Composites produced from waste plastic with agricultural and energy sector by-products

A three-stage route to chemically upcycle post-consumer poly(ethylene terephthalate) (PET) to produce high compressive strength composites is reported. This procedure involves initial glycolysis with diethylene glycol to produce a mixture (GPET) comprising oligomers of 2–7 terephthalate units followed by trans/esterification of GPET with fatty acid chains supplied by brown grease, an agricultural by-product of animal fat of relatively low nutritional or fuel value. This process yields PGB comprising a mixture of mono-terephthalate ester derivatives. The olefin units provided by unsaturated fatty acid chains in brown grease were crosslinked by an inverse vulcanization reaction with elemental sulfur to give composites GBS_x (x = wt% S, varied from 80%–90%). The compressive strengths of GBS₈₀ (27.5 ± 2.6 MPa) and GBS₉₀ (19.2 ± 0.8 MPa) exceed the compressive strength required of ordinary Portland cement (17 MPa) for its use in residential building foundations. The current route represents a way to repurpose waste plastic, energy sector by-product sulfur, and agricultural by-product brown grease to give high strength composites with mechanical properties suggesting their possible use to replace less sustainably sourced legacy structural materials.     

Inactivation of tomato pectic enzymes by manothermosonication

 The resistance of tomato pectic enzymes to manothermosonication (MTS), a combined treatment of heat and ultrasound under moderate pressure, was studied. Pectinmethylesterase (PMF) and polygalacturonases (PG) I and II were inactivated much more efficiently by MTS than by simple heating. In MTS inactivation of these enzymes, the effect of heat and ultrasonic waves was synergistic. D values [the time required for the (original) enzyme activity to decrease by 90%] for PME heat inactivation at 62.5  °C were reduced 52.9-fold by MTS and those for PG I at 86  °C and PG II at 52.5  °C, 85.8-fold and 26.3-fold, respectively. Received: 23 January 1998 / Revised version: 23 March 1998     

Intrinsic instability of flame–acoustic coupling

This paper shows that a flame can be an intrinsically unstable acoustic element. The finding is clarified in the framework of an acoustic network model, where the flame is described by an acoustic scattering matrix. The instability of the flame acoustic coupling is shown to become dominating in the limit of no acoustic reflections. This is in contrast to classical standing-wave thermoacoustic modes, which originate from the positive feedback loop between system acoustics and the flame. These findings imply that the effectiveness of passive thermoacoustic damping devices is limited by the intrinsic stability properties of the flame.     

Combining Invariant Features and the ALV Homing Method for Autonomous Robot Navigation Based on Panoramas

Biologically inspired homing methods, such as the Average Landmark Vector, are an interesting solution for local navigation due to its simplicity. However, usually they require a modification of the environment by placing artificial landmarks in order to work reliably. In this paper we combine the Average Landmark Vector with invariant feature points automatically detected in panoramic images to overcome this limitation. The proposed approach has been evaluated first in simulation and, as promising results are found, also in two data sets of panoramas from real world environments.     

Nonlinear analysis of time series generated by schizophrenicpatients

Focusing on a particular feature, the ability to create random rhythms, our study is aimed at the analysis of cognitive performance in patients with schizophrenia, comparing them with normal subjects. We have developed a new cognitive test using methods from nonlinear dynamical systems theory, with the objective of measuring the subject's capacity of developing a random rhythm     

Assessment of fire reaction and fire resistance of Guadua angustifolia kunth bamboo

The main challenge for construction industry today is sustainability. Bamboo has properties that make it sustainable, but its fire behavior remains unknown. This paper presents an exploratory research on fire behavior of Guadua angustifolia kunth (a.k.) bamboo. Fire reaction was assessed through critical heat flux for ignition and flame spread while fire resistance through charring rate and strength variation with temperature. Fire reaction fall within standard limits used for structural woods, while fire resistance results are higher than that of plywood. Based on these preliminary results, Guadua a.k. would be adequate as structural and indoor finishing building material.     

Structure and mechanical properties of a talc‐filled polypropylene/ethylene‐propylene‐diene composite after reprocessing in the melt state

A commercial talc‐filled polypropylene/ethylene‐propylene‐diene terpolymer composite was repeatedly injection molded up to five cycles to study the effects of reprocessing on the structure, morphology, and mechanical properties. Reprocessing did not change either the chemical structure or the thermal behavior of the composite, but led to a slight molecular weight reduction, due to shear–stress‐induced chain scission. Talc and ethylene‐propylene‐diene terpolymer content remained unchanged with reprocessing, whereas size distribution slightly decreased. Young's modulus, yield stress, and Charpy impact strength of the composite did not significantly change even after five cycles, but deformation at break continuously decreased, and it was attributed to the slight molecular weight, talc, and rubber particle size reduction. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Assessing a public health approach to delay onset and progression of adolescent substance use: Latent transition and log-linear analyses of longitudinal family preventive intervention outcomes.

This study examined the effects of the Iowa Strengthening Families Program (ISFP) and the Preparing for the Drug-Free Years program (PDFY) on young adolescent transitions from nonuse of substances to initiation and progression of substance use. Analyses incorporated 3 waves of data collected over a 2.5-year period from 329 rural young adolescents. Outcomes were analyzed by using log-linear models that incorporated substance use status frequencies derived from latent transition analyses. Effects on delayed substance use initiation were shown for both the ISFP and the PDFY at a 2-year follow-up. Also at this follow-up, the PDFY showed effects on delayed progression of use among those previously reporting initiation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)