In this chapter, we will restrict our attention to the ferrites and a few other closely related materials. The great interest in ferrites stems from their unique combination of a spontaneous magnetization and a high electrical resistivity. The observed magnetization results from the difference in the magnetizations of two non-equivalent sub-lattices of the magnetic ions in the crystal structure. Materials of this type should strictly be designated as “ferrimagnetic” and in some respects are more closely related to anti-ferromagnetic substances than they are to ferromagnetics in which the magnetization results from the parallel alignment of all the magnetic moments present. We shall not adhere to this special nomenclature except to emphasize effects, which are due to the existence of the sub-lattices.

Ferromagnetic materials

There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate

Handbook of Chemistry and Physics

Electrospinning is a versatile and viable technique for generating ultrathin fibers. Remarkable progress has been made with regard to the development of electrospinning methods and engineering of electrospun nanofibers to suit or enable various applications. We aim to provide a comprehensive overview of electrospinning, including the principle, methods, materials, and applications. We begin with a brief introduction to the early history of electrospinning, followed by discussion of its principle and typical apparatus. We then discuss its renaissance over the past two decades as a powerful technology for the production of nanofibers with diversified compositions, structures, and properties. Afterward, we discuss the applications of electrospun nanofibers, including their use as "smart" mats, filtration membranes, catalytic supports, energy harvesting/conversion/storage components, and photonic and electronic devices, as well as biomedical scaffolds. We highlight the most relevant and recent advances related to the applications of electrospun nanofibers by focusing on the most representative examples. We also offer perspectives on the challenges, opportunities, and new directions for future development. At the end, we discuss approaches to the scale-up production of electrospun nanofibers and briefly discuss various types of commercial products based on electrospun nanofibers that have found widespread use in our everyday life.

Electrospinning and Electrospun Nanofibers: Methods, Materials, and Applications

In this article, several applications of nanomaterials in food packaging and food safety are reviewed, including: polymer/clay nanocomposites as high barrier packaging materials, silver nanoparticles as potent antimicrobial agents, and nanosensors and nanomaterial-based assays for the detection of food-relevant analytes (gasses, small organic molecules and food-borne pathogens). In addition to covering the technical aspects of these topics, the current commercial status and understanding of health implications of these technologies are also discussed. These applications were chosen because they do not involve direct addition of nanoparticles to consumed foods, and thus are more likely to be marketed to the public in the short term.

Applications of nanotechnology in food packaging and food safety: Barrier materials, antimicrobials and sensors

Polymer nanoparticles: Preparation techniques and size-control parameters

Pot experiments were conducted to evaluate the possible roles of nitrogen fixation and/or enhanced mineral uptake by Azospirillum lipoferum and Bacillus polymexa inoculation in improving salt tolerance of maize plants. Plants were inoculated and grown under salt stress (osmotic potential: -0.3, -0.6, -0.9 and -1.2 Mpa). Both microorganisms were able to fix nitrogen up to -0.9 Mpa salinity level accompanied with increased total N-yield compared with the control plants. In order to investigate the role of bacterial inoculation on enhanced mineral uptake, the growth and some physiological parameters of inoculated plants were compared with plants fertilized by K and P foliar application. Plant inoculation with the N2-fixers or plant spraying with KH2PO4 resulted in an increase in fresh and dry matter as well as water content of plants. Treated plants exhibited changed plant mineral content which was associated with increased Mg/K and decreased P/K, Ca/K and Na/K ratios. This was accompanied by accumulation of soluble sugars, amino acids in shoots and roots of plants resulting in a concomitant increase in the osmotic potential of the cell sap as a possible mechanism of adaptation to salinity.

Possible roles of nitrogen fixation and mineral uptake induced by rhizobacterial inoculation on salt tolerance of maize

The Effect of Trace Elements in Cotton Fibres on Their Physical Properties

Cytogenetical and ecological studies in some species of the Solanaceae were made in the Mediterranean-type ecosystem in Upper Egypt. The chromosome complement of Datura innoxia (2n=24) consisted of 24 median-centromeric chromosomes; that of D. stramonium (2n=24) consisted of 22 median- and two submedian-centromeric chromosomes; that of Hyoscyamus albus (2n=68) consisted of 62 median- and six submedian-centromeric chromosomes, that of H. muticus (2n=28) consisted of 21 median- and seven submedian-centromeric chromosomes; that of Withania somnifera (2n=36; new count) consisted of 27 median- and nine submedian-centromeric chromosomes; and that of Solanum nigrum (2n=72) consists of 68 median and four submedian-centromeric chromosomes. Thirty-three reproducible polymorphic bands were resulted after four RAPD-PCR primers; those bands were used for studying the genetics similarity among the species. Average similarity coefficient was ranged from 0.05 to 0.47. RAPD bands resulted after PCR: D. innoxia and D. stramonium showed five bands each; H. albus and H. muticus showed two and one bands respectively; W. somnifera seven bands and S. nigrum showed 13 bands, different patterns were produced among congeneric species. Ionic status of hot water extract of the species revealed that Hyoscyamus species was more accumulated Na+ and Ca++, while Datura species accumulated more K+ and Mg++ and W. somnifera and S nigrum were intermediate. These strategies of ionic accumulation were in relation to the different chromosome number of species, which might help for surviving the species in desert ecosystem.

Cytogenetical and ecological studies of some wild congeneric species in the Solanaceae distributed in upper Egypt

The possibility of using rainwater as a sustainable anolyte in an air-cathode microbial fuel cell (MFC) is investigated in this study. The results indicate that the proposed MFC can work within a w...

https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.210996

Rainwater-driven microbial fuel cells for power generation in remote areas

Nanofibrous morphology and the doping technique can overcome the problem of electron/hole fast recombination and improve the activity of titanium oxide-based photocatalysts. In this study, nanoparticulate and nanofibrous forms of CdTiO3-incorporated TiO2 were synthesized with different cadmium contents; the morphology and composition were determined by SEM, TEM, EDX, and XRD techniques. The nanomorphology, cadmium content, and reaction temperature of Cd-doped TiO2 nanostructures were found to be strongly affect the hydrogen production rate. Nanofibrous morphology improves the rate of hydrogen evolution by around 10 folds over the rate for nanoparticles due to electron confinement in 0D nanostructures. The average rates of hydrogen production for samples of 0.5 wt.% Cd are 0.7 and 16.5 ml/gcat.min for nanoparticles and nanofibers, respectively. On the other hand, cadmium doping resulted in increasing the hydrogen production rate from 9.6 to 19.7 ml/gcat.min for pristine and Cd-doped (2 wt%) TiO2 nanofibers, respectively. May be the formation of type I heterostructures between the TiO2 matrix and CdTiO3 nanoparticles is the main reason for the observed enhancement of photocatalytic activity due to the strong suppressing of electron/holes recombination process. Consequently, the proposed photocatalyst could be exploited to produce hydrogen from scavenger-free solution. Varying reaction temperature suggests that hydrogen evolution over the proposed catalyst is incompatible with the Arrhenius equation. In particular, reaction temperature was found to have a negative influence on photocatalytic activity. This work shows the prospects for using CdTiO3 as a co-catalyst in photon-induced water splitting and indicates a substantial enhancement in the rate of hydrogen production upon using the proposed photocatalyst in nanofibrous morphology.

/pdf/cdtio3-nps-incorporated-tio2-nanostructure-photocatalyst-for-20vef9ol.pdf

Nasser A.M. Barakat

Papers

Possible roles of nitrogen fixation and mineral uptake induced by rhizobacterial inoculation on salt tolerance of maize

The Effect of Trace Elements in Cotton Fibres on Their Physical Properties

Cytogenetical and ecological studies of some wild congeneric species in the Solanaceae distributed in upper Egypt

Rainwater-driven microbial fuel cells for power generation in remote areas

CdTiO3-NPs incorporated TiO2 nanostructure photocatalyst for scavenger-free water splitting under visible radiation