Ferrofluid Impregnation Efficiency and Its Spatial Variability in Natural and Synthetic Porous Media: Implications for Magnetic Pore Fabric Studies

Transport in Porous Media - Magnetic pore fabrics (MPF) are an efficient way to characterize pore space anisotropy, i.e., the average pore shape and orientation. They are determined by impregnating...     

Co-doped ZnO nanoparticles synthesized by an adapted sol–gel method: effects on the structural,optical, photocatalytic and antibacterial properties

Pure and Co-doped ZnO nanoparticles were synthesized with different cobalt levels (1–10 mol%) via adapted sol–gel method using water as solvent and characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy and photoacoustic absorption spectroscopy. The results showed that all the samples have hexagonal wurtzite structure, with no evidence of any secondary phases until 10 mol% of the dopant. The average crystallite size of the samples was in the range of 25–50 nm, do not showing significant differences with the increase of the dopant level. However, the band gap energy of the nanoparticles decreases from 2.98 eV (pure ZnO) to 1.95 eV (10 mol% of Co). The photocatalytic activity of the samples was evaluated on the removal of methylene blue under visible light irradiation, which revealed an efficiency reduction by Co-doping ZnO. The antibacterial property was carried out indicating activity of the prepared samples against gram-positive bacteria.     

Synthesis and Electronic Properties of 1,2‐Hemisquarimines and Their Encapsulation in a Cucurbit[7]uril Host

The synthesis of a new class of robust squaraine dyes, colloquially named 1,2‐hemisquarimines (1,2‐HSQiMs), through the microwave‐assisted condensation of aniline derivatives with the 1,2‐squaraine core is reported. In CH₃CN, 1,2‐HSQiMs show a broad absorption band with a high extinction coefficient and a maximum at around λ=530 nm, as well as an emission band centered at about λ=574 nm, that are pH dependent. Protonation of the imine nitrogen causes a redshift of both absorption and emission maxima, with a concomitant increase in the lifetime of the emitting excited state. Encapsulation of the chromophore into a cucurbit[7]uril host revealed fluorescence enhancement and increased photostability in water. The redox characteristics of 1,2‐HSQiMs indicate that charge injection into TiO₂ is possible; this opens up promising perspectives for their use as photosensitizers for solar energy conversion.     

Access to β‐Lactams by Enantioselective Palladium(0)‐Catalyzed C(sp3)H Alkylation

β‐Lactams are very important structural motifs because of their broad biological activities as well as their propensity to engage in ring‐opening reactions. Transition‐metal‐catalyzed C? H functionalizations have emerged as strategy enabling yet uncommon highly efficient disconnections. In contrast to the significant progress of Pd⁰‐catalyzed C? H functionalization for aryl–aryl couplings, related reactions involving the formation of saturated C(sp³)? C(sp³) bonds are elusive. Reported here is an asymmetric C? H functionalization approach to β‐lactams using readily accessible chloroacetamide substrates. Important aspects of this transformation are challenging C(sp³)? C(sp³) and strain‐building reductive eliminations to for the four‐membered ring. In general, the β‐lactams are formed in excellent yields and enantioselectivities using a bulky taddol phosphoramidite ligand in combination with adamantyl carboxylic acid as cocatalyst.     

XAS analysis of iron and palladium bonded to a polysaccharide produced anaerobically by a strain of Klebsiella oxytoca

Klebsiella oxytoca BAS‐10 ferments citrate to acetic acid and CO₂, and secretes a specific exopolysaccharide (EPS), which is able to bind different metallic species. These biomaterials may be used for different biotechnological purposes, including applications as innovative green biogenerated catalysts. In production of biogenerated Pd species, the Fe(III) as ferric citrate is added to anaerobic culture of K. oxytoca BAS‐10, in the presence of palladium species, to increase the EPS secretion and improve Pd‐EPS yield. In this process, bi‐metallic (FePd‐EPS) biomaterials were produced for the first time. The morphology of bi‐metallic EPS, and the chemical state of the two metals in the FePd‐EPS, are investigated by transmission electron microscopy, Fourier transform infra‐red spectroscopy, micro‐X‐ray fluorescence, and X‐ray absorption spectroscopy methods (XANES and EXAFS), and compared with mono‐metallic Pd‐EPS and Fe‐EPS complexes. Iron in FePd‐EPS is in the mineralized form of iron oxides/hydroxides, predominantly in the form of Fe³⁺, with a small amount of Fe²⁺ in the structure, most probably a mixture of different nano‐crystalline iron oxides and hydroxides, as in mono‐metallic Fe‐EPS. Palladium is found as Pd(0) in the form of metallic nanoparticles with face‐centred cubic structure in both bi‐metallic (FePd‐EPS) and mono‐metallic (Pd‐EPS) species. In bi‐metallic species, Pd and Fe nanoparticles agglomerate in larger clusters, but they remain spatially separated. The catalytic ability of bi‐metallic species (FePd‐EPS) in a hydrodechlorination reaction is improved in comparison with mono‐metallic Pd‐EPS.     

A new fluorescent double-cavity calix[4]arene: synthesis and complexation studies toward nitroanilines

A novel bicyclic calix[4]arene (4) molecular receptor has been synthesized, and its sensory abilities toward noxious aromatic nitroamines evaluated in apolar media. Molecular host–guest interactions examined through fluorescence and ¹H NMR spectroscopies showed the formation of 1:1 type endo-inclusion complexes with all the nitroaniline guests. The potential of 4 as a chemical sensor is established.     

Application of data fusion techniques to direct geographical traceability indicators

A hierarchical data fusion approach has been developed proposing multivariate curve resolution (MCR) as a variable reduction tool.     

An Investigation by 31P-N.M.R. Spectroscopy into the Occurrence of High Energy Phosphates in Helminths (Worms)

Abstract

N-Phosphorylated guanidines (phosphagens,I), found in living tissue, act as high energy phosphate regulators of adenosine triphosphate. Vertebrates possess phosphocreatine (Ia) as their sole phosphagen whereas in invertebrates phosphoarginine (Ib) predominates. However, in certain non-parasitic helminths (Annelida), a novel class of phosphagens exists based on a phosphodiester structure (Ic) exemplified by phospholombricine (R′= CH₂ CH(NH₂)CO₂H).     

The BIOREMA project—part 1: Towards international comparability for biofuel analysis

There is an increasing demand to accurately measure the quality of biofuel products (e.g. biodiesel and bio-ethanol). This demand is driven in Europe by directives promoting the use of renewable sources of energy and worldwide by national and international legislation setting out quality requirements for these fuels. Until now, there has been no international consensus on the minimum technical specifications to ensure biofuel quality. Furthermore, it is unclear which reference materials and measurement techniques are needed to provide the quality assurance and quality control framework to underpin these legislative requirements. As part of the European Commission’s 7th Framework Programme, the BIOREMA project (REference MAterials for BIOfuel specifications) demonstrated the feasibility of preparing biodiesel and bio-ethanol reference materials with reference values traceable to the international system of units for a range of parameters at levels relevant to technical specifications. However, the project concluded also that further research is needed to improve the current measurement capabilities for some parameters. Within the BIOREMA project, two global interlaboratory comparisons were carried out, using the biodiesel and bio-ethanol test materials prepared during the feasibility stage of the project, as well as two biodiesel standard reference materials from the National Institute of Standards and Technology (NIST, USA). The exercises showed that the measurement capabilities of the field laboratories were in many cases satisfactory, whereas for other laboratories the availability and regular use of certified reference materials would likely enhance the measurement capabilities for many of the parameters studied. A general overview of the BIOREMA project is presented in this paper. The details of the production of the two types of BIOREMA reference materials, and the results of the interlaboratory comparison for the bio-ethanol and biodiesel study materials, are discussed in parts 2 and 3 of this series of papers.