Structure evolution of polyamide (11)’s crystalline phase under uniaxial stretching and increasing temperature

Abstract

Thermal processing of polyamide influences the internal crystalline structure and thereafter the post product mechanical performance. In this article, the crystalline transition of polyamide-11 (PA11) plate under uniaxial stretching and increasing temperature was investigated systematically using in-situ synchrotron X-ray technique. It was discovered that the lamellar slippage, fragmentation and recrystallization occurred in sequence under increasing temperature. In detail, the crystal of PA11 plate was stretched with a transition from triclinic α-form to mesomorphic phase at 25 °C. For the thermally activated γ-form crystals, crystal transition was inhibited when temperature was increased up to 160 °C. The melt-recrystallization was inclined to take place at large tensile strains. This work enhances the research significance of the thermal processing of polyamide and provides a theoretical method to improve the high performance of polyamide products.

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Green synthesis process and properties of polyurethane completely using ethanol as solvent

Abstract

It is a challenge to simultaneously retain high performance and green synthesis process of polyurethane (PU). Here, a PU was synthesized completely using ethanol as solvent based on the chain extender, hexanediamine (HMD), with higher reactivity towards isocyanate groups than ethanol. Chemical components in PU prepared by a green process (GPU) were characterized by Fourier Transform Infrared Spectroscopy (FTIR). Molecular weight and its distribution of GPU were characterized by Gel Permeation Chromatography (GPC). Mechanical properties and thermal-mechanical properties of GPU were characterized by Electronic Tensile Testing Machine and Dynamic Thermomechanical Analysis (DMA) separately. The glass transition temperature (Tg) and thermal stability of GPU were characterized by Differential Scanning Calorimeter (DSC) and Thermogravimetric Analysis (TGA). Results showed that this GPU presented superior mechanical properties of 61.4 MPa and low saturated water absorption of 6.6% compared with conventional solvent-based PU and waterborne PU whose synthesis process contained some toxic organic solvent.

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A Short Term Comparison of Cartilage with Temporalis Fascia Graft Tympanoplasty in Paediatric and Adolescent Population

Abstract

To compare the anatomic and functional outcomes of the cartilage and temporalis fascia graft materials in type 1 tympanoplasty in paediatric and adolescent population. A total of 55 patients aged <18 years who required type 1 tympanoplasty were selected. 30 patients underwent cartilage palisade tympanoplasty and 25 using temporalis fascia grafts. The age, the side of the operated ear, the operative technique, pre- and post operative pure tone and impedance audiological results, and the status of the graft were noted. Graft was considered taken up if there was successful closure of tympanic membrane perforation. At the end of 6 months, the graft take rate for cartilage was 90% and for temporalis fascia it was 80% (p > 0.05). ABG closure ratio in cartilage group was 58.54 ± 23.10% and in temporalis fascia group was 56.46 ± 27.4% (p > 0.05). Pre operatively all patients had type B tympanogram in both the groups. While post operatively either type A or C curve was seen in 80% patients of cartilage and 68% patients of temporalis fascia group. Hearing outcomes and graft success rates were high in both fascia and cartilage graft groups but not significantly different.

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Surgical Outcome of Mastoid Cavity Obliteration Using Postauricular Composite Bone with Periosteum Flap

Abstract

This study was aimed to evaluate surgical outcome of patients undergoing obliteration of mastoid cavity with postauricular composite osteo-periosteal flap. This interventional study was carried out on 100 patients having unsafe CSOM from Nov. 2012 to Oct. 2014 who underwent canal wall down mastoidectomy with tympanoplasty and obliteration of cavity using composite osteo-periosteal flap. The primary outcome measure was control of suppuration and creation of dry, low-maintenance mastoid cavity, which was assessed using Merchant et al. grading system. At the end of 1 year follow-up, 89% patients had Grade 0 summary score while Grade 3 which was considered as failure of control of infection was not obtained in any patient during the entire follow-up period. Mastoid cavity obliteration using composite osteo-periosteal flap is an effective technique to avoid cavity problems.

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Investigation of relationships between meteorological conditions and high PM 10 pollution in a megacity in the western Yangtze River Delta, China

Abstract

Nanjing, a megacity in the western Yangtze River Delta of China, has been suffering high PM₁₀ pollution during recent decades. The meteorological conditions that affect the formation of high PM₁₀ pollution in Nanjing remain unknown. In this study, 12-year daily PM₁₀ concentrations and ground-level meteorological conditions from 2001 to 2012 were analyzed. The relationships between PM₁₀ concentrations and meteorological parameters including wind direction, wind speed, temperature, relative humidity, and precipitation were investigated with multiple methods, including occurrence frequency, back trajectory, multiple linear regression (MLR), and artificial neural network (ANN) analysis. The results show that PM₁₀ pollution in Nanjing was severe during 2001–2012. The 12-year mean is 109 μg/m³, which is 56% higher than the grade II annual PM₁₀ standard of China. Declining trends are found for both the annual averages and the episode averages during the most polluted events, with a rate of 3.5 and 4.0 μg/m³ per year, respectively. High PM₁₀ pollution events are more likely to occur on no-precipitation days when wind is from east with speed of 1.0 to 3.0 m/s, temperature is 10 to 20 °C, relative humidity is below 80%, and sea-level pressure is 1015–1025 hPa. The 72- and 24-h back trajectory analysis shows that over half of the air masses on the high PM₁₀ pollution days are from east-south with an average transport distance of around 400 km in 72 h and 200 km in 24 h, respectively. Including the previous day concentration in the MLR models substantially improves model performance for predicting daily PM₁₀, with an increase of the Pearson correlation coefficient from 0.25 to 0.61. The ANN model generally performs better than the MLR models and can be considered as a better method for future PM₁₀ forecasting. However, both models have difficulties accurately predicting very severe pollution events, and more factors should be considered in future studies.

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Placing negative multi-gene panel results into clinical context

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Iron and thiol redox signaling in cancer: An exquisite balance to escape ferroptosis

Publication date: July 2017
Source:Free Radical Biology and Medicine, Volume 108
Author(s): Shinya Toyokuni, Fumiya Ito, Kyoko Yamashita, Yasumasa Okazaki, Shinya Akatsuka
Epidemiological data indicate a constant worldwide increase in cancer mortality, although the age of onset is increasing. Recent accumulation of genomic data on human cancer via next-generation sequencing confirmed that cancer is a disease of genome alteration. In many cancers, the Nrf2 transcription system is activated via mutations either in Nrf2 or Keap1 ubiquitin ligase, leading to persistent activation of the genes with antioxidative functions. Furthermore, deep sequencing of passenger mutations is clarifying responsible cancer causative agent(s) in each case, including aging, APOBEC activation, smoking and UV. Therefore, it is most likely that oxidative stress is the principal initiating factor in carcinogenesis, with the involvement of two essential molecules for life, iron and oxygen. There is evidence based on epidemiological and animal studies that excess iron is a major risk for carcinogenesis, suggesting the importance of ferroptosis-resistance. Microscopic visualization of catalytic Fe(II) has recently become available. Although catalytic Fe(II) is largely present in lysosomes, proliferating cells harbor catalytic Fe(II) also in the cytosol and mitochondria. Oxidative stress catalyzed by Fe(II) is counteracted by thiol systems at different functional levels. Nitric oxide, carbon monoxide and hydrogen (per)sulfide modulate these reactions. Mitochondria generate not only energy but also heme/iron sulfur cluster cofactors and remain mostly dysfunctional in cancer cells, leading to Warburg effects. Cancer cells are under persistent oxidative stress with a delicate balance between catalytic iron and thiols, thereby escaping ferroptosis. Thus, high-dose L-ascorbate and non-thermal plasma as well as glucose/glutamine deprivation may provide additional benefits as cancer therapies over preexisting therapeutics.

Graphical abstract

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