Locomotion Generation and Motion Library Design for an Anguilliform Robotic Fish

In this paper, modeling, locomotion generation, motion library design and path planning for a real prototype of an Anguilliform robotic fish are presented. The robotic fish consists of four links and three joints, and the driving forces are the torques applied to the joints. Considering kinematic constraints and hydrodynamic forces, Lagrangian formulation is used to obtain the dynamic model of the fish. Using this model, three major locomotion patterns of Anguilliform fish, including forward locomotion, backward locomotion and turning locomotion are investigated. It is found that the fish exhibits different locomotion patterns by giving different reference joint angles, such as adding reversed phase difference, or adding deflections to the original reference angles. The results are validated by both simulations and experiments. Furthermore, the relations among the speed of the fish, angular frequency, undulation amplitude, phase difference, as well as the relationship between the turning radius and deflection angle are investigated. These relations provide an elaborated motion library that can be used for motion planning of the robotic fish.     

天然香料在化妆品中的应用现状

：随着人们对天然、绿色、安全性化妆品的日益需求,天然香料在化妆品中也随之被广泛应用。天然香料主要分为植物性天然香料和动物性天然香料。本文主要介绍了天然香料的定义及其分类,天然香料在化妆品中的应用以及国内外可用于化妆品的天然香料工业发展等,并且根据天然香料在化妆品中应用存在的问题,提出几点建议。其中,在对天然香料的定义和分类中,除了明确天然香料的定义外,还根据其中含有的不同类型和功效的成分,分为天然香料中的芳香成分、药用成分、营养成分和其他成分。天然香料在化妆品中的应用,主要介绍目前市场上应用最广泛的动物类天然香料以及花类、叶类和果实类等植物性天然香料。此外,从三方面对天然香料在化妆品中的应用提出建议,主要为新资源综合利用及开发,改进技术并提高天然香料产量和质量,开发治疗性、保健性天然化妆品等。     

实习护生学历与心理健康状况相关性研究

目的：了解不同学历实习护生心理健康状况及存在的心理健康问题,分析其与学历之间的关系,为实施干预提供依据。方法：采用症状自评量表（SCL-90）,对100名不同学历实习护生进行问卷调查。结果：不同学历实习护生SCL-90量表测试所得强迫症状、抑郁、焦虑、恐惧等因子分均高于常模组具体得分,不同学历SCL-90量表测试所得抑郁、焦虑、敌对、恐惧精神病性等因子分有差异。结论：强迫症状、抑郁、焦虑、敌对是不同学历实习护生最主要的心理问题,研究生、本科学历实习护生更为严重,不同学历心理问题的严重程度不同。     

孕期妇女钙含量与妊娠期高血压的相关性分析

目的：探讨孕期妇女钙含量与妊娠期高血压的相关性。方法：选取235例妊娠期高血压孕妇为观察组研究对象,抽取母体血清样本检测血清中微量元素钙的含量。另外选取200例正常妊娠孕妇为对照组,同样检测母血中钙的含量。比较两组孕妇的血钙含量,且对观察组孕妇进行补钙治疗后,检测其血压值的变化,探讨孕期妇女钙含量与妊娠期高血压的相关性。结果：观察组中轻度妊娠期高血压孕妇钙离子的平均浓度为（2．11±0．24）mmol／L,中度妊娠期高血压孕妇钙离子的平均浓度为（2．03±0．21）mmol／L,重度妊娠期高血压孕妇钙离子的平均浓度为（1．98±0．25）mmol／L。观察组中孕妇平均钙离子浓度为（2．05±0．22）mmol／L,而对照组中孕妇钙离子的平均浓度为（2．40±0．28）mmol／L。对照组孕妇钙离子浓度明显高于观察组孕妇（P〈0．05）。在观察组孕妇随着血压值的上升,血清钙离子浓度呈下降趋势（P〈0．05）。补钙治疗后的原轻度妊娠期高血压孕妇收缩压与舒张压较治疗前有所下降（P〈0．05）。中度及重度妊娠期高血压孕妇治疗后收缩压与舒张压较治疗前有明显下降（P〈0．01）。结论：妊娠期高血压的发生,可能与孕妇血钙含量有关,加强孕期微量元素钙的摄取,为控制妊娠期高血压的发生和发展提供了新的思路。     

A Quorum Sensing Small Volatile Molecule Promotes Antibiotic Tolerance in Bacteria

Bacteria can be refractory to antibiotics due to a sub-population of dormant cells, called persisters that are highly tolerant to antibiotic exposure. The low frequency and transience of the antibiotic tolerant “persister” trait has complicated elucidation of the mechanism that controls antibiotic tolerance. In this study, we show that 2’ Amino-acetophenone (2-AA), a poorly studied but diagnostically important small, volatile molecule produced by the recalcitrant gram-negative human pathogen Pseudomonas aeruginosa, promotes antibiotic tolerance in response to quorum-sensing (QS) signaling. Our results show that 2-AA mediated persister cell accumulation occurs via alteration of the expression of genes involved in the translational capacity of the cell, including almost all ribosomal protein genes and other translation-related factors. That 2-AA promotes persisters formation also in other emerging multi-drug resistant pathogens, including the non 2-AA producer Acinetobacter baumannii implies that 2-AA may play an important role in the ability of gram-negative bacteria to tolerate antibiotic treatments in polymicrobial infections. Given that the synthesis, excretion and uptake of QS small molecules is a common hallmark of prokaryotes, together with the fact that the translational machinery is highly conserved, we posit that modulation of the translational capacity of the cell via QS molecules, may be a general, widely distributed mechanism that promotes antibiotic tolerance among prokaryotes.     

Novel Structural and Functional Insights into M3 Muscarinic Receptor Dimer/Oligomer Formation

Class A G protein-coupled receptors (GPCRs) are able to form homodimers and/or oligomeric arrays. We recently proposed, based on bioluminescence resonance energy transfer studies with the M₃ muscarinic receptor (M3R), a prototypic class A GPCR, that the M3R is able to form multiple, structurally distinct dimers that are probably transient in nature (McMillin, S. M., Heusel, M., Liu, T., Costanzi, S., and Wess, J. (2011) J. Biol. Chem. 286, 28584–28598). To provide more direct experimental support for this concept, we employed a disulfide cross-linking strategy to trap various M3R dimeric species present in a native lipid environment (transfected COS-7 cells). Disulfide cross-linking studies were carried out with many mutant M3Rs containing single cysteine (Cys) substitutions within two distinct cytoplasmic M3R regions, the C-terminal portion of the second intracellular loop (i2) and helix H8 (H8). The pattern of cross-links that we obtained, in combination with molecular modeling studies, was consistent with the existence of two structurally distinct M3R dimer interfaces, one involving i2/i2 contacts (TM4-TM5-i2 interface) and the other one characterized by H8-H8 interactions (TM1-TM2-H8 interface). Specific H8-H8 disulfide cross-links led to significant impairments in M3R-mediated G protein activation, suggesting that changes in the structural orientation or mobility of H8 are critical for efficient receptor-G protein coupling. Our findings provide novel structural and functional insights into the mechanisms involved in M3R dimerization (oligomerization). Because the M3R shows a high degree of sequence similarity with many other class A GPCRs, our findings should be of considerable general interest.     

Coordinated Processing of 3′ Slipped (CAG)n/(CTG)n Hairpins by DNA Polymerases β and δ Preferentially Induces Repeat Expansions

Expansion of CAG/CTG trinucleotide repeats causes certain familial neurological disorders. Hairpin formation in the nascent strand during DNA synthesis is considered a major path for CAG/CTG repeat expansion. However, the underlying mechanism is unclear. We show here that removal or retention of a nascent strand hairpin during DNA synthesis depends on hairpin structures and types of DNA polymerases. Polymerase (pol) δ alone removes the 3′-slipped hairpin using its 3′-5′ proofreading activity when the hairpin contains no immediate 3′ complementary sequences. However, in the presence of pol β, pol δ preferentially facilitates hairpin retention regardless of hairpin structures. In this reaction, pol β incorporates several nucleotides to the hairpin 3′-end, which serves as an effective primer for the continuous DNA synthesis by pol δ, thereby leading to hairpin retention and repeat expansion. These findings strongly suggest that coordinated processing of 3′-slipped (CAG)_n/(CTG)_n hairpins by polymerases δ and β on during DNA synthesis induces CAG/CTG repeat expansions.     

Merkel Cell Polyomavirus Large T Antigen Disrupts Host Genomic Integrity and Inhibits Cellular Proliferation

Clonal integration of Merkel cell polyomavirus (MCV) DNA into the host genome has been observed in at least 80% of Merkel cell carcinoma (MCC). The integrated viral genome typically carries mutations that truncate the C-terminal DNA binding and helicase domains of the MCV large T antigen (LT), suggesting a selective pressure to remove this MCV LT region during tumor development. In this study, we show that MCV infection leads to the activation of host DNA damage responses (DDR). This activity was mapped to the C-terminal helicase-containing region of the MCV LT. The MCV LT-activated DNA damage kinases, in turn, led to enhanced p53 phosphorylation, upregulation of p53 downstream target genes, and cell cycle arrest. Compared to the N-terminal MCV LT fragment that is usually preserved in mutants isolated from MCC tumors, full-length MCV LT shows a decreased potential to support cellular proliferation, focus formation, and anchorage-independent cell growth. These apparently antitumorigenic effects can be reversed by a dominant-negative p53 inhibitor. Our results demonstrate that MCV LT-induced DDR activates p53 pathway, leading to the inhibition of cellular proliferation. This study reveals a key difference between MCV LT and simian vacuolating virus 40 LT, which activates a DDR but inhibits p53 function. This study also explains, in part, why truncation mutations that remove the MCV LT C-terminal region are necessary for the oncogenic progression of MCV-associated cancers.