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Entropy-stabilized Oxides (ESOs) composed of multiple cations have drawn extensive research interest in recent years due to their distinctive structural characteristics and interesting functional properties induced by entropy engineering. In this work, the first multi-component CoMnFeZnYO7 thermistor material for temperature sensing applications was synthesized via the solid-state reaction route in pursuit of higher long-term stability. The as-prepared oxide contains an intriguing dual-phase structure of cubic spinel and ortho-perovskite, and simultaneously each cation is highly homogeneously dispersed on the microscopic scale. This two-phase multi-component oxide exhibits ultra-high stability (ΔR/R0 = 0.073%) under accelerated aging conditions of 125 °C for 500 h. The successful fabrication of such multi-component oxides with ultra-high stability brings an innovative perspective to the design and application of electronic materials.

The center of this work is to interpret the role of particle sizes of starting oxides on the properties of spinel-type Mn1.1Co1.5Fe0.4O4 negative temperature coefficient ceramics. Investigations were conducted using the traditional solid-state reaction route. The optimized microstructure of Mn1.1Co1.5Fe0.4O4 ceramics was achieved by utilizing the appropriate proportion of micron- and nano-sized particles. Distortion of the [MnO6] octahedron and the effects of grain sizes generate significant changes in resistivity while without inducing many changes in the B-25/50 value (3700 K). Aging analysis indicates that the use of nano-sized particles deteriorates the stability of Mn1.1Co1.5Fe0.4O4 ceramics, i.e., the Delta R/R-0 hugely increases from 0.5% to 15.1% after accelerated aging at 200 degrees C for 800 h. This work will provide clear guidance for the selection of raw materials from the actual research to the production process.

Dense Mn1.1Co1.5Fe0.4O4 ceramics are successfully synthesized by using micron- and nano-sized particles as raw materials in a solid-state reaction method. The results show that the grain sizes of the as-sintered ceramics decreased with the increasing amounts of nano-sized particles. Interestingly, the grain surface presents concave flakes when all nano-sized particles are used. In particular, the resistance of the grain boundaries and the migration of oxygen vacancies increased the resistivity and aging coefficient, respectively. This study indicates that it's a useful approach to modulate the structural and electrical properties by using the different particle sizes of raw materials.

Low-temperature NTC (Negative temperature coefficient) thermal ceramic material Mn0.6Ni0.9Co1.5−xLixO4–LiF was synthesized by chemical co-precipitation method and prepared by fast and efficient liquid phase sintering (1000 °C, 5 min). X-ray diffraction analysis results show that the addition of sintering aid LiF does not introduce an impurity phase, and 7%LiF-Mn0.6Ni0.9Co1.5−xLixO4 (x ≥ 0.2) only shows a single-phase spinel -phase MnCo2O4 (PDF# 23-1237). The morphology of the microstructure is analyzed by SEM, and the size of LiF-added grains increases significantly. SEM shows that the density becomes higher, and the electrical properties reflect the trend of the overall lower resistivity and confirm increasing density. The grain size of Mn0.6Ni0.9Co1.5−xLixO4-2%LiF increased from 0.89 to 2.14 µm. In addition, the density of the 4%LiF-Mn0.6Ni0.9Co1.1Li0.4O4 sample reached 4.27g·cm−3. Raman spectroscopy explained the Raman vibration peaks of LiMn2O4 and MnCo2O4. The temperature-sensitive material has obvious NTC performance in the temperature range of − 50 °C to 110 °C. A good linear relationship between lnρ and 1000/T exists over the measured temperature region, which is the characteristic of the small-polaron hopping transport. Mn0.6Ni0.9Co1.5−xLixO4-LiF thermosensitive materials are suitable for liquid phase sintering.

In this paper, negative temperature coefficient (NTC) thermistors Mn0.6Ni0.9Co1.5−xLixO4 (x = 0, 0.05, 0.1, 0.2) used for low temperature were synthesized by the co-precipitation method. XRD indicates the formation of single-phase LiMn2O4 spinel. SEM shows that the incorporation of lithium reduces the sintering activity and increases the grain size 2 to 6.8 μm. XPS presents that the remarkable change of the contents of Mn3+/Mn4+ and Co2+/Co3+ confirms the conduction mechanism of the variable ion transition. The relationship between the electrical resistivity and the temperature shows that the doping of Li benefits the Mn0.6Ni0.9Co1.5O4 material to increase the resistance value and reduce the material constant B value. This is significant because of traditional thermal-sensitive materials with high resistance and high B, while low-B high resistance materials have been scarcely reported. The materials are expected to be used for deep sea thermal detector.

Metallization of Negative Temperature Coefficient (NTC) thermistors deposited via direct current magnetron sputtering had been the main subject of this extensive research. A variety of multi-layered thin films, namely Pd (35 nm–1200nm)/Ag(400 nm), were utilized as a multilayer structure electrode materials. On the other hand, a conventional screen printing silver paste electrode was used for a comparative study. In general, the Pd/Ag experimental results had shown that the electrode had a good ohmic contact with ceramics. The resistance of electrodes using Pd/Ag was constantly lower than that of using traditional screen-printed electrodes (29.9–33.7

Mn1.1Co1.5Fe0.4O4 ceramics with tailored sintering temperature, microstructure, and NTCR characteristics were prepared using Bi2O3 sintering additive by a solid-state reaction route. Densification and morphological characterization indicate that bismuth trioxide can play a critical role in the sintering process. The results reveal that the sintering temperature can be decreased significantly from 1200 °C to 1050 °C by using the appropriate content of Bi2O3 additive. The resistivity decreases first and then increases with increasing Bi2O3 content. The obtained B25/50 value and ρ25 ranges were 3647–3697 K, and 800–1075 Ω cm, respectively. Oxygen sorption theory can be used to illustrate the optimal thermal stability (ΔR/R0 = 0.10%). Complex impedance analysis further elucidates that grain boundaries make a dominant contribution to the total resistance. The mechanisms of grain boundary conduction and relaxation behavior are systematically analyzed. These findings open up a window for the further advancement of NTC ceramics at lower sintering temperature.

Mn1.2Co1.5Ni0.3O4 ceramic chips with 90, 100, 110 and 120 µm thickness were developed using the tape casting method. The structure, electrical properties and thermal time constant have been investigated as a function of the thickness of the miniature NTC chip thermistors. The ρ25 increased from 127 to 449.7 Ω cm and the thermal constant B25/50 increased from 52.8 to 180.5 K as the thickness increased. This could be a result of the increased grain boundary resistance and Mn3+/Mn4+ ratio (0.7–1.02) from the increased thickness. The thermal time constants were 0.83, 0.89, 1.05 and 1.10 s for chip thermistors with thicknesses from 90 to 120 µm, respectively. This reveals that the thickness of chips could affect the thermal time constant, a result of significantly different dissipation constants and heat capacities in MCN thermistors. The proposed sensors demonstrated a superior temporal response.

Dense Mn1.1Co1.5Fe0.4O4 ceramics are successfully synthesized by using micron- and nano-sized particles as raw materials in a solid-state reaction method. The results show that the grain sizes of the as-sintered ceramics decreased with the increasing amounts of nano-sized particles. Interestingly, the grain surface presents concave flakes when all nano-sized particles are used. In particular, the resistance of the grain boundaries and the migration of oxygen vacancies increased the resistivity and aging coefficient, respectively. This study indicates that it's a useful approach to modulate the structural and electrical properties by using the different particle sizes of raw materials.

This paper presents the optimal atmosphere annealing conditions for Mn1.2Co1.5Ni0.3O4±δ ceramic thin films fabricated by the RF magnetron sputtering method. The microstructure and oxygen distribution, together with electrical properties, are combined and applied for determining thermal stability. All of the Mn1.2Co1.5Ni0.3O4±δ films, which are annealed at various oxygen atmosphere from 1 × 10−3 to 1 × 105 Pa, exhibit a negative temperature coefficient characteristic and show a poly-crystalline spinel structure. The film which annealed at 10 Pa with the most uniform and most dense surface morphology has the minimum resistivity compared to the others. It is characterized by the highest Mn3+ and Mn4+ pair content, which gives the highest carrier concentration of ceramic films. Combined with the aging test at 125 °C for 500 h, the films annealed at 10 Pa have the minimum resistance drift (ΔR/R0 = 2.35%), which is mainly affected by the oxygen vacancy concentration. This demonstrates that the film thermistors annealed in a hypoxia state will never be stable. This is because there will be several oxidation reactions leading to a continuous generation of cationic vacancies during high temperature aging. The present results will open a way to design desired stable negative temperature coefficient thermistors by adjusting the annealing oxygen atmosphere of films.

A series of negative temperature coefficient (NTC) thick-film ceramics based on Co2.77Mn1.71Fe1.10Zn0.42O8 (CMFZ) were successful prepared using a slurry spin coating technique. The high density and stable B25/50 constant in the range of 3829–3862 K of CMFZ thick films were obtained. The feasibility of preparing CMFZ thick films by spin coating is proved. It is confirmed that the microstructure and electrical properties of films are sensitive to the solid content in pastes. A smoother and denser surface morphology and relatively high electrical stability is obtained in 70 wt% solid content with the resistance drift rate of 19.4%. The resistance drift rate of all samples is found to be less than 1% per 100 h after pre-aging at 125 °C for 400 h. Compared to the traditional screen-printing method, spin coating simplifies the process steps and reduces some variables that could affect the quality of the thick film. These results clearly indicate that the spin coating technique is a potential and competitive method in the production of NTC thick film ceramic.

In this paper, the Mn1.5 − xCo1.2Cu0.3ZnxO4 (0 ≤ x ≤ 0.5) negative temperature coefficient (NTC) ceramics were attained by the traditional solid state reaction method. The effects of Zn addition on microstructure and electrical properties were characterized by thermo-gravimetry–differential scanning calorimetry, X-ray diffraction, scanning electron microscope, electrical measurement and X-ray photoelectron spectroscopy analysis. It was found that the resistivity decreased slightly with increasing Zn ions content for x ≤ 0.2, but increased remarkably for higher Zn ions content. The values ρ25 and B25/50 of Mn1.5 − xCo1.2Cu0.3ZnxO4 (0 ≤ x ≤ 0.5) NTC thermistors were in the range of 126–706 Ω cm and 3323–3714 K, respectively. The values of relative resistance drift (ΔR/R0) were in the range of 2.7–1.13% and had a minimum value with the Zn content x = 0.5 after aging test at 125 °C for 500 h. This suggests that the electrical properties can be adjusted to desired values by controlling the Zn ion doping content. Most importantly, the stability of Mn1.5 − xCo1.2Cu0.3ZnxO4 ceramic can be effectively improved by Zn doping.

In this work, polycrystalline LaxBa1−xCoO3−δ (0 ≤ x ≤ 0.1) ceramic samples were prepared by conventional solid-state reaction process. La3+ doping effects on the crystal structures, densities, microstructures and thermosensitive characteristics of the LaxBa1−xCoO3−δ ceramics were investigated. The major phase presented in the sintered samples is a hexagonal perovskite BaCoO2.6 phase. The doping of La3+ reduces the quantity of voids and improves the densities of the LaxBa1−xCoO3−δ ceramics compared with La-free ceramic. The resistivities of the LaxBa1−xCoO3−δ ceramics decrease exponentially with increasing temperature in each of the range of 10–26 K and 26–100 K. The resistivities and B constants increase as the contents of La3+ increase in the LaxBa1−xCoO3−δ ceramics.

In this work, the effect of Fe addition on microstructure and electrical properties of Co1.5Mn1.5−xFexO4 (0.2 ≤ x ≤ 1.0) NTC thermistors was studied. The added Fe did not affect the crystalline structure and formed a single cubic spinel phases. The density of Co1.5Mn1.5−xFexO4 samples decreased significantly with increasing Fe content. The values of ρ25, ρ50, B25/50, and Ea of ceramic samples were in the range of 2283–14273 Ω cm, 730–5157 Ω cm, 3701–3991 K, and 0.3196–0.3445 eV, respectively. This means that the electrical properties can be adjusted to desired values, depending on Fe content. The values of relative resistance drift ΔR/R0 (0.2 ≤ x ≤ 1.0) had a minimum value when x = 0.4, after aging test for 500 h.

In the present work, BaCoO3−δ ceramic materials were prepared via conventional solid state reaction at different sintering temperatures. The crystal structures, microstructures and electrical properties of BaCoO3−δ ceramics were systematically investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and electrical measurement. The XRD patterns indicate that the major phases presented in the sintered samples are hexagonal perovskite BaCoO2.6 phase and some other minor phases (BaO or Co3O4). SEM images show that the grain size increases with temperature increasing. The resistivity of the prepared BaCoO3−δ ceramics thermistors decreases exponentially with increasing temperature in each of the range of 12.5–26 and 26–100 K. These prepared materials are intended to be used for NTC thermistors in a temperature range from 12.5 to 100 K.

Manganese-based spinel oxides (Mn1·1Co1·5Fe0·4O4) are gaining widespread attention due to their extensive applications in sensors and energy devices. A drawback is their high synthesis temperature and difficult regulation of electrical parameters. As a remedy, Bi2O3–ZnO dual-additives were used. Eventually, the Bi2O3–ZnO co-modified Mn1·1Co1·5Fe0·4O4 ceramics were successfully fabricated with a lower sintering temperature at 1060 °C. More importantly, the incorporation of Zn ions can effectively adjust the electrical properties of the Mn1·1Co1·5Fe0·4O4 ceramics, especially the resistivity and B constant. The resulting ρ25 and B25/50 were 880–1694 Ω cm and 3697–3989 K, respectively. The potential cation distributions and hopping conduction mechanism are clarified clearly in combination with X-ray photoelectron spectroscopy analysis.

Mn1.2Co0.6Ni1.2O4 negative temperature coefficient thermistor materials were prepared by the rheological phase reaction method. The effect of sintering temperature on the microstructure and electrical properties of Mn1.2Co0.6Ni1.2O4 ceramic materials was systemically investigated and characterized by XRD, SEM, and electrical measurement. The results indicate that all the ceramic materials show the single cubic spinel phase, as well as the material constant B values and ρ25 of the Mn1.2Co0.6Ni1.2O4 thermistors are in the range of 3199–3343 K, 593–1299 Ω cm, respectively, as the sintering temperature increases from 1100 to 1250 °C. At the sintering temperature of 1200 °C, the ceramic samples have the best thermal stability, that is the lowest resistivity drift rate (ΔR/R) of 0.43 %. Therefore, Mn1.2Co0.6Ni1.2O4 ceramic materials prepared by the rheological phase reaction method meet the demands of market development and have potential in the industrial applications.

Mn-Co-Ni-O nanoceramic microspheres with high density, uniformity, and size tunability are successfully fabricated using in situ ink-jet printing and two step sintering (TSS) techniques. The microspheres, synthesized by an effective and facile reverse microemulsion method, consist of uncalcined Mn-Co-Ni-O nanocrystallines that show a well formed single tetragonal spinel phase and an average particle size distribution of approximate to 20 nm. The sintering behavior, microstructure, and electrical properties of the Mn-Co-Ni-O nanoceramic microspheres are systematically investigated and characterized. The results indicate that the sintered Mn-Co-Ni-O nanoceramic microspheres show high density and improved electrical properties. The highest R-25, B-25/50, E-a, and alpha(25) values achieved at sintering temperature of 1150 degrees C are 4846.7 K Omega, 4320 K, 0.401 eV, and -5.24% K-1, respectively for these Mn-Co-Ni-O nanoceramic microspheres. Furthermore, the formation mechanism of uncalcined Mn-Co-Ni-O nanocrystallines and an analysis of the TSS procedure of the nanoceramic microspheres are discussed.

We report a simple and effective in situ inkjet printing method for the fabrication of nanostructured and highly dense Ni0.9Mn1.8Mg0.3O4 (NMM) spinel oxide nanoceramic microbeads materials. In our method, the ceramic inks are fabricated that single cubic spinel NMM nanocrystallines synthesized via co-precipitation method, disperse well in organic solution, and have shown perfect dispersibility and stability. After inkjet printing using these ceramic inks, NMM microbeads are sintered via two-step sintering (TSS) process at different temperatures. The sintering behavior, microstructure and electrical properties of NMM nanoceramic microbeads prepared via TSS process are investigated and characterized systematically. These results indicate that high performance of NMM microbeads with moderate resistance values (98 331–174 601 Ω), lower thermal time constant (58–147 ms), and higher material constant (4176–4309 K) are achieved by tuning the sintering temperatures.

Microstructure and electrical properties of Co2.77Mn1.71Fe1.10Zn0.42O8 (CMFZ) ceramics as a function of temperature were studied in the sintering process. The optimum sintering temperature of 1200 °C is determined to obtain the optimum microstructure and electrical properties. Both microstructure and electrical properties are sensitive to the different sintering temperatures. In particular, the appropriately increased sintering temperature enhances the densification and the homogeneity of grain size. However, the accelerated grain growth with a large number of closed pores appears when above the optimum sintering temperature. The electrical resistivity first increases and then decreases with the increased sintering temperatures. The ρ25 and B25/50 constant are in the range of 3072–4238 Ω cm and 4021–4056 K, respectively. X-ray photoelectron spectroscopy (XPS) was analyzed the evolution of resistivity clearly and proved the n-type semiconductor of CMFZ ceramics.

The high performance Mn1.2Co1.5Ni0.3O4 (MCN) ceramic materials are successfully fabricated using nanoparticles which are synthesized by the reverse microemulsion method. The morphology, crystal structure and particle size distribution of MCN nanoparticles are characterized by the XRD, SEM, TEM and HRTEM. The results show the well single tetragonal spinel structure and the narrow particle size distribution about 40 nm. As the sintering temperature increasing from 1000 to 1250 °C, all the MCN ceramic samples prepared by above-mentioned nanoparticles show the same single tetragonal spinel structure. The thermal sensitive properties with high values of ρ25, B25/100, Ea, and α25 of MCN ceramics at different sintering temperatures are in the range of 68,805–497,730 Ω cm, 4578–5159 K, 0.395–0.445 eV, and −5.2 to −5.8 %/K, respectively. These features indicate that the microstructure and electrical properties of MCN ceramics are relevant to the sintering temperature.

Mn-Co-Ni-O ultrafine ceramic nanoparticles are successfully synthesized by the reverse microemulsion method in a triton X-100/n-hexanol/cyclohexane system. The thermal decomposition process, crystallinity and crystal structure of Mn-Co-Ni-O powders are investigated and characterized by thermogravimetric-differential scanning calorimetry (TG/DSC), Fourier Transform Infrared (FT-IR), X-ray powders diffraction (XRD) and High Resolution Transmission Electron Microscope (HRTEM), respectively. The TGA/DSC, FT-IR and XRD results show that the reverse microemulsion method can effectively reduce the calcination temperature to 600 degrees C for synthesizing cubic spinel phase Mn-Co-Ni-O ceramic particles. Furthermore, the XRD and HRTEM images reveal that the particles are highly crystalline and have a narrow and uniform particle size distribution. These findings indicate that Mn-Co-Ni-O nanoparticles prepared via reverse microemulsion process meet demands for obtaining better microstructure and performance of Mn-Co-Ni-O materials.

Single (100)-oriented Mn1.56Co0.96Ni0.48O4 thin films were achieved on SrTiO3 (100) substrate using laser molecular beam epitaxy technique. The effects of growth temperature and oxygen partial pressure on crystal quality and negative temperature coefficient characteristics were studied by XRD, RHEED, AFM, SEM, resistance-temperature measurements and impedance spectrum. The results showed that the growth direction (400) of epitaxial Mn1.56Co0.96Ni0.48O4 thin films was parallel to SrTiO3 (100) substrate and the best NTC characteristic with B value of about 3000 K was found in the Mn1.56Co0.96Ni0.48O4 thin films grown at 500 degrees C with Po-2 = 5 x 10 (3) Pa for 3 h. Such thin films are desirable for a wide range of practical applications in the NTC thermistors. (C) 2014 Elsevier B. V. All rights reserved.

A new series of composite, negative temperature coefficient (NTC) ceramics based on the (aY2O3 + bCeO2)−0.4LaCr0.5Mn0.5O3 (a + b = 0.6) were carefully prepared and related electrical properties were investigated. All the NTC thermistors showed a linear relationship between the natural logarithm of the resistance and the reciprocal of the absolute temperature, indicative of NTC characteristics. The obtained B 25/85 constants were in range of 2,100–2,700 K. The magnitude order of the resistivity at 25 °C was of 103–109 Ωcm and activation energies varied from 0.185 to 0.231 eV. The aging coefficient of the NTC thermistors with CeO2 was less than 2 % for the time period of 900 h, suggesting that NTC thermistors with CeO2 possessed a better electrical stability in comparison with CeO2-free thermistors.

foundation of seed project of Urumqi Science and Technology Bureau K101410009; Natural Science Foundation of Xinjiang Uygur Autonomous Region 2010211A59

The effects of Sr-doping on Ni-Mn-Co-O spinel-structured NTC ceramics were investigated. And the precursors of Sr-doped NiCoMnO4 NTC ceramics were attained by solid state reactions at room temperature, with no intermediate compounds. Its formation and the structural evolutions were characterized by thermo-gravimetry-differential scanning calorimetry, X-ray diffraction and scanning electron microscopy with energy dispersive spectroscopy. Related electrical analyses were also performed. The values of R-298K, B-298/323 constant and the temperature coefficient of resistance alpha(298K) of the thermistors are in the range of 168-1,738 Omega, 3,257-3,359 K and -3.64 to -3.78 % K-1, respectively. Complex impedance analysis shows, for x = 0.2, single semicircular arc whose shape does not have any change with temperature. The grain boundary properties exhibit thermistor parameters with a negative temperature coefficient characteristic. The conduction for the grain boundary could be explained by oxygen vacancies. The results show that the ceramics exhibits a good electrical property because of narrow grain size distribution, controlled morphology, and high purity. This suggests that the electrical properties can be adjusted to desired values by controlling the Sr cation content. This series of materials could be considered as practical materials for NTC thermistor. Most importantly, this new approach greatly simplifies the preparation processes.

Two new sesquiterpene lactones, 1β,15-diacetoxy-5,7α,6,11β(H)-eudesm-3,4-en-6,12-olide (1) and 1β-hydroxy-3,4-en-15-O-β-glucopyranosyl-5,7α,6,11β(H)-eudesman-6,12-olide (2), were isolated from Sonchus arvensis L. (Asteraceae), together with ten known compounds. Their structures were elucidated through spectroscopic and chemical methods. All these known compounds except oleanolic acid (11) were isolated from the genus Sonchus for the first time. Selected new compounds were evaluated for antibacterial activity; unfortunately, they showed weak or no activities against Streptococcus mutans ATCC 25175.

A pure spinel-type phase was attained by solid state reactions at room temperature, with no intermediate compounds. Its formation and the structural evolutions have been characterized by thermogravimetry-differential scanning calorimetry (TG/DSC) tests, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Related electrical analyses were also performed. The results showed that the powders and ceramics prepared by the solid state reactions at room temperature exhibit a good electrical property because of narrow grain size distribution, controlled morphology, and high purity. Most importantly, this new approach greatly simplifies the preparation processes.

Ceramic compositions based on (aY2O3 + bCeO 2)-0.4YCr0.5Mn0.5O3 (a + b = 0.6) were prepared by conventional solid state reaction at 1200 dC, and sintered under air atmosphere at 1600 dC. For 0 l a l 0.6, XRD patterns have shown that the major phases presented in the calcined powders are Y 2O3, CeO2 and orthorhombic perovskite YCr 0.5Mn0.5O3 phase, respectively. SEM and EDAX observations confirm the YCr0.5Mn0.5O3 phases mostly exist at the grain, whereas the Y2O3 and CeO 2 phases mainly exist at the grain boundaries. Complex impedance analysis shows that, for 0 l a l 0.6, single semicircular arc whose shape does not show any change with temperature. Nevertheless, for a = 0, two overlapping semicircular arcs are observed at and above 300 dC. The grain boundary properties exhibit thermistor parameters with a negative temperature coefficient characteristic. The relaxation behavior and conduction for the grain boundary could be due to a space-charge relaxation mechanism and oxygen vacancies, respectively.

A computer program, QtUCP, has been developed based on several well-established algorithms using GCC 4.0 and Qt [registered trademark] 4.0 (Open Source Edition) under Debian GNU/Linux 4.0r0. It can determine the unit-cell parameters from an electron diffraction tilt series obtained from both double-tilt and rotation-tilt holders. In this approach, two or more primitive cells of the reciprocal lattice are determined from experimental data, in the meantime, the measurement errors of the tilt angles are checked and minimized. Subsequently, the derived primitive cells are converted into the reduced form and then transformed into the reduced direct primitive cell. Finally all the patterns are indexed and the least-squares refinement is employed to obtain the optimized results of the lattice parameters. Finally, two examples are given to show the application of the program, one is based on the experiment, the other is from the simulation.

Negative temperature coefficient (NTC) thermistors based on Ni 0.9 Mn 2.1-x Mg x O 4 (0&lex&le0.3) materials with different compositions were synthesized by a rheological phase reaction with ultrasound radiation (RPR-UR) method. It was found that the as-prepared powder crystallized well with spinel structure. It presented a microstructure of well-packed grains. The resistivity, B 25/50 constant and activation energy with a wide range of values were obtained. And it can be adjusted to desired values for industrial applications by controlling the MgO content. All the results suggest that the RPR-UR method is a promising technique for the preparation of Ni 0.9 Mn 2.1-x Mg x O 4 NTC ceramic materials.

Non-metastatic cells 5 (NME5), a recently found gene belonging to the NDPK-like molecules gene family, is highly expressed in testis and some types of human cancer. Current studies have revealed diverse potential functions of NME5 and we have reported that NME5 is associated with innate resistance to gemcitabine in human pancreatic cancer cells in previous study. However, the mechanism underlying the transcriptional regulation of NME5 has not been elucidated yet. In this study, we analyzed the 5′-flanking region of the human NME5 gene and revealed its transcription start site (TSS) at − 35 bp relative to its translation start codon ATG. Using 5′ unidirectional deletion analysis, we demonstrated that the proximal promoter of NME5 is located within − 1051 bp to + 35 bp. Two functional GC-boxes (− 300 bp and − 323 bp) were identified within the promoter region. Mutation of either GC-box led to significant reduction in NME5 promoter activity, whereas overexpression of Sp1 activated NME5 promoter activity in MIA PaCa-2 and 293T cells. In silico analysis predicted that transcription factor Sp1 binds to both GC-boxes, which were confirmed by EMSA and ChIP. In addition, we found that compared with MIA PaCa-2, Sp1 was highly expressed in PAXC002, a well characterized human pancreatic cancer cell line with innate gemcitabine resistance where NME5 was reported to be highly expressed, indicating that Sp1 induces NEM5 expression in PAXC002 cells. In conclusion, our study characterized for the first time the human NME5 promoter which is controlled by Sp1 transcription factor in pancreatic cancer.

Atrazine is an s-triazine herbicide that has been used widely over 50 years. This has resulted in the contamination of surface water, groundwater and soil. For the bioremediation of atrazine-contaminated environments, we investigated the biodegradation of atrazine and bioremediation of atrazine-contaminated soil by two groups of mixed bacteria (Pseudomonas sp. ADP and Arthrobacter aurescens TC1; Arthrobacter sp. AD30 and Pseudomonas sp. AD39) and a bacterial consortium. The biodegradation experiments indicated that after the minimal medium containing 300 mg/L atrazine as nitrogen source and 3000 mg/L sucrose as carbon source were inoculated with the above-mentioned two groups of mixed bacteria and bacterial consortium and incubated at 30°C with shaking for 48 h, atrazine were removed by 80% (ADP+TC1), 97% (AD30+AD39), and 96% (bacterial consortium), respectively. The bacterial consortium and the mixed bacteria containing Arthrobacter sp. AD30 and Pseudomonas sp. AD39 exhibited higher atrazine biodegradation activities. A bioremediation trial of atrazine-contaminated soil by the bacterial consortium and mixed bacteria containing AD30 and AD39 have indicated that after incubating for 15 d at 30°C atrazine contained in soil (100 mg/kg) were completely removed. These results indicated that the bacterial consortium and the mixed bacteria containing AD30 and AD39 are good candidates for use in bioremediation of atrazine-contaminated soil.

Rho kinase inhibition is beneficial for neurite outgrowth and nerve disorders, and the Rho kinase inhibitors have been regarded as promising agents to treat neural diseases. The main aim of the study was to elucidate how Rho kinase inhibitor Y-27632 regulates neurotransmitter norepinephrine synthesis and release in PC12 cells when neurite outgrowth was induced. PC12 cells were treated with Y-27632 for 6 days. The amount of norepinephrine synthesized in PC12 cells and the amount released evoked by acetylcholine or by KCl were determined by norepinephrine enzyme-linked immunosorbent assay kits. The results showed that the amount of norepinephrine both synthesized and released was down-regulated with a concentration-dependent relationship. Further results of Western blotting found that the protein expression of tyrosine hydroxylase and synapsin I (especially its active form, synapsin I phosphoSer603) was also down-regulated, which were directly related to synthesis and release of norepinephrine, respectively. All the results suggest that Y-27632 is able to down-regulate norepinephrine synthesis and release, the direct mechanism of which may be associated with down-regulation on expression of some proteins, including tyrosine hydroxylase and synapsin I.

The aim of the study was to discover possible differential cytotoxicity of triptolide towards estrogen-sensitive MCF-7 versus estrogen-insensitive MDA-MB-231 human breast cancer cells. Considering that MCF-7 cells express functional Estrogen receptor alpha (ERalpha) and wild-type p53, whereas MDA-MB-231 cells which are ERalpha-negative express mutant p53, the anti-proliferation effect of triptolide on MCF-7 and MDA-MB-231 cells were examined, the apoptotic effect and cell cycle arrest caused by triptolide were investigated, ERalpha and p53 expression were also observed in this paper. The results showed that the anti-proliferation effects were induced by triptolide in both cell lines. But the value of IC(50) in MCF-7 cells for its anti-proliferation effect was about one tenth of that in MDA-MB-231 cells, which indicated that the effect is more potent in MCF-7 cells. Condensed chromatin or fragmented nuclei could be found in MCF-7 cells treated with only 40nM triptolide but in MDA-MB-231 cells they couldn't be observed until the concentration reached to 400nM. Triptolide induced significant S cell cycle arrest along with the presence of sub-G0/G1 peak in MDA-MB-231 cells, whereas there was only slightly S cell cycle arrest on cell cycle distribution in MCF-7 cells. The role of p53 in two breast cancer cells was examined, the results showed that the mutant p53 in MDA-MB-231 cells was suppressed and the wild-type p53 in MCF-7 was increased. Moreover, triptolide could down regulate the expression of ERalpha in MCF-7 cells. The results showed that triptolide is much more sensitive to ERalpha-positive MCF-7 cells than to ERalpha-negative MDA-MB-231 cells, and the sensitivity is significantly associated with the ERalpha and p53 status.

Triptolide, a main active component extracted from the traditional Chinese herbal medicine, Tripterygium wilfordii Hook. f (TWHf), has been shown to possess potent immunosuppressive and anti-inflammatory properties. However, the toxicity of triptolide limits its clinical applications. Here we treated the human proximal tubular epithelial cell line HK-2 cells with triptolide in vitro and investigated its toxic effects. The cytotoxicity was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for viability inhibition and annexin V/propidium iodide (PI) staining for apoptosis/necrosis. The activation of caspase 3 was analyzed by Western Blotting. MTT assay showed triptolide inhibited the viability of HK-2 cells in a time- and dose-dependent manner. Flow cytometry assay showed triptolide caused apoptosis rather than necrosis in HK-2 cells by staining with annexin V/PI. Furthermore, the increase of cleaved p17 fragment, an active form of caspase 3, was detected. These results suggested that triptolide is able to cause cytotoxicity on HK-2 cells, and the mechanism of which is associated with caspase 3.

Triptolide, a purified diterpenoid triepoxide compound derived from a traditional Chinese medicine, Tripterygium wilfordii HOOK. f (TWHf), has been used in the treatment of autoimmune and inflammatory diseases. However, the toxicity of triptolide limits its application to a great extent. In the present study, we treated human normal liver L-02 cells (L-02 cells) with triptolide in vitro and investigated its toxic effects. The cytotoxicity was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for cellular viability and by flow cytometry and Hoechst 33258 staining for apoptosis. The mitochondrial membrane potential (delta psi m) was evaluated by flow cytometry with JC-1 as probe. After treatment with triptolide, a decrease in the viability of L-02 cells and increase in apoptosis were observed. Triptolide-induced apoptosis was accompanied by loss of mitochondrial membrane potential and release of cytochrome c (cyt-c) from the mitochondria to the cytosol and down-regulation of anti-apoptotic protein Bcl-2 levels with concurrent up-regulation in pro-apoptotic protein Bax levels and tumor suppressor protein p53 levels. Triptolide-increased activity of caspase 9 and caspase 3 was also observed. These results indicate that triptolide induced cytotoxicity in L-02 cells by apoptosis, which is mediated through mitochondrial pathway.

Emodin (1,3,8-trihydroxy-6-methyl-anthraquinone) and rhein (4,5-dihydroxyanthraquinone-2-carboxyl acid) are two main active compounds in total rhubarb anthraquinones (TRAs), which showed nephrotoxicity in Sprague Dawley (S.D.) rats in our previous study. However, it is unknown yet whether emodin and rhein have cytotoxic effects on kidney. To address this issue, HK-2 cells, a human proximal tubular epithelial cell line, were treated with different concentrations of emodin or rhein, and cell viability and morphological changes were investigated. The ratio of hypodiploid cells and the activity of caspase 3 protease were also detected. Results showed that addition of emodin but not rhein at concentrations above 40microM for 24h reduced cell viability and induced apoptosis in HK-2 cells. Additionally, emodin at apoptosis-inducing concentrations caused expression of cathepsin B (CB) protein and activation of CB protease. Addition of CB inhibitor, CA-074, significantly attenuated the ratio of hypodiploid and apoptotic cells, partially blocked caspase 3 activation and inhibited reduction of cell viability induced by emodin. These data indicate that emodin possesses cytotoxic effects on HK-2 cells partially through induction of CB protein and activation of CB protease.

We have investigated the antiproliferative effects of TBIDOM (N-(4-(2,2,2-trifluoroethyl) benzylidene) (7-isopropyl-1,4a-dimethyl-1,2,3,4,4a,9,10,10a-octahydrophenanthren-1-yl) meth-anamine) and have explored its possible mechanisms on human hepatocellular carcinoma SMMC-7721 cells. The proliferative status of cells treated with TBIDOM was measured by the colorimetric MTT assay. Cellular apoptosis was analysed using Hoechst 33342 staining and flow cytometry. Reduction of mitochondrial membrane potential (Δψm) was also detected by flow cytometry. Western blotting assay was used to evaluate the release of cytochrome c and expression of p53, Bcl-2 and Bax proteins. It was shown that TBIDOM displayed a significant inhibitory effect on growth of SMMC-7721 cells in a dose- and time-dependent manner. Hoechst 33342 staining and flow cytometry analysis showed an increase of apoptosis rate and decrease of mitochondrial membrane potential after SMMC-7721 cells were exposed to TBIDOM for 24 h. Pretreatment of SMMC-7721 cells with TBIDOM significantly induced a decrease of Bcl-2 protein expression and an increase of caspase-3 activity and Bax protein expression. The results indicated that TBIDOM could effectively inhibit proliferation by induction of apoptosis and could be a promising candidate in the development of a novel class of antitumour agent.

Cyclooxygenase 2 (COX-2) pathway inhibitors were regarded as promising nonsteroidal antiinflammatory drugs (NSAIDs). We discovered that the COX-2 pathway in A549 cells, a human lung cancer cell line, was activated by serum-free stimulation, and a drug screening model for NSAIDs was established based on this principle with simple performance and sufficient reliability. The COX-2 pathway was activated by treating with serum-free medium for 12 h. The activated cells were incubated with NS398 (selective COX-2 inhibitor), SC560 (selective COX-1 inhibitor), acetyl salicylic acid (ASA) (nonselective COX inhibitor) at 37 degrees C for 15 min. Then the cells were incubated with 10 microM of arachidonic acid (AA) for another 30 min prostaglandin E2 and 6-keto-prostaglandin F(1alpha) were assayed in an enzyme immunoassay (EIA). The results showed that the COX-2 pathway was dominant in A549 cells whether activated by serum-free medium or not, and the COX-1 pathway could be ignored. The model accepted the positive inhibition threshold as NS398 2 microM; if a compound (10 microM) inhibited COX-2 pathway more than NS398 (2 microM), it was regarded as a hit. The COX-2 pathway inhibition experiment showed that the Z;-factor of the screening model was 0.62, which suggests that the model is suitable for COX-2 pathway inhibitor screening.

A simple and sensitive method for the determination of triptolide, wilforlide A and triptonide in human plasma was developed and validated, using high-performance liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS). Plasma samples were purified using solid-phase extraction (SPE) columns. The HPLC separation of the analytes was performed on a MACHEREY-NAGEL C(18)column (2.0 mm x 125 mm, 3 microm), using 2.7 mM formic acid containing 10 mM ammonium acetate-acetonitrile (55:45, v/v) as mobile phase, with a flow-rate of 0.25 ml/min. The compounds were ionized in the electrospray ionization (ESI) ion source of the mass spectrometer and were detected in the selected ion recording (SIR) mode. The calibration curves were linear in the 0.80-300 ng/ml range for all the three analytes, and the limits of detection were 0.25, 0.40, and 0.35 ng/ml for triptolide, wilforlide A, and triptonide, respectively. The average absolute recoveries for all the three analytes were above 81%. The methodology recoveries were greater than 91% and the relative standard deviations (RSD) of intra-day and inter-day were less than 15%. The developed method was successfully applied to the determination of triptolide, wilforlide A and triptonide concentration in patients' plasma after taking the medicament containing Tripterygium wilfordii HOOK. F.