510 research outputs found
Effects of dietary inclusion of Lepidium sativum (garden cress) seed on plasma luteinizing hormone and reproductive performance in female rabbits
Background: Lepidium sativum (LS) has been reported to have multi-purpose medicinal uses. For instance, rubefacient, antihypertensive, hepatoprotective, galactagogue and aphrodisiac properties are well documented; however, there are few controversial reports particularly as related to reproduction. Also, no known study has identified the mechanisms underlying the action of this plant on reproduction. This study was aimed at evaluating the effects of dietary supplementation with LS on luteinizing hormone and reproductive performance in female rabbits.Methods: A total of twenty, nulliparous Chinchilla female rabbits (6.5-month old) were randomly assigned to four treatment groups with five (n=5) rabbits in each group. Diet containing either LS seed powder at 0% (Control), 5%, 7% or 10% were given ad-libitum to female rabbits two weeks pre-pregnancy and throughout the entire period of pregnancy. Blood samples were collected through the marginal ear vein from each female rabbit weekly during pre-pregnancy and pregnancy periods to evaluate Luteinizing hormone (LH). Conception rate, gestation length, litter size, litter weight, number of stillbirths and runts were recorded. Data obtained were analyzed using ANOVA.Results: LS seed inclusion significantly increased (P<0.05) conception rate and plasma LH concentration in dose dependent manner, from 5%- to the 7%- and then decreased at 10%-LS seed level. There was a significant decrease (P<0.05) in gestation length in does fed 10% LS-based diet. Furthermore, the litter weights and number of live kid born were significantly (P<0.05) decreased in all LS groups. In contrast to zero incidence in control rabbits, high incidence of stillbirth and runt were recorded in all LS-based groups.Conclusion: The results show that inclusion of LS seed in rabbit chow increases conception rate and plasma LH levels which were attributed to the phytoestrogens constituent in the seed. Despite the positive role of LS seeds on conception rate and LH, LS seed may possess fetal developmental toxicity effects due to high incidence of stillbirth and extremely low birth weight of newborn recorded.Keywords:Â Lepidium sativum seed, rabbit, reproductive performance, luteinizing hormone, pregnancy, foetu
CD248+ stromal cells are associated with progressive chronic kidney disease
Stromal fibroblasts are the primary cells of the kidney that produce fibrotic matrix. CD248 is a stromal marker expressed on fibroblasts and pericytes within the human kidney. Here, we tested whether CD248 expression in the kidney colocalizes with fibrosis and if it is associated with known determinants of chronic kidney disease (CKD). CD248 expression was located and quantified in situ by immunohistochemistry in kidney biopsies from 93 patients with IgA nephropathy and compared with 22 archived biopsies encompassing normal kidney tissue as control. In normal kidney tissue, CD248 was expressed by resident pericytes, stromal fibroblasts, and was upregulated in human CKD. The expression was linked to known determinants of renal progression. This relationship was maintained in a multivariate analysis with CD248 expression linked to renal survival. CD248 was expressed by a population of α-smooth muscle actin (SMA)+ myofibroblasts and α-SMAâ stromal cells but not expressed on CD45+ leukocytes. Thus, CD248 defines a subset of stromal cells, including but not limited to some myofibroblasts, linked to albuminuria and tubulointerstitial damage during tissue remodeling in CKD
Enhancing the efficiency of PTB7-Th:COi8DFIC-based ternary solar cells with versatile third components
Traditional single-junction binary organic solar cells suffer from narrow absorption windows, limiting their ability to harvest photons. One promising approach to avoid this issue is through the construction of a ternary system to enhance the spectral response and efficiency. However, the complex morphology and photophysical processes within ternary blends leave the criteria of an effective third component unclear, and so they remain a challenge. In this work, we report on the fabrication of PTB7-Th:COi8DFIC-based ternary solar cells with enhanced efficiency by employing either a polymer donor or a nonfullerene acceptor as the third component. We demonstrate that the third component is highly associated with the condensed state of the host acceptor and is the primary factor in determining efficiency improvement. The Ï-Ï stacking molecular packing of COi8DFIC helps to maintain the optimal phase separation within the ternary blends and improves both the hole and electron charge mobilities, resulting in enhanced power conversion efficiency of over 14%, compared to 13.1% in binary devices. We also found an excessive amount of polymer donor or nonfullerene acceptor increases the phase separation and encourages lamellar crystallization with the host acceptor domain, resulting in reduced light-harvesting and external quantum efficiencies at long wavelengths. Our results provide a rational guide to selecting the third component to fabricate high-performance nonfullerene-based ternary solar cells
Perovskites on ice : an additive-free approach to increase the shelf-life of triple-cation perovskite precursor solutions
The development of stable perovskite precursor solutions is critical if solution-processable perovskite solar cells (PSCs) are to be practically manufacturable. Ideally, such precursors should combine high solution stability without using chemical additives that might compromise PSC performance. Here, we show that the shelf-life of high-performing perovskite precursors can be greatly improved by storing solutions at low-temperature without the need to alter chemical composition. We find that devices fabricated from solutions stored for 31-days at 4°C achieve a champion PCE of 18.6% (97% of original PCE). The choice of precursor solvent also impacts solution shelf-life, with DMSO-based solutions having enhanced solution stability compared to those including DMF. We explore the compositions of aged precursors using NMR spectroscopy and analyse films made from these solutions using X-ray diffraction. We conclude that the improvement in precursor solution stability is directly linked to the suppression of an addition-elimination reaction and the preservation of higher amounts of methylammonium within solution
Rapid scalable processing of tin oxide transport layers for perovskite solar cells
The development of scalable deposition methods for perovskite solar cell materials is critical to enable the commercialization of this nascent technology. Herein, we investigate the use and processing of nanoparticle SnO2 films as electron transport layers in perovskite solar cells and develop deposition methods for ultrasonic spray coating and slot-die coating, leading to photovoltaic device efficiencies over 19%. The effects of postprocessing treatments (thermal annealing, UV ozone, and O2 plasma) are then probed using structural and spectroscopic techniques to characterize the nature of the np-SnO2/perovskite interface. We show that a brief âhot air flowâ method can be used to replace extended thermal annealing, confirming that this approach is compatible with high-throughput processing. Our results highlight the importance of interface management to minimize nonradiative losses and provide a deeper understanding of the processing requirements for large-area deposition of nanoparticle metal oxides
Potassium iodide reduces the stability of triple-cation perovskite solar cells
The addition of alkali metal halides to hybrid perovskite materials can significantly impact their crystallisation and hence their performance when used in solar cell devices. Previous work on the use of potassium iodide (KI) in active layers to passivate defects in triple-cation mixed-halide perovskites has been shown to enhance their luminescence efficiency and reduce currentâvoltage hysteresis. However, the operational stability of KI passivated perovskite solar cells under ambient conditions remains largely unexplored. By investigating perovskite solar cell performance with SnO2 or TiO2 electron transport layers (ETL), we propose that defect passivation using KI is highly sensitive to the composition of the perovskiteâETL interface. We reconfirm findings from previous reports that KI preferentially interacts with bromide ions in mixed-halide perovskites, and â at concentrations >5 mol% in the precursor solution â modifies the primary absorber composition as well as leading to the phase segregation of an undesirable secondary non-perovskite phase (KBr) at high KI concentration. Importantly, by studying both material and device stability under continuous illumination and bias under ambient/high-humidity conditions, we show that this secondary phase becomes a favourable degradation product, and that devices incorporating KI have reduced stability
Correlating phase behavior with photophysical properties in mixedâcation mixedâhalide perovskite thin films
Mixed cation perovskites currently achieve very promising efficiency and operational stability when used as the active semiconductor in thinâfilm photovoltaic devices. However, an inâdepth understanding of the structural and photophysical properties that drive this enhanced performance is still lacking. Here the prototypical mixedâcation mixedâhalide perovskite (FAPbI3)0.85(MAPbBr3)0.15 is explored, and temperatureâdependent Xâray diffraction measurements that are correlated with steady state and timeâresolved photoluminescence data are presented. The measurements indicate that this material adopts a pseudocubic perovskite α phase at room temperature, with a transition to a pseudotetragonal ÎČ phase occurring at â260 K. It is found that the temperature dependence of the radiative recombination rates correlates with temperatureâdependent changes in the structural configuration, and observed phase transitions also mark changes in the gradient of the optical bandgap. The work illustrates that temperatureâdependent changes in the perovskite crystal structure alter the charge carrier recombination processes and photoluminescence properties within such hybrid organicâinorganic materials. The findings have significant implications for photovoltaic performance at different operating temperatures, as well as providing new insight on the effect of alloying cations and halides on the phase behavior of hybrid perovskite materials
High-efficiency spray-coated perovskite solar cells utilizing vacuum-assisted solution processing
We use ultrasonic spray-coating to fabricate cesium-containing triple-cation perovskite solar cells with a power-conversion efficiency of up to 17.8%. Our fabrication route involves a brief exposure of the partially wet spray-cast films to a low vacuum, a process that is used to control film crystallization. We show that films that are not vacuum-exposed are relatively rough and inhomogeneous, while vacuum-exposed films are smooth and consist of small and densely packed perovskite crystals. The process techniques developed here represent a step toward a scalable and industrially compatible manufacturing process capable of creating stable and high-performance perovskite solar cells
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