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The architecture of complex-shaped fibres affects the motion of the contact line and the evolution of its associated menisci when a fibre is immersed into a liquid. Understanding and ...predicting the motion of the contact line is critical in the design of complex-shaped fibres for many engineering applications as well as for surface science. While wetting on classic circular cylinders has been well studied, singularities during the wetting process of complex-shaped fibres are not yet well understood.
The dynamic wetting behaviour of axisymmetric sinus-shaped fibres immersed vertically in a liquid volume was investigated. Fibres were 3D-printed down to micrometre dimensions, and the Wilhelmy method was used in parallel with meniscus shape analysis. Moreover, a quasi-static theoretical model predicting the contact line movement and free energy of the system evolution on these fibres is also proposed.
The observation of liquid advancing and receding fronts highlighted a stick-slip motion of the meniscus depending on both the fibre surface curvature and its intrinsic wettability. The model predicts that the behaviour of the seemingly pinned and then jumping contact line, with associated changes in apparent contact angles, can be explained by the interplay between a constant local contact angle and the movement of the bulk liquid, leading to the storage of energy which is suddenly released when the contact line passes a given point of fibre curvature. Besides, acceleration/deceleration events that take place before and after the jumps are experimentally observed in good agreement with the model.
An experiment using surface tension was conducted to investigate the interactions of promethazine hydrochloride (PMT), with TX-165, at the interface in different ratios and solvents (water/50 mmol/kg ...NaCl, and 500 mmol/kg urea) at 298.15 K. A thorough FTIR study of the employed pure and mixed system was also conducted in the aqueous solution. PMT is a medication employed to manage and cure allergic conditions. Usually, NaCl media improved the surface properties of singular and mixed components over aqueous media, resulting in synergistic/attractive interactions among ingredients. TX-165's composition at mixed monolayer (
$ X_1^{\sigma } $
X
1
σ
), surface excess concentration (Γ
max
), pC
20
, activity coefficient, and so on were evaluated. The achieved activity coefficient values are attained below one in each case, indicating the attractive interactions amongst ingredients. A negative Gibbs energy of adsorption
$ (\Delta G_{{\rm ads}}^\textrm{o}) $
(
Δ
G
ads
o
)
was obtained all through, indicating spontaneity in the process. A negative excess free energy (
$ {\Delta }G_{{\rm ex}}^\sigma $
Δ
G
ex
σ
) was found at the mixed interface of PMT + TX-165, showing a higher surface stability of mixed monolayer than pure component monolayer. FTIR spectroscopy is used to study the spectrum of single and mixed amphiphiles to validate the interaction between PMT and TX-165. This study suggested that TX-165 surfactant might behave as an able antidepressant drug delivery agent.
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A new technique of utilizing the dynamic surface tension (ST) data for solubility determination was proposed, tested, and verified in this study. Dibutyl phthalate was chosen as the ...surface-active component and its solutions were prepared with 0, 1, and 5wt.% aqueous methanol (MeOH) solutions. The solutions for ST measurement were prepared by stirring the aqueous DBP mixtures in a heated water bath (45°C) for an extended duration of time. The data revealed that an increase in DBP concentration corresponded to a more rapid relaxation of dynamic ST and reached a lower equilibrium ST; similar to that observed amongst typical micelle forming surfactants (at C<cmc). Unlike surfactants, an increase in concentration beyond a certain value corresponded to near-identical relaxations of dynamic ST and the same equilibrium ST. For typical surfactants, although the equilibrium ST remained constant when concentration was increased at C>cmc, the dynamic ST relaxations became increasingly rapid. These inconsistencies in dynamic ST behavior pointed towards the absence of micelle formation amongst the DBP molecules. Based on the dynamic ST data, the solubility of DBP in water, 1wt.%, and 5wt.% MeOH(aq) were found to be ∼6.1, ∼4.4, and ∼4.7 (10−8mol/cm3), respectively.
Although many unsaturated soil experiments have successfully delivered positive outcomes, most studies just concisely illustrated sensor techniques, because their main objectives focused on bridging ...research gaps. Inexperienced research fellows might rarely follow up those techniques, so they could encounter very trivial and skill-demanding difficulties, undermining the quality of experimental outcomes. With a motivation to avoid those, this work introduces technical challenges in applying three sensor techniques: high precision tensiometer, spatial time-domain reflectometry (spatial TDR) and digital bench scales, which were utilized to measure three fundamental variables: soil suction, moisture content and accumulative outflow. The technical challenges are comprehensively elaborated from five aspects: the functional mechanism, assembling/manufacturing approaches, installation procedure, simultaneous data-logging configurations and post data/signal processing. The conclusions drawn in this work provide sufficient technical details of three sensors in terms of the aforementioned five aspects. This work aims to facilitate any new research fellows who carry out laboratory-scale soil column tests using the three sensors mentioned above. It is also expected that this work will salvage any experimenters having troubleshooting issues with those sensors and help researchers bypass those issues to focus more on their primary research interests.
Amphiphilic fluorocarbon substances are a trending topic of research due to their wide range of applications accompanied by an alarming environmental and health impact. In order to predict their fate ...in the environment, use them more economically, develop new water treatment methods, etc., a better understanding of their physicochemical behavior is required. Their hydrophobicity in water/oil systems is particularly sensitive to one key thermodynamic parameter: the free energy of transfer of a perfluoromethylene group from oil to water. However, for the –CF2– moiety, the transfer energy values reported in the literature vary by more than ±25%. Due to the exponential relationship between this energy and the adsorption constants or the partition coefficients, such an uncertainty can lead to orders of magnitude error in the predicted distribution of fluorinated species. We address this problem by presenting an experimental determination of the hydrophobic effect of a –CF2– moiety with a greater certainty than currently available. The transfer energy is determined by measuring the interfacial tension of water|hexane for aqueous solutions of short-chained fluorotelomer alcohols. The obtained results for the free energy of transfer of a –CF2– moiety from oil to water are 1.68±0.02×RT0, 1.75±0.02×RT0, and 1.88±0.02×RT0 at 288.15 K, 293.15 K, and 303.15 K, respectively.
•Tensiometer reading errors propagate to soil hydraulic parameters.•Digital tensiometer overestimates soil matric potential.•Larger errors in K(θ) are obtained by Bourdon gauge and digital ...tensiometer.•Alternative tensiometers cause errors in the estimation of van Genuchten equation parameters.
The tensiometer represents an excellent instrument for measuring in situ soil water status. However, measuring soil matric potential requires a tensiometer reading system sensitive enough to accurately record the matric potential. Hence, an instantaneous profile-type experiment was conducted in the field, to measure the soil matric potentials within a moisture range from saturation to field capacity. After that, matric potential, soil moisture, total potential gradient, flow density and hydraulic conductivity were calculated and van Genuchten equation parameters were estimated through inverse modeling. This study aimed to test the Bourdon pressure gauge and digital tensiometer compared with the mercury manometer to measure the soil matric potential and to examine the differences related to the estimations of soil water content and to the associated variables. In addition, the study also aimed to evaluate soil hydraulic parameters by inverse modeling, based on the matric potentials from each reading system. Bourdon pressure gauge replaces the Hg manometer in the measurement of soil water matric potential within the moisture range from saturation to field capacity; The use of digital tensiometer and Bourdon pressure gauge reduced hydraulic conductivity by four and three times and flow density by approximately three and two times, respectively, at 6 kPa tension and, therefore, are not recommended for the estimation of these hydraulic parameters; Regardless of reading system used in the tensiometer, inverse modeling estimates well van Genuchten equation parameters and, consequently, soil water matric potential.
Little is known about how stormwater exfiltrates from green infrastructure and few efforts have been undertaken to address this question. This study used tensiometers to monitor water exfiltration ...from an aggregate-filled storage gallery installed under permeable pavement. An 80-space parking lot was built at Seitz elementary school in Fort Riley, KS under an agreement between EPA and US Army during the summer of 2015. A network of twelve tensiometers and twelve monitoring wells was installed under and south of the storage gallery. Tensiometers were installed a various depths and distances to monitor soil moisture tension. The installation was used to monitor subsurface water flow patterns from the storage gallery under the permeable pavement site. The results of the study showed that soil moisture tension is larger at the shallower depths, decreasing with depth from the ground surface. Larger soil tension was associated with increased distance from the permeable pavement storage gallery. The results showed exfiltration from both the sidewalls and the bottom of the gallery while the changes in soil tension were larger for the tensiometer monitoring exfiltration from the side walls. Both the accumulated water depth inside the storage gallery and groundwater level rise were positively correlated with total rainfall depth. The calculated vertical flow rate was larger than the horizontal flow. The soil water tension change associated with storage gallery exfiltration was measured in a radius of <5 m from the storage gallery. Long-term peak groundwater level rise should be considered for design of the storage gallery depth to maintain the effective exfiltration. Understanding the exfiltration pathways aids with the placement and design the storage gallery. Additional research is necessary to understand how specific local parameters and vadose zone characteristics would affect the long-term exfiltration process.
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•Tensiometer approach used for monitoring performance of urban green infrastructure.•Exfiltration was evident from both the sidewalls and the bottom of the storage gallery.•Exfiltration potentially followed a downward parabolic shape.•Accumulated water inside the galley and total rainfall depth were positively correlated with the soil tension changes.•Tensiometers beyond 4.5 m far from the storage gallery have shown little change in tension after the rain events.
Purpose
To evaluate intercompartmental load intraoperatively with a sensor after conventional gap balancing with a tensiometer during total knee arthroplasty (TKA).
Methods
Fifty sensor-assisted TKA ...procedures were performed prospectively between August and September 2018 with a cruciate-retaining prosthesis. After applying a modified measured resection technique, conventional balancing between resected surfaces was achieved. The equal and rectangular flexion–extension gaps were confirmed using a tensiometer at 90° and 5°–7° (due to posterior tibial slope) of knee flexion. Then, the load distribution was evaluated intraoperatively with a sensor placed on trial implants in the positions of knee flexion (90° flexion) and extension (10° flexion).
Results
The proportion of coronal load imbalance (medial load − lateral load ≥ ± 15 lb) was 56% in extension and 32% in flexion (
p
= 0.023). The proportion of sagittal load imbalance (extension load − flexion load ≥ ± 15 lb) was 36% in the medial compartment and 4% in the lateral compartment (
p
< 0.001). An additional procedure for load balancing was performed in 74% of knees.
Conclusions
Coronal and sagittal load imbalances existed as determined by the sensor even after the achievement of appropriate conventional gap balance. The additional rebalancing procedure was performed for balanced loads in 74% of the knees after conventional balancing. The use of an intraoperative load sensor offers the advantage of direct evaluation of the load on TKA implants.
Level of evidence
IV.
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