ABSTRACT
The water-soluble 3-mercaptopropionic acid (MPA)-stabilized CdTe (MPA-CdTe) quantum dots (QDs) were synthesized by aqueous suspension.The study showed that the fluorescence quenching process of Cu2+ to MPA-CdTe QDs,whose largest emission peak was 599 nm,could be described well by the theory of fluorescence quenching in competitive absorption systems and its modification of Stern-Volmer equations.By fittings,the results showed a good polynomial relationship between the fluorescence intensity F0/F and the concentration of Cu2+,when the concentration was in the range of 2.28 × 10-6-18.24 × 10-6 mol/L and 4.8 × 10-7-12 × 10-7 mol/L,and two polynomial equations were respectively elucidated based on dynamic and static quenching in competitive-absorption systems:F0/F =7.999-2.470c +0.339 c2,F0/F =3.154-0.160 c +0.049 c2 and degree of fitting are 0.991 and 0.993,respectively.The detection limit was 1.326 × 10-7.
ABSTRACT
Tibetan Medicine (TM) has become important source of feature industry in several main Tibetan regions with its unique cultural and natural resources. This article argued that the researches on TM basic theories are weak;ecological environment for TM is fragile;safety evaluation ability is relatively insufficient;standardization system for researches on TM is needed; reasonable talent team supporting the development of TM industry is required;The combination of production, learning and research is not close;innovation ability is low;guiding principles for the evaluation of new TM do not exist. All of these are main factors that restrict the development of TM industry. Therefore, the main measures for the promotion of TM are:improve research level of TM theories;strengthen the protection of TM resources;promote national standard construction of TM;improve collaborative innovation ability of TM;enhance talent team construction;formulate appropriate policies and create good marketing environment.
ABSTRACT
Objective To compare differences and similarities of the content of trigonelline in Himalaica mirabilis of either wild or cultivated materials from different places. Methods An HPLC method was established to determine the content of trigonelline in Himalaica mirabilis. ZORBAX XDB-CN column (4.6 mm×250 mm, 5 μm) was used, with mobile phase of acetonitrile-0.03%acetic acid (85∶15), flow rate of 0.8 mL/min, detection wavelength of 265 nm, determination wavelength of 360 nm, and column temperature of 30 ℃. Results Regression calculation was made on peak area with the reference solution concentration, and then got the regression equation A=23.409C-26.398, r=0.999 8. Trigonelline showed good linear relation with peak area among the range of 2.004-200.400 μg/mL. The average recovery of trigonelline was 99.57%, RSD=1.11%. Conclusion There was no significant difference in the content of trigonelline of either wild or cultivated materials from different places. This study laid the foundation of application of the cultivated Himalaica mirabilis.
ABSTRACT
This study was aimed to establish the TLC identification method of Radix Mirab ilis himalaic a. The β-sitosterol and daucosterol were used as the reference substances. The single-factor test was used. A variety of factors which affected TLC were systematically investigated to filter out the best TLC conditions for identification of different batches of medicines. The results showed that the best TLC conditions were as follows: silica gel G plates, extraction solvent (methanol), reagent (5% sulfuric acid in ethanol), extraction method (ultrasonic extraction with methanol), ex-tracted time (30 min), the agent (petroleum ether-ethyl acetate-acetone (5:2:1)) and sample volume (6 μL). It was concluded that the method, which had high separation degree, was reproducible and simple. It can be used as the quality control of Radix Mirab ilis himalaic a.