Cytotoxic Effect of Chitosan Nanoparticles on Normal Human Dental Pulp Cells

Introduction: Recent in vitro studies have shown that chitosan nanoparticles could enhance the antimicrobial activity of several dental materials. However, the biocompatibility of these nanoparticles with normal human cells is still controversial. The aim of this study was to evaluate the potential toxicity of various sizes and concentrations of chitosan nanoparticles cultured with normal human dental pulp cells. Methods: Normal human dental pulp cells were derived from human dental pulp tissues and cultured with (50-67) nm and (318-350) nm chitosan nanoparticles in concentrations: 0.2 mg/mL, 0.5 mg/mL, 1 mg/mL, and 2 mg/mL as study groups, and 0 mg/mL as a control. The cell attachment efficiency for each group was assessed at 16 hours. The proliferation rate and cell viability were evaluated at days 7 and 14. Both, attachment efficiency and proliferation rate were assessed by measuring the optical density of crystal violet stained cells. The cell viability was determined by the activity of the mitochondrial dehydrogenase enzyme. Statistical analysis was performed using One-Way ANOVA and post hoc Tukey test. Results: All concentrations of the (50-67) nm group significantly reduced cell attachment efficiency in comparison with the control (p<0.01) and with the (318-350) nm group (p<0.01). All concentrations of both groups, (50-67) nm and (318-350) nm, significantly reduced cell proliferation and cell viability compared to the control in dose-dependent and size-associated manners. (p<0.01). Conclusion: Chitosan nanoparticles exhibit a cytotoxic effect on normal human dental pulp cells

Three-dimensional boundary layer flow of nanofluids due to an unsteady stretching surface

A numerical solution has been obtained for the unsteady three-dimensional stretching flow and heat transfer due to uncertainties of thermal conductivity and dynamic viscosity of nanofluids. The term of nanofluid refers to a solid–liquid mixture with a continuous phase which is a nanometer sized nanoparticle dispersed in conventional base fluids. The unsteadiness in the flow and temperature fields is caused by the time-dependent of the stretching velocity and the surface temperature. Different water-based nanofluids containing Cu, Ag, and TiO2 are taken into consideration. The governing partial differential equations with the auxiliary conditions are converted to ordinary differential equations with the appropriate corresponding conditions via scaling transformations. Comparison with known results for steady state flow is presented and it found to be in excellent agreement.

Hydrocarbon Reservoir Evaluation: a case study of Tymot field at southwestern offshore Niger Delta Oil Province, Nigeria

Aim: This study presents the log analysis results of a log suite comprising gamma ray (GR), resistivity (LLD), neutron (PHIN), density (RHOB) logs and a 3D seismic interpretation of Tymot field located in the southwestern offshore of Niger delta. This study focuses essentially on reserves estimation of hydrocarbon bearing sands. Well data were used in the identification of reservoirs and determination of petrophysical parameters and hydrocarbon presence. Three horizons that corresponded to selected well tops were mapped after well-to-seismic tie. Structural depth maps were created from the mapped horizons. The structural style is dominated by widely spaced simple rollover anticline bounded by growth faults, and this includes down-to-basin faults, antithetic faults and synthetic faults. The petrophysical values – the porosity, net-to-gross, water saturation, hydrocarbon saturation that were calculated yielding an average porosity value of 0.23, water saturation of 0.32 and an average net-to-gross value of 0.62. Three horizons H1, H2 and H3 were mapped. The three horizons marked the tops of reservoir sands and provide the structures for hydrocarbon accumulation. Hydrocarbon in-place was estimated. The total hydrocarbon proven reserves for the mapped horizons H1, H2, and H3 were estimated to be 39.04MMBO of oil and 166.13BCF for sand E.

Experimental Progress of Semiconductor Nanomaterials

The research of semiconductor nanomaterials is the forefront of contemporary science and technology. Because ofits optical nonlinearity and luminescent properties diff erent from the bulk materials, it has great application prospectin the future optical switch, optical storage, light fast conversion and ultra-high speed processing. By arranging thecommonly used low-dimensional semiconductor nanomaterials preparation methods and methods of characterization,then compare them, it can helps to open up ideas and aids for in-depth thinking. In this paper, the preparation methodsof laser ablation, carbon nanotube template, molten salt, solution-liquid-solid method and template electrochemicalmethod are introduced. The characterization method is analyzed from particle size and morphology, composition andstructure analysis, surface interface analysis and several other aspects.

Application of Nanotechnology in Wastewater Treatment

Because the current social water pollution is serious, and the conventional method cannot eff ectively manage alltypes of water pollution, and its single eff ect cannot be satisfactory, we must seek new and eff ective treatment. Thepaper is a comprehensive review of the best practices of the conventional wastewater treatment method with referenceto the experiments and research results of nanotechnology in sewage treatment. Comparison of nanotechnology canbe compared with conventional methods to make the particles have a special function, and some special performancejust in the sewage treatment medium to a good effect: the depth of the catalytic method can be effective in thedecomposition of many types of organic pollutants such as halogenated hydrocarbons Class, chlorinated phenols,cyanide, various organic acids and can handle metal particles; adsorption method for the water heavy metal pollutiontreatment costs less, simple and widely used, nanofi ltration membrane can replace the adsorption and electrochemicalmethods, Pulping and precipitation are one of the most eff ective methods for the treatment of colloidal wastewater. Itcan eff ectively reduce the turbidity and chroma of waste water, remove a variety of macromolecular organic matter andsome heavy metal ions ( Mercury and lead); organic / inorganic composite nanoparticles with its excellent inorganicmaterials, light, electricity, magnetic and other properties, organic materials, excellent processing performance,biocompatibility, for many diffi cult to deal with water pollution control, which has a corresponding method, can besimple and eff ective to solve the problem. The application of nanotechnology in water treatment has shown a broadprospect, but needs further research and improvement.

Advances in Application of Nanomaterials in Life Science

Nanomaterials had attracted much attention since their discovery with their unique structure, peculiar physical,chemical, mechanical properties and potential application prospects. In the past few years, the theoretical andexperimental research on biological nanomaterials has become the focus of attention, especially the biochemistry,biophysics, biomechanics, thermodynamics and electromagnetism of nucleic acid and protein, while its intelligentcomposites have become the forefront of life science and materials science. At present, nano-bio-chip materials,biomimetic materials, nano-motors, nanocomposites, interface biomaterials, nano-sensors and drug delivery systemshave made great progress. In this paper, the characteristics of these materials, research and development of theapplication were reviewed, a brief overview of the nano-materials in the life sciences of the main applications, and toexplore the development prospects of biological nano-materials.

Application of Nanotechnology in Post-treatment of Automobile Tail Gas Nitrogen Oxides

Nano-catalyst has a very high catalytic activity and has a good prospect in automobile exhaust gas purifi cation. Thispaper summarizes the research status of nano-scale automobile exhaust gas purifi cation catalytic materials in recentyears, focusing on the analysis of the structure and performance of several components in the tail gas catalyst afternano-scale, and discusses its existing problems and application trends.

Preparation of Cage Nanoporous Silica and Its Application in Chromatographic Fillers

In this paper, the cage nanoporous silica is composed of ethyl orthosilicate as silicon source, triblock copolymerpoly (ethylene oxide) -poly (propylene oxide) -polyethylene oxide (F127) as structure guide agent and additive, whilethe Fm3m cubic structure of cage type nanoporous silica was prepared by hydrothermal synthesis method. It is easyto control the self-assembly of the silica triblock copolymer intermediates thermally. In addition, the change in samplepore size and pore volume can be achieved by a hydrothermal reaction at a temperature of 100 ° C to 150 °C. Smallangle X-ray diff raction shows that these samples have ordered pores, while adsorption studies show that they havehigh porosity, uniform distribution of bimodal pores and large pore volume. Use separation of p-methylbenzene borate,iodobenzene and biphenyl by using three kinds of cage-type nanoporous silica materials as chromatographic fi llers. Theresults showed that the material prepared at 130 ℃ under hydrothermal condition had the best eff ect on the separationof three organic compounds.

Optimization of Heat-Dried Silane Application for CAD/CAM Ceramic Resin Bonding

Purpose. Evaluate surface treatments and silane application methods and their effect on shear bond strength (SBS) before and after aging. Materials and methods. Slices of IPS e.max CAD and Vitablocs Mark II, were embedded in acrylic resin. The block was randomly assigned to 5 groups; E:etching with hydrofluoric acid (HF), rinsing, followed by cleaning in ultrasonic bath; E/S:HFetching and cleaned as group E followed by silane application for 20s, air drying and hot drying; E/S+:HFetching and cleaned as group E, followed by silane application for 60s, air drying and hot air drying, rinsing with boiling water and hot air drying; S:silane application for 20s followed by air drying and hot air drying; S+:silane application for 60s followed by air drying, air drying and hot air drying, rinsing in boiling water and hot drying. Cylinders of composite resin (n=12) were bonded with adhesive. SBS testing was carried out after 24h or after thermocycling for groups E; E/S and E/S+. Results. For 24h SBS showed significantly higher mean bond strength with E/S, for both ceramic, compared to E and E/S+. The use of silane alone showed significantly lower mean bond strength. No significant differences were found between E/S and E/S+ for VITA. The SBS was negatively affected by simulated aging in E/S group and positively in E/S+. Conclusions. The association of HFetching and a heat-dried silane showed to be significant to obtain a high SBS. Furthermore, the optimized silane application is not relevant to the immediate SBS while it enhances after aging.

Synthesis of 2,3-dihydroquinazolin-4(1H)-ones catalyzed by Perchlorated Zirconia (HClO4/ZrO2) nanoparticles as a novel solid acid catalyst

Zirconia was synthesized in nanosize by sol-gel method and perchlorated zirconia (HClO4/ZrO2) with various calcination temperatures were prepared and characterized by XRD, FTIR and SEM techniques. The catalyst acidity characters, including the acidicstrength and the total number of acid sites were determined by potentiometric titration. The catalytic performance experiments show that the HClO4/ZrO2 with calcination temperature of 300 °C has the best catalytic activity. 2,3-Dihydroquinazolin-4(1H)-ones wereprepared in good to excellent yields via condensation reaction of oaminobenzamide and various types of aldehydes and ketones in the presence of HClO4/ZrO2 nanoparticles as an efficient solid acid catalyst. The catalyst is reusable with moderate loss in activity.