711 research outputs found

    Self-organized current transport through low angle grain boundaries in YBa2_2Cu3_3O7δ_{7-\delta} thin films, studied magnetometrically

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    The critical current density flowing across low angle grain boundaries in YBa2_2Cu3_3O7δ_{7-\delta} thin films has been studied magnetometrically. Films (200 nm thickness) were deposited on SrTiO3_3 bicrystal substrates containing a single [001] tilt boundary, with angles of 2, 3, 5, and 7 degrees, and the films were patterned into rings. Their magnetic moments were measured in applied magnetic fields up to 30 kOe at temperatures of 5 - 95 K; current densities of rings with or without grain boundaries were obtained from a modified critical state model. For rings containing 5 and 7 degree boundaries, the magnetic response depends strongly on the field history, which arises in large part from self-field effects acting on the grain boundary.Comment: 8 pages, including 7 figure

    Bench-to-bedside review: Amelioration of acute renal impairment using ethyl pyruvate

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    Inflammation and oxidative stress cause renal impairment. Renal failure exacerbates the effect of oxidative stress on many organ systems. Antioxidants can prevent or treat renal failure in various experimental models and clinical situations. Pyruvate is an endogenous antioxidant with beneficial effects in animal models of oxidative stress. Because sodium pyruvate rapidly degrades in solution, a simple derivative of pyruvic acid, namely ethyl pyruvate, has been investigated as a therapeutic agent in preclinical studies. Ethyl pyruvate reduces organ system damage in ischaemia/reperfusion injury and haemorrhagic and endotoxic shock, at least in part through its antioxidant action. In addition, ethyl pyruvate appears to have direct beneficial effects on cytokine expression and proinflammatory gene regulation. The effect is long lasting and, importantly, even when it is administered after the onset of inflammation it can ameliorate organ damage and improve survival. Ethyl pyruvate is a widely used as a food additive and was shown to be safe in phase I clinical trials. We suggest ethyl pyruvate warrants further evaluation in the management of acute renal impairment

    Photochemistry of framework-supported M(diimine)(CO)₃X complexes in 3D Lithium-Carboxylate metal−organic frameworks: monitoring the effect of framework cations

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    The structures and photochemical behaviour of two new metal-organic frameworks are reported. Reaction of Re(2,2ʹ-bipyʹ-5,5ʹ-dicarboxylic acid)(CO)₃Cl or Mn(2,2ʹ-bipyʹ-5,5ʹ- dicarboxylic acid)(CO)₃Br with either LiCl or LiBr, respectively, produces single crystals of {Li₂(DMF)₂[(2,2ʹ-bipyʹ-5,5ʹ-dicarboxylate)Re(CO)₃Cl]}n (ReLi) or {Li₂(DMF)₂[(2,2ʹ-bipyʹ- 5,5ʹ-dicarboxylate)Mn(CO)₃Br]}n (MnLi). The structures formed by the two MOFs comprise one-dimensional chains of carboxylate-bridged Li(I) cations that are cross-linked by units of Re(2,2ʹ-bipyʹ-5,5ʹ-dicarboxylate)(CO)₃Cl (ReLi) or Mn(2,2ʹ-bipyʹ-5,5ʹ- dicarboxylate)(CO)₃Br (MnLi). The photophysical and photochemical behaviour of both ReLi and MnLi are probed. The rhenium-containing MOF, ReLi, exhibits luminescence and the excited state behaviour, as established by time-resolved infra-red measurements, are closer in behaviour to that of unsubstituted [Re(bipy)(CO)₃Cl] rather than a related MOF where the Li(I) cations are replaced by Mn(II) cations. These observations are further supported by DFT calculations. Upon excitation MnLi forms a dicarbonyl species which rapidly recombines with the dissociated CO, in a fashion consistent with the majority of the photoejected CO not escaping the MOF channels

    Basal cell nuclear size in experimental oral mucosal carcinogenesis.

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    It has been suggested that the size of the nuclei of epithelial basal cells can be used in predicting the likelihood of malignant transformation of epithelium. This proposition was assessed in rat palatal epithelium after the carcinogen 4-nitroquinoline-1-oxide had been applied to the epithelium for varying periods of time. No consistent alterations in basal cell nuclear size, including area, perimeter, diameter and regularity of form were found with routine light microscopy as the epithelium passed through various stages of dysplasia to carcinoma. This finding casts doubt on the value of using a variation of basal cell nuclear size as a predictor of malignant transformation

    Causal effects of an absent crowd on performances and refereeing decisions during Covid-19

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    The Covid-19 pandemic has induced worldwide natural experiments on the effects of crowds. We exploit one of these experiments that took place over several countries in almost identical settings: professional football matches played behind closed doors within the 2019/20 league seasons. We find large and statistically significant effects on the number of yellow cards issued by referees. Without a crowd, fewer cards were awarded to the away teams, reducing home advantage. These results have implications for the influence of social pressure and crowds on the neutrality of decisions

    Targeting reactive oxygen species (ROS) to combat the age-related loss of muscle mass and function.

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    The loss of muscle mass and function with age, termed sarcopenia, is an inevitable process, which has a significant impact on quality of life. During ageing we observe a progressive loss of total muscle fibres and a reduction in cross-sectional area of the remaining fibres, resulting in a significant reduction in force output. The mechanisms which underpin sarcopenia are complex and poorly understood, ranging from inflammation, dysregulation of protein metabolism and denervation. However, there is significant evidence to demonstrate that modified ROS generation, redox dis-homeostasis and mitochondrial dysfunction may have an important role to play. Based on this, significant interest and research has interrogated potential ROS-targeted therapies, ranging from nutritional-based interventions such as vitamin E/C, polyphenols (resveratrol) and targeted pharmacological compounds, using molecules such as SS-31 and MitoQ. In this review we evaluate these approaches to target aberrant age-related ROS generation and the impact on muscle mass and function

    Abstracts of presentations on plant protection issues at the xth international congress of virology: August 11-16, 1996 Binyanei haOoma, Jerusalem Iarael part 3(final part)

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