Enhancement of the cytotoxicities and antioxidative activities of white ginseng extract by hydrolysis under mild acidic conditions

White ginseng extract (WGE) was hydrolyzed with organic acids to increase the yield of ginsenoside Rg₃ which has high bio-functional activities. The condition of hydrolysis by citric acid was studied to maximize a production of ginsenoside Rg₃. The total content of ginsenoside Rg₃ in WGE treated with 10% citric acid at 110°C for 1 h was 10-folds greater than that of commercial extract. The antitumor and antioxidant activities of WGE and the acid-hydrolysates were evaluated via an MTT assay and the DPPH method, respectively. At 1.0 mg/mL, hydrolysates inhibited the proliferation of AGS and Hep-2 cells by more than 90%, but did not inhibit their growth. It suggests that citric acid hydrolysis enhances the content of Rg₃. In addition, the acid hydrolysates evidenced a free radical scavenging activity of 80% at a concentration of 4.0 mg/mL, while WGE exhibited only a 49% free radical scavenging activity at the same concentration.     

In vivo functional effects of Weissella confusa VP30 exopolysaccharides on loperamide-induced constipation in rats

Food Science and Biotechnology - In this work, the in vivo functionalities of milk fermented with Weissella confusa VP30 (VP30-EPS) and purified exopolysaccharide (pEPS) from the milk fermented...     

Tool design in a multi-stage drawing and ironing process of a rectangular cup with a large aspect ratio using finite element analysis

Tool design is carried out for a multi-stage deep drawing and ironing process of a rectangular cup with the large aspect ratio using the result of the finite element analysis. The analysis incorporates three-dimensional continuum elements for an elasto-plastic finite element method with the explicit time integration scheme using LS-DYNA3D. The analysis simulates the five-stage deep drawing and ironing process with the thickness control of the cup wall. Simulation is performed in order to investigate the failure by tearing during the forming process at the initial state of tool design. The analysis reveals that the difference of the drawing ratio within the cross section induces non-uniform metal flow which causes severe local extension. The irregular contact condition between the blank and the die also induces non-uniform metal flow which causes local wrinkling. This paper identifies such unfavorable mechanism in the rectangular cup drawing with ironing and proposes a new tool design with the guideline for modification in the design of the process and the sequential tool shape. The finite element analysis result with the improved tool design confirms that the proposed design not only reduces the possibility of failure but also improves the quality of a deep-drawn product. The numerical result shows fair coincidence with the experimental result.     

ZnBO-doped (Ba, Sr)TiO3 ceramics for the low-temperature sintering process

ZnBO-doped (Ba, Sr)TiO₃ ceramics were investigated for low-temperature co-fired ceramics (LTCCs) applications. Until now, B₂O₃ and Li₂CO₃ dopants have been commonly employed as the low-temperature sintering aids. In this paper, we suggest ZnBO as an alternative dopant to the B₂O₃ and Li₂CO₃. To reduce the sintering temperature of (Ba, Sr)TiO₃, we have added 1–5 wt.% of ZnBO to (Ba, Sr)TiO₃. ZnBO-doped (Ba, Sr)TiO₃ ceramics were respectively sintered from 750 to 1350 °C by 50 °C to confirm the sintering temperature with different dopant contents. By adding 5 wt.% of ZnBO to the (Ba, Sr)TiO₃ ceramics, the sintering temperature of (Ba, Sr)TiO₃ ceramics can be reduced to 1100 °C. From the XRD analysis, ZnBO-doped (Ba, Sr)TiO₃ has no pyro phase. By adding ZnBO dopants to (Ba, Sr)TiO₃ ceramics, both of relative dielectric permittivity and loss tangent were decreased. From the frequency dispersion of dielectric properties, the relative dielectric permittivity and loss tangent of 5 wt.% ZnBO-doped (Ba, Sr)TiO₃ were 1180 and 3.3 × 10⁻³, while those of BST were 1585 and 4.8 × 10⁻³, respectively.     

A case of end-stage renal disease initially manifested with visual loss caused by uremic optic neuropathy

Uremic optic neuropathy (UON) is extremely rare, although sporadic cases have been reported. UON is sometimes regarded as a manifestation of uremic neuropathy. Here, we report a case of end-stage renal disease presenting as UON. A 22-year-old male was transferred to our nephrology department due to azotemia. Sudden deterioration of his vision occurred 3 days before his transfer. The patient's blood pressure was 150/90 mmHg, and he had no symptoms or signs of uremia, except for the visual disturbance. Blood tests showed an elevated serum creatinine of 6.0 mg/dL and serum BUN of 53.6 mg/dL. Both kidneys were decreased in size on ultrasound. His best-corrected vision was 20/62.5 in both the eyes. Ophthalmoscopy revealed hyperemia, swelling of both optic nerve heads, and blurred margins of both optic disks. These findings are compatible with UON. The patient's visual acuity and visual field improved following hemodialysis and corticosteroid treatment. The swelling of the patient's optic disks was also resolved. The patient is currently undergoing hemodialysis with the goal of vision restoration. Uremic optic neuropathy should be considered when patients with advanced chronic kidney disease complain of deterioration of their vision.     

Li-doped (Ba,Sr)TiO3 thick film interdigital capacitors for microwave applications

Microwave properties of Li-doped (Ba,Sr)TiO₃ thick film interdigital capacitors have been investigated. According to the reported papers, BaSrTiO₃ materials, paraelectric state at the room temperature, have high dielectric permittivity (>500 @ 1 MHz) and low loss tangent (<0.01 @ 1 MHz) in epitaxial thin film form; however, the sintering temperature of BaSrTiO₃ is over 1350 °C. In order to reduce the sintering temperature, Li (3 wt%) was added to the BaSrTiO₃ materials, and 10 μm thick Li-doped (Ba,Sr)TiO₃ films were screen printed on the alumina (Al₂O₃) substrate and sintered at 900 °C. Interdigital capacitor patterns with five fingers of 200 μm gap and 250 μm length were also designed and fabricated by employing the screen printing method with Ag electrode. The structural feature was analyzed with X-ray diffraction method. Frequency and temperature-dependent dielectric properties were characterized from 1 kHz to 1 MHz and 303-403 K, respectively. Also, current-voltage characteristics were investigated with an elevated temperature. Microwave transmission and reflectance properties of thick film interdigital capacitors will be discussed, and frequency dispersion of dielectric properties will be presented. Specially, designed Au/Li-doped (Ba,Sr)TiO₃/Ag-Pd/Al₂O₃ vertical structure was prepared to measure the tunability. In this sandwich type structure, Li-doped (Ba,Sr)TiO₃ films showed tenability of 7.15% at a bias electric field of 20 kV/cm.     

Evaluation of elastic properties and temperature effects in Si thin films using an electrostatic microresonator

Laterally driven microresonators were used to estimate the temperature-dependent elastic modulus of single-crystalline Si for microelectromechanical systems (MEMS). The resonators were fabricated through surface micromachining from silicon-on-glass wafers. They were moved laterally by alternating electrostatic force at a series of frequencies, and then a resonance frequency was determined, under temperature cycling in the range of 25/spl deg/C to 600/spl deg/C, by detecting the maximum displacement. The elastic modulus was obtained in the temperature range by Rayleigh's energy method from the detected resonance frequency. At this time, the temperature dependency of elastic modulus was affected by surface oxidation as well as its intrinsic variation: a temperature cycle permanently reduces the resonance frequency. The effect of Si oxidation was analyzed for thermal cycling by applying a simple composite model to the measured frequency data; here the oxide thickness was estimated from the difference in the resonance frequency before and after the temperature cycle, and was confirmed by field-emission scanning electron microscopy. Finally, the temperature coefficient of the elastic modulus of Si in the <110> direction was determined as -64/spl times/10/sup -6/[/spl deg/C/sup -1/]. This value was quite comparable to those reported in previous literatures, and much more so if the specimen temperature is calibrated more exactly.     

Core-shell heterostructured phase change nanowire multistate memory

Phase-change memory, which switches reversibly between crystalline and amorphous phases, is promising for next generation data-storage devices. In this work, we present a novel, nonbinary data-storage device using core-shell nanowires to significantly enhance memory capacity by combining two phase-change materials with different electronic and thermal properties to engineer different onsets of amorphous-crystalline transitions. Electric-field induced sequential amorphous-crystalline transition in core-shell nanowires displays three distinct electronic states with high, low, and intermediate resistances, assigned as data "0", "1", and "2".     

The microwave properties of Li doped 0.7(Ba,Sr)TiO3-0.3MgO thick film interdigital capacitors on the alumina substrates

The crystalline and electrical properties of Li doped 0.7(Ba,Sr)TiO₃-0.3MgO thick film interdigital capacitors have been investigated. Screen printing method was employed to fabricate Li doped 0.7(Ba,Sr)TiO₃-0.3MgO thick films on the alumina substrates. (Ba,Sr)TiO₃ materials have high dielectric permittivity (>500 @ 1 MHz) and low loss tangent (0.01 @ 1 MHz) in the epitaxial thin film form. To improve dielectric properties and reduce sintering temperature, MgO and Li were added, respectively. 10 μm thick films were screen printed on the alumina substrates and then interdigital capacitors with seven fingers of 200 μm finger gap were patterned with Ag electrode. Current-voltage characteristics were analyzed with elevated temperature range. Up to 50 °C, the thick films showed positive temperature coefficient of resistivity (dρ/dT) of 6.11 × 10⁸ Ω cm/°C, then film showed negative temperature coefficient of resistivity (dρ/dT) of −1.74 × 10⁸ Ω cm/°C. From the microwave measurement, the relative dielectric permittivity of Li doped 0.7(Ba,Sr)TiO₃-0.3MgO thick films interdigital capacitors were between 313 at 1 GHz and 265 at 7 GHz.     

Direct Imaging of Dopant and Impurity Distributions in 2D MoS2

Molybdenum disulfide (MoS₂) nanosheet is a two-dimensional (2D) material with high electron mobility and with high potential for applications in catalysis and electronics. MoS₂ nanosheets are synthesized using a one-pot wet-chemical synthesis route with and without Re doping. Atom probe tomography reveals that 3.8 at% Re is homogeneously distributed within the Re-doped sheets. Other impurities are also found integrated within the material: light elements including C, N, O, and Na, locally enriched up to 0.1 at%, as well as heavy elements such as V and W. Analysis of the nondoped sample reveals that the W and V likely originate from the Mo precursor. It is shown how wet-chemical synthesis results in an uncontrolled integration of species from the solution that can affect the material's activity. The results of this work are expected to contribute to an improved understanding of the relationships linking composition to properties of 2D transition-metal dichalcogenide materials.