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The Special Issue, entitled “Feature Papers in Food Chemistry”, is a collection of important high-quality papers (original research articles or comprehensive review papers) published in open access format [...]

Paper spray (PS) is a simple and innovative ambient ionization technique for mass spectrometry (MS) analysis. Under PS-MS conditions, chemical reactions, which usually occur slowly on a bulk scale, are accelerated. Moreover, the formation of products and transient species can be easily monitored. In this manuscript, reactions between phthalic anhydride and diamines were conducted and monitored using a PS-MS platform. The reaction products (phthalimides) have many pharmaceutical applications, but their traditional syntheses can take hours under reflux, requiring laborious purification steps.In situ reactions were performed by dropping methanolic solutions of phthalic anhydride and diamines on a triangular paper. The analyses were achieved by positioning the triangle tip in front of the mass spectrometer entrance, whereas a metal clip was attached to the triangle base. After adding methanol to the paper, a high voltage was applied across the metal clip, and the mass spectra were acquired.The intrinsic reactivity of alkyl and aromatic diamines was evaluated. The carbon chain remarkably influenced the reactivity of aliphatic diamines. For aryl diamines, the ortho isomer was the most reactive. Moreover, for aryl amines with electron-withdrawing substituents, no reaction was noticed.Taking advantage of the unique characteristics of PS-MS, it was possible to investigate the intrinsic reactivity of model alkyl (ethylene versus propylene) and aryl (o-phenylene versus m-phenylene and p-phenylene) diamines towards phthalic anhydride. Some crucial parameters that affect the intrinsic reactivity of organic molecules, such as isomerism, intramolecular interaction, and conformation, were easily explored.

Development of a foam-formed cellulose filter paper with high wet strength was carried out for application as a drinking water filter. The wet strength and antimicrobial activity of cellulose foam paper against several bacteria species (Bacillus subtilis MTCC 441 (Gram +ve), B. cereus NCDC 240 (Gram +ve), Pseudomonas aeruginosa NCDC 105 (Gram -ve), Klebsiella pneumonia NCDC 138 (Gram -ve), and Escherichia coli MTCC 40 (Gram -ve)) were investigated. The morphology and structure of the cellulose foam paper were characterized using scanning electron microscopy (SEM). The results of our study confirmed that glutaraldehyde solution or 1,2,3,4-butanetetracarboxylic acid (BTCA) added to cellulose foam paper pretreated with cationic polyacrylamide (C-PAM) provided very high and stable wet strength performance together with excellent antimicrobial properties.

Bisphenol A (BPA) was commonly used as color developer for thermal paper such as cash register receipts, labels or tickets. Therefore, thermal paper was considered by the European Food Safety Authority (EFSA) as the main source of human exposure to BPA beside epoxy based food contact materials. In this study, a German market analysis on the use of BPA and alternative color developers in thermal paper receipts is provided for the years 2015, 2016 and 2017.114 (2015), 98 (2016) and 99 (2017) samples were randomly collected and analyzed by HPLC-DAD. In summary, BPA was still the most frequently found color developer (48.2% in 2015, 46.9% in 2016 and 52.5% in 2017). The most commonly used alternative was the phenol-free substance Pergafast® 201 (34.2%, 33.7%, 40.4%). The bisphenol analogs bisphenol S (BPS; 11.4%, 9.2%, 6.1%) and D8 (6.1%, 7.1%, 1.0%) were less common. Another phenol-free substituent, a urea urethane compound (UU), was also detected (3.1% in 2016). Concentrations of color developers in thermal paper ranged from 1.4 to 32.4 mg/g (median values between 2.5 and 15.9 mg/g). Concentrations of BPA were found to be highest followed by BPS, UU, Pergafast® 201 and D8. In addition, two pharmacologically active substances, dapsone (6.0 mg/g) and tolbutamide (5.5 mg/g), were detected in a non-marketed thermal paper, that was supposed to use ascorbic acid as initial color developer. Different release experiments of the detected color developers were performed. Sensitizers 1,2-diphenoxy-ethane, 1-phenylmethoxy-naphthalene and diphenylsulfone, used frequently in the thermal paper processes, were quantified.

The unique features of cellulosic paper including flexibility, biodegradability, and low cost enables it as a versatile, sustainable biomaterial for promising applications. In the paper industry, microsized mineral particles are widely used in the production of printing/writing paper grades, while rosin derived from trees is the earliest internal sizing agent for paper hydrophobication. On the basis of existing commercial practices associated with the use of mineral particles and rosin in paper production, we present a process concept of converting cellulosic fibers (paper-grade pulp) into "sticky" superhydrophobic paper involving the use of microsized mineral particles and rosin (a tree-derived natural product, mainly a mixture of resin acids, especially abietic acid with chemical formula of C19H29COOH). Internal filling of cellulosic networks with mineral particles was basically used to hold out the mineral particles added at the surface, and the delicate integration of wet-end/surface applications of mineral particles with paper surface engineering with rosin/alum led to the development of "sticky" superhydrophobicity, i.e., ultrahigh water-repellency and strong adhesion to water. This proposed concept may provide valuable implications for expanding the use of paper-based products to unconventional applications, e.g., ultrahigh-performance ink jet printing paper for mitigating the "coffee-ring effect" and paper-based microfluidic devices for biomedical testing.

The growing trend in biodegradable and renewable materials has generated a demand for new food packaging applications. This study aimed to produce active cellulose-based papers incorporated with two different essential oil isolated active compounds, eugenol, and linalool, to promote the inhibition of pathogenic bacteria's growth. Cellulose was extracted from eucalyptus sawdust by receiving chemical and mechanical treatment and incorporating the active compounds by microwave. FTIR, SEM, TGA, DSC, and antibacterial activity against E. coli, Salmonella, S. aureus, and L. monocytogenes characterized active papers prepared by casting. Cellulose–eugenol papers showed chemical interactions by hydrogen bonding, in concern to linalool paper bands, identified by FTIR results. Highlighting that after the active compound's addition, the hydrogen energy bond values decreased from 22.5 to 22.3 kJ mol−1, confirming the cellulose fibers' swelling with the oils, which slightly amorphized the papers. The active compounds changed the paper's morphology, increasing porosity and roughness, as seen in the SEM images. Besides, TGA indicated that the active compounds increased the papers' thermal resistance. The active papers exhibited excellent antimicrobial activity against all the microorganisms; the cellulose–eugenol papers demonstrated a more significant antibacterial effect (24 mm), with a larger inhibition zone than linalool paper (12 mm). These results revealed that cellulose-based papers containing eugenol or linalool have good potential to prepare antimicrobial edible papers or coatings for various types of food packaging applications.

"In this study, reference papers prepared in accordance with the INGEDE 11p standard (International Association of the Deinking Industry) were recycled three times. Initially, reference papers were subjected to wetting, pulping, storage, deinking, dispersing and bleaching processes. At the end of these processes, test papers were produced and their optical characteristics were examined. The brightness value of writing papers (of 80 grams) was determined to be of 86%, following the TS 11610:2017 standard. In order to bring the brightness of the produced laboratory test papers to the specified value, double-stage bleaching was applied: with 0.4% FAS in the first stage and H2O2 in the second stage. The physical and optical properties of the test papers that reached the standard brightness value were determined. Overall, the final products were recycled three times. At the end of the third recycling stage, changes in paper fibers were examined. As a result, it was observed that the breaking, tear and burst resistance of the obtained papers gradually decreased at the end of each recycling stage. In addition, because of the narrowing fiber surface, it was determined that the opacity value of the paper decreased at the end of each recycling stage. According to the fiber classification results, the fiber size shrank at the end of the third recycling stage and a large part of the fibers remained in the 200 mesh. Paper fibers are recycled 3.6 times in Europe. This rate is approximately 2.4 times higher than the world average. This study offers interesting results regarding cellulose recycling, which has gained great importance in recent years. "

A sensitive, rapid and efficient ionic liquid-based vortex assisted liquid-liquid microextraction (IL-VALLME) with Liquid Chromatography Mass spectrometry (LC-MS/MS) method is proposed for the determination of bisphenols in thermal paper. Extraction factors were systematically optimized by response surface methodology. Experimental factors showing significant effects on the analytical responses were evaluated using design of experiment. The limit of detection for Bisphenol-A (BPA) and Bisphenol-S (BPS) in thermal paper were 1.25 and 0.93μgkg-1 respectively. The dynamic linearity range for BPA was between 4 and 100μgkg-1 and the determination of coefficient (R2) was 0.996. The values of the same parameters were 3-100μgkg-1 and 0.998 for BPS. The extraction recoveries of BPA and BPS in thermal paper were 101% and 99%. Percent relative standard deviation (% RSD) for matrix effect and matrix match effects were not more than 10%, for both bisphenols. The proposed method uses a statistical approach for the analysis of bisphenols in environmental samples, and is easy, rapid, requires minimum organic solvents and efficient.

The occurrence of mineral oil hydrocarbons (MOH) in cellulose-based packaging is mainly due to the offset printing process where MOH are used as a ink pigments' solvent. The MOH migration from paper/paperboard to food is matter of concern for EFSA, members state authorities, consumers, and food industry. In this study, the feasibility to stabilize MOH by adding a sorbent into recycled paper obtained through a common washing process was investigated and the migration to wheat flour/Tenax® assessed. Among several white/pale yellow porous materials, organo-modified powder silica MCM-41-Si(CH3)3 showed the best combination between affinity for MOH (184% dw) and stability to thermal regeneration. A freshly issued newspaper with >3000 mg MOH kg-1 was used to produce recycled paper at a laboratory-scale plant. MCM-41-Si(CH3)3 was added at the pulping step (1% dw) and the sorbent-enriched pulp handled according to a washing paper production process with no effect on the paper optical brightness. The MOH content of the wheat flour in contact with the sorbent-enriched paper under accelerated migration conditions (15 days at 40 °C) resulted 20% of that contacted with control paper (4.3 ± 1.1 and 20.4 ± 5.5 mg kg-1, respectively), despite its contamination was 24% higher than the control. On the contrary, Tenax® contamination resulted 56.0 ± 10.0 and 47 ± 14.0 mg kg-1 when exposed to sorbent-enriched and control paper, respectively.

Waste paper is a major contributor to municipal and industrial waste, and its recycle and reuse are a current challenge. The aim of this research is to convert waste paper into value-added cellulose films through rapid dissolution in pre-cooled H2SO4 aqueous solution. Two types of waste paper, office paper and cardboard, could be dissolved within 210 s. The regenerated office paper films were transparent, and exhibited excellent mechanical properties (tensile strength: 77.55 ± 6.52 MPa, elongation at break: 2.67 ± 0.30 %, and Young’s modulus: 5451.67 ± 705.23 MPa), which were comparable to those of cellulose films prepared from spruce pulp in the same solvent. The mixed paper films showed a dramatically reduced UV transmittance due to the existence of lignin. Moreover, the regenerated films were a promising matrix to load antimicrobial compounds, and thus inhibited the growth of pathogenic bacteria. Therefore, this work provides a convenient way to directly convert waste paper into biodegradable antimicrobial packaging materials.

Interest in water treatment by electrochemical methods has grown in recent years. Electrochemical oxidation has been applied particularly successfully to degrade different organic pollutants and disinfect drinking water. This study summarizes the effectiveness of the electrochemical oxidation technique in inactivating different primary biofilm forming paper mill bacteria as well as sulfide and organic material in pulp and paper mill wastewater in laboratory-scale batch experiments. Three different electrodes, boron-doped diamond (BDD), mixed metal oxide (MMO), and PbO2, were employed as anodes. The impact on inactivation efficiency of parameters such as current density and initial pH or chloride concentration of synthetic paper machine water was studied. The electrochemical behavior of the electrodes was investigated by cyclic voltammetry with MMO, BDD, and PbO2 electrodes in synthetic paper mill water as also with MMO and stainless steel electrodes with biocides. Some suggestions on the formation of different oxidants and oxidation mechanisms were also presented during the treatment. Aerobic paper mill bacteria species (Deinococcus geothermalis, Pseudoxanthomonas taiwanensis, and Meiothermus silvanus) were inactivated effectively (>2 log) at MMO electrodes by current density of 50 mA/cm2 and the time taken was 3 min. Increasing current density and initial chloride concentration of paper mill water increased the inactivation rate of D. geothermalis. The inactivation order of different bacteria species was M. silvanus > P. taiwanensis > D. geothermalis. It was observed that inactivation was mainly due to the electrochemically generated chlorine/hypochlorite from chloride present in the water and also residual disinfection by chlorine/hypochlorite occurred. In real paper mill effluent treatment, sulfide oxidation was effective with all the different initial concentrations (almost 100% reduction, current density 42.9 mA/cm2) and also anaerobic bacteria inactivation was observed (almost 90% reduction by chloride concentration of 164 mg/L and current density of 42.9 mA/cm2 in 5 min). Organic material removal was not as effective when comparing with other tested techniques, probably due to the relatively low treatment times. Cyclic voltammograms in synthetic paper mill water with stainless steel electrode showed that H2O2 could be degraded to radicals during the cathodic runs. This emphasizes strong potential of combined electrochemical treatment with this biocide in bacteria inactivation in paper mill environments. The results of the experiments showed that electrochemical oxidation could be used in paper mill waters for planktonic bacteria removal. Applying this technique together with some biocides can enhance the oxidation process, keeping the paper mill pipelines clean of slime formed by bacteria. Electrochemical oxidation is also a promising preliminary or tertiary treatment process in pulp and paper mill wastewater treatment, especially against refractory organic compounds which cannot be removed by biological processes.

RATIONALE Accurate measurement of trace compounds in blood samples is important in clinical diagnosis and life science. Ambient ionization mass spectrometry, however, suffers from the matrix effect when dealing with complex samples such as blood. Therefore, it is important to reduce the matrix effects in blood samples. METHODS A low-cost and disposable Teflon tube was used as a platform to precipitate the protein in blood. The analytes are extracted into organic solvent, and the precipitated protein can be adsorbed by the chromatography paper inserted. Therefore, the Teflon tube after precipitation can be directly subjected to paper spray ionization mass spectrometry, achieving one-step analysis of blood. RESULTS High sensitivity and satisfactory stability were achieved for pharmaceuticals, acids, and endogenic metabolites in blood. The absolute signal intensities of characteristic product ions of the tested analytes were 8-20 times higher after protein precipitation than those obtained using paper spray. Detection limits and quantitative performance were evaluated for three drugs: carbamazepine, metformin, and tioconazole. In addition, the limits of detection and quantitation were improved 9-14- and 8-12-fold, respectively. CONCLUSIONS Protein precipitation coupled to paper spray with a tube and then to mass spectrometry was successfully achieved and applied in the one-step analysis of trace compounds in blood samples. The experimental results showed that this method was sensitive, stable, convenient, and economic for the direct analysis of blood.

Refining of cellulose pulp is a critical step in obtaining high quality paper characteristics, however, this process is slow and costly especially for refining longer conifer fibers which are the preferred source for high quality paper production and give the paper its strength. In this study, we have applied a novel rotation generator of hydrodynamic cavitation for refining conifer rich pulp samples. Our results show that the device is capable of generating intense shear forces and multiple zones of developed cavitation and is successful in increasing the drainage rate of high consistency pulp (3%). The paper produced by means of the obtained pulp has higher quality because of its higher tensile index (50.5 kN m kg−1) and burst index (3 kPa m2 g−1). These physical parameters were sufficient for newsprint paper and other paper/board quality manufacture. In addition, this laboratory scale rotation generator proved to be economically efficient in comparison to the routinely employed laboratory beaters. To our knowledge, this is the first example of using hydrodynamic cavitation for the refinement of softwood fiber pulp of standard industrial consistencies (3%).

Thermal papers (e.g. point of sale receipts, adhesive labels, tickets) significantly contribute to contamination of paper material cycles and the environment with substances of (eco-) toxicological concern. In particular, they contain color developers like endocrine disrupting bisphenols in typical concentrations of about 1–2 percent per weight (wt%). Bisphenol A (BPA) was used as the common color developer over the last decades, but it will be restricted for thermal paper application in the European Union to a limit of 0.02 wt% from 2020 onwards. Consequently, a variety of BPA substituents such as bisphenol S (BPS) and its derivatives gain importance in thermal paper application. In this study, a rapid, reliable and cost-effective method for identification and quantification of BPA, alternative color developers and related substances like sensitizers is presented based on HPLC separation coupled with diode array detection (DAD) and Corona charged aerosol detection (CAD). Quantification was performed with regard to the intended use of the substances in thermal papers. Besides traditional UV external calibration using reference standards, alternative quantification approaches, in particular UV chromophore concentration for BPS derivatives and CAD universal response technique for low-volatile color developers, were applied and compared in order to allow quantification without reference substances. A market analysis for intended used color developers and sensitizers was performed on thermal paper samples (n = 211) collected in Germany during 2018 and 2019. Pergafast 201 (in 41.7% of the samples) was the most common color developer with concentrations above 0.02 wt%, followed by BPA (36.0%), BPS (13.3%) and other BPS derivatives known as D8, D-90, BPS-MAE and TGSA, that are mainly present in adhesive labels. Sensitizers were determined in over 90% of the samples.

Herein, we developed a novel, cheap, fast and simple portable sensing platform based on the photoluminescence (PL) quenching effect of paper-incorporated bovine serum albumin protein stabilized gold nanoclusters (BSA-AuNCs) when interacting with Cu ions (Cu2+) from real water samples. First, we demonstrated the sensibility and specificity of the BSA-AuNCs-based sensor for the detection of Cu2+ in solution via PL quenching effect, using a portable fluorescence spectrometer, under 502 nm LED excitation. The limit of detection (LOD) was found to be as low as 0.83 µM. For improved portability and accessibility, the sensing performance of BSA-AuNCs was successfully combined with the unique properties of Whatman paper substrates in order to develop a portable and ready-to-use sensor for the detection of Cu2+ from real water samples. The obtained BSA-AuNCs incorporated paper-based sensing substrate was successfully used for naked-eye detection of Cu2+ levels from water, under UV light, based on the visual detection of PL quenching. We obtained a LOD of 5 µM which was confirmed even for 14 days aged paper sensing substrates. The as-prepared BSA-AuNCs-paper-based sensor was validated for the detection of Cu2+ in different real water samples through the visual examination of the PL quenching on the paper substrates under UV light illumination and relevantly dangerous levels for humans or subaquatic organisms were successfully identified. The newly prepared BSA-AuNCs-incorporated paper-based sensing platform is easy-to-use and presents great promise in the fast, selective, qualitative and semi-quantitative naked-eye detection of Cu2+ in real water samples.

Paper-based packaging generally has poor performances in the gas/oil barriers. This work reports a paper-based packaging material prepared via the modification of conventional papers with TEMPO-oxidized cellulose nanofibers (TOCN)/cationic guar gum (CGG) hydrogel film. Specifically, the hydrogel film modification was realized through a layer-by-layer deposition on paper. The hydrogel film modification significantly improved the mechanical and barrier properties of the paper. Specifically, the 4-layer hydrogel film modified paper showed a tensile strength of 34.03 MPa and a burst strength of 510 kPa, respectively. In contrast, the unmodified paper exhibited a tensile strength of 26.78 MPa and a bursting strength of 388 kPa. The packaging performance of this TOCN/CGG hydrogel film modified paper was demonstrated via the fresh mooncake packaging test. Such hydrogel film not only provided the oil resistance, but also maintained the mooncake's freshness. This material can serve as a green and sustainable food packaging.

Ambient ionization of glycans is simply and efficiently achieved by spraying from an alkali metal salt-impregnated paper surface. Monosaccharides, oligosaccharides and ring glycans easily form abundant alkali metal adduct ions, and give simple and clean high-quality mass spectra. The enhancement is specific for glycans, compared to a wide variety of non-glycan compounds present in a matrix. In addition, molecular weight of unknown glycans can be further identified based on the ion mass difference of various alkali metal adduct ions from a certain compound when using a mixed salt-impregnated paper containing five cation salts. Successful determination of glycans and glycoconjugates in plant extracts, honey, blood and urine demonstrates the practicability of this approach to complicated matrices, especially biological matrices.

Whatman® cellulosic filter paper was used as a substrate for the synthesis of two zeolitic imidazolate frameworks (ZIFs); ZIF-8 and ZIF-67 with and without 2,2,6,6-tetramethyl-1-piperidine oxoammonium salt (TEMPO)-oxidized cellulose nanofibril (TOCNF). All synthesis procedures take place at room temperature via a one-pot procedure. The synthesis steps were followed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transforms infrared (FT-IR). Data indicated the formation of metal oxide that converted to a pure phase of ZIFs after the addition of the organic linker i.e. 2-methyl imidazole (Hmim). The materials were characterized using XRD, FT-IR, SEM, energy dispersive X-ray (EDX), nitrogen adsorption-desorption isotherms, and X-ray photoelectron microscope (XPS). Data analysis confirms the synthesis of ZIFs into Whatman® filter paper. The materials were used for the reduction of pollutants such as 4-nitrophenol (4-NP) compound to 4-aminophenol (4-AP). The materials exhibit high potential for water treatment and may open new exploration for hybrid materials consisting of cellulose and ZIFs.

Imparting electro-conductivity to cellulosic paper may allow this conventional material to hold great promise for a wide range of applications. In this work, polyaniline/cellulose nanocrystal (PANI/CNC) composite was prepared via emulsion polymerization and subsequently used as a conductive and reinforcing pigment for paper coating fabrication. Initially, the microstructure and properties of the fabricated PANI/CNC composite were comprehensively characterized. Furthermore, the effect of the PANI/CNC composite on the properties of paper coatings and coated paper was systematically investigated. The results showed that the viscosity and viscoelasticity of paper coatings were increased as a function of the PANI/CNC composite addition. Meanwhile, the increased CNC ratio in PANI/CNC composite led to the decreased viscosity and viscoelasticity of paper coatings. Furthermore, surface coating application was found to impart desired electro-conductivity and enhanced mechanical properties to coated paper. Compared to the coated paper without PANI/CNC composite, the coated paper with 4 wt% CNC added PANI/CNC composite maintained an electro-conductivity of 4.0 S·m−1 and exhibited increases of 14.6%, 30.7% in tensile index and folding strength, respectively. In particular, the electro-conductivity and mechanical properties of coated paper were also enhanced with the increased ratio of CNC in PANI/CNC composite.

Lithium metal anodes (LMAs) with high energy density have recently captured increasing attention for development of next-generation batteries. However, practical viability of LMAs is hindered by the uncontrolled Li dendrite growth and infinite dimension change. Even though constructing 3D conductive skeleton has been regarded as a reliable strategy to prepare stable and low volume stress LMAs, engineering the renewable and lithiophilic conductive scaffold is still a challenge. Herein, a robust conductive scaffold derived from renewable cellulose paper, which is coated with reduced graphene oxide and decorated with lithiophilic Au nanoparticles, is engineered for LMAs. The graphene cellulose fibres with high surface area can reduce the local current density, while the well-dispersed Au nanoparticles can serve as lithiophilic nanoseeds to lower the nucleation overpotential of Li plating. The coupled relationship can guarantee uniform Li nucleation and unique spherical Li growth into 3D carbon matrix. Moreover, the natural cellulose paper possesses outstanding mechanical strength to tolerate the volume stress. In virtue of the modulated deposition behaviour and near-zero volume change, the hybrid LMAs can achieve reversible Li plating/stripping even at an ultrahigh current density of 10 mA cm-2 as evidenced by high Coulombic efficiency (97.2 % after 60 cycles) and ultralong lifespan (1000 cycles) together with ultralow overpotential (25 mV). Therefore, this strategy sheds light on a scalable approach to multiscale design versatile Li host, promising highly stable Li metal batteries to be feasible and practical.

Paper-like electrodes are emerging as a new category of advanced electrodes for flexible supercapacitors (SCs). Graphene, a promising two-dimensional material with high conductivity, can be easily processed into papers. Here, we report a rational design of flexible architecture with Co9 S8 nanotube arrays (NAs) grown onto graphene paper (GP) via a facile two-step hydrothermal method. When employed as flexible free-standing electrode for SCs, the proposed architectured Co9 S8 /GPs exhibits superior electrochemical performance with ultrahigh capacitance and outstanding rate capability (469 F g-1 at 10 A g-1 ). These results demonstrate that the new nanostructured Co9 S8 /GPs can be potentially applied in high performance flexible supercapacitors.

Starch and poly(vinyl alcohol) based barrier coatings for flexible packaging papers were studied. Both octenyl succinate modified and hydroxypropylated corn and potato starches were blended with regular and ethylene modified poly(vinyl alcohol) to increase the water vapor barrier properties and enhance the flexibility of the starch coatings, in order to accomplish superior barrier performance. Phase separation between starch and poly(vinyl alcohol) was studied in detail, both in the solution and in dry draw-down coatings on paper. The barrier performance of the coated paper was evaluated with respect to water vapor transmission rate. Conditions for the creation of a thin surface layer consisting of only one of the pure polymers were identified and discussed in terms of phase separation in solution migration of poly(vinyl alcohol) to the uppermost surface layer. The phase separation promoted low water vapor transmission rates also with a rather high fraction of starch in the coatings.

The papers have a porous structure which can be a suitable medium for the growth of bacteria. Therefore, in the sanitary papers, creation of a suitable antibacterial property is necessary. In this way, the plant extracts were prepared using solid–liquid extraction method from the Rosmarinus officinalis, Olea europaea, Mentha spicata and Punica granatum. Relatively, the total phenol and flavonoid contents were determined according to colorimetric method. Their antioxidant activity was evaluated using DPPH method. The extracts were sprayed on the surface of the handsheets, and then their antibacterial activity was investigated. The results showed that extracts from the P. granatum has the highest phenol (5.82%) and antioxidant activity (71.13%), while the extract from the R. officinalis had the highest flavonoid (4.23%) and antibacterial activity (90.43%). Hence, it can be concluded that these two extracts could be the suitable combinations to create desirable antibacterial properties in the manufacture of papers with sanitary purposes.

An extraction and determination method is shown for the analysis of dyes and solvents present in two types of ballpoint pen inks that are deposited onto paper. Ink extracts are analysed using a combination of gas chromatography with mass spectrometry (GC-MS), and high-pressure liquid chromatography with photodiode array detection (HPLC-DAD), within a single sample extraction procedure. Seventeen solvents and thirteen dyes contained in two Montblanc® inks (black and blue) were monitored for 45 months at monthly intervals, in order to determine variations in the concentrations of the compounds over time. We also studied the relative variations between different compounds and the generation of degradation products such as phenol. The concentration data obtained from these compounds during their exposure have been analysed and a multiple regression model is developed for each ink type that allows an estimate of the exposure time of the ink on paper with a maximum error of between 4 and 7 months.

Hypothesis Due to their highly retentive properties, innovative recently developed, semi-interpenetrated hydrogels made up of poly(vinyl pyrrolidone) (PVP) chains embedded in a poly(2-hydroxyethyl methacrylate) (p(HEMA)) network should be efficiently used as cleaning material for fragile and degraded paper artworks. In restoration practice, indeed the wet cleaning of these artworks is usually performed by immersion of paper in water, a procedure which may lead to several drawbacks, including paper fibers swelling and dissolution of water-soluble original components. Experiments This class of gels were yet presented in literature, but their interactions with paper materials and ability to be spiked with active enzymes (as cleaning agents), have not been analyzed. To establish the suitability of these hydrogels as paper cleaning materials, first, a rheological and microstructural characterization of the gels was performed. Moreover, diffusion of macromolecules inside gels was studied using fluorescence microscopy, to check if these innovative hydrogels can be used as carriers for hydrolytic enzymes. Indeed, pastes and glues are usually found in old paper artworks, and their removal is a very delicate operation that requires a selective action, which is granted by specific hydrolytic enzymes. At the same time, spectroscopic analyses on paper samples under investigation before and after cleaning treatment has been performed, thus assessing the capabilty of these gels as cleaning materials. Findings With the aim of demonstrating the versatility of these hydrogels, several case studies, i.e., the removal of grime and water-soluble cellulose degradation byproducts, the removal of animal glue and the removal of starch paste from real samples, are presented. Results obtained with these gels have been compared to those obtained by using another gel used for paper artworks cleaning, i.e., Gellan gel.

Thermally upgraded Kraft (TUK) "Insuldur®" papers prepared from the same batch process but with a different percentage of stabilizing additives (1.2, 2.6 and 4.4% of nitrogen) were studied under accelerated aging at 170 °C. The increment of stabilizing additives in paper with the consequent increment of nitrogen content slows down the rate of molecular chain scission of the cellulose and reduces the paper tensile strength loss rate. However, a progressive reduction in the enhancement of the paper life span by the increment of nitrogenous additives in paper was observed. The cellulose degradation methanol and ethanol markers were found to be reliable and accurate for tracking the aging of TUK papers even with the variation of nitrogen content in paper. A promising correlation between methanol concentration and the paper tensile index with different nitrogen content was determined. This correlation could be used as a basis for developing tools to assess power transformers residual life. FTIR-ATR analyses of dicyandiamide in aged papers showed a rapid reaction and decomposition of dicyandiamide in other compounds that slows down cellulose aging. The nitrogen content of aged paper, measured with the Dumas method, showed a slight variation during the study. This implies that the nitrogen compounds continue to be attached, presumably by polar forces to the paper. Thermogravimetric analysis (TGA) of new and aged Insuldur® paper samples showed that nitrogen additives improve the thermal stability of paper at high temperatures.

As traditional barriers are vulnerable to organic solvents or surfactants, a new fluoroalkyl-silica barrier with superior confining ability was developed for paper-based analytical devices (PADs). The as-prepared fluoroalkyl-silica barrier is able to contain surfactant solutions and pure organic solvents even alcohols. Based on the fluoroalkyl-silica barrier, PADs associated with condensing-enrichment effect were explored for Ni(II) assays involving ethanol and bacteria assays including sodium dodecyl sulfate (SDS) and chloroform. The exhibited work has the potential to significantly expand the applications of paper-based microfluidics or assays to include process/analysis involving organic solvents or surfactant solutions.

Seeds directly determine the survival and population size of woody plants, but the genetic basis of seed weight in woody plants remain poorly explored. To identify genetic variations and candidate genes responsible for seed weight in natural woody populations, we investigated the hundred-seed weight of 198 paper mulberry individuals from different areas. Our results showed that the hundred-seed weight of paper mulberry was significantly associated with the bioclimatic variables of sampling sites, which increased from south to north along the latitudinal-temperature gradient. Using 2,414,978 high-quality SNPs from re-sequencing data, the genome-wide association analysis of the hundred-seed weight was performed under three models, which identified 148, 19 and 12 associated genes, respectively. Among them, 25 candidate genes were directly hit by the significant SNPs, including the WRKY transcription factor, fatty acid desaturase, F-box protein, etc. Most importantly, we identified three crucial genetic variations in the coding regions of candidate genes (Bp02g2123, Bp01g3291 and Bp10g1642), and significant differences in the hundred-seed weight were detected among the individuals carrying different genotypes. Further analysis revealed that Bp02g2123 encoding a fatty acid desaturase (FAD) might be a key factor affecting the seed weight and local climate adaptation of woody plants. Furthermore, the genome-wide investigation and expression analysis of FAD genes were performed, and the results suggested that BpFADs widely expressed in various tissues and responded to multiple phytohormone and stress treatments. Overall, our study identifies valuable genetic variations and candidate genes, and provides a better understanding of the genetic basis of seed weight in woody plants.

Nanocelluloses, such as cellulose nanofibers and nanocrystals, are sustainable nanomaterials that are generally extracted from natural raw materials in a top-down manner. These nanomaterials and their assemblies are facilitating new applications of biopolymers. However, creating nanostructures from conventional cellulosic materials including paper and cloth remains challenging. Herein, we report an approach for bottom-up nanostructuring of conventional microfibrous cellulose materials via a molecular self-assembly strategy. As a precursor cellulose material, paper was allowed to swell with aqueous phosphoric acid for the partial dissolution and hydrolysis of cellulose while maintaining its microfibrous structure. The generated cello-oligosaccharides in a dissolved state started to self-assemble upon adding water as a coagulant, resulting in nanospike-like assemblies on the microfiber surfaces. The resultant nanospiked papers were found to serve as a precursor for synthesizing silver nanoparticle-cellulose composites with bactericidal activities. Our findings promote the development of cellulose-based functional materials with nanostructures designed via molecular self-assembly.

Rationale Paper spray mass spectrometry (PS-MS) was used to analyze and quantify ampicillin, a hydrophilic compound and frequently utilized antibiotic. Hydrophilic molecules are difficult to analyze via PS-MS due to their strong binding affinity to paper substrates and low ionization efficiency, among other reasons. Methods Solvent and paper parameters were optimized to increase the extraction of ampicillin from the paper substrate. After optimizing these key parameters, a Resolution IV 1/16 fractional factorial design with two center points was employed to screen eight different design parameters simultaneously. Results Pore size, sample volume, and solvent volume were the most significant factors affecting average peak area under the curve (AUC) and the signal-to-blank (S/B) ratio for the 1 μg/mL ampicillin calibrant. After optimizing the key parameters, a linear calibration curve with a range of 0.2 μg/mL to 100 μg/mL was generated (R2 = 0.98) and the limit of detection (LOD) and lower limit of quantification (LLOQ) were calculated to be 0.07 μg/mL and 0.25 μg/mL, respectively. Conclusions The statistical optimization procedure undertaken here increased the mass spectral signal intensity by more than a factor of 40. This statistical method of screening followed by optimization experiments proved faster and more efficient, and produced more drastic improvements than typical one-factor-at-a-time experiments.

Gold nanoparticles (AuNPs) were directly synthesized and anchored on lignocellulose fiber without an external immobilizing agent via a facile green approach using unbleached kraft (UBK) softwood pulp. The obtained AuNPs were confirmed by UV–vis diffuse reflectance spectroscopy, field-emission scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The antioxidant behavior of the as-prepared AuNP-UBK fiber nanocomposite was evaluated by free radical scavenging of 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH). The nanocomposite fiber exhibited greatly enhanced radical scavenging activity compared to that of the pure fiber. As a consequence, AuNP-UBK nanocomposite paper showed exceptional antioxidant performance with a radical scavenging rate of over 98%, which is attributed to the synergistic effects of adsorption by the fiber–fiber network and subsequent catalytic activity of the AuNPs. This research indicated that AuNP-UBK fiber nanocomposites could be a new candidate for antioxidant active packaging for use in food preservation.

A novel simple and readily synthesized turn-on fluorescent probe 4-(benzo[d]thiazol-2-yl)-1,3-phenylene bis(2-chloroacetate) (BPBC) for cysteine (Cys) was reported. This probe was designed based on an excited-state intramolecular proton transfer (ESIPT) dye: benzothiazole, and two chloroacetate groups present in benzothiazole as the reaction sites for Cys. It shows high selectivity and sensitivity for Cys over other amino acids including the similar structured homocysteine (Hcy) and glutathione (GSH). In addition, probe BPBC was successfully applied to bioimage intracellular Cys in living cells with low cytotoxicity. More importantly, a paper test strip system was developed with probe BPBC for Cys detection conveniently.

Myrciaria floribunda, also known as rumberry, is a tree native to the Brazilian Atlantic Forest, where its fruits have the potential for commercial use. This study evaluates the antioxidant potential, determines the phytochemical profile, and chemically characterizes the rumberry fruit. Accessions were sampled from the Rumberry Active Germplasm Bank of the Federal University of Alagoas, Brazil. Physical characteristics, chemical characteristics, and phenolic compound content were analyzed. Chemical profile characterization was carried out using PSMS. Accessions had an average weight of 0.86 g. Accession AC137 presented a higher pulp yield (1.12 g). AC132 and AC156 had larger fruits, AC137 showed greater firmness (5.93 N), and AC160 had a higher and total phenolic content ratio (279.01 ± 11.11). Orange-colored accessions scored higher in evaluated parameters, except for AC160 for phenolic content. Thirty-two compounds were identified on positive ionization mode and 42 compounds on negative ionization mode using PSMS. Flavonoids, followed by the derivatives of benzoic acid, sugars, and phenylpropanoids, were the most prominent. Myricitrin, quercitrin, and catechin stand out as flavonoids that have been reported in previous studies with antioxidant and antimicrobial properties, in addition to health and therapeutical benefits, demonstrating the potential of the rumberry fruit.

Anaerobic digestion (AD) of lignocellulosic materials is commonly limited by the hydrolysis step. Unlike unprocessed lignocellulosic materials, paper and paper board (PPB) are processed for their fabrication. Such modifications may affect their methane yields and methane production rates. Previous studies have investigated the correlation between lignin and biomethane yields of unprocessed lignocellulosic materials; nevertheless, there is limited knowledge regarding the relationship between the AD kinetic parameters and composition of PPB. This study evaluated correlations of methane yields and Monod and Gompertz kinetic parameters with structural carbohydrates, lignin, and ash concentration of five types of PPBs. All components were used as single and combined independent variables in linear regressions to predict methane yield, maximum specific methanogenic activity (SMAmax), saturation constant (Ks), and lag phase (λ). Additionally, microbial community profiles were obtained for each PPB assay. Results showed methane yields ranging from 69.2 ± 8.61 to 97.2 ± 2.29% of PPB substrates provided. The highest correlation coefficients were obtained for SMAmax as function of hemicellulose / (lignin + ash) (R2 = 0.86) and for λ as a function of lignin + cellulose (R2 = 0.85). All other parameters exhibited weaker correlations (R2 ≤ 0.77). Relative abundance analyses revealed no major changes in the community profile for each of the substrates evaluated. The overall findings of this study are 1) combinations of structural carbohydrates, lignin, and ash used as ratios of degradable to either non-degradable or slowly degradable fractions predict AD kinetic parameters of PPB materials better than single independent variables, and 2) other components added during their fabrication may also influence both methane yield and kinetic parameters. This article is protected by copyright. All rights reserved

International audience; Hemicellulose materials are arguably the second most abundant renewable component of lignocellulosic biomass after cellulose. They are relatively under-utilized hetero-polysaccharides present in lignocellulosic biomass. In this research an alkaline treatment was optimized for extraction of polymeric hemicellulose from fully bleached hardwood pulp (B-HWP) and partially delignified switchgrass (SWG). The hemicellulose extracted from B-HWP was relatively pure with zero percent lignin and 89.5% xylose content whereas the partially delignified SWG hemicellulose contained about 6-3% lignin and 72–82% xylose, depending on the NaOH concentration during extraction (3–17% NaOH solution). A maximum molecular weight of SWG hemicellulose of 64,300 g/mol was achieved for the 10% NaOH solution extraction, whereas the MW of B-HWP hemicellulose at 10% NaOH solution extraction was lower at 49,200 g/mol. We have demonstrated that the residual lignin in SWG hemicellulose lowered the system Tg and this might be utilized as a way to increase the applications of hemicellulose in high value biomaterials. Furthermore, the hemicellulose could be crosslinked with zirconium to develop a water resistant gel for coating or adhesive applications. Our results showed that the loading stress required to break an hemicellulose based adhesive connection between two paper surfaces was 0.89, 2.02, 2.75, 3.46, and 3.11 (MPa) for 2, 4, 6, 8 and 10% AZC samples, indicating that up to about 8% AZC crosslinker in the hemicellulose increases the adhesive behavior of the material.

The conversion of heavy oil fractions into lighter oil fractions is highly essential for meeting the growing demand for fuels in continuous depletion of oil reserves and for environmental remediation. We demonstrate an oil degradation approach where oil microdroplets are sprayed in air at room temperature onto untreated TiO2 nanoparticles-coated filter paper to which we apply an electrical potential. Two model polycyclic aromatic hydrocarbons as well as a crude oil sample show degradation on the microsecond time scale. Heterogeneous catalysis of a biphasic (organic/aqueous) reaction occurs at the interface of microdroplets and the charged TiO2 surface. The fragmentation yield is increased by cycling the process. The relative fragmentation yield of a model compound (rubrene) increased from 16.9% in the first cycle to 32.6% in the third cycle. This convenient and efficient method suggests possible future industrial applications.

Hybrid composites were prepared with jute fabric and un-shredded newspaper in polyester resin matrix. The experiment was designed 1:2 weights ratio jute and unshredded newspaper to have 42 (w/w)% fibre content hybrid composites and two different sequences jute/paper/jute and paper/jute/paper of waste newspaper and jute fabric arrangement. Reinforcing material is characterized by chemically, X-ray diffraction methods, Fourier transform infrared spectroscopy and tensile testing. The tensile, flexural and interlaminar shear strength and fracture surface morphology of composites were evaluated and compared. It was found that tensile and flexural properties of the hybrid composite are higher than that of pure paper-based composite but less than pure woven jute composite. The hybridization effect of woven jute fabric and layering pattern effect on mechanical properties of newspaper/woven jute fabric hybrid composites were studied. The test results of composites were analyzed by one-way ANOVA (α=0.05), it showed significant differences among the groups.

A novel red-emitting dye, PB-NH2, was synthesized by incorporation of an electron rich phenothiazine moiety to classical boranil dye. PB-NH2 displayed excellent photophysical properties, such as long emission wavelength, large Stokes shift, strong emission both in solution and in solid state. Based on this attractive platform, Probe 1, was constructed for selective detection of thiophenol. Notably, Probe 1 was ultrasensitive in response to thiophenol, and the corresponding detection limits for thiophenol in theoretical and in experimental were determined to be 1.4 and 10 nM, respectively. Significantly, Probe 1 showed great potential for practical applications, and the applications in real water samples, in serum, on filter paper strips and in living cells were successfully demonstrated.

In this work, the types of products and their proportions, the evolution characteristics of the functional groups and gases products, the pollutants emission of combustible solid waste (CSW), paper mill sludge (PMS) and their blends were investigated by Py-GC/MS and TG-FTIR. For the blends, the proportions of PMS were 10%, 30% and 50%. The percentage of pyrolysis products (acid, hydrocarbon, aldehyde, alcohol, benzene, furan, phenol, ester and ketone) was pointed out. Among these, the content of acid was the maximum. Blended with 10% PMS, the percentage of alcohol reached the greatest. Both single sample and blends could be divided into two decomposition phases. The residue mass of blends increased from 17.74% to 30.47% with the PMS ratio increased. OH, CH, CO, CO, SO2, NO, HCl, CO, CH4 and CO2 were the main functional groups and gases products surveyed from the FTIR spectrums during co-pyrolysis. Adding PMS into CSW could reduce the emission of the pollutants and the lowest yield of pollutants (SO2, NO, HCl, CO and CO2) would be obtained covered with 50% PMS.

The crystal structure of a new bisphenol S derivative, 3,3′-diallyl-4,4′-dihydroxydiphenyl sulfone was analyzed. This compound is used as colour developer in high-performance thermal paper, because of its high colour sensitivity and excellent image stability. In the crystalline phase, each molecule of this derivative is linked to four neighbouring molecules by O H⋯O S intermolecular hydrogen bonds. In order to understand the solid-state properties of the new derivative, its hydrogen bonding features were compared to those of the parent bisphenol S compound. The hydrogen bonding network of the new derivative forms two-dimensional square lattice sheets stacked along the b axis. This stacking arrangement, which is different from that of the unsubstituted compound, results in a lower number of hydrogen bonds per unit volume. This structural feature was considered to be correlated with the considerably lower melting point of the new derivative compared to that of the unsubstituted one. This property would result in a good coloration sensitivity of the new derivative when used as colour developer.

Maintaining the quality of their final paper-based food packaging products at a high and constant level is a key issue for food packaging manufacturers to meet the customer demands. In the present study, in order to analyze the present status of quality of paper-based food packages in India, the fiber furnishes of different common paper- and paperboard-based food packages were studied by the Graff “C” staining test and their fiber morphological properties – by MorFi analysis. The staining test results showed that all the samples contained fiber furnish made either by the chemical or by the mechanical pulping process. Tea bags, dry fruit boxes and egg trays were made of 4 different fiber components, while sugar sachets and juice boxes contained 3 fiber components. It was also observed that all the samples contained hardwood and softwood chemical fibers. MorFi analysis determined the morphological properties of the fibers, including the mean fiber length and width, coarseness, kink angle, kinked fibers %, curl % and fines elements % in total analyzed fibers. The results thus obtained confirmed that both these techniques are very reliable and feasible tools to study the quality of paper-based food packages.

"Printability is a combination of paper-related factors that contribute to achieving the desired print quality level and relates to the paper's ability to absorb ink. An important property of ink on paper is its setting behavior. The spread and placement of the ink on the paper surface is affected by the surface structure of the paper. The surface topography of the paper is decisive in the process of ink placement on the paper surface. In this study, the effects of surface roughness of the paper on wettability, print gloss, ink color change and light fastness change were investigated. For this purpose, prints on papers with different surface roughness were made in accordance with ISO 12647-2 with Cyan color ink in accordance with DIN ISO 2846-1. The CIE L*a*b* and gloss values of the test prints, which were allowed to dry in order to detect color and print gloss differences on the paper surfaces, were measured periodically until the ink film was completely dry. In addition, the effects of the paper surface on the light fastness of the ink were measured and recorded. The results were discussed in terms of print quality. "

Imprecise control of fluid flows in paper-based devices is a major challenge in pushing the innovations in this area towards societal implementation. Assays on paper tend to have low reaction yield and reproducibility issues that lead to poor sensitivity and detection limits. Understanding and addressing these issues is key to improving the performance of paper-based devices. In this work, we use colorimetric analysis to observe the mixing behaviour of molecules from two parallel flow streams in unobstructed (on unpatterned paper) and constricted flow (through the gap of a patterned hourglass structure). The model system used for characterization of mixing involved the reaction of Fe3+ with SCN− to form the coloured, soluble complex Fe(SCN)2+. At all tested concentrations (equal concentrations of 50.0 mM, 25.0 mM or 12.5 mM for KSCN and FeCl3 in each experiment), the reaction yield increases (higher colorimetric signal) and better mixing is obtained (lower relative standard deviation) as the gap of the flow constriction becomes smaller (4.69–0.32 mm). This indicates enhanced passive mixing of reagents. A transition window of gap widths exhibiting no mixing enhancement (about 2 mm) to gap widths exhibiting complete mixing (0.5 mm) is defined. The implementation of gap sizes that are smaller than 0.5 mm (below the transition window) for passive mixing is suggested as a good strategy to obtain complete mixing and reproducible reaction yields on paper. In addition, the hourglass structure was used to define the ratio of reagents to be mixed (2 : 1, 1 : 1 and 1 : 2 HCl–NaOH) by simply varying the width ratio of the input channels of the paper. This allows easy adaptation of the device to reaction stoichiometry., Efficient passive mixing can be achieved by contricting the reagent flow using structures having narrow gaps.