In the emerging era of Internet of Things (IoT), power sources for wireless sensor nodes in conjunction with efficient and secure wireless data transfer are required. Energy harvesting technologies are promising solution toward meeting the requirements for sustainable power sources for the IoT. In this review, we focus on approaches for harvesting stray vibrations and magnetic field due to their abundance in the environment. Piezoelectric materials and piezoelectric–magnetostrictive [magnetoelectric (ME)] composites can be used to harvest vibration and magnetic field, respectively. Currently, such harvesters use modified lead zirconate titanate (or lead-based) piezoelectric materials and ME composites. However, environmental concerns and government regulations require the development of a suitable lead-free replacement for lead-based piezoelectric materials. In the past decade, several lead-free piezoelectric compositions have been developed and demonstrated with promising piezoelectric response. This paper reviews the significant results reported on lead-free piezoelectric materials with respect to high-density energy harvesting, covering novel processing techniques for improving the piezoelectric response and temperature stability. The review of the state-of-the-art studies on vibration and magnetic field harvesting is provided and the results are used to discuss various strategies for designing high-performance energy harvesting devices.

The preparation of transmission electron microscopy (TEM) samples from powders is quite difficult and challenging. For powders with particles in the 1–5 μm size range, it is especially difficult to select an adequate sample preparation technique. Epoxy is commonly used to bind powder, but drawbacks, such as differential milling originating from unequal milling rates between the epoxy and powder, remain. We propose a new, simple method for preparing TEM samples. This method is especially useful for powders with particles in the 1–5 μm size range that are vulnerable to oxidation. The method uses solder as an embedding agent together with focused ion beam (FIB) milling. The powder was embedded in low-temperature solder using a conventional hot-mounting instrument. Subsequently, FIB was used to fabricate thin TEM samples via the lift-out technique. The solder proved to be more effective than epoxy in producing thin TEM samples with large areas. The problem of differential milling was mitigated, and the solder binder was more stable than epoxy under an electron beam. This methodology can be applied for preparing TEM samples from various powders that are either vulnerable to oxidation or composed of high atomic number elements.

To evaluate the appropriateness of the screening strategy for healthcare personnel (HCP) during a hospital-associated Middle East Respiratory Syndrome (MERS) outbreak, we performed a serologic investigation in 189 rRT-PCR–negative HCP exposed and assigned to MERS patients. Although 20%–25% of HCP experienced MERS-like symptoms, none of them showed seroconversion by plaque reduction neutralization test (PRNT).

Infect Control Hosp Epidemiol 2017;38:234–238

This article reviews the application of nanomaterials for radiation shielding to protect humans from the hazards of radiation in space. The focus is on protection from space radiation, including galactic cosmic radiation (GCR), solar particle events (SPEs), and neutrons generated from the interactions of the GCR and SPEs with the intervening matter. Although the emphasis is on protecting humans, protection of electronics is also considered. There is a significant amount of work in the literature on materials for radiation shielding in terrestrial applications, such as for neutrons from nuclear reactors; however, the space environment poses additional and greater challenges because the incident particles can have high charges and extremely high energies. For materials to be considered for radiation shielding in space, they should perform more than just the radiation-shielding function; hence the emphasis is on multifunctional materials. In space, there is also the need for materials to be very lightweight and capable of surviving temperature extremes and withstanding mechanical loading. Nanomaterials could play a significant role as multifunctional radiation-shielding materials in space.

Analytical electron microscopy (AEM) was used to examine the initial interfacial reaction layers between a eutectic Sn–3.5Ag solder and an electroless nickel-immersion gold-plated (ENIG) Cu substrate during reflow at 255 °C for 1 s. AEM confirmed that a thick upper (Au,Ni)Sn2 layer and a thin Ni3Sn4 layer had formed through the reaction between the solder and ENIG. The amorphous electroless Ni(P) plated layer transformed into two P-rich Ni layers. One is a crystallized P-rich Ni layer, and the other is an intermediate state P-rich Ni layer before the crystallization. The crystallized P-rich layer consisted of Ni2P and Ni12P5. A thin Ni2P layer had formed underneath the Ni3Sn4 layer and is believed to be a predecessor of the Ni2SnP ternary phase. A Ni12P5 phase was observed beneath the Ni2P thin layer. In addition, nanocrystalline Ni was found to coexist with the amorphous Ni(P) phase in the intermediate state P-rich Ni layer.

Since 2005, we have been carrying out a precise radial velocity survey of about 190 intermediate-mass (1.5-5 M⊙) G and K giants at Bohyunsan Optical Astronomy Observatory (BOAO) in Korea and Okayama Astrophysical Observatory (OAO) in Japan, which aims to reveal statistical properties of planetary systems around intermediate-mass stars. We have finished the first screening of 120 stars so far and have identified 5 candidates with large periodic radial velocity variations. One of the candidates turned out to be orbited by a brown dwarf mass companion with minimum mass of 37.6 MJup and semimajor axis of 1.71 AU. The primary star has a mass of 3.9 M⊙, which ranks among the most massive stars with substellar companions. Our discovery may support the current view obtained from results of planet searches around intermediate-mass stars that massive substellar companions tend to form around massive stars.

Objectives: The purpose of this study was to examine the diffusion patterns of new medical technologies in Korean hospitals. We also sought to identify critical factors leading to the decision to acquire capital-intensive medical technology. The rationale and timing of magnetic resonance imaging (MRI) acquisitions were retrospectively evaluated according to a “whether, when, and why” paradigm.

Methods: We analyzed data pertaining to 232 hospitals with active medical residency programs. Of these, 185 hospitals owned or leased an MRI unit, and 47 had not acquired units as of June 2004. Data were collected from the Ministry of Health and Welfare, Korean National Statistical Office, and Korean Hospital Association databases, and variables were identified and classified as predisposing, enabling, or reinforcing factors.

Results: The MRI diffusion rate curve was linear for two types of hospital but was S-shaped for tertiary hospitals, which were early adopters of MRI. Significant predictors for MRI adoption included the per capita number of regional physicians (+), total number of existing regional MRI units (−), percentage of the regional population over 65 years of age (+), private ownership of the hospital, presence of a radiology residency program, number of beds (+), and regional per capita taxable income (+).

Conclusions: Diffusion of MRI technology is occurring rapidly across Korean hospitals. The factors affecting MRI adoption in Korea are similar to the factors documented in other countries, namely regional population over age 65, regional income per capita, large hospitals, and teaching hospitals. This study provides baseline information for predicting diffusion patterns of other new and/or expensive medical technologies.

Conventional Ge2Sb2Te5 (GST) was modified by adding up a small amount of SiOx, using co-sputtering technique from multiple targets. The SiOx content was gradually increased by increasing the power applied to SiOx target, up to 8 volume percent. The sheet resistance of SiOx-containing GST exponentially increased, when the room-temperature-deposited samples were annealed at 300 °C. Transmission electron microscopy images revealed that no SiOx particulates were formed, which was confirmed by Gattan image filtering. It was indicated by x-ray diffraction patterns that the grain size of SiOx-containing GST is smaller than normal GST with lattice locally distorted at its crystalline state, suggesting that molecular SiOx is homogeneously distributed throughout the GST matrix. We observed that the crystallization temperature of SiOx-containing GST is gradually elevated by increasing the SiOx content, while the melting point decreased. These observations led to the reset current reduction, which is a critical requirement for the high density PRAM.

(001) oriented (Ba, Sr)TiO3 (BST) thin films were deposited on MgO (001) single crystal substrates by the pulsed laser deposition method. Structural properties of BST films were investigated using X-ray diffractometer. Coplanar waveguide (CPW) device based on BST/MgO layer structure was fabricated by dc sputtering deposition, photolithography and etching process. To study the geometrical factor dependent microwave performance of the CPW phase shifter based on (001) oriented BST film, the CPW devices having various gap and width were fabricated. The microwave dielectric properties of BST CPW phase shifter devices were examined by calculating the scattering parameter obtained using a HP 8510C vector network analyzer with the frequency range 0.5 ∼ 20 GHz at room temperature under the dc bias field of 0 ∼ 40V. The measured return loss and insertion loss at 10 GHz with no dc bias were about -12 ∼ -4 dB and -14 ∼ -3 dB, respectively, which mainly depended on the impedances of the CPW transmission lines. The measured differential phase shift values were about 20 ° ∼ 140 ° at 10 GHz with 40 V dc bias variations, which depended on the gap size.

An ultra-low temperature (< 200°C) polycrystalline silicon (poly-Si) film is fabricated for the plastic substrate application using inductively coupled plasma chemical vapor deposition (ICP-CVD) and excimer laser annealing. The precursor active layer is deposited using the SiH4/He mixture at 150°C (substrate). The deposited silicon film consists of crystalline component as well as hydrogenated amorphous component. The hydrogen content in the precursor layer is less than 5 at%. The grain size of the precursor active silicon film is about 200nm and it is increased up to 500nm after excimer laser irradiation.