Search

Background Pydiflumetofen, as a new succinate dehydrogenase inhibitor (SDHI) chiral fungicide, has been used in crop production because of its broad-spectrum and high-efficiency antifungal activity. However, little literature is known about pydiflumetofen at the chiral level. Therefore, the stereoselective bioactivity and degradation of pydiflumetofen enantiomers were investigated. Results Pydiflumetofen presented effective bioactivity against the eight tested phytopathogens, and its enantiomers showed significant difference in activity. The bioactivity of R-pydiflumetofen was 9.0 ~ 958.8 times higher than that of S-enantiomer. Treatment with R-pydiflumetofen increased the cell membrane permeability of Sclerotinia sclerotiorum and decreased more exopolysaccharide and oxalic acid production more than treatment with S-pydiflumetofen. Furthermore, R-pydflumetofen exhibited better inhibitory activity against the succinate dehydrogenase (SDH) enzyme of S. sclerotiorum than S-pydiflumetofen by 584-folds. According to homology modeling and molecular docking studies, the binding affinities of the R-enantiomer and S-enantiomer were - 7.0 kcal mol-1 and -5.3 kcal mol-1 , respectively. Additionally, the degradation half-lives of S- and R-pydiflumetofen in three vegetables (cucumber, eggplant, and cowpea) under field conditions were 2.56 ~ 3.12 d and 2.48 ~ 2.76 d, respectively, which revealed that R-pydiflumetofen degraded faster than S-pydiflumetofen. Conclusion Based on the results obtained, R-pydiflumetofen not only exhibited a higher bactericidal activity, but also posed fewer residual risks in the environment. The mechanism of the stereoselective bioactivity was correlated with the stereoselective inhibition activity of the target enzyme and then effected the cell membrane permeability and the production of exopolysaccharide and oxalic acid. This research could provide a foundation for the systematic evaluation of pydiflumetofen from an enantiomeric view. This article is protected by copyright. All rights reserved.

As a forceful nematicide, fosthiazate has been largely applied in the management of root-knot nematodes and other herbivorous nematodes. However, the toxicity of fosthiazate to nontarget nematodes is unclear. To explore the toxicity and the mechanisms of fosthiazate in nontarget nematodes, Caenorhabditis elegans was exposed to 0.01-10 mg/L fosthiazate. The results implied that treatment with fosthiazate at doses above 0.01 mg/L could cause injury to the growth, locomotion behavior, and reproduction of the nematodes. Moreover, L1 larvae were more vulnerable to fosthiazate exposure than L4 larvae. Reactive oxygen species (ROS) production and lipofuscin accumulation were fairly increased in 1 mg/L fosthiazate-exposed nematodes. Treatment with 0.1 mg/L fosthiazate significantly inhibited the activity of acetylcholinesterase (p0.01). Furthermore, subacute exposure to 10 mg/L fosthiazate strongly influenced the expression of genes related to oxidative stress, reproduction, and nerve function (e.g., gst-1, sod-1, puf-8, wee-1.3, and ace-1 genes). These findings suggested that oxidative stress, reproduction and nerve disorders could serve as key endpoints of toxicity induced by fosthiazate. The cyp-35a family gene was the main metabolic fosthiazate in C. elegans, and the cyp-35a5 subtype was the most sensitive, with a change in expression level of 2.11-fold compared with the control. These results indicate that oxidative stress and neurological and reproductive disorders played fundamental roles in the toxicity of fosthiazate in C. elegans and may affect the abundance and function of soil nematodes.

Cyproconazole (CPZ), representing the chiral triazole fungicides, is widely used in the pharmaceutical and agricultural fields. To clarify its potential adverse effects on the generalized CYP-mediated processes within mammalian, a comparative experimental and computational approach was employed to investigate the CYP-mediated metabolism processes of CPZ stereoisomers in rat liver microsomes (RLMs). The depletion rate of CPZ stereoisomers in vitro incubation system with RLMs followed the order RR-> SS-> SR-> RS-CPZ. The results of kinetic assays were in line with the depletion rate results. Further inhibition assay confirmed the stereo selective metabolism of CPZ stereoisomers by different CYP isoforms. Molecular dynamics (MD) simulation revealed the stereoselective metabolism mechanism. Several hydrogen bonds and pi-stacking restrict the position of CPZ isomers in the active cavity of CYPs so that the 4'-nitrogen on the triazole ring can bind closely to the heme of CYP, which results in the metabolism of CPZ isomers. By combining the computational and experimental approaches, the structure-activity relationship of CPZ and CYP was elucidated, and this method can be further applied to predict the degree of uncertainty in the process of xenobiotic biotransformation of triazole fungicides and serve as a basis for risk assessment.

Pydiflumetofen is a novel and efficient broad-spectrum chiral fungicide consisting of a pair of enantiomers. A simple and sensitive chiral analytical method was established to determine the enantiomers of this chiral fungicide in food and environmental samples by ultra-high-performance liquid chromatography tandem triple quadrupole mass spectrometry (UHPLC-MS/MS) using QuEChERS method coupled with octadecylsilane-dispersive solid-phase extraction (C18-dSPE) as extraction procedure. The specific optical rotation and the absolute configuration of the enantiomers were identified by polarimetry and electronic circular dichroism (ECD). The elution order of the pydiflumetofen enantiomers on Lux Cellulose-2 was S-(−)-pydiflumetofen and R-(+)-pydiflumetofen. The average recoveries of eleven matrices ranged from 71.3% to 107.4%. The intraday relative standard deviations (RSDs) were less than 11.8%, and the interday RSDs were less than 12.6% for the two enantiomers. Stereoselective dissipation in pakchoi and soil were observed: S-(−)-pydiflumetofen was degraded faster than R-(+)-pydiflumetofen in pakchoi, causing the enantiomer fraction (EF) of the enantiomers to change from 0.50 to 0.42 in 7 days. However, R-(+)-pydiflumetofen was degraded faster than S-(−)-pydiflumetofen in soil, causing the EF of the enantiomers to change from 0.49 to 0.52 in 21 days. This study provides a method for monitoring pydiflumetofen enantiomer residues, which is crucial for improving risk assessments and the development of chiral pesticides.

To conduct genetic diagnosis for a family affected with hamophilia A.Potential mutations of the F8 gene were analyzed with PCR and Sanger sequencing. Carriers of the mutation were identified through linkage analysis using short tandem repeat (STR) markers. Suspected mutations were verified among 100 healthy controls to rule out genetic polymorphism. Prenatal diagnosis was provided based on the above results.Sequencing analysis has identified two mutations, c.1 AT and c.4 CT, which have replaced the start codon (ATG) with leucine (TTG) and glutamine (GAA) with the stop codon (TAA), respectively. The same mutations were not found among the 100 healthy controls. The patient's mother and sister were heterozygous for the same mutations. Upon prenatal diagnosis, the fetus was determined as a male and did not harbor the above mutations. Linkage analysis also confirmed that the fetus has inherited the non-risk X chromosome from his maternal grandfather.Detection of pathogenic mutations can enable prenatal diagnosis for the disease.

To use combined G-banding and array-comparative genomic hybridization (aCGH) for the prenatal diagnosis of a fetus with 5q35 deletion syndrome.Chromosomal karotypes of the fetus and parents were analyzed with G-banding analysis. aCGH was performed to detect minor chromosomal structural abnormalities.The karyotype of the fetus was ascertained as 46, XY, t(5;10)(q35;p13), and the karyotypes of the parents were normal. aCGH has identified a de novo 1.68 Mb deletion at 5q35.2q35.3 and a 1.44 Mb duplication at 10p14p13.aCGH has a higher resolution and greater accuracy for mapping chromosomal aberrations and is a useful supplement for G banding karyptyping analysis.

Background Alcohol contributes to approximately 30% of all serious crashes. While the majority of drivers acknowledge the risks associated with drink-driving, a significant proportion of the population continue to engage in this behaviour. Attitudes towards drink-driving as well as personal alcohol consumption patterns are likely to underpin a driver’s decision to drink-drive. These associations were explored in the current study. Methods A large (N = 2994) cross-sectional online survey of a representative sample of drivers in Australia was conducted. Participants provided information about their own alcohol consumption patterns, drink-driving behaviour as well as attitudes towards drink-driving (own and others) and enforcement strategies. Results Alcohol consumption patterns differed according to age, gender and work status. Drivers who reported drink-driving behaviour and had high risk alcohol consumption patterns were less likely to agree that drink-driving leads to increased crash risk and more likely to agree they drink and drive when they believed they could get away with it. In contrast, drivers who did not report drink-driving and had low risk consumption patterns were more likely to report that the enforcement strategies are too lenient. Binary logistic regression showed that high risk alcohol consumption patterns and agreement from drivers that they drink and drive when they believe they can get away with it had the strongest associations with drink-driving. These findings highlight the relationships between one’s drinking patterns, drink-drive behaviour and attitudes towards drink-driving and drink-driving enforcement Conclusions and implications The patterns of associations that emerged suggest that drink-driving is the expression of a broader health issue for the most “at-risk” cohort of drinkers. The decision to drink and drive may result from a need borne from an alcohol dependent lifestyle exacerbated by a social acceptability of the behaviour and positive attitudes towards one’s ability to drink-drive with few adverse consequences. Therefore, the broader alcohol consumption patterns of drink-drivers needs to be considered when targeting drink-drive reductions.

In the current study, we conducted daily telephone interviews with a sample of Chinese workers (N = 57) for 5 weeks to examine relationships between daily work-family conflict and alcohol use. Drawn from the tension reduction theory and the stressor-vulnerability model, daily work-family conflict variables were hypothesized to predict employees' daily alcohol use. Further, social variables (i.e., peer drinking norms, family support, and coworker support) were hypothesized to moderate the relationship between work-family conflict and alcohol use. Results showed that daily work-to-family conflict but not family-to-work conflict had a significant within-subject main effect on daily alcohol use. In addition, there was significant between-subject variation in the relationship between work-to-family conflict and alcohol use, which was predicted by peer drinking norms, coworker support, and family support. The current findings shed light on the daily health behavior consequences of work-family conflict and provide important theoretical and practical implications.

Square pool fires with length of 5, 7.5, 10, 15, 20, 25 and 30 cm and rectangular pool fires with dimensions of 10 cm × 20 cm and 10 cm × 40 cm were burned in a wind tunnel, under a longitudinal air flow ranged from 0 to 3 m/s with incremental change of about 0.5 m/s. Methanol and gasoline were burned and compared, with results indicated that their burning rates showed different response to the longitudinal air flow. With the increase of the longitudinal air flow speed, the burning rates of methanol pool fires, except the 5 cm square one, first decreased and then increased, but those of the 5 cm methanol square one and the gasoline pool fires increased monotonously. The burning rate of smaller square pool fires increased more significantly than that of the larger ones, as well as the enlargement of their flame attachment length along the ground. The burning rate of a rectangular pool fire with longer rim parallel to the longitudinal flow increased faster, but the flame attachment length seemed to increase more gradually, with the increase of the longitudinal air flow speed than that perpendicular to.

Objective To study the epidemiologic characteristics of burns in the elderly patients to reduce risks. Methods Features, including causes, seasonality, co-morbidities and mortality among 280 burned patients over 60 years old, admitted to Burn Unit, Southwest Hospital from 1999 to 2006, were analyzed retrospectively. Results The incidence of burns in the elderly has been decreasing gradually from 4.35% in 1999 to 3.81% in 2006. The geriatric burns could happen any time during a year, but most frequently in summer and winter. Seventy percent of the geriatric burns were related to activities of daily life. The co-morbid conditions in the elderly, which comprised 83.9% of the victims, contributed to the burn outcomes. No difference in morbidity was found between rural and urban patients. However, mortality was significantly higher in the rural patients with 30% over TBSA burns. Conclusion The incidence of geriatric burns has been decreasing associated with social and individual living levels in China. However, the disparity in the mortality rates between rural and urban suggests investment in rural China is needed to reduce health inequalities.

A model based on the perfectly stirred reactor (PSR) concept is developed and utilized in the prediction of the minimum extinguishing concentration (MEC) of inert fire suppression agents established in the standard cup-burner test. Both physical and chemical mechanisms of fire suppression are considered in PSR modeling. Transport mechanisms are not modeled. Results are contrasted to experimental data and to a semi-analytical approach that assumes heat absorption by the agent is the primary extinguishing mechanism. Good agreement is achieved validating both the PSR approach and the conclusion that agent heat capacity has the first-order effect in the determination of the MEC. PSR results further capture a second-order chemical effect of oxygen depletion on the MEC. The PSR model is also used in a parametric assessment of the impact of test conditions on the MEC. Results show that cooling of the agent or heating of the fuel have a minor effect on the MEC. Variations on atmosphere conditions, such as temperature, pressure and humidity, have a more pronounced effect on the MEC. These results are interpreted in terms of the changing heat capacity of the inerting atmosphere and the altered chemical reactivity of the combustible mixture.

An analytical model was developed to investigate the dynamics of nonpremixed flames in a shear layer established between a mainstream flow of fuel-rich combustion products and a porous surface with an angled injection of air. In the model, a one-step overall chemical reaction was employed, together with boundary layer conservation equations solved using similarity solutions. Parametric studies were performed to understand the effects of equivalence ratio, temperature, and mass flow rate of the fuel and air streams on the flame standoff distance, surface temperature, and heat flux at the surface. The analytical model predictions were compared with computational fluid dynamics results obtained using the FLUENT commercial code for both the laminar and the turbulent flow models. Qualitative agreement in surface temperature was observed. Finally, the flame stability limits predicted by the model were compared with available experimental data and found to agree qualitatively, as well.

The traditional methods to solve the PV mismatch problem are using diodes and photovoltaic cells in series and in parallel to compensate voltage and current. Considering the cost of production, it is unrealistic that each photovoltaic cell parallels with one bypass diode. One bypass diode may parallels with dozen or more solar cells. Therefore, the connection of the photovoltaic cells in parallel with bypass diodes is very important. This paper proposes the traditional connection may reduce the whole PV modules output power when the shadow covers partial modules. A new photovoltaic cells connection, named "door-connection", is proposed to solve this problem. The paper analyses the characteristics of the door-connection output power in three typical shadow cases. It is proved that the new connection can improve the output power obviously compared with the traditional connection.

The effect of unsteady strain on n-heptane autoignition at elevated pressure is studied numerically with detailed chemistry and transport in the counterflow configuration. Specifically, fuel and air temperatures are chosen so that two-stage ignition occurs, as is typical, in the negative temperature-coefficient regime, and the strain perturbations are selected to rapidly rise and fall to mimic rapid turbulent strain-rate fluctuations. For these rapid fluctuations, the response of the mixing layer is unsteady. Small to moderate strain-rate fluctuations result in a small increase in the ignition delay. For sufficiently large strain rates such that the critical scalar dissipation rate is exceeded, the ignition delay is substantially greater. The latter delay results from both the time required for the dissipation rate to decay to below its critical value and the longer ignition delay time for systems with dissipation rates near the critical dissipation rate. For all magnitudes of strain-rate fluctuation, there is evidence that the second stage of the two-stage ignition is more sensitive to inhibition by higher dissipation rates. For sufficiently large dissipation rates, the heat losses force the second stage to the border between the low- and intermediate-temperature chemistries.

This paper presents an improved Particle Swarm Optimization algorithm (IPSO) for solving the flexible load dispatch problem (FLD) which relates to renewable energy power generation and three types of load composed of electric vehicle (EV), ice-storage central air conditioning and smart household appliance. The objective of the FLD problem is to utilize aggregators of the three types of load to deal with the unpredictability and intermittence of the renewable energy power generation. Facing premature convergence of PSO, the proposed method divides the search process into two stages. In the first stage, every particle selects one particle randomly to learn. The second stage is the conventional PSO algorithm. The total length the optimal particle flights for, the average velocity and the distance of every iteration are used to evaluate performance of PSO and IPSO. The results of a 12-unit system show that the IPSO is more stable and effective than PSO.

The effect of steady strain on the transient autoignition of n-heptane at high pressures is studied numerically with detailed chemistry and transport in a counterflow configuration. Skeletal and reduced n-heptane mechanisms are developed and validated against experiments over a range of pressure and stoichiometries. Two configurations are investigated using the skeletal mechanism. First, the effect of strain rate on multistage n-heptane ignition is studied by imposing a uniform temperature for both the fuel and the oxidizer streams. Second, a temperature gradient between the fuel and the oxidizer streams is imposed. The global effect of strain on ignition is captured by a Damkohler number based on either the heat-release rate or the characteristic chain-branching rate. Results show that for low to moderate strain rates, both the low- and intermediate-temperature chemistries evolve in a manner comparable to that in homogeneous systems, including the negative temperature coefficient regime, but with somewhat slower evolution attributable to diffusive losses. At high strain rates diffusive losses inhibit ignition; for two-stage ignition, it is found that ignition is inhibited during the second, intermediate-temperature stage. The imposition of an overall temperature gradient further inhibits ignition because reaction zones for key branching reactions with large activation energies are narrowed. For a fixed oxidizer stream temperature that is not sufficiently high, a higher fuel temperature results in a shorter ignition delay provided that the heptyl radicals are mainly oxidized by low-temperature chemistry. As expected, an increase in pressure significantly increases reaction rates and reduces ignition delay time. However, with increasing pressure there is a shift toward single-stage low-temperature-dominated ignition which serves to delay ignition.

Ceramic Matrix Composite (CMC) combustor liners, due to their high temperature capability, enable the elimination of film cooling present in current metallic liners without increasing the pressure drop in the combustor section of a gas turbine engine. The absence of film cooling and the higher temperature capability of the CMC liner leads to complete combustion of carbon monoxide (CO) close to the combustor walls, resulting in a lower emissions combustor. The benefit of lower CO emissions was predicted through the use of stirred reactor network models in which a series/parallel set of individual perfectly stirred reactors (PSRs) is coupled to simulate a combustor. The paper describes the component design and analysis, emissions modeling, fabrication, and sector rig testing of silicon carbide fiber reinforced silicon carbide matrix (SiC/SiC) combustor liners.Copyright © 2006 by ASME

Power sources capable of supplying tens of watts are needed for a wide variety of applications including portable electronics, sensors, micro aerial vehicles, and mini-robotics systems. The utility of these devices is often limited by the energy and power density capabilities of batteries. A small combustion engine using liquid hydrocarbon fuel could potentially increase both power and energy density by an order of magnitude or more. This report describes initial development work on a meso-scale external combustion engine based on the Stirling cycle. Although other engine designs perform better at macro-scales, we believe the Stirling engine cycle is better suited to small-scale applications. The ideal Stirling cycle requires efficient heat transfer. Consequently, unlike other thermodynamic cycles, the high heat transfer rates that are inherent with miniature devices are an advantage for the Stirling cycle. Furthermore, since the Stirling engine uses external combustion, the combustor and engine can be scaled and optimized semi-independently. Continuous combustion minimizes issues with flame initiation and propagation. It also allows consideration of a variety of techniques to promote combustion that would be difficult in a miniature internal combustion engine. The project included design and fabrication of both the engine and the combustor. Two engine designs were developed. The first used a cylindrical piston design fabricated with conventional machining processes. The second design, based on the Wankel rotor geometry, was fabricated by through-mold electroforming of nickel in SU8 and LIGA micromolds. These technologies provided the requisite precision and tight tolerances needed for efficient micro-engine operation. Electroformed nickel is ideal for micro-engine applications because of its high strength and ductility. A rotary geometry was chosen because its planar geometry was more compatible with the fabrication process. SU8 lithography provided rapid prototypes to verify the design. A final high precision engine was created via LIGA. The micro-combustor was based on an excess enthalpy concept. Development of a micro-combustor included both modeling and experiments. We developed a suite of simulation tools both in support of the design of the prototype combustors, and to investigate more fundamental aspects of combustion at small scales. Issues of heat management and integration with the micro-scale Stirling engine were pursued using CFD simulations. We found that by choice of the operating conditions and channel dimensions energy conversion occurs by catalysis-dominated or catalysis-then-homogeneous phase combustion. The purpose of the experimental effort in micro-combustion was to study the feasibility and explore the design parameters of excess enthalpy combustors. The efforts were guided by the necessity for a practical device that could be implemented in a miniature power generator, or as a stand-alone device used for heat generation. Several devices were fabricated and successfully tested using methane as the fuel.

Tornado preparedness warning system effectiveness, and shelter-seeking behavior were examined in two Alabama areas after tornado warnings. In the area without sirens, only 28.9% of 194 respondents heard a tornado warning of these, 73.2% first received the warning from radios or television. In the area with sirens, 88.1% of 193 respondents heard a warning, and 61.8% first received the warning from a siren. Knowledge of warnings, access to shelter, and education were key predictors for seeking shelter. Our findings indicate that installing sirens, providing access to shelter, and teaching appropriate responses to warnings are important elements of an effective disaster prevention system.