bluuebunny/crossref_metadata_2025 huggingface dataset:
China’s geothermal resources development status, problems and suggestions under the background of carbon neutrality
Authors: Shen L , Liu L
Published: June 2021

The development and utilization of geothermal resources is of great significance to China’s goal of carbon neutrality. Based on the research results of predecessors, through systematic analysis and summary, this paper shows the current research status of geothermal resources (including the utilization of geothermal energy, output characteristics and distribution rules, and classification of geothermal energy) and existing problems (such as unclear understanding of the geothermal formation mode, low survey accuracy and weak basic geothermal geological survey work). Finally, in response to the above-mentioned problems, some countermeasures and suggestions are put forward for the research of China’s geothermal resources in the context of carbon neutrality, such as further strengthening policy support and geothermal resource management; reinforcing basic geological surveys and expand geothermal reserve resources, promoting the integration of professional and intelligent monitoring station networks.
Study on Ultrasonic-assisted Water Extraction of Polysaccharides from Sunflower Tray
Authors: Fei Yingmin , Liu Xinci , Zhang Gensheng
Published: June 2021

Sunflower tray has been widely studied in recent years because of its rich polysaccharide. In this study, sunflower tray powder was used as raw materialto optimizing the process parameters of ultrasonic-assisted extraction of polysaccharides. Single-factor experiments were used to explore the effects of material-liquid ratio, ultrasonic temperature, ultrasonic time and ultrasonic power on the extraction rate of polysaccharides; response surface experiments were used to optimize the process parameters for the optimal polysaccharide extraction rate. The experimental results show that: the ratio of material to liquid is 1:37, the ultrasonic temperature is 52.50°C, and the ultrasonic time is 31min, the ultrasonic power is 300W. Extracted twice under this condition, the yield of sunflower tray polysaccharide reached 10.15%, the polysaccharide extraction process is reproducible and stable.
Research on Effectiveness Assessment of Ecological Conservation in Xinjiang Based on the Cloud Model
Authors: Ke Yin , Linsheng Jiang , Jimin Chen
Published: June 2021

Aiming for effective ecological conservation in Xinjiang, an effectiveness assessment system is built on the cloud model to examine the controllability of ecological conservation based on the practice in Xinjiang. It has been found that the cloud model for effectiveness assessment fully takes into account ambiguity and randomness where the expert review falls short and can effectively improve the influence of subjective factors in the assessment of ecological conservation through parameter setting and calculation. Therefore, it leads to accurate and practical assessment results. These findings can play an important referential role in improving the practicality and effectiveness of ecological conservation in Xinjiang.
Screening of imbibition surfactant in inter-salt shale reservoir
Authors: Li Fengxia , Wang Haibo , Tang Jiandong , Shen Yunqi , Wang Di
Published: June 2021

Under the current environment of low oil price, surfactant enhanced oil recovery technology is more economic and feasible without changing fracturing technology and adding special equipment. Surfactant enhanced oil recovery is induced by decreasing interfacial tension and changing wettability. However, there are many kinds of surfactant, and the reservoir conditions and rock types are different, so the first requirement of enhanced oil recovery is to select the surfactant which is suitable for the target reservoir. In view of the characteristics of high temperature and high salinity in inter-salt shale reservoir, in this paper, several surfactant types were selected and negative/non-composite surfactants were screened out by taking the adhesion work reduction factor related to imbibition resistance as the main index. This study is of practical significance for hydraulic fracturing reservoirs with surfactant enhanced oil recovery technology.
Technologies selection to prevent and control excrement pollution from livestock and poultry farming in Huang-Huai-Hai Region
Authors: Du Zhiwei , Liu Yuexian , Zhang Ruili , Wu Yu
Published: June 2021

Taking nitrogen, phosphorus, heavy metals and antibiotics as selection indicators, the fuzzy matter element analysis based on the entropy weight method was used to evaluate and select the technologies to prevent and control excrement pollution from intensive livestock and poultry farming in the Huang-Huai-Hai (HHH) Region, with the combination of Euclid approach degree. The results showed that the N change rate and the passivation rate of heavy metals in the excrement pollution treatment technologies accounted for higher weights, indicating that the difference between N and heavy metals in different treatment technologies was large. When choosing treatment technology, priority could be given to the technologies to prevent and control N and heavy metals. According to the final evaluation results, the technology of multi-level ecological and in-depth treatment was better for the liquid manure, while the technology of reactor composting was better for the treatment of solid manure.
Emergency gate closing in a Kaplan turbine intake for runaway condition: CFD transient study for two-phase flow and experimental validation
Authors: Rivetti A , Angarita G , Angulo M , Botero F , Liscia S
Published: June 2021

In order to prevent a turbine to reach its runaway speed when load rejection occurs, an emergency closing system must be devised in case the regulation system fails. For Kaplan turbines, fixed wheel gates located in the turbine intake or in the draft tube outlet are usually employed. Gates of this type are move by gravity and the closing velocity is controlled by gantry cranes. The closing maneuver is complex due to the high flow rates inherent to runaway conditions and the rotational deceleration during the gate’s closing time. Research on this topic is scarce and limited, and numerical studies are usually clouded by uncertainties concerning the setting of proper boundary conditions. In this work, the closing maneuver of the emergency fixed wheel gates at the intake of a Kaplan turbine was studied with CFD two-phase transient simulation. The software used was ANSYS CFX, that solves unsteady Navier-Stokes equations (URANS) by means of the finite volume method. The simulated domain includes a 2D case from one of the span of the semi-spiral casing and a 3D case of a complete span. Two types of simulation were considered, namely: quasi-steady state, where the position of the gate is fixed; and full transient state, where the gate movement was modelled by an immersed solid model. In search of the optimum model layout with its set of boundary conditions, numerical results were compared and validated against experiments performed on a physical scale model in accordance with IEC 60193 norms for several turbulence models. Results show that the pull-up force on the gate increases as it is being closed. Analysis of pressure fluctuation at different points of the gate suggest that the main frequency component is the vortex shedding of the gate lip.
Numerical simulation prediction of pressure distribution of guide vanes in a high-head pump turbine
Authors: He Lei , Gao Zhongxin , Chen Ying , Zhang Jianguang , Ma Bingquan , Meng Xiaochao , Rao Lei
Published: June 2021

In order to clarify the influence of different turbulence models on the numerical simulation of the pump turbine, 3D numerical steady simulations using four kinds of turbulence models: SST, k-ε, k-ω and RNG k-ε were applied to simulate the flow inside the mixed-flow pump turbine. 16 monitoring points were installed in guide vanes to obtain the relationship between pressure distribution of guide vanes in different monitoring locations and operation conditions. The pressure distribution of guide vanes was simulated using four kinds of turbulence models, and compared with the model test results. The results show that when the turbulence model is SST, the numerical simulation results are closer to the model test results.
Opening sequence optimization for La Coche pumps back-to-back start-up through electrically coupled Pelton unit.
Authors: Andolfatto Loïc , Rentschler Martin , Haeussler Walter , Gervais Nicolas
Published: June 2021

La Coche pumped storage power plant features 4 pump-turbine units and a Pelton unit, with the possibility for direct full frequency electrical coupling of the Pelton unit generator with the pump turbine motors. The back-to-back start-up mode consists in reaching synchronous speed of both pump unit and turbine unit by using the hydraulic power delivered to the turbine, without requiring absorbed electrical power peak usually perturbing the grid during pump start-up.

The fastest start-up is achieved while the hydraulic power injected in the system is maximized. The associated risk lies in reaching levels of mechanical load of the Pelton runner that dramatically reduce the runner remaining lifetime at each start-up.

The proposed work focus on the Pelton turbine nozzle opening law optimization to minimize the start-up time, while keeping the level of stress in the Pelton runner below a maximum allowed value. Numerical simulations coupling CFD and FEM were associated to train a surrogate model predicting the runner condition along the transient start-up sequence. Resolution of the first order differential equation of the coupled units start-up trajectory under boundary conditions defined from nozzle opening sequence allowed to assess both associated start-up time and stress levels.

Results of the field measurement gathered during the commissioning phase were compared to simulation results to update the implemented model parameters and optimize the start-up sequence allowing fast and long lasting back-to-back start-up capacity.
CFD simulation of the pump trip runaway transient process of a pumped-storage power plant with head 700 m
Authors: Yang Z Y , Zhang X X , Liu D M , Cheng Y G , Zhao M D
Published: June 2021

Simulating transient processes of pumped-storage power plants is essential for the design and optimization of pump-turbine and water conveyance system. Because pressure pulsations and runner forces cannot be obtained from the traditional 1D transient simulation methods, 3D CFD simulations are necessary. In this study, the fast runaway transient process, occurring after the pump trip of a pumped-storage plant with a head of 700m, was simulated by using the CFD method that couples the 1D water conveyance system and 3D turbine. The phenomena, composed of water hammer fluctuations, pressure pulsation transitions, and flow pattern evolutions, were described and analyzed. We found that the flow patterns and pressure pulsations change violently as the working point goes through different regions. Especially, the pressure pulsations and unbalanced radial runner forces are the most severe in the S-shaped characteristic region. The strong impact on blades, large scale recirculating vortices in blade passages, obvious rotating stalls in vane and blade regions, transitional backflows at runner inlet and outlet, and strong circumferential velocity in vaneless space are the main sources. The dynamic working trajectory does not follow the measured static characteristic curve and demonstrates an undamped loop in the S-shaped region. This paper provides some evidence on the relations between flow structure and pressure pulsation features, although the mechanism of dynamic characteristics needs further investigations.
Evolution of discharge and runner rotation speed along no-load curves of Francis turbines
Authors: Fortin M , Nennemann B , Deschênes C , Houde S
Published: June 2021

In hydraulic turbines, no-load operation is among the most damaging conditions since unextracted swirl leads to the creation of highly energetic flow structures causing high pressure and strain fluctuations on the turbine components. To date, experimental and numerical studies typically focus on flow characteristics for a specific no-load condition of a specific turbine. However, for a given turbine, a unique no-load condition exists for every single guide vane opening, forming what is called a no-load curve. Few studies describe the evolution of engineering quantities such as discharge and speed along the no-load curve even if those quantities may highlight trends in no-load behavior that can be used to tailor numerical simulations according to specific flow conditions. This paper presents results from a project underway at Andritz Hydro Canada Inc., in collaboration with Université Laval, to analyze the extensive database of experimental no-load tests performed at model scale in order to identify the evolution of discharge and runner rotation speed following the guide vane opening.
Reimagining educational equity through strategic alliance partnerships in response to the USA STEM-M diversity gap
Authors: Rocha Janet , Castillo-Lavergne Claudia M , Byrd Marcus J , Carnethon Mercedes R , Miller Rebecca , Lin Maria , Marsh Erica E , Jackson Janice K , Yancy Clyde W
Published: June 2021

Addressing the USA diversity gap in science, technology, engineering, mathematics and medicine (STEM-M) through strategic alliance partnerships (SAPs) is an innovative solution toward combating the educational inequalities presented in K-12 education for marginalized youth interested in STEM-M professions. We present a model that unites multiple stakeholder s committed to diversifying the workforce in STEM-M, through the implementation of a multi-year high school pipeline program designed to better achieve STEM-M equity, access and opportunity at the secondary school level. We developed a unique model based on an SAP in a large metropolitan area in the Midwest that joins an Academic Medical Center and a local Public High School. Our results involving 46 students over 8 years demonstrate 100% high school graduation rates; 97% college attendance with full or partial scholarship support, and early evidence of post-graduation aspirations in STEM-M careers. Our early progress calls for more rigorous study against standard educational practices. If our program is proven to be more effective, then potentially more strategic public−private partnerships to foster K-12 pipeline programs to better achieve equity through educational access, opportunities and resources should be developed and targeted for those marginalized youth that have been historically denied STEM-M opportunities. After 10 years of dedicated effort, we see evidence of potential benefits of this SAP to develop K-12 pipeline programs with similar aims of STEM-M diversification, particularly by way of more-equitable provision of educational opportunities to students belonging to minority racial and ethnic groups.
IL-23RVariant rs11805303 Is Associated With Susceptibility to the Development of Cutaneous Leishmaniasis inLeishmania guyanensis–Infected Individuals
Authors: Santos da Silva Lener , Santo Júnior José do Espírito , de Mesquita Tirza Gabrielle Ramos , Santos Veronica Alice Marinho , de Souza Josué Lacerda , de Araújo Felipe Jules , da Silveira Júnior Cláudio Marcello , da Silva Cilana Chagas , Queiroz Krys Layane Guimarães Duarte , Sequera Héctor David Graterol , Guerra Marcus Vinitius de Farias , de Souza Mara Lúcia Gomes , Ramasawmy Rajendranath
Published: June 2021

Background

Emerging evidence suggests that the interleukin (IL) 17/ IL-23 axis may play a role in the pathogenesis of leishmaniasis. Our aim was to investigate whether the IL-23R variant rs11805303 is a risk factor for the development of cutaneous leishmaniasis (CL) in Leishmania guyanensis–infected individuals.

Methods

We genotyped by polymerase chain reaction–restriction fragment length polymorphism the rs11805303 C/T in 828 patients with CL and 806 healthy individuals. Plasma tumor necrosis factor–α, IL-6, interferon-γ, IL-1β, and IL-17 were measured with the Bioplex assay.

Results

The distribution of the genotypes differed between patients with CL and healthy controls with a common odds ratio of 1.78 (P = 2.2 × 10–11) for the disease-associated T allele. Leishmania guyanensis–infected individuals homozygous for the T allele show a 200% increased risk of progressing to disease development, with a 95% confidence interval ranging from 81% to 400% (P = 9.9 × 10–6) in comparison to individuals homozygous for the C allele. Males homozygous for the T allele have higher plasma levels of IL-17 compared with heterozygous or homozygous CC individuals.

Conclusions

The present association of the IL-23R variant rs11805303 with the development of CL suggests that the IL-17/IL-23 axis may play an important role in the pathogenesis of CL.
Genetic Evidence for a Potential Environmental Pathway to Spillover Infection of Rat-Borne Leptospirosis
Authors: Casanovas-Massana Arnau , de Oliveira Daiana , Schneider Andrew G , Begon Mike , Childs James E , Costa Federico , Reis Mitermayer G , Ko Albert I , Wunder Elsio A
Published: June 2021

In this study, we genotyped samples from environmental reservoirs (surface water and soil), colonized rat specimens, and cases of human severe leptospirosis from an endemic urban slum in Brazil, to determine the molecular epidemiology of pathogenic Leptospira and identify pathways of leptospirosis infection. We identified a well-established population of Leptospira interrogans serovar Copenhageni common to human leptospirosis cases, and animal and environmental reservoirs. This finding provides genetic evidence for a potential environmental spillover pathway for rat-borne leptospirosis through the environment in this urban community and highlights the importance of environmental and social interventions to reduce spillover infections.
Assessing the impact of clinical pharmacy services on the healthcare outcomes of patients attending an outpatient haemodialysis unit in a rural hospital in Egypt: a quasi-experimental study
Authors: Nagib Reem , Abdul-Latif Maha , Sakoury Hoda S , Elrggal Mahmoud E , Cheema Ejaz , Elnaem Mohamed Hassan , El-Fass Karim A
Published: June 2021

Objectives

This study aimed to investigate the impact of newly introduced clinical pharmacy services on the health care of chronic haemodialysis patients attending an outpatient haemodialysis unit in a rural hospital with limited resources in Alexandria, Egypt.

Methods

A quasi-experimental pre-/post-test study was conducted from November 2016 till June 2018. Clinical pharmacists collected relevant information using a pre-specified form. Patients’ data were reviewed for drug-related problems (DRPs), which were documented using the Pharmaceutical Care Network Europe (PCNE) classification system, version 8.02 and resolved by the clinical pharmacists. Measured values of calcium, phosphorus and haemoglobin were compared with target levels set by the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines. Proportions of patients achieving therapeutic values of each parameter were compared before and after implementing the program using the McNemar test. We also reported the analysis of DRPs identified and addressed by the clinical pharmacy team.

Key findings

A total of 685 DRPs were identified during the follow-up period. Improper dose and inappropriate drug selection were the most common DRPs (45.8% and 18.9%, respectively). There was a statistically significant increase in the proportion of patients achieving target corrected calcium levels (30% pre-intervention versus 69.6% post-intervention, P = 0.001) and haemoglobin levels (9.1% pre-intervention versus 31.9% post-intervention, P = 0.003), but not in phosphorus levels (18.6% pre-intervention versus 22% post-intervention, P = 0.7).

Conclusions

Clinical pharmacists were able to resolve frequent DRPs and improve some markers of health care in haemodialysis patients.
Deadly Rumors: Lynching, Hearsay, and Hierarchies of Credibility in Mexico
Authors: Kloppe-SantamarÍa Gema
Published: June 2021

This article examines the role of rumors in the collectivization of violence in twentieth-century Mexico. By focusing on a series of cases of lynching driven by rumors of child theft and the stealing of children’s bodily fluids and organs, the article reveals the hierarchies of credibility that make rumors an effective tool to trigger and escalate violence. The article’s main argument is that rumors become deadly or “weaponized” in the form of lynchings in contexts where anxieties and fears regarding processes of modernization and economic exploitation intersect with citizens’ perception of the state as unable or unwilling to provide security and justice. In twentieth-century Mexico, what made rumors vectors of lethal violence was not only a context of collective fear and economic uncertainty, but also their credibility vis-à-vis other forms of knowledge. Such credibility was grounded on citizens’ keen sense of distrust in state authorities and on people’s belief that without recourse to lynching, crimes would go unpunished. Adding to the credibility of these rumors was also the lynched victim’s actual or perceived condition as foreign or external to the community where the lynching took place, a condition that made them more likely to be the subject of rumors involving the extraction and exploitation of local resources. Child-theft rumors occupy a central place in Mexico’s contemporary context of insecurity. This article provides a historical reflection on the connections between hearsay, mob violence, and citizens’ long-term experiences of exploitation, state neglect, and impunity.
The role of atmospheric outflows in the migration of hot Jupiters
Authors: Kurbatov E P , Bisikalo D V
Published: June 2021

Many of observed hot Jupiters are subject to atmospheric outflows. Numerical simulations have shown that the matter escaping from the atmosphere can accumulate outside the orbit of the planet, forming a torus. In a few 108 yr, the mass of the torus can become large enough to exert a significant gravitational effect on the planet. Accumulation of mass, in its own turn, is hindered by the activity of the star, which leads to the photoevaporation of the torus matter. We explore the role of these and other factors in the planet’s migration in the epoch when the protoplanetary disc has already disappeared. Using HD 209458 system as an example, we show that the gravitational interaction with the torus leads to the possibility of migration of the planet to its observable position, starting from an orbit ≳0.3 au.
Peculiar velocity estimation from kinetic SZ effect using deep neural networks
Authors: Wang Yuyu , Ramachandra Nesar , Salazar-Canizales Edgar M , Feldman Hume A , Watkins Richard , Dolag Klaus
Published: June 2021

The Sunyaev–Zel’dolvich (SZ) effect is expected to be instrumental in measuring velocities of distant clusters in near future telescope surveys. We simplify the calculation of peculiar velocities of galaxy clusters using deep learning frameworks trained on numerical simulations to avoid the independent estimation of the optical depth. Images of distorted photon backgrounds are generated for idealized observations using one of the largest cosmological hydrodynamical simulations, the Magneticum simulations. The model is tested to determine its ability of estimating peculiar velocities from future kinetic SZ observations under different noise conditions. The deep learning algorithm displays robustness in estimating peculiar velocities from kinetic SZ effect by an improvement in accuracy of about 17 per cent compared to the analytical approach.
Does jackknife scale really matter for accurate large-scale structure covariances?
Authors: Favole Ginevra , Granett Benjamin R , Silva Lafaurie Javier , Sapone Domenico
Published: June 2021

The jackknife method gives an internal covariance estimate for large-scale structure surveys and allows model-independent errors on cosmological parameters. Using the SDSS-III BOSS CMASS sample, we study how the jackknife size and number of resamplings impact the precision of the covariance estimate on the correlation function multipoles and the error on the inferred baryon acoustic scale. We compare the measurement with the MultiDark Patchy mock galaxy catalogues, and we also validate it against a set of lognormal mocks with the same survey geometry. We build several jackknife configurations that vary in size and number of resamplings. We introduce the Hartlap factor in the covariance estimate that depends on the number of jackknife resamplings. We also find that it is useful to apply the tapering scheme to estimate the precision matrix from a limited number of resamplings. The results from CMASS and mock catalogues show that the error estimate of the baryon acoustic scale does not depend on the jackknife scale. For the shift parameter α, we find an average error of 1.6 per cent, 2.2 per cent and 1.2 per cent, respectively, from CMASS, Patchy, and lognormal jackknife covariances. Despite these uncertainties fluctuate significantly due to some structural limitations of the jackknife method, our α estimates are in reasonable agreement with published pre-reconstruction analyses. Jackknife methods will provide valuable and complementary covariance estimates for future large-scale structure surveys.
Stabilization of Hfq-mediated translational repression by the co-repressor Crc in Pseudomonas aeruginosa
Authors: Malecka Ewelina M , Bassani Flavia , Dendooven Tom , Sonnleitner Elisabeth , Rozner Marlena , Albanese Tanino G , Resch Armin , Luisi Ben , Woodson Sarah , Bläsi Udo
Published: June 2021

In Pseudomonas aeruginosa the RNA chaperone Hfq and the catabolite repression control protein (Crc) govern translation of numerous transcripts during carbon catabolite repression. Here, Crc was shown to enhance Hfq-mediated translational repression of several mRNAs. We have developed a single-molecule fluorescence assay to quantitatively assess the cooperation of Hfq and Crc to form a repressive complex on a RNA, encompassing the translation initiation region and the proximal coding sequence of the P. aeruginosa amiE gene. The presence of Crc did not change the amiE RNA-Hfq interaction lifetimes, whereas it changed the equilibrium towards more stable repressive complexes. This observation is in accord with Cryo-EM analyses, which showed an increased compactness of the repressive Hfq/Crc/RNA assemblies. These biophysical studies revealed how Crc protein kinetically stabilizes Hfq/RNA complexes, and how the two proteins together fold a large segment of the mRNA into a more compact translationally repressive structure. In fact, the presence of Crc resulted in stronger translational repression in vitro and in a significantly reduced half-life of the target amiE mRNA in vivo. Although Hfq is well-known to act with small regulatory RNAs, this study shows how Hfq can collaborate with another protein to down-regulate translation of mRNAs that become targets for the degradative machinery.
The Impact of Instrumentation and Implant Surface Technology on Cervical and Thoracolumbar Fusion
Authors: Wang Timothy Y , Mehta Vikram A , Sankey Eric W , Shaffrey Christopher I , Abd-El-Barr Muhammad M , Than Khoi D
Published: June 2021

Spinal fusion has undergone significant evolution and improvement over the past 50 yr. Historically, spine fusion was noninstrumented and arthrodesis was based entirely on autograft. Improved understanding of spinal anatomy and materials science ushered in a new era of spinal fusion equipped with screw-based technologies and various interbody devices. Osteobiologics is another important realm of spine fusion, and the evolution of various osteobiologics has perhaps undergone the most change within the past 20 yr. A new element to spinal instrumentation has recently gained traction—namely, surface technology. New data suggest that surface treatments play an increasingly well-recognized role in inducing osteogenesis and successful fusion. Until now, however, there has yet to be a unified resource summarizing the existing data and a lack of consensus exists on superior technology. Here, authors provide an in-depth review on surface technology and its impact on spinal arthrodesis.
QuantitativeIn Vitro-to-In VivoExtrapolation for Mixtures: A Case Study of Superfund Priority List Pesticides
Authors: Valdiviezo Alan , Luo Yu-Syuan , Chen Zunwei , Chiu Weihsueh A , Rusyn Ivan
Published: June 2021

In vitro cell-based toxicity testing methods generate large amounts of data informative for risk-based evaluations. To allow extrapolation of the quantitative outputs from cell-based tests to the equivalent exposure levels in humans, reverse toxicokinetic modeling is used to conduct in vitro-to-in vivo extrapolation (IVIVE) from in vitro effective concentrations to in vivo oral dose equivalents. IVIVE modeling approaches for individual chemicals are well-established; however, the potential implications of chemical-to-chemical interactions in mixture settings on IVIVE remain largely unexplored. We hypothesized that chemical coexposures could modulate both protein binding efficiency and hepatocyte clearance of the chemicals in a mixture, which would in turn affect the quantitative IVIVE toxicokinetic parameters. To test this hypothesis, we used 20 pesticides from the Agency for Toxic Substances and Disease Registry Substance Priority List, both individually and as equimolar mixtures, and investigated the concentration-dependent effects of chemical interactions on in vitro toxicokinetic parameters. Plasma protein binding efficiency was determined by using ultracentrifugation, and hepatocyte clearance was estimated in suspensions of cryopreserved primary human hepatocytes. We found that for single chemicals, the protein binding efficiencies were similar at different test concentrations. In a mixture, however, both protein binding efficiency and hepatocyte clearance were affected. When IVIVE was conducted using mixture-derived toxicokinetic data, more conservative estimates of activity-to-exposure ratios were produced as compared with using data from single chemical experiments. Because humans are exposed to mixtures of chemicals, this study is significant as it demonstrates the importance of incorporating mixture-derived parameters into IVIVE for in vitro bioactivity data in order to accurately prioritize risks and facilitate science-based decision-making.
Suppression of Extracellular Signal‐regulated Kinase‐1/2 Causes Fat Accumulation in Hepatocytes: A Potential Mechanism in Alcoholic Fatty Liver Disease (ALD)
Authors: Wang Zhigang , Yao Tong , Song Zhenyuan
Published: June 2021

Although much progress has been made, the underlying mechanism in alcohol‐induced hepatic steatosis is still obscure. In this study, we examined the effect of alcohol exposure on MEK/ERK1/2 activation and its potential involvement in the development of hepatic steatosis. In animal studies, male C57BL/6 mice were pair‐fed with liquid diets containing either ethanol or an isocaloric maltose‐dextrin mixture for four weeks. In the in vitro investigations, HepG2 cells were utilized. Our results showed that chronic alcohol feeding resulted in increased triglyceride accumulation in the liver and liver injury in mice. These observations were concomitant with decreased S‐adenosylmethionine/S‐adenosylhomocysteine ratio and suppressed ERK 1/2 activation in the liver. Using HepG2 cells, we found that ERK inhibition by U0126 elevated intracellular triglyceride contents, and this was associated with increased gene expression of diacylglycerol acyltransferase‐2 (DGAT2). In contrast, epidermal growth factor, a major activator of ERK1/2, reduced triglyceride synthesis. Furthermore, N‐acetyl‐S‐farnesyl‐L‐cysteine (AFC), a methyltrasferase inhibitor, elevated triglyceride synthesis, which is associated with ERK ½ inhibition and enhanced DGAT2 expression. Taken together, our findings suggest that suppression of ERK‐1/2 activation may play a mechanistic role in the development of ALD.

Supported by the National Institutes of Health grants K01 AA015344 and R01 AA017442 (Z Song).
Deficiency in gp91 phox subunit of NADPH oxidase protects against oxidative stress and cardiac dysfunction in iron‐overloaded mice
Authors: Spurney Christopher F. , Kramer Jay H. , Iantorno Micaela , Mak I‐Tong , Chmielinska Joanna J. , Weglicki William B.
Published: June 2021

The role of NADPH oxidase in development of oxidative stress and cardiac dysfunction was assessed using Fe‐overloaded gp91phox (B6.129S6‐Cybbtm1Din/J) knockout (KO) and control (CL: C57BL/6J) mice. Mice were treated 6–8 wks with Fe (2.5 mg/g/wk i.p.)‐ or Na‐dextran; received echocardiography (echo) at 0, 3, & 6 or 8 wks; and plasma 8‐isoprostane levels (lipid peroxidation), cardiac Fe accumulation (Perls’ staining), and CD11b (inflammatory cell infiltrate) were assessed at sacrifice. Fe caused no substantial echo effects at 3 wks; however, significant (p<0.05) declines in LV ejection fraction (18.5% lower vs time‐matched Na‐dextran), fractional shortening (19.7% lower) and heart rate (17.6% lower) occurred in CL at 6 wks, but not in KO. No changes LV mass (no hypertrophy) or mitral value E/A (normal diastolic function) occurred after 6 wks in either strain, and extending Fe to 8 wks had no effects on KO echo values. Six wk Fe‐treated CL displayed substantial cardiac Fe accumulation, 3.2‐fold higher isoprostane, and heightened CD11b; cardiac Fe in KO mice was similar to CL, but lipid peroxidation (50% lower) and CD11b were notably lower in KO, even after 8 wks. Unlike Fe‐treated CL, Gp91phox KO mice were significantly protected against oxidative stress and systolic dysfunction, implicating a deleterious role of NADPH oxidase‐mediated superoxide production (& hydroxyl radical) during Fe overload. NIHRO1‐HL66226.
Near‐Infrared LED Photobiomodulation Attenuates Hypoglycemia‐Induced Cardiotoxicity in a Rodent Model of Diabetes Mellitus
Authors: Gopalakrishnan Sandeep , Wilson Robert , Rakita Jason , Antoniewski Sarah , Abroe Betsy , Snyder Ann , Eells Janis
Published: June 2021

Diabetes‐induced hyperglycemia disrupts mitochondrial energy metabolism and increases oxidative stress. 670 nm light‐emitting diode photobiomodulation (PBM) has been shown to protect mitochondria, attenuate oxidative damage and improve cell survival in experimental and clinical investigations. We tested the hypothesis that 670 nm photobiomodulation would attenuate hypoglycemia‐induced cardiotoxicity in a model of type I diabetes, the streptozotocin (STZ)‐treated rat. Wistar rats were randomly assigned into 3 treatment groups: Control (CON), STZ‐treated (STZ) [50 mg/kg, ip] and 670 nm NIR treated [5 min; 15 J/cm2) STZ‐diabetic rats (NIR). After 98 days of diabetic hyperglycemia animals were euthanized. The heart was harvested, flash frozen and stored at −80 C until analyzed. STZ‐induced diabetes depleted total antioxidants, increased the ratio of oxidized to reduced glutathione, increased nitrotyrosine, decreased catalase, decreased thioredoxin reductase and increased caspase‐3 activity in heart tissue. NIR treatment prevented these cytotoxic actions of STZ. The results support our hypothesis that NIR photobiomodulation attenuates oxidative stress in diabetic cardiomyopathy and suggest that it has therapeutic potential as a cytoprotective strategy for the treatment of diabetes and other chronic degenerative diseases. (RGI [UWM]; BTA [State of Wisconsin]).
Modification of specific amino acid side chains during hydroxyl radical‐dependent bovine serum albumin (BSA) oxidation
Authors: Turrens Julio F , Mott Ashley , Pannell Lewis F , Ruiz Julio C
Published: June 2021

Exposure of proteins to different oxidants is accompanied by light emission from decaying electronically excited intermediates. One of our goals is to identify what amino acid side chains are responsible for this process. In a previous study we showed that exposure of 1mg/ml BSA to 1 mM H2O2/200 μM FeCl2 (a source of hydroxyl radical) resulted in modifications of H42, M111, P120, F251, F353, P596, and M571. In order to determine whether these modifications are random or specific, we repeated the experiment but changed the concentrations of ferrous iron (0, 100 μM and 1 mM), H2O2 (100 μM and 1 mM). Some experiments were run in the presence of ascorbic acid to maintain iron in the reduced state (0.1 mM or 1 mM). The samples were digested and screened through a Q‐Tof Ultima ™ (MS Waters, Micromass, Beverly, MA) at a low flow state of 1 μl/min. Samples that showed proper sample material were sent to the LTQ Orbitrap (Thermo Electron, San Jose, CA) for a reliable and higher resolution search for sequence coverage. Data was analyzed with an in‐house copy of Mascot ™, an internet‐based search engine. The results showed consistent oxidation of specific side chains (F51, C58, H63, F73, F172, F353, M469 and M571). As the concentration of oxidants increased, we observed an increase in non specific modification.

Conclusion

although hydroxyl radical is a very powerful oxidant, it tends to attack specific amino acids in proteins. Another possibility is that these amino acids become associated iron, and therefore become the nearest targets for hydroxyl radicals formed during the decomposition of H2O2.
Caenorhabditis elegans grown on Mn(II) enriched diet have reduced levels of Reactive Oxygen Species (ROS) in vivo
Authors: Rakariyatham Kanyasiri , Villarreal Ponce Alvaro P. , Trinh Kim , Bach Cynthia , Srinivasan Chandra
Published: June 2021

Divalent manganese [Mn(II)] can substitute for superoxide scavenging enzyme(s) in certain unicellular organisms. In a multicellular organism, C. elegans, Mn(II) enriched diet increased this organism's tolerance towards ROS and provided lifespan extension. The molecular basis for the antioxidant‐like activity of Mn(II) is still unclear. To examine whether Mn(II) exerts this activity through the activation of the transcription factor, DAF□16, we utilized three different transgenic strains containing a DAF‐16::GFP fusion, HSP16.2::GFP fusion, and SOD3::GFP fusion. Age synchronized worms were cultivated on normal or Mn(II) supplemented diet and GFP expression was monitored. The nematodes exposed to Mn(II) exhibited a nuclear localization of DAF‐16 as opposed to residing equally between the cytosol and the nucleus under low stress (normal) condition. The expression levels of two downstream targets of DAF‐16, SOD3 and HSP16.2, were higher in worms grown on Mn(II) enriched diet in comparison to untreated controls. In vivo ROS levels measured using a fluorescent dye indicated that the worms grown on Mn(II) enriched diet had reduced levels of ROS. Collectively, our findings suggest that Mn(II) works through the DAF‐16 pathway, which leads to a reduction in ROS levels.
Endothelial Cells from Peroxiredoxin 6 (Prdx6) Null Mice Exhibit Increased Sensitivity to Oxidative Stress and can be used in Rescue Experiments with Wild Type and Mutant Prdx6 Expression Vectors
Authors: LIEN YU‐CHIN , Dodia Chandra , Gao Ling , Feinstein Sheldon I. , Fisher Aron B.
Published: June 2021

Peroxiredoxin 6 (Prdx6) is a bifunctional enzyme enriched in lung, with two active centers, a peroxidase catalyzed by a cysteine at position 47 (C47) and a phospholipase A2 (PLA2) that requires a catalytic triad containing a serine (S32), a histidine (H26) and an aspartate (D140). Our goal is to evaluate the relative importance of each activity in Prdx6‐mediated protection against oxidative stress by examining the effect of mutations in these key amino acids. We exposed endothelial cells isolated from Prdx6 null mice and wild type controls to 200 μM tert‐butyl hydroperoxide (tBuOH) for 24 h. By MTT assay, 90% of the Prdx6 null cells were killed while 80% of the wild‐type cells survived. Expression vectors containing wild‐type or mutant mouse Prdx6 were transfected into approximately 70% of the Prdx6 null cells using Amaxa Nucleofector. Wild type constructs restored PLA2 and phospholipid peroxidase activities. Survival rate after transfection and exposure to 100 μM tBuOH for 24 h were 1% for empty vector increasing to 55% for vector expressing Prdx6 wild type. As predicted, the C47S mutation restored PLA2 activity but not phospholipids hydroperoxide peroxidase activity. The S32A and H26A mutations did not restore either activity, however, D140A did restore a substantial amount of peroxidase activity. These mutants will be tested for their ability to protect endothelial cells from Prdx6 null mice from oxidative damage.
PPARγ Ligands Inhibit Hyperglycemia Induced Endothelial Nox‐4 Expression and Oxidative Stress
Authors: Williams Clintoria Richards , DeShazer Garland , Murphy Tammy , Hart C. Michael
Published: June 2021

Hyperglycemia‐induced oxidative stress is implicated in the pathogenesis of diabetes‐associated vascular diseases. We demonstrated that the expression and activity of NADPH oxidase, was increased in the aortas of diabetic, leptin receptor‐deficient mice and that administration of the PPARγ ligand, rosiglitazone (RSG), reduced the expression of several NADPH oxidase subunits to control levels. In this study, we tested the hypothesis that endothelial NADPH oxidases contribute to hyperglycemia‐induced oxidative stress. Human aortic endothelial cells were treated with normal (5 mmol/L) or high (30 mmol/L) glucose concentrations for 24 – 72 hours. Compared to normal, high glucose increased hydrogen peroxide (H2O2) generation measured with Amplex Red and increased mRNA and protein levels of the H2O2‐generating subunit of NADPH oxidase, Nox‐4. Treatment with either the non‐specific, NADPH oxidase inhibitor, diphenyliodonium (10 μmol/L), or RSG (10 μmol/L) attenuated glucose‐stimulated H2O2 generation. These findings suggest that high glucose concentrations can induce increases in the expression and activity of endothelial Nox‐4 that may contribute to vascular oxidative stress and that ligands for PPARγ may represent a novel target to inhibit NADPH oxidase expression and oxidative stress in the vascular endothelium.

Supported by: The Atlanta VA Research Service and NIH RO1 (DK074518).
Enhanced Oxidative Burst Activity in Macrophages from Obese African American (AA) Women with Metabolic Syndrome (MetS)
Authors: Colden Margaret
Published: June 2021

Obese patients with MetS are at higher risk of atherosclerotic and diabetic complications since they have higher levels of free radicals and a low antioxidant capacity indicating elevated oxidative stress (Skalicky et al., 2008). AA women possess a staggering 57% higher prevalence in having MetS than AA men. To determine if obesity may affect macrophage function in AA women, basal and stimulated oxidative burst activity was measured in peripheral blood‐derived macrophages (PBDMs) from AA women who were lean/insulin‐sensitive (Lean) or obese/insulin‐resistant (Obese) using the fluorescent probe, 2′, 7′‐dichlorofluorescein. Basal oxidative burst activity was similar in Lean and Obese PBDMs compared to control human THP‐1 monocytes. Acute exposure to phorbol ester, PMA (100 nM), stimulated oxidative burst activity by 19% in THP‐1 monocytes. Stimulated oxidative burst activity in Lean PBDMs was enhanced to 317% of basal THP‐1 monocyte activity. Obese PBDMs possessed a significantly higher oxidative burst response to PMA (533% of basal THP‐1 monocytes) compared to Lean PBDMs. These data suggest that macrophage infiltration into adipose tissue may contribute to elevated oxidative stress and development of obesity‐induced inflammation in AA women with MetS. This research was supported by a MSM Center of Research Excellence Career Development Award Proj 5‐04.
Retinoic acid‐induced neuroblastoma differentiation is dependent from NOX activation
Authors: Nitti Mariapaola , Furfaro AnnaLisa , Cevasco Claudia , Balbis Emanuela , Traverso Nicola , Marinari Umberto Maria , Pronzato Maria Adelaide , Domenicotti Cinzia
Published: June 2021

NOX is a multimeric enzyme able to generate superoxide anion as main reaction product. The wide distribution of NOX isoforms in many tissues and cells underlies the role of superoxide anion and reactive oxygen species in cell pathophysiology. In this work, we found that in SH‐SY5Y neuroblastoma cells treated up to 7 days with 10microM retinoic acid (RA) cell differentiation, monitored by cell count, MAP2 expression increase and morphological changes, was accompanied by the up‐regulation of NOX activity, as revealed by regulatory subunit translocation and the overproduction of superoxide anion. Moreover, PKC delta protein level was increased by RA and was involved in NOX activation and in MAP2 induction as shown using siRNA tools.

We suppose NOX involvement in cytoskeleton remodelling during cell differentiation, since the enzyme activity inhibition obtained with DPI exerted a strong preventing effect on cell morphological changes induced by RA. NOX silencing strategy will be applied to confirm these findings.

Grants form Genoa University and MIUR‐PRIN 20077S9A32_002
Actin cytoskeleton remodeling by RhoA and ROCKII regulates vacuolar H+‐ATPase (V‐ATPase) recycling in epididymal clear cells
Authors: Shum Winnie W. C. , Da Silva Nicolas , Belleannee Clemence , Ljubojevic Marija , Hill Eric , Brown Dennis , Breton Sylvie
Published: June 2021

The V‐ATPase in clear cells is important for luminal acidification in the epididymis, a process that is critical for sperm maturation and storage. We demonstrated that proton secretion in these cells is regulated via V‐ATPase recycling. We show here that RhoA and ROCKII are enriched in clear cells, and that a narrow band of cortical F‐actin is located beneath the apical membrane of “resting” clear cells. In epididymis perfused in vivo, agents known to stimulate V‐ATPase membrane accumulation (cpt‐cAMP or cpt‐cGMP) significantly reduced the intensity of the cortical F‐actin staining. The Rho‐Kinase (ROCK) inhibitors Y27632 and HA1077, or the cell permeable Rho inhibitor, Clostridium C3 transferase, also decreased the subapical F‐actin staining and decreased the amount of F‐actin versus G‐actin detected by Western blotting. These agents induced apical membrane V‐ATPase accumulation and elongation of V‐ATPase‐labeled microvilli in clear cells. These results show that actin cytoskeleton depolymerization via inhibition of RhoA or ROCKII favors apical membrane V‐ATPase recruitment. Thus, cAMP‐ or cGMP‐dependent RhoA/ROCKII inhibition might be part of the intracellular signaling cascade that is triggered upon agonist‐induced apical membrane V‐ATPase accumulation and subsequent activation of V‐ATPase‐dependent proton secretion in clear cells. This research is supported by NIH grants DK38452 and HD40793.
Role of AMPK and PKA in the trafficking of V‐ATPase in kidney intercalated cells
Authors: Pastor‐Soler Nuria M. , Gong Fan , Alzamora Rodrigo , Smolak Christy , Thali Ramon , Li Hui , Neumann Dietbert , Hallows Kenneth R.
Published: June 2021

Vacuolar ATPases (V‐ATPase) are expressed at the plasma membrane of type A intercalated cells (ICs) that acidify the lumen of kidney collecting duct. V‐ATPase function is important for acid excretion and defective V‐ATPase in ICs causes metabolic acidosis. V‐ATPase regulation by direct phosphorylation in mammalian epithelial cells is not well characterized. We have shown that in epididymal clear cells V‐ATPase accumulation at the apical membrane is regulated by cAMP/PKA and AMP‐activated kinase (AMPK). We hypothesized that V‐ATPase subcellular localization in ICs depends on phosphorylation of V1 sector subunits and that V‐ATPase regulation is coupled to acid‐base status via PKA and to metabolic status via AMPK. Apical V‐ATPase accumulation in ICs requires cAMP/PKA, as evidenced immunofluorescence labeling of the V‐ATPase in kidney slices treated with various agonists and antagonists. In addition, AMPK activators prevented cAMP/PKA‐mediated V‐ATPase apical accumulation in ICs. Through mass spectrometry, mutagenesis and expression in cultured cells, we have identified several candidate PKA and AMPK phosphorylation sites in V1 sector subunits that may have functional effects on V‐ATPase localization. We propose that subcellular localization and activity of the V‐ATPase in ICs depends on the direct phosphorylation of V1 sector subunits by PKA and AMPK.