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As an important control element in steam heating piping systems, the safety and stability of inverted bucket steam valves determine the reliable operation of the system. Therefore, it is necessary to investigate the acoustic mechanism of inverted bucket steam valves. Aiming at the difficulty of numerical simulation in accurately predicting the aerodynamic noise of inverted bucket steam valves, this paper proposes a new method for simulating the aerodynamic noise of inverted bucket steam valves based on multiband analysis (LES). The flow field of the inverted bucket steam valve is numerically simulated using the LES method to obtain wall pressure pulsation information and fluid velocity pulsation information, which are used as excitation sources for acoustic simulation. The characteristics of dipole and quadrupole sound sources were obtained by applying the FW-H method and experimentally verified. The results show that a new multifrequency band analysis method for inverted bucket steam valves is effective by comparing the numerical simulation results, in which the dipole source dominates in the low-frequency band, in the medium frequency range, the quadrupole source outperforms the dipole source, but in the high frequency range, the quadrupole source is dominant. The experimental results are in good agreement with the simulation results, and the correctness of the numerical simulation is confirmed by the fact that there is less than a 3% difference between the findings of the numerical simulation and the experimental data. [ABSTRACT FROM AUTHOR]

Purpose: In the modern era of robotic renal procedures and diagnostics, an even more detailed anatomical understanding than hitherto is necessary. Valves of the renal veins (RVV) have been underemphasized and have been disputed by some authors, and few textbooks describe them. The current anatomical study was performed to address such shortcomings in the literature. Methods: One hundred renal veins were studied in fifty adult formalin-fixed cadavers. Renal veins were removed from the abdomen after sectioning them flush with their entrance to the renal hilum. The inferior vena cava was then incised longitudinally and opened, and RVV were examined grossly and histologically. A classification scheme was developed and applied to our findings. Results: Nineteen RVVs were observed in the fifty cadavers (38%). Four (8%) valves were found on right sides and fifteen (30%) on left sides. The valves were seen as cord/band-like, folds, and single and double leaflets. Histologically, they were all extensions of the tunica intima. Conclusion: On the basis of our study, RVV are not uncommon. They were more common on left sides, and on both sides, they were found within approximately one centimeter of the junction of the inferior vena cava and renal vein. Although the function of such valves cannot be inferred from this anatomical study, the structures of the Single leaflet valve (TS2) and Double leaflet valve (TS3) valves suggest they could prevent venous reflux from the IVC into the kidney. [ABSTRACT FROM AUTHOR]

Purpose: Extremely premature neonates diagnosed with post-haemorrhagic hydrocephalus (PHH) are recognised to have particularly poor outcomes. This study assessed the impact of a number of variables on outcomes in this cohort, in particular the choice of shunt valve mechanism. Methods: Electronic case notes were retrospectively reviewed of all premature neonates admitted to our centre for management of hydrocephalus between 2012 and 2021. Data included (i) gestational age, (ii) birth weight, (iii) hydrocephalus aetiology, (iv) surgical intervention, (v) shunt system, (vi) 'surgical burden' and (vii) wound failure and infection rate. Data was handled in Microsoft Excel and statistical analysis performed in SPSS v27.0 Results: N = 53 premature hydrocephalic patients were identified (n = 28 (52.8%) female). Median gestational age at birth was 27 weeks (range: 23–36 + 6 weeks), with n = 35 extremely preterm patients and median birth weight of 1.9 kg (range: 0.8–3.6 kg). Total n = 99 programmable valves were implanted (n = 28 (28.3%) de novo, n = 71 (71.2%) revisions); n = 28 (28.3%) underwent n ≥ 1 pressure alterations, after which n = 21 (75%) patients had symptoms improve. In n = 8 patients exchanged from fixed to programmable valves, a mean reduction of 1.9 revisions per patient after exchange was observed (95%CI: 0.36–3.39, p = 0.02). Mean overall shunt survival was 39.5 weeks (95%CI: 30.6–48.5); 33.2 weeks (95%CI: 25.2–41.1) in programmable valves and 35.1 weeks (95%CI: 19.5–50.6) in fixed pressure (p = 0.22) with 12-month survival rates of 25.7% and 24.7%, respectively (p = 0.22). Shorter de novo shunt survival was associated with higher operation count overall (Pearson's R: − 0.54, 95%CI: − 0.72 to − 0.29, p < 0.01). Wound failure, gestational age and birth weight were significantly associated with shorter de novo shunt survival in a Cox regression proportional hazards model; gestational age had the greatest impact on shunt survival (Exp(B): 0.71, 95%CI: 0.63–0.81, p < 0.01). Conclusion: Hydrocephalus is especially challenging in extreme prematurity, with a shorter de novo shunt survival associated with higher number of future revisions. Programmable valves provide flexibility with regard to pressure setting, with the potential for fewer shunt revisions in this complex cohort. [ABSTRACT FROM AUTHOR]

This study introduces an application of innovative medical technology, Photon Counting Computer Tomography (PC CT) with novel detectors, for the assessment of shunt valves. PC CT technology offers enhanced visualization capabilities, especially for small structures, and opens up new possibilities for detailed three-dimensional imaging. Shunt valves are implanted under the skin and redirect excess cerebrospinal fluid, for example, to the abdominal cavity through a catheter. They play a vital role in regulating cerebrospinal fluid drainage in various pathologies, which can lead to hydrocephalus. Accurate imaging of shunt valves is essential to assess the rate of drainage, as their precise adjustment is a requirement for optimal patient care. This study focused on two adjustable shunt valves, the proGAV 2.0® and M. blue® (manufactured by Miethke, Potsdam, Germany). A comprehensive comparative analysis of PC CT and traditional X-ray techniques was conducted to explore this cutting-edge technology and it demonstrated that routine PC CT can efficiently assess shunt valves' adjustments. This technology shows promise in enhancing the accurate management of shunt valves used in settings where head scans are already frequently required, such as in the treatment of hydrocephalus. [ABSTRACT FROM AUTHOR]

Background: Early extubation (EEx) is defined as the removal of the endotracheal tube within 8 h postoperatively. The present study involved determining the availability and threshold of the vasoactive-inotropic score (VIS) for predicting EEx in adults after elective rheumatic heart valve surgery. Methods: The present study was designed as a single-center retrospective cohort study which was conducted with adults who underwent elective rheumatic heart valve surgery with CPB. The highest VIS in the immediate postoperative period was used in the present study. The primary outcome, the availability of VIS for EEx prediction and the optimal threshold value were determined using ROC curve analysis. The gray zone analysis of the VIS was performed by setting the false negative or positive rate R = 0.05, and the perioperative risk factors for prolonged EEx were identified by multivariate logistic analysis. The postoperative complications and outcomes were compared between different VIS groups. Results: Among the 409 patients initially screened, 379 patients were ultimately included in the study. The incidence of EEx was determined to be 112/379 (29.6%). The VIS had a good predictive value for EEx (AUC = 0.864, 95% CI: [0.828, 0.900], P < 0.001). The optimal VIS threshold for EEx prediction was 16.5, with a sensitivity of 71.54% (65.85–76.61%) and a specificity of 88.39% (81.15–93.09%). The upper and lower limits of the gray zone for the VIS were determined as (12, 17.2). The multivariate logistic analysis identified age (OR, 1.060; 95% CI: 1.017–1.106; P = 0.006), EF% (OR, 0.798; 95% CI: 0.742–0.859; P < 0.001), GFR (OR, 0.933; 95% CI: 0.906–0.961; P < 0.001), multiple valves surgery (OR, 4.587; 95% CI: 1.398–15.056; P = 0.012), and VIS > 16.5 (OR, 12.331; 95% CI: 5.015–30.318; P < 0.001) as the independent risk factors for the prolongation of EEx. The VIS ≤ 16.5 group presented a greater success rate for EEx, a shorter invasive ventilation support duration, and a lower incidence of complications than did the VIS > 16.5 group, while the incidence of reintubation was similar between the two groups. Conclusion: In adults, after elective rheumatic heart valve surgery, the highest VIS in the immediate postoperative period was a good predictive value for EEx, with a threshold of 16.5. [ABSTRACT FROM AUTHOR]

Three‐dimensional paper‐based microfluidic devices have shown great potential in various applications, including point‐of‐care diagnostics, environmental monitoring, and tissue engineering. However, their fabrication is still limited to stacking and origami methods. Inspired by the art of bamboo braiding in China, we developed a novel fabrication technique based on the braiding concept to create three‐dimensional paper‐based microfluidic devices with PDMS‐impregnated paper substrate as the building units. The resulting three‐dimensional paper device brings unique advantages, including compactness, facile disassembly, and real‐time flow visualization. The multiplexed glucose analysis with a braided device integrated with 16‐switchable valves for flow control was further fabricated to demonstrate the device's applicability. We envision braiding‐based fabrication technology opening new possibilities and bringing broad applications for three‐dimensional paper microfluidic devices. [ABSTRACT FROM AUTHOR]

The cavitation erosion failure of pumps or valves induces the low efficiency and reduced service life of nuclear reactors. This paper reviews works regarding the cavitation erosion of pumps and valves in the nuclear power industry and academic research field. The cavitation erosion mechanisms of materials of pumps and valves are related to the microstructure and mechanical properties of the surface layer. The cavitation erosion resistance of austenitic stainless steel can be ten times higher than that of ferritic steel. The cavitation erosion of materials is related to the hardness, toughness, and martensitic transformation capacity. Erosion wear and erosion–corrosion research is also reviewed. Erosion wear is mainly influenced by the hardness of the material surface. Erosion–corrosion behavior is closely connected with the element composition. Measures for improving the cavitation erosion of pumps and valves are summarized in this paper. The cavitation erosion resistance of metallic materials can be enhanced by adding elements and coatings. Adhesion, inclusion content, and residual stress impact the cavitation erosion of materials with coatings. [ABSTRACT FROM AUTHOR]

Purpose: The main function of the turbine inlet valve (TIV) in a hydroelectric power plant is to prevent flow of water to the turbine whenever the turbine is not operating. Usually, the valve responsible for this operation is spherical with annular seals to perform the sealing function. Occasionally, when the valve is set into a closed orientation, the annular seal may not execute its sealing function properly though develop periodic oscillations accompanied by periodic leakage flows. These seal vibrations cause pressure fluctuations in the penstock pipeline, which risks the plant's reliable and safe operation. Therefore, the primary goal of this research is to present a simplified theoretical model, able to clarify the excitation mechanism of the periodic seal vibration and simulate the plant's transient behavior. Afterwards, develop some recommendations to enhance the stable operation of the (TIV). Methods: The system governing equations comprises the water hammer equations to model the water flow through the various pipelines, the vibrating seal equation of motion, and the system boundary conditions. Results: The dynamic instability of the (TIV) vibrations is more likely to arise at higher input reservoir energy levels and at the first harmonic of the seal oscillation. In addition, modifying the (TIV) by increasing pilot pipeline head losses and reducing its diameter can eliminate the (TIV) vibrations and warrant the plant's safe operation. Conclusion: Results revealed that fluid compressibility and acoustic transmission have a decisive effect on the fluid-dynamic forces acting on the seal and the (TIV) stability. In addition, the origin of the (TIV) vibrations is the valve leakage flow through the service seal. [ABSTRACT FROM AUTHOR]

Microneedle has made excellent contribution in the era of biomedical sector. This paper presents a reservoir-based out-of-plane silicon carbide (SiC) microneedle which has two lumens for delivering drug. The total height of the designed microneedle is 451 µm where the conical tip area is about 69.39 µm2. The additional part of this microneedle is a reservoir which is trapezium in shape having a height of 150 µm. This work use COMSOL Multiphysics software for the structural analysis and Ansys Workbench software to investigate the fluid analysis. The flow analyses are performed by releasing drugs from the reservoir where different viscosity based sample drugs are included. Although reservoir-based microneedles are existing, however, there is no system to control the fluid in those microneedles. Thus, this work proposes a controllable microneedle which able to control the drug flow by using a valve. For both the case of valveless and with a valve, the drug velocities are determined. As paracetamol has highest viscosity among other drugs, it provides lowest velocities. Conversely, the flow of aspirin shows high velocity of 6.51E-2 m/s without a valve and 4.26E-2 m/s with a valve. To analyze the skin insertion performance, a skin model including six layers is designed. The simulation results ensure that the proposed microneedle can penetrate the human skin successfully with less stress and deformation. [ABSTRACT FROM AUTHOR]

Studies showed that integrating coating or valve into Peripherally Inserted Central (PICC) can prevent related complications. However, data regarding efficiency were controversial. Therefore, a systematic review was needed to analyse the effect of PICC materials and designs on reduction of PICC‐related complications. We searched PubMed, Cochrane library, EMbase, grey literature and referent literature from inception to 5 August 2022. Randomized controlled trials (RCTs) and case–control study were included. Two authors extracted data independently, using a predesigned Excel form, and assessed the quality of included RCTs according to the Cochrane Handbook for Systematic Reviews (V5.1.0), case–control study was assessed by the Newcastle‐Ottawa Scale. Data were analysed using Review Manager (v5.3.0). A total of 10 RCTs and one case–control study were included. Meta‐analysis results showed that PICC designs reduce the incidence of obstruction, and at the critical value of PICC‐associated bloodstream infection, but may have no effects on other complications. Based on the literature reviewed, we can only say PICC new materials did not reflect significant reduction on complications, what's more, the result needs more multicentre, large RCTs to support. We suggested clinicians combine descriptive research and cost‐effect analysis to select appropriate PICC materials and designs for patients. [ABSTRACT FROM AUTHOR]

This study introduces an application of innovative medical technology, Photon Counting Computer Tomography (PC CT) with novel detectors, for the assessment of shunt valves. PC CT technology offers enhanced visualization capabilities, especially for small structures, and opens up new possibilities for detailed three-dimensional imaging. Shunt valves are implanted under the skin and redirect excess cerebrospinal fluid, for example, to the abdominal cavity through a catheter. They play a vital role in regulating cerebrospinal fluid drainage in various pathologies, which can lead to hydrocephalus. Accurate imaging of shunt valves is essential to assess the rate of drainage, as their precise adjustment is a requirement for optimal patient care. This study focused on two adjustable shunt valves, the proGAV 2.0® and M. blue® (manufactured by Miethke, Potsdam, Germany). A comprehensive comparative analysis of PC CT and traditional X-ray techniques was conducted to explore this cutting-edge technology and it demonstrated that routine PC CT can efficiently assess shunt valves’ adjustments. This technology shows promise in enhancing the accurate management of shunt valves used in settings where head scans are already frequently required, such as in the treatment of hydrocephalus.

Abstract Background Early extubation (EEx) is defined as the removal of the endotracheal tube within 8 h postoperatively. The present study involved determining the availability and threshold of the vasoactive-inotropic score (VIS) for predicting EEx in adults after elective rheumatic heart valve surgery. Methods The present study was designed as a single-center retrospective cohort study which was conducted with adults who underwent elective rheumatic heart valve surgery with CPB. The highest VIS in the immediate postoperative period was used in the present study. The primary outcome, the availability of VIS for EEx prediction and the optimal threshold value were determined using ROC curve analysis. The gray zone analysis of the VIS was performed by setting the false negative or positive rate R = 0.05, and the perioperative risk factors for prolonged EEx were identified by multivariate logistic analysis. The postoperative complications and outcomes were compared between different VIS groups. Results Among the 409 patients initially screened, 379 patients were ultimately included in the study. The incidence of EEx was determined to be 112/379 (29.6%). The VIS had a good predictive value for EEx (AUC = 0.864, 95% CI: [0.828, 0.900], P 16.5 (OR, 12.331; 95% CI: 5.015–30.318; P 16.5 group, while the incidence of reintubation was similar between the two groups. Conclusion In adults, after elective rheumatic heart valve surgery, the highest VIS in the immediate postoperative period was a good predictive value for EEx, with a threshold of 16.5.

During the production and operation of some bulk handling facilities, nuclear material deposits remaining after cleaning in and about process equipment, interconnecting piping, filters and adjacent work area or equipment, which is called holdup. In order to meet the requirements of nuclear material accounting management, the physical inventory of nuclear materials shall be carried out according to the specified frequency, and the amount of nuclear materials shall be the measured value. Quantitative measurement of holdup in equipment is one of the technical difficulties in nuclear material measurement for nuclear facilities. Holdup measurement is important for radiation protection, critical safety and nuclear material management. The valve is a key component to control the material transfer in the process of nuclear material production. The valve is welded to pipe, which is not conducive to sampling. In this paper, mass of uranium in the valve was measured by γ-ray spectroscopy. It is necessary to study absolute detection efficiencies of the detector for known source distribution. Firstly, the passive efficiency calibration was selected to simulate the absolute detection efficiencies. Analysis models consist of detector model and valve models, they were placed under the same observation system by the transforming coordinate method. Analysis models of detector and valves were built based on information of the detector and design drawing of the valves. Two point sources, 57Co and 137Cs, were used to verify the model. Under the combination of different crystal radius and length parameters, the absolute detection efficiencies for full-energy γ-rays peak were simulated. The crystal parameters of the LaBr3 detector were adjusted. The root mean square of the relative deviation between the simulation results and the experimental results was calculated. The crystal parameters with the smallest root mean square are the best parameters. The relative deviation between the experimental results and Monte Carlo simulation results for point sources is within 5%. The standard uranium sample was used to carry out experiments. The count rate of characteristic γ-ray was measured by the LaBr3 detector. The absolute detection efficiencies were simulated by the analysis model. The holdup was calculated according to the relationship between count rate of characteristic γ-ray and the mass of uranium. The results show that the relative deviation between the measured results and the reference values of uranium mass is within 15%. The feasibility of the method for measuring the uranium holdup in the valves is preliminarily confirmed by the experiments. The transforming coordinate, a simple and easy solution, by which the analysis model can be quickly and accurately built.

As an important control element in steam heating piping systems, the safety and stability of inverted bucket steam valves determine the reliable operation of the system. Therefore, it is necessary to investigate the acoustic mechanism of inverted bucket steam valves. Aiming at the difficulty of numerical simulation in accurately predicting the aerodynamic noise of inverted bucket steam valves, this paper proposes a new method for simulating the aerodynamic noise of inverted bucket steam valves based on multiband analysis (LES). The flow field of the inverted bucket steam valve is numerically simulated using the LES method to obtain wall pressure pulsation information and fluid velocity pulsation information, which are used as excitation sources for acoustic simulation. The characteristics of dipole and quadrupole sound sources were obtained by applying the FW-H method and experimentally verified. The results show that a new multifrequency band analysis method for inverted bucket steam valves is effective by comparing the numerical simulation results, in which the dipole source dominates in the low-frequency band, in the medium frequency range, the quadrupole source outperforms the dipole source, but in the high frequency range, the quadrupole source is dominant. The experimental results are in good agreement with the simulation results, and the correctness of the numerical simulation is confirmed by the fact that there is less than a 3% difference between the findings of the numerical simulation and the experimental data.

Industrial process plants use emergency shutdown valves (ESDVs) as safety barriers to protect against hazardous events, bringing the plant to a safe state when potential danger is detected. These ESDVs are used extensively in offshore oil and gas processing plants and have been mandated in the design of such systems from national and international standards and legislation. This paper has used actual ESDV operating data from four mid/late life oil and gas production platforms in the North Sea to research operational relationships that are of interest to those responsible for the technical management and operation of ESDVs. The first of the two relationships is between the closure time (CT) of the ESDV and the time it remains in the open position, prior to the close command. It has been hypothesised that the CT of the ESDV is affected by the length of time that it has been open prior to being closed (Time since the last stroke). In addition to the general analysis of the data series, two sub-categories were created to further investigate this possible relationship for CT and these are “above mean” and “below mean”. The correlations (Pearson's based) resulting from this analysis are in the “weak” and “very weak” categories. The second relationship investigated was the effect of very frequent closures to assess if this improves the CT. ESDV operational records for six subjects were analysed to find closures that occurred within a 24 h period of each other. However, no discriminating trend was apparent where CT was impacted positively or negatively by the frequent closure group. It was concluded that the variance of ESDV closure time cannot be influenced by the technical management of the ESDV in terms of scheduling the operation of the ESDV.

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Infective endocarditis (IE) is characterized by high morbidity and mortality rates, despite recent improvements in diagnostics and treatment. We aimed to investigate incidence, clinical characteristics, and in-hospital mortality in a large-scale nationwide cohort. Methods: Using data from the German Federal Bureau of Statistics, all IE cases in Germany between 2007 and 2019 were analyzed. Logistic regression models were fitted to assess associations between clinical factors and in-hospital mortality. Results: In total, 86,469 patients were hospitalized with IE between 2007 and 2019. The mean age was 66.5 ± 14.7 years and 31.8% (n = 27,534/86,469) were female. Cardiovascular (CV) comorbidities were common. The incidence of IE in the German population increased from 6.3/100,000 to 10.2/100,000 between 2007 and 2019. Staphylococcus (n = 17,673/86,469; 20.4%) and streptococcus (n = 17,618/86,469; 20.4%) were the most common IE-causing bacteria. The prevalence of staphylococcus gradually increased over time, whereas blood culture-negative IE (BCNIE) cases decreased. In-hospital mortality in patients with IE was 14.9%. Compared to BCNIE, staphylococcus and Gram-negative pathogens were associated with higher in-hospital mortality. In multivariable analysis, factors associated with higher likelihood of in-hospital mortality were advanced age, female sex, CV comorbidities (e.g., heart failure, COPD, diabetes, stroke), need for dialysis or invasive ventilation, and sepsis. Conclusions: In this contemporary cohort, incidence of IE increased over time and in-hospital mortality remained high (~ 15%). While staphylococcus and streptococcus were the predominant microorganisms, bacteremia with staphylococcus and Gram-negative pathogens were associated with higher likelihood of in-hospital mortality. Our results highlight the need for new preventive strategies and interventions in patients with IE. [ABSTRACT FROM AUTHOR]

Neo-aortic root dilatation can lead to significant late morbidity after the arterial switch operation (ASO) for dextro-transposition of the great arteries (d-TGA). We sought to examine the growth of the neo-aortic root in d-TGA. A single-center, retrospective cohort study of patients who underwent the ASO between July 1, 1981 and September 30, 2022 was performed. Morphology was categorized as dextro-transposition of the great arteries with intact ventricular septum (d-TGA-IVS), dextro-transposition of the great arteries with ventricular septal defect (d-TGA-VSD), and double-outlet right ventricle-transposition of the great arteries type (DORV-TGA). Echocardiographically determined diameters and derived z scores were measured at the annulus, sinus of Valsalva, and sinotubular junction immediately before the ASO and throughout follow-up. Trends in root dimensions over time were assessed using linear mixed-effects models. The association between intrinsic morphology and the composite of moderate-severe aortic regurgitation (AR) and neo-aortic valve or root intervention was evaluated with univariable and multivariable Cox proportional hazards models. Of 1,359 patients who underwent the ASO, 593 (44%), 666 (49%), and 100 (7%) patients had d-TGA-IVS, d-TGA-VSD, and DORV-TGA, respectively. Each patient underwent a median of 5 echocardiograms (Q1-Q3: 3-10 echocardiograms) over a median follow-up of 8.6 years (range: 0.1-39.3 years). At 30 years, patients with DORV-TGA demonstrated greater annular (P < 0.001), sinus of Valsalva (P = 0.039), and sinotubular junction (P = 0.041) dilatation relative to patients with d-TGA-IVS. On multivariable analysis, intrinsic anatomy, older age at ASO, at least mild AR at baseline, and high-risk root dilatation were associated with moderate-severe AR and neo-aortic valve or root intervention at late follow-up (all P < 0.05). Longitudinal surveillance of the neo-aortic root is warranted long after the ASO. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, a novel flow control strategy which is the inlet throttled pump was used to design an angular velocity control system for rotary actuator. Inlet throttled systems have good performance in addition to their high efficiency compared to traditional valve-controlled systems. The flow in the proposed system is adjusted by a valve that is positioned at the pump inlet with the purpose of reducing the energy loses across the valve. This regulated flow is used then to control the actuator angular velocity. The system was modeled and the open loop stability and performance were studied. In order to improve the system performance, proportional-integralderivative (PID) and H-infinity controllers have been designed. The multiplicative uncertainty was analyzed to assess the robustness of the feedback control system where six parameters were considered uncertain within a range of +10%. The robust stability and performance requirements of the closed-loop angular velocity control system were assessed in the frequency domain. The time response of the system showed that the system is stable with both PID and H-infinity controllers. The PID controller have the advantages of simplicity and high response speed while the H8 controller provides better nominal performance, robustness, and stability. The H8 controller can handle parametric uncertainty without requiring pure integral term which is a significant advantage over the PID controller. On the other hand, the PID controller falls short of achieving robust performance, making it less suitable for systems that require high levels of performance and robustness. In summary, the H8 controller is a more comprehensive solution for ensuring the best performance of a system. In contrast, the PID controller may be more suitable for systems with less stringent performance requirements. [ABSTRACT FROM AUTHOR]

The paper shows that mechanical vibrations occur in a wide frequency range in the hydraulic systems operating in the real world. Hydraulic valves are also exposed to these vibrations. The paper gives examples of vibration sources and suggests that the influence of vibrations on hydraulic valves could be reduced. Particular attention was paid to the vibrating proportional distributor. The amplitude-frequency spectrum of pressure pulsation in a hydraulic system with a vibrating proportional distributor was analysed. During the tests, the frequency of external mechanical vibrations acting on the proportional distributor and their direction was changed. [ABSTRACT FROM AUTHOR]

Copyright of Control Theory & Applications / Kongzhi Lilun Yu Yinyong is the property of Editorial Department of Control Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this article, the computer assisted design, flow simulation, optimization of production parameters and unique design prototype manufacturing of a check valve with 16 bar pressure, 5 m/s flow rate and 52000 m³/h flow coefficients, which have never been achieved before in the valve sector, were presented to the attention of the readers. Check valves have a critical role that do not allow reverse flow of the fluid passing through them and are generally designed to secure the pipeline. A small mistake in design may cause great damage in the system. For this reason, a new product of which the disc material exposed to 5 m/s fluid velocity, the body subjected to 16 bar pressure and the system with a flow coefficient of 52000 m³/h were designed by the SolidWorks, the flow was simulated with CFD (Computational Fluid Dynamics), and the mechanical resistance was analysed by FEA (Finite Element Analysis). Fluent, CFD and mechanical modules of ANSYS were used to define the parameters of the design. The manufactures of the products designed in the computer environment have been produced by casting method with a 45% ferritic microstructure and impact resistance twice as high as the standard requirements have been implemented. [ABSTRACT FROM AUTHOR]

Industrial process plants use emergency shutdown valves (ESDVs) as safety barriers to protect against hazardous events, bringing the plant to a safe state when potential danger is detected. These ESDVs are used extensively in offshore oil and gas processing plants and have been mandated in the design of such systems from national and international standards and legislation. This paper has used actual ESDV operating data from four mid/late life oil and gas production platforms in the North Sea to research operational relationships that are of interest to those responsible for the technical management and operation of ESDVs. The first of the two relationships is between the closure time (CT) of the ESDV and the time it remains in the open position, prior to the close command. It has been hypothesised that the CT of the ESDV is affected by the length of time that it has been open prior to being closed (Time since the last stroke). In addition to the general analysis of the data series, two sub-categories were created to further investigate this possible relationship for CT and these are "above mean" and "below mean". The correlations (Pearson's based) resulting from this analysis are in the "weak" and "very weak" categories. The second relationship investigated was the effect of very frequent closures to assess if this improves the CT. ESDV operational records for six subjects were analysed to find closures that occurred within a 24 h period of each other. However, no discriminating trend was apparent where CT was impacted positively or negatively by the frequent closure group. It was concluded that the variance of ESDV closure time cannot be influenced by the technical management of the ESDV in terms of scheduling the operation of the ESDV. [ABSTRACT FROM AUTHOR]

Magnetorheological (MR) fluids have been known to react to magnetic fields of sufficient magnitudes. While in the presence of the field, the material develops a yield stress. The tunable property has made it attractive in, e.g., semi-active damper applications in the vibration control domain in particular. Within the context of a given application, MR fluids can be exploited in at least one of the fundamental operating modes (flow, shear, squeeze, or gradient pinch mode) of which the gradient pinch mode has been the least explored. Contrary to the other operating modes, the MR fluid volume in the flow channel is exposed to a non-uniform magnetic field in such a way that a Venturi-like contraction is developed in a flow channel solely by means of a solidified material in the regions near the walls rather than the mechanically driven changes in the channel's geometry. The pinch-mode rheology of the material has made it a potential candidate for developing a new category of MR valves. By convention, a pinch-mode valve features a single flow channel with poles over which a non-uniform magnetic field is induced. In this study, the authors examine ways of extending the dynamic range of pinch-mode valves by employing a number of such arrangements (stages) in series. To accomplish this, the authors developed a prototype of a multi-stage (three-stage) valve, and then compared its performance against that of a single-stage valve across a wide range of hydraulic and magnetic stimuli. To summarize, improvements of the pinch-mode valve dynamic range are evident; however, at the same time, it is hampered by the presence of serial air gaps in the flow channel. [ABSTRACT FROM AUTHOR]

Robotic legs, such as for lower-limb exoskeletons and prostheses, have bimodal operation: (1) within a task, like for walking (high speed and low force for the swing phase and low speed and higher force when the leg bears the weight of the system); (2) between tasks, like between walking and sit–stand motions. Sizing a traditional single-ratio actuation system for such extremum operations leads to oversized heavy electric motor and poor energy efficiency at low speeds. This paper explores a bimodal actuation concept where a hydrostatic transmission is dynamically reconfigured using custom motorized ball valves to suit the requirements of a robotic leg with a smaller and more efficient actuation system. First, this paper presents an analysis of the mass and efficiency advantages of the bimodal solution over a baseline solution, for three operating points: high-speed, high-force, and braking modes. Second, an experimental demonstration with a custom-built actuation system and a robotic leg test bench is presented. Control challenges regarding dynamic transition between modes are discussed and a control scheme solution is proposed and tested. The results show the following findings: (1) The actuator prototype can meet the requirements of a leg bimodal operation in terms of force, speed, and compliance while using smaller motors than a baseline solution. (2) The proposed operating principle and control schemes allow for smooth and fast mode transitions. (3) Motorized ball valves exhibit a good trade-off between size, speed, and flow restriction. (4) Motorized ball valves are a promising way to dynamically reconfigure a hydrostatic transmission while allowing energy to be dissipated. [ABSTRACT FROM AUTHOR]

The paper shows that mechanical vibrations occur in a wide frequency range in the hydraulic systems operating in the real world. Hydraulic valves are also exposed to these vibrations. The paper gives examples of vibration sources and suggests that the influence of vibrations on hydraulic valves could be reduced. Particular attention was paid to the vibrating proportional distributor. The amplitude-frequency spectrum of pressure pulsation in a hydraulic system with a vibrating proportional distributor was analysed. During the tests, the frequency of external mechanical vibrations acting on the proportional distributor and their direction was changed.

Introduction: Bioprosthetic mitral valve thrombosis (BPMVT) following post-operative extracorporeal membrane oxygenation (ECMO) is a rare complication with high mortality. Case Report: A 75-year-old man with a flail posterior mitral leaflet underwent a bioprosthetic mitral valve replacement and was subsequently placed on central veno-arterial high flow ECMO following intractable shock after protamine administration. He developed BPMVT over the following 48 hr, which did not resolve with 3 weeks of systemic heparin. He was then treated successfully with 3 days of continuous low dose (1 mg/hr) Tissue Plasminogen Activator (TPA). He suffered no bleeding consequences and had a complete cardiac and end-organ recovery. Discussion: Slow TPA infusion may be an acceptable treatment strategy for alleviating thrombotic burden from a bioprosthetic valve, even in the post-operative setting. [ABSTRACT FROM AUTHOR]

Rational and energy efficient operation of pumps for pumping and transporting liquids used in difficult conditions of mining is possible due to the implementation and use of modern methods of managing the operating modes of the pumps. Nowadays, the methods and resources used to regulate the operating modes of pumping units do not meet modern requirements, and many mines still use outdated methods of regulating the operating modes of pumps, which entails significant energy losses and an increase in the cost of the transported liquid. In the article, the methods of reducing electricity losses and the impact on the performance of pumping units were considered. It is concluded that this method of regulating work makes it possible to operate pumping units in the working area. Our article considers and experimentally substantiates the possibility of achieving savings in electrical energy, as well as increasing the reliability of the operation of pumping units based on the use of modern methods of regulating operating modes.

Background: Both valvular heart disease (VHD) and atrial fibrillation (AF) frequently coexist. AF is an important cause of arrhythmias with a definitive cardiovascular morbidity. The use of either vitamin K antagonists (VKAs/warfarin) or direct oral anticoagulants (DOACs) (also known as new oral anticoagulants (NOACs)) has been the mainstay for preventing stroke and systemic embolism in patients with VHD and/or AF, and this has been broadly discussed. However, there are limited studies on anticoagulation therapy for patients with valvular atrial fibrillation (VAF). The main aim of this meta-analysis was to evaluate the outcomes (stroke–vascular events and intracranial bleeding) following DOAC and VKA treatment amongst patients with VAF. Methods: We identified clinical trials and observational studies published in the last 10 years. A systematic review and a meta-analysis were performed to evaluate the outcomes of patients with valvular atrial fibrillation following DOAC vs. VKA treatment. Data evaluation was performed using Review Manager 5.4; the endpoints were stroke–vascular events and intracranial bleeding following DOAC and VKA treatment amongst VAF patients. Risk ratios (RR) were evaluated with 95% confidence intervals. Using random effects models, forest plots were obtained. Heterogeneity was assessed by using the I2 statistic. Results: Eight studies were included in this metanalysis, and a total of fifteen thousand two hundred and fifteen patients (DOAC (8732) and VKA (6483)) were pooled. We found a significant risk reduction in stroke–vascular events when using DOACs in comparison with using VKAs (pooled RR: 0.76; 95% CI: 0.64–0.90, p = 0.002). A total of 14862 patients (DOAC (8561) and VKA (6301)) were pooled from a total of six studies for intracranial bleeding. We found a significant risk reduction in terms of intracranial bleeding when using DOACs in comparison with using VKAs (pooled RR: 0.43; 95% CI: 0.24–0.77, p ≤ 0.05). Conclusions: When compared to VKAs, DOAC agents were found to have less risk of stroke–vascular events and intracranial bleeding. Further prospective studies are essential to establish the efficacy and safety of DOAC agents in patients with various subtypes of VAF.

With the deterioration growth of water pipes, the frequency of identifying segments and unintended isolation in water distribution networks is expected to increase, because it can help identify the number of nodes that cannot be supplied and their locations when a failure occurs. Therefore, a methodology for identifying segments and unintended isolation was developed and verified using examples. In addition, a case study was conducted to confirm that the proposed methodology could be applied to actual fields. The proposed method only requires the node-based adjacency matrix K for identification, where the connectivity of the current network can be intuitively understood with the constructed matrices. Moreover, this methodology is easy to adopt using the single row-first search method. The proposed framework is compatible with the data storage format of hydraulic analysis software. Finally, the proposed methodology can be used in various research on configuring and analyzing water distribution networks. [ABSTRACT FROM AUTHOR]

Infective endocarditis (IE) during pregnancy is a rare condition that is associated with a high level of morbidity and mortality. The epidemiology, diagnosis, treatment, and prognosis have changed significantly in the last two decades. The declining incidence of rheumatic heart disease, improved life expectancy with congenital heart disease, advances in cardiac surgery and cardiac devices, rise in resistant microorganisms, complications of the opioid epidemic, and increasing maternal age are some of the many factors contributing to these changes. This article explores existing literature on the topic including case reports, case series, registry data, and clinical guidelines. The focus of this article is the evolving epidemiology, predisposing factors and preventative measures, clinical presentation, investigation, management, and potential complications of IE in pregnancy. Robust prospective data on the management of IE in pregnancy is lacking, and obtaining these data will be very challenging. It is imperative that international registries are used to provide data on best clinical practices and inform future clinical guidelines. Multimodal imaging should be incorporated in the investigation of complicated cases. A multidisciplinary approach to the management of this rare and life-threatening condition is essential to ensure the best outcomes for both the mother and the fetus. [ABSTRACT FROM AUTHOR]

Mayaro virus (MAYV) is an emerging mosquito-borne alphavirus that causes clinical symptoms similar to those caused by Chikungunya virus (CHIKV), Dengue virus (DENV), and Zika virus (ZIKV). To differentiate MAYV from these viruses diagnostically, we have developed a portable device that integrates sample preparation with real-time, reverse-transcription, loop-mediated isothermal amplification (rRT-LAMP). First, we designed a rRT-LAMP assay targeting MAYV's non-structural protein (NS1) gene and determined the limit of detection of at least 10 viral genome equivalents per reaction. The assay was specific for MAYV, without cross-reactions with CHIKV, DENV, or ZIKV. The rRT-LAMP assay was integrated with a sample preparation device (SPD) wherein virus lysis and RNA enrichment/purification were carried out on the spot, without requiring pipetting, while subsequent real-time amplification device (RAD) enables virus detection at the point of care (POC). The functions of our platform were demonstrated using purified MAYV RNA or blood samples containing viable viruses. We have used the devices for detection of MAYV in as short as 13 min, with limit of detection to as low as 10 GEs/reaction. [ABSTRACT FROM AUTHOR]

An iron alloy coating with gradient transition was sprayed on F304 stainless steel substrate by plasma spraying method and with a gradient material obtained by the material performance simulation software, and the effect of gradient transition on the microstructure, hardness and wear resistance of the coating was analyzed by comparing with the non gradient transition coating. The results show that both the gradient coating and the non gradient coating have wavy layered structure and are formed by highly flattened deformed particles overlapping each other. Micro metallurgical bonding was observed between the coating particles, and oxides were observed between the coating and the substrate, between the flat particles and inside the flat layer. The coating microstructure includes austenite phase, ferrite phase and carbides. The surface hardness of the gradient coating and the non gradient transition coating are basically similar, but there are obvious steep drop steps between the section hardness of the non gradient coating and the substrate hardness, while the section hardness of the gradient coating and the substrate hardness change gently, and the section hardness of the gradient coating is slightly lower than that of the non gradient coating. The wear rate of gradient coating is similar to that of non gradient coating at 400 °C, but it is lower than that of non gradient transition coating at 350 °C. The reason for reducing hardness changes and improving wear resistance of the coating may be related to the improvement of the microstructure and plasticity of the coating by the gradient layer, but more research is needed. [ABSTRACT FROM AUTHOR]

Background: Both valvular heart disease (VHD) and atrial fibrillation (AF) frequently coexist. AF is an important cause of arrhythmias with a definitive cardiovascular morbidity. The use of either vitamin K antagonists (VKAs/warfarin) or direct oral anticoagulants (DOACs) (also known as new oral anticoagulants (NOACs)) has been the mainstay for preventing stroke and systemic embolism in patients with VHD and/or AF, and this has been broadly discussed. However, there are limited studies on anticoagulation therapy for patients with valvular atrial fibrillation (VAF). The main aim of this meta-analysis was to evaluate the outcomes (stroke–vascular events and intracranial bleeding) following DOAC and VKA treatment amongst patients with VAF. Methods: We identified clinical trials and observational studies published in the last 10 years. A systematic review and a meta-analysis were performed to evaluate the outcomes of patients with valvular atrial fibrillation following DOAC vs. VKA treatment. Data evaluation was performed using Review Manager 5.4; the endpoints were stroke–vascular events and intracranial bleeding following DOAC and VKA treatment amongst VAF patients. Risk ratios (RR) were evaluated with 95% confidence intervals. Using random effects models, forest plots were obtained. Heterogeneity was assessed by using the I2 statistic. Results: Eight studies were included in this metanalysis, and a total of fifteen thousand two hundred and fifteen patients (DOAC (8732) and VKA (6483)) were pooled. We found a significant risk reduction in stroke–vascular events when using DOACs in comparison with using VKAs (pooled RR: 0.76; 95% CI: 0.64–0.90, p = 0.002). A total of 14862 patients (DOAC (8561) and VKA (6301)) were pooled from a total of six studies for intracranial bleeding. We found a significant risk reduction in terms of intracranial bleeding when using DOACs in comparison with using VKAs (pooled RR: 0.43; 95% CI: 0.24–0.77, p ≤ 0.05). Conclusions: When compared to VKAs, DOAC agents were found to have less risk of stroke–vascular events and intracranial bleeding. Further prospective studies are essential to establish the efficacy and safety of DOAC agents in patients with various subtypes of VAF. [ABSTRACT FROM AUTHOR]

The aim of the work is to present aspects related to the use of a double-acting cylinder with cushioning. In this manuscript two circuits using a double-acting cylinder with cushioning are presented: on one hand, a pneumatic circuit, and on the other, an electro-pneumatic circuit. The first pneumatic scheme contains the following devices: a double-acting cylinder with cushioning (Duacy 1), two throttle valves, 4/2- way valve type, an air filter and the compressed air supply. The second one is an electro-pneumatic circuit which consists of the following devices: double-acting cylinder (Duacy 2), two throttle check valves, a start-up valve with filter control valve, compressed air supply and two solenoid valves. [ABSTRACT FROM AUTHOR]

Background: Pulmonary atresia is a congenital heart defect that results from failure in the formation of the pulmonary valve that leads to right ventricular outflow obstruction, preventing the right heart ejection of blood to the lungs. It is also associated with a high incidence of chromosomal anomalies. Methods: A retrospective study of all infants diagnosed with pulmonary in Bahrain was undertaken. Pulmonary atresia was classified into pulmonary atresia with intact ventricular septum, pulmonary atresia in Tetralogy of Fallot, and pulmonary atresia in complex cyanotic heart defects. Short-term outcomes, survival, and associated genetics were analyzed. Results: 84 patients were diagnosed. 57 (67.9%) were males and 27 (32.1%) were females (p = 0.204). The median age at diagnosis was 25 days. Patients diagnosed with pulmonary atresia and complex cyanotic heart defects had the highest early survival rate. The early survival rate of patients diagnosed with pulmonary atresia with intact ventricular septum was lowest (p = 0.0179). Twenty-two patients (26.19%) had chromosomal anomalies. The DiGeorge syndrome was found in 18 patients, and 2 with Down Syndrome and other dysmorphisms in 2. 19 (86.36%) with chromosomal anomalies had pulmonary atresia and Tetralogy of Fallot, and 3(13.64%) with pulmonary atresia and complex cyanotic heart defects (p = 0.027). Conclusions: Pulmonary atresia is a rare but serious congenital heart defect. The lowest short-term survival is in those with intact intraventricular septum. There is a high incidence of chromosomal deletion of 22q11 leading to DiGeorge syndrome in those with Tetralogy of Fallot with pulmonary atresia. Early catheterization and surgical techniques are effective palliation for short-term survival. [ABSTRACT FROM AUTHOR]

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The valve assembly used in nuclear power plants is important safety-related equipment. In the new standard, the physical attributes are measured using a valve diagnosis test, which is used in the expansion to other non-tested valves using a quantitative test-basis methodology. With a motor-operated actuator, the state of stem's lubrication is related to physical attributes such as the stem factor and the friction coefficient. This study analyzed the numerical transient of fluid and solid lubrication with a squeeze film effect due to the loading rate on the stem and the stem nut using the experimental data. The differential equation that governs the motion mechanism of the stem and stem nut is established and analyzed. The flow rate, the fluid and the solid contact forces are calculated with the friction coefficient. Finally, we found that a change in the friction coefficient results from a change of the shear force in the solid contact mode during the interchange process between the solid contact mode and the fluid contact mode. The qualitative understanding of the squeeze film effect is expanded quantitatively for forces, thread surface distance, velocity, and acceleration, with consideration of the metal solid contact and fluid contact.

The exhaust valve seat face is a surface that degrades slowly as a result of mechanical and thermal stresses. There is extensive research on new materials for valves and for the improvement of valve production technology. This paper discusses the method of obtaining a filler metal made of Fe3Al intermetallic phase and the method of TIG hard-facing on a valve seating face made of H9S2 steel, evaluating the effects of essential hard-facing parameters. The resulting hard-facing build up was assessed in terms of quality using industrial radiography testing (RT).

The study discusses the issues of low durability of dies used in the first operation of producing a valve type forging from high nickel steel assigned for the application in motor truck engines. The analyzed process of manufacturing the exhaust valve forgings is realized in the coextrusion technology, followed by forging in closed dies. This process is difficult to master, mainly due to elevated adhesion of the charge material (high nickel steel – NCF3015) to the tool substrate as well as very high abrasive wear of the tool, most probably caused by the dissolution of hard carbide precipitates during the charge heating. A big temperature scatter of the charge during the heating and its short presence in the inductor prevents microstructure homogenization of the bearing roller and dissolution of hard precipitates. In effect, this causes an increase of the forging force and the pressures in the contact, which, in extreme cases, is the cause of the blocking of the forging already at the beginning of the process. In order to analyze this issue, complex investigations were conducted, which included: numerical modelling, dilatometric tests and hardness measurements. The microstructure examinations after the heating process pointed to lack of structure repeatability; the dilatometric tests determined the phase transformations, and the FEM results enabled an analysis of the process for different charge hardness values. On the basis of the conducted analyzes, it was found that the batch material heating process was not repeatable, because the collected samples showed a different amount of dissolved carbides in the microstructure, which translated into different hardnesses (from over 300 HV to 192 HV). Also, the results of numerical modeling showed that lower charge temperature translates into greater forces (by about 100 kN) and normal stresses (1000 MPa for the nominal process and 1500 MPa for a harder charge) and equivalent stresses in the tools (respectively: 1300 MPa and over 1800 MPa), as well as abrasive wear (3000 MPa mm; 4500 MPa mm). The obtained results determined the directions of further studies aiming at improvement of the production process and thus increase of tool durability.

The authors discuss the issue of engineering a special gear to change the power fluid pressure in hydraulic fracturing of strong rocks. The article describes the operation of the gear on the basis of implemented laboratory tests, and proposes the ways of eliminating deficiencies. The size and shape of choke grooves for the careful switching of the control valve subject to the power fluid flow rate are determined. The hydraulic circuit of the jet-control slide-type valve is developed. It allows improved accuracy and precision of the valve switching. [ABSTRACT FROM AUTHOR]

As for the complex shock vibration characteristics, the issue of difficult to extract the characteristic information of reciprocating compressor valve, a fault diagnosis method combining informational variational mode decomposition (IVMD) and cyclic modulation spectrum (CMS) is proposed. In this paper, the Bayesian information criterion (BIC) is optimized for the VMD decomposition parameter firstly, and the obtained IVMD algorithm is applied to decompose the signal into intrinsic mode functions (IMFs). Secondly, the signal is reconstructed with the correlation coefficient. Finally, the CMS algorithm is utilized for the reconstructed signal analysis, from which main spectral features of the carrier frequency and cyclic frequency on the cyclic modulation spectrum are obtained. The characteristic information of the signal is high-lighted with the amplitude and relationship of the frequency feature. The effectiveness and superiority of the method in the diagnosis of reciprocating compressor valve faults are demonstrated with the numerical simulation and experimental analysis. [ABSTRACT FROM AUTHOR]

The flow of working medium through the drain valve of a helicopter fuel system is simulated by means of ANSYS CFX software. A method is developed for computer modeling and optimization of the valve design. [ABSTRACT FROM AUTHOR]

Thalassiosira allenii is reported for the first time from marine phytoplankton of the Russian far East. Five strains representing three morphological variants of T. allenii, from three locations in the Sea of Japan, were investigated. The D8–D10 domain of LSU rDNA and rbcL of T. allenii were sequenced for the first time. Three morphological forms of T. allenii showed completely identical rbcL sequences and distinctly different nuclear rDNA sequences. The genetic differences between morphotypes were determined by the number of allelic variants of LSU rDNA, one of which was common to all studied strains. Two different types of the D1–D3 domain and three different types of the D8–D10 divergent domain were detected in the cultured strains of T. allenii. The three morphotypes are described in detail and compared. One allele of D1–D3 and one allele of D8–D10 were identified in the strains of T. allenii from two stations in Ussuri Bay. Two and three alleles of the D8–D10 domain were identified in the strains with an ambiguous morphotype and in T. allenii var. striata, respectively, from one station in Amur Bay. Subdivision of T. allenii into morphotypes based on morphology matched that based on molecular-genetic analyses using D8–D10 LSU rDNA. Caution is recommended in using LSU rDNA sequences and rbcL divergence as the principal criterion for delimiting and metabarcoding T. allenii varieties/morphotypes. The lack of genetic differentiation in rbcL, and the presence of clear intra-specific genetic differentiation among morphotypes in two regions of LSU rDNA suggest a link between morphological differences and the nuclear genome. The D8–D10 domain of LSU rDNA appears more suitable for discriminating morphotypes within T. allenii. The rbcL is an effective marker for recognizing T. allenii at species level, but not at infraspecific level. [ABSTRACT FROM AUTHOR]