The optimum average nanopore size for hydrogen storage in carbon nanoporous materials

A thermodynamical model of hydrogen storage in slitpores is presented and applied to carbon and BN nanoporous materials. The model accounts for the quantum effects of the molecules in the confining potential of the slitpores. A feature of the model is a new equation of state (EOS) of hydrogen, valid over a range of pressures wider than any other known EOS, obtained using experimental data in the range 77-300 K and 0-1000 MPa, including data in the region of solid hydrogen. The model reproduces the experimental hydrogen storage properties of different samples of activated carbons and carbide-derived carbons at 77 and 298 K and at pressures between 0 and 20 MPa, for an average nanopore width of about 5 Å. The model predicts that in order to reach the US Department of Energy hydrogen storage targets for 2010, the nanopore widths should be equal to or larger than 5.6 Å for applications at low temperatures, 77 K, and any pressure, and about 6 Å for applications at 300 K and at least 10 MPa.     

GLP-1a: Going beyond Traditional Use

Glucagon-like peptide-1 (GLP-1) is a human incretin hormone derived from the proglucagon molecule. GLP-1 receptor agonists are frequently used to treat type 2 diabetes mellitus and obesity. However, the hormone affects the liver, pancreas, brain, fat cells, heart, and gastrointestinal tract. The objective of this study was to perform a systematic review on the use of GLP-1 other than in treating diabetes. PubMed, Cochrane, and Embase were searched, and the PRISMA guidelines were followed. Nineteen clinical studies were selected. The results showed that GLP-1 agonists can benefit defined off-medication motor scores in Parkinson’s Disease and improve emotional well-being. In Alzheimer’s disease, GLP-1 analogs can improve the brain’s glucose metabolism by improving glucose transport across the blood–brain barrier. In depression, the analogs can improve quality of life and depression scales. GLP-1 analogs can also have a role in treating chemical dependency, inhibiting dopaminergic release in the brain’s reward centers, decreasing withdrawal effects and relapses. These medications can also improve lipotoxicity by reducing visceral adiposity and decreasing liver fat deposition, reducing insulin resistance and the development of non-alcoholic fatty liver diseases. The adverse effects are primarily gastrointestinal. Therefore, GLP-1 analogs can benefit other conditions besides traditional diabetes and obesity uses.     

Use of Oxone® as a Potential Catalyst in Biodiesel Production from Palm Fatty Acid Distillate (PFAD)

Catalysis Letters - Palm fatty acid distillate PFAD is an example of potential low-cost palm biofuel second generation feedstock, most used as a source of fatty acid for non-food applications in...     

Synthesis and evaluation of compatibilizer based on interpenetrating polymer networks (IPN) for PET/LDPE blends

The present work considers the evaluation of recycled polymers, which are generally incompatible and are degraded during recycling with fatal consequences to their thermal and mechanical properties. Regarding this subject, the synthesis of a new compatibilizer in network form was carried out in order to counter such incompatibility. In this sense, low density polyethylene (LDPE) and poly(ethylene terephthalate) (PET) were compatibilized via the implementation of an interpenetrating polymer network (IPN), which was specifically synthesized to possess chemical groups that are akin to both plastics, PET and LDPE. The effects of the relative amount of poly(acrylic acid) (PAA) in the compatibilizer and the amount in the blends of PET/LDPE were evaluated. The results show that mechanical properties and interfacial adhesion of PET/LDPE blends were modified and improved with the addition of the synthesized compatibilizer compared with a commercial compatibilizer (polyethylene grafted with maleic anhydride, PE‐g‐AA). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43704.     

Drying behavior and decay resistance of rubberwood from steamed log and presteamed lumber

The objective of this study was to evaluate the effect of log steaming and steaming prior to drying singly and both treatments together on the drying behavior and decay resistance of Hevea brasiliensis wood (rubberwood). Logs with a diameter of 34.6?±?4.4?cm were used. Half of the logs were kept in their original condition, and the other half were steamed at 90°C for 36?h. Later, the logs were cut into flat sawn boards. Half of the boards were kept in their original condition, and the other half were presteamed at 90°C for 3?h after 1?h of heating-up. These boards were dried in a drying kiln. The drying defects, drying time, drying rate, and decay resistance of wood to the Pycnoporus sanguineus fungus were determined. The results showed that the steaming is not suitable for decreases in the time and the drying rates of this kind of wood, and it neither reduces the drying defects of boards. Furthermore, these treatments adversely affected the decay resistance of rubberwood to P. sanguineus fungi.     

Hydrothermal processing of rice husks: effects of severity on product distribution

BACKGROUND: Treatment in aqueous media (hydrothermal or autohydrolysis reactions) is an environmentally friendly technology for fractionating lignocellulosic materials. Rice husks were subjected to hydrothermal processing under a variety of operational conditions to cause the selective breakdown of xylan chains, in order to assess the effects of reaction severity on the distribution of reaction products. RESULTS: The effects of severity (measured by the severity factor, R₀) on the concentrations of the major autohydrolysis products (monosaccharides, xylo‐ and glucooligosaccharides, xylooligosaccharide substituents, acetic acid, acid‐soluble lignin and elemental nitrogen) were assessed. The interrelationship between the severity of treatment and molecular weight distribution was established by high‐performance size‐exclusion chromatography. Selected samples were subjected to refining treatments as ethyl acetate extraction and ion exchange for refining purposes, and the concentrates were assayed by high‐performance anion‐exchange chromatography and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. CONCLUSIONS The protein equivalent of the products present in liquors accounted for 43 to 51% of the protein present in the raw rice husks. The concentrations of glucose (derived from starchy material) and arabinose (split from the xylan backbone) were fairly constant with severity. Even in treatments at low severity, high molecular weight compounds derived from xylan accounted for a limited part of the stoichiometric amount. Operating under harsh conditions, about 50% of the total xylan‐derived compounds corresponded to fractions with a degree of polymerization (DP) < 9. After refining, saccharides accounted for more than 90% of the non‐volatile components of the sample. The refined products showed a series of xylose oligomers up to about DP 13, and a series of acetylated xylose oligomers up to about DP 15. Copyright © 2008 Society of Chemical Industry     

Microscopic characterisation of old mortars from the Santa Maria Church in Évora

Evora Cathedral (one of the most emblematic monuments of Evora — Portugal) has suffered several conservation and restoration interventions through the ages, without, however, any type of previous knowledge about mortars and materials used. This work was carried out in order to identify the mortar's composition in different locations, which were attributed to different construction or conservation periods.The characterisation methodology involved a multidisciplinary set of chemical, physical, microstructural and mechanical techniques, and gave special attention to the use of microstructural characterisation techniques, particularly petrographical analysis and scanning electron microscopy for the identification of the mortar's constituents as well as in the evaluation of the state of conservation.The test results showed that two types of aerial binders were used, dolomitic and calcitic limes, the former being predominant. The aggregates used have a siliceous nature and are similar in composition to the granodiorites of the region around Evora. The mortars differ in the aggregate contents and, in some cases, crushed bricks were used as an additive.     

Predicting the Behavior of an Earth and Rockfill Dam under Construction

This paper presents an application of a coupled hydromechanical formulation for compacted and rockfill materials to simulate the construction and impoundment of a zoned earth dam. The constitutive relation used to model the mechanical behavior of the shoulder, filter and core materials is the Barcelona Basic Model for unsaturated materials. The hydraulic behavior of dam materials requires the specification of their water retention characteristics and their permeabilities, which will be expressed as a function of porosity and degree of saturation. The model was used in the design stage of Lechago’s dam (Teruel, Spain), currently under construction. Soil parameters were obtained by laboratory tests performed on materials to be used in the dam. The step-by-step construction (following the sequence construction of nine horizontal layers, besides the downstream preloading layers) and subsequent impounding of the reservoir was simulated in a prediction exercise, which will be hopefully confronted with actual construction measurements in the near future. A parametric study was also performed to evaluate the effects of the compaction water content of the core material on the behavior of the dam.     

Test of a Method to Calculate Near-Bank Velocity and Boundary Shear Stress

Detailed knowledge of the flow and boundary shear stress fields near the banks of natural channels is essential for making accurate calculations of rates of near-bank sediment transport and geomorphic adjustment. This paper presents a high-resolution laboratory data set of velocity and boundary shear stress measurements and uses it to test a relatively simple, fully predictive, numerical method for determining these distributions across the cross-section of a straight channel. The measurements are made in a flume with a fairly complex cross-section that includes a simulated, cobble-roughened floodplain. The method tested is that reported by Kean and Smith in Riparian Vegetation and Fluvial Geomorphology in 2004, which is modified here to include the effects of drag on clasts located in the channel. The calculated patterns of velocity and boundary shear stress are shown to be in reasonable agreement with the measurements. The principal differences between the measured and calculated fields are the result of secondary circulations, which are not included in the calculation. Better agreement with the structure of the measured streamwise velocity field is obtained by distorting the calculated flow field with the measured secondary flow. Calculations for a variety of narrower and wider configurations of the original flume geometry are used to show how the width-to-depth ratio affects the distribution of velocity and boundary shear stress across the channel.