Counter Collision Research Articles

Assessing cytotoxicity and biocompatibility of cellulose nanofibrils on alveolar macrophages

Cellulose nanofibrils (CNFs) are a promising new material derived from biomass, known for their lightweight, high strength, and low thermal expansion properties. However, concerns have been raised about their potential health impact due to their fibrous and ultrafine nature. This study aimed to evaluate the effects of different types of CNFs on rat alveolar macrophages (NR8383). The CNFs tested included TEMPO-oxidized CNFs (CNF1), phosphorylated CNFs (CNF2), mechanically fibrillated CNFs from softwood bleached kraft pulp (CNF3), CNFs derived from citrus peels (CNF4), and two size fractions (coarse and ultrafine) of softwood bleached kraft pulp obtained by aqueous counter collision processing (CNF5 and CNF6). The findings showed no significant production of reactive oxygen species in any of the CNF exposure groups. However, exposure to CNF1, CNF2, and CNF3 led to increased mitochondrial dehydrogenase activity, elevated pro-inflammatory cytokine production, and upregulation of inflammation-related genes. These effects were less pronounced in the CNF4, CNF5, and CNF6 groups. Cellular uptake of CNFs was observed across all groups, and the response to CNF exposure differed from the response to microcrystalline cellulose, which was used as a reference material. No clear correlation was found between the observed effects and the presence of biological contaminants, such as bacteria and endotoxins, in the CNF dispersions. These findings suggest that CNFs may either activate macrophages or demonstrate biocompatibility rather than cytotoxicity. The impact and biocompatibility of CNFs on alveolar macrophages appear to be influenced by various factors, including the source of the CNF raw material, the manufacturing process, physicochemical properties, and biological characteristics of the CNF dispersion. This study provides valuable insights into the potential inhalation effects of CNFs.Graphic abstract

Emergence of Amphiphilicity on Surfaces of Pure Cellulose Nanofibrils Directly Generated by Aqueous Counter Collision Process.

The present paper describes a downsizing mechanism of an aqueous counter collision (ACC) process that enables the rapid preparation of cellulose nanofibrils (CNFs) as an aqueous dispersion solely by impinging a pair of water jets containing the raw materials. Extensive studies have revealed that the resulting CNFs by ACC have amphiphilic fiber surfaces, in which two kinds of faces with different natures are present along the entire fiber axis. They therefore have superior adsorption to surfaces of various conventional polymer plastics. These characteristic adsorption behaviors, which are totally different from those for other CNFs prepared by other means, are attributable to their hydrophobic surfaces. In the present study, high-resolution microscopy, including atomic force microscopy, confocal laser scanning microscopy, and scanning electron microscopy with broad argon ion beam milling, was used to determine how the emergence of such hydrophobic characteristics in a nanofibril face occurs in relation to the ACC nanopulverization mechanism due to the collision of the pair of water jets.

Hard X-ray inverse Compton scattering at photon energy of 87.5 keV

Production of hard X-ray via inverse Compton scattering at photon energies below 100 keV range aimed at potential applications in medicine and material research is reported. Experiments have been performed at the Brookhaven National Laboratory, Accelerator Test Facility, employing the counter collision of a 70 MeV, 0.3 nC electron beam with a near infra-red Nd: YAG laser (1064 nm wavelength) pulse containing ~ 100 mJ in a single shot basis. The radiation distribution of the scattered photon beam is assessed to be sufficiently quasi monochromatic to produce clear contrast from the Au K- edge at 80.7 keV.

Nanotechnology Applied to Cellulosic Materials.

In recent years, nanocellulosic materials have attracted special attention because of their performance in different advanced applications, biodegradability, availability, and biocompatibility. Nanocellulosic materials can assume three distinct morphologies, including cellulose nanocrystals (CNC), cellulose nanofibers (CNF), and bacterial cellulose (BC). This review consists of two main parts related to obtaining and applying nanocelluloses in advanced materials. In the first part, the mechanical, chemical, and enzymatic treatments necessary for the production of nanocelluloses are discussed. Among chemical pretreatments, the most common approaches are described, such as acid- and alkali-catalyzed organosolvation, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, ammonium persulfate (APS) and sodium persulfate (SPS) oxidative treatments, ozone, extraction with ionic liquids, and acid hydrolysis. As for mechanical/physical treatments, methods reviewed include refining, high-pressure homogenization, microfluidization, grinding, cryogenic crushing, steam blasting, ultrasound, extrusion, aqueous counter collision, and electrospinning. The application of nanocellulose focused, in particular, on triboelectric nanogenerators (TENGs) with CNC, CNF, and BC. With the development of TENGs, an unparalleled revolution is expected; there will be self-powered sensors, wearable and implantable electronic components, and a series of other innovative applications. In the future new era of TENGs, nanocellulose will certainly be a promising material in their constitution.

테일러-쿠테 유동 및 유체충돌 분쇄시스템을 이용한 α -키토산 나노섬유 제조

테일러-쿠테 유동 및 유체충돌 분쇄시스템을 이용한 α -키토산 나노섬유 제조

Cellulose Nanofibrils Pulverized from Biomass Resources: Past, Present, and Future Perspectives

Advances in nanotechnology have changed conventional concepts in materials science. This has aloso strongly influenced natural biomass products with hierarchically built-up structures. In general, hierarchical structures in bio-based materials are built up by molecular self-assembly, followed by nanoassembly to form higher-level structures. Key to each step is the formation of interactions at each individual scale. Nature usually achieves such fabrication through a bottom-up process. However, fabrication can also be achieved through a top-down process, with various such downsizing methods now in development. This review article aims to describe trends in nanofiber technology among downsizing processes applied to cellulose as a representative biomass, ranging from fundamentals to recent techniques. The advantages of our recently developed technique, nanopulverization by aqueous counter collision, are also discussed. This method successfully decomposes interactions selectively without damaging the molecular structure, finally liberating components of various sizes into water to provide a transparent and homogeneous component–water system. As nanocellulose research is a broad area involving various fields, the cited references are limited to the scope of the author’s knowledge.

Optically transparent, ultra-tough, aerosol-sprayable, waterborne polyurethane composite reinforced with natural polymer nanofibers

In this study, we introduce an optically transparent, mechanically tough waterborne polyurethane (WPU) nanocomposite incorporating succinylated cellulose nanofibers (SCNF) and chitin nanofibers (SChNF) as the reinforcing fillers. Both a commercially available WPU as well as a typical anionic WPU synthesized using poly(tetrahydrofuran) (PTMEG), isophorone diisocyanate (IPDI), and dimethylol propionic acid (DMPA) as the internal emulsifier are used. Aqueous colloidal suspensions of the SC(h)NF nanofillers are prepared via the aqueous counter collision (ACC) method. A simple blending of the two waterborne materials renders homogeneous WPU/SC(h)NF (1–10 wt%) nanocomposite that simultaneously achieve an outstanding mechanical toughness and high optical transparency (>90%). We also demonstrate an environmentally benign aerosol-spray coating of the WPU/SC(h)NF using dimethyl ether (DME) as the aerosol propellant.

Emerging Food Packaging Applications of Cellulose Nanocomposites: A Review.

Cellulose is the most abundant biopolymer on Earth, which is synthesized by plants, bacteria, and animals, with source-dependent properties. Cellulose containing β-1,4-linked D-glucoses further assembles into hierarchical structures in microfibrils, which can be processed to nanocellulose with length or width in the nanoscale after a variety of pretreatments including enzymatic hydrolysis, TEMPO-oxidation, and carboxymethylation. Nanocellulose can be mainly categorized into cellulose nanocrystal (CNC) produced by acid hydrolysis, cellulose nanofibrils (CNF) prepared by refining, homogenization, microfluidization, sonification, ball milling, and the aqueous counter collision (ACC) method, and bacterial cellulose (BC) biosynthesized by the Acetobacter species. Due to nontoxicity, good biodegradability and biocompatibility, high aspect ratio, low thermal expansion coefficient, excellent mechanical strength, and unique optical properties, nanocellulose is utilized to develop various cellulose nanocomposites through solution casting, Layer-by-Layer (LBL) assembly, extrusion, coating, gel-forming, spray drying, electrostatic spinning, adsorption, nanoemulsion, and other techniques, and has been widely used as food packaging material with excellent barrier and mechanical properties, antibacterial activity, and stimuli-responsive performance to improve the food quality and shelf life. Under the driving force of the increasing green food packaging market, nanocellulose production has gradually developed from lab-scale to pilot- or even industrial-scale, mainly in Europe, Africa, and Asia, though developing cost-effective preparation techniques and precisely tuning the physicochemical properties are key to the commercialization. We expect this review to summarise the recent literature in the nanocellulose-based food packaging field and provide the readers with the state-of-the-art of this research area.

Blunt abdominal trauma patients presenting to a tertiary care facility of Pakistan: A three years' experience.

Blunt abdominal trauma (BAT) refers to injuries without wounds entering the peritoneal cavity due to road traffic accidents (RTA) and falls, as a result of collision or counter collision. The objective of the present study was to determine the frequency of patients with visceral injuries in blunt abdominal trauma. This study was carried out in the Department of Surgery, including ward-3 of Jinnah Post Graduate Medical Centre, Karachi, from November 2017 till November 2020. The study design was descriptive case series. During the study period, the data of 112 patients was collected, which comprised of 102 males and 10 females. All the patients between 12 to 65 years of age (mean age:31.84±13.14 years) presenting to the emergency with < 24 hours of abdominal trauma, were included in the study. Organs involved during blunt abdominal trauma were observed and frequency was recorded. Liver injuries were found in 48(42.28%) patients, intestinal injuries in 40(35.7%), splenic injuries in 32(28.5%), kidney injuries in 24(21.4%), pancreatic injuries in 8(7.1%) and stomach injuries in 4(3.5%) patients. Grade 4 liver injury was found in 80(71%) patients, Grade 2 and 3 splenic injuries in 56(50%) patients whereas 47(42%) patients had grade 1 kidney injury. Liver was found to be the most frequent organ involved, followed by intestine and spleen.

Preparation of carbon nanoparticles from activated carbon by aqueous counter collision

In the present study, crystalline cellulose biomass material was converted into carbon nanoparticles via carbonization to activated carbon with micropores of various sizes. This was subsequently subjected to aqueous counter collision (ACC) to produce hydrophobic porous functional particles. Initially, raw crystalline cellulose material was carbonized into activated carbon materials with various pore distributions prior to ACC. Pore distribution depended on the activation time, and was confirmed by nitrogen (N2) adsorption isotherms. The surface areas and pore volumes of carbon activated for 8 h were larger than those of carbon activated for 2 h. When they were subjected to ACC, the width and length of the carbon particles decreased as the number of pulverizing cycles during the ACC treatment increased. Eventually, carbon nanoparticles of 70 nm width that had improved dispersibility and stability were produced. The diameters of the carbon nanoparticles and their dispersibility were dependent on the pore distribution and surface areas of the activated carbon subjected to the ACC treatment. The ACC process facilitated the preparation of carbon nanoparticles from activated carbon derived from biomass, and is, therefore, an important strategy for the sustainable production of a sought-after and valuable resource.

Alkali-activation of cellulose nanofibrils to facilitate surface chemical modification under aqueous conditions

In this study, we developed a surface-activation technique for cellulose nanofibrils (CNFs) using mild-alkali and aqueous conditions. CNFs were initially processed using the aqueous counter collision (ACC) method to produce Janus-type amphiphilic CNFs with both hydrophilic and hydrophobic faces on the surface of a single nanofibril (ACC-CNF). Selective functionalization of the hydroxy groups on the hydrophilic faces creates an opportunity to develop novel nano-building blocks that introduce heterogeneous and tailored surface characteristics into the design of nanomaterials. In this study, alkaline conditions were used to activate the hydroxy groups on the surface of ACC-CNFs as a pre-treatment for the partial crystalline transformation from cellulose I to cellulose II. We found that alkali treatment with sodium hydroxide (NaOH) solutions (concentration range 1–7 wt%) did not fully transform the structure of ACC-CNFs into cellulose II, nor change the morphology of nanofibrils, as seen from their wide-angle X-ray diffraction patterns and atomic force microscopy images. We also found that the hydroxy groups at the surface region of the ACC-CNFs were sufficiently reactive under the moderate alkali and aqueous conditions to undergo subsequent carboxymethylation. Therefore, alkali treatment of ACC-CNFs with a 1–7 wt% NaOH solution rendered the surface of the ACC-CNFs as sufficiently reactive for chemical modification without morphological changes. This simple method for surface activation of CNFs can be useful in the development of future sustainable and novel materials for a variety of applications.

Characterization of mercerized cellulose nanofibrils prepared by aqueous counter collision process

Cellulose nanofibrils (CNFs) obtained by aqueous counter collision (ACC) methods have amphiphilic Janus-type properties, which appear markedly for ACC–CNFs prepared from bacterial nanocellulose (BNC) pellicles. The amphiphilic Janus-type surface is exposed because of the mechanism involved in ACC pulverizing of cellulose materials, in which the predominant interactions of the (2 0 0) lattice plane of the cellulose I crystal structure are weak interplanar van der Waals interactions. Such selective cleavage is more likely to occur for highly crystalline BNC. This study focused on alkali-mercerized cellulose samples, which are of lower crystallinity than BNC. The mercerized raw materials were subjected to ACC treatments and their fiber morphologies, crystallinities, and surface properties were compared to those of ACC–CNFs from native samples. In particular, the Wide-angle X-ray diffraction (WAXD) results suggested that the cleavage was most likely to occur at the (1 1 0) plane in nanofibrils derived from cellulose II, unlike (2 0 0) lattice plane for the case of cellulose I. Accordingly, the entire results indicate that the properties of the ACC-treated mercerized CNFs differ greatly from those of conventional ACC–CNFs composed of cellulose I crystalline structure. This is presumably because ACC nanopulverization proceeds depending on the surface structure and crystalline morphology of the raw material.

Characteristics of Bamboo- and Wood-derived Cellulose Nanofibrils Produced by Aqueous Counter Collision

Characteristics of Bamboo- and Wood-derived Cellulose Nanofibrils Produced by Aqueous Counter Collision

Adsorption of Janus-Type Amphiphilic Cellulose Nanofibrils onto Microspheres of Semicrystalline Polymers

Cellulose nanofibrils (CNFs), which are attracting increasing attention as sustainable biomass nano-objects, are believed to be hydrophilic. Recently, aqueous counter collision (ACC) has been used to produce Janus-type amphiphilic cellulose nanofibrils (ACC-CNFs) from various cellulosic raw materials. In the current study, ACC-CNFs were preferentially adsorbed onto hydrophobic isotactic polypropylene (i-PP) microparticles and linear low-density polyethylene (LLDPE), which demonstrated their characteristic amphiphilicity. This was achieved by simply mixing the constituents together in aqueous media. The products were visualized by confocal laser microscopy (CLMS). Thermodynamic measurements obtained by differential scanning calorimetry revealed that the melting points of i-PP/ACC-CNFs and LLDPE/ACC-CNFs were lower than those of the untreated polymers, which indicates interactions between the ACC-CNFs and the polymer surfaces. Coating the polymer particles with the ACC-CNFs—as confirmed by CLMS—appeared to reduce their melting points. This finding demonstrates the possibility of a novel fusion between synthetic polymeric materials and biomass nano-objects.

Emulsifying Properties of &lt;i&gt;α&lt;/i&gt;-Chitin Nanofibrils Prepared by Aqueous Counter Collision

Emulsifying Properties of &lt;i&gt;α&lt;/i&gt;-Chitin Nanofibrils Prepared by Aqueous Counter Collision

Environment-Friendly Zinc Oxide Nanorods-Grown Cellulose Nanofiber Nanocomposite and Its Electromechanical and UV Sensing Behaviors.

This paper reports a genuine environment-friendly hybrid nanocomposite made by growing zinc oxide (ZnO) nanorods on cellulose nanofiber (CNF) film. The nanocomposite preparation, characterizations, electromechanical property, and ultraviolet (UV) sensing performance are explained. CNF was extracted from the pulp by combining the 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) oxidation and the aqueous counter collision (ACC) methods. The CNF film was fabricated using doctor blade casting, and ZnO nanorods were grown on the CNF film by seeding and by a hydrothermal method. Morphologies, optical transparency, mechanical and electromechanical properties, and UV sensing properties were examined. The nanocomposite’s optical transparency was more than 80%, and the piezoelectric charge constant d31 was 200 times larger than the CNF film. The UV sensing performance of the prepared ZnO-CNF nanocomposites was tested in terms of ZnO concentration, UV irradiance intensity, exposure side, and electrode materials. A large aspect ratio of ZnO nanorods and a work function gap between ZnO nanorods and the electrode material are essential for improving the UV sensing performance. However, these conditions should be compromised with transparency. The use of CNF for ZnO-cellulose hybrid nanocomposite is beneficial not only for electromechanical and UV sensing properties but also for high mechanical properties, renewability, biocompatibility, flexibility, non-toxicity, and transparency.

Characterization of dual nano-size effects of ACC-cellulose nanofibrils on crystallization behavior of hydrophilic poly(vinyl alcohol)

This study attempts to clarify thermodynamic quantification on interaction between poly(vinyl alcohol) (PVA) and wood-derived cellulose nanofibrils (CNFs) obtained by aqueous counter collision (ACC) method. Aqueous mixtures of PVA/ACC-CNFs with various fiber widths were cast as the target materials. The interfacial interactions between the two components were characterized through thermodynamic evaluation of the crystalline PVA component as a probe in the cast mixture. As the result, surface properties of the ACC-CNFs found to reflect on the crystallization behavior of the interacted PVA component, resulting in dual nano-size effects of either diluent or nucleating agent. Melting point depression behaviors of the PVA component indicated that ACC-CNFs with thinner widths induced nucleation effects on PVA crystallization, whereas ACC-CNFs with ca. 100 nm in width encouraged diluent effects on PVA components. It is noted that this trend found to be reverse to the case for PVA/ACC-CNFs of bacterial nanocellulose previously reported.

Study of Postdetonation Waves after the Counter Collision of Detonation Waves in a Bubble Liquid

Study of Postdetonation Waves after the Counter Collision of Detonation Waves in a Bubble Liquid

Localized surface acetylation of aqueous counter collision cellulose nanofibrils using a Pickering emulsion as an interfacial reaction platform

The self-organization of nano-sized fibrous building blocks is essential for the construction of biomimetic architectonics and hierarchically constructed bio-based materials. The localization of hydrophobic moieties on the surfaces of such nanofibrils is key to hierarchical assembly in aqueous systems. In this study, unique self-assembling fibrous building blocks comprising amphiphilic cellulose nanofibrils (CNFs) were prepared by aqueous counter collision (ACC). The purpose of the study was to control the surface properties of ACC-CNFs by selectively acetylating their surfaces at the oil/water interfaces of a Pickering emulsion. Localized interfacial reactions occurred when the ACC-CNFs were adsorbed onto the surfaces of oil droplets containing the reaction reagents. Such acetylation reactions were achieved whilst maintaining the crystallinity and fibrous morphology of the original CNFs. The surfaces of films cast from the acetylated ACC-CNFs described herein had unique self-aggregation properties that contrasted markedly with those of films cast from acetylated ACC-CNFs prepared in homogenous dispersions.

Facile size evaluation of cellulose nanofibrils adsorbed on polypropylene substrates using fluorescence microscopy

The current study proposes a facile method based on fluorescence microscopy (FM) for evaluating the size of cellulose nanofibrils (CNFs) prepared by aqueous counter collision (ACC). Prior to FM, a polypropylene film substrate was employed for the absorption and fixing of CNFs. Using FM, it is possible to detect a single ACC-CNF that is longer than 2 µm by staining with a fluorescent probe for cellulose (i.e., Calcofluor White). Comparison between FM and field emission scanning electron microscopy (FE-SEM) indicated that the lengths of the ACC-CNFs estimated from the FM images were in good agreement with the lengths from FE-SEM, although it was necessary for the ACC-CNFs to be over 20 nm in width for the FM. The full width at half maximum of the fluorescent intensity in the fluorescent images of ACC-CNFs correlated with the real widths obtained using FE-SEM, indicating that the current FM method also enables estimation of the widths of the CNFs using a regression line as a correction formula. Eventually this facile fluorescence microscopy technique could simultaneously provide reasonable size information with regard to both the lengths and widths of CNFs having over 20 nm in width and 2 µm in length with high aspect ratios over 100.