bluuebunny/crossref_metadata_2025 huggingface dataset:
Midventricular Hypertrophic Obstructive Cardiomyopathy with Left Ventricular Aneurysm and Clot: The Role of Transesophageal Echocardiogram in Assessment and Management of Myomectomy
Authors: Kumar Bhupesh , Thingam Shyam KS , Negi Sunder Lal
Published: November 2014

Hypertrophic obstructive cardiomyopathy (HOCM) with mid ventricular obstruction leading to apical aneurysm and clot is very rare. Intraoperative transesophageal echocardiogram (TEE) can be used to know the maximum thickness of the septum, its distance from the aortic annulus and the apical extent of septal bulge. Postresection TEE can provide information about residual obstruction or any complications. We present a case of 65-year-old male patient who underwent CABG, septal myectomy, Dor's procedure for aneurysm and clot removal. Septal resection was done under TEE guidance.

How to cite this article

Dutta V, Raj R, Kumar B, Bahl A, Thingam SKS, Negi SL, Puri GD. Midventricular Hypertrophic Obstructive Cardiomyopathy with Left Ventricular Aneurysm and Clot: The Role of Transesophageal Echocardiogram in Assessment and Management of Myomectomy. J Perioper Echocardiogr 2014;2(2):58-60.
Pulmonary Artery-Pulmonary Vein Fistula: Contrast Echocardiography using Agitated Saline for Indirect Evaluation of Adequacy of Surgical Repair
Authors: Kiran Usha , Choudhury Minati , Narula Jitin , Chowdhary Ujjwal Kumar
Published: November 2014

Direct right pulmonary artery-left atrial communications are rare causes of congenital cyanotic heart disease. Bypassing of the pulmonary circulation and the filtering function of the lung predisposes these patients to high risk of stroke or cerebral embolism. Contrast echocardiography using transesophageal echocardiography helps in detection and/or confirmation of diagnosis of these extracardiac shunts as two-dimensional echocardiography of the heart is essentially normal in such patients. Additionally, it can help in the assessment of adequacy of surgical repair in the postoperative period.

How to cite this article

Narula J, Choudhury M, Chowdhary UK, Kiran U. Pulmonary Artery-Pulmonary Vein Fistula: Contrast Echocardiography using Agitated Saline for Indirect Evaluation of Adequacy of Surgical Repair. J Perioper Echocardiogr 2014;2(2):61-64.
Heterotrophic prokaryote distribution along a 2300 km transect in the North Pacific subtropical gyre during strong La Niña conditions: relationship between distribution and hydrological conditions
Authors: Girault M. , Arakawa H. , Barani A. , Ceccaldi H. J. , Hashihama F. , Gregori G.
Published: November 2014

Abstract. The spatial distribution of heterotrophic prokaryotes was investigated during the Tokyo–Palau cruise in the western part of the North Pacific subtropical gyre (NPSG) along a north–south transect between 33.60 and 13.25° N. The cruise was conducted in three different hydrological areas identified as the Kuroshio region, the Subtropical gyre area and the Transition zone. Two eddies were crossed along the transect: one cold core cyclonic eddy and one warm core anticyclonic eddy and distributions of the heterotrophic prokaryotes were recorded. By using analytical flow cytometry and a nucleic acid staining protocol, heterotrophic prokaryotes were discriminated into three subgroups depending on their nucleic acid content (low, high and very high nucleic acid contents labeled LNA, HNA and VHNA, respectively). Statistical analyses performed on the dataset showed that LNA, mainly associated with temperature and salinity, were dominant in all the hydrological regions. In contrast, HNA distribution seemed to be associated with temperature, salinity, Chl a and silicic acid. A latitudinal increase in the HNA / LNA ratio was observed along the north–south transect and was related to higher phosphate and nitrate concentrations. In the Kuroshio Current, it is suggested that the high concentration of heterotrophic prokaryotes observed at station 4 was linked to the path of the cold cyclonic eddy core. In contrast, it is thought that low concentrations of heterotrophic prokaryotes in the warm core of the anticyclonic gyre (Sta. 9) are related to the low nutrient concentrations measured in the seawater column. Our results showed that the high variability between the various heterotrophic prokaryote cluster abundances depend both on the mesoscale structures and the oligotrophic gradient.
Learning through Osmosis: A collaborative platform for medical education
Authors: Haynes M. Ryan , Gaglani Shiv M. , Wilcox Mark V. , Mitchell Terence , DeLeon Valerie , Goldberg Harry
Published: November 2014

Formative assessment has been shown to improve medical student performance and retention, but many learners lack access to formative assessments because faculty members have limited time to create such resources, and acquiring existing commercial review banks is expensive. In response, we developed a collaborative learning platform for medical student self-assessment called Osmosis (http://osmosis.org/). Osmosis is a web- and mobile-learning platform that provides free access to thousands of crowd-sourced, high-yield practice questions and explanations. The quality of these questions and resources is enhanced through a unique social rating and commenting feature.

During the first year Osmosis was launched at the Johns Hopkins School of Medicine in January 2012, approximately 250 students in the first and second year classes spent over 2,400 hours answering more than 5,000 questions close to half-a-million times (∼2,000 questions answered/student). In addition, over 1,000 Creative Commons-licensed images and YouTube videos have been shared. Usage data and reception by students indicate that the platform fits well into busy schedules and that participants value its role in promoting collaboration and self-assessing knowledge gaps.

We are currently developing additional features for the Osmosis platform related to knowledge retention and curricular design. Since the vast majority of questions and resources on Osmosis are shared under non-restrictive licenses, such as Creative Commons, we are making Osmosis available to peer institutions. It is our hope that more students and faculty members will benefit from, and contribute to, the Osmosis library.
Engaging a global community of learners and practitioners in the care of the critically ill child
Authors: Burns Jeffrey , O'Brien Sarah , Burns Rebecca
Published: November 2014

The traditional methods of education, while once revolutionary, are failing to keep pace in the twenty-first century. OPENPediatrics™ has created an interactive, virtual training and knowledge exchange platform to enhance the quality of pediatric critical care. It has the potential to revolutionize the post-graduate medical education model. Designed by experienced physicians at Boston Children's Hospital, in collaboration with IBM Interactive, it offers asynchronous interactive learning and various avenues for knowledge sharing outside the walls of individual institutions. It is creating a digital, global community, based on adult learning principles, provided at no cost to the user.
A dialógica da performance e da Pedagogia
Authors: Sabatini Arthur J.
Published: November 2014

http://dx.doi.org/10.5902/1984644414779O presente texto discorre sobre a relação entre performance e pedagogia, buscando compreender a pedagogia como um gênero específico de performance. Isso posto, o trabalho procura responder as seguintes questões: que tipologia de discursos opera em situações pedagógicas? Qual é a relação entre o estudante e o professor? Quem ensina? Que tipos de conhecimento e formas de interpretação existem e estão sendo criados no contexto do ensino dos estudos da performance (histórica e sócio-ideologicamente)? Os conceitos e o léxico de Bakhtin constituem, por sua vez, mais que ferramentas metodológicas para a compreensão do ensino como performance; eles são, por assim dizer, a substância e o estilo de uma determinada forma de praticar e pensar o ensino.
Élaboration et validation de l’Échelle de motivation à bien réussir un test (ÉMRT)
Authors: Ndinga Pascal , Frenette Eric
Published: November 2014

La présente recherche concerne l’élaboration et la validation d’une Échelle de motivation à bien réussir un test (ÉMRT). Cette dernière est composée de quatre sous-échelles : motivation intrinsèque, motivation extrinsèque autodéterminée, motivation extrinsèque non autodéterminée et amotivation. Après le processus d’élaboration, la structure factorielle de l’ÉMRT a été testée lors de deux enjeux liés à l’évaluation (formatif et sommatif) aux fins de validation. Les résultats indiquent que l’ÉMRT respecte la structure factorielle à quatre sous-échelles et possède de bonnes qualités psychométriques. Enfin, des différences sont observées sur le plan des corrélations entre les sous-échelles de l’ÉMRT et la performance à un test en fonction de l’enjeu du test.
L’évaluation en classe en Suisse romande
Authors: Giroud Patricia Gilliéron , Tessaro Walther
Published: November 2014

La Suisse romande a connu récemment une période d’intenses réformes scolaires. De nombreuses études et recherches avaient alimenté les réflexions et suscité un fort intérêt pour une mise en application des innovations dans les classes. Malgré l’enthousiasme de départ, les réformes se sont heurtées à des oppositions inattendues. Politiques, parents et enseignants ont manifesté des doutes et des critiques, souvent virulents, contre les changements entrepris. L’abandon des notes chiffrées, épiphénomène des projets de réforme, occupera sans partage le devant de la scène politique et médiatique et entraînera un retour à des pratiques plus traditionnelles. Le bilan proposé dans cet article décrit les intentions des mouvements de réforme, les différentes phases de leur mise en oeuvre et les effets connus sur les pratiques enseignantes. Il met en évidence la complexité de nos systèmes scolaires et ses contradictions, tout en relevant les apports positifs d’une période d’échanges et d’actions en vue d’améliorer l’école.
L’évaluation des élèves en France, à un moment charnière de leur histoire?
Authors: Bardi Anne-Marie , Mégard Marie
Published: November 2014

L’éducation nationale française est fortement centralisée : programmes, horaires et sujets d’examen nationaux, autonomie des établissements quasi nulle jusqu’à aujourd’hui. Cette égalité d’objectifs et de moyens est supposée garantir une égalité de résultats ; ainsi, les établissements ne font pas l’objet d’évaluations, et les acquis des élèves n’étaient, jusqu’à une date récente, mesurés de façon systématique qu’à leur entrée dans chaque cycle, à des fins diagnostiques. Dans les classes de collège et de lycée, la note chiffrée synthétique est encore le seul mode d’expression de l’évaluation des élèves ; à l’école primaire, les livrets de compétences mis en place demeurent peu informatifs. Depuis 2005 cependant, de grand textes de cadrage engagent l’école française sur la voie d’une autre culture de l’évaluation : une loi de finance impose au ministère de l’Éducation nationale de rendre annuellement compte des acquis des élèves ; la loi dite « pour l’avenir de l’école » impose à la scolarité obligatoire qu’elle garantisse à chaque élève les moyens nécessaires à l’acquisition d’un socle commun de connaissances et de compétences ; enfin, un cadre européen édicte des objectifs en termes de compétences clés, notamment en langues vivantes. Les conditions d’une évolution des pratiques d’évaluation sont donc réunies, la question reste de savoir si l’école française saura se saisir de cette occasion.
Catégorisation de techniques de rétroaction pour l’enseignement universitaire
Authors: Bachy Sylviane , Lebrun Marcel
Published: November 2014

Cet article présente une catégorisation de techniques de rétroaction située par rapport au triangle didactique. Peu utilisées ou peu explicites, les techniques de rétroaction sont pourtant des leviers pour favoriser l’apprentissage des étudiants dans le contexte universitaire. En effet, elles soutiennent les régulations dans les interactions entre les apprenants, l’enseignant et le savoir. La catégorisation proposée répond à quatre questions : qui sont-ils, que savent-ils, comment apprennent-ils et qu’ont-ils appris. À partir de ces quatre questions simples, l’enseignant peut construire son dispositif et proposer des situations d’enseignement favorisant l’apprentissage des étudiants en milieu universitaire. Cette grille de lecture originale comme support à l’évaluation formative répond à des préoccupations actuelles des enseignants confrontés à l’effet de massification notamment pour le premier cycle universitaire.
Utilisation d’une version informatisée de la didactique de précision auprès d’élèves ayant un trouble envahissant du développement
Authors: Schuessler Katrine , Forget Jacques
Published: November 2014

La didactique de précision (DP) est un outil intéressant pour les intervenants oeuvrant auprès de personnes ayant un trouble envahissant du développement (TED). Ayant fait ses preuves, elle permet une visualisation directe et atomisée de l’évolution de l’apprentissage d’une personne et une mise à jour continue des interventions. L’objectif de l’étude est d’évaluer une version informatisée de la DP auprès d’élèves TED. L’étude, basée sur un devis quasi expérimental, est supportée par un modèle de recherche intrasujet, combiné à des niveaux de base multiples. Les résultats indiquent que l’utilisation d’une telle version a un effet significatif sur 56 % des interventions.
Ecosystem respiration increases with biofilm growth and bed forms: Flume measurements with resazurin
Authors: Haggerty Roy , Ribot Miquel , Singer Gabriel A. , Martí Eugènia , Argerich Alba , Agell Gemma , Battin Tom J.
Published: November 2014

In a set of streamside mesocosms, stream ecosystem respiration (ER) increased with biofilm biomass and flow heterogeneity (turbulence) generated by impermeable bed forms, even though those bed forms had no hyporheic exchange. Two streamside flumes with gravel beds (single layer of gravel) were operated in parallel. The first flume had no bed forms, and the second flume had 10 cm high dune‐shaped bed forms with a wavelength of 1.0 m. Ecosystem respiration was measured via resazurin reduction to resorufin in each flume at three different biomass stages during biofilm growth. Results support the hypothesis thatERincreases with flow heterogeneity generated by bed forms across all biofilm biomass stages. For the same biofilm biomass,ERwas up to 1.9 times larger for a flume with 10 cm high impermeable bed forms than for a flume without the bed forms. Further, the amount of increase inERassociated with impermeable bed forms was itself increased as biofilms grew. Regardless of bed forms, biofilms increased transient storage by a factor of approximately 4.
Changes in the stress field after the 2008 M7.2 Iwate‐Miyagi Nairiku earthquake in northeastern Japan
Authors: Yoshida Keisuke , Hasegawa Akira , Okada Tomomi , Iinuma Takeshi
Published: November 2014

In order to investigate changes in the stress field following the 2008 M7.2 Iwate‐Miyagi Nairiku earthquake in NE Japan, we determined many focal mechanisms within the focal area, using data from both the dense aftershock observation network deployed just after the main shock and other temporary and routinely operated stations in the surrounding area. Applying stress tensor inversions to these focal mechanism data, we estimated the detailed spatial distribution of the principal stress orientations in this event's source area. Estimated orientations of the maximum principal stress (σ1) axes differ significantly before and after the main shock. Before the main shock, the σ1 axis is oriented WNW‐ESE across the entire studied area, which is parallel to the plate convergence direction. After the main shock, however, the orientation of the σ1 axis changed significantly and showed remarkable spatial variation. In the northern and southern parts of the aftershock area, located relatively far from the main shock large slip area, the σ1 axes are oriented WNW‐ESE, similar to those before the main shock. In contrast, to the east and west of the central part of the aftershock area, the σ1 axes are oriented N‐S and NE‐SW, respectively. This characteristic spatial pattern of σ1 axis orientations is approximately consistent with that of static stress change associated with the main shock rupture, which strongly suggests that the spatially heterogeneous stress after the main shock is caused by such static stress change. The differential stress magnitude before the main shock is estimated to be less than 10–30 MPa, suggesting that the main shock faults are weak.
Improving stratospheric transport trend analysis based on SF6 and CO2 measurements
Authors: Ray Eric A. , Moore Fred L. , Rosenlof Karen H. , Davis Sean M. , Sweeney Colm , Tans Pieter , Wang Tao , Elkins James W. , Bönisch Harald , Engel Andreas , Sugawara Satoshi , Nakazawa T. , Aoki S.
Published: November 2014

In this study we reexamine nearly four decades of in situ balloon‐based stratospheric observations of SF6 and CO2 with an idealized model and reanalysis products. We use new techniques to account for the spatial and temporal inhomogeneity of the sparse balloon profiles and to calculate stratospheric mean ages of air more consistently from the observations with the idealized model. By doing so we are able to more clearly show and account for the variability of mean age of air throughout the bulk of the depth of the stratosphere. From an idealized model guided by the observations, we identify variability in the mean age due to the seasonal cycle of stratospheric transport, the quasi‐biennial oscillation in tropical zonal winds, major volcanic eruptions, and linear trends that vary significantly with altitude. We calculate a negative mean age trend in the lowest 5 km of the stratosphere that agrees within uncertainties with a trend calculated from a set of chemistry climate model mean ages in this layer. The mean age trends reverse sign in the middle and upper stratosphere and are in agreement with a previous positive trend estimate using the same observational data set, although we have substantially reduced the uncertainty on the trend. Our analysis shows that a long time series of in situ profile measurements of trace gases such as SF6 and CO2 can be a unique and useful indicator of stratospheric circulation variability on a range of time scales and an important contributor to help validate the stratospheric portion of global chemistry climate models. However, with only SF6 and CO2 measurements, the competing effects on mean age between mean circulation and mixing (tropical entrainment) are not uniquely separable.
Correlation between the channel‐bottom light intensity and channel‐base current of a rocket‐triggered lightning flash
Authors: Zhou M. , Wang D. , Wang J. , Takagi N. , Gamerota W. R. , Uman M. A. , Jordan D. M. , Pilkey J. T. , Ngin T.
Published: November 2014

The correlations between channel‐bottom light intensity and channel‐base current of all discharge processes of a rocket‐and‐wire‐triggered lightning flash, including initial continuous current (ICC) pulses, ICC pulse background continuing current (IBCC), return strokes, M components, and M component background continuing currents (MBCC), have been investigated. A rough linear correlation has been found between the current squared and the light intensity for ICC pulses (including peaks of different ICC pulses), IBCC, the initial rising stage (IRS) of return strokes (including current peaks of different strokes), and MBCC. The slopes of the correlation regression lines for the current squared versus light intensity of ICC pulses and IBCC are similar, but they are about 2–3 times smaller than the slopes of MBCC and 5–7 times smaller than the slopes of the IRS of return strokes. In contrast, a rough linear correlation has been found between the current and the light intensity for the later slow decay stage of return strokes and for the M components. The slopes of the correlation regression lines of the current versus the light intensity for these latter two processes are found to be similar. No simple correlation has been found between the current and the light intensity for the initial fast decay stage (IFDS) of return strokes. The duration of the IFDS of return strokes generally lasts from several microseconds to several tens of microseconds and is more or less directly proportional to the corresponding peak return stroke current squared. A time delay ranging from 12 µs to 300 µs has been found between the current and the light intensity of all ICC pulses and M components. The time delay decreases as the corresponding peak current increases.
Brain Evolution and Comparative Neuroanatomy
Authors: Powers Alice S
Published: November 2014

Brains have many diverse forms in different animal groups, from complex layered structures to simple nerve nets. The range of different brain forms is reflective of the huge variety of environmental niches and lifestyles in which organisms have been successful. Both simple and elaborate brains are adaptive, depending on the selective pressures to which organisms are subjected. In vertebrates, a basic plan can be recognised across groups, especially in the brainstem, but the forebrain of birds and mammals is much more elaborate than those of other vertebrates. Elaborate nervous systems have developed independently in some molluscs, arthropods and vertebrates. Correlated with this elaboration is the capacity for complex learning, which is highly developed in some molluscs, arthropods and birds and mammals. The presence of elaborated brains in disparate groups illustrates that evolution of the brain has not shown a trend from simple to complex, but rather has occurred independently in different lineages.

Key Concepts:

Two structures are homologous if they can be traced to a common ancestor. Because brains do not fossilise, establishment of brain homologies requires as much information as possible about the similarities between brains of different groups.

There is no trend in the evolution of the brain. Specialisations in brain traits develop in response to the demands of various environmental selective pressures. Many animals with simple nervous systems are very successful.

Two major groups of invertebrates can be distinguished: those with radial symmetry and those with bilateral symmetry. Those with radial symmetry have simple nervous systems with a ring of neurons, while bilaterally symmetrical organisms have concentrations of neurons in the head region.

Octopi, insects and crustaceans have elaborate brains, well‐developed eyes and extensive learning ability, rivalling that of mammals.

The brains of the earliest chordate ancestors of vertebrates had bilateral eyes, a diencephalon and hindbrain.

All vertebrates have the same subdivisions of the brain: the hindbrain, midbrain and forebrain (the diencephalon and telencephalon). The hindbrain is relatively conservative, retaining a recognisable structure in spite of many variations, whereas the forebrain shows more variability among vertebrate groups.

Twenty‐five cranial nerves can be recognised in vertebrates, innervating muscles of the head and specialized sense organs, including lateral line organs and taste buds on the body surface.

The vertebrate telencephalon includes a dorsal pallial area which differentiates into the cerebral cortex in mammals, but there is disagreement about the homologous areas in nonmammals.

Brains have evolved to enable organisms to compete successfully in different environmental niches and the adaptations they show reflect the demands of those environments.
DNAReplication: Mammalian
Authors: Smith Shanna J , Li Caroline M , Hickey Robert J , Malkas Linda H
Published: November 2014

Deoxyribonucleic acid (DNA)replication is an evolutionarily semi‐conserved process that involves a mechanism to unwind the parent DNA strand, the synthesis of identical daughter strands, and steps to terminate the sequence. Owing to the massive amount of genetic information needed to be copied error‐free, the replication of DNA within the mammalian chromosome is highly complex, requiring the simultaneous firing of multiple origins and processing of DNA at defined sites within the cells. This action requires the strict regulation and precise timing of numerous proteins, enzymes and substrates. These components critical to DNA replication will associate within these compartments in the cell to form replication factories during processing. Although many of the basic functions of DNA synthesis are well‐defined, there is still much yet to be understood regarding the machinery involved in the initiation, synthesis and termination of mammalian DNA replication.

Key Concepts:

Mammalian DNA replication occurs at specific regions within the cell.

Proteins necessary for DNA replication come together to form ‘replication factories’ within the nucleus.

The manner and timing of mammalian DNA replication is largely determined in G1 of the cell cycle.

The selection and timing of each replication site is controlled by a combination of primary sequences, kinase activation, transcription, and local chromatin environment.

The proteins thus far identified at the mammalian cell DNA replication fork include the MCM helicase complex, DNA pol α‐primase, PCNA, RFC, DNA pol δ, FEN1, RPA, DNA ligase I, topoisomerase I and II and RNAse H.

Termination of mammalian DNA replication is thought to be dependent on physical barriers within the replication factories, as opposed to actual termination sequences within the DNA structure.

In the event of replication fork stalling, repair pathways must be activated to halt cell cycle progression and repair the damage.
Plant Cell Growth and Elongation
Authors: Cosgrove Daniel J
Published: November 2014

Irreversible cell expansion is an essential process underlying plant growth and development. Growth begins with cell wall loosening which induces wall stress relaxation which in turn generates the reduced water potential that is needed for water uptake and volumetric expansion of the cell. Most growing cell walls consist of a cellulose scaffold embedded in a matrix of polysaccharides classified as pectins and hemicelluloses. Models of the growing cell wall are tentative hypotheses about how cell wall components are linked together to make a strong yet extensible wall and have implications about the mechanism of wall expansion. Recent evidence indicates that wall loosening by expansins and specific endoglucanases may be limited to specific regions (‘biomechanical hotspots’) where cellulose microfibrils come into close contact. The growing cell wall is dynamically modified by enzymes that change the structure of pectins and hemicelluloses, thereby altering their interactions with each other and with cellulose. Growth cessation is correlated with reduced expression of genes that promote wall loosening and changes in matrix polysaccharides that lead to a less extensible cell wall.

Key Concepts:

Irreversible cell expansion is an essential aspect of plant growth and morphogenesis.

Surface expansion of the cell wall may be highly localised, as in tip‐growing cells, or more evenly dispersed over the cell wall surface (‘diffuse growth’), occurs pattern common in most cells of the plant body.

Most cells undergo a relatively brief period of rapid cell expansion after they leave the meristem and before they differentiate into mature cells.

Expansive growth of plant cells requires simultaneous uptake of water into the cell and irreversible expansion of the cell wall.

Cell growth begins with cell wall loosening which leads to ‘stress relaxation’ of the cell wall which in turn creates the water potential difference needed for water uptake by the cell, resulting in the physical enlargement of the cell.

The growing cell wall is composed of a network of cellulose microfibrils embedded in pectins and hemicelluloses that make up the wall matrix; these materials combine to form a load‐bearing structure that controls cell mechanics and physically limits cell growth.

Deposition of new polymers to the wall is usually coordinated with surface expansion, but these are separable processes.

Plant cell walls enlarge more rapidly at low pH (‘acid growth’), a process that is mediated by nonenzymatic proteins named α‐expansins.

Several classes of enzymes modify the structure of pectins and hemicelluloses in the cell wall, but it is not clear whether such activity modulates growth in most cases.

Cessation of cell enlargement likely involves multiple processes, including tightening of the matrix‐cellulose network and reduced expression of wall‐loosening proteins.
Crystallization of Protein–
DNA
Complexes
Authors: Pakotiprapha Danaya , Jeruzalmi David
Published: November 2014

Determination of atomic resolution structures of protein–deoxyribonucleic acid (DNA) complexes using X‐ray crystallography requires preparation of high‐quality crystalline specimens. The preparation of such samples remains an empirical endeavour, more art than science. Nonetheless, decades of experience have yielded a large body of practical strategies and techniques towards this end. Such efforts with protein–DNA complexes enjoy special advantages, but also involve control of a larger set of variables. High purity, chemical and conformational, preparations of both macromolecules are important. Crystallogenesis of protein–DNA complexes is favoured by careful choice of the sequence and the terminal bases and/or base pairs of the DNA target. Modern crystallisation screens, which encapsulate the accumulated wisdom of prior investigations, serve as an excellent starting point for experimentation.

Key Concepts:

An atomic level analysis of a macromolecule by X‐ray crystallography requires preparation of high‐quality crystals of the entity of interest.

Preparation of crystalline specimens requires highly concentrated solutions of the molecules of interest. Success is favoured when high chemical and conformational purity has been achieved.

Extensive experience in preparation of protein crystals can be applied to growth of protein–DNA crystals. Additionally, the length, composition, and identity of the termini of the DNA molecule play significant roles in crystallisation.

Initial crystallisation trials are set up using a concentrated stock of protein–DNA complex of interest with premade formulations that sparsely sample crystallisation space. Precipitation and crystal formation under these conditions are used to direct efforts for further crystallisation experiments. The experiments are repeated until crystals suitable for X‐ray diffraction are obtained.
History of Cell Biology
Authors: Dröscher Ariane
Published: November 2014

Although egg cells are visible to the naked eye, the history of cell biology is closely coupled to that of microscopy. In nearly 350 years, cell research has produced an extraordinary rich panorama of studies, concepts and representations. Robert Hooke's analogy to honey bee cells, the transition from cellular tissue to single cells around the year 1800, Schleiden and Schwann's establishment of the cell as the elementary unit of life, the prominent status it gained during cytology's expansion to the other fields of biomedical enquiry, Schultze's definition as a clump of protoplasm containing a nucleus, the worlds of endocellular and ultrastructural organisation, the compartmentalization of the cell in the 1950s and 1960s, its role as map for biochemical and molecular research, all these are just few of the many historical answers to the question what a cell is and what it is good for?’

Key Concepts:

For the beginning of cell biology as a new research field it was not sufficient to be merely able to see cells.

The development of cell biology was coupled with the evolution of optical instruments and of anatomical theory.

One indispensable prerequisite for the formulation of the first cell theory was the shift from the concept of cellular tissue to that of cells as single units.

Cell research underwent ‘golden ages’ whenever cells were considered the basic units of life.

Many outstanding life scientists did not attribute central importance to cells.

The study of cells was (and still is) extraordinarily rich in different ways of seeing, describing, depicting and conceiving.

Though it originated from a specific theory, the history of cell biology is characterised by its growing independence from general theory.

Throughout its history cell biology was characterised by its ability to expand into neighbouring research fields and to integrate their concepts and methods.
Estimation of Species Trees
Authors: Mallo Diego , de Oliveira Martins Leonardo , Posada David
Published: November 2014

During the last decades, gene trees have been often interpreted as species phylogenies. However, the extensive gene tree discordance found in multi‐locus datasets has put into question this interpretation, and a variety of new methods that explicitly consider species trees have been proposed in recent years. Some of these explicitly consider evolutionary processes that can lead to true gene tree discordance, namely incomplete lineage sorting, gene duplication and loss and horizontal gene transfer. Choosing the most appropriate species tree method for the data at hand is not straightforward due to different data prerequisites, model assumptions, analytical strategies and computational implementations.

Key Concepts:

We could think of at least three different phylogenetic layers corresponding to species trees, locus trees and gene trees. These depict, respectively, the history of the sampled species, loci and genes copies.

Traditional phylogenetic inference has focused on the reconstruction of gene trees, assumed to be accurate proxies for species history.

True species, locus and gene trees can be incongruent due to the effect of evolutionary processes like incomplete lineage sorting, gene duplication and loss and horizontal gene transfer. This incongruence might appear larger due to estimation error.

Extensive gene tree incongruence unveiled in multi‐locus datasets has encouraged the development of methods that explicitly reconstruct species trees. The supermatrix approach combines loci into a super‐alignment and estimates the corresponding supergene tree. Supertree methods combine gene trees to obtain an estimate of the species tree. Other methods co‐estimate gene and species trees in a single step using full probabilistic models.

Different species tree methods require distinct data specifications, mainly related with the consideration of paralogs, number of sampled species, missing taxa and number of loci.

Rooting and reconstruction uncertainty must be carefully considered before choosing a species tree method.
Wernicke–Korsakoff Syndrome
Authors: Sechi Gian Pietro , Fancellu Laura , Doneddu Pietro , Sechi Elia
Published: November 2014

Wernicke–Korsakoff syndrome refers to a life‐threatening encephalopathy due to inadequate supply of thiamine (vitamin B1) to the brain. It is a combination of Wernicke encephalopathy (WE), an acute neuropsychiatric disorder fully responsive to prompt and adequate thiamine replacement, and Korsakoff syndrome (KS), the chronic, irreversible form of WE that does not remit with thiamine treatment. Thiamine deficiency can occur in any condition of unbalanced nutrition that lasts for 2–3 weeks. These include poor nutrition, chronic alcohol misuse, loss of thiamine owing to recurrent vomiting or malabsorption, increased thiamine requirements owing to chronic diseases, prolonged and excessive carbohydrate intake and gastrointestinal surgical procedures, in particular, patients after bariatric surgery. The diagnosis is clinical and is mainly supported by the dramatic improvement of neurological signs to parenteral thiamine. Neuroimaging studies are useful to confirm the diagnosis of both WE and KS. Patients with suspected thiamine deficiency should be treated immediately with parenteral thiamine at the doses deemed to be effective in the treatment of WE and prevention of KS.

Key Concepts:

Thiamine deficiency can occur in a myriad of clinical settings that include malnutrition, malabsorption and increased metabolism and in patients following bariatric surgery.

A thiamine deficiency that lasts for 2 to 3 weeks leads to Wernicke encephalopathy, an acute, life‐threatening disorder that is a medical emergency.

Wernicke encephalopathy is fully responsive to prompt and adequate thiamine replacement.

Untreated or inadequately treated Wernicke encephalopathy may lead to Korsakoff syndrome, a chronic amnesic encephalopathy that does not remit with thiamine treatment.

The goal of treatment of Wernicke encephalopathy is the immediate administration of high doses of parenteral thiamine deemed sufficient to prevent Korsakoff syndrome.
Mesostructured Intermetallic Compounds of Platinum and Non‐Transition Metals for Enhanced Electrocatalysis of Oxygen Reduction Reaction
Authors: Lang Xing‐You , Han Gao‐Feng , Xiao Bei‐Bei , Gu Lin , Yang Zhen‐Zhong , Wen Zi , Zhu Yong‐Fu , Zhao Ming , Li Jian‐Chen , Jiang Qing
Published: November 2014

Alloying techniques show genuine potential to develop more effective catalysts than Pt for oxygen reduction reaction (ORR), which is the key challenge in many important electrochemical energy conversion and storage devices, such as fuel cells and metal‐air batteries. Tremendous efforts have been made to improve ORR activity by designing bimetallic nanocatalysts, which have been limited to only alloys of platinum and transition metals (TMs). The Pt‐TM alloys suffer from critical durability in acid‐media fuel cells. Here a new class of mesostructured Pt–Al catalysts is reported, consisting of atomic‐layer‐thick Pt skin and Pt3Al or Pt5Al intermetallic compound skeletons for the enhanced ORR performance. As a result of strong Pt–Al bonds that inhibit the evolution of Pt skin and produce ligand and compressive strain effects, the Pt3Al and Pt5Al mesoporous catalysts are exceptionally durable and ≈6.3‐ and ≈5.0‐fold more active than the state‐of‐the‐art Pt/C catalyst at 0.90 V, respectively. The high performance makes them promising candidates as cathode nanocatalysts in next‐generation fuel cells.
Ordered Network of Interconnected SnO2 Nanoparticles for Excellent Lithium‐Ion Storage
Authors: Etacheri Vinodkumar , Seisenbaeva Gulaim A. , Caruthers James , Daniel Geoffrey , Nedelec Jean‐Marie , Kessler Vadim G. , Pol Vilas G.
Published: November 2014

An ordered network of interconnected tin oxide (SnO2) nanoparticles with a unique 3D architecture and an excellent lithium‐ion (Li‐ion) storage performance is derived for the first time through hydrolysis and thermal self‐assembly of the solid alkoxide precursor. Mesoporous anodes composed of these ≈9 nm‐sized SnO2 particles exhibit substantially higher specific capacities, rate performance, coulombic efficiency, and cycling stabilities compared with disordered nanoparticles and commercial SnO2. A discharge capacity of 778 mAh g–1, which is very close to the theoretical limit of 781 mAh g–1, is achieved at a current density of 0.1 C. Even at high rates of 2 C (1.5 A g–1) and 6 C (4.7 A g–1), these ordered SnO2 nanoparticles retain stable specific capacities of 430 and 300 mAh g–1, respectively, after 100 cycles. Interconnection between individual nanoparticles and structural integrity of the SnO2 electrodes are preserved through numerous charge–discharge process cycles. The significantly better electrochemical performance of ordered SnO2 nanoparticles with a tap density of 1.60 g cm–3 is attributed to the superior electrode/electrolyte contact, Li‐ion diffusion, absence of particle agglomeration, and improved strain relaxation (due to tiny space available for the local expansion). This comprehensive study demonstrates the necessity of mesoporosity and interconnection between individual nanoparticles for improving the Li‐ion storage electrochemical performance of SnO2 anodes.
Dominating Energy Losses in NiO p‐Type Dye‐Sensitized Solar Cells
Authors: Daeneke Torben , Yu Ze , Lee George P. , Fu Dongchuan , Duffy Noel W. , Makuta Satoshi , Tachibana Yasuhiro , Spiccia Leone , Mishra Amaresh , Bäuerle Peter , Bach Udo
Published: November 2014

Nickel oxide based p‐type dye‐sensitized solar cells (DSCs) are limited in their efficiencies by poor fill factors (FFs). This work explores the origins of this limitation. Transient absorption spectroscopy identifies fast recombination between the injected hole and the dye anion under applied load as one of the predominant reasons for the poor FF of NiO‐based DSCs. A reduced hole injection efficiency, ηINJ, under applied load is found to play an equally important role. Both, the dye regeneration yield, ΦREG, and ηINJ decrease by approximately 40%–50% when moving from short‐ to open‐circuit conditions. Spectroelectrochemical measurements reveal that the electrochromic properties of NiO are a further limiting factor for the device performance leading to variable light‐harvesting efficiencies, ηLH, under applied load. The peak light‐harvesting efficiency decreases from 63% at short circuit to 57% at 600 mV reducing the FF of NiO DSCs by 5%. This effect is expected to be more pronounced for future devices with higher operating voltages. Incident, photon‐to‐electron conversion efficiency front–back analysis at applied bias is utilized to characterize the interfacial charge recombination. It is found that the recombination between the injected hole and the redox mediator has a surprisingly small effect on the FF.
Mechanically Robust BiSbTe Alloys with Superior Thermoelectric Performance: A Case Study of Stable Hierarchical Nanostructured Thermoelectric Materials
Authors: Zheng Yun , Zhang Qiang , Su Xianli , Xie Hongyao , Shu Shengcheng , Chen Tianle , Tan Gangjian , Yan Yonggao , Tang Xinfeng , Uher Ctirad , Snyder G. Jeffrey
Published: November 2014

Bismuth telluride based thermoelectric materials have been commercialized for a wide range of applications in power generation and refrigeration. However, the poor machinability and susceptibility to brittle fracturing of commercial ingots often impose significant limitations on the manufacturing process and durability of thermoelectric devices. In this study, melt spinning combined with a plasma‐activated sintering (MS‐PAS) method is employed for commercial p‐type zone‐melted (ZM) ingots of Bi0.5Sb1.5Te3. This fast synthesis approach achieves hierarchical structures and in‐situ nanoscale precipitates, resulting in the simultaneous improvement of the thermoelectric performance and the mechanical properties. Benefitting from a strong suppression of the lattice thermal conductivity, a peak ZT of 1.22 is achieved at 340 K in MS‐PAS synthesized structures, representing about a 40% enhancement over that of ZM ingots. Moreover, MS‐PAS specimens with hierarchical structures exhibit superior machinability and mechanical properties with an almost 30% enhancement in their fracture toughness, combined with an eightfold and a factor of six increase in the compressive and flexural strength, respectively. Accompanied by an excellent thermal stability up to 200 °C for the MS‐PAS synthesized samples, the MS‐PAS technique demonstrates great potential for mass production and large‐scale applications of Bi2Te3 related thermoelectrics.
A conceptual model for chemical product design
Authors: Bernardo Fernando P. , Saraiva Pedro M.
Published: November 2014

The fundamental principles of chemical product design and associated systematic tools, within a broad domain of chemical products including molecules, formulations, and devices, are still under development. In this article, we propose a simple and fundamental conceptual model that defines the chemical product design problem as the inversion of three central design functions: quality, property, and process functions. The classic iterative cycles of product design problems may be envisioned as alternating between inversion and evaluation of these three functions, or in other words alternating between synthesis and analysis of solutions. On top of the proposed basic structure of the overall design problem, we then discuss the formulation of some subproblems as optimization problems and describe some useful solution tools. Three application examples are provided, including a more detailed case of formulation of a pharmaceutical ointment. © 2014 American Institute of Chemical Engineers AIChE J, 61: 802–815, 2015
Effect of dielectric packing materials on the decomposition of carbon dioxide using DBD microplasma reactor
Authors: Duan Xiaofei , Hu Zongyuan , Li Yanping , Wang Baowei
Published: November 2014

Carbon dioxide (CO2) decomposition was performed at a normal atmosphere and room temperature in dielectric barrier discharge microplasma reactors to reduce CO2 emissions and convert CO2 into valuable chemical materials. The outlet gases, including CO2, CO, and O2, were analyzed with gas chromatography. The results indicated that the conversions of CO2 in dielectric material‐packed reactors were all higher than that in nonpacked reactors. Particle size, dielectric constant, particle morphology, and acid‐base properties of the dielectric materials (including quartz wool, quartz sand, γ‐Al2O3, MgO, and CaO) all affected the CO2 decomposition process. The conversion of CO2 and energy efficiency achieved the highest values of 41.9 and 7.1% in a CaO‐packed reactor for the higher dielectric constant and basicity of CaO. Quartz wool was also an excellent dielectric packing material because its fiber structure provided rigid sharp edges. © 2014 American Institute of Chemical Engineers AIChE J, 61: 898–903, 2015
Economic model predictive control of nonlinear process systems using empirical models
Authors: Alanqar Anas , Ellis Matthew , Christofides Panagiotis D.
Published: November 2014

Economic model predictive control (EMPC) is a feedback control technique that attempts to tightly integrate economic optimization and feedback control since it is a predictive control scheme that is formulated with an objective function representing the process economics. As its name implies, EMPC requires the availability of a dynamic model to compute its control actions and such a model may be obtained either through application of first principles or through system identification techniques. In industrial practice, it may be difficult in general to obtain an accurate first‐principles model of the process. Motivated by this, in the present work, Lyapunov‐based EMPC (LEMPC) is designed with a linear empirical model that allows for closed‐loop stability guarantees in the context of nonlinear chemical processes. Specifically, when the linear model provides a sufficient degree of accuracy in the region where time varying economically optimal operation is considered, conditions for closed‐loop stability under the LEMPC scheme based on the empirical model are derived. The LEMPC scheme is applied to a chemical process example to demonstrate its closed‐loop stability and performance properties as well as significant computational advantages. © 2014 American Institute of Chemical Engineers AIChE J, 61: 816–830, 2015