Analysis of photocurrents at the semiconductor—eletrolyte junction

The photocurrent vs potential characateristics for three different electrolyte—semiconductor junctions, representative of those generally found in semiconductor photoelectrochemistry, are analyzed in detail using parameters which define both the semiconductor and the electrolyte. It is shown that, in general, the behaviour of junctions including semiconductors with sufficiently wide energy pags and large free carriers densities, may be accurately described using the Gärtner model in the potential region which does not include the onset of the photocurrent. In this case, it is the characteristics of the semiconductor which control the photoresponse and the electrolyte does not induce limiting steps in the charge transfer across the interface. If certain restrictive conditions are fulfilled concerning the relative orders of magnitude of the semiconductor space charge region, diffusion length of minority carriers and penetration depth of light into the semiconductor, the value of the flat band potential may be easily determined by ploting i²_phvs V and extrapolating to i²_ph = 0. In the other cases, the relation established by Gärtner between i_ph and V has been verified provided that the free carriers density be sufficiently large.     

Generalized congenital fibromatosis (author's transl)

About a spontaneously regressive case of osteo-cutaneous congenital fibromatosis, the authors describe the characteristics of the disease (32 observations). Although the majority of cases are sporadic, 3 familial observations are in favour of a dominant autosomal transmission of low penetrance. Study of the familial cases and analysis of the different localisations demonstrate the unicity of the so-called diffuse forms with visceral involvement and of the so-called generalized forms without visceral involvement congenital fibromatosis is characterized by several fibromas at birth: in two-thirds of the cases, it is a purely cutaneous or osteocutaneous form, which disappears spontaneously; in one third of the cases, it is a cutaneous or osteo-cutaneous form with lethal visceral involvement.     

A practical approach for robust control of flexible structures

This paper deals with the robust control of linear single-input, single-output (SISO) systems. First, general concepts of the frequency-domain approach are presented. We then focus on the particular problem of flexible structure and control. A new method is proposed which combines the advantages of hyperstability and small gain approaches. Finally, an application of an industrial sight system prototype is detailed.     

Electronic transfer through Langmuir-Blodgett layers of capped platinum nanoparticles: An electrochemical approach

Amine functionalized platinum nanoparticles have been modified by over-grafting two different molecules, 2-thiophenecarbonyl chloride (Pt-1) and 1-hexyl-4-(4-isothiocyanatophenyl)-bicyclo (2, 2, 2) octane (Pt-2). Cyclic voltammetry was performed at gold electrodes coated with Langmuir-Blodgett (LB) mixed films of Pt-1 and Pt-2 nanoparticles, and behenic acid. From five layers the electrochemical response was essentially provided by the last LB component. The electrochemical responses towards the [Fe(CN)₆]^3−/4− couple were strongly influenced by the nature of the over-grafted molecules: films of Pt-2 presented an almost complete blocking effect, while films of Pt-1 allowed the redox reaction to occur on Pt nanoparticles. In order to understand the reasons for such different behaviors we built up hetero-nanostructures by superposing Pt-1 and Pt-2 LB layers in different ways, yielding different kinds of “sandwich” structures. The electrochemical response depended on the electrode ending. When Pt-1 nanoparticles were in the outer layer, in contact with the electrolyte solution, the electrode was electroactive toward the redox probe, while when Pt-2 layers were in the outer layer no electroactivity was detected. For sandwiches made of Pt-1, with a variable thickness of an intercalated film of Pt-2, the electrode response to [Fe(CN)₆]^3−/4− was modulated by the thickness of the inter-layer: the thicker the layer, the lower the response.     

DUV-induced micro and nanopatterning of polymer plasma deposited films

A simple method is described for patterning polymer surfaces with reactive groups. This entails pulsed plasma deposition of anhydride functionalized films, followed by DUV irradiation using a ArF excimer laser. Micro and nano-scale patterning was demonstrated, leading to well defined structures with controlled chemistry and/or geometries. We investigated the chemical changes induced by DUV irradiation. Among other parameters, we demonstrated that the covalent attachment of an amine terminated nucleophile via the aminolysis improved significantly the DUV photosensitivity. Using this approach it was possible to create combinatorial patterned surfaces. In particular such patterned polymer films appear as excellent candidate to study the effect of nanostructuration on the development of biofilms.     

On the reduction of thermal and flicker noise in ENG signal recording amplifiers

Because of the extremely low amplitude of the input signal, the design of electro-neuro-graph (ENG) amplifiers involves a special care for flicker and thermal noise reduction. The task becomes really challenging in the case of implantable electronics, because power consumption is restricted to few hundreds μW. In this work, two different circuit techniques aimed to reduce flicker and thermal noise, in ultra-low noise amplifiers for implantable medical devices, are demonstrated. The circuit design, and measurement results are presented, in both cases showing an excellent performance, and noise to power consumption trade-off. In the first circuit, a very simple low-pass G_m–C chopper amplifier is used for flicker noise cancellation. It consumes only 28 mW, with a measured input referred noise and offset of 2  $ {{{\text{nV}}} \mathord{\left/ {\vphantom {{{\text{nV}}} {\sqrt {{\text{Hz}}} }}} \right. \kern-0em} {\sqrt {{\text{Hz}}} }} $ , and 2.5 μV, respectively. In the second circuit, a ultra-low noise amplifier, a energy-efficient DC–DC down-converter, and low voltage design techniques are combined, for the reduction of thermal noise with a minimum power consumption. Measured input referred noise in this case was 5.5  $ {{{\text{nV}}} \mathord{\left/ {\vphantom {{{\text{nV}}} {\sqrt {{\text{Hz}}} }}} \right. \kern-0em} {\sqrt {{\text{Hz}}} }} $ at only 380 μW power consumption. Both circuits were fabricated in a 1.5 μm technology.     

How Mixing and Light Heterogeneity Impact the Overall Growth Rate in Photobioreactors

The microalgae growth rate in photobioreactors responds with inertia to light stimuli. Here, light variations experienced by the algae are accessed through a coupling of an irradiance field calculation and a Lagrangian particle tracking. The response of algae to fluctuating light is then described by a relaxation model involving a single time constant, the value of which is identified from published data. The overall growth rate is calculated as the sum of individual growth rates of all particles. Instantaneous adaptation and full integration asymptotic behaviors are recovered whilst a finite time constant reveals that the overall growth rate is dependent both on mixing and light distribution. This methodology thus quantitatively relates the design parameters to the photobioreactor performance.     

Lamin-Related Congenital Muscular Dystrophy Alters Mechanical Signaling and Skeletal Muscle Growth

Laminopathies are a clinically heterogeneous group of disorders caused by mutations in the LMNA gene, which encodes the nuclear envelope proteins lamins A and C. The most frequent diseases associated with LMNA mutations are characterized by skeletal and cardiac involvement, and include autosomal dominant Emery–Dreifuss muscular dystrophy (EDMD), limb-girdle muscular dystrophy type 1B, and LMNA-related congenital muscular dystrophy (LMNA-CMD). Although the exact pathophysiological mechanisms responsible for LMNA-CMD are not yet understood, severe contracture and muscle atrophy suggest that mutations may impair skeletal muscle growth. Using human muscle stem cells (MuSCs) carrying LMNA-CMD mutations, we observe impaired myogenic fusion with disorganized cadherin/β catenin adhesion complexes. We show that skeletal muscle from Lmna-CMD mice is unable to hypertrophy in response to functional overload, due to defective fusion of activated MuSCs, defective protein synthesis and defective remodeling of the neuromuscular junction. Moreover, stretched myotubes and overloaded muscle fibers with LMNA-CMD mutations display aberrant mechanical regulation of the yes-associated protein (YAP). We also observe defects in MuSC activation and YAP signaling in muscle biopsies from LMNA-CMD patients. These phenotypes are not recapitulated in closely related but less severe EDMD models. In conclusion, combining studies in vitro, in vivo, and patient samples, we find that LMNA-CMD mutations interfere with mechanosignaling pathways in skeletal muscle, implicating A-type lamins in the regulation of skeletal muscle growth.