The ion and polymer content of polyelectrolyte multilayers constructed via layer-by-layer deposition have been directly probed using radioanalytical methods. Multilayers were fabricated using salt-containing or salt-free solutions. Charges on polyions quantitatively balance each other. As-deposited multilayers contain no salt ions within a limit of detection of a few ppm. All excess charge, which is reversed on each deposition step, resides at the surface. Surface charge controls the amount of polymer deposited and represents, on average, one-half of the charge within a single molecular layer. Internal charge can be regulated following deposition if one of the polyelectrolytes employed is redox-active, such as a polyviologen. Under electrochemical reduction, bulk charge compensation in a polyviologen/poly(styrene sulfonate) multilayer is preserved mainly by cation influx. Residual salt ions accumulate as conformational changes occur during repeated electrochemical cycling. When a thermally labile precursor to poly(p-phenylene vinylene) is incorporated as polycation, salt cation uptake is observed when positive charge is thermally eliminated from the multilayer. Evidence for disruption of this structure is observed when the charge density on one of the constituents approaches zero. For typical deposition times, usually up to 1 h, polymer deposition is kinetically irreversible, and the top layer is not stripped from the surface on exposure to its oppositely charged counterpart. These results provide further confirmation of extensive interpenetration and disorder as well as limited mobility within polyelectrolyte multilayers.

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In this study, we have demonstrated a simple ionic polymerization route for the fabrication of a magnetically separable adsorbent, that is, activated carbon/cobalt ferrite/alginate composite beads, for effective dye removal from aqueous solution. Adsorption characteristics of the as-fabricated magnetic beads were assessed by using methylene blue (MB) as an adsorbate. The isotherms, kinetics, and thermodynamics of the adsorption of MB onto the magnetic beads have been studied at various experimental conditions (initial dye concentration, contact time, solution pH, and temperature). The kinetics of the adsorption process was found to follow the pseudosecond-order kinetics. The equilibrium data fitted well to both the Langmuir and the Freundlich models. Various thermodynamic parameters such as the standard Gibbs energy (ΔG°), standard enthalpy (ΔH°), and standard entropy (ΔS°) changes were calculated. The prepared magnetic beads had a high magnetic sensitivity under an external magnetic field, which provides an easy and efficient way to separate the beads from aqueous solution.

This paper asks a new question: how can we control the collective behavior of self-organized multi-agent systems? We try to answer the question by proposing a new notion called 'Soft Control', which keeps the local rule of the existing agents in the system. We show the feasibility of soft control by a case study. Consider the simple but typical distributed multi-agent model proposed by Vicsek et al. for flocking of birds: each agent moves with the same speed but with different headings which are updated using a local rule based on the average of its own heading and the headings of its neighbors.Most studies of this model are about the self-organized collective behavior, such as synchronization of headings. We want to intervene in the collective behavior (headings) of the group by soft control. A specified method is to add a special agent, called a 'Shill', which can be controlled by us but is treated as an ordinary agent by other agents. We construct a control law for the shill so that it can synchronize the whole group to an objective heading. This control law is proved to be effective analytically and numerically. Note that soft control is different from the approach of distributed control. It is a natural way to intervene in the distributed systems. It may bring out many interesting issues and challenges on the control of complex systems.

Free-standing ultrathin films of a porphyrin homopolymer have been synthesized by interfacial polymerization of a mercaptoporphyrin. Coupling of 5,10,15,20-tetrakis(α-mercapto-p-tolyl)porphyrin at the water/chloroform interface by copper acetate yields continuous, flexible films after drying with supercritical CO2. These films are amorphous and retain many characteristics of the monomeric porphyrin, such as the property that they may be metalated. Spectroscopic evidence suggests efficient cross-linking of thiols through disulfide coupling occurs in these polyporphyrins to form a network. Polymerization is accompanied by the introduction of carbonyl functionality, probably the transformation of residual thiols to thioacetate by metal-mediated reaction with excess acetate ion. As an example of the catalytic properties of these polymers, they are shown to promote photooxidation of thietane to the corresponding sulfoxide by sensitizing singlet oxygen production.

Dear Dr. SchriddeWe would like to thank the Editorial team at Neuron for con nuing to assist us in pilo ng NEURON-D--R through the review process with a "minor revision" decision.We were happy to note that reviewer stated that "This already strong paper is much improved", expressing that "I do not want to stand in the way of the dissemina on of this important work". They suggested a new regression model, although they "realized this is a lot to ask". We have nevertheless implemented this to allay their remaining concerns. Reviewer is fully sa sfied with our work, and in the previous round remarked that "This is an outstanding work -both in terms of the techniques combina on and their applica on in alerts monkeys, the high quality data obtained from several visual areas and the important ques ons".It was heartening to see that reviewer recognized that "The work they report is a tour-de-force of several state-of-the-art methods, and I am sure the results will be very useful to anybody inves ga ng the cor cal representa on of color". Of concern to us however, the third referee now provides a novel set of more extensive, purportedly 'fault-finding' commentary. Much of this could and should have been raised in the first review. Several points betray selec ve reading of the manuscript, and are refuted simply by ci ng the exis ng text (and/or exis ng literature). The first round of review judged the logic of our study as predicated on the assump on that color and form are separately encoded in V . We were obliged to add Figure S in the last revision to address this misconcep on. However, the follow-up review gave no jus fica on for this major cri cism. The second round focused on the broad nature of color processing, yet appear agnos c to the unique value of the current study comparing across three successive visual areas of the same prepara on (a point borne out by the strong support obtained from Reviewers and ). We have nonetheless taken all ac onable sugges ons construc vely (for example, adding a new CIELAB analysis into Figures CD and B), and ensured that we carefully disambiguate any text where improvements can be made (please see our reply to the Reviewers appended to this le er).We would like to re-emphasize that we believe there is no precedent in the literature for such a thorough inves ga on of cor cal func onal organiza on along the visual hierarchy of V , V , and V for color representa on. The color vision system progressively removes the V color bias along the visual pathway and achieves spectral uniformity be er reflec ng color percep on. We have implemented whatever improvements we can, to meet the reviews' expecta on for publica on of this manuscript. We would also like to thank you very much for your me and support and are looking forward to hearing from you.

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Hydrogen/deuterium exchange behavior of human recombinant [C22A] FK506 binding protein (C22A FKBP) has been determined by protein fragmentation, combined with electrospray Fourier transform ion cyclotron resonance mass spectrometry (MS). After a specified period of H/D exchange in solution, C22A FKBP was digested by pepsin under slow exchange conditions (pH 2.4, 0°C). and then subjected to on-line HPLC/MS for deuterium analysis of each proteolytic peptide. The hydrogen exchange rate of each individual amide hydrogen was then determined independently by heteronuclear two-dimensional NMR on "N-enriched C22A FKBP. A maximum entropy method (MEM) algorithm makes it possible to derive the distributions of hydrogen exchange rate constants from the MS-determined deuterium exchange-in curves in either the holoprotein or its proteolytic segments. The MEM-derived rate constant distributions of C22A FKBP and different segments of C22A FKBP are compared to the rate constants determined by NMR for individual amide protons. The rate constant distributions determined by both methods are consistent and complementary, thereby validating protein fragmentation/mass spectrometry as a reliable measure of hydrogen exchange in proteins.