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Two-dimensional topological insulators (2D TIs) have distinct electronic properties that make them attractive for various applications, especially in spintronics. The conductive edge states in 2D TIs are protected from disorder and perturbations and are spin-polarized, which restrict current flow to a single spin orientation. In contrast, topological nodal line semimetals (TNLSM) are distinct from TIs because of the presence of a 1D ring of degeneracy formed from two bands that cross each other along a line in the Brillouin zone. These nodal lines are protected by topology and can be destroyed only by breaking certain symmetry conditions, making them highly resilient to disorder and defects. However, 2D TNLSMs do not possess protected boundary modes, which makes their investigation challenging. There have been several theoretical predictions of 2D TNLSMs, however, experimental realizations are rare. ß-Sn, a metallic allotrope of tin with a superconducting temperature of 3.72 K, may be a candidate for a topological superconductor that can host Majorana Fermions for quantum computing. In this work, single layers of α-Sn and ß-Sn on a Cu(111) substrate are successfully prepared and studied using scanning tunneling microscopy, angle-resolved photoemission spectroscopy, and density functional theory calculations. The lattice and electronic structure undergo a topological transition from 2D topological insulator α-Sn to 2D TNLSM ß-Sn, with two types of nodal lines coexisting in monolayer ß-Sn. Such a realization of two types of nodal lines in one 2D material has not been reported to date. Moreover, we also observed an unexpected phenomenon of freestanding-like electronic structures of ß-Sn/Cu(111), highlighting the potential of ultrathin ß-Sn films as a platform for exploring the electronic properties of 2D TNLSM and topological superconductors, such as few-layer superconducting ß-Sn in lateral contact with topological nodal line single-layer ß-Sn.
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Since two gap superconductivity was discovered in MgB2, research on multigap superconductors has attracted increasing attention because of its intriguing fundamental physics. In MgB2, the Mg atom donates two electrons to the borophene layer, resulting in a stronger gap from the σ band and a weaker gap from the π bond. First-principles calculations demonstrate that the two gap anisotropic superconductivity strongly enhances the transition temperature of MgB2 in comparison with that given by the isotropic model. In this work, we report a three-band (B-σ, B-π, and La-d) two-gap superconductor LaB2 with very high Tc = 30 K by solving the fully anisotropic Migdal-Eliashberg equation. Because of the σ and π-d hybridization on the Fermi surface, the electron-phonon coupling constant λ = 1.5 is significantly larger than the λ = 0.7 of MgB2. Our work paves a new route to enhance the electron-phonon coupling strength of multigap superconductors with d orbitals. On the other hand, our analysis reveals that LaB2 belongs to the weak topological semimetal category, leading to a possible topological superconductor with the highest Tc to date. Moreover, upon applying pressure and/or doping, the topology is tunable between weak and strong with Tc varying from 15 to 30 K, opening up a flexible platform for manipulating topological superconductors.
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Ecological civilization construction is China's national development strategy, and improving the urban eco-environmental quality is the key to accelerating this strategy, while the high-speed rail (HSR) opening is an important factor affecting the urban eco-environmental quality. Using panel data of 290 cities in China from 2004 to 2020, this study explores the impact of HSR opening on urban eco-environmental quality and its heterogeneity from the perspective of direct impact and interaction between HSR connected cities. Compared with cities without HSR service, the eco-environmental quality of cities with HSR service has significantly increased by 0.023 standard deviations, which is about 4.11% of the total change in urban eco-environmental quality in the same period. Second, there is an inverted U-shaped relationship between eco-environmental quality and urban space expansion. Third, the impact of HSR on eco-environmental quality is heterogeneous, mainly manifested in different cities and urban agglomerations. It means that the government should focus on the differences in the economic foundation and development characteristics of various regions, steadily push forward the construction and operation of the HSR, and speed up the renovation of existing lines to help the green development of cities. The research results provide a policy basis for the government to handle the relationship between infrastructure construction and eco-environmental quality, and effectively promote green sustainable development.
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Civilização , Governo , China , Cidades , Orientação EspacialRESUMO
N6-methyladenosine (m6A) has been increasingly recognized as a new and important regulator of gene expression. To date, transcriptome-wide m6A detection primarily relies on well-established methods using next-generation sequencing (NGS) platform. However, direct RNA sequencing (DRS) using the Oxford Nanopore Technologies (ONT) platform has recently emerged as a promising alternative method to study m6A. While multiple computational tools are being developed to facilitate the direct detection of nucleotide modifications, little is known about the capabilities and limitations of these tools. Here, we systematically compare ten tools used for mapping m6A from ONT DRS data. We find that most tools present a trade-off between precision and recall, and integrating results from multiple tools greatly improve performance. Using a negative control could improve precision by subtracting certain intrinsic bias. We also observed variation in detection capabilities and quantitative information among motifs, and identified sequencing depth and m6A stoichiometry as potential factors affecting performance. Our study provides insight into the computational tools currently used for mapping m6A based on ONT DRS data and highlights the potential for further improving these tools, which may serve as the basis for future research.
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Nanoporos , RNA , RNA/genética , Transcriptoma , Adenosina/metabolismo , Análise de Sequência de RNA/métodos , Sequenciamento de Nucleotídeos em Larga Escala/métodosRESUMO
The conversion of dinitrogen to more useful and reactive molecules has been the focus of intense research by chemists. In contrast to reductive N2 fixation, direct oxidation of N2 by O2 to nitric oxide under mild conditions via a thermochemical process is extremely challenging. Herein, we report the first example of N2 and O2 activation and coupling under thermochemical conditions through the remarkable ability of Y2BO+ to react with one N2 and two O2 molecules. Detailed mechanistic studies using mass spectrometry and quantum chemical calculations revealed that the N2 activation by Y2BO+ is facilitated by the double aromatic character of the Y2BON2+ intermediate. Subsequent oxidation with O2 releases NO in a dearomatization process driven by the formation of stronger Y-O bonds over the Y-N bonds. Our findings represent the first example of N2 and O2 activation and coupling under thermochemical conditions at room temperature, providing a novel strategy for small-molecule activation.
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The activation and functionalization of dinitrogen with carbon dioxide into useful chemicals containing C-N bonds are significant research projects but highly challenging. Herein, we report that N2 molecules are dissociated by heterobimetallic CuNb- anions assisted by surface plasma radiation, leading to the formation of CuNbN2- anions; the CuNbN2- anions can further react with CO2 to generate products NCO- with one C-N bond and NbO2NCN- with two C-N bonds under thermal collision conditions. For the activation of dinitrogen, the plasma atmosphere is conducive to the dissociation of the NîN bond, which renders the coupling reactions of N2 and CO2 molecules easier to proceed. This is the first report of coupling of N2 and CO2 to generate C-N bonds by making good use of the plasma effect to assist in the activation of N2 molecules. This new strategy with the assistance of plasma provides a practicable route to construct C-N bonds by directly using N2 and CO2 at room temperature.
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Environmental protection and innovation performance are key issues that affect the sustainable development and value growth of cities. Using data of 272 prefecture-level cities during 2002-2016 and 2,169 listed companies, and the air ventilation coefficient and government environmental regulations, as the instrumental variables for PM2.5 concentrations, this paper applies two-stage OLS (2SLS) to investigate how air pollution affects China's technological innovation and its realization mechanism. The results indicate that the rise in air pollution significantly inhibits the technological innovation level of regions as a whole as well as individual enterprises. When considering the spatial effect of the spread of PM2.5 concentrations, due to positive spillover effects on innovation activities, the spread of air pollution has negative impacts on technological innovation activities in surrounding cities. Human capital and labour costs are important channels through which air pollution influences China's technological innovation. The implementation of pilot carbon trading policies can effectively reduce air pollution and then contribute to the achievement of the goals of the green growth strategy.
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Poluentes Atmosféricos , Poluição do Ar , Poluentes Atmosféricos/análise , Poluição do Ar/análise , Carbono , China , Cidades , Poluição Ambiental , Humanos , Material Particulado/análiseRESUMO
Aim To investigate the protective effect of mGluR5 activated by VU0360172 on germinal matrix hemorrhage in neonatal rats.Methods Seven day- old SD rats were randomly divided into Sham, GMH, and low-, medium-, and high-dose groups.The model was established by intracerebral injection of collagenase W-S.Then three doses of VU0360172 were injected intraperitoneal
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The activation of carbon dioxide (CO2) mediated by NbBN2- cluster anions under the conditions of thermal collision has been investigated by time-of-flight mass spectrometry combined with density functional theory calculations. Two CîO double bonds in the CO2 molecule are completely broken and two C-N bonds are further generated to form the novel molecule NCNBO-. To the best of our knowledge, this new molecule is synthesized and reported for the first time. In addition, one oxygen atom transfer channel produces another product, NbBN2O-. Both of the Nb and B atoms in NbBN2- donate electrons to reduce CO2, and the carbon atom originating from CO2 serves as an electron reservoir. The reaction of NbB- with N2 was also investigated theoretically, and the formation of NbBN2- from this reaction is thermodynamically and kinetically quite favorable, indicating that NCNBO- might be produced from the coupling of N2 and CO2 mediated by NbB- anions.
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Dinitrogen activation and transformation at room temperature is a goal that has been long sought after. Despite that, it remains underdeveloped due to being a challenging research area and the need for a better mechanistic understanding. Herein, we report that well-defined NbB3O2- gas-phase clusters can activate one N2 molecule and generate the products B3N2O- and B3N2O2-, as applying mass spectrometry and theoretical calculations. This unusual N2 activation reaction results from the different functions of the Nb and B3O2 moieties in NbB3O2-. Theoretical calculations suggest that a catalytic cycle can be completed by the recovery of NbB3O2-, which is achieved through the reactions of Nb and NbO with B3O2- and B3O-, respectively. This is the first example of N2 efficient transformation at a monometallic cluster, and this method for generating dual active sites by designing proper ligands may open the way toward the development of more effective N2 fixation and functionalization methodologies.
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Among various energy storage and conversion materials, functionalized natural clays display significant potentials as electrodes, electrolytes, separators, and nanofillers in energy storage and conversion devices. Natural clays have porous structures, tunable specific surface areas, remarkable thermal and mechanical stabilities, abundant reserves, and cost-effectiveness. In addition, natural clays deliver the advantages of high ionic conductivity and hydrophilicity, which are beneficial properties for solid-state electrolytes. This review article provides an overview toward the recent advancements in natural clay-based energy materials. First, it comprehensively summarizes the structure, classification, and chemical modification methods of natural clays to make them suitable in energy storage and conversion devices. Then, the particular attention is focused on the application of clays in the fields of lithium-ion batteries, lithium-sulfur batteries, zinc-ion batteries, chloride-ion batteries, supercapacitors, solar cells, and fuel cells. Finally, the possible future research directions are provided for natural clays as energy materials. This review aims at facilitating the rapid developments of natural clay-based energy materials through a fruitful discussion from inorganic and materials chemistry aspects, and also promotes the broad sphere of clay-based materials for other utilization, such as effluent treatment, heavy metal removal, and environmental remediation.
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In light of the current energy requirements, the conversion of CO2 and N2 into useful C-N bond-containing products under mild conditions has become an area of intense research. However, the inert nature of N2 and CO2 renders their coupling extremely challenging. Herein, nitrogen and carbon atoms originating from N2 and CO2, respectively, are fixed sequentially by NbH2- anions in the gas phase at room temperature. Isocyanate and NbO2CN- anions were formed under thermal collision conditions, thus achieving the formation of new C-N bonds directly from simple N2 and CO2. The anion structures and reaction details were studied by mass spectrometry, photoelectron spectroscopy, and quantum chemical calculations. A novel N2 activation mode (metal-ligand activation, MLA) and a related mechanism for constructing C-N bonds mediated by a single non-noble metal atom are proposed. In this MLA mode, the C atom originating from CO2 serves as an electron reservoir to accept and donate electrons.
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OBJECTIVE: To observe the clinical effect of high suspension and low incision (HSLI) surgery on mixed haemorrhoids, compared with Milligan-Morgan haemorrhoidectomy. METHODS: A multi-centre, randomized, single-blind, non-inferiority clinical trial was performed. Participants with mixed haemorrhoids from Xiyuan Hospital of China Academy of Chinese Medical Sciences, Beijing Rectum Hospital, Air Force Medical Center of People's Liberation Army of China, and Puyang Hospital of Traditional Chinese Medicine were enrolled from September 2016 to March 2018. By using a blocked randomization scheme, participants were assigned to two groups. The experimental group was treated with HSLI, while the control group was treated with Milligan-Morgan haemorrhoidectomy. The primary outcome was the clinical effect evaluated at 12 weeks after operation. The secondary outcomes included the number of haemorrhoids treated during the operation, pain scores, use of analgesics, postoperative oedema, wound healing, incidence of anal stenosis, anorectal manometry after operation, as well as surgical duration, length of stay and total hospitalization expenses. A safety evaluation was also conducted. RESULTS: In total, 246 eligible participants were enrolled, with 123 cases in each group. There was no significant difference in the clinical effect between the two groups (100.00% vs. 99.19%, P>0.05). Compared with the control group, the number of external haemorrhoids treated during the operation and the pain scores after operation were significantly reduced in the experimental group (P<0.05 or P<0.01); the patient number with wound healing at 2 weeks after operation and the functional length of anal canal at 12 weeks after operation were significantly increased in the experimental group (P<0.05). There was no significant difference in the incidence of anal stenosis, the numbers of patients using analgesics and patients with postoperative oedema between the two groups after operation (P>0.05). The surgical duration and length of stay in the experimental group were significantly longer than those in the control group, and the total hospitalization expense was significantly higher than that in the control group (all P<0.05). No adverse events were reported in either group during the whole trial or follow-up period. CONCLUSION: HSLI had the advantages of preserving the skin of anal canal completely, alleviating postsurgical pain and promoting rapid recovery after operation. (Registration No. ChiCTR1900022883).
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Procedimentos Cirúrgicos do Sistema Digestório , Hemorroidas , Hemorroidas/cirurgia , Humanos , Ligadura , Medicina Tradicional Chinesa , Método Simples-Cego , Resultado do TratamentoRESUMO
Objective:To evaluate the effectiveness and safety of preemptive nasogastric tube placement for improving nutritional status and clinical outcomes in hospitalized infants with congenital heart disease.Methods:Children from 0 to 12 months with congenital heart disease hospitalized in cardiovascular center of Children's Hospital of Fudan University from February to July 2018 were selected as control group through continuous sampling. Children hospitalized were selected from September 2018 to February 2019 as intervention group. The control group followed the current feeding method, the intervention group used preemptive nasogastric tube placement. The nutritional indicators, feeding indicators and clinical outcomes of the two groups were compared to evaluate the intervention effect.Results:The serum albumin and prealbumin of the children in the intervention group were (36.81±4.59) g/L and (162.74±48.17) g/L, which were higher than those in the control group (34.80±5.21) g/L and (142.98± 33.96) g/L, the difference between the two groups was statistically significant ( t values were -2.721, -3.169, both P<0.05); the daily enteral intake, calorie intake and single enteral calorie intake of children in the intervention group were (124.93±27.97) ml·kg -1·d -1, (376.48±88.53) kj·kg -1·d -1, (48.39±9.13) kj·kg -1·time -1, higher than the control group (114.74±30.63) ml·kg -1·d -1, (330.01±90.75) kj·kg -1·d -1, (44.24±13.31) kj·kg -1·time -1, the difference between the two groups was statistically significant ( t values were -2.511, -3.750, -2.382, all P<0.05). the incidence of feeding difficulties in the intervention group was 4.95% (5/101) lower than 14.68% (16/109) of the control group, the difference between the two groups was statistically significant ( χ2 value was 5.513, P<0.05); the proportion of children in the intervention group reaching the target feeding amount when discharged from the hospital was 97.03% (98/101), higher than 84.40% (92/109) of the control group, the difference between the two groups was statistically significant ( χ2 value was 9.699, P<0.05). Conclusions:Preemptive nasogastric tube placement is safety and effectively for patients with congenital heart disease in clinical infants. but it still needs a large sample for a long time to confirm its effectiveness.
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OBJECTIVE@#To observe the clinical effect of high suspension and low incision (HSLI) surgery on mixed haemorrhoids, compared with Milligan-Morgan haemorrhoidectomy.@*METHODS@#A multi-centre, randomized, single-blind, non-inferiority clinical trial was performed. Participants with mixed haemorrhoids from Xiyuan Hospital of China Academy of Chinese Medical Sciences, Beijing Rectum Hospital, Air Force Medical Center of People's Liberation Army of China, and Puyang Hospital of Traditional Chinese Medicine were enrolled from September 2016 to March 2018. By using a blocked randomization scheme, participants were assigned to two groups. The experimental group was treated with HSLI, while the control group was treated with Milligan-Morgan haemorrhoidectomy. The primary outcome was the clinical effect evaluated at 12 weeks after operation. The secondary outcomes included the number of haemorrhoids treated during the operation, pain scores, use of analgesics, postoperative oedema, wound healing, incidence of anal stenosis, anorectal manometry after operation, as well as surgical duration, length of stay and total hospitalization expenses. A safety evaluation was also conducted.@*RESULTS@#In total, 246 eligible participants were enrolled, with 123 cases in each group. There was no significant difference in the clinical effect between the two groups (100.00% vs. 99.19%, P>0.05). Compared with the control group, the number of external haemorrhoids treated during the operation and the pain scores after operation were significantly reduced in the experimental group (P0.05). The surgical duration and length of stay in the experimental group were significantly longer than those in the control group, and the total hospitalization expense was significantly higher than that in the control group (all P<0.05). No adverse events were reported in either group during the whole trial or follow-up period.@*CONCLUSION@#HSLI had the advantages of preserving the skin of anal canal completely, alleviating postsurgical pain and promoting rapid recovery after operation. (Registration No. ChiCTR1900022883).
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Objective:To compare and explore the effects of needling acupoints at different nerve segmentson the oxytocin (OT) neurons in the paraventricular nucleus of hypothalamus (PVN) and the intragastric pressure, and discuss the possible mechanisms. Methods: Thirty-two healthy adult Sprague-Dawley (SD) rats were numbered and divided into 4 groups according to the random number table, a Zusanli (ST 36) group, a Neiguan (PC 6) group, a Weishu (BL 21) group and a control group, with 8 rats in each group. Except the control group, rats in the other three groups received acupuncture at the corresponding acupoints. To observe the differences in double-labeled OT neurons and c-fos neurons of the hypothalamic PVN and the intragastric pressure after acupuncture among the three groups of needling acupoints at different nerve segments. Results:Compared with the control group, the numbers of double-labeled cells in the PVN of the Zusanli (ST 36) group and the Neiguan (PC 6) group decreased significantly, while the intragastric pressure increased significantly (allP<0.05), and the inter-group differences were statistically significant (P<0.05). The intragastric pressure in the Weishu (BL 21) group decreased significantly, and the inter-group difference was statistically significant (P<0.05). Compared with the Weishu (BL 21) group, the numbers of OT/c-fos double-labeled cells in PVN of the Zusanli (ST 36) group and the Neiguan (PC 6) group decreased significantly, and the intragastric pressure increased significantly, the inter-group differences were statistically significant (allP<0.01). Conclusion:Acupoints at different nerve segments have different regulation effects on intragastric pressure. The difference may be related to the different nerve conduction pathways by acupoints at different nerve segments in regulating the intragastric pressure. The PVN may be one common integration center for the regulation of gastric function in the three acupoints [Zusanli (ST 36), Neiguan (PC 6) and Weishu (BL 21)] at different nerve segments.
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Objective To disscus the applicability of three surveillance methods for Aedes albopictus in dengue risk indication. Methods Larval and adult mosquito surveillance were conducted in two villages of Guangzhou by using three vector monitoring methods. Meteorological data and dengue cases were obtained in the same period. Results The population dynamics of larvae and adult mosquitoes were affected by temperature and their overall trend was consistent, but there were differences between the abundance of larvae and adult mosquitoes. From December to February the next year, Breteau index(BI) ranged from 5.66 to 24.53 with a risk of level 1 to 3 for dengue fever, while the mosquito and oviposition positive index(MOI) and adult-mosquito density index(ADI) were 0 to 4.00 and 0 to 1 per man-hour, respectively, indicating no risk for dengue fever. In March, compared with BI which indicated a risk of level 3, MOI were 2.13 and 3.77, respectively, representing for no risk. ADI were 4 to 6 per man-hour, indicating a risk of level 1 and level 2, respectively. After April, the dengue risk level reflected by each indicator became to be consistent. Conclusions The risk of dengue fever indicated by BI is always higher than or equal to the risk indicated by the other two. Compared with BI, MOI and ADI are more sensitively in reflecting the activity of Ae. albopictus.
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Objective@#To explore the clinical features, the serotype distribution and drug resistance of the isolates in patient with invasive pneumococcal disease (IPD).@*Methods@#By retrieving the laboratory information system in 18 children′s hospitals from 2012 to 2017, the children with IPD were enrolled. Streptococcus pneumoniae (Spn) must be isolated from the sterile sites (blood, cerebrospinal fluid, hydrothorax and joint effusion etc.). The clinical characteristics, serotype, drug resistance, treatment and prognosis were reviewed and analyzed. According to the telephone follow up results, the patients were divided into death group and recovered group. The index as an independent risk factor of mortality was demonstrated by multivariate logistic regression analysis.@*Results@#There were 1 138 children with IPD, including 684 male and 454 female. The proportion of male to female was 1.5∶1. The age ranged from one day to 16 years. The median age was 1 year 3 month. The majority was under 5 years of age (89.3%, n= 1 016), especially under 2 years of age (61.9%, n=704). In all cases, 88.2% (n=1 004) were community acquired infection. The infections included meningitis (n=446, 39.2%), pneumonia with bacteremia (n=339, 29.8%), and bacteremia without focus (n=232, 20.4%). Underlying diseases were found in 242 cases (21.3%). Co-infections were determined in 62 cases (5.4%) with mycoplasma, 27 cases (2.4%) with adenovirus and 34 cases with influenza virus (3.0%). The penicillin insensitivity (PNSP) rates in meningitis and non-meningitis isolates were 69.5% (276/397) and 35.9% (221/615), respectively. There were 81 strains serotyped, in which 93.8% (76/81) were covered by 13-valent protein-polysaccharide conjugate vaccine (PCV13). In the 965 patients who were followed up by phone call, 156 cases (16.2%) were confirmed dead. The independent risk factors for the death were under 2 years of age (OR=2.143, 95%CI 1.284-3.577, P=0.004), meningitis (OR=3.066, 95%CI 1.852-5.074, P<0.01), underlying disease (OR=4.801, 95%CI 2.953-7.804, P<0.01), septic shock(OR=3.542, 95%CI 1.829-6.859, P<0.01), disseminated intravascular coagulation (DIC) (OR=4.150, 95%CI 1.468-11.733, P=0.007), multiple organ failure (OR=12.693, 95%CI 6.623-24.325, P<0.01) and complications of central nervous system (OR=1.975, 95%CI 1.144-3.410, P=0.015).@*Conclusions@#Most children with IPD were under 5 years of age, having underlying diseases and acquired the infection in community. The independent risk factors for death were under two years old, meningitis, underlying diseases and multiple organ failure. The problem of drug resistance was severe. The universal immunization of PCV13 would be effective to prevent IPD in Chinese children.
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Aim To explore the protective effects of naringin on hypoxic ischemic brain injury in neonatal rats and its mechanism. Methods Ninety-six healthy 7-day neonatal SD rats were randomly divided into sham operation group, hypoxic-ischemic brain damage group (HIBD group),HIBD with low-dose naringenin group(50 mg·kg-1, NG-L) and HIBD with high-dose naringenin group(100 mg·kg-1,NG-H). Neu-rological deficit, HE staining and brain water content were measured 48h after operation. Immunoblotting was used to detect the expressions of NOD2,RIP2 and NF-κB. Enzyme linked immunosorbent assay(ELISA) method was adopted to detect TNF-α and IL-1β ex-pression. Results Compared with HIBD group, the neurological deficit score decreased, the pathological damage was reduced, and the water content of brain tissues markedly decreased by naringenin(50,100 mg ·kg-1) treatment(P<0.05). Western blot revealed the down-regulation of NOD2,RIP2 and NF-κB by na-ringenin (50,100mg·kg-1) treatment (P<0.05). The content of TNF-α and IL-1β in brain tissues was lower than that of HIBD group (P <0.05). Conclu-sion Naringenin is likely to exert a protective role in neonatal rats of hypoxic ischemic brain injury perhaps through decreasing the expression of NOD2, RIP2 and NF-κB,and reducing the secretion of TNF-α and IL-1β.