ARTICLE | doi:10.20944/preprints202304.1005.v1
Subject: Physical Sciences, Optics And Photonics Keywords: acoustic relaxation absorption; gas relaxation acoustics; ultrasonic sensor; DBR fiber laser; carbon dioxide detection
Online: 27 April 2023 (02:32:13 CEST)
Reconstruction of acoustic relaxation absorption curve is a powerful approach to ultrasonic gas sensing, but requires known of a series ultrasonic absorption at various frequencies around effective relaxation frequency. Ultrasonic transducer is a most widely deployed sensor for ultrasonic wave propagation measurement and works only at a fixed frequency or specific environment like water, so a large number of ultrasonic transducers operating at various frequencies are required to recover an acoustic absorption curve with a relative large bandwidth, which cannot suit for large-scale practical applications. This paper proposes a wideband ultrasonic sensor using a distributed Bragg reflector (DBR) fiber laser for gas concentration detection through acoustic relaxation absorption curve reconstruction. With a relative wide and flat frequency response, the DBR fiber laser sensor measures and restores a full acoustic relaxation absorption spectrum of CO2 using a decompression gas chamber between 0.1 and 1 atm to accommodate the main molecular relaxation processes, and interrogates with a non-equilibrium Mach-Zehnder (M-Z) interferometer to gain a sound pressure sensitivity of -45.4 dB. The measurement error of the acoustic relaxation absorption spectrum is less than 1.32%.
ARTICLE | doi:10.20944/preprints202212.0481.v1
Subject: Computer Science And Mathematics, Artificial Intelligence And Machine Learning Keywords: Meta-heuristic algorithm; Jellyfish search algorithm; Sine and cosine learning factors; Local escape operator; Opposition-based learning
Online: 26 December 2022 (09:06:46 CET)
Jellyfish search (JS) algorithm impersonates the foraging behavior of jellyfish in the ocean. It is a new developed meta-heuristic algorithm that solves complex and real world optimization problems. The global explore capability and robustness of JS are strong, but JS still has great development space in solving complex optimization problems with high dimensions and multiple local optima. Therefore, an enhanced jellyfish search (EJS) algorithm is developed in this study, and three improvements are made: (i) By adding sine and cosine learning factors, the jellyfish can learn from both random individual and best individual during Type B motion in swarm to enhance the optimization capability and convergence speed; (ii) Adding local escape operator can skip local optimal trap and boost the exploitation ability of JS; (iii) Opposition-based learning operator and quasi-opposition learning operator can increase and strengthen the population distribution more diversified, and better individuals are selected from present and new opposition-solution to participates in the next iteration, which can boost the solution’s quality, meanwhile convergence speed is fasted and its precision is increased. In addition, the performance contrast of the developed EJS and some previous outstanding and advanced methods are evaluated on CEC2017, CEC2019 test suite and six real engineering example of case. It is demonstrated that EJS algorithm escaped the trap of local optimum, enhanced the solution’s quality and the calculation speed. What’s more, the practical engineering applications of EJS algorithm also verify its superiority and effectiveness in solving both constrained and unconstrained optimization problems, and it stretched one’s mind for solving such optimization problems.
ARTICLE | doi:10.20944/preprints202306.2176.v1
Subject: Computer Science And Mathematics, Computer Vision And Graphics Keywords: Intelligent information perception; point cloud registration; vehicle mounted MEMS LiDAR; SSM-NDT algorithm; self-adaptive segmentation model; autonomous vehicle
Online: 30 June 2023 (07:28:03 CEST)
Abstract: The Micro-Electro-Mechanical System (MEMS) LiDAR point cloud in autonomous vehicles has a large deflection range, which results in slow registration speed and poor applicability. To maximize speed, an improved NDT (Normal Distribution Transform) method that integrates point cloud density features has been proposed. First, the point cloud is reduced using a modified voxel filter and a pass-through filter. Next, the ISS (Intrinsic Shape Signature) algorithm is utilized to analyze the point cloud features and extract keypoints, the 4PCS (4-Point Congruent Sets) algorithm is then employed to calculate the initial pose under the constraints of the keypoint set to complete the coarse registration. Finally, the self-adaptive segmentation model is constructed by using KD-tree to obtain the density features of keypoints, and the NDT algorithm is combined with this model to form an SSM-NDT algorithm, which is used for fine registration. Each algorithm was compared on the autonomous vehicle dataset PandaSet and actual collected data sets, the results show that the novel method increases the speed by at least 60% and takes into account good registration accuracy and strong anti-interference.
REVIEW | doi:10.20944/preprints202212.0272.v2
Subject: Biology And Life Sciences, Life Sciences Keywords: Apiaceae plants; traditional use; phytochemistry; bolting and flowering; controlling approaches
Online: 5 May 2023 (05:47:46 CEST)
Apiaceae plants have been widely used as traditional Chinese medicines (TCMs) for the treatment of removing dampness, relieving superficies, and dispelling cold, etc. In order to exploit the potential application and improve the yield and quality of Apiaceae medicinal plants (AMPs), The traditional use, phytochemistry, modern pharmacological use, effect of bolting and flowering (BF), and approaches for controlling the BF were summarized. Currently, about 228 AMPs have been recorded as TCMs with 6 medicinal parts, 72 traditional uses, 62 modern pharmacological uses, and 5 main kinds of metabolites. Three effect degrees (i.e., significantly affected, affected to some extent, and no significantly affected) could be classed based on the yield and quality. The BF of individual plants (e.g., Angelica sinensis) could be effectively controlled by the standard cultivation techniques, while the mechanism of BF has not been systemically revealed. This review will provide useful references for the reasonable exploration and high-quality production of AMPs.
ARTICLE | doi:10.20944/preprints201911.0129.v1
Subject: Business, Economics And Management, Economics Keywords: global emission reduction; trade; FDI; BRICS countries; Bootstrap ARDL
Online: 12 November 2019 (15:50:57 CET)
We used the Bootstrap ARDL method to test the relationship between the export trades, FDI and CO2 emissions of the BRICS countries. We found that China's foreign direct investment and the lag one period of CO2 emissions have a cointegration on exports. South Africa's foreign direct investment and CO2 emissions have a cointegration relationship with the lag one period of exports, and South Africa's the lag one period of exports and foreign direct investment have a cointegration relationship with the lag one period of CO2 emissions. But whether it is China or South Africa, these three variables have no causal relationship in the long-term. Among the variables of other BRICS countries, Russia is the only country showed degenerate case #1 in McNown et al. mentioned in their paper. When we examined short-term causality, we found that CO2 emissions and export trade showed a reverse causal relationship, while FDI and carbon emissions were not so obvious. Export trade has a positive causal relationship with FDI. Those variables are different from different situations and different countries.
ARTICLE | doi:10.20944/preprints202011.0691.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: Huanglian Decoction (Coptidis Rhizoma, Zingiberis Rhizoma, Folium Artemisiae Argyi, Mume Fructus); Hepatocellular carcinoma; TCGA; GEO
Online: 27 November 2020 (13:14:24 CET)
Background: Hepatocellular carcinoma (HCC) is one of the most prevalent cancers in human populations worldwide. Conversely, Huanglian Decoction is one of the most important Chinese medicine formulas, with the potential to treat cancer. Methods: To identify differentially expressed genes (DEG), we herein downloaded gene expression profile data from the TCGA (TCGA-LIHC) and GEO (GSE45436) databases. We obtained phytochemicals of the four constituent herbs of Huanglian Decoction from the traditional Chinese medicine systems pharmacology database and analysis platform (TCMSP). We also established a regulatory network of DEG and their drug target genes and subsequently analyzed key genes using bioinformatic approaches. Furthermore, we explored the effect of Huanglian Decoction by conducting in vitro experiments so as to verify the prediction. In particular, the CCNB1 gene was knockdown to verify the primary target of this Decoction. Results: Based on the results of network pharmacological analysis, we revealed that there are 5 bioactive compounds in Huanglian Decoction acting on HCC. In addition, our findings confirmed that CCNB1 was the primary key gene, which can be highly expressed in tumors and was significantly associated with a worse prognosis (P = 0.002) according to PPI network analysis of the target genes of these five compounds, as well as expression and prognosis analyses in tumors. We also noted that CCNB1 can be used as an independent prognostic indicator of HCC (P < 0.01). Moreover, in vitro experimental results demonstrate that Huanglian Decoction can significantly inhibit the growth, migration, and invasion of HCC cells. Finally, further analysis showed that this Decoction may inhibit the growth of HCC cells by down-regulating the expression level of CCNB1.
ARTICLE | doi:10.20944/preprints201812.0079.v1
Subject: Engineering, Industrial And Manufacturing Engineering Keywords: mold flux; low fluorine; internal crack; surface roughness; slag film
Online: 6 December 2018 (08:40:10 CET)
As an essential synthetic material used in continuous casting of steels, mold fluxes improve the surface quality of steel slabs. In this study, a CaO-SiO2-Na2O based low-fluorine mold flux was solidified by an improved water-cooled copper probe with different temperatures of molten flux and different probe immersion times. The heat flux through solid films and the film structures were calculated and inspected, respectively. The results indicate: large internal cracks (formed in the glassy layer of films during solidification) were observed, the formation and evolution of those cracks contributed to the the unstable heat flux density. The roughness of the surface in contacted with the water-cooled copper probe formed as films were still glassy and the roughness have no causal relationship with crystallization or devitrification. Combeite with columnar and faceted dendritic shapes is the main crystal in the film.
ARTICLE | doi:10.20944/preprints201908.0175.v1
Subject: Engineering, Energy And Fuel Technology Keywords: wind turbine; wake; atmospheric stability; MOST; turbulence models
Online: 16 August 2019 (07:52:44 CEST)
Monin-Obukhov similarity theory (MOST) overestimates wind shear in some atmospheric stable conditions, i.e. Richardson number $R_f<0.25$. The overestimated wind shear that leads to an under-predicted friction wind speed and a lower ambient turbulence intensity for a given hub-height reference wind speed and a given roughness length, could influence wake modeling of a wind turbine. This work investigates the side effects of the breakdown of MOST on wake modeling under stable conditions and makes some modifications to the flow similarity functions to eliminate these side effects. Based on a field measurement in a wind farm, we firstly show that MOST predicts a larger wind shear for the atmospheric stability parameter $\zeta>0.1$ and proposes new flow similarity functions without constraining $R_f$ to limit the overestimated wind shear by MOST. Next, different turbulence models based on MOST and a modified one based on the new similarity functions are investigated through numerical simulations. These turbulence models are combined with the actuator disk model (AD) and Reynolds-averaged Navier–Stokes equations (RANS) to model wind turbine wakes under stable conditions. As compared to measurements, numerical results show that turbulence models based on MOST result in larger wake deficits and slower wake recovery rate with a square root of the mean-squared-error (RSME) of wake deficit in the range of 0.07-0.18. This overestimated wake effect is improved by applying the new similarity functions and the RSME of wake deficit is averagely reduced by 0.05. Finally, we check the role of the under-predicted turbulence intensity playing in the larger wake deficit predicted by models based MOST. Additional numerical simulations using the modified turbulence model are carried out, in which the roughness length is reduced to impose a hub-height ambient turbulence intensity equivalent to the MOST case. Simulation results show that reducing turbulence intensity enhances wake effects, however, it cannot reproduce the large wake deficit predicted by models based on MOST, which suggests that the overestimated wake effect by MOST could be also related to the overestimated wind shear.
ARTICLE | doi:10.20944/preprints201907.0029.v1
Subject: Engineering, Energy And Fuel Technology Keywords: wind turbine; wake; atmospheric stability; actuator disk; BEM
Online: 2 July 2019 (04:11:13 CEST)
Atmospheric stability affects wind turbine wakes significantly. High-fidelity approaches such as large eddy simulations (LES) with the actuator line (AL) model which predicts detailed wake structures, fail to be applied in wind farm engineering applications due to its expensive cost. In order to make wind farm simulations computationally affordable, this paper proposes a new actuator disk model (AD) based on the blade element method (BEM) and combined with Reynolds-averaged Navier–Stokes equations (RANS) to model turbine wakes under different atmospheric stability conditions. In the proposed model, the upstream reference velocity is firstly estimated from the disk averaged velocity based on the one-dimensional momentum theory, and then is used to evaluate the rotor speed to calculate blade element forces. Flow similarity functions based on field measurement are applied to limit wind shear under strongly stable conditions, and turbulence source terms are added to take the buoyant-driven effects into consideration. Results from the new AD model are compared with field measurements and results from the AD model based on the thrust coefficient, the BEM-AD model with classical similarity functions and a high-fidelity LES approach. The results show that the proposed method is better in simulating wakes under various atmospheric stability conditions than the other AD models and has a similar performance to the high-fidelity LES approach however in much lower computational cost.
COMMUNICATION | doi:10.20944/preprints202107.0160.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: Teleost fish; Exosome; Immunity; Mx1; ISKNV
Online: 6 July 2021 (14:58:24 CEST)
Exosomes are associated with cancer progression, pregnancy, cardiovascular diseases, central nervous system–related diseases, immune responses and viral pathogenicity. However, study on the role of exosomes in the immune response of teleost fish, especially antiviral immunity, is limited. Herein, serum-derived exosomes from mandarin fish were used to investigate antiviral effect for the exosomes of teleost fish. Exosomes were isolated from mandarin fish serum by ultracentrifugation could internalize into Mandarin fish fry (MFF-1) cells and inhibited Infectious spleen and kidney necrosis virus (ISKNV) infection. To further investigated the underlying mechanisms of exosomes in inhibiting ISKNV infection. The protein composition of serum-derived exosomes was by analysis mass spectrometry and found that myxovirus resistance 1 (Mx1) was incorporated in the exosomes. Furthermore, the scMx1 protein was proved transferred to the recipient cells though the exosomes. Our results found that the serum-derived exosomes from mandarin fish could inhibit ISKNV replication and suggested an underlying mechanism of the serum-derived exosomes antivirus is that serum-derived exosomes incorporation of the Mx1 protein into exosomes and delivery into recipient cells. This study provided an evidence for the important antiviral role of exosomes in the immune system of teleost fish.
ARTICLE | doi:10.20944/preprints202311.0184.v1
Subject: Biology And Life Sciences, Horticulture Keywords: peach; amino acid; drought stress; osmotic; physiological index
Online: 3 November 2023 (01:32:00 CET)
Peach (L.) is a kind of fruit tree with considerable economic and nutritional significance. However, it shows a high sensitivity to drought stress, which has a profound impact on its growth. L-methionine (MET) and L-proline (PRO) are two amino acids synthesized by plants, which play an important role in abiotic stress response. However, their exact mechanism of action remains elusive. Through physiological analysis, MET (500ppm) and PRO (500ppm) treatments can effectively reduce the adverse effects of drought stress on the growth of peach seedlings. Studies have shown that amino acid (AA) can effectively inhibit the stomatal opening of plant leaves and increase the photosynthetic rate. In addition, the application of MET or PRO promoted the accumulation of carbohydrates in leaf tissues, increased intracellular water potential (24%, 24%), reduced osmotic potential (21%, 24%), and alleviated membrane damage caused by drought. Using Evans Blue, nitroblue tetrazolium (NBT) and DAB (3, 3-diaminobenzidine) staining experiments, We confirmed that the increase in antioxidant enzyme activity in leaves may be due to the removal of reactive oxygen species (ROS) in vivo, namely the downregulation of malondialdehyde (18%, 19%) ，peroxidase (50%, 5%) and superoxide dismutase (12%, 14%) activities. In addition, the application of exogenous amino acids also improved the root morphology and vitality of peach seedlings, which was conducive to absorbing external buffer substances and alleviating drought stress. In summary, the application of exogenous amino acids can effectively alleviate the effects of drought stress on plants and reduce the harm.
ARTICLE | doi:10.20944/preprints201807.0470.v1
Subject: Chemistry And Materials Science, Food Chemistry Keywords: Arthrospira platensis; carotenoids; natural pigments; spirulina powder; C-phycocyanin; antioxidant activity
Online: 25 July 2018 (06:19:11 CEST)
Arthrospira platensis is the widely available source of spirulina and contains distinctive natural pigments including carotenoids and C-phycocyanin (C-PC). In this study, the major carotenoid and C-PC contents were determined in seven commercially available spirulina powder products and laboratory-prepared A. platensis trichomes (AP-1) by an LC-DAD method and a UV-Visible spectrometry, respectively. The correlation of these two pigment content levels with Hunter color coordinates and antioxidant activity was also evaluated. The L* value failed to show a significant correlation with pigment content, but a positive correlation was observed between a* values and the contents of total carotenoid and C-PC. As b* values decreased, the total carotenoid and C-PC contents increased. AP-1 exhibited the highest content of total carotenoids, chlorophyll a and C-PC, and antioxidant activities among the samples. This observation could be related to degradation of these pigments during the mass production process. The carotenoid profiles suggested that the commercial spirulina powders originated from two different sources, A. platensis and A. maxima. Total carotenoid and C-PC content exhibited positive significant correlations with antioxidant activities measured by DPPH and ABTS assays. These results provide a strong scientific foundation for the establishment of standards for the commercial distribution of quality spirulina products.
REVIEW | doi:10.20944/preprints202306.1873.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: Bacterial Extracellular Vesicles; Therapeutics; Neurodegenerative Disease; Alzheimer's Disease; Nanocarriers
Online: 27 June 2023 (09:27:15 CEST)
Bacterial Extracellular Vesicles (BEVs) generated from the bacteria has high feasibility of intracellular interactions with other cells, can be used as a cargo to deliver any therapeutic substances like monoclonal antibodies, proteins, plasmids, siRNA and small molecules for the treatment of neurodegenerative diseases (NDs). BEVs have a high ability for delivering therapeutic molecules across the blood-brain barrier to treat Alzheimer's Disease (AD) via various mechanisms. In this review, we have sum up in-depth research details of the role and advancement of BEVs in NDs, AD and its Therapeutics. Moreover, details about offensive and defensive functions of BEVs in ND pathogenesis and examine the critical BEV networks in the microbiome-gut-brain axis and their role in neurodegenerative disorders. Additionally determining the roles of BEVs in the neuroimmune system and their interaction with neurodegenerative disorders and exploring the risk factors of BEVs in the autophagy-lysosomal pathway and their possible effects on neurodegenerative disorders are summarised in detail. In conclusion, this review seeks to contribute to a better understanding of the potential function of BEVs in NDs and to identify new therapeutic intervention strategies.
ARTICLE | doi:10.20944/preprints201809.0349.v1
Subject: Chemistry And Materials Science, Organic Chemistry Keywords: coumarin; one-pot synthesis; catalysis; Wells–Dawson heteropolyacid
Online: 18 September 2018 (11:53:28 CEST)
The development of a method to produce coumarins unsubstituted on the pyranic nucleus catalyzed from Wells–Dawson heteropolyacid (H6P2W18O62), phenol derivatives and ethyl 3,3-diethoxypropionate using Pechmann condensation under solvent-free conditions is described. This catalytic method was also applied successfully to synthesize various substituted coumarins, including the corresponding phenols and ethyl 3,3-diethoxypropionate. This work provides a novel, cheaper and safer way to syhthesize coumarins unsubstituted on the pyranic nucleus.
REVIEW | doi:10.20944/preprints202308.0319.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: lithium iron phosphate (LFP); nickel-cobalt-manganese (NCM); cathode materials; power battery; cycle life; attenuation mechanism
Online: 3 August 2023 (09:30:37 CEST)
In the past decade, under the background of the carbon peaking and carbon neutrality era, the rapid development of new energy vehicles has put forward higher requirements for the performance of strike forces such as battery cycle life, energy density and cost. Lithium-ion batteries have gradually become the mainstream of electric vehicle power batteries due to their excellent energy density, rate performance and cycle life. At present, the most widely used cathode materials for power batteries are lithium iron phosphate (LFP) and ternary nickel-cobalt-manganese (NCM). However, these materials exhibit the bottlenecks that limit the improvement and promotion of power battery performance. In this review, the performance characteristics, cycle life attenuation mechanism (including structural damage, gas generation and active lithium loss, etc.) and improvement methods (including surface coating and element-doping modification) of LFP and NCM batteries are reviewed. Finally, the development prospects of this field are proposed.