Advances in Research of Collection and Detection Methods of Microplastics in Environment

As a new type of environmental pollutants,microplastics have gradually attracted people's attention.A large number of plastics discharged into the environment by human beings are constantly aging and breaking,and finally become microplastics.Microplastics can adsorb pollutants in the environment,and their components have certain toxicity,which can cause different degrees of harm to organisms.Due to the structural characteristics of microplastic particles,such as small particle size,large specific surface area,and their distribution in different environmental media,it is very difficult to accurately detect microplastics.Reliable collection and detection methods are the key to the study of environmental behavior of microplastics.In this study,the collection and detection methods of microplastics in the environment were reviewed,and the development direction of microplastics detection technology in the future was prospected.This study has a certain reference value for the related research and the prevention and treatment of micro-plastic pollution.

Semi-analytical method of calculating the electrostatic interaction of colloidal solutions

We present a semi-analytical method of calculating the electrostatic interaction of colloid solutions for confined and unconfined systems. We expand the electrostatic potential of the system in terms of some basis functions such as spherical harmonic function and cylinder function. The expansion coefficients can be obtained by solving the equations of the boundary conditions, combining an analytical translation transform of the coordinates and a numerical multipoint collection method. The precise electrostatic potential and the interaction energy are then obtained automatically. The method is available not only for the uniformly charged colloids but also for nonuniformly charged ones. We have successfully applied it to unconfined diluted colloid system and some confined systems such as the long cylinder wall confinement, the air–water interfacial confinement and porous membrane confinement. The consistence checks of our calculations with some known analytical cases have been made for all our applications. In theory, the method is applicable to any dilute colloid solutions with an arbitrary distribution of the surface charge on the colloidal particle under a regular solid confinement, such as spherical cavity confinement and lamellar confinement.

Oral supplementation of selenium improves post-thaw sperm quality in Saanen bucks

Objective:To determine the effect of oral selenium supplementation and semen collection methods on various post thaw semen quality parameters in Saanen bucks.Methods:Sixteen healthy bucks were divided into two equal groups(n=8 each).The treatment group received selenium at 10-day intervals for three months.Sperm kinematic parameters,morphological parameters,mitochondrial membrane potential,plasma membrane functionality,and sperm DNA integrity were evaluated weekly pre and post-cryopreservation.Results:The mean percentages of the morphological abnormalities were significantly lower in the selenium-supplemented samples when semen was collected by using artificial vagina method(P<0.05).Proximal droplet defects were significantly lower in the selenium supplementation group when semen was collected by electro-ejaculation(P<0.05).Post-thaw sperm parameters such as total motility and progressive motility were significantly higher when semen was obtained by artificial vagina in the selenium-supplemented bucks compared to the electro-ejaculation and the control groups(P<0.05).The sperm kinematic parameters such as curvilinear velocity,average path velocity,and amplitude of lateral head displacement were significantly higher when semen was collected by artificial vagina in the selenium-treated bucks(P<0.05).The percentages of sperm with intact and functional plasma membrane and functional mitochondria were significantly higher in the selenium-supplemented samples collected with artificial vagina compared to the electro-ejaculation method and the control groups(P<0.05).In vitro fertilizing potential was significantly higher in the selenium-supplemented samples collected with artificial vagina compared to the electro-ejaculation method and the control groups,respectively(P<0.05).Conclusions:Oral supplementation of selenium and artificial vagina semen collection improve post thaw sperm quality parameters of Saanen buck.

Applying a new method for direct collection, volume quantification and determination of N_2 emission from water

The emission of N2 is important to remove excess N from lakes, ponds, and wetlands. To investigate the gas emission from water, Gao et al.（2013） developed a new method using a bubble trap device to collect gas samples from waters. However, the determination accuracy of sampling volume and gas component concentration was still debatable. In this study, the method was optimized for in situ sampling, accurate volume measurement and direct injection to a gas chromatograph for the analysis of N2 and other gases. By the optimized new method, the recovery rate for N2 was 100.28% on average; the mean coefficient of determination（R2） was 0.9997; the limit of detection was 0.02%. We further assessed the effects of the new method, bottle full of water, vs. vacuum bag and vacuum vial methods, on variations of N2 concentration as influenced by sample storage times of 1,2, 3, 5, and 7 days at constant temperature of 15°C, using indices of averaged relative peak area（%） in comparison with the averaged relative peak area of each method at 0 day.The indices of the bottle full of water method were the lowest（99.5%–108.5%） compared to the indices of vacuum bag and vacuum vial methods（119%–217%）. Meanwhile, the gas chromatograph determination of other gas components（O2, CH4, and N2O） was also accurate. The new method was an alternative way to investigate N2 released from various kinds of aquatic ecosystems.

Fabrication of nano-sized Ca(OH)_2 with excellent adsorption ability for N_2O_4

Uniform nano-sized calcium hydroxide （Ca（OH）2） monocrystal powder was synthesized from calcium oxide in a surfactant solution via a digestion method by decreasing the surface tension of the reaction system to control the growth of crystalline Ca（OH）2. The Ca（OH）2 monocrystal powder samples were characterized by means of scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, high resolution transmission electron microscopy （HRTEM）, X-ray diffraction （XRD）, Brunauer-Emmett-Teller （BET）, and Fourier transform-infrared spectroscopy （FT-IR）. The NOx adsorption ability of the samples was evaluated, and the influence of various types and concentrations of surfactants on powder agglomeration and then the specific surface area in the precipitation process were studied. The specific surface area of the samples was found as high as 58 m2/g and 92 m2/g and the particle size, 300-400 nm and 200-300 nm in the presence of 10 wt% PEG600 and 0.086 mL/L SDS at a reaction time of 5 h, respectively. The product has an exceptionally strong adsorption ability for NOx, which makes it a highly promising adsorbent for emission control and air purification.