A complete structural performance analysis and modelling of hydroxyapatite scaffolds with variable porosity

The use of hydroxyapatite (HA) scaffolds for bone regeneration is an alternative procedure to treat bone defects due to cancer, other diseases or traumas. Although the use of HA has been widely studied in the literature, there are still some disparities regarding its mechanical performance. This paper presents a complete analysis of the structural performance of porous HA scaffolds based on experimental tests, numerical simulations and theoretical studies. HA scaffolds with variable porosity were considered and fabricated by the water-soluble polymer method, using poly vinyl alcohol as pore former. These scaffolds were then characterised by scanning electron microscopy, stereo microscopy, X-ray diffraction, porosity analysis and mechanical tests. Different scaffold models were proposed and analysed by the finite element method to obtain numerical predictions of the mechanical properties. Also theoretical predictions based on the (Gibson LJ, Ashby MF. 1988. Cellular solids: structure and properties. Oxford: Pergamon Press) model were obtained. Finally the experimental, numerical and theoretical results were compared. From this comparison, it was observed that the proposed numerical and theoretical models can be used to predict, with adequate accuracy, the mechanical performance of HA scaffolds for different porosity values.     

The Effects of Seaweed Secondary Metabolites on Biofouling

Antifouling activity is one poorly investigated property of seaweed natural products. To determine, in the field, whether seaweeds contain chemicals able to influence the settlement of fouling organisms, crude organic extracts from Stypopodium zonale, Dictyota menstrualis (Phaeophyceae) and Laurencia obtusa (Rhodophyceae) were incorporated at natural volumetric concentrations, into hard stable gels that served as substrata for fouling in the experiments. Fouling organisms settled at a significantly higher rate on plates treated with S. zonale extracts than on control gels, while settlement was strongly inhibited on gels containing L. obtusa extracts. Fouling on gels treated with the D. menstrualis extract was not significantly different from the fouling found on control gels. The findings suggest that the broad antifouling properties of the crude extract of L. obtusa inhibit the settlement of fouling as well as hinder the development of settled fouling species, thereby reducing the richness of species. The results imply that L. obtusa possibly harbours powerful agents that can be explored for the development of antifouling technology.     

Characterising the structure of photosynthetic biofilms using fluid dynamic gauging

A new configuration of the fluid dynamic gauging technique for measuring soft layers on surfaces was used to monitor the growth of a cyanobacterium, Synechococcus sp. WH 5701, on stainless steel (SS), glass and an indium tinoxide (ITO) on a polyethylene terephthalate (PET) substratum. The biofilm thickness increased steadily over 4weeks and exhibited noticeable changes in microstructure and strength. The biofilms all exhibited a two-layer structure, with a compact layer next to the substratum and a loose layer above. Biofilms on ITO or SS exhibited cohesive failure when removed by fluid shear whereas those on glass exhibited adhesive failure. The technique is able to elucidate various aspects of biofilm behaviour, as illustrated by the action of a biocide (NaOCl) on a mature biofilm.     

等速肌力训练联合有氧运动对脑卒中患者肺功能、下肢运动功能及生活质量的影响

目的:探讨有氧运动联合等速肌力训练对脑卒中患者下肢运动功能、肺功能及生活质量的影响。方法:选取2016年8月～2019年9月期间我院收治的脑卒中患者130例,根据随机数字表法分为对照组(n=65,常规康复训练)和研究组(n=65,等速肌力训练联合有氧运动),比较两组患者肺功能、下肢运动功能及生活质量。结果:两组治疗8周后膝关节峰力矩(PT)、膝屈伸PT、膝屈伸耐力指数(ER)、Fugl-Meyer下肢运动功能量表(FMA-LE)评分均较治疗前升高,且研究组高于对照组(P0.05)。两组治疗8周后社会功能、躯体疼痛、精神健康、活力、健康状况、生理职能、生理机能、情感职能维度评分均较治疗前升高,且研究组高于对照组(P0.05)。两组治疗8周后用力肺活量(FVC)、第一秒用力呼气量(FEV1)、最大呼气流量(PEF)均较治疗前升高,且研究组高于对照组(P0.05)。结论:脑卒中患者给予等速肌力训练联合有氧运动,可有效改善其肺功能、下肢运动功能及生活质量,临床应用价值较高。     

Sulfate-Reducing Bacteria Release Barium and Radium from Naturally Occurring Radioactive Material in Oil-Field Barite

Scale and sludge deposits formed during oil production can contain elevated levels of Ra, often coprecipitated with barium sulfate (barite). The potential for sulfate-reducing bacteria to release ²²⁶Ra and Ba (a Ra analog) from oil-field barite was evaluated. The concentration of dissolved Ba increased when samples containing pipe scale, tank sludge, or oil-field brine pond sediment were incubated with sulfate-reducing bacteria Desulfovibrio sp., Str LZK1, isolated from an oil-field brine pond. However, Ba release was not stoichiometric with sulfide production in oil-field samples, and < 0.1% of the Ba was released. Potential for the release of ²²⁶Ra was demonstrated, and the ²²⁶Ra release associated with sulfate-reducing activity was predictable from the amount of Ba released. As with Ba, only a fraction of the ²²⁶Ra expected from the amount of sulfide produced was released, and most of the Ra remained associated with the solid material.     

Increasing of Soil Urease Activity by Stimulation of Indigenous Bacteria and Investigation of Their Role on Shear Strength

Abstract

Recent studies have shown that the use of biostimulation is an effective technique to eliminate the environmental side effects of traditional soil improvement methods. The use of indigenous bacteria of soil is a new method through which indigenous bacteria produce carbonate calcium by their urease activity. Stimulation of soil indigenous bacteria with the aim of calcite precipitation can considerably increase the soil shear strength. In this study, indigenous ureolytic bacteria are stimulated by adding nutrients to the soil. Subsequently urease activity of these bacteria in the presence of calcium chloride and nickel chloride causes calcium carbonate to precipitate between the sand particles. The analysis showed that the stimulated soil compared to the control soil was significantly different in terms of the soil engineering properties and the amount of precipitated calcite. Further, the treated and untreated samples were examined using direct shear test, scanning electron microscope (SEM), and energy dispersive X-ray (EDX) analysis. The results showed an increase of 30–67% in ultimate shear strength, 4–18.8% in residual shear strength, 190% in the cohesion intercept, and 16.8% in the angle of internal friction. In addition, imaging and analysis of SEM-EDX indicated the production of large amounts of calcite precipitates on surfaces of soil particles and between them.     

Structural analyses of the permease like protein SoxT: A member of the sulfur compound metabolizing sox operon

One of the oldest known gene clusters that are involved in biological oxidation processes is the sox operon. This operon is present in different microbial species. In the present study an attempt has been made to analyze the probable structural role of SoxT protein from Pseudaminobacter salicylatoxidans. This protein has been predicted to be a permease-like protein. A comparative model of the protein has been made and analyzed. The possible membrane spanning region of the protein has been detected by structural bioinformatics approach. The inducer of the sulfur oxidation process has been predicted. And thereby the plausible mechanism of the transport of the sulfur anion inside the bacterial cell has been elucidated. Since this is the first study regarding the structural aspect of the protein this study may shed light on the theory of the yet unknown molecular mechanism of the sulfur oxidation process by sox operon.     

不同脱落力下蜡梅花梗CpEXP1基因的表达与扩张蛋白活性

为了研究不同脱落力下蜡梅花梗中CpEXP1基因的表达水平以及扩张蛋白活性,采用real-timePcR技术检测不同脱落力下蜡梅花梗组织CpEXP1基因的表达水平;同时采用蛋白质体外重组法以及培养基添加法对花梗组织扩张蛋白活性进行测定。结果表明：CpEXP1基因的表达与扩张蛋白活性变化趋势相同,并在蜡梅花蕾脱落过程中具有阶段特异性。CpEXPI基因在自然脱落组的表达量显著高于其他组（P〈0．05）。此时扩张蛋白活性也最强。扩张蛋白对麻点百合愈伤组织的分化无明显影响,对增殖以及生根有明显促进作用。     

采油微生物在微驱过程中的生长、运移及分布规律

[目的]深入了解现场微生物驱油机理、效果评价标准及影响因素.[方法]结合现场微生物驱油过程产出液的跟踪监测及室内物模实验对微生物在地层中的生长繁殖、运移及分布规律进行研究.[结果]结果表明,通过从水井注入的外源微生物在油藏中能够有效生长繁殖,而且注入的营养液也能够激活内源微生物,但由于地层渗透率及营养液浓度的影响,产出液菌浓要比注入菌浓低1-2个数量级;葡萄糖的快速降解以及地层对微生物的过滤及吸附作用使大量的微生物停留在近井地带,仅有部分微生物能够从生产井采出,而且其运移速度要比营养液慢.[结论]地层渗透率和产出液中营养物浓度是影响微生物数量及分布的两个关键因素,现场微生物驱油产出液中的菌浓一般很难达到106个/mL以上,该研究结果对微生物驱油技术的发展和应用具有重要意义.     

Interindividual Differences in a Set of Biological Rhythms Documented During the High Arctic Summer (79°N) In Three Healthy Subjects

The High Arctic summer with its permanent sunlight provides a situation in which one of the natural synchronizers, the light-dark alternation, is minimal. During the summers of 1981 and 1982 three healthy right-handed geographers who were performing field studies in Svalbard as part of their own research volunteered to document, 4–6 times per 24 hr for respectively 63,141 and 147 days, a set of circadian rhythms: self-rated fatigue, oral temperature, grip strength of both hands, heart rate and times of awakening and retiring. Tests were performed before departure from France, in Svalbard (79°IN latitude) where their daily activities were often strenuous, and after returning to France. Time series were treated individually according to three methods: display of data as a function of time, cosinor analyses to quantify rhythm parameters, and spectral analyses to estimate component periods of rhythms. Circadian parameters such as period and acrophase of activity-rest, oral temperature and fatigue rhythms were not altered. On the other hand, the circadian rhythm in grip strength was altered: the period differed from 24 hr in one subject, while grip strength acrophase of the left, but not the right, hand of the other two subjects was phase shifted during the sojourn in Svalbard. A prominent circahemidian (about 12 hr) rhythm was observed in two subjects for their heart rate in Svalbard, while a prominent circadian rhythm (differing from exactly 24 hr) was observed in France associated with a small circahemidian component.