Ca Films Research Articles

Microstructural and Mechanical Properties of Calcium-Treated Cactus Pear Mucilage (Opuntia spp.), Pectin and Alginate Single-Biopolymer Films.

Pectin and alginate satisfy multiple functional requirements in the food industry, especially relating to natural packaging formulation. The continuous need for economic and environmental benefits has promoted sourcing and investigating alternative biomaterials, such as cactus pear mucilage from the cladodes of Opuntia spp., as natural packaging alternatives. The structural and mechanical properties of mucilage, pectin and alginate films developed at a 5% (w/w) concentration were modified by treating the films with calcium (Ca) in the calcium chloride (CaCl2) form. Scanning electron microscopy (SEM) showed the 5% (w/w) 'Algerian' and 'Morado' films to display considerable microstructure variation compared to the 5% (w/w) pectin and alginate films, with calcium treatment of the films influencing homogeneity and film orientation. Treating the alginate films with a 10% (w/w) stock CaCl2 solution significantly increased (p < 0.05) the alginate films' tensile strength (TS) and puncture force (PF) values. Consequently, the alginate films reported significantly higher (p < 0.05) film strength (TS and PF) than the pectin + Ca and mucilage + Ca films. The mucilage film's elasticity was negatively influenced by CaCl2, while the pectin and alginate films' elasticity was positively influenced by calcium treatment. These results suggest that the overall decreased calcium sensitivity and poor mechanical strength displayed by 'the Algerian' and 'Morado' films would not make them viable replacements for the commercial pectin and alginate films unless alternative applications were found.

Effect of propionyl group on birefringence and wavelength dispersion of propionylated cellulose acetate optical compensation films

Propionylated cellulose acetate (PCA) with different propionyl substitution degrees (DSPr) was synthesized, and the corresponding optical films were prepared by solution casting. The birefringence and its wavelength dispersion of PCA films stretched at 10 °C above and below the glass transition temperature (Tg) with different draw ratios (DR) were studied. The introduction of propionyl group at different substitution sites present different contribution to birefringence and its wavelength dispersion. The propionyl group at C-2 and C-3 sites have a larger positive orientation birefringence with stronger normal wavelength dispersion, while that at the C-6 site shows a smaller negative orientation birefringence with weaker normal wavelength dispersion compared with the acetyl group. Compared with CA film, the introduction of the propionyl group weakens the orientation birefringence of PCA film. With the increase of DSPr from 0.023 to 0.303, the occurrence of propionyl substitution only at the C-6 site turns to C-2, C-3 and C-6 sites and the wavelength dispersion of in-plane birefringence (Δnin) decreases. When DSPr is further increased to 0.537, the Δnin and out-of-plane birefringence (Δnth) of PCA films at different DR show a very weak wavelength dispersion with the relative horizontal curves. Current results indicate that when the substitution degree of the propionyl group and acetyl group is suitable, the wavelength dispersion of PCA film can be eliminated.

Self-powered ultraviolet photodetectors based on CuInO2: Ca/GaN epitaxial heterojunction

In this paper, calcium-doped p-type CuInO2 (CuInO2:Ca) epitaxial films with c axis preferred orientation were grown on n-type GaN (001) substrates by the pulsed laser deposition (PLD) technology, and CuInO2/GaN p-n heterojunction photodetectors were fabricated based on the prepared CuInO2 films. The lattice structure, surface morphology, energy band structure, composition, and electrical properties of the grown CuInO2:Ca films were characterized. Compared with the undoped and Ca-doped (1 at.%) films, the photoresponsivity (R), detectability (D*) and rise (τr)/decay (τd) time of the detector based on the CuInO2:Ca (2 at.%)) film with the best crystal quality are 1.13 mA/W, 9.9 × 1010 Jones, and 0.14/0.1 s, under the irradiation of 365 nm (21.5 mW/cm2) UV light with 0 V bias, respectively, and can achieve a maximum R-value of 1.6 mA/W under the lowest light intensity (2.4 mW/cm2). The results indicate that the self-powered UV photodetectors based on CuInO2/GaN p-n heterojunctions have potential applications in the field of optoelectronic devices.

The effect of interdiffusion during formation of epitaxial Ca intercalated layered silicene film on its thermoelectric power factor

Deformation of silicene buckled structure attracts great interest for the possibility of ultrahigh thermoelectric power factor. Therefore, the control method of silicene buckled structure is needed. Here, we developed the method to control composition ratio in epitaxial Ca intercalated layered silicene (CaSi2) film formed by solid phase epitaxy through an atomic interdiffusion between Ca films and Si substrate because of the possible existence of the relation between silicene buckled structure in CaSi2 film and the composition ratio. The interdiffusion is controlled by introducing hydrogen-terminated layer as an interface layer between Ca and Si substrate, resulting in the control of the composition ratio in CaSi2 film. Moreover, we find that the CaSi2 films with different composition ratio exhibit different thermoelectric power factors. This study reveals that introducing the interface layer for interdiffusion control is an effective way to control the composition ratio and to form metastable high-buckled silicene with high power factor.

Catalysis of MnO2-cellulose acetate composite films in DBD plasma system and sulfamethoxazole degradation by the synergistic effect

Herein, dielectric barrier discharge (DBD) plasma and MnO2-cellulose acetate (MnO2/CA) composite films was coupled together to degrade sulfamethoxazole (SMX) in water. The MnO2/CA composite films were firstly prepared successfully though heating blending method in this study and then characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Raman spectra, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TG). Catalytic effect of the MnO2/CA films was investigated by comparing the removal percentages, the kinetic constants, the energy utilization efficiencies (G50) as well as the COD and TOC removal during the SMX degradation in the DBD plasma system with or without the MnO2/CA films addition under different reaction conditions. The optimal catalytic performance was obtained by adding the 3% MnO2/CA films into the DBD plasma system and the alkaline solution condition was favorable for the SMX degradation. After four times using, the MnO2/CA composite films still maintained the catalytic activity. Catalytic mechanism of the MnO2/CA films was speculated by analyzing the changes of solution pH and conductivity during the reaction, concentrations of the formed O3 and H2O2 in water and the generated active species (1O2 and ·OH) in both the DBD plasma system and the DBD-MnO2/CA films system. The quenching test was also carried out to figure out the important effect of the ·O2−, 1O2 and ·OH for the SMX degradation in the synergistic system. Finally, LC-MS was used to analyze the main intermediates generated during the SMX degradation and the possible degradation pathways were accordingly speculated. The research could provide a new direction for the development and application of the DBD plasma technology as well we the composite films catalyst.

Sustainable chitosan films containing a betaine-based deep eutectic solvent and lignin: Physicochemical, antioxidant, and antimicrobial properties

Biodegradable chitosan films are highly desirable for use as food packaging, but the poor mechanical properties, water sensitivity, and functional limitations of these films must be addressed. In this study, a new chitosan film was prepared from chitosan–citric acid/chitosan–adipic acid (CA) and chitosan–malic acid/chitosan–adipic acid (MA) solutions and plasticized by the incorporation of a natural betaine-based deep eutectic solvent (DES; 0–30 wt%) and lignin (1 wt%). The resultant films were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy, and X-ray diffractometry to evaluate the changes in the structural, physical, antioxidant, and antimicrobial properties. Analysis revealed that the films contain numerous particles in cross-section and have rough surfaces. Furthermore, the addition of 30 wt% DES with lignin resulted in a significant increase in the elasticity, water contact angle, and radical scavenging rate. Moreover, the presence of lignin in the films reduced the water vapor permeability because of its hydrophobicity. Additionally, the CA film containing lignin displayed good antibacterial activity against Staphylococcus aureus and Escherichia coli. Overall, the CA-based composite films demonstrated excellent potential for use as bioactive food packaging application.

Reducing cherry rain-cracking: Development and characterization of cold-water fish gelatin films reinforced by dual rod-spherical nanoscale structures formed under magnetic fields

In order to solve the problem of cherry rain-cracking, cold-water fish gelatin (CFG)-based edible films (CFG, CFG-CNC [cellulose nanocrystals], CFG-CA [chitosan hydrochloride-sodium alginate nanoparticles], CFG–CNC–CA, and their magnetic field [MF] films) were prepared with reinforcement by rod-spherical dual-nanoscale structures. Here, the spherical nanoparticles CA were formed based on static electricity interaction between chitosan hydrochloride and sodium alginate according to pre-gel method, whereas the rods consisted of CNC extracted from sugarcane bagasse. Studies were conducted in laboratory to determine the coating-ductility, hydrophobic, water-vapor barrier, mechanical, and retention properties, and in the field to determine cracking index (CI) and cracking ratio (CR). MF treatment was found to induce the rod-spherical dual-nanoparticles to arrange into C–O–C linkages. Compared to the other films, the CFG–CNC–CA (MF) film showed superior coating-ductility properties (surface tension: 61.8 mN m−1), hydrophobicity (water contact angle: 111.6°), and water-vapor barrier (water-vapor permeability: 7.43 × 10−10 gm−1Pa−1s−1), as well as superior mechanical (Young's modulus: 351 MPa; tensile strength: 30.1 MPa) and retention properties on cherry (water solubility: 38.4%; swelling degree: 876%). Compared with the experimental control, the total CI of cherries treated with CFG–CNC–CA (MF) was reduced from 43.3% to 11.8%, and the total CR was reduced from 34.8% to 11.1%, type Ⅰ’ cracking in particular experienced a greater reduction (from 26.7% to 9.16%) than did type Ⅱ’ (13.7%–4.96%) or Ⅲ’ (8.90%–3.48%). Thus, this study successfully provided a reference for edible CFG–CNC–CA (MF) coatings that prevent and control cherry rain-cracking disasters worldwide in a timely, safe, and efficient manner.

Degradation of Cellulose Acetate in Simulated Aqueous Environments: One‐Year Study

AbstractCellulose acetate (CA) is subjected to different aqueous environments (e.g., lake water, seawater, artificial seawater) under controlled laboratory conditions to investigate the degradation potential in natural water systems. The main changes in the CA films are detected during the first months of the 12‐month study. Approximately 5% and 10% weight losses are observed during the first month of aging at RT and at 60 °C, respectively. The temperature effect is rather negligible and the weight loss also does not significantly increase on prolonged aging. A quantitative high‐performance liquid chromatography analysis shows that this weight loss is mainly caused by deacetylation and depending on the aging conditions, 10–30% of the acetate groups are lost during the first 1–3 months of aging. Fourier transform infrared and nuclear magnetic resonance analyses further support this. It is well established that a high degree of substitution (DS) is the bottleneck for biodegradation of CA and a significantly higher biodegradation rate has been demonstrated for CA materials with degree of substitution, DS&lt;2, compared to those with DS&gt;2. The degree of deacetylation observed here is enough to decrease the DS to below 2, which can therefore have a significant effect on the subsequent biodegradation.

ZnO:Ca MSM ultraviolet photodetectors

Photoresponse of calcium doped zinc oxide (ZnO:Ca) metal-semiconductor-metal (MSM) UV detectors are reported. Photosensitive ZnO:Ca films exhibit high transparency in the visible region, show polycrystalline, hexagonal wurtzite structure, having c-axis preferred growth. Noticed redshift of 60 meV in the optical band gap for ZnO:Ca (3 wt%) thin film is attributed to increased crystallite size. Improved n-type conductivity in ZnO with Ca doping is due to increased carrier concentration, MSM photodetector fabricated with, 3 wt% Ca doped ZnO exhibit higher responsivity of 3.05A/W at 365 nm UV illumination. Transient response measurements show reasonably fast switching with a rise and fall time of 15s and 26s respectively. The obtained results suggest, ZnO:Ca can be used as active material in the fabrication of UV photodetectors.

Effect of endogenous chloride ion content and mineral admixtures on the passivation behavior of reinforcement embedded in sea-sand ultra-high performance concrete matrix

Ultra-high performance concrete (UHPC) is typically defined as an advanced cementitious material which exhibits excellent mechanical property and superior durability. The development of UHPC made with sea-sand addresses the challenges associated with the shortage of river sand in producing concrete for a marine construction. In this study, UHPC matrix was prepared by using simulated sea sand with different levels of chloride and mineral admixtures included fly ash and slag. The passivation behavior of steel bars embedded in sea-sand UHPC specimens were investigated by electrochemical workstation. In addition, the microstructure of sea-sand UHPC matrix was characterized by rapid chloride test, alkalinity test and SEM-EDS. The experimental results showed that in the early age, the alkalinity of sea-sand UHPC matrix increases with the increment of endogenous chloride ion, and the introduction of fly ash in the matrix has higher alkalinity than slag. The corrosion current density icorr of steel bar in sea-sand UHPC gradually decreases with the age, and essentially being lower than 0.1 µA/cm2. Due to the pozzolanic effect, the utilization of fly ash and slag prolongs the stabilization age of icorr evolution. The reinforcement embedded is able to be in the stable passive state regardless of the endogenous chloride ion content. The incorporation of fly ash and slag has little effect on the densification of passivation film. Compared to the endogenous chloride ion level, the alkalinity of matrix has a more significant effect on the growth of the charge transfer resistance of steel bars in sea-sand UHPC, which is associated with the denser passive film and built-up of Ca(OH)2 layer near the steel bars.

Giant Enhancement of Seebeck Coefficient by Deformation of Silicene Buckled Structure in Calcium‐Intercalated Layered Silicene Film (Adv. Mater. Interfaces 1/2022)

Ca-Intercalated Layered Silicene (CaSi2) with Deformed Buckled Structure In article number 2101752, Tsukasa Terada, Yoshiaki Nakamura, and co-workers reveal that in epitaxial film of Ca intercalated layered silicene, CaSi2 on Si substrate, the silicene buckled structure is deformed through the control of the Ca/Si ratio. This deformation causes giant enhancement of Seebeck coefficient due to band structure change, leading to high thermoelectric power factor.

Protective Langmuir–Blodgett coatings based on long-chain fatty acids

The morphology and tribotechnical properties of Langmuir–Blodgett (LB) monolayers and multilayers of some fatty acids, such as nervonic (NA), cerotic (CA) and montanic acids (OCA), was investigated. It was established that the wear resistance of silicon surface coated by LB monolayer of OCA is greater by 11 and 1.3 times in comparison with the LB monomolecular films of NA and CA, respectively. The multilayer of OCA, formed by 140 layers, increases the stability of steel surface by 35 times.

Safe preparation of CuN3 for improved ignition performance of Ni-Cr bridge wire electric initiating explosive devices

The electric initiating explosive devices (EIEDs) are playing an increasingly important role in both military and civilian applications. With respect to good electrical conductivity and flexural strength, carbon paper can be endowed with primary explosive so that it serves as an independent module just like an ignition component in the EIEDs to satisfy the modular integration of EIEDs. But a traditional primary explosive cannot meet the need of sustainably developed devices. New energetic films need to be designed for EIEDs. The heat release and activation energy of the CA-CP film are 1402 J·g−1 and 104 kJ·mol−1, respectively. The electrostatic sensitivity of the CA film, whose E50 reaches up to 4.81 mJ, has been well improved due to its interweaved fibers. Moreover, the cuprous azide film could be successfully ignited under water after a hydrophobicity treatment. Herein, the CA-loaded carbon paper has been successfully integrated with the Ni-Cr bridge EIEDs for a greatly improved ignition performance, which will subsequently lead to a vast enhancement in the ability of EIEDs to ignite the secondary explosives or devices.

Observable removal of pharmaceutical residues by highly porous photoactive cellulose acetate@MIL-MOF film

Pharmaceutical products are used tremendously worldwide and subsequently released into wastewater even at very low concentration caused serious environmental problem due to their high activity. Therefore, the present work focuses on remarkable removal of paracetamol as one from the most used pharmaceutical intermediates, by using porous film based on cellulose acetate@metal organic framework (CA@Ti-MIL-NH2). The film was designed to achieve extreme removal of paracetamol by action of both of adsorption and degradation. Metal organic frame work was directly synthesized and inserted within the pre-prepared porous CA film to obtain porous CA@Ti-MIL-NH2 film. The synthesized films were applied in adsorption and photo-degradation of paracetamol separately and together. Due to the photocatalytic activity of Ti-MIL-NH2, the photo-degradation of paracetamol in visible-light was much effective and considerably high degradation of paracetamol was observed (k1 = 760.0 m−1) comparing to the adsorption (k1 = 160.0 m−1). The overall removal of paracetamol was significantly enlarged from 82.7 mg/g for CA film to 519.1 mg/g for porous CA@Ti-MIL-NH2 film. The used film exhibited quite good reusability and the removal of paracetamol was lowered from 96% to 85% after 5 regeneration cycles. Results of total organic carbon confirmed that paracetamol was fully degraded to CO2 and water.

Tuning of the Optoelectronic Properties for Transparent Oxide Semiconductor ASnO3 by Modulating the Size of A-Ions

Recently, La-doped ASnO3 (A = Ba, Sr, and Ca) films have attracted increasing attention as an active channel of deep-ultraviolet transparent thin-film transistors, owing to their wide band gap and ...

Fabrication of cellulose acetate‐based radiation grafted anion exchange membranes for fuel cell application

AbstractNovel cellulose acetate‐based anion exchange membranes (CA‐AEM) are successfully synthesized via gamma radiation grafting as a possible renewable alternative to commercial AEMs. Using CA film precursors with degree of acetylation of 2.5, the synthesized AEM shows a high ion exchange capacity of 2.15 mmol g−1 obtained at high degree of grafting of 45%. It was determined using thermogravimetric analysis that the radiation‐grafted CA‐AEM has stable amine functional groups under oxygen environment within the normal operating temperature range of alkaline fuel cells. The CA‐AEM also exhibits appreciable performance over a range of temperatures, with a highest ionic conductivity of up to 0.163 S cm−1 depending on the synthesis parameters. Results revealed that membranes prepared using gamma radiation dose of 31 kGy and above are susceptible to mechanical and dimensional instability due to increased water uptake and degree of swelling. Further study should consider the balance between grafting parameters and the desired hydrophysical properties.

Preparation and performance analysis of novel liquid crystal alignment films based on macromolecular photosensitiser and photosensitive polyimide

ABSTRACT A photosensitive polyimide (BF-CA) and a macromolecular photosensitiser (BB-CA) are successfully synthesised. The BF&BB-CA blend films based on BF-CA and BB-CA can induce uniform alignment of liquid crystal (LC) after the non-polarised ultraviolet light (NPUVL) exposure for 15 min. After exposure for the same time, LC alignment ability of the BF&BB-CA blend films is higher than that of BF-CA films and BB-CA films. The alignment performance of LC and pretilt angles induced by the BF&BB-CA films after treatment at 120°C for 4 h are nearly unchanged, indicating that the prepared films have excellent thermal stability. Furthermore, the pretilt angle of the LC cells is 0.5°, which can be used in In-Plane Switching mode LCD.

Experimental and theoretical studies of cinnamyl alcohol as a novel corrosion inhibitor for copper foils in rolling oil

AbstractCinnamyl alcohol (CA) was added to the rolling oil of copper foils as a novel corrosion inhibitor, and its anticorrosion performance and mechanism were studied using potentiodynamic polarization and electrochemical impedance spectroscopy. Microstructure and chemical composition of the copper electrode surface were analyzed by scanning electron microscopy, energy‐dispersive spectroscopy, and X‐ray photoelectron spectroscopy. The results showed that CA acted as a mixed‐type inhibitor, and the maximum inhibition efficiency of 87.7% was achieved at 2.4 mM. Moreover, a protective film was formed on the copper surface, which attributed to the C–OH groups in the CA molecule. The absorption of CA on the copper surface was physisorption, which conformed to Langmuir adsorption isotherm, with a standard adsorption free energy of −11.38 kJ/mol. In the presence of CA, some flaky corrosion products changed into granular corrosion products. The synergistic effect of the granular corrosion products (copper chloride hydroxide) and the CA film further decreased the corrosion rate.

Enhanced photovoltaic effect in Ca and Mn co-doped BiFeO3 epitaxial thin films

In this work, we proposed modification of BiFeO3 (BFO) by Mn and Ca co-doping, and realized the epitaxial growth of Bi0.98Ca0.02Fe0.95Mn0.05O3 (BCFMO) thin films on (100)-oriented SrTiO3 (STO) substrates with a SrRuO3 (SRO) buffer layer via pulsed laser deposition (PLD). A decreased bandgap (Eg = 2.41 eV) and enhanced remanent polarization (Pr = 92.5 μC/cm2) were simultaneously achieved in the BCFMO thin film. A tunable photovoltaic (PV) effect by changing the direction of the poling electric field was observed in the BCFMO-based device. We investigated the PV mechanism for the device by analyzing its band structure and attribute it to the coupling effects of the ferroelectric depolarization field and the interface Schottky barriers. The BCFMO-based device under favorable upward poling shows the best PV performance with an open-circuit voltage (Voc) of −0.29 V and short-circuit current density (Jsc) of 0.26 mA/cm2, which are much higher than those for the BFO-based device (Voc = -0.11 V, Jsc = 0.08 mA/cm2), resulting from the narrower bandgap and larger Pr in the BCFMO film. The approach of simultaneously introducing Ca and Mn into the BFO, enabling both a higher polarization and narrower bandgap, opens a new way for improving the performance of BFO-based PV devices.

Employable metal (Ag & Pd)@MIL-125-NH2@cellulose acetate film for visible-light driven photocatalysis for reduction of nitro-aromatics

The effective and reusable photocatalyst film based on metal @metal organic framework@cellulose acetate [metal (Ag & Pd)@MIL-125-NH2@CA] was systematically studied. Nano-silver was grown over the crystalline disc of MIL-125-NH2 within CA film, while, self-assembly of crystalline trees like the structure of Pd)@MIL-125-NH2 was observed inside CA matrix. The calculated band gap was diminished from 2.53 eV to 2.38–1.99 eV after doping of metal (Ag & Pd) within MIL-125-NH2@CA film. Compared to MIL-125-NH2@CA; metal (Ag & Pd)@MIL-125-NH2@CA film showed a considerably higher photocatalytic reduction of nitro-aromatics in visible light. After 60 min, 80.6–93.5 % of 2-nitrophenol was photoreduced when metal (Ag & Pd)@MIL-125-NH2@CA film was used. After 5 recycles, the photoreduction percentage of 2-nitrophenol was lowered to 54.4–62.0. The produced metal@MIL-125-NH2@CA films showed an effective photocatalytic reduction of nitro-aromatics in the visible light, reflecting their promising performance in preparation of intermediates useful in many industrial products.