The effects of coating structure and water-holding capacity on the oxygen-scavenging ability of enzymes embedded in the coating layer

Enzymes catalyzing oxygen scavenging were embedded in latex-based coatings with and without barrier kaolin clay to produce material for active packages. The clay was used to create a porous structure, and the closed-structure matrix consisted of a biopolymer comprising either starch or gelatin to increase the water uptake of the coating. The effects of the porous open structure and of the water uptake of the coated layer on the oxygen-scavenging ability of the embedded enzymes were examined at both 75% and 100% relative humidity. The results showed that the porous clay structure led to higher oxygen-scavenging capacity than that of a closed structure at both test conditions by enabling a high diffusion rate for oxygen and glucose to the active sites of the enzymes. The addition of a water-holding biopolymer did not always significantly affect the oxygen-scavenging capacity. However for a less-porous layer at 100% relative humidity, an increase in the amount of biopolymer resulted in an increase in oxygen-scavenging capacity. The results were treated statistically using multiple-factor analysis where the most important factor for the oxygen-scavenging ability was found to be the addition of clay. The coatings were also characterized with respect to water vapor uptake, overall migration, porosity, and scanning electron microscopy images.

Download Full-text

First global assessment of modelled aerosol hygroscopicity in the context of other aerosol optical properties

10.5194/egusphere-egu21-15340 ◽

2021 ◽

Author(s):

Maria Ángeles Burgos Simón ◽

Elisabeth Andrews ◽

Gloria Titos ◽

Angela Benedetti ◽

Huisheng Bian ◽

...

Keyword(s):

Optical Properties ◽

Light Scattering ◽

Relative Humidity ◽

Water Uptake ◽

Chem Phys ◽

Earth System ◽

Aerosol Optical Properties ◽

System Models ◽

Earth System Models

The particle hygroscopic growth impacts the optical properties of aerosols and, in turn, affects the aerosol-radiation interaction and calculation of the Earth&#8217;s radiative balance. The dependence of particle light scattering on relative humidity (RH) can be described by the scattering enhancement factor f(RH), defined as the ratio between the particle light scattering coefficient at a given RH divided by its dry value.The first effort of the AeroCom Phase III &#8211; INSITU experiment was to develop an observational dataset of scattering enhancement values at 26 sites to study the uptake of water by atmospheric aerosols, and evaluate f(RH) globally (Burgos et al., 2019). Model outputs from 10 Earth System Models (CAM, CAM-ATRAS, CAM-Oslo, GEOS-Chem, GEOS-GOCART, MERRAero, TM5, OsloCTM3, IFS-AER, and ECMWF) were then evaluated against this in-situ dataset. Building on these results, we investigate f(RH) in the context of other aerosol optical and chemical properties, making use of the same 10 Earth System Models (ESMs) and in-situ measurements as in Burgos et al. (2020) and Titos et al. (2021).Given the difficulties of deploying and maintaining instrumentation for long-term, accurate and comprehensive f(RH) observations, it is desirable to find an observational proxy for f(RH). This observation-based proxy would also need to be reproduced in modelling space. Our aim here is to evaluate how ESMs currently represent the relationship between f(RH), scattering &#197;ngstr&#246;m exponent (SAE), and single scattering albedo (SSA). This work helps to identify current challenges in modelling water-uptake by aerosols and their impact on aerosol optical properties within Earth system models.We start by analyzing the behavior of SSA with RH, finding the expected increase with RH for all site types and models. Then, we analyze the three variables together (f(RH)-SSA-SAE relationship). Results show that hygroscopic particles tend to be bigger and scatter more than non-hygroscopic small particles, though variability within models is noticeable. This relationship can be further studied by relating SAE to model chemistry, by selecting those grid points dominated by a single chemical component (mass mixing ratios > 90%). Finally, we analyze model performance at three specific sites representing different aerosol types: Arctic, marine and rural. At these sites, the model data can be exactly temporally and spatially collocated with the observations, which should help to identify the models which exhibit better agreement with measurements and for which aerosol type.&#160;Burgos, M.A.&#160;et al.:&#160;A global view on the effect of water uptake on aerosol particle light scattering.&#160;Sci Data&#160;6,&#160;157. https://doi.org/10.1038/s41597-019-0158-7, 2019.Burgos, M.A. et al.: A global model&#8211;measurement evaluation of particle light scattering coefficients at elevated relative humidity, Atmos. Chem. Phys., 20, 10231&#8211;10258, https://doi.org/10.5194/acp-20-10231-2020, 2020.Titos, G. et al.: A global study of hygroscopicity-driven light scattering enhancement in the context of other in-situ aerosol optical properties, Atmos. Chem. Phys. Discuss. [preprint], https://doi.org/10.5194/acp-2020-1250, in review, 2020.

Download Full-text

Lobaria amplissima thalli with external cephalodia need more rain than thalli without

The Lichenologist ◽

10.1017/s0024282919000197 ◽

2019 ◽

Vol 51 (3) ◽

pp. 281-286 ◽

Cited By ~ 2

Author(s):

Yngvar GAUSLAA ◽

Stina JOHLANDER ◽

Björn NORDÉN

Keyword(s):

Distribution Pattern ◽

Water Uptake ◽

Water Holding Capacity ◽

Climatic Gradient ◽

Humid Air ◽

Internal Water ◽

The Mean ◽

Water Holding

AbstractHydration traits determine much of a lichen’s distribution pattern along a climatic gradient but the mechanisms involved are still incompletely known. A higher abundance of large external cephalodia in wet oceanic than in drier climates has previously been reported in Lobaria amplissima. This study aims to quantify how much more rain L. amplissima thalli with external cephalodia would need to fill their internal water holding capacity (WHCinternal) than thalli without. The mean WHCinternal was 1·8 times higher in thalli with external cephalodia than in those without. The WHCinternal when converted to mm rain needed to saturate an average specimen was 1·37 mm (min–max: 0·55–3·8 mm) for a cephalodiate thallus, whereas an average thallus without external cephalodia needed just 0·76 mm (min–max: 0·36–1·3 mm). Known dewfall rates and rates of water uptake from humid air are far below what is needed to saturate even the cephalodiate thallus with the lowest WHCinternal, implying a stronger dependency on rain for thalli with external cephalodia. Thus, the observed trends in this study are consistent with earlier reports of decreasing frequency of external cephalodia from wet to drier climates.

Download Full-text

Aerosol size and relative humidity: Water uptake by mixtures of salts

Tellus ◽

10.1111/j.2153-3490.1979.tb00929.x ◽

1979 ◽

Vol 31 (6) ◽

pp. 478-486 ◽

Cited By ~ 26

Author(s):

GOTTFRIED HÄNEL ◽

BRIGITTE ZANKL

Keyword(s):

Relative Humidity ◽

Water Uptake

Download Full-text

Oxygen-Scavenging Multilayered Biopapers Containing Palladium Nanoparticles Obtained by the Electrospinning Coating Technique

Nanomaterials ◽

10.3390/nano9020262 ◽

2019 ◽

Vol 9 (2) ◽

pp. 262 ◽

Cited By ~ 9

Author(s):

Adriane Cherpinski ◽

Piotr Szewczyk ◽

Adam Gruszczyński ◽

Urszula Stachewicz ◽

Jose Lagaron

Keyword(s):

Palladium Nanoparticles ◽

Food Packaging ◽

Ion Beam ◽

Barrier Properties ◽

Oxygen Absorption ◽

Coating Technique ◽

Water Barrier ◽

Oxygen Scavenging ◽

Scavenging Capacity ◽

Focus Ion Beam

The main goal of this study was to obtain, for the first time, highly efficient water barrier and oxygen-scavenging multilayered electrospun biopaper coatings of biodegradable polymers over conventional cellulose paper, using the electrospinning coating technique. In order to do so, poly(3-hydroxybutyrate) (PHB) and polycaprolactone (PCL) polymer-containing palladium nanoparticles (PdNPs) were electrospun over paper, and the morphology, thermal properties, water vapor barrier, and oxygen absorption properties of nanocomposites and multilayers were investigated. In order to reduce the porosity, and to enhance the barrier properties and interlayer adhesion, the biopapers were annealed after electrospinning. A previous study showed that electrospun PHB-containing PdNP did show significant oxygen scavenging capacity, but this was strongly reduced after annealing, a process that is necessary to form a continuous film with the water barrier. The results in the current work indicate that the PdNP were better dispersed and distributed in the PCL matrix, as suggested by focus ion beam-scanning electron microscopy (FIB-SEM) experiments, and that the Pd enhanced, to some extent, the onset of PCL degradation. More importantly, the PCL/PdNP nanobiopaper exhibited much higher oxygen scavenging capacity than the homologous PHB/PdNP, due to most likely, the higher oxygen permeability of the PCL polymer and the somewhat higher dispersion of the Pd. The passive and active multilayered biopapers developed here may be of significant relevance to put forward the next generation of fully biodegradable barrier papers of interest in, for instance, food packaging.

Download Full-text

Effect of Temperature on the Yield of Lignin Extracted Using Microwave-Assisted Acetosolv from Empty Fruit Bunch Fibers

Materials Science Forum ◽

10.4028/www.scientific.net/msf.981.240 ◽

2020 ◽

Vol 981 ◽

pp. 240-244

Author(s):

Muhammad Nor Arifin Yaakob ◽

Rasidi Roslan ◽

Nurjannah Salim ◽

Siti Noor Hidayah Mustapha ◽

Sarani Zakaria ◽

...

Keyword(s):

Active Sites ◽

High Efficiency ◽

Paper Industry ◽

Acid Catalyst ◽

Biomass Composition ◽

Effect Of Temperature ◽

Composition Analysis ◽

Empty Fruit Bunch ◽

Microwave Assisted ◽

Microscopy Images

Acetosolv technique is considered as one of the best alternative way to extract technical lignin from biomass as it has high efficiency and environmentally friendly. In this study, microwave-assisted acetosolv technique were used to extract lignin from oil palm empty fruit bunch (OPEFB) in the presence of 3% sulfuric acid catalyst reacted at various temperature. The yield of the extracted acetosolv lignin were calculated using modified Technical Association of the Pulp and Paper Industry biomass composition analysis (TAPPI) method. The result showed that, as the temperature increased from 90 to 110 °C, the yield of lignin extracted also increase from 43.07 to 76.98%. The presence of guaiacyl and p-coumarate indicates the presence of active sites at C-3 and C-5 of aromatic ring for polymerization reactions. Scanning Electron Microscopy images showed that removal of lignin are intensified as the microwave-assisted acetosolv temperature increased.

Download Full-text

Non-invasive diagnosis of viability in seeds and lichens by infrared thermography under controlled environmental conditions

Plant Methods ◽

10.1186/s13007-019-0531-8 ◽

2019 ◽

Vol 15 (1) ◽

Author(s):

Beatriz Fernández-Marín ◽

Othmar Buchner ◽

Gerald Kastberger ◽

Federica Piombino ◽

José Ignacio García-Plazaola ◽

...

Keyword(s):

Relative Humidity ◽

Infrared Thermography ◽

Water Uptake ◽

Imaging Techniques ◽

Time Windows ◽

Life Forms ◽

Aerobic Metabolism ◽

Gaseous Atmosphere ◽

Non Invasive ◽

Pea Seeds

Abstract Background Non-invasive procedures for the diagnosis of viability of plant or fungal tissues would be valuable for scientific, industrial and biomonitoring purposes. Previous studies showed that infrared thermography (IRT) enables non-invasive assessment of the viability of individual "orthodox" (i.e. desiccation tolerant) seeds upon water uptake. However, this method was not tested for rehydrating tissues of other desiccation tolerant life forms. Furthermore, evaporative cooling could obscure the effects of metabolic processes that contribute to heating and cooling, but its effects on the shape of the "thermal fingerprints" have not been explored. Here, we further adapted this method using a purpose-built chamber to control relative humidity (RH) and gaseous atmosphere. This enabled us to test (i) the influence of relative humidity on the thermal fingerprints during the imbibition of Pisum sativum (Garden pea) seeds, (ii) whether thermal fingerprints can be correlated with viability in lichens, and (iii) to assess the potential influence of aerobic metabolism on thermal fingerprints by controlling the oxygen concentration in the gaseous atmosphere around the samples. Finally, we developed a method to artificially "age" lichens and validated the IRT-based method to assess lichen viability in three lichen species. Results Using either 30% or 100% RH during imbibition of pea seeds, we showed that "live" and "dead" seeds produced clearly discernible "thermal fingerprints", which significantly differed by > |0.15| °C in defined time windows, and that RH affected the shape of these thermal fingerprints. We demonstrated that IRT can also be used to assess the viability of the lichens Lobaria pulmonaria, Pseudevernia furfuracea and Peltigera leucophlebia. No clear relationship between aerobic metabolism and the shape of thermal fingerprints was found. Conclusions Infrared thermography appears to be a promising method for the diagnosis of viability of desiccation-tolerant tissues at early stages of water uptake. For seeds, it is possible to diagnose viability within the first hours of rehydration, after which time they can still be re-dried and stored until further use. We envisage our work as a baseline study for the use of IR imaging techniques to investigate physiological heterogeneity of desiccation tolerant life forms such as lichens, which can be used for biomonitoring, and for sorting live and dead seeds, which is potentially useful for the seed trade.

Download Full-text

Hygroscopic behavior and chemical composition evolution of internally mixed aerosols composed of oxalic acid and ammonium sulfate

10.5194/acp-2017-454 ◽

2017 ◽

Author(s):

Xiaowei Wang ◽

Bo Jing ◽

Fang Tan ◽

Jiabi Ma ◽

Yunhong Zhang ◽

...

Keyword(s):

Growth Factors ◽

Chemical Composition ◽

Relative Humidity ◽

Oxalic Acid ◽

Ammonium Sulfate ◽

Water Uptake ◽

Atmospheric Environment ◽

Dehydration Process ◽

Hygroscopic Properties ◽

Ammonium Hydrogen

Abstract. Although water uptake of aerosols plays an important role in the atmospheric environment, the effects of interactions between components on chemical composition and hygroscopicity of aerosols are still not well constrained. The hygroscopic properties and phase transformation of oxalic acid (OA) and mixed particles composed of ammonium sulfate (AS) and OA with different organic to inorganic molar ratios (OIRs) have been investigated by using confocal Raman spectroscopy. It is found that OA droplets first crystallize to form oxalic acid dihydrate at 77 % relative humidity (RH), and further lose crystalline water to convert into anhydrous oxalic acid around 5 % RH during the dehydration process. The deliquescence and efflorescence point for AS is determined to be 80.1 ± 1.5 % RH and 44.3 ± 2.5 % RH, respectively. The observed efflorescence relative humidity (ERH) for mixed OA/AS droplets with OIRs of 1:3, 1:1 and 3:1 is 34.4 ± 2.0 % RH, 44.3 ± 2.5 % RH and 64.4 ± 3.0 % RH, respectively, indicating the elevated OA content appears to favor the crystallization of mixed systems at higher RH. However, the partial deliquescence relative humidity (DRH) for mixed OA/AS particles with OIR of 1:3 and 1:1 is observed to occur at 81.1 ± 1.5 % RH and 77 ± 1.0 % RH, respectively. The Raman spectra of mixed OA/AS droplets indicate the formation of ammonium hydrogen oxalate (NH4HC2O4) and ammonium hydrogen sulfate (NH4HSO4) from interactions between OA and AS in aerosols after slow dehydration process in the time scale of hours, which considerably influence the subsequent deliquescence behavior of internally mixed particles with different OIRs. The mixed OA/AS particles with 3:1 ratio exhibit no deliquescence transition over the RH range studied due to the considerable transformation of (NH4)2SO4 into nonhygroscopic NH4HC2O4. Although the hygroscopic growth of mixed OA/AS droplets is comparable to that of AS or OA at high RH during the dehydration process, Raman growth factors of mixed particles after deliquescence are substantially lower than those of mixed OA/AS droplets during the efflorescence process and further decrease with elevated OA content. The discrepancies for Raman growth factors of mixed OA/AS particles between the dehydration and hydration process at high RH can be attributed to the significant formation of NH4HC2O4 and residual OA, which remain solid at high RH and thus result in less water uptake of mixed particles. These findings improve the understanding of the role of reactions between dicarboxylic acid and inorganic salt in the chemical and physical properties of aerosol particles, and might have important implications for atmospheric chemistry.

Download Full-text

Aerosol size and relative humidity: Water uptake by mixtures of salts

Tellus ◽

10.3402/tellusa.v31i6.10465 ◽

1979 ◽

Vol 31 (6) ◽

pp. 478-486 ◽

Cited By ~ 14

Author(s):

Gottfried Hanel ◽

Brigitte Zankl

Keyword(s):

Relative Humidity ◽

Water Uptake

Download Full-text

Impact of palmitic acid coating on the water uptake and loss of ammonium sulfate particles

Atmospheric Chemistry and Physics ◽

10.5194/acp-5-1951-2005 ◽

2005 ◽

Vol 5 (7) ◽

pp. 1951-1961 ◽

Cited By ~ 54

Author(s):

R. M. Garland ◽

M. E. Wise ◽

M. R. Beaver ◽

H. L. DeWitt ◽

A. C. Aiken ◽

...

Keyword(s):

Relative Humidity ◽

Palmitic Acid ◽

Ammonium Sulfate ◽

Water Uptake ◽

Atmospheric Aerosols ◽

Acid Vapor ◽

Aerosol Mass ◽

Aerosol Mass Spectrometry ◽

Transmission Electron ◽

Mixed Water

Abstract. While water insoluble organics are prevalent in the atmosphere, it is not clear how the presence of such species alters the chemical and physical properties of atmospheric aerosols. Here we use a combination of FTIR spectroscopy, Transmission Electron Microscopy (TEM) and Aerosol Mass Spectrometry (AMS) to characterize ammonium sulfate particles coated with palmitic acid. Coated aerosols were generated by atomizing pure ammonium sulfate, mixing the particles with a heated flow of nitrogen with palmitic acid vapor, and then flowing the mixture through an in-line oven to create internally mixed particles. The mixing state of the particles was probed using the AMS data and images from the TEM. Both of these probes suggest that the particles were internally mixed. Water uptake by the mixed particles was then probed at 273 K. It was found that for ammonium sulfate containing ~20 wt% palmitic acid the deliquescence relative humidity (DRH) was the same as for pure ammonium sulfate (80±3% RH). For particles with ~50 wt% palmitic acid however, the mixed particles began to take up water at relative humidities as low at 69% and continued to slowly take up water to 85% RH without fully deliquescing. In addition to studies of water uptake, water loss was also investigated. Here coatings of up to 50 wt% had no impact on the efflorescence relative humidity. These studies suggest that even if insoluble substances coat salt particles in the atmosphere, there may be relatively little effect on the resulting water uptake and loss.

Download Full-text