bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of temperature on the fracture toughness of anisotropic shale and other rocks
Authors: Chandler Michael R. , Meredith Philip G. , Brantut Nicolas , Crawford Brian R.
Published: April 2017

Fracture toughness was measured for a range of rock materials as a function of temperature between ambient temperature and 150°C. Measurements were made along all three principal crack orientations for the transversely isotropic Mancos shale and in single orientations for the more isotropic Darley Dale sandstone, Indiana limestone and Lanhelin granite. Fracture toughness was measured using a modified short-rod method with the sample and loading equipment enclosed within an elevated temperature chamber. A slight increase in
K
Ic
was observed in Lanhelin granite with increasing temperatures up to 54°C, before a steady decrease at higher temperatures. For the sandstone and limestone, little change was observed in
K
Ic
over the studied temperature range. In measurements on Mancos shale at elevated temperatures. Fracture toughness was seen to increase slightly with increasing temperature in the arrester orientation over this range, while remaining constant in the other two orientations. These observations can be explained in terms of the development of thermally induced microfractures parallel to the bedding planes in this material. A bimodal distribution of K
Ic
values in the short-transverse orientation was not observed, as it has been for previously published measurements at ambient conditions.
Gas transport properties through intact and fractured Callovo-Oxfordian mudstones
Authors: Harrington Jon F. , Cuss Robert J. , Talandier Jean
Published: April 2017

A series of controlled water and gas experiments was undertaken on samples of Callovo-Oxfordian (COx) mudstone using a synthetic fluid and helium gas. Data from this study demonstrate that the advective movement of gas through COx is accompanied by dilation of the original fabric (i.e. the formation of pressure-induced microfissures) at gas pressures significantly below that of the minimum principal stress. Flow occurs through a local network of unstable pathways, the properties of which vary temporally and spatially within the mudstone. The coupling of variables results in the development of significant time-dependent effects affecting many aspects of COx behaviour, from the gas breakthrough time to the control of deformation processes. Variations in gas entry, breakthrough and steady-state pressures may result from the arbitrary nature of the flow pathways and/or microstructural heterogeneity. Under these conditions, the data suggest that gas flow is along pressure-induced preferential pathways, where permeability is a dependent variable related to the number, width and aperture distributions of these features. This has important implications for modelling gas migration through low permeability, clay-rich materials.
Light-Addressable Potentiometric Sensors for Quantitative Spatial Imaging of Chemical Species
Authors: Yoshinobu Tatsuo , Miyamoto Ko-ichiro , Werner Carl Frederik , Poghossian Arshak , Wagner Torsten , Schöning Michael J.
Published: April 2017

A light-addressable potentiometric sensor (LAPS) is a semiconductor-based chemical sensor, in which a measurement site on the sensing surface is defined by illumination. This light addressability can be applied to visualize the spatial distribution of pH or the concentration of a specific chemical species, with potential applications in the fields of chemistry, materials science, biology, and medicine. In this review, the features of this chemical imaging sensor technology are compared with those of other technologies. Instrumentation, principles of operation, and various measurement modes of chemical imaging sensor systems are described. The review discusses and summarizes state-of-the-art technologies, especially with regard to the spatial resolution and measurement speed; for example, a high spatial resolution in a submicron range and a readout speed in the range of several tens of thousands of pixels per second have been achieved with the LAPS. The possibility of combining this technology with microfluidic devices and other potential future developments are discussed.
Chemical and Biological Dynamics Using Droplet-Based Microfluidics
Authors: Dressler Oliver J. , Casadevall i Solvas Xavier , deMello Andrew J.
Published: April 2017

Recent years have witnessed an increased use of droplet-based microfluidic techniques in a wide variety of chemical and biological assays. Nevertheless, obtaining dynamic data from these platforms has remained challenging, as this often requires reading the same droplets (possibly thousands of them) multiple times over a wide range of intervals (from milliseconds to hours). In this review, we introduce the elemental techniques for the formation and manipulation of microfluidic droplets, together with the most recent developments in these areas. We then discuss a wide range of analytical methods that have been successfully adapted for analyte detection in droplets. Finally, we highlight a diversity of studies where droplet-based microfluidic strategies have enabled the characterization of dynamic systems that would otherwise have remained unexplorable.
Tailored Surfaces/Assemblies for Molecular Plasmonics and Plasmonic Molecular Electronics
Authors: Lacroix Jean-Christophe , Martin Pascal , Lacaze Pierre-Camille
Published: April 2017

Molecular plasmonics uses and explores molecule–plasmon interactions on metal nanostructures for spectroscopic, nanophotonic, and nanoelectronic devices. This review focuses on tailored surfaces/assemblies for molecular plasmonics and describes active molecular plasmonic devices in which functional molecules and polymers change their structural, electrical, and/or optical properties in response to external stimuli and that can dynamically tune the plasmonic properties. We also explore an emerging research field combining molecular plasmonics and molecular electronics.
Engineering and In Vivo Applications of Riboswitches
Authors: Hallberg Zachary F. , Su Yichi , Kitto Rebekah Z. , Hammond Ming C.
Published: April 2017

Riboswitches are common gene regulatory units mostly found in bacteria that are capable of altering gene expression in response to a small molecule. These structured RNA elements consist of two modular subunits: an aptamer domain that binds with high specificity and affinity to a target ligand and an expression platform that transduces ligand binding to a gene expression output. Significant progress has been made in engineering novel aptamer domains for new small molecule inducers of gene expression. Modified expression platforms have also been optimized to function when fused with both natural and synthetic aptamer domains. As this field expands, the use of these privileged scaffolds has permitted the development of tools such as RNA-based fluorescent biosensors. In this review, we summarize the methods that have been developed to engineer new riboswitches and highlight applications of natural and synthetic riboswitches in enzyme and strain engineering, in controlling gene expression and cellular physiology, and in real-time imaging of cellular metabolites and signals.
Emerging Frontiers of Neuroengineering: A Network Science of Brain Connectivity
Authors: Bassett Danielle S. , Khambhati Ankit N. , Grafton Scott T.
Published: April 2017

Neuroengineering is faced with unique challenges in repairing or replacing complex neural systems that are composed of many interacting parts. These interactions form intricate patterns over large spatiotemporal scales and produce emergent behaviors that are difficult to predict from individual elements. Network science provides a particularly appropriate framework in which to study and intervene in such systems by treating neural elements (cells, volumes) as nodes in a graph and neural interactions (synapses, white matter tracts) as edges in that graph. Here, we review the emerging discipline of network neuroscience, which uses and develops tools from graph theory to better understand and manipulate neural systems from micro- to macroscales. We present examples of how human brain imaging data are being modeled with network analysis and underscore potential pitfalls. We then highlight current computational and theoretical frontiers and emphasize their utility in informing diagnosis and monitoring, brain–machine interfaces, and brain stimulation. A flexible and rapidly evolving enterprise, network neuroscience provides a set of powerful approaches and fundamental insights that are critical for the neuroengineer's tool kit.
CRISPR–Cas9 Structures and Mechanisms
Authors: Jiang Fuguo , Doudna Jennifer A.
Published: April 2017

Many bacterial clustered regularly interspaced short palindromic repeats (CRISPR)–CRISPR-associated (Cas) systems employ the dual RNA–guided DNA endonuclease Cas9 to defend against invading phages and conjugative plasmids by introducing site-specific double-stranded breaks in target DNA. Target recognition strictly requires the presence of a short protospacer adjacent motif (PAM) flanking the target site, and subsequent R-loop formation and strand scission are driven by complementary base pairing between the guide RNA and target DNA, Cas9–DNA interactions, and associated conformational changes. The use of CRISPR–Cas9 as an RNA-programmable DNA targeting and editing platform is simplified by a synthetic single-guide RNA (sgRNA) mimicking the natural dual trans-activating CRISPR RNA (tracrRNA)–CRISPR RNA (crRNA) structure. This review aims to provide an in-depth mechanistic and structural understanding of Cas9-mediated RNA-guided DNA targeting and cleavage. Molecular insights from biochemical and structural studies provide a framework for rational engineering aimed at altering catalytic function, guide RNA specificity, and PAM requirements and reducing off-target activity for the development of Cas9-based therapies against genetic diseases.
Single-Molecule Studies of Telomeres and Telomerase
Authors: Parks Joseph W. , Stone Michael D.
Published: April 2017

Telomeres are specialized chromatin structures that protect chromosome ends from dangerous processing events. In most tissues, telomeres shorten with each round of cell division, placing a finite limit on cell growth. In rapidly dividing cells, including the majority of human cancers, cells bypass this growth limit through telomerase-catalyzed maintenance of telomere length. The dynamic properties of telomeres and telomerase render them difficult to study using ensemble biochemical and structural techniques. This review describes single-molecule approaches to studying how individual components of telomeres and telomerase contribute to function. Single-molecule methods provide a window into the complex nature of telomeres and telomerase by permitting researchers to directly visualize and manipulate the individual protein, DNA, and RNA molecules required for telomere function. The work reviewed in this article highlights how single-molecule techniques have been utilized to investigate the function of telomeres and telomerase.
Rate Constants and Mechanisms of Protein–Ligand Binding
Authors: Pang Xiaodong , Zhou Huan-Xiang
Published: April 2017

Whereas protein–ligand binding affinities have long-established prominence, binding rate constants and binding mechanisms have gained increasing attention in recent years. Both new computational methods and new experimental techniques have been developed to characterize the latter properties. It is now realized that binding mechanisms, like binding rate constants, can and should be quantitatively determined. In this review, we summarize studies and synthesize ideas on several topics in the hope of providing a coherent picture of and physical insight into binding kinetics. The topics include microscopic formulation of the kinetic problem and its reduction to simple rate equations; computation of binding rate constants; quantitative determination of binding mechanisms; and elucidation of physical factors that control binding rate constants and mechanisms.
Structures of Large Protein Complexes Determined by Nuclear Magnetic Resonance Spectroscopy
Authors: Huang Chengdong , Kalodimos Charalampos G.
Published: April 2017

Nuclear magnetic resonance (NMR) spectroscopy has been instrumental during the past two decades in providing high-resolution structures of protein complexes. It has been the method of choice for determining the structure of dynamic protein complexes, which are typically recalcitrant to other structural techniques. Until recently, NMR spectroscopy has yielded structures of small or medium-sized protein complexes, up to approximately 30–40 kDa. Major breakthroughs during the past decade, especially in isotope-labeling techniques, have enabled NMR characterization of large protein systems with molecular weights of hundreds of kDa. This has provided unique insights into the binding, dynamic, and allosteric properties of large systems. Notably, there is now a slowly but steadily growing list of large, dynamic protein complexes whose atomic structure has been determined by NMR. Many of these complexes are characterized by a high degree of flexibility and, thus, their structures could not have been obtained using other structural methods. Especially in the field of molecular chaperones, NMR has recently provided the first-ever high-resolution structures of their complexes with unfolded proteins. Further technological advances will establish NMR as the primary tool for obtaining atomic structures of challenging systems with even higher complexity.
Long-Range Interactions in Riboswitch Control of Gene Expression
Authors: Jones Christopher P. , Ferré-D'Amaré Adrian R.
Published: April 2017

Riboswitches are widespread RNA motifs that regulate gene expression in response to fluctuating metabolite concentrations. Known primarily from bacteria, riboswitches couple specific ligand binding and changes in RNA structure to mRNA expression in cis. Crystal structures of the ligand binding domains of most of the phylogenetically widespread classes of riboswitches, each specific to a particular metabolite or ion, are now available. Thus, the bound states—one end point—have been thoroughly characterized, but the unbound states have been more elusive. Consequently, it is less clear how the unbound, sensing riboswitch refolds into the ligand binding–induced output state. The ligand recognition mechanisms of riboswitches are diverse, but we find that they share a common structural strategy in positioning their binding sites at the point of the RNA three-dimensional fold where the residues farthest from one another in sequence meet. We review how riboswitch folds adhere to this fundamental strategy and propose future research directions for understanding and harnessing their ability to specifically control gene expression.
Single-Molecule Analysis of Bacterial DNA Repair and Mutagenesis
Authors: Uphoff Stephan , Sherratt David J.
Published: April 2017

Ubiquitous conserved processes that repair DNA damage are essential for the maintenance and propagation of genomes over generations. Then again, inaccuracies in DNA transactions and failures to remove mutagenic lesions cause heritable genome changes. Building on decades of research using genetics and biochemistry, unprecedented quantitative insight into DNA repair mechanisms has come from the new-found ability to measure single proteins in vitro and inside individual living cells. This has brought together biologists, chemists, engineers, physicists, and mathematicians to solve long-standing questions about the way in which repair enzymes search for DNA lesions and form protein complexes that act in DNA repair pathways. Furthermore, unexpected discoveries have resulted from capabilities to resolve molecular heterogeneity and cell subpopulations, provoking new questions about the role of stochastic processes in DNA repair and mutagenesis. These studies are leading to new technologies that will find widespread use in basic research, biotechnology, and medicine.
Recent Developments and Challenges in Optimization-Based Process Synthesis
Authors: Chen Qi , Grossmann I.E.
Published: April 2017

This article first reviews recent developments in process synthesis and discusses some of the major challenges in the theory and practice in this area. Next, the article reviews key concepts in optimization-based conceptual design, namely superstructure representations, multilevel models, optimization methods, and modeling environments. A brief review of the synthesis of major subsystems and flowsheets is presented. Finally, the article closes with a critical assessment and future research challenges for the process synthesis area.
Trait Impulsivity and the Externalizing Spectrum
Authors: Beauchaine Theodore P. , Zisner Aimee R. , Sauder Colin L.
Published: April 2017

This article reviews evidence that trait impulsivity—expressed early in life as the hyperactive–impulsive and combined presentations of attention-deficit/hyperactivity disorder (ADHD)—is a bottom-up, subcortically mediated vulnerability to all externalizing disorders. This vulnerability arises from deficient mesolimbic dopamine responding, which imbues psychological states (irritability, discontentment) that motivate excessive approach behavior (hyperactivity, impulsivity). Through complex interactions with (a) aversive motivational states that arise from largely independent subcortical systems, (b) emotion regulatory mechanisms that arise from top-down, cortical modulation of subcortical neural function, and (c) environmental risk factors that shape and maintain emotion dysregulation, trait impulsivity confers vulnerability to increasingly severe externalizing behaviors across development. This perspective highlights the importance of identifying transdiagnostic neural vulnerabilities to psychopathology; dovetails with the hierarchical, latent structure of psychopathology; and suggests that progression along the externalizing spectrum is an ontogenic process whereby a common, multifactorially inherited trait interacts with endogenous and exogenous influences to yield increasingly intractable externalizing behaviors across development.
Schooling and Children's Mental Health: Realigning Resources to Reduce Disparities and Advance Public Health
Authors: Atkins Marc S. , Cappella Elise , Shernoff Elisa S. , Mehta Tara G. , Gustafson Erika L.
Published: April 2017

Schools have long been the primary setting for children's mental health services but have neither the resources nor the expertise to manage these services independently. The critical importance of school success for children's adjustment provides a strong rationale for schooling as an essential component of children's mental health services. In this article, we review evidence for how schooling and mental health coalesce, suggesting an alignment of school and community mental health resources that prioritizes successful schooling as a key mental health outcome. We describe collaborative principles and ecological practices that advance a public health focus on children's mental health while also reducing the burden on schools to maintain mental health services. We close with a model of mental health services illustrating these principles and practices in high-poverty urban schools and propose future directions for research and practice to promote positive mental health for all children and youth.
The Microbiome and Human Biology
Authors: Knight Rob , Callewaert Chris , Marotz Clarisse , Hyde Embriette R. , Debelius Justine W. , McDonald Daniel , Sogin Mitchell L.
Published: April 2017

Over the past few years, microbiome research has dramatically reshaped our understanding of human biology. New insights range from an enhanced understanding of how microbes mediate digestion and disease processes (e.g., in inflammatory bowel disease) to surprising associations with Parkinson's disease, autism, and depression. In this review, we describe how new generations of sequencing technology, analytical advances coupled to new software capabilities, and the integration of animal model data have led to these new discoveries. We also discuss the prospects for integrating studies of the microbiome, metabolome, and immune system, with the goal of elucidating mechanisms that govern their interactions. This systems-level understanding will change how we think about ourselves as organisms.
Active Crystal Growth Techniques for Quantum Materials
Authors: Schmehr Julian L. , Wilson Stephen D.
Published: April 2017

We review recent advances in crystal growth techniques, focusing on the development of novel quantum materials. Recent progress in instrumentation design, opening new avenues in bulk crystal growth of oxide and intermetallic compounds, is highlighted. Specifically, we illustrate leading techniques that allow for the active control of crystal nucleation/growth and provide platforms for the realization of single crystals with ultrahigh purity and minimized defects. Advances in the postgrowth manipulation of crystals, as well as the impact of purification techniques on the stabilization of delicate quantum phases, are also discussed. Throughout, we highlight new scientific avenues opened by access to high-purity single-crystal samples.
DNA-Driven Assembly: From Polyhedral Nanoparticles to Proteins
Authors: Girard Martin , Millan Jaime A. , Olvera de la Cruz Monica
Published: April 2017

Directed crystallization of a large variety of nanoparticles, including proteins, via DNA hybridization kinetics has led to unique materials with a broad range of crystal symmetries. The nanoparticles are functionalized with DNA chains that link neighboring functionalized units. The shape of the nanoparticle, the DNA length, the sequence of the hybridizing DNA linker, and the grafting density determine the crystal symmetries and lattice spacing. By carefully selecting these parameters, one can, in principle, achieve all the symmetries found for both atomic and colloidal crystals of asymmetric shapes as well as new symmetries and can drive transitions between them. A scale-accurate coarse-grained model with explicit DNA chains provides the design parameters, including the degree of hybridization, to achieve specific crystal structures. The model also provides surface energy values to determine the shape of defect-free single crystals with macroscopic anisotropic properties, which has potential for the fabrication of materials with specific optical and mechanical properties.
Zebrafish Behavior: Opportunities and Challenges
Authors: Orger Michael B. , de Polavieja Gonzalo G.
Published: April 2017

A great challenge in neuroscience is understanding how activity in the brain gives rise to behavior. The zebrafish is an ideal vertebrate model to address this challenge, thanks to the capacity, at the larval stage, for precise behavioral measurements, genetic manipulations, and recording and manipulation of neural activity noninvasively and at single-neuron resolution throughout the whole brain. These techniques are being further developed for application in freely moving animals and juvenile stages to study more complex behaviors including learning, decision making, and social interactions. We review some of the approaches that have been used to study the behavior of zebrafish and point to opportunities and challenges that lie ahead.
From 50 Years Ago, the Birth of Modern Liquid-State Science
Authors: Chandler David
Published: April 2017

The story told in this autobiographical perspective begins 50 years ago, at the 1967 Gordon Research Conference on the Physics and Chemistry of Liquids. It traces developments in liquid-state science from that time, including contributions from the author, and especially in the study of liquid water. It emphasizes the importance of fluctuations and the challenges of far-from-equilibrium phenomena.
Roaming: A Phase Space Perspective
Authors: Mauguière Frédéric A.L. , Collins Peter , Kramer Zeb C. , Carpenter Barry K. , Ezra Gregory S. , Farantos Stavros C. , Wiggins Stephen
Published: April 2017

In this review we discuss the recently described roaming mechanism for chemical reactions from the point of view of nonlinear dynamical systems in phase space. The recognition of the roaming phenomenon shows the need for further developments in our fundamental understanding of basic reaction dynamics, as is made clear by considering some questions that cut across most studies of roaming: Is the dynamics statistical? Can transition state theory be applied to estimate roaming reaction rates? What role do saddle points on the potential energy surface play in explaining the behavior of roaming trajectories? How do we construct a dividing surface that is appropriate for describing the transformation from reactants to products for roaming trajectories? How should we define the roaming region? We show that the phase space perspective on reaction dynamics provides the setting in which these questions can be properly framed and answered. We illustrate these ideas by considering photodissociation of formaldehyde. The phase-space formulation allows an unambiguous description of all possible reactive events, which also allows us to uncover the phase space mechanism that explains which trajectories roam, as opposed to evolving toward a different reactive event.
The Hydrated Electron
Authors: Herbert John M. , Coons Marc P.
Published: April 2017

Existence of a hydrated electron as a byproduct of water radiolysis was established more than 50 years ago, yet this species continues to attract significant attention due to its role in radiation chemistry, including DNA damage, and because questions persist regarding its detailed structure. This work provides an overview of what is known in regards to the structure and spectroscopy of the hydrated electron, both in liquid water and in clusters [Formula: see text], the latter of which provide model systems for how water networks accommodate an excess electron. In clusters, the existence of both surface-bound and internally bound states of the excess electron has elicited much debate, whereas in bulk water there are questions regarding how best to understand the structure of the excess electron's spin density. The energetics of the equilibrium species e−(aq) and its excited states, in bulk water and at the air/water interface, are also addressed.
Transitioning Toward Nutrition-Sensitive Food Systems in Developing Countries
Authors: Pingali Prabhu , Sunder Naveen
Published: April 2017

A nutrition-sensitive food system is one that goes beyond staple grain productivity and places emphasis on the consumption of micronutrient-rich nonstaples through a variety of market and nonmarket interventions. A nutrition-sensitive approach not only considers policies related to macrolevel availability and access to nutritious food, but it also focuses on household- and individual-level determinants of improved nutrition. In addition to agriculture, intrahousehold equity, behavior change, food safety, and access to clean water and sanitation are integral components of the food system. This article provides a detailed review, from an economic perspective, on the multisectoral pathways through which agriculture influences nutrition. A critical challenge is to identify and implement food and nutrition policies that are appropriate to the particular stage of structural transformation in the country of concern.
Effect of an educational game on university students’ learning about action potentials
Authors: Luchi Kelly Cristina Gaviao , Montrezor Luís Henrique , Marcondes Fernanda K.
Published: April 2017

The aim of this study was to evaluate the effect of an educational game that is used for teaching the mechanisms of the action potentials in cell membranes. The game was composed of pieces representing the intracellular and extracellular environments, ions, ion channels, and the Na+-K+-ATPase pump. During the game activity, the students arranged the pieces to demonstrate how the ions move through the membrane in a resting state and during an action potential, linking the ion movement with a graph of the action potential. To test the effect of the game activity on student understanding, first-year dental students were given the game to play at different times in a series of classes teaching resting membrane potential and action potentials. In all experiments, students who played the game performed better in assessments. According to 98% of the students, the game supported the learning process. The data confirm the students’ perception, indicating that the educational game improved their understanding about action potentials.
Monitoring undergraduate student needs and activities at Experimental Biology: APS pilot survey
Authors: Nichols Nicole L. , Ilatovskaya Daria V. , Matyas Marsha L.
Published: April 2017

Life science professional societies play important roles for undergraduates in their fields and increasingly offer membership, fellowships, and awards for undergraduate students. However, the overall impacts of society-student interactions have not been well studied. Here, we sought to develop and test a pilot survey of undergraduate students to determine how they got involved in research and in presenting at the Experimental Biology (EB) meeting, what they gained from the scientific and career development sessions at the meeting, and how the American Physiological Society (APS) can best support and engage undergraduate students. This survey was administered in 2014 and 2015 to undergraduate students who submitted physiology abstracts for and attended EB. More than 150 students responded (38% response rate). Respondents were demographically representative of undergraduate students majoring in life sciences in the United States. Most students (72%) became involved in research through a summer research program or college course. They attended a variety of EB sessions, including poster sessions and symposia, and found them useful. Undergraduate students interacted with established researchers at multiple venues. Students recommended that APS provide more research fellowships (25%) and keep in touch with students via both e-mail (46%) and social media (37%). Our results indicate that APS’ EB undergraduate activities are valued by students and are effective in helping them have a positive scientific meeting experience. These results also guided the development of a more streamlined survey for use in future years.
Memetic Differential Evolution with an Improved Contraction Criterion
Authors: Peng Lei , Zhang Yanyun , Dai Guangming , Wang Maocai
Published: April 2017

Memetic algorithms with an appropriate trade-off between the exploration and exploitation can obtain very good results in continuous optimization. In this paper, we present an improved memetic differential evolution algorithm for solving global optimization problems. The proposed approach, called memetic DE (MDE), hybridizes differential evolution (DE) with a local search (LS) operator and periodic reinitialization to balance the exploration and exploitation. A new contraction criterion, which is based on the improved maximum distance in objective space, is proposed to decide when the local search starts. The proposed algorithm is compared with six well-known evolutionary algorithms on twenty-one benchmark functions, and the experimental results are analyzed with two kinds of nonparametric statistical tests. Moreover, sensitivity analyses for parameters in MDE are also made. Experimental results have demonstrated the competitive performance of the proposed method with respect to the six compared algorithms.
Care-Related and Maternal Risk Factors Associated with the Antenatal Nondetection of Intrauterine Growth Restriction: A Case-Control Study from Bremen, Germany
Authors: Ernst Sinja Alexandra , Brand Tilman , Reeske Anna , Spallek Jacob , Petersen Knud , Zeeb Hajo
Published: April 2017

Objective. To identify care-related and maternal risk factors for the antenatal nondetection of IUGR.Methods. In this hospital-based case-control study we compared antenatally undetected IUGR neonates (cases) to detected IUGR neonates (controls). Data were collected using newborn documentation sheets and standardized personal interviews with the mothers. We calculated antenatal detection rates and used uni- and multivariable logistic regression models to assess the association of antenatal nondetection of IUGR and maternal and care-related factors.Results. A total of 161 neonates from three hospitals were included in the study. Suboptimal fetal growth was identified antenatally inn=77pregnancies while inn=84it was not detected antenatally (antenatal detection rate: 47.8%). Severity of IUGR, maternal complications, and a Doppler examination during the course of pregnancy were associated with IUGR detection. We did not find statistically significant differences regarding parental socioeconomic status and maternal migration background.Conclusions. In our study, about half of all pregnancies affected by suboptimal growth remained undetected. Future in-depth studies with larger study populations should further examine factors that could increase antenatal detection rates for IUGR.
OCT4B1 Regulates the Cellular Stress Response of Human Dental Pulp Cells with Inflammation
Authors: Liu Lu , Huang Rong , Yang Ruiqi , Wei Xi
Published: April 2017

Introduction. Infection and apoptosis are combined triggers for inflammation in dental tissues. Octamer-binding transcription factor 4-B1 (OCT4B1), a novel spliced variant of OCT4 family, could respond to the cellular stress and possess antiapoptotic property. However, its specific role in dental pulpitis remains unknown. Methods. To investigate the effect of OCT4B1 on inflammation of dental pulp cells (DPCs), its expression in inflamed dental pulp tissues and DPCs was examined by in situ hybridization, real-time PCR, and FISH assay. OCT4B1 overexpressed DPCs model was established, confirmed by western blot and immunofluorescence staining, and then stimulated with Lipopolysaccharide (LPS). Apoptotic rate was determined by Hoechst/PI staining and FACS. Cell survival rate was calculated by CCK8 assay. Results. In situ hybridization, real-time PCR, and FISH assay revealed that OCT4B1 was extensively expressed in inflamed dental pulp tissues and DPCs with LPS stimulation. Western blot and immunofluorescence staining showed the expression of OCT4B1 and OCT4B increased after OCT4B1 transfection. Hoechst/PI staining and FACS demonstrated that less red/blue fluorescence was detected and apoptotic percentage decreased (3.45%) after transfection. CCK8 demonstrated that the survival rate of pCDH-OCT4B1-flag cells increased. Conclusions. OCT4B1 plays an essential role in inflammation and apoptosis of DPCs. OCT4B might operate synergistically with OCT4B1 to reduce apoptosis.
Screening of Tumor Suppressor Genes in Metastatic Colorectal Cancer
Authors: Qi Lu , Ding Yanqing
Published: April 2017

Most tumor suppressor genes are commonly inactivated in the development of colorectal cancer (CRC). The activation of tumor suppressor genes may be beneficial to suppress the development and metastasis of CRC. This study analyzed genes expression and methylation levels in different stages of CRC. Genes with downregulated mRNA expression and upregulated methylation level in advanced CRC were screened as the potential tumor suppressor genes. After comparing the methylation level of screened genes, we found that MBD1 gene had downregulated mRNA expression and upregulated methylation levels in advanced CRC and continuously upregulated methylation level in the progression of CRC. Enrichment analysis revealed that genes expression in accordance with the elevated expression of MBD1 mainly located on chromosomes 17p13 and 17p12 and 8 tumor suppressor genes located on chromosome 17p13. Further enrichment analysis of transcription factor binding site identified that SP1 binding site had higher enrichment and could bind with MBD1. In conclusion, MBD1 may be a tumor suppressor gene in advanced CRC and affect the development and metastasis of CRC by regulating 8 tumor suppressor genes through binding with SP1.
Nonlinear Mechanooptical Transmittance Controlled by a Rotating TiO2 Thin Solid Film with Embedded Bimetallic Au-Pt Nanoparticles
Authors: Piña-Díaz A. J. , Trejo-Valdez M. , Morales-Bonilla S. , Torres-San Miguel C. R. , Martínez-González C. L. , Torres-Torres C.
Published: April 2017

The modification in the third-order nonlinear optical behavior exhibited by a titanium dioxide thin solid film with embedded Gold-Platinum nanoparticles was induced by nanosecond optical pulses. A Nd:YAG laser system was employed for the experiments explored by a vectorial two-wave mixing method with the sample in rotation. The nanostructures were prepared by a sol-gel technique. Transmission Electron Microscopy studies and ultraviolet-optical spectroscopy measurements were undertaken. The evolution of the optical transmittance exhibited by the sample in rotation controlled by a servomechanism was observed. Potential applications for developing mechanooptical functions based on third-order optical nonlinearities were contemplated.
Impacts of Absorber Loadings on Simulating the Multipath Channel in a Reverberation Chamber
Authors: Zhou Xin , Zhong Zhangdui , Bian Xin , He Ruisi , Guan Ke , Sun Ruoyu , Liu Ke , Guo Xiaotao
Published: April 2017

In reverberation chambers, the multipath channels with different delay characteristics can be generated by loading the chamber with different amounts of absorbers. This paper investigates the impacts of absorber loadings on the delay characteristics based on realistic measurements. An efficient method for estimating the root-mean-square (rms) delay spread in the chamber is presented. Furthermore, it is found that the chamber loadings also significantly affect the quality of a digitally modulated signal and the corresponding modulation quality measurements are performed.
Optical Channel Capacity Upgrade Based on Multiwavelength Conversion XGM Using Semiconductor Optical Amplifier for Access Networks
Authors: Ab-rahman Mohammad Syuhaimi , Swedan Abdul Hameed Almabrok
Published: April 2017

This paper demonstrates a 10 Gb/s one-to-two-wavelength conversion configuration based on cross-gain modulation for optical access networks using a single TW-SOA. The method is capable of converting a signal data of specific wavelength 1541 nm to certain wavelengths of CW’s laser 1554 nm and 1558 nm with 4 nm spacing. The pump power level was classified due to channel response. A result obtained was the best power level offering wavelength converter between −6 and 3 dBm. The conversion efficiency achievement provided an acceptable result for probe signals. The findings ofQ-factor performance were investigated. TheQvalues were found to be more than 9 for point to point transmission and 20 km fiber configurations for the original and converted signal. The technique implemented at 20 km and the power of all channels were adequate to provide a splitting ratio of 1/64 for the launched pump power 3 dBm.
Severe Murine Typhus Presenting with Acalculous Cholecystitis: A Case Report and Literature Review
Authors: Spernovasilis Nikolaos , Tsioutis Constantinos , Zafeiri Maria , Hamilos Georgios , Gikas Achilleas
Published: April 2017

A 54-year-old otherwise healthy male, who was being evaluated for prolonged fever, developed clinical and ultrasonographic signs compatible with acute acalculous cholecystitis. Diagnosis of murine typhus was confirmed by serology and the patient was treated with doxycycline. He improved rapidly and all clinical and laboratory abnormalities returned to normal. The present case dictates that knowledge of the local epidemiology and keeping a high index of clinical suspicion can help recognize uncommon manifestations of murine typhus, in order to treat appropriately and avoid unnecessary investigations and interventions.
Representing Glaciations and Subglacial Processes in Hydrogeological Models: A Numerical Investigation
Authors: Sterckx Arnaud , Lemieux Jean-Michel , Vaikmäe Rein
Published: April 2017

The specific impact of glacial processes on groundwater flow and solute transport under ice-sheets was determined by means of numerical simulations. Groundwater flow and the transport of δ18O, TDS, and groundwater age were simulated in a generic sedimentary basin during a single glacial event followed by a postglacial period. Results show that simulating subglacial recharge with a fixed flux boundary condition is relevant only for small fluxes, which could be the case under partially wet-based ice-sheets. Glacial loading decreases overpressures, which appear only in thick and low hydraulic diffusivity layers. If subglacial recharge is low, glacial loading can lead to underpressures after the retreat of the ice-sheet. Isostasy reduces considerably the infiltration of meltwater and the groundwater flow rates. Below permafrost, groundwater flow is reduced under the ice-sheet but is enhanced beyond the ice-sheet front. Accounting for salinity-dependent density reduces the infiltration of meltwater at depth. This study shows that each glacial process is potentially relevant in models of subglacial groundwater flow and solute transport. It provides a good basis for building and interpreting such models in the future.
Global Attractors of the Extensible Plate Equations with Nonlinear Damping and Memory
Authors: Yao Xiaobin , Ma Qiaozhen
Published: April 2017

We prove in this paper the existence of a global attractor for the plate equations of Kirchhoff type with nonlinear damping and memory using the contraction function method.
Stemness in Cancer: Stem Cells, Cancer Stem Cells, and Their Microenvironment
Authors: Aponte Pedro M. , Caicedo Andrés
Published: April 2017

Stemness combines the ability of a cell to perpetuate its lineage, to give rise to differentiated cells, and to interact with its environment to maintain a balance between quiescence, proliferation, and regeneration. While adult Stem Cells display these properties when participating in tissue homeostasis, Cancer Stem Cells (CSCs) behave as their malignant equivalents. CSCs display stemness in various circumstances, including the sustaining of cancer progression, and the interaction with their environment in search for key survival factors. As a result, CSCs can recurrently persist after therapy. In order to understand how the concept of stemness applies to cancer, this review will explore properties shared between normal and malignant Stem Cells. First, we provide an overview of properties of normal adult Stem Cells. We thereafter elaborate on how these features operate in CSCs. We then review the organization of microenvironment components, which enables CSCs hosting. We subsequently discuss Mesenchymal Stem/Stromal Cells (MSCs), which, although their stemness properties are limited, represent essential components of the Stem Cell niche and tumor microenvironment. We next provide insights of the therapeutic strategies targeting Stem Cell properties in tumors and the use of state-of-the-art techniques in future research. Increasing our knowledge of the CSCs microenvironment is key to identifying new therapeutic solutions.
Benefits of Levothyroxine Replacement Therapy on Nonalcoholic Fatty Liver Disease in Subclinical Hypothyroidism Patients
Authors: Liu Lu , Yu Yong , Zhao Meng , Zheng Dongmei , Zhang Xu , Guan Qingbo , Xu Chao , Gao Ling , Zhao Jiajun , Zhang Haiqing
Published: April 2017

Objectives. To evaluate the effect of levothyroxine (LT4) replacement therapy on nonalcoholic fatty liver disease (NAFLD) in subclinical hypothyroidism (SCH) patients.Methods. This study was a post hoc analysis of a randomized controlled trial and involved 33 significant and 330 mild SCH patients. All of the significant SCH patients received LT4supplement. The mild SCH patients were grouped as LT4treated or not. After 15 months of follow-up, prevalence of NAFLD in each group was reevaluated. Subgroup analysis was conducted in mild SCH patients with dyslipidemia.Results. After treatment with LT4, the prevalence of NAFLD in significant SCH patients reduced from 48.5% to 24.2% (p=0.041). In mild SCH patients, prevalence of NAFLD and serum alanine aminotransferase (ALT) was not significantly affected by LT4supplementation. Nonetheless, mild SCH patients with dyslipidemia who received LT4treatment experienced decreases in the prevalence of NAFLD and serum ALT levels (p<0.05for both). In contrast, these parameters remained comparably stable in patients who were not treated.Conclusion. LT4supplementation has benefits on NAFLD in significant SCH patients or mild SCH patients with dyslipidemia. For NAFLD patients with SCH, appropriate supplementation of LT4may be an effective means of controlling NAFLD. The original trial was registered with ClinicalTrials.gov (NCT01848171).
Endoscopic Ultrasound-Guided Biliary Drainage Using Self-Expandable Metal Stent for Malignant Biliary Obstruction
Authors: Lu Lei , Tang Xiaowei , Jin Hangbin , Yang Jianfeng , Zhang Xiaofeng
Published: April 2017

Purpose. Endoscopic ultrasound-guided biliary drainage (EUS-BD) has been increasingly reported worldwide. However, studies concerning EUS-BD from Mainland China are sporadic. This study aims to investigate the feasibility, efficacy, and safety of EUS-BD using SEMS in a single center from Mainland China. Methods. Between November 2011 and August 2015, 24 patients underwent EUS-BD using a standardized algorithm. Results. Three patients underwent rendezvous technique (RV), 4 underwent hepaticogastrostomy (HGS), and 17 underwent choledochoduodenostomy (CDS). The technical and clinical success rates were 95.8% (23/24) and 100% (23/23), respectively. Mean procedure time for the CDS group (35.9 ± 5.0 min) or HGS group (39.3 ± 5.0 min) was significantly shorter than that for the RV group (64.7 ± 9.1 min) (P<0.05). Complications (13%) included (1) cholangitis and (2) postprocedure hemorrhage. During the follow-up periods (mean 6.4 months), 22 (91.7%) patients died of tumor progression with mean stent patency of 5.8 ± 2.2 months. Stent occlusion occurred in 2 (8.7%) patients. Conclusion. EUS-BD using SEMS is a feasible, effective, and safe alternative for biliary decompression after failed ERCP. EUS-RV may not be the first-line choice for EUS-BD in a medium volume center. Further evaluation and experience of this method are needed.
A Qualitative Inquiry into Nursing Students’ Experience of Facilitating Reflection in Clinical Setting
Authors: Karimi Shahnaz , Haghani Fariba , Yamani Nikoo , Najafi Kalyani Majid
Published: April 2017

Background and Aim. Reflection is known as a skill that is central to nursing students’ professional development. Due to the importance and the role of reflection in clinical areas of nursing, it is important to know how to achieve it. However, nursing trainers face the challenge of how to help their students to improve reflection in clinical settings. The aim of this study was to investigate the nursing students’ experiences of facilitating reflection during clinical practice. This qualitative study was conducted by qualitative content analysis approach. Twenty nursing students during the second to eighth semester of their educational program were selected for participation using purposive sampling. Data were collected through in-depth semistructured interviews. The interview was transcribed verbatim, and qualitative content analysis was used to analyze the data. From the data analysis, four main themes were extracted. Motivation to reflect, complex experiences, efficient trainer, and effective relations were four main themes obtained from study that, in interaction with each other, had facilitating roles in students’ reflective process on experiences. The findings revealed that the nursing students’ reflection in clinical settings is effective in personal and professional level. Reflection of nursing students depends on motivational and educational factors and these factors increase the quality of care in patients. Furthermore, nursing educators need to create nurturing climate as well as supporting reflective behaviors of nursing students.