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This study aimed to investigate the alterations in brain networks in patients with Alzheimer’s disease (AD) and mild cognitive impairment (MCI) based on a population-specific brain template. Previous studies on AD brain networks using graph theory rarely adopted brain templates specific for certain ethnicities. In this study, patients were divided into 3 groups: AD (n = 24), MCI (n = 27), and healthy controls (HCs, n = 33), and all of the subjects are Chinese. Functional brain networks were constructed for each group based on a Chinese brain template using resting-state functional magnetic resonance imaging (rs-fMRI) data; several graph metrics were calculated. Graph metrics with significant differences after false discovery rate (FDR) correction were analyzed with respect to correlations with four neuropsychological test scores: Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Activities of Daily Living (ADL), and Clinical Dementia Rating (CDR), which assessed the subjects’ cognitive functions and ability to engage in ADL. Graph metrics including assortativity coefficient, nodal degree centrality, nodal clustering coefficient, nodal efficiency, and nodal local efficiency of the frontal gyrus and cerebellum were significantly altered in AD and MCI compared with HC. Several graph metrics were significantly correlated with cognitive function and the ability to engage in daily activities. The findings suggest that altered graph metrics in the frontal gyrus may reflect brain plasticity, and that patients with MCI may have unique graph metric alterations in the cerebellum. Future graph analysis studies on functional brain networks in AD and MCI based on population-specific brain atlases for particular ethnicities may prove valuable.

N-type Mg2Si single crystal ingot has been successfully grown by the Vertical Bridgman technique. The Hall Effect measurement at RT revealed a moderate Hall mobility (~ 446 cm2/Vs), electrical resistivity (~ 1.4 Ω. cm) and carrier density (~1016 cm−3) for the grown crystal. The J-V characteristics of the fabricated Au/n-Mg2Si Schottky junction and Au/Ag-doped-p-type-Mg2Si/n-type-Mg2Si/Ag pn-junction diode showed better diode behavior with higher rectifying ratio in comparison with the same reported junctions. Analysis of the experimental forward J-V characteristics of our fabricated diodes based on the thermionic emission (TE) model demonstrated that our Schottky and pn-junction Mg2Si diode exhibited much lower series resistance in comparison with the survey data, confirming that precise polishing of Mg2Si surfaces with an oil-based diamond greatly improved the contact with the evaporated metal, enabling lower interfacial resistance between the evaporated metal and Mg2Si wafer. In addition, the manufactured Mg2Si pn-junction photodiode showed a clear photoresponsivity in the wavelength range from 0.95 to 1.8 µm with a maximum zero-biased photoresponse of 14 mA/W at 1.4 µm and a photon energy threshold of approximately 0.66 eV. These results indicate that our diode is promising to detect the SWIR light in the wavelength range from 0.95 to 1.8 µm.

Ca3TaAl3Si2O14 (CTAS) single crystal is attracting much attention for high temperature sensor applications due to its high electrical resistivity and excellent piezoelectric properties. However, it is a big challenge to grow high quality CTAS single crystals. In this work, its growth conditions are optimized. Crack- and inclusion-free crystals are grown, achieving even a high quality single crystal with a width over 2 in. In addition, the temperature dependence of electro-elastic properties is systematically studied. This crystal presents a high thermal stability of structure and electro-elastic properties. The dielectric loss is less than 3% from room temperature to 650 °C. Therefore, CTAS single crystal is promising for high temperature sensor applications.

The catangasite Ca3TaGa3Si2O14 (CTGS) single crystal is considered to be a promising self-frequency-doubling material for visible lasers. In this work, a CTGS single crystal with Yb-doping was successfully grown by the Czochralski method for the first time. The as-grown crystal showed yellowish coloration. The temperature dependent thermal properties, such as thermal expansion, specific heat, thermal diffusivity and thermal conductivity, were systematically investigated. The anisotropy of thermal expansion is rather small. Furthermore, its thermal conductivity is comparable to those well-known self-frequency-doubling laser crystals. In laser operation, a maximum continuous wave output power of 4.2 W at the wavelength of 1047 nm was obtained under the output coupler of 5%. These characteristics are very beneficial to laser applications.

Paper-based supercapacitors have attracted more and more attention for high electrochemical performance. However, most of them adopt sandwiched structure. Here, we prepared planar polypyrrole (PPy) coated paper-based supercapacitors by applying simple laser carving assisted method. The planar device showed a significant performance improvement (13.9 mF/cm2) compared to the sandwiched device (12.3 mF/cm2). In addition, by adjusting the polymerization time of pyrrole, the device capacity can be further increased to 87.4 mF/cm2. We firmly believed that the laser carving assisted method has a significant role in promoting the development of flexible planar electronic devices.

High quality colorless Ca 3 TaGa 3−x Al x Si 2 O 14 (CTGAS) single crystals are successfully grown by the Czochralski technique within the full solid solution range. The influence of Al content on the electrical resistivity, dielectric and piezoelectric properties is systematically investigated for the first time at room temperature, as well as a function of temperature up to 700 °C. With the increase of Al content the resistivity, the electromechanical coupling factor k 12 and the piezoelectric coefficient d 11 increase, while the dielectric permittivity e 11 T / e 0 decreases. CTGAS single crystals exhibit a very low dielectric loss ( 10 Ω cm at 400 °C for all samples, i.e. more than two orders of magnitude higher than that of the considered material La 3 Ta 0.5 Ga 5.5−x Al x O 14 . Present results indicate that, among the langasite family, Ca 3 TaAl 3 Si 2 O 14 is at present the most promising crystal for high temperature sensor applications, since it exhibits the highest resistivity and a good piezoelectric response.

In this work the partial substitution of Ca by Sr in the known langasite single crystal Ca3TaAl3Si2O14 is investigated from the point of view of crystal growth in order to improve the piezoelectric properties. For it, a (SrxCa1-x)3TaAl3Si2O14 (SCTAS) single crystal with x = 0.25 was grown by the Czochralski method. The grown crystal was strongly faceted, highly transparent, and of a high crystalline quality, as indicated by a full width at half maximum of the X-ray rocking curve as small as 31 arcsec. On the other hand, the crystal exhibited a high resistivity, with a value over 1010 Ω cm at 400 °C. Temperature dependent piezoelectric measurements confirmed the effective enhancement of the d11 piezoelectric coefficient at any temperature, while maintaining the dielectric loss below 1% up to 600 °C. Therefore, SCTAS exhibits superior properties compared with other piezoelectric materials for high temperature applications.

La 3 Ta 0.5 Ga 5.5-x Al x O 14 (LTGA) is a piezoelectric crystal from the langasite family which presents advantageous properties for high temperature sensor applications. It possesses a high piezoelectric constant and its structure remains stable up to 1500 °C. In this work, a LTGA single crystal has been grown by using the Czochralski technique under N 2 atmosphere with 1% O 2 . The high crystalline quality of grown crystal is confirmed by the 26 arcsec FWHM of X-ray rocking curves. High temperature X-ray diffraction measurements indicate the absence of phase transitions up to 1300 °C. The thermal properties of the crystal, including thermal expansion, specific heat, thermal diffusivity and thermal conductivity, are investigated as a function of temperature. The average thermal expansion coefficients are α a = 8.48 × 10 −6 K −1 and α c = 6.32 × 10 −6 K −1 . The thermal conductivities along the a and c axes at 50 °C are 1.2 and 2.0 W m −1 K −1 , respectively. The resistivity of grown crystal decreases from 4 × 10 10 to 2 × 10 5 Ω cm between 200 and 900 °C. The measured piezoelectric coefficient d 11 , electromechanical coupling factor k 12 and corresponding mechanical quality factor Q at room temperature are 6.94 pC/N, 17% and 12,000, respectively.

For the full benefit of the silicon chip industry and to further extend the photoresponse cut-off wavelength of the current Si photodetectors beyond 1100 nm, high-performance silicon-compatible Mg2Si/Si n-p photodiodes are constructed on the bulk silicon wafer by magnetron sputtering and post-annealing sequential processes. The results show that the annealing period appreciably affects microstructure, crystallite size, and roughness of the Mg2Si film sputtered on glass substrates and silicon wafers. Meanwhile, the fabricated Mg2Si/Si n-p photodiodes demonstrate clear rectifying behavior and evident spectral response characteristics in the wavelength domain from 0.8 to 1.35 μm, with a maximum room temperature zero-bias response of 0.1, 0.15, 0.86, and 0.47 A/W at 1.05 μm for the annealing periods of 10, 20, 40, and 60 min, respectively. The photoresponse cut-off wavelength of the fabricated Mg2Si/Si n-p photodiodes is 1.35 μm; however, the photosensitive cut-off of the commercially available Hamamatsu Si photodiode is 1.25 μm. The fabricated Mg2Si/Si n-p photodiodes at RTA period of 40 min reveal spectral response of longer cut-off wavelength and higher intensity near the photon energy threshold compared to the Hamamatsu Si photodiode. In this context, the fabricated photodiodes in this study offer huge potentials to develop high-performance silicon-compatible photodiodes for efficiently sensing the infrared light in the wavelength domain from 0.8 to 1.35 μm.

A Nd:(Lu x Gd 1− x ) 3 Ga 5 O 12 (Nd:LGGG) crystal with dimensions of Ф 26×14 mm 3 was successfully grown by the Czochralski (Cz) method. The effective segregation coefficients of the Nd and Lu ions in the crystal were measured to be 0.50 and 1.32, respectively. The thermal properties of the crystal, including the average linear thermal expansion coefficient, specific heat and thermal diffusion coefficient, were measured, and the thermal conductivity was calculated. The Judd–Ofelt theory was applied to calculate the spectral parameters of the crystal. All the properties show that the Nd:LGGG crystal is a promising material for laser applications.