Testing for Cointegration with Temporally Aggregated and Mixed‐Frequency Time Series

We examine the effects of mixed sampling frequencies and temporal aggregation on the size of commonly used tests for cointegration, and we find that these effects may be severe. Matching sampling schemes of all series generally reduces size distortion, and the nominal size is obtained asymptotically only when all series are skip sampled in the same way – for example, end‐of‐period sampling. We propose and analyse mixed‐frequency versions of the cointegration tests in order to control the size when some high‐frequency data are available. Otherwise, when no high‐frequency data are available, we discuss controlling size using bootstrapped critical values. We test stock prices and dividends for cointegration as an empirical demonstration.     

Surface properties of self-assembled monolayer films of tetra-substituted cobalt, iron and manganese alkylthio phthalocyanine complexes

Self-assembled monolayer (SAM) films of iron (SAM-1), cobalt (SAM-2) and manganese (SAM-3) phthalocyanine complexes, tetra-substituted with diethylaminoethanethio at the non-peripheral positions, were formed on gold electrode in dimethylformamide (DMF). Electrochemical, impedimentary and surface properties of the SAM films were investigated. Cyclic voltammetry was used to investigate the electrochemical properties of the films. Ability of the films to inhibit common faradaic processes on bare gold surface (gold oxidation, solution redox chemistry of [Fe(H₂O)₆]³⁺/[Fe(H₂O)₆]²⁺ and underpotential deposition (UDP) of copper) was investigated. Electrochemical impedance spectroscopy (EIS), using [Fe(CN)₆]^3−/4− redox process as a probe, offered insights into the electrical properties of the films/electrode interfaces. Surface properties of the films were probed using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The films were employed for the electrocatalytic oxidation of the pesticide, carbofuran. Electrocatalysis was evidenced from enhanced current signal and less positive oxidation potential of the pesticide on each film, relative to that observed on the bare gold electrode. Mechanism of electrocatalytic oxidation of the pesticide was studied using rotating disc electrode voltammetry.     

The influence of oxidation reduction potential and water treatment processes on quartz lamp sleeve fouling in ultraviolet disinfection reactors

Ultraviolet (UV) disinfection systems are incorporated into drinking water production facilities because of their broad-spectrum antimicrobial capabilities, and the minimal disinfection by-product formation that generally accompanies their use. Selection of an optimal location for a UV system within a drinking water treatment facility depends on many factors; a potentially important consideration is the effect of system location on operation and maintenance issues, including the potential for fouling of quartz surfaces. To examine the effect of system location on fouling, experiments were conducted at a groundwater treatment facility, wherein aeration, chlorination, and sand filtration were applied sequentially for treatment. In this facility, access to the water stream was available prior to and following each of the treatment steps. Therefore, it was possible to examine the effects of each of these unit operations on fouling dynamics within a UV system. Results indicated zero-order formation kinetics for the fouling reactions at all locations. Increases in oxidation reduction potential, caused by water treatment steps such as aeration and chlorination, increased the rate of sleeve fouling and the rate of irradiance loss within the reactor. Analysis of metals in the sleeve foulant showed that calcium and iron predominate, and relative comparisons of foulant composition to water chemistry highlighted a high affinity for incorporation into the foulant matrix for both iron and manganese, particularly after oxidizing treatment steps. Fouling behavior was observed to be in qualitative agreement with representations of the degree of saturation, relative to the metal:ligand combinations that are believed to comprise a large fraction of the foulants that accumulate on the surfaces of quartz jackets in UV systems used to treat water.     

Effects of processing conditions and packaging material on the quality attributes of dry‐roasted peanuts

Five different processing conditions of raw shelled unblanched peanuts were investigated. The first two treatments involved soaking the peanuts in tap water for 10 and 30 min respectively, then mixing thoroughly with dry NaCl before roasting. Another two treatments involved soaking the peanuts in saturated brine solution for 10 and 30 min respectively before roasting. Unsalted roasted peanuts served as the control. Packaging and storage studies were carried out by packaging the differently treated dry‐roasted peanuts in four different packaging materials and storing them under three different relative humidities for 3 months at ambient temperature. Proximate composition, NaCl content, peroxide value and thiobarbituric acid value were determined and sensory evaluation tests were carried out. Salting was found to improve the taste, flavour and overall acceptability of dry‐roasted peanuts but had no effect on shelf‐life. Peanuts treated in saturated brine solution for 30 min before roasting were the most preferred. The control packaging material, 18 µm transparent polyethylene, was found to be inadequate for protecting the quality attributes of dry‐roasted peanuts, with mould growth being observed on the 42nd day of storage at 80% relative humidity. However, acceptable results were obtained with 45 µm transparent polypropylene. The mean sensory scores and objective tests were found to be negatively correlated. © 2002 Society of Chemical Industry     

Fatigue properties of hemp and glass fiber composites

The fatigue properties of nonwoven randomly oriented short hemp fiber mat and chopped strand mat (CSM) glass fiber reinforced polyester composites have been studied, mainly in tension–tension mode. Despite having poorer absolute fatigue strength, the hemp fiber composites exhibited less fatigue sensitivity as compared with the CSM glass fiber composites in tension–tension fatigue. This could be correlated with the lower stiffness degradation observed during fatigue of the hemp fiber composites as compared with the glass fiber composites at the same normalized peak stress levels. Also, images recorded during fatigue loading showed that the hemp fiber composites were better at resisting crack formation and growth than the glass fiber composites. These results suggest that hemp fiber composites have the potential to replace glass fiber composites in applications where components are subjected to fatigue loads but the stress levels are of moderate value. POLYM. COMPOS., 35:1926–1934, 2014. © 2014 Society of Plastics Engineers     

From coffee industry waste materials to skin‐friendly products with improved skin fat levels

Spent coffee grounds (SCG), which are the residue obtained from the treatment of coffee with hot water or steam, can be used for industrial applications, due to the high content in lipids. The cosmetic products might be a suitable application for these types of residues because the barrier properties of the stratum corneum (SC) are largely dependent on the intactness of the lipid lamellae that surrounds the corneocytes. The purpose of this work was to assess the feasibility of using the lipid fraction of SCG extracted with supercritical carbon dioxide in the development of new cosmetic formulations with improved skin lipids (sebum) and hydration. The use of spent coffee lipid extract in cosmetic industry seems to be a suitable approach to recycle the wastes from coffee industry. Emulsion containing 10% of the lipid fraction of SCG (SpentCofOil cream) presented promising characteristics in the improvement of sebum skin levels with a good acceptance by consumers when compared to an emulsion containing 10% w/w of green coffee oil (GreenCofOil cream) and a placebo without coffee oil (NoCofOil cream). Practical applications: In this work, the authors develop and characterize a cream containing 10% of the lipid fraction of SCG extracted with supercritical carbon dioxide with improved skin lipids (sebum) and hydration.     

On the reliability of electrostatic NEMS/MEMS devices: Review of present knowledge on the dielectric charging and stiction failure mechanisms and novel characterization methodologies

This paper reviews the state of the art knowledge related to critical failure mechanisms in electrostatic micro- and nano-electromechanical systems (MEMS and NEMS) which are the dielectric charging and stiction. It describes also the recent employed nanoscale characterization techniques for these phenomena based on Kelvin probe force microscopy (KPFM) and force–distance curve measurements. The influence of relative humidity and dielectric deposition conditions on the charging/discharging processes is discussed. Moreover, different stiction mechanisms induced by electrostatic force and/or meniscus formation are analyzed. Finally, novel characterization methods are presented and used to correlate between the results from MEMS devices and metal–insulator–metal (MIM) capacitors. These methods are employed in view of application in electrostatic capacitive MEMS switches and could be easily extended to explore other NEMS/MEMS devices. The study provides an accurate understanding of the charging and stiction related failure mechanisms, presents guidelines for a proper packaging environment, and reveals precise explanations for the literature reported device level measurements of electrostatic MEMS devices.