-
PloS One 2019In recent years, with the rapid development of China's air transport industry and the change in market consumption structure, service quality has become one of the...
In recent years, with the rapid development of China's air transport industry and the change in market consumption structure, service quality has become one of the important factors affecting airline revenue. How to formulate a reasonable pricing strategy and maintain competitiveness in the fierce market competition has become an urgent problem for airlines. First, the impact factor of service quality level in the traditional pricing model is introduced and a static price competition model for multi-oligopoly airlines based on service quality is established in this paper. And then, a dynamic pricing model based on service quality of the multi-oligopoly airlines is established. The model incorporates the weight factor of service quality impact, which is used to indicate the weight of the service quality level in the process of airline dynamic pricing. The research results show that the service quality level of airlines has an indispensable influence on its development. Airlines should improve service quality as soon as possible to enhance market competitiveness and achieve sustainable development.
Topics: Air; Costs and Cost Analysis; Models, Economic; Quality Control; Transportation
PubMed: 31206535
DOI: 10.1371/journal.pone.0216651 -
Chemosphere May 2019In Washington State, half of all pesticide-related illnesses in agriculture result from drift, the off-target movement of pesticides. Of these, a significant proportion...
In Washington State, half of all pesticide-related illnesses in agriculture result from drift, the off-target movement of pesticides. Of these, a significant proportion involve workers on another farm and orchard airblast applications. We compared the spray drift exposure reduction potential of two modern tower sprayers - directed air tower (DAT) and multi-headed fan tower (MFT), in relation to a traditional axial fan airblast (AFA) sprayer. We employed real-time particle monitors (Dylos DC1100) during a randomized control trial of orchard spray applications. Sections of a field were randomly sprayed by three alternating spray technologies - AFA, DAT and MFT - while monitors sampled particulate matter above and below the canopy at various downwind locations in a neighboring field. Geometric mean particle mass concentrations (PMC) outside the intended spray area were elevated during all applications at all of our sampling distances (16-74 m, 51-244 ft). After adjusting for wind speed and sampling height, the 75th percentile (95% confidence interval) PMC level was significantly greater during spray events than background levels by 105 (93, 120) μg/m, 49 (45, 54) μg/m and 26 (22, 31) μg/m during AFA, DAT and MFT applications, respectively. Adjusted PMC levels were significantly different between all three sprayers. In this study, tower sprayers significantly reduced spray drift exposures in a neighboring orchard field when compared to the AFA sprayer, with the MFT sprayer producing the least drift; however these tower sprayers did do not fully eliminate drift.
Topics: Agriculture; Air Movements; Air Pollutants; Environmental Monitoring; Particulate Matter; Pesticides; Technology; Washington; Wind
PubMed: 30690400
DOI: 10.1016/j.chemosphere.2019.01.092 -
The Analyst Jan 2021A micro fabricated chip-based wearable air sampler was used to monitor the personnel exposure of volatile chemical concentrations in microenvironments. Six teenagers...
A micro fabricated chip-based wearable air sampler was used to monitor the personnel exposure of volatile chemical concentrations in microenvironments. Six teenagers participated in this study and 14 volatile organic compounds (VOCs) including naphthalene, 3-decen-1-ol, hexanal, nonanal, methyl salicylate and limonene gave the highest abundance during routine daily activity. VOC exposure associated with daily activities and the location showed strong agreements with two of the participant's results. One of these subjects had the highest exposure to methyl salicylate that was supported by the use of a topical analgesic balm containing this compound. Environmental based air quality monitoring followed by the personnel exposure studies provided additional evidence associated to the main locations where the participants traveled. Toluene concentrations observed at a gas station were exceptionally high, with the highest amount observed at 1213.1 ng m. One subject had the highest exposure to toluene and the GPS data showed clear evidence of activities neighboring a gas station. This study shows that this wearable air sampler has potential applications including hazardous VOC exposure monitoring in occupational hazard assessment for certain professions, for example in industries that involve direct handling of petroleum products.
Topics: Air; Environmental Exposure; Gas Chromatography-Mass Spectrometry; Humans; Volatile Organic Compounds
PubMed: 33205787
DOI: 10.1039/d0an01521k -
BioMed Research International 2013Pollutant emissions and their contribution to local and regional air quality at the industrial area of Tula were studied during a four-week period as part of the MILAGRO...
Pollutant emissions and their contribution to local and regional air quality at the industrial area of Tula were studied during a four-week period as part of the MILAGRO initiative. A recurrent shallow stable layer was observed in the morning favoring air pollutants accumulation in the lower 100 m atmospheric layer. In the afternoon the mixing layer height reached 3000 m, along with a featuring low level jet which was responsible of transporting air pollutants at regional scales. Average PM10 at Jasso (JAS) and Tepeji (TEP) was 75.1 and 36.8 μ g/m(3), respectively while average PM2.5 was 31.0 and 25.7 μ g/m(3). JAS was highly impacted by local limestone dust, while TEP was a receptor of major sources of combustion emissions with 70% of the PM10 constituted by PM2.5. Average hourly aerosol light absorption was 22 Mm(-1), while aerosol scattering (76 Mm(-1)) was higher compared to a rural site but much lower than at Mexico City. δ(13)C values in the epiphyte Tillandsia recurvata show that the emission plume directly affects the SW sector of Mezquital Valley and is then constrained by a mountain range preventing its dispersion. Air pollutants may exacerbate acute and chronic adverse health effects in this region.
Topics: Air; Air Pollutants; Industry; Mexico; Tillandsia
PubMed: 23484131
DOI: 10.1155/2013/521728 -
Poultry Science Sep 2010Egg storage beyond 7 d is associated with an increase in incubation duration and a decrease in hatchability and chick quality. Negative effects of prolonged egg storage...
Egg storage beyond 7 d is associated with an increase in incubation duration and a decrease in hatchability and chick quality. Negative effects of prolonged egg storage may be caused by changes in the embryo, by changes in egg characteristics, or by both. An adjustment in storage air composition may reduce negative effects of prolonged egg storage because it may prevent changes in the embryo and in egg characteristics. An experiment was conducted to investigate the effects of high CO(2) concentrations or a low O(2) concentration in the storage air on egg characteristics, embryonic development, hatchability, and chick quality. Eggs were stored for 14 d in 4 different storage air compositions: normal air (control; 20.9% O(2), 0.05% CO(2), 78.1% N(2)), 0.74% CO(2) treatment (20.8% O(2), 0.74% CO(2), 77.5% N(2)), 1.5% CO(2) treatment (20.6% O(2), 1.5% CO(2), 77.0% N(2))(,) or 3.0% O(2) treatment (3.0% O(2), 0.04% CO(2), 96.0% N(2)). The storage temperature was 16 degrees C and the RH was 75%. Results showed that the change in albumen pH and albumen height between oviposition and the end of storage was less in the 0.74 and 1.5% CO(2) treatments than in the control and 3.0% O(2) treatments (P < 0.001 and P < 0.001, respectively). None of the treatments affected the stage of embryonic development on d 4 of incubation, hatchability, or chick quality on the day of hatch in terms of BW, chick length, and yolk-free body mass. Although high CO(2) concentrations in the storage air had a positive effect on albumen height and albumen pH, it is concluded that the storage air compositions, studied in the current study, do not affect embryonic development, hatchability, or chick quality when eggs are stored for 14 d at a storage temperature of 16 degrees C.
Topics: Air; Albumins; Animal Husbandry; Animals; Chick Embryo; Chickens; Female; Male; Ovum; Time Factors
PubMed: 20709986
DOI: 10.3382/ps.2009-00610 -
Journal of Chromatography. A Jul 2019The applicability of an aerial drone as a carrier for new passive and active miniaturized air sampling systems, including solid phase microextration Arrow (SPME Arrow)...
The applicability of an aerial drone as a carrier for new passive and active miniaturized air sampling systems, including solid phase microextration Arrow (SPME Arrow) and in-tube extraction (ITEX), was studied in this research. Thermal desorption, gas chromatography and mass spectrometry were used for the determination of volatile organic compounds (VOCs) collected by the sampling systems. The direct comparison of the profiles of VOCs, simultaneously sampled in air by SPME Arrow system including four different coatings, allowed the elucidation of their adsorption selectivity. A more complex experimental design, involving 20 samples (10 flights) and non-supervised pattern recognition techniques, was needed for the clarification of the same sampling parameters in the case of five ITEX sorbent materials. In addition, ITEX sampling accessories, such as particle, water and ozone traps, were evaluated by comparing the results obtained for air samples simultaneously collected by two ITEX systems, packed with the same sorbent and furnished or not with sampling accessories. The effect of the aerial drone horizontal displacement (HD) on the sampling efficiency was clear in the case of SPME Arrow. The number of detected compounds and their relative peak area values (RPA) revealed a clear increase (4 and 43%, respectively) in comparison with samples collected without drone HD. However, just minor differences were observed in the case of ITEX (2 compounds and 9% of the ∑RPA). In addition, the system was able to provide almost simultaneous passive (SPME Arrow) and active (ITEX) samplings at different altitudes (5 and 50 m), being a good tool for low cost vertical profiling studies (∑RPA decreased over 35% for the samples collected at 50 m). Finally, the successful simultaneous air sampling by SPME Arrow and ITEX systems in two difficult access places, such as boreal forest and wetlands, was demonstrated, resulting in 21 and 31 detected compounds in forest and wetlands by SPME Arrow, and 27 and 39 compounds by ITEX.
Topics: Adsorption; Air; Environmental Monitoring; Gas Chromatography-Mass Spectrometry; Miniaturization; Solid Phase Microextraction; Volatile Organic Compounds
PubMed: 31030954
DOI: 10.1016/j.chroma.2019.04.009 -
Dental Materials Journal 2013The purpose was to evaluate the effect of air-blowing duration of three different adhesive systems on immediate or thermal aged resin-dentin shear bond strength (SBS)....
The purpose was to evaluate the effect of air-blowing duration of three different adhesive systems on immediate or thermal aged resin-dentin shear bond strength (SBS). Human dentin surfaces were bonded with: one-step (Bond Force, BF), two-step (FL-Bond II, FLB) and three-step (Scotch Bond Multi-Purpose, SBMP) adhesive systems. Bonded surfaces from each group were air-blown for 0, 5, or 10 s and cured. Composite cylinders were built on the treated surfaces and cured. Half of the specimens from each group were tested immediately and the other halves were tested after thermal aging. Statistical analysis showed significant decrease in SBS after thermal aging compared to immediate testing in all groups, except BF after 5 s air-blowing or FLB and SBMP with no air-blowing (p>0.05). The results suggested that 5 s air-blowing is necessary to obtain a stable SBS for BF. However, extended airblowing duration of FLB and SBMP decreased the SBS significantly after thermal aging.
Topics: Air; Dental Cements; Dentin; Materials Testing; Microscopy, Electron, Scanning; Temperature
PubMed: 24088832
DOI: 10.4012/dmj.2013-026 -
Chemosphere Sep 2009A Teflon dynamic flux chamber was used to characterize Gaseous Elemental Mercury (GEM) flux from forested and open field soils in a highly changing environment in...
A Teflon dynamic flux chamber was used to characterize Gaseous Elemental Mercury (GEM) flux from forested and open field soils in a highly changing environment in Rondônia State, western Amazon. We simultaneously analyzed meteorological parameters at the soil level relating GEM fluxes to soil temperature, air humidity, soil moisture, solar radiation, and speed and wind direction. We also examined variations of atmospheric GEM concentration. GEM fluxes during the day and night in the open field site were significantly different (17+/-14ngm(-2) h(-1) and 0.9+/-1.9ngm(-2)h(-1), for day and night, respectively), but were similar within the forest site (4.8+/-1.4ngm(-2)h(-1) and 4.4+/-1.8ngm(-2) h(-1) for day and night periods, respectively). A comparison between 24-h periods averages in the two sites showed much larger emission from the open field site. GEM fluxes at the open field site were positively correlated with soil moisture, solar irradiation and soil temperature and inversely correlated with air humidity. At the forest site GEM fluxes showed no correlation with meteorological variables. At the open field site GEM concentrations significantly correlated with GEM flux, at least during the day. At night in the open field site and during the day and night at the forest site no correlation was found between GEM fluxes and GEM concentrations in the ambient air. Higher emissions from the open field site support earlier studies showing larger Hg remobilization following forest conversion to pasture.
Topics: Air; Brazil; Gases; Humidity; Mercury; Soil; Soil Pollutants; Solar Energy; Temperature; Time Factors; Trees; Wind
PubMed: 19555993
DOI: 10.1016/j.chemosphere.2009.05.018 -
Scientific Reports Oct 2017Vegetation cover is crucial to controlling aeolian erosion but highly efficient vegetation is critical. How this efficiency is influenced by vegetation response to...
Vegetation cover is crucial to controlling aeolian erosion but highly efficient vegetation is critical. How this efficiency is influenced by vegetation response to airflow is not clear. Here we evaluate the responses of Cosmos bipinnatus and Ligustrum lucidum Ait to a range of wind speeds in a wind tunnel. For both species, we calculate shelter effect and sand flux. We show that plant effectiveness in reducing wind speed and sediment transport is linked to their aerodynamic response to airflow which results from their morphology. We demonstrate that in low-density cover the flow-response and resistance of individuals is most critical in the optimal effectiveness of a canopy. Our wind tunnel experiment suggests that vegetation morphology and structure must be priority parameters in facilitating aeolian erosion control.
Topics: Air Movements; Geologic Sediments; Plants
PubMed: 28993700
DOI: 10.1038/s41598-017-13084-x -
Industrial Health Apr 2001Current fiber measurement techniques arose primarily due to health concerns over asbestos exposure. Fiber toxicity appears to be primarily a function of fiber... (Review)
Review
Current fiber measurement techniques arose primarily due to health concerns over asbestos exposure. Fiber toxicity appears to be primarily a function of fiber concentration, dimensions and durability in the lungs. There are two basic approaches to fiber measurement. Fibers can be collected on filters and counted or analyzed by light or electron microscopy; alternatively, fibers can be detected directly using a combination of fiber alignment and light scattering techniques. All of these measurement approaches work best when the fibers are simple rod-shaped particles. However, most fibers can exist as curved rods, complex bundles of fibrils, and agglomerates of fibers and compact particles. These non-ideal shapes contribute to measurement bias and variability.
Topics: Air; Asbestos; Glass; Humans; Image Processing, Computer-Assisted; Microscopy; Mineral Fibers; Optics and Photonics; Particle Size
PubMed: 11341557
DOI: 10.2486/indhealth.39.39