Synthesis and study of electrical properties of polyaniline and polyester nanocomposite

In this study, pure polyaniline (PANI) and PANI/polyester nanocomposites (wt % 10, 20 and 30) of thickness 10 mm have been synthesized by co-precipitation method to investigate their electrical properties. Pure PANI and its composites are then characterized using SEM, FTIR, DSC, I-V Hall and dielectric techniques. From SEM, it is observed that the particles are spherical and lying in range of micron order. To find out the nature of chemical bonds, FTIR analysis and thermal characterization (DSC) are performed. From the I-V curve, the calculated values of conductance of prepared pure PANI and PANI/PET (wt % 10, 20 and 30 nanocomposite) are obtained as 3.78×10-7, 9.7933×10-7, 9.584×10-8 and 9.882×10-9 ohm-1 respectively. From Hall measurement, electrical conductivity of pure PANI and PANI/PET (wt % 10, 20 and 30) nanocomposite is found 49.26 ×10-6, 13.82 ×10-6, 40.6 ×10-7 and 18.761 ×10-7 Ω-1cm-1 respectively. Dielectric study of PANI/PET reveals downturn in the dielectric constant value with increased frequency. The electrical resistivity of the PANI/PET nanocomposite shows high anti-static efficiency

Expanding the Angle of Incidence Tolerance of Unclonable Anticounterfeiting Labels Based on Microlens Arrays and Luminescent Microparticles

Unclonable anticounterfeiting labels can be based on micrometer-scale randomness created by stochastic processes like the distribution of luminescent microparticles in a transparent layer. Adding a microlens array to the layer can simplify the hardware needed for authentication in that magnification is no longer required. The bright point-pattern generated under light-emitting diode illumination can be captured by a standard digital camera. Shifting the angle of incidence (AOI) relocates the microlens foci changing the bright point-pattern. This provides unclonability, as several distinct bright point patterns at different AOI can be required for authentication. However, it also imposes technical requirements for the authentication setup in terms of the tolerance with which the AOI must be controlled. Herein, the AOI tolerance, the deviation of angle between reference and test image for which sufficiently similar bright point patterns are recorded that they are considered matching by the authentication algorithm, is investigated. Using microlens arrays with a focal length of 550 μm, the average size of the phosphor particle was varied from 9 ± 1 to 32.5 ± 2 μm, resulting in a relaxation of tolerance from 0.8° to 3.6°. Methods to further increase the AOI tolerance and facilitate the practical implementation of these labels are discussed

Synthesis and study of electrical properties of polyaniline and polyester nanocomposite

215-219In this study, pure polyaniline (PANI) and PANI/polyester nanocomposites (wt % 10, 20 and 30) of thickness 10 mm have been synthesized by co-precipitation method to investigate their electrical properties. Pure PANI and its composites are then characterized using SEM, FTIR, DSC, I-V Hall and dielectric techniques. From SEM, it is observed that the particles are spherical and lying in range of micron order. To find out the nature of chemical bonds, FTIR analysis and thermal characterization (DSC) are performed. From the I-V curve, the calculated values of conductance of prepared pure PANI and PANI/PET (wt % 10, 20 and 30 nanocomposite) are obtained as 3.78×10-7, 9.7933×10-7, 9.584×10-8 and 9.882×10-9 ohm-1 respectively. From Hall measurement, electrical conductivity of pure PANI and PANI/PET (wt % 10, 20 and 30) nanocomposite is found 49.26 ×10-6, 13.82 ×10-6, 40.6 ×10-7 and 18.761 ×10-7 Ω-1cm-1 respectively. Dielectric study of PANI/PET reveals downturn in the dielectric constant value with increased frequency. The electrical resistivity of the PANI/PET nanocomposite shows high anti-static efficiency

Bursting behavior of polyester needle-punched filter fabrics

253-259The effect of fabric weight, depth of needle penetration and needling density on bursting strength of needle-punched nonwoven filter fabrics prepared from virgin and recycled polyester fibres has been studied. The effect of fabric parameters on bursting behavior trend is found similar in both the virgin and the recycled polyester filter fabric samples. There is considerable fall in bursting strength of recycled polyester fabrics as compared to that in virgin one, under high fabric weight and needling density. Interestingly, it has been found that the recycled polyester filter fabric shows 3.584% lesser strength (average value of all samples) than the virgin polyester filter fabric, which signifies the use of recycled polyester filter wherever applicable, considering the recyclability and sustainability aspects

Bursting behavior of polyester needle-punched filter fabrics

The effect of fabric weight, depth of needle penetration and needling density on bursting strength of needle-punched nonwoven filter fabrics prepared from virgin and recycled polyester fibres has been studied. The effect of fabric parameters on bursting behavior trend is found similar in both the virgin and the recycled polyester filter fabric samples. There is considerable fall in bursting strength of recycled polyester fabrics as compared to that in virgin one, under high fabric weight and needling density. Interestingly, it has been found that the recycled polyester filter fabric shows 3.584% lesser strength (average value of all samples) than the virgin polyester filter fabric, which signifies the use of recycled polyester filter wherever applicable, considering the recyclability and sustainability aspects

Unclonable Anti-Counterfeiting Labels Based on Microlens Arrays and Luminescent Microparticles

Micron-scale randomness during manufacturing can create unique and unclonable anti-counterfeiting labels. The security of such labels typically comes at the expense of complex hardware being required for authentication. This work demonstrates unclonable labels that can be authenticated using simple hardware such as a standard light-emitting diode and smartphone camera. These labels consist of a microlens array laminated to a luminescent-microparticle-doped polymer film, and thereby present a new method of making microscopic particle distributions visible on the macroscopic scale. The current novel design offers two significant practical advantages: 1) use of an incoherent source; and 2) authentication independent of the detector position. A comparison of 100 test images against 100 different reference images (total of 10,000 comparisons out of which 100 should authenticate and 9900 should not), demonstrates that authentication is robust with an estimated probability of a false positive on the order of 10$^{-15}$. Finally, a proof-of-concept is demonstrated through successful authentication of a label by a single smartphone, simultaneously providing both excitation and detection on the front side of the label

Smartphone Authentication of Unclonable Anticounterfeiting Labels based on a Microlens Array atop a Microphosphor‐Doped Layer

A phosphor-particle-loaded microlens array on a polymer substrate offers an attractive unclonable anticounterfeiting label design. A random pattern of bright emission points is created due to the random coincidences of light focused by a microlens with an underlying phosphor microparticle. The change of the bright point patter with the angle of the incident light (owing to a shift in the locations of the focal points) makes the labels unclonable. This work examines the authentication of such labels using a single smartphone. The smartphone flashlight provides illumination whereas the camera is used for detection (optical filters prevent capture of scattered source light). A 196-bit binary string is created from the captured images to identify which lenses in the 14 × 14 array create bright emission points for a given position of the smartphone. The classification of test and reference images as matching or not is achieved with >99% confidence, as is a 1 cm tolerance for the positioning accuracy of the smartphone. Moreover, authentication is possible for different distances between flash and camera provided this is less than 3 cm. In summary, the present work quantifies the good potential of the microlens array microphosphor unclonable label concept for authentication using a smartphone

Dermoscopy of Hair and Scalp Disorders (Trichoscopy) in Skin of Color—A Systematic Review by the International Dermoscopy Society “Imaging in Skin of Color” Task Force

Hair and scalp disorders are of significant interest for physicians dealing with dark phototypes due to their prevalence and potential aesthetic impact resulting from a higher tendency for scarring. In order to facilitate their non-invasive diagnosis, several dermoscopic studies have been published, yet data are sparse and no systematic analysis of the literature has been performed so far. This systematic literature review summarizes published data on trichoscopy of hair and scalp diseases (trichoscopic findings, used setting, pathological correlation, and level of evidence of studies). A total of 60 papers addressing 19 different disorders (eight non-cicatricial alopecias, nine cicatricial alopecias, and two hair shaft disorders) were assessed, for a total of 2636 instances. They included one cross-sectional analysis, 20 case-control studies, 25 case-series, and 14 single case-reports, so the level of evidence was V and IV in 65% and 33% of cases, respectively, with only one study showing a level of evidence of III. Notably, although there is a considerable body of literature on trichoscopy of hair/scalp diseases, our review underlined that potentially significant variables (e.g., disease stage or hair texture) are often not taken into account in published analyses, with possible biases on trichoscopic patterns, especially when it comes to hair shaft changes. Further analyses considering all such issues are therefore needed

Dermoscopy of Infectious Dermatoses (Infectiouscopy) in Skin of Color—A Systematic Review by the International Dermoscopy Society “Imaging in Skin of Color” Task Force

Dermoscopy has been showed to facilitate the non-invasive recognition of several infectious disorders (infectiouscopy) thanks to the detection of peculiar clues. Although most of the knowledge on this topic comes from studies involving light-skinned patients, there is growing evidence about its use also in dark phototypes. This systematic literature review summarizes published data on dermoscopy of parasitic, bacterial, viral and fungal dermatoses (dermoscopic findings, used setting, pathological correlation, and level of evidence of studies) and provides a homogeneous terminology of reported dermoscopic features according to a standardized methodology. A total of 66 papers addressing 41 different dermatoses (14 bacterial, 5 viral, 11 fungal infections, and 11 parasitoses/bites and stings) and involving a total of 1096 instances were included in the analysis. The majority of them displayed a level of evidence of V (44 single case reports and 21 case series), with only 1 study showing a level of evidence of IV (case-control analysis). Moreover, our analysis also highlighted a high variability in the terminology used in the retrieved studies. Thus, although promising, further studies designed according to a systematic and standardized approach are needed for better characterization of dermoscopy of infectious skin infections