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Various environmental poisons have caused damage to human production and life, and dioxin has seriously harmed human health. The C12H4Cl4O2(2, 3, 7, 8-tetrachlorodibenzo-p-dioxin, TCDD) is currently the most toxic compound. In order to study the influence of external electrical field on molecular structure and spectrum, herein the density functional theory (DFT) at a B3LYP/6-31+g (d,p) level is employed to calculate the geometrical parameters of the ground state of TCDD molecule under external electric fields ranging from 0 to 0.025 a.u. (0-1.2856×1010 V/m). Based on the optimized structure, time-dependent DFT at the same level as the above is adopted to calculate the absorption wavelengths and the molar absorption coefficients for the first twenty-six excited states of TCDD molecule under external electric fields. The results show that the most absorption band located at 221 nm with a molar absorption coefficient of 54064 L·mol-1·cm-1 in the UV-Vis absorption spectrum appears in the E belt, which originates from the benzene electronic transition from π to π*. In addition, a shoulder peak at 296 nm appears in the B belt, which is the characteristic absorption of aromatic compounds' electron transition from π to π*. Compared with the data in the literature, the wavelength of the shoulder is blue-shifted only 9 nm. The molecular geometry parameters are strongly dependent on the external field intensity, and the total energy decreases with external field intensity increasing. With the enhancement of external electric field, the electrons in the molecule have an overall transfer, which makes the big bond of benzene ring weakened, the energy of the transition decreases, and the wavelength of the transition increases, that is, the absorption peak is red-shifted. When the external electric field increases to 0.02 a.u., the electron cloud migration phenomenon of occupied and transition orbits of TCDD molecule are obvious, and the absorption peak red shift phenomenon is also very significant. With the enhancement of external electric field, the overall transfer of electrons in the molecule also reduces the density of the benzene rings and the surrounding electron cloud, reduces the number of electrons in the transition from π to π*, and also reduces the molar absorption coefficient. When the external electric field is enhanced to 0.02 a.u., the molar absorption coefficient decreases significantly. This work provides a theoretical basis for studying the TCDD detection and degradation method, and also has implications for other environmental pollutants detection methods and degradation mechanisms.

The engine speed characteristic simulation operation interface based on GT-POWER was developed by using VB6.0. VB has the characteristics of simple operation, high efficiency and powerful function. It can realize the background data modification, operation control and calculation result reading and storage of GT-Power model, and draw the engine speed characteristics after finishing the data. curve. Based on ACCESS database, the automatic input and storage of interface input data is realized. The data access, operation control and result reading of GT-POWER model are realized based on VB6.0 programming. The engine is validated by VB6.0 "PictureBox" control. Power, effective torque and effective ratio fuel consumption curve. For the needs of engine speed characteristic simulation, VB6.0 software is used for secondary development of GT-Power, and Chinese operation interface is obtained to simplify the operation process of engine speed characteristic simulation, reduce operation difficulty and improve calculation efficiency, which has certain engineering significance. The simulation method has the advantages of high flexibility, low cost, strong repeatability, and the like, and can obtain parameters that are inconvenient to measure. The results show that the developed engine speed characteristic simulation operation interface can simplify the operation process of engine speed characteristic simulation, reduce the operation difficulty and improve the calculation efficiency.

The author determined the occurrence of indole-3-acetic acid in sixteen Chinese marine algae collected from the east coast of China with fluorescence spectrophotometry (FS) and wheat coleoptile bioanalysis methods (WCB). The concentration of indole-3-acetic acid (IAA) presented was from 1.1–46.9 ng/g Fw (fresh weight) with FS and 5.3–110.2 ng/g Fw with WCB. The results by the two methods were in the orders of 10−3–103 ng/g Fw reported previously from multiple references.

Four bromophenols were isolated from the extract of marine red alga,Rhodomela confervoides by column chromatography and HPLC methods. By means of spectroscopic methods inclding IR, MS, 1D, and 2D-NMR techniques, their structures were elucidated as (1) 3-bromo-4,5-dihydroxy benzoic acid methyl ester; (2) bis (2,3-dibromo-4,5-dihydroxybenzyl) ether; (3) 3,4-dibromo-5-(methoxymethyl)-1,2-benzenediol and (4) 3-bromo-4,5-dihydroxy-benzaldehyde. Compound 1 was first isolated from the algae in nature, and 1, 4 were found to have selective cytotoxic activities against KB, Bel 7402 and A549 cells, 2 showed powerful antibacterial activities againstStaphylococcus aurens andPseudomonas aeruginosa.

The interface energy for a nematic liquid crystal (NLC) is considered as the sum of potential energy between LC molecules and molecules of the substrate surface, and a formula for anchoring energy is derived by elementary principles. The anchoring energy for a NLC should have two terms, the first term is the same as the Rapini–Papoular expression, the second is related to the normal of interface and resultes from the biaxial property of a NLC induced by interface. Hence there are two anchoring coefficients, W 1 and W 2. We demonstrate that W 1 is equal to the tilt angle strength Aθ , and W 2 corresponds to the difference between Aθ and the azimuthal strength Aϕ . Thus Aθ –Aϕ is due to the biaxial property of the NLC near the interface. Applying this formula to the twisted NLC cell, we discuss the threshold and saturation field, as well as the maximal tilt angel θ m with respect to Aθ /Aϕ . Previously proposed formulae are discussed from our point view.

Measurements of three chlorofluorocarbons (CFCs): trichlorofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12) and trichlorotrifluoroethane (CFC-113), along with methyl chloroform (CH3CCl3) and carbon tetrachloride (CCl4) were made in water samples from Lake Washington, using Electron Capture-Gas Chromatography (EC-GC). The samples were collected in mid-autumn, a period when the lake's upper layer undergoes rapid cooling. At the time of sampling, a strong vertical temperature gradient was present in the lake, with surface temperatures of ∼14°C, and near bottom (50 meters) temperatures of ∼8°C. The concentrations of dissolved CFC-12 and CFC-11 increased with depth, as expected from the higher solubilities of these gases at lower temperatures. Atmospheric measurements made at the sampling site at the time of the cruise, showed that CFC-11 and CFC-12 saturations in the near surface samples were 100 % and 106 %, respectively. For the deepest sample (52 meters) CFC-11 and CFC-12 saturations were 102 % and 126 %. Because the surface layer of the lake responds to changes in atmospheric CFCs on a time scale of several weeks, the higher than equilibrium concentrations of CFC-12 observed at the time of sampling may reflect earlier episodes of elevated levels of atmospheric CFC-12 in this urban area. High concentrations of dissolved CFCs in runoff or industrial effluent might also lead to elevated CFC levels in the lake. The cold, deep water of Lake Washington is relatively isolated from the effects of surface gas exchange except during winter, and the supersaturations observed in the deep layer may reflect periods of elevated atmospheric CFC-12 levels from the previous winter season. These results were compared to summertime profiles of CFC-11 and CFC-12 made in 1994.

Cation-exchange chromatography was selected to extract and separate betaines from marine algae. On the basis of the special chemical characteristics of the betaines and their analogues, Dragendorff's reagent (KBiI4) was used to test the existence of betaines and their analogues in marine algae. The total content of betaines from seven species was obtained by using the Reinkeate salt precipitation method. The results showed that the content of betaines in two species of Chlorophyta and two species of Rhodophyta were relatively high, and that the content of betaines inEnteromopha prolifera could even reach to 0.9%. The content in the three species of Phaeophyta was relatively low.

Due to its working mechanism, characteristics of the Fiber Optic Gyro (FOG) appear to be severely affected by ambient magnetic fields. Bias sensitivity to magnetic fields is an important parameter of FOG. Internal and external magnetic fields of inertial navigation system (INS) based on FOG both can cause gyro drift error. This will bring precision degradation during alignment of INS. To eliminate alignment error caused by magnetic fields and improve the performance of INS, based on magnetic fields distribution analysis of the system, a novel multi-position alignment process which substantially utilizing rotation ability of the INS with inertial measurement unit(IMU) indexing for error modulation is proposed. Experiments on different initial azimuth indicate that the method is effective. In addition, residual alignment error is discussed.

Results of neutron activation analysis (NAA) ofSargassum thumbergii samples collected from the Qingdao Taipingjiao coast on March 20, 1996 showed that (1)Sargassum thunbergii can to some extent accumulate potassium and calcium (the accumulation coefficient was 10); (2) it can accumulate almost all trace elements, especially iron, managanese and zinc; (3) it can accumulate strontium, aluminium thorium, and rare earth elements.

Results of a series of experiments (on the adsorption of divalent metal ions by dried alginic acid, Na and Ca alginates of different composition and block structure) conducted in this systematic study of the effects of the composition and structure of alginates on the static adsorption equilibrium of divalent metal ions indicate that the properties of alginate adsorption to divalent metal ions are highly different, depending not only on the cations used, but also on the form and structure of the alginates. There is close correlation between the adsorption properties and the structure of the alginates. The selectivity coefficient of Na alginate for Cd-Sr ion exchange tends to increase with the increase of theM/G ratio in alginate, whereas the adsorption capacity of Ca alginate for Cu2+ ion decrease with the increase of the G-block or the average length of the G-block $$(\bar N_G )$$ and the total adsorption capacity of alginic acid is found to vary in the same order as theF MM(diad frequency) in alginate in the mixed solution of Sr2+, Ba2+ and Cd2+.

The damage patterns created by the interactions of intense pulsed electron beams with polymeric targets reveals the processes of plasma channel formation and deposition of the beam energy and charge. There is a close structural similarity of the damage pattern with the dielectric breakdown which naturally leads to fractal structure with an exponent D ≈1.7.

When intense pulsed electron beam bombards a cold graphite target, energy and momentum transfer from electrons to graphite cause the latter to be heated and a shock pressure to be set up within the target. The direct conversion of graphite to diamond particle has been accomplished by using this method. The studies of scanning electron microscopy and Raman spectroscopy prove such a transformation.