Effect of Different Varieties, Processing Methods, Harvesting Times, and Storage Periods on the Quality of Maca

Tingting Xu,Xiaoya Chen,Xiuming Cui,Chengxiao Wang,Lisha Qiu 한국원예학회 2023 원예과학기술지 Vol.41 No.4

Maca, Lepidium meyenii Walpers (Brassicaceae), has been the subject of much research due to its unique biological activity. Maca is widely distributed in Yunnan Province, China, but is not well recognized in the market. In this study, through a chemical analysis, high-performance liquid chromatography (HPLC), and principal component analysis (PCA), the nutritional and bioactive components of different varieties, processing methods, harvesting times, and storage periods of maca were determined and analyzed. The results indicated that whole maca when dried at 35°C, harvested around the winter solstice and planted at an altitude of about 3,000 meters was favorable for the production of nutrients and bioactive components. Compared to black maca, yellow maca had higher levels of glucosinolates, flavonoids, alkaloids and macamides. In addition, a shorter storage period (less than one year) of maca leads to a higher content of bioactive components. The findings here provide a scientific basis for the cultivation and origin processing of maca

Mercury Bioavailability as Affected by Organic Ligand in Aqueous Environment

Xianghua Xu,Wenjuan Shi,Tony Zhuang,Tingting Xu,Steven Ripp,Fumin Menn,Alice Layton,Jie Zhuang,Gary Sayler 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

Research on Stress Reduction Model Based on Transformer

Xin Xu,Yikun Zhao,Ruhao Zhang,Tingting Xu 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.12

People are constantly exposed to stress and anxiety environment, which could contribute to a variety of psychological and physical health problems. Therefore, it is particularly important to identify psychological stress in time and to find a feasible and universal method of stress reduction. This research investigated the influence of different music, such as relaxation music and natural rhythm music, on stress relief based on Electroencephalogram signals. Mental arithmetic test was implemented to create a stressful environment. 23 participants performed the mental arithmetic test with and without music respectively, while their Electroencephalogram signal was recorded. The effect of music on stress relief was verified through stress test questionnaires, including Trait Anxiety Inventory (STAI-6) and Self-Stress Assessment. There was a significant change in the stress test questionnaire values with and without music according to paired t-test (p<0.01). Furthermore, a model based on Transformer for stress level classification from Electroencephalogram signal was proposed. Experimental results showed that the method of listening to relaxation music and natural rhythm music achieved the effect of reducing psychological stress and the proposed model yielded a promising accuracy in classifying the Electroencephalogram signal of mental stress.

A Novel AC/DC Converter Based on Stacked Boost Circuit and Dual-Mode LLC Circuit

Tingting Yao,Yueshi Guan,Fang Li,Yijie Wang,Wei Wang,Dianguo Xu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

In this paper, a AC/DC converter based on stacked Boost circuit and dual-mode LLC circuit is proposed. In the Power Factor Correction (PFC) part, two Boost circuits are stacked to reduce switch voltage stress, also sharing one inductor operating in Boundary Conduction Mode (BCM). In the DC/DC part, a dual-mode LLC circuit is adopted based on two stacked half-bridge structure. The input voltage of LLC resonant tank can double or halve by switching between two operating modes. Hence, the voltage gain of LLC converter can be modified without large operating frequency modulation range. The proposed AC/DC converter can be utilized in widely input voltage variation condition. A 50W prototype is proposed in the laboratory and the experimental results verify the feasibility of the proposed converter.

On compressive behavior of large welded hollow spherical joints with both internal and external stiffeners

Tingting Shu,Xian Xu,Yao-Zhi Luo 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.2

Welded hollow spherical joints are commonly used joints in space grid structures. An internal stiffener is generally adopted to strengthen the joints when large hollow spheres are used. To further strengthen it, external stiffeners can be used at the same time. In this study, axial compression tests are conducted on four full-scale 550 mm spherical joints. The failure modes and strengths of the tested joints are investigated. It shows that the external stiffeners are able to increase the strength of the joint up to 25%. A numerical model for large spherical joints with stiffeners is established and verified against the experimental results. Parametric studies are executed considering six main design factors using the verified model. It is found that the strength of the spherical joint increases as the thickness, height and number of the external stiffeners increase, and the hollow sphere’s diameter has a neglectable effect on the enhancement caused by the external stiffeners. Based on the experimental and numerical results, a practical formula for the compressive bearing capacity of large welded hollow spherical joints with both internal and external stiffeners is proposed. The proposed formula gives a conservative prediction on the compressive capacity of large welded hollow spherical joints with both internal and external stiffeners.

Reliability Evaluation of a Microgrid Considering Its Operating Condition

Xu, Xufeng,Mitra, Joydeep,Wang, Tingting,Mu, Longhua The Korean Institute of Electrical Engineers 2016 Journal of Electrical Engineering & Technology Vol.11 No.1

Microgrids offer several reliability benefits, such as the improvement of load-point reliability and the opportunity for reliability-differentiated services. The primary goal of this work is to investigate the impacts of operating condition on the reliability index for microgrid system. It relies on a component failure rate model which quantifies the relationship between component failure rate and state variables. Some parameters involved are characterized by subjective uncertainty. Thus, fuzzy numbers are introduced to represent such parameters, and an optimization model based on Fuzzy Chance Constrained Programming (FCCP) is established for reliability index calculation. In addition, we present a hybrid algorithm which combines scenario enumeration and fuzzy simulation as a solution tool. The simulations in a microgrid test system show that reliability indices without considering operating condition can often prove to be optimistic. We also investigate two groups of situations, which include the different penetration levels of microsource and different confidence levels. The results support the necessity of considering operating condition for achieving accurate reliability evaluation.

Electrospinning Inorganic/Organic Nanohybridization Membranes with Hydrophobic and Oleophobic Performance

Tingting Zhang,Zihui Li,Ya Liu,Kangjia Ding,Yangfeng Guo,Yiyang Xu,Mengfan Sun,Dongfang Wang,Qian Li 한국섬유공학회 2023 Fibers and polymers Vol.24 No.12

Polytetrafluoroethylene (PTFE) nano-porous membrane has been widely used in various fields due to its excellent thermal stability and chemical stability. However, PTFE nanofiber membranes with simultaneous hydrophobic and oleophobic properties are essential to promote the application of PTFE. Here, based on inorganic/organic nanohybridization, we report a strategy for constructing nanostructures on fibers by adding nanoparticles, such as MOF and ZrO2. The results of FTIR and XRD confirmed MOF was synthesized successfully. At the same time, the SEM results showed UiO-66-(COOH)2 is spherical with an average diameter of 152 nm, and there is no agglomeration, which is suitable for electrospinning. Further, MOF and ZrO2 were payload into PTFE nanofibers. The results of SEM and AFM confirmed nanostructures will be more uniform and pronounced with the increase of UiO-66-(COOH)2 content, and nanostructures are most obvious when the content of UiO-66-(COOH)2 is 15%. The introduced nanostructures can increase the oil contact angle of the PTFE nano-porous membrane to 110° without introducing other groups, and further improve the water contact angle from 133° to 145°. Meanwhile, the introduction of a certain amount of hydrophilia groups can increase the oil contact angle to more than 120°. The simple strategy is of great significance to expand the application of PTFE fiber membrane in dealing with waste water treatment fields.

Anaerobic Ammonium-Oxidizing Bacteria in Cow Manure Composting

( Tingting Wang ),( Lijun Cheng ),( Wenhao Zhang ),( Xiuhong Xu ),( Qingxin Meng ),( Xuewei Sun ),( Huajing Liu ),( Hongtao Li ),( Yu Sun ) 한국미생물생명공학회(구 한국산업미생물학회) 2017 Journal of microbiology and biotechnology Vol.27 No.7

Composting is widely used to transform waste into valuable agricultural organic fertilizer. Anaerobic ammonium-oxidizing (anammox) bacteria play an important role in the global nitrogen cycle, but their role in composting remains poorly understood. In the present study, the community structure, diversity, and abundance of anammox bacteria were analyzed using cloning and sequencing methods by targeting the 16S rRNA gene and the hydrazine oxidase gene (hzo) in samples isolated from compost produced from cow manure and rice straw. A total of 25 operational taxonomic units were classified based on 16S rRNA gene clone libraries, and 14 operational taxonomic units were classified based on hzo gene clone libraries. The phylogenetic tree analysis of the 16S rRNA gene and deduced HZO protein sequences from the corresponding encoding genes indicated that the majority of the obtained clones were related to the known anammox bacteria Candidatus “Brocadia,” Candidatus “Kuenenia,” and Candidatus “Scalindua.” The abundances of anammox bacteria were determined by quantitative PCR, and between 2.13 × 10⁵ and 1.15 × 10⁶ 16S rRNA gene copies per gram of compost were found. This study provides the first demonstration of the existence of anammox bacteria with limited diversity in cow manure composting.

Association of MMP-9 C-1562T polymorphism with risk of Henoch-Schönlein purpura nephritis in children of southeast China

Jinwen Xu,Liping Zhao,Hongxia Zhou,Tingting Ge,Lin Zhang 한국유전학회 2017 Genes & Genomics Vol.39 No.4

Henoch-Schönlein purpura nephritis (HSPN) is the most prevalent vasculitis in childhood worldwide. Although the etiology of HSPN is not yet fully elucidated, it is believed to be closely related with infections and genetic predispositions. In this study, a cohort of children from southeast China, including 108 healthy controls and 184 patients were involved in. We scanned the promoter region and the whole gene for genetic variations. A C/T transition located in the promoter region of MMP-9 gene, C-1562T was identified. Subjects were genotyped by using SNaPshot sequencing and the frequencies of CC, CT and TT genotypes were 43, 33 and 24% in patients and 53, 37 and 10% in healthy controls. Allele distribution was found to be in Hardy–Weinberg equilibrium (P = 0.17). Association analysis revealed that the polymorphism was significantly related with HSPN risk (P < 0.05) and T allele was shown to be a risk factor (P = 0.003, odds ratio (OR) 1.63, 95% confidence interval (CI) 1.13–2.34). Additionally, we measured the serum MMP-9 concentration and quantified the mRNA expression. Results showed that an elevated protein level was observed in patients compared with controls in both ELISA (P = 0.0029, 136.5 μg/L vs. 103.9 μg/L) and Western blot assays. Furthermore, we also detected 1.93-fold increase in the mRNA transcription in patients carrying homozygous TT genotype, indicating enhanced promoter activity caused by the polymorphism. Based on the incidence risk, a cut-off value of serum MMP-9 served as HSPN diagnosis was suggested at 155 μg/L. Conclusively, our findings suggested that MMP-9 polymorphism was significantly associated with HSPN susceptibility, and C-1562T T allele contributed to HSPN development.

Reliability Evaluation of a Microgrid Considering Its Operating Condition

Xufeng Xu,Joydeep Mitra,Tingting Wang,Longhua Mu 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.1

Microgrids offer several reliability benefits, such as the improvement of load-point reliability and the opportunity for reliability-differentiated services. The primary goal of this work is to investigate the impacts of operating condition on the reliability index for microgrid system. It relies on a component failure rate model which quantifies the relationship between component failure rate and state variables. Some parameters involved are characterized by subjective uncertainty. Thus, fuzzy numbers are introduced to represent such parameters, and an optimization model based on Fuzzy Chance Constrained Programming (FCCP) is established for reliability index calculation. In addition, we present a hybrid algorithm which combines scenario enumeration and fuzzy simulation as a solution tool. The simulations in a microgrid test system show that reliability indices without considering operating condition can often prove to be optimistic. We also investigate two groups of situations, which include the different penetration levels of microsource and different confidence levels. The results support the necessity of considering operating condition for achieving accurate reliability evaluation.