Search results for "Stability"
showing 10 items of 3085 documents
Inactivation kinetics of pectin methyl esterase under combined thermal–high pressure treatment in an orange juice–milk beverage
2008
Abstract The inactivation kinetics of PME in an orange juice–milk beverage system treated by thermal (65–80 °C) and combined thermal (25–65 °C)–high pressure (0.1–700 MPa) processes were fitted using a biphasic model. About 6–8% of the initial activity corresponding to the heat and pressure stable fraction was observed. For complete inactivation a treatment at 90 °C, 1 min or 700 MPa at 55 °C for 2 min was necessary showing the protective effect of the orange–milk media. The extent of inactivation was different in the orange matrices showing that PME was more thermostable in the orange juice–milk based beverage system as compared to the purified enzyme in a buffer system. On the other hand,…
Synthesis, characterization and thermal degradation of 8-hydroxyquinoline–guanidine–formaldehyde terpolymer
2007
Abstract Terpolymer (8-HQGF) has been synthesized using the monomers 8-hydroxyquinoline, guanidine, formaldehyde in 1:1:2 molar proportions. The structure of 8-HQGF terpolymer has been elucidated on the basis of elemental analysis and various physicochemical techniques, i.e. UV–Visible, FTIR–ATR and 1 H NMR spectroscopy. Detailed thermal degradation study of the new terpolymer has been carried out to ascertain its thermal stability. Thermal degradation curve is discussed which shows two decomposition steps (265–475 °C and 540–715 °C). Sharp–Wentworth and Freeman–Carroll methods have been used to calculate activation energies and thermal stability. The activation energy ( E a ) calculated by…
Helicobacter pylori and Epstein–Barr Virus Co-Infection in Gastric Disease: What Is the Correlation with p53 Mutation, Genes Methylation and Microsat…
2023
Genetic predisposition, environmental factors, and infectious agents interact in the development of gastric diseases. Helicobacter pylori (Hp) and Epstein–Barr virus (EBV) infection has recently been shown to be correlated with these diseases. A cross-sectional study was performed on 100 hospitalized Italian patients with and without gastric diseases. The patients were stratified into four groups. Significant methylation status differences among CDH1, DAPK, COX2, hMLH1 and CDKN2A were observed for coinfected (Hp-EBV group) patients; particularly, a significant presence of COX2 (p = 0.0179) was observed. For microsatellite instability, minor stability was described in the Hp-HBV group (69.23…
Generation of white LED light by frequency downconversion using a perylene-based dye
2012
A high efficiency white light emitting diode (LED) was fabricated by generation of frequency down-conversion from a GaN/InGaN blue LED. In place of conventional inorganic phosphors, a perylene-based dye was used for colour conversion. The resulting hybrid structure is analysed by focusing on the visual performance of the realised LEDs employing the most relevant photometric parameters of a light source. Preparation of the organic polymer is described as well. The thermal stability of the dye was investigated and a simple structure which avoids colour degradation is proposed.
Photoelectrical properties of thin films of DMABI derivatives
2011
Organic thin films with semiconducting properties have been intensively studied in nowadays due to very promising applications in organic electronics, for example, organic photovoltaic. Among organic semiconductors, group of indandiones with their photoelectrical properties, thermal and chemical stability are good candidates for use in design of novel molecular electronic devices. We have investigated photoconductivity quantum efficiency and its spectral dependence of two dimetilaminobenzylidene-1,3-indandione derivatives. Values of the photoconductivity threshold energy and optical energy gap are obtained. These results are compared with calculated transfer energy gap estimated according t…
Risk committee complexity and liquidity risk in the European banking industry
2021
Abstract The present study aims to investigate how bank governance characteristics are related to liquidity risk by analysing board composition, gender, and the risk committee. A dynamic panel data model is employed on a sample of European banks during the period after the financial crisis (from 2011 to 2017). Furthermore, we collect information about the profiles of the directors on the boards of banks, thereby creating five categories of risk committee members. To address the endogeneity issue, a generalised method of moments two-step estimator is implemented. The findings highlight that the fundamental role of the risk committee adequately shields banks against general liquidity risks. M…
Correlation, hierarchies, and networks in financial markets
2010
We discuss some methods to quantitatively investigate the properties of correlation matrices. Correlation matrices play an important role in portfolio optimization and in several other quantitative descriptions of asset price dynamics in financial markets. Specifically, we discuss how to define and obtain hierarchical trees, correlation based trees and networks from a correlation matrix. The hierarchical clustering and other procedures performed on the correlation matrix to detect statistically reliable aspects of the correlation matrix are seen as filtering procedures of the correlation matrix. We also discuss a method to associate a hierarchically nested factor model to a hierarchical tre…
Sense of coherence and work characteristics: A cross-lagged structural equation model among managers
2004
This study investigated the dominance of predictive relationships between Sense of Coherence (SOC) and work characteristics (organizational climate and job control) in cross-lagged longitudinal data with two measurement points and a time lag of 3 years. The sample consisted of 615 (587 men and 28 women) managers, aged between 27 and 64 years. The cross-lagged longitudinal analysis was done by the use of Structural Equation Modelling (SEM) within the framework by LISREL. The results of the chi-square difference tests indicated that the model where SOC at Time 1 predicted work characteristics at Time 2 better accounted for the data than the competitive models. However, the only significant pa…
Public sector wage premium and output volatility in the European Union
2018
This study seeks to uncover the role played by the public sector wage premium in explaining the output volatility. Furthermore, the study also explores the factors that might substantiate the cross-country differences in the volatility of the public sector wage premium. Using cross-sectional regression analysis for the European Union countries, the findings indicate that more volatile public sector wage premium is associated with higher fluctuations in the private sector employment and less stable growth. Findings also suggest that volatility of the public sector wage premium tends to be larger in countries with smaller governments and in countries where collective bargaining is the predomi…
Multi-wave, multi-variable models of job insecurity: applying different scales in studying the stability of job insecurity
2001
The study had two specific targets: first, to examine the stability of job insecurity by utilizing three-year longitudinal data (n = 109) collected in Finland and, second, to clarify psychometric properties of four job insecurity scales, i.e., the global scale, the importance scale, the probability scale and the powerlessness scale. The study was carried out by means of questionnaires, which were answered on three occasions. Analyses were conducted using multi-wave, multi-variable models which were estimated and tested via the LISREL program. Generally, the results showed that job insecurity remained relatively stable during the follow-up period, although there were some variations in the s…