Electrical stimulation of cells allows exogenous electric signals as stimuli to manipulate cell growth, preferential orientation and bone remodelling. In this study, commercially pure titanium discs ...were utilised in combination with a custom-built bioreactor to investigate the cellular responses of human mesenchymal stem cells via in-vitro functional assays. Finite element analysis revealed the homogeneous delivery of electric field in the bioreactor chamber with no detection of current density fluctuation in the proposed model. The custom-built bioreactor with capacitive stimulation delivery system features long-term stimulation with homogeneous electric field, biocompatible, sterilisable, scalable design and cost-effective in the manufacturing process. Using a continuous stimulation regime of 100 and 200 mV/mm on cp Ti discs, viability tests revealed up to an approximately 5-fold increase of cell proliferation rate as compared to non-stimulated controls. The human mesenchymal stem cells showed more elongated and differentiated morphology under this regime, with evidence of nuclear elongation and cytoskeletal orientation perpendicular to the direction of electric field. The continuous stimulation did not cause pH fluctuations and hydrogen peroxide production caused by Faradic reactions, signifying the suitability for long-term toxic free stimulation as opposed to the commonly used direct stimulation regime. An approximate of 4-fold increase in alkaline phosphatase production and approximately 9-fold increase of calcium deposition were observed on 200 mV/mm exposed samples relative to non-stimulated controls. It is worth noting that early stem cell differentiation and matrix production were observed under the said electric field even without the presence of chemical inductive growth factors.
This manuscript presents a study on combining pure titanium (primarily preferred as medical implant materials) and electrical stimulation in a purpose-built bioreactor with capacitive stimulation delivery system. A continuous capacitive stimulation regime on titanium disc has resulted in enhanced stem cell orientation, nuclei elongation, proliferation and differentiation as compared to non-stimulated controls. We believe that this manuscript creates a paradigm for future studies on the evolution of healthcare treatments in the area of targeted therapy on implantable and wearable medical devices through tailored innovative electrical stimulation approach, thereby influencing therapeutic conductive and electroactive biomaterials research prospects and development.
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Electrotrawling is currently the most promising alternative for conventional beam trawls targeting sole and shrimp, meeting both the fisherman’s aspirations and the need for more environmentally ...friendly fishing techniques. Before electrotrawling can be further developed and implemented on a wider scale, more information is needed about the effects of electrical pulses on marine organisms. Adult Dover sole (Solea solea L.) and Atlantic cod (Gadus morhua L.) were used in the present study as model species for flatfish and roundfish, respectively. These animals were exposed to homogeneously distributed electrical fields with varying values of the following parameters: frequency (5–200Hz), electrical field strength (100–200V/m), pulse polarity, pulse shape, pulse duration (0.25–1ms) and exposure time (1–5s). The goal was to determine the range of pulse parameters which can be regarded as safe and thereby also to evaluate the effect of the pulses already being used in commercial electrotrawls. Fish behaviour during and shortly after exposure, 14-days post exposure mortality rates, as well as gross and histological examination were used to evaluate possible effects. During exposure, both species showed an escape response below a frequency of 20Hz and a cramp reaction above 40Hz. These reactions were immediately followed by post-exposure escape behaviour and at high electrical loads cod showed tonic-clonic epileptiform seizures. No mortality was observed and histological examination did not reveal any abnormalities, except for one cod showing a spinal injury. These data reveal the absence of irreversible lesions in sole as a direct consequence of exposure to electric pulses administered in the laboratory, while in cod, more research is needed to assess cod’s vulnerability for spinal injuries when exposed to the cramp pulses.
Klebsiella pneumoniae strains may act as opportunistic pathogens infecting susceptible patients, or as hypervirulent germs infecting healthy people, or as multidrug-resistant organisms due to ...extended-spectrum beta-lactamase (ESBL)-production provoking infection outbreaks in hospital settings and communities. Consequently, it is a priority to encourage the development of simple, rapid and economical methods for the molecular subtyping of the outbreak strains and then to facilitate the infection control. Pulsed field gel electrophoresis (PFGE) remains a good choice for K. pneumoniae subtyping and for the laboratory confirmation of outbreaks. We report the implementation of a rapid protocol for characterizing K. pneumoniae isolates by contour clamped homogeneous electric field (CHEF) in mini gels in a total analysis time of less than 12 h. This approach is based on the preparation of K. pneumoniae DNA of PFGE-quality by a single incubation step of immobilized bacteria for 2 h with a nonenzymatic solution containing 4 M urea and nonionic detergents with further XbaI DNA fingerprint resolution in CHEF mini gels in 5.5 h. The DNA suitable for PFGE obtained by this procedure was approximately 91% of the total DNA in the plugs. This procedure enabled the reproducible subtyping of 26 isolates of K. pneumoniae and three of K. oxytoca. The XbaI DNA fingerprint analysis in CHEF mini gels was able to discriminate the seven isolates of K. pneumoniae that were epidemiologically related and the nineteen that were unrelated. The nonenzymatic DNA plugs preparation reported in this paper is a cost-effective alternative for K. pneumoniae PFGE subtyping in laboratories where the technique is already implemented.
Abstract
The molecular karyotype of Hypsizygus marmoreus was explored by contour-clamped homogeneous electric field gel electrophoresis. Eleven chromosomal bands were separated from the dikaryotic ...mycelia of H. marmoreus (strain Hm 3-10), and the chromosomes ranged in size from 1.9 to 5.8 Mb. The total genome size of the strain was estimated to be 36.3 Mb. The chromosome numbers were also confirmed by telomere fingerprinting, and 22 telomeric bands were identified. This result suggests that 11 chromosomes exist in Hm 3-10. The marker sequences for each chromosome were determined and were applied to identify each chromosome. Karyotyping and Southern blot analysis revealed that the size of chromosomes in the basidiospores were greatly different from those of parental dikaryon Hm 3-10 cells.
Electrophoretic karyotyping of Hypsizygus marmoreus and evaluation of variation among its basidiospores has been carried out, using CHEF gel electrophoresis.
Graphical Abstract Figure.
Electrophoretic karyotyping of Hypsizygus marmoreus and evaluation of variation among its basidiospores has been carried out, using CHEF gel electrophoresis.
As a new environmental-friendly gas insulating medium, perfluoroisobutyronitrile (C 4 F 7 N) has been widely concerned in recent years due to its relatively low global warming potential and excellent ...dielectric strength, which has the potential to replace the most greenhouse gas, sulfur hexafluoride(SF 6 ). However, there are a few systematic studies on the influence of gas pressure and mixing ratio on the dielectric strength of C 4 F 7 N/CO 2 gas mixture at present. In this paper, the power frequency breakdown characteristics of C 4 F 7 N/CO 2 gas mixture under different pressure and mixing ratio conditions were tested using the gas insulation performance test platform. The optimal mixing ratio and pressure range of C 4 F 7 N/CO 2 gas mixture for engineering application were also discussed. It is found that the breakdown voltages of C 4 F 7 N/CO 2 gas mixture show a saturated growth trend with gas pressure and mixing ratio. The breakdown voltage of the gas mixture with 10% C 4 F 7 N can reach 80% of pure SF 6 under the same condition. The insulation performance of the gas mixture with 20% C 4 F 7 N can reach more than 95% of pure SF 6 . Relevant results indicate that the gas mixture with 4%-12% C 4 F 7 N has the potential to be applied to high-voltage gas-insulated equipment.
•Method for next-generation sequencing of fungal single chromosome was established.•Small chromosome harbors pathogenicity related genes in some F. oxysporum isolates.•Sequencing of single chromosome ...reveals rearrangement/duplication of chromosomes.
A small chromosome in reference isolate 4287 of F. oxysporum f. sp. lycopersici (Fol) has been designated as a ‘pathogenicity chromosome’ because it carries several pathogenicity related genes such as the Secreted In Xylem (SIX) genes. Sequence assembly of small chromosomes in other isolates, based on a reference genome template, is difficult because of karyotype variation among isolates and a high number of sequences associated with transposable elements. These factors often result in misassembly of sequences, making it unclear whether other isolates possess the same pathogenicity chromosome harboring SIX genes as in the reference isolate. To overcome this difficulty, single chromosome sequencing after Contour-clamped Homogeneous Electric Field (CHEF) separation of chromosomes was performed, followed by de novo assembly of sequences. The assembled sequences of individual chromosomes were consistent with results of probing gels of CHEF separated chromosomes with SIX genes. Individual chromosome sequencing revealed that several SIX genes are located on a single small chromosome in two pathogenic forms of F. oxysporum, beyond the reference isolate 4287, and in the cabbage yellows fungus F. oxysporum f. sp. conglutinans. The particular combination of SIX genes on each small chromosome varied. Moreover, not all SIX genes were found on small chromosomes; depending on the isolate, some were on big chromosomes. This suggests that recombination of chromosomes and/or translocation of SIX genes may occur frequently. Our method improves sequence comparison of small chromosomes among isolates.
For decades now, DNA fingerprinting by means of pulsed-field gel electrophoresis (PFGE) continues to be the most widely used to separate large DNA molecules and distinguish between different strains ...in alternating pulses. This is done by isolating intact chromosomal DNA and using restriction enzymes with specific restriction sites to generate less than 30 restriction fragments from 50 Kb to 10 Mbp. These results make clone-specific band profiles easy to compare. Specialized equipment is required for the optimization of DNA separation and resolution, among which a contour-clamped homogeneous electric field (CHEF) apparatus is the most commonly used. As a result, the PFGE analysis of a bacterial genome provides useful information in terms of epidemiological investigations of different bacterial pathogens. For
subtyping, despite its limitations and the emergence of alternative methods, PFGE analysis has proven to be an adequate choice and the gold standard for determining genetic relatedness, especially in outbreak detection and short-term surveillance in the veterinary field.
An n-type polycrystalline silicon thin-film transistor (poly-Si TFT) with a bottom-gate structure using excimer laser annealing (ELA) for active matrix organic light-emitting diode displays is ...proposed. A problem with bottom-gate poly-Si TFTs (BGPs) using ELA, namely, the disconnection of poly-Si at the boundary of the gate metal during the ELA crystallisation, was solved by developing a novel process to control the slope of the gate metal. We realised ELA BGPs with pure-Mo gate having a thickness of more than 150 nm. The BGPs have better breakdown voltage characteristics compared with the conventional top-gate poly-Si TFTs because of its flat channel region and homogeneous electric field distribution in the gate insulator.
The paper describes anomaly origination on current or voltage characteristics in time of positive potential on small curvature radius electrode rod against plane electrodes. An anomaly phenomenon ...occurred in the narrow voltage area in a high non-homogenous electric field close to the electrode (E > 107 V m−1). A mathematical – physical analysis of the observed processes in close proximity to the electrode with the above mentioned form is made. The differential equations, which analytically and theoretically describe this phenomenon, are compiled and solved. The space charge created by element particles (electrons, ions) which causes negative differential conductivity origination in narrow voltage area by their behaviour in electric field, plays a substantial role in this phenomenon. Current–voltage characteristics at both polarities of corona electrode were continuously measured at the study of static and dynamic processes occurring during discharge in the surrounding of a small curvature radius electrode. It was proved that an anomaly, in the form of negative differential conductivity (dI/dU < 0), appeared on a highly curved electrode at positive polarity in a narrow voltage area. This phenomenon was subjected to detailed experimental research including investigation of the influence of the shape and material of the electrode (output voltage), electrode temperature, influence of photoionization on the profile of the anomaly, the contribution of exoelectrons to particle distribution, and study of electrochemical potential of metal electrode. Oscillation of low ionized plasma at positive and negative polarity of small curvature radius electrodes has been analyzed. At the same time, the influence of the external forced electric field on the change of current–voltage characteristic profile was investigated. Theoretical justification of the anomaly phenomenon resulted from a change of energy conditions in the investigated place (the distance limit from the electrode is 10−4–10−6 m).
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