Hyperspectral push-broom imager using a volume Bragg grating as an angular filter.

A hyperspectral push-broom imager has been designed, constructed, and tested. The narrow angular selectivity of a weakly index modulated volume Bragg grating is utilized to replace the objective lens, slit, and collimating lens of a conventional slit-based hyperspectral push-broom imager. The imager comprises a dispersion grating, an angular filter grating, a focusing lens, and an image sensor. The imager has a field of view (FOV) of 17 degrees in the spatial direction, a spectral range from 400 nm to 900 nm, and a spectral resolution of 2.1 nm. The acquired hyperspectral data cubes are presented, and the influence of wavelength-dependent incident angle errors is analyzed.

Simultaneous Enhancement of the Mechanical Properties, Performance and Insensitivity of an Energetic Elastomeric Polyurethane Binder by Kinetically Grafting Reactive Spiranes.

A series of robust energetic polyurethane binders was developed by in situ grafting reactive spiranes to achieve the migration-resistant processing aid and compensate for the energy output. The reactive grafting spiranes (RGSs), bearing two highly ring-strained spiranes, were synthesized sequentially to provide a promising ring strain energy up to a maximum value of 290 kJ mol-1. The thermodynamic compatibility of the RGS with uncured glycidyl azido polymer (GAP) was studied quantitatively by analyzing the glass transition temperature of their blendings. The reactivity study of the catalyst-free click reaction with respect to spacer-dependent species was amplified by tracing the extent of the reaction and measuring the activation energy. The faster reactivity of propargyl species was evident from two experimental approaches, which were verified further by theoretical predictions. Interestingly, the energy gap difference in the frontier molecular orbitals agreed well with the difference in activation energy between the two types of spacer-dependent species. The mechanical and thermochemical enhancements of GAP-based polyurethane with RGS were basically gained from those highly ring-strained moieties.

Humidity-Sensing Chipless RFID Tag with Enhanced Sensitivity Using an Interdigital Capacitor Structure.

An eight-bit chipless radio frequency identification tag providing humidity sensing and identification information is proposed. A compact, enhanced-sensitivity resonator based on an interdigital capacitor (IDC) structure is designed for humidity sensing, whereas seven electric-field-coupled inductor capacitor (ELC) resonators are used for identification information. These eight resonators are placed in a two-by-four array arrangement. A step-by-step investigation for the effect of varying the number of elements and array configuration on the resonant frequency and radar cross-section (RCS) magnitude of the IDC resonator is conducted. The RCS value of the resonant peak frequency for the IDC resonator increases as the number of array elements placed nearby increases due to the mutual coupling among the elements, and the increase in the RCS value becomes larger as the number of arrays increases in the vertical direction. Polyvinyl alcohol (PVA) is coated on the IDC-based resonator at a thickness of 0.02 mm. A non-reflective temperature and humidity chamber is fabricated using Styrofoam, and the relative humidity (RH) is varied from 50% to 80% in 10% intervals at 25 °C in order to measure a bistatic RCS of the proposed tag. The humidity sensing performance of the IDC resonator in the proposed tag is measured by the shift in the resonant peak frequency and the RCS value, and is compared with a single ELC resonator. Experiment results show that when RH increased from 50% to 80%, the sensitivities of both the resonant peak frequency and the RCS value of the IDC resonator were better than those of the ELC resonator. The variation in the RCS value is much larger compared to the resonant peak frequency for both IDC and ELC resonators. In addition, the resonant peak frequency and RCS value of the PVA-coated IDC-based resonator change, whereas those of the other seven resonators without a PVA coating do not change.

Effect of Hollow Silica Microspheres on Compressive and Dynamic Mechanical Properties of Hydroxyl-Terminated Polybutadiene-Based Polyurethane Composites.

Porous polyurethane composites containing hollow silica microspheres were prepared by one-step bulk polymerization to study cyclic compressive and dynamic mechanical properties of the composites. Cyclic compression testing was conducted to record the stress versus strain curves during the loading and unloading cycles and in order to study the compressive behavior and time-dependent recovery of the composites. Effect of frequency on the dynamic mechanical properties of the composites was also evaluated using dynamic mechanical analysis. Master curves were constructed based on time-temperature superposition principle in order to show long-term dynamic mechanical behavior of the composites.

Synthesis and Characterization of Reactive Energetic Plasticizers for Poly(glycidyl azide-co-tetramethylene glycol)-Based Polyurethane Binders.

Two reactive energetic plasticizers, 3-((2,2-dinitropropoxy)methoxy)prop-1-yne and 4-((2,2-dinitropropoxy)methoxy)but-1-yne which can react with an azido-containing poly(glycidyl azide-co-tetramethylene glycol) prepolymer by cupper-free 1,3-dipolor cycloaddition ("Click") reaction, were synthesized and characterized, in order to investigate their plasticizing performance and catalyst-free 1,3-dipolar cycloaddition reactivity on energetic polyurethane binders. Two reactive energetic plasticizers showed better plasticizing performance than commercial energetic plasticizers. In the reactivity point of view, 3-((2,2-dinitropropoxy)methoxy)prop-1-yne exhibited higher Click reactivity than 4-((2,2-dinitropropoxy)methoxy)but-1-yne. Two synthesized plasticizers were found to fulfill the requirements for use as reactive energetic plasticizers.

Study on Cyclic Compressive and Dynamic Mechanical Properties of Porous Polyurethane Composites Prepared with Hollow Silica Microspheres.

Porous polycaprolactone-based polyurethane composites containing hollow silica microspheres were synthesized by one-step bulk polymerization. The effects of incorporated hollow silica microspheres on the cyclic compressive and dynamic mechanical properties of the composites were examined. Cyclic compression testing was carried out to record the accumulated stress versus strain profiles during 100 continuous loading and unloading cycles and to study the compressive behavior and time-dependent recovery of the composites. The effects of frequency on the dynamic mechanical properties of the composites was also investigated using a dynamic mechanical analyzer. Cole-Cole and Wicket plots were drawn to check the validity of the time-temperature supposition of the composites in the temperature and frequency ranges considered. Master curves of the composites were constructed based on the time-temperature superposition principle to obtain the long-term dynamic mechanical behavior of the composites.

Molecular Weight Effects of Biscarbazole-Based Hole Transport Polymers on the Performance of Solid-State Dye-Sensitized Solar Cells.

The leakage and volatilization of liquid electrolytes limit the commercialization of dye-sensitized solar cells (DSCs). As solid-state (ss) hole-transporting materials, free from leakage and volatilization, biscarbazole-based polymers with different molecular weights (PBCzA-H (21,200 g/mol) and PBCzA-L (2450 g/mol)) were applied in combination with additives to produce ssDSCs. An ssDSC with PBCzA-H showed a better short-circuit current (Jsc), open-circuit voltage (Voc), and fill factor (FF) than a device with PBCzA-L, resulting in 38% higher conversion efficiency. Compared to the PBCzA-L, the PBCzA-H with a higher molecular weight showed faster hole mobility and larger conductivity, leading to elevations in Jsc via rapid hole transport, Voc via rapid hole extraction, and FF via lowered series and elevated shunt resistances. Thus, it is believed that PBCzA-H is a useful candidate for replacing liquid electrolytes.

Synthesis and Characterization of Monosaccharide-Containing 2-(α-D-mannopyranosyloxy)Ethyl Methacrylate as a Surface Modifier for Hydrogels.

We introduce a hydrophilic monosaccharide-containing 2-(α-D-mannopyranosyloxy)ethyl methacrylate (ManEMA) in this study to achieve more extended and comfortable wear silicone hydrogel contact lenses by increasing water content. Molecular structure of ManEMA contains a monosaccharide moiety with four hydroxyl groups, which provide a strong interaction with water. Therefore, the ManEMA-containing hydrogels are expected to have high water content. The structure of synthesized ManEMA is confirmed by 1H and 13C NMR spectroscopy. Contact lenses containing silicone polymers are coated with a monosaccharide-containingManEMA monomer with the help of plasma treatment and the use of 3-(trimethoxylsilyl)propyl methacrylate to provide an increased hydrophilicity. The feasibility of ManEMA as a surface modifier of silicone lenses is investigated in terms of water content and surface energy.

Metal organic framework UiO-66 and activated carbon composite sorbent for the concurrent adsorption of cationic and anionic metals.

A composite sorbent for the simultaneous removal of both Hg2+ and SeO32- from aqueous media was produced from the solvothermal synthesis of a zirconium metal organic framework, UiO-66, in the presence of activated carbon. The composite sorbent has a large surface area of 1051 m2 g-1 with crystalized porous structures and has strong thermal stability up to 600 °C. The contaminant uptake of the sorbent follows a Langmuir adsorption isotherm with maximum sorption capacity of 205 mg g-1 and 168 mg g-1 for Hg2+ and SeO32-, respectively. Scanning electron microscopy-energy dispersive spectroscopy results show that the Se regions overlap exclusively with Zr-rich regions suggesting that SeO32- adsorption depends entirely on the exposed UiO-66 surface. In addition, X-ray photoelectron spectroscopy spectra of Se 3d and Hg 4f showed the association of SeO32- and Hg2+ on the UiO-66 and carbon surfaces, respectively. The sorbent could facilitate the development of a single process for the simultaneous removal of cationic Hg and anionic Se as well as other similar ionic metals with opposite charges from aqueous media.

Porous Silicone Polymeric Composites Filled with Hollow Silica Particles: Thermal Conductivity, Thermal Stability and Mechanical Properties.

Porous silicone composites containing different types and volume fractions of hollow silica particles (HSPs) were prepared and characterized in terms of thermal insulation performance, thermal stability, and tensile and dynamic mechanical properties. The comparative study on measured and theoretical thermal conductivity of porous silicone/HSP composites was performed. Dependence of shell thickness, defined as the ratio (η) of internal (ri) to outer (r0) radius, and volume fraction (Φ) of HSPs on the thermal insulation performance of composites was predicted theoretically by Felske model. Tensile properties and dynamic mechanical measurements showed the incorporation of HSPs led to mechanical reinforcement in the silicone composites. Theh Guth and Gold equation showed mechanical reinforcement of porous silicone/HSP composites was primarily due to the hydrodynamic effect of HSPs in the silicone matrix at low HSP contents (Φ < 0.5).

Synthesis and Plasticization Performance of Reactive Plasticizers Utilizing Catalyst-Free Azide-Alkyne Click Reaction.

Three different reactive plasticizers (RPs), such as bicyclo[2.2.1]heptan-2-yl-methyl propiolate (NPA), bicyclo[2.2.1]heptan-2-yl-methyl butynoate (NBA), and bicyclo[2.2.1]heptan-2-yl-methyl pent-4-ynoate (NPEA), were synthesized in good yield and characterized. Thermal studies revealed that RPs had low glass transition temperature (Tg < -90 °C) and were thermally stable up to 210 °C. The plasticization performance of RPs to GAP prepolymer was evaluated in terms of miscibility, viscosity reduction, and azide-alkyne Click reactivity. Results made them good candidate as RPs for GAP-based polymers.

Mechanical and Thermal Insulation Properties of Porous Silica/Polyurethane Composites.

Porous hydroxyl-terminated polybutadiene-based polyurethane (HPU) composites containing various hollow glass microspheres (HGMs) up to 75 vol.% were synthesized by one-step bulk polyaddition-type polymerization. An unfilled (non-porous) HPU sample was also prepared as a reference. The thermal conductivity of the HPU/HGM composites, which are considered as a three-phasic material composed of a bulk HPU matrix, silicate thin layer, and pores, could be predicted perfectly by the Felske model. The thermal properties, such as Tg and thermal stability, of the HPU/HGM composites were affected slightly by the addition of HGMs compared to the unfilled HPU. On the other hand, the shell thickness and volume of the HGMs played an important role in determining the mechanical properties of the composites leading to reinforcement with increasing wall thickness and content of HGMs.

Thermal and Mechanical Characterization of Polymeric Foams with Controlled Porosity Using Hollow Thermoplastic Spheres.

Polyurethane (PU) foams with controlled porosity and pore structure are prepared via judicious study on expanding process parameters for thermoplastic expandable microspheres which are compatible with PU synthetic process. Thermal and mechanical properties of PU foams are found to be generally governed by amount of the porosity. Thermal conductivity of PU foams with controlled porosity is measured at 30 °C with transient hot bridge method. The measured thermal conductivity of PU foams is estimated using theoretical models, proving the formation of spherical pore structures of expandable microspheres in PU matrix and serving as an internal porous material.

Reactive Energetic Plasticizers Utilizing Cu-Free Azide-Alkyne 1,3-Dipolar Cycloaddition for In-Situ Preparation of Poly(THF-co-GAP)-Based Polyurethane Energetic Binders.

Reactive energetic plasticizers (REPs) coupled with hydroxy-telechelic poly(glycidyl azide-co-tetrahydrofuran) (PGT)-based energetic polyurethane (PU) binders for use in solid propellants and plastic-bonded explosives (PBXs) were investigated. The generation of gem-dinitro REPs along with a terminal alkyne stemmed from a series of finely designed approaches to not only satisfy common demands as conventional energetic plasticizers, but also to prevent the migration of plasticizers. The miscibility and rheological behavior of a binary mixture of PGT/REP with various REP fractions were quantitatively determined by differential scanning calorimetry (DSC) and rheometer, respectively, highlighting the promising performance of REPs in the formulation process. The kinetics on the distinct reactivity of propargyl vs. 3-butynyl species of REPs towards the azide group of the PGT prepolymer in terms of Cu-free azide-alkyne 1,3-dipolar cycloaddition (1,3-DPCA) was studied by monitoring ¹H nuclear magnetic resonance spectroscopy and analyzing the activation energies (Ea) obtained using DSC. The thermal stability of the finally cured energetic binders with the incorporation of REPs indicated that the thermal stability of the REP/PGT-based PUs was maintained independently of the REP content. The tensile strength and modulus of the PUs increased with an increase in the REP content. In addition, the energetic performance and sensitivity of REP and REP triazole species was predicted.

Synthesis and Thermal Analysis of Nano-Aluminum/Fluorinated Polyurethane Elastomeric Composites for Structural Energetics.

Here we describe the synthesis of polyurethane (PU)-based energetic nanocomposites loaded with nano-aluminum (n-Al) particles. The energetic nanocomposite was prepared by polyurethane reaction of poly(glycidyl azide-co-tetramethylene glycol) (PGT) prepolymers and IPDI/N-100 isocyanates with simultaneous catalyst-free azide-alkyne Click reaction in the presence of n-Al. Initial study carried out with various n-Al/fluorinated PGT blends and demonstrated the potential of fluorinated PGT prepolymer for an energetic PU matrix. Thermal analysis of n-Al/fluorinated PGT-based PU energetic nanocomposite was performed using DSC and TGA.

A Comparative Study of the Epidemiological Aspects of Legionnaires' Disease: Outbreaks in Korea and Japan, 2010 - 2014.

BACKGROUND: In the present study, we compared the epidemiological aspects of Legionnaire' disease (LD) outbreaks in Korea and Japan by analyzing the current state from 2010 to 2014. METHODS: The following factors were analyzed: nationwide cumulative incidence rate (CIR) per 100,000 populations and case-fatality rate in percentage, epidemiological aspects (i.e., case related to gender), male to female morbidity ratio (MFMR), age, seasonality and habitat distribution of LD cases. RESULTS: In total, there were 134 cases of LD with the CIR of 0.05 per 100,000 populations in Korea from 2010 to 2014. During the same period in Japan, there were 4,840 cases of LD with a CIR of 0.76 per 100,000 populations. The CIR in Japan was significantly higher than that in Korea. However, the case-fatality rates were at similar levels (3.0% vs. 5.9%). Moreover, LD affects both sexes differently, accounting for 2.05 and 4.41 of MFMR in Korea and Japan, respectively. In both countries, the incidence mainly occurred among people aged 40 years or older, and peaked in summer (37.3% vs. 33.7% of total cases). Significant differences were observed in the incidence of LD cases between the capital city and county areas in both two countries. These differences in LD risk factors reflect the different influences of reservoir/host with natural or artificial aquatic environments. CONCLUSION: This study provides a quantitative analysis of the epidemiological aspects and risk factors of LD outbreaks in Korea and Japan. We hope this study would be helpful for providing insight on effective future strategies to reduce LD outbreaks.

Comparative Investigation on Thermal Insulation of Polyurethane Composites Filled with Silica Aerogel and Hollow Silica Microsphere.

This paper presents a comparative study on thermal conductivity of PU composites containing open-cell nano-porous silica aerogel and closed-cell hollow silica microsphere, respectively. The thermal conductivity of PU composites is measured at 30 degrees C with transient hot bridge method. The insertion of polymer in pores of silica aerogel creates mixed interfaces, increasing the thermal conductivity of resulting composites. The measured thermal conductivity of PU composites filled with hollow silica microspheres is estimated using theoretical models, and is in good agreement with Felske model. It appears that the thermal conductivity of composites decreases with increasing the volume fraction (phi) when hollow silica microsphere (eta = 0.916) is used.

Thermal Stability and Ablation Behavior of Modified Polydimethylsiloxane-Based Polyurethane Composites Reinforced with Polyhedral Oligomeric Silsesquioxane.

Series of polydimethylsiloxane (PDMS)-based polyurethane (PU)/polyhedral oligomeric silsesquioxane (POSS) composites are prepared using ether or polyether modified diol/polyol PDMS prepolymers, isophorone diisocyanate (IPDI) and either non-reactive or reactive POSS. The effect of POSS incorporated chemically or physically, number of ethylene oxide units and crosslinking on PDMS based PU is investigated in terms of thermal stability and ablation properties. The ablation property is measured using an oxyacetylene torch test, and the ablation rate is evaluated. The results show that POSS molecules make a considerable influence on the ablative resistance, because they act as protective silica forming precursors under oxyacetylene condition. POSS molecules, especially methyl POSS, in PU matrix leads to the formation of densely accumulated spherical silica layers on the top of the ablated surface, resulting in improved ablation resistance.

Trends in the epidemiological aspects and mortality of alcoholic liver disease in Korea in the decade between 2000 and 2009.

BACKGROUND: Alcohol consumption and related alcohol liver disease (ALD) have substantially increased in Korea during the last decade. The objective of this study was to evaluate the trends in the epidemiological aspects and mortality rate (MR) of Korea in the decade between 2000 and 2009. METHODS: The raw data analyzed in this study were obtained from the website of "the ALD" managed by Korea Center for Disease Control and Prevention (KCDC), Korea Public Health Association (KPHA), and statistics website of Statistics Korea. The data analyses were performed using Excel 2007 statistical software (Microsoft Corp., USA). RESULTS: The amount of alcohol-consumption-per-capita-per-year (ACCY) in Korea was 8.38 L in 2000 and 8.54 L in 2009. The most taken alcoholic beverage was soju, followed by beer. There were a total of 1,403 case-fatalities (CF) with an MR of 2.98 per 100,000 populations of ALD in 2000, while a total of 3,588 CF with an MR of 7.21 in 2009 (P < 0.01). The CF and MR of ALD in males were significantly higher than those in females (P < 0.01). In over 40-year-old age groups, the CF and MR were significantly increased (P < 0.01). Moreover, occupational classification revealed that the mistress/students/jobless (MSJ) were the most risky group. The comparison of overall CF and MR of ALD by six key classifications (International Classification of Diseases (ICD)) showed that alcoholic cirrhosis (229 CF and 16.3%) in 2000 tended to be increased in 2009 (2,803 CF and 78.1%), while alcoholic fibrosis and sclerosis (607 CF and 43.3%) in 2000 significantly decreased in 2009 (120 CF and 3.3%), respectively. CONCLUSION: ALD is one of the most severe diseases in Korea, as indicated by its high CF and MR in this study. As over-consumption of alcoholic beverages is relatively common in Korea, more efforts should be made toward prevention of ALD by raising awareness of the risk factors of ALD by public health education.

Synthesis and properties of hydroxyl-terminated polybutadiene-based polyurethanes reinforced with polyhedral oligomeric silsesquioxanes.

Polyurethane/polyhedral oligomeric silsesquioxane (PU/POSS) hybrid composites are prepared by a one-step PU reaction using hydroxyl-terminated polybutadiene (HTPB) prepolymer, isophorone diisocyanate (IPDI) and either non-reactive or reactive POSS molecule. The effect of incorporation of functionalized POSS molecules covalently bonded or physically blended into PU matrix is investigated in terms of mechanical reinforcement and thermal stability of these resulting PU/POSS hybrid composites. PU/POSS hybrid composites prepared with reactive POSS molecules exhibit the mechanical reinforcement while maintaining low glass transition temperataure (T(g)), probably due to the fact that reactive POSS molecules chemically incorporated in PU are aggregated to crystallize, effectively working as a physical crosslinking in PU/POSS hybrid composites. This can be advantageous in that mechanical reinforcement of PU/POSS hybrid composites can be achived without sacrificing the low temperature properties of these composites. However, the contribution of POSS molecules incorporated covalently into PU matrix is virtually absent on the thermal decomposition temperature (T(d,max)) measured using TGA/DTG. Thermal degradation behavior of these hybrid composites in the early stage rather appears to depend preferably on characteristics of POSS molecules incorporated.