Changes of the Antarctic ozone hole : controlling mechanisms, seasonal predictability, and evolution

The ozone hole changes considerably from one year to the next. It varies between conditions in which springtime ozone is strongly depleted to others in which ozone is only weakly depleted. Those changes are shown to closely track anomalous planetary wave forcing of the residual circulation. The strong coherence with planetary wave forcing is consistent with similar coherence of springtime temperature, which modulates Polar Stratospheric Cloud (PSC). By controlling the lifetime of PSC, anomalous wave forcing determines the net activation of chlorine and bromine and, hence, springtime depletion of ozone during individual years. The strong coherence with planetary wave forcing affords long-range predictability. It supports a seasonal forecast of springtime depletion, which, through the ozone mass deficit, perturbs ozone across much of the Southern Hemisphere during subsequent months of summer. Conditioned upon wintertime wave structure, a hindcast of springtime depletion faithfully predicts the anomalous ozone observed. A reliable forecast of tropospheric planetary waves would thus enable springtime depletion to be predicted. The current evolution of Antarctic ozone is dominated by dynamically-induced changes. Representing its climate variability, those large changes obscure the more gradual evolution of springtime depletion, like that associated with the decline of chlorine. The strong dependence on planetary wave forcing, however, enables dynamically-induced changes of ozone to be identified accurately. Removing them unmasks the secular variation of Antarctic ozone, the part coherent over a decade and longer. Independent of dynamically-induced changes, that component discriminates to changes associated with stratospheric composition. It reveals a gradual but systematic rebound over the last decade. The upward trend is shown to be robust, significant at the 99.5% level. Uncertainty in this trend is thus small enough to make the probability of it arising through chance alignment of error less than 0.5%. The discriminated component mirrors the decline of effective stratospheric chlorine, representing a gradual return of springtime ozone toward its level in 1980 of 10-15%. It enables Antarctic ozone to be tracked relative to changes of chlorine, CO₂, and other features of climate more reliably than is otherwise possible.11 page(s

Obtaining Betulin Diacetate from the Outer Birch Bark and Studying it’s Antioxidant Activity

Предложен способ получения диацетата бетулина из бересты коры березы, совмещающий стадии экстракции бетулина из бересты уксусной кислотой и его этерификации. Способ не требует предварительного выделения бетулина и использования катализаторов этерификации. Структура диацетата бетулина подтверждена с помощью хромато-масс-спектрометрии, FTIR и ЯМР-спектроскопии. Изучена антиоксидантная активность полученного диацетата бетулина в экспериментах in vitro и in vivo.The new method of betulin diacetate obtaining from the outer birch bark was suggested. This method combines stages of the betulin extraction from the bark by acetic acid and it’s following eterification. The advanced method don’t require preview of getting betulin and use of eterification catalysts. Antioxidantion activity of betulin diacetate has been studed in the experiments in vivo and in vitro

Obtaining Betulin Diacetate from the Outer Birch Bark and Studying it’s Antioxidant Activity

Предложен способ получения диацетата бетулина из бересты коры березы, совмещающий стадии экстракции бетулина из бересты уксусной кислотой и его этерификации. Способ не требует предварительного выделения бетулина и использования катализаторов этерификации. Структура диацетата бетулина подтверждена с помощью хромато-масс-спектрометрии, FTIR и ЯМР-спектроскопии. Изучена антиоксидантная активность полученного диацетата бетулина в экспериментах in vitro и in vivo.The new method of betulin diacetate obtaining from the outer birch bark was suggested. This method combines stages of the betulin extraction from the bark by acetic acid and it’s following eterification. The advanced method don’t require preview of getting betulin and use of eterification catalysts. Antioxidantion activity of betulin diacetate has been studed in the experiments in vivo and in vitro