Fentanyl and its analogues play a major role in the current opioid epidemic. In particular, these highly potent opioids have become a health hazard due to their use as additives in street drugs. ...Consequently, rapid on-site procedures for the analysis of this class of seized drugs are needed, especially considering the reported backlog of drug samples, which must undergo identification and confirmation tests to validate the presence of an illicit substance. Paper based devices are cheap sampling and analysis vehicles that have been shown capable of allowing rapid identification and confirmation of drugs of abuse. Modifying paper substrates by imprinting nanoparticles enables surface enhanced Raman spectroscopy (SERS) as well as a second analysis from the same substrate, namely paper spray ionization mass spectrometry. While such a procedure has been described for laboratory use, these illicit drug samples are typically collected in the field and this is where testing should be done. We combine paper SERS and paper spray MS on field-portable and commercial off-the-shelf (COTS) devices for the rapid and low-cost identification and confirmation of fentanyl and its analogues, enabling in situ analysis at the point of seizure of suspect samples. The commercial nature of both instruments moves this technology from the academic realm to a setting where the criminal justice system can realistically utilize it. The capabilities of this single-substrate dual-analyzer technique are further examined by sampling a variety of surfaces of forensic interest.
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Modification of calcium carbonate particles with surfactant significantly improves the properties of the calcium carbonate coating on paper. In this study, unmodified and CTAB ...(hexadecyltetramethylammonium bromide)- and oleate-modified calcium carbonate nanoparticles were prepared using the wet carbonation technique for paper coating. CTAB (cationic surfactant) and sodium oleate (anionic surfactant) were used to modify the size, morphology, and surface properties of the precipitated nanoparticles. The obtained particles were characterized using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, zeta potential measurements, thermal gravimetric analysis (TGA), and transmission electron microscopy (TEM). Coating colors were formulated from the prepared unmodified and modified calcium carbonates and examined by creating a thin coating layer on reference paper. The effect of calcium carbonate particle size and surface modification on paper properties, such as coating thickness, coating weight, surface roughness, air permeability, brightness, whiteness, opacity, and hydrophobicity, were investigated and compared with commercial ground (GCC) calcium carbonate-coated papers. The results show that the obtained calcium carbonate nanoparticles are in the calcite phase. The morphology of the prepared calcium carbonate nanoparticles is rhombohedral, and the average particle diameter is less than 100 nm. Compared to commercial GCC, the use of unmodified and CTAB- and oleate-modified calcium carbonate nanoparticles in paper coating improves the properties of paper. The highest measured paper properties were observed for paper coated with oleate-modifed nanoparticles, where an increase in smoothness (decrease in paper roughness) (+23%), brightness (+1.3%), whiteness (+2.8%), and opacity (+2.3%) and a decrease in air permeability (−26%) was obtained with 25% less coat weight. The water contact angle at a drop age time of 10 min was about 112° for the paper coated with oleate-modified nanoparticles and 42° for paper coated with CTAB-modified nanoparticles compared to 104° for GCC-coated paper.
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Purpose
The surface energy of the printing material can be increased to desired levels with different chemicals or methods. However, the important thing is that the surface properties of printing ...material are not affected negatively. In this way the aim of this paper provide that the surface properties of matte and glossy coated paper is improved by the argon containing atmospheric pressure plasma device because the plasma treatment method does not occur surface damaging on the papers.
Design/methodology/approach
In experimental studies, test samples cut from 160 mm × 30 mm in size from 115 g/m2 gloss- and matt-coated papers were used. The plasma treatments of paper samples were carried out with an argon containing atmospheric pressure plasma device of laboratory scale that produces plasma of the corona discharge type at radio frequency. The optimized plasma parameters were at a frequency of 20 kHz and plasma power 200 W. A copper electrode of length 12 cm and diameter 2.5 mm was placed in the centre of the nozzle.
Findings
Research findings showed that the surface energies of the papers increased with the increase in plasma application time. While the contact angle of the untreated glossy paper is 82.2, 8 second plasma applied G3 sample showed 54 contact angle value. Similarly, the contact angle of the base paper of matt coated is 91.1, while M3 is reduced to 60.4 contact angles by the increasing plasma time.
Originality/value
Plasma treatment has shown that no chemical coating is needed to increase the wettability of the paper surface by reducing the contact angle between the paper and the water droplet. In addition, the surface energies of all papers treated by argon gas containing atmospheric pressure plasma, increased. Plasma treatment provides to improve both the wettability of the paper and the adhesion property required for the ink, with an environmentally friendly approach.
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•Strategies for improving colorimetric performance of paper-based analytical devices.•Review of color quality enhancement techniques based on printing principles.•First proposing the ...selectivity of paper assaying environment for a reaction.•Review of Image processing methods towards detection sensitivity improvement.•Designs that enhance the portability of colorimetric PADs for field use.
Colorimetric paper-based analytical devices (PADs) have been widely fabricated due to the ease of construction of colorimetric reactions on paper and the high compatibility with low-cost and easy-to-use imaging devices for on-site analysis and results recording. However, the further advance of colorimetric PADs is limited by the detection sensitivity and other intrinsic limitations of paper regarding the color quality. This review summarizes the strategies for improving the colorimetric performances (color intensity and uniformity) of PADs. In particular, the principles of controlling liquid-paper interaction for the color intensity enhancement, developed in printing research, are discussed in relation to PAD designs. The influence of the paper assaying environment to the paper assaying selectivity is discussed through a case study for the first time. Image capture techniques and image process algorithms are related to the accuracy and sensitivity of the colored results, which are carefully introduced. Finally, based on the tendency of improvement of colorimetric PADs for practical applications, we summarized the designs that enhance the portability of colorimetric PADs. It is believed that the new links and opinions provided in this review may be useful to researchers to address the challenges in designing future colorimetric PADs with improved sensitivities for field use.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We present a laboratory experiment, developed around a pair of instrumental analysis techniques, Raman spectroscopy and ambient ionization mass spectrometry (MS), conducted by senior chemistry ...undergraduate students for bulk analysis of over-the-counter drugs using benchtop versions of the two instruments, as well as trace analysis of illicit drugs utilizing the corresponding portable instruments. The identification and confirmation of seized drugs is a routine operation in forensic laboratories that can be simplified using these two instrumental techniques in tandem. Bulk samples are readily analyzed using conventional Raman spectroscopy followed by paper cone spray ionization (PCSI) MS, while trace analysis is allowed by a simple single-substrate dual-analyzer method using surface enhanced Raman spectroscopy (SERS) from paper followed by paper spray ionization (PSI) MS. The introduction of these novel strategies to the students exposed them to potential career paths in forensic science by means of a hands-on experience that provided fundamental knowledge about this set of analytical methods, including intercomparisons of their performance, as well as practical issues like costs, regulations and databases. The use of portable instrumentation represents an additional learning experience for the students, considering that it is cutting-edge technology that is just now being transferred from academic to industrial labs and that it allows a valuable discussion of the advantages and disadvantages of bringing the laboratory to the field.
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•Trace forensic analysis by pSERS followed by PSI-MS.•Bulk forensic analysis by Raman spectroscopy followed by PCSI-MS.•Rapid drug analysis by two complementary analytical techniques.•Forensic identification and confirmation.•Analytical laboratory exercise for undergraduates connecting to forensic analyses.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•WPU surface sizing agents are synthesized with IPDI, PCL, DMPA and EDA.•Viscosity increases as NCO/OH molar ratio or DMPA content increases.•Particle size increases with NCO/OH molar ...ratio but decreases with DMPA content.•WPU emulsions show different properties as the chemicals-adding sequence varies.•The sized papers have much better physical properties than the unsized ones.
In this work, a two-step synthesis methodology has been used to synthesize a series of waterborne polyurethane (WPU) emulsions with isophorone diisocyanate (IPDI), poly-caprolactone diol (PCL) and dimethylol propionic acid (DMPA) as monomers and ethylenediamine (EDA) as the chain extender, respectively. The influences of the NCO/OH molar ratio, DMPA content, chemicals-adding sequence, and acetone content on the physical properties of the resultant emulsions have been investigated in detail. The results show that the emulsion viscosity increases with an increase in the NCO/OH molar ratio or DMPA content whereas it declines sharply as the acetone amount increases. The emulsion particle size is seen to increase with the NCO/OH molar ratio but it decreases as the DMPA content increases. The chemicals-adding sequence is observed to strongly affect the particle size and viscosity of the resultant emulsions. For cast films, with an increase in the NCO/OH molar ratio, the elongation monotonically decreases while the tensile strength is seen to increase at first and then deceases. The film water absorption capacity is found to go up as the DMPA content increases. Furthermore, after sized with the emulsions, the paper water resistance is markedly improved and the 30s Cobb value is seen to decrease by 63% as compared to the unsized counterpart. The paper folding resistance and the tensile index are also improved to certain extents. For producing well-performed WPU emulsions for sizing paper sheets, an NCO/OH molar ratio of 1.6–1.8 and a DMPA content of 6.0–7.0wt.% are preferably chosen.
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•WPU emulsions as surface sizing agents are synthesized with TDI and IPDI.•Particle size increases as the NCO/OH and TDI/IPDI molar ratio increase.•Viscosity increases as the NCO/OH molar ratio and ...DMPA content increase.•Water resistance increases as the NCO/OH and TDI/IPDI molar ratio increase.•The sized papers have much better mechanical properties than the unsized ones.
Waterborne polyurethane (WPU), used as surface-sizing agents, has received increasing concerns in the papermaking industry. In this work, using two-step synthesis techniques of pre-polymerization and chain-extending reaction, a series of new self-emulsifying WPUs have been obtained with toluene diisocyanates (TDI) and isophorone diisocyanate (IPDI) as the monomers, dimethylol-propionic acid (DMPA) as hydrophilic chain extender. The influences of the NCO/OH molar ratio, DMPA contents, and TDI/IPDI molar ratio on the physical properties of the resultant emulsions have been investigated in detail using various characterization methods. Furthermore, the emulsions synthesized have been used for paper surface sizing applications. After sized, the paper water resistance along with other properties has been improved greatly as compared with the unsized counterparts. In view of the paper sizing effect, well-performed WPUs may be synthesized with NCO/OH molar ratio of 1.6–1.8, DMPA of 5.0–7.0% and TDI/IPDI molar ratio of 5:1.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Paper surfaces under the microscopic view are observed to be formed by intertwisted wood fibers. Such structures of paper surfaces are unique from one location to another and are almost impossible to ...duplicate. Previous work used microscopic surface normals to characterize such intrinsic structures as a "fingerprint" of paper for security and forensic applications. In this work, we examine several key research questions of feature extraction in both scientific and engineering aspects to facilitate the deployment of paper surface-based authentication when flatbed scanners are used as the acquisition device. We analytically show that, under the unique optical setup of flatbed scanners, the specular reflection does not play a role in norm map estimation. We verify, using a larger dataset than prior work, that the scanner-acquired norm maps, although blurred, are consistent with those measured by confocal microscopes. We confirm that, when choosing an authentication feature, high spatial-frequency subbands of the heightmap are more powerful than the norm map. Finally, we show that it is possible to empirically calculate the physical dimensions of the paper patch needed to achieve a certain authentication performance in equal error rate (EER). We analytically show that log(EER) is decreasing linearly in the edge length of a paper patch.
We present a laboratory experiment, developed around a pair of instrumental analysis techniques, Raman spectroscopy and ambient ionization mass spectrometry (MS), conducted by senior chemistry ...undergraduate students for bulk analysis of over-the-counter drugs using benchtop versions of the two instruments, as well as trace analysis of illicit drugs utilizing the corresponding portable instruments. The identification and confirmation of seized drugs is a routine operation in forensic laboratories that can be simplified using these two instrumental techniques in tandem. Bulk samples are readily analyzed using conventional Raman spectroscopy followed by paper cone spray ionization (PCSI) MS, while trace analysis is allowed by a simple single-substrate dual-analyzer method using surface enhanced Raman spectroscopy (SERS) from paper followed by paper spray ionization (PSI) MS. The introduction of these novel strategies to the students exposed them to potential career paths in forensic science by means of a hands-on experience that provided fundamental knowledge about this set of analytical methods, including intercomparisons of their performance, as well as practical issues like costs, regulations and databases. The use of portable instrumentation represents an additional learning experience for the students, considering that it is cutting-edge technology that is just now being transferred from academic to industrial labs and that it allows a valuable discussion of the advantages and disadvantages of bringing the laboratory to the field.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The anti-counterfeiting is an ongoing problem whose solution requires significant human and financial resources. Eventual additional expenses are reflected in the final price of a protected product ...that means the customers pay for anti-counterfeiting. Simple and inexpensive method for document authenticity verification development and implementation, aimed to discourage documents counterfeiting in general and as a consequence guarantee authenticity of accompanying documents, bring the customer confidence in a product quality, reducing the product price. The article represents a novel method of paper document validation using modern smartphones. The proposed paper document validation method is based on paper surface structure comparison of the registered reference document and the candidate document under validation. The method allows regular owner of a smartphone to quickly validate the paper document without having any knowledge about the validation process itself. The proposed solution is characterized by high availability and scalability, which are dictated by wide popularity of smartphones and high demand for tools from this category. To achieve stable and effective work of such system the special technical design approach is required. The usage of microservice based approach for system design and implementation allows to solve mentioned problem and to allocate the hardware resources efficiently to make the system work under high load stable.
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