Grey wolf optimizer (GWO) is a new meta-heuristic algorithm. The GWO algorithm mimics the leadership hierarchy and hunting mechanism of grey wolves in nature. Three main stages of hunting include: ...encircling, tracking and attacking. It is easy to fall into local optimum when used to optimize high-dimensional data, and there is imbalance between exploration and exploitation. An improved grey wolf optimizer based on tracking mode and seeking mode is proposed to improve the diversity of the population and the ability of the algorithm to balance exploration and exploitation. The algorithm is verified by simulation experiments in three parts. Firstly, the proposed grey wolf optimizer based on tracking mode (TGWO), the improved grey wolf optimizer based on seeking mode (SGWO), the improved grey wolf optimizer based on tracking and seeking mode (TSGWO), Grey Wolf Optimizer (GWO), Particle Swarm Optimization (PSO), Salp Swarm Algorithm (SSA), Sine Cosine Algorithm (SCA), Ant Lion Optimizer (ALO), Whale Optimization Algorithm (WOA) and Moth-flame Optimization (MFO) are adopted to optimize 21 typical benchmark functions respectively, and the obtained statistical simulation results are compared; Secondly, the improved algorithm proposed in this paper is compared with Binary Grey Wolf Optimizer (BGWO), Hybrid PSOGWO Optimization (PSOGWO) and GWO Algorithm Integrated with Cuckoo Search (GWOCS); Finally, it is applied to the lightest design engineering problem of pressure vessels. Simulation results show that the superior performance of the proposed algorithm for exploiting the optimum and it has advantages in terms of exploration. The improved grey wolf optimizer based on tracking mode and seeking mode can better solve function optimization and classical engineering problems with constraints. It was found the improved grey wolf optimizer based on tracking mode has the high precision and the characteristics of balanced exploration and exploitation.
To characterize aerosol pollution in Beijing, size-resolved aerosols were collected by MOUDIs during CAREBEIJING-2006 field campaign at Peking University (urban site) and Yufa (upwind rural site). ...Fine particle concentrations (PM1.8 by MOUDI) were 99.8±77.4 μg/m3 and 78.2±58.4 μg/m3, with PM1.8/PM10 ratios of 0.64±0.08 and 0.76±0.08 at PKU and Yufa, respectively, and secondary compounds accounted for more than 50% in fine particles. PMF model analysis was used to resolve the particle modes. Three modes were resolved at Yufa, representing condensation, droplet and coarse mode. However, one more droplet mode with bigger size was resolved, which was considered probably from regional transport. Condensation mode accounted for 10%–60% of the total mass at both sites, indicating that the gas-to-particle condensation process was important in summer. The formation of sulfate was mainly attributed to in-cloud or aerosol droplet process (PKU 80%, Yufa 70%) and gas condensation process (PKU 14%, Yufa 22%). According to the thermodynamic instability of NH4NO3, size distributions of nitrate were classified as three categories by RH. The existence of Ca(NO3)2 in droplet mode indicated the reaction of HNO3 with crustal particles was also important in fine particles. A rough estimation was given that 69% of the PM10 and 87% of the PM1.8 in Beijing urban were regional contributions. Sulfate, ammonium and oxalate were formed regionally, with the regional contributions of 90%, 87% and 95% to PM1.8. Nitrate formation was local dominant. In summary regional secondary formation led to aerosol pollution in the summer of Beijing.
Aims
Under intensive and stressful aquaculture conditions, cultured eels are highly susceptible to virulent Aeromonas sp. infections. To rapidly and simultaneously confirm Aeromonas isolate and its ...virulence, a two‐tube multiplex PCR (mPCR) assay incorporating gyrB gene for genus‐specific recognition and seven major virulence genes for virulence assessment was developed.
Methods and Results
Eight pairs of primers were designed and divided into two groups—gyrB, ahpA, epr and aerA in tube 1 and alt, act, ast and hlyA in tube 2. The optimized mPCR conditions were the same except for their final concentrations. The specificity of the mPCR was validated by the extracted DNA of 10 Aeromonas and 8 non‐Aeromonas species, or mixed DNA templates. Detection limits were determined to be 200 copies per μl in tube 1 and 20 copies per μl in tube 2. The mPCR reproducibility was tested by both artificial challenge and clinical samples.
Conclusions
The results showed this two‐tube mPCR assay was rapid, specific, sensitive and reliable.
Significance and Impact of the Study
To our knowledge, this is the first report to distinguish virulent Aeromonas isolates from nonvirulent ones by seven popular and major virulence genes at the genus‐specific level. And it will be useful for large‐scale screening of virulent Aeromonas sp. in cultured eels.
Calcium-based thermochemical energy storage (TCES) provides a realizable solution to address the challenges of intermittence and volatility in the large-scale utilization of clean energy. Although ...modified CaCO
3
/CaO systems have shown promise for stable cyclic performances, the modification mechanism of different additives remains unclear, and a unified theoretical framework for selecting modified elements is needed. This work systematically explores the effects of 34 metal elements on the cyclic stability, heat release capacity, and thermal conductivity of a CaCO
3
/CaO TCES material using density functional theory (DFT) calculations and experimental tests. The surface energy of the modified CaO surfaces is proportional to the atomic radius for non-transition metal atoms or the ionization energy for transition metal atoms. Trends in Ca
4
O
4
adsorption energy are generally opposite to those of surface energy. Both low surface energy and high Ca
4
O
4
adsorption energy indicate surface stability. Furthermore, the heat release capacity of the modified CaO surfaces is investigated by studying the CO
2
adsorption process. Al, Zr, and Ce modifications enhance the stability and affinity for CO
2
of the surfaces, but competition with the original CaO for CO
2
adsorption may reduce heat release. Additionally, phonon calculations indicate metal substitution can hinder heat transfer by strengthening the coupling between optical and acoustic branches. Finally, the microstructure, cyclic stability, heat release capacity, and thermal conductivity are studied by experiments, and the reliability of the computational predictions is verified. This work uncovers the modification rules of different metal elements on the TCES performances of CaCO
3
/CaO pairs at the atomic scale. The findings provide a theoretical reference for material modification, and can serve as a basis for higher-scale study to offer more reliable guidance for material modification and facilitate future applications.
This work establishes a structure-performance relationship between the atomic parameters of metals and the performance of modified calcium-based TCES materials.
This case series reviews previous publications and reports four feline spinal epidural empyema cases that presented with non‐ambulatory thoracolumbar myelopathy. Two cats underwent myelography and ...two MRI. Bacteria were obtained in three cases, in two from epidural abscesses and from a tail base wound in one; histopathological examination of epidural tissue showed pyogranulomatous changes in the remaining cat. Three cats were treated by surgical decompression plus antimicrobial therapy and one cat was treated medically. All cats showed satisfactory improvement following treatment over a follow‐up period of 3 months. Spinal epidural empyema is a rare condition but all cats in this series had favourable outcomes.
Past studies have shown that amplified insulin-like growth factor 1 (IGF1)/IGF1 receptor (IGF1-R) signalling has an important role in colorectal cancer (CRC) development, progression and resistance ...to treatment. In this report, we demonstrate that downregulation of microRNA-497 (miR-497) as a result of DNA copy number reduction is involved in upregulation of IGF1-R in CRC cells. MiR-497 and miR-195 of the miR-15/16/195/424/497 family that share the same 3' untranslated region (3'UTR) binding seed sequence and are predicted to target IGF1-R were concurrently downregulated in the majority of CRC tissues relative to paired adjacent normal mucosa. However, only overexpression of miR-497 led to suppression of the IGF1-R 3'UTR activity and downregulation of the endogenous IGF1-R protein in CRC cells. This was associated with inhibition of cell survival, proliferation and invasion, and increased sensitivity to apoptosis induced by various stimuli including the chemotherapeutic drugs cisplatin and 5-fluorouracil, and the death ligand tumour necrosis factor-related apoptosis-inducing ligand. The biological effect of miR-497 on CRC cells was largely mediated by inhibition of phosphatidylinositol 3-kinase/Akt signalling, as overexpression of an active form of Akt reversed its impact on cell survival and proliferation, recapitulating the effect of overexpression of IGF1-R. Downregulation of miR-497 and miR-195 appeared to associate with copy number loss of a segment of chromosome 17p13.1, where these miRs are located at proximity. Similarly to miR-195, the members of the same miR family, miR-424 that was upregulated, and miR-15a, miR-15b and miR-16 that were unaltered in expression in CRC tissues compared with paired adjacent normal mucosa, did not appear to have a role in regulating the expression of IGF1-R. Taken together, these results identify downregulation of miR-497 as an important mechanism of upregulation of IGF1-R in CRC cells that contributes to malignancy of CRC.
In Gram-negative bacteria, outer-membrane integrity is essential for survival and is monitored by the σ Ε stress-response system, which initiates damage-repair pathways. One activating signal is ...unassembled outer-membrane proteins. Using biochemical and genetic experiments in Escherichia cotí, we found that off-pathway intermediates in lipopolysaccharide transport and assembly provided an additional required signal. These distinct signals, arising from disruptions in the transport and assembly of the major outer-membrane components, jointly determined the rate of proteolytic destruction of a negative regulator of the σ Ε transcription factor, thereby modulating the expression of stress-response genes. This dual-signal system permits a rapid response to dysfunction in outer-membrane biogenesis, while buffering responses to transient fluctuations in individual components, and may represent a broad strategy for bacteria to monitor their interface with the environment.
Using alloy design, an Fe
77Mo
5P
9C
7.5B
1.5 bulk metallic glass matrix composite reinforced by in situ formed ductile α-Fe dendrites has been developed. In contrast to the monolithic Fe-based bulk ...metallic glasses that usually fail in brittle fracture, the resulting composite shows a significant plastic strain of more than 30% as well as a high fracture strength of over 3.0
GPa. The in situ formation of the ductile α-Fe dendrites accounts for the significant enhancement of the plasticity.
Nitro-aromatic compounds (NACs), as important contributors to the light absorption by brown carbon, have been widely observed in various ambient atmospheres; however, their formation in the urban ...atmosphere was little studied. In this work, we report an intensive field study of NACs in summer 2016 at an urban Beijing site, characterized by both high-NOx and anthropogenic VOC dominated conditions. We investigated the factors that influence NAC formation (e.g., NO2, VOC precursors, RH and photolysis) through quantification of eight NACs, along with major components in fine particulate matter, selected volatile organic compounds, and gases. The average total concentration of the quantified NACs was 6.63 ng m-3, higher than those reported in other summertime studies (0.14–6.44 ng m-3). 4-Nitrophenol (4NP, 32.4 %) and 4-nitrocatechol (4NC, 28.5 %) were the top two most abundant NACs, followed by methyl-nitrocatechol (MNC), methyl-nitrophenol (MNP), and dimethyl-nitrophenol (DMNP). The oxidation of toluene and benzene in the presence of NOx was found to be a more dominant source of NACs than primary biomass burning emissions. The NO2 concentration level was found to be an important factor influencing the secondary formation of NACs. A transition from low- to high-NOx regimes coincided with a shift from organic- to inorganic-dominated oxidation products. The transition thresholds were NO2∼20 ppb for daytime andNO2∼25 ppb for nighttime conditions. Under low-NOx conditions, NACs increased with NO2, while the NO3- concentrations and (NO3-)/NACs ratios were lower, implying organic-dominated products. Under high-NOx conditions, NAC concentrations did not further increase with NO2, while theNO3- concentrations and (NO3-)/NACs ratios showed increasing trends, signaling a shift from organic- to inorganic-dominated products. Nighttime enhancements were observed for 3M4NC and 4M5NC, while daytime enhancements were noted for 4NP, 2M4NP, and DMNP, indicating different formation pathways for these two groups of NACs. Our analysis suggested that the aqueous-phase oxidation was likely the major formation pathway of 4M5NC and 3M5NC, while photo-oxidation of toluene and benzene in the presence of NO2 could be more important for the formation of nitrophenol and its derivatives. Using the (3M4NC+4M5NC) / 4NP ratios as an indicator of the relative contribution of aqueous-phase and gas-phase oxidation pathways to NAC formation, we observed that the relative contribution of aqueous-phase pathways increased at elevated ambient RH and remained constant at RH > 30 %. We also found that the concentrations of VOC precursors (e.g., toluene and benzene) and aerosol surface area acted as important factors in promoting NAC formation, and photolysis as an important loss pathway for nitrophenols.
In this paper, a novel nonconventional angle displacement (i.e., 15°) between two sets of three-phase windings is proposed for dual three-phase permanent-magnet (PM) machines. First, all feasible ...angle displacements between the two three-phase winding sets for various slot/pole number combinations of dual three-phase machines are discussed in general. Then, an in-depth investigation is carried out on a 24-slot/10-pole dual three-phase PM machine as an example covering various electromagnetic performances. The investigation shows that under healthy and three-phase open-circuit conditions, the proposed 15° configuration has a comparable electromagnetic performance to the 30° configuration, and a better performance than the 0° counterpart. Furthermore, under three-phase short-circuit (SC) condition, the proposed 15° configuration has the lowest SC current, smallest braking torque, and the best PM demagnetization withstand capability. Finally, three prototype 24-slot/10-pole surface-mounted PM machines are built and tested to verify the theoretical analyses.
PDF
