1. A fluorescence endoscope apparatus comprising:
an illuminating portion that radiates excitation light and illumination light onto an imaging subject;
a fluorescence imaging portion that acquires a fluorescence image by capturing fluorescence emitted at the imaging subject due to the irradiation with the excitation light from the illuminating portion;
a storage portion that stores the fluorescence image acquired by the fluorescence imaging portion;
a return-light imaging portion that acquires a return-light image by capturing return light returning from the imaging subject due to the irradiation with the illumination light from the illuminating portion;
an image-information extracting portion that extracts, from the return-light image acquired by the return-light imaging portion, image information that expresses the intensity of the illumination light radiated onto the imaging subject;
a number-of-integrated-images setting portion that sets a number of integrated images so that the number is decreased with an increase in the intensity of the illumination light, based on the image information extracted by the image-information extracting portion; and
an average-image generating portion that generates an average image by averaging the fluorescence images, stored in the storage portion, in a number corresponding to the number of integrated images set by the number-of-integrated-images setting portion.
2. A fluorescence endoscope apparatus according to claim 1, wherein the image-information extracting portion extracts the image information in the form of an average gradation value for a plurality of pixels in the return-light image.
3. A fluorescence endoscope apparatus according to claim 1, wherein the image-information extracting portion extracts the image information in the form of a total contour length that represents locations where gradation values of adjacent pixels in the return-light image change by an amount exceeding a predetermined threshold.
4. A fluorescence endoscope apparatus according to claim 1, wherein the image-information extracting portion extracts the image information in the form of a gradation-value distribution along a straight line that horizontally runs across the return-light image.
5. A fluorescence endoscope apparatus according to claim 1, wherein the image-information extracting portion extracts the image information by averaging gradation-value distributions along a plurality of straight lines that horizontally run across the return-light image.
6. A fluorescence endoscope apparatus according to claim 1, further comprising:
an amount-of-change calculating portion that calculates an amount of change between a first fluorescence image acquired by the fluorescence imaging portion and a second fluorescence image acquired before the first fluorescence image,
wherein the storage portion stores the first fluorescence image by multiplying the image by a weight coefficient that is increased with a decrease in the amount of change calculated by the amount-of-change calculating portion.
7. A fluorescence endoscope apparatus according to claim 6, wherein the amount-of-change calculating portion calculates the amount of change in the form of a summed total of gradation values of a subtracted image between the first fluorescence image and the second fluorescence image.
8. A fluorescence endoscope apparatus according to claim 6, wherein the amount-of-change calculating portion calculates the amount of change in the form of a difference between a total contour length of the first fluorescence image and a total contour length of the second fluorescence image.
9. A fluorescence endoscope apparatus according to claim 6, wherein the amount-of-change calculating portion calculates the amount of change in the form of a difference between the contour of the first fluorescence image and the contour of the second fluorescence image, when the summed total of the gradation values of the subtracted image between the first fluorescence image and the second fluorescence image is equal to or below a threshold.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for preparing 4,4,4-trifluorobutane-2-one, comprising:
providing a fluorobutene selected from the group consisting of 2,4,4,4-tetrafluoro-1-butene, (E)-1,1,1,3-tetrafluoro-2-butene, (Z)-1,1,1,3-tetrafluoro-2-butene, and a mixture thereof; and
reacting the fluorobutene with a proton acid and water to form 4,4,4-trifluorobutane-2-one.
2. A method according to claim 1, wherein the proton acid is selected from the group consisting of sulfuric acid, fuming sulfuric acid, hydrogen chloride, hydrogen bromide, hydrogen iodide, nitric acid, alkanesulfonic acids having a carbon number of 1 to 6; partially fluorinated alkanesulfonic acids represented by CnHaF2n+1\u2212aSO3H, where \u201cn\u201d represents an integer of 1 to 6, and \u201ca\u201d represents an integer of 1 or more but 2n or less; perfluoroalkane sulfonic acids having a carbon number of 1 to 6; anhydrides of the alkanesulfonic acids, the partially fluorinated alkanesulfonic acids, and the perfluoroalkanesulfonic acids.
3. A method according to claim 1, wherein the proton acid is a concentrated sulfuric acid having a concentration of 95 wt % or more.
4. A method according to claim 1, wherein the proton acid is in a state of an aqueous solution.
5. A method according to claim 1, wherein the proton acid is added at an amount of 0.5 to 10 moles, and water is added at an amount of 0.8 to 10 moles, per a mole of the fluorobutene.
6. A method according to claim 1, wherein the fluorobutane is prepared by subjecting 1,1,1,3,3-pentafluorobutane to a dehydrofluorination process.
7. A method according to claim 6, wherein the dehydrofluorination process is carried out by thermolysis of 1,1,1,3,3-pentafluorobutane at a temperature of 200\xb0 C. to 700\xb0 C.
8. A method according to claim 6, wherein the dehydrofluorination process is carried out by heating 1,1,1,3,3-pentafluorobutane at a temperature of 0\xb0 C. to 300\xb0 C., in the presence of a base.
9. A method according to claim 8, wherein the base is selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, alkali earth metal hydroxides, and organic bases.
10. A method according to claim 6, wherein the dehydrofluorination process is carried out by heating 1,1,1,3,3-pentafluorobutane in the presence of a catalyst.
11. A method according to claim 10, wherein the catalyst is selected from the group consisting of an activated carbon, a chromium catalyst carried on an activated carbon (CrC), and a titanium catalyst carried on an activated carbon (TiC).
12. A method according to claim 6, wherein after the dehydrofluorination process, the crude mixture of fluorobutenes obtained is reacted with the proton acid and water without purification.
13. A method for preparing 4,4,4-trifluorobutane-2-one, comprising:
providing a fluorobutene selected from the group consisting of 2,4,4,4-tetrafluoro-1-butene, (E)-1,1,1,3-tetrafluoro-2-butene, (Z)-1,1,1,3-tetrafluoro-2-butene, and a mixture thereof;
first reacting the fluorobutene(s) with a proton acid; and
second adding water therein to form 4,4,4-trifluorobutane-2-one.
14. A method according to claim 13, wherein the proton acid is selected from the group consisting of sulfuric acid, fuming sulfuric acid, hydrogen chloride, hydrogen bromide, hydrogen iodide, nitric acid, alkanesulfonic acids having a carbon number of 1 to 6; partially fluorinated alkanesulfonic acids represented by CnHaF2n+1\u2212aSO3H, where \u201cn\u201d represents an in of 1 to 6, and \u201ca\u201d represents an integer of 1 or more but 2n or less; perfluoro alkanesulfonic acids having a carbon number of 1 to 6; anhydrides of the alkanesulfonic acids, the partially fluorinated alkanesulfonic acids, and the perfluoroalkanesulfonic acids.
15. A method according to claim 13, wherein the proton acid is a concentrated sulfuric acid having a concentration of 95 wt % or more.
16. A method according to claim 13, wherein the proton acid is in a state of an aqueous solution, and wherein the aqueous solution includes water at a molar number less than that of the fluorobutene, and then, water is supplemented such that a total molar number of water included in a reaction vessel exceeds a molar number of the fluorobutene.
17. A method according to claim 13, wherein the proton acid is added at an amount of 0.5 to 10 moles, and water is added at an amount of 0.8 to 10 moles, per a mole of the fluorobutene.