Construction of Oriented Structure in Inner Surface of Small-Diameter Artificial Blood Vessels:A Review

There is an urgent need for small-diameter artificial blood vessels in clinic.Physical,chemical and biological factors should be integrated to avoid thrombosis and intimal hyperplasia after implantation and to promote successful fabrication of small-diameter artificial blood vessels.From a physical perspective,the internal oriented structures of natural blood vessels plays an important role in guiding the directional growth of cells,improving the blood flow environment,and promoting the regeneration of vascular tissue.In this review,the effects of the oriented structures on cells,including endothelial cells(ECs),smooth muscle cells(SMCs)and stem cells,as well as the effect of the oriented structures on hemodynamics and vascular tissue remodeling and regeneration are introduced.Various forms of oriented structures(fibers,grooves,channels,etc.)and their construction methods are also reviewed.Conclusions and future perspectives are given.It is expected to give some references to relevant researches.

Bioprinting of Small-Diameter Blood Vessels

There has been an increasing demand for bioengineered blood vessels for utilization in both regenerative medicine and drug screening.However,the availability of a true bioengineered vascular graft remains limited.Three-dimensional(3D)bioprinting presents a potential approach for fabricating blood vessels or vascularized tissue constructs of various architectures and sizes for transplantation and regeneration.In this review,we summarize the basic biology of different blood vessels,as well as 3D bioprinting approaches and bioink designs that have been applied to fabricate vascular and vascularized tissue constructs,with a focus on small-diameter blood vessels.

Effect of heating methods on drying quality of small-diameter birch lumbers

Following a normal low temperature drying schedule, the small-diameter Birch lumbers （ 1 000mm× 45mm ×30mm） were dried with consecution-heats or intermittent-heating, visual drying defects （bow, crook, twist, check along grain and end check） were measured, and then statistical analyses were performed. It was found that the drying quality of small-diameter Birch lumbers could be improved with intermittent-heating, but the intermittent time should be prolonged. Prolonging intermittent time helped to weaken or even avoid wood distortion and drying checks. It wash＇ t helpful in avoiding crook. The drying quality of small-diameter Birch lumbers with all kinds of drying methods reached the second class of the Chinese National Standard. The drying quality reached the first class of the Chinese National Standard with the intermittent-heating in the area of visual wood defects.

SMALL-DIAMETER KOREAN PINES AND THEIR ROLES INNATURAL KOREAN PINE FOREST

Korean pine population strueture in natural Korean pine forest was studied through massive field investigation and indoor analvsis. Small-diameter Korean pines origination, growth charaeter and their roles in stand were discussed from the view of population origination and tree growth. The results show that small-diameter Korean pines origination and growth havc close relations to the overstory canopy structure dynamics and play an important role in the maintenance and development of Korean pine forest. The process from small-diameter trees to dominant canopy is a selfmaintenance phase, with diffieulty, in Korean pine population. To complete this phase, it not only demands some morphological characters and physiological conditions, but severe forest strueture conditions as well. The time for complating this phase needs separation from overstory Korean pines and converge with overstory broad-leaf trees. In vertical space, it needs to fell overstory canopy or reduce the layers of overstory canopy, and in horizontal space it should be separated from Korean pines but accompanied by broad-leaf trees.

配比施肥对柚木早期生长及叶片养分含量的影响

【目的】探究不同肥料配比对柚木幼树生长及叶片养分和叶绿素含量的影响,为确定适宜的柚木施肥方案提供参考。【方法】以柚木幼林为研究对象,采用随机区组试验设计,设置5种配比施肥处理(0.25 kg/株氮磷钾复合肥+0.25 kg/株钙镁磷肥(T1)、0.25 kg/株钙镁磷肥+2.50 kg/株有机肥(T2)、0.25 kg/株氮磷钾复合肥+0.25 kg/株氧化镁+10.00 g/株硼肥(T3)、0.25 kg/株氮磷钾复合肥(T4)、0.25 kg/株氮磷钾复合肥+1.50 kg/株钙镁磷肥(T5)),以不施肥处理为对照(CK),分析不同施肥处理柚木幼树生长量及叶片养分和叶绿素含量的变化,运用隶属函数法对不同处理的施肥效应进行综合评价。【结果】①与CK相比,不同配比施肥处理均可以提高柚木的树高、胸径和材积平均增量,其中均以T5处理柚木的树高、胸径和材积平均增量最高,较CK分别提高了44.81%,82.02%和108.72%。②与CK相比,不同配比施肥处理柚木叶片全N、全K、交换性Ca含量均无显著变化,但叶片全P、交换性Mg含量显著提升,叶片N/P值显著降低。③与CK相比,不同配比施肥处理均可以提高柚木叶片的叶绿素a、叶绿素b和总叶绿素含量,降低叶绿素a/b值,其中T5处理叶片叶绿素a和总叶绿素含量与CK差异达显著水平。④隶属函数法评价结果显示,5种配比施肥处理的肥料效应由大到小排序为T5>T3>T2>T1>T4。【结论】5种配比施肥处理均可促进柚木叶片对钙、镁、磷营养元素的吸收与累积,加快叶绿素的合成,促进柚木幼树生长量的增加,其中0.25 kg/株氮磷钾复合肥+1.5 kg/株钙镁磷肥为最佳肥料组合。

琼西南5年生柚木无性系生长性状遗传变异分析

【目的】研究柚木无性系生长性状遗传变异和年度相关性,早期选育速生优良无性系。【方法】采用6株单行小区、6次重复的完全随机区组设计,对海南省乐东县15个柚木无性系大田测定林造林后1~5 a的保存率和生长指标进行方差分析、邓肯多重比较、遗传参数估算和相关性分析,并通过主成分分析,计算综合得分,在此基础上选出速生优良无性系。【结果】造林后5 a,柚木无性系间保存率差异显著(P<0.05),无性系保存率为61.50%~83.33%,平均保存率为73.26%,无性系7509的保存率最高,为83.33%;造林后5 a,柚木无性系间树高、胸径和单株材积均呈极显著差异(P<0.001),其平均值分别为5.29 m、7.29 cm和16.34 dm^(3),以无性系74_12最高,其树高、胸径和单株材积的平均值分别为6.12 m、9.11 cm和27.45 dm^(3);造林后1~5 a柚木无性系的树高、胸径和单株材积的变异系数分别为15.02%~19.35%、13.65%~20.14%和31.04%~41.01%,重复力分别为0.697~0.858、0.819~0.847、0.751~0.854;柚木无性系生长性状的年度相关性呈显著水平(P<0.05)。【结论】柚木无性系生长性状间存在稳定的遗传变异,有较高的遗传改良潜力;为琼西南地区筛选出柚木速生无性系74_12、7114和7509,入选无性系的树高、胸径、单株材积和保存率的平均值分别为35.77 m、8.07 cm、21.27 dm和74.61%,分别比对照提高了19.21%、23.60%、75.60%和3.40%。选择后树高、胸径和单株材积的现实增益为9.07%、10.69%和30.20%,遗传增益为7.71%、9.09%和25.67%,入选的3个无性系可作为后续柚木育种和推广的优良材料。

柚木种源/家系种子表型变异及其与环境因子的相关性

通过研究柚木(Tectona grandis L.F.)不同种源、家系种子的表型性状,揭示柚木种子遗传变异规律及其对环境因子变化的响应机制,促进柚木种质资源保护和遗传改良。以广东、广西、海南和云南4个省(区)13个种源81个柚木家系种子为材料,测定种子长度、宽度、长宽比、长宽积和百粒重5个性状。结果显示:(1)柚木种子的5个表型性状在种源及家系间均存在极显著差异(P<0.01),不同家系各性状变异系数为10.27%~23.88%,不同种源各性状变异系数为4.21%~20.32%。(2)各表型性状间呈极显著相关关系,不同环境因子对种子性状的影响程度不同,经纬度、海拔、年降水量是影响柚木种子性状的主要因子,其次是年均温,年均相对湿度的影响相对较小。不同的种子性状对环境因子变化的响应也不相同,种长、种宽和长宽积对年降水量的响应最为敏感,而长宽比和百粒重则对纬度的响应最为敏感。(3)聚类分析将13个种源分为3类。柚木种子在种源和家系间均存在丰富的表型变异,种子性状受母本遗传和地理气候因子等多因素影响。研究结果为柚木多样性种质资源保护和利用提供理论基础和科学依据。

3D printed grafts with gradient structures for organized vascular regeneration

Synthetic vascular grafts suitable for small-diameter arteries(<6 mm) are in great need.However,there are still no commercially available small-diameter vascular grafts(SDVGs) in clinical practice due to thrombosis and stenosis after in vivo implantation.When designing SDVGs,many studies emphasized reendothelization but ignored the importance of reconstruction of the smooth muscle layer(SML).To facilitate rapid SML regeneration,a high-resolution 3D printing method was used to create a novel bilayer SDVG with structures and mechanical properties mimicking natural arteries.Bioinspired by the collagen alignment of SML,the inner layer of the grafts had larger pore sizes and high porosity to accelerate the infiltration of cells and their circumferential alignment,which could facilitate SML reconstruction for compliance restoration and spontaneous endothelialization.The outer layer was designed to induce fibroblast recruitment by low porosity and minor pore size and provide SDVG with sufficient mechanical strength.One month after implantation,the arteries regenerated by 3D-printed grafts exhibited better pulsatility than electrospun grafts,with a compliance(8.9%) approaching that of natural arteries(11.36%) and significantly higher than that of electrospun ones(1.9%).The 3D-printed vascular demonstrated a three-layer structure more closely resembling natural arteries while electrospun grafts showed incomplete endothelium and immature SML.Our study shows the importance of SML reconstruction during vascular graft regeneration and provides an effective strategy to reconstruct blood vessels through 3D-printed structures rapidly.

Heartwood, sapwood and bark content of teak trees grown in Karnataka, India

We evaluated heartwood, sapwood and bark content in teak trees. A total of 27 sample plots were laid out in teak plantations raised by State Forest Department in Kamataka covering different age groups （11-36 years）, density （516-2061 trees/ha） and sites. From these planta- tions, a total of 130 trees were felled for estimating the yield and bark content in relation to diameter at breast height （DBH）, age and density. Bark content ranged from 22.2%-54.3%. Heartwood and sapwood con- tent were analyzed by sampling five trees each from two different planta- tions, one 30 years old at 553 trees.ha-1 and the other 32 years old at 911 trees.ha-1. The highest heartwood proportion of stem wood volume （over-bark） was 56.3% and the lowest was 37.1%.

Growth and mineral nutrient analysis of teak (Tectona grandis) grown on acidic soils in south China

Teak （Tectona grandis L.f.） is widely planted in the world due to its high market demand, economic, ecological and social value. Its plantations have mostly been established and expanded into sites that are acidic to severely acidic in southern China. But, there are no available and specific evidence-based nutrient management techniques. To better recognize and understand the relationship between teak tree growth and nutrient content in the foliage and soil and establish nutrient norms are critical to optimally manage these young plantations. We studied the foliar nutrient and soil chemistry in 19 representative teak plantations aged 5-8 years. Regression analysis indicated that the mean annual increment of teak volume was linearly and positively correlated with foliar N, Ca, Fe and B concentrations, with soil base saturation percentage, available P and Zn concentrations, and negatively correlated with soil Al concentration. Only if the Ca and Mg contents in soil were enhanced, could the increase in soil base saturation percentage benefit teak growth. A revised classification of low-and high-yielding stands was established by using a sorting method of principal components over 6 foliar macro and 8 micro elements in a Diagnosis and Recommendation Integrated System （DRIS）. Specific DRIS norms for teak plantations in acid soils were derived. The nutrient balance of N, P, K Ca, Mg, Zn, B with Fe or A1, Ca with Mg, and Fe with AI provided a key to promote the growth of teak in acid soils. Meanwhile, soil Zn was also found as a primary trace element that affected teak growth in this study.

Genetic and morphological variation in natural teak(Tectona grandis) populations of the Western Ghats in Southern India

Teak （Tectona grandis L.f.） is a popular hardwood species native to South and South-East Asia. The possible association of ampli- fied fragment length polymorphism （AFLP） marker with morphological variables of eleven important characters viz. girth at breast height （GBH）, height of tree, bole height, branch knots, presence of fluting, spiral stem, leaf hair, leaf length/breadth ratio, branching pattern, bark colour and petiole shape for nine natural populations comprising 180 genotypes of teak （9 populations x 20 trees）. The phenogram constructed using Euclidean distances for the eleven morphological characters showed that the populations were not grouped according to their geographical origin. The Mantel＇s test for pairwise correlation between Euclidean distances of different morphological variables and genetic distances from AFLP data revealed that only petiole character （r =0.269; p =0.046） and height of tree （r =0,200; p =0.001） were significantly correlated with that of AFLP data matrix. The nine populations in this study covered a geographic area of about 1000 km stretch along the Western Ghat of South India. A test of correlation between genetic and geographic distance matrices revealed a significant positive correlation （r =0.475; p =0.009）. The lack of perfect congruence between morphological and molecular data except for geo-graphic distance, tree height and petiole character suggested that the morphological system might be useful for the morphotypes management but not appropriate to study the genetic structure of the teak populations.

Effect of auxins on axillary and de novo shoot regeneration from in vitro shoot cultures derived from forced epicormic buds of teak (Tectona grandis L.)

Akram MUHAMMAD, Aftab FAHEEM＊Abstract In this presentation, we report on de novo and axillary shoot regeneration and rooting of shoots maintained over a long term, from cultures of Tectona grandis L. Shoot-tips of teak shoots forced from epicormic buds were used as the starting material for axenie shoot-culture establishment. Long term maintenance of such axenic shoot cultures was carried out by regular sub-culturing on MS media supplemented with N6-benzyleadenine （BA, 8.8 μmol·L^-1） and indole-3-butyric acid （IBA, 2 μmol·L ^1） for 24 months. Vigorously growing shoot tips （2-3 cm long） were inoculated on the MS basal medium supplemented with different concentrations （0, 1, 2, 4, 6, 8 or 10 p.mol-L-~） of either [BA or a-naphthaleneacetic acid （NAA） for rooting. Axillary and de novo shoots were de- veloped from axillary and cut basal ends of shoots, respectively. Shoots growing on auxins were further sub-cultured （every 15 days） and maintained for 45 days. The greatest number of de novo （5.06） as well as axillary shoots （2.85） was observed on the MS medium supplemented with 10 μmol-L^-1 NAA or 8 μmol·L^-1 IBA, respectively, after 45 days. The combinations of both IBA （μmol·L^-1） ＋ NAA （μmol·L^-1） were tested at different concentrations （4 ＋ 4, 6 ＋ 6, 8 ＋ 8） supplemented to a half strength MS basal medium with 0.1% activated charcoal for rooting of decapitated and non-decapitated de novo and axillary shoots. Rooting from non-decapitated de novo shoots was highest （93.33%） with a mean number of roots of 4.61 on this medium, supplemented with 6 μmol·L^-1 IBA ＋ 6 gmol.L l NAA, after 36 days of initial culture. Individual auxin, however, was not effective for root induction. Rooted shoots were acclimatized in a green house and after four weeks plantlets were transferred to the field.

Genetic transformation of cry1A(b) gene into teak

Teak (Tectona grandis) provides one of the most highly sought after timber in the world and is a widely recommended species for reforestation. As such teak is widely planted in Malaysia. Though no serious outbreaks have been recorded for teak in Malaysia, but insect attack remains the most important threat to the timber industry. Thus, in efforts to overcome the problem, an integrated pest management system needs to be developed. Spraying of commercial Bt has been a common practice in addressing minor outbreaks. However, one of the main limitations of the spraying technique is poor coverage, especially on plant surfaces. Poor coverage, however, could be overcome by planting insect resistant trees. In addition, the approach of using genetic engineering in addressing the above problem proves to be possible with the advancement made in genetic transformation of trees especially in the last decade. This, together with improved knowledge on gene function following improved DNA recombinant techniques promises the major advancement in pest management of forest species. This report demonstrates the possibility of transferring foreign gene into teak cells. In this study, nodal segments of teak were subjected to particle bombardment. Nodal segments bombarded with gold particles coated with plasmid DNA carrying hygromycin phosphotransferase (hpt), β glucuronidase (gus) and cry1A(b) genes were then transferred onto medium for shoot development. The shoots were than transferred onto the same medium supplemented with 10mg/L hygromycin for selection. Selection was repeated several times with six week subculture intervals on the same Hm containing media. The presence of the transgenes in the Hmr plants was confirmed using PCR.

Morphological parameters and genetic diversity of progenies from seed production areas and unimproved stands of teak(Tectona grandis L.f.)in India

We compared morphological and genetic attributes of prog- eny obtained from three seed production areas （SPAs） and three corre- sponding unimproved stands （UIS） of teak （Tectona grandis L.f） at three broad teak growing regions in the state of Karnataka, India. In general, seed morphological parameters such as seed weight, seed size and seed emptiness were significantly superior in SPAs compared to UISs. Seed germination percentage was also higher in seeds from SPAs. Seedling performance measured at two monthly intervals for six months was ob- served to be superior in SPAs at two of the three regions compared. Although the genetic diversity of progeny of SPAs was lower than UIS at all regions, the values were moderately high. Germination percent was positively correlated with fruit weight and kernel weight per seed, while diversity indices were negatively correlated with fruit weight, fruit di- ameter and kernel weight per seed. SPAs proved important as a source of moderately improved planting material with no severe threat to the ge- netic diversity of future plantations.

The effects of teak monoculture on forest soils: a case study in Bangladesh

Teak plantations date back to 1871 in Bangladesh. This study was designed to assess how teak monoculture has impacted the soil properties in Bangladesh. Multiple linear regression and correlation matrices were estimated to evaluate these impacts. The means of soil physicochemical properties were compared across various attributes of the plantations. Older plantations accumulated more organic carbon in the soils than the younger plantations. Excessive removal of litter from the forest floor resulted in reduced levels of N, P, K, and other nutrients in the soils. Since bulk density was continuously decreasing deeper into the soil, the penetration of mineral nutrients into the soil was low. Furthermore, moisture content in the topsoil was significantly lower than that in the bottom layers due to the exposed and dry condition of the forest floor under teak plantations. For improving depleted teak plantation soils, teak could be planted with other tree species rather than just in monocultures. In addition, the forest floor could be enriched with leguminous herbs and shrubs to improve soil health in these plantations.

11年生柚木无性系遗传变异与优良无性系选择

以从每个柚木(Tectona grandis L.f.)种源试验林、家系试验林的种源以及国内早期引种的人工林(片林)中各选出的3株以上最优单株,经组培繁殖的23个无性系为研究对象,以海南尖峰岭无性系种子园中选出1株优树采集种子培育的实生苗为对照,所有苗木以1年生营养袋苗经修剪后的裸根截干造林;以云南省普洱市景谷傣族彝族自治县益智乡的威远江干热河谷为试验地,采用完全随机区组设计,6株单行小区,6次重复;穴状整地,2010年6月9—10日种植,株行距2.5 m×4.0 m,种植后3 a抚育8次、追肥4次;11年生时,测定无性系的树高、胸径、冠幅、树干通直度,计算单株材积;采用统计分析软件(Genstat)以单株观测值为统计单元进行生长性状和形质性状方差分析、邓肯多重比较和主成分分析,采用ASReml-R软件计算表型相关性、遗传相关性等;依据各无性系主成分得分,按20%的入选率综合遴选优良无性系。结果表明:11年生6个性状柚木无性系间差异达极显著,其中,7029无性系的树高、胸径、单株材积、冠幅与对照差异显著,分别提高了9.21%、18.73%、45.36%、16.38%,分别是试验林平均值的1.22、1.32、1.93、1.34倍。不同性状表型变异系数范围为0~69.39%,单株材积变异系数最大(达34.26%~69.39%);无性系各性状主要受遗传影响,重复力较高(达0.8885~0.9419)。柚木无性系树高、胸径、单株材积、冠幅,相互间的表型相关和遗传相关达极显著正相关;无性系树干通直度,与树高、胸径、单株材积、冠幅的遗传相关显著,表型相关不显著。以各无性系在贡献率95.45%的第一主分得分值大小和20%的入选率,综合选出4个优良无性系(7029、7531、Z408、8301),树高、胸径、单株材积、树干通直度、冠幅的遗传增益,分别为12.82%、17.24%、45.58%、4.96%、17.50%;其中最优的7029无性系遗传增益极显著,分别达到20.35%、28.74%、82.53%、6.02%、31.82%。

Effects of Silvicultural Alternatives on Model-Based Financial Evaluation of Teak (<i>Tectona grandis</i>L.) Farm Forestry Management for Small-Scale Farmers in Northeast Thailand

Teak (Tectona grandis L.) plantation management is said to be profitable, but small-scale farmers with teak plantations need to find appropriate and effective choices for plantation management because of their small plots. There have been few studies on how combinations of site quality, rotation and plant spacing affect financial evaluations of teak plantation management quantitatively. In this study, we introduced the yield table for teak plantations in Northeast Thailand, and investigated the effects of site quality with rotation (15-year and 20-year) and spacing (2 m × 4 m and 4 m × 4 m) on the financial evaluation of teak plantation management using discounted cash flow analysis. The equivalent annual incomes (EAI) and benefit/cost ratios (BCR) were negative and <1, respectively, at site indexes (SI) of 14 and 18, but increased ~2 - 3 times as SI rose from 22 (site of medium quality) to 26 and 26 to 30. The 20-year rotation was generally preferable to the 15-year one, especially at SI 22. At SI 30, 2 m × 4 m was more profitable than 4 m × 4 m for both rotations, but at SI 22, 20-year rotation with 4 m × 4 m was the most profitable, followed by 20-year with 2 m × 4 m.

Erratum to “Effects of Silvicultural Alternatives on Model-Based Financial Evaluation of Teak (Tectona grandis L.) Farm Forestry Management for Small-Scale Farmers in Northeast Thailand” [Open Journal of Forestry, 4 (2014) 558-569]

The original online version of this article (Noda, I. et al. (2014). Effects of Silvicultural Alternatives on Model-Based Financial Evaluation of Teak (Tectona grandis L.) Farm Forestry Management for Small-Scale Farmers in Northeast Thailand. Open Journal of Forestry, 4, 558-569. http://dx.doi.org/10.4236/ojf.2014.45060) was published in October. The author wishes to correct Table 5.

Development of heartwood,sapwood,bark,pith and specific gravity of teak(Tectona grandis)in fast-growing plantations in Costa Rica

To elucidate the development of heartwood,bark,sapwood,pith and specific gravity of wood in fastgrowing teak(Tectona grandis)plantations in Costa Rica,we sampled three trees in each of 55 plantations and modelled each variable with age,site and different tree heights.Age and stand density of plantations were significant correlated with stem diameter at breast height and total height of the tree.Formation of heartwood was initiated at the age of 4-year-old and increased in direct proportion with age.The age of plantation had a significant relationship with stem diameter at breast height,heartwood percentage,sapwood thickness,sapwood percentage,percentage of bark,pith diameter and percentage,and specify gravity.The model for these tree parameters was model with these parameters as dependent variable and in relation to age as independent variable.

Effect of Climatic Factors on the Radial Growth of Teak （Tectona grandis L.F.） in Parakou and Tchaourou Districts in Northern Benin

Climatic factor＇s effect was studied on the radial growth of teak （Tectona grandis L.F.） by using the stem analysis of 36 trees distributed in 6 plantations in Parakou and Tchaourou districts in northern Benin. The results showed that the plantations of Parakou were in general more productive than those of Tchaourou. The annual average growth was estimated in the first five years at 0.86 cm/year for Parakou and 0.76 cm/year at Tchaourou. The analysis of the radial growth showed that a significant percentage of the variance was allotted to the growth model. It follows that a big part of the ring width was predetermined before the intervention of the other factors, in particular the climatic conditions. The percentage of the variance related to the climatic conditions was thus more reduced for the plantations of Tchaourou than those of Parakou. The radial growth was influenced by the conditions of humidity （evapotranspiration, humidity and rain） of February to May on the one hand and those from August to October on the other hand.