Red light illumination with photon energy matching the direct band gap of chemical vapor deposition grown single-layer MoS2 with Au metal electrodes was used to induce a photocurrent which was ...employed instead of dark current for NO2 gas sensing. The resulting Au/MoS2/Au optoelectronic gas sensor showed a significant enhancement of the device sensitivity S toward ppb level of NO2 gas exposure reaching S = 4.9%/ppb (4900%/ppm), where S is a slope of dependence of relative change of the sensor resistance on NO2 concentration. Further optimization of the MoS2-based optoelectronic gas sensor by using graphene (Gr) with a work function lower than that of Au for the electrical contacts to the MoS2 channel allowed an increase of photocurrent. The limit of detection of NO2 gas at the level of 0.1 ppb was obtained for the MoS2 channel with graphene electrodes coated by Au. This value was calculated using experimentally obtained sensitivity and noise values and exceeds the U.S. Environment Protection Agency requirement for NO2 gas detection at ppb level.
Textile and fibre chemistry form the theoretical basis to understand production and properties of textile based products. In this 2nd edition fundamentals of textile chemistry and theoretical and ...applicatory aspects of colour chemistry are interconnected to draw detailed picture of chemical reactions occurring during production and modification of textile products. An overview about chemical modification, finishing operations is given to explain how to impart special functionalities into functional products. Examples for technical scale processes and representative machinery used therein give insight into the technical reality of a dyehouse. A new chapter about circularity of textiles highlights the interlinkage between product design, including dyes and finishes, and the requirements to develop future fibre-to-fibre recycling. The work covers all relevant aspects of a textile product from fibre production, coloration, finishing, consumer use and fibre-to-fibre recycling. The content of the book allows a first entry into this multi-disciplinary field. Through its comprehensive character the authors explain the interdependence between textile and fibre processing and aspects of recycling, which makes the work a valuable source of information to design future textiles for circularity.
Natural fibre reinforced plant structures are widely used in nature. These plant structures combine light weight with superior mechanical properties. The fibre orientations in plants are optimized to ...the occurring forces, especially to the bending of plants by wind forces. Therefore it is important to study the effect of fibre orientation to the mechanical properties of materials in a systematic experimental approach. In this study the effect of reinforcement fibre orientation on mechanical properties of bio-based lyocell-reinforced polypropylene composite was analysed. For this purpose, special technique to produce composites with defined fibre orientation and fibre wetting was developed consisting of the production of intermingled hybrid yarn followed by defined yarn laying and thermoforming processes. The formed composites were subjected to tensile strength tests and dynamic mechanical analyses. The experimentally determined E-modulus was compared with values, calculated from the modified rule of mixture of Virk and Krenchel. The analysis showed that the experimental E-moduli were somewhat smaller than the theoretical values, which is indicative of a less than perfect interfacial bonding between the fibres and matrix. The influence of water on the composite performance was also analysed. It was shown that the composites sorb approximately 30% water by weight, and it has a strong influence on the E-modulus and other performance parameters.
Graphical abstract
High performance polymer fibers, such as polyester, aliphatic and aromatic polyamides, are well established in several technical applications, including personal protection equipment, sport, ...automotive or aerospace. This is due to their excellent thermal, mechanical and chemical properties. In the emerging field of textile based high performance composites and intelligent textiles, polymer fibers are often utilized in hybrids, i.e., in combination with other materials such as polymer matrices or metal coatings. In such cases, the step of activating or functionalizing the fibers is essential to enhance interface strength in the hybrid systems.
This review provides a broad overview on recently applied activation and functionalization techniques on high performance polymer fibers including wet chemical and physicochemical treatments (e.g., hydrolysis, oxidation, complexation, deposition, flame, plasma treatment). The main objective is to review possible modification mechanisms, elaborate the effect of the modification on the fiber properties, and address possible applications of these techniques. The review also includes a comparison of the different techniques, thereby providing a better understanding of their potentials and restrictions. While the techniques differ in terms of versatility, handling, and environmental impact they all can, given the right choice of process parameters, provide well-defined fiber surface properties for the intended application.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Aniline and N-methylaniline are common contaminants in commercially produced indigo. It is known, that commercially produced indigo contains up to 0.6% aniline and 0.4% N-methylaniline by weight and ...indigo dye shows a small mutagenic effect, most probably due to the presence of these contaminants. The present work describes a new and powerful analytical method to determine the concentration of these contaminants in indigo. This method is based on the transformation of water insoluble indigo into soluble leucoindigo and allows therefore the acidic extraction of the aromatic contaminants. This transformation step is essential, because the main part of these contaminants are strongly included in the indigo crystals. The amount of extracted aniline and N-methylaniline from the leucoindigo solution was quantified with high performance liquid chromatography (HPLC, combined with a photo diode array detector). A possible accumulation of the aromatic amines at the indigo crystal surface was investigated using FTIR and by adsorption studies. Therefore this method allows an accurate monitoring of these toxic by-products in the indigo dye, which is important for an economic and environmental assessment of the denim production.
The paper is a review on the extraction processes of cellulosic fibers from flax and hemp. The two lignocellulosic crops have a long history of use by humans for extraction of the bast fibers among ...other purposes. The utility of bast fibers declined over time with industrial advances and changes to the economy, but of late, with an increase of focus on environmental impact and sustainability, there is a renewed interest in these resources. The use of biomass-based resource requires an appreciation of plant anatomy and the agronomical variables in their cultivation and harvesting. This review provides an overview of these aspects as well as of the processes of retting for initial weakening of the plant structure in preparation for fiber extraction, degumming to isolate fiber bundles, and delignification.
Control of Axially Moving Systems: A Review Hong, Keum-Shik; Pham, Phuong-Tung
International journal of control, automation, and systems,
12/2019, Letnik:
17, Številka:
12
Journal Article
This paper presents a comprehensive review of significant works on active vibration control of axially moving systems. Owing to their broad applications, vibration suppression techniques for these ...systems have generated active research over decades. Mathematical equations for five different models (i.e., string, beam, coupled, plate, and approximated model) are outlined. Active vibration control of axially moving systems can be performed based on a finite-dimensional model described by ordinary differential equations (ODEs) or an infinite-dimensional model described by partial differential equations (PDEs). For ODE models, the sliding mode control is most representative. For PDE models, however, there exist various methods, including wave cancellation, Lyapunov method, adaptive control, and hybrid control. Control applications (lifting systems, steel industry, flexible electronics, and roll-to-roll systems) are also illustrated. Finally, several issues for future research in vibration control of axially moving systems are discussed.
We show that, in the functional data context, by appropriately exploiting the functional nature of the data, it is possible to cluster the observations asymptotically perfectly.We demonstrate that ...this level of performance can sometimes be achieved by the k-means algorithm as long as the data are projected on a carefully chosen finite dimensional space. In general, the notion of an ideal cluster is not clearly defined.We derive our results in the setting where the data come from two populations whose distributions differ at least in terms of means, and where an ideal cluster corresponds to one of these two populations. We propose an iterative algorithm to choose the projection functions in a way that optimizes clustering performance, where, to avoid peculiar solutions, we use a weighted least squares criterion. We apply our iterative clustering procedure on simulated and real data, where we show that it works well.
During the reprocessing of spent nuclear fuel rods, a highly moist off-gas mixture containing various volatile radioactive species, such as iodine (I
2
), organic iodides and nitric acid, is ...produced. Efforts have been made to devise materials, which can effectively capture radioactive iodine (I
2
) and organic iodides from the off-gas mixture without being damaged by moisture, nitric acid, and I
2
. In the investigation described herein, we observed that all-silica zeolites, such as silicalite-1 and Si-BEA, are stable in 5 M nitric acid and adsorb I
2
, CH
3
I, and CH
3
CH
2
I from highly acidic off-gas mixture to much greater extents than activated carbon does. In particular, the hydrophobicity-intensified silicalite-1 performs best. We further found that I
2
forms a unique semiconducting three-dimensional supramolecular network within the silicalite-1 channels. The conductivity of the fully I
2
loaded silicalite-1 is observed to be
ca.
10
4
S m
−1
, which is
ca.
10
8
-fold higher than that of solid I
2
.
During the reprocessing of spent nuclear fuel rods, a highly moist off-gas mixture containing various volatile radioactive species, such as iodine (I
2
), organic iodides and nitric acid, is produced.
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•The V-doped MnO2 was prepared by a simple ambient redox reaction.•The V-doped MnO2 was tested as a cathode in aqueous zinc-ion batteries (ZIBs).•The doped cathode showed better ...zinc-storage properties than the bare cathode.•The present study facilitates the development of safe and reliable aqueous ZIBs.
In this work, we demonstrate the first use of a V-doped MnO2 nanoparticle electrode for zinc-ion battery (ZIB) applications. The V-doped MnO2 was prepared via a simple redox reaction and the X-ray diffraction studies confirmed the formation of pure MnO2, accompanied by an anisotropic expansion of MnO2 lattice, suggesting the incorporation of V-ions into the MnO2 framework. V doping of MnO2 not only increased the specific surface area but also improved the electronic conductivity. When Zn-storage properties were tested, the V-doped MnO2 electrode registered a higher discharge capacity of 266mAhg−1 compared to 213mAhg−1 for the pure MnO2 electrode. On prolonged cycling, the doped electrode retained 31% higher capacity than that of the bare MnO2 electrode and thereby demonstrated superior cycling performance. This study may pave the way towards understanding the enhancement of the energy storage properties via doping in electrodes of aqueous ZIB applications and also furthers the efforts for the practical realization of a potential eco-friendly battery system.
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