Sealed System Research Articles

Design of spinning disk atomization equipment for synthesis of drug-loaded microparticles.

The synthesis of drug-loaded microparticles with precise control over size distribution and shape is crucial for achieving desired drug distribution in microparticles and tuning drug release profiles. Common large-scale production techniques produce microparticles with a broad particle size distribution and require challenging operating conditions. Recent methods employing microfluidics have enabled the production of microparticles with a uniform size distribution. Still, these methods are limited to low and moderate production rates and can handle fluids with a limited range of physicochemical properties. In this study, we couple the spinning disk atomization (SDA) technique for microdroplet production with a precipitation method to generate drug-loaded polymeric microparticles with a narrow size distribution. The design criteria and fabrication of equipment with a non-contact seal system that integrates spinning disk atomization and precipitation methods for conducting laboratory experiments involving volatile hydrocarbons while ensuring operational and personnel safety are discussed. The production of itraconazole drug-loaded microparticles using the SDA setup that considers the system's operation, maintenance, and safety aspects are discussed, and the system's efficiency is evaluated through material balance. This laboratory equipment is capable of producing drug-loaded microparticles with a narrow size distribution under moderate operating conditions and can be scaled up suitably to meet high production requirements. The applications of this equipment can be explored in various fields, such as the production of drug particles, conversion of waste polymers into microparticles, and microencapsulation of food ingredients.

Multi-signal logic-gate sensing platform based on CoOOH nanoflakes for quantitative point-of-care detection of prostate specific antigen

Herein, we propose a cobalt oxyhydroxide (CoOOH) nanoflake-mediated multi-signal sensing system for the immediate detection of biomarkers. The platform employs monoclonal antibody Ab1-modified magnetic nanoparticles (CuFe2O4-Ab1) as the capture target and multiwalled carbon nanotubes (MWCNTs) modified with polyclonal antibody Ab2 and nicotinamide adenine dinucleotide (NADH) as the signal probe (Ab2-MWCNTs-APBA-NADH). By taking the prostate-specific antigen (PSA) as a target, the feasibility of the sensing platform was confirmed. When exposed to PSA, the sandwich immune complex (CuFe2O4-Ab1/PSA/Ab2-MWCNTs-APBA-NADH) was formed by antigen–antibody specific recognition. Thereafter, the NADH of the signal probe inhibited the peroxidase-like activity of the CoOOH nanosheets, leading to decreased pressure, weight and temperature responses in the sealed system, in line with the “INHIBIT” logic gate. The three responses had a strong linear relationship with PSA concentration, with relative standard deviations (RSD) of 0.1–1.5%. With simple procedures and straightforward readout strategies, the proposed method can be easily generalized for specific detection of other analytes by changing the antibodies.

The role of TiO2:SnO2 heterojunction for partial oxidation of methane by photoelectrocatalytic process at room temperature

Partial Oxidation of Methane into hydrocarbons using photoelectrochemical routes is attractive from a sustainability point of view owing to the possibility of using renewable energy (i.e., solar illumination) to activate this stable molecule. However, the process demands the development of novel catalysts that can promote methane activation and oxidation in a controlled manner to increase energy conversion efficiency. Herein, we demonstrated that semiconductor heterostructures improved charge separation compared to the individual materials alone. A more effortless transfer between bands favors the separation of the electron-hole (e−/h+) pairs generated by the photoelectrocatalytic system and prevents them from recombining. This process produces reactive oxygens, essential to driving methane oxidation conversion of the C–H bond cleavage. TiO2:SnO2 semiconductor heterojunction catalysts in film shape were investigated for methane oxidation via a photoelectrocatalytic process. The methane oxidation reactions were carried out in an inflow and sealed electrochemical system for 1 h. Liquid-state nuclear magnetic resonance revealed methanol and acetic acid as the main liquid products, where the TiO2:SnO2 heterojunction exhibited better performance with values of 30 and 8 µmol.cm−2.h−1, respectively. Compared to their materials alone, the superior performance of the TiO2:SnO2 heterojunction is attributed to the formation of heterostructure type II that enables a more effortless transfer between bands, facilitating the separation of the generated e−/h+ pairs under UV-Vis irradiation. The outcomes achieved here will motivate further studies for developing semiconductor heterojunction structure catalysts in photoelectrocatalysis to partially oxidize methane into valuable chemicals.

Test rig for submerged transmissions in wave energy converters as a development tool for dynamic sealing systems

A submerged transmission, fitted with a dynamic sealing system, in a wave energy converter (WEC) serves the purpose of transmitting the force, absorbed by a wave activated body, to an encapsulated power take-off (PTO) system, while preventing seawater from entering the capsule. Dry generator operation is generally a prerequisite for attaining long technical service life. Little attention seems to be devoted in publications to the study of dynamic sealing systems in WECs, and to test rigs for experimental verification and/or evaluation of the ability/performance of existing dynamic sealing systems in a controlled laboratory environment. This paper begins by presenting some of our earlier research within the focus area of dynamic sealing systems, incl. design considerations and typical operating conditions. This part also presents the 1st laboratory test rig, used for verifying the sealing ability of the piston rod mechanical lead-through design in the 1st and 2nd full-scale experimental WEC prototype from Uppsala University. In 2021 project DynSSWE (Dynamic Sealing Systems for Wave Energy) was initiated. Drawing from experience, the project includes development of a new test rig, representing a tool for further development of dynamic sealing systems. This paper introduces steps in the design and development process of that new test rig, enabling accelerated long-term test runs with a setup of multiple piston rod specimens. The test specimens’ will be surface treated differently with the aim of improving the prospects of a long maintenance free service life. Since the new test rig is in the design stage, seal testing results are not yet reported. The presented work is funded by the Swedish energy agency with the aim of improving subsystem performance in wave energy devices.

Dry suction water seal system for management of pericardial fluid during epicardial ablation.

Epicardial ablation is an important approach in the management of patients with complex ventricular arrhythmias. Irrigated ablation catheters present a challenge in this potential space due to fluid accumulation that can cause hemodynamic compromise, requiring frequent manual fluid aspiration. In this series, we report our initial experience with the use of a dry suction water seal system for pericardial fluid management during epicardial ablation. Consecutive patients undergoing epicardial ventricular tachycardia (VT) ablation at a single center were included. All patients underwent epicardial access via a subxiphoid approach with a single operator. A deflectable sheath was advanced into the pericardial space, and the side port was attached to a dry suction water seal system attached to wall suction at -20 mmHg. Procedural information including patient characteristics, outcomes, and adverse events. After a period of initial experience, pericardial fluid infusion and aspiration volumes were recorded. Eleven patients were included in this series. All patients underwent epicardial ablation with complete success achieved in 8 of the 11 patients and partial success in the remaining patients. Pericardial fluid intake ranging from 485 to 3050 mL with aspiration of 350-3050 mL using the dry suction water seal system. No adverse events occurred. Dry suction water seal drainage systems can provide a safe strategy for efficient pericardial fluid management during epicardial VT ablation, potentially shortening procedure duration.

The effect of seasonal variation of medium viscosity on centrifugal desanding in shaft seal water system of suction dredger: Numerical simulation and mechanism study

As a lubrication medium, the shaft-seal water often carries substantial sand particles in the cutter suction dredger, causing severe wear and tear of the internal components of the slurry pump. It has been proved that the shaft seal water system could be optimized by introducing a hydro cyclone to prolong the service life of the slurry pump. However, it was found that the seasonal variation of water viscosity would produce an obvious effect on the centrifugal separation of sand particles. Therefore, in this study, the influence of seasonal viscosity change on the flow field characteristics and sand particle separation was systematically studied by computational fluid dynamics (CFD). The simulation results showed that the fluid and pressure field in hydro cyclone has good symmetry under different viscosity. While with the increase of viscosity, the fluid resistance coefficient increases, resulting in a downward trend of turbulent kinetic energy and an upward trend of negative pressure zone, which is not conducive to sand particle separation. Moreover, to verify the consistency between simulation and actual industry, the grade efficiency of sand particles was studied and discussed. The average particle size of sand could be reduced from 37.8 μm to 8.1 μm, and the separation efficiency could reach 90% under better suitable dredging conditions (Salinity: 34%, Temperature: 20 °C). Further, the experimental and industrial results showed that the fish hook effect inevitably existed in practice due to the entrainment of coarse particles. This study would provide theoretical support for the subsequent optimization of the shaft seal water system.

Muzzle flow field characteristics of underwater sealed launch system under different projectile shapes

The underwater sealed launch is one of effective launch technologies for enhancing the velocity of underwater vehicle and also for achieving better interior ballistic performance. However, the underwater muzzle flow field based on this sealed technology is a major consideration as it decides initial kinetic stability and subsequent shooting accuracy. Hence, this study establishes a comprehensive model involving in a modified sealed interior ballistic model, muzzle multiphase turbulent flow model and supercavitation model due to high-velocity moving vehicle, and mainly investigates the effect of the vehicle shapes on the underwater sealed muzzle field. An experiment for the muzzle field of underwater sealed launch is also carried out using a 12.7 mm-caliber launch device and water tank. Comparisons on flow patterns of muzzle field and expansion displacements of Taylor cavity on computational results are done with experimental studies, and a reasonable match has been obtained in these comparisons. The results show that the gas sealed in the launch barrel firstly injects into the water forming an initial Taylor cavity once the sealed device is broken. Then, the propellant combustion-gas just with high pressure and high temperature injects into the water with the moving vehicle. Consequently, a complicated interaction effect between these two types of gases and high-density water takes place, generating complicated shock wave phenomena in the muzzle field. Different vehicle shapes can affect the formation of the shock waves and expansion characteristics of Taylor cavity in the water. Eventually, the diameter of the Mach disk is always the largest for the cylindrical underwater vehicle and the axial pressure fluctuation for the vehicle with a cavitator are most significant with a lowest temperature field due to strong gas-liquid interaction.

Drying of Spent Nuclear Fuel: Considerations and Examples

A recently revised American Society for Testing and Materials consensus standard guide for drying of spent nuclear fuel (SNF) provides considerations and guidance for preparing SNF for its safe storage in a sealed dry storage system. The standard discusses (1) needs for drying, (2) techniques to dry, and (3) demonstration of adequate dryness. No specific approach is prescribed since the effective techniques and needs for drying depend on the specifics of the fuel and dry storage system. This paper discusses these topics using examples for both Zr-alloy-clad commercial SNF and for aluminum-alloy-clad research reactor SNF. Residual water can include free water (liquid and/or vapor), physisorbed water bound to internal surfaces, and chemisorbed water incorporated into surface films, such as (oxy)hydroxides. The potential impacts of these residual waters are corrosion/oxidation, radiolytic breakdown into gaseous and/or reactive species, and canister pressurization. For commercial SNF, inadvertent free water, even up to large amounts (e.g., 10+ mol), is not predicted to cause adverse corrosion degradation, except possible fuel oxidation for breached SNF. For aluminum-clad SNF, the production of radiolytic hydrogen with contribution from the chemisorbed water in its hydrated oxides is a primary consideration. For both SNF systems, canister pressurization is predicted to be well within the canister design, and flammability would not pose a safety concern using an oxygen limit of 5 vol % criterion. (Flammability control can be achieved by limiting either hydrogen or oxygen, and an oxygen limit is expected to be easier to meet in the presence of radiolytic H2 generation.) The two primary technologies for SNF drying, vacuum drying and forced-gas dehydration, are described herein, and drying tests and campaigns using these methods are cited. Dryness criteria and the methods used to detect and measure residual (free) water are also discussed.

A control method of excess material in cold plate processing with a runner

Cooling plates are widely used in modern electronic equipment and usually contain channels with a complex structure. Welding, heat treatment, machining, and turnover on cooling plates are often accompanied by waste such as mental swarf. The waste could enter the plates and block the liquid inlets or outlets, thereby affecting the normal operation of electronic equipment. In light of this, we design a labyrinth seal system for heat treatment and a sealing block for mechanical processing with proper techniques. The research results show that waste can be prevented from entering the channel and help keep the entire cooling system clean.

Stability Analysis of Hydrodynamic Mechanical Seals in Multifrequency Excitation

The dynamic characteristics of the complex relationship among the sealing system, excitation, and response have a considerable impact on the operational reliability of hydrodynamic mechanical seals, which is a critical issue in the field of sealing theory and technology. Scholars at home and abroad have established dynamic models and calculated the displacement responses of dynamic and static rings in the time domain based on the force on these rings so that the response results can be used for system stability analysis. Neither are the excitation characteristics of cavitation load extracted, nor are the distance response and system leakage rate of the dynamic and static rings analyzed under coupled cavitation and random excitation. In this study, under different operating conditions of the hydrodynamic mechanical seal system, the liquid film evaporation load and seismic load are applied to study the frequency domain response of the distance between the dynamic and static rings and the system leakage rate. The following conclusions have been obtained: Assuming that the chamber pressure is 0.5 MPa and the spring specific pressure is 0.055 MPa, during stable operation, the distance between the moving and stationary rings at 1500 rpm~3000 rpm speeds is 1.12 μm~3.05 μm. For a specific spring pressure of 0.055 MPa, medium pressures of 0.2 MPa~1.0 MPa, and spindle speeds of 1500 rpm~3000 rpm, the excitation force is 30 N, and the frequency is 30 Hz, And the seismic load is assumed to be sinusoidal, the excitation force is 6 N, the fundamental frequency is 120 Hz, and the system leak rate is in 0.1 mL/min~1.3 mL/min. Under multi-frequency excitation coupling, the distance between the dynamic and static rings will decrease as the pressure of the medium in the sealing cavity increases, and this will increase with the increase in the rotating speed. The leakage rate of the system will increase with the increase in the rotating speed and the pressure of the medium, and the test value is largely consistent with the theoretical value.

Lung viral infection modelling in a bioengineered whole-organ

Lung infections are one of the leading causes of death worldwide, and this situation has been exacerbated by the emergence of COVID-19. Pre-clinical modelling of viral infections has relied on cell cultures that lack 3D structure and the context of lung extracellular matrices. Here, we propose a bioreactor-based, whole-organ lung model of viral infection. The bioreactor takes advantage of an automated system to achieve efficient decellularization of a whole rat lung, and recellularization of the scaffold using primary human bronchial cells. Automatization allowed for the dynamic culture of airway epithelial cells in a breathing-mimicking setup that led to an even distribution of lung epithelial cells throughout the distal regions. In the sealed bioreactor system, we demonstrate proof-of-concept for viral infection within the epithelialized lung by infecting primary human airway epithelial cells and subsequently injecting neutrophils. Moreover, to assess the possibility of drug screening in this model, we demonstrate the efficacy of the broad-spectrum antiviral remdesivir. This whole-organ scale lung infection model represents a step towards modelling viral infection of human cells in a 3D context, providing a powerful tool to investigate the mechanisms of the early stages of pathogenic infections and the development of effective treatment strategies for respiratory diseases.

Evaluation of Electrocardiogram-Gated Computed Tomography Angiography to Quantify Changes in Geometry and Dynamic Behavior during the Cardiac Cycle of the Nellix Endovascular Sealing System.

The Nellix endovascular sealing system (EVAS) was a unique concept with regard to its sealing concept that failed, related to high migration rates. We investigated the changes in aortoiliac morphology during the cardiac cycle before and after EVAS using electrocardiography (ECG)-gated CT. Eight patients scheduled for EVAS were prospectively enrolled. ECG-gated CT scans were made pre- and postoperatively. Measurements were performed in the mid-systolic and mid-diastolic phases. Endpoints were changes in infrarenal aortoiliac morphology postoperatively compared to preoperatively and their changes in the cardiac cycle. Both pre- and postoperatively, there were no changes during the cardiac cycle. EVAS caused an increase in neck diameter and surface in both phases (p < 0.001). EVAS increased the luminal AAA volume (p < 0.001), with a decrease in thrombus volume (p < 0.001) in both phases and an increase in total volume (p < 0.001) in the systolic phase. During follow-up, one patient presented with >5 mm migration. There were no differences in the movements of this patient compared to the remaining patients. The cardiac cycle had a very limited effect on the aortoiliac dynamics before and after EVAS and, therefore, there is probably not a role for ECG-gated CT in enhanced surveillance programs. EVAS itself has a significant impact on anatomy, particularly the neck diameter, length, and volumes of the AAA.

Application of Load-Sharing Concept to Mechanical Seals

Mechanical seals are mechanisms that are used to prevent fluid leakage. Since the seal surfaces are in contact with one another, hydrodynamic and contact forces are functions of surface roughness. Additionally, since the lubrication regime under specific operating conditions such as low speed or high load causes the seal to operate in the mixed lubrication regime, thus the contact of asperities plays an important role. The primary purpose of this paper is to apply the load-sharing concept to study the behavior of a mechanical seal in a mixed lubrication regime. The predicted results are compared to the published data from the literature, showing acceptable accuracy. The model presented in this paper can predict the performance of the mechanical seal system in a short execution time while providing acceptable accuracy by considering the surface roughness effect.

Coupled Hydromechanical Modelling of a Vertical Hydraulic Sealing System Based on the Sandwich Principle

For the shaft sealing of a repository for radioactive waste, a Sandwich sealing system was developed by KIT-CMM consisting of bentonite-based sealing segments (DS) and sand mixture-based equipotential segments (ES). To demonstrate the functionality of the Sandwich sealing system, various laboratory tests (MiniSandwich tests and semi-technical scale experiments) have been carried out before a large-scale experiment has been implemented in situ at the Mont Terri Rock Laboratory (CH). An important coupled process in the Sandwich system is the swelling deformation of the DS while aqueous fluid penetrates into the system. Consequently, the interparticle porosity (effective porosity) of the DS decreases by swelling strain, resulting in a reduction in the permeability of the DS. Pore space of the ES also decreases slightly due to swelling stress in the adjacent DS, which also leads to a reduction in the permeability of the ES. To understand the coupled hydromechanical processes of the Sandwich sealing system, a numerical model was developed to interpret the experimental observations from the MiniSandwich tests and to parameterize different components. A linear swelling model for DS and empirical functions for the swelling deformation-induced permeability change for both DS and ES segments were introduced into the coupled model with Richards’ flow and elastic model. Sensitivity analysis with parameter variations of the most important parameters reduces the uncertainty in the system behavior.

Na2Mg2P2O7F2: A new diphosphate of the cuspidine family without disorder designed by targeted structural modulation

A new alkali/alkali-earth metal pyrophosphate fluoride Na2Mg2P2O7F2 without the structural disorder in the cuspidine family has been successfully prepared in the sealed system. Na2Mg2P2O7F2 crystallizes in the space group P21/c (No. 14) of the monoclinic crystal system. The structure of Na2Mg2P2O7F2 is shown to be an intricate three-dimensional (3D) framework that consists of the 2D layers [Mg4O12F2]∞ and the 1D chain [Na2O8F3]∞ interlinked by isolated P2O7 groups, which demonstrates the precise coordination environment of cations and the framework in inorganic alkali/alkaline earth metal pyrophosphate fluoride. By comparing with other phosphate structures, we found that the introduction of F is conducive to the consistent arrangement of anionic group P2O7 and enriches the diversity of cationic polyhedra. In addition, first-principle theoretical studies were also carried out to aid the understanding of microstructures, and Na2Mg2P2O7F2 possesses a large band gap (7.1 eV) and has potential applications in the deep ultraviolet region.

Quantifying the impact of heat in support seal configuration for aero engines

AbstractLeakage, deformations, power loss, heat generation in the support seal system and other issues are typical when support seals are developed. The design of the support seal system has progressively evolved over recent decades as part of an ongoing effort to provide effective cooling for the aero engine secondary air system. In particular, oil heat management in the oil chamber has strict requirements, which limit the heat generation of the support seal system. The potential of supporting seal research with an oil system is investigated in this work. The combination of the CFD/FEA method and quantifying the heat generation entering the oil chamber allows for improvements not just to the individual buffer air seal unit, but the oil seal together. The analysis relies on the combination of quantifying heat generation entering the oil chamber to provide a mutual influence of neighbouring labyrinth seals. The mutual influence requires further analysis, considering the thermal deformation of the rotor/stator to provide further accurate geometry parameters in preliminary seal designs. The experimental test was conducted to verify the preliminary CFD-FEA loosely coupled analysis result, which reveals that in a turbine support seal system, the radius of the buffer air seal has a significant influence on the leakage flow rate and power loss of the oil seal, which should take into account the integral influence of the pressure difference of the oil seal caused by the radius change of the buffer air seal and the running clearance of the oil seal.

Explanation of the mechanisms of unsteady gas flow through the turbocharger seal system, including thermal and structural interactions

Gas flow in the seal system can be expected during the operation of a turbocharger and is associated with negative effects on the quality of the lubricant or turbocharger efficiency. Gas flow also affects particulate matter production due to lubricant entrainment in the compressor or turbine. The prediction of gas flow rates depends on many design parameters and the operating conditions of the turbocharger, but sufficiently accurate descriptions of the gas flow mechanisms and their quantification depending on the operating conditions have not yet been presented. The proposed computational approach simultaneously solves the gas dynamics in the seal system, the heat transfer in the turbocharger rotor-bearing system and the dynamics of the seal rings and rotor, including the bearings. The computational model for the turbocharger of a heavy-duty vehicle engine is experimentally validated. Two mechanisms have major influences on gas mass flow: the gas flow through the thin gap between the moving ring and groove and the flow through the ring gap. The results show that the importance of these mechanisms depends on several geometrical dimensions of the seal system and the operating conditions of the turbocharger, with a strong connection to the rotor dynamics and thermal load of the impellers. Influences involving rotor movement or rotor thermal conditions are crucial, and their non-inclusion limits the ability to correctly predict gas mass flow.

Mechanisms of Chemical and Autogenous Shrinkage in Alkali-Activated Hybrid Systems

This study aimed to investigate the role of chemical and autogenous shrinkage as well as microstructure of a hybrid system composed of alkali-activated ash blended with portland cement. Three alkali-activated binders were produced with 30% portland cement and different types of ash (70% of bottom ash, 70% of rice husk ash, or 35% of each type of ash). Chemical shrinkage was measured by the buoyancy method. The microstructural and surface analysis were investigated by scanning electron microscopy (SEM), nitrogen adsorption-desorption isotherms, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analyses. Autogenous shrinkage, rather than chemical shrinkage, was mainly responsible for the shrinkage observed in these sealed systems. The results showed that the main mechanism involved in the shrinkage of this hybrid system is associated with the microstructural reorganization of the aluminosilicates phases resulting from polymerization.

Dynamic Analysis and Independent High-Order Nonlinear Dynamics of a Rotor-Bearing-Finger Seal System

Finger seals are widely investigated because of their excellent sealing performance. The finger beam can deform to adapt to the rotor radial vibration when working. The seal is in contact with the rotor surface. Such nonlinear contact forces induce instability and high-order independent nonlinear vibrations, which are harmful to the rotor system. Previous research has usually focused on the finger itself, while the impact of a particular finger end, called the foot, has not drawn much attention. In this paper, a nonlinear finger seal force model considering the interaction between the feet of adjacent laminates is established. It is characterized by coupling rotor displacement and seal deformation and agrees well with the finite element simulation. Based on the Timoshenko beam theory and short bearing assumption, a rotor-bearing-finger seal system is established. The nonlinear dynamic characteristics of the system are analyzed through spectrum cascades, bifurcation diagrams, Poincaré maps, etc. The effects of rotational speed, eccentricity, pressure difference, and the number of seal laminates are studied. The period doubling evolution of the nonlinear vibrations is discussed. High-order independent nonlinear vibrations are discovered, and their detailed nonlinear mechanisms are revealed. This research provides a theoretical basis for the rotor-bearing-finger seal system.

A STUDY ON INTERCOSTAL CHEST TUBE IN PATIENTS WITH PNEUMOTHORAX IN A TERTIARY CARE CENTRE: A RETROSPECTIVE STUDY

Background : Pneumothorax is the accumulation of air within the pleural space, i.e within two layers of the pleura. It may occur spontaneously due to underlying lung pathology or due to trauma in various forms. Spontaneous pneumothorax is further classied into primary and secondary depending on the etiological ndings. Intercostals water sealed drainage system, commonly known as chest tube, are designed to remove air or uid from the pleural cavity which accumulates due to various etiologies and has been used for the management of pneumothorax for a long time. This is a retrospective observational study made on 50 p Methods : atients who presented with pneumothorax due to various causes and were managed by chest tube drainage in a tertiary care hospital. Results and observations : Of 50 patients, 46 patients (92%) had successful outcome. However the p-value came out to be 0.64 (&gt; 0.05), hence the role of chest tube in primary management of pneumothorax is ruled out. The initial management of pneumothorax is conservative with observatio Conclusion : n and needle aspiration. Chest tube drainage should be considered only when conservative measures fail and clinical and radiological parameters suggest deterioration, since the more invasive method as primary treatment causes more complications