Developing Multicompartment Biopolymer Hydrogel Beads for Tandem Chemoenzymatic One-Pot Process

Pauly J, Gröger H, Patel A. Developing Multicompartment Biopolymer Hydrogel Beads for Tandem Chemoenzymatic One-Pot Process. Catalysts. 2019;9(6): 547.Chemoenzymatic processes have been gaining interest to implement sustainable reaction steps or even create new synthetic routes. In this study, we combined Grubbs' second-generation catalyst with pig liver esterase and conducted a chemoenzymatic one-pot process in a tandem mode. To address sustainability, we encapsulated the catalysts in biopolymer hydrogel beads and conducted the reaction cascade in an aqueous medium. Unfortunately, conducting the process in tandem led to increased side product formation. We then created core-shell beads with catalysts located in different compartments, which notably enhanced the selectivity towards the desired product compared to homogeneously distributing both catalysts within the matrix. Finally, we designed a specific large-sized bead with a diameter of 13.5 mm to increase the diffusion route of the Grubbs' catalyst-containing shell. This design forced the ring-closing metathesis to occur first before the substrate could diffuse into the pig liver esterase-containing core, thus enhancing the selectivity to 75%. This study contributes to addressing reaction-related issues by designing specific immobilisates for chemoenzymatic processes

Screening of liquid media and fermentation of an endophytic Beauveria bassiana strain in a bioreactor

Lohse R, Jakobs-Schönwandt D, Patel A. Screening of liquid media and fermentation of an endophytic Beauveria bassiana strain in a bioreactor. AMB Express. 2014;4(1): 47.A novel approach for biological control of insect pests could be the use of the endophytic entomopathogenic Beauveria bassiana isolate ATP-02. For the utilization of the endophyte as a commercial biocontrol agent, the fungus has to be mass-produced. B. bassiana was raised in shake flask cultures to produce high concentrations of total spores (TS), which include blastospores (BS) and submerged conidiospores (SCS). The highest concentration of 1.33×109 TS/mL and the highest yield of 5.32×1010 TS/g sucrose was obtained in the TKI broth with 5% sugar beet molasses which consists of 50% sucrose as a carbon source. In spite of the lower sugar concentration (2.5%) the amount of TS could be increased up to 11-times in contrast to the cultivation with 5% sucrose. The scale-up to a 2 L stirred tank reactor was carried out at 25°C, 200–600 rpm and 1 vvm at pH 5.5. A TS yield of 5.2×1010 TS/g sucrose corresponding to a SCS yield of 0.2×1010 SCS/g sucrose was obtained after 216 h. With regards to the culture medium the cost of 1012 TS amounts to 0.24 €. Plutella xylostella larvae, which were fed with oilseed rape leaves treated with spores from fermentation resulted in 77 ± 5% mortality. Moreover, spores from submerged cultivation were able to colonize oilseed rape leaves via leaf application. This is the first report of fermentation of an endophytic B. bassiana strain in a low-cost culture medium to very high yields of TS

An investigation into the use of additive manufacture for the production of metallic bipolar plates for polymer electrolyte fuel cell stacks

The bipolar plate is of critical importance to the efficient and long lasting operation of a polymer electrolyte fuel cell (PEMFC) stack. With advances in membrane electrode assembly design, greater attention has been focused on the bipolar plate and the important role it plays. Although carbon composite plates are a likely candidate for the mass introduction of fuel cells, it is metallic plates made from thin strip materials which could deliver significant advantages in terms of part cost, electrical performance and size. However, there are some disadvantages. Firstly, interfacial stability of the metal interconnect is difficult to achieve. Secondly, and the issue addressed here, is the difficultly and cost in developing new plate designs when there are very significant tooling costs associated with manufacture. The use of selective laser melting (SLM: an additive manufacturing technique) was explored to produce metallic bipolar plates for PEMFC as a route to inexpensively test several plate designs without committing to tooling. Crucial to this was proving that, electrically, bipolar plates fabricated by SLM behave similarly to those produced by conventional manufacturing techniques. This research presents the development of a small stack to compare the short term performance of metallic plates made by machining against those made by SLM. Experimental results demonstrate that the cell performance in this case was unaffected by the manufacturing method used and it is therefore concluded that additive manufacturing could be a very useful tool to aid the rapid development of metallic bipolar plate designs

The use of additive manufacture for metallic bipolar plates in polymer electrolyte fuel cell stacks

The bipolar plate is of critical importance to the efficient and long lasting operation of a polymer electrolyte fuel cell (PEMFC) stack. With advances in membrane electrode assembly (MEA) design greater attention has been focused on the bipolar plate and the important role it plays in performance and durability. Although carbon composite plates are a likely candidate for the mass introduction of fuel cells, it is metallic plates made from thin strip materials (typically 0.2 mm thick stainless strip) which could deliver significant advantages in terms of part cost, electrical performance and size. However, there are some disadvantages. Firstly, interfacial stability of the metal interconnect is difficult to achieve leading to migration of ions into the MEA and also an increase in contact resistance. Secondly, and the issue addressed here, is the difficultly and cost in developing new plate designs when there are very significant tooling costs associated with manufacture. The use of selective laser melting (SLM: an additive manufacturing technique) was explored to produce metallic bipolar plates for PEMFC as a route to inexpensively test several plate designs without committing to tooling. Crucial to this was proving that, electrically, bipolar plates fabricated by SLM behave similarly to those produced by conventional manufacturing techniques. This research presents the development of a small stack to compare the short term performance of metallic (316L stainless steel) plates made by machining against those made by SLM. Polarisation curves and impedance experiments were conducted. These demonstrate that the cell performance was unaffected by the manufacturing method used and that the pure resistive content of the impedance spectra, a proportion of which could be attributed to contact resistance between the MEA and plate, was very similar. It is concluded that additive manufacturing could be a very useful tool to aid the rapid development of metallic bipolar plate designs. However, when making direct comparisons with very space efficient designs, some challenges exist in the generation of very thin planar forms which would be most representative of sheet metal parts

Recovery of platinum group metal value via potassium iodide leaching

Platinum recovery from secondary sources such as end-of-life polymer electrolyte fuel cells (PEMFCs) via electrowinning and chemical dissolution in deoxygenated 4M potassium iodide with varying added iodine content was investigated. Previous research in this field has shown complete platinum recovery from model systems is possible, but further study was necessary to determine the process’ viability with Pt containing devices. The work presented here investigated the leach rate of platinum black deposited on an electrochemical quartz crystal microbalance (EQCM) as well as the effective recovery of Pt from untested and end-of-life polymer electrolyte membrane fuel cells. Platinum black dissolution rates were found to be dependent on added iodine content, with higher concentrations accelerating the reaction. Platinum recovery from leached materials, as determined by aqua regia digestion, was found to be 98.7% and 96.7% for untested and end-of-life PEMFCs, respectively. Results indicate higher iodine concentrations continuously improved recovery efficiency, but increasing iodine concentration above 5mM resulted in comparatively minor improvements

'Attract & Kill' - ein innovatives Konzept zur biologischen Bekämpfung von bodenlebenden Schädlingen

Soil dwelling pest species are difficult to control because of their cryptic life style and their unpredictable distribution belowground. The efficacy of biological control agents is limited, mainly because of low rhizosphere competence. Here we propose to use a strategy where pest are attracted to killing agents instead of bringing killing agents to the pest. We developed capsules emitting carbon-dioxide which are combined with an specific isolate of an entomopathogenic fungus or Neem. The principle of an attract & kill strategy takes advantage of the behaviour of soil dwelling larvae which use CO2 for locating their host plants. Components used for the production of the capsules are just contain biologically derived substances and therefore do not pose any specific problems for use in organic production systems

Balloon dilatation of the eustachian tube for obstructive eustachian tube dysfunction in adults

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: To evaluate the effects of balloon dilatation of the Eustachian tube in adults with obstructive Eustachian tube dysfunction

Alternative strategies to by-pass the plant-based Azadirachtin-A production

All parts of Neem (Azadirachta indica A. Juss) show a broad spectrum efficacy against insect pests including insecticidal, anti-feedant or insect repellent activities. Several studies have shown that plant cell cultures can produce azadirachtins. We induced more than 40 novel Neem cell lines in modified Murashige and Skoog (MS) media containing different concentrations of auxins and cytokinins. To enhance the Azadirachtin production from 1 mg/l, it was necessary to optimize the media composition separately for biomass and secondary metabolite production. In light of this complex challenge we used our novel fully automated high-throughput microbioreactor system that allows us a fast and controlled batch and fedbatch screening in 48-well microtiter plates. There is increasing evidence that plants like Azadirachta indica contain endophytes which are able to colonize internal plant tissue without causing visible disease symptoms. The estimated high species diversity of endophytes suggests a rich and almost untapped source of new secondary metabolites. We isolated more than 340 endophytes from various plant tissues and tested if they were able to produce Azadirachtin-A. Here, we present data on isolation of endophytes and induction of callus as well as first results of our microbioreactor system