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2. The Student Papers of Martin Luther King, Jr.: A Summary Statement on Research
- Published
- 1991
- Full Text
- View/download PDF
3. Peroxidase-Like Activity of Silver Nanoparticles Loaded Filter Paper and its Potential Application for Sensing
- Author
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Kuda Feke and Melisew Tadele Alula
- Subjects
Filter paper ,Thiocyanate ,Chemistry ,Nanochemistry ,General Chemistry ,Condensed Matter Physics ,Biochemistry ,Silver nanoparticle ,Catalysis ,Nanomaterials ,symbols.namesake ,chemistry.chemical_compound ,symbols ,General Materials Science ,Raman spectroscopy ,Hydrogen peroxide ,Nuclear chemistry - Abstract
Nanozymes are nanomaterials that possess intrinsic enzyme mimicking activity. In this study, the application of silver nanoparticles coated filter paper (AgNPs/FP) that exhibits a peroxidase-like catalytic activity as a potential sensor is reported. A simple chemical reduction method was used to produce AgNPs/FP. The formation of the particles on filter paper were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and surface-enhanced Raman spectroscopy (SERS). In the presence of hydrogen peroxide, AgNPs/FP oxidized the colorless o-phenylenediamine (OPD) and 3,3′,5,5′-tetramethylbenzidine (TMB) solutions to a yellow colored 2,3-diaminophenazine (DAP) and deep blue colored oxidized TMB (oxTMB), respectively. In the presence of thiocyanate, however, the peroxidase-like activity was inhibited in a concentration dependent manner. This makes the AgNPs/FP a promising catalyst and employed for colorimetric detection of thiocyanate via inhibition of the peroxidase-like activity. The application can be further extended to other environmentally and biologically important analytes.
- Published
- 2021
4. Locust bean gum adsorption onto softwood kraft pulp fibres: isotherms, kinetics and paper strength
- Author
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Jingqian Chen, Heather L. Trajano, and Rodger P. Beatson
- Subjects
Softwood ,Polymers and Plastics ,Chemistry ,Adsorption isotherms ,Pulp (paper) ,Locust bean gum ,Langmuir adsorption model ,engineering.material ,Northern bleached softwood kraft ,Hemicellulose ,Northern bleached softwood kraft pulp ,symbols.namesake ,chemistry.chemical_compound ,Adsorption kinetics ,Adsorption ,Paper strength additive ,Chemical engineering ,Kraft process ,Chemisorption ,symbols ,engineering ,Original Research - Abstract
The adsorption of locust bean gum (LBG) onto Northern Bleached Softwood Kraft (NBSK) pulp improved paper tensile and burst strength and lowered refining energy by strengthening inter-fibre bonding. Adsorption kinetics and isotherms were investigated to develop a fundamental understanding of the adsorption mechanism. The adsorption rate followed pseudo-second-order kinetics and the activation energy was 99.34 kJ·mol−1, suggesting chemisorption. The adsorption rate constant increased rapidly with temperature from 25 to 45 °C (k = 1.93 to 24.03 g·mg−1·min−1), but the amount adsorbed at equilibrium decreased (qe = 1.91 to 0.48 mg·g−1 o.d. fibre). LBG adsorption to NBSK at 25 °C was consistent with the Langmuir adsorption model for LBG n = 5.00, and the equilibrium constant Kf = 2.57 mg·g−1·(mg·L−1)−1/n at 25 °C. Favorable adsorption conditions for negatively charged LBG were identified: 25 °C for 10 min, low dosage level ( 150 r.p.m.), acidic or neutral conditions (pH 2–7) without salt addition. Graphic abstract
- Published
- 2021
5. Inkjet Printing of Ag and Polystyrene Nanoparticle Emulsions for the One-Step Fabrication of Hydrophobic Paper-Based Surface-Enhanced Raman Scattering Substrates
- Author
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Tiago Fernandes, Helena I. S. Nogueira, Natércia C.T. Martins, Sara Fateixa, and Tito Trindade
- Subjects
Surface (mathematics) ,Fabrication ,Materials science ,SERS ,Metal nanoparticles ,Nanoparticle ,Nanotechnology ,One-Step ,Paper based ,Paper sensors ,chemistry.chemical_compound ,symbols.namesake ,Hydrophobic surfaces ,chemistry ,symbols ,General Materials Science ,Polystyrene ,Pesticides ,Raman scattering ,Inkjet printing - Abstract
Hydrophobic substrates for surface-enhanced Raman scattering (SERS) of adsorbate species are of great interest in chemical analysis because they can concentrate the analyte molecules in a small area of the surface, thereby improving the SERS sensitivity. Here, we propose a general strategy to fabricate hydrophobic paper-based substrates for SERS applications. The paper substrates have been manufactured by inkjet printing of aqueous emulsions containing Ag and polystyrene (PS) colloidal nanoparticles. In a first stage, the SERS performance of the substrates was optimized by varying the relative amounts of polymer/metal colloidal nanoparticles, the number of printing layers, and the degree of hydrophobicity of the substrates, using crystal violet as a molecular probe, which is well known for its strong SERS activity. In these conditions, the strongest surface Raman enhancement was observed for the highest water contact angle (146°) achieved. The selected Ag/PS-coated paper substrates showed wide applicability for several analytes, but in this study, a detailed analysis is provided for the pesticide thiram as a proof of concept. Several samples spiked with thiram have been analyzed by SERS, giving a detection limit of 0.024 ppm thiram in mineral water and apple juice, while in apple peel, the detection limit achieved for the same pesticide was 600 ng/cm2. We suggest that this one-step fabrication method produces a hydrophobic coating whose nanoscale features improve the SERS performance of the paper substrates. published
- Published
- 2021
6. Characteristics of calcium lignin from pulping waste liquor and application for the treatment middle-stage wastewater of paper making
- Author
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Hao Yang, Guangzai Nong, Yijing Li, and Tian Zhu
- Subjects
Sodium ,chemistry.chemical_element ,macromolecular substances ,engineering.material ,Calcium ,complex mixtures ,law.invention ,chemistry.chemical_compound ,symbols.namesake ,Adsorption ,law ,Environmental Chemistry ,Lignin ,Calcination ,Waste Management and Disposal ,Water Science and Technology ,Lime ,fungi ,technology, industry, and agriculture ,food and beverages ,Langmuir adsorption model ,General Medicine ,Pulp and paper industry ,chemistry ,Wastewater ,engineering ,symbols - Abstract
In order to obtain a lignin-based adsorbent with low cost, simple operation and no further modification, a calcium lignin adsorbent was prepared from chemical mechanical pulping (CMP) waste liquor by directly calcification from lime. The calcium lignin was characterized by BET, SEM, TEM, FT-IR and solid-state NMR analyses. The results showed that the molecular structure of the calcium lignin particles did not change when compared to sodium lignin, the formation mechanism of calcium lignin was revealed. The initial COD and lignin contents of CMP waste liquid were 54858 mg/L and 24.39 g/L, the conversion rate of lignin can reach 71.36% when was deal with lime. Thus, most of the lignin resources in the waste liquid were recovered. The middle-stage wastewater (MSWW) of pulping and papermaking was dealt with calcium lignin, the COD removal rate was up to 85.83%. The adsorption isotherms and kinetics were well fitted by the Langmuir model and pseudo-second-order kinetic model, respectively. Lime was regenerated from the used calcium lignin with high-temperature calcination, the conversion rate of calcium ions can reach 83.56%. Overall, the calcium lignin prepared by the one-step method exhibited great potential for effectively removing COD from middle-stage wastewater.
- Published
- 2021
7. Kinetic analysis of the slow pyrolysis of paper wastes
- Author
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Mohit Kumar, Siddh Nath Upadhyay, Pradeep Kumar Mishra, and Garvit Bhardwaj
- Subjects
Thermogravimetric analysis ,Materials science ,Filter paper ,Renewable Energy, Sustainability and the Environment ,020209 energy ,Kinetic analysis ,Enthalpy ,Analytical chemistry ,02 engineering and technology ,010501 environmental sciences ,Atmospheric temperature range ,01 natural sciences ,Gibbs free energy ,symbols.namesake ,0202 electrical engineering, electronic engineering, information engineering ,symbols ,Standard protocol ,Pyrolysis ,0105 earth and related environmental sciences - Abstract
Thermochemical parameters of A4-sized printing paper (AP), filter paper (FP), newspaper (NP), writing paper (WP), and reed pith (RP) samples were estimated using standard protocol to identify its fuel characteristics, and thermal degradation of the same was studied using thermogravimetric analysis (TGA) and differential thermogravimetric (DTG) techniques in the temperature range of 30–800 °C at the heating rates of 10, 15, and 20 °C/min under nitrogen atmosphere. The curves of TGA and DTG exhibited four significant stages. Maximum weight loss was found to be in the second stage. Kinetic analysis was carried out in the conversion range of 0.1 to 0.7 using iso-conversational models of Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), Vyazovkin, and Vyazovkin AIC (V.AIC). The average activation energies were found to be 139.90, 115.93, 212.52, 257.41, and 241.63 kJ/mol using FWO; 129.73, 103.06, 202.46, 248.38, and 231.55 kJ/mol using KAS; 145.57, 134.00, 195.29, 256, and 241.63 kJ/mol using Vyazovkin; and 140.71, 133.86, 193.14, 247.57, and 190.14 kJ/mol using Vyazovkin AIC model. Thermodynamic parameters (enthalpy change (ΔH), Gibbs free energy change (ΔG), and entropy change (ΔS)) using these models have been evaluated.
- Published
- 2021
8. Equivalent Expressions Using CAS and Paper-and-Pencil Techniques
- Published
- 2014
- Full Text
- View/download PDF
9. Water absorption, flexural properties and morphological characterization of chicken feather fiber-wood sawdust hybrid reinforced waste paper-cement bio-composites
- Author
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Olanrewaju Seun Adesina, Taiwo Fisayo Omotosho, T.M.A. Olayanju, Isiaka Oluwole Oladele, Adeolu Adesoji Adediran, and I.M. Fasemoyin
- Subjects
010302 applied physics ,Cement ,Absorption of water ,Materials science ,Modulus ,Waste paper ,Young's modulus ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,symbols.namesake ,Flexural strength ,visual_art ,0103 physical sciences ,visual_art.visual_art_medium ,symbols ,Sawdust ,Fiber ,Composite material ,0210 nano-technology - Abstract
This work investigates the influence of blending waste paper and cement at fixed proportion with varying proportions of chicken feather fiber (CFF) and wood saw dust (WSD) as reinforcements. Samples produced were tested for flexural properties and water absorption potentials. The outcome showed that with increasing CFF content and reducing WSD content, water absorption reduced while flexural strength, modulus of ruptures (MOR) and modulus of elasticity (MOE) increases. MOR and MOE were at peaked when the ratio of CFF to WSD was 3:2 while flexural strength reached it crescendo at 4:1 of CFF to WSD. It was noticed that higher CCF content from 3 to 5 wt% gave better results in most of the investigated properties compared to WSD. Therefore, it was concluded that low quantity of WSD is needed to form a synergy with CFF in order to achieve optimum results. Well dispersed CFF-WSD phase in waste paper-cement based composites was observed to be responsible for the enhancement in the investigated properties.
- Published
- 2021
10. ISOTHERM, KINETICS AND THERMODYNAMICS ADSORPTION STUDIES OF DYE ONTO Fe3O4-WASTE PAPER ACTIVATED CARBON COMPOSITES
- Author
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Deswita Deswita, Rahma Dina Safitri, Sari Hasnah Dewi, Nurhasni Nurhasni, and Adel Fisli
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Materials science ,Kinetics ,General Engineering ,Magnetic separation ,Langmuir adsorption model ,Thermodynamics ,Waste paper ,Endothermic process ,chemistry.chemical_compound ,symbols.namesake ,Adsorption ,chemistry ,medicine ,symbols ,Composite material ,Methylene blue ,Activated carbon ,medicine.drug - Abstract
This paper focused on the studying of adsorption properties of Fe3O4-waste paper activated carbon composites for the removal of methylene blue dyes from water. The various parameters were carried out for the adsorption test of the composites, namely; contact time, adsorbent dose, initial MB concentration, pH solution, and temperature. The adsorption of isotherm, thermodynamics and kinetic was used to determine the characteristics of methylene blue adsorption onto the prepared adsorbent. The result indicates that the optimum adsorption capacity has occurred at pH = 6 in water solution. The adsorption capacity increase as the temperature increase until at 315K (45oC). The Langmuir isotherm is more appropriate to be applied as the adsorption model with the maximum adsorption capacity (qm) value of 101 and 93 mg/g for KA HCl-Fe3O4 and KA-Fe3O4 composites, respectively. The value of adsorption thermodynamic parameters was positive for ΔH, negative for ΔGo and positive for ΔSo, meaning the process adsorptions were endothermic, feasibility and spontaneity and randomness, respectively. The pseudo-second-order model was appropriate to predict the kinetic models for methylene blue adsorption onto the composites. The obtained adsorbent composites possess high adsorption efficiency and rapid magnetic separation. They were a promising for practical wastewater treatment for dyes removal from water.
- Published
- 2020
11. An Alpha Revisionist Manifesto: Concept White Paper
- Author
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Lichty, Patrick
- Published
- 2001
12. TOGA feature selection and the prediction of mechanical properties of paper from the Raman spectra of unrefined pulp
- Author
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Zahra Poursorkh, Najmeh Tavassoli, Edward R. Grant, and Paul Alexandre Bicho
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Discrete wavelet transform ,business.industry ,Computer science ,Pulp (paper) ,010401 analytical chemistry ,Feature selection ,02 engineering and technology ,Limiting ,engineering.material ,Covariance ,021001 nanoscience & nanotechnology ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,Analytical Chemistry ,symbols.namesake ,engineering ,symbols ,Process control ,Paper Makers ,0210 nano-technology ,Process engineering ,business ,Raman spectroscopy - Abstract
Process-monitoring laboratories in the pulp and paper industry generally use a combination of wet chemical analyses and physical measurements to certify the fitness of a production pulp for a specific end-use. These laboratory tests require time and the effort of trained personnel, limiting their utility for real-time process control. Here we show that Raman probes of unrefined cellulosic pulps, well-suited to the online measurement of in-process materials, can predict the quality attributes of manufactured papers. The accuracy of prediction improves when the covariance is modelled in a reduced measurement space selected by a data-driven, feature-selection technique referred to as a Template Oriented Genetic Algorithm (TOGA). TOGA, combined with discrete wavelet transform (DWT), isolates functional-group features that correlate best with mechanical properties paper derived from refined pulp. Paper makers refine market pulps to build sheet strength using a beating process that decreases freeness as it increases fibre-fibre bonding. Methods demonstrated here predict manufactured sheet properties obtainable after any specified degree of refining from the Raman spectrum of an unrefined pulp. This analysis capacity will enable both vendors of market pulp and makers of sheet paper to specify in advance the amount of beating required to produce a desired product, thereby saving cost and conserving resources.
- Published
- 2020
13. Surface-enhanced Raman scattering paper-based analytical devices
- Author
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Hugo Águas, Ana C. Marques, Elvira Fortunato, Rodrigo Martins, Bruno Costa-Silva, and Maria Goreti Ferreira Sales
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Surface (mathematics) ,symbols.namesake ,Materials science ,business.industry ,symbols ,Optoelectronics ,Paper based ,business ,Raman scattering - Published
- 2022
14. Paper-based flexible surface enhanced Raman scattering platforms and their applications to food safety
- Author
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Yen-Shi Lai, Chi-Yun Cheng, and Chia-Chi Huang
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Materials science ,010401 analytical chemistry ,Nanotechnology ,02 engineering and technology ,Paper based ,Substrate (printing) ,021001 nanoscience & nanotechnology ,01 natural sciences ,Surface conditions ,0104 chemical sciences ,Highly sensitive ,symbols.namesake ,Statistical analyses ,symbols ,Metal nanostructures ,0210 nano-technology ,Raman spectroscopy ,Raman scattering ,Food Science ,Biotechnology - Abstract
Background Surface enhanced Raman scattering (SERS) based on highly sensitive, flexible, solid-state sensors can provide molecular vibrational fingerprints of targeted substances in point-of-care (POC) analysis. Cellulose paper offers many advantages for the build-up of silver and gold nanostructures on a three-dimensional scaffold. Such composites can be made to contain SERS hot spots required for sensitive SERS detection in an active solid-state sensor. Scope and approach In this review, we discuss the key technical issues involved in the fabrication of SERS sensors combining a metallic SERS substrate and a cellulose paper support. We then survey recent literature for methods designed to address these issues with applications to support food safety where POC analysis serves as a valuable tool. Key findings and conclusions Sensitivity of detection is a primal challenge in the development of a paper-based SERS substrate. The fibril structures of paper materials, a suitable modification for improved bonding at the paper-metal interface, and the surface conditions of metal nanostructures all contribute to sensitive SERS performance on paper. Continuing expansion of spectrum collection in a database format, diverse methods for the statistical analyses of Raman spectra, and advanced integration of portable Raman instruments with the mobile tele-networks are critical in the further development of flexible SERS sensor in POC testing of food-borne substances.
- Published
- 2020
15. SERS Platform Based on Bimetallic Au-Ag Nanowires-Decorated Filter Paper for Rapid Detection of miR-196ain Lung Cancer Patients Serum
- Author
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Ji Xia, Yifan Liu, Menglin Ran, Xiaowei Cao, Youwei Wang, and Dan Lu
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Detection limit ,Article Subject ,Filter paper ,010401 analytical chemistry ,Succinic anhydride ,Cancer ,Substrate (chemistry) ,General Chemistry ,010402 general chemistry ,medicine.disease ,01 natural sciences ,0104 chemical sciences ,Chemistry ,chemistry.chemical_compound ,symbols.namesake ,chemistry ,microRNA ,medicine ,Biophysics ,symbols ,Lung cancer ,Raman spectroscopy ,QD1-999 - Abstract
Detecting microRNA (miRNA) biomarkers expression is of great significance for the diagnosis and treatment of lung cancer. Surface-enhanced Raman scattering (SERS) has achieved microRNA sensing for the diagnosis of primary liver cancers. In this work, we developed a SERS technology for the rapid detection of lung cancers-related miRNA (miR-196a) using bimetallic Au-Ag nanowire (AgNW@AuNPs) substrates coupled with the target hairpin DNA. The finite-difference time-domain simulation proved that a large number of “hot spots” were generated between the AgNW and AuNPs, which resulted in a huge enhancement of the signal of Raman reporters. Filter paper treated by hexadecenyl succinic anhydride hydrophobic and modified with AgNWs@AuNPs was used as capturing substrate. The detection limits of miR-196a in PBS and serum were as low as 96.58 aM and 130 aM, respectively. Studies on nonspecific sequence and single-base mismatch of miRNA demonstrated that SERS-based platform was highly selective, excellent uniform, and reproducible. Finally, the platform was used to show that the miR-196a expression in the serum of lung cancer patients was much higher than that in healthy people. The detection results indicated that the SERS platform had potential applications in cancer diagnosis and might be a viable alternative to the conventional miRNA detection method, the real-time polymerase chain reaction (RT-PCR) technology.
- Published
- 2020
16. Label-free Surface Enhanced Raman Scattering (SERS) on Centrifugal Silver Plasmonic Paper (CSPP): A Novel Methodology for Unprocessed Biofluids Sampling and Analysis
- Author
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Valter Sergo, Stefano Fornasaro, Alessandro Esposito, Alois Bonifacio, Esposito, Alessandro, Bonifacio, Aloi, Sergo, Valter, and Fornasaro, Stefano
- Subjects
Serum ,Bioanalysis ,Materials science ,Silver ,label-free SERS ,biofluids ,plasmonic paper ,vibrational spectroscopy ,serum ,Clinical Biochemistry ,biofluid ,Nanoparticle ,Metal Nanoparticles ,Nanotechnology ,Spectrum Analysis, Raman ,Article ,symbols.namesake ,Humans ,Colloids ,Plasmon ,Label free ,Reproducibility ,Reproducibility of Results ,Colloidal silver ,General Medicine ,symbols ,Raman scattering ,TP248.13-248.65 ,Localized surface plasmon ,Biotechnology - Abstract
Label-free SERS is a powerful bio-analytical technique in which molecular fingerprinting is combined with localized surface plasmons (LSPs) on metal surfaces to achieve high sensitivity. Silver and gold colloids are among the most common nanostructured substrates used in SERS, but since protein-rich samples such as serum or plasma can hinder the SERS effect due to protein–substrate interactions, they often require a deproteinization step. Moreover, SERS methods based on metal colloids often suffer from a poor reproducibility. Here, we propose a paper-based SERS sampling method in which unprocessed human serum samples are first soaked on paper strips (0.4 × 2 cm2), and then mixed with colloidal silver nanoparticles by centrifugation to obtain a Centrifugal Silver Plasmonic Paper (CSPP). The CSPP methodology has the potential to become a promising tool in bioanalytical SERS applications: it uses common colloidal substrates but without the need for sample deproteinization, while having a good reproducibility both in terms of overall spectral shape (r > 0.96) and absolute intensity (RSD < 10%). Moreover, this methodology allows SERS analysis more than one month after serum collection on the paper strip, facilitating storage and handling of clinical samples (including shipping from clinical sites to labs).
- Published
- 2021
17. Graphic Symbols as "The Mind on Paper": Links Between Children's Interpretive Theory of Mind and Symbol Understanding
- Author
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Myers, Lauren J. and Liben, Lynn S.
- Published
- 2012
- Full Text
- View/download PDF
18. Preparation and characterization of waste papers based composites and their applications in leather industries
- Author
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Hajer A. Ali, Rola A. K. Abbas, and Mahmood M. Barbooti
- Subjects
Wax ,Materials science ,business.product_category ,Absorption of water ,Pulp (paper) ,Young's modulus ,engineering.material ,Carton ,symbols.namesake ,Compressive strength ,Paraffin wax ,Dixon ,visual_art ,Waste paper, Leather industries ,visual_art.visual_art_medium ,symbols ,engineering ,cellulose-based composite ,lcsh:Q ,Composite material ,business ,lcsh:Science ,Earth-Surface Processes ,Shrinkage - Abstract
In this work, the utilization of waste paper in the preparation of cellulous-based composite is described, with latex as a binder. Paraffin wax and acrylic woven fibers were also used at various weight ratios to get the best mechanical and physical properties. The results were compared with the performance the Dixon, regularly used material in shoes manufacturing. The following tests were performed: compression resistance, density, water absorption, shrinkage, and moisture content. Manual method was employed in the preparation of test specimens in addition to laboratory forging machine for finishing of the specimens. Results of compression test (Modulus of elasticity, compressive strength, resistance to crushing) of the Specimens that contain pulp paper and reinforced with latex and acrylic fibers and low content of paraffin wax showed the highest resistance to compression, The increase of additives contents within the mix resulted in an increase in density. To mimic the real application conditions of the insole, the specimens were subjected to water absorption test by irrigation for 2 hours. The best specimen compositions for the water resistance test are those with high (5-10%) wax content due to the fact that the wax is a water repellent material. The shrinkage is another important parameter for the use of the composite in shoe industry. Result of shrinkage and humidity of all specimens show comparable results to commercially available and Dixon are also very close to the requirements of the specification of leather industry. However, in comparison with the available carton and dixon, our specimens contain from weight fraction (50g) waste pulp, (20g) latex, (4g) paraffin wax, (0.7g) acrylic fibers, proved comparable performance.
- Published
- 2019
19. Paper-microfluidics based SERS substrate for PPB level detection of catechol
- Author
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Krishna Chaitanya Vishnubhatla, Sai Manohar Chelli, Sai Muthukumar, Naresh Krishna Narasimha, Maurizio Ferrari, Siva Kumar Belliraj, and Abishek Hariharan
- Subjects
Materials science ,Microfluidics ,Ab initio ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,Hemocyanin ,01 natural sciences ,Silver nanoparticle ,Inorganic Chemistry ,symbols.namesake ,chemistry.chemical_compound ,Quinone complex ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Spectroscopy ,Catechol ,SERS ,MBTH ,Organic Chemistry ,Substrate (chemistry) ,Paper-microfluidics ,Paper based ,Surface-enhanced Raman spectroscopy ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,chemistry ,Catechol sensor ,symbols ,0210 nano-technology ,Raman spectroscopy - Abstract
The application of microfluidics for largescale rapid analytics holds great promise in the pharmaceutical diagnostics and analytical chemistry. Here we report a paper based microfluidic substrate designed by the impregnation of Silver nanoparticles. This study demonstrates the achievement of a thousand-fold increase in the successful detection level up to 10 ppb (90.8 nM) by employing Surface Enhanced Raman Spectroscopy (SERS) for the detection of Catechol. The presented sensor exhibits the following main features: (i) high specificity of enzyme (Hemocyanin)-based sensing, (ii) effective SERS sensitivity, (iii) easiness and cost-effectiveness of a paper-based platform. We rationalize these findings using the ab initio DFT simulations using Gaussian 09 whose theoretical calculations reflect the observed experimental Raman peaks.
- Published
- 2019
20. Ultra-stiff graphene oxide paper prepared by directed-flow vacuum filtration
- Author
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Kaiwen Hu, Francois Barthelat, Siyu Liu, and Marta Cerruti
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Materials science ,Structural material ,Flexural modulus ,Delamination ,Stiffness ,Young's modulus ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,symbols.namesake ,Flexural strength ,symbols ,medicine ,General Materials Science ,Composite material ,Deformation (engineering) ,medicine.symptom ,0210 nano-technology ,Graphene oxide paper - Abstract
Graphene oxide (GO) paper is an attracting structural material because of its high stiffness and light-weight. In order to exploit the high strength and stiffness of individual GO nanosheet into GO paper, the fabrication process must be optimized. In this study we fabricated ultra-stiff and strong GO paper by directed-flow vacuum filtration and compared its mechanical properties under different loading conditions. We also explored the effect of cross-linking with borax, thermal annealing and sonication to further enhance mechanical properties. The stiffest GO paper reported here has a tensile modulus of 109.9 GPa and a flexural modulus of 45.7 GPa. We also found that the flexural modulus of GO paper is significantly lower than the tensile modulus because of interlayer shearing, micro-buckling and delamination during flexural deformation. The properties of GO papers therefore need to be carefully selected for mechanical structures where flexion is the major deformation. This study provides significant insights about improving mechanical properties of GO paper and selecting GO paper for different loading conditions.
- Published
- 2020
21. Paper-Based SERS Sensing Platform Based on 3D Silver Dendrites and Molecularly Imprinted Identifier Sandwich Hybrid for Neonicotinoid Quantification
- Author
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Peihua Zhu, Huanying Liu, Shenguang Ge, Jinghua Yu, Peini Zhao, and Lina Zhang
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Paper ,Silver ,Materials science ,Surface Properties ,Metal Nanoparticles ,Nanotechnology ,02 engineering and technology ,Spectrum Analysis, Raman ,01 natural sciences ,Silver nanoparticle ,Neonicotinoids ,symbols.namesake ,Limit of Detection ,General Materials Science ,Plasmon ,Detection limit ,010401 analytical chemistry ,Molecularly imprinted polymer ,Nitro Compounds ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Microscopy, Electron, Scanning ,symbols ,Dendrite (metal) ,0210 nano-technology ,Science, technology and society ,Layer (electronics) ,Raman scattering - Abstract
Real-time monitoring of neonicotinoid pesticide residues is of great significance for food security and sustainable development of the ecological environment. Herein, a paper-based surface-enhanced Raman scattering (SERS) amplified approach was proposed by virtue of multilayered plasmonic coupling amplification. The unique plasmonic SERS multilayer was constructed using three-dimensional (3D) silver dendrite (SD)/electropolymerized molecular identifier (EMI)/silver nanoparticle (AgNP) sandwich hybrids with multiple hotspots and a strong electromagnetic field in nanogaps. Dendritelike 3D silver materials with remarkably high accessible surface areas and the lightning rod effect constituted the first-order enhancement of paper-based sensors. Molecular identifiers coated upon an SD layer as the interlayer were used for target capture and enrichment. Subsequently, AgNPs featuring rough surface and local plasma resonance decorated as the top layer formed the secondary enhancement of the amplification strategy. As the most brilliant part, dendritelike 3D silver coupled with AgNPs has established double Ag layers to accomplish a multistage enhancement of SERS signals based on the superposition of their electromagnetic fields. Owning to the distinctive design of the multiple coupling amplification strategy, the fabricated SERS paper chips demonstrated impressive specificity and ultrahigh sensitivity in the detection of imidacloprid (IMI), with a detection limit as low as 0.02811 ng mL-1. More importantly, the multiple SERS enhancement paper chip holds great potential for automated screening of a variety of contaminants.
- Published
- 2020
22. A Circuital Model-Based Analysis of Moisture Content in Oil-Impregnated-Paper Insulation Using Frequency Domain Spectroscopy
- Author
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Feng Yang and Lin Du
- Subjects
Physical model ,Materials science ,General Computer Science ,Moisture ,General Engineering ,Dielectric ,Oil-impregnated-paper insulation ,extended Debye model ,symbols.namesake ,frequency domain spectroscopy ,Bushing ,moisture ,symbols ,General Materials Science ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,Biological system ,Water content ,Condenser (heat transfer) ,lcsh:TK1-9971 ,Debye model ,Parametric statistics - Abstract
The explicitly numerical or well-defined correlations between the dielectrics responses (DRs) and dielectric essences of oil-impregnated paper (OIP) insulation have not been fully understood yet. As a result, it is rather difficult to quantitatively diagnose the critical insulation condition, like determining moisture content in insulation paper (MCP) of power equipment only using electrical-based techniques such as frequency domain spectroscopy (FDS). To obtain MCP value, from a new perspective of parametric study on the circuital DR equivalence of OIP insulation-extended Debye model (EDM), the present contribution introduces a novel approach by exploring the pattern when EDM parameters vary with MCP and temperatures T. Further, mathematical correlations are developed between sensitive R-C values and MCP-T values. On the above analysis, small-scale physical models of real-life transformer bushings were prepared as test samples. Their OIP condenser bodies were artificially absorbed different controlled quantities of moisture and conditioned at different temperatures to record corresponding FDS results. Then a hybrid genetic algorithm combined with the Levenberg-Marquardt algorithm was proposed to estimate the EDM parameters by fitting the measured FDS data. Sensitive parameters therein were identified using subspectrum decomposition and formulated with MCP-T values so that a reliable moisture content estimation can be achieved once the testing temperature and FDS recordings of an insulation body are known.
- Published
- 2020
23. New Result on the Feedback Capacity of the Action-Dependent Dirty Paper Wiretap Channel
- Author
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Guangfen Xie and Bin Dai
- Subjects
Computer science ,Science ,QC1-999 ,Gaussian ,0211 other engineering and technologies ,General Physics and Astronomy ,02 engineering and technology ,Astrophysics ,Interference (wave propagation) ,Upper and lower bounds ,Article ,symbols.namesake ,action encoder ,wiretap channel ,Control theory ,Secrecy ,0202 electrical engineering, electronic engineering, information engineering ,021110 strategic, defence & security studies ,Physics ,Transmitter ,020206 networking & telecommunications ,channel feedback ,Action (physics) ,QB460-466 ,symbols ,intelligent reflecting surfaces ,State (computer science) ,dirty paper channel ,Communication channel - Abstract
The Gaussian wiretap channel with noncausal state interference available at the transmitter, which is also called the dirty paper wiretap channel (DP-WTC), has been extensively studied in the literature. Recently, it has been shown that taking actions on the corrupted state interference of the DP-WTC (also called the action-dependent DP-WTC) helps to increase the secrecy capacity of the DP-WTC. Subsequently, it has been shown that channel feedback further increases the secrecy capacity of the action-dependent DP-WTC (AD-DP-WTC), and a sub-optimal feedback scheme is proposed for this feedback model. In this paper, a two-step hybrid scheme and a corresponding new lower bound on the secrecy capacity of the AD-DP-WTC with noiseless feedback are proposed. The proposed new lower bound is shown to be optimal (achieving the secrecy capacity) and tighter than the existing one in the literature for some cases, and the results of this paper are further explained via numerical examples.
- Published
- 2021
- Full Text
- View/download PDF
24. Synthesis of free-standing silver nanoparticles coated filter paper for recyclable catalytic reduction of 4-nitrophenol and organic dyes
- Author
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Bokang Present, Melisew Tadele Alula, Mothusi Madiba, and Peter Lemmens
- Subjects
Polymers and Plastics ,Filter paper ,4-Nitrophenol ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Silver nanoparticle ,0104 chemical sciences ,Catalysis ,Rhodamine 6G ,chemistry.chemical_compound ,symbols.namesake ,Sodium borohydride ,chemistry ,Chemical engineering ,Reagent ,symbols ,0210 nano-technology ,Raman spectroscopy - Abstract
The utilization of nitrophenols as raw materials for the synthesis of dyes, explosives, pesticides, and pharmaceuticals has increased the presence of nitrophenols as pollutants in industrial and agricultural wastewater. Similarly, the wide application range of rhodamine 6G and methylene blue enable their potential as pollutants of surface and ground waters. Both classes of chemicals can change water ecosystems dangerously. In this study, filter paper-based silver nanoparticles are prepared as catalysts for reduction of 4-nitrophenol to 4-aminophenol and for degradation of rhodamine 6G and methylene blue. This method avoids utilization of toxic reagents and is simple and inexpensive. The formation of the silver nanoparticles on filter paper was characterized using different techniques, such as scanning electron microscopy, X-ray diffraction, and surface-enhanced Raman spectroscopy. In the presence of sodium borohydride, the silver nanoparticles coated filter paper was able to reduce 4-nitophenol to 4-aminophenol within a short period of time. It has been found that, the nanocatalyst can be recycled and recovered from the reaction solutions easily without losing its high efficiency. Additionally, we demonstrated the potential of the substrate to study the in situ reduction reaction via surface-enhanced Raman spectroscopy.
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- 2019
25. Performance enhancement of paper-based SERS chips by shell-isolated nanoparticle-enhanced Raman spectroscopy
- Author
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Lianqing Zhu, Mingze Sun, Jinhong Guo, Xiaojia Liu, Binghan Li, Taotao Mu, Jiayin Chen, and Xing Ma
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Detection limit ,Spectrum analyzer ,Fabrication ,Materials science ,Polymers and Plastics ,Filter paper ,Mechanical Engineering ,Metals and Alloys ,Nanoparticle ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,symbols.namesake ,Mechanics of Materials ,Materials Chemistry ,Ceramics and Composites ,symbols ,Sample collection ,0210 nano-technology ,Raman spectroscopy ,Raman scattering - Abstract
Paper-based flexible surface-enhanced Raman scattering (SERS) chips have been demonstrated to have great potential for future practical applications in point-of-care testing (POCT) due to the potentials of massive fabrication, low cost, efficient sample collection and short signal acquisition time. In this work, common filter paper and Ag@SiO2core-shell nanoparticles (NP) have been utilized to fabricate SERS chips based on shell‐isolated nanoparticle‐enhanced Raman spectroscopy (SHINERS). The SERS performance of the chips for POCT applications was systematically investigated. We used crystal violet as the model molecule to study the influence of the size of the Ag core and the thickness of the SiO2coating layer on the SERS activity and then the morphology optimized Ag@SiO2core-shell NPs was employed to detect thiram. By utilizing the smartphone as a miniaturized Raman spectral analyzer, high SERS sensitivity of thiram with a detection limit of 10−9M was obtained. The study on the stability of the SERS chips shows that a SiO2shell of 3 nm can effectively protect the as-prepared SERS chips against oxidation in ambient atmosphere without seriously weakening the SERS sensitivity. Our results indicated that the SERS chips by SHINERS had great potential of practical application, such as pesticide residues detection in POCT.
- Published
- 2019
26. Vegetal fiber paper matrix impregnated with silica gel for benzene removal
- Author
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Ruzhu Wang, X.N. Wu, Tianshu Ge, and Yanjun Dai
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Paper ,Environmental Engineering ,Materials science ,010504 meteorology & atmospheric sciences ,Silica Gel ,010501 environmental sciences ,engineering.material ,01 natural sciences ,Matrix (chemical analysis) ,symbols.namesake ,chemistry.chemical_compound ,Adsorption ,Coating ,Fiber ,Benzene ,Plant Proteins ,0105 earth and related environmental sciences ,Pressure drop ,Air Pollutants ,Silica gel ,Public Health, Environmental and Occupational Health ,Langmuir adsorption model ,Building and Construction ,chemistry ,Chemical engineering ,Air Pollution, Indoor ,engineering ,symbols ,Feasibility Studies - Abstract
Removing benzene from indoor space plays an important role in indoor air purification. A novel filter with vegetal fiber paper (VFP) as matrix hosting silica gel is proposed in this paper for benzene removal. In order to investigate the feasibility and performance of this idea, firstly, three pieces of VFP samples impregnated with different amounts of silica gel are fabricated and their benzene adsorption quantities are tested. The results show that three times is recommended as the optimal number for impregnating. The VFP sample impregnated with silica gel after the third impregnating exhibits commendable coating stability and good benzene adsorption performance. Additionally, at low relative pressure (Pb /Ps ≤ 0.05), the experimental data of benzene adsorption isotherms fit well with the Langmuir model with R2 greater than 0.97. Then, two actual filters made of VFP impregnated with silica gel after the third impregnating were fabricated. It is found that the pressure drop of the actual filter is only 1200 Pa/m when the air velocity is 2 m/s. Besides, the one-pass efficiency of the filter can reach to 19.44%. It is expected that the silica gel coated on the filter can be modified to improve the purification performance of the filter.
- Published
- 2019
27. Research Paper Search Using a Topic-Based Boolean Query Search and a General Query-Based Ranking Model
- Author
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Yoichi Tomiura, Emi Ishita, and Satoshi Fukuda
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050101 languages & linguistics ,Information retrieval ,Computer science ,05 social sciences ,Rank (computer programming) ,InformationSystems_INFORMATIONSTORAGEANDRETRIEVAL ,Information needs ,02 engineering and technology ,Search recall ,Latent Dirichlet allocation ,Set (abstract data type) ,Search engine ,symbols.namesake ,Ranking ,0202 electrical engineering, electronic engineering, information engineering ,symbols ,020201 artificial intelligence & image processing ,0501 psychology and cognitive sciences ,Latent Dirichlet Allocation ,Word (computer architecture) ,Boolean conjunctive query ,Research paper search - Abstract
When conducting a search for research papers, the search should return comprehensive results related to the user’s query. In general, a user inputs a Boolean query that reflects the information need, and the search engine ranks the research papers based on the query. However, it is difficult to anticipate all possible terms that authors of relevant papers might have used. Moreover, general query-based ranking methods emphasize how to rank the relevant documents at the top of the results, but require some means of guaranteeing the comprehensiveness of the results. Therefore, two ranking methods that consider the comprehensiveness of relevant papers are proposed. The first uses a topic-based Boolean query search. This search converts every word in the abstract set and query into a topic via topic analysis by Latent Dirichlet Allocation (LDA) and conducts a search at the topic level. The topic assigned to synonyms of a search term is expected to be the same as that assigned to the search term. Each paper is ranked based on the number of times it is matched with each topic-based Boolean query search executed for various LDA parameter settings. The second is a hybrid method that emphasizes better results from our topic-based ranking result and a general query-based ranking result. This method is based on the observation that the paper sets retrieved by our method and by a general ranking method will be different. Through experiments using the NTCIR-1 and -2 datasets, the effectiveness of our topic-based and hybrid methods are demonstrated.
- Published
- 2019
28. Rapid detection of malachite green residues in fish using a surface-enhanced Raman scattering-active glass fiber paper prepared by in situ reduction method
- Author
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Hui Chen, Hua Li, Qiuyuan Lin, Zhipeng Huang, Di Deng, Jilie Kong, and Yunyan Kuang
- Subjects
Paper ,Surface Properties ,Glass fiber ,Food Contamination ,02 engineering and technology ,Spectrum Analysis, Raman ,01 natural sciences ,Silver nanoparticle ,Analytical Chemistry ,chemistry.chemical_compound ,symbols.namesake ,Rosaniline Dyes ,Animals ,Particle Size ,Malachite green ,Detection limit ,010401 analytical chemistry ,Fishes ,Substrate (chemistry) ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Silver nitrate ,chemistry ,symbols ,Glass ,0210 nano-technology ,Raman spectroscopy ,Raman scattering ,Nuclear chemistry - Abstract
Food safety issues, especially those related to drug residues, have caused concern in recent years. Malachite green (MG), which is frequently used as ectoparasiticide, fungicide, and antiseptic in fish farming, is poisonous and carcinogenic. Several technologies and methods have been developed to accurately detect MG, but they can be time-consuming and expensive. Herein, we prepared a glass fiber paper as a surface-enhanced Raman scattering substrate for rapid and convenient detection of MG residues in fish. Uniform silver nanoparticles were deposited on the glass fiber paper by two in situ reduction steps of silver nitrate. The Raman signal of MG was detected and recorded using a portable Raman spectrometer in 10 s. There was a good linear relationship between the surface-enhanced Raman scattering signal intensity and the concentration of MG between 1 × 10−7 and 1 × 10−5 mol/L and the limit of detection was 5 × 10−10 mol/L. Residual MG in fish samples was extracted and detected with a recovery rate range of 98.9–119.4%. This method provides a novel way to detect MG in fish.
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- 2019
29. Research paper classification systems based on TF-IDF and LDA schemes
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Sang-Woon Kim and Joon-Min Gil
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Scheme (programming language) ,General Computer Science ,Computer science ,LDA ,K-means clustering ,02 engineering and technology ,Latent Dirichlet allocation ,lcsh:QA75.5-76.95 ,symbols.namesake ,0202 electrical engineering, electronic engineering, information engineering ,lcsh:Information theory ,Cluster analysis ,tf–idf ,computer.programming_language ,Information retrieval ,Paper classification ,business.industry ,TF-IDF ,Information technology ,020206 networking & telecommunications ,Class (biology) ,lcsh:Q350-390 ,Term (time) ,ComputingMethodologies_PATTERNRECOGNITION ,symbols ,020201 artificial intelligence & image processing ,lcsh:Electronic computers. Computer science ,business ,computer - Abstract
With the increasing advance of computer and information technologies, numerous research papers have been published online as well as offline, and as new research fields have been continuingly created, users have a lot of trouble in finding and categorizing their interesting research papers. In order to overcome the limitations, this paper proposes a research paper classification system that can cluster research papers into the meaningful class in which papers are very likely to have similar subjects. The proposed system extracts representative keywords from the abstracts of each paper and topics by Latent Dirichlet allocation (LDA) scheme. Then, the K-means clustering algorithm is applied to classify the whole papers into research papers with similar subjects, based on the Term frequency-inverse document frequency (TF-IDF) values of each paper.
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- 2019
30. A facile low-cost paper-based SERS substrate for label-free molecular detection
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Sung-Gyu Park, Yong-Ill Lee, Ho Sang Jung, Dongho Kim, Jaebum Choo, Jungil Moon, Vasanthan Devaraj, Vo Thi Nhat Linh, ChaeWon Mun, and Jin-Woo Oh
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Materials science ,Nanostructure ,Nanoparticle ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,symbols.namesake ,Materials Chemistry ,Electrical and Electronic Engineering ,Instrumentation ,Detection limit ,chemistry.chemical_classification ,Filter paper ,Biomolecule ,Metals and Alloys ,Substrate (chemistry) ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry ,symbols ,0210 nano-technology ,Raman spectroscopy ,Raman scattering - Abstract
We introduce a facile and low-cost method for fabricating gold nanostructures on cellulose filter paper (CFP) to prepare a paper-based surface-enhanced Raman scattering (SERS) sensor for label-free molecular detection. Polymerized dopamine (PD) was used as an adhesive layer on the CFP and simultaneously functioned as a reducing agent for gold nanoparticle (AuNP) nucleation. The size of the AuNPs was dependent on the pH of the gold precursor solution, and nanoparticles with an average size of 102 nm were formed on the PD-coated CFP at a pH 3, exhibiting high SERS activity. Finite-difference time-domain (FDTD) simulations of the electromagnetic field enhancement of AuNPs with different sizes and interparticle distances were performed to identify the origin of the SERS effect. The developed paper-based SERS substrate showed uniform and excellent molecular sensitivity with a limit of detection (LOD) of 10−7 M for methylene blue, as measured by a portable Raman spectrometer. Furthermore, as a field application test, surfaces of apples were pretreated with diquat (DQ) and paraquat (PQ) pesticides, which were then detected down to a concentration of 1 ppm after simple attachment of the sensor on the apple peels and performing a SERS measurement. The developed paper-based SERS sensor is expected to be applicable as a label-free sensor for a variety of chemical and biological molecules.
- Published
- 2019
31. A Feynman–Kac approach to a paper of Chung and Feller on fluctuations in the coin-tossing game
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Sergio Grunbaum and F alberto Grunbaum
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Discrete mathematics ,symbols.namesake ,Coin flipping ,Applied Mathematics ,General Mathematics ,symbols ,Feynman diagram ,Mathematics - Abstract
A classical result of K. L. Chung and W. Feller deals with the partial sums S k S_k arising in a fair coin-tossing game. If N n N_n is the number of “positive” terms among S 1 S_1 , S 2 S_2 , …, S n S_n then the quantity P ( N 2 n = 2 r ) P(N_{2n} = 2r) takes an elegant form. We lift the restriction on an even number of tosses and give a simple expression for P ( N 2 n + 1 = r ) P(N_{2n+1} = r) , r = 0 r = 0 , 1 1 , 2 2 , …, 2 n + 1 2n+1 . We get to this ansatz by adaptating the Feynman–Kac methodology.
- Published
- 2022
32. Recycled waste paper–cement composite panels reinforced with kenaf fibres: durability and mechanical properties
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Samson Omokaro Osadolor and Stephen Amiandamhen
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Cement ,Materials science ,biology ,Composite number ,0211 other engineering and technologies ,Young's modulus ,Waste paper ,02 engineering and technology ,010501 environmental sciences ,biology.organism_classification ,01 natural sciences ,Durability ,Kenaf ,symbols.namesake ,Flexural strength ,Mechanics of Materials ,symbols ,Statistical analysis ,021108 energy ,Composite material ,Waste Management and Disposal ,0105 earth and related environmental sciences - Abstract
There is a growing interest on recycling of waste fibres as an alternative to landfill disposal. The aim of the study was to investigate the durability and mechanical properties of waste paper–cement composite panels reinforced with varying kenaf fibre content (FC, 2–10%). The panels produced were evaluated for properties including modulus of rupture (MOR) and apparent modulus of elasticity (MOE). The resistance of the panels was tested in the field for both termite damage and fungi decay for a period of 24 weeks. Accelerated decay test was also performed on selected samples. The results showed that the mean MOR ranged from 3.17 MPa for samples with 10% FC to 4.84 MPa for samples with 8% FC. The mean MOE ranged from 248 MPa for samples with 10% FC to 1298.1 MPa for samples with 8% FC. Statistical analysis showed that the effect of the fibre content was significant on the properties evaluated (p
- Published
- 2020
33. Paper swab based SERS detection of non-permitted colourants from dals and vegetables using a portable spectrometer
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Aditya Kumar and Venugopal Santhanam
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Paper ,Silver ,Sample (material) ,Food Contamination ,Nanotechnology ,02 engineering and technology ,Spectrum Analysis, Raman ,01 natural sciences ,Biochemistry ,Analytical Chemistry ,symbols.namesake ,Molecular level ,Vegetables ,Rosaniline Dyes ,Environmental Chemistry ,Sample preparation ,Coloring Agents ,Spectroscopy ,Adulterant ,Spectrometer ,Rhodamines ,Chemistry ,010401 analytical chemistry ,Analytical technique ,Peas ,Chemical Engineering ,Surface-enhanced Raman spectroscopy ,021001 nanoscience & nanotechnology ,Nanostructures ,0104 chemical sciences ,symbols ,Capsicum ,0210 nano-technology ,Raman spectroscopy ,Azo Compounds - Abstract
Rising concern about the use of non-permitted colourants, in common food items such as dals and green vegetables sold in Indian markets, have led to a demand for low-cost point-of-use chemical analysis tools. Conventional food-analysis techniques involving tedious sample preparation protocols are not suited for in-field applications. Surface Enhanced Raman Spectroscopy (SERS) is an analytical technique that is well-suited for point-of-use chemical analysis with molecular level detection capability, which can also serve as a quality assurance tool for businesses. Effective and rapid signal collection from a large-area sample within a field-setting using disposable, low-cost SERS substrates is a key challenge in implementing such a solution. Herein, we demonstrate the use of inkjet-printed thin films comprising of robust nanostructured-silver as flexible, paper-based SERS (P-SERS) swabs for the direct detection of Metanil Yellow (MY) from toor dal (yellow split pigeon peas) samples and Malachite Green (MG) from green peas and green chillies. The macroscopic uniformity of these thin-films in combination with a portable Raman spectrometer equipped with orbital raster scanning (ORS™) technology for signal collection results in an unprecedented precision (RSD ∼ 1.6%) upon characterizing samples saturated with Rhodamine-6G (R6G), a standard Raman probe. As several food-cleansing products have appeared in the marketplace, the adulterant removal efficacy of some commercially available ‘washes’ as well as products such as ‘ozoniser’, which was determined by SERS characterization of swabs before and after use, is also reported.
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- 2019
34. Gaussian Process Regression for Quantitative DP Analysis of Oil-paper Insulation by NIRS Detection
- Author
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Chen Wang, Han Li, Guan-Jun Zhang, Wen-Bo Zhang, and Yuan Li
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Training set ,Computer science ,Electrical insulation paper ,law.invention ,symbols.namesake ,law ,Kriging ,Ground-penetrating radar ,symbols ,Statistical analysis ,Transformer ,Gaussian process ,Algorithm ,Reliability (statistics) - Abstract
Oil-paper insulation is the key insulation structure of the transformers, whose aging condition is closely related to the operations of the equipment. The degree of polymerization (DP) is the direct parameter characterizing the aging condition of oil-paper insulation. Recently, the near infrared spectroscopy (NIRS) measurement powered by quantitative analysis is used to evaluate DP of the insulating papers mainly. While the applications of NIRS for DP evaluation is constrained because the present spectral quantitative analysis method is not accurate and stable enough, especially for onsite tests. In this paper, we propose a Gaussian process regression (GPR) method to predict DP of the oil- paper insulation in laboratory as well as in field. Firstly, the basic principles of GPR algorithm are illustrated. A GPR model for DP prediction is established based on the spectra of differently aged insulating paper samples which are prepared in laboratory. The GPR model show a high prediction accuracy both for training set and testing set. The established GPR model is finally applied on the DP prediction of insulating papers originating from a de-tanked transformer. The accurate predicted DP and the reliable aging assessment results indicate that the established model can be implemented on site.
- Published
- 2021
35. An activation energy-based method for assessing the aging state of cellulose insulating paper under the synergistic effect of mechanical stress and heat
- Author
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Changyun Li, Jiahua Dong, Xin Cao, Minling Xu, and Wei Wang
- Subjects
Arrhenius equation ,Steady state ,Materials science ,Electrical insulation paper ,Activation energy ,law.invention ,Vibration ,symbols.namesake ,law ,Insulation system ,symbols ,Translation factor ,Composite material ,Transformer - Abstract
Oil-paper insulation is an important component of the oil-immersed power transformer, and its insulation life is directly related to the operating life of the transformer. Therefore, it is particularly important to accurately assess the life of the oil-paper insulation system. In this paper, aging insulation paper samples with different mechanical stresses were prepared in an aging vibration chamber under laboratory conditions, and the activation energy under the synergistic machine-thermal action was obtained using the translation factor. The Arrhenius equation was then combined with the Ekenstam equation to derive an equation that can accurately determine the degree of polymerization of the oil-paper insulation system. It is proved that this equation can predict the degree of polymerization of the paper under the synergistic action of machine and heat, and can provide theoretical support for the evaluation of paper life.
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- 2021
36. Raman Diagnosis Method for Thermal Aging of Insulating Paper Based on AE-LDA and Naive Bayes
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Weiran Zhou, Zewei Wang, Fu Wan, Weigen Chen, and Dingkun Yang
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Materials science ,business.industry ,Feature extraction ,Electrical insulation paper ,Pattern recognition ,Thermal aging ,Linear discriminant analysis ,Autoencoder ,Naive Bayes classifier ,symbols.namesake ,symbols ,Condensed Matter::Strongly Correlated Electrons ,Artificial intelligence ,business ,Raman spectroscopy ,Transformer (machine learning model) - Abstract
In this paper, we obtain samples of thermal aging transformer insulation paper at 6 time points through an accelerated thermal aging test that simulates the actual operating state of the transformer. The Raman spectroscopy diagnosis model of transformer insulating paper aging is proposed. The model combines an autoencoder and a linear discriminant analysis algorithm to extract the characteristics of the Raman spectrum, and uses a Naive Bayes classification method to divide the aging stage of the insulating paper. Through the Raman spectroscopy diagnosis model of transformer insulation paper aging designed in this paper, the Raman spectroscopy characteristic quantity extracted by the AE-LDA method can effectively reflect the aging characteristic information of the insulating paper, and the Naive Bayes classification algorithm is used to predict. Research shows that the model has a high predictive accuracy for the assessment of the aging state of insulating paper, and can effectively diagnose the aging state of transformer oil-paper insulation. The Raman spectroscopy used in the diagnosis of the aging of insulating paper has good aging discrimination ability and good application prospects, and provides a new idea for the diagnosis of the aging state of transformer oil-paper insulation.
- Published
- 2021
37. Application of Plasma-Printed Paper-Based SERS Substrate for Cocaine Detection
- Author
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Kostya Ostrikov, Anthony B. Murphy, Jinghua Fang, Shanlin Fu, F Isa, Linda Xiao, Avi Bendavid, Rhiannon Alder, Edith Chow, Jungmi Hong, Bryony Ashford, and Christophe Comte
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Materials science ,paper substrate ,illicit drugs ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,lcsh:Chemical technology ,01 natural sciences ,Biochemistry ,Article ,Analytical Chemistry ,symbols.namesake ,X-ray photoelectron spectroscopy ,lcsh:TP1-1185 ,on-site testing ,Electrical and Electronic Engineering ,Instrumentation ,Detection limit ,SERS ,plasma printing ,010401 analytical chemistry ,Substrate (chemistry) ,Paper based ,Plasma ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,forensics ,chemistry ,Colloidal gold ,cocaine detection ,gold nanoparticles ,symbols ,0210 nano-technology ,Raman spectroscopy ,Carbon - Abstract
Surface-enhanced Raman spectroscopy (SERS) technology is an attractive method for the prompt and accurate on-site screening of illicit drugs. As portable Raman systems are available for on-site screening, the readiness of SERS technology for sensing applications is predominantly dependent on the accuracy, stability and cost-effectiveness of the SERS strip. An atmospheric-pressure plasma-assisted chemical deposition process that can deposit an even distribution of nanogold particles in a one-step process has been developed. The process was used to print a nanogold film on a paper-based substrate using a HAuCl4 solution precursor. X-ray photoelectron spectroscopy (XPS) analysis demonstrates that the gold has been fully reduced and that subsequent plasma post-treatment decreases the carbon content of the film. Results for cocaine detection using this substrate were compared with two commercial SERS substrates, one based on nanogold on paper and the currently available best commercial SERS substrate based on an Ag pillar structure. A larger number of bands associated with cocaine was detected using the plasma-printed substrate than the commercial substrates across a range of cocaine concentrations from 1 to 5000 ng/mL. A detection limit as low as 1 ng/mL cocaine with high spatial uniformity was demonstrated with the plasma-printed substrate. It is shown that the plasma-printed substrate can be produced at a much lower cost than the price of the commercial substrate.
- Published
- 2021
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38. TiO2/Ag2O immobilized on cellulose paper: A new floating system for enhanced photocatalytic and antibacterial activities
- Author
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Valeria La Parola, Sami Boufi, Mouheb Sboui, Hinda Lachheb, Michelangelo Gruttadauria, Soraa Bouattour, Leonarda F. Liotta, and Mouheb Sboui, Hinda Lachheb, Soraa Bouattour, Michelangelo Gruttadauria, Valeria La Parola, Leonarda Francesca Liotta, Sami Boufi
- Subjects
Paper ,Materials science ,010501 environmental sciences ,01 natural sciences ,Biochemistry ,03 medical and health sciences ,symbols.namesake ,chemistry.chemical_compound ,0302 clinical medicine ,Aniline ,X-ray photoelectron spectroscopy ,TiO2–Ag2O heterojunction ,Paper TiO2-Ag2O heterojunction Self-cleaning Surface functionalization Floating photocatalyst ,030212 general & internal medicine ,Cellulose ,0105 earth and related environmental sciences ,General Environmental Science ,chemistry.chemical_classification ,Aromatic amine ,Settore CHIM/06 - Chimica Organica ,Chemical engineering ,chemistry ,Surface functionalization ,symbols ,Photocatalysis ,Degradation (geology) ,Surface modification ,Raman spectroscopy ,Self-cleaning ,Floating photocatalyst - Abstract
Paper-TiO2-Ag2O floating photocatalysts were produced under mild condition and their photocatalytic activity for the degradation of aromatic amine under sunlight stimulant was investigated. Characterizations by Raman, XRD, XPS, DRS and PL confirmed the presence of TiO2 and Ag2O, and the morphology of the appended TiO2/Ag2O layer was probed by FE-SEM. The photocatalytic activity of the prepared samples was investigated by the degradation of aniline (AN) in water under simulated sun-light illumination and constrained conditions, i.e. non-stirring and non-oxygenation. The presence of Ag2O combined with TiO2 was shown to improve the resistance of paper to bacteria attack, thus increasing the durability of the photocatalyst. Thanks to its hydrophobic character, the paper-TiO2-Ag2O NPs can be employed as useful floating photocatalyst and can be reused in continuous cycles.
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- 2021
39. Integrating van der Waals materials on paper substrates for electrical and optical applications
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Jose R. Ares, João Elias Figueiredo Soares Rodrigues, Isabel J. Ferrer, Martin Lee, José Antonio Alonso, Carmen Munuera, Tao Wang, Andres Castellanos-Gomez, Carlos Sánchez, Herre S. J. van der Zant, Javier Gainza, Riccardo Frisenda, Qinghua Zhao, Eduardo Flores, Wenliang Zhang, UAM.Departamento de Física de Materiales, Instituto Universitario de Ciencia de Materiales Nicolás Cabrera (INC), and Materiales de Interés en Energias Renovables: Sistema Solar-H2
- Subjects
Drawn ,Fabrication ,Materials science ,SB2S3 ,FOS: Physical sciences ,02 engineering and technology ,Substrate (electronics) ,Applied Physics (physics.app-ph) ,010402 general chemistry ,Transistors ,01 natural sciences ,Paper-based electronics ,symbols.namesake ,Van der Waals materials ,General Materials Science ,Electronics ,Optical Properties ,Óptica ,Electrical properties ,Optical properties ,Condensed Matter - Materials Science ,INKS ,business.industry ,Sensors ,Electrical Properties ,Materials Science (cond-mat.mtrl-sci) ,Física ,Physics - Applied Physics ,Orders of magnitude (numbers) ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Rubbing ,Semiconductor ,Van Der Waals Materials ,visual_art ,Electronic component ,visual_art.visual_art_medium ,symbols ,Optoelectronics ,Graphite ,van der Waals force ,Graphene ,0210 nano-technology ,business ,Paper-Based Electronics - Abstract
Paper holds the promise to replace silicon substrates in applications like internet of things or disposable electronics that require ultra-low-cost electronic components and an environmentally friendly electronic waste management. In the last years, spurred by the abovementioned properties of paper as a substrate and the exceptional electronic, mechanical and optical properties of van der Waals (vdW) materials, many research groups have worked towards the integration of vdW materials-based devices on paper. Recently, a method to deposit a continuous film of densely packed interconnects of vdW materials on paper by simply rubbing the vdW crystals against the rough surface of paper has been presented. This method utilizes the weak interlayer vdW interactions and allows cleaving of the crystals into micro platelets through the abrasion against the paper. Here, we aim to illustrate the general character and the potential of this technique by fabricating films of 39 different vdW materials (including superconductors, semi-metals, semiconductors, and insulators) on standard copier paper. We have thoroughly characterized their optical properties showing their high optical quality: one can easily resolve the absorption band edge of semiconducting vdW materials and even the excitonic features present in some vdW materials with high exciton binding energy. We also measured the electrical resistivity for several vdW materials films on paper finding exceptionally low values, which are in some cases, orders of magnitude lower than those reported for analogous films produced by inkjet printing. We finally demonstrate the fabrication of field-effect devices with vdW materials on paper using the paper substrate as an ionic gate., Comment: 4 figures in main text, 21 figures in Supp. Info
- Published
- 2021
40. On Some Features in the Hereditary Transmission of the Self-Black and the "Irish" Coat Characters in Rats.--Paper I
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- 1908
41. Plasmonic Paper Microneedle Patch for On-Patch Detection of Molecules in Dermal Interstitial Fluid
- Author
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Sisi Cao, Chandana Kolluru, Rohit Gupta, Hamed Gholami Derami, Mikayla Williams, Mark R. Prausnitz, Richard K. Noel, Qisheng Jiang, and Srikanth Singamaneni
- Subjects
Paper ,Materials science ,Injections, Intradermal ,Bioengineering ,Nanotechnology ,02 engineering and technology ,Spectrum Analysis, Raman ,Proof of Concept Study ,01 natural sciences ,Article ,Rhodamine 6G ,chemistry.chemical_compound ,symbols.namesake ,Interstitial fluid ,Animals ,Molecule ,Instrumentation ,Plasmon ,Fluid Flow and Transfer Processes ,Nanotubes ,Filter paper ,Rhodamines ,Process Chemistry and Technology ,010401 analytical chemistry ,Extracellular Fluid ,Dermis ,Surface-enhanced Raman spectroscopy ,021001 nanoscience & nanotechnology ,Rats ,0104 chemical sciences ,chemistry ,Needles ,Point-of-Care Testing ,symbols ,Polystyrenes ,Female ,Nanorod ,Gold ,0210 nano-technology ,Raman scattering - Abstract
Minimally invasive devices to detect molecules in dermal interstitial fluid (ISF) are desirable for point-of-care diagnostic and monitoring applications. In this study, we developed a microneedle (MN) patch that collects ISF for on-patch biomarker analysis by surface-enhanced Raman scattering (SERS). The micrometer-scale MNs create micropores in the skin surface, through which microliter quantities of ISF are collected onto plasmonic paper on the patch backing. The plasmonic paper was prepared by immobilizing poly(styrenesulfonate) (PSS) coated gold nanorods (AuNRs) on a thin strip of filter paper using plasmonic calligraphy. Negatively charged PSS was used to bind positively charged rhodamine 6G (R6G), which served as a model compound, and thereby localize R6G on AuNR surface. R6G bound on the AuNR surface was detected and quantified by acquiring SERS spectra from the plasmonic paper MN patch. This approach was used to measure pharmacokinetic profiles of R6G in ISF and serum from rats in vivo. This proof-of-concept study indicates that a plasmonic paper MN patch has the potential to enable on-patch measurement of molecules in ISF for research and future medical applications.
- Published
- 2019
42. Integrating superconducting van der Waals materials on paper substrates
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Andres Castellanos-Gomez, Martin Lee, Herre S. J. van der Zant, Mar García-Hernández, Riccardo Frisenda, Jon Azpeitia, Federico Mompean, Damian Bouwmeester, and Wenliang Zhang
- Subjects
Materials science ,FOS: Physical sciences ,Superconductors ,Van der Waals materials ,Paper substrates ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Superconductivity (cond-mat.supr-con) ,symbols.namesake ,Deposition (phase transition) ,Electrical performance ,General Materials Science ,Electronics ,Crystalline silicon ,Superconductivity ,Condensed Matter - Materials Science ,Condensed matter physics ,Condensed Matter - Superconductivity ,Materials Science (cond-mat.mtrl-sci) ,021001 nanoscience & nanotechnology ,Engineering physics ,0104 chemical sciences ,Chemistry ,Chemistry (miscellaneous) ,Meissner effect ,visual_art ,Electronic component ,visual_art.visual_art_medium ,symbols ,van der Waals force ,0210 nano-technology - Abstract
Paper has the potential to dramatically reduce the cost of electronic components. In fact, paper is 10 000 times cheaper than crystalline silicon, motivating the research to integrate electronic materials on paper substrates. Among the different electronic materials, van der Waals materials are attracting the interest of the scientific community working on paper-based electronics because of the combination of high electrical performance and mechanical flexibility. Up to now, different methods have been developed to pattern conducting, semiconducting and insulating van der Waals materials on paper but the integration of superconductors remains elusive. Here, the deposition of NbSe2, an illustrative van der Waals superconductor, on standard copy paper is demonstrated. The deposited NbSe2 films on paper display superconducting properties (e.g. observation of Meissner effect and resistance drop to zero-resistance state when cooled down below its critical temperature) similar to those of bulk NbSe2., Paper has the potential to dramatically reduce the cost of electronic components but the integration of electronic materials is challenging. Here the integration of NbSe2, a van der Waals superconductor, on paper is demonstrated.
- Published
- 2021
43. Axisymmetric acoustophoresis for paper pulp concentration
- Author
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Pierre Gelinas, Maxime Bilodeau, Romain Le Magueresse, Robert Schiavi, Tamara Krpic, and Nicolas Quaegebeur
- Subjects
Materials science ,Acoustics and Ultrasonics ,QC221-246 ,02 engineering and technology ,engineering.material ,Acoustic levitation ,01 natural sciences ,Inorganic Chemistry ,Paper pulp concentration ,symbols.namesake ,stomatognathic system ,Pulp flow simulation ,Stokes' law ,Acoustophoresis ,Chemical Engineering (miscellaneous) ,Environmental Chemistry ,Radiology, Nuclear Medicine and imaging ,Original Research Article ,Acoustic radiation force ,QD1-999 ,Turbulence ,Pulp (paper) ,Papermaking ,010401 analytical chemistry ,Organic Chemistry ,Acoustics. Sound ,Mechanics ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Chemistry ,stomatognathic diseases ,Fiber suspension flow ,symbols ,engineering ,Particle ,Particle size ,0210 nano-technology - Abstract
Highlights • Numerical simulations of acoustophoresis in pulp flow is conducted. • Parametric study of fiber characteristics, pulp flow regimes and acoustic parameters are conducted. • A feasibility study of industrial acoustophoresis for pulp concentration is performed. • A potential concentration gain of 15% is obtained experimentally., In pulp and paper mills, mechanical processes such as screening and washing are commonly used to remove accumulated solid suspensions and concentrate the pulp. For environmental reasons and to optimize paper production, an emerging challenge is to develop alternative methods to concentrate paper pulp between 3 % and 6 % consistency for which the mixed pulp-water flow is complex. Among the proposed solutions in the literature, solutions based on acoustic levitation, also referred as acoustophoresis, of low-consistency pulp have been demonstrated as a potential solution for efficient pulp concentration and water recirculation. However, no sensitivity analysis on the ultrasound and physical parameters was proposed, limiting the extension to a realistic application. Thus, this paper presents a numerical modeling of acoustophoresis for pulp flow concentration in a pipe. For this purpose, the pulp flow is defined as a pseudo-homogenous fluid with a turbulent Low Re k- ∊ formalism, and the pulp particles are considered spherical and deflected by two acoustic forces, namely the acoustic radiation force and the Stokes drag force, both induced by an ultrasound wave generated along the walls of a circular pipe. The combined action of these two forces in the pulp flow enables to concentrate the particles at the center of the pipe. The influences of particle size and mechanical properties, fluid properties and ultrasound parameters are analyzed within a parametric study to optimize the particle deflection and the pulp concentration. The experimental feasibility of the industrial use of acoustophoresis for the concentration of paper pulp is demonstrated with a concentration gain up to 15 %.
- Published
- 2021
44. Enabling Direct Protein Detection in a Drop of Whole Blood with an 'On-Strip' Plasma Separation Unit in a Paper-Based Lateral Flow Strip
- Author
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Jennifer Boryczka, Sujan Kasani, Xuefei Gao, and Nianqiang Wu
- Subjects
Detection limit ,Paper ,Chemistry ,010401 analytical chemistry ,Metal Nanoparticles ,Plasma ,010402 general chemistry ,Silicon Dioxide ,Spectrum Analysis, Raman ,01 natural sciences ,0104 chemical sciences ,Analytical Chemistry ,Carcinoembryonic Antigen ,symbols.namesake ,Membrane ,Interference (communication) ,Filter (video) ,symbols ,Humans ,Gold ,Raman spectroscopy ,Sensitivity (electronics) ,Biomedical engineering ,Whole blood ,Reagent Strips - Abstract
Conventional paper lateral flow assays have low sensitivity and suffer from severe interference from complex human fluid sample matrices, which prevents their practical application in the testing of whole blood samples in the point-of-care settings. To solve this problem, gold nanostar@Raman reporter@silica-sandwiched nanoparticles have been developed as the surface-enhanced Raman scattering (SERS) probes for sensing transduction; and a functionalized filter membrane assembly has been designed and constructed in the paper-based lateral flow strip (PLFS) as a built-in plasma separation unit. In this "on-strip" plasma separation unit, three layers of filter membranes are stacked and surface-modified to maximize the separation efficiency and the plasma yield. As a result, the integrated PLFS has been successfully used for the detection of carcinoembryonic antigen (CEA) in 30 μL of whole blood with the assistance of a portable Raman reader, achieving a limit of detection of 1.0 ng mL-1. In short, this report presents an inexpensive, disposable, portable, and field-deployable paper-based device as a general point-of-care testing tool for protein biomarker detection in a drop of whole blood.
- Published
- 2020
45. Direct Characterization of Thermal Nonequilibrium between Optical and Acoustic Phonons in Graphene Paper under Photon Excitation
- Author
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Xinwei Wang, Ridong Wang, Hamidreza Zobeiri, Tianyu Wang, and Nicholas J.R. Hunter
- Subjects
Photon ,Materials science ,Phonon ,thermal nonequilibrium ,General Chemical Engineering ,Science ,General Physics and Astronomy ,Medicine (miscellaneous) ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Biochemistry, Genetics and Molecular Biology (miscellaneous) ,Raman thermometry ,symbols.namesake ,Thermal conductivity ,Wavenumber ,General Materials Science ,Laser power scaling ,Absorption (electromagnetic radiation) ,phonon coupling factor ,Research Articles ,Condensed matter physics ,General Engineering ,graphene paper ,021001 nanoscience & nanotechnology ,optical and acoustic phonons ,0104 chemical sciences ,symbols ,0210 nano-technology ,Raman spectroscopy ,Excitation ,Research Article - Abstract
Raman spectroscopy has been widely used to measure thermophysical properties of 2D materials. The local intense photon heating induces strong thermal nonequilibrium between optical and acoustic phonons. Both first principle calculations and recent indirect Raman measurements prove this phenomenon. To date, no direct measurement of the thermal nonequilibrium between optical and acoustic phonons has been reported. Here, this physical phenomenon is directly characterized for the first time through a novel approach combining both electrothermal and optothermal techniques. While the optical phonon temperature is determined from Raman wavenumber, the acoustic phonon temperature is precisely determined using high‐precision thermal conductivity and laser power absorption that are measured with negligible nonequilibrium among energy carriers. For graphene paper, the energy coupling factor between in‐plane optical and overall acoustic phonons is found at (1.59–3.10) × 1015 W m−3 K−1, agreeing well with the quantum mechanical modeling result of 4.1 × 1015 W m−3 K−1. Under ≈1 µm diameter laser heating, the optical phonon temperature rise is over 80% higher than that of the acoustic phonons. This observation points out the importance of subtracting optical–acoustic phonon thermal nonequilibrium in Raman‐based thermal characterization., The optical–acoustic phonon thermal nonequilibrium is first probed through novel electrothermal and optothermal techniques. For graphene paper, the optical‐acoustic phonon energy coupling factor is found at (1.59–3.10) × 1015 W m−3 K−1, agreeing well with theoretical predictions. Under ≈1 µm laser heating, the optical phonon temperature rise is over 80% higher than that of the acoustic phonons.
- Published
- 2020
46. Graphene paper with electrodeposited NiCo2S4 nanoparticles as a novel flexible sensor for simultaneous detection of folic acid and ascorbic acid
- Author
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Elif Erçarıkcı, Zeriş Aksu, Ezgi Topçu, and Kader Dağcı Kıranşan
- Subjects
Materials science ,Graphene ,Mechanical Engineering ,Oxide ,Nanoparticle ,General Chemistry ,Ascorbic acid ,Electronic, Optical and Magnetic Materials ,law.invention ,symbols.namesake ,chemistry.chemical_compound ,X-ray photoelectron spectroscopy ,Chemical engineering ,chemistry ,law ,Electrode ,Materials Chemistry ,symbols ,Electrical and Electronic Engineering ,Raman spectroscopy ,Graphene oxide paper - Abstract
We studied the production and electrochemical performance of NiCo2S4 electrodeposited reduced graphene oxide (rGO) paper for use as a freestanding flexible electrode for the simultaneous determination of folic acid (FA) and ascorbic acid (AA). Production of rGO paper was achieved through vacuum filtration of the aqueous dispersion of graphene oxide, followed by chemical reduction in hydrogen iodide solution. NiCo2S4/rGO paper material was fabricated with a simple approach using electrodeposition of hydrothermal synthesized NiCo2S4 nanoparticles directly on rGO paper. The physicochemical properties of as-prepared flexible NiCo2S4/rGO paper were characterized by means of field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray powder diffraction patterns. This freestanding paper electrode demonstrated high sensitivity, a wide linear range, and a low detection limit towards the simultaneous detection of FA and AA. NiCo2S4/rGO paper sensor, possessing easy preparation, low cost, and high flexibility, was tested in real samples with promising recoveries. This study exhibited that the approach of the electrodeposition of bimetallic sulfides on freestanding graphene paper substrates has great potential to develop high-performance flexible electrochemical sensors.
- Published
- 2022
47. A quick and simple paper-based method for detection of furfural and 5-hydroxymethylfurfural in beverages and fruit juices
- Author
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Sandeep K. Sharma, Pawankumar Rai, and Srishti Mehrotra
- Subjects
integumentary system ,General Medicine ,Paper based ,Improper storage ,Furfural ,Analytical Chemistry ,Maillard Reaction ,Beverages ,Fruit and Vegetable Juices ,Maillard reaction ,symbols.namesake ,chemistry.chemical_compound ,Rendering (animal products) ,chemistry ,5-hydroxymethylfurfural ,symbols ,Humans ,Fruit juice ,Furaldehyde ,Food science ,Food Science - Abstract
Improper storage and transportation of non-alcoholic beverages can, over longer periods, induce Maillard reaction, degrading nutritional components and generating genotoxic and carcinogenic by-products such as furfural and 5-hydroxymethylfurfural (HMF), rendering products unsafe for human consumption. Here, we describe a rapid quantitative solution-based method and test-strips for detection of furfural and HMF. The standard spectroscopic method indicated an LOD of 0.006 ± 0.003 % (v/v) and 0.005 ± 0.002 % (v/v) for furfural and HMF, respectively in fruit juice samples. The novel chromogenic test-strip has sensitivity of 0.008 % (v/v) and 0.004 % (v/v) for furfural and HMF, respectively in the same samples of fruit juice. Thus, the developed method and test-strips were specific for furfural and HMF and can be used to help ensure food safety and quality in various industrial applications.
- Published
- 2021
48. Pyrolysis behaviour, kinetics and thermodynamic data of hydrothermal carbonization–Treated pulp and paper mill sludge
- Author
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Yuming Wen, Weihong Yang, Henry Hammarström, Pär Jönsson, and Shule Wang
- Subjects
060102 archaeology ,Renewable Energy, Sustainability and the Environment ,Chemistry ,020209 energy ,Activated complex ,Thermal decomposition ,06 humanities and the arts ,02 engineering and technology ,Gibbs free energy ,symbols.namesake ,Hydrothermal carbonization ,Chemical engineering ,Yield (chemistry) ,0202 electrical engineering, electronic engineering, information engineering ,symbols ,0601 history and archaeology ,Heat of combustion ,Pyrolytic carbon ,Pyrolysis - Abstract
Organic-rich pulp and paper mill sludge (PPMS) has the potential to become a renewable carbon source for producing alternatives to fossil-based product. In this work, PPMS treated by hydrothermal carbonization (HTC) was investigated based on its pyrolysis properties. The pyrolytic mechanism, kinetics data and product of the sample were studied using TG as well as pyrolysis tests in Py-GC/MS and a bench-scale reactor at 450, 550, and 650 °C. The results show that the thermal decomposition of feedstock is a two-stage reaction. The mean activation energy of the pyrolysis of HTC treated PPMS was estimated as 233.08 kJ/mol, which is higher than that of the pyrolysis of paper sludge reported before. The changes in enthalpies, entropies and Gibbs free energies from the reactants to the activated complex were estimated. The concentration of monocyclic aromatic hydrocarbons in the derived organic liquid fraction shows a positive correlation with the pyrolysis temperature. At 550 °C, the organic liquid fraction reached its highest yield at 13.7% with an oxygen level of 10.7 wt% and a higher heating value of 35.9 MJ/kg. The pyrolytic chars show that a molar ratio of O:C is less than 0.2, which shows potential for use as a carbon sink.
- Published
- 2021
49. Investigation of wafers used as paper binding in the academician von Struve manuscripts
- Author
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A. V. Kurochkin, D. V. Pankin, S. Rongonen, А. Povolotckaia, L. Rylkova, T. Tkachenko, А. Mikhailova, N. Dovedova, and Evgenii Borisov
- Subjects
Archeology ,Prussian blue ,Materials science ,Massicot ,Polymer science ,Materials Science (miscellaneous) ,Conservation ,Absorbance ,symbols.namesake ,chemistry.chemical_compound ,Colored ,chemistry ,Chemistry (miscellaneous) ,symbols ,Wafer ,Raman spectroscopy ,General Economics, Econometrics and Finance ,Spectroscopy ,Hue - Abstract
This work is devoted to the study of the composition of such a characteristic object for the 17–19 centuries as wafers, which were used to join sheets of paper in documents or to seal letters. Owing to the limited information in the literature and possible degradation processes that may occur with them in this paper, the modern optical techniques were applied to gain information about them. As the object of the investigation the wafers found in the hand-written documents of Academician Friedrich Georg Wilhelm von Struve (Vasily Yakovlevich Struve 1793–1864) were chosen (Fund number 721, the RAS Archive, Saint-Petersburg branch, Struve V.). Besides the common way it was found that a large number of colored wafers were used to join several sheets in one composite elongated document and also to make correction on top of what was written. As the part of a major task aimed at maintaining the fund documents dated 19th century and the stability of the used joining wafers in particular the Raman and UV–Vis absorbance spectroscopies were applied in order to investigate wafers chemical composition. It was found the use of two different types of pigments for orange hues. One of them is cinnabar and another one is made up of red lead and massicot mixture. The Prussian blue was used for wafers with dark blue hue and as a mixture with massicot for green hue. According to UV–Vis absorbance spectroscopy it was found the use of anthraquinone type pigment for the red, rose and purple hues. The presence of the wafers with different base materials were determined by means of the Raman spectroscopy, namely of the vegetable (presumably starch) and protein (presumably gelatin) origin. The obtained results were compared with the data available in the previous researches, including the recipes given in the publications of the 19th century.
- Published
- 2021
50. Conduct Unbecoming , by Maurice Punch . : Tavistock , 1985 , 220 pp., $13.00 (paper) .
- Author
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Manning, P.K.
- Published
- 1986
- Full Text
- View/download PDF
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