THE EFFECT OF NORFLURAZON ON PHOTOTROPIC REACTION IN Phaseolus aureus Roxb. SEEDLINGS

Abstract. The phototropic response of norflurazon-treated mung bean seedlings has been studied to evaluate the possible role of carotenoids, carotenoid-derived growth substances, or other factors in the perception/reaction system. Phototropism was slowed significantly in plants grown in white and blue light in the presence of norflurazon. This effect was evident in norflurazon-bleached seedlings, as well as in those whose pigment system was not affected, due to a shorter period of herbicide action. The possible modes of norflurazon action are discussed.     

Determination of critical micelle concentration of bile acid salts by micro-calorimetric titration

Critical micelle concentrations (CMC) of sodium salts of cholic, deoxycholic and chenodeoxycholic acids in phosphate buffer (pH 7.92) have been determined from microcalorimetric titration curves. The obtained values of 18.4±0.6, 5.3±0.2 and 7.0±0.2 mM, respectively, for Na cholate, Na deoxycholate and Na chenodeoxycholate are close to literature values obtained by other methods. CMC values for secondary micelles were also obtained. This microcalorimetric titration method gives highly reproducible results and rapid determination of CMC values of bile acid salts.     

Study on heterogeneous equilibria in saturated solutions of sparingly soluble diprotic acids

Heterogeneous equilibria in saturated solutions of sparingly soluble diprotic acids: 1,2-, 1,3- and 1,4-benzenedicarboxylic acid, and octanedioic acid, respectively, at ionic strengthI=1 (NaCl) and the temperature of 25 °C, have been investigated. The corresponding equilibrium constants were determined by the application of three independent methods: the formation function method, the method of protons bound to the acid in the solution and the solubility method. The results obtained by these three different methods are in good agreement.

---

Untersuchung heterogener Gleichgewichte in gesättigten Lösungen schwerlöslicher diprotischer Säuren

Zusammenfassung Es wurden die heterogene Gleichgewichte in gesättigten Lösungen schwerlöslicher diprotischer Säuren (Benzol-1,2-, -1,3- und-1,4-dicarbonsäuren und Oktandisäure) bei einer IonenstärkeI=1 (NaCl) und der Temperatur von 25 °C untersucht. Die entsprechende Gleichgewichtskonstanten wurden mit drei unabhängigen Methoden bestimmt: mit der Methode der Bildungsfunktion, der Methode der an die Säure in Lösung gebundenen Protonen, bzw. mit der Methode der Löslichkeitsbestimmung. Die erhaltenen Ergebnisse stehen in guter Übereinstimmung.

     

Factorial Design in Optimization of Chromatographic Separation of Ramipril and Its Impurities

In this paper optimization of chromatographic retention of ramipril and its five impurities employing factorial design is presented. On the basis of preliminary experiments three factors were chosen as inputs (acetonitrile content, pH of the mobile phase and buffer concentration) and retention factor as output. As optimal full factorial design 2³ was chosen, factors were examined at two different levels “low” and “high”. Three replications at zero level were added in order to check linearity and complete statistical tests. Relationship between inputs and output is presented in form of second order interaction model. Adequacy of model was explained using analysis of variance. After analysis of results optimal chromatographic conditions were set. Separations were conducted on a C₁₈ column with a mixture of acetonitrile and water phase (TEA in potassium dihydrogen phosphate) in ratio 23:77 v/v. Finally, the LC method was validated and applied for quality control analysis of commercially available tablets. The proposed method is simpler and faster as compared to existing official methods and therefore more adequate for routine control of ramipril during shelf life. Also a general approach which includes factorial design in method optimization offers a possibility for predicting and following the chromatographic behavior of such complex mixtures.     

Existence-uniqueness result for a nonlinear n-term fractional equation

We prove the existence-uniqueness of the solution to the nonlinear n-term time-fractional differential equation with constant coefficients in the Banach space C([0,T]),

(1)     

Affinity partitioning of a Cellulomonas fimi beta-mannanase with a mannan-binding module in galactomannan/starch aqueous two-phase system

A new approach in affinity separations was studied by partitioning of Cellulomonas fimi beta-mannanase (EC 3.2.1.78) containing a mannan-binding module in galactomannan/hydroxypropyl starch aqueous two-phase system. Comparison was made with a truncated version of C. fimi beta-mannanase which lacked the mannan-binding module. Results showed that affinity partitioning of the beta-mannanase was achieved due to biospecificity of the mannan-binding module towards the top phase containing galactomannan. Experiments were conducted at pH 8 to prevent enzyme degradation of the phase containing galactomannan. Removal of the top phase polymer was accomplished by beta-mannanase degradation allowed by shifting to the optimal pH 6. In the combination with the genetic fusion of any given protein to the mannan-binding module, the results envision a general procedure for primary affinity recovery of such fusion proteins.     

Automerization reaction of cyclobutadiene and its barrier height: an ab initio benchmark multireference average-quadratic coupled cluster study

The problem of the double bond flipping interconversion of the two equivalent ground state structures of cyclobutadiene (CBD) is addressed at the multireference average-quadratic coupled cluster level of theory, which is capable of optimizing the structural parameters of the ground, transition, and excited states on an equal footing. The barrier height involving both the electronic and zero-point vibrational energy contributions is 6.3 kcal mol(-1), which is higher than the best earlier theoretical estimate of 4.0 kcal mol(-1). This result is confirmed by including into the reference space the orbitals of the CC sigma bonds beyond the standard pi orbital space. It places the present value into the middle of the range of the measured data (1.6-10 kcal mol(-1)). An adiabatic singlet-triplet energy gap of 7.4 kcal mol(-1) between the transition state (1)B(tg) and the first triplet (3)A(2g) state is obtained. A low barrier height for the CBD automerization and a small DeltaE((3)A(2g),(1)B(1g)) gap bear some relevance on the highly pronounced reactivity of CBD, which is briefly discussed.     

Divergent synthesis of two novel muscarine analogues from D-glucose

A divergent synthesis of two new muscarine analogues bearing the (5S)-dioxolanyl isosteric group was achieved starting from d-glucose, enabling access to libraries of potential muscarinic agonists or antagonists. The key step of the synthesis involved a regioselective epoxide ring opening in 2,5:3,4-dianhydro derivatives 5 and 15 with LiAlH₄, whereby the natural stereochemistry of (+)-muscarine (1) and (−)-allo-muscarine (2) was efficiently established.     

Generalized Arago–Fresnel laws: the EME-flow-line description

We study experimentally and theoretically the influence of light polarization on the interference patterns behind a diffracting grating. Different states of polarization and configurations are considered. The experiments are analyzed in terms of electromagnetic energy (EME) flow lines, which can be eventually identified with the paths followed by photons. This gives rise to a novel trajectory interpretation of the Arago–Fresnel laws for polarized light, which we compare with interpretations based on the concept of “which-way” (or “which-slit”) information.