A novel whole-cell biocatalyst with high allylic alcohol-oxidizing activities was screened and identified as Yokenella sp. WZY002, which chemoselectively reduced the C=O bond of allylic aldehydes/ketones to the corresponding α,β-unsaturated alcohols at 30°C and pH 8.0. The strain also had the capacity of stereoselectively reducing aromatic ketones to ( S )-enantioselective alcohols. The enzyme responsible for the predominant allylic/benzyl alcohol dehydrogenase activity was purified to homogeneity and designated YsADH (alcohol dehydrogenase from Yokenella sp.), which had a calculated subunit molecular mass of 36,411 Da. The gene encoding YsADH was subsequently expressed in Escherichia coli , and the purified recombinant YsADH protein was characterized. The enzyme strictly required NADP(H) as a coenzyme and was putatively zinc dependent. The optimal pH and temperature for crotonaldehyde reduction were pH 6.5 and 65°C, whereas those for crotyl alcohol oxidation were pH 8.0 and 55°C. The enzyme showed moderate thermostability, with a half-life of 6.2 h at 55°C. It was robust in the presence of organic solvents and retained 87.5% of the initial activity after 24 h of incubation with 20% (vol/vol) dimethyl sulfoxide. The enzyme preferentially catalyzed allylic/benzyl aldehydes as the substrate in the reduction of aldehydes/ketones and yielded the highest activity of 427 U mg ⁻¹ for benzaldehyde reduction, while the alcohol oxidation reaction demonstrated the maximum activity of 79.9 U mg ⁻¹ using crotyl alcohol as the substrate. Moreover, kinetic parameters of the enzyme showed lower K _m values and higher catalytic efficiency for crotonaldehyde/benzaldehyde and NADPH than for crotyl alcohol/benzyl alcohol and NADP ⁺ , suggesting the nature of being an aldehyde reductase.

A simple mass producible uncooled thermoelectric infrared microsensor has been designed and fabricated. To improve the cost-efficiency, an advanced micromachining process, which combines wet anisotropic pre-etching and XeF₂ dry isotropic post-etching, is adopted for the sensor fabrication. The wet anisotropic pre-etching removes bulk silicon from back-side and forms a thin silicon membrane for device fabrication, the XeF₂ dry isotropic post-etching undercuts silicon membrane and releases the microstructure. Experimental results show that the sensor with advanced micromachining exhibits a two times higher responsivity and detectivity than the sensor with only XeF₂ front-side etching. In air at room temperature, the sensor with advanced micromachining has a responsivity of 71.57 V W^-1, noise equivalent power of 0.64 nW Hz^-1/2, detectivity of 6.21×10⁷ cm Hz^1/2 W^-1 and a time constant of 13.2 ms. The effect of back-side etch window size on sensor performance is also characterized by finite-element method simulation.

We present the novel 3D wafer-level vacuum packaging technology for MEMS, which only needs two masks and is realized by Au-Si eutectic bonding with a low-resistivity Si Cap wafer. Wherein, Au-Si bonding pads and rings are formed to accomplish vertical interconnects and a vacuum package respectively. Applied to resonators with two typical substrate wafers of Si and Glass, this 3D package structure has further gone through the systemic characterizations. Specifically, the high-reliable mechanic strengths of device packages are revealed from Au-Si bonding strengths measured as about 20 MPa in tensile tests. Based on analyzing parasitic capacitance networks in device packages, the feed-through effect in resonance tests can be effectively relieved by grounding on each Si layer in device package structures (i.e. the parasitic capacitance reduced from the level of pF to fF). By resonance tests, it is found that increasing the degassing duration (30 min $\to 60$ min $\to 100$ min) is beneficial for improving package vacuum degrees as well as consistencies (69% within 4–30 kPa $\to 88$ % within 0.6-1.2 kPa $\to 85$ % within 0.6-0.8 kPa), and hermetic package yields (73% $\to 86$ % $\to 100$ %). Besides, device packages are verified to have good long-term stability by monitoring quality factor variations in 6 months. Overall, this proposed 3D packaging technology has extensive application prospects in various MEMS devices due to its inherently-simple process, low capacitive feed-through effect, and fine package performances. Also, test results provide instructions on the realization of low-parasitic-capacitance signal interfaces and the optimization of wafer-level vacuum package processes.

The control of acoustic waves on a micro-scale is a critical issue in the development of micro-acoustic devices. In this paper, we demonstrate a locally resonant phononic crystal (PNC) for the control of acoustic waves on a micro-scale. The locally resonant phononic crystal is realized by periodically arranging cylindrical stubs on a silicon plate in a square lattice. Two types of acoustic microwaveguides, i.e., straight waveguide and mirrored “Z” shape waveguide, are designed based on the micro-phononic crystal. Numerical simulation shows that acoustic waves with frequencies in the bandgap range are compelled to propagate along the waveguides. Experimental results also confirm that the locally resonant PNC could effectively control the propagation of acoustic waves with frequencies in the bandgap range. The locally resonant phononic crystal in this paper is believed to be an ideal metamaterial for the acoustic wave control on a micro-scale.

Driven by ever-growing demands on 3D integration, various state-of-the-art electronics packaging techniques have been developed. This study presents a novel and cost-efficient 3D wafer level packaging technology based on co-planar Au–Si bonding structures, whose two remarkable features are (1) eliminating the height difference derived from multi-layer metal interconnection lines crossing bonding rings by building co-planar bonding structures and (2) accomplishing vertical interconnections of low-resistivity Si column structures by forming Au–Si bonding ohmic contacts. In this paper, the packaging structure is interpreted by designs, fabrications and tests, in which the efficiency verification on co-planar bonding structures and vertical interconnections is concretely addressed. The performances on co-planar bonding structures have been revealed by 3D profiles of bonding surfaces, cross-sectional SEM images (the gap-free bonding layer) and tensile tests for Au–Si bonding strength. Besides, tests on leak rates of packaged chips indicate good packaging hermeticity. In terms of vertical interconnection properties, an in situ extracting method on the specific contact resistance ( ρ _c ) is also introduced to quantitatively appraise the quality of Au–Si ohmic contacts. Therefrom, the measured resistance of a vertical interconnection (~1 Ω) could be qualified for most devices’ interconnection requirements. And further, the extracted ρ _c values of 1.83–3.48 × 10 ⁻⁸ Ω · m ² also imply forming of good ohmic contacts in Au–Si bonding. More importantly, being analogously conducted by any available eutectic bonding techniques, this 3D packaging method has inherently extensive application prospects.

To compare the effects of transcatheter arterial chemoembolization (TACE) with transcatheter arterial embolization (TAE) on liver function, hepatic damage, and hepatic fibrogenesis in a rabbit tumor model. Thirty-nine New Zealand white rabbits implanted with VX2 tumors in the left liver lobes were randomly divided into three groups: TAE, TACE, and control group. In the TAE group (n = 15), polyvinyl alcohol particles (PVAs) were used for left hepatic artery embolization. In the TACE group (n = 15), the tumors were treated with left hepatic arterial infusions of a suspension of 10-hydroxycamptothecin and lipiodol, followed by embolization with PVAs. In the control group (n = 9), the animals received sham treatment with distilled water. Serum and liver samples were collected at 6 hours, 3 days and 7 days after treatment. Liver damage was measured using a liver function test and histological analyses. Liver fibrogenesis and hepatic stellate cell (HSC) activation were evaluated using Sirius Red and anti-alpha-smooth muscle actin (α-SMA) immunohistochemical stains. TACE caused liver injury with greater increases in serum alanine aminotransferase and aspartate aminotransferase levels on day 3 (P<0.05). Histological analyses revealed increased hepatic necrosis in adjacent non-tumorous liver tissue from day 3 compared to the TAE group (Suzuki score of 2.33±1.29 versus 1.13±1.18, P = 0.001). HSC activation and proliferation were significantly increased in the TACE group compared to the control group at 3 and 7 days after treatment (0.074±0.014 vs. 0.010±0.006, and 0.088±0.023 vs. 0.017±0.009, P<0.05). Sirius Red staining demonstrated a statistically significant increase in collagen deposition in the livers in the TACE group 7 days after embolization compared to the control group (0.118±0.012 vs. 0.060±0.017, P = 0.05). The results of this animal study revealed that TACE induced prominent hepatocellular damage and hepatic fibrogenesis, which compromised liver function and may be responsible for chronic liver decompensation.