Dependence of mechanical properties of trabecular bone on plate–rod microstructure determined by individual trabecula segmentation (ITS)

Individual trabecula segmentation (ITS) technique can decompose the trabecular bone network into individual trabecular plates and rods and is capable of quantifying the plate/rod-related microstructural characteristics of trabecular bone. This novel technique has been shown to be able to provide in-depth insights into micromechanics and failure mechanisms of human trabecular bone, as well as to distinguish the fracture status independent of area bone mineral density in clinical applications. However, the plate/rod microstructural parameters from ITS have never been correlated to experimentally determined mechanical properties of human trabecular bone. In this study, on-axis cylindrical trabecular bone samples from human proximal tibia (n=22), vertebral body (n=10), and proximal femur (n=21) were harvested, prepared, scanned using micro computed-tomography (µCT), analyzed with ITS and mechanically tested. Regression analyses showed that the plate bone volume fraction (pBV/TV) and axial bone volume fraction (aBV/TV) calculated by ITS analysis correlated the best with elastic modulus (R²=0.96–0.97) and yield strength (R²=0.95–0.96). Trabecular plate-related microstructural parameters correlated highly with elastic modulus and yield strength, while most rod-related parameters were found inversely and only moderately correlated with the mechanical properties. In addition, ITS analysis also identified that trabecular bone at human femoral neck had the highest trabecular plate-related parameters while the other sites were similar with each other in terms of plate–rod microstructure.     

Isolation,purification and characterization of pepsin soluble collagen isolated from silvertip shark (Carcharhinus albimarginatus) skeletal and head bone

Type II pepsin soluble collagens (PSC) were isolated from skeletal and head bone of silvertip shark; and examined for their biochemical and structural properties. Among the raw materials, the protein content (8.99%) was high in skeletal bone and the ash content (28%) was high in head bone. After the collagen extraction, the raw materials contained higher amount of ash content ranging from 82 to 88%. The hydroxyproline content of skeletal and skeletal PSC (30 and 113 mg/g) was higher than those head and head PSC. Both collagens were composed of two different α-chains (α₁- and α₂-chains) and were characterized as type II collagen. Amino acid analysis of skeletal and head PSC indicated imino acid contents of 156 and 175 amino acid residues per 1000 residues, respectively. Similar, Fourier transform infrared spectra of SCII and HCII were observed, which suggested that the isolation process did not affect the secondary structure and molecular order of collagen, particularly the triple–helical structure. Denaturation temperature of skeletal PSC (31 °C) was higher than that of head PSC. SEM microstructure of the collagens depicted a porous, fibrillary and multi-layered structure. These results suggested that the PSC isolated from skeletal and head bone of silvertip shark were found to be suitable biomaterial in commercial applications as alternatives to mammalian collagen.     

The morphological study on the adrenal gland of African ostrich chicks

The morphology of the adrenal gland has been studied for a number of animal species all over the world, yet the detailed data about ostrich chick has not been reported. In the present study, the morphological features of the adrenal gland in African ostrich chicks were investigated by means of gross anatomy, light and electron microscope. Differences between the left and right adrenal glands were found in shape, size and location. The interrenal tissue and chromaffin cell interdigitated irregularly. The interrenal tissue was divided into a peripheral zone (PZ) and a central inner zone (CZ), and the PZ was further distinguished into an outer area (subcapsular zone, SCZ) and an inner area (IZ). The cellular arrangement in these zones showed evident zonation that resembled the mammalian. This phenomenon had been previously described only for the pelicanus. The cytoplasm of interrenal cells in SCZ was stained lightly than in IZ and CZ, and contained several vacuoles. Additionally, unlike CZ cells, SCZ cells appeared to contain more mitochondria and less lipid droplets. Two types of chromaffin cells: epinephrine cells and norepinephrine cells could be detected. The type 1 granules possessed a central core and a variable distance between membrane and core; the type 2 granules had an eccentric core, which leant to one side of granule and sticked to the membrane, giving a lager lacouna appearance in another side of the granule.     

4种两栖爬行动物嗅器和犁鼻器的显微结构比较

用光镜观察了4种两栖爬行动物嗅器和犁鼻器的组织结构.结果显示,北方山溪鲵(Batrachuperus tibetanus)鼻囊内开始分化出犁鼻器,犁鼻器位于嗅器的腹外侧,但犁鼻器还不发达;隆肛蛙(Feirana quadranus)犁鼻器与嗅器虽然共同位于鼻囊内,但犁鼻器较为发达且其周围有发达的犁鼻腺,犁鼻器通过一细小管道与嗅器相通;秦岭蝮(Gloydius qinlingensis)和菜花烙铁头(Trimeresurus jerdonii)犁鼻腔与鼻腔已经完全分离形成两个独立的囊,而且鼻腔又进一步分化为嗅部与呼吸部.说明犁鼻器从有尾两栖动物开始出现,至无尾两栖类开始分化,到蛇类高度发达且成为一个独立器官.犁鼻器的形成是脊椎动物适应陆地生活的直接结果,是四足动物的特征之一.     

Ecological adaptation characteristics of Populus euphraticaeuphratica and Tamarix ramosissima leaf microstructures in the lower reaches of Tarim River

In order to explore the ecological adaptation in leaf microstructures of Populus euphratica and Tamarix ramosissima in the lower reaches of Tarim River; we used scanning electron microscopy to observe epidermal, cuticular and cross-sectional structures of P. euphratica and T. ramosissima leaves. In addition, their cell submicroscopic structures were studied with transmission electron microscopy. The results revealed that through long-term adaptation to the same environmental conditions, micro-structural of the leaves for the two species exhibit high degree of homoplasy: there is cavity between cuticle and epidermal, and cuticle bulges outwards to form processes mammillaris and epidermal hairs; stomata concaves; fence and vascular tissues are developed; both alisade cells and thin walled cells have chloroplast; vacuoles occupies large volume of the cell space; etc. These features help plants resist drought stress. The salt glands and salt crystallization of T. ramosissima reveals the strong ability of salt stress resistance, but its drought-resistance capacity is weaker than P. euphratica. The specific components of the various shapes of crystal structures in their leaves call for further study.     

贵州松桃寒武系清虚洞组Mongolitubulus squamifer 壳体显微结构初步研究

本文主要对贵州松桃寒武系清虚洞组灰岩中酸泡获得的管状化石Mongolitubulus squamifer壳体显微及亚显微结构进行研究。研究结果显示, M. squamifer不仅内层广泛发育纵向纤维结构,具鳞片的外层外壁也发育有微弱的纵向纤维结构,可能解释了管体外壁广泛发育的纵向开裂现象。在一枚保存有圆卵形鳞片以下部位的标本中发现,鳞片排列形式是由基部密集的小瘤点状颗粒然后过渡为不规则的圆卵形鳞片,到管体中上部逐渐形成规则排列的三角形鳞片。通过测量部分已报道的M.squamifer管体宽度与鳞片宽度发现正常发育的棘刺,鳞片大小与管体宽度有一定相关性。贵州松桃的M.squamifer壳层原始结构为2层,包括致密的具鳞片的外层和具明显纵向纤维结构的内层,管体内外层之间发育空隙导致管体容易破损。一些标本近基部断口处的层间空隙容易被次生矿物充填,导致内层增厚致密纤维结构消失或产生中间填充层。该研究揭示了M.squamifer的鳞片排列特征和壳体微观结构,为解释其亲缘关系提供新的形态学证据。     

Structural and physicochemical properties of starch gels prepared from partially modified starches using Thermus aquaticus 4-α-glucanotransferase

The modified starch gels prepared from partial enzyme treatments (1, 3, and 6 U/g starch; 2-h incubation) of the corn and rice starch pastes using Thermus aquaticus 4-α-glucanotransferase (TAαGT) were investigated for their molecular characteristics, microstructures, and physicochemical properties. Unlike the native and partially modified normal starches, the native and partially modified waxy starches could not form gels strong enough for textural analysis after 24 h for gel setting. Features of the partially modified normal starches were the specific apparent amylose contents and maximum iodine absorption wavelength (λ_max, ∼567 nm), as well as the tri-modal molecular weight profiles and flatter side-chain distributions. Also, the partially modified normal starch gels possessed fractured surfaces with discontinuous crystalline fibrous assembly that differed from the native starch gels’ porous continuous network, which resulted in more brittle, rigid, and resilient gels compared with the native gels.     

松江鲈鱼皮肤的显微和亚显微结构

采用光学显微镜、扫描电镜和透射电镜,对松江鲈鱼(Trachidermus fasciatus)成体皮肤的显微和亚显微结构进行了观察。结果表明,松江鲈鱼体表不同部位皮肤的厚薄不一,但基本结构相似。皮肤由表皮和真皮层构成。松江鲈鱼的皮肤裸露无鳞,表皮层较薄,由约4～8层细胞构成,主要由复层上皮细胞和黏液细胞及基底细胞组成。表层细胞呈扁平、多边形,细胞之间主要靠桥粒紧密连接,连接处形成增厚的边缘嵴状突起。表皮细胞游离面向内凹陷,表面形成指纹状微嵴。黏液细胞呈圆形或卵圆形,散布在上皮细胞之间。黏液细胞内的黏原颗粒具有椭圆颗粒状、均匀致密的块状和疏松丝状3种不同形态。真皮通过基膜与表皮相连,由稀疏层和致密层构成。真皮结缔组织在腹部较厚而在其他部位较薄。表皮与真皮连接处有色素层,头部、背部、尾柄和体侧皮肤色素细胞分布多,色素层明显,而腹部和颏部皮肤缺少色素。松江鲈鱼黄河群体真皮层中有角质棘状突起,而滦河群体则无。头部、体侧和尾柄处皮肤上还分布有侧线孔和表面神经丘等感觉器官。     

Influence of the Dispersed Particulate in Chocolate on Cocoa Butter Microstructure and Fat Crystal Growth during Storage

The dispersed particulates present in chocolate are shown to influence the microstructural development and fat crystal growth of cocoa butter (CB) during storage. Atomic force microscopy of both chocolate and CB showed that surface crystal growth on both materials was similar during isothermal (25 °C) storage over 4 weeks. However, unique micron-scale amorphous mounds also appeared on the surface of chocolate. With time, these regions increased in number and diameter and eventually solidified into clustered crystalline masses. X-Ray diffraction, solid fat content, and whiteness index measurements substantiated the observed crystal growth, with gradual increases in the proportion of the form VI polymorph, solid fat, and whiteness over time. Overall, these findings suggest that typical chocolate refining and tempering protocols result in a heterogeneously distributed particulate network that has a substantial impact on the morphology and crystallization pathway of the fat phase.