The objective of the present study was to assess the association between the observed and perceived food environment and food insecurity among households with children <18 years in Lima, Peru. This was a cross-sectional study including an income-stratified random sample of households (n 329) in Villa el Salvador, a low-income district in Lima, Peru. Data were collected with a household questionnaire – including the Household Food Insecurity Access Scale (HFIAS) and the University of Pennsylvania's Perceived Nutrition Environment Survey (NEMS-P) – and a neighbourhood food outlet census, including recording of food outlets’ GPS coordinates. Three-quarters of the households interviewed were food insecure. Compared with food secure households and adjusting for socio-demographic covariates, food insecure households were more likely to disagree to having easy access (OR 5⋅4; 95 % CI 2⋅1, 13⋅4), high quality (OR 3⋅1; 95 % CI 1⋅7, 5⋅5) and variety (OR 2⋅5; 95 % CI 1⋅4, 4⋅6) of fresh fruits and vegetables in their neighbourhood. About 60 % (513 out of 861) of the food outlets identified in participants’ neighbourhoods were classified as fresh, including markets, bodegas, and fruit and vegetable vendors. There was no difference in distance to fresh food outlets by household food insecurity; all households were on average within 52–62 m from a fresh food outlet (~2-min walk). Despite negative perceptions of their neighbourhood food environment, food insecure households had similar physical access to fresh food sources than their food secure counterparts. Thus, changes to the food environment may not alleviate food insecurity in urban poor areas of Peru.

The PA6G blue is a polymeric material for great versatility of engineering applications that required good mechanical and tribological properties such as gears. The focus of this study was to investigate the mechanical properties as well as the friction and wear resistance of a commercial PA6G blue under biodegradable external lubrication, to evaluate its potential use for gear applications. Firstly, the PA6G blue was characterized by FTIR analysis in order to identify the characteristic chemical groups of this polymer. The mechanical characterization was performed by tension and hardness tests according to the standards ASTM D638 and ASTM E10, respectively. Subsequently, friction tests were carried out on a tribometer with pin-on-disk configuration based on the ASTM G99 standard, in dry and lubricated conditions. Natural castor and canola oils were employed as bio-lubricants, as well as their mixture at 50% by volume. The results exhibited that the PA6G blue exhibit good mechanical performance as that required by gear fabrications. Besides, the friction performance showed a low friction coefficient of 0.11 in the dry condition that decreased about 50% in lubricated tests, obtaining a friction coefficient value of 0.054.

Since ancient times, lubricants have been used to reduce friction and wear problems of mechanical systems. However, nowadays, there is a constant effort to improve their performance through additives so that they can accomplish properly in this modern world. In that sense, in this study, it was proposed the use of Poly(ε-Caprolactone) (PCL) as a biodegradable additive in Castor oil. The effect that this additive has on the tribological properties of AISI 4140 steel/Al2O3 tribosystem was analyzed. For this purpose, PCL was dissolved in Castor oil at 65 °C for 15 minutes. Later, once the lubricant formulations got into room temperature, friction tests were conducted with a ball-on-disk configuration. Several experiments were systematically carried out in order to study the factors that could influence the performance of the tribological system, for instance: additive concentration, velocity, temperature, and wear track radius. The kinetic friction coefficient was used to analyze the results as an output variable. The parameters in which the best friction behavior was observed were employed again to compare the efficiency of the polymeric additive by profoundly analyzing and comparing the wear response of the system. The PCL additive showed great results by decreasing friction up to 30% compared to the neat Castor oil. Nevertheless, as the opposite effect, this additive increased the steel wear to almost half an order of magnitude. Given the above, this investigation showed that, with further studies, Poly(ε-Caprolactone) could be used as an additive in vegetable oil-based lubricants for the improvement of friction performance.

The aim of this investigation was to study castor, canola, and sesame vegetable oils in order to evaluate their potential use as lubricants in steel mechanical components. For this purpose, densities of each oil were evaluated using the pycnometer method, as well as their dynamic viscosities through a Brookfield DV-II rotational viscometer. Both properties were evaluated at temperatures of 25, 40 and 100 °C. Additionally, viscosity indexes were determined according to ASTM D 2270. These rheological properties were used to estimate the lubrication regime considering parameters of real contact conditions in mechanical components. Friction and wear analyses were carried out to investigate the behaviour of the vegetable oil as lubricants. Such tests were carried out at room temperature on a CSM tribometer with pin-on-disk configuration by using castor, canola and sesame oils as lubricants. AISI 4140 hardened steel against AISI 100Cr6 steel pin was used as a mechanical component. From the rheological study, it was observed that canola and sesame oils behave as dilatant fluids at the evaluated temperatures, while castor oil behaves like a Newtonian fluid at 25 and 40 °C. Castor oil showed the highest density value among oils studied, but it also exhibited the lowest value of viscosity index (271). Contrarily, sesame oil was the least dense, but it exhibited the highest viscosity index (545). On the other hand, the lubrication regime study showed that by using castor oil as a lubricant in the mechanical component (4140/100Cr6), the system worked in a mixed lubrication regime while by using canola and sesame oils the system operated in boundary lubrication conditions. Finally, the kinetic friction coefficients were different for each lubricant obtaining the lowest value with castor oil while the highest value of friction coefficient was exhibited by the sesame oil lubricant.

The aim of this research was to investigate the influence of substrate roughness on the adhesion and tribological performance of thin TiN coatings obtained by physical vapor deposition. For that purpose, substrates of AISI H13 steel with surface finishes of 0.06, 0.28 and 0.90 μm in Ra were coated with TiN under the same coating conditions. The chemical composition of the steel, as well as that of the TiN coating, were obtained using EDS analysis. Adhesion tests were carried out following the procedure of BSi 1071-8 standard while hardness was evaluated by ASTM C 1327-03. On the other hand, dry sliding friction tests were conducted with a pin-on-disk tribometer, according to the ASTM G 99-05 standard. This study showed that the roughness of the coating increases as the substrate roughness increases. Regarding adhesion and hardness, all the samples showed an adhesion class 1 according to the standard and a hardness value of 14.51 GPa. Nevertheless, the highest substrate roughness produced the best adhesion. On the other hand, the lowest values for the friction coefficient and wear behavior were obtained by the sample with the lowest substrate roughness of 0.06 µm. In addition, it was found that friction and wear increase when the substrate roughness increases.

Poly (methyl methacrylate)/hydroxyapatite (PMMA/HAp) nanocomposites with HAp nanoparticles content of 12 wt.% were obtained by free-radical polymerization synthesis. Three different concentrations of benzoyl peroxide (PBO) of 3, 6, and 12 wt.% were studied. The results showed that the concentration of PBO has an effect on the performance of composites. In particular, the nanocomposite with the highest concentration of PBO presented the best mechanical and tribological behavior, as well as the lowest values of water absorption and porosity percent.

Species co-occurrence is an important ecological research area. Mark-and-recapture studies of mammals allow identification of coexisting species, a necessary step in determining mechanisms enabling habitat sharing. Using data from five 1-ha grids in January 2004 in tropical dry deciduous forest of coastal Colima, Mexico, we detected significantly more interspecific overlap than expected between seven species pairs. Oryzomys couesi shared more stations than expected with Sigmodon mascotensis, Baiomys musculus and Peromyscus perfulvus. Baiomys musculus was associated positively with S. mascotensis and Reithrodontomys fulvescens. Heteromys pictus shared fewer stations than expected with O. couesi and S. mascotensis. For species collectively, there was non-random community structuring, with two grids displaying more species aggregation than expected. While two grids had non-random co-occurrence patterns, three grids did not differ from random, which differs from that reported for mammalian taxa on average. Other small-mammal studies have documented species segregation, while this study detected more positive than negative associations. Similarities in preference and habitat use (or diet) are likely explanations for interspecific overlap patterns at stations and co-occurrence patterns among grids. Simultaneously evaluating associations of species pairs and all species on a grid collectively is novel methodology as applied to mammals, adding to understanding of species co-occurrence.

We assessed the in vitro antimicrobial activity and the in vivo efficacy of dipping ventricular assist devices in a combination of N-acetylcysteine, gentamicin, and amphotericin B (NAC/G/A). Ventricular assist devices dipped in NAC/G/A exhibited broad-spectrum antimicrobial activity in vitro and were less likely than undipped devices to become colonized with Staphylococcus aureus in a rabbit model.