Since the current slagging of argon blowing refining process is relatively fixed,which cannot adapt to the fluctuation of converter smelting process,it poses the problems of poor metallurgical property of refining sla...Since the current slagging of argon blowing refining process is relatively fixed,which cannot adapt to the fluctuation of converter smelting process,it poses the problems of poor metallurgical property of refining slag and a large amount of molten heel.An optimization system coupled with multiple models was proposed to dynamic control the ladle slagging in the argon blowing refining process.It can compile the optimal dynamic slagging scheme in real time under the guarantee of deoxidation performance and reasonable fluidity.The argon blowing refining slag composition range of CaO/Al_(2)O_(3)=1.3-1.7,CaO/SiO_(2)=6-12,w(MgO)=2%-6% was determined based on FeO activity and liquidus temperature by equilibrium thermodynamic calculation.In addition,it demonstrated better performance in the viscosity prediction task of the presented Visual Geometry Group 16-like one-dimensional convolutional neural network deep learning algorithm versus the Random Forest ensemble learning algorithm,as the adjusted coefficients of determination were 0.9712 and 0.9637,respectively.After the system was applied in operation,the argon blowing refining process was stable,and the steel yield was enhanced,which promoted the intelligent steelmaking level while achieving the cost reduction and efficiency improvement.展开更多
BACKGROUND Colon polyps represent a significant clinical challenge in elderly patients.While endoscopic mucosal resection(EMR)and argon plasma coagulation(APC)are widely used,their comparative effectiveness in elderly...BACKGROUND Colon polyps represent a significant clinical challenge in elderly patients.While endoscopic mucosal resection(EMR)and argon plasma coagulation(APC)are widely used,their comparative effectiveness in elderly populations remains unclear,particularly regarding postoperative recovery and complication profiles.AIM To compare the postoperative recovery,complications and efficacy of EMR and APC in elderly patients with colonic polyps.METHODS We retrospectively analyzed clinical data from 224 elderly patients with colon polyps treated at our center between January 2021 and July 2024.All patients were divided into the EMR group and APC group according to the surgical method they received.By comparing the operation time,intraoperative bleeding situation,hospital stays,postoperative inflammatory response index,complication rate and recurrence status of the two groups,the effect of the two surgical methods was comprehensively evaluated.RESULTS The APC group exhibited superior outcomes in terms of operative time(10.63 minutes vs 13.27 minutes,P<0.001),intraoperative bleeding situation(39.00%vs 52.42%,P=0.031),and length of hospital stay(1.63 days vs 3.87 days,P<0.001)compared to the EMR group.The one-time resection rate of the APC group(94.69%)was higher than that of the EMR group(89.14%)(P=0.026).The overall effective rates of the two groups were 94.35%and 92.00%,respectively.Postoperative procalcitonin and C-reactive protein levels were lower in the APC group than in the EMR group(P<0.001).The incidence of complications was comparable between the two groups(P=0.159).The recurrence rate was lower in the APC group(2.00%)than in the EMR group(8.06%)(P=0.045).CONCLUSION For elderly patients with colon polyps,APC showed certain advantages compared with EMR in promoting postoperative recovery,reducing the inflammatory response and the risk of complications.However,the study is limited by its single-center retrospective design and short follow-up period,and further multicenter prospective studies are needed to validate the findings.展开更多
Based on atomic crystal configurations,we studied many-body interaction properties of face-centered cubic(fcc)solid argon(Ar)within the atomic distance range of 2.0A to 3.6A at T=300 K.The resulting EOS can accurately...Based on atomic crystal configurations,we studied many-body interaction properties of face-centered cubic(fcc)solid argon(Ar)within the atomic distance range of 2.0A to 3.6A at T=300 K.The resulting EOS can accurately describe the compression behavior of solid Ar under the experimentally investigated pressure range(0~114GPa).Statistically,903(Ar)2 clusters were identified,corresponding to 12 distinct geometric configurations,861(Ar)3 clusters correspond to 25 distinct geometric configurations,816(Ar)4clusters correspond to 27 distinct geometric configurations,and the calculation results exhibited good convergence.For comparative purposes,the EOS of fcc solid Ar was also calculated using a two-body potential-only approach,which showed excellent agreement with experimental data under relevant pressures.Incorporating three-body terms extended the EOS accuracy to 80 GPa,while the inclusion of four-body terms further improved the precision up to 114 GPa.Higher-order many-body terms are expected to enable accurate interpretation of experimental phenomena in solid Ar above 114 GPa.In addition,when the molar volume is reduced to a fixed value,the zero-point vibration pressure has already reached a certain proportion,then it must be considered and cannot be ignored.This study provides a reliable theoretical model for the study of high-pressure properties and zero-point energy of rare gas solids.展开更多
Jargon in English language, part of culture, is a sub-culture. This paper illustrates its connotation, original facts, constructions, functions and characteristics. This study helps us fully recognize British and Amer...Jargon in English language, part of culture, is a sub-culture. This paper illustrates its connotation, original facts, constructions, functions and characteristics. This study helps us fully recognize British and American societies from another angle, and understand diversity of their cultures to benefit English teaching and intercultural communication.展开更多
The thermodynamic phase stability area diagrams of BCl3-NH3-Si Cl4-H2-Ar system were plotted via Factsage software to predict the kinetic experimental results. The effects of parameters(i e, partial pressure of reacta...The thermodynamic phase stability area diagrams of BCl3-NH3-Si Cl4-H2-Ar system were plotted via Factsage software to predict the kinetic experimental results. The effects of parameters(i e, partial pressure of reactants, deposition temperature and total pressure) on the distribution regions of solid phase products were analyzed based on the diagrams. The results show that:(a) Solid phase products are mainly affected by deposition temperature. The area of BN+Si3N4 phase increases with the temperature rising from 650 to 900 ℃, and decreases with the temperature rising from 900 to 1 200 ℃;(b) When temperature and total pressure are constants, BN+Si3N4 phase exists at a high partial pressure of NH3;(c) The effect of total system pressure is correlated to deposition temperature. The temperature ranging from 700 to 900 ℃ under low total pressure is the optimum condition for the deposition.(d) Appropriate kinetic parameters can be determined based on the results of thermodynamic calculation. Si–B–N coating is obtained via low pressure chemical vapor deposition. The analysis by X-ray photoelectron spectroscopy indicates that B–N and Si–N are the main chemical bonds of the coating.展开更多
BACKGROUND Chronic radiation proctitis(CRP) is a complication which occurs in 1%-5% of patients who undergo radiotherapy for pelvic malignancies. Although a wide range of therapeutic modalities are available, there is...BACKGROUND Chronic radiation proctitis(CRP) is a complication which occurs in 1%-5% of patients who undergo radiotherapy for pelvic malignancies. Although a wide range of therapeutic modalities are available, there is no literature to date showing any particularly appropriate therapeutic modality for each disease stage. Argon plasma coagulation(APC) is currently recommended as the firstchoice treatment for hemorrhagic CRP, however, its indication based on longterm follow-up is still unclear. On the hypothesis that the long-term efficacy and safety of APC are not fully understood, we reviewed APC treatment for patients with hemorrhagic CRP from a single center.AIM To assess the long-term efficacy and safety of APC for hemorrhagic CRP.METHODS This is a retrospective study of consecutive patients treated with APC for hemorrhagic CRP from January 2013 to October 2017. Demographics, clinical variables, and typical endoscopic features were recorded independently. Success was defined as either cessation of bleeding or only occasional traces of bloody stools with no further treatments for at least 12 mo after the last APC treatment.We performed univariate and multivariate analyses to identify factors associated with success and risk factors for fistulas.RESULTS Forty-five patients with a median follow-up period of 24 mo(range: 12-67 mo)were enrolled. Fifteen(33.3%) patients required blood transfusion before APC.Successful treatment with APC was achieved in 31(68.9%) patients. The mean number of APC sessions was 1.3(1-3). Multivariate analysis showed that APC failure was independently associated with telangiectasias present on more than50% of the surface area [odds ratio(OR) = 6.53, 95% confidence interval(CI): 1.09-39.19, P = 0.04] and ulcerated area greater than 1 cm^2(OR = 8.15, 95%CI: 1.63-40.88, P = 0.01). Six(13.3%) patients had severe complications involving rectal fistulation. The only factor significantly associated with severe complications was ulcerated area greater than 1 cm^2(P = 0.035).CONCLUSION The long-term efficacy of APC for hemorrhagic CRP is uncertain in patients with telangiectasias present on > 50% of the surface area and ulceration > 1 cm^2.展开更多
AIM: To report the long-term outcome of patients after complete ablation of non-neoplastic Barrett's esophagus (BE) with respect to BE relapse and development of intraepithelial neoplasia or esophageal adenocarcin...AIM: To report the long-term outcome of patients after complete ablation of non-neoplastic Barrett's esophagus (BE) with respect to BE relapse and development of intraepithelial neoplasia or esophageal adenocarcinoma. METHODS: In 70 patients with historically proven non neoplastic BE, complete BE ablation was achieved by argon plasma coagulation (APC) and high-dose proton pump inhibitor therapy (120 mg omeprazole daily). Sixty-six patients (94.4%) underwent further surveillance endoscopy. At each surveillance endoscopy four-quadrant biopsies were taken from the neo-squamous epithelium at 2 cm intervals depending on the pre-treatment length of BE mucosa beginning at the neo-Z-line, and from any endoscopically suspicious lesion. RESULTS: The median follow-up of 66 patients was 51 mo (range 9-85 mo) giving a total of 280.5 patient years. A mean of 6 biopsies were taken during surveillance endoscopies. In 13 patients (19.7%) tongues or islands suspicious for BE were found during endoscopy. In 8 of these patients (12.1%) non-neoplastic BE relapse was confirmed histologically giving a histological relapse rate of 3% per year. In none of the patients, intraepithelial neoplasia nor an esophageal adenocarcinoma was detected. Logistic regression analysis identified endoscopic detection of islands or tongues as the only positive predictor of BE relapse (P= 0.0004). CONCLUSION: The long-term relapse rate of non neoplastic BE following complete ablation with high-power APC is low (3% per year).展开更多
The Jinding superlarge lead and zinc deposit has attracted the attention of geologists of the world and its metallogenesis has long been in dispute. This paper takes the Jinding deposit and the Baiyangping Cu-Ag-Co de...The Jinding superlarge lead and zinc deposit has attracted the attention of geologists of the world and its metallogenesis has long been in dispute. This paper takes the Jinding deposit and the Baiyangping Cu-Ag-Co deposit which was recently found at about 30 km north of Jinding as one ore belt, and, based on researches on the helium, argon, and xenon isotopic compositions of primary inclusions in ore-forming solutions of the main stage, the authors have found that the 3He/4He ratio of the ore-forming fluid is 2.7×10?6 (varying from 0.19 to 1.97 Ra), the 4He/40Ar ratio (0.24–3.12) is close to the mantle characteristic ratio, and the xenon isotopic composition and evolution show characters of the mantle xenon. The above results reveal the characteristics of mantle source and crust-mantle fluid mixing (mantle helium reaching 32%) and the metallogenic contributions of the deep processes in the Jinding-Baiyangping ore belt.展开更多
AIM: This prospective study evaluated the effectiveness of 90 W argon plasma coagulation (APC) for the ablation of Barrett's esophagus (BE) that is considered to be the main risk factor for the development of esop...AIM: This prospective study evaluated the effectiveness of 90 W argon plasma coagulation (APC) for the ablation of Barrett's esophagus (BE) that is considered to be the main risk factor for the development of esophageal adenocarcinoma.METHODS: The results from 25 patients, observed at the First Department of General Surgery, University of Verona, Italy, from October 2000 to October 2003, who underwent APC for histologically proven BE were prospectively analyzed.RESULTS: The ablation treatment was completed in all the patients but one (96%). The mean number of APC sessions needed to complete ablation was 1.6 (total number: 40). The eradication was obtained in the majority of cases by one session only (60%), two sessions were required in 24% of the cases and three or more in 16%.About 43% of the sessions were complicated. Retrosternal pain (22.5%) and fever (17.5%) were the most frequent symptoms. Only one major complication occurred, it was an hemorrhage due to ulcer formation on the treated esophagus that required urgent endoscopic sclerosis and admission. The follow-up was accomplished in all the patients with a mean period of 26.3 mo and 20 patients (84%) with a follow-up period longer than 24 mo. Only one patient showed a relapse of metaplastic mucosa 12 mo after the completion of ablation. The patient was hence re-treated and now is free from recurrence 33 mo later.CONCLUSION: High power setting (90 W) APC showed to be safe and effective. The effects persist at a mean follow-up period of two years with a comparable cost in term of complications with respect to standard power settings. Further studies with greater number of patients are required to confirm these results and to assess if ablation reduces the incidence of malignant progression.展开更多
Based on the isotopic chronologic results of Cenozoic alkali basalts from the South China Sea, the characteristics of volcanic activi- ty of the South China Sea after spreading were studied. The potassium - argon ages...Based on the isotopic chronologic results of Cenozoic alkali basalts from the South China Sea, the characteristics of volcanic activi- ty of the South China Sea after spreading were studied. The potassium - argon ages of eight alkali basalt samples from the South China Sea, and the argon - argon ages of two samples among them are reported. Apparent ages of the whole rock are 3.80 to 7. 91 Ma with an average value of 5.43 Ma （potassium- argon, whole rock）, and there is little difference among samples at the same location, e. g. , 4. 76 - 5.78 Ma for location S（M-12. The argon - argon ages for the two samples are 6.06 and 4. 71 Ma, which lie within the age scope of potassium - argon method. The dating results indicate that rock-forming age is from late Miocene to Pliocene, which is consistent with erupting event for alkali basalts from adjacent regions of the South China Sea. Volcanic activities occur after the cessation of spreading of the South China Sea, which are controlled by lithospheric fault and the spreading center formed during the spreading period of the South China Sea. These dating results, combined with geochemical characteristics of these basalts, the published chronological data for the South China Sea and its adjacent regions, and the updated geophysical data near Hainan Island, suggest that after the cessation of spreading of the South China Sea, there occur widely distributing magmatic activities which primarily is alkali basalt, and the volcanic activity continues to Quaternary. The activity may be relative to Hainan mantle plume originated from core/mantle boundary.展开更多
We previously found that argon exerts its neuroprotective effect in part by inhibition of the toll-like receptors(TLR)2 and 4.The downstream transcription factors signal transducer and activator of transcription 3(STA...We previously found that argon exerts its neuroprotective effect in part by inhibition of the toll-like receptors(TLR)2 and 4.The downstream transcription factors signal transducer and activator of transcription 3(STAT3)and nuclear factor kappa B(NF-κB)are also affected by argon and may play a role in neuroprotection.It also has been demonstrated that argon treatment could mitigate brain damage,reduce excessive microglial activation,and subsequently attenuate brain inflammation.Despite intensive research,the further exact mechanism remains unclear.In this study,human neuroblastoma cells were damaged in vitro with rotenone over a period of 4 hours(to mimic cerebral ischemia and reperfusion damage),followed by a 2-hour post-conditioning with argon(75%).In a separate in vivo experiment,retinal ischemia/reperfusion injury was induced in rats by increasing intraocular pressure for 1 hour.Upon reperfusion,argon was administered by inhalation for 2 hours.Argon reduced the binding of the transcription factors signal transducer and activator of transcription 3,nuclear factor kappa B,activator protein 1,and nuclear factor erythroid 2-related factor 2,which are involved in regulation of neuronal damage.Flow cytometry analysis showed that argon downregulated the Fas ligand.Some transcription factors were regulated by toll-like receptors;therefore,their effects could be eliminated,at least in part,by the TLR2 and TLR4 inhibitor oxidized phospholipid 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine(OxPAPC).Argon treatment reduced microglial activation after retinal ischemia/reperfusion injury.Subsequent quantitative polymerase chain reaction analysis revealed a reduction in the pro-inflammatory cytokines interleukin(IL-1α),IL-1β,IL-6,tumor necrosis factorα,and inducible nitric oxide synthase.Our results suggest that argon reduced the extent of inflammation in retinal neurons after ischemia/reperfusion injury by suppression of transcription factors crucial for microglial activation.Argon has no known side effects or narcotic properties;therefore,therapeutic use of this noble gas appears ideal for treatment of patients with neuronal damage in retinal ischemia/reperfusion injury.The animal experiments were approved by the Commission for Animal Care of the University of Freiburg(approval No.35-9185.81/G14-122)on October 19,2012.展开更多
The flow field of molten steel and the interfacial behaviour between molten steel and liquid slag layer in medium-thin slab continuous casting mold with argon gas injection were studied by numerical simulation, in whi...The flow field of molten steel and the interfacial behaviour between molten steel and liquid slag layer in medium-thin slab continuous casting mold with argon gas injection were studied by numerical simulation, in which the effects of nozzle submergence depth and port angle, casting speed, and argon gas flow rate on the flow and the level fluctuation of molten steel were considered. The results show that the molten steel is jetted from the submerged en- try nozzle （SEN） with three ports into the mold and forms three recirculation zones including one upper recireulation zone and two lower recirculation zones. Argon gas injection results in a secondary vortex flow in the upper zone near the nozzle. For a given casting speed and argon gas flow rate, increasing the side port angle and submergence depth of nozzle can effectively restrain the steel/slag interracial fluctuation. Increasing the casting speed would prick up the level fluctuation. For a fixed casting speed, argon gas flow rate has a critical value, the interracial fluctuation with argon gas injection are stronger than the case without argon gas injection when the argon gas flow rate is less than the critical value, but when the argon gas flow rate exceeds the critical value, the level fluctuation is calmer than that without argon gas injection.展开更多
In continuous casting,the argon blowing at the tundish upper nozzle is usually used to prevent nozzle clogging,whose effect is closely related to the migration of argon bubbles and the flow behavior of the liquid stee...In continuous casting,the argon blowing at the tundish upper nozzle is usually used to prevent nozzle clogging,whose effect is closely related to the migration of argon bubbles and the flow behavior of the liquid steel in the nozzle.Here,to investigate the effects of argon blowing at the tundish upper nozzle on multiphase flow behavior in nozzle,a threedimensional model of the tundish–nozzle–mold was established for numerical simulation.The results indicate that the argon bubbles injected from the inner wall of the tundish upper nozzle first move downward along the nozzle wall under the action of the liquid steel.As the distance from the tundish upper nozzle increases,the argon bubbles gradually diffuse to the center of the nozzle.Compared with no argon blowing,the liquid steel velocity increases in the center of the nozzle and decreases near the wall with argon blowing.With increasing the argon flow rate,the concentration of bubbles in the nozzle increases,and the process of bubble group diffusion to the center region of the nozzle speeds up.This in turn increases the liquid steel velocity at the center of the nozzle but reduces near the wall.With increasing the casting speed,the concentration of bubbles in the nozzle decreases,the length of the bubble group near the nozzle wall is extended,and the liquid steel velocity at the center region and near-wall region of the nozzle increases.The mechanism of argon blowing at the tundish upper nozzle to prevent nozzle clogging is mainly realized by the isolation effect of the argon bubble group on the inner wall of the nozzle.展开更多
The fluid flow and the interfacial phenomenon of slag and metal in tundish with gas blowing were studied with mathematical and physical modeling, and the effects of gas flowrate, the placement of porous beam for the g...The fluid flow and the interfacial phenomenon of slag and metal in tundish with gas blowing were studied with mathematical and physical modeling, and the effects of gas flowrate, the placement of porous beam for the generation of bubbles, and the combination of flow control devices on the flow and slag-metal interface were investigated. The results show that the position of gas bubbling has a significant effect on the flow in tundish, and the placement of porous beam and gas flowrate are the two main factors affecting the entrapment of slag in tundish. The closer the porous beam to the weir, the more reasonable is the flow, which is in favor of the control of slag entrapment in tundish.展开更多
基金the fund support from the Natural Science Foundation of Anhui Provincial Education Department(KJ2021A0358)the National Natural Science Foundation of China(51804004).
文摘Since the current slagging of argon blowing refining process is relatively fixed,which cannot adapt to the fluctuation of converter smelting process,it poses the problems of poor metallurgical property of refining slag and a large amount of molten heel.An optimization system coupled with multiple models was proposed to dynamic control the ladle slagging in the argon blowing refining process.It can compile the optimal dynamic slagging scheme in real time under the guarantee of deoxidation performance and reasonable fluidity.The argon blowing refining slag composition range of CaO/Al_(2)O_(3)=1.3-1.7,CaO/SiO_(2)=6-12,w(MgO)=2%-6% was determined based on FeO activity and liquidus temperature by equilibrium thermodynamic calculation.In addition,it demonstrated better performance in the viscosity prediction task of the presented Visual Geometry Group 16-like one-dimensional convolutional neural network deep learning algorithm versus the Random Forest ensemble learning algorithm,as the adjusted coefficients of determination were 0.9712 and 0.9637,respectively.After the system was applied in operation,the argon blowing refining process was stable,and the steel yield was enhanced,which promoted the intelligent steelmaking level while achieving the cost reduction and efficiency improvement.
文摘BACKGROUND Colon polyps represent a significant clinical challenge in elderly patients.While endoscopic mucosal resection(EMR)and argon plasma coagulation(APC)are widely used,their comparative effectiveness in elderly populations remains unclear,particularly regarding postoperative recovery and complication profiles.AIM To compare the postoperative recovery,complications and efficacy of EMR and APC in elderly patients with colonic polyps.METHODS We retrospectively analyzed clinical data from 224 elderly patients with colon polyps treated at our center between January 2021 and July 2024.All patients were divided into the EMR group and APC group according to the surgical method they received.By comparing the operation time,intraoperative bleeding situation,hospital stays,postoperative inflammatory response index,complication rate and recurrence status of the two groups,the effect of the two surgical methods was comprehensively evaluated.RESULTS The APC group exhibited superior outcomes in terms of operative time(10.63 minutes vs 13.27 minutes,P<0.001),intraoperative bleeding situation(39.00%vs 52.42%,P=0.031),and length of hospital stay(1.63 days vs 3.87 days,P<0.001)compared to the EMR group.The one-time resection rate of the APC group(94.69%)was higher than that of the EMR group(89.14%)(P=0.026).The overall effective rates of the two groups were 94.35%and 92.00%,respectively.Postoperative procalcitonin and C-reactive protein levels were lower in the APC group than in the EMR group(P<0.001).The incidence of complications was comparable between the two groups(P=0.159).The recurrence rate was lower in the APC group(2.00%)than in the EMR group(8.06%)(P=0.045).CONCLUSION For elderly patients with colon polyps,APC showed certain advantages compared with EMR in promoting postoperative recovery,reducing the inflammatory response and the risk of complications.However,the study is limited by its single-center retrospective design and short follow-up period,and further multicenter prospective studies are needed to validate the findings.
基金sponsored by the Youth Talent(team)project of Gansu Province(Grant No.2025QNTD12)the Natural ScienceFoundation of Gansu Province(Grant No.25JRRM001,23JRRM0755).
文摘Based on atomic crystal configurations,we studied many-body interaction properties of face-centered cubic(fcc)solid argon(Ar)within the atomic distance range of 2.0A to 3.6A at T=300 K.The resulting EOS can accurately describe the compression behavior of solid Ar under the experimentally investigated pressure range(0~114GPa).Statistically,903(Ar)2 clusters were identified,corresponding to 12 distinct geometric configurations,861(Ar)3 clusters correspond to 25 distinct geometric configurations,816(Ar)4clusters correspond to 27 distinct geometric configurations,and the calculation results exhibited good convergence.For comparative purposes,the EOS of fcc solid Ar was also calculated using a two-body potential-only approach,which showed excellent agreement with experimental data under relevant pressures.Incorporating three-body terms extended the EOS accuracy to 80 GPa,while the inclusion of four-body terms further improved the precision up to 114 GPa.Higher-order many-body terms are expected to enable accurate interpretation of experimental phenomena in solid Ar above 114 GPa.In addition,when the molar volume is reduced to a fixed value,the zero-point vibration pressure has already reached a certain proportion,then it must be considered and cannot be ignored.This study provides a reliable theoretical model for the study of high-pressure properties and zero-point energy of rare gas solids.
文摘Jargon in English language, part of culture, is a sub-culture. This paper illustrates its connotation, original facts, constructions, functions and characteristics. This study helps us fully recognize British and American societies from another angle, and understand diversity of their cultures to benefit English teaching and intercultural communication.
基金Funded by the National Natural Science Foundation of China(Nos.51002120,51472201)
文摘The thermodynamic phase stability area diagrams of BCl3-NH3-Si Cl4-H2-Ar system were plotted via Factsage software to predict the kinetic experimental results. The effects of parameters(i e, partial pressure of reactants, deposition temperature and total pressure) on the distribution regions of solid phase products were analyzed based on the diagrams. The results show that:(a) Solid phase products are mainly affected by deposition temperature. The area of BN+Si3N4 phase increases with the temperature rising from 650 to 900 ℃, and decreases with the temperature rising from 900 to 1 200 ℃;(b) When temperature and total pressure are constants, BN+Si3N4 phase exists at a high partial pressure of NH3;(c) The effect of total system pressure is correlated to deposition temperature. The temperature ranging from 700 to 900 ℃ under low total pressure is the optimum condition for the deposition.(d) Appropriate kinetic parameters can be determined based on the results of thermodynamic calculation. Si–B–N coating is obtained via low pressure chemical vapor deposition. The analysis by X-ray photoelectron spectroscopy indicates that B–N and Si–N are the main chemical bonds of the coating.
基金Supported by National Natural Science Foundation of China,No.81573078the National Natural Science Foundation of Guangdong Province,No.2016A030311021
文摘BACKGROUND Chronic radiation proctitis(CRP) is a complication which occurs in 1%-5% of patients who undergo radiotherapy for pelvic malignancies. Although a wide range of therapeutic modalities are available, there is no literature to date showing any particularly appropriate therapeutic modality for each disease stage. Argon plasma coagulation(APC) is currently recommended as the firstchoice treatment for hemorrhagic CRP, however, its indication based on longterm follow-up is still unclear. On the hypothesis that the long-term efficacy and safety of APC are not fully understood, we reviewed APC treatment for patients with hemorrhagic CRP from a single center.AIM To assess the long-term efficacy and safety of APC for hemorrhagic CRP.METHODS This is a retrospective study of consecutive patients treated with APC for hemorrhagic CRP from January 2013 to October 2017. Demographics, clinical variables, and typical endoscopic features were recorded independently. Success was defined as either cessation of bleeding or only occasional traces of bloody stools with no further treatments for at least 12 mo after the last APC treatment.We performed univariate and multivariate analyses to identify factors associated with success and risk factors for fistulas.RESULTS Forty-five patients with a median follow-up period of 24 mo(range: 12-67 mo)were enrolled. Fifteen(33.3%) patients required blood transfusion before APC.Successful treatment with APC was achieved in 31(68.9%) patients. The mean number of APC sessions was 1.3(1-3). Multivariate analysis showed that APC failure was independently associated with telangiectasias present on more than50% of the surface area [odds ratio(OR) = 6.53, 95% confidence interval(CI): 1.09-39.19, P = 0.04] and ulcerated area greater than 1 cm^2(OR = 8.15, 95%CI: 1.63-40.88, P = 0.01). Six(13.3%) patients had severe complications involving rectal fistulation. The only factor significantly associated with severe complications was ulcerated area greater than 1 cm^2(P = 0.035).CONCLUSION The long-term efficacy of APC for hemorrhagic CRP is uncertain in patients with telangiectasias present on > 50% of the surface area and ulceration > 1 cm^2.
文摘AIM: To report the long-term outcome of patients after complete ablation of non-neoplastic Barrett's esophagus (BE) with respect to BE relapse and development of intraepithelial neoplasia or esophageal adenocarcinoma. METHODS: In 70 patients with historically proven non neoplastic BE, complete BE ablation was achieved by argon plasma coagulation (APC) and high-dose proton pump inhibitor therapy (120 mg omeprazole daily). Sixty-six patients (94.4%) underwent further surveillance endoscopy. At each surveillance endoscopy four-quadrant biopsies were taken from the neo-squamous epithelium at 2 cm intervals depending on the pre-treatment length of BE mucosa beginning at the neo-Z-line, and from any endoscopically suspicious lesion. RESULTS: The median follow-up of 66 patients was 51 mo (range 9-85 mo) giving a total of 280.5 patient years. A mean of 6 biopsies were taken during surveillance endoscopies. In 13 patients (19.7%) tongues or islands suspicious for BE were found during endoscopy. In 8 of these patients (12.1%) non-neoplastic BE relapse was confirmed histologically giving a histological relapse rate of 3% per year. In none of the patients, intraepithelial neoplasia nor an esophageal adenocarcinoma was detected. Logistic regression analysis identified endoscopic detection of islands or tongues as the only positive predictor of BE relapse (P= 0.0004). CONCLUSION: The long-term relapse rate of non neoplastic BE following complete ablation with high-power APC is low (3% per year).
基金supported by the Chinese postdoctoral research fund,Major State Basic Research Program of China(G1999143201)special project of geological sciences(9801)of the State Planning Commission
文摘The Jinding superlarge lead and zinc deposit has attracted the attention of geologists of the world and its metallogenesis has long been in dispute. This paper takes the Jinding deposit and the Baiyangping Cu-Ag-Co deposit which was recently found at about 30 km north of Jinding as one ore belt, and, based on researches on the helium, argon, and xenon isotopic compositions of primary inclusions in ore-forming solutions of the main stage, the authors have found that the 3He/4He ratio of the ore-forming fluid is 2.7×10?6 (varying from 0.19 to 1.97 Ra), the 4He/40Ar ratio (0.24–3.12) is close to the mantle characteristic ratio, and the xenon isotopic composition and evolution show characters of the mantle xenon. The above results reveal the characteristics of mantle source and crust-mantle fluid mixing (mantle helium reaching 32%) and the metallogenic contributions of the deep processes in the Jinding-Baiyangping ore belt.
文摘AIM: This prospective study evaluated the effectiveness of 90 W argon plasma coagulation (APC) for the ablation of Barrett's esophagus (BE) that is considered to be the main risk factor for the development of esophageal adenocarcinoma.METHODS: The results from 25 patients, observed at the First Department of General Surgery, University of Verona, Italy, from October 2000 to October 2003, who underwent APC for histologically proven BE were prospectively analyzed.RESULTS: The ablation treatment was completed in all the patients but one (96%). The mean number of APC sessions needed to complete ablation was 1.6 (total number: 40). The eradication was obtained in the majority of cases by one session only (60%), two sessions were required in 24% of the cases and three or more in 16%.About 43% of the sessions were complicated. Retrosternal pain (22.5%) and fever (17.5%) were the most frequent symptoms. Only one major complication occurred, it was an hemorrhage due to ulcer formation on the treated esophagus that required urgent endoscopic sclerosis and admission. The follow-up was accomplished in all the patients with a mean period of 26.3 mo and 20 patients (84%) with a follow-up period longer than 24 mo. Only one patient showed a relapse of metaplastic mucosa 12 mo after the completion of ablation. The patient was hence re-treated and now is free from recurrence 33 mo later.CONCLUSION: High power setting (90 W) APC showed to be safe and effective. The effects persist at a mean follow-up period of two years with a comparable cost in term of complications with respect to standard power settings. Further studies with greater number of patients are required to confirm these results and to assess if ablation reduces the incidence of malignant progression.
基金The Special Basic Research Fund for Central Public Research Institutes (First Institute of Oceanograpgy,State Oceanic Administration)under contract No.GY02 -2008G38the Special Plan of Science and Technology Generalship in Qingdao under contract No.05-2 -JC-79the Special Project of Technical Foundational Work and Social Public Welfare Research under contract No.2003DIB3J114
文摘Based on the isotopic chronologic results of Cenozoic alkali basalts from the South China Sea, the characteristics of volcanic activi- ty of the South China Sea after spreading were studied. The potassium - argon ages of eight alkali basalt samples from the South China Sea, and the argon - argon ages of two samples among them are reported. Apparent ages of the whole rock are 3.80 to 7. 91 Ma with an average value of 5.43 Ma （potassium- argon, whole rock）, and there is little difference among samples at the same location, e. g. , 4. 76 - 5.78 Ma for location S（M-12. The argon - argon ages for the two samples are 6.06 and 4. 71 Ma, which lie within the age scope of potassium - argon method. The dating results indicate that rock-forming age is from late Miocene to Pliocene, which is consistent with erupting event for alkali basalts from adjacent regions of the South China Sea. Volcanic activities occur after the cessation of spreading of the South China Sea, which are controlled by lithospheric fault and the spreading center formed during the spreading period of the South China Sea. These dating results, combined with geochemical characteristics of these basalts, the published chronological data for the South China Sea and its adjacent regions, and the updated geophysical data near Hainan Island, suggest that after the cessation of spreading of the South China Sea, there occur widely distributing magmatic activities which primarily is alkali basalt, and the volcanic activity continues to Quaternary. The activity may be relative to Hainan mantle plume originated from core/mantle boundary.
基金This work was financially supported by the Department of Anesthesiology and Critical Care,Medical Center-University of Freiburg,GermanyThe article processing charge was funded by the Baden-Württemberg Ministry of Science,Research and Art and the University of Freiburg in the funding programme Open Access Publishing.
文摘We previously found that argon exerts its neuroprotective effect in part by inhibition of the toll-like receptors(TLR)2 and 4.The downstream transcription factors signal transducer and activator of transcription 3(STAT3)and nuclear factor kappa B(NF-κB)are also affected by argon and may play a role in neuroprotection.It also has been demonstrated that argon treatment could mitigate brain damage,reduce excessive microglial activation,and subsequently attenuate brain inflammation.Despite intensive research,the further exact mechanism remains unclear.In this study,human neuroblastoma cells were damaged in vitro with rotenone over a period of 4 hours(to mimic cerebral ischemia and reperfusion damage),followed by a 2-hour post-conditioning with argon(75%).In a separate in vivo experiment,retinal ischemia/reperfusion injury was induced in rats by increasing intraocular pressure for 1 hour.Upon reperfusion,argon was administered by inhalation for 2 hours.Argon reduced the binding of the transcription factors signal transducer and activator of transcription 3,nuclear factor kappa B,activator protein 1,and nuclear factor erythroid 2-related factor 2,which are involved in regulation of neuronal damage.Flow cytometry analysis showed that argon downregulated the Fas ligand.Some transcription factors were regulated by toll-like receptors;therefore,their effects could be eliminated,at least in part,by the TLR2 and TLR4 inhibitor oxidized phospholipid 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine(OxPAPC).Argon treatment reduced microglial activation after retinal ischemia/reperfusion injury.Subsequent quantitative polymerase chain reaction analysis revealed a reduction in the pro-inflammatory cytokines interleukin(IL-1α),IL-1β,IL-6,tumor necrosis factorα,and inducible nitric oxide synthase.Our results suggest that argon reduced the extent of inflammation in retinal neurons after ischemia/reperfusion injury by suppression of transcription factors crucial for microglial activation.Argon has no known side effects or narcotic properties;therefore,therapeutic use of this noble gas appears ideal for treatment of patients with neuronal damage in retinal ischemia/reperfusion injury.The animal experiments were approved by the Commission for Animal Care of the University of Freiburg(approval No.35-9185.81/G14-122)on October 19,2012.
基金Item Sponsored by National Natural Science Foundation of China and Baosteel Co(50674020)
文摘The flow field of molten steel and the interfacial behaviour between molten steel and liquid slag layer in medium-thin slab continuous casting mold with argon gas injection were studied by numerical simulation, in which the effects of nozzle submergence depth and port angle, casting speed, and argon gas flow rate on the flow and the level fluctuation of molten steel were considered. The results show that the molten steel is jetted from the submerged en- try nozzle （SEN） with three ports into the mold and forms three recirculation zones including one upper recireulation zone and two lower recirculation zones. Argon gas injection results in a secondary vortex flow in the upper zone near the nozzle. For a given casting speed and argon gas flow rate, increasing the side port angle and submergence depth of nozzle can effectively restrain the steel/slag interracial fluctuation. Increasing the casting speed would prick up the level fluctuation. For a fixed casting speed, argon gas flow rate has a critical value, the interracial fluctuation with argon gas injection are stronger than the case without argon gas injection when the argon gas flow rate is less than the critical value, but when the argon gas flow rate exceeds the critical value, the level fluctuation is calmer than that without argon gas injection.
基金the National Natural Science Foundation of China(Nos.51874215 and 51974213).
文摘In continuous casting,the argon blowing at the tundish upper nozzle is usually used to prevent nozzle clogging,whose effect is closely related to the migration of argon bubbles and the flow behavior of the liquid steel in the nozzle.Here,to investigate the effects of argon blowing at the tundish upper nozzle on multiphase flow behavior in nozzle,a threedimensional model of the tundish–nozzle–mold was established for numerical simulation.The results indicate that the argon bubbles injected from the inner wall of the tundish upper nozzle first move downward along the nozzle wall under the action of the liquid steel.As the distance from the tundish upper nozzle increases,the argon bubbles gradually diffuse to the center of the nozzle.Compared with no argon blowing,the liquid steel velocity increases in the center of the nozzle and decreases near the wall with argon blowing.With increasing the argon flow rate,the concentration of bubbles in the nozzle increases,and the process of bubble group diffusion to the center region of the nozzle speeds up.This in turn increases the liquid steel velocity at the center of the nozzle but reduces near the wall.With increasing the casting speed,the concentration of bubbles in the nozzle decreases,the length of the bubble group near the nozzle wall is extended,and the liquid steel velocity at the center region and near-wall region of the nozzle increases.The mechanism of argon blowing at the tundish upper nozzle to prevent nozzle clogging is mainly realized by the isolation effect of the argon bubble group on the inner wall of the nozzle.
基金Item Sponsored by National Natural Science Foundation of China (50674020)Program for New Century Excellent Talents in University (NCET-04-0285)
文摘The fluid flow and the interfacial phenomenon of slag and metal in tundish with gas blowing were studied with mathematical and physical modeling, and the effects of gas flowrate, the placement of porous beam for the generation of bubbles, and the combination of flow control devices on the flow and slag-metal interface were investigated. The results show that the position of gas bubbling has a significant effect on the flow in tundish, and the placement of porous beam and gas flowrate are the two main factors affecting the entrapment of slag in tundish. The closer the porous beam to the weir, the more reasonable is the flow, which is in favor of the control of slag entrapment in tundish.
