Dislocation etching of tin iodide single crystals

Single crystals of tin-iodide (SnI₂) have been grown using the controlled reaction between SnCl₂ and KI by diffusion process in gel medium. As grown (010) surfaces of the crystals have been optically studied. Characteristic etch pits have been observed on them. This suggests that SnI₂ crystals might go into dissolution in the acid-set gel. By successively etching (010) surfaces in a mixture of ammonia, acetic acid, and CdCl₂ solution, it is established that the pits indicate the site of dislocations in the crystals. This is further confirmed by comparing the etch patterns before and after chemically polishing (010) surfaces. The average dislocation density in the crystals have been evaluated and found to be 3.2 × 10³ cm⁻² and the implications are discussed.     

Phenylarsenic(III) complexes of 2-(2-hydroxyphenyl)benzothiazolines

Equimolar reactions of PhAs(OMe)₂ (prepared in situ) and 2-(2-hydroxyphenyl)benzothiazolines LH₂ give the addition products PhAs(OMe)₂LH₂, while equimolar reactions of PhAsCl₂ with Na₂L yield substitution products PhAsL. All these derivatives have been characterized by elemental analyses and their plausible structures have been established on the basis of physico-chemical, IR, and NMR (¹H and ¹³C) spectral studies. © 2003 Wiley Periodicals, Inc. 15:92–96, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/.10220     

Toxicological Effects of Metal Nanoparticles Employed in Biomedicine: Biocompatibility,Clinical Trials,and Future Perspective

Metal nanoparticles play a crucial role in the medical industry due to its desirable properties such as antimicrobial activity, anti-cancer property, and its application in disease diagnostics. These properties enable the nanoparticles to be used as efficient medical devices for various treatments as well as drug delivery systems. Despite all the positives, metal nanoparticles are known for causing toxicity in the living system. The toxicological effects of metal nanoparticles are due to their size, surface*e coating, and the dose administered. Therefore, it is important to study the toxic effects of these nanoparticles before they are used as medical devices for various treatments. This review focuses on the five major metal nanoparticles used in the medical field, namely; silver, gold, iron oxide, zinc oxide, and titanium dioxide nanoparticles. The non-exhaustive review consists of an introduction to the toxicological effects of these nanoparticles, the biocompatibility, and the current and future clinical perspective on metal nanoparticles.     

Structure – Directing Effect of Renewable Resource Based Amphiphilic Dopants on the Formation of Conducting Polyaniline-Clay Nanocomposite

Summary: The structure-directing effect of two amphiphilic dopants on the nucleation and growth mechanism during the formation of micro/ nanostructured polyaniline (PANI) and polyaniline-clay nanocomposites (PANICNs) is described. PANIs and PANICNs were prepared by in-situ intercalative emulsion polymerization of aniline using the amphiphilic dopants, 3-pentadecyl phenyl phosphoric acid (3-PDPPA) and 3-pentadecyl phenol–4-sulphonic acid (3-PDPSA), derived from cashew nut shell liquid, a renewable resource. These molecules act as intercalating agents, dopants and also as structure-directing agents. X- ray diffraction (XRD) and scanning electron microscopic (SEM) studies revealed the formation of lamellar/fibrillar – network in PANI- PDPPA and cylinder/rod morphology in PANI-PDPSA. Experimental data reveal that fibrillar morphology arises from the heterogeneous nucleation followed by an indefinite growth mechanism. On the other hand rod-like structures are formed from the self-assembled rod-like micelle guided polymerization through homonucleation followed by an anisotropic growth mechanism. Electrical conductivity measurement revealed lower conductivities for PANICNs than that of PANIs.     

Microstructures on {111} faces of stannic iodide single crystals

Single crystals of stannic iodide (SnI₄) havebeen grown using the controlled reaction between SnCl₂ and KI by diffusion process in silica gel medium. Orange to reddish octahedral stannic iodide crystals up to 3–4 mm in size have been grown at room temperature. Optical studies have been made on the various surface structures of {111} faces of the asgrown crystals. On octahedral faces of these crystals, triangular-shaped hillocks with growth layers in the 〈110〉 directions have been observed. Occasionally, growth spirals on octahedral faces have also been reported. Close loops of growth fronts have been investigated and have been interpreted. It has been suggested that two-diemensional nucleation, spreading and pilling up of triangular growth layers is mainly responsible for the growth and occasionally the growth is due to screw dislocations. The implications are discussed.     

Microstructures of Tin Iodide Single Crystals Grown in Silica Gels

Single crystals of tin iodide (SnI₂) have been grown in silica gels. A detailed microtopographical study of {100} faces have been described. Horizontal striations are predominant on these faces for most of the crystals, while few of them show vertical striations. The horizontal striations are associated with the two-dimensional nucleation theory whereas the vertical striations relate to the growth fronts. Growth layers modified by the presence of misaligned microcystals have been illustrated. The natural etch pits on {100} faces of the crystal are attributed to the dissolution of crystals in the acid set gel. In the light of these observations, the mechanism of the development and growth of these faces have been assessed and the implications are discussed.     

Some Physicochemical Studies on Binary Organic Eutectics and 1:2 Molecular Complexes

Benzidine-m. aminophenol system gives a double simple eutectic type phase-diagram showing the formation of a 1:2 addition compound with congruent melting point surrounded by two eutectics on either side. The linear velocity of crystallization data on pure components, eutectics, and addition compound suggest square relationship between growth velocity and undercooling. From the X-ray diffraction studies it can be inferred that the eutectics are not a simple mechanical mixtures of two components. Whereas microstructural investigations suggest faceted growth of the addition compound and a typical characteristic growth of the eutectics, spectral studies indicate the formation of intermolecular hydrogen bonding between two components forming the molecular complex.