Endoscopic transgastric fenestration versus percutaneous drainage for management of(peri)pancreatic fluid collections adjacent to gastric wall(with video)

BACKGROUND Percutaneous drainage(PCD)and endoscopic approaches have largely replaced surgical drainage as the initial approach for(peri)pancreatic fluid collections(PFC)s,while complications associated with endoscopic stent implantation are common.AIM To introduce a novel endoscopic therapy named endoscopic transgastric fenestration(ETGF),which involves resection of tissue by endoscopic accessory between gastric and PFCs without stent implantation,and to evaluate its efficacy and safety compared with PCD for the management of PFCs adjacent to the gastric wall.METHODS Patients diagnosed with PFCs adjacent to the gastric wall and who subsequently received ETGF or PCD were restrospectively enrolled.Indications for intervention were consistent with related guidelines.We analyzed patients baseline characteristics,technical and clinical success rate,recurrence and reintervention rate,procedure-related complications and adverse events.RESULTS Seventy-two eligible patients were retrospectively identified(ETGF=34,PCD=38)from October 2017 to May 2021.Patients in the ETGF group had a significantly higher clinical success rate than those in the PCD group(97.1 vs 76.3%,P=0.01).There were no statistically significant differences regarding recurrence,reintervention and incidence of complication between the two groups.While long-term catheter drainage was very common in the PCD group.CONCLUSION Compared with PCD,ETGF has a higher clinical success rate in the management of PFCs adjacent to the gastric wall.ETGF is an alternative effective strategy for the treatment of PFCs adjacent to the gastric wall.

Laparoscopic fenestration vs open fenestration in patients with congenital hepatic cysts: A meta-analysis

AIM: To determine whether the outcomes of laparoscopic fenestration (LF) were superior to open fenestration (OF) for congenital liver cysts.METHODS: Comparative studies published between January 1991 and May 2010 on Medline (Ovid),Emsco,PubMed,Science Direct;Cochrane Reviews;CNKI;Chinese Biomedical Database,VIP and other electronic databases were searched.Randomized controlled trials (RCTs) and retrospective case-control studies on the management of congenital hepatic cysts were collected according to the pre-determined eligibility criteria to establish a literature database.Retrieval was ended in May 2010.Meta-analysis was performed using RevMan 5.0 software (Cochrane library).RESULTS: Nine retrospective case-control studies involving 657 patients,comparing LF with OF were included for the final pooled analysis.The meta-analysis results showed less operative time [mean difference (MD): -28.76,95% CI: -31.03 to 26.49,P < 0.00001];shorter hospital stay (MD: -3.35,95% CI: -4.46 to -2.24,P < 0.00001);less intraoperative blood loss (MD: -40.18,95% CI: -52.54 to -27.82,P < 0.00001);earlier return to regular diet (MD: -29.19,95% CI: -30.65 to -27.72,P < 0.00001) and activities after operation (MD: -21.85,95% CI: -31.18 to -12.51,P < 0.0001) in LF group;there was no significant difference between the two groups in postoperative complications (odds ratio: 0.99,95% CI: 0.41 to 2.38,P = 0.98) and cysts recurrence rates.CONCLUSION: The short-term outcomes of LF for patients with congenital hepatic cysts were superior to open approach,but its long-term outcomes should be verified by further RCTs and extended follow-up.

Long-term results of laparoscopic fenestration for patients with congenital liver cysts

BACKGROUND: The feasibility and immediate outcome of laparoscopic fenestration for patients with congenital liver cysts have been generally recognized. The aim of the present study was to assess the long-term results after laparoscopic fenestration. METHODS: A retrospective study was performed on 44 patients with congenital liver cysts who had undergone laparoscopic fenestration between June 1998 and December 2004. Among them, 30 were women and 14 men, aged 57 years on average (range 18-76 years). While 14 patients had solitary cysts, 20 had multiple cysts, and 10 had polycystic liver disease. The results of laparoscopic fenestration, including mortality, morbidity, mean postoperative hospital stay, and recurrences of cysts were evaluated. RESULTS: There was no perioperative death and the morbidity rate was 11% (5/44). All complications were treated conservatively. The mean postoperative hospital stay was 4 days. A mean follow-up of 57 months showed that the rates of cyst recurrence and symptom recurrence were 9% and 4.5%, respectively. CONCLUSION: Laparoscopic fenestration as a feasible and safe treatment procedure for patients with congenital liver cysts can yield very good long-term results.

Effects of Four Types of Pre-swirls on the Leakage, Flow Field, and Fluid-Induced Force of the Rotary Straight-through Labyrinth Gas Seal

The labyrinth seal in turbomachinery is a key element that restricts leakage flow among rotor-stator clearances from high-pressure regions to low-pressure regions. The fluid-induced forces on the rotor from seals during machine operation must be accurately quantified to predict their dynamic behavior effectively. To understand the fluid-induced force characteristics of the labyrinth seal more fully, the effects of four types of pre-swirls on the leakage, flow field, and fluid-induced force of a rotary straight-through labyrinth gas seal (RSTLGS) were numerically investigated using the proposed steady computational fluid dynamics (CFD) method based on the three-dimensional models of the RSTLGS. The leakage, flow field, and fluid-induced force of the RSTLGS for six axial pre-swirl velocities, four radial preswirl angles, four circumferential positive pre-swirl angles, and four circumferential negative pre-swirl angles were computed under the same geometrical parameters and operational conditions. Mesh analysis ensures the accuracy of the present steady CFD method. The numerical results show that the four types of pre-swirls influence the leakage, flow field, and fluid-induced force of the RSTLGS. The axial pre-swirl velocity remarkably inhibits the fluid-induced force, and the circumferential positive pre-swirl angle and circumferential negative pre-swirl angle remarkably promote the fluid-induced force. The effects of the radial pre-swirl angle on the fluid-induced force are complicated, and the pressure forces and viscous forces show the maximum or minimum values at a specific radial pre-swirl angle. The pre-swirl has a negligible impact on the leakage. The four types of pre-swirls affect the leakage, flow field, and fluidinduced force of the RSTLGS to varying degrees. The pre-swirl is the influence factor affecting the leakage, flow field, and fluid-induced force of the RSTLGS. The conclusions will help to understand the fluid-induced force of labyrinth seals more fully, by providing helpful suggestions for engineering practices and a theoretical basis to analyze the fluid–structure interaction of the seal-rotor system in future research.

Advances in research on labyrinth membranous barriers

Integrity of the membranous labyrinth barrier system is of critical importance, which promotes inner ear homeostasis and maintains its features. The membranous labyrinth barrier system is divided into several subsets of barriers which, although independent from each other, are interrelated. The same substance may demonstrate different permeability characteristics through different barriers and under different conditions, while different substances can have different permeability features even in the same barrier under the same condition. All parts of the mem-branous labyrinth barrier structure, including their morphology, enzymes and channel proteins, and theirs permeability characteristics under various physiological and pathological conditions are reviewed in this paper. Infections, noise exposure, ototoxicity may all increase perme-ability of the barriers and lead to disturbances in inner ear homeostasis. Copyright ? 2015 The Authors. Production & hosting by Elsevier (Singapore) Pte Ltd On behalf of PLA General Hospital Department of Otolaryngology Head and Neck Surgery. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Investigation and Improvement of the Staggered Labyrinth Seal

Recent studies on staggered labyrinth seals have focused on the effects of different parameters,such as the pressure ratio and rotational speed on the leakage flow rate.However,few investigations pay sufficient attention to flow details and the sealing mechanism,which would be of practical importance in designing seals having higher performance.This paper establishes a theoretical model to study the seal mechanism,thus revealing that leakage is determined by the pressure ratio and geometric structure.Numerical simulation is implemented to illustrate details of the flow field within the seal structure.Viscous dissipation is used to quantitatively investigate the contribution that each location makes to the seal performance,revealing that orifices and stagnation points are the most important positions in the seal structure,generating the most dissipation.The orifice is carefully studied by using the theoretical model.Experiments for different pressure ratios are conducted and the results match well with those of the theoretical model and numerical simulation,verifying the theoretical model and analysis of the seal mechanism.Three new designs,based on a good understanding of the seal mechanism,are presented,with one reducing leakage by 24.5%.

Treatment of polycystic liver disease with resection-fenestration and a new classification

AIM: To evaluate outcomes in patients with autosomal dominant polycyst liver disease (APLD) treated by combined hepatic resection and fenestration. A new classification was recommended to presume postoperative complications and long outcome of patients. METHODS: Twenty-one patients with APLD were treated by a combined hepatic resection and fenestration technique. All patients were reviewed retrospectively, and clinical symptoms, performance status and morbidity were recorded. A new classifi cation of APLD is recommended here. RESULTS: All patients were discharged when free of symptoms. The mean follow-up time was 55.7 mo and three patients had a recurrence of symptoms at 81, 68 and 43 mo after operation, respectively. The overall morbidity rate was 76.2%. Two patients with Type B-Ⅱ and Type B-Ⅰ developed biliary leakage. Four patients had severe ascites, including three with Type B-Ⅲ and one with Type B-Ⅱ, Nine patients had pleural effusion, including one with Type A-Ⅰ; one with Type B-Ⅰ; fi ve with Type B-Ⅱ; one with Type A-Ⅲ and one with Type B-Ⅲ. Three patients with Type B had recurrence of symptoms, while none with Type A had severe complications. CONCLUSION: Combined hepatic resection and fenestration is an acceptable procedure for treatment of APLD. According to our classifi cation, postoperative complications and long outcome can be predicted before surgery.

Laparoscopic fenestration of multiple giant biliary mucinous cystadenomas of the liver

Biliary cystadenomas of the liver are rare, cystic neoplasms of the biliary ductal system usually occur in middle aged women. We report a case of synchronous multiple huge biliary mucinous cystadenomas with unique features. This is, according to our knowledge, the first report in the literature about three synchronously occurring hepatobiliary cystadenomas. Cystadenomas have a strong tendency to recur, particularly following incomplete excision, and a potential of malignant transformation. A therapeutic re-evaluation may be necessary when the diagnosis of hepatobiliary cystadenoma is made after the operation and an open liver resection should be considered.

ANALYSIS OF COUPLING INFLUENCES OF LABYRINTH SEAL PARAMETERS ON CROSS COUPLED STIFFNESS AND DIRECT DAMPING COEFFICIENT

Labyrinth seal can cause steam-exciting, the structural and operating parameters of labyrinth seal have effect on stability of rotor-system. For investigating the coupling influences of the structure and operating parameters of labyrinth seals on dynamic coefficients, a model of calculating dynamic coefficients of labyrinth seals is presented using a two control volume model. The coupling influences of parameters on cross-coupled stiffness and direct damping of labyrinth seal are discussed. In the conclusion, a reference of preventing steam-exciting vibration and optimum determination of design parameters of labyrinth seals are provided.

Numerical Analysis of Labyrinth Seal Performance for the Impeller Backface Cavity of a Supercritical CO_(2) Radial Inflow Turbine

For a radial inflow turbine(RIT),leakage flow in impeller backface cavity has critical impacts on aerodynamic performance of the RIT and axial force acting on the RIT impeller.In order to control this leakage flow,different types of labyrinth seals are numerically studied in this paper based on a supercritical carbon dioxide(S-CO_(2))RIT.The effects of seal clearance and cavity outlet pressure are first analyzed,and the impacts of seal design parameters,including height,number and shape of seal teeth,are evaluated.Results indicate that adding labyrinth seal can improve cavity pressure and hence adequately inhibits leakage flow.Decreasing the seal clearance and increasing the height of seal teeth are beneficial to improve sealing performance,and the same effect can be obtained by increasing the number of seal teeth.Meanwhile,employing seals can reduce leakage loss and improve RIT efficiency under a specific range of cavity outlet pressure.Finally,the influences of seal types on the flow field in seal cavity are numerically analyzed,and results demonstrate that isosceles trapezoidal type of seal cavity has better sealing performance than triangular,rectangular and right-angled trapezoidal seal cavities.

Labyrinth Seal Design Optimization Based on Quadratic Regression Orthogonal Experiment

The influence of labyrinth seal structure parameters and their interaction on the characteristics of leakage amount are numerically investigated by conducting a quadratic regression orthogonal experiment. To determine the optimal structure parameters of the steam seal for minimizing the leakage amount, a reliable regression equation that does not lack of fit is established. The flow characteristics of the fluid in the labyrinth seal are analyzed in detail. Results show that the leakage amount is greatly influenced by seal cavity depth, convex platform height, seal tooth thickness, and tooth tip clearance, with the tip clearance having the most significant effect. The interaction among the four items exerts a certain impact on the leakage amount. The proposed regression equation exhibits a good significance and does not lack of fit. After optimization, the labyrinth seal demonstrates increased entropy and energy dissipation at the tip of the seal tooth, as well as decreased speed and inertia effect in the cavity, suggesting that the resistance leakage performance of the optimized labyrinth seal is improved.

Effect and sensitivity analysis of the rotational speed on the fluid-induced force characteristics of the straight-through labyrinth gas seal

The effects of the rotational speed on the fluid-induced force characteristics of a straight-through labyrinth gas seal( STLGS) are numerically investigated using the steady computational fluid dynamics( CFD) method based on a three-dimensional model of the STLGS. The fluid-induced force characteristics of the STLGS for five rotational speeds at a pressure drop of △P = 5000 Pa with and without eccentricity are computed. The grid density analysis ensures the accuracy of the present steady-CFD method. The effect and sensitivity analysis show that the changes in rotational speed affect the pressure forces,viscous forces and total pressure distributions on the rotor surface,velocity streamlines,leakage flow rates,and maximum flow velocities. The results indicate that the rotational speed inhibits the pressure forces,leakage flow rates and maximum flow velocities and promotes the viscous forces and total pressure on the rotor surface.

Endoscopic gastric fenestration of debriding pancreatic walled-off necrosis: A pilot study

BACKGROUND Endoscopic drainage of walled-off necrosis(WON) is still a challenge due to stentassociated problems. We explored endoscopic gastric fenestration(EGF) as an innovative alternative intervention.AIM To assess the feasibility, efficacy and safety of EGF for WON.METHODS Between March 2019 and March 2020, five patients with symptomatic WON in close contact with the stomach wall were treated by EGF. Endoscopic ultrasound(EUS) was used to select appropriate sites for gastric fenestration, which then proceeded layer by layer as in endoscopic submucosal dissection. Both the stomach muscularis propria and pseudocyst capsule were penetrated. Fenestrations were expanded up to 1.5-3 cm for drainage or subsequent necrosectomy.RESULTS EGF failed in Case 1 due to nonadherence of WON to the gastric wall. EGF was successfully implemented in the other four cases by further refinement of fenestration site selection according to computed tomography, endoscopy and EUS features. The average procedure time for EGF was 124 min(EUS assessment, 32.3 min;initial fenestration, 28.8 min;expanded fenestration, 33 min), and tended to decrease as experience gradually increased. The diameter of the fenestration site was 1.5-3 cm, beyond the caliber of a lumen-apposing metal stent(LAMS), to ensure effective drainage or subsequent necrosectomy. Fenestration sites showed surprising capacity for postoperative self-healing within 1-3 wk. No EGF-related complications were seen. WON disappeared within 3 wk after EGF. In Case 3, another separate WON, treated by endoscopic LAMS drainage, recurred within 4 d after LAMS removal due to stent-related hemorrhage, and resolved slowly over almost 3 mo. No recurrences were observed in the five patients.CONCLUSION EGF is an innovative and promising alternative intervention for WON adherent to the gastric wall. The challenge resides in the gauging of actual adherence and in selecting appropriate fenestration sites.

Nonlinear dynamic characteristics model of labyrinth seal based on Muszynska model

An accurate seal forces model is the foundation to analyze the rotor-seal systems. In this paper, the Navier-Stokes equation and energy equation are solved to simulate the interior flow field in the labyrinth seal gap. The leakage rate is compared with the experimental results in the literatures. The ：4maximum error is 4% , which proves that the method of employing CFD to simulate the interior flow field of labyrinth seal gap is reliable. Based on this, the interior flow field and fluid exciting force of stage teeth labyrinth seal are studied. By coupling with the Muszynska model, the method of defining the experience loss parameters in Muszynska model is proposed. The results indicate that the experience parameters obtained by the proposed method can depict the nonlinear exciting force of labyrinth seal better.

Labyrinth maze-like long travel-reduction of sulfur and polysulfides in micropores of a spherical honeycomb carbon to greatly confine shuttle effects in lithium-sulfur batteries

Polysulfide absorption in a micropore-rich structure has been reported to be capable of efficiently confining the shuttle effect for high-performance lithium-sulfur(Li–S)batteries.Here,a labyrinth maze-like spherical honeycomb-like carbon with micropore-rich structure was synthesized,which is employed as a template host material of sulfur to study the shuttle effects.The results strongly confirm that a diffusion controlled process rather than an absorption resulted surface-controlled process occurs in an even micropore-rich cathode but still greatly inhibits the shuttle effect.Thus,the battery achieves a high initial discharge specific capacity of 1120 mAh g1 at 0.25 C and super cycling stability for 1635 cycles with only 0.035%capacity decay per cycle with 100%Coulombic efficiency.We would like to propose a new mechanism for shuttle effect inhibition in micropores.In terms of the diffusion control process in microporous paths of a labyrinth maze structure,polysulfides experience a long travel to realize continuous reductions of sulfur and polysulfides until formation of the final solid product.This efficiently prevents the polysulfides escaping to electrolyte.The labyrinth maze-like honeycomb structure also offers fast electron transfer and enhanced mass transport as well as robust mechanical strength retaining intact structure for long cycle life.This work sheds lights on new fundamental insights behind the shuttle effects with universal significance while demonstrating prominent merits of a robust labyrinth maze-like structure in high performance cathode for high-performance Li–S batteries.

Neutron penetration in labyrinths under different beam losses

Multiple analytical methods and Monte Carlo simulations were performed to evaluate neutron penetration in straight and curved labyrinths. Factors studied included variations in beam losses of off-axis point source,on-axis point source,and line source. For the straight labyrinth, it was found that the analytical expressions neglect the dose rate platform appearing at the bend of the labyrinth, and the agreement between analytical methods and Monte Carlo estimation was related to the type of neutron source term. For the curved labyrinth, the neutron attenuation length obtained under different conditions was nearly identical and appeared to be in quite good accord with the empirical formula calculation. Moreover, the neutron energy spectra along the centerline distance of the labyrinth were also analyzed. In the first leg, differences in beam loss led to variance in the distribution of spectra,while in the second and subsequent legs, the spectra were similar, where the main contributors were thermal neutrons. This work is valuable for practical design of the labyrinths in the accelerator facilities.

Labyrinth seal leakage and dynamics characteristics analysis based on Black Model

One of the important problems to be tackled in turbo machines is the leakage dynamics characteristics of labyrinth seals. In this paper we analyzed the effect of labyrinth seal structure and the change in fluid flow pressure on the leakage characteristics of seal. Computational fluid dynamics (CFD) model for 3D labyrinth seal was built which provides a basis for reducing steam flow excitation. The streamline pattern and the pressure drop characteristics for leakage of steam through a labyrinth seal was investigated. Simulations of internal flow and leakage characteristics had been performed by CFD software and Black-Child model. The results showed that the amount of leakage is directly proportional to the tooth gap and inlet pressure and inversely proportional to the cavity depth and outlet pressure. The proposed CFD model provides a feasible method to predict the leakage characteristics of labyrinth seal in response to the structure of seal and the change in inlet-outlet pressures.

Endoscopic Assisted Microscopic Fenestration of Inner Membrane in Cases of Chronic Subdural Hematoma

Introduction: Chronic subdural hematoma (CSDH) is one of the most common types of intracranial hemorrhages and carries a significant morbidity;there is no clear optimal treatment. Recurrence, pneumocephaly and seizures are common complications. We will evaluate outcome after inner membrane fenestration in comparison to burr-hole evacuation only in cases of CSDH. Patients and Methods: Our work was conducted on 20 patients with CSDH from February 2017 to July 2017. Endoscopic-assisted microscopic fenestration technique was used to do inner membrane fenestration in ten patients and the other 10 patients operated upon by traditional burr-hole evacuation. Regular follow up was done up to one month. Results: Clinical outcome was nearly the same in the two groups. Recurrence rate was only noted in the non-fenestration group (20%). Midline shift was better in the membrane fenestration group after one month and we experienced no intraoperative surgical complications related to the fenestration technique. Postoperative complications, such as Pneumocephalus and seizures, were seen in both study groups. Conclusion: Endoscopic assisted microscopic technique decreases surgical risks to do inner membrane fenestration although there is no major difference between doing fenestration or not in clinical outcome, but it may decrease recurrence, but larger studies are needed.

Northern Labyrinth—A Key to Time, Space, Information

Northern labyrinths are stone constructions of different shapes, dating back to III-I century BC. They mainly appear on capes on peninsulas and islands up to 13-25 metresabove the sea level. Their area begins from Scilly Isles (England) and in the White Sea (Russia). Opinions of scientists concerning their designation are controversial. Assumptions about their practical meaning haven’t been proved: no burials have been found underneath;fishing equipment cannot be located so far from the area of tides. Most of the scientists link labyrinths with the sphere of spiritual culture: sanctuaries, altars, sacred places, schemes of rituals and magical centers. Assumptions about calendar designation link the picture of labyrinth with schemes of orbits of the Sun, the Moon, planets and stars. However they do not explain the application of this technology. The author’s concept is based on the opposite astronomical alignment by the shade of gnomon and considers peculiarities of the geographical space of Northern regions (polar days and white nights). The aim of the research is to prove that the key to decoding the picture of a classic Northern labyrinth is a gnomon located in the centre of the construction. Field research has been conducted on Zayztskiy Island in Solovetskiy Archipelago. Experiments of imitation modeling have been done, analysis of linguistic and toponymic materials, archeological, astronomical, ethnographical and mythological and other sources has been implemented. The research has proved that observations of the shade can help to create a calendar in a shape of a bispiral labyrinth. The structure of labyrinth is convenient for defining the North, dividing daytime and defining geographical altitude of the observation point. Orientation in space and time has become the basis for navigation frame of the territory. A set of stone instruments is the key of a navigation frame of the territory. Life-essential stages of the yearly lighting are reflected in specific geometry shapes of shades. They have been preserved in mythological images of the Sun, solar symbols and modern sign systems. Languages, alphabets, numeric systems can be considered as models of geographical space and have evolved thanks to observations of the light movement. Key results of the research: 1) in the past the Sun used to play the leading role in navigation in the North because reference points of the dark sky were not available for observation;2) Northern labyrinths have been created and used thanks to gnomon;3) gnomon has been in the sphere of sacred knowledge for a long time, it was integrated as sundial 2.5 thousand years ago;4) most symbols of the Sun and the Time are connected with gnomon and labyrinth;5) the Sun, observation tools and results of observations are reflected in models of the world around—navigation, linguistic, toponymical, mythological, sacral and semiotic;6) The universal sense of Time helps to understand a wide range of meanings of a sign of a labyrinth: birth;life stages (status, transitions initiations);space time order;reproduction of the benefits, fertility, abundance;knowledge and forecast;management: law and order;eternity-revival;7) Use of solar navigation in formation of information systems is based on steady ratios “natural process—a geometrical sign (the sum of shadows in one day or year)”, universal opportunities of existential parameters for designation of objects, general availability and vital need of this knowledge.

Open Reduction by Fenestration to the Ilium for Central Acetabular Depression Fractures: A Case Report and Operative Technique

Aim: The aim was to report a fenestration technique for gap reduction of acetabular depression fractures. Case presentation: A 76-year-old man suffered from severe left leg pain. The computed tomography scanning showed a displaced acetabular depression fracture, including a third fracture fragment in the center of the acetabular weight-bearing area. We performed a fenestration technique to fenestrate the outer plate of ilium to push down the dislocated fragment of the fracture. The patient was pain-free with good functional outcome of the hip joint at three years after operation. Conclusion: The fenestration technique is useful for displaced acetabular depression fractures. We performed open reduction in this particular case, but the technique may be done less invasively with the use of hip arthroscopy.