Reconstituted Keratin Biomaterial with Enhanced Ductility

Nowadays the waste from protein fibres represents an important renewable source for a new generation of biomaterials and promising competitors for carbohydrate based biomaterials. Regenerated keratin biomaterials are biodegradable in vivo and in vitro, biocompatible, and support cell attachment and proliferation; however, their major drawback has been their weak mechanical properties such as ductility. The following study was conducted in an attempt to improve the ductility of reconstituted keratin films obtained from Australian merino wool fibres. Keratin was extracted from wool fibres according to an established protocol proposed by Yamauchi, and then dialyzed and desalted by multiple diafiltration wash cycles. The resulting keratin film was transparent, biodegradable, and, opposite to its predecessors, mechanically durable, possessing a Young modulus about 12.5 MPa with 35% extensibility. The polypeptide chains were found to rearrange themselves in the β-sheet state in this keratin film, which was shown to be semi-crystalline. This film, unlike its predecessors, did not support human cell proliferation. These properties of the diafiltered keratin film have led us to think that diafiltration resulted in producing a totally new keratin film, which is envisaged to find applications in various areas

Hierarchical control in microgrid

It is required to utilize several control loops together to increase reliability and performance of microgrids. The current and voltage magnitudes, frequency and angle information, active and reactive power data provide the involved feedback for normal and island mode operations of microgrid. The hierarchical control structure of microgrid is responsible for microgrid synchronization, optimizing the management costs, control of power share with neighbor grids and utility grid in normal mode while it is responsible for load sharing, distributed generation, and voltage/frequency regulation in both normal and islanding operation modes. The load control of microgrid is performed by using more sophisticated electronic devices as well as regular circuit breakers. This regulation capacity could be improved since the ESS decreases the dependency to primary power sources. Although several improvements have been experienced in microgrid control strategies, the most intensive research areas are listed as decreasing the structural instability, improving the system performance to increase reliability, monitoring the harmonic contents, scaling the control infrastructure, enhancing the operation characteristics in error states, and implementing new control algorithms for normal and islanding operation. The microgrid system has hierarchical control infrastructure in different levels similar to conventional grids. The microgrid requires enhanced control techniques to manage any level of system. Safe operation of microgrid in both operation modes and connection and disconnection between microgrid and utility grid are depended to microgrid control techniques. The controllers should ensure to operate the system regarding to predefined circumstances and efficiency requirements. The hierarchical control methods and applications of microgrid infrastructure are presented in the proposed chapter

Fractionation of graphene oxide single nano-sheets in water-glycerol solutions using gradient centrifugation

A centrifugation method for the separation and fractionation of graphene oxide (GO) single nano-sheets in the size range of 150-850 nm is reported. The measured electrophoretic mobility of the fractionated single sheets ranges from -0.2 to -1.4 μm cm/V·s where the interpreted zeta potentials vary from -3 mV to -17 mV with increasing sheet size. The single GO sheets show auto-fluorescence in the visible range of 350-650 nm using an excitation wavelength of 200 nm. Furthermore, the GO nano-sheets functionalized using PEG are found to be non-cytotoxic in in-vitro at concentrations up to 90 μg/ml, with a small reduction in cell viability -10%- at 260 μg/ml. The observed concentration-dependence of the cytotoxicity potentially explains the differing conclusions on cytotoxic potential reported in the literature. The GO nano-sheets therefore have the potential to be used as fluorescent drug delivery carriers of specific size

Fractionation of graphene oxide single nano-sheets in water-glycerol solutions using gradient centrifugation

A centrifugation method for the separation and fractionation of graphene oxide (GO) single nano-sheets in the size range of 150-850 nm is reported. The measured electrophoretic mobility of the fractionated single sheets ranges from -0.2 to -1.4 μm.cm/V·s where the interpreted zeta potentials vary from -3 mV to -17 mV with increasing sheet size. The single GO sheets show auto-fluorescence in the visible range of 350-650 nm using an excitation wavelength of 200 nm. Furthermore, the GO nano-sheets functionalized using PEG are found to be non-cytotoxic in in-vitro at concentrations up to 90 μg/ml, with a small reduction in cell viability -10%- at 260μg/ml. The observed concentration-dependence of the cytotoxicity potentially explains the differing conclusions on cytotoxic potential reported in the literature. The GO nano-sheets therefore have the potential to be used as fluorescent drug delivery carriers of specific size

Targeted graphene oxide networks : cytotoxicity and synergy with anticancer agents

An effective strategy to inhibit endocytosis in cancer cells is presented where modified net-type graphene oxide (GO) sheets, bound with multiple cell surface receptors, are introduced and synthesized as novel anticancer agents. The results suggest that the binding connects GO sheets with neighboring lipid rafts, neutralizes endocytosis, and causes metabolic deprivation. As a result, tumor cell survival and proliferation are reduced. Live cell confocal microscopy imaging reveals that GO-PEGFA (folate-PEGylated GO) (PEG, polyethylene glycol) is internalized by tumor cells, while GO-PEGRGD (tripeptide Arg-Gly-Asp PEGylated GO) associates with the external cell membrane (not internalized). In vitro exposure of tumor cells to GO-PEGFA or GO-PEGRGD reduces the cell viability by 35%, compared to 50% reduction using methotrexate (100 μM). The combination of modified GO sheets with methotrexate or doxorubicin shows a greater toxicity (80% reduction in cell viability) than the individual agents. The proposed setup demonstrates a significant synergy in limiting tumor cell growth

Modern Control Methods for Adaptive Droop Coefficients’ Design

The microgrid controller comprises of cascaded “droop–voltage–current” control modules. The voltage and current controllers are basically proportional plus integral (PI)-type control logics. So, the efficacy of these controllers depends on the accuracy of the PI gain parameter tuning. Besides, the droop control logic supplies the reference voltage required for voltage control and the voltage control logic supplies the reference current required for the current control. Therefore, the total control operation depends on the effective design of droop control logic, which depends on the design of droop coefficients and their adaptivity to respond with respect to a disturbance. There are many conventional methods available as mentioned in the literature; however, to meet the modern power system requirements, these conventional methods have to be updated with features such as adaptivity, disturbance rejection, capability to address inertia related issues. With this intent, this chapter provides modern control methods for adaptive droop coefficients’ design. In brief, this chapter presents a novel droop controller design method that involves fuzzy logic-based adaptive p − ω droop coefficient design and model reference-based adaptive q − v droop coefficient design. This method facilitates the controller to adaptively respond according to the disturbances and thereby provides effective closed-loop control actions to improve the transient response of the system. The comparisons with the conventional methods are presented with the help of simulation and experimental results to persuade the importance of the proposed adaptive droop control method