Kinetic Spectrophotometric Determination of Trace Iron (III) with p-Amino-N,N-Dimethylaniline Dihydrochloride and Hydrogen Peroxide

A new, simple and highly sensitive kinetic method for the determination oftrace iron (III) has been developed based on the catalytic effect of iron (III) on colorreaction of p-amino-N, N-dimethylaniline dihydrochloride (p-DMA) oxidated by hydrogenperoxide. The reaction is followed spectrophotometrically by measuring the absorbanceat 510 nm. The detection limit is 4.47×10-11 g/ml, and the calibration curve is linear inthe range of 0-0.10μg Fe(III) /25 ml with a relative standard deviation of ±3.25%. Themethod has been applied to the determination of iron in tap-water, chemical reagents andhuman hair.

Profile of Absolute Light Utilization Efficiency Within Leaves of Euonymus japonicus

Absolute light utilization efficiency across leaf section of Euonymus japonicus T. was calculated based on the measurements of photoacoustic technique (PA technique) and microscopic fiber optic probe. This new method was based on the principal of depth analysis by PA technique and the differential analysis of light gradients across leaf section by micro-optical probe technique. The depth analysis was shown by a sample of PA scan light absorption spectra. Results showed that the tissue layers between palisade tissue and spongy tissue used the smallest proportion of incident light energy for photochemical reactions (about 0.026% incident light energy of 660 nm light), while in tissue layer more close to the adaxial surface of leaf or the abaxial surface of leaf, the efficiency of utilization of light energy tended to be improved, e. g. 0.092% for tissue layers close to adaxial surface; 0.036% for tissue layers close to abaxial surface. The results that different leaf tissue layers utilized different proportion of incident light energy for photochemical reaction directly prove the hypothesis put forward by Han and Vogelmann.

Determination of the Trace Element Contents in Plants Using Atomic Absorption Spectrophotometer

The aim of the study is to investigate the contents of trace element Se, Cd, Pb in three plants including burdock, ginkgol and garlic via graphite furnace atomic absorption and standard addition method. The results show that Se in burdock stem, skin and leaf are 32.40, 48.63, 38.10 μg/g, respectively; Cd in burdock stem, skin and leaf are 0. 160 0, 0. 300 0, 0. 140 0 μg/g, respectively; Cd in burdock stem, skin and leaf are 2. 020, 3. 960, 2. 410 μg/g, respectively. In the ginkgo and ginko leaf, Se contents are 17.63 and 16.91 μg/g, respectively ; for Cd are 0. 181 0 and 0.2020μg/g, respectively ; for Pb are 3. 572 and 4. 021 μg/g, respectively. In garlic, Se, Cd and Pb are 73. 900 0, 6. 900 0 and 0. 390 0, respectively. All the standard deviations of measured results are below 2.3%, recovery rate are from 99% to 101%.

Research on Activity and Expression of Tyrosinase in Varicorhinus macrolepis

[Objective] This study aimed to analyze tyrosinase activity and its expression in Varicorhinus macrolepis. [Method] V. macrolepis was used as experimental material for the analysis and research of tyrosinase in nine kinds of organs and tissues of male and female V. macrolepis individuals by using polyacrylamide gel electrophoresis and biochemical staining method, spectrophotometry and enzyme histochemical technology. [Result] Tyrosinase exists in the liver and pancreas, intestine and spleen of female and male V. macrolepis and in the gallbladder of male V. macrolepis. Tyrosinase activities in various tissues of V. macrolepis varied largely. Specifically, tyrosinase activities in the spleen was the maximum, which was higher in female V. macrolepis than in males. According to the enzyme histochemistry results, strong positive signals of tyrosinase existed in the spleen, intestine, liver and pancreas and gallbladder of V. macrolepis, which was the strongest in the spleen. [Conclusion] In this paper, research on tissue localization of tyrosinase in V. macrolepis had been first reported, which provided theoretical basis for further exploring the functions of tyrosinase in V. macrolepis.

Pharmacokinetics and Biodegradation of Chitosan in Rats

Chitosan, an excellent biomedical material, has received a widespread in vivo application. In contrast, its metabolism and distribution once being implanted were less documented. In this study, the pharmacokinetics and biodegradation of fluorescein isothiocyanate(FITC) labeled and muscle implantation administrated chitosan in rats were investigated with fluorescence spectrophotometry, histological assay and gel chromatography. After implantation, chitosan was degraded gradually during its distribution to diverse organs. Among the tested organs, liver and kidney were found to be the first two highest in chitosan content, which was followed by heart, brain and spleen. Urinary excretion was believed to be the major pathway of chitosan elimination, yet 80% of chitosan administered to rats was not trackable in their urine. This indicated that the majority of chitosan was degraded in tissues. In average, the molecular weight of the degradation products of chitosan in diverse organs and urine was found to be <65 k Da. This further confirmed the in vivo degradation of chitosan. Our findings provided new evidences for the intensive and safe application of chitosan as a biomedical material.

STUDY ON THE DETERMINATION OF TRACE Fe(Ⅲ) BY THIN LAYER RESIN PHASE SPECTROPHOTOMETRY

A method to determine Fe（Ⅲ） by thin layer resin phase spectrophotometry has been developed in this paper. The colored complex formed by Fe（Ⅲ） and 1,2-benzendiol is concentrated on the 717^# resin, then Fe（Ⅲ） can be determined directly by making thin layer. The method is sensitive with a apparent molar absorption of 4.8×10^4L/mol.cm, which is 16 times higher than that of liquid phase spectrophotornetry, most coexisting ions do not influence the determination. The detection limit for Fe（Ⅲ） is 1.47μg/L with the precision of 3.3% [n=6, 7μg/50mL Fe（Ⅲ）]. The calibration curve is linear in the range of 0-25μg/50mL. The preposed method was applied to the determination of Fe（Ⅲ） in water sample with satisfactory results.

Photocatalytic activity of bauxite-tailings supported nano-TiO_2

TiO2/bauxite-tailings （TiO2/BTs） composites were prepared via a chemical liquid deposition method and characterized by X-ray diffractometry （XRD）, scanning electronic microscopy （SEM） and N2 adsorption analysis. The photocatalytic performance of TiO2/BTs composites was evaluated with UV-Vis spectrophotometer following the changes of phenol concentration under different illumination time. Effects of the calcination temperature, the pH and the cycles on the photocatalytic activity of TiO2/BTs composites were investigated. The composites calcined at 500 and 600 ℃ exhibit the best photocatalytic performance, and the phenol degradation ratios reacting for 40 and 160 rain reach 35% and 78% respectively under the same conditions, higher than those of 29% and 76% of the Degussa P25（TiO2）. The ability of TiO2/BTs500 （BTs500 represents bauxite-tailings calcined at 500 ℃） composites to degrade phenol increases with decreasing pH.

Protective effect of tea polyphenols against paracetamol-induced hepatotoxicity in mice is significanly correlated with cytochrome P450 suppression

AIM： To investigate the hepatoprotective activity of tea polyphenols （TP） and its relation with cytochrome P450 （CYP450） expression in mice. METHODS： Hepatic CYP450 and CYPbs levels were measured by UV-spectrophotometry in mice 2 d after intraperitoneal TP （25, 50 and 100 mg/kg per day）. Then the mice were intragastricly pre-treated with TP （100, 200 and 400 mg/kg per day） for six days before paracetamol （1000 mg/kg） was given. Their acute mortality was compared with that of control mice. The mice were pre-treated with TP （100, 200, and 400 mg/kg per day） for five days before paracetamol （500 mg/kg） was given. Hepatic CYP2E1 and CYPIA2 protein and mRNA expression levels were evaluated by Western blotting, immunohistochemical staining and transcriptase-polymerase chain reaction. RESULTS： The hepatic CYP450 and CYPb5 levels in mice of TP-treated groups （100, 200 and 400 mg/kg per day） were decreased in a dose-dependent manner compared with those in the negative control mice.TP significantly attenuated the paracetamol-induced hepatic injury and dramatically reduced the mortality of paracetamol-treated mice. Furthermore, TP reduced CYP2E1 and CYPIA2 expression at both protein and mRNA levels in a dose-dependent manner. CONCLUSION： TP possess potential hepatoprotective properties and can suppress CYP450 expression.

LO-RAY-LIGH@ Diffraction Gratings in UV-VIS Spectroscopy

It has been more than half a century since the release of the first Shimadzu UV-VIS （UV-visible） spectrophotometer QB-50 in 1952, and during this time more than 160,000 UV-VIS spectrometers have been produced and installed in a wide variety of different applications. A lot of technical innovations have been implemented to improve the performance and significantly reduce the stray light levels. The latest innovation during development of sophisticated spectrophotometers is based on a new holographic exposure method and optimized etching process which has made it possible to produce both high-efficient and exceptionally low stray light gratings. These LO-RAY-LIGH~ gratings have guaranteed values of stray light at the intermediate position between zero-order and first-order lights. The values are measured by Shimadzu＇s laser stray-light-measuring system. The latest development in the series of UV-VIS spectrophotometers is the UV-2700 which is a true double beam double monochromator system in a compact design for high-precision spectral analysis of a wide range of samples including organic and inorganic compounds, biological samples, optical materials and photovoltaics. The high performance optical system is designed with ＂LO-RAY-LIGH＂ diffraction gratings, featuring highest efficiency and exceptionally low stray light. The spectrophotometer operates in the wavelength range from 185 nm to 900 nm and allows highly sophisticated applications such as direct measurement of high density samples up to 8 absorbance units without dilution.

Efficacy of Photogem（Hematoporphyrin Derivative） as a Photoactivatable Larvicide against Aedes aegypti （Diptera： Culicidae） Larvae

Dengue vector is responsible for millions of deaths every year and has caused disastrous impacts on health systems. The continuous use of chemical insecticides, such as carbamates, pyrethroids and organophosphates generates resistant populations of the mosquito, therefore, new control methods must be investigated. The joint action of the population and guidelines for preventing the reproduction of the mosquito associated with the use of photoactivatable insecticides can be the alternative for the control of epidemiological outbreaks in affected regions. In this study, the photo-larvicidal activity of Photogem^（PG）, a derivative of hematoporphyrin, was investigated against 2nd-early 3rd instar of Aedes aegypti larvae （Diptera： Culicidae） under different lighting conditions （artificial lighting system and sunlight）. The dynamics of PG accumulation was characterized by CLSM （confocal laser scanning microscopy） and total time PG eliminationin solution was investigated by ultraviolet-visible spectrophotometry. The maximum photo-activity of PG was observed in 0.5 h under sunlight exposure which achieved 100% larval mortality. Fluorescence images showed a uniform distribution of PG along the digestive tract. PG remained stable in the sunlight for 48 h and in an artificial lighting system for longer periods, therefore, it can be used for the control ofAedes aegypti larvae as a new alternative to chemical insecticides. The method is considered environmentally friendly due to its rapid degradation in the presence of light. Further studies are required, so that the potential of the technique can be explored in real breeding places.

Variation of temporal and spatial patterns of NO_2 in Beijing using OMI and mobile DOAS

Control policies such as "odd-and-even license plate rule" were implemented by the Chinese government to restrict traffic and suspend factory production in Beijing and neighboring cities during the Asia-Pacific Economic Cooperation summit. We use ozone monitoring instrument(OMI), mobile differential optical absorption spectroscopy(DOAS), and multi-axis differential optical absorption spectroscopy(MAX-DOAS) to measure the variation of the spatial and temporal patterns of NO2 column densities from October 24, 2014 to November 22, 2014. It is found that the NO2 column densities during the episode of control policies are significantly lower than those during other periods, and the emission flux of NO2 calculated by mobile DOAS is also lower than the results from other periods. Some daily low NO2 column densities occur with the northwest wind direction. We then compare the relationship between OMI and mobile DOAS NO2 column density observations, and the results of mobile DOAS are approximately 2.7 times larger than the OMI values. The largest discrepancy occurs in the northern part of Beijing city. In other parts, the two instruments have a better correlation coefficient(R2) of 0.61. The low NO2 column densities that occur during the episode of control policies are affected by the control policies as well as meteorological conditions.

Time distribution characteristics of cat-eye reflected light from moving optical target

By using the Collins diffraction formula and expanding the aperture function into a fmite sum of complex Gaussian functions, an analytical formula of the time light intensity distribution for oblique Gaussian beams passing through a moving cat-eye optical lens and going back along the entrance way is deduced. By numerical computation, the variation laws of the time intensity distributions of the cat-eye reflected light with the viewing angle, imaging distance, aperture and instantaneous field of view are given. The results show that the relationship between the light intensity at the return place and the detection time is linear, and it is of inverse proportion only when the viewing angle is very large. For the staring imaging optical lens, the nonlinear extent of the time distribution curve becomes larger with the decrease of the viewing angle. For the instantaneous imaging optical lens, there is still some cat-eye reflected light when the detection system is out of the viewing field of the target lens.

Velocity and Size of Droplets in Dense Region of Diesel Fuel Spray on Transient Needle Opening Condition

In order to investigate the effect of transient needle opening on early stage of spray behavior, simultaneous measurements of velocity and size of droplet were conducted by a newly developed laser 2-focus velocimeter (L2F). The micro-scale probe of the L2F was consisted of two foci with a distance of 36μm. The tested nozzle had a single hole with a diameter of 0.2 mm. The measurements of injection pressure, needle lift, and crank angle were synchronized with the spray measurement by the L2F at the position 10 mm downstream from the nozzle exit. It has been clearly shown that the velocity and size of droplet increase with needle valve opening and that the probability density distribution of droplet size can be fitted to the Nukiyama-Tanasawa distribution under the transient needle opening condition.

Comparison of SO_2 column retrievals from BRD and DOAS algorithms

Atmospheric SO_2 has a significant impact on the urban environment and global climate. Band Residual Difference Algorithm(BRD) and Differential Optical Absorption Spectroscopy(DOAS) were used respectively by NASA and ESA science team to derive SO_2 columns from satellite observations, but there are few studies on the comparison and validation of BRD and DOAS SO_2 retrievals under the same observation conditions. In this study, the radiative transfer model SCIATRAN was firstly used to validate the accuracies of BRD and DOAS SO_2 retrievals, and analyse the uncertainty of SO_2 retrieval caused by band selection,O_3 absorption, aerosol, surface reflectance, solar and viewing zenith angle. Finally, BRD and DOAS algorithms were applied to the same radiances from satellite observations, and comparisons of BRD and DOAS SO_2 retrievals were conducted over volcanic eruption and North China. Results show that, for the case with low SO_2 columns, BRD SO_2 retrievals have higher retrieval accuracy than DOAS, but typical seasonal variation with high SO_2 column in winter and low in summer can be more clearly discernible in DOAS SO_2 retrievals than BRD from satellite observations. For the case with high SO_2 columns, the differences between BRD(310.8–314.4 nm) and DOAS(315–327 nm) retrievals are large, and the value and accuracy of BRD(310.8–314.4 nm) SO_2 retrievals are lower than those of DOAS(315–327 nm) retrievals. Compared with the SO_2 inputs in forward model, both BRD(310.8–314.4 nm) and DOAS(315–327 nm) SO_2 retrievals are underestimated for the case with high SO_2 columns. The selection of wavelength range can significantly affect the accuracy of SO_2 retrieval. The error of BRD SO_2 retrieval from 310.8–314.4 nm is lower than other bands in the ultraviolet spectral region(306–327 nm). The increase of wavelength in the ultraviolet spectral region306–330 nm can reduce the underestimation of DOAS SO_2 retrievals in the case of high SO_2 column, but slight overestimation of SO_2 retrieval is found from the 315–327 nm range in the case of low SO_2 column. The values of BRD and DOAS SO_2 retrieval decrease with atmospheric O_3 column and aerosol optical depth increasing, but increase with surface reflectance increasing. Large solar zenith angle and viewing zenith angle can introduce more errors to the BRD and DOAS SO_2 retrievals. This study is important for the improvement of retrieval algorithm and the application of SO_2 products from satellite observations.