緑茶中のビタミンB12濃度に与えるアスコルビン酸の影響

急須を用いて乾燥茶葉から抽出された緑茶抽出液中のビタミンB_濃度は849±35pg/100ml,缶入りおよびペットボトル入り緑茶飲料5種の平均濃度は280±45pg/100mlであり,急須で入れた場合の方が3倍高い結果となった。ビタミンB_が後者で低かった理由として製造工程中にアスコルビン酸が添加されたためである可能性が考えられる。アスコルビン酸はビタミンB_と共存する場合にビタミンB_を分解することが既に報告されている。そこでアスコルビン酸を測定したところ,急須による緑茶抽出液5.87±0.66m/100ml,缶入りおよびペットボトル入り緑茶飲料5種の平均濃度は35.22±8.27mg/100mlであり,後者が前者の6倍の値であった。アスコルビン酸の添加によってビタミンB_濃度が影響を受けるのかを検討するために,急須を用いた抽出の際にアスコルビン酸を添加し,ビタミンB_濃度への影響を確認した。しかし,その影響は,緑茶抽出液のビタミンB_濃度の7%の減少に留まっていた(緑茶飲料では67%減少していた)。さらにアスコルビン酸添加後の加圧加熱(120℃)の影響も調べたが,影響は見られなかった。これらの結果から,極めて微量ながらも緑茶からビタミンB_が摂取できる可能性が示され,それは緑茶飲料より急須で乾燥茶葉から抽出した場合の方がより効率がよいことが示された。The vitamin B_ concentration in the green tea extract poured out from the teapot was measured to be 849±35 pg/100ml. The average concentration of 5 different green tea beverages from the markets was 280±45 pg/100ml. The lower content of vitamin B_ in the tea beverages may be due to the supplemented ascorbic acid added in the process of manufacture since the content of vitamin B_ in the solution was reported to decrease in coexistence with ascorbic acid. In fact the concentration of ascorbic acid in the tea beverages, 35.22±8.27mg/100ml in average, was six times higher than that of the poured tea, 5.87±0.66mg/100ml. Then we examined the effect of ascorbic acid added during the tea extraction on the vitamin B_ concentration. However, the addition of ascorbic acid at the same concentration of the tea beverages decreased only 7% of the vitamin B_ concentration in the poured tea compared to 67% decrease observed in the tea beverages. Moreover, the effect of heating at 120°C under pressure after the addition of ascorbic acid was examined and no difference was observed by heating. The result indicated that the green tea poured out from the teapot, though in a small quantity, was a better source for vitamin B_ than the tea beverages on markets

DIDACTICAL N-2 LASERS

This work presents the design, construction and parameterization of Nitrogen lasers, which are easy to build by undergraduate students. These are transversal discharge lasers at atmospheric pressure (TEA), excited by a Blumlein circuit, emitting nanosecond pulses in the ultraviolet region of the spectrum (lambda = 337.1 nm). Didactical applications of these low cost lasers are discussed

Filtergraph calibration for the Polarimetric and Heliosismic Imager

International audienc

Filtergraph calibration for the Polarimetric and Heliosismic Imager

International audienc

Filtergraph calibration for the Polarimetric and Heliosismic Imager

International audienc

Hubble constant and nuclear equation of state from kilonova spectro-photometric light curves

The merger of two compact objects of which at least one is a neutron star is signalled by transient electromagnetic emission in a kilonova (KN). This event is accompanied by gravitational waves and possibly other radiation messengers such as neutrinos or cosmic rays. The electromagnetic emission arises from the radioactive decay of heavy r-process elements synthesized in the material ejected during and after the merger. In this paper we show that the analysis of KNe light curves can provide cosmological distance measurements and constrain the properties of the ejecta. In this respect, MAAT, the new Integral Field Unit in the OSIRIS spectrograph on the 10.4 m Gran Telescopio CANARIAS (GTC), is well suited for the study of KNe by performing absolute spectro-photometry over the entire 3600 − 10 000 Å spectral range. Here, we study the most representative cases regarding the scientific interest of KNe from binary neutron stars, and we evaluate the observational prospects and performance of MAAT on the GTC to do the following: (a) study the impact of the equation of state on the KN light curve, and determine to what extent bounds on neutron star (NS) radii or compactness deriving from KN peak magnitudes can be identified and (b) measure the Hubble constant, H0, with precision improved by up to 40%, when both gravitational wave data and photometric-light curves are used. In this context we discuss how the equation of state, the viewing angle, and the distance affect the precision and estimated value of H0

Hubble constant and nuclear equation of state from kilonova spectro-photometric light curves

The merger of two compact objects of which at least one is a neutron star is signalled by transient electromagnetic emission in a kilonova (KN). This event is accompanied by gravitational waves and possibly other radiation messengers such as neutrinos or cosmic rays. The electromagnetic emission arises from the radioactive decay of heavy r-process elements synthesized in the material ejected during and after the merger. In this paper we show that the analysis of KNe light curves can provide cosmological distance measurements and constrain the properties of the ejecta. In this respect, MAAT, the new Integral Field Unit in the OSIRIS spectrograph on the 10.4 m Gran Telescopio CANARIAS (GTC), is well suited for the study of KNe by performing absolute spectro-photometry over the entire 3600-10 000 spectral range. Here, we study the most representative cases regarding the scientific interest of KNe from binary neutron stars, and we evaluate the observational prospects and performance of MAAT on the GTC to do the following: (a) study the impact of the equation of state on the KN light curve, and determine to what extent bounds on neutron star (NS) radii or compactness deriving from KN peak magnitudes can be identified and (b) measure the Hubble constant, H0, with precision improved by up to 40%, when both gravitational wave data and photometric-light curves are used. In this context we discuss how the equation of state, the viewing angle, and the distance affect the precision and estimated value of H0