Effect of Octene Block Copolymer (OBC) and High-Density Polyethylene (HDPE) on Crystalline Morphology, Structure and Mechanical Properties of Octene Random Copolymer.

Blending octene random copolymer (ORC) with other polymers is a promising approach to improving ORC mechanical properties, such as tensile strength and elongation. In this study, octene block copolymer (OBC) with lower density than ORC and high-density polyethylene (HDPE) were used to blend with ORC. The effect of both OBC and HDPE on ORC was analyzed using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and small-angle X-ray scattering (SAXS). For ORC/OBC blends, a small amount of OBC can improve the crystallization ability of ORC. Meanwhile, for ORC/HDPE blends, the crystallization ability of ORC was significantly suppressed, attributed to good compatibility between ORC and HDPE as indicated by the homogeneous morphology and the disappearance of the α transition peak of ORC in ORC/HDPE blends. Therefore, the tensile strength and elongation of ORC/HDPE blends are significantly higher than those of ORC/OBC blends. For ORC/OBC/HDPE ternary blends, we found that when ORC:OBC:HDPE are at a ratio of 70:15:15, cocrystallization is achieved. Although HDPE improves the compatibility of ORC and OBC, the three-phase structure of the ternary blends can be observed through SAXS when HDPE and OBC exceed 30 wt%. Blending HDPE and OBC (≤30 wt%) could improve the mechanical property of ORC.

Effects of Ethylene-Propylene-Diene Monomers (EPDMs) with Different Moony Viscosity on Crystallization Behavior, Structure, and Mechanical Properties of Thermoplastic Vulcanizates (TPVs).

Moony viscosity of ethylene-propylene-diene monomers (EPDMs) can have effect on the crystallization dynamics, structure, and properties of EPDM/polypropylene (PP)-based thermoplastic vulcanizates (TPVs). TPVs with two different Moony viscosities are prepared via a twin-screw extruder, respectively. Crosslinked EPDM with lower Moony viscosity has a higher crosslinking density and the nucleation effect of its crosslink point improves the crystallization ability of PP in TPV, leading to PP phase crystallization at higher temperatures. For TPV with an EPDM of higher Moony viscosity, it has higher crystallinity and the EPDM phase crystallized earlier. Synchrotron radiation studies show that the EPDM with low Moony viscosity has no obvious crystalline structure, and the prepared TPV has an obvious phase separation structure, while the TPV with higher Mooney viscosity of the EPDM does not exhibit obvious phase separation, indicating that the longer EPDM chains have better compatibility with PP in TPV, also evidenced by the almost disappearance of the PP glass transition peak in TPV, from the dynamic mechanical analysis. The longer EPDM chains in TPV provide more physical entanglement and better interaction with PP molecules, resulting in a stronger strain hardening process, longer elongation at break, and higher tensile stress in TPV.

Epidemiological characteristics of multi-drug resistant tuberculosis and pre-extensively drug resistant tuberculosis in Changsha, 2018-2021 / 中国热带医学

@#Abstract: Objective　To understand the situation of drug-resistant tuberculosis screening and epidemiological characteristics of multi-drug resistant tuberculosis (MDR-TB) and pre-extensively drug resistant tuberculosis (pre-XDR-TB) in Changsha, in order to provide a scientific basis for improving the quality of drug-resistant tuberculosis prevention and control in the city. Methods　Demographic information and drug susceptibility date of etiologically positive pulmonary tuberculosis patients in Changsha from 2018 to 2021 were collected, the successful rate of resistance screening, incidence and tendency in MDR-TB and pre-XDR-TB in patients included in this study were statistically analyzed accordingly. 　　Results From 2018 to 2021, the successful screening rates were 86.2%, 87.7%, 81.9% and 71.5% for MDR-TB and 82.2%, 84.8%, 76.9% and 68.2% for pre-XDR-TB, respectively. In each year, MDR-TB patients identified accounted for 7.6% (101/1 222), 6.5%(124/1 774), 6.6%(110/1 555) and 6.3%(99/1 478), and pre-XDR-TB patients identified accounted for 3.6%(46/1 219), 3.8%(69/1 766), 4.4%(69/1 495) and 4.6%(69/1 436), correspondingly. The incidence of MDR-TB showed a slowly downward trend, while the incidence of pre-MDR-TB showed a slowly upward trend, with neither decreasing nor increasing trends being statistically significant (（χ2=1.947，0.806，P>0.050). The incidence of MDR-TB in the retreatment failure population was 66.6% (2/3), and the others, failure initial treatment and recrudescence populations were 23.5% (19/81), 16.7% (2/12) and 15.2% (70/461), respectively. Similar to the incidence above, the incidence of pre-XDR-TB was 16.7% (2/12) among patients who failed in initial treatment, and 12.2% (9/74), 9.8% (43/439), and 4.5% (2/44) among the others, recrudescence and returned patients, respectively. The incidence rates of MDR-TB and pre-XDR-TB in different populations were significantly different (χ2=117.600，59.030，P<0.05). Conclusions There are still areas for improvement in tuberculosis drug resistance surveillance system in Changsha. On the premise of paying attention to patients in retreatment failure, other, initial treatment failure and relapse patients, high sensitivity molecular drug susceptibility testing, and scientifically efficient screening strategies must be explored.

Single base substitution in OsCDC48 is responsible for premature senescence and death phenotype in rice.

A premature senescence and death 128 (psd128) mutant was isolated from an ethyl methane sulfonate-induced rice IR64 mutant bank. The premature senescence phenotype appeared at the six-leaf stage and the plant died at the early heading stage. psd128 exhibited impaired chloroplast development with significantly reduced photosynthetic ability, chlorophyll and carotenoid contents, root vigor, soluble protein content and increased malonaldehyde content. Furthermore, the expression of senescence-related genes was significantly altered in psd128. The mutant trait was controlled by a single recessive nuclear gene. Using map-based strategy, the mutation Oryza sativa cell division cycle 48 (OsCDC48) was isolated and predicted to encode a putative AAA-type ATPase with 809 amino-acid residuals. A single base substitution at position C2347T in psd128 resulted in a premature stop codon. Functional complementation could rescue the mutant phenotype. In addition, RNA interference resulted in the premature senescence and death phenotype. OsCDC48 was expressed constitutively in the root, stem, leaf and panicle. Subcellular analysis indicated that OsCDC48:YFP fusion proteins were located both in the cytoplasm and nucleus. OsCDC48 was highly conserved with more than 90% identity in the protein levels among plant species. Our results indicated that the impaired function of OsCDC48 was responsible for the premature senescence and death phenotype.

[Ecological stability on biological removal of iron and manganese filter under poor nutritional conditions].

To supply necessary bacteria and available nutrients, a method of returning backwashing wastewater to the bio-filter for removal of iron and manganese was used. The ecological stability of bio-filter was investigated from 3 aspects: iron and manganese removal efficiency, micro-ecological characteristics and the quantity distribution of dominant bacteria. The results indicated that, the bio-filter held strong antishock loading capability, when the system was operated at high filtration rate (10-13.9 m/h) and high manganese concentration (3.5-4.5 mg/L), a removal rate more than 98.9% of iron and manganese was achieved. Iron and manganese oxidizing bacteria are the dominant microflora in biological filtering layer, they not only adhere on filter sand materials (4.3 x 10(6) MPN/mL) to form compact biofilm, but also exist among filter materials void (6.5 x 10(6) MPN/mL) to form suspended flocs, which is very important to complete removal of iron and manganese. In the past 5 years, the bio-filter realized a continuous and stable operation and kept a high removal efficiency of iron and manganese without adding any nutrients.