Growth and magnetic characterization of Co nanoparticles obtained by femtosecond pulsed laser deposition.

We present a detailed study on the morphology and magnetic properties of Co nanostructures deposited onto oxidized Si substrates by femtosecond pulsed laser deposition. Generally, Co disks of nanometric dimensions are obtained just above the ablation threshold, with a size distribution characterized by an increasingly larger number of disks as their size diminishes, and with a maximum disk size that depends on the laser power density. In Au/Co/Au structures, in-plane magnetic anisotropy is observed in all cases, with no indication of superparamagnetism regardless of the amount of material or the laser power density. Magnetic force microscopy observations show coexistence of single-domain and vortex states for the magnetic domain structure of the disks. Superconducting quantum interference device magnetometry and x-ray magnetic circular dichroism measurements point to saturation magnetization values lower than the bulk, probably due to partial oxidation of the Co resulting from incomplete coverage by the Au capping layer.

Cardiac Toxicity in Selective Serotonin Reuptake Inhibitor Users.

Several classes of recreational and prescription drugs have been associated with an increased risk of cardiovascular disease and the occurrence of arrhythmias, which may be involved in sudden deaths in chronic users even at therapeutic doses. The study presented herein focuses on pathological changes involving the heart, which may be caused by selective serotonin reuptake inhibitor use and their possible role in the occurrence of sudden cardiac death. A total of 40 cases were included in the study and were divided evenly into 2 groups: 20 cases of patients treated with selective serotonin reuptake inhibitors and 20 cases of sudden deaths involving patients void of any drug treatment. The first group included 16 patients treated with citalopram and 4 with sertraline. Autopsies, histology, biochemistry, and toxicology were performed in all cases. Pathological changes in selective serotonin reuptake inhibitor users consisted of various degrees of interstitial and perivascular fibrosis as well as a small degree of perineural fibrosis within the myocardium of the left ventricle. Within the limits of the small number of investigated cases, the results of this study seem to confirm former observations on this topic, suggesting that selective serotonin reuptake inhibitors may play a potential, causative role in the pathogenesis of sudden deaths in chronic users even at therapeutic concentrations.

The effects of some variables on CO2 laser-MAG hybrid welding

The CO2-laser-MAG hybrid welding process has been shown to be a productive choice for the welding industry, being used in e.g. the shipbuilding, pipe and beam manufacturing, and automotive industries. It provides an opportunity to increase the productivity of welding of joints containing air gaps compared with autogenous laser beam welding, with associated reductions in distortion and marked increases in welding speeds and penetration in comparison with both arc and autogenous laser welding. The literature study indicated that the phenomena of laser hybrid welding are mostly being studied using bead-on-plate welding or zero air gap configurations. This study shows it very clearly that the CO2 laser-MAG hybrid welding process is completely different, when there is a groove with an air gap. As in case of industrial use it is excepted that welding is performed for non-zero grooves, this study is of great importance for industrial applications. The results of this study indicate that by using a 6 kW CO2 laser-MAG hybrid welding process, the welding speed may also be increased if an air gap is present in the joint. Experimental trials indicated that the welding speed may be increased by 30-82% when compared with bead-on-plate welding, or welding of a joint with no air gap i.e. a joint prepared as optimum for autogenous laser welding. This study demonstrates very clearly, that the separation of the different processes, as well as the relative configurations of the processes (arc leading or trailing) affect welding performance significantly. These matters influence the droplet size and therefore the metal transfer mode, which in turn determined the resulting weld quality and the ability to bridge air gaps. Welding in bead-onplate mode, or of an I butt joint containing no air gap joint is facilitated by using a leading torch. This is due to the preheating effect of the arc, which increases the absorptivity of the work piece to the laser beam, enabling greater penetration and the use of higher welding speeds. With an air gap present, air gap bridging is more effectively achieved by using a trailing torch because of the lower arc power needed, the wider arc, and the movement of droplets predominantly towards the joint edges. The experiments showed, that the mode of metal transfer has a marked effect on gap bridgeability. Transfer of a single droplet per arc pulse may not be desirable if an air gap is present, because most of the droplets are directed towards the middle of the joint where no base material is present. In such cases, undercut is observed. Pulsed globular and rotational metal transfer modes enable molten metal to also be transferred to the joint edges, and are therefore superior metal transfer modes when bridging air gaps. It was also found very obvious, that process separation is an important factor in gap bridgeability. If process separation is too large, the resulting weld often exhibits sagging, or no weld may be formed at all as a result of the reduced interaction between the component processes. In contrast, if the processes are too close to one another, the processing region contains excess molten metal that may create difficulties for the keyhole to remain open. When the distance is optimised - i.e. a separation of 0-4 mm in this study, depending on the welding speed and beam-arc configuration - the processes act together, creating beneficial synergistic effects. The optimum process separation when using a trailing torch was found to be shorter (0-2 mm) than when a leading torch is used (2-4 mm); a result of the facilitation of weld pool motion when the latter configuration is adopted. This study demonstrates, that the MAG process used has a strong effect on the CO2-laser-MAG hybrid welding process. The laser beam welding component is relatively stable and easy to manage, with only two principal processing parameters (power and welding speed) needing to be adjusted. In contrast, the MAG process has a large number of processing parameters to optimise, all of which play an important role in the interaction between the laser beam and the arc. The parameters used for traditional MAG welding are often not optimal in achieving the most appropriate mode of metal transfer, and weld quality in laser hybrid welding, and must be optimised if the full range of benefits provided by hybrid welding are to be realised.

Prevenção da xerostomia e da mucosite oral induzidas por radioterapia com uso do laser de baixa potência

OBJETIVO: Verificar se o uso do laser de InGaAlP com comprimento de onda de 685 nm pode reduzir a incidência de xerostomia, gravidade da mucosite oral e da dor associada à mucosite em pacientes portadores de câncer de cabeça e pescoço submetidos a radioterapia. MATERIAIS E MÉTODOS: Sessenta pacientes portadores de carcinoma de cabeça e pescoço foram submetidos a radioterapia com dose diária de 1,8 a 2,0 Gy e dose final de 45 a 72 Gy. O volume salivar foi medido nos dias um, 15, ao final do tratamento e após 15 e 30 dias, e a mucosite oral em avaliações semanais. Vinte e nove pacientes se submeteram a radioterapia sem laser e 31 foram submetidos a radioterapia e laser com dose diária de 2 joules/cm² em pontos pré-determinados da mucosa oral e glândulas parótida e submandibular. RESULTADOS: No grupo submetido a radioterapia e laser, a incidência de mucosite (p < 0,001) e dor (p < 0,016) foram significativamente menores e o volume salivar se manteve maior (p < 0,001) durante e após o tratamento. CONCLUSÃO: Os pacientes submetidos à associação de radioterapia e laser tiveram menor incidência de xerostomia, mucosite oral e dor quando comparados ao grupo de radioterapia sem laser, com resultados com significância estatística.

Selective serotonin reuptake inhibitor antidepressant use in first trimester pregnancy and risk of specific congenital anomalies: a European register-based study.

Evidence of an association between early pregnancy exposure to selective serotonin reuptake inhibitors (SSRI) and congenital heart defects (CHD) has contributed to recommendations to weigh benefits and risks carefully. The objective of this study was to determine the specificity of association between first trimester exposure to SSRIs and specific CHD and other congenital anomalies (CA) associated with SSRI exposure in the literature (signals). A population-based case-malformed control study was conducted in 12 EUROCAT CA registries covering 2.1 million births 1995-2009 including livebirths, fetal deaths from 20 weeks gestation and terminations of pregnancy for fetal anomaly. Babies/fetuses with specific CHD (n = 12,876) and non-CHD signal CA (n = 13,024), were compared with malformed controls whose diagnosed CA have not been associated with SSRI in the literature (n = 17,083). SSRI exposure in first trimester pregnancy was associated with CHD overall (OR adjusted for registry 1.41, 95 % CI 1.07-1.86, fluoxetine adjOR 1.43 95 % CI 0.85-2.40, paroxetine adjOR 1.53, 95 % CI 0.91-2.58) and with severe CHD (adjOR 1.56, 95 % CI 1.02-2.39), particularly Tetralogy of Fallot (adjOR 3.16, 95 % CI 1.52-6.58) and Ebstein's anomaly (adjOR 8.23, 95 % CI 2.92-23.16). Significant associations with SSRI exposure were also found for ano-rectal atresia/stenosis (adjOR 2.46, 95 % CI 1.06-5.68), gastroschisis (adjOR 2.42, 95 % CI 1.10-5.29), renal dysplasia (adjOR 3.01, 95 % CI 1.61-5.61), and clubfoot (adjOR 2.41, 95 % CI 1.59-3.65). These data support a teratogenic effect of SSRIs specific to certain anomalies, but cannot exclude confounding by indication or associated factors.

Deposition and characterization of lines printed through laser-induced forward transfer

The possibility of printing two-dimensional micropatterns of biomolecule solutions is of great interest in many fields of research in biomedicine, from cell-growth and development studies to the investigation of the mechanisms of communication between cells. Although laser-induced forward transfer (LIFT) has been extensively used to print micrometric droplets of biological solutions, the fabrication of complex patterns depends on the feasibility of the technique to print micron-sized lines of aqueous solutions. In this study we investigate such a possibility through the analysis of the influence of droplet spacing of a water and glycerol solution on the morphology of the features printed by LIFT. We prove that it is indeed possible to print long and uniform continuous lines by controlling the overlap between adjacent droplets. We show how, depending on droplet spacing, several printed morphologies are generated, and we offer, in addition, a simple explanation of the observed behavior based on the jetting dynamics characteristic of the LIFT of liquids.

Landslide detection and monitoring capability of boat-based mobile laser scanning along Dieppe coastal cliffs, Normandy

Integrated in a wide research assessing destabilizing and triggering factors to model cliff dynamic along the Dieppe's shoreline in High Normandy, this study aims at testing boat-based mobile LiDAR capabilities by scanning 3D point clouds of the unstable coastal cliffs. Two acquisition campaigns were performed in September 2012 and September 2013, scanning (1) a 30-km-long shoreline and (2) the same test cliffs in different environmental conditions and device settings. The potentials of collected data for 3D modelling, change detection and landslide monitoring were afterward assessed. By scanning during favourable meteorological and marine conditions and close to the coast, mobile LiDAR devices are able to quickly scan a long shoreline with median point spacing up to 10cm. The acquired data are then sufficiently detailed to map geomorphological features smaller than 0.5m2. Furthermore, our capability to detect rockfalls and erosion deposits (>m3) is confirmed, since using the classical approach of computing differences between sequential acquisitions reveals many cliff collapses between Pourville and Quiberville and only sparse changes between Dieppe and Belleville-sur-Mer. These different change rates result from different rockfall susceptibilities. Finally, we also confirmed the capability of the boat-based mobile LiDAR technique to monitor single large changes, characterizing the Dieppe landslide geometry with two main active scarps, retrogression up to 40m and about 100,000m3 of eroded materials.

Low-level laser therapy for the prevention of low salivary flow rate after radiotherapy and chemotherapy in patients with head and neck cancer

Abstract Objective: To determine whether low-level laser therapy can prevent salivary hypofunction after radiotherapy and chemotherapy in head and neck cancer patients. Materials and Methods: We evaluated 23 head and neck cancer patients, of whom 13 received laser therapy and 10 received clinical care only. An InGaAlP laser was used intra-orally (at 660 nm and 40 mW) at a mean dose of 10.0 J/cm2 and extra-orally (at 780 nm and 15 mW) at a mean dose of 3.7 J/cm2, three times per week, on alternate days. Stimulated and unstimulated sialometry tests were performed before the first radiotherapy and chemotherapy sessions (N0) and at 30 days after the end of treatment (N30). Results: At N30, the mean salivary flow rates were significantly higher among the laser therapy patients than among the patients who received clinical care only, in the stimulated and unstimulated sialometry tests (p = 0.0131 and p = 0.0143, respectively). Conclusion: Low-level laser therapy, administered concomitantly with radiotherapy and chemotherapy, appears to mitigate treatment-induced salivary hypofunction in patients with head and neck cancer.

Neuroprotection by selective neuronal deletion of Atg7 in neonatal brain injury.

Perinatal asphyxia induces neuronal cell death and brain injury, and is often associated with irreversible neurological deficits in children. There is an urgent need to elucidate the neuronal death mechanisms occurring after neonatal hypoxia-ischemia (HI). We here investigated the selective neuronal deletion of the Atg7 (autophagy related 7) gene on neuronal cell death and brain injury in a mouse model of severe neonatal hypoxia-ischemia. Neuronal deletion of Atg7 prevented HI-induced autophagy, resulted in 42% decrease of tissue loss compared to wild-type mice after the insult, and reduced cell death in multiple brain regions, including apoptosis, as shown by decreased caspase-dependent and -independent cell death. Moreover, we investigated the lentiform nucleus of human newborns who died after severe perinatal asphyxia and found increased neuronal autophagy after severe hypoxic-ischemic encephalopathy compared to control uninjured brains, as indicated by the numbers of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3)-, LAMP1 (lysosomal-associated membrane protein 1)-, and CTSD (cathepsin D)-positive cells. These findings reveal that selective neuronal deletion of Atg7 is strongly protective against neuronal death and overall brain injury occurring after HI and suggest that inhibition of HI-enhanced autophagy should be considered as a potential therapeutic target for the treatment of human newborns developing severe hypoxic-ischemic encephalopathy.

Fotólise no estado estacionário e com pulso de laser de 1-benzociclanonas e de seus derivados a,a -dimetilados

Laser excitation of 0.01 M solutions of 1-indanone (Ia), 1-tetralone (Ib), 1-benzosuberone (Ic), and their a,a -dimethyl derivatives IIa-c, respectively, in benzene, produced transients with maximum absorption at 425 nm, and lifetimes ranging from 62 ns (IIa) to 5.5ms (Ic). Quenching studies using well known triplet quenchers such as 1,3-cyclohexadiene and oxygen demonstrated the triplet nature of these transients. In the presence of hydrogen donors, such as 2-propanol, the triplet state decay of the ketones Ia-c leads to the formation of the corresponding ketyl radicals, i.e. IIIa-c, which show absorption spectra very similar to the parent ketone, with lmax at 430 nm and lifetime in excess of 20 ms. Steady state irradiations show that the a,a -dimethyl ketones IIa and IIc form ortho-alkyl benzaldehydes probably derived from an initial a-cleavage of the corresponding triplet excited states.