Reversible Light‐Triggered Control of Emulsion Type and Stability

Khoukh, Sihame; Perrin, Patrick; Berc, Florian Bes de; Tribet, Christophe

doi:10.1002/cphc.200500240

Cited by 33 publications

(42 citation statements)

References 24 publications

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“…It is well known that the orientation or phase behavior of light sensitive molecules (surfactants or surface active moieties) or nano-particles at interfaces can be altered by using light [35,36]. As nitrate acts as a primary chromophore, which in the presence of organic moieties produces nitrite [31].…”

Section: Rheological Characteristics Of the Catalyst Support Precursomentioning

confidence: 99%

Co-Assembled Supported Catalysts: Synthesis of Nano-Structured Supported Catalysts with Hierarchic Pores through Combined Flow and Radiation Induced Co-Assembled Nano-Reactors

Akay

2016

Catalysts

106

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Abstract:A novel generic method of silica supported catalyst system generation from a fluid state is presented. The technique is based on the combined flow and radiation (such as microwave, thermal or UV) induced co-assembly of the support and catalyst precursors forming nano-reactors, followed by catalyst precursor decomposition. The transformation from the precursor to supported catalyst oxide state can be controlled from a few seconds to several minutes. The resulting nano-structured micro-porous silica supported catalyst system has a surface area approaching 300 m 2 /g and X-ray Diffraction (XRD)-based catalyst size controlled in the range of 1-10 nm in which the catalyst structure appears as lamellar sheets sandwiched between the catalyst support. These catalyst characteristics are dependent primarily on the processing history as well as the catalyst (Fe, Co and Ni studied) when the catalyst/support molar ratio is typically 0.1-2. In addition, Ca, Mn and Cu were used as co-catalysts with Fe and Co in the evaluation of the mechanism of catalyst generation. Based on extensive XRD, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) studies, the micro-and nano-structure of the catalyst system were evaluated. It was found that the catalyst and silica support form extensive 0.6-2 nm thick lamellar sheets of 10-100 nm planar dimensions. In these lamellae, the alternate silica support and catalyst layer appear in the form of a bar-code structure. When these lamellae structures pack, they form the walls of a micro-porous catalyst system which typically has a density of 0.2 g/cm 3 . A tentative mechanism of catalyst nano-structure formation is provided based on the rheology and fluid mechanics of the catalyst/support precursor fluid as well as co-assembly nano-reactor formation during processing. In order to achieve these structures and characteristics, catalyst support must be in the form of silane coated silica nano-particles dispersed in water which also contains the catalyst precursor nitrate salt. This support-catalyst precursor fluid must have a sufficiently low viscosity but high elastic modulus (high extensional viscosity) to form films and bubbles when exposed to processing energy sources such as microwave, thermal, ultra-sound or UV-radiation or their combination. The micro-to-nano structures of the catalyst system are essentially formed at an early stage of energy input. It is shown that the primary particles of silica are transformed to a proto-silica particle state and form lamellar structures with the catalyst precursor. While the nano-structure is forming, water is evaporated leaving a highly porous solid support-catalyst precursor which then undergoes decomposition to form a silica-catalyst oxide system. The final catalyst system is obtained after catalyst oxide reduction. Although the XRD-based catalyst size changes slightly during the subsequent heat treatments, the nano-structure of the catalyst system remains substantially unaltered as evaluated through TEM images. Howev...

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Section: Rheological Characteristics Of the Catalyst Support Precursomentioning

confidence: 99%

Co-Assembled Supported Catalysts: Synthesis of Nano-Structured Supported Catalysts with Hierarchic Pores through Combined Flow and Radiation Induced Co-Assembled Nano-Reactors

Akay

2016

Catalysts

106

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“…Stimuli‐responsive emulsions have become very popular in the recent years,11 and ionic strength, pH,12 light13 or temperature14 have revealed to be efficient triggers to change the emulsion type (W/O or O/W). This can be achieved in particular by using polymers,15 which are able to modify the curvature of the oil‐water interface and promote the phase inversion.…”

mentioning

confidence: 99%

Direct visualization of Smad1/5/8‐mediated transcriptional activity identifies podocytes and collecting ducts as major targets of BMP signalling in healthy and diseased kidneys

Leeuwis

Nguyen

Lopes

et al. 2011

The Journal of Pathology

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Bone morphogenetic protein 7 (BMP7) is a key determinant of renal response to injury, exhibiting strong protective as well as regenerative potential in a variety of experimental models. In vitro, beneficial effects of stimulation with BMP7 and other BMPs have been observed in many renal cell types. Still, it remains poorly understood which cells in the native kidney actually respond to BMPs in health and disease. Here, we report the use of BRE:gfp mice expressing green fluorescent protein (GFP) under the control of a pSmad1/5/8-specific BMP-responsive element (BRE) to directly visualize the spatiotemporal distribution of transcriptional activity downstream of canonical BMP signalling in healthy kidneys and in two distinct models of kidney disease. BRE-GFP signal coincided with expression of endogenous BMP target genes but, surprisingly, it was much more restricted than expected from the widespread distribution of pSmad1/5/8, a classical component of canonical BMP signal tranduction. BRE-GFP was mainly present in podocytes and collecting duct cells, and both glomerular and medullary BRE-GFP decreased following ischaemia-reperfusion injury as well as following unilateral ureteric obstruction, together with decreased BMP7, pSmad1/5/8 and BMP target gene expression. Remarkably, however, BRE-GFP was increased in injured proximal tubules in association with up-regulation of BMP receptors ALK2 and ALK3. Thus, native BMP transcriptional activity is much more restricted than previously suggested based on pSmad1/5/8 detection alone, and its response to injury varies according to cell type and nephron segment.

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“…When incorporated into a self -assembled system, the activation and deactivation of photochromics cause a steric disturbance in the packing in the self -assembled structures resulting in a change in, for example, drug release. In some cases, photoisomerization does not compromise interface integrity, and a pulsatile delivery may be achieved (Khoukh et al, 2005 ;Tong et al, 2005 ;Zhang et al, 2009 ). Research into photochromic self -assembled systems has focused on azobenzene and spiropyran moieties among others (Eastoe and Vesperinas, 2005 ).…”

Section: Lightmentioning

confidence: 99%

“…The main uses of azobenzene are as yellow/orange synthetic dyes; however, molecules and surfactants containing an azobenzene moiety have been used to impart control over membrane permeability in aggregates such as emulsions (Bufe and Wolff, 2009 ;Cicciarelli et al, 2007 ;Han and Hara, 2005 ;Khoukh et al, 2005 ), Langmuir -Blodgett fi lms (Haruta et al, 2008 ;Kumar et al, 2009b ;Oki and Nagasaka, 2009 ;Sorensen et al, 2008 ), liposomes and vesicular membranes Kuiper and Engberts, 2004 ;Kuiper et al, 2008 ;Lei and Hurst, 1999 ;Liu et al, 2005 ;Morgan et al, 1995 ;Song et al, 1995 ;Zou et al, 2008 ), polymeric vesicles (Liu et al, 2008 ;Tong et al, 2005 ), hydrogels (Zhao and Stoddart, 2009 ), silica materials (Tanaka et al, 2007 ), and liquid crystals (Corvazier and Zhao, 1999 ;Yamamoto et al, 2006Yamamoto et al, , 2009Yi et al, 2009 ). The isomerization of the azo -moiety is suffi cient to destabilize the surrounding area and, as a consequence, induce a phase transformation or disruption of the bilayer as schematically demonstrated in panel (b) of Figure 9.5 .…”

Section: Lightmentioning

confidence: 99%