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The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of data that can be obtained from an individual sample and renders it difficult to produce statistically relevant data for unique and rare materials. Resonant cavity dielectric spectroscopy is a non-destructive, contactless technique which can simultaneously interrogate both sides of a sheeted material and provide measurements which are suitable for statistical interpretations. This offers analysts the ability to quickly discriminate between sheeted materials based on composition and storage history. In this methodology article, we demonstrate how contactless resonant cavity dielectric spectroscopy may be used to differentiate between paper analytes of varying fiber species compositions, to determine the relative age of the paper, and to detect and quantify the amount of post-consumer waste (PCW) recycled fiber content in manufactured office paper.

The reactivity of N-cyanomethyl quaternary salts of 4-, 5- and 7-azaindoles towards salicylic aldehydes has been studied. The interaction of azaindolium salts with salicylic aldehydes proceeds as a base-promoted domino reaction, giving the corresponding chromenoimidazopyrrolopyridines. In the case of the 7-(cyanomethyl)-7-azaindolium salt, the reaction was found to be more sensitive, but the use of the 1-methyl-substituted salt allowed the synthesis of the desired compounds, incorporating the heterocyclic core of isogranulatimide C, a marine natural product.

Per- and polyfluoroalkyl substances are synthetic environmental pollutants previously used for packaging applications as a grease, oil, and water-resistant coating. Exposure reported in previous studies highlighting potential concerns with public health. This study evaluated performance of coated paper packaging used for microwave popcorn, snacks, and sandwich bags for presence of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Current paper packaging materials: seven popcorn bags and three snack and sandwich bags were analysed for PFOA and PFOS and compared to concentrations in microwave popcorn bags between 2005 and 2018. Only two microwave popcorn bags had average PFOA content above the limit of quantitation of 5.11 ng g

Metamaterial has become a hotspot in many research fields, including electromagnetism, thermodynamics and mechanics, as it can offers additional design freedom for material to obtain novel properties. Especially for the electromagnetic devices, various interesting electromagnetic properties which cannot be found in nature materials can be realized, such as negative refraction, invisible cloak, etc. Herein, we provide an overview of paper-based metamaterial for microwave application. This work reviews the metamaterial realized on paper substrate, including the fabrication techniques, application fields, as well as the outlook on future directions of the paper-based metamaterial for the readership.

Simultaneously ultrasonic wave and microwave assisted technique (SUMAT), as a method of process intensification, was first applied to the preparation of nanocellulose whiskers (NCWs) from filter paper by sulfuric acid hydrolysis. The effects of temperature, sulfuric acid concentration, and mass of raw material and time on the yield of NCWs were investigated by single-factor experiments, and the preparation conditions were optimized with response surface methodology. The obtained NCWs were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and thermal gravimetry. The results showed NCWs were facilely prepared by using SUMAT. However, some harsh reaction conditions such as high temperature, strong acidity and long time treatment easily induced the reduction of the yield of NCWs. Under the optimal conditions, the yield and the crystallinity of NCWs with the crystal form of cellulose Iα is 85.75% and 80%, respectively.

A major application of microfluidic paper-based analytical devices (mu PADs) includes the field of point-of-care (POC) diagnostics. It is important for POC diagnostics to possess properties such as ease-of-use and low cost. However, mu PADs need multiple instruments and fabrication steps. In this study, two different chemicals (Hexamethyldisilazane and Tetra-ethylorthosilicate) were used, and three different methods (heating, plasma treatment, and microwave irradiation) were compared to develop mu PADs. Additionally, an inkjet-printing technique was used for generating a hydrophilic channel and printing certain chemical agents on different regions of a modified filter paper. A rapid and effective fabrication method to develop mu PADs within 10 min Was introduced using an inkjet-printing technique in conjunction with a microwave irradiation method. Environmental scanning electron microscope (ESEM) and x-ray photoelectron spectroscopy (XPS) were used for morphology characterization and determining the surface chemical compositions of the modified filter paper, respectively. Contact angle measurements were used to fulfill the hydrophobicity of the treated filter paper. The highest contact angle value (141 degrees +/- 1) was obtained using the microwave irradiation method over a period of 7 min, when the filter paper was modified by TEOS. Furthermore, by using this method, the XPS results of TEOS-modified filter paper revealed Si2p (23%) and Si-O bounds (81.55%) indicating the presence of Si-O-Si bridges and Si(OEt) groups, respectively. The ESEM results revealed changes in the porous structures of the papers and decreases in the pore sizes. Washburn assay measurements tested the efficiency of the generated hydrophilic channels in which similar water penetration rates were observed in the TEOS-modified filter paper and unmodified (plain) filter paper. The validation of the developed mu PADs was performed by utilizing the rapid urease test as a model test system. The detection limit of the developed mu PADs was measured as 1 unit ml(-1) urease enzyme in detection zones within a period of 3 min. The study findings suggested that a combination of microwave irradiation with inkjet-printing technique could improve the fabrication method of mu PADs, enabling faster production of mu PADs that are easy to use and cost-effective with long shelf lives. (C) 2016 Elsevier B.V. All rights reserved.

The thermal development of latent fingerprints on paper surfaces is a simple, safe, and chemicals-free method, based on the faster heating of the substrate underlying the print residue. Microwave heating is proposed for the first time for the development of latent fingerprints on cellulose-based substrate, in order to add to the thermal development mechanism the further characteristic of being able to heat the fingerprint residues to a different extent with respect to the substrate, due to the intrinsic difference in their dielectric properties. Numerical simulation was performed to confirm and highlight the selectivity of microwaves, and preliminary experimental results point out the great potentialities of this technique, which allowed developing both latent sebaceous-rich and latent eccrine-rich fingerprints on different porous surfaces, in less than 30 sec time with an applied output power of 500 W. Microwaves demonstrated more effectiveness in the development of eccrine-rich residues, aged up to 12 weeks.

The usefulness of microwave muffle furnaces for increasing the efficiency of sulfated ash determination through automation was investigated. Substances critical in their behavior were selected as model substances for this purpose: megestrol acetate and a phthalazine derivative as substances with high foaming indices and azelaic acid as a substance with a high spatter index. The selection of an optimal temperature sequence in conjunction with quartz crucibles and/or with a spatter guard made of quartz filter paper made it possible to handle even these critical substances. The analysis results were comparable and reproducible in terms of classical pharmacopeia methodology.

Nach wie vor stellt die Leimdosierung wäßriger Leime an Sackbodenlegern für die Papiersackherstellung ein nicht befriedigend gelöstes technisches Problem dar. Die verbreitete manuelle Regelung der Leimdosierung durch den Maschinenführer resultiert oft in einer Überleimung der Sackböden mit negativen Folgen für die Festigkeit und die mikrobielle Stabilität der Säcke, bedingt durch den hohen Wassereintrag. Eine automatisch geregelte Dosierung des Leimauftrags setzt aber die Verfügbarkeit geeigneter, d. h. leistungsfähiger und preisgünstiger Sensortechnik voraus. Eines der Meßprinzipien, die für die Leimauftragsmessung wäßriger Leime in Frage kommen, ist die Mikrowellenabsorptionsmessung. Bereits verfügbare industrielle Mikrowellensensoren sind für den Einsatz am Sackbodenleger, bei dem eventuell bis zu 16 Meßstellen bestückt werden müssen, jedoch zu teuer. Seit einigen Jahren werden billige Mikrowellensender und -empfänger für Massenprodukte angeboten. Unter Verwendung dieser Komponenten könnte ein Leimauftragssensor zu sehr günstigen Kosten gebaut werden. Es wurde daher die Eignung dieser Mikrowellenkomponenten für die Leimauftragsmessung untersucht und ein Sensor-Prototyp für die Online-Messung des Leimauftrags am Sackbodenleger gebaut.

We explore the application of terahertz spectroscopic techniques for the remote determination of the water content of paper. The aim is the development of a rapid diagnostic imaging tool applicable in paper fabrication processes. THz radiation offers a high sensitivity for water, a good spatial resolution, and insensitivity to scattering at the paper surface. The advent of THz cameras makes fast large-area image detectors feasible. In this paper, we show for the case of a 0.6-THz fixed-frequency system, that the water content of paper can be determined with high accuracy. We demonstrate a quantitative (calibrated) method for determining the moisture content in paper based on extinction and phase measurements in the lower THz range with a spatial resolution in the mm-range and scanning times below two minutes.