Extreme sexual dimorphism in a Miocene hominoid

Some Miocene hominoids may have been extremely sexually dimorphic for body size, inferred from the apparent dimorphism of dental and gnathic remains. But this has never been demonstrated convincingly for any fossil species because of small sample sizes, uncertainties about the number of species in most fossil samples, and the inability to reliably sex individual specimens. Here we demonstrate a case of extreme dental dimorphism, and presumed body-size dimorphism, in a Miocene hominoid sample in which these limitations have been overcome. Lufengpithecus lufengensis from the late Miocene site of Lufeng, China, was more dimorphic than the most dimorphic living hominoid, the orangutan, and may have been more dimorphic than any living anthropoid.     

Fossil Orangutan-like hominoid teeth from Late Pleistocene human site of Mulanshan cave in Chongzuo of Guangxi and implications on taxonomy and evolution of orangutan

Fossil records indicate orangutan-like hominoids have been widely distributed in south China during Pleistocene, although currently only surviving in the tropical forests of Kalimantan and Sumatra in Indonesia. This paper describes the recently discovered hominoid fossil teeth from human site of Mulanshan cave in Chongzuo of Guangxi, whose geological age is the Late Pleistocene, about 11000 yeas age based on associated mammal fauna and U-series dating. Compared with those of modern and subfossil orangutans from Indonesia, other fossil great apes from China, the hominoid teeth from Mulanshan cave are orangutan-like, but show somehow different from Indonesia＇s orangutans, the average sizes of cheek teeth larger and occlusal enamel wrinkles less and simpler. They are classified temporarily as the subspecies of Pongo pygmaeus weidenreichi. Concerning the variations of morphological features and dental sizes of orangutan-like teeth from southern China and neighboring northern Vietnam, different subspecies or species or genus possibly, but the key evidence is necessary to be identified.     

IF 钢铸坯厚度方向洁净度演变

采用夹杂物原貌分析、扫描电镜和能谱分析、氧氮分析等手段系统分析了 IF 钢铸坯全厚度方向的洁净度变化及夹杂物分布规律.铸坯厚度方向全氧(T. O)和 N 质量分数平均值均为17×10-6.内、外弧表层1/16内 T. O、N 均高于平均值5%~10%,存在夹杂物聚集带;内弧1/4至外弧1/4区域 T. O、N 水平低于平均值5%~10%;表层1/16至1/4区域接近平均水平.共统计夹杂物963个,夹杂物平均粒径5.7μm,<5μm 占60%, < 10μm 占90%;Al2 O3夹杂主要存在表层5 mm 内,尺寸在2~10μm;TiN- Al2 O3和 TiN 粒子主要在距离表层5 ~ 80 mm,尺寸随深度增加而增大;TiN- TiS 和 TiS 夹杂主要在距离表面80~130 mm,尺寸1~5μm.从铸坯表层到中心主要夹杂物的分布依次是 Al2 O3、Al2 O3- TiN、TiN、TiN- TiS、TiS 和 MnS.     

Statistical analyses of metric data of hominoid teeth found in Yuanmou of China

Mesial-distal and buccal-lingual dimensions of 1 266 hominoid teeth found in Yuanmou of Yunnan Province during the period of 1986 and 1988 have been measured. The statistical analyses of the metric data show that the tooth sizes of Yuanmou hominoid can be divided into big and small two types, and most tooth dimensions display obvious bimodalities in both histograms and 2 dimensional plots. The coefficients of variance (CV) reveal that the CVs of Yuanmou hominoid tooth sizes are within or close to the CV ranges ofLufengpithecus and extant great apes. The comparisons of tooth sizes and their proportions indicate that Yuanmou hominoids have close affinities with Lefeng and Kaiyuan hominoids, and have obvious differences with Gorilla, Chimpanzee and Orangutan. The authors believe that the hominoid fossils found in Yuanmou in the past 10 years represent a single species with highly sexual dimorphism in morphology and this species may have a close evolutionary relationship with the hominoids found in Kaiyuan and Lufeng.     

Juvenile hominoid cranium from the terminal Miocene of Yunnan, China

Fossil apes are known from several late Miocene localities in Yunnan Province, southwestern China, principally from Shihuiba (Lufeng) and the Yuanmou Basin, and represent three species of Lufengpithecus. They mostly comprise large samples of isolated teeth, but there are also several partial or complete adult crania from Shihuiba and a single juvenile cranium from Yuanmou. Here we describe a new, relatively complete and largely undistorted juvenile cranium from the terminal Miocene locality of Shuitangba, also in Yunnan. It is only the second ape juvenile cranium recovered from the Miocene of Eurasia and it is provisionally assigned to the species present at Shihuiba, Lufengpithecus lufengensis. Lufengpithecus has most often been linked to the extant orangutan, Pongo pygmaeus, but recent studies of the crania from Shihuiba and Yuanmou have demonstrated that this is unlikely. The new cranium reinforces the view that Lufengpithecus represents a distinct, late surviving lineage of large apes in the late Miocene of East Asia that does not appear to be closely affiliated with any extant ape lineage. It substantially increases knowledge of cranial morphology in Lufengpithecus and demonstrates that species of this genus represent a morphologically diverse radiation of apes, which is consistent with the dynamic tectonic and biotic milieu of southwestern China in the late Miocene.     

QCM对牙釉基质蛋白在牙釉质表面的吸附行为

目的:通过石英晶体微天平技术在牙釉质表面吸附牙釉基质蛋白,进而研究牙釉质表面对不同质量浓度蛋白吸附性能的影响。方法:在石英晶片上制备牙釉质膜,将其分别浸入10、20、40μg/mL质量浓度的牙釉基质蛋白溶液;通过共振频率、耗散因子、吸附量随质量浓度的变化关系,得出牙釉基质蛋白吸附的规律。结果:共振频率随质量浓度的提高而降低;吸附量随质量浓度的提高稳定的增长;结论:在20μg/mL的蛋白溶液中,牙釉质表面吸附蛋白的成膜刚性较好。石英晶体微天平技术对牙釉基质蛋白吸附机理的研究显得更直观,是研究蛋白吸附行为的有效工具。     

等离子喷涂搪瓷瓷釉涂层的耐腐蚀性能

通过添加改性剂改性瓷釉,采用等离子喷涂技术喷涂在Q235钢表面形成耐腐涂层,利用SEM等手段对其微观结构进行了分析和表征,用静态腐蚀实验和电化学腐蚀实验对涂层的耐腐蚀性能进行了研究。研究结果表明,所有涂层在碱性溶液中都基本不腐蚀;所有涂层在酸性溶液中的腐蚀程度都比基体钢板小,且改性剂为NiO的涂层的耐酸腐蚀性能稍优于改性剂为TiO_2的涂层;涂层的耐电化学腐蚀能力要优于基体钢板,且添加NiO的涂层的耐电化学腐蚀性能稍优于添加TiO_2的涂层。搪瓷瓷釉涂层在一定程度上提高了基体钢板的耐腐蚀性能。     

3种鼢鼠牙齿釉质超微结构的比较

为探讨中华鼢鼠、甘肃鼢鼠和斯氏鼢鼠的分类地位,对它们牙齿釉质的超微结构做了分析比较。结果表明3种鼢鼠的釉柱均属于釉柱分类中的第Ⅲ型,种间差异不明显;在中华鼢鼠的牙齿釉质中有许多彼此平行的纵行管道,但在甘肃鼢鼠和斯氏鼢鼠中未发现这种管道。这一发现有力地支持了甘肃鼢鼠和中华鼢鼠是两个不同种的观点。     

多波检测技术在超声厚度检测中的应用

目的确定超声反射测厚中反射波初至时间,提高反射法测量精度。方法运用多波分析技术,通过分析超声厚度检测中横波、直达纵波、反射纵波的不同传输特性,提出了斜率法判别反射波的起跳时间。结果根据斜率不同,在波场图中可以容易地得到反射曲线。结论解决了反射法测厚中反射初至时间确定难的问题,提高了测试精度。