Electrical molecular switch addressed by chemical stimuli.

We demonstrate that the conductance switching of benzo-bis(imidazole) molecules upon protonation depends on the lateral functional groups. The protonated H-substituted molecule shows a higher conductance than the neutral one (Gpro > Gneu), while the opposite (Gneu > Gpro) is observed for a molecule laterally functionalized by amino-phenyl groups. These results are demonstrated at various scale lengths: self-assembled monolayers, tiny nanodot-molecule junctions and single molecules. From ab initio theoretical calculations, we conclude that for the H-substituted molecule, the result Gpro > Gneu is correctly explained by a reduction of the LUMO-HOMO gap, while for the amino-phenyl functionnalized molecule, the result Gneu > Gpro is consistent with a shift of the HOMO, which reduces the density of states at the Fermi energy.

Conductance switching at the nanoscale of diarylethene derivative self-assembled monolayers on La0.7Sr0.3MnO3.

We report on the phosphonic acid route for the grafting of functional molecules, optical switch (dithienylethene diphosphonic acid, DDA), on La0.7Sr0.3MnO3 (LSMO). Compact self-assembled monolayers (SAMs) of DDA are formed on LSMO as studied by topographic atomic force microscopy (AFM), ellipsometry, water contact angle measurements and X-ray photoemission spectroscopy (XPS). The conducting AFM measurements show that the electrical conductance of LSMO/DDA is about 3 decades below that of a bare LSMO substrate. Moreover, the presence of the DDA SAM suppresses the known conductance switching of the LSMO substrate that is induced by mechanical and/or bias constraints during C-AFM measurements. A partial light-induced conductance switching between the open and closed forms of the DDA is observed for the LSMO/DDA/C-AFM tip molecular junctions (closed/open conductance ratio of about 8). We show that, in the case of long-time exposure to UV light, this feature can be masked by a non-reversible decrease (a factor of about 15) of the conductance of the LSMO electrode.

Charge transport through redox active [H7P8W48O184]33- polyoxometalates self-assembled onto gold surfaces and gold nanodots.

Polyoxometalates (POMs) are redox-active molecular oxides, which attract growing interest for their integration into nano-devices, such as high-density data storage non-volatile memories. In this work, we investigated the electrostatic deposition of the negatively charged [H7P8W48O184]33- POM onto positively charged 8-amino-1-octanethiol self-assembled monolayers (SAMs) preformed onto gold substrates or onto an array of gold nanodots. The ring-shaped [H7P8W48O184]33- POM was selected as an example of large POMs with high charge storage capacity. To avoid the formation of POM aggregates onto the substrates, which would introduce variability in the local electrical properties, special attention has to be paid to the preformed SAM seeding layer, which should itself be deprived of aggregates. Where necessary, rinsing steps were found to be crucial to eliminate these aggregates and to provide uniformly covered substrates for subsequent POM deposition and electrical characterizations. This especially holds for commercially available gold/glass substrates while these rinsing steps were not essential in the case of template stripped gold of very low roughness. Charge transport through the related molecular junctions and nanodot molecule junctions (NMJs) has been probed by conducting-AFM. We analyzed the current-voltage curves with different models: electron tunneling though the SAMs (Simmons model), transition voltage spectroscopy (TVS) method or molecular single energy level mediated transport (Landauer equation) and we discussed the energetics of the molecular junctions. We concluded to an energy level alignment of the alkyl spacer and POM lowest occupied molecular orbitals (LUMOs), probably due to dipolar effects.

Physical mechanisms involved in the formation and operation of memory devices based on a monolayer of gold nanoparticle-polythiophene hybrid materials.

Understanding the physical and chemical mechanisms occurring during the forming process and operation of an organic resistive memory device is a requisite for better performance. Various mechanisms were suggested in vertically stacked memory structures, but the analysis remains indirect and needs destructive characterization (e.g. analysis of the cross-section to access the organic layers sandwiched between electrodes). Here, we report a study on a planar, monolayer thick, hybrid nanoparticle/molecule device (10 nm gold nanoparticles embedded in an electro-generated poly(2-thienyl-3,4-(ethylenedioxy)thiophene) layer), combining in situ physical (scanning electron microscopy, physicochemical thermogravimetry and mass spectroscopy, and Raman spectroscopy) and electrical (temperature dependent current-voltage) characterization on the same device. We demonstrate that the forming process causes an increase in the gold particle size, almost 4 times larger than the starting nanoparticles, and that the organic layer undergoes a significant chemical rearrangement from an sp3 to sp2 amorphous carbon material. Temperature dependent electrical characterization of this nonvolatile memory confirms that the charge transport mechanism in the device is consistent with a trap-filled space charge limited current in the off state, with the sp2 amorphous carbon material containing many electrically active defects.

ICTV Virus Taxonomy Profile: Dicistroviridae.

Dicistroviridae is a family of small non-enveloped viruses with monopartite, linear, positive-sense RNA genomes of approximately 8-10 kb. Viruses of all classified species infect arthropod hosts, with some having devastating economic consequences, such as acute bee paralysis virus in domesticated honeybees and taura syndrome virus in shrimp farming. Conversely, the host specificity and other desirable traits exhibited by several members of this group make them potential natural enemies for intentional use against arthropod pests, such as triatoma virus against triatomine bugs that vector Chagas disease. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Dicistroviridae which is available at www.ictv.global/report/dicistroviridae.

ICTV Virus Taxonomy Profile: Iflaviridae.

Iflaviridae is a family of small non-enveloped viruses with monopartite, positive-stranded RNA genomes of approximately 9-11 kilobases. Viruses of all classified species infect arthropod hosts, with the majority infecting insects. Both beneficial and pest insects serve as hosts, and infections can be symptomless (Nilaparvatalugens honeydew virus 1) or cause developmental abnormalities (deformed wing virus), behavioural changes (sacbrood virus) and premature mortality (infectious flacherie virus). The host range has not been examined for most members. The most common route of infection for iflaviruses is the ingestion of virus-contaminated food sources. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Iflaviridae, which is available at www.ictv.global/report/iflaviridae.

The influence of fibril composition and dimension on the performance of paper gated oxide transistors.

Paper electronics is a topic of great interest due the possibility of having low-cost, disposable and recyclable electronic devices. The final goal is to make paper itself an active part of such devices. In this work we present new approaches in the selection of tailored paper, aiming to use it simultaneously as substrate and dielectric in oxide based paper field effect transistors (FETs). From the work performed, it was observed that the gate leakage current in paper FETs can be reduced using a dense microfiber/nanofiber cellulose paper as the dielectric. Also, the stability of these devices against changes in relative humidity is improved. On other hand, if the pH of the microfiber/nanofiber cellulose pulp is modified by the addition of HCl, the saturation mobility of the devices increases up to 16 cm(2) V(-1) s(-1), with an ION/IOFF ratio close to 10(5).

Water electrolysis and energy harvesting with zero-dimensional ion-sensitive field-effect transistors.

The relationship of the gas bubble size to the size distribution critically influences the effectiveness of electrochemical processes. Several optical and acoustical techniques have been used to characterize the size and emission frequency of bubbles. Here, we used zero-dimensional (0D) ion-sensitive field-effect transistors (ISFETs) buried under a microbath to detect the emission of individual bubbles electrically and to generate statistics on the bubble emission time. The bubble size was evaluated via a simple model of the electrolytic current. We suggest that energy lost during water electrolysis could be used to generate electric pulses at an optimal efficiency with an array of 0D ISFETs.

Probing the biophysical interplay between a viral genome and its capsid.

The interaction between a viral capsid and its genome governs crucial steps in the life cycle of a virus, such as assembly and genome uncoating. Tuning cargo-capsid interactions is also essential for successful design and cargo delivery in engineered viral systems. Here we investigate the interplay between cargo and capsid for the picorna-like Triatoma virus using a combined native mass spectrometry and atomic force microscopy approach. We propose a topology and assembly model in which heterotrimeric pentons that consist of five copies of structural proteins VP1, VP2 and VP3 are the free principal units of assembly. The interpenton contacts are established primarily by VP2. The dual role of the genome is first to stabilize the densely packed virion and, second, on an increase in pH to trigger uncoating by relaxing the stabilizing interactions with the capsid. Uncoating occurs through a labile intermediate state of the virion that reversibly disassembles into pentons with the concomitant release of protein VP4.

Dupuytren's disease presentation, referral pathways and resource utilisation in Europe: regional analysis of a surgeon survey and patient chart review.

AIM: We explored the management of Dupuytren's disease (DD) using a surgeon survey and patient chart review. METHODS: Twelve countries participated: Denmark, Finland, Sweden (Nordic region); Czech Republic, Hungary, Poland (East); France, Germany, the Netherlands, United Kingdom (West); Italy, Spain (Mediterranean). A random sample of orthopaedic/plastic surgeons (N = 687) with 3-30 years' experience was asked about Dupuytren's contracture procedures performed during the previous 12 months. Information ≤ 5 consecutive patients per surgeon was extracted from patient charts (N = 3357). RESULTS: Overall, 84% of participants were orthopaedic surgeons; 56% of surgeons were hand specialists. Deciding factors for fasciectomy and dermofasciectomy were consistent across regions: metacarpophalangeal (MP) or proximal interphalangeal contracture > 45°, recurrent contracture, and high expectations for success. Deciding factors for percutaneous needle fasciotomy were less consistent across regions, but the leading factor was MP flexion < 20°. Overall, 49% of diagnoses and 55% of referrals were made by a general practitioner (GP), with regional variation: 31-77% for GP diagnoses and 36-81% for GP referrals. There were also differences in admission status (e.g. 9% of Nordic patients and 80% of Eastern patients were treated as inpatients). Most patients were treated in public hospitals and most procedures were covered by public health insurance. CONCLUSIONS: We found regional variations in surgical practice, patient characteristics and referral patterns. Understanding current diagnosis and treatment patterns, in relation to regional differences in health economics, may improve physicians' diagnosis of DD and guide patients towards appropriate, customised management plans.

Surgical management of Dupuytren's contracture in Europe: regional analysis of a surgeon survey and patient chart review.

AIM: We explored regional variations in the surgical management of patients with Dupuytren's contracture (DC) in 12 European countries using a surgeon survey and patient chart review. METHODS: Twelve countries participated: Denmark, Finland, Sweden (Nordic region); Czech Republic, Hungary, Poland (East); France, Germany, the Netherlands, UK (West); Italy, Spain (Mediterranean). For the survey, a random sample of orthopaedic/plastic surgeons (n = 687) with 3-30 years' experience was asked about DC procedures performed during the previous 12 months. For the chart review (n = 3357), information from up to five consecutive patients was extracted. Descriptive statistics are reported. RESULTS: Ninety-five per cent of all surgeons used fasciectomy for DC, followed by fasciotomy (70%), dermofasciectomy (38%) and percutaneous needle fasciotomy (35%). Most surgeons were satisfied with fasciectomy over other procedures. Recommended time away from work and duration of physical therapy increased with the invasiveness of the procedure. The intra-operative complication rate was 4.0%; the postoperative complication rate was 34%. Overall, ≥ 97% of the procedures were rated by surgeons as having a positive outcome. Across all regions, 54% of patients had no nodules or contracture after the procedures. Only 2% of patients required retreatment within the first year of surgery. Important inter- and intraregional differences in these aspects of patient management are described. CONCLUSIONS: Understanding current regional treatment patterns and their relationships to country-specific health systems may facilitate earlier identification of, and intervention for, DD and help to optimise the overall treatment for patients with this chronic condition.

Cryo-electron microscopy reconstructions of triatoma virus particles: a clue to unravel genome delivery and capsid disassembly.

Triatoma virus (TrV) is a member of the insect virus family Dicistroviridae and consists of a small, non-enveloped capsid that encloses its positive-sense ssRNA genome. Using cryo-transmission electron microscopy and three-dimensional reconstruction techniques combined with fitting of the available crystallographic models, this study analysed the capsids corresponding to mature and several RNA-empty TrV particles. After genome release, the resulting reconstruction of the empty capsids displayed no prominent conformational changes with respect to the full virion capsid. The results showed that RNA delivery led to empty capsids with an apparent overall intact protein shell and suggested that, in a subsequent step, empty capsids disassemble into small symmetrical particles. Contrary to what is observed upon genome release in mammalian picornaviruses, the empty TrV capsid maintained a protein shell thickness and size identical to that in full virions.

Trends in G-CSF use in 990 patients after EORTC and ASCO guidelines.

BACKGROUND: Although international guidelines have standardised conditions for G-CSF administration, real practice seems to vary. PATIENTS AND METHODS: A large survey was undertaken in France following a three-step method. Data concerning 990 patients in seven main indications were collected prospectively and analysed for their compliance with international guidelines. RESULTS: G-CSF prescription rate varied from 81% in non-Hodgkin lymphoma (NHL), 55% in ovarian, 44% in breast and 21% in colorectal cancer. The main criteria for G-CSF administration were a chemotherapy regimen with a high risk of neutropaenia (65%) and associated risk factors (51%). Public hospital practitioners prescribed G-CSF more frequently as primary prophylaxis, whereas prescriptions of recently graduated practitioners (or=16 years) were often proposed as secondary prophylaxis or as G-CSF therapy, i.e. during ongoing neutropaenia. In prophylactic settings, administration schedules were highly variable depending on molecules, with a first day of administration between days 1 and 3 after chemotherapy in 66%, but before the end of the chemotherapy infusion in 13% of the cases. Concerning lenograstim (38% of prescriptions) and filgrastim (20%), the mean treatment duration was 5.5 days, significantly shorter than in 1999 (7.8 days). CONCLUSION: G-CSF prescription was mainly in compliance with international guidelines. However, some too early administrations during chemotherapy are at risk of increased myelosuppression and should be more clearly disadvised in next international guidelines.

Crystallization and preliminary crystallographic analysis of fragaceatoxin C, a pore-forming toxin from the sea anemone Actinia fragacea.

Sea anemones produce water-soluble toxins that have the ability to interact with cell membranes and form pores within them. The mechanism of pore formation is based on an initial binding step followed by oligomerization and membrane insertion. Although the final structure of the pore remains unclear, biochemical studies indicate that it consists of a tetramer with a functional radius of approximately 1.1 nm. Since four monomers seem to be insufficient to build a pore of this size, the currently accepted model suggests that lipids might also participate in its structure. In this work, the crystallization and preliminary crystallographic analysis of two crystal forms of fragaceatoxin C (FraC), a newly characterized actinoporin from Actinia fragacea, are described. The crystals diffracted up to 1.8 A resolution and the preliminary molecular-replacement solution supports an oligomeric structure of about 120 A in diameter.

Phasing of the Triatoma virus diffraction data using a cryo-electron microscopy reconstruction.

The blood-sucking reduviid bug Triatoma infestans, one of the most important vector of American human trypanosomiasis (Chagas disease) is infected by the Triatoma virus (TrV). TrV has been classified as a member of the Cripavirus genus (type cricket paralysis virus) in the Dicistroviridae family. This work presents the three-dimensional cryo-electron microscopy (cryo-EM) reconstruction of the TrV capsid at about 25 A resolution and its use as a template for phasing the available crystallographic data by the molecular replacement method. The main structural differences between the cryo-EM reconstruction of TrV and other two viruses, one from the same family, the cricket paralysis virus (CrPV) and the human rhinovirus 16 from the Picornaviridae family are presented and discussed.

A plate holder for non-destructive testing of mesophase crystallization assays.

Here, we describe a goniometer holder to mount standard 96-well crystallization plates directly onto the goniometer head of an oscillation camera. This attachment was designed to check crystallization conditions straight from the crystallization plates under X-rays, and was proven to be useful for checking small crystals and solutions that destabilize monoolein-based lipidic cubic phase (LCP) crystallization experiments. A quick procedure for setting up LCP assays employing commercially available instruments is also reported.

Indicators to assess temporal genetic diversity in the French Catalogue: no losses for maize and peas.

The aim of this study, led by the GEVES (Research and Control Group for Varieties and Seeds), was to suggest indicators to assess the diversity available to farmers since the French Official Catalogue for Plant Varieties and Species was initiated. The largest datasets of 1990 inbred maize lines and 578 pea lines from the last 50 years were analysed using morphological and enzymatic parameters. Lines were grouped into three to five periods. Genetic diversity was estimated in each period from morphological and enzymatic markers by computing numerous indices, such as the number of classes of scores for each characteristic, allelic richness or genetic diversity index (H ( e )). Population differentiation parameters (G(ST), G(ST)', F(ST), Q(ST)) were also estimated between periods. While genetic diversity computed from distinction, uniformity, stability traits was more marked for maize (0.66) than for garden peas (0.35) or feed peas (0.29), the opposite trend was observed with enzymes, resulting in a genetic diversity of 0.43, 0.35 and 0.22 for garden peas, feed peas and maize, respectively. However, no significant changes in genetic diversity were observed over time, and genetic differentiation was slight between periods. All our results demonstrated that no significant reduction in the diversity available to farmers had been observed since initiation of the French Catalogue. The H ( e ) was a good indicator providing a quantitative estimate of genetic diversity, but it should be interpreted alongside a more precise indicator such as allelic richness or the number of classes for morphological characteristics.

Electron transport through rectifying self-assembled monolayer diodes on silicon: Fermi-level pinning at the molecule-metal interface.

We report the synthesis and characterization of molecular rectifying diodes on silicon using sequential grafting of self-assembled monolayers of alkyl chains bearing a pi group at their outer end (Si/sigma-pi/metal junctions). We investigate the structure-performance relationships of these molecular devices, and we examine the extent to which the nature of the pi end group (change in the energy position of their molecular orbitals) drives the properties of these molecular diodes. Self-assembled monolayers of alkyl chains (different chain lengths from 6 to 15 methylene groups) functionalized by phenyl, anthracene, pyrene, ethylene dioxythiophene, ethylene dioxyphenyl, thiophene, terthiophene, and quaterthiophene were synthesized and characterized by contact angle measurements, ellipsometry, Fourier transform infrared spectroscopy, and atomic force microscopy. We demonstrate that reasonably well-packed monolayers are obtained in all cases. Their electrical properties were assessed by dc current-voltage characteristics and high-frequency (1-MHz) capacitance measurements. For all of the pi groups investigated here, we observed rectification behavior. These results extend our preliminary work using phenyl and thiophene groups (Lenfant et al., Nano Lett. 2003, 3, 741). The experimental current-voltage curves were analyzed with a simple analytical model, from which we extracted the energy position of the molecular orbital of the pi group in resonance with the Fermi energy of the electrodes. We report experimental studies of the band lineup in these silicon/alkyl pi-conjugated molecule/metal junctions. We conclude that Fermi-level pinning at the pi group/metal interface is mainly responsible for the observed absence of a dependence of the rectification effect on the nature of the pi groups, even though the groups examined were selected to have significant variations in their electronic molecular orbitals.

Dealing with metastatic breast cancer in elderly women: results from a French study on a large cohort carried out by the 'Observatory on Elderly Patients'.

BACKGROUND: Treatment of elderly patients with metastatic breast cancer (MBC) is not clearly defined and seems to vary according to the subjective appreciation of the physician. PATIENTS AND METHODS: After interviewing 107 French specialists qualified in oncology, data concerning 1009 MBC patients were collected: 500 patients were between 65 and 74 years and 509 were >75 years of age. Differences in diagnosis and treatment strategy were analyzed for both age groups to identify the physician's criteria of choice and the eventual use of the geriatric assessment among those criteria. RESULTS: At diagnosis, synchronous metastatic disease was more frequent in patients over 75 years old (52% versus 39%; P<0.001). Physicians indicated that treatment was based on age and on a subjective evaluation of the patient's general status. Sixty-eight per cent of younger patients and only 31% of older ones received chemotherapy (P<0.001). In the older group drug doses were lower than those usually recommended in three-quarters of cases. Only 10% of physicians considered that they under-treat patients using the FEC 50 regimen. Over 75 years of age, hormone therapy was offered to most patients, including 8% with hormone-independent tumors. Geriatric covariates were never considered. Geriatricians rarely, if ever, played a role in the therapeutic decision. CONCLUSIONS: Inclusion of elderly patients with MBC in prospective trials is warranted to define standards of care and reduce heterogeneity in the decision-making process.