Experimental investigation of key parameters pertinent to multi-hole orifice throttling characteristic

This study firstly defines a set of arrangement rule for perforated holes of multi-hole orifice(MO), and then presents three critical geometrical parameters including total number of performated hole, equivalent diameter ratio and distribution density of perforated holes, which are to quantify MO structure. This paper built the throttling test apparatus for nice test MO plates, which were designed according to orthogonal theory. The experiments were conducted to investigate the effect of three critical geometerical parameters on the pressure loss coefficient of test MOs. Results show that equivalent diameter ratio is the dominant prameter affecting MO throttling characterstic.

Influence of the Hole Chamfer on the Characteristics of a Multi-hole Orifice Flowmeter

In order to analyze the influence of the hole chamfer on the metering performances of a Multi-hole Orifice Flowmeter and optimize the related orifice structure,a multi-hole orifice flowmeter with DN80 and throttle ratio of 0.45 was considered in the present study.The flow field characteristics were determined in the framework of a CFD technique.The results show that the multi-hole orifice flowmeter with filleting transition around the throttle orifice has higher accuracy in a wide range of the space of parameters,and is more suitable for accurate measurement of fluid in process control.

Experimental study of a simple pressure loss coefficient model for multi-hole orifice

A throttling experiment for the multi-hole orifice （MO） using water was conducted based on the conclusion of key parameters affecting the MO throttling performance. Testing MOs and standard orifice plates （ SO ） were designed for the throttling experiment to compare the throttling effect using the equivalent diameter ratio （RED） and diameter ratio （RD ） as key parameters, respectively. Meanwhile, effective metrical conditions were provided for experimental accuracy. The throttling model form was determined according to the theoretical throttling model of SO. Then the unknown parameters involved were identified by experimental data. A good concordance between the modeling computation and experimental results shows a validation of the MO throtting model.

Two big orifices in the second duodenal portion:A case of an atypical double papilla

With the advent of endoscopic retrograde cholangiopancreatography(ERCP)in the early 1970s,anatomic anomalies of the Vaterian system were described endoscopically[1].Although the occurrence is rare,the common bile duct(CBD)and the pancreatic duct may fail to coalesce during embryologic development.This leads to double major papilla because both ducts open into the duodenum separately[1].In this way the cranial duct communicates with the CBD,while the caudal orifice communicates with the pancreatic duct[2].

Wetting front migration model of ion-adsorption rare earth during the multi-hole unsaturated liquid injection

In the process of ion-adsorption rare earth ore leaching,the migration characteristics of the wetting front in multi-hole injection holes and the influence of wetting front intersection effect on the migration distance of wetting fronts are still unclear.Besides,wetting front migration distance and leaching time are usually required to optimize the leaching process.In this study,wetting front migration tests of ionadsorption rare earth ores during the multi-hole fluid injection(the spacing between injection holes was 10 cm,12 cm and 14 cm)and single-hole fluid injection were completed under the constant water head height.At the pre-intersection stage,the wetting front migration laws of ion-adsorption rare earth ores during the multi-hole fluid injection and single-hole fluid injection were identical.At the postintersection stage,the intersection accelerated the wetting front migration.By using the Darcy’s law,the intersection effect of wetting fronts during the multi-hole liquid injection was transformed into the water head height directly above the intersection.Finally,based on the Green-Ampt model,a wetting front migration model of ion-adsorption rare earth ores during the multi-hole unsaturated liquid injection was established.Error analysis results showed that the proposed model can accurately simulate the infiltration process under experimental conditions.The research results enrich the infiltration law and theory of ion-adsorption rare earth ores during the multi-hole liquid injection,and this study provides a scientific basis for optimizing the liquid injection well pattern parameters of ion-adsorption rare earth in situ leaching in the future.

Removal of a guide-wire sliding into abdominal cavity via transgastric natural orifice transluminal endoscopic surgery: A case report

BACKGROUND Guidewire slippage into the peritoneal cavity during clinical operations is extremely rare.Therefore,this paper aims to report a successful case of guidewire removal using transgastric natural orifice transluminal endoscopic surgery(NOTES).The goal is to enhance physicians'understanding of the management plan for this unique scenario and provide a valuable reference for clinical practice.CASE SUMMARY A 64-year-old man presented with abdominal distension and was diagnosed with cirrhosis combined with massive ascites.To proceed with treatment,the patient underwent ultrasound-guided peritoneal puncture and underwent catheterization and drainage.Unfortunately,a 0.035-inch guidewire slipped into the abdominal cavity during the procedure.Following a comprehensive evaluation and consultation by a multidisciplinary team,the guidewire was successfully removed using NOTES.CONCLUSION This case highlights the potential consideration of transgastric NOTES removal when encountering a foreign body,such as a guidewire,within the abdominal cavity.

Resection of polyps involving the appendiceal orifice by combined endo-laparoscopic surgery: Two case reports

BACKGROUND The management of polyps involving the appendiceal orifice(AO)presents notable challenges.Endoscopic resection is frequently hindered by operational complexities,a heightened risk of incomplete removal,and an elevated risk of procedural complications,including appendicitis.Conversely,surgical resection may entail unnecessary excision of intestinal segments,leading to potential morbidity.CASE SUMMARY Here,we reported two patients who presented with polyps deeply situated within the AO,with indistinct boundaries making it challenging to ensure completeness using traditional endoscopic resection.To overcome these challenges,we em-ployed combined endo-laparoscopic surgery(CELS),achieving curative resection without postoperative complications.CONCLUSION The application of CELS in managing polyps involving the AO is emerging as a safe and effective treatment modality.

Analysis of quality of life in patients after transgastric natural orifice transluminal endoscopic gallbladder-preserving surgery

BACKGROUND At present,laparoscopic cholecystectomy(LC)is the main surgical treatment for gallstones.But,after gallbladder removal,there are many complications.Therefore,it is hoped to remove stones while preserving the function of the gallbladder,and with the development of endoscopic technology,natural orifice transluminal endoscopic surgery came into being.AIM To compare the quality of life,perioperative indicators,adverse events after LC and transgastric natural orifice transluminal endoscopic gallbladder-preserving surgery(EGPS)in patients with gallstones.METHODS Patients who were admitted to The First Affiliated Hospital of Xinjiang Medical University from 2020 to 2022 were retrospectively collected.We adopted propen-sity score matching(1:1)to compare EGPS and LC patients.RESULTS A total of 662 cases were collected,of which 589 cases underwent LC,and 73 cases underwent EGPS.Propensity score matching was performed,and 40 patients were included in each of the groups.In the EGPS group,except the gastr-ointestinal defecation(P=0.603),the total score,physical well-being,mental well-being,and gastrointestinal digestion were statistically significant compared with the preoperative score after surgery(P<0.05).In the LC group,except the mental well-being,the total score,physical well-being,gastrointestinal digestion,the gastrointestinal defecation was statistically significant compared with the preoperative score after surgery(P<0.05).When comparing between groups,gastrointestinal defecation had significantly difference(P=0.002)between the two groups,there was no statistically significant difference in the total postoperative score and the other three subscales.In the surgery duration,hospital stay and cost,LC group were lower than EGPS group.The recurrence factors of gallstones after EGPS were analyzed:and recurrence was not correlated with gender,age,body mass index,number of stones,and preoperative score.CONCLUSION Whether EGPS or LC,it can improve the patient’s symptoms,and the EGPS has less impact on the patient’s defecation.It needed to,prospective,multicenter,long-term follow-up,large-sample related studies to prove.

Robotic natural orifice specimen extraction surgery I-type F method vs conventional robotic resection for lower rectal cancer

BACKGROUND Robotic resection using the natural orifice specimen extraction surgery I-type F method(R-NOSES I-F)is a novel minimally invasive surgical strategy for the treatment of lower rectal cancer.However,the current literature on this method is limited to case reports,and further investigation into its safety and feasibility is warranted.AIM To evaluate the safety and feasibility of R-NOSES I-F for the treatment of low rectal cancer.METHODS From September 2018 to February 2022,206 patients diagnosed with low rectal cancer at First Affiliated Hospital of Nanchang University were included in this retrospective analysis.Of these patients,22 underwent R-NOSES I-F surgery(RNOSES I-F group)and 76 underwent conventional robotic-assisted low rectal cancer resection(RLRC group).Clinicopathological data of all patients were collected and analyzed.Postoperative outcomes and prognoses were compared between the two groups.Statistical analysis was performed using SPSS software.RESULTS Patients in the R-NOSES I-F group had a significantly lower visual analog score for pain on postoperative day 1(1.7±0.7 vs 2.2±0.6,P=0.003)and shorter postoperative anal venting time(2.7±0.6 vs 3.5±0.7,P<0.001)than those in the RLRC group.There were no significant differences between the two groups in terms of sex,age,body mass index,tumor size,TNM stage,operative time,intrao-perative bleeding,postoperative complications,or inflammatory response(P>0.05).Postoperative anal and urinary functions,as assessed by Wexner,low anterior resection syndrome,and International Prostate Symptom Scale scores,were similar in both groups(P>0.05).Long-term follow-up revealed no significant differences in the rates of local recurrence and distant metastasis between the two groups(P>0.05).CONCLUSION R-NOSES I-F is a safe and effective minimally invasive procedure for the treatment of lower rectal cancer.It improves pain relief,promotes gastrointestinal function recovery,and helps avoid incision-related complications.

Expanding endoscopic boundaries:Endoscopic resection of large appendiceal orifice polyps with endoscopic mucosal resection and endoscopic submucosal dissection

BACKGROUND Large appendiceal orifice polyps are traditionally treated surgically.Recently,endoscopic mucosal resection(EMR)and endoscopic submucosal dissection(ESD)have been utilized as alternative resection techniques.AIM To evaluate the efficacy and safety of endoscopic resection techniques for the management of large appendiceal orifice polyps.METHODS This was a retrospective observational study conducted to assess the feasibility and safety of EMR and ESD for large appendiceal orifice polyps.This project was approved by the Baylor College of Medicine Institutional Review Board.Patients who underwent endoscopic resection of appendiceal orifice polyps≥1 cm from 2015 to 2022 at a tertiary referral endoscopy center in the United States were enrolled.The main outcomes of this study included en bloc resection,R0 resection,post resection adverse events,and polyp recurrence.RESULTS A total of 19 patients were identified.Most patients were female(53%)and Caucasian(95%).The mean age was 63.3±10.8 years,and the average body mass index was 28.8±6.4.The mean polyp size was 25.5±14.2 mm.74%of polyps were localized to the appendix(at or inside the appendiceal orifice)and the remaining extended into the cecum.68%of polyps occupied≥50%of the appendiceal orifice circumference.The mean procedure duration was 61.6±37.9 minutes.Polyps were resected via endoscopic mucosal resection,endoscopic submucosal dissection,and hybrid procedures in 5,6,and 8 patients,respectively.Final pathology was remarkable for tubular adenoma(n=10)[one with high grade dysplasia],sessile serrated adenoma(n=7),and tubulovillous adenoma(n=2)[two with high grade dysplasia].En bloc resection was achieved in 84%with an 88%R0 resection rate.Despite the large polyp sizes and challenging procedures,89%(n=17)of patients were discharged on the same day as their procedure.Two patients were admitted for post-procedure observation for conservative pain management.Eight patients underwent repeat colonoscopy without evidence of residual or recurrent adenomatous polyps.CONCLUSION Our study highlights how endoscopic mucosal resection,endoscopic submucosal dissection,and hybrid procedures are all appropriate techniques with minimal adverse effects,further validating the utility of endoscopic procedures in the management of large appendiceal polyps.

Novel deformable self-assembled magnetic anastomosis ring for endoscopic treatment of colonic stenosis via natural orifice

BACKGROUND Although endoscope-assisted magnetic compression anastomosis has already been reported for colonic anastomosis,there is no report on a single-approach operation using the natural orifice.AIM To design a deformable self-assembled magnetic anastomosis ring(DSAMAR)for colonic anastomosis for use in single-approach operation and evaluate its feasibility and safety through animal experiments.METHODS The animal model for colonic stenosis was prepared by partial colonic ligation in eight beagles.The magnetic compression anastomosis of their colonic stricture was performed by endoscopically assisted transanal implantation of the DSAMAR.The anastomotic specimen,obtained 2 wk after the operation,was observed by both the naked eye and a light microscope.RESULTS The DSAMAR was successfully inserted into the proximal end of colon stenosis through the anus.The DSAMAR of seven dogs was successfully transformed into rings,while that of the remaining dog was removed after the first deformation failed.The rings were successfully retransformed after optimization.All animals underwent colonic anastomosis using the DSAMAR.No device-related or procedure-related adverse events were observed.The colostomy specimens of the experimental dogs were obtained 2 wk after the operation.Both gross and histological observations showed good anastomotic healing.CONCLUSION The DSAMAR is a safe and feasible option for the treatment of colon stenosis.Its specific deformation and selfassembly capability maximize the applicability of the minimally invasive treatment.

Effect of Dynamic Pressure Feedback Orifice on Stability of Cartridge-Type Hydraulic Pilot-Operated Relief Valve

Current research on pilot-operated relief valve stability is primarily conducted from the perspective of system dynamics or stability criteria,and most of the existing conclusions focus on the spool shape,damping hole size,and pulsation frequency of the pump.However,the essential factors pertaining to the unstable vibration of relief valves remain ambiguous.In this study,the dynamic behavior of a pilot-operated relief valve is investigated using the frequency-domain method.The result suggests that the dynamic pressure feedback orifice is vital to the dynamic characteristics of the valve.A large orifice has a low flow resistance.In this case,the fluid in the main spring chamber flows freely,which is not conducive to the stability of the relief valve.However,a small orifice may create significant flow resistance,thus restricting fluid flow.In this case,the oil inside the main valve spring chamber is equivalent to a high-stiffness liquid spring.The main mass-spring vibration system has a natural frequency that differs significantly from the operating frequency of the relief valve,which is conducive to the stability of the relief valve.Good agreement is obtained between the theoretical analysis and experiments.The results indicate that designing a dynamic pressure feedback orifice of an appropriate size is beneficial to improving the stability of hydraulic pilot-operated relief valves.In addition,the dynamic pressure feedback orifice reduces the response speed of the relief valve.This study comprehensively considers the stability,rapidity,and immunity of relief valves and expands current investigations into the dynamic characteristics of relief valves from the perspective of classical control theory,thus revealing the importance of different parameters.

Laparoscopic natural orifice specimen extraction-colectomy: A systematic review

Over the last 20 years, laparoscopic colorectal surgery has shown equal efficacy for benign and malignant colorectal diseases when compared to open surgery. However, a laparoscopic approach reduces postoperative morbidity and shortens hospital stay. In the quest to optimize outcomes after laparoscopic colorectal surgery, reduction of access trauma could be a way to improve recovery. To date, one method to reduce access trauma is natural orifice specimen extraction(NOSE). NOSE aims to reduce access trauma in laparoscopic colorectal surgery. The specimen is delivered via a natural orifice and the anastomosis is created intracorporeally. Different methods are used to extract the specimen and to create a bowel anastomosis. Currently, specimens are delivered transcolonically, transrectally, transanally, or transvaginally. Each of these NOSEprocedures raises specific issues with regard to operative technique and application. The presumed benefits of NOSE-procedures are less pain, lower analgesia requirements, faster recovery, shorter hospital stay, better cosmetic results, and lower incisional hernia rates. Avoidance of extraction site laparotomy is the most important characteristic of NOSE. Concerns associated with the NOSE-technique include bacterial contamination of the peritoneal cavity, inflammatory response, and postoperative outcomes, including postoperative pain and the functional and oncologic outcomes. These issues need to be studied in prospective randomized controlled trials. The aim of this systematic review is to describe the role of NOSE in minimally invasive colorectal surgery.

Laparoscopic total mesorectal excision with natural orifice specimen extraction

AIM:To introduce transvaginal or transanal specimen extraction in laparoscopic total mesorectal excision surgery to avoid an abdominal incision. METHODS:Between January 2009 and December 2011,21 patients with rectal cancer underwent laparoscopic radical resection and the specimen was retrieved by two different ways:transvaginal or transanal rectal removal.Transvaginal specimen extraction approach was strictly limited to elderly post-menopausal women who need hysterectomy.Patients aged between 30 and 80 years,with a body mass index of less than 30 kg/m2, underwent elective surgery.The surgical technique and the outcomes related to the specimen extraction,such as duration of surgery,length of hospital stay,and the complications were retrospectively reviewed. RESULTS:Laparoscopic resection using a natural orifice removal approach was successful in all of the 21 patients.Median operating time was 185 min(range,122-260 min)and the estimated blood loss was 48 mL. The mean length of hospital stay was 7.5 d(range,2-11 d).One patient developed postoperative ileus and had an extended hospital stay.The patient complained of minimal pain.There were no postoperative complications or surgery-associated death.The mean size of the lesion was 2.8 cm(range,1.8-6.0 cm),and the mean number of lymph nodes harvested was 18.7(range, 8-27).At a mean follow-up of 20.6 mo(range,10-37 mo),there were no functional disorders associated with the transvaginal and transanal specimen extraction. CONCLUSION:Transvaginal or transanal extraction in L-TME is a safe and effective procedure.Natural orifice specimen extraction can avoid the abdominal wall incision and its potential complications.

Short-term efficacy of natural orifice specimen extraction surgery for low rectal cancer

BACKGROUND This case-control study compared the short-term clinical efficacy of natural orifice specimen extraction surgery(NOSES) using a prolapsing technique and the conventional laparoscopic-assisted approach for low rectal cancer.AIM To further explore the application value of the transanal placement of the anvil and to evaluate the short-term efficacy of NOSES for resecting specimens of low rectal cancer, as well as to provide a theoretical basis for its extensive clinical application.METHODS From June 2015 to June 2018, 108 consecutive laparoscopic-assisted low rectal cancer resections were performed at our center. Among them, 26 specimens were resected transanally using a prolapsing technique(NOSES), and 82 specimens were resected through a conventional abdominal wall small incision(LAP). A propensity score matching method was used to select 26 pairs of matched patients, and their perioperative data were analyzed.RESULTS The baseline data were comparable between the two matched groups. All 52 patients underwent the surgery successfully. The operative time, blood loss,number of harvested lymph nodes, postoperative complication rate,circumferential margin involvement, postoperative follow-up data, and postoperative anal function were not statistically significant. The NOSES group had shorter time to gastrointestinal function recovery(2.6 ± 1.0 d vs 3.4 ± 0.9 d, P= 0.006), shorter postoperative hospital stay(7.1 ± 1.7 d vs 8.3 ± 1.1 d, P = 0.003),lower pain score(day 1: 2.7 ± 1.8 vs 4.6 ± 1.9, day 3: 2.0 ± 1.1 vs 4.1 ± 1.2, day 5: 1.7± 0.9 vs 3.3 ± 1.0, P < 0.001), a lower rate of additional analgesic use(11.5% vs61.5%, P = 0.001), and a higher satisfaction rate in terms of the aesthetic appearance of the abdominal wall after surgery(100% vs 23.1%, P < 0.001).CONCLUSION NOSES for low rectal cancer can achieve satisfactory short-term efficacy and has advantages in reducing postoperative pain, shortening the length of postoperative hospital stay, and improving patients' satisfaction in terms of a more aesthetic appearance of the abdominal wall.

Natural orifice translumenal surgery:Flexible platform review

Natural orifice translumenal surgery(NOTES) has garnished significant attention from surgeons and gastroenterologists,due to the fusion of flexible endoscopy and operative technique.Preliminary efforts suggest that NOTES holds potential for a less invasive approach with certain surgical conditions.Many of the hurdles encountered during the shift from open to laparoscopic surgery are now being revisited in the development of NOTES.Physician directed efforts,coupled with industry support,have brought about several NOTES specific devices and platforms to help address limitations with current instrumentation.This review addresses current flexible platforms and their attributes,advantages,disadvantages and limitations.

EXPERIMENTAL INVESTIGATIONS OF CAVITATION EFFECTS ON FLOW CHARACTERISTICS OF SMALL ORIFICES AND VALVES IN WATER HYDRAULICS

The flow characteristics and cavitation effects of water passing throughsmall sharp-edged cylindrical orifices and valves of different shapes in water hydraulics areinvestigated. The test results using orifices with different aspect ratios and different diametersshow that the flow coefficients in the case of non-cavitating flow are larger than that of flow inthe case of cavitation occurrence. The flow coefficients of flow with cavitation initially decreaseas Reynolds number increases and ultimately tend to be of constant values close to contractioncoefficient. Large aspect ratio has an effect of suppressing cavitation. The experimental resultsabout disc valves illustrate that the valves with sharp edge at large opening are less affected bycavitation than that at small opening. Throttle with triangle notch has better anti-cavitationability than that with square notch. The flowrate of the throttle with square notch is significantlyaffected by the flow direction or the flow passage shape.

A criterion for flow mechanisms through vertical sharp-edged orifice and model for the orifice discharge coefficient

According to the experimental data of the orifice discharge coefficient for the flow through a vertical sharp-edged orifice obtained in the previous study of this work,a theoretical criterion for flow mechanisms of small orifice（viz.thick-walled orifice and nozzle） and large orifice（viz.thin-walled orifice） was proposed based on the ratio of orifice diameter to plate thickness.It can help explain the dissipation of the mechanical energy loss in the flow process for the two flow mechanisms under different operating regimes.The main parameters such as orifice diameter,plate thickness and liquid head were correlated,and a semi-empirical model for orifice coefficient and an empirical model with high precision at the stable region were developed.

Natural orifice surgery applied for colorectal diseases

Clinical natural orifice surgery has been applied to abdominal surgery in recent years,mostly using transvaginal and transgastric access.Rectal and transcolonic natural orifice transluminal endoscopic surgery(NOTES) were tested in animal and cadaver models by a few research groups.Despite the potential advantages of transcolonic NOTES for colorectal diseases,it has not yet been clinically applied.The first successful series of human applications of transcolonic NOTES in the literature from the NOTES Research Group in Brazil provide new possibilities in the field in new transrectal procedures for rectal cancer and benign disease.Successful first human reports on Transcolonic NOTES potentially brings new frontiers and applications for minimally invasive surgery.The treatment of colorectal diseases through flexible Perirectal NOTES Access is a promising new approach alongside existing laparoscopic and open surgery to improve patient care.

Orifice plate cavitation mechanism and its influencing factors

The orifice plate energy dissipater is an economic and highly efficient dissipater. However, there is a risk of cavitaion around the orifice plate flow： In order to provide references for engineering practice, we examined the cavitation mechanism around the orifice plate and its influencing factors by utilizing mathematical analysis methods to analyze the flow conditions around the orifice plate in view of gas bubble dynamics. Through the research presented in this paper, the following can be observed： The critical radius and the critical pressure of the gas nucleus in orifice plate flow increase with its initial state parameter r0 ; the development speed of bubbles stabilizes at a certain value after experiencing a peak value and a small valley value; and the orifice plate cavitation is closely related to the distribution of the gas nucleus in flow. For computing the orifice plate cavitation number, we ought to take into account the effects of pressure fluctuation. The development time of the gas nucleus from the initial radius to the critical radius is about 107-10-5 s; therefore, the gas nucleus has sufficient time to develop into bubbles in the negative half-cycle of flow fluctuation. The orifice critical cavitation number is closely related to the orifice plate size, and especially closely related with the ratio of the orifice plate radius to the tunnel radius. The approximate formula for the critical cavitation number of the square orifice plate that only considers the main influencing factor was obtained by model experiments.