Facing the potential conflict between economic and environmental challenges, it is essential to investigate the integrated GHG emissions and the emission relationships of all industries in a socio-economic system to support formulation of industrially related legislation. In this study, a disaggregated ecologically-extended input-output (DECEIO) model is developed to investigate integrated GHG emissions and the emission relationships of various industries. A special case study for the Province of Saskatchewan, Canada, is conducted to illustrate the potential benefits of its use in the formulation of industrially related legislation. A disaggregated analysis that contains three GHG types and four emission sources is conducted to gain more insight into the complicated interactions between different industries. It is found that all kinds of emission sources and GHG types should be considered to comprehensively identify the characteristics of emission flows in the socio-economic system. The competitive relationships reflect good interactions in the GHG emission flows and a mutualism relationship reveals effective pathways to mitigate carbon emissions in two sectors simultaneously. In the Province of Saskatchewan, the Agriculture and Forestry sector, Electric Power Generation, Transmission and Distribution sector, Construction sector and Household Consumption sector all rank at the top for GHG emissions and their relationships are mutualistic. Thus, it is vital to propose effective industrial legislation for these industries to realize GHG emission reduction targets.
Sustaining multiple ecosystem service benefits in transboundary river basins is a complex and challenging task in the developing world. This can be attributed to conflicting conservation and human development needs and exacerbated by climate change impacts, especially episodic drought and flooding events. We use a case study from Rwanda in the Kagera River Basin in Eastern Africa to contextualize and examine how land use cover change, water access, and agro-ecosystems are vulnerable to myriad human and natural drivers of change. An integrated framework is employed for a nested social-ecological assessment of ecosystem service benefits drawing upon landscape and vulnerability mapping, agro-commodity value chains, and institutional analyses. The conceptual framework and case study provide leverage points for vertical and horizontal linkages that include cross-sectoral partnerships, multi-level governing networks, integrated water resource management, and livelihood security. Moreover, synergy between development and conservation outcomes can be achieved through joint adaptation planning and stewardship initiatives at the local district level with full participation of resource users and community leaders. These lessons from Rwanda and the Kagera River Basin provide opportunities for mainstreaming adaptation and development planning and building resilience towards regional environmental change in Eastern Africa.
Intraguild predation (IGP), i.e. feeding interaction between two consumers that share the same resource species, is commonly observed in natural food webs. IGP expands vertical niche space and slows down energy flows from lower to higher trophic levels, which potentially affects the diversity and dynamics of food webs. Here, we use food web models to investigate the effects of IGP on species diversity and ecosystem functioning. We first simulate a five‐species food web module with different strengths of IGP at the herbivore and/or carnivore level. Results show that as the strength of IGP within a trophic level increases, the biomass of its resource level increases because of predation release; this increased biomass in turn alters the energy fluxes and biomass of other trophic levels. These results are then extended by subsequent simulations of more diverse food webs. As the strength of IGP increases, simulated food webs maintain (1) higher species diversity at different trophic levels, (2) higher total biomasses at different trophic levels, and (3) larger energy fluxes across trophic levels. Our results challenge the intuitive hypothesis that food web structure should maximize the efficiency of energy transfer across trophic levels; instead, they suggest that the assembly of food webs should be governed by a balance between efficiency (of energy transfer) and persistence (i.e. the maintenance of species and biomasses). Our simulations also show that the relationship between biodiversity and ecosystem functioning (e.g. total biomass or primary production) is much stronger in the presence of IGP, reconciling the contrast from recent studies based on food‐chain and food‐web models. Our findings shed new light on the functional role of IGP and contribute to resolving the debate on structure, diversity and functioning in complex food webs. This article is protected by copyright. All rights reserved.
The North China Plain and the Yangtze River Delta are the two of the most heavily polluted regions in China. Observational studies revealed that 'explosive' PM2.5 mass concentration growths frequently occurred in the two regions. This study analyzed all the PM2.5 mass concentration growth processes from clean condition (i.e., <35 mu g m(-3)) to heavy pollution condition (i.e., >150 mu g m(-3)) in Beijing (BJ) and Shanghai (SH), two representative cities of the two regions, using hourly monitored PM2.5 concentrations during 2013-2016. 173 and 76 growth processes were identified in BJ and SH, respectively. PM2.5 rising rates (PMRR) and dynamic growth durations were calculated to illustrate the characteristics of the growth processes. Hourly particulate chemical composition data and meteorological data in BJ and SH were further analyzed. The 4-year averaged PMRR of PM2.5 total mass were similarly of 7.11 +/- 9.82 mu g m(-3) h(-1) in BJ and 6.71 +/- 6.89 mu g m(-3) h(-1) in SH. A decreasing trend was found for the PM2.5 growth processes in two cities from 2013 to 2016, reflecting the effectiveness of emission controls implemented in the past years. The contributions of particulate components to the PM2.5 total mass growth were different in BJ and SH. Average PMRR value of PM1 organic aerosols (OA), SO24-, NO3-, and NH4+ in BJ was 1.90, 0.95, 0.82, and 0.53 mu g m(-3) h(-1), respectively. Average PMRR of PM2.5 OA, SO42-, NO3-, and NH4+ in SH was 1.70, 1.18, 1.99 and 1.14 mu g m(-3) h(-1), respectively. Based on the contributions of different components, the PM2.5 mass concentration growth processes in BJ and SH were proposed to be classified into 'other components-dominant growth processes', 'all components-contributing growth processes', 'one or more explosive secondary components-dominant growth processes', and 'mixed-factor growth processes'. Potential source contribution function analysis and the meteorological condition analysis showed that source origins and prevailing wind for the two cities during different categories of growth processes had substantial difference. The important source areas included Hebei and Shandong for BJ, and Jiangsu and Anhui for SH. The dominant wind directions during growth processes were northeast, south and southwest in BJ, and were west to north in SH. The results suggested the contributing components, the prevailing wind conditions, and the formation processes were substantially different in the two cities, despite the similar PMRR of PM2.5 total mass during the growth processes between BJ and SH. Future research is needed to study the detailed formation mechanisms of the different PM2.5 mass concentration growth processes in the two cities. (C) 2019 Elsevier Ltd. All rights reserved.
As to gyrotron oscillators, operation at high harmonics is an effective solution to decrease the required magnetic field strengths and improve radiation frequencies towards the terahertz (THz) band. Unfortunately, significant challenges related to a harmonic gyrotron include weak interaction strengths and serious mode competition conditions. In this paper, we report on the excitation strategy and stable-state property of a THz second-harmonic (SH) gyro-BWO with the TE24,3 mode. Such an extremely high-order mode interaction system is inherently capable of providing high power capacity and advanced mode selectivity. A competition-free parameter space is created by increasing the Doppler sensitivity of one fundamental-harmonic (FH) competing mode at low magnetic fields and simultaneously suppressing the Q factor of another FH competing mode in the near-cutoff region at high magnetic fields. The SH quasi-whispering-gallery mode can be stimulated with a medium output power at around 0.5 THz during the FH mode switching process. This work contributes to further exploiting high frequency steps in the high-order multi-mode frequency-tuning gyro-BWO.
A novel gate and passivation dielectric stack consisting of a thin metal-organic chemical vapor deposition (MOCVD) grown in-situ Si3N4 (3 nm) and a thick low-pressure chemical vapor deposition (LPCVD) grown Si3N4 (30 nm) in AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistor (MIS-HEMT) is proposed. The quality of the Si3N4/(Al) GaN interface and the effect on threshold voltage (V-TH) instability and dynamic R-ON in the MIS-HEMTs with/without the in-situ Si3N4 layer are investigated by high-frequency capacitance-voltage (HFCV), quasi-static (QS) C-V (QSCV), time-offly (TOF) stress/measure, and QS I-D-V-DS methods. It is founded that the in-situ Si3N4 interfacial layer is effective in improving the dielectric/III-N interface morphology. As a result, better V-TH stability and lower R-ON, D/R-ON,R-S ratio are observed in devices with the in-situ Si3N4 interfacial layer due to the reduced density of traps close to the dielectric/III-N interface. Time-dependent dielectric breakdown and Weibull performance further verified that the proposed bilayer gate dielectric stack is a promising structure for the high-reliability power transistors.
Seawater reverse osmosis (SWRO) is a commonly used desalination technique owing to its lesser environmental and economic impacts as compared to thermal desalination techniques. Antiscalants are used in SWRO to reduce membrane scaling caused by the supersaturation of salts present in feed water. However, to remain effective in reducing membrane scaling, antiscalants should be highly stable and resistant to biological degradation by seawater microorganisms. In this research, several bacteria from Qatar's seawater were isolated and screened for their ability to use antiscalants as a carbon and energy source. The biodiversity of antiscalant degrading seawater bacteria was demonstrated through combining the techniques of MALDI-TOF MS and principle component analysis. It was found that the bacteria isolated from Qatar's seawater such as H. aquamarina, H. elongata, P. fragi, P. stutzeri and others can degrade antiscalants and use them as a carbon and energy source. It was observed that the growth rates varied based on the type of antiscalant and the bacteria used. Among the tested strains, H. aquamarina, which is also known for its potential to cause biofouling, demonstrated the highest growth rates in antiscalants media. Thus, it was concluded that there is wide variety of bacteria in Qatar's seawater that can biodegrade the antiscalants; reducing their efficiency to combat membrane scaling. Since, these antiscalants will be used as a source of carbon and energy, microbial growth will increase resulting in enhanced membrane biofouling in SWRO.
Adsorption kinetics and conformational changes of a model protein, bovine serum albumin (BSA, 0.1, 0.5, or 1.0 g/L), on the surface of hematite (α-Fe2O3) particles in 39 ± 9, 68 ± 9, and 103 ± 8 nm, respectively, were measured using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. As the particle size increases, the amount of adsorbed BSA decreases, but the loss in the helical structure of adsorbed BSA increases due to the stronger interaction forces between adsorbed BSA and the larger particles. On 39 or 68 nm hematite particles, refolding of adsorbed BSA can be induced by protein–protein interactions, when the protein surface coverage exceeds certain critical values. Two-dimensional correlation spectroscopy (2D-COS) analysis of time-dependent ATR-FTIR spectra indicate that the increase in the amount of adsorbed BSA occurs prior to the loss in the BSA helical structure in the initial stage of adsorption processes, whereas an opposite sequence of the changes to BSA conformation and surface coverage is observed during the subsequent refolding processes. Desorption experiments show that replacing the protein solution with water can quench the refolding, but not the unfolding, of adsorbed BSA. A kinetic model was proposed to quantitatively describe the interplay of adsorption kinetics and conformational change, as well as the effects of particle size and initial protein concentration on the rate constants of elementary steps in protein adsorption onto a mineral surface.
Stretchable and movable 3D structure is a great choice for sensing stretching and bending. This paper reports a novel cross-shaped 3D buckling strain sensor based on polydimethylsiloxane (PDMS) substrate for detecting stretching and bending. Using pre-stretched PDMS, cross-shaped Polyimide (PI) film with conductive silver paint on its top surface as a 2D precursor can pop up as a dynamic 3D structure and possesses capacitive effect and triboelectric effect under different stretching and bending, which can detect stretching directions, strain value, bending axis direction and radius of curvature simultaneously, showing great potential in human and robot applications.
The oil sands industry in Alberta, Canada, represents a large anthropogenic source of secondary organic aerosol (SOA). Atmospheric emissions from oil sands operations are a complex mixture of gaseous and particulate pollutants. Their interaction can affect the formation and characteristics of SOA during plume dispersion, but their chemical evolution remains poorly understood. Oxidative processing of organic vapours in the presence of NOx can lead to particulate organo-nitrate (pON) formation, with important impacts on the SOA budgets, the nitrogen cycle and human health. We provide the first direct field evidence, from ground- and aircraft-based real-time aerosol mass spectrometry, that anthropogenic pON contributed up to half of SOA mass that was freshly produced within the emission plumes of oil sands facilities. Using a top-down emission-rate retrieval algorithm constrained by aircraft measurements, we estimate the production rate of pON in the oil sands region to be similar to 15.5 t d(-1). We demonstrate that pON formation occurs via photo-oxidation of intermediate-volatility organic compounds (IVOCs) in high-NOx environments, providing observational constraints to improve current SOA modelling frameworks. Our ambient observations are supported by laboratory photo-oxidation experiments of IVOCs from bitumen vapours under high-NOx conditions, which demonstrate that pON can account for 30 %-55 % of the observed SOA mass depending on the degree of photochemical ageing. The large contribution of pON to freshly formed anthropogenic SOA illustrates the central role of pON in SOA production from the oil and gas industry, with relevance for other urban and industrial regions with significant anthropogenic IVOC and NOx emissions.
