Removal of solvent-based ink from printed surface of HDPE bottles by alkyltrimethylammonium bromides: effects of surfactant concentration and alkyl chain length

Three alkyltrimethylammonium bromides (i.e., dodecyl-, tetradecyl-, and hexadecyltrimethylammonium bromide or DTAB, TTAB, and CTAB, respectively) were used to remove a blue solvent-based ink from a printed surface of high-density polyethylene bottles. Either an increase in the alkyl chain length or the surfactant concentration was found to increase the deinking efficiency. Complete deinking was achieved at concentrations about 3, 8, and 24 times of the critical micelle concentration (CMC) of CTAB, TTAB, and DTAB, respectively. For CTAB, ink removal started at a concentration close to or less than its CMC and increased appreciably at concentrations greater than its CMC, while for TTAB and DTAB, significant deinking was only achieved at concentrations much greater than their CMCs. Corresponding to the deinking efficiency of CTAB in the CMC region, the zeta potential of ink particles was found to increase with increasing alkyl chain length and concentration of the surfactants, which later leveled off at some higher concentrations. Wettability of the surfactants on an ink surface increased with increasing alkyl chain length and concentration of the surfactants. Lastly, solubilization of ink binder in the surfactant micelles was found to increase with increasing alkyl chain length and surfactant concentration. We conclude that adsorption of surfactant on the ink pigment is crucial to deinking due to modification of wettability, zeta potential, pigment/water interfacial tension, and dispersion stability. Solubilization of binder (epoxy) into micelles is necessary for good deinking because the dissolution of the binder is required before the pigment particles can be released from the polymer surface.     

Mass spectrometry for the detection of differentially expressed proteins: a comparison of surface-enhanced laser desorption/ionization and capillary electrophoresis/mass spectrometry

The discovery of biomarkers is currently attracting much interest as it harbors great potential for the diagnosis and monitoring of human diseases. Here we have used two advanced mass spectroscopy based technologies, surface enhanced laser desorption ionization (SELDI-MS) and capillary electrophoresis/mass spectrometry (CE/MS), to obtain proteomic patterns of urine samples from patients suffering from membranous glomerulonephritis (MGN) and healthy volunteers. The results indicate that CE/MS analysis is able to display a rich and complex pattern of polypeptides with high resolution and high mass accuracy. In order to analyze these patterns, the MosaiqueVisu software was developed for peak identification, deconvolution and the display of refined maps in a three-dimensional format. The polypeptide profiles obtained with SELDI-MS from the same samples are much sparser and show lower resolution and mass accuracy. The SELDI-MS profiles are further heavily dependent on analyte concentration. SELDI-MS analysis identified three differentially expressed polypeptides, which are potential biomarkers that can distinguish healthy donors from patients with MGN. In contrast, approximately 200 potential biomarkers could be identified by CE/MS. Thus, while SELDI-MS is easy to use and requires very little sample, CE/MS generates much richer data sets that enable an in-depth analysis.     

WeightedL p closure theorems for spaces of entire functions

For a fixed weight Δ(dx) onR ¹ and a linear space ℋ ⊆L ^p(Δ) of entire functions that is closed under difference quotientsh(·)→(z−·) ⁻¹[h(z)−h(·)], theL ^p(Δ) closure of ℋ is studied and characterized in terms of the normsL(z), (z∈C ¹ of the evaluation functionalsh→h(z),h∈ℋ. Partially supported by DA-ARO-31-124-71-6182 and NSF GP-43011.     

Rheology and stability of oil-in-water nanoemulsions stabilised by anionic surfactant and gelatin 2) addition of homologous series of sugar-based co-surfactants

The oil-in-water emulsions used in silver-halide photographic coatings are stabilised with anionic surfactants and made in the presence of excess gelatin, which acts as an electrosteric stabilising agent and continuous phase viscosifier. The oil droplet sizes are close to 100 nm but the adsorbed gelatin increases the effective volume of the droplets significantly. These nanoemulsions are manufactured and coated at temperatures in excess of 40 degrees C, where gelatin adopts a random coil structure. At oil concentrations above 15% by volume, the emulsions are viscoelastic liquids with a high low-shear viscosity and strong shear-thinning. The viscosity and shear-thinning can be decreased by reducing the adsorption of gelatin, which can be achieved by addition of nonionic surfactants. This is a rheological study of the effects of adding novel, nonionic sugar-based surfactants on the rheology of photographic nanoemulsions, with additional measurements of static and dynamic surface tension. These surfactants have two sugar (gluconamide) heads and either one or two alkyl tails. Homologous series of each type of sugar surfactant were investigated over a wide range of alkyl tail length. The optimum surfactant choice for commercial applications depends not only on rheological effects but also on ease of synthesis, purification and dissolution, and of course, cost. The dynamic surface tension of the emulsion containing the anionic-nonionic surfactant mixture must also be compatible with the multilayer coating process.     

Rheology and stability of oil-in-water nanoemulsions stabilised by anionic surfactant and gelatin 1) addition of nonionic, cationic and ethoxylated-cationic co-surfactants

Oil-in-water emulsions stabilised by anionic surfactant and gelatin provide the bulk of photographic coating fluids. Their rheology is of crucial importance to the fluids' performance in coating and their concentration in drying. Gelatin complexes with non-adsorbed micelles and adsorbs to the oil-surfactant-water interface, which effects an increase in the viscosity of the continuous phase and the volume of the nano-sized oil droplets, respectively. The consequences of these interactions are high viscosity and strong shear thinning. Here, the effects on the emulsion rheology of a series of bulk, commercially available surfactants were studied. These co-surfactants were chosen so as to weaken the interactions between gelatin and the anionic surfactant and hence reduce viscosity and thinning thus enabling the emulsions to be concentrated. The co-surfactants had polar head groups of three types: simple nonionic based on polyethylenenoxide, simple cationic based on a quaternary alkyltrimethyl ammonium, and combined nonionic-cationic based on a quaternised bis-ethoxylated primary amine. This last type proved the most effective at reducing the low-shear viscosity of the emulsion and reducing the shear thinning, although, at high concentrations the polyethoxylated cationic surfactants induced flocculation and coalescence of the oil droplets.     

Host-guest interactions in a series of self-assembled As2L2Cl2 macrocycles

The reaction of AsCl3 with H2L (where L = a rigid dithiolate) results in the self-assembly of As2L2Cl2 supramolecular macrocycles. For ligands 4,4'-bis(mercaptomethyl)biphenyl (H2), 4,4'-bis(mercaptomethyl)-trans-stilbene (H2), and 1,4-dimethoxy-2,5-bis(mercaptomethyl)benzene (H2), the macrocyclic cavities of the resulting assemblies are large enough to host aromatic solvent molecules, as revealed by single crystal X-ray structures of the inclusion complexes. As2L2Cl(2) macrocycles form in solution as a mixture of diastereomers, but the diastereomers can be selectively crystallized and separated. Crystallization of syn- or anti-As(2)3(2)Cl2 can be controlled using host-guest interactions by the prudent choice of crystallization solvents. anti-As(2)3(2)Cl2 crystallizes exclusively from chloroform and benzene, while a [(syn-As(2)(2)Cl(2))(2).p-xylene] dimer crystallizes from p-xylene and a mixture of [(syn-As(2)3(2)Cl(2))(anti-As(2)3(2)Cl2) x toluene] and [(syn-As(2)3(2)Cl2)2 x toluene] dimers crystallize from toluene.     

Large Time Asymptotics for Brownian Hitting Densities of Transient Concave Curves

With appropriate regularity assumptions on the increasing concave function x=(t)<0, the hitting time density p(t) for a transient curve x=(t) by a 1-dimensional Brownian motion is shown to satisfy Here r is the probability of eventually hitting the curve and (t)=t ^–1/2(t).