[Comparative Phosphorus Accumulation and Ca-P Content of Two Submerged Plants in Response to Light Intensity and Phosphorus Levels].

The micro-environment formed by the photosynthesis of submerged plants is conducive to the formation of CaCO3-P from co-precipitation of calcium and phosphorus in water, thereby permanently removing phosphorus from water to the bottom mud and avoiding secondary pollution after plants decay. However, CaCO3-P co-precipitation shows obvious specific-differences and environmental dependencies. In the present study, two different submerged plants, Myriophyllum aquaticum and Potamogeton crispus, were used as the research objects. Two variables, inorganic phosphorus level (0, 0.2, and 2 mg·L-1) and light intensity [66 µmol·(m2·s)-1 and 110 µmol·(m2·s)-1], were set. After cultivating for a week, the plant relative growth rate, plant total phosphorus, plant ash phosphorus, and Ca-P were measured to analyze the actual ability of phosphorus accumulation and clarify the effect of plant corruption on phosphorus increase in the water body. Results revealed that under various culture conditions, the relative growth rates (RGR) of P. crispus were significantly higher than those of M. aquaticum, and RGR reached the maximum at a P level of 2 mg·L-1 and a light intensity of 66 µmol·(m2·s)-1. The addition of inorganic phosphorus significantly affected plant ash phosphorus of the two plants (P. crispus 95.681%, M. aquaticum 85.432%), and the highest value of Ca-P content in the ash phosphorus of the two submerged plants appeared at a high phosphorus level. The total phosphorus in P. crispus was lower than that in M. aquaticum under various treatments, but the total ash phosphorus and Ca-P levels were higher than those in M. aquaticum. Consequently, M. aquaticum and P. crispus can effectively accumulate phosphorus during growth. However, the actual ability of P. crispus of removing phosphorus from water by the formation of CaCO3-P was higher than that of M. aquaticum at a P level of 2 mg·L-1.

The synthesis and antistaphylococcal activity of dehydroabietic acid derivatives: Modifications at C-12.

A series of 12-oxime and O-oxime ether derivatives of dehydroabietic acid were synthesized and investigated for the antibacterial activity against Staphylococcus aureus Newman strain and five multidrug-resistant strains (NRS-1, NRS-70, NRS-100, NRS-108, and NRS-271). The aromatic oximate derivative 11a showed the highest activity with MIC of 0.39-0.78µg/mL against S. aureus Newman. Of note, compounds 10b, 11 and 14 showed the most potent antibacterial activity against five multidrug-resistant S. aureus with MIC values of 1.25-3.13µg/mL. These results offered useful information for further strategic optimization in search of the antibacterial candidates against infection of multidrug-resistant Gram-positive bacteria.

pH-responsive controlled-release fertilizer with water retention via atom transfer radical polymerization of acrylic acid on mussel-inspired initiator.

This work reports a polydopamine-graft-poly(acrylic acid) (Pdop-g-PAA)-coated controlled-release multi-element compound fertilizer with water-retention function by a combination of mussel-inspired chemistry and surface-initiated atom transfer radical polymerization (SI-ATRP) techniques for the first time. The morphology and composition of the products were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), gel permeation chromatography (GPC), and inductively coupled plasma (ICP) emission spectrometry. The results revealed that the stimuli-responsive layer formed by a Pdop inner layer and a PAA outer corona exhibit outstanding selective permeability to charged nutrients and the release rate of encapsulated elements can be tailored by the pH values. At low pH, the Pdop-g-PAA layer can reduce nutrient loss, and at high pH, the coating restrains transportation of negative nutrients but favors the release of cations. Moreover, PAA brushes provide good water-retention property. This Pdop-graft-polymer brushes coating will be effective and promising in the research and development of multi-functional controlled-release fertilizer.

Polydopamine film coated controlled-release multielement compound fertilizer based on mussel-inspired chemistry.

This work reports on a facile and reliable method to prepare a polydopamine film coated controlled-release multielement compound fertilizer (PCMCF) based on mussel-inspired chemistry for the first time. The polydopamine (Pdop) film was coated on double copper potassium pyrophosphate trihydrate, providing three essential nutrients (Cu, K, and P) by spontaneous oxidative polymerization of dopamine. The thickness of the polymer coating of the fertilizer was controlled by using the multistep deposition technique. The morphology and composition of the products were characterized by transmission electron microscopy, inductively coupled plasma emission spectrometer, a vis spectrophotometer, and a Kjeltec autoanalyzer. The controlled-release behavior of four elements, including nitrogen from Pdop, was evaluated in water and in soil (sterilized or not). The results revealed that the coated fertilizers had good slow-release properties, incubated in either water or soil. It is noted that the release rate of nutrients of PCMCF can be tailored by the thickness of the Pdop coating, and the Pdop coating can be biodegraded in soil. This coating technology will be effective and promising in the research and development of controlled-release fertilizer.