Presence Of Fines Research Articles

Microstructure, Mechanical Properties and Corrosion Performance of Laser-Welded NiTi Shape Memory Alloy in Simulated Body Fluid.

Laser-welding is a promising technique for welding NiTi shape memory alloys with acceptable tensile strength and comparable corrosion performance for biomedical applications. The microstructural characteristics and localized corrosion behavior of NiTi alloys in a simulated body fluid (SBF) environment are evaluated. A microstructural examination indicated the presence of fine and equiaxed grains with a B2 austenite phase in the base metal (BM), while the weld metal (WM) had a coarse dendritic microstructure with intermetallic precipitates including Ti2Ni and Ni4Ti3. The hardness decreased from the BM to the WM, and the average hardness for the BM was 352 ± 5 HV, while it ranged between 275 and 307 HV and 265 and 287 HV for the HAZ and WM, respectively. Uni-axial tensile tests revealed a substantial decrease in the tensile strength of NiTi WM (481 ± 19 MPa), with a reduced joint efficiency of 34%. The localized corrosion performance of NiTi BM was superior to the WM, with electrochemical test responses indicating a pitting potential and low corrosion rate in SBF environments. The corrosion rate of the NiTi BM and WM was 0.048 ± 0.0018 mils per year (mpy) and 0.41 ± 0.019 mpy, respectively. During welding, NiTi's strength and biocompatibility properties changed due to the alteration in microstructure and formation of intermetallic phases as a result of Ti enrichment. The performance and safety of welded medical devices may be impacted during welding, and it is essential to preserve the biocompatibility of NiTi components for biomedical applications.

Behaviour of sand under the constant shear drained stress path: the role of fines

This paper presents a specifically designed experimental study aimed at exploring the role of fines in altering the behaviour of sand under the constant shear drained (CSD) stress path. The novelty of this study includes that the interplay of several key factors (fines shape, fines content, void ratio) was investigated systematically and the true constant shear stress condition was fulfilled by means of an advanced servo system which allowed the entire loading response to be captured. One of the marked findings is that the presence of fines not only alters the onset of instability of loose sand but also affects the deformation development thereafter. Drained instability can be triggered more easily in loose sand mixed with silica fines compared with the sand on its own. At the same quantity of fines, instability can be triggered more easily for sand mixed with rounded fines. However, the effect of fines appears to be marginal for sand at dense state. For all tested specimens, values of the axial strain rate at instability fall in a narrow range (0.008%/min–0.016%/min), meaning that the axial strain rate can be potentially a useful guide for quantitatively determining the inception of instability under the CSD conditions. The stress ratio q/p′ at onset of instability under the CSD conditions is also state dependent as under the undrained conditions.

Model of Formation of Gold-Bearing Placers in Platform Areas (East of the Siberian Platform)

A model of the formation of gold-bearing placers for platform areas is proposed for the first time. Placers on the platforms are formed mainly due to the Precambrian ore sources spatially confined to the basement outcrops, and, locally, Mesozoic, formed when tectonic-magmatic activation occurs in the zones of paleorifts and deep faults. Placers formed due to the Precambrian sources are characterized by the presence of fine and thin gold with a size of 0.1‒0.25 mm and, as a rule, are not of commercial interest. They bar alluvial and coastal-marine allochtonous placers and are considered as complex, with associated mining of titanium, zirconium and other useful components. Placers formed due to the sources of the Mesozoic stage of ore formation belong to the class of small and medium reserves, the size of gold in them ranges from dust-like to 0.2‒0.25 mm or more and they are usually mined by prospectors' team. Placers on the platforms do not form sheet deposits, since they are formed mainly due to sources of non-placer-generating formations. The presence of such placers indicates the proximity of the ore occurrence, which the type and location can be determined based on the study of the mineralogical and geochemical features of the placer gold itself.

Influence of fine content on undrained monotonic behavior of carbonate sand

The behavior of carbonate sand is different from that of siliceous sand in terms of high compressibility and crushability, specific particle shape, and physical properties. Thus, investigating the behavior of these soils is of great importance because of their prevalence in coastal areas. Nevertheless, a few studies have considered the presence of fines in the mixture with carbonate sand. The present study explores the influence of non-plastic fines on the undrained monotonic behavior of Bushehr carbonate sand. For this purpose, 30 undrained monotonic triaxial tests were performed on carbonate sand with silt ranges of 0% to 40% with two different void ratios. According to the results, the undrained shear strength of carbonate sand diminished with the addition of silt percentage up to 20%, and increased dramatically at 30% silt content. Also, the results of 40% silty sand revealed that this sample is stronger than samples with 10% and 20% silt content. By surveying the location of the phase transformation point in samples, it was observed that silt particles reduce the dilative phase. Also, confining pressure intensified the contractive phase while relative density had the opposite effect. The results showed that the effect of particle breakage is negligible in this study.

Hookworm – Related cutaneous larva migrans: Case report

Hookworm-related cutaneous larva migrans is caused by the intradermal migration of soil-dwelling filariform larvae of dog and cat hookworms, most commonly Ancylostoma, usually develop itchy skin lesions, usually consisting of migrating superficial serpiginous traces, or sometimes stationary follicular eruptions. The plantar topography or on the regions of the body in contact with the sand of the beaches of the Antilles, West Africa and East Asia, the presence of fine and not very mobile serpiginous furrows and eczematization with vesiculobullous eruption, are characteristic. There are misleading profuse forms such as pseudo-folliculitis. We present a Moroccan patient who developed the disease after their return from and who responded well to treatment with albendazole.

Effect of 10% recycled sands from various storage sites on the mortar’s properties

This study investigates the effects of using 10% of recycled sand in mortars. Using the concrete equivalent mortar approach, the reference mortar was developed from a flowable natural aggregate concrete with a C35/45 strength class. Five mortars were manufactured by replacing 10% of the natural sand with recycled sand from various recycling platforms while keeping the formulation parameters constant. The fresh state results showed that recycled mortar had an increased air content, which increased yield stress and viscosity. In addition, mortars containing 10% recycled sand showed a faster rate of flow loss over time. There was no difference between the materials in the hardening state with regard to the evolution of the hydration heat or the setting time. The relationship between the qualities of mortars and sands revealed that the air content depends on the sand’s fineness and the presence of fines with a diameter less than 63 µm. A relatively small increase in porosity and water absorption capacity was observed with a decrease in the compressive and flexural strength with no obvious change in the elastic modulus. The total shrinkage was revealed to depend on the fines content and decreases when the fines content increases.

Influence of ambient gas on self-reversal in Li transitions relevant to isotopic analysis.

Laser induced breakdown spectroscopy is a promising, rapid analysis method for the detection and quantification of Li and its isotopes needed in geochemical, nuclear, and energy storage applications. However, spectral broadening in laser produced plasmas, presence of fine and hyperfine structures, and self-reversal effects make Li isotopic analysis via laser induced breakdown spectroscopy challenging. The present study explores the influence of Ar, N2, and He ambient gases over the pressure range of 0.05 - 100 Torr on line broadening and self-reversal of the Li I transition with the greatest isotopic shift in the VIS spectral region (i.e., ≈670.8 nm, ≈15.8 pm isotopic shift). We perform spatially and temporally resolved optical emission spectroscopy of plasmas produced via laser ablation of LiAlO2 substrates. Our results show that the self-reversal and linewidth is reduced at lower pressures for all gases, and using optimized plasma conditions with chemometric methods, the 6Li/7Li isotopic ratios can be predicted.

Freeze-thaw behavior of geocell-reinforced bases considering different fines contents

Freeze-thaw (F-T) cycles are a major cause of pavement distress in seasonal frost regions, and the presence of fines in bases can accelerate the pavement degradation induced by cyclic freeze and thaw. Among countermeasures used to mitigate the F-T induced damages in pavements, geocell-reinforced bases can be an effective solution in mitigating F-T damage to cold region roads. However, there is almost no research dedicated to understanding the potential benefit of geocells and the underlying mechanisms in this regard. This study employed a custom-made model test device to investigate the F-T performance of geocell-reinforced sands considering different fines contents. The experimental results showed that the increase in fines content substantially increased the peak heave and thaw settlement and decreased the stiffness and ultimate bearing pressure. The application of geocells reduced the peak heave and thaw settlement by 11–18% and 22–35%, respectively, but this benefit was negligible at high kaolin content (12%). The use of geocells increased the stiffness and ultimate bearing pressure by about 43–90% and 41–73%, respectively, after five F-T cycles. The findings of this study are relevant to the design of geocell-reinforced bases under F-T cycles and advance the understanding of the underlying mechanisms.

The Influence of Grain Size Distribution on Laboratory‐Generated Volcanic Lightning

AbstractOver the last decades, remote observation tools and models have been developed to improve the forecasting of ash‐rich volcanic plumes. One challenge in these forecasts is knowing the properties at the vent, including the mass eruption rate and grain size distribution (GSD). Volcanic lightning is a common feature of explosive eruptions with high mass eruption rates of fine particles. The GSD is expected to play a major role in generating lightning in the gas thrust region via triboelectrification. Here, we experimentally investigate the electrical discharges of volcanic ash as a function of varying GSD. We employ two natural materials, a phonolitic pumice and a tholeiitic basalt (TB), and one synthetic material (soda‐lime glass beads [GB]). For each of the three materials, coarse and fine grain size fractions with known GSDs are mixed, and the particle mixture is subjected to rapid decompression. The experiments are observed using a high‐speed camera to track particle‐gas dispersion dynamics during the experiments. A Faraday cage is used to count the number and measure the magnitude of electrical discharge events. Although quite different in chemical composition, TB and GB show similar vent dynamics and lightning properties. The phonolitic pumice displays significantly different ejection dynamics and a significant reduction in lightning generation. We conclude that particle‐gas coupling during an eruption, which in turn depends on the GSD and bulk density, plays a major role in defining the generation of lightning. The presence of fines, a broad GSD, and dense particles all promote lightning.

Influence of fines on the monotonic and cyclic shear behaviour of volcanic soil “Shirasu”

Drained and undrained monotonic and undrained cyclic triaxial tests have been carried out on reconstituted samples of Shirasu originally deposited from pyroclastic flows in the Kagoshima area, Japan. This material contains 20%–30% fines derived from the same minerals as the coarse grains. Well-graded fines can form a weakly interlocked structure in loose Shirasu separating the coarse grains and resulting in a weak liquefiable soil. In order to clarify the mechanical characteristics of Shirasu, a series of triaxial tests were carried out on the original Shirasu and a material whose fines had been washed out. The “fines” Shirasu was weak with its properties highly dependent on the confining stress while the “no-fines” Shirasu had a high strength which decreased with increasing confining stress due to breakage of asperities. The presence of fines between coarse grains altered the location of critical state line of Shirasu. Under undrained cyclic loading and low confining pressures, the weakly interlocked structure of medium-dense “fines” Shirasu collapsed resulting in contractive behaviour and liquefaction. As the confining pressure was increased, this weak fine structure was compressed and the soil structure became stiffer under cyclic loading. In practical terms, this means that Shirasu which is placed as a loose hydraulic fill will be prone to liquefaction. The undrained cyclic response of medium-dense “no-fines” Shirasu was similar to that of dense “fines” Shirasu. Thus, the removal of fines was equivalent to compacting the material to a relatively high density.

Granular fertilizer caking: A research on the performance evaluation of coating agents

Caking formation in fertilizer products during handling and storage is a frequently encountered problem. Caked fertilizers become together as lumps, lose their free- flowing properties, and create inefficient applications. Several parameters such as relative humidity and temperature of the environment, pressure by pile height, and physicochemical properties of fertilizer product such as moisture content, presence of fines and chemical composition, etc. cause or accelerate caking mechanism. Internal or external anticaking products have been proved to be effective in preventing the caking of fertilizer particles. Liquid or wax anticaking agents are applied externally as coatings on the fertilizer surface. This study focuses on the performance evaluation of commercially available liquid- wax anticaking agents coated on NP 20-20-0 fertilizer, classified as three main groups: petroleum-derived, alkyl amine-fatty acid containing mixtures and bio- based composition. Caking performance of coating products are evaluated via small-bag storage test in 4 sets, according to the results, petroleum derived and alkyl amine- fatty acid containing anticaking products show similar performance, whereas bio-based products’ performance is moderate. This study focuses on a practical approach that will help fertilizer industry about which type of coating product will be effective on the anticaking properties of nitrogenous fertilizers and gives brief results of the effect of commercially available products with various ranges of chemical composition on the caking process.

The Mechanical Response of a Silty Sand Stabilized with Colloidal Silica

This paper presents a laboratory investigation into the mechanical response of a silty sand, with a fines content of 10%, stabilized with colloidal silica (CS). To this end, a series of unconfined compression tests as well as monotonic and cyclic triaxial tests was performed on a silty sand, comprising a mixture of a clean sand and a silty sand, stabilized with two concentrations of CS. The effect of various parameters on the behaviour of the stabilized silty sand was studied, such as CS concentration, soil density, and the presence of fines. The test results were compared with the corresponding of the untreated silty sand as well as the parent clean sand. It is shown that stabilization, even at the lowest CS = 6% concentration studied, significantly improves the undrained shear strength as well as the liquefaction resistance of the stabilized silty sand. Both the monotonic and cyclic response of the stabilized soil are only slightly affected by density. Furthermore, cyclic straining up to at least 5% of double-amplitude axial strain does not influence the undrained shear strength of the stabilized silty sand.

Impact of Powder Properties on the Rheological Behavior of Excipients.

With the emergence of quality by design in the pharmaceutical industry, it becomes imperative to gain a deeper mechanistic understanding of factors impacting the flow of a formulation into tableting dies. Many flow characterization techniques are present, but so far only a few have shown to mimic the die filling process successfully. One of the challenges in mimicking the die filling process is the impact of rheological powder behavior as a result of differences in flow field in the feeding frame. In the current study, the rheological behavior was investigated for a wide range of excipients with a wide range of material properties. A new parameter for rheological behavior was introduced, which is a measure for the change in dynamic cohesive index upon changes in flow field. Particle size distribution was identified as a main contributing factor to the rheological behavior of powders. The presence of fines between larger particles turned out to reduce the rheological index, which the authors explain by improved particle separation at more dynamic flow fields. This study also revealed that obtained insights on rheological behavior can be used to optimize agitator settings in a tableting machine.

Elucidating the Effect of Fine Lactose Ratio on the Rheological Properties and Aerodynamic Behavior of Dry Powder for Inhalation.

Dry powder inhaler (DPI) is recognized as the first choice for lung diseases' treatment. However, it lacks a universal way for DPI formulation development. Fine lactose is commonly added in DPIs to improve delivery performance; however, the fine ratio-dependent mechanism is unclear. Therefore, the objective of this study is to explore the influence of fine lactose ratio on DPI powder properties and aerodynamic behavior, and the fine lactose ratio-dependent mechanism involved during powder fluidization and lung deposition. Here salbutamol sulfate was used as a model drug, Lactohale® 206 as coarse carrier, and Lactohale® 300 as fine component; the mixtures were prepared at 1% drug content, with fine content up to 20%. It was shown that with the fine addition, flowability of the mixtures was improved, interaction among particles was increased, and the presence of fines could help to improve DPI's aerosolization performance. When the fines added were less than 3%, the "active site" hypothesis played a leading role. When the added fines were over 3% but less than 10%, fluidization enhancement mechanism was more important. After the added fines reaching 10%, aggregate mechanism started to dominate. However, FPF cannot be further increased once the fines reached 20%. Moreover, the correlations between FPF and dynamic powder parameters were verified in ternary mixtures, and cohesion had a greater impact on FPF than that of flowability. In conclusion, adding lactose fines is an effective way to improve lung deposition of DPI, with the concrete mechanism lactose fine ratio dependent.

Honesty pledges for the behaviorally-based regulation of dishonesty

ABSTRACT A common regulatory dilemma is determining how much trust authorities can place in people’s self-reports, especially in contexts with an incentive to cheat. In such contexts, regulators are typically risk averse and do not readily confer trust, resulting in excessive requirements when applying for permits, licenses, etc. Studies in behavioral ethics have suggested that asking people to ex-ante pledge to behave ethically can reduce their level of dishonesty and noncompliance. However, pledges might also backfire by allowing more people to cheat with no real sanctions. Additionally, pledges’ effects have almost always been studied in one-shot decision making without sanctions. We explore pledges’ potential effects by manipulating whether pledges were accompanied by sanctions (fines) and testing their impact on sequential, repeated ethical decisions. We find that pledges can considerably and consistently reduce dishonesty, and this effect is not crowded out by the presence of fines. Furthermore, pledges also affect “brazen liars” who cheat to a large extent and also those who score low on tendency to follow rules and norms. We conclude that pledges could be an effective tool for the behavioral regulation of dishonesty, to reduce regulatory burden, and to build a more trusting relationship between government and the public.

Improvement of Mechanical Strength of a Hot-Worked Twinning-Induced Plasticity Steel through an Optimum Secondary Annealing Treatment

The microstructure of the twinning-induced plasticity (TWIP) steel microalloyed by Ti (TWIP-Ti) exhibited a wide grain size distribution after applying a thermomechanical treatment. The presence of fine and coarsest grains affected mechanical twinning and properties. This research was directed toward elucidating the effect of an optimum secondary annealing treatment to produce a homogenous microstructure through the release of remnant energy stored during the hot deformation processing of a TWIP-Ti steel. A comprehensive analysis of the effect of annealing parameters on the microstructure and its enhanced mechanical properties in terms of grain size distribution, precipitation strengthening and annealing twin fraction was performed. The microstructural characterization included light optical microscopy and scanning electron microscopy (SEM). SEM line scans were performed to characterize precipitate particles found in the TWIP-Ti steel. Microhardness and tensile tests were performed on the base material (as-solution condition) and post-annealing samples. The Taguchi method was applied to optimize the annealing parameters. Furthermore, image processing was employed to quantify the grain size distribution and annealing twin fraction. The analysis results revealed that upon completion of the second stage of annealing treatment with the optimal parameters, the grain size heterogeneity decreased due to the effect of coarsest grain subdivision. The low SFE of the TWIP-Ti steel, homogenous grain size microstructure and precipitation strengthening produced yield strength and ultimate tensile strength increases of 27% and 8.5%, respectively. The homogenous grain size distribution had a more substantial effect on improving the mechanical properties than the annealing twin fraction.

Factors Motivating Farmers for Collective Action for Management of Irrigation System in Nepal

The study analyzed the factors motivating the farmers for collective action for the management of the Shardikhola Puranchaur Irrigation System of the Kaski district of Nepal in 2019. A cross-sectional data of 184 farmers were collected using a simple random sampling method. A logit regression was used for data analysis. Age of the household head, years of schooling of the household head, presence of fine in monetary terms, number of farmers in a branch of the irrigation system positively motivated farmers in the involvement in the group for the management of the irrigation system. Motivation among farmers for collective action for management of the irrigation system was influenced by a combination of different factors. Therefore, the proper distribution of water at different branches, binding every level of users by law and transparency in the use of the income of the irrigation system must be maintained to achieve the desired results.
 Int. J. Soc. Sc. Manage. Vol. 8, Issue-1: 285-291

Characteristics of Pulmonary Auscultation in Patients with 2019 Novel Coronavirus in China

Background: Effective auscultations are often hard to implement in isolation wards. To date, little is known about the characteristics of pulmonary auscultation in novel coronavirus (COVID-19) pneumonia. Objectives: The aim of this study was to explore the features and clinical significance of pulmonary auscultation in COVID-19 pneumonia using an electronic stethoscope in isolation wards. Methods: This cross-sectional, observational study was conducted among patients with laboratory-confirmed COVID-19 at Wuhan Red-Cross Hospital during the period from January 27, 2020, to February 12, 2020. Standard auscultation with an electronic stethoscope was performed and electronic recordings of breath sounds were analyzed. Results: Fifty-seven patients with average age of 60.6 years were enrolled. The most common symptoms were cough (73.7%) during auscultation. Most cases had bilateral lesions (96.4%) such as multiple ground-glass opacities (69.1%) and fibrous stripes (21.8%). High-quality auscultation recordings (98.8%) were obtained, and coarse breath sounds, wheezes, coarse crackles, fine crackles, and Velcro crackles were identified. Most cases had normal breath sounds in upper lungs, but the proportions of abnormal breath sounds increased in the basal fields where Velcro crackles were more commonly identified at the posterior chest. The presence of fine and coarse crackles detected 33/39 patients with ground-glass opacities (sensitivity 84.6% and specificity 12.5%) and 8/9 patients with consolidation (sensitivity 88.9% and specificity 15.2%), while the presence of Velcro crackles identified 16/39 patients with ground-glass opacities (sensitivity 41% and specificity 81.3%). Conclusions: The abnormal breath sounds in COVID-19 pneumonia had some consistent distributive characteristics and to some extent correlated with the radiologic features. Such evidence suggests that electronic auscultation is useful to aid diagnosis and timely management of the disease. Further studies are indicated to validate the accuracy and potential clinical benefit of auscultation in detecting pulmonary abnormalities in COVID-19 infection.

Evolution of Non-metallic Inclusions Through Processing in Ti-V Microalloyed 316L and Al-V Microalloyed 17-4PH Stainless Steels for Hipping Applications

Powders produced by air-melted gas atomization (AMGA) and vacuum induction gas atomization (VIGA) from Ti-V microalloyed 316L and Al-V microalloyed 17-4PH stainless steels along with their feedstock material and Hot Isostatically Pressed (HIP’d) products have been examined. Inclusion characteristics and development through process along with changes in grain size have been characterized. The main findings are that a thin oxide film forms on the powder surface, thicker for the 316L powder than the 17-4PH powder as indicated by XPS analysis of selected powder precursors, and large inclusions (predominantly oxides) are also observed on the 316L powder. This results in a high number of inclusions, including more complex two-phase inclusions, on the prior particle boundaries in the HIP’d material. Grain growth occurs during HIPping of the 316L powders with some evidence of inclusions locally pinning boundaries. In the vacuum-melted powder, smaller Ti-rich inclusions are present which give more grain boundary pinning than in the air-melted powder where Ti was lost from the material during melting. Consideration has also been made to determine the variation of Ti and V microalloying elements and residual Cu through processing. It was found that Ti was lost during air melting but partly retained after vacuum melting leading to the presence of fine and complex Ti-containing precipitates which provided grain boundary pinning during HIPping and heat treatment. V was retained in the melt by the use of both AMGA and VIGA processes, and therefore available for precipitation during HIPping. Residual Cu was retained during both air and vacuum melting and was associated with Mn S and Mn O S inclusions overwhelmingly outweighing that of Mn O inclusions in the two HIP’d 316L samples.

Evaluation of grain size and content of nonplastic fines on undrained behavior of sandy soils

Marine sandy soils may liquefy under wave loading and/or seismic loading. Current research shows that the presence of fines can significantly affect the liquefaction potential of sandy soils. Thus, a quantitative evaluation of the effect of fines on the undrained behavior of sandy soils can provide useful information on soil liquefaction that can advance the design of foundations of coastal structures. However, little is known about how the grain size of nonplastic fines affects the mechanical behavior of sandy soils. In this study, a series of strain-controlled monotonic undrained triaxial compression tests and critical-state constitutive modeling are carried out on a medium dense saturated sandy soil for various fines contents (FCs), mean grain sizes ( s) of nonplastic fines, and initial effective confining pressures. The results show that the peak deviatoric stress decreases significantly with decreasing especially for high FCs. The equivalent granular state parameter (ψ*) at the phase transformation can be used to characterize the effect of fines on the dilatancy of sandy soils in constitutive modeling. Additionally, the initial value of ψ*() serves as physical index for characterizing the influence of fines on the undrained instability state of sandy soils.