Partial Blockage Research Articles

The Continuum of Eustachian Tube Obstruction in Cats: A temporal bone study

The Eustachian tube is a canal from the tympanic cavity to the nasopharynx that is responsible for the aeration, drainage, and pressure equalization of the middle ear. Partial or complete blockage of the tube can trigger severe ear disease. We evaluated pathologic changes from Eustachian tube obstruction (ETO) in 15 temporal bones from cats with bilateral ETO from the temporal bone collection at the University of Minnesota Medical School Otopathology Laboratory. The samples were evaluated for histopathological changes to investigate the continuum of the disease at intervals of 2 days, 1-week, 2-weeks and 4-weeks. Temporal bones were sectioned in the horizontal plane and every 10th section was stained with hematoxylin and eosin. One section from each ear was stained with periodic acid-Schiff and Alcian blue. Sections were studied under light microscopy. The results revealed moderate hyperplasia equally developed throughout the epithelial layer surrounding the middle ear and neutrophil-rich inflammatory cell infiltration. As the duration of obstruction prolonged to the 4th week, compositional change of the middle ear effusion from serous to mucoid that was accompanied with granulation tissue formation was observed. In conclusion, the severity of the findings related to ETO are directly proportional to the duration of the disease. Therefore, patients presenting with long-lasting complaints of ear diseases should be examined for dysfunction or blockage of the Eustachian tube.

Acute effects of intracerebroventricular administration of α-ketoisocaproic acid in young rats on inflammatory parameters.

Maple Syrup Urine Disease (MSUD) is an autosomal recessive inborn error of metabolism (IEM), responsible for the accumulation of the branched-chain amino acids (BCAA) leucine, isoleucine, and valine, in addition to their α-keto acids α-ketoisocaproic acid (KIC), α-keto-β-methylvaleric acid (KMV), and α-ketoisovaleric acid (KIV) in the plasma and urine of patients. This process occurs due to a partial or total blockage of the dehydrogenase enzyme activity of branched-chain α-keto acids. Oxidative stress and inflammation are conditions commonly observed on IEM, and the inflammatory response may play an essential role in the pathophysiology of MSUD. We aimed to investigate the acute effect of intracerebroventricular (ICV) administration of KIC on inflammatory parameters in young Wistar rats. For this, sixteen 30-day-old male Wistar rats receive ICV microinjection with 8 µmol KIC. Sixty minutes later, the animals were euthanized, and the cerebral cortex, hippocampus, and striatum structures were collected to assess the levels of pro-inflammatory cytokines (INF-γ; TNF-α, IL-1β). The acute ICV administration of KIC increased INF-γ levels in the cerebral cortex and reduced the levels of INF-γ and TNF-α in the hippocampus. There was no difference in IL-1β levels. KIC was related to changes in the levels of pro-inflammatory cytokines in the brain of rats. However, the inflammatory mechanisms involved in MSUD are poorly understood. Thus, studies that aim to unravel the neuroinflammation in this pathology are essential to understand the pathophysiology of this IEM.

DETERMINATION OF THE TEMPERATURE FIELD DISTRIBUTION IN THE WINDING RODS OF THE STATOR OF TURBOGENERATORS OF TYPE TVV FOR PURPOSES OF CONTROL AND DIAGNOSTICS

Turbogenerators were and remain the most unreliable element at nuclear power plants in Ukraine. The most dangerous disturbances in the operation of turbogenerators of the TVV type is complete or partial blockage of the hollow conductors of the stator winding. The systems of operational control and technical diagnostics today, in a number of cases, cannot cope with the identification of these phenomena. The complex application of adequate mathematical models, indications of the standard thermal control system and new diagnostic features give the opportunity with sufficient accuracy for practical purposes to detect blockages in the hollow conductors of the stator windings of these turbogenerators. The aim of the work is to develop a program for calculating the three-dimensional temperature field in the rods of the stator winding of a turbogenerator of the TVV-1000-2U3 type, taking into account the temperature field of the stator core, to carry out a test calculation and to compare the experimental and to calculated data. The problem is solved with the help of the finite difference method using the integro-interpolation method.

Effect of binder on CO2, CH4, and N2 adsorption behavior, structural properties, and diffusion coefficients on extruded zeolite 13X

The effect of inorganic binder-based extrusion (Silica sol, Bentonite, Attapulgite, and SB1) in the selective adsorption of CO2, CH4, and N2 on zeolite 13X in the context of flue gas carbon capture and natural gas purification has been studied to reduce CO2 emissions. The effect of extrusion with binders was examined by adding 20 wt% of the mentioned binders to pristine zeolite and the results were analyzed by four approaches; (i) the effect on structural properties was analyzed by XRD patterns followed by Williamson–Hall (W–H) plot, FESEM images, and BET surface area. In addition, the mechanical strength of the shaped zeolites was measured by crush resistance testing; (ii) the effect on the adsorption capacity for CO2, CH4, and N2 were measured by volumetric apparatus up to 100 kPa; (iii) the impact on binary separation (CO2/CH4 and CO2/N2) were investigated; (iv) the influence on diffusion coefficients were estimated by micropore and macropore kinetic model. The results showed that the presence of a binder can cause reductions in BET surface area and pore volume, indicating partial pore blockage. It was found that the Sips model had the best adaptability to the experimental isotherms data. The trend of CO2 adsorption was 13X > pseudo-boehmite > bentonite > attapulgite > silica, in which the adsorption capacity reached 6.02, 5.60, 5.24, 5.00, and 4.71 mmol/g, respectively. Among all samples, silica was found the most suitable binder for CO2 capture in terms of selectivity, mechanical stability, and diffusion coefficients.

Primary Closure vs T-Tube Drainage Following Open Choledochotomy for CBD (Common Bile Duct) Stones.

Choledocholithiasis affects 10%-15% of individuals with gallbladder stones. Approximately 7%-15% of cholecystectomy patients develop common bile duct (CBD) stones. It occurs more frequently in older age groups. It may result in a complete or partial blockage of the bile duct and present as pancreatitis or cholangitis due togallstones. The aim of this study was to compare the outcomes of primary closure of duct and T-tube drainage after open choledochotomy and to evaluate the effectiveness and safety of primary closure. From January 2018 to December 2021, this descriptive study was carried out in the surgical departmentof the Hayatabad Medical Complex in Peshawar. In total, 60 patients who had open choledocholithotomy after a failed endoscopic extraction were included in this study. Of these, 30 (50%) patients got primary duct closure after choledochotomy, while 30 (50%) patients had T-tube insertion. Among the total of 60 patients (primary closure: 30 and T-tube drainage: 30 patients), 10 (16%) were males, while 50 (84%) were female patients. The mean age was recorded as 45.9±13.9, and the mean hospital stay in days in both groups was 4.87±1.4 (T-tube: 5.24±1.50 and primary closure: 4.50±1.3). Complications developed in group A were a biliary leak in three (10%) patients, postoperative jaundice in two (6.5%) patients, wound infection in three (10%), intra-abdominal collection in three (10%) patients, and dislodgement of a tube in two (6.5%), while 17 (57%) patients had no complications developed. If the duct is free of stones, as determined by preoperative choledochoscopy, primary closure of the common bile duct (CBD) is a safe, cost-effective procedure with less morbidity than regular T-tube drainage after open choledochotomy.

Clinical, Endoscopic and Pathological Characteristics of Colorectal Polyps in Children and Adolescents

Background and Aim: Polyps of the gastrointestinal tract (GI) are apparent protrusions from the mucosal surface. The majority of polyps is asymptomatic and goes unnoticed; however in symptomatic situations, the most common clinical manifestations include abdominal discomfort, and rectal prolapse, intestinal blockage, and GI bleeding. The present study intended to assess the colorectal polyps characteristics based on clinical, pathological, and endoscopy in children and adolescents. Patients and Methods: This retrospective study was conducted on 78 children and adolescents (<18 years) with colorectal polyps in Gastroenterology Department of DHQ Teaching Hospital and Mufti Mahmood Memorial Hospital, Dera Ismail Khan from January 2020 to September 2022. Participants were assessed for various clinical variables such as age, gender, colonoscopy-related signs and symptoms, polyp identification, symptom’s onset age, duration between colonic polyp’s endoscopic diagnosis and symptoms onset, and intestinal polyps family history. Polyp’s characteristics involved: frequency, histology, morphological type, and distribution. SPSS version 26 was used for data analysis. Results: The overall mean age was 8.6±2.4 years with an age range 3 to 18 years. Of the total 78 colonic polyps, there were 48 (61.5%) male and 30 (38.5%) females. The most prevalent symptom was rectal bleeding present in 94.6% (n=74) cases with 13.8±16 months. Juvenile was the prevalent polyps found in 76.9% (n=60), out of which 96.7% (n=58) were in left colon. The prevalence of Solitary polyps, multiple polyps, familial adenomatous polyposis, and Peutz-Jeghers syndrome (PJS) was 10.3% (n=8), 6.4% (n=5), 3.8% (n=3), and 2.6% (n=2) respectively. Polyposis syndrome cases were more likely to have old age, diarrhea, anemia, and abdominal pain. Peutz-Jeghers syndrome majority patients experienced intestinal partial blockage with acute episodes, abdominal pain, and emergency laparotomy, resulting in increased morbidity. Conclusion: The present study found that clinical signs of polyposis syndrome include anemia, diarrhea, abdominal pain, polypectomy history, and older age at presentation. Despite the fact that the most commonly diagnosed kind of polyp was juvenile colonic polyps, the current investigation recognized a substantial number of polyposis syndromes children, which are related with individual’s higher rate of morbidity. Keywords: Colonic polyps, Clinical features, Endoscopic characteristics, Colonoscopy

Strategies to enhance the moisture-barrier qualities of concrete mixtures to improve their durability

Moisture transport in concrete significantly impacts its durability attribute, which in turn affects the useful service life of the built concrete infrastructure. A host of physical, chemical, and mechanical deterioration processes of concrete depend on the presence of moisture inside the concrete. Enhancement of the moisture-barrier characteristic of concrete can thus be the key to improving its durability. This paper reports the test results of various strategies implemented to reduce the moisture transport into concrete. These strategies include (i) use of fly ash and silica fume as partial replacement of cement for refinement of capillary porosity, discontinuity of pores, and refinement of the chemistry of hydrated cement matrix; (ii) use of milled waste glass as partial replacement of cement to refine the microstructure of cementitious mixture (iii) use of hydrophobic additives to reduce the affinity of capillary pore surfaces to moisture; and (iv) use of polymer emulsion to line capillary pore surfaces to cause partial blockage of the capillary pore system. Five different concrete mixtures including a control mixture were prepared using the above formulations and tested for moisture sorption, acid attack resistance, abrasion resistance, and compressive strength characteristics at 28 and 90 days of concrete age. Test results indicated enhancement in compressive strength, moisture resistance, and other durability characteristics of the modified mix formulations compared to that of control mixture. Mix formulation incorporating fly ash and silica fume as partial replacement of cement proved to be the most effective combination for achieving the desired improvements in mechanical and durability attributes of concrete. The findings of this study are expected to provide guidelines for designing concrete mixtures with enhanced durability when exposed to aggressive environmental conditions.[copyright information to be updated in production process.]

Clarification of red araçá (Psidium cattleianum Sabine) juice by membrane process: Analysis of permeate flux and loss of bioactive compounds

Red araçá (Psidium cattleianum Sabine) juice was processed using porous membranes to obtain a clarified product with a high amount of phenolic compounds prior to its use as a juice or other beverage. The variations in the permeate flux and concentrations of phenolics were determined in a cross-flow system using a polyetherimide microfiltration membrane (0.44 µm) and polyethersulfone ultrafiltration membrane (50 kDa). Both membranes reduced the initial turbidity (445 ± 2) to almost zero, and resulted in a clear and transparent permeate with a yellow colour. The microfiltration membrane showed better performance with the lowest phenolic compound retention (23.6%) and the highest permeate flux (40.6 ± 2 kg/m2h) in batch mode operation. The permeate flux of the microfiltration system showed an initial sharp decrease followed by a gradual decrease, reaching almost 60% lower than the initial permeate flux. The permeate flux resistance was mainly due to the polarised layer (70.2%), and the predominant fouling mechanism was the partial pore blockage, thus indicating that the solids present in the raw juice had size of the same order as the membrane pores.

Prevention and Management of Intraoperative Pain During Cesarean Section Under Neuraxial Anesthesia: A Technical and Interpersonal Approach

(Anaesthesia. 2022;77:588–597) The term failure in literature has several different meanings including no blockage, partial blockage, or the need for general anesthesia. In an effort to support clinicians and patients during anesthesia, this article outlines eleven recommendations created by the Obstetric Anaesthetists’ Association working group and the Obstetric Anaesthetists' Association Executive Committee that are designed to improve care and provide minimum standards for consent, assessment of pain, management of intraoperative pain, follow-up communication, and communication as a whole. A group of varied anesthetists and a psychologist formed these recommendations based on 44 studies and literature published in Medline, Embase, CINAHL, and PubMed through the years of 1980 and 2020.

Thermal-Hydraulic Analysis of Inward and Outward Fuel Plate Buckling in a Typical MTR Reactor

In the present work, a numerical study of inward and outward buckling of two successive fuel plates of a typical material testing reactor is investigated using computational fluid dynamics code. Fuel plate buckling results in partial blockage of the hot channel. Both buckling toward the inside and outside are considered. Simulations are conducted for different blockage levels of the nominal flow area, i.e., 0%, 20%, 40%, 50%, 60%, and 70% for inward buckling. Blockage levels of 0%, 20%, 40%, 50%, 60%, 70%, 80%, and 90% are considered for outward buckling. The impact of the flow field redistribution in four successive channels on the cooling capacity of each channel is investigated. The obtained results show that for an inward buckling ratio greater than 50%, critical phenomena will occur that could affect the clad integrity. Moreover, for inward buckling of 70%, the maximum clad temperature in the blocked channel reaches the value associated with the onset of nucleate boiling at the operating pressure. On the other hand, for outward buckling of 90%, critical phenomena that could affect the clad integrity will occur.

Large depth to width ratio friction stir welding joint obtained by novel designed tool with double pin

A novel welding tool with a double pin structure was proposed to solve the problem of difficult weld formation with a large depth to width ratio (DWR). Experiments revealed that the novel welding tool could achieve non-defect joints for four common engineering aluminum alloys (2A12-T6/5052-H32/6013-T6/7075-T6), with a DWR of 0.59–0.67. Due to the difference in the direction of material flow between the upper pin and the pin effect, impact slow flow zone was formed in the joint center. The maximum ultimate tensile strength of the 7075-T6 aluminum alloy double pin friction stir welding (DPFSW) joint reached 450.38 MPa, which was 85.8% of the base material. Analysis of the tensile fracture location revealed that the stirring zone of the advancing side and weld nugget zone occurred local blockage, resulting in joint failure. • In this paper, a novel welding tool with a double-pin structure is proposed, and it is demonstrated through experiments that the novel welding tool can achieve defect-free joints with DWR of 0.59–0.67 for four common engineering aluminum alloys. • The DPFSW joint can be divided into seven zones, where the ISFZ is caused by the different flow directions of the upper and lower layers of the DPFSW material, and the interior of this zone consists of a mixture of fine and coarse grains. • The numerical simulation results are consistent with the actual tensile results and the modeling is reasonable. PA and PB are the locations where partial blockage occurs in SZ-AS and UWNZ/DWNZ, which are the weak zones of the joints. • DPFSW joints are greatly influenced by the welding speed. At a welding speed of 100 mm/min, the joint strength was the highest, reaching 450.38 MPa, or 85.8% of BM.

Detection of Partial Blockages in Pressurized Pipes by Transient Tests: A Review of the Physical Experiments

Pressure waves, while traveling along pressurized pipes, collect precious information about possible faults (e.g., leaks and partial blockages). In fact, the characteristics of the pressure wave reflected by the fault are strongly related to it. To encourage the use of the transient test-based technologies (TTBTs) for partial blockage (PB) detection in pressurized pipe systems, it can be of interest to critically analyze the available experimental results and to point out the aspects that need to be investigated in more detail, since no review has been executed so far. Such a deficiency has two negative consequences. The first one is that TTBTs are still relegated to limbo by technicians. The second one is that not enough material is available for refining tools to extract all the information contained in the acquired pressure signals and then to pursue an effective PB detection. As main results of the executed analysis, the following issues can be counted: (i) the lack of tests carried out in large diameter and concrete pipes; (ii) the absence of tests carried out in complex pipe systems (e.g., looped networks); and (iii) the extreme need for considering real pipe systems. The fulfillment of the last issue will greatly contribute to the solutions of the other ones.

A Conditional Generative Adversarial Network for Weather Radar Beam Blockage Correction

Missing or low-quality data regions usually happen to weather radars. One of the most common situations is beam blockage or partial beam blockage. Therefore, correction of weather radar observations that are partially or fully blocked is an indispensable step in radar data quality control and subsequent quantitative applications, especially in complex terrain environments such as the western United States. In this article, we propose a deep learning framework based on generative adversarial networks (GANs) for restoring partial beam blockage regions in polarimetric radar observations using local and global contextual information. Due to the diverse precipitation types, blockage conditions, and ground information in different areas, two radars deployed in two different regions characterized by different precipitation types are used to demonstrate the proposed methodology. Both are S-band operational Weather Surveillance Radar – 1988 Doppler (WSR-88D): KFWS located in Fort Worth, northern Texas, and KDAX located in Davis, northern California. For training the GAN model, this article simulates the partial beam blockage situations by manually cropping observation sectors of both KDAX and KFWS radar data. The trained models were tested using independent precipitation events in Texas and California to demonstrate the model effectiveness in inpainting “missing" data. In addition, this paper cross-tested the data with different precipitation features to examine the generalization capacity of the beam blockage correction models. The beam blockage correction performance is also compared with a traditional linear interpolation approach. The results show that for both domains the continuity of precipitation observations is greatly improved after applying the deep learning-based inpainting approach. For the KFWS test data, some visible discrepancies exist between the results from models trained based on convective and stratiform precipitation events in Texas and California, respectively, yet both models outperform the traditional interpolation method. For the KDAX test data, both the model trained using the KFWS data from convective precipitation events in Texas and the model trained using KDAX data from stratiform precipitation events in California render a similar performance. Although ground truth is not available for the real blocked radar data, the repaired observations demonstrated a great potential for improved quantitative applications.

An Efficient Evolutionary Algorithm for High-Speed Train Rescheduling Under a Partial Station Blockage

An Efficient Evolutionary Algorithm for High-Speed Train Rescheduling Under a Partial Station Blockage

An amplification-free, 16S rRNA test for Neisseria gonorrhoeae in urine.

An amplification-free, nanopore-based nucleic acid detection platform has been demonstrated for rapid, 16S rRNA sequence-specific detection of Neisseria gonorrhoeae at 10-100 CFU mL-1 in human urine against background bacterial flora at 1000 CFU mL-1. Gonorrhea is a very common notifiable communicable disease, antibiotic resistant strains have emerged, and the rate of reported gonococcal infections continues to increase. Since rapid clinical identification of bacterial pathogens in clinical samples is needed to guide proper antibiotic treatment and to control disease spread, it is important to engineer rapid, sensitive, selective, and inexpensive point-of-care (POC) diagnostic devices for pathogens such as N. gonorrhoeae. Our detector technology is based on straightforward conductometric detection of sustained blockage of a glass nanopore. Charge neutral, complementary peptide nucleic acid probes are conjugated to polystyrene beads to capture N. gonorrhoeae 16S rRNA selectively. In the presence of an electric field applied externally through a glass nanopore, the PNA-microbead conjugates that acquire substantial negative charge upon target hybridization are driven to the smaller diameter nanopore. At least partial blockage of the nanopore results in a sustained drop in ionic current that can be measured easily with simple electronics. The ability to detect N. gonorrhoeae over the range of 10 to 100 CFU mL-1 spiked in human urine was demonstrated successfully with estimated sensitivity and specificity of ∼98% and ∼100%, respectively. No false positives were observed for the control group of representative background flora (E. coli, K. pneumoniae, and E. faecalis) at 1000 CFU mL-1. Also, N. gonorrhoeae at 50 CFU mL-1 was successfully detected against 1000 CFU mL-1 of background flora in urine. These results suggest that this amplification-free technology may serve as the basis for rapid, inexpensive, low-power detection of pathogens in clinical samples at the POC.

Large eddy simulations of turbulent heat transfer in packed bed energy storage systems

The present paper aims to study the effect of partial blocking and flow regime on the mutual turbulent interplay between porous and non-porous regions in packed bed energy storage systems (PBESSs). To this end, high-fidelity pore-scale large eddy simulations (LES) are conducted for two PBESS configurations, namely full blockage and partial blockage under the discharge process at three Re numbers 3600, 7200, and 14,400. The influences of the flow major features, including flow channelling and leakage, on the rate of heat transfer (Nusselt number) and pressure drop are investigated for various flow Reynolds (Re) numbers. Results demonstrate that the channelling effect inside the porous region strongly affects the temperature profiles and leads to local maximum peaks of Nusselt (Nu) number on the upper and lower sides of pore elements. For the partial blockage, it is observed that 79 % of the flow entering the porous block leaks from the porous region into the non-porous region through the porous-fluid interface at Re = 3600, which reduces by 26 % as the Re increases to 14,400. The flow leakage leads to the formation of counter-rotating vortex pair structures inside and over the porous block. It also causes local maximum peaks of Nu number at the lower sides of pore elements and changes the stagnation points' position at the leading edge of the porous block near the porous-fluid interface. Compared to the full blockage configuration, temperature profiles inside the porous block are less dependent on the Re number for the partial blockage case. Finally, the pressure drag force for the full blockage is about 21.4 and 30.9 times that of partial blockage at Re = 3600 and 14,400, respectively. Whereas at these Re numbers, the average Nu number for the full blockage is nearly 51.2 % and 57.3 % higher than that of the partial blockage. Consequently, blocking the entire fluid flow area may not necessarily be the best design, since it may result in excessive pressure drops without significant heat transfer enhancement.

Simulation of the effect of partial and total blockage of a sub-channel on two-phase flow through a 5 x 5 square rod bundle

The study of the effect of blockage on two-phase flow parameters in rod bundles is of significance to the prediction of the thermal-hydraulic behavior of fuel assembly under hypothetical accident conditions. The two-phase flow computational fluid dynamics method was used to simulate the fluid flow in 5 × 5 under partial (75%) and total blockage of a sub-channel. A scenario with no blockage was considered a baseline for further analysis into subsequent cases with blockages. The effect of the blockage on the pressure drop, void fraction, subchannel average velocities, and the turbulence intensity between the sub-channels were analyzed at different hydraulic diameters before and after the blockage, and compared. The 75% partial blockage of a single sub-channel increased the average pressure drop between 1Dh and 5Dh downstream by 0.47 kPa compared to the baseline scenario. Bubbles coalesce at the vicinity of the blockage. The effect of the blockage on other flow parameters extends to 46 Dh downstream of the blockages. The effect of these different blockage conditions can provide a reference for the parameter setting of the sub-channel analysis codes.

Selective hydrodeoxygenation of lignin-derived phenols to alkyl cyclohexanols over highly dispersed RuFe bimetallic catalysts

Selective hydrodeoxygenation (HDO) of phenolic compounds derived from the pyrolysis lignin-oil to desired products is a promising route in the high-value utilization of biomass-derived products. Cyclohexanol, as one of the important chemical materials, is an intermediate of catalytic HDO of guaiacol. Controllable selective HDO is conducted to improve the cyclohexanol selectivity over RuFe bimetallic catalyst prepared by ethylene glycol reduction method in this work. 99.99% guaiacol conversion and 81.35% cyclohexanol selectivity are obtained over optimized 2Ru2.5Fe/Al2O3-EG catalyst, which is better than those over 2Ru/Al2O3-EG catalyst. The mild catalyst preparation method gives it a high dispersion and uniform distribution of Ru and Fe species on the support. Various characterizations have proved that the intimate contact between Ru and Fe2O3 species contributes to the improvement of cyclohexanol selectivity. Partial blockage of Ru sites by Fe2O3 species slightly reduces the hydrogen adsorption capacity while the addition of Fe helps enhancing the hydrogenolysis of C-OMe bond. The reciprocal effect facilitates the removal of methoxyl groups and hinders the dehydroxylation of cyclohexanol to cyclohexane. Besides, other phenolic compounds and pyrolysis lignin-oil as substrates also show good selective HDO reactivity to corresponding alkyl cyclohexanols, implying potential application in the transformation from lignin-oil to high-value products.

Study on the influence of flow blockage in severe accident scenario of CAP1400 reactor

Deformed fuel rods can cause a partial blockage of the flow area in a subchannel. Such flow blockage will influence the core coolant flow and further the core heat transfer during the reflooding phase and subsequent severe accidents. Nevertheless, most of the system analysis codes simulate the accident process based on the assumed flow blockage ratio, resulting in inconsistencies between simulated results and actual conditions. This paper aims to study the influence of flow blockage in severe accident scenario of the CAP1400 reactor. First, the flow blockage model of ISAA code is improved based on the FRTMB module. Then, the ISAA-FRTMB coupling system is adopted to model and calculate the QUENCH-LOCA-0 experiment. The correctness and validity of the flow blockage model are verified by comparing the peak cladding temperature. Finally, the DVI Line-SBLOCA accident is induced to analyze the influence of flow blockage on subsequent CAP1400 reactor core heat transfer and core degradation. From the results of the DVI Line-SBLOCA accident analysis, it can be concluded that the blockage ratio is in the range of 40%–60%, and the position of severe blockage is the same as that of cladding rupture. The blockage reduces the circulation area of the core coolant, which in turn impacts the heat exchange between the core and the coolant, leading to the early failure and collapse of some core assemblies and accelerating the core degradation process.

Occlusion of Two Coronary Arteries Simultaneously

A 60-year-old woman with a history of stroke and known hypertension presented to the emergency room after experiencing acute chest pain for an hour. Her blood pressure was 80/55 mmHg, and her pulse rate was 42 beats per minute. An electrocardiogram (ECG) showed first-degree cardiac block and inferior and anteroseptal leads with acute ST-elevation myocardial infarction (STEMI) (Panel A). The patient was promptly moved to the catheterization lab after receiving first care. Early distal left anterior descending (LAD) artery partial blockage with thrombus-containing lesion was found during diagnostic coronary angiography (Panel B). After a challenging engagement of the right coronary artery (RCA), it was discovered that there was a proximal complete blockage with a thrombus-containing lesion (Panel C). Unfortunately, the patient collapsed with severe bradycardia (34 beats per minute) and hypotension (systolic blood pressure = 60 mmHg), which did not react to quick intravenous fluid and atropine ampules. A temporary pacemaker was soon implanted. After the pacing was started, the patient developed ventricular fibrillation, which required cardiopulmonary resuscitation (CPR) and successive DC shocks before the pulse returned to sinus. The RCA was successfully stented quickly, followed by the stenting of the LAD lesion (Panel D and E). The patient rapidly returns to sinus rhythm with great coronary blood flow, and normal blood pressure is recorded after one hour of recovery. Two hours later, echocardiography demonstrated normal systolic function with no aberrant segmental motion. Occlusion of two coronary arteries is a critical disorder that requires immediate detection and treatment to avoid complications such as ventricular arrhythmias and cardiogenic shock. The patient was released with excellent outcomes.