Effect of Thickener Type on Change the Tribological and Rheological Characteristics of Vegetable Lubricants.

This paper presents the results of a study on the effect of the dispersed phase on the lubricating and rheological properties of selected lubricant compositions. A vegetable oil base (rapeseed oil) was used to prepare vegetable lubricants, which were then thickened with lithium stearate, calcium stearate, aluminum stearate, amorphous silica, and montmorillonite. Based on the results of the tribological tests of selected lubricating compositions, it was found that calcium stearate and montmorillonite have the most beneficial effect on the anti-wear properties of the tested lubricating greases, while silica thickeners (amorphous silica and montmorillonite) provide the effective anti-wear protection in compared to the lubricants produced on lithium and aluminum stearate. The lowest structural viscosity was found for grease thickened with montmorillonite. Much higher values of this parameter were observed for composition, where aluminum stearate was the dispersed phase, while the highest value of structural viscosity was observed for composition, where aerosol-amorphous silica was the thickener. The composition thickened with amorphous silica had the highest yield point value, while the composition in which montmorillonite was the dispersed phase had the lowest value. Dynamic viscosity decreases with temperature, which is characteristic of lubricants. No significant differences in dynamic viscosity were found for the lubricating compositions tested at temperatures above 50 [°C]. The most favorable rheological properties were observed for composition, which was produced using calcium stearate, as it allows the lowest dynamic viscosity at -20 [°C]. Lubricants produced with lithium stearate or aluminum stearate were characterized by higher viscosity at low temperatures. For grease, in which the lithium stearate was used as a thickener, the value of the elasticity index determines the weak viscoelastic properties of tested grease and a greater tendency to change structure under the influence of applied forces. For vegetable grease thickened with aluminum stearate, more than 15 times lower values of the MSD function were observed, and the calculated elasticity index value proves the stronger viscoelastic properties of the aluminum stearate grease in relation to grease thickened with the lithium stearate. The elasticity index value for grease thickened with amorphous silica was lower than for greases thickened with lithium and aluminum stearate, indicating its stronger viscoelastic properties in relation to these two greases. For grease composition prepared on the vegetable oil base and thickened with montmorillonite. The value of the elasticity index was lower than most of the tested grease compositions, without the composition, in which the calcium stearate was used as a thickener. Such results testify to moderately strong viscoelastic properties, which leads to the conclusion that the produced lubricant was a stable substance on changes in chemical structure under the influence of variable conditions prevailing during work in tribological joints.

(A)voiding misdiagnosis: prediction of detrusor underactivity vs. bladder outlet obstruction using pre-urodynamic nomogram in male patients with LUTS.

PURPOSE: Our study aimed to develop a noninvasive model using a combination of the set of clinical data and uroflowmetry (UFL) to differentiate between detrusor underactivity (DU) and bladder outlet obstruction (BOO) in non-neurogenic male patients with lower urinary tract symptoms (LUTS). METHODS: Data from 229 men with LUTS, diagnosed with DU or BOO on a pressure-flow study (PFS), were retrospectively analyzed, including medical history, Core Lower Urinary Tract Symptoms score (CLSS) questionnaire, UFL and PFS. Uni- and multivariate logistic regression were utilized for the prediction analyses. RESULTS: Of the cohort, 128 (55.9%) patients were diagnosed with DU. A multivariate logistic regression analysis identified less prevalent nocturia (OR 0.27, p < 0.002), more prevalent intermittency (OR 2.33, p = 0.03), less prevalent weak stream (OR 0.14, p = 0.0004), lower straining points in CLSS (OR 0.67, p = 0.02), higher slow stream points in CLSS (OR 1.81, p = 0.002), higher incomplete emptying points in CLSS (OR 1.31, p < 0.02), lower PVR ratio (OR 0.20, p = 0.03), and present features of fluctuating (OR 2.00, p = 0.05), fluctuating-intermittent (OR 3.09, p < 0.006), and intermittent (OR 8.11, p = 0.076) UFL curve shapes as independent predictors of DU. The above prediction model demonstrated satisfactory accuracy (c-index of 0.783). CONCLUSION: Our 10-factor model provides a noninvasive approach to differentiate DU from BOO in male patients with non-neurogenic LUTS, offering a valuable alternative to invasive PFS.

Real-Time Cone-Growth Model for Determination of Pharmaceutical Powder Flow Properties.

The flow properties of pellets or granules are crucial for further processing drug dosage forms. Optimal compression or filling of multiparticulate dosage forms into capsules is influenced by forces between discrete particles, which could be partially characterized by flow properties. Several techniques have been developed to examine flowability, including static and dynamic methods applying empirical studies and up-to-date chaos theory; however, the newest methods seem only to be powerful with the supplementation of empirical principles. Our experiments try to refine both the technique of analysis and the methods, by finding new, alternative ways. Our approach to the flowability measurements was to set up a dynamic time-dependent model that combined empirical observations and chaos theory on a geometrical basis, thus finding new characteristics regarding the flow properties of pellets and granules that could be relevant for drug developers. Our findings indicate that sphericity and particle size are the most significant factors influencing the flowability of pharmaceutical multiparticular preparations. Furthermore, this study confirms that integrating chaos theory and empirical observations in a time-dependent dynamic model provides a comprehensive understanding of particle flow behavior, pivotal for optimizing manufacturing processes.

The effect of calcium removal from skim milk by ion exchange on the properties of the ultrafiltration retentate.

New processes are needed to produce concentrated milk feedstocks with tailored calcium content, due to the direct link between calcium concentration and final product texture and functionality. Skim milk treatment with cation exchange resin 1% (w/v) or 2% (w/v) prior to ultrafiltration to a volumetric concentration factor (VCF) of 2.5 or 5 successfully decreased the calcium concentration by 20-30% and produced concentrates with solids content at ∼22-24 g 100 g-1 at a VCF of 5. Calcium reduction partially solubilized the casein micelles, increasing the concentration of soluble protein and individual caseins, leading to decreased turbidity but increased protein hydration and hydrophobicity. Decalcification (2% (w/v) resin treatment) reduced thermal stability, significantly decreasing the denaturation temperature of α-lactalbumin and ß-lactoglobulin in the milk by ∼3 °C and ∼1 °C respectively. Filtration was also altered, reducing permeation flux and the gel concentration and increased filtration time. When combined, calcium reduction and filtration altered functional properties including soluble calcium, soluble protein and sedimentable solids, with increased milk protein hydration also contributing to increased viscosity. This study provides a route to produce calcium-reduced milk concentrates with potential for use in retentate-based dairy products with tailored functionality.

Rheological Characteristics of Fe-C-Cr(Ni) Alloys.

The principal objective of this project was to investigate the rheological properties of Fe-C-Cr and Fe-C-Ni-based low-alloy steels using an Anton Paar high-temperature rotational viscometer up to 1550 °C. The emphasis was placed on determining the liquidus temperatures and evaluating the flow and viscosity curves and the temperature dependence of dynamic viscosity. All were studied depending on the change in the content of chromium (0.010-4.863 wt%), nickel (0.001-4.495 wt%), and carbon (0.043-1.563 wt%). It was shown that the dynamic viscosity decreases with increasing nickel content and increases with increasing carbon and chromium content. The experimental data of the flow curves were fitted using the Herschel-Bulkley model with a good agreement between the measured and calculated values. Characterization of the internal structure was performed by SEM and EDX analyses, confirming non-significant changes in the microstructure of the original and remelted samples. The phase composition of the selected samples was also determined using JMatPro 12.0 simulation software (Sente Software Ltd., Guildford, UK).

Consistency of uroflowmetry analysis in children among observers.

AIM: The aim of the study is to compare the intra- and inter-observer interpretations of the same uroflowmetry study at two different times. MATERIALS AND METHODS: Two-hundred children with a voided volume of 50% above the expected bladder capacity were included. All traces were asked to be evaluated by 11 observers two times in a time span of 1 month. These observers consist of pediatric urologists (n = 2), pediatric urology fellows (n = 2), urology residents (n = 5), and certified urodynamics nurses (n = 2). Each uroflowmetry was asked to be assessed for three domains: voided volume (VV), detrusor sphincter dyssynergia (DSD), and flow curve pattern (FCP). RESULTS: Of the 200 patients with a median age of 10 (4-18) years, 128 (64%) were girls and 72 (36%) boys. The maximum flow rate and the median voided volume were found to be 20 (4-61) mL/s and 232 (116-781) mL. The Fleiss' kappa coefficient of VV, DSD, and FCP in the first assessment was 0.510, 0.501, and 0.346. In the second assessment, κ values were 0.530, 0.422, and 0.373. The best-agreed findings were similar at both times. These were found to be low VV (0.602 and 0.626) and intermittent pattern (0.500 and 0.553). Interpreters were found to have a statistically significant difference in agreement with their own interpretation at different times. CONCLUSION: Both inter- and intra-observer reliability of the agreement point out the problem in the standardization of uroflowmetry. Inter- and intra-observer reliability of uroflowmetry interpretation can be increased by defining precise numbers and numerical algorithms.

Investigation of predictive factors for the presence of voiding dysfunction after transvaginal mesh surgery-Can the flow curve shape on uroflowmetry be a predictor?

PURPOSE: This study established the prognostic significance of the uroflowmetry flow curve shape in the presence of voiding dysfunction following transvaginal mesh surgery. METHODS: This is a retrospective study of 439 symptomatic cystocele patients who underwent anterior wall repair with transvaginal mesh surgery. Uroflowmetry and postvoid residual were used to evaluate voiding function both preoperatively and 12 months postoperatively. The patients were divided into two groups: those with and without postoperative voiding dysfunction, and the predictors of postoperative voiding dysfunction were analyzed. The shape of the urine flow curve was analyzed for its influence on the presence of postoperative voiding dysfunction. RESULTS: Thirty-five participants were in the voiding dysfunction group, while 404 were in the nonvoiding dysfunction group. Multivariate analysis was conducted by adding an interrupted-shaped curve to age, Qmax, and postvoid residual, which showed significant differences in univariate analysis, found that age 68 years or older (odds ratio [OR]: 7.68, 95%CI 1.02-58, p = 0.048), postvoid residual ≥110 mL (OR: 2.8, 95%CI 1.25-6.29, p = 0.013) and interrupted-shaped curve (OR: 2.47, 95%CI 1.07-5.69, p = 0.034) were discovered to be independent risk factors for the presence of voiding dysfunction after transvaginal mesh surgery. CONCLUSIONS: Following transvaginal mesh surgery for cystocele, three variables were found to be predictive of voiding dysfunction: the old age, excessive postvoid residual, and an interrupted-shaped flow curve. The uroflowmetry flow curve shape has the potential to be a new predictor of postoperative voiding dysfunction.

Characterization of slurries for lithium-ion battery cathodes by measuring their flow and change in hydrostatic pressure over time and clarification of the relationship between slurry and cathode properties.

HYPOTHESIS: It is important to elucidate the effect of the particle dispersion/aggregation state of electrode slurries on resulting electrodes for the development of superior lithium-ion batteries. Many studies have been conducted to characterize cathode slurries for lithium-ion batteries; however, the particle dispersion state of cathode slurries remains unclear. This study investigates the rheological behavior and the packing ability of the cathode slurries for obtaining a denser electrode with lower electric resistance. EXPERIMENTS: In addition to the conventional flow curve measurement, we measured the changes in the hydrostatic pressure of the slurries with time to evaluate their packing ability. The relationship between the properties of the cathode slurries and those of the as-cast cathodes was also investigated. FINDINGS: It was found that a slurry in which acetylene black powder forms a network structure, with sufficient strength and the ability to rapidly recover after breaking, yields a cathode with comparatively high density and comparatively low volume resistivity. It was also found that the normalized settling time of a cathode slurry determined from its change in hydrostatic pressure over time correlates well with both the density and volume resistivity of a resulting as-cast cathode.

Analysis and Modeling of Stress-Strain Curves in Microalloyed Steels Based on a Dislocation Density Evolution Model.

Microalloyed steels offer a good combination of desirable mechanical properties by fine-tuning grain growth and recrystallization dynamics while keeping the carbon content low for good weldability. In this work, the dislocation density evolution during hot rolling was correlated by materials modeling with flow curves. Single-hit compression tests at different temperatures and strain rates were performed with varying isothermal holding times prior to deformation to achieve different precipitation stages. On the basis of these experimental results, the dislocation density evolution was evaluated using a recently developed semi-empirical state-parameter model implemented in the software MatCalc. The yield stress at the beginning of the deformation σ0, the initial strain hardening rate θ0, and the saturation stress σ∞-as derived from the experimental flow curves and corresponding Kocks plots-were used for the calibration of the model. The applicability for industrial processing of many microalloyed steels was assured by calibration of the model parameters as a function of temperature and strain rate. As a result, it turned out that a single set of empirical equations was sufficient to model all investigated microalloyed steels since the plastic stresses at high temperatures did not depend on the precipitation state.

Study on Hot Deformation Behavior of an Antibacterial 50Cr15MoVCu Tool Steel.

Hot deformation behaviors of an antibacterial 50Cr15MoVCu tool steel were studied. The flow stress curves presented three typical characteristics: (i) a single peak dynamic recrystallization curve, (ii) a monotone incremental work-hardening curve, and (iii) the equilibrium dynamic recovery curve. The flow stress increased with the increase of the deformation rate at each deformation temperature and decreased with the increase of the deformation temperature at the same deformation rate. The thermal activation energy and material constants were Q of 461.6574 kJ/mol, A of 3.42 × 1017, and α of 0.00681 MPa−1, respectively. The high temperature constitutive equation was: Z=ε˙expQ/RT=3.42 × 1017sinh0.0068 × σ5.6807. Based on the processing maps and microstructure evolution, the best hot working process was a deformation temperature of 1050 °C and deformation rate of 0.001 s−1.

Artificial Neural Networks for Predicting Plastic Anisotropy of Sheet Metals Based on Indentation Test.

This paper mainly proposes two kinds of artificial neural network (ANN) models for predicting the plastic anisotropy properties of sheet metal using spherical indentation test, which minimizes measurement time, costs, and simplifies the process of obtaining the anisotropy properties than the conventional tensile test. The proposed ANN models for predicting anisotropic properties can replace the traditional complex dimensionless analysis. Moreover, this paper is not limited to the prediction of yield strength anisotropy but also further accurately predicts the Lankford coefficient in different orientations. We newly construct an FE spherical indentation model, which is suitable for sheet metal in consideration of actual compliance. To obtain a large dataset for training the ANN, the constructed FE model is utilized to simulate pure and alloyed engineering metals with one thousand elastoplastic parameter conditions. We suggest the specific variables of the residual indentation mark as input parameters, also with the indentation load-depth curve. The profile of the residual indentation, including the height and length in different orientations, are used to analyze the anisotropic properties of the material. Experimental validations have been conducted with three different sheet alloys, TRIP1180 steel, zinc alloy, and aluminum alloy 6063-T6, comparing the proposed ANN model and the uniaxial tensile test. In addition, machine vision was used to efficiently analyze the residual indentation marks and automatically measure the indentation profiles in different orientations. The proposed ANN model exhibits remarkable performance in the prediction of the flow curves and Lankford coefficient of different orientations.

Operando observation of concentrated SiO2 suspensions by optical coherent tomography during flow curve measurements: The relationship between polymer dispersant structures and surface interactions.

HYPOTHESIS: Flow curve measurement is commonly used to characterize the flow behavior of concentrated suspensions. However, dynamic changes in the suspension inner microstructures under highly sheared conditions have not been correctly understood even though they strongly affect the measured shear stress. We hypothesize that the real particle dynamics during shearing could be effectively revealed by a systematic investigation that combines macroscopic flow curve measurements with operando microstructural observation employing an optical coherent tomography (OCT) apparatus and surface interaction measurements with the colloidal probe atomic force microscopy (AFM) method. EXPERIMENTS: The model system was spherical SiO2/toluene suspensions stabilized by polyethyleneimine (PEI) partially complexed with different fatty acids. Inner structures of the suspensions during flow curve measurements were observed by the OCT technique. The surface-surface interactions in toluene were analyzed using the colloidal probe AFM method. FINDINGS: Operando OCT observations revealed that during flow curve measurements, the suspensions can have completely different microscopic flow modes depending on the fatty acid species complexed to PEI and the solid concentrations. These microscopic flow modes could not be recognized using the typical flow curve measurements alone. The different flow modes can be explained by surface interactions measured by the colloidal probe AFM method.

Influence of milking units and working vacuum level on the mechanical milking of goats.

The objectives of this study were to evaluate and compare the effect of working vacuum levels (35 and 44 kPa) and liners dimensions (mouthpiece lip diameter and overall length, 20-185 and 22-170 mm) on the main milking characteristics of goats. The results highlight that both the working vacuum level and the liner dimension have influenced the milk flow curve parameters. The maximum variations were found for peak flow rate, which increased significantly with liner dimensions of 20-185 mm at a working vacuum level of 44 kPa as well as average milk flow rate and for plateau phase duration. The incorrect adoption of operative parameters and unsuitable milking machine components, might affect the performance of the mechanical milking and negatively affecting animal productions and welfare.

A Comparative Study on the Hot Deformation Behavior of As-Cast and Twin-Roll Cast Mg-6.8Y-2.5Zn-0.4Zr Alloy.

The Mg-6.8Y-2.5Zn-0.4Zr (WZ73) alloy exhibits different microstructure characteristic after conventional casting compared to the twin-roll cast (TRC) state. Twin-roll casting results in a finer microstructure, where the LPSO phases are more finely distributed and less strongly connected. A transfer of the hot deformation behavior from the as-cast condition to the TRC condition is only possible to a limited extent due to the microstructural differences. Both states show differences in the recrystallization behavior during hot deformation. In the conventional cast state, dynamic recrystallization (DRX) is assumed to be delayed by the occurrence of coarse blocky LPSO phases. Main DRX mechanisms are continuous dynamic recrystallization (CDRX), particle stimulated nucleation (PSN) and twin induced dynamic recrystallization (TDRX). The deformed TRC sample showed pronounced DRX at almost all deformation conditions. Besides the TDRX and the PSN mechanism, kink induced dynamic recrystallization (KDRX) can be observed. Optimum deformation conditions for both states are temperatures from 500 °C to 520 °C, and strain rates ranging from 0.01 s-1 to 0.1 s-1 for the as-cast material as well as a strain rate of 1 s-1 for the TRC material.

Hot Deformation and Dynamic Recrystallisation Behaviour of Twin-Roll Cast Mg-6.8Y-2.5Zn-0.4Zr Magnesium Alloy.

In this work, the deformation behaviour of a twin-roll cast (TRC) Mg-6.8Y-2.5Zn-0.4Zr alloy during plane strain compression was characterised by high-temperature testing. Based on the experimental data, the values of strain-rate sensitivity, the efficiency of power dissipation and the instability parameter were investigated under the conditions of various hot deformation parameters. In contrast to conventionally cast material, no lamellae of the LPSO (long period stacking ordered) phase were precipitated in the magnesium matrix after TRC. The precipitation of fine lamellar LPSO phases only occurred during cooling to forming temperature after the heat treatment. Dynamic recrystallization (DRX) hardly occurred during deformation at temperatures between 350 °C and 400 °C. This can be attributed to the precipitation of the lamellar LSPO phases, which contribute to retardation of the DRX process. At higher deformation temperatures and strain rates DRX is pronounced and the twin-induced (TRDX) as well as continuous dynamic recrystallization could be identified as the dominant softening mechanisms. The processing maps were established by superimposing the instability map over the power dissipation map, this being associated with microstructural evolution analysis in the hot deformation processes. Two instability zones could be recognised for the twin-roll cast and heat-treated Mg-6.8Y-2.5Zn-0.4Zr alloy: (1) 350 °C to 460 °C and 0.01 s-1 to 0.3 s-1 and (2) 485 °C to 525 °C and 2.5 s-1 to 10 s-1, where deformation is not favourable.

Go with the flow-clinical importance of flow curves during mechanical ventilation: A narrative review.

Most clinicians pay attention to tidal volume and airway pressures and their curves during mechanical ventilation. On the other hand, inspiratory-expiratory flow curves also provide a plethora of information, but much less attention is paid to them. Flow curves chronologically show the velocity and direction of inspiration and expiration and are influenced by the respiratory mechanics, the patient's effort, and the mode of ventilation and its settings. When the ventilator setting does not synchronize with the patient's respiratory pattern, the patient can easily have worsening breathing effort, patient-ventilator asynchrony, which can lead to prolonged ventilator support or lung injury. The information provided by the flow curves during mechanical ventilation, such as respiratory mechanics, the patient's effort, and patient-ventilator interactions, are very helpful when adjusting the ventilator setting. If clinicians can monitor and assess the flow curves information appropriately, it can be a useful diagnostic and therapeutic tool at the bedside. There may be association between inspiratory effort and flow, and this may further guide us, especially in the weaning process and when patients are not synchronizing with the ventilator. In this review, we try to gather information about "flow" that is scattered around in the literature and textbooks in one place. We will summarize the different flow waveforms utilized in commonly used ventilator modes with their advantages and disadvantages, information gained by the flow curves (i.e., flow-time, flow-volume, and flow-pressure), how to detect and manage asynchronies, and some ideas for future uses. Flow waveforms shapes and patterns are very beneficial for the management of patients undergoing mechanical ventilatory support. Attention to those waveforms can potentially improve patient outcomes. Clinicians should be familiar with this information and how to act upon them.

Impact of methodological artifact on digested sludge flow curve measurement.

Inconsistent experimental procedures have been used to characterize sludge rheology in literature. This often has resulted in proposing different rheological models for sludge as well as non-comparable data. Any collected rheological data needs to be interpreted considering the methodology used for its collection because otherwise they cannot be used by engineers for design and troubleshooting. This paper intends to shed light on the influential parameters during data collection procedure to produce a reliable and reproducible data. This paper systematically investigates the impact of different geometries, preshear, equilibrium, rest and storage time on flow curve measurement for digested sludge in the range of 2.3 to 6% total solid and recommends a reliable procedure for reproducible sludge flow curve measurements. While the magnitude of impacts is different, we found all factors are significantly dependent on the sludge solid concentration. Besides, the method of the development of the protocol can be utilized to develop appropriate protocols for rheological characterization of any other sludge. The customization highlights are:•Selecting the geometry according to the sludge solid concentration.•Allocating an equilibrium time at each point of flow curve according to the sludge solid concentration.•Flow curve data requires to visually inspected for instabilities.

Viscosity of API/fatty acid suspensions: Pitfalls during analysis.

This article describes how to obtain reliable data during rheological analysis of active pharmaceutical ingredient/fatty acid suspensions. These materials are specifically used for prilling, an innovative pharmaceutical technique for the production of a multiparticulate dosage form. Nevertheless, presented guidelines are applicable for a wide range of pharmaceutical suspensions. Reliable rheological results can only be obtained when being aware of artefacts, such as a non-continuous medium, sedimentation, apparent wall slip and protrusion flow. To comply with the continuum hypothesis at high phase volumes (≥25% w/w), the required gap-to-particle-size ratio may be larger than the generally accepted 10:1 ratio. Reproducible flow curves that are not disturbed by sedimentation during sample analysis can be obtained faster by varying the shear rate stepwise from high to low values. While apparent wall slip (at low shear rates) can be prevented via serrated instead of smooth plates, protrusion flow (at high shear rates) during measurements with serrated plates results in non-reliable data. Therefore, in general, high viscous suspensions with yield stress can be analysed with serrated plates, while low viscous suspensions without yield stress should be analysed with geometries having smooth surfaces. By following these guidelines, accurate rheological properties of pharmaceutical suspensions can be obtained.

Microstructure and Hot Deformation Behavior of Twin Roll Cast Mg-2Zn-1Al-0.3Ca Alloy.

In the present work, the microstructure, texture, mechanical properties as well as hot deformation behavior of a Mg-2Zn-1Al-0.3Ca sheet manufactured by twin roll casting were investigated. The twin roll cast state reveals a dendritic microstructure with intermetallic compounds predominantly located in the interdendritic areas. The twin roll cast samples were annealed at 420 °C for 2 h followed by plane strain compression tests in order to study the hardening and softening behavior. Annealing treatment leads to the formation of a grain structure, consisting of equiaxed grains with an average diameter of approximately 19 µm. The twin roll cast state reveals a typical basal texture and the annealed state shows a weakened texture, by spreading basal poles along the transverse direction. The twin roll cast Mg-2Zn-1Al-0.3Ca alloy offers a good ultimate tensile strength of 240 MPa. The course of the flow curves indicate that dynamic recrystallization occurs during hot deformation. For the validity range from 250 °C to 450 °C as well as equivalent logarithmic strain rates from 0.01 s-1 to 10 s-1 calculated model coefficients are shown. The average activation energy for plastic flow of the twin roll cast and annealed Mg-2Zn-1Al-0.3Ca alloy amounts to 180.5 kJ/mol. The processing map reveals one domain with flow instability at temperatures above 370 °C and strain rates ranging from 3 s-1 to 10 s-1. Under these forming conditions, intergranular cracks arose and grew along the grain boundaries.

Effect of bladder overdistention on uroflowmetry and post-void residual urine in children with enuresis / 中华实用儿科临床杂志

Objective@#To explore the effect of bladder overdistention on uroflowmetry and post-void residual urine(PVR)in children with primary nocturnal enuresis (PNE).@*Methods@#A total of 136 children with PNE from March 2015 to June 2018 at Department of Pediatric Urodynamic Center, the First Affiliated Hospital of Zhengzhou University were enrolled, aged 5-14 years, with mean age of (7.96±2.48) years old.Uroflowmetry and PVR measurement were performed in the condition of over and no urinary distention, respectively.According to the initial urinary voided volume (VV), the children were divided into 3 groups, 25 mL≤ VV<50 mL(group 1), 50 mL≤VV<100 mL(group 2), and VV≥100 mL(group 3). The VV, maximum flow rate (Qmax), average flow rate (Qave), urine flow time, and PVR were compared interms of condition between the groups.Different types of flow curve were analyzed simultaneously.@*Results@#In the condition of bladder over distention, the VV, Qmax, Qave, urinary flow time and PVR of children were higher than those with no overdistention[group 1: (168.25±103.23) mL vs.(34.04±7.03) mL, (17.76±11.13)mL/s vs.(8.23±2.72) mL/s, (9.56±4.13) mL/s vs.(4.30±1.55) mL/s, (20.24±15.13) s vs.(8.64±4.27) s, (3.90±3.55) mL vs.(1.50±2.55) mL; group 2: (168.65±80.66) mL vs.(68.04±15.13) mL, (16.41±5.18) mL/s vs.(14.61±5.29) mL/s, (9.86±3.56) mL/s vs.(8.14±2.29) mL/s, (18.75±10.73) s vs.(9.41±3.47) s, (5.98±8.59) mL vs.(2.77±6.41) mL; group 3: (280.24±102.00) mL vs.(181.50±66.22) mL, (22.73±8.21) mL/s vs.(20.42±6.25) mL/s, (12.57±3.68) mL/s vs.(11.00±3.22) mL/s, (23.46±10.65) s vs.(17.01±6.90) s, (3.78±6.26) mL vs.(2.09±3.21) mL], and the differences were all significant(all P<0.05). Excluding physiological pseudomorphism, urinary flow curves of 114 children with initial urinary intention and excessive voiding were obtained.The incidence of Staccato urinary flow curve was significantly higher than that with no distention [6.14%(7/114 cases) vs.21.93%(25/114 cases), χ2=14.45, P<0.05].@*Conclusions@#Bladder overdistention induced significant influence on the uroflowmetry and PVR.