scholarly journals Controlled production of alginate nanocomposites with incorporated silver nanoparticles aimed for biomedical applications

2012 ◽  
Vol 77 (12) ◽  
pp. 1709-1722 ◽  
Author(s):  
Jasmina Stojkovska ◽  
Jovana Zvicer ◽  
Zeljka Jovanovic ◽  
Vesna Miskovic-Stankovic ◽  
Bojana Obradovic
Keyword(s):  
Silver Nanoparticles ◽  
Electrostatic Potential ◽  
Biomedical Applications ◽  
Dynamic Compression ◽  
Compression Modulus ◽  
Biomechanical Properties ◽  
The Other ◽  
Unconfined Compression ◽  
Alginate Hydrogel ◽  
Other Hand

Production of nanocomposite alginate microbeads with electrochemically synthesized silver nanoparticles (AgNPs) based on electrostatic extrusion technique was investigated with respect to potentials for utilization in pharmaceutical and biomedical applications. It was shown that electrochemical synthesis of AgNPs results in reduction of practically all Ag+ ions present in the initial solution yielding stable Ag/alginate colloid solutions that were demonstrated to be suitable for sterilization, manipulation, and electrostatic extrusion with retention of AgNPs. Presence of AgNPs in alginate colloid solutions had negligible effects on the size of the produced Ag/alginate microbeads, which was chiefly determined by the applied electrostatic potential during the extrusion. On the other hand, incorporation of AgNPs within the alginate hydrogel induced slight changes in biomechanical properties determined in a biomimetic bioreactor, so that packed beds of nanocomposite Ag/alginate microbeads exhibited slightly higher dynamic compression modulus as compared to that of control alginate microbeads (154 ? 4 and 141 ? 2 kPa, respectively). On the other hand, equilibrium unconfined compression modulus was significantly lower for nanocomposite microbeads as compared to that of controls (34 ? 2 and 47 ? 0.5 kPa, respectively).

scholarly journals Recent Applications of Nanomaterials in Prosthodontics

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Wei Wang ◽  
Susan Liao ◽  
Yuhe Zhu ◽  
Ming Liu ◽  
Qian Zhao ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Surface Hardness ◽  
Filler Loading ◽  
The Other ◽  
Research Progress ◽  
Polymerization Shrinkage ◽  
Other Hand ◽  
Micron Size

In recent years, lots of researches have been launched on nanomaterials for biomedical applications. It has been shown that the performances of many biomaterials used in prosthodontics have been significantly enhanced after their scales were reduced by nanotechnology, from micron-size into nanosize. On the other hand, many nanocomposites composed of nanomaterials and traditional metals, ceramics, resin, or other matrix materials have been widely used in prosthodontics because their properties, such as modulus elasticity, surface hardness, polymerization shrinkage, and filler loading, were significantly increased after the addition of the nanomaterials. In this paper, the latest research progress on the applications of nanometals, nanoceramic materials, nanoresin materials, and other nanomaterials in prosthodontics was reviewed, which not only gives a detailed description of the new related investigations, but also hopefully provides important elicitation for future researches in this field.

Monte Carlo simulation of proton therapy using bio-nanomaterials

2016 ◽  
Vol 15 (3) ◽  
pp. 290-295
Author(s):  
Chafika Belamri ◽  
Anis Samy Amine Dib ◽  
Ahmed H. Belbachir
Keyword(s):  
Monte Carlo Simulation ◽  
Gold Nanoparticles ◽  
Silver Nanoparticles ◽  
Monte Carlo ◽  
Cancer Therapy ◽  
Proton Therapy ◽  
Platinum Nanoparticles ◽  
The Other ◽  
Other Hand

AbstractIntroductionIn recent years, there has been a spectacular development in nanomedicine field with new nanoparticles for diagnosis and cancer therapy. Although most researchers have been always interested in gold nanoparticles (GNPs)Materials and methodsIn the present work we present a comparison between the use of bio-nanomaterials in proton therapy.ConclusionConsequently, our results show that platinum nanoparticles (PtNPs) present an interesting advantages comparing with GNPs and silver nanoparticles. On the other hand, the use of PtNPs facilitates in a considerable way the proton therapy.

Glycosaminoglycan and Collagen Remodeling During In Vitro Dynamic Compression of Articular Cartilage: Experiments and Finite Element Modeling

2013 ◽  
Author(s):  
Kevin A. Yamauchi ◽  
Christopher B. Raub ◽  
Albert C. Chen ◽  
Robert L. Sah ◽  
Scott J. Hazelwood ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Dynamic Compression ◽  
Fluid Velocity ◽  
Biomechanical Properties ◽  
Mechanical Stimuli ◽  
Unconfined Compression ◽  
Growth Data ◽  
Collagen Remodeling ◽  
Continuum Mixture Model

The biomechanical properties of articular cartilage (AC) can be altered by chemical and mechanical stimuli. Dynamic unconfined compression (UCC) has been shown to increase biosynthesis at moderate strain amplitudes (1–4%) and frequencies from 0.01Hz. to 0.1Hz [1]. Furthermore, interstitial fluid velocity and maximum principle strain have been proposed as candidates for controlling glycosaminoglycan (GAG) and collagen (COL) remodeling, respectively [2,3]. The goal of this study was to integrate in vitro growth data, including biochemical and microstructural properties, into a computational continuum mixture model to elucidate potential mechanical triggers for AC tissue remodeling.

scholarly journals Management of Aedes aegypti using green silver nanoparticles and botanical extracts

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
Hassan Saeed ◽  
Muhammad Muhammad Tariq ◽  
Asim Gulzar ◽  
Zia-ur-Rehman Mashwani ◽  
Muhammad Safian Bajwa
Keyword(s):  
Silver Nanoparticles ◽  
Aedes Aegypti ◽  
Plant Extracts ◽  
Negative Impact ◽  
The Other ◽  
Lc50 Value ◽  
Development Of Resistance ◽  
Other Hand ◽  
Botanical Extracts

The excessive use of insecticides has led to development of resistance in Aedes aegypti and negative impact on environment and non-target organisms. To overcome these problems, emphasis is being laid for alternatives, therefore, in the present study, the toxicity of eight plant extracts and their green synthesized nanoparticles were evaluated against A. aegypti. Clove extracts caused the maximum mortalities of 92% and 90% of 3rd and 4th instar larvae of A. aegypti followed by ginger causing 90% and 78% mortalities respectively. On the other hand, the minimum mortalities of these larvae were caused by neem and garlic extracts. In case of green silver nanoparticles, the maximum mortalities of 3rd and 4th instar larvae of A. aegypti were caused by clove followed by ginger while the minimum mortalities were caused by nanoparticles of datura followed by garlic. All the green silver nanoparticles caused mortalities of both the instars of the mosquito above 80% with few exceptions. Datura extracts showed the minimum LC50 values after 72 hours of application followed by neem against the 3rd and 4th instar larvae of A. aegypti.  The highest LC50 value was observed in case of ginger followed by clove and eucalyptus. In case of silver nanoparticles, the minimum LC50 values after 72 hours were recorded in case of datura, neem and garlic while the values were the maximum in case of clove and ginger. The LC50 values decreased with the passage of time.

scholarly journals Conformational and Topology Analysis of Diphenylthiourea and Diarylhalidethiourea Compounds Using DFT

2020 ◽  
Vol 20 (2) ◽  
pp. 264
Author(s):  
Nur Najwa-Alyani Mohd Nabil ◽  
Lee Sin Ang
Keyword(s):  
Electrostatic Potential ◽  
The Other ◽  
Potential Surfaces ◽  
Topology Analysis ◽  
Covalent Interaction ◽  
And Topology ◽  
Other Hand ◽  
Phenyl Rings ◽  
Energetic Analysis ◽  
Structural Arrangements

The disubstituted thiourea compounds have shown its reliability on their usages in various industries compared to the thiourea compounds. However, they also show capability to exist in different configurations, which would render them to possess different properties and hence affect their usability by unsuspected users. In this study, investigation was carried out on the polymorphism of five disubstituted thiourea compounds in which the phenyl rings and arylhalide acted as substituents. Using the B3LYP/DEF2–TZVP model chemistry with D3–BJ and gCP correctional schemes, the energetic analysis on the possible structural arrangements of the compounds was performed. The topology analysis of non-covalent interaction and electrostatic potential surfaces was used for understanding the interaction and reactivity of the constitute molecules of the compounds. Energetic results show that for all interested compounds, CT and TT configurations may coexist. Between the two type of substituents, phenyl substituted molecules are more flexible with better capability to be nucleophilic compound. On the other hand, the arylhalide substituted molecules form better electrophilic compounds. The reactive sites of the molecules rotated to the stable new configurations are similar to the molecules in their original configurations observed from experiments.

The Influence of Silver Nanoparticle Sizes on Antibacterial Activity, Cytotoxicity and Genotoxicity of Alginate Hydrogel Beads Containing Silver Nanoparticles

2019 ◽  
Vol 886 ◽  
pp. 70-77
Author(s):  
Pawika Mahasawat ◽  
Soraya Mudtaleb ◽  
Pratumporn Eaidprap
Keyword(s):  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Biological Activity ◽  
Biomedical Applications ◽  
Hacat Cells ◽  
Alginate Hydrogel ◽  
Hydrogel Beads ◽  
E Coli ◽  
Low Cytotoxicity ◽  
Nanoparticle Sizes

Sizes of silver nanoparticles (AgNPs) have been shown to affect the biological activity of AgNPs. Hydrogel beads loaded with AgNPs have been extensively employed for biomedical applications. However, the influence of AgNPs sizes on biological activity of AgNP-loaded hydrogel beads has not much studied. Our objectives were to investigate the effect of AgNP sizes on the antibacterial activity, the cyto- and genotoxicity of AgNPs/alginate hydrogel beads. AgNPs of different sizes (⁓10 nm for S-AgNPs, and ⁓50 nm for L-AgNPs) were incorporated into alginate hydrogel beads during the preparation. The results showed that, S-AgNPs/alginate hydrogel beads (⁓89% inhibition) at AgNP concentration of 10 µg/ml tended to inhibit the growth of E. coli greater than L-AgNPs/alginate hydrogel beads (⁓49% inhibition) at the same dose. Moreover, at this effective antibacterial concentration (10 µg/ml), S-AgNPs/alginate hydrogel beads exhibited weak cytotoxic effect to HaCaT cells whereas L-AgNPs/alginate hydrogel beads showed non-cytotoxicity to this cell line. Furthermore, treatment of HaCaT cells with 10 µg/ml of S-AgNPs/ or L-AgNPs/alginate hydrogel beads did not result in a significant change in %DNA in tail when compared to untreated cells. Therefore, these AgNPs/alginate hydrogel beads, especially with smaller sized AgNPs, can be used as an antibacterial biomaterial with low cytotoxicity and genotoxicity to human cells.

Unusual Effect of Oxygen on the Mechanical Behavior of a β-Type Titanium Alloy Developed for Biomedical Applications

2012 ◽  
Vol 706-709 ◽  
pp. 135-142 ◽  
Author(s):  
Mitsuo Niinomi ◽  
Masaaki Nakai
Keyword(s):  
Tensile Strength ◽  
Titanium Alloy ◽  
Mechanical Behavior ◽  
Titanium Alloys ◽  
Biomedical Applications ◽  
The Other ◽  
Excess Oxygen ◽  
Ω Phase ◽  
Other Hand ◽  
Effect Of Oxygen

Oxygen enhances the strength of titanium alloys in general; however, excess oxygen can make titanium alloys brittle. On the other hand, oxygen enhances the precipitation of the α phase and suppresses the formation of the ω phase. Thus, using the optimal amount of oxygen is important to improve the mechanical properties of titanium alloys. The role of oxygen in titanium alloys is still not well understood. The effect of oxygen on the mechanical behavior of a β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (referred to as TNTZ), which is used for biomedical applications, was investigated in this study. Oxygen was found to stabilize the ω phase in TNTZ. This behavior of oxygen is unusual considering the known behavior of oxygen in titanium alloys: oxygen is known to suppress the formation of the ω phase in titanium alloys. A small amount of oxygen increases the tensile strength but decreases the ductility of TNTZ. On the other hand, a large amount of oxygen, of around 0.7 mass%, increases both the tensile strength and the ductility of TNTZ. This phenomenon is unexpected.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

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