Given that the free radical scavenging capacity of stabilizers is closely associated with the conjugation degree of their molecular structures, this study designed and synthesized a series of fullerene-phenylpyrrolidine derivatives via the Prato reaction based on the regulation strategy of molecular conjugation effect, aiming to explore the regulatory mechanism of the side-chain conjugation effect of fullerene derivatives on their stabilizing performance. The stabilizing effects of these derivatives on nitrocellulose (NC) were systematically evaluated using the methyl violet test, vacuum stability test, and isothermal thermogravimetric analysis. The underlying mechanism was elucidated using electron spin resonance spectroscopy and theoretical calculations. The results indicate that all synthesized fullerene derivatives exhibit significant stabilizing effects on NC. Furthermore, as the number of benzene rings on the fullerene pyrrolidine unit increases, the molecular conjugation system progressively expands, leading to an enhanced stabilizing performance on NC, with all derivatives outperforming the traditional stabilizers DPA and C2. Mechanistic studies reveal that the expanded conjugation system enhances the delocalization of π-electrons, reducing the energy gap (ΔE) between the highest occupied molecular orbital and the lowest unoccupied molecular orbital. This alteration in electronic structure significantly improves the derivatives ability to capture nitrogen oxide radicals (NO·), thereby effectively inhibiting the autocatalytic decomposition of NC. This study firstly reveals the intrinsic relationship between side-chain conjugation strength and stabilizing efficiency of fullerene-based stabilizers, providing a novel strategy for the design of high-efficiency NC stabilizers by regulating the conjugation effect.

Filter patch analysis (FP) and membrane patch colorimetry (MPC) are widely used to assess lubricant degradation and varnish potential. Based on filtration principles, MPC, which uses finer cellulose nitrate membranes (0.45 µm) and solvent extraction, is often assumed to produce darker staining than FP performed on coarser membranes (0.8 µm). However, the opposite behavior is frequently observed in a subset of the mineral hydraulic oils investigated in this study, for which the choice of membrane material strongly affects the colorimetric response. By systematically comparing both methods using different membrane materials on in-service and laboratory-aged oils, this study shows that this inversion arises from membrane-oil chemical selectivity rather than from porosity or test configuration. Cellulose nitrate membranes used in MPC weakly retain certain oxidation-derived species, leading MPC to under-estimate varnish-related problems observed in the field. These results demonstrate that membrane material choice directly impacts varnish diagnostics and must be considered to avoid misinterpretation of lubricant degradation severity.

Unidirectional-flow assay strip fabricated via an integrated process for multiplex detection of inflammatory biomarkers.

ABSTRACT Blood grouping assays are commonly performed using tube tests or column agglutination, which require meticulous procedures by trained personnel. Paper‐based assays offer simplicity and readability; however, they are typically made with cellulose‐based mediums and demonstrate poor long‐term stability and low background to signal contrast. Although nitrocellulose (NC) membranes improve stability through higher protein adsorption, very few are manufactured with sufficiently large pore sizes that prevent the non‐specific retention of blood cells. This study presents two new NC membrane‐based assays, including an NC vertical flow‐through membrane not previously applied for blood grouping, and compares their performance and stability against two cellulose‐based papers commonly studied. Stability was investigated at 4°C and room temperature (RT) over a convenient 9‐month period. Anti‐A antibodies were tested following 1/2 to 1/16 dilution with natural saline solution (NSS, 0.9% NaCl), 5% bovine serum albumin (BSA) in NSS, or 5% sucrose in NSS. Assays were characterized according to blood spot signal intensity in comparison to negative controls. NC‐based assays demonstrated superior antibody stability compared to cellulose, with the vertical flow NC membrane showing the highest performance. All papers were more stable following 4°C storage. Furthermore, sucrose significantly improved stability at RT compared to BSA and NSS alone.

ABSTRACT In the pursuit of high-efficacy, low-visibility infrared illuminants, three distinct formulations were developed: I-1, composed of nitrocellulose (NC); I-2, containing glycidyl azide polymer (GAP); and I-3, a composite of NC and GAP. Among these, formulation I-3 demonstrated an exemplary equilibrium, achieving a burn duration of 62 seconds coupled with enhanced irradiance. Molecular dynamics simulations revealed that the rigid structure of nitrocellulose and the flexible chains of glycidyl azide polymer amalgamate to form a dense microarchitecture (with a free volume of 13.17% and a cohesive energy density of 464.0 J/cm³). This microstructural arrangement significantly contributes to improved combustion stability and radiative efficiency. This investigation offers essential mechanistic insights that advance the development of high-performance, low-signature pyrotechnics.

Ammonium dinitramide (ADN), a new-generation green high-energy oxidizer, faces application challenges due to its strong hygroscopicity and poor compatibility with polymer binders. This study proposes a double-shell structure with ADN as the core, graphene oxide (GO) as the intermediate layer, and a binder as the outer shell. Molecular dynamics simulations were performed to investigate composite systems using nitrocellulose (NC), cellulose acetate butyrate (CAB), polystyrene (PS), and their blends NC/CAB and NC/PS as binders. The results demonstrate that GO acts as a "molecular double-sided adhesive", significantly enhancing the interfacial interaction between ADN and the binders. The NC/PS blend binder exhibits the best overall performance, with the binding energy increased by 1.13 times. Analysis revealed that the NC/PS system establishes the strongest intermolecular interactions among ADN, GO, and the binder via mechanisms like π-π stacking and multiple hydrogen bonds. The glass transition temperature reaches 400.93 K, indicating excellent thermal stability and potential safety/reliability. Mechanical property analysis shows that the NC/PS composite system imparts a better comprehensive balance of stiffness, shear performance, and structural isotropy to the ADN-based polymer-bonded explosive (PBX). This research elucidates the enhancement mechanism of GO and the regulation principles of binders at the molecular scale, providing a theoretical foundation for designing high-performance energetic material.

Methods for determining elements contained in suspended particles of different sizes in atmospheric air by inductively coupled plasma mass spectrometry are proposed. Cascade impactors with sulfate cellulose filters with an average pore size of 15, 10, 5, 2.5, and 1 μm are recommended for the selection of aerosol particles (PM) with a size of >1 μm, as well as the quartz perfilters complete with nitrate cellulose filters with an average pore diameter of 0.2 μm with a paper base plate with coarse grain 500 g/m2 for the selection of particles with a size of <1 μm. The following requirements have been established for air sampling when monitoring maximum single concentrations: air flow values υd = 1.2 dm3/min, υf = 1.0 dm3/min, time of sampling tmin = 20 min for PM >1 μm, and υd = 2.0 dm3/min, υf = 1.8 dm3/min, tmin = 11 min for PM <1 μm. The effectiveness of the techniques in monitoring average daily concentrations has been proven. The developed analysis methods are used to determine the elemental composition of fractional dust of atmospheric air in the area of a metallurgical enterprise for the production of steel pipes. Based on the results of the research and metrological examination of materials for the development of measurement methods, their certification was carried out: the methods were included in the unified register of certified methods in the territory of the Russian Federation (MUK 4.1.4060-24 (FR.1.31.2023.45935); MUK 4.1.4159-25 (FR.1.31.2024.500365)). A new approach to the multiparametric analysis of atmospheric air is shown. A multiparametric analysis can be used to determine air pollution standards.

Industrially sole-phase magnetic powders for microwave absorption (MA) purposes rely mainly on magnetic loss, restricting better impedance matching. Concurrently, the massive disposal of single-use industrial products, such as medical diagnostics, presents a pressing environmental challenge. Herein, we introduce a cross-industrial strategy to transform waste nitrocellulose (NC) membranes from medical lateral flow assay (LFA) strips into functional MA materials via dimethyl sulfoxide (DMSO)-induced structural reconstruction. The dissolved NC transforms from a porous network into a condensed binding matrix, enabling the fabrication of two distinct product forms: (1) flexible, transparent, and magnetic Fe3O4/NC hybrid films, and (2) Fe3O4 aggregates bonded by NC. DMSO concentration was revealed as a factor regulating the microstructure and MA behavior of the NC-treated Fe3O4 aggregates. With improved impedance matching, the NC-treated Fe3O4 aggregates show good MA properties, e.g., a minimum reflection loss (RL) of −38.94 dB at 11.57 GHz (70 wt % filler/paraffin), −42.31 dB at 15.55 GHz (60 wt % filler/paraffin), and −47.02 dB at 6.54 GHz (50 wt % filler/paraffin). This work establishes a scalable strategy for designing MA materials from discarded medical resources.

ABSTRACT The pyrotechnic delay plays a critical role in providing a time interval between two successive explosive events in the explosive train. The delay composition is filled into a metal tube in the form of compressed powder, consisting of fuel, oxidizer, and binder. The Inverse burn rate (IBR, s/cm) of the delay composition is a determining factor that plays a vital role in providing delay time within a particular column length of the delay element. In the present study, an experimental investigation was conducted on the inverse burn rate of a B/BaCrO4/NC-based binary delay system by varying the stoichiometry (10/90), where boron serves as the fuel, barium chromate as the oxidizer, and nitrocellulose (NC) acts as the binder. The effect of stoichiometry on density, heat of reaction, particle size, crystallite size, and thermal conductivity of the composition, as well as the impact of these parameters on the inverse burn rate (IBR) and delay time of the binary delay composition, has been studied. The method for controlling all these parameters has been discussed. The effect of hardware and temperature conditioning on delay time was studied experimentally. Results revealed that, as the percentage of boron decreases and barium chromate increases, the heat of reaction and thermal conductivity of the composition decrease; the density, crystallite size and particle size of the composition increase. It is evident that these parameters significantly affect IBR and delay time. The B/BaCrO4/NC binary delay shows IBR ranging from (0.22–1.59 s/cm) with reliable burning and smooth propagation at all temperature conditions in different hardware. The composition supported combustion, having up to 3% boron and more than 10% boron, it becomes a flash composition. The B/BaCrO4/NC binary delay composition burns slower and produces more delay time in brass hardware as compared to aluminum hardware. The thermal conductivity of the hardware plays a critical role in achieving a tunable delay time within the specified column length of the delay tube. This research work is useful to tailor the IBR and to improve the consistency in the delay time of pyro devices.

Electrochemical demilitarization of solid composition B (HMX/RDX/TNT) and nitrocellulose

Abstract This work seeks to examine the catalytic role of porous carbon-supported nickel (C-Ni) composites in regulating the thermal decomposition properties of nitrocellulose (NC). Porous carbon (C) with a high specific surface area and its nickel supported composite (C-Ni) were successfully synthesized via the melting method combined with the hydrothermal method. Scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, and various other techniques were employed to characterize their morphology and structure. As shown by differential scanning calorimetry (DSC) findings, the addition of the C-Ni catalyst shifted the peak thermal decomposition temperature of NC upward by 0.6°C relative to pure NC. These findings demonstrate that the as-prepared C-Ni composites can effectively catalyze the thermal decomposition of NC, providing experimental evidence for the application of nanocarbon-based catalysts in energetic materials.

Self-driven microfluidic chip with integrated lateral and vertical flow assays for dual-readout point-of-care testing.

Photothermal vertical flow biosensors (VFBs) have emerged as attractive tools for biomarker detection, addressing restricted sensitivity, insufficient quantitative accuracy, and geometric mismatch issues of traditional photothermal lateral flow biosensors (LFBs) while retaining rapid detection capability. Herein, we developed a syringe-based wettability-enhanced photothermal vertical flow biosensor (SW-PVFB) for prostate-specific antigen (PSA) detection, integrating tantalum ditelluride (TaTe2) nanosheets as highly efficient photothermal probes and hydrophilic/hydrophobic patterned nitrocellulose (NC) membranes for precise fluid control and target enrichment. The 10-20-nm-thick TaTe2 nanosheets exhibited a photothermal conversion efficiency of 50.74% and good stability, efficiently converting near-infrared irradiation to detectable heat signals. The hydrophilic/hydrophobic NC membrane confined fluid flow to the detection zone, enhancing the TaTe2 accumulation and signal intensity. Under optimal conditions, SW-PVFB detected PSA in urine over 0-160 ng mL-1 with a limit of detection (LOD) of 0.028 ng mL-1, significantly outperforming conventional LFBs and standard VFBs. It showed high specificity against interfering proteins (e.g., CA9 and CEA), good reproducibility (RSD ≤ 3.8%), and recoveries of 89.1-112.7% in spiked urine. Integrated with a smartphone for portable signal readout, this SW-PVFB provides a sensitive, user-friendly point-of-care testing (POCT) platform for decentralized PSA diagnostics.

ABSTRACT Solid spheres composed of sub-micron CL-20/HMX co-crystal particles with nitrocellulose (NC) as a binder and structural framework were fabricated by droplet-confined crystallization. Optimal preparation conditions were established through single-factor experiments, which evaluated key parameters including the concentration of explosive solution and NC, the temperature of the explosive solution and non-solvent, and the drop height. NC, uniformly distributed, facilitates the aggregation of approximately 2 μm granular CL-20/HMX co-crystal particles into dense spherical structure with a diameter of about 1 mm. The solid spheres exhibit not only regular spherical morphology and uniform particle size distribution but also enhanced flowability and higher packing density compared to previously reported hollow spheres and flake-like co-crystals. Furthermore, the solid spheres show a reduced decomposition temperature and more rapid energy release, along with decreased friction sensitivity, improved ignition performance and pronounced self-sustaining combustion characteristics. This study demonstrates that the structure of energetic materials can influence their properties and also provides a new reference for the preparation of molding powders for press-loaded explosives.

Enhance the fracture toughness of RDX-based propellant: design of mussel-activated RDX surface functionalized coating

Bacillus cereus is a Gram-positive rod-shaped bacterium widely distributed in natural environments. Strains of this opportunistic pathogen can cause a range of illnesses, including bacteremia, food poisoning, localized infections, and severe systemic diseases, leading to substantial economic losses and adverse effects on related processing industries and livestock farming. Consequently, the establishment of a rapid detection method for Bacillus cereus is urgently needed to facilitate timely and effective prevention and control of this pathogen. In this study, polyclonal antibodies and colloidal gold solutions were prepared, followed by optimization of spray concentrations for the control line (C line) and test line (T line). Various types of nitrocellulose (NC) membranes were also evaluated. After assembly, the test strips were systematically assessed. The results indicate that the optimal detection was achieved when the antigen was labeled at 10 μg/mL, with the C line sprayed at 1 mg/mL and the T line at 0.5 mg/mL. Sartorius CN140 was identified as the most suitable NC membrane. The colloidal gold test strip showed no cross-reactivity with Bacillus thuringiensis, Bacillus mycoides, Bacillus subtilis, Bacillus licheniformis, Staphylococcus aureus, or Escherichia coli. Validation experiments confirmed that the test strips exhibited high sensitivity, specificity, and stability. When challenged with closely related species and other genera, the immunochromatographic strip demonstrated excellent specificity and sensitivity, offering a reliable tool for rapid clinical detection of Bacillus cereus infections.

To avoid dependence on conventional raw materials, global emphasis has been placed on obtaining alternative plant celluloses and the chemical synthesis of cellulose. The use of synthetically derived cellulose as a precursor for cellulose nitrates (NCs) is currently absent in global practice, which underscores the undoubted relevance of this research. Cellulose nitrate (NC) was synthesized in a 138% actual yield by nitration of synthetic cellulose (SC)—a new type of cellulose—prepared by electropolymerization from an aqueous glucose solution in the presence of catalytic tungsten–vanadium heteropolyacid of the 1–12 series with the chemical formula H6[PW10V2O40]: a nitrogen content of 11.83%, a viscosity of 198 mPa·s, a high solubility of 91% in an alcohol–ether solvent, and an ash content of 0.05%. SEM provided a general concept of the morphological structure of SC and SC-derived NC. The initial SC consisted of flat, curly fibers with a smooth surface approximately 10–20 μm wide, with no aggregation observed. The fibers of SC-derived NC had a cylindrical shape with a diameter of up to 25 μm and a rough surface. FT-IR spectroscopy revealed that SC and SC-derived NC have the main functional groups characteristic of classical cellulose (3346, 2901, 1644, 1429, 1162, and 1112 cm−1) and nitrate esters of cellulose (1650, 1278, 832, 747, and 689 cm−1), respectively. For the first time, a full-profile analysis discovered that SC is made up of the monoclinic phase of cellulose Iβ with an antiparallel chain arrangement. SC with a crystallinity index (CrI) of 81–86% was shown to undergo amorphization upon nitration, with the CrI declining to 17% and the crystallite sizes decreasing from 44 × 62 × 59 × 94 Å to 29 × 62 × 26 × 38 Å. Coupled TGA/DTA revealed that SC exhibits a high-temperature endothermic peak of decomposition of 374 °C, with a weight loss of 84%. The thermostable SC-derived NC exhibits a high onset temperature of intense decomposition of 200 °C and an exothermic peak of 208 °C, with a weight loss of 88%, and is characterized by a high specific heat of decomposition of 7.74 kJ/g. This study provides new insights into the functionalization of SC with a high degree of polymerization, expanding the classical concepts of cellulose nitration.

Lateral-flow immunoassays (LFIAs) are increasingly used as diagnostic tools for point-of-care testing because of their speed, simplicity, and cost-effectiveness. However, traditional antibody immobilization techniques, which primarily rely on the passive antibody adsorption onto nitrocellulose (NC) membranes, have notable limitations. Accordingly, we developed an innovative LFIA platform that integrates recombinant rabbit single-chain variable fragments (scFvs) genetically fused with NC-binding proteins (NBPs) to enhance immobilization and overall performance. Twenty-one candidate proteins were screened, of which lactoferrin emerged as a superior NBP because of its robust and stable adsorption onto NC membranes, even in the presence of surfactants. Fusion constructs of scFvs and lactoferrin (LF) (designated scFv-LF) were constructed and expressed in ExpiCHO cells. The purified scFv-LF proteins maintained high antigen-binding activity across a wide pH range (2-13) and exhibited improved performance in dot blot assays, enzyme-linked immunosorbent assay (ELISA), and lateral flow formats compared to scFvs alone. A complementarity-determining region (CDR)-grafting strategy was used to produce scFv-LF variants with modified regions that retained the C2R framework. C1R/C2R and B1R/C2R fusion proteins demonstrated enhanced antigen activity and high signal intensities. B1R/C2R scFv-LF fusion achieved a 100-fold lower detection limit for influenza B nucleocapsid protein than its nonfused counterpart. Overall, the scFv-LF fusion platform is a powerful solution for achieving stable and oriented antibody immobilization on NC membranes, substantially enhancing the sensitivity and reproducibility of LFIA systems. This modular approach facilitates the rapid customization of a diverse range of antigens through CDR grafting, paving the way for next-generation diagnostic developments.

Multiscale simulation of effects of nitroglycerin plasticizer on morphology and mechanical properties of nitrocellulose-based propellants

Preliminary study of indoor radon, thoron and their progeny in Bijnor and nearby places, U.P., India.