106 research outputs found
PSO-based Parameter Estimation of Nonlinear Kinetic Models for ÎČ-Mannanase Fermentation
Particle swarm optimization (PSO), as a novel evolutionary algorithm involved in social interaction for global space search, was firstly used in kinetic parameter estimation. Based on three developed nonlinear kinetic equations for bacterial cell growth, total sugar utilization and ÎČ-mannanase production by Bacillus licheniformis under the support of a batch fermentation process, various PSO algorithms as well as gene algorithms (GA) were developed to estimate kinetic parameters. The performance comparison among these algorithms indicates the improved PSO (Trelea 1) is most suitable for kinetic parameter estimation of ÎČ-mannanase fermentation. In order to find the physical-chemical-meanings of kinetic parameters from many optimized results, multiobjective optimization with a normalized weight method was adopted. The 9 desired parameters in equations were obtained by the Trelea 1 type PSO with two batches fermentation data, and the results predicted by the models were also in good agreement with the experimental observations
Crystal Structure, Infrared Spectra, and Microwave Dielectric Properties of Temperature-Stable Zircon-Type (Y,Bi)VO<inf>4</inf> Solid-Solution Ceramics
A series of (Bi 1-x Y x )VO 4 (0.4 †x †1.0) ceramics were synthesized using the traditional solid-state reaction method. In the composition range of 0.4 †x †1.0, a zircon-type solid solution was formed between 900 and 1550 °C. Combined with our previous work (scheelite monoclinic and zircon-type phases coexist in the range of x < 0.40), a pseudobinary phase diagram of BiVO 4 -YVO 4 is presented. As x decreased from 1.0 to 0.40, the microwave permittivity (ϔ r ) of (Bi 1-x Y x )VO 4 ceramics increased linearly from 11.03 to 30.9, coincident with an increase in the temperature coefficient of resonant frequency (TCF) from -61.3 to +103 ppm/°C. Excellent microwave dielectric properties were obtained for (Bi 0.3 Y 0.7 )VO 4 sintered at 1025 °C and (Bi 0.2 Y 0.8 )VO 4 sintered at 1075 °C with ϔ r ⌠19.35, microwave quality factor (Qf) ⌠25 760 GHz, and TCF ⌠+17.8 ppm/°C and ϔ r ⌠16.3, Qf ⌠31 100 GHz, and TCF ⌠-11.9 ppm/°C, respectively. Raman spectra, Shannon's additive rule, a classical oscillator model, and far-infrared spectra were employed to study the structure-property relations in detail. All evidence supported the premise that Bi-based vibrations dominate the dielectric permittivity in the microwave region
High Quality Factor, Ultralow Sintering Temperature Li6B4O9 Microwave Dielectric Ceramics with Ultralow Density for Antenna Substrates
Dense Li6B4O9microwave dielectric ceramics were synthesized at low temperature via solid-state reaction using Li2CO3and LiBO2. Optimum permittivity ⌠5.95, quality factor ⌠41 800 GHz and temperature coefficient of resonant frequency ⌠- 72 ppm/°C were obtained in ceramics sintered at 640 °C with a ultrasmall bulk density âŒ2.003 g/cm3(âŒ95% relative density, the smallest among all the reported microwave dielectric ceramics). Li6B4O9ceramics were shown to be chemically compatible with silver electrodes but reacted with aluminum forming Li3AlB2O6and Li2AlBO4secondary phases. A prototype patch antenna was fabricated by tape casting and screen printing. The antenna resonated at 4.255 GHz with a bandwidth âŒ279 MHz at -10 dB transmission loss (S11) in agreement with simulated results. The Li6B4O9microwave dielectric ceramic possesses similar microwave dielectric properties to the commercial materials but much lower density and could be a good candidate for both antenna substrate and low-temperature cofired ceramics technology
PSO-based Parameter Estimation of Nonlinear Kinetic Models for ÎČ-Mannanase Fermentation
Particle swarm optimization (PSO), as a novel evolutionary algorithm involved in social interaction for global space search, was firstly used in kinetic parameter estimation. Based on three developed nonlinear kinetic equations for bacterial cell growth, total sugar utilization and ÎČ-mannanase production by Bacillus licheniformis under the support of a batch fermentation process, various PSO algorithms as well as gene algorithms (GA) were developed to estimate kinetic parameters. The performance comparison among these algorithms indicates the improved PSO (Trelea 1) is most suitable for kinetic parameter estimation of ÎČ-mannanase fermentation. In order to find the physical-chemical-meanings of kinetic parameters from many optimized results, multiobjective optimization with a normalized weight method was adopted. The 9 desired parameters in equations were obtained by the Trelea 1 type PSO with two batches fermentation data, and the results predicted by the models were also in good agreement with the experimental observations
Structureâproperty relationships of low sintering temperature scheelite-structured (1 â x)BiVO 4 âxLaNbO 4 microwave dielectric ceramics
A series of (1 â x)BiVO4âxLaNbO4 (0.0 †x †1.0) ceramics were prepared via a solid state reaction method. A scheelite-structured solid solution was formed for x †0.5 but for x > 0.5, tetragonal scheelite, monoclinic LaNbO4-type and La1/3NbO3 phases co-existed. As x increased from 0 to 0.1, the room temperature crystal structure gradually changed from monoclinic to tetragonal scheelite, associated with a decrease in the ferroelastic phase transition temperature from 255 °C (BiVO4) to room temperature or even below. High sintering temperatures were also found to accelerate this phase transition for compositions with x †0.08. Temperature independent high quality factor Qf >10 000 GHz in a wide temperature range 25â140 °C and high microwave permittivity Δr âŒ76.3 ± 0.5 was obtained for the x = 0.06 ceramic sintered at 800 °C. However, small changes in composition resulted in a change in the sign and magnitude of the temperature coefficient of resonant frequency (TCF) due to the proximity of the ferroelastic transition to room temperature. If TCF can be controlled and tuned through zero, then (1 â x)BiVO4âxLaNbO4 (0.0 †x †1.0) is a strong candidate for microwave device applications
Crystal structure, impedance and broadband dielectric spectra of ordered scheelite-structured Bi(Sc1/3Mo2/3)O4 ceramic
Bi(Sc 1/3 Mo 2/3 )O 4 ceramics were prepared via solid state reaction method. It crystallized with an ordered scheelite-related structure (a = 16.9821(9) Ă
, b = 11.6097(3) Ă
, c = 5.3099(3) Ă
and ÎČ = 104.649(2)°) with a space group C12/C1, in which Bi 3+ , Sc 3+ and Mo 6+ are -8, -6 and -4 coordinated, respectively. Bi(Sc 1/3 Mo 2/3 )O 4 ceramics were densifiedat 915 °C, giving a permittivity (Δ r ) 24.4, quality factor (Qf, Q = 1/dielectric loss, f = resonant frequency) ~48, 100 GHz and temperature coefficient of resonant frequency (TCF) -68 ppm/°C. Impedance spectroscopy revealed that there was only a bulk response for conductivity with activation energy (E a ) ~0.97 eV, suggesting the compound is electrically and chemically homogeneous. Wide band dielectric spectra were employed to study the dielectric response of Bi(Sc 1/3 Mo 2/3 )O 4 from 20 Hz to 30 THz. Δ r was stable from 20 Hz to the GHz region, in which only ionic and electron displacive polarization contributed to the Δ r
Measurement of tamsulosin in human serum by liquid chromatography-tandem mass spectrometry
AbstractA simple, sensitive and robust method to extract tamsulosin from human serum, and quantify by liquid chromatographyâtandem mass spectrometry (LCâMS/MS) was developed and validated and is applicable as a measure of compliance in clinical research. Tamsulosin was extracted from human serum (100ÎŒL) via liquidâliquid extraction with methyl tert-butyl ether (2mL) following dilution with 0.1M ammonium hydroxide (100ÎŒL), achieving 99.9% analyte recovery. Internal standard, d9-finasteride, was synthesised in-house. Analyte and internal standard were separated on an AscentisÂź Express C18 (100mmĂ3mm, 2.7ÎŒm) column using a gradient elution with mobile phases methanol and 2mM aqueous ammonium acetate (5:95, v/v). Total run-time was 6min. Tamsulosin was quantified using a triple quadrupole mass spectrometer operated in multi-reaction-monitoring (MRM) mode using positive electrospray ionisation. Mass transitions monitored for quantitation were: tamsulosin m/z 409â228 and d9-finasteride m/z 382â318, with the structural formulae of ions confirmed by Fourier transform ion cyclotron resonance mass spectrometry (within 10ppm). The limit of quantitation was 0.2ng/mL, and the method was validated in the linear range 0.2â50ng/mL with acceptable inter- and intra-assay precision and accuracy and stability suitable for routine laboratory practice. The method was successfully applied to samples taken from research volunteers in a clinical study of benign prostatic hyperplasia
Multi-response analysis in the material characterisation of electrospun poly (lactic acid)/halloysite nanotube composite fibres based on Taguchi design of experiments: fibre diameter, non-intercalation and nucleation effects
Poly (lactic acid) (PLA)/halloysite nanotube (HNT) composite fibres were prepared by using a simple and versatile electrospinning technique. The systematic approach via Taguchi design of experiments (DoE) was implemented to investigate factorial effects of applied voltage, feed rate of solution, collector distance and HNT concentration on the fibre diameter, HNT non-intercalation and nucleation effects. The HNT intercalation level, composite fibre morphology, their associated fibre diameter and thermal properties were evaluated by means of X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), imaging analysis and differential scanning calorimetry (DSC), respectively. HNT non-intercalation phenomenon appears to be manifested as reflected by the minimal shift of XRD peaks for all electrospun PLA/HNT composite fibres. The smaller-fibre-diameter characteristic was found to be sequentially associated with the feed rate of solution, collector distance and applied voltage. The glass transition temperature (T g) and melting temperature (T m) are not highly affected by varying the material and electrospinning parameters. However, as the indicator of the nucleation effect, the crystallisation temperature (T c) of PLA/HNT composite fibres is predominantly impacted by HNT concentration and applied voltage. It is evident that HNTâs nucleating agent role is confirmed when embedded with HNTs to accelerate the cold crystallisation of composite fibres. Taguchi DoE method has been found to be an effective approach to statistically optimise critical parameters used in electrospinning in order to effectively tailor the resulting physical features and thermal properties of PLA/HNT composite fibres
Galaxy Clusters Associated with Short GRBs. II. Predictions for the Rate of Short GRBs in Field and Cluster Early-Type Galaxies
We determine the relative rates of short GRBs in cluster and field early-type
galaxies as a function of the age probability distribution of their
progenitors, P(\tau) \propto \tau^n. This analysis takes advantage of the
difference in the growth of stellar mass in clusters and in the field, which
arises from the combined effects of the galaxy stellar mass function, the
early-type fraction, and the dependence of star formation history on mass and
environment. This approach complements the use of the early- to late-type host
galaxy ratio, with the added benefit that the star formation histories of
early-type galaxies are simpler than those of late-type galaxies, and any
systematic differences between progenitors in early- and late-type galaxies are
removed. We find that the ratio varies from R(cluster)/R(field) ~ 0.5 for n =
-2 to ~ 3 for n = 2. Current observations indicate a ratio of about 2,
corresponding to n ~ 0 - 1. This is similar to the value inferred from the
ratio of short GRBs in early- and late-type hosts, but it differs from the
value of n ~ -1 for NS binaries in the Milky Way. We stress that this general
approach can be easily modified with improved knowledge of the effects of
environment and mass on the build-up of stellar mass, as well as the effect of
globular clusters on the short GRB rate. It can also be used to assess the age
distribution of Type Ia supernova progenitors.Comment: ApJ accepted versio
- âŠ