Initial Rapid Decline Research Articles

Colloidal Synthesis and Analysis of CNT-Cu2S for Stability and Capacity Increase Alleviation in Sodium-Ion Storage.

With the growing interest in energy storage, significant research has focused on finding suitable anode materials for sodium-ion batteries (SIBs). While developing high-capacity nanosized metal sulfides, issues like low stability and rapid initial capacity decline are common. Instead of maintaining steady capacity, they also tend to exhibit an increase in discharge capacity as cycling continues. We introduce CNT-Cu2S, featuring Cu2S nanoplates integrated onto the surface of MWCNTs, and assess its electrochemical properties for SIBs. Cu2S initially exhibited a rapid decrease in capacity and then showed increased capacity. In contrast, CNT-Cu2S demonstrated a stable capacity of 344.8 mAh g-1 at 2.0 A g-1 over 800 cycles, close to the theoretical capacity with capacitive behavior. This paper carried out analysis using data from in situ EIS and overpotential data from GITT to explain the different outcomes between the Cu2S and CNT-Cu2S experiments. These results show that CNT-Cu2S is a suitable anode material for SIBs.

The Curious Case of Aistija: Sidelights on Latvian–Lithuanian Rapprochement During the 20th Century

The nascent Aistijan movement centred around the idea of establishing a Latvian–Lithuanian state following the Second World War. This article surveys the background of the idea, with particular attention to the public diplomacy of Lithuanian American émigrés, demonstrating its prevalence during the First World War. The activities of interwar Latvian and Lithuanian rapprochement societies are outlined, noting the prominence of the Aestii – the earliest recorded inhabitants of the eastern littoral of the Baltic Sea – in both academic and popular history, in addition to the emergence of the Aistijan movement following the Second World War. Examining the initial successes and rapid decline of the movement, the article also charts developments and material circumstances of language learning practices in connection with the idea of a Latvian–Lithuanian state.

Consequences of a 2-Deoxyglucose Exposure on the ATP Content and the Cytosolic Glucose Metabolism of Cultured Primary Rat Astrocytes

The glucose analogue 2-deoxyglucose (2DG) has frequently been used as a tool to study cellular glucose uptake and to inhibit glycolysis. Exposure of primary cultured astrocytes to 2DG caused a time- and concentration-dependent cellular accumulation of 2-deoxyglucose-6-phosphate (2DG6P) that was accompanied by a rapid initial decline in cellular ATP content. Inhibitors of mitochondrial respiration as well as inhibitors of mitochondrial uptake of pyruvate and activated fatty acids accelerated the ATP loss, demonstrating that mitochondrial ATP regeneration contributes to the partial maintenance of the ATP content in 2DG-treated astrocytes. After a 30 min exposure to 10 mM 2DG the specific content of cellular 2DG6P had accumulated to around 150 nmol/mg, while cellular ATP was lowered by 50% to around 16 nmol/mg. Following such a 2DG6P-loading of astrocytes, glycolytic lactate production from applied glucose was severely impaired during the initial 60 min of incubation, but was reestablished during longer incubation concomitant with a loss in cellular 2DG6P content. In contrast to glycolysis, the glucose-dependent NADPH regeneration via the pentose phosphate pathway (PPP) was only weakly affected in 2DG6P-loaded astrocytes and in cells that were coincubated with glucose in the presence of an excess of 2DG. Additionally, in the presence of 2DG PPP-dependent WST1 reduction was found to have doubled compared to hexose-free control incubations, indicating that cellular 2DG6P can serve as substrate for NADPH regeneration by the astrocytic PPP. The data presented provide new insights on the metabolic consequences of a 2DG exposure on the energy and glucose metabolism of astrocytes and demonstrate the reversibility of the inhibitory potential of a 2DG-treatment on the glucose metabolism of cultured astrocytes.

Injection of luteinizing hormone or human chorionic gonadotropin increases calcium excretion and serum PTH in males

Animal and human studies have suggested that sex steroids have calciotropic actions, and it has been proposed that follicle-stimulating hormone (FSH) may exert direct effects on bone. Here, we demonstrate the expression of the receptor for Luteinizing hormone (LH) and human choriogonadotropin (hCG), LHCGR, in human kidney tissue, suggesting a potential influence on calcium homeostasis. To investigate the role of LHCGR agonist on calcium homeostasis in vivo, we conducted studies in male mice and human subjects. Male mice were treated with luteinizing hormone (LH), and human extrapolation was achieved by injecting 5000 IU hCG once to healthy men or men with hypergonadotropic or hypogonadotropic hypogonadism. In mice, LH treatment significantly increased urinary calcium excretion and induced a secondary increase in serum parathyroid hormone (PTH). Similarly, hCG treatment in healthy men led to a significant increase in urinary calcium excretion, serum PTH levels, and 1,25 (OH)2D3, while calcitonin, and albumin levels were reduced, possibly to avoid development of persistent hypocalcemia. Still, the rapid initial decline in ionized calcium coincided with a significant prolongation of the cardiac QTc-interval that normalized over time. The observed effects may be attributed to LH/hCG-receptor (LHCGR) activation, considering the presence of LHCGR expression in human kidney tissue, and the increase in sex steroids occurred several hours after the changes in calcium homeostasis. Our translational study shed light on the intricate relationship between gonadotropins, sex hormones and calcium, suggesting that LHCGR may be influencing calcium homeostasis directly or indirectly.

Atherosclerotic cardiovascular disease landscape in Singapore.

Cardiovascular disease (CVD) is the leading cause of death worldwide, accounting for over one-third of all deaths in Singapore. An analysis of age-standardized mortality rates (ASMR) for CVD in Singapore revealed a deceleration in the initial rapid decline in ASMR. A decrease in smoking prevalence may have contributed to the initial rapid decline in ASMR. Furthermore, other major risk factors, such as diabetes mellitus, hypertension, elevated low-density lipoprotein levels, and obesity, are steadily rising. Singapore's CVD economic burden is estimated to be 8.1 billion USD (11.5 billion SGD). The burden of CVD can only be reduced using individual and population-based approaches. Prevention programs must also be developed based on an understanding of risk trends. Therefore, this article attempts to capture the burden of CVD, trends in risk factor control, preventive care, disparities, and current unmet needs, particularly in atherosclerotic cardiovascular disease management in Singapore.

Study on the diffusion and deposition law of pore slurry in gangue filling zone based on CFD-DEM coupling.

In this study, the slurry diffusion in a cavity filled with coal gangue was studied by combining experimental and numerical simulation methods. By calibrating slurry and particle materials, the grouting process in coal gangue filling area is simulated successfully, and the change of slurry diffusion flow field and particle movement and settling process in different dimensions are deeply analyzed. Both experimental and numerical simulation results show that the particle settlement presents a bell-shaped curve, which is of great significance for understanding the particle movement and settlement behavior in the filling cavity. In addition, it is found that the grouting speed has a significant effect on the particle settlement during the slurry diffusion process. When the grouting speed increases from 0.1m /s to 0.2m /s, the particle settlement and diffusion range increases about twice. In the plane flow field, it is observed that the outward diffusion trend and speed of grouting are more obvious. It is worth noting that in the whole process of grouting, it is observed that with the increase of grouting distance and depth, both the velocity of slurry and particles show a trend of rapid initial decline and gradually slow down, and the flow velocity of slurry near the grouting outlet at a flow rate of 0.2m/s is 2-4 times that of 0.1m/s. This provides important enlightenment for the porous seepage effect at different grouting speeds.

Survival analysis of the duration of rumors during the COVID-19 pandemic.

The emergence of the COVID-19 pandemic towards the end of 2019 triggered a relentless spread of online misinformation, which significantly impacted societal stability, public perception, and the effectiveness of measures to prevent and control the epidemic. Understanding the complex dynamics and characteristics that determine the duration of rumors is crucial for their effective management. In response to this urgent requirement, our study takes survival analysis method to analyze COVID-19 rumors comprehensively and rigorously. Our primary aim is to clarify the distribution patterns and key determinants of their persistence. Through this exploration, we aim to contribute to the development of robust rumor management strategies, thereby reducing the adverse effects of misinformation during the ongoing pandemic. The dataset utilized in this research was sourced from Tencent's "Jiao Zhen" Verification Platform's "Real-Time Debunking of Novel Coronavirus Pneumonia" system. We gathered a total of 754 instances of rumors from January 18, 2020, to January 17, 2023. The duration of each rumor was ascertained using the Baidu search engine. To analyze these rumors, survival analysis techniques were applied. The study focused on examining various factors that might influence the rumors' longevity, including the theme of the content, emotional appeal, the credibility of the source, and the mode of presentation. Our study's results indicate that a rumor's lifecycle post-emergence typically progresses through three distinct phases: an initial rapid decline phase (0-25days), followed by a stable phase (25-1000days), and ultimately, an extinction phase (beyond 1000days). It is observed that half of the rumors fade within the first 25days, with an average duration of approximately 260.15days. When compared to the baseline category of prevention and treatment rumors, the risk of dissipation is markedly higher in other categories: policy measures rumors are 3.58 times more likely to perish, virus information rumors have a 0.52 times higher risk, epidemic situation rumors are 4.86 times more likely to die out, and social current affairs rumors face a 2.02 times increased risk. Additionally, in comparison to wish rumors, bogie rumors and aggression rumors have 0.26 and 0.27 times higher risks of dying, respectively. In terms of presentation, graphical and video rumors share similar dissolution risks, whereas textual rumors tend to have a longer survival time. Interestingly, the credibility of the rumor's source does not significantly impact its longevity. The survival time of rumors is strongly linked to their content theme and emotional appeal, whereas the credibility of the source and the format of presentation have a more auxiliary influence. This study recommends that government agencies should adopt specific strategies to counter rumors. Experts and scholars are encouraged to take an active role in spreading health knowledge. It's important for the public to proactively seek trustworthy sources for accurate information. Media platforms are advised to maintain journalistic integrity, verify the accuracy of information, and guide the public towards improved media literacy. These actions, collectively, can foster a collaborative alliance between the government and the media, effectively combating misinformation.

Basalt fibre degradation in seawater and consequences for long term composite reinforcement

Basalt fibres are increasingly employed as reinforcements in marine composites, but their behaviour in natural marine environments is underexplored. This study investigates basalt fibre ageing in renewed natural seawater at 15 °C and 40 °C. After one month in seawater at 15 °C and 40 °C, tensile strength dropped, stabilizing at approximately −40% and −60%, respectively. This rapid initial property decline, followed by slower degradation, is attributed to an altered surface layer on the fibres. Initially causing significant property loss, this layer then plays a protective role, preserving the fibre core. The impact on basalt/epoxy composites exposed to 7.5 years of seawater was less severe, with a 20% loss at 40 °C, demonstrating the protective function of the matrix. This study suggests that basalt fibres undergo rapid, then stable, property degradation in water, but remain suitable for use as epoxy matrix composite reinforcements, thanks to the protective role of the resin.

Experimental investigation on shear strength deterioration at the interface between different rock types under cyclic loading

The shear strength deterioration of bedding planes between different rock types induced by cyclic loading is vital to reasonably evaluate the stability of soft and hard interbedded bedding rock slopes under earthquake; however, rare work has been devoted to this subject due to lack of attention. In this study, experimental investigations on shear strength weakening of discontinuities with different joint wall material (DDJM) under cyclic loading were conducted by taking the interface between siltstone and mudstone in the Shaba slope of Yunnan Province, China as research objects. A total of 99 pairs of similar material samples of DDJM (81 pairs) and discontinuities with identical joint wall material (DIJM) (18 pairs) were fabricated by inserting plates, engraved with typical surface morphology obtained by performing three-dimensional laser scanning on natural DDJMs sampled from field, into mold boxes. Cyclic shear tests were conducted on these samples to study their shear strength changes with the cyclic number considering the effects of normal stress, joint surface morphology, shear displacement amplitude and shear rate. The results indicate that the shear stress vs. shear displacement curves under each shear cycle and the peak shear strength vs. cyclic number curves of the studied DDJMs are between those of DIJMs with siltstone and mudstone, while closer to those of DIJMs with mudstone. The peak shear strengths of DDJMs exhibit an initial rapid decline followed by a gradual decrease with the cyclic number and the decrease rate varies from 6% to 55.9% for samples with varied surface morphology under different testing conditions. The normal stress, joint surface morphology, shear displacement amplitude and shear rate collectively influence the shear strength deterioration of DDJM under cyclic shear loading, with the degree of influence being greater for larger normal stress, rougher surface morphology, larger shear displacement amplitude and faster shear rate.

Experimental study on resistivity evolution law and precursory signals in the damage process of gas-bearing coal

The occurrence of elevated gas pressure leads to the distortion of the internal pore structure within the coal matrix, thereby exerting a substantial influence on the destabilization of the coal body. This disturbance further contributes to intricate changes in coal resistivity. To delve into the process of gas-induced damage and its implications for coal resistivity, this research employs nuclear magnetic resonance (NMR) technology as a means to characterize coal samples. Moreover, a controlled loading experimental equipment is devised for gas-bearing coal, while concurrently gathering data on resistivity and acoustic emission (AE). The result shows that with increasing applied stress, the change in resistivity within gas-bearing coal exhibits a progressive intensification, manifesting a notable “V”-shaped pattern. This pattern is characterized by an initial rapid decline, succeeded by a subsequent swift increase during the failure stage. The AE signals exhibit a synchronized consistency with the observed resistivity change. With increasing gas pressure, the coal's resistivity exhibits heightened fluctuations, and notably, the range of resistivity at failure under a pressure of 3 MPa is 2.27 times greater compared to that at 0 MPa. Furthermore, the damage variable and constitutive equation for gas-bearing coal based on resistivity is established. The critical value for damage (DE) occurs 1.75 s before the critical value of the resistivity change rate, and 3.88 s earlier than the actual occurrence of damage in the coal body. The correlation between the verified damage and measured stress exceeds 0.8, demonstrating a strong correlation at different stages. The research results contribute to understanding the evolution mechanism of gas instability and hold considerable significance for preventing coal and gas outburst disasters.

Experimental study on reducing water hammer effects in uPVC pipes using rubber bypass tubes

Applying bypass (parallel) flexible tubes made of rubber was studied for the first time, affixed on an uPVC pipeline upstream of a regulation valve, to mitigate water hammer effects by employing simple and readily available tools. Ninety-two experiments were conducted to analyze the influence of the flexible tubes' elasticity Modulus, lengths, and inner volumes. The results demonstrate that implementing bypass rubber tubes substantially reduces the head rise (ΔH), even for shorter tube lengths. The reduction rate of ΔH shows an initial rapid decline followed by a gradual decrease as the tube length increases. Besides, the bypass rubber tube utilization significantly reduced the hammer celerity and increased both the water hammer's characteristic time and the damping rate of the hammer. The elasticity Modulus of the rubber tube exhibits a significant effect on ΔH, displaying a reverse relationship. Finally, ΔH decreases as the inner volume of the rubber tubes increases.

Mineralization mechanism of organic carbon in maize rhizosphere soil of soft rock and sand mixed soil under different fertilization modes.

This article endeavors to investigate the influence of various fertilization methods on the characteristics of rhizosphere soil and organic carbon mineralization in the mixed soil of Mu Us Sandy land under maize cultivation, with the objective of laying the groundwork for low-carbon agriculture and the development of high-quality farmland. The research focuses on soft rock and sand composite soil with a 1:2 ratio, and it comprises four treatments: no fertilization (CK), only chemical fertilization (CF), only cattle manure application (MF), and only oil residue application (DF). The findings revealed that the use of organic fertilizer substantially elevated nutrient content and enzyme activity in the maize rhizosphere soil. Furthermore, it had a notable influence on both soil aggregate diameter and stability. Specifically, the DF treatment led to a significant increase in both soil aggregate diameter and stability. The mineralization rate of organic carbon in the maize rhizosphere soil could be categorized into two distinct phases: a rapid initial decline followed by a slower release. By the end of the incubation period, the cumulative mineralization of organic carbon in the MF, DF, and CF treatments showed a significant increase of 119.87%, 57.57%, and 24.15%, respectively, in comparison to the CK treatment. Additionally, the mineralization rate constants of the DF and MF treatments experienced a substantial rise, with increments of 23.52% and 45.97%, respectively, when contrasted with the CK treatment. The bacterial phyla Actinobacteriota, Proteobacteria, Chloroflexi, Acidobacteriota, and Firmicutes were dominant in the rhizosphere soil bacterial community. Specific genera such as Nocardioides and Sphingomonas showed significant correlations with organic carbon mineralization. The application of different organic fertilizer can improve soil physical, chemical and biological properties, and promote the mineralization process of organic carbon in maize rhizosphere soil. Notably, the DF treatment exhibited the most favorable outcome, improving the overall quality of maize rhizosphere soil while incurring a minimal loss of unit organic carbon. These findings hold significant implications for optimizing field management practices and augmenting soil quality.

SN 2020bio: A Double-peaked, H-poor Type IIb Supernova with Evidence of Circumstellar Interaction

We present photometric and spectroscopic observations of SN 2020bio, a double-peaked Type IIb supernova (SN) discovered within a day of explosion, primarily obtained by Las Cumbres Observatory and Swift. SN 2020bio displays a rapid and long-lasting initial decline throughout the first week of its light curve, similarly to other well-studied Type IIb SNe. This early-time emission is thought to originate from the cooling of the extended outer hydrogen-rich (H-rich) envelope of the progenitor star that is shock heated by the SN explosion. We compare SN 2020bio to a sample of other double-peaked Type IIb SNe in order to investigate its progenitor properties. Analytical model fits to the early-time emission give progenitor radius (≈100–1500 R ⊙) and H-rich envelope mass (≈0.01–0.5 M ⊙) estimates that are consistent with other Type IIb SNe. However, SN 2020bio displays several peculiarities, including (1) weak H spectral features indicating a greater amount of mass loss than other Type IIb progenitors; (2) an underluminous secondary light-curve peak that implies a small amount of synthesized 56Ni (M Ni ≈0.02 M ⊙); and (3) low-luminosity nebular [O i] and interaction-powered nebular features. These observations are more consistent with a lower-mass progenitor (M ZAMS ≈ 12 M ⊙) that was stripped of most of its H-rich envelope before exploding. This study adds to the growing diversity in the observed properties of Type IIb SNe and their progenitors.

Study of Estimated Ultimate Recovery Prediction and Multi-Stage Supercharging Technology for Shale Gas Wells

The development of shale gas reservoirs often involves the utilization of horizontal well segmental multi-stage fracturing techniques. However, these reservoirs face challenges, such as rapid initial wellhead pressure and production decline, leading to extended periods of low-pressure production. To address these issues and enhance the production during the low-pressure stage, pressurized mining is considered as an effective measure. Determining the appropriate pressurization target and method for the shale gas wells is of great practical significance for ensuring stable production in shale gas fields. This study takes into account the current development status of shale gas fields and proposes a three-stage pressurization process. The process involves primary supercharging at the center station of the block, secondary supercharging at the gas collecting station, and the introduction of a small booster device located behind the platform separator and in front of the outbound valve group. By incorporating a compressor, the wellhead pressure can be reduced to 0.4 MPa, resulting in a daily output of 12,000 to 14,000 cubic meters from the platform. Using a critical liquid-carrying model for shale gas horizontal wells, this study demonstrates that reducing the wellhead pressure decreases the critical flow of liquid, thereby facilitating the discharge of the accumulated fluid from the gas well. Additionally, the formation pressure of shale gas wells is estimated using the mass balance method. This study calculates the cumulative production of different IPR curves based on the formation pressure. It develops a dynamic production decline model for gas outlet wells and establishes a relationship between the pressure depletion of gas reservoirs and the cumulative gas production before and after pressurization of H10 −2 and H10 −3 wells. The final estimated ultimate recovery of two wells is calculated. In conclusion, the implementation of multi-stage pressurization, as proposed in this study, effectively enhances the production of, and holds practical significance for, stable development of shale gas fields.

Factors leading to the trajectory of cognitive decline in middle-aged and older adults using group-based trajectory modeling: A cohort study.

Currently, studies exploring factors associated with the cognition at some time point and no study identifying the trajectories of cognitive changes and factors might associate with the trajectories of cognitive changes in people. This study was to identify factors associated with the trend of cognitive decline in middle-aged and older people. In this cohort study, the data of 6954 subjects were collected from China Health and Retirement Longitudinal Survey database. Group-based trajectory modeling was applied for identifying three different trajectories of cognitive function change [high initial level and slow decline group (n = 1024), moderate initial level and moderate decline group (n = 2673) and low initial level and rapid decline (LRD) group (n = 3277)]. Univariate and multivariate logistic regression analysis was conducted to identify variables influencing factors of the trajectories of cognitive function in middle-aged and older people. The follow-up interval was 2 years from 2011 to 2015, and 3 years from 2015 to 2018 via face-to-face interview. High initial level and slow decline group versus LRD group, age (OR = 2.591, 95% CI: 1.962-3.421), gender (OR = 1.398, 95% CI: 1.133-1.725), education (OR = 0.051, 95% CI: 0.039-0.068), place of residence (OR = 2.768, 95% CI: 1.663-4.606), disabled (OR = 1.557, 95% CI: 1.189-2.039), family annual income (OR = 0.757, 95% CI: 0.618-0.929), sleep duration (OR = 1.266, 95% CI: 1.023-1.567), instrumental activity of daily living impairment (OR = 2.513, 95% CI: 1.947-3.245), community activities participation (OR = 0.611, 95% CI: 0.500-0.748), depression (OR = 1.471, 95% CI: 1.185-1.828), and systolic blood pressure (OR = 1.005, 95% CI: 1.001-1.009) were factors influencing the trajectories of cognitive function. Comparing moderate initial level and moderate decline group and LRD group, age (OR = 1.245, 95% CI: 1.052-1.474), gender (OR = 1.244, 95% CI: 1.062-1.458), education (OR = 0.244, 95% CI: 0.190-0.314), marital status (OR = 1.291, 95% CI: 1.079-1.546), place of residence (OR = 1.677, 95% CI: 1.358-2.071), disability (OR = 1.396, 95% CI: 1.180-1.652), smoking (OR = 1.249, 95% CI: 1.071-1.457), family annual income (OR = 0.863, 95% CI: 0.768-0.970), sleep duration (OR = 1.215, 95% CI: 0.973-1.541), instrumental activity of daily living impairment (OR = 1.309, 95% CI: 1.098-1.560), community activities participation (OR = 0.804, 95% CI: 0.718-0.900) and depression (OR = 1.383, 95% CI: 1.217-1.571) were factors associated with the trajectories of cognitive function changes. Middle-aged and older adults who had characteristics associated with increased risk of cognitive decline might be provided with timely interventions.

Salt crystal: Natural proppant for enhancing shale reservoir production

Salt crystals can be functioned as the proppant to support the natural fractures of shale reservoirs. It can alleviate the initial rapid production decline of the shale gas wells and solve the problem of the large particle size of the proppant entering into the natural fractures. This study carried out stress-sensitive experiments on salt crystals and proppant with single layer or high-way support, and it reveals the benefit of salt crystals to relieve the stress sensitivity. The microstructure and fracture surface morphology analysis of salt crystals explains that the compressive strength of salt crystals is caused by the structure difference of the supporting systems. An innovative strategy by using proppant to support hydraulic fractures and salt crystals to support natural fractures is suggested for enhancing shale gas production.

Measurements and interpretation of crude Oil-Water/Brine dynamic interfacial tension at subsurface representative conditions

Interfacial tensions (IFTs) between crude oil and water or brine systems are critically important in many processes. Exhibited dynamic behavior often remains poorly studied and requires in-depth analysis. In this study, 27 series of dynamic IFT measurements were conducted for three different crude oils in combination with three different aqueous phases (pure water and two synthetic reservoir brines) at temperatures of 298.15, 343.15 and 393.15 K and pressures up to 30 MPa. This study provides a large database of crude oil-water/brine IFTs encompassing reservoir conditions of temperature and pressure. Specific effects of temperature, pressure, and fluid composition on the crude oil-water and oil-brine IFTs were evaluated. The dynamic evolution of the IFT between the crude oils and aqueous phases was categorized according to typical relationships observed. The most commonly observed evolution was an initial rapid decline in IFT, over a period of 100 to 1,000 s, followed by levelling off at a nearly-constant long-term value. However, in certain cases, the initial rapid decline was followed by a broad minimum and a subsequent slow increase towards a nearly-steady long-time value. In either case, the initial decline is described by a simple model based on diffusion of surface-active components in the oil and their subsequent adsorption at the interface. The longer-term behavior may be further attributed to a combination of saturation, rearrangement and dissolution of the surface-active components.

EXPERIMENTAL STUDY ON THE MECHANICAL PROPERTIES OF ARGILLACEOUS QUARTZ SILTSTONE UNDER DIFFERENT UPPER LIMIT CYCLIC LOADINGS

Cyclic-to-monotonic loading tests and fatigue damage tests were conducted to reveal the deformation characteristics and mechanical properties of argillaceous quartz siltstone under cyclic loading. When the upper limit loading was changed from less than to greater than the fatigue strength, both the axial and lateral cumulative residual strains extended from a monotonically increasing convex curve to a concave curve. The hysteresis loop distance evolved from sparse-dense to sparse-dense-sparse. The residual strain rate and relative area of hysteresis loop was changed from L-shaped to U-shaped. The elastic modulus evolved from three stages of initial rapid rise, decline, and slow and steady development to monotonically decreasing concave curve to convex curve. The lateral-to-axial strain ratio was changed from a monotonically decreasing concave curve to a monotonically increasing convex curve, and then extended to a concave curve. With the increase of the upper limit loading, the rock compressive strength of the argillaceous quartz siltstone was first increased and then decreased after cyclic loading of 3000 times. The maximum value was 13.62% higher than the uniaxial compressive strength. When the upper limit loading was less than the uniaxial elastic limit, the rock compressive strength after the cyclic loading was slightly less than the uniaxial compressive strength. When fatigue failure occurred, the relation between the fatigue life and the upper limit loading exhibited a power function distribution. The fatigue strength was approximately 80%~89% of the uniaxial compressive strength. With the increase of the upper limit loading, the elastic modulus first increased and then decreased, while the lateral-to-axial strain ratio continually increased. The weak structural fracture effect and the compaction effect under cyclic loading on rock are proposed, which can explain the strength characteristics and mechanical parameters evolution law of porous weak cemented rock under cyclic loading.

Long-term behavior of PFAS in contaminated agricultural soils in Germany

Per- and polyfluoroalkyl substances (PFAS) contaminated compost materials have been applied over the last few decades to agricultural fields in Germany, resulting in large-scale diffuse PFAS plumes. The leaching behavior of PFAS from the first two identified contaminated agricultural sites in Germany were investigated, one at Brilon-Scharfenberg, North Rhine-Westphalia (BS-NRW), and the other at Rastatt/Mannheim, Baden-Württemberg. The specific objectives of this study were to assess the longevity of the PFAS agricultural sources and compare standardized column percolation tests to long-term leaching of PFAS from contaminated sites. The advection-dispersion model (ADM) was used to compare the leaching behavior of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) from standardized column percolation tests and long-term field leaching data from the BS-NRW site. Column leaching tests conducted with PFOS and PFOA contaminated soil simulated the initial rapid decline but did not predict the long-term behavior (tailing) observed at the field site over 12 years. Trend analyses of the PFAS field data from the BS-NRW showed that concentrations had stabilized and that individual PFAS exhibited distinct seasonal fluctuations; the latter is likely due to the ongoing transformation of precursors and a seasonal influence on production rates of mobile PFAS. Mass balances conducted at both sites indicate that complete removal of these compounds will likely take years to decades to occur, which is expected from the results of the column leaching tests.

Long-term effects of early antiretroviral initiation on HIV reservoir markers: a longitudinal analysis of the MERLIN clinical study

SummaryBackgroundEarly antiretroviral therapy (ART) initiation (ie, within 3 months of infection) limits establishment of the HIV reservoir. However, the effect of early ART initiation on the long-term dynamics of the pool of infected cells remains unclear.MethodsIn this longitudinal analysis, we included cisgender men who have sex with men (MSM) and transgender women (aged 18–54 years) at high risk for HIV infection, enrolled in the ongoing longitudinal MERLIN study in Peru between Oct 28, 2014, and Nov 8, 2018. Participants were eligible if they had been infected with HIV less than 90 days before enrolment, and if they had cryopreserved peripheral blood mononuclear cell (PBMC) samples. Participants were stratified into three groups on the basis of whether they initiated ART at 30 days or less (acute group), at 31–90 days (early group), or more than 24 weeks (deferred group) after the estimated date of detectable infection. PBMC samples were collected before ART initiation and longitudinally for up to 4 years on ART. The main outcomes were to establish the size of the HIV reservoir before ART initiation and to assess the effect of the timing of ART initiation on the decay of the HIV reservoir over 4 years follow-up. We quantified viral load, and isolated CD4 cells to quantify total HIV DNA, integrated HIV DNA and 2-long terminal repeat circles. Longitudinal analysis of active and inducible HIV reservoirs were measured by quantifying the frequency of CD4 cells producing multiply-spliced HIV RNA ex vivo and after in-vitro stimulation with a tat/rev induced limiting dilution assay (TILDA). A mixed-effects model from the time of ART initiation was used to measure longitudinal decays in viral loads and each HIV reservoir measure in each of the three groups.FindingsWe included 56 participants in this analysis, all of whom were MSM: 15 were in the acute group, 19 were in the early group, and 22 were in the deferred group. Participants in all three groups had similar levels of all HIV reservoir markers before ART initiation. All participants, including those in the acute group, had a pool of transcriptionally silent HIV-infected cells before ART initiation, as indicated by a substantial increase in TILDA measures upon stimulation. Longitudinal analysis over 4 years of ART revealed a biphasic decay of all HIV persistence markers, with a rapid initial decline followed by a slower decay in all participants. During the first-phase decay, the half-lives of both total and integrated HIV DNA and TILDA measures were significantly shorter in the acute group than in the early and deferred groups. During the second-phase decay, HIV reservoir markers continued to decline only in participants in the acute group.InterpretationParticipants who initiated ART within 30 days or less of HIV infection showed a steeper and more sustained decay in HIV reservoir measures, suggesting long-term benefit of acute ART initiation on reservoir clearance.FundingThe US National Institutes of Health and the Canadian Institutes for Health Research.