Removal of uranium(VI) from aqueous solutions by nanoporous carbon and its chelating polymer composite

High surface area, ordered nanoporous carbon (CMK-3) and its chelating polymer composites were successfully prepared and utilized for the removal of U(VI) from aqueous solutions. Carboxymethylated polyethyleneimine (CMPEI) with a strong chelating property was introduced to the pore surface and inner pores of CMK-3 substrate. CMPEI-modified CMK-3 composite (CMPEI/CMK-3) was characterized by scanning electron microscopy and nitrogen sorption. U(VI) sorption capacity was significantly improved by the surface modification of CMK-3 by CMPEI. The CMPEI/CMK-3 showed enormously increased sorption capacities, compared with those of previous sorbents (e.g., surface-functionalized silicas). In particular, the CMPEI/CMK-3 showed a significantly high uranium retention property while allowing only about 1% U(VI) to leach out over a 4 month time period, when treated with polyacrylic acid.     

Interaction between the mouse homologue of CD99 and its ligand PILR as a mechanism of T cell receptor-independent thymocyte apoptosis

Here, we show that the interaction between two membrane proteins, the mouse homologue of CD99 (designated D4) and its ligand, paired immunoglobulin-like type 2 receptor (PILR), is one of the major mechanisms of thymocyte apoptosis. Using the polymeric fusion protein of PILR and IgG1 (PILR-Ig), we demonstrated that D4 ligation in the absence of T cell receptor (TCR) engagement leads to the induction of apoptosis, mainly at the double-positive stage of thymocytes. This was further confirmed by a blocking study in which blocking the interaction between D4 and PILR by soluble D4 protein led to reduced apoptosis in the fetal thymic organ culture with wild type and TCRα^-/- mice. Furthermore, the dissection of intracellular signaling pathway demonstrated that D4 cross-linking led to caspase activation without any change in mitochondrial membrane potential. Based on these data, we propose a mechanism for thymocyte depletion in which the interaction between D4 and PILR delivers an active signal.     

Influence of Solvent and Bridge Structure in Alkylthio‐Substituted Triphenylamine Dyes on the Photovoltaic Properties of Dye‐Sensitized Solar Cells

Three new triphenylamine dyes that contain alkylthio‐substituted thiophenes with a low bandgap as a π‐conjugated bridge unit were designed and synthesized for organic dye‐sensitized solar cells (DSSCs). The effects of the structural differences in terms of the position, number, and shape of the alkylthio substituents in the thiophene bridge on the photophysical properties of the dye and the photovoltaic performance of the DSSC were investigated. The introduction of an alkylthio substituent at the 3‐position of thiophene led to a decrease in the degree of redshift and the value of the molar extinction coefficient of the charge‐transfer band, and the substituent with a bridged structure led to a larger redshift than that of the open‐chain structure. The introduction of bulky and hydrophobic side chains decreased the short‐circuit photocurrent (J_sc), which was caused by the reduced amount of dye adsorbed on TiO₂. This resulted in a decrease in the overall conversion efficiency (η), even though it could improve the open‐circuit voltage (V_oc) due to the retardation of charge recombination. Furthermore, the change in solvents for TiO₂ sensitization had a critical effect on the performance of the resulting DSSCs due to the different amounts of dye adsorbed. Based on the optimized dye bath and molecular structure, the ethylene dithio‐substituted dye ( ATT3 ) showed a prominent solar‐to‐electricity conversion efficiency of 5.20 %.     

The M α and C-integrals

In this paper, we define the ${M_\alpha }$ -integral of real-valued functions defined on an interval [a, b] and investigate important properties of the ${M_\alpha }$ -integral. In particular, we show that a function f: [a, b] → R is ${M_\alpha }$ -integrable on [a, b] if and only if there exists an $AC{G_\alpha }$ function F such that F′ = f almost everywhere on [a, b]. It can be seen easily that every McShane integrable function on [a, b] is ${M_\alpha }$ -integrable and every ${M_\alpha }$ -integrable function on [a, b] is Henstock integrable. In addition, we show that the ${M_\alpha }$ -integral is equivalent to the C-integral.     

Oxidative Chlorination of Phenols with Hydrogen Chloride/m-Chloroperbenzoic Acid/N,N-Dimethylformamide System

The reaction of phenols with relevant amounts of HCl and m-chloroperbenzoic acid in DMF at room temperature gave regioselective chloro-substituted phenols in good yields.     

Effects of moisture on the glass transition temperature of polyurethane shape memory polymer filled with nano-carbon powder

One simple approach to produce electrically conductive polymers is to fill them with conductive powders. This paper investigates the effects of moisture on the glass transition temperature of a polyurethane shape memory polymer (SMP) filled with nano-carbon powders. It is found that the SMP composites before immersion in water have a slightly lower glass transition temperature, and in the mean time, the moisture fraction at the saturation point upon immersion is also lower. On the other hand, the moisture can remarkably reduce the glass transition temperature of the composites. Heating to over 180 °C is an effective way to remove the moisture, which also results in the glass transition temperature back to the original. As the glass transition temperature can be greatly reduced by moisture, a novel feature, namely, the water actutable recovery of SMP composites is also proposed based on this study.     

Viscoelastic characteristics of plasticized cellulose nanocomposites

The plasticization effects of cellulose diacetate composite systems including nanoparticles (montmorillonite, MMT) and plasticizers(diethyl phthalate, DEP) were investigated by the time–temperature superposition technique and viscoelastic modeling. Exhibiting the highest modulus value in the glass state, the viscoelastic modulus of the MMT nanocomposite rapidly decreased above the glass‐transition temperature (T_g). The Arrhenius‐type activation energy of pristine cellulose acetate showed the lowest value of activation energy and both DEP‐plasticized and MMT‐reinforced systems exhibited increased values of activation energy. Although the free volume fraction at the T_g decreased with the plasticizer content, it increased with the incorporation of MMT, seemingly preventing the polymer chains from being arranged in an ordered structure. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 59–65, 2005     

Methylene blue-conjugated hydrogel nanoparticles and tumor-cell targeted photodynamic therapy

Methylene blue‐conjugated polyacrylamide nanoparticles are prepared through a microemulsion polymerization, after conjugation of the dye with a monomer. The nanoparticles have a 50–60 nm diameter in solution. This conjugation method enables a large increase in loading of methylene blue per nanoparticle and also minimizes dye leaching out of the nanoparticle. Furthermore, the dye content can be controlled by variation of the dye amount, enabling a more refined control of the singlet oxygen production ability. The nanoparticles are coated with F3 peptides, which give specific targeting to selected tumor cells, 9L, MDA‐MB‐435, and F98, in vitro. In addition, MTT assays reveal that the nanoparticles have no dark toxicity but excellent PDT efficacy increasing with the nanoparticle dose and irradiation time.

     

The free energy of a reaction coordinate at multiple constraints: a concise formulation

The free energy as a function of the reaction coordinate (rc) is the key quantity for the computation of equilibrium and kinetic quantities. When it is considered as the potential of mean force, the problem is the calculation of the mean force for given values of the rc. We reinvestigate the PMCF (potential of mean constraint force) method which applies a constraint to the rc to compute the mean force as the mean negative constraint force and a metric tensor correction. The latter allows for the constraint imposed to the rc and possible artefacts due to multiple constraints of other variables which for practical reasons are often used in numerical simulations. Two main results are obtained that are of theoretical and practical interest. First, the correction term is given a very concise and simple shape which facilitates its interpretation and evaluation. Secondly, a theorem describes various rcs and possible combinations with constraints that can be used without introducing any correction to the constraint force. The results facilitate the computation of free energy by molecular dynamics simulations.     

Homogenization for a Class of Generalized Langevin Equations with an Application to Thermophoresis

We study a class of systems whose dynamics are described by generalized Langevin equations with state-dependent coefficients. We find that in the limit, in which all the characteristic time scales vanish at the same rate, the position variable of the system converges to a homogenized process, described by an equation containing additional drift terms induced by the noise. The convergence results are obtained using the main result in Hottovy et al. (Commun Math Phys 336(3):1259–1283, 2015), whose version is proven here under a weaker spectral assumption on the damping matrix. We apply our results to study thermophoresis of a Brownian particle in a non-equilibrium heat bath.