ALBERT

Description: Oxygen mass transfer from air to the liquid phase in bioreactors with aerobic cultures has long been a serious impairment to the productivity of various bioprocesses. An increase of the oxygen mass transfer rate (OTR) can be the key to overcome oxygen limitation. The influence of higher air pressure on OTR was measured and a significantly enhanced OTR could be obtained. The oxygen volumetric mass transfer coefficient ( k L a ) was described by a function of the air pressure in a stirred lab-scale pressurized bioreactor. The correlation obtained proved that k L a slightly decreased with higher air pressure, following a power function. The oxygen mass transfer rate (OTR) and oxygen volumetric mass transfer coefficient ( k L a ) must be known to achieve optimum design operation and avoid oxygen transfer limitations. An increased air pressure is an important approach to enhance OTR and k L a . The proposed correlation could be valuable for further process optimizations where oxygen transfer is a limiting factor.

Description: Abstract An intercomparison of three regional climate models (PRECIS‐HadRM3P, RCA4, and RegCM4) was performed over the Coordinated Regional Dynamical Experiment (CORDEX) ‐ Central America, Caribbean and Mexico (CAM) domain to determine their ability to reproduce observed temperature and precipitation trends during 1980‐2010. Particular emphasis was given to the North American monsoon (NAM) and the mid‐summer drought (MSD) regions. The three RCMs show negative (positive) temperature (precipitation) biases over the mountains, where observations have more problems due to poor data coverage. Observations from the Climate Research Unit (CRU) and ERA‐Interim show a generalized warming over the domain. The most significant warming trend (≥ 0.34°C decade‐1) is observed in the NAM, which is moderately captured by the three RCMs, but with less intensity; each decade from 1970 to 2016 has become warmer than the previous ones, especially during the summer (mean and extremes); this warming appears partially related to the positive Atlantic Multidecadal Oscillation (+AMO). CRU, GPCP and CHIRPS show significant decreases of precipitation (less than ‐15% decade‐1) in parts of the Southwest United States and Northwestern Mexico, including the NAM, and a positive trend (5% to 10% decade‐1) in June‐September in eastern Mexico, the MSD region, and northern South America, but longer trends (1950‐2017) are not statistically significant. RCMs are able to moderately simulate some of the recent trends, especially in winter. In spite of their mean biases, the RCMs are able to adequately simulate interannual and seasonal variations. Wet (warm) periods in regions affected by the MSD are significantly correlated with the +AMO and La Niña events (+AMO and El Niño). Summer precipitation trends from GPCP show opposite signs to those of CRU and CHIRPS over the Mexican coasts of the southern Gulf of Mexico, the Yucatan Peninsula, and Cuba, possibly due to data limitations and differences in grid resolutions. This article is protected by copyright. All rights reserved.

Description: ABSTRACT The output of four regional climate models (RCMs) from the Coordinated Regional Climate Downscaling Experiment (CORDEX)-North America (NA) region was analysed for the 1990–2008 period, with particular interest on the mechanisms associated with wet and dry years over the North American Monsoon (NAM) core region. All RCMs (RCA3.5, HadGEM3-RA, REMO, and RegCM4) were forced by the ERA-Interim reanalysis. Model precipitation was compared against several observational gridded data sets at different time scales. Most RCMs capture well the annual cycle of precipitation and outperform ERA-Interim, which is drier than the observations. RCMs underestimate (overestimate) the precipitation over the coastal plains (mountains) and have some problems to reproduce the interannual variability of the monsoon. To further investigate this, two extreme summers that showed the largest consistency among observations and RCMs were chosen: one wet (1990) and one dry (2005). The impact of the passage of tropical cyclones, the size of the Western Hemisphere Warm Pool (WHWP), the Intertropical Convergence Zone (ITCZ) position, and the initial intensity of the land–sea thermal contrast (LSTC) were analysed. During the wet year, the LSTC was stronger than the 2005 dry monsoon season and there were a larger number of hurricanes near the Gulf of California, the WHWP was more extended, and the ITCZ was located in a more northerly position than in 2005. All these processes contributed to a wetter NAM season. During the dry year, the LSTC was weaker, with a later onset, probably due to a previous very wet winter. The inverse precipitation relationship between winter and summer in the monsoon region was well captured by most of the RCMs. RegCM4 showed the largest biases and HadGEM3-RA the smallest ones.

Description: The search for new adsorbents with enhanced capacity and selectivity, suitable for application on large-scale simulated moving-bed units for separation of p- xylene, requires efficient, reliable, and fast adsorbent characterization methods for this specific separation. Fixed-bed experiments were carried out under the conditions of the Parex process to evaluate a faujasite-type zeolite as adsorbent for the separation of p- xylene from its isomers in the proportions of the real Parex feed stream. The experimental breakthrough curves were used to evaluate the selected adsorbent in terms of nonselective and selective volumes, adsorption capacity, selectivity, and productivity, which can be applied to identify the feasible separation region for different operating conditions. A method based on experimental breakthrough curves for quickly evaluating adsorbents for a defined separation in terms of selective volume, capacity, selectivity and productivity is demonstrated under the conditions of the Parex process. Fixed-bed experiments are carried out in order to assess a barium-exchanged faujasite-type zeolite as adsorbent for the separation of p- xylene from its isomers.

Description: The main purpose of this pilot study was to investigate the possible influence of genetic polymorphisms of the hOGG1 (Ser326Cys) gene in DNA damage and repair activity by 8-oxoguanine DNA glycosylase 1 (OGG1 enzyme) in response to 16 weeks of combined physical exercise training. Thirty-two healthy Caucasian men (40–74 years old) were enrolled in this study. All the subjects were submitted to a training of 16 weeks of combined physical exercise. The subjects with Ser/Ser genotype were considered as wild-type group (WTG), and Ser/Cys and Cys/Cys genotype were analysed together as mutant group (MG). We used comet assay in conjunction with formamidopyrimidine DNA glycoslyase (FPG) to analyse both strand breaks and FPG-sensitive sites. DNA repair activity were also analysed with the comet assay technique. Our results showed no differences between DNA damage (both strand breaks and FPG-sensitive sites) and repair activity (OGG1) between genotype groups (in the pre-training condition). Regarding the possible influence of genotype in the response to 16 weeks of physical exercise training, the results revealed a decrease in DNA strand breaks in both groups, a decrease in FPG-sensitive sites and an increase in total antioxidant capacity in the WTG, but no changes were found in MG. No significant changes in DNA repair activity was observed in both genotype groups with physical exercise training. This preliminary study suggests the possibility of different responses in DNA damage to the physical exercise training, considering the hOGG1 Ser326Cys polymorphism. Copyright © 2015 John Wiley & Sons, Ltd.

Description: Morphology, etching patterns, surface modification, and characterization of 2 different fiber posts: Gfp, Glass fiber post; and Cfp, carbon fiber were investigated by SEM analysis, after different surface treatments. Thirty fiber posts, being 15 Gfp and 15 Cfp were divided into a 5 surface treatments ( n = 3): C-alcohol 70% (control); HF 4%-immersion in 4% hydrofluoric acid for 1min; H 3 PO 4 37%-immersion in 37% phosphoric acid for 30s; H 2 O 2 10%-immersion in 10% hydrogen peroxide for 20 min; H 2 O 2 24%-immersion in 24% hydrogen peroxide for 10 min. Morphology, etching patterns, surface modification and surface characterization were acessed by SEM analysis. SEM evaluation revealed that the post surface morphology was modified following all treatment when compared with a control group, for both type of reinforced posts. HF seems to penetrate around the fibers of Gfp and promoted surface alterations. The Cfp surface seems to be inert to treatment with HF 4%. Dissolution of epoxy resin and exposure of the superficial fiber was observed in both post groups, regardless the type of reinforcing fiber, H 2 O 2 in both concentrations. Relative smooth surface area was produced by H 3 PO 4 37% treatment, but with similar features to untreated group. Surface treatment of fiber post is a determinant factor on micromechanical entanglement to resin composite core. Post treatment with hydrogen peroxide resulted strength of carbon and glass/epoxy resin fiber posts to resin composite core. Microsc. Res. Tech., 2011. © 2011 Wiley-Liss, Inc.

Description: The temporal variability in nitrogen (N) transport in the Corbeira agroforestry catchment (NW Spain) was analyzed from October 2004 to September 2008. Nitrate (NO 3 -N) and total Kjeldahl nitrogen (TKN) loads and concentrations were determined at various time scales (annual, seasonal and event). The results revealed a strong intra- and inter-annual variability in N transport influenced by weather patterns, and consequently by the hydrological regime. Mean annual export of total N in the catchment was 5.5 kg ha -1  yr -1 , with NO 3 -N being the dominant form. Runoff events comprised 10% of the study period, but contributed 40% and 61% of the total NO 3 -N and TKN loads, respectively. The NO 3 -N and TKN concentrations were higher during runoff events than under baseflow conditions, pointing to diffuse sources of N. The mobilization of TKN during runoff events was attributed to surface runoff, while NO 3 -N might be related to subsurface and groundwater flow. Runoff events were characterized by high variability in N loads and concentrations. Higher variability was observed in N loads than in N concentrations, indicating that event magnitude plays an important role in N transport in this catchment; event magnitude explained approximately 96% of the NO 3 -N load. However, a combination of variables related to runoff-event intensity (rainfall, discharge increase and kinetic energy) explained only 66% of the TKN load. This article is protected by copyright. All rights reserved.

Description: The adsorption of the main components of the Parex process, i.e., p -xylene, m -xylene, o -xylene, ethylbenzene, p -diethylbenzene, and toluene, was studied in a batch adsorber operating under the conditions of an industrial unit (177 °C, 9 bar). Prior to each experiment, the faujasitic-type adsorbent was pretreated under helium flow to control the hydration level of the adsorbent. The experimental uptake curves were used to determine adsorption equilibrium data, which were fitted with Langmuir-type isotherms. A mathematical model in which the macropore diffusion is the rate-controlling mechanism, satisfactorily describes the experimental uptake curves. The Parex process, used for the separation of p -xylene is based on the affinity differences to the adsorbent between p -xylene and the other components of the feed. The adsorption of these components is studied under industrial conditions using experimental uptake curves obtained from batch experiments and mathematical modeling with the macropore diffusion rate as the rate-controlling mechanism.

Description: Abstract Aim This study aims to evaluate phylogenetic structure of turtle communities and their potential correlates on a global scale. More specifically, we tested whether cold temperatures and low precipitation could act as potential environmental filters of turtle communities and whether the dispersal limitation caused by altitudinal range could generate phylogenetic clustered patterns in these communities. Location Global. Taxon Turtles. Methods We used phylogenetic and distributional data of 257 species of turtles on a grid of 100 km × 100 km to generate measures of phylogenetic structure (mean nearest taxon distance and the mean pairwise distance, and their standardized effect sizes—SES) of turtle communities using three different species pools. We evaluated the relationship between SESs with climatic and altitudinal data in order to evaluate our hypotheses. Finally, we inspected whether there was phylogenetic signal in the climatic variables classified as potential filters, as it is a basic assumption for using phylogenetic structure metrics to infer assembly rules. Results Phylogenetic clustering was generally stronger than phylogenetic overdispersion in turtle communities. There was a positive relationship between minimum temperature and the phylogenetic structure metrics, while minimum precipitation and altitudinal range were negatively related to these metrics. We found a strong phylogenetic signal in the minimum temperature, while precipitation had a weak signal. Main conclusions The positive correlation between phylogenetic community structure metrics and minimum temperature and the phylogenetic signal present in this climatic variable are in accordance with our initial hypothesis regarding minimum temperature acting as an environmental filter for turtles. However, we did not find evidence to support minimum precipitation as a filter. Altitudinal range followed the expected patterns, suggesting that it increases dispersal limitation and allows a concentration of closely related species.