scholarly journals In-depth studies on the modifying effects of natural ageing on the chemical structure of European spruce (Picea abies) and silver fir (Abies alba) woods

2020 ◽  
Vol 66 (1) ◽  
Author(s):  
Amir Ghavidel ◽  
Anna Scheglov ◽  
Volker Karius ◽  
Carsten Mai ◽  
Asghar Tarmian ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Abies Alba ◽  
Crystallinity Index ◽  
Silver Fir ◽  
Historical Building ◽  
X Ray ◽  
Dry Conditions ◽  
Morphological Differences ◽  
Silver Fir Wood ◽  
The One

Abstract Wood is usually stable under relatively dry conditions but may still undergo slow deterioration. The type of deterioration and how these processes affect the wood are important questions that need consideration if old wooden structures are to be studied and properly preserved. The aim of this paper is to establish the main structural and morphological differences between new and naturally aged European spruce (~ 150–200 years) and silver fir wood (~ 150 years). Naturally aged European spruce (a) was sourced from an outdoor part of a building constructed in the seventeenth century and naturally aged European spruce (b) were obtained from a furniture item located in a historical building from the eighteenth century. The principal age-induced changes in fir are the degradation of C–O and C=O groups in hemicellulose, according to the FTIR analysis. Degradation of cellulose and hemicelluloses was observed for spruce, with a greater effect seen in the indoor aged sample. X-ray photoelectron spectroscopy (XPS) showed that after aging C–C/C–H peaks were smaller in the spruce and fir samples, while C–O and O–C–O peaks were larger. The crystallinity index (CrI) obtained by X-ray diffraction showed that due to weathering the CrI of naturally aged spruce (a) increased compared to the new wood. The CrI of the aged spruce (b) and aged fir was lower than in the new woods. The ratios for the spruce sample, which aged indoors, were higher than those for the one aged outdoors. According to the observations made in this study, hemicellulose and cellulose are easily degraded under environmental conditions.

scholarly journals Electrodeposition of Cu–SWCNT Composites

2019 ◽  
Vol 5 (3) ◽  
pp. 38 ◽  
Author(s):  
Pavan M. V. Raja ◽  
Gibran L. Esquenazi ◽  
Cathren E. Gowenlock ◽  
Daniel R. Jones ◽  
Jianhua Li ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Single Walled Carbon Nanotubes ◽  
Controlled Synthesis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fe Catalyst ◽  
Dispersing Agent ◽  
Morphological Differences ◽  
Walled Carbon Nanotubes ◽  
Electrical Conductors

Single walled carbon nanotubes (SWCNTs) are used as a component of a plating solution of CuSO4 for direct current electrodeposition of Cu–SWCNT composites with varying nanotube proportions without the use of either a surfactant, a dispersing agent, or functionalization of the SWCNTs. The Cu–SWCNT composites are characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Raman spectroscopy. The composites are comprised of metallic Cu and SWCNTs with minor oxide impurities, as well as the residual (Fe) catalyst from the unpurified SWCNTs, in addition to displaying nanotube-mediated morphological differences. EDX analysis of carbon (wt%) is close to quantitative with respect to the wt% of SWCNTs added to the electrolysis solution. The presence of SWCNTs decreases the oxidation of the copper, as well as changing the identity of the oxide from CuO, for electrolysis of Cu, to Cu2O. Hard adherent Cu–SWCNT coatings are prepared by the addition of Cu powder to the electrolysis solution. The approach described in this paper will enable controlled synthesis of metal-nanomaterial composites that can potentially be processed further into high ampacity electrical conductors.

scholarly journals EMI Shielding of the Hydrophobic, Flexible, Lightweight Carbonless Nano-Plate Composites

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 2086
Author(s):  
Kanthasamy Raagulan ◽  
Jin Soo Ghim ◽  
Ramanaskanda Braveenth ◽  
Moon Jai Jung ◽  
Sang Bok Lee ◽  
...  
Keyword(s):  
Sheet Resistance ◽  
Photoelectron Spectroscopy ◽  
Cost Effective ◽  
Incident Radiation ◽  
Work Of Adhesion ◽  
Emi Shielding ◽  
Minimum Thickness ◽  
X Ray ◽  
Synthetic Strategy ◽  
The One

The cost-effective spray coated composite was successfully synthesis and characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction techniques. The one step synthetic strategy was used for the synthesis of nanoplates that have a crystalline nature. The composites are amorphous and hydrophobic with micron thickness (<400 μm). The maximum contact angle showed by composite is 132.65° and have wetting energy of −49.32 mN m−1, spreading coefficient −122.12 mN m−1, and work of adhesion 23.48 mN m−1. The minimum thickness of synthesized nanoplate is 3 nm while the maximum sheet resistance, resistivity, and electrical conductivity of the composites are 11.890 ohm sq−1, 0.4399 Ω.cm−1, and 8.967 S.cm−1, respectively. The cobalt nanoplate coated non-woven carbon fabric (CoFC) possesses excellent sheet resistance, hydrophobic nature, and EMI shielding efficiency of 99.99964%. The composite can block above 99.9913% of incident radiation (X band). Hence, the composite can be utilized in application areas such as medical clothes, mobile phones, automobiles, aerospace, and military equipment.

scholarly journals Near-IR Emitting Si Nanocrystals Fabricated by Thermal Annealing of SiNx/Si3N4 Multilayers

2019 ◽  
Vol 9 (22) ◽  
pp. 4725
Author(s):  
D. M. Zhigunov ◽  
A. A. Popov ◽  
Yu. M. Chesnokov ◽  
A. L. Vasiliev ◽  
A. M. Lebedev ◽  
...  
Keyword(s):  
Thermal Annealing ◽  
Photoelectron Spectroscopy ◽  
Annealing Temperature ◽  
X Ray ◽  
Near Ir ◽  
Transmission Electron ◽  
Si Nanocrystals ◽  
Mean Size ◽  
The One ◽  
Multilayered Thin Films

Silicon nanocrystals in silicon nitride matrix are fabricated by thermal annealing of SiNx/Si3N4 multilayered thin films, and characterized by transmission electron microscopy, X-ray reflectivity and diffraction analysis, photoluminescence and X-ray photoelectron spectroscopy techniques. Si nanocrystals with a mean size of about 4 nm are obtained, and their properties are studied as a function of SiNx layer thickness (1.6–2 nm) and annealing temperature (900–1250 °C). The effect of coalescence of adjacent nanocrystals throughout the Si3N4 barrier layers is observed, which results in formation of distinct ellipsoidal-shaped nanocrystals. Complete intermixing of multilayered film accompanied by an increase of nanocrystal mean size for annealing temperature as high as 1250 °C is shown. Near-IR photoluminescence with the peak at around 1.3–1.4 eV is detected and associated with quantum confined excitons in Si nanocrystals: Photoluminescence maximum is red shifted upon an increase of nanocrystal mean size, while the measured decay time is of order of microsecond. The position of photoluminescence peak as compared to the one for Si nanocrystals in SiO2 matrix is discussed.

Characterization of Flax, Jute, and Sisal Fibers after Sodium Perborate Modification

2019 ◽  
Vol 6 (6) ◽  
pp. 25-31
Author(s):  
Yasemin Seki ◽  
Ahmet Çağrı Kılınç ◽  
Ramazan Dalmış ◽  
Serhan Köktaş ◽  
Erdal Çelik
Keyword(s):  
Photoelectron Spectroscopy ◽  
Crystallinity Index ◽  
Hydrophobic Surface ◽  
Surface Characteristics ◽  
Surface Cleaning ◽  
Sodium Perborate ◽  
Sem Images ◽  
X Ray ◽  
Fiber Separation ◽  
Sisal Fibers

The aim of this research is to investigate sodium perborate tetrahydrate (SP) modification of cellulosic fibers. Flax, jute, and sisal fibers were treated with aqueous solutions of SP at three different concentrations. The changes in surface characteristics were analyzed using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). No significant changes in the crystallinity index for all fibers tested were observed as SP treatments only produced surface modification. SEM images showed partial removal of non-cellulosic components occurred. Increased SP concentrations led to greater surface cleaning and fiber separation, imparting a more hydrophobic surface character.

scholarly journals One-Pot Hydrothermal Synthesis, Characterization, and Desulfurization Performance of ZnFe2O4/AC Composites

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Hui-qiang Wang ◽  
Ming-hua Liu ◽  
Xin Luo ◽  
Yi-fan Liu ◽  
Fei-er Chen ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Photoelectron Spectroscopy ◽  
Performance Test ◽  
X Ray Diffraction ◽  
One Pot ◽  
X Ray ◽  
Synthesis Conditions ◽  
Ft Ir ◽  
The One ◽  
Sulfur Adsorption

ZnFe2O4/AC composites were prepared by the one-pot hydrothermal method using the activated carbon (AC) as a carrier. The synthesis conditions were optimized by a single-factor experiment. The structural, textural, and surface properties of the adsorbent have been comprehensively characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, Brunauer–Emmett–Teller (BET) measurements, and X-ray photoelectron spectroscopy (XPS) analysis. The SO2 removal capacities of the composites were investigated via testing the adsorption capacity at the self-made desulfurization equipment. The results show that the adsorption capacity of ZnFe2O4/AC composites is much higher than that of the AC and ZnFe2O4 samples, respectively. The composite overcomes the disadvantages of the traditional sintering, showing a very high desulfurization performance. The breakthrough time was 147 min, and the sulfur adsorption capacity could reach 23.67% in the desulfurization performance test.

The Effect of Different Concentration of Nitrogen in N, S Codoped TiO2

2011 ◽  
Vol 183-185 ◽  
pp. 1791-1794 ◽  
Author(s):  
Yong Bo Lin ◽  
Si Yao Guo ◽  
Feng Fei Wang ◽  
Cheng Hui Zeng ◽  
Na Jiang ◽  
...  
Keyword(s):  
Particle Size ◽  
Calcination Temperature ◽  
Photoelectron Spectroscopy ◽  
Organophosphorus Pesticide ◽  
X Ray Diffraction ◽  
X Ray ◽  
The One ◽  
Anneal Temperature ◽  
Tungsten Lamp

In this paper, the degradation of organophosphorus pesticide by nitrogen and sulfur codoped TiO2 photocatalysts under iodine-tungsten lamp irradiation has been investigated. And we adjusted the concentration of nitrogen to see the change of particle size of nitrogen and sulfur codoping TiO2. According to the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), the different concentration of N, S codoping under different calcination temperature was discussed. N, S codoped TiO2 sample has a smaller particle size at a low anneal temperature than the one at high anneal temperature.

scholarly journals Influence of Tin Doped TiO2 Nanorods on Dye Sensitized Solar Cells

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6282
Author(s):  
Sandeep B. Wategaonkar ◽  
Vinayak G. Parale ◽  
Sawanta S. Mali ◽  
Chang-Kook Hong ◽  
Rani P. Pawar ◽  
...  
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Dye Sensitized Solar Cells ◽  
Rutile Phase ◽  
Tio2 Thin Films ◽  
Doped Tio2 ◽  
X Ray ◽  
Dye Sensitized ◽  
The One ◽  
Energy Conversion Devices

The one-step hydrothermal method was used to synthesize Sn-doped TiO2 (Sn-TiO2) thin films, in which the variation in Sn content ranged from 0 to 7-wt % and, further, its influence on the performance of a dye-sensitized solar cell (DSSC) photoanode was studied. The deposited samples were analyzed by X-ray diffraction (XRD) and Raman spectroscopy, which confirmed the existence of the rutile phase of the synthesized samples with crystallite size ranges in between 20.1 to 22.3 nm. In addition, the bare and Sn-TiO2 thin films showed nanorod morphology. A reduction in the optical band gap from 2.78 to 2.62 eV was observed with increasing Sn content. The X-ray photoelectron spectroscopy (XPS) analysis confirmed Sn4+ was successfully replaced at the Ti4+ site. The 3-wt % Sn-TiO2 based DSSC showed the optimum efficiency of 4.01%, which was superior to 0.87% of bare and other doping concentrations of Sn-TiO2 based DSSCs. The present work reflects Sn-TiO2 as an advancing material with excellent capabilities, which can be used in photovoltaic energy conversion devices.

scholarly journals THE DEGRADATION OF THE PROTECTIVE SCALE ON BINARY FeCr ALLOYS (Fe-2.25Cr, Fe-10Cr, Fe-18Cr AND Fe-25Cr) IN CO2 AND IN CO2 + H2O ENVIRONMENT AT 600oC

2016 ◽  
Vol 39 (1) ◽  
pp. 15-29
Author(s):  
Bagas Pujilaksono
Keyword(s):  
Cross Sections ◽  
Photoelectron Spectroscopy ◽  
Chromium Content ◽  
X Ray Diffraction ◽  
Protective Oxide ◽  
Breakaway Oxidation ◽  
X Ray ◽  
Protective Scale ◽  
Dry Conditions ◽  
Scale Surface

The oxidation behaviour of the binary alloys Fe-2.25, Fe-10Cr, Fe-18Cr and Fe-25Cr in dry and wet O2 at 600oC is investigated by isothermal exposures of carefully polished samples for up to 168 hours. The oxidized samples are investigated gravimetrically and the oxides formed are studied by X-ray diffraction. X-ray photoelectron spectroscopy is used for depth pro􀂿 ling of the thin oxides. The scale surface is imaged by SEM. Cross sections through the scale are analyzed by SEM/EDX for imaging and for measuring the chemical composition. The oxidation behavior of the four FeCr alloys is intermediate between those of iron and chromium. Fe-2.25Cr oxidizes in a way similar to iron in both environments, forming a poorly protective scale consisting of FeCr spinel at the bottom, magnetite in the middle and a hematite cap layer. In dry O2, Fe-10Cr, Fe-18Cr and Fe-25Cr form a thin and protective (Fe,Cr)2O3 oxide similar to the chromia 􀂿 lm formed on pure chromium. In wet O2, Fe-10Cr, Fe-18Cr and Fe-25Cr initially form the same kind of protective oxide 􀂿 lm as in dry conditions. After an incubation time that depends on alloy chromium content, all three alloys go into breakaway oxidation and form thick, poorly protective scales similar to those formed on Fe-2.25Cr. Breakaway oxidation in wet O2 is triggered by the evaporation of CrO2(OH)2 from the protective (Fe,Cr)2O3 oxide.

Blue/White Emission from Hydrogenated Amorphous Silicon Carbide Films Prepared by PECVD

2009 ◽  
Vol 1153 ◽  
Author(s):  
Volodymyr Ivashchenko ◽  
Andrey Vasin ◽  
L. A. Ivashchenko ◽  
P. L. Skrynskyy
Keyword(s):  
Silicon Carbide ◽  
Photoelectron Spectroscopy ◽  
Chemical Vapor ◽  
Substrate Bias ◽  
Double Peak ◽  
Hydrogenated Silicon ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
The One

AbstractPhotoluminescence (PL) from hydrogenated silicon carbide (SiC:H) films is studied at room temperature. The films were deposited by plasma-enhanced chemical vapor (PECVD) technique with and without substrate bias using methyltrichlorosilane as a main precursor. After the deposition the samples were annealed at various temperatures in vacuum. The films were characterized by atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The samples deposited without substrate bias (series A) were amorphous, whereas the samples deposited with negative substrate bias -100V (series B) were nanocrystalline. The one-peak (470 nm) and double-peak (415 and 437 nm) PL structures of the as-deposited samples A and B were observed, respectively. Annealing strongly enhanced intensity of PL of the samples B and trandformed PL spectrum from double-peak into broad featureless band with intensity at about 470 nm. The blue PL in as-deposited films B is supposed to be assigned to the radiative recombination in the sites located at the nanocrystallite surface, whereas the photo excitation of carries mostly occurs in nanocrystallite cores. A further increase in annealing temperature causes hydrogen effusion, which leads to an increase of the concentration of non-raidative recombination centers associated with dangling-bonds and as a result, to the quenching of PL.

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