Quantitative mapping of high modulus materials at the nanoscale: comparative study between atomic force microscopy and nanoindentation.

Local mechanical properties of submicron features are of particular interest due to their influence on macroscopic material performance and behaviour. This study is focused on local nanomechanical measurements, based on the latest Atomic Force Microscopy (AFM) mode, where the peak force set point is finely controlled at each pixel. After probe calibration, we evaluate the impact of spring constant of two AFM hand-crafted natural full diamond tips with steel cantilevers, used for mapping. Based on the fast capture of the cantilever deflection at each pixel and real time force curve analysis in the elastic region, AFM local measured contact moduli mappings of the silica beads (>50 GPa) incorporated in an epoxy resin matrix, are compared with those determined using classical instrumented nanoindentation tests. Our analyses show that with the two AFM probes, without local residual deformation, the high moduli of the silica beads measured with this advanced AFM mode are within the standard deviation of the values determined by classical nanoindentation. LAY DESCRIPTION: The knowledge of material properties at the nanometer scale is a key parameter for well understanding and determining the behavior of material at macroscopic scale. In this paper, we compare two methods (an advanced mode and a classical one) based on the analysis of probes in interaction with the surface of studied material. We focus on a latest developed mode for determining local mechanical properties with a very high spatial resolution. For the advanced mode, we also consider two different hand-crafted probes. Our analyses show that with the high spatial resolution advanced mode, local mechanical properties are well determined. We also highlight the impact of the properties of the used probes for this advanced mode. In a final step, the power of the presented investigation lies in the fact that it does not modify the topography of the surface.

Piezoresistance of top-down suspended Si nanowires.

Measurements of the gauge factor of suspended, top-down silicon nanowires are presented. The nanowires are fabricated with a CMOS compatible process and with doping concentrations ranging from 2 × 10(20) down to 5 × 10(17) cm(-3). The extracted gauge factors are compared with results on identical non-suspended nanowires and with state-of-the-art results. An increase of the gauge factor after suspension is demonstrated. For the low doped nanowires a value of 235 is measured. Particular attention was paid throughout the experiments to distinguishing real resistance change due to strain modulation from resistance fluctuations due to charge trapping. Furthermore, a numerical model correlating surface charge density with the gauge factor is presented. Comparison of the simulations with experimental measurements shows the validity of this approach. These results contribute to a deeper understanding of the piezoresistive effect in Si nanowires.

Anti-inflammatory effect by lentiviral-mediated overexpression of IL-10 or IL-1 receptor antagonist in rat glial cells and macrophages.

Neuroinflammation, as defined by activation of local glial cells and production of various inflammatory mediators, is an important feature of many neurological disorders. Expression of pro-inflammatory mediators produced by glial cells in the central nervous system (CNS) is considered to contribute to the neuropathology observed in those diseases. To diminish the production or action of pro-inflammatory mediators, we have used lentiviral (LV) vector-mediated encoding rat interleukin-10 (rIL-10) or rat interleukin-1 receptor antagonist (rIL-1ra) to direct the local, long-term expression of these anti-inflammatory cytokines in the CNS. We have shown that cultured macrophages or astroglia transduced with LV-rIL-10 or LV-rIL-1ra produced far less tumor necrosis factor (TNF)alpha or IL-6, respectively in response to pro-inflammatory stimuli. Moreover, intracerebroventricular (i.c.v.) administration of LV-rIL-10 or LV-rIL-1ra resulted in transduction of glial cells and macrophages and, subsequently reduced TNFalpha, IL-6 and inducible nitric oxide synthase (iNOS) expression in various brain regions induced by inflammatory stimuli, whereas peripheral expression of these mediators remained unaffected. In addition, expression levels of the anti-inflammatory cytokines IL-4 and transforming growth factor-beta were not altered in either brain or pituitary gland. Furthermore, i.c.v. administration of LV-rIL-10 or LV-rIL-1ra given during the remission phase of chronic-relapsing experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis, improved the clinical outcome of the relapse phase. Thus, local application of LV vectors expressing anti-inflammatory cytokines could be of therapeutic interest to counteract pro-inflammatory processes in the brain without interfering with the peripheral production of inflammatory mediators.

Monitoring endurance running performance using cardiac parasympathetic function.

The aims of the present study were to (1) assess relationships between running performance and parasympathetic function both at rest and following exercise, and (2) examine changes in heart rate (HR)-derived indices throughout an 8-week period training program in runners. In 14 moderately trained runners (36 +/- 7 years), resting vagal-related HR variability (HRV) indices were measured daily, while exercise HR and post-exercise HR recovery (HRR) and HRV indices were measured fortnightly. Maximal aerobic speed (MAS) and 10 km running performance were assessed before and after the training intervention. Correlations (r > 0.60, P < 0.01) were observed between changes in vagal-related indices and changes in MAS and 10 km running time. Exercise HR decreased progressively during the training period (P < 0.01). In the 11 subjects who lowered their 10 km running time >0.5% (responders), resting vagal-related indices showed a progressively increasing trend (time effect P = 0.03) and qualitative indications of possibly and likely higher values during week 7 [+7% (90% CI -3.7;17.0)] and week 9 [+10% (90% CI -1.5;23)] compared with pre-training values, respectively. Post-exercise HRV showed similar changes, despite less pronounced between-group differences. HRR showed a relatively early possible decrease at week 3 [-20% (90% CI -42;10)], with only slight reductions near the end of the program. The results illustrate the potential of resting, exercise and post-exercise HR measurements for both assessing and predicting the impact of aerobic training on endurance running performance.

N-Heterocyclic carbene-stabilized gold nanoparticles with tunable sizes.

A simple and straightforward synthesis of N-heterocyclic carbene (NHC)-protected gold nanoparticles is derived from (benz)imidazolium-AuX4 complexes and NaBH4 only. The proposed method allows size tuning, from 3 to 6 nm, by adding (benz)imidazolium bromide. Changing the reducing agent to tBuNH2BH3 shifts the size range to ca. 6-12 nm. A one pot protocol is also reported from AuCl, (benz)imidazolium bromides and NaBH4, thereby providing an even more straightforward way of producing NHC-capped gold nanoparticles. In addition, X-ray photoelectron spectroscopy (XPS) is used to unambiguously evidence, on the nanoparticles, the covalent bond formed between the NHC and the surface gold atoms.

Using topical aromatherapy for the management of fungating wounds in a palliative care unit.

Odour can be one of the most distressing symptoms of fungating wounds. Traditional dressings and creams often have little effect on odour, but the use of essential oils has proved effective in a palliative care setting.

[Neonatal lupus syndrome: Literature review]. / « Lupus néonatal ¼ : revue de la littérature.

Neonatal lupus syndrome is associated with transplacental passage of maternal anti-SSA/Ro and anti-SSB/La antibodies. Children display cutaneous, hematological, liver or cardiac features. Cardiac manifestations include congenital heart block (CHB); endocardial fibroelastosis and dilated cardiomyopathy. The prevalence of CHB in newborns of anti-Ro/SSA positive women with known connective tissue disease is between 1 and 2% and the risk of recurrence is around 19%. Skin and systemic lesions are transient, whereas CHB is definitive and associated with significant morbidity and a mortality of 18%. A pacemaker must be implanted in 2/3 of cases. Myocarditis may be associated or appear secondly. Mothers of children with CHB are usually asymptomatic or display Sjogren's syndrome or undifferentiated connective tissue disease. In anti-Ro/SSA positive pregnant women, fetal echocardiography should be performed at least every 2 weeks from the 16th to 24th week gestation. An electrocardiogram should be performed for all newborn babies. The benefit of fluorinated corticosteroid therapy for CHB detected in utero remains unclear. Maternal use of hydroxychloroquine may be associated with a decreased recurrent CHB risk in a subsequent offspring. A prospective study is actually ongoing to confirm these findings.

Susceptibility of RDM4 lymphoma cells to LAK-mediated lysis is decreased in tumor bearers fed fish oil high fat regimen.

RDM4 lymphoma cells were grown intraperitoneally in genetically compatible AKR mice fed either regular mouse chow, or diet supplemented with either saturated fat (hydrogenated beef tallow = HBT) or unsaturated fat (fish oil = FO). It was observed that the lymphoma cells number was significantly greater in FO-fed hosts and lower in HBT-fed hosts, than in the mice fed regular chow. The tumor bearers diet did not dramatically influence the rate of DNA synthesis of RDM4 cells, as measured by [3H]thymidine uptake in culture, a few hours after harvesting from the peritoneal cavity. It was repeatedly found that FO feeding of the tumor bearers elicited an increased resistance of RDM4 cells to lysis by LAK effectors, as appraised in vitro by 51Cr release test and in vivo by the "Winn assay". Different FO percentage of the diet (16%, 8%, 4%) resulted in comparable reduction of susceptibility of RDM4 cells to lysis by LAK effectors. Lipid analysis showed that RDM4 cells grown in mice fed FO diet or HBT diet differed markedly in their fatty acid composition and that their resistance to lysis by LAK cells correlated with the quantity of oxidizable fatty acids especially of the n-6 type.

Autoreceptor preference of dopamine D2 receptor agonists correlates with preferential coupling to cyclic AMP.

Dopamine autoreceptors control the synaptic release and turnover of dopamine. Some dopamine agonists display a preference for modulation of autoreceptor functions rather than postsynaptic-driven behaviors. However, the nature of this apparent selectivity is still elusive. To investigate this property, we have used an heterologous expression system in which D2S receptors are coupled to both inhibition of cyclic AMP levels and stimulation of inositol triphosphate production. We show that D2-like receptor agonists display distinct potencies on these two second messenger pathways. Moreover, a strong correlation is observed between the potency of agonists to interact with adenylate cyclase and their potency to modulate autoreceptor functions. Such a correlation does not show up with the phospholipase C pathway. This suggests that autoreceptor preference of D2-like receptor agonists may be driven by a preferential interaction with a second messenger system.

Gross energy cost of horizontal treadmill and track running.

The gross energy cost of treadmill and track running is re-investigated from data published in the literature. An average equation, weighted for the number of subjects in each study, was found: VO2 (ml/kg/min) = 2.209 + 3.163 speed (km/h) for 130 subjects (trained and untrained males and females) and 10 treadmill studies. On the track, wind resistance as predicted by Pugh (1970) was added to the treadmill cost of running and yielded the following equation for adults of average weight and height: VO2 = 2.209 + 3.163 speed + 0.000525542 speed. Between 8 and 25 km/h, the following linear equation: VO2 = 3.5 speed (or met = km/h) was very close to the cubic equation. This linear equation for track running is, however different from the treadmill linear equation, particularly for speeds over 15 km/h. This equation is also slightly different from the one published by Pugh (1970) for track running from 7 trained subjects only.

Sub-unit assembly in the biosynthesis of neomycin. The synthesis of 5-O-beta-D-ribofuranosyl and 4-O-beta-D-ribofuranosyl-2,6-dideoxystreptamines.

The preparation of the deoxy- analogues of two pseudodisaccharide fragments of neomycin, 5-O-beta-D-ribofuranosyl-2,6-dideoxy-streptamine and 6-deoxyneamine is described. When added to the growth medium of a deoxystreptamine-idiotroph of Streptomyces rimosus forma paromomycinus only the latter was incorporated into antibiotic, suggesting an obligatory order for the assembly of sub-units. 4-O-beta-D-Ribofuranosyl-2,6-dideoxystreptamine was also prepared. When added to the growth medium of a deoxystreptamine-idiotroph of Streptomyces fradiae it was converted into the 6-deoxyneomycins, apparently after hydrolysis to 2,6-dideoxystreptamine. The structure of the protected derivatives of the ribofuranosyl 2,6-dideoxystreptamines, potentially useful intermediates for the synthesis of novel antibiotics, was shown by using 15C NMR spectroscopy.

A 'Neural Sampling Theory (NST)' of learning and memory mechanisms.

The purpose of the Neural Sampling Theory (NST) is to propose a plausible neurobiological explanation for some general properties of learning and memory (LM) phenomena, based on the parallelism and redundancy of the nervous system organization; on the psychological side, the NST is inspired by the Stimulus Sampling and Encoding Variability theories. The sampling process which is its core, is not purely random; it depends on temporal and intensity factors. The NST may be implemented at different levels of the nervous system: synapse, neuron, assembly of neurons. Moreover, it may be incorporated in other formal models and improve their degree of neural realism. For instance it allows to give a more realistic representation of the connection weight in the connectionist models and of the noisy character of the nervous system.

Traveling waves and chaotic properties in cellular automata.

Traveling wave solutions of cellular automata (CA) with two states and nearest neighbors interaction on one-dimensional (1-D) infinite lattice are computed. Space and time periods and the number of distinct waves have been computed for all representative rules, and each velocity ranging from 2 to 22. This computation shows a difference between spatially extended systems, generating only temporal chaos and those producing as well spatial complexity. In the first case wavelengths are simply related to the velocity of propagation and the dispersivity is an affine function, while in the second case (which coincides with Wolfram class 3), the dispersivity is multiform and its dependence on the velocities is highly random and discontinuous. This property is typical of space-time chaos in CA. (c) 1999 American Institute of Physics.

[Cervical ripening with balloon catheter for scared uterus: a three-year retrospective study]. / Maturation cervicale par sonde à ballonnet sur utérus cicatriciel : étude rétrospective sur trois ans.

OBJECTIVES: To evaluate, for women with scared uterus, the mechanical cervical ripening with balloon catheter. METHODS: We conducted a retrospective study of our practice of ripening for scared uterus from january 2010 to august 2012. Feasibility, Bishop's score, birth modalities and complications for mothers and babies during this ripening were studied. RESULTS: Thirty-nine medical files were analysed. All patients could have mechanical ripening independently of the internal os status (open or not). The cervical ripening with balloon catheter improved Bishop's score before induction of labour, from 3.54 ± 1.23 to 5.38 ± 1.47 (p=0.02). 64.1% of women had a vaginal delivery. Concerning the predictive factors for vaginal delivery, we only found significant influence of a body mass index less than 30kg/m² (p=0.03). We didn't find any maternal or neonatal complications in our population. CONCLUSION: Mechanical ripening for scared uterus seems to be a useful option to improve vaginal delivery without increasing maternal and foetal morbidity. Anyway, these results have to be confirmed by a randomized controlled trial on a specific scared uterus population.