Fluorescent magnetic hybrid nanoprobe for multimodal bioimaging

A fluorescent magnetic hybrid imaging nanoprobe (HINP) was fabricated by the conjugation of superparamagnetic Fe3O4 nanoparticles and visible light emitting (～600 nm) fluorescent CdTe/CdS quantum dots (QDs). The assembly strategy used the covalent linking of the oxidized dextran shell of magnetic particles to the glutathione ligands of QDs. The synthesized HINP formed stable water-soluble colloidal dispersions. The structure and properties of the particles were characterized by transmission electron and atomic force microscopy, energy dispersive x-ray analysis and inductively coupled plasma optical emission spectroscopy, dynamic light scattering analysis, optical absorption and photoluminescence spectroscopy, and fluorescent imaging. The luminescence imaging region of the nanoprobe was extended to the near-infrared (NIR) (～800 nm) by conjugation of the superparamagnetic nanoparticles with synthesized CdHgTe/CdS QDs. Cadmium, mercury based QDs in HINP can be easily replaced by novel water-soluble glutathione stabilized AgInS2/ZnS QDs to present a new class of cadmium-free multimodal imaging agents. The observed NIR photoluminescence of fluorescent magnetic nanocomposites supports their use for bioimaging. The developed HINP provides dual-imaging channels for simultaneous optical and magnetic resonance imaging.     

A genetic screen for yeast genes induced by sustained osmotic stress

The budding yeast, Saccharomyces cerevisiae, responds to changes in external osmolarity through the activation of an osmosensing signal transduction pathway. Using lacZ-reporter gene fusions, clonal cell lines were screened for levels of beta-galactosidase activity in the presence or absence of osmotic stress. A screen of 9,000 transformants displayed 663 (7%) gene fusions that were active in rich medium. Each of the transformants were also assayed for gene activity 24 h following a transfer to high osmolarity medium (0.6 M NaCl) and of the 9,000 clonal cell lines, 86 (1%) displayed a decrease in expression, and seven (0.1%) displayed a reproducible increase in gene expression during primary screening. The chromosomal loci of the lacZ insertions were determined, and the gene(s) associated with that site was examined for osmotically induced expression using RNA blot analysis. Five stress-activated genes were analysed by RNA blot: YDL222C, NMD2, PTC7, FAA4 and YRF1. The genes identified by this screen encompass cellular adaptations to stress including signal transduction, protein myristoylation and fatty acid/sphingolipid content in the cell membrane.     

Equivalence salting and temporal dominance of sensations analysis for different sodium chloride substitutes in cream cheese

The purpose of the study was to determine the potency and equivalence of salt substitutes (potassium chloride, magnesium chloride, monosodium glutamate, potassium lactate, calcium lactate and potassium phosphate monobasic) in cream cheese and to evaluate sensory flavour profiles. The methods used were magnitude estimation and temporal dominance of sensations (TDS). Equivalent salting of cream cheese containing 1% sodium chloride was obtained using: 1.2% potassium chloride, 2.56% monosodium glutamate, 2.5% magnesium chloride and 2.98% potassium phosphate. The TDS revealed that, other than salty taste, the most significant flavours produced were sour and bitter. The potencies of salt substitutes are much lower than that of sodium chloride.     

Nanocomposites based on ionene–bentonite used to treat oily water

A large number of processes are used to treat the oily water (oil emulsions in water) produced in the petroleum industry. The treatment strategy depends not only on the strictness of the environmental requirements in the jurisdiction where the water is discharged, but also on the relative treatment cost. The present study reports tests to assess the effectiveness of removing oil from oily water by adsorption in polymer nanocomposites. These composites were prepared from ionenes (cationic polyelectrolytes) and sodium bentonite or organophilic bentonite. They were characterized by infrared spectrometry, thermogravimetry, X‐ray fluorescence, and X‐ray diffraction. The oil‐removal effectiveness was evaluated by mixing nanocomposites and oily water in a shaker bath (batch test). In the tests conducted only with treated sodium bentonite and organophilic bentonite, the oil removal was ～ 70%, whereas the use of polymer nanocomposites raised the adsorption of oil to ～ 90%. These values depended on the mass of material, concentration of oil in the contaminated water, and the contact time. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Hydration of C3S thin films

Thin films of C₃S of a few tens of nanometers were produced by electron beam evaporation. After verification that the chemical composition of the bulk material remained unchanged, the samples were hydrated with water vapor in a reaction chamber under saturated pressure and temperature conditions, and were kept isolated from atmospheric exposure throughout the whole duration of the experiment. Analyses by X-ray photoelectron spectroscopy at different stages of hydration evidence a shift of the Si peaks to higher energies and a subsequent decrease of the Ca–Si binding energy distance, indicating silicate polymerization expected upon formation of C–S–H. The measured molar Ca/Si ratio evolves from that of a jennite-like material, of about 1.55, at the beginning of the experiment (attributed to pre-hydration of the thin films), to a tobermorite-like ratio of 0.85 after 3 h of hydration.     

Kinetic study for the development of an accelerated oxidative stability test to estimate virgin olive oil potential shelf life

This study proposes an accelerated test performed at mild temperature (40–60 °C) to measure oxidative stability and estimate the potential shelf life of extra‐virgin olive oil (EVOO). The kinetic behavior of normalized oxidation indices (PV, K₂₃₂ and K₂₇₀) and the oxidizing substrate [unsaturated fatty acids (UFA)] during storage of different virgin olive oil samples in darkness and at different temperatures (25–60 °C) is reported for the first time. PV and K₂₃₂ followed an apparent pseudo zero‐order kinetics (R² >0.951) at all the experimental temperatures in all samples, whereas the evolution of K₂₇₀ apparently better fitted a pseudo first‐order kinetics (R² >0.926). The temperature‐dependent kinetics of the oxidation indices and the UFA were well described by the linear Arrhenius equation between 25 and 60 °C (0.960< R² <0.999, p <0.05). The best correlation between loss of PUFA and increase of oxidation product indices was K₂₃₂ (0.581< R² <0.924). The time required to reach the upper limits for PV, K₂₃₂ and K₂₇₀ established for the EVOO category in the current EU legislation correlated well with temperature using a potential equation, making it possible to set up an accelerated stability test at temperatures below 60 °C to estimate the potential shelf life under normal storage temperature conditions.     

Pattern of serum protein fractions in dairy cows during different stages of gestation and lactation

In dairy cows the period of transition from late gestation to early lactation is recognized as inducing considerable metabolic adaptation. The aim of this study was to analyse modifications in serum protein values occurring during the dry and the transition period and during lactation in a group of five Holstein cows of high average milk production. For all subjects, selected on the basis of their pregnancy status, blood samples were collected at different physiological phases: dry period (-60, -30 d to calving), transition period (almost 7 d to calving, 7 d after calving), and lactation (weeks 2, 5 and 15 after calving), for a total of eight blood samples for each cow. On each blood sample total proteins and electrophoresis analysis were performed. On the data obtained, normally distributed (P<0·05, Kolmogorov-Smirnov's test), one-way Repeated Measure Analysis of Variance (ANOVA), was applied to evaluate the influence of different stages of gestation and lactation on the considered parameters. Results showed a significant effect on total proteins, α1-globulins, β-globulins, γ-globulins and albumin/globulin ratio. Most of the detected modifications were related to the transition from gestation to lactation, indicating that it is a period of great metabolic stress for cows. On the basis of the obtained results we can affirm that the pattern of serum protein fraction rn could give information about dehydration, plasma volume expansion and hepatic function occurring during the peripartum period in dairy cows.     

Biochemical composition of two red seaweed species grown on the Brazilian coast

BACKGROUND: Algae species have been used as an important source of food because they are highly nutritive considering their vitamin, protein, mineral, fiber, essential fatty acid and carbohydrate contents. However, a large number of seaweeds have been poorly studied, especially Brazilian species. Two red macroalgae species from the Brazilian coast (Plocamium brasiliense and Ochtodes secundiramea) were assessed with respect to their total lipid, fatty acid, total nitrogen, protein, amino acid and total carbohydrate contents. RESULTS: The total lipid contents (dry weight) were 36.3 and 35.4 g kg^?1; fatty acid contents were 9.3 and 12.1 g kg^?1; total nitrogen contents were 37.4 and 24.9 g kg^?1; protein contents were 157.2 and 101.0 g kg^?1; amino acid contents were 127.5 and 91.4 g kg^?1; and total carbohydrate contents were 520.3 and 450.7 g kg^?1 for P. brasiliense and O. secundiramea, respectively. CONCLUSION: Considering these compositions, both algae species were determined to have sources of protein, essential amino acids and carbohydrates similar to the edible seaweeds Laminaria japonica and Palmaria palmata. Copyright © 2011 Society of Chemical Industry     

Anthropogenic forcing of estuarine hypoxic events in sub-tropical catchments: landscape drivers and biogeochemical processes

Episodic hypoxic events can occur following summer floods in sub-tropical estuaries of eastern Australia. These events can cause deoxygenation of waterways and extensive fish mortality. Here, we present a conceptual model that links key landscape drivers and biogeochemical processes which contribute to post-flood hypoxic events. The model provides a framework for examining the nature of anthropogenic forcing. Modification of estuarine floodplain surface hydrology through the construction of extensive drainage networks emerges as a major contributing factor to increasing the frequency, magnitude and duration of hypoxic events. Forcing occurs in two main ways. Firstly, artificial drainage of backswamp wetlands initiates drier conditions which cause a shift in vegetation assemblages from wetland-dominant species to dryland-dominant species. These species, which currently dominate the floodplain, are largely intolerant of inundation and provide abundant labile substrate for decomposition following flood events. Decomposition of this labile carbon pool consumes oxygen in the overlying floodwaters, and results in anoxic conditions and waters with excess deoxygenation potential (DOP). Carbon metabolism can be strongly coupled with microbially-mediated reduction of accumulated Fe and Mn oxides, phases which are common on these coastal floodplain landscapes. Secondly, artificial drainage enhances discharge rates during the flood recession phase. Drains transport deoxygenated high DOP floodwaters rapidly from backswamp wetlands to the main river channel to further consume oxygen. This process effectively displaces the natural carbon metabolism processes from floodplain wetlands to the main channel. Management options to reduce the impacts of post-flood hypoxia include i) remodifying drainage on the floodplain to promote wetter conditions, thereby shifting vegetation assemblages towards inundation-tolerant species, and ii) strategic retention of floodwaters in the backswamp wetlands to reduce the volume and rate during the critical post-flood recession phase.