Catalytic Upgrading of Softwood Kraft Lignin to Value Added Chemicals

Les forêts constituent la première des ressources naturelles du Canada et le développement d’une industrie forestière compétitive l’une des pierres angulaires de son économie. Cette dernière fait toutefois face à de sérieux défis depuis quelques années. L’augmentation des émissions de gaz à effet de serre révèle la nécessité de développer des bio-raffineries plus durables dont la rentabilité économique dépend grandement de l’usage qui peut être fait de la lignine, qui représente jusqu’à 40% de la masse totale des plantes. La lignine est un bio-polymère aromatique tridimensionnel constitué de blocs phénylpropèniques connectés par différents types de liaisons : b-O-4, 5-5, b-b 0 et 4-O-5. L’industrie des pâtes et papiers rejette, comme déchets, de larges quantités de cette lignine qui pourraient être valorisés en produits chimiques ou en hydrocarbures. La structure complexe et l’hétérogénéité de la lignine sont les principaux obstacles à son utilisation industrielle. Un débouché prometteur serait la production de biomatériaux tels que les composites en fibres de carbones, les fibres, les polyuréthanes, etc. Toute la lignine rejetée par les bio-raffineries ou l’industrie des pâtes et papiers n’est toutefois pas adaptée pour la synthèse de biomatériaux, sa conversion en hydrocarbures ou en produit chimiques est donc un sujet d’actualité. L’hydrogénolyse, l’hydrodésoxygénation, l’oxydation et la pyrolyse sont les principales méthodes de valorisation de la lignine. Compte tenu du faible prix des hydrocarbures et des composés aromatiques, la synthèse d’acides utiles pour l’industrie constitue notre principal objectif. La coupure oxydante des cycles aromatiques de la lignine produit des acides dicarboxyliques qui ont des applications dans les polymères ainsi que dans les industries pharmaceutiques et alimentaires et représentent donc un marché important mais peu abordé dans la littérature. Notre approche consiste dans l’emploi, pour la première fois, d’un système gaz-solide pour l’oxydation partielle de la lignine en acides carboxyliques sur un catalyseur hétérogène. Nous nous sommes concentrés sur l’introduction du catalyseur dans un microréacteur à lit fluidisé, sur l’optimisation du procédé et sa modélisation cinétique pour déboucher sur une nouvelle méthode prometteuse pour l’oxydation partielle de lignine en produits chimiques. Dans la première partie de cette thèse, nous identifions un nouveau système hétérogène gaz-solide-liquide pour la conversion de lignine en acides carboxyliques. Un sujet qui est abordé dans le troisième chapitre consacré à l’oxydation partielle de lignine en acides carboxyliques sur du vanadium pyrophosphate et de l’Al-V-Mo en phase gaz ("Gas phase partial oxidation of lignin to carboxylic acids over vanadium pyrophosphate and Al-V-Mo "). Une pompe seringue atomise une solution alcaline de lignine dans un micro-lit-fluidisé catalytique opérant au-dessus de 300 °C. Les catalyseurs hétérogènes à base de vanadium sont les plus actifs pour casser les liaisons de la lignine, vii ouvrir les cycles aromatiques et oxyder sélectivement la lignine en aromatiques et en acides carboxyliques dont le rendement est principalement affecté par la température et le ratio C :O2. Le système souffre d’un faible rendement et d’un taux de désactivation du catalyseur important mais notre séquence d’injection de la lignine a permis de maintenir la conduite propre de façon ininterrompue pendant plusieurs heures, de réduire la formation de coke et la désactivation du catalyseur tout en améliorant le rendement en composés organiques à hauteur de 25 %. Un contact direct entre les, grandes, molécules de lignines et le catalyseur accélère la désactivation de ce dernier. Une désactivation qui peut aussi être causée par la solution alcaline, par les impuretés présentes dans la lignine ou par l’eau. Les dégradations thermiques et oxydatives sont deux des méthodes pour convertir la lignine en produits chimiques dont une grande part est condensable et dont la séparation est donc coûteuse. Ces inconvénients nous ont conduits à introduire un nouveau système qui fait l’objet de la seconde partie de cette thèse consacrée à la conversion directe et sélective de ces vapeurs en produits chimiques. Nous y caractérisons les conversions et les sélectivités des produits de la lignine dans un microréacteur à lit-fluidisé opérant jusqu’à 600 °C et y modélisons les mécanismes de sa dégradation à l’aide d’analyses thermogravimétriques avec des taux de chauffages de 5Kmin−1 à 30Kmin−1 (Chapitre 4). C’est un domaine où les données expérimentales sont rares, en particulier en ce qui concerne l’oxydation de la lignine. Le rendement en produits liquides (majoritairement des aromatiques) est d’environ 20% dans les deux cas. Dans l’air, l’oxygène réagit avec la lignine pour former du CO, du CO2 et du CH4 alors que le noir de carbone est majoritaire dans le nitrogène. Un modèle à deux étapes décrit correctement le taux de dégradation. Il y a, durant l’oxydation, une compétition entre la formation de gaz et de liquides et la conversion du liquide en gaz via une nouvelle oxydation. Dans la pyrolyse, le noir de carbone provient de la repolymérisation des produits phénoliques formés. L’oxydation catalysée et sélective de ces monomères en produits chimiques est le sujet de notre cinquième chapitre. Pour cela, nous avons introduit un système semi-discontinu en deux étapes incluant le craquage thermo-oxydant de lignine suivi par une régénération du catalyseur avec l’oxydation des résidus carbonés. La lignine se dégrade graduellement avec l’augmentation de la température. Les aromatiques produits passent au travers du lit catalytique où ils s’oxydent partiellement de façon sélective. Dans un premier temps, nous avons considéré quatre configurations de réacteurs pour étudier l’effet de l’oxygène et de la vapeur d’eau sur la dégradation de la lignine et par conséquent sur le rendement final. La conversion de la lignine en composés liquides, sur la base d’un bilan carbone, est plus importante en présence d’eau et d’oxygène, les conditions oxydantes améliorent donc le rendement avec un catalyseur VPO. Toute la lignine se convertit en liquide ou en gaz. La formation de coke est considérablement réduite. Nous avons ensuite synthétisés et testés différents catalyseurs pour identifier des matériaux viii actifs pour la conversion de lignine en acides carboxyliques. Le catalyseur de vanadium favorise principalement la transformation de lignine en acide maléique. Le choix du support affecte le rendement et la distribution des produits. Les catalyseurs basiques sont moins actifs que ceux acides pour la dégradation de la lignine. Nous avons aussi testé la transformation de lignine non purifiée, celle qui est directement produite par les industries de pâtes et papiers et les bio-raffineries. Le résultat est comparable à celui obtenu à partir de lignine pure. Il est intéressant que les impuretés n’affectent pas la méthode et qu’elles accroissent même parfois la sélectivité en acides. Finalement nous avons analysé les effets de la concentration initiale en O2 et en eau et ceux du temps de résidence t sur le rendement en produits liquides et gazeux ainsi que sur la sélectivité des produits dans le cas du catalyseur TiO2-WO3, un catalyseur qui a une bonne sélectivité pour l’acide butyrique (Section 6). Nous avons développé un modèle cinétique pour décrire le procédé d’oxydation catalytique et évaluer l’influence des conditions opératoires initiales sur l’oxydation catalytique de lignine dont les paramètres sont déterminés à l’aide d’une analyse locale. L’effet des paramètres considérés sur le rendement de la réaction a lui aussi été étudié. Une plus grande concentration en oxygène augmente le ratio de liquide sur gaz (de > 10 %) et favorise les composés aromatiques de petite taille. Pour convertir ce liquide en acide butyrique, moins de 5% d’oxygène est requis lorsque t est supérieur à 0.5 s. Une augmentation du temps de résidence améliore la sélectivité en acide butyrique. À l’aune des connaissances acquises lors de cette étude, nous pouvons introduire l’oxydation partielle de lignine dans un réacteur gaz-solide à lit fluidisé comme une nouvelle approche pour la transformation de la lignine en composés valorisés et en particuliers en acides carboxyliques. Dans les systèmes gaz-solide-liquide, la lignine est introduite lentement dans le lit où elle est directement en contact avec le catalyseur, elle s’évapore et s’oxyde, à la surface du catalyseur ou dans le lit, en composés aromatiques et en acides carboxyliques. Dans les systèmes gaz-solides, la dégradation thermo-oxydative de la lignine génère des vapeurs qui sont oxydées sélectivement en acides carboxyliques. Le catalyseur acide à base de vanadium, molybdène et tungstène supportés sur Al2O3, HZSM-5, TiO2 a démontré des performances prometteuses pour la conversion de lignine en produits chimiques fins et en acides dicarboxyliques, spécialement ceux en C4. Cependant, l’activité et la sélectivité du catalyseur affecte le rendement et la distribution en produits liquides. Il en va de même pour la température, la concentration d’O2 et celle d’eau/vapeur. Le modèle cinétique local proposé est simple mais prédit correctement la conversion de lignine, sa sélectivité et les effets des différents paramètres. En plus de la lignine purifiée, celle impure directement produite par l’industrie peut être utilisée pour ce procédé, particulièrement dans le cas du réacteur gaz-solide. Le sous-produit de la méthode est du gaz de synthèse qui peut être converti en hydrocarbures ou en produits chimiques par des procédés déjà connus et employés. ---------- Forests are the most significant of Canada’s resources. Establishing the forest industry is one of the cornerstones of the Canadian economy. However, it has been facing unexpected challenges for the past few years. The increase in the emission of greenhouse gases demonstrate the need for developing sustainable bio-refineries. The use of lignin, which constitutes up to 40% of total plant mass, has a crucial effect on viability of bio-refineries. Lignin is a three-dimensional aromatic bio-polymer consisting of phenylpropene units that are connected together with various linkages such as b-O-4, 5-5, b-b0 and 4-O-5. The pulp and paper industry produces a huge amount of lignin as waste. Hence it can serve as a potential feedstock to produce materials, fuel and chemicals. The complex structure of lignin and its heterogeneity are the barriers to the industrial scale usage of lignin. The production of bio-material such as carbon fiber composite materials, fibers, polyurethane etc. are promising lignin products. However, all remaining lignin from bio-refineries or pulp and paper industries are not suitable for bio-material application. Hence the utilization of this abundant lignin is valuable for conversion to fuels and chemicals. Hydrogenolysis, hydrodeoxygenation, oxidation and pyrolysis are the most common used ways to upgrade lignin. Due to the cheaper price of fuels and aromatic chemicals, our main aim is to focus on industrially important acids. The oxidative cleavage of lignin aromatic rings leads to dicarboxylic acids that could be used in polymer, pharmaceutical and food industries, and it may constitute a large market. However, there is little work on this in the literature. We approach this subject by employing a gas-solid heterogeneous system for the partial oxidation of lignin to carboxylic-acids in the presence of heterogeneous catalyst for the first time. We targeted the catalyst used, a micro fluidized-bed reactor, the optimization of the process, and kinetic modelling to pave a new avenue in the partial oxidation of lignin into fine chemicals. In the first step of this thesis, we identify a new gas-solid-liquid heterogeneous system for the conversion of lignin into carboxylic acids. In this regard, the third chapter of this thesis is devoted to the "Gas phase partial oxidation of lignin to carboxylic acids over vanadium pyrophosphate and Al-V-Mo ". A syringe pump atomized an alkaline lignin solution into a catalytic micro fluidized-bed operating above 300 °C. Among the synthesized heterogeneous catalysts, vanadium based catalysts were active to cleave lignin bonds, open aromatic rings and selectively oxidize lignin to carboxylic acids and aromatics. Both, temperature and the C:O2 ratio affect the yield of carboxylic acids. The system suffers from a low yield and a x high catalyst deactivation rate. To reduce the catalyst agglomeration, we modified the system with forced cycling catalyst regeneration. The sequence lignin injection helped to keep the line clear for several hours uninterrupted, reduced coke formation and catalyst deactivation rate, and increase the yield of organic compounds up to 25 %. The direct contact of huge lignin molecules with the catalyst accelerates, catalyst deactivation rate. Alkaline solution, lignin impurities and water can also deactivate catalysts. These disadvantages lead us to introduce a new system. Thermal and oxidative degradation are two methods for the conversion of lignin into chemicals. The condensible products constitute a wide range of chemicals, so their separation is costly. The direct conversion of these evaporates into selective chemicals is investigated in the second part of this thesis. We characterized the lignin product yield and selectivity in a micro-fluidized bed reactor operating up to 600 °C and modelled the degradation mechanism with use of thermogravimetric analysis at a heating rate of 5Kmin−1 to 30Kmin−1(Chapter 4). There is little data concerning these processes, particularly in lignin oxidation. The liquid product yield (predominantly aromatics) was ~ 20% for both cases. In air, oxygen reacted with lignin and mainly form CO, CO2 and CH4 while in nitrogen char was the principal product. A two-step model accurately described the degradation rate. During oxidation there is a competition between liquid and gas formation, and liquid converts to gas with further oxidation. In pyrolysis, char comes from the repolymerization of the formed phenolic. The selective catalytic oxidation of these monomers into chemicals is the topic of our fifth chapter. To do so, we introduced a two-step semi-batch system featuring the thermo-oxidative cracking of lignin, followed by a catalyst oxidation of volatiles. The lignin degraded gradually with an increase of temperature, and the produced aromatics were passed through the bed of the catalyst for selective partial oxidation. First, we considered four reactor configurations to study the effect of oxygen and water vapour in lignin degradation and consequently the final product yield. More carbon converted to liquid when lignin degrades in the presence of water and oxygen and consequently passed through VPO as an oxidative catalyst. All the lignin converted to liquid and gas, and coke formation was reduced considerably. Then we synthesized and tested various catalysts to identify the active material in the conversion of lignin to carboxylic acids. Vanadium catalysts mainly convert lignin to maleic acid, and catalyst supports change product distribution and yield. Basic catalysts were not as active as acidic catalysts in terms of the degradation of lignin. We also tested unwashed lignin, which is the direct product of the pulp and paper and bio-refinery industries. The result was comparable with pure lignin. Impurities did not affect this method, and were even found to increase acid selectivity to some extent. xi Finally, we screened the effect of initial O2 and water concentration and τ on the yield of liquid, gas and product selectivity for a TiO2-WO3 catalyst, which has a good selectivity to butyric acid (Section 6). We then developed a kinetic model to describe the catalytic oxidation process and evaluate the influences of operating conditions on the catalytic oxidation of lignin under initial reaction conditions. Last, we derive the kinetic parameters by using a lumped kinetic model. Higher oxygen concentration was found to increase the liquid to gas ratio (>10 %) and oxygen degrades lignin to smaller aromatic compounds. To convert this liquid to butyric acid, <5% oxygen is required when τ is higher than 0.5 s. In addition, an increase of residence time improves butyric acid selectivity. With the help of the insight gained in this study we can say that the partial oxidation of lignin in the gas-solid fluidized-bed reactor is a novel approach for upgrading lignin to value-added chemicals and in particularly carboxylic acids as an open chain product from lignin. In the gas-solid-liquid system, lignin was introduced to the bed slowly, directly contacted with the catalyst, evaporates, and oxidized on the surface of the catalyst or in the bed and converted to aromatic compounds and carboxylic acids. In the gas-solid system, thermo-oxidative degradation of lignin lead to vapours that are selectively oxidized to carboxylic acids. Acidic catalyst based on vanadium, molybdenum and tungsten on the Al2O3, HZSM−5, TiO2 demonstrated promising performance in the conversion of lignin to fine chemicals and dicarboxylic acids, especially C4 ones. However, catalyst activity and selectivity changes the liquid product yield and selectivity but reaction condition such as temperature, O2 concentration, and water/steam concentration have a considerable effect, as well. The proposed lumped kinetic model, however, was simple but accurately predicts lignin conversion, product selectivity and the effect of various parameters. Beside pure lignin, unwashed lignin can act as the feed for these processes, especially in gas-solid reactors. The by-product of the introduced method was syngas, which can be converted into fuel and chemicals

Gas-solid conversion of lignin to carboxylic acids

Lignin is the only source of aromatics from lignocellulosic biomass and is a potential alternative to petroleum as a sustainable source of chemicals . Lignin constitutes 15% to 40% of the dry weight of lignocellulose, but because its a complex heterogeneous molecule. Thermo-chemical processes break lignin down to light gases (CO, H2, CH4) and pyrolysis oils characterized by a wide range of compounds, which requires further processing. The challenge is to activate lignin at lower temperatures to reduce the yield of light gases and to target a narrow class of compounds. Catalysts can improve selectivity towards the target molecules at lower temperature but carbonaceous species coke the active sites within seconds and minutes. Here we describe a two stage reactor in which we oxidize and steam crack lignin in the first stage (at heating rate of 5°Cmin−1 up to 550°C) of lignin and catalytically oxidize the effluent in the second stage. We targeted carboxylic acids that have a higher market than biofuel. With a gas feed composition of 10% oxygen and 50% steam all the lignin reacted. In the second stage, vanadium catalyst cleaved the remaining lignin bonds and opened up aromatic rings to make carboxylic acids — mostly C4 acids. In the presence of vanadium pyrophosphate 24% of the lignin formed a condensable product of which 48% was maleic acid 31% C5-C8 aromatics and fumaric ,malonic and gallic acid. Only ∼ 5% of the lignin formed coke

Primary preventive interventions on traffic accidents among males: A review on the literature during 2009-2019 in Iran

Introduction: The present study aimed to compare the national health indicators and the effectiveness of primary preventive interventions on traffic accidents in Iran during the last decade (2009-2019). Methods: All published original articles on the primary preventive intervention and health indicators of traffic accidents in Iran were extracted. The inclusion criteria included epidemiologic studies on Iranian male population during 2009-2019. Data were screened and extracted by two independent evaluators and the quality of studies was checked using the&nbsp;STROBE&nbsp;checklist. The exclusion criteria included those articles aimed at presenting results of second or third levels prevention (including injury management, pre-hospital emergency management, economic analyses, case reports, and traffic accidents&nbsp;from non-human perspectives).&nbsp; Accident-related mortality rates, proportionate mortality from traffic accidents per 1000 vehicles, and per 1000 accidents were estimated. &nbsp;Results: A total of 65 original articles were included of which 13 were presented health indicators. The crude mortality rate varied from 57.1 in Sistan-Balooshestan province to 73 (per 100,000 population ) in Fars province.&nbsp; The age-standardized mortality rate among male pedestrians (per 100,000 population) varied from 10.6-33.4 in Gilan and Mazandaran, 42 in Fars, 50.9 in Lorestan provinces. During the last 10 years, the mortality rate decreased from 38 to 12 cases per 1000 vehicles and increased from 51 to 56 cases per 100 accidents. Studies on the effectiveness of primary level prevention have addressed regulations on controlling blood alcohol level and international projection models. &nbsp;Conclusions: The type of health indicators related to traffic accidents seems to vary greatly among studies. Investigation on the effectiveness of primary preventive interventions on traffic caccidents are proposed frequently by WHO. Nevertheless, short-term and long-term effectiveness of many interventions including educational packages, regulations and specific laws have not been assessed in Iran

Corneal collagen cross-linking effects on pseudophakic bullous keratopathy

AIM: To evaluate the efficacy of riboflavin administration and ultraviolet A(UVA)cross-linking on advanced symptomatic bullous keratopathy. <p>METHODS: Fifteen patients with symptomatic pseudophakic bullous keratopathy(PBK)were included. Slit-lamp examination, visual acuity, foreign body sensation(FBS)questionnaire, corneal clarity grading, ocular pain intensity scale and corneal thickness measures with Pentacam and ultrasound pachymetry(UP), were performed before corneal cross-linking and 1 and 6mo thereafter. After using sodium chloride solution, for one week, the central 8mm(diameter)of the corneal epithelium was removed, and cross-linking, with riboflavin instillation every 3min for 30min, and UVA irradiation for 30min was performed. <p>RESULTS: Five males and 10 females with mean age of 66±13y were included. Mean follow up time was 6.2mo. Corneal transparency in all eyes was statistically significantly better 1 month after treatment than preoperatively(<i>P</i><0.05). At 6mo, however, corneal transparency was better in 8 eyes, the same in 5 eyes, and worse in 2 eyes compared with preoperative levels(<i>P</i>= 0.218). Foreign body sensation subsided in 70% of patients. The average CCT decreased within 1mo after the procedure(<i>P</i><0.05). At 6mo, all but 3 eyes had progressive swelling, and the CCT increased; however, the CCT was still statistically significantly thinner than preoperatively(<i>P</i>=0.006). The improvement in mean CDVA from preoperatively to 1mo postoperatively was statistically significant(<i>P</i>=0.010). At 6mo, no significant differences were observed(<i>P</i>=0.130). The pain scores at 1mo were statistically significantly better than preoperatively(<i>P</i>=0.007). At 6mo, however the mean pain score was higher than at 1mo and not statistically significantly different from the preoperative score(<i>P</i>=0.070). <p>CONCLUSION: Corneal CXL significantly improved corneal transparency, corneal thickness, and ocular pain 1 month postoperatively. However, it did not seem to have a long-lasting effect in decreasing pain and maintaining corneal transparency in patients with PBK. This procedure extends the time interval for corneal transplantation and increases visualization at DSAEK procedure

Effects of home confinement on mental health and lifestyle behaviours during the COVID-19 outbreak:insights from the ECLB-COVID19 multicentre study

Although recognised as effective measures to curb the spread of the COVID-19 outbreak, social distancing and self-isolation have been suggested to generate a burden throughout the population. To provide scientific data to help identify risk factors for the psychosocial strain during the COVID-19 outbreak, an international cross-disciplinary online survey was circulated in April 2020. This report outlines the mental, emotional and behavioural consequences of COVID-19 home confinement. The ECLB-COVID19 electronic survey was designed by a steering group of multidisciplinary scientists, following a structured review of the literature. The survey was uploaded and shared on the Google online survey platform and was promoted by thirty-five research organizations from Europe, North Africa, Western Asia and the Americas. Questions were presented in a differential format with questions related to responses “before” and “during” the confinement period. 1047 replies (54% women) from Western Asia (36%), North Africa (40%), Europe (21%) and other continents (3%) were analysed. The COVID-19 home confinement evoked a negative effect on mental wellbeing and emotional status (P < 0.001; 0.43 ≤ d ≤ 0.65) with a greater proportion of individuals experiencing psychosocial and emotional disorders (+10% to +16.5%). These psychosocial tolls were associated with unhealthy lifestyle behaviours with a greater proportion of individuals experiencing (i) physical (+15.2%) and social (+71.2%) inactivity, (ii) poor sleep quality (+12.8%), (iii) unhealthy diet behaviours (+10%), and (iv) unemployment (6%). Conversely, participants demonstrated a greater use (+15%) of technology during the confinement period. These findings elucidate the risk of psychosocial strain during the COVID-19 home confinement period and provide a clear remit for the urgent implementation of technology-based intervention to foster an Active and Healthy Confinement Lifestyle AHCL)

Globally altered sleep patterns and physical activity levels by confinement in 5056 individuals:ECLB COVID-19 international online survey

Symptoms of psychological distress and disorder have been widely reported in people under quarantine during the COVID-19 pandemic; in addition to severe disruption of peoples' daily activity and sleep patterns. This study investigates the association between physical-activity levels and sleep patterns in quarantined individuals. An international Google online survey was launched in April 6th, 2020 for 12-weeks. Forty-one research organizations from Europe, North-Africa, Western-Asia, and the Americas promoted the survey through their networks to the general society, which was made available in 14 languages. The survey was presented in a differential format with questions related to responses "before" and "during" the confinement period. Participants responded to the Pittsburgh Sleep Quality Index (PSQI) questionnaire and the short form of the International Physical Activity Questionnaire. 5056 replies (59.4% female), from Europe (46.4%), Western-Asia (25.4%), America (14.8%) and North-Africa (13.3%) were analysed. The COVID-19 home confinement led to impaired sleep quality, as evidenced by the increase in the global PSQI score (4.37 +/- 2.71 before home confinement vs. 5.32 +/- 3.23 during home confinement) (p &lt; 0.001). The frequency of individuals experiencing a good sleep decreased from 61% (n = 3063) before home confinement to 48% (n = 2405) during home confinement with highly active individuals experienced better sleep quality (p &lt; 0.001) in both conditions. Time spent engaged in all physical-activity and the metabolic equivalent of task in each physical-activity category (i.e., vigorous, moderate, walking) decreased significantly during COVID-19 home confinement (p &lt; 0.001). The number of hours of daily-sitting increased by similar to 2 hours/days during home confinement (p &lt; 0.001). COVID-19 home confinement resulted in significantly negative alterations in sleep patterns and physical-activity levels. To maintain health during home confinement, physical-activity promotion and sleep hygiene education and support are strongly warranted.</p

Sleep Quality and Physical Activity as Predictors of Mental Wellbeing Variance in Older Adults during COVID-19 Lockdown:ECLB COVID-19 International Online Survey

Background. The COVID-19 lockdown could engender disruption to lifestyle behaviors, thus impairing mental wellbeing in the general population. This study investigated whether sociodemographic variables, changes in physical activity, and sleep quality from pre- to during lockdown were predictors of change in mental wellbeing in quarantined older adults. Methods. A 12-week international online survey was launched in 14 languages on 6 April 2020. Forty-one research institutions from Europe, Western-Asia, North-Africa, and the Americas, promoted the survey. The survey was presented in a differential format with questions related to responses "pre" and "during" the lockdown period. Participants responded to the Short Warwick-Edinburgh Mental Wellbeing Scale, the Pittsburgh Sleep Quality Index (PSQI) questionnaire, and the short form of the International Physical Activity Questionnaire. Results. Replies from older adults (aged &gt;55 years, n = 517), mainly from Europe (50.1%), Western-Asia (6.8%), America (30%), and North-Africa (9.3%) were analyzed. The COVID-19 lockdown led to significantly decreased mental wellbeing, sleep quality, and total physical activity energy expenditure levels (all p &lt; 0.001). Regression analysis showed that the change in total PSQI score and total physical activity energy expenditure (F-(2,F- 514) = 66.41 p &lt; 0.001) were significant predictors of the decrease in mental wellbeing from pre- to during lockdown (p &lt; 0.001, R-2: 0.20). Conclusion. COVID-19 lockdown deleteriously affected physical activity and sleep patterns. Furthermore, change in the total PSQI score and total physical activity energy expenditure were significant predictors for the decrease in mental wellbeing.</p

Prevalence of bullying and its relationship with trauma symptoms in young Iranian students

Objective Bullying and peer victimization in school are serious concerns for students,parents, psychologists, and school officials around the world. This descriptive study examinedbullying/victimization among Iranian students and the relationship between bullying andtrauma symptoms.Methods This study was a cross-sectional research and descriptive correlative study.Descriptive statistics and Pearson correlation were used to analyze the data. The RevisedOlweus Bully/Victim Questionnaire and Trauma symptoms checklist for children (TSCC-A)were administered to 591(325males and 266 females) students aged 10 to 14 year.Results The results revealed that 38.4 % of students reported bullying behavior. In addition,victims had the highest level of depression, anxiety, and anger compared to uninvolvedstudents. Bullies were not related to trauma symptoms.Conclusion Conclusions include detailed recommendations for further empirical studies

Ingénierie des Systèmes d'Information : Systèmes Collaboratifs et Réseaux Sociaux

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Bilateral Dentigerous Cysts in a Non-Syndromic Patient: Literature Review and Report of a Case

Introduction: Dentigerous cysts (DCs) are the most common developmental cysts of the jaws, mostly associated with impacted third molars and canines. Multiple or bilateral DCs are rare and typically occur in association with some syndromes including cleidocranial dysplasia and Gorlin-Goltz. The occurrence of multiple DCs is rare in the absence of these syndromes. Case Presentation: A 28-year-old male was referred for pain and mobility of the left mandibular second molar. On radiological examination, follicular enlargement in relation to the unerupted third molar was found. Another unilocular radiolucent area was seen in relation to the right-side unerupted third molar. A provisional diagnosis of multiple odontogenic keratocysts was made; however, the histopathological studies revealed DC on both sides. The patient’s medical history was non-significant, and no associated syndromes were present. Bilateral DCs are rare in the absence of a syndrome, and to date, only 53 cases have been reported in the literature. Here, we report the unusual bilateral occurrence of DCs associated with unerupted mandibular third molars in a non-syndromic patient with a review of the literature for this unusual finding. The one-year follow-up radiograph of the patient showed a favorable osseous formation with no evidence of recurrence of the cysts. Conclusion: A comprehensive radiographic examination, especially for mandibular third molars, is essential for correct diagnosis and management of the lesions. Further-more, systematic clinical examinations should be performed to rule out any associated syndrome