scholarly journals Surface mobility of molecular glasses and its importance in physical stability

2016 ◽  
Vol 100 ◽  
pp. 3-9 ◽  
Author(s):  
Lian Yu
Keyword(s):  
Physical Stability ◽  
Molecular Glasses ◽  
Surface Mobility

scholarly journals Surface mobility in amorphous selenium and comparison with organic molecular glasses

2021 ◽  
Vol 154 (7) ◽  
pp. 074703
Author(s):  
Jaroslav Barták ◽  
Jirí Málek ◽  
Kushal Bagchi ◽  
M. D. Ediger ◽  
Yuhui Li ◽  
...  
Keyword(s):  
Amorphous Selenium ◽  
Molecular Glasses ◽  
Surface Mobility

Diffraction from arrays of antiphase boundaries in ordered III-V alloys

1987 ◽  
Vol 45 ◽  
pp. 312-313
Author(s):  
T. S. Kuan
Keyword(s):  
High Surface ◽  
Growth Conditions ◽  
Ternary Alloys ◽  
Local Growth ◽  
Antiphase Boundaries ◽  
Surface Mobility ◽  
Ordered Phases ◽  
Diffraction Patterns ◽  
Atomically Flat ◽  
Degree Of Order

Recent electron diffraction studies have found ordered phases in AlxGa1-xAs, GaAsxSb1-x, and InxGa1-xAs alloy systems, and these ordered phases are likely to be found in many other III-V ternary alloys as well. The presence of ordered phases in these alloys was detected in the diffraction patterns through the appearance of superstructure reflections between the Bragg peaks (Fig. 1). The ordered phase observed in the AlxGa1-xAs and InxGa1-xAs systems is of the CuAu-I type, whereas in GaAsxSb1-x this phase and a chalcopyrite type ordered phase can be present simultaneously. The degree of order in these alloys is strongly dependent on the growth conditions, and during the growth of these alloys, high surface mobility of the depositing species is essential for the onset of ordering. Thus, the growth on atomically flat (110) surfaces usually produces much stronger ordering than the growth on (100) surfaces. The degree of order is also affected by the presence of antiphase boundaries (APBs) in the ordered phase. As shown in Fig. 2(a), a perfectly ordered In0.5Ga0.5As structure grown along the <110> direction consists of alternating InAs and GaAs monolayers, but due to local growth fluctuations, two types of APBs can occur: one involves two consecutive InAs monolayers and the other involves two consecutive GaAs monolayers.

Ultra high resolution SEM at high voltage images individual fab fragments applied as molecular label to cell surface receptors

1989 ◽  
Vol 47 ◽  
pp. 70-71
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
High Resolution ◽  
High Energy ◽  
Metal Coating ◽  
Beam Diameter ◽  
Surface Receptors ◽  
Surface Mobility ◽  
Metal Atoms ◽  
Shadowing Effect ◽  
Imaging Mode ◽  
Deposition Techniques

Topographic ultra high resolution can now routinely be established on bulk samples in cold field emission scanning electron microscopy with a second generation of microscopes (FSEM) designed to provide 0.5 nm probe diameters. If such small probes are used for high magnification imaging, topographic contrast is so high that remarkably fine details can be imaged on 2DMSO/osmium-impregnated specimens at ribosome surfaces even without a metal coating. On TCH/osmium-impregnated specimens topographic resolution can be increased further if the SE-I imaging mode is applied. This requires that beam diameter and metal coating thickness be made smaller than the SE range of ~1 nm and background signal contributions be reduced. Subnanometer small probes can be obtained (only) at high accelerating voltages. Subnanometer thin continuous metal films can be produced under the following conditions: self-shadowing effect between metal atoms must be reduced through appropriate deposition techniques and surface mobility of metal atoms must be diminished through high energy sputtering and/or specimen cooling.

High Autonomy Lunar Surface Mobility Systems

2006 ◽  
Author(s):  
Ernesto Vallerani ◽  
Alberto Della Torre ◽  
Gian Paolo Guizzo ◽  
Igor Vukman
Keyword(s):  
Lunar Surface ◽  
Surface Mobility

Photostability Study on Character and Antioxidant Activity of Tomato Extract (Solanum lycopersicum l.) in Nanostructured Lipid Carrier (NLC) and Conventional Creame

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Noorma Rosita ◽  
Dewi Haryadi ◽  
Tristiana Erawati ◽  
Rossa Nanda ◽  
Widji Soeratri
Keyword(s):  
Antioxidant Activity ◽  
Physical Stability ◽  
Nanostructured Lipid Carrier ◽  
Uvb Radiation ◽  
K Value ◽  
Antioxidant Power ◽  
Solanum Lycopersicum L ◽  
Tomato Extract ◽  
Dpph Method ◽  
High Shear Homogenization

The aim of this study was to investigate the ability of NLC in increasing photostability of tomato extract in term of antioxidant activity. Photostability testing on antioxidant activity of samples were conducted by accelerating method using UVB radiation 32.400 joule for 21 hours radiation. Antioxidant activity was measured by DPPH method. NLC was made by High Shear Homogenization (HPH) method at 24000 rpm for 4 cycles, while conventional creame was made by low speed at 400 rpm. The product were characterized include: pH, viscosity, and particle size. There were had difference characters and physical stability. NLC had smaller size, more homogenous and more stable than conventional creame. It was known that stability of antioxidant activity of tomato extract in NLC system higher than in conventional creame. That was showed with k value, as constanta of rate scavenging activity decreasing in antioxidant power between time (Sigma 2-tail less than 0.005) of NLC and conventional creame were: 2.03x10-2 %/hour ±0.08 (3.94) and 4.71x 10-2 %/ hour ±0.23 (4.88) respectively.

Applications of Ion Exchange Resin in Oral Drug Delivery Systems

2017 ◽  
Vol 7 (03) ◽  
Author(s):  
Kathpalia Harsha ◽  
Das Sukanya
Keyword(s):  
Drug Delivery ◽  
Ion Exchange ◽  
Drug Delivery Systems ◽  
Oral Drug Delivery ◽  
Physical Stability ◽  
Delivery Systems ◽  
Oral Drug ◽  
Ion Exchange Resins ◽  
Exchange Resins ◽  
Oral Drug Delivery Systems

Ion Exchange Resins (IER) are insoluble polymers having styrene divinylbenzene copolymer backbone that contain acidic or basic functional groups and have the ability to exchange counter ions with the surrounding aqueous solutions. From the past many years they have been widely used for purification and softening of water and in chromatographic columns, however recently their use in pharmaceutical industry has gained considerable importance. Due to the physical stability and inert nature of the resins, they can be used as a versatile vehicle to design several modified release dosage forms The ionizable drug is complexed with the resin owing to the property of ion exchange. This resin complex dissociatesin vivo to release the drug. Based on the dissociation strength of the drug from the drug resin complex, various release patterns can be achieved. Many formulation glitches can be circumvented using ion exchange resins such as bitter taste and deliquescence. These resins also aid in enhancing disintegrationand stability of formulation. This review focuses on different types of ion exchange resins, their preparation methods, chemistry, properties, incompatibilities and their application in various oral drug delivery systems as well as highlighting their use as therapeutic agents.

A Review on Microsponge Drug Delivery System

2020 ◽  
Vol 10 (2) ◽  
pp. 53-59
Author(s):  
Bharathi M ◽  
Mullaikodi O ◽  
Rajalingam D ◽  
Gnanasekar N ◽  
Kesavan M
Keyword(s):  
Drug Delivery ◽  
Drug Delivery System ◽  
Delivery System ◽  
Physical Stability ◽  
Current Investigation ◽  
Considerable Time ◽  
Polymeric Structure ◽  
Point Of Interest ◽  
Time Period ◽  
Time Specific

A Microsponge (MS) is an extremely interconnected, permeable, polymeric structure that involves permeable microparticles trapping and discharging through the skin for a considerable time period. Drug delivery system (DDS) offer extended discharge with less degradation, improved physical stability along with better tolerance. The main intend of any DDS is to achieve the required amount of drug in plasma to produce the desired therapeutic and non-poisonous effect over a prolonged period of time. Specific methods for preparing MS were reviewed in this current investigation, and their pharmaceutical implementations were signed. MS have major DDS point of interest. It also improves stability, increased flexibility in formulation and increased elegance. In fact, numerous studies have reported that MS supplies are not allergic, mutagenic, and poisonous. MS creativity is used in products such as sunscreen, prescription, cosmetics, and OTC skin care. This inquiry primarily focuses on the different methods used to identify, plan and exploit MS.

Influence of β-Cyclodextrin and Hydroxypropyl-β-Cyclodextrin on Enhancement of Solubility and Dissolution of Isradipine

2017 ◽  
Vol 10 (3) ◽  
pp. 3752-3757
Author(s):  
Narendar D ◽  
Ettireddy S
Keyword(s):  
Inclusion Complex ◽  
Dissolution Rate ◽  
Solid Dispersions ◽  
Physical Stability ◽  
Molecular Complexes ◽  
In Vitro Dissolution ◽  
Molar Ratio ◽  
Phase Solubility ◽  
Cyclodextrin Complexation

The content of this investigation was to study the influence of β-cyclodextrin and hydroxy propyl-β-cyclodextrin complexation on enhancement of solubility and dissolution rate of isradipine. Based on preliminary phase solubility studies, solid complexes prepared by freeze drying method in 1:1 molar ratio were selected and characterized by DSC for confirmation of complex formation. Prepared solid dispersions were evaluated for drug content, solubility and in vitro dissolution. The physical stability of optimized formulation was studied at refrigerated and room temperature for 2 months. Solid state characterization of optimized complex performed by DSC and XRD studies.  Dissolution rate of isradipine was increased compared with pure drug and more with HP-β-CD inclusion complex than β-CD. DSC and XRD analyzes that drug was in amorphous form, when the drug was incorporated as isradipine β-CD and HP-β-CD inclusion complex. Stability studies resulted in low or no variations in the percentage of complexation efficiency suggesting good stability of molecular complexes. The results conclusively demonstrated that the enhancement of solubility and dissolution rate of isradipine by drug-cyclodextrin complexation was achieved.   

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