SO2- and H2O-Tolerant Catalytic Reduction of NOx at a Low Temperature via Engineering Polymeric VOx Species by CeO2.

Selective catalytic reduction (SCR) of NOx over V2O5-based oxide catalysts has been widely used, but it is still a challenge to efficiently reduce NOx at low temperatures under SO2 and H2O co-existence. Herein, SO2- and H2O-tolerant catalytic reduction of NOx at a low temperature has been originally demonstrated via engineering polymeric VOx species by CeO2. The polymeric VOx species were tactfully engineered on Ce-V2O5 composite active sites via the surface occupation effect of Ce, and the obtained catalysts exhibited remarkable low-temperature activity and strong SO2 and H2O tolerance at 250 °C. The strong interaction between Ce and V species induced the electron transfer from V to Ce and tuned the SCR reaction via the E-R pathway between the NH4+/NH3 species and gaseous NO. In the presence of SO2 and H2O, the polymeric VOx species had not been hardly influenced, while the formation of sulfate species on Ce sites not only promoted the adsorption of NH4+ species and the reaction between gaseous NO and NH4+ but also facilitated the decomposition of ammonium bisulfate through weakening the strong bond between HSO4- and NH4+. This work provided a new strategy for SO2- and H2O-tolerant catalytic reduction of NOx at a low temperature.

Efficient NOx Abatement over Alkali-Resistant Catalysts via Constructing Durable Dimeric VOx Species.

The presence of alkali metals in flue gas is still an obstacle to the practical application of catalysts for selective catalytic reduction (SCR) of NOx by NH3. Polymeric vanadyl species play an essential role in ensuring the effective NOx abatement for NH3-SCR. However, polymeric vanadyl would be conventionally deactivated by the poison of alkali metals such as potassium, and it still remains a great challenge to construct robust and stable vanadyl species. Here, it was demonstrated that a more durable dimeric VOx active site could be constructed with the assistance of triethylamine, thereby achieving alkali-resistant NOx abatement. Due to the rational construction of polymerization structures, the obtained TiO2-supported cerium vanadate catalyst featured more stable dimeric VOx species and the active sites could survive even after the poisoning of alkali metal. Moreover, the depolymerization of VOx was suppressed endowing the catalysts with more Brønsted and Lewis acid sites after the poisoning of alkali metal, which ensured the efficient NOx reduction. This work unraveled the effects of alkali metal on the polymerization state of active species and opens up a way to develop low-temperature alkali-resistant catalysts for NOx abatement.

Semi-solid extrusion 3D printing ODFs: an individual drug delivery system for small scale pharmacy.

Orodispersible films (ODFs) are promising drug delivery systems for customized medicines as it provide an alternative approach to increase consumer acceptance by advantages of rapid dissolution and administration without water. The aim of this study was to develop a platform to support the realization of tailored treatments suitable for the extemporaneous production of ODFs by semi-solid extrusion (SSE) 3D printing (3DP). Hydroxypropyl methyl cellulose (HPMC) was used as the polymer of ODFs, and levocetirizine hydrochloride was used as the model drug. The optimal formulation was HPMC:API:PS:maltitol:sucralose at a ratio of 64:10:10:15:1. Seventeen percent HPMC solution and optimal formulation were used to prepare film precursors. The impact of dynamic viscosities and fluid mechanics difference on printing applicability was discussed. The ODFs of cube designs with aimed dose of 1.25 mg, 2.5 mg, and 5 mg were printed by SSE 3DP. Good linear relationship between theoretical model volume and drug content (R2 = 0.999) and good dose accuracy indicate that 3DP is a suitable method for preparing individualized ODFs.

Effects of different treatments of the ridge surface on the shear bondstrength between acrylic teeth and thermal polymer resin.

PURPOSE: To evaluate the shear bond strength between denture base and artificial teeth subjected to five different modifications on the ridge surface. METHODS: 30 acrylic central anterior teeth were randomly divided into five groups (n= 6). The ridge surface of these teeth were treated with different methods: (1) No treatment applied; (2) Monomer wetting; (3) Grinding; (4) Grinding followed by sandblasting; (5) Grinding followed by monomer wetting. After the ridge surface of the teeth were treated, they were packed with denture base resin. The shear bond strength between acrylic teeth and denture base resin was performed using a universal testing machine. The data was statistically analyzed using one-way ANOVA (P< 0.05). RESULTS: The monomer wetting group showed the highest shear bond strength values, and the grinding followed by sandblasting group was the lowest, both were statistically significant compared to each other. There were no statistical differences between the other groups. CLINICAL SIGNIFICANCE: Treating the surface of the denture ridge with a monomer provided the highest shear bond strength values, and the grinding followed by sandblasting group was the lowest, statistically significant compared to each other.

Experimental study of the biological properties of nmHA-SiO2 fiber materials prepared by electrospinning technology.

To study the biocompatibility of nanohydroxyapatite (nmHA)-SiO2 fiber material and its efficacy in guided bone regeneration. ① The cytotoxicity of the nmHA-SiO2 fiber material to MC3T3-E1 cells was determined by CCK-8 assay. The adhesion of cells on the surface of the material was observed. ② Bone defects were prepared in the skull of three groups of New Zealand white rabbits. The following treatments were administered: implantation of nmHA-SiO2, implantation of Bio-Oss, and no treatment. The defects were then covered with nmHA-SiO2 membrane or Hai'ao oral repair membrane. Animal samples were analyzed by gross observation, micro-computed tomography, hematoxylin-eosin staining and Masson staining. The data were statistically analyzed by multivariate analysis of variance to evaluate the repair of bone defects. ① The nmHA-SiO2 fiber material has suitable biocompatibility. ② The nmHA-SiO2 fiber material performed more effectively as a barrier membrane than other bone substitute materials in GBR model rabbits.

Enhancement of the degradation capacity of IsPETase for PET plastic degradation by protein engineering.

The enormous waste of polyethylene terephthalate (PET) plastic has a great negative impact on the ecological environment because of its chemical inertia. To reduce the environmental threat posed by PET plastic, researchers gradually concentrate on the biodegradation of PET plastic. In this study, DuraPETaseN233C/S282C/H214S/S245R (DuraPETase-4M) was designed through protein engineering, which can be used to improve the efficiency of PET plastic biodegradation. Based on the DuraPETase, a pair of disulfide bonds (N233C/S282C) was added to improve the thermal stability. Meanwhile, the key region flexibility adjustment (H214S) was proposed to enhance the biodegradation capacity of PET plastic. Additionally, protein surface electrostatic charge optimization (S245R) was adopted to improve the binding ability between enzyme and PET plastic. Based on molecular dynamic simulations (MDs), the rationality of the design was further verified. This study provides a strategy for obtaining high-efficiency PET degradation mutants and a new possibility of environmentally friendly plastic degradation.

Amphiphilic bromelain-synthesized oligo-phenylalanine grafted with methoxypolyethylene glycol possessing stabilizing thermo-responsive emulsion properties.

A thermo-responsive amphiphile was developed from oligo-phenylalanine [oligo(Phe)]. The hydrophobic moiety of the amphiphile, oligo(Phe) was synthesized via reverse hydrolysis catalyzed by bromelain in dimethyl sulfoxide and dioxane solutions. The production of oligo(Phe) increased by 80.7% by screening suitable reaction conditions. The average degree of polymerization of oligo(Phe) was determined to be four by 1H NMR. By grafting with aldehyde-ended methoxypolyethylene glycol (mPEG), oligo(Phe) was converted to amphiphilic oligo(Phe)-mPEG. The surface tension of oligo(Phe)-mPEG solution increased with decreasing chain length of the mPEG moiety. Cytotoxicity studies showed oligo(Phe)-mPEGs are biocompatible. On varying temperature, a reversible phase transition of oligo(Phe)-mPEG solutions could be observed. N-octane-in-water emulsions and 0.5% beta-carotene containing squalene-in-water emulsions stabilized by oligo(Phe)-mPEGs occurred at 25 °C but de-emulsification took place at >40 °C. Emulsification could be restored once the separated mixture cooled and re-homogenized. The emulsification/de-emulsification cycling could be repeated many times. The time required for de-emulsification decreased with elevated temperature but increased with a reduced concentration of oligo(Phe)-mPEGs and a reduction in the chain length of the mPEG moiety.

[Single cell gel electrophoresis of a magnesium alloy coated with beta-tricalcium phosphate].

OBJECTIVE: To evaluate the genotoxicity of a magnesium alloy coated with beta-tricalcium phosphate (beta-TCP). METHODS: Four groups were designed. In the first group, AZ31B magnesium alloy surface was coated with beta-TCP using chemical bath deposition, and in the second group magnesium alloy was tested. The other two groups were negative control (pure titanium) and positive control groups (0.5 mg/L bleomycin). Single cell gel electrophoresis was adopted to investigate genotoxicity of the alloy samples in different groups, and 60 cells from each group were analysed. Tail moment and tail DNA percentage were used as reliable indicators to show DNA damage in lymphocytes induced by every testing sample. Student-Newman-Keuls (SNK) test was used to compare results from 4 groups. RESULTS: There were no significant differences in tail moment and tail DNA percentage between magnesium alloy group [(0.52 +/- 0.12), (6.82 +/- 1.81)%] and magnesium alloy coated with beta-TCP group [(0.51 +/- 0.12), (6.89 +/- 1.93)%, P > 0.05]. Tail moment and tail DNA percentage in negative group were (0.47 +/- 0.14) and (6.29 +/- 1.64)%, and tail moment and tail DNA percentage in positive group were (5.17 +/- 1.23) and (22.09 +/- 4.51)%. CONCLUSIONS: No significant increase was found in DNA damage in lymphocytes induced by magnesium alloy coated with beta-TCP.