Warm-Mix Asphalt Study: Evaluation of Rubberized Hot- and Warm-Mix Asphalt with Respect to Emissions

In recent years, warm mix asphalt (WMA) technologies have been used to modify asphalt binders, with the aims of decreasing production and construction temperatures, reducing fumes and emissions, retaining the properties of the mix during long haul distances, and improving workability. Reduced production temperatures at the plant and during paving and compaction are believed to reduce emissions from the asphalt. The objective of this research study was to quantify the potential environmental benefits during paving operations with respect to the reduction of volatile and semi-volatile organic compounds and polycyclic aromatic hydrocarbons to confirm or refute this hypothesis. Asphalt plant stack emissions were not assessed as part of this study. A portable “flux” chamber was designed and fabricated to capture and directly measure emissions during paving operations. An analytical method was developed to identify and quantify alkane emissions using gas chromatography mass spectrometry (GC-MS). A separate method was developed for identification and characterization of trace level polycyclic aromatic hydrocarbon compounds in the asphalt fumes. The results demonstrated that the warm-mix asphalt technology type, plant mixing temperature, and level of compaction significantly influence emissions characteristics throughout paving operations. Depending on these variables, most warm-mix technologies appear to have potential for reducing emissions during transport and paving operations. Key findings from the study include: The majority of the reactive organic gases are volatilized in the first hour after sampling initiation. There is a significant difference between emissions concentrations from loose mix and those recorded immediately after compaction. Gaseous phase PAH compounds in asphalt fumes are mainly low molecular weight compounds and are present at trace levels. The concentrations vary depending on the temperature of the mix at the time of sampling. Particulate phase PAHs were below the detection limit of this study for all the mixes. The results confirmed that typical asphalt production temperatures are not high enough to initiate significant PAH formation. The total alkane emissions from the warm-mixes were, in most instances, significantly lower than those measured from the hot-mixes (e.g., 117 µg/m3 from one of the warm-mixes compared to 2,516 µg/m3 from the hot-mix control). In some instances, specific warm-mixes had higher alkane concentrations than the hot-mix controls. Consequently, any generalization with regard to emissions reduction through the use of warm-mix asphalt is inappropriate. PAH concentrations correlated with initial mix production temperature, with those warm-mixes produced at the lowest temperatures showing the lowest PAH concentrations

A New Length-Based Algebraic Multigrid Clustering Algorithm

Clustering algorithms have been used to improve the speed and quality of placement. Traditionally,clustering focuses on the local connections between cells. In this paper, a new clustering algorithmthat is based on the estimated lengths of circuit interconnects and the connectivity is proposed. Inthe proposed algorithm, first an a priori length estimation technique is used to estimate the lengthsof nets. Then, the estimated lengths are used in a clustering framework to modify a clusteringtechnique based on algebraic multigrid (AMG), that finds the cells with the highest connectivity.Finally, based on the results from the AMG-based process, clusters are made. In addition, anew physical unclustering technique is proposed. The results show a significant improvement,reductions of up to 40%, in wire length can be achieved when using the proposed technique withthree academic placers on industry-based circuits. Moreover, the runtime is not significantlydegraded and can even be improved.Peer Reviewe

Synthetic hepcidin causes rapid dose-dependent hypoferremia and is concentrated in ferroportin-containing organs

Hepcidin is the principal iron regulatory hormone and its overproduction contributes to anemia of inflammation (AI). In vitro, hepcidin binds to and induces the degradation of the exclusive iron exporter ferroportin. We explored the effects and distribution of synthetic hepcidin in the mouse. A single intraperitoneal injection of hepcidin caused a rapid fall of serum iron in a dose-dependent manner, with a 50-mu g dose resulting in iron levels 80% lower than in control mice. The full effect was seen within only 1 hour, consistent with a blockade of iron export from tissue stores and from macrophages involved in iron recycling. Serum iron remained suppressed for more than 48 hours after injection. Using radiolabeled hepcidin, we demonstrated that the serum concentration of hepcidin at the 50 mu g dose was 1.4 mu M, consistent with the inhibitory concentration Of 50% (IC50) Of hepcidin measured in vitro. Radiolabeled hepcidin accumulated in the ferroportin-rich organs, liver, spleen, and proximal duodenum. Our study highlights the central role of the hepcidin-ferroportin interaction in iron homeostasis. The rapid and sustained action of a single dose of hepcidin makes it an appealing agent for the prevention of iron accumulation in hereditary hemochromatosis

A comparison of microvascular responses to visible and near-infrared lasers.

Background and objectivePulsed dye laser (PDL) is a commonly used treatment for Port Wine Stain birthmarks (PWS). However, deeper components of PWS are often resistant to PDL. Deeper penetrating lasers, including the long pulsed Neodymium:Yttrium Aluminum Garnet (Nd:YAG) laser have been used, but carry greater risk. This study evaluates the distinct blood vessel thermal responses to visible (595 nm) and near infrared (1,064 nm) lasers using animal and numerical models.Study design/materials and methodsBlood vessels in the rodent dorsal skin chamber (DSC) were irradiated by a 595 nm PDL and a long-pulsed 1,064 nm Nd:YAG laser. Laser-induced immediate and 1-hour post-structural and functional changes in the vessels were documented. Numerical simulations were conducted using a 1,000 µm depth SD mouse skin fold to simulate experimental conditions.ResultsPDL irradiation produced immediate blood vessel hemorrhage. Modeling indicated this occurs due to preferential heating of the superior parts of large blood vessels. Nd:YAG irradiation resulted in blood vessel constriction; modeling indicated more uniform heating of vessel walls.ConclusionPDL and Nd:YAG lasers result in distinct tissue responses. This supports different observable clinical treatment end points when using these devices. Vessel constriction associated with the Nd:YAG may be more difficult to observe and is one reason this device may carry greater risk

Investigation of Wet-Process Asphalt Rubber Binder Testing with Modified Dynamic Shear Rheometer: Interim Report on Screening Tests

In the United States, the Superpave Asphalt Binder Performance Grading (PG) system proposed by the Strategic Highway Research Program (SHRP) is the most common method used to characterize the performance-related properties of conventional and polymer-modified asphalt binders. Dynamic modulus (G*) and phase angle (δ) are the two main binder properties and they are measured using a dynamic shear rheometer (DSR) with parallel plate geometry and either a 1 mm or 2 mm gap between the plates. Since these Superpave parameters were developed for binders that do not contain additives or particulates, the California Department of Transportation (Caltrans) does not use them as asphalt rubber binder specification criteria. Instead, penetration and viscosity are used as acceptance of quality control; however, these parameters do not necessarily provide a satisfactory link between the measured binder properties and potential performance in the field over a range of operating temperatures. In California, current specifications require that crumb rubber particles used to produce asphalt rubber binder in the “wet process” must be smaller than 2.36 mm (i.e., 100 percent passing the #8 sieve), and typically these particles vary in size between 1 mm and 2 mm. As a consequence, when the parallel plate geometry is used to test this type of binder, the larger rubber particles can contact the plates; if this occurs, the rubber particle rheology can potentially dominate the results, which in turn may not be representative of the modified binder as a whole. To address this problem, a potentially more appropriate DSR testing protocol using concentric cylinder geometry was investigated in this study to explore an alternative means of determining the performance properties of asphalt rubber binders. In the first phase of the study, documented in this technical memorandum, a series of tests were undertaken to compare the two geometries and to assess which binder properties influence the results from the testing approaches. The interim results indicate that there is no significant difference between the concentric cylinder and parallel plate geometries in terms of the G*/sinδ after testing on a range of different binders and asphalt rubber binders with finer crumb rubber particle sizes (i.e.  <250 μm). However, the correlations between results from the geometries were increasingly weaker with increasing crumb rubber particle size, indicating some potential influence of larger sizes on the results of the testing using parallel plates. The concentric cylinder geometry resulted in relatively lower values of G*/sinδ compared to samples tested with the parallel plate geometry. This difference is provisionally attributed to large rubber particles touching both plates, and to edge effects issues. The proposed alternative approach to measuring the rheological properties of asphalt rubber binder is considered feasible, and that with its use the edge effect and trimming issues can be eliminated. However, the concentric cylinder method requires a longer testing time and a larger binder sample than the parallel plate test method. The testing will be continued to develop proposed revised quality control procedures for testing asphalt rubber binders used on Caltrans projects.

Maternal bisphenol A exposure alters rat offspring hepatic and skeletal muscle insulin signaling protein abundance

BackgroundThe obesogenic and diabetogenic effects of the environmental toxin bisphenol A during critical windows of development are well recognized. Liver and skeletal muscle play a central role in the control of glucose production, utilization, and storage.ObjectivesWe hypothesized that maternal bisphenol A exposure disrupts insulin signaling in rat offspring liver and skeletal muscle. We determined the protein expression of hepatic and skeletal muscle insulin signaling molecules including insulin receptor beta, its downstream target insulin receptor substrate 1 and glucose transporters (glucose transporter 2, glucose transporter 4), and hepatic glucose-regulating enzymes phosphoenolpyruvate carboxykinase and glucokinase.Study designRat dams had ad libitum access to filtered drinking water (control) or drinking water with bisphenol A from 2 weeks prior to mating and through pregnancy and lactation. Offspring litters were standardized to 4 males and 4 females and nursed by the same dam. At weaning, bisphenol A exposure was removed from all offspring. Glucose tolerance was tested at 6 weeks and 6 months. Liver and skeletal muscle was collected from 3 week old and 10 month old offspring for protein expression (Western blot) of insulin receptor beta, insulin receptor substrate 1, glucose transporter 2, glucose transporter 4, phosphoenolpyruvate carboxykinase, and glucokinase.ResultsMale, but not female, bisphenol A offspring had impaired glucose tolerance at 6 weeks and 6 months. Both male and female adult offspring had higher glucose-stimulated insulin secretion as well as the ratio of stimulated insulin to glucose. Male bisphenol A offspring had higher liver protein abundance of the 200 kDa insulin receptor beta precursor (2-fold), and insulin receptor substrate 1 (1.5-fold), whereas glucose transporter 2 was 0.5-fold of the control at 3 weeks of age. In adult male bisphenol A offspring, the abundance of insulin receptor beta was higher (2-fold) and glucose transporter 4 was 0.8-fold of the control in skeletal muscle. In adult female bisphenol A offspring, the skeletal muscle protein abundance of glucose transporter 4 was 0.4-fold of the control.ConclusionMaternal bisphenol A had sex- and tissue-specific effects on insulin signaling components, which may contribute to increased risk of glucose intolerance in offspring. Glucose transporters were consistently altered at both ages as well as in both sexes and may contribute to glucose intolerance. These data suggest that maternal bisphenol A exposure should be limited during pregnancy and lactation