Variations of physical properties of seawater (sound speed, temperature, salinity, and density) over the southern shelf of the Caspian Sea were assessed. Furthermore, the effect of monthly changes in ...physical structure and layering procedure was evaluated on water characteristics. The influence of the thermal structure and stability of the water column in warm months on the sound speed was greater than that of the salinity parameter. Due to the high correlation between sound speed and temperature in the Caspian Sea water, their vertical structures are mostly correlated. The range of surface layer water changes was within 9–30°C during different months of the year. The water salinity in the areas away from the coast was measured around 12 to 12.5 PSU. The range of measured sound speed data in February was about 1450–1463 m/s, while the values recorded in June‑July were between 1501–1451 m/s. The results indicated formation of a deep acoustic channel in the middle and deep areas of the seawater column. The analysis revealed that the axis of the sound channel occurs at a depth of 140–150 m (intermediate layer) in warm months. The axis of the sound channel was located in upper layers in the warm months
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Advanced oxidation process is a rapidly expanding technology for wastewater treatment. In the current case study, the design of experiments (DOE) which is based on response surface methodology (RSM), ...was employed for the investigation of the effective parameters of malachite green (MG) degradation from aqueous medium. Three independent factors involving concentration of dye, the amount of the chemical oxidant and amount of iridium (Ir) as a doping agent on the MG degradation were examined in detail. Based on the results obtained from RSM analyses, an optimum pathway to reach the high MG degradation rate (>90%) under visible light was achieved by applying 10 ppm of MG concentration, 0.3224 mmol of chemical oxidant with 5% Ir doped ZnO. The experimental results proved to be in reasonable agreement with the derived response model with R2 > 0.98. The synthesized photocatalyst was in detail characterized. The photocatalytic degradation of MG at different conditions was found to be fit with the second-order kinetic equation, as the best choice for efficiency, which describes the behavior of dyes adsorption.
•Ir doped ZnO photocatalysts were successfully fabricated by sonochemical technique.•The photocatalytic activity of Ir doped ZnO was studied under visible irradiation.•The optimal condition of process was estimated via response surface methodology.•The second-order kinetic equation was selected for degradation of malachite green.
This paper studies the propagation of free, long waves on a potential vorticity front in the presence of a vertical coast, using a
$1{\textstyle \frac{1}{2}}$
-layer, quasi-geostrophic model with ...piecewise-constant potential vorticity. The coastal boundary induces flow through image vorticity and a Kelvin wave, either of which can reinforce or oppose the Rossby wave dynamics at the front. The behaviour of the front depends strongly on the relative strengths of these three mechanisms, which are explicit in our model. The richest behaviour, which includes kink solitons (under-compressive shocks) and compound-wave structures, occurs in the regime where vortical effects are dominant. The evolution of the front is described by a fully nonlinear finite-amplitude equation including first-order dispersive effects, which is related to the modified Korteweg–de Vries equation. The different behaviours are classified using the canonical example of the Riemann problem, which we analyse using El’s technique of ‘dispersive shock-fitting’. Contour-dynamic simulations show that the dispersive long-wave theory captures the behaviour of the full quasi-geostrophic system to a high degree of accuracy.
•New extended finite volume method for dynamic crack propagation.•New enriched hp-cloud shape functions with Kronecker delta property.•Appropriate modeling of displacement discontinues in the cracked ...media.•Meshless based tracking of the crack path.•Predicting the crack path in good agreement with the experimental results.
In the present work, an extended finite volume method (EFVM) is incorporated with the enriched hp-cloud approximate function which has Kronecker delta property (EHPCK) for modeling crack propagation in 2D media. In this approximation function, appropriate crack path enrichment and crack tip enrichment functions are considered for modeling the discontinuous displacement field of cracked bodies. Unlike the conventional FVM approach, in the proposed EFVM, excessive control volumes (CVs) are embedded inside the main CVs which are called here as enrichment control volumes (ECVs). The EFVM method doesn't restrict the crack propagation path to obey any predefined path or edges of control volumes. To increase the prediction accuracies, the subtriangular technique is applied for the integration on the cracked control volumes. Capability of introduced EFVM is investigated by solving different problems such as dynamic stress intensity factor calculations and dynamic crack propagation.
The long-wave, reduced-gravity, shallow-water equations (the semi-geostrophic equations) are used to study the outflow of a river into the ocean. While previous models have studied dynamics driven by ...gradients in density, the focus here is on the effects of potential vorticity anomaly (PVa). The river water is taken to have the same density as a finite-depth upper layer of oceanic fluid, but the two fluids have different, uniform, potential vorticities. Under these assumptions, the governing equations reduce to two first-order, nonlinear partial differential equations which are integrated numerically for a prescribed efflux of river water and PVa. Results are found to depend strongly on the sign of the PVa, with all fluid turning downstream (in the direction of Kelvin-wave propagation) when the river water has positive PVa and anticyclonic flow upstream of the river mouth when the PVa is negative. In all cases, a nonlinear Kelvin wave propagates at finite speed ahead of the river water. Away from the river mouth, the uniformity of one set of Riemann invariants allows for similarity solutions that describe the shape of the outflow, as well as a theory that predicts properties of the Kelvin wave. A range of behaviours is observed, including flows that develop shocks and flows that continue to expand offshore. The qualitative behaviour of the outflow is strongly correlated with the value of a single dimensionless parameter that expresses the ratio of the speed of the flow driven by the Kelvin wave to that driven by image vorticity.
•Novel PSf/HAO nanocomposite was prepared for effective oil/water emulsion separation.•The nanocomposite preparation process is simple, low-cost and applicable.•The optimized nanocomposite has ...super-hydrophilic characteristic (contact angle=8°).•Permeate flux was increased from 150.8 for PSf to1194L/m2hbar for PSf/HAO-2.•PSf/HAO-2 exhibited excellent oil rejection using the 1g/L oil–water emulsion as feed.
In this work, flat sheet polysulfone (PSf)-based membranes modified with inorganic hydrous aluminum oxide (HAO) nanoparticles were used as antifouling ultrafiltration membranes for removing oil molecules from oily solution. SEM, AFM and FTIR analyses were performed on the fabricated membranes to study the effect of HAO nanoparticles loading on the membrane properties. The membrane hydrophilicity and separation performance were determined through contact angle measurement and cross-flow ultrafiltration of oily solution, respectively. Results showed that the hydrophilicity of HAO-modified membrane was increased remarkably upon addition of the highest weight ratio of HAO nanoparticles to PSf (i.e. 2:1), which led to a significant rise in permeate flux, achieving 1194L/m2hbar in comparison to 151L/m2hbar shown by the plain PSf membrane. With respect to oil removal efficiency, the modified membrane was found to exhibit almost complete elimination of oil molecules with flux recovery ratio of around 67% after a simple water washing process. The promising results achieved by the modified PSf membrane could be mainly due to the presence of hydroxyl functional groups on the membrane surface upon addition of highly hydrophilic HAO nanoparticles, which improved not only membrane water permeability but also its antifouling ability.
This paper studies the hydraulic control of continental shelf waves using an inviscid barotropic quasi-geostrophic model with piecewise-constant potential vorticity, in which the shelf is represented ...by a flat step of variable width. A coastal-intensified geostrophic current generates topographic Rossby waves, which can become critical at a local decrease in shelf width when the background current opposes Rossby wave propagation. That is, the shelfbreak perturbation permanently modifies the flow field over arbitrarily large distances and the flow transitions from subcritical to supercritical as it crosses the perturbation. Critically controlled flows also lead to the exchange of significant volumes of water between the shelf and the deep ocean. We derive the boundaries for which critical control occurs in terms of a Froude number and the dimensionless magnitude of the perturbation, and analyse the possible transitions between controlled and far-field flow. When first-order dispersive terms are included in the model, transitions are resolved by dispersive shock waves, which remain attached to the forcing region when the Froude number is close to the boundary for critical flow. Contour dynamic simulations show that the dispersive long-wave model captures the quantitative behaviour of the full quasi-geostrophic system for slowly varying shelves, and replicates the qualitative behaviour even when the long-wave parameter is order one.
Work-related hand injuries are the primary cause of disability and prolonged time away from work. This prospective cohort study was conducted to determine the predictors of return to work (RTW) after ...traumatic work-related hand injuries. Our study included 280 patients who were referred to the Plastic and Reconstructive Center for treatment of their occupational hand injuries from July 2017 to February 2018. Several functional questionnaires were completed, and they were followed up at 1, 3 and 8 weeks. Telephone interviews were done 3 months later. Approximately half the subjects had returned to work during the first 3 months after a median time away of 57 days. No relationship was found between age, gender, marital status, hand dominance and RTW time. Nevertheless, there was correlation between RTW time with cigarette smoking, injury severity and disability. Our study findings suggest that injury severity and higher work disability scores are prognostic factors for RTW. Also, smoking was associated with later RTW, which could be the result of poor circulation and delayed healing. Employers should implement injury prevention programs with appropriate rehabilitation that takes into consideration the severity of the hand injury, and health strategies to improve unhealthy lifestyle factors such as smoking.
Les traumatismes de la main au travail sont la principale cause d’invalidité et de longue durée de congé chez les travailleurs à un âge productif. Cette étude de cohorte prospective a été menée pour déterminer les facteurs prédictifs de retour au travail (RAT) après des blessures traumatiques des mains survenues au travail. Notre étude a porté sur 280 patients qui furent envoyées au Service de chirurgie plastique et reconstructrice pour le traitement de leurs blessures professionnelles aux mains de juillet 2017 à février 2018. Plusieurs questionnaires ont été remplis et les blessés ont été suivis à 1, 3 et 8 semaines. Un entretien téléphonique a été effectué 3 mois plus tard. Environ la moitié des sujets étaient retournés au travail dans les 3 premiers mois avec le délai médian de 57 jours. Aucune relation n’avait détecté entre l’âge, le sexe, l’état marital, la dominance de la main et le moment du RAT. Néanmoins, il y avait une corrélation entre le moment du RAT et le tabagisme, la sévérité des blessures et le degré d’invalidité. Les résultats de notre étude suggèrent que la sévérité des blessures et un score plus élevé d’incapacité de travail étaient des facteurs pronostiques pour RAT. Le tabagisme a également été associé à un RAT différé, qui pourrait être le résultat d’altérations dans la circulation sanguine et d’un retard dans la cicatrisation. Il est recommandé que les employeurs mettent en œuvre des programmes de prévention de la sécurité et des programmes de réadaptation adéquats qui tiennent compte de la gravité des blessures à la main, et de stratégies de santé pour améliorer les modes de vie malsains comme le tabagisme.
Objectives
Periodontal and cardiovascular diseases share some common underlying mechanisms. Hyperlipidemia is a major risk factor for cardiovascular diseases. This study sought to assess the ...association of hyperlipidemia and statin consumption with periodontal status.
Materials and Methods
This cross‐sectional study was conducted on 150 participants including 50 individuals with normal lipid profile (group C), 50 hyperlipidemic patients without drug therapy (group N), and 50 hyperlipidemic patients on drug therapy for a minimum of 3 months (group S). Periodontal parameters including plaque index (PI), clinical attachment level (CAL), bleeding on probing (BOP), and pocket depth (PD) were measured for all teeth except for the third molars. Serum levels of total cholesterol (TC), HDL, LDL, and triglycerides (TGs) were measured.
Results
The mean values of CAL and PD were significantly higher in the two hyperlipidemic groups compared with the C group (P < 0.005). Also, CAL and PD had significant associations with serum levels of TGs, LDL, and TC (P < 0.0001); PI in the group S was significantly lower than that in the other groups (P < 0.005).
Conclusions
Hyperlipidemic patients showed higher values of periodontal parameters compared with the statin‐treated and control groups. Lower PI in the group S may indicate the anti‐inflammatory effect of statin.
Objectives
Food insecurity has gained attention as a potential risk factor for vision impairment. However, research on this topic is limited. This objective of this study was to investigate the ...relationship between food insecurity and visual impairment among adults aged 50 years or older using data from six low-and middle-income countries (LMIC).
Design and Setting
Data from the longitudinal Study on global AGEing and adult health (SAGE) were analyzed in a community-based, cross-sectional, and nationally representative sample.
Participants
Adults aged 50 years or older from six low- and middle-income countries (LMICs) including China, India, Mexico, Russia, South Africa, and Ghana.
Measurements
Food insecurity was evaluated using a questionnaire comprised of two questions that addressed the frequency of eating inadequately and hunger due to a lack of food in last 12 months. Distance and/or near vision impairment was considered as a visual acuity score of less than 6/18 in the eye with better vision.
Results
The analytical sample consisted of 29,804 adults (mean (SD) for age: 63.2 (9.54) years; 54.3% female). The prevalence of food insecurity, near vision and distance vision impairment in the sample was 16.4%, 36.7%, and 13.9%, respectively. Adjusted pooled analyses across countries revealed a significant association between food insecurity and distance (OR: 1.16; 95% CI: 1.01, 1.33; P=0.04, significant individually in India and South Africa) and near (OR: 1.12; 95% CI: 1.02, 1.22; P=0.01, significant individually in South Africa) vision impairment, and a between-country heterogeneity of 46.30% and 25.99%, respectively.
Conclusion
Food insecurity was associated with both distance and near vision impairment in adults aged 50 years or older across six LMIC. Food policies and intervention programs targeted at decreasing food insecurity in vulnerable households are essential.
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