An investigation into the antimicrobial mechanisms of action of two contact lens biocides using electron microscopy.

Polyquaternium-1 (PQ-1) and myristamidopropyl dimethylamine (MAPD) are biocides used commercially in a contact lens disinfecting solutions. Electron microscopy was used to provide further evidence on the mechanism(s) of action of these agents against a wide range of ocular pathogens including bacteria, fungi and protozoa. Both PQ-1 and MAPD caused multiple forms of damage to the organisms tested, evidenced by structural alterations, blebbing, leakage and cell destruction. The extent of damage and the selectivity against specific type of microorganisms was consistent with the antimicrobial activity of these agents. Although electron microscopy is a powerful tool, it has its limitations when used to examine the mode of action of biocides. Indeed, there was no evidence of gross structural alteration to Acanthamoeba castellani or Aspergillus fumigatus following treatment.     

Half-conductive coupling interconnection technology for digitaltransmission between CMOS chips

This paper describes how to use half-conductive coupling (HC-coupling) to obtain digital interconnections between two flip-chip standard CMOS integrated circuits. For process simplicity, the HC-layer can be unpatterned and the CMOS chips do not require any post-processing steps. Measurements of a complete HC-coupling, digital communication link show reliable operation up to 100 Mb/s channel speed. The two flipped prototype CMOS chips were fabricated in 0.8-μm, 5-V CMOS. The I/O pads' pitch was 150 μm     

Expression and effect of resistin on bovine and rat granulosa cell steroidogenesis and proliferation

Resistin, initially identified in adipose tissue and macrophages, was implicated in insulin resistance. Recently, its mRNA was found in hypothalamo-pituitary axis and rat testis, leading us to hypothesize that resistin may be expressed in ovary. In this study, we determined in rats and cows 1) the characterization of resistin in ovary by RT-PCR, immunoblotting, and immunohistochemistry and 2) the effects of recombinant resistin (10, 100, 333, and 667 ng/ml) ± IGF1 (76 ng/ml) on steroidogenesis, proliferation, and signaling pathways of granulosa cells (GC) measured by enzyme immunoassay, [(3)H]thymidine incorporation, and immunoblotting respectively. We observed that resistin mRNA and protein were present in several bovine and rat ovarian cells. Nevertheless, only bovine GC abundantly expressed resistin mRNA and protein. Resistin treatment decreased basal but not IGF1-induced progesterone (P<0.05; whatever the dose) and estradiol (P<0.005; for 10 and 333 ng/ml) production by bovine GC. In rats, resistin (10 ng/ml) increased basal and IGF1-induced progesterone secretion (P<0.0001), without effect on estradiol release. We found no effect of resistin on rat GC proliferation. Conversely, in cows, resistin increased basal proliferation (P<0.0001; for 100-667 ng/ml) and decreased IGF1-induced proliferation of GC (P<0.0001; for 10-333 ng/ml) associated with a decrease in cyclin D2 protein level (P<0.0001). Finally, resistin stimulated AKT and p38-MAPK phosphorylation in both species, ERK1/2-MAPK phosphorylation in rats and had the opposite effect on the AMPK pathway (P<0.05). In conclusion, our results show that resistin is expressed in rat and bovine ovaries. Furthermore, it can modulate GC functions in basal state or in response to IGF1 in vitro.     

La recherche de granulats en region centre

This study was made on the reaction between aggregate and cement paste in autoclaved concrete and its influence on compressive strength. The specimens mixed with cement and various crushed minerals (149–74 μm) were autoclaved at 181°C for 1–168 hours. Quartz and feldspars (microcline, albite and anorthite) reacted to cement paste, whereas hornblende, augite and olivine did not react. The reaction rate of minerals were, in order, anorthite > quartz > microcline=albite. 11A tobermorite was formed by the reaction between cement paste and quartz, and feldspars. Hydrogarnet was also formed by the reaction between cement paste and anorthite. The compressive strength of the specimens containing quartz and feldspars increased as the curing time was prolonged.     

Efficacy and mechanisms of action of sodium hypochlorite on Pseudomonas aeruginosa PAO1 phage F116

The Pseudomonas aeruginosa PAO1 phage F116 was used to investigate the viricidal activity and the mechanism of action of sodium hypochlorite. The bacteriophage was inactivated with a low concentration (0.0005% available chlorine) of the biocide prepared in tap water but it was less sensitive to a sodium hypochlorite solution prepared in ultra-pure water (0.0075% available chlorine). For all the effective concentrations of sodium hypochlorite (i.e. producing at least 4 log reduction in phage titre), F116 was readily inactivated within 30 s. Electron microscopical investigations of the phage particles challenged with sodium hypochlorite showed a wide variety of deleterious effects, some of which have not been previously observed with other biocides. The wide range of structural alterations observed suggested that sodium hypochlorite has multiple target sites against F116 bacteriophage. A 30 s exposure to sodium hypochlorite (0.001% available chlorine) produced severe damage, the number and severity of which increased with a higher concentration (0.0075% available chlorine) and with a longer contact time. These observations suggested that sodium hypochlorite inactivated F116 bacteriophage by causing structural alterations to the phage head, tail and overall structure, hence possibly releasing the viral genome from damaged capsids in the surrounding media.     

Electron spin resonance spectroscopy: a promising method for studying lipid oxidation in foods

Oxidative reactions that involve lipids are among the most important causes of deterioration of foods and affect both their shelf life and their organoleptic and nutritional properties. Radicals are intermediate key‐constituents in these reactions. Their detection is therefore essential in order to understand and predict early stages of these destructive oxidations. Several Electron Spin Resonance (ESR) methodologies (direct and indirect) make it possible to identify, quantify and measure the reactivity of radical species formed during oxidative‐reductive reactions. They are also used to evaluate the antiradical activity of antioxidants delaying lipid oxidation. An overview on the use of different ESR methodologies to study lipid oxidation in foods is reported in this paper.     

Influence of the support structure on the activity,stability, and metal leaching of a polymer‐supported organotin chloride catalyst

Polymer‐supported organotin chlorides have been synthesized by suspension copolymerization of organotin‐functionalized styrenic monomers using a precipitating porogen. Their activities as reducing catalysts have been evaluated in the reduction of bromoadamantane by sodium borohydride. The influence of the length of the spacer arm between the tin atom and the polymer backbone on the activity and the tin leaching of the supported catalyst have been studied. The nature of the alkyl groups (butyl or phenyl) attached on the tin atom plays an important role on the stability toward successive reuse of the supported catalyst. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1297–1308, 2001     

Mechanical properties of thin glassy polymer films filled with spherical polymer-grafted nanoparticles

It is commonly accepted that the addition of spherical nanoparticles (NPs) cannot simultaneously improve the elastic modulus, the yield stress, and the ductility of an amorphous glassy polymer matrix. In contrast to this conventional wisdom, we show that ductility can be substantially increased, while maintaining gains in the elastic modulus and yield stress, in glassy nanocomposite films composed of spherical silica NPs grafted with polystyrene (PS) chains in a PS matrix. The key to these improvements are (i) uniform NP spatial dispersion and (ii) strong interfacial binding between NPs and the matrix, by making the grafted chains sufficiently long relative to the matrix. Strikingly, the optimal conditions for the mechanical reinforcement of the same nanocomposite material in the melt state is completely different, requiring the presence of spatially extended NP clusters. Evidently, NP spatial dispersions that optimize material properties are crucially sensitive to the state (melt versus glass) of the polymeric material.