Possibilities and pitfalls in analyzing (upgraded) pyrolysis oil by size exclusion chromatography (SEC)

The applicability of size exclusion chromatography (SEC) to analyze (upgraded) pyrolysis oil samples has been studied using model compounds, pyrolysis oils and hydrodeoxygenated pyrolysis oils. The assumptions needed for the conversion of the chromatogram to the M_w-distribution were validated. It was shown that the conversion of elution volume to molecular weight (based on polystyrene calibration curves) can introduce substantial errors in the prediction of the molecular weight. The conversion of RID response to W(log M) (as plotted on the y-axis of the M_w-distribution) is based on the assumption of a compound independent RID response factor and linear response to concentration. While the latter was shown to be true within the concentration range studied, the former was not true: the RID response factor depends on the type of (upgraded) pyrolysis oil. It was shown that within a single pyrolysis oil sample, the RID response for the low molecular weight fraction was a factor 3 lower than the high molecular weight fraction. Furthermore long term column fouling can influence SEC results that cannot be corrected with regular polystyrene recalibrations.Based on the results we recommend SEC not to be used as a quantitative method for characterization (upgraded) pyrolysis oil samples, but as a tool to compare (upgraded) pyrolysis oil samples, preferably prepared using incremental operating conditions and expected to have similar molecular composition. This work has further shown that (i) the ∫UVDdv/∫RIDdv ratio can be used as an indication of the sum of the relative aromaticity and conjugated double bond content for (upgraded) pyrolysis oil, and (ii) the negative peak area appearing in the low molecular weight part of the chromatogram can be used to estimate the water content of (upgraded) oil samples.     

Formation of molecular monolayers on TiO2 surfaces: a surface analogue of the Williamson ether synthesis

Strategies to modify metal oxide surfaces are important because of the increasing applications of metal oxides in catalysis, sensing, electronics, and renewable energy. Here, we report the formation of molecular monolayers on anatase nanocrystalline TiO(2) surfaces at near-ambient temperatures by a simple one-step immersion. This is achieved by an analogue of the Williamson ether synthesis, in which the hydroxyl groups of the TiO(2) surface react with iodo-alkane molecules to release HI and form a Ti-O-C surface linkage. The grafted molecules were characterized by Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) to confirm the formation of covalently bonded monolayers. Kinetic studies yielded an activation barrier of ～59 kJ/mol for the grafting reaction. Measurements of hydrolytic stability of the grafted molecules in water show that approximately half the molecules are removed within minutes to hours at temperatures of 25-100 °C with an activation energy of ～82 kJ/mol, while the remaining molecules are stable for much longer periods of time. These different stabilities are discussed in terms of the different types of Ti-O-C bonds that can form on TiO(2) surfaces.     

Part two: Analytical optimisation of a procedure for lead detection in milk by means of bismuth-modified screen-printed electrodes

This work reports the optimisation of a new analytical method for lead ion detection in milk; the electrochemical detection scheme is based on the method that was described in Part I [1]. It features the use of a disposable, environmentally friendly bismuth film electrode to replace the traditionally used (toxic) mercury one while here we report an arduous development of sample treatment so that the simple device can be applied as a screening tool in many settings. For this purpose, a milk pre-treatment procedure by means of wet digestion with HCl, HClO₄, and H₂O₂ combined with an ultrasonic treatment was developed. The detection of lead ions in treated milk was then carried out using a disposable screen-printed electrode modified with Nafion^® and an “in situ” bismuth film, with the analysis being performed in anodic stripping voltammetry mode. The analytical method developed allows the detection of milk contaminated with lead ions at a concentration of 20 μg Kg⁻¹ (legal limit) and it can be proposed as a screening method for routine analysis of lead ions in milk with the advantage of employing inexpensive and portable instrumentation. Moreover, dedicated software supported by a portable instrument introduces procedures that are essential to avoid distortion from ambient lead contamination and also makes it possible for an unskilled operator to carry out each step of the analysis.     

Unlocking the Real Potential of Black Soldier Fly (Hermetia illucens) Larvae Protein Derivatives in Pet Diets

Black soldier fly larvae (BSFL)-derived proteins are gaining popularity as sustainable pet food ingredients. According to the literature, these ingredients have strong antioxidant and antimicrobial activities. Due to the ability of BSFL protein derivatives to donate hydrogen atoms and/or electrons to counterpoise unstable molecules, they could possibly help in the prevention of osteoarthritis. During this study, the antiarthritic potential of BSFL protein derivatives was evaluated using the following assays: (1) proteinase inhibition, (2) erythrocyte membrane stability, (3) reactive oxygen species (ROS) production by activated macrophages, (4) ROS production by monocytes, and (5) cellular toxicity. Additionally, the glucosamine content of these ingredients was also evaluated. Chicken meal is commonly used in pet food formulations and was used as an industrial benchmark. The results obtained during this study demonstrated the strong antiarthritic potential of BSFL protein derivatives. We found that BSFL protein derivatives are not only useful in preventing the development of arthritis but could also help to cure it due to the presence of glucosamine. We also found that chicken meal could contribute to the development of arthritis by increasing ROS production by monocytes.     

Easy interpretation of optical two-dimensional correlation spectra

We demonstrate that the value of the underlying frequency-frequency correlation function can be retrieved from a two-dimensional optical correlation spectrum through a simple relationship. The proposed method yields both intuitive clues and a quantitative measure of the dynamics of the system. The technique is applied to studying the effects of temperature and phase changes on liquid-glass solvent dynamics.     

Unified Green's function retrieval by cross correlation

It has been shown by many authors that the cross correlation of two recordings of a diffuse wave field at different receivers yields the Green's function between these receivers. Recently the theory has been extended for situations where time-reversal invariance does not hold (e.g., in attenuating media) and where source-receiver reciprocity breaks down (in moving fluids). Here we present a unified theory for Green's function retrieval that captures all these situations and, because of the unified form, readily extends to more complex situations, such as electrokinetic Green's function retrieval in poroelastic or piezoelectric media. The unified theory has a wide range of applications in "remote sensing without a source."     

Gd‐TEMDO: Design,Synthesis, and MRI Application

A simple Ugi tetrazole multicomponent reaction allows the synthesis of a novel macrocyclic cyclen derivative with four appendant tetrazole arms in just two steps in excellent yields. This ligand, called TEMDO, turns out to have a high complexation affinity with lanthanoid metals. Here we describe the design, synthesis, solid‐state structure, binding constant, and some MRI applications of the Gd‐TEMDO complex as the first example of a congeneric family of oligo‐amino tetrazoles.     

Lead tartrate from X‐ray powder diffraction data

The structure of lead tartrate, Pb²⁺·C₄H₄O₆^2?, has been solved from X‐ray powder diffraction data. The cation exhibits ninefold coordination and the tartrate groups are linked through Pb?O contacts to form a three‐dimensional network.     

5,5‐Dimethyl‐2‐[6‐methyl‐2‐(methylsulfanyl)pyrimidin‐4‐yloxy]‐1,3,2‐dioxaphosphorinane‐2‐thione

The title compound, C₁₁H₁₇N₂O₃PS₂, is a cyclic thio­phos­phoryl pyrimidine derivative exhibiting insecticidal properties. The crystal structure determination gives evidence for the presence of the thione isomer of the compound. The pyrimidine nucleus is planar and its substituents have small deviations from the least‐squares plane. The dioxaphos­phorinane ring adopts a chair conformation. The lack of classical hydrogen bonds and the weak intermolecular interactions lead to a `loose' packing characterized by channels in the structure.