De La Salle University

About: De La Salle University is a education organization based out in Manila, Philippines. It is known for research contribution in the topics: Population & Computer science. The organization has 2951 authors who have published 4374 publications receiving 49567 citations. The organization is also known as: Pamantasang De La Salle.

Isomer-specific accumulation and toxic assessment of polychlorinated biphenyls, including coplanar congeners, in cetaceans from the North Pacific and Asian coastal waters

Abstract: To elucidate the global distribution and toxicological impacts of polychlorinated biphenyls (PCBs) on cetaceans, the present study determined the concentrations of individual PCB congeners, including toxic non-ortho (IUPAC Nos. 77, 126, 169) and mono-ortho (IUPAC Nos. 105, 118, 156) coplanar congeners, in the blubber of 10 species of adult male odontocetes collected from several locations in the North Pacific Ocean and along coastal waters of Japan, Hong Kong, the Philippines, and India during 1985–1997. Total PCB concentrations in cetaceans from temperate and cold waters were higher than those in cetaceans from tropical regions. Residue levels were found to be the highest in Fraser's dolphins collected off Kii Peninsula, Japan, and hump-backed dolphins from Hong Kong, reflecting serious marine pollution by PCBs in industrialized Asian countries. Penta- and hexa-chlorobiphenyls were the predominant PCB congeners, accounting for about 70% of the total PCBs. 2,3,7,8-Tetrachlorodibenzo-p-dioxin equivalents (TEQs) of non- and mono-ortho coplanar PCBs in the blubber of cetaceans ranged from 36 (in spinner dolphins from the Philippines) to 510 pg/g wet weight (in hump-backed dolphins from Hong Kong). Toxic evaluation of coplanar PCBs using the TEQ concept indicates an greater impact on cetaceans from mid-latitudes. Toxicity contribution of mono-ortho congener IUPAC 118 was prominent in species from high latitude oceans, such as the Bering Sea and the North Pacific, whereas non-ortho congener IUPAC 126 accounted for the highest contribution in cetaceans from lower latitude regions, such as the Philippines and India. The estimated TEQ concentrations in the blubber of some cetacean species, such as northern right whale dolphin and Pacific white-sided dolphin from the northern North Pacific, Dall's porpoise from the Japan Sea, striped dolphin off Sanriku and Fraser's dolphin off Kii Peninsula, Japan, hump-backed dolphin and finless porpoise from Hong Kong, exceeded the levels associated with immunosuppression in harbour seals.

Green preparation and characterization of tentacle-like silver/copper nanoparticles for catalytic degradation of toxic chlorpyrifos in water

Abstract: The synthesis of bimetallic nanoparticles is gaining attention due to a number of interesting and striking new properties that can be derived from the combination of two metals. In this study, bimetallic silver/copper (Ag/Cu) nanoparticles were prepared by co-reduction method using aqueous leaf extracts of Carica papaya as reducing agent. The synthesized nanoparticles showed a single UV–vis peak with a maximum absorption at 776 nm. The SEM and TEM images of bimetallic Ag/Cu nanoparticles displayed, among others, a unique star-like structure. HR-TEM mapping revealed uniform distribution of Ag & Cu forming a bimetallic nanoparticle. The bimetallic Ag/Cu has an average hydrodynamic particle size of 420.7 nm (DLS) and TEM size of ∼150 nm. The presence of elemental Ag, Cu, C, N and O was confirmed in EDX spectra suggesting nitrogen containing metabolites capping the bimetallic Ag/Cu nanoparticles. The XRD patterns of bimetallic Ag/Cu nanoparticles displayed crystallinity with observed diffraction peaks corresponding to Ag, Ag2O and CuO. The synthesized bimetallic nanoparticles were then utilized for water purification application using the toxic pollutant, chlorpyrifos pesticide, as a model. Results showed that bimetallic Ag/Cu nanoparticles are efficient agents to promote degradation of chlorpyrifos in water, indicating the high potential of green synthesized nanometals for purifying water from pesticide contamination.

Crisp and fuzzy integer programming models for optimal carbon sequestration retrofit in the power sector

Abstract: Carbon capture and storage (CCS) is one of the interim technologies to mitigate greenhouse gas emissions from stationary sources such as power plant and large industrial facilities. CCS allows for continued utilization of fossil fuels (e.g. coal, natural gas and oil), which are still relatively inexpensive and reliable in comparison to inherently low-carbon renewable resources (e.g. wind, solar etc.). On the other hand, retrofitting power plants for carbon capture (CC) entails major capital costs as well as reduction of thermal efficiency and power output. This paper presents integer programming optimization models for planning the retrofit of power plants at the regional, sectoral or national level. In addition to the base case (i.e., non-fuzzy or crisp) formulation, two fuzzy extensions are given to account for the inherent conflict between environmental and economic goals, as well as parametric uncertainties pertaining to the emerging CC technologies. Case studies are shown to illustrate the modeling approach.

Understanding taxi travel patterns

Abstract: Taxis play important roles in modern urban transportation systems, especially in mega cities. While providing necessary amenities, taxis also significantly contribute to traffic congestion, urban energy consumption, and air pollution. Understanding the travel patterns of taxis is thus important for addressing many urban sustainability challenges. Previous research has primarily focused on examining the statistical properties of passenger trips, which include only taxi trips occupied with passengers. However, unoccupied trips are also important for urban sustainability issues because they represent potential opportunities to improve the efficiency of the transportation system. Therefore, we need to understand the travel patterns of taxis as an integrated system, instead of focusing only on the occupied trips. In this study we examine GPS trajectory data of 11,880 taxis in Beijing, China for a period of three weeks. Our results show that taxi travel patterns share similar traits with travel patterns of individuals but also exhibit differences. Trip displacement distribution of taxi travels is statistically greater than the exponential distribution and smaller than the truncated power-law distribution. The distribution of short trips (less than 30 miles) can be best fitted with power-law while long trips follow exponential decay. We use radius of gyration to characterize individual taxi’s travel distance and find that it does not follow a truncated power-law as observed in previous studies. Spatial and temporal regularities exist in taxi travels. However, with increasing spatial coverage, taxi trips can exhibit dual high probability density centers.

Planning of carbon capture and storage with pinch analysis techniques

Abstract: Carbon capture and storage (CCS) is a means for reducing carbon dioxide (CO2) emissions from fossil fuel combustion in power generation and industrial processes. It involves the capture of CO2 for subsequent storage in various geological formations. The selection and matching of the power plants and storage sites are often an issue of optimisation due to various constraints, i.e., time of availability, injection rate, and storage capacity limits. In this work, a novel graphical targeting tool based on pinch analysis is proposed to address the planning problem of the storage of captured CO2 from power generating plants into corresponding reservoirs. The main consideration for the problem is the time of availability of the latter, since reservoirs need to be developed prior to CO2 storage. The time limitation is addressed by the graphical technique where time is taken as the governing element in solving the problem. Hypothetical examples are used to elucidate the proposed approach.