scholarly journals Needleless Electrospinning Using a Flat Wheel Spinneret

2017 ◽  
Vol 12 (3) ◽  
pp. 155892501701200 ◽  
Author(s):  
Usman Ali ◽  
Amir Abbass ◽  
Furqan Khurshid ◽  
Sarmad Aslam ◽  
Abdul Waqar
Keyword(s):  
Electric Field ◽  
Production Rate ◽  
Mass Production ◽  
Solution Concentration ◽  
Poly Vinyl Alcohol ◽  
Operating Parameters ◽  
Fiber Morphology ◽  
Sequence Generation ◽  
Wide Range ◽  
The Impact

Nanofibers have a wide range of applications, however; the mass production of nanofibers is still an obstacle to wider industrial application. In this paper, a flat wheel was used as a spinneret for production of poly (vinyl) alcohol nanofibers. Electric field comparative analysis was done between the flat wheel and other spinnerets such as a cylinder, disk and ring. It was found the flat wheel falls between the cylinder and disk and ring spinnerets. Sequence generation of polymer jets was observed from the both edges of the wheel and as well as from the surface of the wheel. The impact of operating parameters on fiber morphology was studied and it was found that smooth, uniform nanofibers with diameter around 350nm could be produced by using this spinneret. Influence of strength of applied electric field and solution concentration on the production rate was also examined and it was noted that the production rate of nanofibers using a flat wheel spinneret is several times higher than that obtained using a conventional needle electrospinning setup.

Tuning the Mechanical and Geometric Properties of Electrochemically Aligned Collagen Threads Towards Applications in Biohybrid Robotics

2021 ◽  
Author(s):  
Wenhuan Sun ◽  
Jason Paulovich ◽  
Victoria Webster-Wood
Keyword(s):  
Tensile Modulus ◽  
Solution Concentration ◽  
Cross Sectional ◽  
Geometric Properties ◽  
Wide Range ◽  
Crosslinker Concentration ◽  
High Degree ◽  
The Impact ◽  
Fabrication Parameters ◽  
Manufacturing Parameters

Abstract Electrochemically Aligned Collagen (ELAC) threads fabricated by the isoelectric focusing (IF) of collagen have previously shown potential in tissue engineering and more recently in the fabrication of biohybrid robot structures. For applications in biohybrid robotics, ELAC structures are needed that are both robust and compliant enough to facilitate muscle actuation. However, studies on the effects of IF parameters, and the interactions of such fabrication parameters, on the mechanical and geometric properties of resulting ELAC threads have not been previously found in literature. Understanding the impact of these manufacturing parameters on the material properties is critical to facilitate biohybrid robot design. In this study, the effects of IF duration, IF voltage, and collagen solution concentration were investigated and showed statistically significant effects on adjusting ELAC properties via single-factor experiments. The interactions between parameters exhibited significant joint effects on ELAC property tuning through two-factor experiments. Scanning electron microscopy and 2,4,6-trinitrobenzenesulfonic assays revealed the correlation between high mechanical properties and a combination of low porosity and high degree of crosslinking. By simply tuning IF parameters without changing other fabrication steps, such as crosslinker concentration, ELAC threads with a wide range of mechanical and geometric properties were fabricated. The average tensile modulus of the resulting ELAC threads ranged from 198±90 to 758±138 MPa. The average cross-sectional area ranged from 7756±1000 to 1775±457 µm2. The resultant mapping between IF parameters and ELAC thread properties enabled the production of strong and flexible threads with customizable properties.

Enhanced optical performance for a reduction stepper to meet the challenges for advanced packaging applications

2015 ◽  
Vol 2015 (1) ◽  
pp. 000879-000884 ◽  
Author(s):  
James E. Webb ◽  
Philippe Cochet
Keyword(s):  
Mass Production ◽  
Partial Coherence ◽  
Optical Parameters ◽  
Optical Performance ◽  
Modeling Tools ◽  
Wide Range ◽  
Advanced Packaging ◽  
And Performance ◽  
The Impact ◽  
Image Performance

Mass production of high density interconnects using 3D and 2.5D technologies requires optimal lithography processing with certain optical properties. This paper discusses the modifications and performance changes made to a step-and-repeat camera that have improved the tool utilization. New options are available that enhance the performance and provide the best match to a wide range of resist requirements to attain optimal fidelity and higher throughput. Changes in illumination power, partial coherence and wavelength bandwidth are discussed. Modeling tools are used to predict the improvement and guide the process. Changed optical parameters that impact the image performance are modeled and compared to resist images evaluated. The illumination power increases are used to calculate the impact these changes have on increased throughput. Examples will show modeled and measured improvements achieved.

scholarly journals New Polymers for Needleless Electrospinning from Low-Toxic Solvents

Nanomaterials ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 52 ◽  
Author(s):  
Martin Wortmann ◽  
Natalie Frese ◽  
Lilia Sabantina ◽  
Richard Petkau ◽  
Franziska Kinzel ◽  
...  
Keyword(s):  
Vinyl Alcohol ◽  
New Technology ◽  
Acrylonitrile Butadiene Styrene ◽  
Water Soluble ◽  
Poly Vinyl Alcohol ◽  
Fiber Morphology ◽  
Water Soluble Polymers ◽  
Wide Range ◽  
Solvent Additive ◽  
Low Toxic

Electrospinning is a new technology whose scope is gradually being developed. For this reason, the number of known polymer–solvent combinations for electrospinning is still very low despite the enormous variety of substances that are potentially available. In particular, electrospinning from low-toxic solvents, such as the use of dimethyl sulfoxide (DMSO) in medical technology, is rare in the relevant scientific literature. Therefore, we present in this work a series of new polymers that are applicable for electrospinning from DMSO. From a wide range of synthetic polymers tested, poly(vinyl alcohol) (PVOH), poly(2ethyl2oxazolene) (PEOZ), and poly(vinylpyrrolidone) (PVP) as water-soluble polymers and poly(styrene-co-acrylonitrile) (SAN), poly(vinyl alcohol-co-ethylene) (EVOH), and acrylonitrile butadiene styrene (ABS) as water-insoluble polymers were found to be suitable for the production of nanofibers. Furthermore, the influence of acetone as a volatile solvent additive in DMSO on the fiber morphology of these polymers was investigated. Analyses of the fiber morphology by helium ion microscopy (HIM) showed significantly different fiber diameters for different polymers and a reduction in beads and branches with increasing acetone content.

Tailored Nanofiber Morphologies Using Modulated Electrospinning for Biomedical Applications

2002 ◽  
Vol 736 ◽  
Author(s):  
David Y. Lin ◽  
Michael A. Johnson ◽  
Richard A. Vohden ◽  
Deborah Chen ◽  
David C. Martin
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Fiber Diameter ◽  
Field Potential ◽  
Electrospun Nanofibers ◽  
Fiber Formation ◽  
Fiber Morphology ◽  
Wide Range ◽  
Oscillating Electric Field ◽  
Deposition Distance

ABSTRACTThe process of electrostatic fiber formation, or electrospinning, was used to generate polymer filaments with diameters in the 50–200 nm range. We have shown that in addition to process parameters such as solution concentration, spinning voltage, and deposition distance, an oscillating electric field can also influence the morphology of the electrospun nanofibers. Specifically, effects of the oscillating field strength and frequency, spinning voltage, and deposition distance on fiber diameter as well as size and number density of the beaded structures in the fibrous thin films are examined.The results of our study demonstrate that modulated field potential produces more uniform fibers. Increasing either the oscillating field strength or frequency yields more uniform average fiber diameter. Also, for systems with the “beads on a string” fiber morphology, increasing the oscillating field strength produces more uniform bead sizes.The ability to tailor fiber morphology using an oscillating electric field has promising implications in a wide range of applications including controlled-release drug delivery systems and biocompatible implants. We show here the potential of using electrospun nanofibers as a porous template for growing fuzzy conductive polymers to modify the surface of a neural recording microelectrode device. These hairy nanostructures can increase signal transport and mediate the mechanical property differences between the device and the soft brain tissues.

Rapid Removal of Methylene Blue in Water Using Polymer-Based Biochar Nanocomposite-Coated Filters

2021 ◽  
Vol 324 ◽  
pp. 116-124
Author(s):  
Edgar Clyde R. Lopez ◽  
Nathaniel M. Saporsantos ◽  
William Ven R. Magbalon ◽  
Richard C. Aquino ◽  
Miguel Lawrence Keith S.J. Celebre ◽  
...  
Keyword(s):  
Dip Coating ◽  
Operating Conditions ◽  
Poly Vinyl Alcohol ◽  
Maximum Sorption Capacity ◽  
Wide Range ◽  
Maximum Sorption ◽  
Initial Ph ◽  
Coating Method ◽  
Dip Coating Method ◽  
The Impact

In this study, the effectiveness of novel nanocomposite-coated filters consisting of biochar (BC) functionalized with sodium alginate (SA) and poly (vinyl alcohol) (PVA) was investigated for methylene (MB) blue removal. The filters were fabricated via a dip-coating method and SEM and FTIR spectroscopy confirmed the successful coating of the filters. The impact of the nanocomposite formulation and the operating parameters (initial pH and MB concentration) on the performance of the coated filters were studied. A nanocomposite composition consisting of 1.0 wt.% SA, 2.0 wt.% PVA, and 1000 ppm BC were found to be optimum, reaching as high as 96.51% MB removal. The fabricated filters were determined to be robust over a wide range of pH and initial MB concentrations. The Sips isotherm model proved to be the best-fit model for MB adsorption, where chemisorption dominates at low MB concentrations, while physisorption dominates at high MB concentrations. The filters have a maximum sorption capacity of 54.5198 mg g-1 and showed good reusability. Overall, our synthesized SA/PVA/BC-coated filters can be used to effectively remove dyes in wastewater over a wide range of operating conditions.

Macromolecule/Polymer-Iodine Complexes: An Update

2019 ◽  
Vol 12 (3) ◽  
pp. 174-233
Author(s):  
Saad Moulay
Keyword(s):  
Graphene Oxide ◽  
Nuclear Power ◽  
Power Plants ◽  
Molecular Iodine ◽  
Poly Vinyl Alcohol ◽  
Complexing Agents ◽  
Iodine Doping ◽  
Wide Range ◽  
The Impact ◽  
Iodine Complexes

The great chemical affinity of molecular iodine towards several macromolecules and innumerable polymers allows the formation of macromolecule/polymer-iodine complexes, usually commensurate with the desired uses and applications. In many instances, the formation of such complexes occurs through a charge-transfer mechanism. The strength of the ensued complex is more accentuated by the presence of heteroatoms (nitrogen, oxygen, sulfur) and the π-conjugation induced moieties within the chemical structure of the polymer. A wide range of polymers with high specific surface areas and large total pore volumes are excellent candidates for iodine adsorption, suggesting their use in the removal of radioactive iodine in nuclear power plants. The recent results of iodine uptake by polysaccharides such as starch, chitin, chitosan, alginate, and cellulose are but novelties. Complexing vinyl polymers such as poly(N-vinyl-2-pyrrolidone), poly(vinyl pyridine), poly(vinyl alcohol), poly(vinyl chloride), poly(acrylonitrile), and polyacrylics, with molecular iodine revealed special chemistry, giving rise to polyiodide ions (In -) as the actual complexing agents. Carbon allotropes (graphene, graphene oxide, carbon nanotubes, amorphous carbons) and polyhydrocarbons are prone to interact with molecular iodine. The treatment of a broad set of polymers and macromolecules with molecular iodine is but a doping process that ends up with useful materials of enhanced properties such conductivity (electrical, ionic, thermal); in some cases, the obtained materials were of engineering applications. Complexation and doping materials with iodine are also aimed at ensuring the antimicrobial activity, particularly, for those intended for medical uses. In several cases, the impact of the iodine doping of polymer is the alteration of its morphology, as is the case of the disruption of the graphitic morphology of the graphene or graphene oxide.

scholarly journals Spatial Positioning and Operating Parameters of a Rotary Bell Sprayer: 3D Mapping of Droplet Size Distributions

Fluids ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 165 ◽  
Author(s):  
Adnan Darwish Ahmad ◽  
Binit B. Singh ◽  
Mark Doerre ◽  
Ahmad M. Abubaker ◽  
Masoud Arabghahestani ◽  
...  
Keyword(s):  
Droplet Size ◽  
Flow Rate ◽  
Rotational Speed ◽  
Operating Parameters ◽  
Size Distributions ◽  
Theoretical Formulation ◽  
Wide Range ◽  
Droplet Sizes ◽  
Spatial Positioning ◽  
The Impact

In this study, we evaluated the fundamental physical behavior during droplet formation and flow from a rotary bell spray in the absence of an electrostatic field. The impact of a wide range of operating parameters of the rotary bell sprayer, such as flow rates, rotational speeds, and spatial positioning, on droplet sizes and size distributions using a three-dimensional (3-D) mapping was studied. The results showed that increasing the rotational speed caused the Sauter mean diameter of the droplets to decrease while increasing flow rate increased the droplet sizes. The rotational speed effect, however, was dominant compared to the effect of flow rate. An increase in droplet size radially away from the cup was noted in the vicinity of the cup, nevertheless, as the lateral distances from the cup and rotational speed were increased, the droplet sizes within the flow field became more uniform. This result is of importance for painting industries, which are looking for optimal target distances for uniform painting appearance. Furthermore, the theoretical formulation was validated with experimental data, which provides a wider range of applicability in terms of environment and parameters that could be tested. This work also provides an abundance of measurements, which can serve as a database for the validation of future droplet disintegration simulations.

Electron sources: Past, present, and future

1993 ◽  
Vol 51 ◽  
pp. 764-765
Author(s):  
David C Joy
Keyword(s):  
Glass Tube ◽  
Source Size ◽  
Electron Gun ◽  
Operating Parameters ◽  
Operational Parameters ◽  
Electron Sources ◽  
Difficult Decision ◽  
Probe Size ◽  
Wide Range ◽  
Overall Performance

The electron source is the most important component of the Scanning electron microscope (SEM) since it is this which will determine the overall performance of the machine. The gun performance can be described in terms of quantities such as its brightness, its source size, its energy spread, and its stability and, depending on the chosen application, any of these factors may be the most significant one. The task of the electron gun in an SEM is, in fact, particularly difficult because of the very wide range of operational parameters that may be required e.g a variation in probe size of from a few angstroms to a few microns, and a probe current which may go from less than a pico-amp to more than a microamp. This wide range of operating parameters makes the choice of the optimum source for scanning microscopy a difficult decision.Historically, the first step up from the sealed glass tube ‘cathode ray generator’ was the simple, diode, tungsten thermionic emitter.

THE IMPACT OF LEADERSHIP PRACTICES TO TEAM MEMBERS’ SATISFACTION

2009 ◽  
Vol 8 (1) ◽  
Author(s):  
Chalimah .
Keyword(s):  
Conflict Resolution ◽  
Leadership Practices ◽  
Hotel Industry ◽  
Leader Behavior ◽  
Team Leader ◽  
Shop Floor ◽  
Team Members ◽  
Top Executives ◽  
Wide Range ◽  
The Impact

eamwork is becoming increasingly important to wide range of operations. It applies to all levels of the company. It is just as important for top executives as it is to middle management, supervisors and shop floor workers. Poor teamwork at any level or between levels can seriously damage organizational effectiveness. The focus of this paper was therefore to examine whether leadership practices consist of team leader behavior, conflict resolution style and openness in communication significantly influenced the team member’s satisfaction in hotel industry. Result indicates that team leader behavior and the conflict resolution style significantly influenced team member satisfaction. It was surprising that openness in communication did not affect significantly to the team members’ satisfaction.

Stress, anxiety, depression and burnout in frontline health care workers during COVID-19 pandemic: a brief systematic review and new data from Russia

2021 ◽  
Author(s):  
Ekaterina Mosolova ◽  
Dmitry Sosin ◽  
Sergey Mosolov
Keyword(s):  
Risk Factors ◽  
Systematic Review ◽  
Female Gender ◽  
Assessment Tools ◽  
Care Workers ◽  
Younger Age ◽  
Wide Range ◽  
Associated Risk Factors ◽  
Anxiety Depression ◽  
The Impact

During the COVID-19 pandemic, healthcare workers (HCWs) have been subject to increased workload while also exposed to many psychosocial stressors. In a systematic review we analyze the impact that the pandemic has had on HCWs mental state and associated risk factors. Most studies reported high levels of depression and anxiety among HCWs worldwide, however, due to a wide range of assessment tools, cut-off scores, and number of frontline participants in the studies, results were difficult to compare. Our study is based on two online surveys of 2195 HCWs from different regions of Russia during spring and autumn epidemic outbreaks revealed the rates of anxiety, stress, depression, emotional exhaustion and depersonalization and perceived stress as 32.3%, 31.1%, 45.5%, 74.2%, 37.7% ,67.8%, respectively. Moreover, 2.4% of HCWs reported suicidal thoughts. The most common risk factors include: female gender, nurse as an occupation, younger age, working for over 6 months, chronic diseases, smoking, high working demands, lack of personal protective equipment, low salary, lack of social support, isolation from families, the fear of relatives getting infected. These results demonstrate the need for urgent supportive programs for HCWs fighting COVID-19 that fall into higher risk factors groups.

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