James M. Hook

An investigation into the reactions of biochar in soil

Interactions between biochar, soil, microbes, and plant roots may occur within a short period of time after application to the soil. The extent, rates, and implications of these interactions, however, are far from understood. This review describes the properties of biochars and suggests possible reactions that may occur after the addition of biochars to soil. These include dissolution-precipitation, adsorption-desorption, acid-base, and redox reactions. Attention is given to reactions occurring within pores, and to interactions with roots, microorganisms, and soil fauna. Examination of biochars (from chicken litter, greenwaste, and paper mill sludges) weathered for 1 and 2 years in an Australian Ferrosol provides evidence for some of the mechanisms described in this review and offers an insight to reactions at a molecular scale. These interactions are biochar- and site-specific. Therefore, suitable experimental trials—combining biochar types and different pedoclimatic conditions—are needed to determine the extent to which these reactions influence the potential of biochar as a soil amendment and tool for carbon sequestration.

Shifting paradigms: development of high-efficiency biochar fertilizers based on nano-structures and soluble components

Many biochars have a complex carbon lattice structure with aromatic and aliphatic domains, acidic and basic groups, vacancies, metallic and non-metallic elements, and free radicals. Biochars also have separate mineral oxide, silicate and salt phases, and small and large organic molecules. In the rhizosphere, such constituents can be involved in chemical and biological processes along a soil–microbe–plant continuum, including nutrient cycling, metal chelation and stabilization, redox reactions, and free radical scavenging. It is hypothesized that the greater the amount of these nanoparticles and dissolved components, the greater will be plant and microbial responses. We provide suggestions for developing low-dose, high-efficiency biochar–nanoparticle composites, as well as initial field trial results and detailed characterization of such a biochar–fertilizer composite, to highlight the potential of such biochars.

Survival from high-grade localised extremity osteosarcoma: combined results and prognostic factors from three European Osteosarcoma Intergroup randomised controlled trials

BACKGROUND Neoadjuvant chemotherapy improves outcome in osteosarcoma. Determination of optimum regimens for survival, toxicity and prognostic factors requires randomised controlled trials to be conducted. PATIENTS AND METHODS Between 1983 and 2002, the European Osteosarcoma Intergroup recruited 1067 patients with localised extremity osteosarcoma to three randomised controlled trials. Standard treatment in each was doxorubicin 75 mg/m(2) and cisplatin 100 mg/m(2). Comparators were addition of methotrexate (BO02/80831), a multidrug regimen (BO03/80861) and a dose-intense schedule (BO06/80931). Standard survival analysis methods were used to identify prognostic factors, temporal and other influences on outcome. RESULTS Five- and 10-year survival were 56% (95% confidence interval 53% to 59%) and 52%, respectively (49% to 55%), with no difference between trials or treatment arms. Median follow-up was 9.4 years. Age range was 3-40 years (median 15). Limb salvage was achieved in 69%. Five hundred and thirty-three patients received the standard arm, 79% completing treatment. Good histological response to preoperative chemotherapy, distal tumour location (all sites other than proximal humerus/femur) and female gender were associated with improved survival. CONCLUSIONS Localised osteosarcoma will be cured in 50% of patients with cisplatin and doxorubicin. Large randomised trials can be conducted in this rare cancer. Failure to improve survival over 20 years argues for concerted collaborative international efforts to identify and rapidly test new treatments.

An investigation into the supramolecular structure, solubility, stability and antioxidant activity of rutin/cyclodextrin inclusion complex

The formation of supramolecular inclusion complexes between rutin and four cyclodextrins, namely β-cyclodextrin (β-CD), (2-hydroxypropyl)-α-cyclodextrin (HP-α-CD), (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD) and (2-hydroxypropyl)-γ-cyclodextrin (HP-γ-CD), and the effects of the complexation on the stability and antioxidant activity of rutin were investigated. Results from phase-solubility studies showed that rutin formed 1:1 stoichiometric inclusion complexes with HP-α-CD, β-CD, HP-β-CD and HP-γ-CD; the complexes formed with HP-γ-CD and HP-β-CD had the greatest stability constants, followed by β-CD and HP-α-CD. Thermodynamic studies demonstrate that the inclusion of rutin into HP-β-CD was an exothermic process which occurred spontaneously. Two-dimensional rotating-frame nuclear Overhauser effect spectroscopy (2D ROESY) (1)H NMR analyses show that the A ring of rutin was the part of the molecule that most likely inserted into the cavity of HP-β-CD, thus forming a supramolecular inclusion complex. Formation of such an inclusion complex conferred moderate degrees of protection to rutin from degradation by heat and UV radiation during storage, and significantly enhanced its antioxidant capacity as determined by three different procedures.

An oxidative carbon–carbon bond-forming reaction proceeds via an isolable iminium ion

The mechanism of our previously reported DDQ-mediated oxidative C–C bond-forming reaction is investigated. We are able to trap and characterize an iminium ion intermediate with X-ray crystallography, elemental analysis, and solid-state NMR spectroscopy; to our knowledge this is the first time this putative intermediate ion has been directly observed in such cross-dehydrogenative couplings (CDCs). The intermediate can be reacted with a range of nucleo-philes, including a malonate that is not amenable to a one-pot reaction protocol.

Dolichol is the major lipid component of human substantia nigra neuromelanin.

Neuromelanin is a dark brown pigment present at high concentrations in dopaminergic neurones of the human substantia nigra (SN). Early electron microscopic examinations of neuromelanin fine structure revealed a significant neutral lipid component; however, the identity of this lipid has remained unknown. Here we show that the lipid component of neuromelanin pigment derived from human SN is the polyisoprenoid dolichol. Established methods were used to isolate the pigment from the SN of 32 brains and the lipid fraction was recovered in high purity and yield. Using reversed‐phase HPLC, atmospheric pressure chemical ionization mass spectrometry, and 1H‐ and 13C‐NMR techniques, we showed that the neuromelanin dolichol contained 17–23 isoprenoid units. Dolichol accounted for 14% of the mass of neuromelanin pigment; low levels of other hydrophobic compounds were detected (e.g. ubiquinone‐10, α‐tocopherol and cholesterol together accounted for < 0.5% of the neuromelanin lipid mass). This is the first time that dolichol has been identified in such a physiological setting and significantly advances our understanding of neuromelanin pigment structure and biosynthetic pathways. Furthermore, these studies identify a potential novel role for the isoprenoid pathway in the regulation of neuromelanin function and neurodegeneration within the SN.

PHENYLTIN DIETHYLDITHIOCARBAMATES: SOLID STATE AND SOLUTION STRUCTURES AND IN VITRO ANTI-TUMOUR ACTIVITY

Solution and cross-polarized magic-angle spinning (CP-MAS) solid state NMR data ( 1 3 C and 1 1 Sn) for a series of phenyltin diethyldithiocarbamate compounds and the crystal structures of a tetragonal modification of [Ph2Sn(dedtc)2] and of [Ph3Sn(dedtc)] are reported. A strong correspondence between the solution and solid state structures of these compounds has been discovered. The phenyltin diethyldithiocarbamate compounds have been evaluated for activity against the L1210 mouse leukemia cell line. They have been found to be as least as active as cisplatin, but there is no obvious structure-activity correlation.

Functionalizing Biodegradable Dextran Scaffolds Using Living Radical Polymerization: New Versatile Nanoparticles for the Delivery of Therapeutic Molecules

Conferring biodegradability to nanoparticles is vitally important when nanomedicine applications are being targeted, as this prevents potential problems with bioaccumulation of byproducts after delivery. In this work, dextran has been modified (and rendered hydrophobic) by partial acetalation. A solid state NMR method was first developed to fully characterize the acetalated polymers. In a subsequent synthetic step, RAFT functionality was attached via residual unmodified hydroxyl groups. The RAFT groups were then used in a living free radical polymerization reaction to control the growth of hydrophilic PEG-methacrylate chains, thereby generating amphiphilic comblike polymers. The amphiphilic polymers were then self-assembled in water to form various morphologies, including small vesicles, wormlike rods, and micellar structures, with PEG at the periphery acting as a nonfouling biocompatible polymer layer. The acetalated dextran nanoparticles were designed for potential doxorubicin (DOX) delivery application based on the premise that in the cell compartments (endosome, lysozome) the acetalated dextran would hydrolyze, destroying the nanoparticle structure, releasing the encapsulated DOX. In-vitro studies confirmed minimal cytotoxicity of the (unloaded) nanoparticles, even after 3 days, proving that the hydrolysis products from the acetal groups (methanol and acetone) had no observable cytotoxic effect. An intriguing initial result is reported that in vitro studies of DOX-loaded dextran-nanoparticles (compared to free DOX) revealed an increased differential toxicity toward a cancer cell line when compared to a normal cell line. Efficient accumulation of DOX in a human neuroblastoma cell line (SY-5Y) was confirmed by both confocal microscopy and flow cytometry measurements. Furthermore, the time dependent release of DOX was monitored using fluorescence lifetime imaging microscopy (FLIM) in SY-5Y live cells. FLIM revealed bimodal lifetime distributions, showing the accumulation of both DOX-loaded dextran-nanoparticles and subsequent release of DOX in the living cells. From FLIM data analysis, the amount of DOX released in SY-5Y cells was found to increase from 35% to 55% when the incubation time increased from 3 h to 24 h.

A Simple and Efficient Synthesis of Ethyl and Methyl Glyoxylate

Abstract Ethyl and methyl glyoxylate are both prepared in high yields from an exchange reaction between the appropriate alkyl dialkoxyacetate and glyoxylic acid, followed by reaction with phosphorus pentoxide.

Ionic liquids: just Molten salts after all?

While there has been much effort in recent years to characterise ionic liquids in terms of parameters that are well described for molecular solvents, using these to explain reaction outcomes remains problematic. Herein we propose that many reaction outcomes in ionic liquids may be explained by considering the electrostatic interactions present in the solution; that is, by recognising that ionic liquids are salts. This is supported by evidence in the literature, along with studies presented here.