Enhanced Absorption Properties Research Articles

Biochar derived from biogas fermentation residue with enhanced absorption property suitable for efficient absorption of methylene blue in aqueous

Biochar derived from biogas fermentation residue with enhanced absorption property suitable for efficient absorption of methylene blue in aqueous

Preparation and Evaluation of the In situ Gel-forming Chitosan Hydrogels for Nasal Delivery of Morphine in a Single Unit dose in Rats to Enhance the Analgesic Responses.

In this study, an in situ gel-forming chitosan hydrogel was prepared with the use of glutamate salt of chitosan (Ch-Ga), β-glycerophosphate (Gp), and morphine (Mor). The paper is focused on in vitro physicochemical properties and in-vivo analgesic effects of the prepared chitosan hydrogel. The thermosensitive properties of prepared chitosan hydrogel were evaluated during the different temperatures and times. The physicochemical properties of chitosan hydrogel were investigated by infrared (IR) spectroscopy and X-ray diffraction analysis (XRD). Also, its cell cytotoxicity effects were evaluated in murine NIH/3T3 normal cells. Subsequently, the distribution of chitosan hydrogel in the nasal cavity of rats and its analgesic responses were evaluated. The prepared chitosan hydrogel showed that it could be gelled at the temperature of 34 °C before leaving the nose in the shortest possible time of 30 s. The analgesic responses of the intranasal (IN) injection of chitosan hydrogel (IN-chitosan hydrogel, 10 mg Mor/kg) in a single unit dose in rat relative to the placebo and intranasal or intraperitoneal (IP) injection of free morphine solution (IN-Free Mor or IP-Free Mor, 10 mg Mor/kg) via the hot plate test, reveal that the IN-chitosan hydrogel could induce fast analgesic effects of morphine with maximum possible effect (MPE) of 93% after 5 min compare to the IN-Free Mor and IP-Free Mor with MPE of 80% after 15 min and 66% after 30 min, respectively. Also, prolonged analgesic effects with MPE of 78 % after 6 h of injection were only seen in the IN-chitosan hydrogel injected group. The obtained fluorescent images of rat's brain injected with IN-chitosan hydrogel containing doxorubicine (Dox) as a fluorescent agent showed that the mucosal adhesive and absorption enhancer properties of IN-chitosan hydrogel resulting in longer presence of them in the nasal cavity of rats followed by more absorption of Dox from the blood vessels of olfactory bulbs with a 74% color intensity compared to the IN-Free Mor and IN-Free Dox with 15%. These data reveal that the IN-chitosan hydrogel could induce fast and prolonged analgesic effects of morphine compare to the IN/IP-Free Mor, which could be considered as an in situ gel-forming thermosensitive chitosan hydrogel for nasal delivery of wide ranges of therapeutic agents.

Absorption frequency band switchable intelligent electromagnetic wave absorbing carbon composite by cobalt confined catalysis

The dielectric loss of carbon materials is closely related to the microstructure and the degree of crystallization, and the microstructure modulation of electromagnetic wave absorbing carbon materials is the key to enhancing absorption properties. In this work, a porous elastic Co@CNF-PDMS composite was prepared by freeze-drying and confined catalysis. The graphitization degree and conductivity loss of carbon nanofibers (CNFs) were regulated by heat treatment temperature and Co catalyst content. The construction of a heterointerface between Co and C enhances the interfacial polarization loss. The Co@CNF-PDMS composite with 4.5 mm achieves the minimum reflection loss (RLmin) of –81.0 dB at 9.9 GHz and RL no higher than –12.1 dB in the whole of the X-band. After applying a load of up to 40 % strain and 100 cycles to Co@CNF-PDMS, the dielectric properties of the composite remain stable. With the increase of compression strain, the distribution density of the absorbent increases, and the CNF sheet layer extrusion contact forms a conductive path, which leads to the conductive loss increase, finally, the absorption band moves to a high frequency. The absorption band can be bi-directionally regulated by loading and strain with good stability, which provides a new strategy for the development of intelligent electromagnetic wave absorbing materials.

Lan+1NinO3n+1 (n = 1, 2, 3) RP-phases for EMI shielding and ESD applications

Advancements in electronics and digitization have led to concerns about electromagnetic interference (EMI), necessitating effective EMI shielding measures. This study investigates the electromagnetic wave absorption properties of Lan+1NinO3n+1 (n = 1, 2, 3) Ruddlesden-popper (RP) phases. While a single phase, La2NiO4, was obtained for n = 1, mixed phases of La3N2O7-δ/La4Ni3O10-δ were observed for n = 2 and 3. Electron paramagnetic resonance spectroscopy revealed superparamagnetic behavior for La2NiO4 and multi-resonance peaks for La3Ni2O7-δ, suggesting increased surface defects. La3Ni2O7-δ exhibited enhanced absorption properties, with a minimum reflection loss of −19.4 dB and a broader (less than −10 dB) bandwidth covering 4.2 GHz (X-band) at a thickness of 1.4 mm, attributed to optimal conductivity, magnetic resonance, eddy current losses, and synergistic dielectric loss. The sample with n = 2 demonstrates potential for EMI absorption and electrostatic discharge (ESD) applications.

Electron, hole and radical competition mechanism of layered porous g-C3N4 for hydrogen generation and organic pollutant degradation

Halogen doping is an effective approach to regulate the electronic structure and improve photocatalytic properties of g-C3N4. Here, a salt-assisted approach was employed to prepare layered porous halogen-doped g-C3N4. The effects of halogen electronegativity and pore morphology were discussed. Highly electronegative F-doped g-C3N4 with smaller pore size and higher surface area displayed the enhanced absorption property on reactants. The H2 production rate decreased and the RhB degradation significantly increased with increasing the electronegativity of layered porous g-C3N4, which was significantly different from the conventional halogen-doped g-C3N4 prepared with halogenated acid and monolayer g-C3N4. The decreased H2 evolution can be ascribed to the strong adsorption property, and the strong interactions between halide ions and H+ were difficult to be disassociated. Additionally, the RhB degradation performance of halogen-doped g-C3N4 significantly increased with increasing the electronegativity. The most active species that dominated the RhB degradation of F-doped g-C3N4 are leaved holes (h+), which are totally different from that of the pristine g-C3N4 and Cl/Br-doped g-C3N4 (superoxide radicals,·O2–). This work helps us to well understand the role and importance of electronegativity and pore morphology on the H2 generation and RhB degradation properties of layered porous g-C3N4.

Frequency tunable Ni–Ti‐substituted Ba–M hexaferrite for efficient electromagnetic wave absorption in 8.2–75 GHz range

The development of 5G telecommunication technology has seen a high demand for effective electromagnetic (EM) wave absorbers in the millimeter wave (mmWave) band. Because hexagonal M‐type ferrite is known to have high ferromagnetic resonance (FMR) in the 5G band frequency, it has attracted significant attention as a mmWave absorber. However, study of the relationship between magnetocrystalline anisotropy, FMR frequency, and EM wave absorption performance in the mmWave band remains insufficient. In this study, Ni–Ti‐substituted M‐type barium ferrite (Ba–M ferrite) was synthesized using the citrate sol–gel method, and the change in the magnetic properties caused by Ni–Ti substitution was analyzed. The complex permittivity, permeability, and reflection loss (RL) of the Ni–Ti‐substituted Ba–M ferrite composites in the 8.2–75 GHz broadband frequency range were also studied. The EM wave absorption frequency, which is governed by the FMR frequency, could be tuned by controlling the amount of substituted Ni–Ti ions in the Ba–M ferrite. The prepared EM wave absorber exhibited excellent EM wave absorption properties with an RL of −52 dB at 29.5 GHz and a matching thickness of 0.95 mm. This study provides insights into a frequency‐tunable EM wave absorber with enhanced absorption properties, attained by changing the magnetic properties of Ni–Ti‐substituted M‐type hexaferrites in the mmWave frequency band.

The Comparison of Titanium Dioxide and Zinc Oxide Used in Sunscreen Based on Their Enhanced Absorption

Nanomaterials have become increasingly popular in the cosmetic industry, especially in sunscreen production. These tiny particles can improve the performance of sunscreen products by enhancing their capacity to reflect and absorb ultraviolet (UV) radiation. This paper introduces two typical metal oxide nanoparticles (NPs), TiO2 NPs and ZnO NPs, in sunscreen and cosmetic products. Because of their propensity to absorb and deflect harmful UV radiation, they are frequently utilised. However, there is rising worry regarding the safe use of nanoparticles in these products especially the potential negative impact on human health. Moreover, the environmental risks associated with them, particularly in terms of their enhanced absorption properties also make their use an ongoing debate. In fact, studies have suggested that while they can result in more effective sun protection, they may also lead to unintended consequences. This paper also compares their sun protection effects, environmental impacts and health risks. It is crucial for customers to weigh the benefits and risks of nanomaterials in cosmetics and for both manufacturers and governments to adopt appropriate and detailed measures to ensure their safe and responsible use.

Preparation of mucoadhesive methacrylated chitosan nanoparticles for delivery of ciprofloxacin

Mucoadhesive polymers and their nanoparticles have attracted a lot of attention in pharmaceutical applications, especially transmucosal drug delivery (TDD). Mucoadhesive polysaccharide-based nanoparticles, particularly chitosan, and its derivatives, are widely used for TDD owing to their outstanding features such as biocompatibility, mucoadhesive, and absorption-enhancing properties. Herein, this study aimed to design potential mucoadhesive nanoparticles for the delivery of ciprofloxacin based on methacrylated chitosan (MeCHI) using the ionic gelation method in the presence of sodium tripolyphosphate (TPP) and compared them with the unmodified chitosan nanoparticles. In this study, different experimental conditions including the polymer to TPP mass ratios, NaCl, and TPP concentration were changed to achieve unmodified and MeCHI nanoparticles with the smallest particle size and lowest polydispersity index. At 4:1 polymer /TPP mass ratio, both chitosan and MeCHI nanoparticles had the smallest size (133 ± 5 nm and 206 ± 9 nm, respectively). MeCHI nanoparticles were generally larger and slightly more polydisperse than the unmodified chitosan nanoparticles. Ciprofloxacin-loaded MeCHI nanoparticles had the highest encapsulation efficiency (69 ± 13 %) at 4:1 MeCHI /TPP mass ratio and 0.5 mg/mL TPP, but similar encapsulation efficiency to that of their chitosan counterpart at 1 mg/mL TPP. They also provided a more sustained and slower drug release compared to their chitosan counterpart. Additionally, the mucoadhesion (retention) study on sheep abomasum mucosa showed that ciprofloxacin-loaded MeCHI nanoparticles with optimized TPP concentration had better retention than the unmodified chitosan counterpart. The percentage of the remained ciprofloxacin-loaded MeCHI and chitosan nanoparticles on the mucosal surface was 96 % and 88 %, respectively. Therefore, MeCHI nanoparticles have an excellent potential for applications in drug delivery.

Novel radar absorbing material using resistive frequency selective surface based polymer composites for enhanced broadband microwave absorption

In this paper, a novel approach using glass fibre laminate composite (GFLC) with nanoparticle embedded nanofibres and frequency selective surfaces (FSS) for improved electromagnetic (EM) wave absorption has been proposed. For enhanced absorption, the FSS was coated with polyvinylidene fluoride (PVDF) mixed with multi-walled carbon nanotubes (MWCNTs). The coatings were prepared through electrospinning technique. The composite prepared from FSS, PVDF-MWCNT layers and GFLC showed enhanced absorption properties. It was demonstrated that the fabricated composites reduced reflection of electromagnetic waves by the material when compared to metals. An 80% increase in EM absorption (with respect to metal) was observed over a wide frequency range with the novel composite at an overall thickness of only 3 mm. X-ray diffraction (XRD) spectra showed an improvement in the electroactive β-phases in the electrospun PVDF/MWCNTs compared to Plain PVDF. Scanning electron microscopy analysis on various weight percentages of PVDF/MWCNTs revealed the formation of nano fibres with an average diameter of 75–160 nm. In addition, the proposed novel EM wave absorbing composites were of simple configuration and the mechanical properties of the fabricated composites were comparable to that of GFLC. Experimental results indicated that RAS with 0.25 wt % MWCNT/PVDF had 87.5% bandwidth for over 90% absorption from 8.5 to 12 GHz compared to all other configurations. The tailored composite material could be used as excellent radar absorber structures (RAS) and can find tremendous application in the manufacture of stealth aircrafts.

Lean Beef and Beef Fat Interact to Enhance Nonheme Iron Absorption in Rats

Nonheme iron absorption is enhanced when meat replaces non-meat protein sources in a meal. Our objective was to examine the hypothesis that both lean and fat fractions of meat contribute to this enhancement. Weanling rats were assigned, according to a 3 x 3 factorial design, to one of nine nutritionally complete diets formulated to contain various combinations of protein (lean beef, skim milk or egg white) and fat sources (beef fat, milk fat or partially hydrogenated vegetable fat). Diets contained 20% protein and 20% fat. After 4 d of consuming the assigned diets, the rats were deprived of food overnight and offered a meal of their respective diet labeled extrinsically with 59FeCl3. Feeding of the unlabeled diets was continued for 14 d. Iron absorption was estimated from 59Fe retention, monitored by whole-body counting over the 14-d period. Absorption was highest from diets containing beef regardless of the fat source, but the combination of beef and beef fat was highest of all. In the comparison of absorption from the lean beef and other diets, there was significant interaction between lean beef and fat source on iron absorption. These results suggest that the iron absorption-enhancing properties of meat may involve an interaction between the lean and fat fractions of meat.

The effects of Lavandula angustifolia essential oil on analgesic effects and percutaneous absorption of naproxen sodium gel; an in vivo and in vitro study.

The percutaneous bioavailability of naproxen is low and several technologies have been utilized to overcome the problem. Although, some studies have reported the permeation-enhancing properties of natural essential oils, no research has reflected the effectiveness of Lavandula angustifolia essential oil (LAEO) on increasing the percutaneous absorption of naproxen sodium from a topical gel. Therefore, the present study was designed to investigate whether LAEO increased the percutaneous absorption and the analgesic effects of naproxen sodium topical gel. In the present study, naproxen topical gel was formulated using carbopol 940 (a gelling agent) and several vehicles such as PEG 400, ethanol, and water and the properties of gels were measured. Percutaneous absorption-enhancing properties of LAEO were measured too. Based on our data, the essential oil-containing formulation of naproxen represented greater penetration into (222.19 ± 24.87 vs. 107.65 ± 6.38 μg/cm2 ), and also across (22.07 ± 4.42 vs. 13.14 ± 2.87 μg/cm2 ) skin layers compared to the naproxen gel. Additionally, a significant analgesic property was observed in the naproxen topical gel containing 0.5% essential oil during both first and late phases of formalin test, as well as the late phase of tail-flick test. It could be concluded that LAEO significantly enhanced naproxen percutaneous absorption and also its analgesic effects.

Itaconic Acid-based Superabsorbent Polymer Composites Using Cellulose with Enhanced Absorption Properties and Heat Resistance

Itaconic Acid-based Superabsorbent Polymer Composites Using Cellulose with Enhanced Absorption Properties and Heat Resistance

Human Lactobacillus Biosurfactants as Natural Excipients for Nasal Drug Delivery of Hydrocortisone.

The inclusion of a chemical permeation enhancer in a dosage form is considered an effective approach to improve absorption across the nasal mucosa. Herein we evaluated the possibility of exploiting biosurfactants (BS) produced by Lactobacillus gasseri BC9 as innovative natural excipients to improve nasal delivery of hydrocortisone (HC). BC9-BS ability to improve HC solubility and the BS mucoadhesive potential were investigated using the surfactant at a concentration below and above the critical micelle concentration (CMC). In vitro diffusion studies through the biomimetic membrane PermeaPad® and the same synthetic barrier functionalized with a mucin layer were assessed to determine BC9-BS absorption enhancing properties in the absence and presence of the mucus layer. Lastly, the diffusion study was performed across the sheep nasal mucosa using BC9-BS at a concentration below the CMC. Results showed that BC9-BS was able to interact with the main component of the nasal mucosa, and that it allowed for a greater solubilization and also permeation of the drug when it was employed at a low concentration. Overall, it seems that BC9-BS could be a promising alternative to chemical surfactants in the nasal drug delivery field.

TPP-assisted multi-band absorption enhancement in graphene based on Fibonacci quasiperiodic photonic crystal

The multi-channel enhanced absorption properties in graphene monolayer are theoretically studied. It is realized by inserting a graphene monolayer in a dielectric film, which is sandwiched between a metallic film and a Fibonacci quasiperiodic structure. It is shown that three peaks with absorbance above 75% can be achieved, which is attributed to the Tamm plasmon polaritons and multiple photonic stopbands of the Fibonacci dielectric multilayers. Moreover, the distribution of the normalized electric field intensity is simulated to reveal the physical origin of such multichannel absorption effect. The designed graphene absorber possesses ultra-narrow absorption profiles and performs similar to an antenna. Furthermore, the multichannel absorption performances could be flexibly tuned by changing the angle of the incident and the geometric dimensions. Our results may find potential applications in the design of novel photoelectronic devices.

Matrix phase induced boosting photoactive performance of ZnO nanowire turf‐coated Bi2O3 plate composites

AbstractA new nanocomposite consisting of ZnO nanowire turf‐coated Bi2O3 plates was synthesized using a method combining a chemical bath and hydrothermal crystal growth through sputtering ZnO seed layer‐assisted growth. Structural analysis revealed that highly crystalline, high‐density, one‐dimensional (1D) ZnO crystals were uniformly coated on the organized two‐dimensional (2D) Bi2O3 plates with a single β phase or dual α/β polymorphic phases. The Bi2O3–ZnO composites exhibited enhanced absorption properties in the ultraviolet and visible regions compared with pristine Bi2O3 and ZnO. Furthermore, the Bi2O3–ZnO composites exhibited higher photoactive performance than that of the pristine Bi2O3 and ZnO because of the low recombination rate of photoinduced electron−hole pairs caused by the vectorial transfer of electrons and holes between ZnO and Bi2O3 and the substantially increased surface area of the unique composite morphology. The ZnO nanowire turf‐coated Bi2O3 plates with a α/β‐Bi2O3 matrix exhibited photoelectrochemical and photocatalytic properties superior to those of the composite with a single β‐Bi2O3 matrix. The coexistence of α/β homojunction in the Bi2O3 matrix and the abundant heterojunctions between the ZnO nanowires and Bi2O3 plates substantially enhanced photoexcited charge separation efficiency. Growing high‐density 1D ZnO on 2D Bi2O3 via a combination methodology and crystallographic phase control provided a promising material design route for nanocomposite systems with high photoactivity for photoexcited device applications.

Electromagnetic wave attenuation properties of MFe2O4 (M = Mn, Fe, Co, Ni, Cu, Zn) nano-hollow spheres in search of an efficient microwave absorber

In search of light-weight, stable, cost-effective and efficient microwave absorbing material, here, we have investigated electromagnetic wave (EM) attenuation properties of transition metal based MFe2O4 [M = Mn, Fe, Co, Ni, Cu, Zn] nano-hollow spheres in-detail within a widely-used frequency range of 1–20 GHz. The divalent cation, M2+ [M = Mn, Co, Ni, Cu, Zn] substitution in Fe3O4 displays a clear enhancement of EM absorption properties compared to traditional magnetite where MnFe2O4 NHS is found to exhibit an optimal reflection loss (RL) of about − 32.7 dB, total shielding efficiency (SETotal) ~ −42 dB and a high attenuation constant (α) ~ 196 Np/m. Favorable impedance matching, significant dielectric and magnetic loss contribute to the enhancement in absorption properties. Interestingly, with increase in filler concentration (in epoxy resin matrix) from 0 wt% to 50 wt%, MnFe2O4 NHS shows a gradual increase in RL values and an excellent RL of about − 45.6 dB at thickness ~4.2 mm is obtained for 50 wt% composite with a total effective bandwidth (RL < −10 dB i.e. absorption >90%) of ~3.6 GHz. Moreover, analysis of quarter-wavelength model for best matching thickness (tm) displays a good agreement between experimental and simulated tm values. The overall results indicate that ferrites in the form of hollow structures are much more efficient than their bulk counterpart and optimized MnFe2O4 NHS is found to be most suitable for high-frequency applications as an efficient low-cost microwave absorber.

Absorption enhancement of thin layer black phosphorous in the mid-infrared with an all-dielectric metasurface

Infrared (IR) light photodetection based on two dimensional (2D) materials has attracted increasing attention. However, the weak IR absorption in 2D materials due to their inherent atomically thin thickness degrades their performance when used as IR photodetectors. Dielectric metasurfaces have represented fantastic functionalities in realizing high-efficiency wavefront control in the optical and infrared ranges. In this work, we design an all-dielectric phase gradient metasurface in the mid-infrared to improve the limited absorption of black phosphorous (BP). With the elaborately designed metasurface the incident infrared light in the form of plane wave is converted into surface wave, and it is guided to concentrate at the very center of the structure. Enhanced electric field is achieved at the center of the structure. With placement of thin layer BP of 5 µm×5 µm size, the absorption can be enhanced to about 3.77% at 3.6 µm, which is about 20 times larger than that of bare thin layer BP. Different sizes and thickness of the BP are also investigated to demonstrate the effectiveness and flexibility of our design. Owing to the lossless and absorption enhancement properties of our structure, our design may find applications in the upcoming highly efficient 2D photodetectors.

Malposed spoof surface plasmon structure with enhanced microwave absorption and compressive performances realized by carbon-based foams

In this paper, a malposed spoof surface plasmon (SSP) structure filling by carbon-based absorbent polymethacrylimide (PMI) foams is proposed, which realizes the bi-function of broadband electromagnetic (EM) wave absorption and mechanical enhancement properties. The malposed SSP structure is first designed to accomplish high-performance absorption at lower radar frequencies, whose 10-dB level absorptivity is obtained at the range of 4.8–10.2 GHz. After filling carbon-based PMI foams in the interior of hollow SSP structure, the effective absorption bandwidth can be extended largely to 18 GHz. Moreover, the measured results in the mechanical compressive experiment show that the compressive strength σpeak, energy absorption per unit volume Wv and energy absorption per unit mass Wm of the proposed foam-filled SSP structure can reach to 45.4 MPa, 13.57 × 103 KJ/m3 and 38.84 KJ/Kg, respectively, with the density only 0.35 g/cm3, which are more competitive comparing with many metallic sandwich core topologies. It is sure that the broadband microwave absorption performance and enhanced compressive property make our design more multifunctional, and have potential application in the practical stealth designs.

An optimistic approach “from hydrophobic to super hydrophilic nanofibers” for enhanced absorption properties

Water holding capacity becomes essential for hygiene applications including baby diapers. Microfibers of hydrophilic polymers have been useful source for such applications. While, super hydrophilic and stable nanofibers incorporation with functional antibacterial agent are essential to get higher absorption of water along with antimicrobial activity against harmful bacteria. In current work, hydrophobic polymeric nanofibers are transformed to super hydrophilic nanofibers by addition of copper (II) oxide (CuO hereafter) nanoparticles. CuO nanoparticles provided two distinctive properties to existing nanofibers. Firstly, nanofibers surface area was significantly increased, and secondly copper (II) oxide itself is hydrophilic material which imparted hydrophilicity to base polymer. Polyacrylonitrile, crosslinked Polyvinyl Alcohol, and PICT were selected as super hydrophobic polymeric nanofibers. Copper II oxide nanoparticles (same concentration) were added in all polymer solution and electrospun. Surface, morphological, and hydrophilic properties were characterized and it was concluded that copper II oxide is suitable for transforming hydrophobic nanofibers to super hydrophilic nanofibers. Water holding capacity (WHC) was also improved for all prepared nanofiber mats. WHC for PVA/CuO, PAN/CuO, and PICT/CuO were recorded an average of 23 g/g, 21 g/g, and 18 g/g respectively. Combining all useful results from possible characterization of nanofiber mats, it is expected that CuO nanoparticles loaded nanofibers will have potential application as antibacterial, sustainable, and stable replacement of hygiene products.

Double-layer absorbers based on hierarchical MXene composites for microwave absorption through optimal combination

Abstract