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Steroid drug precursors, including C19 and C22 steroids, are crucial to steroid drug synthesis and development. However, C22 steroids are less developed due to the intricacy of the steroid metabolic pathway. In this study, a C22 steroid drug precursor, 9-hydroxy-3-oxo-4,17-pregadiene-20-carboxylic acid methyl ester (9-OH-PDCE), was successfully obtained from Mycolicibacterium neoaurum by 3-ketosteroid-Δ(1)-dehydrogenase and enoyl-CoA hydratase ChsH deficiency. The production of 9-OH-PDCE was improved by the overexpression of 17β-hydroxysteroid dehydrogenase Hsd4A and acyl-CoA dehydrogenase ChsE1-ChsE2 to reduce the accumulation of by-products. The purity of 9-OH-PDCE in fermentation broth was improved from 71.7% to 89.7%. Hence, the molar yield of 9-OH-PDCE was improved from 66.7% to 86.7%, with a yield of 0.78 g/L. Furthermore, enoyl-CoA hydratase ChsH1-ChsH2 was identified to form an indispensable complex in Mycolicibacterium neoaurum DSM 44704. IMPORTANCE C22 steroids are valuable precursors for steroid drug synthesis, but the development of C22 steroids remains unsatisfactory. This study presented a strategy for the one-step bioconversion of phytosterols to a C22 steroid drug precursor, 9-hydroxy-3-oxo-4,17-pregadiene-20-carboxylic acid methyl ester (9-OH-PDCE), by 3-ketosteroid-Δ(1)-dehydrogenase and enoyl-CoA hydratase deficiency with overexpression of 17β-hydroxysteroid dehydrogenase acyl-CoA dehydrogenase in Mycolicibacterium. The function of the enoyl-CoA hydratase ChsH in vivo was revealed. Construction of the novel C22 steroid drug precursor producer provided more potential for steroid drug synthesis, and the characterization of the function of ChsH and the transformation of steroids further revealed the steroid metabolic pathway.

Huanglongbing (HLB) is a global devastating citrus disease that is mainly caused by “Candidatus Liberibacter asiaticus” (CLas). It is mostly transmitted by the insect Asian citrus psyllid (ACP, Diaphorina citri) in a persistent and proliferative manner. CLas traverses multiple barriers to complete an infection cycle and is likely involved in multiple interactions with D. citri. However, the protein–protein interactions between CLas and D. citri are largely unknown. Here, we report on a vitellogenin-like protein (Vg_VWD) in D. citri that interacts with a CLas flagellum (flaA) protein. We found that Vg_VWD was upregulated in CLas-infected D. citri. Silencing of Vg_VWD in D. citri via RNAi silencing significantly increased the CLas titer, suggesting that Vg_VWD plays an important role in the CLas–D. citri interaction. Agrobacterium-mediated transient expression assays indicated that Vg_VWD inhibits BAX- and INF1-triggered necrosis and suppresses the callose deposition induced by flaA in Nicotiana benthamiana. These findings provide new insights into the molecular interaction between CLas and D. citri.

Background 9α-hydroxyandrost-4-ene-3,17-dione (9-OHAD) is a significant intermediate for the synthesis of glucocorticoid drugs. However, in the process of phytosterol biotransformation to manufacture 9-OHAD, product degradation, and by-products restrict 9-OHAD output. In this study, to construct a stable and high-yield 9-OHAD producer, we investigated a combined strategy of blocking Δ1‑dehydrogenation and regulating metabolic flux. Results Five 3-Ketosteroid-Δ1-dehydrogenases (KstD) were identified in Mycobacterium fortuitum ATCC 35855. KstD2 showed the highest catalytic activity on 3-ketosteroids, followed by KstD3, KstD1, KstD4, and KstD5, respectively. In particular, KstD2 had a much higher catalytic activity for C9 hydroxylated steroids than for C9 non-hydroxylated steroids, whereas KstD3 showed the opposite characteristics. The deletion of kstDs indicated that KstD2 and KstD3 were the main causes of 9-OHAD degradation. Compared with the wild type M. fortuitum ATCC 35855, MFΔkstD, the five kstDs deficient strain, realized stable accumulation of 9-OHAD, and its yield increased by 42.57%. The knockout of opccr or the overexpression of hsd4A alone could not reduce the metabolic flux of the C22 pathway, while the overexpression of hsd4A based on the knockout of opccr in MFΔkstD could remarkably reduce the contents of 9,21 ‑dihydroxy‑20‑methyl‑pregna‑4‑en‑3‑one (9-OHHP) by-products. The inactivation of FadE28-29 leads to a large accumulation of incomplete side-chain degradation products. Therefore, hsd4A and fadE28-29 were co-expressed in MFΔkstDΔopccr successfully eliminating the two by-products. Compared with MFΔkstD, the purity of 9-OHAD improved from 80.24 to 90.14%. Ultimately, 9‑OHAD production reached 12.21 g/L (83.74% molar yield) and the productivity of 9-OHAD was 0.0927 g/L/h from 20 g/L phytosterol. Conclusions KstD2 and KstD3 are the main dehydrogenases that lead to 9-OHAD degradation. Hsd4A and Opccr are key enzymes regulating the metabolic flux of the C19- and C22-pathways. Overexpression of fadE28-29 can reduce the accumulation of incomplete degradation products of the side chains. According to the above findings, the MF-FA5020 transformant was successfully constructed to rapidly and stably accumulate 9-OHAD from phytosterols. These results contribute to the understanding of the diversity and complexity of steroid catabolism regulation in actinobacteria and provide a theoretical basis for further optimizing industrial microbial catalysts.

Stricter control of the differential settlement is always required in important buildings more than in ordinary buildings. It becomes a necessity to find a simple and efficient optimum design method for pile foundations in terms of performance and economy. In this paper, an adaptive optimization method (AOM) is proposed to reduce the differential settlement of the pile group and piled raft, in which the piles are located in appropriate locations according to the settlement characteristic of the raft. Piled raft foundations with different types of load and different raft shapes are optimized using this method; soil inhomogeneity and nonlinear characteristic are considered during this process. The optimization results show that the reductions of the differential settlement are more than 80%. The overall foundation performances are improved as the maximum settlements of the foundations are reduced. The maximum bearing capacity of the pile group is no more than its ultimate bearing capacity after optimization design, and part of the excess bearing capacity can be translated into economic savings (AOM-ES). By keeping a good optimization effect of the differential settlement, the number of piles can be reduced by AOM-ES compared with the initial design. The AOM is robust and can be applied to the piled foundations of various raft shapes in layered soils under complex vertical loads with no significant impact on optimization efficiency.

With the rapid development of single-cell RNA sequencing (scRNA-seq) technology, people are able to investigate gene expression at the individual cell level. Identification of cell types via unsupervised clustering is one of the fundamental issues in analyzing single-cell data. However, due to the high dimensionality of expression profiles, traditional clustering methods are difficult to generate satisfactory results. To address this problem, we designed NetworkSSC, a network-guided sparse subspace clustering (SSC) approach. NetworkSSC is based on a similar assumption in SSC that the expression of cells within the same type lies in the same subspace. Moreover, it integrates an additional regularization term to include the gene network’s Laplacian matrix, so as to utilize the network information. The comparison results of 5 scRNA-seq data sets show that NetworkSSC outperforms ordinary SSC and other clustering methods in most cases.

Background 9α-hydroxyandrost-4-ene-3,17-dione (9-OHAD) refers to a significant intermediate for synthesis of glucocorticoid drugs. Microbial transformation of phytosterols to manufacture 9-OHAD has obvious advantages in terms of lead time, cost control, environmental friendliness, etc. However, the product degradation and the formation of by-products restrict their application. In this study, a combined strategy of blocking Δ1‑dehydrogenation and regulating metabolic flow was investigated to construct a stable high-yield 9-OHAD producer. Results Five 3-Ketosteroid-Δ1-dehydrogenase (KstD) were identified in ATCC 35855 and each of them was functionally confirmed by heterologous expression, transcriptional response and knockout analysis. KstD2 showed the highest catalytic activity on 3-ketosteroids, followed by KstD3, KstD1, KstD4 and KstD5. In particular, KstD2 has a much higher catalytic activity for C9 hydroxylated steroids than for C9 non-hydroxylated steroids, whereas KstD3 showed the opposite characteristics. The deletion of kstDs indicated that KstD2 and KstD3 are the main assailants of 9-OHAD degradation. Compared with ATCC 35855, MFΔkstD, the five KstDs deficient train, realized the stable accumulation of 9-OHAD, and its yield increased by 42.57%. The knockout of Opccr or the overexpression of Hsd4A alone could not reduce the metabolic flow of C22 pathway, while the overexpression of Hsd4A based on the knockout of Opccr in MFΔkstD could remarkably reduce the contents of 9-OHHP by-products. The inactivation of FadE28-29 leads to a large amount of accumulation of incomplete side chain degradation products. Therefore, hsd4A and fadE28-29 were co-expressed in MFΔkstDΔopccr successfully eliminated two by-products. Compared with MFΔkstD, the purity of 9-OHAD was improved from 80.24% to 90.14%. Ultimately, 9‑OHAD production reached 12.21 g/L (83.74% molar yield) and the productivity of 9-OHAD was 0.0927 g/L/h. Conclusions Five putative KstDs have been identified and functionally confirmed in ATCC 35855. KstD2 and KstD3 were the main murderers of 9-OHAD degradation. Hsd4A and Opccr are key enzymes regulating the metabolic flux of C19 and C22-pathways. The overexpression of fadE28-29 can reduce the accumulation of incomplete degradation products of side chains. According to the findings above, MF-FA5020 transformant was successfully constructed to rapidly and stably accumulate 9-OHAD from phytosterols. These results contribute to understanding the diversity and complexity of steroid catabolism regulation in actinobacteria and providing a theoretical basis for further optimizing industrial microbial catalyst.

Metal-organic structures are controllably prepared by tuning molecular size, supported substrates, and different kinds of metals. They are characterized by ultra-high vacuum low-temperature scanning tunnelling microscopy and Density functional theory calculations. The relatively larger size of all-trans-retinoic acid (ReA) compared to (2E,4E)-3-methyl-5-(2,6,6-trimethylcyclohex-1-enyl)penta-2,4-dienoic acid (DiA) leads to a bigger gap between neighboring ReA in a tetramer and allows for insertion of molecules, forming high density patterns. ReA forms various structures with different ratios (4:0, 3:1, 2:2) of the two chiral enantiomers on the less reactive Au(111) other than Ag(111). Unlike transition metals, electrostatic attraction between molecules and alkali metals is the origin of the formation of large quartet islands.

Extreme conditions will cause the water level of high fill canal segment to change suddenly, which will affect the velocity and pore pressure of the slope. In this paper, numerical method is used to study the influence of water level sudden change on seepage characteristics of high fill canal segment. HyperMesh software is used to establish the finite element model of typical high fill canal segment under complex foundation conditions. Through the combination of secondary development program and fluid-structure coupling calculation method, the fluid structure cou-pling effect of canal under sudden change of water level is analyzed in ABAQUS. The results show that when the water level changes suddenly, the pore pressure below the free water surface and the velocity near the free surface will be greatly affected.

BackgroundSteroid drugs are particularly important for disease prevention and clinical treatment. However, traditional chemical methods are rarely implemented during the whole synthetic process to generate steroid intermediates due to the intricate steroid structure. Novel steroid drug precursors and their ideal bacterial strains for industrial production have yet to be developed. Among these, 9-OH-4-HP is a potential steroid drug precursor for the synthesis of corticosteroids. In this study, a combined strategy of blocking Δ1-dehydrogenation and the C19 pathway as well as improving the intracellular environment was investigated to construct an effective 9-OH-4-HP-producing strain.ResultsA Δ1-dehydrogenation-deficient strain of wild-type Mycobacterium neoaurum DSM 44074 produces 9-OH-4-HP with a molar yield of 4.8%. hsd4A, encoding a β-hydroxyacyl-CoA dehydrogenase, and fadA5 encoding an acyl-COA thiolase, were separately knocked out to block the C19 pathway in the Δ1-dehydrogenation-deficient strain. The two engineered strains could accumulate 0.59 g L-1 and 0.47 g L-1 9-OH-4-HP from 1 g L-1 phytosterols. Furthermore, hsd4A and fadA5 were knocked out simultaneously in the Δ1-dehydrogenation-deficient strain. The 9-OH-4-HP production from the Hsd4A and FadA5 double-deficient strain was 11.9% higher than that of the Hsd4A -deficient strain and 40.4% higher than that of the strain with FadA5 deficiency, and its selectivity reached 94.9%. Subsequently, the catalase katE from Mycobacterium and an NADH oxidase, nox, from Bacillus subtilis were overexpressed to improve the intracellular environment. Ultimately, 9-OH-4-HP production reached 3.58 g L-1 from 5 g L-1 phytosterols, and the selectivity of 9-OH-4-HP improved to 97%.Conclusionhsd4A and fadA5 are key enzymes in the C19 pathway for phytosterol side chain degradation. Deletion of hsd4A and fadA5 could almost entirely block the C19 pathway. Improving the intracellular environment of Mycobacterium during phytosterol bioconversion could accelerate the conversion process and enhance the productivity of target sterol derivatives.

The self-assembly of l -tryptophan on Cu(111) is investigated by an ultrahigh vacuum scanning tunneling microscope (STM) at 4.4 K. When deposited onto the substrate at around 120 K with a coverage of 0.1 monolayer, molecular trimers, tetramers, hexamers, and chains coexist on Cu(111). Then almost all molecules self-assemble into chiral hexamers after being annealed at room temperature. When increasing molecular coverage to the full layer, a new type of chain is observed on the surface. Based on the high-resolution STM images at sub-molecular level, we suggest that the l -tryptophan molecules are present in neutral, zwitterionic or anionic states in these structures.

Δ1-Dehydrogenation is one of the most important reactions for steroid drug modification. Numerous 3-ketosteroid-Δ1-dehydrogenases (KstDs) catalyzing this reaction were observed in various organisms. However, only a few have been characterized and used for substrate conversion. In this study, a promising enzyme (KstD2) from Mycobacterium neoaurum DSM 1381 was purified and characterized. Interestingly, KstD2 displayed a high activity on a range of substrates, including 17α-hydroxypregn-4-ene-3,20-dione (17α-OH-P); androsta-4,9(11)-diene-3,17-dione (NSC 44826); and 4-androstene-3,17-dione (AD). These reactions were performed under optimal conditions at 40 °C and pH 8.0. Noteworthy, both the activity and stability of the enzyme were sensitive to various metal ions. After optimizing the expression and biocatalyst conditions, up to 1586 U mg-1 intracellular KstD activity on AD could be produced. Furthermore, the associated conversion rate was 99% with 30 g L-1 AD after 8 h. On the other hand, we obtained 99%, 90%, and over 80% of conversion with 20 g L-1 NSC 44826; 10 g L-1 16,17α-epoxyprogesterone; and 20 g L-1 17α-OH-P or canrenone, respectively, after 24 h. Sequence homology and structural analyses indicated that the residue R178 located in a unique short loop among cluster 2 is crucial for substrate recognition which was confirmed by mutagenesis. In summary, this study reports on the first purification and characterization of a KstD from cluster 2. Its remarkable properties deserve more attention to potentially lead to further industrial applications.

Using single molecule as a basic unit of storage devices is an appealing direction of device miniaturization. Tin-phthalocyanine (SnPc) molecules exhibit bistable adsorption configurations, Sn-up and Sn-down. A reversible conversion between these two configurations is readily manipulated and probed by scanning tunneling microscopy (STM). When SnPc molecules are used to form functional devices, they need to adsorb on supporting surfaces. So the growth mechanisms of ultra-thin films on metal surfaces or buffer layers have been investigated. Both layer-island (Stranski–Krastanov) and three-dimensional-island (Volmer–Weber) growth modes are observed in experiments. Because of an electronic decoupling of buffer layers, electronic and vibronic states of SnPc molecules are spectroscopically identified. Molecular switches between Sn-up and Sn-down configurations are achieved by either an electrical mean or mechanical forces. When the STM tip contacts SnPc molecules with controlled structures, electrons transports through single-molecule junctions are explored in detail. In addition, Ag–SnPc–Ag junction exhibits three conductance states at different voltages. These researches pave a way for further development of high-density data storage devices.

A new type of two-dimensional crystal comprising supramolecular pentamers on Au(111) is studied using an ultra-high vacuum low-temperature scanning tunnelling microscope. (2E,4E)-3-Methyl-5-(2,6,6-trimethylcyclohex-1-enyl)penta-2,4-dienoic acid molecules form pentamers through five-fold O⋯H–O hydrogen bonds. In ordered arrays, pentamers interact with each other via van der Waals interactions. The impacts of different annealing temperatures and substrates on the formation of pentamer patterns are systemically investigated.

Fiber-reinforced concrete (FRC) is widely used in the field of civil engineering. However, the research on the damage mechanism of FRC under uniaxial tension is still insufficient, and most of the constitutive relations are macroscopic phenomenological. The aim is to provide a new method for the investigation of mesoscopic damage mechanism of FRC under uniaxial tension. Based on statistical damage theory, the damage constitutive model for FRC under uniaxial tension is established. Two kinds of mesoscopic damage mechanisms, fracture and yield, are considered, which ultimately determines the macroscopic nonlinear stress–strain behavior of concrete. The yield damage mode reflects the potential bearing capacity of materials and plays a key role in the whole process. Evolutionary factor is introduced to reflect the degree of optimization and adjustment of the stressed skeleton in microstructure. The whole deformation-to-failure is divided into uniform damage phase and local failure phase. It is assumed that the two kinds of damage evolution follow the independent triangular probability distributions, which could be represented by four characteristic parameters. The validity of the proposed model is verified by two sets of test data of steel fiber-reinforced concrete. Through the analysis of the variation law of the above parameters, the influence of fiber content on the initiation and propagation of micro-cracks and the damage evolution of concrete could be evaluated. The relations among physical mechanism, mesoscopic damage mechanism, and macroscopic nonlinear mechanical behavior of FRC are discussed.

Ensiling has been widely applied to cope with agricultural solid waste to achieve organic waste valorization and relieve environmental pressure and feedstuff shortage. In this study, co-ensiling of cabbage leaf byproduct and rice straw was performed with inoculation of Lactiplantibacillusplantarum (LP) to investigate the effects of inoculation on ensiling performance and microflora profiles. Compared to the control, LP inoculation preserved more dry matter (DM) content (283.4 versus 270.9 g·kg−1 fresh matter (FM) on day 30), increased lactic acid (LA) content (52.1 versus 35.8 g·kg−1 dry matter on day 15), decreased pH (3.55 versus 3.79 on day 15), and caused accumulation of acetic acid (AA), butyric acid (BA), and ammonia. The investigation showed that LP inoculation modified microflora composition, especially resisting potential pathogens and enriching more lactic acid bacteria (LAB) (p &lt, 0.05). Moreover, Lactiplantibacillus and Lacticaseibacillus were identified as the keystone taxa that influenced physicochemical properties and interactions in microflora. They were also the main functional species that directly restrained undesirable microorganisms (p &lt, 0.05), rather than indirectly working via metabolite inhibition and substrate competition (p &gt, 0.05). The results of this present study improve the understanding of the underlying effect of LP inoculation on improving silage quality and facilitate the bio-transformation of cabbage byproduct and rice straw as animal feed.

In the paper, we report the results for the NLPCC2021 shared-task of Few-shot Learning for Chinese NLP. This shared task is proposed in the context of pre-trained language models, where models only have access to limited human-labeled data. The goal of the task is to compare different learning schemes. The task includes nine sub-tasks and three task forms: single sentence classification, sentence pair classification, and machine reading comprehension. In order to accommodate the properties of few-shot learning, we sampled the examples using various sampling methods, some with 32 examples in total for one dataset, while others with 4 to 16 examples per class. Ninety teams registered for the shared task, employing a wide range of learning schemes, including data augmentation, utilizing multiple templates rather than a single template, using unlabeled data for pre-training or semi-supervised training. The best model achieved 65.3 in the mean accuracy, compared with the human score of 83.9. This result is 8 points higher than our baseline model (using the PET scheme). We believe our few-shot learning tasks and results demonstrate the potential of the recently introduced few-shot learning methods and provide guidance and important empirical evidence for future research.

Composting has been a rational method to dispose of horse or wildlife animal manures, especially in the developed cities with horse clubs and wildlife parks. However, few studies have focused on the mechanism and improvement methods for composting the horse or wildlife animal manures. In this study, we investigated the effect of exogenous compound enzymes on thermophilic composting, which could potentially support the management of horse and wildlife animal manures. With the presence of exogenous enzymes, the duration of high temperature ( 60 °C) was significantly prolonged (p 0.05), and the germination index was significantly improved (p 0.05). More-efficient improvement of composting maturity was associated with the addition of that exogenous enzyme that might influence microflora succession and the interaction among microorganic communities, especially fungal, during the composting process. Furthermore, redundancy and canonical correspondence analyses indicated that the C/N ratio, temperature, and germination index were significant variations to influence bacterial communities (p 0.05). The dominant Flavobacterium, Thermopolyspora, Thermomonospora, and Chaetomium and Saccobolus could play an essential role in carbohydrate and phytotoxin degradation, while Thermobispora and norank_f_Limnochordaceae could lead to temperature rising.

The purpose of this paper is to explore the effect of the baseline control system (BCS) on the fragility of large-scale wind turbine when seismic and wind actions are considered simultaneously. The BCS is used to control the power output by regulating rotor speed and blade-pitch angle in real time. In this study, the fragility analysis was performed and compared between two models using different peak ground acceleration, wind speeds, and specified critical levels. The fragility curves with different wind conditions are obtained using the multiple stripe analysis (MSA) method. The calculation results show that the probability of exceedance specified critical level increases as the wind speed increases in model 1 without considering BCS, while does not have an obvious change in the below-rated wind speed range and has a significant decrease in the above-rated wind speed range in model 2 with considering BCS. The comparison depicts that if the BCS is neglected, the fragility of large-scale wind turbine will be underestimated in around the cut-in wind speed range and overestimated in the over-rated wind speed range. It is concluded that the BCS has a great effect on the fragility especially within the operating conditions when the rated wind speed is exceeded, and it should be considered when estimating the fragility of wind turbine subjected to the interaction of seismic and aerodynamic loads.

We study the convex relaxation of a polynomial optimization problem, maximizing a product of linear forms over the complex sphere. We show that this convex program is also a relaxation of the permanent of Hermitian positive semidefinite (HPSD) matrices. By analyzing a constructive randomized rounding algorithm, we obtain an improved multiplicative approximation factor to the permanent of HPSD matrices, as well as computationally efficient certificates for this approximation. We also propose an analog of van der Waerden's conjecture for HPSD matrices, where the polynomial optimization problem is interpreted as a relaxation of the permanent., Comment: 12 pages, 2 figures

Handwriting verification represents an important area in forensic science. Herein, handwritings based on different types and brands pen ink samples made in China were investigated by non-invasive micro-identification methods. Scanning electron microscopy and energy spectrum (SEM-ES) were employed to measure the micro elements and component analysis of the written traces, and spectral mapping (surface scanning) function was focused. The exact assessments of elements in handwriting traces can distinguish the microcosmic differences between different types and brands ink in handwriting, which provides a new means of analysis and research methods of pen handwriting detection in forensic science.

In order to investigate the effect of a baseline control system (BCS) on dynamic and fatigue characteristics of modern wind turbines, the simulation results of a 5-MW wind turbine subjected to wind loading without and with considering BCS (No. 1 and No. 2, respectively) were compared. The displacement and moment of tower and blades were compared, and the rainflow counting algorithm was used to analyze the fatigue load expressed in damage equivalent load (DEL). The results indicate that the mean and maximum values of structural dynamic responses in No. 2 have a great reduction with wind speed exceeding the rated speed comparing to No. 1; the 3P (3-times the frequency of rotor speed) of the wind turbine rotor speed will be close to the tower fore-aft (FA) natural frequency with the wind velocity around the cut-in speed in No. 2, which caused larger dynamic responses, number of load cycles, and DELs for the tower compared with No. 1; when wind velocity exceeds the rated wind speed, the BCS caused higher fluctuation of loads, increasing the related DELs. It is concluded that when analyzing the dynamic responses and designing wind turbine tower and blades, taking the BCS into account during analysis is significant.

In this paper, the influence of the number of ground motions on fragility analysis of 5 MW wind turbines under the excitation of aerodynamic and seismic loads is investigated to acquire the sufficient number of records for reasonable fragility estimation. Two scenarios, parked and normal operation, were simulated with the number of actual recorded ground motions ranging from 2 to 48. The fragility function parameters are estimated by utilizing the method of multiple stripe analysis (MSA), and the relationship between the number of ground motions and estimated parameters for each scenario is discussed. In addition, the influence of the number of ground motions on the range of estimated parameters with a 95% confidence interval is also discussed. The simulation results show that there are significant differences between the two scenarios in terms of fragility analysis for 5 MW wind turbines with the interaction of wind and seismic loads, and the lesser number of earthquakes is needed for a normal operation scenario compared to the parked scenario when obtaining the same accuracy fragility estimation. Furthermore, the appropriate number of ground motions to accurately estimate the fragility parameters of 5 MW wind turbines for the two scenarios is presented herein, which is almost unaffected by different wind spectra.

Mobility-as-a-Service (MaaS) systems, such as ride-sharing services, have expanded very quickly over the past years. However, the popularity of MaaS systems make them increasingly vulnerable to denial-of-service (DOS) attacks, in which attackers attempt to disrupt the system to make it unavailable to the customers. Expanding on an established queuing-theoretical model for MaaS systems, attacks are modeled as a malicious control of a fraction of vehicles in the network. We then formulate a stochastic control problem that maximizes the passenger loss in the network in steady state, and solve it as a sequence of linear and quadratic programs. Combined with a Jackson network simulation and an economic model of supply and demand for attacks, we quantify how raising the cost of attacks (via cancellation fees and higher level of security) removes economical incentives for DoS attacks. Calibrating the model on 1B taxi rides, we dynamically simulate a system under attack and estimate the passenger loss under different scenarios, such as arbitrarily depleting taxis or maximizing the passenger loss. Cost of attacks of U.S.$ 15 protects the MaaS system against DoS attacks. The contributions are thus a theoretical framework for the analysis of the network, and practical conclusions in terms of financial countermeasures to the attacks.

The objective of this paper is to research the fragility of large-scale wind turbines considering the combination of seismic and aerodynamic loads. According to the International Electrotechnical Commission (IEC) 61400-1 and pushover analysis, the critical moment and displacement for wind turbines were proposed. The moment based and displacement based fragility curves under different wind speeds were obtained by using multiple stripe analysis (MSA) approach and compared between the first scenario of normal operation condition with the baseline control system (BCS) working and the second scenario of parked condition. The simulation results indicate that the effect of aerodynamic damping on structural response of a wind turbine during normal operation results in a reduction in the maximum values of dynamic response compared to the parked condition, which causes that the probability of exceeding limit state in the first scenario is less than that in the second scenario. It illustrates that, a wind turbine subjected to the combination of seismic and aerodynamic loads in normal operation condition is safer than in parked condition. Finally, it can be concluded that the fragility of large scale wind turbines can be reduced by keeping the BCS working when earthquake happens.

Vehicle detection is the key component of driver assistance system based on computer vision. It is the basis for speed measurement, ranging and anti-collision. As an important part, it received wide attention and was developed rapidly in recent years. The complexity of the background environment and the real-time change brings great difficulty to vehicle detection. In this paper, a monocular camera is installed in front of the vehicle to collect images, and the digital image processing technology combined with machine learning is used for the vehicle detection. This process can be divided into two stages: the rapid positioning of the target and the target recognition. The experiments show that vehicles can be detected in the image quickly and effectively by this algorithm.

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In order to study the effect of surface structure on absorption properties of microwave absorbing materials. Methods Four models of microwave absorbing materials with blackbody structure are established using 3D modeling software. Then, microwave absorbing inkjet ink was prepared, and microwave absorbing materials with blackbody structure are prepared using 3D printer. The microwave absorbing properties of different materials in 6–40 GHz are tested according to GJB2038A-2011 for square flat materials: 180 mm × 180 mm × 4 mm. Results the maximum reflection loss of solid plates is only −1.45 dB. The maximum reflection loss of conical cavity is −1.48 dB, the maximum reflection loss of inverted cone cavity is −2.78 dB, the maximum reflection loss of swallow tail cavity is −3.84 dB, the absorption performances of these models are greatly improved at more than 30 GHz. The maximum reflection loss of fishtail cavity is up to −5.92 dB, which have the better absorption performances at more than 20 GHz. Conclusion The opening diameter of blackbody cavity in microwave absorbing material is 2.5 mm, when the 1/8 of the incident electromagnetic wave length is less than 2.5 mm (the electromagnetic wave frequency is greater than 15 GHz), the waveguide effect will be obvious. At this time, the wave impedance of the material decreases, the electromagnetic wave entering the material increases, which is finally absorbed in the blackbody cavity after being reflected many times. Through the design of the blackbody cavity structure, increasing the reflection times of the electromagnetic wave in the blackbody can improve the absorption intensity and the absorption bandwidth of the material.

The fermentation of leaf vegetable waste to produce animal feed reduces the environmental impact of vegetable production and transforms leaf vegetable waste into a commodity. We investigated the effect of exogenous probiotics and lignocellulose enzymes on the quality and microbial community of fermented feed (FF) produced from cabbage waste. The addition of exogenous probiotics resulted in increased crude protein (CP) content (p &lt, 0.05), better odor (moderate organic acid and ethanol, with low ammonia-N, p &lt, 0.05), and a lower relative abundance (RA) of pathogens (below 0.4%, p &lt, 0.05) in FF, compared to without. With the addition of exogenous probiotics, only Pediococcus and Saccharomyces were enriched and symbiotic in FF, these were the keystone taxa to reduce the abundance of aerobic, form-biofilms, and pathogenic microorganisms, resulting in an efficient anaerobic fermentation system characterized by facultative anaerobic and Gram-positive bacterial communities, and undefined saprotroph fungal communities. Thus, inoculation of vegetable waste fermentation with exogenous probiotics is a promising strategy to enhance the biotransformation of vegetable waste into animal feed.

The conventional linear quadratic regulator (LQR) control algorithm is one of the most popular active control algorithms. One important issue for LQR control algorithm is the reduction of structure’s degrees of freedom (DOF). In this work, an LQR control algorithm with superelement model is intended to solve this issue leading to the fact that LQR control algorithm can be used in large finite element (FE) model for structure. In proposed model, the Craig-Bampton (C-B) method, which is one of the component mode syntheses (CMS), is used to establish superelement modeling to reduce structure’s DOF and applied to LQR control algorithm to calculate Kalman gain matrix and obtain control forces. And then, the control forces are applied to original structure to simulate the responses of structure by vibration control. And some examples are given. The results show the computational efficiency of proposed model using synthesized models is higher than that of the classical method of LQR control when the DOF of structure is large. And the accuracy of proposed model is well. Meanwhile, the results show that the proposed control has more effects of vibration absorption on the ground structures than underground structures.

In this paper, uniaxial compression tests were carried out for recycled aggregate concrete with water cement ratios of 0.38, 0.49, and 0.66 and replacement ratios of 0%, 25%, 50%, 75%, and 100%, respectively. The influence of the replacement ratio of recycled aggregate and water cement ratio on the strength, elastic modulus, and deformation characteristics of concrete was discussed. The results show that the replacement rate of recycled aggregate has a significant effect on the macro stress&ndash, strain behavior of concrete. In the case of a constant water cement ratio, the peak nominal stress first decreases and then increases with the increase of the replacement rate, while the water cement ratios equal 0.38, 0.49, and 0.66, the corresponding transition states are 25%, 50%, and 50% of the replacement rate, respectively. The deformation and failure is characterized by two stages: distributed damage and local failure. Combined with the statistical damage mechanics, the influence of the aggregate replacement rate on the damage evolution mechanism of recycled concrete on a mesoscopic scale was explored. Two mesoscopic damage modes, fracture and yield, are considered. Their cumulative evolutions are assumed to follow triangular probability distributions, which could be characterized by four parameters. The peak nominal stress state and the critical state are distinguished, and the latter is defined as a precursor to local failure. With the increase of the replacement rate of recycled aggregate, the inhomogeneous evolution of mesoscopic damage shows obvious regular change, which is consistent with the internal chemical and physical mechanism and macro nonlinear stress&ndash, strain behavior.

In this paper, a new semi-active fuzzy control strategy is proposed for controlling edgewise vibrations of wind turbine blades under extreme wind. The control forces are provided by magnetorheological (MR) dampers mounted inside blades and appropriately manipulated according to a prescribed fuzzy control law. The fuzzy control system produces the required voltage to be input to the damper so that a desirable damper force can be produced. The finite element model of wind turbine with MR dampers is formulated, which considers the blade-tower coupling. Aerodynamic loads corresponding to a combination of steady wind and the effect of turbulence are computed by applying the blade element momentum (BEM) theory. Furthermore, the influence of position and number of the controllers is taken into account. The results of numerical simulations show that the proposed semi-active fuzzy control system can be beneficial in reducing the vibrations of wind turbine blades under extreme wind.

The self-assembly behavior of a V-shaped bispyridine, 1,3-bi(4-pyridyl)benzene (BPyB), was studied by scanning tunneling microscopy on the (111) surfaces of Cu, Ag, and Au. BPyB molecules coordinately bonded with active Cu adatoms on Cu(111) in the form of complete polygonal rings at low coverages. On Ag(111), BPyB molecules aggregated into two-dimensional islands by relatively weak intermolecular hydrogen bonds. The coexistence of hydrogen bonds and coordination interaction was observed on the BPyB-covered Au(111) substrate. Density functional theory calculations of the metal-molecule binding energy and Monte Carlo simulations were performed to help understand the forming mechanism of molecular superstructures on the surfaces. In particular, the comprehensive orbital composition analysis interprets the observed metal-organic complexes and reveals the importance of relativistic effects for the extraordinary activity of gold adatoms. The relativistic effects cause the energy stability of the Au 6s atomic orbital and decrease the energy separation between the Au 6s and 5d orbitals. The enhanced sd hybridization strengthens the N-Au-N bond in BPyB-Au-BPyB complexes.

Kinetically controlled hierarchical self-assemblies of all-trans-retinoic acid on Au(111) were investigated via low-temperature scanning tunneling microscopy in ultra-high vacuum. The dominant molecular hierarchical superstructure could be selectively controlled to dimer, tetramer, or pentamer patterns, which were stabilized by hydrogen bonds and van der Waals interactions.

Safety and integrity of NPP must be ensured during the plant life in any design conditions, particularly, in the event of a severe earthquake. Base isolation as a popular and powerful technology can drastically reduce the seismic response of the structure and prevent the structure from damage. The objective of this paper is to numerically investigate the dynamic response of the AP1000 Nuclear Island (NI) building with and without isolators under a typical safe shutdown earthquake (SSE). By the help of a sophisticated detailed three-dimensional finite element model of the Nuclear Island, the different design solutions are compared in terms of acceleration and relative displacement. The decreasing amplitude ratio (DAR) obtained in the calculations highlights the effectiveness of the isolation system in mitigating the seismic response of the nuclear island of AP1000. Acceleration floor response spectra (carried out from both isolated and non-isolated seismic analysis) are herein also presented and compared in order to validate the isolation technology effectiveness. The obtained numerical results highlight the drastic reduction of considered floor accelerations as the base isolation major effect. The connection of pipelines and design criteria of isolators presently recommended for the stability of isolated building are also validated and verified to highlight the feasibility and safety of the base isolation system. In addition, seismic gap, expansion joint and horizontal fail safe system are also recommended to apply in the isolated structure.

A new elasto-plastic constitutive model for jointed rock mass, which can consider the persistence ratio in different visual angle and anisotropic increase of plastic strain, is proposed. The proposed the yield strength criterion, which is anisotropic, is not only related to friction angle and cohesion of jointed rock masses at the visual angle but also related to the intersection angle between the visual angle and the directions of the principal stresses. Some numerical examples are given to analyze and verify the proposed constitutive model. The results show the proposed constitutive model has high precision to calculate displacement, stress and plastic strain and can be applied in engineering analysis.