Thermo-responsive Diblock Copolymer Worm Gels in Non-polar Solvents

Benzyl methacrylate (BzMA) is polymerized using a poly(lauryl methacrylate) macromolecular chain transfer agent (PLMA macro-CTA) using reversible addition–fragmentation chain transfer (RAFT) polymerization at 70 °C in n-dodecane. This choice of solvent leads to an efficient dispersion polymerization, with polymerization-induced self-assembly (PISA) occurring via the growing PBzMA block to produce a range of PLMA–PBzMA diblock copolymer nano-objects, including spheres, worms, and vesicles. In the present study, particular attention is paid to the worm phase, which forms soft free-standing gels at 20 °C due to multiple inter-worm contacts. Such worm gels exhibit thermo-responsive behavior: heating above 50 °C causes degelation due to the onset of a worm-to-sphere transition. Degelation occurs because isotropic spheres interact with each other much less efficiently than the highly anisotropic worms. This worm-to-sphere thermal transition is essentially irreversible on heating a dilute solution (0.10% w/w) but is more or less reversible on heating a more concentrated dispersion (20% w/w). The relatively low volatility of n-dodecane facilitates variable-temperature rheological studies, which are consistent with eventual reconstitution of the worm phase on cooling to 20 °C. Variable-temperature 1H NMR studies conducted in d26-dodecane confirm partial solvation of the PBzMA block at elevated temperature: surface plasticization of the worm cores is invoked to account for the observed change in morphology, because this is sufficient to increase the copolymer curvature and hence induce a worm-to-sphere transition. Small-angle X-ray scattering and TEM are used to investigate the structural changes that occur during the worm-to-sphere-to-worm thermal cycle; experiments conducted at 1.0 and 5.0% w/w demonstrate the concentration-dependent (ir)reversibility of these morphological transitions

Lower incidence rates but thicker melanomas in Eastern Europe before 1992: A comparison with Western Europe

The objective of this study was to investigate the epidemiology of melanoma across Europe with regard to Breslow thickness and body-site distribution. Incidence data from Cancer Incidence in 5 Continents and the EUROCARE-melanoma database were used: 28 117 melanoma cases from 20 cancer registries in 12 European countries, diagnosed between 1978 and 1992. Regression analysis and general linear modelling were used to analyse the data. Melanomas in Eastern Europe were on average 1.4 mm thicker (P<0.05) than in Western Europe and appeared more often on the trunk. From 1978 to 1992, their Breslow thickness had decreased in Western but not Eastern Europe. There was a latitude gradient in incidence, with highest rates in southern regions in Eastern Europe and an inverse gradient in Western Europe, with highest rates in the North. Mortality:incidence ratios were less favourable in southern parts across Europe, especially in Eastern Europe. If Eastern European populations copy the sunbathing behaviour of the West it is likely that in the near future a higher melanoma incidence can be expected there

Viability of Bifidobacterium longum in cheddar cheese curd during manufacture and storage: effect of microencapsulation and point of inoculation

International audienceThe goal of this study was to assess the effect of methods of inoculation on the viability of probiotic bacteria during cheddar cheese manufacture as well as their stability during storage. Bifidobacterium longum ATCC 15708 was freeze-dried and microencapsulated by spray-coating. The effect of inoculation of free whole cell or microencapsulated cells at three points during manufacture (milk before renneting, at cheddaring or at salting) on the viable counts in cheese and whey was investigated. Microencapsulation had no effect on viable counts, chemical parameters (lactose, lactic acid, total nitrogen, nitrogen soluble in TCA, moisture) or sensory properties during manufacturing or storage of the fresh cheeses for 14 days. Inoculation of the bifidobacteria in milk before renneting resulted in higher viable counts in comparison to other points of inoculation. Bifidobacteria added at the salting step, which survived pressing, were subsequently more stable during storage than those inoculated in milk. The stability of B. longum 15708 during storage was greater in the pressed cheeses that in the free curds. The results of this study provides technological data for cheese makers on the optimum point of inoculation as well as the benefit of pressing the curds in order to ensure high levels of probiotics in fresh cheddar cheese

Urban residential fire and flame injuries: a population based study

Background—Fires are a leading cause of death, but non-fatal injuries from residential fires have not been well characterised. Methods—To identify residential fire injuries that resulted in an emergency department visit, hospitalisation, or death, computerised databases from emergency departments, hospitals, ambulance and helicopter services, the fire department, and the health department, and paper records from the local coroner and fire stations were screened in a deprived urban area between June 1996 and May 1997. Result—There were 131 fire related injuries, primarily smoke inhalation (76%), an incidence of 36 (95% confidence interval (CI) 30 to 42)/100 000 person years. Forty one patients (32%) were hospitalised (11 (95% CI 8 to 15)/100 000 person years) and three people (2%) died (0.8 (95% CI 0.2 to 2.4)/100 000 person years). Injury rates were highest in those 0–4 (68 (95% CI 39 to 112)/100 000 person years) and ≥85 years (90 (95% CI 29 to 213)/100 000 person years). Rates did not vary by sex. Leading causes of injury were unintentional house fires (63%), assault (8%), clothing and nightwear ignition (6%), and controlled fires (for example, gas burners) (4%). Cooking (31%) and smoker's materials (18%) were leading fire sources. Conclusions—Because of the varied causes of fire and flame injuries, it is likely that diverse interventions, targeted to those at highest risk, that is, the elderly, young children, and the poor, may be required to address this important public health problem

Sorption of benzene in cation-exchanged zeolite X, as measured by muon spin relaxation (LF-&mu;SR)

Proton NMR relaxation, diffusion and microimaging techniques were used to investigate the internal structure of calcium alginate gel beads formed by dripping a sodium alginate solution into a calcium chloride solution. It is shown that many of the pore structures previously reported are probably artefacts of sample preparation. Evidence is presented for a non-uniform calcium alginate concentration profile even in beads that have been 'equilibrated' in calcium chloride solution for over 24 h. It is found that the internal structure depends on the ratio of calcium and alginate concentrations and a microstructural phase diagram can be constructed. Copyright (C) 2000 John Wiley & Sons, Ltd