Test Variables Research Articles

Oat polar lipids and sunflower lecithin similarly improve cardiometabolic risk markers and appetite controlling hormone responses after breakfast and a subsequent lunch. A randomized crossover study in healthy adults

IntroductionThe alarming global increase in lifestyle-related disorders such as obesity and type 2 diabetes mellitus (T2DM) has increased during the last several decades. Poor dietary choices significantly contribute to this increase and prevention measures are urgently needed. Dietary intake of bioactive compounds found in foods are linked to a decrease likelihood of these disorders. For this purpose, a randomized crossover meal study was performed to compare the postprandial metabolic effects of lecithin and oat polar lipids in healthy subjects.Materials and methodsEighteen young healthy subjects ingested test meals enriched with lecithin, oat polar lipids (PLs) or rapeseed oil. There were four test meals (i) 15 g oat polar lipids: OPL, (ii) 18 g sunflower lecithin (of which 15 g were polar lipids): LPL, (iii) 18 g rapeseed oil: RSO, and (iv) reference white wheat bread: WWB. Lipid-enriched test meals contained equivalent amounts of total fat (18 g), and all breakfast meals contained 50 g available carbohydrates. The meals were served as breakfast followed by a standardised lunch (white wheat bread and meat balls) after 3.5 h. Test variables were measured at fasting and repeatedly during 5.5 h after ingestion of the breakfast.ResultsOur study demonstrated that both LPL and OPL had beneficial effects on postprandial glucose and insulin responses, and appetite regulating gut hormones, as compared to RSO and WWB. Significant increase in GLP-1, GIP, and PYY concentrations were seen after consuming breakfast meals with LPL and OPL, and ghrelin concentration was reduced compared to meals with RSO and WWB (p < 0.05). Furthermore, triglycerides (TG) concentration was significantly reduced after OPL compared to RSO (p < 0.05). Our data show that there were no significant variations in glycaemic and insulin responses, TG, and gut hormone concentrations between LPL and OPL during breakfast (0–210 min) or over the whole study period (0–330 min).ConclusionOur study revealed that the consumption of both lecithin and oat PLs included in breakfast meal may similarly enhance postprandial glucose tolerance, reduce TG, and enhance the secretion of incretins and appetite regulating hormones in healthy young adults.Clinical trial registrationClinicalTrials.gov, identifier NCT05139355.

Utilization finite element and machine learning methods to investigation the axial compressive behavior of elliptical FRP-confined concrete columns

Nowadays, elliptical sections are among the geometric shapes that are becoming more and more popular in the architecture world. Finite element analysis (FEA) software, such as ABAQUS, is used to simulate elliptical concrete columns confined with fiber reinforced polymer (FRP) jackets based on experimental data published in the literature. The validity of the finite element modeling (FEM) approach was confirmed by comparing it to experimental data obtained from 45 specimens in existing studies, demonstrating a favorable agreement. Additionally, a parametric study was also carried out, which included simulating 40 more specimens, resulting in a total of 85 specimens for analysis. The effect of various test variables such as sectional aspect ratio, the amount of FRP layers, and concrete strength on the elliptical column’s behavior is investigated. The axial compressive strength is predicted using current models from the literature. The outcomes revealed that the higher unconfined concrete strength decreased FRP confinement efficacy. Insufficient confinement with post-peak softening is more likely in FRP-confined high strength concrete columns, especially if the confinement was not stiff enough. Also, by adding more FRP layers, the stress and strain capabilities of elliptical concrete columns confined with FRP composites are improved. Physical experiments require a significant investment of time and resources, but they can produce valuable results. Finite element analysis, on the other hand, depends heavily on the modeler's competence and can minimize the number of experiments required by employing computer simulation, but it also requires high computer settings. In recent years, there has been a major advancement in the usage of machine learning (ML) algorithms in the applications of FRP composites with different concrete components. Taking this into consideration, this investigation is extended to estimate the compressive strength of elliptical FRP-confined columns using four tree-based ML algorithms including Decision Tree, Random Forest, Gradient Boosting and XGBoost. The XGBoost model achieved the highest predictive accuracy with the R2 values of 0.95 for both the compressive strength and axial strain targets.

Left atrial strain differences between hypertensive and sarcomeric left ventricular hypertrophy: a sign of sarcomeric auricular myopathy?

Abstract Introduction In clinical practice, left ventricular (LV) hypertrophy is a common finding that can be caused by physiologic or pathologic conditions. An etiologic diagnosis is extremely important because it may change the prognosis and management of the patient and his family. Left atrial (LA) dysfunction is common due to diastolic dysfunction but, in patients with sarcomeric LV hypertrophy, primary cardiomyopathy disease could also be present. Purpose To evaluate if there are differences in LA function between arterial hypertension (HT) and hypertrophic cardiomyopathy (HCM) patients. Methods 73 patients with HCM (according to ESC guidelines criteria) and 82 patients with HT (under treatment with ≥1 hypertensive drug for ≥3 months) and ≥13mm of LV hypertrophy underwent an echocardiography to assess LA function with strain analysis and LV diastolic function. Continuous normally distributed variables were compared with T-student test and categoric variables with square-chi or exact Fisher test if required, accepting as significant a p-value <0.05. Results Globally, HCM patients showed thicker LV walls and larger LA indexed volumes (18.7±4.7 vs. 13.3±0,8 mm and 44.9±20.7 vs. 30.7±8.8 ml/m2, p<0.000 for both). Also, HCM patients presented diastolic dysfunction and atrial fibrillation history in a higher frequency (31 vs. 7.6% and 16.4% vs. 0%, p<0.000 for both). LA strain was significantly lower in HCM patients as compared to the HT group (LA contractile 11.5±5.8 vs. 17.2±4.4, p<0.000; LA conduit 12.2±5.4 vs. 13.3±3.8, p=0.041; and LA reservoir 23.9±8.7 vs. 31.1±5.9, p<0.000). In the subgroup of patients with moderate-severe LV hypertrophy (<17mm) and no significant mitral regurgitation (n=103; HCM=21, HT=82), LA contractile strain remained lower in HCM as compared to HT patients (13.2±4.8% vs. 17.2±4.4%, p<0.000) (figure 1); without differences in diastolic dysfunction, LA volumes, significant mitral regurgitation or atrial fibrillation history. Conclusions Our results show that LA strain is more impaired in HCM patients as compared to HT patients. Specifically, contractile LA strain remained lower even in those patients with moderate-severe LV hypertrophy, despite having similar LV diastolic function, LA indexed volumes, significant mitral regurgitation, or atrial fibrillation history. These findings could be caused by HCM involvement of the LA myocytes. In the context of moderate-severe hypertrophy of unknown origin with non-significant mitral regurgitation, the detection of abnormally reduced LA strain could indicate the presence of an HCM.Figure 1

Nutritional management, skipping breakfast, glycemic control, and cardiovascular risk on type 2 diabetes mellitus

Abstract Background Meal timing is an emerging field that investigates the influence of eating patterns on circadian rhythm and general health. There is still disagreement in the literature as to whether eating windows could impact weight gain and biochemical markers. Purpose 1- Evaluate the impact of nutritional interventions on weight, body mass index (BMI), waist circumference (WC), fasting blood glucose (FG), glycated hemoglobin (HbA1c), LDL cholesterol (LDL-C), HDL cholesterol (HDL-C), triglycerides, systolic blood pressure (SBP), and diastolic blood pressure (DBP), between 0th and 12th month in Type 2 Diabetes Mellitus (T2D); 2-Observe breakfast skipping and sleep disorders, and also analyze the influence of these data with possible changes in anthropometric and biochemical markers. Methods This experimental and observational study recruited 44 participants with T2D. The assessments were carried out in October 2022 and 2023. The nutritional assessment consisted of prescribing a personalized eating plan (Mediterranean diet and DASH). Statistical analysis: For the variables "breakfast habits", "nocturnal awakenings", and "sleep duration", the numbers of participants were converted into percentages of the total number of individuals. Parametric variables were compared using the paired t-test and non-parametric variables were compared by the Wilcoxon test. To evaluate the influence of the habit of eating breakfast and sleep disorders on quantitative variables, variations were calculated between the 0th and 12th month between participants who had or did not have the habit of eating breakfast and had or did not have sleep disorders. Parametric variables were compared using the unpaired t test and non-parametric variables using the Mann-Whitney test. Parametric data were presented as mean ± standard deviation and non-parametric data as median ± interquartile range, both accompanied by the dispersion of all repetitions. α<0.05 and P<0.05 were adopted. Results Significant reductions were found between the 0th and 12th month of FG, HbA1c, LDL-C, triglycerides, SBP, DBP, BMI, WC, and weight (p<0.0001). Regarding breakfast habits, in the 1st month, 77.3% of participants skipped this meal, reducing to 13.6% in the 12th month. For sleep duration, in the 1st month, 90.9% of participants slept less than 6 hours, reducing to 40.9% in the 12th month. For nocturnal awakenings, 70.5% of participants had at least 1 awakening in the 1st month, reducing to 54.5% in the 12th month. For influence analysis, no significant differences were found between changes in FG, HbA1c, LDL-C, triglycerides, SBP, DBP, BMI, WC, and weight on breakfast habit or sleep disorders, except for HDL-C and sleep disorders (p<0.005). Conclusion Nutritional management improved biochemical markers, reduced anthropometric data, regulated the eating window, reduced nocturnal awakenings, and optimized sleep duration in patients with T2D.

Recent cardiac rehabilitation and its impact on cardiopulmonary exercise test variables in Brazilian cardiac transplant recipients

Abstract Introduction Heart transplantation (HTx) is an option for restoring the functional capacity of individuals with end-stage heart failure (HF). Cardiac rehabilitation (CR) plays an important role in improving variables related to cardiopulmonary exercise testing (CPET) in post-HTx patients. Purpose To evaluate whether CR is effective in improving CPET variables in Brazilian patients post-recent HTx compared to a Control Group (CG). Methods Retrospective comparative study composed of two groups: CR group (CRG) and CG. These recent HTx patients (aged 14 to 73 years) initiated CR within 150 days and were recruited from an HTx outpatient clinic at a south Brazilian public university hospital between 2014 and 2023. CPET was performed at three different times: pre-HTx (Time 01), post-recent HTx (Time 02), and post-CR or post-follow-up for CG (Time 03). This study was approved by the Institutional Review Board (protocol No. 20180651). Statistical analysis used Generalized Estimating Equations with alpha ≤ 0.05, and the mean difference (MD) data were presented along with 95% confidence interval (CI). Results CRG (n=18) had a mean age of 47.3±15.6 years and CG (n=11) 48.6±12.5 years (P=0.81). The mean time to start CRG was 62.2±9.6 days (minimum: 21; maximum: 147). There was an interaction for the Group*Time factor for the following CPET variables: VO2peak (P=0.039); VEmax (P=0.009); VO2 on second ventilatory threshold (P<0.001); HR on VT2 (P=0.030) and T½ (P=0.002). The main results are summarized in Table 1. We highlight that there was a difference in the comparison between groups at Time 03 for the variable VO2peak: MD: 5.16 ± 1.95 (95% CI: 1.3 to 9.0; P = 0.008), favorable to CRG. Conclusion Early CR after very recent HTx significantly increase peak VO2peak, VEmax, T½ and VO2 and HR at the VT2 compared to the control group (CG).

Treatment of equine keratomycosis, part 1: selection of appropriate therapy based on clinical presentation and diagnostic testing improves clinical outcomes.

To determine clinical outcome, treatment costs, and hospitalization duration in horses treated for keratomycosis and identify ophthalmic examination and diagnostic results associated with these outcomes. This was a retrospective study of 126 equine keratomycosis cases between 2004 and 2020 with fungal infection confirmed on cytology, culture, and/or histopathology and a minimum of 1-month follow-up. Details of the ophthalmic examination, diagnostic test results, and treatment and cost outcomes were recorded. Outcomes of interest were analyzed by treatment type. The relationship of patient and diagnostic test variables to the outcomes of interest was determined via logistic and linear regression models. Globe retention and positive visual outcome occurred in 82.5% and 78.9% of medically and 88.4% and 85.5% of surgically treated cases, respectively. While not statistically significant, there were more positive clinical outcomes with surgery; in recent years, the globe and vision were preserved in 94.7% of cases following penetrating keratoplasty. The choice to pursue surgery was related to lesion depth. Medical treatment was associated with statistically shorter hospitalization times and lower total and hospitalization invoices compared to all surgical treatments. Diagnosis of stromal abscess was associated with higher total invoice and longer hospitalization times compared to ulcerative keratomycosis, although clinical outcomes were similar. Overall positive clinical outcomes were achieved despite the severity of the disease in many cases, highlighting the need for appropriate treatment selection based on clinical presentation. Expanding knowledge of clinical decision-making, treatment options, and associated clinical and financial outcomes may further improve outcomes for equine keratomycosis patients.

Is there value in the routine inclusion of chest computed tomography for patients with gastrointestinal stromal tumor?

PurposeNational Comprehensive Cancer Network guidelines suggest chest CT when gastrointestinal stromal tumors are larger than 2 cm. We evaluate the value of screening the chest region during initial and follow-up CT. MethodSingle institution retrospective analysis of GIST cancer registry for patients diagnosed between May 2010 and November 2019 with tumor > 2 cm. We collected the patient demographics and clinical data; reviewed all CT scans of the chest region and recorded the lung nodules. Patients were grouped into lung nodule group and non-nodule group. Categorical variables were compared with the Chi square test and continuous variables with the Mann-Whitney U test. The survival probability was determined from Kaplan-Meier survival analysis and log-rank test for comparing differences. ResultsThe final cohort included 382 patients (median age 61 years-old [interquartile range: 52–71]) and grouped into non-nodule group (n = 284) and lung nodule group (n = 98). The frequency of the CT scan was more in lung nodule group (8 [5–12]) than in non-nodule group (4 [2–9], p < 0.001). The lung nodule group had more CT including the chest region (6 [3–10] vs 3 [1–7], p < 0.001). In progressive lung nodules (8/98 [8 %]), only one patient had confirmed lung metastasis from GIST (1/382 [3 %]). There was no difference in overall survival between nodule groups (p = 0.12). ConclusionsGIST patients with tumors larger than 2 cm have extremely low risk for lung metastasis. Routine inclusion of chest CT scan in staging and follow up is unnecessary.

Effects of Supplementation of Different Antioxidants to Cryopreservation Extender on the Post-Thaw Quality of Rooster Semen-A Meta-Analysis.

The standardization of the semen cryopreservation technique could be an effective tool in poultry for the conservation of genetic resources. During this process, the production of reactive oxygen species increases, leading to oxidative stress that causes damage to the spermatozoa. To reduce this effect, the addition of exogenous antioxidants in the cryopreservation diluent has been reported to be effective. Multiple antioxidants such as catalase, vitamin E, cysteamine, ergothioneine, and serine have been studied in roosters. Therefore, the present investigation aims to perform a meta-analysis to determine if the use of the aforementioned antioxidants added to the cryopreservation extender produces an improvement in semen quality parameters in roosters after thawing. After collecting the data, a discriminant canonical analysis was performed to determine which of the selected semen quality traits provided the most information, with hypo-osmotic swelling test (HOST), viability, and total motility variables showing the highest discriminatory power. However, according to the descriptive statistics, catalase and serine are the antioxidants that improve a greater number of seminal quality parameters, and since catalase gives the most favorable results for most of the discriminating variables, it could be the antioxidant of choice.

Comparison of single shot and multishot diffusion-weighted imaging in 5-T magnetic resonance imaging for brain disease diagnosis.

Diffusion-weighted imaging (DWI) with single-shot echo-planar imaging (ssEPI) is a valuable tool for detecting acute brain lesions but does suffer from image distortions. Multishot echo-planar imaging (msEPI) is a technique for reducing such distortions. This study aimed to compare the image quality and diagnostic efficacy of ssEPI- and msEPI-DWI at 5.0 T for brain disease detection. This study retrospectively reviewed images of 107 consecutive patients with suspected brain diseases who underwent ssEPI- and msEPI-DWI at 5.0 T at the First Affiliated Hospital of University of Science and Technology of China from August 2023 to September 2023. Two radiologists independently graded image quality and measured the image distortion. Signal-to-noise ratio, contrast-to-noise ratio, and apparent diffusion coefficient (ADC) were calculated and compared between ssEPI- and msEPI-DWI. Image quality scores were compared using the Wilcoxon test and other continuous variables by the paired t-test. The diagnostic accuracy of ADC values in distinguishing lesions from normal-appearing tissues was measured with the area under the curve (AUC). Image quality evaluation and distortion analysis revealed that msEPI-DWI significantly outperformed ssEPI-DWI (two-sided P<0.001). No significant difference was observed in signal-to-noise ratio, contrast-to-noise ratio, or ADC values between msEPI- and ssEPI-DWI (two-sided P≥0.601). The ADC values of msEPI- and ssEPI-DWI showed strong correlations for both lesions (r=0.97) and contralateral normal tissues (r=0.91) (two-sided P<0.001). Compared to those of the contralateral white matter, ADC values of low-grade gliomas (LGGs) were significantly higher [ssEPI-DWI: 1,119.9±273.1 vs. 805.1±73.9; msEPI-DWI: 1,196.2±355.6 vs. 757.3±98.0 (unit: ×10-6 mm2/s)], while the ADC values of acute cerebral infarction (ACI) lesions were significantly lower [ssEPI-DWI: 603.9±273.2 vs. 888.9±212.0; msEPI-DWI: 538.0±281.2 vs. 905.0±188.9 (unit: ×10-6 mm2/s)] (two-sided P≤0.003). The AUCs for detecting LGGs were excellent for both ssEPI-DWI [AUC =0.934; 95% confidence interval (CI): 0.84-1.00] and msEPI-DWI (AUC =0.944; 95% CI: 0.86-1.00) (two-sided P<0.001; two-sided DeLong test: P=0.833). As compared to ssEPI-DWI, msEPI-DWI, when performed at 5.0 T, demonstrated superior image quality and less anatomical distortion in a wide spectrum of brain diseases and showed promising diagnostic performance for LGGs and ACI. In the future, msEPI-DWI at 5.0 T could become clinically routine in the diagnosis and grading of brain disorders.

Pullout behavior of recycled macro fibers embedded in ultra-high performance seawater sea-sand concrete

Recently, an eco-friendly ultra-high performance concrete (UHPC) has been developed using seawater, sea-sand (UHPSSC) and the recycled macro fiber (REF) processed from waste wind turbines, which could be easily available in remote islands and address the corrosion issue of concrete structures with steel reinforcements. The interface bond of the UHPSSC/macro fiber are lack of investigation and a significant factor influencing the tensile characteristics of macro fiber reinforced UHPSSC. In the present study, the pullout test of the single macro fiber was conducted to investigate the average bond behavior of such interface. The test variables included the macro fiber width (4, 6, and 8 mm), the embedded length (5, 10, and 15 mm), and the type of matrix. Then, the local bond-slip relationship at the fiber/UHPSSC interface was obtained by finite element analysis (FEA) to provide a more precise display of interface bond mechanisms. The results revealed that the bond of UHPSSC/macro fiber was stronger with increased fiber embedded length and width due to the greater frictional interactions and better overall integrity. Additionally, the FEA method proposed here to obtain the local bond-slip relationship was reliable and effective. This study can serve as a basis for further research on the tensile properties of UHPSSC reinforced with macro fibers.

Combined Bending-Torsion and Compression-Bending-Torsion Behaviours of Reinforced Concrete-Filled Thin-Walled Corrugated Steel Tubes

Reinforced concrete-filled thin-walled galvanized corrugated steel tube (RCFCST) is a novel composite member that has application potential in extremely corrosive environments and seismic activity regions. A series of preliminary works have been conducted on its compressive, flexural, shear, and torsional behaviour. However, the combined loading condition is almost inevitable in practice. The correlations between the flexural and torsional behaviour of RCFCSTs are unique due to the special spiral corrugated profile, which is unclear and needs to be addressed. This paper, therefore, presents an experimental investigation of the RCFCST under combined bending-torsion and compression-bending-torsion loads, encompassing the main test variables of torsion-to-bending ratios, torsional directions, and axial compression ratios. The loading set-up and instruments have been introduced in detail. The failure modes, lateral load versus lateral displacement curves, bending moment versus flexural lateral displacement curves, torsion moment versus torsional angle curves, and strain distributions are carefully addressed. The working mechanisms of the RCFCST under combined loads are discussed, with a particular explanation of the dependent behaviour on the torsion-to-bending ratios and torsional directions. The applicability of the existing design methods for the bearing capacity of RCFCST specimens under combined loads is examined carefully, with specific design suggestions proposed.

Optimizing the detection of N-nitrosamine mutagenicity in the Ames test

Accurately determining the mutagenicity of small-molecule N-nitrosamine drug impurities and nitrosamine drug substance-related impurities (NDSRIs) is critical to identifying mutagenic and cancer hazards. In the current study we have evaluated several approaches for enhancing assay sensitivity for evaluating the mutagenicity of N-nitrosamines in the bacterial reverse mutagenicity (Ames) test. Preincubation assays were conducted using five activation conditions: no exogenous metabolic activation and metabolic activation mixes employing both 10% and 30% liver S9 from hamsters and rats pretreated with inducers of enzymatic activity. In addition, preincubations were conducted for both 60 min and 30 min. These test variables were evaluated by testing 12 small-molecule N-nitrosamines and 17 NDSRIs for mutagenicity in Salmonella typhimurium tester strains TA98, TA100, TA1535, and TA1537, and Escherichia coli strain WP2 uvrA (pKM101). Eighteen of the 29 N-nitrosamine test substances tested positive under one or more of the testing conditions and all 18 positives could be detected by using tester strains TA1535 and WP2 uvrA (pKM101), preincubations of 30 min, and S9 mixes containing 30% hamster liver S9. In general, the conditions under which NDSRIs were mutagenic were similar to those found for small-molecule N-nitrosamines.

Simple Mobility Tests Predict Use of Assistive Devices in Older Adults.

Assistive devices (ADs) for ambulation are commonly provided to improve safety and independence in older adults. Despite the common use of these devices, there are no standard prescribing guidelines, and non-health care providers, including caregivers and family members, often make decisions about the need for ADs. Identifying factors or a single screening test associated with AD use would benefit clinicians and non-health care caregivers in making decisions to adopt an AD for patients, clients, and family members. The purpose of this cross-sectional study was to identify the test that best predicts ADs for ambulation and non-AD use among community-dwelling individuals. Eighty-five older adults (81.6 ± 8.2 years old) who underwent outpatient physical therapy participated in this study. They participated in a series of tests, including the Timed Up and Go, handgrip and quadriceps strength, the 30-second chair-rise test, the 5-m fast gait speed, the Functional Independence Measure, the locomotive syndrome tests (stand-up test, 2-step test [2ST], and the Locomo-5 Checklist), and numeric pain scales. Mann-Whitney U tests were used to identify differences between those who did and did not use an AD for ambulation. Logistic regression analyses were used to examine which test best predicted AD use. 80% of participants (n = 68) used an AD for ambulation. There were significant differences in all test variables between users and nonusers (P = .033 to P < .001), except for quadriceps strength, age, and pain (all P > .05). Only the 2ST was a significant predictor of AD use, with a cutoff distance of the toe-to-toe stride shorter than 93% of body height (sensitivity: 72%, and specificity: 82%, P = .048). Simple functional measures differed between those who did and did not use ADs for ambulation; however, only the 2ST predicted AD status. Individuals who cannot step 93% of their body height may be appropriate for an AD. If comprehensive clinical evaluations are not available to make decisions about AD use, the 2ST can be used to make clinical recommendations for an AD for ambulation.

Experimental study on the compressive behavior of UHPC filled stainless steel tubes subjected to monotonic and cyclic loading

Ultra-High Performance Concrete Filled Stainless Steel Tubular (UHPCFSST) column is a novel type of composite columns appealing to be adopted in corrosive and marine environment. To explore the axial performance of UHPCFSST columns, this paper initiates an experimental program containing 14 UHPCFSST columns subjected to either monotonic or cyclical axial compressive loading. The test variables in this program mainly include the column dimension, tube thickness and the loading schemes. Based on the test results, the damage evolution process, ultimate failure mode, load-deformation response and the typical mechanical performance indexes inclusive of loading-carrying capacity, stiffness degradation, as well as ductility coefficient are thoroughly examined. After that, theoretical analysis is carried out to explore the interaction behavior between UHPC and stainless-steel tube and hence judge the degree of confinement effect. To assess the applicability of the code equations stipulated in current international design guidelines and the empirical formulas proposed by other researchers, a small-scale dataset containing 41 UHPCFSST columns was compiled to make comparison of axial capacity between test results and analytical predictions. In view of the limited accuracy or the burdensome calculation process, a new formula considering actual loading carrying mechanism was proposed to calculate the axial capacity of UHPCFSST columns, which exhibits enhanced accuracy and efficiency than the current formulas.

Structural behavior of S-UHPC-S composite wall strips with waved tie bars: Experiment, simulation, and design

In this paper, novel steel waved tie bar shear connectors were developed in conjunction with ultra-high-performance-concrete (UHPC) core to obtain lightweight, high-strength, and easy-construction steel-UHPC-Steel (S-UHPC-S) composite structures. To study the structural behavior of S-UHPC-S composite wall panels with waved tie bars subjected to out-of-plane loads, seven 1/2 scaled S-UHPC-S composite beams were extracted and tested under three-point bending. Test variables included longitudinal and transverse reinforcement ratios, and shear span ratio. Experimental results indicated that S-UHPC-S composite beams failed in flexure mode under the shear span ratios of 2.5 and 3.5 and in flexure-shear mode under the shear span ratio of 1.5. Increasing the longitudinal reinforcement ratio from 1.0 % to 1.5 % and 2.0 % increased the peak load capacity of the S-UHPC-S composite beams by 16.5 % and 43.6 %, respectively, but increasing the transverse reinforcement ratio had a marginal effect on the load resistance because the S-UHPC-S composite beams were dominated by flexure or flexure-shear failure mode. Full-scale models were built with the finite element (FE) software LS-DYNA. After being validated with the test results, the FE model is used to conduct extended studies. Numerical results indicate that the contribution proportion of each component to the bending moment capacity of the S-UHPC-S composite beam can be sorted in a descending order, namely, steel faceplates > UHPC > ribs > tie bars. A method was proposed to predict the failure mode of the S-UHPC-S composite beams in accordance with shear span ratios and mechanical reinforcement ratios. Finally, computation methods for flexure strength and the maximum stud spacing were developed.

An investigation on the wear properties of the photocurable components produced by additive manufacturing for dentistry applications: Combined influences of UV exposure time, building direction, and sliding loads

AbstractAdditive manufacturing (AM) of polymers is a highly versatile technology that can be applied to many independent sectors like automotive, aviation, medicine, and dentistry. Since it has great potential for rapid prototyping, clean‐process concepts, and the ability to produce complex shapes, the layer‐by‐layer printing method is one of the most promising alternatives for future industrial production efforts. In that sense, different from the previous studies, this work aims to elucidate the friction and wear properties of the special dental samples manufactured via photopolymerization‐based AM technology according to both for printing parameters, and dry sliding test variables. Also, this is the first initiation to examine the combined influences of the UV exposure time, building direction, and sliding force on the surface roughness, hardness, friction coefficient, wear rate, and main plastic damage mechanism of the printed samples. The results showed that the maximum average hardness value was detected as 89.8 Shore D for vertically built samples printed with 8 s exposure time. In addition, vertically printed samples exhibited better wear resistance than the horizontal samples and the rising exposure time generally affected affirmatively the hardness levels of the samples. The lowest volume loss of 78 mm3 belonged to the vertical sample at 5 N. Further, increasing test force levels caused a decrease in the friction coefficient results and triggered the volume loss increase in the samples. Among all samples, the calculated friction coefficient values changed between 0.3 and 0.87. On the other side, scanning electron microscopy (SEM), and energy‐dispersive spectroscopy (EDS) analyses pointed out that ascending exposure times led to the altering contact surface matchings determining the final volume loss outcomes.Highlights To obtain better surface quality, vertical printing was a useful option. Horizontally printed samples exhibited higher friction coefficients. Curing time positively impacted the wear resistance for both orientations. Grooves and debris parts were observed on surfaces with low exposure times.

Establishing minimal clinically important differences for the quality of life scale QLICD-SLE for patients with systemic lupus erythematosus based on ROC curve

The minimal clinically important difference (MCID) is an important concept with big appeal in a field struggling to interpret quality of life (QOL) and other patient-reported outcomes (PRO), is also a bridge between statistics and clinical medicine. This study uses the ROC curve to formulate the MCID value of the Quality of Life Instruments for Chronic Diseases of Systemic lupus erythematosus (QLICD-SLE V2.0) scale. Using the representative item “In general, would you say your health is” of the MOS item short form health survey(SF-36) as an anchor, the questionnaire of QLICD-SLE V2.0 and the anchor item were used to investigate the patients on the first day of hospitalization, and the day before the patient was discharged. 279 patients with lupus erythematosus were participated in this longitudinal follow-up study. The ROC curve was constructed by using the classification based on the anchor item as the gold standard and the difference score of the scale as the test variable. The cut-off point corresponding to the maximum value of the Youden index in the ROC curve is taken as the minimum clinical importance difference (MCID) value of the QLICD-SLE (V2.0) scale. The Results showed that the MCID of physical domain, psychological domain, social domain, general module, specific module and QLICD-SLE (V2.0) total scale are 8.3, 2.3, 2.5, 2.7, 9.2 and 3.2, respectively. Area under the ROC curve of QLICD-SLE (V2.0) is 0.898, P (Area = 0.5) < 0.001, the sensitivity is 100%, the specificity is 66.9%. It concluded that if the total scores after treatments changes at least 3.2 points positively, the treatment intervention can be considered as clinically significant. It is more convincing to use the corresponding cut-off point as the MCID for ROC curve method can visualize the sensitivity and specificity.

In vitro evaluation of some mechanical properties and fluoride release of glass-ionomer cement modified with seashell nanoparticles.

This research assessed the compressive strength and microhardness of glass-ionomer cement (GIC) after incorporating seashell nanoparticles and evaluated the inert fluoride-releasing ability. Seashell nanoparticles were synthesized by a mechanical grinding protocol. These particles were characterized by transmission electron microscopy and energy dispersive x-ray and added to the glass-ionomer powder in a weight-to-weight ratio. Seventy-five study samples were distributed into eight samples for each study group (control, 5%, and 10% seashell) to have 24 samples for each test of the study (compressive strength, microhardness, and fluoride release). One sample per group was prepared for the Fourier transform infrared spectroscopy (FTIR) test. The fluoride ion release was measured after one and four weeks of incubation period at 37 ºC, while other tests were conducted after 24 hours of incubation. In all the test variables, the 10% seashell group showed the highest significant mean, followed by the 5% seashell and the control group. However, there was no significant difference between the 5% and 10% seashell groups in the first week of fluoride release. According to the results, 10% seashell nanoparticles were the best to improve the mechanical properties of GIC and boost the fluoride-releasing potential.

Shear Behavior of High-Strength and Lightweight Cementitious Composites Containing Hollow Glass Microspheres and Carbon Nanotubes

In this study, an experimental program was conducted to investigate the shear behavior of beams made of high-strength and lightweight cementitious composites (HS-LWCCs) containing hollow glass microspheres and carbon nanotubes. The compressive strength and dry density of the HS-LWCCs were 87.8 MPa and1.52 t/m3, respectively. To investigate their shear behavior, HS-LWCC beams with longitudinal rebars were fabricated. In this test program, the longitudinal and shear reinforcement ratios were considered as the test variables. The HS-LWCC beams were compared with ordinary high-strength concrete (HSC) beams with a compressive strength of 89.3 MPa to determine their differences; the beams had the same reinforcement configuration. The test results indicated that the initial stiffness and shear capacity of the HS-LWCC beams were lower than those of the HSC beams. These results suggested that the low shear resistance of the HS-LWCC beams led to brittle failure. This was attributed to the beams’ low elastic modulus under compression and the absence of a coarse aggregate. Furthermore, the difference in the shear capacity of the HSC and HS-LWCC beams slightly decreased as the shear reinforcement ratio increased. The diagonal compression strut angle and diagonal crack angle of the HS-LWCC beams with shear reinforcement were more inclined than those of the HSC beams. This indicated that the lower shear resistance of the HS-LWCCs could be more effectively compensated for when shear reinforcement is provided and the diagonal crack angle is more inclined. The ultimate shear capacities measured in the tests were compared with various shear design provisions, including those of ACI-318, EC2, and CSA A23.3. This comparison showed that the current shear design provisions considerably overestimate the contribution of concrete to the shear capacity of HS-LWCC beams.

Cervical Sensorimotor Function Tests Using a VR Headset-An Evaluation of Concurrent Validity.

Sensorimotor disturbances such as disturbed cervical joint position sense (JPS) and reduced reaction time and velocity in fast cervical movements have been demonstrated in people with neck pain. While these sensorimotor functions have been assessed mainly in movement science laboratories, new sensor technology enables objective assessments in the clinic. The aim was to investigate concurrent validity of a VR-based JPS test and a new cervical reaction acuity (CRA) test. Twenty participants, thirteen asymptomatic and seven with neck pain, participated in this cross-sectional study. The JPS test, including outcome measures of absolute error (AE), constant error (CE), and variable error (VE), and the CRA test, including outcome measures of reaction time and maximum velocity, were performed using a VR headset and compared to a gold standard optical motion capture system. The mean bias (assessed with the Bland-Altman method) between VR and the gold standard system ranged from 0.0° to 2.4° for the JPS test variables. For the CRA test, reaction times demonstrated a mean bias of -19.9 milliseconds (ms), and maximum velocity a mean bias of -6.5 degrees per seconds (°/s). The intraclass correlation coefficients (ICCs) between VR and gold standard were good to excellent (ICC 0.835-0.998) for the JPS test, and excellent (ICC 0.931-0.954) for reaction time and maximum velocity for the CRA test. The results show acceptable concurrent validity for the VR technology for assessment of JPS and CRA. A slightly larger bias was observed in JPS left rotation which should be considered in future research.