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Jackson, T. R., R. Haggerty et S. V. Apte. « A fluid-mechanics-based classification scheme for surface transient storage in riverine environments : quantitatively separating surface from hyporheic transient storage ». Hydrology and Earth System Sciences Discussions 10, no 4 (4 avril 2013) : 4133–206. http://dx.doi.org/10.5194/hessd-10-4133-2013.
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Abstract. Surface transient storage (STS) and hyporheic transient storage (HTS) have functional significance in stream ecology and hydrology. Currently, tracer techniques couple STS and HTS effects on stream nutrient cycling; however, STS resides in localized areas of the surface stream and HTS resides in the hyporheic zone. These contrasting environments result in different storage and exchange mechanisms with the surface stream, which can yield contrasting results when comparing transient storage effects among morphologically diverse streams. We propose a fluid mechanics approach to quantitatively separate STS from HTS that involves classifying and studying different types of STS. As a starting point, a classification scheme is needed. This paper introduces a classification scheme that categorizes different STS in riverine systems based on their flow structure. Eight distinct STS types are identified and some are subcategorized based on characteristic mean flow structure: (1) lateral cavities (emerged and submerged); (2) protruding in-channel flow obstructions (backward- and forward-facing step); (3) isolated in-channel flow obstructions (emerged and submerged); (4) cascades and riffles; (5) aquatic vegetation (emerged and submerged); (6) pools (vertically submerged cavity, closed cavity, and recirculating reservoir); (7) meander bends; and (8) confluence of streams. The long-term goal is to use the classification scheme presented to develop predictive mean residence times for different STS using field-measureable hydromorphic parameters and obtain a theoretical STS residence time distribution (RTD). The STS RTD can then be deconvolved from the transient storage RTD (measured from a tracer test) to obtain an estimate of HTS.
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Zhao, Jiahao, Xiaodan Sun, Dong Wang, Meiquan Wang, Junjie Li, Jun Wang et Qingwei Guan. « Responses of Fine Root Morphological and Chemical Traits among Branch Orders to Forest Thinning in Pinus massoniana Plantations ». Forests 15, no 3 (7 mars 2024) : 495. http://dx.doi.org/10.3390/f15030495.
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Fine roots play an essential role in biogeochemical cycling in forest ecosystems; however, little is known about the response of fine root morphology and chemistry in different root orders to forest management activities such as forest thinning. We investigated the fine root morphological and chemical traits in different root orders of Pinus massoniana under different thinning intensities, namely no thinning, low-intensity thinning (LIT), middle-intensity thinning (MIT), and high-intensity thinning (HIT) (0%, 25%, 45%, and 65% of individual trees eliminated, respectively). We found that forest thinning increased the root diameter (RD) of absorptive roots and decreased that of transport roots, while the trend for the specific root length (SRL) was the opposite. LIT and MIT could increase specific surface area (SSA), especially the SSA of absorptive roots in the MIT treatment. The root tissue density (RTD) of all root sequences in the LIT treatment decreased but increased in the HIT treatment. For the fine root chemical traits, thinning increased the root carbon concentration (RCC) of absorptive roots. The root nitrogen concentration (RNC) and root phosphorus concentration (RPC) of first- to fourth-order roots increased in the LIT and MIT treatments after thinning. Meanwhile, thinning increased root lignin, cellulose, and non-structural carbohydrate (NSC) concentrations. Soil temperature, nitrate, and microbial biomass carbon were factors affecting variations in fine root morphology and chemistry. Forest thinning was likely to shift the absorptive roots’ foraging strategy into a resource-conserving one. Thinning increased fine root chemical traits in most root orders. These findings contributed to our ability to predict how belowground ecological processes are mediated by fine roots under forest management activities.
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Wang, Wenqiang, Wenxiao Wang, Shuang Yu, Hongmei Zhang, Junlong Yang et Xiaowei Li. « Structural Characteristics and Driving Factors of Rhizosphere Microbial Communities in the Rhizosphere of Six Stipa Species Across the Ningxia Steppe ». Sustainability 16, no 23 (24 novembre 2024) : 10273. http://dx.doi.org/10.3390/su162310273.
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The relation and interaction of rhizosphere microbial communities with local environmental factors and root traits is currently a vibrant research hotspot. Yet little is known about how the morphological and functional properties of roots in steppe plants affect microbial community structure. Hence, this study investigated the rhizosphere soil of six Stipa species across the Ningxia steppe in China to examine how the composition of their microbial communities responds to both root traits as well as surrounding environmental factors. Our results reveal significant differences (p < 0.001) in the composition of rhizosphere microbial communities among different Stipa species. The dominant bacterial and fungal phyla are Proteobacteria and Ascomycota, respectively; further, Mortierellomycota plays a key role in the fungal community and is closely associated with other fungal taxa. According to the functional gene predictions for bacteria and fungi, the rhizosphere microbes associated with Stipa species are mainly related to organic matter metabolism and nitrogen cycling. We find that soil physicochemical properties (SOC, TN, TP, AP, SWC, FL, SL) and root traits (RTD, Rtn) are pivotal factors which directly influence the structure of microbial communities dwelling in the rhizosphere of Stipa species. The dominant phyla of fungi and bacteria can respond to those properties in two contrasting ways. One group, consisting of bacteria such as Acidobacteria and fungi like Mortierellomycota, has a relative abundance that is positively correlated with soil nutrients (SOC, TN, AN, TP), whereas the second group, which includes bacteria such as Bacteroidetes and fungi like Ascomycota, is characterized by a negative correlation. More importantly, our results show that root traits significantly impact (p < 0.001) fungal diversity, whereby the morphological and functional properties indirectly affect the composition of bacterial and fungal communities by modulating soil properties. Altogether, the findings suggest that the morphological and functional properties of Stipa roots play a prominent role in shaping the community structure of rhizosphere microbes in steppe, providing a theoretical basis for exploring changes in these communities across space and time, as well as offering insights for grassland conservation and sustainable management.
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Yang, Chao-Hsun, Wan-Ting Kuo, Yun-Ting Chuang, Cheng-Yu Chen et Chih-Chien Lin. « Cyclin B1 Destruction Box-Mediated Protein Instability : The Enhanced Sensitivity of Fluorescent-Protein-Based Reporter Gene System ». BioMed Research International 2013 (2013) : 1–8. http://dx.doi.org/10.1155/2013/732307.
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The periodic expression and destruction of several cyclins are the most important steps for the exact regulation of cell cycle. Cyclins are degraded by the ubiquitin-proteasome system during cell cycle. Besides, a short sequence near the N-terminal of cyclin B called the destruction box (D-box; CDB) is also required. Fluorescent-protein-based reporter gene system is insensitive to analysis because of the overly stable fluorescent proteins. Therefore, in this study, we use human CDB fused with both enhanced green fluorescent protein (EGFP) at C-terminus and red fluorescent protein (RFP, DsRed) at N-terminus in the transfected human melanoma cells to examine the effects of CDB on different fluorescent proteins. Our results indicated that CDB-fused fluorescent protein can be used to examine the slight gene regulations in the reporter gene system and have the potential to be the system for screening of functional compounds in the future.
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Ribeiro, Jéssica Araújo Heringer, Lígia Haira Duarte de Almeida, Thaís Gonzaga de Souza, Pamella Leandra Silva Lima, Sara de Sousa Cardoso, Paulo Henrique Pereira de Souza et Fernando da Costa Brito Lacerda. « Ecosystem importance of roots : A literature review ». Research, Society and Development 13, no 3 (4 mars 2024) : e0313345177. http://dx.doi.org/10.33448/rsd-v13i3.45177.
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Fine roots are all those with a diameter ≤2 mm. These roots are responsible for a significant portion of the primary productivity of terrestrial ecosystems, being important for providing resources to the soil microbial community and for influencing the cycling of carbon and nutrients. Despite their recognized importance, fine roots are commonly neglected in plant biomass studies. Root biomass studies are generally limited throughout the world, mainly due to the methodological complexity involved in the analytical processes. The objective of this work was to carry out a review of studies on the topic of roots, addressing the development of technologies in the analytical process and the importance of this dynamic biomass component in ecosystem processes related to carbon cycling and soil nutrients. We emphasize here the importance and need for new scientific research that seeks to develop methods of analysis, as well as to estimate the underground primary productivity, especially that of fine roots, so that the processes involved in the cycling of carbon and nutrients are better elucidated.
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Araújo, Isaac Jordão de Souza, Maurício Matté Zanini, Maurício Bottene Guarda, Bruna Marin Fronza, Simonides Consani, Isabela Pinheiro Cavalcanti Lima et Américo Bortolazzo Correr. « Diatomite filler for resin composites application – A new approach for materials improvement ». Research, Society and Development 11, no 16 (7 décembre 2022) : e268111637738. http://dx.doi.org/10.33448/rsd-v11i16.37738.
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The aim of this study was to evaluate physical-mechanical properties, degree of conversion, and chemical stability of a nanohybrid composite containing diatomite as filler. Degree of conversion (DC%) of diatomite-containing composite (Zirconfill®) was performed using FTIR immediately, and 1-, and 7-days post-curing. SEM was conducted to evaluate the surface of the resin after curing and measure particles size. Also, elemental characterization was performed to verify the major components of the composite through EDS. Mechanical characterization using 3-point bending test was performed prior and after thermo-cycling (10000 cycles) (n=10). Knoop microhardness (KHN) was used to characterize mechanical stability after chemical solutions aggression (water, juice, coffee, coke) up to 28 days (n=10/solution). After data normality evaluation using Shapiro-Wilk, One-way ANOVA and Tukey post hoc were conducted to verify differences between groups for DC% and mechanical properties. Split-plot ANOVA was used to compare groups for microhardness characterization (α=0.05). Immediate DC was 60% and significantly increased up to 80% at 7 days (p<0.05). Flexural strength of the diatomite-containing composite was 136.2 (23.7) MPa and significantly decreased to 75.1 (10.2) as a result of thermo-cycling. The flexural modulus was not significantly affected by the thermo-cycling (p>0.05). All the dietary solutions affected the KHN of the composite up to 21 days. For 28 days, the KHN evidenced and stabilization regarding all the solutions. Diatomite-containing composites present good degree of conversion and relevant mechanical properties and demonstrate time-dependent stability against chemical degradation.
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Mentzel, Stijn V., Bjoern Krenn, Dennis Dreiskaemper et Bernd Strauss. « The Impact of Wearing and Perceiving Colors on Hormonal, Physiological, and Psychological Parameters in Cycling ». Journal of Sport & ; Exercise Psychology 43, no 4 (1 août 2021) : 298–309. http://dx.doi.org/10.1123/jsep.2020-0150.
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This study examines the influence of wearing and perceiving colors in a cycling setting while also examining cortisol, heart rate, estimated maximum oxygen consumption, and subjective performance ratings. A total of 99 individuals completed the study, consisting of cortisol measurements, which compared baseline values to those after changing into a red or blue outfit, and a maximum cycling task performed wearing the same outfit while competing against a video opponent in red or blue. Each participant completed the protocol twice on separate days. Wearing a colored outfit showed no influence on cortisol levels. Regarding the cycling task, the participants wearing red had higher maximum heart rate values than when wearing blue. In addition, the results revealed increased maximum heart rate and maximum oxygen consumption values when perceiving an opponent in blue, especially when the participant also wore blue. No differences were found for the median heart rate or performance ratings.
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Siavoshian, S., HM Blottière, C. Cherbut, B. Kaeffer et JP Galmiche. « Effect of butyrate on the expression of cyclin-dependent kinases and cyclin D by HT-29 epithelial cells ». Reproduction Nutrition Development 37, no 3 (1997) : 341. http://dx.doi.org/10.1051/rnd:19970325.
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Kim, BR, SM Kang, E. de Josselin de Jong, HK Kwon et BI Kim. « In Vitro Red Fluorescence as an Indicator of Caries Lesion Activity ». Operative Dentistry 44, no 4 (1 juillet 2019) : 405–13. http://dx.doi.org/10.2341/17-369-l.
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SUMMARY This in vitro study examined the utility of comparing red fluorescence between active and inactive caries lesions and investigated whether changes in red fluorescence and fluorescence loss are influenced by lesion activity following remineralization. Sixty-two noncavitated smooth surface caries lesions on extracted human teeth were classified into active or inactive lesions using the Nyvad system prior to a 12-day pH-cycling procedure. Quantitative light-induced fluorescence-digital images were used to measure fluorescence parameters before and after pH cycling. At baseline, the intensity (ΔR) and area (AΔR) of red fluorescence were 1.5- and 2.2-fold higher in active lesions than in inactive lesions (p<0.05). The ratio of AΔR to lesion area was associated with classification of active lesions (odds ratio = 1.031; 95% confidence interval = 1.005–1.058). After pH cycling, the active lesions showed about 2- and 8-fold greater reductions in the median values of AΔR and fluorescence loss related to lesion volume (ΔQ) compared with inactive lesions (p<0.05). In conclusion, red fluorescence differs depending on lesion activity, and the red fluorescence area and lesion volume change following remineralization. The results suggest that measuring red fluorescence may be a useful way of objectively evaluating lesion activity of smooth surface lesions.
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Bernardo, J. M., et M. Ilhéu. « Red swamp crayfish (Procambarus clarkii) : Contribution to material cycling ». SIL Proceedings, 1922-2010 25, no 4 (octobre 1994) : 2447–49. http://dx.doi.org/10.1080/03680770.1992.11900666.
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Perakis, Steven S., Joselin J. Matkins et David E. Hibbs. « N2-Fixing Red Alder Indirectly Accelerates Ecosystem Nitrogen Cycling ». Ecosystems 15, no 7 (28 juillet 2012) : 1182–93. http://dx.doi.org/10.1007/s10021-012-9579-2.
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Telford, R. D., G. J. Sly, A. G. Hahn, R. B. Cunningham, C. Bryant et J. A. Smith. « Footstrike is the major cause of hemolysis during running ». Journal of Applied Physiology 94, no 1 (1 janvier 2003) : 38–42. http://dx.doi.org/10.1152/japplphysiol.00631.2001.
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There is a wide body of literature reporting red cell hemolysis as occurring after various forms of exercise. Whereas the trauma associated with footstrike is thought to be the major cause of hemolysis after running, its significance compared with hemolysis that results from other circulatory stresses on the red blood cell has not been thoroughly addressed. To investigate the significance of footstrike, we measured the degree of hemolysis after 1 h of running. To control for the potential effects of oxidative and circulatory stresses on the red blood cell, the same subjects cycled for 1 h at equivalent oxygen uptake. Our subjects were 10 male triathletes, who each completed two separate 1-h sessions of running and cycling at 75% peak oxygen uptake, which were performed in random order 1 wk apart. Plasma free hemoglobin and serum haptoglobin concentrations were measured as indicators of hemolysis. We also measured methemoglobin as a percentage of total hemoglobin immediately postexercise as an indicator of red cell oxidative stress. Plasma free hemoglobin increased after both running ( P < 0.01) and cycling ( P < 0.01), but the increase was fourfold greater after running ( P < 0.01). This was reflected by a significant fall in haptoglobin 1 h after the running trials, whereas no significant changes occurred after cycling at any sample point. Methemoglobin increased twofold after both running and cycling ( P < 0.01), with no significant differences between modes of exercise. The present data indicate that, whereas general circulatory trauma to the red blood cells associated with 1 h of exercise at 75% maximal oxygen uptake may result in some exercise-induced hemolysis, footstrike is the major contributor to hemolysis during running.
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Jörg, David J., Doris H. Fuertinger et Peter Kotanko. « Mechanisms of hemoglobin cycling in anemia patients treated with erythropoiesis-stimulating agents ». PLOS Computational Biology 19, no 1 (24 janvier 2023) : e1010850. http://dx.doi.org/10.1371/journal.pcbi.1010850.
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Patients with renal anemia are frequently treated with erythropoiesis-stimulating agents (ESAs), which are dynamically dosed in order to stabilize blood hemoglobin levels within a specified target range. During typical ESA treatments, a fraction of patients experience hemoglobin ‘cycling’ periods during which hemoglobin levels periodically over- and undershoot the target range. Here we report a specific mechanism of hemoglobin cycling, whereby cycles emerge from the patient’s delayed physiological response to ESAs and concurrent ESA dose adjustments. We introduce a minimal theoretical model that can explain dynamic hallmarks of observed hemoglobin cycling events in clinical time series and elucidates how physiological factors (such as red blood cell lifespan and ESA responsiveness) and treatment-related factors (such as dosing schemes) affect cycling. These results show that in general, hemoglobin cycling cannot be attributed to patient physiology or ESA treatment alone but emerges through an interplay of both, with consequences for the design of ESA treatment strategies.
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Oyebamiji, A. K., E. T. Akintayo, C. O. Akintayo, H. O. Aworinde, O. D. Adekunle et S. A. Akintelu. « Cyclic RGD-containing peptides : in silico exploration against BCL-X(L) ». Ukrainian Biochemical Journal 95, no 2 (14 juin 2023) : 93–105. http://dx.doi.org/10.15407/ubj95.02.093.
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Сyclic peptides attract attention for possible applications in cancer treatment. We examined the ability of six cyclic RGD-containing peptides-based compounds to inhibit B-cell lymphoma-extra-large (Bcl-XL) (PDB ID: 3zk6) using the in silico method. We observed that the addition of electron withdrawing group (–Cl) to cyclic RGD-containing peptides-based compound induced a radical improvement in the hydrogen bond strength with Arg139 in Bcl-XL. Compound F with -9.2 kcal/mol was observed to be positioned at the best-docked site in the binding pocket of Bcl-XL and therefore suggested to have greater potential anticancer ability than other studied compounds as well as the referenced compound (Doxorubicin). The ADMET properties of compound F and Doxorubicin were investigated and reported. Our findings may open door for the design and development of library of efficient cyclic RGD-containing peptides-based drug-like compounds as potential anti- cancer agents. Keywords: Bcl-X(L), carcinogesis, cyclic RGD peptides, in silico study, modeling, peptide-protein interaction
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Vos, Hendrik. « Ruth Oldenziel et al. (red.) Cycling Cities : the European Experience. » Tijdschrift voor Sociale en Economische Geschiedenis/ The Low Countries Journal of Social and Economic History 15, no 4 (10 mars 2019) : 147. http://dx.doi.org/10.18352/tseg.1055.
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Forbes, Scott C., Darren G. Candow, Jonathan P. Little, Charlene Magnus et Philip D. Chilibeck. « Effect of Red Bull Energy Drink on Repeated Wingate Cycle Performance and Bench-Press Muscle Endurance ». International Journal of Sport Nutrition and Exercise Metabolism 17, no 5 (octobre 2007) : 433–44. http://dx.doi.org/10.1123/ijsnem.17.5.433.
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The purpose of this study was to determine the effects of Red Bull energy drink on Wingate cycle performance and muscle endurance. Healthy young adults (N = 15, 11 men, 4 women, 21 ± 5 y old) participated in a crossover study in which they were randomized to supplement with Red Bull (2 mg/kg body mass of caffeine) or isoenergetic, isovolumetric, noncaffeinated placebo, separated by 7 d. Muscle endurance (bench press) was assessed by the maximum number of repetitions over 3 sets (separated by 1-min rest intervals) at an intensity corresponding to 70% of baseline 1-repetition maximum. Three 30-s Wingate cycling tests (load = 0.075 kp/kg body mass), with 2 min recovery between tests, were used to assess peak and average power output. Red Bull energy drink significantly increased total bench-press repetitions over 3 sets (Red Bull = 34 ± 9 vs. placebo = 32 ± 8, P < 0.05) but had no effect on Wingate peak or average power (Red Bull = 701 ± 124 W vs. placebo = 700 ± 132 W, Red Bull = 479 ± 74 W vs. placebo = 471 ± 74 W, respectively). Red Bull energy drink significantly increased upper body muscle endurance but had no effect on anaerobic peak or average power during repeated Wingate cycling tests in young healthy adults.
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Telford, R. D., G. J. Sly et J. A. Smith. « RED CELL HEMOLYSIS DURING RUNNING AND CYCLING AT EQUIVALENT METABOLIC COST459 ». Medicine & Science in Sports & Exercise 29, Supplement (mai 1997) : 80. http://dx.doi.org/10.1097/00005768-199705001-00458.
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Johnson, Dale W., Helga Van Miegroet, Steven E. Lindberg, Donald E. Todd et Robert B. Harrison. « Nutrient cycling in red spruce forests of the Great Smoky Mountains ». Canadian Journal of Forest Research 21, no 6 (1 juin 1991) : 769–87. http://dx.doi.org/10.1139/x91-110.
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Nutrient distributions, concentrations, and fluxes in two red spruce (Picearubens Sarg.) stands in the Great Smoky Mountains are described and used to evaluate various hypotheses for recent decline of this species. These forests, like others in the southern Appalachians, were relatively rich in N and low in base cation status. The combination of high atmospheric N and S deposition, little or no N or S retention, relatively high N mineralization, and extremely acid soils caused soil solutions to be dominated by NO3−, SO42−, Al, and H+. Soil solution Al in these sites (most of which was in monomeric form) occasionally reached levels noted to inhibit base cation uptake and root growth in solution culture studies. These pulses of Al were driven by pulses of NO3− and, to a lesser extent, SO42− in soil solution. However, fine roots were present at depths of up to 60 cm in the mineral soil, indicating that Al concentrations had not become consistently toxic to roots. Solution fluxes (both throughfall and soil leaching) exceeded litter-fall fluxes for all the macronutrients at both sites, a typical situation for K and S, but most unusual for N, P, Ca, and Mg. There are significant implications of these fluxes and of the apparent net uptake of N by foliage in terms of how vegetation uptake and translocation are calculated. Some new formulations are suggested, but measurement errors in systems with such a predominance of hydrologic fluxes make foliar leaching and, therefore, uptake and translocation calculations extremely uncertain. Although there are no outward signs of decline in these forests (other than balsam fir (Abiesbalsamea (L.) Mill.) mortality due to the balsam woolly adelgid (Adelgespiceae (Ratz.))), the high rates of NO3− leaching rates and the borderline soil solution Al values suggest that these systems are under stress. Whether these factors actually lead to a dieback or growth decline remains to be seen.
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Perakis, Steven S., Joselin J. Matkins, David E. Hibbs et Manuela Huso. « Erratum to : N2-Fixing Red Alder Indirectly Accelerates Ecosystem Nitrogen Cycling ». Ecosystems 17, no 4 (31 janvier 2014) : 750. http://dx.doi.org/10.1007/s10021-014-9746-8.
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Liu, Yubin, Tongbin Lan, Weifeng Zhang, Xiaokun Ding et Mingdeng Wei. « Hierarchically porous anatase TiO2microspheres composed of tiny octahedra with enhanced electrochemical properties in lithium-ion batteries ». J. Mater. Chem. A 2, no 47 (2014) : 20133–38. http://dx.doi.org/10.1039/c4ta04227a.
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Hierarchical porous anatase TiO2microspheres composed of ultrathin rod-like structures in the radial direction were fabricatedviaa growth model of oriented attachment. They exhibited high rate performance and excellent cycling stability.
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Oliveira, Mauro Wagner de, José Douglas Bezerra da Silva, Terezinha Bezerra Albino Oliveira, Dalmo de Freitas Santos, Túlio Menezes Tenório, Esly da Costa Soares et Grazielly Lessa Rocha. « Dry matter accumulation and nutrient cycling by soil cover plants in an intensive corn silage production system ». Research, Society and Development 11, no 8 (26 juin 2022) : e45611831008. http://dx.doi.org/10.33448/rsd-v11i8.31008.
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This study aimed to evaluate dry matter accumulation and nutrient cycling by soil cover plants in an intensive corn silage production system. At the beginning of October, a study consisting of five soil cover plants, plus a control treatment (fallow area vegetation) was installed. The following cover plants were used: brachiaria brizantha, brachiaria ruziziensis, crotalaria juncea, jack bean and velvet bean. At the beginning of February of the year following sowing, we evaluated dry matter and nutrient accumulation in plant shoots. There was a significant effect at 0.1% of the cover plants on dry matter and nutrient accumulation. The average values for dry matter accumulation in plant shoots were 19.88; 18.06; 16.38; 9.66; 8.96 and 4.26 t ha-1 for brachiaria brizantha, crotalaria juncea, brachiaria ruziziensis, jack bean, velvet bean and fallow area vegetation, respectively. The highest nitrogen accumulation was observed in crotalaria juncea (343 kg ha-1), followed by jack bean (269 kg ha-1). For brachiaria brizantha and ruziziensis, N accumulation of 247 and 216 kg ha-1 were found, respectively. Brachiaria brizantha had the highest accumulation of phosphorus and potassium, with average values of 39 and 362 kg ha-1. In the fallow area vegetation, the accumulations of N, P and K were 42; 9.0 and 62 kg ha-1, respectively.
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Lucas, Shelley. « The Red Zinger/Coors Classic Bicycle Race : Commemorations and Re-Cycled Narratives ». Sport History Review 50, no 2 (1 novembre 2019) : 173–86. http://dx.doi.org/10.1123/shr.2019-0033.
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The Red Zinger Bicycle Classic, later renamed the Coors International Bicycle Classic, is renowned for its influence on the development of men’s and women’s cycle racing in the United States. Recent efforts to create a United States Cycling Monument in Boulder, Colorado, centered on commemorating what is commonly referred to as the Coors Classic. I use the proposed monument as a starting point for exploring how the Coors Classic is being remembered, particularly with respect to the women’s competition. Where do women cyclists and their contests fit into the commemoration of this race? My analysis illuminates gendered aspects of this race and what I refer to as re-cycled narratives. I conclude with a concern about the impact of re-cycled narratives on present-day women’s cycling and consider historian Beverly Southgate’s call for thinking about histories for the future.
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Amenda, Lars. « „Major Taylor, der schwarze Star!“ Radrennsport in Deutschland um 1900 zwischen Fairness und Rassismus ». STADION 46, no 2 (2022) : 195–223. http://dx.doi.org/10.5771/0172-4029-2022-2-195.
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Marshall Walter „Major“ Taylor (1878–1932) was a massively popular Black US American cyclist around 1900. In late 19th century United States he encountered severe racism in cycling and beyound despite (or because) his obvious sportive talent. In 1899 he won the world championship in sprinting the mile and became a professional track cyclist. In Europe, in France in particular, the cycling world impatiently looked forward for him particpating in races. In 1901 he finally travelled abroad for his first European tour. The paper examines Major Taylor’s appearances in Germany, focusing on the years 1901 to 1903. His first ever start in Europe took place in Berlin-Friedenau on April 8, 1901. Major Taylor was regarded as a huge sensation in the highly popular track cycling around the turn of the 20th century. The influential German cycling newspaper Rad-Welt promoted him and welcomed him personally in their Berlin office after his first races. German rivals such as Willy Arend from Hannover faced the Black US American cyclist with highest respect. Nevertheless, a few riders and parts of the audience showed some racist behavior, including blackfacing before his first ever start. However, the Rad-Welt strongly condemmed unfair tactics against Major Taylor and generally called for fairness. Major Taylor successfully participated in a number of track races in German cities such as Berlin, Hannover, Cologne and others from 1901 to 1903 and remained a sport celebrity in Germany for many years. In the course of the 20th century his fame then waned both in the US and Germany.
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Hidalgo, Daniel, Jacob Bejder, Ramona Pop, Kyle Gellatly, Yung Hwang, S. Maxwell Scalf, Anna Eastman et al. « Epor Stimulates Rapid Cycling and Larger Red Cells during Mouse and Human Erythropoiesis ». Blood 138, Supplement 1 (5 novembre 2021) : 852. http://dx.doi.org/10.1182/blood-2021-154403.
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Abstract Erythroid terminal differentiation (ETD) entails cell divisions coupled to decreasing cell size. The tight link between the number of cell divisions and red cell size is apparent in nutritional deficiencies or genetic variants in which fewer cycles result in larger red cells. Here we investigated novel EpoR functions, finding that EpoR signaling disrupts the relationship between cell cycle number and cell size, simultaneously promoting rapid cycling and the formation of larger red cells. EpoR is essential for erythroblast survival, but it is unclear whether it has other non-redundant functions. To address this, we developed a genetic system in which we rescue mouse Epor -/- fetal liver progenitors from apoptosis by transduction with the anti-apoptotic protein Bcl-x L, and compare their ensuing differentiation with that of Epor -/- progenitors rescued with EpoR (Fig 1a). We found that the Bcl-x L survival signal, in the absence EpoR, supported formation of enucleated red cells. However, key ETD features were abnormal. First, Bcl-x L-transduced Epor -/- erythroblasts underwent slower and fewer cell cycles (Figure 1b), differentiating prematurely into enucleated red cells. Premature induction of the cyclin-dependent-kinase inhibitor p27 KIP1 was in part responsible for the fewer cycles in the absence of EpoR signaling. We confirmed that EpoR also stimulates rapid cycling in wild-type erythroblasts in vivo, using a mouse transgenic for a live-cell reporter of cell cycle speed. Second, using imaging flow cytometry, we found that Bcl-x L-transduced Epor -/- erythroblasts were smaller than EpoR-transduced Epor -/- cells (Fig 1c,d). By doubly transducing Epor -/- erythroblasts with both Bcl-x L and EpoR, we verified that EpoR absence, and not Bcl-x L overexpression, is responsible for the smaller size of Bcl-x L-transduced Epor -/- erythroblasts and reticulocytes. Bcl-x L-transduced Epor -/- erythroblasts failed to upregulate the transferrin receptor, suggesting that iron deficiency may be responsible for their smaller size. However, neither iron supplementation, nor transduction with the transferrin receptor, rescued their smaller size. Iron regulates cell size through Heme-regulated eIF2α kinase (HRI). To definitively test the role of iron and HRI, we generated mice doubly deleted for both EpoR and HRI. We then rescued both Epor -/- and Epor -/-Hri -/- -fetal liver cells in parallel, by transduction with either Bcl-x L or EpoR. In agreement with the known role of HRI as a negative regulator of erythroblast size, both Bcl-x L- transduced and EpoR-transduced erythroblasts were larger on the Epor -/-Hri -/- genetic background. However, the difference in size between Bcl-x L and EpoR-rescued erythroblasts persisted in Epor -/-Hri -/- erythroblasts and reticulocytes (Fig 1c,d), conclusively showing that EpoR signaling regulates cell size independently of the HRI pathway. EpoR promoted increased erythroblast and reticulocyte cell size in wild-type mice in vitro and in vivo, in response to Epo concentrations ranging from 10 to 10,000 mU/ml. We also evaluated the effect of Epo on red cell size in humans, in two independent studies, where healthy volunteers were administered Epo for either 3 weeks (20 IU /kg every 48 hours, 25 subjects, Study #1) or for 7 weeks (weekly Epo dosing that increased hemoglobin by 10 -15%; 24 subjects, Study #2). In a third intervention, 21 subjects participated in a randomized double-blind placebo-controlled crossover study in which 900 ml of whole blood was withdrawn from the treatment group by venipuncture. In all three studies, the increase in MCV in the treatment groups persisted long after Epo and reticulocyte levels returned to baseline (Figure 2). There was no correlation between MCV and the reticulocyte count, whose time courses were clearly divergent (r < 0.1, Pearson's product-moment correlation). Further, computational simulation suggests that the extent and duration of the increase in MCV is unlikely to be the result of skewing of the circulating red cell population in favor of younger, larger red cells. Our work reveals a paradoxical EpoR-driven increase in erythroblast cycling simultaneously with increased erythroblast and red cell size. It suggests that EpoR alters the relationship between cell cycle and biomass in erythroblasts. It further suggests that hypoxia, anemia and other high-Epo syndromes are new diagnostic interpretations of increased MCV in the clinic. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.
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Li, Huani, Yuhao Zhang, Beihong Liu, Zhihui Gao, Genfu Zhao, Tingting Liu, Xiang Gao, Shubiao Xia et Hong Guo. « Red phosphorus confined in hierarchical hollow surface-modified Co9S8 for enhanced sodium storage ». Sustainable Energy & ; Fuels 4, no 5 (2020) : 2208–19. http://dx.doi.org/10.1039/d0se00251h.
Texte intégralRésumé :
The encapsulation-type structured P@Co9S8 materials assembled with surface-modified hierarchical hollow spherical Co9S8 exhibit ultralong cycling and high rate performance for SIBs.
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Dong, Qi, Xiang Sun, Nengzhong Lei et Bin Liu. « Effect of Dry–Wet Cycling on the Degradation Characteristics and Mechanisms of Red Sandstone ». Geofluids 2023 (1 avril 2023) : 1–15. http://dx.doi.org/10.1155/2023/9950331.
Texte intégralRésumé :
The physical and mechanical parameters and degradation mechanisms of red sandstone in the Mount Wuyi scenic area were studied under the action of dry–wet cycles. Dry–wet cycle, acoustic wave velocity, water saturation rate, and triaxial compression tests were conducted, aided by scanning electron microscopy and X-ray diffraction testing techniques. The study’s results show that the dry–wet cycle effect on red sandstone is a major factor in the degradation of its physical and mechanical parameters and that its microstructural characteristics are significantly affected. The P-wave velocity, peak strength, elastic modulus, internal friction angle, and cohesion decreased, the water content and peak strain increased, and the elastic modulus was the most sensitive to dry–wet cycles. A dry–wet cycle’s action severely damages the microstructural integrity of the red sandstone. After 15 dry–wet cycles, the interstitial fillings between the skeletal grains are dissolved over a large area, microfractures are interwoven throughout, and the structure is severely fragmented. The microstructural degradation of the red sandstone by dry–wet cycles mainly manifests in the dissolution of the interstitial filler, and the relative content of calcite as an interstitial filler is reduced by 46.6% after 15 dry–wet cycles. The proposed strength decay prediction equation has reference significance for the strength prediction of the red sand conglomerate in the project. This study’s results can provide theoretical support for the landscape protection of rock masses and the prevention of engineering geological hazards.
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Wu, Na, Hu-Rong Yao, Ya-Xia Yin et Yu-Guo Guo. « Improving the electrochemical properties of the red P anode in Na-ion batteries via the space confinement of carbon nanopores ». Journal of Materials Chemistry A 3, no 48 (2015) : 24221–25. http://dx.doi.org/10.1039/c5ta08367b.
Texte intégralRésumé :
By encapsulating red P into a special hierarchical porous carbon (HPC) substrate with 2 nm pores, the P@HPC composite no longer involves huge pulverization during sodiation/desodiation but is provided with improved cycling stability (the capacity retention > 88% after 200 cycles).
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Li, Wei-Jie, Shu-Lei Chou, Jia-Zhao Wang, Hua-Kun Liu et Shi-Xue Dou. « Significant enhancement of the cycling performance and rate capability of the P/C composite via chemical bonding (P–C) ». Journal of Materials Chemistry A 4, no 2 (2016) : 505–11. http://dx.doi.org/10.1039/c5ta08590j.
Texte intégralRésumé :
The red phosphorus and graphene nanoplate composite delivered a high reversible capacity of 1146 mA h g−1 at a current density of 100 mA g−1 and an excellent cycling stability of 200 cycles with 92.5% capacity retention.
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Chen, Xiangmei, Yongqiang Ren, Baoli Tang, Guojin Li, Feitian Zhang et Yunfei Liu. « Experimental Study of Macro- and Micro-Scopic Damage in Red Sandstone under Dry and Wet Cycling ». Advances in Civil Engineering 2024 (23 avril 2024) : 1–9. http://dx.doi.org/10.1155/2024/6681592.
Texte intégralRésumé :
The high-strength red sandstone in its natural state is subjected to significant strength deterioration under alternating wet and dry conditions, which can cause many catastrophic problems in the process of engineering construction. It is important to deeply understand the damage mechanism of red sandstone under the action of dry and wet cycles. Therefore, this paper explores the mechanism of red sandstone’s uniaxial deformation and failure through indoor uniaxial compression tests, studies the damage to the microstructure of red sandstone under wet–dry cycles using scanning electron microscopy, and establishes a damage variable based on fractal dimension. The results show that with the increase of wet–dry cycles, the peak stress of red sandstone shows a decreasing trend, and the minimum peak stress is 17.3 MPa, which is a 46.62% decrease compared to the sample with 0 wet–dry cycles. During the wet–dry cycle process, there are four deformation characteristics of red sandstone samples, namely, crack compression, crack extension, progressive fracture, and crack penetration. SEM images show that the porosity, pore area, and fractal dimension all show a nonlinear increase, and the maximum damage variable can reach 10.41%. The research results can provide guidance for engineering design and slope failure mechanism research in red sandstone areas.
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Nemkov, Travis, Sarah C. Skinner, Elie Nader, Davide Stefanoni, Mélanie Robert, Francesca Cendali, Emeric Stauffer et al. « Acute Cycling Exercise Induces Changes in Red Blood Cell Deformability and Membrane Lipid Remodeling ». International Journal of Molecular Sciences 22, no 2 (18 janvier 2021) : 896. http://dx.doi.org/10.3390/ijms22020896.
Texte intégralRésumé :
Here we describe the effects of a controlled, 30 min, high-intensity cycling test on blood rheology and the metabolic profiles of red blood cells (RBCs) and plasma from well-trained males. RBCs demonstrated decreased deformability and trended toward increased generation of microparticles after the test. Meanwhile, metabolomics and lipidomics highlighted oxidative stress and activation of membrane lipid remodeling mechanisms in order to cope with altered properties of circulation resulting from physical exertion during the cycling test. Of note, intermediates from coenzyme A (CoA) synthesis for conjugation to fatty acyl chains, in parallel with reversible conversion of carnitine and acylcarnitines, emerged as metabolites that significantly correlate with RBC deformability and the generation of microparticles during exercise. Taken together, we propose that RBC membrane remodeling and repair plays an active role in the physiologic response to exercise by altering RBC properties.
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Quideau, S. A., et J. G. Bockheim. « Biogeochemical Cycling following Planting to Red Pine on a Sandy Prairie Soil ». Journal of Environmental Quality 26, no 4 (juillet 1997) : 1167–75. http://dx.doi.org/10.2134/jeq1997.00472425002600040032x.
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Chase, Zanna, Adina Paytan, Kenneth S. Johnson, Joseph Street et Ying Chen. « Input and cycling of iron in the Gulf of Aqaba, Red Sea ». Global Biogeochemical Cycles 20, no 3 (septembre 2006) : n/a. http://dx.doi.org/10.1029/2005gb002646.
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Dieckmann, Ulf, Paul Marrow et Richard Law. « Evolutionary cycling in predator-prey interactions : population dynamics and the red queen ». Journal of Theoretical Biology 176, no 1 (septembre 1995) : 91–102. http://dx.doi.org/10.1006/jtbi.1995.0179.
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El-Khaled, YC, F. Roth, A. Tilstra, N. Rädecker, DB Karcher, B. Kürten, BH Jones, CR Voolstra et C. Wild. « In situ eutrophication stimulates dinitrogen fixation, denitrification, and productivity in Red Sea coral reefs ». Marine Ecology Progress Series 645 (9 juillet 2020) : 55–66. http://dx.doi.org/10.3354/meps13352.
Texte intégralRésumé :
Eutrophication (i.e. the increase of [in-]organic nutrients) may affect the functioning of coral reefs, but knowledge about the effects on nitrogen (N) cycling and its relationship to productivity within benthic reef communities is scarce. Thus, we investigated how in situ manipulated eutrophication impacted productivity along with 2 counteracting N-cycling pathways (dinitrogen [N2]-fixation, denitrification), using a combined acetylene assay. We hypothesised that N2-fixation would decrease and denitrification increase in response to eutrophication. N fluxes and productivity (measured as dark and light oxygen fluxes assessed in incubation experiments) were determined for 3 dominant coral reef functional groups (reef sediments, turf algae, and the scleractinian coral Pocillopora verrucosa) after 8 wk of in situ nutrient enrichment in the central Red Sea. Using slow-release fertiliser, we increased the dissolved inorganic N concentration by up to 7-fold compared to ambient concentrations. Experimental nutrient enrichment stimulated both N2-fixation and denitrification across all functional groups 2- to 7-fold and 2- to 4-fold, respectively. Productivity doubled in reef sediments and remained stable for turf algae and P. verrucosa. Our data therefore suggest that (1) turf algae are major N2-fixers in coral reefs, while denitrification is widespread among all investigated groups; (2) surprisingly, and contrary to our hypothesis, both N2-fixation and denitrification are involved in the response to moderate N eutrophication, and (3) stimulated N2-fixation and denitrification are not directly influenced by productivity. Our findings underline the importance and ubiquity of microbial N cycling in (Red Sea) coral reefs along with its sensitivity to eutrophication.
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Ma, Yang, Zhou, Feng et Yuan. « Risk Riding Behaviors of Urban E-Bikes : A Literature Review ». International Journal of Environmental Research and Public Health 16, no 13 (28 juin 2019) : 2308. http://dx.doi.org/10.3390/ijerph16132308.
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In order to clearly understand the risky riding behaviors of electric bicycles (e-bikes) and analyze the riding characteristics, we review the research results of the e-bike risky riding behavior from three aspects: the characteristics and causes of e-bike accidents, the characteristics of users’ traffic behavior, and the prevention and intervention of traffic accidents. The analysis results show that the existing research methods on risky riding behavior of e-bikes mainly involve questionnaire survey methods, structural equation models, and binary probability models. The illegal occupation of motor vehicle lanes, over-speed cycling, red-light running, and illegal manned and reverse cycling are the main risky riding behaviors seen with e-bikes. Due to the difference in physiological and psychological characteristics such as gender, age, audiovisual ability, responsiveness, patience when waiting for a red light, congregation, etc., there are differences in risky cycling behaviors of different users. Accident prevention measures, such as uniform registration of licenses, the implementation of quasi-drive systems, improvements of the riding environment, enhancements of safety awareness and training, are considered effective measures for preventing e-bike accidents and protecting the traffic safety of users. Finally, in view of the shortcomings of the current research, the authors point out three research directions that can be further explored in the future. The strong association rules between risky riding behavior and traffic accidents should be explored using big data analysis. The relationships between risk awareness, risky cycling, and traffic accidents should be studied using the scales of risk perception, risk attitude, and risk tolerance. In a variety of complex mixed scenes, the risk degree, coupling characteristics, interventions, and the coupling effects of various combination intervention measures of e-bike riding behaviors should be researched using coupling theory in the future.
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Baran, V., J. Veselá, P. Rehák et J. Koppel. « Immunocytochemical localization of cyclin/proliferating cell nuclear antigen (PCNA) in fertilized eggs of mice ». Reproduction Nutrition Development 32, no 3 (1992) : 241–48. http://dx.doi.org/10.1051/rnd:19920303.
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Razanamahefa, L., C. Costa et S. Bardon. « Retinoic acid inhibits insulin-induced cyclin Dl gene expression in T47D breast cancer cells ». Reproduction Nutrition Development 37, no 3 (1997) : 374–75. http://dx.doi.org/10.1051/rnd:19970381.
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Käärik, Maike, Mati Arulepp et Jaan Leis. « Partial Oxidation to Extend the Lifetime of Nanoporous Carbon in an Ultracapacitor with Li2SO4 Electrolyte ». Molecules 28, no 7 (25 mars 2023) : 2944. http://dx.doi.org/10.3390/molecules28072944.
Texte intégralRésumé :
A TiC-derived carbon (CDC) and its partially oxidized derivative (ox-red-CDC), oxidized by a modified Hummers method, were studied as promising electrode materials for electrochemical energy storage. To evaluate the electrochemical properties of the carbon materials, cyclic voltammetry, galvanostatic cycling, and electrochemical impedance spectroscopy measurements were performed in 1 M Li2SO4 using 2- and 3-electrode cells. A partially oxidized surface was shown to improve the capacitance and electrochemical stability of a nanoporous CDC at positive potential values. The respective anodic capacitance of 80 F cm−3 reveals a 15% improvement over the non-oxidized CDC. At negative potential values, the capacitance of two carbon materials is almost equal, 97 vs. 93 F cm−3, for the non-oxidized and partially oxidized CDC materials, respectively. An asymmetric 2-electrode ultracapacitor containing ox-red-CDC as the anode and pristine CDC as the cathode demonstrated an excellent cycle life. The temporary repolarization of the 2-electrode cell after thousands of charge–discharge cycles increased the capacitance and improved the cycling characteristics, likely due to regeneration and cleaning of the electrode surface.
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O'Brien, Peter James, Hua Shen, Janice E. Weiler, S. Mehdi Mirsalimi et Richard J. Julian. « Myocardial calcium cycling defect in furazolidone cardiomyopathy ». Canadian Journal of Physiology and Pharmacology 69, no 12 (1 décembre 1991) : 1833–40. http://dx.doi.org/10.1139/y91-271.
Texte intégralRésumé :
We have previously demonstrated that in furazolidone-induced congestive heart failure in turkeys the specific Ca2+-ATPase activity of myocardial sarcoplasmic reticulum (SR) is 60% increased in compensation for a 50% depression in net Ca2+-sequestration activity. This study tested the hypothesis that SR Ca2+-uptake and Ca2+-ATPase activities were uncoupled in this cardiomyopathy because of increased Ca2+-release channel activity. A novel microassay was used to monitor Ca2+ transport by myocardial homogenates using the fluorescent Ca2+ dye indo 1 to indicate extravesicular ionized Ca2+. The method is applied to cyropreserved biopsy specimens of myocardium and requires only 50 mg tissue. Both SR Ca2+-pump and SR Ca2+-channel activity were estimated using the channel-inhibitor ruthenium red (RR) and the mitochondrial inhibitor sodium azide. The specificity of the RR inhibition was confirmed using ryanodine. Cardiomyopathy was induced in 2-week-old turkey pouits by the addition of 0.07% furazolidone to their feed for 4 weeks. Compared with controls, myocardial maximal Ca2+-channel activity relative to maximal Ca2+-pump activity was 22% greater and duration of Ca2+-channel activity was 100% increased. However, the heart failure birds had 43 and 53% decreases in absolute maximal Ca2+-pumping and Ca2+-channel activities, respectively. The abnormal Ca2+-channel activity resulted in 200% greater time before initiation of net Ca2+ sequestration and 700% greater final myocardial Ca2+ concentrations. For all birds, the Ca2+-accumulating activity was highly correlated with Ca2+-release activity (all p < 0.05). These data indicate that in this animal model of congestive heart failure there is defective SR Ca2+-channel function resulting in abnormal Ca2+ homeostasis. However, this defect can only partially explain our previous finding of furazolidone-induced uncoupling of Ca2+ uptake from Ca2+-ATPase activities. The consequent myocardial Ca2+ overload predisposes the heart to fatigue and irreversible failure.Key words: sarcoplasmic reticulum, calcium sequestration, furazolidone cardiomyopathy, indo 1 spectrofluorometry.
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Modepalli, Susree, Anna Eastman, Chloe Shaw, Shangqin Guo, Shilpa M. Hattangadi et Gary M. Kupfer. « Novel Fluorescent Timer Tool Enables Characterization of Erythropoietic Differentiation Based on Differential Cell Cycling Speeds ». Blood 136, Supplement 1 (5 novembre 2020) : 27–28. http://dx.doi.org/10.1182/blood-2020-141666.
Texte intégralRésumé :
Erythropoietic proliferation and differentiation are coordinated and regulated by a complex compendium of molecular components and networks. Understanding the underlying mechanisms and the dependence of erythroid maturation on cell-cycle behavior can provide a detailed insight into normal and ineffective erythropoiesis. The dynamic cell cycle speed of erythroid progenitors reflects the erythron's response to external stimuli, such as severe anemia or bleeding. Aberrant cell cycle speed also defines pathologic conditions, such as the inability to compensate for anemia in diseases of ineffective erythropoiesis like hemolysis or thalassemia. Current methods to resolve cell cycle length heterogeneity at a single-cell level in real-time present with limitations, including cellular toxicity, insufficient intensity, and dilution over subsequent cell divisions. We utilized a unique live-cell reporter of cell cycle speed using a histone H2B-FT fusion protein containing the color-changing Fluorescent Timer (FT) protein. The FT protein emits blue fluorescence when newly synthesized and matures into a stable red fluorescent protein over 1.2 hours. The fusion protein thus distinguishes faster cycling cells from slower-cycling ones based on the intracellular ratio between blue and red fluorescence. Knock-in mice expressing H2B-FT from a universally active locus under the control of a dox inducible promoter were previously generated and characterized. We successfully characterized the stress erythropoietic response of the spleen and bone marrow (BM) after inducing hemolytic anemia by phenylhydrazine (PHZ) administration in these transgenic mice. Flow cytometric investigation of successive stages of erythroblasts revealed that all stages of erythroblasts maintain rapid cell division after the hemolytic insult (****p<0.0001, Mann-Whitney test) and not only early progenitors, as previously thought. We also observed that stress erythropoiesis in the spleen is stimulated almost immediately after hemolysis. Most importantly, we observed that the last nucleated cell stage, orthochromatic erythroblasts, stop dividing much earlier than normal, allowing them to terminally differentiate into reticulocytes much faster to alleviate the anemia. Blue-red (BR) profiles of the different erythroblasts from the PHZ-treated animals showed a marked distribution into fast-cycling (high blue fluorescence) and slow-cycling (high red fluorescence) subpopulations. Histograms of normalized BR ratios revealed significantly differentially cycling subpopulations in the polychromatic erythroblasts from spleen and orthochromatic erythroblasts from BM under stress. Mass spectrometric analysis of the differentially cycling subpopulations sorted from the respective erythroblasts shows upregulation of genes encoding cell cycle related and phospho-proteins. We are currently performing comparative analyses with openly available proteomic data. With the Erythropoietin (Epo) model for inducing stress erythropoiesis, we do find a modest increase in blue-red ratios for each of the erythroblast populations in Epo-treated timer mice as compared to the PHZ model. A recent study on steroid resistance in DBA reported that dexamethasone (dex) treatment of peripheral blood progenitors caused the specific upregulation of p57Kip2 leading to higher expansion and accelerated erythroid differentiation. We will utilize in vitro human CD34+ primary cell culture to assess the erythropoietic response to known treatments of anemia of chronic kidney disease and Diamond-Blackfan Anemia, like Epo and dex, respectively. These findings shed new light on the normal response to external stress, underscoring the possibility of precise quantification of cell cycle speed in animal models of anemia. We highlight the use of a sophisticated fluorescent system that can help elucidate the role of cell cycle speed in stress hematopoiesis, and determine the mechanistic pathways acting at single-cell or population level. Further phosphoproteomic investigation can lead to identification of discrete molecular targets regulating erythroid cell proliferation and differentiation with potential therapeutic implications. The tool can aid in answering important questions delineating cell cycle dynamics as the cause or consequence of erythroid differentiation in normal and pathophysiological conditions. Disclosures No relevant conflicts of interest to declare.
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Economou-Eliopoulos, Maria, Marioka Kontou et Ifigeneia Megremi. « Biogeochemical Redox Processes Controlling the Element Cycling : Insights from Karst-Type Bauxite, Greece ». Minerals 12, no 4 (5 avril 2022) : 446. http://dx.doi.org/10.3390/min12040446.
Texte intégralRésumé :
The occurrence of very-high-grade bauxite ores of karst-type deposits resulting from Fe-leaching is of particular importance, because they are widespread in the Mediterranean metallogenetic province and result in the natural beneficiation of the ore quality. The present study focuses on mineral transformations and variations of major and trace elements, including platinum-group elements (PGE) and mineral chemistry along a bauxite profile from the Parnassos-Ghiona deposit, Greece underlying a fault. The most salient feature of the multicolor ores (grey–whitish, yellowish, deep red, deep grey to brown-red color, from top to bottom) is their association with fossilized and present-day microorganisms, which, by their reducing and/or oxidizing activity, catalyze redox reactions and provide nucleation sites for the precipitation of secondary minerals. Texture relationships between mineral and variations in the mineral chemistry, suggesting the sequence in their formation, indicate a multistage evolution. The recorded compositional variations show that the Al enrichment is accompanied by increase in the TOC, As, Pd and U, and chondrite-normalized REE patterns exhibit a similar trend and positive Ce anomalies. A lower (Pt + Pd) content and higher Pd/Pt ratio, ranging from 1.0 to 5.5 in the bauxite profile compared to those in Fe-Ni laterite deposits with the Pd/Pt ratio ranging from 0.1 to 0.68, reflect the higher solubility and mobility of Pd compared to that of Pt, and differences in their origin and genesis. A positive correlation between Pd and As and the elevated As content (up to 960 mg/kg) in multicolor ores compared to brown-red samples (average 10 mg/kg As) confirms their mobilization and redeposition.
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Kim, Choon-Sig. « Soil Carbon Cycling and Soil CO2Efflux in a Red Pine (Pinus densiflora) Stand ». Journal of Ecology and Environment 29, no 1 (1 février 2006) : 23–27. http://dx.doi.org/10.5141/jefb.2006.29.1.023.
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Shepard, James P., et Myron J. Mitchell. « Nutrient Cycling in a Red Pine Plantation Thirty-Nine Years after Potassium Fertilization ». Soil Science Society of America Journal 54, no 5 (septembre 1990) : 1433–40. http://dx.doi.org/10.2136/sssaj1990.03615995005400050037x.
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Compton, Jana E., et Dale W. Cole. « Phosphorus cycling and soil P fractions in Douglas-fir and red alder stands ». Forest Ecology and Management 110, no 1-3 (octobre 1998) : 101–12. http://dx.doi.org/10.1016/s0378-1127(98)00278-3.
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Li, Linhua, Liangshun Xiang, Yan Lin, Lei Chen, Renqing Guo, Yiqi Cao, Xiaohua Huang et Jianbo Wu. « Li/Na Ion Storage Performance of a FeOF Nano Rod with Controllable Morphology ». Processes 10, no 8 (28 juillet 2022) : 1491. http://dx.doi.org/10.3390/pr10081491.
Texte intégralRésumé :
Although the conversion material iron oxyfluoride (FeOF) possesses a high theoretical specific capacity as a cathode material for Li/Na ion batteries, its poor rate and cycling performances, caused mainly by sluggish (Li+/Na+) reaction kinetics, restrict its practical application. Herein, FeOF with high purity, a fusiform nanorod shape and high crystallinity is prepared through a facile chemical solution reaction. The electrochemical measurements show that the present FeOF exhibits high capacity and good cycling stability as a cathode material for Li-ion batteries. Capacities of 301, 274, 249, 222, and 194 mAh/g at stepwise current densities of 20, 50, 100, 200, and 400 mA/g are achieved, respectively. Additionally, the capacity at 100 mA/g retains 123 mAh/g after 140 cycles. Meanwhile, as a cathode material for Na ion battery, it delivers discharge capacities of 185, 167, 151, 134 and 115 mAh/g at stepwise current densities of 20, 50, 100, 200, and 400 mA/g, respectively. A discharge capacity of 83 mAh/g at 100 mA/g is achieved after 140 cycles. The excellent lithium/sodium-storage performance of the present FeOF material is ascribed to its unique nanostructure.
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Holtzclaw, J. David, Maorong Jiang, Zahida Yasin, Clinton H. Joiner et Robert S. Franco. « Rehydration of high-density sickle erythrocytes in vitro ». Blood 100, no 8 (15 octobre 2002) : 3017–25. http://dx.doi.org/10.1182/blood-2002-02-0631.
Texte intégralRésumé :
Recent studies have identified older, low-density sickle red blood cells (SSRBCs) that were resistant to dehydration by valinomycin, a K+ ionophore. These cells, thought to derive from dense SSRBCs that have rehydrated, may represent a terminal cellular phase. To study rehydration, we subjected dense SSRBCs (ρ > 1.107 g/cc) to either oxygenated incubation or rapid oxygenated/deoxygenated (oxy/deoxy) cycling (70 seconds per cycle). Light cells (ρ < 1.087 g/cc) were generated during both oxy incubation (2.9% ± 2.1%; n = 42) and oxy/deoxy cycling (5.3% ± 2.4%; n = 42). The rehydrated cells were K+-depleted (K+ = 20 ± 14 mmol/kg hemoglobin [Hb]) and Na+-loaded (Na+ = 394 ± 106 mmol/kg Hb), and had high levels of external phosphatidylserine. In the presence of external calcium, the generation of rehydrated SSRBCs was inhibited during oxy/deoxy cycling, but the percentage with external phosphatidylserine increased. The calcium-mediated inhibition of rehydration was reversed by charybdotoxin, implying that rehydration was delayed in some cells by the Ca++-activated K+ channel. Preincubation of dense SSRBCs with DIDS (4,4′-di-isothiocyanato-2,2′-disulfostilbene) inhibited the generation of light cells during fast oxy/deoxy cycling, but not during oxy incubation. These results suggest that the sickling-induced pathway, previously implicated in SSRBC dehydration, may be involved in the deoxy-dependent component of rehydration for dense, K+-depleted cells. Light-cell generation was inhibited by 1 mM bumetanide during both oxy incubation and oxy/deoxy cycling, providing evidence that a bumetanide-sensitive, deoxy-independent pathway, previously described in circulating light SSRBCs, also contributes to the rehydration of high-density SSRBCs.
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Schwartz, Robert S., Sylvia Musto, Mary E. Fabry et Ronald L. Nagel. « Two Distinct Pathways Mediate the Formation of Intermediate Density Cells and Hyperdense Cells From Normal Density Sickle Red Blood Cells ». Blood 92, no 12 (15 décembre 1998) : 4844–55. http://dx.doi.org/10.1182/blood.v92.12.4844.
Texte intégralRésumé :
Abstract In sickle cell anemia (SS), some red blood cells dehydrate, forming a hyperdense (HD) cell fraction (>1.114 g/mL; mean corpuscular hemoglobin concentration [MCHC], >46 g/dL) that contains many irreversibly sickled cells (ISCs), whereas other SS red blood cells dehydrate to an intermediate density (ID; 1.090 to 1.114 g/mL; MCHC, 36 to 46 g/dL). This study asks if the potassium-chloride cotransporter (K:Cl) and the calcium-dependent potassium channel [K(Ca2+)] are participants in the formation of one or both types of dense SS red blood cells. We induced sickling by exposing normal density (ND; 1.080 to 1.090 g/mL; MCHC, 32 to 36 g/dL) SS discocytes to repetitive oxygenation-deoxygenation (O-D) cycles in vitro. At physiologic Na+, K+, and Cl−, and 0.5 to 2 mmol/L Ca2+, the appearance of dense cells was time- and pH-dependent. O-D cycling at pH 7.4 in 5% CO2-equilibrated buffer generated only ID cells, whereas O-D cycling at pH 6.8 in 5% CO2-equilibrated buffer generated both ID and HD cells, the latter taking more than 8 hours to form. At 22 hours, 35% ± 17% of the parent ND cells were recovered in the ID fraction and 18% ± 11% in the HD fraction. Continuous deoxygenation (N2/5% CO2) at pH 6.8 generated both ID and HD cells, but many of these cells had multiple projections, clearly different from the morphology of endogenous dense cells and ISCs. Continuous oxygenation (air/5% CO2) at pH 6.8 resulted in less than 10% dense cell (ID + HD) formation. ATP depletion substantially increased HD cell formation and moderately decreased ID cell formation. HD cells formed after 22 hours of O-D cycling at pH 6.8 contained fewer F cells than did ID cells, suggesting that HD cell formation is particularly dependent on HbS polymerization. EGTA chelation of buffer Ca2+ inhibited HD but not ID cell formation, and increasing buffer Ca2+ from 0.5 to 2 mmol/L promoted HD but not ID cell formation in some SS patients. Substitution of nitrate for Cl− inhibited ID cell formation, as did inhibitors of the K:Cl cotransporter, okadaic acid, and [(dihydroindenyl) oxy]alkanoic acid (DIOA). Conversely, inhibitors of K(Ca2+), charybdotoxin and clotrimazole, inhibited HD cell formation. The combined use of K(Ca2+) and K:Cl inhibitors nearly eliminated dense cell (ID + HD cell) formation. In summary, dense cells formed by O-D cycling for 22 hours at pH 7.4 cycling are predominately the ID type, whereas dense cells formed by O-D cycling for 22 hours at pH 6.8 are both the ID and HD type, with the latter low in HbF, suggesting that HD cell formation has a greater dependency on HbS polymerization. A combination of K:Cl cotransport and the K(Ca2+) activities account for the majority of dense cells formed, and these pathways can be driven independently. We propose a model in which reversible sickling-induced K+ loss by K:Cl primarily generates ID cells and K+ loss by the K(Ca2+) channel primarily generates HD cells. These results imply that both pathways must be inhibited to completely prevent dense SS cell formation and have potential therapeutic implications.
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Schwartz, Robert S., Sylvia Musto, Mary E. Fabry et Ronald L. Nagel. « Two Distinct Pathways Mediate the Formation of Intermediate Density Cells and Hyperdense Cells From Normal Density Sickle Red Blood Cells ». Blood 92, no 12 (15 décembre 1998) : 4844–55. http://dx.doi.org/10.1182/blood.v92.12.4844.424k29_4844_4855.
Texte intégralRésumé :
In sickle cell anemia (SS), some red blood cells dehydrate, forming a hyperdense (HD) cell fraction (>1.114 g/mL; mean corpuscular hemoglobin concentration [MCHC], >46 g/dL) that contains many irreversibly sickled cells (ISCs), whereas other SS red blood cells dehydrate to an intermediate density (ID; 1.090 to 1.114 g/mL; MCHC, 36 to 46 g/dL). This study asks if the potassium-chloride cotransporter (K:Cl) and the calcium-dependent potassium channel [K(Ca2+)] are participants in the formation of one or both types of dense SS red blood cells. We induced sickling by exposing normal density (ND; 1.080 to 1.090 g/mL; MCHC, 32 to 36 g/dL) SS discocytes to repetitive oxygenation-deoxygenation (O-D) cycles in vitro. At physiologic Na+, K+, and Cl−, and 0.5 to 2 mmol/L Ca2+, the appearance of dense cells was time- and pH-dependent. O-D cycling at pH 7.4 in 5% CO2-equilibrated buffer generated only ID cells, whereas O-D cycling at pH 6.8 in 5% CO2-equilibrated buffer generated both ID and HD cells, the latter taking more than 8 hours to form. At 22 hours, 35% ± 17% of the parent ND cells were recovered in the ID fraction and 18% ± 11% in the HD fraction. Continuous deoxygenation (N2/5% CO2) at pH 6.8 generated both ID and HD cells, but many of these cells had multiple projections, clearly different from the morphology of endogenous dense cells and ISCs. Continuous oxygenation (air/5% CO2) at pH 6.8 resulted in less than 10% dense cell (ID + HD) formation. ATP depletion substantially increased HD cell formation and moderately decreased ID cell formation. HD cells formed after 22 hours of O-D cycling at pH 6.8 contained fewer F cells than did ID cells, suggesting that HD cell formation is particularly dependent on HbS polymerization. EGTA chelation of buffer Ca2+ inhibited HD but not ID cell formation, and increasing buffer Ca2+ from 0.5 to 2 mmol/L promoted HD but not ID cell formation in some SS patients. Substitution of nitrate for Cl− inhibited ID cell formation, as did inhibitors of the K:Cl cotransporter, okadaic acid, and [(dihydroindenyl) oxy]alkanoic acid (DIOA). Conversely, inhibitors of K(Ca2+), charybdotoxin and clotrimazole, inhibited HD cell formation. The combined use of K(Ca2+) and K:Cl inhibitors nearly eliminated dense cell (ID + HD cell) formation. In summary, dense cells formed by O-D cycling for 22 hours at pH 7.4 cycling are predominately the ID type, whereas dense cells formed by O-D cycling for 22 hours at pH 6.8 are both the ID and HD type, with the latter low in HbF, suggesting that HD cell formation has a greater dependency on HbS polymerization. A combination of K:Cl cotransport and the K(Ca2+) activities account for the majority of dense cells formed, and these pathways can be driven independently. We propose a model in which reversible sickling-induced K+ loss by K:Cl primarily generates ID cells and K+ loss by the K(Ca2+) channel primarily generates HD cells. These results imply that both pathways must be inhibited to completely prevent dense SS cell formation and have potential therapeutic implications.
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Shui, Y., Z. H. Xu, Y. H. Shi et X. Zhou. « Molecular characterization of cyclin B and its expression profile during oogenesis in the red swamp crayfish, Procambarus clarkii (Girard, 1852) (Decapoda, Astacidea) ». Crustaceana 89, no 8 (2016) : 915–31. http://dx.doi.org/10.1163/15685403-00003564.
Texte intégralRésumé :
The maturation promoting factor (MPF), a complex of CDC2 (CDK1) and cyclin B, is a key regulator of controlling the G2/M phase transition in the meiotic maturation of the oocyte in multi-cellular organisms. In this study, full-length cDNA of cyclin B (Pc-cyclin B) from the red swamp crayfish,Procambarus clarkii, was cloned using the degenerate RT-PCR and RACE methods. The cDNA of Pc-cyclin B is 2595 bp in length and encoding a protein of 402 amino acids, with a calculated molecular mass of 45.75 kDa. Six potential cytoplasmic polyadenylation elements (CPE) as well as one signal sequences (AATAAA) were found in the 3′-UTR location. Semi-quantitative RT-PCR analysis revealed that the amount of cyclin B mRNA was highest in the ovary, followed by the heart (); and also significantly higher in the pre-vitellogenesis (pre-Vt) and primary-vitellogenesis (pVt) stages, while low in the tertiary-vitellogenesis and GVBD stages (), suggesting that differential expression of Pc-cyclin B is closely related to oogonial proliferation (mitosis) and oocyte meiotic maturation in this species of crayfish.
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Friedson, Brittany, et Katrina F. Cooper. « Cdk8 Kinase Module : A Mediator of Life and Death Decisions in Times of Stress ». Microorganisms 9, no 10 (15 octobre 2021) : 2152. http://dx.doi.org/10.3390/microorganisms9102152.
Texte intégralRésumé :
The Cdk8 kinase module (CKM) of the multi-subunit mediator complex plays an essential role in cell fate decisions in response to different environmental cues. In the budding yeast S. cerevisiae, the CKM consists of four conserved subunits (cyclin C and its cognate cyclin-dependent kinase Cdk8, Med13, and Med12) and predominantly negatively regulates a subset of stress responsive genes (SRG’s). Derepression of these SRG’s is accomplished by disassociating the CKM from the mediator, thus allowing RNA polymerase II-directed transcription. In response to cell death stimuli, cyclin C translocates to the mitochondria where it induces mitochondrial hyper-fission and promotes regulated cell death (RCD). The nuclear release of cyclin C requires Med13 destruction by the ubiquitin-proteasome system (UPS). In contrast, to protect the cell from RCD following SRG induction induced by nutrient deprivation, cyclin C is rapidly destroyed by the UPS before it reaches the cytoplasm. This enables a survival response by two mechanisms: increased ATP production by retaining reticular mitochondrial morphology and relieving CKM-mediated repression on autophagy genes. Intriguingly, nitrogen starvation also stimulates Med13 destruction but through a different mechanism. Rather than destruction via the UPS, Med13 proteolysis occurs in the vacuole (yeast lysosome) via a newly identified Snx4-assisted autophagy pathway. Taken together, these findings reveal that the CKM regulates cell fate decisions by both transcriptional and non-transcriptional mechanisms, placing it at a convergence point between cell death and cell survival pathways.