Reverse Test Research Articles

Ninety-day toxicity and genotoxic effects of synthetically derived fully saturated forms of anacardic acid in mice

Organically synthesized fully saturated form of Anacardic acid (AA) has previously shown to be effective in the treatment of inflammatory autoimmune disease. In this study, organically synthesized fully saturated form of AA was orally administered to male and female Swiss albino mice for 90 consecutive days at doses of 25, 50 and 100 mg/kg BW (n = 20 per sex/group). Administration of AA was well tolerated at all dose levels. The treated animals did not show a dose-response toxicity in their hematology, liver, or metabolic profile. Minimally significant changes in serum biochemistry and hematology parameters were noted, but these were not considered to be of biological or toxicological importance and were not outside the known accepted ranges. Sporadic differences in organ weights were observed between groups, but all were minimal (<10%) and unlikely to indicate toxicity. The incidence of histopathological lesions was comparable between treated and control groups across all tested organs. Based upon these findings, the no-observed-adverse-effect level was determined to be ≥ 100 mg/kg BW, which was the highest dose tested. There were no genotoxic (mutagenic and clastogenic) effects seen in In-vivo micronucleus test, In-vitro chromosomal aberration test and Bacterial reverse mutation test. These results support, no genotoxicity and no toxicity associated with oral consumption of AA in mice as a dietary supplement for beverages and food.

Predicting COVID-19 Outcomes: Machine Learning Predictions Across Diverse Datasets.

Background The COVID-19 infection has spread rapidly since its emergence and has affected a large part of the global population. With the increasing number of cases, researchers are trying to predict the prognosis of patients by using different data with artificial intelligence methods such as machine learning (ML). In this study, we aimed to predict mortality risk in COVID-19 patients using ML algorithms with different datasets. Methodology In this retrospective study, we evaluated the fever, oxygen saturation, laboratory results, thorax computed tomography (CT) findings, and comorbid diseases at admission to the hospital of 404 patients whose diagnosis was confirmed by the reverse transcription polymerase chain reaction test. Different datasets were created by combining the data. The Synthetic Minority Oversampling Technique was used to reduce the imbalance in the dataset. K-nearest neighbors, support vector machine, stochastic gradient descent, random forest, neural network, naive Bayes, logistic regression, gradient boosting, XGBoost, and AdaBoost models were used to create the ML algorithm, and the accuracy rates of mortality prediction were compared. Results When the dataset was created with CT parenchyma score, pulmonary artery and inferior vena cava diameters, and laboratory results, mortality was predicted with an accuracy of 98.4% with the gradient boosting model. Conclusions The study demonstrates that patient prognosis can be accurately predicted using simple measurements from thorax CT scans and laboratory findings.

A novel “AIE+ESIPT” mechanism-based fluorescent probe for visual alternating recognition of HSO3−/H2O2 and its HSO3− detection in food samples

Maintaining redox homeostasis in organisms plays a crucial role in human life and health, and changes in the levels of SO2 and H2O2, as typical representative substances of reductants and oxidants, directly affects intracellular redox homeostasis. Hence, it is necessary to manufacture fluorescent probes that can detect HSO3− and H2O2. In this work, a benzopyrylium salt containing benzothiazole derived fluorescent probe HBTO-H with dual properties of aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) has been developed. The probe displays rapid and reversible test of HSO3− and H2O2 in DMF/Tris (v:v = 2:8, pH = 7.3, Tris 10 mM) mixed solvent with high selectivity, good anti-interference ability and a wide applicable pH range (6–11). The detection limits of HBTO-H for HSO3− and H2O2 are 0.187 μM and 0.152 μM, respectively. The response mechanisms of HBTO-H toward HSO3− and H2O2 have been demonstrated to be Michael addition reaction and its retro-reaction based on 1H NMR and HRMS analyses. In addition, HBTO-H has been successfully applied to check HSO3− in sugar and wine specimens. Moreover, HBTO-H was proved to be mitochondria-targetable and can alternately detect exogenous HSO3− and H2O2 in MCF-7 cells, which is desired to be applied to trace HSO3− in organisms in the future.

Mutagenicity and safety evaluation of Ashwagandha (Withania somnifera) root aqueous extract in different models

Withania somnifera (Ashwagandha) also called as Indian ginseng, a revered herb from Indian traditional system of medicine is a rejuvenator and tonic (Rasayana) used for its varied benefits. The roots of ashwagandha exhibit properties like anti-inflammatory, aphrodisiac, anthelmintic, astringent, diuretic, stimulant and thermogenic. However, data of ashwagandha on its mutagenic effects are lacking. In the present study, in-vitro genotoxicity tests were used to evaluate the mutagenic potential of Ashwagandha Root Extract (ARE). Concentrations of 0.156 to 5.00 mg/plate ARE were used for conducting Bacterial reverse mutation test (BRMT). For chromosome aberration (CA) test ARE was used in concentrations of 0.25 to 2.00 mg/ml, and for micronucleus (MN) tests ARE concentrations of 500/1000/2000 mg/kg were used. Acute oral toxicity was conducted in Wistar rats (n = 25) as per the OECD guideline (#423) with doses of 500/1000/2000 mg/kg body weight in male Swiss albino mice for morbidity and mortality for 3 days. The BRMT and CA tests were conducted with and without metabolic activation (S9). The study was approved by the institutional ethics committee (IEC) and institutional animal ethics committee (IAEC). ARE failed to show any mutagenic effects up to a dose of 5 mg/plate in BRMT. Also, ARE did not show any clastogenic activity in doses up to 2 mg/ml in CA test and in micronucleus test up to 2000 mg/kg body weight. These results were observed with and without metabolic activation (S9) under the stated experimental conditions. No mortality, morbidity, or any clinical signs were observed up to 3 days following ARE administration. Ashwagandha root extract failed to show any mortality in doses up to 2000 mg/kg oral dosage and did not show any mutagenic (genotoxic) effects in high concentrations.

Direct Impact of the Air on Mutant Cells for Mutagenicity Assessments in Urban Environments.

Urban air pollution is recognized as a critical problem for public health and is classified as a carcinogen for humans. A great number of studies have focused on the monitoring of urban air mutagenicity. One of the best-known and applied methods for assessing mutagenicity is the Ames test, a bacterial reverse mutation test. The classic protocol for assessing air mutagenicity involves the concentration of particulate matter (PM) on filters and subsequent extraction using organic solvents. This work aimed to develop a method for the evaluation of air mutagenicity directly impacted by air on microbial plates already containing an Ames' microbial sensor. A specific six-month sampling campaign was carried out in Turin in a period with high air pollution. Samples were tested for mutagenicity on Salmonella typhimurium strains TA98, TA100, and YG1024 with the traditional method and with the new direct method. The new protocol is able to evaluate the mutagenicity of the sampled air and obtain repeatable results. The final sensitivity is similar to the traditional method (≈10 net revertants/m3); however, the mutagenic response is due to the complete air pollution mixture, including volatile and semivolatile pollutants avoiding the concentration of filters and the following laborious extraction procedures. Despite some critical issues in contamination control, the method is easier, faster, and less expensive than traditional methods.

Assessment of the genotoxic and mutagenic effects induced by T-2 mycotoxin in HepG2 cells

The T-2 toxin is a mycotoxin produced by molds belonging to Fusarium. Among the Fusarium mycotoxins, trichothecenes are frequently reported in food and feed, being the T-2 toxin (T-2) the mycotoxin which possesses the highest toxicity. According to EFSA, T-2 is found in various cereal grains used in food and feed products, mainly in oats, and it has a high environmental impact due to its mechanisms of toxicity. However, recent information on its genotoxic and mutagenic effects is lacking. This work aimed to evaluate the genotoxic and mutagenic potential of T-2 in vitro. For this purpose, HepG2 cells were exposed to 15, 30, and 60 nM T-2 for 24 h, then the DNA damage was evaluated by the micronucleus and the comet assays. In addition, point mutation analysis was performed by the bacterial reverse mutation test using 0.15–60 nM of T-2 concentrations. The results showed chromosomal damage at 60 nM T-2 since significantly more MN appeared at this concentration than in the control samples. Regarding the comet assay, DNA double helix breaks appeared at all concentrations tested and, in a concentration-dependent manner. However, no mutagenic effects were observed at any of the concentrations tested for the Salmonella typhimurium (S. Typhimurium) strains TA98, TA100, TA1535, TA1537, or the Escherichia coli (E. Coli) WP2 strain in the absence or presence of a metabolic activation system. Therefore, these results showed that T-2 mycotoxin produced genotoxic effects by MN and comet assay, while no mutagenicity was observed. However, further research simulating different metabolic activation pathways and the combined exposure of this mycotoxin with other mutagenic chemicals that could be present in the diet is necessary to discard the mutagenic potential of T-2 fully. These results highlight the carcinogenic potential and danger associated with T-2 exposure and should be considered to prevent associated food risks for the human population.

Seismic behavior and restoring force model of precast beam-column connections with locally reactive powder concrete

In this study, an innovative approach to enhance the seismic performance of prefabricated concrete frame beam-column joints, incorporating high-strength steel bars and reactive powder concrete (RPC), was developed. The research involved the construction of four prefabricated joints and one cast-in-place node, subjecting them to low-cycle reverse load tests. The findings indicate that the inclusion of high-strength steel bars in the node core area led to a notable increase in load-bearing capacity, ranging from 9.5 % to 9.7 %. Moreover, when RPC and high-strength steel bars were simultaneously used in the node core area, the load-bearing capacity improved even further, with an increase of 19.1 %–20.8 %. Additionally, RPC was found to enhance crack resistance in columns and beams, reducing the severity of node failures. Comparing specimens with different spacing of hoops in the core area, it was observed that RPC not only ensured the seismic performance of the nodes but also addressed the issue of excessive hoop density in the core area. Through experimental data, a restoring force model for prefabricated RPC/RC composite frame beam-column joints was established using theoretical analysis. This model exhibited strong agreement with experimental results and effectively depicted the stress distribution within the proposed joints at various stages.

Frequency adaptive conductivity measurement based on reverse approximation

Accurately measuring the solution conductivity is important both for environmental assessment and process monitoring. A reverse approximation frequency adaptive conductivity test method is proposed in this paper. This method avoids the complex calculation of the time constant τ of the first-order resistance-capacitance network and eliminates the influence of the accessory capacitance on the measurement results to the greatest extent. Through 9 groups of optimal frequency selection experiments, the optimal measurement frequency of R1 and Rx fixed ratio in a certain range is obtained. The optimal measurement frequency and dimensionless relationship model constitute a complete frequency adaptive solution conductivity measurement method.Through comparative analysis, the mean absolute percentage error of the measurement results is 2.65%, which not only improves the measurement accuracy of the existing self-developed equipment but also provides a new solution to solve the influence of additional capacitance in the conductivity measurement process.

Pseudo-chilblain lesions in children during the COVID-19 pandemic

Introduction and objective: During the COVID-19 pandemic, a range of uncommon cutaneous symptoms were observed, which were linked to the SARS-CoV-2 infection. These dermatological symptoms in the form of reddish or purple-coloured lesions on the fingers and toes, accompanied by blisters and ulcerations, were termed as “COVID fingers/toes” – a pseudo-chilblain cutaneous manifestation of COVID-19. The aetiopathogenesis of pseudo-chilblain lesions has not been conclusively determined. At first, SARS-CoV-2 infection was regarded as an evident cause of chilblains. Various studies conducted over a two-year period have not managed to plausibly confirm its direct implications. Materials and methods: The study was of a retrospective nature. The analysis involved clinical symptoms, results of selected laboratory tests, as well as capillaroscopy of the microcirculation in 15 children diagnosed with skin lesions of chilblain-like morphology. Results: All patients from the study population presented with lesions in distal body parts which were of erythematous or oedematous morphology, and resembled chilblains. None of the hospitalised patients suffered from fever or presented with other systemic symptoms. The reverse transcription polymerase chain reaction test for SARS-CoV-2 was negative in all the patients. SARS-CoV-2 antibodies were found in 5 out of 9 patients tested for their presence. Microcirculation abnormalities were diagnosed in 80% of the patients. In none of the children did capillaroscopy image correspond with microangiopathy characteristic of inflammatory connective tissue diseases. Frequent abnormalities found in more than two fingers/toes were: pericapillary oedema (57%), dilated capillaries (42.8%), venous stasis (35.7%), presence of branched and tortuous capillaries (28.5%). Conclusions: Pseudo-chilblain lesions observed during the SARS-CoV-2 pandemic are probably secondary to multifactorial epiphenomenon.

Research on the bi-directional bending performance of plug-pin scaffold joints in low-temperature

In this paper, a pinned scaffolding node is proposed and studied with Q355 steel and sorbite stainless steel. Twelve sets of forward and reverse bending tests were designed to study the bi-directional bending performance at temperatures of +20 °C, −20 °C, and − 40 °C. The test results show that as the temperature decreases, the initial rotational stiffness and bearing capacity of the QSJ and the SSSJ both increase. Under the same temperature conditions, the yield bearing capacity and maximum bearing capacity of the SSSJ are greater than those of the QSJ. However, the SSSJ is susceptible to cracking in the weak zone of the C-shaped member subjected to forward bending moments in low-temperature environments, which requires attention in design and use. A finite element model can accurately simulate the bi-directional bending performance of the joint. The results show that increasing the thickness of the U-shaped members by 1–1.5 mm significantly increases the maximum load capacity of the joint. The wall thickness of the pipe has no influence on the bending properties of the joint, but the initial stiffness of the joint can be increased by the depth of wedging, a wall thickness of 6 mm is recommended for C-members. The form of damage to the SSSJ can be improved by increasing the curvature of the upper edge of the C-member at the wedge. The results of this paper can provide methods and references for the engineering design of scaffolding as well as for testing in low-temperature environments.

Radiographic patterns and severity scoring of COVID-19 pneumonia in children: a retrospective study

BackgroundChest radiography (CXR) is an adjunct tool in treatment planning and monitoring of the disease course of COVID-19 pneumonia. The purpose of the study was to describe the radiographic patterns and severity scores of abnormal CXR findings in children diagnosed with COVID-19 pneumonia.MethodsThis retrospective study included children with confirmed COVID-19 by reverse transcriptase-polymerase chain reaction test who underwent CXR at the arrival. The CXR findings were reviewed, and modified radiographic scoring was assessed.ResultsThe number of abnormal CXR findings was 106 of 976 (10.9%). Ground-glass opacity (GGO) was commonly found in children aged > 9 years (19/26, 73.1%), whereas peribronchial thickening was predominantly found in children aged < 5 years (25/54, 46.3%). Overall, the most common radiographic finding was peribronchial thickening (54/106, 51%). The lower lung zone (56/106, 52.8%) was the most common affected area, and there was neither peripheral nor perihilar predominance (84/106, 79.2%). Regarding the severity of COVID-19 pneumonia based on abnormal CXR findings, 81 of 106 cases (76.4%) had mild lung abnormalities. Moderate and severe lung abnormalities were found in 21 (19.8%) and 4 (3.8%) cases, respectively. While there were no significant differences in the radiographic severity scores among the various pediatric age groups, there were significant disparities in severity scores in the initial CXR and medical treatments.ConclusionsThis study clarified the age distribution of radiographic features across the pediatric population. GGO was commonly found in children aged > 9 years, whereas peribronchial thickening was predominant in children aged < 5 years. The lower lung zone was the most common affected area, and the high severity lung scores required more medical treatments and oxygen support.

Stressing dynamic loss models

Stress testing, and in particular, reverse stress testing, is a prominent exercise in risk management practice. Reverse stress testing, in contrast to (forward) stress testing, aims to find an alternative but plausible model such that under that alternative model, specific adverse stresses (i.e. constraints) are satisfied. Here, we propose a reverse stress testing framework for dynamic models. Specifically, we consider a compound Poisson process over a finite time horizon and stresses composed of expected values of functions applied to the process at the terminal time. We then define the stressed model as the probability measure under which the process satisfies the constraints and which minimizes the Kullback-Leibler divergence to the reference compound Poisson model.We solve this optimization problem, prove existence and uniqueness of the stressed probability measure, and provide a characterization of the Radon-Nikodym derivative from the reference model to the stressed model. We find that under the stressed measure, the intensity and the severity distribution of the process depend on time and state, and hence the stressed model is not a compound Poisson process. We illustrate the dynamic stress testing by considering stresses on VaR and both VaR and CVaR jointly and provide illustrations of how the stochastic process is altered under these stresses. We generalize the framework to multivariate compound Poisson processes and stresses at times other than the terminal time. We illustrate the applicability of our framework by considering “what if” scenarios, where we answer the question: What is the severity of a stress on a portfolio component at an earlier time such that the aggregate portfolio exceeds a risk threshold at the terminal time? Furthermore, for general constraints, we propose an algorithm to simulate sample paths under the stressed measure, thus allowing to compare the effects of stresses on the dynamics of the process.

Revisiting Pulmonary Hypertension in the Era of Temporary Mechanical Circulatory Support – Literature Review and Case-Based Discussion

Pulmonary arterial hypertension (PAH) is characterized by persistently increased pressure in the pulmonary arteries. New defining criteria for the different hemodynamic types of pulmonary hypertension (PH) that occur with left heart disease have been proposed by the task force on PH. After consideration of the changes in the general definition of PH in left heart disease, the proposed hemodynamic definition was: (1) isolated postcapillary PH: pulmonary artery wedge pressure >15 mm Hg and mean pulmonary arterial pressure (mPAP) >20 mm Hg and pulmonary vascular resistance (PVR) <3 Woods units (WU); and (2) combined post- and precapillary PH: pulmonary artery wedge pressure >15 mm Hg, mPAP >20 mm Hg, and PVR ≥3 WU. Secondary PH is initially reversible, but eventually, it can become fixed because of the remodeling process of the pulmonary vascular system. Limitations in defining both the time for and amount of reversibility lack clarity. We discuss a case of PH as a framework to better understand these key principles in addressing patients' candidacy for heart or heart-lung transplantation. We performed a literature search for all available contemporary data with the following terms: "pulmonary hypertension," "reversal," "Impella 5.5," "temporary mechanical support," and "LVAD" using the National Library of Medicine - PubMed and PubMed Central between 2019 and 2023. A total of 14 published papers were found with these search. From these, 3 addressed the issue of PH and reversibility in the setting of LHD after durable LVAD placement. No papers were found using Impella 5.5 and PH during this timeframe. Given the paucity of data in the field regarding temporary mechanical circulatory support and pulmonary hypertension, we present a case-based discussion to guide the reader in understanding the potential impact of this method in patients with WHO Class 2 Pulmonary hypertension. A 49-year-old woman with a medical history of acute on chronic biventricular systolic and diastolic heart failure, American College of Cardiology stage D, Stevenson profile C, New York Heart Association class IV (ejection fraction 18%) secondary to nonischemic cardiomyopathy after cardiac resynchronization therapy, pulmonary hypertension, bilateral deep vein thrombosis, and segmental pulmonary embolism presented for heart transplant evaluation. Her cardiac output and central hemodynamics were measured, and she was found to have a pulmonary artery (PA) pressure of 78/38 with a mean PA pressure of 51, pulmonary capillary wedge pressure (PCWP) 30, transpulmonary pressure gradient (TPG) 21, thermodilution cardiac output (CO) 3.35 L/min, and cardiac input (CI) 1.75 L/min/m2. Her PVR was 6.2 WU. Provocative pharmacologic testing for reversibility of PH was performed using sodium nitroprusside, which resulted in a blood pressure of 83/57 (92), heart rate 92/min, and PA pressure of 71/31, with a mean PA pressure of 44 PCWP 22, TPG 22, CO 4.8 L/min, and CI of 2.48 L/min/m2 with a PVR of 4.5 WU. Following this, the patient underwent Impella 5.5 placement through the right axillary artery to optimize afterload reduction and improve end-organ perfusion. Post-Impella hemodynamics on milrinone 0.5 mcg/kg/min demonstrated the following: blood pressure 90/66 (74), heart rate 53/min, and PA pressure of 56/29, with a mean PA pressure of 38, PCWP 24, TPG 14, CO 6 L/min, and CI of 2.9 L/min/m2 with a PVR of 2.3 WU. Left ventricular assist device support with Impella 5.5 is associated with a reduction in mPAP and PVR over weeks to months and thus plays a crucial role as a bridge to transplant. Our case and this review highlights the characteristics of PH resulting from heart failure with reduced ejection fraction and discusses the important clinical issues related to the treatment of these patients. We have shown that left ventricular assist device therapy with Impella 5.5 can effectively reduce left-sided filling pressures and lead to PH improvement. We demonstrate the potential benefits of Impella 5.5 in the management of patients with WHO 2 PH and cardiogenic shock with impaired hemodynamics.

Improved Durability of Ti3C2Tz at Potentials above the Reversible Hydrogen Electrode by Tantalum Substitution

AbstractMXenes have gained significant attention, particularly Ti3C2Tz, as materials with favorable properties for energy storage and conversion applications. The overwhelming majority of electrochemical durability studies are based on durability in the hydrogen evolution window, well below the reversible hydrogen electrode where degradation via electrochemical oxidation is less relevant. Consequently, few strategies have been put forward to protect Ti3C2Tz at higher potentials and widen their applicability to electrochemical systems. Here, the electrochemical degradation of pristine Ti3C2Tz and tantalum (Ta)‐substituted (Ti0.95Ta0.05)3C2Tz is reported. X‐ray photoelectron spectroscopy and electron microscopy revealed that pristine and Ta‐doped MXene went through entirely different degradation mechanisms, and that these mechanisms are driven by electrochemical, rather than chemical effects. Density functional theory is used to explain the role of Ta doping with respect to the binding of oxygen and the formation of metal oxide phases. The influence of the degradation mechanism is observed by accelerated stress tests and anode reversal tests on a polymer electrolyte membrane fuel cell. Therefore, the substitution of titanium (Ti) with other oxyphilic metals in Ti3C2Tz may be an effective route to improve the durability of the otherwise fragile MXene phase.

The effect of induced precipitations and pre-twins on the bending neutral layer migration behaviors of AZ80 Mg alloy sheet

To explore the effect of the precipitated phase particles and twins on the microstructure evolution and neutral layer evolution during bending, {10–12} tensile twins were introduced along the transverse direction (TD) on AZ80 Mg alloy sheets at room temperature. Then pre-compressed samples were aged to induce more precipitations. The reverse tensile tests were carried out at room temperature, and the three-point bending deformation was carried out at 100 °C. After aging treatment, precipitations increased. The results showed that twin crystals can promote precipitation formation. And the YS (yield strength) values of the pre-twinned aged samples were significantly larger than that before aging. During the bending process on the pre-compressed samples, the outside of the sample was dominated by the detwinning behaviors, while the inside region was dominated mainly by twinning. For pre-compressed bending samples, the k values were smaller than the initial bending sample. The tension and compression asymmetry in its inner and outer regions was weaker than that of the original bending sample. The existence of precipitations hindered the detwinning behaviors in outside the pre-twinning aged bending samples, and the twinning in inner region was restrained as well so that the inner and outer tension asymmetry decreased. The k values were smaller than that of the unaged samples, which was beneficial to weaken the bending springback of Mg alloy sheets.

Fretting Wear of Metal–Metalopolymer Friction Couples

Test results on fretting wear of metalopolymer materials in a friction couple with structural materials—cast iron 20 and stainless steel 12Kh18N10T—performed over the direct and reverse test schemes are presented. As the metalopolymer material, we took the BELZONA 1111 two-component paste-like material based on a mixture of a metal–ceramic alloy with high-molecular polymers and oligomers.

The Impact of Emotions on Habitual Inhibition.

Emotional information prioritizes human behavior. How much emotions influence ongoing behavior critically depends on the extent of executive control functions in a given context. One form of executive control is based on stimulus-stop associations (i.e., habitual inhibition) that rapidly and effortlessly elicits control over the interruption of ongoing behavior. So far, no behavioral accounts have explored the emotional impact on habitual inhibition. We aimed to examine the emotional modulation on habitual inhibition and associated psycho-physiological changes. A go/no-go association task asked participants to learn stimulus-stop and stimulus-response associations during 10-day training to form habitual inhibition (without emotional interference). Probabilistic feedback guided learning with varying probabilities of congruent feedback, generating stronger versus weaker pairings. A reversal test measured habitual inhibition strength counteracted by emotional cues (high-arousal positive and negative stimuli compared with neutral ones). Our training protocol induced stable behavioral and psycho-physiological responses compatible with habitual behavior. At reversal, habitual inhibition was evident as marked by significant speed costs of reversed no-go trials for strongly associated stimuli. Positive and negative emotional cues produced larger impact on habitual inhibition. We report first evidence on a cognitive control mechanism that is vulnerable to emotional stimuli and suggest alternative explanations on how emotions may boost or counteract certain behavioral abnormalities mediated by habitual inhibition.

Timing the Hegenshan Suture in the Central Asian Orogenic Belt: New Paleomagnetic and Geochronological Constraints From Southeastern Mongolia

AbstractThe timing of formation of the Hegenshan suture is crucial to understanding the evolution of the Central Asian Orogenic Belt (CAOB). Here we present a well‐dated paleomagnetic pole (103 samples from 15 sites, 36.7°N/29.2°E, A95 = 3.3°) that passed a positive fold test, a reversal test, and a conglomerate test from the ∼250 Ma upper Gunbayn Formation andesites in the southeastern Mongolia Block (MOB). The high‐quality paleomagnetic database may demonstrate that the MOB drifted rapidly southward and collided with the Xilinhot–Songliao Block between 256 and 250 Ma, resulting in the closure of the Hegenshan Ocean at ∼250 Ma. The Hegenshan suture and the Solonker suture were formed almost simultaneously and marked the final closure of the Paleo‐Asian Ocean.

Insight into the synergistic behaviors of a hydroxyethyl cellulose-based graft copolymer in the mitigation of silica scaling: Combined static and reverse osmosis tests

Silica scaling has become a common problem in membrane systems due to the ubiquity of silica in the natural environment. In this work, a series of N-[3-(dimethylamino)propyl]methacrylamide-grafted hydroxyethyl cellulose (DHEC) with different grafting ratios was designed and used as a silica scaling inhibitor. The performances and mechanisms of DHEC in the inhibition of silica scaling were evaluated in detail by static and reverse osmosis (RO) tests. The maximum inhibition efficiency of DHEC with the grafting ratio of 97% reached as high as 77.20% ± 0.26% in the static test. The permeate flux in the presence of this DHEC gradually decreased and was eventually maintained at 89.12% after 10 h of RO operation. The efficient mitigation of silica scaling was ascribed to the synergistic effect of the grafted copolymer, specifically, the hydrophilic cellulose backbone of DHEC exerted a dispersion effect and the cationic grafted chains acted as aggregators to inhibit silica scaling in the solution and at the membrane surface. This synergistic effect cannot delay the induction time of silica polymerization but can change the dominant mode of polymerization in the solution from the first-order to the second-order reaction as confirmed by the kinetic study. Thus, DHEC is an efficient and environmentally friendly inhibitor with high application potential for membrane fouling control in RO operations.

Investigating Ecological Momentary Assessed Physical Activity and Core Executive Functions in 18- to 24-Year-Old Undergraduate Students.

Although evidence for young children (<10) and older adults (>64) highlights an association between physical activity (PA) and executive functions (EFs), there is a paucity of research on adolescents aged 18-24 years. Thus, this study examined the associations between PA and EF and the difference in EF between individuals who achieve the moderate-to-vigorous (MVPA) guidelines and those who do not. Forty-seven participants engaged in a Stroop task, a reverse Corsi-block test, and a task-switching test, to measure inhibition, working memory, and cognitive flexibility, respectively. An ecological momentary assessment (EMA) was used to determine the participant's MVPA and step count, through the "Pathverse" app. Multiple regressions were run to predict the task-switch cost, the Stroop effect, and the backward Corsi span from time spent in MVPA. A two-way ANCOVA examined the effects of achieving the MVPA guidelines on EF. MVPA and step count did not significantly predict EF. There were no significant differences in EF between participants achieving the MVPA guidelines and those that did not. Time spent in MVPA and step count were not significantly associated with working memory, cognitive flexibility, or inhibition in adolescents. Further research is warranted to understand other factors that may significantly affect EF, within and outside an individual's control.