The cyber–physical nature of biotechnology raises unprecedented security concerns. Computers can be compromised by encoding malware in DNA sequences, and biological threats can be synthesized using ...publicly available data. Trust within the biotechnology community creates vulnerabilities at the interface between cyberspace and biology. Awareness is a prerequisite to managing these risks.
We report on a novel biocompatible, highly conductive three-dimensional cathode manufactured by direct growth of flexible multiwalled carbon nanotubes on reticulated vitreous carbon (NanoWeb-RVC) for ...the improvement of microbial bioelectrosynthesis (MES). NanoWeb-RVC allows for an enhanced bacterial attachment and biofilm development within its hierarchical porous structure. 1.7 and 2.6 fold higher current density and acetate bioproduction rate normalized to total surface area were reached on NanoWeb-RVC
versus
a carbon plate control for the microbial reduction of carbon dioxide by mixed cultures. This is the first study showing better intrinsic efficiency as biocathode material of a three-dimensional electrode
versus
a flat electrode: this comparison has been made considering the total surface area of the porous electrode, and not just the projected surface area. Therefore, the improved performance is attributed to the nanostructure of the electrode and not to an increase in surface area. Unmodified reticulated vitreous carbon electrodes lacking the nanostructure were found unsuitable for MES, with no biofilm development and no acetate production detected. The high surface area to volume ratio of the macroporous RVC maximizes the available biofilm area while ensuring effective mass transfer to and from the biofilm. The nanostructure enhances the bacteria-electrode interaction and microbial extracellular electron transfer. When normalized to projected surface area, current densities and acetate production rates of 3.7 mA cm
−2
and 1.3 mM cm
−2
d
−1
, respectively, were reached, making the NanoWeb-RVC an extremely efficient material from an engineering perspective as well. These values are the highest reported for any MES system to date.
Two synthesis routes to graphene/polycaprolactone composites are introduced and the properties of the resulting composites compared. In the first method, mixtures are produced using solution ...processing of polycaprolactone and well dispersed, chemically reduced graphene oxide and in the second, an esterification reaction covalently links polycaprolactone chains to free carboxyl groups on the graphene sheets. This is achieved through the use of a stable anhydrous dimethylformamide dispersion of graphene that has been highly chemically reduced resulting in mostly peripheral ester linkages. The resulting covalently linked composites exhibit far better homogeneity and as a result, both Young’s modulus and tensile strength more than double and electrical conductivities increase by ≈14 orders of magnitude over the pristine polymer at less than 10% graphene content. In vitro cytotoxicity testing of the materials showed good biocompatibility resulting in promising materials for use as conducting substrates for the electrically stimulated growth of cells.
The ability to create 3D tissues from induced pluripotent stem cells (iPSCs) is poised to revolutionize stem cell research and regenerative medicine, including individualized, patient‐specific stem ...cell‐based treatments. There are, however, few examples of tissue engineering using iPSCs. Their culture and differentiation is predominantly planar for monolayer cell support or induction of self‐organizing embryoids (EBs) and organoids. Bioprinting iPSCs with advanced biomaterials promises to augment efforts to develop 3D tissues, ideally comprising direct‐write printing of cells for encapsulation, proliferation, and differentiation. Here, such a method, employing a clinically amenable polysaccharide‐based bioink, is described as the first example of bioprinting human iPSCs for in situ expansion and sequential differentiation. Specifically, we have extrusion printed the bioink including iPSCs, alginate (Al; 5% weight/volume w/v), carboxymethyl‐chitosan (5% w/v), and agarose (Ag; 1.5% w/v), crosslinked the bioink in calcium chloride for a stable and porous construct, proliferated the iPSCs within the construct and differentiated the same iPSCs into either EBs comprising cells of three germ lineages—endoderm, ectoderm, and mesoderm, or more homogeneous neural tissues containing functional migrating neurons and neuroglia. This defined, scalable, and versatile platform is envisaged being useful in iPSC research and translation for pharmaceuticals development and regenerative medicine.
Human tissues are generated by 3D bioprinting human induced pluripotent stem cells that proliferate and differentiate to form renewable 3D tissues. 3D tissues comprise cells of the three germ lineages—endoderm, ectoderm, and mesoderm, demonstrating the capacity to form all cells and tissues of the body, or more homogeneous neural tissues containing functional (including migrating) neurons and supporting neuroglia.
He'll weld with a mighty hand. Flash‐welded polyaniline nanofiber actuators demonstrate unprecedented reversible, rapid actuation upon doping. An intense flash of light creates an asymmetric ...structure (see figure) with a thin dense layer on top of a thick porous nanofibrillar layer. On exposure to camphor sulfonic acid the asymmetric film curls more than 720°.
Efficient lower hybrid current drive (LHCD) is demonstrated at densities up to nover ¯_{e}≈1.5×10^{20} m^{-3} in diverted plasmas on the Alcator C-Mod tokamak by operating at increased plasma ...current-and therefore reduced Greenwald density fraction. This density exceeds the nominal "LH density limit" at nover ¯_{e}≈1.0×10^{20} m^{-3} reported previously, above which an anomalous loss of current drive efficiency was observed. The recovery of current drive efficiency to a level consistent with engineering scalings is correlated with a reduction in density shoulders and turbulence levels in the far scrape-off layer. Concurrently, rf wave interaction with the edge and/or scrape-off-layer plasma is reduced, as indicated by a minimal broadening of the wave frequency spectrum measured at the plasma edge. These results have important implications for sustaining steady-state tokamak operation and indicate a pathway forward for implementing efficient LHCD in a reactor.
The creation of composite structures is a commonly employed approach towards enhanced photocatalytic performance, with one of the key rationales for doing this being to separate photoexcited charges, ...affording them longer lifetimes in which to react with adsorbed species. Here we examine three composite photocatalysts using either WO3, TiO2 or CeO2 with BiVO4 for the degradation of model dyes Methylene Blue and Rhodamine B. Each of these materials (WO3, TiO2 or CeO2) has a different band edge energy offset with respect to BiVO4, allowing for a systematic comparison of these different arrangements. It is seen that while these offsets can afford beneficial charge transfer (CT) processes, they can also result in the deactivation of certain reactions. We also observed the importance of localized dye concentrations, resulting from a strong affinity between it and the surface, in attaining high overall photocatalytic performance, a factor not often acknowledged. It is hoped in the future that these observations will assist in the judicious selection of semiconductors for use as composite photocatalysts.
Photo-crosslinkable hydrogels, in particular gelatin methacryloyl (GelMa), are gaining increasing importance in biofabrication and tissue engineering. While GelMa is often described as mechanically ...'tunable', clear relationships linking the photocrosslinking conditions to reaction rates, and the resulting mechanical properties, have not been described. Meanwhile the conditions employed in the literature are disparate, and difficult to compare. In this work, in situ rheological measurements were used to quantify the relative rate of reaction of GelMa hydrogels with respect to light intensity, exposure time and photo-initiator concentration. In addition the UV degradation of the photo-initiator Irgacure 2959 was measured by UV-vis spectroscopy, and used to estimate the rate of free radical production as a function of light exposure. Using these data an expression was derived which predicts the mechanical properties of GelMa hydrogels produced across a wide range of crosslinking conditions. The model was validated through fabrication of a GelMa gradient which matched predicted properties. Human mesenchymal stem cells encapsulated in crosslinked GelMa exhibited high (>90%) viability post encapsulation, however metabolic activity over one week was influenced by the intensity of light used during crosslinking. The expressions described may be used to aid rational choices of GelMa photocrosslinking conditions, especially in cell encapsulation experiments where minimising the cytotoxic elements in the reaction is a priority.
Highlights ► We evaluated astrocyte activation and inflammation involvement in human epilepsy samples. ► High GFAP is associated with increased AQP4, CX43, m-calpain, and L-type Ca2+ channels. ► ...Kir4.1, dystrophin, and α-syntrophin are decreased in human epilepsy. ► Inflammatory markers and glutamate receptors/subunits are also increased. ► Astrocyte-related inflammation may be a significant target for new epilepsy therapy.
A ternary composite of CNT/polypyrrole/hydrous MnO2 is prepared by in situ chemical method and its electrochemical performance is evaluated by using cyclic voltammetry (CV), impedance measurement and ...constant-current charge/discharge cycling techniques. For comparative purpose, binary composites such as CNT/hydrous MnO2 and polypyrrole/hydrous MnO2 are prepared and also investigated for their physical and electrochemical performances. The specific capacitance (SC) values of the ternary composite, CNT/hydrous MnO2 and polypyrrole/hydrous MnO2 binary composites estimated by CV technique in 1.0M Na2SO4 electrolyte are 281, 150 and 35Fg-1 at 20mVs-1 and 209, 75 and 7Fg-1 at 200mVs-1, respectively. The electrochemical stability of ternary composite electrode is investigated by switching the electrode back and forth for 10,000 times between 0.1 and 0.9V versus Ag/AgCl at 100mVs-1. The electrode exhibits good cycling stability, retaining up to 88% of its initial charge at 10,000th cycle. A full cell assembled with the ternary composite electrodes shows a SC value of 149Fg-1 at a current loading of 1.0mAcm-2 during initial cycling, which decreased drastically to a value of 35Fg-1 at 2000th cycle. Analytical techniques such as scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), Brunauer-Emmet-Teller (BET) surface area measurement and inductively coupled plasma-atomic emission spectrometry (ICP-AES) are also used to characterize the composite materials.
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