Synthesis of well-dispersed nanoparticles within porous solid structures using surface-tethered surfactants in supercritical CO2

We have developed a new method for the synthesis of Pd nanoparticles with controllable sizes within a silica matrix using solid-supported surfactants in supercritical CO2. XRD, HRTEM and CO chemisorption data show that unformly sized Pd nanoparticles are evenly distributed within the porous silica and are chemically tethered by surfactant molecules [poly(oxyethylene stearyl ether) and fluorinated poly(oxyethylene)]. It is postulated that tiny solid-supported surfactant assemblies act as nano-reactors for the template synthesis of nanoparticles or clusters from the soluble precursors therein.

Aerogel-coated metal nanoparticle colloids as novel entities for the synthesis of defined supported metal catalysts

Nanometer metal particles of tailored size (3-5 nm) and composition prepared via inverse microemulsion were encapsulated by ultrathin coatings (<2.5 nm) of inorganic porous aerogels covered with surface -OH groups. These composite materials formed metastable colloids in solvent(s), and the organic surfactant molecules were subsequently removed without leading to aggregation (the ethanolic colloid solution was shown to be stable against flocculation for at least weeks). We demonstrate that the totally inorganic-based composite colloids, after the removal of surfactant, can be anchored to conventional solid supports (gamma-alumina, carbons) upon mixing. Application of a high temperature resulted in the formation of strong covalent linkages between the colloids and the support because of the condensation of surface groups at the interface. Detailed characterizations (X-ray diffraction (XRD), pore analysis, transmission electron microscopy (TEM), CO chemisorption) and catalytic testing (butane combustion) showed that there was no significant metal aggregation from the fine metal particles individually coated with porous aerogel oxide. Most of these metal sites on the coated nanoparticles with and without support are fully accessible by small molecules hence giving extremely active metal catalysts. Thus, the product and technology described may be suitable to synthesize these precursor entities of defined metal sizes (as inks) for wash coat/impregnation applications in catalysis. The advantages of developing inorganic nanocomposite chemical precursors are also discussed.

Fatty acids and immune function: new insights into mechanisms

Fatty acids are known to play diverse roles in immune cells. They are important as a source of energy, as structural components of cell membranes, as signaling molecules and as precursors for the synthesis of eicosanoids and similar mediators. Recent research has suggested that the localization and organisation of fatty acids into distinct cellular pools has a direct influence on the behaviour of a number of proteins involved in immune cell activation, including those associated with T cell responses, antigen presentation and fatty acid-derived inflammatory mediator production. This article reviews these studies and places them in the context of existing literature in the field. These studies indicate the existence of several novel mechanisms by which altered fatty acid availability can modulate immune responses and impact upon clinical outcomes

Fatty acids as gatekeepers of immune cell regulation

Fatty acids have diverse roles in all cells. They are important as a source of energy, as structural components of cell membranes, as signalling molecules and as precursors for the synthesis of eicosanoids. Recent research has suggested that the organization of fatty acids into distinct cellular pools has a particularly important role in cells of the immune system and that forms of lipid trafficking exist, which are as yet poorly understood. This Review examines the nature and regulation of cellular lipid pools in the immune system, their delivery of fatty acids or fatty acid derivatives to specific locations and their potential role in health and disease.

Lipids and the immune response: from molecular mechanisms to clinical applications

Purpose of review This review critically evaluates recent studies investigating the effects of fatty acids on immune and inflammatory responses in both healthy individuals and in patients with inflammatory diseases, with some reference to animal studies where relevant. It examines recent findings describing the cellular and molecular basis for the modulation of immune function by fatty acids. The newly emerging area of diet-genotype interactions will also be discussed, with specific reference to the anti-inflammatory effects of fish oil. Recent findings Fatty acids are participants in many intracellular signalling pathways. They act as ligands for nuclear receptors regulating a host of cell responses, they influence the stability of lipid rafts, and modulate eicosanoid metabolism in cells of the immune system. Recent findings suggest that some or all of these mechanisms may be involved in the modulation of immune function by fatty acids. Summary Human studies investigating the relationship between dietary fatty acids and some aspects of the immune response have been disappointingly inconsistent. This review presents the argument that most studies have not been adequately powered to take into account the influence of variation (genotypic or otherwise) on parameters of immune function. There is well-documented evidence that fatty acids modulate T lymphocyte activation, and recent findings describe a range of potential cellular and molecular mechanisms. However, there are still many questions remaining, particularly with respect to the roles of nuclear receptors, for which fatty acids act as ligands, and the modulation of eicosanoid synthesis, for which fatty acids act as precursors.

Changes in free amino acids and sugars in potatoes due to sulfate fertilization and the effect on acrylamide formation

To examine how sulfur deprivation may affect acrylamide formation in cooked potatoes, three varieties of potato were grown under conditions of either severe sulfur deprivation or an adequate supply of sulfur. In all three varieties sulfur deprivation led to a decrease in acrylamide formation, even though the levels of sugars, which are acrylamide precursors, were higher in tubers of the sulfur-deprived plants. In one variety the concentration of free asparagine, the other precursor for acrylamide, was also higher. There was a very close correlation between the concentration of asparagine in the tubers expressed as a proportion of the total free amino acid pool and the formation of acrylamide upon cooking, whereas sugars were poorly correlated with acrylamide. In potatoes, where concentrations of sugars are usually limiting, competition between asparagine and other amino acids participating in the Maillard reaction may be a key determinant of the amount of acrylamide that is formed during processing.

Polymer-drug conjugates: current status and future trends

Polymer conjugates are nano-sized, multicomponent constructs already in the clinic as anticancer compounds, both as single agents or as elements of combinations. They have the potential to improve pharmacological therapy of a variety of solid tumors. Polymer-drug conjugation promotes passive tumor targeting by the enhanced permeability and retention (EPR) effect and allows for lysosomotropic drug delivery following endocytic capture. In the first part of this review, we analyze the promising results arising from clinical trials of polymer-bound chemotherapy. The experience gained on these studies provides the basis for the development of a more sophisticated second-generation of polymer conjugates. However, many challenges still lay ahead providing scope to develop and refine this field. The "technology platform'' of polymer therapeutics allows the development of both new and exciting polymeric materials, the incorporation of novel bioactive agents and combinations thereof to address recent advances in drug therapy. The rational design of polymer drug conjugates is expected to realize the true potential of these "nanomedicines".

Social factors and postpartum depression in Khayelitsha, Cape Town

Social factors, including poverty, are known risk factors for depression. In a previous study conducted in Khayelitsha, a very poor peri-urban settlement near Cape Town, a 34.7% prevalence rate for postpartum depression was found, roughly three times the expected rate internationally. This article is a report on a logistical regression analysis, showing that the odds ratios for the probability of maternal depression at two months were: for the infant being unwanted, OR=4.33, 95% CI: (1.75; 11.60); for the father's negative attitude towards the infant, OR=6.03, 95% CI: (2.01; 20.09); and for the mother cohabiting with (as opposed to not living with) a male partner, OR=2.77, 95% CI: (1.08; 7.69). The odds ratios for the probability of the mother being insensitive towards the infant at two months were: for the mother aged 20 to 24 years, OR=0.40, 95% CI: (0.10; 1.42); for the mother aged 25 to 29 years, OR=0.24, 95% CI: (0.06; 0.77); for the mother aged 30 years or older, OR=0.27, 95% CI: (0.07; 0.90); and for the mother receiving no help from her partner, OR=2.12, 95% CI: (1.05; 4.33). Since data were collected cross-sectionally, it is not possible to draw conclusions about causal pathways. The findings support further investigation into the precursors of, and risk factors for, postpartum depression amongst poor South African women.

Socioemotional development in adolescents at risk for depression: the role of maternal depression and attachment style

We examined the impact on adolescent socioemotional functioning of maternal postnatal depression (PND) and attachment style. We also investigated the role of earlier aspects of the child's development-attachment in infancy, and 5-year representations of family relationships. Ninety-one mother-child pairs, recruited in the postnatal period, were followed tip at 13 years. Adolescents were interviewed about their friendships, and their level of emotional sensitivity and maturity were rated. Emotional sensitivity was heightened in girls whose mothers experienced PND; notably, its occurrence was also linked to insecure attachment in infancy and raised awareness of emotional components of family relationships at 5 years. High emotional sensitivity was also associated with adolescent depressed mood. Raised social maturity was predicted by a secure maternal attachment style and, for girls, by exposure to maternal PND. Precursors of adolescent social maturity were evident in the narrative coherence of 5-year family representations. Higher social maturity in the friendship interview was also associated with overall good adjustment.

The SAFEE on-board threat detection system

Under the framework of the European Union Funded SAFEE project(1), this paper gives an overview of a novel monitoring and scene analysis system developed for use onboard aircraft in spatially constrained environments. The techniques discussed herein aim to warn on-board crew about pre-determined indicators of threat intent (such as running or shouting in the cabin), as elicited from industry and security experts. The subject matter experts believe that activities such as these are strong indicators of the beginnings of undesirable chains of events or scenarios, which should not be allowed to develop aboard aircraft. This project aimes to detect these scenarios and provide advice to the crew. These events may involve unruly passengers or be indicative of the precursors to terrorist threats. With a state of the art tracking system using homography intersections of motion images, and probability based Petri nets for scene understanding, the SAFEE behavioural analysis system automatically assesses the output from multiple intelligent sensors, and creates. recommendations that are presented to the crew using an integrated airborn user interface. Evaluation of the system is conducted within a full size aircraft mockup, and experimental results are presented, showing that the SAFEE system is well suited to monitoring people in confined environments, and that meaningful and instructive output regarding human actions can be derived from the sensor network within the cabin.

Tracking and mean structure of easterly waves over the Intra-Americas Sea

Easterly waves (EWs) are prominent features of the intertropical convergence zone (ITCZ), found in both the Atlantic and Pacific during the Northern Hemisphere summer and fall, where they commonly serve as precursors to hurricanes over both basins.Alarge proportion of Atlantic EWs are known to form over Africa, but the origin of EWs over the Caribbean and east Pacific in particular has not been established in detail. In this study reanalyses are used to examine the coherence of the large-scale wave signatures and to obtain track statistics and energy conversion terms for EWs across this region. Regression analysis demonstrates that some EW kinematic structures readily propagate between the Atlantic and east Pacific, with the highest correlations observed across Costa Rica and Panama. Track statistics are consistent with this analysis and suggest that some individual waves are maintained as they pass from the Atlantic into the east Pacific, whereas others are generated locally in the Caribbean and east Pacific. Vortex anomalies associated with the waves are observed on the leeward side of the Sierra Madre, propagating northwestward along the coast, consistent with previous modeling studies of the interactions between zonal flow and EWs with model topography similar to the Sierra Madre. An energetics analysis additionally indicates that the Caribbean low-level jet and its extension into the east Pacific—known as the Papagayo jet—are a source of energy for EWs in the region. Two case studies support these statistics, as well as demonstrate the modulation of EW track and storm development location by the MJO.

Regioselective Beckmann rearrangements of furanoside and pyranoside-derived oximes

The Beckmann rearrangement is a useful reaction employed to provide access to amides from oxime substrates. Applied to cyclic structures, the Beckmann rearrangement leads to ring expansion and allows access to cyclic lactams. Our investigations focused upon the synthesis of glycoside-derived lactams from oxime precursors. In probing a range of conditions, we observed that 2,4,6-trichloro[1,3,5]triazine (TCT) was an effective and mild promoter of the rearrangement affording pyrano- and heptanoside lactam products with excellent regioselectivities.

Free amino acids and sugars in rye grain: implications for acrylamide formation

Acrylamide forms from free asparagine and sugars during cooking, and products derived from the grain of cereals, including rye, contribute a large proportion of total dietary intake. In this study, free amino acid and sugar concentrations were measured in the grain of a range of rye varieties grown at locations in Hungary, France, Poland, and the United Kingdom and harvested in 2005, 2006, and 2007. Genetic and environmental (location and harvest year) effects on the levels of acrylamide precursors were assessed. The data showed free asparagine concentration to be the main determinant of acrylamide formation in heated rye flour, as it is in wheat. However, in contrast to wheat, sugar, particularly sucrose, concentration also correlated both with asparagine concentration and with acrylamide formed. Free asparagine concentration was shown to be under genetic (G), environmental (E), and integrated (G × E) control. The same was true for glucose, whereas maltose and fructose were affected mainly by environmental factors and sucrose was largely under genetic control. The ratio of variation due to varieties (genotype) to the total variation (a measure of heritability) for free asparagine concentration in the grain was 23%. Free asparagine concentration was closely associated with bran yield, whereas sugar concentration was associated with low Hagberg falling number. Rye grain was found to contain much higher concentrations of free proline than wheat grain, and less acrylamide formed per unit of asparagine in rye than in wheat flour.

Ultrafast charge separation in a photoreactive rhenium-appended porphyrin assembly monitored by picosecond transient infrared spectroscopy

Rhenium(bipyridine)(tricarbonyl)(picoline) units have been linked covalently to tetraphenylmetalloporphyrins of magnesium and zinc via an amide bond between the bipyridine and one phenyl substituent of the porphyrin. The resulting complexes, abbreviated as [Re(CO)(3)(Pic)Bpy-MgTPP][OTf] and [Re(CO)(3)(Pic)Bpy-ZnTPP][OTf], exhibit no signs of electronic interaction between the Re(CO)(3)(bpy) units and the metalloporphyrin units in their ground states. However, emission spectroscopy reveals solvent-dependent quenching of porphyrin emission on irradiation into the long-wavelength absorption bands localized on the porphyrin. The characteristics of the excited states have been probed by picosecond time-resolved absorption (TRVIS) spectroscopy and time-resolved infrared (TRIR) spectroscopy in nitrile solvents. The presence of the charge-separated state involving electron transfer from MgTPP or ZnTPP to Re(bpy) is signaled in the TRIR spectra by a low-frequency shift in the nu(CO) bands of the Re(CO)(3) moiety similar to that observed by spectroelectrochemical reduction. Long-wavelength excitation of [Re(CO)(3)(Pic)Bpy-MTPP][OTf] results in characteristic TRVIS spectra of the S-1 state of the porphyrin that decay with a time constant of 17 ps (M = Mg) or 24 ps (M = Zn). The IR bands of the CS state appear on a time scale of less than 1 ps (Mg) or ca. 5 ps (Zn) and decay giving way to a vibrationally excited (i.e., hot) ground state via back electron transfer. The IR bands of the precursors recover with a time constant of 35 ps (Mg) or 55 ps (Zn). The short lifetimes of the charge-transfer states carry implications for the mechanism of reaction in the presence of triethylamine.

Electronic energy transfer in a dinuclear Ru/Os complex containing a photoresponsive dithienylethene derivative as bridging ligand

In order to build up a multicomponent system able to perform useful light-induced functions, a dithienylethene-bridged heterodinuclear metal complex (Ru/Os) has been prepared. The compound was characterized and its photophysical properties studied in detail.