Giovanni Cerulli, Yingying Dong, Arthur Lewbel and Alexander Poulsen
Regression discontinuity (RD) models are commonly used to nonparametrically identify and estimate a local average treatment effect. Dong and Lewbel (2015) show how a derivative of…
Abstract
Regression discontinuity (RD) models are commonly used to nonparametrically identify and estimate a local average treatment effect. Dong and Lewbel (2015) show how a derivative of this effect, called treatment effect derivative (TED) can be estimated. We argue here that TED should be employed in most RD applications, as a way to assess the stability and hence external validity of RD estimates. Closely related to TED, we define the complier probability derivative (CPD). Just as TED measures stability of the treatment effect, the CPD measures stability of the complier population in fuzzy designs. TED and CPD are numerically trivial to estimate. We provide relevant Stata code, and apply it to some real datasets.
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Nancy Sobh, Nagla Elshemy, Sahar Nassar and Mona Ali
Due to herbs and plants’ therapeutic properties and simplicity of availability in nature, humans have used them to treat a variety of maladies and diseases since ancient times…
Abstract
Purpose
Due to herbs and plants’ therapeutic properties and simplicity of availability in nature, humans have used them to treat a variety of maladies and diseases since ancient times. Later, as technology advanced, these plants and herbs gained significant relevance in some industries due to their suitable chemical composition, abundant availability and ease of access. Aegle marmelos is a species of plant that may be found in nature. Yet, little or very little literature was located on the coloration behavior of this plant’s leaves. This study aims to focus on the effect of different parameters on the extraction of colorant from Aegle marmelos leaves.
Design/methodology/approach
Some factors that affected on the extraction processes were examined and found to have significant impacts on the textile dyeing such as the initial dye concentration, extracted temperature, extracted bath pH and extracted time were all changed to see how they affected color extraction. The authors report a direct comparison between three heating methods, namely, microwave irradiation (MWI), ultrasonic waves (USW) and conventional heating (CH). The two kinetic models have been designed (pseudo-first and pseudo-second orders) in the context of these experiments to investigate the mechanism of the dyeing processes for fabrics under study. Also, the experimental data were analyzed according to the Langmuir and Freundlich isotherms.
Findings
From the result, it was discovered these characteristics were found to have a substantial effect on extraction efficiency. Temperature 90°C and 80°C when using CH and USW, respectively, while at 90% watt when using MWI, period 120 min when using CH as well as USW waves, while 40 min when using MWI, and pH 4, 5 and 10 for polyamide, wool and cotton, respectively, were the optimal extraction conditions. Also, the authors can say that wool gives a higher absorption than the other fabric. Additionally, MWI provided the best color strength (K/S) value, and homogeneity, at low temperatures reducing the energy and time consumed. The coloring follows the order: MWI > USW > CH. The adsorption isotherm of wool could be well fitted by Freundlich isotherm when applying CH and USW as a heating source, while it is well fitted by the Langmuir equation in the case of MWI. In the study, it was observed that the pseudo-first-order kinetic model fits better the experimental results of CH with a constant rate K1 = −0.000171417 mg/g.min, while the pseudo-second-order kinetic model fits better the experimental results of absorption of both MWI (K2 = 38.14022572 mg/g.min) and USW (K2 = 12.45343554 mg/g.min).
Research limitations/implications
There is no research limitation for this work. Dye was extracted from Aegle marmelos leaves by applying three different heating sources (MWI, ultrasonic waves [USWW] and CH).
Practical implications
This work has practical applications for the textile industry. It is concluded that using Aegle marmelose leaves can be a possible alternative to extract dye from natural resource by applying new technology to save energy and time and can make the process greener.
Social implications
Socially, it has a good impact on the ecosystem and global community because the extracted dye does not contain any carcinogenic materials.
Originality/value
The work is original and contains value-added products for the textile industry and other confederate fields.
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K. Haggag, N.S. Elshemy and N.A. Nasef
The dyeing of cotton and cotton/wool blend fabric by using reactive dyes has been studied with both conventional heating and microwave irradiation. The effects of the dye bath pH…
Abstract
The dyeing of cotton and cotton/wool blend fabric by using reactive dyes has been studied with both conventional heating and microwave irradiation. The effects of the dye bath pH, microwave power, dyeing time and dye concentration are studied and the resulting shades obtained by dyeing through microwave and conventional techniques are compared. The results of the dyed samples indicate that microwave irradiation is more effective than conventional heating. Color strength values obtained are found to be higher by microwave irradiation. The results of the fastness properties of the dyed fabric are good to very good. The dyeing kinetics of cotton and cotton/wool blend fabrics are also compared by using the two methods. The values of the dyeing rate constant, half dyeing time (t 1/2), stander affinity and microwave efficiency are calculated and discussed. The physical properties of the samples are studied before and after exposure to microwave irradiation by a scanning electron microscope and an x- ray analysis.
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K. Haggag, H. S. El-Sayad, Sh. Abd El-Moez and I. Abd El-Thalouth
Cellulosic wastes from El-Nasr Co. for Intermediate Chemicals are used as a starting material for the preparation of methylcellulose with tailored properties. The wastes are first…
Abstract
Cellulosic wastes from El-Nasr Co. for Intermediate Chemicals are used as a starting material for the preparation of methylcellulose with tailored properties. The wastes are first purified, followed by alkali ageing for different intervals of time. This is done to control the molecular weight of the cellulose molecules, thereby obtaining cellulosics with different degrees of polymerization (DP). These samples along with the original purified cellulose are methylated under similar conditions and the obtained methylcellulose samples are examined for solubility, degree of substitution (DS) and rheological properties. The results obtained from these investigations are summarized as follows. It is found that the DP of the starting cellulose progressively decreases by prolonging the duration of alkali ageing, while the carboxyl content increases. The DS of the methyl groups increases as the DP of the starting substrate decreases. The rheological properties as well as the apparent viscosity at various rates of shear for the prepared derivatives are thoroughly investigated.
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K. Haggag, N.S. Elshemy and W. Niazy
Modified alkyd resins with different amounts of vegetable oil contents (sunflower oil) and different catalysts are synthesized with the incorporation of post-consumer polyethylene…
Abstract
Modified alkyd resins with different amounts of vegetable oil contents (sunflower oil) and different catalysts are synthesized with the incorporation of post-consumer polyethylene terephthalate (PET) as a partial substitute for phthalic anhydride. It is found that the properties of the products obtained are directly related to the oil content. The polymerization reactions are followed by the acid value. The modified binder contains 50% oil and 10% PET in the presence of LiOH as the catalyst by using microwave irradiation. The AV value is attained in a short amount of time; it is found that the glass Transition Temperature (Tg) of the modified binder is -1.7 °C. The stiffness and roughness of the printed fabrics by using the modified binder are better than those of the commercial binder for both cotton and cotton/polyester fabrics. Moreover, it is clear that the overall fastness properties of the fabrics printed by using the modified binder in the formulation of printing pastes are higher or comparable to those that use commercial binders.
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M.H. Abo-Shosha, F.A. Nassar, K.M. Haggag, Z. El-Sayed and A.G. Hassabo
Condensates of stearic (St), palmitic (Pa) or myristic (My) acids with polyethylene glycols (PEG) 300, 400, 600, 2000 or 6000, are utilized as emulsifiers for kerosene ∓ in �…
Abstract
Condensates of stearic (St), palmitic (Pa) or myristic (My) acids with polyethylene glycols (PEG) 300, 400, 600, 2000 or 6000, are utilized as emulsifiers for kerosene ∓ in ∓ water pigment printing pastes. Pastes based on condensates of PEG 300 or 400 are unstable while the others are stable. Rheology of stable pastes, aside from those based on a commercial emulsifier, are of a non ∓ Newtonian, shear thinning ∓ thixotropic flow. The order of the flow properties of pastes enhanced are found. Cotton pigment prints using the nine pastes are sharp and of comparable handle, colour strength and color fastness to those based on a paste of either a commercial emulsifier or synthetic thickener (except for Pa∓6000). The pigment prints of 65/35 cotton/polyester are sharp only upon using pastes of commercial emulsifier, synthetic thickener, St∓600, St∓2000, St∓6000 and My∓2000. After 7 days of storing, all pastes are stable with increased apparent viscosities and induced color strength on both cotton and blended fabrics.
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The behaviour of chemically modified cellulose towards dyeing is an interesting subject. Cellulose undergoes substantial changes in its chemical and physical properties by…
Abstract
The behaviour of chemically modified cellulose towards dyeing is an interesting subject. Cellulose undergoes substantial changes in its chemical and physical properties by chemical modification. Some investigations were carried out to study the effect of these changes on dyeing and dyeing properties of cellulose. Previous reports have disclosed that the dyeability of chemically modified cellulose differs significantly when compared with the unmodified cellulose. Among the modified cellulose studied were partially acetylated cellulose, cyanoethylated cellulose, carboxymethylated cellulose, cellulose tiaocarbonate and cellulose copolymerized with various vinyl monomers.
This paper aims to study microwave pad dyeing process for wool fabric. Influences of various dyeing process conditions including galactomannan dosage, urea dosage, sodium…
Abstract
Purpose
This paper aims to study microwave pad dyeing process for wool fabric. Influences of various dyeing process conditions including galactomannan dosage, urea dosage, sodium bisulphite dosage, pH value, microwave irradiation power, treating time and cold batching time before microwave fixation on K/S values were analysed. The colour yield, fixation and levelness were compared between microwave fixation and cold batching fixation.
Design/methodology/approach
Colour yield (K/S values) was calculated using a Datacolor SF650 colour measuring and matching instrument (10° standard observer, CIE D65 light source Measuring; Datacolor, USA) and was used to determine the depth of the shade of dyed wool fabrics. Levelness of dyeing was evaluated also using the Datacolor SF650 colour measuring and matching instrument by measuring average deviation (S), range (P) of the maximum and the minimum for lightness (L), chroma (C) and hue (h), and balanced colour difference (ΔE) at 20 specified uniform locations on the wool fabrics. The colour difference was calculated as per the equation
Findings
This study is based on application of microwave technology in the processing of silk.
Originality/value
It was found in laboratory experiments that uniform dyeing and deeper colour can be achieved throughout the microwave pad dyeing process for wool by using galactomannan. The novel process could reduce the dyeing time and the energy consumption of the traditional cold pad-batch dyeing process for wool fabric.
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Amna Siddique, Tanveer Hussain, Waseem Ibrahim, Zulfiqar Ali Raza and Sharjeel Abid
This paper aims to investigate the feasibility of potassium permanganate (KMnO4) as an efficient discharging agent for indigo-dyed denim fabrics and identification of key…
Abstract
Purpose
This paper aims to investigate the feasibility of potassium permanganate (KMnO4) as an efficient discharging agent for indigo-dyed denim fabrics and identification of key variables for its cost-efficient implication.
Design/methodology/approach
Response surface methodology, which is a statistical technique for the optimization of process variables, was used to study the effect of three key variables, i.e. KMnO4 concentration, printing paste pH and reaction time on whiteness and strength of discharged printed fabric. Regression models were developed to predict response variables, i.e whiteness, tensile strength and tear strength of discharge printed denim.
Findings
It was found that some captivating discharge printing effects could be produced using appropriate KMnO4 concentration, printing paste pH and reaction time without any significant loss in the fabric strength.
Practical implications
This study highlights the practical implication of KMnO4 to be used as a safe and effective discharging agent under different conditions and to optimize the parameters using statistical analysis to ensure minimum loss in textile properties. The use of denim has evolved over the decades from a rough and tough workwear to highly fashionable apparel. Various dry and wet processing techniques have been introduced in recent years for the value-addition of denim – discharge printing is one of them. As lab to bulk reproducibility requires some sort of experience and adjustments in main parameters, the practical feasibility on the bulk scale should be adjusted in advance by means of the lab scale experimentation.
Originality/value
The KMnO4 oxidation process is considered eco-friendly because manganese dioxide, which is formed when permanganate is reduced, can be recycled. Thus, the use of KMnO4 can be considered as an eco-friendly safe process for the discharging of indigo dyes.
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Nagla Elshemy, Mona Ali and Reem Nofal
The purpose of this study is to successfully apply ultrasonic waves for the quick extraction of flax seed gum from flaxseed hull or whole seed and compare it to the standard…
Abstract
Purpose
The purpose of this study is to successfully apply ultrasonic waves for the quick extraction of flax seed gum from flaxseed hull or whole seed and compare it to the standard technique of extraction.
Design/methodology/approach
The effect of the heating source, extracted time, temperature and pH of extracted solution on the extraction was studied. The obtained gum is subsequently used for silk screen printing on cotton, linen and viscous fabrics. Rheological properties and viscosity of the printing paste were scrutinized in the current study to get a better insight into this important polysaccharide. The output of this effort aimed to specify the parameters of the processes for printing textiles to serve in women’s fashion clothes by applying innovated handmade combinations of Islamic art motives using a quick and affordable method. Seven designs are executed, and inspiring from them, seven fashion designs of ladies’ clothes were designed virtually by Clo 3D software.
Findings
The result recorded that the new gum has excellent printing properties. In addition, they have better rheological properties, viscosity, chromatic strength and fastness qualities, all of which could help them in commercial production.
Research limitations/implications
Flaxseed and three different fabric types (Cotton, Linen and Viscous) were used.
Practical implications
Synthesis of a new biodegradable thickener from a natural resource, namely, flaxseed, by applying new technology to save time, water and energy.
Originality/value
Synthesis of eco-friendly biodegradable thickener and used in textile printing alternative to the synthetic thickener.