Dry sliding friction and wear response of WC-Co hardmetal pairs in linearly reciprocating and rotating contact

This paper presents an experimental evaluation of friction and wear properties of WC-Co cemented carbides. A comparison is made between unlubricated rotating and linearly reciprocating pin-onplate sliding pairs. The plate specimens were WC-10wt%Co grades surface finished by polishing or sequential wire-EDM steps, whereas WC-6wt%Co pins were used as counter body. The tests were carried out at room temperature using a sliding speed of 0.30m/s and mean Hertzain contact pressures of 1.76 and 2.08 GPa, i.e., normal contact loads of 15N and 25N, respectively. The worn surfaces on plate samples were quantified in terms of 2–D wear profiles obtained by means of surface topography scanning equipment. Wear mechanisms such as polishing and abrasion were identified using optical microscopy. Inferior tribological characteristics for wire-EDM surface finish compared to polishing were found. Higher friction coefficient and wear levels were measured in unidirectional rotating sliding experiments compared to linearly reciprocating test conditions

Aproximaciones a la valoración económica de productos no maderables del Bosque Atlántico del Alto Paraná, Paraguay

Corresponding author: Natalia Carolina Peralta Kulik; [email protected]: The economic valuation of ecosystem services provided by forests is a necessary effort for the sustainable management of forest ecosystems. Objective: Estimating the economic direct use value expressed by non-timber forest products (NTFPs) of the Alto Paraná Atlantic forests, Paraguay. Materials and methods: The study was carried out in a 1-ha permanent monitoring plot and the direct market price method was used. Non-timber species were identified and classified according to their uses, they were prioritized according to commercial importance and national market reference prices were applied. Results and discussion: A total of 36 species with potential non-timber uses (medicinal, ornamental, food and handicraft) were identified, among which the following were prioritized: Didymochlaena truncatula (Sw.) J. Sm., Miltonia sp., Oeceoclades maculata (Lindl.) Lindl., Thaumatophyllum bipinnatifidum (Schott. ex Endl.) Sakur., Calazans & Mayo, Billbergia nutans H. Wendl. ex Regel, Acianthera sp. and Chusquea ramosissima Lindm. The medicinal category was the strongest category (71 %). The economic value of the prioritized NTFPs with ornamental uses and market prices per unit was 2 270 USD∙ha-1. Conclusions: The economic value of NTFPs from the Alto Paraná Atlantic forests represents a reference value indicating the important role of non-timber products in the sustainable management of tropical forests.Introducción: La valoración económica de los servicios ecosistémicos que brindan los bosques es un esfuerzo necesario para el manejo sostenible de los ecosistemas forestales. Objetivo: Estimar el valor económico de uso directo expresado a través de los productos forestales no maderables (PFNM) del Bosque Atlántico del Alto Paraná, Paraguay. Materiales y métodos: El estudio se llevó a cabo en una parcela permanente de monitoreo de 1 ha y se utilizó el método directo de precios de mercado. Las especies no maderables se identificaron y se clasificaron de acuerdo con sus usos, se priorizaron según su importancia comercial y se aplicaron precios referenciales del mercado nacional. Resultados y discusión: Se identificaron 36 especies con posibles usos no maderables (medicinal, ornamental, alimenticio y artesanal), entre las cuales se priorizaron: Didymochlaena truncatula (Sw.) J. Sm., Miltonia sp., Oeceoclades maculata (Lindl.) Lindl., Thaumatophyllum bipinnatifidum (Schott. ex Endl.) Sakur., Calazans & Mayo, Billbergia nutans H. Wendl. ex Regel, Acianthera sp. y Chusquea ramosissima Lindm. La categoría medicinal fue la mejor representada (71 %). El valor económico de los PFNM priorizados con usos ornamentales y precios de mercado por unidad fue 2 270 USD∙ha-1. Conclusiones: El valor económico de los PFNM del Bosque Atlántico del Alto Paraná constituye un monto de referencia que representa el rol importante de los productos no maderables en el manejo sustentable de los bosques tropicales.Consejo Nacional de Ciencia y TecnologíaPrograma Paraguayo para el Desarrollo de la Ciencia y Tecnología. Programa Nacional de Incentivo a los Investigadore

A review on water lubrication of polymers

Water lubrication for polymers which is an economical solution has not been completelyreviewed from the qualitative perspective. A comparative study on water lubrication of polymers helpsto understand the fundamental aspects of tribology relevant to the different applications. The use ofwater as a lubricating material has been effective after the development of phenolic resins, further towhich the advancements in thermoplastics has increased the water lubrication to a greater extent.Most of the researches on water lubrication of polymers reported a positive frictional character anduncertain wear behavior on comparing with air and oil lubrication. From the existing literature inpolymer tribology with different parameters such as contact pressure, velocity and composition ofmaterials there is a lack of knowledge in understanding the mechanism involved during the wearprocess for water lubrication. Moreover, connection between the mechanical properties of polymerunder wet condition relating to the water lubricated polymers could give appropriate results oftribological behavior. Exploring the tribo-mechanical characteristic in wet condition aids to chooseappropriate material for water lubricated applications

Identification of Amino Acid Residues Responsible for Inhibition of Host Gene Expression by Influenza A H9N2 NS1 Targeting of CPSF30

H9N2 influenza A viruses (IAV) are considered low pathogenic avian influenza viruses (LPAIV). These viruses are endemic in poultry in many countries in Asia, the Middle East and parts of Africa. Several cases of H9N2-associated infections in humans as well as in pigs have led the World Health Organization (WHO) to include these viruses among those with pandemic potential. To date, the processes and mechanisms associated with H9N2 IAV adaptation to mammals are poorly understood. The non-structural protein 1 (NS1) from IAV is a virulence factor that counteracts the innate immune responses. Here, we evaluated the ability of the NS1 protein from A/quail/Hong Kong/G1/97 (HK/97) H9N2 to inhibit host immune responses. We found that HK/97 NS1 protein counteracted interferon (IFN) responses but was not able to inhibit host gene expression in human or avian cells. In contrast, the NS1 protein from earlier H9N2 IAV strains, including the first H9N2 A/turkey/Wisconsin/1/1966 (WI/66), were able to inhibit both IFN and host gene expression. Using chimeric constructs between WI/66 and HK/97 NS1 proteins, we identified the region and amino acid residues involved in inhibition of host gene expression. Amino acid substitutions L103F, I106M, P114S, G125D and N139D in HK/97 NS1 resulted in binding to the 30-kDa subunit of the cleavage and polyadenylation specificity factor (CPSF30) and, in consequence, inhibition of host gene expression. Notably, changes in the same amino acid residues resulted in the lack of inhibition of host gene expression by WI/66 NS1. Importantly, our results identified a new combination of amino acids required for NS1 binding to CPSF30 and inhibition of host gene expression. These results also confirm previous studies demonstrating strain specific differences in the ability of NS1 proteins to inhibit host gene expression

On-line and post-mortem wear measurement of static counterpart in a ball-on-disk test

this paper presents an experimental evaluation of friction coefficient and wear of WC binderlessceramics. The tests were conducted at room temperature and atmospheric conditions according to theASTM G99-95a standard. Silicon carbide (SiC) balls were used as static counterpart. The tests wereperformed at a rotating sliding speed of 0.3 m/s and an initial mean Hertzian contact pressure of 1.9 GPa.The disk specimens were surface finished by grinding. On-line monitoring and post-mortem analysis withtwo independent techniques, i.e., surface profilometry and optical microscopy, were used to elucidate thetribological characteristics of the studied material. Results of the post-mortem measurements werecompared to a geometrical wear model for calculation of the volume of the worn cap of the ball. Thiscalculation appeared to be in good agreement with the on-line wear monitoring. The first 100 m of slidingwas identified as running-in period. Beyond a sliding distance of 100 m a steady stage in penetration depthwas reached, while a higher fluctuation in friction coefficient was observed, which could be attributed to theinteraction with wear particles and simultaneous formation and delamination of debris layer, polishing andabrasion

Abundance and trait-matching both shape interaction frequencies between plants and birds in seed-dispersal networks

Abundance and trait-driven processes have both been identified as potential mechanisms in determining the occurrence of species interactions. However, little is known about how these two mechanisms interact to determine the relative frequencies of interactions between species, and thereby species-specific contributions to ecological functions. Here, we evaluate the effect of both species’ abundance and trait-matching on the occurrence of plant-bird seed dispersal interactions in the Cantabrian Range (northern Spain). For two years at fourteen plots, we independently sampled the abundance and diversity of fleshy-fruited plants and frugivores, as well as the consumption of fruits by birds. We quantified trait-matching by applying a food-web approach based on the log-ratios of species traits relevant to seed dispersal and traits related to fruit-handling and foraging-stratum. We fitted multi-level models incorporating phylogenetic relatedness to identify phylogenetically independent effects of species abundance and traitmatching on interaction frequencies. Fitted models showed that species abundances of both plants and birds always had strong positive effects on interaction frequencies. Trait-matching effects associated with fruit-handling were weak, but consistent across years, whereas those derived from foraging stratum varied across years, according to strong interannual changes in species abundance. Our findings reveal that both species abundance and functional traits are required for a mechanistic understanding of species interactions, as well as for predicting species roles in ecosystems under global change.MinECo/ FEDER grants, an Alumni- Grant from Senckenberg University, the Balearic Government., BIOINTFOREST funded by “Obra Social la Caixa” and “Fundaci on Caja Navarra”, under the agreement LCF/PR/ PR13/51080004 in the framework of UPNA’s “Captaci on de Talento” program.http://www.elsevier.com/journals/basic-and-applied-ecology/1439-1791am2024Mammal Research InstituteZoology and EntomologySDG-15:Life on lan

Blood stasis imaging predicts cerebral microembolism during acute myocardial infarction

Background: Cardioembolic stroke is a major source of mortality and disability worldwide. The authors hypothesized that quantitative characterization of intracardiac blood stasis may be useful to determine cardioembolic risk in order to personalize anticoagulation therapy. The aim of this study was to assess the relationship between image-based metrics of blood stasis in the left ventricle and brain microembolism, a surrogate marker of cardiac embolism, in a controlled animal experimental model of acute myocardial infarction (AMI). -- Methods: Intraventricular blood stasis maps were derived from conventional color Doppler echocardiography in 10 pigs during anterior AMI induced by sequential ligation of the mid and proximal left anterior descending coronary artery (AMI-1 and AMI-2 phases). From these maps, indices of global and local blood stasis were calculated, such as the average residence time and the size and ratio of contact with the endocardium of blood regions with long residence times. The incidence of brain microemboli (high-intensity transient signals [HITS]) was monitored using carotid Doppler ultrasound. -- Results: HITS were detected in 0%, 50%, and 90% of the animals at baseline and during AMI-1 and AMI-2 phases, respectively. The average residence time of blood in the left ventricle increased in parallel. The residence time performed well to predict microemboli (C-index = 0.89, 95% CI, 0.75–1.00) and closely correlated with the number of HITS (R = 0.87, P < .001). Multivariate and mediation analyses demonstrated that the number of HITS during AMI phases was best explained by stasis. Among conventional echocardiographic variables, only apical wall motion score weakly correlated with the number of HITS (R = 0.3, P = .04). Mural thrombosis in the left ventricle was ruled out in all animals. -- Conclusions: The degree of stasis of blood in the left ventricle caused by AMI is closely related to the incidence of brain microembolism. Therefore, stasis imaging is a promising tool for a patient-specific assessment of cardioembolic risk.This study was supported by grant PI15/02211, Rio Hortega (CM17/00144), and Juan Rodés fellowships (JR15/00039) from Instituto de Salud Carlos III; grant DPI2016-75706-P and a Juan de la Cierva fellowship (IJCI-2014-19507) from Ministerio de Economía y Competitividad; synergy grant Y2018/BIO-4858-PREFI-CM from Comunidad Autónoma de Madrid; the European Union - European Regional Development Fund; by the Spanish Society of Cardiology (ISBI-DCM); by the University of California,San Diego, CTRI Galvanizing Engineering and Medicine Program; American Heart Association grant 16GRNT27250262; and National Institutes of Health UC CAI grant CII4560. P.M.-L. was also funded by CIBERCV. P.M.-L., L.R., J.C.A., and J.B. are inventors of a method for quantifying intracardiac stasis from imaging data under a Patent Cooperation Treaty patent application (WO2017091746A1)