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Blockchain has become one of the key techniques for the security of the industrial internet. However, the blockchain is vulnerable to FAW (Fork after Withholding) attacks. To protect the industrial internet from FAW attacks, this paper proposes a novel FAW attack protection algorithm (FAWPA) based on the behavior of blockchain miners. Firstly, FAWPA performs miner data preprocessing based on the behavior of the miners. Then, FAWPA proposes a behavioral reward and punishment mechanism and a credit scoring model to obtain cumulative credit value with the processed data. Moreover, we propose a miner's credit classification mechanism based on fuzzy C-means (FCM), which combines the improved Aquila optimizer (AO) with strong solving ability. That is, FAWPA combines the miner's accumulated credit value and multiple attack features as the basis for classification, and optimizes cluster center selection by simulating Aquila's predation behavior. It can improve the solution update mechanism in different optimization stages. FAWPA can realize the rapid classification of miners' credit levels by improving the speed of identifying malicious miners. To evaluate the protective effect of the target mining pool, FAWPA finally establishes a mining pool and miner revenue model under FAW attack. The simulation results show that FAWPA can thoroughly and efficiently detect malicious miners in the target mining pool. FAWPA also improves the recall rate and precision rate of malicious miner detection, and it improves the cumulative revenue of the target mining pool. The proposed algorithm performs better than ND, RSCM, AWRS, and ICRDS. [ABSTRACT FROM AUTHOR]

A novel highly active silver single-atom catalyst (AgSAC) was prepared by a microwave-assisted solvothermal method using silver covalent organic frameworks (AgMOF) as precursors. It was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared (IR), and surface-enhanced Raman scattering (SERS). The experiment found that AgSAC has excellent catalytic performance and can heavily catalyze the nano-reaction of chloroauric acid-malic acid (HAuCl 4 –H 2 Mi) to generate gold nanoparticles (AuNPs). The produced AuNPs have strong SERS, resonance Rayleigh scattering (RRS) and surface plasmon resonance absorption (Abs) signals. Aflatoxin B1 aptamer (Apt AFB1) can be adsorbed to the surface of AgSAC through electrostatic interaction, to reduce the catalytic activity of AgSAC and the SERS/RRS/Abs signal of the system. When the target molecule (AFB1) was added, it will specifically bind to Apt AFB1 and release AgSAC, restoring the catalytic activity of AgSAC, thereby restoring the SERS/RRS/Abs signal of the system. Based on this, a simple and sensitive aptamer sensing analysis platform for trace AFB1 was established, and a reasonable catalytic amplification mechanism of AgSAC was proposed. The SERS method exhibited the highest sensitivity, with a linear range of 0.005–0.225 μg/L and a detection limit of 0.002 μg/L. Principle of aptamer-mediated SERS/RRS for AFB1 based on AgSAC catalysis. [Display omitted] • A highly active silver single-atom catalyst (AgSAC) was synthesized with AgMOF. • A new AgSAC-HAuCl 4 -H 2 Mi catalytic indicator was constructed. • The nanocatalytic amplification reaction was coupled with aptamer mediation. • A highly sensitive SERS/RRS platform was proposed for trace Aflatoxin B1. [ABSTRACT FROM AUTHOR]

Background: Wogonin, a natural flavonoid-like chemical compound, exhibits anti-inflammatory, antitumor, antiviral, neuroprotective, and anxiolytic effects by modulating a variety of cellular signaling pathways including PI3K-Akt, p53, nuclear factor κB (NF-κB), mitogen-activated protein kinase (MAPK) pathways. In this study, its antiviral effect against herpes simplex virus (HSV) type 1 and 2 (HSV-1 and HSV-2) replication was investigated. Results: Wogonin suppressed HSV-2-induced cytopathic effect (CPE) and reduced viral mRNA transcription, viral protein synthesis, and infectious virion particle titers in a dose-dependent manner. A time-of-drug-addition assay demonstrated that wogonin acted as a postentry viral inhibitor. Wogonin also significantly reduced HSV-induced NF-κB and MAPK pathway activation, which has previously been demonstrated to be important for viral replication. Conclusions: Our results suggest that the anti-herpes effect of wogonin may be mediated by modulation of cellular NF-κB and JNK/p38 MAPK pathways and imply that wogonin may be useful as an anti-HSV agent. [ABSTRACT FROM AUTHOR]

Selective laser melting (SLM) is a 3D printing technology suitable for manufacturing high-precision metal parts with complex geometries. At present, the research on SLM technology to produce high performance, complex structures made of superalloy parts has become the focus of aerospace and other fields. In this work, the microstructure, microhardness, and tensile strength of an Inconel 718 superalloy synthesized using SLM technology were first investigated. Then, the wear characteristics of the alloy at various temperatures were examined by multifunctional friction and wear testing equipment. Finally, a thorough analysis of the wear damage mechanisms of the materials over a wide temperature range was performed. The grains of the Inconel 718 superalloy formed by SLM developed as columnar grains that were more evenly and firmly dispersed along the horizontal axis. The material had a slightly greater microhardness in the vertical plane (HV 1 =346) than in the horizontal plane (HV 1 =324). A tensile test revealed that the horizontal tensile strength of SLM-formed Inconel 718 alloy was 50.1 MPa higher than that in the vertical direction, while the elongation was 0.14 % lower than the latter. The fracture mechanism of the material presented a fracture type dominated by microporous aggregation. A friction wear test showed that the friction wear coefficient of the SLM-formed Inconel 718 alloy gradually decreased with temperature. Abrasive wear, oxidative wear, and adhesive wear were the main wear mechanisms for the material during wear testing in the high temperature environments. The wear surface of the alloy material generated an oxide layer at 650 °C, which was effective in lowering friction and wear. [ABSTRACT FROM AUTHOR]

Abstract: The scandal of melamine-adulterated infant formula in China in September 2008 demanded the need to assess the extent of melamine contamination in the environment and food products and possible risks of consuming melamine-contaminated diets. In this work, our extensive work tested water, soil and crop samples from 21 provinces in China. Soils nearby and waste waters from melamine-manufacturing factories were examined, and the highest melamine concentrations in waste water and soil samples were 226.766 and 41.136mg/kg, respectively. Six of 94 irrigation water samples had melamine at a concentration of 21–198μg/L. Only 1 sample collected from 124 farmlands farther than 150km from melamine factories was detected for melamine at a content of 176μg/L. Only 3 out of 557 crop samples contaminated more than 1mg/kg melamine, with the highest level of 2.05mg/kg in a wheat sample. When basal diets contained 2mg/kg melamine were fed to various animals, deposition of melamine in animal tissues and products was all lower than 122μg/kg. The melamine deposition was much higher (e.g., 4483μg/kg in the kidney of chicken) when diets contained 100mg/kg melamine but was found to be completely depleted after 96h for all animals after switching to the basal diets. Our work may be valuable to regulate melamine production and monitor the safety of food and animal products. [Copyright &y& Elsevier]

Abstract: The degradation of intracytosolic proteins has been well described. However, the degradation pathway and physiological functions of the DNA-Bound peptides, which are free of degradation by peptidase of the post-ubiquitin–proteasome pathway, are still unclear. In this study, the DNA-Bound peptides were isolated from barley germ and two main fractions of about 25 different peptides were obtained. The DNA-Bound peptides were found to inhibit the proliferation of HeLa cells in a series of experiments. The DNA-Bound peptides also significantly inhibited in vitro and in vivo DNA transcription activity by regulating the expression and the corresponding functions of CDK7. Furthermore, signaling issues involving NFκB and ERK1/2 were observed. Such data suggests that DNA transcription could be inhibited by the DNA-Bound peptides via the CDK7 pathway. Thus we concluded that some of the post-proteasomal peptides were involved in the regulation of eukaryotic mRNA transcription. [Copyright &y& Elsevier]

A new method for the determination of oxytetracycline (OTC) has been established by coupling the catalytic amplification reaction of copper nanoclusters (CuNCs) with the aptamer reaction. CuNCs prepared by a wet chemical method have the catalytic activity for the formation of gold nanoparticles (AuNPs) resulting from a HAuCl4-ethanol (En) reaction. The experimental results showed that OTC aptamer (Apt) can be adsorbed on the surface of CuNCs in a non-specific way, thus inhibiting its catalytic activity. When OTC was added to the solution, the OTC-Apt complex was generated by a specific reaction, which made the CuNCs desorb and restore their catalytic activity. With the increase of OTC, the recovery of the catalytic activity of CuNCs is strengthened, the reaction speed is accelerated, and the number of AuNPs is increased. The generated AuNPs exhibited surface enhanced Raman scattering (SERS) signals at 1615 cm−1 in the presence of Vitoria blue 4R (VB4R) molecular probes, and a resonance Rayleigh scattering (RRS) peak at 586 nm. There is a good linear relationship between the intensities of SERS, or RRS, and OTC concentration at the range of 37.5–300 ng/L or 37.5–225 ng/L, respectively. A new SERS and RRS assay for the determination of trace OTC based on the regulation of CuNCs catalysis was established. [ABSTRACT FROM AUTHOR]

Background: The pattern recognition receptors (PPRs) are the earliest phase of the host defense against pathogens in genital epithelium, and toll-like receptors (TLRs) are best characterized PPRs mediating innate immune responses. Herpes simplex virus type 2 (HSV-2), a member of herpesviridae family, causes one of the most prevalent sexually transmitted infection in the world. In this paper, we described that HSV-2 infection would induce activator protein 1 (AP-1) via TLR4-MyD88/TRIF pathway in human genital epithelial cell. Methods: TLRs expression profiles and changes was investigated in HSV-2-infected cells. The effect of TLR4-MyD88/TRIF on HSV-2-induced AP-1 activation and viral replication was also evaluated. The TLR4 translocation change was examined after viral infection. Finally, viral ICP0 effect on TLR4 signaling and TLR4-promoter regulation were primarily studied. Results: HSV-2-induced AP-1 activation was dependent on TLR4 and downstream adaptor molecules MyD88 and TRIF. And also, TLR4, MyD88 and TRIF was proved to affect HSV-2 replication. AP-1 activation would also be enhanced via overexpression of myeloid differentiation protein 2 (MD2), implicating that it might be a necessary accessory for TLR4 to sense HSV-2 infection. Protein quantification of cytoplasmic and membrane-associated TLR4 revealed that HSV-2 infection increased membrane-anchoring TLR4 level, but not cytoplasmic ones. Viral ICP0 could augment cellular AP-1, TLR4 promoter activation and TLR4 expression level. The specific inhibitor treatment and transcription factor binding site scanning in TLR4 promoter region showed that AP-1 activity was essential for TLR4-promoter activation. Conclusions: Taken together, HSV-2 infection could stimulate AP-1 activation via TLR4-MyD88/TRIF axis, and then feedback to up-regulate TLR4 expression in human genital epithelial cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ce-MOF is used as a molecular probe of RRS to quantitatively detect trace formaldehyde. • Formaldehyde derivative and Ce-MOF were coupled to generate energy transfer. • This method aims to combine the traditional spectrophotometric with the existing RRS technology. • A convenient detection of trace formaldehyde is realized. Formaldehyde (HCHO) is a widespread toxic pollutant, and the content of formaldehyde in food directly affects human health. Therefore, it is particularly important to establish and develop a rapid and accurate method for the determination of trace formaldehyde to ensure food safety. Metal-organic framework (MOF) has the characteristics of both organic and inorganic materials, which can be applied in various fields. What's more, Cerium (Ce) is the most abundant rare earth element. So far, it has no report about using Ce-MOF as a molecular probe of resonance Rayleigh scattering (RRS). The purpose of this research is to establish a new method for formaldehyde by combining the highly selective acetylacetone reaction with the sensitive RRS technology. When formaldehyde is added, acetylacetone reacts with it to form a complex (DDL), which acts as an accepter. There is a RRS-energy transfer (ET) between the DDL and Ce-MOF (act as the donor) because of spectral overlap. As a result, the RRS intensity of the Ce-MOF system decreased with formaldehyde concentration increase. So, Ce-MOF is used as a molecular probe of RRS to detect formaldehyde. In this study, the detection limit of formaldehyde was 0.063 µmol/L, and the determination range was 0.067–66.67 µmol/L. Compared with other methods, this method is simple in pretreatment and operation, and has a lower detection limit. Thus, a convenient detection of trace formaldehyde is realized. [ABSTRACT FROM AUTHOR]

In recent years, Hybrid Cellular Automata Method (HCAM) has been successfully applied to solve structural topology optimization problems. However, there was no report on HCAM research of three-dimensional composite structure composed of multiple materials and multiple bodies. Therefore, in this paper, three-dimensional non-cube cells of irregular size (such as tetrahedral cells with adaptive changes inside length) and Finite Element Method (FEM) are introduced to extend HCAM, which is better and more flexibly to fit complex geometric shapes. Furthermore, a better structure configuration of multi-material and multi-body structure is obtained. The typical example study showed that the proposed topology optimization method could effectively remove the redundant materials of multi-material and multi-body structure, and the optimized structure configuration could still meet the requirements of the original condition after geometric reconstructed. Thus it provided a reference for the intelligent design of other products. [ABSTRACT FROM AUTHOR]

Spaceborne time series SAR interferometry (TS-InSAR) technology has been widely applied in ground deformation monitoring. The current popular TS-InSAR are carried out mainly on permanent scatterers (PS) or distributed scaterrers (DS), which can map the ground deformation on sparse targets with high or moderate coherence. However, high-precision and high-density deformation monitoring is always restricted by atmospheric artifacts and surface decorrelation, especially over nonurban areas. Here we show that the ground deformation can be precisely mapped with high density by spaceborne InSAR technique. We proposed a full scatterers InSAR (FS-InSAR) methodology, which can significantly improve the quality of the interferograms by applying a dual-scale temporal low-pass filter (DTLF) to separate both atmospheric and noisy phases from deformation phases, without external atmospheric data. Simulation experiments were conducted to determine the small-scale and large-scale window sizes and evaluate the effectiveness of DTLF. Then we applied the FS-InSAR method to the Tianjin-Tangshan region, China using Sentinel-1 data, assessed the regenerated differential low-frequency phases, and validated the results with leveling measurements and groundwater depth data. What's more, detailed ground deformation was retrieved over the Tangshan mining area with an unprecedented density of 98.55%. Our results demonstrate that the FS-InSAR strategy contrasts sharply with the previous PS-InSAR or DS-InSAR methods by simultaneously solving the two bottleneck problems of atmospheric artifacts and decorrelation in most cases except for water bodies or dense vegetations such as rainforest, thereby it is of great importance for future monitoring and understanding the ground deformation to prevent and control geological disasters. • FS-InSAR can effectively remove atmospheric artifacts without external data. • FS-InSAR significantly improves the quality of the interferograms. • FS-InSAR can map ground deformation with an unprecedented density. [ABSTRACT FROM AUTHOR]

Time series have broad usage in the wireless Internet of Things. This article proposes a nonlinear time series prediction algorithm based on the Small-World Scale-Free Network after the AIC-Optimized Subtractive Clustering Algorithm (AIC-DSCA-SSNET, AD-SSNET) to predict the nonlinear and unstable time series, which improves the prediction accuracy. The AD-SSNET is introduced as a reservoir based on the echo state network to improve the predictive capability of nonlinear time series, and combined with artificial intelligence method to construct the prediction model training samples. First, the optimal clustering scheme of randomly distributed neurons in the network is adaptively obtained by the AIC-DSCA, then the AD-SSNET is constructed according to the intra-cluster priority connection algorithm. Finally, the reservoir synaptic matrix is calculated according to the synaptic information. Experimental results show that the proposed nonlinear time series prediction algorithm extends the feasible range of spectral radii of the reservoir, improves the prediction accuracy of nonlinear time series, and has great significance to time series analysis in the era of wireless Internet of Things. [ABSTRACT FROM AUTHOR]

An analytical method for calculating the no-load magnetic field of external rotor permanent magnet brushless direct current motor (PMBLDCM) used as in-wheel motor of electric vehicle in the stator static coordinate and the rotor motion coordinate is presented in this paper. First, the analytic formulas of slotless permanent magnetic field in both coordinate systems are derived, respectively. Then, the complex relative permeance of external rotor PMBLDCM in both coordinate systems is calculated. Finally, the analytical solution of the no-load magnetic field in both coordinate systems is derived by applying the magnetic potential multiplied by the complex relative permeance. In this paper, a 46-pole-51-slot external rotor PMBLDCM is taken as an example, and the accuracy of the proposed analytical model is verified by the finite-element results. Based on the analytical model, the influences of the stator slotting effect on the no-load magnetic field of the external rotor and the inner stator are analyzed. The spatial order characteristics and frequency characteristics of the no-load magnetic field of the external rotor PMBLDCM in both coordinate systems are revealed, respectively. [ABSTRACT FROM AUTHOR]

In this study, Inconel 718 alloy samples were prepared by laser cladding deposition technology, and GCr15 steel balls were selected as the friction pair. The tangential fretting wear tests were conducted in ball-on-flat point contact mode using a self-developed multifunctional fretting wear tester. The damage evolution law of fretting damage with the number of cycles for laser cladding Inconel 718 alloy was investigated at room temperature (RT) and 400 °C. The obtained results reveal that the coefficient of friction curves and energy dissipation value in the process of fretting wear first increased, then decreased, and finally reached a stable state with increasing cycles. At room temperature, the fretting running states gradually changed from mixed slip regime (MSR) to gross slip regime (GSR). There was clear spalling in the fretting damage zone, and a large mass of wear debris was formed on the worn surface. As the test time continued, the width and depth of the wear marks gradually increased, the volume of material wear increased, and the wear damage of the material gradually aggravated. When the test temperature was 400 °C, the fretting was running in the MSR. As the number of cycles increased, spalling and adhesion of wear debris occurred in the fretting damage zone. The main mechanisms of fretting wear were oxidation wear, abrasive wear, fatigue wear and adhesive wear. [ABSTRACT FROM AUTHOR]

• The fretting wear mechanisms of Inconel 718 alloys deposited by laser cladding in different temperature were analyzed. • In PSR, the wear damage mainly shows elastic–plastic deformation, fatigue wear and abrasive wear. • In MFR and GSR, the wear damage was mainl combined with fatigue wear, peeling, adhesive wear and oxidative wear. • High temperatures induces oxidation reactions during friction and slow down the wear of the material. Fretting tests were performed on an Inconel 718 superalloy against GCr15 steel in a range of 25 ℃ < T < 400 ℃ to investigate the wear mechanism of the laser cladding-deposited Inconel 718 superalloy over a wide temperature range. The results show that when the displacement amplitude was 15 μm, the fretting was running in a partial slip regime (PSR), and the wear damage mainly showed elastic–plastic deformation, fatigue wear and abrasive wear. When the displacement amplitude increased to 100 μm, fretting occurred in a mixed slip regime (MSR) and gross slip regime (GSR). With continuous fretting wear, the dissipated energy of the material decreased gradually with increasing temperature in a stable state. The wear damage was mainly combined with fatigue wear and peeling. When the temperature was 100 ℃, the coefficient of friction (COF) value in the stable state was large. As the temperature increased, adhesive wear and oxidative wear gradually predominated in the fretting tests. The effect of high temperature easily formed an adhesive layer on the worn surface with wear reduction, especially at a high displacement amplitude. [ABSTRACT FROM AUTHOR]

Enterovirus 71 (EV71), the etiological agent of hand-foot-and-mouth disease, has increasingly become a public health challenge around the world. Previous studies reported that EV71 infection can induce autophagic machinery to enhance viral replication in vitro and in vivo, but did not address the underlying mechanisms. Increasing evidence suggests that autophagy, in a virus-specific manner, may function to degrade viruses or facilitate viral replication. In this study, we reported that EV71 infection of human epidermoid carcinoma (Hep2) and African green monkey kidney cells (Vero) induced autophagy, which is beneficial for viral replication. Our investigation of the mechanisms revealed that EV71 infection resulted in the reduction of cellular miR-30a, which led to the inhibition of Beclin-1, a key autophagy-promoting gene that plays important roles at the early phase of autophagosome formation. We provided further evidence that by modulating cellular miR-30a level through either overexpression or inhibition, one can inhibit or promote EV71 replication, respectively, through regulating autophagic activity. [ABSTRACT FROM AUTHOR]

Herpes simplex virus types 1 and 2 (HSV-1 and -2) are highly prevalent in many populations and therapeutic options are limited. Both viruses can establish latency by maintaining viral genomes in neurons of sensory ganglia. Primary or recurrent HSV infections may lead to deleterious outcomes: HSV-1 infection may result in corneal blindness and encephalitis and HSV-2 infection leads to herpes genitalis. While no effective vaccine is available, acyclovir is widely used for therapy, which targets and inhibits viral DNA polymerase. Although acyclovir is of low toxicity, resistant strains arise due to persistent use, mainly in immune compromised patients. In our effort to identify new HSV inhibitory molecules, harmine was found to potently inhibit HSV infection. Harmine, a beta-carbon alkaloid with an indole core structure and a pyridine ring, is widely distributed in plants. Earlier studies showed that harmine exhibited pharmacological activities such as antifungal, antimicrobial, antitumor, antiplasmodial and antioxidants. In the current study, we showed that harmine was a potent inhibitor of HSV-2 infection in vitro assays with EC 50 value at around 1.47 μM and CC 50 value at around 337.10 μM. The HSV RNA transcription, protein synthesis, and virus titers were reduced by the presence of harmine in a dose dependent manner. Further study on the mechanism of the anti-HSV activity showed that harmine blocked HSV-induced ROS production and the upregulated cytokine/chemokine expression, but our evidence showed that the inhibition of viral replication was unlikely mediated by the blocking of ROS production. We demonstrated that harmine significantly reduced HSV-2-induced NF-κB activation, as well as IκB-α degradation and p65 nuclear translocation. We found that harmine also inhibited HSV-2-mediated p38 kinase and c-Jun N-terminal kinases (JNK) phosphorylation. [ABSTRACT FROM AUTHOR]

Abstract: 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and polychlorinated biphenyls (PCBs) are persistent organic pollutants found as complex mixtures in the environment throughout the world. Therefore, humans are ubiquitously and simultaneously exposed to TCDD and PCBs. TCDD and PCBs alone have been linked to atherosclerosis. However, the effects of interactions or synergism between TCDD and PCBs on atherogenesis are unknown. We investigated the possible enhanced atherogenesis by co-exposure to TCDD and PCBs and the potential mechanism(s) involved in this enhancement. Male ApoE−/− mice were exposed to TCDD (15μg/kg) and Aroclor1254 (55mg/kg, a representative mixture of PCBs) alone or in combination by intraperitoneal injection four times over six weeks of duration. Our results showed that mice exposed to TCDD alone, but not Aroclor1254 alone, developed atherosclerotic lesions. Moreover, we found that atherosclerotic disease was exacerbated to the greatest extent in mice co-exposed to TCDD and Aroclor1254. The enhanced lesions correlated with several pro-atherogenic changes, including a marked increase in the accumulation of the platelet-derived chemokine PF4, and the expression of the proinflammatory cytokine MCP-1 and the critical immunity gene-RIG-I. Our data demonstrated that co-exposure to TCDD and Aroclor1254 markedly enhanced atherogenesis in ApoE−/− mice. Significantly, our observations suggest that combined exposure to TCDD and PCBs may be a greater cardiovascular health risk than previously anticipated from individual studies. [Copyright &y& Elsevier]

Highlights: [•] Protection of Se-Car on hepatic toxicity induced by MC-LR examined in mice. [•] Potential mitochondrial dysfunction and endoplasmic reticulum stress were disclosed. [•] Se-Car firstly confers protection against damages induced by MC-LR. [ABSTRACT FROM AUTHOR]

Abstract: Tetrachlorohydroquinone (TCHQ) is a major toxic metabolite of the widely used wood preservative, pentachlorophenol (PCP), and it has also been implicated in PCP genotoxicity. However, the underlying mechanisms of genotoxicity and mutagenesis induced by TCHQ remain unclear. In this study, we examined the genotoxicity of TCHQ by using comet assays to detect DNA breakage and formation of TCHQ-DNA adducts. Then, we further verified the levels of mutagenesis by using the pSP189 shuttle vector in A549 human lung carcinoma cells. We demonstrated that TCHQ causes significant genotoxicity by inducing DNA breakage and forming DNA adducts. Additionally, DNA sequence analysis of the TCHQ-induced mutations revealed that 85.36% were single base substitutions, 9.76% were single base insertions, and 4.88% were large fragment deletions. More than 80% of the base substitutions occurred at G:C base pairs, and the mutations were G:C to C:G, G:C to T:A or G:C to A:T transversions and transitions. The most common types of mutations in A549 cells were G:C to A:T (37.14%) and A:T to C:G transitions (14.29%) and G:C to C:G (34.29%) and G:C to T:A (11.43%) transversions. We identified hotspots at nucleotides 129, 141, and 155 in the supF gene of plasmid pSP189. These mutation hotspots accounted for 63% of all single base substitutions. We conclude that TCHQ induces sequence-specific DNA mutations at high frequencies. Therefore, the safety of using this product would be carefully examined. [Copyright &y& Elsevier]