Development of composites based on recycled polyethylene/sugarcane bagasse fibers

In this work, sugarcane bagasse fibers were used as filler in composites having recycled high‐density polyethylene (PEr) as matrix. Because of the poor interaction between fibers surface and the PEr, the surface of bagasse was chemically modified. This modification consists of washing with water at 80°C, a mercerization process using sodium hydroxide and acetylation reaction with acetic anhydride. The chemical modification was characterized by Fourier transform infrared–horizontal attenuated total reflectance (FTIR‐HATR) and ¹³C nuclear magnetic resonance spectroscopies (NMR), thermogravimetric analysis (TGA), and scanning electronic microscopy (SEM). The composites were prepared from modified and unmodified fibers into PEr matrix, containing 5, 10, and 20% (w/w) of fiber. The samples were processed by extrusion and molds were prepared by injection process in order to perform mechanical tests. These materials were analyzed by SEM, TGA, and the water uptake was evaluated. Also, their mechanical properties were analyzed. Morphological analysis indicated that the chemical modification of sugarcane bagasse increased the compatibility between matrix and reinforcement. Tensile, flexural, and impact tests showed that the mechanical properties of the composite were improved compared to PEr due to the presence of the fibers. POLYM. COMPOS., 35:768–774, 2014. © 2013 Society of Plastics Engineers     

Determination of Ca,Cd, Cu,Fe, K,Mg, Mn,Mo, Na,Se, and Zn in Foodstuffs by Atomic Spectrometry After Sample Preparation Using a Low-Cost Closed-Vessel Conductively Heated Digestion System

Establishing fast, simple, low-cost, and efficient sample preparation procedures to determine elements in foodstuffs is a relevant aspect for nutritional and health purposes. For this reason, the recently proposed closed-vessel conductively heated digestion system (CHDS) was evaluated for the digestion of milk powder, chocolate powder, and soluble coffee samples aiming for Ca, Cu, Fe, K, Mg, Mn, Na, and Zn determinations by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS) and Cd, Mo, and Se determinations by inductively coupled plasma mass spectrometry with tandem configuration (ICP-MS/MS). The accuracy was evaluated by analyzing two milk certified reference materials digested by the CHDS and a microwave oven for comparison. When using the CHDS, recoveries for the analytes varied from 91 to 104 %. For microwave digestions, recoveries within the 94–109 % intervals were obtained. The method was then applied to the samples. For comparative purposes, the analytes were also determined in the samples after microwave digestion, and the results between the two digestion systems showed no differences based on a paired t test at a 95 % confidence level. Similar analytical blanks were obtained because quartz digestion tubes were used in both digestion systems. The CHDS with quartz tubes is an interesting alternative for laboratories dedicated to large-scale routine analysis because volatile elements usually found in very low concentrations in food samples such as Cd and Se can also be determined.     

Hot turning of a difficult-to-machine steel (sae xev-f) aided by infrared radiation

This paper discusses how to improve the position precision of a semi-closed loop servo system. A support vector regression algorithm is chosen to model and predict position error. The predicted error is then fed back to the input entry to compensate the error. Fuzzy PID control is introduced to adjust the controlling rule of the PID controller in the semi-closed loop servo system so as to improve the dynamic response characteristics of the servo system and reach a high degree of position precision. A case study is implemented. The simulation and experimental results show that combining the improved fuzzy control with predicted position error feedback ensures a high degree of position precision and a high degree of dynamic response characteristics.     

Recovery of carbon dioxide from sugarcane fermentation broth in the ethanol industry

Ethanol is one alternative to the use of petroleum-based fuels. It is produced on a large scale in Brazil from sugarcane to the magnitude of billions of liters per year. During the ethanol production step, a considerable amount of byproducts is obtained and treated as waste. Carbon dioxide is one of these byproducts and a substance of interest especially for food industries. Because the production of 1000 kg of ethanol generates approximately 950 kg of CO₂, this work intends to analyze a cryogenic distillation process for the production of CO₂ by means of computational simulations. The results obtained were in agreement with real operational conditions, achieving CO₂ concentrations up to 100% (v/v). With an initial CO₂ concentration of 95% (v/v), 7 separation stages were obtained, achieving the limit of 5 stages for higher CO₂ concentrations in the raw gas. The effect of initial CO₂ concentrations on the final product and the concentration profiles along the column are also presented. In order to optimize the process, it was observed that, for a maximum feed flow of 3333 kg/h (CO₂ concentration of 99%), the plant was able to obtain 10.48 kgCO₂/kW, recovering about 2828 kgCO₂/h at a final product concentration of 99.90% (v/v) at ?25 °C.     

Thermodynamic assessment of hydrogen production and cobalt oxidation susceptibility under ethanol reforming conditions

A comparative thermodynamic analysis of ethanol reforming reactions was conducted using an in-house code. Equilibrium compositions were estimated using the Lagrange multipliers method, which generated systems of non-linear algebraic equations, solved numerically. Effects of temperature, pressure and steam to ethanol, O₂ to ethanol and CO₂ to ethanol ratios on the equilibrium compositions were evaluated. The validation was done by comparing these data with experimental literature. The results of this work proved to be useful to foresee whether the experimental results follow the stoichiometry of the reactions involved in each process. Mole fractions of H₂ and CO₂ proved to be the most reliable variables to make this type of validation. Maximization of H₂ mole fraction was attained between 773 and 873 K, but maximum net mole production of H₂ was only achieved at higher temperatures (>1123 K). This work also advances in the thermodynamics of solid-gas phase interactions. A solid phase thermodynamic analysis was performed to confirm that Co⁰ formation from CoO is spontaneous under steam reforming conditions. The results showed that this reduction process occurs only for temperatures higher than 430 K. It was also found that once reduced, Co based catalysts will never oxidize back to Co₃O₄.     

The ITU-T Software Tool Library

The advancement of speech coding technology has led to new and improved standards. The Telecommunication Standardization Sector of the International Telecommunication Union (ITU-T) has been a leader in developing speech coding standards for telecommunications applications. To increase the efficiency of the coding standard selection process, a group called User's Group on Software Tools (UGST) was established in 1990 to produce a framework of speech coding-related software tools that would allow a common ground for activities across different organizations. Over the years, this group produced a high-quality software tool library (STL), which has been used in the definition of ITU and non-ITU standards, such as G.723.1, G.729, half-rate and enhanced full-rate GSM, among others. However, despite its usefulness, the ITU-T STL is largely unknown outside the telecommunications standards community. This paper introduces the ITU-T STL concepts and functionalities to the wider communications community.     

Effect of surface treatments based on self‐assembling molecules and cerium coatings on the AA3003 alloy corrosion resistance

This work presents the effects of a cerium conversion coating, self‐assembling molecules (SAM) treatment, and a combination of these two treatments on the corrosion resistance of the AA3003 alloy. The results were compared to that of a conversion coating treatment with hexavalent chromium (Cr VI). The corrosion resistance of the surface‐treated AA3003 alloy samples was investigated by electrochemical impedance spectroscopy and anodic polarization curves in 0.5 mol/L sodium sulfate solution with pH adjusted to 4.0. The results showed that the SAM treatment offered better corrosion protection for the AA3003 alloy than that provided by cerium conversion coating. The combination of cerium conversion and SAM treatments improved the corrosion resistance of the AA3003 alloy due to SAM adsorption on the alloy substrate exposed at the defects in the cerium conversion layer.     

In situ spectroscopy studies of ethanol oxidation reaction using a single fuel cell/ATR-FTIR setup

This work presents a new method to study the ethanol oxidation reaction in a functional fuel cell adapting the single cell on an ATR-FTIR accessory. Using this configuration it was possible to observe the formation of the main products — acetaldehyde and acetic acid — and also measure the decay of the ethanol concentration at various temperatures. Furthermore, it was ascertained that the increment of power density with the temperature increase in the Pt/C anode fuel cell favors the acetaldehyde production. The proposed setup is a very promising characterization technique for studies of in situ electrochemical oxidation of small organic molecules.