Evaluation of Three-Dimensional Surface Roughness in Microgroove Based on Bidimensional Empirical Mode Decomposition.

Micromilling is an extremely important advanced manufacturing technology in the micromanufacturing industry. Compared with the traditional milling process, micromilling has stricter requirements on the surface roughness of the workpiece, and the roughness of the microcurved surface is not easy to measure. In order to more accurately characterize the curved surface morphology of the microgrooves obtained by micromilling, this paper proposes a method to extract the reference plane of the curved surface based on the bidimensional empirical mode decomposition algorithm and characterize the three-dimensional surface roughness of the curved surface. First, we synthesize the morphologies of the microgrooves by simulated non-Gaussian rough surfaces and models of textures. Second, the bidimensional empirical mode decomposition algorithm was used to extract the reference planes of the simulated microgrooves. Third, the three-dimensional roughness parameters suitable for the curved surfaces of microgrooves were selected to establish an evaluation system. The results show that the mean squared errors of the reference planes are below 1%, so bidimensional empirical mode decomposition can effectively extract reference planes, and the evaluation system of three-dimensional surface roughness proposed in this paper reflects morphological characteristics of the curved surfaces of microgrooves more thoroughly than that of two-dimensional surface roughness parameters.

Laser-Induced Slippery Liquid-Infused Surfaces with Anticorrosion and Wear Resistance Properties on Aluminum Alloy Substrates.

Slippery liquid-infused surfaces (SLISs) are developed as a potential alternative to superhydrophobic surfaces (SHSs) to resolve the issues of poor durability in corrosion protection and wear resistance. In this work, we used a simple laser processing technology to prepare a SLIS on the aluminum alloy (7075) surface. The superhydrophobicities of the modified surface and the oil film formed by liquid injection make the corrosive medium difficult to directly contact the surface and thus have a significant effect on corrosion resistance. The water and oil repellent SLIS exhibits durable corrosion resistance and excellent tribological properties compared with the SHS. The anticorrosion and wear resistance performances provided by the composite film have been assessed by multiple methods including the electrochemical test, immersion test, and friction wear test. The results indicate that compared to the bare surface, laser-ablated surface (LAS), and fluoroalkyl silane-modified SHS, the SLIS composite coating has better corrosion resistance and wear resistance, which is of great significance to expand the potential applications of 7075 aluminum alloys. The work provides a research basis for expanding the practical application of SLISs in complex environments.

Preparation of Micro-Pit-Textured PCD Tools and Micro-Turning Experiment on SiCp/Al Composites.

Serious tool wear occurs very often during machining due to the reinforcing phases in the workpiece. In this study, micro-pit-textures were prepared on the surfaces of PCD tools with a nanosecond laser to improve their cutting performance on SiCp/Al composites. The micro-pits were designed with rounded corners to improve the chip flow. The location and size of the texture were determined by analyzing the tool-chip contact area of the non-textured tool. The cutting performance of these textured PCD tools was investigated through orthogonal cutting experiments. It was found that the optimal cutting performance of the textured tools was achieved with the proper distance of the texture from the main cutting edge (35 µm) and the pit spacing (60 µm), aa a result of which the main cutting force reduced by about 14%, and the tool wear and surface adhesion significantly reduced. This texture was then applied in the micro-turning experiments of the PCD tool on the SiCp/Al composites. The cutting force in this experiment reduced by 22%, and the textured tool provided better chip transfer and tool anti-tipping. In this study, the role of SiC particles as a third body between the tool and the chip surface is discussed.

Regulated Li2 S Deposition toward Rapid Kinetics Li-S Batteries by a Separator Modified by CeO2 -Decorated Porous Carbon Nanostructure.

Although the high-energy-density lithium sulfur (Li-S) battery has been considered one of the most promising next-generation energy storage technology, the practical applications have been plagued by the sluggish reaction kinetics and the shuttle effect of lithium polysulfides intermediates. Here, to address the above issues, the authors report a novel separator modified by CeO2 -decorated porous carbon nanostructure (CeO2 /KB/PP). Benefiting from the strong polar surface and large specific surface area, (CeO2 -doped Ketjen Black) delivers efficient chemical adsorption toward lithium polysulfides. Moreover, rich oxygen vacancies of CeO2 provide abundant active sites to expedite lithium polysulfides conversion and regulate deposition and nucleation of Li2 S. Taking advantage of these merits, the battery with the CeO2 /KB/PP separator exhibits remarkable electrochemical performance, including low-capacity decay of only 0.06% per cycle over 1000 cycles at 2 C and superior rate capability of 627 mAh g-1 at 3 C. Even with a high sulfur loading of 6.6 mg cm-2 , the battery can achieve a high areal capacity of 3.6 mAh cm-2 after 100 cycles. This work provides a new application of rare-earth-based materials to facilitate Li-S batteries.

Study on In-Situ Tool Wear Detection during Micro End Milling Based on Machine Vision.

Most in situ tool wear monitoring methods during micro end milling rely on signals captured from the machining process to evaluate tool wear behavior; accurate positioning in the tool wear region and direct measurement of the level of wear are difficult to achieve. In this paper, an in situ monitoring system based on machine vision is designed and established to monitor tool wear behavior in micro end milling of titanium alloy Ti6Al4V. Meanwhile, types of tool wear zones during micro end milling are discussed and analyzed to obtain indicators for evaluating wear behavior. Aiming to measure such indicators, this study proposes image processing algorithms. Furthermore, the accuracy and reliability of these algorithms are verified by processing the template image of tool wear gathered during the experiment. Finally, a micro end milling experiment is performed with the verified micro end milling tool and the main wear type of the tool is understood via in-situ tool wear detection. Analyzing the measurement results of evaluation indicators of wear behavior shows the relationship between the level of wear and varying cutting time; it also gives the main influencing reasons that cause the change in each wear evaluation indicator.

A novel battery separator coated by a europium oxide/carbon nanocomposite enhances the performance of lithium sulfur batteries.

Lithium sulfur (Li-S) batteries represent one of the most promising future power batteries due to their remarkable advantages of low cost and ultrahigh theoretical energy density. However, the commercial applications of Li-S batteries have long been plagued by the shuttling effect of polysulfides and sluggish redox kinetics of these species. Herein, we designed a novel battery separator coated by a europium oxide-doped porous Ketjen Black (Eu2O3/KB) and tested its performance for the Li-S batteries for the first time. Experimental results and theoretical calculations reveal that the improved electrochemical performance can be attributed to the presence of Eu2O3. The strong binding effect between Eu2O3 and polysulfides is demonstrated in two aspects: (1) there exist strong interactions between Eu2O3 as a Lewis acid and polysulfides of strong Lewis basicity; (2) Eu2O3 with oxygen-vacancy defects provides active sites for catalyzing polysulfide conversion and polysulfide trapping. Thus, a Li-S battery with the Eu2O3/KB modified separator delivers highly stable cycling performance and excellent rate capability, with the capacity decay ratio of merely 0.05% per cycle under 1 C rate during 500 cycles, and high specific capacity of 563 mAh g-1 at 3 C rate. This work offers a meaningful exploration of the application of rare earth oxides for the modification of the separator towards high performance Li-S batteries.

P4HA1 regulates human colorectal cancer cells through HIF1α-mediated Wnt signaling.

Colorectal cancer (CRC) is the third most commonly diagnosed malignancy that is associated with high levels of mortality. CRCs are often associated with an aberrant wingless-type mouse mammary tumor virus integration site family (Wnt) signaling pathway known to be responsible for tumorigenesis and cancer progression. Other factors that contribute to CRC pathology include hypoxia, extracellular matrix and cellular microenvironment. In the present study, modulation of Wnt, a common molecular progenitor for CRC-associated pathology was evaluated. CRC tissues and specific cell lines were found to exhibit increased expression levels of prolyl 4-hydroxylase subunit α1 (P4HA1). P4HA1 expression was found to stabilize hypoxia inducible factor-1α (HIF1α). The silencing of P4HA1 resulted in decreased cell proliferation, cell cycle arrest in the G1 phase, decreased tumorsphere formation, decreased tumorsphere volume, increased susceptibility to 5-fluorouracil and increased caspase-3 activity. However, P4HA1 silencing resulted in the activation and thus proteasomal degradation of ß-catenin, indicative of the abrogation of Wnt signaling pathway. Wnt is a critical signaling pathway and is activated in most CRCs. HIF1α is a poor prognostic marker in CRC. The present study provided preliminary evidence that HIF1α and the Wnt signaling pathway in CRC are modulated through P4HA1. P4HA1 may serve not just as a biomarker for CRC prognosis but may also be targeted for potential therapeutic intervention.

Bio-Inspired Design of Bi/Tridirectionally Anisotropic Sliding Superhydrophobic Titanium Alloy Surfaces.

Many biological surfaces with the multi-scale microstructure show obvious anisotropic wetting characteristics, which have many potential applications in microfluidic systems, biomedicine, and biological excitation systems. However, it is still a challenge to accurately prepare a metal microstructured surface with multidirectional anisotropy using a simple but effective method. In this paper, inspired by the microstructures of rice leaves and butterfly wings, wire electrical discharge machining was used to build dual-level (submillimeter/micrometer) periodic groove structures on the surface of titanium alloy, and then a nanometer structure was obtained after alkali-hydrothermal reaction, forming a three-level (submillimeter/micrometer/nanometer) structure. The surface shows the obvious difference of bidirectional superhydrophobic and tridirectional anisotropic sliding after modification, and the special wettability is easily adjusted by changing the spacing and angle of the inclined groove. In addition, the results indicate that the ability of water droplets to spread along parallel and perpendicular directions on the submillimeter groove structure and the different resistances generated by the inclined groove surface are the main reasons for the multi-anisotropic wettability. The research gives insights into the potential applications of metal materials with multidirectional anisotropic wetting properties.

Transcription box­3 protects human umbilical vein endothelial cells in a high­glucose environment through sirtuin 1/AKT signaling.

The increasing burden of diabetes in low and middle­income countries is attributable to both genetic and epigenetic factors. Environmental­ and lifestyle­associated changes are also considered to be important contributors to this disease. The resultant co­morbidities arising from micro­and macrovascular changes in diabetes are difficult to manage and are an economic burden. However, very little is known about the molecular mechanisms that drive this phenotype. The present study aimed to investigate the role of sirtuin 1 (SIRT1)­ and transcription box­3 (TBX­3)­mediated regulation of endothelial dysfunction, given the significance of SIRT1 in glucose metabolism and the role of TBX­3 in the maintenance of cellular proliferation, senescence and apoptosis. Following the recruitment of adult patients with and without diabetes, both SIRT1 and TBX­3 expression was confirmed to be present in the sera of the patients with diabetes and the patients without diabetes; however, both SIRT1 and TBX­3 expression levels were higher in the sera of the patients with diabetes. Human umbilical vein endothelial cells (HUVECs) were further used for in vitro studies. Using TBX­3 and SIRT1 knockdown models, the cellular responses to proliferation, migration, invasion and tube formation were investigated using an MTS, cell cycle analysis, wound healing, Transwell and tube formation assay, respectively. Western blotting was also used to determine the downstream signaling pathways involved. The genetic knockdown of TBX­3 in hyperglycemic conditions significantly decreased the cellular proliferation, migration, invasion and angiogenesis of HUVECs. It was subsequently identified that TBX­3 mediated its effects through the activation of AKT and vascular endothelial growth factor (VEGF) signaling. However, the genetic knockdown of SIRT1 in the presence of TBX­3 overexpression and glucose failed to activate the AKT and VEGF signaling pathways. In conclusion, the results of the present study suggested that SIRT1 may positively regulate TBX­3 in endothelial cells, therefore, SIRT1 and/or TBX­3 may serve as potential novel biomarkers for disease progression.

Bioinspired Reversible Switch between Underwater Superoleophobicity/Superaerophobicity and Oleophilicity/Aerophilicity and Improved Antireflective Property on the Nanosecond Laser-Ablated Superhydrophobic Titanium Surfaces.

In this work, the bioinspired reversible switch between underwater superoleophobicity/superaerophobicity and oleophilicity/aerophilicity and improved antireflective property were successfully demonstrated on the nanosecond laser-structured titanium surfaces. Titanium materials were first transformed to be superhydrophobic after nanosecond laser ablation and low-temperature annealing treatments, showing oleophilicity/aerophilicity in water. If the surfaces were prewetted with absolute ethanol and then immersed into water, the surfaces showed superoleophobicity/superaerophobicity. More importantly, the underwater oleophilicity/aerophilicity of the surfaces could be easily recovered by natural drying, and the switch between the underwater superoleophobicity/superaerophobicity and oleophilicity/aerophilicity could be repeated many cycles. Moreover, based on the original antireflective performance of the surface of the laser-ablated micro/nanoscale structures, we demonstrated that the inspired improved antireflective property could be skillfully realized by the prewetting treatment. The developed bioinspired multifunctional materials provide a versatile platform for the potential applications, such as controlling oil droplets, bubbles, and optical behavior.

Blood coagulation dynamic testing sensor based on electromagnetic vibration.

Rapid detection techniques and methods of blood coagulation have attracted wide attention in academia and the business community in the presence of the increased demands for rapid assessment (point-of-care testing) of patients from surgery, intensive care unit, and other departments. The differential equation of vibration system composed of elastic support and electromagnetic induction devices was set up using the principle of damping vibration and establishing the dynamics model; meanwhile, the harmonic response analysis and vibration fatigue coupling analysis were carried out, the analysis results were optimized, and the experimental device of the electromagnetic induction testing sensor was established. In addition, the experimental device with blood coagulation reagent was assorted to establish the standard point-of-care testing rapid blood coagulation detection curve, and to compare the testing curve with that of the imported point-of-care testing blood coagulation instrument. The results showed that the first-order natural frequency of the designed sensor was 102.35 Hz, the correlation between the designed sensor and the imported equipment was 0.996, and the testing repeatability of the designed sensor could reach 0.002. Therefore, the designed blood coagulation testing sensor based on electromagnetic induction had the characteristics of favorable elasticity and anti-fatigue, which could meet the accuracy requirements of clinical detection. Taken together, this study could provide the core technology for developing the point-of-care testing instrument for blood coagulation dynamic testing.

Nanosecond Laser-Induced Underwater Superoleophobic and Underoil Superhydrophobic Mesh for Oil/Water Separation.

Materials with special wettability have drawn considerable attention especially in the practical application for the separation and recovery of the oily wastewater, whereas there still remain challenges of the high-cost materials, significant time, and complicated production equipment. Here, a simple method to fabricate the underwater superoleophobic and underoil superhydrophobic brass mesh via the nanosecond laser ablation is reported for the first time, which provided the micro-/nanoscale hierarchical structures. This mesh is superhydrophilic and superoleophilic in air but superoleophobic under water and superhydrophobic under oil. On the basis of the special wettability of the as-fabricated mesh, we demonstrate a proof of the light or heavy oil/water separation, and the excellent separation efficiencies (>96%) and the superior water/oil breakthrough pressure coupled with the high water/oil flux are achieved. Moreover, the nanosecond laser technique is simple and economical, and it is advisable for the large-area and mass fabrication of the underwater superoleophobic and underoil superhydrophobic mesh in the large-scale oil/water separation.

Electromagnetic induction sensor for dynamic testing of coagulation process.

With the increasing demand for coagulation POCT for patients in the surgery department or the ICU, rapid coagulation testing techniques and methods have drawn widespread attention from scholars and businessmen. This paper proposes the use of electromagnetic induction sensor probe for detection of dynamic process causing changes in the blood viscosity and density before and after coagulation based on the damped vibration principle, in order to evaluate the coagulation status. Utilizing the dynamic principle, the differential equation of vibration system comprising elastic support and electromagnetic induction device is established through sensor dynamic modeling. The structural parameters of elastic support are optimized, and the circular sheet spring is designed. Furthermore, harmonic response analysis and vibration fatigue coupling analysis are performed on the elastic support of the sensor by considering the natural frequency of the system, and the electromagnetic induction sensor testing device is set up. Using the device and coagulation reagent, the standard curve for coagulation POCT is plotted, and the blood sample application in clinical patients is established, which are methodologically compared with the imported POCT coagulation analyzer. The results show that the sensor designed in this paper has a first-order natural frequency of 11.368 Hz, which can withstand 5.295 × 102 million times of compressions and rebounds. Its correlation with the results of SONOCLOT analyzer reaches 0.996, and the reproducibility 0.002. The electromagnetic induction coagulation testing sensor designed has good elasticity and anti-fatigue, which can meet the accuracy requirement of clinical detection. This study provides the core technology for developing the electromagnetic induction POCT instrument for dynamic testing of coagulation process.

Direct Adsorption of Anti-CD34 Antibodies on the Nano-Porous Stent Surface to Enhance Endothelialization.

BACKGROUND: In-stent restenosis following the insertion of conventional drug-eluting stent has become an extremely serious problem due to coating techniques, with polymer matrices used to bind biological ingredients to the stent surface. However, several studies have indicated that new pro-healing technique could prevent stent thrombosis that can be caused by conventional drug-eluting stents. METHODS: A novel method of attaching anti-CD34 antibodies directly on the porous surface of a 316L stainless steel bare metal stent was developed in this study, which achieved both high stability of attached anti-CD34 antibodies on the metal stent surface and high antibody activity for stem cell capture. RESULTS: The in vitro and in vivo experimental results indicated that the new stent with directly coupled anti-CD34 antibodies can efficiently enhance stent endothelialization. CONCLUSIONS: This study indicates that we have developed a unique method of attaching anti-CD34 antibodies directly on the porous surface of a 316L stainless steel bare metal stent, which provides a novel polymer-free approach for developing pro-healing stents.

MicroRNA-577 inhibits gastric cancer growth by targeting E2F transcription factor 3.

The incidence and mortality rates of gastric cancer are one of the highest of all types of cancers. Emerging evidence has demonstrated that altered expression of micro (mi)RNAs may be implicated in the tumorigenesis of numerous types of cancer. Therefore, miRNAs may have potential as important tools in cancer diagnostics and therapeutics. miRNAs regulate the expression of genes involved in mediating cell proliferation and developmental timing, among numerous other processes. Altered expression levels of miRNAs may result in the ability of cells to proliferate aberrantly and migrate. The present study used reverse transcription-quantitative polymerase chain reaction assays to analyze miRNA-577 expression in gastric cancer tissues and cell lines, MTT and cell cycle analysis to examine cell proliferation in vitro, and luciferase assays and western blot to investigate miRNA-577's downstream targets. The results demonstrated that miRNA-577 was significantly downregulated in gastric cancer patient samples and cell lines. In addition, miRNA-577 affected an important regulator of E2F transcription factor 3 expression and that altered miRNA-577 expression resulted in the aberrant proliferation of gastric cancer cells.

The role of noggin in regulation of high glucose-induced apoptosis and insulin secretion in INS-1 rat beta cells.

OBJECTIVES: The purpose of this study was to investigate the effects of Noggin on high glucose-induced apoptosis and insulin secretion in pancreatic beta cells. MATERIALS AND METHODS: Different concentrations of glucose were used to examine their effects on INS-1 rat beta cells in vitro. When specific siRNA targeting Noggin and recombinant Noggin were added, apoptosis and insulin secretion were measured, respectively to determine their effects in INS-1 cells. RESULTS: Glucose stimulated the expression of Noggin in a dose-dependent manner. Knockdown of Noggin further increased apoptosis and reduced insulin secretion when INS-1 cells were exposed to high glucose. Conversely, administration of recombinant Noggin significantly reduced apoptotic cell number, and promoted insulin secretion. Finally, treatment with inhibitor of Smad phosphorylation exerted similar effects on cell apoptosis and insulin production to Noggin administration in glucose-treated INS-1 cells. CONCLUSION: Our findings indicate that Noggin inhibits apoptosis and promotes insulin secretion in pancreatic beta cells through the inhibition of Smad signaling. Gene therapy of delivering Noggin may facilitate the treatment for patients with type 2 diabetes mellitus.

Accelerated endothelialization with a polymer-free sirolimus-eluting antibody-coated stent.

Drug-eluting stents have shown an impressive reduction of in-stent restenosis for many years. However, stent thrombosis due to incomplete/late endothelialization has raised major safety concerns. To overcome these problems, we developed for the first time a polymer-free sirolimus-eluting antibody-coated stent (PFSEACS) by combining polymer free and endothelial progenitor cell-capture pro-healing approaches. In the first phase, the stents were prepared by loading sirolimus on the porous outer stent surface and directly fixing the anti-CD34 antibodies without any medium carriers on the blood contacting surface. The dose and elution of sirolimus, the amount and stability of anti-CD34 antibody immobilization, and the rate of CD34+ cell capture were evaluated. In the second phase, the stents were validated in an animal model of coronary arteries in pigs. The stent was observed to start collecting endothelial progenitor cells ~2 h after stent implantation and exhibited greatly enhanced endothelialization while maintaining an excellent anti-restenosis activity comparable to the polymer-free sirolimus-eluting stents. Overall, both in vitro and in vivo evaluations indicated that novel PFSEACSs exhibited facilitated endothelialization with excellent anti-restenosis activity and thus should merit further clinical studies.

The union of anti-CD34 antibody can improve the performance of drug-eluting stents.

OBJECTIVES: The authors investigate whether the combination of anti-CD34 antibody with DES is win-win cooperation. BACKGROUND: DES may reduce the risk of restenosis compared to bare-metal stents (BMS), but they were found to inhibit the healing process of intima. METHODS: Fifteen BMS, 17 DES, and 16 combined anti-CD34 antibody and DES were randomly implanted in the coronary arteries of 22 minipigs. Ten minipigs were followed up to 2 weeks. The stenting coronary segments were examined by histological examination and scanning electron microscopy after in vivo coronary angiography and intracoronary optical coherence tomography (OCT) examinations. The other 12 minipigs were followed up to 3 months. Coronary angiography and intracoronary OCT examination were performed in vivo and histological examination was performed on the stenting coronary segments. RESULTS: After 2 weeks, the neointimal covering level of the DES was lower than that in BMS, but the covering level of the combined stents was even better than the BMS. After 3 months, neointimal hyperplasia was significant in the BMS, but not in the other two types of stents. The in-stent late lumen loss of the combined stents even showed a decreasing tendency when compared with the DES. CONCLUSION: The combination of anti-CD34 antibody and DES can not only well offset the short-term inhibitory effect on re-endothelialization but also slightly enhance the long-term antiproliferative effect.

[Monitoring early toxicity of heavy metals including Hg using a HSE-SEAP reporter gene].

OBJECTIVE: To develop a cellular assay based on heat shock signal pathway and secreted alkaline phosphatase (SEAP) reporter gene for investigating/predicting the early toxicity of heavy metals on HeLa cells in Chinese traditional medicine (TCM). METHOD: The pHSE-SEAP plasmid was transfected into HeLa cells to build a HSE-SEAP-HeLa cell model. For validation of the model, the transfected cells were treated by either heating at 42 degrees C for 1 h or incubated with 5 mol x L(-1) CdCl2 for 4 h. Then the cells were covered in complete DMEM culture medium for 48 h and the activity of SEAP (reflecting the cellular level of heat shock protein) in cultural supernatants was measured; meanwhile, cell viability was determined by MTT assays. In addition, the cells were treated by four mercury compounds, HgCl2, merthilate sodium, HgS and cinnabar at the sub-lethal concentrations (determined by MTT assays). Then the heat shock response was detected likewise. RESULT: Significant level of secreted alkaline phosphatase (SEAP) was found in pHSE-SEAP transfected HeLa cells treated either by heating (42 degrees C) or incubating with CdCl2. The heat shock protein was induced by CdCl2 before decrease of cell viability was observed. All four mercury compounds induced heat shock response in both time and concentration-dependant manner. However, there were big differences among the mercury compounds, suggesting potential differences for early-stage toxicity in vivo. CONCLUSION: The pHSE-SEAP transfected HeLa cells respond effectively to heat shock and metal stresses, and therefore provide a practical and repeatable assay for investigating/predicting the early toxicity of heavy metals and mineral-containing drugs in TCM.

Metal ions induced heat shock protein response by elevating superoxide anion level in HeLa cells transformed by HSE-SEAP reporter gene.

The aim of this work is to define the relationship between heat shock protein (HSP) and reactive oxygen species (ROS) in the cells exposed to different concentrations of metal ions, and to evaluate a new method for tracing the dynamic levels of cellular reactive oxygen species using a HSE-SEAP reporter gene. The expression of heat shock protein was measured using a secreted alkaline phosphatase (SEAP) reporter gene transformed into HeLa cell strain, the levels of superoxide anion (O(2)(-)) and hydrogen peroxide (H(2)O(2)) were determined by NBT reduction assay and DCFH staining flow cytometry (FCM), respectively. The experimental results demonstrated that the expression of heat shock protein induced by metal ions was linearly related to the cellular superoxide anion level before cytotoxic effects were observed, but not related to the cellular hydrogen peroxide level. The experimental results suggested that metal ions might induce heat shock protein by elevating cellular superoxide anion level, and thus the expression of heat shock protein indicated by the HSE-SEAP reporter gene can be an effective model for monitoring the dynamic level of superoxide anion and early metal-induced oxidative stress/cytotoxicity.