120 research outputs found

    Review of the background and application of triolein-containing semipermeable membrane devices in aquatic environmental study

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    This paper briefly reviews research on passive in situ samplers for aquatic environments but focuses on the development and application of the triolein-containing semipermeable membrane device in aquatic environmental monitoring. Special attention is paid to the calibration of the devices, quality control issues, and its potential uses in environmental assessments of aquatic contaminants. Also, the suitability of the technique for incorporation with selected bioassays is examined

    Rate effect of liquid infiltration into mesoporous materials

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    Rate effect of liquid infiltration in mesopores is associated with both liquid viscosity and the solid–liquid interfacial effect.</p

    Clinical study on the effect of remifentanil patient-controlled intravenous labor analgesia compared to patient-controlled epidural labor analgesia

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    Objectives: This study aims to investigate the safety and efficacy of remifentanil for patient-controlled intravenous labor analgesia as an alternative to the patient-controlled epidural labor analgesia. Material and methods: Out of 453 parturients who volunteered for labor analgesia and were selected as research objects, 407 completed the trial. They were divided into the research group (n = 148) and the control group (n = 259; patient-controlled epidural analgesia). In the research group, the first dose of remifentanil, the background dose and the patient-controlled analgesia (PCA) dose were 0.4 μg/kg, 0.04 μg/min and 0.4 μg/kg, respectively, with a lockout interval of 3 min. The control group was given epidural analgesia. The first dose and background dose were 6–8 mL, and PCA dose and the locking time of analgesia pump were 5 mL and 20 min, respectively. The following indexes of the two groups were observed and recorded: the analgesic and sedative effects on parturient, labor process, forceps delivery, cesarean section rate and adverse reactions, and maternal and neonatal conditions. Results:1. The onset time of analgesia in the research group was (0.97 ± 0.08) min, which was noticeably shorter than that in the control group ([15.74 ± 1.91] min), with a statistically significant difference (t = –93.979, p = 0.000).2. There was no significant difference in the labor process, forceps delivery, cesarean section rate and neonatal condition between the two groups (p &gt; 0.05). Conclusions: Remifentanil patient-controlled intravenous labor analgesia has the advantage of rapid onset of labor analgesia. Although its analgesic effect is not as accurate and stable as epidural patient-controlled labor analgesia, it shows a high level of maternal and family satisfaction

    The mouse t complex distorter/sterility candidate, Dnahc8, expresses a Îł-type axonemal dynein heavy chain isoform confined to the principal piece of the sperm tail

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    AbstractHeterozygosity for a t haplotype (t) in male mice results in distorted transmission (TRD) of the t-bearing chromosome 17 homolog to their offspring. However, homozygosity for t causes male sterility, thus limiting the spread of t through the population at large. The Ca2+-dependent sperm tail curvature phenotypes, “fishhook”, where abnormally high levels of sperm exhibit sharp bends in the midpiece, and “curlicue”, where motile sperm exhibit a chronic negative curving of the entire tail, have been tightly linked to t-associated male TRD and sterility traits, respectively. Genetic studies have indicated that homozygosity for the t allele of Dnahc8, an axonemal γ-type dynein heavy chain (γDHC) gene, is partially responsible for expression of “curlicue”; however, its involvement in “fishhook”/TRD, if any, is unknown. Here we report that the major isoform of DNAHC8 is copiously expressed, carries an extended N-terminus and full-length C-terminus, and is stable and equally abundant in both testis and sperm from +/+ and t/t animals. By in silico analysis we also demonstrate that at least three of the seventeen DNAHC8t mutations at highly conserved positions in wild-type DHCs may be capable of substantially altering normal DNAHC8 function. Interestingly, DNAHC8 is confined to the principal piece of the sperm tail. The combined results of this study suggest possible mechanisms of DNAHC8t dysfunction and involvement in “curlicue”, and support the hypothesis that “curlicue” is a multigenic phenomenon. They also demonstrate that the accelerated “fishhook” phenotype of sperm from +/t males is not directly linked to DNAHC8t dysfunction

    Circle Line Optimization of Shuttle Bus in Central Business District without Transit Hub

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    The building density of Central Business District (CBD) is usually high. Land for a bus terminal is insufficient. In this situation, passengers in CBD have to walk far to take a bus, or take a long time to wait for a taxi. To solve this problem, this paper proposes an indirect approach: the design of a circle line of shuttle bus as a dynamic bus terminal in CBD. The shuttle bus can deliver people to the bus station through a circle line. This approach not only reduces the traffic pressure in CBD, but also saves travel time of the passenger. A bi-objective model is proposed to design a circle line of a shuttle bus for CBD. The problem is solved by non-dominated sorting genetic algorithm (NSGA-II). Furthermore, the Dalian city in China has been chosen as the case study to test the proposed method. The results indicate that the method is effective for circle line optimization of shuttle bus in central business district without a bus terminal

    Genome-Wide Association Mapping and Genomic Prediction Analyses Reveal the Genetic Architecture of Grain Yield and Flowering Time Under Drought and Heat Stress Conditions in Maize

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    Drought stress (DS) is a major constraint to maize yield production. Heat stress (HS) alone and in combination with DS are likely to become the increasing constraints. Association mapping and genomic prediction (GP) analyses were conducted in a collection of 300 tropical and subtropical maize inbred lines to reveal the genetic architecture of grain yield and flowering time under well-watered (WW), DS, HS, and combined DS and HS conditions. Out of the 381,165 genotyping-by-sequencing SNPs, 1549 SNPs were significantly associated with all the 12 trait-environment combinations, the average PVE (phenotypic variation explained) by these SNPs was 4.33%, and 541 of them had a PVE value greater than 5%. These significant associations were clustered into 446 genomic regions with a window size of 20 Mb per region, and 673 candidate genes containing the significantly associated SNPs were identified. In addition, 33 hotspots were identified for 12 trait-environment combinations and most were located on chromosomes 1 and 8. Compared with single SNP-based association mapping, the haplotype-based associated mapping detected fewer number of significant associations and candidate genes with higher PVE values. All the 688 candidate genes were enriched into 15 gene ontology terms, and 46 candidate genes showed significant differential expression under the WW and DS conditions. Association mapping results identified few overlapped significant markers and candidate genes for the same traits evaluated under different managements, indicating the genetic divergence between the individual stress tolerance and the combined drought and HS tolerance. The GP accuracies obtained from the marker-trait associated SNPs were relatively higher than those obtained from the genome-wide SNPs for most of the target traits. The genetic architecture information of the grain yield and flowering time revealed in this study, and the genomic regions identified for the different trait-environment combinations are useful in accelerating the efforts on rapid development of the stress-tolerant maize germplasm through marker-assisted selection and/or genomic selection

    Determination of 4 Kinds of β-Agonists Residues in Braised Meat by Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry

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    An ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS) method was developed for the determination of four β-agonists (terbutaline, clenbuterol, ractopamine, salbutamol) in braised meat. Samples were hydrolyzed by β-glucuronidase and cleaned up by an SLS solid phase extraction column. The separation was performed on a Thermo Hypersil Gold C18 column with a gradient elution of 0.1% formic acid water and acetonitrile as mobile phases, ESI+ was used for multiple response monitoring (MRM) and quantitative analysis by internal standard method. The linear relationship of the four β-agonists was good in the concentration range of 0.5 μg/L to 9.5 μg/L, and the correlation coefficient (r) was greater than 0.9988. The limit of detection (LOD) was 0.1 μg/kg, and the limit of quantitation (LOQ) was 0.3 μg/kg. The recoveries were 87.9%~113.7% and RSDs were 1.48%~9.32% at three spiked levels (1, 5 and 9 μg/kg). In a total of 162 batches of braised meat samples, one sample of braised pig’s trotter was found to contain 1.51 μg/kg of clenbuterol and 3.65 μg/kg of ractopamine. Additionally, another sample of braised lamb was found to contain 11.5 μg/kg of clenbuterol. The method is rapid and accurate, and can be used for qualitative and quantitative determination of four β-agonists (terbutaline, clenbuterol, ractopamine, salbutamol) in braised meat
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