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Manual Printing Methods
Published in Asim Kumar Roy Choudhury, Principles of Textile Printing, 2023
Silk gauze is very resistant to acids and solvents. But it is very sensitive to alkali, so that its use is rather restricted. The silk will swell more or less markedly, or can even be destroyed, when printing with alkaline pastes. This swelling reduces the size of the meshes, so that the color lift-off is uncontrollably reduced; furthermore, the strength of the silk threads is also affected. Swelling and heavy-duty wear were reduced by a special finish. Nevertheless, silk gauze should always be after-treated with diluted acetic acid during cleaning. Silk gauze is more or less heavily stained during printing. Staining with acid dyes can be easily removed with alcohol or weakly soda-alkaline soap solutions as cleaning agents. Several screens are often required when printing borders and edge patterns because these are too heavily stained. Silk gauze is less important nowadays as a result of its poor heavy-duty performance in automatic flat screen printing.
Packed Towers
Published in John J. McKetta, Unit Operations Handbook, 2018
The film flow regime is obtained with crimped wire mcsh, wiregauze. and sheet metal structured packings. For such packings, with a relatively high surfacearea. thegas-liquid contactingarea is in the form of a thin liquid film on the packing surface. With wire mesh and gauze-type packings, even thinner liquid films are possible due to enhanced liquid spreading by capillary action. The film-spray flow regime is thought to be characteristic of random packing. Here, a portion of the contacting liquid flows as a film on the packing and a portion flows as liquid droplets falling from one piece of packing to the next. The fraction of the total liquid flowing as a film increases with increasing vapor flow rate up to the loading point. In distillation applications with random packing, Ihe highest contactingcfficiency isexperi-enced at the packing loading point. Typical height equivalent to a theoretical plate (HETP) values are shown in Fig. 7. These values were obtained in total reflux experiments with the o/p-xylene system at 50 mmHg absolute in a 6-in. diameter column [3].
Introduction
Published in John Roberts, Alan Tovey, Anton Fried, Concrete Masonry Designer's Handbook, 2014
John Roberts, Alan Tovey, Anton Fried
For this test, the mould used for the dropping ball test is filled and the average penetration is determined. The depression left by the ball is filled with mortar and struck off level. The surface of the mortar is then covered with two pieces of white cotton gauze (two circles, 110mm in diameter or two squares of 110mm wide) and eight circles of filter paper are placed on top. Extra thick white filter paper of weight 200g/m2 and 110mm in diameter should be used on top of which a non-porous plate 110 mm in diameter should be placed loaded with a 2Kg weight. After two minutes the weight, filter paper and cotton gauze are removed and the gauze discarded.
Modification of cotton gauze by electrospinning of gelatin and honey biopolymer solution
Published in The Journal of The Textile Institute, 2023
Zahra Bagheri Azizabad, Masoumeh Haghbin Nazarpak, Farzaneh Nayeb Habib
Cotton gauze has been used as an upper layer. To reach out to an underlying layer with desirable characteristics, the electrospinning technique has been used to make nanofibers (Hassiba et al., 2016). The electrospinning technique allows for the creation of interconnected networks that are similar to the native structure of the natural ECM, since they mimic the fibrous ECM and can support neo-tissue growth (Azimi et al., 2020). Nanofibers absorb wound fluids and secretions due to high specific surface area (Günday et al., 2020). Electrospun mat set up appropriate porosity, make a barrier against the entry of bacterial infections, and provide the required permeability during dehydration (Hassiba et al., 2016; Kumbar et al., 2008). Due to simplicity, availability, low cost, reproducibility and, fabrication of similar samples, electrospinning is a widely used technique to produce nanofibers with different average diameters (Rasouli et al., 2019; Xue et al., 2019). A variety of natural and synthetic polymers are used to make electrospun mats (Zahedi et al., 2010). Natural polymers are superior because of their high biocompatibility and low cytotoxicity (Bhatia, 2016; Farokhi et al., 2018).
Properties of materials considered for improvised masks
Published in Aerosol Science and Technology, 2021
Steven N. Rogak, Timothy A. Sipkens, Mark Guan, Hamed Nikookar, Daniela Vargas Figueroa, Jing Wang
The woven fabrics typically had a low-quality factor. Cotton gauze (Q = 56 kPa−1) was the notable exception. However, for a mask with 30 Pa pressure drop at the test conditions, one would need over 100 layers and the weight would be 4.5 kg/m2 or 70 g for a typical mask area of 150 cm2. Thus, while this gauze mask would remove over 80% of 2.8 micron particles, it would have a weight comparable to that of an elastomeric half-face respirator and over 20x higher than weight of a typical disposable face mask. A few other woven fabrics approached Q = 30 kPa−1 (flannel, W4; the wool samples, W14–15; and polyester chiffon, W17); where compiling enough layers to give a 30 Pa resistance, filtration efficiency would be ∼60% at 2.8 microns (cf. Table S1). Woven silk (W9) had a relatively low quality factor (Q ∼ 15 kPa−1), consistent with Zhao et al. (2020) (though that work used a significantly smaller challenge aerosol, which makes direct comparison challenging). It is work noting that some of the other woven fabrics (quilting cotton, W5; polyester satin, W9; silk, W16; and polyester chiffon, W17) had low flow resistance that could be suitable for the non-filtering layers of a composite mask. The polyester peel ply material (used for manufacturing resin reinforced plastics) is included here as an extreme example of a tight weave. It is remarkable here because it had one of the highest pressure drops and the highest particle penetration of any material tested.
Effect of different wick materials on solar still performance – a review
Published in International Journal of Ambient Energy, 2021
A. S. Abdullah, F. A. Essa, Z. M. Omara
Spreading water over the glass cover for the purpose of cooling has a common problem. The water is not distributed homogeneously over the whole glass cover. This leads to ineffective glass temperature decline, which leads to the low performance of the solar still. Suneesh et al. (2016) built an inclined wick still fed from a hot saline water tank, Figure 6. In addition, another modification of cooling the top glass cover was provided. This modification was different from the other glass cooling investigations by using a thin cotton gauze layer over the glass cover to make sure the homogeneity and uniform of water film distribution over the whole glass cover as illustrated from Figure 7. The water used to cool the top glass cover was collected and redirected to the hot saline water tank. This reservoir was used to feed the inclined wick still. This distillation system performance was evaluated with and without the thin layer of cotton gauze. Experimental results revealed quicker start-up and greater distillate for the modified stills than the conventional ones due to the lower thermal inertia of both the regenerative effect and wick materials. The existence of the self-operated hot saline water tank boosted the output distillate through the first night hours. Moreover, results concluded that twenty degrees and 200 ml/min were the best inclination and water flow rate for the wick absorber. Besides, the output distilled water was recorded as 5.6 and 6.3 l/m2 for the modified still without and with the cotton gauze layer. The thermal efficacy reached 68% through the best environmental conditions and recorded 60% as an average.