In situ fibre‐reinforced composite films of poly(lactic acid)/low‐density polyethylene blends: effects of composition on morphology,transport and mechanical properties

This study aimed to investigate the effects of blend composition on packaging‐related properties of poly(lactic acid) (PLA) and low density polyethylene (LDPE) blown films. Blend films with PLA contents of 5–20 wt% were produced and compared. Scanning electron micrographs of cross‐sectional cryofractured surfaces of the blend films revealed that in situ fibre‐reinforced composites were obtained. Viscosity ratio of the polymer components of ca 1 confirmed that fibre formation was favourable for this blend system. PLA microdomains were dispersed throughout the film in forms of long fibres (length‐to‐diameter ratio > 100) and ribbons. The number of fibres and ribbons increased with an increase of PLA content. Critical content of PLA was found to be 20 wt% for effective improvement of both moduli and gas barrier properties. Incorporation of poly[ethylene‐co‐(methyl acrylate)] compatibilizer showed minimal effect on PLA structure. However, it did improve moduli and O₂ barrier properties when sufficient amount (1.5 pph) was used in 10 wt% PLA/LDPE. In short, flow behaviour, ratio of polymer components and degree of compatibility together played intricate roles in the morphology and hence mechanical and transport properties of PLA/LDPE immiscible blends. © 2017 Society of Chemical Industry     

Antioxidants alleviate electric field-induced effects on lung tissue based on assays of heme oxygenase-1, protein carbonyl content, malondialdehyde, nitric oxide, and hydroxyproline

In order to test whether antioxidants have beneficiary effects on electric field induced damage, we determined the pulmonary levels of heme oxygenase-1 (HO-1), protein carbonyl content (PCO), malondialdehyde (MDA), nitric oxide (NO) and hydroxyproline (HP) under extremely low frequency (ELF) electric (E) field exposure (50 Hz, 12 kV/m, 7 days/for 8 h/day). While PCO levels significantly increased (p < 0.05), insignificant changes (p > 0.05) were observed in HO-1, MDA, NO and HP levels for electric field exposure groups compared to the control group. We have not observed any significant change in these parameters on the electric field group compared to the group where NAC and EGCG were separately applied along with electric field. However, during our previous studies, we have concluded that NAC and EGCG are potent antioxidants and we believe that new studies should be established by way of setting up different experimental conditions.     

Effect of TiO2/adsorbent hybrid photocatalysts for toluene decomposition in gas phase

12 hybrid photocatalysts consisting of titania (TiO₂) and an adsorbent such as mordenite were investigated for the photocatalytic decomposition of toluene, a major indoor contaminant in indoor air. The highest decomposition rate was obtained with the use of mordenite and silicon dioxide (SiO₂) as additives to TiO₂. The photocatalytic activities of hybrid photocatalysts in decomposing toluene are 1.33 times as high as pure P25 at the net weight loading of 0.49 mg/cm² under the test condition. Scanning electron microscopy (SEM) images confirmed that the hybrid photocatalyst films were very porously distributed; TiO₂ was adsorbed on the surface of mordenite and SiO₂, increasing the reaction area of TiO₂. The unimolecular Langmuir–Hishelwood model and mass-transfer-based (MTB) method were used to evaluate the reaction coefficients and adsorption equilibrium coefficients of hybrid photocatalysts. It is evidenced that the reaction areas of two hybrid photocatalysts were 1.52 and 1.64 times larger than that of P25, respectively, which is the major reason to make the high removal efficiency of toluene.     

A SIMPLIFIED ALGORITHM FOR COMPUTING THE VARIATION IN OXYHEMOGLOBIN SATURATION WITH pH, PCO2, T AND DPG

We have modified a model for the oxyhemoglobin equilibrium curve (OHEC) and developed an algorithm for which the nonstandard OHEC can be computed. The model requires 2 parameters and a scaling factor (S_m.) The model parameters are: P*, the oxygen partial pressure where the slope of the OHEC is at its maximum, and a rate parameter K. We estimated P* = 2.76 ± 0.04 SE kPa and K = 0.544 ±0.044 (SE) kPa^-1 from ten previous literature reports for the human OHEC at standard conditions (T = 37°C, pH = 7.4, PCO² = 5.33kPa and the molar concentration ratio [DPG7sol;Hb] = 0.9). We also determined how P* and K vary under nonstandard conditions by comparing the modified model with two previous nonstandard OHEC algorithms in the literature. These variations can be characterized by an additional 4 parameters. The dimensionless parameter product KP* was found to be relatively insensitive to deviations from standard conditions. We propose a new algorithm for the nonstandard OHEC which requires a total of 7 parameters, is simpler to implement and is computationally more efficient than other algorithms we investigated.     

Disinfection of Legionella pneumophila by photocatalytic oxidation

Photocatalytic oxidation (PCO) was proven to be efficacious in the inactivation of Legionella pneumophila serogroup 1 Strains 977, 1009, 1014 and ATCC 33153. The local (Strains 997, 1009 and 1014) and ATCC (Strain 33153) strains showed sensitivity differences towards PCO. The inactivation mechanisms of PCO were investigated by transmission and scanning electron microscopy by which PCO was found to disintegrate the cells eventually. Before the disintegration, there was lipid peroxidation of outer and cytoplasmic membrane causing holes formation and leading to the entry of OH into the cells to oxidize the intracellular components. Fatty acid profile analysis found that the amount of saturated, 16-carbon branched-chain fatty acid, which is predominant in Legionella, decreased in the surviving populations from PCO. A relationship between the amount of this fatty acid and the PCO sensitivity of the tested strains was also observed. Mineralization of cells by PCO was proven by total organic carbon analysis.     

Photocatalytic effect on plasmid DNA damage under different UV irradiation time

Microbiological contaminants such as mold and mould (both of them fungi), pathogenic bacteria, viruses that widely exist in indoor environment can cause respiratory allergic reactions, asthma, and infectious diseases ranging from influenza to Legionnaires disease. Photocatalytic oxidation (PCO) by TiO₂ is a technology that can decompose a wide range of chemical pollutants and disinfect microbiological contaminants by utilizing a semiconductor catalyst such as TiO₂ and near-UV (ultraviolet) radiation. In this research, a solution of supercoiled plasmid DNA was used to demonstrate photodynamic DNA strand-breaking and hydroxylation activity at photocatalyst surfaces. Index of DNA damage degree induced by a commercial TiO₂ and a non-commercial nanocatalyst were compared, with the UV irradiation time as the controlled variable. Results show that as irradiation time increased, the photocatalytic effect on DNA also increased, and the nanocatalyst has a better photocatalytic effect on plasmid DNA than P25 under the same test conditions. For the irradiation time as short as five seconds, plasmid DNA damage occurred. This fundamental research provides quantitative information for further evaluation of PCO in destructing microbiological pollutants.     

Photoinduced superhydrophilicity and photocatalytic properties of ZnO nanoplatelets

The present work is devoted to the investigation of photoinduced superhydrophilicity (PSH) and photocatalytic oxidation (PCO) activity of quasi-2D zinc oxide nanoplatelets obtained by Chemical Vapor Deposition (CVD). In the case of PCO, the degradation of a fatty compound layer (methyl stearate) was chosen as a test reaction. The peculiar textural and morphological features of such systems resulted in a PSH behavior and in a PCO activity appreciably higher than those of a reference commercial Pilkington^® Activ^TM Glass. Relevant results are presented and discussed as a function of the structure and morphology of these systems, whose control enables a direct tailoring of the functional response.     

Determination and risk assessment of by-products resulting from photocatalytic oxidation of toluene

The generation of harmful by-products during photocatalytic oxidation (PCO) of volatile organic compounds (VOCs) is a bottleneck problem for the application of PCO technology in indoor environment. Toluene is a typical VOC found in indoor air. In this work, the by-products at ppb level were studied during PCO decomposition of toluene in a plate-type reactor and identified using PTR-MS (proton transfer reaction-mass spectrometry) and GC–MS (gas chromatography–mass spectroscopy). The results indicated that benzaldehyde, methanol, acetaldehyde, acetone/propionaldehyde, formic acid/ethanol and acetic acid were the main by-products in the gas phase. By adjusting the concentration of water vapor, some compounds adsorbed on the TiO₂ surface were ascertained, which resulted in the deactivation of TiO₂. They were benzoic acid, benzene, acrylaldehyde, butyraldehyde and pentanal. Some of these by-products have not been reported in the literature. Possible photocatalytic oxidation pathways of toluene were proposed. A health-related index (HRI) was introduced to assess the risk level to human health of these ppb-level by-products. It concludes that although some undesired by-products (even carcinogenic) are generated during PCO decomposition of toluene, it seems that these by-products do not have negative effects to human health because of their low concentrations.     

Protective effects of four Iranian medicinal plants against free radical-mediated protein oxidation

The role of oxidative protein damages in the pathophysiology of human diseases is currently a topic of considerable interest as oxidised proteins has been implicated in a wide spectrum of clinical disorders. In this study, the antioxidant activities of four Iranian medicinal plants, namely Teucrium polium, Cyperus rotundus, Anethum graveolens and Nasturtium officinale against metal–catalysed protein oxidation were evaluated by pro-oxidant model (Fe²⁺/ascorbate) in rat liver homogenates. The addition of Fe²⁺/ascorbate to the liver homogenate significantly increased the extent of protein oxidation, such as protein carbonyl (PCO) formation and loss of protein-bound sulphydryl (P-SH) groups. Furthermore, the rates of reactive oxygen species (ROS) formation and lipid peroxidation (LPO) were also increased. The plant extracts showed inhibitory effects against PCO formation, P-SH oxidation, ROS formation and LPO to varying degrees. Based on this study, the order of antioxidant activity against protein oxidation was found to be: T. polium > C. rotundus > A. graveolens > N. officinale. The protective effects of each plant extract could be due to its polyphenolic content. In that respect, the T. polium extract with highest polyphenolic content has more antioxidant activity against protein oxidation.