Asymmetric memory for birth language perception versus production in young international adoptees.

Adults who as children were adopted into a different linguistic community retain knowledge of their birth language. The possession (without awareness) of such knowledge is known to facilitate the (re)learning of birth-language speech patterns; this perceptual learning predicts such adults' production success as well, indicating that the retained linguistic knowledge is abstract in nature. Adoptees' acquisition of their adopted language is fast and complete; birth-language mastery disappears rapidly, although this latter process has been little studied. Here, 46 international adoptees from China aged four to 10 years, with Dutch as their new language, plus 47 matched non-adopted Dutch-native controls and 40 matched non-adopted Chinese controls, undertook across a two-week period 10 blocks of training in perceptually identifying Chinese speech contrasts (one segmental, one tonal) which were unlike any Dutch contrasts. Chinese controls easily accomplished all these tasks. The same participants also provided speech production data in an imitation task. In perception, adoptees and Dutch controls scored equivalently poorly at the outset of training; with training, the adoptees significantly improved while the Dutch controls did not. In production, adoptees' imitations both before and after training could be better identified, and received higher goodness ratings, than those of Dutch controls. The perception results confirm that birth-language knowledge is stored and can facilitate re-learning in post-adoption childhood; the production results suggest that although processing of phonological category detail appears to depend on access to the stored knowledge, general articulatory dimensions can at this age also still be remembered, and may facilitate spoken imitation.

Potential of a sensitive uric acid biosensor fabricated using hydroxyapatite nanowire/reduced graphene oxide/gold nanoparticle.

In this study, a ternary nanocomposite consisting of gold nanoparticles (AuNPs), hydroxyapatite (HAP) nanowires, and reduced graphene oxide (rGO) is synthesized by a simple one-step hydrothermal method, which is used to modify glassy carbon electrode (GCE) for detecting uric acid. The nanocomposite is characterized through various methods such as scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. Electrochemical measurements of the modified GCE are performed in a conventional three-electrode system. Experimental results show that the obtained HAP nanowire and rGO are mixed homogeneously, and the AuNPs are deposited into this matrix. The GCE modified by the nanocomposites have superior electrocatalytic activities for uric acid. The peak current intensities of UAO (uricase)/HAP-rGO/AuNPs sensing system linearly increase as the uric acid concentration increases substantially in a range of 1.95 × 10-5 to 6.0 × 10-3 M (R2 = .9943), with a detection limit of 3.9 × 10-6 M (S/N = 3) and analytical sensitivity of 13.86 mA/M. The biosensor performs well in determining uric acid concentration in human urine samples.