Study on Mass Transfer of Isopropylbenzene and Oxygen in a Two-Phase Partitioning Bioreactor in the Presence of Silicone Oil

A two-phase partitioning bioreactor to treat gas effluents polluted by volatile organic compound has been developed. In this work, both the mass transfer of isopropylbenzene (IPB) and oxygen have been considered in relation to their influence on the hydrodynamics of the reactor and the type of silicone oils used as a second phase. The synergistic effect of silicone oil and stirrer speed on the global oxygen mass transfer coefficient (K _L a) and gas holdup (up to 12%) have been investigated. The addition of 10% of low viscosity silicone oil (10 cSt) in the reactor does not significantly affect the oxygen transfer rate. The very high solubility of IPB in the silicone oil leads to an enhancement of driving force term, especially for high fraction of silicone oil. However, it does not seem useful to exceed a volume fraction of 10% since K _L a _IPB decreases sharply at higher proportions of silicone oil. K _L a _IPB and K _L a _O2 evolve in the same way with the proportion of silicone oil. These results confirm the potentialities of our bioreactor to improve both the oxygen and pollutant gas transfer in the field of the treatment of gaseous pollutants, even for highly concentrated effluents.     

Aging-related changes in the calorimetric profile of red blood cells from women with miscarriages

The backward-facing step or the sudden expansion in internal flows is an important problem in different areas. In this study, a porous baffle is mounted on the opposite wall of a sudden expansion to enhance heat transfer near the step. Unlike the solid baffle, which is extensively studied in the literature, the porous baffle has a lower pressure drop, and its properties can be tuned to reach the optimal prospected performance. Effects of different porous baffle geometrical parameters including its normalized height (H_b?=?0.5, 1.0, 1.5, 1.75), width (W_b?=?0.5, 1, 1.5, 2.0, 2.5), porous baffle-step relative distance (D?=?1, 2, 3, 4), Darcy number (10^?2, 10^?3, 10^?4, 10^?6), and Reynolds number (100, 200, 300, 400, 500) on the heat transfer and pressure drop are investigated. The simulation indicates that higher Reynolds numbers enhance more the heat transfer (35% improvement at Re?=?500 with respect to 10% at Re?=?100). Also, longer baffles can lead to higher heat transfer rates (5% improvement in H_b?=?0.5 with respect to 32% at H_b?=?1.5).

     

Long branching in poly(vinyl acetate) and poly(vinyl alcohol). III. Kinetic study of the branching reaction in the radical polymerization of vinyl acetate

The branching reaction in the radical polymerization of vinyl acetate was studied kinetically. Branching occurs by polymer transfer as well as terminal double-bond copolymerization. The chain-transfer constants to the main chain (C_p,2) and to the acetoxy methyl group (C_p,1) on the polymer were calculated on the basis of the experimental data described in the preceding paper giving C_p,2 = 3.03 × 10^?4, C_p,1 = 1.27 × 10^?4 at 60°C, and C_p,2 = 2.48 × 10^?4, C_p,1 = 0.52 × 10^?4 at 0°C. Chain transfer to monomer is important with respect to the formation of the terminal double bond. The total values of transfer constants to the α- or β-position in the vinyl group and the acetoxymethyl group in vinyl acetate was determined to be 2.15 × 10^?4 at 60°C. The transfer constant to the acetyl group in the monomer (C_m,1) was also evaluated to be 2.26 × 10^?4 at 60°C from the quantitative determination of the carboxyl terminals in PVA. These facts suggest that the chain-transfer constant to the α- or β-position in the monomer (C_m,2) is nearly equal to zero within experimental error. Copolymerization reactivity parameters of the terminal double bond were also estimated. In conclusion, it has become clear that the formation of nonhydrolyzable branching by the terminal double-bond reaction can be almost neglected, and hence that the long branching in PVA is formed only by the polymer transfer mechanism. On the other hand, a large number of hydrolyzable branches in PVAc are prepared by the terminal double-bond reaction rather than by polymer transfer.     

Photopolymerization of methyl methacrylate initiated by sulphur dioxide

In catalytic concentrations (10^?5?10^?4 mol l^?1) sulphur dioxide induces polymerization of MMA, particularly on photoactivation. The effective initiating species appears to be the monomer-SO₂ complex rather than free SO₂. A mechanism involving biradical initiation by decomposition of the initiating species, linear propagation in two directions, and significant termination of growing chains by chain transfer with initiating species has been suggested. The initiator transfer constant is 1.6 at 40°.     

High‐Field Pulsed EPR Spectroscopy for the Speciation of the Reduced [PV2Mo10O40]6− Polyoxometalate Catalyst Used in Electron‐Transfer Oxidations

An in‐depth spectroscopic EPR investigation of a key intermediate, formally notated as [PV^IVV^VMo₁₀O₄₀]^6? and formed in known electron‐transfer and electron‐transfer/oxygen‐transfer reactions catalyzed by H₅PV₂Mo₁₀O₄₀, has been carried out. Pulsed EPR spectroscopy have been utilized: specifically, W‐band electron–electron double resonance (ELDOR)‐detected NMR and two‐dimensional (2D) hyperfine sub‐level correlation (HYSCORE) measurements, which resolved ⁹⁵Mo and ¹⁷O hyperfine interactions, and electron–nuclear double resonance (ENDOR), which gave the weak ⁵¹V and ³¹P interactions. In this way, two paramagnetic species related to [PV^IVV^VMo₁₀O₄₀]^6? were identified. The first species (30–35 %) has a vanadyl (VO²⁺)‐like EPR spectrum and is not situated within the polyoxometalate cluster. Here the VO²⁺ was suggested to be supported on the Keggin cluster and can be represented as an ion pair, [PV^VMo₁₀O₃₉]^8?[V^IVO²⁺]. This species originates from the parent H₅PV₂Mo₁₀O₄₀ in which the vanadium atoms are nearest neighbors and it is suggested that this isomer is more likely to be reactive in electron‐transfer/oxygen‐transfer reaction oxidation reactions. In the second (70–65 %) species, the V^IV remains embedded within the polyoxometalate framework and originates from reduction of distal H₅PV₂Mo₁₀O₄₀ isomers to yield an intact cluster, [PV^IVV^VMo₁₀O₄₀]^6?.     

How Do Defects in Carbon Nanostructures Regulate the Photoinduced Electron Transfer Processes? The Case of Phenine Nanotubes

Photoinduced electron transfer is studied in a series of inclusion complexes of structurally modified phenine nanotubes ( pNT ) with C₇₀ using the TD-DFT method. Analysis of electronic properties of the complexes shows that the electron transfer is infeasible in pNT_4d⊃C₇₀ built on the tetrameric array of [6]cyclo-meta-phenylene ([6]CMP) units. However, replacing one or more [6]CMP units with a coronene moiety enables electron transfer from pNT to C₇₀ . The generation of the charge separated states from the lowest locally excited states occurs on a sub-nanosecond time scale. Depending on the number of the [6]CMP units, the charge recombination rate varies from 1.8 ⋅ 10⁷ to 3.1 ⋅ 10² s⁻¹, i. e., five orders of magnitude.     

Emission from an excited triplet state during ECL

The application of Marcus theory of electron transfer reactions for the case of radical ion chemiluminescence of 9,10-diphenylanthracene (DPA) gives a high rate constant value (10⁹–10¹⁰ M^?1 s^?1) for the formation of the second triplet state (T₂). It is suggested that the near infrared emission observed during electrochemiluminescence of DPA is due to T₂ → T₁ fluorescence based on the high yield of T₂ (≈0.7) in the electron transfer reaction.     

黄曲霉素B2分子吸附在银团簇的表面增强拉曼散射机理

采用密度泛函理论（DFT）B3LYP方法,6-311G（d,p）（C,H,O）/LANL2DZ（Ag）基组,计算了黄曲霉素B₂（AFB₂）分子吸附在Ag₂团簇的表面增强拉曼散射（SERS）光谱和预共振拉曼光谱,并与实验结果比较. 结果显示：AFB₂分子在基态Ag₂团簇表面吸附时,增强因子最大达到10²,对应吡喃（pyrane）环C=O伸缩振动,主要是由AFB₂分子周围化学环境改变而引起的基态静极化率改变导致的化学增强. 不同激发波长下的AFB₂分子预共振拉曼光谱的增强强度不同：电荷转移态激发波长为1144 和544 nm时拉曼信号增强了10²倍,而选择电荷转移预共振波长432和410 nm作为入射光时,其拉曼信号增强了10⁴倍,增强机理为银团簇和黄曲霉素分子之间的电荷转移共振增强. 因此通过改变入射光波长,选择电荷转移共振激发波长,更有利于强致癌物AFB₂分子的痕量检测.     

Synthesis of E-homoallylic alcohols, γ-hydroxyketones,and cyclopropyl ketones from 3-diphenylphosphinoyl (Ph2PO) propanols by acyl transfer

Carboxyl transfer (O→C) on 3-Ph₂PO propyl esters (9) gives an intermediate (10) from which the Ph₂PO group may be removed by the Horner-Wittig reaction or by Ph₂PO transfer (C→O) to give the title compounds.     

Intermolecular interaction between squarylium cyanine and porphyrin

In this paper, the interaction between squarylium cyanine and porphyrin in chloroform is investigated by absorption and fluorescence spectroscopy. Emphasis has been put on the mechanism of intermolecular energy transfer. The overlap integral J between the absorption spectrum of squarylium cyanine and the fluorescence spectrum of porphyrin was calculated, which reveals that the singlet-singlet energy transfer may occur from porphyrin to squarylium cyanine in solution. In comparison of the observed rate constant [kqII=6.1 ×1013 (mol/L)-1·s-1] for fluorescence quenching of porphyrin by squarylium cyanine with the diffusion rate constant in chloroform [kdif=1.1×1010 (mol/L)-1·s-1] and the rate of energy transfer [ket≤6.7×104 (mol/L)-1·s-1 in the experimentally dilute solutions] estimated from Forster formula, the possibility of energy transfer by electron exchange or/and coulombic mechanism could be excluded. So it has been definitely convinced that the intermolecuiar energy transfer between them is     

The interface behavior of hemoglobin at carbon nanotube and the detection for H(2)O(2)

Direct electrochemistry of hemoglobin (Hb) is observed at carbon nanotube (CNT) interface. The adsorbing Hb can transfer electron directly at CNT interface compared with common carbon material. The heterogeneous electron transfer rate constant k of Hb can be calculated as 0.062 s⁻¹, the transfer coefficient α is 0.21 and the average surface coverage of Hb on CNT surface is 3.58 × 10⁻⁹ ± 2.7 × 10⁻¹⁰ mol/cm². It is found that the adsorbing Hb still keeps its catalytic activity to H₂O₂. This sensor was used to detect H₂O₂. The apparent Michaelis-Menten constant is calculated as 6.75 × 10⁻⁴ mol L⁻¹.     

Study on the behavior of129I in the terrestrial environment

Transfer parameters for dose assessment such as deposition velocity (V _g), fraction of directly deposited on plants to the edible parts (r) and transfer factors (B _iv) have been evaluated. Deposition velocity under drying and wet conditions was evaluated about 0.8 cm/s. Fraction of directly deposited on plants and transfer factors in plants showed a lognormal distribution. Geometric means of fraction of deposited in rice, leafy vegetable and grass were <9·10^–3, 0.2 and about 9·10^–2, respectively. Geometric mean of the transfer factor in leafy vegetable was about 3·10^–2. These results were compared with the parameters given in the US NRC Regulatory Guide and previous literature values. The results showed that the fraction of directly deposited on plants were smaller than the recommended value in the NRC Regulatory Guide. They also showed that the deposition velocity and transfer factors were almost similar to the results reported in the literature.     

Electrochemical study of isopoly and heteropoly anion transfer across the water | nitrobenzene interface. Part II. Vanadium-containing heteropolytungstate anions

The electrochemical transfer behaviour of vanadium-containing heteropolytungstate anions [PW_12−xV_xO₄₀]^(3+x)− (x = 1−4) across the water | nitrobenzene interface has been investigated by cyclic voltammetry and chronopotentiometry with cyclic linear current scanning. The transfer of PW₁₁V₁O⁴⁻₄₀, HPW₁₀V₂O⁴⁻₄₀, H₂PW₁₀V₂O³⁻₄₀, H₃PW₉V₃O³⁻₄₀ and H₄PW₈V₄O³⁻₄₀ across the water | nitrobenzene interface can be observed within the potential window. The effects were observed of pH in the water phase on the transfer behaviour and the formation of vanadium-containing heteropolytungstate anions in solution. Heteropolytungstate anions become more stable due to their involving the vanadium atom. The degree of protonation and the dissociation constant of the trivalent vanadium-containing heteropolytungstate anion of protonation increase with increasing vanadium content. The transfer processes are diffusion-controlled. The standard transfer potential, the standard Gibbs energy and the dissociation constant for vanadium-containing heteropolytungstate anions have been obtained and the transfer mechanisms are discussed.     

Thermodynamic and aggregation behavior of mixed micellar systems of sodium decanoate and ethoxylated alcohols in water at 25°C

Densities and ultrasonic velocities of binary aqueous systems of sodium decanoate (C₁₀Na), of a medium chain length alkoxyethanol with varying number of ethylene oxide groups (C₄EO_0-3), and of ternary systems of these compounds have been measured as a function of surfactant and alcohol concentrations at 25°C. The derived apparent molar volume and molar adiabatic compressibility properties of C₁₀Na in water were fitted with a mass-action model to obtain the thermodynamic micellization parameters of C₁₀Na. The infinite dilution transfer molar volume and transfer molar adiabatic compressibility properties of C₄EO_0-3 from water to aqueous C₁₀Na solutions were obtained from the corresponding apparent molar properties using a chemical equilibrium model. The results of simulating the experimental transfer function data of these alcohols at a given low concentration of 0.05m_A show that the solubilization of C₄EO_0-3 compounds in C₁₀Na micelles is enhanced by increasing the number of ethylene oxide groups (EO) in the alcohol. The mean aggregation number of C₁₀Na, which is 34 in the absence of alcohol, remains unchanged in the presence of 0.05m_A while the average number of alcohol molecules per micelle increases steadily as a function of the number of EO groups in the alcohol.     

Luminescence properties of Eu2+, Sn2+, and Pb2+ in SrB6O10 and Sr1 − xMnxB6O10

The luminescence properties of Eu²⁺, Sn²⁺, and Pb²⁺ in SrB₆O₁₀ have been studied both at room-temperature and liquid-helium temperature and the decay times of Sn²⁺ and Pb²⁺ in this matrix have been measured and analyzed. According to the emission spectrum of Eu²⁺ there seems to be three different cation sites in SrB₆O₁₀. Europium, tin, and lead were also used as sensitizers for Mn²⁺ and the energy transfer processes were characterized. Eu²⁺-Mn²⁺ energy transfer was inefficient due to the transfer within different Eu²⁺ centers. The sensitization action of Sn²⁺ and Pb²⁺ on Mn²⁺ was different because lead-lead energy transfer occurs (even at 4.2 K) but tin-tin transfer can be neglected. A fast diffusion model for the Pb²⁺ system is suggested.     

Triplet excited states of nitronaphthalenes. II. b-Nitronaphthalene

Nanosecond flash photolysis of b-nitronaphthalene (b-NO₂C₁₀H₇) in nonpolar and polar solvents shows a transient species with maximum absorption and lifetime dependent on solvent polarity. In deaerated n-hexane the absorption maximum and lifetime (1/k) are 425 nm and 530 nsec, while in deaerated ethanol the corresponding values are 470 nm and 1.7 ·sec. This transient absorption is attributed to the triplet excited state of b-NO₂C₁₀H₇, and the observed red shift as well as its longer lifetime in polar solvents are indicative of the intramolecular charge transfer character of this state. The change of dipole moment accompanying the transition T₁ → T_n, as well as rate constants for electron and proton transfer reactions involving the T₁ state of b-NO₂C₁₀H₇, were determined. The spectroscopic and kinetic data obtained in this work indicate that the triplet state of b-NO₂C₁₀H₇ behaves like a n-π* state in nonpolar media, while in polar solvents the n-π* character of the state is reduced with a simultaneous increase in the charge transfer character.     

A capillary electrophoresis strategy to sensitively detect dynamic properties of coiled coil polypeptides

The self‐assembly behavior of polypeptides plays an essential role to form biological and functional macromolecules, which have attracted a lot of attention due to their excellent characters. Understanding the polypeptide self‐assembly systems and dynamic behaviors is fundamental to improve the potential of biomedical applications. In this work, coiled coil polypeptides PC₁₀ and PC₁₀P were designed and biosynthesized. PC₁₀ and PC₁₀P could form nanogels when the concentration of polypeptides was less than 2% (m/v). The dynamic behaviors of PC₁₀ and PC₁₀P were measured by Förster resonance energy transfer method based on a capillary electrophoresis system. The Förster resonance energy transfer efficiency of this system was 60.4%, and the distance of self‐assembled domains in the polypeptides was calculated as 6.14 nm, demonstrating that the exchange behavior occurred between two different polypeptides containing the same coiled coil region.     

Equations for the Partition of Neutral Molecules, Ions and Ionic Species from Water to Water–Ethanol Mixtures

Equations set up for the transfer of neutral solutes from water to water?Cethanol mixtures can also be used to correlate the transfer of ions and ionic species, as log₁₀ P, where P is the partition coefficient. Only two additional terms are required in the equations, one for anions and one for cations. The extended equations can fit log₁₀ P values for anions and cations with a standard deviation of about 0.2 to 0.3 log units for transfer of 41 anions and cations from water to various water?Cethanol mixtures from 10?% ethanol to 100?% ethanol by volume. The log₁₀ P values for carboxylate anions and protonated amine cations as obtained from the variation of pK _a with solvent are quite compatible with log₁₀ P values for simple anions and cations.     

A Supramolecular [10]CPP Junction Enables Efficient Electron Transfer in Modular Porphyrin–[10]CPP⊃Fullerene Complexes

Efficient photoinduced electron transfer was observed across a [10]cycloparaphenylene ([10]CPP) moiety that serves as a rigid non‐covalent bridge between a zinc porphyrin and a range of fullerenes. The preparation of iodo‐[10]CPP is the key to the synthesis of a porphyrin–[10]CPP conjugate, which binds C₆₀, C₇₀, (C₆₀)₂, and other fullerenes (K_A>10⁵ m ^?1). Fluorescence and pump–probe spectroscopy revealed intramolecular energy transfer between CPP and porphyrin and also efficient charge separation between porphyrin and fullerenes, affording up to 0.5 μs lifetime charge‐separated states. The advantage of this approach towards electron donor–acceptor dyads is evident in the case of dumbbell‐shaped (C₆₀)₂, which gave intricate charge‐transfer behavior in 1:1 and 2:1 complexes. These results suggest that [10]CPP and its cross‐coupled derivatives could act as supramolecular mediators of charge transport in organic electronic devices.     

DIRECT OBSERVATION OF ELECTRON TRANSFER ACROSS A LIPID BILAYER: PULSED LASER PHOTOLYSIS OF AN ASYMMETRIC VESICLE SYSTEM CONTAINING CHLOROPHYLL,METHYL VIOLOGEN AND EDTA*

Abstract— Suspensions of vesicles composed of chlorophyll a (Chi) and phospholipid that were asymmetric with respect to aqueous solutions of methyl viologen (MV₂₊), an electron acceptor, and EDTA, an electron donor, were investigated using both flash and steady-state photolysis techniques. It was shown that Chl-photosensitized electron transfer occurred across the walls of the vesicles from EDTA to MV₂₊. Flash photolysis indicated that MV₂₊ dissolved in the interior aqueous compartments of the vesicles oxidized only those triplet excited state Chi molecules that were dissolved in the inner monolayers of the vesicle walls. The resultant radical products, Chi₊ and MV₊, recombined with a halftime of the order of 10_-4s. EDTA, added externally to the vesicles, competed effectively with MV₊ as a reducing agent for Chl₊. This places a lower limit of 10₄ s_-1 on the rate constant for transmembrane electron transfer. Compartmentalization by the vesicle wall of the competing pathways for the reduction of Chi₊ resulted in a nonlinear dependence of the rate constant of Chl₊ decay on EDTA concentration. The magnitude of the rate constant of electron transfer through the membrane and the way that the kinetics of Chl₊ decay depended on the concentration of Chi in the membrane strongly suggest that the electron transfer occurred by electron exchange between Chi and Chl₊.