Divergent Reaction of Indoline-derived Azadienes with α-Bromohydroxamates: Synthesis of Spiro-indolinepyrrolidinones and Indoline-fused Diazepinones.

A divergent reaction of indoline-derived azadienes with α-bromohydroxamates for the selective synthesis of spiro-indolinepyrrolidinones and indoline-fused diazepinones was disclosed. This reaction sequence involved an initial formation of five-membered spirocyclic products followed by an intramolecular ring-opening and ring expansion to produce seven-membered diazepinones. We demonstrated that controlling the reaction time could modulate the reaction pathway for formation of different molecular frameworks for the same set of substrates. Based on the experimental results, the reaction mechanism was also discussed and proposed to explain the phenomena observed in the process.

A Plastic Optical Fiber Sensing System for Bridge Deflection Measurement.

Deflection is one of the key parameters that reflects the state of a bridge. However, deflection measurement is difficult for a bridge that is under operation. Most existing sensors and measuring techniques often do not meet the requirements for health monitoring for various types of bridges. Therefore, based on changes of optical fiber intensity, a novel sensing system using connected pipes to measure bridge deflection in different positions is proposed in this paper. As an absolute reference, the liquid level position along the structure is adopted for the deflection measurement, and an additional external reference to the ground is not needed in this system. The proposed system consists of three parts: connected pipes to connect the measurement points along the structure, liquid to fill in the connected pipes, and the sensing element to detect the change of level. A plastic optical fiber sensor based on the intensity change is used as the sensing element of the developed system. Then, a set of experimental tests are conducted for performance evaluation purposes. Results show that this system has an accurate linear response and high reliability under various environmental conditions. The deflection of the test beam measured by the sensor agrees with linear variable differential transformer (LVDT) within an error margin of 2.1%. The proposed system shows great potential applicability for future health monitoring of long-span bridges.

Effects of epiphytic algae on biomass and physiology of Myriophyllum spicatum L. with the increase of nitrogen and phosphorus availability in the water body.

The disappearance of submerged vascular macrophytes in shallow eutrophic lakes is a common phenomenon in the world. To explore the mechanism of the decline in submerged macrophyte abundance due to the growth of epiphytic algae along a nutrient gradient in eutrophic water, a 2 × 3 factorial experiment was performed over 4 weeks with the submerged macrophyte (Myriophyllum spicatum L.) by determining the plant's biomass and some physiological indexes, such as chlorophyll (Chl) content, malondialdehyde (MDA) content, and superoxide dismutase (SOD) activity in the leaves of M. spicatum L. on days 7, 14, 21, and 28, which are based on three groups of nitrogen and phosphorus levels in the water body (N-P [mg L-1]: NP1 0.5-0.05, NP2 2.5-0.25, NP3 4.5-0.45) and two levels of epiphytic algae (the epiphytic algae group and the control group). Epiphytic algal biomass was also assayed. The results indicated that epiphytic algal biomass remarkably enhanced in the course of the experiment with elevated levels of nitrogen and phosphorus in the water. Under the same level of nutrient condition, plants' biomass accumulation and Chl content were higher in the control group than that in the epiphytic algae group, respectively, while MDA content and SOD activity in the former were lower than that in the latter. The influences of epiphytic algae on the biomass accumulation and Chl content and MDA content became greater and greater with elevated levels of nutrients. In general, in this experiment, water nutrients promoted the growth of both epiphytic algae and submerged plants, while the growth of epiphytic algae hindered submerged macrophytes' growth by reducing Chl content and promoting peroxidation of membrane lipids in plants.

The physiological responses of Vallisneria natans to epiphytic algae with the increase of N and P concentrations in water bodies.

To reveal the mechanism of submerged plants decline in progressively eutrophicated freshwaters, physiological responses of Vallisneria natans to epiphytic algae were studied in simulation lab by measuring plant physiological indexes of chlorophyll content, malondialdehyde (MDA) content, and superoxide dismutase (SOD) activity based on a 2 × 4 factorial design with two epiphytic conditions (with epiphytic algae and without) and four levels of N and P concentrations in water (N-P[mg.L(-1)]: 0.5, 0.05; 2.5, 0.25; 4.5, 0.45; 12.5, 1.25). Compared with control (non-presence of epiphytic algae), chlorophyll contents of V. natans were significantly decreased (p < 0.01) for the presence of epiphytic algae under any concentrations of N and P in water bodies. While the presence of epiphytic algae induced peroxidation of membrane lipids, MDA contents of V. natans had significantly increased (p < 0.05) by comparing with control. SOD activity significantly enhanced (p < 0.05) with the presence of epiphytic algae in the treatments of T2 and T3 in the whole culture process by comparing with control, sometimes reaching an extremely significant level (p < 0.01). However, in the treatments of T1 and T4, SOD activity had no obvious change with the presence of epiphytic algae (p < 0.05) by comparing with control. At the end of the experiment, the effects of epiphytic algae on chlorophyll content and SOD activity in the leaves of V. natans were increased at first and then decreased with the concentrations of N and P in water, and MDA content became higher with the increase of N and P. concentrations. Repeated measurement data testing showed that the effects of epiphytic algae on the chlorophyll content and MDA content and SOD activity were significant, respectively (p < 0.001), the effects of epiphytic algae were combining with effects of concentrations of N and P (p < 0.001), respectively, and their interaction (p < 0.001). Our observations confirmed that this prediction: the growth of epiphytic algae directly produced adverse effects on physiology of V. natans and epiphytic algal biomass were positively correlated with nutrient available in the water column.

[Influences of Potamogeton crispus population on the lake water quality distribution].

A continuing 26-hour monitoring is given on the physical and chemical indicators of the water around the Potamogeton crispus population in Xuanwu Lake, Nanjing City to study the consequent environmental effects. The result shows that both the highest (11.85 mg/L) and the lowest (9.90 mg/L) DO concentrations occur in the population, while the DO concentration decreases with increasing distance from the population. The DO concentration difference of the surface and bottom waters within the population and the open waters is slight, yet it is more obvious in the junction between the population and the open waters. The pH value declines from the population to the open waters. The maximum pH value of the surface water within the population is 10.3, and the minimum value outside the population is 9.2. The pH value of surface water is higher than the bottom within the population, but there is no such difference in the open waters. The TDS content increases with increasing distance from the population, which shows the maximum is 216.9 mg/L of the surface water and the minimum is 177.7 mg/L outside the population. The TDS value of the surface is lower than that in the bottom. The TN, NO2(-) -N, NO3(-) -N contents also increase with the increasing distance from the population, in that the TN content is lower than 2.00 mg/L within the population while the outside is higher than 2.00 mg/L; the NO2(-) -N content is less than 0.026 mg/L within the population while the outside is higher than 0.026 mg/L; the NO3(-) -N content is lower than 1.25 mg/L within the population while the outside is mostly higher than 1.25 mg/L. The TN, NO2(-) -N, NO3(-) -N contents of the surface water are lower than those in the bottom, but the difference is insignificant (p > 0.05). There is no significant difference of the NH4(+) -N content between the inner population and the external and the surface and the bottom. The TP and PO4(3-) -P contents of the surface water are lower than those in the bottom within the population, in that the TP, PO4(3-) -P contents of the highest point of the surface water within the population are 90.9% and 69.64% higher than the lowest point outside the population. The TP and PO4(3-) -P contents of the bottom water are significantly higher than those of the surface within the population, but the difference is slight from outside the population. Therefore, the Potamogeton crispus population plays an important role in improving the lake water quality.