Learning a second language in adulthood changes subcortical neural encoding

Second language learning has been shown to impact and reshape the central nervous system, anatomically and functionally. Most of the studies on second language learning and neuroplasticity have been focused on cortical areas, whereas the subcortical neural encoding mechanism and its relationship with L2 learning have not been examined extensively. The purpose of this study was to utilize frequency-following response (FFR) to examine if and how learning a tonal language in adulthood changes the subcortical neural encoding in hearing adults. Three groups of subjects were recruited: native speakers of Mandarin Chinese (native speakers (NS)), learners of the language (L2 learners), and those with no experience (native speakers of foreign languages (NSFL)). It is hypothesized that differences would exist in FFRs obtained from the three language experience groups. Results revealed that FFRs obtained from L2 learners were found to be more robust than the NSFL group, yet not on a par with the NS group. Such results may suggest that in human adulthood, subcortical neural encoding ability may be trainable with the acquisition of a new language and that neuroplasticity at the brainstem level can indeed be influenced by L2 learning

Fermi level alignment by copper doping for efficient ITO/perovskite junction solar cells

Different from band edge alignment, the Fermi level mismatch induced by band bending can manipulate charge collection at the ITO/(CH_3NH_3)_(1−x)Cu_xPbI_3 heterojunctions. In this work, we employed a feasible spin-coating process to prepare copper defect compensation in CH_3NH_3PbI_3. The related work function was shown to shift with the copper doping density by Kelvin probe force microscopy (KPFM). Next, we applied transient surface photovoltage (TSPV) spectroscopy and first-order series reactions simulations to confirm that interface charge recombination at the ITO/perovskite junction can be eliminated through Cu+ doping. Nanoelectric photoconductive AFM analysis showed enhanced charge transfer and a higher photovoltage at the ITO/Cu-perovskite junction. Owing to efficient Fermi level alignment, the ITO/(CH_3NH_3)_(1−x)Cu_xPbI_3/PCBM/Ag devices displayed high power conversion efficiencies of 15.14 ± 0.67% at ambient conditions for inverted perovskite solar cells without any hole transport layer

Fermi level alignment by copper doping for efficient ITO/perovskite junction solar cells

Different from band edge alignment, the Fermi level mismatch induced by band bending can manipulate charge collection at the ITO/(CH_3NH_3)_(1−x)Cu_xPbI_3 heterojunctions. In this work, we employed a feasible spin-coating process to prepare copper defect compensation in CH_3NH_3PbI_3. The related work function was shown to shift with the copper doping density by Kelvin probe force microscopy (KPFM). Next, we applied transient surface photovoltage (TSPV) spectroscopy and first-order series reactions simulations to confirm that interface charge recombination at the ITO/perovskite junction can be eliminated through Cu+ doping. Nanoelectric photoconductive AFM analysis showed enhanced charge transfer and a higher photovoltage at the ITO/Cu-perovskite junction. Owing to efficient Fermi level alignment, the ITO/(CH_3NH_3)_(1−x)Cu_xPbI_3/PCBM/Ag devices displayed high power conversion efficiencies of 15.14 ± 0.67% at ambient conditions for inverted perovskite solar cells without any hole transport layer

Robust 3.7 V-Na2/3_{2/3}[Cu1/3_{1/3}Mn2/3_{2/3}]O2_2 Cathode for Na-ion Batteries

Na-ion batteries (NIBs), which are recognized as a next-generation alternative technology for energy storage, still suffer from commercialization constraints due to the lack of low-cost, high-performance cathode materials. Since our first discovery of Cu$^{3+}$/Cu$^{2+}$ electrochemistry in 2014, numerous Cu-substituted/doped materials have been designed for NIBs. However for almost ten years, the potential of Cu$^{3+}$/Cu$^{2+}$ electrochemistry has been grossly underappreciated and normally regarded as a semielectrochemically active redox. Here, we re-synthesized P2-Na$_{2/3}$[Cu$_{1/3}$Mn$_{2/3}$]O$_2$ and reinterpreted it as a high-voltage, cost-efficient, air-stable, long-life, and high-rate cathode material for NIBs, which demonstrates a high operating voltage of 3.7 V and a completely active Cu$^{3+}$/Cu$^{2+}$ redox reaction. The 2.3 Ah cylindrical cells exhibit excellent cycling (93.1% capacity after 2000 cycles), high rate (97.2% capacity at 10C rate), good low-temperature performance (86.6% capacity at -30$^\circ$C), and high safety, based on which, a 56 V-11.5 Ah battery pack for E-bikes is successfully constructed, exhibiting stable cycling (96.5% capacity at the 800th cycle) and a long driving distance (36 km, tester weight 65 kg). This work offers a commercially feasible cathode material for low-cost, high-voltage NIBs, paving the way for advanced NIBs in power and stationary energy storage applications.Comment: 15 pages, 3 figures, 1 tabl

Two-Dimensional VO₂ Nanosheets with a Controllable Crystalline-Preferred Orientation for High-Performance Zinc-Ion Batteries

Due to the environmental friendliness, cost-effectiveness and inherent safety, rechargeable aqueous zinc ion batteries have attracted much interest as a promising energy storage device. VO2 is one of the most common materials for rechargeable zinc ion batteries. The insertion/extraction of zinc ions within VO2 is highly anisotropic, with different channel sizes along different axes. Therefore, it is quite important to control the orientation of VO2 crystals so as to manipulate the transportation of Zn2+ ions more effectively and sufficiently. Herein, a novel intercalation-type two-dimensional VO2 nanosheet with preferred orientation (PO-VO2) of the c-axis was prepared. Benefitting from the structural merits, the PO-VO2 nanosheets demonstrate an attractive capacity of 511.6 mAh g−1 at a current density of 0.05 A g−1 in a voltage of 0.2–1.6 V, which is obviously better than that of many vanadium oxide-based cathodes reported until now. The PO-VO2//Zn aqueous zinc ion full cell exhibits a high energy density of 290.5 Wh kg−1 at a power density of 38.4 W kg−1 (based on the mass of the VO2 cathode electrode). The outstanding energy storage behavior, together with the facile and affordable synthesis route, endows the PO-VO2 nanosheets with promising applications for aqueous zinc ion batteries

Characteristic of Stimulus Frequency Otoacoustic Emissions: Detection Rate, Musical Training Influence, and Gain Function

Stimulus frequency otoacoustic emission (SFOAE) is an active acoustic signal emitted by the inner ear providing salient information about cochlear function and dysfunction. To provide a basis for laboratory investigation and clinical use, we investigated the characteristics of SFOAEs, including detection rate, musical training influence, and gain function. Sixty-five normal hearing subjects (15 musicians and 50 non-musicians, aged 16–45 years) were tested and analyzed at the probe level of 30 and 50 dB sound pressure levels (SPL) in the center frequency of 1 and 4 kHz in the study. The results indicate that (1) the detection rates of SFOAE are sensitive to the gender, (2) musicians reveal enhanced hearing capacity and SFOAE amplitudes compared with non-musicians, and (3) probe frequency has a significant effect on the compression threshold of SFOAE. Our findings highlight the importance of SFOAE in the clinical hearing screening and diagnosis and emphasize the use of musical training for the rehabilitation enhancement of the auditory periphery and hearing threshold

Defect and doping properties of sliding ferroelectric γ-InSe for photovoltaic applications

Layered van der Waals (vdw) materials have been proposed as light-absorbing materials for photovoltaic applications. InSe is a layered vdw semiconductor with ultra-high carrier mobility, strong charge transfer ability, super deformability, thermoelectricity, and optoelectronic properties. Its γ phase, or γ-InSe, was greatly stabilized by doping recently, which also exhibits sliding ferroelectricity. In this study, we propose that γ-phase InSe (γ-InSe), which was recently synthesized in a high-quality bulk phase, could be an excellent light-absorbing material candidate. Based on the first-principles simulations, bulk γ-InSe is found to possess suitable bandgap, decent absorption, and low effective mass. The investigation of defect properties reveals the major defect types, defect levels, and deep-level defects that could possibly harm the efficiency, and the deep-level defects can be significantly suppressed under Se-rich conditions. In addition, γ-InSe is intrinsically n-type, which can be tuned into weak p-type by Zn and Cd doping. We also identify the defect types of Y and Bi doping, which have been experimentally used to adjust the mechanical property of γ-InSe, and find that Y interstices could play an important role in improving the stiffness of γ-InSe. Our study provides theoretical insights for photovoltaic and other photoelectronic applications based on this interesting ferroelectric layered vdw material