Search results for "Factorial"
showing 10 items of 253 documents
Construct validity of the LSB-50 in argentinean adults: cross-validation and factorial invariance
2015
El trabajo se propone aportar evidencias de validez referidas al Listado de Síntomas Breve (LSB-50; de Rivera y Abuín, 2012), instrumento psicométrico de screening para medir síntomas sicológicos, analizadas en una muestra de adultos argentinos. Los participantes fueron 1291 individuos distribuidos proporcionalmente según sexo (51% mujeres; 49% varones) con edades entre 18 y 89 años (M = 38.9, DE = 16.49). Se llevaron a cabo estudios de validación cruzada e invarianza factorial para examinar si un modelo de siete factores que se correspondía con siete escalas clínicas (Hipersensibilidad, ObsesionesCompulsiones, Ansiedad, Hostilidad, Somatización, Depresión, y Alteraciones del sueño) present…
CORRELATION BETWEEN THE CHEMICAL-PHYSICAL PROPERTIES OF CNT AND MACROSCOPIC PROPERTIES OF RELATED NANOCOMPOSITES: A STATISTICAL APPROACH
2014
In the frame of this work, two different samples of CNTs, namely CNT 1 and CNT 2, were synthesized [1] with different degree of purity and aspect ratio and used as fillers either without any treatment or after a plasma-oxidation, to prepare polycarbonate (PC)-based nanocomposites by melt mixing. The influence of plasma treatment, filler content and type of CNTs on the mechanical, dynamic-mechanical, and electrical properties of the materials was assessed by a two level full factorial design. The morphological analysis carried out by SEM and TEM evidenced the formation of a nanohybrid structure when oxidized CNTs were used as filler. Generally speaking, CNT 2 showed the best dispersion and t…
Breast cancer genome-wide association studies: there is strength in numbers.
2012
Breast cancer (BC) is a heterogeneous disease that exhibits familial aggregation. Family linkage studies have identified high-penetrance genes, BRCA1, BRCA2, PTEN and TP53, that are responsible for inherited BC syndromes. Moreover, a combination of family-based and population-based approaches indicated that genes involved in DNA repair, such as CHEK2, ATM, BRIP and PALB2, are associated with moderate risk. Therefore, all of these known genes account for only 25% of the familial aggregation cases. Recently, genome wide association studies (GWAS) in BC revealed single nucleotide polymorphisms (SNPs) in five novel genes associated to susceptibility: TNRC9, FGFR2, MAP3K1, H19 and lymphocyte-spe…
Improved model based on the Weibull distribution to describe the combined effect of pH and temperature on the heat resistance of Bacillus cereus in c…
2003
The effect of pH and temperature on the thermal inactivation of different strains of Bacillus cereus was modeled. Inactivation tests were carried out in carrot broth, following a full factorial design at four levels for temperature (from 90 to 105 degrees C, depending on the strain) and pH (6.2, 5.8, 5.2, and 4.7). Individual inactivation curves were analyzed by applying the Weibull model function (with percent discrepancy close to 20% for most cases), and the effects of pH and temperature on the scale parameter (designated D(beta)) and the shape parameter (beta) were also studied. Temperature and pH did not have a significant effect on the shape parameter (beta). The effect of temperature …
Comparison of simultaneous saccharification and fermentation and separate hydrolysis and fermentation processes for butanol production from rice straw
2020
Abstract Rice straw (RS) is one of the lignocellulosic wastes with the highest global production. The main objective of this study was to maximise the butanol production by Clostridium beijerinckii DSM 6422 from RS pretreated by microwave-assisted hydrothermolysis. Two different fermentation strategies were compared: separate hydrolysis and fermentation (SHF, two-step process) and simultaneous saccharification and fermentation (SSF, one-step process). In parallel, the variables that significantly affected the butanol production were screened by using fractional factorial designs. Butanol concentration and productivity at 48 h were, respectively, 8% and 173% higher in SSF than in SHF. A one-…
Use of response factorial design for process optimization of basic dye adsorption onto activated carbon derived from Persea species
2017
Abstract Full factorial design is a powerful and efficient mathematical approach widely applied in the optimization of response. The important parameters which affect the removal efficiency of methylene blue such temperature, initial pH of the solution, concentration and adsorbent dosage were optimized. They coded as A, B, C and D, consecutively, and were investigated at two levels (+ 1 and − 1). A linear mathematical model representing the influence of the different variables and their interactions was obtained. Main effect, Normal probability plot of residuals, analysis of variance (ANOVA), surface plots, and contour plots were used to study the effects and interaction effects between ope…
Plasma non-cholesterol sterols: a useful diagnostic tool in pediatric hypercholesterolemia.
2010
Current guidelines strongly recommend the identification of genetic forms of hypercholesterolemia (HC) during childhood. The usefulness of non–cholesterol sterols (NCS) in the diagnosis of genetic HC has not been fully explored. Plasma NCS were measured by gas chromatography/mass spectrometry (GC/MS) in 113 children with hypercholesterolemia affected by: autosomal dominant hypercholesterolemia (ADH), familial combined hyperlipidemia (FCHL), polygenic hypercholesterolemia (PHC), and in 79 controls to evaluate: i) plasma NCS profile in different genetic HC and ii) the usefulness of NCS for the diagnosis of HC beyond current clinical criteria. ADH was characterized by raised lathosterol/total …
Enhanced extraction of isoflavonoids from Radix Astragali by incubation pretreatment combined with negative pressure cavitation and its antioxidant a…
2011
Abstract Incubation pretreatment with the function of endogenous enzyme combined with negative-pressure cavitation extraction (IP-NPCE) was established to extract calycosin and formononetin from Radix Astragali. Significant factors involved in the process were selected using Plackett–Burman factorial design (PBD) and then were optimized by central composite design (CCD). The optimum experimental conditions were incubation at 35 °C, 60 min, pH 4.0 and extraction at negative pressure − 0.080 MPa, ethanol concentration 60%, 60 mesh, 30 min, solid-to-liquid ratio 1:25 and two cycles. Under the optimal conditions, the extraction yields of calycosin and formononetin were 0.650 ± 0.015 and 0.307 ±…
Microwave-assisted extraction of polybrominated diphenyl ethers and polychlorinated naphthalenes concentrated on semipermeable membrane devices
2006
Abstract Microwave-assisted extraction (MAE) has been evaluated as an alternative to dialysis for the extraction of polybrominated diphenyl ethers (PBDEs) and polychlorinated naphthalenes (PCNs) sampled by semipermeable membrane devices (SPMDs), using gas chromatography coupled to tandem mass spectrometry (GC–MS–MS). For MAE optimization a two level full factorial design 2 3 , plus a centre point, which involves 11 randomized runs was used. The results showed that the temperature had a significant influence on the extraction of the nine PBDEs and four PCNs tested. Also, the solvent volume had a positive influence on the extraction of PBDEs and PCNs, but only in latter compounds, it achieves…
Development and validation of a micellar liquid chromatographic method to determine three antitumorals in plasma
2017
Aim: A micellar liquid chromatographic method to determine several anticancer drugs (pazopanib, dabrafenib and regorafenib) in plasma was developed and validated by the guidelines of the EMA. Experimental: Plasma samples were directly injected, after a 1/5-dilution in a micellar solution. The drugs were resolved in <18 min using a C18 column. The mobile phase was an aqueous solution of 0.12 M SDS – 2% 1-pentanol, buffered at pH 7. The detection was performed by absorbance at 260 nm. Results: The values of the main validation parameters were: LOD (0.1–1 mg/l), calibration range (0.2–2 to 80 mg/l), accuracy (-12.5 to +11.7%) and precision (<11.9%). Conclusion: The procedure was conduct…