381 research outputs found
Our rivals : The molds, yeasts and bacteria.
In this day when the erstwhile plebian hog has taken to scaling the social ladder and has climbed beyond the ken of many an honest workman, it behooves the housewife to wage, with double zeal the warfare on our rivals, the molds, yeasts and bacteria who come as unbidden guests eating the very food that we must have, raising enormous families at our expense, frequently making themselves obnoxious as long as the food lasts, then quietly withdrawing into themselves and either waiting for a fresh supply of food or allowing the housewife to start them by the dust-brush route to a new larder
Oxygenated Aromatic Compounds are Important Precursors of Secondary Organic Aerosol in Biomass Burning Emissions
Biomass burning is the largest combustion-related source of volatile organic compounds (VOCs) to the atmosphere. We describe the development of a state-of-the-science model to simulate the photochemical formation of secondary organic aerosol (SOA) from biomass-burning emissions observed in dry (RH <20%) environmental chamber experiments. The modeling is supported by (i) new oxidation chamber measurements, (ii) detailed concurrent measurements of SOA precursors in biomass-burning emissions, and (iii) development of SOA parameters for heterocyclic and oxygenated aromatic compounds based on historical chamber experiments. We find that oxygenated aromatic compounds, including phenols and methoxyphenols, account for slightly less than 60% of the SOA formed and help our model explain the variability in the organic aerosol mass (RΒ² = 0.68) and O/C (RΒ² = 0.69) enhancement ratios observed across 11 chamber experiments. Despite abundant emissions, heterocyclic compounds that included furans contribute to βΌ20% of the total SOA. The use of pyrolysis-temperature-based or averaged emission profiles to represent SOA precursors, rather than those specific to each fire, provide similar results to within 20%. Our findings demonstrate the necessity of accounting for oxygenated aromatics from biomass-burning emissions and their SOA formation in chemical mechanisms
Distribution, magnitudes, reactivities, ratios and diurnal patterns of volatile organic compounds in the Valley of Mexico during the MCMA 2002 and 2003 field campaigns
International audienceA wide array of volatile organic compound (VOC) measurements was conducted in the Valley of Mexico during the MCMA-2002 and 2003 field campaigns. Study sites included locations in the urban core, in a heavily industrial area and at boundary sites in rural landscapes. In addition, a novel mobile-laboratory-based conditional sampling method was used to collect samples dominated by fresh on-road vehicle exhaust to identify those VOCs whose ambient concentrations were primarily due to vehicle emissions. Five distinct analytical techniques were used: whole air canister samples with Gas Chromatography/Flame Ionization Detection (GC-FID), on-line chemical ionization using a Proton Transfer Reaction Mass Spectrometer (PTR-MS), continuous real-time detection of olefins using a Fast Olefin Sensor (FOS), and long path measurements using UV Differential Optical Absorption Spectrometers (DOAS). The simultaneous use of these techniques provided a wide range of individual VOC measurements with different spatial and temporal scales. The VOC data were analyzed to understand concentration and spatial distributions, diurnal patterns, origin and reactivity in the atmosphere of Mexico City. The VOC burden (in ppbC) was dominated by alkanes (60%), followed by aromatics (15%) and olefins (5%). The remaining 20% was a mix of alkynes, halogenated hydrocarbons, oxygenated species (esters, ethers, etc.) and other unidentified VOCs. However, in terms of ozone production, olefins were the most relevant hydrocarbons. Elevated levels of toxic hydrocarbons, such as 1,3-butadiene, benzene, toluene and xylenes were also observed. Results from these various analytical techniques showed that vehicle exhaust is the main source of VOCs in Mexico City and that diurnal patterns depend on vehicular traffic. Finally, examination of the VOC data in terms of lumped modeling VOC classes and its comparison to the VOC lumped emissions reported in other photochemical air quality modeling studies suggests that some, but not all, VOC classes are underestimated in the emissions inventory by factors of 1.1 to 3
Distribution, magnitudes, reactivities, ratios and diurnal patterns of volatile organic compounds in the Valley of Mexico during the MCMA 2002 & 2003 field campaigns
A wide array of volatile organic compound (VOC) measurements was conducted in the Valley of Mexico during the MCMA-2002 and 2003 field campaigns. Study sites included locations in the urban core, in a heavily industrial area and at boundary sites in rural landscapes. In addition, a novel mobile-laboratory-based conditional sampling method was used to collect samples dominated by fresh on-road vehicle exhaust to identify those VOCs whose ambient concentrations were primarily due to vehicle emissions. Four distinct analytical techniques were used: whole air canister samples with Gas Chromatography/Flame Ionization Detection (GC-FID), on-line chemical ionization using a Proton Transfer Reaction Mass Spectrometer (PTR-MS), continuous real-time detection of olefins using a Fast Olefin Sensor (FOS), and long path measurements using UV Differential Optical Absorption Spectrometers (DOAS). The simultaneous use of these techniques provided a wide range of individual VOC measurements with different spatial and temporal scales. The VOC data were analyzed to understand concentration and spatial distributions, diurnal patterns, origin and reactivity in the atmosphere of Mexico City. The VOC burden (in ppbC) was dominated by alkanes (60%), followed by aromatics (15%) and olefins (5%). The remaining 20% was a mix of alkynes, halogenated hydrocarbons, oxygenated species (esters, ethers, etc.) and other unidentified VOCs. However, in terms of ozone production, olefins were the most relevant hydrocarbons. Elevated levels of toxic hydrocarbons, such as 1,3-butadiene, benzene, toluene and xylenes, were also observed. Results from these various analytical techniques showed that vehicle exhaust is the main source of VOCs in Mexico City and that diurnal patterns depend on vehicular traffic in addition to meteorological processes. Finally, examination of the VOC data in terms of lumped modeling VOC classes and its comparison to the VOC lumped emissions reported in other photochemical air quality modeling studies suggests that some alkanes are underestimated in the emissions inventory, while some olefins and aromatics are overestimated
Π‘ΡΠ°ΡΠ΅Π²Ρ ΠΎΡΠΎΠ±Π»ΠΈΠ²ΠΎΡΡΡ ΠΌΠ΅ΡΠ°Π±ΠΎΠ»ΡΠ·ΠΌΡ ΠΌΡΠΎΠΊΠ°ΡΠ΄Π° Π² Π΄ΠΈΠ½Π°ΠΌΡΡΡ ΡΠΎΠ·Π²ΠΈΡΠΊΡ Π΅ΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½ΡΠ°Π»ΡΠ½ΠΎΠ³ΠΎ Π³ΡΠΏΠ΅ΡΡΠΈΡΠ΅ΠΎΠ·Ρ
Π ΡΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½ΡΠ°Ρ
Π½Π° ΠΏΠΎΠ»ΠΎΠ²ΠΎΠ·ΡΠ΅Π»ΡΡ
ΡΠ°ΠΌΡΠ°Ρ
ΠΈ ΡΠ°ΠΌΠΊΠ°Ρ
ΠΊΡΡΡ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΎ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ ΠΏΠ΅ΡΠ΅ΠΊΠΈΡΠ½ΠΎΠ³ΠΎ ΠΎΠΊΠΈΡΠ»Π΅Π½Π½Ρ Π»ΠΈΠΏΠΈΠ΄ΠΎΠ², Π°Π½ΡΠΈΠΎΠΊΡΠΈΠ΄Π°Π½ΡΠ½ΠΎΠΉ Π·Π°ΡΠΈΡΡ ΠΈ ΡΠ½Π΅ΡΠ³ΠΎΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΡ Π² Π΄ΠΈΠ½Π°ΠΌΠΈΠΊΠ΅ ΡΠ°Π·Π²ΠΈΡΠΈΡ ΡΠΈΡΠΎΠΊΡΠΈΠ½ΠΎΠ²ΠΎΠΉ ΠΊΠ°ΡΠ΄ΠΈΠΎΠΌΠΈΠΎΠΏΠ°ΡΠΈΠΈ, ΠΊΠΎΡΠΎΡΡΡ ΠΌΠΎΠ΄Π΅Π»ΠΈΡΠΎΠ²Π°Π»ΠΈ Π²Π²Π΅Π΄Π΅Π½ΠΈΠ΅ΠΌ L-ΡΠΈΡΠΎΠΊΡΠΈΠ½Π° (500 ΠΌΠ³/ΠΊΠ³, Π²Π½ΡΡΡΠΈΠΆΠ΅Π»ΡΠ΄ΠΎΡΠ½ΠΎ, Π΅ΠΆΠ΅Π΄Π½Π΅Π²Π½ΠΎ). Π ΠΌΠΈΠΎΠΊΠ°ΡΠ΄Π΅ ΠΆΠ΅Π»ΡΠ΄ΠΎΡΠΊΠΎΠ² ΡΠ΅ΡΠ΅Π· 5, 10 ΠΈ 15 Π΄Π½Π΅ΠΉ Ρ Π½Π°ΡΠ°Π»Π° ΡΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½ΡΠ° ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΠ»ΠΈ ΡΠΎΠ΄Π΅ΡΠΆΠ°Π½ΠΈΠ΅ Π΄ΠΈΠ΅Π½ΠΎΠ²ΡΡ
ΠΈ ΡΡΠΈΠ΅Π½ΠΎΠ²ΡΡ
ΠΊΠΎΠ½ΡΡΠ³Π°Ρ (ΠΠ, Π’Π), Π’ΠΠ-Π°ΠΊΡΠΈΠ²Π½ΡΡ
ΠΏΡΠΎΠ΄ΡΠΊΡΠΎΠ² (Π’ΠΠ-ΠΠ), Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ ΡΡΠΏΠ΅ΡΠΎΠΊΡΠΈΠ΄Π΄ΠΈΡΠΌΡΡΠ°Π·Ρ (Π‘ΠΠ), ΠΊΠ°ΡΠ°Π»Π°Π·Ρ, Π³Π»ΡΡΠ°ΡΠΈΠΎΠ½ΠΏΠ΅ΡΠΎΠΊΡΠΈΠ΄Π°Π·Ρ (ΠΠ) ΠΈ Π³Π»ΡΡΠ°ΡΠΈΠΎΠ½ΡΠ΅Π΄ΡΠΊΡΠ°Π·Ρ (ΠΠ ), ΡΡΠΊΡΠΈΠ½Π°ΡΠ΄Π΅Π³ΠΈΠ΄ΡΠΎΠ³Π΅Π½Π°Π·Ρ (Π‘ΠΠ), ΡΠΈΡΠΎΡ
ΡΠΎΠΌΠΎΠΊΡΠΈΠ΄Π°Π·Ρ (Π¦Π). Π£ΡΡΠ°Π½ΠΎΠ²ΠΈΠ»ΠΈ, ΡΡΠΎ Π³ΠΈΠΏΠ΅ΡΡΠΈΡΠΎΠΊΡΠΈΠ½Π΅ΠΌΠΈΡ Π²ΠΈΠ·ΡΠ²Π°Π»Π° Π½Π°ΠΊΠΎΠΏΠ»Π΅Π½ΠΈΠ΅ Π² ΠΌΠΈΠΎΠΊΠ°ΡΠ΄Π΅ ΠΆΠ΅Π»ΡΠ΄ΠΎΡΠΊΠΎΠ² ΠΊΡΡΡ ΠΠ, Π’Π ΠΈ Π’ΠΠ-ΠΠ, ΡΡΠΎ Π² ΡΠ°ΠΌΠΎΠΊ Π±ΡΠ»ΠΎ Π±ΠΎΠ»Π΅Π΅ ΡΡΡΠ΅ΡΡΠ²Π΅Π½Π½ΡΠΌ, ΡΠ΅ΠΌ Ρ ΡΠ°ΠΌΡΠΎΠ², Π½Π΅ΡΠΌΠΎΡΡΡ Π½Π° Π±ΠΎΠ»ΡΡΡΡ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ ΠΠ ΡΠ° ΠΠ . ΠΠ΅Π΄ΠΎΡΡΠ°ΡΠΎΡΠ½Π°Ρ ΠΏΡΠΎΡΠ΅ΠΊΡΠΎΡΠ½Π°Ρ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ ΡΠ΅ΡΠΌΠ΅Π½ΡΠΎΠ² ΡΠΈΡΡΠ΅ΠΌΡ Π³Π»ΡΡΠ°ΡΠΈΠΎΠ½Π° Π±ΡΠ»Π° ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΠΎΠΌ Π·Π½Π°ΡΠΈΡΠ΅Π»ΡΠ½ΠΎΠ³ΠΎ ΡΠ³Π½Π΅ΡΠ΅Π½ΠΈΡ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΠΈ Π‘ΠΠ ΠΈ ΠΊΠ°ΡΠ°Π»Π°Π·Ρ, ΡΡΠΎ ΡΠ²ΠΈΠ΄Π΅ΡΠ΅Π»ΡΡΡΠ²ΠΎΠ²Π°Π»ΠΎ ΠΎ ΡΡΡΠ΅ΡΡΠ²Π΅Π½Π½ΠΎΠΌ Π½Π°ΠΊΠΎΠΏΠ»Π΅Π½ΠΈΠΈ Π°ΠΊΡΠΈΠ²Π½ΡΡ
ΡΠΎΡΠΌ ΠΊΠΈΡΠ»ΠΎΡΠΎΠ΄Π°. ΠΠΊΡΠΈΠ²Π½ΠΎΡΡΡ ΡΠ½Π΅ΡΠ³ΠΎΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΡ Π² ΡΠ°ΠΊΠΈΡ
ΡΡΠ»ΠΎΠ²ΠΈΡΡ
ΡΠΌΠ΅Π½ΡΡΠ°Π»Π°ΡΡ, ΠΎ ΡΠ΅ΠΌ ΡΠ²ΠΈΠ΄Π΅ΡΠ΅Π»ΡΡΡΠ²ΠΎΠ²Π°Π»ΠΎ ΡΠ³Π½Π΅ΡΠ΅Π½ΠΈΠ΅ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΠΈ Π‘ΠΠ, ΠΊΠΎΡΠΎΡΠΎΠ΅ Π±ΡΠ»ΠΎ Π°Π½Π°Π»ΠΎΠ³ΠΈΡΠ½ΡΠΌ Π² ΡΠ°ΠΌΡΠΎΠ² ΠΈ ΡΠ°ΠΌΠΎΠΊ, ΠΈ Π¦Π, ΡΡΠΎ Π±ΡΠ»ΠΎ Π±ΠΎΠ»Π΅Π΅ ΡΡΡΠ΅ΡΡΠ²Π΅Π½Π½ΡΠΌ Π² ΡΠ°ΠΌΠΎΠΊ. ΠΠΎΠ»ΡΡΠ΅Π½Π½ΡΠ΅ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΡ ΡΠ²ΠΈΠ΄Π΅ΡΠ΅Π»ΡΡΡΠ²ΡΡΡ ΠΎ ΡΠΎΠΌ, ΡΡΠΎ ΡΠ°Π·Π²ΠΈΡΠΈΠ΅ ΡΠΈΡΠΎΠΊΡΠΈΠ½ΠΎΠ²ΠΎΠΉ ΠΊΠ°ΡΠ΄ΠΈΠΎΠΌΠΈΠΎΠΏΠ°ΡΠΈΠΈ Π²ΡΠ·ΡΠ²Π°Π΅Ρ ΡΡΡΠ΅ΡΡΠ²Π΅Π½Π½ΡΠΉ ΠΌΠ΅ΡΠ°Π±ΠΎΠ»ΠΈΡΠ΅ΡΠΊΠΈΠΉ Π΄ΠΈΡΠ±Π°Π»Π°Π½Ρ Π² ΠΌΠΈΠΎΠΊΠ°ΡΠ΄Π΅ ΠΆΠ΅Π»ΡΠ΄ΠΎΡΠΊΠΎΠ² ΡΠ°ΠΌΠΎΠΊ ΠΊΡΡΡ, ΡΡΠΎ ΡΠ°Π·ΡΠ΅ΡΠ°Π΅Ρ ΠΎΠΆΠΈΠ΄Π°ΡΡ Π±ΠΎΠ»Π΅ΠΌ ΠΈΠ½ΡΠ΅Π½ΡΠΈΠ²Π½ΡΠ΅ ΡΡΡΡΠΊΡΡΡΠ½ΡΠ΅ Π½Π°ΡΡΡΠ΅Π½ΠΈΡ.Lipid peroxidation, antioxidant protection and energy production were studied in adult male and female rats with thyroxin cardiomyopathy, which simulated by introduction of L-thyroxine (500 mg / kg, intraperitoneally, daily). In the myocardium of the ventricles after 5, 10 and 15 days from the start of the experiment determined the content of diene and triene conjugate (DC, TC), TBA-active metabolits (TBA-am), activity of superoxide dismutase (SOD), catalase, glutathione peroxidase (GP) and glutathione reductase (GR), succinate dehydrogenase (SDH), cytochrome oxidase (CO). Found that hyperthyroxinemia caused accumulation in myocardium of the ventricles DC, TC and TBA-am mostly in females despite the higher activity of GP and GR. Lack of protective effects of glutathione system enzymes resulted from significant inhibition of SOD and catalase, indicating a significant accumulation of reactive species of oxygen. Activity of the energy production in these conditions decreased. That was proved by the inhibition of SDH in myocardium both sex animals and CO mostly in females. We conclude that the development of thyroxin cardiomyopathy causes metabolic disbalance in myocardium of the ventricles mostly in female rats, which can results in more intense structural damage
Alternative Aviation Fuel Experiment (AAFEX)
The rising cost of oil coupled with the need to reduce pollution and dependence on foreign suppliers has spurred great interest and activity in developing alternative aviation fuels. Although a variety of fuels have been produced that have similar properties to standard Jet A, detailed studies are required to ascertain the exact impacts of the fuels on engine operation and exhaust composition. In response to this need, NASA acquired and burned a variety of alternative aviation fuel mixtures in the Dryden Flight Research Center DC-8 to assess changes in the aircraft s CFM-56 engine performance and emission parameters relative to operation with standard JP-8. This Alternative Aviation Fuel Experiment, or AAFEX, was conducted at NASA Dryden s Aircraft Operations Facility (DAOF) in Palmdale, California, from January 19 to February 3, 2009 and specifically sought to establish fuel matrix effects on: 1) engine and exhaust gas temperatures and compressor speeds; 2) engine and auxiliary power unit (APU) gas phase and particle emissions and characteristics; and 3) volatile aerosol formation in aging exhaust plume
Predicting Inactive Conformations of Protein Kinases Using Active Structures: Conformational Selection of Type-II Inhibitors
Protein kinases have been found to possess two characteristic conformations in their activation-loops: the active DFG-in conformation and the inactive DFG-out conformation. Recently, it has been very interesting to develop type-II inhibitors which target the DFG-out conformation and are more specific than the type-I inhibitors binding to the active DFG-in conformation. However, solving crystal structures of kinases with the DFG-out conformation remains a challenge, and this seriously hampers the application of the structure-based approaches in development of novel type-II inhibitors. To overcome this limitation, here we present a computational approach for predicting the DFG-out inactive conformation using the DFG-in active structures, and develop related conformational selection protocols for the uses of the predicted DFG-out models in the binding pose prediction and virtual screening of type-II ligands. With the DFG-out models, we predicted the binding poses for known type-II inhibitors, and the results were found in good agreement with the X-ray crystal structures. We also tested the abilities of the DFG-out models to recognize their specific type-II inhibitors by screening a database of small molecules. The AUC (area under curve) results indicated that the predicted DFG-out models were selective toward their specific type-II inhibitors. Therefore, the computational approach and protocols presented in this study are very promising for the structure-based design and screening of novel type-II kinase inhibitors
A Three Species Model to Simulate Application of Hyperbaric Oxygen Therapy to Chronic Wounds
Chronic wounds are a significant socioeconomic problem for governments worldwide. Approximately 15% of people who suffer from diabetes will experience a lower-limb ulcer at some stage of their lives, and 24% of these wounds will ultimately result in amputation of the lower limb. Hyperbaric Oxygen Therapy (HBOT) has been shown to aid the healing of chronic wounds; however, the causal reasons for the improved healing remain unclear and hence current HBOT protocols remain empirical. Here we develop a three-species mathematical model of wound healing that is used to simulate the application of hyperbaric oxygen therapy in the treatment of wounds. Based on our modelling, we predict that intermittent HBOT will assist chronic wound healing while normobaric oxygen is ineffective in treating such wounds. Furthermore, treatment should continue until healing is complete, and HBOT will not stimulate healing under all circumstances, leading us to conclude that finding the right protocol for an individual patient is crucial if HBOT is to be effective. We provide constraints that depend on the model parameters for the range of HBOT protocols that will stimulate healing. More specifically, we predict that patients with a poor arterial supply of oxygen, high consumption of oxygen by the wound tissue, chronically hypoxic wounds, and/or a dysfunctional endothelial cell response to oxygen are at risk of nonresponsiveness to HBOT. The work of this paper can, in some way, highlight which patients are most likely to respond well to HBOT (for example, those with a good arterial supply), and thus has the potential to assist in improving both the success rate and hence the cost-effectiveness of this therapy
Rapid deacetylation of yeast Hsp70 mediates the cellular response to heat stress
Hsp70 is a highly conserved molecular chaperone critical for the folding of new and denatured proteins. While traditional models state that cells respond to stress by upregulating inducible HSPs, this response is relatively slow and is limited by transcriptional and translational machinery. Recent studies have identified a number of post-translational modifications (PTMs) on Hsp70 that act to fine-tune its function. We utilized mass spectrometry to determine whether yeast Hsp70 (Ssa1) is differentially modified upon heat shock. We uncovered four lysine residues on Ssa1, K86, K185, K354 and K562 that are deacetylated in response to heat shock. Mutation of these sites cause a substantial remodeling of the Hsp70 interaction network of co-chaperone partners and client proteins while preserving essential chaperone function. Acetylation/deacetylation at these residues alter expression of other heat-shock induced chaperones as well as directly influencing Hsf1 activity. Taken together our data suggest that cells may have the ability to respond to heat stress quickly though Hsp70 deacetylation, followed by a slower, more traditional transcriptional response
- β¦