Maximum Flow Research Articles

Performance evaluation of controlled low-strength blended cement concrete modified with recycled waste materials

Purpose This work aims to investigate the feasibility of recycling waste plastic (polyethylene terephthalate) as a coarse aggregate for producing blended cement concrete modified with fly ash and pond ash. Design/methodology/approach The low, medium and high controlled strength blended cement concrete modified with varied proportions of fly and pond ashes were produced. Manufactured sand and recycled plastic coarse aggregate (RPCA) replaced normal fine and coarse aggregates. Concrete samples were tested for workability, mechanical and durability characteristics. Microstructural analysis was performed on cement concrete blended with fly and pond ashes and compared to conventional concrete samples. Findings All concrete mixes showed better flowability with values greater than 200 mm. Besides, the maximum flow time was approximately 8 s. The wet density of blended cement concrete-RPCA-based concretes was approximately 30% lower than that of conventional concrete. The compressive strengths of the controlled strength mix at 7 and 28 days were within the specified ranges. While the conventional concrete had slightly higher permeability, the blended cement concrete-RPCA-based concretes had better thermal resistivity and lower thermal conductivity. The scanning electron microscopy analysis revealed the densification of the microstructure due to the filler effects of fly and pond ashes. Originality/value This study establishes the prospects of substituting RPCA with normal coarse aggregate in the production of controlled low-strength blended cement concrete, offering benefits of structural fill concrete, lower permeability and thermal conductivity, higher thermal resistivity and reduced density and shrinkage.

Abstract Su1201: Alteration in cerebrospinal fluid flow in out-of-hospital cardiac arrest patients who underwent target temperature management.

Background: Various parameters of cerebrospinal fluid (CSF) flow measured through magnetic resonance imaging (MRI) flowmetry are utilized to assess the progression of certain diseases. Our study evaluated changes in CSF flow using MRI flowmetry in survivors of out-of-hospital cardiac arrest (OHCA) who underwent target temperature management (TTM). Methods: This prospective observational cohort study was conducted from May 2023 to April 2024 at a single center. We performed Wilcoxon signed-rank tests to compare maximum velocity (V max ), stroke volume (SV), maximum flow (flow max ), and stroke distance measured immediately after return of spontaneous circulation (ROSC) with those measured at 72 h after ROSC. Results: Of the 20 patients enrolled, 7(35.0%), 1(5.0%), 2(10.0%), 5(25.0%) and 5(25.0%) patients had CPC scores of 1, 2, 3, 4, and 5, respectively. V max , SV, flow max , stroke distance measured immediately after ROSC were 3.41 (2.03~4.96), 14.00 (4.00~23.38), 0.09 (0.06~0.22), -0.07 (-0.17~0.05), respectively. V max , SV, flow max , stroke distance measured at 72h after ROSC were 5.26 (2.76~9.28), 24.00 (10.38~42.25), 0.14 (0.08~0.31), -0.07 (-0.18~0.03), respectively. Although V max , SV, and flow max measured at 72 h after ROSC were statistically significantly higher compared to those measured immediately after ROSC (p = 0.002, 0.02, 0.002), there was no significant difference between the stroke distances measured immediately after ROSC and at 72 h after ROSC (p = 0.43). Additionally, the caudocranial direction of CSF flow was observed in 13 (65.0%) patients immediately after ROSC, and in 14 (70.0%) patients 72h after ROSC. Conclusion: This study demonstrated that alterations in cerebrospinal fluid flow were observed in OHCA patients. However, Further studies are needed to determine whether there are differences in alteration in CSF flow based on neurological prognosis.

Asymmetry of Directed Brain Connectivity at Birth in Low-Risk Full-Term Newborns

Purpose: Functional connectivity hubs were previously identified at the source level in low-risk full-term newborns by high-density electroencephalography (HD-EEG). However, the directionality of information flow among hubs remains unclear. The aim of this study was to study the directionality of information flow among source level hubs in low-risk full-term newborns using HD-EEG. Methods: A retrospective analysis of HD-EEG collected from a prospective study. Subjects included 112 low-risk full-term (37–41 weeks' gestation) newborns born in a large delivery center and studied within 72 hours of life by HD-EEG. The directionality of information flow between hubs at the source level was quantified using the partial directed coherence in the delta frequency band. Descriptive statistics were used to identify the maximum and minimum information flow. Differences in information flow between cerebral hemispheres were assessed using Student t-test. Results: There was higher information flow from the left hemisphere to the right hemisphere hubs (p < 0.05, t-statistic = 2). The brainstem had the highest information inflow and lowest outflow among all the hubs. The left putamen received the lowest information, and the right pallidum had the highest information outflow to other hubs. Conclusions: In low-risk full-term newborns, there is a significant information flow asymmetry already present, with left hemisphere dominance at birth. The relationship between these findings and the more prevalent left hemisphere dominance observed in full-term newborns, particularly in relation to language, warrants further study.

The relationship between land use change and flood flows, a case study in a transboundary watershed

Introduction: Introduction: The HEC-HMS model was applied in the transboundary basin of the Zarumilla River (Ecuador – Peru) to simulate the flows that would occur during maximum precipitation events. Methodology: The model integrated the precipitation determined by intensity equations, the infiltration defined by the curve number, the rain - runoff transformation by unit hydrographs, the hydrological routing calculated by applying Muskingum - Cunge and was calibrated by a frequency analysis using the hydrometric information available. Results: The model was executed satisfactorily and the resulting maximum flows at the outlet of the basin varied between 1.100 m3/s and 1.670 m3/s depending on the return period. A land use scenario for the year 2027 was generated using information from 2014 and 2017 that was evaluated with the model. Discussion: The transitions with the largest area of influence observed were pasture to crop, forest to crop and crop to pasture. Other classifications do not present a significant change. Conclusions: The flows calculated with the coverage of the generated scenario are lower than those calculated for 2017, due to the expansion of crops, which are mostly fruit crops. Despite this, the variation in flow rates was not very significant.

Atomistic and Theoretical Insights on Nanoprecipitates-Controlled Strengthening Behavior for Optimum Mechanical Performance in Nanotwinned NiCoCr Alloys

Abstract The nanoprecipitates and nanotwins enable to improve the mechanical performance of NiCo-based alloys. In this work, the molecular dynamics (MD) simulations are performed to investigate the strengthening mechanisms of nanotwinned medium-entropy NiCoCr alloys with various distributions and volume fractions of nanoprecipitates. MD simulations reveal that mechanical performance for the precipitates located in twin boundaries is better than that located in the twin lamellae. The precipitate-induced strengthening makes the nanotwinned NiCoCr alloys to achieve the maximum flow stress during increasing the precipitate volume fraction. The influences of volume fraction and distribution of the precipitate on winding and cutting mechanisms are analyzed comprehensively. The dislocation winding behavior, hindered twin boundaries deformation, and the adjacent precipitates connection control the precipitate strengthening mechanisms. A dislocation-based theoretical model is developed to forecast the size-dependent flow stress of nanotwinned metals with nanoprecipitates, in which the Orowan bypass mechanism and the dislocation pile-up behaviors are involved. The relationship between the microstructural size and the flow stress of nanotwinned metallic materials with nanoprecipitates is explored. The predictions for the flow stresses varied with the precipitate volume fraction are agreeable well with the results of MD simulation. The predicted maximum flow stresses and the corresponding critical volume fractions of nanoprecipitates are sensitive to the microstructural sizes.

ESTIMATION OF THE CLEANING TIME OF THE BOTTOM-HOLE ZONE OF WELLS IN CONDITIONS OF UNCERTAINTY

The aim of the work is to analyze changes in the maximum optimal flow rates of wells operating various groups of productive formations of the Volga-Ural oil and gas province under conditions of uncertainty of geological and field data. The relevance of the work is due to the deterioration of the structure of residual oil reserves and the need for the most efficient extraction of liquid hydrocarbon resources, optimization of design methods for various treatments of the bottomhole formation zone. Using geological and statistical modeling systems, the timing of cleaning the bottomhole zones of wells from drilling products was determined at the time they reached their maximum optimal flow rate in conditions of deposits confined to various stratigraphic horizons, and appropriate models of changes in productivity coefficients were constructed. The factors influencing the recovery time of the real properties of the reservoir at the point of opening it by the well, which, among other things, determines the profitability of the process of selecting residual oil reserves, have been established. Among them, the most relevant and necessary for the implementation of an integrated approach to computer support procedures for the development of oil fields are the productivity of wells, fracturing of formations, their proximity to a particular tectonic-stratigraphic complex, geological, physical and physico-chemical properties of formations and their saturating fluids. For the deposits of the Famensk tier of deposits of the Volga-Ural oil and gas province, a multiple decrease in the time of removal of reaction products after hydrochloric acid exposure at objects with low fracturing has been established. At the same time, additional processing of the bottomhole formation zone within areas with high drilling density does not affect the total cleaning time of the bottomhole zone of wells. Stimulation of the removal of drilling mud filtrate and additional products of formation reactions by injection of hydrochloric acid compositions under certain conditions can lead to a decrease in the actual productivity of wells due to the introduction of less developed and dead-end cracks into the drainage process. The existence of the specifics of the procedure for cleaning the bottomhole formation zone depending on the geological and physical parameters of productive formations is substantiated and various patterns of changes in the productivity coefficient depending on the time of wells reaching the maximum optimal flow rate are revealed. The results obtained make it possible to make informed technological decisions to improve the efficiency of oil production, including in conditions of uncertainty, which may be caused by the lack of the necessary volume of hydrodynamic studies of wells.

Conceptual groundwater model of the north-eastern flanks of Mount Kenya

Despite serious concerns over declining river flows and prolonged dry spells in the north-eastern region of Mount Kenya and the Ewaso Ng’iro River watershed many aspects of the groundwater system remain unexplored. In particular, the recharge-discharge dynamics of the Ewaso Ng’iro River have not been studied, and no conceptual groundwater model currently links the recharge areas in the high-elevation humid regions to the drier lowlands. This study aims to address this significant knowledge gap by assessing the recharge-discharge dynamics of the Ewaso Ng’iro River and identifying the relevant groundwater subsystems and the main flow paths within the various lava layers constituting the aquifer system. Hydrochemical and stable isotope analyses revealed three distinct subsystems with slightly different chemistries and different recharge zones, all of recent meteoric origin. Groundwater from Mt. Kenya is of the HCO3-Na-Mg-Ca type with no dominant cations, whereas groundwater from the Nyambene Range, the other surrounding volcanic hills in the area, is of the HCO3-Na type. Groundwater in the third subsystem in between is of the HCO3-Mg type and is confined or semi-confined. In this area, carbon-13 analysis showed a strong influence of mantle-derived CO2 on the groundwater chemistry (very high electrical conductivity and left-shifted oxygen-18 ratios). Finally, major ions and stable isotopes (ẟ18O and ẟ2H) confirmed that during the dry season, the river is entirely groundwater-fed, with the Mt. Kenya subsystem contributing half of the maximum river flow rate of 800 l/s.

Efficacy of the Rezūm System for lower urinary tract symptoms in patients with benign prostatic hyperplasia: Long term results from a single centre prospective study.

Benign prostatic hyperplasia (BPH) is a prevalent urological condition leading to lower urinary tract symptoms. Minimal invasive surgical treatment (MISTs) such as Rezūm System are emerging aiming to relieve symptoms. We present results from a single centre prospective study. We prospectively followed patients undergoing Rezūm between 2021 and 2023 from a single centre. International Prostate Symptom Score (IPSS), functional outcomes (maximum urinary flow rate (Qmax) and post-void urinary residual (PVR) and International Index of Erectile Function-5 (IIEF-5) were assessed at 3, 6, 12 and 24 months. Anterograde ejaculation was assessed at 12 months follow up. Linear mixed-effects models (LMMs) for repeated measures were applied to assess differences in the IPSS, maximum flow rate (Qmax), PVR, and International Index of Erectile Function-5 (IIEF-5) from baseline (t0) to 3, 6, 12 and 24 months. Results: After adjusting for prostate volume and symptoms severity, significant differences were observed at 3, 6, 12 and 24 months for IPSS (p < 0.001), Qmax (p < 0.001), PVR (p < 0.001) and IPSS-QoL (p < 0.001) from baseline. No statistically significant changes were found in the IIEF-5 scores at 3, 6, 12 and 24 months from baseline. Anterograde ejaculation remained in 98% of patients after treatment. In conclusion, the study's findings indicate that patients undergoing Rezūm treatment experience sustained improvements in IPSS, Qmax, PVR and IPSS-related quality of life up to 24 months following the intervention. Anterograde ejaculation remained in 98% of patients after treatment.

Non-Conservative Maximum Flow by Centiles-Method in Uncertain Network

The flow maximization problem being a leading problem in network optimization is widely studied with many applications. In this work, we find the maximum flow pulled out from the source and sent to the sink using the uncertainty theory. We develop a flow function to get maximum flow for the network having uncertain arc capacities and sufficient storage capacities at the intermediate vertices. The centiles-method is used to find the maximum flow value and an algorithm is proposed to get non-conservative maximum flow. The result is also illustrated by an example. The flow values are compared graphically to see the dominance of the non-conservative maximum flow over the conservative maximum flow.

Computed tomography radiomics-based prognosis prediction of patients with chronic obstructive pulmonary disease

Objectivethe objective of this study was to develop a predictive model for pulmonary ventilation function in patients with chronic obstructive pulmonary disease (COPD) utilizing computed tomography (CT) and pulmonary function parameters. Material and methoda retrospective analysis was conducted on 90 patients with COPD from our hospital, who were divided into Group I (AG, normal pulmonary function), Group II (BG, mild ventilation dysfunction), Group III (CG, moderate ventilation dysfunction), Group IV (DG, severe ventilation dysfunction), Group V (EG, very severe restrictive ventilation dysfunction), and Group VI (FG, very severe mixed ventilation dysfunction) according to pulmonary function. The imaging and pulmonary function indicators of the subjects were analyzed. Resultas lung dysfunction worsened, structural changes in the lungs on CT images also progressively worsened, manifesting as an enlargement of emphysematous areas, a decrease in lung field homogeneity, changes in lung tissue density and structure, and a reduction in lung field volume. Maximal expiratory flow (MEF) when 75%, 50% of the forced vital capacity (FVC) remained in the lung, i.e. MEF75%, MEF50%, and maximum mid-expiratory flow (MMEF75%-25%) were most highly correlated with ventilation dysfunction. Conclusionthe severity of pulmonary ventilation dysfunction in patients with COPD can be better predicted by CT imaging and pulmonary function examination indicators.

Efficacy and safety of prostatic urethral lift according to preoperative urinary retention and prostate volume: A Japanese real-world multicenter data.

Prostatic urethral lift (PUL) for benign prostatic hyperplasia has recently been initiated in Asia; therefore, few studies with real-world data have been reported. This study evaluated the efficacy and safety of PUL using Japanese real-world multicenter data. Indications for PUL were based on relevant guidelines in Japan. The preoperative patient status, postoperative progress at 1 and 3 months, and perioperative complications were evaluated. Also, we compared preoperative urinary retention and nonurinary retention patients, and prostate volumes <30, 30 to <50, and ≥50 mL. A total of 160 patients were included in the study. The mean age was 75 years and the mean prostate volume was 44 mL. The International Prostate Symptom Score, quality of life score, maximum flow rate, and postvoid residual volume significantly improved 1 and 3 months postoperatively compared to preoperatively. The catheter-free rates in the preoperative urinary retention group were 58.1%, 72.1%, 83.7%, and 88.4% on postoperative days 1, 7, 30, and 90, respectively. The catheter-free rates in the nonurinary retention group were 94.9%, 98.3%, and 100% on postoperative days 1, 7, and 14, respectively. The group with a prostate volume ≥50 mL had a longer operation time and used significantly more implants; however, no difference was observed in the postoperative urinary status among the three groups. PUL can be considered a safe and effective procedure for both preoperative urinary retention and nonurinary retention patients with prostate volumes <100 mL in older patients with comorbidities.

Experimental research on nonlinear vibration characteristics of double-layer mining string for deep-sea hydrate extraction under internal and external flow excitation

The vibration mechanism of the deep-sea hydrate mining string is extremely complex due to the combined effects of internal gas–liquid solid multiphase flow, structural contact collision, soil creep effect, and external ocean random load. Based on this, using the principle of similarity, a simulation experimental platform for the vibration of double-layer mining riser in deep-sea hydrate wells under internal and external flow excitation is developed, considering the vortex-induced effect of external flow field on the mining riser in the ocean section (which can simulate a maximum ocean flow velocity of 0.5 m/s), the three-phase flow-induced effect of gas–liquid–solid inside (which can simulate a maximum flow velocity of 2.0 m/s), and the coupling effect of mining string–conductor anchor node (CAN)–seabed. The influence of particle size, phase ratio, three-phase flow, and external flow velocity on the vibration response characteristics and nonlinear behavior of mining string are investigated. It is found that the vibration of vertical string is significantly affected by external ocean currents and internal three-phase currents. The vibration displacement amplitude of the horizontal section (average 0.08 mm) is significantly smaller than those of the vertical section (average 70 mm). The strong vibration positions of the vertical and horizontal sections of the mining string are different, in that the vertical section is mostly located below the middle section (just at 1800–2400 mm), while the horizontal section is mostly located at the three-phase inlet (just at 500 mm). The vertical section of the mining string presents a motion trajectory of oblique straight line, wide oblique straight line, or approximately wide oblique straight line, while the horizontal section is mostly a chaotic trajectory or an “8”-shaped chaotic trajectory. The decrease in particle mesh size and the increase in solid-phase proportion are reflected in the difficulty and accumulation of particle transport, leading to an increase in vibration displacement, as well as a decrease in vibration displacement amplitude and vibration energy. When the particle size set as 50 mesh, the displacement of mining string is largest, just for 110 mm of vertical section and 0.08 mm of horizontal section. The increase in the proportion of gas phase will lead to changes in the flow state of multiphase flow, which will affect the vibration displacement amplitude of the mining string to varying degrees. The increase in three-phase flow velocity further induces vibration of the mining string, and when the flow velocity is between 1.5 and 1.75 m/s, it will resonate with the string system, resulting in a sudden increase in the amplitude of vibration displacement. The research results can effectively guide operations and improve the service life of deep-sea hydrate mining riser.

Mixed-integer programming models and heuristic algorithms for the maximum value dynamic network flow scheduling problem

Various applications in contested logistics and infrastructure restoration require dynamic flow solutions characterized by a schedule of network flows consecutively transmitted over a sequence of successive periods. For these schedules, we assume flows transmit via arcs during periods while flows reside at nodes from one period to the next. Within this context, we introduce the Maximum Value Dynamic Network Flow Problem (MVDFP) in which we seek to maximize the cumulative value of a non-simultaneous network flow schedule that accumulates node value whenever some minimum amount of flow resides at a node between periods. For solving the MVDFP, we first introduce a large mixed-integer program (MIP). As this MIP can become computationally-expensive for large networks, we present a trio of computationally-effective, easy to implement heuristic approaches that solve a series of smaller, more manageable MIPs. These heuristic approaches typically determine high-quality solutions significantly faster than the MIP obtains an optimal solution by dividing the full network flow schedule into a sequence of consecutive shorter network flow subschedules. In many cases, at least one of our heuristic approaches produces an optimal solution in a fraction of the MIP’s computational time. We present extensive computational results to highlight our heuristics’ efficacy, discuss for what instances each approach may be most applicable, and detail future research avenues.

The joint effect of changes in urbanization and climate on trends in floods: A comparison of panel and single-station quantile regression approaches

Estimates of annual maximum (peak) flow quantiles are needed for basins undergoing changes in both urbanization and climate. Most previous work on the effect of urbanization on peak flows has considered urbanization alone and only the spatial variation in flood quantiles or its mean temporal effect, and most work on the effect of nonstationarity in climate has focused on single-station analyses, which give uncertain results for extreme quantiles. To address these gaps, three approaches to the statistical estimation of the joint effects of changes in impervious cover and climate on the estimation of peak-flow quantiles were compared: single-station quantile regression; a fixed effect panel-quantile regression (pQR) method using a location (mean) shift to homogenize the panel; and a location-scale panel regression model (pQRmom), which accounts for both scale (variance) and location effects. The different approaches were applied to a dataset consisting of instantaneous annual peak flows from 127 minimally nested basins in the midwestern United States with at least 4 % change in imperviousness. The annual maximum daily discharge from a water-balance model was selected as the primary climate predictor; in addition, to provide a comparison of climate predictors, precipitation was also considered. The coefficients from single-station regressions were usually sufficiently certain to determine the effects of climate variation but usually too uncertain to estimate the effects of urbanization. The panel-quantile regression approaches give much more certain results, but their estimates of quantile dependence differ: although both indicate urbanization effects decreasing with decreasing annual exceedance probability (AEP), the pQRmom urbanization coefficients are insignificantly different from zero for AEPs less than 0.10, whereas the pQR coefficients remain positive and are significant except for AEP = 0.01, the smallest AEP value considered. Although the location-scale structure of the pQRmom approach has less flexible quantile dependence than the pQR approach, the pQRmom approach has somewhat lower overall error, and it is found that by subsetting the dataset to homogenize the scale effects, the pQR and pQRmom results become similar, indicating the insignificant urbanization coefficients for small AEPs of the pQRmom results are likely correct for the study dataset.

Has unsustainable groundwater use induced low flow regimes in the Urucuia Aquifer System? An urgent call for integrated water management

Groundwater depletion in the Urucuia Aquifer System (UAS) has concerned the Brazilian water agencies since it is the principal water source in the arid length of the São Francisco river. In contrast, the irrigation fields increasing and uncertainty regarding climate variability have impaired the management of this important hydrograph region of Brazil. Therefore, the proper management of the UAS relies on the correct definition of the factors that are impacting most of the ground and surface waters, i.e., whether they are from climate or anthropogenic activities. Relying on Artificial Intelligence (AI) modeling and hydrological signatures, this study proposed a methodology to disentangle the role of climatic variability and groundwater pumping on streamflow dynamics by rebuilding natural time series in four watersheds within the UAS’s boundaries. By comparing the natural to the observed streamflow time series, the long-term 90th percentile (Q_90) discharge, from which 80% can be granted for multiple uses in the State of Bahia, decreased by up to 50% in the UAS. Yet, the watersheds’ productivity, given by the 90% specific yield, ranged from -52.3% (3.8 L/s.km2 to 1.8 L/s.km2) to -74.0% (23.4 L/s.km2 to 6.1 L/s.km2). Low flow duration was ∼ 1,650 days in natural conditions and increased to 10,354 days in the current land use and cover scenario. Changes in the maximum low flow duration length ranged from 191.7% to 1,315.7%, and in the low flow, deficits were up to 7,150%. These results highlight that groundwater pumping is the principal factor of the UAS’s dryness since climate variability could not track streamflow decreases. However, climate variability is secondary because of the intensification of the atmosphere demand. Although it is a Brazilian application, the proposed methodology can be applied in other aquifer systems to guide decision-makers' management strategies worldwide.

Water vapor thermal therapy (Rezūm System) in patients with large prostates: results from a prospective comparative study.

Rezūm is a novel minimally invasive surgical technique (MIST) useful for BPH patients with medium-sized prostate (30-80 cm3) refractory to medical treatment. The aim of this study was to evaluate the efficacy and safety of Rezūm as a treatment option in large-sized prostates (>80 cm3). We performed a prospective, comparative, single-center study from June 2022 to June 2023, including consecutive patients undergoing surgery with the Rezūm System. Enrolled men were classified into two subgroups based on prostate size: medium prostate (MP) (30-80 cm3) and large prostate (LP) (≥80 cm3). Inclusion criteria included an International Prostate Symptom Score (IPSS) Total score of ≥ 8 points. International Prostate Symptom Score (IPSS), maximum urinary flow rate (Qmax), post-void residual (PVR), and International Index of Erectile Function 5-item version (IIEF-5) were collected at baseline and at three, six, and 12 months post-procedure. Ejaculation presence was assessed at 3 months. Post-operative complications were described using the Clavien-Dindo (CD) classification. The primary outcome was the IPSS-Total score, with intraoperative and postoperative CD grade ≥III complications as secondary outcomes. One hundred and twenty-one patients (PV 78.2±32.1 mL) were included in the study, 51 large prostate (LP) and 70 medium prostate (MP). The IPSS-Total score and Q<inf>max</inf> showed a statistically significant (P<0.0001) improvement at 3, 6, and 12 months respectively. PVR decreased at 3, 6, and 12 months; however, only at 3 months this variation was statistically significant (P<0.0001). At 3-month follow-up, anejaculation was detected in (3; 5.8% and 1; 1.4%) patients in LP and MP group respectively (P=0.86). IIEF-5 significantly improved 3 months after surgery in the LP subgroup (P<0.0001). Rezūm water vapor therapy appears to be effective for treating BPH in larger prostates. Additionally, it demonstrates a low risk of impairing sexual function, indicating a favorable safety profile.

Angiographic reconstructions of CT perfusion for occlusion detection in ischemic stroke

BackgroundBoth CT angiography and CT perfusion involve the administration and tracking of a contrast medium bolus for different purposes. In this study, we aim to compare the diagnostic accuracy and subjective image quality of CTP-angiographic reconstructions with conventional CTA for occlusion detection in ischemic stroke patients. MethodsIn this retrospective study, patients with a final diagnosis of ischemic stroke and who underwent both CTA and CTP from September 2020 up to and including September 2021 were included. CTP-AR was reconstructed from the 1 mm CTP series at the time of maximum arterial inflow. Three readers with different levels of experience assessed both CTA and CTP for occlusion detection, expressed certainty, and rated subjective image quality. The reference standard was set at the consensus meeting. Pooled sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. Differences in subjective and objective image quality and certainty were assessed using Kendall’s tau correlation and paired samples t-tests. ResultsIn total, 107/210 included patients had an occlusion based on our reference standard. Pooled sensitivity and specificity for occlusion detection were 90 % (95 %CI 85–93 %) and 94 % (95 %CI 90–97 %) for CTA, and 89 % (95 %CI 84–93 %) and 93 % (95 %CI 89–96) for CTP-AR, respectively. The pooled certainty did not significantly differ between CTA and CTP-AR (P=.43). The pooled subjective image quality scores significantly differed between CTA and CTP-AR (τ = 0.3, P < 0.001), where one reader rated subjective image quality higher in CTA and two readers in CTP-AR. ConclusionCTP-AR has comparable diagnostic accuracy to conventional CTA imaging for occlusion detection in ischemic stroke patients. Thus, using CTP-AR instead of CTA plus CTP may conserve contrast medium.

Correlation of Impulse oscillometry system indices with conventional pulmonary function tests in patients with obstructive pulmonary ventilation dysfunction

Objective: To investigate the correlation between impulse oscillometry system examination indicators and conventional pulmonary ventilation function. Methods: The pulmonary ventilation function data of 10 883 patients from January 1, 2020 to December 31, 2022 at Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology were included. The one-second rate [ratio of forced expiratory volume in the first second (FEV1) to forced vital capacity (FVC)] measured as a percentage of the predicted value was ≥92% for the control group (n=3 478) and <92% for the pulmonary obstruction group (n=7 405). The obstruction group was subdivided into five groups according to the degree of pulmonary dysfunction: mild group (n=3 938),moderate group (n=1 142),oderate-severe group (n=917),severe group (n=737),and extremely severe group (n=671). Conventional pulmonary ventilatory function FVC, FEV1, one-second rate, and forced expired flow at 50% of FVC (MEF50%), forced expired flow at 75% FVC (MEF25%), maximal mid-expiratory flow (MMEF), peak expiratory flow (PEF), and pulsed oscillation pulmonary function test were detected in both groups of patients. Impedance at 5 Hz (Z5) means total respiratory resistance, resistance at 5 Hz (R5) means total airway resistance, reactance at 5 Hz (X5) indicates the elastic recoil of the peripheral airways, and resistance at 20 Hz (R20) represents resistance of the central airways. R5-R20 reflects resistance in the small airways. Additionally, peripheral resistance (Rp), respiratory resonance frequency (Frex), and area under the reactance curve (Ax) were also measured. Correlation between the indicators of the two groups and the sensitivity and specificity of the impulse oscillometry system parameters for the diagnosis of obstructive pulmonary ventilation dysfunction were analyzed. Results: Pulmonary function force expiratory volume in the first second as a percentage of predicted value (FEV1%Pre) [80.10 (54.95,97.10)%],one-second rate [62.43(48.67, 67.02)%],MEF50% [1.33 (0.62,1.97)L/s],MEF25% [0.28 (0.17,0.41)L/s], MMEF [0.85 (0.43,1.29)L/s],and PEF [5.64 (3.73,7.50)]L/s in the obstruction group were significantly lower than those in the control group (P<0.05). The differences within the subgroups of the obstruction group were also significant (P<0.05). Pulsed oscillation Z5 [0.42 (0.33,0.55)kPa·L-1·s-1],Rp [0.25 (0.20,0.45)kPa·L-1·s-1], R5 [0.39 (0.31,0.49)kPa·L-1·s-1], R20 [0.28 (0.24,0.34)kPa·L-1·s-1], R5-R20 [0.09 (0.05,0.17)kPa·L-1·s-1],Frex [16.32 (13.07,20.84)Hz], and Ax [0.67 (0.28,1.64)] indices in the obstruction group were significantly higher than those in the control group. X5 [-0.14 (-0.23, -0.10)kPa·L-1·s-1] was significantly lower than that in the control group (P<0.05). Z5, Rp, X5, R5, R5-R20, Frex, and Ax were statistically significant between different degrees of obstruction in the obstruction group (P<0.05). The impulse oscillometry system parameters Z5, Rp, R5, R20, R5-20, Frex, and Ax were negatively correlated with the indices of conventional pulmonary ventilation (r=-0.21-0.68, P<0.05), and the parameter X5 was positively correlated with the indices of conventional pulmonary ventilation (r=0.41-0.68, P<0.05). The pulsed oscillation pulmonary function test parameters X5 (58.60%-95.68%) and Ax (57.08%-98.06%) presented the best sensitivity; X5 (86.29%-98.82%), Frex (86.69%-94.71%), and Ax (88.10%-98.53%) displayed the best specificity; and R20 presented the worst sensitivity and specificity. The sensitivity and specificity were slightly better in female patients than in male patients. Conclusion: The technical parameters of the impulse oscillometry system showed significant correlation with relevant indices of conventional pulmonary ventilation function detection. These well reflect the changes of different degrees of pulmonary ventilation function and have greater significance for reference in evaluating the degree of pulmonary function impairment.

Outcomes of Double-Face Buccal Mucosal Urethroplasty for Treating Anterior Urethral Stricture in Adult Males.

To assess the results of double-face buccal mucosal graft urethroplasty (BMG) for treating anterior urethral stricture in adult males. An observational study. Place and Duration of the Study: Department of Urology, Sindh Institute of Urology and Transplantation, Karachi, Pakistan, from 2021 to 2022. The inclusion criteria were adult males, aged 15 to 70 years, with a previous surgical procedure for hypospadias and the presence of long penile and bulbar strictures measuring over 2 cm, resulting from a straddle injury. Forty-three patients were selected who underwent urethroplasty in 2021 and completed a one-year follow-up in 2022. Uroflowmetry (UFM) and the International Index of Erectile Function (IIEF) assessment data were obtained from the patients' medical records. Success was defined as the patient attaining catheter freedom and achieving a maximum flow rate exceeding 15 ml/sec after one year. The mean UFM at one year was 20.89 ml/s. Four patients underwent endo-urological intervention (direct visual internal urethrotomy), and one patient needed a second double-face urethroplasty. After one year, the double-face BMG urethroplasty achieved an overall success rate of 88.4%. Double-face BMG urethroplasty is a reliable and effective surgical technique for the treatment of near obliterative or obliterative long anterior urethral strictures. Buccal mucosal graft urethroplasty, Direct visual internal urethrotomy, Anterior urethral stricture, Buccal mucosal graft, Urethral dilatation.

Study on heat transfer and flow of molten pool during the deposition process of laser wire additive manufacturing

In the laser wire additive manufacturing process, the molten pool acts as the critical link between the wire and the deposited part. The heat transfer and flow behavior within the molten pool predominantly determine the quality of the final deposition. Under laser power ranging from 2400 to 3000 W, traverse speeds between 0.01 and 0.04 m/s, and wire feeding speeds from 0.03 to 0.08 m/s, three distinct flow states—single-swirl, double-swirl, and no-swirl—were observed with increasing heat input. Under the optimum process parameters, the molten pool with stable temperature distribution and orderly flow was obtained. In multilayer deposition, the implementation of a laser decay strategy mitigates steep temperature gradients, diminishes the Marangoni effect within the molten pool, and effectively reduces both heat accumulation and lateral flow. Consequently, the flow mode transitions from no-swirl to swirl, and the maximum flow velocity decreases by 40%.