Ordered arrays of Au catalysts by FIB assisted heterogeneous dewetting.

Synthesizing Au0.8Si0.2 nanocatalysts that are homogeneous in size and have controlled position is becoming a challenging and crucial prequisite for the fabrication of ordered semiconductor nanowires. In this study, Au0.8Si0.2 nanocatalysts are synthesized via dewetting of Au layers on Si(111) during thermal annealing in an ultra-high vacuum. In the first part of the paper, the mechanism of homogeneous dewetting is analyzed as a function of the Au-deposited thickness (h Au). We distinguish three different dewetting regimes: (I) for a low thickness ([Formula: see text]), a submonolyer coverage of Au is stabilized and there is no dewetting. (II) For an intermediate thickness ([Formula: see text]), there is both dewetting and Au0.8Si0.2 phase formation. The size and density of the Au0.8Si0.2 clusters are directly related to h Au. When cooling down to room temperature, the clusters decompose and reject the Si at the Au/Si substrate interface. (III) For a large thickness ([Formula: see text]), only dewetting takes place, without forming AuSi clusters. In this regime, the dewetting is kinetically controlled by the self-diffusion of Au (activation energy ∼0.43 eV) without evidence of an Si-alloying effect. As a practical consequence, when relying solely on the homogeneous dewetting of Au/Si(111) to form the Au0.8Si0.2 catalysts (without a supply of Si atoms from vapor), regime II should be used to obtain good size and density control. In the second part of the paper, a process for ordering the catalysts using focused ion beam-(FIB) assisted dewetting (heterogeneous dewetting) is developed. We show that no matter what the FIB milling conditions and the Au nominal thickness are, dewetting is promoted by ion beam irradiation and is accompanied by the formation of Au0.8Si0.2 droplets. The droplets preferentially form on the patterned areas, while in similar annealing conditions, they do not form on the unpatterned areas. This behavior is attributed to the larger Au-Si interdiffusion in the patterned areas, which results from the Si amorphization induced by the FIB. A systematic analysis of the position of the nanodroplets shows their preferential nucleation inside the patterns, while thicker platelets of almost pure Au are observed between the patterns. The evolutions of the size homogeneity and the occupancy rate of the patterns are quantified as a function of the FIB dose and annealing temperature. Nice arrays of perfectly ordered AuSi catalysts are obtained after optimizing the FIB and dewetting conditions.

[DXA imaging: the multifunction Swiss army knife?]. / Imagerie par DXA: le couteau suisse multifonction?

The significant progress on the quality and resolution of the images obtained by "Dual X-ray Absorptiometry" or DXA has permitted on one hand to improve some existing features and on the other to develop new ones, significantly refining the care of our patients in various pathologies. For example, by improving the prediction of fracture risk by indirect analysis of micro- and macro-architecture of the bone, by looking for markers of associated bone diseases (research vertebral fractures or atypical femoral fractures), or by assessing the metabolic status by the measurement of body composition. With the best performing DXA devices we will soon be able, in clinical routine, to determine bone age, to estimate cardiovascular risk (by measuring the calcification of the abdominal aorta) or to predict the progression of joint osteoarthritis and its evolution after surgical management.

Selective growth and ordering of SiGe nanowires for band gap engineering.

Selective growth and self-organization of silicon-germanium (SiGe) nanowires (NWs) on focused ion beam (FIB) patterned Si(111) substrates is reported. In its first step, the process involves the selective synthesis of Au catalysts in SiO2-free areas; its second step involves the preferential nucleation and growth of SiGe NWs on the catalysts. The selective synthesis process is based on a simple, room-temperature reduction of gold salts (Au³âºCl4⁻) in aqueous solution, which provides well-organized Au catalysts. By optimizing the reduction process, we are able to generate a bidimensional regular array of Au catalysts with self-limited sizes positioned in SiO2-free windows opened in a SiO2/Si(111) substrate by FIB patterning. Such Au catalysts subsequently serve as preferential nucleation and growth sites of well-organized NWs. Furthermore, these NWs with tunable position and size exhibit the relevant features and bright luminescence that would find several applications in optoelectronic nanodevices.

[Long-term implication of bariatric surgery: beyond deficiencies]. / Implications à long terme de la chirurgie bariatrique: au-delà des carences.

Bariatric surgery frequently leads to several nutritional deficiencies that are well reported in the literature. However, numerous other aspects of the patients' life are concerned by bariatric interventions, so that the follow-up of these patients after bariatric surgery does not only encompass a mere correction of the well-known nutritional deficiencies. Only a thorough knowledge of all possible consequences of bariatric interventions permits an adequate follow-up of these patients. Overtly addressing all these issues with the patients before performing a bariatric intervention is the best way for them to be prepared for the intervention itself and to understand the need of a life-long follow-up thereafter.

Low dose endoluminal photodynamic therapy improves murine T cell-mediated colitis.

BACKGROUND AND STUDY AIMS: Low dose photodynamic therapy (LDPDT) may modify the mucosal immune response and may thus provide a therapy for Crohn's disease. We evaluated the efficacy and safety of this technique in a murine T cell-mediated colitis model. METHODS: The safety of LDPDT was first tested in BALB/c mice. Naïve T cells were used to induce colitis in mice with severe combined immunodeficiency, which were followed up endoscopically, and a murine endoscopic index of colitis (MEIC) was developed. The efficacy of LDPDT (10 J/cm (2); delta-aminolevulinic acid, 15 mg/kg bodyweight) was then tested on mice with moderate colitis, while a disease control group received no treatment. The MEIC, weight, length, and histology of the colon, cytokine expression indices, number of mucosal CD4 (+) T cells, percentage of apoptotic CD4 (+) T cells, body weight, and systemic side effects were evaluated. RESULTS: LDPDT improved the MEIC ( P = 0.011) and the histological score ( P = 0.025), diminished the expression indices of the proinflammatory cytokines, interleukin-6 ( P = 0.042), interleukin-17 ( P = 0.029), and interferon-gamma ( P = 0.014), decreased the number of mucosal CD4 (+) T cells, and increased the percentage of apoptotic CD4 (+) T cells compared with the disease control group. No local or systemic side effects occurred. CONCLUSION: LDPDT improves murine T cell-mediated colitis, decreases the proinflammatory cytokines interleukin-6, interleukin-17, and interferon-gamma, and decreases the number of CD4 (+) T cells. No adverse events were observed. Therefore, this technique is now being evaluated in patients with inflammatory bowel disease.

[Management of hyperinsulinemic hypoglycemia post-gastric bypass surgery]. / Gestion des hypoglycémies après le bypass gastrique.

Gastric bypass surgery is an effective treatment for morbid obesity, allowing a substantial weight loss together with an improvement of the cardiovascular and metabolic comorbidities, particularly the glucose control. However, after gastric bypassing, an imbalance between sensitivity and insulin secretion may be observed. This disorder gives rise to hyperinsulinemic hypoglycemia (late dumping syndrome) and is characterized by a dizziness that can be disabling. This problem must be distinguished from conditions provoking similar symptoms, as for instance the early dumping syndrome and the food restriction-related hypoglycemia. Since all these conditions need a particular management, their distinction is essential.

[Progress in bronchoscopy: ultrasound guided fine-needle aspiration (EBUS-TBNA)]. / Progrès en bronchoscopie: ponction guidée par ultrasonographie (EBUS-TBNA).

In case of lung cancer, evaluation of the extension disease is mandatory. Mediastinal nodes must also be evaluated: if a controlateral to the tumor node is metastatic (N3), surgery is no more indicated. As specificity of PET-CT scan is not satisfaying (78%), cytology or histology of a suspect node is necessary. Even if PT-CT scan is negative, node micrometastasis are not excluded. To investigate a mediastinal adenopathy, mediastinoscopy or mediastinotomy are gold standard. Cytoponction guided by ultrasonography (EBUS-TBNA) is a new method which has been proved to be efficient and safe, but necessating some expertise and regular practice. It could be a valuable alternative to mediastinoscopy.

[Pneumonology. Ultrasound-guided transbronchial needle aspiration]. / Pneumologie. Cytoponction transbronchique guidée par uttrasonographie (EBUS-tBNA).

After discovering a lung cancer without extrathoracic metastases, the preoperative mediastinal check-up is of great importance to determine the patients operability. The 78% specificity of activity measuring FDG in a PET examination is clearly insufficient to avoid a biopsy of the incriminated lymph nodes. The investigation of a suspected malignant adenopathy justifies a complete examination by mediastinoscopy or-tomy, which are considered gold standards. The transbronchial fine needle aspiration guided by ultrasound (EBUS-TBNA) constitutes the recent evolution of TBNA, method known for 20 years now but underused. Depending on the operators skill, this new procedure needs a learning curve before being able to replace mediastinoscopy.

Effect of Infant Formula Containing a Low Dose of the Probiotic Bifidobacterium lactis CNCM I-3446 on Immune and Gut Functions in C-Section Delivered Babies: A Pilot Study.

BACKGROUND: In the absence of breast-feeding and its immunomodulatory factors, supplementation of starter infant formula (IF) with probiotics is currently used to support immune functions and gut development. AIM: To assess whether immune-related beneficial effects of regular dose (10(7) CFU/g of powder) of the probiotic Bifidobacterium lactis CNCM I-3446 (hereafter named B. lactis) in starter IF supplementation can be maintained with starter IF containing a low dose (10(4) CFU/g of powder) of B. lactis. METHOD: This trial was designed as a pilot, prospective, double-blind, randomized, single-center clinical trial of two parallel groups (n = 77 infants/group) of C-section delivered infants receiving a starter IF containing either low dose or regular dose of the probiotic B. lactis from birth to six months of age. In addition, a reference group of infants breast-fed for a minimum of four months (n = 44 infants), also born by C-section, were included. All groups were then provided follow-up formula without B. lactis up to 12 months of age. Occurrence of diarrhea, immune and gut maturation, responses to vaccinations, and growth were assessed from birth to 12 months. The effect of low-dose B. lactis formula was compared to regular-dose B. lactis formula, considered as reference for IF with probiotics, and both were further compared to breast-feeding as a physiological reference. RESULTS: Data showed that feeding low-dose B. lactis IF provides similar effects as feeding regular-dose B. lactis IF or breast milk. No consistent statistical differences regarding early life protection against gastrointestinal infections, immune and gut maturation, microbiota establishment, and growth were observed between randomized formula-fed groups as well as with the breast-fed reference group. CONCLUSION: This pilot study suggests that supplementing C-section born neonates with low-dose B. lactis-containing starter formula may impact immune as well as gut maturation similarly to regular-dose B. lactis, close to the breast-feeding reference.

Female-biased dispersal in the monogamous mammal Crocidura russula: evidence from field data and microsatellite patterns.

We investigated dispersal patterns in the monogamous Crocidura russula, based both on direct field observations (mark-recapture data) and on genetic analyses (microsatellite loci). Natal dispersal was found to be low. Most juveniles settled within their natal territory or one immediately adjacent. Migration rate was estimated to two individuals per year and per population. The correlation between genetic and geographical distances over a 16 km transect implies that migration occurs over short ranges. Natal dispersal was restricted to first-litter juveniles weaned in early May; this result suggests a direct dependence of dispersal on reproductive opportunities. Natal dispersal was highly female biased, a pattern unusual among mammals. Its association with monogamy provides support for the resource-competition model of dispersal. Our results demonstrate that a state-biased dispersal can be directly inferred from microsatellite genotype distributions, which opens new perspectives for empirical studies in this area.

Effect of calcium-channel blockade on the aldosterone response to sodium depletion and potassium loading in man.

Angiotensin II (Ang II) and potassium (K+) increase aldosterone (Aldo) production in vitro via Ca2+-dependent mechanisms. To determine the effects of Ca2+ antagonism in vivo, we examined the influence of nifedipine on the Aldo response to Na+ depletion and K+ loading in 11 healthy subjects. On the fifth day of a low-Na+/high-K+ diet (10 mmol Na+/100 mmol K+) the subjects were randomly given either nifedipine 30 mg po or placebo, and on the sixth day they received the alternative drug. KCl in 5% glucose was infused on days 5 and 6 from 10:00 to 12:00 AM (0.6 mmol/kg over 2 hours). Dexamethasone was given to suppress adrenal corticotrophic hormone. Plasma renin activity (PRA) and plasma Aldo were determined every 20 minutes. Nifedipine induced a rise in heart rate at 60 minutes but did not change blood pressure. During KCl/glucose infusions, plasma glucose increased significantly, but plasma K+ remained stable. PRA, but not baseline plasma Aldo, was stimulated by nifedipine. KCl provoked a significant and similar Aldo rise (P less than .01) under placebo and nifedipine. Baseline Aldo/PRA ratio was reduced under nifedipine when compared to placebo (P less than .01), whereas during KCl infusions this ratio was similarly elevated under placebo and nifedipine. We conclude that acute inhibition of slow Ca2+ channels does not interfere with K+-induced Aldo secretion in man, suggesting that adaptive mechanisms operate in vivo.

Association of coarctation of the thoracic aorta with fibromuscular dysplasia of the renal arteries: a case report.

The case of a 25-year-old woman with coarctation of the thoracic aorta and combined bilateral fibromuscular dysplasia of the renal arteries is reported. Although marked hemodynamic changes induced by the coarctation were probably pre-existent, hypertension was revealed only during the last month of her first pregnancy and was spontaneously corrected 2 months post partum. Surgical treatment of the thoracic coarctation did not influence blood pressure which remained normal.

[Nyctohemeral blood pressure profiling by automatic measurement in ambulatory hypertensive patients. Treatment with acebutolol]. / Profil tensionnel nycthéméral par mesure automatique chez des hypertendus ambulatoires. Traitement par l'acébutolol.

Variations in night and day blood pressure were evaluated in 11 patients with essential hypertension. The instrument used (Pressurometer II) automatically records blood pressure every 15 minutes for a mean period of 22 hours and ECG tracings continuously. The mean values of arterial pressure and heart rate were significantly higher during day time than at night, revealing a relative "hypotension" and "bradycardia" during sleep. The cardioselective beta-blocker acebutolol induced a significant fall in diurnal and nocturnal blood pressure, thus uniformly lowering the 24-hour profile.

Cytosolic free calcium and intracellular calcium stores are normal in neutrophils from patients with essential hypertension.

Cytosolic free calcium and intracellular calcium stores were measured in neutrophils by trapping intracellularly the fluorescent calcium indicator Quin-2. Ten patients with untreated essential hypertension were compared to 10- age and sex-matched normotensive subjects. Intracellular calcium concentration and calcium stores did not differ in the two groups. No significant relationship was found between blood pressure and the calcium parameters. These results suggest that essential hypertension is not associated with a generalized cellular alteration in calcium handling.

Blood pressure regulation on low and high sodium diets in normotensive members of normotensive or hypertensive families.

In members of hypertensive families a high sodium intake may have a pressor effect. The mechanism mediating the sodium sensitivity is unclear. Blood pressure, exchangeable sodium, plasma levels of norepinephrine, epinephrine, renin and aldosterone, the pressor response to infused norepinephrine or angiotensin II and the urinary excretion of prostaglandin (PG) E2 and F2 alpha were measured after 7 days of low sodium diet (urinary sodium 13 +/- 10 s.d. mmol/24 h) and 7 days of high sodium intake (urinary sodium 268 +/- 97 mmol/24 h) in 10 normotensive men without and 13 men with family history of essential hypertension. After the low sodium phase, blood pressure, heart rate, exchangeable sodium, plasma levels of norepinephrine, epinephrine, renin and aldosterone, pressor doses of norepinephrine or angiotensin II and the urinary excretion of PGE2 or PGF2 alpha did not differ between the two groups. After the high sodium phase, blood pressure increased only in subjects with positive (P less than 0.05) but not in those with negative family history. In the two groups exchangeable sodium increased (P less than 0.05) and plasma levels of NE (-33% versus -32%), renin (-31% versus -27%) or aldosterone (-74% versus -61%) and pressor doses of NE (-55% versus -54%) or ANG II (-72% versus -44%) decreased by a comparable extent. Urinary PGE2 or PGF2 alpha were unchanged. These findings suggest that a high dietary sodium intake exerts a pressor effect in subjects with familial predisposition to essential hypertension. This pressor effect is not explained by an abnormal adaptation of body sodium, sympathetic activity, renin-angiotensin-aldosterone axis, cardiovascular pressor responsiveness and renal prostaglandin excretion to a high sodium diet.

Diffusion induced effects on geometry of Ge nanowires.

We report diffusion induced germanium nanowire growth and its dependence on the Ge evaporation flux. The wires show a growth rate (dL/dt) in agreement with the previously reported models, but detection of anomalies in the grown wires may indicate the prevalence of the direct Ge impinging effect on large diameter wires. Additionally, we demonstrate that change in deposition flux could directly affect the diffusion length of the Ge adatoms on the wire sidewalls. This in turn modifies the geometry of the grown wires by introducing a lateral growth starting from the base of the wire. A detailed understanding of the deposition flux effect on the growth and geometry of wires will result in improved knowledge of physical properties of wires.

Bright photoluminescence from ordered arrays of SiGe nanowires grown on Si(111).

We report on the optical properties of SiGe nanowires (NWs) grown by molecular beam epitaxy (MBE) in ordered arrays on SiO2/Si(111) substrates. The production method employs Au catalysts with self-limited sizes deposited in SiO2-free sites opened-up in the substrate by focused ion beam patterning for the preferential nucleation and growth of these well-organized NWs. The NWs thus produced have a diameter of 200 nm, a length of 200 nm, and a Ge concentration x = 0.15. Their photoluminescence (PL) spectra were measured at low temperatures (from 6 to 25 K) with excitation at 405 and 458 nm. There are four major features in the energy range of interest (980-1120 meV) at energies of 1040.7, 1082.8, 1092.5, and 1098.5 meV, which are assigned to the NW-transverse optic (TO) Si-Si mode, NW-transverse acoustic (TA), Si-substrate-TO and NW-no-phonon (NP) lines, respectively. From these results the NW TA and TO phonon energies are found to be 15.7 and 57.8 meV, respectively, which agree very well with the values expected for bulk Si1- x Ge x with x = 0.15, while the measured NW NP energy of 1099 meV would indicate a bulk-like Ge concentration of x = 0.14. Both of these concentrations values, as determined from PL, are in agreement with the target value. The NWs are too large in diameter for a quantum confinement induced energy shift in the band gap. Nevertheless, NW PL is readily observed, indicating that efficient carrier recombination is occurring within the NWs.

Ferromagnetic Mn-doped Si0.3Ge0.7 nanodots self-assembled on Si(100).

Densely packed epitaxial Mn-doped Si(0.3)Ge(0.7) nanodots self-assembled on Si(100) have been obtained. Their structural properties were studied using reflection high-energy electron diffraction, energy dispersive x-ray diffraction, atomic force microscopy, extended x-ray absorption fine structure measurements and high-resolution transmission electron microscopy. Mn(5)Ge(1)Si(2) crystallites embedded in Si(0.3)Ge(0.7) were found. They exhibit a ferromagnetic behaviour with a Curie temperature of about 225 K.