Sequential Simplex Research Articles

Quantitative Electron Probe Microanalysis of Bi-Sr-Ca-Cu-O High Tc Superconductors Using Energy- and Wavelength-Dispersive Spectrometry

Abstract: Multiple linear least squares (MLLSQ) and sequential simplex spectral processing procedures were used in an electron probe energy-dispersive (EDS) analysis of a 2223 Bi-Sr-Ca-Cu-O (BSCCO) high Tc superconductor specimen. This phase is normally difficult to quantify by EDS at voltages below 25 kV because of the severe overlap of the BiM lines with the M lines from a small amount of Pb that is added to the phase for stability. Quantitative results from the MLLSQ spectral processing and ZAF matrix correction procedures agreed well with wavelength-dispersive analysis (WDS) of the same specimen.

Simplex optimization of reaction variables in the production of cobalt(III) acetate in a bipolar packed-bed reactor

Cobalt(III) acetate production in a bipolar-packed bed reactor was investigated in terms of conversion ratio of Co(II) acetate, current yield and energy consumption. An experimental optimization was performed on the conversion ratio by the use of a sequential simplex method; cell voltage, concentrations of Co(II) acetate and sodium acetate, water content of the solution, temperature and the Faraday number of charge per mole of Co(II) acetate were chosen as reaction variables. The maximum conversion ratio in 36 electrolyses was 71.6% which could not be further improved by changing the levels of the selected variables. A record of the other performance parameters showed that the conditions for the highest conversion ratio were also suitable for satisfactory current and energy yields.

Fertilization in vitro of mouse ova from inbred and outbred strains: complete preimplantation embryo development in glucose-supplemented KSOM.

A new medium derived from the use of sequential simplex optimization methods (SOM) that overcomes the block to development beyond two cells in vitro in embryos of the CF1-cultured strain of mouse has recently been described. Contrary to previous reports, glucose was shown to have no significant inhibiting effect on embryo development to the blastocyst stage in SOM. A modification of SOM, designated KSOM, with an increased concentration of Na+ (95 mM) and K+ (2.5 mM), which has been described elsewhere, also supports growth beyond the two-cell block. KSOM produces a higher rate of compaction, a larger yield of blastocysts, and an increased rate of cell division of the trophoblast cells. We have reexamined the glucose effect by varying the concentration of glucose (either 0.2 mM or 5.56 mM) in KSOM and determined the ability of these media to support preimplantation development of CF1 female x B6D2F1 male zygotes through the blastocyst stage. Glucose is shown to have no significant inhibiting effect on development to the blastocyst stage. The yield of blastocysts is typically 85%-90%. A modification of KSOM derived from this study, designated modified KSOM, with an increased concentration of glucose (5.56 mM) and supplemented with 4 mg ml-1 BSA is now shown to support high rates of fertilization in vitro of CF1 ova with hybrid B6D2F1/CrlBR sperm and subsequent development of zygotes beyond the two-cell stage to blastocysts in high yield.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential Growth of the Mouse Preimplantation Embryo in Chemically Defined Media1

We have recently reported the use of sequential simplex optimization methods to design a medium (SOM) that overcomes the block to development beyond two cells which occurs in vitro in embryos from an outbred strain of mouse. We have examined this medium and several others for their ability to foster development of CF1 female x B6D2F1 male mouse embryos through the blastocyst stage. A modification of medium SOM, designated KSOM, with an increased concentration of K+ (2.5 mM), also supports growth beyond the two-cell block; compared to other media tested it produces a higher rate of compaction (100%), provides a larger yield of blastocysts (88%), and stimulates an increased rate of cell division of the trophoblast cells. The total cell number of KSOM-cultured blastocysts (44 +/- 12; n = 30) indicates that 5-6 cell divisions are possible when embryos are cultured for 96 h from pronuclear zygotes. This is a significant improvement in performance over that of other defined media for the culture of zygotes to blastocysts.

Development of an expert system for selection of experimental designs

An expert system has been developed to assist chemists in the selection of experimental designs for research projects. The system (named DXPERT) ranks thirteen types of experimental designs according to their suitability for projects presented by users in an interactive session. Design categories included are factorial, response surface, sequential simplex optimization, simplex mixture, and statistical testing. A desirability index is assigned to each design alternative according to project characteristics (attributes). Characteristics are interpreted based on expert knowledge built into the system. DXPERT uses mathematical concepts to mimic features of human intuition and decision making. Expert knowledge is represented by relevance factors (a number between minus one and plus one) in a multiple-alternative multiple-attribute table. Relevance factors are interpreted as fuzzy values that represent the degree to which a design belongs to the set of suitable designs. The formula for calculating design desirabilities is based on fuzzy mathematics. For efficiency purposes, the order of the questions presented to the user is driven by a maximum potential information gain algorithm. Design desirability indexes were found to be useful to researchers for the elimination of unsuitable designs and concentration of further efforts in the most applicable designs. A validation test was conducted with the participation of four other experts in the field.

Preconcentration of volatile components of foods: optimization of the steam distillation-solvent extraction at normal pressure

Optimization of the experimental conditions affecting the simultaneous steam distillation-solvent extraction of volatile components of foods was carried out by using the modified sequential simplex method. For this purpose, a new micro steam distillation-extraction device was constructed. The apparatus includes an enlarged surface condenser which contributes to preventing eventual losses of high-volatility components. Determination in the μg/l range of compounds having different polarities and volatilities are accomplished with high recoveries. The construction of the apparatus is such that the use of extraction solvents having densities either higher or lower than that of the solvent sample is feasible with only one configuration.

Discovery and Optimization of a PSI Electron‐Accepting 1,2,4‐Benzotriazine Herbicide

AbstractA random source PSI electron‐accepting herbicide lead, ethyl 1,2,4‐benzotriazine‐3‐acetate 1, was optimized using molecular probing, bioisosteric replacement, Free‐Wilson analysis, Sequential Simplex Optimization, and ultimately linear regression analysis. Some variables in the initial regression equations were found to be cross correlated, representing the same factors as revealed by factor analysis. The technique of prefiltering potential variables for linear regression analysis utilizing factor analysis is exemplified. For the set of 1 analogs, eleven independent factors were identified which were then submitted to linear regression analysis. The resulting equations are statistically more secure, all terms being independent. These equations are discussed in the context of known SAR for herbicidal PSI electron acceptors, especially the bipyridiniums.

Sequential simplex optimization in a constrained simplex mixture space in liquid chromatography

The sequential simplex method is used in a constrained simplex mixture space to optimize the liquid chromatographic separation of five neutral organic solutes: uracil, phenol, acetophonenone, methylbenzoate, and toluene. The mobile phase composition is varied while column temperature, mobile phase flow-rate, and sample concentration are held constant. The chromatographic response function and the total analysis time are used in an overall desirability function to direct the progress of the sequential simplex optimization.

Optimisation of a rapid bioassay for nisin utilising potassium efflux from sensitivePediococcus sp. cells

Addition of nisin to a K+-loaded, metabolising suspension ofPediococcus sp resulted in K+ efflux into the medium. The total K+ efflux was proportional to the logarithm of the nisin activity with a MEC of 0.7 IUml−1 and resulted in total loss of cellular K+ at 4–5 IUml nisin. Conditions were optimised for the use of K+ efflux measurements as a rapid nisin bioassay using a combination of factorial and sequential simplex procedures. A nisin assay based on K+ efflux measurements was used to follow the course of a nisin-producing fermentation.

Phonon mode study of near-lattice-matched InxGa1−xAs using micro-Raman spectroscopy

We identify the four allowable phonon modes in InxGa1−xAs on InP:InAs-like transverse optical (TO) (225±2 cm−1), InAs-like longitudinal optical (LO) (233±1 cm−1), GaAs-like TO (255±2 cm−1), and GaAs-like LO (269±1 cm−1), using the selectivity of first-order Raman scattering off the (100) normal surface and the (011) cleaved plane and detailed line-shape analysis employing a sequential simplex optimization procedure. Raman scattering off the (011) cleaved plane was achieved for the first time in thin-film InGaAs using microprobing capabilities (∼1 μm). We also identify another phonon mode R* at 244 cm−1 which is attributed to an alloy disorder mode in these films. For the five identified phonon modes, a linear relationship between the Raman frequencies and composition determined from x-ray diffraction was determined for near-lattice-matched conditions (0.42<1−x<0.52).

Supercritical fluid extraction of polychlorinated dibenzodioxins and dibenzofurans from soil samples

The extraction with supercritical CO 2 is compared with the well known soxhlet method in order to reduce the required time for the extraction of soil samples. In the first step of this study extractions were carried out using sand spiked with three chloroorganic compounds. In order to explore the influence of three variables on the recovery of these compounds the statistical method of factorial design was applied. Using the results of this investigation the optimum extraction conditions from soil samples were determined by means of the sequential simplex method. In these experiments the extractable organic halogen (EOX) was used as a rough estimation parameter. Finally the extraction of two soil samples was conducted in order to determine the concentration of polychlorinated dibenzodioxins (PCDD) and polychlorinated dibenzofurans (PCDF). The results of the trials with supercritical CO 2 were compared with the extraction data of the soxhlet method and they correspond well.

Simplex optimization of the analysis of polychlorinated biphenyls: Application to the resolution of a complex mixture of congeners of interest on a single gas chromatographic column

The modified sequential simplex method was applied to optimize the oven temperature programming of a single-column gas chromatography procedure developed to determine polychlorinated biphenyl congeners in a mixture of technical Aroclors. Both the overall resolution of fourteen congeners of interest and the time of analysis were taken into account in the optimization. Successful seperations of some clusters usually unresolved with a single column have been obtained.

Lineshape analysis for optical transitions in III-V semiconductors using a sequential simplex procedure

A computer lineshape analysis for optical transitions in III-V semiconductors is presented. The routine utilizes the Nelder–Mead version of the sequential simplex optimization procedure embodied in a pascal program that can be executed on a personal computer. The sequential simplex routine allowed the optimum fitting of experimental data with a function or group of functions with n-independent parameters. The routine was successfully applied to two types of optical spectra. First, convolved Gaussian and asymmetric Gaussian bands in low temperature (4.2 K) Fourier-transformed photoluminescence spectra of lattice-matched InxGa1−xAs on InP substrates were fit. As a result of applying the sequential simplex routine to the InxGa1−xAs/InP system, three optical transitions (excitonic band, donor-to-acceptor pair band, and defect/impurity or exciton LO replica band) were identified in all spectra and a fourth transition was found in some samples. A second application of the routine was the fitting of the Aspnes third derivative lineshapes (TDLS) to room temperature, low electric field photoreflectance spectra of high purity GaAs. In applying the routine to photoreflectance spectra, it was found that the two-dimensional critical point, n=3 form of the TDLS best fit the photoreflectance spectra of high-purity GaAs at room temperature. In both applications of the sequential simplex routine, the lineshape analysis contributed valuable insight into the nature of the optical phenomena occurring in the analyzed material.

Sequential Simplex Optimization

(1992). Sequential Simplex Optimization. Journal of Quality Technology: Vol. 24, No. 3, pp. 164-165.

Sequential Simplex Optimization, by F.H. Walters, L.R. Parker, Jr., S.L. Morgan and S.N. Deming

Sequential Simplex Optimization, by F.H. Walters, L.R. Parker, Jr., S.L. Morgan and S.N. Deming

Synthesis and activity optimization of herbicidal substituted 4-aryl-1,2,4-triazole-5(1H)-thiones

The process of sorting leads identified via screening can be made more eficient by the application of experimental design strategies. Such strategies were applied during the course of optimization of a series of 4-aryl-1,2,4-triazole-5(1H)-thiones which were initially identified as being herbicidal in greenhouse screens. Through application of a Free-Wilson strtegy and subsequent sequential simplex optimization, potency improvements of 25 000-fold over the unsubstituted phenyl compound have been realized in a hydroponic cucumber assay (...)

Modeling the postcure regime of ablative composite materials

Ablative polymer materials based on phenol-formaldehyde resins regardless of reinforcement or filler are the most frequently processed by compression molding at increased temperature. The prepared material is then postcured. The postcured process is optimized in time and temperature by the introduction of a nongradient optimization technique called Sequential Simplex Design (SSD). Once the local optimum is reached, mathematical modeling of the real optimum is obtained by using the Simplex-Sum Rotatable Design (SSRD) of the second order. The obtained regression model is adequate at 99 percent confidence level. The postcure regime does not depend on duration, but on the postcure temperature. 15 refs.

Herpes Simplex Virus Isolates from an Immunocompromised Patient who Failed to Respond to Acyclovir Treatment Express Thymidine Kinase with Altered Substrate Specificity

Ten sequential post-treatment herpes simplex virus type 1 (HSV-1) isolates were obtained from an immunocompromised patient whose infection, during prolonged treatment, became unresponsive to acyclovir (ACV). Of the ten isolates, eight later isolates were resistant in vitro to ACV and ganciclovir (DHPG), but remained sensitive to 9-β-D-arabinofuranosyladenine (ara-A) and phosphonoformate (PFA). Biochemical characterization of plaque-purified clones of the resistant isolates revealed an altered thymidine kinase (TK) substrate specificity phenotype. The comparative nucleotide sequence analysis of polymerase chain reaction (PCR)-amplified DNA encoding the TK genes of one sensitive and two resistant clones showed a single mutation at nucleotide 527. This change would result in a substitution of arginine by glutamine at residue 176 of the polypeptide, a mutation previously observed in a laboratory isolated variant, SC16 Tr7 (Darby et al., 1986).

Development and optimisation of a high-performance liquid chromatographic assay for tioconazole and its potential impurities : I. Selection of separation conditions

Statistical mixture design techiques have been utilized to develop an isocratic high-performance liquid chromatographic separation of 1-{2-(chloro-3-thienyl)-methoxy]-2-(2,4-dichlorophenyl)ethyl}-1H-imidazole (tioconazole) and its potential impurities. By using suitable quality criteria such as reduced plate height, peak asymmetry and selectivity for the interrogation of chromatograms the variables producing best column efficiency and greatest selectivity have been identified. The optimum separation for these variables has been located by the sequential simplex approach and confirmed by response surface mapping.

Optimization of the derivatization method for the liquid-chromatographic determination of carboxylic acids in wines

Several reagents and experimental conditions were tested to optimize the yield of the derivatization procedure for determining carboxylic acids in wines. Two techniques were applied for optimization: a modified sequential simplex method and a simultaneous modelling method. The results obtained were similar; advantages of the latter method are discussed. The optimized conditions (phenacyl bromide as reagent with 18-crown-6 as catalyst with a reaction time of 90 min at 90 ° C) were used to determine the main carboxylic acids in several varietal wines of the Tarragona region.