Crystalline family

However, the preparation of an appropriate crystal can prove to be more difficult than the spectroscopy itself. Naturally, sugars are typically a highly crystalline family. But in order to purify them, contemporary chemists would sooner rely on the more systematic and powerful chromatographic methods than on the uncertain search for the ideal solvent for crystallization. There is also a more fundamental problem in that a conformation in the crystal may not be the... 

STRUCTURE AND FUNCTION OF THE SMALL HEAT SHOCK PROTEIN/a-CRYSTALLIN FAMILY OF MOLECULAR CHAPERONES... 

Kokotailo G T and Meier W M 1980 Pentasil family of high silica crystalline materials The Properties and Appiications ofZeoiites (Speciai Pubiication No. 33) ed R P Townsend (London The Chemical Society)pp 133-9... 

Also in 1972 (6), Carbomdum researchers described a family of aromatic copolyesters which were recognized later to form Hquid crystalline melts. The polymers are based on a bisphenol monomer. In 1976, in a patent assigned to Carbomndum, a hydroxybenzoic acid—terephthaHc acid—bisphenol system, modified and softened with isophthaHc acid, was reported to be melt spinnable to produce fiber. 

Heterogeneous Catalysis. The main discovery of the 1980s was the use of titanium sihcaUte (TS-1) a synthetic zeoHte from the ZSM family containing no aluminum and where some titanium atoms replace siUcon atoms in the crystalline system (Ti/Si = 5%) (33). This zeoHte can be obtained by the hydrolysis of a siUcate and an alkyl titanate in the presence of quaternary ammonium hydroxide followed by heating to 170°C. Mainly studies have been devoted to the stmcture of TS-1 and its behavior toward H2O2 (34). The oxidation properties of the couple H2O2/TS-I have been extensively developed in... 

Another important class of titanates that can be produced by hydrothermal synthesis processes are those in the lead zirconate—lead titanate (PZT) family. These piezoelectric materials are widely used in manufacture of ultrasonic transducers, sensors, and minia ture actuators. The electrical properties of these materials are derived from the formation of a homogeneous soHd solution of the oxide end members. The process consists of preparing a coprecipitated titanium—zirconium hydroxide gel. The gel reacts with lead oxide in water to form crystalline PZT particles having an average size of about 1 ]lni (Eig. 3b). A process has been developed at BatteUe (Columbus, Ohio) to the pilot-scale level (5-kg/h). 

Talc [14807-96-6], a naturally occurring mineral of the general chemical composition Mg2Si40 Q(0H)2, is a crystalline hydrous magnesium siUc ate belonging to the general mineral family of the layered siUcates. Other layered siUcates are kaolin, mica, and pyrophyUite (1). 

Industrial carbon anodes and artificial graphites are not a single material but are rather members of a broad family of essentially pure carbon. Fortunately, artificial graphites can be tailored to vary widely in their strength, density, conductivity, pore structure, and crystalline development. These attributes contribute to their widespread applicability. Specific characteristics are imparted to the fmished product by conti ollmg the selection of precursor materials and the method of processing [19]... 

The key innovations in turning optical waveguides (fibres) into a successful commercial product were made by R.D. Maurer in the research laboratories of the Corning Glass Company in New York State. This company was also responsible for introducing another family of products, crystalline ceramics made from glass precursors - glass-ceramics. The story of this development carries many lessons for... 

Dam, along with Karrar of Zurich, isolated the pure vitamin from alfalfa as a yellow oil. Another form, which was crystalline at room temperature, was soon isolated from fish meal. These two compounds were named vitamins Kj and K2. Vitamin K9 can actually occur as a family of structures with different chain lengths at the C-3 position. 

Phosphorus is the eleventh element in order of abundance in crustal rocks of the earth and it occurs there to the extent of 1120 ppm (cf. H 1520 ppm, Mn 1060 ppm). All its known terrestrial minerals are orthophosphates though the reduced phosphide mineral schrieber-site (Fe,Ni)3P occurs in most iron meteorites. Some 200 crystalline phosphate minerals have been described, but by far the major amount of P occurs in a single mineral family, the apatites, and these are the only ones of industrial importance, the others being rare curiosities. Apatites (p. 523) have the idealized general formula 3Ca3(P04)2.CaX2, that is Caio(P04)6X2, and common members are fluorapatite Ca5(P04)3p, chloroapatite Ca5(P04)3Cl, and hydroxyapatite Ca5(P04)3(0H). In addition, there are vast deposits of amorphous phosphate rock, phosphorite, which approximates in composition to fluoroapatite. " These deposits are widely... 

Since niobates and tantalates belong to the octahedral ferroelectric family, fluorine-oxygen substitution has a particular importance in managing ferroelectric properties. Thus, the variation in the Curie temperature of such compounds with the fluorine-oxygen substitution rate depends strongly on the crystalline network, the ferroelectric type and the mutual orientation of the spontaneous polarization vector, metal displacement direction and covalent bond orientation [47]. Hence, complex tantalum and niobium fluoride compounds seem to have potential also as new materials for modem electronic and optical applications. 

Nylon (Polyamide) PA is a crystalline plastic and the first and largest consumption of the engineering thermoplastic. This family of TPs are tough, slippery, with good electrical properties, but hygroscopic and with dimensional stability lower than most other engineering types. Also offered in reinforced and filled grades as a moderately priced metal replacement. 

The second choice is a simpler solution. According to Sarko and Muggli,66 all 39 observed reflections in the Valonia X-ray pattern are indexable by a two-chain triclinic unit cell with a = 9.41, b =8.15 and c = 10.34 A, a = 90°, 3 = 57.5°, and y = 96.2°. Ramie cellulose, on the other hand, is completely consistent with the two-chain monoclinic unit cell. Also, there are significant differences between their high-resolution solid-state l3C NMR spectra, indicating that Valonia and ramie celluloses, the two most crystalline forms, reflect two distinct families of biosynthesis. On this basis, the Valonia triclinic and the ramie monoclinic forms are classified69 as Ia and Ip, respectively. It has been shown from a systematic analysis of the NMR spectra by these authors, and from electron-dif-... 

New family of TPV having heat and oil resistance based on ACM and polyamide Development of crystalline-amorphous block copolymers (Engage), mettalocene catalyzed TPEs, Polyolefin elastomer (POEs), application research on TPEs Protein-based block-copolymer... 

Copolymerization of ethylene and styrene by the INSITE technology from Dow generates a new family of ethylene-styrene interpolymers. Polymers with up to 50-wt% styrene are semicrystalline. The stress-strain behavior of the low-crystallinity polymers at ambient temperature exhibits elastomeric characteristics with low initial modulus, a gradual increase in the slope of the stress-strain curve at the higher strain and the fast instantaneous recovery [67], Similarly, ethylene-butylene copolymers may also be prepared. 

Plastomer, a nomenclature constructed from the synthesis of the words plastic and elastomer, illustrates a family of polymers, which are softer (lower hexural modulus) than the common engineering thermoplastics such as polyamides (PA), polypropylenes (PP), or polystyrenes (PS). The common, current usage of this term is reshicted by two limitahons. First, plastomers are polyolehns where the inherent crystallinity of a homopolymer of the predominant incorporated monomer (polyethylene or isotactic polypropylene [iPP]) is reduced by the incorporahon of a minority of another monomer (e.g., octene in the case of polyethylene, ethylene for iPP), which leads to amorphous segments along the polymer chain. The minor commoner is selected to distort... 

---