High Potential of Aerosol-Made 3D Graphene-Based Composites for Enhanced Energy Storage.

Recently, many researchers have developed advanced energy storage and energy conversion systems to address the increased demand for energy resources. The performance of these electrochemical energy storage and conversion devices depends considerably on the properties of their unique electrode materials. Among electrode materials, graphene (GR) has attracted much attention due to its unique properties of high flexibility, a large specific surface area, and superior electric conductivity rates that are well-suited to energy storage systems. Specifically, aerosol-made 3D GR composites are known to be more resistant to compressive forces such as paper balls owing to their stronger and harder compressive tolerance levels and higher and more stable surface areas compared to 2D GR sheets. These unique properties of 3D GR composites result in enhanced electrochemical performances for energy storage systems. This review focuses on recent studies of aerosol-made 3D GR-based composites for energy storage systems such as supercapacitors, lithium-ion batteries, and sodium-ion batteries.

K2Ti6O13 Nanoparticle-Loaded Porous rGO Crumples for Supercapacitors.

One-dimensional alkali metal titanates containing potassium, sodium, and lithium are of great concern owing to their high ion mobility and high specific surface area. When those titanates are combined with conductive materials such as graphene, carbon nanotube, and carbon nanofiber, they are able to be employed as efficient electrode materials for supercapacitors. Potassium hexa-titanate (K2Ti6O13, KTO), in particular, has shown superior electrochemical properties compared to other alkali metal titanates because of their large lattice parameters induced by the large radius of potassium ions. Here, we present porous rGO crumples (PGC) decorated with KTO nanoparticles (NPs) for application to supercapacitors. The KTO NP/PGC composites were synthesized by aerosol spray pyrolysis and post-heat treatment. KTO NPs less than 10 nm in diameter were loaded onto PGCs ranging from 3 to 5 µm. Enhanced porous structure of the composites was obtained by the activation of rGO by adding an excessive amount of KOH to the composites. The KTO NP/PGC composite electrodes fabricated at the GO/KOH/TiO2 ratio of 1:3:0.25 showed the highest performance (275 F g-1) in capacitance with different KOH concentrations and cycling stability (83%) after 2000 cycles at a current density of 1 A g-1.

Hierarchical networks of redox-active reduced crumpled graphene oxide and functionalized few-walled carbon nanotubes for rapid electrochemical energy storage.

Crumpled graphene is known to have a strong aggregation-resistive property due to its unique 3D morphology, providing a promising solution to prevent the restacking issue of graphene based electrode materials. Here, we demonstrate the utilization of redox-active oxygen functional groups on the partially reduced crumpled graphene oxide (r-CGO) for electrochemical energy storage applications. To effectively utilize the surface redox reactions of the functional groups, hierarchical networks of electrodes including r-CGO and functionalized few-walled carbon nanotubes (f-FWNTs) are assembled via a vacuum-filtration process, resulting in a 3D porous structure. These composite electrodes are employed as positive electrodes in Li-cells, delivering high gravimetric capacities of up to ∼170 mA h g(-1) with significantly enhanced rate-capability compared to the electrodes consisting of conventional 2D reduced graphene oxide and f-FWNTs. These results highlight the importance of microstructure design coupled with oxygen chemistry control, to maximize the surface redox reactions on functionalized graphene based electrodes.

Flexible graphene-based chemical sensors on paper substrates.

Graphene-based, flexible NO(2) sensors on paper substrates exhibited an immediate response (32-39%) once exposed to 200 ppm NO(2) gas under a strain of 0.5%. Chemical vapor deposition-grown graphene with a supporting poly(methyl methacrylate) layer was transferred onto paper substrates, followed by formation of two electrodes using silver paste. Current-voltage characteristics and dynamic sensing response were obtained under both relaxed and strained conditions. We demonstrate a facile method without complex photo-lithography and high vacuum processes for fabricating graphene-based flexible NO(2) sensors on paper substrates with high sensing response.

Deafness and cochlear implants: a deaf scholar's perspective.

During the past 3 decades, cochlear implants have dramatically influenced Deaf education and the Deaf Community. They have also served as catalysts for discord between some members of the Deaf Community and advocates of the technology. In this article, I do not intend to support either side of the spoken English versus sign language debate. Instead, I will discuss ethical and practical issues related to cochlear implants. More specifically, I will address the nature and notion of deafness and the purpose of Deaf education. Although many authors have discussed these issues, they have mostly done so from the perspective of hearing scholars and the hearing parents of deaf children. It is important to recognize that understanding deafness and the experience of life from a Deaf individual's perspective has important implications for further educational policy and practice.

The qualitative similarity hypothesis.

Evidence is presented for the qualitative similarity hypothesis (QSH) with respect to children and adolescents who are d/Deaf or hard of hearing. The primary focus is on the development of English language and literacy skills, and some information is provided on the acquisition of English as a second language. The QSH is briefly discussed within the purview of two groups of cognitive models: those that emphasize the cognitive development of individuals and those that pertain to disciplinary or knowledge structures. It is argued that the QSH has scientific merit with implications for classroom instruction. Future research should examine the validity of the QSH in other disciplines such as mathematics and science and should include perspectives from social as well as cognitive models.

The effect of cilostazol on stent thrombosis after drug-eluting stent implantation.

BACKGROUND AND OBJECTIVES: Placement of drug-eluting stents (DES) can be complicated by stent thrombosis; prophylactic antiplatelet therapy has been used to prevent such events. We evaluated the efficacy of cilostazol with regard to stent thrombosis as adjunctive antiplatelet therapy. SUBJECTS AND METHODS: A total of 1,315 patients (846 males, 469 females) were prospectively enrolled and analyzed for the frequency of stent thrombosis. Patients with known risk factors for stent thrombosis, except diabetes and acute coronary syndrome, were excluded from the study. All patients maintained antiplatelet therapy for at least six months. To evaluate the effects of cilostazol as another option for antiplatelet therapy, triple antiplatelet therapy (aspirin+clopidogrel+cilostazol, n=502) was compared to dual antiplatelet therapy (aspirin+clopidogrel, n=813). Six months after stent placement, all patients received only two antiplatelet drugs: treatment either with cilostazol+aspirin (cilostazol group) or clopidogrel+aspirin (clopidogrel group). There were 1,033 patients (396 in cilostazol group and 637 in clopidogrel group) that maintained antiplatelet therapy for at least 12 months and were included in this study. Stent thrombosis was defined and classified according to the definition reported by the Academic Research Consortium (ARC). RESULTS: defined and classified according to the definition reported by the Academic Research Consortium (ARC). RESULTS: During follow-up (561.7+/-251.4 days), 15 patients (1.14%) developed stent thrombosis between day 1 to day 657. Stent thrombosis occurred in seven patients (1.39%) on triple antiplatelet therapy and four patients (0.49%) on dual antiplatelet therapy (p=NS) within the first six months after stenting. Six months and later, after stent implantation, one patient (0.25%) developed stent thrombosis in the cilostazol group, and three (0.47%) in the clopidogrel group (p=NS). CONCLUSION: During the first six months after DES triple antiplatelet therapy may be more effective than dual antiplatelet therapy for the prevention of stent thrombosis. However, after the first six months, dual antiplatelet treatment, with aspirin and cilostazol, may have a better cost benefit ratio for the prevention of stent thrombosis.