bluuebunny/crossref_metadata_2025 huggingface dataset:
Fatigue Lifetime Improvement of Aluminum Alloys
Authors: Juijerm Patiphan , Scholtes Berthold
Published: February 2019

Today, aluminum alloys are being considered as substitutes for many automotive parts made from steels because of the growing interest in producing lightweight vehicles. Consequently, it is crucial to understand the fatigue lifetime—the property itself and its behavior—of aluminum alloys, and to clarify its capacities at both room temperature and 1001 elevated temperatures. In particular, the aluminum alloys in the AA5xxx (non-precipitation-hardenable) and AA6xxx (precipitation-hardenable) series are very similar to those found in automotive industries, and are both frequently mentioned and the focus of studies. The satisfactory fatigue lifetime and the improved strength of aluminum alloys make them a strong candidate for automotive industries. This article focuses upon the fatigue property and behavior of aluminum alloys at room temperature and elevated temperatures. Then, the focus will shift to the concept of mechanical surface treatment, the so-called deep-rolling process, which can be used to improve the fatigue lifetime of aluminum alloys. The effects of a mechanical surface treatment on the fatigue properties and behavior of the aluminum alloys AA5083 and AA6110, and the residual stress stability at room temperature and elevated temperatures has been discussed. Moreover, modified deep-rolling processes, i.e., deep-rolling followed by an appropriate annealing process and high-temperature deep-rolling, have been elaborated upon in this article.
Stellite Superalloy Powder Deposition on 7075 Aluminum Alloy
Authors: Casteletti L. C. , Neto A. Lombardi , de Macedo D. T. , Cruvinel L. B. , Totten George
Published: February 2019

Several types of powders can be deposited on metal alloys for property improvement using thermal spray processes. Aircraft grade 7075 aluminum alloy possesses good mechanical properties but poor wear and corrosion resistance. Thermal spray coatings can improve the poor wear performance of 7075 so that it is suitable for use in severe conditions by depositing a hard, wear-resisting layer over the base material. This can be done by a simple production process while maintaining the base material properties. Among the available coatings, cobalt-base superalloys, such as Stellites, provides excellent protection against corrosion and wear. However, the treatment must not deteriorate the substrate hardness. In the High Velocity Oxygen Fuel (HVOF) thermal spray process, the short resident time of the powder in the flame results in a relatively small temperature increase, which in turn results in a lower substrate temperature during the coating deposition. In the present work, HVOF thermal spray process was used to coat 7075-T3 aluminum alloy samples with Stellite 6 superalloy. This treatment resulted in layers of high hardness and improved wear performance while keeping the base material properties unchanged.
Anodic Oxides: Applications and Trends in Nanofabrication
Authors: Stępniowski W.J.
Published: February 2019

Anodic aluminum oxide (AAO) is one of the most frequently fabricated materials with the use of electrochemical techniques. In this article, current trends in aluminum anodizing are reviewed, including anodizing in novel electrolytes, anodizing in electrolytes with various additives, and fabrication of 3D nanostructures using pulse anodizing, leading to the formation of distributed Bragg reflectors. Applications of AAO in the field of nanofabrication are also reviewed with the use of milestone and the most current research.
Quenching of Aluminum Solid Cylinder: Numerical Study
Authors: Jahanian Shahriar
Published: February 2019

A numerical method is presented for evaluating the residual stress distribution in a long aluminum solid cylinder subjected to rapid cooling. An analytical model is developed for the temperature distribution. For the boundary conditions, experimental data for the outer surface of the cylinder are used, and a reasonable agreement between the predicted temperature distribution at the center of the cylinder and the experimental data is observed. For the numerical analysis, a quasi-static, uncoupled thermoelastoplastic analysis, based on a hyperbolic sine law, is presented. The numerical results are presented for the temperature distribution as well as the thermoelastoplastic stress distribution in a solid cylinder with temperature-dependent properties. The residual stress distribution is compared with the results of other investigators who used the Finite Element Method, and a reasonable agreement between our results and previous results is observed. The conclusion is reached that the temperature dependency of the yield stresses and the problem of post-yielding are two important factors to be considered when developing a model for predicting the residual stresses in quenched bodies.
Chemical Milling of Aluminum
Authors: Griffin Bruce M.
Published: February 2019

Chemical milling involves the development of etchants and masking agents for the manufacture of filter elements for internal combustion engines, cut recesses in bearing journals, creation of printed circuits, manufacture of large structures used in the aerospace industry and many more applications. This article will address: chemical milling process steps, overview of maskants, tooling, area rules, overview of etchants, quality issues, and material selection for tanks and part racking.
Steel: Aluminum Coatings
Authors: Bahadur Aruna
Published: February 2019

Aluminum coated steel possesses excellent oxidation and corrosion resistance in sulfur and marine: environments and can substitute for expensive alloy of steels. Hot dip aluminizing (HDA) and pack cementation calorizing (CAL) are dealt with in detail. IN HDA coats, some alloying action takes place, when the substrate is dipped in molten Al at 973 K for 1–2 minutes. The coat consists of an outer pure Al layer, followed by a hard intermetallic layer consisting of FeAl3 and Fe2Al5, forming a serrated interface with the base. Isothermal holding of such samples at 773–933 K for 10 minutes leads to further diffusion and phase changes. This improves resistance to thermal shock and bending. In CAL coats, the process parameters (1173–1223 K/2–4 h and pack composition), were optimized, resulting in appreciable alloying. The surface layer consists of Fe3Al and FeAl, which is comparable to the inner alloy layer of HDA coats. The structure/ property correlation is carried out for both coatings and the results compared.
Intermetallics of Aluminum
Authors: Frommeyer Georg , Knippscheer Sven
Published: February 2019

Aluminum-rich intermetallic compounds of the Al3X-type with transmission metals (X = Ti. Zr, Nb, V) of Groups IVb and Vb are of interest in the development of novel high-temperature and lightweight structural materials. This article describes the important physical and mechanical properties of trialuminides with DO22 structure and their L12 variations. Topical coverage includes: crystal structure and selected physical properties, plastic deformation, oxidation behavior, and applications.
Brazing of Aluminum Alloys
Authors: Sugiyama Y.
Published: February 2019

This article gives an outline of the features that different brazing methods and materials share in common, and discusses the mechanism, materials, special features and conditioning factors of vacuum brazing in particular.
Casting Designs
Authors: Stoll Henry W.
Published: February 2019

This article addresses issues and practices associated with aluminum casting design. The focus is on aluminum casting design generally including expendable molds and permanent molds. Topics addressed include: casting processes, design related casting defects, mechanical property variation, geometry and material process interactions, thermal post processing, tooling, design related cost drivers, casting design guidelines and concurrent engineering.
Creation of Master Alloys for Aluminum
Authors: Gasik Michael M. , Mazur Vladislav I.
Published: February 2019

This article addresses the use of master alloys used primarily for grain refinement of aluminum and its alloys. However the use of master alloys for microstructure and property control is also discussed. Specific topics include: principles and classification of master alloys, physical metallurgy of basic master alloy systems, applications of master alloys, and techniques for microstructure modification and property improvement.
Design of Forming Processes: Sheet Metal Forming
Authors: Wanheim T.
Published: February 2019

This article addresses sheet metal deformations processes and are classified as secondary processing methodologies. Sheet metal forming processes are further classified as processes with: compressive stresses, tensile stresses, compressive and tensile stresses, bending, and shear. Additional discussion on sheet metal processing includes: process metallurgy and microstructure, process design, processing parameters, prevention of failures, formability and testing, and modeling.
Designing for Aluminum
Authors: Kuhn Howard A.
Published: February 2019

In the design of aluminum forgings, the designer must specify the material and process and geometric details so that the component will meet performance requirements. Forging produces parts of high integrity because the process sequences refines and homogenizes metallurgical structure, elimination of material defects assuring maximum material strength. This article specifically addresses the following forging design considerations: material aspects, geometrical aspects, cost aspects, forging methods, process mechanics, and forged part design.
Bulk Metallic Glasses: Aluminum-Based
Authors: Yang B.J. , Yao J.H. , Wang J.Q. , Chao Y.S. , Ma E.
Published: February 2019

This paper details a systematic investigation of the formation of Al-based bulk metallic glasses, expanding on an earlier brief report.[] We discuss an approach for designing and predicting the best glass-forming composition in the Al–TM–RE systems, based on the atomic cluster packing model for the internal structure of the glass. The effects of additional elements in quaternary and quinary systems on the glass-forming ability and thermal stability of the glasses are also discussed. Three new compositions, Al86Ni6Y4.5Co2La1.5, Al86Ni7Y5Co1La1 and Al86Ni7Y4.5Co1La1.5, are capable of forming fully glassy rods of 1 mm in diameter; their glass transition and other thermal properties are systematically characterized.
Diffusion Bonding of A2017 Aluminum Alloys
Authors: Latouche T. , Cailler M. , Sander B. , Marya S.K.
Published: February 2019

Diffusion bonding is a solid phase welding process in which bonding occurs through coalescence of the surfaces in contact. The principal operating parameters of diffusion bonding are the temperature, pressure and the bonding time. In addition to diffusion, other mechanisms such as microscopic creep or recrystallization also contribute to the formation and development of the bond. This article examines the influence of the surface oxide and welding atmosphere on mechanical characteristics of the bonded joint.
Electrochemical Study of Potassium Fluoride in a Cryolite-Aluminum Oxide Molten Salt
Authors: Tao Shaohu , Peng Jianping , Di Yuezhong , Liu Kejia , Zhao Kun , Feng Naixiang
Published: February 2019

Selective and efficient electrochemical methods to characterize aluminum are necessary. Current methods are based on potentiodynamic polarization, recurrent potential double pulses, chronopotentiometry, open-circuit chronopotentiometry, and potentiostatic electrolysis, but have not been used to characterize the deposition of aluminum in Na3AlF6-Al2O3-KF molten salts. The control processes of the formation of aluminum-tungsten inter-metallic compounds, and the deposition of aluminum have been investigated by using steady-state potentiodynamic cathodic polarization curves. The dissolution loss rate of aluminum was determined with an increase in KF concentration by the analysis of recurrent potential double pulses. Using chronopotentiometry, it was confirmed that the deposition potential of aluminum shifted more negative as the KF concentration increased, and a higher KF concentrations induced a higher cathodic overpotential. From open-circuit potential measurements and scanning electron micrographs, it was concluded that aluminum(III) ions react with tungsten substrates to form an aluminum-tungsten compound, and the reaction mechanism of aluminum was determined. These electrochemical methods applied with aluminum electrolysis were accurate, efficient, and reliable.
Electron-Beam Welding of Thick Components of Steels, Aluminum, and Titanium Alloys
Authors: Martynov V.N. , Khokhlovskii A.S. , Sliva A.P.
Published: February 2019

In this paper, conditions for vertical weld defectless formation at horizontal electron-beam welding (EBW) are shown and power-complex selection methods to weld thick-walled constructions by electron beam are developed. Dependences to estimate EBW optimal conditions are obtained.
Entrainment Defects
Authors: Campbell J.
Published: February 2019

Most metals start their lives in the liquid state, and are subjected to various transfers involving pouring or other types of surface turbulence. These actions entrain (fold in) the surface film to create entrainment defects. These are principally (a) bubbles that in turn create bubble trails; (b) bifilms; doubled over surface films, that act as cracklike defects; and (c) sundry entrained debris, collectively known as exogenous inclusions. The bifilm is the subject of this perspective. It appears to be a common, but serious and almost overlooked metallurgical defect. Analysis of bifilms provides a simple, powerful and elegant concept based on an enduring legacy from turbulence during the pouring of liquid metals. Usually large populations of bifilms are introduced into metals at an early stage of their production. In general their presence has been unsuspected because although they can have large area, they can often be only nanometres thick and not easily detected by conventional non-destructive techniques. The populations of cracks in suspension in liquid metal explains many otherwise inexplicable features of cast products such as porosity, hot tearing, the morphologies of second phases, and impaired reliability of mechanical properties. The fundamental difference between such entrained defects (associated with a macroscopic unbonded interface) and defects and inclusions grown in the melt is seen to be of central significance for the failures of metals by mechanical or corrosion type mechanisms. For wrought products the continued presence of bifilms, now usually extended and elongated and mainly occupying grain boundaries, appears to offer explanations for many metallurgical phenomena. Bifilms are likely to influence the development of texture, and are the most likely source for many types of failure in the solid state. Thus the limitations to superplastic forming, cavitation in tertiary creep, pitting corrosion of various types and stress corrosion cracking are likely to be profoundly affected by bifilms. Although the effects of bifilms can be reduced by expensive post-casting operations such as hipping or working, the major future potential lies in techniques for their avoidance. Some casting operations are already taking some first steps in new technology for their avoidance, and benefiting technically and commercially.
Friction Welding of Al2O3P/6061 Aluminum Alloy Composite to 5052 Aluminum Alloy
Authors: Kato K. , Tokisue H.
Published: February 2019

6061 aluminium alloy matrix composite containing 20.5 vol% particulate alumina and 5052 aluminium alloy were welded using a brake type friction welding machine. The microstructures and mechanical properties of the friction welded joints were investigated. The mechanically mixed regions and the alumina particles which had moved to the other part of the composite alloy were observed clearly on the weld interface. The hardness at the weld interface showed higher values than those of the base metals. The variation of hardness on the composite material side was not very significant, but a softened area could be seen in the heat affected zone of the 5052 aluminium alloy side and recovery to the same level of hardness as that of the 5052 aluminium alloy base metal could be found at about 20 mm from the weld interface. Regardless of the welding conditions, the joint efficiency in terms of tensile strength was 95–101% of that of the composite material base metal and the maximum elongation was 71% of that of the composite material base metal. Friction welded joints with good joint efficiency fractured near the weld interface of the heat affected zone of the composite base metal. The impact values of the welded joints with a notch in the weld interface were about 70% of those of the composite material base metal.
Hardening, Annealing, and Aging
Authors: Ketgerman Laurens , Eskin D.
Published: February 2019

Aluminum alloys can be divided into two groups: casting alloys and wrought alloys. This article focuses on aluminum wrought alloys. This article will address the hardening, annealing and aging processes of wrought aluminum alloys. Specific topics to be addressed include: hardening mechanisms, annealing, heat treatment, quenching, aging of various commercial aluminum alloys, aluminum-lithium (Al-Li) alloys, precipitation phenomena.
Image Processing for Fault Detection in Aluminum Castings
Authors: Mery Domingo , Filbert Dieter , Jaeger Thomas
Published: February 2019

In this article, a review of the use of image processing as a tool in the automated visual inspection of aluminum castings is provided. Methodologies and principles are outlined. This discussion includes detained overviews of: digital image processing in x-ray testing and defect detection in castings.
Microgravity Crystallization for High-Tech Castings
Authors: Tensi Hans M.
Published: February 2019

In this article, an overview of the development of microgravity crystallization of aluminum castings will be provided. Topics to be discussed include: industrial process development, microgravity experiments performed in space, and development of high-strength castings in microgravity environments.
Machining
Authors: Jawahir I.S. , Balaji A.K.
Published: February 2019

Machining is one of the most important manufacturing processes. Aluminum and its alloys play a critical role in component manufacture. This article will provide the reader with a current overview of machining practices which will include: aluminum alloy classification, machining performance measures such as cutting forces, tool life, chip forming and breakability, cutting tool design, and area that provide continuing process challenges such as high-speed machining, dry machining and machining of aluminum metal matrix composites.
Metallurgy of Continuous Hot Dip Aluminizing
Authors: Richards R.W. , Clarke H. , Jones R.D. , Clements P.D.
Published: February 2019

In spite of a strong commercial interest in hot dipped aluminised steel strip, research over the past 60 years has been somewhat piecemeal. A relatively smaller body of work exists on this material compared with the equivalent galvanised product but the lack of systematic study and development means that it is difficult to rationalise and appraise the existing literature. This review is intended to provide an overall view of the salient results of previous work, providing key entry points to available literature.

IMR/269© 1994 The Institute of Materials and ASM International. At the time the work was carried out Dr Richards and Mr Clarke were in the Division of Materials and Minerals Engineering, School of Engineering, University of Wales, Cardiff, UK. Dr Jones is in the Faculty of Technology, North East Wales Institute, Wrexham, Clwyd, UK and Dr Clements is with British Steel pic, Llanwern Works, Newport, Gwent, UK.
Molten Metal Processing
Authors: Otsuka Ryotatsu
Published: February 2019

Molten metal processing in the aluminum industry and process development has made a great impact on cost performance and quality assurance of aluminum products. This article focuses on molten aluminum refining methods. The topical coverage addresses removal of hydrogen, inclusions and alkali metals from molten aluminum.
Welding: Particulate and Gaseous Emissions
Authors: Homer Cole , Seymour Epstein , Jon Peace
Published: February 2019

Fabrication and repair of aluminum components and structures commonly involves the use of electric arc welding. The interaction of the arc and the metal being welded generates ultraviolet radiation, metallic oxides, fumes, and gases. Aluminum is seldom used as the pure metal but is often alloyed with other metals to improve strength and other physical properties. Therefore, the exact composition of any emissions will depend on the welding process and the particular aluminum alloy being welded. To quantify such emissions, The Aluminum Association sponsored several studies to characterize arc welding emissions by the gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW) processes for various combinations of base and filler alloys. In all cases, the tests were conducted under conditions that could be found in a production weld shop without forced ventilation. The concentrations of each analyte that a welder could be exposed to were greatly affected by the welding process, the composition of the base and filler alloys, the position of the welder, and the welding helmet. The results obtained can be used by employers to identify and control potential hazards associated with the welding of aluminum alloys and can provide the basis for hazard communication to employees involved in the welding of these alloys.
Recycling of Aluminum
Authors: Soares Tenório Jorge Alberto , Espinosa Denise Crocce Romano
Published: February 2019

Aluminum is the second most used metal in the world because of its properties including good corrosion resistance, low density, high electrical conductivity and good thermal conductivity. However, the negative environmental impact from production of primary aluminum is due to the corresponding impact of red mud and release of fluorides which is devastating to forests and the space required for waste disposal. Recycling, in addition to reducing the impact of disposal of the by-products of primary aluminum production also consumes a great amount of electricity. Therefore, recycling of aluminum scrap is of increasing interest. In this article, the following factors involved in aluminum recycling are discussed: environmental and energy impact, secondary metallurgy of aluminum, fundamentals of aluminum recovery using salt flux, recovery of aluminum drosses by milling and preliminary treatments of scrap.
Iron: Removal from Aluminum
Authors: Zhang Lifeng , Gao Jianwei , Wiredu Damoah Lucas Nana , Robertson David G.
Published: February 2019

In this paper, the Fe-rich phases in and their detrimental effect on aluminum alloys are summarized. The existence of brittle platelet β-Fe-rich phases lowers the mechanical properties of aluminum alloys. The methods to neutralize the detrimental effect of iron are discussed. The use of high cooling rate, solution heat treatment, and addition of elements such as Mn, Cr, Be, Co, Mo, Ni, V, W, Cu, Sr, or the rare earth elements Y, Nd, La, and Ce are reported to modify the platelet Fe-rich phases in aluminum alloys. The mechanism of the modification is briefly described. Technologies to remove iron from aluminum are reviewed extensively. The precipitation and removal of Fe-rich phases (sludge) are discussed. The dense phases can be removed by methods such as gravitational separation, electromagnetic (EM) separation, and centrifuge. Other methods include electrolysis, electro-slag refining, fractional solidification, and fluxing refining. The expensive three-layer cell electrolysis process is the most successful technique to remove iron from aluminum so far.
Porosity Development and Modification in Al-Si Alloys: Effect of P and Sr
Authors: Campbell J. , Tiryakioğlu Murat
Published: February 2019

The benefits of Sr additions to Al–Si alloys to modify the eutectic are often impaired by the development of porosity, sometimes to the degree that benefits are negated. Experimental reports are reviewed in this paper, suggesting an explanation in terms of the oxide population in the melt. The unmodified silicon particles are nucleated by AlP, which has in turn nucleated on oxide bifilms. The oxide bifilms, which are essentially cracks, are straightened by the crystalline growth of Si particles, leading to increased crack size and consequently reduced mechanical properties. The addition of Sr improves properties by suppressing the formation of Si on bifilms and thereby preventing the straightening of the pre-existing cracks. Si is now forced to precipitate at a lower temperature as a coral-like eutectic. Unfortunately, the bifilms are now freed (the primary Si particles no longer exist to grow around and sequester the bifilms), remaining in suspension in the liquid metal, allowing them to act to block interdendritic flow and aid the initiation of the formation of pores, countering the benefits of the improved structure.
Rolling of Aluminum
Authors: Karhausen Kai F. , Korhonen Antti S.
Published: February 2019

Because of its lightweight and strength, aluminum alloys are used are being used increasing for the production of lightweight construction. In addition to applications in the expanding transportation market, aluminum sheet and foil materials are traditionally used for food and medical packaging, thin foil, and fin stock for air conditioners and heat exchangers, decorative panels and lithographic sheet. Rolling is a process used for the production of strip or sheet. In this article, rolling processing of aluminum and aluminum alloys is discussed in detail and specific processes include: hot-rolling, cold-rolling, and rolling of aluminum foils.
Superplastic Forming
Authors: Ridley Norman
Published: February 2019

An inherent limitation of conventional aluminum alloys is that they are unstable when plastically deformed by stretching which leads to catastrophic necking when tensile testing and limitations on uniform deformation during stretch forming under tensile stress. This has led to the development of superplastic forming (SPF) process development used for the production of products for structural and non-structural applications in industries such as aerospace, automotive, architecture, transport and others. This article provides a general overview of superplastic forming and addresses: identification and characterization of superplastic alloys, processing of superplastic alloys, cavitation and failure, superplastic forming, simulation, and applications and mechanical properties.
Surface Chemistry of Adhesion to Aluminum
Authors: Hyland Margaret M.
Published: February 2019

Understanding the microstructure and chemistry of the aluminum surface is the key to designing coating and structural bonding systems that endure. The focus of this article is the examination of concepts common to all polymer/aluminum bonding applications and to discuss some common surface treatments alter the surface chemistry and microstructure and how these treatments affect adhesion. Topics covered in this review include: discussion of the untreated aluminum surface, adhesion to aluminum surfaces, prevention of hydration of the bonded interface, and pretreatments,
Arc-Welding: Lithium-Containing Aluminum Alloys
Authors: Ryazantsev V.I. , Fedoseev V.A.
Published: February 2019

The development of structures in the aerospace industry is associated mainly with the application of advanced methods and new technologies. Promising metals include alloys containing lithium (the lightest metal, its density is 543 kg/m3). The use of these alloys in welded structures reduces the weight by 20–25% in comparison with structures produced using conventional aluminium alloys such as D16, V95, etc. This article shows that alloys of aluminium with lithium of all alloying systems have metallurgical and technological special features which must be taken into account when producing welded sections by fusion welding.
Thermal Analysis of Aluminum Alloys
Authors: García-Cordovilla Consuelo , Louis Enrique
Published: February 2019

Microstructural characterization of aluminum alloys is typically performed by combining microscopy techniques with measurement of physical properties such as conductivity and hardness. Relatively recently calorimetric techniques have been used to complement the more traditional methodologies. This article will discuss: basic principles, instrumentation and experimental procedures, reaction kinetics, and general rules for interpreting DTA and DSC data. Heat treatable, non-heat treatable alloy and aluminum-based composite characterization are discussed.
Metallurgy of Quenching Aluminum Alloys
Authors: Shuey Ralph T. , Tiryakioğlu Murat
Published: February 2019

The present authors have collaborated since 2000 on revitalizing and extending the technology for metallurgical aspects of quenching heat-treatable aluminum alloys, which had been developed by Dr. James T. Staley, Sr. starting with Ref. [] and continued until his retirement from Alcoa three decades later. Our objective in this chapter is a concise and current overview of what came before us and what we have added. For this we have surveyed the open literature as well as Alcoa files going back into the 1940’s, excluding any details that might still be considered proprietary. We suppose our reader to be soundly grounded in metallurgical engineering, but not necessarily with any knowledge specific to aluminum. We have excluded the topic of quench-aging, the combination of quenching and aging into a continuous process, as a substantive survey would be heavy in proprietary concepts and sophisticated metallurgy. We have also excluded thermal and mechanical aspects of quenching aluminum alloys, as well as equipment and quenchants used in fabrication of aluminum products. On these topics much of the information presented elsewhere in this volume, is generally applicable to aluminum. We conclude with our views on what has been established, how to use it, and where to go next with the techniques pioneered by our mutual mentor, Dr. James T. Staley.
Drug Calculation Errors in Anesthesiology Residents and Faculty: An Analysis of Contributing Factors
Authors: Black Shira , Lerman Jerrold , Banks Shawn E. , Noghrehkar Dena , Curia Luciana , Mai Christine L. , Schwengel Deborah , Nelson Corey K. , Foster James M. T. , Breneman Stephen , Arheart Kris L.
Published: February 2019

BACKGROUND:

Limited data exist regarding computational drug error rates in anesthesia residents and faculty. We investigated the frequency and magnitude of computational errors in a sample of anesthesia residents and faculty.

METHODS:

With institutional review board approval from 7 academic institutions in the United States, a 15-question computational test was distributed during rounds. Error rates and the magnitude of the errors were analyzed according to resident versus faculty, years of practice (or residency training), duration of sleep, type of question, and institution.

RESULTS:

A total of 371 completed the test: 209 residents and 162 faculty. Both groups committed 2 errors (median value) per test, for a mean error rate of 17.0%. Twenty percent of residents and 25% of faculty scored 100% correct answers. The error rate for postgraduate year 2 residents was less than for postgraduate year 1 (P = .012). The error rate for faculty increased with years of experience, with a weak correlation (R = 0.22; P = .007). The error rates were independent of the number of hours of sleep. The error rate for percentage-type questions was greater than for rate, dose, and ratio questions (P = .001). The error rates varied with the number of operations needed to calculate the answer (P < .001). The frequency of large errors (100-fold greater or less than the correct answer) by residents was twice that of faculty. Error rates varied among institutions ranged from 12% to 22% (P = .021).

CONCLUSIONS:

Anesthesiology residents and faculty erred frequently on a computational test, with junior residents and faculty with more experience committing errors more frequently. Residents committed more serious errors twice as frequently as faculty.
A Multivariable Model Predictive of Unplanned Postoperative Intubation in Infant Surgical Patients
Authors: Eisler Lisa D. , Hua May , Li Guohua , Sun Lena S. , Kim Minjae
Published: February 2019

BACKGROUND:

Unplanned postoperative intubation is an important quality indicator, and is associated with significantly increased mortality in children. Infant patients are more likely than older pediatric patients to experience unplanned postoperative intubation, yet the literature provides few characterizations of this outcome in our youngest patients. The objective of this study was to identify risk factors for unplanned postoperative intubation and to develop a scoring system to predict this complication in infants undergoing major surgical procedures.

METHODS:

In this retrospective cohort study, The National Surgical Quality Improvement Program-Pediatric database was surveyed for all infants who underwent noncardiac surgery between January 1, 2012 and December 31, 2015 (derivation cohort, n = 56,962) and between January 1 and December 31, 2016 (validation cohort, n = 20,559). Demographic and perioperative clinical characteristics were examined in association with our primary outcome of unplanned postoperative intubation within 30 days of surgery. Risk factors were analyzed in the derivation cohort (2012–2015 data) using multivariable logistic regression with stepwise selection. Parameters from the final model were used to create a scoring system for predicting unplanned postoperative intubation. Data from the validation cohort were utilized to assess the performance of the scoring system using the area under the receiver operating characteristic curve.

RESULTS:

In the derivation cohort, 2.2% of the infants experienced unplanned postoperative intubation within 30 days of surgery. Of the 14 risk factors identified in multivariable analysis, 10 (age, prematurity, American Society of Anesthesiologists physical status, inpatient status, operative time >120 minutes, cardiac disease, malignancy, hematologic disorder, oxygen supplementation, and nutritional support) were included in the final multivariable logistic regression model to create the risk score. The area under the receiver operating characteristic curve of the final model was 0.86 (95% CI, 0.85–0.87) for the derivation cohort and 0.83 (95% CI, 0.82–0.85) for the validation cohort.

CONCLUSIONS:

About 1 in 50 infants undergoing major surgical procedures experiences unplanned postoperative intubation. Our scoring system based on routinely collected perioperative assessment data can predict risk in infants with good accuracy. Further investigation should assess the clinical utility of the scoring system for risk stratification and improvement in perioperative care quality and patient outcomes.
Effects of the PIWI/MID domain of Argonaute protein on the association of miRNAi's seed base with the target
Authors: Wang Zhen , Wang Yanli , Liu Taigang , Wang Yujie , Zhang Wenbing
Published: February 2019

The small interfering RNAs (siRNA) or microRNAs (miRNA) incorporated into the RNA-induced silencing complex with the Argonaute (Ago) protein associates with target mRNAs through base-pairing, which leads to the cleavage or knockdown of the target mRNA. The seed region of the s(m)iRNA is crucial for target recognition. In this work, a molecular dynamic simulation was utilized to study the thermodynamics and kinetic properties of the third seed base binding to the target in the presence of the PIWI/MID domain of Ago. The results showed that in the presence of the PIWI/MID domain, the entropy and enthalpy changes for the association of the seed base with the target were smaller than those in the absence of protein. The binding affinity was increased due to the reduced entropy penalty, which resulted from the preorganization of the seed base into the A-helix form. In the presence of the protein, the association barrier resulting from the unfavorable entropy loss and the dissociation barrier coming from the destruction of hydrogen bonding and base-stacking interactions were lower than those in the absence of the protein. These results indicate that the seed region is crucial for fast recognition and association with the correct target.
A hundred years of rabies in Kenya and the strategy for eliminating dog-mediated rabies by 2030
Authors: Bitek Austine O , Osoro Eric , Munyua Peninah M , Nanyingi Mark , Muthiani Yvonne , Kiambi Stella , Muturi Mathew , Mwatondo Athman , Muriithi Rees , Cleaveland Sarah , Hampson Katie , Njenga M. Kariuki , Kitala PM , Thumbi SM
Published: February 2019

Background: Rabies causes an estimated 59,000 human deaths annually. In Kenya, rabies was first reported in a dog in 1912, with the first human case reported in 1928. Here we examine retrospective rabies data in Kenya for the period 1912 – 2017 and describe the spatial and temporal patterns of rabies occurrence in the country. Additionally, we detail Kenya’s strategy for the elimination of dog-mediated human rabies by 2030.

Methods: Data on submitted samples and confirmed cases in humans, domestic animals and wildlife were obtained from Kenya’s Directorate of Veterinary Services. These data were associated with the geographical regions where the samples originated, and temporal and spatial trends examined.

Results: Between 1912 and the mid 1970’s, rabies spread across Kenya gradually, with fewer than 50 cases reported per year and less than half of the 47 counties affected. Following an outbreak in the mid 1970’s, rabies spread rapidly to more than 85% of counties, with a 4 fold increase in the percent positivity of samples submitted and number of confirmed rabies cases. Since 1958, 7,584 samples from domestic animals (93%), wildlife (5%), and humans (2%) were tested. Over two-thirds of all rabies cases came from six counties, all in close proximity to veterinary diagnostic laboratories, highlighting a limitation of passive surveillance.

Conclusions: Compulsory annual dog vaccinations between 1950’s and the early 1970’s slowed rabies spread. The rapid spread with peak rabies cases in the 1980’s coincided with implementation of structural adjustment programs privatizing the veterinary sector leading to breakdown of rabies control programs. To eliminate human deaths from rabies by 2030, Kenya is implementing a 15-year step-wise strategy based on three pillars: a) mass dog vaccination, b) provision of post-exposure prophylaxis and public awareness and c) improved surveillance for rabies in dogs and humans with prompt responses to rabies outbreaks.
Does the mouse tail vein injection method provide a good model of lung cancer?
Authors: Shrestha Nensi , Lateef Zabeen , Martey Orleans , Bland Abigail R. , Nimick Mhairi , Rosengren Rhonda , Ashton John C.
Published: February 2019

Lung cancer drug development requires screening in animal models. We aimed to develop orthotopic models of human non-small lung cancer using A549 and H3122 cells delivered by tail vein injection. This procedure has been used previously for a mouse lung cancer (Lewis lung carcinoma) and as a model of human breast cancer metastasis to lung. We report that the procedure led to poor animal condition 7-8 weeks after injection, and produced lesions in the lungs visible at necropsy but we were unable identify individual cancer cells using immunohistochemistry. We conclude that if this method is to produce a model that can be used in drug experiments, improvements are required for cancer cell detection post mortem, such as by using of a fluorescently tagged human lung cancer cell line.
Autism and social anxiety in children with sex chromosome trisomies: an observational study
Authors: Wilson Alexander C. , King Judith , Bishop Dorothy V.M.
Published: February 2019

Background: Recent studies suggest that an extra sex chromosome increases the risk of both autism and social anxiety, but it unclear whether these risks are specific to particular karyotypes.

Methods: We considered diagnostic data from an online psychiatric assessment (DAWBA – The Development and Well-Being Assessment) and questionnaire responses completed by parents of children with 47,XXX (N = 29), 47,XXY (N = 28) and 47,XYY (N = 32) karyotypes. Analysis focused mainly on 54 children who were diagnosed prenatally or on the basis of other medical concerns in childhood (Low Bias subgroup), to minimise ascertainment bias.

Results: Children with symptoms of autism who fell short of meeting the Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV criteria were coded as cases of Pervasive Developmental Disorder Not Otherwise Specified (PDDNOS). The odds ratio of autism or PDDNOS in the Low Bias group was computed relative to gender-specific population norms. This gave log odds ratio (95% confidence interval) of 5.56 (4.25 - 6.88) for XXX girls; 4.00 (2.66 - 5.33) for XXY boys; and 4.60 (3.46 - 5.74) for XYY boys. Despite this elevated risk, most children had no autistic features. A diagnosis of DSM-IV Social Phobia was rare, though, in line with prediction, all three Low Bias cases with this diagnosis had 47,XXY karyotype. All three trisomy groups showed increased risk of milder symptoms of social anxiety.

Conclusions: An increased risk of autism was found in girls with 47,XXX karyotype, as well as in boys with 47,XXY or 47,XYY. Symptoms of social anxiety were increased in all three karyotypes. There was wide variation in psychiatric status of children with the same karyotype, suggesting that an extra sex chromosome affects developmental stability in a non-specific way, with a diverse range of possible phenotypes.
Summer Pedagogical Practice As a Part of Professional Training of Students
Authors: Павлова Н. , Pavlova N. , Борисова М. , Borisova M.
Published: February 2019

The article deals with the organization of summer teaching practice, approaches to the training of counselors. It is said about the pedagogical potential of summer practice as a form of improving the quality of professional training of future teachers, improving the skills of pedagogical activity.
Interdependence, Perception, and Investment Choices: An Experimental Approach to Decision Making in Innovation Ecosystems
Authors: Adner Ron , Feiler Daniel
Published: February 2019

We explore how decision makers perceive and assess the level of risk in interdependent settings. In a series of five experiments, we examine how individuals set expectations for their own project investments when their success is contingent on the success of multiple, independent partners. We find that individuals are subjectively more confident and optimistic in an interdependent venture when its chances of success are presented as separate probabilities for each component and that this optimism is exacerbated by a greater number of critical partners, leading to (1) the inflation of project valuations, (2) the addition of excessive partners to a project, and (3) overinvestment of effort in the development of one’s own component within an interdependent venture. We examine these dynamics in settings of risky choice (with exogenously given probabilities) and in an economic coordination game (with the ambiguity of agency and strategic risk). We conduct our study with a wide range of participant samples ranging from undergraduates to senior executives. Collectively, our findings hold important implications for the ways in which individuals, organizations, and policymakers should approach and assess their innovation choices in ecosystem settings.
The role of collagenase ointment in acute burns: a systematic review and meta-analysis
Authors: Pham Christopher H , Collier Zachary J , Fang Mike , Howell Anna , Gillenwater Timothy J
Published: February 2019

Objective:

A systematic review and meta-analysis was performed to summarise the state of the literature in regard to the efficacy and uses of clostridial collagenase ointment (CCO) in the burn patient.

Method:

A systematic review of articles available on PubMed, Scopus and OvidSP Medline was performed. Keywords used in the search process included burns, thermal injury, collagenase, enzymatic debridement, wound care. Reviews, case reports, independent abstracts, consensus and opinion papers were excluded. A meta-analysis was performed for articles fitting inclusion criteria.

Results:

Following screening, six relevant articles were identified for systematic review. Few studies, with limited sample sizes, argue that CCO may be an effective debriding agent. It may also accelerate wound healing and avoid the pain associated with mechanical debridement. CCO lacks antimicrobial activity but the risk of burn wound infection does not appear to be significantly different than when using silver-impregnated products. CCO is more expensive than traditional wound care products but may help halt burn depth conversion and prevent the need for surgery.

Conclusion:

CCO may be a safe and effective debridement agent for burn wounds with respect to decreasing wound healing time and minimising pain without increasing the risk of infection. It should be used on a case-by-case basis due to its financial cost, which may be offset by its ability to manage burns non-operatively.
The perfect mix
Authors: Hart Karen
Published: February 2019

Used together, sand and water play provide children with many exciting opportunities for creativity. Children engage all their senses as they explore textures, changing colours and shifting patterns.
Adsorption and Desorption Behavior of Herbicide Mefenpyr-diethyl in the Agricultural Soils of Morocco
Authors: El Boukili Abdellah , Loudiyi Nidae , El Bazaoui Ahmed , El Hourch Abderrahim , Taibi M'Hamed , EL Boukili Abderrahman
Published: February 2019

The present study was conducted in order to investigate the adsorption and desorption behavior of Mefenpyr-diethyl (MFD) using the batch equilibration technique in four soils, with different ranges of organic matter content, from different regions of Morocco orders of Benimellal (Soil 1), Settat (Soil 2), Sidi Bettach (Soil 3) and EL Hajeb (Soil 4). The adsorption isotherm models Langmuir, linear and Freundlich were used to compare the adsorption capacity of the soils. The results indicated that the Freundlich equation provided the best fit for all adsorption data. The values of KF and Kd ranged from 4.45 to 15.9 and 4.30 to 18.30 L.kg-1 , respectively. The calculated total percentage of desorption values from the Soil 1, Soil 2, Soil 3 and Soil 4 after the four desorption process were 59 %; 55,6 %; 37,5 % and 52,5%, respectively. Highest adsorption and desorption were observed in soil 1, and the lowest was in soil 3. According to the adsorption and desorption results, organic matter and clay seemed to be the most important factors influencing the adsorption capacity of MFD.
Spatiotemporal Expression of Three Secretoglobin Proteins, SCGB1A1, SCGB3A1, and SCGB3A2, in Mouse Airway Epithelia
Authors: Naizhen Xu , Kido Taketomo , Yokoyama Shigetoshi , Linnoila R. Ilona , Kimura Shioko
Published: February 2019

Secretoglobins (SCGBs) are cytokine-like small molecular weight secreted proteins with largely unknown biological functions. Three SCGB proteins, SCGB1A1, SCGB3A1, and SCGB3A2, are predominantly expressed in lung airways. To gain insight into the possible functional relationships among the SCGBs, their protein and mRNA expression patterns were examined in lungs during gestation and in adult mice, using Scgb3a1-null and Scgb3a2-null mice as negative controls, by immunohistochemistry and by qRT-PCR analysis, respectively. The three SCGBs exhibited unique spatiotemporal expression patterns during embryogenesis. The lack of Scgb3a1 or Scgb3a2 did not affect expression of the other Scgb genes as determined by mRNA measurements. Moreover, the lack of Scgb3a1 or Scgb3a2 did not affect development of the pulmonary neuroepithelial bodies during embryogenesis, while the lack of Scgb3a2 may have resulted in slightly fewer ciliated cells than in the wild-type. These results suggest that SCGB1A1, SCGB3A1, and SCGB3A2 each may possess its own unique biological function.