The anthocyanin formation of purple leaf is associated with the activation of LfiHY5 and LfiMYB75 in crape myrtle

Purple-leafed plants not only have a higher resistance to biotic and abiotic stresses,but also have higher ornamental value.Anthocyanins are vital for leaf color formation,growth and development of purple leaves.However,the molecular mechanism underlying purple leaf formation in Lagerstroemia indica remains unclear.Metabolomic and transcriptomic analysis of purple-leafed cultivar‘Ebony Embers’and greenleafed cultivar‘Arapahoe’showed that the high expression of anthocyanin structure genes induced hyperaccumulation of cyanidin and pelargonidin derivatives,making the leaves purple.LfiHY5,LfiMYB75 and LfibHLH1 were identified using correlation analysis and weighted gene co-expression network analysis.In‘Arapahoe’‘Ebony Embers’population,LfiHY5 and LfiMYB75 showed significant positive correlation with leaf anthocyanin content.Transient expression of LfiMYB75 and LfiHY5 in tobacco and purple-leafed crape myrtle indicated that the two genes activated anthocyanin synthesis.Yeast two-hybrid analysis showed that LfiMYB75 and LfibHLH1 could form a complex that enhanced anthocyanin synthesis.Yeast monohybrid and dual-luciferase assays confirmed that LfiHY5 activated the expression of LfiMYB75,to activate the transcription of anthocyanin structural genes LfiCHS and LfiANS.Moreover,there were three alleles of LfiHY5 in crape myrtle,and the different sequences had different activation effects on LfiMYB75.In conclusion,the results showed that LfiHY5 led to upregulate the transcription of LfiMYB75,and LfiMYB75 formed a complex with LfibHLH1,which increased the transcription level of LfiCHS and LfiANS to affect anthocyanin synthesis in crape myrtle.

Prospect of Detecting Magnetic Fields from Strong-magnetized Binary Neutron Stars

Binary neutron star mergers are unique sources of gravitational waves in multi-messenger astronomy.The inspira phase of binary neutron stars can emit gravitational waves as chirp signals.The present waveform models o gravitational waves only considered the gravitational interaction.In this paper,we derive the waveform of th gravitational wave signal taking into account the presence of magnetic fields.We found that the electromagneti interaction and radiation can introduce different frequency-dependent power laws for both the amplitude and frequency of the gravitational wave.We show from the results of the Fisher information matrix that the third generation observation may detect magnetic dipole moments if the magnetic field is~10^(17)G.

杭州地区2012~2018年耐甲氧西林金黄色葡萄球菌的分子流行病学特征及其变化趋势

耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus,MRSA)是威胁全球的公共卫生问题,给社会和患者造成严重的安全威胁,因此明确MRSA耐药性和时空分布的多态性对于其感染的诊治和防控至关重要。本研究通过收集本院162株MRSA菌株,将所有菌株根据标准区分为社区获得性(community-associated)MRSA(CA-MRSA)和医院获得性(hospital-associated)MRSA(HA-MRSA),利用聚合酶链式反应(polymerase chain reaction,PCR)测定MRSA菌株的多位点序列分型(multilocus sequence typing,MLST),葡萄球菌盒式染色体序列(staphylococcal chromosome cassette mec,SCCmec)、葡萄球菌A蛋白(staphylococcal protein A,spa)基因多态性,以及杀白细胞毒素(Panton-Valentine leucocidin,PVL),分析了杭州地区不同年份(2012~2018年)MRSA菌株的分子特征。结果共发现16种ST型和30种spa型。ST型以ST5型为主(96/162,59.3%),spa分型以t311型为主(83/162,51.2%)。发现5种SCCmec分型,以SCCmec II型最为常见(101/162,61.7%),ST5-II-t311是本地区的第一优势MRSA克隆。2014~2018年,ST5型MRSA的患病率逐渐下降,而ST59型MRSA的患病率上升。同时,本研究检出家畜相关耐甲氧西林金黄色葡萄球菌(livestock-associated methicillin-resistant Staphylococcus aureus,LA-MRSA)ST398和ST9。PVL基因阳性MRSA菌株共28株(28/162,17.3%),最常见的PVL阳性克隆是ST59-IVa-t437。CA-MRSA与HA-MRSA相比,ST型为ST5的比例较低(9.1%vs 67.1%,P=0.000),ST59的比例较高(63.6%vs 11.4%,P=0.000),且CA-MRSA携带PVL阳性基因的可能性更高(36.4%vs 14.3%,P=0.028)。上述结果表明,MRSA的分子类型越来越多样化,ST5-II-t311是本地区MRSA的优势克隆,但在2014~2018年呈下降趋势,而社区相关性克隆菌株ST59型MRSA在2014~2018年呈逐年上升趋势。

Leydig cell transplantation restores androgen production in surgically castrated prepubertal rats

Prepubertal testicular dysfunction and the subsequent development of hypogonadism affects an estimated one in 200 children worldwide. As the testosterone levels are dynamic during development and puberty, traditional hormone treatment regimens are often inadequate, thereby leaving associated physiological conditions unresolved. Therefore, we have investigated the potential therapeutic effect of mature Leydig cell transplantation for the treatment of prepubertal primary hypogonadism through the use of a surgically induced hypogonadistic rat model system. In the experiment, Leydig cells were surgically isolated from mature Sprague-Dawley rats and transplanted into prepubertal recipients. Serum testosterone levels and microscopic analysis of the stained testicular interstitium were compared with sham-treated controls, as well as with castrated and intact rats during sexual development. At 4 weeks post-implantation, serum testosterone was detectable in Leydig cell recipients, but not in surgical controls, and progressively increased as a function of time until reaching levels comparable with sexually mature males at 12 weeks post-implantation. Histological analysis revealed a high rate of Leydig cell survival as well as steroidogenic secretory activity. Therefore, we conclude that mature Leydig cell transplantation in prepubertal hypogonadism recipients has therapeutic potential in rats and merits further investigation for clinical application.

Analysis on composition and inclusions of ballpoint pen tip steel

Ballpoint pen tip steel, a super free-cutting stainless steel, exhibits excellent corrosion resistance and good machining properties. In this study, inductively coupled plasma spectroscopy, metallographic microscopy, and scanning electron microscopy were used to determine the elemental contents in five ballpoint pen tips and their components, morphologies, and inclusion distributions. The results showed that the steels were all S–Pb–Te super free-cutting ferritic stainless steel. The free-cutting phases in the steels were mainly Mn S, Pb, and small amounts of Pb Te. Mn S inclusions were in the form of chain distributions, and the aspect ratio of each size inclusion in the chain was small. The stress concentration effect could substantially reduce the cutting force when the material was machined. Some of the Pb was distributed evenly in the steel matrix as fine particles（1–2 μm）, and the rest of the Pb was distributed at the middle or at both ends of the Mn S inclusions. The Pb plays a role in lubrication and melting embrittlement, which substantially increases the cutting performance. Pb Te was also usually distributed in the middle and at both ends of the Mn S inclusions, and Te could convert the sulfides into spindles, thereby improving the cutting performance of the steel.

Genomic and Phenotypic Diversity of Carbapenemase-Producing Enterobacteriaceae Isolates from Bacteremia in China: A Multicenter Epidemiological, Microbiological, and Genetic Study

Carbapenemase-producing Enterobacteriaceae(CPE) isolates are recognized as one of the most severe threats to public health. However, the population structure and genetic characteristics of CPE isolates among bloodstream infections(BSIs) are largely unknown. To address this knowledge gap, in this study,we included patients with clinically significant BSIs due to Enterobacterales isolates, recruited from 26 sentinel hospitals in China(2014–2015). CPE isolates were microbiologically and genomically characterized,including their susceptibility profiles, molecular typing, phylogenetic features, and genetic context analysis of carbapenemase-encoding genes. Of the 2569 BSI Enterobacterales isolates enrolled, 42(1.6%) were carbapenemase-positive. Moreover, among the 2242 investigated isolates, 1111(49.6%) extendedspectrum β-lactamase(ESBL)-producing isolates were identified in Escherichia coli(E. coli), Klebsiella pneumoniae(K. pneumoniae), Proteus mirabilis(P. mirabilis), and Klebsiella oxytoca. Whole genome sequencing analysis showed the clonal spread of K. pneumoniae carbapenemase(KPC)-2-producing K. pneumoniae sequence type(ST) 11 and New Delhi metallo-β-lactamase(NDM)-5-producing E. coli ST167 in our collection. Plasmid analysis revealed that carbapenemase-encoding genes were located on multiple plasmids. A high prevalence of biofilm-encoding type 3 fimbriae clusters and yesiniabactin-associated genes was observed in K. pneumoniae isolates. This work demonstrates the high prevalence of ESBLs and the wide dissemination of CPE among BSI isolates in China, which represent real clinical threats. Moreover, our findings first illustrate a more comprehensive genome scenario of CPE isolates among BSIs. The clonal spread of KPC-2-producing K. pneumoniae ST11 and NDM-5-producing E. coli ST167 needs to be closely monitored.

Main deposit styles and associated tectonics of the West Junggar region,NW China

The West Junggar region, located in the loci of the Central Asian Orogenic Belt, is a highly endowed metallogenic province with 〉100 tonnes Au, 〉0.7 Mt Cu, 〉0.3 Mt Mo, and 〉2.3 Mt chromite as well as significant amounts of Be and U. The West Junggar region has three metallogenic belts distributed systematically from north to south： （1） late Paleozoic Saur Au-Cu belt; （2） early Paleozoic Xiemisitai- Sharburt Be-U-Cu-Zn belt; （3） late Paleozoic Barluk-Kelamay Au-Cu-Mo-Cr belt. These belts host a number of deposits belonging to at least eight economically important styles, including epithermal Au, granite-related Be-U, volcanogenic massive sulfide （VMS） Cu-Zn, podiform chromite, porphyry Cu, hydrothermal quartz vein Au, porphyry-greisen Mo（-W）, and orogenic Au. These deposit styles are associated with the tectonics prevalent during their formation. Five tectonic-mineralized epochs can be recognized： （1） Ordovician subduction-related VMS Cu-Zn deposit; （2） Devonian ophiolite-related podiform chromite deposit; （3） early Carboniferous subductionrelated epithermal Au and porphyry Cu deposits; （4） late Carboniferous subduction-related granite-related Be-U, porphyry Cu, and hydrothermal quartz vein Au deposits; and （5） late Carboniferous to early Permian subduction-related por- phyry-greisen Mo（-W） and orogenic Au deposits.

Genome assembly and resequencing analyses provide new insights into the evolution, domestication and ornamental traits of crape myrtle

Crape myrtle(Lagerstroemia indica)is a globally used ornamental woody plant and is the representative species of Lagerstroemia.However,studies on the evolution and genomic breeding of L.indica have been hindered by the lack of a reference genome.Here we assembled the first high-quality genome of L.indica using PacBio combined with Hi-C scaffolding to anchor the 329.14-Mb genome assembly into 24 pseudochromosomes.We detected a previously undescribed independent whole-genome triplication event occurring 35.5 million years ago in L.indica following its divergence from Punica granatum.After resequencing 73 accessions of Lagerstroemia,the main parents of modern crape myrtle cultivars were found to be L.indica and L.fauriei.During the process of domestication,genetic diversity tended to decrease in many plants,but this was not observed in L.indica.We constructed a high-density genetic linkage map with an average map distance of 0.33 cM.Furthermore,we integrated the results of quantitative trait locus(QTL)using genetic mapping and bulk segregant analysis(BSA),revealing that the major-effect interval controlling internode length(IL)is located on chr1,which contains CDL15,CRG98,and GID1b1 associated with the phytohormone pathways.Analysis of gene expression of the red,purple,and white flower-colour flavonoid pathways revealed that differential expression of multiple genes determined the flower colour of L.indica,with white flowers having the lowest gene expression.In addition,BSA of purple-and green-leaved individuals of populations of L.indica was performed,and the leaf colour loci were mapped to chr12 and chr17.Within these intervals,we identified MYB35,NCED,and KAS1.Our genome assembly provided a foundation for investigating the evolution,population structure,and differentiation of Myrtaceae species and accelerating the molecular breeding of L.indica.

Photovoltaic molecules based on vinylene-bridged oligothiophene applied for bulk-heterojunction organic solar cells

We have synthesized two photovoltaic molecules（HEX-3TVT-ID and EH-3TVT-ID） based on vinylenebridged oligothiophene applied as donor for the solution-processable bulk-heterojunction organic solar cells（OSCs）. Vinylene unit was introduced as π-bridge in the oligothiophenes with 1,3-indenedione as end group and 4,4’-dihexyl-2,2’：5’,2’-terthiophene or 3’,4’-di（octan-3-yl）-2,2’：5’,2’-terthiophene as core,respectively. Due to the different substituent positions of the alkyl group relative to the vinylene unit in the terthiophene, HEX-3TVT-ID and EH-3TVT-ID show different optical and electrochemical properties, corresponding to the photovoltaic performance of the OSCs devices. The power conversion efficiency（PCE） of the OSCs based on a blend of HEX-3TVT-ID and PC71BM（1：0.8, weight ratio, 0.5% CN） reached 2.3%. In comparison, the OSCs based on the blend of EH-3TVT-ID and PC71BM in the weight ratio of 1：1 without the additive show a higher PCE of 2.7%, with a typically high VOC of 0.93 V, under the illumination of AM 1.5, 100 mW cm-2.

Effects of Two Drugs on Small Intestinal Epithelial Lymphocytes of Experimental Piglets with Spleen Deficiency

[ Objective] This study aimed to investigate the effects of Guchang Cuzhang powder and Smecta on small intestinal epithelial lymphocytes of piglets with spleen deficiency and diarrhea induced by Reserpine. [ Method] Eighteen piglets with reserpine-induced spleen deficiency and diarrhea were selected and randomly divided into three groups, six per group, including Guchang Cuzhang powder group, Smeeta group and spleen deficiency control group. Piglets in two drug adnfinistration groups were treated for 7 d using Guchang Cuzhang powder and Smecta, respectively. On the 2nd d and 8th d after drug withdrawal, three piglets in each group were euthanized by jugular vein bleeding to death. Intestine segments in different groups were collected for paraffin embedding, section preparation and HE staining, to conduct histological observation and count the number of small intestinal epithelial lymphocytes. [ Result ] Compared with the spleen deficiency control group, the number of lymphocytes in small intestinal epithelium of piglets in two drug administration groups increased significantly; in addition, the number of lymphocytes in small intestinal epithelium of piglets in Guchang Cuzhang powder group was significantly higher than that in Smecta group. [ Conclusion ] This study provided theoretical basis for the clinical applieation of Guchang Cuzhang powder and Smecta.

Risk factors for primary gout and hyperuricemia

Objective:Through epidemiological investigation,to investigate the etiology and influencing factors of primary gout and hyperuricemia(HUA).Methods:Using case-control methods,designed questionnaires on gout and/or HUA related factors(living habits,eating habits and environmental factors,etc).Logistic regression analysis of the survey results was performed with SPSS 19.0 software.Results:(1)Univariate Logistic regression analysis:11 risk factors with statistical significance(P<0.05),often eat sauce food,often eat Fried food,often eat asparagus,often eat nuts,often drink,smoking,drink water<1000ml per day,residential temperature≤17℃in winter,work environment average temperature≤17℃in winter,often exposure to toxic and harmful substances,often use induction cooker or microwave oven(P<0.05),the OR values were 2.063,1.701,3.242,1.560,2.055,1.338,5.700,5.330,2.305,2.821,1.701;3 protective factors,occasionally eat fresh fruit,wake up between 5 and 7 am,use the computer less than 1 hour per day(P<0.05),OR values were 0.723,0.611 and 0.558,respectively.(2)Multivariate Logistic regression analysis was performed for all factors:6 risk factors,The risk factors were often drink,drink water<1000ml per day,residential temperature≤17℃in winter,work environment average temperature≤17℃in winter,use mobile network cellphones and use unicom network cellphones(P<0.05),OR values are 2.008,4.240,4.034,1.889,2.207 and 1.891,respectively;2 protective factors:occasionally eat agaric and use the computer less than 1 hour per day(P<0.05),OR values were 0.551 and 0.536,respectively.Conclusions:Proper improvement of diet structure,adjustment of life and behavior,and avoidance of environmental risk factors can effectively reduce uric acid level,control the incidence of HUA and gout,and improve health level.

Screening of Chinese Herbal Medicines against Avian Infectious Laryngotracheitis Virus and Escherichia coli

[ Objective] This study aimed to screen Chinese herbal medicines against avian infectious laryngotracheitis virus and Escherichia coli. [ Method ] Conventional Chinese medicine plate dilution method, plate punching method and test tube method were applied to screen Chinese herbal medicines against avian infectious laryngotracheitis virus based on chicken embryo inoculation experiment. [ Result ] Forsythia suspensa, Radix lsatidis, Isatis iadigotica, Lonicera japonica, Codonopsis pilosula, Astragalus membranaceus, Rhizoma Atractylodis Macrocephalae, C, tyeyrrhiza uralensis and Pericarpium granati had relatively strong anti-ILTV effect; among the Chinese herbal medicines against avian E. coli, Sanguisorba offwinalis, Fructus Mume, Rheum palmatum, Anemarrhena asphodeloides, Radix Scutellariae and Fagopyrum cymosum had relatively strong effect against avian E. coli Os, while other Chinese herbal medicines had relatively weak or no inhibitory effect on avian E. coli 0s and 05. [ Conclusion] This study laid the foundation for further development of Chinese herbal medicine compound preparations to treat avian infectious laryngotracheitis, avian colibacillosis and other viral diseases and bacterial diseases.

Histopathological Observation of Goose Escherichia coli Disease

[ Objective] This study aimed to provide reliable basis for in-depth understanding of histopathological changes in geese suffering from Escherichia coli disease and accurate diagnosis of goose E. coli disease. [ Method] By using paraffin embedding, section slicing and HE staining, histopathological changes in the heart, liver, spleen, lung, kidney and small intestine tissues of three diseased geese were observed. [ Result] The liver generated protein fiber membranes, showing liver cell degeneration, increasing number of red blood cells in sinusoids and liver congestion; the kidney had relatively serious lesions, including renal tubular epithelial cell degeneration, necrosis and shedding from the basement membrane and hyaline degeneration of glomerulars. The lung showed epithelial cell degeneration and necrosis and was filled with a large number of red blood cells and shedded epithelial cells, showing typical red hepatization; a large number of red blood ceils were aggregated in pulmonary blood vessels, resulting in lung congestion. Epithelial ceils of various digestive tubes all showed varying degrees of minor shed- ding and local infiltration of inflammatory ceils, thereby leading to death of geese due to substance metabolism, electrolyte and acid-base balance disorders and metabolic acidosis. [ Conclusion] Based on epidemiology survey, clinical symptom observation, pathological necropsy and laboratory diagnosis, the diseased geese were confirmed to be suffering from E. coli disease.

Histopathological Observation of Classical Swine Fever in Newborn Piglets

[ Objective] This study aimed to investigate pathological changes in various organs of piglets infected with classical swine fever and provide reliable basis for accurate diagnosis of classical swine fever. [ Method] By using paraffin embedding, section slicing and HE staining, histopathological changes in the heart, liver, spleen, lung, kidney and small intestine tissues of five diseased piglets were observed. C Result] Classical swine fever virus could lead to multiple visceral and mueosal hemorrhages, inflammatory cell infiltration, necrosis and other pathological changes. [ Conclusion ] Classical swine fever virus can further cause progressive degeneration and necrosis of different cells, resulting in immune injury.

Design and Application of Integrated Monitoring Model for Provincial Meteorological Observation Data Transmission

With the development of meteorological services, there are more and more types of real-time observation data, and the timeliness requirements are getting higher and higher. The monitoring methods of existing meteorological observation data transmission can no longer meet the needs. This paper proposes a new monitoring model, namely the “integrated monitoring model” for provincial meteorological observation data transmission. The model can complete the whole network monitoring of meteorological observation data transmission process. Based on this model, the integrated monitoring system for meteorological observation data transmission in Guangdong Province is developed. The system uses Java as the programming language, and integrates J2EE, Hibernate, Quartz, Snmp4j and Slf4j frameworks, and uses Oracle database as the data storage carrier, following the MVC specification and agile development concept. The system development uses four key technologies, including simple network management protocol, network connectivity detection technology, remote host management technology and thread pool technology. The integrated monitoring system has been put into business application. As a highlight of Guangdong’s meteorological modernization, it has played an active role in many major meteorological services.

A Histological Study on Subacute Toxicity of "Baikening" in Hy-Line Brown Roosters

[ Objective] A histological study was conducted to investigate the toxicity of ＂Baikening＂ and the toxic effect of ＂Baikening＂ on roosters after longer- term administration at different dose levels. [ Method] Thirty 21-day-old Hy-Line Brown roosters were administered with 0.5 and 1.0 ml of ＂Balkening＂ aqueous extract through drinking water once a day for continuous 14 d. Roosters in control group and experimental groups after drug administration for 14 d and drug with- dmwal for 7 d were euthatfized; livers, kidneys, thymuses, spleens and bursas of Fabricius were collected and weighed for comparative analysis. Various tissues were prepared into paraffin-embedded slices and stained by H. E. , to observe histological changes of various organs under an optical microscope. [ Result ] After drug administration for 14 d, all the roosters in experimental groups survived; there was no visible pathological change in various organs of Hy-Line Brown roosters in each group; organ weights of Fly-Line Brown roosters in various groups showed no significant difference; observation results of tissue slices indicated that there was no pathological change in fine structures, nuclei and cytoplasm of various organs of Hy-Line Brown roosters in different groups ; various blood vessels in different organs also presented no change in blood circulation or other pathological changes. [ Conclusion] ＂Baikening＂ aqueous extract （oral administration） has no toxic and side effect on roosters in the subacute toxicity experiment.

Clinical study on Chuanxiong Hualiu Mixture in the treatment of blood stasis and phlegm stagnation type of ovarian cyst

Objective:To observe the clinical efficacy of Chuanxiong Hualiu Mixture in the treatment of blood stasis and phlegm stagnation type of ovarian cyst and the effects on physical and chemical indicators.Methods: A total of 80 patients with blood stasis and phlegm stagnation type of ovarian cyst were randomly divided into two groups, research group (n=40) took Chuanxiong Hualiu Mixture, control group (n=40) took Guizhi Fuling Capsule, 3 months was a course of treatment, and the curative effect was compared between two groups.Results:(1) The overall response rate of Chuanxiong Hualiu mixture group after 3 months of treatment was 82.5%, that of Guizhi Fuling Capsule group was 62.5%, the overall response rate of Chuanxiong Hualiu mixture group was higher than that of control group, and the difference was statistically significant;(2) before and after treatment, sex hormone and hemorheology index E2 of both groups decreased significantly, whole blood viscosity, whole blood reduced viscosity and plasma viscosity decreased significantly, the results were statistically significant, but there was no difference between two groups;(3) rank sum test of TCM symptom efficacy between two groups before and after treatment showed that the overall response rate of Chuanxiong Hualiu mixture group was 95%, the overall response rate of Guizhi Fuling Capsule group was 85%, the overall response rate of research group was better than that of control group, and the difference was statistically significant.Conclusion:Chuanxiong Hualiu mixture has good curative effect for the treatment of ovarian cyst, it can effectively improve the patients' blood stasis and phlegm stagnation constitution, and its mechanism of action is associated with lowering estrogen levels and improving hemorrheology.

Evaluating the integrated antimicrobial stewardship system of China by the assessment tool of WHO

Objective:To fully understand the overall system and implementation of antimicrobial stewardship(AMS)at different levels in China,an evaluation according to the integrated AMS evaluation tool developed by World Health Organization(WHO)was conducted.Methods:A comprehensive search on the AMS relevant government policies,regulations,scientific research results,public and social activities was conducted,and the implementation of AMS strategies in national,subnational and hospital level were evaluated by the standards of the WHO.Results:The results shew that the system construction,technical infrastructure and actions of AMS in China at the national level is relatively satisfied,but the AMS system needs to be further strengthened at the subnational and the medical institutional level,especially the integration of multidisciplinary teams and relevant departments;the implementation of professional intervention strategies,national education and publicity,professional education and training are relatively weak.AMS implementation is mainly promoted at the national level,and AMS in primary medical institutions is almost missing.It is necessary to carry out AMS at the provincial level and medical institutions as soon as possible.The focus is to establish a professional AMS team,prepare AMS guideline,implement AMS strategy,raise public awareness and ensure the long‐term and sustainable development of AMS in the country.Conclusion:The Chinese government has established a system for AMS,and implemented a multisectoral coordinative mechanism.However,at the subnational and district levels,an AMS system and practice should be set up soon to promote the rational use of antibiotics.

Effect of Mg-treatment on transformation of oxide inclusions in X80 pipeline steel

In order to investigate the modification behavior and regularity of inclusions in X80 pipeline steel by Mg-treatment, the comparative industrial experiments of Mg-treatment and Ca-treatment in X80 pipeline steel were carried out. Mg and Ca were added to the steel in the form of cored wire after RH (Ruhrstahl-Hereaeus vacuum degassing) process. After adding Ca-containing cored wire, the inclusions were transformed into CaO–Al_(2)O_(3) in the steel. With the progress of smelting, the cleanliness of molten steel became worse, and the equivalent diameter of inclusions was at a higher level. Mg-treatment had a good effect on the modification of inclusions. After Mg-containing cored wire was added to the steel, Al_(2)O_(3) and CaO–Al_(2)O_(3) in the steel were transformed into MgO, MgO·Al_(2)O_(3), and CaO–MgO–Al_(2)O_(3) inclusions, which were basically spherical. The initial precipitated MgO became the core of other inclusions in the steel, which promotes the precipitation of MgO·Al_(2)O_(3). After Mg-treatment, almost no unmodified calcium aluminate inclusions existed in the hot rolled plate, and the cleanliness of the steel was improved. The effect of Ca and Mg on the transformation of inclusions in pipeline steel was studied by thermodynamic calculation, the result of which is consistent with the experimental results.

Reaction mechanism between Al_(2)O_(3)–MgO refractory materials and rare earth high-carbon heavy rail steel

Submerged entry nozzle(SEN)clogging is a major problem affecting the production quality of rare earth steel,and finding a suitable refractory outlet can significantly reduce production costs.To explore the relationship between refractory composition and interface interaction,unprotected coated Al_(2)O_(3)–MgO refractories and SiO2-coated Al_(2)O_(3)–MgO refractories were added to rare earth high-carbon heavy rail steel under laboratory conditions,and the Al_(2)O_(3)–MgO refractory was found to be more suitable.The results show that,from the epoxy resin side to the refractory side,the contour of the refractory interface reaction layer can be divided into two main layers:an iron-rich reaction layer and an iron-poor reaction layer.Calculations based on the spherical model suggest that the adhesion force is proportional to the size of the refractory particles and inclusions,and the same result applies to the surface tension.Controlling the inclusions at a smaller size has a specific effect on alleviating the erosion of refractories.Combined with the erosion mechanism of Al_(2)O_(3)–MgO refractories,the interface reaction mechanism between Al_(2)O_(3)–MgO refractories and molten steel was proposed,which provides ideas for solving SEN clogging.