Microfluidic Production of Biodegradable Microcapsules for Sustained Release of Hydrophilic Actives

Biodegradable microcapsules with a large aqueous lumen and ultrathin membrane are microfluidically designed for sustained release of hydrophilic bioactives using water‐in‐oil‐in‐water double‐emulsion drops as a template. As a shell phase, an organic solution of poly(lactic‐co‐glycolic acid) is used, which is consolidated to form a biodegradable membrane. The encapsulants stored in the lumen are released over a long period of time as the membranes degrade. The period can be controlled in a range of —three to five months at neutral pH condition by adjusting membrane thickness, providing highly sustained release and potentially enabling the programed release of multiple drugs. At acidic or basic condition, the degradation is accelerated, leading to the release in the period of approximately two months. As the membrane is semipermeable, the microcapsules respond to the osmotic pressure difference across the membrane. The microcapsules are inflated in hypotonic condition and deflated in hypertonic condition. Both conditions cause cracks on the membrane, resulting in the fast release of encapsulants in a day. The microcapsules implanted in mice also show sustained release, despite the period is decreased to a month. It is believed that the microcapsules are promising for the in vivo sustained release of drugs for high and long‐term efficacy.     

Continuous Coaxial Electrohydrodynamic Atomization System for Water‐Stable Wrapping of Magnetic Nanoparticles

An electrohydrodynamic atomization (EHDA) system that generates an electrospray can achieve particle formation and encapsulation by accumulating an electric charge on liquid flowing out from the nozzle. A novel coaxial EHDA system for continuous fabrication of water‐stable magnetic nanoparticles (MNPs) is established, based on a cone‐jet mode of electrospraying. Systemic variables, such as flow rates from dual nozzles and inducing voltages, are controlled to enable the preparation of water‐soluble MNPs coated by polysorbate 80. The PEGylated MNPs exhibit water stability. The magnetic resonance imaging potential of these MNPs is confirmed by in vivo imaging using a gastric cancer xenograft mouse model. Thus, this advanced coaxial EHDA system demonstrates remarkable capabilities for the continuous encapsulation of MNPs to render them water‐stable while preserving their properties as imaging agents.     

Nitrogen solubility in liquid manganese and ferromanganese alloys

The nitrogen solubilities in liquid manganese, manganese-iron, manganese-carbon, and manganese-iron-carbon alloys have been measured by the gas-liquid metal equilibration technique in the temperature range of 1623 to 1823 K. The equilibrium nitrogen content in pure liquid manganese at an atmospheric nitrogen pressure is high, and it does not follow Sievert’s law, i.e., f _N is not unity. The reduced nitrogen partial pressures by dilution with argon enabled us to obtain more reliable information on the thermodynamics of nitrogen in liquid manganese. The nitrogen dissolution follows Sievert’s law at nitrogen contents below 1 wt pct. The standard free-energy change for the dissolution of nitrogen in pure liquid manganese has been determined as −67,222+30.32T J/g atom, with the standard state of nitrogen taken as a 1 wt pct solution. Carbon and iron in manganese-rich melts decrease the nitrogen solubility significantly. The first- and second-order interaction parameters between nitrogen and other elements in manganese alloy melts have been determined. The activity coefficient of nitrogen in a ferromanganese alloy melt can be expressed as

Surface treatment effect of carbon fiber fabric counter electrode in dye sensitized solar cell

Dye sensitized solar cells (DSSC) with surface modified carbon fiber fabric (CF) counter electrodes were prepared and tested. Four different type of CF were used; carbon fiber (CF); carbon fiber etched with NaOH (ECF); carbon fiber with thermally deposited platinum (CFPt); and carbon fiber etched with NaOH followed by thermal deposition of platinum (ECFPt). For comparison, DSSC with thermally Pt deposited fluorine doped tin oxide (FTO/Pt) glass counter electrode was also prepared and tested. Scanning electron microscope (SEM) proved that surface morphology of the carbon fiber was roughened by the etching process and platinum deposition process. The I-V curves of each DSSC were measured under simulated light (1 Sun, AM 1.5) to get open circuit voltage (Voc), short circuit current density (Jsc), fill factor (FF) and efficiency (eta). Electrochemical impedance spectroscopy of each cell was measured also. It was found that higher efficiency is obtained in order of using ECFPt > CFPt > FTO/Pt > ECF > CF counter electrode.     

Modern electric insulating materials for the insulation systems of rotating electric machines

Modern insulation systems of turbo- and hydrogenerators, large electric machines, and traction motors based on new electric insulating materials (EIMs) produced by the JSC Elinar Holding Company (Elinar HC) are described briefly. The technical characteristics of some new EIMs are given.     

Online Signal Injection Through a Bus-Referenced Current Transformer

An online signal injection approach based on a special current transformer is proposed as part of a solution for improving the test setup of transfer function diagnostics of transformers. However, the method is general and applicable to many types of substation equipment, such as circuit breakers and transmission lines. The system allows a high-power, high-frequency test signal to be injected directly on a high-voltage bus of an energized system. Due to the self-contained nature of the injector, no external power supplies or signal generators are needed and the design does not need to be ground-referenced. The system can thus be at the bus potential. In conjunction with wireless communication for control, no isolator bushings are required and the device can be constructed as a sleeve to be mounted around the busbar. This allows for economical retrofitting to existing installations. In this paper, the operational need for such an injection device is discussed, followed by the theory behind the proposed concept. Finally, a low-voltage, optically controlled, self-powered prototype is designed and demonstrated online to show the practical validity of the concept.