Immersion Time Periods Research Articles

The influence of the water saturation on the strength of volcanic tuffs used as building stones

Moisture content is one of the most important factors influencing the strength of building stones. Ayazini and Seydiler (Afyonkarahisar, Turkey) tuffs were investigated with the goal to determine the influence of the water on their strength. Mercury porosimetry was used to determine the pore-size distribution. Ayazini tuffs have pore sizes ranging from about 200,000 to 10 nm and Seydiler tuffs ranging from about 7000 to 10 nm. The tuff samples are immersed in water with different time periods of 1, 6, 24 and 48 h. The following physico-mechanical properties were measured for all the samples both in dry and saturated condition: compressive strength and flexural strength. Test results were indicated by simple regression analysis; good correlations were found between physico-mechanical properties with dry and saturated tuff samples. The results had shown their mechanical strength decreases in wet conditions for dry samples tested had 22.21 MPa uniaxial compression strength while 1 h immersed samples had 15.11 MPa, which indicates a decrease of 31.96 %. After the 48 h water immersion time period, the value of compression strength decreases by 43.99 % and becomes 12.44 MPa.

Evaluation of Nickel Ion Release from Orthodontic Wires in Different Types of Artificial Saliva

Aims: To evaluate the amount of nickel ion release from stainless steel orthodontic wires in different artificial saliva and in different time periods. Materials and Methods: This study included six different commercial stainless steel orthodontic wires with different diameters. They were immersed in deionized water (control) and three different artificial saliva, the immersion periods included 7, 14, and 30 days. A graphite-furnace atomic absorption spectrometer (AAS) was used to determine the amount of nickel ions release. Results: The statistical analysis showed that there is a highly significance in the release of nickel ions for all types of wire except wires 0.18, and 0.16 x 0.22 which gave non-significant 2.45 and 1.37 respectively, and the time period of immersion had no significant effect in all types of wire. Conclusions: The release of nickel ions was influenced by the types of wire and the surface areas that in contact with immersion in solution, in addition to the composition of the orthodontic wires, but this were not proportional to the content of metal in the wire.

Tetrazolium test for viability estimation of Eugenia involucrata DC. and Eugenia pyriformis Cambess. seeds

The study aimed to adapt the tetrazolium test methodology to assess the viability of seed of Eugenia involucrata DC. (cherry) and E. pyriformis Cambess. (uvaia) freshly harvested and stored. Three lots of seeds of both species were used, being I (freshly harvested), II (stored for 15 days) and III (stored for 30 days). Seeds (lot I) of both species were immersed in distilled water for 24 hours and submitted to four preparation methods: whole seeds without seed coat and with ¾ of seed coat; longitudinally cut with and without seed coat (immersed in 0.1% tetrazolium for 4 hours). The most suitable preparation method was applied to the remaining lots, where three tetrazolium concentrations were tested: 0.075, 0.1 and 0.5% and three immersion time periods: 2, 4 and 6 hours. The tetrazolium test results were compared to the germination results. For the conduction of the tetrazolium test in seeds of both species we recommend soaking in distilled water by 24 hours and cut lengthwise on seeds with the seed coat. For cherry, the seeds should be immersed in 0.5% tetrazolium solution for 2 hours. For uvaia seeds, additional studies are recommended.

Environmental Effects on Mechanical Properties of Glass-Epoxy Composites

AbstractThis study presents the effects of seawater and distilled water immersion time periods on mechanical properties of unidirectional glass reinforced epoxy composites. Tension, compression, and shear test specimens exposed to seawater and distilled water were prepared according to ASTM standards. After tests, SEM imaging of fracture surface of specimens was made. Results showed that seawater and distilled water immersion time affects significantly mechanical properties and strength values of glass-epoxy composites.

Effect of staining agents on color change of composites

Composite resins are materials that can present color changing when exposed to pigments. Objective: The aim of this study was to evaluate, in vitro, the color changing of composites after immersion in different substances for different periods. Material and methods: Two microhybrid composite resins: Charisma (Heraeus – Kulzer) and Opallis (FGM) were used. Red wine and acai pulp were also used as immersion medium. For this study, 32 specimens with 10 mm of diameter and 2 mm of thickness were used, divided into 4 groups: Group 1 – Opallis composite immersed in red wine solution; Group 2 – Opallis composite immersed in acai berry pulp solution; Group 3 – Charisma composite immersed in red wine solution; Group 4 – Charisma composite immersed in acai berry pulp solution. The specimens were evaluated in the following time periods: T0 – baseline, T1 – 24 hours, T2 – 48 hours, T3 – 72 hours and T4 – 96 hours. For the assessment of staining, a spectrophotometer for colorimetry was used (Color Guide 45 / 0, PCB 6807 BYK-Gardner Gerestsried GmBH, Germany), and the values obtained were transferred to a computer and recorded according to CIELAB system. Results: The data were evaluated using Kruskal-Wallis non-parametric tests with the following ���ΔE mean values for � �the immersion periods of 24, 48, 72 and 96 hours, respectively: G1 – 7.35, 7.84, 9.04,10.48; G2 – 2.92, 4.15, 4.30, 4.64; G3 – 3.14, 7.35, 8.13, 8.43, G4 – 4.49, 5.99, 6.92, 6.76. Conclusion: Red wine showed a higher tendency toward altering the composite color than acai berry pulp. In addition, no significant difference was found concerning to the behavior of the two composite resins. Concerning to the immersion time periods, significant differences were only observed among the groups in the 24 hour time period.

Complementary Effects of Nanosilver and Superhydrophobic Coatings on the Prevention of Marine Bacterial Adhesion

A superhydrophobic coating composed of silver nanoparticles enclosed in multilayered polyelectrolyte films was deposited onto copper with the aim of preventing bacterial adhesion. Observations from scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that the amplified exponential growth of the multilayers could induce distinguishable, hierarchical micro- and nanostructures simultaneously. This growth caused the surface roughness to amplify in a lotus-leaf-like manner. UV/visible spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) confirmed the formation of well-dispersed Ag(0) nanoparticles (with sizes from 4-6 nm) in the films. SEM and fluorescence microscope images of the exposed surfaces revealed that the pattern of adhesion and the density of bacterial cells differed depending on the surface energy and the number of Ag(+) ions released during the various immersion time periods. The complementary effects of nanosilver and superhydrophobic coatings can help to effectively reduce bacterial adhesion and the formation of biofilms.

Wettability and Surface Tension of Amphiphilic Polymer Films: Time‐Dependent Measurements of the Most Stable Contact Angle

AbstractThe wettability of new amphiphilic block copolymer films is studied by measuring different types of water contact angles (static, receding, advancing, and most stable). The most stable contact angles are used to calculate the surface tensions of the films following the recently developed Marmur–Valal correlation. Most stable contact angles of water in an air‐in‐water system are also measured to study the changes in surface tension over relatively long periods of immersion time. The new approach yields surface tension values that are higher than those calculated by previous methods. The results suggest that reconstruction of the surface takes place at short time scale and continues to occur at long time scale. The responsive character of the polymer films can have implications for their use as biofouling release coatings.

Comparison of biodegradable behaviors of AZ31 and Mg–Nd–Zn–Zr alloys in Hank's physiological solution

The main challenge for the application of magnesium and its alloy as degradable biomaterials lies in their high degradation rates in physiological environment. In the present work, the biodegradable behavior of a patent magnesium alloy Mg–Nd–Zn–Zr (JDBM) and a reference alloy AZ31 was systematically investigated in Hank's physiological solution. The corrosion rate of JDBM (0.28 mm/year) was much slower than that of AZ31 (1.02 mm/year) in Hank's solution for 240 h. After corrosion products were removed, smooth surface of the JDBM was observed by SEM observation compared to many deep pits on the surface of AZ31. Open-circuit potential and potentiodynamic polarization results manifested that pitting corrosion did not occurred on the surface of JDBM at the early period of immersion time due to the formation of a more protective and compact film layer suggested by electrochemical impedance spectroscopy study. The corrosion rate of magnesium alloys was found to slow down in dynamic corrosion in comparison with that in the static corrosion. This provided the basis for scientific evaluation of in vitro and in vivo corrosion behavior for degradable biomagnesium alloy. The present results suggest that the new patent magnesium alloy JDBM is a promising candidate as degradable biomaterials and is worthwhile for further investigation in vivo corrosive environment.

The influence of chromium ions on the growth of the calcium hydroxyapatite crystal

Hydroxyapatite (Ca10(PO4)6(OH)2) is widely used as bio-ceramic materials and as adsorbents for separation of bio-molecules. These materials have also been used as adsorbents for heavy metals, supports and as catalysts in oxidation and dehydrogenation reactions. The catalytic performance of these materials depend on the lattice substitution of Ca sites in Hydroxyapatite structure by varied cations as Na, Mg, Sr and Mn, which result in changes in various structural pro perties as crystallinity and morphology. Pure calcium hydroxyapatite (S1) and Cr loaded hydroxyl apatite (S2, S3, S4 and S5) of different chromium concentrations have been prepared by wet precipitated method. An in-vitro examination is essential to investigate the mechanism of the deficient HA and tissue interface reaction by preparing SBF (Simulated Body Fluid) through the elemental and chemical analysis of Ca, P and Cr. FTIR used to analyze the samples after incubation in SBF for 24 day. PH of the samples also was measured at the first period of immersion time. At high loading of chromium ions, the formation of carbonate apatite decrease. The concentrations of the chromium in the Cr_HA crystal during the soaking in SBF are very safe dose for human.

Slow Crack Growth by Grain Boundary Dissolution of Hydroxyapatite in Water

Mechanical degradation of hydroxyapatite ceramics due to the slow crack growth was observed in water. Microstructural crack on the surface of hydroxyapatite initiated by grain boundary dissolution in liquid environment resulting in particle loosening and microstructural-level degradation, followed by a drastic decrease of mechanical properties. In this study, slow crack growth by the dissolution behavior of hydroxyapatite ceramics was investigated based on microstructural observation by field emission microscopy. The crack growth and morphological change of hydroxyapatite surface, especially at the initial stage of dissolution and related surface roughness were observed with immersion time. The surface dissolution occurred from the initial stage of immersion showing increase in surface roughness. Following certain period of immersion time, the surface dissolution initiated at grain boundaries and generated many separated grains.

Compatibility of tissue conditioners and denture cleansers: Influence on surface conditions

Chemical cleansing by denture cleansers is the first choice for denture plaque control of tissue conditioners. This study evaluated the influences of denture cleansers on the surface quality of tissue conditioners by determining surface roughness and porosity. Three tissue conditioners (Hydro-Cast, SR-Ivoseal, Visco-Gel) and 3 types of denture cleansers (Pika [enzyme type], Polident [neutral peroxide type with enzymes], Steradent [alkaline peroxide type]) were evaluated. Five specimens of each tissue conditioner/solution combination for each time period of immersion were prepared. The surface roughness of dental stone casts made from the tissue conditioners was evaluated using a profilometer. The surface quality of Hydro-Cast and Visco-Gel tended to be most deteriorated by the alkaline peroxide cleanser. The enzyme type of denture cleansers is most suitable for tissue conditioners in terms of surface quality. The suitable period for application of the enzyme cleansers would range from 3 to 7 days.

Application of Inhibitor‐Loaded Halloysite Nanotubes in Active Anti‐Corrosive Coatings

AbstractHalloysite particles are aluminum‐silicate hollow cylinders with a length of 0.5–1 µm, an outer diameter of ca. 50 nm and a lumen of 15 nm. These nanotubes are used for loading and sustained release of corrosion inhibitors. The inhibitor is kept inside the particles infinitely long under dry conditions. Here, halloysite nanotubes filled with anticorrosive agents are embedded into a SiOx–ZrOx hybrid film. An aluminum plate is dip‐coated and immersed into 0.1 M sodium chloride aqueous solution for corrosion tests. A defect in the sol–gel coating induces pitting corrosion on the metal accompanied by a strong anodic activity. The inhibitor is released within one hour from halloysite nanotubes at corrosion spots and suppresses the corrosion process. The anodic activity is successfully restrained and the protection remains for a long time period of immersion in NaCl water solution. The self‐healing effect of the sol–gel coating doped with inhibitor‐loaded halloysite nanotubes is demonstrated in situ via scanning vibrating electrode technique measurements.

Time-dependent Decalcifying Effects of Endodontic Irrigants with Antibacterial Properties

The aim of this study was to investigate the extent of calcium ion (Ca 2+) removal on root dentin after treatment with 1.25% NaOCl, 2.5% NaOCl, 5.25% NaOCl, 2% chlorhexidine (CHX), 2% iodine potassium iodide (IKI), and MTAD in 3 immersion time periods. Extracted human mandibular premolars were bisected longitudinally, and the root halves (n = 70) were isolated with nail varnish, leaving the root canal exposed. The specimens were immersed in the test solutions, during which the amount of Ca 2+ release into the solutions was determined at 5, 10, and 15 minutes by flame photometry. The decalcifying effect of 5%, 2.5%, and 1.25% NaOCl and 2% IKI significantly increased within time ( P < .05), with 5% NaOCl extracting the greatest amount of Ca 2+ at all treatment times. For 2% CHX and distilled water, a significant increase in the amount of Ca 2+ extraction from root dentin was only evident at 10 minutes ( P < .05) and did not change at 15-minute readings. Between the 5- to 10-minute and 10- to 15-minute intervals, the greatest amount of increase in the rate of Ca 2+ extraction from root dentin was observed in the 2.5% NaOCl group. At 15 minutes, 2% CHX and distilled water showed the least amount of change. Among the test solutions, MTAD extracted the least amount of Ca 2+ at 5 minutes.

Mineralization of Chitosan Membrane Using a Double Diffusion System for Bone Related Applications

Chitosan membranes were subjected to a pre-treatment in a double diffusion system, with a calcium solution in one chamber and a phosphate solution in the other chamber. Both chambers were separated by the chitosan membrane and subject to three mineralization periods (5, 10 and 15 minutes). After this pre-treatment the bioactivity of the different calcium phosphate coatings formed was tested for different periods of immersion time, 7, 14 and 21 days at room temperature and 37°C, in acellular simulated body fluid (1.0x). The results obtained demonstrated that the calcium phosphate coatings formed during the pre-treatment process are bioactive. It was found that the calcification is effective just in the side of the membrane exposed to the calcium solution chamber. This enabled to develop membranes with asymmetric osteoinductive properties that can be useful in different orthopedic applications.

A Study on the Effects of Immersion in River Water and Seawater on Blood, Saliva, and Sperm Placed on Objects Mimicking Crime Scene Exhibits

ABSTRACTResponding to the great demand for genotyping evidence obtained from underwater crime scenes or Items left in water, this study was undertaken to understand the kinetics of DNA degradation on different types of biological material immersed in water. In an attempt to recreate environments currently seen at crime scenes, various objects, stained with samples of blood, sperm, and saliva, were immersed at a depth of 5 meters in a river or the sea. The effect of water was assessed from six hours immersion to three months immersion. Immersion in water was clearly shown to be the main factor in DNA degradation. Moreover, the seriousness of this degradation mainly depends on the nature of the object on which the biological sample was placed. Substrates protecting the stain such as condoms, cigarettes butts or chewing gum enable the recovery of exploitable DNA profiles after up to three months submersion. For other kinds of evidence, the DNA degradation was directly related to the time period of immersion. As a result of this work, DNA analysts can improve the cost/effectiveness ratio with evidence seized from underwater crime scenes. These concerns may be less apparent with the use of miniSTRs.

The influence of steel surface modification by electrodeposited Zn–Fe alloys on the protective behaviour of an epoxy coating

The electrochemical and transport properties of epoxy coatings electrodeposited on steel and steel modified by Zn–Fe alloys were investigated during exposure to 3% NaCl. The Zn–Fe alloys were deposited on steel surface from alkaline bath galvanostatically using different current densities. From the time dependence of pore resistance of epoxy coating (impedance measurements), diffusion coefficient of water through epoxy coating (gravimetric liquid sorption measurements) and water content in the epoxy coating (thermogravimetric analysis), it was shown that Zn–Fe sublayer could improve the corrosion stability of the protective system based on epoxy coating. The values of the pore resistance were almost unchanged over the long period of immersion time for epoxy coating on steel modified by Zn–Fe alloy deposited by 4 A dm −2, indicating the great stability of this protective system. The values of diffusion coefficient of water through epoxy coating on this alloy and water content inside the epoxy coating were the smallest, indicating the low porosity of the coating.

The study of the attachment of a single-walled carbon nanotube to a self-assembled monolayer using X-ray photoelectron spectroscopy

A chemical approach was put forward to organize the randomly tangled single-walled carbon nanotubes (SWCNTs) on a gold surface. The SWCNTs were highly organized on gold, forming a monolayer structure. Angle-resolved X-ray photoelectron spectroscopy (ARXPS) was employed to study the spatial structure of the monolayer of SWCNTs. The adsorption kinetics of the nanotubes was studied by measuring the thickness of the samples prepared at different immersion times. It was found that a SWCNTs monolayer could not form for a short period of immersion time. When prepared for a long enough period of time, the well-ordered monolayer of SWCNTs could form and remain stable.

The effect of Zn-Ni sublayers on the corrosion behaviour and thermal stability of epoxy coatings electrodeposited on steel

The electrochemical and transport properties, as well as the thermal stability of epoxy coatings electrodeposited on steel and steel modified by Zn-Ni alloys were investigated during exposure to 3% NaCl. The Zn-Ni alloys were electrodeposited on steel using direct and pulse current. From the time dependence of the pore resistance of the epoxy coating (impedance measurements), the diffusion coefficient of water through the epoxy coating (gravimetric liquid sorption measurements) and the thermal stability of the epoxy coating (thermogravimetric analysis), it was shown that Zn-Ni sublayers significantly improve the corrosion stability of a protective system based on an epoxy coating. The values of the pore resistance were almost unchanged over a long period of immersion time for epoxy coatings on steel modified by Zn-Ni alloys, inidicating the great stability of these protective systems.

Effect of passivation on the dissolution behavior of Ti6A14V and vacuum-brazed Ti6A14V in Hank's ethylene diamine tetra-acetic acid solution Part I Ion release.

This work aims to investigate the effects of three factors, namely: (1) two differently prepared materials (as-polished Ti6A14V and 2 h brazed Ti6A14V); (2) three different surface passivation treatments (34% nitric acid passivation, 400 degrees C heated in air, and aged in 100 degrees C de-ionized water); and (3) periods of immersion time (up to 32 days), on trace element release in Hank's ethylene diamine tetra-acetic acid (EDTA) solution. After passivation and autoclaving treatment, the specimens were immersed in 8.0 mM EDTA in Hank's solution and maintained at 37 degrees C for periods of time up to 32 days. The 400 degrees C -treated specimens exhibit a substantial reduction in constituent release, which may be attributed to the higher thickness and rutile structure of the surface oxides. For acid-passivated and water-aged treatments, a highly significant decrease in the trace levels of Ti, A1, and V is detected from the brazed Ti6A14V compared to those obtained from the Ti6A14V specimens. It is hypothesized that an anatase-rutile transformation of surface TiO_2 is likely to occur, accelerated by the elements of copper and nickel in the brazed specimens. In addition, a significant time-related decrease in constituent release rate is observed for all kinds of specimens throughout the 0-8 day experimental period. The implication of the results is discussed.

フッ素徐放性シーラントを適用した際のエナメル質におけるフッ素の取り込みと耐酸性への効果について 第２報 シーラントの適用時間による違いおよびシーラント除去後における変化

The purpose of this study was to investigate the relationship between the amount of fluoride in the enamel, taken from a fluoride-releasing sealant (F + sealant) and acid resistance. The F + sealant was applied to the bovine enamel from 1 week to 6 months. After the removal of the F + sealant, the bovine teeth were immersed in phosphate buffer from 1 month to 6 months. At each time period, the enamel was biopsied with acid and its fluoride and calcium concentration were analyzed. Results were as follows: (1) It was suitable to immerse the teeth in 1M KOH solution for 2 days in order to remove the loosely bound fluoride produced by the fluoride application from the enamel. (2) The amount of fluoride in the surface enamel increased in proportion to the application time of F + sealant. (3) The amount of calcium dissolved from the enamel showed the significant decrease by the F + sealant application, while no difference was shown by the application time. (4) The amount of fluoride in the surface enamel acquired by the F + sealant was maintained for 6 months after the removal of the F + sealant. (5) The amount of calcium dissolved from the enamel showed no difference in the period of immersion time.