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71.
Sea urchin spines were chosen as a model system for biomimetic ceramics obtained using starch-blended slip casting.Porous alumina ceramics with cap-shaped layers with different alternating porosities were found to have superior fracturebehavior under bulk compression compared to ceramics with uniform porosity.They fail in a cascading manner,absorbing highamounts of energy during extended compression paths.The porosity variation in an otherwise single phase material mimicks thearchitectural microstructure design of sea urchin spines of Heterocentrotus mammillatus,which are promising model materialsfor impact protection.  相似文献   
72.
Retinoids (vitamin A) are known to be involved in many key biological functions in mammals, such as embryonic development, reproduction or vision. Besides standard vitamin A forms, freshwater fish tissues contain high levels of didehydroretinoids or vitamin A2 forms. However, the tissue distribution, metabolism and function of both standard and particularly the didehydroretinoids are still poorly known in fish. In this study, we have quantified the levels of retinoids, including retinol, retinaldehyde, retinyl palmitate and their corresponding didehydro forms, as well as the levels of the active polar retinoids all-trans-, 9-cis- and 13-cis-retinoic acid in distinct tissues of juvenile rainbow trout. Our results indicate that the liver is clearly the main retinoid storage tissue in juvenile rainbow trout. Didehydroretinoids were dominant over retinoids in all analyzed tissues with the exception of plasma. Additionally, significant differences among tissues were observed between retinoids and didehydroretinoids, such as differences in the ester profiles and the proportions between free and esterified forms, suggesting that mechanisms that favor the utilization or storage of one of the other groups of compounds might exist in fish. Our data also show the presence of polar retinoids in different tissues of fish at the fmol/g scale. Overall, this study clearly demonstrates the presence of tissue-specific patterns of accumulation of both polar and nonpolar retinoids in fish tissues. The biological relevance of these findings should be the focus of future studies.  相似文献   
73.
Although the haplotype data can be used to analyze the function of DNA, due to the significant efforts required in collecting the haplotype data, usually the genotype data is collected and then the population haplotype inference (PHI) problem is solved to infer haplotype data from genotype data for a population. This paper investigates the PHI problem based on the pure parsimony criterion (HIPP), which seeks the minimum number of distinct haplotypes to infer a given genotype data. We analyze the mathematical structure and properties for the HIPP problem, propose techniques to reduce the given genotype data into an equivalent one of much smaller size, and analyze the relations of genotype data using a compatible graph. Based on the mathematical properties in the compatible graph, we propose a maximal clique heuristic to obtain an upper bound, and a new polynomial-sized integer linear programming formulation to obtain a lower bound for the HIPP problem.  相似文献   
74.
75.
Na‐based batteries have long been regarded as an inexpensive, sustainable candidate for large‐scale stationary energy storage applications. Unfortunately, the market penetration of conventional Na‐NiCl2 batteries is approaching its limit for several reasons, including limited rate capability and high Ni cost. Herein, a Na‐FeCl2 battery operating at 190 °C is reported that allows a capacity output of 116 mAh g?1 at an extremely high current density of 33.3 mA cm?2 (≈0.6C). The superior rate performance is rooted in the intrinsically fast kinetics of the Fe/Fe2+ redox reaction. Furthermore, it is demonstrated that a small amount of Ni additive (10 mol%) effectively mitigates capacity fading of the Fe/NaCl cathode caused by Fe particle pulverization during long‐term cycling. The modified Fe/Ni cathode exhibits excellent cycling stability, maintaining a discharge energy density of over 295 Wh kg?1 for 200 cycles at 10 mA cm?2 (≈C/5).  相似文献   
76.

Background/aims

The aim of the present study is to probe the potential association between previously-reported GARP2 mutations and retinitis pigmentosa (RP) using Scottish RP patients and controls.

Methods

Exons 4, 5 and 8 in DNA from blood or buccal samples (130 autosomal recessive and simplex RP patients, 31 controls) were amplified and analysed for single-strand conformational polymorphism by capillary electrophoresis (CE-SSCP) and confirmed by sequencing.

Results

The p.Arg86Gln mutation in exon 4 was found in just one patient (out of 130), and in 10 of the 31 unaffected subjects. All of these occurrences were in people of West African origin (patient and controls). Two polymorphisms in exon 5, p.His100Arg and p.Gly109Gly, and a c.534+20A>G change in the intronic region flanking the 3′ end of exon 8 were also found not to be associated with RP.

Conclusions

The Scottish population examined here had no mutations in the GARP2 exons surveyed that could be associated with RP. The p.Arg86Gln mutation actually appears to be a polymorphism common in ethnic West Africans and not associated with RP. This change may provide a useful marker for West African ancestry.  相似文献   
77.
纯培养条件下不同氧化铁的微生物还原能力   总被引:28,自引:1,他引:27  
曲东  Sylvia  Schnell 《微生物学报》2001,41(6):745-749
The microbial reduction of ferrihydrite,lepidocrocite,hematite,goethite and aluminum-substituted iron oxides were examined by iron-reducer GS-15 under anaerobic pure culture condition.The results indicated that the ferrihydrite and lepidocrocite can be rapidly reduced by iron-reducer,and the percentage of microbial reduction are respectively 95.4% and 95.8% after 4 days incubation at 25℃.The other iron oxides like hematite,Al-hematite,goethite and Al-goethite are very difficult to reduce during short-term I…  相似文献   
78.
胡桃揪、落叶松纯林及其混交林根际土壤有效磷特性的研究   总被引:15,自引:2,他引:13  
用剥落分离采集胡桃揪(Juglans mandshurica)、落叶松(Larix gmelinii)纯林及其混交林根际与非根际土壤并分析有效P含量特性。结果表明,落叶松纯林根际土有效P含量较非根际土高出55.8%,而胡桃揪纯林根际土有效P含量较其纯林仅高10.1%,表现出落叶松根第泽根际P较强的活化能力。树种混交后,借助落叶松根系的作用使混交林中胡桃揪根际土有效P含量较其纯林高出45.2%,通过P的吸附/解吸及无机P分级等方面,对落叶松根际土壤有效P含量较高的原因进行了分析。  相似文献   
79.
The binary phase behavior of pure 1,3-dimyristoyl-2-stearoyl-sn-glycerol (MSM) and 1,2-dimyristoyl-3-stearoyl-sn-glycerol (MMS) was investigated in terms of polymorphism, melting and crystallization behavior, SFC, hardness and microstructure. Samples were crystallized at cooling rates of 3.0 and 0.1 degrees C/min. The asymmetric TAG demonstrated lower melting and crystallization points at both cooling rates. All samples crystallized in the beta' polymorph when cooled at 0.1 degrees C/min and in the alpha polymorph when cooled at 3.0 degrees C/min. The experimentally determined kinetic phase diagram of MSM-MMS was monotectic for both cooling rates. This data was well described by a thermodynamic model using the Bragg-Williams approximation for non-ideality of mixing and suggested that in both the solid and liquid states, like pair interactions (MSM-MSM and MMS-MMS) were favored over MSM-MMS interaction. A strong tendency to phase separation in the solid phase was also observed. For both cooling rates, the fit of the SFC (%)-time curves to a modified form of the Avrami model indicated that crystallization occurred in two distinct kinetic steps. Depressions seen in SFC did not correspond to depressions in hardness or melting temperatures.  相似文献   
80.
池玉杰  王志娟 《菌物学报》2004,23(4):568-572
描述了8种 引起木材腐朽的伞菌的培养特性,它们隶属于口蘑科和球盖菇科,在林地中多生长在腐木上(为木材腐朽的次要原因或处于木材腐朽演替的后期阶段),这8种菌是真姬菇Hypsizygus marmoreus、洁丽香菇Lentinus lepideus、粘小奥德蘑 Oudemansiella mucida、止血扇菇Panellus stypticus、铃形干脐菇Xeromphalina campanella、簇生黄韧伞Naematoloma fasciculare、滑菇 Pholiota nameko和尖鳞伞Pholiota squarrosoides。  相似文献   
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