Although many techniques are available to assess enamel erosion in vitro, a simple, non-destructive method with sufficient sensitivity for quantifying dental erosion is required. This study characterized the bovine de...Although many techniques are available to assess enamel erosion in vitro, a simple, non-destructive method with sufficient sensitivity for quantifying dental erosion is required. This study characterized the bovine dental enamel erosion induced by various acidic beverages in vitro using attenuated total reflection Fourier transform infrared （ATR-FTIR） spectroscopy. Deionized water （control） and 10 acidic beverages were selected to study erosion, and the pH and neutralizable acidity were measured. Bovine anterior teeth （110） were polished with up to 1 200-grit silicon carbide paper to produce flat enamel surfaces, which were then immersed in 20 mL of the beverages for 30 min at 37 ℃. The degree of erosion was evaluated using ATR-FTIR spectroscopy and Vickers＇ microhardness measurements. The spectra obtained were interpreted in two ways that focused on the ~1, ~3 phosphate contour： the ratio of the height amplitude of ~3 P04 to that of/11 P04 （Method 1） and the shift of the v3 P04 peak to a higher wavenumber （Method 2）. The percentage changes in microhardness after the erosion treatments were primarily affected by the pH of the immersion media. Regression analyses revealed highly significant correlations between the surface hardness change and the degree of erosion, as detected by ATR-FTIR spectroscopy （P〈0.001）. Method 1 was the most sensitive to these changes, followed by surface hardness change measurements and Method 2. This study suggests that ATR- FTIR spectroscopy is potentially advantageous over the microhardness test as a simple, non-destructive, sensitive technique for the quantification of enamel erosion.展开更多
The development of sustainable,eco-friendly polyesters from renewable resources is crucial for reducing dependence on petroleum-based plastics.However,despite advances in microbial pro-duction of bioplastics,significa...The development of sustainable,eco-friendly polyesters from renewable resources is crucial for reducing dependence on petroleum-based plastics.However,despite advances in microbial pro-duction of bioplastics,significant challenges remain in achieving high conversion efficiency and scalability for industrial applications.This study is the first to report the synthesis of a 100%bio-based polyester using both 1,12-dodecanedioic acid(1,12-diacid)and 1,12-dodecanediol(1,12-diol)via a two-step microbial bioconversion from a single plant oil-derived alkane.An engineered Candida tropicalis strain produced 150 g/L of 1,12-diacid with a productivity of 1.53 g/(L·h)in a 5 L fed-batch system using a two-phase biotransformation strategy.Escherichia coli engineered to express carboxylic acid reductase,which reduces carboxylic acids to aldehydes,and its ac-tivation enzyme phosphopantetheinyl transferase,converted 1,12-diacid into 68 g/L 1,12-diol with a productivity of 1.42 g/(L·h)in a 5 L fed-batch system,representing high titer and pro-ductivity for microbial production of long-chainα,ω-diols.Both monomer production processes were successfully scaled up to a 50 L pilot fermenter,validating their potential for industrial implementation.A highly efficient downstream purification process was developed,achieving>98%purity and recovery rates for both monomers.The bio-derived monomers enabled the syn-thesis of polyesters with molecular weight and thermal characteristics similar to petroleum-based monomers of the same chemical structure.This integrated approach establishes a robust and scal-able microbial platform that converts renewable lipid feedstocks into fully bio-based polyesters,thereby demonstrating an environmentally sustainable and industrially viable route to circular bioeconomy-based polyester production.展开更多
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)the Ministry of Education(2013R1A1A2061732)
文摘Although many techniques are available to assess enamel erosion in vitro, a simple, non-destructive method with sufficient sensitivity for quantifying dental erosion is required. This study characterized the bovine dental enamel erosion induced by various acidic beverages in vitro using attenuated total reflection Fourier transform infrared （ATR-FTIR） spectroscopy. Deionized water （control） and 10 acidic beverages were selected to study erosion, and the pH and neutralizable acidity were measured. Bovine anterior teeth （110） were polished with up to 1 200-grit silicon carbide paper to produce flat enamel surfaces, which were then immersed in 20 mL of the beverages for 30 min at 37 ℃. The degree of erosion was evaluated using ATR-FTIR spectroscopy and Vickers＇ microhardness measurements. The spectra obtained were interpreted in two ways that focused on the ~1, ~3 phosphate contour： the ratio of the height amplitude of ~3 P04 to that of/11 P04 （Method 1） and the shift of the v3 P04 peak to a higher wavenumber （Method 2）. The percentage changes in microhardness after the erosion treatments were primarily affected by the pH of the immersion media. Regression analyses revealed highly significant correlations between the surface hardness change and the degree of erosion, as detected by ATR-FTIR spectroscopy （P〈0.001）. Method 1 was the most sensitive to these changes, followed by surface hardness change measurements and Method 2. This study suggests that ATR- FTIR spectroscopy is potentially advantageous over the microhardness test as a simple, non-destructive, sensitive technique for the quantification of enamel erosion.
基金supported by the KEIT R&D Program(No.20025698&00432188)funded by the Ministry of Trade,Industry&Energy(Republic of Korea).
文摘The development of sustainable,eco-friendly polyesters from renewable resources is crucial for reducing dependence on petroleum-based plastics.However,despite advances in microbial pro-duction of bioplastics,significant challenges remain in achieving high conversion efficiency and scalability for industrial applications.This study is the first to report the synthesis of a 100%bio-based polyester using both 1,12-dodecanedioic acid(1,12-diacid)and 1,12-dodecanediol(1,12-diol)via a two-step microbial bioconversion from a single plant oil-derived alkane.An engineered Candida tropicalis strain produced 150 g/L of 1,12-diacid with a productivity of 1.53 g/(L·h)in a 5 L fed-batch system using a two-phase biotransformation strategy.Escherichia coli engineered to express carboxylic acid reductase,which reduces carboxylic acids to aldehydes,and its ac-tivation enzyme phosphopantetheinyl transferase,converted 1,12-diacid into 68 g/L 1,12-diol with a productivity of 1.42 g/(L·h)in a 5 L fed-batch system,representing high titer and pro-ductivity for microbial production of long-chainα,ω-diols.Both monomer production processes were successfully scaled up to a 50 L pilot fermenter,validating their potential for industrial implementation.A highly efficient downstream purification process was developed,achieving>98%purity and recovery rates for both monomers.The bio-derived monomers enabled the syn-thesis of polyesters with molecular weight and thermal characteristics similar to petroleum-based monomers of the same chemical structure.This integrated approach establishes a robust and scal-able microbial platform that converts renewable lipid feedstocks into fully bio-based polyesters,thereby demonstrating an environmentally sustainable and industrially viable route to circular bioeconomy-based polyester production.
