bluuebunny/crossref_metadata_2025 huggingface dataset:
Homology-directed repair in rodent zygotes using Cas9 and TALEN engineered proteins
Authors: Ménoret Séverine , De Cian Anne , Tesson Laurent , Remy Séverine , Usal Claire , Boulé Jean-Baptiste , Boix Charlotte , Fontanière Sandra , Crénéguy Alison , Nguyen Tuan H. , Brusselle Lucas , Thinard Reynald , Gauguier Dominique , Concordet Jean-Paul , Cherifi Yacine , Fraichard Alexandre , Giovannangeli Carine , Anegon Ignacio
Published: October 2015

The generation of genetically-modified organisms has been revolutionized by the development of new genome editing technologies based on the use of gene-specific nucleases, such as meganucleases, ZFNs, TALENs and CRISPRs-Cas9 systems. The most rapid and cost-effective way to generate genetically-modified animals is by microinjection of the nucleic acids encoding gene-specific nucleases into zygotes. However, the efficiency of the procedure can still be improved. In this work we aim to increase the efficiency of CRISPRs-Cas9 and TALENs homology-directed repair by using TALENs and Cas9 proteins, instead of mRNA, microinjected into rat and mouse zygotes along with long or short donor DNAs. We observed that Cas9 protein was more efficient at homology-directed repair than mRNA, while TALEN protein was less efficient than mRNA at inducing homology-directed repair. Our results indicate that the use of Cas9 protein could represent a simple and practical methodological alternative to Cas9 mRNA in the generation of genetically-modified rats and mice as well as probably some other mammals.
Sgf73, a subunit of SAGA complex, is required for the assembly of RITS complex in fission yeast
Authors: Deng Xiaolong , Zhou Huan , Zhang Guiping , Wang Wenchao , Mao Langyong , Zhou Xing , Yu Yao , Lu Hong
Published: October 2015

RNA interference (RNAi) is a widespread gene-silencing mechanism and is required for heterochromatin assembly in a variety of organisms. The RNA-induced transcriptional silencing complex (RITS), composed of Ago1, Tas3 and Chp1, is a key component of RNAi machinery in fission yeast that connects short interference RNA (siRNA) and heterochromatin formation. However, the process by which RITS is assembled is not well understood. Here, we identified Sgf73, a subunit of the SAGA co-transcriptional complex, is required for pericentromeric heterochromatin silencing and the generation of siRNA. This novel role of Sgf73 is independent of enzymatic activities or structural integrity of SAGA. Instead, Sgf73 is physically associated with Ago1 and Chp1. The interactions among the subunits of the RITS, including those between Tas3 and Chp1, between Chp1 and Ago1, between Ago1 and Tas3, were all impaired by the deletion of sgf73+. Consistently, the recruitment of Ago1 and Chp1 to the pericentromeric region was abolished in sgf73Δ cells. Our study unveils a moonlighting function of a SAGA subunit. It suggests Sgf73 is a novel factor that promotes assembly of RITS and RNAi-mediated heterochromatin formation.
Exfoliation of large-area transition metal chalcogenide single layers
Authors: Magda Gábor Zsolt , Pető János , Dobrik Gergely , Hwang Chanyong , Biró László P. , Tapasztó Levente
Published: October 2015

Isolating large-areas of atomically thin transition metal chalcogenide crystals is an important but challenging task. The mechanical exfoliation technique can provide single layers of the highest structural quality, enabling to study their pristine properties and ultimate device performance. However, a major drawback of the technique is the low yield and small (typically < 10 μm) lateral size of the produced single layers. Here, we report a novel mechanical exfoliation technique, based on chemically enhanced adhesion, yielding MoS2 single layers with typical lateral sizes of several hundreds of microns. The idea is to exploit the chemical affinity of the sulfur atoms that can bind more strongly to a gold surface than the neighboring layers of the bulk MoS2 crystal. Moreover, we found that our exfoliation process is not specific to MoS2, but can be generally applied for various layered chalcogenides including selenites and tellurides, providing an easy access to large-area 2D crystals for the whole class of layered transition metal chalcogenides.
An improved chloride-conducting channelrhodopsin for light-induced inhibition of neuronal activity in vivo
Authors: Wietek Jonas , Beltramo Riccardo , Scanziani Massimo , Hegemann Peter , Oertner Thomas G. , Wiegert J. Simon
Published: October 2015

Channelrhodopsins are light-gated cation channels that have been widely used for optogenetic stimulation of electrically excitable cells. Replacement of a glutamic acid in the central gate with a positively charged amino acid residue reverses the ion selectivity and produces chloride-conducting ChRs (ChloCs). Expressed in neurons, published ChloCs produced a strong shunting effect but also a small, yet significant depolarization from the resting potential. Depending on the state of the neuron, the net result of illumination might therefore be inhibitory or excitatory with respect to action potential generation. Here we report two additional amino acid substitutions that significantly shift the reversal potential of improved ChloC (iChloC) to the reversal potential of endogenous GABAA receptors. As a result, light-evoked membrane depolarization was strongly reduced and spike initiation after current injection or synaptic stimulation was reliably inhibited in iChloC-transfected neurons in vitro. In the primary visual cortex of anesthetized mice, activation of iChloC suppressed spiking activity evoked by visual stimulation. Due to its high operational light sensitivity, iChloC makes it possible to inhibit neurons in a large volume of brain tissue from a small, point-like light source.
Microscopic basis for the band engineering of Mo1−xWxS2-based heterojunction
Authors: Yoshida Shoji , Kobayashi Yu , Sakurada Ryuji , Mori Shohei , Miyata Yasumitsu , Mogi Hiroyuki , Koyama Tomoki , Takeuchi Osamu , Shigekawa Hidemi
Published: October 2015

Transition-metal dichalcogenide layered materials, consisting of a transition-metal atomic layer sandwiched by two chalcogen atomic layers, have been attracting considerable attention because of their desirable physical properties for semiconductor devices and a wide variety of pn junctions, which are essential building blocks for electronic and optoelectronic devices, have been realized using these atomically thin structures. Engineering the electronic/optical properties of semiconductors by using such heterojunctions has been a central concept in semiconductor science and technology. Here, we report the first scanning tunneling microscopy/spectroscopy (STM/STS) study on the electronic structures of a monolayer WS2/Mo1−xWxS2 heterojunction that provides a tunable band alignment. The atomically modulated spatial variation in such electronic structures, i.e., a microscopic basis for the band structure of a WS2/Mo1−xWxS2 heterojunction, was directly observed. The macroscopic band structure of Mo1−xWxS2 alloy was well reproduced by the STS spectra averaged over the surface. An electric field of as high as 80 × 106 Vm−1 was observed at the interface for the alloy with x = 0.3, verifying the efficient separation of photoexcited carriers at the interface.
Comparison of carbon-sulfur and carbon-amine bond in therapeutic drug: 4β-S-aromatic heterocyclic podophyllum derivatives display antitumor activity
Authors: Li Jian-Long , Zhao Wei , Zhou Chen , Zhang Ya-Xuan , Li Hong-Mei , Tang Ya-Ling , Liang Xin-Hua , Chen Tao , Tang Ya-Jie
Published: October 2015

Herein is a first effort to systematically study the significance of carbon-sulfur (C-S) and carbon-amine (C-NH) bonds on the antitumor proliferation activity of podophyllum derivatives and their precise mechanism of apoptosis. Compared with the derivative modified by a C-NH bond, the derivative modified by a C-S bond exhibited superior antitumor activity, the inhibition activity of target proteins tubulin or Topo II, cell cycle arrest and apoptosis induction. Antitumor mechanistic studies showed that the death receptor and the mitochondrial apoptotic pathways were simultaneously activated by the C-S bond modified aromatic heterocyclic podophyllum derivatives with a higher cellular uptake percentage of 60–90% and induction of a higher level of reactive oxygen species (ROS). Only the mitochondrial apoptotic pathway was activated by the C-NH bond modified aromatic heterocyclic podophyllum derivatives, with a lower cellular uptake percentage of 40–50%. This study provided insight into effects of the C-S and C-NH bond modification on the improvement of the antitumor activity of Podophyllum derivatives.
Enzyme-linked DNA dendrimer nanosensors for acetylcholine
Authors: Walsh Ryan , Morales Jennifer M. , Skipwith Christopher G. , Ruckh Timothy T. , Clark Heather A.
Published: October 2015

It is currently difficult to measure small dynamics of molecules in the brain with high spatial and temporal resolution while connecting them to the bigger picture of brain function. A step towards understanding the underlying neural networks of the brain is the ability to sense discrete changes of acetylcholine within a synapse. Here we show an efficient method for generating acetylcholine-detecting nanosensors based on DNA dendrimer scaffolds that incorporate butyrylcholinesterase and fluorescein in a nanoscale arrangement. These nanosensors are selective for acetylcholine and reversibly respond to levels of acetylcholine in the neurophysiological range. This DNA dendrimer architecture has the potential to overcome current obstacles to sensing in the synaptic environment, including the nanoscale size constraints of the synapse and the ability to quantify the spatio-temporal fluctuations of neurotransmitter release. By combining the control of nanosensor architecture with the strategic placement of fluorescent reporters and enzymes, this novel nanosensor platform can facilitate the development of new selective imaging tools for neuroscience.
Epigenetic silencing of the XAF1 gene is mediated by the loss of CTCF binding
Authors: Victoria-Acosta Georgina , Vazquez-Santillan Karla , Jimenez-Hernandez Luis , Muñoz-Galindo Laura , Maldonado Vilma , Martinez-Ruiz Gustavo Ulises , Melendez-Zajgla Jorge
Published: October 2015

XAF1 is a tumour suppressor gene that compromises cell viability by modulating different cellular events such as mitosis, cell cycle progression and apoptosis. In cancer, the XAF1 gene is commonly silenced by CpG-dinucleotide hypermethylation of its promoter. DNA demethylating agents induce transcriptional reactivation of XAF1, sensitizing cancer cells to therapy. The molecular mechanisms that mediate promoter CpG methylation have not been previously studied. Here, we demonstrate that CTCF interacts with the XAF1 promoter in vivo in a methylation-sensitive manner. By transgene assays, we demonstrate that CTCF mediates the open-chromatin configuration of the XAF1 promoter, inhibiting both CpG-dinucleotide methylation and repressive histone posttranslational modifications. In addition, the absence of CTCF in the XAF1 promoter inhibits transcriptional activation induced by well-known apoptosis activators. We report for the first time that epigenetic silencing of the XAF1 gene is a consequence of the loss of CTCF binding.
On the self-damping nature of densification in photonic sintering of nanoparticles
Authors: MacNeill William , Choi Chang-Ho , Chang Chih-Hung , Malhotra Rajiv
Published: October 2015

Sintering of nanoparticle inks over large area-substrates is a key enabler for scalable fabrication of patterned and continuous films, with multiple emerging applications. The high speed and ambient condition operation of photonic sintering has elicited significant interest for this purpose. In this work, we experimentally characterize the temperature evolution and densification in photonic sintering of silver nanoparticle inks, as a function of nanoparticle size. It is shown that smaller nanoparticles result in faster densification, with lower temperatures during sintering, as compared to larger nanoparticles. Further, high densification can be achieved even without nanoparticle melting. Electromagnetic Finite Element Analysis of photonic heating is coupled to an analytical sintering model, to examine the role of interparticle neck growth in photonic sintering. It is shown that photonic sintering is an inherently self-damping process, i.e., the progress of densification reduces the magnitude of subsequent photonic heating even before full density is reached. By accounting for this phenomenon, the developed coupled model better captures the experimentally observed sintering temperature and densification as compared to conventional photonic sintering models. Further, this model is used to uncover the reason behind the experimentally observed increase in densification with increasing weight ratio of smaller to larger nanoparticles.
Role of JAK-STAT signaling in maturation of phagosomes containing Staphylococcus aureus
Authors: Zhu Fei , Zhou Yadong , Jiang Chunxia , Zhang Xiaobo
Published: October 2015

Phagocytosis is a required mechanism for the defense against pathogens. Staphylococcus aureus, an important bacterial pathogen, can promptly escape from phagosomes and proliferate within the cytoplasm of host. However, the mechanism of phagocytosis against S. aureus has not been intensively investigated. In this study, the S. aureus was engulfed by macrophages (RAW264.7 cells) but not digested by the cells, suggesting that the phagosomes did not maturate in macrophages. Further investigation revealed that peptidoglycan (PG) induced the phagosome maturation of macrophages, resulting in the eradication of S. aureus. Genome-wide analysis and quantitative real-time PCR indicated that the JAK-STAT pathway was activated by PG during the phagosome maturation of macrophages against S. aureus. This finding presented that the PG-activated JAK-STAT pathway was required for phagosome maturation. Therefore, our study contributed evidence that revealed a novel aspect of PG-triggered JAK-STAT pathway in the phagosome maturation of macrophages.
Ultrasensitive nonlinear absorption response of large-size topological insulator and application in low-threshold bulk pulsed lasers
Authors: Xu Jin-Long , Sun Yi-Jian , He Jing-Liang , Wang Yan , Zhu Zhao-Jie , You Zhen-Yu , Li Jian-Fu , Chou Mitch M. C. , Lee Chao-Kuei , Tu Chao-Yang
Published: October 2015

Dirac-like topological insulators have attracted strong interest in optoelectronic application because of their unusual and startling properties. Here we report for the first time that the pure topological insulator Bi2Te3 exhibited a naturally ultrasensitive nonlinear absorption response to photoexcitation. The Bi2Te3 sheets with lateral size up to a few micrometers showed extremely low saturation absorption intensities of only 1.1 W/cm2 at 1.0 and 1.3 μm, respectively. Benefiting from this sensitive response, a Q-switching pulsed laser was achieved in a 1.0 μm Nd:YVO4 laser where the threshold absorbed pump power was only 31 mW. This is the lowest threshold in Q-switched solid-state bulk lasers to the best of our knowledge. A pulse duration of 97 ns was observed with an average power of 26.1 mW. A Q-switched laser at 1.3 μm was also realized with a pulse duration as short as 93 ns. Moreover, the mode locking operation was demonstrated. These results strongly exhibit that Bi2Te3 is a promising optical device for constructing broadband, miniature and integrated high-energy pulsed laser systems with low power consumption. Our work clearly points out a significantly potential avenue for the development of two-dimensional-material-based broadband ultrasensitive photodetector and other optoelectronic devices.
Habitat fragmentation is associated to gut microbiota diversity of an endangered primate: implications for conservation
Authors: Barelli Claudia , Albanese Davide , Donati Claudio , Pindo Massimo , Dallago Chiara , Rovero Francesco , Cavalieri Duccio , Tuohy Kieran Michael , Hauffe Heidi Christine , De Filippo Carlotta
Published: October 2015

The expansion of agriculture is shrinking pristine forest areas worldwide, jeopardizing the persistence of their wild inhabitants. The Udzungwa red colobus monkey (Procolobus gordonorum) is among the most threatened primate species in Africa. Primarily arboreal and highly sensitive to hunting and habitat destruction, they provide a critical model to understanding whether anthropogenic disturbance impacts gut microbiota diversity. We sampled seven social groups inhabiting two forests (disturbed vs. undisturbed) in the Udzungwa Mountains of Tanzania. While Ruminococcaceae and Lachnospiraceae dominated in all individuals, reflecting their role in extracting energy from folivorous diets, analysis of genus composition showed a marked diversification across habitats, with gut microbiota α-diversity significantly higher in the undisturbed forest. Functional analysis suggests that such variation may be associated with food plant diversity in natural versus human-modified habitats, requiring metabolic pathways to digest xenobiotics. Thus, the effects of changes in gut microbiota should not be ignored to conserve endangered populations.
Unconventional pairings of spin-orbit coupled attractive degenerate Fermi gas in a one-dimensional optical lattice
Authors: Liang Junjun , Zhou Xiaofan , Chui Pak Hong , Zhang Kuang , Gu Shi-jian , Gong Ming , Chen Gang , Jia Suotang
Published: October 2015

Understanding novel pairings in attractive degenerate Fermi gases is crucial for exploring rich superfluid physics. In this report, we reveal unconventional pairings induced by spin-orbit coupling (SOC) in a one-dimensional optical lattice, using a state-of-the-art density-matrix renormalization group method. When both bands are partially occupied, we find a strong competition between the interband Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) and intraband Bardeen-Cooper-Schrieffer (BCS) pairings. In particular, for the weak and moderate SOC strengths, these two pairings can coexist, giving rise to a new phase called the FFLO-BCS phase, which exhibits a unique three-peak structure in pairing momentum distribution. For the strong SOC strength, the intraband BCS pairing always dominates in the whole parameter regime, including the half filling. We figure out the whole phase diagrams as functions of filling factor, SOC strength and Zeeman field. Our results are qualitatively different from recent mean-field predictions. Finally, we address that our predictions could be observed in a weaker trapped potential.
Clinical features of rheumatoid arthritis-associated interstitial lung disease
Authors: Wang Ting , Zheng Xing-Ju , Liang Bin-Miao , Liang Zong-An
Published: October 2015

Interstitial lung disease (ILD) is the most common extra-articular manifestations of rheumatoid arthritis (RA) in the lung. This study aimed to identify clinical features of RA-associated ILD (RA-ILD). Patients with RA were retrospectively enrolled and sub-classified as RA-ILD or RA without ILD based on high-resolution computed tomography imaging. Pulmonary function testing parameters and levels of RA-related biomarkers, tumour markers and acute-phase proteins were compared between the two groups. Logistic regression model was used to assess the strength of association between RA-ILD and clinical features of interest. Receiver operating characteristic analysis was performed to assess potential predictive value of clinical features for detecting RA-ILD. Comparison analysis indicated that the percentage of predicted value of total lung capacity, inspiratory capacity and diffusion capacity of the lung for carbon monoxide (DLCO) were reduced in patients with RA-ILD. Tumour markers CA15–3 and CA125 were increased in patients with RA-ILD. Logistic regression analysis revealed that decreased DLCO was related to the increased likelihood of RA-ILD (OR = 0.94, 95%CI = [0.91, 0.98]). The cut-off point at 52.95 percent of predicted value could sensitively discriminate RA patients with or without ILD. Our study suggested that DLCO value could be a useful tool for detecting ILD in patients with RA.
Household physical activity and cancer risk: a systematic review and dose-response meta-analysis of epidemiological studies
Authors: Shi Yun , Li Tingting , Wang Ying , Zhou Lingling , Qin Qin , Yin Jieyun , Wei Sheng , Liu Li , Nie Shaofa
Published: October 2015

Controversial results of the association between household physical activity and cancer risk were reported among previous epidemiological studies. We conducted a meta-analysis to investigate the relationship of household physical activity and cancer risk quantitatively, especially in dose-response manner. PubMed, Embase, Web of science and the Cochrane Library were searched for cohort or case-control studies that examined the association between household physical activity and cancer risks. Random–effect models were conducted to estimate the summary relative risks (RRs), nonlinear or linear dose–response meta-analyses were performed to estimate the trend from the correlated log RR estimates across levels of household physical activity quantitatively. Totally, 30 studies including 41 comparisons met the inclusion criteria. Total cancer risks were reduced 16% among the people with highest household physical activity compared to those with lowest household physical activity (RR = 0.84, 95% CI = 0.76–0.93). The dose-response analyses indicated an inverse linear association between household physical activity and cancer risk. The relative risk was 0.98 (95% CI = 0.97–1.00) for per additional 10 MET-hours/week and it was 0.99 (95% CI = 0.98–0.99) for per 1 hour/week increase. These findings provide quantitative data supporting household physical activity is associated with decreased cancer risk in dose-response effect.
Direct regulation of the natural competence regulator gene tfoX by cyclic AMP (cAMP) and cAMP receptor protein (CRP) in Vibrios
Authors: Wu Rui , Zhao Meng , Li Jing , Gao He , Kan Biao , Liang Weili
Published: October 2015

TfoX (Sxy) and CRP are two important competence activators. The link betweentfoXand CRP has been shown inH. influenzabut lacking evidence of direct interaction. Recently a Sxy-dependent CRP (CRP-S) site autoregulating Sxy was reported inE. coli. Here, we show that the cAMP-CRP complex transcriptionally regulatestfoXexpression through multiple canonical CRP (CRP-N) sites inVibrios.This conclusion is supported by an analysis of thetfoXmRNA levels andtfoXtranscriptional reporter fusions. The reduced expression oftfoXVCwas restored by trans-complementation ofcrpin ∆crpand by exogenous cAMP in ∆cya. A promoter deletion analysis and the site-directed mutagenesis of the putative CRP-N sites revealed the presence of two functional CRP-N sites. The direct binding of cAMP-CRP to thetfoXVCpromoter was demonstrated by EMSA assays. Additionally, the transcriptional start site (TSS) oftfoXVFinV. fluvialiswas determined and −10/−35 regions were predicted. Further comparison of thetfoXpromoter inVibriosrevealed the existence of similar −10 motifs and putative CRP-N sites, indicating the conserved mechanism of CRP regulation ontfoX. Our study demonstrates the direct binding of the cAMP-CRP complex totfoXpromoter and broadens the understanding of the molecular mechanism regulatingtfoXinVibrios.
Spatial nitrifications of microbial processes during composting of swine, cow and chicken manure
Authors: Wang Ke , Li Weiguang , Li Xiangkun , Ren Nanqi
Published: October 2015

Composting is a widely-used method to recycle the nutrients in livestock manure for agriculture. The spatial stratifications of microbial processes inside the manure particle that determine organic and nitrogen transformation are virtually unclear. Here, we show the evolution of the interior microenvironment of swine, cow and chicken manure by using microelectrodes during forced-aeration composting. Composting has generally been regarded as an aerobic bioprocess, however, the long-existing of a large anoxic zone inside these manures was confirmed during the active phase in this study. The profile of the oxidation–reduction potential dramatically decreased first and then gradually increased. The spatial difference in the ammonia concentration was not significant, but nitrate concentration continuously decreased with depth. The anoxic condition within the manure particle was demonstrated to be a primary cause of the severe ammonia emission and the long composting period. These founding provided a new insight toward “aerobic” composting process and a sound foundation for the development of efficient composting technology.
Reversibly Switching Silver Hierarchical Structures via Reaction Kinetics
Authors: Liu Jianmei , Yang Tao , Li Chengxiang , Dai Jinhui , Han Yongsheng
Published: October 2015

Here we report a study on controllable synthesis of hierarchical silver structures via regulating reaction kinetics. Silver particles with various morphologies are synthesized by a solution-based reduction approach at the addition of amino acids. The amino acid is used to coordinate with silver ions to slow down the reduction of silver ions. With the increase of glycine concentration, the morphologies of silver particles switch from dendrites, to flowers and to compacted spheres, which is attributed to the decrease of reaction rate as a result of the coordination. Three more amino acids are examined and confirms the role of reaction kinetic in shaping silver particles. Furthermore, by increasing the concentration of the reductant, the silver morphologies change from compact spheres to loose flowers as a result of the increase of reaction rate. Therefore the silver hierarchical structure can be reversibly switched by reaction kinetics. The silver particles synthesized are tested for surface enhanced Raman scattering (SERS) property and the dendritic particles present a remarkable SERS activity. This study shows that reaction kinetics is a powerful tool to tune hierarchical structures of silver particles, which is expected to be transferable to other material systems.
Target-Driven Evolution of Scorpion Toxins
Authors: Zhang Shangfei , Gao Bin , Zhu Shunyi
Published: October 2015

It is long known that peptide neurotoxins derived from a diversity of venomous animals evolve by positive selection following gene duplication, yet a force that drives their adaptive evolution remains a mystery. By using maximum-likelihood models of codon substitution, we analyzed molecular adaptation in scorpion sodium channel toxins from a specific species and found ten positively selected sites, six of which are located at the core-domain of scorpion α-toxins, a region known to interact with two adjacent loops in the voltage-sensor domain (DIV) of sodium channels, as validated by our newly constructed computational model of toxin-channel complex. Despite the lack of positive selection signals in these two loops, they accumulated extensive sequence variations by relaxed purifying selection in prey and predators of scorpions. The evolutionary variability in the toxin-bound regions of sodium channels indicates that accelerated substitutions in the multigene family of scorpion toxins is a consequence of dealing with the target diversity. This work presents an example of atypical co-evolution between animal toxins and their molecular targets, in which toxins suffered from more prominent selective pressure from the channels of their competitors. Our discovery helps explain the evolutionary rationality of gene duplication of toxins in a specific venomous species.
Ultra-high-resolution 3D digitalized imaging of the cerebral angioarchitecture in rats using synchrotron radiation
Authors: Zhang Meng-Qi , Zhou Luo , Deng Qian-Fang , Xie Yuan-Yuan , Xiao Ti-Qiao , Cao Yu-Ze , Zhang Ji-Wen , Chen Xu-Meng , Yin Xian-Zhen , Xiao Bo
Published: October 2015

The angioarchitecture is a fundamental aspect of brain development and physiology. However, available imaging tools are unsuited for non-destructive cerebral mapping of the functionally important three-dimensional (3D) vascular microstructures. To address this issue, we developed an ultra-high resolution 3D digitalized angioarchitectural map for rat brain, based on synchrotron radiation phase contrast imaging (SR-PCI) with pixel size of 5.92 μm. This approach provides a systematic and detailed view of the cerebrovascular anatomy at the micrometer level without any need for contrast agents. From qualitative and quantitative perspectives, the present 3D data provide a considerable insight into the spatial vascular network for whole rodent brain, particularly for functionally important regions of interest, such as the hippocampus, pre-frontal cerebral cortex and the corpus striatum. We extended these results to synchrotron-based virtual micro-endoscopy, thus revealing the trajectory of targeted vessels in 3D. The SR-PCI method for systematic visualization of cerebral microvasculature holds considerable promise for wider application in life sciences, including 3D micro-imaging in experimental models of neurodevelopmental and vascular disorders.
Whispering-gallery nanocavity plasmon-enhanced Raman spectroscopy
Authors: Zhang Jing , Li Jinxing , Tang Shiwei , Fang Yangfu , Wang Jiao , Huang Gaoshan , Liu Ran , Zheng Lirong , Cui Xugao , Mei Yongfeng
Published: October 2015

The synergy effect in nature could enable fantastic improvement of functional properties and associated effects. The detection performance of surface-enhanced Raman scattering (SERS) can be highly strengthened under the cooperation with other factors. Here, greatly-enhanced SERS detection is realized based on rolled-up tubular nano-resonators decorated with silver nanoparticles. The synergy effect between whispering-gallery-mode (WGM) and surface plasmon leads to an extra enhancement at the order of 105 compared to non-resonant flat SERS substrates, which can be well tuned by altering the diameter of micron- and nanotubes and the excitation laser wavelengths. Such synchronous and coherent coupling between plasmonics and photonics could lead to new principle and design for various sub-wavelength optical devices, e.g. plasmonic waveguides and hyperbolic metamaterials.
Switchable Ultrathin Quarter-wave Plate in Terahertz Using Active Phase-change Metasurface
Authors: Wang Dacheng , Zhang Lingchao , Gu Yinghong , Mehmood M. Q. , Gong Yandong , Srivastava Amar , Jian Linke , Venkatesan T. , Qiu Cheng-Wei , Hong Minghui
Published: October 2015

Metamaterials open up various exotic means to control electromagnetic waves and among them polarization manipulations with metamaterials have attracted intense attention. As of today, static responses of resonators in metamaterials lead to a narrow-band and single-function operation. Extension of the working frequency relies on multilayer metamaterials or different unit cells, which hinder the development of ultra-compact optical systems. In this work, we demonstrate a switchable ultrathin terahertz quarter-wave plate by hybridizing a phase change material, vanadium dioxide (VO2), with a metasurface. Before the phase transition, VO2 behaves as a semiconductor and the metasurface operates as a quarter-wave plate at 0.468 THz. After the transition to metal phase, the quarter-wave plate operates at 0.502 THz. At the corresponding operating frequencies, the metasurface converts a linearly polarized light into a circularly polarized light. This work reveals the feasibility to realize tunable/active and extremely low-profile polarization manipulation devices in the terahertz regime through the incorporation of such phase-change metasurfaces, enabling novel applications of ultrathin terahertz meta-devices.
Calcium in the Context of Dietary Sources and Metabolism
Authors: Buchowski Maciej S.
Published: October 2015

This chapter focuses on calcium in the context of dietary sources and providing bases of calcium metabolism in the human body. Calcium is an inorganic element essential to living cells present in the Earth's biosphere as a solid matter and aqueous solution. In humans, calcium is an essential constituent of bones and teeth where it supports structure. It is a key component of vascular calcification, and is necessary for activation catalytic and mechanical properties of proteins in key enzymes. Dietary sources of calcium include dairy and nondairy foods, fortified foods and supplements such as calcium carbonate and calcium citrate. Calcium is readily absorbed through the gastrointestinal tract by way of vitamin D3 action. Calcium forms complexes with some food components and this allows it to be absorbed alongside the food molecules. High gastric acidity also aids solubilization and absorption of calcium salts such as carbonate, sulfate, fluorite, and phosphate. In a neutral environment, the absorbability of calcium is influenced by other food components such as lactose, glucose, fatty acids, phosphorus, and oxalate that can bind to soluble calcium. Calcium balance is measured as the difference between the calcium absorbed and that which is excreted, for example in urine, feces and sweat. It is essential to maintain this balance in order to facilitate many physiological processes, ranging from cell signaling to maintenance of bone health. Calcium homeostasis is regulated by the interrelationship between intestinal calcium absorption, bone influx and efflux of calcium, and renal calcium excretion.
Calcium Digestibility Using In Vivo, In Vitro and Ex Vivo Techniques
Authors: Rossi F.
Published: October 2015

As for many other nutrients, Ca digestibility can be determined with in vitro, ex vivo and in vivo techniques. The first group of methods is mainly based on a HCl–pepsin attack, followed by pancreatin–bile extract hydrolysis. After this enzymatic digestion, the digested sample is centrifuged and the Ca in the surnatant represents the soluble fraction. If in the flask where the Ca-containing sample undergoes pancreatin–bile extract digestion, is put a dialysis tube containing water and NaHCO3, we could measure dialyzed Ca. The uptake of Ca by intestinal cells can be estimated supplementing the growth medium of differentiated human tumor cells (HT-29 or Caco-2) with the soluble or dialyzable fraction coming from the in vitro digestion. In vivo techniques include balance studies (both in humans and in animals), studies with labeled Ca or research with bone mineralization as the main endpoint.
Calcium-Fortified Soymilk: Function and Health Benefits
Authors: Stojanovska Lily , Ayyash Mutamed , Apostolopoulos Vasso
Published: October 2015

Calcium is an essential element to human bones where 99% of total calcium in the body is found in teeth and bones. Calcium is absorbed by active transport and passive diffusion across the intestinal mucosa. Calcium deficiency can lead to disorders like osteoporosis. Calcium is present in dairy foods and calcium-fortified products, such as soymilk. With increasing allergies to milk proteins in the last 2 decades, calcium in the diet has been reduced, leading to calcium deficiency. Soymilk has therefore become an alternative to milk and its products. However, the amount of calcium in soymilk is low, and therefore the need for calcium fortification. Soy products have played an integral part in the Asian diet for many centuries. In the western diet soy products are used due to their protein content, but more importantly for the health benefits in the prevention and treatment of chronic diseases, notably cancer, osteoporosis and heart disease. This chapter discusses the beneficial effects of soymilk in health and disease.
The Calcium-Sensing Receptor in Intestinal Cells
Authors: Hira Tohru , Nakajima Shingo , Hara Hiroshi
Published: October 2015

The calcium-sensing receptor (CaSR or CaR) was first identified in the bovine parathyroid gland. Its primary function is to regulate calcium homeostasis in the body. However, CaSR is expressed in a variety of tissues that are not directly related to calcium homeostasis. In addition to calcium ions, various compounds such as l-amino acids, polyamines, basic polypeptides, gamma glutamyl peptides, and other peptides, also activate CaSR in an allosteric manner. Its broad ligands and wide expression profile suggest multiple functions of CaSR in different tissues. This chapter reviews the functions of CaSR in the gastrointestinal tract. Specifically, a role for CaSR in luminal nutrient sensing in the enteroendocrine system is described.
Taste Cells and Calcium Signaling
Authors: Medler Kathryn F.
Published: October 2015

We use our sense of taste to determine if a potential food item should be consumed. Taste is activated when chemicals from potential nutrients activate the peripheral taste receptor cells in the mouth. Peripheral taste receptor cells depend on distinct calcium signals to generate appropriate cellular responses that relay taste information to the central nervous system. There are significant differences in the responses between taste cells, depending on what taste quality they detect. Some taste cells have conventional chemical synapses and rely on calcium influx through voltage-gated calcium channels. Other taste cells lack these synapses and depend on calcium release from stores to formulate an output signal. Regardless of the signaling pathway, taste cells all depend on calcium to form an appropriate output signal. This review will discuss the known differences between the taste signaling pathways and what is currently known about how these calcium signals are regulated. Emerging evidence suggests that diseases, such as obesity, can significantly alter taste-evoked calcium signals, which may lead to alterations in taste-dependent behaviors. Clearly, calcium signaling is a critical component of taste transduction and may be more complex than previously appreciated.
Pregnancy and Calcium
Authors: Alshaikh Belal , Yusuf Kamran
Published: October 2015

During normal human pregnancy, the fetus accumulates 30 g of calcium. To meet this fetal demand, major maternal adaptations in calcium metabolism take place. Most significant among these is doubling of intestinal calcium absorption during pregnancy associated with increased levels of 1,25-dihydroxyvitamin D3. In addition, there may be increased resorption of trabecular bone during pregnancy. This, however, is not associated with adverse long-term outcomes such as osteoporosis and fractures. Calcium is actively transported across the placenta by a complex and elaborate system of proteins, allowing the fetus to maintain calcium levels higher than the mother. The regulation of placental calcium transport is largely unknown. In mothers with sufficient intake of dietary calcium, these adaptations are considered adequate for the calcium needs of the mother and fetus and the need for supplemental calcium in these mothers is controversial. In mothers with a decreased intake of dietary calcium, calcium supplementation has been demonstrated to reduce the incidence of gestational hypertensive disease and preterm birth. Disorders of calcium metabolism during pregnancy such as hyper- and hypoparathroidism, may present diagnostic and management challenges due to the maternal adaptations in calcium metabolism. This chapter will review the calcium metabolism and adaptations that occur during pregnancy, followed by a discussion of pathological calcium states during pregnancy.
Dietary Calcium and Osteoprotegerin
Authors: Sun Dianjun , Yu Jun , Gao Yanhui , Li Yuanyuan
Published: October 2015

Calcium is an essential trace element of human body. It is both the constructor and regulator of the body, and the source of our human life. Osteoprotegerin (OPG) is a glycoprotein involved in bone metabolism and plays a regulatory role in the immune, the skeletal and the circulatory systems. In recent years, the level of circulating OPG has become an independent biomarker of cardiovascular disease, not only for patients with acute or chronic heart disease, but also for healthy people. Furthermore, OPG has been involved in various inflammations and is closely associated with diabetes mellitus and poor glycaemic control. In view of the function of calcium and the role of OPG in calcification, the potential interaction between dietary calcium and OPG deserves much attention.
Calcium in Critical Care
Authors: Youssef Dima , Amrein Karin
Published: October 2015

Nutrition is an essential part in the care of critically ill patients. Calcium is a major nutritional element, and is acquired mainly through food resources. Calcium is required in the control of many cellular mechanisms. Because of its vital importance, it is under strict control by PTH, other minerals and vitamin D. Any imbalance in its range may cause deleterious implications in many organ systems including arrhythmia, laryngeal spasms and death. As in critical illness the total calcium concentration may be changed by hypoalbuminemia and disorders of acid–base balance, the diagnosis of hypocalcemia should be based on ionized calcium levels. This chapter discusses the importance of calcium in general, with a focus on critical care, and presents the different manifestations and consequences patients may suffer when they are in a hypo- or hypercalcemic status. We also discuss the different treatment options.
Hypercalcemia: An Overview of its Pathology
Authors: Lumachi Franco , Basso Stefano M. M.
Published: October 2015

Calcium is essential for several human physiological processes, including the function of cellular membranes, nerves and muscles, enzymatic activities, and blood clotting. The endocrine control of Ca2+ is achieved by a homeostatic mechanism involving PTH, 1,25-dihydroxyvitamin D, and calcitonin, but other factors, such as FGF-23, TRPV5, and Klotho, regulate calcium metabolism. Hypercalcemia is a relatively common disorder largely related to primary hyperparathyroidism that accounts for approximately 80% of cases. Malignancy-associated hypercalcemia (MAH) is the most common metabolic disorder in malignancy, that can be observed in 10–15% of cancer patients. Two different mechanisms may lead to MAH. The so-called humoral hypercalcemia is largely caused by the secretion of parathyroid hormone-related protein (PTHrP) by the malignant cells. On the contrary, local osteolytic hypercalcemia is induced directly by cancer cells invading the bone leading to the degradation of mineral matrix. All patients with hypercalcemia require early diagnosis and treatment to prevent the development of serious mid- and long-term complications. These complications are now uncommon in patients with primary hyperparathyroidism, in whom effective parathyroidectomy leads to complete recovery, but they can be observed in cancer patients with cancer-related skeletal events.
Determination of trace levels of iron in serum samples of hepatitis B and C patients using dispersive liquid–liquid microextraction
Authors: Arain Salma Aslam , Kazi Tasneem Gul , Afridi Hassan Imran , Abbasi Abdul Rasool , Ullah Naeem , Panhwar Abdul Haleem , Siraj Saima
Published: October 2015

An environmentally friendly ionic liquid-based dispersive liquid–liquid microextraction method for the preconcentration of trace levels of iron in serum samples of hepatitis B and C patients, prior to its determination by flame atomic absorption spectrometry.
Surface engineering of macrophages with nucleic acid aptamers for the capture of circulating tumor cells
Authors: Sugimoto Shunsuke , Moriyama Rui , Mori Takeshi , Iwasaki Yasuhiko
Published: October 2015

Nucleic acid aptamers, which can bind to the membrane proteins of tumor cells, were immobilized on macrophages through a thiol–ene ‘click’ reaction. Through surface modifications, the tumor cell capture by macrophages was significantly induced.
Stability and its manifestation in the chemical and biological worlds
Authors: Pascal Robert , Pross Addy
Published: October 2015

A logical principle that connects Boltzmann's second law and Darwinian selection places biological systems within a general physical/chemical framework.
Efficient visible light-driven water oxidation catalyzed by an all-inorganic copper-containing polyoxometalate
Authors: Yu Li , Du Xiaoqiang , Ding Yong , Chen Hongli , Zhou Panpan
Published: October 2015

We report the first copper-containing POM catalyst [Cu5(OH)4(H2O)2(A-α-SiW9O33)2]10−(1) that catalyzes water oxidation under visible light. Multiple experiments confirm that1is an active and dominant catalyst during water oxidation.
Multicomponent kinetic analysis and theoretical studies on the phenolic intermediates in the oxidation of eugenol and isoeugenol catalyzed by laccase
Authors: Qi Yan-Bing , Wang Xiao-Lei , Shi Ting , Liu Shuchang , Xu Zhen-Hao , Li Xiqing , Shi Xuling , Xu Ping , Zhao Yi-Lei
Published: October 2015

Phenolic radicals in the oxidation of eugenol and isoeugenol undergo a hydrogen atom transfer pathway and a radical coupling pathway respectively.
A comparative first principles study on trivalent ion incorporated SSZ-13 zeolites
Authors: Wen Cui , Geng Lu , Han Lina , Wang Jiancheng , Chang Liping , Feng Gang , Kong Dejin , Liu Jianwen
Published: October 2015

The dispersion-corrected density functional theory has been used to study the trivalent ions B, Al, Ga, and Fe incorporated SSZ-13-type zeolites.
Ferromagnetic coupling in d1–d3 linear oxido-bridged heterometallic complexes: ground-state models of metal-to-metal charge transfer excited states
Authors: Huang Tao , Wu Xinyuan , Song Xiao , Xu Hao , Smirnova Tatyana I. , Weare Walter W. , Sommer Roger D.
Published: October 2015

Linear heterobimetallic oxido-bridged d1–d3 compounds are described which are proposed as models for magnetic coupling of MMCT excited states.
Assembly and stabilization of {E(cyclo-P3)2} (E = Sn, Pb) as a bridging ligand spanning two triaryloxyniobium units
Authors: Velian Alexandra , Cossairt Brandi M. , Cummins Christopher C.
Published: October 2015

The reaction chemistry of complexes (THF)0–2E[P3Nb(ODipp)3]2 (E = Sn, Pb; Dipp = 2,6-iPr2C6H3) featuring the metallophosphide ligand {E(cyclo-P3)2} is investigated.
Employing a new 12-connected topological open-framework copper borovanadate as an effective heterogeneous catalyst for oxidation of benzyl-alkanes
Authors: Feng Yuquan , Ding Chenghua , Fan Huitao , Zhong Zhiguo , Qiu Dongfang , Shi Hengzhen
Published: October 2015

The compound not only features the first 3-D copper(ii) borovanadate which possesses the largest ratio of TM2+ and borovanadate anion, but also displays highly catalytic activities for the oxidation of benzyl-alkanes.
Lithium sulfur batteries, a mechanistic review
Authors: Wild M. , O'Neill L. , Zhang T. , Purkayastha R. , Minton G. , Marinescu M. , Offer G. J.
Published: October 2015

Lithium sulfur batteries, review of current mechanistic understanding and the gap between experimentally derived mechanisms and those used for modelling.