Theory and data for simulating fine-scale human movement in an urban environment

Individual-based models of infectious disease transmission depend on accurate quantification of fine-scale patterns of human movement. Existing models of movement either pertain to overly coarse scales, simulate some aspects of movement but not others, or were designed specifically for populations in developed countries. Here, we propose a generalizable framework for simulating the locations that an individual visits, time allocation across those locations, and population-level variation therein. As a case study, we fit alternative models for each of five aspects of movement (number, distance from home and types of locations visited; frequency and duration of visits) to interview data from 157 residents of the city of Iquitos, Peru. Comparison of alternative models showed that location type and distance from home were significant determinants of the locations that individuals visited and how much time they spent there. We also found that for most locations, residents of two neighbourhoods displayed indistinguishable preferences for visiting locations at various distances, despite differing distributions of locations around those neighbourhoods. Finally, simulated patterns of time allocation matched the interview data in a number of ways, suggesting that our framework constitutes a sound basis for simulating fine-scale movement and for investigating factors that influence it.     

Apparatus Prototype for Purposes of Teaching in Bio-digesters

A mathematical model is developed based on a simplified mechanism of anaerobic digestion. The main objective is to quantitatively analyze the digestion process to optimize operating conditions and maintenance of this equipment, which could be used to test different materials and be able to apply these results to the possible scaling to bio-digesters installed in the field. The experiments were carried out in a hybrid system bio-digester photovoltaic cells. The bio-digester is made of stainless steel with dimensions to treat an average of 10 kg of raw material and produce biogas from different organic materials. The reactor has been conditioned with temperature sensors, pressure and methane gas that allow monitoring the concentration of the gas and the conditions of operation during the time of digestion. The system has a photovoltaic array to provide the energy required to keep the temperature constant, The experiment was conducted using materials such as goat manure mixed with household waste, and various formulations of these materials were prepared. The experimental results were used to test the mathematical model.     

Magnetoelectric Response in (1−x)PbZr0.65Ti0.35O3–xBaFe12O19 Multiferroic Ceramic Composites

The magnetoelectric (ME) properties of PbZr_0.65Ti_0.35O₃–BaFe₁₂O₁₉ (PZT–BaM) multiferroic ceramic composites have been investigated in this work. These materials, containing both the ferroelectric PZT and ferrimagnetic BaM phases, were prepared from the conventional solid‐state reaction method, and their main (micro)structural characteristics are provided. The ME measurements were performed over wide frequency and temperature ranges, and the influence of the BaM content was appraised. An enhanced ME coefficient (α) was obtained for the applied magnetic field of 0.8 kOe, at 97 kHz. In addition, the results reveal a high thermal stability of α in the whole analyzed temperature range, showing that the studied PZT‐based ceramic composites have great potential for practical applications.     

Identification of Novel CERT Ligands as Potential Ceramide Trafficking Inhibitors

A highly compartmentalized enzymatic network regulates the pro‐apoptotic and proliferative effects of sphingolipids. Over‐conversion of ceramide (Cer) correlates with insensitivity to apoptosis signaling (in response to chemotherapy) and to drug resistance of cancer cells. De novo sphingomyelin biosynthesis relies on non‐vesicular ceramide trafficking by the CERT (CERamide Transfer) protein. Therefore, blocking CERT transfer, thus leading to increased intracellular ceramide availability, represents a potential anticancer strategy. Our study is based on the implementation of an in vitro binding assay, supported by in silico molecular docking. It constitutes the first attempt to explore at the molecular level for the identification of novel CERT ligands. This approach is the first step toward in silico design and optimization of CERT inhibitor candidates, potentially relevant as innovative ceramide‐transfer‐targeting therapeutic agents.     

Impact of aliphatic amine comonomers on DGEBA epoxy network properties

This study characterized the mechanical and thermal properties of the oligomer‐based formulations of the diglycidyl ether of bisphenol A (DGEBA) cured with series aliphatic amines (triethylenetetramine (TETA), tetraethylenepentamine (TEPA) and O,O bis (2‐aminopropyl propylene glycol) (Jeffamine D230) with different functionalities in the glassy state. Impact Izod and three‐point bending tests were conducted to determine the networks' impact energy (E_i), elasticity modulus (E_y), yield stress (σ_y) and fracture toughness (K_IC) values. The same three‐point bending mode was also employed to characterize the systems' thermo‐mechanical properties (DMA) and storage modulus (E') and damping modulus (tan δ = E"/E') values. The DGEBA/D230 network showed greater flexibility, maximum impact energy, higher fracture toughness, and a lower yield stress than the DGEBA/TETA and DGEBA/TEPA networks. The fracture behavior of these epoxy systems was correlated to the molecular weight between the crosslink points, M_c, and the plastic zone size (r_p) at the crack tip carved in the samples. The DGEBA/D230 network had the highest storage modulus and tan δ intensity, together with higher toughness and deformation during the network's fracture. These results were a consequence of the structural characteristics of comonomers, including their chain segment flexibility, molecular weight between crosslink points and functionality. POLYM. ENG. SCI., 54:2132–2138, 2014. © 2013 Society of Plastics Engineers     

Dietary Lipid Intake only Partially Influences Variance in Serum Phospholipid Fatty Acid Composition in Adolescents: Impact of Other Dietary Factors

The present study aimed to assess the correlation between food and fatty acid (FA) intake and the serum phospholipid (PL) FA status in European adolescents and explored the percentage of variation in serum PL FA that could be attributed to dietary habits. Participants included 528 adolescents recruited in the HELENA Study. Dietary intake was assessed by two, self-administered, non-consecutive 24-h recalls. PL FA concentrations were measured in fasting venous serum samples. Reduced rank regressions were applied to examine the combined effect of food intakes. Results indicated that the variance in serum PL FA in adolescents, that could be explained by diet varied from 7.0 % for MUFA to 14.2 % for n-3FA. The variance in the long-chain n-3FA was mainly explained by fish intake but also by coffee and tea consumption. In conclusion this study indicated that dietary intake influences the serum PL FA status to a limited amount but that also other factors interfere. However, dietary intake is important as it is among those factors that could be modified. Furthermore, the results suggest that the overall dietary habits should be considered instead of only the consumption of single foods or nutrients, as the medium of the food or concomitant intake of foods and nutrients might interact and as such influence absorption or metabolism.     

Oxygen Reduction Reaction Promotes Li+ Desorption from Cathode Surface in Li‐O2 Batteries

Li‐O₂ batteries are claimed to be one of the future energy storage technologies. Great number of scientific and technological challenges should be solved first to transform Li‐O₂ battery from a promise to real practical devices. Proposed mechanisms for oxygen reduction assume a reservoir of solved Li⁺ ions in the electrolyte. However, the role that adsorbed Li⁺ on the electrode surface might have on the overall oxygen reduction reaction (ORR) has not deserved much attention. Adsorbed Li⁺ consumption is monitored here using impedance measurements from extended electrochemical double layer capacitance, which depends on the carbon matrix surface area. The presence of O₂ drastically reduces the amount of adsorbed Li⁺, signaling the kinetic competition between Li⁺ surface adsorption and its consumption, only for potentials corresponding to the oxygen reduction reaction. Noticeably double layer capacitance remains unaltered after cycling. This fact suggests that the ORR products (Li₂O₂ and Li₂CO₃) are not covering the internal electrode surface, but deposited on the outer electrode‐contact interface, hindering thereby the subsequent reaction. Current results show new insights into the discharge mechanism of Li‐O₂ batteries and reveal the evidence of Li⁺ desorption from the C surface when the ORR starts.     

Kinetics of the transformation of phenyl-urea herbicides during ozonation of natural waters: rate constants and model predictions

Oxidation of four phenyl-urea herbicides (isoproturon, chlortoluron, diuron, and linuron) was studied by ozone at pH=2, and by a combination of O3/H2O2 at pH=9. These experiments allowed the determination of the rate constants for their reactions with ozone and OH radicals. For reactions with ozone, the following rate constants were obtained: 1.9 +/- 0.2, 16.5 +/- 0.6, 393.5 +/- 8.4, and 2191 +/- 259 M(-1) s(-1) for linuron, diuron, chlortoluron, and isoproturon, respectively. The rate constants for the reaction with OH radicals were (7.9 +/- 0.1) x 10(9) M(-1) s(-1) for isoproturon, (6.9 +/- 0.2) x 10(9) M(-1) s(-1) for chlortoluron, (6.6 +/- 0.1) x 10(5) M(-1) s(-1) for diuron, and (5.9 +/- 0.1) x 10(9) M(-1) s(-1) for linuron. Furthermore, the simultaneous ozonation of these selected herbicides in some natural water systems (a commercial mineral water, a groundwater, and surface water from a reservoir) was studied. The influence of operating conditions (initial ozone dose, nature of herbicides, and type of water systems) on herbicide removal efficiency was established, and the parameter Rct (proposed by Elovitz, M.S., von Gunten, U., 1999. Hydroxyl radical/ozone ratios during ozonation processes. I. The Rct concept. Ozone Sci. Eng. 21, 239-260) was evaluated from simultaneous measurement of ozone and OH radicals. A kinetic model was proposed for the prediction of the elimination rate of herbicides in these natural waters, and application of this model revealed that experimental results and predicted values agreed fairly well. Finally, the partial contributions of direct ozone and radical pathways were evaluated, and the results showed that reaction with OH radicals was the major pathway for the oxidative transformation of diuron and linuron, even when conventional ozonation was applied, while for chlortoluron and isoproturon, direct ozonation was the major pathway.     

Synthesis of Structured Phosphatidylcholine Containing n-3 PUFA Residues via Acidolysis Mediated by Immobilized Phospholipase A<Subscript>1</Subscript>

Structured phosphatidylcholine (PC) was successfully synthesized by acidolysis of PC derived from soybean with n-3 polyunsaturated fatty acids (PUFA) obtained from fish oil using an immobilized phospholipase-A₁ from Thermomyces lanuginosus/Fusarium oxysporum as the biocatalyst. The effect of water activity in the range from 0.43 to 0.93 on n-3 PUFA residue content was investigated. The immobilized phospholipase was more active at water activities greater than 0.53. The yield of PC decreased as the water activity increased from 0.43 to 0.93. The yield of lysophosphatidylcholine (LPC) increased significantly during the first 4 h of reaction as a consequence of hydrolysis of the PC. As the enzyme loading increased, the proportion of n-3 PUFA residues in the PC and LPC present at various times in the mixture of these species increased to as much as 15% of the total weight of substrate. For all enzyme loadings tested, both the proportion of n-3 PUFA residues in the total PC (unreacted and modified) and the production of LPC increased significantly when the reaction time was increased, although differences in n-3 PUFA content were observed. When both the n-3 PUFA content of the PC and the total yield of PC are considered, the optimum water activity and enzyme loading for production of structured PC and LPC are 0.65 and 15%, respectively.