Life cycle sustainability analysis (lcsa) of polymer-based piping for plumbing applications

Water conveyance systems play a critical role in modern developed areas. Polymer pipes have been used for about a century, and their convenient physical properties have positioned polymers as the leading material in the piping industry. Having such influence in the market means that changes in current material selection and manufacturing could lead to significant reductions in the footprint associated with their products. Currently, there are no comparative lifecycle assessments that evaluate the different polymer selections commercially available, which makes it hard to determine what products have the least impact on the environment. Understanding how such impacts are relative to each other could lead to conscious customer material selection, and therefore, a reduced negative influence on impact categories such as human health, global warming, ecosystems quality, and natural resources depletion. This study considered nine commercially available materials used for water conveyance: Chlorinated Polyvinyl Chloride (CPVC), Polybutylene (PB), High Density Polyethylene (HDPE), Cross-Linked Polyethylene (PEX), Polyvinylidene Difluoride (PVDF), Acrylonitrile Butadiene Styrene (ABS), Polyvinyl Chloride (PVC), Unplasticized PVC, and Polypropylene (PP). Two different groups were created to understand impact: products used for waste water conveyance (ABS, PVC, UPVC, PP, HDPE, PEX) and those used for drinking water distribution (CPVC, PB, HDPE, PEX, PVDF). To conduct this study, the LCA software tool Simapro 8.0.2 was used to model a cradle-to-gate comparative approach that took into consideration raw material extraction, polymerization, and processing of polymer resins to manufacture pipes. The Ecoinvent 3.01 libraries were used to compile empirical data from the pipe industry in countries all around the world, which was evaluated using the Impact 2002+ and EPD 2008 LCA methods. External Environmental Product Declarations (EPD) played an important role as complementary sources of information for data not available on the Ecoinvent libraries. Material impact was measured using various impact categories, and no material demonstrated lowest impact across all categories. Category prioritization would play a critical role in deciding materials based on what impacts are considered “more important” than others. Since no categories were prioritized in this study, footprint trends were used to provide the most appropriate material recommendation. In the wastewater group, PP demonstrated the lowest impact through most categories, while in the drinking water group, PB exhibited the lowest impact in all but one category. HDPE/PEX made a good second choice within both the drinking and wastewater group categories, while the rest of the materials seemed to have considerably higher impacts. Although data limitations encountered while developing the comparative assessment led to making some assumptions, the results from the study provide a good basis to recommend PB, PP, HDPE, and PEX as the most environmentally conscious material selections, without considering regional or national context

Actin phylogeny of foraminifera and intron evolution

Abstrac

Amphibia, Anura, Strabomantidae, <i>Pristimantis permixtus</i> Lynch, Ruiz-Carranza, and Ardila-Robayo, 1994: Distribution extension, Valle del Cauca, Colombia

Pristimantis permixtus is a moderate sized frog tipically of upper cloud forests and sub-páramo areas. Herewe provide the second record and southernmost of P. permixtus in the Occidental Cordillera in the department of Valle delCauca, Vereda Chicoral, municipality of La Cumbre, Colombia

Time-resolved broadband analysis of slow-light propagation and superluminal transmission of electromagnetic waves in three-dimensional photonic crystals

A time-resolved analysis of the amplitude and phase of THz pulses propagating through three-dimensional photonic crystals is presented. Single-cycle pulses of THz radiation allow measurements over a wide frequency range, spanning more than an octave below, at and above the bandgap of strongly dispersive photonic crystals. Transmission data provide evidence for slow group velocities at the photonic band edges and for superluminal transmission at frequencies in the gap. Our experimental results are in good agreement with finite-difference-time-domain simulations.Comment: 7 pages, 11 figure

Supporting technology for enhanced oil recovery for thermal processes

This report contains the results of efforts under the six tasks of the Ninth Amendment and Extension of Annex IV, Enhanced Oil Recovery Thermal Processes of the Venezuela/USA Agreement. The report is presented in sections (for each of the 6 tasks) and each section contains one or more reports prepared by various individuals or groups describing the results of efforts under each of the tasks. A statement of each task, taken from the agreement, is presented on the first page of each section. The tasks are numbered 62 through 67. The first, second, third, fourth fifth, sixth, seventh, eighth, and ninth reports on Annex IV, [Venezuela MEM/USA-DOE Fossil Energy Report IV-1, IV-2, IV-3, IV-4, IV-5, IV-6, IV-7, and IV-8 (DOE/BETC/SP-83/15, DOE/BC-84/6/SP, DOE/BC-86/2/SP, DOE/BC-87/2/SP, DOE/BC-90/1/SP, DOE/BC-90/1/SP) (DOE/BC-92/1/SP, DOE/BC-93/3/SP, and DOE/BC-95/3/SP)] contain the results from the first 61 tasks. Those reports are dated April 1983, August 1984, March 1986, July 1987, November 1988, October 1991, February 1993, and March 1995 respectively