Poly(vinylidene fluoride)/zinc oxide smart composite material

This work aimed at fabrication and electromechanical characterization of a smart material system composed of electroactive polymer and ceramic materials. The idea of composite material system is on account of complementary characteristics of the polymer and ceramic for flexibility and piezoelectric activity. Our preliminary work included Polyvinylidene Fluoride (PVDF) as the flexible piezoelectric polymer, and Zinc Oxide (ZnO) as the piezoelectric ceramic brittle, but capable to respond strains without poling. Two alternative processes were investigated. The first process makes use of ZnO fibrous formation achieved by sintering PVA/zinc acetate precursor fibers via electrospinning. Highly brittle fibrous ZnO mat was dipped into a PVDF polymer solution and then pressed to form pellets. The second process employed commercial ZnO nanopowder material. The powder was mixed into a PVDF/acetone polymer solution, and the resultant paste was pressed to form pellets. The free standing composite pellets with electrodes on the top and bottom surfaces were then subjected to sinusoidal electric excitation and response was recorded using a fotonic sensor. An earlier work on electrospun PVDF fiber mats was also summarized here and the electromechanical characterization is reported

Exciton Dynamics of Colloidal Semiconductor Quantum Well Stacks

Colloidal semiconductor nanoplatelets (NPLs) have recently emerged as a new class of colloidal nanocrystals. NPLs are quasi two-dimensional nanocrystals having atomically flat surfaces and have unique properties such as narrow photoluminescence (PL) emission (similar to 10 nm) and giant oscillator strength. NPLs can be self-assembled into stacks. These are one-dimensional superstructures that can contain tens or hundreds of NPLs in one chain

Efficacy of preheated chelating agents on calcium ion removal from instrumented root canals

The heating of chelating agents such as EDTA increases dentin wettability by decreasing surface tension. However, the calcium ion release effect of preheated chelating agents in instrumented root canals has not yet been mentioned. In this s

Anomalous Spectral Characteristics of Ultrathin sub-nm Colloidal CdSe Nanoplatelets

We demonstrate high quantum yield broad photoluminescence emission of ultrathin sub-nanometer CdSe nanoplatelets (two-monolayer). They also exhibit polarization-characterized lateral size dependent anomalous heavy hole and light/split-off hole absorption intensities.Comment: Published in Conference on Lasers and Electro-Optics (CLEO): Science and Innovations 2017, San Jose, CA, USA, 14-19 May 2017 (2 pages, 3 figures

CdSe/CdSe1-xTex Core/Crown Heteronanoplatelets: Tuning the Excitonic Properties without Changing the Thickness

Here we designed and synthesized CdSe/CdSe1-xTex core/crown nanoplatelets (NPLs) with controlled crown compositions by using the core-seeded-growth approach. We confirmed the uniform growth of the crown regions with well-defined shape and compositions by employing transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. By precisely tuning the composition of the CdSe1-xTex crown region from pure CdTe (x = 1.00) to almost pure CdSe doped with several Te atoms (x = 0.02), we achieved tunable excitonic properties without changing the thickness of the NPLs and demonstrated the evolution of type-II electronic structure. Upon increasing the Te concentration in the crown region, we obtained continuously tunable photoluminescence peaks within the range of similar to 570 nm (for CdSe1-xTex crown with x = 0.02) and similar to 660 nm (for CdSe1-xTex crown with x = 1.00). Furthermore, with the formation of the CdSe1-xTex crown region, we observed substantially improved photoluminescence quantum yields (up to similar to 95%) owing to the suppression of nonradiative hole trap sites. Also, we found significantly increased fluorescence lifetimes from similar to 49 up to similar to 326 ns with increasing Te content in the crown, suggesting the transition from quasi-type-II to type-II electronic structure. With their tunable excitonic properties, this novel material presented here will find ubiquitous use in various efficient light-emitting and-harvesting applications

Coronary Angiography Utilization and Costs for Coronary Artery Bypass Graft Surgery Patients in Turkey

INTRODUCTION: To assess excess use of coronary angiography prior to coronary artery bypass graft surgery and its association with mortality, health care costs, and hospital quality in Turkey. METHODS: Using Turkish National Health Insurance Data (2009–2011) that included patients who underwent cardiac surgery, coronary angiography utilization was identified. Propensity score matching was used to compare survival rates and annual health care costs of patients in a coronary angiography excess-use group (>1 angiogram) and in a standard-therapy group (1 angiogram). The empirical Bayesian approach was used to combine mortality and hospital volume for quality index. The relationship between hospital quality and excess use of coronary angiography was assessed using Chi-squared tests. RESULTS: Out of 20,126 patients identified, 7.27% of patients underwent excessive coronary angiography procedures (excess-use group), with an average annual cost at 9.7% higher than those who had a single angiography (standard-therapy group; P < 0.01). Operational mortality associated with excessive use was significantly higher as well (7.4% versus 5.4%, P < 0.02). There exists variation in the use of coronary angiography across cities and hospitals. Patients who underwent cardiac surgery in high-quality hospitals were less likely to have excessive angiography use than those in low-quality hospitals (7.0% versus 9.5%, P < 0.01). CONCLUSION: In Turkey, excess use of coronary angiography prior to coronary artery bypass graft surgery is associated with higher operational mortality, higher expenditures, and lower hospital quality

A Comparison of high viscosity and low viscosity bone cement vertebroplasty for severe osteoporotic vertebral compression fractures

Introduction: Our aim in this clinical trial was to compare the safety and efficacy of highviscosity cement (HVC) with low-viscosity cement (LVC) for the treatment of osteoporotic vertebrae fractures in terms of pain, functional capacity and cement leakage in the percutaneous vertebroplasty procedure (PVP). Methods: From March 2013 to February 2015, 76 patients with vertebrae compression fracture who were admitted into hospital and treated with PVP were reviewed. Pre- and postoperative clinical characteristics of each patient were obtained by using The Visual Analog Scale (VAS) score to evaluate back pain, Oswestry Disability Index (ODI) as a functional assessment. Cement leakage,injected cement volume and the complications assessed due to medical records. Results: VAS and ODI scores improved (P0.05).Paravertebral cement leakage was significantly higher in the LVC group (P<0.05). Pulmonary cement embolism was also significantly higher in LVC group (P<0.05). Conclusion: HVC had lower complication rates with similar clinical results in the comparison with LVC.Publisher's Versio

Microscopic and molecular detection of Nosema spp. in honeybees of Turkey

International audienceAbstractIn this study, we aimed to determine the prevalence of Nosema spp. in honeybees of Turkey. For this aim, adult honeybee (Apis mellifera) samples were collected from 1621 colonies within 95 apiaries located in 22 provinces of Turkey. Samples were examined microscopically. In case of positivity, spore identification was done by multiplex PCR. At the end of microscopic examination, Nosema spp. spores were detected in 7 out of 22 provinces (31.8 %), and 16 out of 95 colonies (16.8 %) that represent 1621 colonies. According to PCR results, 1 out of 16 isolates (6.25 %) was Nosema apis, and 15 out of 16 isolates (93.75 %) were Nosema ceranae. The result of our study indicated that N.ceranae is the dominant species in Turkey

Cane sign: sciatic neuropathy appearance in magnetic resonance imaging

We present a patient with idiopathic sciatic neuropathy with demonstrative magnetic resonance imaging findings

Orientation-Controlled Construction of Superstructures of Atomically-Flat Nanocrystals: Pushing the Limits of Ultra-Thin Colloidal Gain Media

We propose and demonstrate a method for the construction of highly uniform, multilayered, orientation-controlled superstructures of CdSe/CdZnS core/shell colloidal nanoplatelets (NPLs) using bi-phase liquid interface. These atomically-flat nanocrystals are sequentially deposited, all face-down onto a solid substrate, into slabs having monolayer-precise thickness and excellent homogeneity over several tens of cm2 areas. Owing to the near-unity surface coverage and film uniformity of this deposition technique, amplified spontaneous emission (ASE) is observed from an uncharacteristically thin colloidal film having only 6 layers of NPLs, which corresponds to a mere 42 nm thickness. Furthermore, systematic studies of optical gain properties of these NPL superstructures constructed having precise numbers of NPL layers tuned from 6 to 15 revealed the reduction in the gain threshold with the increasing number of NPL monolayers, along with a continuous spectral shift in the position of the ASE peak (by ~18 nm). These observations can be well explained by the variation of the optical field confinement factor with the NPL waveguide thickness and propagation wavelength. This work demonstrates the possibility of fabricating thickness-tunable, large-area three-dimensional superstructures made of NPL building blocks, which can be additively constructed one monolayer at a time. The proposed technique can also be extended to build hybrid NPL films of mixed orientations and allow for precise large-area device engineering.Comment: 23 pages, 4 figure