[Research of the certified reference material of mecury in lyophilized bovine blood].

Objective: To develop a reference material for the analysis of mercury in freeze-dried bovine blood. Methods: The whole blood of the bovine was collected, mercury standard solution was added, After mixing, packaging and freeze-drying. Two concentration levels of reference materials were prepared. The homogeneity and stability were evaluated by t-test and F-test methods respectively. The uncertainty in preparation, long-term stability, short-term stability and fixed value were evaluated Evaluation and assignment of reference materials. The research products were fixed value and were analyzed by two methods and fixed value in 9 laboratories and the uncertainty during development was analyzed. Results: The reference material has good uniformity and can be kept stably for 12 months at -20 ℃; When transported at ≤35 ℃, the quantity value is stable within 7 days; After re dissolution, it can be stored at 4 ℃ for 5 days; The values are 9.4 respectively µg/L and 29.2 µg/L, and the uncertainty is ±1.1 respectively µg/L and ±2.3 µg/L (k=2) . Conclusion: The indexes of reference materials for mercury composition analysis in freeze-dried bovine blood meet the requirements of technical specifications and have certain application value.

[Development of the certified reference material of cadmium in human urine (freeze-dried)].

Objective: To develop the certified reference material of cadmium in human urine (freeze-dried) . Methods: Urine were collected from normal human, and then the urine samples were prepared by adding standard, mixing, packing and freeze-drying. After homogeneity test and stability test, the urine samples were determined by two methods in seven independent laboratories, the uncertainty of the certified reference material was evaluated. Results: Take at least 0.20 ml solution of the certified reference material per use, and the homogeneity is good. The freeze-dried materials can be kept stable for 12 months at ≤4 °C, and the re-dissolved reference materials can be stabilized for 7 days at 4 °C. The standard values and uncertainty of the two levels were (5.34±0.34) µg/L and (15.47±0.72) µg/L, respectively. Conclusion: The standards met the requirements of national standards, and can be used to verify the methods of detecting cadmium in human urine and to detect the samples.

[Analysis on occupational health laboratories' proficiency testing program for determination of bovine blood lead and urinary cadmium].

Objective: To analyze the results obtained from the proficiency testing program for determination of bovine blood lead and urinary cadmium, so as to evaluate the proficiency of the laboratories, and improve the detection and quality control capability of occapational health laboratory. Methods: Prepared 3 levels of lead samples with bovine blood as base material, taking Technical Norm of Primary Reference Material as Operating standard, 60, 80, 180 µg/L were used as the standard concentration. All samples were made for 200 bottles. Normal urine were used to prepared 3 levels of cadmium samples with 5.0, 7.0, 10.0 µg/L as standard concentration, then 3 level of samples were made for 200 bottles respectively. Blood lead and urinary cadmium samples were sent to each laboratory in the form of sample pairs. One-way ANOVA was used to investigate the homogeneity. The results of each laboratory were statistically analyzed by robust statistical method, and the detection ability of the laboratory was evaluated by the Z ratio score method. By consulting the test reports and original records of each participating laboratory, the reasons for the unsatisfactory results were analyzed. Results: The statistical F of the uniformity of blood lead 1.42, 1.37 and 2.85, F<3.13, P were 0.294, 0.314 and 0.059, respectively in 31 labs. There is no statistical significance in the difference of blood lead (P>0.05). And urine cadmium was less than the critical value (P>0.05). In all, 31 laboratories participated in the test of blood lead, and 28 loboratories paticipated in urine cadmium verification. The statistical F of the uniformity of urinary cadmium 1.90, 1.35 and 1.19, F<3.13. The homogeneity of the samples were in accordance with the requirements of proficiency testing program. The satisfactory rate of the results for blood lead was 84% (26/31) , and the satisfactory rate of urinary cadmium was 93% (26/28) . In the test of blood lead, 21 of the 31 laboratories were controlled by the standard material method. Totally, 20 of them get an satisfactory level, the rate was 95%. Conclusion: Most of the laboratory test results were satisfactory, which showed that the detection capability for blood lead and urine cadmium was good. The main causes of unsatisfactory results were detection methods, tools of quality control ortraceability standards.

[Analysis of inter-laboratory comparison results of arsenic in urine and explore the influence factors on detection].

Objective: Through inter-laboratory comparison to analysis and evaluation of the detection capacity of arsenic in the urine. Methods: Urine arsenic samples were prepared with normal human urine as matrix. The homogeneity of the samples was investigated and the results were statistically analyzed by single factor analysis of variance. 2 samples were issued to each participant laboratory. A robust statistical four-point distance method was used to calculate the results submitted by each participant laboratory and the test capability of the laboratory was assessed by the z-score method. By means of method experiments and records, the reasons of dissatisfaction and the influencing factors of the results were discussed. Results: The statistic of the homogeneity of urine arsenic samples was less than the critical value (P>0.05) , which showed that the arsenic in the sample was homogeneous. The satisfactory rate of comparison between 36 laboratories was 86.1%. The main reasons for dissatisfaction were the testing conditions and the quality control measures. The selection of sample pretreatment, acidity control and hydrogenation conditions was the main influencing factor for the determination of urinary arsenic by atomic fluorescence spectrometry. Conclusion: The level of urinary arsenic detection in the occupational health laboratories was generally better and a few laboratories need to be improved ability of detection. It was very important to control the test conditions reasonably and strengthen the quality control measures to improve the accuracy of urine arsenic detection.

[Optimization of ion selective electrode method in detection of urinary fluorine].

Objective: To optimize the ion selective electrode method of measuring urinary fluorine in WS/T 30-1996. Methods: The volume of 5 mol/L NaOH solution was fixed to confect the TISAB buffer solution. The samples were prepared by mixing 5 ml urine and equal volume of TISAB solution. Fluorine electrode and calomel electrode was used to test. When the potential value changed less than ±0.5 mV in one minute, it could be recorded. The standard curve method was selected as a quantitive method. Results: The linear range of this method was 0.07~50.0 mg/L, E=238.96-57.50lgC, r=0.999 8. The LOD and LOQ were 0.02 mg/L and 0.07 mg/L (with 5 ml urine) , respectively. The RSD of intra -and inter-batch precision were 0.80%~2.82% and 2.17%~2.86%, respectively. The recovery rate was 102%~107%. The urine sample could be preserved stably for 14 days at room temperature, and for 30 days at 4 ℃ and -20 ℃. Conclusion: In this method, the preparation process of TISAB buffer solution was simplified, and the linear range was expanded. It could meet the needs of occupational population detection.

Accuracy of stress measurement by Laue microdiffraction (Laue-DIC method): the influence of image noise, calibration errors and spot number.

Laue microdiffraction, available at several synchrotron radiation facilities, is well suited for measuring the intragranular stress field in deformed materials thanks to the achievable submicrometer beam size. The traditional method for extracting elastic strain (and hence stress) and lattice orientation from a microdiffraction image relies on fitting each Laue spot with an analytical function to estimate the peak position on the detector screen. The method is thus limited to spots exhibiting ellipsoidal shapes, thereby impeding the study of specimens plastically deformed. To overcome this difficulty, the so-called Laue-DIC method introduces digital image correlation (DIC) for the evaluation of the relative positions of spots, which can thus be of any shape. This paper is dedicated to evaluating the accuracy of this Laue-DIC method. First, a simple image noise model is established and verified on the data acquired at beamline BM32 of the European Synchrotron Radiation Facility. Then, the effect of image noise on errors on spot displacement measured by DIC is evaluated by Monte Carlo simulation. Finally, the combined effect of the image noise, calibration errors and the number of Laue spots used for data treatment is investigated. Results in terms of the uncertainty of stress measurement are provided, and various error regimes are identified.

[A comparison between 3.0 T MRI and histopathology for preoperative T staging of potentially resectable esophageal cancer].

Objective: To explore the value of 3.0 T MRI using multiple sequences (star VIBE+ BLADE) in evaluating the preoperative T staging for potentially resectable esophageal cancer (EC). Methods: Between April 2015 and March 2016, a total of 66 consecutive patients with endoscopically proven resectable EC underwent 3.0T MRI in the Affiliated Cancer Hospital of Zhengzhou University.Two independent readers were assigned a T staging on MRI according to the 7th edition of UICC-AJCC TNM Classification, the results of preoperative T staging were compared and analyzed with post-operative pathologic confirmation. Results: The MRI T staging of two readers were highly consistent with histopathological findings, and the sensitivity, specificity and accuracy of preoperative T staging MR imaging were also very high. Conclusion: 3.0 T MRI using multiple sequences is with high accuracy for patients of potentially resectable EC in T staging. The staging accuracy of T1, T2 and T3 is better than that of T4a. 3.0T MRI using multiple sequences could be used as a noninvasive imaging method for pre-operative T staging of EC.

[Determination of fluorine-ion in human urine by ion chromatography method].

Objective: To establish a method to determine fluorine ion in human urine by ion chromatography method. Methods: The samples were centrifuged, diluted and processed by C(18) solid-phase column, potassium hydroxide as mobile phase, gradient elution, separated by AS(15), and determined by anion conductivity detector. Results: The linear correlation coefficient of fluoride ion in the range of 0.02-10.00 mg/L was more than 0.999. The lowest detection limit of urinary fluoride was 0.06 mg/L (in 3 ml urine) . The recoveries of the method were 96.9%-99.5%, the inter batch precision range was 0.40%-2.89%. The intra batch precision was from 1.01 to 7.23%. Fluoride samples could be stored for 7 days at room temperature and 4 ℃, and be stored for 14 days at -20 ℃. Conclusion: Determination of fluoride in urine by ion chromatography, the method could meet the requirement in GBZ/T 210.5-2008.

Laue-DIC: a new method for improved stress field measurements at the micrometer scale.

A better understanding of the effective mechanical behavior of polycrystalline materials requires an accurate knowledge of the behavior at a scale smaller than the grain size. The X-ray Laue microdiffraction technique available at beamline BM32 at the European Synchrotron Radiation Facility is ideally suited for probing elastic strains (and associated stresses) in deformed polycrystalline materials with a spatial resolution smaller than a micrometer. However, the standard technique used to evaluate local stresses from the distortion of Laue patterns lacks accuracy for many micromechanical applications, mostly due to (i) the fitting of Laue spots by analytical functions, and (ii) the necessary comparison of the measured pattern with the theoretical one from an unstrained reference specimen. In the present paper, a new method for the analysis of Laue images is presented. A Digital Image Correlation (DIC) technique, which is essentially insensitive to the shape of Laue spots, is applied to measure the relative distortion of Laue patterns acquired at two different positions on the specimen. The new method is tested on an in situ deformed Si single-crystal, for which the prescribed stress distribution has been calculated by finite-element analysis. It is shown that the new Laue-DIC method allows determination of local stresses with a strain resolution of the order of 10(-5).

A new and simple method for concentration of enteric viruses from water.

A new type of electropositive filter media particle was tested to adsorb bacteriophage f2 and enteric viruses from tap water. 3 x nutrient broth (pH 7.2) was used to elute the adsorbed viruses, and the eluate was reconcentrated by polyethylene glycol (Mw 6000) precipitation with a final concentration of 10% (wt./vol.). The adsorption of bacteriophage was reliable and efficient, and not affected by the pH value, temperature, turbidity and organic materials in water. This method gave a recovery of Polio 1 virus 96.0% for small-volume tap water; 88.7% for large-volume water; and gave a comparable recovery of HAV, Coxsackie B3 and Echo 7 from tap water. The concentration method need not acidify virus-containing water, add exogenous multivalent cation salts, or require expensive equipment.

Suppression of radioactive strontium absorption by sodium alginate in animals and human subjects.

The effect of 23 sodium alginate preparations from different species of algae (Sargassum sp.) and kelp (Laminaria sp.) on reducing the absorption of strontium was studied in detail. A pilot production procedure has been established. Na alginate from S. siliquastrum was proven to be a potent agent for reducing Sr absorption, with high efficiency and virtually no toxicity. It reduced the body burden of strontium 3.3-4.2 fold in rats. Strontium absorption in human subjects was reduced by 78% (+/- 8.9) or completely suppressed the increase of serum Sr at 2 h after ingestion of stable Sr in volunteers and decrease 24 h urine Sr to similar extent. No undesirable effects on gastrointestinal function was observed nor were Ca, Fe, Cu and Zn metabolism changed, both in the animal experiments and in human. It was concluded that alginate preparations derived from Sargassum species are a suitable antidote against radiostrontium absorption on a long-term basis, when added to bread at a 6% level. In cases of emergency, an alginate syrup preparation appears to be more suitable because of its rapid action.

Coumarin 120 laser pulses close to the Fourier transform limit from a simplified resonant cavity.

Using a simplified resonant cavity consisted of an optical parallel glass plate and a diffraction grating at near grazing incidence and the appropriate laser parameters, coumarin 120 laser pulses close to the Fourier transform limit have been obtained. These laser pulses have a spectral linewidth of 600 +/- 40 MHz and a pulse width of 1.5 +/- 0.2 ns. The laser wavelength tuning range is from 4280 to 4600 A.

Pathways of energy flow through the light-harvesting antenna of the photosynthetic purple bacterium rhodobacter sphaeroides.

Using low intensity picosecond absorption spectroscopy with independently tunable excitation and probing infrared pulses, we have studied the pathways of energy transport through the light-harvesting antenna pigments of the photosynthetic purple bacterium Rhodobacter sphaeroides. From the observed excited-state rise time of the red-most pigment B896 as a function of excitation wavelength it is concluded that the B850 pigment of LH2 is spectrally heterogeneous. For excitations originating in the B850 pigment this results in a fast channel (9 ps) that is mainly excited in the peak of the B850 absorption band, and a slow channel (35 ps) that is predominantly excited at approximately 840 nm. Upon excitation of B800, more than 90% of the excitations follow the fast path. From the observed kinetics it is concluded that the majority of the LH2 --> LH1 energy transfer takes place within at most a few picoseconds. The rate-limiting step in the whole energy transfer sequence appears to be the B896 --> reaction center transfer. The origin of the B850 heterogeneity and the slow 35-ps component is at the moment unclear. Possibly it represents a highly extended form of LH2 in which transfer to LH1 takes a relatively long time, due to a large number of transfer steps.

Dynamics of energy transfer and trapping in the light-harvesting antenna of Rhodopseudomonas viridis.

By low intensity picosecond absorption spectroscopy it is shown that the exciton lifetime in the light-harvesting antenna of Rhodopseudomonas (Rps.) viridis membranes with photochemically active reaction centers at room temperature is 60 +/- 10 ps. This lifetime reflects the overall trapping rate of the excitation energy by the reaction center. With photochemically inactive reaction centers, in the presence of P+, the exciton lifetime increases to 150 +/- 15 ps. Prereducing the secondary electron acceptor QA does not prevent primary charge separation, but slows it down from 60 to 90 +/- 10 ps. Picosecond kinetics measured at 77 K with inactive reaction centers indicates that the light-harvesting antenna is spectrally homogeneous. Picosecond absorption anisotropy measurements show that energy transfer between identical Bchlb molecules occurs on the subpicosecond time scale. Using these experimental results as input to a random-walk model, results in strict requirements for the antenna-RC coupling. The model analysis prescribes fast trapping (approximately 1 ps) and an approximately 0.5 escape probability from the reaction center, which requires a more tightly coupled RC and antenna, as compared with the Bchla-containing bacteria Rhodospirillum (R.) rubrum and Rhodobacter (Rb.) sphaeroides.