bluuebunny/crossref_metadata_2025 huggingface dataset:
Underwater Technology Platforms
Authors: Sørensen Asgeir J. , Ludvigsen Martin
Published: January 2018

Recent developments in underwater technology platforms including control methods, sensors, manipulators, and tools have become an enabler for more advanced and efficient underwater operations for the purpose of marine science and industrial applications such as offshore oil and gas, marine minerals, fisheries, aquaculture, and offshore renewable energy. The underwater operations may vary from mapping, monitoring, and sampling of the marine environment to inspection, maintenance, and repair (IMR) of submerged infrastructure used in, for example, subsea oil and gas. The new technology and methodology have created new opportunities for integrated operations using suitable platforms and sensors dynamically addressing the different steps in an operation from definition, planning, and replanning of mission with adaptive selection of parameters, sensor, and underwater technology platforms for knowledge generation as basis for decision‐making. This section gives an overview of the different underwater technology platforms, sensors, and tools that may be used in underwater operations. Recent research efforts on control methodology going from teleoperation to increased level of autonomy will also be presented. Results and experience from selected field trials integrating different sensors and underwater platforms such as autonomous underwater vehicles (AUVs), remotely operated vehicles (ROVs), and ship‐based systems carried out in the Norwegian coastal will be presented.
Subsea Processing of Multiphase Flow
Authors: Lam Loh W.
Published: January 2018

Subsea processing involves manipulating the well stream between downhole of the wellhead and host. Subsea processing applications are hydrocarbon boosting (pumping), separation systems, gas compression, multiphase flowmetering, and produced water and gas reinjection. Prerequisites and enablers for the abovementioned applications are long‐distance/high voltage power, advanced process monitoring and control, cost‐efficient installation, maintenance and modular design for intervention, and retrieval (Eidsmoen, 2011).
Riser Technology
Authors: Thomas William
Published: January 2018

The system and its components that comprise a subsea riser is described. Subsea riser systems can be configured in a number of ways that can be strategically employed to improve operations (such as catenary versus top tensioned). A subsea riser system comprises a multitude of components that provide a variety of individual functions (such as a swivel joint), which together in a system meets the overall objective. Some and many of the available riser solutions are dictated by preference rather than need (such as dual versus single casing risers). This article is written to provide an overview and introduction to subsea riser systems.
Explosion and Fire Risk
Authors: Sari Ali
Published: January 2018

Accidental loadings such as fire and blast constitute a great majority of potential and actual fatalities in offshore operations. In order to prevent human loss and for a safe design or assessment of an offshore asset, the risks of these accidental loadings need to be quantified in terms of both probability/frequency and consequence aspects.

This article presents risk‐based methodologies for the analysis of interaction between ship and offshore structures when the offshore structures are subjected to blast and fire loadings. These methodologies outline the state‐of‐the‐art approaches utilized in offshore industry to address the blast and fire issue in design and assessment of offshore structures. Both frequency analysis and consequence analysis are described in detail.
Concrete Gravity Platforms
Authors: Olsen Tor O.
Published: January 2018

Concrete gravity platforms are structures resting on the seabed. They must have sufficient weight to remain in place when subjected to waves, current, and wind. Their configuration in contact with the sea bottom must be adapted to the specific soil conditions at the site.

At the time of this writing (2016), there were 50 major offshore concrete platforms for the oil and gas industry in the world, almost all of them of the gravity type.

Offshore platforms are not builtin situ, as most land‐based structures are, but are built somewhere else and towed to and installed at the site. This unique way of construction favors deep fiords that give sheltered construction sites and sufficient depth for construction. Building the topside structure and the concrete substructure simultaneously, and then mating the two in sheltered waters before towing the complete platform to site, saves valuable time. When fiords have not been available, concrete gravity platforms have also been constructed in a dry dock, and the topside is lift‐installed. Smaller structures may be built on barges.
Production Jack‐Up
Authors: Thomas Pierre‐Armand
Published: January 2018

Jackup MODUs (mobile offshore drilling units) have been extensively used for exploration drilling in water depth up to 100 m in a harsh environment, such as the North Sea, and up to 120 m under less severe sea conditions. This article will look at their design conditions, design briefs, and their definitions and applicability.
The
J
ack‐
U
p Platform Overview
Authors: Boswell Laurie F.
Published: January 2018

A Jack‐Up platform can float and be transported, can be elevated when it arrives on location, and its legs will rest on the sea bed. After an appropriate and rigorous site assessment, the unit will be ready for operation. Due to the compliant characteristics of the structural system, difficult challenges must be overcome by designers and operators. Generally, these challenges are more complex than most offshore structures, and the later section in this article related to the management of hazards endorses this comment.

This section is an overview of the main characteristics of these mobile units. A modern Jack‐Up can weigh up to 20,000 tonnes and be capable of operating in 150 m of water in a very harsh ocean environment. Jack‐Up platforms are designed and constructed to satisfy the rules of classification societies, and classification is a comprehensive verification procedure. In this respect, they may be regarded as mobile units together with ships and other marine structures. For this reason, the classification of Jack‐Ups has been considered in the Marine Operations chapter of this Encyclopedia.

The main structural features are associated with the hull and the legs and foundation, and these are reviewed in this introduction. However, separate sections for Jack‐Up structural design and foundation design have been included in the Jack‐Up chapter. Transportation is a critical stage when the unit can become unstable, but elevating the structure and the process of jacking can also be problematic. Transportation has been considered as a separate section in this article, and the examples of accidents as case studies demonstrate the dangers associated with the critical stages of operation.

Consideration has been given to the use of high strength steel in this review, but sections related to Fatigue and Fracture Mechanics have been provided separately in the Jack‐Up chapter. The section related to Marine Warranty Survey aspects brings together many of the features of Jack‐Up operations, and the potential of Jack‐Up risk and reliability studies for risk assessment of various operating stages has been explored in the Reliability section within this chapter.
Exploration: Seismic Surveys, Drilling, Logging, and Cores
Authors: Dirkzwager Jozina B.
Published: January 2018

Advances in offshore engineering technologies and naval architecture are greatly influencing the ability of the oil and gas industry to explore for, drill, and produce hydrocarbon accumulations offshore. The exploration process encompasses all aspects related to mapping and analyzing a petroleum system, ranging from source rock to reservoir as well as from trap type to caprock, and includes identifying those locations that are most likely to contain a hydrocarbon accumulation in the subsurface. Tools used by oil and gas explorers are mostly based on physics and depend in part on fundamental variables in the earth's physical condition, for example, changes in gravity, magnetic field, fluids, and electrical resistance. The collection of rock and fluid information of the subsurface before and during drilling is essential in assessing the type of producible hydrocarbon or other. While exploration was historically done on land (e.g., mid‐1800s in Texas, USA), with ongoing technological advances it is now also routinely carried out offshore on a large scale and worldwide. It is beyond the scope of this article to elaborate on all possible aspects of the exploration process, and therefore only some of the better known techniques are highlighted.
Offshore Petroleum Production Technologies—Overview
Authors: Tyagi Mayank
Published: January 2018

This article presents an overview of offshore petroleum production technologies. In particular, a brief overview of floating production platforms is presented along with subsea production system at the seafloor and its components. Flow assurance is discussed to highlight some of the challenges in maintaining the offshore petroleum production over long durations.
New Frontiers and Deepwater Technology/Ultradeepwater Challenges (with Safety Systems)
Authors: Naik Pramod
Published: January 2018

Blowout preventer
s (
BOP
s) are pressure control equipment used as a safety barrier by controlling the wellhead pressure and the flow rates encountered in the well. New deepwater frontiers to exploration require high pressure BOPs. A blowout is an uncontrolled release of crude oil, natural gas, or well fluids into the atmosphere or into an underground formation (underground blowouts) following failure of all well barriers. There have been 173 blowouts that have occurred during January 1980 to January 2008 in the United States (US),
Gulf of Mexico
(
GOM
), and Outer Continental Shelf (OCS). There is a need in the oil and gas industry to explore, develop, and pursue the 20‐ and 25‐ksi rated BOP product line. For example, Maersk Drilling ordered the first 20,000‐psi (20 ksi) BOP made by
general electric
(
GE
) Oil and Gas, which is due in 2018. Other BOP makers are also developing 20 ksi BOP stack.
Offshore Spill Response Systems: Capping and Containment
Authors: Tyagi Mayank
Published: January 2018

This article provides an overview of the capping and containment‐related equipment that is generally referred to as
source control and containment equipment
(SCCE) technologies. In particular, the critical role of capping stack is highlighted. Other related equipment details for containment domes, dispersants, debris removal, etc., are also provided here to elucidate the system usage during offshore oil spill response.
Resource Development in Arctic Regions
Authors: Kenny Shawn , Jukes Paul
Published: January 2018

Hydrocarbon basins in global arctic regions hold significant resources with economic potential to support an array of economic sectors including energy, transportation, petrochemical, agricultural, and manufacturing industries. Due to the harsh physical environment, northern and arctic regions present significant technical and logistical challenges that influence the development of engineering solutions through the design process and may affect the project viability and sanction with respect to technical or economic factors. One of the more significant hazards and extreme loading events encountered is ice gouging due to the interaction of ice features with the seabed subject to environmental driving forces. Trenching and pipeline burial is viewed as one of the most effective mitigation techniques used to promote pipeline serviceability and reduce the risk of pipeline damage; however, there are limitations and constraints with current technologies with respect to the maximum trenching depth and production rates that affect project logistics and economic risk. In addition, there are other physical environmental factors that present challenges including the short open water season, low temperatures, and presence of special terrain characteristics (e.g., hardpan, permafrost, massive ground ice). Current practice used to define system demand (i.e., geotechnical loads) and system capacity (i.e., pipeline mechanical performance) has limitations due to inherent uncertainties with the statistics of physical data sets, experimental techniques, and engineering models used in the analysis. Advancements in computational methods have provided improved engineering tools to analyze these complex nonlinear processes with probabilistic methods providing an objective framework to assess design options with respect to technical, economic, and environmental criteria that meet specified target safety levels. Consideration of cumulative effects, climate change, and sustainability factors add an additional layer of complexity to the engineering framework in terms of social context and political values.
Geotechnical Interpretative Report
Authors: Joer Hackmet
Published: January 2018

A geotechnical interpretative report (GIR) provides a vital link between the factual laboratory and site investigation data and the analyses performed during geotechnical engineering design. A good GIR brings together all available data sets to form a coherent ground model that provides geotechnical values for the intended design purpose or purposes. Consequently, the GIR must be prepared by a qualified and experienced team of geotechnical engineers, engineering geologists, and geophysicists. Unlike other engineering material such as steel and concrete, the strength of a soil is highly dependent on the direction of shearing, the rate of loading, and the drainage conditions during loading; to make things even more complicated, the stiffness of soil is also highly nonlinear. Unfortunately, this complex variability makes it commercially impractical to develop a generic GIR that covers all potential design scenarios—instead, GIRs tend to be produced for a defined range of purposes or even a single purpose. The complexity of GIRs depends significantly on the design purpose—for example, the design of a noncritical lightly loaded structure in uniform soils would require a much simpler GIR than the design of a heavily loaded critical structure in complex soils.
Spudcan–Seabed Interaction
Authors: Bienen Britta , Hossain Muhammad S.
Published: January 2018

Most offshore drilling in shallow to moderate water depths is performed from self‐elevating jack‐up rigs due to their proven flexibility, mobility, and cost‐effectiveness. Today's jack‐ups typically consist of a buoyant triangular platform supported by three independent truss legs, each attached to a large 10–20 m diameter spudcan, which are jacked into the seabed. These transfer the loads from the platform to the seabed soil. This article provides an overview of the state of practice of geotechnical design considerations for spudcan–seabed interaction, covering the full life cycle including (i) installation, (ii) operation, and (iii) demobilization.
Numerical Modeling for Geotechnical Design
Authors: Wang Dong
Published: January 2018

Although the limit equilibrium methods and mixed empirical–numerical methods are widely used in routine design of offshore geotechnical engineering, the finite element (FE) approaches have become the routine “calculator” for greater challenges. The key questions of FE modeling are discussed, including (i) the soil models in terms of monotonic and cyclic loadings; (ii) drained, undrained, or partially drained conditions; (iii) the influence of inertia; and (iv) the selection between small strain and large deformation analyses. Popular commercial FE programs and several typical offshore applications are addressed as well.
Seabed Processes: Sediment Transport, Scour, and Sedimentation
Authors: Draper Scott , Harris John M. , Cheng Liang , White David J.
Published: January 2018

In many offshore locations the seabed is mobile due to the action of currents and/or waves. The criteria for mobility (sediment transport) is that the shear stress imparted by the currents and/or waves exceeds the resisting forces holding the sediment in place.

When a temporary or permanent structure is placed onto the seabed, its presence disturbs the natural flows in a way that can result in spatial variations in sediment transport close to the structure. This can result in net erosion (i.e., scour) or accumulation (i.e., sedimentation) of sediment in the vicinity of the structure. The extent and rate of scour and sedimentation are dependent on a number of factors, including the near bed flow conditions, the local sediment properties, and the structure geometry. Model scale experiments, field data, and numerical models may be used to develop predictions of scour and sedimentation.

Scour and sedimentation may be problematic or beneficial for the stability of offshore structures. For offshore platforms, for example, scour can lead to undermining and instability. In this scenario, scour protection is often used to mitigate scour. Alternatively, for subsea pipelines, scour may lead to self‐burial and improved stability. In this scenario, actions may be undertaken to enhance seabed mobility.
Ultrasound
Authors: Vervloesem, (FNI) Walter
Published: January 2018

For many years, SDT International has been pioneering ultrasound applications and providing solutions for both the marine and shore‐based industry. Based on the fact that friction, impact or turbulent flow generate ultrasound, many shipboard equipment related failures can be detected in an infant stage and well before the equipment will suffer permanent damage. State of the art technology allows to monitor the condition of shipboard equipment in the manual, automatic and even on‐line mode and data produced allow for further and in‐depth study, analysis and failure finding. Using the correct ultrasonic equipment, monitoring techniques and appropriate software suites allows ship owners and managers to analyze data and boost their on board maintenance program, improve safety, enhance reliability and guarantee availability. The proven track record of ultrasound for many applications makes that ultrasound monitoring equipment should be in the toolbox of those in charge of the ship's maintenance program.
Internal Corrosion Considerations for Offshore Oil and Gas Production (Downhole and Production)
Authors: Caldwell Eric
Published: January 2018

The topic of subsea internal downhole and production corrosion is a major problem area since direct inspection or monitoring is complex and very costly and in some deep water cases virtually impossible. Additionally, there are no completely accepted codes, standards, or recommended practices. In contrast to external sea water corrosion, where code‐driven cathodic protection, coatings, and inspection surveys can be very successful, the internal corrosion is heavily reliant on the selection of good materials and performance under steady and nonsteady multiphase fluid flows. For the favored steel‐ based solutions, corrosion assessment and control are dependent on a corrosion allowance plus reliable inhibitors and monitoring. If the fluids are too corrosive, the selection of appropriate corrosion‐resistant alloys (CRAs) can be applied. This section presents the various understandings and options available to practicing engineers and technologists. The complexities and differences between vertical downhole pipe and essentially horizontal lines and equipment are discerned. Guidelines are given to help describing and controlling the most common challenges, namely, general and localized corrosion mechanisms, erosion, degradation, and environmental cracking issues faced by the industry.
Offshore Life Cycle Materials Performance
Authors: Martin Tim , Singh Binder
Published: January 2018

Deepwater equipment design and layout are described alongside the material requirements and environments encountered in a typical deepwater development. Alloys of construction and internal corrosion environments are discussed and the challenges associated with the full life cycle integrity are outlined. The authors conclude with some remarks and recommendations relating to the activities necessary to ensure the integrity over the life of a development.
Suction Caisson Anchors
Authors: Gourvenec Susan , Clukey Ed
Published: January 2018

Suction caissons are a class of embedment anchor used to secure floating facilities to the seabed. They comprise large diameter cylinders, typically in the range of 3–8 m, open at the bottom and closed at the top, and generally with a length to diameter ratio L/D in the range 3–6. Suction caissons are so called due to the use of suction to achieve installation to the target depth of penetration over that achievable with the caisson dead weight. This article outlines the types and applications of suction caisson anchors used offshore; the basis of design, including installation and in‐service conditions and mooring chain response; formal design guidance and factor of safety approaches. A wide range of issues that need to be considered for suction caisson anchors is discussed in this article, however, no attempt is made to provide detailed solutions for the different aspects that need to be considered, since these are well documented in industry design guidelines and the wider literature.
Trafficability of Seafloor Vehicles
Authors: Machin Jon
Published: January 2018

This article discusses key aspects of mobility and trafficability applicable to the operation of the tracked mining vehicle on very soft clays. Good mobility requires both sufficient traction and sufficient bearing capacity if the vehicle is to progress steadily. Lack of mobility and/or total immobilization would require recovery and repositioning the vehicle with an associated negative impact on productivity. Historically, mobility problems with tracked subsea vehicles (such as trenching machines) have been a common occurrence in the offshore industry. As a result, an understanding of the terramechanics involved has evolved, and significant improvements in tracked vehicle reliability and productivity are definitely seen during the past 5–10 years. Based on such recent advances, it is recommended to develop a modern mobility envelope approach such that the operation can be defined for particular conditions based on the resultsof high quality seabed survey data. Such an approach is discussed in the following article in more detail.
System Design and Integration
Authors: Twomey Bernard
Published: January 2018

The promise of improved features, performance, and efficiency for ship operation from higher levels of integration of ship's systems has come with the unwelcome side effect of increasing instances of compromised and lost ship's capability.

The main problem stems from general misunderstanding and poor implementation of system design and integration processes. This is made worse by the procurement and supply chain arrangements of a marine industry, which is still procuring on the basis of discrete subsystems and not following good system design and integration principles.

Other industries have sought the benefits from highly integrated systems, and there are some lessons to be learnt by the marine sector from their experience.

This article gives examples of problems that are typical in the marine sector now that suppliers are providing systems with the provision for, and the expectation that their products will form part of, complex integrated solutions. It then gives examples of system design and integration approaches taken by other industries where the use of large‐scale integrated systems is a normal part of design solutions.

The challenge for the marine sector is discussed, specifically using principles for integrated systems that have been defined by the Royal Academy of Engineering as a benchmark, drawing on conclusions and recommendations made recently by Charles Haddon‐Cave QC in his review of the 2006 RAF Nimrod crash in Afghanistan. In respect of the challenges for the marine sector, particular attention has been given to how change must be embraced if it is to maintain its ability to provide assurance that modern ships meet an acceptable level of safety throughout their operational life.
Configuration Management as a Risk‐Based Tool in Managing Dependability of Complex Software‐Based Systems
Authors: Twomey Bernard J
Published: January 2018

The increasing reliance upon complex systems in marine operations brings a corresponding need to ensure that these systems are demonstrably dependable in use. Furthermore, in order to be truly effective, integrated systems must be developed such that they function as a seamless whole fulfilling operational needs. Ensuring that the integrated systems are traceable throughout the systems lifecycle has been addressed in numerous standards, but the application in the marine sector has been limited, resulting in significant financial loss to the client. This article will emphasize the importance of shipowners' configuration management (CM) during a systems lifecycle and identifies benefits of having a CM discipline in place to help manage the risks associated with software maintenance.

Numerous standards have been produced to deal with CM, and the article will look at CM with respect to the International Standards ISO 17894 “General Principles for the Development and Use of Programmable Electronic Systems in Marine Applications,” and BS ISO 10007:2003, Quality management systems—Guidelines for CM.

From the platform of these standards, the article promotes good systems engineering practice, in managing the risks associated with through life software maintenance and seeks to rationalize the ideals with the current practices of the marine sector. In adopting the methodology, it is contended that the goal of effectively managing the automation systems now found in the marine sector can be realistically achieved.

Key CM functions (i.e., CM planning, CM identification, change control, impact analysis, and CM audit) and their respective roles for new build and existing ship implementation are described. In addition, this article identifies some new opportunities in identifying future risks associated with obsolescence of the programmable electronic systems.
Knowledge Management and Practical Safety
Authors: Wittkower Robert S.
Published: January 2018

Knowledge management and practical safety with its related accident investigation process remain prominent in the oil and gas industry, especially offshore. Historically, these topics come into focus during times of catastrophe. The Piper Alpha incident for the UK Health and Safety Executive and recent events in USA demonstrate how regulatory changes are forefront in times of crisis. The safety case regime and the SEMS (Safety Environmental Management System) regulations changed the landscape of offshore safety. Historically the past proclaims the future over a period of decades so that a “Wake‐Up” call is for program gap analysis to detect which is unknown and proceed forward with continuous improvement. Program fundamentals, resources, key aspects, and the role of the executive in leadership and accountability are stated. Accident investigation plays a supporting role, and significant advances in the field are available and are often used; yet, the industry fundamentals in this area remain viable and cost‐effective. Active engagement, leadership, processes, risk assessment, and knowledge management remain as program essentials.
Photogenerated Free Carrier‐Induced Symmetry Breaking in Spherical Silicon Nanoparticle
Authors: Rudenko Anton , Ladutenko Konstantin , Makarov Sergey , Itina Tatiana E.
Published: January 2018

All‐dielectric nonlinear nanophotonic devices are extremely prospective for ultrafast optical signal processing at the nanoscale. High refractive index (e.g., silicon) nanoparticles supporting magnetic optical response are shown to be suitable for ultrafast all‐optical modulation. A strong modulation of the dielectric permittivity is achieved via photogeneration of free carriers in the regime of simultaneous excitation of both the electric and magnetic Mie resonances and the off‐resonant regimes, resulting in an effective transient reconfiguration of nanoparticle scattering properties. Here, the effects of the related optical inhomogeneities in 3D are examined by coupling numerical electrodynamics with material ionization. Based on the computational results, the possibility of a deeply subwavelength transient refractive index reconfiguration inside spherical silicon nanoparticles is proposed. In particular, a symmetry breaking in the initially symmetrical nanoparticle is revealed, arising during ultrafast photoexcitation below and near the magnetic dipole resonance. The proposed ultrafast breaking of the nanoparticle symmetry paves the way to novel opportunities for nonlinear optical nanodevices.
Cyclopropenylgold(I) Complexes as Aurated Carbenoids or Quasi‐Carbenes
Authors: Mulks Florian F. , Antoni Patrick W. , Rominger Frank , Hashmi A. Stephen K.
Published: January 2018

Highly strained hydrocarbons have always been a research target of high interest. Due to their untypical electronic structure, they show interesting reactivity patterns and can easily be activated by π‐coordination to or insertion reactions with metal complexes. Herein we report the synthesis of a range of 3,3‐disubstituted cyclopropenylgold(I) complexes. The synthesis of such compounds with a metal, which usually easily activate cyclopropenes is a double‐edged sword. We found σ‐bound vinylic gold to generally have a strong stabilizing effect in terms of ring strain. The complexes show a strong distortion, preactivating the cyclopropenyls towards the ring‐opening mode which thermally generates 1‐aurated vinylcarbenes which is reflected by a much faster conversion (Ea of 10 kcal/mol instead of 40 kcal/mol, the reaction proceeds at temperatures as low as −20 °C instead of 200 °C reported in the literature). In 3‐phenyl‐cyclopropenyl complexes, these could be trapped intramolecularly to give indenylgold(I) complexes. The properties of these highly strained complexes were investigated, utilizing a range of analytical and experimental procedures and Kohn‐Sham density functional theoretic methods.

magnified image
Runx2/Osterix and Zinc Uptake Synergize to Orchestrate Osteogenic Differentiation and Citrate Containing Bone Apatite Formation
Authors: Fu Xuekun , Li Yunyan , Huang Tongling , Yu Zhiwu , Ma Kun , Yang Meng , Liu Qingli , Pan Haobo , Wang Huaiyu , Wang Junfeng , Guan Min
Published: January 2018

Citrate is essential to biomineralization of the bone especially as an integral part of apatite nanocomposite. Citrate precipitate of apatite is hypothesized to be derived from mesenchymal stem/stromal cells (MSCs) upon differentiation into mature osteoblasts. Based on 13C‐labeled signals identified by solid‐state multinuclear magnetic resonance analysis, boosted mitochondrial activity and carbon‐source replenishment of tricarboxylic acid cycle intermediates coordinate to feed forward mitochondrial anabolism and deposition of citrate. Moreover, zinc (Zn2+) is identified playing dual functions: (i) Zn2+ influx is influenced by ZIP1 which is regulated by Runx2 and Osterix to form a zinc‐Runx2/Osterix‐ZIP1 regulation axis promoting osteogenic differentiation; (ii) Zn2+ enhances citrate accumulation and deposition in bone apatite. Furthermore, age‐related bone loss is associated with Zn2+ and citrate homeostasis; whereas, restoration of Zn2+ uptake alleviates age‐associated declining osteogenic capacity and amount of citrate deposition. Together, these results indicate that citrate is not only a key metabolic intermediate meeting the emerging energy demand of differentiating MSCs but also participates in extracellular matrix mineralization, providing mechanistic insight into Zn2+ homeostasis and bone formation.
The Physics of Small Molecule Acceptors for Efficient and Stable Bulk Heterojunction Solar Cells
Authors: Gasparini Nicola , Wadsworth Andrew , Moser Maximilian , Baran Derya , McCulloch Iain , Brabec Christoph J.
Published: January 2018

Organic bulk heterojunction solar cells based on small molecule acceptors have recently seen a rapid rise in the power conversion efficiency with values exceeding 13%. This impressive achievement has been obtained by simultaneous reduction of voltage and charge recombination losses within this class of materials as compared to fullerene‐based solar cells. In this contribution, the authors review the current understanding of the relevant photophysical processes in highly efficient nonfullerene acceptor (NFA) small molecules. Charge generation, recombination, and charge transport is discussed in comparison to fullerene‐based composites. Finally, the authors review the superior light and thermal stability of nonfullerene small molecule acceptor based solar cells, and highlight the importance of NFA‐based composites that enable devices without early performance loss, thus resembling so‐called burn‐in free devices.
Scalar mixing in anisotropic turbulent flow
Authors: Nguyen Quoc , Papavassiliou Dimitrios V.
Published: January 2018

While turbulent mixing has been studied extensively in homogeneous turbulence, chemical engineering processes where mixing is important are anisotropic. In anisotropic turbulence, the interplay between convection and diffusion is critical. Flow in an infinite channel is utilized here with clouds of scalars released instantaneously at different distances from the wall and at Schmidt numbers between 0.7 and 2400. Qualitative and quantitative measures of mixing efficiency and intensity are defined and the dynamics of mixing are explored. It is found that molecular diffusivity can even hinder mixing in some instances, because it affects the development of the cloud of the released scalars from regions within the viscous wall layer. Another finding is that while one would expect mixing to occur mostly in the space between two points of release, considerable amount of mixing could take place outside of this region and closer to the wall. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2803–2815, 2018
Hydrothermal pretreatment for deconstruction of plant cell wall: Part II. Effect on cellulose structure and bioconversion
Authors: Yao Kun , Wu Qinfeng , An Ran , Meng Wei , Ding Mingzhu , Li Bingzhi , Yuan Yingjin
Published: January 2018

Influences of both ultrastructural modification of cellulose after hydrothermal pretreatment and products derived from lignin‐carbohydrate complex (LCC) on the subsequent enzymatic digestibility and fermentation were studied in this study. Under hydrothermal conditions, it was found that the rearrangement of hydrogen bonding pattern in cellulose via allomorph and conformational changes which was mainly severity‐dependent increased the numbers of water‐exposed glycosidic bond and the formation of “amorphous‐like” cellulose fibril facilitated enzymatic hydrolysis. Pseudo lignin, soluble xylo‐oligomers, phenols and degradation products from high severity impeded enzymatic digestion. LCC and phenols which were rich in pH‐controlled prehydrolyzate did not sufficiently inhibit yeast while furans and some aromatics which were rich in high‐severity prehydrolyzate might be potential inhibitors. Trade‐off phenomenon was solved by pH‐controlled operation and high yields in both glucose (83–93%) and xylose (75–80%) were simultaneously obtained. The final ethanol yield from cellulose to ethanol reached as high as 84–93%. © 2018 American Institute of Chemical Engineers AIChE J, 64: 1954–1964, 2018
The Chern‐Simons Current in Systems of DNA‐RNA Transcriptions
Authors: Capozziello Salvatore , Pincak Richard , Kanjamapornkul Kabin , Saridakis Emmanuel N.
Published: January 2018

A Chern‐Simons current, coming from ghost and anti‐ghost fields of supersymmetry theory, can be used to define a spectrum of gene expression in new time series data where a spinor field, as alternative representation of a gene, is adopted instead of using the standard alphabet sequence of bases. After a general discussion on the use of supersymmetry in biological systems, we give examples of the use of supersymmetry for living organism, discuss the codon and anti‐codon ghost fields and develop an algebraic construction for the trash DNA, the DNA area which does not seem active in biological systems. As a general result, all hidden states of codon can be computed by Chern‐Simons 3 forms. Finally, we plot a time series of genetic variations of viral glycoprotein gene and host T‐cell receptor gene by using a gene tensor correlation network related to the Chern‐Simons current. An empirical analysis of genetic shift, in host cell receptor genes with separated cluster of gene and genetic drift in viral gene, is obtained by using a tensor correlation plot over time series data derived as the empirical mode decomposition of Chern‐Simons current.
Information‐Seeking Processes as Temporal Developments: Comparison of Stage‐based and Cyclic Approaches
Authors: Savolainen Reijo
Published: January 2018

Drawing on the ideas of process philosophy, this study elaborates the nature of information‐seeking process by approaching them as temporal developments. To this end, a conceptual analysis was made by comparing key models which approach information seeking as stage‐based and cyclic processes. The nature of such processes was scrutinized by devoting attention to two main aspects, that is, the temporal order in which the constituents of information seeking appear during the process, and the changes occurring in the constituents. Stage‐based approaches draw on linear time concept by conceptualizing such processes as sets of consecutive activities progressing toward a final point. Cyclic approaches conceptualize information‐seeking processes as sets of iterative activities which may be repeated. The findings suggest that stage‐based and cyclic approaches should not be opposite approaches; rather, they complement each other. However, cyclic models emphasizing the importance of feedback loops have gained more popularity in the modeling of web searching, whereas the interest in the development of stage‐based approaches has decreased since the 1990s.
Efficient production and characterization of homopolymeric poly(3‐hydroxyvalerate) produced by Bacillus strain PJC48
Authors: Gu Jin‐Jin , Zhou Ying , Tong Yan‐Bin , Lu Jian‐Jiang , Ye Bang‐Ce
Published: January 2018

Aliphatic polyester, poly(3‐hydroxyvalerate) (PHV), is commonly produced as a granular component in bacterial cells of various species. Based on 16S rDNA gene sequence analysis, strain PJC48 was identified as a Bacillus species. The current study is aimed to screen for a high‐yield strain that can produce PHV efficiently and to increase PHV product yield by optimizing the fermentative process. We identified a high‐producer strain based on Nile red staining. Characterization of the PHV produced by PJC48 by nuclear magnetic resonance spectroscopy revealed that it consisted of (R)‐3‐hydroxyvalerate monomers. The suggested model was validated by response surface methodology. Optimization of the PHV yield resulted in an increase of 32.75% compared to control, with a maximum production of 1.64 g/L after 48 H.
Stillborn Infants: Associated Malformations
Authors: Holmes Lewis B. , Nasri Hanah , Beroukhim Rebecca , Hunt Anne‐Therese , Roberts Drucilla J. , Toufaily M. Hassan , Westgate Marie‐Noel
Published: January 2018

Background

Stillbirth, defined as death of a fetus in utero after 20 weeks of gestation, occurs in 1 to 2% of pregnancies in the United States. Many of these stillborn infants have associated malformations, including chromosome abnormalities, neural tube defects, and malformation syndromes. Other causes are abnormalities of the placenta and maternal conditions, such as pre‐eclampsia and obesity. A consecutive sample of malformed stillborn infants can establish the relative frequency and severity of the associated malformations.

Methods

Stillbirths were identified in the Active Malformations Surveillance Program at Brigham and Women's Hospital (1972–2012). The findings at autopsy, including the findings in the placenta and the results of diagnostic studies, were compiled.

Results

One hundred twenty‐seven stillborn infants with malformations were identified at autopsy among 289,365 pregnancies, including trisomies 21, 18, and 13; 45,X; triploidy; anencephaly; lower urinary tract obstruction; holoprosencephaly and severe heart defects, such as hypoplastic left heart syndrome and tetralogy of Fallot with pulmonary atresia. The severity of the abnormalities in stillborn infants was more severe than the spectrum of abnormalities identified in live‐born infants.

Conclusion

An autopsy of the stillborn fetus, including chromosome microarray and an examination of the placenta, can identify the underlying causes of the stillbirth. This review of stillborn fetuses with malformations showed that several different lethal malformations and heart defects are more common than among live‐born infants. These postmortem examinations can improve the counseling of the parents about risks in future pregnancies. Birth Defects Research 110:114–121, 2018.© 2018 Wiley Periodicals, Inc.
Malformations among infants of mothers with insulin‐dependent diabetes: Is there a recognizable pattern of abnormalities?
Authors: Nasri Hanah Z. , Houde Ng Kara , Westgate Marie‐Noel , Hunt Anne‐Therese , Holmes Lewis B.
Published: January 2018

Background

Infants of diabetic mothers have been shown in several studies to have an increased frequency of malformations. In previous studies, an increased frequency of several specific malformations has been noted, including anencephaly, bilateral renal agenesis, and double outlet right ventricle. Surveillance, used to identify all malformed infants in a consecutive sample of births, can identify a distinctive pattern of malformations among the affected infants.

Methods

The infants of insulin‐dependent, pregestational diabetic mothers were identified in the daily review of the medical records of each newborn infant with a malformation and her/his mother's medical record. Infants of mothers with gestational diabetes were excluded. The frequency of each malformation was compared to that among the malformed infants of nondiabetic mothers.

Results

One hundred and eighty‐three malformed infants of diabetic mothers were identified among the 289,365 births. The most notable malformations were: neural tube defects (anencephaly, 9%), heart defects (transposition of great arteries, 4%), bilateral renal agenesis or dysgenesis (6%), and vertebral anomalies (hemivertebrae, 4%).

Conclusions

There was a recognizable pattern of malformations and characteristics of infants of diabetic mothers, although there was variation in the pattern among affected infants. Some of the malformations in the diabetic embryopathy can be identified in prenatal screening by ultrasound. More important, their occurrence can be reduced significantly by the mother achieving much better control of her diabetes mellitus prior to conception.
Luminescent nanoparticles for rapid monitoring of endogenous acetylcholine release in mice atria
Authors: Mukhametshina Alsu , Petrov Alexey , Fedorenko Svetlana , Petrov Konstantin , Nizameev Irek , Mustafina Asiya , Sinyashin Oleg
Published: January 2018

The present work introduces for the first time a nanoparticulate approach for ex vivo monitoring of acetylcholinesterase‐catalyzed hydrolysis of endogenous acetylcholine released from nerve varicosities in mice atria. Amino‐modified 20‐nm size silica nanoparticles (SNs) doped by luminescent Tb(III) complexes were applied as the nanosensors. Their sensing capacity results from the decreased intensity of Tb(III)‐centred luminescence due to the quenching effect of acetic acid derived from acetylcholinesterase‐catalyzed hydrolysis of acetylcholine. Sensitivity of the SNs in monitoring acetylcholine hydrolysis was confirmed by in vitro experiments. Isolated atria were exposed to the nanosensors for 10 min to stain cell membranes. Acetylcholine hydrolysis was monitored optically in the atria samples by measuring quenching of Tb(III)‐centred luminescence by acetic acid derived from endogenous acetylcholine due to its acetylcholinesterase‐catalyzed hydrolysis. The reliability of the sensing was demonstrated by the quenching effect of exogenous acetylcholine added to the bath solution. Additionally, no luminescence quenching occurred when the atria were pre‐treated with the acetylcholinesterase inhibitor paraoxon.
Nitrogen‐Doped Carbon Xerogels Supporting Palladium Nanoparticles for Selective Hydrogenation Reactions: The Role of Pyridine Nitrogen Species
Authors: Tang Duihai , Sun Xue , Zhao Dan , Zhu Junjiang , Zhang Wenting , Xu Xuelian , Zhao Zhen
Published: January 2018

Nitrogen‐doped carbon xerogels (NDCX) functionalized with various nitrogen functionalities are synthesized and used as supports for Pd nanoparticles (NPs) for selective hydrogenation reactions. The nitrogen doping not only induces the formation of surface basic sites that can connect with the Pd NPs by donating electrons to the unoccupied d orbital of Pd atoms and improve the Pd dispersion, but it also leads to C–N–C hybrid rings that can interact with substrates containing electron‐rich carbon rings, increasing the reaction activity. So far, the Pd/NDCX shows >95 % 1,5‐cyclooctadiene (COD) conversion and cyclooctene (COE) selectivity within 90 min for selective hydrogenation of COD to COE, and the activity can be recovered after washing the catalyst. Moreover, the catalyst can be applied to various substrates containing C=C and/or −NO2 groups with considerable conversion and selectivity. Experimental results and DFT theoretical calculations suggest that the pyridinic nitrogen plays an important role in the reaction, as it is not only the adsorption site of Pd NPs for H2 activation, but it also serves as the active site for COD activation. On these bases, a mechanism for the reaction is proposed.
Anchoring Iron‐EDTA Complex on Graphene toward the Synthesis of Highly Efficient Fe‐N‐C Oxygen Reduction Electrocatalyst for Fuel Cells
Authors: Chang Zhi‐Wen , Meng Fan‐Lu , Zhong Hai‐Xia , Zhang Xin‐Bo
Published: January 2018

Developing nonprecious carbon electrocatalysts as alternatives to platinum for cathodic oxygen reduction reaction in fuel cells is of significance. Herein, an efficient precursor‐controlled synthesis strategy based on extremely rapid nucleation and deposition process assisted by the liquid nitrogen freeze drying method is explored to anchor cheap iron‐EDTA complex evenly dispersed on graphene to realize microstructural homogeneity of the derived Fe‐N‐C oxygen reduction electrocatalyst. The prepared electrocatalyst possesses excellent performance including high activity with more positive onset and half‐wave potential, such long‐term stability, and anti‐poisoning effect compared to commercial Pt/C. The activity correlates well with the unique sheet‐shaped morphology, high surface area, hierarchical porous structure, and the introduction of Fe‐Nx/C species. Especially, both the assembled practical alkaline and acid fuel cells based on the synthesized cathode catalysts reveal excellent performance with high open‐circuit voltage and power density.
Subvalvular aortic stenosis: a review of current literature
Authors: Devabhaktuni Subodh R. , Chakfeh Eyas , Malik Ali O. , Pengson Joshua A. , Rana Jibran , Ahsan Chowdhury H.
Published: January 2018

Subvalvular aortic stenosis (SAS) is one of the common adult congenital heart diseases, with a prevalence of 6.5%. It is usually diagnosed in the first decade of life. Echocardiography is the test of choice to diagnose SAS. Surgical correction is the best treatment modality, and the prognosis is usually excellent. In this review, we describe the pathophysiology, diagnosis, prognosis, and management of SAS with a focus on different pathophysiologic mechanisms, diagnostic approach, and prognosis of the disease by reviewing the current literature.