Inverted-load network for high-power Doherty amplifier

In this article, a high-power, high-efficiency inverted Doherty power amplifier (PA), having a more compact load network than that of the conventional Doherty amplifier, was designed and implemented for wide-band code-division multiple access (WCDMA) base-station applications. Its configuration and working principle are compared with the conventional Doherty amplifier. For experimental verification, we implemented an inverted Doherty amplifier, using a 190 W peak-envelope-power (PEP) laterally diffused metal-oxide-semiconductor (LDMOS) field-effect transistors (FETs). Using a four-carrier down-link WCDMA signal, we achieved a high power-added efficiency (PAE) of 32% and an average output power level as high as 46.3 dBm at a given adjacent channel leakage ratio (ACLR) level of -30 dBc. This is a 9.5% improvement in efficiency and 1 dB improvement in output power under the same ACLR conditions from those of the balanced class-AB operation using the same devices.     

Gene expression profiling in streptozotocin-induced diabetic rat liver in response to fungal polysaccharide treatment

We established the gene expression profiling in streptozotocin (STZ)-induced diabetic rat liver in response to hypoglycemic fungal polysaccharides (EPS), using oligonucleotide microarray analysis. Differentially regulated genes showing higher fold change than 2 were identified and categorized through hierarchical clustering analysis. Among the 835 genes analyzed, 244 were up-regulated, while 321 were down-regulated after diabetes induction. Interestingly, many gene expressions altered after STZ-treatment mimicked a normal rat liver by EPS therapy. Most of these genes included genes involving cell structure and motility, immunity and defense, lipid, fatty acid and steroid metabolism, protein metabolism and modification, and signal transduction. More importantly, we found a total of 36 genes that showed significant fold changes in their expression that have not previously been examined in the context of diabetes. To validate the microarray results, we further confirmed the gene expression patterns by RT-PCR using four genes of interest (carboxylesterase 2, stearoyl-coenzyme A desaturase 1, insulin-like growth factor 1, and insulin-like growth factor binding protein 2). Taken together, EPS acted as a potent regulator of gene expression for a wide variety of genes in diabetic rat liver.     

Purification and characterization of recombinant human erythropoietin from milk of transgenic pigs

BACKGROUND: Human erythropoietin (hEPO), a hydrophobic acidic glycoprotein responsible for the regulation of red blood cell production in mammals, is used for the treatment of anemia. In general, the purification of transgenic animal‐derived therapeutic proteins is not easy due to their low titer concentrations and abundant contaminant proteins. For the first time, here the purification and characterization of rhEPO from the milk of transgenic pigs are described. RESULTS: The rhEPO was purified by heparin chromatography, reverse‐phase chromatography, and gel filtration chromatography, resulting in a 16.5% yield and > 98% purity. The rhEPO purified from the milk of transgenic pigs contained less acidic isoforms and was underglycosylated in contrast to CHO‐derived rhEPO. Cell proliferation of the F‐36/EPO‐dependent cell line was proportional to the dose of transgenic pig‐derived rhEPO. CONCLUSION: Transgenic pig‐derived rhEPO with high purity was achieved after three‐step chromatography following two‐step precipitation. The transgenic pig‐derived rhEPO was demonstrated to have comparable potency with CHO‐derived rhEPO. Transgenic pig‐derived rhEPO may not be therapeutically feasible because of different glycosylation, and thus further studies are required to elucidate the effect of this aberrant glycosylation on the biological activity and stability in vivo. Copyright © 2008 Society of Chemical Industry     

Nanogap Array Fabrication Using Doubly Clamped Freestanding Silicon Nanowires and Angle Evaporations

We present a simple semiconductor process to fabricate nanogap arrays for application in molecular electronics and nano‐bio electronics using a combination of freestanding silicon nanowires and angle evaporation. The gap distance is modulated using the height of the silicon dioxide, the width of the Si nanowires, and the evaporation angle. In addition, we fabricate and apply the nanogap arrays in single‐electron transistors using DNA‐linked Au nanoparticles for the detection of DNA hybridization.     

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.     

Protective Effect of Microencapsulation Consisting of Multiple Emulsification and Heat Gelation Processes on Immunoglobulin in Yolk

ABSTRACT: Two different emulsification methods involving multiple emulsification and heat gelation were used for preparation of whey protein-based microcapsules containing immunoglobulin in yolk (IgY). The residual activity of IgY during the emulsion preparation and the effects of microencapsulation on IgY stability under harsh conditions were investigated. The residual activity of IgY in an emulsion prepared with a membrane emulsifier was higher than for an emulsion using a homogenizer. Microencapsulated IgY showed remarkable stability against both pepsin and acid. Both microencapsulated IgY and nonencapsulated IgY were relatively stable in bile and artificial intestinal juice. Microencapsulated IgY retained 74% of initial activity during heat treatment. There were no significant differences in the residual activities of microencapsulated IgY under storage temperatures of 4, 25, and 37°C.     

Development of a Meat-Like Process Flavoring from Soybean-Based Enzyme-Hydrolyzed Vegetable Protein (E-HVP)

ABSTRACT: Response surface methodology (RSM) was used to develop a meat-like process flavoring agent from enzyme-hydrolyzed vegetable protein (E-HVP). Five factors were evaluated: pH (3.6 to 8.4), temperature (51 to 99 °C), heating period (0.3 to 2.7 h), amount of ribose (0 to 1 × KHmol) and amount of cysteine (0 to 1 × 10 ³mol). Sensory analysis limited to aroma in terms of overall liking and intensity of specific aroma attributes was investigated. The aroma attributes measured included bean-like, potato-like, Brussels sprouts-like, molasses-like, chicken-like, beef-like, egg-like, roasted and apple sauce-like). Based on the fitted surfaces and consumer test data (overall liking), the optimum reaction conditions for production of a meat-like flavoring were pH 6,99 °C reaction temperature, 1.5 h heating time, 5 × 10⁻⁴ mol of ribose and 5 × 10⁻⁴ mol of cysteine.     

Nanodosimetric measurements with an avalanche confinement TEPC

This paper illustrates a tissue-equivalent proportional counter designed to have high gas gain and good energy resolution at nanometric simulated site sizes. Microdosimetric neutron and gamma spectra were measured in dimethyl ether and in propane-based tissue-equivalent gas mixture down to 35 nm. The comparison of experimental data with the results of Monte Carlo calculations shows a satisfactory agreement.     

Simple and compact, all-fibre retro-reflector for cladding-pumped fibre lasers

Proposed is an all-fibre retro-reflector realised via shaping a fibre end into a right-angled cone for a pump reflector in cladding-pumped fibre lasers. The conical-shaped fibre-optic retro-reflector allows folded, total internal reflections for pump beams that propagate in the inner cladding of a double-clad fibre. The proposed scheme was applied to a cladding-pumped ytterbium-doped fibre laser and readily achieved over 55% of reflection for the unabsorbed pump throughput, thereby generating 29% more signal output power than without the pump retro-reflector     

Evaluation of thermal contact conductance using a new experimental-numerical method in fin-tube heat exchangers

In a fin-tube heat exchanger the contact between fin collar and tube surface is obtained through mechanical expansion of tubes. Since the interfaces between the tubes and fins consist partially of metal-to-metal contact and partially of air, the features of heat transfer through the contact interfaces have not been fully investigated. The present study aims at the development of a new tool including an experiment and a numerical calculation for the estimation of the thermal contact conductance between the fin collar and tube surface, and pursues the evaluation of the factors affecting the thermal contact conductance in a fin-tube heat exchanger. Heat exchangers fabricated for the current study have been put to the test for heat balance in a vacuum chamber with water as an internal fluid. And a finite difference numerical scheme has been used for the data reduction of the experimental data to evaluate the thermal contact conductance. Fin-tube heat exchangers employed in the current research are of tube diameter of 7 mm with different tube expansion ratios, fin spacings, and fin types. The results of the present study imply that these parameters as well as hydrophilic fin coating have a significant effect on the thermal contact conductance. It has been discovered that the portion of the thermal contact resistance is not negligible compared with the total thermal resistance in a fin-tube heat exchanger, and this means that in order to reduce the thermal contact resistance thoughtful care should be taken in fabricating heat exchangers.