66.1%). Collectively, the pH-responsive nanogel prepared herein could be considered as a potential nanocarrier for CK to improve its antitumor effects against lung cancer