SPECTROPHOTOMETRIC DETERMINATION OF LANTHANUM AND SUM OF OTHER LIGHT RARE-EARTHS BY FLEXIBLE TOLERANCE SIMPLEX-METHOD

The absorptivities of color elements in a mixture can be obtained by using Gauas' elimination with selection of principal element in matrix to the standards. These values can be applied to flexible tolerance simplex method to give the composition of samples. In the exprimental design and data treatment, an effort was made to minimize the errors of results according the principal of optimization. When the difference of absorptivities of color material is significant to the exprimental error, the pr...

STUDIED ON THE SIMULTANEOUS SPECTROPHOTOMETRIC DETERMINATION OF INORGANIC MULTICOMPONENT SYSTEMS .3. DETERMINATION OF MICROAMOUNTS OF TUNGSTEN, MOLYBDENUM AND TITANIUM

The absorption spectra of W, Mo and Ti-phenylfluorone cetyltrimethylammonium bromide complexes and the optimum conditions for the simultaneous spectrophotometric determination of microamounts of W, Mo and Ti were studied. In order to examine the effect of the errors of calibration matrix on the analytical resulte, the approach of selecting the analytical wavelengths was investigated and the comparison of computation results between AKC method (the matrix representation of Beer-Lambert's Law) and ...

THE DETERMINATION OF STANDARD ELECTROMOTIVE FORCE OF CELL Cu vertical bar CuSO4 vertical bar Hg2SO4-Hg AT DIFFERENT TEMPERATURES

The emfs of Cu|CuSO_4|Hg_2SO_4-Hg were determined at 5 temperature points from 278.15K to 313.15K. Based on the Pitzer' s Equation a polynomial approximation for the determination of standard emf, E_m, was proposed. The values of E_m obtained by author's method agree with values of E_m obtained by the extended Debye-Huckel equation within experimental errors. Compared with the extrapolation result of extended Debye-Huckel equation, the uncertainty by the selecting of parameter of ion size was avoided.By the...

Molecular determination of oxytetracycline-resistant bacteria and their resistance genes from mariculture environments of China

Aims: To assess the diversity of antibiotic-resistant bacteria and their resistance genes in typical maricultural environments. Methods nand Results: Multidrug-resistant bacteria and resistance genes from a mariculture farm of China were analysed via cultivation and polymerase chain reaction (PCR) methods. Oxytetracycline (OTC)-resistant bacteria were abundant in both abalone and turbot rearing waters, accounting for 3.7% and 9.9% of the culturable microbes. Multidrug resistance was common, with simultaneous resistance to OTC, chloramphenicol and ampicillin the most common resistance phenotype. 16S rDNA sequence analyses indicate that the typical resistant isolates belonged to marine Vibrio, Pseudoalteromonas or Alteromonas species, with resistance most common in Vibrio splendidus isolates. For OTC resistance, tet(A), tet(B) and tet(M) genes were detected in some multidrug-resistant isolates, with tet(D) being the most common molecular determinant. For chloramphenicol resistance, cat II was common, and floR was also detected, especially in marine Pseudoalteromonas strains. Conclusions: There is the risk of multidrug-resistant bacteria contamination in mariculture environments and marine Vibrio and Pseudoalteromonas species serve as reservoirs of specific antibiotic resistance determinants. Significance and Impact of the Study: This paper and similar findings from Korea and Japan indicate the potential for widespread distribution of antibiotic resistance genes in mariculture environments from the East Asian region of the world.

Cadmium toxicity to embryonic-larval development and survival in red sea bream Pagrus major

At 18 degrees C and 33 psu, 24 and 48 h LC50 values of cadmium (Cd) for red sea bream Pagrus major embryos were 9.8 and 6.6 mg l(-1), respectively, while 24,48, 72, and 96 h LC50 values for larvae were 18.9,16.2, 8.0, and 5.6 mg l(-1), respectively, indicating that embryos were more sensitive to Cd toxicity than larvae. Cd concentrations at >= 0.8 mg l(-1) led to low hatchability (0-90% in >= 0.8 mg l(-1) solutions vs. 97-100% in lower ones), delay in time to hatch, high mortality (38-100% vs. 1-10%), morphological abnormality (42-100% vs. 1-10%), reduced length (3.55-3.60 vs. 3.71-3.72 mm) in the embryos and larvae. They were Cd concentration dependent and potential biological significant endpoints for assessing the risk of Cd to aquatic organisms. Heart beat and yolk absorption of the larvae were significantly inhibited at some high concentrations but they were not as sensitive as other endpoints to Cd exposure. (C) 2008 Elsevier Inc. All rights reserved.

Alteration of metallothionein mRNA in bay scallop Argopecten irradians under cadmium exposure and bacteria challenge

Metallothionein (MT) is a superfamily of cysteine-rich proteins contributing to metal metabolism, detoxification of heavy metals, and immune response such as protecting against ionizing radiation and antioxidant defense. A metallothionein (designated AiMT2) gene was identified and cloned from bay scallop, Argopecten irradians. The full length cDNA of AiMT2 consisted of an open reading frame (ORF) of 333 bp encoding a protein of 110 amino acids. with nine characteristic Cys-X-Cys, five Cys-X-X-Cys, five Cys-X-X-X-Cys and two Cys-Cys motif arrangements and a conserved structural pattern Cys-x-Cys-x(3)-Cys-Tyr-x(3)Cys-x-Cys-x(3)-Cys-x-Cys-Arg at the C-terminus. The cloned ANT showed about 50% identity in the deduced amino acid sequence with previously published MT sequences of mussels and oysters. The conserved structural pattern and the close phylogenetic relationship of AiMT2 shared with MTs from other mollusc especially bivalves indicated that AiMT2 was a new member of molluscan MT family. The mRNA transcripts in hemolymph of AiMT2 under cadmium (Cd) exposure and bacteria challenge were examined by real-time RT-PCR. The mRNA expression of AiMT2 was up-regulated to 3.99-fold at 2 h after Listonella anguillarum challenge, and increased drastically to 66.12-fold and 126.96-fold at 16 and 32 h post-challenge respectively. Cadmium ion exposure could induce the expression of AiMT2, and the expression level increased 2.56-fold and 6.91-fold in hemolymph respectively after a 10-day exposure of 100 mu g L-1 and 200 mu g L-1 CdCl2. The sensitivity of AiMT2 to bacteria challenge and cadmium stress indicated it was a new Cd-dependent MT in bay scallop and also regulated by an immune challenge. The changes in the expression of AiMT2 could be used as an indicator of exposure to metals in pollution monitoring programs and oxidative stress, and bay scallop as a potential sentinel organism for the cadmium contamination in aquatic environment. (C) 2008 Elsevier Inc. All rights reserved.

beta-catenin in early development of the lancelet embryo indicates specific determination of embryonic polarity

The lancelet (amphioxus) embryo develops from a miolecithal egg and starts gastrulation when it is approximately 400 cells in size, in a fashion similar to that of some non-chordate deuterostomes. Throughout this type of gastrulation, the embryo develops characteristics such as the notochord and hollow nerve cord that commonly appear in chordates. beta-Catenin is an important factor in initiating body patterning. The behavior and developmental pattern of this protein in early lancelet development was examined in this study. Cytoplasmic beta-catenin was localized to the animal pole after fertilization and then was incorporated asymmetrically into the blastomeres during the first cleavage. Asymmetric distribution was observed at least until the 32-cell stage. The first nuclear localization was at the 64-cell stage, and involved all of the cells. At the initial gastrula stage, however, concentrated beta-catenin was found on the dorsal side. LiCl treatment affected the asymmetric pattern of beta-catenin during the first cleavage. LiCl also changed distribution of nuclear beta-catenin at the initial gastrula stage: distribution extended to cells on the animal side. Apparently associated with this change, expression domains of goosecoid, lhx3 and otx also changed to a radially symmetric pattern centered at the animal pole. However, LiCl-treated embryos were able to establish embryonic polarity. The present study suggests that in the lancelet embryo, polarity determination is independent of dorsal morphogenesis.

Evaluation of 28 marine algae from the Qingdao coast for antioxidative capacity and determination of antioxidant efficiency and total phenolic content of fractions and subfractions derived from Symphyocladia latiuscula (Rhodomelaceae)

The extracts obtained from 28 species of marine algae were evaluated for their antioxidant activity (AA) versus the positive controls butylated hydroxytoluene (BHT), gallic acid (GA), and ascorbic acid (AscA). Most of the tested samples displayed antioxidant activity to various degrees. Among them, the extract of Symphyocladia latiuscula exhibited the strongest AA, which was comparable to BHT, GA, and AscA in radical scavenging activity, as shown in the DPPH (alpha,alpha-diphenyl-beta-picrylhydrazyl) assay, and higher than those of the positive controls in beta-carotene-linoleate assay system. In addition, the ethyl acetate-soluble fraction isolated from the crude extract of S. latiuscula exhibited the highest antioxidant activity in both assay systems. This fraction was further fractionated into seven subfractions (F1-F7) by vacuum liquid chromatography (VLC). F1 and F4 were found to be the most effective subfractions in scavenging DPPH radical assay and in the beta-carotene-linoleate assay, respectively. The total phenolic content (TPC) and reducing power (RP) for all of the extracts, fractions, and subfractions (F1-F7) were also determined. The TPC of the 28 extracts ranged from 0.10 to 8.00 gallic acid equivalents (mg/g seaweed dry weight) while the RP ranged from 0.07 to 11.60 ascorbic acid equivalents (mg center dot g(-1) seaweed dry weight). Highly positive relationships between AA and TPC as well as between AA and RP were found for the extracts and fractions, while for the subfractions F1-F7 only weak or no such relations were found. The results obtained from this study indicate that further analysis is needed of those marine algal species that contain the most antioxidant activity in order to identify the active principles.

Simultaneous determination of four phases of copper in geological samples

According to the specific property of respective phases in copper ore, optimal extracting condition for, tour phases of copper with five infusion was examined. After a series of experiments, for example, different weight Of sample, artificial mixed single phases sample and repeated experiment, the extracting ratio constants foil all phases in different infusions were obtained. The mathematical model which is on the basis of the stable extracting constant is established. Based on the purpose-control genetic algorithms, we only need to determine the total copper in the sample in different infusions under the selected condition, then the value of respective phase could be calculated. The-relative standard deviation are (%) free oxidized copper phase:1.5, conjunction oxidized copper phase: 17.6,, secondary copper sulfide phase: 1.9, primary copper sulfide phase : 2.7,total copper: 0.8.

Determination of multiple trace elements in seawater using chelation ion chromatography and ICP-MS

An off-line chelation system combined with ICP-MS technique was developed for the quantitative determination of trace elements in seawater, namely V, Co, Ni, Cu, Zn, Mo, Cd, Pb, U and rare earth elements(REEs). The system was built based on an ion chromatography equipped with MetPac((R)) CC-I chelation columns which had a strong selective chelation to these target elements within a pH range 5.2-5.6. Acidified seawater samples and NH4Ac(2 mol/L) were blended to meet suitable pH before being injected into the chelation column, thus target elements were retained while alkali and alkaline metals were excluded. Then chelated elements were eluted by HNO3 (1 mol/L) and samples were collected for ICP-MS analysis. Varying the ratio of input( gen. 200 mL) to output( gen. 5 mL), the target elements which were concentrated as 40 times as their concentrations were far beyond instrumental quantification limits. At last, a certificated seawater CASS-4 was introduced and our detected values were in good agreement with those certified values.

Determination of fractional energy loss of waves in nearshore waters using an improved high-order Boussinesq-type model

Fractional energy losses of waves due to wave breaking when passing over a submerged bar are studied systematically using a modified numerical code that is based on the high-order Boussinesq-type equations. The model is first tested by the additional experimental data, and the model's capability of simulating the wave transformation over both gentle slope and steep slope is demonstrated. Then, the model's breaking index is replaced and tested. The new breaking index, which is optimized from the several breaking indices, is not sensitive to the spatial grid length and includes the bottom slopes. Numerical tests show that the modified model with the new breaking index is more stable and efficient for the shallow-water wave breaking. Finally, the modified model is used to study the fractional energy losses for the regular waves propagating and breaking over a submerged bar. Our results have revealed that how the nonlinearity and the dispersion of the incident waves as well as the dimensionless bar height (normalized by water depth) dominate the fractional energy losses. It is also found that the bar slope (limited to gentle slopes that less than 1:10) and the dimensionless bar length (normalized by incident wave length) have negligible effects on the fractional energy losses.

Determination of Total Arsenic and Arsenic Metabolites in Human Liver Hepatocytes

The effects of direct sampling and three digestion methods were investigated on the determination of arsenic in Chang liver hepatocytes after ultrasonic disintegration were investigated. The results showed that the efficiency of microwave digestion and obturator digestion was better than cold digestion and direct sampling. The day precision (present as RSD) of microwave digestion and obturator digestion were 2.1% and 1.2% the inter-day precision were 1.2% and 2.0%, respectively. The spike recovery for the total As in the sample is 95.7% - 108.1%. The As detection limits with these four sample treatment methods (including direct sampling) were 0.74 - 0.93 mu g/L. In addition, arsenic speciation in Chang liver hepatocytes was also analyzed using the hyphenated technique of high performance liquid chromatography coupled with inductively coupled plasma-mass spectrometry. The experimental results indicated that dimethylarsinic acid (DMA) and an intermediate metabolite of DMA were found lit Chang liver hepatocytes besides inorganic arsenic (As(III) and As(V)).