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The wavelength used during photochemical grafting of alkene onto silicon related surfaces influences molecular surface coverage. Ultraviolet light leads to apparent highly dense layers on UV absorbing materials due to the side reaction between alkenes resulting in strongly physisorbed dimers whereas higher wavelengths lead to dense and well-controlled layers. [ABSTRACT FROM AUTHOR]

The optimization of functional optical devices requires the appropriate control of light propagation, which can be achieved by using engineered dielectric structures. Innovative materials combination and fabrication strategies are required to achieve a robust gain in performance without impacting manufacturing complexity and cost. In the present work, a novel liquid‐based approach is proposed for the simple and scalable fabrication of highly efficient and robust optical multilayer dielectric coatings. In particular, a sol–gel process is developed that enables the fabrication of large‐area distributed Bragg reflectors (DBR) integrating macroporous materials of controlled closed porosity. The DBRs have a very high index contrast, excellent and tunable optical properties, and high stability of performance and structural integrity with respect to crack formation and delamination, even against harsh ageing tests or solvent exposure. The potential of this approach to be integrated within existing optoelectronic architectures is demonstrated through the integration of a DBR structure as a back reflector in an amorphous silicon solar cell (a‐Si:H), resulting in a significant increase in light absorption, photocurrent, and overall efficiency. This opens the way towards simple dielectric engineering of robust photoactive devices based on the versatile use of liquid routes for the deposition of structured dielectric coatings. [ABSTRACT FROM AUTHOR]

Depth profiling of positron annihilation characteristics has been used to investigate the pore size distribution in macroporous PMMA latex-templated SiO2 films deposited on glass or Si and prepared with 11-70% porosity. The correlation between the annihilation characteristics shows that ortho-positronium (o-Ps) escape (re-emission) into vacuum occurs in all films with a porosity threshold that is pore size dependent. For 60±2% porosity, the o-Ps re-emission yield decreases from ∼0.25 to ∼0.11 as the pore size increases from 32 to 75 nm. The o-Ps re-emission yield is shown to vary linearly with the specific surface area per mass unit and the slope is independent of pore size, 9.1±0.4 g cm-2. For 32 nm pores, the o-Ps annihilation lifetimes in the films, 17(2) ns and 106(5) ns, show that o-Ps annihilates from micropores with small effective size (1.4±4 nm) and from macropores with large effective size (∼32 nm). Above the porosity threshold, the o-Ps-escape model predicts the annihilation lifetime in the films to be 19±2 ns. Our results imply that o-Ps efficiently detects the microporosity present in the silica walls. At low porosity, its capture into the micropores competes with its capture into the macropores. At higher porosity (when the distance between micropores and macropores becomes small), this capture into the micropores assists the capture into the macropores. [ABSTRACT FROM AUTHOR]

Laser induced forward transfer (LIFT) is a direct printing technique. Because of its high application potential, interest continues to increase. LIFT is routinely used in printing, spray generation and thermal-spike sputtering. Biological material such as cells and proteins have already been transferred successfully for the creation of biological microarrays. Recently, modeling has been used to explain parts of the ejection transfer process. No global modeling strategy is currently available. In this paper, a hydrodynamic code is utilized to model the jet formation process and estimate the constraints obeyed by the bioelements during the transfer. A self-consistent model that includes laser energy absorption, plasma formation via ablation, and hydrodynamic processes is proposed and confirmed with experimental results. Fundamental physical mechanisms via one-dimensional modeling are presented. Two-dimensional (2D) simplified solutions of the jet formation model equations are proposed. Predicted results of the model are jet existence and its velocity. The 2D simulation results are in good agreement with a simple model presented by a previous investigator. [ABSTRACT FROM AUTHOR]

The interactions between femtosecond laser and collagen films have been investigated. Collagen was obtained in our laboratory from tail tendons of young albino rats. Thin collagen films were obtained by casting of collagen solution onto glass plates. The changes on film surfaces after femtosecond laser irradiation were examined using scanning electron microscopy. The laser irradiation caused an expansion of materials above the surface of collagen films. The obtained results are considered in terms of possible ablation mechanisms and compared with recent results obtained with nanosecond laser pulses. [ABSTRACT FROM AUTHOR]

In the present paper, specific interest has been devoted to the design of new hybrid materials associating Ti–6Al–4V alloy and osteoprogenitor cells through the grafting of two RGD containing peptides displaying a different conformation (linear RGD and cyclo-DfKRG) onto titanium surface. Biomimetic modification was performed by means of a three-step reaction procedure: silanization with APTES, cross-linking with SMP and finally immobilization of peptides thanks to thiol bonding. The whole process was performed in anhydrous conditions to ensure homogeneous biomolecules layout as well as to guarantee a sufficient amount of biomolecules grafted onto surfaces.The efficiency of this new route for biomimetic modification of titanium surface was demonstrated by measuring the adhesion between 1 and 24 h of osteoprogenitor cells isolated from HBMSC. Benefits of the as-proposed method were related to the high concentration of peptides grafted onto the surface (around 20 pmol/mm2) as well as to the capacity of cyclo-DfKRG peptide to interact with integrin receptors. Moreover, High Resolution β-imager (using [35S]-Cys) has exhibited the stability of peptides grafted onto the surface when treated in harsh conditions. [Copyright &y& Elsevier]

Because of the Ti3+ defects responsibility for dissociative adsorption of water onto TiO2 surfaces and due to the hydroxyls influence on the biological behavior of titanium, controlling the Ti3+ surface defects density by means of low-temperature vacuum annealing is proposed to improve the bone/implant interactions. Experiments have been carried out on Ti-6Al-4V alloys exhibiting a porous surface generated primarily by chemical treatment. XPS investigations have shown that low-temperature vacuum annealing can create a controlled number of Ti3+ defects (up to 21% Ti3+/Ti4+ at 573 K). High Ti3+ defect concentration is linked to surface porosity. Such surfaces, exhibiting high hydrophilicity and microporosity, would confer to titanium biomaterials a great ability to interact with surrounding proteins and cells and hence would favor the bone anchorage of as-treated implants. [Copyright &y& Elsevier]

A limited number of genes, including the human brain-derived neutrotrophic factor (BDNF) gene, have been identified in the human chromosome 11p14 region. Since this area is involved in a genetic disorder (WAGR syndrome) and because of interest in studying the regulation of the human BDNF gene, we have established a detailed transcript map of a 810-kb region clone in a yeast artificial chromosome (YAC), corresponding to a portion of this genomic locus. A set of nested deletion mutants has been generated to map genes at a mean resolution of 75 kb. Four genic markers from available mapping databases have been mapped on the YAC. Ten potential novel human exons have been isolated by a 3' terminal exon trapping procedure directly applied to purified YAC DNA. Most of these exons display polyadenylation signals and they all yield positive signals in RT-PCR experiments, confirming their status of transcribed sequences. The BDNF gene is now co-localised with three other genes on a 120 kb DNA fragment. [ABSTRACT FROM AUTHOR]

We compared the rectal microflora of 16 patients with surgically excluded colorectum with 16 healthy controls. The cause of diversion was inflammatory bowel disease (n = 10), colon cancer (n = 3), miscellaneous (n = 3). Six patients had a diversion colitis. In the excluded colorectum, the total bacterial count was only slightly lower than controls but the variety of the flora was significantly reduced. This reduction was confined to strict anaerobes, mainly the genus Eubacterium and Bifidobacterium. Among aerobes, enterobacteria were more often isolated than in controls. This altered microflora of excluded colorectum could be involved in the mucosal damage observed in some cases. [ABSTRACT FROM PUBLISHER]

Our aim was to study the jejunal motility (a) in seven patients receiving longterm (median: 24 days) cyclic total parenteral nutrition (CTPN) for an acute exacerbation of Crohn's disease involving the ileum and/or the colon without any sign of occlusion and (b) in six healthy volunteers undergoing the same parenteral nutrition for one day after an overnight fast. Continuous recordings, lasting 20 hours, were carried out in patients after correction of their nutritional status and significant improvement of the Crohn's disease activity index. In five of the seven patients, we recorded seven to 14 phase III episodes (PIII) (median: 10), both more frequent and slower during the nocturnal part of the recording time as compared with diurnal. Seven to 18 PIIIs (median: 12) were found in controls. The overall duration of the motor activity was not different between these five patients and controls. In the remaining two patients, no PIII episode was recorded and 79% and 57% respectively of the whole recording time consisted of irregular motor activity. Our work therefore, shows that: (a) PIIIs remain and have a circadian variation in their periodicity and propagation velocity, in most of our patients undergoing longterm CTPN (b) CTPN does not determine a longer duration of motor rest of the small bowel in patients than in controls submitted for a short period of time to the same parenteral intake. [ABSTRACT FROM PUBLISHER]

A pathogenic role of nitric oxide has been suggested in acute and chronic intestinal inflammation. We took the opportunity offered by studies in patients with excluded colon, which represents a model of chronic intestinal inflammation with no exogenous nitrite or nitrate supply, to evaluate the quantity and the quality of nitrate reducers in diversion colitis. Thirty patients (17 men, 13 women, mean age 45 years) having an excluded colon for various reasons were sampled by rectal swabs and compared to 30 healthy controls (11 men, 19 women, mean age 28 years). The percentage of nitrate-reducers among the total count of subcultured bacteria was 46 +/- 41% (mean +/- SD) in patients with diversion colitis as compared to 19 +/- 24% in healthy controls. This difference was significant (P < 0.05) despite great heterogeneity in individual values. In patients with diversion colitis, 75/254 (29.5%) different isolated bacterial strains were nitrate-reducers as compared to 61/294 (21%) (P < 0.05) in controls. Among the 75 nitrate-reducing strains isolated from patients with diversion colitis, 55 were aerobes. Pseudomonas species were only encountered in this population. The predominant group was enterobacteria with a high isolation rate of species belonging to the genera Proteus, Providencia, and Morganella. In healthy controls nitrate-reducing anaerobes were nearly as frequent as aerobes. The most frequent species was Eubacterium lentum, followed by Clostridium perfringens. It could be suggested that nitric oxide synthase might produce a bacterial substrate increasing the growth of bacteria with a high pathogenic potential, creating conditions for chronic inflammation and infection in patients with excluded colon. [ABSTRACT FROM AUTHOR]

The aim of this study was to describe the motor patterns found in two patients with recurrent cholangitis episodes after Roux-en-Y hepaticojejurtostomy. In one patient, cholangitis was due to a stenosis of the anastomosis between the limb and the left intrahepatic bile duct, while motility of the limb, duodenum, and distal jejunum was normal. In the second patient, no anatomical explanation was found for cholangitis attacks. However, although the duodenal motor activity was normal, the motility of the limb and of the jejunum below the jejunojejunal anastomosis was grossly abnormal: permanent minute rhythm, phase Ills absent or rare and slowly propagated, all motor abnormalities that could promote bacterial overgrowth in the limb. This stresses the interest in performing motor studies of the Rouxlimb when cholangitis remains unexplained after Roux-en-Y hepaticojejunostomy. [ABSTRACT FROM AUTHOR]

Ultrasonics signals at frequencies 5.7±0.1 and 6.8±0.1 GHz are measured in two organelles of a single vegetal cell in vitro with a picosecond ultrasonic technique. Using standard values for cell optical index, ultrasound velocities of 1.6±0.1 and 2.0±0.1 μm/ns are measured from several signals recorded in the vacuole and in the nucleus of a single Allium cepa cell, respectively. A 1 μm lateral and 0.25 μm depth resolution is attained. [ABSTRACT FROM AUTHOR]

Neurogenin 2 (Ngn2) is a proneural gene involved in neuronal differentiation and subtype specification in various regions of the nervous system. In the ventral midbrain, Ngn2 is expressed in a spatiotemporal pattern that correlates with the generation of mesencephalic dopaminergic (mesDA) neurons. We show here that lack of Ngn2 impairs the development of mesDA neurons, such that less than half of the normal mesDA neuron number remain in Ngn2 mutant mice at postnatal stages. Analysis of Ngn2 mutant mice during mesDA neurogenesis show that medially located precursors are formed but are arrested in their differentiation at a stage when they have not yet acquired the characteristics of mesDA neuron precursors. Loss of Ngn2 function appears to specifically affect the generation of DA neurons, as the development of other types of neurons within the ventral midbrain is unaltered. Ngn2 is the first example of a gene expressed in progenitors in the ventricular zone of the mesDA neuron domain that is essential for proper mesDA neuron differentiation, and whose loss of function causes impaired mesDA neurogenesis without other major abnormalities in the ventral midbrain. [ABSTRACT FROM AUTHOR]

Abstract: The authors consider liaison psychiatry through the concept of binding in psychopathology. They study the notions of projective identification, pulsional dualism and counter transference analysis. This leads them to describe a three-parts psychic apparatus representation and to distinguish hysteria from hypochondria to which the syndrom of Münchausen by procur is related. Negative but also positive aspects of counter transference are evoked. [Copyright &y& Elsevier]

Abstract: Nervous system formation integrates control of cellular proliferation and differentiation and is mediated by multipotent neural progenitor cells that become progressively restricted in their developmental potential before they give rise to differentiated neurons and glial cells. Evidence from different experimental systems suggests that Geminin is a candidate molecule linking proliferation and differentiation during nervous system development. We show here that Geminin and its binding partner Cdt1 are expressed abundantly by neural progenitor cells during early mouse neurogenesis. Their expression levels decline at late developmental stages and become undetectable upon differentiation. Geminin and Cdt1 expressing cells also express Sox2 while no overlap is detected with cells expressing markers of a differentiated neuronal phenotype. A fraction of radial glial cells expressing RC2 and Pax6 are also immunoreactive for Geminin and Cdt1. The majority of the Geminin and Cdt1 expressing cell populations appears to be distinct from fate-restricted precursor cells expressing Mash1 or Neurogenin2. Bromo-deoxy-uridine (BrdU) incorporation experiments reveal a cell cycle specific expression in neural progenitor cells, with Geminin being present from S to M phase, while Cdt1 expression characterizes progenitor cells in G1 phase. Furthermore, in vitro differentiation of adult neurosphere cultures shows downregulation of Geminin/Cdt1 in the differentiated state, in line with our data showing that Geminin is present in neural progenitor cells of the CNS during mouse embryogenesis and adulthood and becomes downregulated upon cell fate specification and differentiation. This suggests a role for Geminin in the formation and maintenance of the neural progenitor cells. [Copyright &y& Elsevier]

The Vanguad™ endoprotheses were implanted transluminally through the femoral route and deployed at the site of surgically created aneurysms in the thoracic or abdominal aortas of dogs for prescheduled periods of implantation of 1 week, 1, 2 and 3 months. The in vivo dimensional stability of the endoprothesis was confirmed by angiography after insertion and before the sacrifice and by macroscopic observations after retrieval. Histological and scanning electron microscopic (SEM) studies were performed to assess the healing sequence of the device. Microscopic studies of the textile components and surface chemical analysis of the Nitinol wires by electron spectroscopy for chemical analysis (ESCA) were undertaken, after specimen cleaning to remove adherent tissue, to detect structural modifications to the textile structure and to evaluate the bioresilience of the Nitinol. Analysis of the angiograms after implantation and before the sacrifice revealed that morphological changes such as sliding and compression of the metal structure occurred initially after deployment and during implantation. Thrombogenicity of the luminal surface of the endoprotheses was low but the healing was still incomplete after 90 days of implantation. The lack of stability of the metal structure may explain the migration distally and the poor healing of the device. ESCA analysis showed that a physiosorbed passivation layer covered the surface of the Nitinol wires masking the nickel (Ni) component of the alloy. Ion bombardments of the surface of the wires confirmed the presence of a contaminated layer composed of carbon and other elements followed by a highly oxidized titanium (Ti) layer, and then, by the Ti/Ni alloy. Although innovative, the minimally-invasive endovascular technique for the treatment of aortic aneurysms is still in its infancy. Significant improvements are required in terms of ease of handling, effectiveness, innocuousness, biostability and healing. [Copyright &y& Elsevier]