生物能力学原理在红麻好氧性微生物脱胶中的应用

用实验证实了红麻纤维在微生物好氧条件下的脱胶速度比在厌氧条件下快四倍,且前者残胶率也低于后者.根据生物能力学原理并通过ATP数量计算从理论上论证了上述的实验结果.

线粒体缺陷与阿尔采末病

阿尔采末病（ Ａｌｚｈｅｉｍｅｒ＇ｓ ｄｉｓｅａｓｅ ，ＡＤ） 存在线粒体氧化磷酸化异常与线粒体ＤＮＡ（ ｍｔＤＮＡ） 缺陷，主要表现为：线粒体呼吸链复合体Ⅳ（ 细胞色素ｃ 氧化酶，ＣＯＸ）活性在ＡＤ 患者血小板、培养的皮肤成纤维细胞及脑中显著下降。其可能机制是遗传性ｍｔＤＮＡ 突变与自由基介导的体细胞ｍｔＤＮＡ 突变的共同作用，也可能继发于其它改变。氧化磷酸化缺陷可能与β淀粉样蛋白（βａ ｍｙｌｏｉｄ） 沉积、微管相关蛋白ｔａｕ蛋白的异常磷酸化调节有关。

呼吸代谢对植物细胞生命过程运转的某些控制方式

本文提出了呼吸代谢是生物体内寓同化于异化的基本生理功能的新概念。论证了呼吸代谢与细胞生命系统自组织的关系。探讨了呼吸代谢通过多条途径对植物异养细胞能力系统的整合与调控,光呼吸对自养细胞光合作用的反馈作用,以及在靶细胞中呼吸作用受植物激素的调节。

Mechanical properties and pore structure deformation behaviour of biomedical porous titanium

Porous titanium has been shown to exhibit desirable properties as biomedical materials. In view of the load-bearing situation, the mechanical properties and pore structure deformation behaviour of porous titanium were studied. Porous titanium with porosities varying from 36%-66% and average pore size of 230 μm was fabricated by powder sintering. Microstructural features were characterized using scanning electron microscopy. Uniaxial compression tests were used to probe the mechanical response in terms of elastic modulus and compressive strength. The mechanical properties of porous titanium were found to be close to the those of human bone, with stiffness values ranging from 1.86 to 14.7 GPa and compressive strength values of 85.16-461.94 MPa. The relationships between mechanical properties and relative densities were established, and the increase in relative density showed significant effects on mechanical properties and deformations of porous titanium. In a lower relative density, the microscopic deformation mechanism of porous titanium was yielding, bending and buckling of cell walls, while the deformation of yielding and bending of cell walls was observed in the porous titanium with higher relative density.

PROPERTIES OF BIODEGRADABLE THERMOPLASTIC STARCH

Thermoplastic starch is a kind of modified starch produced by mixing starch with additives and processing the mixture in an extruder. The mechanical properties, including tensile strength and elongation at break, biodegradability and rheological properties were studied. Glycerol and urea, to some extent, can both decrease the tensile strength and increase percentage elongation at break, because the former acts as a plasticizer and the latter can break down interactions among starch macromolecules. Thermoplastic starch shows thermoplasticity and its melt behaves as a pseudoplastic liquid at a low shear rate. Its biodegrading extent is slightly higher than that of native starch. The molecular weight of starch displays a decreasing tendency after thermoplastic modification.

Effect of heat treatment on microstructure, mechanical properties and in vitro degradation behavior of as-extruded Mg-2.7Nd-0.2Zn-0.4Zr alloy

Mg-2.7Nd-0.2Zn-0.4Zr （mass fraction, %） alloy was designed for degradable biomedical material. The ingots of the alloy were solution treated and then hot extruded. The extruded rods were heat treated with aging treatment, solution treatment and solution＋aging treatment, respectively. Microstructures of the alloy were observed by optical microscopy （OM） and scanning electron microscopy （SEM）. Mechanical properties at room temperature were tested. In vitro degradation behavior of the alloy immersed in simulated body fluid was measured by hydrogen evolution and mass loss tests. The degradation morphologies of the alloy with and without degradation products were observed by SEM. The results show that the grains grow apparently after solution treatment. Solution treatment improves the elongation of as-extruded alloy significantly and decreases the strength, while aging treatment improves the strength and reduces the elongation of the alloy. The yield ratio is reduced by heat treatment. The in vitro degradation results of the alloy show that solution treatment on the as-extruded alloy results in a little higher degradation rate and aging treatment on the alloy can reduce degradation rate slightly.

Microstructure and properties of biodegradable β-TCP reinforced Mg-Zn-Zr composites

Magnesium alloys have good biocompatibility, but their mechanical properties and corrosion resistance may not be satisfied for using as degradable materials within bone due to its high corrosion rate in the physiological environment. Nano β-TCP particles were added into Mg-Zn-Zr alloy to improve its microstructure and the properties. As-extruded Mg-3Zn-0.8Zr alloy and Mg-3Zn-0.8Zr/xβ-TCP （x=0.5%, 1.0% and 1.5%） composites were respectively fabricated. The grains of Mg-Zn-Zr/β-TCP composites were significantly refined. The results of the tensile tests indicate that the ultimate tensile strength and the elongation of composites were improved with the addition of β-TCP. The electrochemical test result in simulation body fluid shows that the corrosion resistance of the composites was strongly enhanced comparing with that of the alloy. The corrosion potential of Mg-3Zn0.8-Zr/1.0β-TCP composite is 1.547 V and its corrosion current density is 1.20×10 6 A/cm 2 .

Direct extrusion of thin Mg wires for biomedical applications

Biodegradable wires,able to provide load-bearing support for various biomedical applications,are the novel trends in current biomaterial research.A thin 99.92%Mg wire with a diameter of 250μm was prepared via direct extrusion with an extreme reduction ratio of 1:576.The total imposed strain in a single processing step was 6.36.Extrusion was carried out at elevated temperatures in the range from 230 to 310℃and with various ram speeds ranging from^0.2 to^0.5 mm/s.The resulting wires show very good mechanical properties which vary with extrusion parameters.Maximum true tensile stress at room temperature reaches^228 MPa and ductility reaches^13%.The proposed single-step direct extrusion can be an effective method for the production of Mg wires in sufficient quantities for bioapplications.The fractographic analysis revealed that failure of the wires may be closely connected with inclusions(e.g.,Mg O particles).The results are essential for determining the optimal processing conditions of hot extrusion for thin Mg wire.The smaller grain size,as the outcome of the lower extrusion temperature,is identified as the main parameter affecting the tensile properties of the wires.

Effects of cold deformation on microstructure and mechanical properties of Ti-35Nb-2Zr-0.3O alloy for biomedical applications

The Ti-35Nb-2Zr-0.3O(mass fraction,%)alloy was melted under a high-purity argon atmosphere in a high vacuumnon-consumable arc melting furnace,followed by cold deformation.The effects of cold deformation process on microstructure andmechanical properties were investigated using the OM,XRD,TEM,Vicker hardness tester and universal material testing machine.Results indicated that the alloy showed multiple plastic deformation mechanisms,including stress-inducedα'martensite(SIMα')transformation,dislocation slipping and deformation twins.With the increase of cold deformation reduction,the tensile strength andhardness increased owing to the increase of dislocation density and grain refinement,and the elastic modulus slightly increasedowing to the increase of SIMα'phase.The90%cold deformed alloy exhibited a great potential to become a new candidate forbiomedical applications since it possessed low elastic modulus(56.2GPa),high tensile strength(1260MPa)and highstrength-to-modulus ratio(22.4×10-3),which are superior than those of Ti-6Al-4V alloy.

BIOMECHANICAL STUDY ON UNILATERAL SINGLE-PLANE EXTERNAL FIXER

Six tibias removed from 30-40 years old males, who died in an accident for in less than 12 hours, were osteotomized at one-third supra-medium segment. They were fixed by an unilateral adjustable external fixer (UAEF), to be used as a model of external fixation of tibial fracture (MEFTF). The compression. tension, torsion, antero-posterior and lateral bending strength, and the strength for vertically extracting the pins from the tibia were determined in the MEFTF. Within a certain range of load, the correlation of strain to stress was basically a linear relationship. These data provide a theoretical basis of biomechanics for the improvement of UAEF and for early exercises of fracture patients, such as extend-bending of the joint.raising the limb and walking with a walking stick.

Challenges of incorporating gene expression data to predict HCC prognosis in the age of systems biology

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide.The recurrence of HCC after curative treatments is currently a major hurdle.Identification of subsets of patients with distinct prognosis provides an opportunity to tailor therapeutic approaches as well as to select the patients with specific sub-phenotypes for targeted therapy.Thus,the development of gene expression profiles to improve the prediction of HCC prognosis is important for HCC management.Although several gene signatures have been evaluated for the prediction of HCC prognosis,there is no consensus on the predictive power of these signatures.Using systematic approaches to evaluate these signatures and combine them with clinicopathologic information may provide more accurate prediction of HCC prognosis.Recently,Villanueva et al developed a composite prognostic model incorporating gene expression patterns in both tumor and adjacent tissues to predict HCC recurrence.In this commentary,we summarize the current progress in using gene signatures to predict HCC prognosis,and discuss the importance,existing issues and future research directions in this field.

The use of environmentally sustainable bio-derived solvents in solvent extraction applications——A review

Replacement of volatile organic compounds （VOCs） by greener or more environmentally sustainable solvents is becoming increasingly important due to the increasing health and environmental concerns as well as economic pressures associated with VOCs. Solvents that are derived from biomass, namely bio-derived solvents, are a type of green solvent that have attracted intensive investigations in recent years because of their advantages over con- ventional VOCs, such as low toxicity, biodegradability and renewability. This review aims to summarize the use of bio-derived solvents in solvent extraction applications, with special emphasis given to utilization of biodiesels and terpenes. Compared with the conventional VOCs, the overall performance of these bio-derived solvents is comparable in terms of extraction yields and selectivity for natural product extraction and no difference was found for metal extraction. To date most researchers have focused on laboratory scale thermodynamics studies. Future work is required to develop and test new bio-derived solvents and understand the kinetic performance as well as solvent extraction nilnt nlant studies.

Effects of TaN nanoparticles on microstructure,mechanical properties and tribological performance of PEEK coating prepared by electrophoretic deposition

In order to solve the friction,wear and lubrication problems of titanium,a series of TaN/ployether−ether−ketone(PEEK)coatings were developed by electrophoretic deposition,and the effects of TaN nanoparticles on the microstructure,mechanical properties and tribological performance of coatings were explored.Results manifest that the introduction of TaN nanoparticles into PEEK coatings could improve the deposition efficiency,enhance the resistant deform capacity,increase the hardness,elastic modulus and adhesive bonding strength.Compared with the pure PEEK coating,the friction coefficient of P-TN-3 was greatly reduced by 31.25%.The wear resistance of P-TN-3 was also improved in huge boost,and its specific wear rate was decreased from 9.42×10^(−5) to 1.62×10^(−5) mm^(3)·N^(−1)·m^(−1).The homogeneous composite TaN/PEEK coatings prepared by electrophoretic deposition were well-adhered to the titanium alloy substrate,TaN nanoparticles could improve the strength of PEEK coating,and provide wear-resistance protection for titanium alloys.

Brain-derived neurotrophic factor(BDNF) as a potential mechanism of the effects of acute exercise on cognitive performance

The literature shows that improvements in cognitive performance may be observed following an acute bout of exercise. However, evidence in support of the biological mechanisms of this effect is still limited. Findings from both rodent and human studies suggest brain-derived neu- rotrophic factor （BDNF） as a potential mechanism of the effect of acute exercise on memory. The molecular properties of BDNF allow this protein to be assessed in the periphery （pBDNF） （i.e., blood serum, blood plasma）, making measurements of acute exercise-induced changes in BDNF concentration relatively accessible. Studies exploring the acute exercise--pBDNF--cognitive performance relationship have had mixed findings, but this may be more reflective of methodological differences between studies than it is a statement about the role of BDNE For example, significant associations have been observed between acute exercise-induced changes in pBDNF concentration and cognitive performance in studies assessing memory, and non-significant associations have been found in studies assessing non-memory cognitive domains. Three suggestions are made for future research aimed at understanding the role of BDNF as a biological mechanism of this relationship： 1） Assessments of cognitive performance may benefit from a focus on various types of memory （e.g., relational, spatial, long-term）; 2） More finegrained measurements of pBDNF will allow for the assessment of concentrations of specific isoforms of the BDNF protein （i.e., immature, mature）; 3） Statistical techniques designed to test the mediating role of pBDNF in the acute exercise-cognitive performance relationship should be utilized in order to make causal inferences.

Does Aristotelian Magnanimity Exclude Women？

This article studies whether Aristotle＇s understanding of magnanimity excludes women. I examine Aristotle＇s concept of the biological, moral, and intellectual capacities of women in theory and practice. Although Aristotle＇s biology describes key differences between the sexes, it does not exclude women from magnanimity. While the ethical and political writings also note key differences between men and women, they leave the theoretical possibility of attaining magnanimity open. Practically, the lack of leadership opportunities available to actual women may hinder the development of prudence, leading to an inability to achieve complete virtue and hence magnanimity. Thus, if women are unable to be magnanimous, this is due to practical political and familial arrangements, not to innate feminine defects. This finding provides a unique argument for feminine leadership and political participation. Truly exceptional women may need to actively seek out leadership opportunities and political involvement in order to complete their virtue

Stem cell differentiation and human liver disease

Human stem cells are scalable cell populations capable of cellular differentiation.This makes them a very attractive in vitro cellular resource and in theory provides unlimited amounts of primary cells.Such an approach has the potential to improve our understanding of human biology and treating disease.In the future it may be possible to deploy novel stem cell-based approaches to treat human liver diseases.In recent years,eff icient hepatic differentiation from human stem cells has been achieved by several research groups including our own.In this review we provide an overview of the f ield and discuss the future potential and limitations of stem cell technology.

Evalnation of K－Supplying Power of Soils and Their Par－ticle Fractions by Electro－Ultrafiltration（EUF）

The results from comparative study of the EUF-K values of four different soils and of their varions particlefractions (<2μm, 2-10μm and 10 50μm) showed that the EUF-K values were related to the composition ofclay minerals and the soil particle size. The EUF-K values (0-35 min) were closely related to the amountof rapidly available K and part of non-exchangeable K of soils. Biological experiments proved that EUFtechnique was an effective method for evaluating soil K-supplying power.

Preparation and properties of biodegradable bamboo powder/polycaprolactone composites

The bamboo powder/polycaprolactone composites （BPPC） were prepared by torque-rheometer to investigate the effects of recipes and processing conditions on the theological properties of BPPC. The morphological behavior and mechanical properties of BPPC were also studied. Results showed that the optimum recipe for composite materials is composed of 70% of polycaprolactone, 30% of bamboo powder according to volume, 1.6 % of aluminate coupling agent, 1.2% of stearic acid, and 2% of paraffin to bamboo powder according to mass ratio The optimum processing condition parameters were determined as the rotational speed at 50 r-min^-1 and the temperature at 100℃ for BPPC. The BPPC （containing 30 copies bamboo powder） possessed eminent interfacial compatibility and mechanical properties of BPPC.

The relationship between steeplechase hurdle economy, mechanics, and performance

Background： Research surrounding the steeplechase is scarce, with most research focusing primarily on how biomechanical factors relate to maintaining running speed while crossing barriers. One area that has not been well explored is the relationship between biomechanical factors and hurdling economy. The purpose of this study was to investigate how pel：formance times and biomechanical variables relate to hurdling economy during the steeplechase. Methods： This was accomplished by measuring running economy of collegiate and professional steeplechasers while rmming with and without hurdles. Biomechanical measures of approach velocity, takeoff distance, clearance height, and lead knee extension while hurdling, as well as steeplechase performance times were correlated to a ratio of running economy with and without hurdles. Results： While oxygen uptake was 2.6% greater for the laps requiring five barriers, there was no correlation between steeplechase performance time and the ratio of running economy during the hurdle and non-hurdle laps. Results also indicated no correlation between the aforementioned biomechanical variables and ratio of running economy during the hurdle and non-hurdle laps. Conclusion： Increasing approach velocity did not negatively affect running economy. Increased approach velocity is a benefit for maintenance of race pace, but does not hurt economy of movement.

Genetic identification of two species of Pleuronichthys by DNA barcoding

DNA barcoding is a new method for biological taxonomy, offering the ability to identify species from fragments in any life-history stage. Pleuronichthys cornutus and P. japonicus are two morphologically similar species. Pleuronichthys japonicus has never been found previously in China. However, in this study, we identified both species using DNA barcoding （cytochrome c oxidase subunit I （COI））, the mtDNA control region and cytochrome b. The results reveal that： l） intraspecific variation in the DNA barcode is much less than interspecific variation; 2） the two morphologically similar species were placed into separate clades distinguishable by high bootstrap values; 3） COI barcodes are more powerful for identifying the two species than the other two mtDNA fragments.