Dynamics of quartz tuning fork force sensors used in scanning probe microscopy

We have performed an experimental characterization of the dynamics of oscillating quartz tuning forks which are being increasingly used in scanning probe microscopy as force sensors. We show that tuning forks can be described as a system of coupled oscillators. Nevertheless, this description requires the knowledge of the elastic coupling constant between the prongs of the tuning fork, which has not yet been measured. Therefore tuning forks have been usually described within the single oscillator or the weakly coupled oscillators approximation that neglects the coupling between the prongs. We propose three different procedures to measure the elastic coupling constant: an opto-mechanical method, a variation of the Cleveland method and a thermal noise based method. We find that the coupling between the quartz tuning fork prongs has a strong influence on the dynamics and the measured motion is in remarkable agreement with a simple model of coupled harmonic oscillators. The precise determination of the elastic coupling between the prongs of a tuning fork allows to obtain a quantitative relation between the resonance frequency shift and the force gradient acting at the free end of a tuning fork prong.Comment: 16 pages, 6 figures, 2 Table

Carbon fibre tips for scanning probe microscopy based on quartz tuning fork force sensors

We report the fabrication and the characterization of carbon fibre tips for their use in combined scanning tunnelling and force microscopy based on piezoelectric quartz tuning fork force sensors. We find that the use of carbon fibre tips results in a minimum impact on the dynamics of quartz tuning fork force sensors yielding a high quality factor and consequently a high force gradient sensitivity. This high force sensitivity in combination with high electrical conductivity and oxidation resistance of carbon fibre tips make them very convenient for combined and simultaneous scanning tunnelling microscopy and atomic force microscopy measurements. Interestingly, these tips are quite robust against occasionally occurring tip crashes. An electrochemical fabrication procedure to etch the tips is presented that produces a sub-100 nm apex radius in a reproducible way which can yield high resolution images.Comment: 14 pages, 10 figure

Optical fiber feasibility study in Accelerated Pavement Testing facility

The presented research has been carried out within the European project Intelligent Roads (INTRO). The major objective followed was to assess the potential of optical fiber for pavement monitoring in comparison with classical strain gauges. Thus, both measurement devices have been tested under the same conditions in a full scale Accelerated Pavement Testing (APT) at LAVOC. This facility allows the user to control different parameters such as loading configuration and temperature and, as a matter of facts, limit the disturbances. A total number of 10 strain gauges and 8 optical fibers have been installed and tested for various conditions. This study showed rather consistent and comparable results for both optical fiber and strain gauges measurements. The comparison with calculated deformation also highlighted the consistency of the measurements results. The sensitivity of the measurement system has also been highlighted and permitted to conclude with some recommendations for further developments

Détermination de la présence et de l'efficacité de dope dans les bétons bitumineux

La contribution du phénomène de désenrobage dans l’apparition et la progression de plusieurs dégradations des revêtements est un fait reconnu. Ces dégradations se développent principalement au niveau de la surface de roulement. Néanmoins, les théories et mécanismes qui régissent le phénomène d’adhésion et de cohésion entre les granulats et le liant ne sont toujours pas unanimement décrits de nos jours et une théorie globale fait défaut. L’adhésivité entre liant et granulats fait référence à plusieurs phénomènes physico-chimiques complexes (réaction chimique, énergie de surface, réarrangement moléculaire, viscosité et mouillabilité, etc.) dont les mécanismes réels sont encore peu connus et mal maîtrisés. En ce qui concerne les méthodes d'évaluation de la sensibilité à l'humidité, la plupart de ces méthodes mesurent des propriétés générales telles que la résistance à la traction, au lieu des forces interfaciales réelles. De même, plusieurs essais sont encore en cours d’évaluation afin d'améliorer la capacité de prédire les performances à long terme, la reproductibilité et la corrélation entre les résultats de laboratoire et in situ. L’objectif du projet a été de développer une méthodologie, d’abord à partir d’essais existants puis de proposer un nouvel essai, permettant de déterminer la présence de dopes dans les liants hydrocarbonés et d’en évaluer l’efficacité. Cet objectif a été considéré en tenant compte des différentes pratiques et méthodologies existantes. Le projet de recherche est divisé en plusieurs étapes. La première vise à faire un inventaire des dopes et des essais correspondants utilisés aujourd’hui, ainsi qu’un bilan de leurs interactions connues avec les granulats et liants routiers type. La deuxième étape consiste à effectuer une analyse détaillée de la présence et d’efficacité des dopes d’adhésivité dans les liants hydrocarbonés. Enfin, dans une troisième étape, une nouvelle méthodologie de caractérisation de la présence et de l’efficacité des dopes d’adhésivité est proposée. Il n’existe pas actuellement de méthode faisant référence afin de déterminer la présence d’un dope d’adhésivité dans un liant hydrocarboné et d’en apprécier l’efficacité. Les essais utilisés en Suisse dans ce domaine sont peu nombreux et une comparaison directe entre les résultats des différentes méthodes reste délicate. Les différents essais effectués dans le cadre de cette recherche ont clairement montrés la difficulté à "mesurer" l’adhésivité entre les granulats minéraux et les liants hydrocarbonés. Les conditions d’essais et les caractéristiques mesurées peuvent fortement varier d’un essai à l’autre. Il a surtout été constaté que les essais mécaniques présentent un manque évident de sensibilité pour quantifier les phénomènes d’adhésivité d’un béton bitumineux. La mise au point d’un essai novateur, l’essai d’efficacité d’un dope, a été effectué dans le cadre de cette recherche. Cet essai, basé sur un essai français développé par le Laboratoire Central des Ponts et Chaussées (LCPC), correspond, de par sa simplicité et sa rapidité, à une méthode pertinente de détection de l’efficacité de dopes d’adhésivité dans les liants hydrocarbonés et son application, très accessible, amènerait une réelle amélioration, en amont, de la connaissance de la qualité et d’efficacité des liants dopés. L’essai a démontré des résultats prometteurs et sa simplicité, sa rapidité et son coût faible en font un essai intéressant. La modification et l’amélioration du mode opératoire a permis de réaliser des résultats plus pertinents, pour autant que le mode opératoire soit suivi avec rigueur. L’essai fonctionne correctement avec les liants testés (dopés ou non), mélangés au sable de Fontainebleau traité aux acides, mais n’a pas donné des résultats concluants lors du remplacement du sable de Fontainebleau par des sables provenant des granulats Suisses sélectionnés. L’essai est donc limité actuellement à relever la présence d’un dope d’adhésivité efficace dans un liant hydrocarboné. Au niveau des teneurs en dope, l’essai peut indiquer un surdosage de dope mais ne donne pas la teneur optimale ou minimale pour un granulat choisi. De même, l’essai ne permet pas de détecter la présence d’un dope ayant perdu ses capacités dopantes ou son efficacité dans un liant hydrocarbonés

Safety and efficacy of Taminizer D (dimethylglycine sodium salt) as a feed additive for chickens for fattening

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of Taminizer D (dimethylglycine sodium salt) as a feed additive for chickens for fattening, based on a dossier submitted for the modification of the terms of authorisation of the additive. The product is authorised in the European Union for chickens for fattening at the maximum content of 1,000 mg/kg complete feedingstuffs. The applicant proposed the introduction of an additional manufacturing process, which introduces an impurity (dimethylamino-ethanol (DMAE)) in the additive at concentrations up to 0.09%. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) considered that the proposed modification would not substantially affect the previous assessment as related to the safety of the environment and the efficacy of the product. Since the safety of the active substance was established, the current assessment has dealt with the impurity DMAE. Considering the toxicological profile of DMAE, the estimated intake by the target animal and consumers, and making use of the Threshold of Toxicological Concern (TTC) approach, the Panel concluded that Taminizer D, manufactured by the DMAE route, is safe for both chickens for fattening and consumers, up to the maximum level of 1,000 mg/kg feed. The FEEDAP Panel extends its conclusions about Taminizer D produced by the original method to cover also Taminizer D produced by the new DMAE method. There is minimal risk to users from dust produced as a result of normal handling of the additive. Taminizer D is not irritant to skin but may be irritant to eyes; it is regarded as a potential skin sensitiser. The FEEDAP Panel recommended to set a specification for the DMAE content in the additive

Safety and efficacy of Kelforce \uae (l-glutamic acid, N,N-diacetic acid, tetrasodium salt (GLDA-Na 4 )) as a feed additive for chickens for fattening

l-Glutamic acid, N,N-diacetic acid, tetrasodium salt (GLDA-Na 4 ) (Kelforce \uae ) is sought to be used as a zootechnical feed additive in chickens for fattening to improve the absorption of zinc from feed, reducing zinc emissions through manure and thus, affecting favourably the environment. The product has not been authorised in the European Union as a feed additive. Kelforce \uae is intended to be marketed as a liquid and solid formulation, containing 65 47% and 65 30% of GLDA-Na 4 , respectively. Kelforce \uae is safe for chickens for fattening at the maximum level of 1,000 mg GLDA-Na 4 /kg complete feed. Based on the toxicological profile of GLDA-Na 4 and the consumer exposure to GLDA-Na 4 and to nitrilotriacetic acid trisodium salt (NTA-Na 3 ; an impurity of the additive), the use of Kelforce \uae at the maximum proposed level in feed of chickens for fattening is of no concern for consumer safety. Due to its low inhalation toxicity, the exposure to GLDA-Na 4 is unlikely to pose a risk by inhalation. However, owing to the high-dusting potential of the solid formulation, a risk from such high level of dust, even if toxicologically inert, cannot be excluded. Kelforce \uae is not a skin/eye irritant or skin sensitiser. No risks for the terrestrial compartment were identified at the maximum use level of the additive. Risks for the aquatic compartment cannot be excluded based on the secondary effect of the additive on green algae. In the absence of data, the Panel cannot conclude on the safety for the sediment compartment or the possible ground water contamination. The risk of bioaccumulation and secondary poisoning caused by the additive is considered very low. Owing to the inconsistent and conflicting results from the studies assessed, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) cannot conclude on the efficacy of the additive. The Panel made a recommendation regarding the levels of formaldehyde and cyanide in the active substance

Safety and efficacy of a natural mixture of dolomite plus magnesite and magnesium-phyllosilicates (Fluidol) as feed additive for all animal species

The additive, a natural mixture of dolomite plus magnesite and magnesium-phyllosilicates, is intended to be used as a technological additive (functional groups: anticaking agents) in feedingstuffs for all animal species. The additive is safe in complete feed for dairy cows, piglets and pigs for fattening at a maximum concentration of 20,000 mg/kg. No conclusions can be drawn for all the other animal species/categories. The additive is not genotoxic. As the additive is essentially not absorbed from the gut lumen, the Panel on Additives and Products or Substances used in Animal Feed considers that use of the additive in animal nutrition is safe for consumers of food products from animals fed diets containing the additive. The additive is not an irritant to the eyes and the skin, it is not a skin sensitiser and it is of low toxicity by the inhalation route. The components of the additive (dolomite, magnesite, talc and chlorite) are natural constituents of soil. Consequently, the use of the additive in animal nutrition will not pose a risk to the environment. The additive is effective as an anticaking agent at a minimum inclusion level of 5,000 mg/kg feed

Safety and efficacy of B‐Act® (Bacillus licheniformis DSM 28710) for chickens for fattening and chickens reared for laying

The additive B-Act\uae is a preparation containing viable spores of a strain of Bacillus licheniformis. The additive is intended for use in feed for chickens for fattening and chickens reared for laying at the proposed dose of 1.6 9 109 colony-forming unit (CFU)/kg complete feedingstuffs. B. licheniformis is considered by EFSA to be suitable for the qualified presumption of safety approach for establishing safety. As the identity of the active agent was established and the lack of toxigenic potential and resistance to antibiotics of human or veterinary clinical significance were demonstrated, the additive is presumed safe for the target species, consumers and the environment. In the absence of data, no conclusion can be drawn on the skin/eye irritation or skin sensitisation potential. The dustiness of the preparations tested indicated a potential for users to be exposed via inhalation. B-Act\uae should be considered to have the potential to be a respiratory sensitiser. B-Act\uae at the recommended dose 1.6 9 109 CFU/kg feed has some potential to improve the feed to gain ratio of chickens for fattening. This conclusion can be extended to chickens reared for laying when used at the same dose. B. licheniformis DSM 28710 is compatible with decoquinate, diclazuril, halofuginone, nicarbazin, robenidine hydrochloride, lasalocid A sodium, maduramicin ammonium, monensin sodium, narasin and salinomycin sodium

Safety and efficacy of methylester of conjugated linoleic acid (t10,c12 isomer) for pigs for fattening, sows and cows

A mixture of methylated conjugated linoleic acid (CLA) isomers (t10,c12 and c9,t11) in equal proportions was not genotoxic and caused no reproductive toxicity. In a sub-acute study in dogs, a sub-chronic toxicity study in rats and a chronic study in dogs, no adverse effects were seen up to the highest levels tested. The maximum recommended feed concentration (5 g CLA (t10,c12)-ME from Lutalin (R)/kg feed for piglets, pigs for fattening and sows) or dose (30 g CLA (t10,c12)-ME from Lutrell (R) Pure/cow per day) is considered safe for target species. The CLA content of milk from cows treated with the highest recommended dose did not exceed background values (in milk of untreated cows) for both CLA isomers. An estimate of consumer exposure to both CLA isomers from food from pigs receiving 3 g of both CLA isomers/kg feed is <= 320 mg CLA isomers/person and day. This quantity corresponds to about 9% of the quantity considered safe for 6 months and is considered unlikely to raise concerns for consumer safety. Exposure of users by inhalation of the additive is likely to be minimal. Neither of the products under application, the liquid or the solid product, was tested as such for skin and eye irritation and skin sensitisation. The use of the additive in animal nutrition would not pose a risk to the environment. In pigs for fattening, CLA (t10,c12)-ME has a potential for improving feed to gain ratio. More consistent effects are a reduction in subcutaneous fat, an increase in intramuscular fat and fat firmness. No essential effects were found in sows. Administration of CLA to dairy cows reduces in a dose-dependent manner the fat content of milk, and milk fat yield. Energy balance in early lactation is improved by CLA (t10,c12)-ME; however, reproductive parameters were not influenced

Safety and efficacy of lactic acid and calcium lactate when used as technological additives for all animal species

This opinion concerns the re-authorisation of lactic acid and calcium lactate for use as preservatives in feed and a new authorisation for lactic acid as a preservative in water for drinking. The maximum level of 50 000 mg lactic acid/kg complete feed and 30 000 mg calcium lactate/kg complete feed are considered safe for functional ruminants and pigs. The maximum safe concentration in water for drinking for pigs can be derived from the maximum safe level in feed (15 000 mg lactic acid/L water). No conclusions on the safety of lactic acid in pre-ruminants and poultry can be drawn. These conclusions cannot be extrapolated to other animal species/categories. The use of lactic acid and calcium lactate as feed additives is safe for the consumer. Lactic acid is considered an irritant to eyes and skin and there is a risk of serious damage to the eyes. Inhalation of the mist causes irritation of the respiratory system. Calcium lactate should be considered an irritant to skin, eyes and the respiratory tract. It is likely that handling the additive will result in the production of respirable dust, which could present a risk to unprotected workers. The use of lactic acid and calcium lactate in animal nutrition would not pose a risk to the environment, provided that the concentrations regarded as safe for the target species are not exceeded. Lactic acid and calcium lactate are used in food as preservatives. It is reasonable to expect that the effect seen in food will be observed in feed when these additives are used at comparable concentrations and under similar conditions. However, the Panel has reservations about the effectiveness of lactic acid and calcium lactate as preservatives in complete feedingstuffs with a typical moisture content of <= 12 %