Esters of 2-monochloropropane-1,2-diol (2-MCPD), 3- monochloropropane-1,2-diol (3-MCPD), and glycidol are present in infant formulas, follow-on foods and similar compositions. They arise mainly from ...the vegetable oil content and may cause harmful effects in consumers. The contents of these substances in formulas were determined indirectly by converting the esters to the free form, followed by derivatization and analysis by gas chromatography-tandem mass spectrometry (GC-MS/MS). The validation results demonstrate that the method had sufficient specificity and adequate accuracy. The limits of detection (LOD) and limits of quantification (LOQ) for each of 2MCPDE, 3MCPDE, and GE were 1.5 and 5 µg/kg, respectively. Formula intake by children up to 36 months of age was surveyed, and the data was used to assess the risks due to 3-MCPD esters (3-MCPDE) and glycidyl esters (GE). The mean exposure dose of 3-MCPDE for different age groups ranged from 0.51 to 1.13 µg/kg bw per day. The corresponding mean GE exposure ranged from 0.031 to 0.069 µg/kg bw per day. Neither mean values nor the percentile 95% values of 3-MCPDE exposure doses exceed the recommended provisional maximum tolerable daily intake (PMTDI).
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Phosphodiesterase type 5 inhibitors (PDE-5i) are the first-line medication for oral erectile dysfunction, which are used according to the prescription of doctors. However, these substances have been ...found illegally in supplementary foods. The quality and safety of dietary supplements for enhancing male sexual performance have been questioned, raising the need for continual development of analytical methods. Liquid chromatography coupled with high-resolution mass spectrometry has become one of the most effective methods to identify and measure PDE-5i concentration. In this research, we focused on (i) developing and validating an effective screening and quantitation method for more than 53 PDE-5i in ingredients and supplementary products using LC-Q-Exactive after a simple sample extraction and (ii) assessing PDE-5i content in natural-based supplementary products available in Vietnam market. The extraction method used a small amount of organic solvent, which makes it more environmentally friendly (greener). The developed method has a limit of detection of 0.4 mg/kg, a limit of quantitation of 1.2 mg/kg, recoveries from 80 to 110%, and repeatability lower than 15%. Ninety-two herbal supplementary foods and ingredients used for enhancement of male sexual performance available in Vietnamese markets were collected. Fourteen PDE-5i including conventional and novel analogous were detected and measured in eighteen food supplements and two formulation ingredient samples.
Information about the occurrence of polybrominated diphenyl ethers (PBDEs) in indoor dusts from various industrial sectors in Southeast Asia is still scarce. In this study, concentrations and ...congener-specific profiles of PBDEs were determined in indoor dusts from industrial factories, offices, and houses in northern Vietnam. Levels of Σ8PBDEs were higher in the office dusts (median 270; range 230–300 ng/g) and factory dusts (170; 89–510 ng/g) than in the house dusts (61; 25–140 ng/g). BDE-209 was the most dominant congener, accounting for 27–98% (average 62%) of Σ8PBDEs, suggesting the abundance of products treated with deca-BDE mixtures. Residential, commercial, and industrial activities in the studied locations of this survey were not significant sources of PBDEs as compared to those of informal waste processing activities in Vietnam. Relatively low PBDE concentrations detected in our dust samples partially reflect effectiveness of the global PBDE phase-out. Human exposure and health risk associated with dust-bound PBDEs were estimated, indicating acceptable levels of risk (i.e., neurobehavioral effects). The contributions of workplace dusts in total daily intake doses of PBDEs via dust ingestion were more important for local workers in informal recycling areas than factory workers and general population, raising the need of appropriate labor protection measures.
Two new triterpenoids, entanolide (1) and methyl 3,4-secotirucalla-23-oxo-4(28),7,24-trien-21-al-3-oate (2), together with nine known compounds (3-11), were isolated from the bark of Entandrophragma ...angolense. Their structures were elucidated based on spectroscopic analyses, mainly 1 D and 2 D NMR spectral data. Compounds 1-6 and 8 were evaluated for their cytotoxicity against HepG2 cells, and compounds 2-5 exhibited weak activities.
Renewable-energy-based generating systems like photovoltaic (PV) systems, and energy storage devices like batteries are mostly considered as two types of main generation sources for the islanded ...operation mode of a low-voltage DC microgrid (LV-DC MG). Dynamic characteristics of the off-grid LV-DC MG, for instance, fluctuation in load power or frequent changes in the PV-system output power; as well as transient characteristics such as DC faults, and switching actions of power devices may reduce the converters’ reliability. To explicate the viewpoints mentioned, this paper will evaluate the reliability of DC-DC step-up converters used for renewable energy-based generation systems, typically for the PV systems of the LV-DC MG from different dynamic and fault conditions. To perform the reliability analysis, the dynamic-voltage-dependent (DVD) failure rate (FR) and fault-current-dependent (FCD) failure rate of the PV-system step-up converter will be formularized. More clearly, the assessment of step-up converter reliability and its discrete components is based on a new combination of the used-time-dependent (UTD) failure rate, FCD-FR, and DVD-FR and the use of a Markov-state transition diagram. Experimental results illustrate that the output capacitor of the boost converter is greatly influenced by the transient and dynamic characteristics of the PV-generating system. The DVD-FR of the boost converter is quite small when compared to its FCD-FR. Moreover, the PV-system boost converter’s reliability is most rapidly decreased by multiple repeated dynamic cases when the LV-DC MG is in the islanded mode. In addition, when considering both dynamic and transient characteristics of the LV-DC MG, two indices, namely, mean-time-to-failure (MTTF), and mean-time-between-failures (MTBF) of the PV-system boost converter could also be quickly reduced.
Time-series and machine-learning methods are being strongly exploited to improve the accuracy of short-term load forecasting (STLF) results. In developing countries, power consumption behaviors could ...be suddenly changed by different customers, e.g. industrial customers, residential customers, so the load-demand dataset is often unstable. Therefore, reliability assessment of the load-demand dataset is obviously necessary for STLF models. Hence, this paper proposes a novel and unified statistical data-filtering method with the best confidence interval to eliminate unexpected noises/outliers of the input dataset before performing various short-term load forecasting models. This proposed novel data-filtering method, so-called the data pre-processing method, is also compared to other existing data-filtering methods (e.g. Kalman filter, Density-Based Spatial Clustering of Applications with Noise, Wavelet transform, and Singular Spectrum Analysis). By using an SCADA system-based database of a typical 22kV distribution network in Vietnam, NYISO database, and PJM-RTO database, case studies of short-term load forecasting have been conducted with a conventional ARIMA model, an ANN forecasting model, an LSTM-RNN model, an LSTM-CNN combined model, a deep auto-encoder (DAE) network, a Wavenet-based model, a Wavenet and LSTM hybrid model, and a Wavelet Neural Network (WNN) model, which are to validate the novel and unified statistical data-filtering method proposed. The achieved numerical results demonstrate which the accuracy of the aforementioned STLF models can be significantly improved due to the proposed statistical data-filtering method with the best confidence interval of the input load dataset. The proposed statistical data-filtering method can considerably outperform the existing data-filtering methods.
The bidirectional power-converter (BPC) reliability of battery energy storage systems (BATT-ESSs) in a local off-grid energy community (LOEC) is susceptible to dynamic and fault scenarios. As a great ...advantage of the BPC, it is widely used for balancing the power between all generating sources and all required loads in the DC microgrid (MG). However, a possible reduction in the BPC reliability of the BATT-ESS is inevitable due to different charging/discharging levels of this BATT-ESS in the DC MG. To make this assumption clear, the novel reliability analysis of the BPCs in BATT-ESSs is proposed in this paper by taking into account their dynamic and transient scenarios in the DC microgrid. The dynamic-voltage-based failure rate (DVBFR) and the fault-current-based failure rate (FCBFR) respectively from dynamic and fault scenarios of the BPC are two main objectives of the reliability study. These two failure rates are combined with the useful-time-based failure rate (UTBFR) and a Markov-based reliability model to give more holistic reliability evaluation results. Experimental results show that the FCBFR of the BPC in the BATT-ESS is larger than its DVBFR. The reliability of the BPC at the system level could be considerably decreased by multiple repeated dynamic cases. For component-level reliability of the BPC, the DVBFR of diodes is also the least impacted by the dynamic cases. Exponential and logarithmic functions are used to describe approximately the rapidly-increasing trendlines of FCBFRs of power-electronic elements in the BPC under the faulted operation cases. Moreover, reliability indices such as mean-time-to-failure (MTTF), mean-time-between-failures (MTBF), and the reliability index (R) of the BPCs in the BATT-ESSs are also quickly decreased by their fault and dynamic cases.
Household-sized low-voltage (LV) DC microgrids (MGs) are mostly interconnected to a platform that is called a local energy community (LEC). Each household-sized DC MG commonly consists of battery ...energy storage systems (BESSs), solar energy generating systems (SEGSs), AC loads, and LV DC appliances. The different AC loads operate through DC/AC power inverters which are connected to the high-voltage DC (HVDC) common bus in the LEC, while the LV DC appliances operate through DC–DC buck converters (DCBKCs) that are also linked to the same system. The DCBKCs can reduce the operating voltage to a certain level to be adapted to household-sized DC loads. To demonstrate the importance of BKCs in the household-sized LVDC MG, this paper presents the reliability analysis of BKCs by considering all dynamic and faulted operations during their used time. In general, the performance reliability of BKCs could be reduced by several factors including high short-circuit currents, dynamic voltage ripples, power losses, and their used time, which can cause a significant decrease in the power-supply reliability for LVDC loads. For the reliability analysis of BKCs, the primary objective is to formulate the rippled-voltage-dependent failure rate (RVDFR) and the short-circuit-current-dependent failure rate (SCCDFR) in the system. Secondly, a combination of the aforementioned failure rates (FRs) with the operating-time-dependent failure rate (OTDFR) is proposed to determine the system-level reliability of the BKC through a Markov-state transition diagram. Consequently, experiment results of reliability evaluation of the BKC in the DC microgrid show that i) capacitor and inductor components are vulnerable to multiple dynamic cases; ii) the diode is the least affected component of the BKC from random dynamic operations; and iii) faults at the BKC’s output have a significant impact on the working reliability of inductors, switching elements, and capacitors. Influenced by all dynamic and faulted operations during the used time, the BKC’s reliability could decrease to 50% within 6.9 years of usage, while the mean-time-between-failures (MTBF) value rapidly decreases within the first 5 working years.
With the outbreak of the covid-19 pandemic in recent years, Video Stream Analytics technology quickly became a hot topic of discussion across technology forums. As it has appeared, in the pandemic ...situation in recent years, the use of masks when interacting with the community is a must, that's why the research works on mask identification today and more. receiving more and more attention. Understanding the situation, the team conducted facial recognition analysis inside the video to determine if the people appearing in the video were wearing masks. to then apply the trained model into practice. After a period of research, the team has also successfully built a mask recognition system that can generate images and can display the results as real-time video. Especially, the model is trained successful using systemml machine learning system. This is considered a positive result with real-time masked face recognition analysis.
PDF
