On the sources of methane to the los angeles atmosphere

We use historical and new atmospheric trace gas observations to refine the estimated source of methane (CH(4)) emitted into California's South Coast Air Basin (the larger Los Angeles metropolitan region). Referenced to the California Air Resources Board (CARB) CO emissions inventory, total CH(4) emissions are 0.44 ± 0.15 Tg each year. To investigate the possible contribution of fossil fuel emissions, we use ambient air observations of methane (CH(4)), ethane (C(2)H(6)), and carbon monoxide (CO), together with measured C(2)H(6) to CH(4) enhancement ratios in the Los Angeles natural gas supply. The observed atmospheric C(2)H(6) to CH(4) ratio during the ARCTAS (2008) and CalNex (2010) aircraft campaigns is similar to the ratio of these gases in the natural gas supplied to the basin during both these campaigns. Thus, at the upper limit (assuming that the only major source of atmospheric C(2)H(6) is fugitive emissions from the natural gas infrastructure) these data are consistent with the attribution of most (0.39 ± 0.15 Tg yr(-1)) of the excess CH(4) in the basin to uncombusted losses from the natural gas system (approximately 2.5-6% of natural gas delivered to basin customers). However, there are other sources of C(2)H(6) in the region. In particular, emissions of C(2)H(6) (and CH(4)) from natural gas seeps as well as those associated with petroleum production, both of which are poorly known, will reduce the inferred contribution of the natural gas infrastructure to the total CH(4) emissions, potentially significantly. This study highlights both the value and challenges associated with the use of ethane as a tracer for fugitive emissions from the natural gas production and distribution system.     

Roles of sulfuric acid in elemental mercury removal by activated carbon and sulfur-impregnated activated carbon

This work addresses the discrepancy in the literature regarding the effects of sulfuric acid (H(2)SO(4)) on elemental Hg uptake by activated carbon (AC). H(2)SO(4) in AC substantially increased Hg uptake by absorption particularly in the presence of oxygen. Hg uptake increased with acid amount and temperature exceeding 500 mg-Hg/g-AC after 3 days at 200 °C with AC treated with 20% H(2)SO(4). In the absence of other strong oxidizers, oxygen was able to oxidize Hg. Upon oxidation, Hg was more readily soluble in the acid, greatly enhancing its uptake by acid-treated AC. Without O(2), S(VI) in H(2)SO(4) was able to oxidize Hg, thus making it soluble in H(2)SO(4). Consequently, the presence of a bulk H(2)SO(4) phase within AC pores resulted in an orders of magnitude increase in Hg uptake capacity. However, the bulk H(2)SO(4) phase lowered the AC pore volume and could block the access to the active surface sites and potentially hinder Hg uptake kinetics. AC treated with SO(2) at 700 °C exhibited a much faster rate of Hg uptake attributed to sulfur functional groups enhancing adsorption kinetics. SO(2)-treated carbon maintained its fast uptake kinetics even after impregnation by 20% H(2)SO(4).     

Kinetics of Ni sorption in soils: roles of soil organic matter and Ni precipitation

The kinetics of Ni sorption to two Delaware agricultural soils were studied to quantitatively assess the relative importance of Ni adsorption on soil organic matter (SOM) and the formation of Ni layered double hydroxide (Ni-LDH) precipitates using both experimental studies and kinetic modeling. Batch sorption kinetic experiments were conducted with both soils at pH 6.0, 7.0, and 7.5 from 24 h up to 1 month. Time-resolved Ni speciation in soils was determined by X-ray absorption spectroscopy (XAS) during the kinetic experiments. A kinetics model was developed to describe Ni kinetic reactions under various reaction conditions and time scales, which integrated Ni adsorption on SOM with Ni-LDH precipitation in soils. The soil Ni speciation (adsorbed phases and Ni-LDH) calculated using the kinetics model was consistent with that obtained through XAS analysis during the sorption processes. Under our experimental conditions, both modeling and XAS results demonstrated that Ni adsorption on SOM was dominant in the short term and the formation of Ni-LDH precipitates accounted for the long-term Ni sequestration in soils, and, more interestingly, that the adsorbed Ni may slowly transfer to Ni-LDH phases with longer reaction times.     

Copper oxide nanoparticle mediated DNA damage in terrestrial plant models

Engineered nanoparticles, due to their unique electrical, mechanical, and catalytic properties, are presently found in many commercial products and will be intentionally or inadvertently released at increasing concentrations into the natural environment. Metal- and metal oxide-based nanomaterials have been shown to act as mediators of DNA damage in mammalian cells, organisms, and even in bacteria, but the molecular mechanisms through which this occurs are poorly understood. For the first time, we report that copper oxide nanoparticles induce DNA damage in agricultural and grassland plants. Significant accumulation of oxidatively modified, mutagenic DNA lesions (7,8-dihydro-8-oxoguanine; 2,6-diamino-4-hydroxy-5-formamidopyrimidine; 4,6-diamino-5-formamidopyrimidine) and strong plant growth inhibition were observed for radish (Raphanus sativus), perennial ryegrass (Lolium perenne), and annual ryegrass (Lolium rigidum) under controlled laboratory conditions. Lesion accumulation levels mediated by copper ions and macroscale copper particles were measured in tandem to clarify the mechanisms of DNA damage. To our knowledge, this is the first evidence of multiple DNA lesion formation and accumulation in plants. These findings provide impetus for future investigations on nanoparticle-mediated DNA damage and repair mechanisms in plants.     

Properties of extruded expandable breadfruit products

It is vital to process breadfruit in order to develop new value-added products with improved sensory and physicochemical characteristics. In this research, dried breadfruit was extruded with a twin screw extruder and effects of barrel temperature, moisture content, feeding rate and screw speed on product physicochemical properties and process energy consumption were studied. Quadratic models were obtained to predict the product quality under various processing conditions. The best range of crispness of the extrudate was from 2.0 to 3.5N/s, hardness from 60 to 75 N and bulk density from 0.3 to 0.38 g/cm³. Corresponding operating conditions of feeding rate, temperature, screw speed and moisture content to obtain best results of crispness, hardness and bulk density were 16 kg/h, 130 °C, 160 rpm, 22 g/100 g; 22 kg/h, 150 °C, 160rpm, 22 g/kg; 19 kg/h, 140 °C, 115 rpm, 19 g/100 g; and 25 kg/h, 140 °C, 145 rpm, 19 g/100 g, respectively. The linear term of screw speed significantly effected all indexes (p < 0.001), especially water absorption and solubility indexes, sectional expansion ratio, bulk density, color and specific mechanical energy. The interaction term of feed rate and temperature, and square term of screw speed had no significant influences (p ≥ 0.1). The findings were useful for developing and optimizing extruded or value-added co products of breadfruit.     

Interspecific Comparison of Constitutive Ash Phloem Phenolic Chemistry Reveals Compounds Unique to Manchurian Ash, a Species Resistant to Emerald Ash Borer

The emerald ash borer (Agrilus planipennis, EAB) is an invasive wood-borer indigenous to Asia and is responsible for widespread ash (Fraxinus spp.) mortality in the U.S. and Canada. Resistance and susceptibility to EAB varies among Fraxinus spp., which is a result of their co-evolutionary history with the pest. We characterized constitutive phenolic profiles and lignin levels in the phloem of green, white, black, blue, European, and Manchurian ash. Phloem was sampled twice during the growing season, coinciding with phenology of early and late instar EAB. We identified 66 metabolites that displayed a pattern of variation, which corresponded strongly with phylogeny. Previously identified lignans and lignan derivatives were confirmed to be unique to Manchurian ash, and may contribute to its high level of resistance to EAB. Other compounds that had been considered unique to Manchurian ash, including hydroxycoumarins and the phenylethanoids calceolarioside A and B, were detected in closely related, but susceptible species, and thus are unlikely to contribute to EAB resistance of Manchurian ash. The distinct phenolic profile of blue ash may contribute to its relatively high resistance to EAB.     

Investigation of Scents on Cheeks and Foreheads of Large Felines in Connection to the Facial Marking Behavior

We investigated head- and cheek-rubbing behavior in four species of large felines, lions (Leo panther), leopards (Panthera pardus), tigers (Panthera tigris), and cougars (Puma concolor), in captivity. Preliminary behavioral observations found that lions and tigers, but not leopards and cougars, showed behavioral responses to cardboard rubbing samples from head and cheek areas from conspecific felines, compared to the blank cardboard controls. In this context, surface samples on the facial areas of each species were collected to analyze volatile organic compounds that could be involved in the facial marking of felines. Previously developed stir bar surface sampling methodology was used. From all cheek and forehead samples, 100 volatile organic compounds were identified or tentatively identified. Among these, 41 have been previously reported to be present in feline urine and marking secretions. Several new compounds were identified on facial surfaces. Some of the compounds showed substantial quantitative differences among the species. One compound, that has not been reported previously in mammals, 3-acetamidofuran, was found in all investigated species. It was synthesized and tested for behavioral responses. No responses were elicited in a preliminary test. Future research will test other potential signaling compounds and their mixtures for ability to elicit behavioral responses.     

Maximizing Parallel Testing in an FM Receiver

High volume production environments create great challenges for production testing and verification of Radio Frequency (RF) devices. In this environment, much emphasis is put on parallel testing, or the ability to test multiple devices at the same time using a single tester. In order for this parallelism to become a reality, there is a need for production RF tests to be simplified and reduced to requiring only the simplest test stimulus and analysis. In this paper, we present a new method of measuring the performance of a Frequency Modulation (FM) receiver that requires only a continuous wave signal input in order to eliminate the more costly Signal-to-Noise Ratio test. Using this new technique we will then demonstrate how simplifying this test and adding frequency diversity enables testing of up to 8 devices in parallel using a single tester.     

The role of heat in rubbing and massage-related corneal deformation

PurposeTo examine the role of elevated corneal temperature in the development of rubbing/massage-related corneal deformation and the possibility that warm compresses in the management of meibomian gland dysfunction or chalazion could contribute to such adverse responses.MethodsWith reference to reports of corneal deformation associated with meibomian gland dysfunction, chalazion, dacryocystoceles and post-trabeculectomy, the mechanisms for increased corneal temperature due to ocular massage, especially when combined with warm compresses are examined.ResultsSeveral mechanisms for rubbing/massage to elevate corneal temperature have been described, apart from the application of warm compresses or other forms of heat.ConclusionsRaised corneal temperature helps to explain corneal deformation which develops in association with rubbing or massage in conditions such as keratoconus, chalazion, post-trabeculectomy, post-laser assisted in situ keratomileusis, post-graft and dacryocystoceles. When combined with warm compresses or other methods of heat delivery to the eye, the elevation of corneal temperature appears to explain how meibomian gland dysfunction treatment involving warm compresses and massage could induce rubbing-related deformation. Patients whose management involves iatrogenic ocular massage appear to require screening for risk of corneal deformation. Risk may be increased for patients with a concurrent habit of rubbing their eyes abnormally in response to allergic itch for example. It appears to be possible to modify ocular massage techniques to reduce the risk of corneal deformation. Careful tutoring and follow-up using corneal topography appears to be required when massage is prescribed, especially when used in conjunction with heat application.     

Biomimetic Membrane System Composed of a Composite Interpenetrating Hydrogel Film and a Lipid Bilayer

A simple way to form an interpenetrating hydrogel (IPH) by combining a layer‐by‐layer polyelectrolyte membrane with agarose is reported. The formed IPH membrane is more robust and easily manipulated compared to a polyelectrolyte membrane with the same number of layers. The IPH has good diffusion characteristics and retains the advantageous surface charge from the polyectrolyte composition that facilitates the adsorption of a stable lipid bilayer. The stable adsorption of a lipid bilayer on the IPH creates a biomimetic membrane system that is optimized for utilization in a diffusion chamber.