The atom pencil: serial writing in the sub-micrometre domain

The atom pencil we describe here is a versatile tool that writes arbitrary structures by atomic deposition in a serial lithographic process. This device consists of a transversely laser-cooled and collimated cesium atomic beam that passes through a 4-pole atom-flux concentrator and impinges on to micron- and sub-micron-sized apertures. The aperture translates above a fixed substrate and enables the writing of sharp features with sizes down to 280 nm. We have investigated the writing and clogging properties of an atom pencil tip fabricated from silicon oxide pyramids perforated at the tip apex with a sub-micron aperture

Mitochondrial dysfunction and biogenesis: do ICU patients die from mitochondrial failure?

Mitochondrial functions include production of energy, activation of programmed cell death, and a number of cell specific tasks, e.g., cell signaling, control of Ca2+ metabolism, and synthesis of a number of important biomolecules. As proper mitochondrial function is critical for normal performance and survival of cells, mitochondrial dysfunction often leads to pathological conditions resulting in various human diseases. Recently mitochondrial dysfunction has been linked to multiple organ failure (MOF) often leading to the death of critical care patients. However, there are two main reasons why this insight did not generate an adequate resonance in clinical settings. First, most data regarding mitochondrial dysfunction in organs susceptible to failure in critical care diseases (liver, kidney, heart, lung, intestine, brain) were collected using animal models. Second, there is no clear therapeutic strategy how acquired mitochondrial dysfunction can be improved. Only the benefit of such therapies will confirm the critical role of mitochondrial dysfunction in clinical settings. Here we summarized data on mitochondrial dysfunction obtained in diverse experimental systems, which are related to conditions seen in intensive care unit (ICU) patients. Particular attention is given to mechanisms that cause cell death and organ dysfunction and to prospective therapeutic strategies, directed to recover mitochondrial function. Collectively the data discussed in this review suggest that appropriate diagnosis and specific treatment of mitochondrial dysfunction in ICU patients may significantly improve the clinical outcome

Regularity of the vibrational spectrum of the CS[sub 2] in the Σ[sub g][sup +] state: Our previous results revisited

International audienceIn previous experiments, a nearly complete vibrational spectrum of the CS2 molecule in the Σg+ state has been obtained using a laser induced fluorescence method. The statistical tests of the random matrix theory, applied on this spectrum, suggest a transition to quantum chaos. The aim of this letter is to show that these statistical results are biased because of a nonsingle excitation of the molecule. This is experimentally confirmed by high-resolution new experiments in supersonic jet, using the powerful laser chain of the french project for the isotopic separation of uranium by laser (SILVA project)

IR-UV double resonance experiment using a CO and a CuHBr (HyBrID) laser pumped dye laser: application to the spectroscopy of CS2

International audienceAn Infrared-Ultraviolet Double Resonance (IR-UV DR) experiment has been built in order to resolve and identify single rotational levels in dense molecular spectra. The system is based on a CO laser, working on the CO fundamental transition (Δ v=1), and a frequency doubled dye laser pumped by a recently developed copper vapor "HyBrID " or "CuHBr" laser. We demonstrate the promising nature of the CuHBr laser as a pump laser for high power dye lasers. Different excitation schemes can be used with this experiment in order to obtain information about excited electronic states. We also report here preliminary results on the spectroscopy of the carbon disulfide (CS 2) molecule

Atomic nanofabrication . . . .

The method of neutral atom lithography allows to transfer a 2D intensity modulation of an atomic beam imposed by an inhomogeneous light field to a substrate. The complexity of the pattern depends on the properties of the light field constructed from the superposition of multiple laser beams. For the design of suitable light fields we present a mathematical model with a corresponding numerical simulation of the so called inverse problem. Furthermore, details of an experiment carried out with a holographically reconstructed light field are discussed

Green Tea Polyphenols Stimulate Mitochondrial Biogenesis and Improve Renal Function after Chronic Cyclosporin A Treatment in Rats

Our previous studies showed that an extract from Camellia sinenesis (green tea), which contains several polyphenols, attenuates nephrotoxicity caused by cyclosporine A (CsA). Since polyphenols are stimulators of mitochondrial biogenesis (MB), this study investigated whether stimulation of MB plays a role in green tea polyphenol protection against CsA renal toxicity. Rats were fed a powdered diet containing green tea polyphenolic extract (0.1%) starting 3 days prior to CsA treatment (25 mg/kg, i.g. daily for 3 weeks). CsA alone decreased renal nuclear DNA-encoded oxidative phosphorylation (OXPHOS) protein ATP synthase-β (AS-β) by 42%, mitochondrial DNA (mtDNA)-encoded OXPHOS protein NADH dehydrogenase-3 (ND3) by 87% and their associated mRNAs. Mitochondrial DNA copy number was also decreased by 78% by CsA. Immunohistochemical analysis showed decreased cytochrome c oxidase subunit IV (COX-IV), an OXPHOS protein, in tubular cells. Peroxisome proliferator-activated receptor-γ coactivator (PGC)-1α, the master regulator of MB, and mitochondrial transcription factor-A (Tfam), the transcription factor that regulates mtDNA replication and transcription, were 42% and 90% lower, respectively, in the kidneys of CsA-treated than in untreated rats. These results indicate suppression of MB by chronic CsA treatment. Green tea polyphenols alone and following CsA increased AS-β, ND3, COX-IV, mtDNA copy number, PGC-1α mRNA and protein, decreased acetylated PGC-1α, and increased Tfam mRNA and protein. In association with suppressed MB, CsA increased serum creatinine, caused loss of brush border and dilatation of proximal tubules, tubular atrophy, vacuolization, apoptosis, calcification, and increased neutrophil gelatinase-associated lipocalin expression, leukocyte infiltration, and renal fibrosis. Green tea polyphenols markedly attenuated CsA-induced renal injury and improved renal function. Together, these results demonstrate that green tea polyphenols attenuate CsA-induced kidney injury, at least in part, through the stimulation of MB