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With the goal of enhancing the low sensitivity of the conventional atmospheric pressure chemical ionization (APCI) source due to the ion divergence, here is reported a T-shaped ion source to improve the sensitivity with a portable mass spectrometer for the rapid determination of the pesticides ethoprophos and atrazine in water. Compared with conventional APCI, the ion source improves the sensitivity for the analytes. The results show that the analysis requires less than 2 s, the limit of detection (LOD) is better than 0.1 μ g · mL − 1 , and the relative standard deviation (RSD) is 16% at 1, 5, and 25 μ g · mL − 1 . The recoveries of the analytes are between 80% and 130%, meeting the requirements for rapid pesticide determination in water. [ABSTRACT FROM AUTHOR]

With the increasing prevalence of illicit drugs, social security and human health are at serious risk. However, traditional detection techniques require a lengthy pretreatment process to eliminate matrix interference and do not allow rapid, in situ analysis. Ambient ionization is a powerful tool for the rapid determination of illicit drugs in different matrices because it usually eliminates the need for sample pretreatment, and the portable mass spectrometer brings convenience to in situ detection. This study employed a thermal desorption-electrospray ionization (TD-ESI) source combined with a portable mass spectrometer to rapidly characterize illicit drugs in drinks, instant powders, and solid food surfaces. Air was utilized instead of nitrogen as the carrier gas for TD-ESI/MS in order to save space and cost together with rapid on-site analysis. A full-scan waveform combined with a qualitative pre-scan waveform (QPSW) was employed to form a two-step scanning mode to accurately identify the drugs. The results showed that the limits of detection (LODs) for the analytes were 100–200 ppb in drinks, 700–1000 ppb in instant powders, and 1 ng/cm2 on solid food surfaces. The complete TD-ESI/MS analysis time was less than 1 min. [ABSTRACT FROM AUTHOR]

While portability is a key aspect of small mass spectrometers, they also need to be able to effectively screen the analytes from complex matrices. The accuracy and performance of mass spectrometers depend not only on the identification of parent ion signals in targets but also fragment ion signals. This paper reports on the construction of a device that uses a new time-domain excitation waveform called qualitative pre-scan waveform (QPSW) for its quadrupole ion trap mass spectrometry analyzer. This approach uses scanning to eliminate interfering ions, thus improving the sensitivity for the analyte and removing the cumbersome steps required to convert conventional stored waveform inverse Fourier transform (SWIFT) waveforms from the frequency domain to the time domain. Tests show that the target ions can be fragmented just by introducing air at the moment when the pinch valve is opened without any need for a carrier gas. This simplifies the equipment required, making the mass spectrometer more portable. Tests were undertaken to compare the performance with the use of conventional SWIFT waveforms and to optimize its experimental parameters so that the target ions were effectively accumulated in the ion trap. An approximate 5-fold improvement in sensitivity was achieved by QPSW compared to the SWIFT for 2 μg/mL ketamine. A 5-fold reduction in the limit of detection (LOD) to 20 ng/mL was also obtained for enrofloxacin. In addition, the stability was improved by QPSW with a relative standard deviation less than 13% compared to 16% for SWIFT. [ABSTRACT FROM AUTHOR]

Reducing wear and stabilizing the coefficient of friction (COF) are always frontier issues in the field of automobile braking materials. In this study, the wear resistance of carbon materials and the friction stability of porous materials were combined. Rice husk carbon (RHC) was prepared via vacuum pyrolysis, and the effects and mechanism of RHC contents on the tribological properties of non-asbestos organic braking composite materials (NAOBCM) were studied. The RHC was a porous carbon material mainly containing amorphous carbon and silicon dioxide (SiO2). The COF was improved and stabilized, and the wear resistance was significantly enhanced by adding low-dose RHC. The optimal performance was achieved at 4wt% RHC. As for the mechanism, the porous structure of RHC can prevent stress expansion on the worn subsurface, thus alleviating delamination wear and decreasing the number of large-size abrasive debris. As a result, the abrasive wear is relieved. Finally, the smaller peel-off pits and ploughs reduces roughness and improves the performance. [ABSTRACT FROM AUTHOR]

This study aimed to assess the effects of Apolipoprotein E (APOE) gene polymorphisms, dietary nutrient intake, and their interactions on the prevalence of dyslipidemia in a Yao minority area, China. rs429358, rs7412, rs7259620, and rs405509 of the APOE gene were genotyped in 1014 adults aged ≥30 years by using the MassArray system. Dietary nutrients intake data were ascertained from a 109-item food frequency questionnaire (FFQ). Multifactorial logistics regression analysis showed that dyslipidemia was associated with rs7412-CT/TT genotype (OR: 0.540, Bonferroni correction confidence interval: 0.336–0.869), high fat intake (OR: 1.644, 95% CI: 1.128–2.395), high saturated fatty acid (SFA) intake (OR: 1.668, 95% CI: 1.146–2.428), medium carbohydrate intake (OR: 0.634, 95% CI: 0.461–0.873) and high carbohydrate intake (OR: 0.591, 95% CI: 0.406–0.858). The results of logistics regression multiplication model showed that medium carbohydrate intake in the carriers of the rs7412 minor alleles was associated with a low risk of dyslipidemia (OR: 0.433, Bonferroni correction confidence interval: 0.199–0.941). Genetic variations at the rs7412, dietary fat, SFA, and carbohydrate intake and the interaction between APOE gene polymorphisms and carbohydrate intake are associated with dyslipidemia in Yao nationality people. [ABSTRACT FROM AUTHOR]

We consider price and inventory decisions in a make-to-stock system from the perspectives of a profit-maximizing server and a social planner in which customers are delay-sensitive. Under two information cases (i.e. an almost unobservable case and a fully observable case), customers decide whether to purchase the product based on their utility. The utility is closely related to whether the inventory of the product is available, the product's price, and the waiting time. We first investigate the optimal decision in the almost unobservable case. In this case, the server's inventory strategy depends on the relationship between the unit holding cost of the product and the unit waiting cost of the customer. Additionally, the system utilization factor also affects the inventory strategy. Then, we analyse the corresponding results in the fully observable case. The results illustrate that, in both cases, profit maximization and welfare maximization lead to different pricing and inventory strategies. Finally, the numerical results show that the optimal price is sensitive to delay information, whereas the optimal stock level is not. [ABSTRACT FROM AUTHOR]

Natural environment is an important factor affecting longevity. Soil, water and hair samples from Bama were assayed to investigate the effects of elements on the regional longevity. The concentrations of Cd, Co and Mg in soil and Co in drinking water were significantly higher in longevity area than those in non-longevity area (p < 0.05). The concentrations of K, Mo, Na, Pb and V in soil, Mg, Na, Fe, Li and Mn in drinking water and I, K, Mg, Mn, Na and Sr in hair were significantly lower in longevity area than those in non-longevity area (p < 0.05). Mg, Mn, Na and Sr in hair were affected by soil and drinking water. Our results indicate that adequate concentration of Mg in soil might benefit longevity, excessive concentrations of Na in soil, Mg, Mn and Na in drinking water and Mg, Mn, Na and Sr in hair might reduce lifespan of local residents. [ABSTRACT FROM AUTHOR]

A rare sinulariane-type norcembranoid sinulariadiolide B (1) with a unique cyano group, and a eunicellin-based diterpenoid multifloralin (2), along with two known related analogues, sinulariadiolide (3) and sclerophytin E (4), were isolated from the extract of the South China Sea soft coral Sinularia multiflora. Their structures were elucidated on the basis of detailed spectroscopic analysis and by comparison with previously reported data. Compounds 2 and 4 showed potent antifouling activity against barnacle Balanus albicostatus. [ABSTRACT FROM AUTHOR]

AbstractAdolescents’ bystander defending behavior in cyberbullying contributes to reducing the harm done to cyberbullying victims. This study examined the relationships and underlying mechanisms of parental warmth, friendship quality, empathy and bystander defending behavior in cyberbullying among 848 Chinese adolescents (43.986% girls, mean age = 14.960 years old [SD = 1.398]). The results showed that parental warmth, friendship quality and empathy were all positively correlated with bystander defending behavior in cyberbullying among adolescents. Both friendship quality and empathy played a mediating role between parental warmth and bystander defending behavior in cyberbullying, indicating that parental warmth was associated with increased bystander defending behavior through higher levels of friendship quality and empathy, respectively. Friendship quality and empathy also played a chain mediating role between these two, indicating that parental warmth was linked to increased bystander defending behavior by first associating with higher level of friendship quality and subsequently with greater empathy. These results suggest that high degrees of parental warmth, friendship quality and empathy may all increase the likelihood of bystander defending behavior in cyberbullying among adolescents. This study provides practical implications for improving adolescent bystander defending behavior in cyberbullying. [ABSTRACT FROM AUTHOR]