Effects of Introduction of Initial Nuclei on Physical Properties of (Pb,La)(Zr,Ti)O 3 Films Crystallized from Amorphous State

2002 ◽  
Vol 271 (1) ◽  
pp. 199-204 ◽  
Author(s):  
Masafumi Kobune ◽  
Osamu Matsuura ◽  
Tomoaki Matsuzaki ◽  
Tatsuya Sawada ◽  
Hironori Fujisawa ◽  
...  
Keyword(s):  
Physical Properties ◽  
Amorphous State

Synthetic amorphous calcium phosphates (ACPs):preparation, structure, properties and biomedical applications

2021 ◽  
Author(s):  
Sergey V Dorozhkin
Keyword(s):  
Physical Properties ◽  
Biomedical Applications ◽  
Calcium Phosphates ◽  
Amorphous State ◽  
Calcium Orthophosphates ◽  
Structure Properties

Amorphous calcium phosphates (ACPs) represent a metastable amorphous state of other calcium orthophosphates (abbreviated as CaPO4) possessing variable compositional but rather identical glass-like physical properties, in which there are neither...

scholarly journals Extended Release of Timolol from Ethyl Cellulose Microparticles Laden Hydrogel Contact Lenses

2015 ◽  
Vol 2 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Furqan A. Maulvi ◽  
Tejal G. Soni ◽  
Dinesh O. Shah
Keyword(s):  
Physical Properties ◽  
Ethyl Cellulose ◽  
Contact Lenses ◽  
Drug Loading ◽  
Amorphous State ◽  
Eye Drops ◽  
Hydrogel Microparticles ◽  
Zero Order Kinetics ◽  
The Impact

Glaucoma is a second leading cause of blindness globally after cataract, which is managed through eye drops, which are highly inefficient due to a low bioavailability of less than 1-5%. Frequent administration of eye drops leads to incompliance in patients, so there is a great need for medical device such as contact lenses to treat glaucoma. The objective of research was to provide sustained ocular delivery of timolol via prototype poly (hydroxyethyl methacrylate) hydrogel contact lenses which may improve bioavailability due to increase in ocular residence time of drug. The present work was to encapsulate drug in ethylcellulose microparticles, and to entrap these microparticles in the hydrogel. Microparticles were prepared by spray drying method using different ratios of drug to ethylcellulose. The solid state characterization studies of drug loaded microparticles revealed the transformation of drug to an amorphous state. The hydrogels were characterized by studying their optical and physical properties to determine their suitability as extended wear contact lenses. Microparticles laden hydrogels were compared with direct drug loaded hydrogels. The study of microparticles laden hydrogels showed reduction in optical and physical properties and the impact was proportional to the amount of microparticles in hydrogels. The results suggest the application of optimization and nanotechnology. In vitro drug release study revealed that direct loading batch delivers drug for 22 hours with high drug loading of 150 µg, while microparticles laden hydrogel deliver drug up to 48 hours (zero order kinetics) with low drug loading of 50 µg. The hydrogels appeared safe in the cytotoxicity study. The study demonstrated the promising potential of loading the ethyl cellulose microparticles into hydrogels to serve as a good platform for sustained ophthalmic drug delivery.

Polysiloxanes and Related Polymers

2005 ◽  
Author(s):  
James E. Mark ◽  
Harry R. Allcock ◽  
Robert West
Keyword(s):  
Physical Properties ◽  
High Performance ◽  
Amorphous State ◽  
Structural Features ◽  
Inorganic Polymers ◽  
Trans Form ◽  
Synthesis Properties ◽  
Temperature Application ◽  
Siloxane Polymers ◽  
Commercial Applications

At the present time, polysiloxanes are unique among inorganic and semi-inorganic polymers. They have been the most studied by far, and are the most important with regard to commercial applications. Thus, it is not surprising that a large number of review articles exist describing the synthesis, properties, and applications of these materials. The Si-O backbone of this class of polymers endows it with a variety of intriguing properties. For example, the strength of this bond gives the siloxane polymers considerable thermal stability, which is very important for their use in high-temperature application (for example as heat-transfer agents and high-performance elastomers). The nature of the bonding and the chemical characteristics of typical side groups give the chains a very low surface free energy and, therefore, highly unusual and desirable surface properties. Not surprising, polysiloxanes are much used, for example, as mold-release agents, for waterproofing garments, and as biomedical materials. Some unusual structural features of the chains give rise to physical properties that are also of considerable scientific interest. For example, the substituted Si atom and the unsubstituted O atom differ greatly in size, giving the chain a very irregular cross section. This influences the way the chains pack in the bulk, amorphous state, which, in turn, gives the chains very unusual equation-of-state properties (such as compressibilities). Also, the bond angles around the O atom are much larger than those around the Si, and this makes the planar all-trans form of the chain approximate a series of closed polygons. As a result, siloxane chains exhibit a number of interesting configurational characteristics. These structural features, and a number of properties and their associated applications, will be discussed in this chapter. The major categories of homopolymers and copolymers to be discussed are linear siloxane polymers [-SiRR'O-] (with various alkyl and aryl R,R' side groups), (ii) sesquisiloxane polymers possibly having a ladder structure, (iii) siloxane-silarylene polymers [-Si(CH3)2OSi(CH3)2(C6H4)m-] (where the skeletal phenylene units are either meta or para), (iv) silalkylene polymers [-Si(CH3)2(CH2)m-], and (v) random and block copolymers, and blends of some of the above. Topics of particular importance are the structure, flexibility, transition temperatures, permeability, and other physical properties.

Physical Properties of Ternary Re-Fe Base Alloys and their Relationship to Permanent Magnet Applications

1987 ◽  
Vol 96 ◽  
Author(s):  
K. H. J. Buschow
Keyword(s):  
Physical Properties ◽  
Permanent Magnet ◽  
Permanent Magnets ◽  
Amorphous State ◽  
Tetragonal Structure ◽  
Ternary Compounds ◽  
Alternative Materials

ABSTRACTSeveral ternary compounds of tetragonal structure and with the composition R2Fe14B have found an application as starting materials for permanent magnets. Several physical properties of R2Fe14B compounds will be discussed in relation to the modification in properties that can be obtained by substituting other elements for R, Fe or B. Also investigated is the extent to which it will be possible to find alternative materials differing in structure and composition from R2Fe14B. For this purpose the results obtained on 3d-rich ternaries based on well-known structure types will be reviewed. Included in this survey will be novel ternary intermetallics made by crystallization from the amorphous state. These compounds, though stable enough for applications, are actually metastable. They are not found in the corresponding equilibrium diagrams.

scholarly journals New Concept of Amorphous State and Physical Properties

Kobunshi ◽  
1973 ◽  
Vol 22 (5) ◽  
pp. 258-263 ◽  
Author(s):  
Tisato KAJIYAMA
Keyword(s):  
Physical Properties ◽  
Amorphous State

Investigations of short range order in amorphous Fe-B alloys

1988 ◽  
Vol 46 ◽  
pp. 458-459
Author(s):  
J. Zweck ◽  
H. Hoffmann
Keyword(s):  
Physical Properties ◽  
Short Range ◽  
Short Range Order ◽  
Amorphous State ◽  
High Resolution Electron Microscopy ◽  
Near Neighbor ◽  
Distribution Functions ◽  
Range Order ◽  
Resolution Electron ◽  
Pair Distribution Functions

Amorphous metallic alloys exhibit a large variety of physical properties that often differ from their crystalline counterparts of the same composition. Currently, metallic glasses exist which, to name only a few examples, are either very non-abrasive, soft magnetic and magneto optical, hard, flexible, or resistant to corrosion. These properties are of great technical importance and there are many applications that are based on amorphous alloys. Since physical properties are related to the structure of a material, a better knowledge of the ‘structure’ of the amorphous state is of great interest. In this work, we present pair distribution functions determined from electron diffraction results for amorphous Fe-B alloys of different compositions. From the pair distribution functions one can obtain information about near neighbor distances, the range of a short range order (SRO) for different compositions, and of similarities to crystalline counterparts. These findings will also be compared to results obtained with the use of high resolution electron microscopy (HREM).

Specific Time-Temperature Treatment Preparing the Melt for the Amorphous State

2016 ◽  
Vol 864 ◽  
pp. 55-59
Author(s):  
Vladimir Tsepelev ◽  
Ondrej Zivotsky ◽  
Nadezhda Tsepeleva
Keyword(s):  
Physical Properties ◽  
Amorphous State ◽  
Temperature Treatment ◽  
Magnetic Core ◽  
Chemical Model ◽  
Specific Time ◽  
Annealing Temperatures ◽  
Amorphous Ribbons ◽  
Uniform Composition

Taking into account the concept of the quasi-chemical model of the liquid micro-non-uniform composition and the research made on the physical properties of the Fe-and Co-based melts being crystallized, the unique technology of the melt time-temperature treatment has been developed. Amorphous ribbons produced using this technology require optimal annealing temperatures to be specifically selected. The results of studying nanocrystalline magnetic core’ properties and their structure in the course of annealing at temperatures below and above the optimal ones are presented.

The Photometric Properties of the Ap Stars

1976 ◽  
Vol 32 ◽  
pp. 365-377 ◽  
Author(s):  
B. Hauck
Keyword(s):  
Physical Properties ◽  
Ap Stars

The Ap stars are numerous - the photometric systems tool It would be very tedious to review in detail all that which is in the literature concerning the photometry of the Ap stars. In my opinion it is necessary to examine the problem of the photometric properties of the Ap stars by considering first of all the possibility of deriving some physical properties for the Ap stars, or of detecting new ones. My talk today is prepared in this spirit. The classification by means of photoelectric photometric systems is at the present time very well established for many systems, such as UBV, uvbyβ, Vilnius, Geneva and DDO systems. Details and methods of classification can be found in Golay (1974) or in the proceedings of the Albany Colloquium edited by Philip and Hayes (1975).

The Infection of Cells by Bullet-Shaped Viruses

1969 ◽  
Vol 27 ◽  
pp. 372-373
Author(s):  
Frederick A. Murphy ◽  
Alyne K. Harrison ◽  
Sylvia G. Whitfield
Keyword(s):  
Electron Microscopy ◽  
Physical Properties ◽  
Host Cell ◽  
Thin Section ◽  
Cultured Cells ◽  
Cell Infection ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Section Electron Microscopy

The bullet-shaped viruses are currently classified together on the basis of similarities in virion morphology and physical properties. Biologically and ecologically the member viruses are extremely diverse. In searching for further bases for making comparisons of these agents, the nature of host cell infection, both in vivo and in cultured cells, has been explored by thin-section electron microscopy.

Transmission electron microscopy of composite materials

1988 ◽  
Vol 46 ◽  
pp. 1012-1015
Author(s):  
K.P.D. Lagerlof
Keyword(s):  
Composite Materials ◽  
Physical Properties ◽  
Structural Defects ◽  
Structural Composites ◽  
Multiphase Materials ◽  
Structural Reinforcement ◽  
Transmission Electron ◽  
Reinforced Fiber ◽  
Particulate Reinforced Composites ◽  
Definition Of

Although most materials contain more than one phase, and thus are multiphase materials, the definition of composite materials is commonly used to describe those materials containing more than one phase deliberately added to obtain certain desired physical properties. Composite materials are often classified according to their application, i.e. structural composites and electronic composites, but may also be classified according to the type of compounds making up the composite, i.e. metal/ceramic, ceramic/ceramie and metal/semiconductor composites. For structural composites it is also common to refer to the type of structural reinforcement; whisker-reinforced, fiber-reinforced, or particulate reinforced composites [1-4].For all types of composite materials, it is of fundamental importance to understand the relationship between the microstructure and the observed physical properties, and it is therefore vital to properly characterize the microstructure. The interfaces separating the different phases comprising the composite are of particular interest to understand. In structural composites the interface is often the weakest part, where fracture will nucleate, and in electronic composites structural defects at or near the interface will affect the critical electronic properties.

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