Engineering MXene surface with POSS for reducing fire hazards of polystyrene with enhanced thermal stability.

High-performance MXene-based polymer nanocomposites are highly desirable for diverse industry applications due to their exceptional mechanical, thermal and other properties. Nevertheless, it remains an intractable challenge to create flame retardant polymer/MXene nanocomposites due to the difficulty to achieve uniform dispersion of MXenes. Here, we reported a facile strategy for the surface manipulation of two-dimensional titanium carbide nanosheets (Ti3C2Tx) with 3-aminopropylheptaisobutyl-polyhedral oligomeric silsesquioxane (AP-POSS) (POSS-Ti3C2Tx) through electrostatic interactions. The POSS-Ti3C2Tx is steadily dispersed in many polar solvents. Upon incorporated into polystyrene (PS), the combined effect of AP-POSS and MXene makes the resultant PS nanocomposites exhibit significantly improved thermal and thermoxidative stability, e.g. 22 °C and 39 °C increases in the temperature at 5 wt% mass loss under nitrogen and air, respectively. Meanwhile, a 39.1 % reduction in the peak heat release rate, a respective 54.4 % and 35.6 % reduction in the peak CO production rate and the peak CO2 production rate was achieved, which are superior to those of its own and previous counterparts. This outstanding fire safety is attributed to the combination of adsorption, catalytic and barrier effects of POSS-Ti3C2Tx. Hence, as-designed functionalized MXenes can be effectively applied in PS to formulate multifunctional polymer nanocomposites attractive for wide potential applications.

Interface decoration of exfoliated MXene ultra-thin nanosheets for fire and smoke suppressions of thermoplastic polyurethane elastomer.

Thermoplastic polyurethane (TPU) has broad applications as lightweight materials due to its multiple advantages and unique properties. Nevertheless, toxicity emission under fire conditions remains a major concern, particularly in building fire scenarios. To circumvent the problem, it is imperative that an effective flame retardant is sought to suppress the flame and release of combustion/smoke products whilst maintaining the favorable material properties of TPU. In the current work, a simple method is proposed for the preparation and utilization of cetyltrimethyl ammonium bromide (CTAB) and tetrabutyl phosphine chloride (TBPC) modified Ti3C2 (MXene) ultra-thin nanosheets. During the cone calorimeter tests, significant reduction in peak heat release rate (51.2% and 52.2%), peak smoke production rate (57.1% and 57.4%), peak CO production (39.4% and 41.6%) and peak CO2 production (49.7% and 51.7%) were recorded by the mere introduction of 2 wt.% CTAB-Ti3C2 and TBPC-Ti3C2 to TPU. These superior fire safety properties resulting from the significant reduction of the fire, smoke and toxicity hazards are attributed to the excellent dispersion, catalytic and barrier effect of Ti3C2 ultra-thin nanosheets in TPU. Future applications of exfoliated MXene nanosheets as flame retardant appear to be very promising.

[Association of Ureaplasma urealyticum with the types of antisperm antibody in infertile men].

OBJECTIVE: To investigate the prevalence of Ureaplasma urealyticum (UU) infection in infertile men, its influence on routine semen parameters and the distribution of antisperm antibody (AsAb) and its types in infertile patients with UU infection. METHODS: We detected the positive rate of UU infection, semen parameters, and the distribution of AsAb and its types in 662 infertile men and 25 normal fertile male controls followed by comparison of the obtained data between the two groups of subjects. RESULTS: The positive rate of UU infection was significantly higher in the infertile men than in the normal controls (52.87% ï¼»350/662ï¼½ vs 16.00% ï¼»4/25ï¼½, χ2 = 11.68, P <0.05). The semen volume, sperm count, sperm concentration and percentage of progressively motile sperm were remarkably lower in the UU-positive infertile males than in the control group (P <0.05). No statistically significant difference was observed between the UU-positive and UU-negative groups in the positive rates of total AsAb (43.4% vs 36.5%, χ2 = 3.25, P >0.05) and AsAb IgA, IgM and IgG in the seminal plasma, or in the percentages of serum AsAb IgM (16.9% vs 20.5%, χ2 = 1.22, P >0.05) and IgG (32.7% vs 28.9%, χ2 = 0.99, P >0.05) except in that of serum AsAb IgA (23.6% vs 17.0%, χ2 = 4.03, P <0.05). CONCLUSIONS: The UU infection rate is high in infertile males, which decreases the semen volume, total sperm count, motile sperm concentration and percentage of progressively motile sperm and increases the positive rate of serum AsAb IgA.

Properties of an alginate-degrading Flavobacterium sp. strain LXA isolated from rotting algae from coastal China.

A novel bacterium exhibiting alginolytic activity was isolated from rotten algae. The alginate-degrading activity was detected in the culture supernatant by measuring the decrease in alginate viscosity or the increase in reducing sugars. Basic characterization showed that it was gram negative, rod shaped, yellow pigmented, and positive for oxidase and catalase, with a DNA G+C content of 35.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that this strain is related to members of the genus Flavobacterium. Sequence similarity values with their nearest phylogenetic neighbours ranged from 95.9% to 96.7%. Genotypic results, together with phenotypic characteristics, differentiated this species from related Flavobacterium organisms with validly published names, which suggests that the organism should be a new species of the genus Flavobacterium tentatively named as Flavobacterium sp. strain LXA.

[Manganeseporphyrin/vanadium-substituted polyoxometalate new coordination compound: synthesis, characterization and catalytic activity].

A new kind of manganeseporphyrin/vanadium-substituted polyoxometalate coordination compound was synthesized by meso-tetrakis(4-trimethylamidiophenyl) manganeseporphyrin and vanadium-substituted polyoxometalate H5 PMo10 V2O4 reacting in water solution at room temperature, and its structures were studied by IR spectrometry and UV-Vis spectrometry. The results show that metalloporphyrin ring structure and polyoxometalate cage structure still exist in the coordination compound, and these two parts connect with each other by chemical bond. As an excellent catalyst, its effects on benzene hydroxylation and catalytic capabilities were studied with H2O2 solution as an oxidant under mild reaction condition, meanwhile the catalytic active centre in the benzene hydroxylation reaction was discussed. The results indicated that V atom in polyoxometalate is the main centre of catalytic activity, while the presence of manganeseporphyrin could improve its catalytic activity greatly.

[New iron-porphyrin/vanadium-substituted polyoxometalate catalyst: synthesis, characterization and catalytic activity].

A new kind of iron-porphyrin/vanadium-substituted polyoxometalate coordination compound was synthesized by the ion exchange reaction of FeTTMAPPI and H5PMo10V2o40 in solution. The new catalyst was characterized by IR spectrometry and UV-Vis spectrometry. As an excellent catalyst, its effects on benzene hydroxylation and catalytic capabilities were studied with H2O2 solution as the oxidant. The results indicated that the products contained the conjugated structure of porphyrin and the cage structure of polyoxometalate, the V atom in polyoxometalate is the main centre of catalytic activity, meanwhile the presence of iron-porphyrin could increase its catalytic activity greatly.