The intensity attenuation of a high-power laser is a frequent task in the measurements of optical science. Laser intensity can be attenuated by inserting an optical element, such as a partial reflector, polarizer or absorption filter. These devices are, however, not always easily applicable, especially in the case of ultra-high-power lasers, because they can alter the characteristics of a laser beam or become easily damaged. In this study, we demonstrated that the intensity of a laser beam could be effectively attenuated using a random pinhole attenuator (RPA), a device with randomly distributed pinholes, without changing the beam properties. With this device, a multi-PW laser beam was successfully attenuated and the focused beam profile was measured without any alterations of its characteristics. In addition, it was confirmed that the temporal profile of a laser pulse, including the spectral phase, was preserved. Consequently, the RPA possesses significant potential for a wide range of applications.

Although the cardiovascular benefits of an increased urinary potassium excretion have been suggested, little is known about the potential cardiac association of urinary potassium excretion in patients with chronic kidney disease. In addition, whether the cardiac association of urinary potassium excretion was mediated by serum potassium levels has not been studied yet. We reviewed the data of 1633 patients from a large-scale multicentre prospective Korean study (2011–2016). Spot urinary potassium to creatinine ratio was used as a surrogate for urinary potassium excretion. Cardiac injury was defined as a high-sensitivity troponin T ≥ 14 ng/l. OR and 95 % (CI for cardiac injury were calculated using logistic regression analyses. Of 1633 patients, the mean spot urinary potassium to creatinine ratio was 49·5 (sd 22·6) mmol/g Cr and the overall prevalence of cardiac injury was 33·9 %. Although serum potassium levels were not associated with cardiac injury, per 10 mmol/g Cr increase in the spot urinary potassium to creatinine ratio was associated with decreased odds of cardiac injury: OR 0·917 (95 % CI 0·841, 0·998), P = 0·047) in multivariate logistic regression analysis. In mediation analysis, approximately 6·4 % of the relationship between spot urinary potassium to creatinine ratio and cardiac injury was mediated by serum potassium levels, which was not statistically significant (P = 0·368). Higher urinary potassium excretion was associated with lower odds of cardiac injury, which was not mediated by serum potassium levels.

Genetic factors have been suggested to be one of the determinants of the variation of left ventricular (LV) structure and function. However, the heritability range of LV structure varies across studies and the influence of genetics on LV function is not well established, especially in Asian populations. Study subjects were 1,642 healthy Korean adults from 426 families, consisting of 298 pairs of monozygotic twins, 62 pairs of dizygotic twins, one set of triplets, 567 siblings, and 354 parents. LV structure and function were measured by M-mode and 2D echocardiography, and conventional and tissue Doppler imaging (TDI). Pairwise intra-class correlations for various familial relationships and heritability were estimated for LV structure and function. The heritability of LV mass, LV ejection fraction (LVEF), left atrial volume index, the ratio between early and late diastolic velocity of mitral inflow (E/A ratio), and the ratio between early diastolic velocity of mitral inflow and early diastolic mitral annular velocities (E/Ea ratio) was 0.44, 0.27, 0.44, 0.25, and 0.33, respectively. Bivariate genetic analysis showed that LV structural and functional traits had significant genetic correlations with cardiovascular risk factors. Additive genetic correlation (ρG) of LV mass with body mass index, systolic blood pressure, and high density lipoprotein cholesterol were 0.49, 0.42, and -0.15 respectively. LVEF (ρG = 0.33) and left atrial volume index (ρG = 0.24) also had a significant genetic correlation with systolic blood pressure. These findings support the theory that genetic factors have significant influence on these traits and necessitate further work to identify the specific genes involved.

We report the microstructures and dielectric properties of Ca1-xSrxCu3Ti4O12 (C1-xSxCTO, 0≤x≤1) ceramics sintered at the various sintering temperatures ranging from 1000 to 1060˚C in air. The linear increase in lattice parameter in C1-xSxCTO (0≤x≤1) ceramics is observable for the full range of substitution. However, the second phases of SrTiO3 and CuO start to occur from the composition of x=0.8, implying that a stoichiometric SrCu3Ti4O12 (SCTO) compound may not exist. While the C0.6S0.4CTO and C0.4S0.6CTiO samples exhibit relatively lower dielectric constant (εr) of ∼40,000 below 1 kHz, the CaCu3Ti4O12 (CCTO) and SCTO show the extremely high εr values of ~120,000 and ∼180,000, respectively. Complex impedance (Z*) and modulus (M*) spectroscopy revealed that the capacitance (C) and resistivity (ρ) values of grain boundary in all samples are much higher than those of grains.

Single-crystalline rock-salt PbS nanowires (NWs) were synthesized using three different routes; the solvothermal, chemical vapor transport, and gas-phase substitution reaction of pre-grown CdS NWs. They were uniformly grown with the [100] or [110], [112] direction in a controlled manner. In the solvothermal growth, the oriented attachment of the octylamine (OA) ligands enables the NWs to be produced with a controlled morphology and growth direction. As the concentration of OA increases, the growth direction evolves from the [100] to the higher surface-energy [110] and [112] directions. In the synthesis involving chemical vapor transport and the substitution reaction, the use of a lower growth temperature causes the higher surface-energy growth direction to change from [100] to [110]. We fabricated field effect transistors using single PbS NW, which showed intrinsic p-type semiconductor characteristics for all three routes. For the PbS NW with a thinner oxide layer, the carrier mobility was measured to be as high as 10 cm2V−1s−1.

Pure CdSe and Mg-doped CdSe nanocrystal quantum dots were synthesized into the zinc-blende structure at a low temperature by the inverse micelle technique using paraffin oil and oleic acid as surface capping agents. The ripening behavior of the nanocrystals was monitored using the red shift in ultraviolet (UV)-visible light absorption peaks, and their size variation was estimated using the so-called, quantum confinement theory. The Lifshitz–Slyozov–Wagner (LSW) kinetics analyses were performed based on the variation in size according to the ripening temperature and time period. The activation energy (Q) and reaction rate constant (Ko) were determined for the ripening reaction using Arrhenius-type plots. The kinetics analyses reveal that the volume diffusion through the liquid-phase solution is the governing mechanism for the ripening of both nanocrystals. The Mg-doped CdSe nanocrystals showed enhanced ripening kinetics due to the low activation energy for the volume diffusion.

Recently, low molecular organic non-volatile memories have been developed as a next generation of non-volatile memory because of nano-meter device-feature size and nano-second access and store-time. We developed a non-volatile memory fabricated with the device structure of Al/ α-NPD/Al nano-crystals surrounded by Al2O3/α-NPD/Al, where α-NPD is N,N'-bis(1-naphthyl)-1,1'biphenyl4-4”diamine. One layer of Al nano-crystals with ∼20 nm-width ∼20 nm length was uniform produced between α-NPD layers, confirmed by 1.2MV high voltage transmission-electron-microscope. This device showed Vth of 3.0 V, Vprogram of 4.3 V, and Verase of 6.3 V. Particularly, this device exhibited an excellent non-volatile memory behavior performing the bi-stability (Iprogrm/Ierase) of >1×102, program/erase cycles of >1×105 and multi-levels. In addition, previous reports about low molecular organic non-volatile memories have showed a bad reproducible memory characteristic. However, this issue was completely solved via isolating Al nano-crystals embedded in α-NPD by O2 plasma oxidation. The uniformity of Vth, Vp, and Ve were 9.91%, 6.94% and 7.92%, respectively. Furthermore, the effect of buffer or barrier layer on non-volatile memory characteristics was investigate to examine the control ability for Vth, Vp, and Ve. The 0.5-nm LiF showed a barrier layer behavior suppressing the bi-stability of non-volatile memory. Otherwise, 15-nm CuPc exhibited a buffer layer behavior enhancing the bi-stability of nonvolatile memory.

Due to a rapid shrinkage in memory devices, backned of the line process experiences great difficulties, especially Al metallization. Furthermore, there is a continuous demands in low line resistance in order to promote device performances. In this article, Al damascene process is proposed as compared to Al patterning process, which suffers from inherent pattering issue at a fine pitch under 70nm. The most difficulties in the development of Al damascene process were to form a stable and void free Al in fine trench and to obtain scratch and corrosions free Al surface. In this study, 50nm beyond fill was successfully achieved by “bottom up growth” of CVD Al. For the process, CVD Al by using Methylpyrroridine Alane (MPA) precursor was deposited on a stacked film of CVD TiN and PVD TiN as a wetting layer, which was followed by PVD Al and reflow, then the Al surface was polished with colloidal silica based slurry.

In addition, electrical property of Al scheme and W scheme was compared with damascene pattern, along with which we demonstrated that around 36% decrease in parasitic capacitance is achievable by decrease of metal line height from 3500A to 1000A on simulation test implying that device performance could be enhanced.

Pt/Ti/SiO2/Si substrates seeded by SBT nanoparticles (∼60–80 nm) were used to enhance the phase formation kinetics of Sr0.7Bi2.4Ta2O9 (SBT) thin films. The volume fractions of Aurivillius phase formation obtained through quantitative x-ray diffraction (Q-XRD) analyses showed highly enhanced kinetics in seeded SBT thin films. The Avrami exponents were determined as ∼1.4 and ∼0.9 for unseeded and seeded SBT films, respectively, which reveals different nucleation modes. By using Arrhenius–type plots the activation energy values for the phase transformation of unseeded and seeded SBT thin films were determined to be ∼264 and ∼168 kJ/mol, respectively. This gives a key reason to the enhanced kinetics in seeded films. Microstructural analyses on unseeded SBT thin films showed formation of randomly oriented needle-like crystals, while those on seeded ones showed formation of domains comprised of directionally grown worm-like crystals.

Sr0.7Bi2.4Ta2O9 (SBT) thin films were deposited on Pt/Ti/SiO2/Si substrates with and without a seed layer of ∼40 nm thickness using sol-gel and spin coating methods. The influence of seed layer on the phase formation characteristics of SBT thin films was investigated using x-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. Formation of pyrochlore as well as Aurivillius phase was observed in both the unseeded and seeded SBT films heated at 740°C. However, it was revealed that Aurivillius phase formation was enhanced in seeded SBT thin films and pyrochlore phase formation was highly suppressed. In this study, two possible mechanisms for the suppression of pyrochlore phase formation were proposed from the perspectives of activation energy difference for Aurivillius and pyrochlore phase formation and Bi-ion diffusion to pyrochlore phase.

The crystallization kinetics of Sr0.7Bi2.3Ta2O9 (SBT) and 0.7SrBi2Ta2O9–0.3Bi3TiTaO9 (SBT-BTT) thin films formed by the sol-gel and spin coating techniques were studied. Phase formation and crystal growth are greatly affected by the film composition and crystallization temperature. Isothermal kinetic analysis was performed on the x-ray diffraction results of the thin films heated in the range of 730 to 760 °C at 10 °C intervals. Activation energy and Avrami exponent values were determined for the fluorite-to-Aurivillus phase transformation. A reduction of approximately 51 kJ/mol in activation energy was observed for the SBT-BTT thin films, and an Avrami exponent value of approximately 1.0 was obtained for both the SBT and SBT-BTT. A comparison is made, and the possible crystallization mechanism is discussed.

The kinetics of the formation of PbTiO3 at the PbO/TiO2 interface has been analyzed. The flux of Pb2+ and O2− ions through the PbTiO3 layer was used to derive the kinetics equation for the formation of the PbTiO3 phase. On the basis of the parabolic growth kinetics of the PbTiO3 interlayer, the reaction rate constant (k) for PbTiO3 formation was determined as a function of the average diffusion coefficient of the Pb2+ ions (DPb2+). By employment of the data from diffusion couple experiments and the free energy values for the formation of the PbTiO3 phase () into the present kinetics equation, DPb2+ in the PbTiO3 interlayer was calculated with respect to the corresponding temperature. The activation energy for diffusion (Q) and the diffusion constant (D0) of Pb2+ ions in the PbTiO3 layer could be evaluated from the Arrhenius plot of DPb2+.

Strontium bismuth tantalate (SBT) having composition of Sr0.7Bi2.4Ta2O9 has been prepared through sol-gel method using their corresponding metal alkoxides as precursors. Seeded SBT powder was prepared by the addition of 5 wt.% of nanometer sized SBT particles to the sol followed by pyrolysis. By applying non-isothermal kinetic analysis to the DTA results, activation energy values for the unseeded and seeded samples were determined. Enhanced crystallization kinetics was observed for the seeded one and the activation energy for the aurivillius phase formation was found to be 318 kJ/mol, while 375 kJ/mol for the unseeded. The Avrami exponent values for the seeded and unseeded were found to be 2.80 and 0.96 respectively.

Phase formation characteristics of Sr0.7Bi2.4Ta2O9 (SBT) powder, synthesized via sol-gel and pyrolysis process, was investigated by using thermal analysis. Each of the two exotherms, appearing in differential thermal analysis (DTA) scan curves, was identified as crystallization of fluorite phase and transformation of fluorite to aurivillius phase, respectively by using x-ray diffraction (XRD). By applying non-isothermal kinetic analyses to the DTA results, activation energy values for the formation of fluorite and aurivillius phases were determined as 192 and 375 kJ/mol, respectively and Avrami exponent values for each reaction were determined as 0.91 and 0.96, respectively. These activation energy and Avrami exponent values were discussed in detail to understand phase formation mechanism in SBT system.

A direct synthesis of carbon nanotubes (CNTs) on substrates by chemical vapor deposition (CVD) is one of highly probable routes to reach their application to field emission displays. Several stringent requirements are prerequisite for this purpose, including low temperature growth below 600°C to engage glass substrates and large area deposition for practical use. This study carried out synthesis of CNTs by thermal CVD on glass substrates at temperatures as low as 500~550°C. CNTs were grown by thermal decomposition of CO and H2 gases at an atmospheric pressure for different thickness of Invar (an Fe-Ni-Co alloy ) catalytic layers. The growth of CNTs was strongly correlated with preparation of catalytic layers. The diameters and heights of as-grown CNTs increased as the catalytic layers became thicker from 2nm to 30nm. Measurements of the field emission properties of CNTs showed that the threshold electric fields were lowered with increasing thickness of catalytic layers. A uniform electron emission was observed over a large area of 150 × 150mm2, with high emission currents and high brightness.

A detail kinetic analysis was performed on the PbTiO3 phase formation reaction occurring via PbO-TiO2 diffusion couple experiments. The diffusion model of Pb2+ and O2− ions was used to derive the kinetics equation of PbTiO3 phase formation reaction. From the parabolic kinetics between the thickness of PbTiO3 layer and time, the reaction rate constant for PbTiO3 formation was determined to be a function of the average diffusion coefficient of Pb2+ ions. By substituting the diffusion couple experimental results into the present kinetics equation, average diffusion coefficient values of Pb2+ ions in PbTiO3 layer were calculated according to temperature values. The activation energy value for the diffusion of Pb2+ ions was estimated for PbTiO3 formation using Arrhenius plot and the equation for the diffusion coefficient of Pb2+ ions was determined.

The crystallization kinetics of SBT and SBT-BTT thin films formed by sol-gel technique on Pt substrate was studied. Phase formation and crystal growth are greatly affected by the film composition and crystallization temperature. Isothermal kinetics analysis was performed on x-ray diffraction (XRD) patterns of the thin films heated in the range 730 to 760° at 10° intervals. Activation energy and Avrami exponent values were determined for the fluorite to Aurivillus phase formation. A reduction of ∼55 kJ/mol in activation is observed for the SBT-BTT system. A comparison has been made and the possible crystallization mechanism is discussed.