THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

Keratinous materials such as wool, feathers and hooves are tough unique biological co-products that usually have high sulfur and protein contents A high cystine content (7–13%) differentiates keratins from other structural proteins, such as collagen and elastin Dissolution and extraction of keratin is a difficult process compared to other natural polymers, such as chitosan, starch, collagen, and a large-scale use of keratin depends on employing a relatively fast, cost-effective and time efficient extraction method Keratin has some inherent ability to facilitate cell adhesion, proliferation, and regeneration of the tissue, therefore keratin biomaterials can provide a biocompatible matrix for regrowth and regeneration of the defective tissue Additionally, due to its amino acid constituents, keratin can be tailored and finely tuned to meet the exact requirement of degradation, drug release or incorporation of different hydrophobic or hydrophilic tails This review discusses the various methods available for the dissolution and extraction of keratin with emphasis on their advantages and limitations The impacts of various methods and chemicals used on the structure and the properties of keratin are discussed with the aim of highlighting options available toward commercial keratin production This review also reports the properties of various keratin-based biomaterials and critically examines how these materials are influenced by the keratin extraction procedure, discussing the features that make them effective as biomedical applications, as well as some of the mechanisms of action and physiological roles of keratin Particular attention is given to the practical application of keratin biomaterials, namely addressing the advantages and limitations on the use of keratin films, 3D composite scaffolds and keratin hydrogels for tissue engineering, wound healing, hemostatic and controlled drug release

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Keratin: dissolution, extraction and biomedical application

Nanoparticles are very interesting because of their surface properties, different from bulk materials. Such properties make possible to endow ordinary products with new functionalities. Their relatively low cost with respect to other nano-additives make them a promising choice for industrial mass-production systems. Nanoparticles of different kind of materials such as silver, titania, and zinc oxide have been used in the functionalization of fibers and fabrics achieving significantly improved products with new macroscopic properties. This article reviews the most relevant approaches for incorporating such nanoparticles into synthetic fibers used traditionally in the textile industry allowing to give a solution to traditional problems for textiles such as the microorganism growth onto fibers, flammability, robustness against ultraviolet radiation, and many others. In addition, the incorporation of such nanoparticles into special ultrathin fibers is also analyzed. In this field, electrospinning is a very promising technique that allows the fabrication of ultrathin fiber mats with an extraordinary control of their structure and properties, being an ideal alternative for applications such as wound healing or even functional membranes.

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Nanomaterials for Functional Textiles and Fibers

Smart Polymeric Hydrogels for Cartilage Tissue Engineering: A Review on the Chemistry and Biological Functions

Recently, electrical stimulation as a physical stimulus draws lots of attention. It shows great potential in disease treatment, wound healing, and mechanism study because of significant experimental performance. Electrical stimulation can activate many intracellular signaling pathways, and influence intracellular microenvironment, as a result, affect cell migration, cell proliferation, and cell differentiation. Electrical stimulation is using in tissue engineering as a novel type of tool in regeneration medicine. Besides, with the advantages of biocompatible conductive materials coming into view, the combination of electrical stimulation with suitable tissue engineered scaffolds can well combine the benefits of both and is ideal for the field of regenerative medicine. In this review, we summarize the various materials and latest technologies to deliver electrical stimulation. The influences of electrical stimulation on cell alignment, migration and its underlying mechanisms are discussed. Then the effect of electrical stimulation on cell proliferation and differentiation are also discussed.

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Electrical stimulation as a novel tool for regulating cell behavior in tissue engineering

In this study, the possibility of keratin extraction from wool and feather by an enzymatic treatment along with a reducing agent has been investigated. The effects of different parameters, that is, enzyme loading, type of substrate and surfactant, hydrolysis time, and reducing agent concentration, have been examined in order to optimize the enzymatic hydrolysis. The optimal condition for maximum keratin extraction was attained by making use of 1 g/L sodium dodecyl sulfate (an anionic surfactant) and 2.6% (v/v) protease (Savinase), along with 8.6 and 6.4 g/L sodium hydrogen sulfite (a reducing agent) for wool and feathers, respectively, at liquor to fiber ratio of 25 mL/g for 4 hr. The obtained results indicated higher degradation of wool fiber in comparison with feathers, which might be due to the higher hydrophilic nature of the former. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) patterns revealed that the molecular weights of the extracted proteins from wool and feather were lower than those for the untreated fibers. Scanning electron micrographs showed fibers fibrillation and degradation upon enzymatic treatment. Besides, Fourier-transform infrared (FTIR) spectra indicated no evident changes in the chemical structure of the hydrolyzed fibers. However, wool and feather remainders were mostly composed of α-helix and β-sheets conformations, respectively.

An investigation on keratin extraction from wool and feather waste by enzymatic hydrolysis

Alkali hydrolysis of polyester along with application of nano silver/nano TiO2 to produce hydrolyzed polyester fabric with antibacterial and self-cleaning properties is a very interesting subject. In this article, a novel idea is introduced to achieve a polyester fabric with self-cleaning and antibacterial properties with a good feeling handle in one step. The polyester fabric is hydrolyzed in alkali media to enhance the surface activity, improve nanoparticle absorption, and produce ethylene glycol for reducing silver nitrate into nano silver. XRD pattern confirms the presence of nanoparticles with crystal size of 10 nm on the fabric surface and FESEM pictures show the distribution of nanocomposite particles on the fiber surfaces with average size of 54 nm. The degradation of Methylene Blue under daylight irradiation confirms the photoactivity of nano TiO2 on the polyester fabric. Also, very good bactericidal efficiency is obtained against S. aureus and E. coli. Interestingly, the fabric tensile strength improves even with the action of alkali in surface hydrolysis of polyester. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

In situ synthesis of nano silver on polyester using NaOH/Nano TiO2

Optimization of enzymatic hydrolysis of wool fibers for nanoparticles production using response surface methodology

In this study, chitosan and pentasodium tripolyphosphate (TPP)-based bilayers were fabricated on the cationized woven cotton fabrics via layer-by-layer (LBL) self-assembly technique. The initial cationic charges on cotton fabric were produced through the aminization procedure involving the covalent attachment of reactive dye to cotton fabric and subsequent reductive cleavage of the dye to free amine. Different numbers of bilayers (1, 5, and 10) consisting of chitosan/TPP have been deposited on the fabrics. The surface morphology, cationic group content, chemical surface modification, whiteness index, surface tension and antibacterial properties of the modified cotton samples were investigated using scanning electron microscopy (SEM), methylene blue test, FTIR, reflectance spectroscopy, water contact angle measurements and antibacterial test, respectively. The bacterial inhibition experiments demonstrated that the modified cotton fabric with the addition of chitosan/TPP bilayers can increase the degree of inhibition on E. coli and S. aureus bacteria. The utilized LBL method was an easy and cost-effective procedure for developing of novel antibacterial textiles with the highly attractive feature in the medical and hygienic products.

Nahid Hemmati Nejad

Papers

An investigation on keratin extraction from wool and feather waste by enzymatic hydrolysis

In situ synthesis of nano silver on polyester using NaOH/Nano TiO2

Optimization of enzymatic hydrolysis of wool fibers for nanoparticles production using response surface methodology

Antibacterial finishing of cotton fabric via the chitosan/TPP self-assembled nano layers

Electrical stimulation of somatic human stem cells mediated by composite containing conductive nanofibers for ligament regeneration