OBJECTIVETo investigate the contents of poison in fishes in the Zhoushan Fishery and to analysis its relationship with the degree of ocean pollution.

METHODNine kinds of major fishes in the Zhoushan Fishery were sampled and tested. Canonical correlation was conducted to evaluate the correlation between contents of poison in fishes and the degree of ocean pollution.

RESULTSThe average contents of nickel among 9 kinds of fishes exceeded normal value by 1.177 times. No significantly statistical differences were found between the levels of poison contents in nine kinds of major fishes during 1997 to 2003 in the Zhoushan Fishery (the P values are all less than 0.05), except that the levels of cadmium and hydrargyrum in some fishes (the P values are all more than 0.05). The coefficient of fishes accumulated from different poisons ranged from 101.80 to 71 210.97. The canonical correlation coefficients of the variables of the contents of plumbum, arsenic and benzene hexachloride, chlorophennothane between fishes and ocean were 0.784 and 0.808 respectively. Positive correlation between them was shown (chi(2) = 20.994, P < 0.01; chi(2) = 38.017, P < 0.01).

CONCLUSIONThe sanitary quality indexes of all poisons which had been tested fell in the normal ranges except for nickel. The degrees of poisons accumulated among distinct fishes varied, showing the relationship of medium positive correlation between the poison contents of fishes and the degree of the ocean pollution.

Animals ; China ; Fishes ; Food Contamination ; analysis ; Metals, Heavy ; analysis ; Nickel ; analysis ; Seawater ; analysis ; Water Pollutants ; analysis

OBJECTIVETo study the influence of inorganic elements in soil on the geolism of Atractylodes lancea.

METHODThe concentrations of 15 kinds of inorganic elements of regional A. lancea and their correspondingly soils were determined, and the data were analysed with the SPSS10.0 software.

RESULTThe mean concentration of Ni in geoherbs of A. lancea was 3 times higher than that in the non-geoherbs. The accumulation of Ca is high in geoberbs. There is no relationship between the concentrations of inorganic elements in A. lancea and those in their corresponding soil.

CONCLUSIONA. lancea adjusts the concentration of inorganic elements mainly by active absorption, and there are good relationship between the accumulation of Fe and Cr, Fe and Hg, Hg and Cr, As and Pb, Co and Sr.

Atractylodes ; chemistry ; Calcium ; analysis ; Chromium ; analysis ; Fluorocarbons ; analysis ; Geologic Sediments ; analysis ; Iron ; analysis ; Nickel ; analysis ; Plants, Medicinal ; chemistry ; Rhizome ; chemistry ; Soil ; analysis

Genotypic and environmental variation in Cd, Cr, As, Ni and Pb concentrations of grains, and the relationships between these heavy metals and Fe, Zn were investigated using 9 rice genotypes grown in 6 locations for two successive years. Significant genotypic variation was detected in the five heavy metal concentrations in grains, indicating the possibility to reduce the concentration of these heavy metals in grains through breeding approach. The environmental effect varied with metal, with Pb and Ni having greater variation than the other three metals. There was significant genotype-environment (location) interaction of the concentrations of all five heavy metals in grains, suggesting the importance of cultivar choice in producing rice with low heavy metal concentrations in grains for a given location. Correlation analysis showed that Cd and As, Cr and Ni, and As and Pb concentrations in rice grains were closely associated, and that Ni concentration in grains was negatively correlated with Zn concentration.
Arsenic ; analysis ; Cadmium ; analysis ; Chromium ; analysis ; Edible Grain ; chemistry ; genetics ; Environment ; Genetic Variation ; genetics ; Genotype ; Lead ; analysis ; Metals, Heavy ; analysis ; Nickel ; analysis ; Oryza ; chemistry ; genetics ; Soil Pollutants ; analysis

OBJECTIVETo investigate the mechanical properties of Ni-Ti wires with direct electric resistance heat treatment (DERHT) method in three-point bending tests.

METHODSTwo superelastic Ni-Ti wires (wire A: Smart SE, wire B: SENTALLOY SE, 0.406 mm × 0.559 mm) and 2 heat-actived Ni-Ti wires (wire C: Smart SM, wire D: L&H TITAN, 0.406 mm × 0.559 mm) were selected. They were heat-treated using the DERHT method by a controlled electric current (6.36 A) applied for different period of time [0 (control), 1.0, 1.5, 2.0, 2.5 seconds). Then, a three-point bending test was performed under controlled temperature (37°C) to examine the relationships between the deflection and the load in the bending of wires.

RESULTSAfter DERHT treatment, the plateau in the force-deflection curve of superelastic Ni-Ti wires and heat-activated Ni-Ti wires were increased. When the wires were heated for 2.0 seconds and deflected to 1.5 mm, the loading force of A, B, C and D Ni-Ti wires increased from (3.85 ± 0.11), (3.62 ± 0.07), (3.28 ± 0.09), (2.91 ± 0.23) N to (4.33 ± 0.07), (4.07 ± 0.05), (4.52 ± 0.08), (3.27 ± 0.15) N respectively.

CONCLUSIONSDERHT method is very convenient for clinical use. It is possible to change the arch form and superelastic force of NiTi wires. The longer the heating time is, the more the superelastic characteristics of the wires are altered.

Dental Stress Analysis ; Elasticity ; Hot Temperature ; Materials Testing ; Nickel ; chemistry ; Orthodontic Wires ; Stress, Mechanical ; Titanium ; chemistry

OBJECTIVETo evaluate the biological safety of compound galvano-ceramic bridge by measuring the consistency of released nickel ion of the galvano-form slices cohered with Ni-Cr alloy slice specimens which were immersed in artificial saliva.

METHODSSpecimens were divided into five groups with four tests and one control. Test specimens were made into the structure like rectangle sandwich that one side of Ni-Cr alloy was cohered to the center surface of galvano golden base of 0.2 mm and another side was fused porcelain with the thickness of 0.3 mm (group A), 0.5 mm (group B), 1.0 mm (group C), and 0.3 mm (group D). And the Ni-Cr alloys were totally embedded in galvano golden base and firing porcelain. Naked Ni-Cr alloy was taken as control. Group D was immersed into acid artificial saliva (AS) with high fluoride, while others were in acid AS at 37 degrees C for 120 h. Then the consistency of released nickel ion in the solution was measured with inductively coupled plasma-atomic emission spectrometry (ICP-AES).

RESULTSNickel ions detected in the artificial saliva for the groups A, B, C, and D in acid AS with or without high fluoride were all under 0.005 mg/L Significant differences were found between each test group and the control [(0.65 +/- 0.45) mg/L].

CONCLUSIONSGalvano-ceramic bridge, Ni-Cr alloy bridge with fused porcelain and golden base, shows biological safety responsible for the consistency of released nickel ion.

Biocompatible Materials ; chemistry ; Dental Materials ; Materials Testing ; Metal Ceramic Alloys ; chemistry ; Nickel ; analysis

Although many studies on the cytotoxicity of the dental cast metal alloys and their components have been carried out, the results are rather conflicting because of the different type of cells used and the various experimental procedures taken. Recently, a number of scientists have claimed that it would be preferable to focus on the use of cells from relevant specific location of the human bodies. Consequently, the primary cultured oral keratinocyte derived from oral mucous along with nickel chloride and several of widely used dental cast base metal alloys(two-Ni-Cr alloys and one Co-Cr alloy)in domestic were selected for this study, from which 1) The amounts of released metal ions were determined using atomic absorption spectrometry, 2) The cytotoxicity of nickel chloride and dental cast base metal alloys was evaluated via MTT assay, and finally, 3) The amounts of released metal ions and the cytotoxicity of nickel chloride were correlated with the cytotoxicity of dental cast base metal alloys And, the results were summarized as follows ; 1. Nickel ion from Ni-Cr alloys and Cobalt ion from Co-Cr alloys resulted in maximum releasing rate during first 24 hours, followed by a decrease in releasing rate with time. Chromium ion were found to be minimal in all alloys. 2. In cytotoxic test, with 40muM, 80muM of nickel chloride, there were observed an increase in the relative cell number compared to control samples after 24 hours. With 160muM, there was found to be no difference in the relative cell number with control, except that 48 hour showed a increase in relative cell number. With 320muM, the relative cell number remained constant and decreased after 48 hours, and with 640muM, a continuing decrease in relative cell number was observed throughout test period. 3. The sensitivity of primary cultured oral epithelium to nickel was lower compared to the cells used in other studies. 4. CB-80 Soft and Regalloy showed no cytotoxicity to primary cultured oral epithelium and New crown resulted in a slight cytotoxicity. In conclusion, it was shown that the primary cultured oral keratinocytes could be applied successfully as testing cells in cytotoxicity test. Futhermore, the dental cast base metal alloys used in this study were found to be biocompatible.
Absorption ; Alloys* ; Cell Count ; Chromium ; Cobalt ; Crowns ; Epithelium ; Human Body ; Humans* ; Ions ; Keratinocytes* ; Nickel ; Spectrum Analysis

OBJECTIVEThis study was to investigate the mechanical properties of thermodynamic nickel-titanium (NiTi) archwires of different brands under controlled temperature and in artificial saliva to provide some reference for its clinical application.

METHODSUsing a modified partial dental arch bending system, four types of thermodynamic NiTi archwires were tested under controlled temperature (25, 33, 37, 60 degrees C) and in artificial saliva. An Instron Universal Testing Machine was used to apply 3 mm deflections of archwires in the lateral incisor area. The load-deflection curves were determined from the passive position to deflections of 3 mm. The following variables from unloading curves were calculated: Stiffness between 2.5 mm UDP (unloading deflection point) to 0.5 mm UDP after unloading. Any statistically significant differences in these variables for the different brands, temperature and moments levels were analyzed using one-way analysis of variance.

RESULTSUnloading values of four types thermodynamic nickel-titanium archwires increased with controlled temperature rising. The unloading stiffness of the same brand archwires were approximate at 25, 33, 37 degrees C, while their unloading stiffness increased obviously at 60 degrees C.

CONCLUSIONDifferent brands thermodynamic NiTi archwires demonstrated different mechanical behaviours, but all of them exhibited super elasticity and practical shape memory effect. The four thermodynamic NiTi archwires displayed temperature sensitivity at the four test temperatures.

Dental Alloys ; Dental Stress Analysis ; Elasticity ; Humans ; In Vitro Techniques ; Materials Testing ; Nickel ; Orthodontic Wires ; Temperature ; Titanium

OBJECTIVE: To construct a model for a controlled memory (CM) nickel-titanium (NiTi) file and another M-wire NiTi file with the same geometry by using finite element analysis. To evaluate the flexibility of a CM NiTi file by using three dimensional finite element method and to compare its mechanical responses with that M-wire NiTi. METHODS: Based on the reverse engineering, the 21 mm long, 25#/08 taper Hyflex NT NiTi file and Hyflex CM NiTi file were fixed by the cantilever bending model at a distance of 9.5 mm from the tip of the file. The mechanical tester's indenter was loaded/unloaded at a distance of 3 mm from the tip of the file. The maximum displacement was 3 mm, the load displacement curve was obtained. Subsequently, by using a micro-CT to scan (layer spacing of 8 μm) NiTi files, and ABAQUS (6.10) was introduced to construct a geometric model. Hyflex NT was considered as a shapememory alloy constitutive model, Hyflex CM was considered as a power-hardening plastic constitutive model, respectively. Comparing the load-displacement curve of cantilever bending in the three-dimensional finite element model with the load-displacement curve in the experiment. RESULTS: Two tetrahedral element models were constructed, the total number of nodes was 99 353 and the total number of cells was 63 744. When the loading displacement was 1 mm, the stress distribution of the cross section at 6.1 mm from the tip of the file was observed. The upper and lower surfaces were subjected to the maximum bending stress and entered the phase transformation yield stage. The finite element simulation could clearly show the deformation of the file. Various information such as deformation characteristics and stress distribution in the process were well fitted to the actual experimental curve. CONCLUSION The constitutive behavior of the material has a significant effect on the mechanical behavior of NiTi file. The finite element model established for the NiTi file of the CM wire can accurately capture the characteristics of various deformation processes of the NiTi root canal file, and it has a good fit with the actual experimental curve. The finite element model can be used for study on bending properties of CM wire.
Dental Alloys ; Equipment Design ; Finite Element Analysis ; Materials Testing ; Nickel ; Root Canal Preparation ; Stress, Mechanical ; Titanium

In order to evaluate the safety performance of self-expandable NiTi alloy stents systematically, the dynamic safety factor drawn up by International Organization for Standardization, was used to quantitatively reflect the safety performance of stents. Based on the constitutive model of super-elastic memory alloy material in Abaqus and uniaxial tensile test data of NiTi alloy tube, finite element method and experiments on accelerated fatigue life were carried out to simulate the self-expansion process and the shape change process under the action of high and low blood pressure for three -type stents of 8×30 mm, 10×30 mm, 12×30 mm. By analyzing the changes of stress and strain of self-expanding NiTi alloy stent, the maximum stress and strain, stress concentration position, fatigue strength and possible failure modes were studied, thus the dynamic safety factor of stent was calculated. The results showed that the maximum stress and plastic strain of the stent increased with the increase of grip pressure, but the maximum stress and strain distribution area of the stent had no significant change, which were all concentrated in the inner arc between the support and the connector. The dynamic safety factors of the three stents were 1.31, 1.23 and 1.14, respectively, which indicates that the three stents have better safety and reliability, and can meet the fatigue life requirements of more than 10 years, and safety performance of the three stents decreases with the increase of stent's original diameter.
Alloys ; Finite Element Analysis ; Nickel ; Reproducibility of Results ; Self Expandable Metallic Stents ; Stress, Mechanical ; Titanium

OBJECTIVE: To seek a exact method of estimating postmortem interval (PMI). METHODS: This study detected the concentration of zincum(Zn) and nickel(Ni) in vitreous humor of rabbit at hour 96 after death and explored the relationship between their concentration and PMI using a method ICP-MS. RESULTS: The concentration of Zn and Ni in vitreous humor of rabbit at hour 24 after death were related to PMI significantly; The formulae of the relationship between PMI and Zn concentrations is y = 0.1404x2 - 1.3351x + 3.8298 (within 24 h; R2 = 0.9202). The formula of the relationship between PMI and Ni concentrations is y = 0.0043x2 - 0.0596x + 0.2665(within 24 h; R2 = 0.9103). CONCLUSION The concentration of Zn and Ni in vitreous humor of rabbit may be a reference indicator to estimate early PMI.
Animals ; Female ; Forensic Medicine ; Male ; Nickel/analysis* ; Postmortem Changes ; Rabbits ; Time Factors ; Vitreous Body/chemistry* ; Zinc/analysis*