Geometry and analysis of spin equations

We introduce W‐spin structures on a Riemann surface Σ and give a precise definition to the corresponding W‐spin equations for any quasi‐homogeneous polynomial W. Then we construct examples of nonzero solutions of spin equations in the presence of Ramond marked points. The main result of the paper is a compactness theorem for the moduli space of the solutions of W‐spin equations when W = W(x₁, …, x_t) is a nondegenerate, quasi‐homogeneous polynomial with fractional degrees (or weights) q_i < ½ for all i. In particular, the compactness theorem holds for the superpotentials E₆, E₇, E₈ or A_{n ? 1}, D_{n + 1} for n ≥ 3. © 2008 Wiley Periodicals, Inc.     

Supercongruences for the Catalan–Larcombe–French numbers

In this short note, we develop the Stienstra–Beukers theory of supercongruences in the setting of the Catalan–Larcombe–French sequence. We also give some applications to other sequences.     

Characterization of Mechanisms of Pesticide Retention in Soils Using the Supercritical Fluid Extraction Technique

Abstract

This research determined the relative effectiveness of supercritical fluid extraction (SFE) in extracting atrazine and its metabolites from soils which had been treated with atrazine for varying periods of time in order to characterize binding mechanisms. Aqueous methanol extraction was more effective than SFE in removing ¹⁴C atrazine residues from “aged” soils. The more polar the solvent system, the more ¹⁴C-atrazine residues were extracted. The order of polarity and extractability was aqueous methanol > SF-CO₂/5% methanol > SF-CO². Atrazine extraction efficiency using SF-CO₂, and SF-CO₂/.5% methanol decreased as samples “aged” in the field. The less than complete recovery of atrazine residues using the SFE technique could be seen as an indication that different binding mechanisms were involved in the retention of atrazine as well as its metabolites and that the binding mechanisms changed with time.     

Comparison of ED-XRF and LA-ICP-MS with the European reference method of acid digestion-ICP-MS for the measurement of metals in ambient particulate matter

A comparison study of the measurement of metals in ambient particulate matter collected on air filters, using energy-dispersive X-ray fluorescence (ED-XRF), laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) and wet chemical digestion followed by ICP-MS analysis according to the European ‘reference method’ EN14902, is presented. Whilst it is shown that the methods have a low systematic bias with respect to each other, overall they do show a high random variability, and when considered individually using regression methods, some analytes have shown bias with respect to the EN14902 method. The low systematic bias observed is not unexpected since both the ED-XRF and LA-ICP-MS methods have been calibrated using results from the EN14902 technique. The uncertainty of each analysis has been estimated and compared with the data quality objectives for uncertainty specified in the relevant European air quality legislation. This has tentatively shown that approximately 75% of the analyses using ED-XRF and LA-ICP-MS meet the requirements of the legislation. However, improvements in repeatability and calibration methods for both ED-XRF and LA-ICP-MS would be needed before these methods were truly applicable for routine use in air quality measurements of this type.     

KINETIC STUDY OF THE REACTIONS OF TRIARYLPHOSPHINES WITH α-HALO SULFONES

Abstract

Reaction of a series of triarylphosphines with α-halo-m-cyanobenzyl phenyl sulfones gives the following Hammett ρ values: (CI) ρ = ?1.84; (Br) ρ = ?3.03; (I) ρ = ?3.36.     

Protein and mRNA Delivery Enabled by Cholesteryl‐Based Biodegradable Lipidoid Nanoparticles

Developing safe and efficient delivery systems for therapeutic biomacromolecules is a long‐standing challenge. Herein, we report a newly developed combinatorial library of cholesteryl‐based disulfide bond‐containing biodegradable cationic lipidoid nanoparticles. We have identified a subset of this library which is effective for protein and mRNA delivery in vitro and in vivo. These lipidoids showed comparable transfection efficacies but much lower cytotoxicities compared to the Lpf2k in vitro. In vivo studies in adult mice demonstrated the successful delivery of genome engineering protein and mRNA molecules in the skeletal muscle (via intramuscular injection), lung and spleen (via intravenous injection), and brain (via lateral ventricle infusion).     

Protein and mRNA Delivery Enabled by Cholesteryl-Based Biodegradable Lipidoid Nanoparticles

Developing safe and efficient delivery systems for therapeutic biomacromolecules is a long-standing challenge. Herein, we report a newly developed combinatorial library of cholesteryl-based disulfide bond-containing biodegradable cationic lipidoid nanoparticles. We have identified a subset of this library which is effective for protein and mRNA delivery in vitro and in vivo. These lipidoids showed comparable transfection efficacies but much lower cytotoxicities compared to the Lpf2k in vitro. In vivo studies in adult mice demonstrated the successful delivery of genome engineering protein and mRNA molecules in the skeletal muscle (via intramuscular injection), lung and spleen (via intravenous injection), and brain (via lateral ventricle infusion).     

Activity Coefficients of Individual Ions from Titration Data

It is shown that the activity coefficients of the anions resulting from the dissociation of a weak polyprotic acid can be obtained from titration data. Activity coefficients are determined in terms of the activity coefficient of the undissociated acid. The extracted activity coefficients are also dependent on the pH scale adopted in the titration process and are considered as operational coefficients. The computational procedure uses an exact equation representing the titration curve and a nonlinear least-squares fitting procedure. As an illustration, the activity coefficients of the anions of succinic acid are determined. The method also allows study of the variation of the activity coefficients with the ionic strength in a straightforward manner.