A fluorescent switch for sequentially and selectively sensing copper(II) and L-histidine in vitro and in living cells

National Natural Science Foundation of China [21175122, 91127036, 21375121]; Fundamental Research Funds for Central Universities [WK2060190018]Herein, we report the development of a new fluorescent switch for sequential and selective sensing of Cu2+ and L-histidine (L-His) in vitro and in living cells for the first time. In the absence of metal ions, Ac-SAACQ- Gly-Gly-Gly-Lys (FITC) (1) exhibits comparable fluorescence to that of free FITC. In the presence of metal ions, 1 selectively coordinates to Cu2+, causing its fluorescence emission to be quenched via photoinduced electron transfer. Interestingly, the as-formed 1-Cu2+ complex selectively responds to L-His among the 20 natural amino acids by turning its fluorescence on. This property of fluorescence switch of 1 was successfully applied for qualitatively and quantitatively sensing Cu2+ and L-His in vitro. Using this dual functional probe, we also sequentially imaged Cu2+ and L-His in living HepG2 cells. Our new probe 1 could be applied for not only environmental monitoring but also biomolecule detection in the near future

Optimized Pretreatment of Kenaf (Hibiscus cannabinus) Phloem Insulation Cotton

Using response surface methodology, the pretreatment conditions of kenaf fibers were optimized to improve the tensile strength of kenaf phloem insulation cotton (KPIC). The effects and interactions of three parameters—sodium hydrate concentration (X1), soaking time (X2), and beating time (X3)—on the tensile strength of the kenaf fibers were investigated. The chemical structure of the specimens was characterized by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). Sodium hydrate concentration had the greatest effect on kenaf fibers. The maximum tensile strength of 117.6 N resulted from a sodium hydrate concentration of 4%, soaking time of 50 h, and beating time of 12 min. As shown by FTIR and XRD, optimized pretreatment generated surface functional groups and increased the tensile strength of fibers. In conclusion, the pretreatment of kenaf fiber significantly improves the tensile strength of KPIC and also improves the retention rate of the chemicals used during the preparation of KPIC.Validerad; 2016; Nivå 2; 20151110 (aliwan)</p

Effect of Boron-Zinc-Aluminum-Silicium Compounds on the Fire Performance of Ultra-Low Density Fiberboards (ULDFs)

B-Zn-Si-Al compounds, as a modification of Si-Al compounds, is made of sodium silicate, zinc sulfate, borax and aluminum sulfate, acting as a fire retardant during the preparation of ultra-low density fiberboards (ULDFs). An orthogonal experiment was used to optimize the amount of the four compounds, according to the results of limiting oxygen index. Fourier transform infrared spectra was employed to preliminarily make sure chemical structure of the compounds. Cone calorimeter was used measure fire performance of ULDFs. The results suggested that the optimized sodium silicate solution, aluminum sulfate solution, zinc sulfate and borax were 27.0 mL, 27.0 mL, 3.0 g and 6.5 g, respectively, corresponding to oxygen index of 29.5%. Al-O-B and Si-O-Zn bonds were detected at 1397, 796 cm-1 and 867 cm-1, respectively. The heat release rate, total heat release, and total smoke release obviously decreased and mass residual ratio increased. Conclusively, B-Zn-Si-Al compounds effectively protect fibers from fire hazard

Evaluating the Effectiveness of Complex Fire-Retardants on the Fire Properties of Ultra-low Density Fiberboard (ULDF)

The preparation conditions of complex fire-retardant (FR) agents containing boron compounds (BF, X1), nitrogen-phosphorus compounds (NPF, X2), silicon compounds (SF, X3), and halogen compounds (HF, X4) for ultra-low density fiberboard (ULDF) were optimized using a response surface methodology. The effects and interactions of X1, X2, X3, and X4 on the fire properties of ULDF were investigated. An optimum char yield of 61.4% was obtained when the complex fire-retardant agents contained 33.9% boron, 27.2% nitrogen-phosphorus, 15.0% silicon, and 28.6% halogen. Compared with control fiberboard (CF), the heat release rate (HRR) profiles of all fiberboards with FRs were reduced. The peak HRR reduction in BF and NPF was more pronounced than for SF and HF at this stage. And the mixed fiberboard (MF) had the lowest pkHRR of 75.02 kW m−2. In total heat release (THR) profiles, all fiberboards with FRs were lower than the CF. Unlike the HRR profiles, HF had the lowest THR profile of 15.33 MJ/m−2. Additionally, Si compounds showed greater effectiveness in preventing ULDF mass loss than BF, NPF, and HF. MF showed the highest residual mass (40.94%). Furthermore, the synergistic effect between four FR agents showed more significant results in ULDFs.Validerad; 2016; Nivå 2; 20151022 (aliwan)</p

Optimization of Aluminum/Silicon Compounds on Fire Resistance of Old Corrugated Container Fiber Foam Material

Old corrugated container fiber foam material (OCCM) was prepared using a liquid frothing approach. The effect of the content of Al/Si compounds, the molar ratio of Al3+/SiO2, and different addition form on the limited oxygen index (LOI) and residue percentage of OCCM was optimized using an orthogonal design. The fire resistance of OCCM was best when the content of Al/Si compounds was 900 mL, the molar ratio of Al3+/SiO2 was 1:1, and the aluminum sulfate solution was added first, followed by the separately added sodium silicate solution. Under these conditions, the LOI and residue percentage of OCCM reached 32.3 and 53.51%, respectively. Thermogravimetric analysis indicated that Al/Si compounds promoted char formation and reduced the heat release of the optimized OCCMs during depolymerisation. Compared with the control group, the residue percentage of optimized OCCM was increased from 12.49% to 37.98%. Fourier transform infrared spectroscopy identified the functional groups of Al/Si compounds in the optimized OCCMs, confirming that pyrolysis of the optimized OCCMs was affected by Al/Si compounds

Effect of PVDC on the Fire Performance of Ultra-Low Density Fiberboards (ULDFs)

Poly vinylidene chloride-vinyl chloride emulsions (PVDC) were added as a substitute for chlorinated paraffin (CP) in the preparation of ultra-low density fiberboards (ULDFs). The micromorphology and fire performance of ULDFs were investigated using a scanning electron microscope, limiting oxygen index instrument, and cone calorimeter. The results showed that PVDC specimens were coated with a regularly smooth film, while the distribution of CP inside CP specimens was uneven. The limiting oxygen index increased with the dosage of PVDC, then reached a plateau at 50 mL and 28%, slightly higher than CP specimens (27.3%). The peak of heat release rate, mean heat release rate, mean CO, and total smoke release of PVDC specimens was reduced 43.3%, 13.5%, 38.5%, and 51.5% lower than respective CP specimens, and with nearly the same total heat release (only 0.04 MJ/m2 higher). Thus, PVDC exhibited excellent heat-reducing and smoke-suppressing properties and could replace CP in ULDFs

PROPERTIES OF NbTi50 SUPERCONDUCTING COMPOSITE WIRE

Dans cet article sont présentées les mesures du courant critique à 4,2K sur des fils multifilamentaires de Nb Ti (50 % en poids) à des champs jusqu'à HC2. Les mesures indiquent que les meilleurs échantillons ont d'excellentes propriétés de courant critique en particulier à champ moyen. Le courant critique à 4,2K est par exemple de 3460 A/ mm2 à 5T, et de 1020 A/ mm2 à 8T. Le rôle crucial joué par des traitements thermiques multiples dans l'obtention de hautes valeurs du courant critique pour des alliages de Nb Ti (50 %) est discuté. La force de pinning et les aspects de microstructure sont discutés.The results of critical current measurements of NbTi50 multifilamentary wire at 4.2 K in the fields up to Hc2 are reported in this paper. The measurements show that the best optimized samples have excellent critical current properties, especially in mid-field. Its Jc 4.2K), for instance, is 3460 A/mm2 at 5 T, and 1020 A/mm2 at 8 T. The crucial role played by multiple heat treatments in developing high Jc values in NbTi50 alloy are described. The flux pinning force and microstructural features are discussed

Treatment effect on the adsorption capacity of alumina for removal fluoride

Acid and base treated alumina particles were studied to assess their capacities for the adsorption of fluoride from aqueous solutions. The surface morphology of untreated alumina was analyzed by SEM and its crystal structure was checked by XRD, and was analyzed by FTIR, SEM and EDS mapping after fluoride adsorption. SEM and EDS were also used to understand the surface change of the alumina after acid and base treatment. Fluoride adsorptions at two different initial fluoride concentrations were investigated. The results show that the fluoride adsorption mainly superficially happened on the alumina particle surface. SEM images show base treatment caused the alumina particle recrystallize, while acid treatment made the alumina particle more amorphous. The adsorption capacity of acid treated alumina was about twice compared with that of alumina, while the capacity of base treated alumina was only about half of that of alumina at the solution pH=7. The high adsorption capacity of acid treated alumina makes it suitable for potential application in fluoride removal from water

Effect of Boron-Zinc-Aluminum-Silicium Compounds on the Fire Performance of Ultra-Low Density Fiberboards

B-Zn-Si-Al compounds are modified Si-Al compounds made of sodium silicate, zinc sulfate, borax, and aluminum sulfate. They act as a fire retardant during the preparation of ultra-low density fiberboards (ULDFs). An orthogonal experiment was used to optimize the contents of the four compounds according to the limiting oxygen index. Fourier transform infrared spectroscopy was employed to preliminarily analyze the chemical structure of the compounds. Additionally, a cone calorimeter was used to assess the fire performance of the ULDFs. The results suggested that the optimized solution was made of 27.0 mL of sodium silicate solution, 27.0 mL of aluminum sulfate solution, 3.0 g of zinc sulfate, and 6.5 g of borax, resulting in an oxygen index of 29.5%. The bond Al-O-B was detected at 1397 and 796 cm-1. The Si-O-Zn bonds were detected at 867 cm-1. The heat release rate, total heat release, and total smoke release decreased and the mass residual ratio increased in the sample using the optimal conditions from the orthogonal array design. It was concluded that B-Zn- Si-Al compounds effectively protect fibers from fire.Validerad; 2016; Nivå 2; 20160331 (aliwan)</p