Effects of roughness on droplet apparent contact angles on a fiber

This paper reports on our investigation of the effects of surface roughness on the equilibrium shape and apparent contact angles of a droplet deposited on a fiber. In particular, the shape of a droplet on a roughened fiber is studied via the energy minimization method implemented in the surface evolver finite element code. Sinusoidal roughness varying in both the longitudinal and radial directions is considered in the simulations to study the effects of surface roughness on the most stable shape of a droplet on a fiber (corresponding a global minimum energy state). It is found that surface roughness delays droplet shape transition from a symmetric barrel to a clamshell or an asymmetric barrel profile. A phase diagram that includes the effects of fiber roughness on droplet configurations-symmetric barrel, clamshell, and asymmetric barrel-is presented for the first time. It is also found that droplet apparent contact angle tends to decrease on rough fibers. Likewise, roughness tends to increase the force required to detach a droplet from a fiber but the effect diminishes as droplet size increases relative to the size of surface roughness. The results presented in our study have been compared with experimental data or those from prior studies whenever possible, and good agreement has been observed

On applications and limitations of one-dimensional capillarity formulations for media with heterogeneous wettability

Force-balance-based one-dimensional algebraic formulations that are often used in characterizing the capillarity of a multi-component system (e.g., predicting capillary height rise inporous media) are discussed. It is shown that such formulations fail to provide accurate predictions when the distribution of wetting (or non-wetting) surfaces is not homogeneous. A more general mathematical formulation is suggested and used to demonstrate that for media with heterogeneous wettability, hydrophilic (or hydrophobic) surfaces clustered in groups will have less contribution to the overall capillarity of the system

A survey on surfactant concentration in southern Caspian Sea

We determined concentration of surfactants as mg/I of LAS using Sublation-Methylen Blue method in the south Caspian Sea coastal areas extending from Astara to Bandar-e-Tourkaman. The method was based on the American Standard Method for Examination of Water and Wastewater. We analyzed 53 water samples and found an average surfactant concentration of 0.019mgi1 with the minimum and maximum being 0.008mg/I and 0.038mgi1 respectively. We conclude that presently, surfactant concentration is not critical in the coastal areas. However, care must be exercised interpreting these results considering the synergistic effects between the surfactants and heavy metals and oil hydrocarbons

Physical and chemical factors determination of Mohammadiye Channel water for aquaculture purposes

In this survey the Physical and Chemical factors were studied in mohammadiye channel extending Eslamshahr, Robat karim and Shahriar cities of Tehran Province during the 2011 in agriculture period (May, June, July, August, September, October) Sampling were done from 5 different stations. The measured factors were temperature,DO, Cl,HCO3,COD,BOD,CO2,Mg,… The analysis of Physical and Chemical factors of Mohammadiye channel water showed that except water temperature, all factors in comparison to the standards were at the standard level, So they are suitable for aquaculture. Due to mean of water temperature that is high from middle of Spring to the end of summer, It is suitable for culture of warmwater fishes and because of low water temperature in the station No1 It is recommended for culture of coldwater fishes by using of 50-70gr of young fishes

Retinoic acid effects on nuclear maturation of bovine oocytes in vitro

In the present study, the effect of all-trans retinoic acid (t-RA) administration during in vitro maturation (IVM) on bovine oocytes maturation was determined. Concentrations of t-RA (RA; 0, 0.25, 0.5 and 1 μM) and 0.1% ethanol (vehicle) were included in the maturation medium. Ovaries collected from the local abattoir were transported to the laboratory in in 0.9% NaCl with 100 IU/ml penicillin and 100 in vitro maturation (IVM) on bovine oocytes maturation was determined. Concentrations of t-RA (RA; 0, 0.25, 0.5 and 1 μM) and 0.1% ethanol (vehicle) were included in the maturation medium. Ovaries collected from the local abattoir were transported to the laboratory in in 0.9% NaCl with 100 IU/ml penicillin and 100  in vitro maturation (IVM) on bovine oocytes maturation was determined. Concentrations of t-RA (RA; 0, 0.25, 0.5 and 1 μM) and 0.1% ethanol (vehicle) were included in the maturation medium. Ovaries collected from the local abattoir were transported to the laboratory in in 0.9% NaCl with 100 IU/ml penicillin and 100 g/ml streptomycin at 30 - 35°C within 1-2 h after collection. The oocytes of antral follicles, 2 to 8 mm in diameter, were recovered by aspiration. After preliminary evaluation, the oocytes were selected and washed four times in HEPES-TCM 199 supplemented with 2% FBS, 0.2 mM sodium pyruvate, 100 IU/ml penicillin and 100 g/ml streptomycin. Then 10 cumulus-oocyte complexes (COCs) were subjected to each droplet of maturation medium and incubated at 38.5°C, 5% CO2 and 95% humidity for 24 h. Maturation medium was bicarbonate-buffered TCM199 supplemented with 10% FBS, 0.2 mM sodium pyruvate, 5 μg/ml bovine FSH, 0.01 IU/ml bovine LH, 100 IU/ml penicillin and 100 g/ml streptomycin. Results show different concentrations of t-RA have no effect on cumulus expansion. The rate of oocytes developing to the MII stage compared to control, vehicle, and 0.25 μM groups was significantly increased with 1 μM t-RA treatment (

The effect of mathematical skills training in teaching physics on promoting task value and minimizing educational burnout among high school grade twelve students

Background and Objectives: The educational Burnout and task value are among the most important variables in the field of education. Educational burnout refers to feeling of tiredness in doing tasks and study, as well as a pessimistic Attitude to education and curriculum and a feeling of inadequacy. The task value is one's perception of tasks and its importance, which includes the components of interest, importance, and usefulness. Research has shown that these two variables can affect academic outcomes. The purpose of this study was to investigate the effect of training math skills in physics education on improving the task values and reducing the educational Burnout of 12th grade students. In this regard, the present study aimed to compare students with and without training math skills in physics education in terms of the educational Burnout and task value. Materials and Methods: The present research method was a quasi-experimental design as a pre-test-post-test with a control group. In this study a sample of two classes with 36 students from the 12th grade math-physics students from the statistical community of students of the District 1 of Tabriz was selected in the first semester of the 2018-19 academic year. The students in this study were selected by Targeted Sampling and then randomly assigned to two experimental and control groups. Students in the experimental group were exposed to math skills training for 8 sessions and the control group received traditional training over the same period. The training math skills in physics education package has been prepared by physics teachers and reviewed and approved by professors in the field of education and physics at the university. This package included justifying students about training math skills and their applications in training physics concepts such as vector analysis in physics, linear function and its application in physics, Quadratic function and its application in physics ،Tangents and slope. Both groups were evaluated before and after the study by educational burnout and task value questionnaires. The obtained data were analyzed using covariance method. Findings: The results of study showed that there is a significant difference between the two groups in terms of their educational burnout. Students who had math skills training in physics education demonstrated lower educational burnout in compare with control group. The results also showed that there was a significant difference between the two groups in the task value. The results show that students who have been taught math skills show a higher task value. Conclusion: The results of the research confirm the effect of teaching math skills in physics education on improving the task values and reducing educational burnout of students.The results can be used in the field of education. In this regard, it is suggested that in order to improve the task value and reduce academic burnout and consequently to improve academic outcomes, the teaching math skills in physics education should be considered. The study did not examine burnout subscales.  In future researches, it is suggested that the effect of teaching math skills on physics education on the subscale of academic burnout be examined.   ===================================================================================== COPYRIGHTS  ©2020 The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers.  ====================================================================================

Effect of fiber orientation on shape and stability of air-water interface on submerged superhydrophobic electrospun thin coatings

To better understand the role of fiber orientation on the stability of superhydrophobicelectrospun coatings under hydrostaticpressures, an integro-differential equation is developed from the balance of forces across the air–water interface between the fibers. This equation is solved numerically for a series of superhydrophobicelectrospun coatings comprised of random and orthogonal fiber orientations to obtain the exact 3D shape of the air–water interface as a function of hydrostaticpressure. More important, this information is used to predict the pressure at which the coatings start to transition from the Cassie state to the Wenzel state, i.e., the so-called critical transition pressure. Our results indicate that coatings composed of orthogonal fibers can withstand higher elevated hydrostaticpressures than those made up of randomly orientated fibers. Our results also prove that thin superhydrophobic coatings can better resist the elevated pressures. The modeling methodology presented here can be used to design nanofibrous superhydrophobic coatings for underwater applications

Blood Mercury Level and Its Determinants among Dental Practitioners in Hamadan, Iran

Objective: Exposure to mercury can occur in occupational and environmental settings.During clinical work with dental amalgam, the dental personnel are exposed to both metallic mercury and mercury vapor. The aim of the present study was to investigate bloodmercury level (BML) and its determinants among dentists practicing in Hamadan city,Iran.Materials and Methods: This cross sectional study was done on all dental practitioners of Hamadan (n=43). Dentists were asked to complete a questionnaire, and then 5 ml bloodsamples were obtained from them. After preparation, mercury concentration of each sample was measured by cold vapor atomic absorption device. Pearson correlation test and regression models served for statistical analysis.Results: The mean blood concentration of mercury was 6.3 μg/l (SD=1.31 range 4.15-8.93). BML was positively associated with age, years in practice, working hours per day,number of amalgam restorations per day, number of amalgam removal per week, sea foodconsumption, working years in present office, using amalgam powder, using diamond bur for amalgam removal, dry sterilization of amalgam contaminated instruments, and deficient air ventilation.Conclusion: BML of dentists in Hamadan was higher than standards. Working hours and number of amalgam restorations per day were significantly correlated with blood mercury

Antibacterial and Antifungal Activities of Punica Granatum Peel Extracts Against Oral Pathogens

Objective: Punica granatum has been used for many years in folk medicine due to several purposes. The aim of the present study was to evaluate the effect of methanolic extract of Punica granatum peel (MEPGP) against Streptococcus mutans, Staphylococcus aureus,Streptococcus salivarius, Streptococcus sanguinis, Staphylococcus epidermidis, Actynomyces viscosus, Lactobacillus acidophilus and Candida albicans.Materials and Methods: In this in vitro study, the mentioned oral organisms were cultured in blood agar and mueller-hinton media and then paper disks containing MEPGP at concentrations of 4 mg/ml, 8 mg/ml and 12 mg/ml were inserted on medias. The antimicrobialactivity was evaluated by agar disk diffusion method. The effects of three different concentrations of MEPGP against microorganisms were compared using one-way ANOVA and Tukey tests.Results: All concentrations of MEPGP had antibacterial activity against S. aureus and S.epidermidis. Only at concentration of 8 mg/ml and 12 mg/ml MEPGP was effective against L. acidophilus, S. mutans and S. salivarius. Furthermore; no concentrations ofMEPGP inhibited A. viscosus and C. albicans.Conclusion: This study suggests that MEPGP might be used as an antibacterial agent in controlling oral infections