Simulation of biowastes and biodegradable plastics co-digestion in semi-continuous reactors: Performances and agronomic evaluation.

The development of selective biowaste collection in most European countries provides new opportunities for the anaerobic digestion sector. In parallel, extensive development of biodegradable plastics like polylactic-acid (PLA) and polyhydroxybutyrate (PHB), which facilitates the replacement of conventional plastics, has taken place in the past decade. This study investigated anaerobic co-digestion in semi-continuous reactors of biowastes (75 % Volatil Solids) and biodegradable plastics (25 % Volatil Solids, PLA and PHB). PHB was estimated to be fully biodegraded in the reactors. By contrast, PLA accumulated in the reactor, and an average biodegradation of 47.6 ± 17.9 % was estimated during the third hydraulic retention time. Pretreatment of PLA, by thermo-alkaline hydrolysis at 70 °C, with 2.5 w/v of Ca(OH)2 for 48 h, improved the biodegradation yield of PLA to 77.5 ± 9.3 %. Finally, it was highlighted that PLA or PHB addition to the feed did not further affect the agronomic properties of the digestate.

Development of a new passive sampler based on diffusive milligel beads for copper analysis in water.

A new passive sampler was designed and characterized for the determination of free copper ion (Cu(2+)) concentration in aqueous solution. Each sampling device was composed of a set of about 30 diffusive milligel (DMG) beads. Milligel beads with incorporated cation exchange resin (Chelex) particles were synthetized using an adapted droplet-based millifluidic process. Beads were assumed to be prolate spheroids, with a diameter of 1.6 mm and an anisotropic factor of 1.4. The milligel was controlled in chemical composition of hydrogel (monomer, cross-linker, initiator and Chelex concentration) and characterized in pore size. Two types of sampling devices were developed containing 7.5% and 15% of Chelex, respectively, and 6 nm pore size. The kinetic curves obtained demonstrated the accumulation of copper in the DMG according to the process described in the literature as absorption (and/or adsorption) and release following the Fick's first law of diffusion. For their use in water monitoring, the typical physico-chemical characteristics of the samplers, i.e. the mass-transfer coefficient (k0) and the sampler-water partition coefficient (Ksw), were determined based on a static exposure design. In order to determine the copper concentration in the samplers after their exposure, a method using DMG bead digestion combined to Inductively Coupled Plasma - Atomic Emission Spectrometry (ICP-AES) analysis was developed and optimized. The DMG devices proved to be capable to absorb free copper ions from an aqueous solution, which could be accurately quantified with a mean recovery of 99% and a repeatability of 7% (mean relative uncertainty).

Saponins: a renewable and biodegradable surfactant from its microwave-assisted extraction to the synthesis of monodisperse lattices.

Synthetic surfactants are widely used in emulsion polymerization, but it is increasingly desirable to replace them with naturally derived molecules with a reduced environmental burden. This study demonstrates the use of saponins as biodegradable and renewable surfactants for emulsion polymerization. This chemical has been extracted from soapnuts by microwave assisted extraction and characterized in terms of surfactant properties prior to emulsion polymerization. The results in terms of particle size distribution and morphology control have been compared to those obtained with classical nonionic (NP40) or anionic (SDS) industrial surfactants. Microwave-extracted saponins were able to lead to latexes as stable as standard PS latex, as shown by the CMC and CCC measurements. The saponin-stabilized PS particles have been characterized in terms of particle size and distribution by Dynamic Light Scattering and Asymmetrical Flow Field Flow Fractionation. Monomodal and monodispersed particles ranging from 250 to 480 nm in terms of diameter with a particle size distribution below 1.03 have been synthesized.

Solid composite electrodes for DNA enrichment and detection.

New plastic composite electrodes with appliance in medical diagnostic are described. The new electrode material offers the possibility of specific electrical enrichment and electrochemical analysis of nucleic acid sequences. To facilitate selective enrichment of target nucleic acids, specific probe oligonucleotides were attached covalently to free carboxyl groups of conducting polycarbonate/carbon fiber electrodes. Complementary oligonucleotides were enriched from analyte solutions by electric field supported methods. The analysis of the PCR product shows the efficiency and selectivity of the electrical enrichment. We have also shown that inexpensive and robust solid electrodes made of polycarbonate and conductive carbon powder are suitable for electrochemical examination of nucleic acids. The combination of electrochemical enrichment of DNA and subsequent electrochemical detection is a promising approach towards an inexpensive molecular diagnosis kit.

Development of a molecular diagnosis assay based on electrohybridization at plastic electrodes and subsequent PCR.

Technologies enabling specific recognition of medically relevant nucleic acid sequences will play a pivotal role in future medical diagnosis. Whereas many approaches to molecular diagnosis systems include DNA microarrays on chips and fluorometric detection, the basis of our approach is the use of inexpensive components like plastic or metal thin film electrodes with low multiplexing and an electrochemical detection unit. To increase the sensitivity, PCR can be used as an intermediate step. For selective enrichment, specific nucleic acid probes were covalently attached at their 5'-ends to conducting polycarbonate/carbon fiber electrodes. Complementary oligonucleotides were enriched at the electrodes by cyclic inversion of an electrochemical potential, transferred into a PCR vial and thermally or electrochemically desorbed. The analysis of the PCR product shows the efficiency and selectivity of the electrochemical enrichment. Hybridization of DNA was shown by electrochemical methods, in this work especially by differential pulse voltammetry (DPV) using the single strand specific hybridization redox indicator osmium(VIII)-tetroxide, and potentiometric stripping analysis (PSA). This combination of experimental methods is the basis for a molecular diagnosis system including a disposable nucleic acid modified working electrode for specific enrichment, detection and quantification, and an optional capillary PCR module for fast amplification.

Delay of type I diabetes in high risk, first degree relatives by parenteral antigen administration: the Schwabing Insulin Prophylaxis Pilot Trial.

The Schwabing Insulin Prophylaxis Trial is a randomised, controlled pilot study designed to examine whether insulin therapy can delay or prevent the clinical onset of Type I diabetes in high risk first degree relatives of people with the disease. First degree relatives of patients with Type I diabetes, who were aged 4 years or more, had an islet cell antibody (ICA) value more than 20 Juvenile Diabetes Foundation Units (JDF-U), a reduced first phase insulin response (FPI) to an i.v. glucose tolerance test less than the 5th centile, and a normal oral glucose tolerance test were eligible for the trial. Between January 1989 and October 1995, 1736 relatives of patients with Type I diabetes were screened for ICA. We identified 64 cases (3.7%) with ICA values more than 20 JDF-U. Of ICA positive relatives, 17 (27%) had a low FPI and were eligible for enrolment. Of these 14 agreed to participate, of whom 7 were randomised to the treatment group and 7 to the control group. In the treatment group, human insulin was administered i.v. by continuous infusion for 7 days, followed by daily s. c. injections for 6 months. Intravenous insulin infusions were repeated every 12 months. In the treatment group 3 of the 7 individuals (follow-up from time of eligibility: 2.3 to 7.1 years) and in the control group 6 of the 7 untreated individuals (1.7 to 7.1 years) developed clinical diabetes. Life table analysis showed that clinical onset of Type I diabetes was delayed in insulin-treated subjects compared with control subjects (means+/-SEM diabetes-free survival: 5.0+/-0.9 years vs 2.3+/-0.7 years, p < 0.03). Insulin levels after i.v. glucose increased in the first year of intervention therapy. Titres of ICA, and antibodies to glutamic acid decarboxylase, and tyrosine phosphatase-like protein IA2 remained unchanged. These data suggest that insulin prophylaxis can delay the onset of overt diabetes in high risk relatives. This is encouraging in view of 1) the continuing American Diabetes Prevention Trial, which is currently testing the effect of parenteral insulin in a large nation-wide study and 2) the initiation of pilot trials to determine whether new antigen-specific intervention is more effective in delaying the clinical onset of Type I diabetes.