AN EXPERT SYSTEM FOR SOLVENT-EXTRACTION OF RARE-EARTHS

An expert system for solvent extraction of rare earths has been developed using LISP. The goal of this project was to mimic the chemists' inferential abilities to assist in the process of solvent extraction of rare earths. The system includes frequently used extractants, separation of specific rare earths, recommendation of procedures for the separation of mixtures of rare earths using (2-ethylhexyl)phosphonic acid 2-ethylhexyl monoester, selection of parameters for counter-current extraction and methods for evaluation of the technique, and the economics of the processing. The expert system runs on an IBM-PC/XT.

CYCLIC VOLTAMMETRIC AND SPECTROELECTROCHEMICAL STUDIES OF COPPER IN ALKALINE-SOLUTION

The behaviour of the electroplated copper film electrode on tin oxide/glass or glassy carbon surface was studied in potassium hydroxide medium by cyclic voltammetry and in situ transmission spectroelectrochemistry. The results indicate that the electroplated copper film electrode is similar to a copper electrode and cyclic voltammetry with this electrode affords more resolution. The anodic peaks were found to correspond successively to the adsorption of oxygen, the formation of a surface layer of Cu2O, the formation of a surface layer of Cu(OH)2 or CuO and formation of a thick multilayer film of CuO. This is the first time it has been proposed that a surface layer of Cu(OH)2 or CuO is formed from the oxidation of the surface layer of Cu2O. Similarly, a clear interpretation is presented that the cathodic peaks correspond successively to the reduction of CuO to Cu2O, the reductions of Cu2O to Cu and the soluble Cu(II) species to Cu. On the other hand, a shoulder peak related to the chemical transformation of Cu(OH)2 to CuO was first observed.

INVESTIGATION ON THE LUMINESCENCE PROPERTIES OF DY-3+ AND EU-3+ IN ALKALINE-EARTH BORATES

In this paper, the yellow-to-blue intensity ratio of Dy3+ (Y/B) and the red-to-orange intensity ratio of Eu3+ (R/O) were studied in relation to the compositions and structures of alkaline-earth borates. The dependence of the energy of the Eu3+ charge-transfer band (CTB) and of the emission intensity of Dy3+ on the alkaline-earth ions and the boron content of the hosts is discussed.

STUDIES ON THE REACTION AND STRUCTURE OF THE COMPLEXES OF ALKALINE-EARTH METAL WITH CHLOROPHOSPHONAZO-DBC

In this paper, the reaction and structure of the complexes of alkaline earth metal (Ca, Sr, Ba) with 2-(4'-chloro-2'-phosphonazo)-7-(2', 6'-dibromo-4'-chlorophenylazo 1, 8-dihydroxy-3, 6-naphthalene disulfonic acid (Chlorophosphonazo-DBC) have been studied. This ligand has eight forms under different acidity. The protonation reactions take place at [H+] > 0.36 mol.dm-3. The ligand begins dissociations at pH > 0.5. Two protons are released in the complexes formation reactions(Me2+ + 2HI half-arrow-pointing-left and half-arrow-pointing-right MeL2 + 2H+). The stability constants of the complexes of Calcium, Strontium and Barium have been determined by Yoe-Jone method, Majumder-Chakrabartty method and calculation method. The order of the stability of complexes is as follows: Sr > Ba > Ca. The structure of the complexes have also been studied by infrared spectroscopy, Laser Raman spectroscopy, NMR, and EPR. The results show that these groups of N = N, PO3H2 and OH are active groups in the complex reactions. The structure of the complexes of Strontium, Barium and Calcium with chlorophosphonazo-DBC are represented and the reaction and the complex bonds are discussed in this paper.

GENERAL ALPHA-N INDEX AND ITS APPLICATION .1. GENERAL ALPHA-N INDEX AND ITS APPLICATION IN THE EXTRACTION OF Y, CE, U, AND TH BY NEUTRAL PHOSPHORUS EXTRACTANCTS

The general a(N) index is established for molecules containing heteroatoms, rings, and multiple bonds. The general a(N) index is able to describe molecules with minute differences in structure and can also reveal the properties of molecules. This theory is successfully applied to the case of neutral phosphorus extractants. Both the molecular polarity and steric effect are characterized by the general a(N) index. The relationships between these properties and the distribution ratios for extracting Y, Ce, U, and Th are also shown by the general a(N) index.

Extraction behavior of Mo and W as homologs of Sg with α-benzoinoxime

Solvent extraction of molybdenum and tungsten as homologues of Sg with a-benzoinoxime from HCl solutions has been investigated. The extraction equilibration was achieved at 20s for Mo and W. Molybdenum was almost quantitatively extracted from 0.001 to 4M HCl solutions, and the extraction yields decreased at higher and lower acid concentrations due to the formation of anionic oxychloride complex and anionic species MO42-, respectively. The extraction yield of W was lower than that of Mo during the whole range of acid concentration. The composition of the extracted species was determined by using the slope method in present experiment. The elemental analysis, IR and 1H NMR spectra of the extracted species suggest that the extracted complex contain one MoO22+or WO22+ groups bonded with two a-benzoinoxime molecules.

A simple method for DNA extraction from sporophyte in the brown alga Laminaria japonica

A simple method was developed for extracting DNA from brown algae Laminaria japonica, which possess large amounts of acidic polysaccharides. Firstly, the sporophyte were washed by eliminating polysaccaride buffer to remove the polysaccharides and then ground in liquid nitrogen. Secondly, the powders were treated with lysing buffer. Thirdly, KAc was used to eliminate the remaining acidic polysaccharides. The extracted DNA was purified using a chloroform-isoamyl alcohol ( 24: 1 v/v), and precipitated in cold isopropanol. The yield was from 18.7 to 37.5 mu g g(-1) (wet weight) and the purity of total DNA was determined spectrophotometrically as the ratio of A(260)/A(280), which was about 1.7 - 1.9. The extracted DNA was of high quality and suitable for molecular analyses, such as PCR, restriction enzyme digestion. This method is a reproducible, simple, and rapid technique for routine DNA extraction from sporophyte in Laminaria japonica. Furthermore, the low cost of this method makes it attractive for large-scale studies.

A novel polypeptide from shark cartilage with potent anti-angiogenic activity

Using guanidine-HCl extraction, acetone precipitation, ultra-filtration and chromatography, a novel polypeptide with potent anti-angiogenic activity was purified from cartilage of the shark, Prionace glauca. N-terminal amino acid sequence analysis and SDS-PAGE revealed that the substance is a novel polypeptide with MW 15500 (PG155). The anti-angiogenic effects of PG155 were evaluated using zebrafish embryos model in vivo. Treatment of the embryos with 20 mu g/ml PG155 resulted in a significant reduction in the growth of subintestinal vessels (SIVs). A higher dose resulted in almost complete inhibition of SIV growth, as observed by endogenous alkaline phosphatase (EAP) staining assay. An in vitro transwell experiment revealed that the polypeptide inhibited vascular endothelial growth factor (VEGF) induced migration and tubulogenesis of human umbilical vein endothelial cells (HUVECs). Exposure of HUVECs in 20 mu g/ml PG155 significantly decreased the density of migrated cells. Almost complete inhibition of cell migration was found when HUVECs were treated with 40-80 mu g/ml PG155. PG155 (20 mu g/ml) markedly inhibited the tube formation of HUVECs and a dose-dependent effect was also found when treatment of HUVECs with PG155 at the concentration from 20 to 160 mu g/ml.

Digestive gut structure and activity of protease, amylase, and alkaline phosphatase in Calanus sinicus during summer in the Yellow Sea and the East China Sea

Calanus sinicus aggregate at the depth of 40-60 m (ambient temperature is 16 degreesC) in the waters of the continental shelf of the Yellow Sea during summer. in animals found in near shore regions, there are changes in digestive gut cells structure, digestive enzyme activity (protease, amylase), and tissue enzyme (alkaline phosphatase (ALP)), which may represent adaptations by this cold-water animal to a sharp seasonal increase in temperature of 6-23 degreesC. The activities of the digestive enzymes (protease and amylase) are very low in animals at stations near the estuary of Yangtse River, whereas they are relatively high in animals at stations in the central Yellow Sea, During summer, B-cells of the intestine and the villi intestinalis disappear in animals that do not feed at stations near the estuary of the Yangtse River. Respiration rates were undetectable or quite low during summer in C. sinicus from stations near the estuary of the Yangtse River, whereas they were relatively high at stations in the central Yellow Sea. Based upon the morphological characteristics of the digestive gut structure, enzyme levels, respiration rates, and the distribution of C. sinicus, we concluded that C. sinicus might be dormant during summer in the near shore areas of the East China Sea while remaining active in the central Yellow Sea. (C) 2002 Elsevier Science B.V. All rights reserved.

Extraction of phosphorus in natural waters and sediments by ignition method

Phosphorus recoveries from selected inorganic and organic P-containing compounds after ignition with auxiliaries, such as MgSO4, Mg (NO3)(2), MgCl2, Mg (Ac)(2) and CaCl2 were studied. It was found that the phosphorus could not be completely recovered when most P-containing compounds were ignited with MgSO4 at temperature not higher than 500degreesC if the baked residue was extracted with 0.2 mol/L HCl for 30 min at 80degreesC or at room temperature. In contrast, MgCl2, Mg(Ac)(2) and CaCl2, as well as Mg(NO3)(2), could all yield complete P recoveries. We suggest that MgCl2 rather than MgSO4, which is usually used, should be utilized as ashing auxiliary agent in the P extraction by ignition method. Although Mg (NO3)(2) is a highly effective auxiliary agent, yet interference from MgSO4, danger of explosion, toxicity of nitrogen dioxide and more manipulation steps may limit its widespread utilization. It is suggested that if sediment is ignited with MgCl2, the extraction of residue with 0.2 mol/L HCl for 30 min at 80degreesC could give good result.

An efficient combination of supercritical fluid extraction and high-speed counter-current chromatography to extract and purify homoisoflavonoids from Ophiopogon japonicus (Thunb.) Ker-Gawler

Supercritical fluid extraction (SFE) was used to extract homoisoflavonoids from Ophiopogon japonicus (Thunb.) Ker-Gawler. The optimization of parameters was carried out using an orthogonal test L-9 (3)(4) including pressure, temperature, dynamic extraction time and the amount of modifier. The process was then scaled up by 100 times with a preparative SFE system under the optimized conditions of 25 MPa, 55 degrees C, 4.0 h and 25% methanol as a modifier. Then crude extracts were separated and purified by high-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of n-hexane/ethyl acetate/methanol/ACN/water (1.8:1.0:1.0:1.2:1.0 v/v). There three homoisoflavonoidal compounds including methylophiopogonanone A 6-aldehydo-isoophiopogonone A, and 6-formyl-isoophiopogonanone A, were successfully isolated and purified in one step. The collected fractions were analyzed by HPLC. In each operation, 140 mg crude extracts was separated and yielded 15.3 mg of methylophiopogonanone A (96.9% purity), 4.1 mg of 6-aldehydo-isoophiopogonone A (98.3% purity) and 13.5 mg of 6-formyl-isoophiopogonanone A (97.3% purity) respectively. The chemical structure of the three homoisoflavonoids are identified by means of ESI-MS and NMR analysis.

Study on extraction of agaropectin from Gelidium amansii and its anticoagulant activity

Gelidium amansii agar was fractionated on DEAE-cellulose and four fractions were obtained sequentially. The yields of 1.0 mol/L NaCl fraction and 2.5 mol/L NaCl fraction were 2.80% and 2.03%. They are highly sulfated agar, and named as agaropectin with sulfate content being 22.8% and 32.5%, respectively. The anticoagulant experiment results show that agaropectin could effectively prolong the coagulation time in a dose-dependent manner in vitro. Agaropection could be absorbed and effectively prolong the plasma coagulation time in vivo. After intragastric administration at the doses of 100, 200, and 400 mg/kg.d in rats for 15 days, TT (thrombin time), CT (coagulation time), PT (prothrombin time), and APTT (activated partial thromboplastin time) could be effectively prolonged and the plasma Fib level could be significantly lowered.

The extraction of pigments from fresh Laminaria japonica

The pigments in Laminaria japonica was extracted with six organic solvents and analyzed in spectroscopy analysis. The extractions conditions were screened by an orthogonal test and the quantity of extracted pigments was determined spectroscopically. The results show that: (1) among the six organic solvents, acetone was the most effective one for the extraction; (2) the optimum extraction conditions were as follows: the ratio of S/M (solvent volume/ material weight) was 30 ml/g; fresh seaweed was extracted 2 times in 2 h; (3) the average total content of pigments was 1.85 mg/g (calculated with dry L. japonica).

Extraction of the polysaccharides from five algae and their potential antioxidant activity in vitro

The sulfated polysaccharides extracted from algae possess excellent antioxidant activities. In this study, we prepared five polysaccharides extracted from five algae including one brown alga Laminaria japonica. one red alga Porphyra haitanensis and three green algae Ulva pertusa, Enteromorpha linza and Bryopsis plumose. And then the antioxidant activities of all the samples were investigated including scavenging effects of superoxide and hydroxyl radicals, and reducing power. The chemical analysis and FT-IR spectrum showed these extracts were polysaccharides. And in addition, we found that certain polysaccharide exhibited stronger antioxidant activity in certain antioxidant activity. Factors effecting and attributing to radical scavenging effect need to be further studied. (C) 2010 Elsevier Ltd. All rights reserved.