The effect of steaming on the free amino acid contents and antioxidant activity of Panax ginseng

This study was carried out to investigate changes in the free amino acid contents and antioxidant activity of Panax ginseng induced by steaming at different temperatures. For this purpose, white ginseng (WG), red ginseng (RG, ginseng steamed at 100 °C) and ginseng steamed at 120 °C (SG) were prepared using an autoclave. Most free amino acids were decreased significantly by steam treatment, with the greatest reduction observed in SG. Total content of free amino acids, 17.9 mg/g in WG was reduced to 12.2 mg/g in RG and 2.79 mg/g in SG. As for Arg which is the most predominant amino acid in ginseng, the content, 10.4 mg/g in WG, decreased significantly to 1.38 mg/g in SG. In particular, β-N-oxalyl-L-α,β-diaminopropionic acid (β-ODAP), a well-known neurotoxin, was reduced by 92.9% in SG. In contrast, the level of Maillard reaction products (MRPs) increased with steam treatment, which indicates that the reduction of most amino acids is attributed to the extent of the Maillard reaction. Based on MRPs being useful antioxidants, we assayed the scavenging activity against free radicals produced by 2,2′-azobis-(2-amidinopropane) dihydrochloride (AAPH). The radical scavenging activity of a ginseng extract increased with steam treatment, with the most potent activity in SG. Further, MRPs-rich fraction in SG showed powerful antioxidant activity, which indicates MRPs are major contributors to antioxidant activity enhanced by steam treatment.     

Antimicrobial resistance of Escherichia coli O157 from cattle in Korea

Of 45 Escherichia coli O157 isolates from cattle feces, which were collected between May 2000 and September 2003 in Korea, 32 were resistant to at least 1 antibiotic and 28 were resistant to 4 or more antibiotics, with 32, 30 and 30 of the isolates being resistant to streptomycin, tetracycline and sulfisoxazole, respectively. Two isolates were resistant to fluoroquinolones and to 10 or more of the 22 other antimicrobial agents that were tested. Thirteen antimicrobial resistant patterns were observed. The most frequent resistance type, which was found for 11 isolates, was streptomycin-tetracycline-kanamycin-ampicillin-piperacillin-cephalothin-sulfisoxazole-ticarcillin. Polymerase chain reaction (PCR) analysis of the isolates for E. coli O157 virulence markers revealed that 25 of the resistant E. coli O157 isolates tested positive for stx2 or both stx1 and stx2 genes. These findings suggest that many of the resistant E. coli O157 isolates might cause disease in humans.     

Effect of Tungsten and Molybdenum Doping on the Semiconductor–Metallic Transition in Vanadium Dioxide Produced by Evaporative Decomposition of Solutions and Hydrogen Reduction

V_{1– x} W _x O₂ and V_{1– x} Mo _x O₂, 0 < x < 0.03, powders have been produced by the evaporative decomposition of solutions of vanadyl sulfate hydrate with tungsten dioxide dichloride or molybdenum dioxide dichloride in a hydrogen/nitrogen atmosphere. The powders consist primarily of hollow, porous, spherical shells. Differential scanning calorimetric analysis of the powders indicates that the 67°C mono-clinic-tetragonal phase transition in VO₂ shifts to lower temperatures by 23°C/(at.% tungsten) and 6.3°C/(at.% molybdenum).     

A Boronic Acid Assay for the Detection of Mucin‐1 Glycoprotein from Cancer Cells

Cell surface glycoproteins are commonly aberrant in disease and act as biomarkers that facilitate diagnostics. Mucin‐1 (MUC1) is a prominent example, exhibiting truncated glycosylation in cancer. We present herein a boronic acid microplate assay for sensitive and high‐throughput detection of such glycoproteins. The immobilization of biotin–boronic acid 1 onto streptavidin plates generated a multivalent surface for glycoprotein recruitment and detection. We first validated the binding properties of 1 in solution through titrations with alizarin dye. Next, the microplate assay was explored through horseradish peroxidase (HRP) analysis as a proof‐of‐concept glycoprotein with chemiluminescence detection. Finally, this platform was applied for the detection of MUC1 directly from MCF‐7 human breast cancer cell lysates by using an HRP‐tagged antibody that targets the cancerous form of this glycoprotein. Sensitive, dose‐dependent detection of MUC1 was observed, showcasing the efficacy of this platform for detecting disease‐associated glycoproteins.     

Low-bandgap copolymers consisting of 2,1,3-benzoselenadiazole and carbazole derivatives with thiophene or selenophene π-bridges

Two donor–acceptor-type alternating copolymers consisting of 2,1,3-benzoselenadiazole and carbazole derivatives with thiophene or selenophene π-bridges were synthesized by Suzuki cross-coupling polymerization, and their optical, electrochemical, and photovoltaic properties were compared. The selenophene π-bridged copolymer (PCz-DSeBSe) exhibited a smaller band-gap (1.82 eV) than the thiophene-bridged polymer (PCz-DTBSe; 1.89 eV). PCz-DSeBSe also showed a deeper highest occupied molecular orbital energy level (−5.36 eV) than PCz-DTBSe (−5.20 eV). Moreover, the PCz-DSeBSe thin film showed higher crystallinity and hole mobility than the PCz-DTBSe thin film. Organic photovoltaic devices were fabricated using the polymers as the donors and [6,6]-phenyl-C₇₁-butyric acid methyl ester (PC₇₁BM) as the acceptor. The device using PCz-DSeBSe showed a higher open circuit voltage (V_oc), short circuit current density (J_sc), and power conversion efficiency (PCE) than that using PCz-DTBSe. The fabricated indium tin oxide/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/PCz-DSeBSe:PC₇₁BM/LiF/Al device showed the maximum PCE of 2.88% with a J_sc of 7.87 mA/cm², an V_oc of 0.80 V, and a fill factor of 0.50 under AM 1.5G irradiation (100 mW/cm²).     

Multigroup pin power reconstruction with two-dimensional source expansion and corner flux discontinuity

A pin power reconstruction method that is readily applicable to multigroup problems with superior accuracy is presented for applications involving rectangular fuel assemblies. It employs a two-dimensional (2D), fourth order Legendre expansion of the source distribution that naturally leads to a group-decoupled, 2D semi-analytic solution of the neutron diffusion equation. The four surface average currents and four corner fluxes are used as the boundary conditions to uniquely specify the homogenous solution. The corner fluxes and source expansion coefficients are iteratively determined using the condition of corner point balance and the orthogonal property of the Lengedre functions. Corner discontinuity is incorporated in the calculation of the corner fluxes which turns out to be very effective in the cases of enrichment zoning. The accuracy of the proposed method is assessed by performing the two-step core calculations for the L336C5, C5G7MOX, and MOX core transient benchmark problems and then by comparing with the direct whole-core transport solutions. The results indicate that the proposed method is as accurate as the fully analytic method and works well irrespective the number of groups. However, it is also noted that somewhat larger errors are inevitable at the peripheral assemblies near the reflector in which the error associated with a prioi generation of the homogenized cross-sections and form functions is not trivial.     

Treatment of taste and odor material by oxidation and adsorption.

Massive blooms of blue-green algae in reservoirs produce the musty-earthy taste and odor, which are caused by compounds such as 2-MIB and geosmin. 2-MIB and geosmin are rarely removed by conventional water treatment. Their presence in the drinking water, even at low levels (ng/L), can be detected and it creates consumer complaints. So those concentrations have to be controlled as low as possible in the drinking water. The removals by oxidation (O3, Cl2, ClO2) and adsorption (PAC, filter/adsorber) were studied at laboratory and pilot plant (50 m3/d) to select suitable 2-MIB and geosmin treatment processes. The following conclusions were derived from the study. Both of the threshold odor levels for 2-MIB and geosmin appeared to be 30 ng/L as a consequence of a lab test. For any given PAC dosage in a jar-test, removal efficiencies of 2-MIB and geosmin were increased in proportion to PAC dosage and were independent of their initial concentration in raw water for the tested PAC dosages. In comparison of geosmin with 2-MIB, the adsorption efficiency of geosmin by PAC was superior to that of 2-MIB. The required PAC dosages to control below the threshold odor level were 30 mg/L for geosmin and 50 mg/L for 2-MIB at 100 ng/L of initial concentration. Removal efficiencies of odor materials by Cl2, ClO2, and O3 were very weak under the limited dosage (1.5 mg/L), however increased ozone dosage (3.8 mg O3/L) showed high removal efficiency (84.8% for 2-MIB) at contact time 6.4 minutes. According to the initial concentrations of 2-MIB and geosmin, their removal efficiencies by filter/adsorber differed from 25.7% to 88.4%. For all those, however, remaining concentrations of target materials in finished waters were maintained below 30 ng/L. The longer run-time given for the filter/adsorber, the higher the effluent concentration generated. So it is necessary that the run-time of the filter/adsorber be decreased, when 2-MIB or geosmin occurs in raw water.     

Characteristics of GdGaO grown by MBE

Ga₂O₃/GdGaO dielectric stacks have been grown on GaAs for MOSFETs. This paper highlights variations in the characteristics of GdGaO as the Gd flux, Ga₂O flux and substrate temperature are changed. The growth rate, composition, crystallinity are discussed and the sheet resistance of final MOSFET structures are presented. The Gd compositional variation with depth is examined using Rutherford back scattering (RBS) and electron energy loss spectroscopy (EELS).     

UNSTRUCTURED FINITE-VOLUME METHOD FOR RADIATIVE HEAT TRANSFER IN A COMPLEX TWO-DIMENSIONAL GEOMETRY WITH OBSTACLES

The radiative heat transfer in a complex two-dimensional enclosure with obstacles with participating medium is very important in practical engineering applications. In order to deal with this problem, in this study the finite-volume method (FVM) for radiation has been derived using the unstructured grid system. A general discretization equation was formulated by introducing the directional weight and the step scheme for spatial differencing. For its comparison and validation, two test cases, an equilateral triangular enclosure and a square enclosure with baffle, were chosen. Then, more complex and practical cases, such as a semicircular enclosure with cylinder hole, a square enclosure with finned internal cylinder, and a furnace with embedded cooling pipes, were investigated. All the results obtained by the unstructured FVM agreed very well with the exact solutions as well as the results obtained by the zone method. Furthermore, the wiggling behavior occurring in the blocked-off FVM was not produced by the unstructured FVM. Three types of manipulation of control angle overlap were also examined here. It was found that the solutions depended on the type of manipulation of control angle overlap, especially when the number of control angles was small. Usually, both the pixelation method and exact treatment introduced here yielded better solutions than the bold approximation.