Growth of Syntrophomonas wolfei in pure culture on crotonate

A Synthrophomonas wolfei-Methanospirillum hungatei coculture was adapted to catabolize crotonate. S. wolfei was then isolated in axenic culture using agar spread plates and roll tubes with crotonate as the sole energy source. S. wolfei catabolized crotonate via a disproportionation mechanism similar to that of some Clostridium species. Growth on crotonate was very slow (specific growth rate of 0.029 h^–1) but the conversion of energy into cell material was very efficient with cell yields of 14.6 g (dry wt.) per mol of crotonate. S. wolfei alone did not catabolize butyrate, but butyrate was stoichiometrically degraded to acetate and presumably methane when S. wolfei was reassociated with M. hungatei. S. wolfei-M. hungatei cocultures accumulated some butyrate during growth on crotonate indicating that protons were not the sole electron acceptors used for crotonate oxidation by the coculture.     

Anodic alumina films formed in sulfamic acid solution

The formation of anodic oxide films on aluminium in 5% aqueous solution of sulfamic acid is investigated. The investigations were carried out in galvanostatic conditions and at different temperatures and durations. The porosity of porous alumina samples grown under different conditions is determined by the pore-filling method and scanning electron microscopy. The effect of the current density, temperature and duration of the anodic oxidation on the morphology of the porous Al₂O₃-films is studied.     

Sodium Plating from Na‐β″‐Alumina Ceramics at Room Temperature,Paving the Way for Fast‐Charging All‐Solid‐State Batteries

All‐solid‐state batteries with an alkali metal anode have the potential to achieve high energy density. However, the onset of dendrite formation limits the maximum plating current density across the solid electrolyte and prevents fast charging. It is shown that the maximum plating current density is related to the interfacial resistance between the solid electrolyte and the metal anode. Due to their high ionic conductivity, low electronic conductivity, and stability against sodium metal, Na‐β″‐alumina ceramics are excellent candidates as electrolytes for room‐temperature all‐solid‐state batteries. Here, it is demonstrated that a heat treatment of Na‐β″‐alumina ceramics in argon atmosphere enables an interfacial resistance <10 Ω cm² and current densities up to 12 mA cm^?2 at room temperature. The current density obtained for Na‐β″‐alumina is ten times higher than that measured on a garnet‐type Li₇La₃Zr₂O₁₂ electrolyte under equivalent conditions. X‐ray photoelectron spectroscopy shows that eliminating hydroxyl groups and carbon contaminations at the interface between Na‐β″‐alumina and sodium metal is key to reach such values. By comparing the temperature‐dependent stripping/plating behavior of Na‐β″‐alumina and Li₇La₃Zr₂O₁₂, the role of the alkali metal in governing interface kinetics is discussed. This study provides new insights into dendrite formation and paves the way for fast‐charging all‐solid‐state batteries.     

Kinetic study and oxygen transfer efficiency evaluation using respirometric methods in a submerged membrane bioreactor using pure oxygen to supply the aerobic conditions

The performance of a wastewater bench-scale ultrafiltration membrane bioreactor (MBR) treatment plant using pure oxygen to supply the aerobic conditions for 95 days was studied. The results showed the capacity of the MBR systems to remove organic material under a hydraulic retention time of 12 h and a sludge retention time of 39.91 days. Aeration represents its major power input; this is why the alpha-factor of the aeration and kinetic parameters (design parameters) were determined when the mixed liquid suspended solids (MLSS) was increased from 3420 to 12,600 mg/l in order to understand the system. An alpha-factor in the range 0.462-0.022 and the kinetic parameters measured with the respirometric method (K_M of 73.954-3.647 mg/l, k_d of 0.0142-0.104 day⁻¹, k_H of 0.1266-0.655 day⁻¹, and the yield mean coefficient of 0.941) were obtained. Our study suggested significant changes in the behaviour of the biological system when the concentration of MLSS was increased.     

A Bone-remodelling Scheme Based on Principal Strains Applied to a Tooth During Translation

This paper investigates the role of principal strains within the periodontal ligament (PDL) during bone remodelling in orthodontics and particularly in the case of bodily motion (pure translation). Using analytical formulas of stress and strains within the PDL for the particular case of a paraboloidal central incisor during translation, the strains are directly related to the motion of the interface between the alveolar bone and the PDL, called bone surface. It is shown that both normal and shear strains within the PDL are of the same importance for bone surface motion. Moreover, both “mean average” and “geometrical average” of principal strains within the PDL play a significant role in the bone remodelling process, as they contribute with the same proportionality. In summary, the proposed formulas differ than previous ones that had been successfully applied to describe remodelling within long bones. The proposed theory is also sustained by a linear finite element analysis.     

Temperature effects on hyphal growth of wood-decay basidiomycetes isolated from Pinus densiflora deadwood

Hyphal growth rates were tested on malt extract agar plates at eight different temperatures (5–40?°C) using 36 isolates of 17 basidiomycete species obtained from Pinus densiflora deadwood in Japan. All isolates of four brown rot species showed optimum growth at 30?°C, whereas the optimum growth temperature of white rot species varied from 20?°C to 30?°C. Analysis using a dataset from four cooler sites showed that brown rot fungi grew more rapidly than white rot fungi at higher temperatures (25?°C, 30?°C, and 35?°C). These results suggest that the hyphal growth of brown rot fungi might be physiologically adapted to higher temperatures than those of white rot fungi among the fungal species inhabiting deadwood of P. densiflora in Japan.     

三种树脂粘接剂对纯氧化铝粘接强度的影响

目的:测定试件经过喷砂、硅溶胶热处理及与硅烷偶联剂结合的表面处理后,三种树脂粘接剂与纯氧化铝贴面的剪切强度。方法:选取高纯度的α-Al_2O_3纯氧化铝试件30个,将其随机分为A(可乐丽菲露SACTM复合树脂粘接剂)、B(Vorilink N树脂粘接剂)、C(RelyXTM Unicem树脂粘接剂)三组,每组10个。与试件粘接,在恒温水浴37℃的环境下静置24 h后测试其剪切粘接强度。扫描电子显微镜下观察各试件粘接界面的破坏形式。结果:Vorilink N粘接强度为(18.37±2.11)、RelyXTM Unicem粘接强度为(9.98±1.22),SACTM树脂粘接材料粘接强度最好,为(25.91±2.97),显著高于Vorilink N树脂粘接剂和RelyXTM Unicem树脂粘接剂,差异具有统计学意义(P0.05)。A组全部为混合破坏,B组出现了粘接剂的内部破坏,C组既有混合破坏也有界面破坏和粘接剂的内部破坏。扫描电镜图显示A、B两组的粘接断面上有很多树脂残留,C组表面相对光滑树脂残留很少。结论:不同树脂粘接剂对纯氧化铝试件的粘接强度有影响,SACTM粘接剂的粘接效果最好。     

单频刺激声稳态诱发反应的可靠性研究

目的:通过测试正常听力青年男女的听觉多频稳态诱发反应ASSR和单频刺激声稳态诱发反应探求单频刺激声稳态诱发反应的可靠性。方法:选取32名64耳听力正常的青年人作为受试者,对其进行纯音听阈、ASSR及四个0.5、1、2、4k Hz单频刺激声稳态诱发反应阈值测试,并记录0.5、1、2和4k Hz四个频率纯音阈值及ASSR及四个单频刺激声稳态诱发反应阈值。结果:ASSR在0.5、1、2和4k Hz四个频率的反应阈值与纯音听阈阈值相关性系数分别为0.64、0.81、0.79、0.85;0.5k Hz单频刺激声稳态诱发反应阈值与ASSR阈值具有明显统计学差异,其余3个单频刺激声稳态诱发反应阈值与ASSR阈值没有统计学差异,0.5k Hz单频刺激声稳态诱发反应阈值与纯音听阈阈值相关性系数为0.81。结论:ASSR阈值与纯音听阈具有较好的相关性,0.5k Hz单频刺激声稳态诱发反应可以提高0.5k Hz ASSR阈值与纯音听阈的相关性。     

不同方法处理的纯氧化铝瓷贴面粘接强度的研究

目的:观察喷砂、酸蚀、二氧化硅水溶胶热处理等表面处理方法对纯氧化铝陶瓷贴面与树脂之间粘接强度的影响。方法:选择高纯α-Al2O3烧结的纯氧化铝陶瓷贴面样本30个,将其随机分为A、B、C三组,每组10个。分别应用不同的表面处理方法与同一种树脂进行粘结,A组采用单纯喷砂,B组采用喷砂+二氧化硅表面处理+HF,C组采用喷砂+二氧化硅表面处理+硅烷偶联剂,检测和比较各组的粘接强度。结果:C组的粘接强度最大,为23.84±0.74,明显高于A组和B组(P<0.05),而A组和B组的粘接强度比较差异无统计学意义(P>0.05)。结论:单纯喷砂或二氧化硅水溶胶热处理与HF的联合使用对纯氧化铝陶瓷贴面与树脂之间的粘接强度无明显改善,而采用喷砂以及二氧化硅水溶胶热处理与硅烷偶联剂的联合应用可取得纯氧化铝陶瓷贴面与树脂间的最大粘接效果。     

Ability of native ectomycorrhizal fungi from northern Spain to colonize Douglas-fir and other introduced conifers

 Thirty-six isolates from 27 species of native ectomycorrhizal fungi collected in northern Spain were tested for ectomycorrhiza formation with Pseudotsuga menziesii seedlings in pure culture syntheses. Thirteen of those species were also tested for ectomycorrhiza formation with six other species of conifers (two native and four introduced) to compare their colonization potential. Twenty-three fungal isolates from 18 species formed ectomycorrhizas with Pseudotsuga menziesii. The colonization level of the root system varied markedly among the different fungal species. Eight fungi colonized over 50% of the short roots. Nine fungi did not form ectomycorrhizas even though some of them were collected in pure stands of Pseudotsuga menziesii. Laccaria laccata, Lyophyllum decastes, Pisolithus tinctorius, and Scleroderma citrinum formed abundant ectomycorrhizas on all the conifers tested. Lactarius deliciosus, Rhizopogon spp., and Suillus luteus showed the greatest host specificity. The success in the introduction of some exotic conifers for reforestation in northern Spain is discussed in relation to their compatibility with native ectomycorrhizal fungi. Accepted: 28 August 1995