scholarly journals Analysis of the Heterogeneities of First and Second Order of Cellulose Derivatives: A Complex Challenge

2021 ◽  
Vol 2 (4) ◽  
pp. 843-865
Author(s):  
Petra Mischnick ◽  
Kristin Voiges ◽  
Julia Cuers-Dammann ◽  
Inga Unterieser ◽  
Patrick Sudwischer ◽  
...  
Keyword(s):  
Methyl Cellulose ◽  
Normal Phase ◽  
Second Order ◽  
Cellulose Derivatives ◽  
Cellulose Ethers ◽  
Substituent Distribution ◽  
Analytical Work ◽  
Polysaccharide Derivatives ◽  
Analytical Approaches

The complexity of the substituent distribution in polysaccharide derivatives is discussed and defined. The challenges regarding analytical characterization that results from various interrelated categories of distributions, including molecular weight, chemical composition, and microstructure, are outlined. Due to these convoluted levels of complexity, results should always be interpreted with carefulness. Various analytical approaches which have been applied to starch and cellulose derivatives are recapped, including enzymatic, mass spectrometric, and chromatographic methods. The relation of heterogeneities of first and second order among and along the polysaccharide chains is addressed. Finally, examples of own analytical work on cellulose ethers are presented, including the MS analysis of methyl cellulose (MC) blends and fractionation studies of fully esterified MC, especially its 4-methoxybenzoates by gradient HPLC on normal phase. Preparative fractionation according to the degree of substitution (DS) allows follow-up analysis in order to get more detailed information on the substituent distribution in such sub-fractions.

Out-of-plane static compression and energy absorption of paper hierarchical corrugation sandwich panels

2021 ◽  
pp. 030932472110085
Author(s):  
Huineng Wang ◽  
Yanfeng Guo ◽  
Yungang Fu ◽  
Dan Li
Keyword(s):  
Yield Strength ◽  
Bearing Capacity ◽  
Energy Absorption ◽  
Sandwich Panel ◽  
Second Order ◽  
Compression Rate ◽  
Static Compression ◽  
First Order ◽  
Out Of Plane ◽  
Analytical Approaches

This study introduces the opinion of the corrugation hierarchy to develop the second-order corrugation paperboard, and explore the deformation characteristics, yield strength, and energy absorbing capacity under out-of-plane static evenly compression loading by experimental and analytical approaches. On the basis of the inclined-straight strut elements of corrugation unit and plastic hinge lines, the yield and crushing strengths of corrugation unit were analyzed. This study shows that as the compressive stress increases, the second-order corrugation core layer is firstly crushed, and the first-order corrugation structures gradually compacted until the failure of entire structure. The corrugation type has an obvious influence on the yield strength of the corrugation sandwich panel, and the yield strength of B-flute corrugation sandwich panel is wholly higher than that of the C-flute structure. At the same compression rate, the flute type has a significant impact on energy absorption, and the C-flute second-order corrugation sandwich panel has better bearing capacity than the B-flute structure. The second-order corrugation sandwich panel has a better bearing capacity than the first-order structure. The static compression rate has little effect on the yield strength and deformation mode. However, with the increase of the static compression rate, the corrugation sandwich panel has a better cushioning energy absorption and material utilization rate.

scholarly journals Effect of 1,4-Napthaquinone (NQ) and benzophenone (BPH)on the photodegradation and biodegradation of methyl cellulose film

2010 ◽  
Vol 7 (1) ◽  
pp. 737-744
Author(s):  
Baghdad Science Journal
Keyword(s):  
Molecular Weight ◽  
Film Thickness ◽  
Carbonyl Compounds ◽  
Methyl Cellulose ◽  
Chain Scission ◽  
Cellulose Derivative ◽  
Accelerated Weathering ◽  
Cellulose Derivatives ◽  
Photodegradation Rate ◽  
Aromatic Carbonyl Compounds

The induced photodegradation of methyl cellulose (MC) films in air was investigated in the absence and presence of aromatic carbonyl compounds(photosenssitizers): 1,4-naphthaquinone (NQ) and benzophenone (BPH) by accelerated weathering tester. The addition of (0.01 wt %) of low molecular weight aromatic carbonyl compounds to cellulose derivatives films(25µm in thickness) enhanced the photodegradation of the polymer films.The photodegradation rate was measured by the increase in carbonyl absorbance. Decreases in solution viscosity and reduction of molecular weight were also observed in the irradiated samples. Changes in the number-average chain scission, the degree of deterioration and in the quantum yield of chain scission values are also observed, and it was concluded that branching or cross-linking has occurred for cellulose derivative with NQ and BPH. Findings from all analytical techniques indicated that the 1,4-naphthaquinone (NQ) photosensitizer enhance the photodegradation of methyl cellulose more than benzophenone (BPH). The effect of the photosensitizer concentration, (ranging from 0.01 to 0.1 %), on the rate of photodegradation was also monitored for MC films. The rates are increased with increasing the photosensitizer concentration. The effect of film thickness is also studied at fixed sensitizer concentration (0.05%), and results show that the rate of cellulose derivative photodegradation decreases with increasing film thickness. The rate constants of the photodegradation of the photosensitizers deduced in cellulose derivatives films, [at concentration of (0.1%)by weight and thickness (25µm)]. Biodegradation of irradiated cellulose derivatives films was conclusively established with bacteria type Pseudomonas aeuroginosa Rb-19 isolated from crude oil. The amount of bacteria growth on MC after 30 days was lower, while there was no growth observed in MC with BPH

scholarly journals Risk of malignancies in patients with spondyloarthritis treated with biologics compared with those treated with non-biologics: a systematic review and meta-analysis

2020 ◽  
Vol 12 ◽  
pp. 1759720X2092569
Author(s):  
Yu Heng Kwan ◽  
Ka Keat Lim ◽  
Warren Fong ◽  
Hendra Goh ◽  
Linkai Ng ◽  
...  
Keyword(s):  
Meta Analysis ◽  
Risk Of Bias ◽  
Cochrane Library ◽  
Interleukin 17 ◽  
Randomized Controlled ◽  
Risk Of Malignancy ◽  
Meta Analyses ◽  
Analytical Approaches

Background: The aim of our study was to synthesize evidence on the occurrence of malignancy in spondyloarthritis (SpA), from randomized controlled trials (RCTs) comparing biologics with non-biologics and biologics to each other. Methods: We systematically searched Medline, Cochrane Library, EMBASE, Scopus and ClinicalTrials.gov from inception until 31 October 2018. RCTs with ⩾24-week follow-up were included. We extracted data using standardized forms and assessed the risk of bias using the Cochrane Risk of Bias Tool. We performed pair-wise meta-analyses and network meta-analyses to compare the risk of malignancy for each biologics class and SpA type. We reported the Peto odds ratio (OR) of any malignancy along with 95% confidence intervals (95% CI). Bayesian posterior probabilities comparing risk of malignancy of each biologic class with non-biologics were computed as supplementary measures. Results: Fifty-four trials were included; most (44/54) had follow-up <1 year. Among 14,245 patients, 63 developed a malignancy. While most Peto ORs were >1, they had wide 95% CI and p >0.05. The overall Peto OR comparing biologics with non-biologics was 1.42 (95% CI 0.80–2.53). Only interleukin-17 inhibitors in peripheral SpA had p <0.05 (Peto OR 2.77, 95% CI 1.07–7.13); the posterior probability that the risk was higher than non-biologics was 98%. Stratified analyses revealed no consistent trend by prior exposure to biologics, duration of follow-up, study quality, study-arm crossover, analytical approaches and type of malignancy. Conclusions: Our findings indicate no overall elevated risk of malignancy with biologics in SpA. As our meta-analyses are unable to conclude on the long-term risk, long-term pharmacovigilance of biologics in SpA may still be warranted.

Substituent Distribution and Clouding Behavior of Hydroxypropyl Methyl Cellulose Analyzed Using Enzymatic Degradation

2006 ◽  
Vol 7 (12) ◽  
pp. 3474-3481 ◽  
Author(s):  
Herje Schagerlöf ◽  
Marika Johansson ◽  
Sara Richardson ◽  
Gunnar Brinkmalm ◽  
Bengt Wittgren ◽  
...  
Keyword(s):  
Enzymatic Degradation ◽  
Methyl Cellulose ◽  
Substituent Distribution ◽  
Hydroxypropyl Methyl Cellulose

scholarly journals Skin and bubble formation in films made of methyl nanocellulose, hydrophobically modified ethyl(hydroxyethyl)cellulose and microfibrillated cellulose

Cellulose ◽  
2020 ◽  
Author(s):  
Johanna Lyytikäinen ◽  
Maria Morits ◽  
Monika Österberg ◽  
Isto Heiskanen ◽  
Kaj Backfolk
Keyword(s):  
Methyl Cellulose ◽  
Microfibrillated Cellulose ◽  
Hydroxyethyl Cellulose ◽  
Effect Of Temperature ◽  
Cellulose Derivatives ◽  
Air Bubbles ◽  
Oxygen Transmission Rate ◽  
Hydrophobically Modified ◽  
Film Forming ◽  
Ethyl Hydroxyethyl Cellulose

AbstractThe use of nanomaterials and polymers from renewable resources is important in the search for sustainable alternatives to plastic-based packaging materials and films. In this work, self-supporting thin films prepared from derivatized and non-derivatized nanocellulose and cellulose derivatives were studied. The effect of drying temperature on the film-forming behavior of compositions comprising hydrophobically modified ethyl(hydroxyethyl)cellulose (EHEC), native microfibrillated cellulose (MFC) and nanocellulose made from methyl cellulose was determined. The interaction between the components was assessed from viscosity measurements made at different temperatures, the result being linked to a thermal-dependent association during liquid evaporation, and the subsequent barrier and film-forming properties. The effect of temperature on suspensions was clearly different between the materials, confirming that there were differences in interaction and association between EHEC–MFC and methyl nanocellulose–MFC compositions. The amphiphilic EHEC affected both the suspension homogeneity and the film properties. Air bubbles were formed under certain conditions and composition particularly in MFC films, dependent on the drying procedure. The presence of air bubbles did not affect the oxygen transmission rate or the oil and grease resistance. An increasing amount of MFC improved the oxygen barrier properties of the films.

scholarly journals The Nordic Twin Study on Cancer — NorTwinCan

2019 ◽  
Vol 22 (6) ◽  
pp. 817-823
Author(s):  
Jennifer R. Harris ◽  
Jacob Hjelmborg ◽  
Hans-Olov Adami ◽  
Kamila Czene ◽  
Lorelei Mucci ◽  
...  
Keyword(s):  
Critical Role ◽  
Familial Risk ◽  
Twin Studies ◽  
Population Based ◽  
Cancer Etiology ◽  
Incident Cancer ◽  
Incidence And Mortality ◽  
Analytical Approaches ◽  
Country Specific

AbstractNordic twin studies have played a critical role in understanding cancer etiology and elucidating the nature of familial effects on site-specific cancers. The NorTwinCan consortium is a collaborative effort that capitalizes on unique research advantages made possible through the Nordic system of registries. It was constructed by linking the population-based twin registries of Denmark, Finland, Norway and Sweden to their country-specific national cancer and cause-of-death registries. These linkages enable the twins to be followed many decades for cancer incidence and mortality. To date, two major linkages have been conducted: NorTwinCan I in 2011–2012 and NorTwinCan II in 2018. Overall, there are 315,413 eligible twins, 57,236 incident cancer cases and 58 years of follow-up, on average. In the initial phases of our work, NorTwinCan established the world’s most comprehensive twin database for studying cancer, developed novel analytical approaches tailored to address specific research considerations within the context of the Nordic data and leveraged these models and data in research publications that provide the most accurate estimates of heritability and familial risk of cancers reported in the literature to date. Our findings indicate an excess familial risk for nearly all cancers and demonstrate that the incidence of cancer among twins mirrors the rate in the general population. They also revealed that twin concordance for cancer most often manifests across, rather than within, cancer sites, and we are currently focusing on the analysis of these cross-cancer associations.

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