Light-induced changes in cytochrome b-559 in spinach chloroplasts

Abstract— In isolated spinach chloroplasts, the reduction of cytochrome b-559 by System II and its oxidation by System I can be observed when electron acceptor concentration limits System I activity and when one of a particular class of uncoupling agents is present. This class includes CCCP, desaspidin, Triton X-100 and antimycinA; but not simple amines or atebrin. The effect of the uncoupler is to speed the cytochrome b-559 oxidation rate. In addition, the rate of the off-response of the light-induced P518 absorbance change is increased. To explain these findings, an electron transfer scheme is proposed having two distinct pathways between System II and System I.     

Fullerohelicates: a new class of fullerene-containing supermolecules

A multicomponent array made of a bis-copper(I) helicate core and two peripheral fullerene subunits has been prepared and electron transfer from the photoexcited Cu(I)-complexed unit to C60 occurs.     

Synthesis,design of experiments and optimization of heterogeneous Fenton-like degradation of tartrazine by MgFe2O4 nano-catalyst

In this work, magnesium ferrites nanoparticles (MgFe₂O₄ NPs) were successfully fabricated by sol-gel auto-combustion (SGAC) method and were used in heterogeneous Fenton-like degradation of tartrazine. The obtained products were characterized using XRD, FTIR, SEM and EDX. XRD studies confirmed that the synthesized MgFe₂O₄ NPs had a cubic spinel structure. The average crystallite size was evaluated using the Debyee Scherrer formula and found to be in the range 16.18–28.55 nm. In FTIR spectra, two primary absorption bands at 571 cm^?1 and 415 cm^?1 were observed. The spinel ferrites are characterized by these bands and the EDX confirms the presence of the desired elements Mg, Fe, and O. The influences of operating parameters were examined using the Box Behnken statistical design (BD), including magnesium ferrite dosage (0.04–0.12 g/L), tartrazine concentration (30–50 mg/L) and H₂O₂ concentration (3.53–7.06 mM). Using analysis of variance, a significant quadratic model was created. Optimum conditions were magnesium ferrite dosage of 0.092 g/L, tartrazine concentration of 30.21 mg/L and H₂O₂ concentration of 6.66 mM, respectively. The predicted degradation efficiency within the optimum conditions as established by the suggested model was 98.4%. Confirmatory tests were carried out and the degradation efficiency of 98.9% was observed, which was in good agreement with the model's prediction. After five recuperation and reapplications, the catalyst's degradation efficiency remains stable. These findings indicate that a heterogeneous Fenton-like process utilizing MgFe₂O₄ is effective in advanced wastewater treatment.     

Measurement Bias on Nanoparticle Size Characterization by Asymmetric Flow Field-Flow Fractionation Using Dynamic Light-Scattering Detection

In this work, we highlight the influence of the particle–particle interaction on the retention behavior in asymmetric flow field-flow fractionation (A4F) and the misunderstanding considering the size determination by a light-scattering detector (static and dynamic light scattering) by comparing fullerene nanoparticles to similar sized polystyrene nanoparticle standards. The phenomena described here suggest that there are biases in the hydrodynamic size and diffusion determination induced by particle–particle interactions, as characterized by their virial coefficient. The dual objectives of this paper are to (1) demonstrate the uncertainties resulting from the current practice of size determination by detectors coupled to an A4F system and (2) initiate a discussion of the effects of particle–particle interactions using fullerene nanoparticles on their characterization as well as their origins. The results presented here clearly illustrate that the simple diffusion coefficient equation that is generally used to calculate the hydrodynamic size of nanoparticles (NPs) cannot be considered for whole fractograms according to their size distribution. We tried to identify particle interactions that appear during fractionation and demonstrated using the fully developed diffusion coefficient equation. We postulate that the observed interaction-dependent retention behavior may be attributed to differences in the virial coefficient between NPs and between NPs and the accumulation wall (membrane surface) without quantifying it. We hope that our results will stimulate discussion and a reassessment of the size determination procedure by A4F-LS to more fully account for all the influential material parameters that are relevant to the fractionation of nanoscale particles by A4F.     

Edge colorings of graphs embeddable in a surface of low genus

In this paper, by using the Discharging Method, we show that any graph with maximum degree Δ 8 that is embeddable in a surface Σ of characteristic χ(Σ) 0 is class one and any graph with maximum degree Δ 9 that is embeddable in a surface Σ of characteristic χ(Σ) = − 1 is class one. For surfaces of characteristic 0 or −1, these results improve earlier results of Mel'nikov.     

Ruled 4-manifolds and isotopies of symplectic surfaces

We study symplectic surfaces in ruled symplectic 4-manifolds which are disjoint from a given symplectic section. As a consequence, in any symplectic 4-manifold, two homologous symplectic surfaces which are C ⁰ close must be Hamiltonian isotopic.     

Existence and stability of foliations by <Emphasis Type="Italic">J</Emphasis>-holomorphic spheres

We study the existence and stability of holomorphic foliations in dimension greater than 4 under perturbations of the underlying almost-complex structure. An example is given to show that, unlike in dimension 4, J-holomorphic foliations are not stable under large perturbations of almost-complex structure.     

Colouring a graph frugally

We prove that any graph with maximum degree sufficiently large, has a proper vertex colouring using +1 colours such that each colour class appears at most log⁸ times in the neighbourhood of any vertex. We also show that for 1, the minimum number of colours required to colour any such graph so that each vertex appears at most times in the neighbourhood of any vertex is (+^1+1//), showing in particular that when =log/loglog, such a colouring cannot always be achieved with O() colours. We also provide a polynomial time algorithm to find such a colouring. This has applications to the total chromatic number of a graph.The second two authors were supported by NATO Collaborative Research Grant #CRG950235.     

Strict majority functions on graphs

An opinion function on a graph G = (V, E) is a function f: V → {−1, +1}. The vote of a vertex v is the sum of these function values over the closed neighborhood of v. A strict majority function on a graph G is an opinion function for which more than half of the vertices have a positive vote. The strict majority number of G is the minimum sum of the values in a strict majority function of G. We prove the conjecture of Cockayne and Mynhardt (Ars. Combin. 43 (1996), 235–245) that every tree has strict majority number at most 2. We also prove that every graph has strict majority number at most 4. Both bounds are sharp. © 1998 John Wiley & Sons, Inc. J Graph Theory 28: 49–56, 1998     

The first three‐dimensional vanadium hypophosphite

The title synthesized hypophosphite has the formula V(H₂PO₂)₃. Its structure is based on VO₆ octahedra and (H₂PO₂)⁻ pseudo‐tetrahedra. The asymmetric unit contains two crystallographically distinct V atoms and six independent (H₂PO₂)⁻ groups. The connection of the polyhedra generates [VPO₆H₂]⁶⁻ chains extended along a, b and c, leading to the first three‐dimensional network of an anhydrous transition metal hypophosphite.