Interplay between bulk viscoelasticity and surface energy in autohesive tack of rubber‐tackifier blends

The effects of change in surface energy and bulk viscoelastic properties on the autohesive tack strength of brominated isobutylene‐co‐p‐methylstyrene (BIMS) rubber have been investigated by the addition of hydrocarbon resin (HCR) tackifier and maleated hydrocarbon resin (MA‐g‐HCR) tackifier. The addition of compatible HCR tackifier results in a reasonable increment in the tack strength of BIMS rubber by modifying only the bulk viscoelastic properties (compliance, entanglement molecular weight, relaxation time, self‐diffusion, and monomer friction coefficient values) of BIMS rubber to perform better during the course of bonding and debonding steps of the peel test. Incorporation of MA‐g‐HCR tackifier (containing 5–20 wt % of grafted maleic anhydride) steadily increases the tack strength of BIMS rubber further by precisely modifying both the surface energy and bulk viscoelastic properties to perform much better in the bonding and debonding steps. However, beyond 20 wt % of grafted maleic anhydride in the HCR tackifier, the tack strength starts decreasing due to the incompatibility between the blend components, and hence, the bulk viscoelastic properties required for bond formation are severely retarded by the interrelated reinforcing effect and the phase separation effect of the brittle MA‐g‐HCR tackifier in the BIMS rubber. Hence, the polar groups in a tackifier will contribute to significant enhancement of autohesive tack strength only if the bulk viscoelastic property of the rubber‐tackifier blend is favorable for bond formation and bond separation. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 972–982, 2010     

Digestive process of the raptorial feeder ciliate Litonotus lamella (Rabdophora, Litostomatea) visualized by fluorescence microscopy

In this paper we present a fluorescence microscopy investigation of the digestive process of Litonotus lamella, which we used as a prototype of the raptorial feeding behaviour. The sequence of its digestive processes, from the capture of the prey (Euplotes crassus) to the formation of digestive vacuoles was evidenced using Acridine Orange, a high quantum yield fluorescent vital probe which has a great affinity with the acid vesicle compartments. Acid vesicle localization and displacement during digestion consisted of the following phases: in starved Litonotus vesicles were localized in the neck of the ciliate; after the capture, they were displaced around the vacoule containing the prey in early digestiion, whereas in advanced digestion tens of digestive vacuoles containing Euplotes fragments were spread over the body of the predator; 1 h after capture, the digestive process was complete, and acid vesicles reorganized in the neck of the predator. The most important feature we observed was that the digestive process occurred not in the single phagosome as in filter feeder ciliates, such as Paramecium, but in many digestive vacuoles scattered all over the predator cytoplasm, which asynchronously digest prey fragments.     

Surface‐enhanced Raman scattering characteristics of CuO : Mn/Ag heterojunction probed by methyl orange: effect of Mn2+ doping

Interest in the synthesis of hybrid substrates for surface‐enhanced Raman scattering (SERS) has surged recently. Hereof, in the present work, a hybrid SERS substrate CuO : Mn/Ag heterojunction has been synthesised. To accomplish this, the nanostructred Ag island film and CuO : Mn nanoparticles are synthesised by vacuum thermal evaporation method and sol–gel method respectively, and thereafter, a heterojunction between the CuO : Mn and Ag is fabricated by adsorption of CuO : Mn (10^‐3 m in ethanol) on Ag island film. Further, the SERS sensitivity of CuO : Mn/Ag heterojunctions has been studied by probing methyl orange. We observed that with Mn‐doping in the lattice of CuO, the SERS signal is enhanced considerably because of ferromagnetic ordering in CuO : Mn. DFT/B3LYP/6‐311 G(d, p) method is used to calculate the energy of HOMO and LUMO level of methyl orange. Copyright © 2016 John Wiley & Sons, Ltd.     

壳聚糖对酸性艳橙GS的吸附平衡与动力学研究

研究了壳聚糖(CS)对水溶液中的酸性艳橙GS(ABO)染料的吸附性能,考察了温度、pH值、壳聚糖分子量对吸附性能的影响.不同温度下的动力学数据分别采用拟一级、拟二级、内扩散方程进行关联;不同温度下壳聚糖对酸性艳橙GS的吸附平衡数据分别用1angmuir、Freundlich、Tempkin模型拟合.结果表明:该吸附过程...     

Ameliorative Effect of Citrus Lemon Peel Extract and Resveratrol on Premature Ovarian Failure Rat Model: Role of iNOS/Caspase-3 Pathway

Premature ovarian failure (POF) is described as a loss of oocytes and the absence of folliculogenesis and is considered an adverse effect of chemotherapeutic drugs, which leads to infertility. Subsequently, the existing inquiry was achieved by exploring the potential suspicious influences of lemon peel extract (LPE), and resveratrol (RES) on cyclophosphamide (CPA) induced-POF. The results showed that CPA-induced POF significantly decreased serum estradiol (E2) and progesterone levels, along with a considerable rise in serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels. Moreover, CPA administration to rats significantly increased the serum level of Malondialdehyde (MDA) and significantly lowered the levels of reduced glutathione (GSH) and superoxide dismutase (SOD); in addition, it increased nuclear factor kappa B (NF-κB) levels, tumor necrosis factor-α (TNF-α), as well as cyclooxygenase 2 (COX-2) with the spread expression of inducible nitric oxide synthase (iNOS) mRNA levels and caspase-3 (Casp3) levels in ovarian tissues versus the control rats. However, treatment with LPE and RES suppressed the triggering of NF- κB pathways, evidenced by a considerable reduction in Casp3 & iNOS mRNA expression level and significant ameliorative effects in all evaluated parameters, as confirmed by the histological and immunohistochemical investigation when comparing the model group. In overall findings, both lemon peel extract and resveratrol can mitigate the adverse effects of CPA-induced POF. Most crucially, its combination therapy is a promising pharmacological agent for this disease.     

Assessment of Cucurbita spp. Peel Extracts as Potential Sources of Active Substances for Skin Care and Dermatology

By-products of cultivated plants are one of the major environmental concerns worldwide. Due to the high concentration of bioactive chemicals, such waste may be considered hazardous due to the interference with the plant growth, deterioration of the drinking water quality or toxic effects on sensitive marine organisms. Moreover, plant-derived by-products, with proper handling, may represent a low-cost source of bioactive compounds potentially important for pharmaceutical and cosmetics industries. The aim of the study was to evaluate the phytochemical composition, antioxidant activity, the influence of tyrosinase activity, in vitro sun protecting factor and cytotoxicity of 15 extracts from peels of five cultivars of Cucurbita maxima and C. moschata. The extracts were prepared using “green solvents” (water, 50% propylene glycol, and 20% ethanol) and ultrasound-assisted extraction. The performed analysis showed that the peel extracts from various cultivars differ significantly in respect to the phytochemical content and activity. The type of solvent also had a significant impact on the extract’s composition and bioactivity. Aqueous peel extracts contained the highest amounts of flavonoids, showed the greatest antioxidant potential and the most significant in vitro SPF values. In vitro studies showed that the analyzed peel extracts are not cytotoxic for human keratinocytes up to the concentration of 1000 µg/mL and thus might be considered as non-irritant for the skin. The study confirms the potential application of peel extracts from Cucurbita spp. cultivars in cosmetic products.     

Cerium Oxide Nanorods Synthesized by Dalbergia sissoo Extract for Antioxidant,Cytotoxicity, and Photocatalytic Applications

In this study, cerium oxide nanorods (CeO₂-NRs) were synthesized by using the phytochemicals present in the Dalbergia sissoo extract. The physiochemical characteristics of the as-prepared CeO₂-NRs were investigated by using ultraviolet-visible spectroscopy (UV-VIS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction analysis (XRD). The SEM and UV-VIS analyses revealed that the acquired nanomaterials possessed a rod-like morphology while the XRD results further confirmed that the synthesized NRs exhibited a cubic crystal lattice system. The antioxidant capacity of the synthesized CeO₂-NRs was investigated by using several in vitro biochemical assays. It was observed that the synthesized NRs exhibited better antioxidant potential in comparison to the industrial antioxidant of the butylated hydroxyanisole (BHA) in 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The biochemical assays, including lipid peroxidation (LPO), total antioxidant capacity (TAC), and catalase activity (CAT), were also performed in the human lymphocytes incubated with the CeO₂-NRs to investigate the impact of the NRs on these oxidative biomarkers. Enhanced reductive capabilities were observed in all the assays, revealing that the NRs possess excellent antioxidant properties. Moreover, the cytotoxic potential of the CeO₂-NRs was also investigated with the MTT assay. The CeO₂-NRs were found to effectively kill off the cancerous cells (MCF-7 human breast cancer cell line), further indicating that the synthesized NRs exhibit anticancer potential as well. One of the major applications studied for the prepared CeO₂-NRs was performing the statistical optimization of the photocatalytic degradation reaction of the methyl orange (MO) dye. The reaction was optimized by using the technique of response surface methodology (RSM). This advanced approach facilitates the development of the predictive model on the basis of central composite design (CCD) for this degradation reaction. The maximum degradation of 99.31% was achieved at the experimental optimized conditions, which corresponded rather well with the predicted percentage degradation values of 99.58%. These results indicate that the developed predictive model can effectively explain the performed experimental reaction. To conclude, the CeO₂-NRs exhibited excellent results for multiple applications.     

Contact-Piezoelectric Bi-Catalysis of an Electrospun ZnO@PVDF Composite Membrane for Dye Decomposition

The treatment of organic pollutants in wastewater is becoming a great challenge for social development. Herein, a novel contact-piezoelectric bi-catalysis of a ZnO@ PVDF composite membrane was prepared by electrospinning technology. The obtained ZnO@PVDF composite membranes is superior to the pure PVDF membrane in decomposing methyl orange (MO) under ultrasonication at room temperature, which is mainly attributed to the synergy effect of the contact-electro-catalysis of dielectric PVDF, as well as the piezoelectric catalysis of tetrapodal ZnO and the β-phase of PVDF. The heterostructure of the piezoelectric-ZnO@dielectric-PVDF composite is beneficial in reducing the electron/hole pair recombination. As compared to the pure PVDF membrane, the catalytic degradation efficiency of the ZnO@PVDF composite membrane was improved by 444.23% under ultrasonication. Moreover, the reusability and stability of the composite membrane are comparable to those of the traditional powdered catalyst. This work offers a promising strategy for improving the pollutant degradation by combining contact-electro-catalysis with piezoelectric catalysis.     

静电自组装制备纳米TiO2/SiO2光催化材料

采用静电自组装方法制备了纳米TiO2/SiO2光催化材料。采用巯丙基三甲氧基硅烷偶联剂对SiO2进行干法改性,采用双氧水/冰醋酸将偶联剂巯基基团氧化为磺酸基基团。在正负电荷的吸引下,带负电荷的SiO2与带正电荷的钛聚合阳离子自发地组装在一起,经一定温度热处理得到纳米TiO2/SiO2光催化材料。采用XRD、FTIR、PL、UV-Vis DRS、SEM和ICP等对材料进行了分析和表征。采用甲基橙溶液评价材料的光催化性能。结果表明:SiO2促使锐钛矿的形成,抑制锐钛矿向金红石的转变,减小TiO2的晶粒尺寸,使得TiO2光吸收波长发生蓝移。TiO2与SiO2通过Si-O-Ti键发生结合。采用静电自组装方法制备的材料中TiO2的含量高于传统方法,导致材料的光催化性能有所提高。     

MoO3-C3N4复合光催化剂的可见光下高效催化降解甲基橙

以钼酸铵和C₃N₄为前驱体,利用浸渍法成功制备了高性能MoO₃-C₃N₄复合光催化剂,利用X射线衍射（XRD）、傅里叶红外（FT-IR）、高分辨电镜（HRTEM）及N₂吸附-脱附曲线等测试手段对所得MoO₃-C₃N₄光催化剂进行了结构和形貌表征。以可见光下光催化降解甲基橙反应表征MoO₃-C₃N₄的光催化活性。实验结果表明,MoO₃-C₃N₄光催化剂具有非常好的光催化降解性能,且MoO₃含量对反应活性产生显著影响。当MoO₃含量为1.6%（w/w）时光催化活性最好,其速率常数达到C₃N₄的50倍。通过研究发现该复合催化剂的高活性来自于其Z型光生载流子传输过程,抑制了光生电子空穴对的复合并延长了引入MoO₃产生的载流子的寿命。