Enterogenic Stenotrophomonas maltophilia migrates to the mammary gland to induce mastitis by activating the calcium-ROS-AMPK-mTOR-autophagy pathway

Background Mastitis is an inflammatory disease of the mammary gland that has serious economic impacts on the dairy industry and endangers food safety.Our previous study found that the body has a gut/rumen-mammary gland axis and that disturbance of the gut/rumen microbiota could result in‘gastroenterogenic mastitis'.However,the mechanism has not been fully clarified.Recently,we found that long-term feeding of a high-concentrate diet induced mastitis in dairy cows,and the abundance of Stenotrophomonas maltophilia(S.maltophilia)was significantly increased in both the rumen and milk microbiota.Accordingly,we hypothesized that‘gastroenterogenic mastitis'can be induced by the migration of endogenous gut bacteria to the mammary gland.Therefore,this study investigated the mechanism by which enterogenic S.maltophilia induces mastitis.Results First,S.maltophilia was labelled with superfolder GFP and administered to mice via gavage.The results showed that treatment with S.maltophilia promoted the occurrence of mastitis and increased the permeability of the blood-milk barrier,leading to intestinal inflammation and intestinal leakage.Furthermore,tracking of ingested S.maltophilia revealed that S.maltophilia could migrate from the gut to the mammary gland and induce mastitis.Subsequently,mammary gland transcriptome analysis showed that the calcium and AMPK signalling pathways were significantly upregulated in mice treated with S.maltophilia.Then,using mouse mammary epithelial cells(MMECs),we verified that S.maltophilia induces mastitis through activation of the calcium-ROS-AMPK-mTOR-autophagy pathway.Conclusions In conclusion,the results showed that enterogenic S.maltophilia could migrate from the gut to the mammary gland via the gut-mammary axis and activate the calcium-ROS-AMPK-mTOR-autophagy pathway to induce mastitis.Targeting the gut-mammary gland axis may also be an effective method to treat mastitis.

New anti-mesenteric delta-shaped stapled anastomosis: Technical report with short-term postoperative outcomes in patients with Crohn’s disease

BACKGROUND Medical treatment for Crohn’s disease(CD)has continuously improved,which has led to a decrease in surgical recurrence rates.Despite these advancements,25%of patients will undergo repeat intestinal surgery.Recurrence of CD com-monly occurs on the mesentery side of the anastomosis site.AIM To compare the new anti-mesenteric side-to-side delta-shaped stapled anasto-mosis(DSA)with the conventional stapled functional end-to-end anastomosis(CSA).METHODS This retrospective study included CD patients who underwent ileo-ileal or ileo-colic anastomosis between January 2020 and December 2023.The DSA technique employed a stapler to maintain the concept of anti-mesentery side-to-side ana-stomosis by performing a 90°vertical closure of the open window compared with the CSA technique.At the corner where the open window is closed,the DSA avoids forming a pouch and creates an anastomosis resembling a delta shape within the intestinal lumen.We compared demographics,preoperative condition,operative findings,and operative outcomes for the two techniques.RESULTS The study included 175 patients,including 92 in the DSA group and 83 in the CSA group.The two groups were similar in baseline characteristics,preoperative medical treatment,and operative findings except for the Montreal classification location.The 30-days postoperative complication rate was signi-ficantly lower in the DSA group compared with the CSA group(16.3%vs 32.5%,P=0.009).Ileus incidence was significantly lower in the DSA group than in the CSA group(4.3%vs 14.5%,P=0.033),and the hospital stay was shorter in the DSA group than in the CSA group(5.67±1.53 days vs 7.39±3.68 days,P=0.001).CONCLUSION The DSA technique was feasible and showed comparable postoperative outcomes with lower short-term complic-ations compared with the CSA technique.Further studies on CD recurrence and long-term complications are warranted.

Endoscopic treatment of biliopancreatic pathology in patients with Whipple's pancreaticoduodenectomy surgical variants: Lessons learned from single-balloon enteroscopy-assisted ERCP

Background: Endoscopic treatment of biliopancreatic pathology is challenging due to surgically altered anatomy after Whipple's pancreaticoduodenectomy. This study aimed to evaluate the feasibility and safety of single-balloon enteroscopy-assisted endoscopic retrograde cholangiopancreatography(SBE-ERCP) to treat biliopancreatic pathology in patients with Whipple's pancreaticoduodenectomy surgical variants. Methods: We retrospectively analyzed 106 SBE-ERCP procedures in 46 patients with Whipple's variants. Technical and clinical success rates and adverse events were evaluated. Results: Biliary SBE-ERCP was performed in 34 patients and pancreatic SBE-ERCP in 17, including 5 with both indications. From a total of 106 SBE-ERCP procedures, 76 were biliary indication with technical success rate of 68/76(90%) procedures and clinical success rate of 30/34(88%) patients. Mild adverse event rate was 8/76(11%), without serious adverse events. From a total of 106 SBE-ERCP procedures, 30 were pancreatic indication with technical success rate of 24/30(80%) procedures( P = 0.194 vs. biliary SBEERCP) and clinical success rate of 11/17(65%) patients( P = 0.016 vs. biliary SBE-ERCP). Mild adverse event rate was 6/30(20%)( P = 0.194 vs. biliary SBE-ERCP), without serious adverse events. After SBE-ERCP failure, endoscopic ultrasound-guided drainage, percutaneous drainage and redo surgery were alternative therapeutic options. Conclusions: Biliopancreatic pathology after Whipple's pancreaticoduodenectomy variants can be treated using SBE-ERCP without serious adverse events. Technical and clinical success rates are high for biliary indications, whereas clinical success rate of pancreatic indications is significantly lower. SBE-ERCP can be considered as first-line treatment option in this patient group with surgically altered anatomy.

Enterococcus faecalis provides protection during scavenging in carrion crow (Corvus corone)

The gut microbiota significantly influences host physiology and provides essential ecosystem services.While diet can affect the composition of the gut microbiota,the gut microbiota can also help the host adapt to specific dietary habits.The carrion crow(Corvus corone),an urban facultative scavenger bird,hosts an abundance of pathogens due to its scavenging behavior.Despite this,carrion crows infrequently exhibit illness,a phenomenon related to their unique physiological adaptability.At present,however,the role of the gut microbiota remains incompletely understood.In this study,we performed a comparative analysis using 16S rRNA amplicon sequencing technology to assess colonic content in carrion crows and 16 other bird species with different diets in Beijing,China.Our findings revealed that the dominant gut microbiota in carrion crows was primarily composed of Proteobacteria(75.51%)and Firmicutes(22.37%).Significant differences were observed in the relative abundance of Enterococcus faecalis among groups,highlighting its potential as a biomarker of facultative scavenging behavior in carrion crows.Subsequently,E.faecalis isolated from carrion crows was transplanted into model mice to explore the protective effects of this bacterial community against Salmonella enterica infection.Results showed that E.faecalis down-regulated the expression of pro-inflammatory cytokines tumor necrosis factor alpha(TNF-α),interferon gamma(IFN-γ),and interleukin 6(IL-6),prevented S.enterica colonization,and regulated the composition of gut microbiota in mice,thereby modulating the host’s immune regulatory capacity.Therefore,E.faecalis exerts immunoregulatory and anti-pathogenic functions in carrion crows engaged in scavenging behavior,offering a representative case of how the gut microbiota contributes to the protection of hosts with specialized diets.

Hybrid argon plasma coagulation for the treatment of Barrett’s esophagus:A prospective,multicenter study

BACKGROUND The incidence of Barrett’s esophagus(BE)in China is lower compared to the Western populations.Hence,studies conducted in the Chinese population has been limited.The current treatment options available for BE treatment includes argon plasma coagulation(APC),radiofrequency ablation and cryoablation,all with varying degrees of success.AIM To determine the efficacy and safety of HybridAPC in the treatment of BE.METHODS The study cohort consisted of patients with BE who underwent HybridAPC ablation treatment.These procedures were performed by seven endoscopists from different tertiary hospitals.The duration of the procedure,curative rate,complications and recurrent rate by 1-year follow-up were recorded.RESULTS Eighty individuals were enrolled for treatment from July 2017 to June 2020,comprising of 39 males and 41 females with a median age of 54 years(range,30 to 83 years).The technical success rate of HybridAPC was 100%and the overall curative rate was 98.15%.No severe complications occurred during the operation.BE cases were classified as short-segment BE and long-segment BE.Patients with short-segment BE were all considered cured without complications.Thirty-six patients completed the one-year follow-up without recurrence.Twenty-four percent had mild dysplasia which were all resolved with one post-procedural treatment.The mean duration of the procedure was 10.94±6.52 min.CONCLUSION Treatment of BE with HybridAPC was found to be a simple and quick procedure that is safe and effective during the short-term follow-up,especially in cases of short-segment BE.This technique could be considered as a feasible alternative ablation therapy for BE.

Dynamic ultrasonography for optimizing treatment position in superior mesenteric artery syndrome:Two case reports and review of literature

BACKGROUND Superior mesenteric artery(SMA)syndrome is a rare cause of duodenal obstruction by extrinsic compression between the SMA and the aorta(SMA-Ao).Although the left lateral recumbent position is considered effective in the treatment of SMA syndrome,individual variations in the optimal patient position have been noted.In this report,we present two elderly cases of SMA syndrome that exhibited rapid recovery due to ultrasonographic dynamic evaluation of the optimal position for each patient.CASE SUMMARY Case 1:A 90-year-old man with nausea and vomiting.Following diagnosis of SMA syndrome by computed tomography(CT),ultrasonography(US)revealed the SMA-Ao distance in the supine position(4 mm),which slightly improved in the lateral position(5.7–7.0 mm)without the passage of duodenal contents.However,in the sitting position,the SMA-Ao distance was increased to 15 mm accompanied by improved content passage.Additionally,US indicated enhanced passage upon abdominal massage on the right side.By day 2,the patient could eat comfortably with the optimal position and massage.Case 2:An 87-year-old woman with vomiting.After the diagnosis of SMA syndrome and aspiration pneumonia by CT,dynamic US confirmed the optimal position(SMA-Ao distance was improved to 7 mm in forward-bent position,whereas it remained at 5 mm in the supine position).By day 7 when her pneumonia recovered,she could eat with the optimal position.CONCLUSION The optimal position for SMA syndrome varies among individuals.Dynamic US appears to be a valuable tool in improving patient outcomes.

Surgical treatment of inflammatory bowel disease:From the gastroenterologist’s stand-point

Treatment of ulcerative colitis(UC)and Crohn’s disease(CD)represents,in the majority of cases,a real challenge to the gastroenterologist’s abilities and skills as well as a clinical test concerning his/her levels of medical knowledge and experience.During the last two decades,our pharmaceutical arsenal was significantly strengthened,especially after the introduction of the so-called biological agents,drugs which to a large extent not only improved the results of conservative treatment but also changed the natural history of the disease.However,colectomy is still necessary for some patients with severe UC although smaller compared to the past,precisely because of the improvements achieved in the available conservative treatment.Nevertheless,surgeries to treat colon dysplasia and cancer are increasing to some extent.At the same time,satisfactory improvements in surgical techniques,the pre-and post-operative care of patients,as well as the selection of the appropriate time for performing the surgery have been noticed.Regarding patients with CD,the improvement of conservative treatment did not significantly change the need for surgical treatment since two-thirds of patients need to undergo surgery at some point in the course of their disease.On the other hand,the outcome of the operation has improved through good preoperative care as well as the wide application of more conservative surgical techniques aimed at keeping as much of the bowel in situ as possible.This article discusses the indications for surgical management of UC patients from the gastroenterologist’s point of view,the results of the emerging new techniques such as transanal surgery and robotics,as well as alternative operations to the classic ileo-anal-pouch anastomosis.The author also discusses the basic principles of surgical management of patients with CD based on the results of the relevant literature.The self-evident is emphasized,that is,to achieve an excellent therapeutic result in patients with severe inflammatory bowel disease in today’s era;the close cooperation of gastroenterologists with surgeons,pathologists,imaging,and nutritionists is of paramount importance.

Appendicitis combined with Meckel’s diverticulum obstruction, perforation, and inflammation in children: Three case reports

BACKGROUND Meckel’s diverticulum is a common congenital malformation of the small intestine,with the three most common complications being obstruction,per-foration,and inflammation.To date,only a few cases have been reported world-wide.In children,the clinical symptoms are similar to appendicitis.As most of the imaging features are nonspecific,the preoperative diagnosis is not precise.In addition,the clinical characteristics are highly similar to pediatric acute appendicitis,thus special attention is necessary to distinguish Meckel’s diver-ticulum from pediatric appendicitis.Patients with poor disease control should undergo laparoscopic exploration to avoid serious complications,including intestinal necrosis,intestinal perforation and gastrointestinal bleeding.CASE SUMMARY This report presents three cases of appendicitis in children combined with intestinal obstruction,which was caused by fibrous bands(ligaments)arising from the top part of Meckel's diverticulum,diverticular perforation,and diver-ticular inflammation.All three patients,aged 11-12 years,had acute appendicitis as their initial clinical presentation.All were treated by laparoscopic surgery with a favorable outcome.A complete dataset including clinical presentation,dia-gnostic imaging,surgical information,and histopathologic findings was also provided.CONCLUSION Preoperative diagnosis of Meckel’s diverticulum and its complications is challenging because its clinical signs and complications are similar to those of appendicitis in children.Laparoscopy combined with laparotomy is useful for diagnosis and treatment.

The Three Principles of Institutional Safeguards for Women's Participation in Legislation in China

The participation of women in legislation is an important aspect and means of safeguarding women’s rights.Feminist theory,based on criticism of both the“citizenship identity theory as rights”and the“citizenship identity theory as responsibilities,”proposes the“citizenship identity theory as subjectivity.”Observing the current practice of women’s participation in legislation in China,two institutional safeguard principles can be summarized:the“minimum proportion”and the“influence evaluation.”However,each of these principles has its inherent limitations.Therefore,it is necessary to supplement them with the principle of“subjective participation”in a reflective manner.This principle requires women to participate substantively in the legislative process as subjects,express women’s needs and demands,input women’s perspectives and experiences,and reconstruct the distribution of rights and responsibilities in the existing legislation.The three principles complement each other and work together to comprehensively constitute the institutional structure of women’s participation in legislation,thereby promoting the reproduction of corresponding action structures.

Single-center retrospective study of the diagnostic value of doubleballoon enteroscopy in Meckel’s diverticulum with bleeding

BACKGROUND The study aimed to analyze the characteristic clinical manifestations of patients with intestinal disease Meckel’s diverticulum(MD)complicated by digestive tract hemorrhage.Moreover,we aimed to evaluate the value of double-balloon enteroscopy(DBE)in MD diagnosis and the prognosis after laparoscopic diverticula resection.AIM To evaluate the value of DBE in the diagnosis and the prognosis after laparoscopic diverticula resection for MD with bleeding.METHODS The study retrospectively analyzed relevant data from 84 MD patients treated between January 2015 and March 2022 and recorded their clinical manifestations,auxiliary examination,and follow-up after laparoscopic resection of diverticula.RESULTS(1)Among 84 MD patients complicated with hemorrhage,77 were male,and 7 were female with an average age of 31.31±10.75 years.The incidence was higher in men than in women of different ages;(2)Among the 84 MD patients,65(78.40%)had defecated dark red stools,and 50(58.80%)had no accompanying symptoms during bleeding,indicating that most MD bleeding appeared a dark red stool without accompanying symptoms;(3)The shock index of 71 patients(85.20%)was<1,suggesting that the blood loss of most MD patients was less than 20%–30%,and only a few patients had a blood loss of>30%;(4)The DBE-positive rate was 100%(54/54),99mTcpertechnetate-positive scanning rate was 78%(35/45)compared with capsule endoscopy(36%)and small intestine computed tomography(19%).These results suggest that DBE and 99mTc-pertechnetate scans had significant advantages in diagnosing MD and bleeding,especially DBE was a highly precise examination method in MD diagnosis;(5)A total of 54 MD patients with hemorrhage underwent DBE examination before surgery.DBE endoscopy revealed many mucosal manifestations including normal appearance,inflammatory changes,ulcerative changes,diverticulum inversion,and nodular hyperplasia,with ulcerative changes being the most common(53.70%).This suggests that diverticular mucosal ulcer was the main cause of MD and bleeding;and(6)Laparoscopic dissection of diverticulae was performed in 76 patients,The patients who underwent postoperative follow-up did not experience any further bleeding.Additionally,follow-up examination of the 8 cases who had declined surgery revealed that 3 of them experienced a recurrence of digestive tract bleeding.These findings indicate that laparoscopic diverticula resection in MD patients complicated by bleeding had a favorable prognosis.CONCLUSION Bleeding associated with MD was predominantly observed in male adolescents,particularly at a young age.DBE was a highly precise examination method in MD diagnosis.Laparoscopic diverticula resection effectively prevented MD bleeding and had a good prognosis.

Data from Twenty-Three FRB’s Confirm the Universe Is Static and Not Expanding

Fast Radio Bursts from far away galaxies have travelled through the IGM and provide a tool to study its composition. Presently there are 23 FRB’s whose host galaxies have been identified and the redshift found. This gives us the opportunity to test Dispersion Measure versus redshift predictions made by two models. The Macquart relation for an expanding Universe and the New Tired Light relationship in a static universe. In New Tired Light, redshifts are produced when a photon is absorbed and re-emitted by the electrons in the IGM which recoil on both occasions. Some of the energy of the photon has been transferred to the kinetic energy of the recoiling electron. The photon has less energy, a lower frequency and a longer wavelength. It has been redshifted. Since dispersion is due to an interaction between radio signals and these same electrons one would expect a direct relationship between DM and redshift in the New Tired light model. The relation is DM=(mec/2hre)ln(1+z)and contains no adjustable parameters—just a combination of universal constants related to the electron and photon. Notice that the relation is independent of the electron number density ne since a change in ne affects both the DM and redshift equally. A graph of DM versus ln(1 + z) will be a straight line of gradient (mec/2hre)and, using SI units, substituting for the constants gives 7.318 × 1025 m−2. Using the data from the 23 well localized FRB’s, with the weighting of the DM’s for expansion removed (so that the data corresponds to a static universe), a graph of DM versus ln(1 + z) has a gradient of 6.7 × 1025 m−2—9% below the predicted (mec/2hre). The Macquart relation involves highly processed data and adjustable parameters to allow for “dark energy” and “dark matter” (neither of which has yet been found) and can be reduced to DM = 850z (in units of pc∙cm−3). Using the data from this set of localized FRB’s gives a trendline with gradient 1.10 × 103 pc∙cm−3—almost 30% higher than that predicted in an expanding universe model. The FRB data clearly comes down in favour of a static universe rather than an expanding one. Combining the DM-z relationship for the 23 well localized FRB’s, with the Hubble diagram, drawn using the NED-D compilation of redshift independent extragalactic distances, produces a value of “ne” the mean electron number density of the IGM, of ne=0.48 m−3close to the value ne=0.5 m−3, long since predicted by NTL.

Fournier’s Gangrene: 13-Year Experience in a Tertiary Center, North Eastern Nigeria

Background: Fournier’s gangrene is a fulminant infection of the genitourinary tract characterized by progressive necrosis of the skin and subcutaneous tissue of the external genitalia. Initially mainly seen involving the scrotum of elderly men with different moods of occurrence each unpleasantly lethal. With varying types of presentation only one thing has remained constant;the poor prognosis of this condition. Purpose/Aim: Thus, it’s important to study the trends of the presentation of this condition laying emphasis on the challenges in the management of these patients;both the negative and positive prognostic factors. Materials and Methods: Urology ward record books, clinic record books and operating theater records were used to identify patients managed for Fournier gangrene in ATBUTH Bauchi. A retrospective study of the medical files of all the patients managed from January 2011 to January 2024 was done. Data was analyzed using SPSS version 29. Results: Data from 47 patients seen during the period of study were carefully collected and analyzed. The age range is 2 weeks to 97 years. There were two neonates, one at 2nd week of life and the other at 3rd week. Mortality rate is 36%. The average time duration before presentation for patients that died was two weeks, a minimum of 9 days prior to presentation and a maximum of 21 days, about 10 of which came in septic shock and the remaining presented with fever and very extensive necrotizing fasciitis of the perineum. All the patients that died had diabetes mellitus as a comorbidity except the neonate. All the patients that survived were much younger, all were below 60 years of age (2 weeks - 53 years). Conclusion: Here, we share our experience managing patients with Fournier’s gangrene in our facility in the past 13-year period from January 2011 to January 2024. .

The Criteria for Reducing Centrally Restricted Three-Body Problem to Two-Body Problem

Our Solar System contains eight planets and their respective natural satellites excepting the inner two planets Mercury and Venus. A satellite hosted by a given Planet is well protected by the gravitational pertubation of much heavier planets such as Jupiter and Saturn if the natural satellite lies deep inside the respective host Planet Hill sphere. Each planet has a Hill radius aH and planet mean radius RP and the ratio R1=RP/aH. Under very low R1 (less than 0.006) the approximation of CRTBP (centrally restricted three-body problem) to two-body problem is valid and planet has spacious Hill lobe to capture a satellite and retain it. This ensures a high probability of capture of natural satellite by the given planet and Sun’s perturbation on Planet-Satellite binary can be neglected. This is the case with Earth, Mars, Jupiter, Saturn, Neptune and Uranus. But Mercury and Venus has R1=RP/aH =0.01 and 5.9862 × 10-3 respectively hence they have no satellites. There is a limit to the dimension of the captured body. It must be a much smaller body both dimensionally as well masswise. The qantitative limit is a subject of an independent study.

Existence of Monotone Positive Solution for a Fourth-Order Three-Point BVP with Sign-Changing Green’s Function

This paper is concerned with the following fourth-order three-point boundary value problem , where , we discuss the existence of positive solutions to the above problem by applying to the fixed point theory in cones and iterative technique.

Manual Order Picking Route Optimization in Distribution Warehouse of Chain Furniture Retail Enterprise

Due to the effects of the COVID-19 pandemic and the rise of online shopping, the offline sales of IKEA Fuzhou have been declining since 2020. Because the cost of distribution warehouse is a major expense for offline chain furniture retailers, and the picking process is a key activity in distribution warehouse operations. To reduce the cost of distribution warehouse and alleviate the survival pressure of the offline chain furniture retailers, this paper focuses on optimizing the picking route of the IKEA Fuzhou distribution warehouse. It starts by creating a two-dimensional coordinate system for the storage location of the distribution warehouse using the traditional S-type picking strategy to calculate the distance and time of the sorting route. Then, the problem of optimizing the picking route is then transformed into the travelling salesman problem (TSP), and picking route optimization model is developed using a genetic algorithm to analyze the sorting efficiency and picking route optimization. Results show that the order-picking route using the genetic algorithm strategy is significantly better than the traditional S-type picking strategy, which can improve overall sorting efficiency and operations, reduce costs, and increase efficiency. Thus, this establishes an implementation process for the order-picking path based on genetic algorithm optimization to improve overall sorting efficiency and operations, reduce costs, increase efficiency, and alleviate the survival pressure of pandemic-affected enterprises.

宽负荷下切圆燃煤锅炉H_(2)S分布特性的数值模拟

锅炉采用空气分级燃烧降低NO_(x)排放的同时也提高了主燃区H_(2)S体积分数。炉墙壁面过高的H_(2)S体积分数是加剧水冷壁高温腐蚀的重要因素。为保障新能源并网发电,大型燃煤机组灵活调峰的需求增加,不同负荷下的水冷壁近壁面H_(2)S分布特性值得关注。通过正交试验分析了切圆燃煤锅炉运行参数对水冷壁近壁面H_(2)S体积分数分布的影响。选取一台超临界600 MW切圆燃煤锅炉建立数值模型,设计L_(16)(4^(5))正交工况,覆盖100%BMCR、75%THA,50%THA以及35%BMCR四种负荷。建立了自定义SO_(x)生成模型以确定燃料硫的析出和转化路径,模型包含多表面反应子模型以描述焦炭与O_(2)/CO_(2)/H_(2)O等3种气体的异相反应,并确定焦炭气化反应消耗量占总消耗量的比例,进而对炉膛H_(2)S空间分布进行了模拟计算。研究表明,近壁面高体积分数H_(2)S区域主要位于投运燃烧器层中最下层燃烧器以下以及最上层燃烧器以上至SOFA层之间,烟气切圆沿炉膛高度增加逐渐增大是造成后一区域H_(2)S体积分数较高的重要原因。35%BMCR负荷下水冷壁重点区域的H_(2)S平均体积分数为364μL/L,明显低于其他负荷。锅炉运行参数对重点区域H_(2)S体积分数影响程度的排序为:锅炉负荷>一次风率>主燃区空气过量系数>假想切圆直径>燃烧器竖直摆角。

改变导叶翼型对水泵水轮机“S”特性的影响

针对水泵水轮机“S”特性区域的不稳定性问题,提出使用改型活动导叶翼型进行性能提升.以某水泵水轮机模型为研究对象,采用SST k-ω湍流模型对水泵水轮机全流道进行三维数值计算,通过对活动导叶翼型的改型设计,得出流量-转速模拟曲线,分析水泵水轮机组“S”特性改善情况.将计算与试验结果进行对比,并对改型活动导叶翼型前后机组的无叶区进行压力脉动分析.结果表明:在保证整体效率依然保持在92%附近的前提下,新的活动导叶翼型对机组的“S”特性依旧具有改善效果;无叶区压力脉动主要是受到活动导叶叶栅区域的分流在此重新聚集影响,并且与转轮叶片的动静相互扰动引起的;改型后的活动导叶降低了无叶区的压力脉动幅值,提升了水泵水轮机运行中的并网稳定性.

S型异质结光催化剂ZnFe_(2)O_(4)/WO_(3)的构筑及光催化还原CO_(2)性能

通过在WO_(3)纳米片表面负载ZnFe_(2)O_(4)纳米颗粒,构建了一系列S型异质结光催化剂ZnFe_(2)O_(4)/WO_(3),并研究了其光催化CO_(2)还原性能。在没有助催化剂和牺牲剂的条件下,所制备的ZnFe_(2)O_(4)/WO_(3)复合材料可对CO_(2)与水蒸汽进行光催化反应。优化后的材料光照5 h后CO_(2)还原产物CO和CH_(4)的产量分别为7.87和4.88μmol·g^(-1)。相对于单相组分,CO和CH_(4)的产量明显提高。光催化活性的提高,归因于ZnFe_(2)O_(4)和WO_(3)异质结的形成以及光生载流子的S型电荷传输模式。

基于STM32的步进电机加减速轨迹规划算法

针对传统步进电机开环控制下加减速过程中柔性冲击大、失步和过冲等问题,结合STM32单片机提出了一种离散化的、带有电流调节的S曲线加减速控制算法。首先,通过多项式算法构建连续光滑的S曲线,根据矩频特性拟合转速和转矩的关系,联立转速和功率的关系,推导出电流计算方法;然后,对连续的S曲线进行等时间间隔采样,完成对S曲线的离散化;最后,在Keil平台进行算法代码编写,将编译后的工程文件下载到STM32中,通过步进电机的速度和位置跟踪实验验证了算法的有效性。

2022年四川芦山M_(S)6.1地震前应力状态研究

为研究2022年6月1日四川芦山M_(S)6.1地震的孕育和发生过程,采用CAP方法反演了2013年芦山M_(S)7.0主震及M_(S)≥5.0余震的震源机制解,并基于应力张量方差与b值时空分布特征,探讨了芦山M_(S)6.1地震的力学机制和震源区的应力状态。结果表明:2022年芦山M_(S)6.1地震震源机制表现出与2013年芦山M_(S)7.0主震和5级余震相似的逆冲型破裂特征,压应力轴方位与龙门山断裂带南段区域应力场一致。2013年芦山M_(S)7.0地震后震中及附近的应力张量方差和b值长期处于低值状态,2022年芦山M_(S)6.1地震前震中及附近出现了应力张量方差和b值的低值异常,表明芦山余震区处于较高的应力水平。分析认为:巴颜喀拉块体持续东向运动受到华南块体的阻挡,震中所在区域长期受挤压逆冲作用,从而使芦山余震区长期处于应力积累的状态,芦山M_(S)6.1地震也是在这种动力学背景下发生的。