A 90-nm Wideband Merged CMOS LNA and Mixer Exploiting Noise Cancellation

This paper describes the design and implementation of a wideband merged LNA and mixer chip covering the frequency range from 0.1 to 3.85 GHz using 90-nm CMOS technology. Its high level of integration as well as its low power consumption makes it suitable for the rapidly growing software defined radio RF receivers. The chip performance achieves S11 below -10 dB along the entire band and a minimum single side band noise figure of 8.4 dB at IF frequency of 70 MHz. Power conversion gain is measured to be 12.1 dB while the input referred 1 dB compression point is measured to be -12.8 dBm. The chip core consumes only 9.8 mW from a 1.2 V supply with a die area, including the pads, of 0.88 mm²     

Multi-objective topology optimization of multi-component continuum structures via a Kriging-interpolated level set approach

This paper explores a framework for topology optimization of multi-component sheet metal structures, such as those often used in the automotive industry. The primary reason for having multiple components in a structure is to reduce the manufacturing cost, which can become prohibitively expensive otherwise. Having a multi-component structure necessitates re-joining, which often comes at sacrifices in the assembly cost, weight and structural performance. The problem of designing a multi-component structure is thus posed in a multi-objective framework. Approaches to solve the problem may be classified into single and two stage approaches. Two-stage approaches start by focusing solely on structural performance in order to obtain optimal monolithic (single piece) designs, and then the decomposition into multiple components is considered without changing the base topology (identical to the monolithic design). Single-stage approaches simultaneously attempt to optimize both the base topology and its decomposition. Decomposition is an inherently discrete problem, and as such, non-gradient methods are needed for single-stage and second stage of two-stage approaches. This paper adopts an implicit formulation (level-sets) of the design variables, which significantly reduces the number of design variables needed in either single or two stage approaches. The number of design variables in the formulation is independent from the meshing size, which enables application of non-gradient methods to realistic designs. Test results of a short cantilever and an L-shaped bracket studies show reasonable success of both single and two stage approaches, with each approach having different merits.     

A new systematic firefly algorithm for forecasting the durability of reinforced recycled aggregate concrete

This study presents a new systematic algorithm to optimize the durability of reinforced recycled aggregate concrete. The proposed algorithm integrates machine learning with a new version of the firefly algorithm called chaotic based firefly algorithm (CFA) to evolve a rational and efficient predictive model. The CFA optimizer is augmented with chaotic maps and Lévy flight to improve the firefly performance in forecasting the chloride penetrability of strengthened recycled aggregate concrete (RAC). A comprehensive and credible database of distinctive chloride migration coefficient results is used to establish the developed algorithm. A dataset composite of nine effective parameters, including concrete components and fundamental characteristics of recycled aggregate (RA), is used as input to predict the migration coefficient of strengthened RAC as output. k-fold cross validation algorithm is utilized to validate the hybrid algorithm. Three numerical benchmark analyses are applied to prove the superiority and applicability of the CFA algorithm in predicting chloride penetrability. Results show that the developed CFA approach significantly outperforms the firefly algorithm on almost tested functions and demonstrates powerful prediction. In addition, the proposed strategy can be an active tool to recognize the contradictions in the experimental results and can be especially beneficial for assessing the chloride resistance of RAC.     

The microbial flora of Awshari cheese with special reference to lactobacilli

Thirty seven samples of Awshari cheese and 13 of Biza were examined microbiologically. Penicillia occurred in 2 samples of cheese and yeasts in 21, 3 of which contained Saccharomyces lactis. In 8 samples studied for the constitutive microflora, lactobacilli and streptococci were the most prevalent, with L. casei being the only Lactobacillus species isolated. Penicillia and yeasts occurred in all the samples of Biza, with Saccharomyces lactis being encountered in 5 out of 6 samples examined for the type of yeasts. The microbial flora consisted primarily of lactobacilli. Out of 98 lactobacilli isolated from 10 samples 55 were identified as betabacteria: 41 were attached to L. brevis, 13 L. buchneri and 1 L. pasteurianus. The remaining 43 isolates were streptobacteria: 21 belonged to L. coryniformis, 5 L. casei ssp pseudoplantarum, 3 ssp casei and 1 ssp alactosus, 2 L. plantarum ssp plantarum and 1 ssp arabinosus, 1 L. xylosus, 5 motile streptobacteria and 4 unidentifiable.     

Production of acetoin and diacetyl by lactic acid bacteria in skimmed milk with added citrate and pyruvate

Summary Thirty-two strains of starter cultures and lactic acid bacteria belonging to the genera Streptococcus, Leuconostoc and Lactobacillus were studied for their ability to produce acetoin (A) and diacetyl (D) from citrate and pyruvate added separately to skim milk and from pyruvate added to peptone-yeast extract-glucose broth (PYG).The largest amount of A + D was produced from citrate and by the citrate fermenters Streptococcus cremoris AM₂, Str. faecalis, Leuconostoc citrovorum ATCC 8082, L. Gasei ATCC 393, L. Gasei ssp. alactosus and L. xylosus. Some strains of Str. cremoris, Str. thermophilus, some strains of L. Gasei, L. plantarum and L. coryniformis on the contrary produced more A + D from pyruvate than from citrate. Str. cremoris AM₂ should be designated as Str. diaceticremoris like Str. diacetilactis.PYG was more favourable than skim milk for production of A + D from pyruvate by Str. lactis, some strains of Str. cremoris, Str. faecalis and lactobacilli. Pyruvate as a sole source of carbon gave a poor yield of A + D compared to itself in the presence of glucose in case of most of the streptococci and all of the lactobacilli.The largest amount of diacetyl was produced by 70% of the streptococci from citrate added to skim milk, and by the great most of the lactobacilli from pyruvate in PYG medium.

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Produktion von Acetoin durch Milchsäurebakterien in mit Zitrat und Pyruvat angereicherter Magermilch

Zusammenfassung Insgesamt 32 Säureweckerkulturen der Gattungen Streptococcus, Leuconostoc und Lactobacillus wurden unter Verwendung unterschiedlicher Nährsubstrate auf die Bildung von Acetoin und Diacetyl untersucht. Es zeigte sich, daß je nach Nährbodenzusammensetzung und Bakterienstamm unterschiedliche Mengen der genannten Aromastoffe gebildet wurden.

     

Proteolysis and electrophoretic pattern of casein of some fermented milks

Proteolysis and electrophoretic pattern of casein were determined in Friesian cows' skim milk, buffaloes' skim milk and in these milks fermented spontaneously (leben rayeb) and by Streptococcus lactis subsp. diacetylactis DRC3 (nonfat buttermilk) or by zabadi starter (zabadi). The highest proteolysis, as evidenced by the amount of released leucine, occurred in zabadi and the lowest in leben rayeb. The highest amount of tyrosine was liberated in the nonfat buttermilk. Proteolysis seems not to depend on the kind of milk used. A band of a relatively high density appeared to be released from alpha s-casein by the cell-wall proteinase of the microflora of raw milk and by heating at 90 degrees C for 1 min. Cows' skim milk, raw or heated, showed the presence of 2 probable proteose-peptone components; buffaloes' skim milk 3 and 2. These components underwent slow or rapid degradation, depending on the type of fermented milk during skim milk coagulation.     

The effect of pH on bioremediation potential for the removal of direct violet textile dye by Aspergillus niger

Alkaline and acidic media have been used in the textile dye industry, depending on the fabric nature. The bioremoval of textile direct violet dye by Aspergillus niger fungal strain was studied. The effect of pH on dye bioremoval was investigated at a pH range from 2 to 11. The direct violet dye bioremoval reached maximum with 92.4%, 64.0%, 91.4%, and 62.3 % at pH values of 2, 3, 8, and 9, respectively, at 24 h of incubation. The percentages of removal rate after 72 h incubation were 98.9, 97.3, 94.0, 95.0, 97.0, and 97.3 at pH 2, 3, 6, 7, 8, and 9, respectively. The optimum pH values were 2, 3, 8, and 9 for direct dye removal. At the end of the experiments, the treatment with fungal strain could reduce COD value of synthetic dye solution by 76-91%. Pseudo first and second order kinetic models were applied to evaluate differences in the biosorption rates and uptakes of textile dye. Pre-equilibrium biosorption of direct violet dye onto fungus under different dye concentrations followed a pseudo second order kinetic model with a high degree of correlation coefficients (R² > 0.99), and the calculated values of q_e nearly matched the experimental values of textile dye during the biotreatment process.     

Mechanism of acetic acid transfer from aqueous sodium chloride solutions to some orgranic solvents

Salting out of acetic acid from aqueous solutions containing various concentrations of sodium chloride into some organic solvents has been studied at various temperatures. The solvents include cyclohexane, carbon tetrachloride, 1,2-dichloroethane, isopropyl ether, 2-pentanone and 1-heptanol. The results are consistent with a transfer mechanism involving monomer partitioning, dimerization and dimer return to the aqueous phase. Factors favoring monomer partitioning such as rise in both temperature and salt level retard dimer return, a process which is found to be significant in dimerization-enhancing solvents. The sensitivity of various solvents towards salt effect increases in the order 1-heptanol < isopropylether < 1,2-dichloroethane < 2-pentanone < cyclohexane < carbon tetrachloride which generally parallels in the reverse order the extent of stabilization of the acid by various solvent interactions.