ARTICLE | doi:10.20944/preprints201708.0037.v1
Subject: Physical Sciences, Acoustics Keywords: meshfree method; particle-based computational acoustics; smoothed particle hydrodynamics; corrective smoothed particle method; boundary conditions; Lagrangian approach
Online: 10 August 2017 (05:20:33 CEST)
Meshfree particle method, which is always regarded as a pure Lagrangian approach, is easily represented complicated domain topologies, moving boundaries, and multiphase media. Solving acoustic problems with the mesfree particle method forms a branch of the acoustic wave modeling field, namely, particle-based computational acoustics (PCA). The aim of this paper is to improve the accuracy of using the PCA method to solve two-dimensional acoustic problems, and realize the particle representation with a hybrid meshfree and finite-difference time-domain (FDTD) method for acoustic boundary conditions at both the plane and curved surface. As a widely used Lagrangian meshfree method, the smoothed particle hydrodynamics (SPH) based on the support domain and the kernel function has developed rapidly in recent years. The traditional SPH method is easily implements parallel processing and has been applied in sound wave simulation. As a corrective method with higher accuracy than SPH, the acoustic propagation and scattering in the time domain is simulated with the corrective smoothed particle method (CSPM). Moreover, a hybrid meshfree-FDTD boundary treatment technique is utilized to represent different acoustic boundaries in the Lagrangian approach. In this boundary treatment technique, the parameter value of virtual particles is obtained with the FDTD method, which concerns truncation errors based on the Tayler series expansion. Soft, rigid, and Mur’s absorbing boundary conditions are developed to simulate sound waves in finite and infinite domain. Results of modeling acoustic propagation and scattering show that CSPM is accurate and convergence with exact solutions, and different acoustic boundaries are validated to be effective in the computation.
ARTICLE | doi:10.20944/preprints202310.0520.v1
Subject: Environmental And Earth Sciences, Geochemistry And Petrology Keywords: chrysoberyl; Raman; trace elements; CIELab
Online: 10 October 2023 (03:19:18 CEST)
In this study, seventeen faceted gem-quality chrysoberyls exhibiting an attractive canary yellow color were investigated by a series of gemological, spectral, and chemical methods. Microscopic observation reveals distinct growth lines and inclusions, including CO2 fluids, carbon, and mineral crystals such as calcite, quartz, sillimanite, and mica, identified by the Raman spectrum. The FTIR spectrum exhibits the 2405 and 2160 cm-1 feature peaks and a 3223 cm-1 peak in all samples, which can be accompanied by the 3112 cm-1 shoulder, 3301, and 3412 and 3432 cm-1 peaks. The UV-Vis spectrum shows a Fe-related peak at 440 nm, along with the 650–660 nm band and the absorption band in the blue zone of the visible light. The chemical results of EDXRF reveal a V-poor, Cr-poor, and Fe-rich feature. The spectral and chemical results could contribute to explaining the origin of the canary yellow color, which originates from the abundant amount of Fe with very little influence from Cr or V.
ARTICLE | doi:10.20944/preprints202304.1157.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: neonicotinoids; imidacloprid; heat treatment; rice; drinking water
Online: 28 April 2023 (09:45:10 CEST)
Neonicotinoids (NEOs) have become the most widely used insecticides in the world since the mid-1990s. According to Chinese dietary habits, rice and water are usually heated before being consumed, but the information about the alteration through the heat treatment process is very limited. In this study, the parents of NEOs (p-NEOs) accounted for >99% of the total NEOs mass (∑NEOs) in both uncooked (median: 66.8 ng/g) and cooked (median: 41.4 ng/g) rice samples from Guangdong Province, China, while the metabolites of NEOs (m-NEOs) involved in this study accounted for less than 1%. We aimed to reveal the concentration changes of NEOs through heat treatment process, thus, several groups of rice and water samples from Guangdong were cooked and boiled, respectively. Significant (p < 0.05) reductions in acetamiprid, imidacloprid (IMI), thiacloprid, and thiamethoxam (THM) have been observed after the heat treatment of the rice samples. In water samples, the concentrations of THM and dinotefuran decreased significantly (p < 0.05) after the heat treatment. These results indicate the degradation of p-NEOs and m-NEOs during the heat treatment process. However, the concentrations of IMI increased significantly in tap water samples (p < 0.05) after heat treatment process, which might be caused by the potential IMI precursors in those industrial pesticide products. The concentrations of NEOs in rice and water can be shifted by the heat treatment process, so this process should be considered in relevant human exposure studies.
ARTICLE | doi:10.20944/preprints202305.1611.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: oxygen evolution reaction; transition metal selenides; multilayer nanosheets; carbon quantum dots; Heterostructures
Online: 23 May 2023 (08:07:30 CEST)
Oxygen evolution reaction is a momentous part of electrochemical energy storage and conversion devices such as rechargeable metal-air batteries. It is particularly urgent to develop low-cost and efficient electrocatalysts for oxygen evolution reactions. As a potential substitute for noble metal electrocatalysts, transition metal selenides are still challenging in improving the activity of oxygen evolution reaction and the research of reaction intermediates. In this study, a simple one-step solvothermal method was used to prepare a polymetallic compound carbon matrix composite (Co9Se8/Ni3Se4/Fe3O4@C) with a multilayered nanosheets structure. It exhibited good OER activity in an alkaline electrolyte solution with an overpotential of 268 mV at 10 mA/cm2 in an alkaline medium. Besides, this catalyst also showed excellent performance in the 24 hours stability test. The composite presents a multi-layer sheet structure, which effectively improves the contact between the active site and the electrolyte. The selenide formed by Ni and Co has a synergistic effect, Fe3O4 and Co9Se8 form a heterojunction structure, which can effectively improve the reaction activity by initiating the electronic coupling effect through the interface modification. In addition, carbon quantum dots have rich heteroatoms and electron transferability, which improves the electrochemical properties of the composites. This work provides a new strategy for the preparation of highly efficient OER electrocatalysts utilizing the multimetal synergistic effect.
REVIEW | doi:10.20944/preprints202305.1444.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: Gamma-aminobutyric acid; subtype; analgesic effect; mechanism
Online: 19 May 2023 (15:03:06 CEST)
Gamma-aminobutyric acid (GABA), a non-protein-producing amino acid, is extensively found in microorganisms, plants and vertebrates, and is abundantly expressed in the spinal cord and brain. To date, GABA is considered to be the major inhibitory neurotransmitter in the central nervous system. Its physiological effects are related to the regulation of synaptic transmission, the promotion of neuronal development and relaxation, and the prevention of insomnia and depres-sion. Mediated through its specific receptors, it plays a pivotal role in the control of neuronal ex-citability, which can serve as anovel target for developing analgesics for pain management. This review provides an update on the accumulating evidence of specific GABA receptors and their subtypes in the involvement of pain analgesia.
ARTICLE | doi:10.20944/preprints202210.0283.v1
Subject: Biology And Life Sciences, Horticulture Keywords: GABA; hardy kiwifruit; respiration rate; ethylene; storage
Online: 19 October 2022 (10:26:48 CEST)
γ-Aminobutyric acid (GABA) plays an important role in plant development and postharvest properties of fruits. However, studies on regulation of kiwifruit ripening by GABA are scarce. Here, we evaluted physicochemical characters and the expression profile of genes related to ripening in hardy kiwifruit treated with exogenous GABA compared to control during postharvest storage period. The results showed that (1) exogenous GABA treatment not only improved the fruit quality but also inhibited respiration rate and ethylene production, as well as reduced the enzyme activities of ACC oxidase (ACO) and ACC synthase (ACS), via down-regulating the expression of AaACO1 and AaACO3, AaACS1 and AaACS2 during kiwifruit storage period; (2) on the one hand, overexpression of AaGAD1 or AaGAD4 gene which is involved in GABA biosynthesis inhibited ethylene production by reducing the enzyme activities of ACO and ACS, whereas silencing of AaGAD1 or AaGAD4 gene led to the reverse effect. On the other hand, overexpression of AaGAD1 or AaGAD4 decreased the expression levels of AaACO1 and AaACO3, AaACS1 and AaACS2, whereas silencing of AaGAD1 or AaGAD4 gene increased the expression levels of these four genes. Above all, our findings demonstrate that exogenous GABA treatment could improve the storage quality and extend the shelf life of kiwifruit, Additionally, the content of GABA was participated in the regulation of ethylene biosynthesis at the molecular level.
ARTICLE | doi:10.20944/preprints202210.0063.v1
Subject: Chemistry And Materials Science, Organic Chemistry Keywords: Antifungal activities; synthesis; indole Schiff base derivatives; 1,3,4-thiadiazole
Online: 6 October 2022 (10:27:10 CEST)
A series of novel indole Schiff base derivatives (2a–2t) containing a 1,3,4-thiadiazole scaffold modified with a thioether group were synthesized, and their structures were confirmed using FT-IR, 1H NMR, 13C NMR, andHR-MS. In addition, the antifungal activity of synthesized indole derivatives was investigated against Fusarium graminearum (F. graminearum), Fusarium oxysporum (F. oxysporum), Fusarium moniliforme (F. moniliforme), Curvularia lunata (C. lunata), and Phytophthora parasitica var. nicotiana (P. p. var. nicotianae) using the mycelium growth rate method. Among the synthesized indole derivatives, compound 2j showed the highest inhibition rates of 100%, 95.7%, 89%, and 76.5% at a concentration of 500 μg/mL against F. graminearum, F. oxysporum, F. moniliforme, and P. p. var. nicotianae, respectively. Similarly, compounds 2j and 2q exhibited higher inhibition rates of 81.9% and 83.7% at a concentration of 500 μg/mL against C. lunata. In addition, compound 2j has been recognized as a potential compound for further investigation in the field of fungicides.
ARTICLE | doi:10.20944/preprints202003.0286.v1
Subject: Medicine And Pharmacology, Pharmacy Keywords: COVID-2019; SARS-CoV-2; repurposing; network bioinformatics
Online: 18 March 2020 (08:50:10 CET)
The COVID-2019 disease caused by the SARS-CoV-2 virus (aka 2019-nCoV) has raised significant health concerns in China and worldwide. While novel drug discovery and vaccine studies are long, repurposing old drugs against the COVID-2019 epidemic can help identify treatments, with known preclinical, pharmacokinetic, pharmacodynamic, and toxicity profiles, which can rapidly enter Phase 3 or 4 or can be used directly in clinical settings. In this study, we presented a novel network based drug repurposing platform to identify potential drugs for the treatment of COVID-2019. We first analysed the genome sequence of SARS-CoV-2 and identified SARS as the closest disease, based on genome similarity between both causal viruses, followed by MERS and other human coronavirus diseases. Using our AutoSeed pipeline (text mining and database searches), we obtained 34 COVID-2019-related genes. Taking those genes as seeds, we automatically built a molecular network for which our module detection and drug prioritization algorithms identified 24 disease-related human pathways, five modules and finally suggested 78 drugs to repurpose. Following manual filtering based on clinical knowledge, we re-prioritized 30 potential repurposable drugs against COVID-2019 (including pseudoephedrine, andrographolide, chloroquine, abacavir, and thalidomide) . We hope that this data can provide critical insights into SARS-CoV-2 biology and help design rapid clinical trials of treatments against COVID-2019.
ARTICLE | doi:10.20944/preprints201701.0067.v1
Subject: Physical Sciences, Mathematical Physics Keywords: computational acoustics; meshfree method; Lagrangian approach; smoothed particle hydrodynamics; corrective smoothed particle method; boundary conditions; numerical method
Online: 13 January 2017 (10:09:35 CET)
The development of computational acoustics allows simulation of sound generation and propagation in complex environment. In particular, meshfree methods are widely used to solve acoustics problems through arbitrarily distributed field points and approximation smoothness flexibility. As a Lagrangian meshfree method, smoothed particle hydrodynamics (SPH) method reduce the difficulty in solving problems with deformable boundaries, complex topologies, or multiphase medium. The traditional SPH method has been applied in acoustic simulation. This study presents the corrective smoothed particle method (CSPM), which is a combination of SPH kernel estimate and Taylor series expansion. The CSPM is introduced as a Lagrangian approach to improve accuracy in solving acoustic wave equations in the time domain. Moreover, a boundary treatment technique based on the hybrid meshfree and finite difference time domain (FDTD) method is proposed to represent different acoustic boundaries with particles. To model sound propagation in pipes with different boundaries, soft, rigid, and absorbing boundary conditions are built with this technique. Numerical results show that the CSPM algorithm is consistent and demonstrates convergence with exact solutions. Main computational parameters are discussed, and different boundary conditions are validated to be effective for benchmark problems in computational acoustics.
ARTICLE | doi:10.20944/preprints201611.0107.v1
Subject: Medicine And Pharmacology, Gastroenterology And Hepatology Keywords: pancreatic cancer; deguelin; autophagy; doxorubicin
Online: 21 November 2016 (10:01:23 CET)
Pancreatic cancer is the fourth most common cause of cancer mortality worldwide. Furthermore, patients with pancreatic cancer experience limited benefit from current chemotherapeutic approaches because of drug resistance. Therefore, an effective therapeutic strategy for patients with pancreatic cancer is urgently required. Deguelin is a natural chemopreventive drug that exerts potent antiproliferative activity in solid tumors by inducing cell death. However, the molecular mechanisms underlying this activity have not been fully elucidated. Here we show that deguelin blocks autophagy and induces apoptosis in pancreatic cancer cells in vitro. Autophagy induced by doxorubicin plays a protective role in pancreatic cancer cells, and suppressing autophagy by chloroquine or silencing autophagy protein 5 enhanced doxorubicin-induced cell death. Similarly, inhibition of autophagy by deguelin also chemosensitized pancreatic cancer cell lines to doxorubicin. These findings suggest that deguelin has potent anticancer effects against pancreatic cancer and potentiates the anti-cancer effects of doxorubicin. These findings provide evidence that combined treatment with deguelin and doxorubicin represents an effective strategy for treating pancreatic cancer.