Preparation and application of zeolite/ceramic microfiltration membranes for treatment of oil contaminated water

NaA zeolite microfiltration (MF) membranes were prepared on α-Al₂O₃ tube by in situ hydrothermal synthesis method and investigated for water separation and recovery from oily water. NaA/α-Al₂O₃ MF membranes with average inter-particle pore sizes of 1.2 μm, 0.4 μm and 0.2 μm were prepared. The membranes were characterized by scanning electron microscope (SEM) and the inter-particle pore size distribution (PSD) was determined by gas bubble pressure method. Membranes with pore sizes of 1.2 μm (NaA1) and 0.4 μm (NaA2) were used to treat an oil-in-water emulsion containing 100 mg/L oil. Better than 99% oil rejection was obtained and water containing less than 1 mg/L oil was produced at 85 L m⁻² h⁻¹ by NaA1 at a membrane pressure of 50 kPa. Consistent membrane performance was maintained by a regeneration regime consisting of frequent backwash with hot water and alkali solution.     

Separation and determination of metal cations in milk and dairy products by CE

To prevent casein adsorption and improve between-run repeatability, a CE procedure is developed for cation analysis in milk using a modified imidazole/alpha-hydroxyisobutyric acid (HIBA) BGE system to operate at pH 6 to match the pH of milk and elevate imidazole concentration to enhance its buffer action. The procedure is shown to produce a fast, economic and efficient method for cation separation in milk with only simple dilution. Upon direct hydrodynamic injection of diluted milk sample at 8 cm for 30 s in an uncoated column with a BGE consisting of 10 mM imidazole, 10 mM HIBA and 10% methanol at pH 6.0 under +18 kV, baseline separation was achieved for K(+), Na(+), Ca(2+), Mg(2+), Mn(2+), Cd(2+), Co(2+), Ni(2+)and Zn(2+). Agreeable results at 95% confidence level were obtained using CE and inductively coupled plasma-atomic emission spectrometry (ICP-AES) for milk samples after protein removal. Baseline-resolved peaks for essential minerals were obtained for fresh and non-refrigerated reconstituted milks. Long-term stability was demonstrated by repeated determinations without rinsing and improvement in repeatability was shown by rinsing with 60 mM SDS in BGE. Information on metal speciation useful for nutritional assessment was obtained from CE to complement the ICP methods.     

Quaternionic Numerical Range and Real Subspaces

Let W(A) be the numerical range of an n × n quaternionic matrix A and V a real subspace of the skew field of real quaternions. In this note the authors consider the relation among the shape of W(A), the convexity of V∩W(A): and the validity of the equality V∩W(A) = W_v(A), where W_v (A) is the orthogonal projection of W(A) into V.     

Infinite-Horizon Stochastic Differential Games with Branching Payoffs

In this paper, we consider infinite-horizon stochastic differential games with an autonomous structure and steady branching payoffs. While the introduction of additional stochastic elements via branching payoffs offers a fruitful alternative to modeling game situations under uncertainty, the solution to such a problem is not known. A theorem on the characterization of a Nash equilibrium solution for this kind of games is presented. An application in renewable resource extraction is provided to illustrate the solution mechanism.     

Peptide Amphiphile Mediated Co-assembly for Nanoplasmonic Sensing

Aromatic interactions are commonly involved in the assembly of naturally occurring building blocks, and these interactions can be replicated in an artificial setting to produce functional materials. Here we describe a colorimetric biosensor using co-assembly experiments with plasmonic gold and surfactant-like peptides (SLPs) spanning a wide range of aromatic residues, polar stretches, and interfacial affinities. The SLPs programmed in DDD−(ZZ)_x−FFPC self-assemble into higher-order structures in response to a protease and subsequently modulate the colloidal dispersity of gold leading to a colorimetric readout. Results show the strong aggregation propensity of the FFPC tail without polar DDD head. The SLPs were specific to the target protease, i.e., M^pro, a biomarker for SARS-CoV-2. This system is a simple and visual tool that senses M^pro in phosphate buffer, exhaled breath condensate, and saliva with detection limits of 15.7, 20.8, and 26.1 nM, respectively. These results may have value in designing other protease testing methods.     

Anisotropic fluctuations in ordered copolymer phases

The random phase approximation is reformulated to investigate the anisotropic fluctuations about an ordered polymer phase. This very general method is applied to the lamellar phase of block copolymers. The calculated anisotropic scattering intensity captures the main features observed experimentally including the secondary peaks due to fluctuations with hexagonal symmetry. We also determined the limits of metastability of the lamellar phase as well as the bending and elastic moduli of the lamellae.     

Synthesis,Redox and Optical Properties of Low‐Bandgap Platinum(II) Polyynes with 9‐Dicyanomethylene‐Substituted Fluorene Acceptors

In view of the strong electron‐withdrawing nature of the cyano substituent, a blue donor/acceptor‐type organometallic polymer (trans‐[—Pt(PBu₃)₂—C≡C—R—C≡C—]_n (R = 9‐dicyanomethylenefluorene‐2,7‐diyl)) was prepared in good yield by CuI‐catalyzed polymerization involving the dehydrohalogenating coupling of trans‐[Pt(PBu₃)₂Cl₂] and H—C≡C—R—C≡C—H. The thermal, redox and photoconducting properties of the polymer are reported. Electronic absorption studies indicate that it has a bandgap of 1.58 eV which is the lowest among any of the metal polyyne polymers reported in the literature. The derivatization of the polymer backbone with electron deficient dicyano‐substituted electron acceptor in the side chain is found to be effective to tune the bandgap of this class of materials while maintaining their solubility and processability.