scholarly journals Roughness and Fiber Fraction Dominated Wetting of Electrospun Fiber-Based Porous Meshes

Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 34 ◽  
Author(s):  
Piotr Szewczyk ◽  
Daniel Ura ◽  
Sara Metwally ◽  
Joanna Knapczyk-Korczak ◽  
Marcin Gajek ◽  
...  
Keyword(s):  
Contact Angle ◽  
Electrospun Fiber ◽  
Three Dimensional ◽  
Contact Angles ◽  
Electrospun Fibers ◽  
Surface Geometry ◽  
Wetting Contact Angle ◽  
Fiber Fraction ◽  
Significant Difference ◽  
Entrapped Air

Wettability of electrospun fibers is one of the key parameters in the biomedical and filtration industry. Within this comprehensive study of contact angles on three-dimensional (3D) meshes made of electrospun fibers and films, from seven types of polymers, we clearly indicated the importance of roughness analysis. Surface chemistry was analyzed with X-ray photoelectron microscopy (XPS) and it showed no significant difference between fibers and films, confirming that the hydrophobic properties of the surfaces can be enhanced by just roughness without any chemical treatment. The surface geometry was determining factor in wetting contact angle analysis on electrospun meshes. We noted that it was very important how the geometry of electrospun surfaces was validated. The commonly used fiber diameter was not necessarily a convincing parameter unless it was correlated with the surface roughness or fraction of fibers or pores. Importantly, this study provides the guidelines to verify the surface free energy decrease with the fiber fraction for the meshes, to validate the changes in wetting contact angles. Eventually, the analysis suggested that meshes could maintain the entrapped air between fibers, decreasing surface free energies for polymers, which increased the contact angle for liquids with surface tension above the critical Wenzel level to maintain the Cassie-Baxter regime for hydrophobic surfaces.

scholarly journals Fabrication of a Simultaneous Highly Transparent and Highly Hydrophobic Fibrous Films

2021 ◽  
Vol 11 (12) ◽  
pp. 5565
Author(s):  
Doo-Hyeb Youn ◽  
Kyu-Sung Lee ◽  
Sun-Kyu Jung ◽  
Mangu Kang
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Water Contact Angle ◽  
Electrospun Fiber ◽  
Contact Angles ◽  
Light Transmittance ◽  
Electrospun Fibers ◽  
Water Contact ◽  
Aligned Fibers ◽  
Highly Hydrophobic

This paper discusses the fabrication and characterization of electrospun nanofiber scaffolds made of polystyrene (PS). The scaffolds were characterized in terms of their basis material molecular weight, fiber diameter distribution, contact angles, contact angle hysteresis, and transmittance. We propose an aligned electrospun fiber scaffold using an alignment tool (alignment jig) for the fabrication of highly hydrophobic (θW > 125°) and highly transparent (T > 80.0%) films. We fabricated the alignment jig to align the electrospun fibers parallel to each other. The correlation between the water contact angles and surface roughness of the aligned electrospun fibers was investigated. We found that the water contact angle increased as the surface roughness was increased. Therefore, the hydrophobic properties of the aligned electrospun fibers were enhanced by increasing the surface roughness. With the change in the electrospinning mode to produce aligned fibers rather than randomly distributed fibers, the transmittance of the aligned electrospun fibers increased. The increase in the porous area, leading to better light transmittance in comparison to randomly distributed light scattering through the aligned electrospun fibers increased with the fibers. Through the above investigation of electrospinning parameters, we obtained the simultaneous transparent (>80%) and hydrophobic (θW > 140°) electrospun fiber scaffold. The aligned electrospun fibers of PS had a maximum transmittance of 91.8% at the electrospinning time of 10 s. The water contact angle (WCA) of the aligned electrospun fibers increased from 77° to 141° as the deposition time increased from 10 s to 40 s. The aligned fibers deposited at 40 s showed highly hydrophobic characteristics (θW > 140°).

Surface Topography Induced Ultrahydrophobic Behavior: Effect of Three-Phase Contact Line Topology

2006 ◽  
Author(s):  
Neeharika Anantharaju ◽  
Mahesh Panchagnula ◽  
Wayne Kimsey ◽  
Sudhakar Neti ◽  
Svetlana Tatic-Lucic
Keyword(s):  
Contact Angle ◽  
Contact Line ◽  
Anomalous Behavior ◽  
Contact Angles ◽  
Wet Etching ◽  
Surface Geometry ◽  
Wetting Behavior ◽  
Void Fractions ◽  
Three Phase ◽  
Receding Contact

The wettability of silicon surface hydrophobized using silanization reagents was studied. The advancing and receding contact angles were measured with the captive needle approach. In this approach, a drop under study was held on the hydrophobized surface with a fine needle immersed in it. The asymptotic advancing and receding angles were obtained by incrementally increasing the volume added and removed, respectively, until no change in angles was observed. The values were compared with the previously published results. Further, the wetting behavior of water droplets on periodically structured hydrophobic surfaces was investigated. The surfaces were prepared with the wet etching process and contain posts and holes of different sizes and void fractions. The surface geometry brought up a scope to study the Wenzel (filling of surface grooves) and Cassie (non filling of the surface grooves) theories and effects of surface geometry and roughness on the contact angle. Experimental data point to an anomalous behavior where the data does not obey either Wenzel or Cassie type phenomenology. This behavior is explained by an understanding of the contact line topography. The effect of contact line topography on the contact angle was thus parametrically studied. It was also inferred that, the contact angle increased with the increase in void fraction. The observations may serve as guidelines in designing surfaces with the desired wetting behavior.

Pitch bearing/raceway fretting: Influence of contact angle

2018 ◽  
Vol 233 (5) ◽  
pp. 1734-1749 ◽  
Author(s):  
Peiyu He ◽  
Rongjing Hong ◽  
Hua Wang ◽  
Cheng Lu
Keyword(s):  
Contact Angle ◽  
Maximum Stress ◽  
Ball Bearing ◽  
Three Dimensional ◽  
Contact Angles ◽  
Critical Parameters ◽  
Relative Slip ◽  
Contact State ◽  
Pitch Bearing ◽  
Bearing Raceway

In this paper, a three-dimensional numerical simulation (using ABAQUS) of the radial and tangential wear between a ball bearing and a raceway is presented. The aim was to study the influence of the contact angle between ball and raceway on the fretting. A range of contact angles was studied with critical parameters such as contact stress, relative slip, plastic deformation, and contact state. The model was validated against experimental data. The results show that with an increase in the contact angle, the area of maximum stress increases, the bearing capacity of the raceway decreases, and the maximum radial stress moves from the sub-surface to the raceway surface. The raceway surface is shown to be prone to peeling and wear, which reduces the service life of the raceway.

scholarly journals Human Gastric Mucosal Hydrophobicity Does dot Decrease with Helicobacter Pylori Infection or Chronological Age

2005 ◽  
Vol 19 (1) ◽  
pp. 37-41
Author(s):  
Mohammed S Al-Marhoon ◽  
Sheila Nunn ◽  
Roger W Soames
Keyword(s):  
Contact Angle ◽  
Helicobacter Pylori ◽  
Computer Software ◽  
Contact Angles ◽  
Chronological Age ◽  
Peptic Ulcers ◽  
Gastric Mucus ◽  
Gastric Diseases ◽  
Significant Difference ◽  
H Pylori

BACKGROUND AND AIMS: Infection with cytotoxin-associated gene A (cagA) Helicobacter pylori is associated with severe gastric diseases. Previous studies in humans have reported a decreased gastric hydrophobicity with H pylori infection. The aim of the present study was to differentiate between the effect of cagA+ and cagA- strains on gastric mucus hydrophobicity.METHODS: One hundred patients without peptic ulcers and not on medication were randomly recruited from endoscopy clinics; each patient had six biopsies. Contact angle measurements were performed using a goniometer assisted by computer software. H pylori status was assessed by histology, Campylobacter-like organism test and culture, and cagA+ status was determined by polymerase chain reaction.RESULTS: In age- and sex-matched patients, there was no significant difference (P=0.27) in contact angle between H pylori-positive (61±2.8°) and H pylori-negative patients (65.5±3.0°). There was also no significant difference (P=0.36) in contact angle among H pylori-negative, cagA- and cagA+ patients (65.5±3.0°, 58.6±3.6° and 63.4±4.9°, respectively). However, a trend of increased mean contact angles in cagA+ compared with cagA- and H pylori-negative patients was observed in patients 50 years and younger (68.3±8.3°, 61.1±6.1° and 63.6±2.2°, respectively; P=0.70) and in patients without atrophy (71.1±8°, 59.6±4° and 66±2°, respectively; P=0.30). In addition, there was no significant correlation between contact angles and patient age (r=0.104, P=0.306).CONCLUSIONS: The present study shows that H pylori infection and the chronological age have no effect on the gastric mucus hydrophobicity, but it highlights a trend of increased mucus hydrophobicity with cagA+ infection that needs to be supported by future studies.

scholarly journals Effective complex hydrophobizators for self-cleaning facade materials

2019 ◽  
Vol 97 ◽  
pp. 02035
Author(s):  
Mikhail Bruyako ◽  
Natalya Ivashchenko ◽  
Kristina Dobrina ◽  
Mikhail Moshnikov
Keyword(s):  
Contact Angle ◽  
Low Temperature ◽  
Nonequilibrium Plasma ◽  
Contact Angles ◽  
Fine Aggregate ◽  
Research Results ◽  
Wetting Contact Angle ◽  
Self Cleaning ◽  
Contact Angle Of Wetting ◽  
Temperature Nonequilibrium

In the work presented here, we present the research results of the effect of self-cleaning of surfaces. The methods of its achievement such as photocatalytic and the method of hydrophobization are considered. The known methods for determining the contact angle of wetting are used. An installation for generating a low-temperature nonequilibrium plasma was used to modify a fine aggregate. The contact angles of wetting obtained as a result of the use of various formulations of hydrophobizing suspensions are determined experimentally. A modification of the quartz filling matter was also carried out. Experiments have confirmed the technical effectiveness of hydrophobisers and the enhancement of their properties when dispersed fillers are used. Even higher values of wetting contact angle were achieved using a plasma-modified filling matter.

Electron Holographic Nano-Characterization of Gold Catalyst at Interface

2002 ◽  
Vol 727 ◽  
Author(s):  
S. Ichikawa ◽  
T. Akita ◽  
M. Okumura ◽  
M. Haruta ◽  
K. Tanaka
Keyword(s):  
Contact Angle ◽  
Titanium Oxide ◽  
Gold Catalyst ◽  
Three Dimensional ◽  
High Resolution Electron Microscopy ◽  
Electron Holography ◽  
Gold Particles ◽  
Oxide Support ◽  
The Mean ◽  
A Charge

AbstractThe catalytic properties of nanostructured gold catalyst are known to depend on the size of the gold particles and to be activated when the size decreases to a few nanometers. We investigated the size dependence of the three-dimensional nanostructure on the mean inner potential of gold catalysts supported on titanium oxide using electron holography and high-resolution electron microscopy (HREM). The contact angle of the gold particles on the titanium oxide tended to be over 90° for gold particles with a size of over 5 nm, and below 90° for a size of below 2 nm. This decreasing change in the contact angle (morphology) acts to increase the perimeter and hence the area of the interface between the gold and titanium oxide support, which is considered to be an active site for CO oxidation. The mean inner potential of the gold particles also changed as their size decreased. The value of the inner potential of gold, which is approximately 25 V in bulk state, rose to over 40 V when the size of the gold particles was less than 2 nm. This phenomenon indicates the existence of a charge transfer at the interface between gold and titanium oxide. The 3-D structure change and the inner potential change should be attributed to the specific electronic structure at the interface, owing to both the “nano size effect” and the “hetero-interface effect.”

Development of Mucoadhesive Buccal Drug Delivery System of Propranolol Hydrochloride Using Aster ericoides Mucilage

2020 ◽  
Vol 10 (2) ◽  
pp. 133-148
Author(s):  
Ankaj Kaundal ◽  
Pravin Kumar ◽  
Rajendra Awasthi ◽  
Giriraj T. Kulkarni
Keyword(s):  
Buccal Cavity ◽  
Three Dimensional ◽  
Hot Water ◽  
Fickian Diffusion ◽  
Aster Ericoides ◽  
Dimensional Network ◽  
Buccal Tablet ◽  
Significant Difference ◽  
Volunteer Group

Aim: The study was aimed to develop mucoadhesive buccal tablets using Aster ericoides leaves mucilage. Background : Mucilages are naturally occurring high-molecular-weight polyuronides, which have been extensively studied for their application in different pharmaceutical dosage forms. Objective: The objective of the present research was to establish the mucilage isolated from the leaves of Aster ericoides as an excipient for the formulation of the mucoadhesive buccal tablet. Method: The mucilage was isolated from the leaves of Aster ericoides by maceration, precipitated with acetone and characterized. Tablets were prepared using wet granulation technique and evaluated for various official tests. Results: The mucilage was found to be non-toxic on A-431 and Vero cell lines. It was insoluble but swellable in cold and hot water. The results indicate that mucilage can form a three-dimensional network. The pH of the mucilage (6.82 ± 0.13) indicated that it might be non-irritant to the buccal cavity. The mucilage was found to be free from microbes. The release of drug was by Fickian diffusion. The in vivo buccal tablet acceptance was 80%. No significant difference between the diastolic blood pressure of standard and Aster tablets treated volunteer group was recorded. Conclusion: The mucilage was found to be non-toxic on A-431 and Vero cell lines. It was insoluble but swellable in cold and hot water. The results indicate that mucilage can form a three-dimensional network. The pH of the mucilage (6.82 ± 0.13) indicated that it might be non-irritant to the buccal cavity. The mucilage was found to be free from microbes. The release of drug was by Fickian diffusion. The in vivo buccal tablet acceptance was 80%. No significant difference between the diastolic blood pressure of standard and Aster tablets treated volunteer group was recorded. Other: However, to prove the potency of the polymer, in vivo bioavailability studies in human volunteers are needed along with chronic toxicity studies in suitable animal models.

scholarly journals Efficacy evaluation of three-dimensional printing assisted osteotomy guide plate in accurate osteotomy of adolescent cubitus varus deformity

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Yuan-Wei Zhang ◽  
Xin Xiao ◽  
Wen-Cheng Gao ◽  
Yan Xiao ◽  
Su-Li Zhang ◽  
...  
Keyword(s):  
3D Printing ◽  
Blood Loss ◽  
Three Dimensional ◽  
Operation Time ◽  
Varus Deformity ◽  
Conventional Group ◽  
Intraoperative Blood Loss ◽  
Cubitus Varus ◽  
Guide Plate ◽  
Significant Difference

Abstract Background This present study is aimed to retrospectively assess the efficacy of three-dimensional (3D) printing assisted osteotomy guide plate in accurate osteotomy of adolescent cubitus varus deformity. Material and methods Twenty-five patients (15 males and 10 females) with the cubitus varus deformity from June 2014 to December 2017 were included in this study and were enrolled into the conventional group (n = 11) and 3D printing group (n = 14) according to the different surgical approaches. The operation time, intraoperative blood loss, osteotomy degrees, osteotomy end union time, and postoperative complications between the two groups were observed and recorded. Results Compared with the conventional group, the 3D printing group has the advantages of shorter operation time, less intraoperative blood loss, higher rate of excellent correction, and higher rate of the parents’ excellent satisfaction with appearance after deformity correction (P < 0.001, P < 0.001, P = 0.019, P = 0.023). Nevertheless, no significant difference was presented in postoperative carrying angle of the deformed side and total complication rate between the two groups (P = 0.626, P = 0.371). Conclusions The operation assisted by 3D printing osteotomy guide plate to correct the adolescent cubitus varus deformity is feasible and effective, which might be an optional approach to promote the accurate osteotomy and optimize the efficacy.

scholarly journals The Effect of Perioral Scan and Artificial Skin Markers on the Accuracy of Virtual Dentofacial Integration: Stereophotogrammetry Versus Smartphone Three-Dimensional Face-Scanning

2020 ◽  
Vol 18 (1) ◽  
pp. 229
Author(s):  
Hang-Nga Mai ◽  
Du-Hyeong Lee
Keyword(s):  
Three Dimensional ◽  
Laser Scanner ◽  
Statistical Analyses ◽  
Integrated Models ◽  
Image Integration ◽  
Positional Accuracy ◽  
Significant Difference ◽  
Face Scanning ◽  
Scanning Systems ◽  
Dimensional Face

This study evaluated the effects of different matching methods on the accuracy of dentofacial integration in stereophotogrammetry and smartphone face-scanning systems. The integration was done (N = 30) with different matching areas (n = 10), including teeth image only (TO), perioral area without markers (PN) and with markers (PM). The positional accuracy of the integrated models was assessed by measuring the midline linear deviations and incisal line canting between the experimental groups and laser scanner-based reference standards. Kruskal–Wallis and Mann–Whitney U tests were used for statistical analyses (α = 0.05). The PM method exhibited the smallest linear deviations in both systems; while the highest deviations were found in the TO in stereophotogrammetry; and in PN in smartphone. For the incisal line canting; the canting degree was the lowest in the PM method; followed by that in the TO and the PN in both systems. Although stereophotogrammetry generally exhibited higher accuracy than the smartphone; the two systems demonstrated no significant difference when the perioral areas were used for matching. The use of perioral scans with markers enables accurate dentofacial image integration; however; cautions should be given on the accuracy of the perioral image obtained without the use of markers.

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