Ultrafast Metal-Free Microsupercapacitor Arrays Directly Store Instantaneous High-Voltage Electricity from Mechanical Energy Harvesters.

Harvesting renewable mechanical energy is envisioned as a promising and sustainable way for power generation. Many recent mechanical energy harvesters are able to produce instantaneous (pulsed) electricity with a high peak voltage of over 100 V. However, directly storing such irregular high-voltage pulse electricity remains a great challenge. The use of extra power management components can boost storage efficiency but increase system complexity. Here utilizing the conducting polymer PEDOT:PSS, high-rate metal-free micro-supercapacitor (MSC) arrays are successfully fabricated for direct high-efficiency storage of high-voltage pulse electricity. Within an area of 2.4 × 3.4 cm2 on various paper substrates, large-scale MSC arrays (comprising up to 100 cells) can be printed to deliver a working voltage window of 160 V at an ultrahigh scan rate up to 30 V s-1. The ultrahigh rate capability enables the MSC arrays to quickly capture and efficiently store the high-voltage (≈150 V) pulse electricity produced by a droplet-based electricity generator at a high efficiency of 62%, significantly higher than that (<2%) of the batteries or capacitors demonstrated in the literature. Moreover, the compact and metal-free features make these MSC arrays excellent candidates for sustainable high-performance energy storage in self-charging power systems.

Order of magnitude improvement of nano-contact spin torque nano-oscillator performance.

Spin torque nano-oscillators (STNO) represent a unique class of nano-scale microwave signal generators and offer a combination of intriguing properties, such as nano sized footprint, ultrafast modulation rates, and highly tunable microwave frequencies from 100 MHz to close to 100 GHz. However, their low output power and relatively high threshold current still limit their applicability and must be improved. In this study, we investigate the influence of the bottom Cu electrode thickness (tCu) in nano-contact STNOs based on Co/Cu/NiFe GMR stacks and with nano-contact diameters ranging from 60 to 500 nm. Increasing tCu from 10 to 70 nm results in a 40% reduction of the threshold current, an order of magnitude higher microwave output power, and close to two orders of magnitude better power conversion efficiency. Numerical simulations of the current distribution suggest that these dramatic improvements originate from a strongly reduced lateral current spread in the magneto-dynamically active region.

The double electrostatic ion ring experiment: a unique cryogenic electrostatic storage ring for merged ion-beams studies.

We describe the design of a novel type of storage device currently under construction at Stockholm University, Sweden, using purely electrostatic focussing and deflection elements, in which ion beams of opposite charges are confined under extreme high vacuum cryogenic conditions in separate "rings" and merged over a common straight section. The construction of this double electrostatic ion ring experiment uniquely allows for studies of interactions between cations and anions at low and well-defined internal temperatures and centre-of-mass collision energies down to about 10 K and 10 meV, respectively. Position sensitive multi-hit detector systems have been extensively tested and proven to work in cryogenic environments and these will be used to measure correlations between reaction products in, for example, electron-transfer processes. The technical advantages of using purely electrostatic ion storage devices over magnetic ones are many, but the most relevant are: electrostatic elements which are more compact and easier to construct; remanent fields, hysteresis, and eddy-currents, which are of concern in magnetic devices, are no longer relevant; and electrical fields required to control the orbit of the ions are not only much easier to create and control than the corresponding magnetic fields, they also set no upper mass limit on the ions that can be stored. These technical differences are a boon to new areas of fundamental experimental research, not only in atomic and molecular physics but also in the boundaries of these fields with chemistry and biology. For examples, studies of interactions with internally cold molecular ions will be particular useful for applications in astrophysics, while studies of solvated ionic clusters will be of relevance to aeronomy and biology.

A method suitable for the isolation of monoclonal antibodies from large volumes of serum-containing hybridoma cell culture supernatants.

A method suitable for the isolation of monoclonal antibodies from large volumes of serum-containing hybridoma cell culture supernatants is described. The purification is carried out in three steps; buffer exchange by chromatography on Sephadex G-25, fractionation by cation exchange chromatography on S Sepharose Fast Flow and, as a final step, gel filtration on Sephacryl S-200 HR. Experience from purification of 11 different mouse monoclonal antibodies is reported.

Process-scale purification from cell culture supernatants: monoclonal antibodies.

A method for processing monoclonal antibodies (mAb) from large volumes of cell culture supernatants using recently developed high performance and fast flow chromatography media is described. A high-antibody producing mouse hybridoma cell line was adapted to low serum containing medium (1% foetal calf serum) for the production of anti-tissue Plasminogen Activator (anti-tPA) monoclonal antibody (murine subclass IgG1). The process consisted of three main chromatographic steps: desalting, cation exchange on S Sepharose Fast Flow and gel filtration on Superose 6 prep grade. With this process for the purification of anti-tPA monoclonal antibody, the final product was greater than 95% pure with a total recovery of 75% i.e. 1.4 g was recovered in 0.345 l from 35 l of culture supernatant originally containing 1.9 g of mAb. The adaptation of this process for purification of other monoclonal antibodies is discussed.

Chemical modification of Cys-374 of actin interferes with the formation of the profilactin complex.

Chemical modification of the cysteine residue 374 of actin, both with N-ethylmaleimide and with the fluorescent probe N-(1-pyrenyl)iodoacetamide, is shown to counteract the inhibiting effect of profilin on actin polymerization.

The profilin--actin complex: further characterization of profilin and studies on the stability of the complex.

Two forms of profilin can be isolated from calf spleen profilactin by chromatography on phosphocellulose. They can be distinguished by C-terminal analysis, which suggests that one of them lacks the C-terminal tyrosine and the penultimate glutamine residue. This is confirmed by treatment of profilin (+Tyr) with carboxypeptidase A, which removes the C-terminal tyrosine (rapidly) and the penultimate glutamine residue (slowly), and thereby converts it to the other form as judged by chromatography on phosphocellulose. The two forms of profilin differ also in solubility and in mobility during so-called 'charge shift' electrophoresis, indicating differences in their ability to bind detergents. Recombination studies using profilin with or without a modified C-terminus demonstrated that this part of profilin is relatively unimportant for the interaction with actin. On the other hand, experiments with native and modified actin revealed that the C-terminus of actin is of the utmost importance for the stability of the profilactin complex. Analysis of the u.v. absorbance and far-u.v. circular dichroism spectra of profilin and actin did not reveal any major changes in the conformation of the proteins accompanying the modifications at the C-terminal ends. Finally, it is reported that purified profilactin contains variable amounts of a protein factor which causes an apparent stabilization of profilactin in solution.