One-step synthesis and solvent-induced exfoliation of hybrid organic-inorganic phyllosilicate-like materials

A room-temperature sol-gel-based process was used to produce by direct synthesis talc-like organosilicates having hexadecyl or aminopropyl groups pending in the interlayer space. Thermal analyses, Fourier transform infrared and 13C/29Si solid-state nuclear magnetic resonance spectroscopies confirmed the presence of organic moieties bonded to the inorganic network. Exfoliation of these organoclays in polar solvents such as water for the positively charged magnesium phyllo(aminopropyl)silicate, and in low polar solvents such as toluene and chloroform for hydrophobic magnesium phyllo(hexadecyl)silicate, was investigated by TEM. The ability of these layered magnesium organosilicates to exfoliate in appropriate solvents was exploited for the preparation of transparent self-supporting films and ordered macroporous networks using by latex colloidal crystal templates.     

Control of salmon oil photo-oxidation during storage in HPMC packaging film: Influence of film colour

The efforts are being made to design protective hydroxypropyl methylcellulose (HPMC) colour packages to avoid photo-oxidation of edible fats and oils. In the present study, edible films of HPMC containing different edible colours like blue, green, yellow, red and white were tested for their ability to avoid photo-oxidation in salmon oil. The samples taken in petri-dishes and covered with coloured HPMC films of thickness 40 μm were placed under fluorescent light at 20 °C. During storage, chemical parameter of oil quality such as fat oxidation was monitored during 8 days of storage. Oxygen consumption by gas chromatography, conjugated diene values by spectrophotometery and fatty acid composition by gas chromatography (GC) was measured. The results of our study show that HPMC films with suitable edible colours act as adequate light barrier to avoid photo-oxidation of salmon oil during extended storage. HPMC films containing white, red and yellow edible colours show good control of oil photo-oxidation almost similar to the control samples stored in darkness. Oil samples treated with blue and green edible films show gradual increase in oil oxidation with increasing time of light exposure. Oxidation behaviour of samples treated with blue and green films was almost similar to the samples stored in transparent films.     

Cassava Starch Coating and Citric Acid to Preserve Quality Parameters of Fresh-Cut “Tommy Atkins” Mango

Abstract: Combination of citric acid dipping (5 g/L) and cassava starch coating (10 g/L), with and without glycerol (10 g/L), was studied to verify the effectiveness of these treatments to inhibit enzymatic browning, to reduce respiration rate, and to preserve quality parameters of “Tommy Atkins” fresh-cut mangoes during storage at 5 °C. Color characteristics (L* and C*), mechanical properties (stress at failure), weight loss, β-carotene content, sensory acceptance, and microbial growth of fruits were evaluated during 15 d. The respiration rate of fruit subjected to the treatments was also analyzed. Nontreated fresh-cut mango was used as a control sample. Cassava starch edible coatings and citric acid dipping promoted a decrease in respiration rate of mango slices, with values up to 41% lower than the control fruit. This treatment also promoted better preservation of texture and color characteristics of mangoes and delayed carotenoid formation and browning reactions during storage. Moreover, the treated fruit showed great sensory acceptance by consumers throughout the whole storage period. However, the use of glycerol in the coating formulation was not efficient in the maintenance of quality parameters of fresh-cut mangoes, promoting a higher weight loss of samples, impairing fruit texture characteristics, increasing carotenogenesis, and favoring microbial growth during storage. Practical Application: Consumer demand for tropical fresh-cut products is increasing rapidly in the world market. Fresh-cut mangoes are appreciated world-wide for its exotic flavor. However, its shelf life is limited by changes in color, texture, appearance, off-flavors and microbial growth. The edible coatings act as gas and water vapor barrier, extending the storage time of fresh-cut fruit and vegetables. Thus, cassava starch is an alternative to preserve minimally processed mangoes and the quality parameters of fresh fruit. The information of this work is useful for the fresh-cut produce industry to increase shelf life of fresh-cut mangoes, which can be considered an alternative to fast food and other ready-to-eat products, attending the demand for healthy and convenient foodstuffs.     

Ecological risk assessment of lead contamination at rifle and pistol ranges using techniques to account for site characteristics

Spent ammunition at outdoor rifle and pistol (RP) firing ranges creates a characteristic pattern of contamination, whereby small areas surrounding backstop berms exhibit extremely high soil lead (Pb) concentrations. We characterized sources, pathways and uncertainty in contaminant accumulation for receptors at two RP ranges in southeastern Ontario. Based on these results, we performed risk calculations using kriging to estimate risk across "worst-case" species foraging ranges. Range-normalized hazard quotients (RNHQ) were then calculated to estimate risk across each receptor's foraging range. Monte Carlo simulation was used to provide +2 standard deviation (SD) risk estimates, in order to account for uncertainty in risk parameters. The American robin was found to be most at risk (RNHQ=4.10; +2SD=9.24), followed by the short-tailed shrew (RNHQ=0.113; +2SD=0.243) and the eastern cottontail (RNHQ=0.109; +2SD=0.703). Elevated risk for the American robin and short-tailed shrew was due to their small foraging ranges and habit of eating earthworms, which bioaccumulate Pb. Elevated risk for the eastern cottontail was due to vegetation accumulating Pb to levels that were considerably higher than conventional bioaccumulation models would indicate. The results of this study clearly emphasize the importance of specific characteristics of RP ranges, such as contamination patterns, dust accumulation on plant tissues, and contaminant bioaccessibility. These characteristics should be accounted for, not only in performing risk assessments, but also in choosing remedial options and in routine management practices.     

P846, a new gadolinium based low diffusion magnetic resonance contrast agent,in characterizing occlusive infarcts,reperfused ischemic myocardium and reperfused infarcts in rats

OBJECT: This study has two objectives: (1) to compare the kinetics of low diffusion P846 with Gd-DOTA using inversion recovery echo planar (IR-EPI) magnetic resonance (MR) imaging and (2) to determine the potential of P846 in defining myocardial viability in hearts subjected to various injuries using T1-weighted spin echo (T1-SE). MATERIALS AND METHODS: Rats were subjected to (1) occlusive infarcts (n = 16), (2) reperfused ischemic injuries (n = 8) or (3) reperfused infarcts (n = 16). A dose of 0.05 mmol/kg P846 was compared to 0.1 mmol/kg Gd-DOTA. IR-EPI and T1-SE images were obtained during 60 min. T(1), DeltaR(1) and DeltaR(1) ratio were measured on IR-EPI. Infarct extents were evaluated on T1-SE and compared with histochemical staining. RESULTS: Blood DeltaR(1) was higher at 5 min after P846 (6.36 +/- 0.32 s(-1)) than after Gd-DOTA (1.30 +/- 0.14 s(-1); P < 0.001). With P846, occlusive infarcts appeared as a hypoenhanced region surrounded by a hyperenhanced rim that lasted for 60 min. The increase in the DeltaR(1) ratio value was slower after P846 than with Gd-DOTA in the reperfused infarcts, suggesting low diffusion/convection of P846. Gd-DOTA homogenously enhanced both occlusive and reperfused infarcts at 30 min. CONCLUSION: P846 provides better contrast and extended discrimination between occlusive and reperfused infarcts compared with Gd-DOTA. The gadolinium dose could be reduced with P846.     

Zebrafish Motile Cilia as a Model for Primary Ciliary Dyskinesia

Zebrafish is a vertebrate teleost widely used in many areas of research. As embryos, they develop quickly and provide unique opportunities for research studies owing to their transparency for at least 48 h post fertilization. Zebrafish have many ciliated organs that include primary cilia as well as motile cilia. Using zebrafish as an animal model helps to better understand human diseases such as Primary Ciliary Dyskinesia (PCD), an autosomal recessive disorder that affects cilia motility, currently associated with more than 50 genes. The aim of this study was to validate zebrafish motile cilia, both in mono and multiciliated cells, as organelles for PCD research. For this purpose, we obtained systematic high-resolution data in both the olfactory pit (OP) and the left–right organizer (LRO), a superficial organ and a deep organ embedded in the tail of the embryo, respectively. For the analysis of their axonemal ciliary structure, we used conventional transmission electron microscopy (TEM) and electron tomography (ET). We characterised the wild-type OP cilia and showed, for the first time in zebrafish, the presence of motile cilia (9 + 2) in the periphery of the pit and the presence of immotile cilia (still 9 + 2), with absent outer dynein arms, in the centre of the pit. In addition, we reported that a central pair of microtubules in the LRO motile cilia is common in zebrafish, contrary to mouse embryos, but it is not observed in all LRO cilia from the same embryo. We further showed that the outer dynein arms of the microtubular doublet of both the OP and LRO cilia are structurally similar in dimensions to the human respiratory cilia at the resolution of TEM and ET. We conclude that zebrafish is a good model organism for PCD research but investigators need to be aware of the specific physical differences to correctly interpret their results.     

Development of a novel framework for the design of transport policies to achieve environmental targets

The formulation of policies requires the selection and configuration of effective and acceptable courses of action to reach explicit goals. A one-size-fits-all policy is unlikely to achieve the desired goals; as a result, the identification of a suite of alternative policies, together with clear indications of their trade-offs, is crucial to accommodate the diversity of stakeholders’ preferences. At present, the formulation of transport policies is done manually; this fact, together with the size of the space of possible policies, results in a large part of that space being left unexplored. A six-step framework to explore the space of alternative transport policies in order to achieve environmental targets is proposed. The process starts with a user-defined set of specific policy measures, using them as building blocks in the generation of alternative policy packages, clusters and future images according to the user's preferences and goals.The analysis framework is based on the visioning and backcasting approach used in the VIBAT report [Banister, D., & Hickman, R. (2006a). Visioning and backcasting for UK transport policy (VIBAT) project. Department for Transport's Horizons Research Programme 2004/06. The Bartlett school of planning and Halcrow Group Ltd. Retrieved 1/18/2008 http://www.ucl.ac.uk/ucft696/vibat2.html]. The framework is being implemented as a prototype decision support system around a case study: the formulation and analysis of policies required to achieve CO₂ emission targets for the transport sector in the UK. Important insights on how to develop the framework have also been elicited from engineering design. The goal is to accelerate the task of policy-making and improve the effectiveness of the resulting policies.The proposed method and computer implementation is fundamentally different from the tools commonly used in the transport sector and is intended to assist (not replace) transport policy makers, and complement (not substitute nor compete with) existing mathematical modelling tools. This research constitutes the first step towards the development of a general family of computer-based systems that support the design of policies to achieve environmental targets—not only for transport, but also for other sectors such as energy and water.     

Direct selection of Pichia pastoris expression strains using new G418 resistance vectors

The methylotrophic yeast, Pichia pastoris, is widely used as a host organism for the expression of heterologous proteins. Currently, the Zeocin and blasticidin resistance genes are the only dominant selectable markers that can be used for primary selection of transformants. In this report we describe new expression vectors that can be used to select directly for P. pastoris transformants using G418 resistance conferred by a modified Tn903kan(r) gene. Compared to other dominant markers, this system is more economical and offers a higher transformation efficiency, due to the small sizes of the cloning vectors, pKAN B and pKANalpha B (GenBank Accession Nos EU285585 and EU285586, respectively). Additionally, multicopy transformants can be generated using these new vectors.     

An Efficient Switching Frequency Limitation Process Applied to a High Dynamic Voltage Supply

This paper presents the analysis and design of a simple and effective switching frequency limitation process with sliding mode synthesis. The control scheme is based on self-oscillating phenomenon which naturally appears in relay feedback systems. Thanks to an analytical study, it shows that the maximum switching frequency of a sliding mode structure can always be limited by adding a simple second order filter in the feedback loop. To illustrate the implementation and the validity of this process, it is applied to a high dynamic voltage supply with a bandwidth of 2000 Hz and with a maximum switching frequency of 15 kHz. According to the experimental results, the switching frequency limitation process shows similar robustness properties to those of sliding mode control when the load and voltage supply change.