Colloid Transport in Porous Media: A Review of Classical Mechanisms and Emerging Topics

To celebrate the tenth anniversary of InterPore, we present an interdisciplinary review of colloid transport through porous media. This review aims to explore both classical colloid transport and topics that fall outside that purview and thus offer transformative insights into the physics governing transport behavior. First, we discuss the unique colloid characteristics relative to molecules and larger particles. Then, the classical advection–dispersion–filtration models (both conceptual and mathematical) of colloid transport are introduced as well as anomalous transport behaviors. Next, the forces of interaction between colloids and porous media surfaces are discussed. Fourth, applications that are interested in maximizing the transport of colloids through porous media are considered. Then the concept of motile, active biocolloids is introduced, and finally, colloid swarming as a newly recognized mode of transport is summarized.

     

Decay Properties of the Connectivity for Mixed Long Range Percolation Models on ℤ<Superscript><Emphasis Type="Italic">d</Emphasis></Superscript>

In this short note we consider mixed short-long range independent bond percolation models on ℤ ^k+d . Let p _uv be the probability that the edge (u,v) will be open. Allowing a x,y-dependent length scale and using a multi-scale analysis due to Aizenman and Newman, we show that the long distance behavior of the connectivity τ _xy is governed by the probability p _xy . The result holds up to the critical point.     

Selective excitation in pulsed EPR of a spin-correlated triplet-radical pair

Experiments are described in which a low-amplitude microwave pulse excites only one out of three allowed transitions of the quinone radical (Q(A)(-)) in a spin-correlated triplet-radical pair 3PQ(A)(-) of the bacterial photosynthetic reaction center. A second high-amplitude pulse produces a FID whose temporal shape is strongly modulated with frequencies determined by electron-electron dipolar interaction in the pair. The FID is detected in both the in-phase and the out-of-phase channels. The out-of-phase FID is a result of switching off the magnetic dipolar interaction between 3P and Q(A)(-) due to decay of 3P during the time interval between the two pulses. Refocusing of FID by an additional non-selective pulse allows a dead-time free measurement of this modulation. The influence of the dead-time problem on the distance determination is discussed.     

Wärmeleitfähigkeit von Polyvinylchlorid mit und ohne Weichmacher im Temperaturbereich von 70 bis 360 °K

Zusammenfassung Es wird eine halbautomatische Apparatur für die Messung der W?rmeleitf?higkeit von Kunststoffen durch gro?e Temperaturbereiche beschrieben. Die damit bestimmte W?rmeleitf?higkeitskonstante von weichgestelltem PVC wird als Funktion des Weichmachergehaltes und der Temperatur zwischenT=60 °K (fester Sauerstoff) undT=100 °C=373 °K angegeben. Vorgetragen auf der Arbeitssitzung des Faehausschusses „Physik der Hoehpolymeren“ im Verband der Deutsehen Physikalischen Gesellschaften zur Physikertagung München am 7. September 1956.     

4‐Heptanone cyclic diperoxide: Improved preparation method and solvent effect on its thermolysis in solution

Cyclic organic peroxides have interesting pharmacological properties and are used at industrial level as polyfunctional initiators of polymerization, and so their preparation through novel methods has attracted the attention of numerous researchers. White crystals of 4‐heptanone cyclic diperoxide (HDP) can be obtained in acidic media at ?1°C by a reaction between 4‐heptanone and hydrogen peroxide. Its thermal decomposition was studied in acetone, cyclohexane, acetonitrile, ethyl acetate, ethanol, 2‐propanol, 2‐butanol, and 1,4‐dioxane at temperatures higher than 120°C, showing a behavior accordingly with a pseudo‐first‐order kinetic law up to at least 80% HDP conversion. It was demonstrated that an increase in solvent polarity is accompanied by an increase in reaction rates. The effect of solvent polarity on the thermal decomposition rate constant values can be associated with a reaction mechanism involving a more dipolar‐activated complex than the diperoxide initial molecule. The activation parameters varied widely from 31.2 to 46.6 kcal mol^?1 and ?1.33 to 31.7 cal mol^?1 K^?1 when going from ethanol to cyclohexane as reaction solvents, respectively. An enthalpy–entropy compensation effect was observed in all solvents. Specific interactions between the oxygen atoms from the peroxidic bond and the hydrogen atom bonded to C2 and/or from the OH group can be taken into account to explain that the existence of the compensation effect does not mean that an isokinetic relationship consequently can be established. The kinetic results showed that an isokinetic relationship is observed only for a group of solvents. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 657–666, 2011     

Nitrite‐Selective Electrode Based On Cobalt(II) tert‐Butyl‐Salophen Ionophore

A series of polymeric nitrite‐selective electrodes containing a new lipophilic ionophore Co(II) tert‐butyl‐salophen is reported. The stability of Co(II) ionophores within a PVC‐based membrane was investigated by leaching experiments. Different membrane compositions were explored in order to reach the lowest possible limit of detection for a PVC‐based nitrite selective polymeric membrane electrode containing this ionophore. The optimal electrode showed a limit of detection of 2×10^?6 M and exhibited four orders of magnitude of discrimination over nitrate, chloride and bromide. The electrodes were evaluated in undiluted human urine and attest to the robustness of the ionophore.     

Prolate and oblate 10 isomers in Sm78 and Gd78

The N = 78 isotones ¹⁴⁰Sm and ¹⁴²Gd have been studied with -particle- and HI-induced reactions. In both nuclei two close-lying 10⁺ isomers at 3.2 MeV have been established, and from the feeding E2 cascades they are characterized as the prolate and the oblate excitations. A third E2 cascade feeding into the ¹⁴²Gd 8⁺ state is interpreted as the continuation of the collective ground state sequence that might assume the properties of a perfect deformed rotor for spins above 10.     

High spin states in the doubly-closed shell nucleus146Gd

High spin states of¹⁴⁶Gd, populated in heavyion induced reactions, have been investigated by means of in-beamγ-ray spectroscopy using the Compton-suppressed germanium detector arrays OSIRIS and ESSA30. 35 new levels and 47 new transitions could be placed in the level scheme. In addition to the extension to very high spins, a new cascade has been observed at intermediate spins.