Enhanced Long-Term Nitrogen Removal and Its Quantitative Molecular Mechanism in Tidal Flow Constructed Wetlands

Tidal flow constructed wetlands (TF CWs) have recently been studied as a sustainable technology to achieve enhanced nitrogen removal; however, the underlying mechanisms responsible for removing ammonium (NH₄⁺) and nitrate (NO₃^–) have not been compared and quantified at the molecular level (genes) in controlled TF CWs. In this study, two TF CWs T1 (treating NH₄⁺ wastewater) and T2 (treating NO₃^– wastewater) achieved high removal efficiencies for chemical oxygen demand (COD, 92 ± 2.7% and 95 ± 2.4%, respectively), NH₄⁺/NO₃^– (76 ± 3.9% and 97 ± 2.2%, respectively), and total nitrogen (TN, 81 ± 3.5% and 93 ± 2.3%, respectively). Combined analyses revealed that the presence of simultaneous nitrification, anammox, and denitrification processes and the coupling of dissimilatory nitrate reduction to ammonium, ammonia oxidation, and anammox were the primary reason accounted for the robust treatment performance in T1 and T2, respectively. Results from stepwise regression analysis suggested that the NH₄⁺ removal rate in T1 was collectively controlled by <i>amo</i>A, <i>nxr</i>A, and anammox, while the NO₃^– removal rate in T2 was governed by <i>nxr</i>A and <i>nar</i>G gene

High Performance Miscible Polyetherimide/Bismaleimide Resins with Simultaneously Improved Integrated Properties Based on a Novel Hyperbranched Polysiloxane Having a High Degree of Branching

Amino-terminated hyperbranched polysiloxane (AHBSi) with high degree of branching (= 0.8) was synthesized by a control hydrolysis of γ-aminopropyl triethoxysilane (APTES) without using any catalyst. Besides, AHBSi was used as the compatibilizer of the miscible polyetherimide (PEI)/bismaleimide (BD) blend, and the influence of the content of AHBSi on the compatibility and integrated performance of the PEI/BD blend was systematically investigated. The corresponding investigation of the APTES/PEI/BD system was also carried out for comparison. Results show that although AHBSi and APTES have similar chemical segments, their different topological structures endow them with completely different effects. AHBSi can remarkably improve the compatibility between PEI and BD resin, and the AHBSi/PEI/BD system not only has obviously improved toughness and decreased brittleness while maintaining good stiffness. It also exhibits decreased dielectric constant and loss. Conversely, the APTES/PEI/BD system has greatly deteriorated compatibility and integrated performance. These interesting results demonstrate that AHBSi is a super multifunctional compatibilizer

Preparation of End-Capped Hyperbranched Polyaniline@Carbon Nanotube Hybrids for High‑<i>k</i> Composites with Extremely Low Percolation Threshold and Dielectric Loss

How to greatly decrease the dielectric loss while maintaining extremely low percolation threshold (<i>f</i>_c) is the main target of developing high-<i>k</i> conductor/polymer composites. Here, novel hybridized multiwalled carbon nanotubes (MWCNTs) with coated end-capped hyperbranched polyaniline (EHSiPA), EHSiPA@MWCNT, were developed and embodied into epoxy (EP) resin to produce new high-<i>k</i> composites. Systematic investigations of the structure and dielectric properties showed that the <i>f</i>_c of EHSiPA@MWCNT/EP composites is as low as 0.41 wt %; in addition, EHSiPA@MWCNT/EP composites with suitable loadings of EHSiPA have much higher dielectric constants and lower dielectric losses than the MWCNT/EP composite. Specifically, the dielectric constant and loss at 100 Hz for [email protected]/EP are 1.4 and 6.8 × 10^–3 times the values for the MWCNT0.4/EP composite, respectively. To reveal the origin of this, the distributions of space charges of EHSiPA@MWCNT/EP composites are discussed. This investigation suggests that designing and preparing new conductors with unique structures may provide a way to fabricate high-<i>k</i> composites

A New Scalable Route to 4‑(2-Hydroxyethyl)-1,3-dihydro‑2<i>H</i>‑indol-2-one: A Key Intermediate for Ropinirole Hydrochloride

A new and efficient manufacturing technology is disclosed in the present work for the preparation of 4-(2-hydroxyethyl)-1,3-dihydro-2<i>H</i>-indol-2-one, which is a key intermediate for ropinirole hydrochloride. The whole process gives the target molecule in 71% overall yield with 99% purity. In the final step, a novel nitro reduction/ring-closing/debenzylation takes place in one pot. All the intermediates can be used directly for the next step without purification in this process

Flame Retarding Cyanate Ester Resin with Low Curing Temperature, High Thermal Resistance, Outstanding Dielectric Property, and Low Water Absorption for High Frequency and High Speed Printed Circuit Broads

High-end electric products require high frequency and high speed printed circuit broads (HFS-PCBs), while high performance resin is the key for fabricating HFS-PCBs. A new resin system (DPDP/CE) was developed by copolymerizing 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DPDP) and 2,2′-bis­(4-cyanatophenyl) propane (CE). Compared with CE resin postcured at 250 °C for 4 h, the DPDP/CE system that was only postcured at 220 °C for 2 h has outstanding flame retardancy, greatly reduced water absorption, low dielectric loss, and high thermal resistance. For DPDP1.4/CE resin with 1.4 wt % phosphorus content, its dielectric constant and loss at 1 GHz are 2.71 and 0.005, respectively, and hardly change after staying in boiling water for 100 h. Different from UL-94 V-2 rating of CE resin, the flame retardancy of DPDP1.4/CE resin is desirable UL-94 V-0 rating, resulting from both gas-phase and condensed-phase mechanisms. These attractive features suggest that the DPDP/CE system is suitable to fabricate HFS-PCBs for high-performance electric products

Multifunctional Cyclotriphosphazene/Hexagonal Boron Nitride Hybrids and Their Flame Retarding Bismaleimide Resins with High Thermal Conductivity and Thermal Stability

A novel hybridized multifunctional filler (CPBN), cyclotriphosphazene/hexagonal boron nitride (hBN) hybrid, was synthesized by chemically coating hBN with hexachlorocyclotriphosphazene and p-phenylenediamine, its structure was systemically characterized. Besides, CPBN was used to develop new flame retarding bismaleimide/<i>o</i>,<i>o</i>′-diallylbisphenol A (BD) resins with simultaneously high thermal conductivity and thermal stability. The nature of CPBN has a strong influence on the flame behavior of the composites. With the addition of only 5 wt % CPBN to BD resin, the thermal conductivity increases 2 times; meanwhile the flame retardancy of BD resin is remarkably increased, reflected by the increased limited oxygen index, much longer time to ignition, significantly reduced heat release rate. The thermogravimetric kinetics, structures of chars and pyrolysis gases, and cone calorimeter tests were investigated to reveal the unique flame retarding mechanism of CPBN/BD composites. CPBN provides multieffects on improving the flame retardancy, especially in forming a protective char layer, which means a more thermally stable and condensed barrier for heat and mass transfer, and thus protecting the resin from further combustion

New Bismaleimide Resin Toughened by In Situ Ring-Opening Polymer of Cyclic Butylene Terephthalate Oligomer with Unique Organotin Initiator

A new organotin initiator with amino-terminated hyperbranched polysiloxane (HSiSn) for the ring-opening polymerization of cyclic butylene terephthalate (CBT) oligomer was synthesized. Compared with a traditional initiator, butyltin chloride dihydroxide (BCD), HSiSn has a moderate initiate speed, lower toxicity, and good reactivity. Poly­(butylene terephthalate) (PBT) is the ring-opening polymer of CBT, of which the crystalline and molecular weight are almost independent of the initiator used, but the PBT initiated by HSiSn has better thermal stability than that by BCD. On this basis, a series of new toughened bismaleimide (BD) resins (HSiSn/CBT-BD) were prepared through the in situ formation of PBT during the prepolymerization of BD resin with HSiSn. Compared with BCD/CBT-BD and BD resins, HSiSn/CBT-BD resins with small loadings of CBT (≤5 wt %) have remarkably improved integrated performances, including higher impact strengths, improved flexural, and tensile properties, better dielectric properties, and excellent heat resistance. These attractive performances are attributed to the unique cross-linked structure induced by HSiSn

Facile Preparation and Origin of High‑<i>k</i> Carbon Nanotube/Poly(Ether Imide)/Bismaleimide Composites through Controlling the Location and Distribution of Carbon Nanotubes

The morphology (location and distribution) of conductive fillers in conductive filler/polymer nanocomposites has a decisive influence on dielectric properties of a composite, so with the same components, how to facilely control the morphology of nanofillers, build its relationship with dielectric properties of the composite, and clearly reveal the origin behind are still interesting challenges. Herein, a fixed loading (0.4 wt %) of multiwalled carbon nanotubes (MWCNTs) was embodied into an incompatible poly­(ether imide) (PEI)/bismaleimide (BD) system to prepare a series of composites (0.4MWCNT/PEI/BD). As the PEI content increases, the structure of composite successively changes from sea-island to cocontinuous phase and phase inversion. More interestingly, MWCNTs prefer to selectively distribute in the BD phase, tend to enrich around the PEI dense zone, and arrange normally to the radius of the PEI sphere zone, so the morphology of MWCNTs and thus dielectric properties of composites can be facilely controlled. The dielectric constant and loss of 0.4MWCNT/PEI/BD composite with 10 wt % PEI are about 4.5 and 0.1 times the values of 0.4MWCNT/BD composite, respectively, overcoming the critical problem of available conductive filler/polymer composites. Different equivalent circuits were built for these composites, revealing the origin behind the method developed herein for controlling unique dielectric properties of 0.4MWCNT/PEI/BD composites

A Molecular Diode with a Statistically Robust Rectification Ratio of Three Orders of Magnitude

This paper describes a molecular diode with high, statistically robust, rectification ratios <i>R</i> of 1.1 × 10³. These diodes operate with a new mechanism of charge transport based on sequential tunneling involving both the HOMO and HOMO–1 positioned asymmetrically inside the junction. In addition, the diodes are stable and withstand voltage cycling for 1500 times, and the yield in working junctions is 90%

Water-Phase Synthesis of a Biobased Allyl Compound for Building UV-Curable Flexible Thiol–Ene Polymer Networks with High Mechanical Strength and Transparency

Using water as a reaction medium to synthesize biobased monomers with high renewable carbon content for preparing biobased polymers is of great importance for environmental protection and sustainable development. Herein, a trifunctional allyl compound, tris­(4-allyl-2-methoxyphenyl) phosphate (TAMPP) with 100% renewable carbon content was synthesized from renewable eugenol through one-step method using water as the solvent. TAMPP was then used to prepare flexible and transparent thiol–ene polymer networks TAMPP-SH via solvent-free thiol–ene “click” photopolymerization with various multifunctional thiols. The influences of the thiol functionality from 2 to 4 on structure and integrated performances were systematically researched. Among them, TAMPP-SH4 shows the best thermal and mechanical properties. Specifically, its glass transition temperature (<i>T</i>_g) is as high as 35 °C, while its tensile strength and modulus are as high as 19.8 ± 0.6 MPa and 601.6 ± 22.4 MPa, respectively. At the same time, it still maintains high flexibility. The nature behind these outstanding integrated performances is attributed to the unique structure of TAMPP, which is rich in aromatic structure, and the very high cross-linking density of TAMPP-SH4 network. The especially high renewable carbon content and outstanding thermal and mechanical performances clearly show that the TAMPP-SH4 network has great potential in fabricating flexible products