Search results

The purpose of this paper is to detail experiences that sickle cell disease (SCD) patients associate with healthcare justice and injustice in pain control.

A content analysis study of open-ended comments written by 31 participants who completed a 20-item healthcare injustice questionnaire-revised twice: once in reference to experiences with doctors and once in reference to experiences with nurses.

Participants’ mean age was 33±10 years; most were African-Americans and women. Themes showed: the four domains of healthcare justice were represented in patients’ comments; examples of justice and injustice were provided; specific incidents and interactions with healthcare providers were memorable to patients; and setting was a factor important to healthcare experiences because expectations about services vary by setting.

Patients were self-selected. Future work will include qualitative interviews and focus groups to uncover more details about how patients experience healthcare injustice.

Additional training is needed for SCD providers and about proper management of sickle cell pain; educational modules are also needed that address areas of healthcare injustice by patients.

The authors are the first to report how patients define healthcare justice and injustice. Specific details about memorable SCD patient-provider interactions and pain control are described.

The purpose of this paper is to investigate the magnetohydrodynamics mixed convection flow over an exponentially stretching surface in the presence of non-uniform heat source/sink and cross-diffusion. Adequate non-similar transformations are used to transform governing mixed convection boundary layer equations to dimensionless form.

These dimensionless partial differential equations are solved by using implicit finite difference scheme in conjunction with Quasi-linearization technique.

The effects of admissible parameters such as Eckert number (Ec), the ratio of buoyancy forces parameter (N), non-uniform heat source/sink, Soret and Dufour numbers on flow, temperature and concentration distributions are discussed and analysed through graphs. In addition, the results for skin friction coefficient, Sherwood number and Nusselt number are presented and discussed graphically.

In literature, no research work has been found in similar to this research paper.

It is essentially valuable to use simpler methods for making the protected pigment by inclusion of hematite in a transparent zirconium silicate crystal. The purpose of this paper is to compare solution combustion and co‐precipitation methods as two different routes for synthesis of zircon‐based coral pigment.

X‐ray diffraction, scanning electron microscopy and simultaneous thermal analysis were used to characterise and evaluate the precipitated zircon and Fe₂O₃ phases. The synthesised samples were incorporated into a suitable ceramic glaze and then their L*, a* and b* colour parameters were measured via Commission Internationale de I'Eclairage colorimetric method.

The results revealed that partial reduction of hematite (α‐Fe₂O₃) to maghemite (γ‐Fe₂O₃) destroyed the quality of the pigment obtained from the combustion processing method. Nevertheless, it is found that co‐precipitation would be an appropriate method for synthesis coral pigment.

It is found that the solution combustion method is not able to directly synthesise a zircon‐based coral pigment during combustion reaction. Furthermore, the presence of carbon has led to partial reduction of hematite resulting in unwanted crystalline maghemite phase. This reveals that solution combustion method is not suitable to obtain zircon‐based coral pigment.

The conventional method to synthesise ceramic pigments is a solid‐state reaction that requires high temperature and long processing time. The products are usually coarse and inhomogeneous so this method requires further processing like wet or dry milling in order to produce fine powders. Diffusion barrier in solid‐state processing prevents the control of the microstructure and the reactivity of the system. Soft‐chemical routes such as solution combustion and co‐precipitation methods are better choices to get finer powders and to achieve the desired phases at lower temperatures in shorter time as well.

Co‐precipitation synthesis of iron‐zircon coral pigment using sodium silicate (water glass) as Si source and its comparison with solution combustion method is valuable and has not been reported until now.

Financial technology (FinTech) is undergoing a transformation as a result of robotics and artificial intelligence. FinTech service providers are embracing contactless technology, including the development and widespread adoption of innovative payment service. Among the many types of contactless payment services, facial recognition payment (FRP) has gained in popularity. To capitalize on this rising popularity, comprehending the mechanisms underlying continuous usage intention toward FRP is essential. Drawing from the stimulus–organism–response (S-O-R) model, this study investigates how FRP attributes facilitate continuous usage intention.

In total, 321 Chinese FRP users completed an online survey. Partial least squares structural equation modeling analyzed the results of the survey.

The results reveal that relative advantage and compatibility, user-interface attractiveness and perceived security (stimuli) promote performance expectancy, effort expectancy and positive emotion (organism), which in turn foster FRP continuous usage intention (response).

This research presents an S-O-R model that incorporates several attributes from DOI theory, the UTAUT model and the AIDUA framework to elucidate the antecedents of consumers' continuous usage intention toward FRP. The findings corroborate the significance of the S-O-R mechanism in FRP, setting the groundwork for the acceptance and development of biometric authentication technologies in service contacts and banks. In addition, the study highlights opportunities and essential aspects for FinTech service developers and providers to consider in terms of their practical significance.

This study aims to obtain the mechanistic insights for the fabrication of pure copper thin wall components by selective infrared (IR) laser melting (SLM) and correlated with microstructure development, microhardness, surface morphology and phase analysis. Experimental processes for single track and selection of substrate materials have been studied using a combination of different laser powers and scanning speeds.

SLM of pure copper was performed on a YONGNIAN Laser YLMS-120 SLM machine using an Nd: YAG fiber laser operating at 1,060 nm in the NIR region. Single-track experiments and processing parameters are investigated through different combinations of laser power and scanning speed. The microstructure of the fabricated pure copper samples by SLM technique was analyzed by means of X-ray diffraction, scanning electron microscope equipped with energy disperse spectrometer, optical microscope (OM) and micro-hardness tester.

Steel-based substrates were found suitable for pure copper manufacturing due to sufficient heat accumulation. The width of a single track was determined by liner energy density, showing discontinuities and irregular morphologies at low laser powers and high scanning speeds. As a result of instability of the molten pool induced by Marangoni convection, cracks and cavities were observed to appear along grain boundaries in the microstructure. The top surface morphology of SLM-processed component showed a streamflow structure and irregular shapes. However, the powder particles attached to side surface, which manifest copper powders, are even more sensitive to melt pool of contour track. The crystal phase characteristics of copper components indicated increasing crystallite size of a-Cu, and the decreasing intensity of diffraction peak was attributed to the presence of defects during SLM. The maximum relative density and microhardness were 82 per cent and 61.48 HV0.2, respectively. The minimum thickness of a pure copper thin wall component was 0.2 mm.

This paper demonstrated the forming mechanism and explored feasibility of pure copper thin wall parts by SLM technology in the NIR region. The surface morphology, microstructure and crystal structure were preliminary studied with laser processing parameters.

This study aims to synthesize two different benzoxazines (Bz) monomers using bio-based and petroleum-based primary amines, respectively, and they have been compared to study their thermal and mechanical performances.

A bio-based bisphenol, Divanillin (DiVa), was formed by reacting two moles of vanillin with one mole of ethylenediamine (EDA) which was then reacted firstly with paraformaldehyde and EDA to form the benzoxazine DiVa-EDA-Bz, and secondly with paraformaldehyde and furfuryl amine (FFA) to form the benzoxazine DiVa-FFA-Bz. The molecular structure and thermal properties of the benzoxazines were characterized by fourier transform infrared spectroscopy and nuclear magnetic resonance (1H,13C) spectroscopies, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. The benzoxazines were further coated on mild steel panels to evaluate their mechanical properties and chemical resistance.

The DSC results of DiVa-FFA-Bz showed two exothermic peaks related to crosslinking compared to the one in DiVa-EDA-Bz. The DiVa-FFA-Bz also showed a higher heat of polymerization than DiVa-EDA-Bz. The TGA results showed that DiVa-FFA-Bz exhibited higher thermal stability with a residual char of 54.10% than 43.24% for DiVa-EDA-Bz. The chemical resistance test results showed that DiVa-FFA-Bz showed better chemical resistance and mechanical properties due to its higher crosslinking density.

This study shows the use of bio-based materials, vanillin and FFA, for synthesizing a benzoxazine resin and its application at high temperatures.

Low nickel austenitic stainless steel (ASS) has attracted much attention worldwide because of its economical price. This study aims to investigate the effect of different corrosive environments on the corrosion behavior of chrome-manganese (Cr-Mn) ASS. The tests were carried out as a function of H₂SO₄ concentrations, temperature and addition of ammonium thiocyanate (NH₄SCN) (0.01 M). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were used to study the corrosion behavior of Cr-Mn ASS. It was observed that with increasing H₂SO₄ concentration, temperature and with the addition of NH₄SCN solution, icorr, icrit and ipassive values increased. EIS data show decreasing charge transfer resistance value with increasing concentration and temperature. Higher corrosion rate with increasing temperature and concentration of H₂SO₄ is related to the anions (SO₄²⁻), which is responsible for reducing the stability of passive films. With the presence of 0.01 M NH₄SCN thiocyanate (SCN⁻ anion), there is a higher dilution of the passive film resulting in a higher corrosion rate. Energy-dispersive spectroscopy (EDS) analysis reveals the adsorption of sulfur on the surface in NH₄SCN containing a solution. The significant presence of counter ions and the adsorbed sulfur species on the steel surface play a vital role in corrosion behavior.

All the experiments were performed on a 3 mm thick sheet of Cr-Mn ASS (202 ASS) in hot rolled condition. The samples were then annealed at 1,050°C for 1 h, followed by water quenching. For microstructural examination, they were electrochemically etched in 10 Wt.% oxalic acid solution at 1 amp for 90 s. A computer-controlled Potentiostat (Biologic VMP-300) was used. After the cell was set up, the working electrode (WE) was electrostatically cleaned at −1 V vs saturated calomel electrode (SCE) for 30 s to remove the air-formed film. Then, WE were allowed to attain stable open circuit potential (OCP) for 1 h, following by the EIS test and potentiodynamic polarization test. The polarization test was started from a cathodic potential (−1.2 V vs SCE) and continued up to an anodic potential (1.6 V vs SCE) a scan rate of 0.1667 mV/s. EIS experiment was conducted on the same instrument by using a sinusoidal AC signal of 10 mV in a frequency range of 1,000,000 to 0.01 Hz at OCP.

Potentiodynamic polarization graph shows that with the increase in sulphuric acid concentration. Increasing temperature from 20°C to 80°C in 0.5 M H₂SO₄ solution increases the corrosion rate (icorr) of Cr-Mn ASS. On the addition of 0.01 M NH₄SCN to the sulfuric acid solution (0.1, 0.5 and 1 M) the corrosion rate increases drastically almost four to five times. EDS and XRD analysis shows the presence of sulfur over the oxide film and preferential site for dissolution of Cr and Mn at the steel surface when NH₄SCN is added to the sulfuric acid solution.

A study on the corrosion behavior of Cr-Mn ASS is scanty according to the author’s knowledge. Therefore, the present study will investigate the corrosion behavior of Cr-Mn ASS on SO₄⁻² anions, temperature and the addition of SCN⁻ ion in sulfuric acid.

This review aims to give an overview about zinc oxide (ZnO) based gas sensors and the role of doping in enhancing the gas sensing properties. Gas sensors based on ZnO thin film are preferred for sensing applications because of their modifiable surface morphology, very large surface-to-volume ratio and superior stability due to better crystallinity. The gas detection mechanism involves surface reaction, in which the adsorption of gas molecules on the ZnO thin film affects its conductivity and reduces its electrical properties. One way to enhance the gas sensing properties is by doping ZnO with other elements. A few of the common and previously used dopants include tin (Sn), nickel (Ni) and gallium (Ga).

In this brief review, previous works on doped-ZnO formaldehyde sensing devices are presented and discussed.

Most devices provided good sensing performance with low detection limits. The reported operating temperatures were within the range of 200̊C –400̊C. The performance of the gas sensors can be improved by modifying their nanostructures and/or adding dopants.

As of yet, a specific review on formaldehyde gas sensors based on ZnO metal semiconductors has not been done.

The purpose of this study is to investigate the effects of film holes’ arrangements and jet Reynolds number on flow structure and heat transfer characteristics of jet impingement conjugated with film cooling in a semicylinder double wall channel.

Numerical simulations are used in this research. Streamlines on different sections, skin-friction lines, velocity, wall shear stress and turbulent kinetic energy contours near the concave target wall and vortices in the double channel are presented. Local Nusselt number contours and surface averaged Nusselt numbers are also obtained. Topology analysis is applied to further understand the fluid flow and is used in analyzing the heat transfer characteristics.

It is found that the arrangement of side films positioned far from the center jets helps to enhance the flow disturbance and heat transfer behind the film holes. The heat transfer uniformity for the case of 55° films arrangement angle is most improved and the thermal performance is the highest in this study.

The film holes’ arrangements effects on fluid flow and heat transfer in an impingement cooled concave channel are conducted. The flow structures in the channel and flow characteristics near target by topology pictures are first obtained for the confined film cooled impingement cases. The heat transfer distributions are analyzed with the flow characteristics. The highest heat transfer uniformity and thermal performance situation is obtained in present work.

The purpose of this paper is to study properties of magnesium oxide and mixed magnesium oxide‐bismuth oxide thick films for application in tuned devices.

The effect of magnesium oxide and mixed magnesium oxide‐bismuth oxide thick films overlay of different thickness on Ag thick film microstrip rectangular patch antenna was investigated in the X band (8‐12 GHz). Using Ag thick film microstrip rectangular patch antenna the thick and mixed thick films was characterized by microwave properties such as resonance frequency, amplitude, bandwidth, quality factor and input impedance. Using the resonance frequency the permittivity of magnesium oxide and mixed magnesium oxide‐bismuth oxide thick films was measured.

Cubic structure of single magnesium oxide and monoclinic structure of bismuth oxide was present in mixed thick film. Also the morphology of single thick films was maintained in mixed thick film of magnesium oxide‐bismuth oxide. Due to overlay magnesium oxide and magnesium oxide‐bismuth oxide mixed thick films, change in resonance frequency shifts towards high frequency end was observed. Dielectric constant of magnesium oxide and mixed magnesium oxide‐bismuth oxide thick film calculated from resonance frequency decreased with increase in thickness.

The microwave properties using Ag thick film microstrip patch antenna due to overlay of magnesium oxide and mixed magnesium oxide‐bismuth oxide thick films have been reported for the first time. Thickness of overlay dependent tuning of the antenna has been achieved.