scholarly journals An in-vitro evaluation of mechanical and esthetic properties of orthodontic sealants

2014 ◽  
Vol 08 (04) ◽  
pp. 487-492 ◽  
Author(s):  
Thyagaseely Sheela Premaraj ◽  
Nima Rohani ◽  
David Covey ◽  
Sundaralingam Premaraj ◽  
Yi Hua ◽  
...  
Keyword(s):  
Particle Size ◽  
Wear Resistance ◽  
Surface Morphology ◽  
Wear Test ◽  
Color Stability ◽  
Micro Hardness ◽  
Wear Properties ◽  
Significant Difference ◽  
Sem Imaging

ABSTRACT Objective: To evaluate mechanical and esthetic Properties of two commercially available orthodontic sealants: Opal®Seal (OS) and L.E.D. Pro Seal (PS). Materials and Methods: Discs of each sealant were prepared to test the following properties: Micro hardness, wear resistance and color stability. Samples were randomly selected after the wear test for SEM imaging to analyze surface morphology. Results: OS was significantly harder than PS (P < 0.001). PS was significantly more wear resistant than OS (P < 0.05). PS showed a greater ΔE*ab (increased staining) when placed in wine or coffee showing a significant difference (P < 0.05). SEM showed particle size, shape and distribution were different for PS and OS reflecting the pattern seen on wear surfaces. Conclusion: Both orthodontic sealants are beneficial for protecting enamel. However with better wear properties PS was superior in resisting mechanical stresses. OS was more color stable.

scholarly journals Preliminary In Vitro Wear Assessment of Ceramic Cemented Femoral Components Coupled with Polyethylene Menisci

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2112
Author(s):  
Saverio Affatato ◽  
Paolo Erani ◽  
Maurizio Fersini ◽  
Vincenzo Contaldi ◽  
Anna Rita Terrizzi ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Wear Resistance ◽  
Monoclinic Phase ◽  
Calf Serum ◽  
Wear Test ◽  
Clinical Test ◽  
Preliminary Evaluation ◽  
Before And After ◽  
Roughness Measurements

Success of total knee replacement (TKR) depends on the prosthetic design and materials. The use of metal components is well established with the disadvantage of allergic reactions. Ceramics have been recently proposed because of high wear resistance, excellent biocompatibility, wettability, and suitable mechanical properties. This study was aimed at investigating in vitro wear resistance of Zirconia Toughened Alumina (ZTA)/Ultra-high-molecular-weight polyethylene (UHMWPE) of TKR femoral components. An in vitro protocol was designed with the application of relevant load profile, 6-degrees-of-freedom knee simulator, and 8 × 105 cycles on the ZTA/UHMWPE configuration under bovine calf serum. Before and after wear test, the femoral components were investigated by using the Scanning Electron Microscope (SEM) and the X-Ray Diffraction (XRD) analyses, and stylus surface roughness measurements. The proposed pre-clinical test yielded repeatable results. In particular, gravimetric results showed that, after 8 × 105 cycles, the mean weight loss of the polyethylene mobile components is 5.3 ± 1.1 mg. The surface roughness measurements (Ramax) performed after the wear test showed no significant variation on the UHMWPE menisci. A slight increase of roughness has been found on the ZTA (0.02 µm before wear test, 0.28 µm after the test). SEM observations did not show significant modification of the surface morphology. Tetragonal to monoclinic phase ratio was measured by XRD before and after wear test to evaluate stability of tetragonal ZrO2 phase. Minimal conversion of tetragonal to monoclinic phase was found from 5.4 to 8%. Although this study is a preliminary evaluation limited to in vitro tests, it provides novel pre-clinical indications about the potential of ceramic TKR femoral components.

An Experimental Investigation on Mechanical and Wear Properties of Al7075/SiCp Composites: Effect of SiC Content and Particle Size

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Thella Babu Rao
Keyword(s):  
Particle Size ◽  
Tensile Strength ◽  
Wear Resistance ◽  
Ultimate Tensile Strength ◽  
Matrix Material ◽  
Mechanical Tests ◽  
Experimental Investigations ◽  
Wear Properties ◽  
Sic Particles ◽  
Sic Particle

One of the major advantages of metal matrix composites (MMCs) is that their tailorable properties meet the specific requirements of a particular application. This paper deals with the experimental investigations done on the effects of the reinforcement particulate size and content on the Al7075/SiC composite. The composites were manufactured using stir casting technique. The effect of SiC particle size (25, 50, and 75 μm) and particulate content (5, 10, and 15 wt %) on the microstructural, mechanical properties, and wear rate of the composites was studied and the results were analyzed for varied conditions of reinforcement. Scanning electron microscope (SEM) examinations were used to assess the dispersion of SiC particles reinforced into the matrix alloy and was found with reasonably uniform with minimal particle agglomerations and with good interfacial bonding between the particles and matrix material. X-ray diffraction (XRD) analysis confirmed the presence of Al and SiC with the composite. The results of mechanical tests showed that the increasing SiC particle size and content considerably enhanced the ultimate tensile strength and hardness of the composites while the ductility at this condition was decreased. The highest ultimate tensile strength of 310 MPa and hardness of 126 BHN were observed for the composites containing 15 wt %. SiC at 75 μm. Lesser the wear resistance of the reference alloy while it was enhanced up to 40% with the composites. The wear resistance was increased up to 1200 m of sliding distance for all the composites, whereas for the composite containing 75 μm SiC particles, it was extended up to 1800 m.

scholarly journals EVALUATION OF STABILITY OF ROPINIROLE HYDROCHLORIDE AND PRAMIPEXOLE DIHYDROCHLORIDE MICROSPHERES AT ACCELERATED CONDITION

2018 ◽  
Vol 10 (4) ◽  
pp. 82
Author(s):  
Koyel Kar ◽  
R. N. Pal ◽  
Gouranga Nandi
Keyword(s):  
Particle Size ◽  
Drug Release ◽  
Surface Morphology ◽  
Shelf Life ◽  
Stability Study ◽  
In Vitro Drug Release ◽  
Drug Content ◽  
Ropinirole Hydrochloride ◽  
Pramipexole Dihydrochloride

Objective: The objective of the present work was to conduct accelerated stability study as per international council for harmonisation (ICH) guidelines and to establish shelf life of controlled release dosage form of ropinirole hydrochloride and pramipexole dihydrochloride microspheres for a period of 6 mo.Methods: Most optimized batch of ropinirole hydrochloride and pramipexole dihydrochloride (F12 and M12 respectively) were selected and subjected to exhaustive stability testing by keeping the sample in stability oven for a period of 3 and 6 mo. Various parameters like surface morphology, particle size, drug content, in vitro drug release and shelf life were evaluated at 3 and 6 mo period. The surface morphology of the formulated microspheres was determined by scanning electron microscopy (SEM). The particle size of the microspheres was estimated by optical microscopy method. The drug content was assayed by the help of ultra-violet spectrophotometer (UV). The in vitro drug release was performed by using Paddle II type dissolution apparatus and the filtrate was analyzed by UV spectrophotometer. The shelf life of the optimized microspheres was calculated by using the rate constant value of the zero-order reaction.Results: A minor change was recorded in average particle size of F12 and M12 microspheres after storage for 6 mo. For F12 and M12, initially the particle size was 130.00 µm and 128.92 µm respectively and after 6 mo it was found to be 130.92 µm and 128.99 µm respectively. There was no change in surface morphology of F12 and M12 microspheres after 6 mo of storage. The shape of microspheres remained spherical and smooth after 6 mo. An insignificant difference of drug content was recorded after 6 mo compared to the freshly prepared formulation. For F12 and M12, 94.50% and 93.77% of the drug was present initially and after 6 mo 94.45% and 93.72% of the drug was recorded. In vitro drug release was recorded after 6 mo for F12 and M12. Initially, 97.99% and 97.69% of the drug was released till 14th hour respectively for F12 and M12. After 6 mo, 98.23% and 97.99% of the drug was released respectively. The percentage residual drug content revealed that the degradation of microspheres was low. Considering the initial percentage residual drug content as 100%, 99.94% of the drug was recorded for both F12 and M12. The shelf life for F12 and M12 was found to be 10 y 52 d and 10 y 70 d respectively which were determined by the zero-order kinetic equation.Conclusion: A more or less similar surface morphology, particle size, drug content and percent of drug release before and after stability study confirmed the stability of F12 and M12 microspheres after storage for 6 mo and prove the efficacy of the microspheres in the site-specific delivery of drugs in Parkinson’s disease.

scholarly journals Preparation and preclinical evaluation of aceclofenac loaded pectinate mucoadhesive microspheres

2012 ◽  
Vol 2 (1) ◽  
pp. 8 ◽  
Author(s):  
Santanu Chakraborty ◽  
Priyanka Nayak ◽  
Bala Murali Krishna ◽  
Madhusmruti Khandai ◽  
Ashoke Kumar Ghosh
Keyword(s):  
Particle Size ◽  
Drug Release ◽  
Polymer Concentration ◽  
Research Work ◽  
In Vivo Studies ◽  
Systemic Absorption ◽  
Cross Linking ◽  
Significant Difference

The aim of the present research work was to fabricate aceclofenac loaded pectinate microspheres by ionic gelation method and evaluate the effect of different cross-linking agents and polymer concentration on particle size, encapsulation efficacy and drug release behavior. It was also investigated that whether this pectinate dosage form was able to target the drug release in intestinal region and prevent the different side effect associated with the drug in stomach or not. It was observed that particle size, encapsulation efficacy and in vitro drug release were largely depended on polymer concentration and cross-linking agents. It was also observed that pectinate microspheres showed excellent pH depended mucoadhesive properties and they were able to restrict the drug release in stomach. <em>In vitro</em> drug release study showed that alminium-pectinate microspheres have more sustaining property as compared to barium-pectinate microspheres. Holm-Sidak multiple comparison analysis suggested a significant difference in measured t<sub>50%</sub> values among all the formulations with same cross-linking agent. In vivo studies revealed that the anti inflammatory and analgesic effects induced by pectinate microspheres were significantly high and prolonged as compared to pure drug. So, pectinate microspheres can be an excellent carrier for targeting the delivery of aceclofenac as well as help in improving the patient compliance by prolonging the systemic absorption.

scholarly journals IN VITRO ANTI-PLATELET AGGREGATION ACTIVITY OF HYDROXYPROPYL CELLULOSE–CYSTEAMINE BASED NANOPARTICLES CONTAINING CRUDE BROMELAIN

2020 ◽  
pp. 95-98
Author(s):  
DENI RAHMAT ◽  
LILIEK NURHIDAYATI ◽  
MARCELLA MARCELLA ◽  
ROS SUMARNY ◽  
DIAN RATIH LAKSMITAWATI
Keyword(s):  
Particle Size ◽  
Platelet Aggregation ◽  
Zeta Potential ◽  
Light Transmission ◽  
Hydroxypropyl Cellulose ◽  
Platelet Activity ◽  
Two Samples ◽  
Significant Difference ◽  
Aggregation Activity

Objective: The aim of the present study was to formulate bromelain into nanoparticles in order to improve its stability and activity. Methods: Crude bromelain was prepared by protein precipitation from the pineapple stem juice using ammonium sulphate at the concentration of 60% (w/v). Nanoparticles containing crude bromelain were generated using the ionic gelation method with hydroxypropyl cellulose–cysteamine (HPC-cysteamine) conjugate as a matrix. Crude bromelain was then added to the HPC-cysteamine solution for ionic interaction to construct the nanoparticles, which were then analyzed for their particle size and zeta potential. The resulting nanoparticles were mixed with adenosine diphosphate (ADP) to perform anti-platelet aggregation. Results: The nanoparticle had 928.3 nm in particle size and-7.25 mV in zeta potential. Anti-platelet activity of crude bromelain and the nanoparticles were determined with modification of light transmission aggregometry (LTA), in which ADP was used to induce an aggregation while a spectrophotometer UV-Vis was used to measure the absorbance at the wavelength of 600 nm. The result showed that crude bromelain and the nanoparticles rendered percentage inhibition of 8.00±1.17% and 48.56±11.19%, respectively. Conclusion: Based on the result of a one-way analysis of variance (ANOVA), it was concluded that there was a significant difference in percentage inhibition between the two samples. The nanoparticles demonstrated a better anti-platelet aggregation activity compared to crude bromelain.

Effect of Varying Wt% of TiC on Mechanical and Wear Properties of RZ5-TiC In-Situ Composite

2018 ◽  
Vol 8 (2) ◽  
pp. 45-56 ◽  
Author(s):  
Deepak Mehra ◽  
M.M. Mahapatra ◽  
S. P. Harsha
Keyword(s):  
Wear Resistance ◽  
Wear Behavior ◽  
Wear Test ◽  
X Ray Diffraction ◽  
Wear Properties ◽  
X Ray ◽  
Tic Particle ◽  
Mechanical And Microstructural Properties ◽  
Sliding Distance

The purpose of this article is to enhance the mechanical properties and wear resistance of the RZ5 alloy used in the aerospace application by adding TiC particles. The present study discusses processing of in-situ RZ5-TiC composite fabricated by self-propagating high temperature (S.H.S.) method and its wear behavior. The effects of TiC particle on mechanical and microstructural properties of the composite are studied. The wear test is performed by varying the sliding distance and applied load. The composite is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results exhibited the properties like strength and hardness of RZ5-10wt%TiC composite has been increased considerably, while grain size is decreased as compared to the RZ5 alloy. The fractography indicated mixed mode (quasi-cleavage and ductile feature) failure of the composites. The wear results showed improvement in wear resistance of the composite. The FESEM showed dominate wear mechanisms are abrasion, ploughing grooves.

scholarly journals Evaluation of Brain Targeting and Mucosal Integrity of Nasally Administrated Nanostructured Carriers of a CNS Active Drug, Clonazepam

2013 ◽  
Vol 16 (3) ◽  
pp. 456 ◽  
Author(s):  
Hend Mohamed Abdel-Bar ◽  
Amal Youssef Abdel-Reheem ◽  
Gehanne A.S Awad ◽  
Nahed Daoud Mortada
Keyword(s):  
Particle Size ◽  
Drug Release ◽  
Active Drug ◽  
Brain Targeting ◽  
Isopropyl Myristate ◽  
Safe Alternative ◽  
Integrity Assessment ◽  
Polyethylene Glycol 200 ◽  
Significant Difference

PURPOSE: The aim of the study was to target clonazepam, a CNS active drug, to the brain through the non-invasive intranasal (in) route using of nanocarriers with proven safety METHOD: in clonazepam nanocarriers were prepared by mixing isopropyl myristate, Tween 80, Cremophor EL or lecithin, polyethylene glycol 200, propylene glycol or ethanol in different ratios with water. in-vitro characterization of the nanocarriers was done by various methods including: polarized light microscopy, particle size determination, viscosity measurements and drug release studies. in-vivo study comparing intranasal and intravenous administration was performed. The drug targeting efficiency (DTE %) and direct nose to brain transport percentage (DTP %) were calculated and nasal integrity assessment was carried out. RESULTS: The obtained formulae had particle size below 100 nm favoring rapid direct nose to brain transport and the time for 100% drug release (T100%) depended on systems composition. Plasma Tmax of clonazepam nanostructured carriers varied from 10-30 min., while their brain Tmax did not exceed 10 min, in comparison with 30 min for iv solution. Although there was no significant difference (p>0.05) between the plasma AUC0-∞ of the different tested nanocarriers and intravenous one, the increase in brain AUC 0 -∞ of different nasal formulations in comparison to that of iv administration (3.6 -7.2 fold) confirms direct nose to brain transport via olfactory region. Furthermore, DTE and DTP% confirmed brain targeting of clonazepam following intranasal administration. CONCLUSION: The results confirmed that intranasal nanocarriers were proved to be safe alternative for iv clonazepam delivery with rapid nose to brain transport. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

scholarly journals Influence of Microstructure and Chemical Composition on Microhardness and Wear Properties of Laser Borided Monel 400

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5757
Author(s):  
Mateusz Kukliński ◽  
Aneta Bartkowska ◽  
Damian Przestacki ◽  
Grzegorz Kinal
Keyword(s):  
Wear Resistance ◽  
Laser Beam ◽  
Wear Test ◽  
Beam Power ◽  
Iron Particles ◽  
Wear Properties ◽  
Beam Scanning ◽  
Scanning Velocity ◽  
Monel 400 ◽  
Laser Beam Scanning

In this study, wear properties of Monel 400 after laser alloying with boron are described. Surfaces were prepared by covering them with boron paste layers of two different thicknesses (100 µm and 200 μm) and re-melting using diode laser. Laser beam power density was equal to 178.3 kW/cm2. Two laser beam scanning velocities were chosen for the process: 5 m/min and 50 m/min. Surfaces alloyed with boron were investigated in terms of wear resistance, and the surface of untreated Monel 400 was examined for comparison. Wear tests were performed using counterspecimen made from steel 100Cr6 and water as a lubricant. Both quantitative and qualitative analysis of surfaces after wear test are described in this paper. Additionally, microstructures and properties of obtained laser alloyed surfaces are presented. It was found that the wear resistance increased from four to tens of times, depending on parameters of the laser boriding process. The wear mechanism was mainly adhesive for surfaces alloyed with initial boron layer 100 µm thick and evolves to abrasive with increasing boron content and laser beam scanning velocity. Iron particles detached from counterspecimens were detected on each borided surface after the wear test, and it was found that the harder the surface the less built-ups are present. Moreover, adhered iron particles oxidized during the wear test.

High Power Diode Laser Clad Cu-WC-Ni Composite Coatings on Brass for Wear Resistance Enhancement

2013 ◽  
Vol 816-817 ◽  
pp. 47-53
Author(s):  
An Ru Yan ◽  
Zheng Wang ◽  
Zhi Yong Wang
Keyword(s):  
Electrical Conductivity ◽  
Wear Resistance ◽  
Diode Laser ◽  
High Power ◽  
Composite Coatings ◽  
Wear Test ◽  
Wear Properties ◽  
Ceramic Phase ◽  
Power Diode ◽  
High Power Diode Laser

To improve the wear resistance of brass substrate while retaining the electrical conductivity, laser cladding was applied to Cu-WC-Ni composite coating on brass using High Power Diode Laser. Microstructures, phase constitution and wear properties are investigated by means of scanning electronic microscopy with energy disperse spectroscopy and X-ray diffraction, as well as microhardness test and speed friction and wear test. The result shows that microhardness and wear resistance of clad coating were improved obviously compared with the brass substrate owing to the addition of WC ceramic phase, when the content of WC is 25%, the hardness of coating is 4 times of substrate, as well the cumulation mass loss is 1/19 of substrate. Electrical conductivity did not change as copper powder had high electrical conductivity.

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