Influence of morphology on photo‐degradation of low density polyethylene films

The effect of the morphology on photo‐degradation was investigated for low‐density polyethylene materials. For this purpose, films with different degrees of crystallinity and different degrees of orientation were prepared. For all the films, photodegradation was promoted at 336K for 12 days using a weather meter. The following results were obtained. There existed an induction period before degradation or chain scission. The induction period was longer for stretched films than for un‐stretched ones. Also, the rate of degradation became lower for stretched films. However, both the induction period and the rate of degradation hardly changed with heat‐treatment condition, that is, the degree of crystallinity. In the induction period, the density changed in a complicated manner. This complicated change must be due to the change in the molecular aggregation state of the amorphous phase. The rheological and GPC measurements indicated that photo‐degradation causes the lowering of molecular weight and the increase in higher molecular weight fraction, and consequently the broadening of molecular weight distribution. The lowering of molecular weight may be caused by chain scission and the increase in higher molecular weight fraction by the formation of crosslinks.     

Chemical stability enhancement and cytotoxicity reduction of papain loaded in PLGA nanospheres

Poly(lactic-co-glycolic acid) (PLGA) nanospheres loaded with papain were prepared by the emulsion solvent diffusion in water (ESD) and the w/o/w emulsion solvent evaporation (ESE) methods. The nanosphere loaded with papain from the ESE method gave smaller particle sizes (220–232?nm) and higher encapsulation efficiency of about two-folds than those from the ESD method. The morphology of the nanospheres loaded with papain prepared by the ESE method exhibited spherical shape and smooth surface investigated by SEM and TEM. The release profile of papain from the PLGA nanospheres of the ESD and ESE method indicated two phases with an initial rapid phase of 6?h and followed by the slow release phase of 48?h. The unloaded PLGA nanospheres from the two methods did not show any cytotoxicity in human skin fibroblasts, while the unloaded papain gave toxicity more than the loaded papain of 1.5 times. Papain loaded in PLGA nanospheres prepared by the ESE method was more chemical stable than the unloaded papain of eight and three times when kept at 4°C and 25°C for 6 weeks, respectively. The developed stable and low cytotoxic nanosphere loaded with papain can be further developed as topical products.     

Flavonoid Nobiletin Attenuates Cyclophosphamide-Induced Cystitis in Mice through Mechanisms That Involve Inhibition of IL-1β Induced Connexin 43 Upregulation and Gap Junction Communication in Urothelial Cells

Bladder inflammatory diseases cause various urinary symptoms, such as urinary frequency and painful urination, that impair quality of life. In this study, we used a mouse model of cyclophosphamide (CYP)-induced bladder inflammation and immortalized human urothelial (TRT-HU1) cells to explore the preventive potential of nobiletin (NOB), a polymethoxylated flavone enriched in citrus fruit peel, and investigate its mechanism of action in the bladder. Prophylaxis with PMF90 (60% NOB) attenuated the development of bladder inflammation and urinary symptoms in CYP-treated mice. PMF90 also reduced the upregulation of connexin 43 (Cx43), a major component of gap junction channels, in the bladder mucosa of CYP-treated mice. Stimulation of TRT-HU1 cells with the pro-inflammatory cytokine IL-1β increased Cx43 mRNA and protein expression and enhanced gap junction coupling—responses that were prevented by pre-treatment with NOB. In urothelium-specific Cx43 knockout (uCx43KO) mice, macroscopic signs of bladder inflammation and changes in voiding behavior induced by CYP treatment were significantly attenuated when compared to controls. These findings indicate the participation of urothelial Cx43 in the development of bladder inflammation and urinary symptoms in CYP-treated mice and provide pre-clinical evidence for the preventive potential of NOB through its anti-inflammatory effects on IL-1β signaling and urothelial Cx43 expression.     

Improvement of a Real Gas-Sensor for the Origin of Methane Selectivity Degradation by µ-XAFS Investigation

Nano-Micro Letters - We have directly investigated the chemical state of the Pd species in a real μ-gas sensor device by examining the μ-fluorescence X-ray absorption fine structure. The...     

Failure-tolerant performance stabilization of the generic large-scale system by decentralized linear output feedback

Most of the existing results on the decentralized stabilization of large-scale systems consider systems in the input-output-decentralized form, i.e., systems whose input and output matrices are block diagonal. The controller synthesis for such systems is less involved than that for input-output-centralized ones. In this paper, a transformation is proposed for the input-output decentralization of the generic large-scale system. Using the transformed system, a sufficient condition for failure-tolerant performance stabilization of the original large-scale system in a desirable performance region under decentralized linear output feedback is established. The problem is then reformulated as a constrained nonlinear optimization problem. The proposed methodology results in the optimal reconciliation of failure-tolerant performance stabilization of the overall system, and reliability and low actuator gains of the isolated subsystems. The effectiveness of the proposed approach is demonstrated by an example.     

Effects of Heating Rate on Stress Evolution in Alkoxide-Derived Silica Gel-Coating Films

Silica gel films were deposited by spin coating on single-crystal Si wafers using an acid-catalyzed Si(OC₂H₅)₄ solution as a coating solution. The gel films were heated at various rates, where in situ stress measurement was conducted. In-plane tensile stress developed during the course of heating, and was found to be larger at lower heating rates at temperatures up to 350°C. The larger stress was thought to cause cracking at lower temperatures, which was previously observed at lower heating rates in in situ observation. The larger stress at lower heating rates was basically ascribed to the larger degrees of densification, which was revealed in the larger extent of reduction in thickness as well as in Si–OH/Si–O–Si and O–H/Si–O–Si infrared absorption band area ratios at lower heating rates. The difference in stress at different heating rates appeared to originate mainly in the difference observed at low temperatures below 130°C, suggesting that the heating rate particularly affects the densification that occurs via solvent evaporation. The increment in stress was reduced over 400°C when the heating rate was low, which was thought to result from the higher degree of densification already achieved below 400°C as well as the structural relaxation occurring at such high temperatures.     

Efficient global optimization applied to wind tunnel evaluation-based optimization for improvement of flow control by plasma actuators

A kriging-based genetic algorithm called efficient global optimization (EGO) was employed to optimize the parameters for the operating conditions of plasma actuators. The aerodynamic performance was evaluated by wind tunnel testing to overcome the disadvantages of time-consuming numerical simulations. The proposed system was used on two design problems to design the power supply for a plasma actuator. The first case was the drag minimization problem around a semicircular cylinder. In this case, the inhibitory effect of flow separation was also observed. The second case was the lift maximization problem around a circular cylinder. This case was similar to the aerofoil design, because the circular cylinder has potential to work as an aerofoil owing to the control of the flow circulation by the plasma actuators with four design parameters. In this case, applicability to the multi-variant design problem was also investigated. Based on these results, optimum designs and global design information were obtained while drastically reducing the number of experiments required compared to a full factorial experiment.     

Photoluminescence properties of a hollandite compound K2Ga2Sn6O16

A hollandite compound K₂Ga₂Sn₆O₁₆ (KGSO) has photocatalytic activity, although little is known about the optical properties of the compound. To design a higher quality photocatalyst, studies on its optical properties are required. In this study, a KGSO powder and a SnO₂ (rutile structure) powder were prepared by the sol—gel method. Photoluminescence (PL) and PL excitation spectra of the two powders were measured. To our knowledge, this is the first report of PL from a hollandite compound. It was found that the band gap energy of the KGSO powder is 3.6 eV, the value of which is identical with that of the band gap energy of SnO₂. This was confirmed by the result of the photoacoustic spectrum of the KGSO. The shapes of the PL excitation spectra of the two powders agreed. Moreover, the PL spectra of the two powders have one broad band around 600 nm. From these results, one can conclude that the mechanism of PL of KGSO is the same as that of SnO₂. In air with ethanol, however, the time-course of the KGSO powder was different from that of the SnO₂ powder. By adding ethanol vapor in air, the PL intensity of the SnO₂ powder increased, whereas the PL intensity of the KGSO powder remained unchanged. By comparing the PL time-courses of the two powders with those of a commercial rutile TiO₂ powder, it was concluded that the photodesorption of O₂ in air with ethanol occurs on the SnO₂ powder, not on the KGSO powder. This was supported by the results of the inorganic carbon concentrations on the two powders. These results indicate that the behavior of O₂ on the KGSO surface during a photocatalytic oxidation is different from that on the SnO₂ surface during the oxidation.

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