scholarly journals Composite Polyvinylpyrrolidone–Sodium Alginate—Hydroxyapatite Hydrogel Films for Bone Repair and Wound Dressings Applications

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3989
Author(s):  
Inna V. Fadeeva ◽  
Elena S. Trofimchuk ◽  
Anna A. Forysenkova ◽  
Abdulrahman I. Ahmed ◽  
Oleg I. Gnezdilov ◽  
...  
Keyword(s):  
Sodium Alginate ◽  
Bone Repair ◽  
Composite Films ◽  
The Body ◽  
Wound Dressings ◽  
Ex Situ ◽  
Polymer Mixture ◽  
Swelling Properties ◽  
Hydrogel Films

Today, the synthesis of biocompatible and bioresorbable composite materials such as “polymer matrix-mineral constituent,” which stimulate the natural growth of living tissues and the restoration of damaged parts of the body, is one of the challenging problems in regenerative medicine. In this study, composite films of bioresorbable polymers of polyvinylpyrrolidone (PVP) and sodium alginate (SA) with hydroxyapatite (HA) were obtained. HA was introduced by two different methods. In one of them, it was synthesized in situ in a solution of polymer mixture, and in another one, it was added ex situ. Phase composition, microstructure, swelling properties and biocompatibility of films were investigated. The crosslinked composite PVP-SA-HA films exhibit hydrogel swelling characteristics, increasing three times in mass after immersion in a saline solution. It was found that composite PVP-SA-HA hydrogel films containing HA synthesized in situ exhibited acute cytotoxicity, associated with the presence of HA synthesis reaction byproducts—ammonia and ammonium nitrate. On the other hand, the films with HA added ex situ promoted the viability of dental pulp stem cells compared to the films containing only a polymer PVP-SA blend. The developed composite hydrogel films are recommended for such applications, such as membranes in osteoplastic surgery and wound dressing.

In-Situ Characterization of Carbon Nanotube-Polystyrene Composite Deformation

2000 ◽  
Vol 6 (S2) ◽  
pp. 40-41
Author(s):  
D. Qian ◽  
E. C. Dickey ◽  
R. Andrews ◽  
T. Rantell ◽  
B. Safadi
Keyword(s):  
Carbon Nanotubes ◽  
Load Transfer ◽  
Electronic Materials ◽  
Composite Films ◽  
Chemical Vapor ◽  
Ex Situ ◽  
In Situ Tem ◽  
Multiwalled Carbon ◽  
Young’S Moduli

Carbon nanotubes (NTs) have novel electronic properties and exceptionally high Young's moduli on the order of TPa. so NTs have potential applications in advanced composite materials such as conductive polymers, electromagnetic-radio frequency interference (EMI/RFI) shielding material and opto-electronic materials. The utility of the nanotubes in composite applications depends strongly on the ability to disperse the NTs homogeneously throughout the matrix without destroying the integrity of the NTs. Furthermore, interfacial bonding between the NT and matrix is necessary to achieve load transfer across the interface, which is desirable for improving the mechanical properties of polymer composites.In this work, aligned multiwalled carbon nanotubes (MWNTs) produced by continuous chemical vapor deposition (CVD) (see Fig.l), were homogeneously dispersed in polystyrene (PS) matrices by a simple solution-evaporation method. Using this procedure, we made uniform MWNT-PS composite films ∼0.4mm thick for ex-situ mechanical tensile test and very thin films, ∼100nm, for in-situ TEM tests, as shown in Fig.2.

FORMULATION OPTIMIZATION AND EVALUATION OF TINIDAZOLE IN-SITU

2021 ◽  
Vol 10 (2) ◽  
pp. 20-26
Author(s):  
Yaduwanshi Payal ◽  
Goswami Anindya ◽  
Malviya Neelesh
Keyword(s):  
Factorial Design ◽  
Sodium Alginate ◽  
Dosage Form ◽  
Sodium Citrate ◽  
The Body ◽  
Gelling Agent ◽  
Formulation Optimization ◽  
Full Factorial ◽  
32 Full Factorial Design

The study deals with formulation optimization and evaluation of tinidazole gel by using sodium alginate as gelling agent calcium chloride, sodium citrate were used as cross linking agent. The polymeric solution of drug is in solution form before it administered to the body. But after administration when it comes in contact with acidic pH it’s converted into gel form and the drug tinidazole released from the dosage form constantly and slowly. The formulation is effective for the treatment of gastric ulcer because of Helicobacter pylori. 32 full factorial design were used for the optimization of the formulation 12 trial batches were prepared and 9 factorial design batches in which 2 factor 3 level factorial design were used for the optimization. The concentration of sodium alginate, were taken in 3 level low, medium, high and the prepared formulation were evaluated.

Size-dependent Phase Transformations During Point Loading of Silicon

2000 ◽  
Vol 15 (8) ◽  
pp. 1754-1758 ◽  
Author(s):  
A. B. Mann ◽  
D. van Heerden ◽  
J. B. Pethica ◽  
T. P. Weihs
Keyword(s):  
Phase Transformations ◽  
Strong Dependence ◽  
The Body ◽  
Ex Situ ◽  
Stress Fields ◽  
Rhombohedral Structure ◽  
Size Dependent ◽  
Transmission Electron ◽  
Contact Size

Using a unique combination of in situ electrical and acoustical measurements and ex situ transmission electron microscopy, the phase transformations of silicon during point loading were shown to exhibit a strong dependence on the size of the deformed volume. For nanometer-size volumes of silicon, the final phase was the body centered cubic structure BC8, but for larger volumes it was amorphous. The size dependence was explained by considering how shear stress fields vary with contact size and how interfacial effects between the silicon substrate and the BC8 phase determine its stability. For both small and large contacts the presence of a nonmetallic phase (assumed to be the Rhombohedral structure R8) was observed.

scholarly journals Cross-metathesis of polynorbornene with polyoctenamer: a kinetic study

2015 ◽  
Vol 11 ◽  
pp. 1796-1808 ◽  
Author(s):  
Yulia I Denisova ◽  
Maria L Gringolts ◽  
Alexander S Peregudov ◽  
Liya B Krentsel ◽  
Ekaterina A Litmanovich ◽  
...  
Keyword(s):  
Random Copolymer ◽  
Polymer Chains ◽  
Ex Situ ◽  
Polymer Mixture ◽  
Second Stage ◽  
Cross Metathesis ◽  
Whole Process ◽  
Low Concentrations ◽  
Kinetics Of

The cross-metathesis of polynorbornene and polyoctenamer in d-chloroform mediated by the 1st generation Grubbs’ catalyst Cl2(PCy3)2Ru=CHPh is studied by monitoring the kinetics of carbene transformation and evolution of the dyad composition of polymer chains with in situ 1H and ex situ 13C NMR spectroscopy. The results are interpreted in terms of a simple kinetic two-stage model. At the first stage of the reaction all Ru-benzylidene carbenes are transformed into Ru-polyoctenamers within an hour, while the polymer molar mass is considerably decreased. The second stage actually including interpolymeric reactions proceeds much slower and takes one day or more to achieve a random copolymer of norbornene and cyclooctene. Its rate is limited by the interaction of polyoctenamer-bound carbenes with polynorbornene units, which is hampered, presumably due to steric reasons. Polynorbornene-bound carbenes are detected in very low concentrations throughout the whole process thus indicating their higher reactivity, as compared with the polyoctenamer-bound ones. Macroscopic homogeneity of the reacting media is proved by dynamic light scattering from solutions containing the polymer mixture and its components. In general, the studied process can be considered as a new way to unsaturated multiblock statistical copolymers. Their structure can be controlled by the amount of catalyst, mixture composition, and reaction time. It is remarkable that this goal can be achieved with a catalyst that is not suitable for ring-opening metathesis copolymerization of norbornene and cis-cyclooctene because of their substantially different monomer reactivities.

scholarly journals Injuries reflecting intra- and interspecific interactions in the Snake-eyed Skink Ablepharus kitaibelii (Bibron & Bory de Saint-Vincent, 1833) (Squamata, Scincidae) from Bulgaria

Herpetozoa ◽  
2019 ◽  
Vol 32 ◽  
pp. 171-175
Author(s):  
Vladislav Vergilov ◽  
Yurii V. Kornilev
Keyword(s):  
Interspecific Interactions ◽  
The Body ◽  
Ex Situ ◽  
Back Side ◽  
Costs And Benefits ◽  
Predator Pressure ◽  
Behavioral Studies ◽  
The Individual ◽  
First Time

The Snake-eyed Skink’s intra- and inter-specific interactions and their impacts on the individual (e.g. injuries) have received little attention so far. As part of copulation, male lizards bite the females; observations confirm an old report that bites occur in the fore side of the body, along with more recently published information about the back side. Additionally, out of 435 individuals observed in situ, 10 had missing extremities (toes, ankles, etc.); however, further studies should identify the causes of such injury, e.g. male-male combat, predators. For the first time, an adult male was observed biting a juvenile ex situ; the specific reasons, however, remain unknown. This report should generate further interest in ecological and behavioral studies, assessing the costs and benefits to potential territorial defense, intra-specific combat, and predator pressure and escape mechanisms.

Preparation and properties of ZnO/sodium alginate bi-layered hydrogel films as novel wound dressings

2019 ◽  
Vol 43 (22) ◽  
pp. 8684-8693 ◽  
Author(s):  
Tingting Wang ◽  
Jinqing Wang ◽  
Rui Wang ◽  
Peilin Yuan ◽  
Zengjie Fan ◽  
...  
Keyword(s):  
Sodium Alginate ◽  
Wound Dressings ◽  
Natural Material ◽  
Biomedical Field ◽  
Hydrogel Films

As one kind of natural material, alginate has been widely investigated and used in the biomedical field.

scholarly journals Bacterial Cellulose as a Versatile Platform for Research and Development of Biomedical Materials

Processes ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 624 ◽  
Author(s):  
Selestina Gorgieva
Keyword(s):  
Bacterial Cellulose ◽  
High Purity ◽  
Antimicrobial Properties ◽  
Wound Dressings ◽  
Ex Situ ◽  
Native Form ◽  
Multifunctional Compounds ◽  
Ultra High Purity ◽  
Cell Affinity

The unique pool of features found in intracellular and extracellular bacterial biopolymers attracts a lot of research, with bacterial cellulose (BC) being one of the most versatile and common. BC is an exopolysaccharide consisting solely of cellulose, and the variation in the production process can vary its shape or even its composition when compounding is applied in situ. Together with ex situ modification pathways, including specialised polymers, particles or exclusively functional groups, BC provides a robust platform that yields complex multifunctional compounds that go far beyond ultra-high purity, intrinsic hydrophilicity, mechanical strength and biocompatibility to introduce bioactive, (pH, thermal, electro) responsive, conductive and ‘smart’ properties. This review summarises the research outcomes in BC-medical applications, focusing mainly on data from the past decade (i.e., 2010–2020), with special emphasis on BC nanocomposites as materials and devices applicable in medicine. The high purity and unique structural/mechanical features, in addition to its capacity to closely adhere to irregular skin surfaces, skin tolerance, and demonstrated efficacy in wound healing, all stand as valuable attributes advantageous in topical drug delivery. Numerous studies prove BC compatibility with various human cells, with modifications even improving cell affinity and viability. Even BC represents a physical barrier that can reduce the penetration of bacteria into the tissue, but in its native form does not exhibit antimicrobial properties, therefore carious modifications have been made or specific compounds added to confer antimicrobial or anti-inflammatory properties. Progress in the use of BC-compounds as wound dressings, vascular grafts, and scaffolds for the treatment of cartilage, bone and osteochondral defects, the role as a basement membrane in blood-brain barrier models and many more are discussed to particular extent, emphasising the need for BC compounding to meet specific requirements.

An in situ and ex situ TEM study of the formation of thin cobalt silicide films by molecular beam epitaxy on the silicon (100) surface

1988 ◽  
Vol 46 ◽  
pp. 884-885
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove ◽  
R. T. Tung
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Defect Density ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Metal Base ◽  
In Situ Experiments ◽  
Potential Applications

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.

The use of transmission and analytical electron microscopy in studying reactions and phase transformations in thin film

1993 ◽  
Vol 51 ◽  
pp. 842-843
Author(s):  
K. Barmak
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Transformations ◽  
Analytical Electron Microscopy ◽  
Ex Situ ◽  
Multilayer Thin Films ◽  
Absolute Concentration ◽  
Analytical Electron ◽  
Deposition Step

Generally, processing of thin films involves several annealing steps in addition to the deposition step. During the annealing steps, diffusion, transformations and reactions take place. In this paper, examples of the use of TEM and AEM for ex situ and in situ studies of reactions and phase transformations in thin films will be presented.The ex situ studies were carried out on Nb/Al multilayer thin films annealed to different stages of reaction. Figure 1 shows a multilayer with dNb = 383 and dAl = 117 nm annealed at 750°C for 4 hours. As can be seen in the micrograph, there are four phases, Nb/Nb3-xAl/Nb2-xAl/NbAl3, present in the film at this stage of the reaction. The composition of each of the four regions marked 1-4 was obtained by EDX analysis. The absolute concentration in each region could not be determined due to the lack of thickness and geometry parameters that were required to make the necessary absorption and fluorescence corrections.

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