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The aim of this study was to prepare a novel pH-sensitive smart film based on the addition of purple garlic peel extract (PGE) and TiO2 nanoparticles in a sodium alginate (SA)/polyvinyl alcohol (PVA) matrix to monitor the freshness of beef. FT-IR spectroscopy revealed the formation of stronger interaction forces between PVA/SA, PGE, and TiO2 nanoparticles, which showed good compatibility. In addition, the addition of PGE improved the tensile strength and elongation at break of the composite film, especially in different pH environments, and the color response was obvious. The addition of 1% TiO2 nanoparticles significantly improved the mechanical properties of the film, as well as the light barrier properties of the film. PGE could effectively be uniformly dispersed into the composite film, but it also had a certain slow-release effect on the release of PGE. PGE had high sensitivity under different pH conditions with rich color changes, and the color showed a clear color change from red to yellow-green when the pH increased from 1 to 14. The same change was observed when it was added to the film. In particular, by applying this film to the process of beef preservation, we judged the freshness of beef by monitoring the changes in the TVB-N value and pH value during the storage process of beef and found that the film showed obvious color changes during the storage process of beef, from blue (indicating freshness) to red (indicating non-freshness), and finally to yellow-green (indicating deterioration), which indicated that the color change of the film and the freshness of the beef maintained a highly consistent. [ABSTRACT FROM AUTHOR]

The aim of research was to fabricate a novel indicator by using κ-carrageenan and quince seed mucilage (QSM) hydrogels and red cabbage anthocyanin. The porosity of the hydrogel was controlled using different ratios of κ-carrageenan(C):QSM(Q) (C90:Q10, C70:Q30, and C50:Q50). The hardness of hydrogels decreased from 28.6 ± 0.3 N for C90Q10 to 11.0 ± 1.0 N for C50Q50 sample. However, according to field emission scanning electron microscopy (FE-SEM) analysis, the C50R50 sample had the best morphology with smooth surface and uniform interconnected porous network. Hydrogen bonding interactions among anthocyanins, QSM, and κ-carrageenan were confirmed by Fourier transforms infrared (FT-IR) spectroscopy. The indicator showed a color variation from red to yellow over the pH range of 2–12. Also, the indicator exhibited high sensitivity to ammonia vapors (S RGB = 115%) and good color stability. The C50QRA indicator was used for monitoring rainbow trout fillet spoilage and revealed a visually-detectable color change from red to green upon detecting total volatile basic nitrogen (TVB-N) content produced throughout storage at 4 °C. Generally, the halochromic hydrogel developed in this research can be suggested as a more sensitive and accurate freshness indicator than conventional indicator solid supports. • Novel Ҡ-carrageenan/quince seed mucilage/RCA based hydrogel was prepared. • Quince seed mucilage improved the thermal/morphological properties of hydrogels. • Distinct color variation of intelligent hydrogel over the pH range was observed. • Hydrogel-based indicators had high sensitivity to ammonia and color stability. • Smart hydrogel had excellent accuracy in monitoring the freshness of fish fillets. [ABSTRACT FROM AUTHOR]

In this study, a simple pH-colorimetric film was developed to detect the spoilage of pasteurized milk. The biosensor was fabricated by incorporating the pH-sensitive anthocyanins (AC) extracted from blue pea (Clitoria ternatea L.) flower into a starch-based edible film. The color responses of both AC aqueous extracts and edible films incorporated with different AC concentrations towards different pH buffers (pH 2–11) were measured using Ultraviolet–visible (UV–Vis) spectrophotometer and colorimeter, respectively. Based on the results, there were significant differences (p < 0.05) for both total color changes (∆E) and L*a*b color system of the pH-sensitive edible film in different pH buffers. It indicated that the AC incorporated edible films were able to exhibit color changes over a wide range of pH. The potential application of the pH-sensitive film in spoilage detection was then carried out. Color changes of the film in commercial pasteurized milk were measured at predetermined intervals (24, 48, and 72 h) under storage conditions of 25 °C. Meanwhile, milk samples were collected for the microbiological test [total plate count (TPC)]. Results showed that the pH-sensitive films were able to detect pH changes of pasteurized milk which was associated with milk spoilage with visually observable color changes from deep blue to a light blue and showed a significant ∆E (p < 0.05) of 19.95 ± 0.009. The ∆E of the films in spoilage detection has a significant correlation with the pH changes of milk (R = − 0.9932) and TPC with a desirable coefficient (R = 0.9918). Therefore, the pH-sensitive edible film can provide a highly sensitive and non-destructive way of monitoring the food quality or spoilage without creating safety issues in the food industry. [ABSTRACT FROM AUTHOR]

In this study, a multi-functional cotton fiber was prepared and investigated for the visual detection and enhanced adsorption of cadmium (Cd) ions in aqueous solutions. SI-ATRP technology was used to graft poly (glycidyl methacrylate) (PGMA) and poly (3-sulfopropyl methacrylate potassium salt) (PSMP) successively on the surface of the cotton fiber. Then, diethylenetriamine (DETA) and 5,10,15,20-tetrakis(1-methy-4-pyridinio)porphyrin tetra(p-toluenesulfonate) (TMPyP) were immobilized onto the PGMA and PSMP polymer brush, respectively, to form the Cotton-PGMA(DETA)-PSMP(TMPyP) (abbreviated as C-PD-PT) material. C-PD-PT showed enhanced Cd ion adsorption with the maximum adsorption capacity of 1.6215 mmol/g derived from the Langmuir model fitting. In addition, The C-PD-PT material exhibited simple visual detection of Cd ions with a remarkable color change from brownish to green. A linear relationship between the light absorbance of C-PD-PT-Cd (C-PD-PT adsorbed with Cd ions) and the initial concentrations of Cd ions was established, which would be used for the fast determination of Cd ion concentrations in aqueous solutions. [ABSTRACT FROM AUTHOR]

In this study, a porphyrin functionalized cotton fiber was prepared and investigated for the visual detection and efficient adsorption of cadmium (Cd 2+ ) ions in aqueous solutions. The pristine cotton fiber was first grafted with poly (3-sulfopropyl methacrylate potassium salt) (PSMP) via the surface-initiated atom transfer radical polymerization (SI-ATRP), and subsequently immobilized with 5,10,15,20-tetrakis(1-methy-4-pyridinio)porphyrin tetra(p-toluenesulfonate) (TMPyP), to form the CPT (Cotton-PSMP-TMPyP) material. The CPT was characterized by SEM, FTIR, XPS and elemental analysis, and examined for the detection and adsorption of cadmium ions. The influencing factors such as pH and the initial cadmium ion concentrations on the adsorption performances were investigated. Results showed that the cadmium ion adsorption isotherm was best fitted with the Langmuir isotherm model, with the derived maximum adsorption capacity of 0.8638 mmol/g. The thermodynamic study showed the endothermic nature of the adsorption process. In addition, the adsorption kinetics was fast with over 90% of the total cadmium ions adsorbed within 2 min. Furthermore, the distinctive color response of the CPT to the cadmium ions in aqueous solutions was clearly displayed. A linear relationship between the light absorbance of CPT-Cd (CPT adsorbed with cadmium ions) and the initial concentrations of cadmium ions was successfully established, which could be used for the fast determination of the cadmium ion concentrations in aqueous solutions. [ABSTRACT FROM AUTHOR]

Visual indicator bi-layer films were manufactured incorporating κ-carrageenan, butterfly pea flower anthocyanin, varying Nano‑titanium dioxide (TiO 2) content and agar for Penaeus chinensis (Chinese white shrimp) freshness detection. The κ-carrageenan-anthocyanin (CA) layer served as indicator, while the TiO 2 -agar (TA) layer functioned as the protective layer to improve the photostability of film. The bi-layer structure was characterized by scanning electron microscopy (SEM). The TA2-CA film had the best tensile strength with a value of 17.8 MPa and the lowest water vapor permeability (WVP) value of bi-layer films was 2.98 × 10−7 g.m−1.h−1.pa−1. The bi-layer film protected anthocyanin against exudation when immersed in aqueous solution of varying pH. The TiO 2 particles filled the pores of the protective layer, increasing the opacity from 1.61 up to 4.49 significantly improving the photostability with a consequent slight color change under illumination of UV/visible light. Under UV irradiation, the TA2-CA film had no significant color change with a ΔE value of 4.23. Finally, the TA2-CA films showed an obvious color change from blue to yellow green in the early stages of Penaeus chinensis putrefaction (≤48 h) then the color change and Penaeus chinensis freshness were well correlated (R 2 = 0.8739). [Display omitted] • Visual indicator bi-layer film was manufactured with indicator and protective layer. • The TA protective layer effectively increased the photo-stability of the films. • The TA-CA bi-layer films present obvious color changes to ammonia and pH. • The TA2-CA films were potential in monitoring Penaeus chinensis freshness. [ABSTRACT FROM AUTHOR]

A pH-sensitive intelligent film was prepared using gelatin as base substrate and purple cabbage anthocyanins (PCA) as indicator with the aid of ultrasound. Fourier transforms infrared and X-ray diffraction analysis showed that 600 W ultrasound brought changes to characteristic bands of gelatin and PCA, and flattened diffraction peak around 2θ = 20°. Film prepared with 600 W ultrasound exhibited high tensile strength and elongation at break and showed high transition temperature and surface hydrophobicity by differential scanning calorimetry and contact angle analysis. The incorporation of <0.35 % PCA had no effect on mechanical properties of films, but it improved the antioxidative activity. Films with 0.14 %, 0.21 % and 0.28 % PCA suggested pronounced color difference at pH 5–8, in accordance with the sharp ΔE difference. Films with 0.28 % PCA was applied for monitoring chilled-stored fish quality. It showed visible color change from pink to atrovirens during storage. The difference of ΔE at various days was ≥5 and ΔE highly correlated with total volatile basic nitrogen. Therefore, gelatin along with PCA under appropriate ultrasound treatment could prepare intelligent film to preserve and monitor the quality of chilled-stored fish. [Display omitted] • Color of PCA responded to the changes of pH distinctively. • Ultrasound 600 W improved film structure and mechanical properties. • Incorporating <0.35 % PCA would not affect film mechanical properties. • Films with 0.28 % PCA monitored fish quality well with visible color change. [ABSTRACT FROM AUTHOR]

ABSTRACT Makrofol BL 2-4 is an extrusion film based on Makrolon polycarbonate. It is different from Makrofol DE as it comprises excellent die-cutting performance combined with high light transmission and moderate light scattering properties. It is a polymeric solid-state nuclear track detector, which has many applications in various radiation detection fields. Samples from Makrofol BL sheets were irradiated using different electron beam doses ranging from 20 to 300 kGy. It is worth mentioning that this report is almost the first one dealing with this topic of material changes using Makrofol BL 2-4. The resultant effect of electron beam irradiation on the properties of Makrofol has been investigated using X-ray diffraction, intrinsic viscosity, Fourier transform infrared spectroscopy, thermogravimetric analysis, refractive index, and color difference studies. The results indicate that the electron beam irradiation in the dose range 50-200 kGy led to the dominance of cross-linking, enhancing the properties of Makrofol. [ABSTRACT FROM AUTHOR]

Makrofol BL 2–4 is an extrusion film based on Makrolon polycarbonate. It comprises excellent die-cutting performance combined with high light transmission and moderate light scattering properties. It is a class of polymeric solid state nuclear track detectors which has many applications in various radiation detection fields. In the present work, Makrofol samples were irradiated using different gamma doses ranging from 10 to 350 kGy. The structural modifications in the gamma-irradiated Makrofol samples have been studied as a function of dose using different characterization techniques such as X-ray diffraction, intrinsic viscosity, Fourier transform infrared spectroscopy, thermogravimetric analysis, refractive index and color difference studies. The gamma irradiation in the dose range 20–200 kGy led to a more compact structure of Makrofol polymer, which resulted in an improvement in its thermal stability with an enhancement in its structural and optical properties. [ABSTRACT FROM PUBLISHER]

A series of field trials were used to assess the practicality of using sticky traps to monitor populations of green spruce aphid, Elatobium abietinum (Walker), in plantations of Sitka spruce. The highest numbers of alate E. abietinum were caught on sticky traps placed in the upper third of the live canopy at 9-17 m above the ground, whereas low numbers of aphids were caught just below the live canopy or at 2 m above the ground. Trials in 2005 with sticky traps of different colors showed that significantly more alate E. abietinum were caught on yellow, red, and green sticky traps than on white, blue, and black traps. A repeat trial in 2007 resulted in significantly more alate aphids being caught on red sticky traps than on traps of any other color except for green. Attraction to red is unusual among aphids, as aphids are thought not to possess a red-sensitive photoreceptor. The attraction of E. abietinum to red-colored sticky traps suggests that conifer-feeding aphids might have a fundamentally different color response compared with aphids that live on cereals, grasses, or herbaceous plants. Alternatively, the attraction to red might be a physiological artifact related to the presence of red-screening pigments in the aphid's compound eye. [ABSTRACT FROM AUTHOR]

Samples from Cellulose triacetate (CTA) sheets were irradiated with electron beam in the dose range 10–200 kGy. Non-isothermal studies were carried out using thermogravimetric analysis (TGA) to obtain the activation energy of thermal decomposition for CTA polymer. The CTA samples decompose in one main break down stage. The results indicate that the irradiation by electron beam in the dose range 80–200 kGy increases the thermal stability of the polymer samples. Also, the variation of melting temperatures with the electron dose has been determined using differential thermal analysis (DTA). The CTA polymer is characterized by the appearance of one endothermic peak due to melting. It is found that the irradiation in the dose range 10–80 kGy causes defects generation that splits the crystals depressing the melting temperature, while at higher doses (80–200 kGy), the thickness of crystalline structure (lamellae) is increased, thus the melting temperature increases. In addition, the transmission of these samples in the wavelength range 200–2500 nm, as well as any color changes, were studied. The color intensity Δ E* was greatly increased on increasing the electron beam dose, and accompanied by a significant increase in the blue color component. [ABSTRACT FROM AUTHOR]

Abstract: Cellulose triacetate (CTA) is a polymer which is widely used in a variety of applications in the field of radiation dosimetry. In the present work, CTA samples were irradiated by electron beam in the dose range 10–200kGy. The modifications in the electron irradiated CTA samples as a function of dose have been studied through different characterization techniques such as thermogravimetric analysis, differential thermal analysis and color-difference studies. The electron irradiation in the dose range 80–200kGy led to a more compact structure of CTA polymer, which resulted in an improvement in its thermal stability with an increase in activation energy of thermal decomposition. Also, the variation of melting temperatures with the electron dose has been determined using differential thermal analysis (DTA). The CTA polymer is characterized by the appearance of one endothermic peak due to melting. The results showed that the irradiation in the dose range 10–80kGy causes defects generation that splits the crystals depressing the melting temperature, while at higher doses (80–200kGy), the thickness of crystalline structures (lamellae) is increased, thus the melting temperature increased. In addition, the transmission of these samples in the wavelength range 200–2500nm, as well as any color changes, was studied. The color intensity ΔE * was greatly increased with increasing the electron beam dose, and accompanied with a significant increase in the blue color component. [Copyright &y& Elsevier]

Abstract: Makrofol-De Polycarbonate is a class of polymeric solid state nuclear track detector which has many applications in various radiation detection fields. In the present work, Makrofol samples were irradiated using different fluences of 1MeV protons at the University of Surrey Ion Beam Center, UK. The structural modifications in the proton irradiated Makrofol samples have been studied as a function of fluence using different characterization techniques such as X-ray diffraction, thermogravimetric analysis, differential thermal analysis and color difference studies. The proton irradiation in the fluence range led to a more compact structure of Makrofol polymer, which resulted in an improvement in its thermal stability with an increase in the activation energy of thermal decomposition. The melting temperature of the polymer, , was investigated to probe the crystalline domains of the polymer. At a fluence range of , the defect generated destroys the crystalline structure, thereby reducing the melting temperature. Further, the transmission of these samples in the wavelength range of , as well as any color changes, was studied. The color intensity was greatly increased with increasing the proton fluence, and was accompanied by a significant increase in the red and yellow color components. [Copyright &y& Elsevier]

Hydrogels are attracting carriers for immobilization of small molecules due to their excellent properties, such as low optical background, recyclable and high loading ability. Several advantages will be found in designing optical sensors by utilizing hydrogels, such as the convenience for operation, the easiness to separate from media and the difficulties to introduce impurities to detection environment. As a fluorescein-based sensor for Hg2+, the N-(Fluorescein) lactam-N′-methylethylidene (FLA) was synthesized, and the structure confirmation process was finished by 1H NMR, 13C NMR, FT-IR and mass spectrometry. The interaction of FLA with various mental ions demonstrated the high selectivity to Hg2+, which was proved by UV–Vis and fluorescence spectrometry analysis. Meanwhile, the binding mode of FLA Hg2+ was characterized by FT-IR, 1H NMR and UV–Vis spectrophotometry. Then, counting FLA as functional monomer and MBA as crosslinker, different proportions of acrylamide (AAm), 2-hydroxyethyl methacrylate (HEMA) and methyl methacrylate (MMA) were copolymerized with FLA and N , N ′-methylenebisacrylamide (MBA) to prepare hydrogel sensors. The hydrogel sensor was characterized by colorimetry and swelling properties. At last, the prepared hydrogels is capable to respond to different colors of Hg2+ in water or DMSO, and it can be reused after the treatment with ethylenediamine (EDA) solution. (a) Changes of color of Gel 1 in the presence of Hg2+ in distilled water and DMSO. (b) The reuse process of hydrogel sensor. Unlabelled Image • Fluorescein-based sensor • Hg2+ ion selective • Fluorescein-immobilized optical hydrogels • Naked-eye hydrogel sensor • Reusable hydrogel sensor [ABSTRACT FROM AUTHOR]