黎族的体成分与体质特征

1982年和1988年已经有学者报道了黎族体质人类学研究资料,近年来又报道了黎族的分子人类学研究成果。目前未见关于黎族身体组成成分的研究,也没有当前黎族的体质人类学数据。2014年11月,在海南省五指山市5个黎族村寨进行607例(男为308例,女为299例)黎族成人的人体测量。研究发现,黎族人偏瘦,肌肉较发达。随年龄增长,黎族男性体脂率的增加,主要是躯干脂肪率增大造成的,与四肢脂肪率关系不大。男性由于骨量、躯干和四肢肌肉量的下降造成瘦体质量的逐渐减小。随年龄增长,黎族女性的体脂率呈线性增大,总肌肉量呈线性减小。体脂率的逐渐增大是由于躯干和四肢的脂肪率逐渐增加造成的,总肌肉量的逐渐减小是左下肢肌肉量、躯干肌肉量逐渐下降造成的。黎族男女均为圆头型、高头型、中头型、阔面型、中鼻型、中躯干型、中胸型、宽肩型、中骨盆型、中腿型。与30年前黎族头面部资料相比,本文测量的黎族头宽、面宽值较大,头更圆些、更阔些,面更阔些,红唇较薄,形态面高值较小,男性鼻宽值较小。     

An Ion‐Exchange Promoted Phase Transition in a Li‐Excess Layered Cathode Material for High‐Performance Lithium Ion Batteries

A new approach to intentionally induce phase transition of Li‐excess layered cathode materials for high‐performance lithium ion batteries is reported. In high contrast to the limited layered‐to‐spinel phase transformation that occurred during in situ electrochemical cycles, a Li‐excess layered Li[Li_0.2Mn_0.54Ni_0.13Co_0.13]O₂ is completely converted to a Li₄Mn₅O₁₂‐type spinel product via ex situ ion‐exchanges and a post‐annealing process. Such a layered‐to‐spinel phase conversion is examined using in situ X‐ray diffraction and in situ high‐resolution transmission electron microscopy. It is found that generation of sufficient lithium ion vacancies within the Li‐excess layered oxide plays a critical role for realizing a complete phase transition. The newly formed spinel material exhibits initial discharge capacities of 313.6, 267.2, 204.0, and 126.3 mAh g^?1 when cycled at 0.1, 0.5, 1, and 5 C (1 C = 250 mA g^?1), respectively, and can retain a specific capacity of 197.5 mAh g^?1 at 1 C after 100 electrochemical cycles, demonstrating remarkably improved rate capability and cycling stability in comparison with the original Li‐excess layered cathode materials. This work sheds light on fundamental understanding of phase transitions within Li‐excess layered oxides. It also provides a novel route for tailoring electrochemical performance of Li‐excess layered cathode materials for high‐capacity lithium ion batteries.     

On the Localized Nature of the Structural Transformations of Li2MnO3 Following Electrochemical Cycling

Although the Li‐excess layered‐oxide Li₂MnO₃ has a high theoretical capacity, structural transformations within the oxide during electrochemical cycling lead to relatively low experimental capacities, hindering its use in practical applications. Here, aberration‐corrected scanning transmission electron microscopy/electron energy loss spectroscopy and high‐resolution X‐ray diffraction are used to characterize the oxide following electrochemical cycling. Microscopy reveals the coexistence of regions with local monoclinic, spinel, and rock‐salt symmetries, indicating localized and inhomogeneous structural evolutions. Crystal structure transformations are observed both at the particle surface and in the bulk. At the surface, these transformed regions resemble spinel Mn₃O₄ or rock‐salt MnO, consistent with oxygen loss. In the bulk, the regions resemble defect spinels, such as the layered‐spinel Li_xMn_4/3O₄, which suggest a partial phase transformation consistent with oxygen retention. Both microscopy and diffraction data of the cycled sample indicate areas of pristine Li₂MnO₃; the presence of such areas, in close proximity to Li_xMn_4/3O₄ areas, suggests that the layered to spinel structure transformation is partially reversible. Spinel, disordered rock salt, and pristine areas are also observed in Li₂MnO₃ samples intentionally damaged by electron beam irradiation. This observation indicates that the dynamic processes resulting in phase transformations can be studied for a variety of oxide systems by a judicious selection of irradiation conditions.     

Stabilization of Insoluble Discharge Products by Facile Aniline Modification for High Performance Li‐S Batteries

Continuous efforts have been made to attain high performance Li‐S batteries by preventing loss of soluble polysulfides, whereas issues related to insoluble discharge products, Li₂S₂ and Li₂S, have been underestimated. A facile and mild method, diazotization, that enables uniform functionalization on the surface of ordered mesoporous carbon (CMK‐3) with aniline functional groups while not deteriorating the original CMK‐3 microstructure is demonstrated. The aniline groups possess favorable interactions with insoluble discharge products. Thus, they homogeneously distribute the insoluble discharge products during cycling. The proposed materials exhibit outstanding electrochemical properties with regard to stability (920 mAh g^?1 at 0.2 C after 100 cycles) and rate capability (814 mAh g^?1 at 1 C) when evaluated as a cathode material for Li‐S batteries.     

Research Progress on Negative Electrodes for Practical Li‐Ion Batteries: Beyond Carbonaceous Anodes

Research activities related to the development of negative electrodes for construction of high‐performance Li‐ion batteries (LIBs) with conventional cathodes such as LiCoO₂, LiFePO₄, and LiMn₂O₄ are described. The anode materials are classified in to three main categories, insertion, conversion, and alloying type, based on their reactivity with Li. Although numerous materials have been proposed (i.e., for half‐cell assembly), few of them have reached commercial applications, apart from graphite, Li₄Ti₅O₁₂, Si, and Sn‐Co‐C. This clearly demonstrates that full‐cell studies are desperately needed rather than just characterizing materials in half‐cell assemblies. Additionally, the performance of such anodes in practical Li‐ion configurations (full‐cell) is much more important than merely proposing materials for LIBs. Irreversible capacity loss, huge volume variation, unstable solid electrolyte interface layer formation, and poor cycleability are the main issues for conversion and alloy type anodes. This review addresses how best to circumvent the mentioned issues during the construction of Li‐ion cells and the future prospects of such anodes are described in detail.     

广西唇柱苣苔属(苦苣苔科)一新变种——光华唇柱苣苔

记载了广西苦苣苔科Gesneriaceae一新变种——光华唇柱苣苔Chirita tribracteata、W．T.Wang var.zhuana Z．Y．Li,Q．Xing＆Y．B．Li。该变种与原变种不同在于叶大而厚,边缘具圆齿或牙齿,叶柄具宽翅,苞片宽倒卵形或倒披针形,有锯齿,花冠淡紫色,喉部具黄色纵纹。     

浙江天目地黄2新变型

描述了产于浙江临安的天目地黄2个新变型--白花天目地黄(Rehmannia chingii Li f.albi flora G.Y.Liet D.D.Ma)和紫斑白花天日地黄(R.chingii Li f.purpureo-punctata G.Y.Li et G.H.Xia),它们与原变型的主要区别为花冠白色;前者喉部淡黄色,后者喉部具紫色斑点.     

趋磁细菌W M-1 的培养条件优化研究

采用正交设计实验法研究了趋磁细菌WM-1产磁性细胞的培养条件。并利用L16(44)方案,用16个实验完成了4种培养条件、4个水平的优化工作。研究结果表明,培养基的pH值是影响趋磁细菌WM-1产磁性细胞的重要因素,正交实验结果在90％的置信区间可信。在最优的培养条件下,即pH为7．0,氧气的浓度为4％,m酒石酸:m琥珀酸为1:1,NaNO3 100 mg l-1条件下,磁性细胞的浓度提高到6．5×107 cells ml-1,比优化前提高了约8．3％．趋磁细菌WM-1磁滞回线的测量表明,Hc=230 Oe,Ms=0．9 emu／g dry wt．Cells,及Mr／Ms=0．50。