Dispersion Engineering of Silicon Nitride Microresonators via Reconstructable SU-8 Polymer Cladding.

In this work, we propose a novel way to flexibly engineer the waveguide dispersion by patterning the cladding of waveguide microresonators. Experimentally, we demonstrate silicon nitride waveguides with air-, oxide-, and SU-8 polymer-cladding layers and compare the corresponding waveguide dispersion. By integrating SU-8 polymer as the outer cladding layer, the waveguide dispersion can be tuned from -143 to -257 ps/nm/km. Through the simple, conventional polymer stripping process, we reconstruct the waveguide dispersion back to that of the original air-cladded device without significantly impacting the quality factor of resonators. This work provides the potential to design the waveguide dispersion in normal and anomalous regimes within an integrated photonic circuit.

[Effect of Enteromorpha prolifera Biochar on the Adsorption Characteristics and Adsorption Mechanisms of Ammonia Nitrogen in Rainfall Runoff].

In order to study the performance and mechanisms of bioretention pond media (Enteromorpha prolifera biochar) for NH4+-N removal in rainfall runoff, three kinds of alkali modified biochars (marked as BC1, BC2, and BC3) were prepared with various concentrations of NaOH solution (1, 2, and 3 mol·L-1) to explore their adsorption performance for NH4+-N. The results showed that:① Appropriate modifications of the NaOH concentration increased the specific surface area and surface microstructure of biochar, with the content of O and the surface functional groups being enriched. In addition, BC2 possessed the best adsorption performance. ② The adsorption capacity reached a maximum when the pH was 9.0 and the dosage of biochar was 0.5 g·L-1. Compared with BC, the adsorption capacity of BC1 and BC2 increased by 6.4% and 10.8%, respectively, while BC3 decreased by 13.7%. Moreover, BC2 had an optimal adsorption efficiency with a saturated adsorption capacity of 16.76mg·g-1. ③ The adsorption mechanism of biochar belonged to chemical adsorption with a monomolecular layer. The adsorption process was promoted by the high pH of biochar, the electrostatic attraction of biochar pores, the complexation and oxidization of the functional groups of hydroxyl (-OH), carboxyl (-COOH), and carbon-oxygen single bond (C-O). To sum up, the proper amount of NaOH to modify biochar can improve the adsorption performance of NH4+-N, and the modified biochar can be used as media of the bioretention pond to remove NH4+-N.

[Effect and Approach of Enteromorpha prolifera Biochar to Improve Coastal Saline Soil].

The use of biochar to improve adversity of soil has received increasing attention. Enteromorpha prolifera biochar is used to repair coastal saline-alkali soil, which can not only utilize Enteromorpha prolifera but can also increase the scale of the coastal land reserve. In this study, the method of soil culture experiments was used to explore the effect and pathway of 0%-3% addition of Enteromorpha prolifera on the improvement of saline-alkali soil. The results showed that the optimum preparation temperature of Enteromorpha prolifera biochar suitable for saline-alkali soil improvement was 400℃, and the optimum addition amount was 1.5%. At the optimum level, although the biochar had a negative effect, such as increasing soil salinity (0.12%) and pH (1.49%), it also produced positive effects, such as reducing soil Na+/K+ by 55.73%, increasing mineral content, and improving water conductivity. Enteromorpha prolifera biochar improved soil physicochemical and biological properties, increased nutrient content, enhanced microbial activity, improved soil nutrient availability, and produced positive effects. These positive effects were characterized by reducing soil bulk density by 11.35%, increasing organic matter by 42.64%, increasing the proportion of organic carbon in total carbon by 3.84 times, increasing the proportion of available phosphorus in total phosphorus by 4.15 times, and increasing soil invertase activity by 2.39 times, urease activity by 1.18 times, and catalase activity 1.50 times. Therefore, the positive effect of Enteromorpha prolifera biochar on saline-alkali soil is more than negative, and it can be used for the improvement of coastal saline-alkali soil. This study provides a new path for the resource utilization of Enteromorpha prolifera and the improvement of the ecological environment of coastal saline-alkali soil.

[Water Purification Effect and Saline-alkali Tolerance Improvement Mechanism of Suaeda salsa in the Estuary Area].

The pollution load of nitrogen and phosphorus in pollutants entering the sea is high, which seriously affects the water quality of coastal water. It is necessary to strengthen land-sea coordination. However, affected by the seawater encroachment, the salt and alkali content of the water in the estuary area is high and the variation range is large, which leads to difficulty in plant growth. The ability of plants to remove nitrogen and phosphorus is reduced. How to improve the survival ability of plants is an urgent problem to be solved. In this study, the addition of appropriate concentrations of Ca2+ and K+ can improve the salinity tolerance of plants and reduce the risk of eutrophication. The results showed that under the condition of pH 8 and salinity 20‰, the removal efficiency of total nitrogen and total phosphorus was the highest in the hydroponic experiment with exogenous Ca2+ and K+ concentrations of 8mmol·L-1 and 10mmol·L-1 respectively, which were 1.53-1.87 times those in the control group. At this time, the growth rate of Suaeda salsa was the best, and the maximum relative growth rates (RGR) were 2.4 times and 2.0 times that of the control group, respectively. The remission effect of Ca2+ was greater than that of K+ at the same concentration. The mechanism by which exogenous Ca2+ and K+improve the salt-alkali tolerance ability of Suaeda salsa was mainly manifested as improving osmotic regulation ability. In the aspect of inorganic osmotic regulation, exogenous ions improved the water-holding capacity of the plant, among which the correlation coefficients of inorganic ion content and water content in leaves and roots were all above 0.966. In terms of organic osmotic regulation, exogenous Ca2+ and K+ all promoted the accumulation of small molecular organic compounds such as betaine in Suaeda salsa, and alleviated plasma membrane peroxidation in leaves. Among them, the largest reductions of malondialdehyde content in leaves were 72.9% and 61.7%, respectively. Therefore, exogenous Ca2+ and K+can enhance the osmotic adjustment ability and promote the growth of Suaeda salsa, thereby improving the removal rate of nitrogen and phosphorus. The results provide a theoretical basis for improving the water purification effect and reducing eutrophication risk in coastal waters.

Piriformospora indica promotes growth, seed yield and quality of Brassica napus L.

In current scenario, crop productivity is being challenged by decreasing soil fertility. To cope up with this problem, different beneficial microbes are explored to increase the crop productivity with value additions. In this study, Brassica napus L., an important agricultural economic oilseed crop with rich source of nutritive qualities, was interacted with Piriformospora indica, a unique root colonizing fungus with wide host range and multifunctional aspects. The fungus-treated plants showed a significant increase in agronomic parameters with plant biomass, lodging-resistance, early bolting and flowering, oil yield and quality. Nutritional analysis revealed that plants treated by P. indica had reduced erucic acid and glucosinolates contents, and increased the accumulation of N, Ca, Mg, P, K, S, B, Fe and Zn elements. Low erucic acid and glucosinolates contents are important parameters for high quality oil, because oils high in erucic acid and glucosinolates are considered undesirable for human nutrition. Furthermore, the expression profiles of two encoding enzyme genes, Bn-FAE1 and BnECR, which are responsible for regulating erucic acid biosynthesis, were down-regulated at mid- and late- life stages during seeds development in colonized plants. These results demonstrated that P. indica played an important role in enhancing plant growth, rapeseed yield and quality improvement of B. napus.

[Purification of Slightly Salt-alkaline Water Bodies by Microorganism Enhanced Combined Floating Bed].

In order to study the purifying effect of combined floating bed constucted by salinity plant Suaeda salsa and microorganisms on the slightly salt-alkaline water, blank floating bed A, S.salsa floating bed B, microbes floating bed C and S.salsa + microorganisms combined floating bed D were established, and slightly salt-alkaline eutrophic water body (pH 8.5-9.0, salinity 5‰-7‰) was purified under continuous flow conditions in the laboratory. Results showed that the removal rates of total nitrogen, total phosphorus, permanganate index by S.salsa floating bed were 32.5%, 14.3% and 28.2%, respectively. And the removal rates of total nitrogen, total phosphorus and permanganate index by S.salsa + microorganisms combined floating bed D which installed artificial medium with microorganisms reached 70.5%, 34.7% and 70.8%, respectively, of which the removal rates of total nitrogen, total phosphorus and permanganate index by microbial units were 37.7%, 21.6% and 44.5%, respectively. Synergies removal rates of nitrate nitrogen and total nitrogen by S.salsa + microorganisms combined floating bed were 12.2% and 0.3%, but there was no synergy in the process of removing ammonia nitrogen, total phosphorus and permanganate index, which indicated that the synergies of S.salsa and microorganisms in the combined floating bed were suppressed in slightly salt-alkaline environment. The high-throughput sequencing technique was adopted to analyze the microbial community in the floating bed C and D, which indicated that the abundance and diversity of microbial community in the combined floating bed were higher, and this was consistent with the result of the higher removal rate of the flotation bed D. Principal component analysis showed that the microbial degradation was a major factor in reducing the concentration of pollutants. This study provided a guide for the using of floating bed in purifying slightly salt-alkaline eutrophic water bodies in coastal area.

[Characteristics of Enteromorpha prolifera Biochars and Their Adsorption Performance and Mechanisms for Cr(â ¥)].

This study aims to understand the recycling process of Enteromorpha prolifera by using the slow pyrolysis technology to prepare biochars under different temperatures and by characterizing the physicochemical properties of biochars. The results showed that a relatively high level pyrolysis of Enteromorpha prolifera could be reached when the temperature was up to 400℃. The yield rate and the ash content of biochars were negatively correlated with the pyrolysis temperature, while the carbon content was positively correlated. The specific surface area of Enteromorpha prolifera biochars was in the range of 44.54-317.82 m2·g-1. The biochar surface was in the shape of a honeycomb and rich in oxygen-containing functional groups, such as hydroxyl (-OH) and carboxyl (-COOH) groups. The adsorption experiments revealed that the adsorption of Cr(Ⅵ) onto Enteromorpha prolifera biochars followed the pseudo-second-order kinetics equation and Langmuir isotherm, indicating that the adsorption process was controlled by the fast reaction process and governed by monomolecular and chemical adsorption. The optimal pH for Cr(Ⅵ) adsorption onto Enteromorpha prolifera biochars was 2 and their adsorption capabilities were in the order of BC400 > BC700 > BC600 > BC500 > BC300 (the adsorption capacity of BC400 was 4.79 mg·g-1). The adsorption mechanism included the electrostatic interactions between biochar and anions (HCrO-4 and Cr2O2-7) and the complexation of oxygen-containing functional groups.

[Characterization of Cr Tolerance and Accumulation in Lolium perenne L. and Pharibitis purpurea(L.) Voigt].

Considering the serious pollution of heavy metal-chromium (Cr) in soil, there is an urgent need for effective selection of Cr-tolerant plant species. In order to gain fundamental insights into the tolerance and accumulation capabilities of Lolium perenne L. and Pharibitis purpurea(L.) Voigt under Cr stress, a pot experiment was conducted to investigate their growth, physiology and accumulation characteristics under Cr(Ⅲ) and Cr(Ⅵ) stress. The results showed the growth parameters could intuitively reflect the toxicity levels of Cr for plants. For instance, a low-level Cr(Ⅲ) (<250 mg·kg-1) in soil was good for plant growth as indicated by the significant elevation of plant height, root length and biomass in L. perenne (P<0.05). However, Cr(Ⅵ) at all concentrations (≥25 mg·kg-1) in the soil inhibited the growth of both plant species, and the root length was particularly sensitive to the toxicity of Cr. The physiological parameters of plant represented both the toxicity of Cr and the tolerance of plants under Cr stress. A decrease of root activity and an increase of malonaldehyde content were observed under Cr stress, which indicated the physiological metabolism of plants was disturbed. In the presence of both Cr species, the proline content increased, which served as an indicator for both high Cr toxicity and increase of osmotic balance in plants. A rise in SOD and POD activity reflected the defense ability of plants against oxidative stress caused by Cr. In addition, the Cr-accumulation related parameters were the major standards for tolerant species selection. The Cr(Ⅵ) accumulation capacities of both plant species were greater than their Cr(Ⅲ) accumulation capacities. The maximum accumulation amounts of L. perenne and P. purpurea reached 957.4 mg·kg-1 and 743.3 mg·kg-1 in roots and 394.7 mg·kg-1 and 340.4 mg·kg-1 in shoots, respectively. In comparison with P. purpurea, L. perenne displayed a stronger Cr accumulation capacity in roots with a maximum bioaccumulation factor of 15.55. However, the transport ability of P. purpurea was superior to L. perenne. All of the parameters demonstrated that both L. perenne and P. purpurea could be used as alternative plants for phytoremediation of Cr-contaminated soil.

[A Contrastive Study on Salt-alkaline Resistance and Removal Efficiency of Nitrogen and Phosphorus by Phragmites australis and Typha angustifolia in Coastal Estuary Area].

The salt and alkali contents were so high that the ecological landscape was depressed in water body of a coastal estuary area. Screening some plants which could not only tolerate saline-alkaline but also effectively remove nitrogen and phosphorus was therefore in urgent need. The tolerance range and removal rate of nitrogen and phosphorus by Phragmites australis and Typha angustifolia under salt and pH stress were investigated by hydroponic experiments. The results showed that Phragmites australis could tolerate at least 10 per thousand salinity and pH 8.5, while Typha angustifolia tolerated 7.5 per thousand salinity and pH 8.0. Combined with the change of the growth and physiological indexes (relative conductivity, proline, chlorophyll and root activity), the salt resistance of Phragmites australis was stronger than that of Typha angustifolia. Under salt stress, the removal rate of ammonia nitrogen of Phragmites australis was higher. The removal rates of nitrate nitrogen and phosphorus of Typha angustifolia were 2.5% and 7.3% higher than those of Phragmites australis in average, respectively, because of the high biomass of Typha angustifolias. The total nitrogen removal rate was equivalent. Under pH stress, the removal rate of ammonia nitrogen and total phosphorus of Phragmites australis was a little higher than that of Typha angustifolia. However, Typha angustifolia had a higher removal rate of total nitrogen, which was 8.2% higher than that of Phragmites australis. All the analysis showed that both Phragmites australis and Typha angustifolia could be used as alternative plants to grow and remove nitrogen and phosphorus in the high salt-alkaline water body in coastal estuary area.

[Variation of nitrogen during the high suspended sediments concentration water supply in an artificial shallow lake].

The effect of water quality and suspended sediments in the process of water supply is of an increasing concern recently in an artificial shallow lake. The water supply from the Yellow River to Dongchang Lake happened on April 23rd to 25th, 2012. The synchronous monitoring of flow velocity, suspended sediment concentration, dissolved nitrogen and particulate nitrogen concentration was conducted during the three days in five monitoring sites of the longitudinal profile from inlet to outlet. The spatio-temporal variation of nitrogen and the relationship between nitrogen concentration and suspended sediment concentration was analyzed. Moreover, the analysis of different nitrogen forms in surface water and bottom sediment was also made in the whole lake before and after the water supply. Results showed that the process of water supplement had an obvious effect on flow velocities and suspended sediment concentrations around the inlet area. The influence area was a limited scope. The spatial distribution of nitrogen presented a certain concentration gradient along the flow direction. Around the water inlet, concentrations of all nitrogen forms in water and bottom sediment was higher than those in other lake zones. The amplitude of variation of all nitrogen concentrations in surface water, suspended sediments showed a decreasing trend from water inlet to outlet. And concentrations of total dissolved and particulate nitrogen increased at different ratios after water supply in the lake. Total particulate nitrogen concentration increase was higher. It revealed the water supply of the Yellow River had a great influence on lake water. The dissolved nitrogen was the main nitrogen form in water supply. The ratio of total dissolved nitrogen to particulate nitrogen was 7.3 : 1. Nitrate was the primary form in dissolved nitrogen, and ammonium was the primary form in particulate nitrogen, respectively. The correlation between concentration of suspended sediments and ammonium, total nitrogen were notable during te water supply, the correlation coefficient were 0.868 and 0.876. Ammonium was mainly influenced by water supply and adsorption and precipitation of suspended sediments. However, the concentration of nitrate was not influenced. Organic nitrogen was the main form in bottom sediment. It meant that the Yellow River water and suspended sediments were the input sources of nitrogen to Dongehang Lake.

Role of the reduction site in the fluorinated or sulfated TiO2 photocatalytic process.

In this article, the effects of TiO2 surface fluorination and sulfation, on the active oxygen species formed at the reduction site in the photocatalytic process, namely O2*- and H2O2, were investigated from a new perspective. The superoxide radical, (O2*-), was determined by colorimetry of nitroblue tetrazolium, a prominent O2*- scavenger. Hydrogen peroxide (H2O2) was estimated by using the iodide-starch method. In the naked TiO2 photocatalysis, O2*-, though less reactive, was a very important intermediate. When the TiO2 surface was fluorinated, more O2*- and H2O2 were produced, which indicated that the surface modification could greatly reduce the recombination of photogenerated electrons and holes, thus enhancing the photocatalytic rate. In the sulfated system, photocatalysis proceeded with a more complicated mechanism. These results added support to the view of fluoride-induced enhancement and sulfide's nonappreciable inhibition effect.

Enhanced photocatalytic activity of TiO2 by surface fluorination in degradation of organic cationic compound.

Experiments were carried out to investigate the influence of TiO2 surface fluorination on the photodegradation of a representative organic cationic compound, Methylene Blue (MB). The electropositive MB shows poor adsorption on TiO2 surface; its degradation performs a HO-radical-mediated mechanism. In the F-modified system, the kinetic reaction rate enlarged more than 2.5 fold that was attributed mainly to the accumulating adsorption of MB and the increased photogenerated hole available on the F-modified TiO2 surface.