[en] The article is devoted to the study of the ms-DLE of the plant ''Hibiscus Rosa sinensis'' under the influence of various doses of UV-B radiation. The analysis of these parameters of Ms-DLE showed that at 5, 10, 15 minutes of UV-B exposure to the leaves Hibiscus Rosa-sinensis, the amplitude of the induction maximum (Am) and the stationary level (East) decreases, there is a noticeable inhibition of electron transport by FS 2. The most sensitive to the action of UV-B radiation component of ms-DLE induction flash.

[en] In spite of their efficiency, the use of synthetic antioxidants such as tert-butyl hydroquinone (TBHQ) has been questioned because of their possible carcinogenic effects. The purpose of this study was to establish a mixture of natural antioxidants that provides the optimum oxidative stability for margarine. Antioxidant treatments included 10 various mixtures (F1- F10) containing 100-500 ppm tocopherol mixture (Toc), 100-200 ppm ascorbyl palmitate (AP), 100-200 ppm rosemary extract (Ros) and 1000 ppm lecithin(Lec) along with a control or F0 (with no antioxidant) and F11 containing 120 ppm TBHQ. The effect of antioxidant mixtures on the stability of margarine samples during an oven test (60 +-1 deg. C), rancimat test at 110 deg. C and storage at 4 deg. C was evaluated. The final ranking of the natural antioxidant mixtures was as follows: F2, F10>F5, F9>F8>F1, F3, F4>F6, F7. Considering the results of this research and ranking criteria, F2 (200 ppmAp + 200 ppmRos) and F10 (200 ppmRos + 200 ppm Toc + 1000 ppm Lec) were recommended as substitutes for TBHQ to maintain the quality and increase the shelf-life of margarine. (author)

[en] This response article aims to provide an overview of the literature highlighting experimental work that, in contrast to the account by Luque and Schmickler, evidences the non-adiabatic nature of the electron transfer process

[en] Methods for the preparation and various transformations of acetylenic derivatives of quinones, which are key intermediates in the synthesis of fused heterocyclic quinoid structures and some highly unsaturated compounds, are surveyed in detail.

[en] In this study, an efficient way by plasma induced mutation was applied to improve the hydroquinone degradation capacity of Serratia marcescens AB 90027 (SM27). The results showed that combined with the selection of hydroquinone tolerance, the mutant with high hydroquinone degradation ability induced by plasma could be achieved. The best dose for plasma mutation was 15 s, which showed a 47.0% higher positive mutation ratio. Besides, the aimed mutant was markedly different from the parent strain (SM27) in colonial traits while cultivated on Kings media. Finally, the hydroquinone degradation ratio reached 70.5% using the induced mutant strain with 1500 mg/L hydroquinone (HQ) after 15 days of cultivation as the selective conditions; however, it was only 46.7% for SM27. The improvement of the degradation capacity by the induced mutant with a high concentration of HQ selection was attributed to its faster growth and higher hydroquinone tolerance compared with that of the parent strain.

[en] Outer sphere electron transfer reactions on pure metal electrodes are often adiabatic and hence independent of the electrode material. Since it is not clear, whether adiabatic electron transfer can also occur on a semi-metal like graphite, we have re-investigated experimental data presented in a recent communication by Nissim et al. [Chemical Communications 48 (2012) 3294] on the reactions of quinones on graphite. We have supplemented their work by DFT calculations and conclude, that these reactions are indeed adiabatic. This contradicts the assertion of Nissim et al. that the rates are proportional to the density of states at the Fermi level

[en] A review of the molecular spectroscopy of naphto and anthraquinone (NQ, AQ), the hydroxy-derivatives and the divalent metal chelate complexes is presented. The assignment of the infrared and Raman spectra of NQ and AQ are essentially complete. In the hydroxy-derivatives the existence of one or more intramolecular unsymmetric hydrogen bonds is shown. The information on divalent metal chelate compounds of hydroxyquinones is very incomplete and contains a few data concerning their structures and metal-oxygen vibrations

[en] Color is a key quality trait of wheat-based products and polyphenol oxidase (PPO) is implicated to play a significant role in their undesirable darkening. Polyphenol oxidase catalyzes the oxidation of phenols to quinines, which auto oxidize and polymerize with amino acid of cellular proteins resulting brown and black pigmentation propounding reduced nutritional values. In present study, the PPO activity in 50 different Pakistani wheat cultivars was investigated and grouped into three categories viz; low, medium and high PPO activity cultivars. PPO is a heat labile enzyme. To investigate effect of heat stress, nine cultivars from each category were chosen for treatment at 30, 40 and 50 deg. C for 30, 60, and 120 minutes each. A substantial change was experienced in PPO activity as compared to room temperature. Two wheat cultivar Wafaq-2001 and AS-2002 showed a compromising attitude of minimum PPO activity at 30 deg. C for a period of 30 and 60 minutes of incubation. In general, an incubation of 30 deg. C or 60 deg. C (low or high) for a period of 30 minutes can be recommended for suppressing PPO activity. (author)

[en] In Purex process uranium and plutonium partitioning is done using uranous stablized with hydrazine. Though the stoichiometric quantity of uranous required is half of the mole of plutonium present, about twenty times excess is used in actual process due to instability of uranous in organic phase. Tertiary Butyl Hydroxy Quinone (TBHQ) is one of the organic soluble antioxidant which can destroy the oxidizing agent present in the organic medium. Preliminary experiments were carried out in laboratory to find out the suitability of TBHQ in stabilizing the uranous in TBP medium. (author)

No abstract available