Child Effects on Parental Negativity: The Role of Heritable and Prenatal Factors.

This study examined two possible mechanisms, evocative gene-environment correlation and prenatal factors, in accounting for child effects on parental negativity. Participants included 561 children adopted at birth, and their adoptive parents and birth parents within a prospective longitudinal adoption study. Findings indicated child effects on parental negativity, such that toddlers' negative reactivity at 18 months was positively associated with adoptive parents' over-reactive and hostile parenting at 27 months. Furthermore, we found that child effects on parental negativity were partially due to heritable (e.g., birth mother [BM] internalizing problems and substance use) and prenatal factors (e.g., BM illicit drug use during pregnancy) that influence children's negative reactivity at 18 months. This study provides critical evidence for "child on parent" effects.

Single-layer metamaterial bolometer for sensitive detection of low-power terahertz waves at room temperature.

This study demonstrates a metamaterial bolometer that can detect terahertz (THz) waves by measuring variations in electrical resistance. A metamaterial pattern for enhanced THz waves absorption and a composite material with a high temperature coefficient of resistance (TCR) are incorporated into a single layer of the bolometer chip to realize a compact and highly sensitive device. To detect the temperature change caused by the absorption of the THz waves, a polydimethylsiloxane mixed with carbon black microparticles is used. The thermosensitive composite has TCR ranging from 1.88%/K to 3.11%/K at room temperature (22.2-23.8°C). In addition, a microscale metamaterial without a backside reflector is designed to enable the measurement of the resistance and to enhance the sensitivity of the bolometer. The proposed configuration effectively improves thermal response of the chip as well as the absorption of the THz waves. It was confirmed that the irradiated THz waves can be detected via the increment in the electrical resistance. The resistance change caused by the absorption of the THz waves is detectable in spite of the changes in resistance originating from the background thermal noise. The proposed metamaterial bolometer could be applied to detect chemical or biological molecules that have fingerprints in the THz band by measuring the variation of the resistance without using the complex and bulky THz time-domain spectroscopy system.

Terahertz optical characteristics of two types of metamaterials for molecule sensing.

We investigate spectral responses of two different terahertz (THz) metamaterials of double split ring resonator (DSRR) and the nano slot resonator (NSR) for molecule sensing in low concentration. Two different resonant frequencies of DSRR can be controlled by polarization angle of incident THz beam. For comparison of THz optical characteristics, two NSRs were made as showing the same resonant frequencies as DSRR's multimode. The monosaccharide molecules of glucose and galactose were detected by these two types of metamaterials matching the resonant frequencies in various concentration. NSR shows higher sensitivity in very low concentration range rather than DSRR, although the behavior was easily saturated in terms of concentration. In contrast, DSRR can cover more broad concentration range with clear linearity especially under high quality factor mode in polarization of 67.5 degree due to the Fano resonance. THz field enhancement distributions were calculated to investigate sensing performance of both sensing chips in qualitative and quantitative manner.

Measurement of beam profiles by terahertz sensor card with cholesteric liquid crystals.

We demonstrate a sensor card with cholesteric liquid crystals (CLCs) for terahertz (THz) waves generated from a nonlinear crystal pumped by a table-top laser. A beam profile of the THz waves is successfully visualized as color change by the sensor card without additional electronic devices, power supplies, and connecting cables. Above the power density of 4.3 mW/cm2, the approximate beam diameter of the THz waves is measured using the hue image that is digitalized from the picture of the sensor card. The sensor card is low in cost, portable, and suitable for various situations such as THz imaging and alignment of THz systems.

Fabrication of polarization-dependent reflective metamaterial by focused ion beam milling.

By focused ion beam milling, we fabricated near-IR reflective metamaterials consisting of nano-aperture arrays. Optimum parameters of ion beam current and accelerating voltage in the fabrication process are obtained. Nano-apertures constituting reflective metamaterial are successfully milled, and possess a reflective resonance in the near-IR spectral range. With a double-split-ring resonator structure for the nano-aperture, the intensity reflection at resonance is rendered polarization dependent. It is found that the point group symmetry of the nano-aperture array determines the amount of anisotropy in the intensity reflection. Finite-difference time-domain simulation was adopted to identify details of nano-aperture metastructures transferred from nano-aperture patterns by the focused ion beam milling.

Anisotropic change in THz resonance of planar metamaterials by liquid crystal and carbon nanotube.

THz metamaterials are employed to examine changes in the meta-resonances when two anisotropic organic materials, liquid crystal and carbon nanotubes, are placed on top of metamaterials. In both anisotropic double split-ring resonators and isotropic four-fold symmetric split-ring resonators, anisotropic interactions between the electric field and organic materials are enhanced in the vicinity of meta-resonances. In liquid crystal, meta-resonance frequency shift is observed with the magneto-optical coupling giving rise to the largest anisotropic shift. In carbon nanotube, meta-resonance absorptions, parallel and perpendicular to nanotube direction, experience different amount of broadening of Lorentzian oscillator of meta-resonance. Investigation reported here opens the application of metamaterials as a sensor for anisotropic materials.

Cryogenic temperature measurement of THz meta-resonance in symmetric metamaterial superlattice.

A symmetric metamaterial superlattice is introduced accommodating a high Q-factor trapped mode. THz time-domain spectroscopy is employed to measure the transmission spectra, identifying the excitation of trapped and open-modes in the meta-resonances. A finite-difference-time- domain calculation showed that the trapped mode excitation is from the cancelation of current densities among the nearest-neighboring meta-particles. A cryogenic temperature THz measurement is carried out to examine the temperature dependence of resonance characteristics of meta-resonances. At low temperatures, the temperature-independent radiative damping is dominant for the open-mode, while the Q-factor of the trapped mode is determined by the temperature-dependent phonon scattering and temperature-independent defect scattering with the radiative damping significantly suppressed. When compared with the room temperature measurement, a 16% increase in Q-factor is observed for the trapped mode, while a 7% increase for the open-mode at the cryogenic temperature.

Optical switching of near infrared light transmission in metamaterial-liquid crystal cell structure.

A metamaterial-liquid crystal cell structure is fabricated with the metamaterial as one of the liquid crystal alignment layers. Nano-sized double-split ring resonator in the metamaterial accommodates two distinct resonances in the near infrared regime. By adopting an azo-nematic liquid crystal in a twisted nematic liquid crystal cell structure, a photo-isomerization process is utilized to achieve an optical switching of light transmissions between two resonances. A single device of the metamaterial-liquid crystal cell structure has a potential application in the photonic switching in optical fiber telecommunications.

Polarization angle control of coherent coupling in metamaterial superlattice for closed mode excitation.

A superlattice structure of planar metamaterial is fabricated, where the orientation of double-split ring resonators is altered in a periodic way. A time-domain terahertz transmission spectrum shows an enhanced Q-factor resonance appears when a closed mode is selectively excited by angular tuning of polarization direction. The polarization-angle selective resonance in metamaterial superlattice has a potential application in the selective field enhancement for spectroscopy.

Hemoglobin induces colon cancer cell proliferation by release of reactive oxygen species.

AIM: To study whether hemoglobin could amplify colon cancer cell proliferation via reactive oxygen species (ROS) production. METHODS: Colon cancer cell line HT-29 was grown in the conventional method using RPMI1640 media. The viability of the cells was measured using the colorimetric MTT [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] assay after adding hemoglobin. We determined reactive oxygen species levels to be indicators of oxidative stress in HT 29 cell lines with and without hemoglobin and/or 5-fluorouracil (5-FU), 5'-deoxy-5-fluorouridine (5-DFUR) using fluorometric dichlorofluorescin diacetate (DCFH-DA) assay. RESULTS: Cellular proliferation was increased with hemoglobin in a concentration-dependent manner. A significant increment on ROS levels was found in HT 29 cells following hemoglobin incubation. The cytotoxic effects of 5-FU and 5-DFUR were significantly blunted by administration of hemoglobin. There was a slight increase of peroxiredoxin 1, superoxide dismutase 1 concentration according to different hemoglobin concentrations. CONCLUSION: Hemoglobin has a cellular proliferative effect on HT-29 colon cancer cell line by production of ROS. Also, hemoglobin abates cytotoxic effects of chemotherapeutic agents such as 5-FU and 5-DFUR.

Microstructure of a poled surface-relief grating and its electro-optic response.

The microstructure of a poled surface-relief grating of an azobenzene side-chain polymer film is investigated. From the in situ monitoring of diffraction efficiency and second-harmonic generation, as well as dynamic-contact electrostatic force microscopy images, the point group symmetry of C2nu is identified. The polarization-dependent electro-optic measurement of the reflected diffraction order further confirms the optically biaxial structure of the poled surface-relief grating.