Influence of foliar urea on the antioxidant response and fruit color of sweet pepper under limited N supply

BACKGROUND: Foliar fertilizer methods could provide a rapid and efficient response when uptake by plant roots is limited. This work studies the effect of foliar urea sprays (15 g L^?1) at different frequencies on the antioxidant metabolism and fruit quality of sweet pepper fruits under N‐limited nutrient solution (3.5 mmol L^?1 NO₃^?) and fully N‐supplied (12.5 mmol L^?1 NO₃^?) plants. RESULTS: Foliar applications of urea in root N‐limited plants increased the total N concentration in the fruits and no significant differences were found with respect to control fruits (plants fully supplied with N by the roots). Fruit color was significantly affected by the urea sprays, and at the highest frequency (twice a week) the largest overall color difference (ΔE) with respect the non‐sprayed fruits was obtained. Foliar urea increased anthocyanin concentration to control values but flavonoids were only affected at the highest application frequency. N deficiency induced oxidative stress but foliar application of urea altered this response, significantly diminishing catalase and ascorbate peroxidase activity. CONCLUSION: Sweet pepper fruits showed a significant and positive response to foliar fertilization on the studied parameters, compensating to a major extent the reduction of N by the roots. In addition to the environmental issues in reducing N contamination, fully monitored automatically sprayed foliar fertilizer could utilize N more efficiently and at lower cost than applying the full recommended rate of other N fertilizers to the nutrient solution, providing flexibility in correcting N nutrition in the plant, and especially the control of nutrient supply independent of the water supply. Copyright © 2008 Society of Chemical Industry     

The synthesis of a novel 1,8-naphthalimide based PAMAM-type dendron and its potential for light-harvesting

The photophysical characteristics of a PAMAM-type dendron that utilizes a 4-ethoxy-1,8-naphthalimide donor and 4-piperidine-1,8-naphthalimide acceptor in nine organic solvents of different polarities were investigated using absorption and fluorescent spectroscopy. The 1,8-naphthalimide acceptor can be indirectly excited by the donor 1,8-naphthalimide at 372 nm whereby the only emission observed is that due to the acceptor at 517 nm; no acceptor emission at 435 nm was observed. The efficiency of energy transfer was ～98%.     

Quantification of fracture properties and microstructural features of roasted Marcona almonds by image analysis

A method to quantify fracture pattern and microstructural heat damage through image analysis was proposed. The microstructure of Marcona almonds with different degrees of roasting (200 °C; 0, 1.5, 3, 4.5, 6 min) was related with their compression and fracture behaviour. Mechanical tests were performed with a TAXT2 texture analyser. The fracture pattern was characterized by measuring the particle size distribution with image analysis after compression. Light microscopy (LM) and scanning electron microscopy (SEM) were used to observe the changes in the microstructure of the almonds during roasting. The use of image analysis to quantify micro- and macro-structural features proved to be a very useful tool for analysing the crispness/crunchiness behaviour of the samples. The disruption of the inner parenchyma in the samples roasted for longer times proved to be the principal cause of their increased brittleness. The heterogeneity caused by heat degradation contributed to the failure of the material under compression, changing it from a deformable hard solid (raw sample) to a brittle one with enhanced crispy/crunchy characteristics.     

Resting cladoceran eggs and their contribution to zooplankton diversity in a lagoon of the Upper Paraná River floodplain

Zooplankton produce resting eggs and diapause stages as strategies to promote their survival during periods of adverse environmental conditions, thereby ensuring the community diversity. The goal of this study is to investigate the contribution of these eggs, which were present in the sediment of an isolated lagoon in the Upper Paraná River floodplain, to cladoceran diversity. The species hatching from the resting eggs in the sediment do not occur in the plankton. Sediment samples were collected at six sampling sites in the Osmar Lagoon banks, in September 2004 and June, July, August and September 2005. Zooplankton were sampled in the pelagic region, using a motorized pump (1000 L) and plankton net (68 µm). The pH, water temperature (°C), electrical conductivity (µS cm⁻¹) and dissolved oxygen concentration (mg L⁻¹) also were measured. The resting eggs were counted in the laboratory, being maintained under constant temperature and photoperiod until their analyses. The resting eggs were examined daily until hatching. A higher abundance of these eggs was observed in July, during a period of lower temperature and electrical conductivity, and higher pH and dissolved oxygen concentrations. ANOVA results indicated significant differences in resting egg abundance among the sampling months. Ceriodaphnia reticulata, Macrothrix spinosa, Ilyocryptus spinifer, Ephemeroporus tridentatus and Diaphanosoma sp. hatched from the resting eggs, although they were not observed in the plankton samples. C. reticulata was observed for the first time in this floodplain, with these study results corroborating the hypothesis that resting cladoceran eggs do contribute to zooplankton diversity in the lagoon.     

Synthesis, mechanical properties and chemical/solvent resistance of crosslinked poly(aryl-ether-ether-ketones) at high temperatures

A synthetic two-stage procedure was developed for the synthesis of moderately crosslinked polymers based on poly(aryl-ether-ether-ketone) (PEEK). Rigid crosslinks based on aromatic imines were synthetically introduced into PEEK polymer matrix resulting in PEEK materials with various degrees of crosslinking. Two specific crosslinked PEEK polymers (5% and 10% of ketone groups crosslinked) were characterized and studied in detail. Thermomechanical properties, as well as chemical/solvent resistance of these materials at high temperatures (175-280 °C) were investigated and compared to the original PEEK material (Victrex 151G). The introduction of rigid crosslinks was shown to disrupt crystallinity of PEEK very efficiently. Because tensile properties of PEEK depend on its crystallinity, we observed a decrease in properties such as Young's modulus and the ultimate elongation, the extent of which depended on the degree of crosslinking. We also observed an improvement in the elastomeric properties of the crosslinked materials, such as decrease in initial permanent set during high temperature cyclic tensile testing. Mechanical creep behavior at high temperature also improved for crosslinked polymers vs the original commercial Victrex 151G in terms of a reduced irreversible creep component. All crosslinked materials showed excellent resistance to hot oily, acidic and basic environments, as well as excellent thermal stability. Overall, we were able to synthesize “softer” materials that are more rubbery at high temperature than commercial thermoplastic Victrex 151G; these elastomer-like materials showed promising mechanical properties for high temperature applications in hot/corrosive environments.     

Effect of Slaughter Method on Postmortem Changes of Grass Carp (Ctenopharyngodon idella) Stored in Icesti

ABSTRACT: The effect of 2 slaughter methods (immersion in ice-water slurry and electrical stunning followed by ice slurry asphyxiation) on the quality of grass carp ( Ctenopharyngodon idella ) stored in ice for 20 d was evaluated using sensory and chemical analysis. Electricity immediately stunned the fish and did not induce blood spots in the flesh. Fish killed by electricity showed a faster initial rate of ATP degradation and entered into rigor mortis earlier, but did not show significant differences in the sensory score when compared with fish killed by immersion in ice-water slurry. Thus, no differences were observed in the shelf life of carps between the 2 slaughter methods evaluated. The limit for acceptability of grass carp stored in ice was around 13 to 16 d. Grass carp accumulated more inosine than hypoxanthine. K, Ki, P , Fr, and H values were highly correlated with storage time and with the TFRU sensory scores in both groups; these could be used to assess the freshness quality of grass carp.     

Effect of pH,cation concentration and sorbent concentration on cadmium and copper removal by a granular activated carbon

The single adsorption of cadmium and copper from aqueous solutions has been investigated on Darco 12–20 mesh granular activated carbon for a wide range of experimental conditions: pH, metal concentration and carbon concentration. The results showed the efficiency of the activated carbon as sorbent for both metals. Metal removal increases on raising pH and carbon concentration, and decreases on raising the initial metal concentration. The adsorption processes have been modelled using the surface complex formation (SCF) Triple Layer Model (TLM) with a single surface bidentate species or with an overall surface species with fractional stoichiometry. Bidentate stoichiometry considering pH, metal concentration and carbon concentration dependencies successfully predicted cadmium and copper removals for all experimental conditions. The Freundlich isotherm has been also checked. © 1999 Society of Chemical Industry     

Self-esteem and persistence in the face of failure.

In 2 studies, the authors examined self-esteem, persistence, and rumination in the face of failure. Study 1 manipulated degree of failure and availability of goal alternatives. When an alternative was available, high self-esteem (HSE) participants persisted more than low self-esteem (LSE) participants after a single failure, but less after repeated failure. When no alternative was available, no self-esteem differences in persistence emerged. LSE participants ruminated more than HSE participants. Study 2 examined persistence and rumination for 10 personal goals across an academic year. HSE participants were better calibrated (higher within-subject correlations between perceived progress and persistence across goals), had higher overall levels of persistence, higher grade point averages, and lower levels of rumination than LSE participants. Although traditional views that emphasize the tenacious persistence of HSE individuals need revision, HSE people appear more effective in self-regulating goal-directed behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Awareness Support in Distributed Software Development: A Systematic Review and Mapping of the Literature

The developers’ physical dispersion in Distributed Software Development (DSD) imposes challenges related to awareness support during collaboration in such scenario. In this paper, we present a systematic literature review and mapping that gathered, analyzed, and classified studies that improve awareness support in DSD, providing an overview of the area. Our initial search returned 1967 papers, of which 91 were identified as reporting some awareness support to DSD. These papers were then analyzed, and classified according to the 3 C collaboration model and to the Gutwin et al. Awareness Framework. Our findings suggest that awareness in DSD is gaining increasingly attention, 71 out of 91 papers were published from 2006 to 2010. Most part of the papers presented tools with some awareness support. The classification showed that the coordination is by far the most supported dimension of the 3C model, while communication is the less explored. It also showed that workspace awareness elements play a central role on DSD collaboration.