Sacarificação enzimática do bagaço da cana-de-açucar pré-tratado com peróxido de hidrogênio adicionado de álcali ou cinzas

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Química, Florianópolis, 2013.Nos últimos anos tem surgido um grande interesse mundial no desenvolvimento de tecnologias que consigam aproveitar resíduos lignocelulósicos para obtenção de açúcares fermentescíveis. O bagaço da cana-de-açúcar é o principal resíduo agroindustrial do Brasil. Por mais que o bagaço seja empregado para geração de energia, grandes excedentes continuam sem aplicação. No entanto, o bagaço apresenta uma natureza recalcitrante, devido ao arranjo estrutural formado pelos seus componentes celulose, hemicelulose e lignina. Com isso, se torna necessário uma etapa de pré-tratamento para desprender a lignina e hemicelulose fazendo com que a celulose seja liberada e esteja acessível para as enzimas celulases. Partindo desta premissa, este trabalho estudou o pré-tratamento do bagaço da cana-de-açúcar para uma sacarificação enzimática eficiente. Para tanto, foram avaliados dois métodos de pré-tratamento: um utilizando o peróxido de hidrogênio alcalino como um processo padrão e outro utilizando o peróxido de hidrogênio suplementado com cinzas (objeto de estudo do presente trabalho). Para ambos pré-tratamentos, foram determinados as melhores condições de execução através de planejamentos experimentais, avaliando as variáveis: temperatura, concentração de H2O2, agitação, concentração de cinzas e por fim o tempo reacional, obtendo como superfície de resposta o rendimento de açúcares redutores liberados durante a hidrólise enzimática. Posteriormente, foram realizadas análises de composição e identificação de estruturas químicas e caracterização morfológica no bagaço antes e após os pré-tratamentos. A melhor condição para o pré-tratamento com peróxido de hidrogênio alcalino foi de 9,39% (v/v) H2O2, 46°C de temperatura e agitação de 1,67 Hz por um período reacional de 40 minutos. Já para o pré-tratamento com peróxido de hidrogênio suplementado com cinzas, a condição de 6,32% (v/v) H2O2, 3,40% (p/v) cinzas, 60°C de temperatura e agitação de 1,67 Hz por um período reacional de 2 horas foi a condição adequada. O rendimento de açúcares redutores após 48 horas de hidrólise enzimática para o pré-tratamento com peróxido de hidrogênio alcalino foi de 217,6 mg g-1 bagaço e de 179,9 mg g-1 bagaço para o pré-tratamento com peróxido de hidrogênio suplementado com cinzas, enquanto que para o bagaço não tratado foi de apenas 74,3 mg g-1 bagaço, enquanto que o rendimento de glucose foi o mesmo para os dois pré-tratamentos, mostrando que possuem a mesma eficiência. Ambos pré-tratamentos não apresentaram modificações significativas na estrutura química do bagaço antes e após pré-tratamento. Além disso, foi possível observar uma pequena desorganização física nas fibras do bagaço. Ambos pré-tratamentos possuem a mesma eficiência no rendimento de glucose, no entanto, o pré-tratamento com peróxido de hidrogênio alcalino apresenta formação de resíduos cáusticos envolvendo uma etapa de lavagem dispendiosa e com geração de efluente, além de promover parcial degradação da hemicelulose. Desta forma o pré-tratamento com peróxido de hidrogênio suplementado com cinzas apresenta-se mais viável para uma aplicação amigável ao meio ambiente.Abstract : In the last years there is a worldwide emerging interest in the development of technologies that are able to take advantage of lignocellulosic residues to obtain fermentable sugars. The sugarcane bagasse is the principal agroindustrial residue from Brazil. Although the bagasse is used for power generation, large surplus remains still without application. Its recalcitrant nature, due to the arrangement formed by the structural components cellulose, hemicellulose and lignin, makes necessary a pretreatment step to release cellulose from lignin and hemicellulose permitting, then, cellulase enzymes to access the molecules. This work studied the efficiency of two pretreatments of the sugarcane bagasse in promoting the enzymatic saccharification: one using alkaline hydrogen peroxide as a standard process and another using hydrogen peroxide supplemented with ash. For both pretreatments, the best operational conditions were evaluated using experimental design. The variables studied were temperature, H2O2 concentration, agitation, ash concentration and reaction time; the response variable was reducing sugars released during enzymatic hydrolysis. Modifications promoted on the bagasse by the pretreatments were evaluated by analysis of chemical composition, identification of chemical structures and morphological characterization, before and after pretreatments. The best condition found for the hydrogen peroxide alkaline pretreatment was 9.39% (v/v) H2O2, 46°C temperature and stirring of 1.67 Hz for a reaction time of 40 minutes, and for hydrogen peroxide supplemented with ash pretreatment, the best condition was 6.32% (v/v) H2O2, 3.40% (w/v) ash, 60°C and 1.67 Hz stirring for a reaction time of 2 hours. The yield, expressed in reducing sugars, after 48 hours of enzymatic hydrolysis for the alkaline hydrogen peroxide pretreatment was 217.6 mg g-1 bagasse, and 179.9 mg g-1 bagasse for hydrogen peroxide ash pretreatment; the untreated bagasse gave 74.3 mg g-1 bagasse yield, whereas the yield of glucose was the same for both pre-treatment, showing that have the same efficiency. Both pretreatments showed no significant changes in the chemical structure of the pulp before and after pretreatment. Moreover, we observed a small physical clutter in the fibers of bagasse. Both pretreatments have the same efficiency in the yield of glucose, however, pretreatment with alkaline hydrogen peroxide shows formation of caustic residues involving an expensive step wash and worth generation of effluent, besides promote partial degradation of hemicellulose, therefore the pretreatment with hydrogen peroxide supplemented with ash appears more feasible for implementation

Loneliness Across the COVID-19 Pandemic: Risk Factors in Norwegian Young People.

BACKGROUND: There is evidence of increasing levels of loneliness in Norwegian young people before the COVID-19 pandemic. It is not clear how the COVID-19 pandemic, and the associated necessary restrictions, impacted on these trends. AIMS: To examine how loneliness in young people changed across the pandemic, how loneliness relates to demographic characteristics and how different pandemic restrictions impacted loneliness. METHOD: We analyzed data from three waves of a Norwegian national higher education student survey (the SHoT-study). Data was examined from 2018 from a total of 49,836 students, 2021 from 62,212 students, and from 2022 from 53,362 (response rates 31-35%). Loneliness was measured by The Three-Item Loneliness Scale (T-ILS). RESULTS: There was a sharp increase in loneliness from 2018 to 2021, and a reduction in levels of loneliness in 2022, although at increased levels compared to prior to the pandemic. Females consistently report higher levels of loneliness than males, with a larger difference during the peak of the pandemic. There were higher rates of loneliness in geographical regions with higher COVID rates and greater pandemic-related restrictions during 2021. Loneliness was lower among students reporting more days on campus in 2021 and for those with lectures on campus in 2022, both with dose-response associations. CONCLUSIONS: Loneliness is a major public health problem among young adults in higher education. Loneliness increased during the pandemic and has decreased but is still not back to pre-pandemic levels. The results suggest the importance of open campuses and in-person lectures, for increased social connectedness among young people

Cannabis use among Norwegian university students: Gender differences, legalization support and use intentions, risk perceptions, and use disorder

Aims We explored past-year cannabis use and associated characteristics, focusing on legalization attitudes, use intentions, risk perceptions, and possible dependence among Norwegian university/college students. Methods We examined a nation-wide sample of Norwegian university/college students (N = 49,688; 67% female) who participated in the Students’ Health and Wellbeing Study (SHoT-study) in 2018. Participants reported past-year substance use, support for cannabis legalization, intent to use cannabis if legal, and perceived risks of weekly use. Past-year cannabis use (including use frequency) was examined in relation to these indicators. Legalization support, use intentions, and risk perceptions were examined in relation to use and gender. Potential cannabis use disorder was assessed with the Cannabis Abuse Screening Test (CAST) and examined in relation to use frequency and gender. Findings Past-year use was reported by 15.3% (11.8% women; 22.9% men). Majority of current users (roughly 90%) used no more than 50 times past year, and 6% (3.8% women; 8.5% men) met CAST use disorder criteria. Legalization support, use intentions, and no/low risk perceptions were significantly associated with greater odds of use, and greater use frequency among current users in both crude and adjusted models. Legalization support (23.0%), use intentions (14.0%), and perceptions of no/low risk (29.2%) were also relatively common even among current non-users, especially men. Male gender and more frequent use were associated with greater CAST scores and greater odds of use disorder. Conclusions Cannabis use was relatively common in this student sample. In addition to targeting frequent use, interventions may focus on cannabis-related attitudes and risk perceptions among uncertain/uninformed students.publishedVersio

Only the Lonely: A Study of Loneliness Among University Students in Norway

Background: Loneliness is a major public health concern among college and university students, the evidence is inconsistent regarding whether there is an increasing trend or not. Furthermore, knowledge of the demographic determinants for loneliness are limited. The present study assesses recent trends of loneliness from 2014 to 2018, and explores demographic risk indicators of loneliness among students. Method: Data was drawn from two waves of a national student health survey from 2014 and 2018 for higher education in Norway (the SHoT-study). In 2018, all 162,512 fulltime students in Norway were invited to participate and 50,054 students (69.1% women) aged 18-35 years were included (response rate = 30.8%). Loneliness was measured by “The Three-Item Loneliness Scale” (T-ILS) and one item from the Hopkins Symptom Checklist-25 (HSCL-25). Results: Age showed a curvilinear association with loneliness, with the youngest and oldest students reporting the highest level of loneliness across all measures. Other significant demographic determinants of loneliness were being female, single and living alone. There was a considerable increase in loneliness from 2014 (16.5%) to 2018 (23.6%, p < .001), and the increase was particularly strong for males, for whom the proportion of feeling “extremely” lonely had more than doubled. Conclusion: The high rate of loneliness and the increasing trends indicate the need for preventive interventions in the student population.publishedVersio

INOVAÇÃO, GESTÃO DO CONHECIMENTO E DISSEMINAÇÃO DE INFORMAÇÕES: SAC DA ESCOLA DO LEGISLATIVO/SC

Este artigo delimita-se em apresentar a proposta de implantação do Serviço de Atendimento ao Catarinense/SAC no intuito de inovar o gerenciamento de informações na Escola do Legislativo Catarinense. O objeto de estudo será o tratamento das informações no setor de atendimento. Para tanto, o ensaio tem como norteadores os preceitos da gestão do conhecimento, da inovação e da gestão da mudança aplicados à organização pública

Suicide attempts and non-suicidal self-harm among university students: prevalence study

Background: Suicide attempts and non-suicidal self-harm (NSSH) are major public health concerns that affect millions of young people worldwide. Consequently, there is a strong need for up-to-date epidemiological data in this population. Aims: To provide prevalence and trend estimates of suicidal thoughts and behaviours and NSSH thoughts and behaviour in university students. Method: Data are from a 2018 national health survey for higher education in Norway. A total of 50 054 full-time students (69.1% women) aged 18–35 years participated (response rate 31%). Suicidal ideation, suicide attempts and NSSH were assessed with three items drawn from the Adult Psychiatric Morbidity Survey, and thoughts of NSSH were assessed with one item from the Child and Adolescent Self-Harm in Europe study. Results: Lifetime suicidal thoughts were reported by 21.0%, and 7.2% reported having such thoughts within the past year. In total, 4.2% reported a suicide attempt, of whom 0.4% reported attempting suicide within the past year. The prevalence of lifetime NSSH behaviour and thoughts was 19.6% and 22.6%, respectively. All four suicidal behaviour and NSSH variables were more common among students who were single, living alone and with a low annual income, as well as among immigrants. There was an increase in suicidal thoughts from 2010 (7.7%) to 2018 (11.4%), which was evident in both men and women. Conclusions: The observed high and increasing prevalence of suicidal thoughts and NSSH among college and university students is alarming, underscoring the need for further research, preferably registry-linked studies, to confirm whether the reported prevalence is representative of the student population as a whole

Bioprospection of cellulolytic and lipolytic South Atlantic deep-sea bacteria

Background: Cellulases and lipases have broad industrial application, which calls for an urgent exploration of microorganisms from extreme environments as valuable source of commercial enzyme. In this context, the present work describes the bioprospection and identification of deep-sea bacteria that produce cellulases and lipases, as well their optimal temperature of activity. Results: The first step of this study was the screening of cellulolytic and lipolytic deep-sea bacteria from sediment and water column, which was conducted with substrates linked with 4-Methylumbelliferyl. Among the 161 strains evaluated, 40 were cellulolytic, 23 were lipolytic and 5 exhibited both activities. Cellulolytic and lipolytic bacteria are more common in sediment than at the water column. Based on the ability to produce cellulases and lipases three isolates were selected and identified (16S rRNA sequencing) as Bacillus stratosphericus , B. aerophilus and B. pumilus . Lipases of strain B. aerophilus LAMA 582 exhibited activity at a wide temperature range (4\uba to 37\ubaC) and include psychrophilic behaviour. Strain Bacillus stratosphericus LAMA 585 can growth in a rich (Luria Bertani) and minimal (Marine Minimal) medium, and does not need an inducer to produce its mesophilic cellulases and lipases. Conclusions: Deepsea sediments have great potential for bioprospection of cellulase and lipase-producing bacteria. The strains LAMA 582 and LAMA 585 with their special features, exhibit a great potential to application at many biotechnology process