Longitudinal growth strains in five clones of Eucalyptus tereticornis Sm

We studied the variability in longitudinal growth strains and wood basic density in five-year old trees from five clones （one tree per clone） of Eucalyptus tereticornis. Mean longitudinal growth strain in clones ranged from 466 to 876 μm. There was a significant difference between clones in growth strains and wood basic density. Clone 10 exhibited maximum growth strains and basic density, whereas clone 3 and clone 7 exhibited minimum growth strains and basic density, respectively. Within a tree, the growth strain variation with tree height was high but statistically insignificant while within tree variation in basic density was very small. There was no specific trend in variation in either strain or density within a tree. There was 5% 200% difference in growth strain on opposite sides of the logs. However two strains showed a strong positive correlation. There was a moderate positive association of wood basic density and mean growth strains in logs. The variation around the periphery emphasize the need to measure strain more than one, preferably on opposite sides at the same height, on a tree to know the mean strain level for the purpose of selection of clones.

Preliminary Survey of Trunk Growth Strain in Six Eucalyptuses Grown in Southern China

The longitudinal displacement between two reference points upon stress release was measured throgh using the CIRAD-foret one-hole method on a total of 305 trees of 6 eucalyptuses, including Eucalyptus urophylla, E. pellita, E. teriticornis, E. camaldulensis, E. urophylla x E. grandis and E. urophylla × E. teriticornis. These trees were between 3 to 5 years old and are regarded as commercially important plantation species in China. Significant differences in the growth strain and diameter at breast height over bark （DBHOB） were observed between species, provenances and clones of the same age. The data clearly showed that, E. pellita, E. teriticornis and E. camaldulensis （provenance 15025） had higher growth rates but much lower growth strain at the tree surface, in comparison to other species / hybrids / clones. Whilst conclusive recommendations for species selection need to be substantiated with comprehensive studies that include other key wood properties, results of this study have shown trends pertaining to wood quality differences between the six species.

ELASTIC-PLASTIC CRACK GROWTH ON PLANE STRAIN BIMATERIAL INTERFACE

Finite element computations are carried out to simulate plane strain crack growth on a bimaterial interface under the assumption of small scale yielding.The modified Guron constitutive equation and the element vanish technique introduced by Tvergaard et al.are used to model the final formation of an open crack.It is found from the calculation that the critical fracture toughness for crack growth is much low- er in bimaterials than that in homogeneous material.The critical fracture toughness is strongly dependent on material properties of the bimaterial pair and the mixed mode of remote loads.The interface crack grows in the more compliant(lower hardening)material or in the weaker(lower yield strength)material.In Mode-Ⅰ loading,the crack grows zigzag along the interface.

Strain Growth in Containment Vessels

Strain growth is a phenomenon observed in containment vessels subjected to internal blast loading. The elastic response of the vessel may become larger in a later stage compared to its response during the initial stage. The dynamic responses of infinitely long cylindrical containment vessels subjected to uniformly-distributed internal blast loading are studied using LS-DYNA. The development of bending modes and the interaction between the breathing mode and bending modes are observed. The methodology developed for dynamic elastic buckling analysis is employed to study the strain growth phenomenon in explosion containment vessels. It is shown that the dynamic instable vibration of a containment vessel is the basic mechanism of strain growth.

Effect of pre-strain on fatigue crack growth of 2E12 aluminum alloy

The influences of pre-strain on the mechanical property and fatigue crack growth of 2E12 aluminum alloy were evaluated by SEM,TEM,mechanical property and fatigue tests. The axial fatigue tests were conducted under a constant amplitude sinusoidal wave loading at stress ratio of 0.1 in laboratory air and salt fog at room temperature. The results show that the yield stress of pre strain material is higher than that of the material without undergoing pre-strain,but pre-strain can not make the increase of the growth rate of fatigue crack. Fatigue crack growth rates of the alloy in salt fog are higher than those in air. The increased fatigue crack growth of the alloy in a given environment and more brittle striations can be observed in salt fog.

Effects of different proportions of two Bacillus sp. on the growth performance, small intestinal morphology, caecal microbiota and plasma biochemical profile of Chinese Huainan Partridge Shank chickens

A total of 900 one-d-old Chinese Huainan Partridge Shank chickens were randomly allocated into nine groups with five replicates of 20 each.Birds were fed with basal diet,basal diet supplemented with 150 mg kg^（–1） aureomycin,basal diet supplemented with different proportions of Bacillus licheniformis and Bacillus subtilis,which was 0：1.0×10~6,2.5×10~5：7.5×10~5,3.3×10~5：6.6×10~5,5.0×10~5：5.0×10~5,6.6×10~5：3.3×10~5,7.5×10~5：2.5×10~5 and 1.0×10~6：0,respectively.The duration of the experiment was 56 d.The results indicated that dietary supplementation of 6.6×10~5：3.3×10~5 of B.lichenifornis：B.subtilis improved final body weight,increased the average daily gain,and reduced feed/gain ratio（P〈0.05）.The numbers of total Lactobacillus and Bifidobacterium sp.in the caecum significantly increased,and the numbers of Escherichia coli and Salmonella sp.significantly declined compared to that of the control（P〈0.05）.Intestinal villous height and villous height to crypt depth ratio of the duodenum,jejunum,and ileum were significantly higher than that of the control,and intestinal crypt depth of the duodenum and ileum was significantly lower（P〈0.05）.The total antioxidant capacity,total superoxide dismutase,and glutathione peroxidase ability in plasma significantly improved,while the malondialdehyde concentration in plasma decreased（P〈0.05）.Compared to the control,plasma concentrations of ammonia,uric acid and urea nitrogen and the activity of xanthine oxidase were reduced（P〈0.05）.In conclusion,an inclusion of 6.6×10~5：3.3×10~5 of B.licheniformis：B.subtilis to the diet improved the growth performance,caecal microbiota,plasma biochemical profile,and significantly improved the small intestine morphology,while reducing the mortality rate.

Role of gelatinous layer in growth stress generation in tension wood

To elucidate what controls the magnitude of longitudinal growth stress in tension wood, anatomical measurements of gelatinous fibres were carried out on poplar tension wood (Populus I4551). Sections were cut from embedded blocks to avoid a border artefact described earlier. Results showed that: 1) no gelatinous fibres were observed under a growth strain level from 0.06% to 0.08%; 2) almost all of the non-conductive tissues contained gelatinous fibres above a growth strain level from 0.15% to 0.19%; 3) the amount of fibres, the amount of fibres with gelatinous layer, per unit of tissue area, and the thickness of the gelatinous layers controlled most of the magnitude of growth stress; 4) the contribution of the S2 layer in both fibre types could also play a role in the growth stress generation.

TRANSFORMATION OF RETAINED AUSTENITE IN CARBURIZED CASE DURING FATIGUE CRACK GROWTH

The morphology of the retained austenite in the carburized case of 20CrNiMo steel and its transformation during fatigue crack propagation through the case were investigated by using X-ray and TEM analysis.In the carburized case both film and block shaped retained austenite were found.Due to the crystallographic orientation relationship at the interface,the fatigue crack is inclined to pass through the block shaped retained austenite and thereby stim- ulates its strain-induced martensitie transformation.During the process of the fatigue frac- ture,most of the retained austenite structures on the crack path are transformed into the martensite,and the untranaformed parts on the fracture surface remain less than 6%.The transformation of the retained austenite,which is restrieted mainly within the plastic zone,oc- curs only during the proeess of fracture,and is independent of the magnitudes of the external stress,stress ratio and cyclic number.The volume expansion accompanying the transforma- tion creates an additional residual displacement of about 0.44μm on fracture surfaces,which is equivalent to the magnitude of the plasticity-induced residual displacement.The phase transformation induced fatigue crack closure is believed to be an important factor affecting the fatigue crack behaviors in the high carbon laver of the carburized case.

Selection of the Bacteria Being Able to Degrade Kerosene and Study on the Growth Conditions of the Bacteria

[Objective] The study aimed at selecting the predominant strains being able to degrade kerosene and studying its best growth conditions. [Method] Choosing kerosene as the only carbon source, we selected and separated the predominant strains being able to degrade kerosene from the contaminated soil near petrochemical plants, and then optimized the grow conditions of the bacteria. [Result] The best conditions for the bacteria growth were determined as follows, that is, temperature was 30 ℃, pH=7, salinity was 2.5%, and the rotational speed of the thermostatic shake was 190 r/min. Under the optimal conditions, the degradation rate of kerosene by the bacteria cultured for three days reached 42.6%. [Conclusion] The research could provide scientific references for the restoration of polluted soil by kerosene.

Void Formation and Growth for a Class of Compressible Hyper-Elastic Sphere

In this paper, the strain energy function proposed by Shang and Cheng was generalized by introducing a nonlinear term. Void formation and growth in the interior of a sphere composed of compressible hyper-elastic material, subjected to a prescribed uniform displacement, was examined. A parametric cavitated bifurcation solution for the radial deformed function was obtained. Stability of the solution of the cavitated bifurcation equation was discussed. With the appearance of a cavity, an interesting feature of the radial deformation near the deformed cavity wall is the transition from extension to compression.

Plant Growth Promoting Rhizobacteria Having 1-Aminocyclopropane-1-Carboxylic Acid Deaminase to Induce Salt Tolerance in Sunflower (<i>Helianthus annus L.</i>)

Soil salinity badly affects agriculture productivity through accumulation of salts in upper layers of soils. The harmful effects of salts in arable lands have influenced modern as well as ancient civilizations. A pot study was carried out to test the performance of two PGPR isolates (KS 8, KS 28) on sunflower (SMH-0917) under different salinity levels (8, 10 and 12 dS·m-1). These salinity levels were developed by adding calculated amount of salts (NaCl, Na2SO4, CaCl2 and MgSO4) with ratio of 3:4:2:1. The bacterial strains KS 8 and KS 28 were applied separately in two treatments while third treatment was co-inoculation (KS mix). Completely randomized experimental design (CRD) was used and data were collected at flowering stage about pre-decided plant growth parameters (plant height, shoot dry weight and root dry weight). The bacterial isolate KS 8 showed an increase of 26, 102% and 83% in plant height, shoot dry weight and root dry weight at EC 8 dS·m-1, while this improvement was 67%, 163% and 296% at EC 10 dS·m-1, however an increase of 100%, 74% and 382% was recorded over control respectively at EC 12 dS·m-1. Similarly isolate KS 28 exhibited an increase of 14%, 69% and 54% in plant height;shoot dry weight and root dry weight at EC 8 dS·m-1, whereas this improvement was 56%, 163% and 188% at EC 10 dS·m-1, while an increase of 60%, 41% and 282% was registered respectively over control at EC 12 dS·m-1. The increase due to mixture treatments was 4%, 41% and 16% in plant height, shoot dry weight and root dry weight at EC 8 dS·m-1, while an increase of 33%, 57% and 100% at EC 10 dS·m-1, whereas an improvement of 53%, 33% and 164% respectively was noted at EC 12 dS·m-1 over un-inoculated. The isolate KS 8 performed better than KS 28 and mixture treatment. These two PGPR strains could be used to mitigate the adverse impact caused by salinity stress on sunflower.

Growth of a Void in a Rubber Rectangular Plate under Uniaxial Extension

The finite deformation and stress analyses for a rectangular plate with a center void and made of rubber with the Yeoh elastic strain energy function under uniaxial extension were studied in this paper. An approximation solution was obtained from the minimum potential energy principle. The numerical results for the growth of the cavitation and stresses along the edge of the cavitation were discussed. In addition, the stress concentration phenomenon was considered.

Non-Local Analysis of Forming Limits of Ductile Material Considering Void Growth

The current study performed a finite element analysis of the strain localization behavior of a voided ductile material using a non-local plasticity formulation in which the yield strength depends on both an equivalent plastic strain measurement (hardening parameter) and Laplacian equivalent. The introduction of gradient terms to the yield function was found to play an important role in simulating the strain localization behavior of the voided ductile material. The effect of the mesh size and characteristic length on the strain localization were also investigated. An FEM simulation based on the proposed non-local plasticity revealed that the load-strain curves of the voided ductile material subjected to plane strain tension converged to one curve, regardless of the mesh size. In addition, the results using non-local plasticity also exhibited that the dependence of the deformation behavior of the material on the mesh size was much less sensitive than that with classical local plasticity and could be successfully eliminated through the introduction of a large value for the characteristic length.

新型鹅细小病毒徐州分离株(NGPV XZ-01株)对半番鸭生长发育的影响

为了探究新型鹅细小病毒徐州分离株(NGPV XZ-01株)对半番鸭生长发育的影响,试验将180只健康非免疫半番鸭随机分为3组,分别为对照组、3日龄攻毒组和7日龄攻毒组,每组60只,对照组于3日龄时皮下注射灭菌生理盐水0.2 mL,3日龄攻毒组和7日龄攻毒组分别于3日龄和7日龄时皮下注射NGPV XZ-01株病毒液(第7代,效价为5.7 lgELD_(50)/mL)0.2 mL,攻毒后观察并记录各组的生长发育情况、临床症状、发病和死亡情况,并对喙长和体重进行测定,于25日龄时全部扑杀,进行剖检、病理切片观察和X光检查。结果表明:攻毒后,3日龄攻毒组和7日龄攻毒组均生长发育迟缓或成僵鸭;24日龄时,3日龄攻毒组和7日龄攻毒组的体型明显小于对照组,3日龄攻毒组体型明显小于7日龄攻毒组。试验期间,3日龄攻毒组和7日龄攻毒组表现为精神萎靡不振、喜卧、打堆、排白色或黄白色粪便,部分患鸭出现运动障碍、瘫痪等症状;随着日龄的增长,上下喙变短及舌头外露的症状逐渐明显。其中3日龄攻毒组发病率为90.0%、死亡率为11.7%;7日龄攻毒组发病率为76.7%、死亡率为6.7%;对照组无发病和死亡情况。10~22日龄时,3日龄攻毒组和7日龄攻毒组的体重和喙长均显著低于对照组(P<0.05),3日龄攻毒组的体重和喙长均显著低于7日龄攻毒组(P<0.05)。3日龄攻毒组和7日龄攻毒组剖检可见泄殖腔膨大,肠道内容物稀薄,肝脏均出现水肿、质脆等病变;病理切片观察可见十二指肠肠绒毛顶端上皮细胞坏死,十二指肠绒毛不同程度脱落,部分肠腺坏死;部分肝细胞出现坏死,肝窦淤血,有炎性细胞浸润;其他脏器未见明显病变。对照组未见明显异常。X光检查可见3日龄攻毒组和7日龄攻毒组下喙、翅、腿等部位明显小于对照组,且胫骨长度远低于对照组。说明NGPV XZ-01株可使半番鸭的生长发育明显受阻,具有很强的致病性,且对半番鸭的影响随感染日龄的增加而减小。

一株旱稻联合固氮菌株的分离鉴定及促生作用

[目的]旱稻是一种重要的种质资源,对成熟期旱稻根系内生固氮菌进行筛选与鉴定,以获得对旱稻有较好促生作用的菌株。[方法]采用联合固氮固体培养基培养方法,从成熟期旱稻根系中分离出内生固氮菌,通过扩增固氮酶nifH基因和16S rRNA基因进行分子鉴定和系统进化分析生化指标测定和形态学鉴定;采用透明圈法进行溶磷、产铁载体能力验证;以褐球固氮菌为阳性对照,利用ELISA测定试剂盒测定菌株分泌固氮酶活性、1-氨基环丙烷-1-羧酸(ACC)脱氨酶,采用Salkowski比色法测定生长素(IAA)含量,并研究其生长特征。将分离的固氮菌株以1%浓度(约8×10~7CFU/mL)浸泡旱稻谷种进行催芽,研究其促生效果。[结果]分离的菌株URR45为固氮菌,属于嗜温型微生物,最适生长温度为32~50℃,最适pH为6.0~6.5,不耐盐。其分泌的固氮酶含量为220.15 U/L,ACC含量为898.69 ng/mL,生长素含量为14.91 mg/L,固氮酶含量和ACC含量显著高于对照组褐球固氮菌。该菌株能够利用葡萄糖、麦芽糖等碳源,属于发酵型细菌,具有水解明胶、溶磷和产铁载体特性。该菌株经16S rRNA基因测序后通过NCBI BLAST比对,鉴定为Herbaspirillum seropedicae,隶属于Pseudomonadota门、Betaproteobacteria纲、Burkholderiale目、Oxalobacteraceae科、Herbaspirillum属,革兰氏染色呈阴性。促生试验结果表明,在主根长度、侧根长度以及测根数方面均显著高于对照组。[结论]该菌株对旱稻幼苗具有一定的促生作用,在农业上产上可作为功能性内生固氮菌开发利用。

螺蛳粉米粉表面污染霉菌的分离鉴定

螺蛳粉米粉加工储藏过程中的霉菌污染会影响米粉品质。为明确螺蛳粉米粉上霉菌的生物多样性,该研究以柳州螺蛳粉干米粉为样品,对其表面霉菌种类进行了分离鉴定及菌落形态、孢子萌发、菌丝生长等生物学特性分析。通过ITS-rDNA测序及NCBI序列比对,分离获得的32株真菌可以分为11个属,其中青霉属(Penicillium sp.)占6.3%、枝孢属(Cladosporium sp.)占40.6%、链格孢属(Alternaria sp.)占9.4%、曲霉属(Aspergillus sp.)占9.4%,篮状菌属(Talaromyces sp.)占9.4%,以上是米粉表面主要的优势真菌;系统发育树表明,分离获得的真菌同已知真菌序列相似度均达99%以上;对优势真菌孢子萌发和菌丝生长测定发现,青霉属真菌具有较快的孢子萌发率和菌丝扩展率,而曲霉属和枝孢属真菌虽然菌丝蔓延较快,但前期产孢较少。该研究首次对米粉表面霉菌种类进行分离鉴定的报道,研究结果表明,米粉上污染的霉菌种群多样性较高,存在一定的食品质量安全风险,研究结果可为米粉霉菌污染控制消除技术开发提供借鉴。

五味子根际促生菌的筛选

【目的】从五味子根际土壤中筛选具有多种促生功能的根际促生菌,并探究其对五味子幼苗的促生效果,为五味子微生物菌肥的开发提供优良菌种资源。【方法】采用平板划线分离法从五味子根际土壤中分离纯化可培养的细菌,并通过测定其固氮、解有机磷、溶无机磷、产吲哚乙酸、产铁载体和产1-氨基环丙烷-1-羧酸(ACC)脱氨酶能力,筛选具有多种促生功能的菌株。通过16S rRNA基因序列构建系统进化树鉴定菌株的种类。通过盆栽试验探究菌株对五味子幼苗的促生效果。【结果】从五味子根际土壤中分离得到85株细菌,通过测定其固氮、解有机磷、溶无机磷、产吲哚乙酸、产铁载体和产ACC脱氨酶能力,筛选出综合促生能力较强的菌株142,其固氮能力值为1.56,解有机磷能力值为2.06,溶无机磷能力值为1.47,产吲哚乙酸质量浓度为52.34 mg/L,铁载体表达量为49.65%,产ACC脱氨酶能力(A 600)为0.22,经鉴定菌株142为沙雷氏菌属居泉沙雷氏菌(Serratia fonticola)。盆栽试验结果表明,该菌株能够促进五味子幼苗的生长,施加该菌株后五味子幼苗的株高增加了198.20%,茎粗增加了53.05%,地上和地下鲜质量分别增加了92.95%和73.95%,地上和地下干质量分别增加了111.76%和98.33%,叶绿素a和b含量分别提高了42.00%和8.11%。【结论】筛选到的居泉沙雷氏菌142对五味子幼苗的生长具有明显的促进作用。

基于应变石墨烯基底的有机分子薄膜溶液外延生长研究

有机半导体器件中的载流子微观动力学行为受有机分子的吸附取向和排列结构的影响极大。因此,研究有机分子在衬底表面的堆栈行为对于促进高性能有机半导体器件的研究极为重要。石墨烯具有模板效应,可促进有机分子的有序堆栈,从而能极大地提高相应器件的性能。在π-π耦合相互作用驱使下,有机分子(通常具有平面芳香环结构)在石墨烯衬底上通常呈现“平躺”式吸附模式。如何克服有机分子在石墨烯基底上吸附取向的单一性是“石墨烯基有机器件”研究亟待解决的问题。本文提出一种利用石墨烯应变和空间微形貌协同调控有机分子吸附取向的新策略,在具有周期性纳米级弯曲结构的石墨烯上实现了具有直立分子取向的二维超薄C8-BTBT薄膜的外延生长。研究发现,石墨烯弯曲程度和应变共同决定了C8-BTBT分子的直立几何形状及其在石墨烯表面的定向生长。本研究为控制二维材料界面上的分子外延向功能异质结构方向发展提供了一种可行的途径。

酱油中降生物胺乳酸菌的筛选、鉴定及其生长特性研究

为获得在酱油发酵中具有降解生物胺能力的乳酸菌,该研究从酱油和酱醪样品中筛选具有降生物胺功能的菌株,对目标菌株进行鉴定并研究其生长曲线、耐盐、耐酸等生长特性及降解特性。结果表明,采用稀释分离法、双层显色培养法、生物胺氧化酶定性检测和液相色谱-串联质谱法定量分析筛选得到5株高效降解生物胺的菌株,经形态学、生理生化和16S rDNA分子生物学鉴定,均为发酵乳杆菌;其中,菌株L2112、L31B2和L41B对酱油中主要生物胺——酪胺、组胺、亚精胺和苯乙胺的降解率分别达到63.76%、59.09%、43.38%和35.12%,菌株L2112和L41B耐酸耐盐能力均较好,在37℃、40 g/L NaCl和300 mg/L生物胺质量浓度时菌株L2112降生物胺能力最佳,在37℃、130 g/L NaCl和500 mg/L生物胺质量浓度时菌株L41B降生物胺能力最佳。该研究有望为酱油发酵体系中生物胺调控提供优良菌株。

促生菌黄浆水培养基优化及发酵菌液对种子萌发的影响

黄浆水含有大量的营养物质,对其资源再利用具有重要意义。通过水解圈的定性分析及氨氮含量的定量测定以筛选具氨化及溶磷作用的促生菌菌株,通过单因素、正交试验对2个菌株的黄浆水发酵培养基进行优化,利用2个菌株的发酵菌液对黑麦草及苜蓿种子进行浸种以分析其对种子萌发的影响。结果表明:恶臭假单胞菌(Pseudomonas putida)HGD3和吡咯伯克霍尔德氏菌(Burkholderia pyrrocinia) P10具有较强的氨化能力和溶磷性。在含40%黄浆水的优化发酵培养基中培养48 h, HGD3和P10菌株发酵液的氨氮浓度分别为894.92 mg/L和546.49 mg/L,较优化前分别提高6.79和2.60倍。HGD3和P10菌株发酵液的浸种均显著地提高了黑麦草和苜蓿种子的发芽率,苜蓿种子的发芽率较对照分别提高了34.51%和24.36%;黑麦草种子的发芽率分别提高了32.66%和18.85%,且萌发黑麦草的芽长分别增长1.57倍和0.77倍、根长分别增长了1.53倍和0.91倍。恶臭假单胞菌HGD3的黄浆水发酵液可以显著地促进黑麦草和苜蓿种子的萌发,尤以黑麦草为甚,研究结果为黄浆水的再利用及促生菌菌株对种子的促萌发提供了一定的理论基础。