Electrospun Nanofibers for Label-Free Sensor Applications

Electrospinning is a simple, low-cost and versatile method for fabricating submicron and nano size fibers. Due to their large surface area, high aspect ratio and porous structure, electrospun nanofibers can be employed in wide range of applications. Biomedical, environmental, protective clothing and sensors are just few. The latter has attracted a great deal of attention, because for biosensor application, nanofibers have several advantages over traditional sensors, including a high surface-to-volume ratio and ease of functionalization. This review provides a short overview of several electrospun nanofibers applications, with an emphasis on biosensor applications. With respect to this area, focus is placed on label-free sensors, pertaining to both recent advances and fundamental research. Here, label-free sensor properties of sensitivity, selectivity, and detection are critically evaluated. Current challenges in this area and prospective future work is also discussed

Bidirectional and Stretchable Piezoresistive Sensors Enabled by Multimaterial 3D Printing of Carbon Nanotube/Thermoplastic Polyurethane Nanocomposites

Fabricating complex sensor platforms is still a challenge because conventional sensors are discrete, directional, and often not integrated within the system at the material level. Here, we report a facile method to fabricate bidirectional strain sensors through the integration of multiwalled carbon nanotubes (MWCNT) and multimaterial additive manufacturing. Thermoplastic polyurethane (TPU)/MWCNT filaments were first made using a two-step extrusion process. TPU as the platform and TPU/MWCNT as the conducting traces were then 3D printed in tandem using multimaterial fused filament fabrication to generate uniaxial and biaxial sensors with several conductive pattern designs. The sensors were subjected to a series of cyclic strain loads. The results revealed excellent piezoresistive responses with cyclic repeatability in both the axial and transverse directions and in response to strains as high as 50%. It was shown that the directional sensitivity could be tailored by the type of pattern design. A wearable glove, with built-in sensors, capable of measuring finger flexure was also successfully demonstrated where the sensors are an integral part of the system. These sensors have potential applications in wearable electronics, soft robotics, and prosthetics, where complex design, multi-directionality, embedding, and customizability are demanded

Intravenous Haloperidol versus Midazolam in Management of Conversion Disorder; a Randomized Clinical Trial

Introduction: Conversion disorder is a condition in which the patient shows psychological stress in physical ways. This study aimed to compare the effects of haloperidol versus midazolam in patients with conversion disorder.Methods: This double-blind randomized clinical trial was conducted on patients with conversion disorder who had presented to the emergency department, throughout 2015. Patients were randomly divided into two groups and were either treated with 2.5 mg of intravenous (IV) haloperidol or 2.5 mg of IV midazolam. Recovery rate, time to recovery, and side effects of both drugs 1 hour, 24 hours, and 1 week after treatment were compared using SPSS19.Results: 140 patients were divided into two groups of 70. There were no significant differences between the groups regarding the baseline characteristics. 12 (17.1%) patients who were treated with IV haloperidol experienced drug side effects within 1 hour and 12 (17.1%) within 24 hours, while only 3 (4.3%) patients in IV midazolam experienced side-effects within 1 hour after drug administration (p = 0.026).  The symptoms of the disease subsided in 45 (success rate: 64.3%) patients in midazolam and in 64 (success rate: 91.5%) participants in haloperidol group (P<0.001). Mean recovery time was 31.24 ± 7.03 minutes in IV midazolam and 30.53 ± 7.11 minutes in IV haloperidol group (p = 0.592). Absolute risk reduction (ARR) of treating patients with haloperidol compared to midazolam is about 27%.Conclusion: The response of patients to treatment with haloperidol is clearly better than midazolam. Although more transient and minor side-effects were observed in the group treated with haloperidol compared to midazolam group, serious side-effects were rare for both treatments

Implementing Bounded Linear Programming and Analytical Network Process Fuzzy Models to Motivate Employees: a Case Study

In this research, the factors affectinguniversity employees’ motivation and productivity are identified and classified in seven groups; the impact of each motivation factor on the productivity is presented by ANP fuzzy model.Eight universities in Iran were analyzed in this research work. The aim of this study is to explore the productivity of employees. This paper attempts to give new insights intodesigning the portfolio factors, motivating employees for productivity improvement by implementing BLP and ANP fuzzy models.The research results show that there is a positive and significant relationship among reward system, motivation factors, and human resources productivity. In addition, among the options of reward system, the factors of internal (inherent) reward, non-financial external reward, and financial external reward had the highestimpact on increasing motivation and productivity factors. At the next stage, a BLP model is designed according to the importance and impact of each reward system option on motivation and productivity factors and organization limitations, including budget, facilities, and conditions to design portfolio factors motivating employees with the aim of improving productivity. The research results show that actualizing performance evaluation, receiving the feedback from the results of doing tasks by different ways, providing an opportunity for all employees to progress, coordination between job specifications and employees’ abilities, and a manager competency are very critical for improving the organization productivity

Thermoplastic polyurethane flexible capacitive proximity sensor reinforced by CNTs for applications in the creative industries

Wearable sensing platforms have been rapidly advanced over recent years, thanks to numerous achievements in a variety of sensor fabrication techniques. However, the development of a flexible proximity sensor that can perform in a large range of object mobility remains a challenge. Here, a polymer-based sensor that utilizes a nanostructure composite as the sensing element has been presented for forthcoming usage in healthcare and automotive applications. Thermoplastic Polyurethane (TPU)/Carbon Nanotubes (CNTs) composites are capable of detecting presence of an external object in a wide range of distance. The proximity sensor exhibits an unprecedented detection distance of 120 mm with a resolution of 0.3%/mm. The architecture and manufacturing procedures of TPU/CNTs sensor are straightforward and performance of the proximity sensor shows robustness to reproducibility as well as excellent electrical and mechanical flexibility under different bending radii and over hundreds of bending cycles with variation of 4.7% and 4.2%, respectively. Tunneling and fringing effects are addressed as the sensing mechanism to explain significant capacitance changes. Percolation threshold analysis of different TPU/CNT contents indicated that nanocomposites having 2 wt% carbon nanotubes are exhibiting excellent sensing capabilities to achieve maximum detection accuracy and least noise among others. Fringing capacitance effect of the structure has been systematically analyzed by ANSYS Maxwell (Ansoft) simulation, as the experiments precisely supports the sensitivity trend in simulation. Our results introduce a new mainstream platform to realize an ultrasensitive perception of objects, presenting a promising prototype for application in wearable proximity sensors for motion analysis and artificial electronic skin

Materials with enhanced adhesive properties based on acrylonitrile-butadiene-styrene (ABS)/thermoplastic polyurethane (TPU) blends for fused filament fabrication (FFF)

In the current work, we prepared a novel material suitable for additive manufacturing by using acrylonitrilebutadiene- styrene (ABS) copolymer as matrix and a thermoplastic polyurethane (TPU) as additive. Conditions for successful printing via fused filament fabrication (FFF)were optimized for the ABS:TPU blends. Compatibility of ABS and TPU in the blends was studied by Fourier-transformed infrared (FTIR) spectroscopy, showing the appearance of new supramolecular interactions via hydrogen bonding. Compositional studies were carried out by confocal Ramanmicroscopy and atomic forcemicroscopy (AFM), demonstrating the good compatibility between the two compounds. Mechanical and adhesive properties were studied by 3D-printing different normalized test specimens in different directions. Itwas shown that blends containing 10–20wt% TPU led to enhanced adhesion between layerswithout loss in yield strength,while 30wt% TPU led to a good adhesion between layers and to the printing platform when printing at room temperature

Functional properties of sodium and calcium caseinate antimicrobial active films containing carvacrol

Active edible films were prepared by adding carvacrol into sodium caseinate (SC) and calcium caseinate (CC) matrices plasticized with two different glycerol concentrations (25 and 35 wt%) prepared by solvent casting. Functional characterisation of these bio-films was carried out by determination of some of their physico-chemical properties, such as colour, transparency, oxygen barrier, wettability, dye permeation properties and antibacterial effectiveness against Gram negative and Gram positive bacteria. All films exhibited good performance in terms of optical properties in the CIELab space showing high transparency. Carvacrol was able to reduce CC oxygen permeability and slightly increased the surface hydrophobicity. Dye diffusion experiments were performed to evaluate permeation properties. The diffusion of dye through films revealed that SC was more permeable than CC. The agar diffusion method was used for the evaluation of the films antimicrobial effectiveness against Escherichia cell and Staphylococcus aureus. Both SC and CC edible films with carvacrol showed inhibitory effects on both bacteria. (C) 2013 Elsevier Ltd. All rights reserved.This research was supported by the Ministry of Science and Innovation of Spain through the projects MAT2011-28468-C02-01, MAT2011-28468-C02-02 and HP2008-0080. M.P. Arrieta thanks Fundacion MAPFRE for "Ignacio Hernando de Larramendi 2009-Medio Ambiente" fellowship (MAPFRE-IHL-01). Authors thank Ferrer Alimentacion S.A., for providing the caseinates powders.Arrieta, MP.; Peltzer, MA.; López Martínez, J.; Garrigós Selva, MDC.; Valente, AJM.; Jimenez Migallon, A. (2014). Functional properties of sodium and calcium caseinate antimicrobial active films containing carvacrol. Journal of Food Engineering. 121:94-101. https://doi.org/10.1016/j.jfoodeng.2013.08.015S9410112

Characterization of interlayer adhesion and fracture resistance in additively manufactured thermoplastic parts

The quality of fused deposition modeling (FDM) 3D printed parts are primarily influenced by the process conditions and mesostructural features. This study aims to establish the relationships between the process parameters/mesostructural features and the fracture resistance of printed parts. A fracture-mechanics-based methodology is developed and used to characterize the interlayer adhesion strength and the overall fracture resistance of FDM 3D printed materials. Double cantilever beam (DCB) specimens of acrylonitrile butadiene styrene (ABS) were designed and printed with a precrack at the layers' interface. Specimens were printed at different nozzle and bed temperatures, and with different layer heights and layer widths. The DCBs were loaded in an opening mode and the load-displacement curves were synchronized with the optical visualization of the crack tip to detect the critical load at the crack initiation. A finite element model, coupled with J-integral method and fracture surface analysis was then developed to obtain the apparent fracture resistance (Jcr,a) and the interlayer fracture resistance (Jcr,i), as a measure of the interlayer adhesion. The results indicated that nozzle temperature has the most significant effect on both the apparent and the interlayer fracture resistances of FDM printed materials. The apparent fracture resistance increased by ~38% with 20°C increase in the nozzle temperature from 220°C to 240°C. Similarly, the interlayer fracture resistance also increased by ~15% from 3391.04±69.83 to 3907.54±143.13 J/m2 . Bed temperature also affected the fracture resistance albeit with a milder rate. The interlayer fracture resistance increased by 7.6% from 3527.91±221.16 to 3798.54±204.04 J/m2 by a 20°C increase in the bed temperature from 85 to 105°C. The layer width appeared to be a less significant factor, compared to the nozzle and bed temperatures. Furthermore, a huge drop from 2130.73±108.37 to 731.82±47.22 J/m2 was observed in the apparent fracture resistance of printed ABS samples when the layer height was increased from 0.1 mm to 0.3 mm. This significant decrease was attributed to the mesostructure consideration through scanning electron microscopy and density investigation. Overall, this work proposes a methodology to quantify the fracture resistance of layer-by-layer printed materials and provides insights toward the design and analysis of printed materials for structural and functional applications

Improvement of DEA approach for clustering credit rating of customer in banks

Competition between the managers of industrial and service organizations to provide their financial needs and credit facilities via the bank's loan is growing daily. Other hand, financial resources and credit of banks and financial institutions to provide accommodations to applicants is limit. Accordingly the optimal allocation of limit financial resources with the aim of making the maximum value for their investment is a necessity. In this study, the validation criteria to identify applicants receive legal facilities using improved techniques of data envelopment analysis (DEA), an efficient method for legal clients of categories is presented. Improved techniques of DEA by defining a perfect organization in each time of runs that cause to reduce of computing and operation speed of decision-making and improved available DEA method. The improved DEA model also offers a short, direct and dynamic route to achieve more efficiency in each of efficient and inefficient the companies. Prioritizations provided by the improved DEA method in all case studies, were equal with priorities of the available DEA approach

Thermoplastic Polyurethane/Lead Zirconate Titanate/Carbon Nanotube Composites with Very High Dielectric Permittivity and Low Dielectric Loss

Ternary composites of flexible thermoplastic polyurethane (TPU), lead zirconate titanate (PZT), and multiwalled carbon nanotubes (MWCNTs) with very high dielectric permittivity (εr) and low dielectric loss (tan δ) are reported. To assess the evolution of dielectric properties with the interactions between conductive and dielectric fillers, composites were designed with a range of content for PZT (0–30 vol%) and MWCNT (0–1 vol%). The microstructure was composed of PZT-rich and segregated MWCNT-rich regions, which could effectively prevent the formation of macroscopic MWCNT conductive networks and thus reduce the high ohmic loss. Therefore, εr increased by a maximum of tenfold, reaching up to 166 by the addition of up to 1 vol% MWCNT to TPU/PZT. More importantly, tan δ remained relatively unchanged at 0.06–0.08, a similar range to that of pure TPU. εr/tan δ ratio reached 2870 at TPU/30 vol% PZT/0.5 vol% MWCNT, exceeding most of the reported values. This work demonstrates the potential of three-phase polymer/conductive filler/dielectric filler composites for efficient charge storage applications