Exploring the neutral invertase–oxidative stress defence connection in Arabidopsis thaliana

Over the past decades, considerable advances have been made in understanding the crucial role and the regulation of sucrose metabolism in plants. Among the various sucrose-catabolizing enzymes, alkaline/neutral invertases (A/N-Invs) have long remained poorly studied. However, recent findings have demonstrated the presence of A/N-Invs in various organelles in addition to the cytosol, and their importance for plant development and stress tolerance. A cytosolic (At-A/N-InvG, At1g35580) and a mitochondrial (At-A/N-InvA, At1g56560) member of the A/N-Invs have been analysed in more detail in Arabidopsis and it was found that At-A/N-InvA knockout plants show an even more severe growth phenotype than At-A/N-InvG knockout plants. The absence of either A/N-Inv was associated with higher oxidative stress defence gene expression, while transient overexpression of At-A/N-InvA and At-A/N-InvG in leaf mesophyll protoplasts down-regulated the oxidative stress-responsive ascorbate peroxidase 2 (APX2) promoter. Moreover, up-regulation of the APX2 promoter by hydrogen peroxide or abscisic acid could be blocked by adding metabolizable sugars or ascorbate. A hypothetical model is proposed in which both mitochondrial and cytosolic A/N-Invs can generate glucose as a substrate for mitochondria-associated hexokinase, contributing to mitochondrial reactive oxygen species homeostasis

Fast dissolving trimethoprim/polyvinyl alcohol nanofibers prepared by electrospinning and evaluation as a new drug delivery system.

Solubility is one of the important parameters to find out desired concentration of drug in systemic circulation for intended pharmacological properties. More than 40% NCEs (new chemical entities) developed in pharmaceutical industry are practically insoluble in water. Any drug to be absorbed must be present in the form of solution at the site of absorption. Hence solubility has turned to a major challenge for formulation scientist. In this research polyvinyl alcohol (PVA) fibers loaded with Trimethoprim (TMP) was fabricated by electrospinning and investigated as potential oral fast-dissolving films. Scanning electron microscopy (SEM) images showed that the fibers take the form of uniform cylinders with smooth surfaces and diameter less than 600 nm, and contain the drugs in the amorphous form. Drug–polymer intermolecular interactions were evidenced by infrared spectroscopy (FT-IR) and differential thermal analysis (DTA). Disintegration and drug released times, when they added to artificial saliva, were 30 s and 90 s respectively and during this time more than 90 % of drug was released. In-vitro bacterial inhibition test was also carried out to determine the relative activity of the released antibiotic. The data reported herein clearly demonstrate that these fast-dissolving films could be suitable candidates for administration of TMP, especially for children, aged people and patients with swallowing difficulties

Study on the effects of the compression ratio and mushy zone heating on the thixotropic microstructure of AA 7075 aluminum alloy via SIMA process

The effects of compression ratios on the microstructure evolution of semisolid Al7075 alloy produced by the strain induced melt activation (SIMA) process were investigated. The samples were cold deformed by compression into the different heights up to 40% reduction. The isothermal holding treatments within mushy zone of the alloy were carried out at 610, 620 and 625 °C for predetermined time intervals. The results revealed that the average grain size gradually reduced with the increase in the compressive ratio. While the compressive ratio surpassed 30%, the descending trend above was not as evident as that of below 30% reduction. The optimum condition presenting the minimum grain size and the maximum shape factor with the highest uniformity is discussed. During the subsequent mushy zone heating, the recrystallization was induced in the deformed samples by the increasingly accumulated strain energy. © 2010 Elsevier B.V. All rights reserved

Effects of Pin Design on Materials Interactions to Friction Stir Spot Joining Aluminium Alloys to Carbon Fibre Reinforced Plastics

No abstract available

Coarsening of equiaxed microstructure in the semisolid state of aluminum 7075 alloy through SIMA processing

In the present study, the coarsening mechanism of equiaxed grains in the semisolid state of aluminum 7075 alloy, treated via strain induced melting activation process, was investigated. The kinetics of equiaxed grain growth in the semisolid state of the experimental alloy was determined. The results revealed that when the holding temperature increased, the coarsening rate constant (K) showed a precipitously increasing character in the range of 590-610 °C. This was attributed to the extensive effect of the coalescence mechanism on the grain growth at the high solid fractions. By further increasing the holding temperature to 620 and 625 °C (increasing the liquid fraction), the effect of coalescence on the grain growth appeared to be weakened, that is, although there was a slight decrease at 620 °C, a gently increasing character could be generally supposed. Severe segregation of Zn and Cu alloying elements at grain boundaries and intragranular droplets was detected at 620 and 625 °C after 15 and 10 min, respectively. © 2011 Springer Science+Business Media, LLC

Effects of Pin Design on Materials Interactions to Friction Stir Spot Joining Aluminium Alloys to Carbon Fibre Reinforced Plastics

No abstract available

Sugars and plant innate immunity

Sugars are involved in many metabolic and signaling pathways in plants. Sugar signals may also contribute to immune responses against pathogens and probably function as priming molecules leading to PAMP-triggered immunity (PTI) and effector-triggered immunity (ETI) in plants. These putative roles also greatly depend on coordinated relationships with hormones and the light status in an intricate network. Although evidences in favor of sugar-mediated plant immunity are accumulating, more in-depth fundamental research is required to unravel the sugar signaling pathways involved. This might pave the way to use biodegradable sugar-(like) compounds to counteract plant diseases, as cheaper and safer alternatives for toxic agrochemicals.status: publishe

Sweet immunity in the plant circadian regulatory network

All organisms have an internal timing mechanism, termed the circadian clock, to anticipate the light/dark cycle. The clock, with an oscillating rhythm that approximates 24 h, is a rather robust system persisting to a great extent in continuous light and dark. It is widely accepted that plant growth and development are regulated by the clock, hormones and sugar signals. On the one hand, sugar signalling can affect circadian rhythms by altering the expression pattern of clock-regulated genes. More in particular, the clock seems to be particularly sensitive to sucrose mediated signalling which is also associated with immunity and abiotic stress responses. Also, hormonal interaction with the clock can contribute to appropriate plant immune responses. Recent data show a prominent role for the clock in growth and stress responses. On the other hand, the clock seems to be essential in controlling the gene expression and activity of an array of carbohydrate metabolizing enzymes, suggesting a complex reciprocal relationship between the clock and metabolic signalling processes. Therefore, the clock fulfills a crucial role at the heart of cellular networks. The players involved in the complex plant circadian network and their possible contribution to the novel “sweet immunity” concept are discussed.status: publishe