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A portable electrode with usability, availability, and high-sensitivity is of great significance for effective on-site detection in practical situations. In this paper, a novel flexible, disposable sensor for Cd 2+ and Pb 2+ with ultrahigh sensitivity and a fast response, based on acid-etched Fe/Fe 2 O 3 encapsulated into a disposable carbon cloth electrode, has been successfully fabricated. Differential pulse anode stripping voltammetry (DPASV) was used to investigate the stripping behavior of Cd 2+ and Pb 2+ , achieving high sensitivity for Cd 2+ and Pb 2+ (338.7 and 408.0 μA mM ?1 cm ?2 ) with limits of detection (LODs) of 0.42 ppb and 0.50 ppb, respectively. Meanwhile, remarkable stability and reproducibility were obtained. Such an electrode can detect Cd 2+ and Pb 2+ in actual water samples so this is a good candidate to act as a simple and convenient sensor for general applications. More importantly, the novel disposable electrode exhibited the unique advantages of convenience, portability, and reliability compared to a conventional electrode, which may make it an alternative advantageous choice for practical on-site detection.

A novel electrochemical cytosensor was developed for the fast and high-sensitivity recognition of drug-resistant leukemia K562/ADM cells based on the P-glycoprotein (P-gp) expression level on a cell membrane. The nanocomposite interface of the gold nanoparticles/polyaniline nanofibers (AuNPs/PANI-NF) was chosen to design the biosensor for electrochemical detection. Au/PANI-NF-based cytosensors coated with anti-P-glycoprotein (anti-P-gp) molecules could provide a biomimetic interface for the immunosensing of cell surface P-glycoprotein, and thus could capture the over-expression P-gp cells. Transmission electron microscopy (TEM) indicated that the gold nanoparticles were uniformly anchored along the structure of the PANI-NF surface, displaying fibrillar morphology with a diameter of ～70 nm, and atomic force microscopy (AFM) further presented the morphology of the nanocomposite film. Owing to the high affinity of anti-P-gp for leukemia K562/ADM cells of the propounded sensing platform, the proposed biosensor exhibited excellent analytical performance for leukemia K562/ADM cells, ranging from 1.6 × 10 2 to 1.6 × 10 6 cells per mL with a detection limit of 80 cells per mL. Recovery experiments indicated that the sensitivity reported here is suitable for practical application. The cell surface P-gp expression level was analysed by flow cytometric experiments, which confirmed the above recognized result. This strategy is also a cost-effective and convenient operation, implying great promise for the sensitive recognition of cancer cells and cell surface receptors; thus, it is helpful in cancer diagnosis.

A kinetic study of the oxidation of Bordeaux by potassium bromate is reported and a rate equation and reaction sequence are proposed. The reaction was found to be autocatalytic and the rate of the reaction at any time to depend on the concentration of Bordeaux reacted at that time. Equations are derived that describe the reaction of Bordeaux under the conditions used and the time required for the oxidation of Bordeaux to reach completion. The reaction is susceptible to trace impurities of bromide present in the samples of potassium bromate used, and it was found necessary to allow for these in the derivation of the rate equation. Three rate-controlling reactions are described and rate constants and activation energies for all three reactions are given.

A lateral flow strip biosensor for fast, sensitive, low-cost and on-site detection of kanamycin was developed by using kanamycin-specific aptamer-modified gold nanoparticles (AuNPs-apt) as a probe and oligonucleotide DNA1-modified silver nanoparticles (AgNPs-DNA1) as a signal amplification element. Through the complementary sequences of DNA1 and the aptamer, the AgNP-DNA1-apt-AuNPs complex can be formed and further captured on the test zone of the strip, where a capture probe DNA2 complementary to the 3′-terminal of DNA1 was immobilized. In the presence of kanamycin, it can competitively bind to the aptamer, and then inhibit the formation of the complex and the accumulation of AuNPs on the test zone. AuNPs-apt can finally be captured on the control zone via the specific binding between biotin and streptavidin. The assay avoids multiple incubation and washing steps and can be completed within 10 min. By observing the color change of the test zone, a qualitative detection for kanamycin can be achieved by the naked eye, with the visual limit of 35 nM. Meanwhile, a linear detection range of 1–30 nM with a low detection limit of 0.0778 nM for quantitative analysis can be achieved by using a scanning reader. The lateral flow strip biosensor exhibited high specificity and stability. Moreover, it was applied to detect kanamycin in various food samples, indicating its great potential in field testing.

Electrochemical aptasensors can detect disease markers such as cytokines to provide point-of-care diagnosis that is low-cost, rapid, specific and sensitive. Herein, we describe the development of an aptamer-based electrochemical sensor for detection and analysis of tumor necrosis factor-alpha (TNF-α) – a key inflammatory cytokine – in whole human blood. When testing spiked blood, a TNF-α detection limit of 58 pM (10 ng mL ?1 ) and a linear range of 6 nM (100 ng mL ?1 ) could be achieved. Furthermore, detection of TNF-α in mitogen stimulated whole blood was demonstrated.

For the first time, we report the acoustic wave detection of chemical species being transported in a capillary tube to a region where acoustic coupling occurs. The measured parameter was a change in phase, which was originally only attributed to a change in solution density as the analyte passed by the detection region. Accordingly, we report the detection of change in phase as various chemical species ( e.g. Cy5 dye, Cy5-derivatized glycine and underivatized glycine ) were introduced into and migrated along a capillary tube through electrokinetic processes. To improve detection sensitivity, we modified various experimental parameters, such as run buffer concentration, capillary wall thickness and transducer frequency. Although acoustic wave detection was feasible, the peak width and detection limit were inadequate as compared to conventional detection methods for HPLC or CE. Nevertheless, the effects of various physical and chemical relaxation processes on acoustic wave absorption were discussed, and this has shed some light on explaining some observations, which cannot be explained by density differences alone. Accordingly, the acoustic wave method is suggested to investigate these processes, as studied in ultrasonic relaxation spectroscopy , in a flow system.

An automated method for the determination of boron in sewage, sewage effluents and river waters on the Technicon AutoAnalyzer is described. The reaction of carminic acid with boron in concentrated sulphuric acid is used. The limit of detection is about 0·02 mg l –1 of boron and the standard deviation is ±0·03 mg l –1 at concentrations of 3·0 mg l –1 of boron. The interference of nitrate and its suppression by the use of phenol are examined.

An automated method for the determination of lead in calcium carbonate, lime and limestone with the Technicon AutoAnalyzer is described. The method is based on the extraction of lead from an acidic chloride solution of the sample with a long-chain amine liquid ion exchanger, followed by re-extraction into an ammonia-ammonium citrate buffer at pH 9. Finally, the lead is extracted as the lead-dithizone complex into chloroform and the optical density of the complex measured at 510 nm. The separation of lead prior to formation of the lead-dithizone complex results in low background and blank readings. Lead levels of 0 to 20 p.p.m. can be determined at a rate of twenty samples per hour. Other trace metals which occur in calcareous materials do not interfere.

A spectrophotometric method for the determination of molybdenum in steel, based on the colour reaction with thiocyanate in the presence of tin(II) chloride and a titanium catalyst, has been adapted for the Technicon AutoAnalyzer. The method is suitable for most steels, but small corrections may be needed in the presence of high concentrations of chromium, cobalt and vanadium. Nickel, manganese and silicon at the usual levels do not interfere. For low-alloy steels the initial solution is identical with that required for an existing automatic method for manganese and phosphorus, but is modified when required to deal with high-speed steels containing alloying additions of tungsten. Results on standard steels are presented, and a statistical survey of long-term reproducibility is given.

An apparatus is described which combined the electronic measurement of the flow time of a liquid through a capillary viscometer with a programmed sequence for taking a pre-determined number of successive measurements on a single sample. Typical results are tabulated to show that the measurements are capable of a high degree of precision. The equipment has been designed with flexibility to allow for development to perform automatically other operations in capillary viscometry.