Wear tests on PTFE+pb linings for linear pneumatic actuator guide bushings

Guide bushings for linear actuators are subject to intense mechanical stress and wear, especially when external radial forces are applied. Carrying out simplified wear tests on the materials used in these bushings is important in making it possible to estimate how many cycles the actuator can perform before the bushing must be replaced. This paper presents the results of tribological pin-on-disk testing on an anti-friction lining consisting of a porous bronze sinter impregnated and coated with PTFE+Pb. Test specimens were worn with a steel ball, and wear and friction coefficients were determined experimentally with increasing loads and speeds

Scaffold Optimisation of Tetravalent Antagonists of the Mannose Binding Lectin

Antagonists of mannose binding lectin (MBL) have shown a protective role against brain reperfusion damage after acute ischemic stroke. Here we describe the design and streamlined synthesis of glycomimetic MBL antagonists based on a new tetravalent dendron scaffold. The dendron was developed by optimisation of a known polyester structure previously demonstrated to be very efficient for ligand presentation to MBL. Replacement of a labile succinyl ester bond with a more robust amide functionality, use of a longer and more hydrophilic linker, fast modular synthesis and orthogonal functionalisation at the focal point are the main features of the new scaffold. The glycoconjugate constructs become stable to silica gel chromatography and to water solutions at physiological pH, while preserving water solubility and activity in an SPR assay against the murine MBL-C isoform. Higher-order constructs were easily assembled, as demonstrated by the synthesis of a 16-valent dendrimer, which leads to two orders of magnitude increase in activity over the tetravalent version against MBL-C

Stimulation of Ca2+-ATPase Transport Activity by a Small-Molecule Drug

The sarco(endo)plasmic reticulum Ca(2+)−ATPase (SERCA) hydrolyzes ATP to transport Ca(2+) from the cytoplasm to the sarcoplasmic reticulum (SR) lumen, thereby inducing muscle relaxation. Dysfunctional SERCA has been related to various diseases. The identification of small‐molecule drugs that can activate SERCA may offer a therapeutic approach to treat pathologies connected with SERCA malfunction. Herein, we propose a method to study the mechanism of interaction between SERCA and novel SERCA activators, i. e. CDN1163, using a solid supported membrane (SSM) biosensing approach. Native SR vesicles or reconstituted proteoliposomes containing SERCA were adsorbed on the SSM and activated by ATP concentration jumps. We observed that CDN1163 reversibly interacts with SERCA and enhances ATP‐dependent Ca(2+) translocation. The concentration dependence of the CDN1163 effect provided an EC(50)=6.0±0.3 μM. CDN1163 was shown to act directly on SERCA and to exert its stimulatory effect under physiological Ca(2+) concentrations. These results suggest that CDN1163 interaction with SERCA can promote a protein conformational state that favors Ca(2+) release into the SR lumen

From optimized monovalent ligands to size-controlled dendrimers : an efficient strategy towards high-activity DC-SIGN antagonists

This short review describes our work on the development of dendrimeric antagonists of DC-SIGN, a dendritic cells (DCs) receptor recognizing highly mannosylated structures and primarily involved in the recognition of viruses such as HIV. The structure of pseudo-di-mannoside and pseudo-tri-mannoside compounds was first finely modified to obtain DC-SIGN ligands that were more stable and selective than mannose. Their DC-SIGN affinity differences were amplified once presented on multivalent dendrimer-like scaffolds, including poly-alkyne terminated and phenylene-ethynylene rod-like ones. Libraries of mannosylated dendrimers were synthesized, improving their stability and maximizing their monodispersity. The effect of the dendrimers valency, structure, and size on DC-SIGN affinity and antiviral potency was investigated. Both the valency and the topology of the architectures were revealed as key parameters for activity optimization, together with the intrinsic affinity of the monovalent ligand. The stability, rigidity, and length of the scaffolds were also tuned. The design of geometrically adapted scaffolds afforded one of the most potent inhibitors of DC-SIGN mediated HIV infections to date. This monodispersed, not cytotoxic, and highly active compound was also tested with DCs; its internalization into endolysosomal compartments and its ability to induce the overexpression of signaling molecules makes it a good precursor to produce pathogen-entry inhibitors with immunomodulant properties

Absolute frequency measurement of a Yb optical clock at the limit of the Cs fountain

We present the new absolute frequency measurement of ytterbium (171Yb) obtained at INRiM with the optical lattice clock IT-Yb1 against the cryogenic caesium (133Cs) fountain IT-CsF2, evaluated through a measurement campaign that lasted 14 months. Measurements are performed by either using a hydrogen maser as a transfer oscillator or by synthesizing a low-noise microwave for Cs interrogation using an optical frequency comb. The frequency of the 171Yb unperturbed clock transition ${^1}$S$_0\rightarrow {^3}$P0 results to be 518 295 836 590 863.44(14) Hz, with a total fractional uncertainty of $2.7 \times 10^{-16}$ that is limited by the uncertainty of IT-CsF2. Our measurement is in agreement with the Yb frequency recommended by the Consultative Committee for Time and Frequency. This result confirms the reliability of Yb as a secondary representation of the second and is relevant to the process of redefining the second in the International System of Units on an optical transition

Reproductive biology of spotted rose snapper Lutjanus guttatus (Teleostei: Lutjanidae) from Ensenada Búcaro, external border of Panama ecoregion

Se realizó un muestreo quincenal, por seis meses, de los desembarcos del pargo de la mancha (Lutjanus guttatus) en la comunidad de Búcaro, Panamá. Se recolectaron 237 individuos y se determinó sus variables morfométricas. Se seleccionaron 25 ejemplares para el análisis histológico de las gónadas. Se obtuvo un intervalo de talla entre 205 a 605 mm LT, y una proporción sexual que no difirió significativamente de la esperada 1M:1H. Se describen cuatro estadios de desarrollo gonadal en hembras y tres en machos. El índice gonadosomático y el factor de condición máximos en hembras fue de 1,67 en noviembre y de 1,24 en enero respectivamente, la talla de primera madurez sexual se estimó en 396,60 mm LT para hembras y 361,29 mm LT en machos. La información obtenida sugiere que la reproducción ocurre principalmente entre noviembre y enero.A biweekly sampling was carried out, for six months, of the landings of the spotted rose (Lutjanus guttatus) in the community of Búcaro, Panama. A total of 237 individuals was collected, and their morphometric variables were determined, 25 specimens were selected for the histological analysis of the gonads. A range of size 205 to 605 mm LT was obtained, the sex ratio was 1M: 1F. Four stages of gonadal development are described in females and three in males. Tre maximum values for the gonadosomatic index and the maximum condition factor in females were 1.67 in November and 1.24 in January respectively. The length at first sexual maturity was estimated at 396.60 mm LT for females and 361.29 mm LT for males. The information obtained suggests that reproduction occurs mainly between November and December. &nbsp

"Overarching sustainability objectives overcome incompatible directions in the Common Fisheries Policy"

The lack of clarity in the objectives of the Common Fisheries Policy (CFP) must be addressed to create a more efficient balance across diverse ecological, economic and social dimensions. Particularly economic and social objectives present at an overarching level must be made explicit and addressed in lower level management measures, in order to link them to biological objectives and allow policy to build a balance across types of objectives. Selecting clear objectives is essential, particularly for policy impact assessment. The aim of this paper is to demonstrate how more specific high level objectives to managing fisheries can be derived from stakeholders. The paper first reviews the definition of objectives, from a historical and conceptual perspective. Secondly, it discusses the issues of manageability and acceptability, and finally describes an articulation of the high level objectives derived from extensive stakeholder consultations at European and regional level. The results from workshops at the European level to identify objectives were further examined at regional level for the Baltic and North Seas in additional individual consultations. The German case addresses two seas (Baltic and North Seas), has a complex governance structure (due to federalism) and significant roles for the three types of actors (industry, government and environmental NGOs). The analysis suggests that establishing higher level sustainability objectives within the CFP can help diverse interest groups to develop a consensus on management actions to meet complex social goals

IMPACTO DEL COBRE (Cu) Y CADMIO (Cd) EN SEDIMENTO DEL ESTERO FARFÁN, GOLFO DE MONTIJO, PANAMÁ.

The levels of copper (Cu) and cadmium (Cd) were quantified in the sediments of the Farfán estuary, located in the Gulf of Montijo, Panama. Sediment samples were taken in six stations, with 2” diameter PVC nucleators, and salinity, temperature, dissolved oxygen, and pH of the water were measured with a multiparametric probe, monthly samplings, three months of the dry season, and three of the rainy seasons. The determination of copper and cadmium in the sediment samples were digested with nitric acid and read by atomic absorption spectrophotometry with a graphite furnace. The accumulation and ecological risk indices were calculated. Copper presented values between 5.1 and 151.5 µg / g, and cadmium varied between 0.01 and 0.18 µg / g. Significant differences (p = 0.0009) were observed between copper concentrations and the collection season and the relationship with medium sand and pH. The amount of cadmium showed no relationship with the variables studied, site, or sampling season. The values found were lower than those reported for the Panamanian Pacific.Se cuantificaron los niveles de cobre (Cu) y cadmio (Cd) en los sedimentos del estero Farfán, localizado en el golfo de Montijo, Panamá. Se tomaron muestras de sedimento en seis estaciones, con nucleadores de PVC de 2” de diámetro y se midieron salinidad, temperatura, oxígeno disuelto y pH del agua con una sonda multiparamétrica, muestreos mensuales, tres meses de temporada seca y tres lluviosa. La determinación de cobre y el cadmio en las muestras de sedimento fueron digestadas con ácido nítrico y leídas por espectrofotometría de absorción atómica con horno grafito. Se calcularon los índices de acumulación y de riesgo ecológico. El cobre presentó valores entre 5,1 y 151,5 µg/g, y el cadmio varió entre 0,01 y 0,18 µg/g. Se observaron diferencias significativas (p = 0,0009) entre las concentraciones de cobre y la temporada de colecta y relación con arena media y pH. La cantidad de cadmio no mostró relación con las variables estudiadas, sitio ni temporada de muestreo. Los valores encontrados fueron inferiores a los reportados para el Pacífico panameño

BIOMETRÍA Y DESARROLLO GONADAL DE LA CONCHA NEGRA Anadara tuberculosa EN EL ESTERO CATÉ, GOLFO DE MONTIJO

To find out the biometric relationships and gonadal development of the mangrove cockle Anadara tuberculosa, in Cate estuary, Gulf of Montijo, Panama, it was established six sampling stations collected manually each month from February to July 2017, the morphometrics characters were measured with a caliper and the weight with an analytic balance. The physicochemical properties were measured with a YSI multiparameter probe. The monthly growth was calculated by determining the length-frequency distribution and the modal analysis. A section of each gonad was extracted to determine the degree of maturity, based on a scale of four reproductive stages. The Sex Ratio was 1.06:1, the maximum spawning was in April coinciding with the maximum increase of salinity in the dry season. A. tuberculosa grew about 2.6 mm per month, the minimum length was 28.05 mm, and the highest 72.25, the weight varied between 10.5 to 126.2 g.Se determinó los aspectos biométricos, y el desarrollo gonadal de la concha negra Anadara tuberculosa en el estero Caté, localizado en el Golfo de Montijo, a los 7º 44’ 25” N y 81º 13’ 32” O. Se seleccionaron seis estaciones de muestreo, dos de ellas hacia los externos de la desembocadura. En cada sitio durante seis meses se tomaron muestras manualmente, se determinó la morfometría y el peso con ayuda de un vernier y una balanza analítica respectivamente.  El desplazamiento modal y la frecuencia de talla fueron estimados con histogramas. Cada gónada fue extraída para determinar el sexo y el grado de madurez, en base a cuatro etapas reproductivas. Se midieron los parámetros fisicoquímicos con una sonda multiparamétrica Marca YSI. A. tuberculosa creció 2,6 mm por mes; la talla máxima registrada fue de 72,25 mm y mínima de 28,05 mm. El mayor peso registrado fue de 126,2 g y el menor de 10,5 g. La proporción de sexos fue de 1,06:1 y el máximo desove se dio en el mes de abril, junto con el aumento de la salinidad en la temporada seca