铜掺杂ZnSe量子点荧光探针测定镉(Ⅱ)

基于镉(Ⅱ)与ZnSe/Cu量子点之间的荧光猝灭作用,提出了用ZnSe/Cu量子点作为荧光探针测定镉的方法。通过微波辅助加热,在水溶液中合成了巯基丙酸修饰的ZnSe/Cu量子点。用荧光光谱、紫外光谱研究了ZnSe/Cu量子点与镉(Ⅱ)的相互作用。在pH为7.4的三羟甲基氨基甲烷-盐酸缓冲溶液和1.5×10-4 mol·L-1 ZnSe/Cu量子点溶液中测定镉(Ⅱ)。镉(Ⅱ)的质量浓度在0.025~0.40mg·L-1范围与ZnSe/Cu量子点荧光猝灭强度呈线性关系,方法的检出限(3s/k)为0.021 6mg·L-1。方法应用于水样的测定,回收率为98.0%,102%。对0.15mg·L-1镉(Ⅱ)标准溶液测定11次,测定值的相对标准偏差为6.7%。     

饱和土中的任意形状孔洞对弹性波的散射

根据Biot波动理论建立了求解饱和土中任意形状孔洞对弹性波散射问题的复变函数方法.首先通过引入位移势函数把稳态条件下的Biot波动方程解耦为势函数所满足的Helmholtz方程.利用分离变量方法即得到Helmholtz方程完备的通解.根据所得位移势函数的通解,可得骨架位移、流体相对骨架的位移、应力和孔压的表达式.通过保角变换方法,把物理平面上的孔洞映射到像平面上单位圆.利用土骨架和流体的边界条件,即可确定波函数展开式中的未知系数.给出了一些数值结果.     

Comparative Analysis of Microbial Consortiums and Nanoparticles for Rehabilitating Petroleum Waste Contaminated Soils

Nano-bioremediation application is an ecologically and environmentally friendly technique to overcome the catastrophic situation in soil because of petroleum waste contamination. We evaluated the efficiency of oil-degrading bacterial consortium and silver nanoparticles (AgNPs) with or without fertilizer to remediate soils collected from petroleum waste contaminated oil fields. Physicochemical characteristics of control soil and petroleum contaminated soils were assessed. Four oil-degrading strains, namely Bacillus pumilus ({"type":"entrez-nucleotide","attrs":{"text":"KY010576","term_id":"1248281175"}}KY010576), Exiguobacteriaum aurantiacum ({"type":"entrez-nucleotide","attrs":{"text":"KY010578","term_id":"1248281177"}}KY010578), Lysinibacillus fusiformis ({"type":"entrez-nucleotide","attrs":{"text":"KY010586","term_id":"1248281185"}}KY010586), and Pseudomonas putida ({"type":"entrez-nucleotide","attrs":{"text":"KX580766","term_id":"1159332275"}}KX580766), were selected based on their in vitrohydrocarbon-degrading efficiency. In a lab experiment, contaminated soils were treated alone and with combined amendments of the bacterial consortium, AgNPs, and fertilizers (ammonium nitrate and diammonium phosphate). We detected the degradation rate of total petroleum hydrocarbons (TPHs) of the soil samples with GC-FID at different intervals of the incubation period (0, 5, 20, 60, 240 days). The bacterial population (CFU/g) was also monitored during the entire period of incubation. The results showed that 70% more TPH was degraded with a consortium with their sole application in 20 days of incubation. There was a positive correlation between TPH degradation and the 100-fold increase in bacterial population in contaminated soils. This study revealed that bacterial consortiums alone showed the maximum increase in the degradation of TPHs at 20 days. The application of nanoparticles and fertilizer has non-significant effects on the consortium degradation potential. Moreover, fertilizer alone or in combination with AgNPs and consortium slows the rate of degradation of TPHs over a short period. Still, it subsequently accelerates the rate of degradation of TPHs, and a negligible amount remains at the end of the incubation period.     

Rapid Detection of Different Types of Soil Nitrogen Using Near-Infrared Hyperspectral Imaging

Rapid and accurate determination of soil nitrogen supply capacity by detecting nitrogen content plays an important role in guiding agricultural production activities. In this study, near-infrared hyperspectral imaging (NIR-HSI) combined with two spectral preprocessing algorithms, two characteristic wavelength selection algorithms and two machine learning algorithms were applied to determine the content of soil nitrogen. Two types of soils (laterite and loess, collected in 2020) and three types of nitrogen fertilizers, namely, ammonium bicarbonate (ammonium nitrogen, NH₄-N), sodium nitrate (nitrate nitrogen, NO₃-N) and urea (urea nitrogen, urea-N), were studied. The NIR characteristic peaks of three types of nitrogen were assigned and regression models were established. By comparing the model average performance indexes after 100 runs, the best model suitable for the detection of nitrogen in different types was obtained. For NH₄-N, R²_p = 0.92, RMSE_P = 0.77% and RPD = 3.63; for NO₃-N, R²_p = 0.92, RMSE_P = 0.74% and RPD = 4.17; for urea-N, R²_p = 0.96, RMSE_P = 0.57% and RPD = 5.24. It can therefore be concluded that HSI spectroscopy combined with multivariate models is suitable for the high-precision detection of various soil N in soils. This study provided a research basis for the development of precision agriculture in the future.     

An approach to analysis of single pier based on the variational principle in multi-layered soil

In this study, a variational approach to the settlement analysis of an axially loaded pier embedded in a multi-layered soil profile is presented. In this method, the soil profile and the embedded pier are divided into a number of sub-layers according to the actual number of soil layers observed in the field. The displacement shape function of each soil layer is given as a product of an exponential equation along the pier depth and the Bessel's solution in the radial direction. The displacement relationship among the layers can be derived through the transformation matrices. One of the major features of this method is that the total number of pier elements is the same as that of soil sub-layers. All the field components, such as the displacement, stress, and strain in the soil, can be calculated by closed-form solutions except that the only unknown variable is the value β which can be determined by iteration techniques. Comparisons were made with the results of finite element analysis and the field observation in pile-loaded tests.     

污染环境中的Leslie系统

研究了环境污染对Leslie资源-消费者系统中消费者种群的长期影响．考虑到种群数量的变化对种群体内毒素浓度和环境毒素浓度的影响,建立了一个新的数学模型, 给出了消费者种群弱持续生存和绝灭的判据,并在一定条件下得到了弱持续生存与绝灭的阈值．     

Characterization of burned soil profiles by Mössbauer spectroscopy

The characteristics of both natural burned and experimentally burned soil profiles as seen by Mössbauer spectroscopy are described. The results help in the identification of profiles where biological and/or chemical processes may have been involved.     

Indium tin oxide thin films by bias magnetron rf sputtering for heterojunction solar cells application

In this investigation ITO thin films were prepared by bias magnetron rf sputtering technique at substrate temperature of 180 °C and low substrate-target distance for future a-Si:H/c-Si heterojunction (HJ) solar cells application. Microstructure, surface morphology, electrical and optical properties of these films were characterized and analyzed. The effects of ion bombardments on growing ITO films are well discussed. XRD analysis revealed a change in preferential orientation of polycrystalline structure from (2 2 2) to (4 0 0) plane with the increase of negative bias voltage. Textured surface were observed on AFM graphs of samples prepared at high negative bias. Hall measurements showed that the carrier density and Hall mobility of these ITO films are sensitive to the bias voltage applied. We attributed these effects to the sensitivity of energy of Ar⁺ ions bombarding on growing films to the applied bias voltage in our experiments. At last the figure of merit was calculated to evaluate the quality of ITO thin films, the results of which show that sample prepared at bias voltage of −75 V is good to be used in HJ cells application.     

Transient analysis of piles and pile groups in non-homogeneous soil

In this paper, the transient analysis of a single pile and a 3 × 3 pile group is presented for Gibson type non-homogeneous soil by using a hybrid type of boundary and finite element formulation for the soil domain and pile domain, respectively. The formula is presented for a transient point force acting in the interior of a non-homogeneous, isotropic half space. A time stepping boundary element algorithm for soil domain is used together with an implicit time integration scheme for finite pile domain. To investigate the validity of this formulation, a single pile and a pile group are analyzed under Heaviside loading and triangular transient loading. In the analyses, it can be concluded that the results agree well for all cases of the inhomogeneity index by comparing the Laplace domain solutions.     

Gas flow sputtering: Versatile process for the growth of nanopillars, nanoparticles, and epitaxial thin films

Gas flow sputtering is a sputter-deposition method that enables soft and high-rate deposition even for oxides or nitrides. It involves sputtering at a high pressure of around 100 Pa and hollow cathode discharge in a tubular or parallel plate target with forced Ar flow. Depending on the sputtering conditions, various structures of magnetic materials are obtained, and some examples are shown in this paper. Co-Pt and Fe nanopillars are fabricated using a tubular target with a large inner diameter (6-40 mm). Fe nanoparticles with diameters ranging from a few nanometers to 150 nm are fabricated using a tubular target with a small inner diameter (5 mm). Magnetite epitaxial thin films are fabricated on MgO and GaAs substrates by substrate heating.