Effects of hot water pre-extraction on surface properties of bagasse soda pulp

In this work, the effects of hot water pre-extraction of depithed bagasse on the soda pulping and surface properties were studied. The conditions of hot water pre-extraction were: maximum temperature 170 °C, heat-up time 90 min, time at maximum temperature 10 min, and solid to liquor ratio (S:L) 1:8. Consequently, the pre-extracted and un-extracted bagasse chips were subjected to soda pulping at 160 °C for 1h with 11, 14 and 17% active alkali charge and an S:L of 1:5. The results showed that the hot water pre-extraction increased bagasse surface texture porosity by hemicellulose degradation. Therefore, the delignification was faster for pulping of pre-extracted samples. At a certain charge of alkali, pre-extracted samples showed higher screened yield and lower Kappa number. For instance, at 17% alkali charge, pre-extracted bagasse gave 11.3% higher pulp yield compared with the un-extracted ones. Inverse gas chromatography (IGC) results showed that the hot water pre-extraction changed the active sites on the bagasse surface, decreasing the dispersive energy and the basicity character, and affected the particle morphology. The pulping process decreased the hydrophobicity and the basicity of the bagasse surface. The surfaces of un-extracted and pre-extracted bagasse pulps had similar properties but different morphology. The pulps present higher surface area and permeability with more reactive capacity.info:eu-repo/semantics/publishedVersio

What explains socioeconomic inequalities in dental flossing? Cross-sectional results from the RaNCD cohort study

Introduction: The magnitude of or determinants underlying socioeconomic inequalities in the use of dental floss is poorly understood in Iran. This study aimed to measure and decompose socioeconomic inequalities in dental flossing in Ravansar, Iran. Methods: This cross-sectional study used data of 10002 individuals aged 35-65 years obtained from the Ravansar Non-communicable Disease (RaNCD) cohort study located in Kermanshah province, west of Iran.  Socioeconomic status was measured through an asset-based method and principal component analysis was carried out to determine the socioeconomic status (SES). The concentration index and curve were used to measure socioeconomic inequality in dental flossing. Decomposition analysis was also used to determine the main determinants that contribute to inequalities in dental flossing. Findings: Of 10,002 participants, 11.74% were found to use dental floss. The normalized CI for use of dental floss was 0.327 in the entire population, 0.323 in females and 0.329 in males, indicating that the use of dental floss is more concentrated among high-SES individuals. The decomposition analysis indicated that SES (50.58%) and level of education (44.90%) respectively contributed the most to this inequality. Place of residence (10.55%) and age group (2.7%) were the next main contributors, respectively. Conclusion: There are a low prevalence and a relatively high degree of pro-rich socioeconomic-related inequality in dental flossing among Iranian adults. Socioeconomic status, level of education and place of residence contributed the most to the observed inequalities in dental flossing. Policy interventions should consider these factors to reduce inequality in the use of dental floss and increase the prevalence of dental flossing. &nbsp

Measuring and Decomposing Socioeconomic Inequalities in Adult Obesity in Western Iran

Objectives Obesity is a considerable and growing public health concern worldwide. The present study aimed to quantify socioeconomic inequalities in adult obesity in western Iran. Methods A total of 10 086 participants, aged 35-65 years, from the Ravansar Non-communicable Disease Cohort Study (2014-2016) were included in the study to examine socioeconomic inequalities in obesity. We defined obesity as a body mass index ≥30 kg/m2. The concentration index and concentration curve were used to illustrate and measure wealth-related inequality in obesity. Additionally, we decomposed the concentration index to identify factors that explained wealth-related inequality in obesity. Results Overall, the prevalence of obesity in the total sample was 26.7%. The concentration index of obesity was 0.04; indicating that obesity was more concentrated among the rich (p<0.001). Decomposition analysis indicated that wealth, place of residence, and marital status were the main contributors to the observed inequality in obesity. Conclusions Socioeconomic-related inequalities in obesity among adults warrant more attention. Policies should be designed to reduce both the prevalence of obesity and inequalities in obesity by focusing on those with higher socioeconomic status, urban residents, and married individuals

Socioeconomic-related inequalities in oral hygiene behaviors: a cross-sectional analysis of the PERSIAN cohort study

Background Socioeconomic-related inequality in oral hygiene behaviors in Iran is poorly understood. This study aims to measure and decompose socioeconomic-related inequalities in oral hygiene behaviors among middle-aged and elderly adults in Iran. Methods A cross-sectional analysis was performed using data from the Prospective Epidemiological Research Studies in IrAN (PERSIAN), a large national cohort study. A total of 130,016 individuals aged 35 years and above from 17 cohort centers in Iran were included in the study. The normalized concentration index (C-n) was used to measure the magnitude of inequality in oral hygiene behaviors, i.e. brushing at least twice and flossing once daily, among middle-aged and elderly Iranian adults included in the cohort centers. Decomposition analysis was performed to quantify the contribution of each determinant to the observed inequality in oral hygiene behaviors. Results Totally, 65.5% of middle-aged and elderly adults brushed their teeth twice a day or more, 7.6% flossed at least once a day and 3.48% had both habits. The estimated C-n of the two habits combined, i.e. tooth brushing and dental flossing, for all provinces taken part in the PERSIAN cohort study was 0.399 (95% confidence interval [CI]: 0.383 to 0.417), indicating that the prevalence of the two habits combined is more concentrated among individuals with higher socioeconomic status. Inequality in oral hygiene behaviors was pro-rich in all cohort centers. The decomposition results suggested socioeconomic status as the main factor contributing to the overall inequality, followed by the level of education, and the province of residence. Conclusion A low prevalence of oral hygiene behaviors among middle-aged and elderly Iranian adults was observed. There was also a pro-rich inequality in oral hygiene behaviors among middle-aged and elderly adults in all cohort centers. These results suggest an urgent need for targeted policy interventions to increase the prevalence of preventive oral hygiene behaviors among the poor and less-educated middle-aged and elderly adults in Iran

Validity of Self-reported Hypertension and Factors Related to Discordance Between Self-reported and Objectively Measured Hypertension: Evidence From a Cohort Study in Iran

Objectives Self-reporting can be used to determine the incidence and prevalence of hypertension (HTN). The present study was conducted to determine the validity of self-reported HTN and to identify factors affecting discordance between self-reported and objectively measured HTN in participants in the Ravansar Non-Communicable Diseases (RaNCD) cohort. Methods The RaNCD cohort included permanent residents of Ravansar, Iran aged 35-65 years. Self-reported data were collected before clinical examinations were conducted by well-trained staff members. The gold standard for HTN was anti-hypertensive medication use and blood pressure measurements. The sensitivity, specificity, positive and negative predictive values, and overall accuracy of self-reporting were calculated. Univariate and multivariate logistic regression were used to examine the discordance between self-reported HTN and the gold standard. Results Of the 10 065 participants in the RaNCD, 4755 (47.4%) were male. The prevalence of HTN was 16.8% based on self-reporting and 15.7% based on medical history and HTN measurements. Of the participants with HTN, 297 (18.8%) had no knowledge of their disease, and 313 (19.9%) had not properly controlled their HTN despite receiving treatment. The sensitivity, specificity, and kappa for self-reported HTN were 75.5%, 96.4%, and 73.4%, respectively. False positives became more likely with age, body mass index (BMI), low socioeconomic status, and female sex, whereas false negatives became more likely with age, BMI, high socioeconomic status, smoking, and urban residency. Conclusions The sensitivity and specificity of self-reported HTN were acceptable, suggesting that this method can be used for public health initiatives in the absence of countrywide HTN control and detection programs

Decomposing socioeconomic inequality in poor mental health among Iranian adult population: results from the PERSIAN cohort study

Background Socioeconomic inequality in mental health in Iran is poorly understood. This study aimed to assess socioeconomic inequality in poor mental health among Iranian adults. Methods The study used the baseline data of PERSIAN cohort study including 131,813 participants from 17 geographically distinct areas of Iran. The Erreygers Concentration index (E) was used to quantify the socioeconomic inequalities in poor mental health. Moreover, we decomposed the E to identify factors contributing to the observed socioeconomic inequality in poor mental health in Iran. Results The estimated E for poor mental health was - 0.012 (95% CI: - 0.0144, - 0.0089), indicating slightly higher concentration of mental health problem among socioeconomically disadvantaged adults in Iran. Socioeconomic inequality in poor mental health was mainly explained by gender (19.93%) and age (12.70%). Region, SES itself, and physical activity were other important factors that contributed to the concentration of poor mental health among adults with low socioeconomic status. Conclusion There exists nearly equitable distribution in poor mental health among Iranian adults, but with important variations by gender, SES, and geography. These results suggested that interventional programs in Iran should focus on should focus more on socioeconomically disadvantaged people as a whole, with particular attention to the needs of women and those living in more socially disadvantaged regions. Keywords:Mental health; Socioeconomic inequality; Concentration index; Decompositio

Évaluation d'un nouveau procédé de blanchiment par le dioxyde de chlore en réacteur à déplacement de liqueur et comparaison avec les procédés batch conventionnels ou non conventionnels

Molinier, Jacques, président Gonthier, Yves, rapporteur Pascoal Neto, Carlos, rapporteur Larnicol, Pierre, examinateur Mortha, Gérard, co-directeur de thèse Lachenal, Dominique, directeur de thèseChlorine dioxide is the most common bleaching agent for chemical pulps. In batch process approximately 50% of oxidizing capacity of ClO2 is consumed in useless reactions with the primary reaction products. The reaction of ClO2 with model compounds and kraft pulp confirms that approximately 5 to 6 electrons of oxidation per C9 unit of lignin is sufficient for the complete reaction. The more ClO2 applied is consumed in secondary reactions which become more significant after degradation of the phenolic rings. The results also showed that the muconic acid structures react with ClO2. The reactivity depends on the temperature and the concentration. Dimethyl muconic acid reacts more rapidly with an exchange of 2 to 4 electrons according to the ClO2 charge. The rate of its reaction is similar to that of the non-phenolic rings reaction rate. Displacement bleaching makes it possible to limit secondary reactions due to separation of reaction products from the reaction zone. The hydrodynamic study made it possible to optimize the principal parameters of the formation of the fibre fixed bed and the efficiency of elimination of the reaction products by the flow. The results of the pulp delignification by displacement showed that this process does not more effective because of the chlorate formation, in spite of elimination the reaction products. However, delignification in system multi-batch, with a low charge at the first stage with an intermediate alkali extraction stage lead to reduce up to 40% the ClO2 consumption.Le dioxyde de chlore est le réactif le plus utilisé pour le blanchiment des pâtes chimiques. En système batch conventionnel, environ 50% du réactif est consommé dans des réactions inutiles intervenant à l'issue des premières étapes de délignification. L'étude des composés modèles de lignine et de la pâte kraft confirme qu'environ 5 à 6 électrons d'oxydation par unité C9 de la lignine sont suffisants pour assurer une réaction complète. Les réactions secondaires interviennent principalement après la dégradation rapide des groupements phénoliques libres. Parmi celles-ci, l'acide muconique et ses dérivés formés au cours des premières étapes réagit en échangeant 2 à 4 électrons, à une vitesse similaire à celles des unités non phénoliques de la lignine, dont l'élimination est également favorisée par l'acide hypochloreux intermédiaire. La limitation des réactions secondaires est possible en utilisant un réacteur à lit fixe de fibres, induisant un déplacement relatif de la liqueur par rapport aux fibres. L'étude hydrodynamique a permis de caractériser les paramètres du lit fixe (pertes de charge, dispersion axiale). Les résultats de blanchiment ont confirmé l'obtention d'une plus grande sélectivité des réactions organiques, mais une perte d'efficacité globale en raison d'une plus grande formation de chlorate. En revanche, fondé sur un principe similaire, le procédé multi-batch [DE(p)]n à charge divisée en réactif permet d'augmenter la sélectivité réactionnelle de 40%

Simulation of lignin degradation during chlorine dioxide delignification stage

International audienc

Identification of Quantitative and Qualitative Papermaking Parameters of OCC Pulp Fibers

Nowadays there is a great competition for the production of packaging paper from recycled fibers. But success in this competition depends on improving its strength properties. Thus when it comes to talk about recycled fiber, the first and most important challenge is to tailor it for pulp and papermaking. Quantitative and qualitative papermaking information of recycled papers will significantly help to achieve this objective. Therefore in current research, some of papermaking parameters such as: fiber length average and distribution, the kind and amount of pulp and also the existing quantity of starch in OCC pulp were studied. The results showed that its fibers length has uneven distribution and more than 85% of OCC fibers have the average length less than 1 millimeter in the range of 0.47-0.65mm. Undoubtedly, this uneven fiber length distribution and its low length average would decrease the strength properties of paper. Fiber staining analysis applying Graff ″C″ stain represented that main section of fibers approximately 72.91% is from kraft pulp, and mainly softwood resources (33.33%). Moreover, the amount of extracted starch was measured nearly 2.32±0.25%. It should be considered that in recycling process, this amount of starch can strongly affect the chemical charge balance in wet end section of paper machine