Explore the vast range of titles available.

This work describes the synthesis of red-emitting copper nanoclusters (CuNCs) by using DNA as the template. DNA-templated CuNCs combined with blue-emitting carbon dots (CDs) form the self-assembled complex DNA-CuNC/CDs through electrostatic interactions. In the presence of arginine (Arg), the blue fluorescence of CDs (with excitation/emission maxima at 350/440 nm) is quenched. Addition of acetaminophen (AP) induces the competitive combination of Arg and AP for the CDs. This results in the release of Arg from CDs and the recovery of blue fluorescence. On addition of both Arg and AP, the red fluorescence of CuNCs (with excitation/emission maxima at 350/670 nm) undergoes only slight changes. Hence, the DNA-CuNC/CD complex can serve as a dually emitting ratiometric probe to determine both Arg and AP, with detection limits of 0.35 μM and 0.26 μM, respectively. The probe also enables on-site, visual determination of Arg and AP in aqueous samples, best by placing the system in cuvettes or dropping it onto filter paper strips. An “INHIBIT” logic gate was designed based on this ratiometric and visual fluorometric assay, with Arg and AP as the inputs. Graphical abstract Schematic presentation of self-assembly of DNA-templated copper nanoclusters and carbon dots to construct novel dual-emitting nanoprobes for ratiometric fluorometric and visual determination of arginine and acetaminophen in aqueous solutions and on wetting filter paper strips.

A facile, fast, and economically viable method has been used to synthesize highly active copper (Cu) nanoparticles in chitosan (CH) coating layers over cellulose microfibers of filter paper (FP). FP was coated with 1 wt% CH solution (CH-FP) and kept in CuSO 4 aqueous solution to adsorb Cu 2+ ions. The Cu 2+ loaded CH-FP was treated with 0.1 M NaBH 4 aqueous solution to reduce the ions to Cu 0 nanoparticles. The Cu 0 loaded CH-FP (Cu/CH-FP) was characterized by FE-SEM, XRD, TGA and ATR-FTIR, which indicated the successful preparation of the Cu 0 nanoparticles by this method. The crystallinity of cellulose was not affected during the preparation process, which indicated that the Cu 0 nanoparticles were present in the amorphous thin CH layer around the cellulose microfibers of FP. The Cu/CH-FP was used in aqueous medium as an efficient catalyst for the reduction of toxic organic dyes. Our current study involved the degradation of methyl orange (MO) and Congo red (CR) dyes in the presence of NaBH 4 . The rate constants of 0.2683 and 0.1655 min −1 were observed for the MO and CR reductions. Besides good catalytic activity, the Cu/CH-FP catalyst strip could be easily recovered as compared to the other methods that are currently used. Recovery was accomplished by simply pulling the Cu/CH-FP strip from the reaction medium after completion of the reaction. The recovered Cu/CH-FP could be recycled several times provided that its exposure time to the air was minimal.

Re-use of a catalyst is an important task, which is usually achieved by loading it on easily separable supports such as magnetic substrates. However, we demonstrate here the process of easy and fast catalyst separation from a reaction medium by loading it onto an economically feasible and microscopically high surface substrate of filter paper (FP) made up of cellulose microfibers as catalyst support. To achieve the goal, we coated chitosan (CH) on filter paper (CH-FP) to impart a high affinity of the substrate for metal ion absorption. AgNO 3 dissolved in water with a 0.1 M concentration was used as the Ag ion carrier solution, and CH-FP strips with known rectangular dimensions were submerged into it for the metal ion absorption. The metal ion-laden CH-FP strips were dip treated with sodium borohydride (NaBH 4 ) aqueous solution to prepare Ag-nanoparticle loaded CH-FP (Ag/CH-FP). X-ray diffraction and energy dispersive X-ray spectroscopy confirmed the formation of the Ag/CH-FP hybrid. Ag/CH-FP morphology was examined through scanning electron microscopy analysis, which showed the presence of Ag nanoparticles attached to the cellulose microfibers. The prepared Ag/CH-FP was employed as a dip catalyst for the degradation of nitroarene compounds of 2-nitophenol (2-NP) and 4-nitrophenol (4-NP) by NaBH 4 . Remarkably, the rate constants for 4-NP and 2-NP were 3.9 × 10 −3 and 1.7 × 10 −3  s −1 , respectively. In addition, we discussed the ease of the catalyst retrievability from the reaction mixture and its re-usability.

A high-performance electromagnetic interference (EMI) shielding material based on carbon nanofiber (CNF) and cellulose filter (CF) paper has been fabricated by a cost-efficient and convenient dip-coating method. The EMI shielding performance of the CF papers with micron level thickness tolerance (2.5–12.7 µm) have been explored by considering the microstructure, serviceability, electrical conductivity, and number of dip-coating cycles. Field emission scanning electron microscopy of the surface and edge of the composites support the good electrical conductivity, which showed distinct increment in electrical conductivity from 6.6 × 10 −7 to 0.85 S/cm. The number of dip-coating cycles have a significant impact on electrical conductivity, and this has also been studied and inferred after alteration of dipping cycles. The electromagnetic shielding efficiency of CNF-coated CF paper exhibits 24.6 dB with only 25 dip coating cycles. Moreover, from commercially viable points of view, extensive study has been executed to investigate CNF-coated CF papers in the simulated ageing environments viz. water, thermal ageing, and thermo-degradability over a wide range of temperature (ambient to 600 °C). All the environmental factors have been simulated on a laboratory scale. The CNF-coated CF papers possess significantly higher mechanical properties than pure CF paper. This type of conductive CNF-coated CF paper is a promising candidate to be used as highly flexible, lightweight, and cost-efficient EMI shielding material in advanced multifunctional application areas.

The drift ratio is a key indicator of the water-saving performance of cooling towers. However, quantitative experimental studies on the drift ratio remain limited. To address this issue, this study establishes a drift rate test platform and conducts 96 experiments on the droplet loss of water caused by drift loss and droplet dripping, using a mechanical draft wet model tower and the filter paper moisture absorption method. The characteristics of the drift droplets and floating water volume are analyzed, along with the variation patterns of the drift ratio, and a three-variable prediction model is proposed. Experimental results indicate that the drift ratio of cooling towers is not governed by a single factor, but is jointly influenced by the nozzle diameter, water drenching density, and sectional wind velocity, exhibiting nonlinear behavior. Among these factors, the nozzle diameter plays a critical role, while the sectional wind velocity and water drenching density exert a synergistic regulatory effect. Detailed analysis reveals that increasing the sectional wind velocity consistently results in a nonlinear increase in the drift ratio. With increasing sectional wind velocity, small-diameter nozzles (D ≤ 34 mm) produce higher drift ratios than large-diameter nozzles (D ≥ 36 mm). Moreover, as the water drenching density increases, the drift ratios of small-diameter nozzles rise and peak at 13 t/(h·m²), whereas those of large-diameter nozzles decrease, peaking at 7 t/(h·m²). To further quantify the influence of these factors, an exponential regression model for the drift ratio is developed as a function of the water drenching density and sectional wind velocity, grouped by nozzle diameter, achieving a goodness of fit exceeding 98%. This study provides a valuable reference for nozzle selection and water-saving design in wet cooling towers for engineering applications.

The loss of ovarian estrogen production in postmenopausal women causes vaginal dryness and irritation. The contraceptive depot-medroxyprogesterone acetate (DMPA) likewise promotes vaginal dryness by suppressing ovulation and reducing estrogen production. Though vaginal dryness in women is typically identified by self-report, research with preclinical models will benefit from development of new methodology that objectively measures vaginal moisture. Strips of calibrated filter paper, similar to those used to quantify lachrymal secretions, were intravaginally placed in untreated ovary-intact mice, DMPA-treated ovary-intact mice, and ovariectomized (OVX) mice to measure vaginal fluid levels. As anticipated, levels of circulating estradiol were significantly lower in DMPA-treated and OVX mice vs. estrus-stage mice. Congruent with the loss of estrogen, median readings on calibrated filter paper strips collected from DMPA-treated (1 mm) and OVX mice (1 mm) were significantly lower than the median reading from estrus-stage mice (10 mm); ( P  < 0.0001 for both comparisons). Current findings indicate that calibrated filter paper provides objective measure of vaginal moisture in mice and suggest that the hypoestrogenemia produced in mice by DMPA injection or ovariectomization models the vaginal dryness detected in women with reduced levels of circulating estrogen.

To reduce the fire risk of air filter paper, a reactive ammonium phosphite flame retardant was synthesized and applied to the flame-retarding treatment of air filter paper. It was found that ammonium phosphite reacted with cellulose existing in filter paper fibers to form P–O–C bonds and remarkably improved the flame-retarding properties and thermal stability of the air filter paper. After modification of the air filter paper with 30 wt% of ammonium phosphite, its limiting oxygen index value reached 39.5%, which remained at 29.6% after 4 h of the dipping test. The heat release rate and total heat release rate of the treated air filter paper decreased significantly, and the carbon residual amounts at 700 °C in the nitrogen atmosphere and in air reached 43.96% and 16.35%, respectively. During thermal decomposition, ammonium phosphite played a flame-retarding role in both condensed and gas phases. Moreover, ammonium phosphite, as a flame retardant, had no obvious influence on the physical properties and filtration performance of the air filter paper.

Researchers have created a modern infrared (IR) sensor that is both super-sensitive and highly flexible. This remarkable device possesses impressive properties of exceptional sensitivity (24,000%), high responsiveness (1.25 A/W), and fast response time (3 ms). This innovation stands out for its unique construction: an ultrathin layer of lead sulfide (PbS) deposited on a standard Whatman filter paper. This design achieves a photo-current 32 times greater than previous record-holding PbS thin films. The key advantage is its unmatched flexibility. This sensor can bend and flex without breaking, maintaining its IR detection capabilities even after enduring extreme bending cycles. This breakthrough paves the way for a new era of wearable IR photo sensors, flexible electronics, and medical applications.

Compacted loess soil is used as a geo-material in many engineering projects, such as building foundations and highway embankments. Water infiltration characteristics and post settlement of the compacted loess in large construction projects of Northwest China have received increasing attention from researchers and investors. These behaviors are closely related to the soil water characteristics. This study aims to investigate the soil water characteristic curves (SWCCs) of compacted loess soil with different dry densities and to reveal the responsible micro-mechanisms for soil water characteristics. Loess soil collected from the new district of Yan’an City, China, is prepared into five dry density groups. The SWCC of each group in the suction range of 0–105 kPa is measured using the filter paper method (FPM). Two-dimensional (2D) images and the pore size distribution (PSD) curves of the specimens are tested by scanning electron microscopy (SEM) and the mercury pressure method (MIP), respectively. The results of this study highlight that the compaction behavior mainly influences the pores with a radius (r) in the range of 1–10 μm, and has no influence on the pores of r < 0.5 μm. The particle shapes among the five dry densities groups are similar. The characteristics of the PSD curves of the compacted loess soil correspond well to the SWCCs. The suction of the SWCCs increases with increasing dry density in the lower suction range of 0–100 kPa. In contrast, suction among the five dry density groups is almost identical in the suction range exceeding 100 kPa. The results of the study are helpful to understand the SWCC and microstructure characteristics of compacted loess with different dry densities.

Background The factors affecting the quality of histopathologic specimens obtained via small intestinal endoscopic biopsy (SIEB) remain unclear. Hypothesis/Objectives To identify factors related to the quality of histopathologic specimens obtained via SIEB. Animals Histopathologic duodenal and ileal specimens were obtained from 116 dogs and 38 cats that underwent SIEB for diagnostic purposes. Methods This retrospective study analyzed 3354 individual histopathologic specimens scored using the grading system of histopathologic adequacy (GSHA). A lower GSHA score indicates lower quality specimens. Univariate and multivariate ordinal logistic models were used to assess the relationship between the GSHA score of the specimens and various explanatory factors, including fixation method, biopsy forceps size, biopsy site, and histopathologic diagnosis. The generalized estimating equation method was used to account for the clustering of specimens among animals. Results Multivariate models using the specimens showed that filter paper fixation of endoscopic samples resulted in a higher GSHA score than floating fixation in both dogs (ordinal odds ratio [OR]: 0.19; 95% confidence interval [CI]: 0.15–0.25) and cats (ordinal OR: 0.19; 95% CI: 0.13–0.29). In dogs, the scores were lower for duodenal specimens than for ileal specimens and for specimens obtained using smaller forceps. In cats, the scores were lower for ileal specimens than for duodenal specimens and for older animals. Conclusion and Clinical Importance The quality of histopathologic specimens obtained via SIEB is influenced by the fixation method. Additionally, other factors differ between dogs and cats. These results contribute to improved SIEB practices in veterinary medicine.