Improving the Compostability of Natural Fiber-Reinforced Thermoset Composites with a Tertiary Oil Phase

Although fiberglass-reinforced composites play important roles in many industrial applications, the non-biodegradability of the fibers poses some environmental concerns. In this study, bamboo, cotton and hemp are used as natural reinforcing fibers for polyester and epoxy composites. A tertiary oil phase is also added to the matrix and its effect on material biodegradability is characterized. Results show that material biodegradability is increased up to 100% under controlled composting conditions with oil addition. Polyester biodegrades more effectively than epoxy under both macroscopic and microscopic mechanisms. Mechanical strengths of the polyester composites are also found to correlate strongly with material biodegradability.     

Characterization of Compostability and Mechanical Properties for Linseed Oil Resin Composites Reinforced with Natural Fibers

This work characterizes biodegradation behavior and mechanical properties of fiber-reinforced composites made from renewable sources. A linseed oil-based thermoset is used as the polymer matrix. Bamboo, cotton, hemp and fiberglass are used as the reinforcing fibers. Although tensile properties of comparable material systems have been reported in literature, characterization of their compostability has not been studied. Our experimental results show that the natural fibers degrade well under controlled composting conditions, whereas the thermoset polymer matrix did not. Tensile properties of the material are improved significantly with fiberglass reinforcement, whereas the natural fiber reinforcement is able to enhance the material's ductility.     

Network behavior of thermosetting polyimide/multiwalled carbon nanotube composites

In previous published research, network formation has been used to understand morphology and properties in polymer nanocomposites containing carbon nanotubes (CNTs) through measurements of rheological and electrical percolation thresholds, largely in thermoplastic matrices. In this research, these tools are explored as a means to understand network transport mechanisms and changes in CNT dispersion during curing in a thermosetting matrix. Specifically, rheological and electrical measurements were performed on the uncured nanocomposites, and electrical measurements were performed on the cured nanocomposites. The resulting data were applied to a percolation model. The results showed that the uncured resin played a limited role in mediating rheological transport and that little CNT aggregation occurred during curing. The results of this initial work suggest that such a combination of techniques is applicable to understanding dispersion changes resulting from curing and provides complementary insight to that provided by electron microscopy imaging of the same phenomenon.     

Isoprene epoxydiols as precursors to secondary organic aerosol formation: acid-catalyzed reactive uptake studies with authentic compounds

Isoprene epoxydiols (IEPOX), formed from the photooxidation of isoprene under low-NO(x) conditions, have recently been proposed as precursors of secondary organic aerosol (SOA) on the basis of mass spectrometric evidence. In the present study, IEPOX isomers were synthesized in high purity (>99%) to investigate their potential to form SOA via reactive uptake in a series of controlled dark chamber studies followed by reaction product analyses. IEPOX-derived SOA was substantially observed only in the presence of acidic aerosols, with conservative lower-bound yields of 4.7-6.4% for β-IEPOX and 3.4-5.5% for δ-IEPOX, providing direct evidence for IEPOX isomers as precursors to isoprene SOA. These chamber studies demonstrate that IEPOX uptake explains the formation of known isoprene SOA tracers found in ambient aerosols, including 2-methyltetrols, C(5)-alkene triols, dimers, and IEPOX-derived organosulfates. Additionally, we show reactive uptake on the acidified sulfate aerosols supports a previously unreported acid-catalyzed intramolecular rearrangement of IEPOX to cis- and trans-3-methyltetrahydrofuran-3,4-diols (3-MeTHF-3,4-diols) in the particle phase. Analysis of these novel tracer compounds by aerosol mass spectrometry (AMS) suggests that they contribute to a unique factor resolved from positive matrix factorization (PMF) of AMS organic aerosol spectra collected from low-NO(x), isoprene-dominated regions influenced by the presence of acidic aerosols.     

Purification and Use of Glycomacropeptide for Nutritional Management of Phenylketonuria

ABSTRACT:  Individuals with phenylketonuria (PKU) cannot metabolize phenylalanine (Phe) and must adhere to a low-Phe diet in which most dietary protein is provided by a Phe-free amino acid formula. Glycomacropeptide (GMP) is the only naturally occurring protein that does not contain Phe, and is of interest as a source of protein for dietary management of PKU. However, commercially available GMP contains too much Phe from residual whey proteins and does not contain adequate levels of all the indispensable amino acids to provide a nutritionally complete protein. The aim of this study was to increase purity of GMP and develop a mass balance calculation for indispensable amino acid supplementation of GMP foods. Cation exchange chromatography, ultrafiltration/diafiltration, and lyophilization were used at the pilot plant scale to decrease Phe. Enough purified GMP (5 kg) was manufactured to provide 15 PKU subjects with a 4-d diet in which the majority of protein was from GMP foods. A mass balance was used to supplement GMP foods so that all indispensable amino acids met or exceeded the daily recommended intake. GMP foods were tested in a human clinical trial as a replacement for the traditional amino acid formula. Nutritionally complete GMP foods created with high purity GMP provide individuals with PKU with more options to manage PKU, which may lead to improved compliance and quality of life.     

The influence of product knowledge on the relative importance of extrinsic product attributes of wine

The purpose of this paper is to examine the influence of product knowledge, both subjective and objective, on the relative importance of four extrinsic product attributes of wine, namely price, age, brand and region of origin. The relative importance of four product attributes is evaluated comparative to consumers’ self-reported and objectively measured knowledge of wine, using the conjoint analysis technique. The results suggest that product knowledge does influence the relative importance of extrinsic wine attributes in product evaluation, with the price of wine shown to be the dominant attribute regardless of the level of product knowledge expertise. Brand, age and region of origin received differing rankings of importance. Across all four levels of product knowledge, consumers navigate their evaluative product decisions according to the midpoint between most and least expensive wines in their consideration set. Price sensitivity appears to heavily impact consumer evaluation strategies, which serves to inform wine pricing strategies.     

Sugar Recognition: Designing Artificial Receptors for Applications in Biological Diagnostics and Imaging

At the cellular level, numerous processes ranging from protein folding to disease development are mediated by a sugar‐based molecular information system that is much less well known than its DNA‐ or protein‐based counterparts. The subtle structural diversity of such sugar tags nevertheless offers an excellent, if challenging, opportunity to design receptors for the selective recognition of biorelevant sugars. Over the past 40 years, growing interest in the field of sugar recognition has led to the development of several promising artificial receptors, which could soon find widespread use in medical diagnostics and cell imaging.     

Towards a swarm of agile micro quadrotors

We describe a prototype 75 g micro quadrotor with onboard attitude estimation and control that operates autonomously with an external localization system. The motivation for designing quadrotors at this scale comes from two observations. First, the agility of the robot increases with a reduction in size, a fact that is supported by experimental results in this paper. Second, smaller robots are able to operate in tight formations in constrained, indoor environments. We describe the hardware and software used to operate the vehicle as well our dynamic model. We also discuss the aerodynamics of vertical flight and the contribution of ground effect to the vehicle performance. Finally, we discuss architecture and algorithms to coordinate a team of these quadrotors, and provide experimental results for a team of 20 micro quadrotors.     

Powder characterisation techniques and effects of powder characteristics on part properties in powder-bed fusion processes

Powder-bed fusion is a class of Additive Manufacturing (AM) processes that bond successive layers of powder to facilitate the creation of parts with complex geometries. As AM technology transitions from the fabrication of prototypes to end-use parts, the understanding of the powder properties needed to reliably produce parts of acceptable quality becomes critical. Consequently, this has led to the use of powder characterisation techniques such as scanning electron microscopy, laser light diffraction, X-ray photoelectron spectroscopy, and differential thermal analysis to study the effect of powder characteristics on part properties. Utilisation of these powder characterisation methods to study particle morphology, chemistry, and microstructure has resulted in significant strides being made towards the optimisation of powder properties. This paper reviews methods commonly used in characterising AM powders, and the effects of powder characteristics on the part properties in powder-bed fusion processes.