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1.
1　Introduction　Ahugeamountofliteratureexistsonthestudyofi dentifyingtracemetalionsbymeansofspectropho tometry[1 3] ,fluorimetry[4 6 ] aswellas polarogra phy[7 9] ,whichhaveactiononlocatingtheendpointoftheindicatingreaction .Howeverbothspectropho tometryandfluorimetryareeasytobeinterferedbycolororprecipitation ,whilepolarographyhasanissueofmercurypollution .Thecatalyzingkineticanalysishasthecharacteristicsofhighsensitivityandspeedi ness.Oscillographicpotentiometryisasimpleintu itionisticanal…  相似文献   

2.
1, 10-Phenanthroline (phen) was tested as a complexing agent for on-line preconcentration of iron on RP-C18 material in a microcolumn with flow injection coupled with flame atomic absorption spectrometer (FI-FAAS). The on-line formed Fe(II)-phen complexes were adsorbed on the C18 sorbent material. Various parameters affecting the on-line Fe(II)-phen complex formation and its subsequent adsorption in the microcolumn as well as its elution into the nebulizer of AAS were optimized. A 2.5×10−3 mol/L phen in 2% through the microcolumn for 30 s. The adsorbed Fe(II)-phen complexes in the microcolumn were eluted with ethanol in 10 s into the nebulizer of AAS. Ascorbic acid (5×10−4 mol/L) was added to the sample solution for the reduction of Fe(III) to Fe(II). A good precision (RSD=1.1%,n=10), high enrichment factor (19) and sample throughput (90 h−1) with detection limit (3σ) of 3 μg/L were obtained. The method was applied on standard reference materials (i. e. mussel and tomato leaves,) for iron determination and yielded results agreeing well with certified values. Project supported by the Zhejiang Provincial Natural Science Foundation of China and Zhejiang Environmental Protection Foundation From Pakistan Institute of Nuclear Science & Technology, Islamabad, Pakistan and now ZJ University, Ph. D. student.  相似文献   

3.
1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　Ｔｈｅｃｈｅｍｉｃａｌｅｆｆｅｃｔｓｏｆｕｌｔｒａｓｏｕｎｄａｒｅｄｕｅｔｏｈｉｇｈｐｒｅｓｓｕｒｅｐｒｏｄｕｃｅｄｄｕｒｉｎｇｖｉｏｌｅｎｔｃｏｌｌａｐｓｅｏｆｃａｖｉｔａｔｉｏｎｂｕｂｂｌｅｓ.Ｔｈｅｒｅａｃｔｉｏｎｓｄｏｎｏｔｔａｋｅ ｐｌａｃｅｈｏｍｏｇｅ ｎｅｏｕｓｌｙｉｎｔｈｅｓｏｌｕｔｉｏｎｂｕｔｉｎ”ｈｏｔｓｐｏｔｓ”ｗｈｅｒｅｃａｖｉ ｔａｔｉｏｎｂｕｂｂｌｅｓｐｕｌｓａｔｅｏｒｃｏｌｌａｐｓｅ .Ｄｕｒｉｎｇｔｈｅａｄｉａｂａｔ ｉｃｃｏｍｐｒｅｓｓｉｏ…  相似文献   

4.
Objective: To investigate the influence of lead exposure on the immune function of lymphocytes and erythrocytes in preschool children. Materials and methods: A group of 217 children three to six years of age from a rural area were given a thorough physical examination and the concentration of lead in blood samples taken from each subject was determined. The indices of lymphocyte immunity (CD 3CD 4, CD 3CD 8, CD 4CD 8, CD-3CD 19) and erythrocyte immunity (RBC-C3b, RBC-IC, RFER, RFIR, CD35 and its average fluorescence intensity) of 40 children with blood lead levels above 0.483 μmol/L were measured and compared with a control group. Results: The blood lead levels of the 217 children ranged from 0.11 μmol/L to 2.11 μmol/L. The CD 3CD 4and CD 4CD 8 cells were lower (P＜0.01) and the CD 3CD 8 cells were higher in the lead-poisoned subjects than those in the control group (P＜0.05). CD 3 and CD-3CD 19 did not show significant differences. Although the RBC-C3b rosette forming rate was lower and the RBC-IC rosette forming rate was higher in the lead-poisoned group, this difference could not be shown to be statistically significant (P＞0.05). RFIR was found to be lower in the lead-poisoned group (P＜0.01). Compared with the control group, the positive rate of CD35 was not found to be significantly different in a group of 25 lead-poisoned children (P＞0.05), while the average fluorescence intensity was lower in the lead-poisoned group (P＜0.05). Conclusion: Lead exposure can result in impaired immune function of T lymphocytes and erythrocytes in preschool children.  相似文献   

5.
We report an important observation that the surface conductivity of antibody layer immobilized on polylysine-coated glass substrate decreases upon the formation of complex with their specific antigens. This change in conductivity has been observed for both monoclonal and polyclonal antibodies. The conductance of monoclonal mouse IgG immobilized on polylysine-coated glass substrate changed from 1.02×10−8 Ω−1 to 1.41×10−11 Ω−1 at 10 V when complex is formed due to the specific biomolecular interactions with rabbit anti-mouse IgG F(ab′)2. Similar behavior was observed when the same set up was tested in two clinical assays: (1) anti-Leishmania antigen polyclonal antibodies taken from Kala Azar positive patient serum interacting with Leishmania promastigote antigen, and (2) anti-p21 polyclonal antibodies interacting with p21 antigen. The proposed concept can represent a new immunodiagnostic technique and may have wide ranging applications in biosensors and nanobiotechnology too.  相似文献   

6.
A simple and controllable layer-by-layer (LBL) assembly method was proposed for the construction of reagentless biosensors based on electrostatic interaction between functional multiwall carbon nanotubes (MWNTs) and enzyme-mediator biocomposites. The carboxylated MWNTs were wrapped with polycations poly(allylamine hydrochloride) (PAH) and the resulting PAH-MWNTs were well dispersed and positively charged. As a water-soluble dye methylene blue (MB) could mix well with horseradish peroxidase (HRP) to form a biocompatible and negativelycharged HRP-MB biocomposite. A (PAH-MWNTs/HRP-MB) n bionanomultilayer was then prepared by electrostatic LBL assembly of PAH-MWNTs and HRP-MB on a polyelectrolyte precursor film-modified Au electrode. Due to the excellent biocompatibility of HRP-MB biocomposite and the uniform LBL assembly, the immobilized HRP could retain its natural bioactivity and MB could efficiently shuttle electrons between HRP and the electrode. The incorporation of MWNTs in the bionanomultilayer enhanced the surface coverage concentration of the electroactive enzyme and increased the catalytic current response of the electrode. The proposed biosensor displayed a fast response (2 s) to hydrogen peroxide with a low detection limit of 2.0×10−7 mol/L (S/N=3). This work provided a versatile platform in the further development of reagentless biosensors.  相似文献   

7.
The effects of salinity(50 mmol/L NaCl) and Cd(1 μmol/L CdCl2) as sole and combined on growth and photosyn-thetic parameters were studied using two soybean genotypes,Huachun 18 and NGB.The concentrations of Cd2 ,Zn2 ,Ca2 ,Mg2 ,K and Na were also determined in seeds and pods.Huachun 18 suffered a more serious decrease than NGB in net photosynthetic rate(Pn) in the treatments of salinity stress alone and combined stress(NaCl Cd),showing that it is relatively sensitive to salinity.The decrease in Pn caused by salt stress in Huachun 18 was mainly due to the reduced total chlorophyll content and photosynthetic efficiency(the ratio of variable fluorescence to maximal fluorescence,Fv/Fm),whereas the decease in NGB was mainly related to reduced stomatal conductance(Gs).The combined stress of both Na and Cd did not induce further decrease in photosynthesis and fluorescence in the two genotypes relative to salt or Cd stress alone.Greater change in the pod concentrations of Zn2 ,Ca2 ,Mg2 ,K and Na was detected under salt stress for Huachun 18 than for NGB.The results suggested that the interactive effect of NaCl-Cd on growth and nutrient uptake differs between the two soybean genotypes.  相似文献   

8.
Well-cubic perovskite lanthanum aluminate (LaAlO3) film on (110) silicon substrate was fabricated by sol-gel method with corresponding inorganic salts. Lanthanum acetate and aluminum acetate glacial acetic acid solutions were prepared via ligand exchange starting from lanthanum nitrate hexahydrate and aluminum nitrate hexahydrate after being refluxed. (CH3CO)2O removed nitrates and the crystallized H2O completely, acetylacetone (AcAc) was partially bidentated with metallic ion of the metallic acetates and formed La(OAc)3−x (AcAc) x which were hydrolyzed into La(AcAc)3−x(OH) x by adding 10 ml 0.4% methyl cellulose (MCL) solution. The La(AcAc)3−x (OH) x , polymerizing and combining with MCL, formed the LaAlO3 sol precursor with heteropolymeric structure and formed film easily. The epitaxial LaAlO3 film on Si(110) substrate was crystallized after being annealed in thermal annealing furnace for 650–750 °C/30 min. The morphologies and microstructures were characterized. The refractive index of the LAO film was 1.942 to 2.007; the dielectric constant and the dissipation factors were estimated to be 23–26 and 2.1×10−4−2.4×10−4 respectively. Project (No. 2002CB613305) supported by the National Basic Research Program (973) of China  相似文献   

9.
INTRODUCTION Nitrogen oxide (NOx) is one of the main air pol- lutants found in the flue gases from chemical and power plants belching acid rain and photochemical smog. Over 90 percent of all man-made nitrogen ox- ides that enter our atmosphere are produced by the combustion of various fuels. Compared with the ad- vanced stage of SO2 gas removal technologies devel- opment, the removal of NOx gases is still in the initial stages of development as roughly 90 to 95 percent of NOx emitted i…  相似文献   

10.
Osteochondral allografting has been proved to be a useful method to treat diseased or damaged areas of joint surfaces. Operational long-term stocks of grafts which supply a buffer between procurement and utilization would contribute to the commercialization or industrialization of this technology. Vitrification has been thought to be a promising method for successful preservation of articular cartilage (AC), but high concentration cryoprotectants (CPAs) are used which may cause high cellular toxicity. An effective way to reduce CPA toxicity is to increase CPA concentration gradually while the temperature is lowered. Understanding the mechanism of CPA permeation at subzero temperatures is important for designing the cryopreservation protocol. In this research, the permeation of dimethyl sulfoxide (Me2SO) in ovine AC at subzero temperatures was studied experimentally. Pretreated AC discs were exposed in Me2SO solutions for different time (0, 5, 15, 30, 50, 80, and 120 min) at three temperature levels (−10, −20, and −30 °C). The Me2SO concentration within the tissue was determined by ultraviolet (UV) spectrophotometry. The diffusion coefficients were estimated to be 0.85×10−6, 0.48×10−6, and 0.27×10−6 cm2/s at −10, −20, and −30 °C, respectively, and the corresponding activation energy was 29.23 kJ/mol. Numerical simulation was performed to compare two Me2SO addition protocols, and the results demonstrated that the total loading duration could be effectively reduced with the knowledge of permeation kinetics.  相似文献   

11.
Objective: To observe the effect of Yangxueqingnao particles on rat vascular smooth muscle cell (VSMC) proliferation induced by lysophosphatidic acid (LPA). Methods: The amount of3H-TdR (3H-thymidine) admixed in cultured rat VSMC was measured and mitogen-activated protein kinase (MAPK) activity and lipid peroxidation end product malondialdehyde (MDA) content of the VSMC were assayed. Results: 1×10−9, 1×10−8, 1×10−7 mol/L LPA in a concentration dependent manner, induced the amount of3H-TdR admixed, MAP kinase activity, and MDA content of the cultured rat VSMC to increase. However, 5%, 10%, and 15% Yangxueqingnao serum preincubation resulted in a decrease of 23.0%, 42.0%, and 52.0% (P<0.01) respectively in the amount of3H-TdR admixed, a decline in VSMC MAP kinase activity of 13.9% (P<0.05), 29.6% (P<0.01), and 48.9% (P<0.01) respectively, and also, a decrease in MDA content of VSMC of 19.4%, 24.7%, and 43.2% (P<0.01) respectively, in the 1×10−7 mol/L LPA-treated VSMC. Conclusions: LPA activates the proliferation and lipid peroxidation of VSMC in a concentration dependent manner. The LPA-induced VSMC proliferation is related to the activity of MAP kinases, enzymes involved in an intracellular signalling pathway. The results of the present study showed that Yangxueqingnao particles can effectively inhibit LPA-induced VSMC proliferation, MAP kinase activation, and reduce lipid peroxidative lesion. Project (No. 491010-W50339) supported by Chinese Traditional Medicine Administration Bureau of Zhejiang Province, China  相似文献   

12.
It is of great importance to investigate an effective and reliable medication against chronic renal failure (CRF)-related erectile dysfunction (ED), which aims to improve patients’ life qualities. The concentrations of cyclic guanosine monophosphate (cGMP) in the corpus cavernosal smooth muscle of both CRF and control rabbits were measured. The effects of various concentrations of tadalafil, papaverine, and sodium nitroprusside on the relaxation responses of corpus cavernosal smooth muscle pre-contracted with phenylephrine in CRF rabbits were observed. There was significant difference in the concentration of cGMP between CRF and control rabbits (P<0.01). Tadalafil had the greatest impacts on CRF rabbits when given the same concentration of papaverine or sodium nitroprusside and particularly significant differences were identified under the concentration levels of 10−5 and 10−4 mol/L (P<0.01). The results suggest that the cGMP concentrations of the corpus cavernosum had been greatly reduced in CRF rabbits compared with control rabbits and that tadalafil may be an ideal medication for use in the treatment of CRF-related ED.  相似文献   

13.
β-glucanase was purified from a solid-state culture ofTrichoderma reesei on wheat bran in three steps which comprised ammonium sulfate precipitation, Sephadex G-100 chromatography, and DEAE-Sephadex A-50 chromatography. The molecular mass was determined to be 35.21 kilodaltons by sodium dodecyl sulfate-12.5% polyacrylamide gel electrophoresis. The β-glucanase at low pHs was more stable than that at high pHs, and optimum pH was 5.0. The optimum temperature was 60°C, and β-glucanase was relatively stable at below 40°C for 60 min. TheK m of the enzyme on β-glucan was 10.86 mg/ml, and theV max on β-glucan was 14286 μmol of glucose equivalents per mg of the pure enzyme per min. The β-glucanase activity was significantly inhibited by Fe3+ ions, and was reduced in the presence of Cu2+ ions, Mn2+ ions and Mg2+ ions at 5 mmol/L and 10 mmol/L, respectively. The β-glucanase activity was stimulated by Co2+ ions, Ca2+ ions, Zn2+ ions, and Fe2+ ions at 1 mmol/L and 5 mmol/L, respectively. Project supported by Foundation for University Key Teacher of the State Ministry of Education, the National Natural Science Foundation of China (No. 30000118) and Zhejiang Provincial Natural Science Foundation of China (No. 399409).  相似文献   

14.
1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　Ｔｈｅｆｕｎｄａｍｅｎｔａｌｐｈｙｓｉｃａｌｍｅｔａｌｌｕｒｇｙｏｆｔｈｅｒｍｏｍｅｃｈａｎｉｃａｌｐｒｏｃｅｓｓｉｎｇ(ＴＭＰ)ｈａｓｂｅｃｏｍｅｍｕｃｈｂｅｔｔｅｒｕｎｄｅｒｓｔｏｏｄｏｖｅｒｔｈｅｌａｓｔｔｗｏｄｅｃａｄｅｓ[1～8].ＩｔｉｓｗｅｌｌｃｏｍｍｏｎｌｙｒｅｃｏｇｎｉｚｅｄｔｈａｔｔｈｅｍｉｎｕｔｅａｄｄｉｔｉｏｎｏｆｓｔｒｏｎｇｃａｒｂｏｎｉｔｒｉｄｅｏｒｎｉｔｒｉｄｅｆｏｒｍｉｎｇｅｌｅｍｅｎｔｓｓｕｃｈａｓＮｂ,ＴｉａｎｄＶｔａｋｅｓｖｅｒｙｉｍｐ…  相似文献   

15.
A rapid sample treatment procedure for the gas chromatography-tandem mass spectrometry (GC-MS) determination of 19-nortestosterone (19-NT) in animal tissues has been developed. In our optimized procedures, enzymatic hydrolysis with β-glucuronidase from Escherichia coli was performed in an acetate buffer (pH 5.2, 0.2 mol/L). Next, the homogenate was mixed with methanol and heated at 60 °C for 15 min, then placed in an ice-bath at −18 °C for 2 h. After liquid-liquid extraction with n-hexane, the analytes were subjected to a normal-phase solid phase extraction (SPE) C18 cartridge for clean-up. The dried organic extracts were derivatized with heptafluorobutyric anhydride (HFBA), and then the products were injected into GC-MS. Using electron impact mass spectrometry (EI-MS) with positive chemical ionization (PCI), four diagnostic ions (m/z 666, 453, 318, and 306) were determined. A standard calibration curve over the concentration range of 1–20 ng/g was reached, with Y=467 084X-68 354 (R 2=0.999 7) for 19-NT, and the detection limit was 0.3 ng. When applied to spiked samples collected from bovine and ovine, the recoveries ranged from 63% to 101% with relative standard deviation (RSD) between 2.7% and 8.9%. The procedure is a highly efficient, sensitive, and more economical method which offers considerable potential to resolve cases of suspected nandrolone doping in husbandry animals.  相似文献   

16.
Infrared （IR） absorption spectra and X-ray powder diffraction （XRD） patterrns of sexpenfine cat＇s eye from Sichuan Province have been investigated, and infrared absorption bands of the serpentine have been assigned in this paper. The results indicate that the bands near 3 600 - 3 700 cm^-1 belong to the stretching absorption band VOH, the bands in 948 - 1 100 cm^-1 axe assigned to the stretching vibraling band Usvo, and the bands at 600 570 and 440 cm^-1 respectively belong to the bending vibration band VOH, δMg-O and δSi-O. The serpentine cat＇ s eye includes two types： chrysotile and antigorite. Chrysotile has a sharp and intensive band at 3 688 cm^-1 and a weak band at 3 643 cm^-1 , while antigorite has only one intensive band in the region. At vibration band VSi-O, chrysotile and antigorite have a similar feature at 1 071 cm^-1, but the band at 980 cm^-1 in anfigorite has been split into two bands in chrysotile - a strong one at 1 027 cm^-1 and a weak one at 949 cm^-1. In addition, antigorite has a characteristic bending vibrating band δMg-O at 570 cm^-1. Based on the analysis of the feature of crystal structure, their IR differences axe well explained.  相似文献   

17.
SO4^2- / TiO2-La2O3, a novel solid superacid, was prepared and its catalytic activities at different synthetic conditions are discussed with esterification of n-butanoic acid and n-butyl alcohol as probing reaction. The optimum conditions have also been found, mole ratio of n（La^3＋）：n（Ti^4＋） is 1：34, the soaked consistency of H2SO4 is 0.8 tool/L, the soaked time of HESO4 is 24 h, the calcining temperature is 480 ℃, the calcining time is 3 h. Then it was applied in the catalytic synthesis often important ketals and acetals as catalyst and revealed high catalytic activity. Under these conditions on which the molar ratio of aldehyde/ketone to glycol is l： 1.5, the mass ratio of the catalyst used in the reactants is 0.5%, and the reaction time is 1.0 h, the yields of ketals and acetals can reach 41.4%-95.8%.  相似文献   

18.
Selenocosmia huwena and Selenocosmia hainana are two tarantula species found in southern China. Their venoms contain abundant peptide toxins. Two new neurotoxic peptides, huwentoxin-III (HWTX-III) and hainantoxin-VI (HNTX-VI), were obtained from the venom using ion-exchange chromatography and reverse-phase high performance liquid chromatography (RP-HPLC). The mechanism of action of HWTX-III and HNTX-VI on insect neuronal voltage-gated sodium channels (VGSCs) was studied via whole-cell patch clamp techniques. In a fashion similar to δ-atracotoxins, HNTX-VI can induce a slowdown of current inactivation of the VGSC and reduction in the peak of Na+ current in cockroach dorsal unpaired median (DUM) neurons. Meanwhile, 10 μmol/L HNTX-IV caused a positive shift of steady-state inactivation of sodium channel. HWTX-III inhibited VGSCs on DUM neurons (concentration of toxin at half-maximal inhibition (IC50)≈1.106 μmol/L) in a way much similar to tetrodotoxin (TTX). HWTX-III had no effect on the kinetics of activation and inactivation. The shift in the steady-state inactivation curve was distinct from other depressant spider toxins. The diverse effect and the mechanism of action of the two insect toxins illustrate the diverse biological activities of spider toxins and provide a fresh theoretical foundation to design and develop novel insecticides.  相似文献   

19.
To test the hypothesis that the etiology of reading difficulties may differ for males and females in more severely impaired samples, reading performance data from monozygotic (MZ), same-sex dizygotic (DZss), and opposite-sex dizygotic (DZos) twin pairs were analyzed using a model-fitting implementation of the DeFries-Fulker (DF) model (Purcell & Sham, 2003, Behavior genetics, 33, 271–278). Five non-independent samples were selected using cut-offs of −1 (N = 737 pairs), −1.5 (N = 654), −2 (N = 468), −2.5 (N = 335), and −3 (N = 198) standard deviations (s) below the mean composite reading score of control twins. Male/female gender ratios for children with reading difficulties were significantly higher than 1.0 for all five samples and increased as a function of severity (viz., 1.15, 1.17, 1.40, 1.61, and 1.88, respectively). When the DF model was fit to the data, estimates of heritability (h g2) and shared environmental influences (c g2) were not significantly different for males and females in any of the groups. Consequently, the most parsimonious model that provided a good fit to the data at all five levels of severity equated the heritabilities and shared environmental influences for males and females, and fixed the DZos coefficient of genetic relatedness at 0.5. Thus, these results provide no evidence for a differential etiology of reading difficulties as a function of gender in more severely impaired samples, and suggest that the same genetic and environmental influences contribute to reading difficulties in males and females, irrespective of severity.  相似文献   

20.
１ＩｎｔｒｏｄｕｃｔｉｏｎＤｉｆｅｒｅｎｔｉａｌｅｑｕａｔｉｏｎｓｗｉｔｈｔｕｒｎｉｎｇｐｏｉｎｔｓｅｘｉｓｔｗｉｄｅｌｙｉｎｍａｎｙｐｒｏｂｌｅｍｓｏｆｍａｔｈｅｍａｔｉｃｓｐｈｙｓｉｃｓ,ｓｏｔｈｅｓｅｐｒｏｂｌｅｍｓａｒｅｖｅｒｙｉｍｐｏｒｔａ...  相似文献   

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