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The purpose of this study was to evaluate the effect of the atmospheric pressure plasma treatment as a surface treatment method on the contact angle and shear bond strength (SBS) of zirconia ceramics and the failure mode between the self-adhesive resin luting agent and zirconia. The zirconia specimens were divided into eight groups based on the surface treatment method: alumina blasting, air plasma, argon plasma (AP), Katana cleaner, ozonated water, ozonated water+AP, Katana cleaner+AP, and tap water+AP. The contact angles, SBS, and fracture modes were tested. AP treatment significantly reduced the contact angle (p<0.0001). The combination of AP and other cleaning methods showed a higher bond strength and more mixed fractures. Our findings indicate that using atmospheric pressure plasma with argon gas, combined with other cleaning methods, results in a stronger bond than when using alumina blasting alone. [ABSTRACT FROM AUTHOR]

In this study, the reaction characteristics of reduction of calcined dolomite with ferrosilicon under argon flow to produce magnesium were studied by conducting experiments Pidgeon pellets were used to study the effect of reduced temperature, argon flow, and reduced time on the conversion of calcined dolomite reduction by ferrosilicon. The results show that the conversion significantly increases with the increase in the reduction temperature and reduction time. The conversion first increases and then decreases with the increase in argon flow. The highest conversion was obtained when the argon flow rate was 3 L·min−1, and a nearly spherical shape, nanoscale magnesium powder was obtained. Then the characters of the circulating argon entrainment process were numerically studied by ANSYS Fluent 17. A physical model of multilayer pellet arrangement was established, and a numerical calculation model of chemical reaction, radiation, heat conduction, and convection heat transfer was constructed. This confirms that high-temperature argon can effectively strengthen the heat exchange between pellets, improve the heat transfer efficiency, and facilitate the pellets to react quickly. When the conversion is 80%, the production efficiency increased by about 28.6%. In addition, the magnesium production efficiency showed an increase tendency with the increase of the argon inlet flow rate. [ABSTRACT FROM AUTHOR]

• Worldwide 1st time binder based 3D-printed (FGF) biodegradable Mg-based (MgGd-alloy) bone scaffolds. • Obtaining an as printed interconnected open porosity for cell ingrownth and vascularisation. • Mechanical behavior of experimental test and simulation shows good agreement. In this study, a binder based 3D-printing technology viz. Fused Granular Fabrication (FGF) technique was used to produce interconnected and open porous Mg-6.3Gd bone scaffolds for compression test analyses. The consolidation of the green parts (as printed scaffolds) was performed using solvent debinding in cyclohexane and subsequent conventional sintering in argon atmosphere. Compression tests were performed on as sintered parts. Additionally, a simulation strategy was developed for modeling the compression behavior of the sintered parts, utilizing the data from the experimental results. The experimental compression test results and the simulation strategy for the compression behavior of the 3D-printed scaffolds demonstrated good agreement. [Display omitted] [ABSTRACT FROM AUTHOR]

Palladium-silver (Pd–Ag) alloys are important as an alternative to gold-based alloys. The purpose of this study was to investigate the effect of an argon-arc vacuum pressure casting process on the recasting of the Pd–Ag alloy. The recasting Pd–Ag alloys were compared with conventional horizontal centrifugal (HC) casting to an argon (Ar)-arc vacuum pressure (Ar-arc/VP) casting. The first-generation castings were made from a Pd–Ag alloy purchased from a supplier. Next-generation castings were made from 50 wt% Pd–Ag alloy before casting and 50 wt% from previous castings. This sequence was repeated over three generations to form the 2nd, 3rd and 4th recasting ingots. The ingots were then measured for marginal accuracy, interfacial oxidation, hardness and phase identification. The recasting success rate of recastibility reached 100%. Compared with the HC group, the Ar-arc/VP group had better edge precision, smaller oxide layer thickness and lower hardness. The comparison of X-ray diffraction intensity showed that the relative intensities of Pd and Ag in the first, second and third generations recasting of the Ar-arc/VP group were significantly higher than those of the HC group. Phase analysis showed that the trace elements of indium and tin contents in the Pd–Ag recasting ingots of the Ar-arc/VP group were higher than those of the HC group. The results showed that the casting process used for recasting affected the quality of the Pd–Ag alloy. Therefore, Ar-arc/VP casting process could improve the effect of Pd–Ag recasting and maintain the alloy properties in comparison with HC casting. [ABSTRACT FROM AUTHOR]

In this article, we investigated the impact of a two electrodes argon atmospheric pressure plasma jet with a second grounded electrode (SGE) on the basil (Ocimumbasilicum) seeds germination rate. The SGE enhanced the axial electric field in the direction of the treated sample. The plasma operated with two current pulses per each halve a cycle of an applied voltage. The second plasma jet current pulsed increased from 0.7 mA to 3.6 mA and the emission of the O (777.2 nm) increased 3.85 times when the jet operated with the SGE compared to that operated without SGE. The germination rate increased by eight times at 5 min of exposure using the SGE. The SEM images proved a clear etching of the basil (O.basilicum) seed surface by plasma jet with more pronounced etching and cracks by using SGE specially at higher exposure times. [ABSTRACT FROM AUTHOR]

This paper presents a study of a novel type of magnetic nozzle that allows for three-dimensional (3-D) steering of a plasma plume. Numerical simulations were performed using Tech-X's USim® software to quantify the nozzle's capabilities. A 2-D planar magnetic nozzle was applied to plumes of a nominal pulsed inductive plasma (PIP) source with discharge parameters similar to those of Missouri S&T's Missouri Plasmoid Experiment (MPX). Argon and xenon plumes were considered. Simulations were verified and validated through a mesh convergence study as well as comparison with available experimental data. Periodicity was achieved over the simulation run time and phase angle samples were taken to examine plume evolution over pulse cycles. The resulting pressure, velocity, and density fields were analysed for nozzle angles from 0° to 14°. It was found that actual plume divergence was small compared to the nozzle angle. Even with an offset angle of 14° for the magnetic nozzle, the plume vector angle was only about 2° for argon and less than 1° for xenon. The parameters that had the most effect on the vectoring angle were found to be the coil current and inlet velocity. [ABSTRACT FROM AUTHOR]

[Display omitted] The effect of the process gas during laser powder bed fusion (L-PBF) was investigated using high-speed shadowgraphy while melting Ti-6Al-4V powder under high purity argon, helium, and a mixture of both, on a laboratory-scale machine. These recordings reveal that the generation of incandescent spatters can be reduced by at least 60% using pure helium and by ∼30% using addition of helium to argon in comparison to the use of traditional argon. The quantity of colder spatters appeared unaffected by the change of process gas. Different configurations of gas flow versus laser scanning direction were investigated and revealed that fumes and spatters are less accumulated at the laser spot with helium addition. Furthermore, the use of the argon–helium mixture proved to be as efficient as pure argon in the dragging and extraction of the fumes. Shadowgraphs revealed the more rapid expansion of fumes in helium-rich atmospheres, limiting the accumulation of scattering objects close to the laser spot and thus melt pool instability. These results were correlated to process snapshots on an industrial-scale system, confirming the reduction of hot spatter generation. Finally, the findings put in evidence the more rapid cooling of spatters with helium addition to the process gas – a promising aspect to limit powder bed degradation during L-PBF. In addition, the use of mixtures of helium and argon would be economically interesting compared to pure helium, typically more expensive than the traditionally used argon. [ABSTRACT FROM AUTHOR]

The silicothermic reduction of magnesium was investigated by the non-isothermal thermoanalysis in flowing argon, while the traditional investigations of silicothermic process for magnesium reduction were carried out under vacuum conditions. Firstly, the thermal gravimetric (TG) and derivative thermogravimetric (DTG) characteristic of briquettes prepared with calcined dolomite, ferrosilicon and fluorite were characterized by the thermogravimetric analyzer (TGA) at different heating rates. The intrinsic chemical kinetic mechanism was identified as a formal chemical reaction with the Nth order type which showed apparent activation energy E and reaction order n were 290.168 kJ mol−1 and 1.076, respectively. Then, a novel technique of magnesium production without vacuum was put forward and a three-dimensional unsteady numerical model incorporating the chemical reaction, radiation, heat conduction and heat convection was established and simulated, which was verified by Pidgeon process and novel technology. The numerical results showed that the cycle time of the novel technique could be reduced when the argon temperature was higher than 1343 K and the argon entrance velocity was over 0.05 m s−1. And the effect of the argon temperature on reduction degree was much larger than that of entrance velocity. [ABSTRACT FROM AUTHOR]

Purpose: The effects of argon laser (AL) irradiation exposure and remineralizing solution (RS) treatment were evaluated alone and in combination on caries-like lesion formation in permanent tooth root surfaces in an in vitro study. Materials and Methods: Ten caries-free permanent tooth root surfaces were divided into 4 segments and each segment from each tooth was assigned to 1 of 4 treatment groups: no treatment control (n = 10), AL irradiation alone at 13.5 J/cm² (0.270 W, 5-mm beam, 10 s, n = 10), RS treatment alone for 2 min (n = 10), and AL irradiation before RS treatment (n = 10). This allowed each tooth to serve as a matched internal control for each of the treatments. In vitro caries were created using a modified ten Gate solution. The longitudinal sections (3 per tooth segment, 30 per treatment group) were evaluated for mean lesion depth. Results: After lesion formation, mean lesion depths (± standard deviation) were 288 ± 32 μm for the no treatment controls, 198 ± 23μm for AL irradiation alone, 188 ± 19 μm for RS treatment alone, and 109 ± 14 μm for AL irradiation before RS treatment. All treatment groups had mean lesion depths that were significantly less than those for the matched no treatment control group (ANOVA, Duncan multiple range [DMR] test, p < 0.05). AL irradiation before RS treatment significantly reduced lesion depth compared with AL irradiation alone or RS treatment alone (ANOVA, DMR test, p < 0.05). Conclusion: Both AL and RS alone provided significant reductions in lesion depths for in vitro root surface caries compared with no treatment controls. However, the maximum reduction in caries-like lesion depth on permanent tooth root surfaces was achieved when the RS, containing calcium, phosphate, and fluoride in a carbopol base, was combined with AL irradiation. [ABSTRACT FROM AUTHOR]

The present paper describes a number of laser treatments of hard tissue lesions, including caries diagnosis by Nd:YAG and semiconductor lasers; caries treatment, including caries prevention, by argon, Nd:YAG, CO2, Er:YAG, and Er,Cr:YAGG lasers; removal of dentin caries by ruby, CO2, Nd:YAG, Er:YAG, and Er,Cr:YAGG lasers; and cavity preparation by Er:YAG and Er,Cr:YAGG lasers, including dental pulp response to the cavity preparation, treatment time until the end of cavity preparation, morphology of cavity margin and wall after cavity preparation, and microleakage and surface roughness of cavities. In addition, the morphological characteristics of alveolar bone after ablation by CO2, Er:YAG, Er,Cr:YAGG, and ArF excimer lasers are described. [ABSTRACT FROM AUTHOR]

There are many advantages to using the argon laser as a curing device in restorative dentistry. The right amount of light energy at the right wavelength is certain. Only one-fourth of the time is needed compared to VLC devices, a great advantage in the often stressful circumstances of private practices. Furthermore, due to better management of polymerization shrinkage with better marginal adaptations, better adhesion to the cavity walls and less microleakage results. Because of better physical properties, with a higher degree of conversion and less water absorption, there is better wear-resistance and less postoperative sensitivity. Due to a decrease in acid solubility and an increased caries resistance at the most critical point-the margin between filling and tooth structure-we obtain superior clinical results. [ABSTRACT FROM AUTHOR]

Research and clinical practice have shown that the argon laser can polymerize light-activated materials in less time (10 s or less) than the conventional halogen light and with equal or better physical properties. This article reviews the literature and presents clinical applications of polymerizing light-activated materials with the argon laser. A clinical case is also presented. [ABSTRACT FROM AUTHOR]

Rechargeable cells that rely on the stripping and plating of lithium during discharge and charge, respectively, must maintain smooth and flat lithium morphology to attain long cycle life. Higher surface area lithium metal, associated with dendrites or porous deposits, will increase the rate of reaction with liquid electrolyte, accelerate capacity loss, and decrease safety. Here we use argon BET to measure the specific surface area of lithium-metal electrodes as a function of cycle number. For "anode-free" cells with 1M LiPF6 in FEC:DEC electrolyte, the specific surface area of the lithium electrode increases by more than three times after 20 charge-discharge cycles. This measurement provides an assessment of degradation that can be linked to capacity loss and safety, which averages over the entire electrode and is therefore an excellent quantitative complement to SEM images used to look at lithium-morphology. [ABSTRACT FROM AUTHOR]

Molecular dynamics (MD) is used to investigate the combined effects of channel size and wall shear stress on force-driven Argon flows in nanochannels. The adaptive wall thermostat (AWT) is used to automatically adjust wall temperature refraining the viscous heating upsurge with the increased body force from increasing mean fluid temperature. AWT is functional up to "wall shear stress limit" (WSSL), classifying wall shear stress range into controllable and uncontrollable viscous heating ranges (CVH and UVH) before and beyond WSSL, respectively. With increasing wall shear stress in CVH, liquid Argon at ∼119.9 K exhibits more non-uniform temperature profile in larger channels. Consequently, further shear dependence of density profile and fluid molecular layering which leads to controversial size-dependent slip length. Within UVH, supercritical Argon emerges from the significant increase of temperature and pressure exceeding critical state; consequently, density profile and molecular layering decrease noticeably drifting toward walls which results in minor and proximate values of slip length in all channels approaching no-slip condition. The apparent viscosity is higher in larger channels with decreasing and increasing trends within CVH and UVH, respectively, associated with changing fluid state and phase. Finally, the continuum solution suggests the possibility of estimating the mass flow rate with reasonable accuracy relative to MD if implemented with appropriate properties and slip boundary condition. [ABSTRACT FROM AUTHOR]

Abstract The pore structure characteristics, such as porosity, pore size distribution, and pore connectivity, of tight gas sandstone are crucial for evaluating its reservoir capacity. However, due to multiscale pore size and various pore types in tight sandstone, the characterization of the pore structure can be optimized by combining the multiple fluid invasion methods. In this paper, optical microscopy (OM), gas injection porosimetry (GIP), helium pycnometry, low-pressure N 2 adsorption (LPN 2 A) and mercury intrusion porosimetry (MIP) were applied to investigate the pore structure characterization of tight sandstone from Sbaa Basin, Algeria. The results of OM observation suggest that the pores are composed of dissolution pores, intergranular pores, intragranular pores and microcracks. The porosity obtained by GIP and helium pycnometry is consistent, demonstrating the efficiency of GIP in measuring the porosity. Furthermore, after the small-sized pores (nanometer scale) and large-size pores (micrometer scale) of tight sandstone were investigated by using LPN 2 A and MIP respectively, it is noteworthy that the combination of the two methods is more appropriate to characterize the full scale of pore size distribution (PSD). The key point is to accurately integrate the measurements obtained from LPN 2 A and MIP for the estimation of the PSD from the dV/dlog(D) curves. The full scale of PSD proves that the pores are primary macropores if the IUPAC classification is adopted, which seems insufficient to reveal the storage capacity of the tight sandstone reservoir. Accordingly, the pores are more proposed to be classified into nanopores (1 nm - 1 μm), micropores (1–62.5 μm) and mesopores (62.5 μm - 4 mm), which is recommended by Loucks et al. (Loucks et al., 2012). Additionally, by comparing the permeability predicted from the inflectional pore throat and/or porosity with the measured permeability, it was found that the effect of the inflectional pore throat on the permeability is more remarkable than that of porosity. Highlights • Multiple fluid invasion methods were used to investigate the pore characters of tight sandstone. • The combination of LPN 2 A and MIP is more appropriate to characterize the full scale of pore size distribution. • It is not proper to classify the pore scale by IUPAC for this kind of tight sandstone. • The influence of inflectional pore throat on the permeability is more remarkable than that of porosity. [ABSTRACT FROM AUTHOR]

Graphical abstract An ab initio two-dimensional potential energy surface for Ar–N 2 O complex is developed. Theoretical results are in good agreement with the experimental data. Abstract A new potential energy surface for the Ar–N 2 O complex has been calculated using coupled-cluster singles and doubles calculations with a large basis set containing bond functions. A two-dimensional potential model was obtained by analytically fitting 315 points on the ab initio energy surface. The potential of the Ar–14N 2 O complex at an approximate T -shaped geometry, which has a global minimum of −216.449 cm−1 with R = 6.44 a 0 and θ = 88.13°, is reported. In addition, bound state energies up to J = 5 of the two isotopomeric, Ar–14N 2 O and Ar–15N 2 O, complexes were calculated. The calculated transition frequencies and spectroscopic constants are in good agreement with the experimentally observed results. [ABSTRACT FROM AUTHOR]

Objective Plasma of argon treatment was demonstrated to increase material surface energy leading to stronger and faster interaction with cells. The aim of the present in vitro study was to test the effect of plasma treatment on different graft materials. Materials and methods Synthetic hydroxyapatite (Mg-HA), biphasic calcium phosphate (BCP), cancellous and cortical xenogeneic bone matrices (CaBM, CoBM) were used representing commonly used classes of bone substitute materials. Fifty serially numbered disks with a 10 mm-diameter from each graft material were randomly divided into two groups: test group (argon plasma treatment) and control group (absence of treatment). Cell morphology (using pre-osteoblastic murine cells) and protein adsorption were analyzed at all samples from both the test and control group. Differences between groups were analyzed using the Mann–Whitney test setting the level of significance at p < 0.05. Results Plasma treatment significantly increased the protein adsorption at all samples. Similarly, plasma treatment significantly increased cell adhesion in all groups. Conclusions Data confirmed that non-atmospheric plasma of argon treatment led to an increase of protein adsorption and cell adhesion in all groups of graft material to a similar extent. Clinical relevance Plasma of argon is able to improve the surface conditions of graft materials. [ABSTRACT FROM AUTHOR]

In this study, the effect of argon as a co-contaminant in a CO 2 stream on interfacial tension, diffusion coefficients and storage capacity was experimentally determined under conditions relevant to carbon sequestration, using the pendant drop method. Interfacial properties affect primary capillary trapping mechanisms when CO 2 is injected since they set a limit to storage capacity in a geological formation. A strong increase in the isothermal interfacial tension at 45 °C and up to 20 MPa was observed with an increase in Ar co-contamination from 5 vol.% up to 100 vol.%. Since Ar content is present in small concentrations in most injected CO 2 streams, we focused on measuring brine-CO 2 interfacial tension and brine mixture (CO 2 and Ar) interfacial tension, with 5 vol.% and 10 vol.% of argon content at pressures from 7.5 MPa up to 40 MPa and in the temperature range from 40 °C to 80 °C, which has not previously been investigated and can be considered more oriented to real-world conditions for carbon sequestration. It was found that storage capacity decreased significantly from a scenario where pure CO 2 was injected, down to a scenario where 5 vol.% and 10 vol.% Ar were co-injected into the CO 2 stream. Additionally, the effect of other common impurities in CO 2 streams on interfacial properties and storage capacity is discussed. In order to evaluate the risk of CO 2 diffusion loss through a cap rock, we measured the diffusion coefficients of geological water in the injected fluid. It was found that the diffusion coefficients of water in Ar are higher in comparison to those of water in CO 2 . Small quantities of salt in water had a minor effect on the diffusion coefficients of brine in supercritical CO 2 . Experimentally obtained diffusion coefficients ( D ab ) were correlated to obtain the effective diffusion coefficient ( D eff ). It was found that, in the case of co-injection of Ar with CO 2 , the diffusive gas breakthrough could be enhanced. [ABSTRACT FROM AUTHOR]

Efficient exponential type basis sets constructed from new hyperbolic cosine type B functions have been used in self consistent field calculations for the ground states of the atoms from Helium to Argon and their ions. Different hyperbolic cosine type functions are incorporated into the B functions to increase the accuracy of atomic orbitals and correctly describe the electronic density of systems. The presented results for the minimal basis sets are shown that the quality of generalized hyperbolic cosine type B functions is one of the most appropriate basis sets of B functions, especially for increasing atomic number. A comparison with the standard B functions, hyperbolic cosine type B functions and the corresponding numerical Hartree-Fock values are given in tables. Our study shows that the modification of B functions can be an efficient way of increasing the accuracy of the atomic and molecular SCF calculations. These basis sets may also be used in the calculation of atomic properties such as cusp condition and density properties of atomic electrons. Some numerical results and comparisons are given to clarify the basis sets quality from the density point of view. An improved description of atomic orbitals based on the use of modified B functions will also play an important role in ion-atom collisions problems, semi-emprical and density functional methods. [ABSTRACT FROM AUTHOR]

The study focused on the effect of anoxic treatment on the discoloration of Prussian blue-dyed textiles and paper. Prussian blue pigment has been known to change color in the presence of light and heat in a vacuum for quite some time, but some claims were made that a low-oxygen environment alone contributed to its fading. The aim of this study was to determine whether argon anoxic treatment would induce the same changes when kept in the dark or in the light. The results clearly show that fading of Prussian blue in an argon anoxic condition occurs in the light but not in the dark. [ABSTRACT FROM AUTHOR]

Purpose: This study was carried out to investigate the microhardness of composite resin polymerized with three different light sources. Materials and Methods: Thirty cylindrical samples (6 × 2 mm) were divided into three groups as follows: G1, conventional light polymerization for 40 s at 600 mW/cm²: G2, soft-start polymerization for 40 s varying from 100 to 450 mW/cm² G3, argon laser irradiation for 10 s at 250 mW/cm². All samples consisted of a single layer of composite (Z100, 3M) and were stored in distilled water at 37°C ± 2°C for 24 h. Vickers microhardness tests were then conducted under 50 gf load for 15 s on the upper and lower surfaces of the samples. Data were submitted to two-way ANOVA and Tukey's test (5%). Results: ANOVA demonstrated significant differences of the main factors (light source and surface evaluated). The Tukey's test confirmed different treatment results (conventional: 115.50 ± 14.44 HVN; soft-start: 99.88 ± 10.63 HVN; laser: 70.11 ± 15.60 HVN) and surfaces evaluated: upper surface (conventional: 123.78 ± 9.69 HVN; soft-start: 109.38 ± 3.66 HVN: laser: 80.59 ± 12.10 HVN)/lower surface (conventional: 107.23 ± 13.93 HVN; soft-start 90.40 ± 5.01 HVN; laser: 59.63 ± 11.10 HVN). Conclusion: Laser irradiation resulted in lower microhardness values on both upper and lower surfaces compared to conventional light curing and soft-start polymerization with halogen light, while conventional and soft-start polymerization presented similar results. [ABSTRACT FROM AUTHOR]

In this work, argon flow within different microchannels with square cross-section is simulated by the molecular dynamics simulation (MDS) method. The first simulation is done within ideal microchannel and then, internal surfaces of this microchannel are roughened by cone, cubic and spherical barriers respectively to report influences of roughness with different geometries on the distribution of fluid flows. It is reported that cone and spherical geometry of barriers do not strongly affect flow characteristics of argon fluid within the microchannel, while the cubic geometry of barriers delays density distribution of argon flow in the middle region of the microchannel due to their destructive role against translocation of fluid particles between lateral and central layers of the microchannel. For the density results, it is reported that two physical phenomenon of thermal and external energies play important roles on the distribution of fluid particles in different sections of microchannel due to their different applying directions. Moreover, it is observed that the temperature profile of fluid flow within microchannel with cubic barriers touched a maximum temperature of 420 K at the central layers which are in the highest temperature level among all cases studied. Results of this study are applicable for practical application in small scale designs such as medical probes to inject destructive fluid for destroying tumors in cold surgeries. [ABSTRACT FROM AUTHOR]