scholarly journals The Effect of Pollutant Gases on Surfactant Migration in Acrylic Emulsion Films: A Comparative Study and Preliminary Evaluation of Surface Cleaning

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1941
Author(s):  
Laura Pagnin ◽  
Rita Wiesinger ◽  
Ayse Nur Koyun ◽  
Manfred Schreiner
Keyword(s):  
Degradation Products ◽  
Morphological Changes ◽  
Accelerated Aging ◽  
Surface Cleaning ◽  
Preliminary Evaluation ◽  
Reaction Products ◽  
Atmospheric Pollutant ◽  
Acrylic Emulsion ◽  
Emulsion Films ◽  
Pollutant Gases

From their first employment in the 1950s, acrylic emulsions have remained widely used as art material today. Although under certain deteriorating conditions they are very stable, if exposed to high humidity and atmospheric pollutant gases, their structural and chemical conformation is strongly affected. Dealing with the resulting surfactant migration, various cleaning treatments were considered over the years. However, their choice remains difficult as they easily alter the acrylic component, especially if in contact with aqueous solutions. The present study focuses on investigating the stability of acrylic emulsion films exposed to accelerated aging by various pollutant gases. Firstly, a comparative analytical study was carried out in order to morphologically (by 3D optical and Atomic Force Microscopy) and chemically (by Raman and Infrared spectroscopy) characterize the reactions and degradation products. Subsequently, two water-based cleaning treatments were tested, and a preliminary evaluation of their cleaning effectiveness was performed. The results show that the reaction of atmospheric gas pollutants with water molecules in moisture leads to acidic reaction products that attack the acrylic matrix and favor the migration of the surfactant to the surface. The effectiveness of cleaning treatments depends on the aging conditions applied, which further lead to different surface morphological changes.

Characterization of dissolved material during the initial phase of softwood kraft pulping

TAPPI Journal ◽  
2013 ◽  
Vol 12 (1) ◽  
pp. 37-43 ◽  
Author(s):  
HANNU PAKKANEN ◽  
TEEMU PALOHEIMO ◽  
RAIMO ALÉN
Keyword(s):  
Mass Transfer ◽  
Molecular Mass ◽  
Initial Phase ◽  
Degradation Products ◽  
Kraft Pulping ◽  
Reaction Products ◽  
Cooking Temperature ◽  
Molecular Masses ◽  
Aliphatic Carboxylic Acids

The influence of various cooking parameters, such as effective alkali, cooking temperature, and cooking time on the formation of high molecular mass lignin-derived and low molecular mass carbohydrates-derived (aliphatic carboxylic acids) degradation products, mainly during the initial phase of softwood kraft pulping was studied. In addition, the mass transfer of all of these degradation products was clarified based on their concentrations in the cooking liquor inside and outside of the chips. The results indicated that the degradation of the major hemicellulose component, galactoglucomannan, typically was dependent on temperature, and the maximum degradation amount was about 60%. In addition, about 60 min at 284°F (140°C) was needed for leveling off the concentrations of the characteristic reaction products (3,4-dideoxy-pentonic and glucoisosaccharinic acids) between these cooking liquors. Compared with low molecular mass aliphatic acids, the mass transfer of soluble lignin fragments with much higher molecular masses was clearly slower.

Long-path monitoring of atmospheric pollutant gases

1976 ◽  
Vol 8 (2) ◽  
pp. 194-196 ◽  
Author(s):  
H. Tannenbaum ◽  
R. L. Byer ◽  
S. F. Clifford ◽  
K. S. Fu ◽  
E. D. Hinkley ◽  
...  
Keyword(s):  
Atmospheric Pollutant ◽  
Pollutant Gases

scholarly journals INTEMPERISMO ARTIFICIAL DE QUATRO REVESTIMENTOS APLICADOS EM MADEIRAS DE DUAS ESPÉCIES FLORESTAIS

Nativa ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 313 ◽  
Author(s):  
Aline Krolow Soares ◽  
Roberto Lessa Pereira ◽  
Pedro Henrique Gonzalez de Cademartori ◽  
Henrique Weber Dalla Costa ◽  
Darci Alberto Gatto
Keyword(s):  
Morphological Changes ◽  
Eucalyptus Grandis ◽  
Accelerated Aging ◽  
Surface Wettability ◽  
Forest Species ◽  
Artificial Weathering ◽  
Color Changes ◽  
Accelerated Aging Test ◽  
Aging Test ◽  
Weathering Resistance

O presente estudo teve como objetivo investigar a resistência ao intemperismo artificial de quatro revestimentos aplicados nas madeiras de duas espécies florestais. Para tal, foram utilizadas seis árvores de Eucalyptus grandis e três árvores de Tetrorchidium rubrivenium as quais foram desdobradas para confecção de 50 amostras para cada espécie, com dimensões de 5,0x7,0x1,0cm (largura, comprimento e espessura, respectivamente). A superfície das madeiras foi revestida com quatro acabamentos: polistein, verniz marítimo, tinta branca base óleo e tinta branca base água. As amostras sem revestimento e revestidas foram submetidas ao ensaio de envelhecimento acelerado durante 480 horas. A resistência ao intemperismo artificial foi avaliada por meio das modificações colorimétricas e morfológicas ao longo da exposição das madeiras e em função da molhabilidade superficial. Os principais resultados mostraram que a superfície das madeiras  tendeu a tons opacos após exposição de 480 horas. Foi observado que os revestimentos não evitaram o aumento da molhabilidade superficial. Após todo o período de exposição, as madeiras não apresentaram modificações morfológicas tais como rachaduras e descascamento dos revestimentos, o que denota importante característica de proteção à madeira.Palavras-chave: Eucalyptus, canemaçu, modificação da superfície, envelhecimento acelerado, durabilidade da madeira. ARTIFICIAL WEATHERING OF FOUR COATINGS APPLIED ON WOODS OF TWO FOREST SPECIES ABSTRACT:The present study aimed to investigate the resistance to artificial weathering of four coatings applied on wood from two forest species. Six trees of Eucalyptus grandis and three trees of Tetrorchidium rubrivenium were cut to produce 50 wood samples for each species with dimensions of 5.0x7.0x1.0 cm (width, length and thickness, respectively). Wood surface was coated with four finishing products: polistein, marine varnish, oil-based white paint and water-based white paint. The uncoated and coated wood samples were subjected to accelerated aging test for 480h. The artificial weathering resistance was evaluated by color changes and surface wettability. The main results showed the coated woods tend to opaque tones after the exposure for 480h. The coatings did not avoid the increase of the surface wettability. After the exposure, both woods did not present morphological changes, such as cracks and peeling into the coatings, which represent relevant characteristics for wood protection.Keywords: Eucalyptus, canemaçu, surface modification, accelerated aging, wood durability. DOI:

scholarly journals Rapid Detection of Imipenem Resistance in Gram-Negative Bacteria Using Tabletop Scanning Electron Microscopy: A Preliminary Evaluation

2021 ◽  
Vol 12 ◽  
Author(s):  
Gabriel Haddad ◽  
Anthony Fontanini ◽  
Sara Bellali ◽  
Tatsuki Takakura ◽  
Yusuke Ominami ◽  
...  
Keyword(s):  
Bacterial Resistance ◽  
Morphological Changes ◽  
Carbapenem Resistance ◽  
Preliminary Evaluation ◽  
Gram Negative Bacteria ◽  
Blind Test ◽  
Gram Negative ◽  
Length Width ◽  
Imipenem Resistance ◽  
Scanning Electron

Background: Enabling faster Antimicrobial Susceptibility Testing (AST) is critical, especially to detect antibiotic resistance, to provide rapid and appropriate therapy and to improve clinical outcomes. Although several standard and automated culture-based methods are available and widely used, these techniques take between 18 and 24 h to provide robust results. Faster techniques are needed to reduce the delay between test and results.Methods: Here we present a high throughput AST method using a new generation of tabletop scanning electron microscope, to evaluate bacterial ultra-structural modifications associated with susceptibilities to imipenem as a proof of concept. A total of 71 reference and clinical strains of Gram-negative bacteria were used to evaluate susceptibility toward imipenem after 30, 60, and 90 min of incubation. The length, width and electron density of bacteria were measured and compared between imipenem susceptible and resistant strains.Results: We correlated the presence of these morphological changes to the bacterial susceptibility and their absence to the bacterial resistance (e.g., Pseudomonas aeruginosa length without [2.24 ± 0.61 μm] and with [2.50 ± 0.68 μm] imipenem after 30 min [p = 3.032E-15]; Escherichia coli width without [0.92 ± 0.07 μm] and with [1.28 ± 0.19 μm] imipenem after 60 min [p = 1.242E-103]). We validated our method by a blind test on a series of 58 clinical isolates where all strains were correctly classified as susceptible or resistant toward imipenem.Conclusion: This method could be a potential tool for rapidly identifying carbapenem-resistance in Enterobacterales in clinical microbiology laboratories in <2 h, allowing the empirical treatment of patients to be rapidly adjusted.

Impaired Function and Altered Morphology in the Skeletal Muscles of Adult Men and Women with Type 1 Diabetes

2021 ◽  
Author(s):  
Athan G Dial ◽  
Cynthia M F Monaco ◽  
Grace K Grafham ◽  
Tirth P Patel ◽  
Mark A Tarnopolsky ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Type 1 Diabetes ◽  
Muscle Function ◽  
Morphological Changes ◽  
Venous Blood ◽  
Accelerated Aging ◽  
Myosin Heavy Chain Isoforms ◽  
Hybrid Fibers ◽  
Skeletal Muscle Function

Abstract Context Previous investigations on skeletal muscle health in type 1 diabetes (T1D) has generally focused on later stages of disease progression where comorbidities are present and are posited as a primary mechanism of muscle dysfunction. Objective To investigate skeletal muscle function and morphology across the adult lifespan in those with and without T1D. Design Participants underwent maximal contraction (MVC) testing, resting muscle biopsy and venous blood sampling. Setting Procedures in this study were undertaken at the McMaster University Medical Centre. Participants Sixty-five healthy adult (18-78 years old) men/males and women/females [T1D=34; control=31] matched for age/biological sex/body mass index (BMI)/self-reported physical activity levels were included. Main Outcome Measures Our primary measure in this study was MVC, with supporting histological/immunofluorescent measures. Results After 35 years of age (‘older adults’), MVC declined quicker in T1D subjects compared to controls. Loss of strength in T1D was accompanied by morphological changes associated with accelerated aging. Type 1 myofiber grouping was higher in T1D, and the groups were larger and more numerous than in controls. Older T1D females exhibited more myofibers expressing multiple myosin heavy chain isoforms (hybrid fibers) than controls, another feature of accelerated aging. Conversely, T1D males exhibited a shift towards type 2 fibers, with less evidence of myofiber grouping or hybrid fibers. Conclusions These data suggest impairments to skeletal muscle function and morphology exist in T1D. The decline in strength with T1D is accelerated after 35 years of age and may be responsible for the earlier onset of frailty which characterizes those with diabetes.

scholarly journals Strecker degradation products of aspartic and glutamic acids and their amides

2013 ◽  
Vol 19 (No. 2) ◽  
pp. 41-45 ◽  
Author(s):  
J. Rössner ◽  
J. Velíšek ◽  
F. Pudil ◽  
J. Davídek
Keyword(s):  
Amino Acids ◽  
Glutamic Acid ◽  
Aspartic Acid ◽  
Degradation Products ◽  
Dicarboxylic Acids ◽  
Reaction Products ◽  
Degradation Reactions ◽  
Strecker Aldehydes ◽  
Volatile Products ◽  
Acid Acid

Aspartic and glutamic acids, asparagine and glutamine were oxidised with either potassium peroxodisulphate or glyoxal. Nonvolatile products were derivatised and analysed by GC/FID and GC/MS. Volatile reaction products were isolated and analysed by the same methods. It was found that the degradation reactions of amino acids are complex. Amino acids are principally degraded via the corresponding a-keto acids to Strecker aldehydes (aspartic acid to oxalacetic and 3-oxopropionic acids and glutamic acid to a-ketoglutaric and 4-oxobutyric acids), which are unstable and decomposed by decarboxylation to the corresponding aldehydes. Aspartic acid also eliminates ammonia and yields fumaric acid whereas glutamic acid gives rise to an imine, pyroglutamic acid. A recombination of free radicals leads to dicarboxylic acids (succinic acid from aspartic acid, succinic, glutaric and adipic acids from glutamic acid). The major volatile products (besides the aldehydes) are lower carboxylic acids (acetic acid from aspartic acid and propionic acid acid from glutamic acid) that can at least partly arise by radical reactions. In both quality and quantity terms, a higher amount of degradation products arises by oxidation of amino acids by peroxodisulphate.

Effect of pollutant gases on chlorophyll a multilayer

1981 ◽  
Vol 59 (15) ◽  
pp. 2402-2411 ◽  
Author(s):  
Camille Chapados ◽  
Denis Germain ◽  
Roger M. Leblanc
Keyword(s):  
Ir Spectra ◽  
Atomic Absorption ◽  
Chlorophyll A ◽  
Direct Effect ◽  
Time Effect ◽  
Reaction Products ◽  
Pheophytin A ◽  
Chl A ◽  
End Products ◽  
Pollutant Gases

The aim of this paper is to examine the direct effect of polluting gases on chlorophyll a (chl a) multilayer arrays. The pollutants studied are CO, CO2, SO2, H2S, NO, and NO2. Electronic and infrared spectroscopies were used to monitor the time effect of the polluting gases on chl a molecules. TLC, atomic absorption, and electronic spectroscopies were used to characterise the reaction products. The results show that neither CO nor CO2 affect the chl a molecules in the multilayer arrays. Upon exposure to SO2, we notice many modifications on the electronic and ir spectra. All the evidence confirms that one of the reaction products is pheophytin a. A mechanism is presented to explain the reaction of SO2 with chl a. The effect of H2S on chl a is less pronounced than that of SO2, but the end products are the same. NO and NO2 have exactly the same effect on the chl a multilayer. The reaction is much more drastic than the reaction of chl a with either SO2 or H2S. There is opening of the cycle and nitration of the chl a molecule.

scholarly journals Decomposition and Stabilization of Drugs. VIII. Reaction Products of Norphenylephrine with Degradation Products of Sugars

1973 ◽  
Vol 93 (7) ◽  
pp. 925-927 ◽  
Author(s):  
KAZUO KIGAZAWA ◽  
NORIKO IKARI ◽  
KAZUMI OHKUBO ◽  
HIDEKI IIMURA ◽  
SEIJI HAGA
Keyword(s):  
Degradation Products ◽  
Reaction Products

Thermal degradation of EDTA chelates in aqueous solution

1982 ◽  
Vol 60 (10) ◽  
pp. 1207-1213 ◽  
Author(s):  
Ramunas J. Motekaitis ◽  
X. B. Cox III ◽  
Patrick Taylor ◽  
Arthur E. Martell ◽  
Brad Miles ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Thermal Degradation ◽  
Elevated Temperatures ◽  
Degradation Products ◽  
Iminodiacetic Acid ◽  
Reaction Products ◽  
Degradation Rates ◽  
Lower Temperature Range ◽  
Higher Temperature ◽  
Lower Temperature

The thermal degradation of Ca(II), Mg(II), Zn(II), Fe(II), and Ni(II) chelates of EDTA was investigated in alkaline aqueous solution at elevated temperatures (230–310 °C). The kinetics of decomposition were followed by nmr, titrimetry, and spectrophotometry. Reaction products were identified through nmr and by gas chromatography. The relative order of degradation rates, as measured by the loss of EDTA, was found to be Mg(II) > Ca(II) > Zn(II) > Fe(II) > Ni(II). The main degradation products formed in the lower temperature range (~250 °C) are iminodiacetic acid, hydroxyethyliminodiacetic acid, and ethylene glycol. Higher temperature products are primarily dimethylamine and carbon dioxide. The rates of degradation of Ca(II), Mg(II), and Zn(II) EDTA chelates are considerably enhanced when either phosphate is present or a glass-lined autoclave is employed.

scholarly journals The Reactivity of Polyethylene Microplastics in Water under Low Oxygen Conditions Using Radiation Chemistry

Water ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3120
Author(s):  
Julie R. Peller ◽  
Stephen P. Mezyk ◽  
Sarah Shidler ◽  
Joe Castleman ◽  
Scott Kaiser ◽  
...  
Keyword(s):  
Surface Characterization ◽  
Solid Phase ◽  
Degradation Products ◽  
Morphological Changes ◽  
Aqueous Solubility ◽  
Radiation Chemistry ◽  
Dark Field ◽  
Gas Chromatography Mass Spectrometry ◽  
Low Oxygen ◽  
Oxygen Conditions

Polyethylene (PE) is an intensely utilized polymer, which has consequently led to it becoming a common environmental contaminant. PE and other plastic waste are known to be highly persistent in surface waters; however, chemical and physical changes do take place over time, dependent mostly on highly variable natural conditions, such as oxygen (O2) availability. Gamma radiation was used to generate reactive oxygen species, namely hydroxyl radicals, in initially aerated aqueous solutions to simulate the natural weathering of microplastics in waters where there are fluctuations and often depletions in dissolved O2. The headspace of the irradiated PE-containing solutions was probed for the formation of degradation products using solid-phase microextraction (SPME) fibers in combination with gas chromatography mass spectrometry (GCMS). The major species detected were n-dodecane, with trace levels of tridecane, 2-dodecanone, and hexadecane, which were believed to be predominately adsorbed in the PE microplastics in excess of their aqueous solubility limits. Surface characterization by Raman spectroscopy and light and dark field microscopy indicated no change in the chemical composition of the irradiated PE microplastics under low O2 to anaerobic conditions. However, morphological changes were observed, indicating radical combination reactions.

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