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Background: To analyze the risk factors for the development of avascular necrosis (AVN) of the femoral head after reduction surgery in children with developmental hip dysplasia (DDH), and to establish a prediction nomogram. Methods: The clinical data of 134 children with DDH (169 hips) treated with closure reduction or open reduction from December 2016 to December 2019 were retrospectively analyzed. Independent risk factors for AVN after DDH reduction being combined with cast external immobilization were determined by univariate analysis and multivariate logistic regression and used to generate nomograms predicting the occurrence of AVN. Results: A total of 169 hip joints in 134 children met the inclusion criteria, with a mean age at surgery of 10.7 ± 4.56 months (range: 4–22 months) and a mean follow-up duration of 38.32 ± 27.00 months (range: 12–94 months). AVN developed in 42 hip joints (24.9%); univariate analysis showed that the International Hip Dysplasia Institute (IHDI) grade, preoperative development of the femoral head ossification nucleus, cartilage acetabular index, femoral head to acetabular Y-shaped cartilage distance, residual acetabular dysplasia, acetabular abduction angle exceeding 60°, and the final follow-up acetabular index (AI) were associated with the development of AVN (P < 0.05). Multivariate logistic regression analysis showed that the preoperative IHDI grade, development of the femoral head ossification nucleus, acetabular abduction angle exceeding 60°, and the final follow-up AI were independent risk factors for AVN development (P < 0.05). Internal validation of the Nomogram prediction model showed a consistency index of 0.833. Conclusion: Preoperative IHDI grade, preoperative development of the femoral head ossification nucleus, final AI, and acetabular abduction angle exceeding 60° are risk factors for AVN development. This study successfully constructed a Nomogram prediction model for AVN after casting surgery for DDH that can predict the occurrence of AVN after casting surgery for DDH. [ABSTRACT FROM AUTHOR]

γ-Aminobutyric acid (GABA) is a crucial neurotransmitter with wide application prospects. In this study, we focused on a GABA-producing strain from a traditional Chinese fermented beverage system. Among the six isolates, Lactobacillus hilgardii GZ2 exhibited the greatest ability to produce GABA in the traditional Chinese fermented beverage system. To increase GABA production, we optimized carbon sources, nitrogen sources, temperature, pH, and monosodium glutamate and glucose concentrations and conducted fed-batch fermentation. The best carbon and nitrogen sources for GABA production and cell growth were glucose, yeast extract and tryptone. Gradual increases in GABA were observed as the glucose and monosodium glutamate concentrations increased from 10 g/L to 50 g/L. During fed-batch fermentation, lactic acid was used to maintain the pH at 5.56, and after feeding with 0.03 g/mL glucose and 0.4 g/mL sodium glutamate for 72 h, the GABA yield reached 239 g/L. This novel high-GABA-producing strain holds great potential for the industrial production of GABA, as well as the development of health-promoting functional foods and medical fields. [ABSTRACT FROM AUTHOR]

Motivation Retrosynthesis is a critical task in drug discovery, aimed at finding a viable pathway for synthesizing a given target molecule. Many existing approaches frame this task as a graph-generating problem. Specifically, these methods first identify the reaction center, and break a targeted molecule accordingly to generate the synthons. Reactants are generated by either adding atoms sequentially to synthon graphs or by directly adding appropriate leaving groups. However, both of these strategies have limitations. Adding atoms results in a long prediction sequence that increases the complexity of generation, while adding leaving groups only considers those in the training set, which leads to poor generalization. Results In this paper, we propose a novel end-to-end graph generation model for retrosynthesis prediction, which sequentially identifies the reaction center, generates the synthons, and adds motifs to the synthons to generate reactants. Given that chemically meaningful motifs fall between the size of atoms and leaving groups, our model achieves lower prediction complexity than adding atoms and demonstrates superior performance than adding leaving groups. We evaluate our proposed model on a benchmark dataset and show that it significantly outperforms previous state-of-the-art models. Furthermore, we conduct ablation studies to investigate the contribution of each component of our proposed model to the overall performance on benchmark datasets. Experiment results demonstrate the effectiveness of our model in predicting retrosynthesis pathways and suggest its potential as a valuable tool in drug discovery. Availability and implementation All code and data are available at https://github.com/szu-ljh2020/MARS. [ABSTRACT FROM AUTHOR]

This article explores the relationship between extreme temperatures and allergic asthma in a mouse model. The study found that exposure to extreme temperatures, particularly high temperatures, promoted the development of allergic asthma in mice. It was observed that extreme temperatures exacerbated oxidative stress and airway inflammation in the mice, leading to increased asthma symptoms. The study also identified the upregulation of pro-inflammatory cytokines and TRP channel receptors as potential mechanisms through which extreme temperatures impact asthma. Overall, the findings highlight the importance of understanding the mechanisms behind the association between extreme weather events and allergic asthma. [Extracted from the article]

Silkworm pupae are a major by-product of the silkworm mulberry industry, and the high content of tri-alpha-linolenin (glyceryl tri-alpha-linolenate, LnLnLn) in silkworm pupae oil makes it an excellent essential fatty acid supplement. However, the complex triglyceride composition of silkworm pupae oil limits its absorption and utilization by the human body. In this study, a sequential simulated moving bed (SSMB) approach for continuous separation was presented to recover the high-value tri-alpha-linolenin monomer from silkworm pupae oil. C18 particles were used as the stationary phase. Acetonitrile and isopropanol were used as the elution mobile phases. Under optimal SSMB conditions, the purity and yield of the extracted products were 95.15±2.06% and 2.14±0.06 mg/mL, respectively. In comparison to the conventional extraction approach, the yield of tri-alpha-linolenin separated by SSMB was 26.7 times greater, the dose of eluent was lowered by 2 times, and the eluent could be recycled. To validate the experimental parameters, a mass transfer diffusion model was used. The molecular diffusion coefficient of tri-alpha-linolenin was 2.61×10−6 cm2/s, the axial diffusion coefficient was 2.61×10−6+7.56×10−3μ, and the mass transfer diffusion coefficient was 0.87 s−1. The correlation coefficient between the model and the actual measured values was 0.9688. Consequently, the separation of tri-alpha-linolenin monomer in silkworm pupae oil by sequential simulated moving bed chromatography column can be reasonably described and predicted by this model. In conclusion, a novel approach to the commercialization of insect oils was developed by the extraction and purification of tri-alpha-linolenin from silkworm pupae oil using the SSMB approach. [ABSTRACT FROM AUTHOR]

Basic leucine zipper (bZIP) transcription factors (TFs) are one of the largest families involved in plant physiological processes such as biotic and abiotic responses, growth, and development, etc. In this study, 66 members of the bZIP family were identified in Bletilla striata, which were divided into 10 groups based on their phylogenetic relationships with AtbZIPs. A structural analysis of BsbZIPs revealed significant intron–exon differences among BsbZIPs. A total of 63 bZIP genes were distributed across 16 chromosomes in B. striata. The tissue-specific and germination stage expression patterns of BsbZIPs were based on RNA-seq. Stress-responsive expression analysis revealed that partial BsbZIPs were highly expressed under low temperatures, wounding, oxidative stress, and GA treatments. Furthermore, subcellular localization studies indicated that BsbZIP13 was localized in the nucleus. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays suggested that BsbZIP13 could interact with multiple BsSnRK2s. The results of this study provide insightful data regarding bZIP TF as one of the stress response regulators in B. striata, while providing a theoretical basis for transgenic and functional studies of the bZIP gene family in B. striata. [ABSTRACT FROM AUTHOR]

Energy transfer accompanying with current is usually described by using Poynting's vector. Here, combining Kirchhoff's law, Joule's law and Slepian's postulation, we demonstrate that, for the case of a current travels along a wire, component of total energy flow flux parallel to the wire (CTEFFPW) may be equivalently described by using product of current intensity and electric potential (voltage), furthermore, the law of conversion and conservation of energy accompanying with current, which is equivalent to Poynting's theorem, may be obtained based on circuit method. Noting that product of current intensity and voltage relates to CTEFFPW instead of the electric power, physical meaning of usual definitions of powers adopted in electric power theory are readdressed. Our work may provide possibility to achieve the long-time expectation that power properties of power systems are described on the basis of Poynting's theorem and Poynting's vector, and to address the unsolved problems arised in the electric power theory. [ABSTRACT FROM AUTHOR]

The high cell density, immobilization and stability of biofilms are ideal characteristics for bacteria in resisting antibiotic therapy. CsgD is a transcription activating factor that regulates the synthesis of curly fimbriae and cellulose in Escherichia coli, thereby enhancing bacterial adhesion and promoting biofilm formation. To investigate the role of CsgD in biofilm formation and stress resistance in bacteria, the csgD deletion mutant ΔcsgD was successfully constructed from the engineered strain E. coli BL21(DE3) using the CRISPR/Cas9 gene-editing system. The results demonstrated that the biofilm of ΔcsgD decreased by 70.07% (p < 0.05). Additionally, the mobility and adhesion of ΔcsgD were inhibited due to the decrease in curly fimbriae and extracellular polymeric substances. Furthermore, ΔcsgD exhibited a significantly decreased resistance to acid, alkali and osmotic stress conditions (p < 0.05). RNA-Seq results revealed 491 differentially expressed genes between the parent strain and ΔcsgD, with enrichment primarily observed in metabolism-related processes as well as cell membrane structure and catalytic activity categories. Moreover, CsgD influenced the expression of biofilm and stress response genes pgaA, motB, fimA, fimC, iraP, ompA, osmC, sufE and elaB, indicating that the CsgD participated in the resistance of E. coli by regulating the expression of biofilm and stress response. In brief, the transcription factor CsgD plays a key role in the stress resistance of E. coli, and is a potential target for treating and controlling biofilm. [ABSTRACT FROM AUTHOR]

Background: Pneumonia is a common disease worldwide in preschool children. Despite its large population size, China has had no comprehensive study of the national prevalence, risk factors, and management of pneumonia among preschool children. We therefore investigated the prevalence of pneumonia among preschool children in Chinese seven representative cities, and explore the possible risk factors of pneumonia on children, with a view to calling the world's attention to childhood pneumonia to reduce the prevalence of childhood pneumonia. Methods: Two group samples of 63,663 and 52,812 preschool children were recruited from 2011 and 2019 surveys, respectively. Which were derived from the cross-sectional China, Children, Homes, Health (CCHH) study using a multi-stage stratified sampling method. This survey was conducted in kindergartens in seven representative cities. Exclusion criteria were younger than 2 years old or older than 8 years old, non-permanent population, basic information such as gender, date of birth and breast feeding is incomplete. Pneumonia was determined on the basis of parents reported history of clearly diagnosed by the physician. All participants were assessed with a standard questionnaire. Risk factors for pneumonia, and association between pneumonia and other respiratory diseases were examined by multivariable-adjusted analyses done in all participants for whom data on the variables of interest were available. Disease management was evaluated by the parents' reported history of physician diagnosis, longitudinal comparison of risk factors in 2011 and 2019. Results: In 2011 and 2019, 31,277 (16,152 boys and 15,125 girls) and 32,016 (16,621 boys and 15,395 girls) preschool children aged at 2–8 of permanent population completed the questionnaire, respectively, and were thus included in the final analysis. The findings showed that the age-adjusted prevalence of pneumonia in children was 32.7% in 2011 and 26.4% in 2019. In 2011, girls (odds ratio [OR] 0.91, 95%CI [confidence interval]0.87–0.96; p = 0.0002), rural (0.85, 0.73–0.99; p = 0.0387), duration of breastfeeding ≥ 6 months(0.83, 0.79–0.88; p < 0.0001), birth weight (g) ≥ 4000 (0.88, 0.80–0.97; p = 0.0125), frequency of putting bedding to sunshine (Often) (0.82, 0.71–0.94; p = 0.0049), cooking fuel type (electricity) (0.87, 0.80–0.94; p = 0.0005), indoor use air-conditioning (0.85, 0.80–0.90; p < 0.0001) were associated with a reduced risk of childhood pneumonia. Age (4–6) (1.11, 1.03–1.20; p = 0.0052), parental smoking (one) (1.12, 1.07–1.18; p < 0.0001), used antibiotics (2.71, 2.52–2.90; p < 0.0001), history of parental allergy (one and two) (1.21, 1.12–1.32; p < 0.0001 and 1.33, 1.04–1.69; p = 0.0203), indoor dampness (1.24, 1.15–1.33; p < 0.0001), home interior decoration (1.11, 1.04–1.19; p = 0.0013), Wall painting materials (Paint) (1.16, 1.04–1.29; p = 0.0084), flooring materials (Laminate / Composite wood) (1.08, 1.02–1.16; p = 0.0126), indoor heating mode(Central heating)(1.18, 1.07–1.30, p = 0.0090), asthma (2.38, 2.17–2.61; p < 0.0001), allergic rhinitis (1.36, 1.25–1.47; p < 0.0001), wheezing (1.64, 1.55–1.74; p < 0.0001) were associated with an elevated risk of childhood pneumonia; pneumonia was associated with an elevated risk of childhood asthma (2.53, 2.31–2.78; p < 0.0001), allergic rhinitis (1.41, 1.29–1.53; p < 0.0001) and wheezing (1.64, 1.55–1.74; p < 0.0001). In 2019, girls (0.92, 0.87–0.97; p = 0.0019), duration of breastfeeding ≥ 6 months (0.92, 0.87–0.97; p = 0.0031), used antibiotics (0.22, 0.21–0.24; p < 0.0001), cooking fuel type (Other) (0.40, 0.23–0.63; p = 0.0003), indoor use air-conditioning (0.89, 0.83–0.95; p = 0.0009) were associated with a reduced risk of childhood pneumonia. Urbanisation (Suburb) (1.10, 1.02–1.18; p = 0.0093), premature birth (1.29, 1.08–1.55; p = 0.0051), birth weight (g) < 2500 (1.17, 1.02–1.35; p = 0.0284), parental smoking (1.30, 1.23–1.38; p < 0.0001), history of parental asthma (One) (1.23, 1.03–1.46; p = 0.0202), history of parental allergy (one and two) (1.20, 1.13–1.27; p < 0.0001 and 1.22, 1.08–1.37; p = 0.0014), cooking fuel type (Coal) (1.58, 1.02–2.52; p = 0.0356), indoor dampness (1.16, 1.08–1.24; p < 0.0001), asthma (1.88, 1.64–2.15; p < 0.0001), allergic rhinitis (1.57, 1.45–1.69; p < 0.0001), wheezing (2.43, 2.20–2.68; p < 0.0001) were associated with an elevated risk of childhood pneumonia; pneumonia was associated with an elevated risk of childhood asthma (1.96, 1.72–2.25; p < 0.0001), allergic rhinitis (1.60, 1.48–1.73; p < 0.0001) and wheezing (2.49, 2.25–2.75; p < 0.0001). Conclusions: Pneumonia is prevalent among preschool children in China, and it affects other childhood respiratory diseases. Although the prevalence of pneumonia in Chinese children shows a decreasing trend in 2019 compared to 2011, a well-established management system is still needed to further reduce the prevalence of pneumonia and reduce the burden of disease in children. [ABSTRACT FROM AUTHOR]

β-Ga2O3 thin films with both a 45 nm Si-doped conductive epilayer and unintentionally doped epilayer were grown on c-plane sapphire substrate by metalorganic chemical vapor deposition. β-Ga2O3 based metal–oxide–semiconductor field-effect transistors (MOSFETs) were fabricated with gate recess depths of 20 nm and 40 nm (it indicated gate depth with 70 nm and 50 nm, respective), respectively, and without said recessing process. The conductivity of β-Ga2O3 epilayers was improved through low in situ doping using a tetraethoxysilane precursor to increase MOSFET forward current density. After recessing, MOSFET operation was transferred from depletion to enhanced mode. In this study, the maximum breakdown voltage of the recessed 40 nm transistor was 770 V. The etching depth of a recessed-gate device demonstrates its influence on device electrical performance. [ABSTRACT FROM AUTHOR]

In this work, we demonstrated Ga2O3-based power MOSFETs grown on c-plane sapphire substrates using in-situ TEOS doping for the first time. The β-Ga2O3:Si epitaxial layers were formed by the metalorganic chemical vapor deposition (MOCVD) with a TEOS as a dopant source. The depletion-mode Ga2O3 power MOSFETs are fabricated and characterized, showing the increase of the current, transconductance, and breakdown voltage at 150 °C. In addition, the sample with the TEOS flow rate of 20 sccm exhibited a breakdown voltage of more than 400 V at RT and 150 °C, indicating that the in-situ Si doping by TEOS in MOCVD is a promising method for Ga2O3 power MOSFETs. [ABSTRACT FROM AUTHOR]

Microfluidic biocatalytic reactors have attracted widespread attention in recent years, but the production cost is generally high, which makes it difficult to meet the needs of large-scale industrial production. Developing a low-cost, green fluid reactor has become an urgent requirement. Here, inspired by the three-dimensional hierarchical structure of natural wood, a cellulose-based bionic microfluidic biocatalytic reactor with vertically aligned channels and a porous inner wall is reported for the continuous fluid catalytic conversion of polydatin to resveratrol. NiO nanoparticles were immobilized on cellulose-based bionic materials as metal arms to adsorb poly-histidine-tagged enzymes to form a stable and efficient biocatalytic reactor. Due to the unidirectionally aligned channels and porous inner wall, the fluid in different channels of the bionic xylem reactor is disturbed through the porous inner wall, which greatly prolongs the residence time for the fluid inside the reactor and increases the probability for contact with the enzyme, improving the internal mass and heat transfer efficiency to achieve high catalytic activity (98.69% treatment efficiency) and excellent stability (maintain a conversion rate of more than 90% within 15 days). Because of the good and stable enzyme immobilization and high catalytic activity of the reactor, it can greatly simplify industrial upstream and downstream production and has broad application prospects for catalytic reactions. [ABSTRACT FROM AUTHOR]

Green and low-carbon rural development (GLRD) is becoming an important way to explore sustainable development in rural areas of China. It is significant for the sustainable development of the rural economy and of society to build a rural carbon sink system, advocate low-carbon emissions in rural areas, and promote the development of rural green industries and rural transformation. In this study, the existing knowledge system of GLRD was analyzed using CiteSpace. Keywords related to GLRD and their occurrence frequency were identified using keyword co-occurrence analysis. The knowledge evolution stages of GLRD were explored using citation burst analysis. Thus, the evolution of the research related to GLRD was revealed. The summary of Chinese GLRD-related research literature shows that: (1) according to the CiteSpace analysis, the GLRD research can be divided into three stages: starting, rising, and expanding and deepening; (2) GLRD research has focused on low-carbon development, green development, and then green and low-carbon integrated development, thus forming three major research content systems; (3) GLRD's research content gradually became rich, as over time, the research focus became increasingly prominent and research integration was gradually strengthened; (4) the GLRD literature still has some limitations, e.g., nonunified measurement standards, insufficient research depth and practical significance, and relatively weak innovative policy research; (5) future research should strengthen the scientific evaluation and prediction of rural green and low-carbon functions. The industrial development pathways and regional characteristic modes of GLRD should be further studied. Innovative GLRD policies should be proposed to provide a theoretical basis and decision-making reference for GLRD and construction. [ABSTRACT FROM AUTHOR]

A cohort case–control study was conducted in XiangYa Hospital, Changsha, China, which involved 305 patients and 399 healthy women, from June 2010 to December 2018, to evaluate the association between Chinese women's short- and long-term exposure to industrial air pollutant, SO2 and gynaecological cancer (GC). We obtained personal and family information from the XiangYa Hospital electronic computer medical records. Using data obtained from the air quality monitoring stations in Changsha, we estimated each woman's exposure to the industrial air pollutant, sulphur dioxide (SO2), for different time windows, including the past 1, 5, 10 and 15 years before diagnosis of the disease. A multiple logistic regression model was used to assess the association between GC and SO2 exposure. GC was significantly associated with long-term SO2 exposure, with adjusted odds ratio (95% confidence interval) = 1.56 (1.10–2.21) and 1.81 (1.07–3.06) for a per interquartile range increase in the past 10 and 15 years, respectively. Sensitivity analysis showed that different groups reacted in different ways to long-term SO2 exposure. We concluded that long-term exposure to high concentration of industrial pollutant, SO2 is associated with the development of GC. This finding has implications for the prevention and reduction of GC. [ABSTRACT FROM AUTHOR]

Cremastraappendiculata (Orchidaceae) is a perennial medicinal herb, which is included in the national second-class protected plant catalog in China. Due to the influences of climate change and anthropogenic activities, in conjunction with soaring commercial prices, the wild sources of C.appendiculata have been drastically reduced and are in danger of extinction. Consequently, it is important to predict the distribution of potentially suitable growth/propagation areas for C.appendiculata under the backdrop of climate change for its protection and sustainable use. For this study, an optimized maximum entropy model was employed to analyze the distribution patterns and changes of potentially suitable regions for C.appendiculata during different periods since the Last Glacial Maximum (LGM, 18–24 ka). Based on multiple climate change scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5), the distribution range of C. appendiculata was predicted for the 2050s (average for 2041–2060), 2070s (average for 2061–2080), and 2090s (average for 2081–2100). The results revealed that during the LGM period, the highly suitable growth area for C.appendiculata was 0.28 × 104 km2, which accounted for only 3.26% of the current highly suitable growth area. During the mid-Holocene (MH, 6 ka) period, the area of highly suitable regions increased to 8.38 × 104 km2, which accounted for 99.30% of the present highly suitable growth area. Further, the cumulative existing potentially suitable growth area for C. appendiculata is 213.9 × 104 km2, which accounts for 22.28% of China's territory. Of these lands, the low, medium, and high suitable areas are 147.76 × 104 km2, 57.71 × 104 km2, and 8.44 × 104 km2, respectively. The highly suitable areas are primarily distributed across Sichuan, Gansu, Shaanxi, Chongqing, Guizhou, Hubei, and Anhui Provinces. Moreover, in the future the potentially suitable growth areas for C. appendiculata will decrease to varying degrees. Further, the results of this study found that the relatively low impact areas for C. appendiculata were mainly distributed across Shaanxi, Sichuan, Chongqing, and Guizhou Provinces. Centroid transfer analysis indicated that the center of potentially suitable growth areas for C.appendiculata shifted to the northwest in SSP2-4.5 and SSP3-7.0, while they initially shifted to the northwest and then to the southeast in SSP1-2.6 and SSP5-8.5. [ABSTRACT FROM AUTHOR]

SWEETs (sugars will eventually be exported transporters), a well-known class of sugar transporters, are involved in plant growth and development, sugar transport, biotic and abiotic stresses, etc. However, to date, there have been few investigations of SWEETs in Orchidaceae. In this study, 23 SWEET genes were identified in Bletilla striata for the first time, with an MtN3/saliva conserved domain, and were divided into four subgroups by phylogenetic tree. The same subfamily members had similar gene structures and motifs. Multiple cis-elements related to sugar and environmental stresses were found in the promoter region. Further, 21 genes were localized on 11 chromosomes and 2 paralogous pairs were found via intraspecific collinearity analysis. Expression profiling results showed that BsSWEETs were tissue-specific. It also revealed that BsSWEET10 and BsSWEET18 were responsive to low temperature and oxidative stresses. In addition, subcellular localization study indicated that BsSWEET15 and BsSWEET16 were localized in the cell membrane. This study provided important clues for the in-depth elucidation of the sugar transport mechanism of BsSWEET genes and their functional roles in response to abiotic stresses. [ABSTRACT FROM AUTHOR]

The main target of retrosynthesis is to recursively decompose desired molecules into available building blocks. Existing template-based retrosynthesis methods follow a template selection stereotype and suffer from limited training templates, which prevents them from discovering novel reactions. To overcome this limitation, we propose an innovative retrosynthesis prediction framework that can compose novel templates beyond training templates. As far as we know, this is the first method that uses machine learning to compose reaction templates for retrosynthesis prediction. Besides, we propose an effective reactant candidate scoring model that can capture atom-level transformations, which helps our method outperform previous methods on the USPTO-50K dataset. Experimental results show that our method can produce novel templates for 15 USPTO-50K test reactions that are not covered by training templates. We have released our source implementation. [ABSTRACT FROM AUTHOR]

Boron is an essential element for autoinducer-2 (AI-2) synthesis of quorum sensing (QS) system, which affects bacterial collective behavior. As a living biocatalyst, biofilms can stably catalyze the activity of intracellular enzymes. However, it is unclear how boron affects biofilm formation in E. coli, particularly recombinant E. coli with intracellular enzymes. This study screened different boron derivatives to explore their effect on biofilm formation. The stress response of biofilm formation to boron was illuminated by analyzing AI-2 activity, extracellular polymeric substances (EPS) composition, gene expression levels, etc. Results showed that boron derivatives promote AI-2 activity in QS system. After treatment with H3BO3 (0.6 mM), the AI-2 activity increased by 65.99%, while boron derivatives increased the biomass biofilms in the order H3BO3 > NaBO2 > Na2B4O7 > NaBO3. Moreover, treatment with H3BO3 (0.6 mM) increased biomass by 88.54%. Meanwhile, AI-2 activity had a linear correlation with polysaccharides and protein of EPS at 0–0.6 mM H3BO3 and NaBO2 (R2 > 0.8). Furthermore, H3BO3 upregulated the expression levels of biofilm formation genes, quorum sensing genes, and flagellar movement genes. These findings demonstrated that boron promoted biofilm formation by upregulating the expression levels of biofilm-related genes, improving the QS system AI-2 activity, and increasing EPS secretion in E. coli. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has been causing serious disasters to mankind. The incubation period is a key parameter for epidemic control and also an important basis for epidemic prediction, but its distribution law remains unclear. This paper analyzed the epidemiological information of 787 confirmed non-Wuhan resident cases, and systematically studied the characteristics of the incubation period of COVID-19 based on the interval-censored data estimation method. The results show that the incubation period of COVID-19 approximately conforms to the Gamma distribution with a mean value of 7.8 (95%CI:7.4–8.5) days and a median value of 7.0 (95%CI:6.7–7.3) days. The incubation period was positively correlated with age and negatively correlated with disease severity. Female cases presented a slightly higher incubation period than that of males. The proportion of infected persons who developed symptoms within 14 days was 91.6%. These results are of great significance to the prevention and control of the COVID-19 pandemic. [ABSTRACT FROM AUTHOR]

As a representative medicinal plant in the Orchidaceae, Bletilla striata plays a variety of pharmacological roles in the clinic. However, the emergence of counterfeit species is affecting the basic medicinal materials source identification process, for which Bletilla ochracea and Oreorchis foliosa of the Orchidaceae are two representative species. For this study, 13 representative B. striata samples, three B. ochracea samples and three O. foliosa samples were selected for the systematic determination of polysaccharide yields and monosaccharide composition, and further detection of secondary metabolites by HPLC–MS. The results revealed that there was a significant difference in the yields of polysaccharides between B. striata and B. ochracea (p = 0.006). Although the polysaccharides of both species were composed of glucose and mannose, the molar ratio of the two monosaccharides was different, suggesting that the structures of the polysaccharides were different. The metabolomics results showed that there were no differences in the types of metabolites between B. striata and B. ochracea; however, there were differences in the contents of these metabolites. Although there was no significant difference in the polysaccharide yields of B. striata and O. foliosa (p = 0.074) and the monosaccharide composition was the same (glucose and mannose), many different metabolites were screened out between them: six compounds such as C36H34O11 existed only in B. striata, while substance C39H54O22 was unique to O. foliosa. Therefore, based on the analysis of the polysaccharide content and monosaccharide composition, combined with phase metabolomics research, a preliminary distinction between B. striata, B. ochracea and O. foliosa was achieved. [ABSTRACT FROM AUTHOR]

Common cold is usually considered to be associated with outdoor climate, but the evidence linking with indoor environmental factors is lacking. The role of indoor renovations during which critical timing window on childhood common cold remains unclear. Therefore, we investigated the effect of exposure to new furniture and/or redecoration during prenatal and postnatal periods on the occurrence and duration of common cold in preschool children. We conducted a retrospective cohort study of 39 782 children aged 3–6 years in seven cities of China. The occurrence and duration of common cold in children, and their lifetime exposures to indoor new furniture and redecoration (including pregnancy, the first year of life, and after one year old) were assessed using a questionnaire administered by the parents. Associations between high frequency (>5 colds) and long duration (≥2 weeks per cold) of common cold during past 12 months and exposure to indoor new furniture/redecoration were examined by logistic regression models in terms of odds ratio (OR) and 95% confidence interval (CI). We found that the prevalence of high frequency and long duration of common cold in preschool children in China were, respectively, 9.2% and 11.9%. Frequent common cold was significantly associated with exposure to indoor new furniture/redecoration during pregnancy, first year, and after 1 year old, respectively, with the ORs (95% CI) = 1.25 (1.12–1.39), 1.11 (1.00–1.25), and 1.09 (1.01–1.18). Furthermore, childhood long duration per cold was associated with exposure to indoor new furniture/redecoration during pregnancy with OR (95% CI) of 1.14 (1.03–1.25) but not with postnatal exposure. We identified that prenatal exposure to home renovation was more critical than postnatal exposure for an increased risk of high frequency and long duration of common cold. Sensitivity analysis showed that the association between prenatal exposure to indoor renovations and the risk of childhood common cold was consistent and robust, and the associations were modified by some personal and indoor environmental factors. Our findings indicated that prenatal and postnatal exposure to home renovation played an important role in the risk of childhood common cold, supporting the hypothesis of "fetal origin of childhood infection." [ABSTRACT FROM AUTHOR]

Ziziphus spinosa (Bunge) H.H. Hu ex F.H. Chen is a woody plant species of the family Rhamnaceae (order Rhamnales) that possesses high nutritional and medicinal value. Predicting the effects of climate change on the distribution of Z. spinosa is of great significance for the investigation, protection, and exploitation of this germplasm resource. For this study, optimized maximum entropy models were employed to predict the distribution patterns and changes of its present (1970–2000) and future (2050s, 2070s, and 2090s) potential suitable regions in China under multiple climate scenarios (SSP1‐2.6, SSP2‐4.5, SSP3‐7.0 & SSP5‐8.5). The results revealed that the total area of the present potential suitable region for Z. spinosa is 162.60 × 104 km2, which accounts for 16.94% of China's territory. Within this area, the regions having low, medium, and high suitability were 80.14 × 104 km2, 81.50 × 104 km2, and 0.96 × 104 km2, respectively, with the high suitability regions being distributed primarily in Shanxi, Hebei, and Beijing Provinces. Except for SSP‐1‐2.6‐2070s, SSP‐5‐8.5‐2070s, and SSP‐5‐8.5‐2090s, the suitable areas for Z. spinosa in the future increased to different degrees. Meanwhile, considering the distribution of Z. spinosa during different periods and under different climate scenarios, our study predicted that the low impact areas of Z. spinosa were mainly restricted to Shanxi, Shaanxi, Ningxia, Gansu, Liaoning, Inner Mongolia, and Jilin Provinces. The results of core distributional shifts showed that, except for SSP1‐2.6, the center of the potential suitable region of Z. spinosa exhibited a trend of gradually shifting to the northwest. [ABSTRACT FROM AUTHOR]

To investigate the role of different pattern of ambient air pollutants exposure during early life on childhood pneumonia, we conducted a retrospective cohort study of 3226 preschool children aged three to six years in Shenzhen, China during 2015 to 2016. Each child's exposure to three main air pollutants (PM10, SO2 and NO2) was calculated by the inverse distance weighted method. Multiple logistic regression analysis was used to investigate the pneumonia risk of early life exposure to air pollution. A relatively high prevalence of pneumonia (24.3%) among preschool children in Shenzhen was significantly associated with exposure to PM10 and SO2 during the first year of life, with adjusted odds ratios = 1.24 (1.05, 1.46) and 1.20 (1.05, 1.38) respectively. However, we observed no relationship between NO2 exposure and childhood pneumonia in pregnancy and first year of life. Sensitivity analysis suggested that boys, younger children (three to four years), non-preterm children, children without parental atopy and with exposure to environmental tobacco smoke were more susceptible to the impact of exposure to PM10 and SO2 on their suffering of pneumonia during their first year of life. Early-postnatal exposure to classical air pollution at low concentration during the first year of life can have an important role in enhancing the risk of childhood pneumonia, especially with the sensitive population. [ABSTRACT FROM AUTHOR]

A questionnaire survey on dermal symptoms and home environment was performed in eight Chinese cities (40 279 participants). Data on city level temperature, precipitation, PM10, NO2, and gross domestic product (GDP) per capita were collected. In total, 2.2% had eczema, 2.4% facial erythema (FE) and 2.6% seborrheic dermatitis symptoms (SD). Higher temperature was associated with eczema (OR = 1.09). Higher GDP per capita was related to less SD. Higher PM10 was related to SD. Suburban living was protective for eczema (OR = 0.77) (vs. urban). Living in old buildings (built before 1991) was related to eczema (OR = 1.42). Living near heavily trafficked roads was related to FE (OR = 1.33) and SD (OR = 1.35). Having new furniture was related to all symptoms (OR = 1.26–1.47). Burning mosquito coils (OR = 1.37–1.57) and incense (OR = 1.33–1.37) were associated with eczema, FE, or SD. Presence of cockroaches and rats/mice was associated with FE or SD (OR = 1.31–1.40). Using air conditioner, daily cleaning and frequently exposing bedding to sunshine were protective (OR = 0.60–0.83). In conclusion, higher temperature, higher PM10, urban living, living near heavily trafficked roads, old buildings, new furniture, burning mosquito coils and incense, and presence of cockroaches/rats/mice increased the risk of eczema, FE, or SD. Higher GDP, air conditioner, daily cleaning, and exposing bedding to sunshine were protective. [ABSTRACT FROM AUTHOR]

An inertia identification approach has been proposed for diesel generators by using the modified load rejection procedures. Large frequency deviation problems often occur in the Kinmen island power system where many diesel generators are used. In order to avoid erroneous evaluation of frequency deviation caused by generator tripping, one of the critical issues in system planning is to accurately estimate the maximum frequency deviation during system outage events. The main factors that influence the frequency deviation include the generator inertia (H), damping constant (D), and governor controller parameters. In order to improve the accuracy of the transient stability analysis to obtain more actual frequency deviation, it is critical to have more accurate inertia values of these diesel generators. This paper proposes a useful approach to evaluate reasonable inertia values. With the identified inertia values of diesel generators, the frequency responses of the Kinmen power system obtained from PSS/E simulation are more consistent with the field measurement results. [ABSTRACT FROM AUTHOR]

Short-term load forecast (STLF) plays an important role in power system operations. This paper proposes a spline bases-assisted Recurrent Neural Network (RNN) for STLF with a semi-parametric model being adopted to determine the suitable spline bases for constructing the RNN model. To reduce the exposure to real-time uncertainties, interpolation is achieved by an adapted mean adjustment and exponentially weighted moving average (EWMA) scheme for finer time interval forecast adjustment. To circumvent the effects of forecasted apparent temperature bias, the forecasted temperatures issued by the weather bureau are adjusted using the average of the forecast errors over the preceding 28 days. The proposed RNN model is trained using 15-min interval load data from the Taiwan Power Company (TPC) and has been used by system operators since 2019. Forecast results show that the spline bases-assisted RNN-STLF method accurately predicts the short-term variations in power demand over the studied time period. The proposed real-time short-term load calibration scheme can help accommodate unexpected changes in load patterns and shows great potential for real-time applications. [ABSTRACT FROM AUTHOR]

Considering the effect of peptide insertion on the dipole potential of the lipid membrane, we extend the CAVS coarse-grained (CG) model to the simulation of helical peptides in a membrane environment. In this approach, the CG scheme for a peptide backbone is similar to the treatment in the united-atom model, while we treated the side chain of an amino acid by grouping 1–3 heavy atoms into a CG unit. The CAVS CG force field for peptides is optimized by reproducing the experimental results for the backbone (φ, ψ) distribution and predicting the PMF profiles of transferring organic molecules in a lipid bilayer membrane obtained from all-atom simulations. The CAVS simulation of a helical peptide in a phosphatidylcholine (PC) lipid bilayer revealed that the insertion of a peptide increases the dipole potential of the PC lipid bilayer, in which the peptide and its neutralized ions make a significant contribution. Finally, we carried out the CAVS simulation for five different helical peptides in the PC lipid bilayer to explore the behavior of peptide tilt, showing excellent agreement with the all-atom simulations. Our work suggests that the peptide tilt should relieve the deformation stress from the lipid bilayer, and the peptide aggregation could reduce the peptide tilt by resisting the deformation stress from the surrounding lipids. [ABSTRACT FROM AUTHOR]

Background: Pneumonia is the leading cause of death and hospitalization among young children worldwide, but its risk factors remain unclear.Objective: To evaluate the effect of maternal exposure to diurnal temperature variation (DTV) during preconceptional and prenatal periods on childhood pneumonia.Methods: A retrospective cohort study by case-control design was conducted for pneumonia (N = 699) and normal (N = 811) children under age of 14 who were enrolled in XiangYa Hospital, Changsha, China from May 2017 to April 2019. Demographic data including gender, age, birth season, gestational age, parity, mode of delivery, and parental atopy were collected from the electronic medical records in the hospital system. We obtained the data of daily DTV in Changsha during 2003-2019 from China Meteorological Administration. Maternal exposure to DTV during preconceptional and prenatal periods was respectively calculated by the average of daily DTV during one year and three months before conception and entire pregnancy as well as the three trimesters. The association between maternal exposure to outdoor DTV and childhood pneumonia was analyzed by multiple logic regression model.Results: We found that childhood pneumonia was significantly associated with exposure to an increase in DTV during one year before conception and entire pregnancy, with ORs (95 % CI) = 2.53 (1.56-4.10) and 1.85 (1.24-2.76). We further identified a significant risk of pneumonia of DTV exposure during the first and second trimester of pregnancy. Sensitivity analysis showed that boys were more susceptible to the effect of prenatal exposure to outdoor DTV during pregnancy particularly in the first two trimesters compared to girls.Conclusions: Preconceptional and prenatal exposure to DTV plays an important role in development of childhood pneumonia, especially during the first and second trimesters of pregnancy. [ABSTRACT FROM AUTHOR]

In order to realize the optimal allocation of urban construction and geological environment resources, in this paper, the suitability evaluation index system is established, the comprehensive index method is used to evaluate, and the various evaluation factors are superimposed and analyzed. The results show that the area with good suitability accounts for 44.34%. The area with good suitability accounts for 33.86%. The area with medium suitability accounts for 19.27%, and the area with poor suitability accounts for about 2.49%. In this paper, the comprehensive environmental index method is used to evaluate the geological environment factors affecting the urban construction of Xi'an. The Xi'an urban construction geological environment suitability zoning is obtained. [ABSTRACT FROM AUTHOR]

In order to achieve the goal of mutual coordination between the urban construction and sustainable development of geological and ecological environment, the evaluation method and planning strategy for urban geological and ecological environment quality are proposed. In this study, taking the urban planning of Wansheng Economic Development Zone in Chongqing as an example, the status of geological and ecological environment quality from 2007 to 2019 is analyzed. Twenty evaluation indicators from the five aspects of land, hydrologic, resource, ecologic, and geological environment are selected to construct an evaluation system of urban geological and ecological environment quality. The evaluation indicator system of urban geological and ecological environment quality is established, the weights are determined with the analytic hierarchy process (AHP), and the grading standard of evaluation indicator is given. The urban geological and ecological environment quality is assessed in the way of fuzzy comprehensive evaluation, and the countermeasures for urban and rural planning are proposed. The results show that this system can improve the quality of geological and ecological environment in Wansheng Economic Development Zone in Chongqing; the geological and ecological environment quality of the eco-industrial functional zone 2 (F6) and the eco-industrial functional zone 3 (F7) has been maintained well, while the environment quality of other functional zones has shown a significant downward trend. Finally, the planning suggestions are adapting to the urban geological and ecological environment from three aspects of geological, ecological, and artificial environment. The research in this study provides a good guideline for the overall planning development of the city and rapid assessment of the ecological environment quality. [ABSTRACT FROM AUTHOR]

In order to achieve the goal of mutual coordination between the urban construction and sustainable development of geological and ecological environment, the evaluation method and planning strategy for urban geological and ecological environment quality are proposed. In this study, taking the urban planning of Wansheng Economic Development Zone in Chongqing as an example, the status of geological and ecological environment quality from 2007 to 2019 is analyzed. Twenty evaluation indicators from the five aspects of land, hydrologic, resource, ecologic, and geological environment are selected to construct an evaluation system of urban geological and ecological environment quality. The evaluation indicator system of urban geological and ecological environment quality is established, the weights are determined with the analytic hierarchy process (AHP), and the grading standard of evaluation indicator is given. The urban geological and ecological environment quality is assessed in the way of fuzzy comprehensive evaluation, and the countermeasures for urban and rural planning are proposed. The results show that this system can improve the quality of geological and ecological environment in Wansheng Economic Development Zone in Chongqing; the geological and ecological environment quality of the eco-industrial functional zone 2 (F6) and the eco-industrial functional zone 3 (F7) has been maintained well, while the environment quality of other functional zones has shown a significant downward trend. Finally, the planning suggestions are adapting to the urban geological and ecological environment from three aspects of geological, ecological, and artificial environment. The research in this study provides a good guideline for the overall planning development of the city and rapid assessment of the ecological environment quality. [ABSTRACT FROM AUTHOR]

Due to the higher proportion of non-synchronous power resources in microgrids, adequate frequency regulation supports are required to maintain acceptable system frequency stability. As one of the sources for frequency regulation support in microgrid operation, via proper droop controller operations, wind energy conversion systems (WECS) could deliver kinetic energy stored in their turbines to the grid when needed. However, as the system inertia becomes smaller, the droop controller's response to system disturbances could cause the WECS to resonate with the grid and lead to torsional stress and fatigue damage in the WECS drivetrain. To protect the WECS against such damage, a resonance damper based on pole-zero cancellation technique is proposed in this paper. Simulation results depict the possible resonance phenomenon, and the reduction of undesired fatigue damage by the proposed damper retrofitted to the droop controller while improving the overall frequency regulation. Sensitivity analysis results are also provided to verify its robustness for practical applications. [ABSTRACT FROM AUTHOR]

Due to delays in network reinforcement, many utilities adopt System Integrity Protection Scheme (SIPS) as the short-term last defense to prevent system instability after critical disturbances. One of the challenges in the design of a SIPS is to handle the effects of intermittent renewable generation. Penetration level, geographic distribution, forecast errors, inverters control modes, and synchronous generation displacement are among the sources of effects of renewables that affect the reliable operation of an SIPS. To adapt to variations in system conditions, a new proposition of Adaptable System Integrity Protection Scheme (ASIPS) utilizing offline, online, and edge computing resources is proposed in this article. It aims to maintain reliable operation and reduce control costs under the presence of output variations of renewables. Possible impacts of renewables to the SIPS operations are demonstrated. Based on continuous system state monitoring using Phasor Measurement Units, the proposed response-based ASIPS would trigger optimal controls determined online by using a linearized formulation, or due to time criticality, activate quasi-optimal controls periodically updated and stored in look-up tables using offline computing power. Simulation results demonstrate the effectiveness of the proposed ASIPS in preventing system instability by using reduced control efforts and costs according to real-time operation conditions. [ABSTRACT FROM AUTHOR]

Although mounting evidence has linked environmental factors with childhood allergies, some specific key issues still remain unclear: what is the main environmental factor? what is the critical timing window? And whether these contribute to the development of disease? This selective review summarizes recent epidemiological studies on the association between early-life exposure to indoor/outdoor air pollution and childhood allergic diseases. A literature search was conducted in the PubMed and Web of Science for peer-reviewed articles published until April 2020. Exposure to the traffic-related air pollutant, NO2, exposure during pregnancy and early postnatal periods is found to be associated with childhood allergies, and exposure during different trimesters causes different allergic diseases. However, exposure to classical air pollutants (PM10 and SO2) also contributes to childhood allergy in developing countries. In addition, early-life exposure to indoor renovation and mold/dampness significantly increases the risk of allergy in children. A synergistic effect between indoor and outdoor air pollution is found in the development of allergic diseases. Early-life exposure to outdoor air pollution and indoor environmental factors plays an important role in the development of childhood allergic diseases, and the synergy between indoor and outdoor exposures increases allergy risk. The available findings support the hypothesis of the 'fetal origins of childhood allergy,' with new implications for the effective control and early prevention of childhood allergies. [ABSTRACT FROM AUTHOR]

TiO2/g-C3N4 2D/2D heterojunction nanocomposites were successfully synthesized through a facile self-assembly method. The structure characterization results shows good interaction between TiO2 nanosheets and g-C3N4 nanosheets. The photocatalytic activity of TiO2/g-C3N4 samples were measured by hydrogen production in water splitting under visible light irradiation, which was found that the composites enhance the photocatalytic activity clearly compared to pure g-C3N4 and TiO2 nanosheets. The results could attribute to the formation of 2D heterojunction because of the stimulative charge transfer, promotional separation efficiency of photoexcited electron and hole and the suitable band positions. Besides, the samples exhibited substantial stability under visible light irradiation by the recycling experiments. The feasible photocatalytic mechanism was minutely discussed, which could explain the enhanced photocatalytic activity. [ABSTRACT FROM AUTHOR]

A sustainable power grid involves variable and uncertain generation, load and equipment availability. In order to ensure the frequency quality, power system needs to maintain sufficient reserve capacity to meet the demand and generation variations, and to withstand contingency events. To limit the operation risk to an acceptable level, an operation practice driven and control performance based reserve allocation method is proposed in this paper to determine adequate frequency regulation reserve in an island power system with increasing renewable integrations. Analyses of on-line available frequency regulation reserves and control performance data recorded in Energy Management System are conducted to appraise and manage the risk of non-compliance of frequency control standard. The proposed method is based on the conditional probabilities of reaching certain Control Performance Standard 1 (CPS1) score under the availability of Automatic Generation Control ramping and droop response capability. Comparisons of estimated reserve requirements and expected performance of four dynamic reserve allocation schemes to comply with CPS1 are presented. [ABSTRACT FROM AUTHOR]

Microgrids are designed to ensure reliability and quality of power supply. Reliable islanding transition is key to maintain uninterrupted supply of power to critical loads. Current islanding transition schemes assume fast response from local energy resources to establish secure islanding; however, such fast response systems are often expensive. Analysis of historical events shows that the islanding event, at most instances, can be predicted; by exploiting this feature, this paper proposes an adaptive optimal defense mechanism to establish secure islanding, without acquiring fast response energy resources. The dynamics involved in the islanding transition are incorporated into the search for optimal defense measures by using “simulation optimization” technique. A comparison between no defense approach and with defensive approach for the scenario when the islanding occurs demonstrates the effectiveness of the proposed adaptive defensive approach. The application of the adaptive defensive approach can help improve system performance. Sensitivity analyses are conducted to suggest improvements to reduce the operation cost of proposed defense plan. [ABSTRACT FROM AUTHOR]

The modified asphalt with waste packaging polypropylene (WPP) and WPP/organic rectorite (OREC) was prepared by the melt blending method. The effects of OREC on the physical and aging properties of WPP-modified asphalt were studied. The morphologies, microstructure, and thermal properties of WPP-modified asphalt and WPP/OREC-modified asphalt were characterized by fluorescence microscopy, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogravimetry (TG). The results show that the composite-modified asphalt exhibits excellent ductility and plasticity when the contents of WPP and OREC are 4 wt. % and 1.5 wt. %, respectively. The deformation ability, softening point, ductility, and high-temperature storage stability of WPP-modified asphalt can be improved by adding the appropriate content of OREC. It is demonstrated that the composite-modified asphalt has an outstanding operational performance when the content of OREC is in the range of 1.5–2 wt. %. Compared with base asphalt, the high temperature performance of WPP-modified asphalt and WPP/OREC-modified asphalt is also improved significantly. [ABSTRACT FROM AUTHOR]

We studied dampness and mold in China in relation to rhinitis, ocular, throat and dermal symptoms, headache and fatigue. A questionnaire study was performed in six cities including 36 541 randomized parents of young children. Seven self‐reported signs of dampness were evaluated. Multilevel logistic regression models were used to calculate odds ratios (ORs). Totally, 3.1% had weekly rhinitis, 2.8% eye, 4.1% throat and 4.8% skin symptoms, 3.0% headache and 13.9% fatigue. Overall, 6.3% of the homes had mold, 11.1% damp stains, 35.3% damp bed clothing, 12.8% water damage, 45.4% window pane condensation, 11.1% mold odor, and 37.5% humid air. All dampness signs were associated with symptoms (ORs from 1.2 to 4.6; P < 0.001), including rhinitis (ORs from 1.4 to 3.2; P < 0.001), and ORs increased by number of dampness signs. The strongest associations were for mold odor (ORs from 2.3 to 4.6) and humid air (ORs from 2.8 to 4.8). Associations were stronger among men and stronger in Beijing as compared to south China. In conclusion, dampness and mold are common in Chinese homes and associated with rhinitis and ocular, throat and dermal symptoms, headache and fatigue. Men can be more sensitive to dampness and health effects of dampness can be stronger in northern China. [ABSTRACT FROM AUTHOR]

Multi-order radially polarized modes (RPMs), including Bessel-Gaussian, Gaussian, Super Gaussian, and multi-order hollow Gaussian are respectively utilized as the illumination laser to achieve tip-enhanced spectroscopy (TES). Based on the vector diffraction theory and finite difference time domain (FDTD) analysis, we achieve the optimization of RPM illuminated TES system, including the focal spot size, focal depth, and electric field enhancement factor, in which the focal spot size of 5th order hollow Gaussian RPM is smallest (0.54λ) and the focusing depth of super Gaussian RPM is longest (4.71λ). Specially, it is found that the multi-order hollow Gaussian RPM illuminated TES system with the tip cone angle of 45° reveals better focusing ability and 40~60-fold electric field enhancement factor compared to the linearly polarized mode (LPM) illuminated TES system. These results will supply a useful reference for spectral signal enhancement of TES system. [ABSTRACT FROM AUTHOR]

Operation flexibility is a prerequisite to ensure the success of a power market operation. Due to the variable generation mix, generation units that are flexible to meet the challenge of ramping and provide operation reserve are important in today's system operations. Generators participating in frequency regulation and other ancillary services might lose energy market revenue due to reserved margins, thus regulation performance should be evaluated and paid for. The actual value of operation flexibility is dependent on the system characteristics and the market mechanism. Using the information available in energy management system and combined cycle power plants, this study proposes a simple and practical method to estimate the variant fuel cost increase of combined cycle units to provide frequency regulation service in an island power system. Based on actual operation data, analysis results testify the fact that the efficiency of the combined cycle units is reduced at lower loads and the units are subjected to different fuel cost increases at distinct operation configurations. The proposed method is justifiable and applicable for assessing variant costs incurred in providing energy system flexibility. [ABSTRACT FROM AUTHOR]

Transition to a sustainable energy environment results in aggregated generator and load dynamics in the distribution network. State estimation is a key function in building adequate network models for online monitoring and analyzes. The requirements of distribution system state estimation (DSSE) is becoming stringent because of the needs of new system modeling and operation practices associated with integration of distributed energy resources and the adoption of advanced technologies in distribution network. This paper summarizes the state-of-the-art technology, major hurdles, and challenges in DSSE development. The opportunities, paradigm shift, and future research directions that could facilitate the need of DSSE are discussed. [ABSTRACT FROM PUBLISHER]