A High Efficiency and Low Ripple Cross-Coupled Charge Pump Circuit

A fully integrated cross-coupled charge pump circuit with four-clock signals and a new method of body bias have been proposed. The new clock scheme eliminates all of the reversion power loss and reduces the ripple voltage. In addition, the largest voltage differences between the terminals of all transistors do not exceed the supply voltage. We have also solved the gate-oxide overstress problem in the conventional charge pump circuits and enhanced the reliability. The proposed charge pump circuit has been simulated using Spectre and in the TSMC 0.18um CMOS process. The simulation results show that the maximum voltage conversion efficiency of the new 3-stage cross-coupled circuit with an input voltage of 1.5V is 99.8%. Moreover, the output ripple voltage has been significantly reduced.Peer reviewe

High Efficiency Cross-Coupled Charge Pump Circuit with Four-Clock Signals

© Allerton Press, Inc. 2018A fully integrated cross-coupled charge pump circuit for boosting dc-to-dc converter applications with four-clock signals has been proposed. With the new clock scheme, this charge pump eliminates all of the reversion power loss and reduces the ripple voltage. In addition, the largest voltage differences between the terminals of all transistors do not exceed the power supply voltage for solving the gate-oxide overstress problem in the conventional charge pump circuits and enhancing the reliability. This proposed charge pump circuit does not require any extra level shifter; therefore, the power efficiency is increased. The proposed charge pump circuit has been simulated using Spectre in the TSMC 0.18 μm CMOS process. The simulation results show that the maximum voltage conversion efficiency of the new 3-stage cross-coupled circuit with an input voltage of 1.5Vis 99.8%. According to the comparison results of the conventional pump and the enhanced charge pump proposed, the output ripple voltage has been significantly reduced.Peer reviewe

A robust high-efficiency cross-coupled charge pump circuit without blocking transistors

This document is the Accepted Manuscript version of the following article: Minglin Ma, Xinglong Cai, Yichuang Sun, and Nike George, ‘A robust high-efficiency cross-coupled charge pump circuit without blocking transistors’, Analog Integrated Circuits and Signal Processing, Vol. 95 (3): 395-401, June 2018. Under embargo until 16 March 2019. The final publication is available at Springer via: https://doi.org/10.1007/s10470-018-1149-xA fully integrated cross-coupled charge pump circuit with a new clock scheme has been presented in this paper. The new clock scheme ensures that all NMOS pre-charge transistors are turned off when the voltages of main clock signals are high. Notably, all PMOS transfer transistors will be turned off when the voltages of the main clock signals are low. As a result, the charge pump eliminates all of the reversion power loss and reduces the ripple voltage. The proposed charge pump has a better performance even in scenarios where the main clock signals are mismatched. The proposed charge pump circuit was simulated using spectre in the TSMC 0.18 µm CMOS process. The simulation results show that the proposed charge pump circuit has a high voltage conversion efficiency and low ripple voltage.Peer reviewe

Exploring challenges and supports for writing in Standard Australian English for Australian secondary English as an Additional Language/Dialect Students: A scoping study

The overall purpose of this study was to explore the identified language challenges and supports for writing in Standard Australian English for secondary English as an Additional Language or Dialect (EAL/D) students. An initial review of the academic literature revealed that this research topic has not been extensively researched within the Australian context. For this reason, this research project involved a systematic scoping study of the academic literature, based on the framework of Arksey and O’Malley (2005). This scoping study mapped the current research, and through a content analysis, synthesised the findings. In total, Level 1 searching of five digital data bases revealed 77 potential studies based on key word searches of titles and abstracts, published from 2010-2022. Further reading and searching refined these to 35 articles that addressed the research question. These articles revealed a range of themes that either challenged or supported the writing process for Australian EAL/D secondary students. These related to aspects at the policy, contextual and classroom level that shaped teachers’ knowledge practice, beliefs and skills in relation to teaching and learning, planning and assessing writing in a range of secondary areas. Gaps in the literature and a way forward, as well as implications for the future are discussed

Copper toxicity links to pathogenesis of Alzheimer’s disease and therapeutics approaches

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. Alzheimer’s disease (AD) is an irreversible, age-related progressive neurological disorder, and the most common type of dementia in aged people. Neuropathological lesions of AD are neurofibrillary tangles (NFTs), and senile plaques comprise the accumulated amyloid-beta (Aβ), loaded with metal ions including Cu, Fe, or Zn. Some reports have identified metal dyshomeostasis as a neurotoxic factor of AD, among which Cu ions seem to be a central cationic metal in the formation of plaque and soluble oligomers, and have an essential role in the AD pathology. Cu-Aβ complex catalyzes the generation of reactive oxygen species (ROS) and results in oxidative damage. Several studies have indicated that oxidative stress plays a crucial role in the pathogenesis of AD. The connection of copper levels in AD is still ambiguous, as some researches indicate a Cu deficiency, while others show its higher content in AD, and therefore there is a need to increase and decrease its levels in animal models, respectively, to study which one is the cause. For more than twenty years, many in vitro studies have been devoted to identifying metals’ roles in Aβ accumulation, oxidative damage, and neurotoxicity. Towards the end, a short review of the modern therapeutic approach in chelation therapy, with the main focus on Cu ions, is discussed. Despite the lack of strong proofs of clinical advantage so far, the conjecture that using a therapeutic metal chelator is an effective strategy for AD remains popular. However, some recent reports of genetic-regulating copper transporters in AD models have shed light on treating this refractory disease. This review aims to succinctly present a better understanding of Cu ions’ current status in several AD features, and some conflicting reports are present herein

Nanostructured electrospun fibers : from superhydrophobicity to block copolymer self-assembly

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2008.Includes bibliographical references (p. 166-176).Electrospinning has emerged in recent years as a relatively easy, efficient and robust method to make ultrafine continuous fibers with diameter on the order of -100 nm from a variety of materials. As a result, numerous applications for electrospun fibers have already been demonstrated including the commercialized ones in the areas of filtration and tissue engineering. However, in most cases, the nanofibers are homogeneous; the development of external and internal nanostructures could significantly expand the applications of these fibers. The goal of this dissertation is therefore to develop controllable nanostructures for electrospun fibers with an emphasis on the understanding of structure formation and explore their unique applications. Specifically, this dissertation can be divided into two areas. The first part is related to superhydrophobic or "self-cleaning" surfaces. This has been a hot research area due to the wide applications of such materials. Electrospun fibers were first discovered in this dissertation to have sufficient surface roughness for superhydrophobic effect. In contrast to many conventional superhydrophobic surfaces, those composed of electrospun fibers are flexible, breathable and free-standing. It has been demonstrated that superhydrophobic fabrics can be made by either electrospinning a hydrophobic material or applying post-treatment to electrospun mats (e.g. through initiated chemical vapor deposition). Based on an understanding of the role of fibrous structure to create a surface of suitable topology, different strategies have been invented to enhance the superhydrophobic property and its robustness by carefully designing the external nanostructures of individual fibers using various methods such as layer-by-layer assembly. Other functionalities such as transparency and fluorescence were successfully incorporated into superhydrophobic surfaces. In particular, superhydrophobic fibrous membranes with structural colors as those displayed by some beautiful butterfly wings were produced. Besides making superhydrophobic materials from the externally nanostructured fibers, internally nanostructured electrospun fibers were also developed through the microphase separation of cylindrically confined block copolymer systems.(cont.) This is the second part of this dissertation. Continuous nanofibers with long range order internal structure were obtained by two-fluid coaxial electrospinning in which the desired block copolymer is encapsulated as the core component within a polymer shell having a high glass transition temperature (Tg), followed by proper thermal annealing of the fibers. Various interesting, unusual and sometimes unprecedented self-assembly structures of block copolymers under cylindrical confinement have been observed. Based on quantitative analyses, the confinement was found to affect both phase type and fundamental domain sizes of the block copolymer. These internally nanostructured fibers have both practical and fundamental intellectual importance. For example, these nanofibers have unique potential for applications in optics, photonics, drug delivery, and other uses because of their small diameter, unique internal structure, and continuous filamentary nature.by Minglin Ma.Ph.D

Core-shell Hydrogel Microcapsules for Improved Islets Encapsulation

Islets microencapsulation holds great promise to treat type 1 diabetes. Currently used alginate microcapsules often have islets protruding outside capsules, leading to inadequate immuno-protection. A novel design of microcapsules with core–shell structures using a two-fluid co-axial electro-jetting is reported. Improved encapsulation and diabetes correction is achieved in a single step by simply confining the islets in the core region of the capsules

Culturally and Linguistically Diverse School Environments – Exploring the Unknown

Abstract: Australian education policies aspire to meet the unique needs of all students including those from linguistically diverse backgrounds; however, a first step in achieving this aim is clear identification of such students. Many children from previous migrant families and new arrivals to Australia come from homes where at least one parent speaks a language other than English. This exploratory research utilises survey and interview responses from students and staff in five Queensland state high schools. Results showed that 79.5% of the 2,484 students surveyed were from English-only homes with only 10.5% classified as having English as Another Language/Dialect. The remaining 10% were also from bi/multilingual homes. While early identification of bi/multilingual students allows for appropriate assessment and strategic support, staff responses highlighted limited preservice training and/or understanding of how to support these students. Only 4.7% of staff surveyed had received any academic training, and 10.4% professional development, about teaching students from diverse backgrounds who, in the surveyed schools, accounted for 20.5% of the student cohort