Bibliografias temáticas / Gellan gum

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Literatura científica selecionada sobre o tema "Gellan gum"

Autor: Grafiati

Publicado: 4 de junho de 2021

Última modificação: 21 de fevereiro de 2023

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Artigos de revistas sobre o assunto "Gellan gum"

Giavasis, Ioannis, Linda M. Harvey e Brian McNeil. "Gellan Gum". Critical Reviews in Biotechnology 20, n.º 3 (janeiro de 2000): 177–211. http://dx.doi.org/10.1080/07388550008984169.

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Tran, Thi Phuong An, Hoon Cho, Gye-Chun Cho, Jong-In Han e Ilhan Chang. "Nickel (Ni2+) Removal from Water Using Gellan Gum–Sand Mixture as a Filter Material". Applied Sciences 11, n.º 17 (26 de agosto de 2021): 7884. http://dx.doi.org/10.3390/app11177884.

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Microbial biopolymers have been introduced as materials for soil treatment and ground improvement purposes because of their ability to enhance soil strength enhancement and to reduce hydraulic conductivity. Several studies in the field of environmental engineering have reported heavy metal adsorption and removal from contaminated water using common biopolymers. In particular, gellan gum biopolymers have drawn significant attention for use in metal ion adsorption. This study aims to investigate the heavy metal adsorption capacity of a gellan gum biopolymer–sand mixture when nickel-contaminated water is pumped upward through a uniform gellan gum–sand mixture column. The main aims of this study are (1) to clarify the Ni2+ adsorption phenomenon of gellan gum-treated sand, (2) to assess the Ni2+ adsorbability of gellan gum–sand mixtures with different gellan gum content, and (3) to examine the gellan gum–sand filter thickness and flow rate effects on Ni2+ adsorption. The results of this experiment demonstrate the effectiveness of gellan gum in terms of Ni2+ adsorption and water flow rate control, which are essential criteria of a filter material for contaminated water treatment.

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Sukumar, Soumiya, Santhiagu Arockiasamy e Moothona Manjusha Chemmattu. "Gellan gum biopolymer- A review". Research Journal of Chemistry and Environment 25, n.º 10 (25 de setembro de 2021): 150–57. http://dx.doi.org/10.25303/2510rjce150157.

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Gellan gum is an anionic polysaccharide produced by the bacterium Sphingomonas paucimobilis. Kaneko and Kang discovered the biopolymer in the laboratory of the Kelco Division of Merck and Co., California, USA. It is composed of tetrasaccharide repeating units of two residues of D-glucose, one of D-glucuronic and one of L-rhamnose. The functional properties of gellan gum make it one of the industrially useful exopolysaccharides. Sphingomonas paucimobilis ATCC 31461 is the bacterium used for the industrial production of gellan gum. The gellan gum has potential applications in food, pharmaceutical, biomedical and other industries. The gellan gum finds uses in the bioremediation field. Bioaugmentation of contaminated aquifers, biodegradation of hydrocarbons and the removal of dyes from wastewater are a few of its applications. This review provides an overview of the characteristics, production of gellan gum and recent bioremediation applications.

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Sun, Ling, Yazhen Wang, Meixiang Yue, Xialiang Ding, Xiangyang Yu, Jing Ge, Wenjing Sun e Lixiao Song. "Rapid Screening of High-Yield Gellan Gum Mutants of Sphingomonas paucimobilis ATCC 31461 by Combining Atmospheric and Room Temperature Plasma Mutation with Near-Infrared Spectroscopy Monitoring". Foods 11, n.º 24 (16 de dezembro de 2022): 4078. http://dx.doi.org/10.3390/foods11244078.

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In this study, an efficient mutagenesis and rapid screening method of high-yield gellan gum mutant by atmospheric and room temperature plasma (ARTP) treatment combined with Near-Infrared Spectroscopy (NIRS) was proposed. A NIRS model for the on-line detection of gellan gum yield was constructed by joint interval partial least squares (siPLS) regression on the basis of chemical determination and NIRS acquisition of gellan gum yield. Five genetically stable mutant strains were screened using the on-line NIRS detection of gellan gum yield in the fermentation from approximately 600 mutant strains induced by ARTP. Remarkably, compared with the original strain, the gellan gum yield of mutant strain 519 was 9.427 g/L (increased by 133.5%) under the optimal fermentation conditions, which was determined by single-factor and response surface optimization. Therefore, the method of ARTP mutation combined with the NIRS model can be used to screen high-yield mutant strains of gellan gum and other high-yield polysaccharide strains.

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Wang, Xia, Ping Xu, Yong Yuan, Changlong Liu, Dezhong Zhang, Zhengting Yang, Chunyu Yang e Cuiqing Ma. "Modeling for Gellan Gum Production by Sphingomonas paucimobilis ATCC 31461 in a Simplified Medium". Applied and Environmental Microbiology 72, n.º 5 (maio de 2006): 3367–74. http://dx.doi.org/10.1128/aem.72.5.3367-3374.2006.

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ABSTRACT Gellan gum production was carried out by Sphingomonas paucimobilis ATCC 31461 in a simplified medium with a short incubation time, and a kinetic model for understanding, controlling, and optimizing the fermentation process was proposed. The results revealed that glucose was the best carbon source and that the optimal concentration was 30 g liter−1. As for the fermenting parameters, considerably large amounts of gellan gum were yielded by an 8-h-old culture and a 4% inoculum at 200 rpm on a rotary shaker. Under the optimized conditions, the maximum level of gellan gum (14.75 g liter−1) and the highest conversion efficiency (49.17%) were obtained in a 30-liter fermentor in batch fermentation. Logistic and Luedeking-Piret models were confirmed to provide a good description of gellan gum fermentation, which gave some support for the study of gellan gum fermentation kinetics. Additionally, this study is the first demonstration that gellan gum production is largely growth associated by analysis of kinetics in its batch fermentation process. Based on model prediction, higher gellan gum production (17.71 g liter−1) and higher conversion efficiency (57.12%) were obtained in fed-batch fermentation at the same total glucose concentration (30 g liter−1).

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Hara, Shintaro, Yasuyuki Hashidoko, Roman V. Desyatkin, Ryusuke Hatano e Satoshi Tahara. "High Rate of N2 Fixation by East Siberian Cryophilic Soil Bacteria as Determined by Measuring Acetylene Reduction in Nitrogen-Poor Medium Solidified with Gellan Gum". Applied and Environmental Microbiology 75, n.º 9 (13 de março de 2009): 2811–19. http://dx.doi.org/10.1128/aem.02660-08.

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ABSTRACT For evaluating N2 fixation of diazotrophic bacteria, nitrogen-poor liquid media supplemented with at least 0.5% sugar and 0.2% agar are widely used for acetylene reduction assays. In such a soft gel medium, however, many N2-fixing soil bacteria generally show only trace acetylene reduction activity. Here, we report that use of a N2 fixation medium solidified with gellan gum instead of agar promoted growth of some gellan-preferring soil bacteria. In a soft gel medium solidified with 0.3% gellan gum under appropriate culture conditions, bacterial microbiota from boreal forest bed soils and some free-living N2-fixing soil bacteria isolated from the microbiota exhibited 10- to 200-fold-higher acetylene reduction than those cultured in 0.2% agar medium. To determine the N2 fixation-activating mechanism of gellan gum medium, qualitative differences in the colony-forming bacterial components from tested soil microbiota were investigated in plate cultures solidified with either agar or gellan gum for use with modified Winogradsky's medium. On 1.5% agar plates, apparently cryophilic bacterial microbiota showed strictly distinguishable microbiota according to the depth of soil in samples from an eastern Siberian Taiga forest bed. Some pure cultures of proteobacteria, such as Pseudomonas fluorescens and Burkholderia xenovorans, showed remarkable acetylene reduction. On plates solidified with 1.0% gellan gum, some soil bacteria, including Luteibacter sp., Janthinobacterium sp., Paenibacillus sp., and Arthrobacter sp., uniquely grew that had not grown in the presence of the same inoculants on agar plates. In contrast, Pseudomonas spp. and Burkholderia spp. were apparent only as minor colonies on the gellan gum plates. Moreover, only gellan gum plates allowed some bacteria, particularly those isolated from the shallow organic soil layer, to actively swarm. In consequence, gellan gum is a useful gel matrix to bring out growth potential capabilities of many soil diazotrophs and their consortia in communities of soil bacteria.

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Sworn, G., G. R. Sanderson e W. Gibson. "Gellan gum fluid gels". Food Hydrocolloids 9, n.º 4 (dezembro de 1995): 265–71. http://dx.doi.org/10.1016/s0268-005x(09)80257-9.

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Grasdalen, Hans, e Olav Smidsrød. "Gelation of gellan gum". Carbohydrate Polymers 7, n.º 5 (janeiro de 1987): 371–93. http://dx.doi.org/10.1016/0144-8617(87)90004-x.

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Hilal, Adonis, Anna Florowska, Tomasz Florowski e Małgorzata Wroniak. "A Comparative Evaluation of the Structural and Biomechanical Properties of Food-Grade Biopolymers as Potential Hydrogel Building Blocks". Biomedicines 10, n.º 9 (28 de agosto de 2022): 2106. http://dx.doi.org/10.3390/biomedicines10092106.

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The aim of this study was to conduct a comparative assessment of the structural and biomechanical properties of eight selected food-grade biopolymers (pea protein, wheat protein, gellan gum, konjac gum, inulin, maltodextrin, psyllium, and tara gum) as potential hydrogel building blocks. The prepared samples were investigated in terms of the volumetric gelling index, microrheological parameters, physical stability, and color parameters. Pea protein, gellan gum, konjac gum, and psyllium samples had high VGI values (100%), low solid–liquid balance (SLB < 0.5), and high macroscopic viscosity index (MVI) values (53.50, 59.98, 81.58, and 45.62 nm−2, respectively) in comparison with the samples prepared using wheat protein, maltodextrin, and tara gum (SLB > 0.5, MVI: 13.58, 0.04, and 0.25 nm−2, respectively). Inulin had the highest elasticity index value (31.05 nm−2) and MVI value (590.17 nm−2). The instability index was the lowest in the case of pea protein, gellan gum, konjac gum, and inulin (below 0.02). The color parameters and whiteness index (WI) of each biopolymer differed significantly from one another. Based on the obtained results, pea protein, gellan gum, konjac gum, and psyllium hydrogels had similar structural and biomechanical properties, while inulin hydrogel had the most diverse properties. Wheat protein, maltodextrin, and tara gum did not form a gel structure.

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Yamada, Masanori, e Yoshihiro Kametani. "Preparation of Gellan Gum-Inorganic Composite Film and Its Metal Ion Accumulation Property". Journal of Composites Science 6, n.º 2 (25 de janeiro de 2022): 42. http://dx.doi.org/10.3390/jcs6020042.

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Gellan gum is one of the water-soluble anionic polysaccharides produced by the bacteria Sphingomonas elodea. In this study, we prepared gellan gum-inorganic composite films by mixing the gellan gum and a silane coupling reagent—3-glycidoxypropyltrimethoxysilane (GPTMS). These gellan gum-GPTMS composite films were stable in an aqueous solution and showed a thermal stability. In addition, these composite films indicated a mechanical strength by the formation of the three-dimensional network of siloxane. We demonstrated the accumulation of metal ions from a metal ion-containing aqueous solution by the composite film. As a result, although the composite film indicated the accumulation of heavy and rare-earth metal ions, the light metal ions, such as Mg(II) and Al(III) ions, did not interact with the composite material. Therefore, the accumulative mechanism of metal ions using a composite film was evaluated by IR measurements. As a consequence, although the accumulation of heavy and rare-earth metal ions occurred at both the −COO− group and the −OH group in the gellan gum, the accumulation of light metal ions occurred only at the −OH group.

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Teses / dissertações sobre o assunto "Gellan gum"

McGovern-Traa, Caroline. "Studies on gellan gum". Thesis, University of Edinburgh, 1994. http://hdl.handle.net/1842/15337.

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The composition of gellan gum elaborated by wild type Sphingomonas paucimobilis was studied. Gas chromatographic methods of analysis were compared. Analysis of neutral sugars was carried out by Saemen hydrolysis and Stones method. Stones method was preferred due to its simplicity and the production of comparable results to those obtained following Saemen hydrolysis. The neutral sugars of gellan gum were analysed by GC/MS following preparation of per-methylated alditol acetates (PMAAs). Two methods were used for making alditol acetates, the Hakamori and sodium hydroxide (NaOH) methods. Although the NaOH method was simpler and faster to carry out, the results were not representative of the true composition of gellan gum. The Hakamori method revealed the presence of 33%, 1,4 rha, 30% 1,3 glc and 31% 1,4 glc in agreement with the sugar compositions of O'Neill et al. (1983) and Jansson et al. (1983) who elucidated the structure of gellan gum simultaneously. To determine the glucuronic acid content of gellan gum, samples were carboxy-reduced prior to analysis. Two methods were compared, the lithium aluminium deuteride and tetrahydrofuran (THF) methods. The THF method revealed the presence of 24%, 1, 4 rha, 24% 1,3 glc 26% 1,4 glc and 25% 1,4, 6 glc (corresponding to glcA). Physiological studies were carried out with twenty mutant strains of S. paucimobilis in batch culture. The chemical composition, viscosity, gelation and rheological properties of EPS produced from many of these strains were further investigated. Some of the strains elaborated polysaccharide, named fine precipitate, which differed chemically from gellan gum. Rheological measurements were carried out on several EPS samples using a mechanical rheometer. Large differences in gel strength were detected.

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Gothard, Michelle Gina Elizabeth. "Functional properties of gellan gum". Thesis, Cranfield University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426116.

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Cassanelli, Mattia. "Drying and rehydration of gellan gum gels". Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8810/.

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This research shows, for the first time, the freeze dried low acyl (LA) gellan gum, high acyl (HA) and HA:LA mixture gel structures and their properties upon rehydration. The water interaction with the gel structure is affected by the presence of acyl groups along the HA gellan gum polymer chain. The rehydration rate was shown to be lower for HA gellan gum and was not dependent on the polymer concentration. In the second instance, the effect of the gel pH on the freeze- and oven-dried structure is studied as well as the water re-absorption extent and rate. In this part, two drying methods, freeze- and oven-drying, were performed. Finally, a comparison of the three drying processes (freeze-, oven- and supercritical-fluid drying) is reported, proposing the effect on the molecular structure by investigation of the disordered chain domains of the gel network. As supercritical-fluid drying requires a pre-treatment in alcohol, its effect on the gellan gum network was investigated. It is shown how alcohols change the gellan gum configuration, leading to a considerable variation in gel texture. A novel supercritical-fluid batch rig is also proposed, characterised by high process flexibility and reduced set-up and energetic costs, particularly suitable for small/laboratory-scale use.

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Dhameri, Sulaiman Ali A. "Rheological Properties and Decomposition Rates of Gellan Gum". University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1562780919692096.

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Yang, Li. "Physicochemical properties of biodegradable/edible films made with gellan gum". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0026/MQ31662.pdf.

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Tsiami, Amalia A. "Physiochemical properties of Gellan gum in gel and solution state". Thesis, University of East Anglia, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358455.

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Giavasis, Ioannis. "Physiological studies on the production of gellan gum by Sphingomonas paucimobilis". Thesis, University of Strathclyde, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273429.

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Baawad, Abdullah. "Release of Low Acyl Gellan Gum in a Controlled Release System". University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1544823979777171.

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Mahdi, Mohammed Hamzah. "Development of gellan gum fluid gel as modified release drug delivery systems". Thesis, University of Huddersfield, 2016. http://eprints.hud.ac.uk/id/eprint/30293/.

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Gelation of polysaccharides under shear conditions results in the formation of a weak gel which is able to resist elastic mechanical deformation at small strains but will flow if subjected to higher strains. The resulting material, described in the literature as a fluid gel or a sheared gel, consists of gelled microparticles which can be formulated to collectively act in bulk, as pourable viscoelastic fluids whilst retaining true gel characteristics at the micro/nano level. The tuneable behaviour of these fluid gel systems makes them potentially useful in pharmaceutical applications. Fluid gels prepared from gellan gum are particularly attractive, due to its sensitivity to physiological fluids, unique rheological and physical properties, and current regulatory approval for use as a food additive and pharmaceutical excipient. Therefore, the aim of the present study was to investigate gellan gum fluid gels as a new modified release drug delivery platform. The formation and production of fluid gels using low acyl (LA) gellan, high acyl (HA) gellan and LA HA gellan blends was investigated and applied in three different dosage forms; a modified release oral liquid, a mucoadhesive nasal spray and a topical formulation. A modified release oral liquid was designed using a fluid gel prepared from LA gellan gum. It was demonstrated that 0.75 % w/w LA gellan gum fluid gel, containing ibuprofen as the drug, could be formulated to have a similar viscosity profile as a marketed oral ibuprofen liquid. Furthermore, due to the acid insolubility of gels prepared from LA gellan, no ibuprofen was released in stimulated gastric fluid. Subsequent release at pH 7.4 however, was affected by the duration of exposure and strength of the acidic pH used and a linear relationship between onset of release and the preceding duration of acid exposure was observed. Delayed release was a result of increasing gel stiffness, a consequence of the acidity of the initial release media and exposure time. A much faster release rate was measured when exposure time in acid was 10 min compared with 60 min. This study highlights the potential to design fluid gels that are tuned to have a specified stiffness at a particular pH and exposure time allowing the intelligent design oral liquids with specific modified release behaviour. The second part of this study was to prepare mucoadhesive nasal drug delivery systems to enhance the retention of the nasal spray dosage form in the nasal cavity. Several groups have investigated using LA gellan solution as a drug delivery vehicle but only limited research however, has been performed on HA gellan for this purpose, despite its properties being more conducive to mucoadhesion. HA gellan (even with low concentration 0.25 % w/w) produces highly elastic gels below 60 °C which make it difficult to spray using a mechanical spray device. To address this problem, fluid gels were prepared as these systems can behave as sprayable viscoelastic fluids. In this study the rheological behaviour was investigated and the mucoadhesion behaviour of fluid gels prepared from the two different types of gellan (HA and LA) and fluid gels prepared from a blend of LA HA gellan. The results demonstrated that by preparing fluid gels from a blend of LA HA gellan, the rheological properties were sufficient to spray through a standard nasal spray device. Moreover, the fluid gels significantly enhanced both HA and LA gellan mucoadhesion properties. In the final part of this thesis the topical application of gellan fluid gels was explored. A range of gellan fluid gel formulations were prepared containing diclofenac sodium for topical application. The rheological results showed that it was possible to produce a topical formulation with a viscosity and the mechanical strength similar to that of the commercially available Voltaren® gel using 1 % w/w of a 50:50 LA HA gellan blend. The permeation results highlighted that the penetration of diclofenac through procaine tissue is significantly increased by increasing gellan concentration and decreasing sodium ion concentration in the formulation.

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Picone, Carolina Siqueira Franco 1983. "Formação de nanopartículas por associação de biopolímeros e surfactantes = Formation of nanoparticles by biopolymer - surfactant association". [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/254194.

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Orientador: Rosiane Lopes da Cunha
Texto em português e inglês
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-20T12:57:32Z (GMT). No. of bitstreams: 1 Picone_CarolinaSiqueiraFranco_D.pdf: 4074904 bytes, checksum: 1a2779daa118fabb35ba241a8f6bf16f (MD5) Previous issue date: 2012
Resumo: As nano partículas possuem grande potencial para a liberação controlada de bioativos, porém ainda são pouco exploradas na área de alimentos. Neste trabalho foi estudada a formação de nanopartículas a partir da autoagregação de surfactantes, associação surfactante-polissacarídeo e complexação eletrostática entre diferentes polissacarídeos, no caso, quitosana e gelana. A compreensão das interações moleculares responsáveis pela formação das partículas e o conhecimento das variáveis que afetam sua formação permitem predizer e controlar suas propriedades. Tais interações dependem fortemente das características de cada macromolécula, como flexibilidade, estado conformacional e densidade de cargas que são diretamente afetadas pelas condições físico-químicas do meio como pH, força iônica e temperatura. Por isso, este trabalho foi dividido em três etapas. (I) Inicialmente foi avaliado o comportamento em solução dos polissacarídeos utilizados posteriormente para a formação de complexos. Os efeitos do pH e da temperatura nas características reológicas e no estado conformacional de soluções puras de gelana e quitosana foram estudados. A agregação da gelana foi mais sensível às alterações do meio que a quitosana. (II) Na segunda etapa, nanopartículas foram formadas por autoassociação de polissorbatos na presença de quitosana. A influência do comprimento da cauda hidrofóbica do surfactante e do pH do meio nas propriedades das partículas foi estudada por espalhamento de luz, reologia, condutivimetria e microscopia de luz polarizada. O tamanho e estrutura das partículas formadas pelo surfactante de menor cadeia hidrofóbica foram mais favoráveis à associação com a quitosana. O pH do meio (3,0 ou 6,7) não influenciou de maneira significativa as características das partículas. O efeito da concentração de quitosana na estrutura e tamanho de partículas foi analisado. Maiores concentrações levaram a viscosidades mais elevadas, impedindo a agregação das micelas e formando partículas menores. (III) No terceiro estudo, nanopartículas foram obtidas pela complexação eletrostática de gelana e quitosana. Os efeitos da razão de concentração de cada polissacarídeo, do tempo de estocagem a 25 °C e da presença de um surfactante nãoiônico (polissorbato) no tamanho, carga e quantidade de partículas formadas foram avaliados. Devido à menor densidade de carga e flexibilidade da gelana, maior quantidade deste polissacarídeo foi necessária para obtenção de partículas neutras. De forma geral, as partículas apresentaram aumento de tamanho ao longo das primeiras 100 horas após o preparo e não foram observadas mudanças significativas das propriedades das partículas devido à adição de surfactante. O método de preparo das amostras também foi estudado. Partículas preparadas pela mistura das soluções de polissacarídeos em dois passos foram consideravelmente maiores que as preparadas pela mistura em uma única etapa. Este trabalho confirmou a possibilidade de formação de nanopartículas promissoras para a encapsulação de bioativos em alimentos a partir da associação de biopolímeros e surfactantes, cujas propriedades poderiam ser moduladas em função da composição e condições de processo
Abstract: Nanoparticles are promising vehicles for bioactive delivery, but their potential has not been fully explored by the food industry. This work studied the formation of nanoparticles by self-assembly of surfactants, polysaccharide-surfactant association, and electrostatic complexes formed by different polysaccharides, especially chitosan and gellan gum. The knowledge of molecular interactions and the variables that affect particle formation allows predicting and controlling the properties of nanoparticles. These interactions depend on the characteristics of each macromolecule such as conformation, charge density and flexibility, which are affected by the physicol-chemical properties of the solution, such as pH, ionic strength and temperature. This work was divided in three parts: (I) Firstly it was studied the behaviour of each polysaccharide alone. The influence of the pH and temperature on the rheological properties and structural conformation of the pure gellan and chitosan samples was determined. Gellan aggregation was more strongly affected by such variables than chitosan. (II) In the second part, nanoparticles were obtained by polysorbate-chitosan association. The effect of the length of surfactant tail and the solution pH on the particle properties was studied by dynamic light scattering, rheological and conductivity measurements and polarizing microscopy. The size and structure of nanoparticles composed by the shorter surfactant were more appropriated to chitosan assembly. The pH (6.7 or 3.0) did not affect significantly the particle properties. The effects of chitosan concentration on particle structure and size were studied. Greater chitosan concentration led to smaller particles due to the increase in viscosity values which prevented micelles aggregation. (III) In the third study nanoparticles were produced by electrostatic complexation of chitosan and gellan gum. Particle size, charge density, stability and complexes number were evaluated as a function of polysaccharide concentration, chitosan:gellan ratio and the presence of a non-ionic surfactant. Due to the stiffness and low charge density of gellan gum, a greater amount of such polysaccharide was necessary to obtain neutral particles. Overall particles showed an increase in size during 100 hours of storage at 25 °C, but no significant changes on particle properties were observed due to surfactant addition. The methodology of particle preparation was also evaluated. Particles prepared by 2 mixing steps were markedly larger than those prepared by mixing polysaccharides in a single step (all together). This work showed that it is possible to produce nanoparticles with promising application on bioactive delivery by biopolymer-surfactant association, since their properties could be modulated as a function of composition and process conditions
Doutorado
Engenharia de Alimentos
Doutor em Engenharia de Alimentos

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Livros sobre o assunto "Gellan gum"

Nishinari, K., ed. Physical Chemistry and Industrial Application of Gellan Gum. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/3-540-48349-7.

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Tsiami, Amalia A. Physiochemical properties of gellan gum in gel and solution state. Norwich: University of East Anglia, 1994.

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Ce lue gui hua jia : Zhu Geliang da zhuang. Taibei Shi: Yuan liu chu ban shi ye gu fen you xian gong si, 1992.

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Indonesia) Festival Legu Gam Moloku Kie Raha (2011 Ternate. Geliat Legu gam Moloku kie raha: Pesona kie raha, pesona Nusantara. Ternate Tengah]: Dewan Pakar Kesultanan Ternate, 2011.

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Bergmann, Jörg R., e Christian Meyer, eds. Ethnomethodologie reloaded. Bielefeld, Germany: transcript Verlag, 2021. http://dx.doi.org/10.14361/9783839454381.

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Harold Garfinkels 1967 erschienene »Studies in Ethnomethodology« gelten als Gründungsdokument der Ethnomethodologie und haben längst den Status eines soziologischen Klassikers. Doch so bekannt dieses Buch ist, so wenig wurde es tatsächlich gelesen. Angesichts radikaler Veränderungen der Lebenswelt unterziehen die Beiträger*innen des Bandes die »Studies« gut 50 Jahre nach ihrer Ersterscheinung einer Relektüre. Sie decken bisher verborgene Bezüge auf, rekapitulieren methodologische und empirische Anschlüsse an Garfinkel, diskutieren Parallelen und Differenzen zu anderen soziologischen und kulturwissenschaftlichen Forschungsprogrammen und demonstrieren das kritische Potenzial der Ethnomethodologie.

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(Firm), NutraSweet Kelco, e Monsanto, eds. Alginates, xanthan gum & gellan gum seminar. Tadworth, Surrey: NutraSweet Kelco and Monsanto, 1998.

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Nayak, Amit Kumar, e Saquib Hasnain. Gellan Gum As a Biomedical Polymer. Elsevier Science & Technology Books, 2022.

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Gellan Gum As a Biomedical Polymer. Elsevier Science & Technology, 2023.

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Nishinari, K. Physical Chemistry and Industrial Application of Gellan Gum. Springer, 2013.

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Nishinari, K. Physical Chemistry and Industrial Application of Gellan Gum. Springer London, Limited, 2003.

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Capítulos de livros sobre o assunto "Gellan gum"

Nussinovitch, A. "Gellan gum". In Hydrocolloid Applications, 63–82. Boston, MA: Springer US, 1997. http://dx.doi.org/10.1007/978-1-4615-6385-3_4.

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Gibson, W. "Gellan gum". In Thickening and Gelling Agents for Food, 227–49. Boston, MA: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4615-3552-2_10.

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Gibson, W., e G. R. Sanderson. "Gellan gum". In Thickening and Gelling Agents for Food, 119–43. Boston, MA: Springer US, 1997. http://dx.doi.org/10.1007/978-1-4615-2197-6_6.

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Sanderson, G. R. "Gellan Gum". In Food Gels, 201–32. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0755-3_6.

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Bährle-Rapp, Marina. "Gellan Gum". In Springer Lexikon Kosmetik und Körperpflege, 219. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-71095-0_4207.

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Monferrer, Albert, Claudia Cortés, Núria Cubero e Laura Gómez. "E-418 Gellan Gum". In Hydrocolloids in food product development, 105–11. Boca Raton, FL : CRC Press, [2020]: CRC Press, 2020. http://dx.doi.org/10.1201/9781003019862-12.

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Sanderson, George R., e David Ortega. "Alginates and Gellan Gum: Complementary Gelling Agents". In Food Hydrocolloids, 83–89. Boston, MA: Springer US, 1994. http://dx.doi.org/10.1007/978-1-4615-2486-1_8.

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Panda, Pritish Kumar, Amit Verma, Shivani Saraf, Ankita Tiwari e Sanjay K. Jain. "Ionically Gelled Gellan Gum in Drug Delivery". In Ionically Gelled Biopolysaccharide Based Systems in Drug Delivery, 55–69. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-2271-7_3.

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Nagpal, Shakti, Sunil Kumar Dubey, Vamshi Krishna Rapalli e Gautam Singhvi. "Pharmaceutical Applications of Gellan Gum". In Natural Polymers for Pharmaceutical Applications, 87–109. Includes bibliographical references and indexes.: Apple Academic Press, 2019. http://dx.doi.org/10.1201/9780429328299-4.

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Vendrusculo, Claire T., José L. Pereira e Adilma R. P. Scamparini. "Gellan Gum: Production And Properties". In Food Hydrocolloids, 91–95. Boston, MA: Springer US, 1994. http://dx.doi.org/10.1007/978-1-4615-2486-1_9.

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Trabalhos de conferências sobre o assunto "Gellan gum"

Ya´n˜ez-Ferna´ndez, J., J. A. Salazar-Montoya e E. G. Ramos-Rami´rez. "Effect of Mesquite Seed Gum on the Rheological Properties of Mixtures With Arabic and Gellan Gums". In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-32195.

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The mesquite seed gum (Prosopis sp.) represents an alternative application in the food industry, due to its structural likeness with other galactomannans used at the moment. The information about the properties of mesquite seed gum is scarce, for this is important to known the rheological properties of this biopolymer and its interactions with other polymers for seeing future applications. The aim of this work was study the rheological behavior of mesquite seed gum and their effects in arabic and gellan gum mixtures. They were prepared aqueous dispersions according to a Simplex-Centroid design, being obtained gum combinations of total concentration of 1% from mesquite-arabic, mesquite-gellan, arabic-gellan and mesquite-arabic-gellan, the pH from the dispersions were adjusted to 4, 5 and 6. The mixtures as well as the individual biopolymers were dispersed to ambient temperature, and later heated during 20 minutes at 90 °C and cooling at 25 °C. The rheological studies were made using an Haake RV2 viscometer. The statistical analysis showed differences (α = 0.05) among the rheologic value for mixtures at different pH. The mixtures showed a non-Newtonian behavior, type pseudoplastic flow (shear thinning) and showed high viscosities to low shears rates (100 s−l) in all the cases. The tendency of mixtures with two or three components showed an antagonistic effect in the viscosity. Particularly the mesquite seed gum suffers an antagonistic effect in the viscosity when it was mixed with the arabic and gellan gums, being observed decreases from a 8 until 45%, below the control.

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Yu, Ilhan, Roland Chen e Samantha Grindrod. "Fabrication of Gellan Gum Tubular Structure Using Coaxial Needles: A Study on Wall Thickness and Encapsulation". In ASME 2018 13th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/msec2018-6614.

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Tubular structures of hydrogel are used in a variety of applications such as 3D cell culturing for delivery of nutrient supplies. The wall thickness of the tube determines the speed of diffusion or delivery rate. In this study, we aimed to fabricate tubular structures with varying of wall thicknesses using a thermal-crosslinking hydrogel, gellan gum, with the coaxial needle approach. The wall thickness is controlled by changing the flow rate ratio between the inner (phosphate-buffered saline) and outer needles (gellan gum). A simulation model was developed to estimate the proper extrusion speed to allow the gellan gum to be extruded around its glass transition temperature. While keeping the extrusion rate of gellan gum fixed, different PBS extrusion rates were tested to investigate the printability to form continuous tubular structures, range of printable wall thickness, and possibility to form tubes with closed ends to encapsulate fluid or drug inside the tube. The ranges of printable wall thickness with two pairs of coaxial needle were identified. It was found that at about 200% of the baseline PBS extrusion speed, a maximum of 20% difference in wall thickness can be achieved, while a close end can still be formed.

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Torres, Francisco R., Pedro H. L. Sanches, Hernane S. Barud e José Maurício A. Caiut. "Biocomposites of Eu3+-doped gellan gum and nanocellulose for 3D printing". In Latin America Optics and Photonics Conference. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/laop.2022.w1a.2.

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Development of biocomposites of Eu3+-doped gellan gum reinforced with cellulose nanocrystals, using the lanthanide ion as a probe to study the structure and to obtain a luminescent compound with 3D printing properties.

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Ferris, C. J., e M. in het Panhuis. "Diffusion of vitamin B12 in gellan gum-carbon nanotube hydrogels". In 2010 International Conference on Nanoscience and Nanotechnology (ICONN). IEEE, 2010. http://dx.doi.org/10.1109/iconn.2010.6045180.

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Modrogan, Cristina. "REMOVAL OF MANGANESE FROM GROUNDWATER BY ADSORPTION ON GELLAN GUM/Fe3O4 COMPOSITE". In 18th International Multidisciplinary Scientific GeoConference SGEM2018. Stef92 Technology, 2018. http://dx.doi.org/10.5593/sgem2018/5.1/s20.091.

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Reichel, Eric, Christopher M. Salinas, Clara Curiel-Lewandrowski e Russell S. Witte. "Transparent Gellan Gum as an Efficient Coupling Media For Photoacoustic Imaging Applications". In 2022 IEEE International Ultrasonics Symposium (IUS). IEEE, 2022. http://dx.doi.org/10.1109/ius54386.2022.9958558.

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K., Mithra, Santripti Khandai e Sidhartha S. Jena. "Effect of sodium dodecyl sulfate surfactant on rheological properties of gellan gum hydrogels". In DAE SOLID STATE PHYSICS SYMPOSIUM 2016. Author(s), 2017. http://dx.doi.org/10.1063/1.4980230.

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Loureiro, Jorge, Sonia P. Miguel, Victor P. Galvan-Chacon, David Patrocinio, Francisco M. Sanchez-Margallo, J. Blas Pagador, Maximiano P. Ribeiro e Paula Coutinho. "Swelling Analysis of Thermal and Chemical Crosslinked Konjac Glucomannan/Gellan Gum Cardiac Patch". In 2021 International Conference on e-Health and Bioengineering (EHB). IEEE, 2021. http://dx.doi.org/10.1109/ehb52898.2021.9657686.

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Cortela, G., K. M. Lima, L. E. Maggi, C. Negreira e W. C. A. Pereira. "Evaluation of acoustic and thermal properties of gellan-gum phantom to mimic biological tissue". In 2015 Pan American Health Care Exchanges (PAHCE). IEEE, 2015. http://dx.doi.org/10.1109/pahce.2015.7173326.

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Muktar, Muhammad Zulhelmi, Laili bt Che Rose e Khairul Anuar Mat Amin. "Formulation and optimization of virgin coconut oil with Tween-80 incorporated in gellan gum hydrogel". In 3RD ELECTRONIC AND GREEN MATERIALS INTERNATIONAL CONFERENCE 2017 (EGM 2017). Author(s), 2017. http://dx.doi.org/10.1063/1.5002238.

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Relatórios de organizações sobre o assunto "Gellan gum"

Kuhnt, Matthias, Tilman Reitz e Patrick Wöhrle. Arbeiten unter dem Wissenschaftszeitvertragsgesetz : Eine Evaluation von Befristungsrecht und -realität an deutschen Universitäten. Technische Universität Dresden, 2022. http://dx.doi.org/10.25368/2022.132.

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Wissenschaftlich Beschäftigte ohne Professur sind vielerorts nicht gut gestellt. In Deutschland kommen zwei Besonderheiten hinzu: Der Anteil befristet beschäftigter Wissenschaftler*innen liegt hier deutlich höher als in anderen Hochschulsystemen, und ihre Stellung wird seit dem Jahr 2007 durch ein eigenes Sonderbefristungsrecht festgeschrieben – das Wissenschaftszeitvertragsgesetz. Das Gesetz wurde nach seiner Einführung evaluiert und u. a. angesichts der Ergebnisse 2016 novelliert; eine weitere Evaluierung ist gesetzlich vorgesehen und für dieses Jahr angekündigt. Die Debatte zur Lage befristet beschäftigten wissenschaftlichen Personals, besonders im sogenannten Nachwuchs, geht jedoch so weit über die amtlich beauftragten Evaluationen hinaus, dass es nötig scheint, das Gesetz unabhängig von den Fragestellungen des zuständigen Ministeriums zu evaluieren. Diese Arbeit legen wir hier vor. In unserer Studie werden Kernargumente zum WissZeitVG und zur in ihm kodifizierten Praxis mit einer detaillierten Befragung der Betroffenen genauer nachvollzogen und überprüfbar gemacht. In einer breit angelegten Online-Befragung haben wir wissenschaftliche Beschäftigte an 23 Universitäten erreicht; 4620 von ihnen haben den Fragebogen auswertbar ausgefüllt. Unsere Analyse zielt auf vier grundlegende Aspekte, die das Sonderbefristungsrecht in der Wissenschaft insgesamt zu beurteilen ermöglichen: 1. Welche Beschäftigungslagen, Qualifikations- und Karriereverläufe werden durch das WissZeitVG typischerweise hergestellt oder unterstützt? 2. Wie wirken sich diese Bedingungen auf Arbeits- und Lebensqualität der Beschäftigten aus? 3. Welche wissenschaftlichen (und nichtwissenschaftlichen) Tätigkeiten und Haltungen werden durch das WissZeitVG befördert? 4. Wie beurteilen die Betroffenen den gesetzlichen Rahmen ihrer Tätigkeit? Mit dieser relativ umfassenden Perspektive heben wir uns von Studien ab, die spezifischer untersucht haben, inwiefern das WissZeitVG Befristungen in der Wissenschaft praktikabel macht und inwieweit seine Novellierung die üblichen Vertragslaufzeiten verlängert hat. Stattdessen ermöglicht unsere Analyse die Grundsatzfrage zu stellen, ob ein Sonderbefristungsrecht in der Wissenschaft überhaupt zu rechtfertigen ist. Folgende Ergebnisse sind besonders hervorzuheben: 1. Unsere Studie bestätigt und vertieft den bekannten Befund, dass das WissZeitVG für das nichtprofessorale wissenschaftliche Personal atypische Beschäftigung zur Norm macht. Sie lässt sich bei weitem nicht nur in den verbreiteten, bei uns zumindest umrisshaft erfassten außertariflichen Arbeitsverhältnissen feststellen. Unter den Befragten herrschen befristete Arbeitsverträge vor (mit 82 %, ähnlich wie in der amtlichen Statistik), und die mittleren Vertragslaufzeiten sind relativ kurz – 23 Monate, mit einem Median von 17 Monaten. Laufzeiten von zwölf Monaten und weniger bilden weiterhin keine Seltenheit. Kettenverträge müssen sogar als Normalfall gelten; im Lauf der vom WissZeitVG gewährten Zwölfjahresfrist sammeln die Befragten durchschnittlich acht Verträge an, bereits nach drei bis sechs Jahren sind es durchschnittlich vier Verträge, oft an derselben Hochschule. Hinzu kommt ein hoher Anteil von Teilzeit-Arbeitsverhältnissen (37 %), die in mindestens der Hälfte der Fälle nicht auf einem Teilzeitwunsch der Beschäftigten beruhen. Beschäftigte auf diesen Stellen arbeiten auch besonders viel mehr als vertraglich vereinbart (im Durchschnitt 13 Stunden pro Woche); bei allen befragten Gruppen stellt Mehrarbeit die Regel dar. 2. Trotz der vielen Arbeit ist festzustellen, dass die Befristung den Qualifikationserwerb oft nicht befördert, sondern erschwert. Ein wichtiger Faktor sind die Vertragsdauern. Sie liegen bei Promovierenden zumeist weit unter der durchschnittlichen Gesamtdauer einer Promotion, bei 39 % dieser Gruppe sogar bei zwei Jahren und weniger. Fast die Hälfte der Befragten, deren Qualifikationsziel ein formaler Abschluss ist, berichtet, dass die Vertragslaufzeit für ihn nicht ausreichen wird. Unter den offiziell zur Habilitation Eingestellten ist dies sogar bei mehr als der Hälfte der Fall, und 23 % von ihnen berichten, faktisch keine Habilitation anzustreben. Der Befund, dass die steil gestiegene Anzahl von Qualifizierungsbeschäftigungen fast keinen Zuwachs wirklicher Qualifikationen hervorbringt (vgl. Gassmann 2020, 44 – 46), lässt sich damit deutlich besser erklären. 3. Sachlich hängen die Defizite faktischer Qualifikationstätigkeit auch damit zusammen, dass andere, teilweise wissenschaftsfremde Tätigkeiten großen Raum einnehmen. Bei den häufig ausgeübten Arbeiten folgt auf Forschung und Lehre unmittelbar die Angabe ›Verwaltung‹ (während die ›akademische Selbstverwaltung‹ eine geringere Rolle spielt), auch Aufbau und Pflege von Netzwerken, Projektanträge und -berichte sind breit vertreten. Ohne Befristung würden die Befragten die meisten dieser Tätigkeiten in geringerem Umfang ausüben, und viele geben an, dass sie für ihre Vorgesetzen Aufgaben erfüllen, für die ihrer Ansicht nach keine vertragliche Grundlage besteht. Für solche Aufgaben (neben Verwaltung und Organisation etwa technische Dienstleistungen oder Zuarbeit zu Lehre und Publikationen) wenden 15 % der Befragten mit Vorgesetzten bis zu drei Stunden, insgesamt 13 % sogar vier bis zwölf Stunden wöchentlich auf. Die Zeit für Qualifizierung schrumpft damit, und 9 % der Promovierenden und Habilitierenden sowie 17 % mit anderem Qualifizierungsziel gaben an, dass ihre faktische Tätigkeit nichts mit dem offiziellen Ziel zu tun hat. 4. Die umrissene Beschäftigungslage beeinträchtigt die Arbeits- und Lebensqualität des wissenschaftlichen Personals. Die kurzen Vertragslaufzeiten, die schlechten Aussichten auf eine Professur und der ›Druck, sich um Anschlussprojekte zu kümmern‹, werden von den befristet Beschäftigten mehrheitlich als ›störend‹ oder ›sehr störend‹ eingeschätzt; ein großer Teil von ihnen (29 %) empfindet so auch die ›Abhängigkeit von Vorgesetzten‹. Auch beim Personal mit unbefristetem Arbeitsvertrag ist in diesen Punkten Unzufriedenheit verbreitet, die Werte sind hier allerdings jeweils merklich geringer. In der Sicht der allermeisten Befragten lassen sich die Befristungen zudem schlecht mit Freundschaften, Partnerschaft und Kinderbetreuung vereinbaren. Für die Zeit nach der Promotion schreiben ihnen über 90 % einen negativen Einfluss auf das Privatleben zu. Das ist auch handlungsrelevant. Mehr als ein Drittel der Befragten hat bereits einmal aufgrund der Beschäftigungslage einen Kinderwunsch zurückgestellt, bei den Beschäftigten mit Kindern hat eine Mehrheit häufig oder sehr häufig Betreuungsschwierigkeiten, und 19 % berichten, dass während ihrer Elternzeit bereits einmal ein Arbeitsverhältnis ausgelaufen ist. 5. Das WissZeitVG beeinträchtigt darüber hinaus die Qualität wissenschaftlicher Praxis. Das lässt sich nicht allein am berichteten Ausmaß wissenschaftsfremder Tätigkeiten ablesen, sondern auch daran, welchen Faktoren die Befragten Bedeutung für ihr berufliches Fortkommen zumessen: Am häufigsten wurden hier Netzwerke und Kontakte genannt, neben Publikationen spielten auch Konferenzteilnahmen und das Einwerben von Projektgeldern eine sehr wichtige Rolle. Zugleich bedroht die fortgesetzte Unsicherheit und Abhängigkeit den Kern wissenschaftlicher Kommunikation. Auf die Frage, ob sie sich fallweise mit wissenschaftlicher Kritik zurückhalten, um ihre Stellung nicht zu gefährden, antworteten die befristet Beschäftigten zu insgesamt 40 % mit ›teilweise‹, ›häufig‹ oder sogar ›immer‹ – während bei den unbefristet Beschäftigten nur 24 % diese Antworten gaben. Persönliches und wissenschaftliches Fehlverhalten wird unter den bestehenden Bedingungen oft nicht gemeldet (35 % der Befragten haben dies schon einmal unterlassen); hier lässt sich allerdings keine starke Korrelation zur Befristung erkennen. 6. Angesichts dieser Erfahrungen verwundert es nicht, dass die Befragten das WissZeitVG und die durch es ermöglichte Praxis mehrheitlich ablehnen. Oft behauptete positive Effekte befristeter Beschäftigungsverhältnisse werden (besonders für die Zeit nach der Promotion) überwiegend bestritten. Anders als die Kanzler der deutschen Hochschulen sind die Befragten mehrheitlich nicht der Ansicht, dass diese Verhältnisse die ›erforderliche personalpolitische Flexibilität‹ schaffen, die ›Produktivität wissenschaftlichen Arbeitens‹ steigern oder die ›Innovationskraft der Wissenschaft‹ erhöhen. Verbesserungen würden für die meisten Befragten daher deutliche Korrekturen erfordern. Für viele wäre es hilfreich, wenn Qualifikationsziele genauer bestimmt oder Befristungsdauern verlängert würden. Mit besonders großer Mehrheit bejahen sie schließlich zwei grundlegende Änderungen: 76 % wären für eine ›Abschaffung des Sonderbefristungsrechts in der Wissenschaft‹ und 86 % dafür, eine unbefristete Beschäftigung ab der Promotion zur Regel zu machen. Für die Novelle bzw. Ersetzung des WissZeitVG liegen damit klare Kriterien vor.

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Kuhnt, Mathias, Tilman Reitz e Patrick Wöhrle. Arbeiten unter dem Wissenschaftszeitvertragsgesetz : Eine Evaluation von Befristungsrecht und -realität an deutschen Universitäten. Technische Universität Dresden, 2022. http://dx.doi.org/10.25368/2022.366.

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