The existed gob-areas such as roadway, goaf, headway and stope are of various sizes and shapes. These gob-areas are one of the main hazard which threatens mine production security. Metal gob-areas characteristics: gob-areas are not filled fully, mostly filled with water, or partly drop down, rock formation mostly have large dips. We present a converted shear waves method to detect the gob-areas in metal mines. The experimental results in Qidashan open pit iron mine show proposed method is suitable for positioning cavity without affecting excavation and transportation. Accurate rate of research results achieves 90%. This research plays a leading role in preventing geological hazards, provides reliable and detailed geological basis for mining process so as to guarantee the high production rate and high efficiency for metal mines.

A simple and sensitive cloud point extraction high-performance liquid chromatography method is proposed for the determination of isoniazid in blood. The procedure is based on the product of the reaction of isoniazid with benzaldehyde. It can be validated that there is a linear relationship between the signal of isonicotinyl hydrazone and the concentration of isoniazid. A cloud point extraction system of nonionic surfactant Triton X-100 is applied for preconcentration of isonicotinyl hydrazone. Then the analytes in surfactant-rich phase are detected with HPLC-UV system. calibration graph was obtained in the range of 2.0 × 10(-3)-0.5 mg/L, the detection limit was 5.0 × 10(-4) mg/L. Method validation is performed on serum samples spiked at two levels, the recoveries ranging from 82.17-83.81%, with relative standard deviations from 2.45% to 3.89%.

A new method for the determination of nine organophosphorus pesticides (OPPs): Dichlorvos, methamidophos, acephate, diazinon, dimethoate, chlorpyrifos, parathion-methyl, malathion and parathion-ethyl in concentrated fruit juice was developed using the cloud point extraction coupled with ultrasonic-assisted back-extraction prior to gas chromatography with flame photometric detection (GC-FPD) analysis. The parameters and variables that affect the extraction were investigated. Under optimum conditions: a solution containing 6% (W/V) polyethylene glycol 6000 (PEG 6000) and 20% (W/V) Na(2)SO(4) for the extraction of the OPPs. The coacervation phase obtained was back extracted with ethyl acetate. The upper ethyl acetate solution was centrifugated simply for further cleanup for the sake of automatic injection. A preconcentration factor of 50 was obtained for these nine pesticides. Using this method, the limits of detection (LOD) and limits of quantification (LOQ) were in the range of 0.5-3.0 and 1.5-9.0μgkg(-1) in concentrated fruit juice, respectively; the relative standard deviations (RSD) were <9%.

Melamine shows a polarographic wave at-0.34 V(vs.SCE) in a solution of KOH-Na2SO3,and the second derivative peak current of the wave is linearly proportional to the melamine concentration in the range from 1.0×10-2 to 10.0 mg/L(r=0.9992).Melamine in milk samples can not be directly determined by the polarographic method because of the interference of colloidal protein in milk.In this paper,many methods were studied for dispelling the interference.When the concentration of NaCl in milk was 150 g/L and the solution was kept at 100 ℃ for 10 min,the interference of colloidal protein could be avoided.In the case,the linear sweep polarographic method could be used for the determination of melamine in milk.The peak current was linearly proportional to the melamine concentration in the range of 0.4～10.0 mg/L with the detection limit of 0.1 mg/L.The recoveries were between 78.2% and 92.5%.The whole determination procedure could be completed in 20 min.

Carbofuran can be hydrolysed to from 2,3-dihydro-2,2-dimethyl-7-benzofuranol (BF). BF is coupled with 4-aminoantipyrene (AP) in presence of potassium ferricyanide (K3Fe(CN)6) to generate red coloured derivative(BFAP)having λmax 530nm. Cloud point extraction (CPE) methodology and using surfactant Triton X-100 as extractant was applied as a preconcentration step prior to HPLC, the surfactant-rich phase containing BFAP was then analysed by HPLC in visible region. The high back ground absorbance of Triton X-100 in UV region was completely avoided. A new visible detection method with high-performance liquid chromatography (HPLC) has been developed for the determination of carbofuran. Using this method, we found that carbofuran residues could be determined with recoveries ranging from 80.4% to 84.5%, relative standard deviations in the range of 2.51–3.26% for three fortified rice levels, and the limit of detection as 5.0×10−4cJ/cK.

Sonic wave dispersion characteristics are one of the most important targets of study, particularly in estimating shear wave velocity from borehole sonic logging. We have tested dispersion characteristics using monopole and dipole sources. Theoretical dispersion curves were computed for tool-absent and tool-included models having the same physical properties but different diameters ( including Phi 520 mm, Phi 150 mm, and Phi 76 mm). Comparisons were made between boreholes of different sizes and between tool-absent and tool-included models. Between the tool-included and the tool-absent boreholes, a close similarity in dispersion curve shape was revealed for the monopole source, and a significant difference was shown for the dipole source. However, for the cut-off frequency, particularly in the engineering boreholes (Phi 76 mm and Phi 50 mm), a significant difference was observed for signals from the monopole source, but approximately the same cut-off frequencies were found with the dipole source. This indicates the need of careful choice of source frequency in monopole-source sonic logging, particularly in an engineering borehole.The results of numerical experiments show that cut-off frequency is exponentially proportional to the inverse of borehole radius, irrespective of the mode type and the presence of a tool, and that the cut-off frequencies for each borehole environment could be expressed as an exponential function, rather than the inversely proportional relationship between the cut-off frequency and the borehole radius that was previously generally recognised. From the direct comparison of dispersion curves, the effects on the dispersion characteristics of borehole size and the presence of the tool can be revealed more clearly than in previous studies, which presented the dispersion curve and/or characteristics for each borehole environment separately.

Isoniazid (INH) reacted with p-dimethylaminobenzaldehyde (DABD) in the presence of trichloroacetic acid to give isonicotinylhydrazone (INZ) having λmax 365nm. Cloud point extraction (CPE) is carried out to extract INH and IHZ in aqueous solutions using surfactant poly(ethylene glycol) 4000 (PEG4000), respectively. Langmuir model is used to study the adsorption behaviors of the two solutes on micelles of PEG4000. A linear correlation is found between variation of PEG4000 concentration required for feed concentration of the two solutes and used to predict PEG4000 concentration required for extracting INH and IHZ in CPE procedure. The results calculated show that, for a desired recovery level of 90%, only can IHZ be sufficiently extracted by PEG4000. In this experiment, the feed concentration of PEG4000 is defined by above-mentioned correlation, and the effects of other operating parameters, e.g., concentration of salt, pH and centrifugation time on extraction of PEG4000-IHZ system have also been studied in detail. The proposed CPE method coupled with HPLC-UV system is successfully used for the determination of INH in urine sample.

The polarographic catalytic wave of the thiram and Cu2+ in tartaric acid, potassium sodium tartrate and persulfate systerm was used for the determination of tniram. In 0.1 mol/L C4H6O6-C4H4O6KNa (pH = 5.5) + 3.0 x 10(-3) mol/L K2S2O8 + 4.0 x 10(-6) mol/L Cu2+ base solution, the peak potential of the polarographic catalytic wave was set at -0.8 V (vs. SCE), and the second derivative peak current of the catalytic wave was linearly proportional to the thiram concentration in the range of 1.0 x 10(-8) - 1.0 x 10(-6) mol/L (r = 0.9994). The detection limit was 2.0 x 10(-9) mol/L. The relative standard deviations was 1.2% (n = 10). The reductive peak current of thriam was 12 nA, and the corresponding catalytic current was 1.5 x 10(3) nA. Thus the sensitivity of the catalytic wave of thiram was 125 times higher than that of the corresponding reduction wave. The recovery was between 83.8% and 91.4%. The method is sensitive, simple and rapid.

A derivatization polarographic method was developed for the determination of trichlorfon in vegetables. The trichlorfon was hydrolyzed into dimethyl phosphate and dichloroacetaldehyde, and then the hydrazone was formed from the reaction of dichloroacetaldehyde with phenylhydrazine. A sensitive second derivation voltammetry wave of the hydrazone was obtained at -784 mV (vs. SCE) by single sweep oscilloplolarography. The sensitivity to hydrazone is 200 times larger than that to trichlorfom in optimum conditions. The peak current is proportional to the concentration of trichlorfon over the range of 1.6 - 83 mu g/L (r = 0.9912), and the limit of detection is 0.55 mu g/L. This method has been used for the determination of trichlorfon in vegetables due to its simpletiy, reliableieity and rapidity.

Investigations of certification agencies were conducted in four Chinese cities: Guangzhou, Shenzhen, Hangzhou and Qingdao. Based on an analysis of the data and information obtained, the status and character of agro-food certification in China were assessed. The main obstacle for development of agro-food certification was identified as the lack of market acceptance for it. In conclusion, the paper provides some suggestions for improving agro-food certification in China.

<正>开展第三方认证被广泛视为提高产品品质和声誉、增强竞争力的有效手段之一。无公害农产品、绿色食品和有机食品认证是当前我国农产品质量安全第三方认证3种基本的产品认证类型。近年来,这3种产品认证都有不同程度的发展,并各自取得了可喜的成效。

A CPE-HPLC (UV) method was developed for the determination of Sudan (I-IV) dyes, non-ionic surfactant Triton X-100 was used to extract and preconcentrate Sudan dyes from chilli powder prior to their determination by HPLC-UV. The separation and determination of Sudan dyes was then carried out in the HPLC-UV system with isocratic elution, and the detector was set at 500 nm. The parameters and variables that affect the extraction were investigated. Under optimum conditions: 3% of Triton X-100 (W/V), 10% of Na2CO3 (W/V), heat-assisted at 70 degrees C for 30 min. Recoveries of the Sudan dyes ranged from 80.70% to 85.45% in chilli powder by CPE method, with all the relative standard deviations of less than 3%. Limit of detection (LOD) and limit of quantification (LOQ) were in the range of 2.0-4.0 and 7.0-12.0 microg kg(-1) in chilli powder, respectively.