Probing the chemical and surface chemical modification of vessel cell walls during bleaching of eucalyptus pulp

Abstract Eucalyptus pulp is increasingly used for the manufacture of printing papers. However, its major drawback, the vessel picking, is still waiting for a solution. The detailed features and the characteristic behaviour of vessel elements (VEs) in pulp and paper processes are poorly understood. This study focusses on the chemistry, surface chemistry and morphology of eucalyptus VEs. These properties were followed through the changes introduced by different stages of elemental chlorine-free (ECF) bleaching, by studying separated VEs. Microprobe X-ray photoelectron spectroscopy (μ-XPS) and field emission-scanning electron microscopy (FE-SEM) were applied to elucidate the surface chemical composition and morphological ultrastructure, respectively. The bulk chemical composition was investigated among others by Py-GC/MS. Lignin was detected in vessels still after completed bleaching sequence, whereas the fibres were lignin-free. The vessel lignin was mainly composed by syringyl-type units. Surface coverage by lignin and amount of surface anionic groups were practically unaffected by bleaching. The vessel cell wall structure was observed to be layered in a complex way with no particular orientation of cellulose fibrils, and the different layers seemed to be exfoliated during different bleaching stages.

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Zooming in on surface chemical composition of soil microaggregates – Is there an effect of plants (Festuca)?

10.5194/egusphere-egu21-13760 ◽

2021 ◽

Author(s):

Susanne K Woche ◽

Stefan Dultz ◽

Robert Mikutta ◽

Klaus Kaiser ◽

Georg Guggenberger

Keyword(s):

Contact Angle ◽

Organic Matter ◽

Chemical Composition ◽

Photoelectron Spectroscopy ◽

Bare Soil ◽

Organic N ◽

Initial Contact ◽

Surface Chemical ◽

Surface Chemical Composition ◽

Fresh Organic Matter

Formation of soil microaggregates (SMA) is a surface-driven process and depends on mineral cementing and organic gluing agents. Yet, the role of plants in soil microaggregation by input of fresh organic matter remains little understood. In a mesocosm experiment silty Luvisol topsoil (<250&#160;&#181;m; original soil material) was incubated in absence (bare soil) and presence of plants (Festuca) and water-stable free and occluded SMA were isolated after 4, 12, and 30 weeks and investigated for the surface chemical composition by X-ray photoelectron spectroscopy (XPS) and for wetting properties by contact angle determination.Compared to the original soil, the surfaces of both free and occluded SMA tended to smaller O and larger C contents, thus a smaller O/C ratio, along with a slight increase in initial contact angle from about 10&#176; (original soil) to about 20&#176; (SMA). The O/C ratio decreased slightly further from 4 to 12 weeks, especially for bare soil without plants. Slightly greater C contents were detected for occluded than for free SMA, probably hinting at higher retention of organic matter on surfaces of microaggregates entrained in larger soil structures. For bare soil, a slightly greater N content was observed for free SMA while in the presence of Festuca free and occluded SMA had same N contents.Regardless of the presence of Festuca, C speciation indicated a lower proportion (in % of total C) of C=O/O-C-O and a higher proportion of C&#160;-&#160;C/C&#160;-&#160; H species for occluded than for free SMA, probably indicating less altered organic matter at the surfaces of occluded SMA. While the proportion of C=O/O-C-O species slightly decreased, that of C-&#160;C/C-H species slightly increased towards the end of the incubation. This may hint at some preferences in microbial respiration with respect to C compounds and formation of microbial metabolites. From N speciation a higher ratio between protonated and non-protonated organic N species (Np/Nnp) was indicated for Festuca than for bare soil after 4 and for 30 weeks of incubation, i.e., the presence of plants seems to impact N compounds present. The Np/Nnp ratio tended to decrease after 30 weeks compared to 4 weeks for both treatments, hinting on changes in N species present.In summary, aside some effect on N species present, results indicate rather incubation and SMA origin (free, occluded) than the presence of plants (Festuca) to impact surface chemical composition of the tested SMA. This suggests no defined contribution of plants and their products to formation of 250-53 &#181;m-sized SMA.

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Applying Cryo-X-ray Photoelectron Spectroscopy to Study the Surface Chemical Composition of Fungi and Viruses

Frontiers in Chemistry ◽

10.3389/fchem.2021.666853 ◽

2021 ◽

Vol 9 ◽

Author(s):

Andrey Shchukarev ◽

Emelie Backman ◽

Samuel Watts ◽

Stefan Salentinig ◽

Constantin F. Urban ◽

...

Keyword(s):

Chemical Composition ◽

Photoelectron Spectroscopy ◽

Biological Systems ◽

Building Blocks ◽

Model Organisms ◽

Surface Chemical ◽

Surface Layers ◽

Xps Spectra ◽

X Ray ◽

Surface Chemical Composition

Interaction between microorganisms and their surroundings are generally mediated via the cell wall or cell envelope. An understanding of the overall chemical composition of these surface layers may give clues on how these interactions occur and suggest mechanisms to manipulate them. This knowledge is key, for instance, in research aiming to reduce colonization of medical devices and device-related infections from different types of microorganisms. In this context, X-ray photoelectron spectroscopy (XPS) is a powerful technique as its analysis depth below 10 nm enables studies of the outermost surface structures of microorganism. Of specific interest for the study of biological systems is cryogenic XPS (cryo-XPS). This technique allows studies of intact fast-frozen hydrated samples without the need for pre-treatment procedures that may cause the cell structure to collapse or change due to the loss of water. Previously, cryo-XPS has been applied to study bacterial and algal surfaces with respect to their composition of lipids, polysaccharides and peptide (protein and/or peptidoglycan). This contribution focuses onto two other groups of microorganisms with widely different architecture and modes of life, namely fungi and viruses. It evaluates to what extent existing models for data treatment of XPS spectra can be applied to understand the chemical composition of their very different surface layers. XPS data from model organisms as well as reference substances representing specific building blocks of their surface were collected and are presented. These results aims to guide future analysis of the surface chemical composition of biological systems.

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Pulping-tailored fiber properties from a novel Brazilian Eucalyptus hybrid

Holzforschung ◽

10.1515/hf-2013-0114 ◽

2014 ◽

Vol 68 (3) ◽

pp. 273-282 ◽

Cited By ~ 1

Author(s):

Marcelo Coelho dos Santos Muguet ◽

Fernando José Borges Gomes ◽

Kyösti Ruuttunen ◽

Leena-Sisko Johansson ◽

Anna-Stiina Jääskeläinen ◽

...

Keyword(s):

Mechanical Properties ◽

Chemical Composition ◽

Photoelectron Spectroscopy ◽

Lignin Content ◽

Eucalyptus Grandis ◽

Physical And Mechanical Properties ◽

Pulp Fibers ◽

Fiber Properties ◽

Thermomechanical Pulping ◽

Bulk Chemical

Abstract The chemical composition and morphology of pulp fibers have a significant impact on the properties of fiber products. Pulp samples from a novel unique Eucalyptus triple hybrid [Eucalyptus grandis × (Eucalyptus urophylla × Eucalyptus globulus)] were obtained by various pulping processes – kraft, soda-anthraquinone (NaOH-AQ), and thermomechanical pulping (TMP). The chemical composition of the fiber surfaces was evaluated by X-ray photoelectron spectroscopy (XPS). The surface lignin content of NaOH-AQ pulp fibers was lower than that of the kraft counterpart. However, kraft pulp handsheets showed better physical and mechanical properties. XPS data strongly suggests that together with the pulp bulk chemical composition the xylan is more abundant on the surface of kraft fibers, which is reflected on their better mechanical properties. Moreover, the relatively low surface lignin content in TMP pulp compared to wood suggests that defibration takes place in the secondary wall, where lignin is less concentrated.

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Surface chemical composition of human maxillary first premolar as assessed by X-ray photoelectron spectroscopy (XPS)

Applied Surface Science ◽

10.1016/j.apsusc.2008.04.085 ◽

2008 ◽

Vol 254 (21) ◽

pp. 6706-6709 ◽

Cited By ~ 12

Author(s):

Leo Lou ◽

Alan E. Nelson ◽

Giseon Heo ◽

Paul W. Major

Keyword(s):

Chemical Composition ◽

Photoelectron Spectroscopy ◽

Surface Chemical ◽

X Ray ◽

Surface Chemical Composition

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Surface Chemical Composition of Size-Fractionated Urban Walkway Aerosols Determined by X-Ray Photoelectron Spectroscopy

Aerosol Science and Technology ◽

10.1080/02786826.2013.824066 ◽

2013 ◽

Vol 47 (10) ◽

pp. 1118-1124 ◽

Cited By ~ 20

Author(s):

Wenjuan Cheng ◽

Lu-Tao Weng ◽

Yongjie Li ◽

Arthur Lau ◽

Chak K. Chan ◽

...

Keyword(s):

Chemical Composition ◽

Photoelectron Spectroscopy ◽

Surface Chemical ◽

X Ray ◽

Surface Chemical Composition

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SYNTHESIS AND DEGRADATION OF THE PbS NANOPARTICLE PHOSPHORS EMBEDDED IN SiO2 (SiO2:PbS)

Surface Review and Letters ◽

10.1142/s0218625x07009955 ◽

2007 ◽

Vol 14 (04) ◽

pp. 697-701 ◽

Cited By ~ 6

Author(s):

M. S. DHLAMINI ◽

J. J. TERBLANS ◽

O. M. NTWAEABORWA ◽

H. C. SWART

Keyword(s):

Chemical Composition ◽

Fiber Optics ◽

Photoelectron Spectroscopy ◽

Energy Dispersive Spectrometer ◽

Sol Gel ◽

High Vacuum ◽

Ultra High Vacuum ◽

Beam Current Density ◽

Surface Chemical ◽

Pbs Nanoparticle

PbS nanoparticle phosphors embedded in SiO 2 were synthesized at room temperature by the sol–gel method. The as-prepared SiO 2:0.134 mol% PbS nanoparticles were ground and annealed in atmosphere. Changes in the cathodoluminescence (CL) brightness and the surface chemical composition of the SiO 2:0.134 mol% PbS nanoparticle powders were investigated using a Fiber Optics PC2000 spectrometer for CL and Auger Electron Spectroscopy (AES) and X-ray Photoelectron Spectroscopy (XPS) for the surface chemical analysis. The chemical composition of the powders was analyzed by an energy-dispersive spectrometer (EDS). The CL intensity decreased when the powders were irradiated with a beam of electrons at 2 keV energy and a beam current density of 54 mA/cm2 in an ultra-high vacuum chamber at oxygen ( O 2) pressures ranging between 5 × 10-8 and 2 × 10-7 Torr for several hours. The O 2 Auger peak-to-peak height (APPH) decreased as the CL intensity decreased. XPS analysis on the degraded spot showed the development of characteristic SiO , SiO x, and elemental Si peaks on the low-energy side of the SiO 2 peak. The desorption of O 2 from the surface, which resulted in a decrease in the CL intensity is attributed to the dissociation of SiO 2 into elemental Si and O 2 by the electron bombardment. The degradation was less severe at higher oxygen pressures. PbSO 4 was also formed on the surface during the electron beam degradation process.

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Bulk and Surface Chemical Composition of Wheat Flour Particles of Different Sizes

Journal of Chemistry ◽

10.1155/2019/5101684 ◽

2019 ◽

Vol 2019 ◽

pp. 1-11 ◽

Cited By ~ 1

Author(s):

Jiangtao Lin ◽

Yujuan Gu ◽

Ke Bian

Keyword(s):

Particle Size ◽

Chemical Composition ◽

Wheat Flour ◽

Independent Effect ◽

Surface Chemical ◽

Bulk Chemical Composition ◽

Surface Chemical Composition ◽

Bulk Chemical ◽

Starch Composition

Chemical composition and particle size are the critical factors influencing the quality and application of flour. The present study investigated the microstructure and distribution of bulk and surface chemical composition in wheat flour particles of different size. Eight samples of wheat flour of different particle size were obtained from the same native wheat flour by sieving (sieve aperture from 25 to 112 μm). Results from scanning electron microscopy and bulk chemical composition analyze showed that flour particles of different sizes differed in microstructure, protein, and starch composition. Further analysis of protein fractions with varying solubility implied that the relative smaller flour particles (diameter <48 μm) had higher gluten protein (gliadin and glutenin) ratio (60.88–64.06%). Furthermore, amino acid analysis showed that glutamic acid was rich in the medium particles. The results of XPS showed that the surface chemical composition of wheat flour of different sizes had no correlation with the bulk chemical composition, indicating that they would have an independent effect on the quality of flour.

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